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  Subjects -> ELECTRONICS (Total: 179 journals)
Showing 1 - 200 of 277 Journals sorted alphabetically
Acta Electronica Malaysia     Open Access  
Advances in Biosensors and Bioelectronics     Open Access   (Followers: 7)
Advances in Electrical and Electronic Engineering     Open Access   (Followers: 5)
Advances in Electronics     Open Access   (Followers: 78)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Microelectronic Engineering     Open Access   (Followers: 13)
Advances in Power Electronics     Open Access   (Followers: 33)
Advancing Microelectronics     Hybrid Journal  
Aerospace and Electronic Systems, IEEE Transactions on     Hybrid Journal   (Followers: 313)
American Journal of Electrical and Electronic Engineering     Open Access   (Followers: 24)
Annals of Telecommunications     Hybrid Journal   (Followers: 9)
APSIPA Transactions on Signal and Information Processing     Open Access   (Followers: 9)
Archives of Electrical Engineering     Open Access   (Followers: 13)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 8)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 28)
Bioelectronics in Medicine     Hybrid Journal  
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 19)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 36)
Biomedical Instrumentation & Technology     Hybrid Journal   (Followers: 6)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 12)
BULLETIN of National Technical University of Ukraine. Series RADIOTECHNIQUE. RADIOAPPARATUS BUILDING     Open Access   (Followers: 1)
Bulletin of the Polish Academy of Sciences : Technical Sciences     Open Access   (Followers: 1)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 47)
China Communications     Full-text available via subscription   (Followers: 8)
Chinese Journal of Electronics     Hybrid Journal  
Circuits and Systems     Open Access   (Followers: 15)
Consumer Electronics Times     Open Access   (Followers: 5)
Control Systems     Hybrid Journal   (Followers: 266)
Edu Elektrika Journal     Open Access   (Followers: 1)
Electrica     Open Access  
Electronic Design     Partially Free   (Followers: 105)
Electronic Markets     Hybrid Journal   (Followers: 7)
Electronic Materials Letters     Hybrid Journal   (Followers: 4)
Electronics     Open Access   (Followers: 86)
Electronics and Communications in Japan     Hybrid Journal   (Followers: 10)
Electronics For You     Partially Free   (Followers: 92)
Electronics Letters     Hybrid Journal   (Followers: 26)
Elkha : Jurnal Teknik Elektro     Open Access  
Embedded Systems Letters, IEEE     Hybrid Journal   (Followers: 51)
Energy Harvesting and Systems     Hybrid Journal   (Followers: 4)
Energy Storage Materials     Full-text available via subscription   (Followers: 3)
EPJ Quantum Technology     Open Access  
EURASIP Journal on Embedded Systems     Open Access   (Followers: 11)
Facta Universitatis, Series : Electronics and Energetics     Open Access  
Foundations and Trends® in Communications and Information Theory     Full-text available via subscription   (Followers: 6)
Foundations and Trends® in Signal Processing     Full-text available via subscription   (Followers: 10)
Frequenz     Hybrid Journal   (Followers: 1)
Frontiers of Optoelectronics     Hybrid Journal   (Followers: 1)
Geoscience and Remote Sensing, IEEE Transactions on     Hybrid Journal   (Followers: 189)
Haptics, IEEE Transactions on     Hybrid Journal   (Followers: 4)
IACR Transactions on Symmetric Cryptology     Open Access  
IEEE Antennas and Propagation Magazine     Hybrid Journal   (Followers: 97)
IEEE Antennas and Wireless Propagation Letters     Hybrid Journal   (Followers: 77)
IEEE Journal of Emerging and Selected Topics in Power Electronics     Hybrid Journal   (Followers: 46)
IEEE Journal of the Electron Devices Society     Open Access   (Followers: 9)
IEEE Journal on Exploratory Solid-State Computational Devices and Circuits     Hybrid Journal   (Followers: 1)
IEEE Power Electronics Magazine     Full-text available via subscription   (Followers: 66)
IEEE Transactions on Antennas and Propagation     Full-text available via subscription   (Followers: 70)
IEEE Transactions on Automatic Control     Hybrid Journal   (Followers: 56)
IEEE Transactions on Circuits and Systems for Video Technology     Hybrid Journal   (Followers: 19)
IEEE Transactions on Consumer Electronics     Hybrid Journal   (Followers: 40)
IEEE Transactions on Electron Devices     Hybrid Journal   (Followers: 19)
IEEE Transactions on Information Theory     Hybrid Journal   (Followers: 26)
IEEE Transactions on Power Electronics     Hybrid Journal   (Followers: 71)
IEEE Transactions on Signal and Information Processing over Networks     Full-text available via subscription   (Followers: 12)
IEICE - Transactions on Electronics     Full-text available via subscription   (Followers: 12)
IEICE - Transactions on Information and Systems     Full-text available via subscription   (Followers: 5)
IET Cyber-Physical Systems : Theory & Applications     Open Access   (Followers: 1)
IET Microwaves, Antennas & Propagation     Hybrid Journal   (Followers: 35)
IET Nanodielectrics     Open Access  
IET Power Electronics     Hybrid Journal   (Followers: 46)
IET Smart Grid     Open Access  
IET Wireless Sensor Systems     Hybrid Journal   (Followers: 18)
IETE Journal of Education     Open Access   (Followers: 4)
IETE Journal of Research     Open Access   (Followers: 11)
IETE Technical Review     Open Access   (Followers: 13)
IJEIS (Indonesian Journal of Electronics and Instrumentation Systems)     Open Access   (Followers: 3)
Industrial Electronics, IEEE Transactions on     Hybrid Journal   (Followers: 58)
Industry Applications, IEEE Transactions on     Hybrid Journal   (Followers: 24)
Informatik-Spektrum     Hybrid Journal   (Followers: 2)
Instabilities in Silicon Devices     Full-text available via subscription   (Followers: 1)
Intelligent Transportation Systems Magazine, IEEE     Full-text available via subscription   (Followers: 13)
International Journal of Advanced Research in Computer Science and Electronics Engineering     Open Access   (Followers: 18)
International Journal of Advances in Telecommunications, Electrotechnics, Signals and Systems     Open Access   (Followers: 10)
International Journal of Antennas and Propagation     Open Access   (Followers: 11)
International Journal of Applied Electronics in Physics & Robotics     Open Access   (Followers: 5)
International Journal of Computational Vision and Robotics     Hybrid Journal   (Followers: 6)
International Journal of Control     Hybrid Journal   (Followers: 12)
International Journal of Electronics     Hybrid Journal   (Followers: 7)
International Journal of Electronics and Telecommunications     Open Access   (Followers: 13)
International Journal of Granular Computing, Rough Sets and Intelligent Systems     Hybrid Journal   (Followers: 2)
International Journal of High Speed Electronics and Systems     Hybrid Journal  
International Journal of Image, Graphics and Signal Processing     Open Access   (Followers: 14)
International Journal of Microwave and Wireless Technologies     Hybrid Journal   (Followers: 8)
International Journal of Nano Devices, Sensors and Systems     Open Access   (Followers: 12)
International Journal of Nanoscience     Hybrid Journal   (Followers: 1)
International Journal of Numerical Modelling: Electronic Networks, Devices and Fields     Hybrid Journal   (Followers: 4)
International Journal of Power Electronics     Hybrid Journal   (Followers: 24)
International Journal of Review in Electronics & Communication Engineering     Open Access   (Followers: 4)
International Journal of Sensors, Wireless Communications and Control     Hybrid Journal   (Followers: 10)
International Journal of Systems, Control and Communications     Hybrid Journal   (Followers: 4)
International Journal of Wireless and Microwave Technologies     Open Access   (Followers: 6)
International Transaction of Electrical and Computer Engineers System     Open Access   (Followers: 2)
JAREE (Journal on Advanced Research in Electrical Engineering)     Open Access  
Journal of Biosensors & Bioelectronics     Open Access   (Followers: 3)
Journal of Advanced Dielectrics     Open Access   (Followers: 1)
Journal of Artificial Intelligence     Open Access   (Followers: 10)
Journal of Circuits, Systems, and Computers     Hybrid Journal   (Followers: 4)
Journal of Computational Intelligence and Electronic Systems     Full-text available via subscription   (Followers: 1)
Journal of Electrical and Electronics Engineering Research     Open Access   (Followers: 24)
Journal of Electrical Bioimpedance     Open Access   (Followers: 2)
Journal of Electrical Engineering & Electronic Technology     Hybrid Journal   (Followers: 7)
Journal of Electrical, Electronics and Informatics     Open Access  
Journal of Electromagnetic Analysis and Applications     Open Access   (Followers: 7)
Journal of Electromagnetic Waves and Applications     Hybrid Journal   (Followers: 8)
Journal of Electronic Design Technology     Full-text available via subscription   (Followers: 6)
Journal of Electronics (China)     Hybrid Journal   (Followers: 4)
Journal of Energy Storage     Full-text available via subscription   (Followers: 4)
Journal of Engineered Fibers and Fabrics     Open Access  
Journal of Field Robotics     Hybrid Journal   (Followers: 2)
Journal of Guidance, Control, and Dynamics     Hybrid Journal   (Followers: 167)
Journal of Information and Telecommunication     Open Access   (Followers: 1)
Journal of Intelligent Procedures in Electrical Technology     Open Access   (Followers: 3)
Journal of Low Power Electronics     Full-text available via subscription   (Followers: 7)
Journal of Low Power Electronics and Applications     Open Access   (Followers: 9)
Journal of Microelectronics and Electronic Packaging     Hybrid Journal  
Journal of Microwave Power and Electromagnetic Energy     Hybrid Journal  
Journal of Microwaves, Optoelectronics and Electromagnetic Applications     Open Access   (Followers: 10)
Journal of Nuclear Cardiology     Hybrid Journal  
Journal of Optoelectronics Engineering     Open Access   (Followers: 4)
Journal of Physics B: Atomic, Molecular and Optical Physics     Hybrid Journal   (Followers: 28)
Journal of Power Electronics & Power Systems     Full-text available via subscription   (Followers: 11)
Journal of Semiconductors     Full-text available via subscription   (Followers: 5)
Journal of Sensors     Open Access   (Followers: 26)
Journal of Signal and Information Processing     Open Access   (Followers: 9)
Jurnal Rekayasa Elektrika     Open Access  
Jurnal Teknik Elektro     Open Access  
Jurnal Teknologi Elektro     Open Access  
Kinetik : Game Technology, Information System, Computer Network, Computing, Electronics, and Control     Open Access  
Learning Technologies, IEEE Transactions on     Hybrid Journal   (Followers: 12)
Magnetics Letters, IEEE     Hybrid Journal   (Followers: 7)
Majalah Ilmiah Teknologi Elektro : Journal of Electrical Technology     Open Access   (Followers: 2)
Metrology and Measurement Systems     Open Access   (Followers: 5)
Microelectronics and Solid State Electronics     Open Access   (Followers: 18)
Nanotechnology Magazine, IEEE     Full-text available via subscription   (Followers: 33)
Nanotechnology, Science and Applications     Open Access   (Followers: 6)
Nature Electronics     Hybrid Journal  
Networks: an International Journal     Hybrid Journal   (Followers: 5)
Open Electrical & Electronic Engineering Journal     Open Access  
Open Journal of Antennas and Propagation     Open Access   (Followers: 8)
Optical Communications and Networking, IEEE/OSA Journal of     Full-text available via subscription   (Followers: 15)
Paladyn. Journal of Behavioral Robotics     Open Access   (Followers: 1)
Power Electronics and Drives     Open Access   (Followers: 1)
Problemy Peredachi Informatsii     Full-text available via subscription  
Progress in Quantum Electronics     Full-text available via subscription   (Followers: 7)
Pulse     Full-text available via subscription   (Followers: 5)
Radiophysics and Quantum Electronics     Hybrid Journal   (Followers: 2)
Recent Advances in Communications and Networking Technology     Hybrid Journal   (Followers: 3)
Recent Advances in Electrical & Electronic Engineering     Hybrid Journal   (Followers: 9)
Research & Reviews : Journal of Embedded System & Applications     Full-text available via subscription   (Followers: 5)
Security and Communication Networks     Hybrid Journal   (Followers: 2)
Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of     Hybrid Journal   (Followers: 53)
Semiconductors and Semimetals     Full-text available via subscription   (Followers: 1)
Sensing and Imaging : An International Journal     Hybrid Journal   (Followers: 2)
Services Computing, IEEE Transactions on     Hybrid Journal   (Followers: 4)
Software Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 75)
Solid-State Circuits Magazine, IEEE     Hybrid Journal   (Followers: 13)
Solid-State Electronics     Hybrid Journal   (Followers: 9)
Superconductor Science and Technology     Hybrid Journal   (Followers: 2)
Synthesis Lectures on Power Electronics     Full-text available via subscription   (Followers: 3)
Technical Report Electronics and Computer Engineering     Open Access  
TELE     Open Access  
Telematique     Open Access  
TELKOMNIKA (Telecommunication, Computing, Electronics and Control)     Open Access   (Followers: 9)
Universal Journal of Electrical and Electronic Engineering     Open Access   (Followers: 6)
Visión Electrónica : algo más que un estado sólido     Open Access   (Followers: 1)
Wireless and Mobile Technologies     Open Access   (Followers: 6)
Wireless Power Transfer     Full-text available via subscription   (Followers: 4)
Women in Engineering Magazine, IEEE     Full-text available via subscription   (Followers: 11)
Електротехніка і Електромеханіка     Open Access  

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Similar Journals
Journal Cover
Industry Applications, IEEE Transactions on
Journal Prestige (SJR): 1.02
Citation Impact (citeScore): 4
Number of Followers: 24  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0093-9994
Published by IEEE Homepage  [191 journals]
  • IEEE Industry Applications Society
    • Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • IEEE Transactions On Industry Applications
    • Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Information for Authors
    • Abstract: Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Recognition of 2018 Transactions and Magazine
           Papers Reviewers
    • Authors: Thomas A. Nondahl;
      Pages: 1041 - 1071
      Abstract: The publication offers a note of thanks and lists its reviewers.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Seamless Operation and Control of Single-Phase Hybrid PV-BES-Utility
           Synchronized System
    • Authors: Shailendra Kumar;Bhim Singh;
      Pages: 1072 - 1082
      Abstract: This paper presents the control of a single-phase photovoltaic (PV) battery energy storage (BES) based hybrid system with seamless transfer and power quality (PQ) improvement features. The PV-BES based single-phase system provides uninterruptable power to the dedicated nonlinear loads even under utility outage by transferring smoothly to the islanding. Therefore, the smooth transfer from the grid integrated operation to the islanding and vice versa provides high reliability of the system than the conventional system. To control the proposed synchronized system in the grid integrated mode, a learning quantization (LQ) based current control with PV feed-forward (PVFF) loop is used. The LQ current control extracts the net active component of load current. Moreover, PVFF is included in the LQ control to reflect the PV power contribution in the utility, which also improved the fast tracking ability of the proposed control under variable climate conditions. In islanding operation, the load voltage is regulated by the voltage control. The effectiveness of the LQ-based current control for a single-phase PV-BES-utility synchronized system is demonstrated through the simulated as well as experimental results.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Replacing Diesel Generators With Hybrid Renewable Power Plants: Giglio
           Smart Island Project
    • Authors: Fabio Massimo Gatta;Alberto Geri;Stefano Lauria;Marco Maccioni;Francesco Palone;Pierluigi Portoghese;Luca Buono;Andrea Necci;
      Pages: 1083 - 1092
      Abstract: The use of diesel generators to supply electricity to small remote islands is both costly and environmentally troublesome. On the other hand, small island networks pose peculiar stability and reliability problems when renewable energy sources are added. This paper regards the installation of a hybrid power plant (photovoltaic, plus lithium battery and synchronous condenser) in Giglio island, to replace existing diesel units. This paper discusses the general overview of the project and presents steady-state and dynamic simulations of the proposed energy system. Results evidence the advantages of the proposed Giglio hybrid power plant over existing diesel generators in terms of reduction of both pollution and energy costs, also allowing to fulfill the N-1 network security criterion. At the same time, results underline the need to install a properly sized flywheel in order to assure the stability of supply.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Root Cause Analysis of Over-Current Ground Relay Tripping During
           Energizing Parallel Autotransformers
    • Authors: Yunfei Wang;Xiaodong Liang;Michael Jackman;Hooman Erfanian Mazin;
      Pages: 1093 - 1105
      Abstract: In this paper, the root cause analysis of excessive zero-sequence currents is conducted when energizing parallel autotransformers in a power system. The studied system is a large international airport in Canada, where its power is supplied by both utility and local distributed generation (DG) feeding the load through two parallel autotransformers. Recent field records indicated that when the utility, local generators and the first autotransformer were in operation, and the second autotransformer was already energized from its low voltage side, at this moment, closing the circuit breaker on the high voltage side of the second autotransformer caused rich third and ninth order harmonic currents and the subsequent over-current ground relay (51G) tripping. Through this research, it is determined that the root cause of the problem is the saturation of the two autotransformers. The PSCAD/EMTDC simulation is conducted for the system, and the simulation model is benchmarked using field measurement data. Two methods are developed in this paper to calculate the maximum RMS zero-sequence current flowing through the two autotransformers: 1) an analytical based simplified equivalent circuit method and 2) a curve fitting based mathematical equation method. The solutions to prevent misoperation of the ground relay are proposed and their effectiveness is validated.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Adaptive Active Power Sharing Techniques for DC and AC Voltage Control in
           a Hybrid DC/AC Microgrid
    • Authors: Ángel Navarro-Rodríguez;Pablo García;Ramy Georgious;Jorge García;
      Pages: 1106 - 1116
      Abstract: This paper deals with the ac and dc dynamic voltage control in a hybrid dc/ac microgrid (MG) with central and distributed battery energy storage systems (BESSs), applying a power sharing mechanism between the different devices in the MG. The MG is composed by a multiport transformation center and two fixed frequency three phase ac nanogrids (NGs) coupled to a dc bus through three-phase power electronic converters. The system pursues to minimize the dependence on the utility grid and the stress in the MGs central BESS, while increasing the power handling capability and the overall system stability during islanding condition. In order to approach the proposed aim, two main concerns are studied in this paper: An adaptive power sharing mechanism between the dc bus and the ac NGs for dc voltage control, and the design and implementation of an ac dynamic local voltage compensator based on distributed energy storage system. The proposed techniques are validated through simulations and experimental results.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Characterization of Phase-Angle Jump in Radial Systems Using Incremental
           Voltage Phasors
    • Authors: Ángela Espín-Delgado;Juan Ramón Camarillo-Peñaranda;Gustavo Ramos;
      Pages: 1117 - 1125
      Abstract: A methodology for characterizing the phase-angle jump associated with voltage sags in radial systems using incremental voltage quantities is presented in this paper. The incremental voltage phasor is defined as the difference between the pre-fault and the during-fault voltage phasors at the point of common coupling. The characteristics of this phasor are stated for different fault conditions as a function of system impedances. Both fault impedance and source neutral grounding impedance are considered in the analysis. Furthermore, the vector representation of phasors and impedance diagrams are employed as a graphical aid for understanding the incremental quantities behavior as a function of the system parameters. An algorithm for fault classification is also presented. Finally, the theoretical analysis is confirmed using real data provided by the Department of Energy and the Electric Power Research Institute. The results of this paper can be useful in future works for fault classification and fault location.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • On the Interconnections of HV–MV Stations to Global Grounding
    • Authors: Maria Luisa Di Silvestre;Luigi Dusonchet;Salvatore Favuzza;Stefano Mangione;Liliana Mineo;Massimo Mitolo;Eleonora Riva Sanseverino;Gaetano Zizzo;
      Pages: 1126 - 1134
      Abstract: The interconnection of grounding systems of HV-MV stations via the armors of medium voltage cables, is herein analyzed to verify the effects on touch voltages in ground-fault conditions. The major contributions of this paper are two: the analysis of the impact of an HV ground-fault on a global grounding system (GGS), and the analysis of the parameters that may affect safety due to the interconnection between HV-MV stations and the GGS. The authors have analyzed cases when the connection of an HV-MV station to a GGS improves safety, and then may introduce hazards under ground-fault conditions. Two main issues are herein discussed: 1) the transfer of dangerous voltages to substations, due to ground-faults occurring at the HV-MV station; and 2) the reduction in the magnitude of the ground potential rise caused by ground-fault conditions at substations, due to the connection of their ground grids to the HV-MV station's grounding system. This paper, by examining various grid configurations, demonstrates that in some instances the inclusion of HV-MV stations in the GGS may reduce the level of protection against touch voltages, and that this depends on the following elements: the number of MV lines fed by the faulted station, the number of MV-LV substations per line, the value of the ground resistance of the substations, and the distance between the substations. This paper has practical relevance for both utilities distribution systems and industrial facilities supplied by the MV power grid.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Real-Time Life-Cycle Assessment of High-Voltage Circuit Breakers for
           Maintenance Using Online Condition Monitoring Data
    • Authors: Payman Dehghanian;Yufan Guan;Mladen Kezunovic;
      Pages: 1135 - 1146
      Abstract: Life-cycle assessment of high-voltage (HV) circuit breakers (CB) in transmission systems, if efficiently done, can lead to an optimal decision on when, where, and how to perform maintenance. This paper elaborates a new approach on the identification of CB's deterioration/recovery states, i.e., the so-called life-cycle assessment, using its control circuit condition monitoring data. Reliability-oriented performance indicators, which can assess the condition of different physical parts of an HV CB in real time, are introduced first. Then, a quantitative methodology to define the probability of the CB falling into each class of deterioration/recovery states, i.e., healthy, vulnerable, troubled, and failed, is proposed. Using this approach, maintenance decisions can be effectively made on different parts of an HV CB, the impact of maintenance can be quantified, and system-wide maintenance optimization with respect to the condition-based distinction of CBs can be made possible. Field condition monitoring data recorded at different time intervals during the CB operation is utilized to evaluate the applicability and effectiveness of the proposed approach.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Smart Inverter Volt-Watt Control Design in High PV-Penetrated Distribution
    • Authors: Mahsa Ghapandar Kashani;Maziar Mobarrez;Subhashish Bhattacharya;
      Pages: 1147 - 1156
      Abstract: Advanced control techniques such as volt-watt and volt-VAR control have been developed for high integration of distributed renewable energy, such as photovoltaic (PV) resources, on an electric distribution system. However, designing these control parameters, which yields the best results in the system, is complicated and depends on feeder conditions. This paper proposes a method to properly design the volt-watt control parameters in smart PV inverters to increase the benefit of their control action. The intention of this control design is to mitigate the voltage violations in a high PV-penetrated distribution feeder, while evenly distributing the weight of energy curtailment among all PV systems. Test results are provided from simulation-only scenarios and a hardware-in-the-loop test platform.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Cooperative Operation of DG Inverters and a RIHAF for Power Quality
           Improvement in an Integrated Transformer-Structured Grid-Connected
    • Authors: Mingmin Zhang;Yong Li;Fang Liu;Wenguo Li;Yanjian Peng;Wenhua Wu;Yijia Cao;
      Pages: 1157 - 1170
      Abstract: Harmonics in microgrids have attracted intensive power quality concern. It is analyzed in this paper that both currents in the voltage-controlled DG inverter side and the main grid side are easily involved in harmonic distortion due to nonlinear loads and background harmonics. To deal with this issue, a cooperative operation strategy for the DG inverters and a reactor-integrated hybrid active power filter (RIHAF) are proposed based on an integrated transformer-structured grid-connected microgrid. First, for the purpose of cost reduction and covering space saving, an integrated transformer based on a reactor integration technique (RIT) is conceived and the principle of the RIT is illustrated. To improve the current quality in the DG inverter side, a harmonic impedance reinforcement control method is employed to enhance the harmonic rejection performance of the voltage-controlled DG inverter. Besides, taking advantage of the integrated transformer, a RIHAF is proposed to suppress the current harmonics in the main grid side. Detailed simulation results show that current harmonics in both the DG inverter side and the main grid side can be simultaneously suppressed with the proposed cooperative operation strategy. Finally, experimental results from a scaled-down integrated transformer-structured microgrid platform are presented to verify the effectiveness of the RIT and the proposed cooperative operation strategy.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Development of Community Grid: Review of Technical Issues and Challenges
    • Authors: Sebastian P. Rosado;Shafiuzzaman K. Khadem;
      Pages: 1171 - 1179
      Abstract: The concept of a community grid is presented here. It involves the distribution grid and an increased use of renewable energy coming from distributed resources along with consumer/prosumer engagement in the energy trading mechanism. The possible operation and management with energy trading flexibility are briefly outlined. Under such scenario, the classical operation of the distribution grid is challenged by the issues brought about by the large penetration level of the new energy resources. This paper presents a status review of the technical issues that may appear under the community grid scenario. Building up on these surveyed issues, this paper also reviews and discusses approaches to solutions, which are required in order to make the community grid highly renewable and sustainable.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Two-End Traveling Wave Fault Location System for MV Cables
    • Authors: Eleonora Riva Sanseverino;Vincenzo Li Vigni;Antonio Di Stefano;Roberto Candela;
      Pages: 1180 - 1188
      Abstract: In this paper, a new low-cost device is proposed for fault location in power distribution system. The device is part of a system that should include several units installed in couples at the two ends of medium voltage (MV) cable lines. Their low cost justifies a widespread installation of these devices, moreover other functionalities could be considered so as to enrich the potential of the system for MV cables monitoring and asset management. The system exploits a two-end traveling wave technique, low complexity, and low-cost solutions both for the analog front end as well as for the communication infrastructure. A LoRa network is indeed considered as wireless modulation technique perfectly suited when communication links with three characteristics are needed: low power, low bit rate, and long range. This paper shows the device that has been set up in Prysmian Electronics with some experimental phases showing the effectiveness of the proposed solution and the further developments expected.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • $3phi$ +Interconnected+PV+Systems&rft.title=Industry+Applications,+IEEE+Transactions+on&rft.issn=0093-9994&;&rft.aufirst=Saleh&;">On the Performance of the Frame-Angle Controller for $3phi$ Interconnected
           PV Systems
    • Authors: Saleh A. Saleh;
      Pages: 1189 - 1201
      Abstract: This paper presents the development and performance of a controller for photovoltaic (PV) systems that are gridconnected through a 3φ wavelet modulated (WM) dc-ac power electronic converter (PEC). The proposed controller is designed using decoupled current control loops, which have the d - q-axis components of the currents injected to the grid, as their inputs. The outputs of this controller are command values for the d - qaxis components of the voltages produced by a 3φ WM dc-ac PEC (vId* and vIq*). The values of vId* and vIq* are used to determine the required angleϑ, which aligns the frame spanned by the actual d - q-axis components of the voltages produced by the controlled 3φ WM dc-ac PEC (vId and vIq). The adjustments of ϑ allow changing the phase angles of sinusoidal reference signals used to generate the wavelet modulation switching pulses. The proposed controller is implemented for performance testing using a 15 kW ac module PV system that is interconnected through a 3φ, 6-pulse, WM dc-ac PEC. The performance of the frame-angle controller is tested for different changes in the power delivered to the grid and system parameters. Test results demonstrate stable, fast, and accurate control actions that are complimented by negligible sensitivity to levels of power delivery to the grid, as well as variations in system parameters.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Modeling for Series Arc of DC Circuit Breaker
    • Authors: Yong-Jung Kim;Hyosung Kim;
      Pages: 1202 - 1207
      Abstract: In electric distribution systems, a series arc occurs when a load and a power source are disconnected from a connector such as a circuit breaker, a socket-plug, or a coupler. In dc systems, the arc is not extinguished unless the arc current decreases to zero. Sustaining plasma arc current can cause huge fire disasters. To cope with the arc faults in dc systems, the characteristics of the arc should be analyzed. However, a clear analysis method has not been suggested. This paper analyzes characteristics of a series-breaking arc in a dc circuit breaker in three operation phases: initiation, sustenance, and extinguishment. Based on the three operation characteristics, a series-breaking arc model is proposed and evaluated through experiment.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Cost-Effective Solution for Clearing High-Impedance Ground Faults in
           Overhead Low-Voltage Lines
    • Authors: Massimo Mitolo;Rossano Musca;Gaetano Zizzo;
      Pages: 1208 - 1213
      Abstract: Downed distribution conductors in overhead distribution systems may not be a concern for equipment but greatly challenge the safety of persons, as well as the integrity of properties. Standard overcurrent protective devices may not be able to detect the magnitudes of currents resulting from high-impedance ground faults. Sophisticated relays able to detect high-impedance ground faults have been available to electric utilities. However, their implementation is rather uncommon, especially in developing countries, most likely due to their costs. In this paper, the authors formalize the problem, and propose a possible cost-effective solution for low-voltage overhead lines with neutral wire. This solution consists of a metal hook underneath the line conductors, attached to the pole and connected to the neutral wire. In the case of a falling line, the hook would be contacted and a line-to-neutral short circuit would occur; this would positively activate existing standard overcurrent devices, which can therefore disconnect the supply. Costs related to the installation of the device to existing overhead lines are herein analyzed. The effectiveness of the proposed solutions for two different voltage levels (400 V in European countries and 240 V in the USA) is also discussed.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Survivability of Prime-Mover Powered Inverter-Based Distributed Energy
           Resources During Microgrid Islanding
    • Authors: Jongchan Choi;Amrit Khalsa;David A. Klapp;Surya Baktiono;Mahesh S. Illindala;
      Pages: 1214 - 1224
      Abstract: Inverter-based distributed energy resources (DERs) can supply high-quality ac power in a microgrid due to their fast dynamic response. To achieve high reliability in an islanded microgrid, they are normally operated as voltage-controlled sources. However, the net load supplied by voltage-controlled inverter-based DERs can exceed their rated capacity, particularly during their transition from the grid-connected operation mode. Therefore, a comprehensive analysis of the DER survivability for overload conditions is crucial. Several experimental tests were conducted at the Consortium for Electric Reliability Technology Solutions Microgrid Testbed on the prime-mover powered inverter-based DER for learning about its survivability during overload conditions. In this paper, a thorough investigation of the inverter-based DER's survivability is carried out based on the prime-mover stalling phenomenon. Analytical expressions are derived for key design parameters of load-shedding algorithms, such as time-to-threshold frequency, maximum time delay, and maximum survivability time. The theoretical estimates are validated with the results obtained from the experimental testing. Furthermore, the minimum load-shedding estimate is determined for any prime-mover powered inverter-based DER to survive a transient overload condition.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • $d-q$ +Framework,+and+Demonstration&rft.title=Industry+Applications,+IEEE+Transactions+on&rft.issn=0093-9994&;&rft.aufirst=Baoyun&;Aditya+N.+Ghule;Daniel+C.+Ludois;">High Torque Density Macro-scale Electrostatic Rotating Machines:
           Electrical Design, Generalized $d-q$ Framework, and Demonstration
    • Authors: Baoyun Ge;Aditya N. Ghule;Daniel C. Ludois;
      Pages: 1225 - 1238
      Abstract: The use of advanced dielectric liquids and manufacturing techniques for enhanced surface area per unit volume, along with other multiplicative gains, is enabling macro-scale electrostatic machines with competitive torque densities. This emergence prompts the need for circuit modeling-that guides machine design and drive controls-rooted in the canon of well-established electromagnetic machinery practices. In this study, prior dielectric and manufacturing innovations are combined with a newly developed unified electrostatic machine d-q-axis framework to form a machine that demonstrates industrial utility. Design, equivalent circuits, and performance are validated by an experimental prototype intended for low-speed direct-drive servo actuators. A prototype electrostatic machine was constructed entirely of aluminum and printed circuit boards, and possesses active material torque densities ≥1.4 N·m/kg and ≥2.65 N·m/L without the need for forced air or liquid cooling. Additional features include near zero loss at stall and low torque ripple.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Magnetically Geared Pseudo Direct Drive for Safety Critical Applications
    • Authors: Radu Stefan Dragan;Richard E. Clark;Essam Khalaf Hussain;Kais Atallah;Milijana Odavic;
      Pages: 1239 - 1249
      Abstract: This paper presents an investigation into the electromagnetic design and performance of a fault-tolerant (FT) magnetically geared pseudo-direct-drive (PDD) electrical machine for primary flight control surface electromechanical actuation. It is shown that a large number of combinations of high-speed rotor pole pairs, pole-piece numbers, and stator slot numbers exist, for which a duplex three-phase FT configuration can be realized. Furthermore, in addition to facilitating a lower mass solution, it is also shown that a PDD presents a significantly lower inertia referred to the screw when compared to direct-drive or mechanically geared motor solutions. The findings are validated on a prototype PDD, which has been designed and built to meet the requirements of a primary control surface electromechanical actuator.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Analysis of a Flux Reversal Machine With Quasi-Halbach Magnets in Stator
           Slot Opening
    • Authors: Kangfu Xie;Dawei Li;Ronghai Qu;Zixiang Yu;Yuting Gao;Yuan Pan;
      Pages: 1250 - 1260
      Abstract: Flux reversal permanent magnet (FRPM) machine, with magnets mounted on or inserted into the stator, is favorable for the direct drive applications. In this paper, an FRPM machine with Quasi-Halbach array magnets in stator slot opening is introduced. The operation principle of the proposed machine is presented, and the combination of stator and rotor slot number is given. Several key parameters, that are split ratio, stator and rotor slot opening ratio, magnet ratio, and magnet thickness are carefully investigated, while four proposed FRPM machines with 12 stator slots and 10, 11, 13, 14 rotor slots are optimized for better performance. Moreover, the proposed FRPM machine is compared with a conventional FRPM machine, the analysis results indicate that the torque density of proposed machine is 2.2 times that of the conventional FRPM machine under the same copper loss with almost the same magnet usage. Finally, a 12 stator slot/10 rotor slot FRPM prototype is built to verify the theoretical analysis.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Development of a Thermal Equivalent Circuit to Quantify the Effect of
           Thermal Paste on Heat Flow Through a Permanent Magnet Alternator
    • Authors: Mehmet Caglar Kulan;Nick J. Baker;
      Pages: 1261 - 1271
      Abstract: This paper describes the thermal modeling of a permanent magnet alternator (PMA). The principal focus is on, to investigate the effect of adding thermal paste into the machine end winding region. A thermal lumped parameter network is proposed to quantify the change in heat flow paths for a flange mounted alternator. The thermal model is implemented in Simulink, which allows many different heat paths to be easily combined. Since the addition of a thermal paste introduces new axial heat flow by conduction paths between the stator windings and frame, the developed thermal network considers the detailed heat flow paths in the PMA. The thermal network is extended to the machine frame and part of the mounting plate. It is shown that the axial heat flow has been improved by 5.6% for the PMA with the addition of the thermal paste. This in turn reduces winding temperature by around 10.5% at standstill dc tests. The model accuracy has been validated by performing finite-element analysis thermal simulations and experimental results.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Flux Observer Model for Sensorless Control of PM BLDC Motor With a Damper
    • Authors: Peng Li;Wei Sun;Jian-Xin Shen;
      Pages: 1272 - 1279
      Abstract: Sensorless control methods are commonly employed to derive the rotor position and speed information indirectly in permanent magnet (PM) brushless motor drives. Thereinto, the simple yet effective flux observer method is extensively applied in a wide range of applications. However, damper cage is sometimes employed in the rotor of certain PM brushless motor. Normally, high-order current harmonic components occur in such damper cage during operations. The introduction of these extra current contents can significantly hinder the performance of the conventional flux observer. By applying Park transformation, the fundamental harmonic components of stator phase currents, flux linkages, and voltages during steady-state operation, become constants under rotor synchronous reference frame, while the currents in the rotor damper cage are still alternating. In this paper, an improved flux observer method is proposed to filter the harmonic contents under the rotor synchronous reference frame for PM brushless motor with rotor damper cage. The validity and performance of the proposed flux observer are verified by both numerical analysis and experimental results.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Increasing the Energy Efficiency of Induction Machines by the Use of
           Grain-Oriented Magnetic Materials and Die Casting Copper Squirrel Cage in
           the Rotor
    • Authors: Vincent Mallard;Guillaume Parent;Cristian Demian;Jean-François Brudny;Aurélien Delamotte;
      Pages: 1280 - 1289
      Abstract: This paper deals with an induction machine whose squirrel cage is made of copper obtained by a die casting process. The major issue of this process is the thermal shock suffered by the laminations, leading to the deterioration of insulation coating as well as the generation of interbar currents, those currents being responsible for addition stray losses. This issue can be counteracted by using grain-oriented (GO) laminations on the rotor. In particular, the paper highlights that due to the specificity of the insulation coating of that kind of electrical steel, it does not suffer from the thermal shock. It is shown that using a squirrel cage made of copper combined to GO laminations in the rotor leads to a decrease of both core losses and stray load losses and an increase of the efficiency of 1.6%.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Influence of Rotor Tooth Shaping on Cogging Torque of Axial Flux-Switching
           Permanent Magnet Machine
    • Authors: Ju Hyung Kim;Yingjie Li;Emrah Cetin;Bulent Sarlioglu;
      Pages: 1290 - 1298
      Abstract: This paper proposes a rotor tooth shaping method to reduce the cogging torque of an axial flux-switching permanent magnet machine. The rotor tooth is shaped in different configurations, including constant, trapezoidal, asymmetrical, extended, and square shapes to evaluate the effects on cogging torque ripple minimization. A three-dimensional (3-D) finite-element analysis (FEA) is performed to compare the proposed shapes of the rotor tooth. Peak-to-peak cogging torque, fundamental flux linkage, loaded torque, and the total weight of teeth are compared using various rotor tooth angles. The simulation results show that overall minimum cogging torque is achieved by the extended shape of the rotor tooth. 3-D FEA results are also verified with experimental results.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Core Loss Estimation in Electric Machines With Flux-Controlled Core Loss
    • Authors: Burak Tekgun;Yilmaz Sozer;Igor Tsukerman;Parag Upadhyay;Steven Englebretson;
      Pages: 1299 - 1308
      Abstract: The complexity of core loss estimation is a serious challenge in the design of high-efficiency electric machines. Current estimation methods based on the Steinmetz equation and loss separation are not accurate enough, even at the rated conditions. This paper describes a loss estimation technique combining finite-element analysis (FEA) and actual core loss measurements. First, flux density waveforms in various parts of the electric machine are determined using FEA. Second, the same waveforms are generated in a wound toroidal core made of the same material as used in the machine. The loss is measured per unit mass, and then the total motor core loss is calculated by integrating the measured W/kg loss values for predefined sections of the motor. These estimation results are compared with those of the Bertotti method. The proposed procedure is shown to improve the accuracy of loss estimation.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Magnet Eddy Current Loss Reduction in Permanent Magnet Machines
    • Authors: Jie Ma;Z. Q. Zhu;
      Pages: 1309 - 1320
      Abstract: Magnet eddy current loss is very important for any types of permanent magnet (PM) machines, especially for high-speed PM machine since it increases significantly with rotating speed and has a great effect on the temperature of a magnet and, hence, the electromagnetic performance, as well as irreversible demagnetization of the magnet. In this paper, a new method is proposed to reduce the rotor PM eddy current loss. The auxiliary slots with an optimized size and position are proposed. By this mean, the asynchronous spatial harmonics caused by the armature reaction and the conventional slots can be partially decreased by the harmonics produced by the introduced auxiliary slots. It is proved that the rated on-load magnet eddy current loss can be reduced as much as 81.5% by this method, whereas the rated on-load torque is only decreased by 4.8% in the 3-slot/2-pole machine. In addition, it also shows that the proposed method could offer a better performance in a machine with relatively larger air gap length and it is also effective for other slot/pole combinations.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Model Predictive Control of a Switched Reluctance Machine for Guaranteed
           Overload Torque
    • Authors: Fang Qi;Alexander Stippich;Iliya Ralev;Annegret Klein-Hessling;Rik W. De Doncker;
      Pages: 1321 - 1331
      Abstract: Electric machines can be overloaded for short periods of time due to their inherently large thermal capacitance. The state-of-the-art overload strategies are often based on static characteristics of a machine. The real-time thermal condition is not considered in such strategies, leaving overload potential partially unused. This paper presents a model predictive overload strategy for a water-cooled automotive switched reluctance machine. The maximum allowed torque is predicted based on a real-time hot-spot temperature estimation, ensuring that the thermal capacitance of the machine is fully exploited. Due to the predictive nature of the algorithm, the peak torque production is inherently guaranteed over the prediction horizon. The proposed strategy is validated on a test bench. The proposed overload algorithm can be applied to other machine types as well.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Partial Discharges in Motor Fed by Inverter: From Detection to Winding
    • Authors: Cédric Abadie;Thibaut Billard;Thierry Lebey;
      Pages: 1332 - 1341
      Abstract: This paper reports non-intrusive partial discharge (PD) investigations on aeronautic and electric vehicle motors fed by inverter drive under variable environmental conditions. A representative test procedure and experimental setup based on operating aeronautic conditions are essential to ensure the accuracy and reliability of PD test on aircraft systems to make informed decisions on insulation system design choice. The aim of this paper is to demonstrate the feasibility of PD test of the insulation system on a different type of motor under such conditions, both electrically and environmentally. To do so, a study of the pressure influence on the frequency spectrum of discharges was carried out. This analysis defines the ability of the non-intrusive measurement system to detect PDs in equipment operating at low pressure. This paper also presents some tests on an industrial test bench to validate the ability of the non-intrusive test method and the associated numerical signal processing to detect PD in motors fed by PWM voltage. Then, an analysis is carried out on a motor to find out which voltage magnitude trigger PD events. The study helps to realize the benefits of using an inverter based test method to find the limits of the insulation system. It is shown that a representative insulation system performance picture could be drawn experimentally and used to enhance insulation design and manufacturing choices. The paper concludes with an analysis of results and thoughts about future work regarding advanced test procedure.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Analytical Power Limits Curves of High-Speed Synchronous Reluctance
    • Authors: Cristian Babetto;Giacomo Bacco;Nicola Bianchi;
      Pages: 1342 - 1350
      Abstract: The aim of this paper is to tackle the design of synchronous reluctance machines with transverse laminated rotor for high-speed applications by means of an analytical model. In high-speed applications, the mechanical design greatly affects the motor performance in terms of torque density and power factor. In fact, as the rated speed increases, the radial ribs thicknesses increase as well to ensure the rotor structural integrity against the centrifugal force. This increases the quadrature flux and, therefore, the rotor anisotropy gets worse. Hence, the optimal rotor design is the result of a compromise between mechanical and magnetic aspects. The purpose of this paper is twofold: First, to develop an analytical model that links the maximum average torque to the rated speed, and second, to determine the maximum power that can be generated by a specific rotor geometry. The analytical approach allows a fast motor design and analysis so that a rapid extrapolation of the results to different machine size is possible. Finite element analysis is used only to validate the final results.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Design of High Torque Density Multi-Core Concentrated Flux-Type
           Synchronous Motors Considering Vibration Characteristics
    • Authors: Min-Ro Park;Jae-Woo Jung;Doo-Young Kim;Jung-Pyo Hong;Myung-Seop Lim;
      Pages: 1351 - 1359
      Abstract: This paper proposes a novel structure for the concentrated flux-type synchronous motor (CFSM) in order to improve the torque density, as well as the vibration characteristics. First, the conventional surface-mounted permanent magnet synchronous motor as prototype for the electric booster in the brake system is investigated through tests. Then, the relationship between the vibration characteristics and the number of poles and slots is analyzed. Based on the analysis results, a pole-slot combination for an improved CFSM is determined to enhance the vibration characteristics. Furthermore, a novel structure for the improved motor that employs three different core shapes in the rotor is proposed to increase the torque density. As a result, the improved motor with excellent vibration characteristics as well as a high torque density is designed. Finally, experiments are conducted to verify the effectiveness and the feasibility of the proposed method.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Systematic Study on the Effects of Dimensional and Materials Tolerances
           on Permanent Magnet Synchronous Machines Based on the IEEE Std 1812
    • Authors: Narges Taran;Vandana Rallabandi;Dan M. Ionel;Ping Zhou;Mark Thiele;Greg Heins;
      Pages: 1360 - 1371
      Abstract: In the process of designing and manufacturing an electrical machine, a systematic study of dimensional and material tolerances is of the utmost importance. This paper proposes a systematic method by which the effect of design specification variations on permanent magnet (PM) synchronous machine performance may be identified and quantified. The method combines design of experiments techniques, open-circuit and short-circuit physical measurements, and virtual test simulations conducted based on the recently approved IEEE Std 1812 testing guide. Three case studies, two provided by a spoke-type PM radial field machine configuration, in two designs with different electromagnetic loading, and an axial flux PM machine are discussed. It is shown that based on the output performance, out of specification tolerances for magnet remanence, steel grade, as well as dimensional variables, and stator to rotor eccentricity, may be identified under certain conditions. It is also exemplified that the ratings, magnetic loading, and configuration of the machine play critical roles and should be thoroughly considered as part of the studies.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Research on Fast Design of Key Variables of Bearingless Flux-Switching
           Motor Based on Variable Structure Magnetic Network
    • Authors: Yangzhong Zhou;Fei Fang;Mengfei Zheng;
      Pages: 1372 - 1381
      Abstract: The bearingless flux-switching permanent magnet motor (BFSPMM) adopts the stator permanent magnet structure, which is beneficial to the heat dissipation of the permanent magnet and reduces the risk of demagnetization caused by the temperature rise of the permanent magnet. However, since BFSPMM adopts the double-salient structure, the design method of the traditional rotor permanent magnet type motor with sine wave back electromotive force cannot be directly applied. Thus, the design of the BFSPMM is complicated and time consuming. To this end, this paper proposes a method to quickly design the key parameters of the BFSPMM, such as optimum tooth width ratio, electromagnetic torque, winding coupled permanent magnet flux, suspension force, etc. First, in order to overcome the shortcoming of finite element time consuming, a new variable structure magnetic network model (VSMNM) of the BFSPMM is built considering the eccentricity of rotor. Second, the expressions of the optimal rotor-to-stator tooth width ratio and the coupling permanent magnet flux linkage in power winding are directly deduced based on the proposed VSMNM. Then, the electromagnetic torque is deduced based on the permanent magnet flux linkage, and the suspension force is deduced based on VSMNM. Finally, the fast design method proposed in this paper is verified to be effective by the finite-element analysis and the experimental results.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Modeling and Optimization of a Tubular Permanent Magnet Linear Motor Using
           Transverse-Flux Flux-Reversal Topology
    • Authors: Dingfeng Dong;Wenxin Huang;Feifei Bu;Qi Wang;
      Pages: 1382 - 1391
      Abstract: In this paper, a novel tubular transverse-flux flux-reversal linear motor for long stroke applications is proposed. The proposed motor not only has the low-cost advantage of the existing flux-reversal permanent magnet (PM) linear motor (PMLM) by combining both PMs and armature winding in short primary, but also address the problem of complicated structure in conventional tubular PMLM by using the manufacturing process of the rotary motor. First, in order to reduce circumferential magnetic flux leakage and improve the utilization ratio of PM, the motor structure with the alternating distribution of double N poles and double S poles in the circumferential direction is designed, and the operating principle of the motor is presented. Then, the equivalent magnetic circuit model of the unit motor is established to derive the expressions of the back electromotive force (EMF) and the electromagnetic thrust. Third, the equivalent two-dimensional (2-D) finite-element method (FEM) is used to optimize the structural dimensions and analyze the static characteristics including the back EMF, the detent force, and the thrust. Meanwhile, the three-dimensional FEM verify the validity of the equivalent 2-D FEM. Finally, the experimental results verify the validity and the correctness of the topology structure and the design method of the motor.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • An Enhanced Analytical Calculation of the Phase Inductance of Switched
           Reluctance Machines
    • Authors: Sufei Li;Shen Zhang;Cheng Gong;Thomas G. Habetler;Ronald G. Harley;
      Pages: 1392 - 1407
      Abstract: Accurate prediction of the phase inductance of switched reluctance machines (SRMs) is of crucial importance at the design stage because it is a key parameter to estimate the performance indices, such as the torque and loss. Instead of using the popular but time-consuming finite-element analysis (FEA) or the methods that require prior knowledge of magnetic fields from an FEA, such as function approximation and flux path methods, this paper proposes a novel fast and accurate analytical approach to determine the phase inductance of an SRM by solving the partial differential equations of magnetic potentials based on Maxwell's equations. In particular, an enhancement of the accuracy of the analytical model is accomplished by applying conformal mappings that deal with the non-radial/non-peripheral geometric structures when calculating the air-region permeance parameters. Moreover, a magnetic circuit network is applied to account for the steel saturation effects. The close agreement between the results of the proposed analytical method, FEAs and experimental measurements validate the analysis.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Comparative Study on Variable Flux Memory Machines With Parallel or Series
           Hybrid Magnets
    • Authors: Hao Hua;Z. Q. Zhu;Adam Pride;Rajesh Deodhar;Toshinori Sasaki;
      Pages: 1408 - 1419
      Abstract: Variable flux memory (VFM) permanent magnet (PM) machines exhibit an additional degree of freedom for control, i.e., PM magnetization state, and thus excellent flux controllability. Moreover, the hybrid PM topologies having variable PM (VPM) with low coercive force and constant PM (CPM) with high coercive force at the same time are employed to improve the torque density and the flux controllability. The parallel and series connections between the two different kinds of PMs are both feasible. Based on equivalent magnetic circuits, two-dimensional finite element analyses and experiments, the VFM machines with these two connection types are investigated and compared in this paper. The results reveal that the VPM with series-connected CPM is beneficial for more stable working point and higher torque density. A pair of VFM prototypes with parallel and series hybrid PMs are manufactured and tested to validate the analyses.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A New Perspective on the PM Vernier Machine Mechanism
    • Authors: Kangfu Xie;Dawei Li;Ronghai Qu;Xiang Ren;Manoj R. Shah;Yuan Pan;
      Pages: 1420 - 1429
      Abstract: Permanent magnet vernier (PMV) machines have attracted more and more attention for their merits of high torque density and simple structure. Also, the principle of electromechanical energy conversion is the most common way to investigate the PMV machine by calculating back electromotive force and electromagnetic torque. In this paper, a new perspective on the mechanism of PMV machines based on the Maxwell stress tensor method is presented to deepen the insight into the reason why the force on the rotor of a PMV machine is larger than that of an surface permanent magnet (SPM) machine. Based on the finite element analysis (FEA) method, three machines with exactly the same rotor are analyzed and compared, namely 24-slot/20-pole SPM, 12-slot/20-pole surface PMV, and 6-slot/20-pole split-tooth PMV machines. The radial and tangential flux densities and force distributions along the airgap are illustrated. The influence of pole ratio on the performance of PMV machines is also investigated. It is shown that the improvement of tangential flux density in the PMV machine plays a primary role in the higher torque density, which shows a promising way to improve the torque density of machines.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Shaft-to-Frame Voltage Mitigation Method by Changing Winding-to-Rotor
           Parasitic Capacitance of IPMSM
    • Authors: Seung-Tae Lee;Jun-Kyu Park;Chae-Lim Jeong;Se-Hyun Rhyu;Jin Hur;
      Pages: 1430 - 1436
      Abstract: Common-mode voltage by switching pattern of space vector pulsewidth modulation excites parasitic capacitance coupling in interior permanent magnet synchronous motors, and it finally causes a shaft-to-frame voltage. Among all parasitic capacitances, winding-to-rotor parasitic capacitance has the greatest effect on the shaft-to-frame voltage, which means the winding-to-rotor parasitic capacitance must be suppressed for noticeable mitigation of the shaft-to-frame voltage. This paper proposes two suppression methods by changing the stator winding-to-rotor and end winding-to-rotor capacitances. First, the modified winding shape is utilized for the suppression of stator winding-to-rotor capacitance. Second, a copper shield is applied to suppress the end winding-to-rotor parasitic capacitance. Finally, both the methods are applied together to mitigate the effect of the stator winding-to-rotor and end winding-to-rotor capacitances on the shaft-to-frame voltage.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Linear Permanent Magnet Synchronous Motor for Large Volume Needle-Free
           Jet Injection
    • Authors: Nick N. L. Do;Andrew James Taberner;Bryan P. Ruddy;
      Pages: 1437 - 1446
      Abstract: Needle-free jet injection allows delivery of liquid drugs through the skin in the form of a narrow fluid jet traveling at high speed, minimizing the risk of accidents. The use of a controllable actuator to drive this process has many advantages, but the voice coil actuators previously used are too large and heavy for practical use with common injection volumes (1 mL). We instead propose a compact slotless tubular linear permanent magnet synchronous motor design for jet injection. The design was determined by utilizing a semi-analytical electromagnetic modeling technique to predict the performance of any given motor design, an optimization scheme for the motor mass at a given power dissipation, and an automated routine for estimating cogging force using finite-element analysis. A prototype motor was constructed, with a nominal mass of 322 g, a stroke of 80 mm, and a target operating power of 1.2 kW; experimental data show that the motor constant is within 10% of the target, and that the cogging force is in close agreement with the model. Test ejection of water into a force sensor verified that the motor is fit for needle-free injection. The design methodology explained here shows the benefits to integrated design optimization of both the actuator and the load, particularly in systems that drive fluid pressure loads, and also opens the door to controllable injector designs for larger volumes.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Dynamical Modeling of Passively Levitated Electrodynamic Thrust
           Self-Bearing Machines
    • Authors: Joachim Van Verdeghem;Martin Lefebvre;Virginie Kluyskens;Bruno Dehez;
      Pages: 1447 - 1460
      Abstract: Topologies of electrodynamic thrust bearings and axial flux permanent magnet machines exhibit a significant number of similarities. Starting from this observation, this paper introduces a new self-bearing motor combining, within a single armature winding and through the same permanent magnets, both the passive electrodynamic axial levitation and motor functions. The rotor axial stabilization being achieved through passively induced currents, no sensor, controller, and power electronics related to the bearing function are required. In addition, an electromechanical model describing both the axial and spin dynamics of such a motor is presented. This set of six equations depends on 12 parameters whose determination can be performed through static finite element simulations or quasi-static experimental measurements. The model is linearized allowing us to study the local stability of this passive self-bearing motor around an operation point characterized by the rotor spin speed, as well as the external force and torque. The dynamic and quasi-static behaviors as well as the stable spin speed ranges are analyzed through a case study. Finally, a first experimental investigation dedicated to the validation of the operation principle as well as the dynamical model is performed.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Evaluation of Iron Loss Models in Electrical Machines
    • Authors: Zi-Qiang Zhu;Shaoshen Xue;Wenqiang Chu;Jianghua Feng;Shuying Guo;Zhichu Chen;Jun Peng;
      Pages: 1461 - 1472
      Abstract: In this paper, more than 10 different iron loss models are experimentally evaluated, which cover alternating and rotating fields, the influence of temperature, dc bias flux density and distorted flux density due to pulsewidth modulation inverter. Iron loss models considering alternating fields are evaluated by the measured results of a lamination ring specimen. The iron loss model considering the rotating field and the nonsinusoidal field are evaluated by the measured results of an electrical machine under different conditions. The iron loss models considering temperature influence are also evaluated by thermal analyses and experimental tests. Based on these comprehensive investigations, the iron loss models having the best prediction accuracy for each case are identified.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Novel Thermal Network Model Used for Temperature Calculation and
           Analysis on Brushless Doubly-Fed Generator With Winding Encapsulating
    • Authors: Xiaodong Jiang;Yue Zhang;Shi Jin;Fengge Zhang;Chris Gerada;
      Pages: 1473 - 1483
      Abstract: In recent years, magnetic-barrier rotor has been put forward for brushless doubly-fed generator (BDFG) application owing to its desirable performance, such as high power density and strong magnetic coupling ability. However, it also causes significant losses induced by harmonics and high temperature problem. Hence, it is a major challenge to evaluate Bref_DFG temperature rise fast and accurately. So far, aiming at magnetic-barrier rotor, there has been no accurate thermal network model established achieving this goal. In addition, wingding end encapsulating technology has been used for a few years and its heat dissipation potential is determined by the materials. Therefore, the application of novel material in winding encapsulating structure is desirable to improve the heat dissipation potential. In this paper, an equivalent thermal network model, thermal resistance models of magnetic-barrier rotor, and a winding encapsulating structure with novel materials are further established for thermal analysis. Subsequently, temperature distributions for BDFG components are also calculated by finite element method, while the results are compared with those by analytical method. The BDFG prototype is manufactured with experimental tests performed. The correctness of the equivalent thermal network models proposed in this paper is verified by the test results.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Dual Rotor Magnetically Geared Power Split Device for Hybrid Electric
    • Authors: Petr Chmelicek;Stuart D. Calverley;Radu S. Dragan;Kais Atallah;
      Pages: 1484 - 1494
      Abstract: This paper presents a theoretical and experimental investigation into a dual rotor magnetically geared power split device for hybrid electric drivetrains. It is shown that the modulation of magnetic field, created by rotor permanent magnets, by an array of ferromagnetic pole pieces results in two dominant space harmonics in the airgap adjacent to the stator. Thus, special attention is given to the design of the stator and the selection of the winding configuration, and the effects of air gap space harmonics on performance of the device are discussed. A full-scale prototype for a mid-sized passenger vehicle is designed, built, and tested, and the operation as a power split device is demonstrated and it is shown that efficiencies in excess of 94% can be achieved. Furthermore, torsional vibration attenuation by the proposed device is discussed and experimentally demonstrated on a purpose-built test rig.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Analysis of Stator/Rotor Pole Combinations in Variable Flux Reluctance
           Machines Using Magnetic Gearing Effect
    • Authors: Liren Huang;Z. Q. Zhu;Jianghua Feng;Shuying Guo;J. X. Shi;Wenqiang Chu;
      Pages: 1495 - 1504
      Abstract: The torque production of variable flux reluctance machines (VFRMs) is explained by the “magnetic gearing effect” in recent research. Based on this theory, this paper concludes the general principles for feasible stator/rotor pole selection and corresponding winding configuration for VFRMs. The influence of stator/rotor pole combination on torque performance is comprehensively investigated not only in terms of average torque and torque ripple, but also in terms of each single torque component. It is found that the synchronous torque is proportional to the fundamental rotor radial permeance component and has the dominant contribution in average torque for all the VFRMs. The stator slot number and rotor pole number should be close to each other to achieve the highest output torque. Meanwhile, the 6-stator-slot/(6i ± 2)-rotor-pole (6s/(6i ± 2)r) and their multiples are large torque ripple origins for VFRMs due to the large reluctance torque ripple. Also, it is proved that a lower stator slot number is preferable choice to obtain higher torque/copper loss ratio, whereas a higher stator slot number is more suitable for large machine scale scenario. Finally, the analyses and conclusions are verified by finite element analysis on the 6-, 12-, 18-, and 24-stator-slot VFRMs and by experimental tests on a 6s/7r and 6s/8r VFRMs.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Comparative Analysis of Variable Flux Reluctance Machines With Double- and
           Single-Layer Concentrated Armature Windings
    • Authors: Liren Huang;Z. Q. Zhu;Jianghua Feng;Shuying Guo;J. X. Shi;
      Pages: 1505 - 1515
      Abstract: In this paper, the variable flux reluctance machines (VFRMs) with double- and single-layer concentrated armature windings are comparatively analyzed. First, the single-layer winding is found to have an identical winding factor as a double-layer winding, but significantly larger peak value of magneto-motive force, which will result in severe local saturation in cores of VFRMs with single-layer winding. Then, based on the magnetic gearing effect and finite-element analysis, the electromagnetic performances of VFRMs with both winding types are compared. The VFRMs with single-layer winding are proved to be always lower in average torque, higher in torque ripple, larger in iron loss, and lower in efficiency than those with double-layer winding. Nevertheless, better fault-tolerance capability is achieved for a single-layer winding due to its physical separation between phases and larger phase self-inductance. Overall, the double-layer armature winding is the preferable choice for the VFRMs. Finally, a 6-stator-slot/4-rotor-pole VFRM with both double- and single-layer windings is prototyped for verification.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Double-Sided Stator Type Axial Bearingless Motor Development for Total
           Artificial Heart
    • Authors: Nobuyuki Kurita;Takeo Ishikawa;Naoki Saito;Toru Masuzawa;Daniel Lee Timms;
      Pages: 1516 - 1523
      Abstract: This paper proposed a bearingless motor that has tilt control function and clarified its fundamental characteristics as a magnetically suspended motor and magnetically suspended pump. The rotor has eight permanent magnets (PMs) on each side (16 PMs in total). The two stators have 12 poles each with two types of concentrated windings. One is for motoring and axial control and the other is for tilt control. This bearingless motor has three degrees of freedom active positioning control. The theoretical analysis clarified operating principle and showed that the proposed motor could control translational motion, inclinational, and rotational movement independently. An experimental setup was fabricated, and the control performance of the self-bearing motor was also investigated. The fabricated prototype achieved a stable magnetically levitated rotation. In addition, the proposed axial self-bearing motor fabricated into a prototype of the magnetically suspended pump to investigate pump characteristics for a total artificial heart applications.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Design Optimization and Performance Investigation of Linear Doubly Salient
           Slot Permanent Magnet Machines
    • Authors: Yiming Shen;Zhiqiang Zeng;Qinfen Lu;Lijian Wu;
      Pages: 1524 - 1535
      Abstract: Novel linear doubly salient slot permanent magnet machines (LDSSPMMs) are investigated in this paper. First, the machine topology and operation principle are introduced, and the choices of feasible slot/pole combinations and winding configurations for three armature phases are discussed. Then, the 12 slots and 10/11/13/14 poles LDSSPMMs with double-layer (DL)/single-layer windings are globally optimized using genetic algorithm. The electromagnetic performances including flux linkage, back electromotive force (back EMF), detent force, and static force-current characteristics are comparatively studied using two-dimensional (2-D) finite-element analysis (FEA). It shows that 12 slots/13 poles (12s/13p) and DL winding are the optimal choices to provide higher thrust force as well as lower force ripple. Moreover, the risk of local irreversible demagnetization of PMs is analyzed, which only occurs at very limited corners of the PMs and can be eliminated by PM shaping. Furthermore, the electromagnetic performances between linear variable flux reluctance machines (LVFRMs), linear hybrid-excited slot PM machines, linear primary yoke PM machines, and LDSSPMMs are comparatively studied. It shows that LDSSPMM can provide much higher thrust force than LVFRM at the same copper loss. With the increase of copper loss, LDSSPMM exhibits better thrust force capability than other machines. Finally, a prototype of 12s/13p DL-LDSSPMM is manufactured and tested to validate the 2-D FEA predicted results.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Loss Minimization Control Strategy for Linear Induction Machine in Urban
           Transit Considering Normal Force
    • Authors: Dong Hu;Wei Xu;Renjun Dian;Yi Liu;
      Pages: 1536 - 1549
      Abstract: Linear induction machine (LIM) in urban transit suffers greatly from poor efficiency due to the large air-gap length and the end-effects, including both transversal edge- and longitudinal end-effects caused by the cut-open magnetic circuit and different width between primary and secondary. Besides, the unique normal force existing in LIM that could be as high as four times of the thrust would create undesired additional resistance force and power loss, bending of the guide way, and tire wear. Addressing these issues, this paper proposes a novel loss minimization control (LMC) strategy for LIM to reduce the steady-state loss and normal force simultaneously. First, an improved loss model of LIM is proposed on the basis of the analysis of LIM copper and core loss. Second, the LIM normal force including both attractive and repulsive components is modeled in the same manner as the loss model. Third, a novel loss minimization cost function is set up, based on which the optimal solution is obtained through both analytical and numerical approaches, and thus an improved LMC strategy is carried out to achieve the minimization of steady-state loss and normal force at the same time. The proposed method is comprehensively investigated on one 3-kW arc induction machine (one prototype for actual LIM), and its effectiveness is fully validated through both simulation and experimental results.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Dual-Stator Doubly Salient Electromagnetic Motor Driving System Utilizing
           a Nine-Switch Converter
    • Authors: Jiadan Wei;Taojing Zhang;Liwei Shi;Bo Zhou;
      Pages: 1550 - 1560
      Abstract: This paper proposes a novel nine-switch converter for the dual-stator doubly salient electromagnetic motor (DSDSEM) in the compact and high-reliable driving system with 25% reduction of active switches compared with the conventional dual converter. The operation principle and mathematics model of DSDSEM are introduced, and the constraint relations of nine-switch topology for DSDSEM are given on the basis of the characteristics analysis of a nine-switch converter, then the corresponding commutation principles are proposed. Simultaneously, the influence of the interactions between the coupled outputs of the nine-switch converter is analyzed emphatically in the phase current commutation procedure. Besides, the advanced angle control strategy combined with the nine-state control strategy is optimized to eliminate the side effects of the interactions for the nine-switch converter. Finally, the effectiveness and feasibility of the control strategy of the proposed driving system are verified by the simulation and experiment results.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Electrical Losses Minimization of Linear Induction Motors Considering the
           Dynamic End-Effects
    • Authors: Angelo Accetta;Maria Carmela Di Piazza;Massimiliano Luna;Marcello Pucci;
      Pages: 1561 - 1573
      Abstract: This paper proposes an original electrical losses minimization technique (ELMT) suitably devised for field-oriented controlled linear induction motor (LIM) drives, taking into consideration the LIM's dynamic end-effects. The proposed technique improves the very few approaches in the scientific literature dealing with ELMTs applied to LIMs in the following aspects: 1) it accounts for the LIM dynamic end-effects not only considering the variation of the LIM parameters with speed but also including the braking force caused by the end-effects in the ELMT formulation; and 2) it considers the iron losses. The proposed approach has been tested in numerical simulation and validated experimentally on a suitably developed test setup. Results show that the application of the proposed ELMT permits a consistent losses reduction of about 22% even at low speed (0.75 m/s), as well as an increase in the overall drive efficiency ranging from 18%, at rated constant flux, up to 24% with the ELMT.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Extending Operational Limit of IPMSM in Signal-Injection Sensorless
           Control by Manipulation of Convergence Point
    • Authors: Yong-Cheol Kwon;Joohyun Lee;Seung-Ki Sul;
      Pages: 1574 - 1586
      Abstract: This paper analyzes the convergence of signal-injection sensorless control (SISC) especially for heavily saturated interior permanent-magnet synchronous motors (IPMSMs). In the analysis, it is revealed that the harmonic inductance and the operating current variation are critical factors in determining the operational limit of SISC. The clear boundary of SISC for an IPMSM can be obtained through the proposed convergence analysis. Based on this analysis, a control algorithm is proposed to extend the operational limit of SISC. With the proposed method, the torque capability under SISC can be maximized. Simulations and experiments are performed to verify the proposed method.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Family of Y-Source DC/DC Converter Based on Switched Inductor
    • Authors: Yijie Wang;Wenli Jing;Yuping Qiu;Yuanyuan Wang;Xiangyuan Deng;Ke Hua;Benran Hu;Dianguo Xu;
      Pages: 1587 - 1597
      Abstract: A novel family of high-gain dc/dc converters based on Y-source impedance network is proposed in this paper providing novel solutions to high voltage gain applications, such as photovoltaic and fuel cell systems. Proposed converters combine Y-source with boost modules resulting in strong boost ability, continuous input current, and inrush current suppression. Design flexibility and joint earthing of input and source are inherited from conventional Y-source. Working principles are presented and accurate steady-state analysis is conducted by mathematical derivations, moreover, comparisons among proposed converters and other impedance networks highlight their excellent performance. Experimental results show good agreement with theoretical analysis and the high feasibility of the proposed converters.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Stability Analysis of SAPF by Viewing DFT as Cluster of BPF for Selective
           Harmonic Suppression and Resonance Damping
    • Authors: Yuxiao Zhang;Ke Dai;Xinwen Chen;Yong Kang;Ziwei Dai;
      Pages: 1598 - 1607
      Abstract: This paper addresses the stability analysis of a shunt active power filter (SAPF) with capacitive load for selective harmonic suppression and resonance damping. If the capacitive load current is measured as part of harmonic suppression current reference, the SAPF with conventional selective harmonic suppression would amplify the corresponding harmonic beyond the resonance frequency. Previous studies could not clearly explain this harmonic amplification phenomenon without the selective harmonic extraction model in stability analysis. By viewing the discrete Fourier transform (DFT) as a cluster of band-pass filter (BPF), the modeling process is taken into consideration and is well simplified. The stability condition for suppressing and damping each selected harmonic can be easily estimated with the help of Nyquist stability criterion or root locus method in different SAPF control scenarios. To avoid the instability and compensate the harmonic current, a novel combined control strategy of the SAPF is carried out to simultaneously suppress the harmonics whose frequencies are lower than the resonance frequency and mitigate the rest of the harmonics by a resonance damping method. Experiments have been performed to verify the effectiveness of the proposed strategy.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A State Estimator-Based Approach for Open-Circuit Fault Diagnosis in
           Single-Phase Cascaded H-Bridge Rectifiers
    • Authors: Dong Xie;Xinglai Ge;
      Pages: 1608 - 1618
      Abstract: The reliability of single-phase cascaded H-bridge rectifiers (SPCHBR) is regarded as one of the most important factors for achieving the improvement of the stability and availability of the single-phase power electronic traction transformer in the railway traction system. Accordingly, an open-circuit fault diagnosis approach for single transistor faults in the SPCHBR is proposed in this paper. The proposed diagnostic algorithm relies on the state estimator and normalized detection variables. Moreover, fault cell detection and fault transistor location can be implemented according to the characteristics of the voltage and current residuals. The proposed method requires no additional sensors and only the information from the control system. Furthermore, the diagnostic method has a fast diagnosis speed and robustness against false alarms under different operating conditions. Test results in the hardware-in-the-loop system have illustrated the validity and feasibility of the proposed diagnostic method.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • System Optimization of a High Power Density Non-Isolated Intermediate Bus
           Converter for 48 V Server Applications
    • Authors: David Reusch;Suvankar Biswas;Yuanzhe Zhang;
      Pages: 1619 - 1627
      Abstract: With the power architecture transition from a 12 to 48 V rack in modern data centers, there is an increased interest in improving 48 V power conversion efficiency and power density. In this paper, we will analyze system optimization for a 48-12 V non-isolated, fully regulated, intermediate bus converter (IBC) to maximize efficiency and power density. This includes detailed analyses on the impact of power semiconductor device, gate driver as well as an exhaustive treatise on the choice of the optimal inductor. The final experimental prototype, a fully regulated, digitally controlled, 720 W, five phase, GaN transistor-based 48-12 V buck IBC demonstrates exceptional efficiency and power density, respectively, exceeding 95% and 1000 W/in3.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Active Capacitor Voltage Balancing Control for Three-Level Flying
           Capacitor Boost Converter Based on Average-Behavior Circuit Model
    • Authors: Hung-Chi Chen;Che-Yu Lu;Wei-Hsiang Lien;Tien-Hung Chen;
      Pages: 1628 - 1638
      Abstract: This paper proposes an active voltage balancing control strategy for the three-level flying capacitor boost converter (FCBC). The average-behavior circuit model for the three-level FCBC is studied, and then, the relationship of control to output signals is presented to analyze the coupling effects between the capacitor voltage balancing and the output voltage regulation. In addition, classical proportional and proportional-integral controllers are used for the voltage balancing control loop and the output voltage regulating control loop, respectively. Finally, the proposed control algorithm is implemented in a commercial field programmable gate array platform. Some simulation and experimental results demonstrate that the proposed active control strategy is able to achieve the desired effects for the steady-state and transient responses.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Single-Phase Universal Active Power Filter Based on Four-Leg
           AC–DC–AC Converters
    • Authors: Phelipe Leal Serafim Rodrigues;Cursino Brandão Jacobina;Maurício Beltrão de Rossiter Corrêa;Italo Roger Ferreira Moreno Pinheiro da Silva;
      Pages: 1639 - 1648
      Abstract: This paper presents two universal active power filters (UAPFs) configurations using single-phase four-leg ac-dc-ac converters. The proposed topologies are used for disturbance compensation in the power supply, such as voltages sags/swells, and to compensate harmonic distortions in the current. The operation of the proposed configurations is compared with the conventional single-phase four-leg UAPF. The harmonic distortions, semiconductor losses, and average switching frequency are used as comparison parameters. Compared to the conventional configuration, the proposed topologies use a transformer with lower power, provide lower average switching, and reduced current total harmonic distortion (THD) and voltage weighted THD. The pulsewidth modulation (PWM) strategy was designed based on a space vector modulation technique, and a control system for the grid current and dc-link bus voltage regulation was also developed. Simulation and experimental results are presented showing the efficiency of the PWM and control strategies and validating the proposed topologies.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Distributed Control Technique for the Multilevel Cascaded Converter
    • Authors: Ping-Heng Wu;Yu-Chen Su;J.-L. Shie;Po-Tai Cheng;
      Pages: 1649 - 1657
      Abstract: In recent years, the modular multilevel cascaded converters (MMCCs) have attracted interest for potential applications in utility-scale photovoltaic and battery energy storage systems. However, the large numbers of cascaded modules increase the difficulty of implementation in a centralized control architecture. This paper presents a distributed control technique for three-phase MMCCs, which can significantly reduce complexity and increases the flexibility to expand the system. In addition, reference voltage analysis is performed to better understand the operation of the proposed method. Experimental results carried out on a seven-level star-connected cascaded converter are included to validate the proposed approach.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Modified PSPWM for a Five-Level Hybrid-Clamped Inverter to Reduce Flying
           Capacitor Size
    • Authors: Kui Wang;Zedong Zheng;Boran Fan;Lie Xu;Yongdong Li;
      Pages: 1658 - 1666
      Abstract: In order to reduce the size of high-voltage flying capacitors in a five-level hybrid-clamped inverter, a modified phase-shifted pulsewidth modulation (PWM) method is proposed in this paper. The four carrier waves are redistributed and the charge/discharge time of the high-voltage capacitor can be reduced. The only disadvantage of this PWM method is that the harmonic characteristic will become worse. However, no low-order harmonics is imported and most of the harmonics are around carrier frequency and multitimes the carrier frequency, which are very easy to be filtered. Simulation and experimental results are presented to demonstrate the effectiveness of this method.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Brief Discussion of Two Stability Improvement Methods for
           Wide-Operation-Range Flyback Converter With Peak-Current-Mode Control at
           Variable Frequency
    • Authors: Ching-Hsiang Cheng;Ching-Jan Chen;Shinn-Shyong Wang;
      Pages: 1667 - 1676
      Abstract: Recently, a flyback converter with universal serial bus power delivery (USB-PD) specification is widely used in low-power adaptor application. However, the wide output-voltage-range operation of USB-PD makes the stability issue of the flyback converter more severe. This paper provides a brief discussion of two stability improvement methods for the peak-current-mode-controlled flyback converter at variable frequency and completely interprets those detailed techniques. Simulation validates the performances of the two methods. Furthermore, a control circuit and a flyback converter are built for experimental validation of the two stability improvement methods. Finally, some comments are also summarized.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Active Gate Driver for SiC-MOSFET-Based PV Inverter With Enhanced
           Operating Range
    • Authors: Sayan Acharya;Xu She;Fengfeng Tao;Tony Frangieh;Maja Harfman Todorovic;Rajib Datta;
      Pages: 1677 - 1689
      Abstract: For photovoltaic (PV) inverter applications, the grid code mandates reactive power support to the grid, and the amount of reactive power injection may be limited by the voltage overshoot during the switching transients of a power device. For SiCMOSFET-based PV inverters, this problem is more pronounced since the voltage and current gradient during switching transitions are much higher than a Si-based power converters. During a cloudy day when the inverter has to operate at PV panels open-circuit voltage, it becomes harder to push higher reactive power support to the grid due to the current derating of the SiC-devices at the operating dc bus voltages to keep the device within its safe operating limits with low switching losses at all operating conditions. Slowing down the switching transient could be a remedy but this also increases the converter losses. This paper demonstrates an application of a dynamic gate resistance modulation technique to keep the SiC-device within its safe operating limits while maintaining a low switching loss with minimum voltage and current overshoots. This helps to inject more power to the grid with at higher dc bus voltages without enhancement of the thermal management system. The proposed implementation also works equally well at high junction temperatures (up to Tj = 150 °C), which further increases the operating range of the PV inverter.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Simplified Carrier-Based Modulation Scheme for Three-Phase Three-Switch
    • Authors: Janamejaya Channegowda;Najath Abdul Azeez;Sheldon S. Williamson;
      Pages: 1690 - 1697
      Abstract: The three-phase three-switch (TPTS) converter has been used as the rectifier front-end stage for telecom power supplies. The space vector (SV)-based modulation technique has been the preferred choice for the operation and control of the TPTS converter. This paper introduces a simplified carrier-based modulation scheme, which can be implemented on inexpensive digital controllers without dealing with complex trigonometric equations. A comprehensive comparison between the traditional SV modulation scheme and the proposed carrier-based technique is presented with respect to the resource utilization on a digital controller. The procedure followed to obtain the carrier wave used in the proposed modulation scheme is explained. A 1 kW hardware prototype was built to validate the modulation scheme.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Universal Input AC Three-Phase Power Factor Correction With Adaptive
           Intermediate Bus Voltage to Optimize Efficiency
    • Authors: Hamidreza Hafezinasab;Wilson Eberle;Deepak S. Gautam;Chris Botting;
      Pages: 1698 - 1707
      Abstract: This paper proposes an adaptive intermediate bus voltage solution to optimize efficiency in a universal three-phase ac input (200-480 V) cascaded buck-follows-boost power factor corrected (PFC) converter with a 400-V dc output voltage. With this application and architecture, the output voltage of the boost converter needs to be higher than the peak ac input voltage to maintain PFC and regulation. The conventional approach would regulate the intermediate bus voltage to near 800-V dc; this allows for 480-V ac high line input, plus allowable overvoltage tolerance and margin for regulation, but it incurs heavy losses at low line input. This paper proposes to adaptively change the bus voltage between the boost and buck stages, based on the value of the ac input voltage, and the use of a relay to bypass the buck stage for low ac line input conditions in order to maximize efficiency. A loss analysis is included to show the significant loss savings and efficiency improvement using the proposed method. Experimental results are presented for a 5-kW silicon-carbide-based prototype. The proposed method demonstrates up to a 4.4 percentage point increase in efficiency (220-W decrease in loss) at low ac line input compared to the conventional PFC approach with an 800-V dc intermediate bus voltage.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Unidirectional Single-Phase AC–DC–AC Three-Level Three-Leg
    • Authors: Reuben Palmer Rezende de Sousa;Nustenil Segundo de Moraes Lima Marinus;Cursino Brandão Jacobina;Nady Rocha;
      Pages: 1708 - 1716
      Abstract: A unidirectional ac-dc-ac three-level three-leg converter is proposed in this paper. This converter is composed of a unidirectional neutral-point-clamped (NPC) leg and two bidirectional NPC legs. A bidirectional NPC leg is shared between rectifier and inverter sides. Compared with the two-level leg, the three-level leg presents voltage stress reduction on switches for the same dc-link voltage level and also allows a reduction in harmonic distortion for the same switching frequency. Suitable modeling, pulsewidth modulation, and control strategies of the system are presented. Also, a method for balancing dc-link capacitor voltages is shown. As the converter is unidirectional, the grid current and the generated voltage at the load side must be synchronized with the generated voltage at the grid side, which eliminates the zero-crossover distortion in the grid current caused by the use of diodes without the hysteresis control. Simulation and experimental results are also presented.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Adaptive Control Strategy for Ultracapacitor Based Bidirectional
           DC–DC Converters
    • Authors: Saichand Kasicheyanula;Vinod John;
      Pages: 1717 - 1728
      Abstract: Ultracapacitor (UC) based energy storage systems (ESS) are often operated as boost converters during discharging mode of operation. The control of such a system is typically performed using an outer voltage loop and inner current loop structure. Since UC stacks undergo wide voltage variation, it is desirable to have a control structure that accommodates system characteristics' variations, which allow deep discharge of UC stack. This paper proposes an adaptive control method with reduced settling time where the control gain parameters for outer voltage loop are obtained online in a UC-based bidirectional dc-dc converter. For this, analytical expressions for controller gains for a required bandwidth (BW) and response characteristics are obtained. Using these, simplification in gain expressions that is required for adaptive implementation is achieved. In this regard, the design and drawbacks of using fixed controller gain parameters for voltage loop are presented. The proposed control incorporates the effect of right-hand plane (RHP) zero on the voltage loop design, which constraints the control BW especially during deep discharges. The adaptive control adjusts the BW of the voltage loop according to the RHP zero location, thereby ensuring best performance possible for wide range of operating UC stack voltages. Such a formulation of controller gains results in a voltage feedforward method, which improves the control performance of the ESS, with an improvement in the settling time ranging from 10% to 50% depending on the operating UC stack voltage level. The proposed control is also compatible with load feedforward method and is found to have better performance as compared to the case when fixed controller gains with load feedforward is utilized. As a proof of concept, the proposed control is verified on an experimental setup with power level Po = 62 W, voltage level Vg = 26 V with the dc-dc converter switching at fsw = 100 kHz.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Dual-Input Single-Resonant Tank LLC Converter with Phase Shift Control for
           PV Applications
    • Authors: Seyed Milad Tayebi;Haibing Hu;Sam Abdel-Rahman;Issa Batarseh;
      Pages: 1729 - 1739
      Abstract: This paper proposes a dual-input LLC resonant converter that interfaces with two photovoltaic (PV) panels. The topology is a dual half-bridge LLC circuit with four active switches. This topology allows the two sources to share the same resonant tank for transferring energy to the load without the need for additional circuit components. A phase-shift pulsewidth modulation (PWM) control is employed to implement independent maximum power point tracking (MPPT) for each PV panel. Independent MPPT is achieved by varying the PWM phase shift of each source. Zero-voltage-switching is realized in all switches over the entire range of source voltage and load conditions. In addition, voltage stress across switches does not exceed the input PV voltage. A 500-W prototype was built to demonstrate the performance of the proposed topology. The input voltage range was selected between 25 and 50 V with an output voltage regulated at 220 V dc. Experimental results show that the proposed converter can achieve the peak efficiency of 95.8% while maintaining a wide input voltage range and implementing MPPT for each PV panel.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Startup Strategy With Constant Peak Transformer Current for Solid-State
           Transformer in Distribution Network
    • Authors: Jianning Sun;Liqiang Yuan;Qing Gu;Zhengming Zhao;
      Pages: 1740 - 1751
      Abstract: Solid-state transformer (SST) is widely used in many fields and it plays a key role in the development of energy internet. The startup strategy of SST adopted in distribution network has to be designed elaborately because in this application the requirement of functionality, flexibility, and expandability is very high. A number of researches for the startup process of SST were made and several solutions were proposed. In these solutions, the transformer current in the charging process was unable to be observed or controlled, leading to the lack of analytical basis in a startup strategy design. In order to make the charging process observable and controllable, the authors developed a mathematical model of this process. Based on the model, a new startup strategy is proposed to make the peak transformer current in the charging process a constant value. Cases with different conditions are analyzed, indicating that the strategy is insensitive to initial values. Experimental results are provided to validate the accuracy of the mathematical model and the effectiveness of the presented solution.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Structure-Reconfigurable Series Resonant DC–DC Converter With
           Wide-Input and Configurable-Output Voltages
    • Authors: Yanfeng Shen;Huai Wang;Ahmed Al-Durra;Zian Qin;Frede Blaabjerg;
      Pages: 1752 - 1764
      Abstract: This paper proposes a new series resonant dc-dc converter with four configurable operation states depending on the input-voltage and output-voltage levels. It suits well for the dc-dc stage of grid-connected photovoltaic systems with a wide-input voltage range and different grid voltage levels, i.e., 110/120 V and 220/230/240 V. The proposed converter consists of a dual-bridge structure on the primary side and a configurable half- or full-bridge rectifier on the secondary side. The root-mean-square (RMS) currents are kept low over a fourfold voltage-gain range; the primary-side mosfets and secondary-side diodes can achieve zero-voltage switching on and zero-current switching off, respectively. Therefore, the converter can maintain high efficiencies over a wide voltage gain range. A fixed-frequency pulsewidth-modulated control scheme is applied to the proposed converter, which makes the gain characteristics independent of the magnetizing inductance and thereby simplifies the design optimization of the resonant tank. The converter topology and operation principle are first described. Then, the characteristics, i.e., the dc voltage gain, soft switching, and RMS currents, are detailed before a performance comparison with conventional resonant topologies is carried out. Furthermore, the design guidelines of the proposed converter are also presented. Finally, the experimental results from a 500-W converter prototype verify the feasibility of the proposed converter.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Novel Three-Phase Transformerless H-8 Topology With Reduced Leakage
           Current for Grid-Tied Solar PV Applications
    • Authors: Amit Kumar Gupta;Himanshu Agrawal;Vivek Agarwal;
      Pages: 1765 - 1774
      Abstract: In this paper, a novel transformerless topology is proposed for three-phase grid-connected applications. The proposed topology has eight switches, and it combines the advantages of both dc-bypass and ac-bypass circuit configurations. The modulation strategy for the proposed topology is based on sinusoidal pulsewidth modulation followed by dedicated logic functions enabling control over the full range of modulation index. Logic functions are responsible for producing gate pulses for the eight switches, which are controlled in such a way that the variation in common-mode voltage (CMV) during inverter operation is low. Low variation in CMV throughout the operation results in reduced leakage current. The topology is capable of limiting the leakage current as per the German standard DIN VDE 0126-1-1. The output voltage of the proposed topology is unipolar, which results in low stress on the output filter inductors and low THD. There are two additional switches in the proposed topology compared to the conventional three-phase topology, but due to the special modulation strategy used, the drop in efficiency is insignificant. Theoretical analysis, simulation, and experimental results are presented to validate the concept of the proposed topology. Results show low variation in CMV and low THD in the output grid current.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Comprehensive Analysis of Single-Phase Full-Bridge Asymmetrical Flying
           Capacitor Inverters
    • Authors: Gabriel Avila Saccol;Julian Cezar Giacomini;Alessandro Luiz Batschauer;Cassiano Rech;
      Pages: 1775 - 1786
      Abstract: This paper presents a comprehensive analysis of single-phase full-bridge asymmetrical flying capacitor inverters under distinct capacitor voltage values. The asymmetrical operation is explored in order to increase the number of output levels for the same number of semiconductors. A formation law for the flying capacitors' voltages is proposed according to the desired number of output levels. The voltage regulation of the flying capacitors is carried out using the charge regulation analysis. The modulation strategy is also verified to overcome the inverter unbalance problem. Simulation and experimental results are included to demonstrate the performance of the proposed structures.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Acoustic Detection of Cracks and Delamination in Multilayer Ceramic
    • Authors: Saku Levikari;Tommi J. Kärkkäinen;Caroline Andersson;Juha Tammminen;Pertti Silventoinen;
      Pages: 1787 - 1794
      Abstract: Multilayer ceramic capacitors (MLCC) are the most widely used capacitor type in the electronics industry. However, the brittle ceramic dielectric makes MLCCs prone to mechanical damage. Manufacturing defects or damage during board assembly may cause a capacitor to prematurely fail during its operational life. Here, we demonstrate the fast and non-destructive acoustic screening of MLCCs. Soldered 2220-sized MLCCs were subjected to ac voltage frequency sweeps, causing them to vibrate mechanically. Acoustic responses of the capacitors were measured before and after subjecting the test circuit board to severe bending. The results show that the cracks and delaminations caused by bending induce characteristic changes in the capacitors' acoustic response. A support vector machine classifier was trained to successfully detect damaged capacitors based on their acoustic response.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Thermal Performance Evaluation of a 1.7-kV, 450-A SiC-MOSFET Based Modular
           Three-Phase Power Block With Wide Fundamental Frequency Operations
    • Authors: Sayan Acharya;Xu She;Maja Harfman Todorovic;Rajib Datta;Gary Mandrusiak;
      Pages: 1795 - 1806
      Abstract: To accelerate wide industry adoption of Silicon Carbide (SiC) based technology, a three-phase two-level inverter based power block is designed with the latest generation high performance 1.7 kV/450 A SiC-Mosfet module from General Electric. The designed power block is expected to replace the currently standardized 1.7 kV/450 A Silicon (Si) insulated gate bipolar transistor (IGBT) based three-phase power block. Power converters face thermal challenges when subjected to very low fundamental frequency operations (below 10 Hz). This is particularly relevant in the wind power applications. At low operating fundamental frequencies, the junction temperature of the power device experiences high peak-to-peak ripple, which degrades the reliability of the power modules significantly. This paper presents the thermal performance of the designed power block and draws comparisons with a similar rated Si-IGBT module based power blocks, especially at low output fundamental frequency operations. Key performance indices, including power rating curves at different switching frequencies and power factors; temperature ripple at different fundamental frequencies, are examined. Simulation and experimental results are provided to validate the claims. The results indicate that the SiC-Mosfet module based power block can be a promising replacement for the Si-IGBT based power block especially in applications where wide range of fundamental frequency operations are needed.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Robustness of 650-V Enhancement-Mode GaN HEMTs Under Various Short-Circuit
    • Authors: He Li;Xiao Li;Xiaodan Wang;Xintong Lyu;Haiwei Cai;Yazan M. Alsmadi;Liming Liu;Sandeep Bala;Jin Wang;
      Pages: 1807 - 1816
      Abstract: This paper presents the short-circuit behavior and degradation of 650-V/60-A enhancement-mode Gallium nitride (GaN) high electron mobility transistors (HEMTs) under various test conditions. First, this paper introduces the basic information of device, test method, and platform. Subsequently, single pulse, 10-μs short-circuit tests are performed from 50 to 400 V to extract the typical behavior of devices. Both short-circuit current self-regulation phenomenon and quick failure have been observed. Simultaneously, the short-circuit behavior of the device at various gate drive voltages and temperatures has been explored to identify the protection condition. Then, repetitive short-circuit tests have been performed to reveal device degradation trends. As a result, their output current reduction and gate-to-source threshold voltage shift have occurred. This paper shows the critical need to improve the robustness of this type of GaN HEMT from the device and circuit perspectives.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Supercapacitors Characterization and Modeling Using Combined
           Electro-Thermal Stress Approach Batteries
    • Authors: Kosseila Bellache;Mamadou Baïlo Camara;Brayima Dakyo;
      Pages: 1817 - 1827
      Abstract: This paper presents the supercapacitors (SC) behavior characterization using the temperature combined to the frequency of the dc-current ripples called here electro-thermal stress. To characterize the evolution of the resistance and the capacitance of the SC, the authors have evaluated the impact of the state of charge (SoC), the number of cycles, the temperature, and the temperature combined to the frequency of the dc-current ripples. This approach enables to show the variations of the SCs resistance and capacitance according to the real constraints imposed by application. The main contribution of this paper is focused on the SCs aging characterization and modeling, using the electro-thermal stress. The experimental tests of the SC characterization and modeling are based on the charge/discharge operations, using the fluctuating and no-fluctuating dc-current waveforms. The proposed model takes into account the variations of the resistance and capacitance of the SC according to the temperature, the frequency of dc-current ripples and the SoC. The terminal voltage of the SC obtained from the proposed model is close to the experimental result, with an error about 1%. So, the proposed model is satisfactory to predict the SCs behavior during the charge/discharge operations using a fluctuating dc-current combined to a variable temperature and SoC.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Bonding of Large Substrates by Silver Sintering and Characterization of
           the Interface Thermal Resistance
    • Authors: Shan Gao;Zhenwen Yang;Yansong Tan;Xin Li;Xu Chen;Zhan Sun;Guo-Quan Lu;
      Pages: 1828 - 1834
      Abstract: Low-temperature silver sintering technology, which has been proven to be a promising die-attach solution, was extended to bonding large substrates. Strong bonding strengths for substrates with a dimension of greater than 25 mm × 50 mm were achieved by sintering a nanosilver paste at temperatures below 270 °C under a pressure of less than 5 MPa. To characterize the thermal performance of the substrate-attach interface, we applied a transient thermal technique with cumulative structure function analysis. Using self-heating and the temperature-sensitive threshold voltage of a power device, we measured the transient thermal responses of the device placed at various locations on the bonded structures. Each transient thermal response was used to determine the cumulative structure function, which represents the relationship between cumulative thermal capacitance and cumulative thermal resistance from the device junction to the ambient environment. Two-dimensional maps corresponding to interface thermal resistance were obtained from structure function plots. We found that for well-bonded substrates, the average specific thermal resistance contributed by the sintered silver interface was between 5.20 and 5.78 mm2K/W with a variation of 4.7%-6.0%.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • An On-Board Model-Based Condition Monitoring for Lithium-Ion Batteries
    • Authors: Taesic Kim;Amit Adhikaree;Rajendra Pandey;Dae-Wook Kang;Myoungho Kim;Chang-Yeol Oh;Ju-Won Baek;
      Pages: 1835 - 1843
      Abstract: A model-based condition monitoring for lithium-ion (Li-ion) batteries involves estimating critical model parameters (e.g., capacity and impedance) and operational states [e.g., state of charge (SOC) and state of health]. This is important to design high-performance and safety-critical battery systems. Moreover, the tuning parameters of the condition monitoring algorithms significantly influence the performance of the algorithms. This paper proposes a real-time model-based condition monitoring for Li-ion batteries based on a real-time second-order resistor-capacitor electrical circuit battery model. The proposed method consists of an extended Kalman filter based online parameter identification and a smooth variable structure filter based state estimation. The two filters are systematically integrated to cooperate with each other and named hybrid filter (HF). Furthermore, a proposed particle swarm optimization based tuning parameter optimization is employed to find the optimal tuning parameters of the HF. The proposed method is compared with the dual extended Kalman filter (DEKF) via simulations and validated by experiments using a low-priced microcontroller. The results show that the proposed method can effectively choose the tuning parameters and has less computational complexity and higher accuracy of the SOC and capacity estimation than those of the conventional DEKF. Therefore, the proposed HF can be suitable for use in real-time embedded battery management system applications.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Wind Turbine Bearing Fault Diagnosis Based on Sparse Representation of
           Condition Monitoring Signals
    • Authors: Jun Wang;Wei Qiao;Liyan Qu;
      Pages: 1844 - 1852
      Abstract: An effective way to save the costs for data storage and transmission in bearing fault diagnosis of wind turbines is to use a sparse representation of massive condition monitoring signals. A proper dictionary that is adaptive to the analyzed signal containing time-varying components is a key issue to improve the sparse level in the sparse representation method, which has not been addressed in the literature. This paper explores a new sparse representation method that uses a new time-varying cosine-packet dictionary for the bearing fault diagnosis of wind turbines operating under varying speed conditions. First, the time-varying shaft rotating frequency (SRF) of a wind turbine is estimated from a generator current signal recorded synchronously with the vibration signal. Then, the new dictionary is designed, in which the basic functions, called time-varying cosine packet, change with the SRF. Finally, a sparse coefficient spectrum (SCS) of the vibration envelope signal is constructed by the sparse coefficients of the signal projection on the new dictionary. The merits of the proposed sparse representation method are that the dictionary designed is adaptive to the variations of major frequencies of the vibration signals, and the nonzero sparse coefficients over the dictionary designed have a clear physical meaning, i.e., representing the amplitude weights of the major order components contained in the vibration envelope signals. Therefore, the possible bearing fault characteristic orders can be identified from the SCS of the vibration envelope signal. Laboratory and field test results show that the sparse coefficients obtained by the new sparse representation method are suitable for the representations of the bearing vibration signals and the SCS is effective for bearing fault diagnosis of direct-drive wind turbines.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Control of Energy Storage System Integrating Electrochemical Batteries and
           Supercapacitors for Grid-Connected Applications
    • Authors: Joan Rocabert;Ruben Capó-Misut;Raúl Santiago Muñoz-Aguilar;José Ignacio Candela;Pedro Rodriguez;
      Pages: 1853 - 1862
      Abstract: The implementation of ancillary services in renewable energy based generation systems requires controlling bidirectional power flow. For such applications, integrated energy storage systems (ESSs) in such generation platforms have emerged as a promising solution. However, a large variety of ESS solutions are available in the market, and even hybrid systems are proposed to optimize the overall performance. In this regard, the integration of supercapacitors (SCs) and electrochemical batteries is an attractive and feasible solution, as it takes the most of the combination of the large storage capacity of batteries with the high dynamic performance of SCs. This combination enables the implementation of energy and power services, such as inertia emulation, black start, or power oscillation damping among others. This solution avoids oversizing ESS and enlarges the battery lifetime, since the SCs absorve the high dynamic response meanwhile the battery feeds an attenuated power profile. This paper presents a strategy to manage mixed energy storage technologies, composed by a direct connection of a battery and an SC bank interfaced through a dc-dc converter. A power control loop distributes the power flow through each element in order to achieve an optimized performance, meanwhile, it permits to provide grid-frequency support and minimizes the number of cycles applied to the battery. The analysis made and the initial sections are endorsed by simulation and experimental results collected in a 50-kW test-bench.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Control of Wind–Diesel Hybrid System With BESS for Optimal
    • Authors: Shailendra Kumar Tiwari;Bhim Singh;Puneet Kumar Goel;
      Pages: 1863 - 1872
      Abstract: This study presents a wind energy conversion system (WECS) with a diesel generator (DG). The proposed system with its control regulates the loading of DG to achieve a low-specific fuel consumption. The generator used in WECS is a doubly fed induction generator (DFIG). It consists of two voltage-source converters for the system control. The rotor-side converter helps in achieving the maximum power-point tracking of the wind turbine. The generator-side converter (GSC) helps in regulating the DG generation, while maintaining DFIG as well as DG currents balanced and harmonics within the requirement of the IEEE-519 standard for variety of loads. The system envisages an energy storage by connecting a battery bank at the dc bus of DFIG. The battery bank provides a buffer storage. The GSC also provides a path for the surplus or deficient power through the battery bank. The proposed system is modeled using Sim-power-system tool box of MATLAB and its performance results are presented for conditions such as synchronisation of the wind generator, variation of nonlinear and unbalanced loads, and varying wind speeds. Under all these scenarios, the currents flowing through both the generators are balanced. Finally, the effectiveness of the system is demonstrated experimentally on a prototype developed in the laboratory.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A HTF-Based Higher-Order Adaptive Control of Single-Stage Grid-Interfaced
           PV System
    • Authors: Vandana Jain;Ikhlaq Hussain;Bhim Singh;
      Pages: 1873 - 1881
      Abstract: In this paper, a hyperbolic tangent function (HTF) based higher order adaptive control algorithm is used with perturb & observe based maximum power point tracking algorithm for a three-phase, single-stage, grid-interfaced solar photovoltaic system with distribution static compensator capabilities. The variable learning based HTF control algorithm is used for the reduction of the mean square error and increases the tracking speed in the system, thereby improving the response of the system. The HTF-based control algorithm is simple in implementation with easy mathematical formulations. The proposed system is simulated in MATLAB/Simulink and is tested on a developed prototype in the laboratory under various abnormal conditions, such as variable solar irradiation, load unbalancing, and voltage sag/swell. The response of system is satisfactory and the total harmonic distortions of grid current are within the limit, as outlined in the IEEE-519 standard.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Numerical Simulation of Tracking Modes for Compound Parabolic Collector
           With Tubular Receiver
    • Authors: Sainath A. Waghmare;Kaustubh V. Chavan;Nitin P. Gulhane;
      Pages: 1882 - 1889
      Abstract: Correct placement of solar collectors is one of the important parameters for maximum utilization of heat radiated by the sun. Compound parabolic collector (CPC) with low acceptance angle needs frequent tracking to collect the maximum amount of solar radiation. The number of tracking depends on the location of CPC with respect to the sun position throughout a day. This study is executed to investigate the amount of solar incident flux falls on the reflector of the CPC by the implementation of five different tracking modes. The numerical analysis is performed on CPC geometry with the 50 number of possible orientations for five tracking modes and 10 h. These results are compared with theoretical results for validation purpose. It is observed that mode 3, mode 4, and mode 5 give more solar heat flux but offers more complexity in mounting and tracking as is compared to mode 1 and mode 2. Also, the shading effect of receiver tube on the heat flux distribution is presented which would reduce the optical efficiency.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Maximum Power Point Estimation for Photovoltaic Strings Subjected to
           Partial Shading Scenarios
    • Authors: Jieming Ma;Haochuan Jiang;Ziqiang Bi;Kaizhu Huang;Xingshuo Li;Huiqing Wen;
      Pages: 1890 - 1902
      Abstract: Partial shading is an unavoidable complication in the field of photovoltaic (PV) generation. Bypass diodes have become a standard feature of solar cell arrays to improve array performance under partial shading scenarios (PSS). However, the current-voltage and power-voltage characteristic data vary with different shading patterns. In this paper, a shading pattern detection algorithm is first proposed to estimate the number of shaded modules in a PV string. The result is then fed to a field-support vector regression (F-SVR) model, in which the measured features are transferred into a style-free high-dimension space prior to data training. The process of style-normalized transformation enables the features to be independent and identically distributed. Both simulations and experiments are conducted to evaluate the F-SVR model's ability to estimate the voltage at maximum power points. The results show that the proposed maximum power point estimation method can evidently reduce prediction errors.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Cascade Control With Adaptive Voltage Controller Applied to Photovoltaic
           Boost Converters
    • Authors: Lucas Vizzotto Bellinaso;Henrique Horst Figueira;Mauro Fernando Basquera;Rodrigo Padilha Vieira;Hilton Abílio Gründling;Leandro Michels;
      Pages: 1903 - 1912
      Abstract: DC-DC boost converters have been widely employed at the dc input of grid-tied photovoltaic (PV) inverters. In order to comply with grid standards, their control systems must usually work in two operation modes: Maximum power point tracking (MPPT) mode and limited power tracking (LPT) mode. MPPT algorithms reach high dynamic and static efficiencies when they operate with high-speed PV voltage control, because PV voltage is not significantly dependent on solar irradiance variations. On another hand, high-speed LPT mode can be obtained by controlling inductor current, which is proportional to the power injected into the dc bus. Both modes can be integrated in a cascade control scheme with an inner and fast current loop and an outer voltage loop. The main challenge is that both voltage and current small-signal models are highly dependent on the operation point of the PV array, temperature, and solar irradiance. This may cause control interactions between both loops and instability, especially when small film capacitors are used in parallel with the PV array. A common approach is to increase the input capacitance and design a low-speed PV voltage controller, which is not the best solution when high MPPT dynamic efficiency is necessary. To overcome these challenges, this paper proposes a cascade control structure based on an inner non-linear current controller and an outer adaptive voltage controller with fast detection of the PV array's model without requiring extra current sensor. A control design methodology and a MATLAB stability analysis tool are presented to support application engineers. The proposed control system has been experimentally validated using a PV array and a boost converter switched at 40 kHz. PV voltage settling time lower than 8 ms has been achieved for low and high solar irradiance, demonstrating the efficacy of the proposed technique.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • An Improved 0.8 VOC Model Based GMPPT Technique for Module Level
           Photovoltaic Power Optimizers
    • Authors: Mustafa Engin Başoğlu;
      Pages: 1913 - 1921
      Abstract: Photovoltaic modules may experience some mismatching conditions that affect their available power capacity, causing inefficient maximum power point tracking (MPPT). Furthermore, their power-voltage (P-V) characteristic curve becomes a multi-peak structure in such conditions owing to the presence of bypass diodes included since every part of the modules may receive different solar irradiance. By taking into account these facts, this paper introduces an improved global MPPT technique comprising 0.8 VOC model and the limited and adaptive scan approach. The proposed technique eliminates the requirement of some threshold value, leading to unreliable operation which the classical 0.8 VOC model based studies suffer from. Furthermore, the tracking time has been reduced substantially with the proposed technique by limiting scanning interval. Performance of the proposed technique has been verified by experimental studies and compared with classical 0.8 VOC model and a full scanning technique, which have been already presented in the literature. Experimental results show that the proposed technique is simple to be implemented and it has better performance than classical 0.8 VOC model, full scanning, and perturb and observe algorithms. Therefore, the proposed technique is feasible and it can be used technically in module level distributed MPPT (DMPPT) applications.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Compact Methodology Via a Recurrent Neural Network for Accurate
           Equivalent Circuit Type Modeling of Lithium-Ion Batteries
    • Authors: Ruxiu Zhao;Phillip J. Kollmeyer;Robert D. Lorenz;Thomas M. Jahns;
      Pages: 1922 - 1931
      Abstract: This work investigates the modeling of lithium-ion batteries (LIBs) with a recurrent neural network (RNN), rather than with an equivalent circuit or similar type model as is typically used. The RNN is trained with dynamic battery data, such as vehicle drive cycle test results. Specialized characterization tests and model parameterization are not necessary, simplifying the process of battery modeling. A compact unified methodology consisting of an RNN with gated recurrent unit and deep feature selection structures is utilized. A total of two RNNs are evaluated, one with current as the input and another with power as the input. Both RNN forms accurately model LIB dynamic responses including battery nonlinear behavior at different temperatures. The models are compact in size, require fewer characterization tests compared to conventional equivalent circuit models, and can be further used as an LIB simulator in model-based design and hardware-in-loop applications to test battery management systems and other electronic components.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Efficiency Degradation Model of Lithium-Ion Batteries for Electric
    • Authors: Eduardo Redondo-Iglesias;Pascal Venet;Serge Pelissier;
      Pages: 1932 - 1940
      Abstract: The purpose of this paper is to analyze efficiency degradation of lithium-ion batteries. Two lithium-ion cell technologies are considered under calendar ageing. It is well-known that ageing mechanisms have an impact in cells' performances. Most of studies focus on capacity fade and impedance rise but efficiency is less frequently studied. However, from the application point of view, battery efficiency degradation directly impacts the system energy efficiency. Results reveal the importance of considering battery ageing in the design phase of electric vehicles, not only for capacity but also for efficiency reasons: efficiency degradation depends of the technology, so when comparing two technologies one must take into account the cells' performances not just when cells are fresh but during the whole lifespan. Another finding reported in this paper is the high correlation between capacity fade and energy efficiency for the tested technologies. Finally, two empirical models for energy efficiency degradation were developed in both technologies: the first one is based on the Eyring relationships and the second one lies on the existing correlation between capacity fade and efficiency. Quality of each model is reported for both model types and battery technologies.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Dual-Channel Magnetically Integrated EV Chargers Based on
           Double-Stator-Winding Permanent-Magnet Synchronous Machines
    • Authors: Zheng Wang;Bochen Liu;Lei Guan;Yue Zhang;Ming Cheng;Bo Zhang;Liang Xu;
      Pages: 1941 - 1953
      Abstract: In this paper, a dual-channel isolated magnetically integrated charger is proposed for electric vehicles (EVs). The key is to apply and operate two interleaved power charging channels, each of which is composed of one dual-active-bridge isolated converter and one voltage-source inverter. The proposed configuration not only offers electric isolation under charging operation but also provides modular design and operation for each power conversion channel. By integrating the grid inductances with the double-stator-winding permanent-magnet (PM) synchronous machine under charging operation, the volume and weight of the charging system are saved for EVs. By reconfiguration of power circuits, the proposed dual-channel magnetically integrated EV chargers can be used for both single-phase and three-phase charging operations. The mechanical vibration caused by interaction between grid currents and PM flux can be mitigated by using the dual-channel charging operation. The interleaved operation and the phase-shifted modulation have been proposed for the dual charging channels to offer low current ripple on battery side and better harmonic performance on grid side. Furthermore, chaotic modulation strategies have been proposed to reduce the distinct switching harmonics in spectrum, which will facilitate improving the conducted electromagnetic compatibility in EVs. The experiments have been carried out on a 1-kW laboratory prototype to verify the validity of the proposed schemes.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • High-Speed Coreless Axial-Flux Permanent-Magnet Motor With Printed Circuit
           Board Winding
    • Authors: Neethu S;Saurabh Prakash Nikam;Sumeet Singh;Saumitra Pal;Ashok K. Wankhede;B. G. Fernandes;
      Pages: 1954 - 1962
      Abstract: Gearless and compact motors operating at high speeds (above 10 000 r/min) are increasingly being used in many fields. This paper presents the design and analysis of a coreless axial-flux permanent-magnet motor for high-speed, low-power applications. The proposed motor is designed to rotate at a speed of 30 000 r/min. To ensure the reliability of the motor at high speeds, it is essential to minimize torque ripple and the magnetic attraction between the stator and the rotor in the axial direction. Therefore, in this paper, a novel coreless stator design using multilayer printed circuit board (PCB) is proposed. The PCB stator ensures uniform distribution of the phase windings, which minimizes harmonics in the back EMF of the motor. The multilayer PCB stator makes the motor highly compact, efficient, and reliable. To improve the air-gap flux density in the coreless design, a lightweight Halbach-array based rotor is used and the Halbach magnets are covered with a high-strength nonmagnetic material to achieve high rotor integrity. MagNet 3-D and COMSOL Multiphysics are used for the finite element analysis and optimization of the motor and the simulation results are presented. A prototype of the motor is fabricated and tested with sensorless field oriented control to validate the simulation results. The back EMF obtained for the prototype is sinusoidal and its performance characteristics ensure efficient and reliable performance at high speeds.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • ZVS Soft Switching Operation Range Analysis of Three-Level Dual-Active
           Bridge DC–DC Converter Under Phase Shift Control Strategy
    • Authors: Li Jin;Bangyin Liu;Shanxu Duan;
      Pages: 1963 - 1972
      Abstract: The switches of three-level dual active bridge (3L-DAB) dc-dc converter under phase shift control may operate with hard working especially when the voltage conversion ratio is not equal to one, which will lead to high power loss and low system efficiency. A comprehensive analysis of the ZVS soft switching operation range of 3L-DAB is presented for the first time. The power characteristics of 3L-DAB operating under phase shift control is analyzed. Then, the ZVS operation range of the switches in the primary and secondary sides varied with phase shift ratios and voltage conversion ratio is deduced. The ZVS operation range is obtained by using steady-state time domain analysis under two conditions, without and with considering the junction capacitance of the semiconductor, and the comparative analysis are carried out later. Finally, simulation and experimental results obtained from a 3L-DAB prototype verify the discussed theoretical analysis.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • New Insights Into Model Predictive Control for Three-Phase Power
    • Authors: Yongchang Zhang;Jie Liu;Haitao Yang;Shengwen Fan;
      Pages: 1973 - 1982
      Abstract: Deadbeat control (DBC) has been investigated for decades because of its simple concept and satisfactory performance. Recently, finite control set-model predictive control (FCS-MPC) attracted wide attention in the control of power converters. Unlike DBC, FCS-MPC does not employ a modulator and directly manipulate switching states by minimizing a cost function. To improve the steady-state performance, some improved FCS-MPCs introducing two or three vectors during one control period were proposed in the existing literature. This paper proposes new insights into multiple-vector FCS-MPC for power converters by investigating its relationship with space vector modulation based DBC (SVM-DBC). Analytical studies show that two kinds of predictive methods can be unified in one framework when the control target is to minimize the tracking error. Different from enumeration-based vector selection in conventional FCS-MPC, the vector sequence and duration of the proposed multiple-vector FCS-MPC are directly reconstructed from SVM-DBC. Theoretical analysis on the state-of-the-art DBC and FCS-MPC, as well as experimental test on a three-phase two-level voltage source pulsewidth modulation rectifier confirms the effectiveness of the proposed method.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Cross-Regulated Closed-Loop Control for Hybrid L-Z Source Inverter
    • Authors: Avneet Kumar Chauhan;Sai Teja Mulpuru;Mayank Jain;Santosh Kumar Singh;
      Pages: 1983 - 1997
      Abstract: Recently, switched inductor-impedance source inverter (L-ZSI) based hybrid converter was reported as a potential candidate for the dual output (dc and ac) applications. This converter has two operating modes based on inductor current nature: 1) continuous current mode (CCM); and 2) discontinuous current mode (DCM). However, the converter performs well only during CCM. To get rid of problems present in hybrid L-ZSI, modified hybrid L-ZSI (MHLZSI) was reported. To demarcate the CCM and DCM, boundary condition was derived based on the average inductor current. However, the actual boundary condition is dependent on the combined effect of inductor current ripple and average inductor current. In this paper, theoretical analysis is presented by taking into account the effect of inductor current ripple. Furthermore, it is proved that MHLZSI is capable of achieving higher gain when operated in DCM. In addition, a closed-loop control for MHLZSI is designed. State space analysis is presented to derive the output to control transfer function for both dc and ac loads. Both the controllers are designed based on PI control to ensure cross regulation. Theoretical analysis is validated by experimental analysis.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Intelligent Adaptive Dynamic Surface Control System With Recurrent Wavelet
           Elman Neural Networks for DSP-Based Induction Motor Servo Drives
    • Authors: Fayez F. M. El-Sousy;Khaled Ali Abuhasel;
      Pages: 1998 - 2020
      Abstract: In this paper, an intelligent adaptive dynamic surface control system (IADSCS) with recurrent wavelet Elman neural network (RWENN) for induction motor (IM) servo drive is proposed. The IADSCS comprises a dynamic surface controller (DSC), a RWENN uncertainty observer, and a robust controller. First, a computed torque controller (CTC) is designed to stabilize the IM servo drive. Then, a nonlinear disturbance observer (NDO) is designed to estimate the nonlinear lumped parameter uncertainties (PU) existed in the CTC law. However, the IM servo drive performance is degraded by the NDO error due to the PU. To improve the robustness of the IM servo drive due to external load disturbances and PU, an IADSCS is designed to achieve this purpose. In the IADSCS, the DSC is used to overcome the explosion of the complexity in the backstepping design technique and the RWENN identifier is used to approximate the lumped PU and compounded disturbances. In addition, the robust controller is designed to recover the approximation error of the RWENN. The stability of the closed-loop system is guaranteed by the Lyapunov stability theory. All control algorithms are implemented using dSPACE1104 DSP-based control computer. The simulation and experimental results show the superiority of the proposed IADSCS in external load disturbance suppression and the robustness against PU.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Modified DC Chopper for Limiting the Fault Current and Controlling the
           DC-Link Voltage to Enhance Fault Ride-Through Capability of Doubly-Fed
           Induction-Generator-Based Wind Turbine
    • Authors: Seyed Behzad Naderi;Michael Negnevitsky;Kashem M. Muttaqi;
      Pages: 2021 - 2032
      Abstract: A simple conventional dc chopper is employed to protect the doubly-fed induction generator (DFIG) from overvoltage; however, it is not capable to keep the transient overcurrent in an acceptable level in stator and rotor sides. Therefore, an effective current-limiting strategy should be incorporated with the dc chopper to improve the fault ride-through capability of the DFIG. In this paper, a modified DC chopper is proposed not only to keep the dc-link voltage in an acceptable range, but also to limit the high-current level in the stator and the rotor sides in a permissible level without incorporating any extra fault-current-limiting strategy. Unlike the conventional dc chopper, in the proposed dc chopper, it is not required to stop rotor-side converter (RSC) switching and employ high-rated-current antiparallel diodes. The proposed modified dc chopper is placed between the dc-link capacitor and the RSC. In the proposed switching strategy of the modified dc chopper, three extra semiconductor switches are included, which are triggered to insert dc chopper resistance either in parallel or series connections with the dc link regarding the dc-link voltage level and the dc-link current level, respectively. Calculation of the dc chopper resistance is discussed. To prove the effectiveness and robustness of the proposed modified dc chopper in terms of both limiting the fault current and controlling the dc-link voltage of the DFIG, symmetrical and asymmetrical grid faults are applied in a power system including the DFIG-based wind turbine modeled in PSCAD/EMTDC so.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Model Predictive Observer Based Control for Single-Phase Asymmetrical
           T-Type AC/DC Power Converter
    • Authors: Shakil Ahamed Khan;Youguang Guo;Jianguo Zhu;
      Pages: 2033 - 2044
      Abstract: This paper presents a robust control strategy for the control of single-phase five-level asymmetrical T-type ac/dc power converter. A cascaded control scheme consisting of a finite control set model predictive control (FCS-MPC) with an extended state observer (ESO) is proposed to govern the converter. In this scheme, a proportional integral (PI) controller combined with an ESO-based disturbance observer is employed as an external control loop. This control loop dynamically modifies the active power reference to realize the desired operating point of the system state (converter output voltage). The proposed control system presents a high degree of disturbance rejection capability and robustness against the external disturbances to the converter, whereas the conventional PI control performance suffers in the presence of these disturbances. In this paper, the inner current tracking loop is accomplished by an FCS-MPC algorithm. This algorithm is derived to force the input currents to track the reference values while realizing a user-defined reactive power and maintaining balanced voltages in the series-connected capacitors. Theoretical analysis and the design procedure of the proposed control system are presented. Finally, experimental studies are conducted to verify the effectiveness of the proposed control scheme.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Renewable Energy Sources Integration and Control in Railway Microgrid
    • Authors: Soukaina Boudoudouh;Mohammed Maaroufi;
      Pages: 2045 - 2052
      Abstract: The traffic rail increase implies an increase in the electric energy consumption. Hybridizing the railway substations with hybrid energy sources based on renewable energy sources and storage units connected to a dc bus may be a solution to contribute to the partial independence of energy producers in the sector of traffic rail. A smart control is highly recommended in order to avoid disturbing the traffic or the energy quality of railway lines. This paper proposes a reversible, self-adaptive, autonomous, and intelligent distributed generator connected to the catenary thanks to the dc-bus distributed control by the multiagent system. The results analysis has shown that the proposed control architecture can be a solution to face the issues related to the traffic railway issues.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Hardware Testing of Sliding Mode Controller for Improved Performance of
           VSC-HVDC Based Offshore Wind Farm Under DC Fault
    • Authors: Mounir Benadja;Miloud Rezkallah;Seghir Benhalima;Abdelhamid Hamadi;Ambrish Chandra;
      Pages: 2053 - 2063
      Abstract: This paper proposes a sliding mode control (SMC) method for an onshore voltage source converter (VSC) used in a high-voltage-direct-current (HVDC) transmission system. The onshore VSC-HVDC station is based on a two-level voltage converter topology that is used to interconnect an offshore wind farm (OWF) with the ac main grid via two dc cables. The OWF is composed of ten variable speed wind turbines based on permanent magnet synchronous generators (VSWT/PMSGs). The VSWT/PMSGs are connected in parallel to a common dc bus. The ac main grid receives the required active power from the OWF through a transformer, 12-pulse diode rectifiers, boost converters, two dc cables, and a VSC-HVDC station. The boost converters are used to operate at speeds for maximum power extraction from the VSWT. SMC is used to ensure a stable operation of the VSC-HVDC station during dc fault, as well as to avoid controller saturation, a behavior that is usually seen when using linear controllers. The effectiveness of the proposed control method on system operation under dc fault is demonstrated by simulations carried out using matlab/Simulink. In addition, a scaled-down laboratory prototype of the system is built and tested to validate the performance of the proposed control scheme.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • An Investigation on Diagnosis-Based Power Switch Lifetime Extension
           Strategies for Three-Phase Inverters
    • Authors: Enes Ugur;Serkan Dusmez;Bilal Akin;
      Pages: 2064 - 2075
      Abstract: Fault diagnosis and failure prognosis of power electronics systems are essential for various mission critical applications, where safety, continuity, and survivability of the system are of paramount importance. With the recent advances in power device failure precursor identification and lifetime estimation, it is possible to extend the lifetime of the power devices, and thereby converters through secondary control schemes. The essence of the lifetime extension strategies relies on either reducing the power loss on the degraded device(s) and shifting it to other parts, or decreasing the total power loss of the converter. As the power converters are optimized for efficiency and total harmonic distortion (THD) requirements, these secondary control strategies can result in operations above the design limits. This paper proposes a hybrid secondary lifetime extension control scheme for three-phase inverters based on the identified failure precursors, which dynamically changes the modulation scheme and adjusts the switching frequency. In the content of this paper, the tradeoff between the THD and achievable lifetime extension is addressed, and a control algorithm is proposed, which maximizes the lifetime with feasible lowest THD.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Low-Complexity State-Space-Based System Identification and Controller
           Auto-Tuning Method for Multi-Phase DC–DC Converters
    • Authors: Marc Kanzian;Harald Gietler;Christoph Unterrieder;Matteo Agostinelli;Michael Lunglmayr;Mario Huemer;
      Pages: 2076 - 2087
      Abstract: The importance of online system identification (SI) in power electronics is ever increasing. It enables the tracking of system parameters, which in turn can be used for online controller tuning. Hence, SI is a key element for improving a converter's dynamic performance, stability, reliability. In this paper, a novel state-space-based SI approach utilizing the step-adaptive approximate least squares estimation algorithm with observation matrix randomization is proposed. The presented concept yields an accurate state-space model of the converter while simultaneously achieving a fast convergence rate and low computational complexity. Consequently, the estimated state-space model is utilized to automatically tune a full state feedback controller. This results in an improved converter performance in terms of overshoots, undershoots, and settling times. The proposed concept is verified by a prototype system comprising a two-phase buck converter and a field-programmable gate array. The provided measurement results highlight the effectiveness and benefits of the presented method over the state-of-the-art algorithms, as well as z-domain estimation. It is shown that the number of required estimation iterations is more than halved in comparison with the state-of-the-art parametric SI approaches, while accuracy is improved.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Modified Carrier-Based Advanced Modulation Technique for Improved
           Switching Performance of Magnetic-Linked Medium-Voltage Converters
    • Authors: Md. Ashib Rahman;Md. Rabiul Islam;Kashem M. Muttaqi;Youguang Guo;Jianguo Zhu;Danny Sutanto;Gang Lei;
      Pages: 2088 - 2098
      Abstract: The high-frequency magnetic link is gaining popularity due to its lightweight, small volume, and inherent voltage balancing capability. Those features can simplify the utilization of a multilevel converter (MLC) for the integration of renewable energy sources to the grid with compact size and exert economic feasibility. The modulation and control of the MLC are crucial issues, especially for grid-connected applications. To support the grid, the converter may need to operate in an overmodulation (OVM) region for short periods depending upon the loading conditions. This OVM operation of the converter causes increased harmonic losses and adverse effects on the overall system efficiency. On top of that, the size and cost of filtering circuitry become critical to eliminate the unwanted harmonics. In this regard, a modified OVM scheme with phase-disposed carriers for a grid-connected high-frequency magnetic-link-based cascaded H-bridge (CHB) MLC is proposed for the suppression of harmonics and the reduction of converter loss. Furthermore, with the proposed OVM technique, the voltage gain with the modulation index can be increased up to the range which is unlikely to be achieved using the classical ones. Extensive simulations are carried out with a 2.24 MVA permanent magnet synchronous generator based wind energy conversion system, which is connected to the 11 kV ac grid through a high-frequency magnetic-link and a five-level CHB MLC. A scaled down laboratory prototype is implemented to validate the performance of the converter.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Multifunctional Single-Phase Grid-Integrated Residential Solar PV
           Systems Based on LQR Control
    • Authors: Naima Arab;Bachir Kedjar;Alireza Javadi;Kamal Al-Haddad;
      Pages: 2099 - 2109
      Abstract: This paper presents a multifunctional single-stage residential photovoltaic power supply based on a linear quadratic regulator (LQR). The system makes use of a single-phase power converter connected to the grid through an LCL filter. A robust LQR with added integral action (LQRI) controller is designed to incorporate added functions such as a power line conditioner, an active power regulator, and a voltage stabilizer. The perturb-and-observe algorithm is used to generate the reference signal for the fluctuating dc bus voltage as well as to extract the maximum power from the solar panels. Full modeling of the converter in the D-Q reference frame is presented. An LQRI is designed to achieve the optimal multifunctionality operation of the residential power supply. Simulation and experimental results confirm the expected performance of the proposed controller for insolation and load variations.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • A Robust Power Management Strategy With Multi-Mode Control Features for an
           Integrated PV and Energy Storage System to Take the Advantage of ToU
           Electricity Pricing
    • Authors: Viet Thang Tran;Kashem M. Muttaqi;Danny Sutanto;
      Pages: 2110 - 2120
      Abstract: In this paper, a power management strategy (PMS) for an integrated residential solar photovoltaic (PV) and energy storage unit (ESU) is proposed for both grid-connected and islanded operations to take the advantage of time-of-use pricing. This is an effective solution to integrate storage and renewable energy sources, such as solar PV, with the conventional grid to improve the reliability and efficiency of the power system and to reduce the total electricity cost for the consumer. An automatic switching control strategy is proposed to realize a smooth switching among the various operation modes of the proposed energy management strategy. The integrated PV-storage system is composed of a 5-kW PV array, a 3.5-kW·h ESU formed by 12-V single lead acid batteries, and three power converters. The PMS ensures seamless switching of the ESU converter between the charging and the discharging mode and seamless switching between the inverting and the rectifying mode of the grid converter. It also ensures that the local loads are supplied when the grid fails. An experimental setup has been implemented in the laboratory using the real-time field-programmable gate array general-purpose inverter control card from National Instrument to verify the practical feasibility of the proposed PMS under the various scenarios of the PV irradiation, load changings, and the state of charge of the ESU. The results show that the proposed PMS is effective and robust against various scenarios.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Application of Next-Generation Motor Management Relays Improves System
           Reliability in Process Industries
    • Authors: David B. Durocher;Matthew R. Hussey;David E. Belzner;Luigi Rizzi;
      Pages: 2121 - 2129
      Abstract: This paper describes advances in functionality of motor management relays in terms of both motor protection and predictive diagnostics. Network connectivity of these devices via high-speed Ethernet/IP allows real-time monitoring of system parameters, providing analytics to allow process industry users to better manage system processes to improve reliability, efficiency, and safety. A case study of a recent application of new motor management relays is included in this paper, offering producers a specific example of how new motor management relays are applied and outlining details involved to leverage the latest technologies.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Analysis of Asymmetrical Component Influence on Arc Current in the
           Determination of Arc Thermal Performance Value of Protective Personal
    • Authors: Marcio Bottaro;Thais Ohara de Carvalho;Luis Eduardo Caires;Hélio Eiji Sueta;Paulo Futoshi Obase;Hédio Tatizawa;Ivan Bueno Raposo;
      Pages: 2130 - 2137
      Abstract: An evaluation of relevance of current asymmetry on arc flash tests intended to determine arc rating parameters on fabrics and garments, as well as face shields, gloves, and other materials were performed. Asymmetrical current is mentioned in American Standards (ASTM F 1959) to be maximum during tests and a reference on International Standard IEC 61482-1-1:2009, item 6.9, where an X/R ratio is required to obtain an asymmetry factor of 2.3, with a recommended source voltage of 2000 V. IEEE 1584 studies on the other hand states all calculation processes not clearly regarding asymmetry of fault current but assuming the linear effect of time and current on energy derived from steady-state current values. Technical basement for the asymmetry factor is never mentioned on arc flash test standards but it is supposed to be related to test strength conditions. As thermal conversion relationship with asymmetry is not clear in the literature, this study investigated, simulated, and performed practical measurements of electrical and thermal parameters related to arc flash tests, concluding that both symmetrical and asymmetrical arcing currents will confer the same arc rating results. Practical tests also showed that a source voltage of 2000 V is necessary only to produce arcing current asymmetry as lower voltages can be used to ignite and keep symmetrical arcing current for sufficient time on the arc rating tests, as previously regarded on literature which reduces significantly test setup and circuitry.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Current-Limiting Arc Flash Quenching System for Improved Incident Energy
    • Authors: Robert J. Burns;Adams D. Baker;Dan E. Hrncir;
      Pages: 2138 - 2143
      Abstract: In response to a growing concern to mitigate arc flash incident energy hazards, the latest edition of the National Electric Code NFPA70-2017 includes requirements for reducing clearing time of overcurrent protective devices with a continuous current rating of 1200 A or higher. Section 240.87 lists seven options for reducing arc fault energy. This paper focuses on Method 4: energy-reducing active arc flash mitigation systems.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Modeling and Evaluation of Paper Machine Coater Sections Part 1: 1-Coater
           Section and Tension Setpoints
    • Authors: Guillermo Ramírez A.;M. Anibal Valenzuela;Steve Pittman;Robert D. Lorenz;
      Pages: 2144 - 2154
      Abstract: Coater sections are challenging to tune during the commissioning of a paper machine. This paper presents a detailed mechanical-electrical model of a 1-coater section, which includes a linear, operating point model of the sheet in the different spans, all the drivetrain components, and the vector-controlled ac drives. The sheet model considers tail widening as well as the effect of coating and drying on the sheet elastic constant, activation of the torque current control, and the beginning of coating. The developed model allows for complete evaluation of the different transient events including paper slack due to load impacts. Results show that the best performance of the drives is obtained operating the spans with even sheet tensions, which reduces and/or eliminates the operation of the drives in regeneration or braking zones.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Modeling and Evaluation of Paper Machine Coater Sections Part 2: 2-Coater
           Section and Control Loops’ Bandwidths
    • Authors: Guillermo Ramirez A.;M. Anibal Valenzuela;Steve D. Pittman;Robert D. Lorenz;
      Pages: 2155 - 2164
      Abstract: Coater sections are examples of multi-span web transporting systems, with dynamic characteristics related to the sheet properties and control schemes. This paper first describes and analyzes a set of field records of a production 2-coater section paper machine. Then, extending the 1-coater section model developed in a related paper, a precise simulation model of a 2-coater section is implemented. This model is used to evaluate the beginning of the coating process and the effect on the section responses of different bandwidth settings in the tension and speed controllers. Results show agreement with the field records and demonstrate that the developed model is a powerful tool to analyze and understand the behavior of coater sections during both transient and steady-state conditions.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • TRV (Transient Recovery Voltage) in High Voltage Current Interruption
    • Authors: J. C. Das;
      Pages: 2165 - 2172
      Abstract: This paper provides concepts of transient recovery voltage (TRV) in ac high-voltage interruption. The ANSI/IEEE and IEC standards differ in the TRV profiles. This paper describes the TRV profiles according to these standards and compares these with practical calculations. Working examples of calculations in practical systems are included. ANSI/IEEE standards have now adopted IEC methodology.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
  • Transformer Fuse Sizing—The NEC is not the Last Word
    • Authors: Del John Ventruella;
      Pages: 2173 - 2180
      Abstract: It is widely accepted that transformer primary side fuses should be appropriately sized to protect load side transformers. Proper sizing involves consideration of fault and overload conditions. The basis for such sizing is commonly derived from National Electrical Code (NEC) limits. The NEC imposed limits are the legal limits, but direct application of the NEC maximum values to size transformer primary side fuses is ill advised. The primary side fuse for medium voltage (MV) applications greater than 1000 V, as with most MV protective devices, is not intended to provide overload protection for the transformer, that is achieved by design (considering the intended loading on the transformer). The NEC recognizes this by permitting the fuse to be sized up to 300% of the transformer full-load ampere rating. It is clearly not a good idea to apply the maximum limits of the NEC as an absolute standard for fuse sizing to protect transformers in the absence of the application of other techniques (such as plotting the ANSI/IEEE thermal-mechanical damage characteristic for transformers on a time current curve along with the primary side (MV) fuse time current curve characteristic). These considerations are discussed in the course of this paper. The focus here is on dry type, low voltage transformers, although the content can be easily extended to liquid-filled transformers by using the equations from the appropriate standard.
      PubDate: March-April 2019
      Issue No: Vol. 55, No. 2 (2019)
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
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