for Journals by Title or ISSN
for Articles by Keywords
help

 A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  

       | Last   [Sort by number of followers]   [Restore default list]

  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: 315)
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: 269)
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: 191)
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: 168)
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  

       | Last   [Sort by number of followers]   [Restore default list]

Similar Journals
Journal Cover
IEEE Transactions on Power Electronics
Journal Prestige (SJR): 2.215
Citation Impact (citeScore): 9
Number of Followers: 71  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0885-8993
Published by IEEE Homepage  [191 journals]
  • IEEE Power Electronics Society
    • Abstract: Provides a listing of current staff, committee members and society officers.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • IEEE Power Electronics Society
    • Abstract: Provides a listing of current committee members and society officers.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Administrative committee
    • Abstract: Provides a listing of current committee members and society officers.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • A Fixed-Length Transfer Delay Based Adaptive Frequency-Locked Loop for
           Single-Phase Systems
    • Authors: Zhiyong Dai;Zhen Zhang;Yongheng Yang;Frede Blaabjerg;Yigeng Huangfu;Juxiang Zhang;
      Pages: 4000 - 4004
      Abstract: This letter presents an adaptive frequency-locked loop (FLL) with fixed-length transfer delay units for single-phase systems. By analyzing the relationship between the grid voltage and its transfer delay signals, a linear regression model of the grid voltage is established. Accordingly, a transfer delay based adaptive FLL (TD-AFLL) is proposed. A mathematic proof indicates that the proposed TD-AFLL can reject both phase offset errors and double-frequency oscillatory errors. Thus, the grid voltage parameters can be estimated accurately, even when the frequency drifts away from its nominal value. Moreover, fast dynamics of the TD-AFLL are achieved due to the transfer delay structure. Experiments verify the effectiveness of the proposed method.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • A Rotation-Free Wireless Power Transfer System With Stable Output Power
           and Efficiency for Autonomous Underwater Vehicles
    • Authors: Zhengchao Yan;Baowei Song;Yiming Zhang;Kehan Zhang;Zhaoyong Mao;Yuli Hu;
      Pages: 4005 - 4008
      Abstract: This letter proposes a rotation-free wireless power transfer system based on a new coil structure to achieve stable output power and efficiency against rotational misalignments for charging autonomous underwater vehicles. The new coil structure has two decoupled receivers composed of two reversely wound receiver coils and the magnetic flux directions of the two receivers are perpendicular to each other, guaranteeing a relatively constant total mutual inductance and a decoupled characteristic under rotational misalignments. The proposed coil structure is verified via finite element analysis based on ANSYS Maxwell. A rotation-free LCC–LCC compensated WPT prototype is built and the experimental results verify the theoretical analysis and simulations. The system can deliver 664 W with a dc–dc efficiency of 92.26% under the best case and 485 W with a 92.10% dc–dc efficiency under the worst case.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Compact Switched Capacitor Multilevel Inverter (CSCMLI) With Self-Voltage
           Balancing and Boosting Ability
    • Authors: Jagabar Sathik Mohamed Ali;Vijayakumar Krishnasamy;
      Pages: 4009 - 4013
      Abstract: This letter presents a compact switched capacitor multilevel inverter (CSCMLI) topology with reduced switch count and with self-voltage balancing and boosting ability. The operational mode of the proposed CSCMLI is discussed. A comparative analysis in terms of number of switches and blocking voltages is presented against recent switched capacitor multilevel inverter topologies. Further to enhance the quality of the output voltage, a new level shifted multicarrier pulsewidth modulation (PWM) technique is recommended. This modulation technique produces low THD and high rms voltage. The proposed modulation technique is implemented in the nine-level CSCMLI with single dc source and two capacitors. The simulated and experimental results are verified for a switching frequency of 50 Hz and 2.5 kHz using the proposed PWM control.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • A Novel Nine-Level Quadruple Boost Inverter With Inductive-Load Ability
    • Authors: Junfeng Liu;Weijie Lin;Jialei Wu;Jun Zeng;
      Pages: 4014 - 4018
      Abstract: A novel single-phase nine-level switched-capacitor inverter (9LSCI) is presented with quadruple boost ability and reduced components. The proposed topology with single dc source employs only eight switches to realize nine-level output, self-voltage balance of capacitors, quadruple boost and inductive-load ability, thus, the effective cost is cut down compared to other switched-capacitor multilevel inverters (SCMLIs). Different from other SCMLIs, the proposed 9LSCI has no need for back-end H-bridge, of which four switches need to withstand the peak voltage of output. Hence, total standing voltage can be reduced. The operation principles containing the self-voltage balance of capacitors are described in detail. The quantitative comparisons, modified cost function, as well as the loss evaluations are examined in depth. Finally, multicarrier phase disposition pulsewidth modulation method is adopted and a laboratory prototype is implemented with the rated output of 220 V–500 W. The experimental results also verify the feasibility of the proposed topology.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Dual-Channel Push–Pull Isolated Resonant Gate Driver for High-Frequency
           ZVS Full-Bridge Converters
    • Authors: Qunfang Wu;Qin Wang;Jinyi Zhu;Xiao Lan;
      Pages: 4019 - 4024
      Abstract: In this letter, a new zero-current-switching (ZCS) dual-channel push–pull isolated resonant gate driver (DPIRGD) is proposed to drive a pair of power mosfet in one bridge leg operating at high-switching frequency. The characteristics of the proposed DPIRGD include capability to provide two isolated complementary drive signals, low-gate drive loss, and high reliability of the turn-off status. Compared to the previous gate driver suitable for the zero-voltage-switching full-bridge converters, the proposed DPIRGD achieves similar gate drive loss but implements low components enabling to reduce the drive cost and increase the reliability. The operation principle, loss analysis, optimum design, and comparison study of the DPIRGD are presented in detail. The experimental results are shown to verify the effectiveness of the proposed concept. This solution has achieved nearly 70.7% reduction in gate drive power loss compared to the conventional voltage-source drive circuit.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • A Model Predictive Current Controlled Bidirectional Three-Level DC/DC
           Converter for Hybrid Energy Storage System in DC Microgrids
    • Authors: Xinan Zhang;Benfei Wang;Ujjal Manandhar;Hoay Beng Gooi;Gilbert Foo;
      Pages: 4025 - 4030
      Abstract: This letter proposes a new three-level dc/dc converter configuration for a hybrid energy storage system (HESS) in dc microgrids. It effectively integrates different energy storage devices (ESDs), such as battery and ultracapacitor (UC), using one converter with bidirectional power flow. Furthermore, the proposed converter provides the flexibility of independent regulation of different ESDs with significantly reduced inductor current ripple due to the availability of three voltage levels. The voltage ratings of power semiconductors employed in this converter are also reduced. To further enhance the performance of HESS, a constant switching frequency based model predictive current control is employed for HESS regulation. The design guideline and operating principle of the proposed converter are discussed. Experimental results are presented to verify the efficacy of the proposed converter and control.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • A Five-Switch Bridge Based Reconfigurable LLC Converter for Deeply
           Depleted PEV Charging Applications
    • Authors: Cheng Li;Haoyu Wang;Ming Shang;
      Pages: 4031 - 4035
      Abstract: This letter presents a reconfigurable dual LLC converter based on a five-switch bridge to charge the deeply depleted plug-in electric vehicle onboard battery packs. Due to the reconfiguration of the primary-side switch network, two resonant tanks could operate in integrated half-bridge, half-bridge, hybrid-bridge, and full-bridge modes. Thus, four operation modes are derived, with their normalized voltage gains scaled to 1:2:3:4, respectively. Those four modes enable a squeezed switching frequency span, which is close to the resonant frequency. Therefore, the efficiency performance over an ultra-wide output voltage range can be optimized. Zero-voltage-switching can be realized in all power mosfets over the entire load range. The operating principles, voltage gains analysis are briefed. A 1.1-kW-rated prototype converting the 390-V input to 100–420 V output, is designed and tested to validate the proof of concept. A total of 97.64% of peak efficiency and good efficiency over the full charging range is reported.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Small-Signal Model of Switched Inductor Boost Converter
    • Authors: Jia Yao;Kaisheng Zheng;A. Abramovitz;
      Pages: 4036 - 4040
      Abstract: Equivalence between the switched inductor boost (SIB) converter and the tapped inductor boost (TIB) converter is suggested and the required conditions are derived. Based on the equivalence conditions, it is further shown that dynamic model of the SIB converter is merely a private case of the more general TIB converter. The model is derived using the tapped inductor switcher switched flow graph modeling approach. Simulation and experimental results are also reported.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Optimality in the Sense of Arm Current Distribution of MMC VSC-HVDC
    • Authors: Pablo Briff;
      Pages: 4041 - 4047
      Abstract: This letter investigates the optimality of the modular multilevel converter (MMC) voltage source converters high-voltage direct current (VSC-HVDC), which constitutes a linear time-invariant (LTI) system for sufficiently large number of submodules per valve. The contribution of this letter is the mathematical proof that MMC VSC-HVDC is the optimal LTI topology in the sense of arm current distribution. Namely, the findings of this work show that MMC VSC-HVDC attains an optimal limit in the way the ac and dc components of the converter arm currents are distributed in the field of linear converter topologies, and may only be outperformed by nonlinear or time-varying VSC-HVDC topologies.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • A Modular Multilevel Converter With Ripple-Power Decoupling Channels for
           Three-Phase MV Adjustable-Speed Drives
    • Authors: Mohamed S. Diab;Ahmed M. Massoud;Shehab Ahmed;Barry W. Williams;
      Pages: 4048 - 4063
      Abstract: This paper presents a drive system based on a modular multilevel converter (MMC) with high-frequency magnetic channels between adjacent-arm submodules (SMs), suitable for medium-voltage, high-power three-phase variable-speed machines. The configuration employs chains of dual half-bridge (DHB) modules linking adjacent SMs of three-phase symmetrical arms. The DHB modules are operating as power channels enabling energy exchange to restore the power imbalance among the SM capacitors. This allows arms’ ripple-powers to be entirely decoupled through bidirectional power transfer between adjacent-arm SMs, resulting in a near ripple-free SM capacitor voltage profile. Therefore, the MMC common problem of wide voltage fluctuation across SM capacitors is comprehensively solved, independent of the operating frequency. Additionally, a significant reduction in the sizing requirement of SM capacitance is achieved. The configuration is able to drive multimegawatt machines from standstill to the rated speed at the rated torque operating condition. The operating principle of the proposed MMC configuration is explained and necessary mathematical analysis is derived. Features and viability of the proposed drive system are verified through simulation and experimentation.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Lifetime Estimation of DC-Link Capacitors in Adjustable Speed Drives Under
           Grid Voltage Unbalances
    • Authors: Haoran Wang;Pooya Davari;Huai Wang;Dinesh Kumar;Firuz Zare;Frede Blaabjerg;
      Pages: 4064 - 4078
      Abstract: Electrolytic capacitor with a dc-side inductor is a typical dc-link filtering configuration in grid-connected diode rectified adjustable speed drives (ASDs). The criteria to size the dc-link filter are mainly from the aspects of stability and power quality. Nevertheless, the reliability of the dc-link filter is also an essential performance factor to be considered, which depends on both the component inherent capability and the operational conditions (e.g., electrothermal stresses) in the field operation. Nowadays, unbalanced voltage has the most frequent occurrence in many distribution networks. It brings more electrical-thermal stress to the component, affecting the reliability of the capacitors. In order to study the reliability performance of the LC filter in an ASD system quantitatively, this paper proposes a mission profile based reliability evaluation method for capacitors. Different from the conventional lifetime estimation, a nonlinear accumulated damage model is proposed for the long-term estimation, considering the nonlinear process of equivalent series resistor growth and capacitance reduction during the degradation. Based on the proposed lifetime estimation procedure, four case studies are investigated: first, lifetime benchmarking of capacitors in LC filtering and slim capacitor filtering configurations; second, scalability analysis for the lifetime of capacitors in terms of system power rating and grid-unbalanced levels; third, lifetime estimation of capacitors in the dc-link filter with long-term mission profile; and fourth, the impact of the capacitor sizing on the lifetime of the dc-link capacitor under grid-balanced and grid-unbalanced conditions. The results serve as a guideline for proper selection of dc-link configurations and parameters to fulfill a specification in ASDs.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • An Air-Gap Shape Optimization for Fringing Field Eddy Current Loss
           Reductions in Power Magnetics
    • Authors: Denys Igorovych Zaikin;Stig Jonasen;Simon Lee Mikkelsen;
      Pages: 4079 - 4086
      Abstract: This study reduced winding eddy current losses by optimizing the shapes of air gaps in inductors. Finite element method software was used for inductor simulations. A special script was made to implement an optimization algorithm to reach a minimum of an objective function. The objective function consisted of two weighted parts. The first part was the total losses of an inductor, and the second was the average flux density of a central leg's core around a gap. A relationship between these parts was used to determine how deeply the inductor could be saturated to minimize the total loss of the inductor. Simulation results and experimental data were noted, and the total loss and temperature reductions of the inductor were demonstrated.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Analysis and Design of a High Power Density Flying-Capacitor Multilevel
           Boost Converter for High Step-Up Conversion
    • Authors: Zitao Liao;Yutian Lei;Robert C. N. Pilawa-Podgurski;
      Pages: 4087 - 4099
      Abstract: This paper explores the use of the flying-capacitor multilevel (FCML) topology in high step-up conversion. Compared to the conventional two-level boost converter, the FCML topology utilizes high energy density capacitors to facilitate inductors with storing and transferring energy during the conversion process, which brings features, such as lower voltage stress on the switches, reduced voltage stress on the inductor, and high effective switching frequency at the switching node. As a result, the total volume of the passive components in the converter is greatly reduced while maintaining high efficiency at high voltage gain. To demonstrate the potential high power density and high efficiency, a hardware prototype that converts 100 V to 1 kV with 820-W maximum output power is built. Such specifications require careful optimizations in many aspects of the converter to ensure a high power density and efficiency design. The implemented solutions and associate design process are presented in detail, with comparison with other state-of-the-art solutions. The hardware prototype has successfully demonstrated a peak efficiency of 94.1%, and 329 W/in$^3$ (20 W/cm$^3$) overall power density.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • DC–DC Boost Converter With a Wide Input Range and High Voltage Gain
           for Fuel Cell Vehicles
    • Authors: Yun Zhang;Heyu Liu;Jing Li;Mark Sumner;Changliang Xia;
      Pages: 4100 - 4111
      Abstract: In fuel cell vehicles, the output voltage of the fuel cell source is typically much lower than the voltage required by the dc bus, and also this output voltage drops significantly as the output current increases. In order to match the output voltage of the fuel cell source to the dc bus voltage, a new dc–dc boost converter with a wide input range and high voltage gain is proposed to act as the required power interface, which reduces voltage stress across the power devices and operates with an acceptable conversion efficiency. A prototype rated at 300 W/400 V has been developed and the maximum efficiency of the proposed converter was measured as 95.01% at 300 W. Experimental results are presented to validate the effectiveness of the proposed converter.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Analysis and Design of Multiphase Receiver With Reduction of Output
           Fluctuation for EV Dynamic Wireless Charging System
    • Authors: Shumei Cui;Zhiyuan Wang;Shouliang Han;Chunbo Zhu;
      Pages: 4112 - 4124
      Abstract: The multiphase receiver for more steady output is proposed in this paper. The conventional power supply rail with multipole such as I-type, S-type, and n-type for dynamic wireless charging (DWC) system has a main drawback: the induced voltage of the double-D coil of receiver has a sinusoidal fluctuation along the driving direction and the fluctuation factor is 1.0. Therefore, the multiphase receivers including two-phase, three-phase, and four-phase receiver are proposed to solve the problem. The fluctuation factor, effective value (rms) of induced voltage and mutual inductance, cost, and loss of different numbers of phase in different connection modes are analyzed and compared. The applicable conditions of different types are given. The structure size of single-phase coil is optimized to achieve larger coupling coefficient. The influence of distance between phases on fluctuation factor and induced voltage (rms) are calculated and the design principle of the distance between phases is determined. Based on above research, design guideline for the multiphase receiver is proposed including the constraints of installation environment and the distribution of different phases. The structure size of single-phase coil and the distance between phases are optimized to improve the coupling coefficient and reduce cost, loss, and voltage level of resonator. Considering the practical application environment, a four-phase receiver of 10-kW DWC system is designed. A prototype system is also established and the analysis and simulation are verified. In the dynamic 10-kW experiment, the fluctuation factor is reduced to 0.146 from 0.3 of two-phase receiver and 1.0 of single-phase receiver.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Large Step Ratio Input-Series–Output-Parallel Chain-Link
           DC–DC Converter
    • Authors: Xiaotian Zhang;Mofan Tian;Xin Xiang;Javier Pereda;Timothy C. Green;Xu Yang;
      Pages: 4125 - 4136
      Abstract: High-voltage and high-power dc–dc conversion is key to dc transmission, distribution, and generation, which requires compact and efficient dc transformers with large step ratios. This paper introduces a dc–dc converter with the input-series–output-parallel arrangement of multiple high step ratio subconverter units. Each subconverter unit is an isolated modular dc–dc converter with a stack of half-bridge cells chopping the dc down to low voltage level. The transformer provides galvanic isolation and additional step ratio. The converter achieves a large step ratio due to the combination of the series-parallel configuration, the modular cells, and the isolation transformer. The proposed dc–dc converter is analyzed in a 30 kV–1 kV, 1-MW application to discuss the operation performance, tradeoffs, power efficiency, and selection of components. Finally, the converter is validated through a laboratory downscaled prototype.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • An Overview of Modular Multilevel Converters in HVDC Transmission Systems
           With STATCOM Operation During Pole-to-Pole DC Short Circuits
    • Authors: Thanh Hai Nguyen;Khalifa Al Hosani;Mohamed Shawky El Moursi;Frede Blaabjerg;
      Pages: 4137 - 4160
      Abstract: Fault-current handling capability of the modular multilevel converters (MMCs) under dc-cable short-circuit conditions is a major concern for the MMC applications on the high-voltage direct-current (HVDC) transmission systems, where the MMCs based on half-bridge submodules (SMs) cannot block the fault currents to protect the converter devices. In this paper, a comprehensive review for the fault-ride-through capability of the HVDC transmission systems based on the MMCs adopting different SM schemes is presented, where the MMCs can block the fault currents and compensate the reactive currents to the electric grid during the dc faults. An analysis of the dc short-circuit faults in the MMC is introduced and then the operation principle of different SM circuits building the MMC for blocking the fault currents is highlighted. The fault-tolerant operation of these MMC schemes as static synchronous compensator to enhance the ac grid stability during the dc faults is also investigated. A comparison in terms of investment cost, loss, volume, and controllability for various MMC topologies is performed. Comprehensive simulation results for the most promising topologies of the MMC with a capability of fault-ride through under dc-fault conditions are finally presented.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • A Method for the Calculation of the AC-Side Admittance of a Modular
           Multilevel Converter
    • Authors: Luca Bessegato;Lennart Harnefors;Kalle Ilves;Staffan Norrga;
      Pages: 4161 - 4172
      Abstract: Connecting a modular multilevel converter to an ac grid may cause stability issues, which can be assessed by analyzing the converter ac-side admittance in relation to the grid impedance. This paper presents a method for calculating the ac-side admittance of modular multilevel converters, analyzing the main frequency components of the converter variables individually. Starting from a time-averaged model of the converter, the proposed method performs a linearization in the frequency domain, which overcomes the inherent nonlinearities of the converter's internal dynamics and the phase-locked loop used in the control. The ac-side admittance obtained analytically is first validated by simulations against a nonlinear time-averaged model of the modular multilevel converter. The tradeoff posed by complexity of the method and the accuracy of the result is discussed, and the magnitude of the individual frequency components is shown. Finally, experiments on a down-scaled prototype are performed to validate this study and the simplification on which it is based.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Implementing an Impedance Compression Network to Compensate for
           Misalignments in a Wireless Power Transfer System
    • Authors: Jungwon Choi;Jiale Xu;Rawad Makhoul;Juan M. Rivas Davila;
      Pages: 4173 - 4184
      Abstract: This paper presents an impedance compression network (ICN) design in a wireless power transfer (WPT) system to compensate for distance or alignment variations between coils. In midrange WPT applications, magnetic resonant coupling coils are mainly implemented to achieve high efficiency for charging batteries. However, a distance or horizontal alignment variation between coils changes their coupling coefficient, and it decreases the overall performance of WPT systems because the zero voltage switching in a resonant inverter is lost. In order to reduce coil impedance variation, we propose an ICN that compresses variations in coil impedance. The ICN consists of a resistance compression network and a phase compression network to suppress magnitude and phase variations, respectively, in the coil impedance. Only passive components, such as inductors and capacitors, are used to implement an ICN.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Comparison of the Heat Transfer Capabilities of Conventional Single- and
           Two-Phase Cooling Systems for an Electric Vehicle IGBT Power Module
    • Authors: Itxaso Aranzabal;Iñigo Martínez de Alegría;Nicola Delmonte;Paolo Cova;Iñigo Kortabarria;
      Pages: 4185 - 4194
      Abstract: This paper presents a comparison of conventional single-phase water/glycol liquid and innovative two-phase cooling technology for thermal management of high-power electronics automotive insulated-gate bipolar transistor modules during a full drive cycle. The proposed two-phase cooling system is built using conventional automotive air conditioning components (a condenser, an expansion valve, a compressor, and vapor and liquid lines) and a conventional cold plate as used for single-phase cooling; thus, the design does not require the development of new technology for its implementation. Three-dimensional numerical simulation in COMSOL and experimental results of two-phase cooling have been obtained on a prototype and compared to conventional water/glycol cooling high-power electronics modules, with a considerable improvement on working temperature, power transfer capacity, and equalization of die temperatures during a full driving cycle. These results suggest that two-phase cooling using the same cold plates as in single-phase cooling can be used to substantially improve the performance and reliability of electric vehicle power converters without major changes.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • A Structurally Reconfigurable Resonant Dual-Active-Bridge Converter and
           Modulation Method to Achieve Full-Range Soft-Switching and Enhanced
           Light-Load Efficiency
    • Authors: Yiu Pang Chan;K. H. Loo;Muhammad Yaqoob;Y. M. Lai;
      Pages: 4195 - 4207
      Abstract: This paper proposes a reconfigurable dual-active-bridge (DAB) converter that is capable of switching between two converter structures for enhancing its performances at different output power levels. For 50%–100% load, the converter operates in full-bridge mode and achieves soft-switching in all switches independently of the input-to-output voltage ratio. Below 50% load, the converter is reconfigured to operate in half-bridge mode for reduced circulating current and improved light-load efficiency while maintaining the desired soft-switching characteristic of full-bridge mode. The achievement of soft-switching is aided by the use of a tuned $LCL$ resonant tank, which enables an accurate prediction of the phases of tank currents with respect to tank voltages, and therefore simplifies the realization of soft-switching. The effects of dead time are discussed and expressions for guiding the selection of appropriate dead time for ensuring soft-switching in practical implementation are derived. The proposed converter and the modulation scheme are experimentally verified with a 1.6-kW converter prototype, which demonstrates their merits in comparison with a nonreconfigurable, full-bridge DAB topology and conventional modulation schemes.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Dual-Voltage-Rectifier-Based Single-Phase AC–DC Converters With Dual DC
           Bus and Voltage-Sigma Architecture for Variable DC Output Applications
    • Authors: Hongfei Wu;Meng Han;Kai Sun;
      Pages: 4208 - 4222
      Abstract: Novel single-phase ac–dc converters based on dual-voltage-rectifier (DV-rectifier) and voltage-sigma architecture is proposed in this paper. Dual dc-buses, i.e., a constant dc voltage bus and an adjustable dc voltage bus, are provided by the DV-rectifier. Voltages of the two dc-buses are stacked together on the output port through down-stream dc–dc transformers (DCXs). The dc output voltage is controlled by regulating the voltage of the adjustable dc-bus of the DV-rectifier. Therefore, voltage regulation is not required for the DCXs, which can always operate at their optimized operation point to ensure high efficiency. Since the voltage of the adjustable dc-bus is lower than the constant dc-bus, multi voltage-level characteristics can be obtained with the DV-rectifier, which is benefit for reduction of switching losses and improvement of conversion efficiency. In order to achieve current regulation of ac input port and voltage regulation of the two dc-buses simultaneously, multimode operation, and smooth mode transition strategies are proposed for the DV-rectifier. Operation principles, control strategies, and characteristics of the DV-rectifier and DCX-based ac–dc converter are analyzed in detail. Feasibility and effectiveness of the proposed solutions are verified with experimental results.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Design and Implementation of High Efficiency Control Scheme of Dual Active
           Bridge Based 10 kV/1 MW Solid State Transformer for PV Application
    • Authors: Tao Liu;Xu Yang;Wenjie Chen;Yang Li;Yang Xuan;Lang Huang;Xiang Hao;
      Pages: 4223 - 4238
      Abstract: One promising topology for solid state transformer (SST) is a modular multilevel cascaded converter, in which submodule is composed of dual active bridge (DAB) and H-bridge. For SST application in PV system, the efficiency could be severely affected especially for DAB due to the wide voltage and power range of PV panels. Thus, the motivation of this paper is to deal with the control strategy to improve DAB efficiency inside SST for PV application. Instead of utilizing time-domain based analysis method, which requires complex modeling process, this paper models DAB under frequency domain by fully considering the effect of both fundamental and harmonic frequency component. To achieve high efficiency operation, a multiorder reactive-current suppression (MRS) strategy is proposed by controlling phase shift angle as well as the duty cycles of primary and secondary side H-bridges. In terms of DAB controller design inside SST, the small signal model under MRS is established and a notch filter is implemented to suppress the second order line frequency fluctuation in the control loop. Finally, a 10 kV/1 MW SST prototype is introduced along with the system control structure and implementation method. The experiment of the submodule and SST confirms the effectiveness of proposed method.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Frozen Leg Operation of a Three-Phase Dual Active Bridge Converter
    • Authors: Saeid Haghbin;Frede Blaabjerg;Amir Sajjad Bahman;
      Pages: 4239 - 4248
      Abstract: Three-phase dual active bridge (DAB) topology is a potential alternative for high-power applications when a compact and efficient converter with a bidirectional power transfer capability is desired. In a constructed prototype, high-power SiC modules with dedicated drivers are utilized to achieve high-efficiency and compact size. Each module has two interconnected switches with anti-parallel diodes resembling a converter leg. It is observed that the driver halts the module operation as a result of protective actions such as overcurrent, gate undervoltage, or gate overvoltage. In this frozen leg mode, the module operates as a leg with two diodes until an external hardware signal resets the driver. The converter continues operation but with a reduced performance. Analysis, simulation, and verification of a three-phase DAB converter under a frozen leg operation are considered in this paper. The converter with a frozen leg has two different behaviors at light loads and heavy loads. Consequently, two different analysis methods are developed to solve converter operation in different load conditions. Results show that the power transfer capability is reduced, but this fault mode is nondestructive.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Common-Mode Current Suppression of Transformerless Nested Five-Level
           Converter With Zero Common-Mode Vectors
    • Authors: Wuhua Li;Yuxiang Wang;Jiawei Hu;Huan Yang;Chushan Li;Xiangning He;
      Pages: 4249 - 4258
      Abstract: Three-phase transformerless multilevel converters are widely used in the high-voltage photovoltaic power generation systems because of their low total harmonic distortion, high power density, and high conversion efficiency. One three-level flying capacitor converter and dual T-type three-level circuits can be combined to derive the compact and cost-effective nested five-level converter. However, due to the lack of an isolation transformer, the common-mode current is generated to degrade the converter performance. First, the common-mode equivalent circuit model of the nested five-level converter is initially derived to further explore its common-mode current generation mechanism. Then, the zero common-mode space vector modulation (ZCM-SVM) is proposed to reduce the common-mode current, which chooses the specific zero common-mode voltage space vectors to synthesize the reference vector. Then, an advanced coordinate transformation is introduced to realize the flexible sector selection and reduce the complexity of the vector action time calculation. The proposed modulation achieves the common-mode current suppression with high dc bus voltage utilization. Finally, the effectiveness of the proposed ZCM-SVM strategy is verified by simulation and experimental results.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • HVDC Circuit Breakers Combining Mechanical Switches and a Multilevel PWM
           Converter: Verification by Downscaled Models
    • Authors: Atsushi Suzuki;Hirofumi Akagi;
      Pages: 4259 - 4269
      Abstract: This paper presents two high-voltage direct-current circuit breakers that have the capability of interrupting a short-circuit current within several milliseconds. They consist of a current-limit inductor, a current-control inductor, one or two mechanical switches, and a multilevel converter with phase-shifted-carrier pulsewidth modulation. The two breakers can commutate an almost zero current from the main branch to the auxiliary branch. This paper proposes an original breaker with low-voltage and high-voltage mechanical switches connected in series, followed by a simplified breaker with a single high-voltage mechanical switch. Finally, this paper includes experimental verification by two slightly different downscaled breakers rated at 300 Vdc and 150 Adc, as well as confirmation of an actual original breaker by circuit simulation using the “PSCAD/EMTDC” software package.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Investigating the EMI Mitigation in Power Inverters Using Delay
           Compensation
    • Authors: Michele Perotti;Franco Fiori;
      Pages: 4270 - 4278
      Abstract: Electromagnetic emissions (EMEs) of electric and electronic units should comply with national and international standards. Software approaches to reduce the conducted EME are preferable, since they do not require additional on-board hardware. Many techniques have been developed with different levels of efficiency. This paper aims to analyze a new software approach to mitigate the conducted emissions of three-phase power inverters, focusing on those used to drive brushless DC motors. This has been done reducing the conducted electromagnetic interferences common mode (CM) component through software compensation of parasitic delays. The technique is verified both analytically and experimentally, and its performances have been compared to the spread spectrum modulation (SSM) ones. The proposed approach shows better performances with respect to SSM below 24 MHz. The results confirm the effectiveness of the delay compensation technique in terms of CM conducted emissions reduction. Moreover, the proposed approach has no drawbacks on safety and it does not present reductions in the inverter efficiency.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Optimization Method of CM Inductor Volume Taking Into Account the Magnetic
           Core Saturation Issues
    • Authors: Bilel Zaidi;Arnaud Videt;Nadir Idir;
      Pages: 4279 - 4291
      Abstract: Electromagnetic interference filters are broadly used in power electronic systems in order to respect electromagnetic compatibility normative constraints, which considerably increase overall cost and volume mainly because of the common-mode (CM) inductor. In this paper, a new method to calculate the optimal volume of the CM inductor is proposed. It takes into account core saturation issues that may greatly impact inductor volume and filter performances. Consequently, it is shown that in some cases, increasing the inductance value up to the best value can significantly reduce the filter volume in addition to further enhancing the filter attenuation. It is also shown that different nearly-best inductor geometrical parameters with different shape factors can be obtained, which provides an important degree of freedom to designers while introducing the filter in the energy conversion system.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Hybrid UP-PWM Scheme for HERIC Inverter to Improve Power Quality and
           Efficiency
    • Authors: Zhongting Tang;Mei Su;Yao Sun;Bin Cheng;Yongheng Yang;Frede Blaabjerg;Lina Wang;
      Pages: 4292 - 4303
      Abstract: The highly efficient and reliable inverter concept (HERIC) inverter is a cost-effective topology, which has low leakage currents and a relatively high efficiency. Thus, it is very suitable for transformerless photovoltaic systems. However, with the reported modulation methods, it is difficult to simultaneously maintain the high efficiency, good power quality, and reactive power injection of the HERIC inverter. In this paper, a hybrid unipolar pulsewidth modulation (UP-PWM) scheme is thus proposed to achieve those performances. The hybrid scheme adopts the conventional UP-PWM in the case of generating the positive power. When generating the negative power, a modulation scheme, which only requires the operation of freewheeling switches, is specifically proposed. Additionally, in the region of the output voltage and current zero-crossing points, a UP-PWM with modified deadtime is introduced. In order to validate the effectiveness of the proposed scheme, simulations and experiments are performed on a 4-kW HERIC inverter system with a 20-kHz switching frequency. The results demonstrate that the proposed hybrid UP-PWM method achieves a better performance in terms of reactive power injection than the conventional UP-PWM scheme, and a higher efficiency than the UP-PWM with deadtime. In addition, the proposed UP-PWM scheme also enables a better power quality.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Transformerless Bidirectional PWM Converter Integrating Voltage
           Multiplier-Based Cell Voltage Equalizer for Series-Connected Electric
           Double-Layer Capacitors
    • Authors: Kazuki Yashiro;Masatoshi Uno;
      Pages: 4304 - 4315
      Abstract: In the traditional energy storage systems consisting of series-connected energy storage cells such as electric double-layer capacitors (EDLCs), not only a bidirectional pulsewidth modulation (PWM) converter but also a cell voltage equalizer is required. The system is prone to complexity as two converters (i.e., the bidirectional converter and cell voltage equalizer) are separately necessary. This paper proposes the transformerless bidirectional PWM converter integrating the voltage multiplier-based cell voltage equalizer. An inductor in a conventional bidirectional PWM converter is replaced with series-connected inductors in the proposed converter in order to generate square-wave voltage with an arbitrary amplitude, by which the voltage multiplier is driven. The charge–discharge cycling test for nine EDLCs connected in series was performed using the proposed integrated converter from a voltage-imbalanced condition. The voltage imbalance was gradually eliminated during charge–discharge cycling, demonstrating the integrated functions.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • High-Efficiency Bidirectional Buck–Boost Converter for Photovoltaic and
           Energy Storage Systems in a Smart Grid
    • Authors: Hyeon-Seok Lee;Jae-Jung Yun;
      Pages: 4316 - 4328
      Abstract: This paper proposes a new bidirectional buck–boost converter, which is a key component in a photovoltaic and energy storage system (ESS). Conventional bidirectional buck–boost converters for ESSs operate in discontinuous conduction mode (DCM) to achieve zero-voltage switching turn-on for switches. However, operation in DCM causes high ripples in the output voltage and current, as well as low power-conversion efficiency. To improve the performance of the conventional converter, the proposed converter has a new combined structure of a cascaded buck–boost converter and an auxiliary capacitor. The combined structure of the proposed converter reduces the output current ripple by providing a current path and the efficiency is increased. A prototype was built and tested to verify the effectiveness of the converter. The proposed converter has a maximum efficiency of 98%, less than ${text{5.14}}{ text{V}}_{{text{p.p}}}$ of output voltage ripple, and less than ${text{7.12}}{ text{A}}_{{text{p.p}}}$ of output current ripple. These results were obtained at an input voltage of 160 V, switching frequency of 45 kHz, output voltage of 80–320 V, and output power of 16–160 W. The experimental results show that the proposed converter has improved performance compared to the conventional converter.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Accurate State of Charge Estimation With Model Mismatch for Li-Ion
           Batteries: A Joint Moving Horizon Estimation Approach
    • Authors: Jia-Ni Shen;Jia-Jin Shen;Yi-Jun He;Zi-Feng Ma;
      Pages: 4329 - 4342
      Abstract: The accurate state of charge (SOC) estimation plays a significant role in charge/discharge control, balance control, and safe management of lithium-ion batteries (LIBs). However, due to the model mismatch issues, either from battery inconsistency or battery dynamic characteristics difference, the accuracy of the model-based SOC estimation method is usually unsatisfactory. To solve this problem, a joint moving horizon estimation (joint-MHE) approach that can simultaneously estimate the model parameter and state is proposed here. In this paper, the circuit-equivalent battery model is first constructed by parameterizing the circuit parameters as polynomial function of SOC. Then, by the sensitivity analysis, the update parameters are selected and added to the state-space model as additional states. Finally, the joint-MHE strategy is conducted for the simultaneous parameter and SOC estimation. To investigate the performance of the proposed method thoroughly, three model mismatch conditions are considered, including battery inconsistency, battery dynamic characteristics difference, and the combination of both. The results demonstrate that the joint-MHE approach is an effective way to solve the model mismatch problem. Moreover, compared to joint extended Kalman filtering, the proposed approach can offer a more reliable, robust, and accurate SOC estimation of LIBs under various model mismatch conditions.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Transformerless Z-Source Four-Leg PV Inverter With Leakage Current
           Reduction
    • Authors: Xiaoqiang Guo;Yong Yang;Ran He;Baocheng Wang;Frede Blaabjerg;
      Pages: 4343 - 4352
      Abstract: Due to the lack of electrical isolation, the leakage current is one of the most important issues for transformerless photovoltaic (PV) systems. In this paper, a new modulation strategy is proposed to reduce the leakage current for a Z-source four-leg transformerless PV inverter. First, the common-mode loop model is presented. And then the common mode voltage behavior and the effect of factors on the leakage current are discussed. A new modulation strategy is proposed to achieve the step-up function and constant common mode voltage. Therefore, the leakage current can be suppressed effectively. Finally, the proposed strategy is digitally implemented and tested on the TMS320F28335 DSP and XC3S400 FPGA controlled hardware platform. The experimental results verify the effectiveness of the proposed solution.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Fully Integrated Low-Power Energy Harvesting System With Simplified Ripple
           Correlation Control for System-on-a-Chip Applications
    • Authors: Minseob Shim;Junwon Jeong;Junyoung Maeng;Inho Park;Chulwoo Kim;
      Pages: 4353 - 4361
      Abstract: This paper presents a fully integrated energy harvesting (EH) system that even includes an input capacitor and a simplified ripple correlation control (RCC) maximum power point tracking (MPPT) method for low-power system-on-a-chip applications. The proposed system implements the RCC block with a charge pump (CP) that can be integrated into the chip, instead of the inductive switching converter that is commonly used for conventional RCC methods. The CP changes the input impedance by changing the size of the flying capacitor to ensure system reliability. The simplified RCC method is implemented using a low-power analog divider operated in a subthreshold region. A test chip fabricated in a 180 nm CMOS process achieves over 95% MPPT accuracy with a very small input capacitor of 5 nF and a low quiescent current of 2.6 μA. The chip size of the entire system is 8 mm2, and the harvested power range is from 6 μW to 1.4 mW.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Principle and Robust Impedance-Based Design of Grid-tied Inverter with
           LLCL-Filter under Wide Variation of Grid-Reactance
    • Authors: Zhiheng Zhang;Weimin Wu;Zhikang Shuai;Xiongfei Wang;An Luo;Henry Shu-Hung Chung;Frede Blaabjerg;
      Pages: 4362 - 4374
      Abstract: Currently, how the inductive grid impedance variation affects the stability of digitally controlled grid-tied inverters with a high-order (LCL or LLCL) filter has been numerously studied. Note that a distributed power system may contain the capacitive load, the power factor correction (PFC) capacitor, and the long cable. During the design of grid-tied inverters, we should address the effects of the equivalent grid reactance, including both the inductive and the capacitive impedances, on the stability of system. Nevertheless, up to now, to the best knowledge of authors, the detailed parameter design method of the LCL- or LLCL-filter-based grid-tied inverter has not yet been introduced, when the capacitive grid impedance is addressed. In this paper, by using the passivity-based analysis, the detailed stability study on the LLCL-filter-based grid-tied inverter is carried out, when the grid reactance varies in a wide range. Based on the analysis, an exact and robust parameter design of system is proposed. Simulations and experimental results on a 220 V/2 kW prototype confirm that by using the proposed parameter design method, a high-performance grid-tied inverter system can be achieved under the rigid grid condition.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • High Step-Up Resonant DC/DC Converter With Balanced Capacitor Voltage for
           Distributed Generation Systems
    • Authors: Sungho Son;Oscar Andrés Montes;Adrià Junyent-Ferré;Minsung Kim;
      Pages: 4375 - 4387
      Abstract: We propose a high step-up resonant dc–dc converter that can achieve voltage balance of the resonant capacitors in distributed generation systems. By incorporating a switching mechanism on the secondary side, we achieve high step-up voltage gain with a minimum number of devices and without reverse-recovery problem. An active-clamp circuit installed on the primary side suppresses the surge voltage that occurs at switch components, recycles the energy stored in the leakage inductance, and provides an alternate resonant-current path formed by the leakage inductance and the output resonant capacitors. A dual resonance that occurs at the secondary side of the converter is exploited to reduce the turn-off current and switching loss significantly, and to achieve high power conversion efficiency. The resonant capacitor voltages remain in balance because the duty cycle of the primary-side switches is always set to 0.5, regardless of the input voltages and load variations. Design and analysis of the proposed converter are presented, and tests using a 400-W experimental prototype verify its superior performance.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Isolated Bidirectional DC–DC Converter With Quasi-Resonant Zero-Voltage
           Switching for Battery Charge Equalization
    • Authors: Junlong Lu;Yi Wang;Xin Li;
      Pages: 4388 - 4406
      Abstract: Charge equalization for a series-connected battery string is necessary to enhance usage life and performance of cells. In this paper, an isolated bidirectional dc–dc converter with quasi-resonant zero-voltage switching (ZVS) is proposed for centralized charge equalization system. Through the quasi-resonant operation, the proposed converter can achieve ZVS operations in both boost and buck modes, which decreases switching losses and improves the efficiency. The energy in leakage inductance is released to output side in the boost mode and recycled to the input side in the buck mode, which eliminates the voltage spike. Moreover, the proposed converter has fewer components than existing converters used in the centralized charge equalization system. The operating principle and theoretical derivation of the proposed converter are presented. The ZVS implementations and conditions are analyzed and illustrated in detail. Finally, the experiments using a 7.2 Ah battery string of 13 cells are conducted. The results verify the validity of the proposed converter and show that the equalizer achieves good performance in terms of equalizing speed and efficiency.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Family of Multiport Switched-Capacitor Multilevel Inverters for
           High-Frequency AC Power Distribution
    • Authors: S. Raghu Raman;Yat Chi Fong;Yuanmao Ye;Ka Wai Eric Cheng;
      Pages: 4407 - 4422
      Abstract: This paper proposes a family of multiport switched-capacitor multilevel inverter (SCMLI) topologies for high-frequency ac power distribution. It employs asymmetric dc voltage sources with a common ground that makes it ideal to be employed in renewable energy farms and modern electric vehicles. The proposed family of step-up SCMLI attains higher number of output voltage steps with optimum component count in comparison to several existing topologies. The problem of capacitor voltage balancing is solved as the capacitors are inherently charged to a finite voltage every half cycle. In-depth study on two staircase modulation strategies, namely, selective harmonic elimination and minimum total harmonic distortion (THD) scheme is presented with study on the variation of switching angles and THD with modulation indices under both schemes. Working principle and analysis are presented for the proposed family of topologies. Simulation outcomes are validated with experimental results under both the aforementioned modulation schemes with equal and unequal output voltage waveform steps.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Interleaved Active Clamp Forward Converter With Extended Operating Duty
           Ratio by Adopting Additional Series-Connected Secondary Windings for Wide
           Input and High Current Output Applications
    • Authors: Han-Shin Youn;Jae-Il Baek;Jae-Kuk Kim;
      Pages: 4423 - 4433
      Abstract: This paper presents a new interleaved active clamp forward converter for low and wide input, and high current output applications. In the proposed converter, the operating duty ratio can be extended over 0.5 due to the additional powering path resulting from additional series-connected secondary windings from each transformer. As a result, the proposed converter can be designed with large transformer turns ratio. Thus, since the proposed converter can reduce not only the primary RMS current but also switch turn-off current, it can achieve high efficiency. Moreover, since all secondary switches can operate without floating gate drivers, the proposed converter can maintain simple structure and low complexity of gate driving circuits in the secondary side. The validity of this proposed converter is verified by the experimental results from 36V–72 V input and 12 V/500 W output for the dc/dc prototype.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • A Self-Tuned Class-E Power Oscillator
    • Authors: Mohammad Mahdi Ahmadi;Maryam Salehi-Sirzar;
      Pages: 4434 - 4449
      Abstract: The efficiency and output power of a high-$Q$ Class-E power amplifier (PA) are very sensitive to the values of the circuit components. Any mismatch between the nominal Class-E frequency and the input clock frequency could result in considerable degradation in the efficiency and much change in the output power. In this paper, we present a new self-oscillating Class-E PA, or so-called Class-E power oscillator (PO), whose feedback network is mainly constructed of a low-$Q$ RC circuit. As a result, the phase response of the feedback network is almost flat around the operating frequency, and if the nominal Class-E frequency of the load network changes due to variations in the component values, the phase shift in the feedback network does not change considerably, and therefore, the Class-E operation of the circuit is substantially maintained. We also present a complete design procedure for the proposed Class-E PO. We have built and tested a sample Class-E PO based on the proposed circuit. At $V_{DD}= {text{4.5}},{text{V}}$, the measured oscillation frequency, output power, and efficiency of the circuit are 800 kHz, 0.96 W, and 89%, respectively. Simulation and measurement results confirmed that the efficiency and output power of the proposed Class-E PO have small sensitivities to the variations in the component values; therefore, we call the proposed circuit a self-tuned Class-E PO.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • SiC Stacked-Capacitor Converters for Pulse Applications
    • Authors: Xiaoyong Ren;Zhi-Wei Xu;Ke Xu;Zhiliang Zhang;Qianhong Chen;
      Pages: 4450 - 4464
      Abstract: Pulse power converters demands single high voltage and current pulse shape waveform in high temperature, heavy neutrons, and ions radiation environment, where ${text{50}}% sim {text{75}}%$ voltage derating margin is typically required for the power devices. silicon carbide (SiC) mosfets are promising to improve radiation reliability owing to wide band-gap. However, the conventional converters with off-the-shelf commercial SiC mosfets cannot provide enough voltage margin accordingly. A stack-capacitor pulse converter topology is proposed to reduce the voltage stress of switching devices and capacitors and improve the voltage derating capability significantly. The main idea is to build high voltage with multiple low voltage stacks instead of single high voltage capacitors, so that SiC mosfets can be applied with improved voltage margin. The method is to charge the stack-capacitors in parallel with fast charging speed, and discharge in series for high pulse voltage. The converter operates at higher switching frequency, which reduces the weight and size of the magnetic components. A 300-kHz prototype with 18–28 V input and 1  kV/ 100 A output was built using 650 V SiC devices, demonstrating 75% reduction of the voltage stress of the capacitors and power devices compared with the conventional converters.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Multi-Winding Configuration Optimization of Multi-Output Planar
           Transformers in GaN Active Forward Converters for Satellite Applications
    • Authors: Zhiliang Zhang;Binghui He;Dong-Dong Hu;Xiaoyong Ren;Qianhong Chen;
      Pages: 4465 - 4479
      Abstract: It is a serious challenge to find the optimal winding configuration that realizes minimum leakage inductance of multi-output multi-winding planar transformers due to the complex coupling relationship. The proposed idea is to build the mathematical model of leakage magnetic field energy and screen out all possible winding configurations to solve the minimum value with MATLAB programming. Then, only limited potential winding configurations need to be three-dimensionally simulated in Maxwell. By analyzing the inductance matrix, the leakage inductance of multi-winding planar transformers is solved. A full gallium nitride (GaN) active clamp forward converter with self-driven synchronous rectifiers (SRs) is presented with complete mode analysis. It is noted that the proposed active clamp technology uses the auxiliary winding with the nonfloating GaN switch compared to the conventional high-side clamping circuit, which is important for the satellite applications. The GaN drive chips for high reliable gate voltage are combined with self-driving. Considering the leakage inductance in each winding and junction capacitance of the GaN high electron mobility transistors, the oscillation frequency and amplitude over the switches are modeled quantitatively, which is important to minimize powertrain loop at MHz. The explanation of the root cause of the voltage spike in the converter is also presented. A prototype with 1 MHz, 100 V input, 5 V/6 A and ±12 V/0.83 A outputs was built to verify the proposed techniques.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • A New Grid-Connected DC/AC Inverter With Soft Switching and Low Current
           Ripple
    • Authors: Rahil Samani;Dawood Shekari Beyragh;Majid Pahlevani;
      Pages: 4480 - 4496
      Abstract: This paper presents a new dc/ac inverter for low-power applications (i.e., high-voltage, low-current applications), which offers soft switching of the power semiconductors and low output current ripple. In the proposed power circuitry, a novel ripple steering approach is used that can provide soft switching for the power semiconductors and significantly attenuate the high-frequency current ripple of the inverter. The proposed ripple steering technique utilizes the switching frequency and the duty cycle in order to perform the aforementioned tasks. Basically, the ripple steering technique steers the energy of the ripple to the output capacitances of the power semiconductors in order to provide the soft-switching condition. Theoretical analysis, simulation results, and experimental results verify the feasibility of the proposed technique and demonstrate the superior performance of the proposed inverter.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • An Interleaved Flyback-Typed LED Driver With ZVS and Energy Recovery of
           Leakage Inductance
    • Authors: Hung-Liang Cheng;Yong-Nong Chang;Hau-Chen Yen;Chih-Chiang Hua;Pei-Shuo Su;
      Pages: 4497 - 4508
      Abstract: Flyback converter has advantages of simple circuit configuration and easy control. However, it suffers two problems. One is the active switch is hard switching. The other is a very high voltage spike when the active switch is turned off. In order to solve these problems, this paper presents a novel dc-to-dc converter that mainly consists of two interleaved flyback converters. Both active switches can achieve zero-voltage switching on without the use of any active clamp circuit or snubber circuit. In addition, the leakage flux energy can be delivered to the output by using two added diodes. It helps to reduce the voltage spikes on the active switches and improve circuit efficiency. The steady-state analyses at different operation modes and the mathematical equations for parameters design are provided. Finally, a 200-W prototype circuit for driving high-brightness light-emitting diodes (LEDs) is built and tested to verify the feasibility of the proposed circuit. The LEDs are dimmed from 100% to 10% full power. Satisfactory performances are obtained from the experimental results.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • A Novel D-CLT Multiresonant DC–DC Converter With Reduced Voltage
           Stresses for Wide Frequency Variation Applications
    • Authors: Yi-feng Wang;Fuqiang Han;Liang Yang;Chengshan Wang;Bo Chen;Rong Xu;
      Pages: 4509 - 4523
      Abstract: In this paper, a dual-capacitor-inductor-transformer (CLT) (D-CLT) soft-switching dc–dc converter has been proposed. Combining the multiresonant technology, the converter employs two high-frequency transformers in the resonant tank and exhibits desirable characteristics. The fundamental and the third-order harmonics can be utilized to transfer active power simultaneously. The share of third harmonic is larger than first component. Thus, the converter can use the 100-kHz controlling signals to mainly transfer the 300-kHz active power, which makes it easier to realize high power density. Moreover, the available range for the third power delivery is expanded as well. A resonant zero point is introduced into the voltage gain curves. It ensures broadened voltage gain range (from zero to the maximum) and good protection for overcurrent issue. Then, improved soft-switching performances have been achieved: All the switches achieve the zero-voltage-switching (ZVS) turn-on, whereas all the diodes obtain the zero-current-switching (ZCS) turn-on and quasi-ZCS turn-off. Switching losses are constrained to the minimum. To verify the feasibility of the proposed converter, a 330-W prototype is established and tested. The results demonstrate the experiments match well with the theoretical analyses. The peak efficiency has reached 95.2%, although a high-loss diode bridge is adopted.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Robust Model Predictive Control With Simplified Repetitive Control for
           Electrical Machine Drives
    • Authors: Ying Liu;Shanmei Cheng;Bowen Ning;Yesong Li;
      Pages: 4524 - 4535
      Abstract: Conventional model predictive control (MPC) for electrical drives relies on the accuracy of system model, thus, its performance will deteriorate due to disturbances such as parameter mismatch and current distortion. To improve the robustness of MPC, a compensated scheme with simplified repetitive control (SRC) is proposed in this paper. Since the prediction of MPC is corrected with the assistance of compensation, a much more reasonable output is provided to promote system performance. An open-loop structure of repetitive control (RC) with two resonant units is applied for the proposed SRC to guarantee stability and maintain high accuracy for tracking disturbances, and moreover, SRC responds fast and just needs half of the data memory used by an ideal RC. Additionally, an output filter is designed to correct the quantizing error of frequency, thus, the frequency adaption is enhanced. To validate the feasibility and the effectiveness of the proposed method, a compensated MPC for permanent-magnet synchronous machine drive system is utilized. Both simulation and experiment results prove significant performance enhancement of the SRC-based robust MPC, and compared with the conventional MPC, it provides nearly 30% reduction of total harmonic distortion (THD) in stator phase current.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Improved Control Strategy for Fault-Tolerant Flux-Switching
           Permanent-Magnet Machine Under Short-Circuit Condition
    • Authors: Yu Wang;Liang Geng;Wenjuan Hao;Wenyan Xiao;
      Pages: 4536 - 4557
      Abstract: Fault-tolerant flux-switching permanent magnet (FTFSPM) machines are suitable for high-reliability applications owing to their good fault-tolerant capability and relatively high torque density. Under a short-circuit fault, the torque ripple caused by the short-circuit current of the FTFSPM machine affects the steady-state performance of the system; in addition, the traditional proportional–integral (PI) controller of the speed loop can hardly guarantee the optimal dynamic performance of the speed. In this study, to solve these two problems, an improved control strategy that can offer two improvements for the FTFSPM machine under the short-circuit condition is investigated. As the first improvement, on the basis of analysis of the torque ripple caused by the short-circuit current, the feed-forward control is employed to reduce the torque ripple. As the second improvement, on the basis of analysis of the influence of the speed loop PI parameters on the system dynamic performance, a torque integral balance-control method is proposed. This algorithm can make the speed and the electromagnetic torque converge simultaneously after only one adjustment of the speed. Thus, the best possible dynamic response for the speed can be achieved. Experimental results verify the correctness and effectiveness of the improved control strategy.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Inductor Current Feedback Active Damping Method for Reduced DC-Link
           Capacitance IPMSM Drives
    • Authors: Nannan Zhao;Gaolin Wang;Rongchi Zhang;Binxing Li;Yin Bai;Dianguo Xu;
      Pages: 4558 - 4568
      Abstract: The LC resonance between the line inductor and the dc-link film capacitor is an important concern in the reduced dc-link capacitance interior permanent magnet synchronous motor drive system. In this paper, an active damping method based on the virtual damping resistor is applied to suppress the LC resonance and improve the drive system stability. The performance of the damping resistor is analyzed in a systematic level, and possible configurations have been analyzed to obtain the optimal solution, which is proved to be the inductor current feedback (ICF) damping method. In order to realize the equivalent damping effect, the dc-link voltage feedback is applied to emulate the ICF-based active damping method by a step-by-step approach. Meanwhile, the grid voltage distortion will stimulate additional harmonics of the grid current in the reduced dc-link capacitance motor drives. Hence a feedforward compensation method is applied to suppress the grid current distortion arising from the distorted grid voltage, which has not been investigated in the previous related researches. Harmonics of the grid current are reduced and requirements of EN61000-3-2 can be satisfied by applying the proposed method. Experiments on a compressor drive platform equipped with the reduced dc-link capacitance are performed to verify the effectiveness of the proposed method.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Four-Leg Converter for Reluctance Machine With DC-Biased Sinusoidal
           Winding Current
    • Authors: An Li;Dong Jiang;Wubin Kong;Ronghai Qu;
      Pages: 4569 - 4580
      Abstract: This paper proposes a novel four-leg converter topology and the corresponding SVPWM strategy for a reluctance machine with DC-biased sinusoidal winding current. Compared with the traditional open-winding inverter topology, the number of the power devices and gate driver required for the four-leg converter topology are reduced by one-third, and the power loss is reduced. With the proposed four-leg converter, the cost of the motor drive is reduced and the power density is improved. The vector control and modulation models of the proposed four-leg converter are presented to control the winding current with both AC and DC components. With the proposed four-leg SVPWM strategy, the four-leg converter can achieve the same DC voltage utilization as an open-winding inverter. In addition to the ability to generate αβ-axis voltages, as same with conventional SVPWM, the proposed SVPWM can also generate γ-axis voltages without generating additional zero-sequence alternating voltages on the stator windings. The validity of the proposed converter and the corresponding modulation strategy has been demonstrated by simulation and experiment. The power loss and performance of the four-leg converter are compared with the traditional converter. Contrasting experiments show that the proposed topology can reduce power loss by about 15% at rated operation and achieve the same performance as open-winding inverters.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Gopinath Model-Based Voltage Model Flux Observer Design for Field-Oriented
           Control of Induction Motor
    • Authors: Gwon-Jae Jo;Jong-Woo Choi;
      Pages: 4581 - 4592
      Abstract: For field-oriented control (FOC) of induction motors, accurate estimation of flux is important. Among the various flux estimation methods, the voltage model flux observer exhibits superior performance in situations where there is detuning of rotor parameters, such as rotor resistance and mutual inductance, because this model is robust to the detuning of these parameters. However, it is difficult to implement the voltage model, which includes pure integration, because of the dc saturation and dc drift problems. A number of methods have been developed to overcome this problem, including the Gopinath model flux observer, which can completely solve these problems. However, this model has a critical weakness in terms of parameter sensitivity in the mid-speed region because of the property of its characteristic function. In this paper, an analysis of parameter sensitivity of existing flux observers is discussed. A method for a voltage model flux observer design based on the Gopinath model is presented. Through an analysis of the characteristic function of the observer, the voltage model is designed. Finally, the operation of the proposed method is proven by simulations and experiments.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Improved Closed-Loop Flux Observer Based Sensorless Control Against System
           Oscillation for Synchronous Reluctance Machine Drives
    • Authors: Dong Wang;Kaiyuan Lu;Peter Omand Rasmussen;
      Pages: 4593 - 4602
      Abstract: Flux-linkage based sensorless control method is well-known and has been widely used in the control of electrical machines. The closed-loop flux observer (CLFO), which is the adaptive combination of the machine voltage and current models, is commonly adopted. It can cover a wide speed operation range and was considered to be able to solve the dc drift and initial value problem associated to the pure integrator used in the observer. However, it is reported in this paper that this popular CLFO cannot always work as expected. In some situations, dc-offsets cannot be removed by this flux observer, causing large system oscillation at fundamental frequency and is very harmful to the drive system. This important issue has not been reported and discussed in the existing literatures of the CLFO. In this paper, this phenomenon is experimentally illustrated and solution to damp this harmful oscillation is proposed and verified experimentally on a synchronous reluctance machine drive system.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • A Non-Segmented PSpice Model of SiC mosfet With
           Temperature-Dependent Parameters
    • Authors: Hong Li;Xingran Zhao;Kai Sun;Zhengming Zhao;Guoen Cao;Trillion Q. Zheng;
      Pages: 4603 - 4612
      Abstract: A non-segmented PSpice model of silicon carbide metal-oxide semiconductor field effect transistor (SiC mosfet) with temperature-dependent parameters is proposed in this paper, which can improve the model's convergence and temperature characteristics. The non-segmented equations and the parameter-extraction method for the proposed SiC mosfet PSpice model are introduced first. Simulation and experiment results are given to verify the correctness of the model while considering the temperature-dependent parameters. The static characteristics of the model are verified by comparing the simulation curves with the static characteristic curves in the SiC mosfet's datasheet, and its dynamic characteristics are verified by comparing the simulation results with experimental results under different ambient temperatures (25, 75, and 125 °C) based on a double-pulse test platform. Moreover, the proposed non-segmented model, the conventional segmented model, and the model from the manufacturer are adopted and simulated in a full-bridge inverter. The simulation results show better convergence of the proposed non-segmented model. Therefore, an accurate and practical simulation model of SiC mosfet is provided for circuit design in this paper.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • A Smart IGBT Gate Driver IC With Temperature Compensated Collector Current
           Sensing
    • Authors: Jingxuan Chen;Wei Jia Zhang;Andrew Shorten;Jingshu Yu;Masahiro Sasaki;Tetsuya Kawashima;Haruhiko Nishio;Wai Tung Ng;
      Pages: 4613 - 4627
      Abstract: Conventional insulated gate bipolar transistor (IGBT) current sensing and protection techniques usually employ discrete sensors, such as lossy shunt resistors, and may involve accessing the high-voltage collector load of the IGBT. This would normally present difficulties for integration. This paper presents an IGBT gate driver IC with a collector current sensing circuit and an on-chip CPU for local data processing. This IC is prototyped using a TSMC 0.18 μm 40 V BCD Gen-2 process. The collector current sensing technique is based on the unique Miller plateau relationship between the gate current and collector current ($I_{C}$ and $I_{G}$) for a particular gate resistance ($R_{G}$). It allows a cycle-by-cycle measurement of IC during both turn-on and turn-off transients without any extra discrete components. The temperature variation is compensated internally by the on-chip CPU using polynomial curve fitting. This technique only monitors the low-voltage signal at the gate terminal, without the need to handle any high-voltage signal on the collector/load side. Measurements using a double pulse test setup show an accuracy of ±0.5 A over the current ranges of 1–30 A for turn-on and 1–50 A for turn-off from 25 to 75 °C.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Robust Flux Estimation Method for Linear Induction Motors Based on
           Improved Extended State Observers
    • Authors: Wei Xu;Renjun Dian;Yi Liu;Dong Hu;Jianguo Zhu;
      Pages: 4628 - 4640
      Abstract: Flux estimation is of great importance for high-performance linear induction motor (LIM) drives. However, due to the end effects of LIMs, range of variation in mutual inductance and secondary resistance is quite high with the change in operating condition, and the flux estimation suffers from these LIM parameter variations. To alleviate the influence of these parameter variations, this paper proposes a new flux estimation algorithm based on two improved extended state observers (ESOs) with expanded bandwidth for observing disturbances. One of them is especially designed to observe the ac disturbance at certain frequency. Taking advantage of the improved ESOs, the robustness of the flux observer to parameter deviations can be significantly strengthened, and the vector control strategy based on this new flux observer can achieve better dynamic performance. Finally, the effectiveness of the proposed method is validated by both simulation and experimental results on an LIM prototype.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Three-Dimensional Frequency-Dependent Thermal Model for Planar
           Transformers in LLC Resonant Converters
    • Authors: Rouhollah Shafaei;Martin Ordonez;Mohammad Ali Saket;
      Pages: 4641 - 4655
      Abstract: In this paper, a thorough thermal analysis is carried out in order to find an analytical three-dimensional (3-D) frequency-dependent thermal model of planar transformers (PTs) used in high-frequency power converters. Because of the tendency of having higher power density as well as miniaturization of power converters, the components have to work near their thermal limit margins. This issue is more critical for planar magnetics in LLC converters due to their variable high-frequency operation, making thermal modeling and heat transfer analysis tools necessary. The proposed 3-D frequency thermal model is obtained based on the lumped parameters network (LPN) according to different thermal resistances of the PT including convection, conduction, and radiation heat exchanges. It should be noted that not only the 3-D geometry effect of the core is applied to the proposed model, but thermal surface resistances are also considered to model the high-frequency operation effect. Moreover, the lumped capacitance thermal model is used to analyze the transient thermal variation of the transformer. The LLC resonant converter with two PTs, including EE58/11/38 and ER51/10/38 planar cores, is considered to show the compatibility of the proposed 3-D-frequency LPN model. In addition, the temperature distribution of different parts of the transformers is evaluated using finite element method modeling and compared with the proposed 3-D frequency-dependent LPN model. Experimental results confirm the improved accuracy of the proposed LPN model and show the proposed model predicts the temperature distribution in PTs with an error of less than 3%. Considering the improved accuracy and low computational time of the method, the proposed 3-D frequency-dependent model is a powerful and fast design tool to evaluate the temperature distribution for different designs, and so can be used to effectively optimize the transformer from thermal point o- view.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Mitigation of Gap Losses in Nanocrystalline Tape-Wound Cores
    • Authors: Gerardo Calderon-Lopez;Yiren Wang;Andrew J. Forsyth;
      Pages: 4656 - 4664
      Abstract: A split-core technique is proposed to mitigate the gap losses in high-frequency nanocrystalline cores, which enables significant size reductions in thermally limited designs. Finite element analysis is used to examine the gap loss dependence on core width D revealing a nonlinear relationship of the form loss ∝ $D^{alpha }$. α is approximately constant for frequencies of 10–200 kHz over the range of core widths typically used in power electronics, but α increases with gap length. Splitting the core into a number of subcores can therefore provide significant reductions in gap loss, especially with larger gap lengths. The results from a 300-A (peak), 200-A (continuous) inductor show that with three subcores and a gap length of 4 mm, the gap losses are reduced by 50%, and the hot-spot temperature is reduced by 24.5 °C. Using the technique it is estimated that the original inductor weight could be reduced by 40% with four split cores, making a significant impact on converter power density.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Mission Profile Based Reliability Evaluation of Capacitor Banks in Wind
           Power Converters
    • Authors: Dao Zhou;Yipeng Song;Yang Liu;Frede Blaabjerg;
      Pages: 4665 - 4677
      Abstract: With the increasing penetration of wind power, reliable and cost-effective wind energy production is of more and more importance. The doubly-fed-induction-generator-based turbine system is widely used and dominates the wind market. In this paper, an analytical approach to assess reliability for power capacitors, both the dc-link capacitor bank and ac-side filter capacitor bank, is presented considering the annual mission profile. Based on the electrical behavior at various loading conditions, the lifecycle of the single power capacitor can be predicted through its electrothermal stresses. This percentile lifetime can be translated to the Weibull lifetime distribution of the power capacitor by considering the parameter uncertainties and tolerance variations. Thereafter, a reliability block diagram is used to bridge the reliability curves from the component-level of the individual capacitor to the system-level of the capacitor bank. A case study of a 2-MW wind turbine shows that the lifecycle is significantly reduced from the individual capacitor to the capacitor bank, where the dc-link capacitor bank dominates the lifetime consumption. Furthermore, the electrical stresses of the power capacitors are experimentally verified at a down-scaled 7.5 kW prototype.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Circuit Models and Fast Optimization of Litz Shield for
           Inductive-Power-Transfer Coils
    • Authors: Ming Lu;Khai D. T. Ngo;
      Pages: 4678 - 4688
      Abstract: The metal shields with plates or rings are usually added to the inductive-power-transfer coils to attenuate the stray magnetic field. However, the coil-to-coil efficiency is reduced owning to the extra losses on the shields. This paper introduces the litz shield which attenuates the field with smaller shielding loss thanks to the uniform distribution of the shield current. Two types of litz shields, i.e., shorted litz shield and driven litz shield are discussed in detail. Their performances are analyzed with the circuit model composed of four coupled inductors. The efficiency and the field attenuation for the coils with litz shields are optimized with Pareto fronts. A fast method to derive the fronts using a lumped-loop model is described. Only tens of finite-element simulations are required in the entire optimization. The coils with different shields were optimized to transfer 100-W power across 40-mm gap with the same efficiency. The measurement results prove that the shorted litz shield is more effective than the other shields. It attenuated 23% more of the stray magnetic field compared to the coils with traditional metal shield.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Circuit Theoretic Considerations of LED Driving: Voltage-Source Versus
           Current-Source Driving
    • Authors: Zheng Dong;Chi K. Tse;S. Y. Ron Hui;
      Pages: 4689 - 4702
      Abstract: Light-emitting diodes (LEDs) are solid-state devices with specific $v$–$i$ characteristics. In this paper, we study the basic requirement of the driving circuits and discuss the proper approach to drive LEDs in view of their characteristics. We compare voltage source driving and current source driving, and discuss their relative advantages and constraints. We specifically introduce the use of circuit duality principle for developing new current-source-mode (CSM) drivers that are less known but are theoretically more versatile compared to their conventional voltage-source-mode counterparts. The study highlights the effects of the choice of driving circuits in terms of the number and size of circuit components used, duty cycle variation, sensitivity of control, nonlinearity and control complexity of LED drivers. We propose a CSM single-inductor multiple-output (SIMO) converter, which demonstrates the advantage of having inductorless and easily controlled current-source drivers, and present a comparison of the CSM SIMO converter with the existing SIMO converters. We further illustrate that a high-voltage-step-down ratio can be naturally achieved by the CSM high-voltage-step-down converter without the use of transformers. This paper presents a systematic and comparative exposition of the circuit theory of driving LEDs, with experimental evidence supporting the major conclusions.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • A Neural Network Based Approach to Simulate Electrothermal Device
           Interaction in SPICE Environment
    • Authors: Diego Chiozzi;Mirko Bernardoni;Nicola Delmonte;Paolo Cova;
      Pages: 4703 - 4710
      Abstract: An innovative modeling methodology for the simulation of electrothermal interaction in power devices, based on neural networks (NNs), is shown. The suitability of NNs in modeling the complicated nonlinear, temperature dependent characteristic that power electronics devices feature is shown. The proposed methodology is particularly suited to be implemented in electrical simulators. The approach can be divided in two parallel steps: first, NNs are used to describe the complex, highly nonlinear electrothermal characteristic of the considered device; and second, a nonlinear RC-based thermal model is generated, with a method published in a previous work. These two subsystems are coupled together in order to achieve a self-consistent electrothermal model. The modeling results are validated against experiments with very satisfactory results. The technique is explained in detail; advantages and limitations of the method are then discussed.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Reference Submodule Based Capacitor Monitoring Strategy for Modular
           Multilevel Converters
    • Authors: Fujin Deng;Qingsong Wang;Dong Liu;Yanbo Wang;Ming Cheng;Zhe Chen;
      Pages: 4711 - 4721
      Abstract: The modular multilevel converter (MMC) is attractive for medium- or high-power applications because of the advantages of its high modularity, availability, and high power quality. Reliability is one of the most important challenges for the MMC consisting of a large number of submodules (SMs). The capacitor monitoring is one of the important issues in the MMC. This paper proposed a reference submodule (RSM)-based capacitor monitoring strategy for the capacitance estimation in the MMC, where the capacitances in the monitoring SMs can be estimated based on the capacitor voltage relationship between the RSM and the monitoring SMs. The proposed monitoring strategy does not rely on the information of all capacitor voltage and current, which effectively simplifies the algorithm for capacitance estimation. The simulation studies with the time-domain professional tool PSCAD/EMTDC are conducted and a down-scale MMC prototype is also tested in the laboratory with the proposed capacitor monitoring strategy. The study results confirm the effectiveness of the proposed capacitor monitoring strategy.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Experimental Investigation of Linear Cumulative Damage Theory With Power
           Cycling Test
    • Authors: Guang Zeng;Christian Herold;Torsten Methfessel;Marc Schäfer;Oliver Schilling;Josef Lutz;
      Pages: 4722 - 4728
      Abstract: In this paper, several power cycling tests under single or combined test conditions were undertaken to investigate the applicability of linear cumulative damage theory in the lifetime prediction of power semiconductor devices. The validity of this theory was verified by an experimental method for one lifetime limit, which is an increase of forward voltage at load current by 5%. The corresponding failure mechanism is the degradation of bond wire contacts.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • A Comprehensive Review Toward the State-of-the-Art in Failure and Lifetime
           Predictions of Power Electronic Devices
    • Authors: Abu Hanif;Yuechuan Yu;Douglas DeVoto;Faisal Khan;
      Pages: 4729 - 4746
      Abstract: This paper discusses various types of failure mechanisms, precursor parameters, and accelerated aging-based procedures to estimate the remaining life of power electronic devices. Special attention has been given to summarize the different techniques typically used for measuring the junction temperature, because it plays a vital role during accelerated aging and condition monitoring. We reviewed more than 250 papers, and the references list 139 of them in order to explain and address the advantages and disadvantages of various techniques toward the reliability prognosis. Thus, this paper can be considered as an expedient reference to conduct future research on lifetime prediction of existing power electronic devices.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Short-Circuit Fault Diagnosis Based on Rough Sets Theory for a
           Single-Phase Inverter
    • Authors: André Barros de Mello Oliveira;Robson Luiz Moreno;Enio Roberto Ribeiro;
      Pages: 4747 - 4764
      Abstract: The short-circuit (SC) fault diagnosis in inverters is an important procedure for the continuity of the performance and the extension of its useful life. The methods of diagnosis of SC failures produce good results, however, they present unfavorable aspects: they detect only one of the faults of SC, that is to say, the hard switch fault (HSF) or the fault under load (FUL); depend on switch parameters; and use artificial intelligence (AI) techniques in their algorithms, which are executed simultaneously with the inverter operation. This article presents a method of diagnosing SC faults performed with a digital circuit. The proposed method identifies short-circuit faults: HSF and FUL; can be used with any switch, regardless of its parameters; and does not use AI algorithms and techniques concurrently with inverter operation. The digital diagnostic circuit is obtained with the use of rough sets theory (RST), which optimizes and defines a minimum set of variables necessary to diagnose faults. Applying RST to the variables obtains a set of diagnostic rules. These rules are performed with basic logic functions and, for this reason, a digital diagnostic circuit is obtained. The diagnostic variables are the command signals and the voltage source inverter switches currents. The simulation and experimental results validate the shown diagnostic method.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Extraction of Intrinsic Parameters of Lead–Acid Batteries Using
           Energy Recycling Technique
    • Authors: Chun-Sing Cheng;Ricky Wing-Hong Lau;Nand Kishor Rathi;Henry Shu-Hung Chung;
      Pages: 4765 - 4779
      Abstract: This paper presents the use of an energy recycling technique to extract the intrinsic parameters of lead–acid batteries. The charging and discharging currents of the battery under test are programmed by controlling a bidirectional dc–dc converter to profile the power flow between the battery and a supercapacitor. The sampled battery voltage and current information over the charging and discharging periods are used to estimate the parameters of a high-order electrical battery model with a modified particle swarm optimization algorithm and compare with the battery voltage and current predicted with the extracted parameters.  With the energy recycling mechanism, the proposed parameter extraction process is environment friendly and has low power dissipation, thus increasing the power handling density and allowing long testing duration. A prototype that can extract the intrinsic parameters of eight different types of 12 V, 130 A lead–acid batteries has been built. Its performance has been evaluated with different charging and discharging profiles. The estimated parameters are favorably verified with the theoretical predictions, results obtained by the extended Kalman filter method, and results obtained on a calibrated commercial battery testing system. Results reveal that testing batteries with both charging and discharging processes gives a more accurate prediction of battery performance.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Control Strategy of Single-Phase Active Front-End Cascaded H-Bridge Under
           Cell Fault Condition
    • Authors: Yoon-Ro Lee;Jeong-Mock Yoo;Hyun-Sam Jung;Seung-Ki Sul;
      Pages: 4780 - 4793
      Abstract: Cascaded H-bridge (CHB) inverter is the most widely used topology for a medium-voltage drive system due to the high degree of modularity, easier implementation of medium output voltage, and the ability to continuous operation under the cell fault condition. Because each power cell of CHB should have isolated dc source, multiwinding input transformer and three-phase active front end (AFE) are generally used for regenerative applications. The whole system can be simplified by replacing the three-phase AFE with single-phase AFE. However, if the control strategy of normal operation is adopted under the cell fault condition, input power imbalance among three phases inevitably occurs. In that situation, not only faulty cells, but also some unscathed cells should be excluded with giving up the maximum capability of the system, not to deteriorate grid current. This paper proposes a control scheme against the cell fault condition of the single-phase AFE CHB. By applying the proposed control scheme to the system, dc-link voltage of each cell and grid current are well regulated without imbalance even under the cell fault conditions. Finally, it can minimize the number of undamaged cells which should be turned off and maximize the capability of the system under the cell fault condition. Simulation and experimental results are provided to verify the effectiveness of the proposed scheme.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Analysis of an Online Stability Monitoring Approach for DC Microgrid Power
           Converters
    • Authors: Aram Khodamoradi;Guangyuan Liu;Paolo Mattavelli;Tommaso Caldognetto;Paolo Magnone;
      Pages: 4794 - 4806
      Abstract: An online approach to evaluate and monitor the stability margins of dc microgrid power converters is presented in this paper. The discussed online stability monitoring technique is based on the Middlebrook's loop-gain measurement technique, adapted to the digitally controlled power converters. In this approach, a perturbation is injected into a specific digital control loop of the converter and after measuring the loop gain, its crossover frequency and phase margin are continuously evaluated and monitored. The complete analytical derivation of the model, as well as detailed design aspects, are reported. In addition, the presence of multiple power converters connected to the same dc bus, all having the stability monitoring unit, is also investigated. An experimental microgrid prototype is implemented and considered to validate the theoretical analysis and simulation results, and to evaluate the effectiveness of the digital implementation of the technique for different control loops. The obtained results confirm the expected performance of the stability monitoring tool in steady-state and transient operating conditions. The proposed method can be extended to generic control loops in power converters operating in dc microgrids.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Energy Feedback Control of Light-Load Voltage Regulation for
           LLC Resonant Converter
    • Authors: Zhijian Fang;Junhua Wang;Rong Liu;Liangle Xiao;Junkun Zhang;Guozhen Hu;Qisheng Liu;
      Pages: 4807 - 4819
      Abstract: An LLC resonant converter would have light-load voltage regulation problems due to the effect of parasitic capacitances in a high-frequency range. In this paper, an energy feedback control method is proposed to improve the light-load regulation capacity by using synchronous rectifiers (SRs). The SR bridges are controlled ahead of the primary inverter bridges to deliver the energy from load to source, reducing the output voltage independent of the load. Then the desired voltage can be achieved even in no-load conditions by regulating the operation time of the energy feedback mode. The gain, voltage ripple, and efficiency performances of the proposed control method are discussed based on the precise analysis and an accurate model of the converter. Moreover, the light-load operations of the LLC resonant converter are analyzed deriving the critical load condition. Finally, the proposed control method is verified by the experiments of a 12 V/8 A LLC resonant converter prototype.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Novel Space Vector Pulsewidth Modulation Strategies for Single-Phase
           Three-Level NPC Impedance-Source Inverters
    • Authors: Tatiana E. Shults;Oleksandr Husev;Frede Blaabjerg;Carlos Roncero-Clemente;Enrique Romero-Cadaval;Dmitri Vinnikov;
      Pages: 4820 - 4830
      Abstract: This paper presents new space vector pulsewidth modulation (PWM) strategies for a single-phase three-level buck-boost neutral point clamped inverter coupled with impedance-source (IS) network. These strategies can be implemented for systems with any IS network with neutral point. The case study system is based on the quasi-Z-source inverter with continuous input current. To demonstrate an improved performance, the strategies are compared with a traditional PWM strategy. The advantages lie in reduced switching number, without output voltage quality distortion. The simulation and experimental results confirm the theoretical predictions.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Parameter Identification and Maximum Power Estimation of
           Battery/Supercapacitor Hybrid Energy Storage System Based on Cramer–Rao
           Bound Analysis
    • Authors: Ziyou Song;Jun Hou;Heath F. Hofmann;Xinfan Lin;Jing Sun;
      Pages: 4831 - 4843
      Abstract: This paper presents the analysis, design, and experimental validation of parameter identification of battery/supercapacitor (SC) hybrid energy storage system (HESS) for the purpose of condition monitoring and maximum power estimation. The analytic bounds on the error of battery and SC parameter identification, considering voltage measurement noise, are obtained based on the Fisher information matrix and Cramer–Rao bound analysis. The identification of different parameters requires different signal patterns to ensure high accuracy, rendering tradeoffs in the multiparameter identification process. With an appropriately designed current profile, HESS parameters are identified using recursive least squares with a forgetting factor. The identified parameters are then used to estimate the maximum power capability of the HESS. The maximum power capabilities of the battery and SC are estimated for both 1 and 30 s time horizons. The parameter identification algorithm can be applied to systems including either batteries or SCs when the optimal excitation current can be injected. Experimental validation is conducted on an HESS test-bed, which shows that the proposed algorithm is effective in estimating the HESS maximum power based on appropriate current excitation.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Modular Multilevel Series/Parallel Converter With Switched-Inductor Energy
           Transfer Between Modules
    • Authors: Ricardo Lizana F.;Sebastian Rivera;Zhongxi Li;Jenny Luo;Angel V. Peterchev;Stefan M. Goetz;
      Pages: 4844 - 4852
      Abstract: This paper presents a modular multilevel series/parallel converter (MMSPC) with intermodule switched-inductor power transfer. The switched-inductor voltage conversion feature allows controllable and efficient transfer of energy between modules with nonnegligible voltage difference, providing both step-down and step-up functionalities. Thus, this converter can accurately control and rapidly adjust the voltage of each module to generate an ac output voltage waveform with a controllable number of levels, increasing the quality of the output. Moreover, the intrinsic dc–dc conversion feature can generate a dc controllable output voltage and enable new applications. In this text, we specifically demonstrate how the flexibility of obtaining both ac and dc output with the same setup renders the topology promising for battery energy storage systems and dc microgrid applications. Experimental results validate the topology and concept of an MMSPC with intrinsic switched-inductor conversion.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Current Harmonic Reduction Based on Space Vector PWM for DC-Link
           Capacitors in Three-Phase VSIs Operating Over a Wide Range of Power Factor
           
    • Authors: Koroku Nishizawa;Jun-Ichi Itoh;Akihiro Odaka;Akio Toba;Hidetoshi Umida;
      Pages: 4853 - 4867
      Abstract: This paper proposes a novel space vector pulsewidth modulation (SVPWM) strategy to reduce the switching-frequency-order inverter input current harmonics for a two-level three-phase voltage-source inverter operating over a wide range of the load power factor. The fluctuation of the inverter input current around its average value is minimized by optimization of the utilized voltage space vectors to reduce the inverter input current harmonics, which extends the lifetime of the dc-link electrolytic capacitors. Furthermore, the proposed strategy can be adapted to a motor drive system, where a wide variation of the load power factor is desired, by changing the optimized combinations of the voltage space vectors according to the polarities of the output phase currents. Experiments with the application of the novel SVPWM confirm that the inverter input current harmonics is reduced by up to 29.5% compared to that with the conventional SVPWM strategy. Moreover, the analytical and experimental results confirm that the proposed SVPWM reduces the inverter input current harmonics in both driving mode and regenerative braking mode, as well as with any load power factor.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Predictive Duty Cycle Control With Reversible Vector Selection for
           Three-Phase AC/DC Converters
    • Authors: Xiaolong Shi;Jianguo Zhu;Li Li;Dylan Dah-Chuan Lu;Jianwei Zhang;Haitao Yang;
      Pages: 4868 - 4882
      Abstract: The conventional predictive duty cycle control (CPDCC) of three-phase full-bridge ac/dc converters selects adjacent nonzero vector pair based on the grid-voltage vector location, then the duration for each vector is calculated. Though the vector selection method is quite simple, it has a significant disadvantage that the values of calculated durations could be frequently less than zero due to nonoptimal vector selection, which results in high current harmonics and power notches. It could be improved with improved predictive duty cycle control (IPDCC) by reselecting the nonzero vector pair when negative duration exists; however, the whole vector selection and calculation procedure are repeated. By theoretical verification that the power variation rates of reversible vector pair are symmetrical with respect to that of zero vector, this paper proposes the reversible predictive duty cycle control (RPDCC) simply by replacing the original vector with its opposite vector and the recalculation of vector duration is eliminated compared with IPDCC. Thus, the calculation effort is almost not increased compared with CPDCC while system performance is significantly improved. The proposed control is theoretically derived and verified with the simulation and experimental results showing that RPDCC has better steady and dynamic performance than CPDCC and IPDCC methods.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • An Inductor Current Estimator for Digitally Controlled Synchronous Buck
           Converter
    • Authors: Rajat Channappanavar;Santanu K Mishra;R. K. Singh;
      Pages: 4883 - 4894
      Abstract: Inductor current is an important feedback parameter in synchronous buck converters (SBCs). It is used for overcurrent protection, current sharing among interleaved modules, and current-mode feedback regulation, among others. While implementing a digital controller, inductor current is sensed and fed into the controller through a high sampling frequency analog to digital converter (ADC). As the switching frequency of the converter becomes higher, the need for an even higher sampling frequency ADC also goes up, which is a distinct disadvantage in terms of the overall cost. This paper discusses a simple current estimation technique that avoids use of any expensive current sensor and high sampling frequency ADCs. The paper shows that in a buck converter, inductor current can be estimated by tracking the width of the switch node voltage. Implementation and limitations of the proposed current estimation scheme are discussed in detail. The proposed method is validated using a 3.3 V–15 A SBC prototype and results show the estimation technique is accurate within 5% with a converter switching frequency of 800 kHz. In order to prove the effectiveness of the technique in feedback regulation, the current estimation technique is used to implement average current mode and hysteretic current mode control on a SBC. To prove the effectiveness of the proposed current estimation scheme, it is used in closed-loop control of the SBC to verify the dynamic responses, such as start-up transient, step change in load, and reference.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • High-Stability Position-Sensorless Control Method for Brushless DC Motors
           at Low Speed
    • Authors: Tuanjie Li;Jiaxing Zhou;
      Pages: 4895 - 4903
      Abstract: In order to improve the stability of brushless DC (BLDC) motors at low speed, a high-stability position-sensorless control method is proposed in this paper. Because the back electromotive force (EMF) is very small at low speed, a novel algorithm is proposed to detect the zero crossing point of back EMF accurately. First, the line-to-line back EMF is computed based on the mathematical model of BLDC motors. Then, a low-pass filter (LPF) with alterable cutoff frequency is used to reduce the disturbance of the line-to-line back EMF. Last, the commutation signal is obtained by detecting the zero crossing point (ZCP) of the line-to-line back EMF. However, the commutation signal is delayed by the LPF. For this reason, based on the three-phase back EMF, a novel compensation algorithm including an open loop and a close loop is proposed to compensate for commutation error. Moreover, the speed feedback has a big delay at low speed. According to this, a novel speed calculation algorithm is presented to decrease the delay. Both the simulation and experimental results validate the high stability and reliability of the proposed method.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Inductance-Independent Nonlinearity Compensation for Single-Phase
           Grid-Tied Inverter Operating in Both Continuous and Discontinuous Current
           Mode
    • Authors: Hoai Nam Le;Jun-Ichi Itoh;
      Pages: 4904 - 4919
      Abstract: This paper proposes a control for a single-phase grid-tied inverter operating in both continuous current mode (CCM) and discontinuous current mode (DCM) to minimize inductors without worsening a current total harmonic distortion (THD). In a conventional CCM/DCM control, an inductance is required in a DCM nonlinearity compensation; consequently, the control becomes inductance-dependent. In the proposed control, a duty ratio at a previous calculation period is utilized to compensate for the DCM nonlinearity and detect current modes independently from the inductance. A 4-kW 100-kHz prototype of the inverter with two designs of the inductor is realized to confirm the effectiveness of the proposed control. When the inductor impedance, which is normalized by an inverter impedance, is reduced from 1.8% to 0.5%, volume and material cost of the inductor are reduced by 51% and 62%, respectively, whereas the loss at a light load of 0.1 p.u. is reduced by 35%. However, due to this inductor minimization, the current THD at a rated load increases from 2.3% to 8.7% with the conventional control, violating the grid current harmonic constraint regulated by standard IEEE-1547. The proposed CCM/DCM control reduces the current THD from 8.7% to 2.1%, enabling the inductor minimization and satisfies the grid standard.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Approximate Discrete-Time Small-Signal Models of DC–DC Converters With
           Consideration of Practical Pulsewidth Modulation and Stability Improvement
           Methods
    • Authors: Xin Li;Xinbo Ruan;Xiaoling Xiong;Mengke Sha;Chi K Tse;
      Pages: 4920 - 4936
      Abstract: It is generally known that averaged models are inadequate in describing the effects of leading-edge and trailing-edge pulsewidth modulation (PWM) on the stability of dc–dc converters. In this paper, using discrete-time models of the buck, boost, and buck–boost converters and considering the effects of leading-edge and trailing-edge PWM, the general expressions of the duty-cycle-to-output-voltage transfer function, Gvd(z), in the discrete-time domain are derived. Based on the low-pass characteristics of the dc-dc converters and related properties of the matrix functions, approximate expressions of Gvd in the frequency domain are derived, which are simple and accurate up to half the switching frequency. Using the approximate Gvd, the stability of the three basic dc–dc converters under leading-edge and trailing-edge PWM is analyzed. It is shown that the stability of the buck converter is unaffected by the type of PWM, while the leading-edge modulated boost and buck–boost converters have better stability than the trailing-edge modulated ones. Since the trailing-edge modulation is commonly available in PWM controller integrated circuits, the modulation signal zero-order holding (ZOH) method and the inductor current feedback control method are proposed for use in the trailing-edge modulated boost and buck–boost converters to achieve the same effect of leading-edge modulated converters. Experimental buck and boost converters were constructed for verification of the accuracy of the proposed model and the validity of the proposed control schemes.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Quasi-Resonant Control for Harmonic Current Suppression of a Magnetically
           Suspended Rotor
    • Authors: Peiling Cui;Guoxi Zhang;Zhiyuan Liu;Han Xu;
      Pages: 4937 - 4950
      Abstract: In the magnetically suspended rotor (MSR) system of the flywheel, harmonic current produced mainly by mass imbalance and sensor runout would cause undesirable harmonic vibration. Resonant control (RSC) is one of the remarkable performance alternatives for rejecting a set of selected frequency components of the periodic disturbance in a control system. Based on the intrinsic relationship between RSC and repetitive control, which is deduced and clarified, this paper proposes a novel quasi-resonant control (QRSC) scheme for a baseline prestable MSR system to suppress the harmonic current. By introducing a damping factor, QRSC achieves a good balance between stability and dynamic performance. With hybrid phase compensation, it provides system absolute stability and expands the stability margin of the MSR system. Further, as the domination of harmonic current, low-order frequency components are suppressed by parallel QRSCs (PQRSC). A stability criterion with rigorous proof for the plug-in PQRSC-controlled MSR system is addressed as well. Experimental results obtained with a magnetically suspended flywheel prototype corroborate the theoretical approach.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Virtual Positive-Damping Reshaped Impedance Stability Control Method for
           the Offshore MVDC System
    • Authors: Leming Zhou;Wenhua Wu;Yandong Chen;Zhixing He;Xiaoping Zhou;XuCheng Huang;Ling Yang;An Luo;Josep M. Guerrero;
      Pages: 4951 - 4966
      Abstract: For the offshore medium-voltage direct-current (MVdc) system, the dc-side medium voltage can easily cause high-frequency oscillation and even instability owing to the complex impedance interactions. The virtual-resistance stability control method aiming at rectifier station is first introduced from low-voltage dc micro-grid application for mitigating its dc-side oscillation without affecting the load performance of the inverter station. Viewed from the dc input terminal, the small-signal dc impedance modeling of the overall system is established by considering the influences of dc cable, ac grid inductance, and input-parallel output-series structure of rectifier station. Then, the oscillation mechanism is analyzed by the impedance-based Nyquist stability criterion. It is found that only the virtual resistance deteriorates the stability of the MVdc system under the low switching-frequency condition, because the high-frequency oscillation peak may easily exceed the narrow control bandwidth of the rectifier station and fall into the negative-damping region, resulting in a poor robustness against the dc cable variation. To address this issue, the virtual positive-damping reshaped impedance stability control method is further proposed to maintain a larger positive damper in the actual oscillation frequency range regardless of the variation of dc cable length. Thus, the dc-side oscillation of the offshore MVdc system is effectively mitigated at the low switching frequency. Finally, simulation and experimental results validate the proposed control method.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Modular Multilevel Converter Control Methods Performance Benchmark for
           Medium Voltage Applications
    • Authors: Alexandre Christe;Drazen Dujic;
      Pages: 4967 - 4980
      Abstract: Modular multilevel converters are increasingly being considered or used for various medium voltage applications. Multiple control methods have been proposed for the control of the direct to three-phase modular multilevel converter. They differ one from another in the way the capacitor voltage ripples are handled, i.e., either neglected, estimated, reconstructed by filtering or measured. This has implications on the performance level that can be obtained. This paper provides insights on the advantages and drawbacks of each control method, in inverter and rectifier mode, with a fair and thorough assessment supported by extensive simulations, with converter ratings that are realistic for medium voltage applications. Finally, this works highlights the impact of the higher dynamics for medium voltage direct current (dc) applications compared to high voltage dc ones on the choice of the control method.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Active SOC Balancing Control Strategy for Modular Multilevel Super
           Capacitor Energy Storage System
    • Authors: Kaitao Bi;Li Sun;Quntao An;Jiandong Duan;
      Pages: 4981 - 4992
      Abstract: This paper presents an active state-of-charge (SOC) balancing control strategy for modular super capacitor energy storage system (ESS). The strategy has a master–slave structure, including a common dc bus voltage loop and individual slave current loop for each submodule. The common voltage loop ensures the ability of the system to stabilize dc bus voltage cannot be affected by SOC balancing control, and provides a same original current reference for all submodules. SOC information is introduced into current loops to achieve SOC balancing control. The highest SOC is taken as a reference for low SOC modules, thus, the low SOC modules can regulate the submodule average operation current according to the SOC reference and their own SOC. In order to minimize system current deviation caused by the introduction of SOC, a current correction method is proposed to improve system current regulate performance. The proposed strategy can achieve SOC balancing control during ESS charging and discharging process dynamically, in addition, the modularity of the system is improved and the proposed strategy has favorable stability. A modular ESS prototype consisting of three half-bridge submodules is tested in the laboratory, and the experimental results verify the effectiveness of the proposed control strategy.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Decentralized Interleaving of Parallel-connected Buck Converters
    • Authors: Mohit Sinha;Jason Poon;Brian B. Johnson;Miguel Rodriguez;Sairaj V. Dhople;
      Pages: 4993 - 5006
      Abstract: We present a decentralized control strategy that yields switch interleaving for parallel-connected dc–dc buck converters. Compared to state-of-the-art methods that are distributed at best, the proposed architecture requires no communication, and hence, presents a variety of advantages with regard to reliability, modularity, and cost. The method is based on the digital implementation of the dynamics of a Liénard-type oscillator circuit as the controller for the converters. Each controller only requires the locally measured output current to synthesize the pulsewidth modulation (PWM) carrier waveform. The intrinsic electrical coupling between converters drives the nonlinear-oscillator-based controllers to converge to an interleaved state with uniform phase spacing across PWM carriers, independent of the number of converters, the load, and initial conditions. We provide analytical guarantees for existence and stability of the interleaved state as well as extensive hardware results for a system of five 120 W 48 V-to-12 V dc–dc buck converters that demonstrate convergence to the interleaved state in the face of a variety of large-signal disturbances.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
  • Corrections to “Model Predictive Control With Common-Mode Voltage
           Injection for Modular Multilevel Converter” [Mar 17 1767-1778]
    • Authors: Apparao Dekka;Bin Wu;Venkata Yaramasu;Navid R. Zargari;
      Pages: 5007 - 5008
      Abstract: The authors Dekka et al. proposed a model predictive control with common-mode voltage injection for modular multilevel converters in the paper published in IEEE Trans. Power Electron., vol. 32, no. 3, pp. 1767–1778, Mar. 2017. As a part of implementation and analysis, a detailed mathematical model of various current components including input current ($i_s$), output current ($i_x$), and circulating current ($i_{xz}$) are developed. During the review, we found some minor mistakes in the discrete-time model of the circulating current. In this correspondence, the authors present a detailed derivation of the revised circulating current model.
      PubDate: May 2019
      Issue No: Vol. 34, No. 5 (2019)
       
 
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
 
Home (Search)
Subjects A-Z
Publishers A-Z
Customise
APIs
Your IP address: 184.73.14.222
 
About JournalTOCs
API
Help
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-