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  Subjects -> ELECTRONICS (Total: 202 journals)
Showing 1 - 200 of 277 Journals sorted alphabetically
Acta Electronica Malaysia     Open Access  
Advanced Materials Technologies     Hybrid Journal  
Advances in Electrical and Electronic Engineering     Open Access   (Followers: 9)
Advances in Electronics     Open Access   (Followers: 99)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Power Electronics     Open Access   (Followers: 39)
Advancing Microelectronics     Hybrid Journal  
American Journal of Electrical and Electronic Engineering     Open Access   (Followers: 28)
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: 15)
Australian Journal of Electrical and Electronics Engineering     Hybrid Journal  
Batteries     Open Access   (Followers: 9)
Batteries & Supercaps     Hybrid Journal   (Followers: 4)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 31)
Bioelectronics in Medicine     Hybrid Journal  
Biomedical Instrumentation & Technology     Hybrid Journal   (Followers: 6)
BULLETIN of National Technical University of Ukraine. Series RADIOTECHNIQUE. RADIOAPPARATUS BUILDING     Open Access   (Followers: 2)
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: 9)
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: 304)
ECTI Transactions on Computer and Information Technology (ECTI-CIT)     Open Access  
ECTI Transactions on Electrical Engineering, Electronics, and Communications     Open Access   (Followers: 2)
Edu Elektrika Journal     Open Access   (Followers: 1)
Electrica     Open Access  
Electronic Design     Partially Free   (Followers: 123)
Electronic Markets     Hybrid Journal   (Followers: 7)
Electronic Materials Letters     Hybrid Journal   (Followers: 4)
Electronics     Open Access   (Followers: 108)
Electronics and Communications in Japan     Hybrid Journal   (Followers: 10)
Electronics For You     Partially Free   (Followers: 103)
Electronics Letters     Hybrid Journal   (Followers: 26)
Elkha : Jurnal Teknik Elektro     Open Access  
Energy Harvesting and Systems     Hybrid Journal   (Followers: 4)
Energy Storage     Hybrid Journal   (Followers: 1)
Energy Storage Materials     Full-text available via subscription   (Followers: 4)
EPE Journal : European Power Electronics and Drives     Hybrid Journal  
EPJ Quantum Technology     Open Access   (Followers: 1)
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)
IACR Transactions on Symmetric Cryptology     Open Access  
IEEE Antennas and Propagation Magazine     Hybrid Journal   (Followers: 100)
IEEE Antennas and Wireless Propagation Letters     Hybrid Journal   (Followers: 81)
IEEE Embedded Systems Letters     Hybrid Journal   (Followers: 56)
IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology     Hybrid Journal   (Followers: 2)
IEEE Journal of Emerging and Selected Topics in Power Electronics     Hybrid Journal   (Followers: 52)
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 Letters on Electromagnetic Compatibility Practice and Applications     Hybrid Journal   (Followers: 3)
IEEE Magnetics Letters     Hybrid Journal   (Followers: 7)
IEEE Nanotechnology Magazine     Hybrid Journal   (Followers: 42)
IEEE Open Journal of Circuits and Systems     Open Access   (Followers: 2)
IEEE Open Journal of Industry Applications     Open Access   (Followers: 2)
IEEE Open Journal of the Industrial Electronics Society     Open Access   (Followers: 2)
IEEE Power Electronics Magazine     Full-text available via subscription   (Followers: 77)
IEEE Pulse     Hybrid Journal   (Followers: 5)
IEEE Reviews in Biomedical Engineering     Hybrid Journal   (Followers: 22)
IEEE Solid-State Circuits Letters     Hybrid Journal   (Followers: 2)
IEEE Solid-State Circuits Magazine     Hybrid Journal   (Followers: 13)
IEEE Transactions on Aerospace and Electronic Systems     Hybrid Journal   (Followers: 363)
IEEE Transactions on Antennas and Propagation     Full-text available via subscription   (Followers: 74)
IEEE Transactions on Automatic Control     Hybrid Journal   (Followers: 59)
IEEE Transactions on Autonomous Mental Development     Hybrid Journal   (Followers: 8)
IEEE Transactions on Biomedical Engineering     Hybrid Journal   (Followers: 38)
IEEE Transactions on Broadcasting     Hybrid Journal   (Followers: 13)
IEEE Transactions on Circuits and Systems for Video Technology     Hybrid Journal   (Followers: 26)
IEEE Transactions on Consumer Electronics     Hybrid Journal   (Followers: 45)
IEEE Transactions on Electron Devices     Hybrid Journal   (Followers: 19)
IEEE Transactions on Geoscience and Remote Sensing     Hybrid Journal   (Followers: 221)
IEEE Transactions on Haptics     Hybrid Journal   (Followers: 4)
IEEE Transactions on Industrial Electronics     Hybrid Journal   (Followers: 76)
IEEE Transactions on Industry Applications     Hybrid Journal   (Followers: 40)
IEEE Transactions on Information Theory     Hybrid Journal   (Followers: 26)
IEEE Transactions on Learning Technologies     Full-text available via subscription   (Followers: 12)
IEEE Transactions on Power Electronics     Hybrid Journal   (Followers: 79)
IEEE Transactions on Services Computing     Hybrid Journal   (Followers: 4)
IEEE Transactions on Signal and Information Processing over Networks     Hybrid Journal   (Followers: 14)
IEEE Transactions on Software Engineering     Hybrid Journal   (Followers: 79)
IEEE Women in Engineering Magazine     Hybrid Journal   (Followers: 11)
IEEE/OSA Journal of Optical Communications and Networking     Hybrid Journal   (Followers: 16)
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 Energy Systems Integration     Open Access   (Followers: 1)
IET Microwaves, Antennas & Propagation     Hybrid Journal   (Followers: 35)
IET Nanodielectrics     Open Access  
IET Power Electronics     Hybrid Journal   (Followers: 59)
IET Smart Grid     Open Access   (Followers: 1)
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 Technology Research Journal Phranakhon Rajabhat University     Open Access  
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: 12)
International Journal of Antennas and Propagation     Open Access   (Followers: 11)
International Journal of Applied Electronics in Physics & Robotics     Open Access   (Followers: 4)
International Journal of Computational Vision and Robotics     Hybrid Journal   (Followers: 5)
International Journal of Control     Hybrid Journal   (Followers: 11)
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: 3)
International Journal of High Speed Electronics and Systems     Hybrid Journal  
International Journal of Hybrid Intelligence     Hybrid Journal  
International Journal of Image, Graphics and Signal Processing     Open Access   (Followers: 16)
International Journal of Microwave and Wireless Technologies     Hybrid Journal   (Followers: 10)
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: 25)
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: 4)
Journal of Advanced Dielectrics     Open Access   (Followers: 1)
Journal of Artificial Intelligence     Open Access   (Followers: 12)
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: 37)
Journal of Electrical Bioimpedance     Open Access  
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: 8)
Journal of Electromagnetic Waves and Applications     Hybrid Journal   (Followers: 9)
Journal of Electronic Design Technology     Full-text available via subscription   (Followers: 6)
Journal of Electronic Science and Technology     Open Access   (Followers: 1)
Journal of Electronics (China)     Hybrid Journal   (Followers: 5)
Journal of Energy Storage     Full-text available via subscription   (Followers: 4)
Journal of Engineered Fibers and Fabrics     Open Access   (Followers: 2)
Journal of Field Robotics     Hybrid Journal   (Followers: 3)
Journal of Guidance, Control, and Dynamics     Hybrid Journal   (Followers: 182)
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: 10)
Journal of Low Power Electronics and Applications     Open Access   (Followers: 10)
Journal of Microelectronics and Electronic Packaging     Hybrid Journal   (Followers: 1)
Journal of Microwave Power and Electromagnetic Energy     Hybrid Journal   (Followers: 3)
Journal of Microwaves, Optoelectronics and Electromagnetic Applications     Open Access   (Followers: 11)
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: 31)
Journal of Power Electronics     Hybrid Journal   (Followers: 1)
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 ELTIKOM : Jurnal Teknik Elektro, Teknologi Informasi dan Komputer     Open Access  
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  
Majalah Ilmiah Teknologi Elektro : Journal of Electrical Technology     Open Access   (Followers: 2)
Metrology and Measurement Systems     Open Access   (Followers: 6)
Microelectronics and Solid State Electronics     Open Access   (Followers: 28)
Nanotechnology, Science and Applications     Open Access   (Followers: 6)
Nature Electronics     Hybrid Journal   (Followers: 1)
Networks: an International Journal     Hybrid Journal   (Followers: 5)
Open Electrical & Electronic Engineering Journal     Open Access  
Open Journal of Antennas and Propagation     Open Access   (Followers: 9)
Paladyn. Journal of Behavioral Robotics     Open Access   (Followers: 1)
Power Electronics and Drives     Open Access   (Followers: 2)
Problemy Peredachi Informatsii     Full-text available via subscription  
Progress in Quantum Electronics     Full-text available via subscription   (Followers: 7)
Radiophysics and Quantum Electronics     Hybrid Journal   (Followers: 2)
Recent Advances in Communications and Networking Technology     Hybrid Journal   (Followers: 4)
Recent Advances in Electrical & Electronic Engineering     Hybrid Journal   (Followers: 11)
Research & Reviews : Journal of Embedded System & Applications     Full-text available via subscription   (Followers: 6)
Revue Méditerranéenne des Télécommunications     Open Access  
Security and Communication Networks     Hybrid Journal   (Followers: 2)
Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of     Hybrid Journal   (Followers: 56)
Semiconductors and Semimetals     Full-text available via subscription   (Followers: 1)
Sensing and Imaging : An International Journal     Hybrid Journal   (Followers: 2)
Solid State Electronics Letters     Open Access  
Solid-State Electronics     Hybrid Journal   (Followers: 9)
Superconductor Science and Technology     Hybrid Journal   (Followers: 3)
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)
Transactions on Electrical and Electronic Materials     Hybrid Journal   (Followers: 1)
Universal Journal of Electrical and Electronic Engineering     Open Access   (Followers: 7)
Ural Radio Engineering Journal     Open Access   (Followers: 1)
Visión Electrónica : algo más que un estado sólido     Open Access   (Followers: 1)
Wireless and Mobile Technologies     Open Access   (Followers: 6)

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Similar Journals
Journal Cover
IEEE Transactions on Power Electronics
Journal Prestige (SJR): 2.215
Citation Impact (citeScore): 9
Number of Followers: 79  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0885-8993
Published by IEEE Homepage  [228 journals]
  • IEEE Power Electronics Society
    • Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • IEEE Power Electronics Society
    • Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Administrative Committee
    • Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Decoupling Circuit for Automated Guided Vehicles IPT Charging Systems With
           Dual Receivers
    • Authors: Ruikun Mai;Ying Luo;Bin Yang;Yi Song;Shunpan Liu;Zhengyou He;
      Pages: 6652 - 6657
      Abstract: It is more efficient to employ inductive power transfer (IPT) systems to charge automated guided vehicles (AGVs) than traditional plug-in systems. In order to provide independent and different charging power for the driven system and the control system of AGVs simultaneously, this letter proposes a coaxial dual-receiver structure and a decoupling circuit, which utilizes a passive component connected with two receiving coils to cancel out the mutual inductance between each other. By using this decoupling method, the two receiving coils could be treated as independent receivers without precise placement or additional transformers. First, the decoupling model is analyzed in detail, and the value of the decoupling component is given without any restriction of the ratio of their current. Then, the structure of the dual receiver is designed. Finally, an IPT system with one transmitter and dual receivers is built to verify the feasibility of the proposed method. Experimental results show that when one of the loads varies from 20 to 80 Ω, the voltage fluctuation of the other load is as small as 1.36% with decoupling, whereas 54.46% of voltage fluctuation without decoupling. The results validate that the proposed method is suitable for the application requiring dual independent outputs in the same equipment.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Optimal Reference Frame Angle Approach for Air-Gap Flux Minimization in
           Dual Stator Winding Induction Machines
    • Authors: Mojtaba Ayaz Khoshhava;Hossein Abootorabi Zarchi;Gholam Reza Arab Markadeh;
      Pages: 6658 - 6662
      Abstract: Dual stator winding induction machines (DSWIMs), which have two sets of three-phase windings with unequal pole pairs in their stator and a standard squirrel cage rotor, have overcame the narrow speed operation region and circulating current problems exists in other types of dual winding machines. These advantages are resulted from the independent operation of their winding sets. The independent operation of winding sets will be guaranteed if the flux saturation is avoided. This letter proposes a novel reference frame angle determination technique that not only guarantees the flux saturation avoidance but also results in flux optimization in DSWIMs. Despite pervious methods, the proposed method does not require position or speed sensor and it is easily applicable in various control schemes and in different reference frames. This method is implemented in a flux and torque vector control system for driving a 3.3 kW DSWIM. The experimental results confirm the effectiveness of the proposed method. Moreover, by implementing the proposed method, the torque sharing between the two winding sets is properly done according to the power rating of each of them.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • New Insights on Output Capacitance Losses in Wide-Band-Gap Transistors
    • Authors: Mohammad Samizadeh Nikoo;Armin Jafari;Nirmana Perera;Elison Matioli;
      Pages: 6663 - 6667
      Abstract: The low on-resistance of wide-band-gap (WBG) transistors is a key feature for efficient power converters; however, the anomalous loss in their output capacitance (COSS) severely limits their performance at high switching frequencies. Characterizing COSS losses based on the large-signal measurement methods requires an extensive effort, as separate measurements are needed at different operation points, including voltage swing, frequency, and dv/dt. Furthermore, there is a practical tradeoff in the maximum voltage and frequency applied to the device. Here, we introduce a new circuit model, including an effective COSS and a frequency-dependent series resistance, along with a simple small-signal method to fully characterize COSS losses in WBG transistors. The method accurately predicts COSS losses at any voltage swing or frequency. Contrary to other methods, this technique directly leads to a general identification of COSS losses at different operation points, revealing new insights on COSS losses in WBG transistors, especially the dependence of EDISS on voltage and frequency. Based on the proposed approach, the issue of COSS losses in enhancement-mode GaN and SiC transistors was assigned to the limited quality factor of COSS. The precise characterization of COSS losses proposed in this letter is essential for designing efficient high-frequency power converters.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Dynamic Model of the DC Fault Clearing Process of a Hybrid Modular
           Multilevel Converter Considering Commutations of the Fault Current
    • Authors: Shukai Xu;Qiang Song;Yuebin Zhou;Jingwei Meng;Wenbo Yang;Biao Zhao;Rong Zeng;
      Pages: 6668 - 6672
      Abstract: Hybrid modular multilevel converter that consists of a combination of half-bridge submodules and full-bridge submodules (FBSMs) can block dc fault current. However, in the case of distant bulk power transmission, the large excess energy that stored in the long-distance line will greatly affect the fault clearing time and FBSM capacitor overvoltage. During the fault clearing process, several commutations of the fault current from one arm to another may occur during the fault clearing process. A dynamic model, in which the commutations of the fault current are considered, is proposed to describe the fault clearing process after converter blocking in precise detail. The fault clearing time and FBSM overvoltage can be exactly estimated. The analytical analysis model is verified by the simulation and experimental results.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Enhanced DAB for Efficiency Preservation Using Adjustable-Tap
           High-Frequency Transformer
    • Authors: Armin Jafari;Mohammad Samizadeh Nikoo;Furkan Karakaya;Elison Matioli;
      Pages: 6673 - 6677
      Abstract: Efficient dc–dc power-conversion with wide-span voltage-regulation is crucial to a sustainable and robust power electronics system. Dual-active-bridge (DAB) offers straight-forward regulation and its transformer enables voltage step-up/down required for many applications, such as battery chargers and bus converters for dc distribution systems. However, losing soft-switching at light loads or when operating at voltage gains far from the turns ratio severely degrades the efficiency of DAB, especially at high switching frequencies. In this article, we demonstrate an enhanced DAB (E-DAB) topology which employs an adjustable-tap transformer to extend the soft-switching over wider voltage gains and increase the power-transfer capability. By a proper tap adjustment and with single phase-shift modulation, the proposed gallium nitride (GaN)-based converter achieved a peak efficiency of 97.4% with an overall efficiency greater than a conventional DAB for voltage gains of up to 2.8 times higher. Employing a quasi-planar matrix transformer with integrated leakage inductance at 300 kHz allowed for an extremely high power density of 10 kW/l (7.5 kW/l with cooling). The tapped transformer did not incur extra losses to the topology. The gain versus power-transfer characteristic for soft-switching operation was derived for the E-DAB and its improvement in efficiency was experimentally verified over a wide power range.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Online Capacitance Estimation of Submodule Capacitors for Modular
           Multilevel Converter With Nearest Level Modulation
    • Authors: Kun Wang;Lin Jin;Guangdi Li;Yan Deng;Xiangning He;
      Pages: 6678 - 6681
      Abstract: This letter proposes an online capacitance estimation method for the modular multilevel converter. In the prevalent methods, the inherent second-order circulating current or the injected low-frequency current/voltage component is utilized to calculate the submodule (SM) capacitance. In this letter, the relationship between the voltage variation of an SM capacitor in one fundamental period and the driving signals switching angle under the nearest level modulation scheme is revealed. The voltage variation of each SM capacitor is a direct component and has no relationship with the second-order harmonic current and voltage ripples. Accordingly, an online capacitance estimation method for HVdc applications is proposed by simply monitoring the SM capacitor voltage variations at fundamental frequency. In the proposed scheme, neither the current/voltage injection nor the inherent circulating current is required, which reduces the estimation complexity. The recursive least squares algorithm is also adopted to guarantee the accuracy of the estimation method. Effectiveness of the proposed online capacitor estimation method is verified by the experimental results.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A Fast Positive Sequence Components Extraction Method With Noise Immunity
           in Unbalanced Grids
    • Authors: Liwei Du;Mingxian Li;Zhen Tang;Liansong Xiong;Xun Ma;Guoxin Tang;
      Pages: 6682 - 6685
      Abstract: Fast and accurate acquisition of voltage components is the basic requirement for grid-tied inverters to realize various control under unbalanced grids. In view of this situation, a delay sampling period filter, which rapidly separates each voltage component by delaying two sampling periods in dq frame, is proposed in this article. In view of the noise interference, a delay operation period filter (DOPF) is proposed to scale the operation period and limit the noise to an acceptable range. The complete positive sequence components (PSC) extraction method based on the developed DOPF+ moving average filter (MAF) algorithm is presented, combing the advantages of DOPF and MAF for eliminating the double-frequency ac components and high-frequency noise, respectively. Finally, the feasibility and priority of the DOPF+MAF algorithm and PSC extraction method have been verified by the physical experimental results.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A Synchronization Method for the Modular Series-Connected Inverters
    • Authors: Peng Liu;Lei Song;Shanxu Duan;
      Pages: 6686 - 6690
      Abstract: The series-connected system is widely used in the medium or high voltage applications. For the series-connected inverter system, the phase angle synchronization should be guaranteed to ensure the total output voltage. Usually, a centralized controller is used to send the same voltage command to each module downstream. In order to improve the flexibility and scalability of the modular system, a decentralized synchronization method is proposed in this letter. The synchronization principle, control strategy, and control parameter design guidance are introduced step by step. Finally, the performance of the proposed strategy is verified by a series-connected three-module inverters system.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A Reference Submodule Based Capacitor Condition Monitoring Method for
           Modular Multilevel Converters
    • Authors: Zhongxu Wang;Yi Zhang;Huai Wang;Frede Blaabjerg;
      Pages: 6691 - 6696
      Abstract: This letter proposes a novel capacitor condition monitoring method for modular multilevel converters (MMCs) based on reference submodules (SMs). It significantly enhances the capacitor monitoring accuracy by making full use of the SM voltage sensor measurement range. Accuracy comparison between the existing method and the proposed method is conducted to quantify the improvement of accuracy. Moreover, its operation principle and practical implementation considerations are presented. Finally, a three-phase MMC platform is built to experimentally verify the effectiveness of the proposed method.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Effects of Number of Relays on Achievable Efficiency of Magnetic Resonant
           Wireless Power Transfer
    • Authors: Junseob Lee;Kisong Lee;
      Pages: 6697 - 6700
      Abstract: In magnetic resonant wireless power transfer (WPT), relays are placed between a transmitter and a receiver as a means of increasing both the operating distance and the power transfer efficiency, but this makes the analysis of the WPT system more complicated. In this letter, we derive a mathematical expression for the power transfer efficiency with an optimal load resistance based on an equivalent circuit model, and analyze the effects of varying the number of relays on the power transfer efficiency that can be achieved. By means of circuit-level simulations and experiments under a variety of scenarios, we verify the accuracy of our analysis, and we also confirm that there is an optimal number of relays for maximizing the achievable power transfer efficiency for a given end-to-end distance.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Converter-Based Power System Protection Against DC in Transmission and
           Distribution Networks
    • Authors: Moazzam Nazir;Klaehn Burkes;Johan H. R. Enslin;
      Pages: 6701 - 6704
      Abstract: The dc in a power system may be caused by geomagnetic disturbances that are the result of solar storms and high-altitude nuclear detonations. Increased inverter-based generation is also contributing to small dc injection into the power systems. The resultant dc could have serious consequences for the power systems as it may drive power transformers into saturation, cause transformer internal heating, cause large draw of reactive power, and misoperation of protective relays. This letter proposes a novel power electronics-based dc mitigation approach that involves a transformerless series active filter integrated between the neutral point and ground of power transformers serving multiple purposes. The first objective is to surpass the effect of dc injection, the second goal is voltage regulation, and the third is to provide harmonic isolation or impedance balancing. The proposed device is currently being developed on a 7.2-kV/240-V single-phase transformer; however, the solution is also relevant for 24–500-kV networks. The system circuitry, operation, and control are implemented and verified for this letter in a controller hardware-in-the-loop (C-HIL) test setup using a Typhoon HIL-402 simulator. Results indicate that our approach is a promising alternative to traditional neutral capacitor-blocking strategies.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A Compact Rectenna Design With Wide Input Power Range for Wireless Power
           Transfer
    • Authors: Ping Lu;Chaoyun Song;Ka Ma Huang;
      Pages: 6705 - 6710
      Abstract: A compact rectenna with a wide input power range is proposed for wireless power transfer (WPT). Two different diodes, having distinct operating powers, i.e., high-input-power diode and low-input-power diode, are introduced to the rectenna design for extending the operating input power range. A mid-inductor is placed in the rectifying circuit to isolate the radio frequency (RF) signal from dc power, thereby delivering the rectified dc power to the load. Also, with the aid of mid-inductor, the fundamental RF signal and harmonic signals could flow back to the two rectifying diodes for achieving higher conversion efficiency via the means of harmonic signal re-rectification. Owing to the mid-inductor, the sub-rectifier circuit can be avoided, and a compact structure can therefore be realized. Over 50% measured conversion efficiency, ηc can be achieved in a very wide input power range of 35 dB (−10 to 25 dBm). The proposed rectenna can be widely used in WPT systems with unpredictable and variable RF energy levels.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • How Can a Cutting-Edge Gallium Nitride High-Electron-Mobility Transistor
           Encounter Catastrophic Failure Within the Acceptable Temperature Range?
    • Authors: Sungyoung Song;Stig Munk-Nielsen;Christian Uhrenfeldt;
      Pages: 6711 - 6718
      Abstract: Commercial gallium nitride (GaN) high-electron-mobility transistors used for power electronics applications show superior performance compared to silicon (Si)-based transistors. Combined with an increased radiation hardening properties, they are key candidates for high-performance power systems in a harsh environment, such as space. However, for this purpose, it is key to know the potential failure mechanisms (FMs) of the devices in depth. Here, we demonstrate how the repeated thermomechanical stress in a power cycling (PC) test within specified operating conditions destroys the GaN device. Based on leakage current localization analysis, we identify an FM with a yet unknown root cause. Utilizing emission microscopy, focused ion beam cutting, and scanning electron microscope techniques, it is revealed that multilayer cracks of a GaN die are triggered by a commercial leading package structure, which shows excellent capability under frequent thermomechanical stress. Through multiphysics simulations, it is shown that the structural factors that lie behind the strong performing component properties inside the package ultimately are directly related to the failure pattern. This article is accompanied by a video demonstrating dynamic thermal distribution difference between thermography measured in a practical experiment and a multiphysics simulation result during a single PC of a PC test. This article is accompanied by a supplementary figures file demonstrating test environment, preparation process of specimens, and reverse engineering results for the simulation model.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Predictive Direct Control of SPMS Generators Applied to the Machine Side
           Converter of an OWC Power Plant
    • Authors: Mohammad Ebrahim Zarei;Dionisio Ramirez;Carlos Veganzones;Jaime Rodriguez;
      Pages: 6719 - 6731
      Abstract: A new strategy framed in the field of model predictive direct current control applied to surface permanent magnet synchronous generator (SPMSG) is presented. Compared to conventional space vector control systems, the proposed predictive strategy reduces the number of PI regulators and maintains the advantages of a fixed switching frequency. It also performs a faster response providing a smooth electromagnetic torque and smooth active and reactive power control. The dynamic performance of the proposed control is first analyzed by means of simulations in MATLAB Simulink environment and then compared with two other model predictive controls. Also, the performance of the control is analyzed in simulation using a simple model of an oscillating water column power plant. This application was chosen because it is a difficult case study that demands a fast torque control to handle the power take-off system. Later, the proposed method is tested in a customized SPMSG-based laboratory setup. This article is accompanied by a video.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A Dynamic WPT System With High Efficiency and High Power Factor for
           Electric Vehicles
    • Authors: Ali Zakerian;Sadegh Vaez-Zadeh;Amir Babaki;
      Pages: 6732 - 6740
      Abstract: Dynamic wireless power transfer (WPT) for charging electric vehicles (EVs) overcomes some of the problems associated with EVs battery size and weight as well as distance range limitation and long charging duration. High efficiency and fixed output voltage of WPT systems are of great importance for reducing operating cost and facilitating battery charging, respectively. On the other hand, utilizing the maximum power transfer capability of a WPT system leads to a capital cost saving of the system. In this article, the product of transferred power efficiency and input power factor (η·PF) is regarded as a criterion to make near full usage of the system power transfer capacity as well as reduce the capital and operating cost of the system. An optimal frequency-tracking method is proposed to maximize η·PF of the system taking into account possible abrupt changes in the coupling coefficient of the WPT system due to deviations of EV from alignment with the track along the road. In addition, the output voltage of the system is regulated simultaneously by an on-line adjustment of the primary inverter duty ratio. The optimal frequency-tracking method and voltage regulation are validated by extensive simulation and experimental results.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A New Coupling Structure and Position Detection Method for Segmented
           Control Dynamic Wireless Power Transfer Systems
    • Authors: Xiaofei Li;Jiefeng Hu;Heshou Wang;Xin Dai;Yue Sun;
      Pages: 6741 - 6745
      Abstract: In this letter, a new coupling structure for dynamic wireless power transfer (DWPT) systems is proposed. Bipolar coils are symmetrically placed on the transmitter unipolar coils, resulting in natural decoupling between the bipolar coils and the unipolar coils. This special structure can mitigate the self-couplings between the adjacent unipolar transmitter coils and hence facilitate the design of the compensation circuit. Another remarkable advantage of this design is that it can lead to a stable mutual coupling between the transmitter array and the receiver when the receiver moves along the transmitter, making it a natural fit for DWPT applications. Furthermore, to reduce the electromagnetic interference and power loss, an automatic segmented control scheme is implemented, and a position detection method by monitoring the primary current is developed. The feasibility of the proposed coupling structure and the position detection method are verified on a laboratory prototype with 72-V output voltage. The experimental results show that the power fluctuation is within ±2.5%, and system efficiency is around 90%. (This letter is accompanied by a video demonstrating the experimental test).
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A Cost-Constrained Active Capacitor for a Single-Phase Inverter
    • Authors: Haoran Wang;Huai Wang;Frede Blaabjerg;
      Pages: 6746 - 6760
      Abstract: The active capacitor concept based on power electronic circuits has been proposed recently to exceed the physical limit of the passive capacitor. It retains the physical convenience of use as a passive capacitor and has the potential to increase either the power density or the lifetime depending on the applications. However, the cost of the existing design by using ceramic or film capacitors to achieve extreme performance increases a lot, which must be taken into account in the design from the industry aspect. This article proposes a cost-constrained design of an active capacitor used for dc-link applications. It is implemented based on high-current electrolytic capacitors instead of film capacitors or ceramic capacitors. A model-based optimization design procedure is discussed in terms of performance factors of interest. A case study of a 5.5-kW single-phase inverter demonstrates a 38% volume reduction of the dc link with the proposed active capacitor under specific constraints of cost, volume, power loss, and lifetime. The outcomes move one step further for the practical application of the active capacitor concept.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Bond Wire Damage Detection and SOH Estimation of a Dual-Pack IGBT Power
           Module Using Active Power Cycling and Reflectometry
    • Authors: Abu Hanif;Douglas DeVoto;Faisal Khan;
      Pages: 6761 - 6772
      Abstract: High thermal and electrical stress, over a period of time tends to deteriorate the health of power electronic switches. Being a key element in any high-power converter systems, power switches, such as insulated-gate bipolar junction transistors (IGBTs) and metal-oxide semiconductor field-effect transistors, are constantly monitored to predict when and how they might fail. A huge fraction of research efforts involves the study of power electronic device reliability and development of novel techniques with higher accuracy in the health estimation of such devices. Until today, no other existing technique can determine the number of lifted bond wires and their locations in a live IGBT module, although this information is extremely helpful to understand the overall state-of-health of an IGBT power module. Through this article, a new method for online condition monitoring of IGBTs and IGBT modules using spread spectrum time-domain reflectometry has been proposed. Unlike traditional methods, this research work concentrates at the gate terminals (low voltage) of the device instead of looking at the collector side. In addition, the RL-equivalent circuit to represent a bond wire has been developed for the device under test and simulated in CST Studio Suite to measure the reflection amplitudes. Experimental results were obtained using a prototype reflectometry hardware, and both the simulation and experimental results have been compared. These results prove that a single measurement is sufficient to predict the failure of the device instead of looking at the traditional precursor parameter (VCEON). With only two sets of measurements, it is possible to locate the aged device inside a module and detect the number of bond wire liftoffs associated with that device.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Cost-Effective Prognostics of IGBT Bond Wires With Consideration of
           Temperature Swing
    • Authors: Keting Hu;Zhigang Liu;He Du;Lorenzo Ceccarelli;Francesco Iannuzzo;Frede Blaabjerg;Ibrahim Adamu Tasiu;
      Pages: 6773 - 6784
      Abstract: This article presents a cost-effective prognostic method for the bond wires in the insulated-gate bipolar transistor (IGBT). Consider that the crack propagation in the wire bond leads to the bond wire liftoff, the corresponding state equation is established from the fracture mechanics theory, with the consideration of the uneven distribution of the temperature swings. Hence, the proposed model can work under different loading conditions. With the fact that the on-state voltage $(v_{{rm{ce,on}}})$ of the IGBT shifts with the crack propagation, the history $v_{{rm{ce,on}}}$ is used to predict the remaining useful lifetime (RUL), through which numerous power cycling tests are avoided, and low economical cost for doing prognosis is fulfilled. In this article, the functional relationship between the increase of $v_{{rm{ce,on}}}$ and the crack length of each bond wire is obtained through finite-element simulation, while the effects of the temperature variation and metallization degradation to the $v_{{rm{ce,on}}}$ are compensated. Thus, the output equation can be obtained. Then, the unknown parameters of the aforementioned equations and the current crack length can be estimated by the particle-based marginalized resample-move algorithm. Finally, the RUL can be predicted effectively by evolving the particles obtained in the algorithm. The proposed method has been validated by the power cycling test.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Strategy of Topology Selection Based on Quasi-Duality Between
           Series–Series and Series–Parallel Topologies of Resonant Inductive
           Coupling Wireless Power Transfer Systems
    • Authors: Masataka Ishihara;Kazuhiro Umetani;Eiji Hiraki;
      Pages: 6785 - 6798
      Abstract: Series–series (SS) and series–parallel (SP) topologies are widely used in resonant inductive coupling wireless power transfer systems for various applications. However, the selection of an appropriate topology to achieve higher output power or higher efficiency is typically difficult because design optimization of the circuit parameters (e.g., characteristic impedance, load resistance, and mutual inductance) for each topology is generally separately discussed using different equivalent circuits with multiple resonance modes. Therefore, the purpose of this study involves proposing a simple strategy to select an appropriate topology. The proposed strategy is based on quasi-duality between the SS and SP topologies that are elucidated from the novel equivalent circuits derived using Lagrangian dynamics. Based on the quasi-duality, the output power and efficiency of the SP topology are calculated via the equivalent circuit of SS topology. Thus, the quasi-duality offers a simple comparison between the SS and SP topologies. The proposed strategy selects an appropriate topology by comparing only the equivalent ac load resistance, which is the ac resistance including the rectifying circuit and the load resistance, the characteristic impedance, and the ac load resistance that achieves the maximum efficiency or maximum output power of the SS topology. Experiments verify the appropriateness and effectiveness of the proposed strategy.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Feasibility Study of Nanocrystalline-Ribbon Cores for Polarized Inductive
           Power Transfer Pads
    • Authors: Daniel E. Gaona;Saikat Ghosh;Teng Long;
      Pages: 6799 - 6809
      Abstract: MnZn-based ferrite materials like the EPCOS N87 or K2004 are commonly used as magnetic cores in inductive power transfer (IPT) applications. However, the performance and the reliability of IPT systems are limited by ferrite's intrinsic brittleness and low flux density saturation point. In this article, a study of nanocrystalline-ribbon-based magnetic cores for IPT applications is presented. Finite element method (FEM) simulations and experimental validations are used to compare both materials. The design of ultrathin laminated cores such as nanocrystalline ribbons for IPT systems is presented. Compared to ferrite, nanocrystalline ribbon is mechanically more robust; it has a higher magnetic permeability and a higher saturation point. Results show that nanocrystalline ribbon cores achieve more than a $text{50}%$ volume reduction when used in IPT pads. This is due to nanocrystalline's high saturation point. However, a compromise arises as the total power loss increases due to the induced eddy currents in the core. The reduction of efficiency can be mitigated by special geometrical designs of the nanocrystalline ribbon cores. A 6.6-kW IPT system has been built for experimental validation of the design methodology.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • An Improved Pulse Density Modulation Strategy Based on Harmonics for ICPT
           System
    • Authors: Xuerui Sheng;Liming Shi;
      Pages: 6810 - 6819
      Abstract: To improve the efficiency of high frequency inverter (HFI) in inductively coupled power transfer system, pulse density modulation (PDM) is often used. However, the output current of the HFI fluctuates seriously, especially at light load. It affects the stable operation of the system and the implementation of zero voltage switching. In this article, an improved pulse density modulation (IPDM) is proposed to reduce current fluctuation. It applies harmonics pulse to replace the fundamental pulse and zero state, and evenly distributes the switching sequence to reduce current fluctuation. Simultaneously, the best phase-shift angle of harmonics is obtained by using the transient analysis method to further reduce the output current fluctuation. The IPDM current fluctuation is less than PDM and the efficiency become higher at light load by the theoretical analysis, while PDM is better at heavy load. So, a hybrid modulation strategy is applied that IPDM and PDM are used for light and heavy load, respectively. The experimental results show that the HFI output current ripple coefficient is reduced by 15% to 62% and the efficiency is improved at light load.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Single-Stage Regulated Resonant WPT Receiver With Low Input Harmonic
           Distortion
    • Authors: Kerui Li;Siew Chong Tan;Ron Shu Yuen Hui;
      Pages: 6820 - 6829
      Abstract: Resonant rectifier topologies would be a promising candidate for achieving simple, compact, and reliable single-stage wireless power transfer (WPT) receiver if not for the lack of good dc regulation capability. This article investigates the problems that prevent the feasibility of single-stage dc regulation in resonant rectifier topologies. A possible solution is the proposed differential resonant rectifier topology, of which the rectifier is designed to have a relatively constant ac voltage, and that phase-shift control is used to achieve relatively good output regulation. Design considerations on the reactive component sizing, magnetic component design, frequency and phase synchronization, small-signal modeling, and closed-loop feedback control design, are discussed. Experimental results verified that the proposed WPT receiver system can achieve single-stage ac rectification and dc regulation while attaining the key features of low harmonic distortion in its ac output voltage, continuous dc current, and zero-voltage-switching operation over a wide operating range.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Analytical Factorized Model for Stability Analysis and Optimization of
           Shunt RC Damped LCL Filter for Grid-Connected Voltage Source Inverters
    • Authors: Ahmed Koran;Saher Albatran;Jih-Sheng Lai;
      Pages: 6830 - 6841
      Abstract: In this article, an optimal design procedure of shunt RC damped LCL filter is discussed. The proposed design procedure finds the minimum damping resistance to guarantee the stability of the grid-current controller without affecting the effectiveness of the filter. This minimum value is derived using the factorized filter input admittance and filter forward transadmittance. The proposed factorization procedure allows us to have an analytical expression of system poles and zeros. Moreover, the minimum damping resistor is determined upon the desired crossover frequency and the desired phase margin of the grid-current controller. After that, an objective function is assumed, and an optimization problem is formulated to minimize the physical size of the filter by minimizing the total capacitance and inductance and by minimizing the filter ripple content as well. Accordingly, the proposed objective function minimizes the filter physical size and filter power losses and, hence, enhances filter's efficiency. A prototype demonstrates and validates the proposed filter design and analysis experimentally.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Improved Current Control for a Quasi-Two-Level PWM-Operated Modular
           Multilevel Converter
    • Authors: Jakub Kucka;Axel Mertens;
      Pages: 6842 - 6853
      Abstract: Quasi-Two-Level PWM Operation of modular multilevel converters enables a significantly smaller amount of installed module capacitance, even with low output frequencies required for machine drives. This article presents an implementation of this operation mode with an improved current control that leads to fast and precise current transitions. The proposed current control combines a deadbeat controller with a simple hysteresis controller that uses a predictive estimation of branch currents, which are both implemented using an FPGA. The enhanced performance of the proposed control is demonstrated by a comparison to the original one. Experimental results on a laboratory prototype prove the feasibility of Quasi-Two-Level PWM Operation as a machine drive and validate the advantage of reduced overvoltages with long machine cables in comparison to those of conventional two-level inverters.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Design of Compact Three-Phase Receiver for Meander-Type Dynamic Wireless
           Power Transfer System
    • Authors: Chao Wang;Chunbo Zhu;Guo Wei;Jing Feng;Jinhai Jiang;Rengui Lu;
      Pages: 6854 - 6866
      Abstract: Three-phase meander-type dynamic wireless power transfer is ideal for the power supply or charging of rail vehicles. However, there is a lack of systematic analysis and design of the three-phase receiver. To achieve the compact design of the three-phase receiver in practical applications, this article studies the compact three-phase receiver with overlapped receiving coils and ferrite core. Based on the analysis of the fundamental coupling characteristic of three-phase meander-type dynamic wireless power transfer, two overlap modes of the receiving coils are concluded and compared. Meanwhile, by considering the influence of mutual inductance harmonic distortion, the accuracy of the receiving coil analysis and design is improved. Furthermore, a practical distributed strip core design is presented to enhance the coupling between transmitting coils and receiving coils. Additionally, the effect of the core on coupling imbalance is analyzed in detail and proves to have little effect on the power transfer. Afterward, a design flow of star-connected series-compensated receiver with the overlapped coils and the distributed strip core is proposed. Finally, for verification, a small prototype with an average output power of 154 W and average efficiency of 97% of the receiving coils is established.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A Family of Hybrid IPT Topologies With Near Load-Independent Output and
           High Tolerance to Pad Misalignment
    • Authors: Xiaohui Qu;Yunchang Yao;Dule Wang;Siu-Chung Wong;Chi K. Tse;
      Pages: 6867 - 6877
      Abstract: Inductive power transfer (IPT) systems have many unique benefits compared to conventional plugged-in systems. The coupling pads in IPT systems are inevitably misaligned in many practical applications, thus leading to variations of the transferred power and efficiency that necessitate the use of complicated control for output regulation. A common solution is to use two IPT converters with opposite trends of output to pad misalignment, so that the total output voltage or current could be kept near constant for large coupling variations. However, methods for deriving effective configurations for such hybrid IPT converters and their achievable tolerance to the misalignment are still missing. This article constructs a family of hybrid IPT topologies, including input-parallel–output-parallel, input-parallel–output-series, input-series–output-parallel (ISOP), and input-series–output-series for delivering a constant current (CC) or a constant voltage (CV). Design principles and characteristics for all the hybrid systems with near load-independent output and high tolerance to pad misalignment are derived and discussed in detail. Based on this family of configurations, this article also combines some existing IPT topologies and derives multiple hybrid converters for CC or CV output by using a simple duty cycle control. Finally, a 3.5-kW hybrid IPT prototype converter based on the ISOP structure is built to verify the theoretical analysis.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Deadbeat Predictive Current Control for Modular Multilevel Converters With
           Enhanced Steady-State Performance and Stability
    • Authors: Jinyu Wang;Yi Tang;Pengfeng Lin;Xiong Liu;Josep Pou;
      Pages: 6878 - 6894
      Abstract: Model predictive control (MPC) methods are popularly employed in modular multilevel converters (MMCs) due to their fast dynamic response and multiobjective control capability. However, they present some inherent problems, such as computational complexity, variable switching frequency, poor steady-state performance, and tedious weighting factor selection. This article develops a deadbeat predictive current control method for MMCs. This method can realize the reference tracking of ac current and circulating current in one sampling period without error, and thus provide a fast dynamic response as conventional MPC methods. Besides, switching state or voltage level evaluation, cost function calculation as well as weighting factor selection are not required. Therefore, it has a very low calculation burden, which is independent of the number of submodules (SMs). Since a modulation stage is utilized, a fixed switching frequency and consequently a satisfactory steady-state performance are obtained. The effects of time delay, parameter mismatch, and SM capacitor voltage ripple on the control algorithm are discussed. Also, the corresponding improvement measures are provided to further enhance the steady-state performance and system stability of MMCs. The effectiveness and performance of the developed control algorithm are verified by experimental results.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Asymmetrical Bidirectional DC–DC Converter With Limited Reverse Power
           Rating in Smart Transformer
    • Authors: Rongwu Zhu;Felix Hoffmann;Nimrod Vázquez;Kangan Wang;Marco Liserre;
      Pages: 6895 - 6905
      Abstract: The increasing penetration of distributed generators in low-voltage distribution grids may lead to distribution transformers, also a smart transformer, experiencing the reverse power flow, which is less as compared to the forward power flow in the current electric grid. This article proposes an asymmetrical bidirectional dc–dc (AB-DC/DC) converter, which has two partial-scale rectifiers of an active bridge and a diode bridge connected in parallel at the secondary side, with less cost of power semiconductors and the capability of bidirectional operation to satisfy the realistic condition. The proposed AB-DC/DC converter works as a single active bridge under forward power flow condition, while it works as a dual active bridge under reverse power flow condition. The solutions to share the active power under forward operation and suppress the circulating power under reverse operation are proposed, respectively. The simulation and experimental results both clearly validate the effectiveness and feasibility of the proposed AB-DC/DC converter.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Asymmetrical Triangular Current Mode (ATCM) for Bidirectional High Step
           Ratio Modular Multilevel Dc–Dc Converter
    • Authors: Cristian Pineda;Javier Pereda;Felix Rojas;Carlos Cerda;Xiaotian Zhang;Alan J. Watson;
      Pages: 6906 - 6915
      Abstract: Direct current (Dc) networks have proven advantages in high voltage direct current (HVDC) transmission systems, and now they are expanding to medium- and low-voltage distribution networks. One of the major challenges is to develop reliable dc–dc voltage transformation achieving high efficiency and performance, especially at high voltage and high step ratio. New resonant modular multilevel topologies have arisen as an alternative, mainly because of advantages such as optional use of transformers, natural voltage balance, simple control, and soft-switching capability. However, this type of operation generates a high peak current, does not allow control of power flow in all power range, and has a limited range of voltage variation. This article proposes an asymmetrical triangular current mode applied to high step ratio modular multilevel dc–dc converters. The proposed modulation increases the efficiency and achieves bidirectional control of the power, soft-switching, and a natural balance of the voltage in the cell capacitors. The experimental results show the bidirectional operation and the capacitor voltage balance of the converter under different operating conditions with higher efficiency (97.72%) and lower peak current compared to previous reports of this topology using resonant operation.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Mission Profile-Based System-Level Reliability Prediction Method for
           Modular Multilevel Converters
    • Authors: Yi Zhang;Huai Wang;Zhongxu Wang;Frede Blaabjerg;Maryam Saeedifard;
      Pages: 6916 - 6930
      Abstract: This article proposes a mission profile-based reliability prediction method for modular multilevel converters (MMCs). It includes key modeling steps, such as long-term mission profile, analytical power loss models, system-level and component-level thermal modeling, lifetime modeling, Monte Carlo analysis, and redundancy analysis. Thermal couplings and uneven thermal stresses among submodules are considered. A case study of a 15-kVA down-scale MMC has been used to demonstrate the proposed method and validate the theoretical analysis. The outcomes serve as a first step for developing realistic reliability analysis and model-based design methods for full-scale MMCs in practical applications.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Line Current Ripple Minimization PWM Strategy With Reduced Zero-Sequence
           Circulating Current for Two Parallel Interleaved Three-Phase Converters
    • Authors: Zhiyong Zeng;Zhongxi Li;Stefan M. Goetz;
      Pages: 6931 - 6943
      Abstract: This article proposes a line-current ripple minimization pulsewidth modulation strategy with reduced zero-sequence circulating current (ZSCC) for two parallel three-phase two-level converters. We split each 60° sector into six subsectors, each applies the nearest three vectors to ensure minimal line-current ripple. To reduce the ZSCC, we further investigate all vector sequences of the nearest three vectors and derive an optimal vector sequence for each of the six subsectors. We unify all carrier sequences under a carrier-based modulation scheme with the assistance of voltage injections. The injected voltage can be computed by a simple algorithm that allows easy implementation in mainstream microcontrollers. The experimental results validate that the proposed method maintains the minimal line-current ripple while significantly reducing the ZSCC compared to the existing line current ripple minimization methods.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A Reduced Common-Mode-Voltage Pulsewidth Modulation Method With Output
           Harmonic Distortion Minimization for Three-Level Neutral-Point-Clamped
           Inverters
    • Authors: Khoa Dang Pham;Nho Van Nguyen;
      Pages: 6944 - 6962
      Abstract: This article presents a carrier-based pulsewidth modulation (PWM) strategy to reduce the common-mode voltage (CMV) with output harmonic distortion minimization for three-level neutral-point-clamped (NPC) inverters. The proposed method is first presented for three-level NPC inverters, and then, generalized for odd n-level inverters including NPC and cascaded inverters. With the help of base voltage vectors, the odd n-level space vector diagram can be transformed into a two-level one on which the modulation analysis is conducted This strategy utilizes two zero CMV vectors and one virtual vector, which is the combination of two other vectors with equal duty-split cycle, thereby, reducing the CMV magnitude and suppressing low-frequency components of the CMV. The construction of space vector diagrams with virtual vectors leads to three switching sequences in which one switching sequence gives the best harmonic performance under the harmonic distortion analysis, thereby significantly reducing the output harmonic distortion. Therefore, the proposed reduced CMV PWM strategy achieves zero average CMV in one switching period, and minimized output harmonic distortion in comparison to the existing methods. Simulation and experimental results confirm the effectiveness of the proposed strategy.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Investigate and Reduce Capacitive Couplings in a Flyback Adapter With a
           DC-Bus Filter to Reduce EMI
    • Authors: Yiming Li;Shuo Wang;Honggang Sheng;Srikanth Lakshmikanthan;
      Pages: 6963 - 6973
      Abstract: In consumer electronics, high power density power adapters are designed to minimize the adapter size. As a result, the components are getting very close and the near-field coupling issue tends to be severe. This compromises the performance of electromagnetic interference filters, especially at high frequencies. This article investigates near-field capacitive couplings and the reduction techniques in a high power-density power adapter with a dc-bus filter. The parasitic capacitive coupling theory is developed and parasitic coupling capacitances are experimentally extracted. The common-mode (CM) noise model with parasitic capacitive couplings is developed and the techniques to reduce the CM noise due to parasitic capacitive couplings are explored. Simulation and experiments were conducted to verify the analysis and the proposed techniques.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Common Mode Noise Reduction of Three-Level Active Neutral Point Clamped
           Inverters With Uncertain Parasitic Capacitance of Photovoltaic Panels
    • Authors: Jianing Wang;Xiaohui Liu;Yuanwu Xun;Shaolin Yu;
      Pages: 6974 - 6988
      Abstract: SiC devices can upgrade the inverter performance to a new level by its potentially more than ten times higher switching speed compared to its Si counterpart. However, the high switching frequency and dv/dt, di/dt worsen the electromagnetic interference. Reduction of the common mode (CM) noise of the non-isolated photovoltaic (PV) inverters is addressed by many researchers through adding filters or balancing the circuit. However, most methods rely on the certainty of the parasitics in the system in advance. It is usually not practical for a PV inverter because the parasitic capacitance of PV panels that are to be installed in plants varies from case to case and further can be seriously affected by the damp environment. This article proposes a practical way to reduce the CM noise of the three-level active neutral point clamped (ANPC) inverters with uncertain parasitic capacitance of PV panels. First, the CM model of ANPC inverters with all parasitic capacitances is established. Next, most existing hardware-based reduction methods of the CM noise are summarized based on a unified mathematical model and further compared with each other. After the comparison, a practical method is proposed to reduce the CM noise of the ANPC inverter with uncertain parasitic capacitances, which just adds little volume and cost to the whole system. Finally, the simulation and experiments are conducted to validate the proposed method.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Common-Mode EMI Noise Analysis and Reduction for AC–DC–AC Systems With
           Paralleled Power Modules
    • Authors: Le Yang;Hui Zhao;Shuo Wang;Yongjian Zhi;
      Pages: 6989 - 7000
      Abstract: In this article, the common-mode (CM) noise model is developed for an ac–dc–ac system with paralleled power modules. The CM noise contributions from both rectifiers and motor drives are analyzed. The interaction between the ac/dc rectifiers and dc/ac motor drives is explored. The CM noise reduction techniques which include a decoupling inductor technique and a CM noise balance technique are proposed to reduce the CM noise on the ac input side. Experiments and simulations were conducted to validate the developed CM noise model, rectifier and inverter interaction theory and CM noise reduction techniques.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Output Impedance Modeling and High-Frequency Impedance Shaping Method for
           Distributed Bidirectional DC–DC Converters in DC Microgrids
    • Authors: Qi Zhang;Jiangjiang Li;Rongwu Zhu;Fujin Deng;Xiangdong Sun;Shaoliang An;Marco Liserre;
      Pages: 7001 - 7014
      Abstract: Output impedance characteristics of interfaced converters of energy sources are the important indicators to assess the anti-interference ability of the dc microgrids. However, the output impedance is often approximately modeled by neglecting the impacts of delay units. In order to accurately study the anti-interference ability, the output impedance of an energy storage system is modeled with the consideration of the coupling characteristics of the current control gains and the delays caused by digital control and switching. The constraint mechanism of the coupling factors to impact the effective bandwidth of current loop in a load current feedforward system is also revealed. Then, an impedance shaping method is proposed to improve the anti-interference ability by optimally shaping the high-frequency output impedance, and also to improve system performances in terms of increasing the bandwidth of inner loop and the stable margin of outer loop. The simulation and experimental results both clearly validate the correctness and feasibility of the proposed impedance shaping method.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Interleaved Current-Fed Switched Inverter
    • Authors: Sonam Acharya;Santanu Kumar Mishra;
      Pages: 7015 - 7030
      Abstract: Current-fed switched inverter (CFSI) is a high-gain inverter topology suitable for applications which have limited input dc source voltage, e.g., roof-top solar applications. A very high step-up ratio between ac output and dc input along with inherent shoot-through protection makes it suitable for low-power stand-alone inverter applications. In this article, a novel interleaved topology for CFSI (ICFSI) is proposed to augment its power rating. A pulsewidth modulation (PWM) scheme is also proposed to drive the interleaved topology. Various modes of operation of ICFSI, along with the steady-state model and dynamic analysis, with the proposed PWM scheme, are reported. ICFSI, with the PWM scheme, results in a 33% increase in maximum ac gain as compared to CFSI. In this article, the small-signal model of ICFSI is also derived and verified. An analysis comparing the losses in CFSI and ICFSI is carried out. It is observed that interleaved operation improves the efficiency by 4% at 600 W. The proposed topology and analysis are verified with the experimental results obtained from a 600-W laboratory-developed prototype.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Nonlinear Control Operation of DFIG-Based WECS Incorporated With Machine
           Loss Reduction Scheme
    • Authors: Ifte Khairul Amin;Mohammad Nasir Uddin;
      Pages: 7031 - 7044
      Abstract: This article presents a novel adaptive backstepping based nonlinear control scheme incorporated with machine loss reduction and parameter uncertainties for grid-connected doubly fed induction generator (DFIG) driven wind energy conversion system (WECS). The proposed nonlinear controller is developed to stabilize both the grid and rotor side current control loops of direct-drive DFIG-based WECS. Traditional feedback linearization controllers are sensitive to system parameter variations and disturbances on DFIG-based WECS, which demands advanced control techniques for stable and efficient performance considering the nonlinear system dynamics. The proposed nonlinear controller incorporates the system uncertainty and nonlinearities while ensuring the stability of the drive system through Lyapunov stability criteria. A machine loss reduction algorithm is also incorporated to achieve enhanced efficiency. The performance of the proposed nonlinear scheme is compared with conventional benchmark fixed gain proportional-integral control and sliding mode control scheme for the rotor-side converter controller. The proposed nonlinear controller for DFIG-based WECS integrated with machine loss reduction scheme is successfully implemented in real time using DSP board DS 1104 for a prototype 350 W DFIG. The simulation and experimental results prove the efficacy of the proposed scheme under variable operating conditions such as wind speed variation, grid voltage disturbances, and parameter uncertainties.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Coupled Inductor-Based High Voltage Gain DC–DC Converter For
           Renewable Energy Applications
    • Authors: Afshin Mirzaee;Javad Shokrollahi Moghani;
      Pages: 7045 - 7057
      Abstract: In this article, a novel coupled inductor-based high step-up dc–dc converter is proposed. The introduced converter benefits from various advantages, namely ultrahigh voltage gain, low voltage stress on the power switches, and continuous input current with low ripple. Therefore, the presented converter is suitable for renewable energy applications. By utilizing clamped circuit, voltage spike of the active switch is clamped during the turn-off process. Hence, a switch with low $R_{text{DS-on}}$ can be used, which reduces the conduction losses as well as the cost of the converter. Furthermore, the energy of leakage inductance is used to obtain zero voltage switching (ZVS) for the main and auxiliary switches. Additionally, the output diode current falling rate is controlled by leakage inductance; thus, reverse-recovery problem of output diode is alleviated. The steady-state analysis and design considerations of the proposed converter are discussed. Finally, a 250-W experimental prototype of the presented converter is implemented to validate the converter operation and the theoretical analysis.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Integrated Common and Differential Mode Filter With Capacitor-Voltage
           Feedforward Active Damping for Single-Phase Transformerless PV Inverters
    • Authors: Ricardo Souza Figueredo;Lourenço Matakas;
      Pages: 7058 - 7072
      Abstract: Recently, several publications have discussed the design of LCL filters and current controllers for grid-connected converters. However, the focus was the LCL filter used as a differential mode (DM) filter. Besides its conventional application as DM filter, a modified LCL filter configuration can be used as an integrated common mode (CM) and DM filter, which is particularly interesting for transformerless photovoltaic (PV) inverters, whereby the CM leakage current must be limited to comply with standards. This article proposes the joint design procedure for an integrated CM and DM filter plus the current controller used in single-phase grid-connected transformerless PV inverters. The increased number of components and resonance frequencies, compared to the conventional LCL filter, requires a careful analysis of the location of resonance and anti-resonance frequencies, taking into account parameters variation. The design procedure considers the extended region of stability for the DM resonance frequency allocation provided by the filter capacitor-voltage feedforward active damping with converter-side current feedback. It also considers continuous and discontinuous unipolar pulsewidth modulation. Design examples and simulation results for 1.5 and 10 kVA are presented. The effectiveness of the proposed design procedure is verified by experimental results obtained from a 1.5 kVA inverter.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Quasi-Two-Stage Multifunctional Photovoltaic Inverter With Power Quality
           Control and Enhanced Conversion Efficiency
    • Authors: Jiangfeng Wang;Kai Sun;Hongfei Wu;Li Zhang;Jianxin Zhu;Yan Xing;
      Pages: 7073 - 7085
      Abstract: A novel quasi-two-stage multifunctional inverter (QMFI) for photovoltaic (PV) applications is proposed in this article. With the help of the quasi-two-stage architecture, part of active power can be directly transferred from PV arrays to the grid or load within a single power conversion stage and hence improve the efficiency. In addition to active power transfer, both the realization of maximum power point tracking (MPPT) and compensation of nonactive current (i.e., reactive, harmonic, or unbalanced current) of the QMFI are considered. A mathematical model of the QMFI is presented to guide the control parameter design. Meanwhile, an analysis model based on the rotating frame is proposed to derive the space vector pulsewidth modulation strategy of the QMFI, and also, offer straightforward insight into the influence of nonactive current compensation on quasi-two-stage active power flow. Compared with traditional solutions, the QMFI can realize active power delivery with higher efficiency and also keep functions of achieving MPPT and enhancing power quality. The feasibility and effectiveness of the proposed solution are verified with a 3-kVA prototype.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Design of Hybrid Artificial Bee Colony Algorithm and Semi-Supervised
           Extreme Learning Machine for PV Fault Diagnoses by Considering Dust Impact
           
    • Authors: Jun-Ming Huang;Rong-Jong Wai;Geng-Jie Yang;
      Pages: 7086 - 7099
      Abstract: Photovoltaic (PV) systems operating in the outdoor environment are vulnerable to various factors, especially dust impact. Abnormal operations lead to massive power losses, and severe faults as short circuit may cause safety problems and fire hazards. Therefore, monitoring the operation status of PV systems for timely troubleshooting potential failure and effective cleaning scheme are the focus of current research works. In this study, I–V characteristics of PV strings under various fault states are analyzed, especially soiling condition. Because labeled data for PV systems with specific faults are challenging to record, especially in the large-scale ones, a novel algorithm combining artificial bee colony algorithm and semi-supervised extreme learning machine is proposed to handle this problem. The proposed algorithm can diagnose PV faults using a small amount of simulated labeled data and historical unlabeled data, which greatly reduces labor cost and time-consuming. Moreover, the monitoring of dust accumulation can warn power plant owners to clean PV modules in time and increase the power generation benefits. PV systems of 3.51 and 3.9 kWp are used to verify the proposed diagnosis method. Both numerical simulations and experimental results show the accuracy and reliability of the proposed PV diagnostic technology.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Active-Clamped Zero-Current Switching Current-Fed Half-Bridge Converter
    • Authors: Cassiano Ferro Moraes;Emerson Giovani Carati;Jean Patric da Costa;Rafael Cardoso;Carlos Marcelo de Oliveira Stein;
      Pages: 7100 - 7109
      Abstract: This article presents an auxiliary circuit for the current-fed half-bridge (CFHB) converter, aiming to clamp the high voltage spikes across the main switches caused by the energy stored in the leakage inductance of the transformer. This circuit also provides zero-current switching (ZCS) to the main switches at turn-off. Moreover, the rectifier diodes and the auxiliary switch operates under ZCS at turn-on and turn-off. Another feature of the proposed circuit is that it is composed of just one active switch, reducing the number of auxiliary sources and drivers compared to the conventional active-clamped CFHB converter. In addition, the inclusion of the clamping circuit increases the voltage ratio of the converter. A 300-W prototype was built to validate the analysis and design proposed in this article. The converter was tested for various load conditions at 100 kHz, and a peak efficiency of 96.2% was obtained. Also, a comparison of efficiency for the CFHB employing other conventional clamping circuits is presented.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • MPPT for Electromagnetic Energy Harvesters Having Nonnegligible Output
           Reactance Operating Under Slow-Varying Conditions
    • Authors: Kimberley Hiu-kwan Tse;Henry Shu-hung Chung;
      Pages: 7110 - 7122
      Abstract: Most maximum power point trackers (MPPTs) for electromagnetic energy harvesters (EMEHs) are based on resistive matching technology, where the input resistance of the MPPT is made equal to the magnitude of the output impedance of the harvester. This is valid when the output reactance of the EMEH is much smaller than its output resistance. However, some EMEHs, such as permanent magnet generator, have nonnegligible output reactance. The discrepancy between the power extracted by the resistive matching technology and the maximum extractable power will increase as the output reactance increases. Under high excitation frequency and low operating temperature, the effect of the output reactance will become more dominant. In order to deal with such issue, an MPPT that can counteract the effect of the coil inductance and match with the coil resistance is presented. It does not require knowing coil parameters a priori and the harvester will be operated at its true maximum power point. A 7-W prototype for testing the proposed algorithm has been built and evaluated. Its performance is favorably compared with the amount of power extracted with the resistive matching technology.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Compound Voltage Clamped Class-E Converter With ZVS and Flexible Power
           Transfer for WPT System
    • Authors: Liangzong He;Dong Guo;
      Pages: 7123 - 7133
      Abstract: The class-E converter with soft-switching has been widely used in high-frequency wireless power transfer (WPT) system. However, the high voltage stress on the switch limits its application. In this article, a compound voltage-clamped class-E converter, consisting of an auxiliary clamped circuit and class-E converter, is proposed in the WPT system to solve the issue. Through impedance analysis, SP (series–parallel) resonance network is employed for the proposed converter to reach high transfer efficiency. Meanwhile, based on the analysis of voltage stress on the switches and the boundary condition for zero-voltage-switch (ZVS) operation, the optimal operation region could be obtained, leading to a reduced voltage stress and switching loss together. Moreover, as the conduction duty-cycle becomes a controllable freedom in the proposed converter, the relationship between conduction duty cycle and output power is given out, which makes power transfer more flexible while maintaining ZVS operation synchronously. Finally, a prototype was built to verify the performance of the proposed topology, and the experiments agreed well with the calculation.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A Compact Resonant Switched-Capacitor Heater for Lithium-Ion Battery
           Self-Heating at Low Temperatures
    • Authors: Yunlong Shang;Kailong Liu;Naxin Cui;Nan Wang;Ke Li;Chenghui Zhang;
      Pages: 7134 - 7144
      Abstract: Lithium-ion (Li-ion) batteries endure substantial energy loss and power recession under cold environments, requiring to be heated before starting normal operations in electric vehicles (EVs). Currently, many internal ac heating approaches powered by batteries have been proposed to achieve a fast heating speed, high efficiency, and good uniformity. However, due to the bulky size, high cost, and low ac heating frequency, the existing ac heating devices are generally improper for EV applications. In the light of this, a compact high-frequency heater is proposed in this article to achieve effective self-heating for Li-ion batteries. Specifically, based upon the resonant switched capacitors (RSCs), this heater is only powered by the on-board battery pack, leading to an easy implementation. Detailed analytical expressions of the heating current and efficiency are deduced and validated through various experiments. Illustrative results demonstrate that the proposed RSC heater is capable of effectively realizing battery self-heating without using external devices. Particularly, a reliable tradeoff between the fast heating speed (2.67 °C/min) and high efficiency (96.4%) is obtained by using two or more parallel-connected heaters. Due to the compact size, low price, high efficiency, and good reliability, the proposed heater can be also extended to preheat batteries of unmanned aerial vehicles, robots, phones, etc.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A Study of T-Type and ZVS-PWM Full-Bridge Converters for Switch-Mode Power
           Supplies
    • Authors: Javad Khodabakhsh;Gerry Moschopoulos;
      Pages: 7145 - 7159
      Abstract: The zero-voltage switching (ZVS) T-type dc–dc converter has been proposed as an alternative to the conventional ZVS pulsewidth modulated (PWM) full-bridge (FB) converter. Although it has a number of advantageous features, the ZVS T-type dc–dc converter is not well known among power electronic engineers, and the topology has thus been neglected. In this article, the operation of the dc–dc ZVS T-type converter is reviewed and contrasted to that of the conventional ZVS-PWM-FB dc–dc converter. Results obtained from prototypes of each converter topology are then presented, compared, and discussed, and conclusions about which converter is superior for particular applications are made.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Design and Model of Series-Connected High-Voltage DC Multipliers
    • Authors: Mahran Quraan;Ahmad Zahran;Ahmed Herzallah;Ahmad Ahmad;
      Pages: 7160 - 7174
      Abstract: The generation of high dc voltages is necessary for feeding many technical applications and testing the insulation material of high-voltage dc transmission lines and ac power cables with long lengths. The article proposes a modular multiplier high-voltage dc generator with integrated Cockcroft–Walton (CW) circuits. In this new topology, CW circuits are connected in series to produce a high dc output voltage with low regulation factor (
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Generalized Cockcroft-Walton Multiplier Voltage Z-Source Inverters
    • Authors: Xinping Ding;Yun Liu;Delin Zhao;Weimin Wu;
      Pages: 7175 - 7190
      Abstract: An impedance-source inverter can offer the voltage buck-boost function in a single-stage circuit. Its advantages include a simple structure, safety, and reliability. This article proposes a Cockcroft–Walton multiplier voltage (CWMV) impedance-source inverter consisting of a modified CWMV circuit and an impedance-source inverter. There are two types of circuits: the CWMV Z-source inverter (ZSI) and the CWMV quasi-Z-source inverter (qZSI). In a CWMV qZSI, the input current is continuous, the voltage overshoot across the bridge is small, and the boost capability is great, with the disadvantage is that its passive component count is increased. This article studies the static and dynamic characteristics of the two inverters. The operating modes of the CWMV qZSI is studied, the voltage and current stress of each device are analyzed, the small signal model of the circuit is established, and a proportional-integral-differential controller with good control performance is designed. Compared with existing impedance-source inverters, a CWMV qZSI has obvious advantages in terms of the voltage and current stresses on components, and also in terms of its inductor size, magnetic core volume, and overall efficiency. The theoretical analysis was verified by a 1 kW laboratory prototype. The experimental results were consistent with the theoretical analysis.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A Novel Interleaved Nonisolated Bidirectional DC–DC Converter With High
           Voltage-Gain and Full-Range ZVS
    • Authors: Zhixing Yan;Jun Zeng;Weijie Lin;Junfeng Liu;
      Pages: 7191 - 7203
      Abstract: A nonisolated soft-switching bidirectional dc–dc converter (BDC) with interleaved technique and built-in transformer (BT) is proposed for the interface between the energy storage system and dc microgrid bus in this article. A T-type neutral-point-clamped circuit is integrated into an interleaved conventional buck–boost BDC to obtain a high voltage-gain ratio and decrease voltage stresses of power switches effectively. Compared with the couple-inductor, BT allows for a small magnetic core size, owing to its inherent saturation avoidance. The interleaved structure is employed to reduce the current ripple in the low-voltage side and helps to achieve voltage matching on both sides of the BT under pulsewidth modulation control. Thus, the circulating current can be lowered to improve efficiency. Phase-shift control is adopted to regulate the power flows of the proposed BT-BDC. Moreover, the optimal design is given for the component parameters to accomplish zero-voltage switching in a wide voltage range, which can reduce the switching losses. The operational principles and characteristics of the proposed BT-BDC are presented in detail. The analysis and performance have been fully validated experimentally on a 40–60 V/400 V 1-kW prototype. The accordance between the analysis and the experimental results further testifies the advantages.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Passive Resonant Level Shifter for Suppression of Crosstalk Effect and
           Reduction of Body Diode Loss of SiC MOSFETs in Bridge Legs
    • Authors: Ho-Tin Tang;Henry Shu-Hung Chung;John Wing-To Fan;Ryan Shun-Cheung Yeung;Ricky Wing-Hong Lau;
      Pages: 7204 - 7225
      Abstract: Due to the presence of parasitic elements in switching devices and circuit realization, crosstalk phenomenon in bridge-leg configurations is unavoidable. A passive resonant level shifter that can suppress the effect of the crosstalk and deliver a low off-state gate-source voltage to reduce the forward voltage drop of the body diode of SiC mosfets is presented. The circuit is composed of two parts. The first one is a resistor-capacitor-diode (RCD) level shifter that delivers a static negative off-state gate-source voltage to the mosfets. The voltage level is designed to be close to zero, so that the forward voltage drop of the body diode is lowered. The second one is a series resonant tank circuit. It generates short voltage pulses to counteract the voltage pulses caused by the crosstalk. The gate-source voltage can then be maintained at a level below the threshold voltage of the mosfets. The proposed level shifter does not require any active devices or additional supply. It can be applied readily to commercially available gate drivers. A passive resonant level shifter module for four SiC mosfets in a 1-kW H-bridge inverter has been built and evaluated. Detailed performance comparison with the RCD level shifter will be given.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A Single-Switch Single-Magnetic Core High Conversion Ratio Converter With
           Low Input Current Ripple and Wide Soft-Switching Range for Photovoltaic
           Applications
    • Authors: Milad Heidari;Hosein Farzanehfard;Morteza Esteki;
      Pages: 7226 - 7234
      Abstract: In this article, a novel high conversion ratio dc–dc converter suitable for photovoltaic applications is presented. Utilizing single-switch and single-magnetic core, low ripple input current and low voltage stress across the semiconductors are the major advantages of the proposed converter. In order to provide a soft-switching condition for the converter switch at a wide range of output power, a passive lossless snubber is employed. The presented converter is adequate for photovoltaic applications due to the mentioned properties. Operating principles are analyzed and design considerations are provided. In order to validate the theoretical analysis, a prototype of the proposed converter is implemented and the experimental results are exhibited.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Efficient Microchannel Cooling of Multiple Power Devices With Compact Flow
           Distribution for High Power-Density Converters
    • Authors: Remco van Erp;Georgios Kampitsis;Elison Matioli;
      Pages: 7235 - 7245
      Abstract: In this article, we describe a new approach for the compact and energy-efficient cooling of converters where multiple miniaturized microfluidic cold plates are attached to transistors providing local heat extraction. The high pressure drop associated with microchannels was minimized by connecting these cold plates in parallel using a compact three-dimensional-printed flow distribution manifold. We present the modeling, design, fabrication, and experimental evaluation of this microfluidic cooling system and provide a design strategy for achieving energy-efficient cooling with minimized pumping power. An integrated cooling system is experimentally demonstrated on a 2.5-kW switched-capacitor dc–dc converter, cooling down 20 GaN transistors. A thermal resistance of 0.2 K/W was measured at a flow rate of 1.2 mL/s and a pressure drop of 20 mbar, enabling the cooling of a total of 300 W of losses in the converter using several milliwatt of pumping power, which can be realized with small micropumps. Experimental results show a tenfold increase in power density compared with the conventional cooling, potentially up to 30 kW/L. This proposed cooling approach offers a new way of coengineering the cooling and the electronics together to achieve more compact and efficient power converters.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Hybrid Buck–Boost Multioutput Quasi-Z-Source Converter With Dual DC
           and Single AC Outputs
    • Authors: Kharan Shiluveru;Akash Singh;Anish Ahmad;Rajeev Kumar Singh;
      Pages: 7246 - 7260
      Abstract: This article presents two hybrid multioutput buck–boost quasi-Z-source converters (q-ZSCs) capable of giving two dc and one ac outputs simultaneously from a single dc input. One dc and the ac outputs of the proposed multioutput q-ZSCs have both buck and boost capabilities and the other dc output has the property of boosting the input voltage, thereby capable of giving a wide range of voltage gain both for dc and ac outputs. The rationale behind proposing two variants of the hybrid multioutput q-ZSCs is to have more flexibility on voltage gains as per the load requirements. The proposed converters are derived from the quasi-Z-source concept and hence inherit all the properties of q-ZSI, which realize buck/boost, single-stage inversion, and power conditioning with improved reliability along with inherent shoot-through protection capability. All the three outputs of the proposed converters can be independently controlled making them suitable for various applications. The proposed converters can be utilized for various modern multioutput dc–dc and dc–ac power conversion applications, such as renewables and the uninterrupted power supplies. Detailed steady-state operation, loss/efficiency analysis of the proposed converter, and discussion on the hybrid pulsewidth modulation are presented in this article. In order to bring out the advantages of the proposed multioutput converter, a detailed comparative analysis among the proposed and other closely related existing multioutput converters is carried out in this article. A 310-W prototype is developed to verify the performance of the proposed multioutput buck–boost q-ZSC.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A Novel Finite-Control-Set Model Predictive Current Control for Five-Phase
           PM Motor With Continued Modulation
    • Authors: Wenxiang Zhao;Tao Tao;Jihong Zhu;Huajun Tan;Yuxuan Du;
      Pages: 7261 - 7270
      Abstract: The conventional five-phase finite-control-set model predictive control (FCS-MPC) suffers from heavy computational burden. Meanwhile, the control set with finite vectors inevitably leads to deteriorated operation performance. This article proposes a novel FCS model predictive current control (MPCC) with continued modulation. A cascaded optimization procedure is proposed, which includes main virtual voltage vector (VV) selection, determination of optimal combination of adjacent two VVs, and amplitude optimization. In this cascaded optimization procedure, the phase angle and the amplitude of the synthesized vector can be obtained in different steps. Also, there are two duty cycles calculated in different steps independently, which avoid overflow. By using this cascaded procedure, the continued modulation can be realized without using a modulator. Meanwhile, a vector selection method is introduced to reduce computational burden. This vector selection method avoids evaluation of all the candidate vectors without any negative effects. Moreover, the merits of conventional FCS-MPCC can be preserved. The experimental results verify the effectiveness and superiority of the proposed FCS-MPCC method.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • An MRAS Speed Observer Based on Control Winding Flux for Sensorless
           Control of Stand-Alone BDFIGs
    • Authors: Wei Xu;Alameen K. Ebraheem;Yi Liu;Jianguo Zhu;Mohamed G. Hussien;Omer Mohammed Elbabo Mohammed;
      Pages: 7271 - 7281
      Abstract: This article presents a new rotor speed observer for the sensorless control of stand-alone brushless doubly fed induction generators based on the control winding flux model reference adaptive system structure. The observer is incorporated in the control strategy for regulating the terminal voltage magnitude and frequency under the different operating conditions. The capability of the proposed observer and control method is demonstrated by comprehensive simulation results and verified by experiments. As shown, without using physical speed sensors, the sensorless control algorithm incorporating the proposed speed observer can effectively maintain the amplitude and frequency of power winding voltage constant at different rotor speeds and under different conditions of load and machine parameter, e.g., inductance and/or resistance, variations.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Predictive Torque Control Algorithm for a Five-Phase Induction Motor Drive
           for Reduced Torque Ripple With Switching Frequency Control
    • Authors: Apekshit Bhowate;Mohan V. Aware;Sohit Sharma;
      Pages: 7282 - 7294
      Abstract: This article presents a progressive comparison of predictive torque control (PTC) algorithms for a five-phase induction motor fed with a two-level five-phase inverter. The extension of three-phase PTC to the five-phase motor, introduces current harmonics of the order 10n $pm$ 3 (n = 0, 1, 2.. .), which are not responsible for torque/flux production. The inherent disadvantage of PTC is being a variable frequency algorithm, which adds complexity to the design of magnetic components. This disadvantage of PTC can be overcome by applying dwell time ($t_{s}$) to the voltage vectors obtained through a minimum torque ripple condition, which is determined based on the ripple equation. In the proposed algorithm, a set of synthetic voltage vectors are generated and used for reducing flux and torque error through cost function. The use of synthetic voltage vector simplifies the cost function and further reduces the computation time. A two-step delay compensation is adopted to improve the precision of the control algorithm further. In each control cycle, an optimal switching time is calculated to reduce the torque ripple and to maintain the constant switching frequency. In this article, a modified PTC is proposed, which targets to achieve constant switching frequency, eliminate the xy-subspace current harmonics, reduce the torque ripple, and minimize the computational burden involved in the conventional predictive torque control algorithm. The experimental study is carried out on a laboratory prototype. The results show compliance with all the experimental study with different PTC algorithms with different sampling frequencies, and the modified cost function.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A High-Voltage DC–DC Buck Converter With Dynamic Level Shifter for
           Bootstrapped High-Side Gate Driver and Diode Emulator
    • Authors: Bing Yuan;Jing Ying;Wai Tung Ng;Xin-Quan Lai;Ling-Fei Zhang;
      Pages: 7295 - 7304
      Abstract: Considering the propagation delay, dVSW/dt immunity, and power dissipation issues in the bootstrapped high-side gate driver design, a monolithic high-voltage dc–dc buck converter with a high-speed dynamic level shifter and improved gate drive buffer is presented in this article. With the introduction of instantaneous dynamic current, the propagation delay of the level shifter is reduced to 1.13 ns for the high-side switch. The dVSW/dt immunity is enhanced by a dynamic current compensation during positive slewing and a diode voltage clamp during negative slewing. The average current consumption of the level shifter is only 8.45 μA at a switching frequency of 1 MHz. The proposed gate drive buffer eliminates the shoot-through current with the use of dead-time control. The compact level shifter and buffer are also used to drive an integrated p-channel mosfet transistor serving as a bootstrap diode emulator. Experimental results show that the fabricated converter with the proposed scheme regulates well with an 18 V input, 1.05 V output, and 2 A load current. Also, high efficiency of up to 93% is achieved.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Decoupled Floating Capacitor Voltage Control of a Dual Inverter Drive for
           an Open-Ended Winding Induction Motor
    • Authors: Chatumal Perera;Gregory J. Kish;John Salmon;
      Pages: 7305 - 7316
      Abstract: A control scheme is presented for a dual inverter drive with a floating capacitor bridge, with decoupled motor and capacitor dynamics. A stator current reference frame is used that decouples the real and reactive power components of the motor and enables the decoupling of the motor and capacitor dynamics. Apart from the high frequency voltage ripple due to the inverter switching pattern, the capacitor voltage can be kept constant even during large step changes in motor speed reference and load torque. This allows for the use of a significantly smaller floating bridge capacitor whose size depends only on the steady-state high frequency voltage ripple. Additionally, the number of PI regulators used compared to previous works and the dc-link voltage requirements are both reduced.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Optimal Dipole-Coil Ampere-Turns Design for Maximum Power Efficiency of
           IPT
    • Authors: Byeong G. Choi;Ji H. Kim;Eun S. Lee;Hoi R. Kim;Chun T. Rim;
      Pages: 7317 - 7327
      Abstract: An optimal ampere-turns design for a long-distance dipole-coil-based inductive power transfer (IPT) system for maximum power efficiency is proposed in this article. Assuming that specific requirements, which are the target load power, the physical size of the transmitting (Tx) and receiving (Rx) coils, and the distance between the Tx and Rx coils, are given, quantitative analyses on the optimal ampere-turns of loosely coupled Tx and Rx coils to satisfy the constraints with maximum power efficiency have been conducted in this article. With the proposed design process, the IPT system is expected to be designed and fabricated with minimal cost and time. The maximum experimental error is only 8.8% when the delivery power ranges from 20–200 W in the experiment results, thus demonstrating that the method proposed in this article can suggest a viable design direction of the IPT system.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Efficient Permanent Magnet Temperature Modeling and Estimation for Dual
           Three-Phase PMSM Considering Inverter Nonlinearity
    • Authors: Guodong Feng;Chunyan Lai;Wenlong Li;Ze Li;Narayan C. Kar;
      Pages: 7328 - 7340
      Abstract: Accurate temperature information is crucial to dual three-phase permanent magnet synchronous machine (DT-PMSM) drives. Therefore, this article proposes two efficient models for permanent magnet temperature estimation of DT-PMSMs. The proposed models are derived through current injection in the reference frame that does not contribute to torque production. Through current injection, the proposed models can fully explore the two sets of machine equations to cancel winding resistance and machine inductances. To improve the estimation performance, inverter nonlinearity is compensated in the first model and cancelled in the second model. In comparison to existing methods, the proposed approach is computationally efficient and robust to parameter variation, magnetic saturation, and inverter nonlinearity. Moreover, the current injection will not affect the machine torque production and control performance. The proposed estimation approach is evaluated on a laboratory DT-PMSM under various operating conditions.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Position Sensorless Drive and Online Parameter Estimation for
           Surface-Mounted PMSMs Based on Adaptive Full-State Feedback Control
    • Authors: Yu Yao;Yunkai Huang;Fei Peng;Jianning Dong;
      Pages: 7341 - 7355
      Abstract: In this article, a position sensorless drive and online parameter estimation method for surface-mounted permanent magnet synchronous machines-based on adaptive full-state feedback current control is proposed. The position sensorless drive is established by the detection of the back-electromotive force in the $gamma delta$ synchronous reference frame, which is effective at the medium-speed and high-speed range. Besides, accurate estimation of the winding resistance, the stator inductance, and the flux linkage of the PM is achieved independently. Compared with the traditional recursive-least-square methods, the proposed parameter identification method can be easily implemented because of the significantly reduced execution time. With the help of the parameter identification, the precise position estimation can be achieved by the proposed sensorless control method regardless of the parameter variation during the operation. The stability of the proposed method is proved by the Lyapunov-function method. Finally, the effectiveness of the proposed method is validated by the simulation and experimental results.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • An Envelope-Prediction-Based Sensorless Rotor Position Observation Scheme
           for LCI-Fed EESM at Zero and Low Speed
    • Authors: Jiabao Kou;Qiang Gao;Yongxiao Teng;Jin Ye;Dianguo Xu;
      Pages: 7356 - 7365
      Abstract: An envelope-prediction-based sensorless rotor position observation scheme is proposed for a load commutated inverter (LCI)-fed electrically excited synchronous motor (EESM) at zero and low speed. The proposed rotor position observation scheme does not need to utilize the full controlled power device, nor to modify the LCI drive topology. An interval trigger mode for the exciter control is proposed to generate the appropriate fixed-frequency injected signal. The bandpass filters (BPFs) are optimized to extract the target signal, and the observation error due to the BPF is analyzed and compensated. A specific signal sampling method and an envelope-prediction algorithm are presented to simplify calculation and improve the observation accuracy. A normalized phase-locked loop is designed such that the observer has a better observational performance. Finally, the proposed rotor position observation scheme is verified by a 15-kW LCI-fed EESM experimental platform.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Maximum Thrust per Ampere of Linear Induction Machine Based on Finite-Set
           Model Predictive Direct Thrust Control
    • Authors: Wei Xu;Mahmoud Fouad Elmorshedy;Yi Liu;Jose Rodriguez;Cristian Garcia;
      Pages: 7366 - 7378
      Abstract: One of the methods that is used to increase the efficiency of the linear induction machine (LIM) is the maximum thrust per ampere (MTPA), where the same thrust can be achieved with a lower value of the primary current. Consequently, the power loss can be decreased and the efficiency be increased. However, so far, no quantitative focus exists to increase the efficiency of the LIM. This article proposes the MTPA-based finite-set model predictive control. The concept of field-oriented control is used to achieve the condition of MTPA. Based on this condition, the proposed control method can be developed by adjusting the value of the primary flux linkage. The proposed control method depends on both thrust and primary flux linkage and this proposed method is called finite-set model predictive direct thrust control (FS-MPDTC). Comparison between the FS-MPDTCs with and without MTPA is presented to illustrate the effectiveness of the proposed method. A prototype test platform is developed in the laboratory with two 3 kW arc induction machines to verify the proposed method. Analysis for both comprehensive simulation and experimental results are conducted in this article.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Permeance Distribution Function: A Powerful Tool to Analyze
           Electromagnetic Forces Induced by PWM Current Harmonics in Multiphase
           Surface Permanent-Magnet Motors
    • Authors: Yajun Lv;Siwei Cheng;Zhongkun Ji;Dong Wang;Junquan Chen;
      Pages: 7379 - 7391
      Abstract: This article introduces a new method to analyze electromagnetic forces induced by pulsewidth modulation current harmonics in inverter-fed surface permanent-magnet motors. The concept of the permeance distribution function (PDF) is first introduced with its properties and relation to machine inductances fully explained. Utilizing the concept of PDFs, two methods are proposed to calculate the flux distribution on stator boundaries by armature currents and rotor permanent magnets, respectively. By superposing the stator flux distributions from both sources, the final stator electromagnetic force distribution is obtained. The method is validated by finite-element analysis, demonstrating good accuracy and very fast computation time.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Effect of Asymmetric Layout and Unequal Junction Temperature on Current
           Sharing of Paralleled SiC MOSFETs With Kelvin-Source Connection
    • Authors: Cheng Zhao;Laili Wang;Fan Zhang;
      Pages: 7392 - 7404
      Abstract: Parallel connection of silicon carbide (SiC) mosfets is a popular solution for high-capacity applications. In order to improve the switching speed of paralleled SiC mosfets, Kelvin-source connection is widely employed. However, the influences of asymmetric layout and unequal junction temperature on current sharing of paralleled SiC mosfets with Kelvin-source connection are not clear. This article addresses the issue for the first time by theoretical analysis and experimental verifications. The mechanism of current imbalance resulting from asymmetric layout and unequal junction temperature in the case with Kelvin-source connection is comprehensively investigated. Then, some significant discoveries are obtained. The static current sharing performance can be affected by drain and power source parasitic inductance, which is seldom mentioned before. Besides, this article first points out that the effect of power source parasitic inductance on dynamic current sharing is dominant compared with other parasitic inductance. What is more, the thermal–electric analyzing results suggest that there is a risk of thermal runaway for paralleled SiC mosfets with Kelvin-source connection at high switching frequency due to positively temperature-dependent dynamic current and switching losses. Based on the discoveries, some guidelines are provided for layout design and application of paralleled SiC mosfets with Kelvin-source connection.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Review of Loss Distribution, Analysis, and Measurement Techniques for GaN
           HEMTs
    • Authors: Jacob Gareau;Ruoyu Hou;Ali Emadi;
      Pages: 7405 - 7418
      Abstract: In recent years, there has been a trend for improved performance in semiconductor switches, allowing power electronic systems to achieve higher efficiency and higher power density. This desired improvement has led to the adoption of wide-bandgap devices-based switches due to the fact that silicon (Si) has been reaching its material limit. Si carbide and gallium nitride (GaN) offer faster switching speeds. Therefore, they require higher level measurement technologies to analyze them. In this article, the theoretical loss breakdown of a GaN-based power electronic system is presented including an analysis of its dynamic behavior. Several methods of measurement are presented to quantify the behavior of fast switching.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Synchronous Rectifiers Drain Voltage Overshoot Reduction in PSFB
           Converters
    • Authors: Manuel Escudero;Matteo-Alessandro Kutschak;David Meneses;Diego Pedro Morales;Noel Rodriguez;
      Pages: 7419 - 7433
      Abstract: The requirements for the blocking voltage of the rectification devices on the secondary side of phase shift full bridge (PSFB) dc–dc converter topology are, by nature, higher than for other quasiresonant or fully resonant topologies (DAB, LLC). This is especially aggravated in wide range operation converters and further increased by the rectifiers’ drain voltage overshoot. Unlike other resonant topologies, the inductor at the output of the PSFB effectively decouples the capacitor bank from the rectification stage, which otherwise acts as a strong lossless snubber. Higher blocking voltage requirements for the rectification devices worsen their Figure of Merit, increasing their related losses and decreasing the overall efficiency of the converter. In this article, the main causes of the rectifiers drain voltage overshoots in PSFB are analyzed. Design guidelines for the mitigation of the different causes are introduced, as well as a novel modulation scheme for the overshoot reduction, while the output filter operates in discontinuous conduction mode, without penalties in performance, complexity, or cost. A prototype of PSFB DC-DC converter of 3300 W, with 400-V input to 54.5-V output nominal voltages, was designed and built to test the proposed solutions achieving a peak efficiency of 98.12% at 50% of load.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Guidelines for the Design of Finite Control Set Model Predictive
           Controllers
    • Authors: Petros Karamanakos;Tobias Geyer;
      Pages: 7434 - 7450
      Abstract: Direct model predictive control (MPC) with reference tracking, also referred to as finite control set MPC (FCS-MPC), has gained significant attention in recent years, mainly from the academic community. Thanks to its applicability to a wide range of power electronic systems, it is considered a promising control method for such systems. However, to simplify the design, researchers frequently make choices that—often unknowingly—reduce the system performance. In this article, we discuss and analyze the factors that affect the closed-loop performance of FCS-MPC. Based on these findings, design guidelines are provided that help to maximize the system performance. To highlight the performance benefits, two case studies will be considered: the first one consists of a two-level converter and an induction machine, whereas the second one adds an $LC$ filter between the converter and the machine.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Intelligent Control of Microgrid With Virtual Inertia Using Recurrent
           Probabilistic Wavelet Fuzzy Neural Network
    • Authors: Kuang-Hsiung Tan;Faa-Jeng Lin;Cheng-Ming Shih;Che-Nan Kuo;
      Pages: 7451 - 7464
      Abstract: A microgrid with virtual inertia using master–slave control is proposed in this article to overcome the drawbacks of traditional inverter-based distributed generators for lack of inertia and without grid-forming capability. The microgrid using master–slave control is composed of a storage system, a photovoltaic (PV) system and a varying resistive three-phase load. The storage system and PV system are regarded as the master unit and the slave unit, respectively, in the microgrid. Moreover, in order to improve the reactive power control in grid-connected mode and the transient response of microgrid during the switching between the grid-connected mode and islanding mode, an online trained recurrent probabilistic wavelet fuzzy neural network (RPWFNN) is proposed to replace the conventional proportional-integral (PI) controller in the storage system. Furthermore, when the microgrid is operated in islanding mode, the load variation will have serious influence on the voltage control of the microgrid. Thus, the RPWFNN control is also proposed to improve the transient and steady-state responses of voltage control in the microgrid. Finally, according to some experimental results, excellent control performance of the microgrid with virtual inertia using the proposed intelligent controller can be achieved.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Adaptive Backstepping Control for Synchronous Reluctance Motor Based on
           Intelligent Current Angle Control
    • Authors: Faa-Jeng Lin;Ming-Shi Huang;Shih-Gang Chen;Che-Wei Hsu;Chia-Hui Liang;
      Pages: 7465 - 7479
      Abstract: The design and analysis of a novel current angle-based adaptive backstepping (ABS) speed control system for a synchronous reluctance motor (SynRM) drive system is presented in this article. First, a proportional-integral control system with field-oriented control is described. Owing to the unmodeled dynamics and magnetic saturation effects of the SynRM, currently, there is no predominant way to design the command of the d-axis current for the SynRM. Therefore, an ABS based on the current angle control (ABS-CAC) system is designed for the speed tracking of SynRM. The ABS speed tracking control is proposed to generate the stator current command, and a lookup table of the results of maximum torque per ampere (MTPA) analysis by using the finite element analysis method is proposed to provide the current angle commands. Moreover, to improve the transient dynamic response of SynRM under MTPA operating conditions, an intelligent speed transient control system using a recurrent Hermite fuzzy neural network is developed to generate the compensated current angle command. The proposed intelligent ABS-CAC is implemented in a 32-bit floating-point digital signal processor TMS320F28075. Finally, some experimental results are provided to demonstrate the robustness and effectiveness of the proposed control system.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Analysis and Improvement of Capacitance Effects in 360–800 Hz Variable
           On-Time Controlled CRM Boost PFC Converters
    • Authors: Xiaoyong Ren;Yuting Zhou;Zhehui Guo;Yu Wu;Zhiliang Zhang;Qianhong Chen;
      Pages: 7480 - 7491
      Abstract: In critical conduction mode (CRM) boost power factor correction (PFC) converters, the input filter capacitor (IFC) is used to limit the propagation of switching noise into the ac line and the inherently existing parasitic capacitance of power semiconductor devices resonates with the boost inductor to achieve soft switching, which is voltage dependent and nonlinear. However, IFC leads to the crossover distortion of the rectified input voltage and thus the zero-crossing distortion of input current, which is ignored at the utility line frequency (50–60 Hz) since the effect of IFC is relatively small in this case. However, for wide variable frequency (360–800 Hz) power system, the effect of IFC becomes severe and unnegligible, which causes the deterioration of input current total harmonics distortion (THD). Besides, the nonlinearity of the parasitic capacitance is ignored and an equivalent constant linear capacitance is used in existing variable on-time (VOT) controls, which will cause the inaccuracy of VOT control, and thus, exacerbates the input current distortion. In order to improve the input current THD at high line frequency, this article proposes the IFC compensation method to minimize the effect of IFC and a variable parameter control is also achieved to suppress the effect of nonlinear parasitic capacitance. The experimental results of an 115-Vac-input 160-W/270-Vdc-output CRM boost PFC prototype are presented to verify the effectiveness and advantages of the proposed VOT methods. With the proposed methods, the input current THD is only 2.04% at 360 Hz input with full load and 3.14% at 800 Hz input with full load.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A Fault-Tolerant Control Strategy for T-Type Three-Level Rectifier With
           Neutral Point Voltage Balance and Loss Reduction
    • Authors: Jie Chen;Chenghui Zhang;Xiangyang Xing;Alian Chen;
      Pages: 7492 - 7505
      Abstract: This article presents a fault-tolerant control strategy when an open-circuit fault (OCF) occurs in T-type three-level rectifiers, in which the neutral-point (NP) voltage balance and loss reduction are considered simultaneously. When an OCF occurs, one fundamental period is classified into two time intervals: the normal time interval (NTI), and abnormal time interval (ATI). In the NTI, a time-offset is utilized to achieve the NP voltage balance and loss reduction within a switching period. Aside from this, the extra switching event between the switching periods is also reduced by employing an appropriate carrier. In the ATI, the proposed method is explained by dividing fault into two conditions: the faulty condition of half-bridge switches, and NP switches. When OCF occurs at HB switches, a restriction of the time-offset is introduced during the ATI. While, if an OCF occurs at NP switches, the two-level modulation strategy is applied in the faulty phase during the ATI. Besides, the principle of carrier selection of the faulty phase is changed correspondingly to avoid the extra switching event. The performance of the fault-tolerant control with respect to the NP voltage balance and loss reduction is illustrated and verified by the simulation and experimental results.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Securing Full-Power-Range Zero-Voltage Switching in Both Steady-State and
           Transient Operations for a Dual-Active-Bridge-Based Bidirectional Electric
           Vehicle Charger
    • Authors: Yu Yan;Hua Bai;Andrew Foote;Wanbao Wang;
      Pages: 7506 - 7519
      Abstract: Dual-active-bridge (DAB) circuit is an excellent candidate for a high-efficiency, high-power density, and bidirectional electric vehicle charger. Unlike resonant circuits employing auxiliary inductors and capacitors, DAB minimizes the usage of passive components. The challenge, however, lies in the difficulty of securing zero-voltage switching (ZVS), particularly at light-to-medium load when using the conventional single-phase-shift (SPS) control. This is of utmost importance not only for the sake of the efficiency, but also for minimizing the switch-bridge crosstalk caused by the hard switching-on, thereby enhancing the system reliability. Although dual-phase-shift (DPS) and triple-phase-shift (TPS) can be the answer, they do introduce side effects such as larger switching-off current. This article systematically integrates SPS, DPS, and TPS to maximize full-power ZVS range for both steady state and transient operations in EV chargers. This article plots ZVS boundaries over the full power range, categorizes all operations into nine modes, and proposes a smooth transition method among all operation modes. Dead band is also incorporated in the ZVS boundary setting. Experimental results on a SiC-based charger validate the effectiveness of this method of widening ZVS range for output voltage of 200–450 Vdc and power of 0–20 kW, achieving smooth transitions among various operation modes, and suppressing the switch crosstalk, thereby securing high charger reliability.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Long-Horizon Finite-Control-Set Model Predictive Control With Nonrecursive
           Sphere Decoding on an FPGA
    • Authors: Tinus Dorfling;Hendrik du Toit Mouton;Tobias Geyer;Petros Karamanakos;
      Pages: 7520 - 7531
      Abstract: Long-horizon finite-control-set model predictive control is implemented on a field-programmable gate array (FPGA). To solve the underlying least-squares integer program, a nonrecursive sphere decoding algorithm is developed. By exploiting the problem structure, few multipliers are required, and the algorithm computes the optimal solution in a few clock cycles, thus achieving a resource-efficient implementation on the FPGA. For a prediction horizon of five steps and a three-level converter, 87 digital signal processor blocks, and an execution time of at most $text{13.4};mu text{s}$ was required to solve the optimization problem during steady-state operation. Experimental results verify the effectiveness of the long-horizon controller.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Novel Analytical Method for Dynamic Design of Renewable SSG SPC Unit to
           Mitigate Low-Frequency Electromechanical Oscillations
    • Authors: Mostafa Abdollahi;Jose Ignacio Candela;Joan Rocabert;Mohamed Atef Elsaharty;Pedro Rodriguez;
      Pages: 7532 - 7544
      Abstract: Grid operators require grid-connected renewable generation units (RGUs) to provide specific dynamic features. Among those features, the RGUs must support the dynamic performance of the power grid as well as operate in such a way to ward off new issues in the power system. Recently, unfavorable oscillatory modes have appeared through the grid connection of RGUs due to their dynamic interaction with other classical components of the grid. Therefore, it is essential to develop a novel technique for the dynamic design of RGUs to mitigate such risky oscillations. In this article, a novel analytical method is proposed for dynamic tuning of a renewable static synchronous generation unit controlled by synchronous power controller (RSSG-SPC). The proposed method is based on the mathematical analysis of the derivative function of general damping ratio formula. The analytical results establish generalized solutions that cover all operation mode of the RSSG-SPC. Further on, the solutions are implemented into the dynamic model of the RSSG-SPC to obtain clear, accurate, and trustable criteria for tuning of the virtual damping and virtual inertia. The dynamic tuning aims toward avoiding new oscillations in the system as well as to mitigate the natural oscillations of the power grid. The proposed approach was used for stability enhancement in high penetrated generation area as well as to support synchronization between interconnected areas in a two-area Kundur system. The proposed method was validated through modal analysis, time domain simulations as well as real-time evaluations which ensured that the proposed approach is a reliable technique for dynamic design of RSSG-SPCs.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A Single- and Three-Phase Grid Compatible Converter for Electric Vehicle
           On-Board Chargers
    • Authors: Hui Zhao;Yanfeng Shen;Wucheng Ying;Saikat Subhra Ghosh;Mohammad Rishad Ahmed;Teng Long;
      Pages: 7545 - 7562
      Abstract: This article proposes a voltage-source converter for an on-board electric vehicle charger, which is compatible with both the single- and three-phase (1-φ and 3-φ) grids. The classic 3-φ active ac–dc rectifier circuit is used for both the 1-φ and 3-φ connections, but a new control scheme and LCL filter are designed to address the double-line frequency power pulsation issue caused by a 1-φ grid without using bulky dc capacitors. The third leg of the circuit is utilized to control the power pulsation in conjunction with stored energy in the LCL filter between the grid and charger rectifier. Neither additional active nor passive components are required. For the 3-φ connection, the rectifier is under balanced operation; when connected with the 1-φ grid, all three legs are controlled cooperatively as a 3-φ rectifier but under unbalanced operation to recreate the 1-φ voltage. Hence, advantages from the 3-φ rectifier, such as space vector pulsewidth modulation and Y/Δ transformation, can be utilized to increase utilization of dc-link voltage and filter capacitance, respectively. The operation principle, control, and LCL filter design are reported and validated by both simulation and experiments of a 3-kW porotype.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Capacitor Voltage Fluctuation Minimization for Four-Level Hybrid Clamped
           Converter Using Improved Common-Mode Voltage Injection
    • Authors: Jianyu Pan;Yong Yang;Haiwei Cai;Longya Xu;
      Pages: 7563 - 7573
      Abstract: When a four-level hybrid clamped converter (4L-HCC) operates at low frequencies, the high load current causes significant voltage fluctuations among the capacitors in the dc link. A mathematical model is developed to clarify the mechanism of excessive capacitor voltage fluctuations. An improved common-mode voltage injection algorithm is proposed and integrated to the overall control method. With the applied algorithm, the voltage fluctuation minimization of the dc-link capacitors and the dynamic voltage balancing capability are investigated. Both simulation and experimental results validate the effectiveness of the proposed algorithm, with a voltage fluctuation reduction over 50%. The 4L-HCC with the proposed algorithm achieves much faster dynamic response to converge the unbalanced capacitor voltages and the reduced output current harmonics compared with the conventional common-mode voltage injection algorithm.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Distributed Screening of Hijacking Attacks in DC Microgrids
    • Authors: Subham Sahoo;Jimmy Chih-Hsien Peng;Sukumar Mishra;Tomislav Dragičević;
      Pages: 7574 - 7582
      Abstract: It is well-known that distributed control can improve the resiliency of dc microgrids against multiple link failures as compared to centralized control. However, the control layer is still vulnerable to cyber attacks. Unlike widely studied false data injection attacks, which involve adding false signals on top of the existing ones in the controller or communication links, hijacking attacks completely replace the existing signals. As a result, the compromised agent(s) diverge from steady state owing to imbalance in the iterative rule of consensus algorithm. To detect hijacking attacks, a novel distributed screening (DS) methodology is proposed. In addition to that, a fault detection (FD) metric is provided to assist the proposed attack detection strategy in differentiating between hijacking attacks and sensor faults. This reduces the complexity of decision making in the attack mitigation approach. Furthermore, interoperability of the proposed detection metrics allows simultaneous detection of sensor faults and hijacking attacks. The performance of the proposed detection metrics is evaluated under simulation and experimental conditions to conclude that it successfully detects the attacked agent(s) as well as sensor fault(s).
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Active-Damping Virtual Circuit Control for Grid-Tied Converters With
           Differential-Mode and Common-Mode Output Filters
    • Authors: Korawich Niyomsatian;Piet Vanassche;Johan J. C. Gyselinck;Ruth Vazquez Sabariego;
      Pages: 7583 - 7595
      Abstract: This article presents a virtual circuit control method of designing a resonant-damping discrete-time controller for grid-tied voltage source converters with differential-mode (DM) and common-mode (CM) output filters. The method provides an intuitive way to specify the desired closed-loop behavior by means of a virtual reference circuit rather than abstract mathematical criteria such as closed-loop poles and weighting matrices. Therefore, the existing passive filter designs, which cannot be practically implemented due to excessive losses, and the well-established theory of filters can be exploited. The DM grid current and the CM capacitor voltage, which are the primary control objectives, inherit the main properties of their underlying virtual reference circuits, e.g., resonance damping and low-frequency behavior. On this account, to fortify the controller against grid impedance variations, a virtual circuit with a series resistor at the grid side is considered. Accordingly, the CM voltage and DM current controllers can be easily designed based on the low-frequency behavior of virtual circuits. The method can also be straightforwardly equipped with conventional controllers to enhance system performance, such as harmonic compensation. The simulation and experimental results verify the effectiveness of the DM and CM resonant damping and dynamic performance.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • 1-kW Boost-type PFC Using a Low-Voltage Series Pass Module for Input
           Current Shaping
    • Authors: Chung-Pui Tung;John Wing-To Fan;Jeff Po-Wa Chow;Akhil Relekar;Wan-Tim Chan;Ka-Wai Ho;Ke-Wei Wang;Henry Shu-Hung Chung;
      Pages: 7596 - 7611
      Abstract: A power factor corrector extended from a previously proposed boost-type structure with power semiconductor filter (PSF) is presented. The concept of the PSF is based on using a series pass device (SPD) to profile the input current and regulate the output voltage, and an input capacitor to circulate the ripple current generated by the boost converter. However, the input capacitor is charged up slowly with small input current around the zero crossings, causing high voltage stress on the SPD. Then, a high-voltage device for the SPD is needed. However, high-voltage devices have large channel length modulation effect, high leakage current, large voltage drop, and slow response. To accelerate the capacitor charging and thus reduce the voltage stress, this article proposes to replace the output diode with a controllable switch. The converter is temporarily operated as a buck converter during the zero crossings with the input capacitor charged up swiftly by the output capacitor. The voltage across the SPD can be kept low over the line cycle, resulting in improved input current waveform and reduced power dissipation. A series pass module constructed by multiple parallel-connected low-voltage devices is used to increase current rating. The devices are regulated to operate around the knee point of the output characteristics to reduce power loss. A 1 kW, 85–265 Vac/400 Vdc prototype has been built and evaluated.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • DQ-Frame Zero-Crossing Effect Modeling and Current Distortion Compensation
           Method for Vienna Rectifier
    • Authors: Zheyu Miao;Hao Tong;Xiaoguang Jin;Wenxi Yao;Zhengyu Lu;Zhen Ma;
      Pages: 7612 - 7623
      Abstract: Vienna rectifiers are widely used as front-end rectifiers in many applications because of their high efficiency and high power density. However, this topology has a problem that its current is always distorted near zero-crossing points, especially when the converter-side current ripples are large. This article reveals and models the zero-crossing current distortion phenomenon, which is caused by nonshared vectors of adjacent sectors when the sector detection error occurs. Near the zero-crossing points, the inevitably sector detection errors will occur due to the presence of the switching current ripples and other factors such as the control delay. The errors can be divided into two types, namely, the lag error, and the lead error. The effects of the two types of errors are equivalently modeled in the dq frame in this article. When the detection error occurs, it is equivalent to applying additional interference terms to the control output. Based on the equivalent error model, this article proposes two compensation methods to eliminate the zero-crossing effect caused by the sector error. The proposed methods are effective and easy-to-implement. Finally, simulation and experimental results validate the theoretical analysis.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Review and Comparison of Grid-Tied Inverter Controllers in Microgrids
    • Authors: Qing Liu;Tommaso Caldognetto;Simone Buso;
      Pages: 7624 - 7639
      Abstract: Grid-tied inverters are widely used for interfacing renewable energy sources or storage devices to low-voltage electrical power distribution systems. Lately, a number of different control techniques have been proposed to address the emerging requirements of the smart power system scenario, in terms of both functionalities and performance. This article reviews the techniques proposed for the implementation of current-controlled or voltage-controlled inverters in microgrids. By referring to a voltage source inverter with an ${LCL}$ output filter, different control architectures are classified as single, double, and triple loop. Then, the functionalities that are needed or recommended in the grid-connected, islanded, and autonomous operating modes of the grid-tied inverter are identified and their implementation in the different control structures is discussed. To validate the analysis and to better illustrate the merits and limitations of the most effective solutions, six control strategies are finally implemented and experimentally compared on a single-phase, grid-connected inverter setup.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A Self-Organizing Global Sliding Mode Control and Its Application to
           Active Power Filter
    • Authors: Shixi Hou;Juntao Fei;
      Pages: 7640 - 7652
      Abstract: In this article, a self-organizing global sliding mode control (GSMC) is developed for a class of dynamic systems, whereby modeling uncertainties are estimated by metacognitive fuzzy-neural-network (MCFNN) framework. First, a GSMC is designed for the tracking of reference signals to eliminate the reaching mode and chattering phenomenon. To overcome the drawbacks of GSMC, the control law is designed based on MCFNN instead of the uncertain information. Distinguished from the fixed structure schemes, MCFNN can restructure the network structure and parameters by extracting useful input data not all data. Moreover, in order to alleviate redundant or inefficient computation, only the parameters of the rule nearest to the current data instead of all rules are updated online based on Lyapunov stability analysis. Finally, simulation and experimental investigations on active power filter are employed to verify the control performance of proposed controller.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Decentralized Quasi-Fixed-Frequency Control of Multiphase Interleaved
           Hybrid Dickson Converters for Fault-Tolerant Automotive Applications
    • Authors: Mojtaba Ashourloo;Venkata Raghuram Namburi;Gerard Villar Piqué;John Pigott;Henk Jan Bergveld;Alaa El Sherif;Olivier Trescases;
      Pages: 7653 - 7663
      Abstract: Emerging autonomous-driving systems necessitate a fault-tolerant power management system to ensure continuous power delivery to the safety processor and sensor loads, while the forthcoming 48-V bus system requires power conversion at high and wide-ranging input voltages. To address the challenges in future automotive applications, this article demonstrates a modular multiphase system with $N+1$ redundancy as the preregulator converter in a two-stage cascaded power conversion system. Each phase is implemented based on the 4-to-1 hybrid Dickson topology, which enables efficient high-ratio voltage conversion. This article proposes a new decentralized quasi-fixed-frequency control scheme based on the valley current mode and on-time control. In contrast to existing methods, the proposed scheme: 1) enables decentralized interleaving of the multiphase system using distributed phase-locked-loop-based synchronization in the event of a failure in any phase, which is advantageous in terms of modularity and scalability; 2) incorporates droop voltage control to achieve balanced current sharing and voltage regulation in a multiphase system; and 3) offers self-balancing of the flying-capacitor voltages, which eliminates the need for any additional control circuitry. The performance of the proposed scheme is verified using a 36-W four-phase experimental prototype.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • A Fast Estimation of Initial Rotor Position for Low-Speed Free-Running
           IPMSM
    • Authors: Ting Wu;Derong Luo;Sheng Huang;Xuan Wu;Kan Liu;Kaiyuan Lu;Xiaoyan Peng;
      Pages: 7664 - 7673
      Abstract: Fast and reliable initial rotor position detection is essential for restarting sensorless permanent magnet synchronous motors (PMSMs) in free-running condition. In this article, a fast initial rotor position estimation method for low-speed free-running motor is proposed, which utilizes a combined sinusoidal current and square-wave voltage injection method. The sinusoidal current is imposed into the estimated d-axis to magnify the magnetic saturation effect. The amplitudes of the d-axis current caused by injected square-wave voltage are then accumulated. The large difference of the two integrated signals for positive and negative d-axis currents can be reliably used to identify the rotor polarity. Meanwhile, in low-speed free-running stage, the change of saturation degrees introduced by the injected sinusoidal signal does not affect the position estimation accuracy. Moreover, even if the sinusoidal current signal is injected in the incorrect d-axis, the resultant torque is small and unexpected rotation of the rotor is prevented. Its influence on the free-running motor is negligible, due to the combined injection with continuously online updated estimated rotor position by high-frequency square-wave voltage injection during the polarity identification process. Finally, the effectiveness of the proposed method is investigated on a 1.5 kW interior PMSM test platform.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Modeling of Nine-Switch-Converter Based on Virtual Leg and Its Application
           in DFIG Wind Generation System
    • Authors: Kai Wang;Jingmei Zhang;Yi Pang;Dongxing Xu;Lei Pan;
      Pages: 7674 - 7688
      Abstract: This article proposes a doubly fed induction generator (DFIG) wind energy conversion system (WECS) based on nine-switch converter. In this article, a new concept of virtual-leg is proposed, and the equivalent mechanism between the nine-switch converter and the dual six-switch converter is first proposed. Furthermore, a mathematical model of the nine-switch converter based on the unipolar binary logic switching function is established. In order to simplify the mathematical model of the nine-switch-converter-based DFIG-WECS, the parameter mapping relationship between the nine-switch converter with loads and the nine-switch-converter-based DFIG-WECS under dq coordinate system is given. Meanwhile, the adaptive resonant proportional integral (PI) (AR-PI) current controller based on the resonant controller, the PI controller, and the adaptive genetic algorithm is applied for the DFIG wind generation system. As a result, harmonic current content, overshoot, and dynamic response speed of the nine-switch-converter-based DFIG-WECS have been significantly improved. Finally, the simulations and experimental results verify the validity and reliability of the proposed mathematical model and control algorithm.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Digital-Based Critical Conduction Mode Control for Three-Level Boost PFC
           Converter
    • Authors: Moonhyun Lee;Jong-Woo Kim;Jih-Sheng Lai;
      Pages: 7689 - 7701
      Abstract: Conventional critical conduction mode (CRM) control for many boost-derived power factor correction (PFC) circuits forms triangular inductor current. For three-level boost (TLB) converter, the conventional method is unattractive because losses increase but waveform quality remains unchanged, compared to other topologies. In order to obtain higher efficiency and improved waveform qualities, this article focuses on the distinctive structure of TLB and its inherent degree-of-freedom (DOF) in current-slope shaping. Based on the DOF, a new CRM control for TLB PFC is proposed and analyzed. Detailed design and digital implementation method are also provided. Different from conventional methods, the proposed CRM control divides each switching cycle into three parts including common on-time of two switches, additional on-time of one switch and common off-time. Accordingly, TLB inductor current is synthesized in quadrangular forms. The analyses and experimental results confirm that switching frequency and peak input current of TLB can be reduced by the proposed control. Due to the reductions, efficiency, total harmonic distortion, and quality of input current are improved with practically unchanged power factor.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
  • Unified SVPWM Algorithm and Optimization for Single-Phase Three-Level NPC
           Converters
    • Authors: Shunliang Wang;Junpeng Ma;Bi Liu;Ning Jiao;Tianqi Liu;Yanbo Wang;
      Pages: 7702 - 7712
      Abstract: The high-order harmonics caused by the modulation strategy can deteriorate power quality. The harmonic characteristics of the carrier-based pulsewidth modulation are relatively fixed and difficult to optimize, while space vector pulsewidth modulation (SVPWM) has more flexibility. The unified SVPWM design method for single-phase three-level neutral-point clamped (NPC) converters is fully presented in this article. Based on the proposed unified SVPWM method, two existing traditional vector sequences are designed first, and then several advanced multisegment SVPWM algorithms are proposed. According to the particularity of the three-level NPC topology, two hybrid SVPWM algorithms are proposed to optimize harmonic performance. Moreover, the high-order harmonic characteristics and the number of switching actions are analyzed in detail for all SVPWM algorithm modes. In addition, these SVPWM algorithms are associated and unified by introducing weight coefficients of the redundant vectors. Simulation and experimental results verify the feasibility and effectiveness of the proposed SVPWM algorithms, which show that the proposed methods can optimize high-order harmonic distribution and reduce the line current harmonics.
      PubDate: July 2020
      Issue No: Vol. 35, No. 7 (2020)
       
 
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