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  Subjects -> ELECTRONICS (Total: 194 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: 8)
Advances in Electronics     Open Access   (Followers: 94)
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  
Aerospace and Electronic Systems, IEEE Transactions on     Hybrid Journal   (Followers: 353)
American Journal of Electrical and Electronic Engineering     Open Access   (Followers: 27)
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: 14)
Australian Journal of Electrical and Electronics Engineering     Hybrid Journal  
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 8)
Batteries     Open Access   (Followers: 7)
Batteries & Supercaps     Hybrid Journal  
Bell Labs Technical Journal     Hybrid Journal   (Followers: 30)
Bioelectronics in Medicine     Hybrid Journal  
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 22)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 38)
Biomedical Instrumentation & Technology     Hybrid Journal   (Followers: 6)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 13)
BULLETIN of National Technical University of Ukraine. Series RADIOTECHNIQUE. RADIOAPPARATUS BUILDING     Open Access   (Followers: 1)
Bulletin of the Polish Academy of Sciences : Technical Sciences     Open Access   (Followers: 1)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 47)
China Communications     Full-text available via subscription   (Followers: 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: 301)
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: 104)
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  
Embedded Systems Letters, IEEE     Hybrid Journal   (Followers: 55)
Energy Harvesting and Systems     Hybrid Journal   (Followers: 4)
Energy Storage     Hybrid Journal  
Energy Storage Materials     Full-text available via subscription   (Followers: 3)
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)
Geoscience and Remote Sensing, IEEE Transactions on     Hybrid Journal   (Followers: 217)
Haptics, IEEE Transactions on     Hybrid Journal   (Followers: 4)
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 Journal of Emerging and Selected Topics in Power Electronics     Hybrid Journal   (Followers: 51)
IEEE Journal of the Electron Devices Society     Open Access   (Followers: 9)
IEEE Journal on Exploratory Solid-State Computational Devices and Circuits     Hybrid Journal   (Followers: 1)
IEEE Power Electronics Magazine     Full-text available via subscription   (Followers: 75)
IEEE Transactions on Antennas and Propagation     Full-text available via subscription   (Followers: 73)
IEEE Transactions on Automatic Control     Hybrid Journal   (Followers: 59)
IEEE Transactions on Circuits and Systems for Video Technology     Hybrid Journal   (Followers: 26)
IEEE Transactions on Consumer Electronics     Hybrid Journal   (Followers: 44)
IEEE Transactions on Electron Devices     Hybrid Journal   (Followers: 19)
IEEE Transactions on Information Theory     Hybrid Journal   (Followers: 26)
IEEE Transactions on Power Electronics     Hybrid Journal   (Followers: 78)
IEEE Transactions on Signal and Information Processing over Networks     Full-text available via subscription   (Followers: 13)
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  
IET Microwaves, Antennas & Propagation     Hybrid Journal   (Followers: 35)
IET Nanodielectrics     Open Access  
IET Power Electronics     Hybrid Journal   (Followers: 57)
IET Smart Grid     Open Access  
IET Wireless Sensor Systems     Hybrid Journal   (Followers: 18)
IETE Journal of Education     Open Access   (Followers: 4)
IETE Journal of Research     Open Access   (Followers: 11)
IETE Technical Review     Open Access   (Followers: 13)
IJEIS (Indonesian Journal of Electronics and Instrumentation Systems)     Open Access   (Followers: 3)
Industrial Electronics, IEEE Transactions on     Hybrid Journal   (Followers: 74)
Industrial Technology Research Journal Phranakhon Rajabhat University     Open Access  
Industry Applications, IEEE Transactions on     Hybrid Journal   (Followers: 38)
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: 36)
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 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  
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: 30)
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  
Learning Technologies, IEEE Transactions on     Hybrid Journal   (Followers: 12)
Magnetics Letters, IEEE     Hybrid Journal   (Followers: 7)
Majalah Ilmiah Teknologi Elektro : Journal of Electrical Technology     Open Access   (Followers: 2)
Metrology and Measurement Systems     Open Access   (Followers: 6)
Microelectronics and Solid State Electronics     Open Access   (Followers: 28)
Nanotechnology Magazine, IEEE     Full-text available via subscription   (Followers: 42)
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)
Optical Communications and Networking, IEEE/OSA Journal of     Full-text available via subscription   (Followers: 16)
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)
Pulse     Full-text available via subscription   (Followers: 5)
Radiophysics and Quantum Electronics     Hybrid Journal   (Followers: 2)
Recent Advances in Communications and Networking Technology     Hybrid Journal   (Followers: 4)
Recent Advances in Electrical & Electronic Engineering     Hybrid Journal   (Followers: 10)
Research & Reviews : Journal of Embedded System & Applications     Full-text available via subscription   (Followers: 5)
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)
Services Computing, IEEE Transactions on     Hybrid Journal   (Followers: 4)
Software Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 79)
Solid State Electronics Letters     Open Access  
Solid-State Circuits Magazine, IEEE     Hybrid Journal   (Followers: 13)
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)
Wireless Power Transfer     Full-text available via subscription   (Followers: 4)
Women in Engineering Magazine, IEEE     Full-text available via subscription   (Followers: 11)
Електротехніка і Електромеханіка     Open Access  

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Similar Journals
Journal Cover
IEEE Transactions on Power Electronics
Journal Prestige (SJR): 2.215
Citation Impact (citeScore): 9
Number of Followers: 78  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0885-8993
Published by IEEE Homepage  [191 journals]
  • IEEE Power Electronics Society
    • Abstract: Provides a listing of current staff, committee members and society officers.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • IEEE Power Electronics Society
    • Abstract: Provides a listing of current committee members and society officers.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Administrative Committee
    • Abstract: Provides a listing of current committee members and society officers.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A Load-Independent Wireless Power Transfer System With Multiple Constant
           Voltage Outputs
    • Authors: Chenwen Cheng;Weiguo Li;Zhe Zhou;Zhanfeng Deng;Chris Mi;
      Pages: 3328 - 3331
      Abstract: A novel wireless power transfer (WPT) system is proposed to power the gate drivers in a multilevel converter to achieve a high insulation level. There are two requirements for the proposed WPT system. First, the WPT system should contain multiple outputs, each corresponding to one gate driver. Second, a constant voltage source is needed for each gate driver. For a multiload WPT system, it is challenging but necessary to realize independent power control of each load. To achieve this goal, the repeater unit consisting of two repeater coils is designed to power a load. Many loads can be powered simultaneously by using multiple repeater units together. The LCC-S compensation topology is adopted for the proposed WPT system. Constant voltage outputs are obtained for all the loads when neglecting the coil's parasitic resistance. An experimental platform with six loads was developed to validate the proposed WPT system.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A Fast and Robust Real-Time Detection Algorithm of Decaying DC Transient
           and Harmonic Components in Three-Phase Systems
    • Authors: Liansong Xiong;Xiaokang Liu;Chengyong Zhao;Fang Zhuo;
      Pages: 3332 - 3336
      Abstract: Active power filters are conventionally utilized to compensate steady-state harmonic currents and reactive power in the utility, yet their capabilities are usually limited if the elimination of undesirable effects associated with decaying dc components during transients is the target, especially under the weak grid condition. In this letter, active cancellation of the typical first-order decaying dc-mode transients is explored. To this end, a real-time detection algorithm of decaying dc component is first developed for a generic single-phase distorted ac signal. Furthermore, fast and robust elimination of both decaying dc transient and harmonics can be performed simultaneously in three-phase grids, by adoption of moving average filters in $d$–$q$ frame and subsequent calculations. Hardware-in-the-loop experiment results verified the effectiveness of the proposed technique.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • High-Precision Control for ZVS Inverter to Reduce Nonlinear Distortion of
           Semiconductor Voltage Drop
    • Authors: Hailin Zhang;Jun Yao;Baoquan Kou;Jian Wei;
      Pages: 3337 - 3342
      Abstract: Owing to low switching loss and low dead-time effect, the extra-LC auxiliary resonant snubber converter as a zero-voltage-switching inverter is very suitable for high-precision applications. However, the semiconductor voltage drop caused by the on-resistance is one of the main problems in the high-precision application, which has not been researched before. Besides, the conventional forward compensation method leads to obvious error due to the nonlinear characteristic of on-resistance. Thus, this letter proposed a high-precision control through controlling the auxiliary circuit current to reduce the nonlinear distortion caused by the semiconductor voltage drop. Compared with the forward compensation method, the on-resistance of the switches is not required to be estimated. In this letter, the voltage error caused by the on-resistance is analyzed. The proposed high-precision control is introduced. The experimental results demonstrate that the quality of the output current and voltage is improved by utilizing the proposed control method.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Online Frequency Response Measurements of Grid-Connected Systems in
           Presence of Grid Harmonics and Unbalance
    • Authors: Roni Luhtala;Henrik Alenius;Tuomas Messo;Tomi Roinila;
      Pages: 3343 - 3347
      Abstract: Grid characteristics have a drastic impact on the stability and control performance of grid-connected systems. Because the grid conditions typically vary over time, online measurements are most desirable for the stability assessment, protection design, and control system optimization of the systems. Previous studies have presented methods based on Fourier techniques and broadband sequences, with which the frequency responses of the grid-connected systems, such as the grid impedance or inverter control loops, can be measured. However, online measurements under unbalanced grids with harmonic voltages have not been comprehensively considered. This letter demonstrates how the previously applied online measurement methods fail in the presence of unbalanced grid and voltage harmonics due to the spectral leakage caused by the Fourier transform. This letter also proposes a simple signal design method to avoid the leakage. Experimental results based on a high-power grid-connected system are shown to demonstrate the effectiveness of the proposed method.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Study on DFIG Dissipation Energy Model and Low-Frequency Oscillation
           Mechanism Considering the Effect of PLL
    • Authors: Yaqi Shen;Jing Ma;Letian Wang;A. G. Phadke;
      Pages: 3348 - 3364
      Abstract: Considering the dynamic characteristics of phase-locked loop (PLL), the effect of interaction between doubly fed induction generator (DFIG) and power grid on system low-frequency oscillation is revealed from the perspective of dissipation energy. First, the dynamic energy model of DFIG with PLL is derived, and the component that varies nonperiodically is extracted and defined as the dissipation energy. Second, the dissipation energy is decomposed into the free dissipation energy and DFIG-grid coupled dissipation energy. On this basis, the free dissipation intensity and coupled dissipation intensity are defined, which, respectively, characterize the immanent damping of DFIG and the DFIG-grid interaction degree. Thus, the contribution degree of DFIG to electromechanical oscillation is quantified for evaluation, and the mechanism of interaction between DFIG and power grid is further revealed. Finally, hardware-in-the-loop simulation tests with real-time digital simulator of the IEEE 10-machine 39-bus system verify that when the oscillation frequency of PLL is close to electromechanical oscillation frequency, strong coupling and resonance exist between DFIG and grid, and negative dissipation effect on the oscillation of DFIG will result. Thus, DFIG, as an oscillator, continuously injects dynamic energy to the grid, causing the system to oscillate to instability.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A Novel Single-Phase Three-Level Dual-Buck Inverter
    • Authors: Tien-The Nguyen;Honnyong Cha;Bang Le-Huy Nguyen;Heung-Geun Kim;
      Pages: 3365 - 3376
      Abstract: This article proposes a new single-phase three-level dual-buck inverter. The topology is derived from a simplified neutral-point clamped inverter that includes fewer active switches. The advantages of the proposed inverter are no shoot-through worries and no reverse recovery issue of the body diode of the power metal-oxide-semiconductor field-effect transistor compared with the conventional inverter; therefore, a high-reliability inverter can be achieved. The operation modes and pulsewidth modulation technique are analyzed in detail. Additionally, a switching scheme is proposed to balance and reduce the direct-current-link capacitance. A 1.4-kW prototype was built and tested to validate the theoretical analysis of the proposed converter.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A Hybrid Modular DC/DC Converter for HVDC Applications
    • Authors: Binbin Li;Xiaodong Zhao;Shuxin Zhang;Qintian Fu;Shengbo Wang;Dianguo Xu;
      Pages: 3377 - 3389
      Abstract: Recently, remarkable progress has been made in the voltage-source-converter-based high-voltage direct current (HVdc) transmissions. For the upcoming need to interconnect multiple dc transmission lines with different voltage levels, high-voltage and large power dc/dc converters are necessary. This article investigates a nonisolated bidirectional dc/dc converter that is composed by cascaded half-bridge submodules, series-connected diodes, and mechanical disconnectors. This hybrid topology presents very attractive features, such as low cost, high efficiency, and light weight. Operation principle, parameter design, and dedicated control strategies are developed. Simulation of a 150-MW, 200 kV/300 kV dc/dc converter has been performed to verify its performance and evaluate the efficiency. Moreover, a downscaled three-phase prototype rated at 500 V/300 V 4.5 kW has been built and tested. The experimental results further confirm the effectiveness of the proposed dc/dc converter.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Space Vector Modulation for SiC and Si Hybrid ANPC Converter in
           Medium-Voltage High-Speed Drive System
    • Authors: Chushan Li;Rui Lu;Chengmin Li;Wuhua Li;Xiaowei Gu;Youtong Fang;Hao Ma;Xiangning He;
      Pages: 3390 - 3401
      Abstract: Medium-voltage high-speed drive is promising in applications, such as the centrifugal compressors and electrified transportation. However, it raises lots of design challenges for the converters, which drive the motors. A SiC and Si hybrid ANPC converter is developed to address these challenges. In this article, the essence of this hybrid structure is investigated to clearly show the derivation process of the hybrid active neutral-point-clamped (ANPC) converter and inspire future research on these hybrid topologies. A dedicated space vector modulation (SVM) scheme is proposed for the hybrid ANPC converter, which enables the three-phase hybrid ANPC converter operating with SiC mosfets in high frequency and Si IGBTs in fundamental frequency. A neutral point (NP) voltage balancing scheme is added to the SVM scheme to balance the NP voltage imbalance under low-frequency modulation index. All these efforts make the hybrid ANPC converter become a high power density and fairly low-cost solution. A 400 Hz fundamental frequency, 3.6 kHz switching frequency, medium-voltage high-speed drive system is assumed and tested by the scaled-down experimental results. The effectiveness of the proposed SVM and NP voltage balancing method have both been verified.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Trapezoidal Current Modulation for Bidirectional High-Step-Ratio Modular
           DC–DC Converters
    • Authors: Yang Qiao;Xiaotian Zhang;Xin Xiang;Xu Yang;Timothy C. Green;
      Pages: 3402 - 3415
      Abstract: A modular dc–dc converter (MDCC) has been proposed for high-step-ratio interconnection in dc grid applications. To further optimize the performance of the MDCC, this article presents a trapezoidal current modulation with bidirectional power flow ability. By giving all the submodule (SM) capacitors an equal duty to withstand the stack dc voltage, their voltages are balanced without additional feedback control. Moreover, based on soft-switching performance and circulating current analysis, three-level and two-level operation modes featured with high efficiency conversion and large power transmission, respectively, are introduced. The control schemes of both modes are designed to minimize the conduction losses. Besides, the SM capacitor voltage ripples with different switching patterns are compared, and the option for ripple minimization is presented. A full-scale case study is provided to introduce the design process and device selection of the MDCC. The experimental tests based on a downscaled prototype are finally presented to validate the theoretical analysis.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Operational Analyses and Control Scheme of Nine-Arm Modular Multilevel
           Converter
    • Authors: Futian Qin;Feng Gao;Chenghui Zhang;
      Pages: 3416 - 3433
      Abstract: Nine-arm modular multilevel converter (9A-MMC) can be applied in many medium-/high-voltage applications with two sets of three-phase terminals, such as medium-voltage dual-motor drives and unified power flow controller, to replace two conventional modular multilevel converters for reducing the volume and cost. This article thoroughly investigated the operational principle of 9A-MMC, and proposed a unique operational mode that the number of submodules in each arm can be a variable. The mathematical model of 9A-MMC and steady-state analyses of capacitor voltage fluctuations and circulating current were studied in this article as well. Subsequently, a complete control scheme of 9A-MMC, including capacitor voltage balancing control and circulating current suppression control is systematically presented. Finally, the simulation and experimental results verified the performance of 9A-MMC and the effectiveness of the presented control methods.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A Hybrid Modular DC Solid-State Transformer Combining High Efficiency and
           Control Flexibility
    • Authors: Yuwei Sun;Zhen Gao;Chao Fu;Chengjie Wu;Zhe Chen;
      Pages: 3434 - 3449
      Abstract: This article presents a hybrid modular dc solid-state transformer (HMDCSST) composed of a series resonant dual active bridge (SR-DAB) and a phase-shift dual active bridge (PS-DAB), aiming at improving the transfer efficiency as well as maintaining the control flexibility key problems in terms of modeling and control strategy are discussed in this article. The generalized average and small-signal models of the HMDCSST are derived and confirmed by simulation, in which two LC filters are also considered to reduce the ripple components of the input and output currents. Based on the models, the control strategies to achieve the flexible control of the output voltage and power are designed. Moreover, as a key problem for HMDCSST, the design principle of the number for each type of DAB is discussed to meet the demands of the grid. Finally, a three-module prototype of HMDCSST consisting of one PS-DAB and two SR-DAB modules was built-up and tested, and the results proved that HMDCSST has higher efficiency than the traditional DCSST based on PS-DABs purely, without sacrificing the output voltage and power regulating capability in the meanwhile.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A 2-kV Charge-Based ZVS Three-Level Inverter
    • Authors: Sjef J. Settels;Jorge L. Duarte;Jeroen van Duivenbode;Elena A. Lomonova;
      Pages: 3450 - 3465
      Abstract: Industrial applications, e.g., semiconductor manufacturing equipment, require power converters providing high power with high precision and bandwidth. This article presents a three-level flying capacitor resonant pole inverter configuration that combines high output power and high switching frequency with reduced switch voltage stress. A multilevel modulation strategy is applied to minimize conduction losses, which, in addition, guarantees zero-voltage switching (ZVS) for the entire operating range to reduce switching losses. The proposed multilevel converter configuration is compared with an existing two-level configuration by simulation. Increasing the number of voltage levels results in lower total losses and increased linearity of the generated output current. Experimental results acquired with a hardware prototype validate the fast switching of high voltage, proper functioning of the multilevel modulation strategy, and achieving of ZVS. Improvements of the theoretical analysis are presented to compensate for delays in the system and deviating parameter values. Results obtained with a compensated system indicate a relatively high accuracy and linearity of the generated output current of the inverter.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Symmetric Sensing Coil Design for the Blind-Zone Free Metal Object
           Detection of a Stationary Wireless Electric Vehicles Charger
    • Authors: Van X. Thai;Gi C. Jang;Seog Y. Jeong;Jun H. Park;Yun-Su Kim;Chun T. Rim;
      Pages: 3466 - 3477
      Abstract: In this article, a simple and cost-effective symmetric sensing coil set to be used for the metal object detection (MOD) in a stationary wireless electric vehicle charger is newly proposed. Compared to the conventional nonoverlapping sensing coil using the magnetic field change detection method, the proposed symmetric sensing coil set design offers the considerable advantage of eliminating all blind zones, i.e., regions where metal is undetectable in the conventional method. Moreover, by reducing the number of layers to one, the fabrication of the proposed sensing coil is easier and more cost effective. The design of the proposed sensing coil is optimized for highly sensitive MOD based on a sensitivity equation and on the finite element method simulations. An experiment conducted with a metal object 40 × 40 mm2 in size and a 20 A transmitting (Tx) coil current verifies the reliability and the blind-zone elimination feature of the proposed sensing coil.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Evaluation of DC-Link Voltage Switching Ripple in Multiphase PWM Voltage
           Source Inverters
    • Authors: Marija Vujacic;Obrad Dordevic;Gabriele Grandi;
      Pages: 3478 - 3490
      Abstract: This article presents a generalized approach toward the dc-link voltage switching ripple analysis in the two-level multiphase pulsewidth modulation (PWM) voltage source inverters with a balanced load. Since the voltage ripple is one of the crucial sizing criteria for a dc-link capacitor, a simple and practical equation for designing the dc-link capacitor, based on the maximum (peak-to-peak) value of the dc-link voltage ripple, has been proposed for the multiphase inverters. The amplitude of the dc-link voltage switching ripple is analytically derived as a function of operating conditions. The effect of the number of phases on the dc-link capacitor size is investigated as well. It is found that considering the same total output current, the dc-link capacitor size is reduced by increasing the number of phases up to seven. However, from the point of view of the dc-link capacitor size, there are no benefits of further increasing the number of phases. Reference is made to two commonly used modulation strategies—sinusoidal PWM and continuous symmetric centered PWM (i.e., space vector). The mathematical models are derived with an aim to provide the precise dc-link capacitor sizing and hence improve the power density of the whole system. The comparison of different phase numbers has been made. Proposed theoretical developments are verified by the simulation and experimental tests.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Design-Oriented Comprehensive Time-Domain Model for CLLC Class Isolated
           Bidirectional DC-DC Converter for Various Operation Modes
    • Authors: Jianning Sun;Liqiang Yuan;Qing Gu;Renzhi Duan;Zixian Lu;Zhengming Zhao;
      Pages: 3491 - 3505
      Abstract: A comprehensive time-domain model of a CLLC class isolated bidirectional dc–dc converter (IBDC) is proposed in this article. Based on the circuit analysis and the solution of the state equations, analytical expressions of the state variables are provided. The model is a piecewise time-domain analytical model and can accurately describe the transformer currents and capacitor voltages under almost all basic types of control strategies, e.g., phase-shift control and frequency modulation control. With the model, the steady-state analysis of the IBDC can speed up evidently (up to 330 times faster compared to MATLAB/Simulink and more than 10 times compared to SIMPLIS and PLECS), which gives great support to parameter sweep and case comparison in the design procedure. By assigning specific parameters, the presented model can also be applied to the analysis of the LLC resonant IBDC or typical DAB IBDC since the LLC converter and DAB converter are similar to the CLLC converter in the circuit topology. The transformation of the model from CLLC to LLC/DAB is provided and several application examples are given. Finally, the simulation and experimental results are presented, verifying the effectiveness of the model.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A Simplified 3-D NLM-Based SVPWM Technique With Voltage-Balancing
           Capability for 3LNPC Cascaded Multilevel Converter
    • Authors: Hongjian Lin;Zeliang Shu;Jiaxuan Yao;Han Yan;Leilei Zhu;Deng Luo;Xiaoqiong He;
      Pages: 3506 - 3518
      Abstract: The nearest level modulation (NLM)-based space vector pulsewidth modulation (SVPWM) algorithms have attracted a great deal of interest since they can provide various degrees of freedom, i.e., optimized switching sequences and adjustable duty cycles. This article proposes a simplified three-dimensional (3-D) NLM-based SVPWM algorithm in a 3-D coordinate system. Compared with the generalized two-dimensional (2-D) NLM-based SVPWM schemes, the proposed method not only provides identical degrees of freedom to optimize switching patterns and obtain adjustable duty cycles, but also presents better digital implementation and lower hardware occupancy to achieve the real-time PWM generation. In addition, based on the NLM-based principle, a method of addressing the issue of unbalanced voltages in a three-phase 3-level neutral point clamped cascaded multilevel converter (3LNPC-CMC) is introduced. The presented method possesses the optimized voltage-balancing capacity and equalizes the unbalanced inner cell and mutual cell voltages in the 3LNPC-CMC with minimum number switching transition. Finally, the whole proposed process is verified by simulation and experimental results.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Two-Port Network Modeling and Stability Analysis of Grid-Connected
           Current-Controlled VSCs
    • Authors: Shih-Feng Chou;Xiongfei Wang;Frede Blaabjerg;
      Pages: 3519 - 3529
      Abstract: Converter–grid interactions tend to bring in frequency-coupled oscillations that deteriorate the grid stability and power quality. The frequency-coupled oscillations are generally characterized by means of multiple-input multiple-output (MIMO) impedance models, which requires using the multivariable control theory to analyze resonances. In this article, instead of the MIMO modeling and analysis, the two-port network theory is employed to integrate the MIMO impedance models into a single-input single-output (SISO) open-loop gain, which is composed by a ratio of two SISO impedances. Thus, the system resonance frequency can be readily identified with Bode plots and the classical Nyquist stability criterion. Case studies in both simulations and experimental tests corroborate the theoretical stability analysis.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Composite DC Power Flow Controller
    • Authors: Xu Zhong;Miao Zhu;Yongning Chi;Siqi Liu;Xu Cai;
      Pages: 3530 - 3542
      Abstract: The utilization of a dc power flow controller in multiterminal HVDC (MTDC) can increase the control dimension of dc power flow, by which both the active power distribution capability and coordination control performance can be enhanced in MTDC. In this article, a novel concept of “composite dc power flow controller (CDCPFC)” has been proposed, and the general construction principles of technical frame have been given for function description. A specific CDCPFC topology has been implemented, which is featured with a straightforward dc–dc power conversion path via a transformerless structure. The operation principle, circuit characteristics, and control strategy of the proposed CDCPFC are analyzed in detail. Both simulation and experimental results proved that the proposed topology could realize power flow control function of two individual lines under various conditions with a good application prospect.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Design of a Protection Concept for a 100-kVA Hybrid Transformer
    • Authors: Johannes Burkard;Jürgen Biela;
      Pages: 3543 - 3557
      Abstract: Due to the increasing integration of renewable energies into the distribution grid, a deterioration of the grid power quality is expected. Consisting of a low-frequency transformer and a fractionally rated power electronic converter, hybrid transformers (HTs) can be applied to ensure a high power quality by controlling voltage, active and reactive power dynamically. For the application in conventional grids, HTs have to withstand considerable overvoltages and overcurrents during voltage surges or short circuits. Although HTs recently gained increasing research interest, protection requirements and protection concepts have not been discussed yet. These aspects are, however, essential to evaluate the practical potential of HTs. In this article, protection requirements are derived and a protection concept is developed and verified by simulations and experiments for a 100-kVA hybrid distribution transformer. Although the protection concept has a considerable impact on the design and performance of the converter, it increases the total losses and volume of the HT only insignificantly. An efficiency of 98.48% is achievable for an HT including protection, which is only slightly lower than the efficiency of 98.64% for a comparable conventional transformer. This renders the HT a promising solution for today's and future ac grids.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • All-Pass-Filter-Based PLL Systems: Linear Modeling, Analysis, and
           Comparative Evaluation
    • Authors: Saeed Golestan;Josep M. Guerrero;Juan C. Vasquez;Abdullah M. Abusorrah;Yusuf Al-Turki;
      Pages: 3558 - 3572
      Abstract: All-pass filter (APF) passes all frequency components of a signal without altering their amplitude, but changes their phase. This feature has made the APF a versatile building block in different signal processing applications. The focus of this article is on APF-based phase-locked loops (PLLs), where the APF is required for creating a $text{90}^circ$ phase shift at the fundamental frequency. Such a phase shift is needed for generating a fictitious orthogonal signal in single-phase applications and rejecting the grid voltage imbalance in three-phase systems. To the best of authors’ knowledge, none of the APF-based PLLs have an accurate model yet. This gap in knowledge makes the analysis of these synchronization systems and identifying their advantages/disadvantages compared to state-of-the-art structures complicated. The main objective of this article is to bridge this knowledge gap.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Design-Oriented Transient Stability Analysis of PLL-Synchronized
           Voltage-Source Converters
    • Authors: Heng Wu;Xiongfei Wang;
      Pages: 3573 - 3589
      Abstract: Differing from synchronous generators, there are lack of physical laws governing the synchronization dynamics of voltage-source converters (VSCs). The widely used phase-locked loop (PLL) plays a critical role in maintaining the synchronism of current-controlled VSCs, whose dynamics are highly affected by the power exchange between VSCs and the grid. This article presents a design-oriented analysis on the transient stability of PLL-synchronized VSCs, i.e., the synchronization stability of VSCs under large disturbances, by employing the phase portrait approach. Insights into the stabilizing effects of the first- and second-order PLLs are provided with the quantitative analysis. It is revealed that simply increasing the damping ratio of the second-order PLL may fail to stabilize VSCs during severe grid faults, whereas the first-order PLL can always guarantee the transient stability of VSCs when equilibrium operation points exist. An adaptive PLL that switches between the second-order and the first-order PLL during the fault-occurring/-clearing transient is proposed for preserving both the transient stability and the phase-tracking accuracy. Time-domain simulations and experimental tests, considering both the grid fault and the fault recovery, are performed, and the obtained results validate the theoretical findings.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A New Soft-Switched Three-Port DC/DC Converter With High Voltage Gain and
           Reduced Number of Semiconductors for Hybrid Energy Applications
    • Authors: Sina Salehi Dobakhshari;Seyyed Hamid Fathi;Jafar Milimonfared;
      Pages: 3590 - 3600
      Abstract: A new partly isolated three-port converter is introduced in this study for hybrid energy applications. Two boost circuits form the main input port and a bidirectional battery port of the converter. Therefore, both of them are of a current-fed type, making the converter more suitable for renewable energy applications. In addition, the boost circuits are benefited from a mutual active clamp circuit. The circuit in cooperation with the leakage inductance of transformers provides soft switching, while employing a few number of semiconductors. Furthermore, on the secondary side, two voltage-doubler rectifiers are merged. As a result, the converter employs less number of components, which participate in all power conversion modes. Since most of the renewable energy sources have a relatively low voltage level, the converter retains high voltage gain. These features have resulted in an efficient and inexpensive converter. A thorough analysis has been made and justified by simulation and experimental results.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A Single-Stage Soft-Switched Isolated Three-Phase DC–AC Converter
           With Three-Phase Unfolder
    • Authors: Anirban Pal;Kaushik Basu;
      Pages: 3601 - 3615
      Abstract: This article proposes a unidirectional, single-stage, three-phase, and high-frequency-link dc–ac converter. The converter uses three high-frequency transformers to provide galvanic isolation. In the primary, the converter has three half-bridge legs. In the secondary, three diode-bridge rectifiers are used. Each rectifier is followed by a half-bridge (unfolder) leg. The modulation strategy proposed in this article ensures zero-voltage switching of all six primary side switches over the entire line cycle without additional snubber circuit. The secondary half-bridge legs are switched at line frequency, incurring negligible switching loss. The proposed converter does not require any interstage bulky dc-link filter capacitor. Thus, the overall filtering requirement is reduced, and the converter reliability is improved. The high-frequency galvanic isolation improves the converter power density. In this article, the modulation strategy and converter operation are described in detail. The operation is validated in a 3.7-kW hardware prototype. Key experimental results are presented in this article.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Second-Harmonic Ripple Voltage Suppression of Integrated Single-Phase
           Pulsewidth Modulation Rectifier Charging System for EVs
    • Authors: Yun Zhang;Jian Fang;Fei Gao;Tianbao Song;Shenghan Gao;Daniel J. Rogers;
      Pages: 3616 - 3626
      Abstract: In single-phase ac battery chargers, pulsating power at twice of the line frequency is delivered by the ac source resulting in second-harmonic ripple voltage on the dc-link if additional passive or active filter (AF) circuits are not used. In this article, an inductance-based AF using the leakage inductance of the machine windings along with a current compensation control method is proposed. No additional passive components are required. The machine used in this article has a double-layer winding with a center tap in each phase and the winding structure of the machine is special in that the pulsating magnetomotive force of the whole phase winding can be cancelled when currents flow into the central tap. In this article, the operating principle and control strategy of the AF with the inductive energy storage are analyzed. Finally, a 400-W experimental prototype is developed and the experimental results are used to validate the performance and feasibility of the proposed converter and control strategy.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A Magnetic Core Permeance Model for Inductive Power Harvesting
    • Authors: Martin J. Vos;
      Pages: 3627 - 3635
      Abstract: A current transformer (CT) is a preferred device to harvest power in the high-voltage utility grid to power monitoring equipment. Widespread CT use is foreseen in future smart grid deployment. The most common CT use involves a laminated transformer iron split core installation around a high-voltage cable with a particular number of turns to power a load or burden. Less common is a gapless core installation to improve reliability and prevent CT degradation by avoiding gap corrosion. Even laminated high resistivity cores still suffer from eddy current loss. The goal is to design a core able to deliver the desired power at optimum number of turns, minimized dimensions, and minimal loss. This article focuses on the core permeance as a complex parameter, on core size, losses or efficiency, load impedance optimization, flux level, power factor performance, and the relationship between these parameters. A similar size split core shows reduced loss compared to a gapless core. Lossy cores can still operate relatively efficiently at low flux levels indicating that the load current should preferably approach the short circuit current. Notwithstanding nanocrystalline and ferrite material advantages, silicon-doped laminated iron remains the preferred choice for 50/60 Hz inductive power harvesting.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Highly Efficient Bidirectional Series-Resonant DC/DC Converter Over Wide
           Range of Battery Voltages
    • Authors: Changkyu Bai;Byeongcheol Han;Bong-Hwan Kwon;Minsung Kim;
      Pages: 3636 - 3650
      Abstract: This article introduces a highly efficient bidirectional resonant dc/dc converter over wide range of battery voltages for vehicle-to-grid (V2G) capable electric vehicles (EVs). It operates as a pulsewidth-modulation (PWM) full-bridge series-resonant converter in the forward direction and a half-bridge resonant boost converter in the backward direction. One advantage of the proposed converter is that it has a wide voltage gain range in the backward operation. Also, it requires only six active switches. To achieve high efficiency, SiC mosfets are used for two bottom switches in the primary side, because only these switches suffer hard switching turn-off in both forward and backward directions. Since it operates with fixed-frequency and with PWM control, the magnetic components and passive filters can be optimally designed with respect to the volume and the loss. Thus, the proposed converter achieves low-cost, high-conversion ratio, and high efficiency over a wide range of battery voltages. Detailed analysis of the converter operation is presented along with the design procedure. A 3.3-kW/400-V prototype of the proposed converter has been built to operate for 250–415 V primary source voltages and tested to demonstrate its circuit design.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Open-Phase Fault-Tolerant Operation of the Three-Phase Dual Active Bridge
           Converter
    • Authors: Maxime Berger;Ilhan Kocar;Handy Fortin-Blanchette;Carl Lavertu;
      Pages: 3651 - 3662
      Abstract: The three-phase dual active bridge (3p-DAB) converter is widely considered in dc-grid applications. Because of the higher number of switches in the 3p-DAB, it can be argued that the reliability of the 3p-DAB is reduced when compared to other isolated-bidirectional dc–dc converter topologies. The previous work has shown that the 3p-DAB can be operated in a frozen leg fault-tolerant mode, i.e., with the two transistors of the same phase being opened by their gate driver internal protections. Because the free-wheeling diodes are left self-commutated, the analytical characterization of the converter for all voltage and loading conditions is not trivial. In this article, it is proposed to open the faulty phase such as it eliminates the interaction with the faulty-phase free-wheeling diodes. This allows the converter to fall in a characterizable operating mode for all voltage and loading conditions. The results further show that the open-phase operation provides advantages over the frozen leg operation in terms of current stress and power transfer capability. Experimental results on a small-scale closed-loop gallium nitride-based prototype as well as time-domain simulation results are provided to support the theoretical analyses.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • An SSHI Rectifier for Triboelectric Energy Harvesting
    • Authors: Xian Li;Ye Sun;
      Pages: 3663 - 3678
      Abstract: In this article, a synchronized switching harvesting on inductor (SSHI)-based rectifier for triboelectric energy harvesting is reported for the first time. In the recent few years, triboelectric energy harvesters (TEs), also called triboelectric nanogenerators (TENGs), are emerging and extensively studied, which provide promising solutions for converting mechanical energy to electricity as power resources for electronics. To practically power electronics from TENGs, a power management module with high energy efficiency is also essential. The state of the art of power management circuits for triboelectric energy harvesting is mainly focused on increasing dc–dc power efficiency technically. In this article, we report an SSHI rectifying strategy associated with TEH design and provide a new perspective on designing TEHs or TENGs by considering their capacitance concurrently. A new theoretical model is developed for electricity generation from triboelectric energy harvesting considering the introduced pairing capacitance and the impact force under practical condition. We also demonstrate that ultralow-cost, easy-fabricated TEHs can also generate a reasonable amount of power. The experimental results show that the proposed SSHI rectifier increases the harvested power by 242.83% when compared with a full-wave bridge rectifier for a newly designed low-cost TEH. The proposed SSHI interface provides a promising strategy of rectifier design to enhance ac–dc energy efficiency for triboelectric energy harvesting.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Coat Circuits for DC–DC Converters to Improve Voltage Conversion
           Ratio
    • Authors: Binxin Zhu;Feng Ding;Don Mahinda Vilathgamuwa;
      Pages: 3679 - 3687
      Abstract: The voltage conversion ratio of basic dc/dc converters is limited due to the influence of parasitic elements of circuits and components. In this article, a family of passive circuits termed as “coat circuits” are proposed for conventional dc/dc converters. Not only voltage step-up capacity can be improved but also the voltage stress of components can be decreased by adding coat circuits to basic dc/dc converters. Moreover, no additional active switches are needed in the coat circuits, that means the control and driver circuits of the converters are not changed. The Cuk converter with the coat circuit has been analyzed as an example, and a 200 W experimental prototype has been built to verify the validity of the theoretical analysis.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A Novel Configuration of Cross-Switched T-Type (CT-Type) Multilevel
           Inverter
    • Authors: Sheikh Tanzim Meraj;Kamrul Hasan;Ammar Masaoud;
      Pages: 3688 - 3696
      Abstract: This article introduces a novel configuration of multilevel inverter (MLI) with low number of power electric components. The inverter is a combination of two back to back T-type modules using two cross-connected switches. This inverter can operate using dc sources having either same or different voltage ratings. The proposed inverter can also be extended using cascaded connection to obtain higher voltage levels. This MLI and its extensions are suitable for other applications where high voltage is required. The major feature of this MLI is the formation of negative voltage levels without using any H-bridge circuit. Some other advantages of this MLI are low total harmonic distortion and highly efficient output voltage. A low-frequency modulation technique known as nearest level control is applied to produce the high-quality output voltage. The simulation was done using MATLAB/Simulink, while the hardware prototype is build using TMS320F28335 digital signal processor. The performance of the proposed MLI is validated by obtaining the accurate simulation and experimental results.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Research on IPT Resonant Converters With High Misalignment Tolerance Using
           Multicoil Receiver Set
    • Authors: Guangjie Ke;Qianhong Chen;Wei Gao;Siu-Chung Wong;Chi K. Tse;Zhiliang Zhang;
      Pages: 3697 - 3712
      Abstract: This article provides a comprehensive analysis of the contactless resonant converters using a multicoil receiver set for high misalignment tolerance, with emphasis on the cooperative mechanism of multiple coils and a quantitative analysis of the operating characteristics. The collaborative operation of multiple receiving coils with various compensation circuits and connection types is discussed. A series–parallel compensated converter using a DD2Q receiver set with parallel connection for the multiple rectified outputs is used to illustrate the analysis procedure. Two methods are presented here, namely numerical calculation for the normal case and analytical derivation under three typical misalignments. With the help of switching functions, the general output voltage gain can be derived, which provides direct insight into the cooperation of multiple coils and a practical approach for reducing the output fluctuation. Simulation and experimental verifications are included to confirm the analytical results.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Complete Family of Two-Stage Single-Input Multioutput Configurations of
           Interconnected Power Converters
    • Authors: Xiaolu Lucia Li;Zheng Dong;Chi K. Tse;
      Pages: 3713 - 3728
      Abstract: Single-input multioutput converters, constructed by interconnecting dc–dc converters, are used in various applications with advantages of high scalability, low component stress, and power distribution flexibility. This article presents a complete family of two-stage configurations of interconnected dc–dc converters that include conventional voltage-source-mode (VSM) converters and the less known current-source-mode (CSM) converters, covering all possible termination types and connection styles. Derivation of 16 possible configurations is presented. These configurations are then compared in terms of power-sharing capability, extended flexibility, mutual effects among interconnected modules, basic control requirements, and load characteristics. On this basis, advantages and disadvantages of different configurations are given. Suitable applications and existing (known) configurations are reviewed, aiming to provide essential information for the design of interconnected converters for different application scenarios. As an illustrative example, a two-stage configuration consisting of a VSM converter as the prestage and two series-connected CSM converters as the poststage is proposed to drive light-emitting diodes under high-input-voltage conditions.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A Novel Accurate Adaptive Constant On-Time Buck Converter for a Wide-Range
           Operation
    • Authors: Wen-Chin Liu;Ching-Jan Chen;Ching-Hsiang Cheng;Hsuan-Ju Chen;
      Pages: 3729 - 3739
      Abstract: The ripple-based constant on-time (COT) control with ripple compensation has been widely adopted in buck converters in the recent years because of its simplicity, fast transient response, and high light-load efficiency. However, this control has the potential issues of instability and excessive load transient response with wide input/output voltage range conditions in the power management integrated circuit (PMIC) applications. In this article, an accurate adaptive COT control scheme is proposed to solve these problems. The control scheme achieves accurate output voltage, and nearly constant quality factor and well transient response over a wide-range operation with simple circuit. The small-signal model is also derived based on the describing function (DF) technique for design optimization. Finally, the simulations and experimental verifications were conducted to verify the proposed concepts.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Reactive Power Elimination for High Conversion-Ratio Bidirectional
           Resonant Converter
    • Authors: Hwasoo Seok;Adrià Junyent-Ferré;Honnyong Cha;Minsung Kim;
      Pages: 3740 - 3753
      Abstract: This article presents a reactive power elimination method for high conversion-ratio bidirectional resonant converter with ripple-free current at the low voltage side. When transferring power in the backward mode operation, the converter with heavy loads suffers from significant reverse current that generates reactive power. By adjusting the right amount of phase of the pulsewidth modulation signals, we can eliminate the reverse current and the corresponding reactive power. We derive the voltage gain, calculate the right amount of phase, and identify the load threshold, above which the reverse current appears. We use a 600 W converter prototype to demonstrate the performance of the proposed converter.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A Constant On-Time Buck Converter With Analog Time-Optimized On-Time
           Control
    • Authors: Yu-Chen Li;Ching-Jan Chen;Chieh-Ju Tsai;
      Pages: 3754 - 3765
      Abstract: A constant on-time buck converter with analog time-optimized on-time control (OTC) is proposed to achieve fast load-current step-up transient response for high slew-rate loads. The proposed control first implements a constant on-time converter embedded with analog time-optimized OTC and solves the prior art issues such as poor light-load efficiency, high quiescent current, and the dependence on the power stage parameters of OTC. The body diode control, which minimizes the overshoot with simple logic and capacitor-current sensor, is proposed for load current step-down. The proposed control was implemented into an integrated circuit using 0.18 μm CMOS process with a chip area of 1.423 mm2, where OTC only occupies 0.054 mm2. The simulation results show 51.3% and 55.5% reductions of voltage deviation after enabling the proposed control functions at load step-up and step-down, respectively. Measurement results show that the undershoot of output voltage improves 52.4% after enabling OTC for a 0.84 A load step-up.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Varying Switching Frequency Control for Current-Fed Dual-Active Bridge
           DC–DC Converter With Constant Flux Density Change for Transformers
    • Authors: Deshang Sha;Tengfei Sun;Jiankun Zhang;
      Pages: 3766 - 3777
      Abstract: For current-fed dual-active bridge bidirectional dc–dc converters, a PWM plus dual phase shifted (PPDPS) control with varying switching frequency was proposed. To prevent magnetic core saturation, the flux density change of the transformer is kept constant in spite of the battery voltage and the load. The detailed loss breakdown was implemented by comparing with the conventional PPDPS with fixed switching frequency. With the proposed control, zero voltage switching performance is better with lower battery voltage and the conversion efficiency can be improved compared with fixed switching frequency control. The closed loop control implementation was given in detail. Both the steady state and dynamic response with different battery voltages are good. The effectiveness of the proposed control is verified by the experimental results of a 2.4-kW laboratory prototype.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A Dual-Switch Discontinuous Current-Source Gate Driver Overcoming the
           Current Diversion Problem for a Buck VRM
    • Authors: Iman Abdali Mashhadi;Majid Pahlevani;
      Pages: 3778 - 3793
      Abstract: In this article, a novel dual-switch discontinuous current-source gate driver (CSD) suitable for driving the high-side mosfet (HS mosfet) of buck voltage regulator module (VRM) is presented. The proposed gate driver completely solves the gate current diversion problem, which most of the previous CSDs suffer from, during turn-off transition. Thus, in comparison to most of the previous CSDs, the proposed gate driver achieves to turn-off the power mosfet considerably faster and with much higher effective gate current, which leads to significant reduction of turn-off losses. Whereas, turn-on losses of buck VRM HS mosfet driven by the proposed CSD and the previous CSDs are equal. Furthermore, the introduced gate driver consists of the minimum number of control switches and circuit elements, compared to previous CSDs. The proposed gate driver is analyzed and a prototype of the driver operating at 1 MHz is implemented in order to validate the theoretical analysis.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Expandable N-Legged Converter to Drive Closely Spaced Multitransmitter
           Wireless Power Transfer Systems for Dynamic Charging
    • Authors: Farzad Farajizadeh;D. Mahinda Vilathgamuwa;Dejan Jovanovic;Prasad Jayathurathnage;Gerard Ledwich;Udaya Madawala;
      Pages: 3794 - 3806
      Abstract: Expandable and flexible wireless power transfer (WPT) systems have been in demand in numerous industry applications, especially for dynamic chargers in electric vehicles. Those systems, however, bring about certain technical issues such as modulation technique and topology of the transmitter side, and transferred power profile of the transmitters. In this article, a new converter topology to drive closely spaced segmented dynamic wireless power transfer (DWPT) systems is proposed. The proposed converter can be expanded to cater for different number of transmitters, and it can provide a uniform transferred power profile throughout the path of transmitter coils, known as track. Furthermore, this article focuses on analyzing the operation of the converter and the effect of closely spaced transmitters over its operation. To show the effectiveness of the proposed topology and its modulation technique, the converter is simulated and experimentally tested using a laboratory prototype. The results are compared and analyzed, and their close agreement shows the validity of the proposed technique.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Properties and Synthesis of Lossless Snubbers and Passive Soft-Switching
           PWM Converters
    • Authors: Xiang Yu;Jianhui Su;Shilin Guo;Shu Zhong;Yong Shi;Jidong Lai;
      Pages: 3807 - 3827
      Abstract: This article investigates the synthesis of lossless snubbers and passive soft-switching converters, as well as their general properties, including topological properties and electrical properties. The aim is to find the possible simplest snubbers and soft-switching converters and to give suggestions on applications of the snubbers and the soft-switching converters. On one hand, the synthesis and the topological properties of the snubbers and the converters determine the complexity of the topologies and help find the least requirement that passive soft switching needs to fulfill. The topological properties are investigated by addressing the basic issues induced by the inductor/capacitor added for passive soft switching. Based on the topological properties, the snubbers and the converters are synthesized. On the other hand, the electrical properties determine the performance of the snubbers and converters, help understand the limitations and are investigated by two case studies accompanied with experimental verification. By investigation of the general properties, the possible simplest snubber is given, the tradeoff between the complexity and performance is discussed in detail, the suggestion of snubber applications is presented, and three kinds of reported passive soft-switching converters which are believed to have the most potential of wide application are discussed.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Common-Mode Voltage Elimination for Dual Two-Level Inverter-Fed
           Asymmetrical Six-Phase PMSM
    • Authors: Zewei Shen;Dong Jiang;Zicheng Liu;Donglin Ye;Jian Li;
      Pages: 3828 - 3840
      Abstract: The voltage-source inverter with pulsewidth modulation (PWM) is widely used in motor drive applications owing to the technical maturity and simplicity. However, the inverter operating in the discrete and impulse state generates the high-frequency common-mode voltage (CMV) in the neutral point terminal of stator winding, which induces the negative effects. This article proposes a CMV elimination modulation scheme for the dual two-level inverter-fed asymmetrical six-phase permanent magnet synchronous motor, which has two sets of three-phase windings spatially shifted by 30° electrical degrees. The modulation algorithm shifts the PWM signals with the designed end-to-end cyclic sequence, which can retain the zero-voltage vectors for each sub-CMV of dual three-phase windings and theoretically eliminate the total CMV for the motor drive system. The validation of the proposal is verified by simulations and experiments.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Real-Time HIL Emulation for a Segmented-Rotor Switched Reluctance Motor
           Using a New Magnetic Equivalent Circuit
    • Authors: Xiaodong Sun;Kaikai Diao;Gang Lei;Youguang Guo;Jianguo Zhu;
      Pages: 3841 - 3849
      Abstract: This article presents a new magnetic equivalent circuit (MEC) for a real-time emulation of a 16/10 segmented-rotor switched reluctance motor (SSRM) based on the hardware-in-the-loop (HIL) configuration. The proposed real-time MEC contains the reluctances of slot leakage, air gap, and iron core of the SSRM. To speed up the emulation, a ten-by-ten matrix system is developed for the MEC. A new algorithm is proposed to solve the matrix system to reduce the computation time. To carry out the experiment, the HIL is employed in this article. It can provide a precise and real-time condition for the application of the new method. In the test bench, the field-programmable gate array provides an operating platform to realize the real-time emulation of the MEC model. As verified, the proposed real-time MEC model benefits the real-time emulation and the performance evaluation of the SSRM. The proposed method can be applied to other switched reluctance motors as an efficient way to verify their real-time characteristics with high accuracy and low emulation cost.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Simplified Fault-Tolerant Model Predictive Control for a Five-Phase
           Permanent-Magnet Motor With Reduced Computation Burden
    • Authors: Tao Tao;Wenxiang Zhao;Yuxuan Du;Yu Cheng;Jihong Zhu;
      Pages: 3850 - 3858
      Abstract: This article proposes a fault-tolerant finite control set model predictive control for a five-phase permanent-magnet (PM) motor drive, which offers reduced computation burden and simplified control model. The virtual voltage vectors synthesized from two basic vectors are used to reduce the computation burden. Meanwhile, the steady-state performance is improved. Combining with a reduced decoupling matrix, the discrete model of the five-phase PM motor before and after fault remains unchanged. So, the reconfiguration of the control structure is minimal. Then, a control set and corresponding switching sequence are proposed, which are very suitable for the real-time system. Finally, the validity of the proposed fault-tolerant control is proved by experiments.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Binary Diagnosis of Hall Effect Sensors in Brushless DC Motor Drives
    • Authors: Ali Mousmi;Ahmed Abbou;Yassine El Houm;
      Pages: 3859 - 3868
      Abstract: Commonly, three Hall effect sensors are used to detect the rotor position in brushless motors. Since one of these sensors may fail and lead to unstable operation, fault-tolerant control (FTC) of Hall sensor drives has attracted renewed research attention recently to ensure very high reliability. This article presents simple combinatory functions to detect fails in Hall effect sensors based only on Hall sensors signals, which require just a memory of 3 b. The proposed method guarantees more reliability and overcomes erroneous alarms that can be triggered by previous fault diagnosis methods using the information on the observed acceleration, which may be the subject of unexpected variations and lead consequently to false diagnosis. In addition, the article opens the discussion about the BLDC startup with a faulty sensor, in order to perform FTC algorithms ensuring a long use of the motor given the difficulty to repair Hall effect sensors inserted between the coils inside the stator. To confirm the theoretical analysis, experimental results are reported and limitations on the performances of the faulty system in terms of fault detection and signal reconstruction algorithm are discussed. The proposed schemes circuits can be inserted in conventional drive systems or by being placed between the existing driver and the motor.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Sensorless Control of Linear Vernier Permanent-Magnet Motor Based on
           Improved Mover Flux Observer
    • Authors: Jinghua Ji;Yang Jiang;Wenxiang Zhao;Qian Chen;Anchen Yang;
      Pages: 3869 - 3877
      Abstract: Linear vernier permanent-magnet (LVPM) motors have a bright future in long stroke applications, because of their merits of high efficiency, high force capability, and low cost. However, the position sensor for the LVPM motor costs huge. In this article, a sensorless control based on an improved mover flux observer is proposed. The proposed mover flux observer combines a disturbance observer and a feedback controller. It can be easily implemented, which results in low computation burden. Due to simple tuning parameters of this observer, the mover flux observer can have strong robustness to the dc bias and the initialization errors of integrators that are main weakness of flux model. This proposed observer also does not introduce error in either the estimated mover flux amplitude or phase. Then, a phase-locked loop is used to detected position information from the mover fluxes. Finally, the LVPM motor operates by using the estimated position and speed signals. Simulation and experimental results of the LVPM motor demonstrate the accuracy and dynamic performance of the proposed sensorless operation.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A Novel Variable DC-Link Voltage Control Method for PMSM Driven by a
           Quasi-Z-Source Inverter
    • Authors: Shuxin Xiao;Xin Gu;Zhiqiang Wang;Tingna Shi;Changliang Xia;
      Pages: 3878 - 3890
      Abstract: The variable dc-link voltage control methods can effectively improve the operation efficiency of the permanent magnet synchronous motor (PMSM) drive system. At present, the reported variable dc-link voltage control methods applied in the PMSM driven by a quasi-Z-source inverter (qZSI) are limited to the analytical calculation methods (ACMs) based on the system model. The ACMs demand measurement of qZSI's input voltage and usually need a larger margin index due to the inaccurate model to calculate the reference dc-link voltage. To overcome the restriction, this article proposes a novel variable dc-link voltage control method that can indirectly adjust the dc-link voltage with an extra proportional–integral (PI) regulator. Basic principle of the method is introduced and two design rules of the PI regulator are illustrated. Besides, necessary conditions that need to be met when obtaining the feedback signal of the PI regulator are analyzed. Finally, experiments are performed to validate the feasibility and effectiveness of the proposed method. In comparison with the ACMs, the proposed method gets rid of the dependence on an extra voltage sensor to measure the input voltage and can reserve less margin for the dc-link voltage, which contributes to less cost and higher efficiency of the drive system. Besides, the proposed method is easy and convenient to apply.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Design and Control Method for a Surface-Mounted Permanent Magnet Motor
           Drive System With Passive Output Power Network
    • Authors: Hyeon-Gyu Choi;Kahyun Lee;Jung-Ik Ha;
      Pages: 3891 - 3905
      Abstract: This article proposes a method to extend the operating area of the surface permanent magnet motor by inserting the passive power networks between the motor and the voltage source inverter (VSI). In the conventional motor drive system, since the operating area is limited by the maximum voltage, which is synthesized by the inverter, the output torque capability is reduced in the high-speed region. In order to extend the operating area, two types of passive power networks are proposed in this article. The power networks supply the reactive power to the motor for amplifying the motor terminal voltage. Due to the actions, the proposed motor drive system can utilize a higher maximum motor terminal voltage than that in the conventional drive systems. Depending on the network types, the operating point at which the maximum power or torque is generated is shifted to a high speed. The design, control, and analysis methods of the proposed system are presented in this article. The effectiveness of the proposed system is verified through the experimental results.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • An Improved Direct Torque Control of Three-Level Dual Inverter Fed
           Open-Ended Winding Induction Motor Drive Based on Modified Look-Up Table
    • Authors: Ravi Eswar Kodumur Meesala;Vinay Kumar Thippiripati;
      Pages: 3906 - 3917
      Abstract: The induction motor (IM) drive with direct torque control scheme (DTC) turns prominent for industrial applications. However, it retains disadvantage of high torque ripples. The conventional look-up table for DTC scheme is structured with selection of reverse voltage vectors (VVs) when flux and torque errors crosses lower hysteresis boundary condition. This results in higher torque ripples and increase in switching frequency. In this article, modified look-up table for DTC of three-level dual voltage source inverter fed open-ended winding IM drive is proposed, where the VVs selection for lower hysteresis boundary conditions of torque and flux are restructured with null voltage states. The selection of suitable null voltage switching states from the various possible combinations of dual inverter switchings is based on minimization of switching state transitions. To nullify flux instability at zero speed, proper active VVs are placed at hysteresis flux +1 and torque 0 condition in the modified look-up table. These overall effective modifications in the proposed DTC scheme enjoys the benefits of reduction in torque ripple, switching frequency, and stable flux maintenance. The MATLAB simulations and practical investigations are conducted for existing and proposed DTC schemes. From these results, the benefits of the proposed DTC over existing DTC schemes are verified.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Balanced Submodule Operation of Modular Multilevel Converter-Based
           Induction Motor Drive for Wide-Speed Range
    • Authors: Yerraguntla Shasi Kumar;Gautam Poddar;
      Pages: 3918 - 3927
      Abstract: Operation of the conventional modular multilevel converter (MMC) at low frequencies for the induction motor drive is difficult. The peak-to-peak voltage ripple of submodule (SM) capacitor increases abnormally at low frequencies of the drive. Recently, the problem of high voltage ripple has been solved by using back-to-back MMC without overloading the converter till very low frequency of the drive. In this back-to-back configuration, the grid-side MMC generates constant dc current source at its output instead of dc voltage source. Using this current source as input, the motor-side MMC drives a three-phase induction motor. It is shown that the voltage ripple of SM capacitor remains constant till very low frequency due to the dc current source. However, the average capacitor voltage controllers do not guarantee balanced operation of individual SM. In this article, the need for balancing controller of individual SM capacitors of back-to-back MMC is established experimentally. Therefore, this article proposes additional voltage-balancing controllers for the individual capacitor of grid-side MMC and motor-side MMC without disturbing the average controllers. The operating principle of this balancing controller has been presented analytically and verified experimentally. Finally, the operation of the drive with the proposed balancing controller is presented for wide speed range.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Improved Transient-Based Overmodulation Method for Increased Torque
           Capability of Direct Torque Control With Constant Torque-Switching
           Regulator of Induction Machines
    • Authors: Ibrahim Mohd Alsofyani;Kyo-Beum Lee;
      Pages: 3928 - 3938
      Abstract: In this article, a simple overmodulation method is proposed for achieving fast direct torque control with a constant torque-switching controller (CTSR-DTC) in induction machines. The conventional overmodulation method applied to CTSR-DTC focuses on attaining and maintaining the voltage vector with the largest tangential component to the locus of the stator flux. The selected voltage vector is held during the transient state and fed into the switching table. Nevertheless, unlike a classical DTC, the CTSR activates both zero- and active-voltage vectors owing to the nature of its operation. As a result, the optimized active voltage during an overmodulation cannot be maintained throughout the complete torque transient owing to an interruption by the zero-voltage vectors. To overcome this problem, the proposed method modifies the CTSR output to eliminate the zero-voltage vectors only during a transient state. Consequently, a full exploitation of the overmodulation is achieved, and hence an excellent torque dynamic response can be obtained when torque is demanded. Simulation and experimental results are provided to validate the effectiveness of the proposed overmodulation strategy.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Online Boundary Computation Using Sampled Voltage Reference for Bus
           Clamping PWM-Based Hysteresis-Controlled VSI-Fed IM Drive
    • Authors: Joseph Peter;Mohammed Shafi KP;Lakshmi R;Rijil Ramchand;
      Pages: 3939 - 3950
      Abstract: A current error space phasor based hysteresis current controller (HCC) with online computation of the current error boundaries using estimated sampled voltage references (SVR) for a two-level voltage source inverter (VSI) fed induction motor (IM) drive is proposed in this article. The space vector based current error of a two-level VSI-fed IM is monitored to keep the current error within the precalculated boundaries. The boundaries are computed knowing voltage error vector estimated from the current error information along α and β axes of IM. Vector selection logic is deduced to extract the features of voltage-controlled (VC) –30° and 60° bus clamping (BC) space vector pulsewidth modulation (SVPWM) based VSI-fed IM drive. The proposed HCC produces phase voltage harmonic spectrum and current error trajectories similar to that of a constant switching frequency—VC-BCSVPWM drive. It ensures adjacent voltage vector switching and retains all inherent advantages of a conventional HCC such as fast current control and has got a simpler controller implementation. A simulation model using MATLAB/Simulink is developed and analyzed over a wide speed range and experimentally validated using a dSPACE controller board on a 2.2 kW, 415 V, 3ϕ IM drive.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Accurate Calculation and Sensitivity Analysis of Leakage Inductance of
           High-Frequency Transformer With Litz Wire Winding
    • Authors: Ke Zhang;Wu Chen;Xiaopeng Cao;Pengpeng Pan;Syed Waqar Azeem;Guangyao Qiao;Fujin Deng;
      Pages: 3951 - 3962
      Abstract: Leakage inductance is an important parameter in a high-frequency transformer for its influence on power transmission performance and the soft switching of converters. Nowadays, Litz wire is widely used to control winding loss and reach high efficiency. However, it is not an easy task to accurately calculate its leakage inductance. This article presents a detailed model of leakage energy in Litz wire, and proposes an accurate closed-form expression for calculating the leakage inductance in a high-frequency transformer. The skin effect and the proximity effect of Litz wire are taken into account in two-dimensional polar coordinates, and the filling factor of Litz wire is also considered. A global sensitivity analysis is performed to assess the influence of each parameter on the overall leakage inductance. Finally, two transformer prototypes are made to verify the accuracy of the proposed analytical expression.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Chips Classification for Suppressing Transient Current Imbalance of
           Parallel-Connected Silicon Carbide MOSFETs
    • Authors: Junji Ke;Zhibin Zhao;Peng Sun;Huazhen Huang;James Abuogo;Xiang Cui;
      Pages: 3963 - 3972
      Abstract: This article addresses the influence of parameters spread on transient current distribution among parallel-connected silicon carbide (SiC) mosfets and proposes a chips classification method to suppress current imbalance. A comprehensive comparison of parameter spread between silicon (Si) and SiC mosfets is first presented. Then, a new classification criterion, referred to in this article as a distance coefficient of transfer curves (DCTC), is proposed to characterize device spread. In addition, the sensitivity analysis of transient current imbalance (TCI) to device spread is carried out. It is found that TCI increases almost linearly with increasing DCTC. Furthermore, a hierarchical cluster algorithm is developed to achieve an automated chips classification for multiple devices intended for paralleled application. This algorithm may as well facilitate the chip selection process for multiple-chip power module packaging. Moreover, the influence of operating temperature on classification is also discussed. It should be noted that chips classification needs to consider real application conditions and package parasitic. Finally, a test bench with a round layout is designed, to keep circuit layout asymmetry to a minimum, and used to experimentally verify the performance of the classification method. The experimental results validate the effectiveness of the proposed classification method for suppressing TCI.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Stepwise Design Methodology and Heterogeneous Integration Routine of
           Air-Cooled SiC Inverter for Electric Vehicle
    • Authors: Zheng Zeng;Xin Zhang;Frede Blaabjerg;Hao Chen;Tianfu Sun;
      Pages: 3973 - 3988
      Abstract: Carrying on SiC devices, the air-cooled inverter of the electric vehicle (EV) can eliminate the traditional complicated liquid-cooling system in order to obtain a light and compact performance of the powertrain, which is considered as the trend of next-generation EV. However, the air-cooled SiC inverter lacks strategic design methodology and heterogeneous integration routine for critical components. In this article, a stepwise design methodology is proposed for the air-cooled SiC inverter in the power module, dc-link capacitor, and heat sink levels. In the power module level, an electrical–thermal–mechanical multiphysics model is proposed. The multidimension stress distribution principles in a six-in-one SiC power module are demonstrated. An improved power module is presented and confirmed by using the observed multiphysics design principles. In the dc-link capacitor level, ripple modeling of the inverter and capacitor are created. Considering the tradeoffs among ripple voltage, ripple current, and cost, optimal strategies to determine the material and minimize the capacitance of the dc-link capacitor are proposed. In the heat sink level, thermal resistance of air-cooled heat sink is modeled. Structure and material properties of the heat sink are optimally designed by using a comprehensive electro-thermal analysis. Based on the optimal design results, the prototypes of the customized SiC power module and heterogeneously integrated air-cooled inverter are fabricated. Experimental results are presented to demonstrate the feasibility of the designed and manufactured air-cooled SiC inverter.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A New Lumped-Charge Modeling Method for Power Semiconductor Devices
    • Authors: Yaoqiang Duan;Francesco Iannuzzo;Frede Blaabjerg;
      Pages: 3989 - 3996
      Abstract: This article proposes a new lumped-charge model for power semiconductor devices. The existing lumped-charge model, due to its linear modeling method, has some limitations that will impair the accuracy of the model. First, this article analyses the restriction of the traditional lumped-charge modeling method. Then, based on the limitation analysis, a new lumped-charge modeling method is presented and improves the accuracy of the traditional one while keeping its advantages. In this new model, the relationship between the ambipolar current and the LCs in the power devices is redefined. Finally, the new method is implemented to an insulated-gate bipolar transistor (IGBT) model and a PiN freewheeling diode. The accuracy of the models is verified by experiment including both the static and transient characteristics and compared with the traditional IGBT model.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A High Efficiency and Fast Transient Digital Low-Dropout Regulator With
           the Burst Mode Corresponding to the Power-Saving Modes of DC–DC
           Switching Converters
    • Authors: Jian-He Lin;Shang-Hsien Yang;Balakumar Muniandi;Yu-Sheng Ma;Chia-Ming Huang;Ke-Horng Chen;Ying-Hsi Lin;Shian-Ru Lin;Tsung-Yen Tsai;
      Pages: 3997 - 4008
      Abstract: The proposed digital low-dropout regulator uses nonlinear switching control (NLSC) technique to suppress voltage ripple to less than 6 mV when the switching noise voltage of a switching regulator operating in a power-saving mode is greater than 50 mV. In addition, the NLSC technique improves the current efficiency by reducing the quiescent current to less than 10 μA and reduces the switching power loss through variable switching frequency control. With a load step of 1–20 mA, the transient response time is 1.3 μs and the peak current efficiency is 99.8% at heavy loads.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • On the Optimization of a Class-E Power Amplifier With GaN HEMTs at
           Megahertz Operation
    • Authors: Kawin North Surakitbovorn;Juan M. Rivas-Davila;
      Pages: 4009 - 4023
      Abstract: Class-E power amplifiers have regained academic interest over the past decades due to the introduction of new high-performance wide-bandgap semiconductor devices and the increasing demand for high-efficiency power amplifiers. While these power devices, notably GaN HEMTs, have exceptional performance at megahertz operation, they also display an additional loss component due to $C_{{rm oss}}$ at this frequency. Unfortunately, the dependence of this loss term on the peak voltage and the device size is the opposite of that of the conduction loss. In this article, we mathematically analyze the operation of a Class-E amplifier to find the optimal input voltage and device sizing where the sum of these two losses is minimized. From this analysis, we have found that the common design approach of maximizing device voltage rating and area to get the best efficiency no longer holds for some operating conditions. Furthermore, we examine the constraints that dictate when this optimization equations can and cannot be used, as well as propose a distributed loss model for the $C_{{rm oss}}$ loss based on a generalized Steinmetz equation (GSE) to allow this new loss term to be easily simulated. To verify our mathematical analysis and to demonstrate the applications of the proposed GSE-based $C_{{rm oss}}$ loss model, two design examples are provided. They consist of a choke-input Class-E amplifier at 10 MHz and a variable-resistance Class-E amplifier at 40.68 MHz. The experimental results on these two design examples show good agreements with our analysis.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Reliability Assessment of Multistate Degraded Systems: An Application to
           Power Electronic Systems
    • Authors: Vahid Samavatian;Hossein Iman-Eini;Yvan Avenas;
      Pages: 4024 - 4032
      Abstract: This article demonstrates the feasibility of using a multistate degraded system analysis for obtaining much more accuracy in reliability evaluation. The proposed method is capable of estimating system-level reliability, while mission profile and physics of failure of the system's items are taken into account. In addition, the self and mutual degradation effects of items on the operation of the global system have been considered. Not only does the proposed framework can be employed in determining the reliability of the degraded systems in terms of multistate functions, but also obtains the states of the systems by estimating the system state probabilities. As an application, a power electronic system containing three critical items has been studied. In this case study, two power semiconductors and a capacitor have been considered as three degradation processes and their aging effects on the useful lifetime estimation of the power electronic system has been discussed.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • An Impedance-Based Stability Assessment Methodology for DC Distribution
           Power System With Multivoltage Levels
    • Authors: Pengpeng Pan;Wu Chen;Liangcai Shu;Han Mu;Ke Zhang;Miao Zhu;Fujin Deng;
      Pages: 4033 - 4047
      Abstract: Impedance-based methods are effective for stability assessment of cascaded systems. However, the dc distribution power system (DPS) is becoming increasingly complex, incorporating multivoltage levels, many dc buses, and numerous converters. Consequently, conventional stability criteria, such as Middlebrook criterion and its extensions, may not have the ability to judge stability very succinctly. Thus, more research work related to stability evaluation of dc DPS with multivoltage levels needs to be carried out. This article proposes an impedance-based stability assessment methodology. First of all, a unified form of the system is obtained regardless of its structures and operating modes, based on classification of any converter as either a bus voltage-controlled converter or a bus current-controlled converter. Then, according to the two-port small-signal model, the equivalent loop gain of the system is derived precisely. It should be noted that intermediate bus converter could adopt output current or output voltage control modes, which will have influence on the equivalent loop gain expression. After that, the stability requirement of the system is given by introducing the Nyquist criterion to the equivalent loop gain. Finally, an experimental prototype is established to validate the effectiveness of the proposed criterion.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Data-Driven Approach for Fault Prognosis of SiC MOSFETs
    • Authors: Weiqiang Chen;Lingyi Zhang;Krishna Pattipati;Ali M. Bazzi;Shailesh Joshi;Ercan M. Dede;
      Pages: 4048 - 4062
      Abstract: This article proposes an unsupervised learning approach for fault prognosis of silicon carbide (SiC) mosfets. The proposed approach utilizes the changing trend of a device's voltage, current, temperature, and other device characteristics with its degradation. The failure modes of semiconductors are reviewed along with existing methods for fault prognosis. The proposed approach is the first to address prognostics of SiC devices, and it can avoid the effects from system noise and data errors. It is not limited to offline analysis and is targeted at online implementation. It is easy to implement on standard digital platforms, and has fast computational speed. Offline data analysis is performed to verify the effectiveness of the proposed method, and a processor-in-the-loop system is used to verify its ability to perform online fault prognosis.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Capacitor ESR and C Monitoring in Modular Multilevel
           Converters
    • Authors: Fujin Deng;Qian Heng;Chengkai Liu;Xu Cai;Rongwu Zhu;Zhe Chen;Wu Chen;
      Pages: 4063 - 4075
      Abstract: The capacitor is one of the weakest components in the modular multilevel converter (MMC). The rise of equivalent series resistance (ESR) is a prominent character to monitor the lapsed capacitor, but current research works only focus on capacitance and neglect ESR of capacitors in the MMC. This article proposed a sorting-based monitoring strategy for capacitors in the MMC, which monitors not only the capacitance but also the ESR of capacitor. This article reveals the relationship among the capacitor's ESR, capacitance, current, and energy. Based on the relationship, the ESRs and capacitances of submodule capacitors in the arm are indirectly sorted, respectively, and only the capacitor with biggest ESR and the capacitor with smallest capacitance in the arm are monitored. The proposed strategy not only realizes both ESR and capacitance monitoring in the MMC, but also proposes a simplified monitoring algorithm for MMCs with a large number of capacitors. The simulation and experimental results confirm the effectiveness of the proposed monitoring strategy for MMCs.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Small-Signal Modeling of LLC Converters Using
           Homopolarity Cycle
    • Authors: Mehdi Mohammadi;Franco Degioanni;Mohammad Mahdavi;Martin Ordonez;
      Pages: 4076 - 4093
      Abstract: The widespread use of the LLC converter in dc–dc applications has increased the importance of small-signal modeling to control the converter below- to above-resonant frequency. The analysis of LLC converters is complicated, since they process the electrical energy through a high-frequency resonant tank that causes excessive nonlinearity. As a result of this complexity, small-signal modeling of the LLC converter is traditionally performed using empirical methods, iterative simulation approaches, or theory limited to the vicinity of the resonant frequency. Often, such approaches may lead to limited insight (just empirical trends) or low accuracy below and above resonance. This article proposes a new average small-signal modeling technique for the LLC converter, and it is performed in the time domain. The proposed technique is based on the analysis of the homopolarity cycle and accurately predicts not only the small-signal dynamic behavior of the LLC converter at resonance, but also below and above resonance. By using the homopolarity cycle, the theoretical analysis of the LLC converter is significantly simplified to a level that the small-signal dynamic behavior of the LLC converter is expressed by two second-order circuit models. Experimental and simulation results of a 650-W LLC converter are provided to verify the theoretical analyses and accuracy of the circuit models. The results have shown that the proposed small-signal circuit models can accurately predict the small-signal dynamic behaviors of the LLC converter from below- to above-resonant operations.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Duty Ratio Stability and Average Steady-State Error of Two-Level
           Current-Mode Wide-Bandwidth Switching Power Amplifiers
    • Authors: Zhonglei Yu;Lei Gong;Changsheng Zhu;
      Pages: 4094 - 4104
      Abstract: Nowadays, high-frequency switching power amplifiers (SPA) have been studied widely; bulk of the researches were focused on audio power amplifiers. In active magnetic bearing (AMB) systems, high-frequency electromagnetic excitation caused by rotor imbalance can affect the performance of the SPA, so the traditional SPA cannot meet the requirements of the AMB systems. Therefore, on the premise of ensuring larger power, the frequency of the SPA should be improved to ensure the normal operation of the AMB system. Two-level pulsewidth modulation (PWM) current-mode SPAs are widely used in AMB systems. In order to broaden the bandwidth and to reduce the average steady-state error current, SiC power devices based SPA with a high bus voltage and a high switching frequency was designed. The basic principle and the linearized control model of SPAs are introduced. Then, the duty ratio stability and average steady-state error current of the SPAs are analyzed based on the output ripple current. When the PWM modulator is designed by either the discrete devices or the integrated chips, the critical gains to ensure the duty ratio stability are, respectively, analyzed based on the slope matching and the nonideal characteristic of operational amplifiers. Hence, two methods to reduce the average steady-state error current are proposed, respectively. One is to adjust the offset voltage of triangular carrier for the P controller, the other is to use a proportional integral (PI) controller. The offset adjusting method allows the SPA to achieve better dynamic performance and wider bandwidth. The proportional integral (PI) controller can reduce the average steady-state error current but narrows the bandwidth. Finally, the experiment results are in good agreement with the theoretical analyses.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Integral Sliding Mode Control for Starting Speed Sensorless Controlled
           Induction Motor in the Rotating Condition
    • Authors: Lifeng Gou;Chenchen Wang;Minglei Zhou;Xiaojie You;
      Pages: 4105 - 4116
      Abstract: Starting in the rotating condition is an important technology for induction motor (IM) speed sensorless control. The key of this technology is that the initial speed of the IM in the rotating condition should be estimated quickly and accurately. In this article, an integral sliding mode control method based on the nonlinear model of the rotor back electromotive force is designed to start a speed sensorless controlled IM in the rotating condition. The stability is guaranteed by Lyapunov stability analysis, and the robustness to rotor time constant and disturbance are analyzed. Meanwhile, in comparison with the proposed control method, the existing input–output feedback linearization (IOFL) control method is introduced and the stability and robustness are also analyzed. Compared with the existing IOFL control method, the proposed control method can estimate the initial speed in the rotating condition without overshoot and has better dynamic performance and robustness. In addition, the proposed control method can be applied not only to the restart operation but also to the normal operation. Only a single control strategy is required from the restart operation to the normal operation. The proposed method is verified by simulation and experiments using a 7.5 kW IM.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A New Reaching Law for Antidisturbance Sliding-Mode Control of PMSM Speed
           Regulation System
    • Authors: Yaoqiang Wang;Yutao Feng;Xiaoguang Zhang;Jun Liang;
      Pages: 4117 - 4126
      Abstract: In this article, in order to optimize the dynamic performance of the permanent magnet synchronous motor (PMSM) speed regulation system, a nonlinear speed-control algorithm for the PMSM control systems using sliding-mode control is developed. First, a sliding-mode control method based on a new sliding-mode reaching law (NSMRL) is proposed. This NSMRL includes the system state variable and the power term of sliding surface function. In particular, the power term is bounded by the absolute value of the switching function, so that the reaching law can be expressed in two different forms during the reaching process. This method can not only effectively suppress the inherent chattering, but also increases the velocity of the system state reaching to the sliding-mode surface. Based on this new reaching law, a sliding-mode speed controller (SMSC) of PMSM is designed. Then, considering the large chattering phenomenon caused by high switching gain, an improved antidisturbance sliding-mode speed controller method, called SMSC + ESO method, is developed. This method introduces an extended state observer to observe the lumped disturbance and adds a feedforward compensation item based on the observed disturbances to the SMSC. Finally, simulation and experimental results both show the validity of the proposed control method.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Active Power Oscillation and Suppression Techniques Between Two Parallel
           Synchronverters During Load Fluctuations
    • Authors: Zhikang Shuai;Wen Huang;Zheng John Shen;An Luo;Zhen Tian;
      Pages: 4127 - 4142
      Abstract: Active power oscillation is observed when two or more parallel synchronverters undergo load fluctuations, potentially impacting the safe operation of the synchronverters. This article provides a fundamental analysis for the power oscillation mechanisms and proposes a new control strategy for suppressing power oscillation especially the oscillation excitation is proposed. It is found that power oscillation is inherently caused by weak damping and large inertia of the synchronverters under the condition of undesirable instantaneous active power sharing. Then, the condition for reducing the oscillation excitation of synchronverters, which is caused by undesirable instantaneous active power sharing, is deduced. The new control strategy effectively suppresses the power oscillation by adding a virtual damping element for enhancing the system damping and a virtual reactance for reducing the oscillation excitation to the conventional control scheme without changing the basic dynamic and steady characteristics of the synchronverters. The theoretical analysis and the proposed oscillation suppression control techniques are validated with an extensive hardware-in-loop simulation study.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Multirate Harmonic Compensation Control for Low Switching Frequency
           Converters: Scheme, Modeling, and Analysis
    • Authors: Hao Tian;Yun Wei Li;Qing Zhao;
      Pages: 4143 - 4156
      Abstract: Using the grid-interfacing voltage-source converters (VSCs) to perform harmonic control as a smart ancillary function is increasingly studied in recent years. Different from the traditional dedicated harmonic compensation converters, the main function of the high-power smart converters is still delivering real power at a low switching frequency (e.g., 2 kHz). It is challenging to compensate harmonics with low switching frequency VSCs due to the low sampling rate and large system delay. This article proposes a multirate control scheme and derives the accurate multirate model to improve harmonic control. The multirate control scheme consists of high-rate harmonic control and synchronous sampled fundamental control. With the proposed control scheme, the advantages of the conventional synchronous sampling method and the benefits of the high sampling rate are achieved simultaneously. To accurately model the low switching VSC with two different sampling rates, the lifting method is introduced to achieve the discrete-time system model for this linear periodic time-varying system. The frequency response and stability analysis are carried out based on the lifted model. The modeling method, as well as the enhanced harmonic control performance of the multirate control structure, is validated in the experiments.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Improved Modulation Strategy for Single-Phase Single-Stage Isolated
           AC–DC Converter Considering Power Reversion Zone
    • Authors: Fengjiang Wu;Xiaoguang Li;Suhua Luo;
      Pages: 4157 - 4167
      Abstract: In this article, an improved modulation strategy for the single-phase single-stage isolated bidirectional ac–dc converter is proposed. The modulation of ac side cycloconverter is based on the unipolar idea to reduce the switching quantity and the ac side current ripple and provide the bidirectional current flow path. The dc side H-bridge converter is driven by the pulsewidth modulation signals cooperatively to speed up the transformer current and thus to eliminate the voltage spike. Furthermore, the power reversion zone (PRZ) of the converter is verified. The action of the proposed modulation strategy in PRZ is analyzed for the first time. It reveals that the reverse current overshoot is caused in ac-to-dc direction and the voltage spike is caused in dc-to-ac direction. An online switching scheme of the proposed modulation strategies in two power directions is proposed to solve these problems. The detailed experimental results verify the correctness and reliability of the proposed modulation strategy.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Post-Fault Operation of Bearingless Multisector SPM Machines by Space
           Vector Control
    • Authors: Giacomo Sala;Giorgio Valente;David Gerada;Pericle Zanchetta;Chris Gerada;
      Pages: 4168 - 4177
      Abstract: In this article, a novel post fault control algorithm based on the space vector method is presented and applied to a bearingless multisector permanent magnet synchronous machine with a triple three-phase winding. First, the expressions of the current space vectors, as a function of the electromagnetic suspension force and motoring torque, are introduced. Then, the open-circuit fault is described and a new post-fault algorithm is introduced. The introduced post-fault algorithm, based on the minimization of the stator copper losses, is compared at simulation level with an existing one, where the above-mentioned loss minimization was not considered. The simulation results show a remarkable improvement in the performance when the novel post-fault algorithm is employed. Finally, the developed control algorithm is experimentally validated on a prototype of a bearingless multisector permanent magnet synchronous machine.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • An Agile Supply Modulator With Improved Transient Performance for Power
           Efficient Linear Amplifier Employing Envelope Tracking Techniques
    • Authors: Suraj Prakash;Herminio Martínez-García;Mohammad H. Naderi;Hoi Lee;Jose Silva-Martinez;
      Pages: 4178 - 4191
      Abstract: This article presents an agile supply modulator with optimal transient performance that includes improvement in rise time, overshoot and settling time for the envelope tracking supply in linear power amplifiers. For this purpose, we propose an on-demand current source module: the bang–bang transient performance enhancer (BBTPE). Its objective is to follow fast variations in input signals with reduced overshoot and settling time without deteriorating the steady-state performance of the buck regulator. The proposed approach enables fast system response through the BBTPE and an accurate steady-state output response through a low switching ripple and power efficient dynamic buck regulator. Fast output response with the help of the added module induces a slower rise of inductor current in the buck converter that further helps the proposed system to reduce both overshoot and settling time. This article also introduces an efficient selective tracking of envelope signal for linear PAs. To demonstrate the feasibility of the proposed solution, extensive simulations and experimental results from a discrete system are reported. The proposed supply modulator shows 80% improvement in rise time along with 60% reduction in both overshoot and settling time compared to the conventional dynamic buck regulator-based solution. Experimental results using the LTE 16-QAM 5 MHz standard shows improvement of 7.68 dB and 65.1% in adjacent channel power ratio (ACPR) and error vector magnitude (EVM), respectively.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A Simplified Space Vector Pulsewidth Modulation Scheme for Three-Phase
           Cascaded H-Bridge Inverters
    • Authors: Xiajie Wu;Chenglin Xiong;Shunfeng Yang;Hao Yang;Xiaoyun Feng;
      Pages: 4192 - 4204
      Abstract: A simplified space vector pulsewidth modulation (SVPWM) for three-phase cascaded H-bridge (CHB) inverters is presented in this article. Treating each unit as a three-level inverter and adopting serial calculation mode, a CHB inverter is modulated unit by unit using three-level SVPWM. Duty cycles of real sector are obtained by mapping duty cycles of sector 1, in which the calculation of three-level SVPWM is done. The process of implementing multilevel SVPWM is simplified to the process of implementing three-level SVPWM. By reusing field-programmable gate array (FPGA) chip resource that is used for the calculation of three-level SVPWM, the presented SVPWM can be easily adopted for a CHB inverter with different number of units, while the FPGA chip resource utilization is reduced significantly. In addition, the presented SVPWM provides an effective switching frequency higher than the switching frequency of IGBTs. Simulation and experimental results are provided to verify the feasibility of the presented SVPWM.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Thermal Stress Based Power Routing of Smart Transformer With CHB and DAB
           Converters
    • Authors: Vivek Raveendran;Markus Andresen;Giampaolo Buticchi;Marco Liserre;
      Pages: 4205 - 4215
      Abstract: The smart transformer (ST) is a potential solution for an upgrade of the electric distribution grid, which enables to provide services to the grid and dc connectivity. However, the power electronics within the system are challenged by high reliability requirements. One possible solution to increase the reliability is to employ prognosis to predict the failures and avoid down times of the system. Traditional maintenance scheduling is based on the remaining useful lifetime (RUL) of the individual components or the forecasted failure probability. For a further increase of the time to the next maintenance, it is desired to have similar wear out of all components, which need to be maintained or exchanged. In this article, it is proposed to route the power internally in a modular power converter consisting of a cascaded H-bridge connected to dual active bridges in order to influence the RUL of its building blocks. Therefore, a thermal stress based wear-out control is designed for addressing the processed power dependent failures of the devices in the building blocks of the ST. Compared to the conventional power routing methods, the impact of the proposed system-level control considering electrical and thermal parameter variations is demonstrated using Monte Carlo analysis.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Direct Torque Control for Three-Phase Open-End Winding PMSM With Common DC
           Bus Based on Duty Ratio Modulation
    • Authors: Xiaogang Lin;Wenxin Huang;Wen Jiang;Yong Zhao;Dingfeng Dong;Xu Wu;
      Pages: 4216 - 4232
      Abstract: This article introduces the classical direct torque control (DTC) to a three-phase open-end winding permanent magnet synchronous motor with common dc bus for the first time. The electromagnetic torque and the stator flux are controlled at the same time. However, the zero-sequence current is not suppressed, and the ripples of the electromagnetic torque and stator flux are large. To improve the operation performance of this drive system, a DTC based on a duty ratio modulation (DRM-DTC) is proposed. First, a deadbeat zero-sequence current controller is proposed in the DRM-DTC to suppress the zero-sequence current. Second, another strategy, which is based on a graphical analysis method and a simple deadbeat direct torque and flux controller, is proposed to optimize the duty ratio of the active voltage vector. Thus, the electromagnetic torque and stator flux ripples can be reduced. Finally, an optimized pulsewidth modulation implementation strategy is proposed in the DRM-DTC to further reduce the switching frequency of inverters. The classical DTC and the proposed DRM-DTC are compared through simulation and experiment, and the results verify the effectiveness of the proposed strategy.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Sigmoid Function Model for a PFM Power Electronic Converter
    • Authors: Yimin Lu;Xianfeng Huang;Yizheng Huang;Dong Liu;
      Pages: 4233 - 4241
      Abstract: A power electronic converter is a switching system; the key to modeling it is how to describe the interaction between the discrete switch variables and the continuous state variables in a unified model. A power electronic converter modeling method based on sigmoid functions is proposed. Since the sigmoid function is continuous, smooth, differentiable, and saturated at a certain value, a sigmoid function with a large steepness factor is used to approximate the switching process of the switch; the converter is transformed from a switching system to a continuous system so that nonlinear continuous system analysis and design methods can be directly applied to the converter control system. Sigmoid function equivalent circuit models for several typical inverter and rectifier circuits are provided. A half-bridge LLC resonant converter is selected as an example, and its sigmoid function model is constructed and subsequently validated through simulation and experimentation. The results show that the constructed model is in good agreement with the circuit simulation and experimental results. The mathematical expression of the model has a simple and unified structure and definite physical meaning and is a high-accuracy large-signal continuous model with universal significance.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Active Thermal Control for Hybrid Modular Multilevel Converter Under
           Overmodulation Operation
    • Authors: Jing Sheng;Heya Yang;Chushan Li;Min Chen;Wuhua Li;Xiangning He;Xiaowei Gu;
      Pages: 4242 - 4255
      Abstract: The thermal management plays an important role in improving the reliability and lifetime of high power converters, especially for the high voltage direct current (HVdc) transmission system. In the voltage source converter based HVdc systems (VSC-HVdc), the hybrid modular multilevel converters (MMCs) are taken as the excellent candidates due to their dc short-circuit fault ride-through ability and less submodule (SM) devices. Furthermore, the voltage modulation index of hybrid MMCs can be promoted to achieve higher power rating and efficiency. However, in this article, it is revealed that thermal stress distribution inside the SMs becomes more unbalanced under a high voltage modulation index, which would lead to serious thermal fatigue. To overcome this problem, the active bypass with thyristor for half-bridge submodules (HBSMs) and symmetrical modulation for full-bridge submodules (FBSMs) based active thermal control strategies are employed. With the presented thermal control strategies, the junction temperature of the most stressed devices in both HBSMs and FBSMs is reduced enormously. Besides, the thermal control strategy does not bring negative influence on the steady-state output performance of hybrid MMC. Finally, the theoretical analysis and effectiveness of the proposed control methods are verified based on a laboratorial MMC prototype.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Communication-Independent Power Balance Control for Solid State
           Transformer Interfaced Multiple Power Conversion Systems
    • Authors: Jintong Nie;Liqiang Yuan;Wusong Wen;Renzhi Duan;Bingqing Shi;Zhengming Zhao;
      Pages: 4256 - 4271
      Abstract: A coordinated power balance control strategy independent of communication is proposed in this article, which includes autonomous modes transition control methods for photovoltaic converter, battery energy storage system and their cooperation with solid state transformer. The synthesized multiple power conversion systems contain an internal dc point-of-common coupling (PCC) and an external ac PCC, which form a dc microgrid and an ac microgrid, respectively. In grid-connected mode, the system is able to operate in power regulation pattern corresponding to grid-side response, or secondary dc bus voltage regulation pattern corresponding to local loads response, and switch between them on demand. Grid-connected and islanded/standalone modes can be transferred seamlessly, without the need of control structure reconfiguration through communication links. Moreover, control-related real-time communication is no longer necessary in this scheme, thus improving the reliability and reducing the total costs accordingly. Experimental results are provided to validate the effectiveness of the proposed control scheme.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Phase-Locked Loop Combined With Chained Trigger Mode Used for Impedance
           Matching in Wireless High Power Transfer
    • Authors: Yongbin Jiang;Laili Wang;Yue Wang;Min Wu;Zexian Zeng;Yonghui Liu;Jing Sun;
      Pages: 4272 - 4285
      Abstract: In a wireless power transfer system (WPTS), the control technique of the active rectifier is vital for improving the transfer efficiency of the resonant network, expanding the operating range of the load, and increasing the power density. An indispensable component of such control technique is the accurate and reliable phase-locked method for the resonant current. However, the traditional phase-locked method based on the DSP controller tends to lose driver pulses, which might cause damage to the safe operation of the WPTS. This article illustrates the essential reason why the driver pulses lose and proposes a phase-locked loop combined with the chained trigger mode (PLL-CTM) that can lock the phase of the resonant current accurately and produce the driver pulses reliably. With the proposed PLL-CTM applied, the reliability of the WPTS can be enhanced tremendously. Furthermore, based on the PLL-CTM, this article also presents a double-side phase shift control (DPSC) strategy to achieve constant-current constant-voltage charging and minimize the power loss of the resonant network simultaneously. Finally, a 500-W WPT prototype is built to verify the feasibility of the DPSC with PLL-CTM. Benefiting from the DPSC with PLL-CTM, the WPTS not only obtains a high accuracy in steady state, but also achieves a good dynamic performance with the step change of ${R_{{{rm L}}}}$ and ${R_{{rm {Eref}}}}$.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Decoupling of Current Balancing and Reference Tracking Control in Parallel
           Interleaved Converters
    • Authors: Dejan P. Jovanović;Mark A. H. Broadmeadow;Richard R. Taylor;Geoffrey R. Walker;Gerard F. Ledwich;
      Pages: 4286 - 4295
      Abstract: An attractive approach to increasing the output power and bandwidth of converters is through the parallel connection of multiple, subrated converter cells via mutually coupled inductors. Achieving a balanced contribution to the output current by all paralleled converter cells is critical; good reference tracking performance, however, should also be maintained. Since these two control tasks are coupled, tuning of the controller parameters is challenging. This article demonstrates a methodology for decoupling the output current reference tracking control task from the current balancing control. We show that once balancing and tracking controllers are decoupled, the controller parameter tuning can be conducted independently, simplifying design and analysis of controller performance. Experimental results are presented, which validate the proposed methodology, applied to a three-cell, parallel interleaved converter with cyclic cascade coupled inductor filter network, operating at 100 ${rm V}_{rm RMS}$ and 9 ${rm A}_{rm RMS}$.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Improved Modulation Strategy for Single-Phase Isolated Quasi-Single-Stage
           AC–DC Converter to Improve Current Characteristics
    • Authors: Xiaoguang Li;Fengjiang Wu;Guijie Yang;Hongchen Liu;
      Pages: 4296 - 4308
      Abstract: In this article, an improved triple-phase-shift (ITPS) modulation for the single-phase isolated quasi-single-stage ac–dc converter is proposed to realize the current decouple between the adjacent switching periods and to reduce the grid current distortion. Moreover, the dead band effect on the proposed ITPS is analyzed for the first time. It reveals that the dead band causes not only the current couple and accordingly the grid current distortion but also the current amplitude loss. A two-step phase-shift compensation scheme is proposed based on the analysis result to solve the problems caused by the dead band. All of the theoretical analysis, the proposed ITPS modulation, and the dead band compensation scheme are validated in detail in the experimental way.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • A Hybrid Modulation Strategy Providing Lower Inductor Current for the DAB
           Converter With the Aid of DC Blocking Capacitors
    • Authors: Peng Liu;Shanxu Duan;
      Pages: 4309 - 4320
      Abstract: For the dual active bridge converter, the single phase shift (SPS) modulation strategy is simple and effective for controlling the transmission power. However, when the voltage varies widely, it is hard to realize soft switching and the circulating power increases dramatically, which results in the increased current stress and reduced efficiency. Thus, a hybrid modulation strategy is proposed in this article, whose main idea is to introduce a voltage offset across the dc blocking capacitors in both sides, and the converter can switch between different operating modes to lower the inductor current according to different operating conditions. Operational principle of the proposed modulation is introduced, and the normalized root-mean-square values of the inductor current in different working modes are derived mathematically, which leads to the selection criterion among different operating modes. The proposed scheme retains the simplicity of the conventional SPS strategy and improves the efficiency over wide voltage range and wide load range without complicating the topology structure. Finally, the performance of the proposed modulation is verified by the experimental results.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Inertia Response Improvement in AC Microgrids: A Fuzzy-Based Virtual
           Synchronous Generator Control
    • Authors: Amin Karimi;Yousef Khayat;Mobin Naderi;Tomislav Dragičević;Rahmatollah Mirzaei;Frede Blaabjerg;Hassan Bevrani;
      Pages: 4321 - 4331
      Abstract: The absence of rotational masses from synchronous generators in converter-interfaced microgrids leads to a lack of inertia. Consequently, the system exhibits steeper frequency variations and higher frequency nadir, which may degrade the dynamic performance and challenge the operation of sensitive equipment such as protective relays in the grid. Virtual synchronous generator is introduced as an effective solution to increase the inertial response of converter interfaced renewable energy sources. This article proposed a fuzzy controller, which is augmented on the virtual synchronous generator topology to damp the perturbation during transients by increasing the inertia of the system. The proposed fuzzy control adds a correction term to the governor's output power that increases the system inertia during transients. In order to compare the inertial response improvement, a comparison between proposed fuzzy control technique and cost function based inertia and damping coefficient optimization is done on a virtual synchronous generator platform. It is shown that online measurement based adaptive methods have a better inertial response against other time-consuming techniques. To further verification, a number of experiments are done, which confirm the merits of the proposed fuzzy based virtual synchronous generator control method.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Control Method for Avoiding Transformer Saturation in High-Power
           Three-Phase Dual-Active Bridge DC–DC Converters
    • Authors: Johannes Voss;Stefan P. Engel;Rik W. De Doncker;
      Pages: 4332 - 4341
      Abstract: The classic top to down structure of electrical infrastructure is changing due to the extensive spread of renewable energy sources which are connected to medium-voltage and low-voltage grids. Especially for medium-voltage direct-current grids, the three-phase dual-active bridge (DAB) dc–dc converter is one of the most promising converter topologies, as it features bidirectional power flow and galvanic isolation at highest efficiency. Unwanted saturation of the transformer of this converter can occur, particularly for multimegawatt converters with highly efficient, low-loss transformers. The saturation leads to additional core losses, elevated voltage stress at the windings, and increased magnetostriction of the transformer core, which can result in undesired acoustic emissions. The following article presents a feedback control and modulation method that controls the DAB converter such that saturation of the transformer is avoided. The chosen approach evaluates the star-point voltage of the transformer to determine the dc component of the magnetizing current, thereby avoiding the need for expensive high-precision current sensors. The control method is analytically derived and verified by simulation. Experiments carried out using a 5 MW medium-voltage three-phase DAB converter prototype verify the presented modulation method.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Enabling Grid-Feeding Converters With a Dissonant-Resonant Controller for
           Negative-Sequence Voltage Elimination
    • Authors: Manel Velasco;Pau Martí;Antonio Camacho;Juan M. Rey;Jaume Miret;Miguel Castilla;
      Pages: 4342 - 4352
      Abstract: The mitigation of the adverse effects of voltage unbalance in equipment and power quality can be performed by the power electronic converters that interface distributed generators to the grid. Inspired in a resonant controller, this article presents a dissonant-resonant controller for negative-sequence voltage elimination for a grid-feeding converter connected to the grid. The controller eliminates the negative-sequence voltage at the converter output with a regulable precision, it does not require knowing the grid impedance for successful operation, and it can be a good candidate for parallel operation because it operates not like an integrator, but like an “untuned” integrator. Using the stationary $alpha beta$ frame, a closed-loop model is developed in a complex space vector built from the complexification of the stationary components. This allows extracting stability conditions for safe closed-loop operation as well as deriving design guidelines for the controller parameters. Numerical and experimental results show the ability of the proposed controller to meet its design goals, thus, corroborating the theoretical approach.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • $2omega$ -Ripple+and+Uncertainty,+and+Improvement+in+Dynamic+Performance&rft.title=IEEE+Transactions+on+Power+Electronics&rft.issn=0885-8993&rft.date=2020&rft.volume=35&rft.spage=4353&rft.epage=4364&rft.aulast=Rathore;&rft.aufirst=Aditya&rft.au=Aditya+R.+Gautam;Deepak+Fulwani;Rammohan+R.+Makineni;Nupur+Rathore;">ISMC for Boost-Derived DC–DC–AC Converter: Mitigation of
           $2omega$ -Ripple and Uncertainty, and Improvement in Dynamic Performance
    • Authors: Aditya R. Gautam;Deepak Fulwani;Rammohan R. Makineni;Nupur Rathore;
      Pages: 4353 - 4364
      Abstract: In controller design, the classical control techniques have their distinct advantages and capabilities. The integral sliding-mode control (ISMC) leverages the merits of such control techniques by allowing their merger with the sliding-mode control (SMC). ISMC is composed of two components, a nominal control designed using any methodology and a discontinuous-SMC, and thus the system can have specified performance with high degree of robustness. The proposed work achieves multiple objectives, i.e., mitigates $2omega$-ripple, ensures robustness, and improves dynamic performance. The proposed ISM-based controller amalgamates SMC with a new dual-loop adaptive PID-control (as the nominal control). The discontinuous-SMC part ensures robustness against the matched-uncertainty, i.e., disturbances entering through the input channel such as parametric variations, exogenous disturbances, modeling-error, and the nominal control mitigate $2omega$-ripple at the input of dc–dc–ac converter. Moreover, the adaptive nature of nominal control improves the system performance at the large line-load transients unlike the conventional control. Furthermore, the proposed controller supports the reduction of $2omega$-ripple at the input of converter. The proposed control scheme is validated using 1-kW prototype.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Online Impedance Measurement of Batteries Using the Cross-Correlation
           Technique
    • Authors: Taha Nurettin Gücin;Levent Ovacik;
      Pages: 4365 - 4375
      Abstract: Electrochemical impedance spectroscopy (EIS) is a powerful test technique that is extensively applied to electrochemical cells for determining the frequency response of the cell impedance. The results from EIS may be used for many applications, such as state of charge (SOC) and state of health. This article presents an approach for online EIS based on cross-correlation technique applied to a boost-type dc–dc charge controller for batteries. The theoretical background is explained and some improvements specific to battery applications are suggested. Preparation of noise datasets, postprocessing of results, and model fitting of the measurements are discussed in detail. The validity of the approach is experimentally confirmed with a digitally controlled boost converter that is charging a 12-V, 7-Ah sealed lead-acid battery: First, the perturbation magnitude is determined experimentally and then the battery is tested via the proposed method at 50% SOC. It is shown that the results of the present approach coincide with those obtained by a commercially available, laboratory-type, high-precision instruments. Finally, the tests were also repeated for 25% and 75% SOC values. It is shown that the proposed approach can be reliably used to analyze the impedance of batteries over a wide frequency range during battery charging process.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Active Saturation Mitigation in High-Density Dual-Active-Bridge DC–DC
           Converter for On-Board EV Charger Applications
    • Authors: Seyed Amir Assadi;Hirokazu Matsumoto;Mazhar Moshirvaziri;Miad Nasr;Mohammad Shawkat Zaman;Olivier Trescases;
      Pages: 4376 - 4387
      Abstract: This article presents a transformer saturation prevention algorithm (SPA) targeting dual-active-bridge (DAB) dc–dc converters utilized in bidirectional, two-stage electric vehicle (EV) on-board battery chargers. Saturation prevention is achieved by detecting the variation in transformer current slope near the boundary of saturation and applying duty-cycle offsets to the DAB converter full bridges. Compared to alternative methods of saturation mitigation, the proposed algorithm offers the following benefits: Lower transformer design safety margins which enable volume reduction with minimal harm to efficiency, and low-cost implementation using a single low-cost current sensor even at high converter switching speeds. Experiments on a custom 6.6-kW on-board EV charger confirm the controller functionality and initial converter analysis. A peak converter efficiency of 96.8% with a transformer volume of 80 cm$^3$ is achieved, which is a 50% volume reduction in comparison to other academic works.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Impedance-Based Stability Analysis for Interconnected Converter Systems
           With Open-Loop RHP Poles
    • Authors: Yicheng Liao;Xiongfei Wang;
      Pages: 4388 - 4397
      Abstract: The small-signal stability of interconnected converter systems can be tackled by the impedance-based analysis method, where the Bode plots of the individual impedances derived from subsystems are utilized for a design-oriented analysis. However, those methods only apply to the interconnected systems without having open-loop right-half-plane (RHP) poles. This article thus proposes a general stability analysis method based on Bode plots of individual impedances, which allows considering the open-loop RHP poles and shaping the impedances for stabilizing the system. Experimental case studies on the current control interactions of two paralleled grid-tied inverters validate the effectiveness of the method.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • The Electronic Realization of Synchronous Machines: Model Matching, Angle
           Tracking, and Energy Shaping Techniques
    • Authors: Catalin Arghir;Florian Dörfler;
      Pages: 4398 - 4410
      Abstract: In this article, we investigate grid-forming and grid-following control strategies starting from a nonlinear state-space modeling viewpoint. An electronic synchronous machine is an inverter whose integral of the dc-bus measurement generates the angle of the instantaneous modulation vector. We show how this minimal augmentation constitutes an exact physical realization without requiring inner-current loops. The dc-link capacitance becomes the equivalent rotational inertia of the converter. Additional features, such as a phase locked loop, a voltage controller, and a power tracking mechanism are then designed via two energy-shaping techniques. One energy function is used to implement a grid-following control scheme, via the inherent synchronizing torque, while the other is used to implement a grid-forming control scheme. An alternative interpretation of active-power droop is suggested by this method. The results are first derived systematically, and then evaluated experimentally on a front-to-front setup.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Modeling, Analysis, and Reduction of Harmonics in Paralleled and
           Interleaved Three-Level Neutral Point Clamped Inverters With Space Vector
           Modulation
    • Authors: Ruirui Chen;Jiahao Niu;Handong Gui;Zheyu Zhang;Fei Wang;Leon M. Tolbert;Daniel J. Costinett;Benjamin J. Blalock;Benjamin B. Choi;
      Pages: 4411 - 4425
      Abstract: Paralleling three phase three-level inverters is gaining popularity in industrial applications. However, analytical models for the harmonics calculation of a three-level neutral point clamped (NPC) inverter with popular space vector modulation (SVM) are not found in the literature. Moreover, how interleaving angle impacts the dc- and ac-side harmonics and electromagnetic interference (EMI) harmonics in parallel interleaved three-level inverters and how to optimize interleaving angle to reduce these harmonics have not been discussed in the literature. Furthering previous study, this article presents the modeling, analysis, and reduction of harmonics in paralleled and interleaved three-level NPC inverters with SVM. Analytical models for harmonic calculation are developed, and the dc-side harmonics characteristics of an NPC inverter are identified. The impact of interleaving angle on the ac-side voltage and dc-link current harmonics of parallel interleaved three-level NPC inverters is comprehensively studied. The impact of switching frequency and interleaving angle on EMI harmonics is also illustrated. Optimal interleaving angle ranges to reduce these harmonics are derived analytically. The developed models and harmonic reduction analysis are verified experimentally with two paralleled and interleaved three-level NPC inverters.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Feedforward Modulation for the Neutral-Point-Clamped Converter With
           Confined Capacitor Voltage Ripples and Reduced Switching Power Losses
    • Authors: Neha Beniwal;Josep Pou;Salvador Ceballos;Christopher David Townsend;Georgios Konstantinou;Hossein Dehghani Tafti;Glen Ghias Farivar;
      Pages: 4426 - 4438
      Abstract: This article presents a new modulation technique with feedforward compensation for the three-phase three-level neutral-point-clamped converter. With the proposed technique, the capacitor voltage ripples are allowed to vary within certain limits. This enables an optimized design of the converter since the maximum capacitor voltages are predefined. Furthermore, the proposed modulation technique is able to reduce switching power losses compared to modulation techniques that eliminate capacitor voltage ripples completely. The proposed technique is therefore a tradeoff solution between aforementioned techniques and traditional modulation techniques where the capacitor voltage ripples are not limited. In the proposed technique, if the capacitor voltages are within the tolerable specified range, all the phases switch in two consecutive voltage levels in steady state. When the capacitor voltages go beyond the specified limits, one of the three phases is chosen to switch in three levels to inject an appropriate neutral point current for capacitor voltage balance. As the capacitor voltages are allowed to oscillate, the modulation technique is provided with feedforward compensation to avoid producing low-frequency distortion on the output voltages of the converter. Experimental results are presented operating under different loading conditions.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Combined State and Parameter Estimation of Lithium-Ion Battery With Active
           Current Injection
    • Authors: Ziyou Song;Hao Wang;Jun Hou;Heath F. Hofmann;Jing Sun;
      Pages: 4439 - 4447
      Abstract: Estimating the State-of-Charge (SoC) and State-of-Health (SoH), together with the parameters used in representing the dynamics of a lithium-ion battery, is essential to ensure optimal and reliable operation. However, this simultaneous estimation can take a significant amount of time to converge, and the estimation accuracy is limited by measurement noise and model inaccuracy. Note that for overactuated systems (e.g., hybrid energy storage systems and hybrid electric vehicles), the overactuation feature can be exploited to optimize the battery current profile for the estimation purpose. This article shows the potential to improve estimation accuracy when the desired current is actively injected and the estimation algorithm is properly structured. Specifically, by incorporating a high-pass filter, battery parameters can be independently characterized by injecting high-frequency and medium-frequency currents, and battery SoC/SoH can then be estimated sequentially from the estimated parameters. A Cramer–Rao bound analysis shows that the accuracy of the proposed sequential estimation is much better than the case where all parameters and states are simultaneously estimated. The analysis is verified by simulation and experimental results. We point out that for battery-only applications (e.g., electric vehicles); the proposed method has limitations, as generally, the battery current profile cannot be changed.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
  • Comments on “State of Charge-Dependent Polynomial Equivalent Circuit
           Modeling for Electrochemical Impedance Spectroscopy of Lithium-Ion
           Batteries”
    • Authors: Rahat Hasan;Jonathan Scott;
      Pages: 4448 - 4448
      Abstract: A recent paper by Wang et al. [ibid., vol. 33, no. 10, pp. 8449–8460, Oct. 2018] proposes a state of a charge-dependent polynomial equivalent circuit model for lithium batteries. The model consists of an inductor, a Warburg element, a constant phase element (CPE), and two resistors. The authors quote the impedance equation of a Warburg element, where τ is the diffusion time constant, ϕ varies between 0 and 1, and RW is the Warburg resistance. This equation is wrong; in a Nyquist plot, the angle in a Warburg element is fixed to 45° at high frequencies, corresponding to ϕ = 0.5. Such behavior is a result of diffusion through a semi-infinite medium. The frequency band where it is observed is called the Warburg region. The correct form of the impedance equation of a Warburg element is provided.
      PubDate: April 2020
      Issue No: Vol. 35, No. 4 (2020)
       
 
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