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  Subjects -> ELECTRONICS (Total: 207 journals)
Showing 1 - 200 of 277 Journals sorted alphabetically
Acta Electronica Malaysia     Open Access  
Advanced Materials Technologies     Hybrid Journal   (Followers: 1)
Advances in Biosensors and Bioelectronics     Open Access   (Followers: 8)
Advances in Electrical and Electronic Engineering     Open Access   (Followers: 9)
Advances in Electronics     Open Access   (Followers: 100)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Microelectronic Engineering     Open Access   (Followers: 13)
Advances in Power Electronics     Open Access   (Followers: 41)
Advancing Microelectronics     Hybrid Journal  
American Journal of Electrical and Electronic Engineering     Open Access   (Followers: 28)
Annals of Telecommunications     Hybrid Journal   (Followers: 8)
APSIPA Transactions on Signal and Information Processing     Open Access   (Followers: 8)
Archives of Electrical Engineering     Open Access   (Followers: 16)
Australian Journal of Electrical and Electronics Engineering     Hybrid Journal  
Batteries     Open Access   (Followers: 9)
Batteries & Supercaps     Hybrid Journal   (Followers: 5)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 31)
Bioelectronics in Medicine     Hybrid Journal  
Biomedical Instrumentation & Technology     Hybrid Journal   (Followers: 6)
BULLETIN of National Technical University of Ukraine. Series RADIOTECHNIQUE. RADIOAPPARATUS BUILDING     Open Access   (Followers: 2)
Bulletin of the Polish Academy of Sciences : Technical Sciences     Open Access   (Followers: 1)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 46)
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: 310)
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: 124)
Electronic Markets     Hybrid Journal   (Followers: 7)
Electronic Materials Letters     Hybrid Journal   (Followers: 4)
Electronics     Open Access   (Followers: 109)
Electronics and Communications in Japan     Hybrid Journal   (Followers: 10)
Electronics For You     Partially Free   (Followers: 104)
Electronics Letters     Hybrid Journal   (Followers: 26)
Elektronika ir Elektortechnika     Open Access   (Followers: 2)
Elkha : Jurnal Teknik Elektro     Open Access  
Emitor : Jurnal Teknik Elektro     Open Access   (Followers: 3)
Energy Harvesting and Systems     Hybrid Journal   (Followers: 4)
Energy Storage     Hybrid Journal   (Followers: 1)
Energy Storage Materials     Full-text available via subscription   (Followers: 4)
EPE Journal : European Power Electronics and Drives     Hybrid Journal  
EPJ Quantum Technology     Open Access   (Followers: 1)
EURASIP Journal on Embedded Systems     Open Access   (Followers: 11)
Facta Universitatis, Series : Electronics and Energetics     Open Access  
Foundations and Trends® in Communications and Information Theory     Full-text available via subscription   (Followers: 6)
Foundations and Trends® in Signal Processing     Full-text available via subscription   (Followers: 9)
Frequenz     Hybrid Journal   (Followers: 1)
Frontiers of Optoelectronics     Hybrid Journal   (Followers: 1)
IACR Transactions on Symmetric Cryptology     Open Access   (Followers: 1)
IEEE Antennas and Propagation Magazine     Hybrid Journal   (Followers: 103)
IEEE Antennas and Wireless Propagation Letters     Hybrid Journal   (Followers: 81)
IEEE Embedded Systems Letters     Hybrid Journal   (Followers: 57)
IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology     Hybrid Journal   (Followers: 3)
IEEE Journal of Emerging and Selected Topics in Power Electronics     Hybrid Journal   (Followers: 52)
IEEE Journal of the Electron Devices Society     Open Access   (Followers: 9)
IEEE Journal on Exploratory Solid-State Computational Devices and Circuits     Hybrid Journal   (Followers: 1)
IEEE Letters on Electromagnetic Compatibility Practice and Applications     Hybrid Journal   (Followers: 4)
IEEE Magnetics Letters     Hybrid Journal   (Followers: 7)
IEEE Nanotechnology Magazine     Hybrid Journal   (Followers: 42)
IEEE Open Journal of Circuits and Systems     Open Access   (Followers: 3)
IEEE Open Journal of Industry Applications     Open Access   (Followers: 3)
IEEE Open Journal of the Industrial Electronics Society     Open Access   (Followers: 3)
IEEE Power Electronics Magazine     Full-text available via subscription   (Followers: 77)
IEEE Pulse     Hybrid Journal   (Followers: 5)
IEEE Reviews in Biomedical Engineering     Hybrid Journal   (Followers: 23)
IEEE Solid-State Circuits Letters     Hybrid Journal   (Followers: 3)
IEEE Solid-State Circuits Magazine     Hybrid Journal   (Followers: 13)
IEEE Transactions on Aerospace and Electronic Systems     Hybrid Journal   (Followers: 371)
IEEE Transactions on Antennas and Propagation     Full-text available via subscription   (Followers: 74)
IEEE Transactions on Automatic Control     Hybrid Journal   (Followers: 64)
IEEE Transactions on Autonomous Mental Development     Hybrid Journal   (Followers: 8)
IEEE Transactions on Biomedical Engineering     Hybrid Journal   (Followers: 39)
IEEE Transactions on Broadcasting     Hybrid Journal   (Followers: 13)
IEEE Transactions on Circuits and Systems for Video Technology     Hybrid Journal   (Followers: 26)
IEEE Transactions on Consumer Electronics     Hybrid Journal   (Followers: 46)
IEEE Transactions on Electron Devices     Hybrid Journal   (Followers: 19)
IEEE Transactions on Geoscience and Remote Sensing     Hybrid Journal   (Followers: 228)
IEEE Transactions on Haptics     Hybrid Journal   (Followers: 5)
IEEE Transactions on Industrial Electronics     Hybrid Journal   (Followers: 75)
IEEE Transactions on Industry Applications     Hybrid Journal   (Followers: 40)
IEEE Transactions on Information Theory     Hybrid Journal   (Followers: 27)
IEEE Transactions on Learning Technologies     Full-text available via subscription   (Followers: 12)
IEEE Transactions on Power Electronics     Hybrid Journal   (Followers: 80)
IEEE Transactions on Services Computing     Hybrid Journal   (Followers: 4)
IEEE Transactions on Signal and Information Processing over Networks     Hybrid Journal   (Followers: 13)
IEEE Transactions on Software Engineering     Hybrid Journal   (Followers: 79)
IEEE Women in Engineering Magazine     Hybrid Journal   (Followers: 11)
IEEE/OSA Journal of Optical Communications and Networking     Hybrid Journal   (Followers: 16)
IEICE - Transactions on Electronics     Full-text available via subscription   (Followers: 12)
IEICE - Transactions on Information and Systems     Full-text available via subscription   (Followers: 5)
IET Cyber-Physical Systems : Theory & Applications     Open Access   (Followers: 1)
IET Energy Systems Integration     Open Access   (Followers: 1)
IET Microwaves, Antennas & Propagation     Hybrid Journal   (Followers: 36)
IET Nanodielectrics     Open Access  
IET Power Electronics     Hybrid Journal   (Followers: 61)
IET Smart Grid     Open Access   (Followers: 1)
IET Wireless Sensor Systems     Hybrid Journal   (Followers: 18)
IETE Journal of Education     Open Access   (Followers: 4)
IETE Journal of Research     Open Access   (Followers: 11)
IETE Technical Review     Open Access   (Followers: 13)
IJEIS (Indonesian Journal of Electronics and Instrumentation Systems)     Open Access   (Followers: 3)
Industrial Technology Research Journal Phranakhon Rajabhat University     Open Access  
Informatik-Spektrum     Hybrid Journal   (Followers: 2)
Instabilities in Silicon Devices     Full-text available via subscription   (Followers: 1)
Intelligent Transportation Systems Magazine, IEEE     Full-text available via subscription   (Followers: 14)
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: 38)
Journal of Electrical Bioimpedance     Open Access  
Journal of Electrical Bioimpedance     Open Access   (Followers: 2)
Journal of Electrical Engineering & Electronic Technology     Hybrid Journal   (Followers: 7)
Journal of Electrical, Electronics and Informatics     Open Access  
Journal of Electromagnetic Analysis and Applications     Open Access   (Followers: 8)
Journal of Electromagnetic Waves and Applications     Hybrid Journal   (Followers: 9)
Journal of Electronic Design Technology     Full-text available via subscription   (Followers: 6)
Journal of Electronic Science and Technology     Open Access   (Followers: 1)
Journal of Electronics (China)     Hybrid Journal   (Followers: 5)
Journal of Energy Storage     Full-text available via subscription   (Followers: 4)
Journal of Engineered Fibers and Fabrics     Open Access   (Followers: 2)
Journal of Field Robotics     Hybrid Journal   (Followers: 4)
Journal of Guidance, Control, and Dynamics     Hybrid Journal   (Followers: 191)
Journal of Information and Telecommunication     Open Access   (Followers: 1)
Journal of Intelligent Procedures in Electrical Technology     Open Access   (Followers: 3)
Journal of Low Power Electronics     Full-text available via subscription   (Followers: 10)
Journal of Low Power Electronics and Applications     Open Access   (Followers: 10)
Journal of Microelectronics and Electronic Packaging     Hybrid Journal   (Followers: 1)
Journal of Microwave Power and Electromagnetic Energy     Hybrid Journal   (Followers: 3)
Journal of Microwaves, Optoelectronics and Electromagnetic Applications     Open Access   (Followers: 11)
Journal of Nuclear Cardiology     Hybrid Journal  
Journal of Optoelectronics Engineering     Open Access   (Followers: 4)
Journal of Physics B: Atomic, Molecular and Optical Physics     Hybrid Journal   (Followers: 32)
Journal of Power Electronics     Hybrid Journal   (Followers: 2)
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: 27)
Journal of Signal and Information Processing     Open Access   (Followers: 8)
Jurnal ELTIKOM : Jurnal Teknik Elektro, Teknologi Informasi dan Komputer     Open Access  
Jurnal Rekayasa Elektrika     Open Access  
Jurnal Teknik Elektro     Open Access  
Jurnal Teknologi Elektro     Open Access  
Kinetik : Game Technology, Information System, Computer Network, Computing, Electronics, and Control     Open Access  
Majalah Ilmiah Teknologi Elektro : Journal of Electrical Technology     Open Access   (Followers: 2)
Metrology and Measurement Systems     Open Access   (Followers: 6)
Microelectronics and Solid State Electronics     Open Access   (Followers: 28)
Nanotechnology, Science and Applications     Open Access   (Followers: 6)
Nature Electronics     Hybrid Journal   (Followers: 1)
Networks: an International Journal     Hybrid Journal   (Followers: 4)
Open Electrical & Electronic Engineering Journal     Open Access  
Open Journal of Antennas and Propagation     Open Access   (Followers: 8)
Paladyn. Journal of Behavioral Robotics     Open Access   (Followers: 1)
Power Electronics and Drives     Open Access   (Followers: 2)
Problemy Peredachi Informatsii     Full-text available via subscription  
Progress in Quantum Electronics     Full-text available via subscription   (Followers: 7)
Radiophysics and Quantum Electronics     Hybrid Journal   (Followers: 2)
Recent Advances in Communications and Networking Technology     Hybrid Journal   (Followers: 3)
Recent Advances in Electrical & Electronic Engineering     Hybrid Journal   (Followers: 11)
Research & Reviews : Journal of Embedded System & Applications     Full-text available via subscription   (Followers: 6)
Revue Méditerranéenne des Télécommunications     Open Access  
Security and Communication Networks     Hybrid Journal   (Followers: 2)
Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of     Hybrid Journal   (Followers: 57)
Semiconductors and Semimetals     Full-text available via subscription   (Followers: 1)
Sensing and Imaging : An International Journal     Hybrid Journal   (Followers: 2)
Solid State Electronics Letters     Open Access  
Solid-State Electronics     Hybrid Journal   (Followers: 9)
Superconductor Science and Technology     Hybrid Journal   (Followers: 3)
Synthesis Lectures on Power Electronics     Full-text available via subscription   (Followers: 3)
Technical Report Electronics and Computer Engineering     Open Access  
TELE     Open Access  
Telematique     Open Access  
TELKOMNIKA (Telecommunication, Computing, Electronics and Control)     Open Access   (Followers: 10)
Transactions on Cryptographic Hardware and Embedded Systems     Open Access   (Followers: 2)

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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: 80  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0885-8993
Published by IEEE Homepage  [229 journals]
  • IEEE Power Electronics Society
    • Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • IEEE Power Electronics Society
    • Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Administrative Committee
    • Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • $C_{text{oss}}$ +Loss+Tangent+of+Field-Effect+Transistors:+Generalizing+High-Frequency+Soft-Switching+Losses&rft.title=IEEE+Transactions+on+Power+Electronics&rft.issn=0885-8993&rft.date=2020&rft.volume=35&rft.spage=12585&rft.epage=12589">$C_{text{oss}}$ Loss Tangent of Field-Effect Transistors: Generalizing
           High-Frequency Soft-Switching Losses
    • Pages: 12585 - 12589
      Abstract: The dissipated energy ($E_{text{diss}}$) related to the resonant charging–discharging of a transistor output capacitance becomes a dominant loss factor for power converters operating in the MHz range. A recent letter has introduced a small-signal measurement method to quantify $E_{text{diss}}$ with a frequency-dependent small-signal resistance, $R_{text{s}}$, and an effective small-signal output capacitance, $C_{text{oss}}^{text{eff}}$. This letter provides further insights on the effect of $R_{text{s}}$ and $C_{text{oss}}$ upon the device losses in a broader sense. In particular, the $C_{text{oss}}$ loss tangent, tan ($delta$), is introduced as a normalized $E_{text{diss}}$ to combine the roles of $R_{text{s}}$ and $C_{text{oss}}$ together with the operating frequency into a single loss parameter. By evaluating commercial device families, it is demonstrated that tan ($delta$) is constant for a given family, independent of device on-state resistance, $R_{text{DS(on)}}$. It is shown-that a minimum $E_{text{diss}}$ is achieved by having the lowest tan ($delta$) for a given stored energy ($E_{text{oss}}$) in $C_{text{oss}}$. With accompanying guidelines, this letter identifies tan ($delta$) as a powerful figure of merit to classify field-effect transistors (FETs) for soft-switching applications, regardless of $R_{text{DS(on)}}$ variations in devices within a family. The proposed concept provides a comprehensive method to characterize and benchmark field-effect transistors for efficient operation in high and very-high-frequency (VHF) applications.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • A Digital Interconnected Bus Providing Voltage Synchronization for the
           Modular Series-Connected Inverters
    • Pages: 12590 - 12594
      Abstract: The input port or the output port series-connected system is very suitable for medium- or high-voltage applications. For the output series-connected modular inverter system, the important issue is to guarantee that the phase angle of the different modules are exactly the same, otherwise, the total output voltage cannot meet the requirement. This letter proposes a digital synchronization strategy, which adopts a digital interconnected bus to provide the common reference signal for the composed modules. The operation principle, circuit schematic, and control design of the proposed strategy are explained in detail in this letter, and finally, the performance of the strategy is verified on a three-module series-connected inverter system.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Comparison of Wide-Band-Gap Technologies for Soft-Switching Losses at High
    • Pages: 12595 - 12600
      Abstract: Soft-switching power converters based on wide-band-gap (WBG) transistors offer superior efficiency and power density advantages. However, at high frequencies, loss behavior varies significantly between different WBG technologies. This includes losses related to conduction and dynamic on-state resistance (${R}_{text{DS(ON)}}$) degradation, also charging/discharging of input capacitance (${C}_{text{ISS}}$) and output capacitance (${C}_{text{OSS}}$). As datasheets lack such important information, we present measurement techniques and evaluation methods for soft-switching losses in WBG transistors which enable a detailed loss-breakdown analysis. We estimate the gate loss under soft-switching conditions using a simple small-signal measurement. Next, we use Sawyer–Tower and nonlinear resonance (NR) methods to measure large-signal ${C}_{text{OSS}}$ energy losses up to 40 MHz. Finally, we investigate the dependence of dynamic ${R}_{text{DS(ON)}}$ degradation on off-state voltage using pulsed-IV measurements. We demonstrate an insightful comparison of soft-switching losses for various normally off gallium nitride (GaN) and silicon carbide (SiC) devices. A p-GaN-gated device exhibits the most severe ${R}_{text{DS(ON)}}$ degradation and the lowest gate loss. Cascode arrangement increases threshold voltage for GaN devices and reduces gate losses in SiC transistors; however, it leads to higher ${C}_{text{OSS}}$ losses. The study facilitates the evaluation of system losses and selection of efficient WBG devices based on the trade-offs between various sources of losses at high frequencies.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Resilient Operation of Heterogeneous Sources in Cooperative DC Microgrids
    • Pages: 12601 - 12605
      Abstract: As distributed control layer makes dc microgrids vulnerable toward cyber attacks, the identification and mitigation of attacked agent(s) becomes even more challenging with heterogeneity between each source based on factors, such as capacity, reliability, and generation cost. This letter proposes a novel resilient methodology, which involves detection using adaptive discord element and immediate mitigation via an event-driven approach. The proposed approach successfully mitigates cyber attacks under experimental conditions.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • A Reconstructed S-LCC Topology With Dual-Type Outputs for Inductive Power
           Transfer Systems
    • Pages: 12606 - 12611
      Abstract: In inductive power transfer (IPT) applications, load-independent output has become more popular. This letter proposes a reconstructed S-LCC topology with dual-type outputs, which can realize constant current (CC) output and constant voltage (CV) output simultaneously. The proposed reconstructed S-LCC topology uses the same number of passive components, inductor or capacitor, as conventional S-LCC topology while provides dual-type outputs, which results in reduced cost and size. Such dual-type outputs could be treated as two independent output ports without using any decoupling methods, which can simplify the parameter design significantly. The circuit model of the proposed reconstructed S-LCC topology is analyzed in detail. Comparison between the proposed reconstructed S-LCC topology and multicoil structure is performed. Experimental prototypes with 300V/1.5 kW CV output and 10A/1 kW CC output are fabricated to verify the feasibility of the proposed topology.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Fast Simulation of Litz Wire Using Multilevel PEEC Method
    • Pages: 12612 - 12616
      Abstract: Litz wire has been an essential component for the power electronic design to reduce the eddy loss. However, there is a lack of efficient numerical algorithms to simulate Litz wires due to their complex structures. This letter proposes a multilevel partial element equivalent circuit method that significantly improves the efficiency of the simulation of the Litz wire. This method boosts the simulation efficiency at both packing level and twisting level. In the packing level, a novel meshing method is proposed to capture the skin and the proximity effect accurately and efficiently. In the twisting level, the calculation is further divided into wire level and multipole level, where filament approximation and fast multipole method are unitized, respectively. Taking advantage of symmetry and memory replication, the proposed method is significantly faster and more economical than reported electromagnetic algorithms. The efficiency and accuracy of the proposed method are validated through comparison with popular toolkits and the measurement of two Litz wires with dozens and hundreds of wire strands, respectively.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Harmonic Reduction for 12-Pulse Rectifier Using Two Auxiliary Single-Phase
           Full-Wave Rectifiers
    • Pages: 12617 - 12622
      Abstract: A simple and robust harmonics reduction scheme for 12-pulse diode rectifier using two auxiliary single-phase full-wave rectifiers (ASFRs) is proposed in this letter. The two ASFRs are installed at the dc side of the rectifier. One ASFR is connected in series with the load to directly modulate the output current of double star rectifiers (DSRs), whereas another ASFR is connected in parallel with the load to indirectly shape the output current of DSRs. The coadjutant modulation of the two ASFRs increases the output current states of DSRs first, thereby increasing the number of steps in the input line currents. This modification extends the conventional 12-step input line current to a 36-step input line current. The proposed rectifier draws near sinusoidal input line currents with the absence of 11th, 13th, 23rd, and 25th harmonics. Since only two ASFRs are sufficient, the proposed rectifier is completely passive and has the least number of component count, making it robust and simple to implement. Analytical results are experimentally verified on 1.8-kW experimental rectifiers.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • A SiC MOSFET and Si IGBT Hybrid Modular Multilevel Converter With
           Specialized Modulation Scheme
    • Pages: 12623 - 12628
      Abstract: The utilization of silicon carbide (SiC) MOSFET instead of silicon (Si) IGBT can significantly improve the performance of many converters. However, a modular multilevel converter (MMC) completely based on the SiC MOSFET suffers from high cost and high conduction loss at the high power levels. To solve these issues, a SiC MOSFET and an Si IGBT hybrid MMC are proposed in this letter. In the new topology, only one full-bridge submodule (SM) of each arm uses SiC MOSFETs, while the other half-bridge SMs use Si IGBTs. Meanwhile, a specialized modulation scheme is proposed to move most of the switching actions from the Si SMs to the SiC SM. As a result, the advantages of SiC MOSFET and Si IGBT are both utilized, and the total loss and cost of the MMC are reduced. Finally, the experimental result proves the feasibility of the topology and modulation scheme, and the further loss analysis verifies the superiority of the hybrid MMC over others.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • A Simple Equation for the Energy Stored by Voltage-Dependent Capacitances
    • Pages: 12629 - 12632
      Abstract: The parasitic capacitances of semiconductor power devices that contribute to the switching losses are voltage dependent, which can make calculations of their stored energy difficult. Typically, manufacturers will provide effective capacitance values to aid in circuit design and component selection. However, stored energy calculations using these effective capacitor values are erroneous. In this letter, we derive a new equation for the stored energy in the voltage-dependent capacitance associated with a semiconductor depletion region, such as in diodes and transistors. In particular, we show that the ½ term in ½ CV2 should be replaced by a new term γ, which depends on the device structure. By applying our proposed method to several commercial diodes and transistors, we show that it matches the measured data much better than using the effective capacitances. The proposed equation will enable better power circuit design by improving the accuracy of stored energy calculations.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • DC-DC Converter Synthesis: An Inverse Problem
    • Pages: 12633 - 12638
      Abstract: The inverse problem for the dc–dc converters refers to synthesizing converter topologies from a specified voltage gain expression. Though the flux balance principle is widely used in the analysis of dc–dc converters, its application as a synthesis tool has not been explored. This letter describes a mathematical approach to synthesize converter topologies from a required voltage gain expression by utilizing the principle of inductor flux balance. At first, the general form of gain expression for second-order converters is derived. From the general form of gain expression, the inverse problem is formulated by identifying the governing equations. The mathematical formulation of the inverse problem and highlighting challenges involved in solving it are the primary subjects of this article. To outline these challenges, a probable solution strategy of this inverse problem is presented. In order to derive a converter topology, at first, the appropriate flux balance equations are determined, and then the circuit topology is derived to establish the required flux balance. In contrast to the forward problem, the solution to the inverse problem is neither direct nor unique. Hence, getting the optimum closed-form solution to this inverse problem is an open-ended challenge with many possible approaches.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • A Quasi-Three-Level PWM Scheme to Combat Motor Overvoltage in SiC-Based
           Single-Phase Drives
    • Pages: 12639 - 12645
      Abstract: The emergence of fast switching wide-bandgap (WBG) power devices offers clear potential to implement higher power density and more efficient motor drives. However, the high voltage slew rate $(dv/dt)$ of switching transients brought significant challenges that can hamper the wide adoption of WBG devices in motor drive applications. Specifically, the aggravated motor overvoltage oscillation, due to reflected voltage phenomenon under high $dv/dt$, is one of the most considerable challenges that degrade the motor lifetime. With filter networks acting as the mainstream mitigation method, the advantages of WBG-based motor drives are compromised due to additional size and power loss of the filters. This letter proposes a novel quasi-three-level pulsewidth modulation scheme as a software solution to eliminate motor overvoltage oscillations in cable-fed drives. The proposed scheme adopts a brief zero-voltage state, with a predetermined time, in the midway of each pole-to-pole voltage transition. This allows the voltage reflections along the cable to significantly discontinue after two propagation cycles, securing the motor operation at prescribed voltage levels. The proposed scheme is applicable to two-level voltage-source inverters (VSIs). In this letter, the scheme is presented on a single-phase two-level VSI motor drive, supported with theoretical and experimental proof of concept.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Reducing Migration of Sintered Ag for Power Devices Operating at High
    • Pages: 12646 - 12650
      Abstract: Wide-bandgap power devices are usually operated at a higher temperature or larger electrical bias and the harsh conditions often lead to early failure of the widely used Ag-based die-attach materials due to electrochemical migration (ECM). Common methods to mitigate ECM tend to be quite costly and can only enhance the performance slightly under high-temperature conditions. In this letter, novel nano-Ag-based die-attach materials are designed and prepared by doping with 0.1 wt% Si nanoparticles. The higher affinity of Si to oxygen reduces oxidation of silver and increases the median time to failure at 400 °C by 4.8 times. According to the life prediction model, the materials extend the lifetime for operation at 200 °C from 9.5 to 63 years, while the cost remains unchanged. The sintered nano-Ag-0.1%Si die attachment has long-term reliability rendering them desirable for power devices operating at a high temperature.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Inter Harmonic THD Amplification of Voltage Source Converter: Concept and
           Case Study
    • Pages: 12651 - 12656
      Abstract: In this letter, with the consideration of both PLL and the inter-harmonic voltage perturbation, a technical concept of “inter-harmonic total harmonic distortion (THD) amplification” has been presented, by which a hidden output feature of voltage source converter (VSC) has been unveiled. The phenomenon has been explained in theory that the THD of current is greater than the THD of voltage under the inter-harmonic perturbation during the particular frequency range. The detailed frequency range and boundary characteristics have been given for reference. Both the theoretical analysis and experimental results based on RT-LAB validate the proposed inter-harmonic THD amplification phenomenon. This letter could deepen the understanding of the fundamental THD theory, and provide a new way to evaluate the grid integration performance of VSCs.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Modulation of Bidirectional AC/DC Converters Based on Half-Bridge
           Direct-Matrix Structure
    • Pages: 12657 - 12662
      Abstract: This letter proposes a half-bridge bidirectional isolated matrix-based ac/dc converter for compact ac/dc power conversion applications. The converter can control not only the dc voltage or current, but also the power factor of the ac current with a single conversion stage, which helps to achieve a higher power density with a lower complexity. The converter operates with zero-voltage switching or zero-current switching in all switches. Hence, the switching frequency of the converter can be increased higher, leading to smaller passive components. Besides the simple circuit, the modulation scheme derived from time domain analyses is also easy to implement. The proposed topology has been verified by experimental results for a 2-kW SiC-based prototype. A high efficiency of 96.8% was achieved at a full load condition. The current total harmonic distortion (THD) is lower than 4% and the power density is 1.8 kW/dm3.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • A Unified Power Control Method for Standalone and Grid-Connected DFIG-DC
    • Pages: 12663 - 12667
      Abstract: This letter proposes a unified power control method for the doubly fed induction generator dc (DFIG-DC) system, which can seamlessly transfer from the grid-connected mode to the standalone mode without changing a control strategy and vice versa. There is no need to detect the interconnection switch to identify whether it is grid connected or standalone. The dc voltage and stator active power are both positive correlations with the magnitude of a rotor current vector, which indicates that these two objectives can be combined as the unified power to generate the rotor current reference. The stator frequency can be controlled by the rotating speed of the rotor current vector without calculating the stator frequency, which can reduce the parameter dependence. Finally, the experiments based on a 1-kW DFIG-DC setup are carried out to verify the proposed unified power control method.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • A Novel Converter-Breaker Integrated Voltage Source Converter Based on
           High-Surge IGCT and Fault Self-Clearing Strategy for DC Grid
    • Pages: 12668 - 12672
      Abstract: Existing multiterminal voltage source converter based high voltage dc projects are constructed by separate modular multilevel converter (MMC) and dc breaker (DCB) utilizing insulated gate bipolar transistors. However, the MMC requires high-surge thyristors and the DCB should be equipped with very large turn-off solid-state switch against fault. Their independent operations are complex and unreliable by two separate control systems. In this letter, a novel converter-breaker integrated voltage source converter (IVSC) based on high-surge integrated gate commutated thyristor is proposed, and to integrate the converter and breaker operation, the fault self-clearing strategy is developed. IVSC can get rid of thyristors and replace DCB with small turn-off capability load switch. This converter-breaker integration can result in advantages including lower manufacturing cost and volume.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Virtual-Flux-Based Passivation of Current Control for Grid-Connected VSCs
    • Pages: 12673 - 12677
      Abstract: This letter proposes a passivity-based current control (CC) scheme for voltage-source converters, featuring a virtual-flux-based damper and a passive output admittance with a wide range of time delay involved in the CC loop. The admittance modeling and experimental tests validate the effectiveness of the approach.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Isolated Ultrafast Gate Driver with Variable Duty Cycle for Pulse and VHF
           Power Electronics
    • Pages: 12678 - 12685
      Abstract: Ultrafast and isolated gate drivers advance the development of pulse and very high frequency power electronics for applications that include LiDAR, space systems, miniaturized hardware, and testing of emerging ultrafast devices. The isolated ultrafast gate driver in this letter achieves a gate voltage slew rate above 12 GV/s with rise and fall times below 260 ps with the proper choice of components. Magnetic isolation provides transient immunity and positive feedback enables dynamic dc restoration to allow arbitrarily long on- and off-times and preserve variable duty cycles. With the isolated ultrafast gate driver, an EPC 2038 GaN FET achieves a drain voltage slew rate of over 37 GV/s when hard-switching and improves total efficiency by 8% (including gating loss) with a careful choice of logic inverters in a symmetric 100 MHz current-mode class D (CMCD) wireless power transfer system. The ultrafast gate driver with isolation and positive feedback was implemented with a commercial radio frequency signal transformer and discrete logic inverters and validated in a hard-switching double pulse test, a narrow pulse test repeating at 165 MHz, and a 100 MHz soft-switching CMCD resonant converter.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Analysis and Design of the LLC LED Driver Based on State-Space
           Representation Direct Time-Domain Solution
    • Pages: 12686 - 12701
      Abstract: The LLC resonant converter has been widely used in switched power supply covering several kinds of applications. Although it has been the focus of numerous analysis, their general time-domain (TD) solution is not completely enclosed due to its complexity given by the multiple resonance nature and its variable structure behavior. Consequently, the LLC converter design is also impaired by the lack of an enclosed TD solution. To overcome these issues, this article systematically presents a highly accurate TD solution of the LLC converter supplying a light-emitting diode (LED) load, which is obtained from the state-space representation direct TD solution. Dissimilar to preceding analyses, all the converter states are considered and no current and voltage sinusoidal or average value approximations are taken. Finally, supported by the TD analysis, a new LLC LED driver design procedure is introduced, which is oriented by weighted-average-efficiency concept and constraints that ensure zero voltage switching, enough power gain, and practical switching frequency range over a wide operating window. Experimental results show the feasibility of the proposed design procedure as well as the accurate TD behavior prediction of the LLC converter supplying an LED load. This article is accompanied by active content that exemplifies the proposed TD solution and design procedure.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • A Fault-Tolerant Hybrid Cascaded H-Bridge Multilevel Inverter
    • Pages: 12702 - 12715
      Abstract: The cascaded H-bridge (CHB) inverter is one of the most attractive multilevel topologies for renewable energy applications. Due to the fact that CHB inverters employ a large number of components, they suffer from a higher probability of fault, which reduces the system reliability. A fault-tolerant operation for a CHB inverter is described in this article. New features ensure reliable and robust operation of the converter in the event of a fault. The proposed strategy uses an additional cross-coupled CHB (X-CHB) unit in companion with the existing CHB units to support the output voltage and ensure continuity of operation in the event of an open/short-circuit fault. The operation of the proposed X-CHB inverter is described in detail. Simulation and experimental verification of the proposed concept are demonstrated using a seven-level CHB. Both simulation and experimental results confirm the fault-tolerant operation of the X-CHB for a battery energy storage system in case of switch faults.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • An Integrated Boost Active Bridge Based Secondary Inductive Power Transfer
    • Pages: 12716 - 12727
      Abstract: Due to its inherent safety, robustness, and high efficiency, inductive power transfer (IPT) technology is highly suitable for the implementation of wireless electric vehicle (EV) chargers. In addition, IPT-based EV chargers can provide consistent vehicle-to-grid services, opportunistic charging, and in-motion/dynamic charging. However, designing such systems to adhere to applicable standards, while ensuring constant power transfer, and high efficiency, remains a challenge. For example, to meet the requirements outlined by SAE J2954, a wireless charger should tolerate a coupling change from 10% to 30% and a battery voltage variation from 280 to 420 V. A boost active bridge (BAB) converter presented in previous work was shown as a suitable solution; however, this system utilized two additional dc inductors. As such, this article presents a BAB converter, which integrates the current splitting functionality previously achieved using two dc inductors into a Double D magnetic coupler. This achieves a reduction in the magnetic volume of approximately 70%. Analysis of the proposed converter together with detailed design guidelines to maximize power transfer efficiency for a system designed to meet the SAEJ2954 specifications is also presented. Experimentally obtained efficiencies from a 7-kW prototype system showed minimal variation over the full range of loading conditions, ranging between 94.2% and 92%.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Affine Nonlinear Control of a Multivariate Inductive Power Transfer System
           With Exact Linearization
    • Pages: 12728 - 12740
      Abstract: In this article, an exact linearization algorithm and nonlinear control scheme of the inductive power transfer (IPT) system for electric vehicles (EVs) are proposed, considering a variation in system operating point. For ease of modeling, the secondary side of IPT system is equivalent to a reflected reactor and resistor on primary side at different operating frequencies. By utilizing the exact linearization method, the nonlinear model is accurately transformed into a linear one at whole operating points. Besides, to acquire constant current$backslash$voltage (CV/CC) charging and zero voltage switching (ZVS) operating for EVs, the controllers are designed and optimized in the linear space, and then inverse mapped to the nonlinear space. This avoids designing different controllers for each operating point. Compared with a traditional PI controller, the nonlinear control scheme suggested in this article enables the system to obtain a fixed dynamic response even if the operating point of the IPT system changes. Finally, practical results obtained from a hardware prototype are included. They confirm the performances of the system and indicate that the proposed nonlinear control scheme can automatically maintain CC$backslash$CV output and ZVS operation with a constant response time of 10 ms.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • On Beat Frequency Oscillation of Two-Stage Wireless Power Receivers
    • Pages: 12741 - 12751
      Abstract: Two-stage wireless power receivers, which typically include an ac–dc diode rectifier and a dc–dc regulator, are popular solutions in low-power wireless power transfer applications. However, the interaction between the rectifier and the regulator may introduce beat frequency oscillation on both the dc-link and output capacitors. In this article, the cause of the beat frequency oscillation and its related issues are investigated with the corresponding design solution on alleviating the oscillation discussed. Theoretical and experimental results verifying the presence of beat frequency oscillation in the two-stage wireless receiver system are provided. Our study shows that the beat frequency oscillation can be significantly alleviated if appropriate design solutions are applied.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Dynamic Improvement of Inductive Power Transfer Systems With Maximum
           Energy Efficiency Tracking Using Model Predictive Control: Analysis and
           Experimental Verification
    • Pages: 12752 - 12764
      Abstract: For inductive power transfer (IPT) systems, loads and system input voltages are subject to change, which affects system efficiency and stability. This article presents a perturbation and observation (P&O) method for maximum energy efficiency tracking (MEET) with a model predictive control (MPC) scheme for improving the dynamic performance of series–series compensated IPT systems. In the IPT system, the inverter at the primary side incorporates the P&O method and phase shift modulation (PSM) to minimize system input power. Meanwhile, the rectifier at the secondary side is controlled by MPC control based PSM to improve the dynamic response of the output voltage. Simulated and experimental results show that, compared to the PI controller, the MPC controller, based on a simple but accurate mathematical model, has a better dynamic response to load and input voltage variations. With the MPC controller, the settling time of the output voltage is reduced by 85.7%, which indicates a particularly stable power supply to the load. Furthermore, MEET adopting the P&O method in the IPT system can promote the system efficiency by 1.85% on average when the output voltage is regulated by the MPC controller.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Optimal Transmission Range and Charging Time for Qi-Compliant Systems
    • Pages: 12765 - 12772
      Abstract: Although widespread in the market, the wireless power transfer devices following the Qi Standard suffer from limited transmission range and link instability. Previous works often address these issues by proposing improvements for both transmitting and receiving sides, which disposes of the Qi interoperability and ease of purchasing. This article proposes an optimal transmitting-range-maximization algorithm for the receiving part of a Qi-compliant system. The algorithm actuates over the receiving circuit by dynamically adjusting its internal impedance. The proposed method obtains the optimal result in $Theta (1)$ time and does not require any direct information from the transmitting part neither any preparameterized data. Simulation results indicate that the proposed algorithm can mitigate the issue of re-establishing the link when the coils are loosely coupled.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Design of PWM-SMC Controller Using Linearized Model for Grid-Connected
           Inverter With LCL Filter
    • Pages: 12773 - 12786
      Abstract: Nowadays, various sliding-mode control (SMC) methods have been successfully applied to the digitally controlled grid-connected inverter (GCI) with an LCL filter. However, how to design the pulsewidth modulation based SMC (PWM-SMC) controller needs to be further explored, especially upon the large variation of the parameters drift and the delay issue. In this article, the essence of two classic SMC methods used in the power converter area is first analyzed in detail. Thus, a novel design of the PWM-SMC controller using a linearized model for the three-phase GCI with an LCL filter is proposed. Based on this, a three-loop step-by-step design of the PWM-SMC controller is developed, by using the closed-loop pole locations. A robust analysis against the parameters drift is also studied. In addition, a discrete state observer is adopted to reduce the number of sensors. Furthermore, a discussion between the proposed control strategy with the existing SMC methods and the full-state feedback controller is carried out. Finally, a 3-kW lab device designed on the dSPACE is constructed to verify the feasibility of the proposed strategy and the correctness of the theoretical analysis.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • The Modular Multilevel DC Converter With Inherent Minimization of Arm
           Current Stresses
    • Pages: 12787 - 12800
      Abstract: The modular multilevel dc converter (M2dc) is a partial power processing dc–dc converter that is gaining popularity for medium-voltage and high-voltage dc (HVdc) grid applications. However, internal ac current stresses go up as the step-down dc voltage ratio increases, leading to increased cost and losses, and ultimately renders the M2dc impractical for some applications. The HVdc autotransformer (AT) (HVdc-AT) is another class of the partial power processing dc–dc converter that circumvents this issue by using a transformer for interarm ac voltage matching, although the core must tolerate a very large dc voltage stress between windings that leads to increased magnetics size and weight. Interestingly, the M2dc does not suffer from interwinding dc voltage stresses. This article presents a new class of the partial power processing dc–dc converter that uses an integrated center-tapped transformer to merge the best traits of the M2dc and HVdc-AT. Comparative analysis reveals the proposed converter can minimize ac current stresses at all operating points while also achieving a significant reduction in transformer area product relative to the HVdc-AT. A dynamic controller is proposed that regulates dc power transfer while ensuring balanced capacitor voltages. The converter operation and dynamic controls are validated by simulation and experiment.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • DC Voltage Ripple Optimization of a Single-Stage Solid-State Transformer
           Based on the Modular Multilevel Matrix Converter
    • Pages: 12801 - 12815
      Abstract: The modular multilevel matrix converter (M3C) is introduced and applied to a single-stage ac/dc solid-state transformer (SST), which uses only one concentrated medium-frequency transformer (MFT) for isolation. As a result, the transformer insulation design is simplified significantly and higher power density could be achieved. Meanwhile, a novel decoupling transformation based on two internal three-phase circulating systems is proposed to improve the previous method. Through this transformation, the unbalanced capacitor voltage components can be divided into four independent dimensions, which correspond to four kinds of capacitor voltage ripple frequency. And a dc-side vector model is then established to calculate the required circulating current reference for capacitor balancing. Besides, under the application of SST, the capacitor voltage ripple suppression strategy via injection of extra circulating current is proposed. The amplitude and frequency index is optimized to obtain the best effect. Therefore, the submodule capacitor volume can be reduced to achieve higher power density. Simulation and experimental results are also provided to verify the theoretical analysis.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Interleaved Multilevel Boost Converter With Minimal Voltage Multiplier
           Components for High-Voltage Step-Up Applications
    • Pages: 12816 - 12833
      Abstract: In this article, a new interleaved multilevel boost converter (interleaved-MBC) is suggested with minimal voltage multiplier (VM) cells for high-voltage step-up applications. The interleaved-MBC is derived in such a way that the maximum utilization of the VM circuit operation can be achieved by the interleaved structure. Furthermore, compared to existing multilevel interleaved converters, the reduced number of capacitors and diode with equal voltage rating makes it more attractive. Similar to the existing multilevel converter, the feature of the interleaved-MBC provides the extension of the number of levels to achieve the necessary voltages just by adding similar capacitor–diode stages (single capacitor and single diode are required to increase the stage by one). The features like continuous input current, low-input ripples, high voltage conversion ratio, and reduced stress on devices make the proposed converter more suitable for the voltage step-up applications, such as dc link, hybrid distribution systems, hybrid photovoltaic systems, etc. The detailed analysis of the converter is carried out by considering the nonidealities in the power circuit. The operation of the interleaved-MBC is presented for continuous and discontinuous conduction modes with boundary conditions. The components selection criterion and the comparison of converters are presented with suitable discussions. The converter is experimentally tested, and the obtained results validate its performance and functionality.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Synchronization for an MMC Distributed Control System Considering
           Disturbances Introduced by Submodule Asynchrony
    • Pages: 12834 - 12845
      Abstract: The modular multilevel converter (MMC) is a promising topology for HVdc applications, which typically adopts a distributed control architecture to manage considerable submodules (SMs) in the system. SM synchronization is necessary for an MMC distributed control system to cope with the local controller clock discrepancy and asynchrony due to the manufacturing tolerance. This article proposes a synchronization scheme for the MMC distributed control system taking the disturbances introduced by the SM asynchrony into account. The MMC models considering SM asynchrony reveal that the asynchrony introduces harmonics around the carrier frequency in MMC output and the circulating current. The interaction between the SM switching harmonics and arm current harmonics leads to divergence of the capacitor voltages. The MMC distributed control system cannot entirely restrain the voltage divergence and maintain the system stability owing to the control capability saturation of the balancing controller. According to the theoretical analysis, the synchronization interval is properly selected considering the harmonic contents in the MMC output, the capacitor voltage deviation, and the distributed control system stability. The theoretical models and the proposed synchronization scheme are validated experimentally on an MMC prototype.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Reconfigurable Hybrid Energy Storage System for an Electric Vehicle
           DC–AC Inverter
    • Pages: 12846 - 12860
      Abstract: Hybrid energy storage systems using battery packs and super capacitor (SC) banks are gaining considerable attraction in electric vehicle (EV) applications. In this article, a new modular reconfigurable multisource inverter (MSI) is proposed for active control of energy storage systems in EV applications. Unlike the conventional approaches, which use massive high-power dc–dc converters with bulk magnetic elements for combining SC banks and battery packs, the new approach utilizing the MSI offers magnetic-less structures. This reduces the weight and volume of the power electronics interface and offers simple control. Along with the proposed MSI, a space vector modulation technique and a deterministic state of charge (SOC) controller are also introduced for the control of the switching actions and operation of the SC bank. Simulations using MATLAB/Simulink and experimental results on a scaled down lab prototype are studied to assess the concepts.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • A Novel High-Frequency Bipolar Pulsed Power Generator for Biological
    • Pages: 12861 - 12870
      Abstract: High-frequency bipolar high-voltage pulsed electric field can be used in tumor ablation to uniform the electric field distribution in the ablated region and inhibit muscle contraction effectively. Developing a high-frequency bipolar pulsed power generator (HBPPG) with wide range of specifications, such as voltage magnitude, waveform, repetition rate, and pulsewidth, is of great significance for promoting the clinical application of irreversible electroporation. Hence, in this article, a novel modular high-voltage HBPPG circuit topology is proposed for such application. Each module consists of an H-bridge and an isolated inductor. Theoretical analysis, simulation, and experimental results show that this generator perfectly combines the advantages of solid-state Marx and bridge circuit, with high stability and redundancy. The pulse frequency, pulse duration, and waveform can be flexibly adjusted by a controller software algorithm according to load parameters. The viability of the proposed HBPPG is demonstrated by PSpice simulation and equal-scale prototype. The key parameters of the developed HBPPG are as follows: voltage amplitude up to ±10 kV with 500 ns–5 μs pulsewidths, 500 kHz within the burst, and 10 kHz within the continuation limited by the input high-voltage dc power supply. All the pulse parameters can be programmed arbitrarily.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • A Novel ZVS High-Step-Up Converter With Built-In Transformer Voltage
           Multiplier Cell
    • Pages: 12871 - 12886
      Abstract: This article proposes a novel interleaved high-step-up dc–dc converter with zero voltage switching (ZVS). Through a built-in transformer voltage multiplier cell (VMC) the high voltage conversion ratio is achieved without the narrow duty. By applying active clamp scheme, all of the power MOSFETs are switched with ZVS which minimizes the switching losses of the proposed converter. Besides the voltage stress across the switches is decreased and can be controlled by the built-in transformer turns ratio enabling utilization of low on-state resistance and low forward voltage drop semiconductors. Due to the interleaved structure, the input current ripple is minimized and the thermal stress is shared between the phases. Meanwhile, the charge balance of the capacitors give rise to equal current sharing performance for the two input inductors. All of these factors reduce the power losses and improves the performance of the proposed converter. Finally, in order to verify the operation of the proposed converter, a 35-V input voltage to 500-V output voltage prototype with the rated power of 1 kW is fabricated and tested in the laboratory.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Design and Assessment of External Insulation for Critical Components in a
           Medium Voltage SiC-Based Converter via Optical Method
    • Pages: 12887 - 12897
      Abstract: Exposed metal or insulator to air interfaces widely exists in medium voltage SiC-based converters. To effectively address external insulation along such interfaces, a large insulation distance in the air is applied. However, such insulation tends to significantly impair converter power densities and performances. Targeting the external discharge free design approaches that reflect the relationship between insulation structures and square wave excitation parameters is highly demanded. Moreover, due to possible fabrication issues and insulation degradation, massive external discharges may still occur, even that they should be eliminated by the design. Therefore, insulation assessment for the entire system, or at least for critical components, is necessary. In this article, silicon photomultiplier (SiPM)-based external discharge detection solutions are introduced. Then, for a self-designed SiC-based medium voltage converter, the SiPM sensors enable both its external insulation design and assessment. By using SiPM sensors, two types of external discharges are characterized under square wave excitation, and thus, general design suggestions are developed. Moreover, as shown by two examples, SiPM sensors can be used to assess the external insulation for converter applications. Based on the experimental data, analysis, and real examples, the results of this study can be used to design and assess the external insulation for future medium voltage, high-power density SiC-based converters.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Comprehensive Spectral Analysis of PWM Waveforms With Compensated DC-Link
    • Pages: 12898 - 12908
      Abstract: In the available literature, including reference books on the topic, the spectral analysis of voltage waveforms obtained through the use of pulse width modulation (PWM) relies on the assumption of an ideally flat voltage across the dc-link of a considered switching structure. Nevertheless, certain converter families (e.g., modular multilevel converter, characterized by the presence of distributed and floating dc-links), feature low-frequency oscillations of dc voltage within their switching stages. On these terms, the flat dc-link assumption cannot be considered valid from both theoretical and practical viewpoints. In case carrier-based modulation is employed, unless properly compensated through the modulation signal adjustments, the above mentioned voltage oscillations cause undesirable distortion of the converter currents. However, the very same adjustments of modulation signals introduce additional challenges in the spectral analysis of the voltage across the ac terminals of an observed switching stage. This article provides the ac terminals voltage analysis of a single half-bridge experiencing dc-link oscillations, which are compensated through the modulation signal generation process. PWM with the conventional triangular carrier is considered, while all the results are presented in a generalized form, making them easily extendable to cascaded structures. All of the presented results were experimentally validated.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Hybrid Alternate-Common Arm Converter With High Power Capability:
           Potential and Limitations
    • Pages: 12909 - 12928
      Abstract: This article studies a new hybrid converter that utilizes thyristors and full-bridge (FB) arms for achieving high-power capability with reduced semiconductor power rating compared to the FB modular multilevel converter. The study covers the theoretical analysis of the energy balancing, the dimensioning principles, the maximum power capability, and the limitations imposed by the discontinuous operation of the converter. Based on the analysis of these aspects, the theoretical analysis is concluded by identifying the operational constraints that need to be fulfilled for maximizing the power capability of the converter. It is concluded that the maximum power capability can be achieved for a certain range of modulation indices and is limited by both the commutation time of the thyristors and the power angle. Moreover, the P–Q capability of the hybrid converter is presented and discussed. Finally, simulation and experimental results that confirm the theoretical analysis and the feasibility of the studied converter are presented and discussed.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • A Complete HSS-Based Impedance Model of MMC Considering Grid Impedance
    • Pages: 12929 - 12948
      Abstract: Harmonic state space (HSS) is seen as an effective impedance modeling method to precisely characterize the internal harmonic features of the modular multilevel converter (MMC). However, the existing MMC impedance models assume the ideal grid, ignoring the grid impedance, and they also do not incorporate the widely used dual-loop control and phase-locked loop (PLL). In this article, a complete MMC impedance model based on HSS is proposed to reveal the grid impedance coupling effect of MMC. The model analysis results demonstrate that the MMC impedance is coupled with the grid impedance due to the internal harmonics. This coupling causes MMC to be affected by the grid impedance and may cause instability. On the other hand, the proposed model not only consists of the ac current and the circulating current control, but also incorporates dc voltage outer loop and PLL with a clear physical meaning. Based on the proposed model, this article illustrates the factors that will enhance the coupling, which shows that the proposed model has to be used to improve the accuracy of the analysis. Finally, effectiveness of the proposed model is verified by simulation and experimental results.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Zero-Voltage and Zero-Current Switching Dual-Transformer-Based Full-Bridge
           Converter With Current Doubler Rectifier
    • Pages: 12949 - 12958
      Abstract: A novel dual-transformer-based full-bridge (DT-FB) converter with a current doubler rectifier (CDR), which can solve the drawbacks of existing FB converters, is proposed in this article. In the primary side of the proposed converter, two switching legs, two transformers, and two blocking capacitors form two half-bridge inverters. The secondary side composes of two output filter inductors and four power diodes, which connect with the form of the CDR. By employing this structure, a wide range of zero-voltage switching for leading-leg and zero-current switching for lagging-leg can be achieved. In the proposed converter, the output power is shared by two small-sized transformers and inductors instead of large-sized ones, which contributes to the improvement of power density and efficiency. Compared with the traditional FB converter, the proposed converter can obtain higher voltage gain, better rectified voltage, and lower current ripple. The operation principle, theoretical analysis, and design considerations of the proposed converter are described in this article. A prototype with 300–380 V input and 100 V/ 10 A output is designed and tested to confirm the effectiveness of the proposed converter.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Analysis, Design, and Implementation of Impulse-Injection-Based Online
           Grid Impedance Identification With Grid-Tied Converters
    • Pages: 12959 - 12976
      Abstract: Grid impedance information occupies a fundamental and crucial position for the operation of grid-tied converters. Consequently, accurate and fast extraction of grid impedance is vital. The impulse injection method applied under the control loop of a grid-tied converter, which is commonly used to extract linear grid impedance online, is relatively reasonable in terms of device cost, measurement speed, simplicity, and design flexibility. However, the selection of impulse and design of impulse parameters mostly depend on rules of thumb, without theoretical guidance, leading to insufficient measurement accuracy in target frequency section and greatly burdening the system. To address these issues, a systematic guidance is proposed for analysis, design, and implementation of impulse-injection-based grid impedance identification. By comparing the spectra of several basic impulses with unipolar and bipolar forms and analyzing the impact when impulse parameters are altered, a guidance for impulse selection for different measurement scenarios is presented. Based on this guidance, an asymmetric bipolar sawtooth wave with a defined asymmetry ratio of $boldsymbol{rho } = 0.5$ is chosen in this article for broadband measurement of grid impedance. Furthermore, a related parameter design procedure with optimal injection position and instant is also proposed to reduce system burden and eliminate overmodulation when injecting the impulse. Finally, theoretical results are validated by experiments.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Modulation and Control of Series/Parallel Module for Ripple-Current
           Reduction in Star-Configured Split-Battery Applications
    • Pages: 12977 - 12987
      Abstract: Split-battery converters based on cascaded H-bridges (CHBs) are gaining popularity due to their excellent physical modularity. During operation, however, the batteries experience substantial current ripple. Conventional ripple-current reduction methods rely on bulky passive components or complicated control. This article presents modulation and common-mode voltage injection methods for cascaded double-H-bridge converters (CHB2). The control methods directly mitigate the source of the ripple current—the fluctuating arm power—by exploiting the parallel interconnection across the CHB2 arms. In the lab setup, the proposed solution approximately halves the battery current ripple compared to the CHB counterpart. Finally, this article studies component sizing and limitations of the proposed solution.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Single-Stage PV-Grid Interactive Induction Motor Drive With Improved Flux
           Estimation Technique for Water Pumping With Reduced Sensors
    • Pages: 12988 - 12999
      Abstract: This article deals with a photovoltaic-grid integrated system operating an induction motor (IM) coupled to a water pump. A simple dc-link voltage regulation approach is adopted for the power transfer. This system is utilized to primarily feed the induction motor-driven water pump and when water pumping is not desired, the power is delivered to the utility. This system requires two current sensors and two voltage sensors in total for sensing and estimation purpose. Induction motor phase currents are estimated from dc-link current by modified space vector modulation (SVM) technique. The speed estimation in this system is achieved by artificial neural network-based model reference adaptive system with a third-order integrator for flux estimation and is capable of controlling the power flow as per demand. The field-oriented control is used for speed control of an IM-pump. A third-order integrator based unit voltage generation algorithm is used to control the power transfer in both the direction between utility and the IM drive with water pump by regulating dc-link voltage. The appropriateness of the system is justified by simulated results on MATLAB/Simulink platform and test results procured with the help of a developed prototype during varying solar irradiances.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Optimization Design and Control of Single-Stage Single-Phase PV Inverters
           for MPPT Improvement
    • Pages: 13000 - 13016
      Abstract: Due to the inherent double-frequency (2f0) ripple in single-stage single-phase photovoltaic grid-connected inverters, the maximum power point tracking (MPPT) will inevitably be affected. To improve the MPPT performances, a passive LC power decoupling circuit with a robust second-order sliding-mode control (SOSMC) is thus proposed in this article. With the passive LC decoupling path, the double-frequency pulsation on the dc link is effectively cancelled out. Thus, the MPPT accuracy is significantly enhanced, and the utilization of a small dc-link capacitor becomes possible. However, resonance between the LC circuit and the main dc-link capacitor may appear, which can be damped through an active damping method. Additionally, the proposed SOSMC ensures good steady-state, dynamic performance (voltage fluctuation and settling time), and the robustness of the dc-link voltage, which is also beneficial to MPPT control in terms of high accuracy and fast dynamics. The systematic design of SOSMC is presented, and a detailed parameter optimization design of LC decoupling circuit is discussed. Experimental tests are performed on a 2.5-kW single-stage single-phase grid-connected inverter, and the results validate the effectiveness of the proposed strategy.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • A Step-Up Nonisolated Modular Multilevel DC–DC Converter With
           Self-Voltage Balancing and Soft Switching
    • Pages: 13017 - 13030
      Abstract: Evolving from the popular modular multilevel ac–dc converter, the single-stage nonisolated modular multilevel dc–dc converter (MMDC) is advantageous for medium- and high-voltage applications. However, exploiting ac circulating power to balance the submodule energy, when utilized for high step ratio applications, existing MMDC topologies suffer from circulating current through the arms and large filter inductor at the low-voltage side. To overcome these issues, this article presents a new power transfer mechanism to balance the submodule energy automatically by reconstructing the half-bridge submodule into a quasi-resonant circuit. Based on this submodule structure, a new MMDC topology for step-up applications is proposed. Compared to the existing MMDCs, the proposed one offers the following advantages. First, the common-mode circulating current through the lower and upper arms is avoided. Second, the self-balancing of the capacitor voltages is guaranteed by the proposed modulation method to insert and bypass adjacent submodules in a complementary manner. Third, the soft-switching operation is achieved for the majority of the switches to alleviate switching losses. Fourth, the voltage stress across the input side inductor is limited to the submodule voltage, thereby reducing the size of the inductor. Simulation analysis and experimental results verify the performance of the proposed MMDC.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Sequence Impedance Modeling and Stability Analysis for Load Converters
           With Inertial Support
    • Pages: 13031 - 13041
      Abstract: Load converters with inertial support are used to enhance the system inertia. However, these converters may fail to operate stably in the weak grid. In this article, sequence impedance modeling and stability comparison analysis are proposed for the load virtual synchronous machine (LVSM) and the load converter with virtual inertia control (LCVIC). First, the universal sequence impedance formulas are derived by considering dc-link voltage dynamics and frequency-coupling effects. Then, the precise sequence impedance models are built for impedance characteristics analysis of LVSM and LCVIC. The analysis shows that the positive-sequence impedance of LVSM is generally inductive in the middle-frequency band, which is basically consistent with the grid impedance. In contrast, the positive-sequence impedance of LCVIC is negative-resistive-capacitive (i.e., phase angle is between −180° and −90°) in the middle-frequency band, which may lead to harmonic oscillation in the weak grid. Furthermore, the effects of grid impedance, load power, and other control parameters on the stability are analyzed for the two load converters based on the derived model and Nyquist stability criterion. The analysis results reveal that LVSM has better stability than LCVIC in the weak grid. Finally, the experimental results validate the correctness of the theoretical analyses.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • A High Performance Interleaved Discontinuous PWM Strategy for Two
           Paralleled Three-Phase Inverter
    • Pages: 13042 - 13052
      Abstract: This article aims to obtain the optimal combination of the switching loss, maximum zero-sequence circulating current (ZSCC), and line current ripple, which benefits most of the applications. The analysis shows that the interleaved discontinues pulsewidth modulation (IDPWM) maintains the minimum switching loss and line current ripples, but it introduces a larger ZSCC. Therefore, to obtain the optimal combination of the switching loss, maximum ZSCC peak, and line current ripple, it is essential to retain the minimum switching times and the optimal line current ripple of IDPWM but further reducing its overly large ZSCC. Further analysis reveals that IDPWM includes the vector combinations with medium ZSCC change rates, resulting in the larger ZSCC. Given the redundancies of the vector combinations, this article proposes a simple matrix to modify the original modulation signals of IDPWM, eliminating the medium ZSCC change rates. The proposed PWM scheme retains the minimum line current ripple and switching times as those of IDPWM while further reducing its overly large ZSCC, as validated by analytical results as well as experimental results. Since the proposed method obtains the optimal combination among switching loss, line current ripple, and maximum ZSCC peak, we name the proposed PWM scheme a high-performance DPWM.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Wide Input Voltage DC Electronic Load Architecture With SiC MOSFETs for
           High Efficiency Energy Recycling
    • Pages: 13053 - 13067
      Abstract: A SiC three-stage converter architecture of energy recycling dc electronic load with high frequency isolation is proposed. With interleaving boost converters and a LLC-DCX using 1200-V SiC MOSFETs as high frequency isolation pre-regulation stage, the proposed architecture can adapt to wide input voltage of 150–750 V with high efficiency. As the bus voltage is 780 V, a T-type three-level inverter is accepted as grid-connected stage for low leakage current, small grid current harmonics and high conversion efficiency. The transfer mechanism of second harmonic component of the input current ripple is analyzed and is well suppressed by proposed current program control. An overshoot-free soft-start control is proposed to minimize resonant current peak using the inverter reverse operation. The switching frequency reduction modulation control is proposed to solve the extremely low duty-cycle problem under high input voltage and low load condition. A seamless mode transition digital control of three-stage load is proposed with smoothly switched capability between the input current loop and input voltage loop to solve the duty-cycle mutation problem during mode transition. A 5-kW, 300-kHz SiC prototype with 150–750 V input was built. The peak full-load efficiency of three-stage architecture is 95% at 750 V input. The power density is 12.6 W/in3.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Resonance-Based Optimized Buck LED Driver Using Unequal Turn Ratio Coupled
    • Pages: 13068 - 13076
      Abstract: Losses in light-emitting-diode (LED) driver cause increasing temperature and shorten their lifespan. Therefore, improving the efficiency of LED drivers not only saves energy but also is indispensable to increase their lifespan. In this article, a new LED driver topology is proposed to improve the performance of valley switching by decreasing the mosfet switching losses. The proposed topology is designed in a way that the mosfet works at the significantly lower switching and conduction losses in compared with conventional LED drivers. It elaborates how the proposed topology also improves the overall efficiency by decreasing power losses in other main elements of the driver, including inductance and diode. In addition, a new valley switching implementation is introduced for the new converter, which decreases the cost and dimension of the LED drivers. The experimental results confirm the high efficient operation of the proposed LED driver by reaching the efficiency up to 97% at a wide range of operating voltage.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Three-Port Full-Bridge Bidirectional Converter for Hybrid DC/DC/AC Systems
    • Pages: 13077 - 13084
      Abstract: Sustainable solutions such as renewable energies, distributed generation, energy storage, and electric vehicles require power conversion and advance control techniques. This process is usually done in two stages by more than one power converter, specially in hybrid systems, increasing power losses and costs. The configuration with two dc stages and one ac port is widely used in several applications, such as grid-connected photovoltaic inverters; fuel cells, hybrid and electric vehicles; and ac/dc microgrids. Thus, three-port topologies have been developed to operate such systems, most of them comprising multiple power processing stages for the connection of the different elements. This article proposes a three-port full-bridge converter with a single power processing stage for dc/dc/ac systems. The ac port can be single-phase or three-phase, using two legs like an H-bridge or three legs like the conventional three-phase inverter. In both configurations, each leg is used as an inverter and as a buck-boost converter at the same time. The converter is able to manage the power flow among three ports with just four or six switches through a multivariable control strategy. Simulation and experimental results show the capability of the converter to manage the interaction between a battery and a capacitor connected to the grid achieving a fast dynamic response, bidirectional capability in all ports and reduction of components.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • A QR-ZCS Boost Converter With Tapped Inductor and Active Edge-Resonant
    • Pages: 13085 - 13095
      Abstract: Boost dc/dc converters are widely used in renewable energy systems. With growing demand for high efficiency and high voltage gain, many new topologies have been published. This article proposes a novel zero current switching (ZCS) boost converter with a tapped inductor and active edge-resonant cell (AERC). To achieve high voltage gain, the tapped inductor was implemented in the structure of the converter, and by employing an AERC, ZCS of transistors was attained. Subsequently, by employing a resonant operation current, overshoots by leakage inductance were eliminated. This article presents an analysis, mathematical derivations, and laboratory test results. Finally, a 30–50 V input, 380 V output, and 750 W output power laboratory model operating with 45–100 kHz switching frequency was built and tested. The maximum reported efficiency was 96.6%. Soft switching of semiconductors was achieved in the whole output power range.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Average Inductor Current Measure and Control Strategy for Multimode
           Primary-Side Flyback Converters
    • Pages: 13096 - 13103
      Abstract: Primary-side flyback converter (PSR) is widely used among small and medium power applications for its simplicity and cost effectiveness. However, it is hard to measure the current of secondary side due to the special structure characteristic of PSR. Conventionally, a peak current measurement strategy is adopted to measure the current of primary inductor. However, the sampling method is just for one conduction mode and is affected by the propagation delay between the control signal and actual turn-off instant of mosfet. Thus, a compensation circuit is needed to improve the accuracy, which leads to a large area and cost of the controller. In this work, a kind of average inductor current measure and control strategy for multimode is introduced. The average inductor current measurement strategy is based on the Miller stage to recognize the state of the mosfet, which eliminates the error caused by the mosfet. The average current of primary inductor is obtained and there is no need to estimate the rising slope and the peak value of the inductor current. To verify the feasibility of the proposed method, a controller for charging application is fabricated integrated with the proposed method. Hardware experimental results show that the control system can properly operate in multimode. The accuracy of constant output current is ±1% and the line regulation of the system is 1.6% under the input line voltage ranges from 85 to 265 Vac.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Single-Inductor Multi-Input Multi-Output DC–DC Converter With High
           Flexibility and Simple Control
    • Pages: 13104 - 13114
      Abstract: Multi-input multi-output (MIMO) dc–dc converters can integrate multiple input sources and output loads simultaneously. This article proposes a new single-inductor MIMO dc–dc converter with a wide conversion ratio. The proposed converter allows input sources to be added or removed seamlessly with no cross-regulation problem. Meanwhile, the outputs are independently controlled, i.e., the load change at one output cell will not affect the other interconnected output cells. Constant current control is the main control requirement. When constant current control is applied to all input cells, the power provided by each input source is proportional to the voltage magnitude of the source. When the constant current control is applied to some of the input cells, the input sources with direct duty-cycle controlled input cells can provide specific power through controlling the duty cycles of the switches of the corresponding input cells. Moreover, the switching time of switches is irrelevant. Therefore, it is easy to realize the high extension capability for arbitrary inputs/outputs. A dual-input dual-output prototype is constructed to illustrate the performance of the proposed converter. The corresponding component design is presented.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • AC–AC Hybrid Boost Switched-Capacitor Converter
    • Pages: 13115 - 13125
      Abstract: In this article, a hybrid boost switched-capacitor converter operating as an ac–ac solid-state autotransformer is presented. The topology integrates a basic inductive switching cell and a switched-capacitor ladder cell, performing a direct energy conversion with a high-gain output voltage. The theoretical analysis presents the main operational characteristics of the hybrid converter, including the voltage stresses across the devices, the equivalent average electric circuit model, and the calculation of current stresses considering the partial charging of the capacitors. A design methodology is described, focusing on the modulation technique and criteria for determining capacitors, semiconductor devices, inductor, and switching frequency. Validation was carried out based on simulation and experimental results obtained with a single-phase prototype with 55/220-V voltage conversion and 1-kVA rated power at 60 Hz. Additional tests verified the operation at different grid frequencies, loads (inductive and nonlinear), and with 14 different input–output connections.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Hold-Up Time Compensation Circuit of Half-Bridge LLC Resonant Converter
           for High Light-Load Efficiency
    • Pages: 13126 - 13135
      Abstract: This article proposes a half-bridge LLC resonant converter applying a simple circuit with a variable magnetizing inductance scheme for hold-up time requirement. By changing the magnetizing inductance of the main transformer, the proposed converter can satisfy the hold-up time requirement without sacrificing efficiency, featuring small conduction, and turn-off switching losses of the primary switches in the nominal status. In addition, the proposed converter can relieve the burden of the additional components by positioning them on the signal path, and the proposed circuit is self-powered by adding only one additional winding instead of the isolated power supply. Therefore, those of the size and cost of the proposed circuit can be reduced compared to the previous studies. The feasibility of the proposed method was verified with a 350 W prototype converter (56 V/6.25 A), and the improved circuit for the transient mode was also presented. The experimental results validated the theoretical analysis and showed the effectiveness of the proposed converter for high-efficiency applications, especially in light-load conditions.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Charge Pump Gate Drive to Reduce Turn-ON Switching Loss of SiC MOSFETs
    • Pages: 13136 - 13147
      Abstract: Turn-on loss is the dominant part of the switching loss for SiC MOSFETs in hard switching. Reducing turn-on loss with conventional voltage source gate drives (VSGs) is difficult because of the limited gate voltage rating and large internal gate resistance of SiC MOSFETs. A charge pump gate drive (CPG) that can reduce the turn-on loss is presented in this article. By precharging the charge-storage capacitor in the gate drive with a charge pump circuit, the gate drive output voltage is pumped up to provide higher gate current during the turn-on transient. As a result, the turn-on time and loss is decreased. Moreover, due to the charge transfer from the charge-storage capacitor to the MOSFET gate capacitance, the pumped output voltage can naturally drop back to a normal value that avoids gate overcharging. The structure of the gate drive is simple, and no additional control is needed. The operation of the proposed CPG is verified with double pulse tests based on SiC MOSFETs. The switching loss of the proposed CPG is reduced by up to 71.7% compared to the conventional VSG at full load condition.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • New Bridgeless Power Factor Correction Converter With Simple Gate Driving
           Circuit and High Efficiency for Server Power Applications
    • Pages: 13148 - 13156
      Abstract: A bidirectional-switch bridgeless power factor correction (PFC) converter (BBPFC) is a fascinating topology for high-power application among various bridgeless PFC (BPFC) converters due to its simple structure and easy control method despite using a floating gate driver. In addition, by varying reverse recovery characteristics of rectifying diodes placed on the conduction path, it is possible to improve common-mode (CM) noise characteristics without additional line filter. However, the BBPFC is difficult to actually use in server power supply product because of high guarantee payment. Thus, in this article, a new BPFC for high efficiency and simple structure without any patent issues is proposed. Moreover, it can be simply implemented since the proposed converter does not require floating gate driver but use a simple bootstrap circuit. Furthermore, in both positive and negative cycles, the proposed converter can have lower power loss characteristics due to utilization of one switch for build-up operation. The proposed converter also uses the relative reverse recovery characteristics resulting in good CM noise characteristics. Thus, the proposed converter can obtain high efficiency and good CM noise characteristics with simple structure and easier control method. The effectiveness of the proposed converter is verified by a prototype in universal input and 800-W/400-V output.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Tapped-Inductor-Based Single-Magnetic Bidirectional PWM Converter
           Integrating Cell Voltage Equalizer for Series-Connected Supercapacitors
    • Pages: 13157 - 13171
      Abstract: Conventional supercapacitor (SC)-based energy storage systems require two separate converters, namely a bidirectional converter and a cell voltage equalizer. Each converter requires magnetic components, hence increasing the complexity, volume, and cost. This article proposes the single-magnetic bidirectional converter integrating a cell voltage equalizer. The proposed integrated converter is derived from the combination of a bidirectional pulsewidth modulation converter with a tapped inductor (TI) and a resonant voltage multiplier (RVM). The RVM is driven by the TI generating a square wave voltage with an arbitrary amplitude. Not only is the system simplified by the integration, but also the single-magnetic topology achieves circuit miniaturization. A 100-W prototype for nine SCs connected in series was built for the experimental charge–discharge cycling test. The voltage mismatch of SCs automatically disappeared during charge–discharge cycling, demonstrating the integrated functions of the proposed converter.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Ultrahigh-Voltage Switch for Bidirectional DC–DC Converter Driving
           Dielectric Elastomer Actuator
    • Pages: 13172 - 13181
      Abstract: Specific applications, such as dielectric elastomer actuators (DEAs) or electroactive polymers, require to switch voltage levels exceeding the ratings of existing semiconductor devices. In low-power application, reversible flyback is widely used to supply DEAs. Lowering the parallel parasitic capacitance of the high-voltage switch is important to improve the energy transfer, while it becomes mandatory to increase the output voltage of flyback above 2.5 kV. In this article, a pulsed transformer gate driver (PTGD) is used to drive series-connected MOSFET and, therefore, push the limits from 4.5 to 16 kV. At these high-voltage levels, the structure reveals a drastic voltage unbalance related to the transformer interwinding parasitic capacitance. The compensation method proposed to achieve voltage balance only adds few passive components and reduces significantly the additional parallel capacitance of the switch compared to common load side voltage balancing methods. Finally, and as proof of concept, a half-bridge bidirectional converter was designed from this switch technology and drove an actual DEA at 16 kV.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • A Review of Switching Oscillations of Wide Bandgap Semiconductor Devices
    • Pages: 13182 - 13199
      Abstract: Wide bandgap (WBG) devices offer the advantages of high frequency, high efficiency, and high power density to power converters due to their excellent performance. However, their low parasitic capacitance and fast switching speed also make them more susceptible to switching oscillations. The switching oscillations can cause voltage and current overshoots, shoot-through, electromagnetic interference, additional power loss, and even device damage, which can seriously affect the performance of power converters and systems. However, a comprehensive and in-depth overview is lacking on this topic. This article reviews the types, the causes and negative effects, the effects of parasitic parameters and suppression methods of these switching oscillations, which is helpful for practical engineering. First, the switching oscillations are divided into different types, and their causes and negative effects are reviewed. Then, the effects of different parasitic parameters on the switching oscillations are overviewed. It is found that due to the different physical structures of silicon carbide metal-oxide-semiconductor field-effect transistors, enhancement-mode gallium nitride high-electron mobility transistors (eGaN HEMTs), and cascode GaN HEMTs, the effects are also different. Finally, the main methods of suppressing the switching oscillations are summarized, and the advantages and disadvantages of these methods are presented. Furthermore, future research works on this topic and the conclusion of this paper are drawn, which will help readers deepen their understanding of the switching oscillations of WBG devices, and inspire readers to better use WBG devices for high-frequency and high-efficient power conversion.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • An Ultrahigh Step-Up Quadratic Boost Converter Based on Coupled-Inductor
    • Pages: 13200 - 13209
      Abstract: In this article, an ultrahigh step-up quadratic boost converter based on coupled-inductor is proposed. The voltage gain of the proposed converter can be enhanced significantly by increasing the duty cycle due to the quadratic boost structure. A coupled-inductor integrated with a voltage doubler cell is applied to further improve conversion ratio and reduce voltage stresses. The leakage inductor current is utilized to achieve zero-current switching for output diode. Meanwhile, high efficiency is possible as the energy of the leakage inductor is recycled and transferred to the load. The operating principle and steady-state analysis are provided, and a 280-W prototype is designed to verify the validity of the proposed converter.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Multicell Reconfigurable Multi-Input Multi-Output Energy Router
    • Pages: 13210 - 13224
      Abstract: This article presents a multicell reconfigurable multi-input multi-output (MR-MIMO) power conversion architecture for multiport applications such as multisource energy router, battery balancer, and photovoltaic optimizer. The MR-MIMO architecture couples a large number of modular dc–ac cells with a single magnetic core which processes multiway bidirectional power flow. The system voltage and current ratings can be linearly extended and reconfigured by connecting the dc–ac cells in series or parallel. The MR-MIMO architecture decouples the voltage rating and current rating of the basic cells, and offers much lower device stress than traditional wide-operation range multiport dc–dc converters. The key contributions of this article include: 1) a multicell reconfigurable 12-winding MIMO converter with high performance across a wide range; 2) a hybrid time-sharing and phase-shift control strategy; and 3) a systematic method of designing multiwinding PCB transformers. The MR-MIMO architecture allows one power converter being used for multiple purposes through software reconfiguration. The work presented in this article proved that it is possible to gain significantly design flexibility in a multicell reconfigurable architecture without sacrificing the efficiency or power density. A 500-W 4-port energy router with 12 modular cells and a 12-winding transformer has been built and tested to verify the effectiveness of the proposed MR-MIMO architecture. The energy router maintains over 95% efficiency across a wide range of input and output voltage options.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Novel High-Efficiency Frequency-Variable Buck–Boost AC–AC Converter
           With Safe-Commutation and Continuous Current
    • Pages: 13225 - 13238
      Abstract: In this article, a novel high-efficiency single-phase frequency-variable buck–boost ac–ac converter is proposed. AC input voltage can be bucked and boosted with step-changed frequency operation. In the topology, only six switches and total ten semiconductors are utilized, which is at the lowest level among existing works. Only two of the switches are operating at high frequency and only one switch is switched on and off in each switching period, Therefore, the proposed converter has less power loss and features high efficiency. With simple and flexible control strategy, the converter is immune of commutation problem and thus no additional safe-commutation strategy or snubber circuit is needed. Power density of proposed converter is high considering the volume metric of the energy storage components. Moreover, the input current of proposed ac–ac converter is continuous. Therefore bulky input filter required by other existing works is totally removed, which further improve the power density. Operation principles and circuit analysis is provided. To verify the performance, a 200-W laboratory prototype is constructed and experiments are conducted in operation of buck and boost mode at step-changed output frequency of 30, 60, and 120 Hz.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • General Method for Synthesizing High Gain Step-Up DC–DC Converters Based
           on Differential Connections
    • Pages: 13239 - 13254
      Abstract: This article introduces a powerful methodology to synthesize high gain step-up dc–dc converters from differential connections of two converters. The two selected converters may be either equal or different, and they can use different kinds of gain cells. Both only have to present a common reference between the input and output voltages and the same output voltage polarity. The proposed differential connection supplies high step-up converters and mainly the method can be applied to synthesize different topologies from different well-known converters. Besides the derivation and analysis of some converters in continuous conduction mode, the article also discusses the power processing, reduction of components, addition of gain cells to further increase the gain, different kinds of modulations, and addresses a different point of view for some topologies previously published in literature. The proposed methodology is verified through thirteen prototypes derived from basic converters considering input voltage of 20 V, duty cycle of 0.75, switching frequency of 50 kHz and rated power of 100 W. Moreover, three new ultrahigh gain dc–dc converters are still derived from the insertion of gain cells in the differential converters herein proposed. These three converters are experimentally evaluated under input voltages of 20 and 30 V, rated power of 200 W and, switching frequency of 50 kHz, providing static gains from 15 up to 30, and peak efficiency of 96.78%.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Selective Torque Harmonic Elimination for Dual Three-Phase PMSMs Based on
           PWM Carrier Phase Shift
    • Pages: 13255 - 13269
      Abstract: Recently, dual three-phase drives have attracted an increasing attention with their high torque density, improved fault tolerance, and direct use of the off-the-shelf three-phase inverters. This article presents a carrier-based algorithm for the selective elimination of high-frequency pulsewidth modulation (PWM) torque harmonics in dual three-phase drives. The PWM control of the power converters is one of the main sources of high-frequency torque ripple in high-power electrical machines. The proposed technique selectively eliminates the torque-ripple harmonic components by applying a proper carrier phase shift between the two three-phase subsystems of the dual three-phase drive, considering the arbitrary phase displacements among the two subwindings. Two case studies of dual three-phase machines with phase displacements of 0 and π/6 are, respectively, analyzed under the most significant carrier phase-shift solutions. The torque performance improvement and the effect on the current ripple introduced by the proposed carrier phase-shifts are presented and validated by means of numerical, finite-element, and experimental results.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Magnetization State Selection Method for Uncontrolled Generator Fault
           Prevention on Variable Flux Memory Machines
    • Pages: 13270 - 13280
      Abstract: Permanent magnet (PM) machine drive system is vulnerable to uncontrolled generator fault (UCGF) when all gating signals are removed from inverter during high-speed operation. Due to the PM flux controllability of variable flux memory machine (VFMM), this article proposes a novel magnetization state selection (MSS) method, which can not only extend the machine speed range effectively but also avoid the overvoltage issue during UCGF process. In the proposed MSS method, the VFMM operates at several different magnetization states (MSs) to reduce the MS changing frequency. The critical speed of each MS is determined by a steady-state UCGF model to restrict the maximum voltage within a safety margin. Consequently, the overvoltage issue of the VFMM can be eliminated during the entire UCGF process. On the other side, the proposed scheme can also realize highly efficient flux weakening for speed range extension with a reduced requirement of d-axis current excitation. Finally, the developed control strategy is verified by experimental measurements on a VFMM prototype.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • An Online Data-Driven Method for Simultaneous Diagnosis of IGBT and
           Current Sensor Fault of Three-Phase PWM Inverter in Induction Motor Drives
    • Pages: 13281 - 13294
      Abstract: This article presents an online data-driven diagnosis method for multiple insulated gate bipolar transistors (IGBTs) open-circuit faults and current sensor faults in the three-phase pulsewidth modulation inverter. The fast Fourier transform (FFT) algorithm is used to extract the fault frequency spectrum features of the three-phase currents. Then, a feature selection method named ReliefF is introduced to select the most critical features by removing redundant and irrelevant features. In addition, as novel fast learning technology, a random vector functional link network is applied to learn the faulty knowledge from the historical dataset. Based on the well-learned model, the fault type and location of the converter can be accurately identified as long as the three-phase current signals are measured. Offline test results verify that the proposed method can identify the IGBT and sensor faults with an accuracy of 98.83% and outperforms the state-of-the-art learning algorithms. Moreover, the real-time hardware-in-the-loop test results show that the proposed method can successfully identify the IGBT faults and current sensor faults within 22 ms. It is robust to the dc-link voltage fluctuations, model parameters, and speed or load variations. The extensibility of the proposed method is also validated based on the test results in terms of other fault modes and drive systems.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • $^circ$ -Clamped+Space+Vector+PWM+Technique+Eliminating+Zero+States+for+EV+Traction+Inverters+With+Dynamic+DC+Link&rft.title=IEEE+Transactions+on+Power+Electronics&rft.issn=0885-8993&rft.date=2020&rft.volume=35&rft.spage=13295&rft.epage=13307">Comprehensive Analysis and Experimental Validation of 240 $^circ$ -Clamped
           Space Vector PWM Technique Eliminating Zero States for EV Traction
           Inverters With Dynamic DC Link
    • Pages: 13295 - 13307
      Abstract: A bus-clamping space vector pulsewidth modulation (PWM) called 240$^circ$-clamped PWM (240CPWM) is analyzed for three-phase converters that have a cascaded connection of a dc–dc stage and a dc–ac stage. A direct application of the proposed concept is electric vehicle (EV) traction inverters that employ a dc–dc stage to interface a relatively low-voltage battery to a high-voltage motor. The 240CPWM method has the major advantages of clamping a phase to the positive or negative rail for 240$^circ$ in a fundamental period, clamping of two phases simultaneously at any given instant, and use of only active states, completely eliminating the use of zero states. These characteristics lead to more than seven times reduction in switching losses of the inverter at unity power factor compared to CSVPWM, comparable or better total harmonic distortion (THD) performance, significant reduction in common-mode voltage and high efficiency. The THD of the line current is analyzed using the notion of stator flux ripple and compared with conventional and discontinuous PWM methods. The switching loss characteristics under different power factor conditions are discussed. Experimental results from a 10-kW hardware prototype are presented. The full load efficiency with the proposed 240CPWM for the dc–ac stage exceeds 99% even with Si insulated-gate bipolar transistors (IGBTs).
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Design and Analysis of Electrical Braking Torque Limit Trajectory for
           Regenerative Braking in Electric Vehicles With PMSM Drive Systems
    • Pages: 13308 - 13321
      Abstract: In this article, an electrical braking torque limit trajectory is designed to improve the regenerative braking of electric vehicles based on a regenerative power analysis. Even though electric motors generally regenerate electric energy from kinetic energy, the drive system dissipates electric energy under certain low-speed operation conditions. This phenomenon has been addressed in many previous works and most of them compensate for this power dissipation region by modifying the electrical braking torque limit trajectory of the motor. However, the torque limit trajectory has never been considered based on a regenerative power analysis even though an inaccurate torque limit trajectory causes energy loss to the drive system. In this article, the regenerative power analysis for two major kinds of permanent magnet synchronous motor is performed. Afterward, torque limit trajectories are set based on this analysis so that batteries in electric vehicles can harvest the maximum regenerative energy in any circumstance. To verify the analysis and proposed torque limit trajectories, simulations and experiments are performed.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • CMOS Active Gate Driver for Closed-Loop dv/dt Control of GaN Transistors
    • Pages: 13322 - 13332
      Abstract: This article shows both theoretical and experimental analyses of a fully integrated CMOS active gate driver (AGD) developed to control the high dv/dt of GaN transistors for both 48 and 400 V applications. To mitigate negative effects in the high-frequency spectrum emission, an original technique is proposed to reduce the dv/dt with lower switching losses compared to classical solutions. The AGD technique is based on a subnanosecond delay feedback loop, which reduces the gate current only during the dv/dt sequence of the switching transients. Hence, the dv/dt and di/dt can be actively controlled separately, and the tradeoff between the dv/dt and EON switching energy is optimized. Since GaN transistors have typical voltage switching times on the order of a few nanoseconds, introducing a feedback loop from the high voltage drain to the gate terminal is quite challenging. In this article, we successfully demonstrate the active gate driving of GaN transistors for both 48 and 400 V applications, with initial open-loop voltage switching times of 3 ns, due to a full CMOS integration. Other methods for dv/dt active control are further discussed. The limits of these methods are explained based on both experimental and simulation results. The AGD showed a clear reduction in the peak dv/dt from –175 to –120 V/ns for the 400 V application.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Low-Noise Initial Position Detection Method for Sensorless Permanent
           Magnet Synchronous Motor Drives
    • Pages: 13333 - 13344
      Abstract: Initial rotor position detection is important to ensure the start-up operation of sensorless permanent magnet synchronous motor (PMSM) drives. In order to suppress the annoying noise caused by the additional signal injection during the detection process in the existing methods, a pseudorandom high-frequency (HF) square-wave voltage injection based low-noise initial position detection method is proposed in this article. Two fixed HF square-wave voltage signals are injected into the estimated d-axis randomly. As the magnetic pole position is detected, the magnetic polarity can be identified at the same time, based on the accumulation of the induced random HF current peak pairs without any extra signal. In addition, a saturated peak current delay compensation strategy is proposed to reduce the digital delay effects on the magnetic polarity detection. The proposed method makes the entire detection process simpler and faster. Furthermore, power spectral density (PSD) analysis of random HF currents is adopted to provide the theoretical support for noise reduction. Finally, the proposed method is verified by experiments on a 2.2-kW interior PMSM drive platform.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Minimization of Additional High-Frequency Torque Ripple for Square-Wave
           Voltage Injection IPMSM Sensorless Drives
    • Pages: 13345 - 13355
      Abstract: The high-frequency (HF) square-wave voltage injection sensorless control method will bring additional HF torque ripple to interior permanent magnet synchronous motor (IPMSM). Focused on this problem, this article analyzes the relationship between the HF response current and the HF torque ripple resulting from HF square-wave voltage injection. It is concluded that when the fluctuation direction of HF response current is vertical to the stator current vector direction at the maximum torque per ampere (MTPA) operating point, the resulting HF torque ripple reaches its minimum. Based on this conclusion, a novel HF square-wave voltage injection sensorless control method is proposed in this article, which can realize the sensorless control and minimize the HF torque ripple at the same time. The injection angle of HF square-wave voltage in the estimated synchronous rotating reference frame is adjusted in real time according to the operating conditions, so that the HF response current always fluctuates along the vertical direction of the stator current vector at the MTPA operating point. Besides, the corresponding demodulation method of the rotor position estimation error is illustrated. Finally, the experiments are performed on a 20-kW IPMSM platform and the results verify the effectiveness of the proposed method.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Analysis and Design of a Low-Cost Well-Performance and Easy-to-Design
           Current Sensing Circuit Suitable for SiC mosfets
    • Pages: 13356 - 13366
      Abstract: Current sense resistor (CSR) is widely used due to cost and integration considerations in industrial applications. However, when CSRs are used to sense transient currents caused by power device switching, especially fast-switching silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (mosfets) with high di/dt, even a tiny parasitic inductance in CSRs bring a significant impact on its sensing performance. This article proposes a low-cost well-performance and easy-to-design current sensing circuit that uses the CSRs and an LR compensation network (LRCN) to compensate for the effect of parasitic inductance on transient current sensing. In order to support the parameter selection of the LR network, the effects of parameters such as parasitic capacitance, parasitic inductance, and loads on the performance of the proposed current sensing circuit are analyzed in detail. Meanwhile, a parasitic inductance measurement method that only needs passive probes is proposed to measure and calculate the parasitic inductance of CSRs. This circuit can not only sense the transient current on the printed circuit board level but also observe the transient current on the oscilloscope through a coaxial cable connection. Finally, experimental studies under an inductive load double pulse test setup with SiC mosfets are carried out to verify the validity and feasibility of the proposed transient current sensing circuit. Only a high self-resonant frequency inductor and a surface mounted device resistor are needed to form the LR network to fully compensate the effect of parasitic inductance on CSRs.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Novel iGSE-C Loss Modeling of X7R Ceramic Capacitors
    • Pages: 13367 - 13383
      Abstract: Due to the large relative permittivity of Class II dielectrics, ceramic capacitors (CCs) from these materials promise significant volume and weight reductions in inverter and rectifier sine-wave filters, and are especially attractive in mobile applications that demand ultrahigh power density. While previous literature found large low-frequency losses in these components, no extensible loss model was proposed to accurately characterize these ferroelectric losses. In this article, we take advantage of prior art on ferromagnetic components in power electronics to propose a Steinmetz parameter-based loss modeling approach for X7R CCs, named the Improved Generalized Steinmetz Equation for CCs, or iGSE-C. This model is verified using the Sawyer–Tower circuit to measure losses in a commercially available X7R capacitor across excitation magnitude, dc bias, temperature, excitation frequency, and harmonic injection. Losses are shown to scale according to a power law with charge, with the resulting Steinmetz coefficients valid across dc bias and slightly varying as the temperature is increased. The iGSE-C accurately predicts losses for typical nonsinusoidal phase voltage waveforms with an error under 8%. Finally, the loss modeling technique is demonstrated for the sine-wave output filter of a bridge-leg arrangement with both low- and high-frequency excitations, with total capacitor losses predicted within 12% accuracy.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Comparative Temperature Dependent Evaluation and Analysis of 1.2-kV SiC
           Power Diodes for Extreme Temperature Applications
    • Pages: 13384 - 13399
      Abstract: Considering potential applications related to superconductivity and aerospace (typically less than 100 K), in this article, the temperature dependence of silicon carbide (SiC) power diodes is systematically characterized and analyzed over a wide temperature range of 90–478 K, especially focusing on cryogenic temperature. First, the static performance degradation mechanism of SiC diodes is established in an ultrawide temperature range, including forward/reverse I-V characteristics and junction capacitance (Cj) characteristics. Second, the reverse recovery characteristics are achieved, including peak reverse recovery current (Irm), reverse recovery charge (Qrr), and switching energy (Esw), clarifying a clearer internal relationship between reverse recovery and junction temperature. Meanwhile, the aforementioned critical parameters are further analyzed on an electrical scale with normal atmosphere temperature, including switching speed range of 62.3–2054.8 A/μs, load current range of 6–30 A, and dc voltage range of 400–1000 V. Third, based on newly proposed power loss analysis method, the continuous operation performance of SiC diodes is quantified and analyzed in actual cryogenic converters. The excellent temperature dependence indicates that SiC diodes have great superiority for extreme applications. Importantly, SiC mosfet's body diode shows the great potential to operate as a freewheeling diode in the compact converter, especially at cryogenic temperature.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Improved Methodology for Parasitic Characterization of High-Performance
           Power Modules
    • Pages: 13400 - 13408
      Abstract: The accelerating commercialization of wide bandgap technology has led to increased demand for accurate characterization of parasitic impedances within packaging structures such as multichip power modules. However, the accuracy of known methods is not sufficient to characterize high-performance modules which have extremely low parasitics, with impedance values near the measurement floor of common instrumentation. To address this characterization gap, this article introduces a custom measurement methodology that utilizes a general-purpose instrument and fixture but reduces systematic and stochastic error to an acceptable level through an emphasis on rigorous calibration and measurement consistency. Additionally, fixture compensation is performed via post-processing in MATLAB to improve measurement fidelity via statistical techniques. The proposed methodology is validated with a series of known test samples in the impedance range of interest. Finally, the methodology is used to perform parasitic characterization of a high-performance power module with commutation loop inductance previously reported to be less than 1.6 nH.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Surge-Energy and Overvoltage Ruggedness of P-Gate GaN HEMTs
    • Pages: 13409 - 13419
      Abstract: An essential ruggedness of power devices is the capability of safely withstanding the surge energy. The surge ruggedness of the GaN high-electron-mobility transistor (HEMT), a power transistor with no or minimal avalanche capability, has not been fully understood. This article unveils the comprehensive physics associated with the surge-energy withstand process and the failure mechanisms of p-gate GaN HEMTs. Two commercial p-gate GaN HEMTs with Ohmic- and Schottky-type gate contacts are studied. Two circuits are developed to study the device surge ruggedness: an unclamped inductive switching circuit is first used to identify the withstand dynamics and failure mechanisms, and a clamped inductive switching circuit with a controllable parasitic inductance is then designed to mimic the surge energy in converter-like switching events. The p-gate GaN HEMT is found to withstand the surge energy through a resonant energy transfer between the device capacitance and the load/parasitic inductance rather than a resistive energy dissipation as occurred in the avalanche. If the device resonant voltage goes below zero, the device reversely turns on and the inductor is discharged. The device failure occurs at the transient of peak resonant voltage and is limited by the device overvoltage capability rather than the surge energy, dV/dt, or overvoltage duration. Almost no energy is dissipated in the resonant withstand process and the device failure is dominated by an electric field rather than a thermal runaway. These results provide critical understandings on the ruggedness of GaN HEMTs and important references for their qualifications and applications.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Nonlinear Compact Thermal Model of the IGBT Dedicated to SPICE
    • Pages: 13420 - 13428
      Abstract: In this article, the problem of modeling the thermal properties of the IGBT using a nonlinear compact thermal model is considered. This model has the form of an electrical network. In the proposed model, the influence of the internal temperature of this transistor on the efficiency of heat dissipation is taken into account. The elaborated model form is presented and the estimation method of this model parameters is described. The correctness of the new model is verified experimentally for different cooling conditions and different values of ambient temperature. Additionally, some results of calculations are compared to the results of calculations performed using selected models given in the literature.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Characterization of a 3.3-kV Si-SiC Hybrid Power Module in Half-Bridge
           Topology for Traction Inverter Application
    • Pages: 13429 - 13440
      Abstract: A state-of-the-art 3.3-kV/450-A hybrid power module for the next generation traction inverter of rolling stock is reported in this paper, combining the silicon (Si) insulated-gate bipolar transistor (IGBT) and silicon carbide Schottky barrier diodes (SBDs) chips. Compared with the existing hybrid technology at the same voltage level, this module is characterized by a half-bridge topology, in which 6 IGBT and 12 SBD chips are integrated in each switch. The outnumbering of the diodes represents a promising mitigation to the low availability of SBDs at this voltage level. Both static and dynamic test of this module and an equivalent Si-based module are carried out comparatively. Apart from describing the features of compactness, low-inductance, and good current distribution among chips, this module is characterized by low turn-on current overshooting and turn-on loss of IGBTs, negligible diode reverse recovery time and loss, as well as flexible allowance of IGBT turn-on current rising rate $boldsymbol{dI}/boldsymbol{dt}$. A parameterized study is carried out to benchmark the advantage of this new topology. Based on the experimental results, the performance of the hybrid module in a three-phase traction inverter circuit is also evaluated by means of electro-thermal simulation. The hybrid module distinguishes itself by describing much lower power loss and junction temperature than its Si-based counterpart.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • A BGR-Recursive Low-Dropout Regulator Achieving High PSR in the Low- to
           Mid-Frequency Range
    • Pages: 13441 - 13454
      Abstract: This article proposes a bandgap reference (BGR) recursive low-dropout (LDO) regulator chip that achieves a high power supply rejection (PSR) in the low- to mid-frequency range. The presented LDO design enables the total PSR of LDO to be free from the finite ripple-rejection of the BGR circuit, resulting in low design complexity and low power consumption. To improve the PSR further, the gate buffer is modified to provide an additional ripple feedforward cancellation. The modified gate buffer also offers fast transient response and stable operation. Moreover, a light-load stabilizer loop is also suggested to provide high stability over all load conditions. A prototype chip able to supply up to 300 mA output current was implemented by 0.5-μm 5-V CMOS devices. The PSR was measured to be –102 to –80 dB at frequencies from 100 Hz to 0.1 MHz, which is higher than that of prior LDOs with COUT ≥ 1 μF. The proposed LDO consumes only 50 μA at a load current of 300 mA, and a peak current efficiency of 99.98% was achieved. The line and load regulations were measured as 0.003%/V and 0.28%/A, respectively. This chip shows a figure-of-merit of 11 ps in the transient response.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • FPGA-Based Continuous Control Set Model Predictive Current Control for
           PMSM System Using Multistep Error Tracking Technique
    • Pages: 13455 - 13464
      Abstract: To overcome the shortcomings of the conventional continuous control set model predictive current control (CCS-MPCC), such as large overshoot and poor robustness, an extended surface-mounted permanent magnet synchronous motor (SPMSM) model-based multistep error tracking CCS-MPCC (MSET-CCSMPCC) is proposed in this article. First, a traditional CCS-MPCC is derived based on the conventional SPMSM model and its robustness is analyzed by considering the parameter mismatches. Second, an extended SPMSM model is given by incorporating the lumped disturbances into one disturbance part. Third, a sliding mode differentiator improved fast terminal sliding mode disturbance observer is designed to track the disturbances. Fourth, by compensating the extended SPMSM model for the estimated d- and q-axes disturbances, an extended SPMSM model-based CCS-MPCC (EXM-CCSMPCC) is designed. However, the EXM-CCSMPCC has serious step response overshoot. Fifth, an extended SPMSM model-based single step error tracking CCS-MPCC is presented, whose dynamic response and steady-state performances deteriorate when the overshoot is reduced. Finally, an MSET-CCSMPCC is proposed to reduce the overshoot and improve the robustness while maintaining excellent dynamic and steady-state performances. Experiments are implemented on a field-programmable gate array based hardware system to verify the excellent performances of the proposed method.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Systematic Design and Optimization Method of Multimode Hybrid Electric
           Vehicles Based on Equivalent Tree Graph
    • Pages: 13465 - 13474
      Abstract: Multimode hybrid electric vehicles (HEVs) have been widely applied due to its high efficiency and excellent overall performance. However, the introduction of multimode HEVs makes it difficult to choose reasonable design factors (architectures, component parameters, and control strategies) and determine correct mode shift rules, which undoubtedly enhances design complexity. To improve the design efficiency and reduce screen difficulty of optimal multimode configurations, a systematic design method is proposed to generate, screen, and optimize multimode HEVs with a single planetary gear. Based on equivalent tree graph method, the novel architectures are first generated. Then, considering mode shift rules and component parameters, requirements of speed and torque in corresponding main mode and minimum shift rule graph of working modes are taken as constraints to complete configuration screening. Finally, the equivalent consumption minimization strategy considering the proposed mode shift rules is put forward to evaluate and optimize energy management. The numerical results show that fuel economy of optimized configurations is improved by at least 22.1%, which proves the effectiveness of proposed systematic design method. Furthermore, it reveals that the multimode configuration can achieve better fuel economy when adopting the appropriate mode shift rule and designing the right arrangement and number of clutches and brakes.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Small Signal Modeling and Design Analysis for Boost Converter With Valley
           V 2 Control
    • Pages: 13475 - 13487
      Abstract: Recently, it has been reported that valley V2 control can be applied to boost converters. However, the actual transient performance and design methodology are not clear due to insufficient knowledge about its small signal model. In this article, a small signal model of valley V2 controlled boost converter is proposed by combining average method and sampled-data method, which is simple and accurate to half the switching frequency. Then, design guidance focused on dynamical performance and stability is provided. Moreover, compensator for the valley V2 controlled boost converter is discussed. The proposed small signal model and design guidelines are verified with experimental results. Results first indicate that for the valley V2 controlled boost converter, the inductor current information is contained in the control loop because of the discontinuous output voltage ripple, which is totally different from that in V2 controlled buck converter. Also, the equivalent series resistance as well as the duty ratio will affect the transient performance to some extent. Moreover, just by using the simple proportional integral compensator, the valley V2 controlled boost converter can be compensated, and it possesses fast transient performance. As for the stability issues, the ramp compensation is useful to eliminate the instability, improving the stability margin.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • A Symmetrical Control Method for Grid-Connected Converters to Suppress the
           Frequency Coupling Under Weak Grid Conditions
    • Pages: 13488 - 13499
      Abstract: The asymmetrical rotating (dq-) frame control leads to frequency coupling dynamics, which tends to bring in harmonic instability. In this article, based on the established complex signal impedance model, the influence of the grid impedance and the frequency coupling on system stability is analyzed. For the phase-locked loop (PLL) mainly affects the q-axis dynamics, it is proposed that the q-axis feedforward and the d-axis compensation control methods to decrease the asymmetric influence caused by the PLL. Similarly, for the dc-link voltage controller mainly affects the d-axis current reference, this article proposes a d-axis feedforward and q-axis compensation method to improve the asymmetry dynamics introduced by the dc-link voltage controller. When the proposed methods are adopted, the components introduced by the PLL and the dc-link voltage controller in the coupling terms are eliminated, thereby achieving the purpose of suppressing the frequency coupling phenomenon and improving the system stability. The theoretical analysis and the experimental results show that the proposed methods are effective.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • A Double-Modulation-Wave PWM for Dead-Time-Effect Elimination and
           Synchronous Rectification in SiC-Device-Based High-Switching-Frequency
    • Pages: 13500 - 13513
      Abstract: The adoption of fast-switching silicon carbide (SiC) devices enables power converters to operate at high switching frequencies (e.g., 100 kHz). However, as a limiting factor at high switching frequencies, the dead-time in the conventional pulsewidth modulation (PWM) can cause significant voltage losses, bring serious low-frequency voltage/current harmonics, and reduce the linear modulation region with lower dc-link voltage utilization. Using the dead-time compensation can effectively eliminate the dead-time effect but further reduce the linear modulation region. The dead-time elimination PWM essentially has no dead-time effect. But due to the abandon of drive pulses for generating synchronous rectification, it has a lower converter efficiency, as well as current jumps at zero-crossings. In this article, to overcome the drawbacks of the conventional PWM and the dead-time elimination PWM, a double-modulation-wave PWM for dead-time-effect elimination and synchronous rectification is therefore proposed, where extra drive pulses for generating synchronous rectification are added based on the dead-time elimination PWM. The added drive pulses can also help with mitigating current jumps at zero-crossings. At last, the proposed PWM is experimentally validated and compared with the conventional PWM and the dead-time elimination PWM at 100 kHz on a three-phase converter with SiC mosfets and SiC Schottky diodes, showing the merits of low voltage losses, low output harmonics, high dc-link voltage utilization, large linear modulation region, and high efficiency.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Multilayer SOH Equalization Scheme for MMC Battery Energy Storage System
    • Pages: 13514 - 13527
      Abstract: It is preferable for the retired batteries to balance their states-of-health (SOH) in the battery energy storage system (BESS) since it can prolong the system lifetime and reduce the maintenance burden. So far, the corresponding balancing techniques mainly focus on either the SOH balancing among packs or the SOH balancing of cells inside a pack. This article further proposes the multilayer SOH equalization scheme to equalize all cells’ SOHs of large-scale BESS by comprehensively combining the pack SOH balancing strategy and the commercial cell equalization techniques. It is noted that the balancing schemes for pack and cell cannot be simply superimposed since packs and cells have totally different connection modes and are equipped with different types of balancing circuits. In specific, the modular multilevel converter (MMC) is assumed to coordinate the pack and cell SOH equalization schemes, where the charging/discharging power per submodule is properly adjusted according to the extent of cell SOH deviation and the extent of pack SOH deviation together. MATLAB simulation and experimental results of a 10-kWh MMC-BESS prototype verified the performance of the proposed method.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Hybrid Modulation Technique With DC-Bus Voltage Control for Multiphase NPC
    • Pages: 13528 - 13539
      Abstract: The article presents a novel carrier-based pulsewidth modulation technique for multiphase neutral point clamped converters. The technique is aimed to actively control the neutral point (NP) potential while supplying the desired set of line-to-line voltages to the load. Standard techniques are either based on the sole common mode voltage injection or on the sole multistep switching mode; contrarily, the proposed algorithm combines these two approaches to take advantage of their main benefits. The technique performs well for each number of phases, for each modulation index, and for each type of load. It can control in closed-loop the NP voltage to any desirable value with a reduced number of switching transitions. The proposed approach has been experimentally validated and compared with other carrier-based algorithms.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Analytic Spectral Analysis Technique for Converters Operating With
           Oscillatory DC-Link Voltage Components
    • Pages: 13540 - 13553
      Abstract: Converters are playing an ever increasing role in electric power grids. To help facilitate a design of power grids that ensures stable and efficient transfer of power, the harmonic pollution injected by converters must be quantified. At present, analytic expressions used to describe modulated converter waveforms have been derived while assuming that the converter dc-link voltage contains only a dc component. This is a reasonable assumption in many converter applications. However, there is a large number of converters that operate with superimposed oscillatory dc-link components, such as single-phase and cascaded multilevel converters. Grid and/or load imbalance can also lead to oscillatory dc-link voltage components. Given this context, the main contribution of this article is to derive analytic expressions for converter output harmonics when oscillatory components are present in the dc-link voltage. Experimental verification of the proposed spectral analysis technique is performed on a $text{1},text{kVA}$, 3-level, $text{240},text{V}$ single-phase full-bridge inverter.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • An Adaptive Sensorless Control Technique for a Flyback-Type Solar Tile
    • Pages: 13554 - 13562
      Abstract: This article presents a novel sensorless control system for a solar tile microinverter employing the flyback topology. The elimination of current sensors from the circuit lowers the overall cost and reduces measurement noise introduced into the control system. The proposed control system eliminates both the high frequency inductor current measurement as well as the photovoltaic (PV) module current measurement. Additionally, an inductance observer is combined with the proposed technique to increase the accuracy of the high frequency inductor current estimation. A stability analysis proves the system to be stable. The proposed control system is experimentally validated on a microinverter prototype. Simulation and experimental results affirm the feasibility and performance of the control system. The experimental setup includes a grid simulator and a PV module simulator to test the system at varying irradiance levels. The proposed control system is also compared to methods presented in previous literature to demonstrate its superior characteristics.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Investigation of Disturbance Observers for Model Predictive Current
           Control in Electric Drives
    • Pages: 13563 - 13572
      Abstract: Model predictive control (MPC) of power electronic converters has obtained much attention in many applications and especially in electric motor control. As the control loop is closed by predicting the future plant behavior by means of a mathematical model, disturbances and uncertainties are important aspects when using any MPC strategy. The plant model may be inaccurate due to plenty of reasons, such as parameter mismatches or the inverter nonlinearity. If these disturbances are not properly addressed during the MPC design process, the control performance is deteriorated. Hence, a suitable disturbance observer (DOB) is required to compensate for model inaccuracies. This contribution is comparing different lumped-DOB designs in the context of a continuous-control set MPC for induction motor current control. As a baseline for comparison, a field-oriented proportional-integral (PI)-type regulator is utilized which does not require a DOB due to its integral feedback.Comprehensive experimental results prove the necessity of a proper DOB; however, it is also shown that the overall transient and steady-state control improvement due to MPC has to be bought at a high price since the computational burden is at least doubled compared to the PI-baseline.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Design of Multifrequency Proportional–Resonant Current Controllers for
           Voltage-Source Converters
    • Pages: 13573 - 13589
      Abstract: In recent years, the applicability of multifrequency proportional–resonant (PR) current controllers has been extensively explored. The analysis and controller design are typically performed by means of frequency response methods. In this context, the open-loop system's gain crossover frequency and the associated phase margin are most commonly used as design parameters. However, those parameters are not well defined in applications with multifrequency PR controllers, where multiple 0-dB crossings of the open-loop gain emerge. In contrast, it is shown that the system's gain margin can mostly be utilized as a reliable stability measure. Furthermore, since each resonator introduces an unwanted phase lag to its higher neighbored resonator, the desired stability margin might not be achieved by “conventional” controller designs or the system could even be destabilized. Hence, this article reviews common analytic design guidelines for PR current controllers and extends them to controllers that implement multiple resonators in either a stationary frame or a synchronous reference frame. To achieve a good compromise between the stability margin and a small steady-state control error, a recursive adjustment procedure for the controller's integral gains is proposed. The “plug-and-play” controller design is applied to a grid-connected voltage-source converter and the theoretical findings are validated by computer simulations and experiments.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Robust Power Sharing Control for Parallel Three-phase Inverters Against
           Voltage Measurement Errors
    • Pages: 13590 - 13601
      Abstract: In islanded microgrids, distributed generations (DGs) have been increasingly employed through parallel voltage source inverters (VSIs). To fully utilize the VSI capacity and avoid overloading, the total load power is expected to be accurately shared among VSIs based on their power ratings. However, it is revealed that even small voltage measurement scaling errors may severely deteriorate the power sharing by injecting positive- and negative-sequence circulating currents. An explicit analysis indicates that this issue cannot be avoided if the conventional voltage-feedback control is adopted with an accurate fundamental voltage tracking ability. To solve this problem, a hybrid feedback and feedforward control is proposed, which makes the power sharing robust against voltage measurement errors. In specific, the feedforward control is utilized to enhance the unbalanced and reactive power sharing by reshaping the VSI fundamental output impedance. Meanwhile, the feedback-based impedance shaping control is also employed to improve the harmonic power sharing. As no communication and sensor error knowledge are required, the proposed control scheme provides a simple but effective solution for decentralized power sharing among parallel three-phase VSIs. Finally, both simulation and experimental results are provided for verification.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Multifunction Control Strategy for Single-Phase AC/DC Power Conversion
           Systems With Voltage-Sensorless Power-Decoupling Function
    • Pages: 13602 - 13620
      Abstract: In this article, a novel voltage-sensorless controller for the single-phase ac/dc power conversion systems with a self-adaptive power-decoupling function is proposed. Existing control strategies for achieving power decoupling usually require additional active switches or extra measurement circuits to a certain power-decoupling controller. By employing the proposed method, the decoupling voltage could be accurately evaluated with the fluctuations of the other measured state variables in the original converter, and the issues of instability and inaccuracy on power-decoupling control under transient conditions could be solved. Furthermore, the proposed control scheme involves a phase-shift modification to improve the power quality as well as achieve accurate power-decoupling reference, which could eliminate the harmonic influence on the original PFC circuit. Finally, a 1.2-kW single-phase PFC prototype using SiC-based semiconductor switching devices is tested to validate the proposed control scheme. The experimental results demonstrate that the power factor of 0.99 with total harmonic distortion around 3%, and a dc-link voltage with 5% ripple could be achieved with the proposed control strategy.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • IoT-Based DC/DC Deep Learning Power Converter Control: Real-Time
    • Pages: 13621 - 13630
      Abstract: Recently, a modularized smart grid (SG) architecture, entitled the Internet of Things (IoT) grid, is developed that accommodates the IoT technology into the dc–dc converters to build a programmable grid with a single voltage bus. This modern architecture can be established with low computing hardware that facilitates the control and management of the IoT-based grids. Due to the uncertainties originated from the integration of the IoT technology and power electronic converters, the deterministic methodologies are unable to precisely model the SG anymore. In response to these challenges, this article addresses a novel adaptive data-driven method based on the active disturbance rejection controller (ADRC) for the voltage regulation of an IoT-based dc–dc buck converter feeding constant power loads. In particular, a deep deterministic policy gradient (DDPG) with the actor-critic architecture is adopted for the online adjusting of the ADRC controller. The established DDPG takes into account the ADRC controller coefficients into the design objective and offers the ADRC controller with the online coefficient setting ability through the neural network learning. The IoT-based system is tested on a real-time testbed with the constrained application protocol protocol and IEEE 802.11 (Wi-Fi) network to assess the applicability of the suggested controller in the presence of network degradations. The impact of both packet loss and interfering traffic on the reduction performance of the DDPG adaptive ADRC controller is investigated, simultaneously. The supremacy of the suggested adaptive data-driven controllers is verified by a comprehensive comparative analysis with the state-of-the-art methodologies.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Grey Wolf Optimization Algorithm Based State Feedback Control for a
           Bearingless Permanent Magnet Synchronous Machine
    • Pages: 13631 - 13640
      Abstract: In this article, an optimal control strategy for a bearingless permanent magnet synchronous machine (BPMSM) drive is proposed. The state feedback control (SFC) based on the grey wolf optimization (GWO) algorithm is applied. As for the BPMSM system, coupling and nonlinearity exist, which hinders the SFC. Hence, the linearization of the BPMSM mathematical model is implemented first. Second, the discretized state model with the augmented integrals of the displacement error and the angular speed error is obtained. Then, the weighting matrices $K_{d}$ are obtained by employing the GWO algorithm. Finally, simulations and experiments are carried out to verify the effectiveness of the proposed method. Comparisons between the controllers with and without the penalty term are conducted. Meanwhile, the proportional-integral (PI) controllers based on the genetic algorithm and the proposed one are compared as well. The results show the superiority of the proposed method reflecting in faster response and no overshoot compared with the PI controllers.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • $LCL$ -Type+Grid-Tied+Inverters+With+Weighted+Average+Current+Method+for+Improved+Injected+Current+Quality+and+Robustness&rft.title=IEEE+Transactions+on+Power+Electronics&rft.issn=0885-8993&rft.date=2020&rft.volume=35&rft.spage=13641&rft.epage=13651">Separate-Structure UDE-Based Current Resonant Control Strategy on
           $LCL$ -Type Grid-Tied Inverters With Weighted Average Current Method for
           Improved Injected Current Quality and Robustness
    • Pages: 13641 - 13651
      Abstract: Due to its effective high-frequency suppression ability, the LCL filter has been widely used between inverters and the grid. However, its resonance causes system instability. The weighted-average current (WAC) strategy has been extensively studied to suppress resonance. By selecting a proper weight factor of the inductor and injected current, the order of the LCL can be reduced to first without resonance in the control loop, which can significantly simplify the controller design. Nevertheless, disturbances and uncertainties in the system will affect the control performance of the inverter. In this article, for a WAC-form LCL grid-tied inverter, a separate-structure uncertainty and disturbance estimator (SUDE) inner-loop control strategy with a zero-phase, low-pass, time-delay FIR filter is designed in the discrete domain to eliminate the influence of disturbances and parameter uncertainties on the system, and a proportional resonant controller is adopted as an outer-loop controller. By using the proposed FIR filter, the performance in the rejection of high-frequency harmonics is improved. Moreover, the stability of the proposed two-degree-of-freedom compound controller is analyzed in detail, and the superiority and effectiveness of its robustness to grid impedance and harmonic rejection are shown. Finally, the proposed strategies are validated on a 2-kW experimental platform.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • High Performance Model Predictive Control for PMSM by Using Stator Current
           Mathematical Model Self-Regulation Technique
    • Pages: 13652 - 13662
      Abstract: Excellent control performance and high robustness under different operating conditions are primary purposes pursued by many model predictive control algorithms. As a model-based control algorithm, the accuracy of the stator current mathematical model has a significant impact on the control performance of the predictive current control (PCC) method. To improve the current tracking accuracy and the robustness against parameter variation, a stator current mathematical model self-regulation strategy, which uses stator current prediction error to calculate parameter changes and design a parameter variation compensation strategy to correct the mathematical model in real-time at each control cycle, based on PCC algorithm is proposed to pursue desired performance. Consequently, the elimination of stator current prediction error, high controlled quality, and better robustness have been achieved in the proposed method. The comparative simulation and experiment results validate the superiority of the proposed method.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Hysteresis Voltage Prediction Control for Multilevel Converter in the
           Series-Form Switch-Linear Hybrid Envelope Tracking Power Supply
    • Pages: 13663 - 13672
      Abstract: Switch-linear hybrid (SLH) envelope tracking (ET) power supply can achieve high efficiency and high tracking bandwidth simultaneously, and it has two typical forms, namely, series-form and parallel-form. In the series-form SLH ET power supply, the switched-mode converter is expected to output a continuous-wave voltage which can track the load voltage accurately to enhance the overall efficiency, and the buck converter with hysteresis voltage control (HVC) can be utilized. However, the output voltage of the buck converter will go over the hysteresis voltage boundaries, degrading the linearity and efficiency of the ET power supply. In this article, the hysteresis voltage prediction control (HVPC) is proposed to mitigate the problem in the HVC for buck converter. Moreover, in order to further increase the efficiency, the multilevel converter (MLC) is adopted instead of the buck converter for reducing the switching frequency and the inductor root-mean-square current, and the corresponding HVPC control strategy is also proposed. A prototype of the series-form SLH ET power supply employing the MLC with HVPC aimed at 5-MHz envelope signal is fabricated in the lab. The measured overall efficiency is 77.5%, a 12% efficiency improvement over that using step-wave switched-mode converter.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Dual-Level Located Feedforward Control for Five-Leg Two-Mover
           Permanent-Magnet Linear Motor Traction Systems
    • Pages: 13673 - 13686
      Abstract: Based on the model predictive current control (MPCC), a dual-level located feedforward control (DLFC) is proposed for the five-leg dual-mover primary permanent-magnet linear motor traction system, in which, two three-phase movers are fed by one five-leg voltage-source inverter (VSI). In the proposed DLFC, the studied traction system is divided into dual-level subsystems, including mover level and system level. In the mover level, it is assumed that one mover is fed by one three-leg VSI. The reference synchronous currents are replaced by the reference static voltages, and the model current predictions are eliminated by the discrete mover voltage vectors (MVVs). Furthermore, the global optimal MVVs are determined by the mover-level geometrical location. If the implementation conflicts between two global optimal MVVs, two local optimal MVVs will be determined by the system-level geometrical location to replace one former global optimal MVV. Compared with MPCC, the computation burden of DLFC can be significantly reduced. If both control methods use the same sampling period, they have the same performances. On the other hand, DLFC can use shorter sampling period, and it can perform better than MPCC. All the theoretical analyses are verified by simulation and experimental results.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Development and Verification Test of the 6.6-kV 200-kVA Transformerless
           SDBC-Based STATCOM Using SiC-MOSFET Modules
    • Pages: 13687 - 13696
      Abstract: This article discusses development and verification test results of the 6.6-kV 200-kVA transformerless static synchronous compensator (STATCOM). This STATCOM is characterized by the use of a modular multilevel single-delta bridge-cell (SDBC) converter and silicon carbide metal-oxide-semiconductor field-effect transistor (MOSFET) modules. The article discusses a control method for the 6.6-kV system with focus on dc-capacitor voltage control. The voltage control presented in this article is different from the ones presented earlier. It consists of intercluster balancing control and intracluster balancing control. The former, also known as cluster balancing control, eliminates the requirement of the separate overall dc-voltage control present in conventional methods, whereas the latter, also known as individual balancing control, is replaced with a new technique based on the control of a dead time of each bridge cell. The article makes a detailed description of the latter. Experimental results obtained from the 6.6-kV 200-kVA verification test equipment validate the effectiveness of the control method. Moreover, successful test results confirm the efficacy of the system for grid-voltage regulation and load compensation.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Effective Current Limitation for Multifrequency Current Control With
           Distortion-Free Voltage Saturation and Antiwindup
    • Pages: 13697 - 13713
      Abstract: In three-phase converters, it is frequently important to control current components other than the positive-sequence fundamental. Adequate voltage saturation and antiwindup (VSA) should also be included to prevent malfunction under output-voltage saturation due to, e.g., large voltage disturbances or dc-link-voltage reduction. A multifrequency VSA technique was recently proposed, based on modifying the current references so that the control output voltage is brought back to within the hexagonal boundary. Thus, it avoids the additional distortion that would arise if the control output surpassed (even partially) the hexagon. However, no current limitation was considered. If the current references demanded by the VSA are saturated, windup of the integrator contained in said VSA scheme may occur. Furthermore, current saturation also causes steady-state overmodulation; then, the actual current differs from that fed back to the control (due to the internal-model-control structure included in the VSA), and hence it is not effectively limited. This article adds current-saturation functionality to the multifrequency VSA by several relevant modifications. Windup of the integrator of the VSA when current saturation occurs is prevented. The actual current is effectively limited to the desired value also when there is steady-state overmodulation. Experimental results with a three-phase permanent-magnet machine are provided.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • An Event-Driven Resilient Control Strategy for DC Microgrids
    • Pages: 13714 - 13724
      Abstract: Though recent advancements in dc microgrids are largely based on distributed control strategies to enhance reliability, their susceptibility to cyber attacks still remains a challenging issue. Additionally in converter-dominated dc microgrids, mitigation of cyber attacks upon detection in a timely manner is the need of the hour to prevent the system from immediate shutdown. Since most of the existing research is primarily focused on the detection of cyber attacks in dc microgrids without giving prior attention to comprehensive steps of mitigation, this article classifies cyber attacks as events and introduces an event-driven cyber attack resilient strategy for dc microgrids, which immediately replaces the attacked signal with a trusted event-driven signal constructed using True transmitted measurements. This mechanism not only disengages the attack element from the control system, but also replaces it with an event-triggered estimated value to encompass normal consensus operation during both steady state as well as transient conditions even in the presence of attacks. Finally, the event detection criteria and its sensitivity are theoretically verified and validated using simulation and experimental conditions in the presence of both stealth voltage and current attacks.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Variable Switching Periods Based Space Vector Phase-Shifted Modulation for
           DAB Based Three-Phase Single-Stage Isolated AC–DC Converter
    • Pages: 13725 - 13734
      Abstract: The maximum phase current (the maximum transfer power) of the dual-active-bridge based three-phase single-stage (DAB-3P1S) ac–dc converter with the present dual-period-decoupled space vector phase-shifted modulation (DPD-SVPSM) is analyzed for the first time in this article. It shows the equal switching period assignment way of the present DPD-SVPSM reduces the utilization of the control period, thus limiting the maximum transfer power of DAB-3P1S ac–dc converter. To enhance the maximum transfer power, a variable switching period based dual-period-decoupled space vector phase-shifted modulation (VDPD-SVPSM) is proposed. Besides, the current stress of DPD-SVPSM and VDPD-SVPSM are analyzed and compared. And it indicates that by properly designing the transformer leakage inductor, VDPD-SVPSM improves the maximum phase current (maximum transfer power) without increasing the current stress of the device, thereby improving the utilization of the system hardware rated capacity then increasing the power density. Detailed experimental results validate the correctness of the theoretical analysis and the feasibility of the proposed VDPD-SVPSM.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Control Conflict Suppressing and Stability Improving for an MMC
           Distributed Control System
    • Pages: 13735 - 13747
      Abstract: Compared with traditional centralized control strategies, the distributed control systems significantly improve the flexibility and expandability of an modular multilevel converter (MMC). However, the stability issue in the MMC distributed control system with the presence of control loop coupling interactions is rarely discussed in existing research works. This article is to improve the stability of an MMC distributed control system by inhibiting the control conflict due to the coupling interactions among control loops with incomplete control information. By modeling the MMC distributed control system, the control loop coupling interactions are analyzed and the essential cause of control conflict is revealed. Accordingly, a control parameter design principle is proposed to effectively suppress the disturbances from the targeted control conflict and improve the MMC system stability. The rationality of the theoretical analysis and the effectiveness of the control parameter design principle are confirmed by simulation and experimental results.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
  • Soft-Switching Techniques for Single-Inductor Multiple-Output LED Drivers
    • Pages: 13748 - 13756
      Abstract: Although a plethora of prior-art single-inductor multiple-output (SIMO) light-emitting diode (LED) drivers have been reported, they remain inadequate for resource-constraint drone applications due to compromised power efficiency and weight. This article proposes a monolithic SIMO red–green–blue–white LED driver that features high power efficiency and light weight. The former is obtained by employing our proposed soft-switched cross-current-eliminated controller and proposed on-chip bidirectional current sensor. The latter is achieved by means of employing a tiny inductor attributed to boundary conduction mode and high switching frequency. To the best of authors’ knowledge, the proposed SIMO LED driver is the first-ever design that features soft switching for all power switches and innate elimination of current cross-regulation. In comparison with the state-of-the-art designs listed in the benchmark table, the proposed design features the highest power efficiency of 96.2%, smallest output inductor of 820 nH, shortest LED current settling time of 900 ns, and the highest switching frequency of 2 MHz.
      PubDate: Dec. 2020
      Issue No: Vol. 35, No. 12 (2020)
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Heriot-Watt University
Edinburgh, EH14 4AS, UK
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