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  Subjects -> ELECTRONICS (Total: 154 journals)
Showing 1 - 200 of 277 Journals sorted alphabetically
Advances in Biosensors and Bioelectronics     Open Access   (Followers: 6)
Advances in Electrical and Electronic Engineering     Open Access   (Followers: 1)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Microelectronic Engineering     Open Access   (Followers: 11)
Advances in Power Electronics     Open Access   (Followers: 20)
Aerospace and Electronic Systems, IEEE Transactions on     Hybrid Journal   (Followers: 200)
American Journal of Electrical and Electronic Engineering     Open Access   (Followers: 23)
Annals of Telecommunications     Hybrid Journal   (Followers: 7)
Archives of Electrical Engineering     Open Access   (Followers: 12)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 7)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 23)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 16)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 31)
Biomedical Instrumentation & Technology     Hybrid Journal   (Followers: 6)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
BULLETIN of National Technical University of Ukraine. Series RADIOTECHNIQUE. RADIOAPPARATUS BUILDING     Open Access   (Followers: 1)
Bulletin of the Polish Academy of Sciences : Technical Sciences     Open Access  
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 40)
China Communications     Full-text available via subscription   (Followers: 7)
Circuits and Systems     Open Access   (Followers: 13)
Consumer Electronics Times     Open Access   (Followers: 6)
Control Systems     Hybrid Journal   (Followers: 89)
Edu Elektrika Journal     Open Access  
Electronic Design     Partially Free   (Followers: 72)
Electronic Markets     Hybrid Journal   (Followers: 8)
Electronic Materials Letters     Hybrid Journal   (Followers: 1)
Electronics     Open Access   (Followers: 56)
Electronics and Communications in Japan     Hybrid Journal   (Followers: 8)
Electronics For You     Partially Free   (Followers: 60)
Electronics Letters     Hybrid Journal   (Followers: 23)
Embedded Systems Letters, IEEE     Hybrid Journal   (Followers: 40)
Energy Harvesting and Systems : Materials, Mechanisms, Circuits and Storage     Hybrid Journal   (Followers: 3)
Energy Storage Materials     Full-text available via subscription   (Followers: 1)
EPJ Quantum Technology     Open Access  
EURASIP Journal on Embedded Systems     Open Access   (Followers: 13)
Facta Universitatis, Series : Electronics and Energetics     Open Access  
Foundations and Trends® in Communications and Information Theory     Full-text available via subscription   (Followers: 7)
Foundations and Trends® in Signal Processing     Full-text available via subscription   (Followers: 5)
Frequenz     Hybrid Journal   (Followers: 1)
Frontiers of Optoelectronics     Hybrid Journal   (Followers: 1)
Geoscience and Remote Sensing, IEEE Transactions on     Hybrid Journal   (Followers: 128)
Haptics, IEEE Transactions on     Hybrid Journal   (Followers: 3)
IEEE Antennas and Propagation Magazine     Hybrid Journal   (Followers: 52)
IEEE Antennas and Wireless Propagation Letters     Hybrid Journal   (Followers: 42)
IEEE Journal of Emerging and Selected Topics in Power Electronics     Hybrid Journal   (Followers: 29)
IEEE Journal of the Electron Devices Society     Open Access   (Followers: 8)
IEEE Journal on Exploratory Solid-State Computational Devices and Circuits     Hybrid Journal   (Followers: 1)
IEEE Power Electronics Magazine     Full-text available via subscription   (Followers: 46)
IEEE Transactions on Antennas and Propagation     Full-text available via subscription   (Followers: 43)
IEEE Transactions on Automatic Control     Hybrid Journal   (Followers: 46)
IEEE Transactions on Circuits and Systems for Video Technology     Hybrid Journal   (Followers: 15)
IEEE Transactions on Consumer Electronics     Hybrid Journal   (Followers: 31)
IEEE Transactions on Electron Devices     Hybrid Journal   (Followers: 13)
IEEE Transactions on Information Theory     Hybrid Journal   (Followers: 22)
IEEE Transactions on Power Electronics     Hybrid Journal   (Followers: 51)
IEEE Transactions on Signal and Information Processing over Networks     Full-text available via subscription   (Followers: 7)
IEICE - Transactions on Electronics     Full-text available via subscription   (Followers: 13)
IEICE - Transactions on Information and Systems     Full-text available via subscription   (Followers: 7)
IET Microwaves, Antennas & Propagation     Hybrid Journal   (Followers: 14)
IET Power Electronics     Hybrid Journal   (Followers: 26)
IET Wireless Sensor Systems     Hybrid Journal   (Followers: 17)
IETE Journal of Education     Open Access   (Followers: 4)
IETE Journal of Research     Open Access   (Followers: 10)
IETE Technical Review     Open Access   (Followers: 11)
Industrial Electronics, IEEE Transactions on     Hybrid Journal   (Followers: 31)
Industry Applications, IEEE Transactions on     Hybrid Journal   (Followers: 7)
Informatik-Spektrum     Hybrid Journal   (Followers: 1)
Instabilities in Silicon Devices     Full-text available via subscription  
Intelligent Transportation Systems Magazine, IEEE     Full-text available via subscription   (Followers: 8)
International Journal of Advanced Research in Computer Science and Electronics Engineering     Open Access   (Followers: 16)
International Journal of Advances in Telecommunications, Electrotechnics, Signals and Systems     Open Access   (Followers: 7)
International Journal of Antennas and Propagation     Open Access   (Followers: 9)
International Journal of Applied Electronics in Physics & Robotics     Open Access   (Followers: 4)
International Journal of Computational Vision and Robotics     Hybrid Journal   (Followers: 4)
International Journal of Computer & Electronics Research     Full-text available via subscription   (Followers: 1)
International Journal of Control     Hybrid Journal   (Followers: 13)
International Journal of Electronics     Hybrid Journal   (Followers: 3)
International Journal of Electronics & Data Communication     Open Access   (Followers: 10)
International Journal of Electronics and Telecommunications     Open Access   (Followers: 12)
International Journal of Granular Computing, Rough Sets and Intelligent Systems     Hybrid Journal   (Followers: 2)
International Journal of High Speed Electronics and Systems     Hybrid Journal  
International Journal of Image, Graphics and Signal Processing     Open Access   (Followers: 9)
International Journal of Nano Devices, Sensors and Systems     Open Access   (Followers: 6)
International Journal of Nanoscience     Hybrid Journal   (Followers: 1)
International Journal of Numerical Modelling:Electronic Networks, Devices and Fields     Hybrid Journal   (Followers: 3)
International Journal of Power Electronics     Hybrid Journal   (Followers: 13)
International Journal of Review in Electronics & Communication Engineering     Open Access   (Followers: 4)
International Journal of Sensors, Wireless Communications and Control     Hybrid Journal   (Followers: 7)
International Journal of Systems, Control and Communications     Hybrid Journal   (Followers: 4)
International Journal of Wireless and Microwave Technologies     Open Access   (Followers: 5)
International Journal on Communication     Full-text available via subscription   (Followers: 12)
International Journal on Electrical and Power Engineering     Full-text available via subscription   (Followers: 8)
International Transaction of Electrical and Computer Engineers System     Open Access   (Followers: 2)
Journal of Biosensors & Bioelectronics     Open Access   (Followers: 3)
Journal of Advanced Dielectrics     Open Access   (Followers: 1)
Journal of Artificial Intelligence     Open Access   (Followers: 8)
Journal of Circuits, Systems, and Computers     Hybrid Journal   (Followers: 2)
Journal of Computational Intelligence and Electronic Systems     Full-text available via subscription   (Followers: 1)
Journal of Electrical and Electronics Engineering Research     Open Access   (Followers: 16)
Journal of Electrical Bioimpedance     Open Access   (Followers: 2)
Journal of Electrical Engineering & Electronic Technology     Hybrid Journal   (Followers: 7)
Journal of Electromagnetic Analysis and Applications     Open Access   (Followers: 6)
Journal of Electromagnetic Waves and Applications     Hybrid Journal   (Followers: 5)
Journal of Electronic Design Technology     Full-text available via subscription   (Followers: 5)
Journal of Electronics (China)     Hybrid Journal   (Followers: 4)
Journal of Energy Storage     Full-text available via subscription  
Journal of Field Robotics     Hybrid Journal   (Followers: 2)
Journal of Guidance, Control, and Dynamics     Full-text available via subscription   (Followers: 122)
Journal of Intelligent Procedures in Electrical Technology     Open Access   (Followers: 3)
Journal of Low Power Electronics     Full-text available via subscription   (Followers: 7)
Journal of Low Power Electronics and Applications     Open Access   (Followers: 4)
Journal of Microwaves, Optoelectronics and Electromagnetic Applications     Open Access   (Followers: 9)
Journal of Nuclear Cardiology     Hybrid Journal  
Journal of Optoelectronics Engineering     Open Access   (Followers: 2)
Journal of Physics B: Atomic, Molecular and Optical Physics     Hybrid Journal   (Followers: 31)
Journal of Power Electronics & Power Systems     Full-text available via subscription   (Followers: 8)
Journal of Semiconductors     Full-text available via subscription   (Followers: 3)
Journal of Sensors     Open Access   (Followers: 20)
Journal of Signal and Information Processing     Open Access   (Followers: 8)
Jurnal Rekayasa Elektrika     Open Access  
Learning Technologies, IEEE Transactions on     Hybrid Journal   (Followers: 14)
Magnetics Letters, IEEE     Hybrid Journal   (Followers: 7)
Metrology and Measurement Systems     Open Access   (Followers: 4)
Microelectronics and Solid State Electronics     Open Access   (Followers: 14)
Nanotechnology Magazine, IEEE     Full-text available via subscription   (Followers: 32)
Nanotechnology, Science and Applications     Open Access   (Followers: 4)
Networks: an International Journal     Hybrid Journal   (Followers: 5)
Open Journal of Antennas and Propagation     Open Access   (Followers: 4)
Optical Communications and Networking, IEEE/OSA Journal of     Full-text available via subscription   (Followers: 13)
Paladyn, Journal of Behavioral Robotics     Open Access  
Progress in Quantum Electronics     Full-text available via subscription   (Followers: 7)
Pulse     Full-text available via subscription   (Followers: 5)
Radiophysics and Quantum Electronics     Hybrid Journal   (Followers: 2)
Recent Patents on Electrical & Electronic Engineering     Full-text available via subscription   (Followers: 9)
Recent Patents on Telecommunications     Full-text available via subscription   (Followers: 2)
Research & Reviews : Journal of Embedded System & Applications     Full-text available via subscription   (Followers: 4)
Security and Communication Networks     Hybrid Journal   (Followers: 3)
Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of     Hybrid Journal   (Followers: 48)
Semiconductors and Semimetals     Full-text available via subscription   (Followers: 1)
Sensing and Imaging : An International Journal     Hybrid Journal   (Followers: 2)
Services Computing, IEEE Transactions on     Hybrid Journal   (Followers: 5)
Software Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 57)
Solid-State Circuits Magazine, IEEE     Hybrid Journal   (Followers: 10)
Solid-State Electronics     Hybrid Journal   (Followers: 7)
Superconductor Science and Technology     Hybrid Journal   (Followers: 2)
Synthesis Lectures on Power Electronics     Full-text available via subscription   (Followers: 2)
Technical Report Electronics and Computer Engineering     Open Access  
Telematique     Open Access  
TELKOMNIKA (Telecommunication, Computing, Electronics and Control)     Open Access   (Followers: 6)
Universal Journal of Electrical and Electronic Engineering     Open Access   (Followers: 6)
Visión Electrónica : algo más que un estado sólido     Open Access  
Wireless and Mobile Technologies     Open Access   (Followers: 5)
Women in Engineering Magazine, IEEE     Full-text available via subscription   (Followers: 12)
Електротехніка і Електромеханіка     Open Access  

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Journal Cover IEEE Transactions on Power Electronics
  [SJR: 3.005]   [H-I: 160]   [51 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0885-8993
   Published by IEEE Homepage  [192 journals]
  • IEEE Power Electronics Society
    • Abstract: Provides a listing of the editorial board, current staff, committee members and society officers.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • IEEE Power Electronics Society
    • Abstract: Provides a listing of the editorial board, current staff, committee members and society officers.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Start-Up Operation of a Modular Multilevel Converter With Flying Capacitor
    • Authors: Apparao Dekka;Bin Wu;Navid R. Zargari;
      Pages: 5873 - 5877
      Abstract: The three-level flying capacitor (3L-FC) submodule significantly reduces the magnitude of circulating currents, voltage ripple, and footprint size and improves the efficiency of the modular multilevel converter (MMC). Due to the above advantages, the 3L-FC submodule becomes an alternative for the conventional half-bridge submodule in the MMC. Each 3L-FC submodule consists of two floating capacitors with different nominal voltage rating. The precharging of floating capacitors without inrush current is one of the major challenges in the 3L-FC-based MMC. This paper proposes a sequence of design steps to precharge the floating capacitors in the 3L-FC-based MMC. The proposed approach is highly effective to charge the outer and inner capacitors of each 3L-FC submodule to their nominal value. The superiority of the proposed approach is verified through the MATLAB simulations and dSPACE/DS1103 experiments on a laboratory prototype of the 3L-FC-based MMC.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Voltage-Balancing Approach With Improved Harmonic Performance for Modular
           Multilevel Converters
    • Authors: Apparao Dekka;Bin Wu;Ricardo Lizana Fuentes;Marcelo Perez;Navid R. Zargari;
      Pages: 5878 - 5884
      Abstract: In a modular multilevel converter (MMC), the voltage balance among the submodules is mandatory to generate the multilevel stepped waveform across the load and to ensure the equal voltage stress on the semiconductor devices. In addition, the output power quality (voltage and current waveforms) and the converter reliability greatly depend on the design methodology of a voltage-balancing approach. The improper design of the balancing approach causes higher voltage and current harmonic distortion and device power losses, which further affects the efficiency of the MMC. In this letter, an improved voltage-balancing approach is proposed to reduce the output voltage harmonic distortion and device power losses. The performance of the proposed approach is verified through MATLAB simulations and experimentally on a three-level-flying-capacitor-based MMC system. Also, the performance of the proposed approach is compared with the existing methodology to prove its superiority.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Small-Signal Equivalent Circuit Model of Quasi-Square-Wave Flyback
    • Authors: Zhemin Zhang;Shuilin Tian;Khai D. T. Ngo;
      Pages: 5885 - 5888
      Abstract: One benefit of switching a converter at very high frequencies-even to the multimegahertz range-is that the loop bandwidth can be increased so that the transient performance is significantly improved. However, using the conventional small-signal model of continuous conduction mode (CCM) for quasi-square-wave (QSW) converters introduces a huge mismatch for the placement of the dominant poles when compared to the experiment results. The double poles in high-frequency QSW converters are split widely which cannot be predicted by the conventional model. A modified small-signal model of the QSW flyback converter is proposed to predict the double-pole splitting phenomenon and to analytically quantify the damping effect. The impacts of deadtime on control-to-output transfer function have been investigated in detail. The conventional CCM model turns out to be a special case of the proposed model. The theoretical analyses were eventually verified by Simplis simulation and experimental results on a 5-MHz QSW flyback converter.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Voltage-Controlled Capacitor—Feasibility Demonstration in
           DC–DC Converters
    • Authors: Lujie Zhang;Andrew Ritter;Craig Nies;Suman Dwari;Ben Guo;Shashank Priya;Rolando Burgos;Khai Ngo;
      Pages: 5889 - 5892
      Abstract: This letter presents a voltage-controlled capacitor that varies from 20% to 100% of the rated capacitance (1 μF) with a control voltage from half of the voltage rating to 0 V. Capacitance, self-resonant frequency, and equivalent series resistance were measured with respect to the control voltage. An equivalent circuit and a nonlinear model derived from relationship between permittivity and electric field were created and implemented in SPICE. A buck converter with input of 12 V, output of 5 V, and switching frequency of 500 kHz was built to demonstrate the change from 85% to 40% of the rated capacitance of the voltage-controlled capacitor. The error between the simulation and experiment was limited within 10%, which verifies the model.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • A Two-Terminal Active Capacitor
    • Authors: Haoran Wang;Huai Wang;
      Pages: 5893 - 5896
      Abstract: This letter proposes a concept of two-terminal active capacitor implemented by power semiconductor switches and passive elements. The active capacitor has the same level of convenience as a passive one with two power terminals only. It is application independent and can be specified by rated voltage, ripple current, equivalent series resistance, and operational frequency range. The concept, control method, self-power scheme, and impedance characteristics of the active capacitor are presented. A case study of the proposed active capacitor for a capacitive dc-link application is discussed. The results reveal a significantly lower overall energy storage of passive elements and a reduced cost to fulfill a specific reliability target, compared to a passive capacitor solution. Proof-of-concept experimental results are given to verify the functionality of the proposed capacitor.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Inductive Power Transfer for Massive Electric Bicycles Charging Based on
           Hybrid Topology Switching With a Single Inverter
    • Authors: Ruikun Mai;Yang Chen;Yong Li;Youyuan Zhang;Guangzhong Cao;Zhengyou He;
      Pages: 5897 - 5906
      Abstract: It is more convenient and safer to employ inductive power transfer (IPT) systems to charge the battery pack of electric bicycles (EBs) than conventional plug-in systems. An IPT charging method suitable for charging massive EBs is proposed to achieve constant current (CC) and constant voltage (CV) output without feedback control strategies or communication link between transmitter side and receiver side. Two ac switches (ACSs) and an auxiliary capacitor utilized at receiver side are employed to be operated once to change the charging modes from CC mode to CV mode. The characteristics of the load-independent current output in the CC mode and load-independent voltage output in the CV mode are achieved by properly selecting the passive parameters of inductances and capacitors, so that no sophisticated control strategies are required to regulate the output as per the charging profile. The feasibility of proposed method has been verified with an experimental prototype in form of efficiency, stability of output current and voltage in CC/CV mode. The simple and economical approach is suitable for the massive EBs charging system with only one inverter, especially in China.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Modeling of VSC-Based Power Systems in the Extended Harmonic Domain
    • Authors: Miguel Esparza;Juan Segundo-Ramírez;Jun Bum Kwon;Xiongfei Wang;Frede Blaabjerg;
      Pages: 5907 - 5916
      Abstract: Averaged modeling is a commonly used approach used to obtain mathematical representations of VSC-based systems. However, essential characteristics mainly related to the modulation process and the harmonic distortion of the signals are not able to be accurately captured and analyzed. The extended harmonic domain (EHD) has recently been seen as an alternative modeling framework since it allows us to consider the harmonic interaction explicitly. However, there is not a clearly established methodology to derive the EHD models in the presence of power electronic switches. This paper presents a generalized methodology based on the switching instants to obtain large-signal EHD models of VSC-based power systems. Three model order reduction approaches are also proposed to address the increased size of the resulting EHD models. Analytic formulas of three modulation techniques: sinusoidal pulse-width modulation, third harmonic injection pulse-width modulation, and space vector pulse-width modulation are provided to obtain the open-loop large signal EHD models. A performance assessment of the proposed modeling approach in respect to model size, the computational time and the accuracy is presented based on simulations and experimental case studies. The obtained results show that the resulting EHD models are accurate and reliable, while the memory and computation time are improved with the proposed model order reductions.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Zero-Voltage-Transition Interleaved Boost Converter With an Auxiliary
           Coupled Inductor
    • Authors: Je-Hyun Yi;Wooin Choi;Bo-Hyung Cho;
      Pages: 5917 - 5930
      Abstract: This paper proposes a soft-switched interleaved boost converter with minimal conduction loss increment and removed reverse-recovery problem. The soft-switching operation is enabled by a soft-switching cell composed of passive components in which an auxiliary coupled inductor and a dc-link capacitor are connected between the switch legs of the interleaved boost modules and output stage. Every MOSFET switch of the proposed boost converter operates with zero-voltage switching turn-on using the coupled inductor current. Consequently, the switching loss of the proposed interleaved boost converter is greatly reduced. In addition, the reduced circulating current in the auxiliary circuit minimizes the increment of the conduction loss. The proposed soft-switched interleaved boost converter operation is verified with 500-W experimental results.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Low-Voltage-Ride-Through (LVRT) Control of an HVDC Transmission System
           Using Two Modular Multilevel DSCC Converters
    • Authors: Kota Oguma;Hirofumi Akagi;
      Pages: 5931 - 5942
      Abstract: This paper presents an intensive discussion on a high-voltage direct-current (HVDC) long-distance transmission system combining two modular multilevel double-star chopper-cells (DSCC) converters with dc power cables. Hereinafter, each converter is referred to simply as a DSCC converter, or just as a DSCC for more simplicity. Such an HVDC transmission system is required to provide low-voltage-ride-through (LVRT) capability to enhance system availability. This paper proposes a practical LVRT control characterized by the use of power-line communications between the two DSCC converters. The validity and effectiveness of the LVRT control is verified not only by simulated waveforms obtained from the software package “PSCAD/EMTDC” but also by experimental waveforms from a three-phase 200-V, 400-Vdc, 10-kW, 50-Hz downscaled system with 300-m-long dc power cables.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Design Consideration and Comparison of Wireless Power Transfer via
           Harmonic Current for PHEV and EV Wireless Charging
    • Authors: Hulong Zeng;Shuitao Yang;Fang Z. Peng;
      Pages: 5943 - 5952
      Abstract: Wireless power transfer (WPT) using only harmonic current for plug-in hybrid electric vehicle and electric vehicle is a fairly new concept. The frequency limitation of most high-voltage high-current IGBTs is around 20 kHz which also limits the system frequency of the transformer. The series resonant converter (SRC) is widely used in WPT application for its simplicity and high efficiency. Due to the bandpass filter characteristic of the resonant network, the SRC allows one frequency component to pass while the other frequency components are greatly attenuated. By deliberately selecting one harmonic current as the power carrier, the system frequency can be raised up to several times with the same switching frequency. Thus, a higher system frequency contributes to a more compact system. However, a high-order harmonic system results in high conduction loss on the switches, and it leads to a tradeoff between the system size and efficiency. This paper provides a theoretical and practical design for a system using harmonic current. Furthermore, a comprehensive comparison between different harmonic systems is carried out. A 1-kW SRC prototype with a 20-cm air gap is built to verify the proposed method.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Circuit Design Techniques for Reducing the Effects of Magnetic Flux on
           GaN-HEMTs in 5-MHz 100-W High Power-Density LLC Resonant DC–DC
    • Authors: Akinori Hariya;Tomoya Koga;Ken Matsuura;Hiroshige Yanagi;Satoshi Tomioka;Yoichi Ishizuka;Tamotsu Ninomiya;
      Pages: 5953 - 5963
      Abstract: This paper presents circuit design techniques for reducing the effects of magnetic flux, occurred from the planar transformer, on gallium nitride high-electron-mobility transistors (GaN-HEMTs) in 5-MHz 100-W high power-density LLC resonant dc-dc converters. For investigating the effects of magnetic flux on a GaN-HEMT, power device model for finite element method (FEM) simulation is proposed. In order to confirm the validity of the model, the quantitative evaluation is conducted with FEM simulation, and experiment using evaluation boards. Moreover, the optimization of printed circuit board layout is considered using the verified model with FEM simulation, for reducing the effects of magnetic flux on GaN-HEMTs while reducing the area of converter. In the experiments, 5-MHz 48 V/12 V 100 W unregulated LLC resonant dc-dc converter with efficient power conversion GaN-HEMTs is built as the prototype to verify the optimized layout. The maximum power efficiency can be achieved 91.28%, and the power density can be achieved 32 W/cm3.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • A Novel STATCOM Based on Diode-Clamped Modular Multilevel Converters
    • Authors: Xiangdong Liu;Jingliang Lv;Congzhe Gao;Zhen Chen;Si Chen;
      Pages: 5964 - 5977
      Abstract: A new static synchronous compensator (STATCOM) based on the diode-clamped modular multilevel converter (DCM2 C) is proposed in this paper. In this converter topology, the capacitor voltage is clamped by using a low power rating diode in each submodule. The quantity of voltage sensors is significantly reduced and is free from the number of voltage levels. Furthermore, the voltage balancing control method becomes very simple and the capacitor voltage balance speed is fast. Based on the structure of modular multilevel converter, the DCM2C-STATCOM has the capability of Var compensation and negative-sequence current compensation. The topology characteristics and compensation control method of DCM2C-STATCOM are investigated in this paper. Experimental results obtained from a laboratory prototype validate that the capacitor voltage of the proposed DCM2C-STATCOM can be well balanced and the Var and negative-sequence current compensations are effective.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Analysis and Arm Voltage Control of Isolated Modular Multilevel DC–DC
           Converter with Asymmetric Branch Impedance
    • Authors: Changjiang Sun;Jianwen Zhang;Xu Cai;Gang Shi;
      Pages: 5978 - 5990
      Abstract: Isolated modular multilevel dc-dc converter (IMMDCC), which consists of two modular multilevel converters and a medium-frequency transformer, is attractive for medium-voltage applications because of the following features: the modular structure can handle higher voltage, and synthesizing square-wave voltages toward the alternating current (ac) link increases the dc voltage utilization ratio and achieves the zero-voltage switching operation. However, the asymmetry of arm impedance in practice inevitably leads to power imbalance and divergence of total capacitor voltages in the upper and lower arms of IMMDCC, thereby inducing large ripples in the common-mode arm current and adding a dc bias to the synthesized ac voltage. To compensate for the power imbalance and maintain the stable operation, the interarm phase-shift modulation (IAPSM) scheme and arm voltage-balancing control strategy based on this scheme are presented in this paper. Combining the IAPSM scheme with the intersubmodule phase-shift modulation scheme, deep rising and falling edges of the synthesized square-wave voltage in each phase leg are modified into staircase waveforms with 2N + 1 steps, dv/dt in the ac-link is thus significantly reduced. Simulation and experimental results validate the theoretical analysis and control strategy.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • A Space Vector Pulse Width Modulation for Five-Level Nested Neutral Point
           Piloted Converter
    • Authors: Junjie Li;Jianguo Jiang;Shutong Qiao;
      Pages: 5991 - 6004
      Abstract: This paper introduces a novel five-level nested neutral point piloted (NNPP) converter and analyzes the operating principle of five-level NNPP converter. This paper presents a novel space vector pulse width modulation (SVPWM) algorithm based on gh coordinate for five-level NNPP converter. First, the common-mode voltage is reduced by choosing the appropriate redundant switching states. After that, the floating-capacitor voltage balance control strategy is presented. The appropriate switch combinations of each phase are determined by the control requirements of floating-capacitor voltages respectively and the hardware mapping method of the switching states is presented. Furthermore, the neutral-point voltage balance control strategy is presented. In order to balance the dc-link capacitor voltages, the seven-segment switching sequence is selected according to the control requirements of dc-link capacitor voltages and the neutral-point voltage regulatory factor is introduced to regulate the durations of the redundant switching states in a switching cycle. Finally, the validity of the novel SVPWM algorithm with decoupling control strategies of floating-capacitor voltages and dc-link capacitor voltages is verified by the experimental results of five-level NNPP converter under steady-state and dynamic conditions.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Analysis of Carrier-Based PWM Patterns for a Three-Phase Five-Level
           Bidirectional Buck $+$Boost-Type Rectifier
    • Authors: Lisandra Kittel Ries;Thiago Batista Soeiro;Márcio Silveira Ortmann;Marcelo Lobo Heldwein;
      Pages: 6005 - 6017
      Abstract: This paper analyzes three different carrier-based modulation patterns applied to a three-phase high-power-factor-corrected (PFC) five-level buck+boost-type converter acting as an interface between dc distribution systems and an ac grid. The modulation is analyzed employing the space vectors theory so that the achievable performance is demonstrated. The main advantage of the analyzed modulation strategy is its simplicity, which makes it suitable for digital signal controller (DSC) implementations. This seems straightforward for voltage source converters, but is a challenge for current-multilevel converters that typically employ field-programmable gate array devices to achieve better harmonic distortion performance. This is due to modern power electronics DSCs being typically designed for other converter topologies. The power converter is constructed with two phase-shift-modulated six-switch buck-type PFC converters, paralleled by interphase transformers, and an inverting circuit. The system features: bidirectional current carrying capability; relatively low parts count; high utilization of the semiconductors; and low current and voltage ripple at its terminals. The principle of operation, detailed description, analysis of the modulation strategy, and dimensioning equations for three different power circuit realizations are described in this paper assuming the analyzed modulation patterns. The feasibility of the presented converter is demonstrated by means of a constructed hardware prototype.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • A Modular Multilevel DC–DC Converter Topology With a Wide Range of
           Output Voltage
    • Authors: Qiang Ren;Chi Sun;Fei Xiao;
      Pages: 6018 - 6030
      Abstract: To solve some problems caused by the ac control method used for the existing modular multilevel dc-dc converter (MMDC), this paper has proposed a new MMDC topology with a wide range of output voltage by means of dc control. By reconstructing the submodule structure, the converter has a power branch and an auxiliary balance branch, which are used to transmit dc power and balance the capacitor voltage, respectively. Both dc analysis and control method are adopted to establish a mathematical model so as to deduce the mathematical relationships between the key electrical parameters. Moreover, what have been done include analyzing the self-balancing principle of the capacitor voltage and the mechanism of the auxiliary balance branch, calculating the related parameters of the capacitor voltage fluctuation, and presenting a dc closed-loop control strategy based on a small-signal model. The analyses of the steady and dynamic states in combination with simulation and experiment show that the proposed converter can stably operate in the mode of dc control, with a large adjustable range of output voltage, a small fluctuation in voltage of the capacitor, and the ability of the inductor to suppress the spike of the auxiliary balance current effectively so as to reduce the impact on the device.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Analysis and Comparison of Modular Railway Power Conditioner for
           High-Speed Railway Traction System
    • Authors: Qianming Xu;Fujun Ma;Zhixing He;Yandong Chen;Josep M. Guerrero;An Luo;Yan Li;Yufei Yue;
      Pages: 6031 - 6048
      Abstract: With the rapid development of modern electrified railway, negative-sequence current minimization is one of the most important considerations in the high-speed railway traction system. In the past, many multiple or multilevel topologies with high compensation capacity have been introduced for railway power conditioner (RPC). This paper presents a simplified quantitative comparison of five previous modular RPC topologies for negative sequence compensation in V/V and SCOTT traction systems, aiming for an optimal selection of the compensators. Performance criteria such as transformer requirement, voltage stress and current stress of a power switch, numbers of the power switches and capacitor are derived by analytical methods. Moreover, the numerical comparison of operating controllers is completed for modular RPCs. In addition, power losses of five modular RPCs are obtained by theoretical analysis, IPOSIM calculation as well as PSIM simulation. These calculations are validated via simulations results in PSIM. The main conclusion is that presented modular RPCs can be divided into general purpose RPC and special purpose RPC in terms of the behavior and efficiency. It is helpful to choose the appropriate topology for specific applications.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Reliability Evaluation of Multichip Phase-Leg IGBT Modules Using
           Pressureless Sintering of Nanosilver Paste by Power Cycling Tests
    • Authors: Shancan Fu;Yunhui Mei;Xin Li;Changsheng Ma;Guo-Quan Lu;
      Pages: 6049 - 6058
      Abstract: Nanosilver paste has become a promising lead-free die-attach material for power electronic packaging. This development solves the challenges faced by power device manufacturers to replace the lead-based or lead-free solders for high-temperature applications. This paper proposes the reliability of a 1200-V/150-A multichip insulated-gate bipolar transistor (IGBT) module using pressureless sintering of nanosilver paste as die attachment. The degradation in harsh environment was compared between the proposed IGBT module using pressureless sintered nanosilver and the commercial one using Sn5Pb92.5Ag2.5 solder by power cycling with two different test conditions. The device junction-to-case thermal resistance, I-V characteristics, and switching performance were measured at various numbers of cycles. The results show that the pressureless sintered nanosilver, which was used as the die attachment of the multichip phase-leg IGBT modules, has superior reliability rather than the commercial one.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Multilevel Nonsuperconducting Fault Current Limiter: Analysis and
           Practical Feasibility
    • Authors: Morteza Nazari-Heris;Hesam Nourmohamadi;Mehdi Abapour;Mehran Sabahi;
      Pages: 6059 - 6068
      Abstract: A new topology for nonsuperconducting fault current limiter (NSFCL) based on multilevel switching strategy is proposed in this paper. The proposed multilevel NSFCL circuit aims to control the high-level fault current by inserting different resistances in the circuit. Due to interrupting the fault current based on multilevel switching strategy which results in the decrement of switching numbers, power loss will be reduced and lifetime of the utility devices will be increased. The proposed NSFCL structure has the capability of limiting the fault current based on obtained quantities from current sensors. The proposed NSFCL topology which has no effect on voltage and load currents of the utility, ensures a high level system protection. The analysis of normal and fault conditions of the proposed multilevel NSFCL have been provided and experimental results are demonstrated to prove feasibility of the proposed structure.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Development, Demonstration, and Control of a Testbed for Multiterminal
           HVDC System
    • Authors: Yalong Li;Xiaojie Shi;Bo Liu;Wanjun Lei;Fred Wang;Leon M. Tolbert;
      Pages: 6069 - 6078
      Abstract: This paper presents the development of a scaled four-terminal high-voltage direct current (HVDC) testbed, including hardware structure, communication architecture, and different control schemes. The developed testbed is capable of emulating typical operation scenarios including system start-up, power variation, line contingency, and converter station failure. Some unique scenarios are also developed and demonstrated, such as online control mode transition and station re-commission. In particular, a dc line current control is proposed, through the regulation of a converter station at one terminal. By controlling a dc line current to zero, the transmission line can be opened by using relatively low-cost HVDC disconnects with low current interrupting capability, instead of the more expensive dc circuit breaker. Utilizing the dc line current control, an automatic line current limiting scheme is developed. When a dc line is overloaded, the line current control will be automatically activated to regulate current within the allowable maximum value.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Characterization and Analysis of an Innovative Gate Driver and Power
           Supplies Architecture for HF Power Devices With High dv/dt
    • Authors: Van-Sang Nguyen;Lyubomir Kerachev;Pierre Lefranc;Jean-Christophe Crebier;
      Pages: 6079 - 6090
      Abstract: This paper presents a specific architecture for a low-side/high-side gate driver implementation for power devices running at high switching frequencies and under very high switching speeds. An electromagnetic interference (EMI) optimization is done by modifying the parasitic capacitance of the propagation paths between the power and the control sides, thanks to a specific design of the circuit. Moreover, to reduce the parasitic inductances and to minimize the antenna phenomenon, the paper studies which elements of the drivers' circuitry must be brought as close as possible to the power parts. This is important when the ambient temperature of the power device becomes critical, for instance, in automotive and aeronautic applications. Simulations and experiments validate the advantages of the proposed architecture on the conducted EMI problem.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • An Enhanced Dual Droop Control Scheme for Resilient Active Power Sharing
           Among Paralleled Two-Stage Converters
    • Authors: Hongpeng Liu;Yongheng Yang;Xiongfei Wang;Poh Chiang Loh;Frede Blaabjerg;Wei Wang;Dianguo Xu;
      Pages: 6091 - 6104
      Abstract: Traditional droop-controlled system has assumed that generators can always generate the powers demanded from them. This is true with conventional sources, where fuel supplies are usually planned in advance. For renewable sources, it may also be possible if energy storage is available. Energy storage, usually as batteries, may however be expensive, depending on its planned capacity. Renewable sources are therefore sometimes installed as nondispatchable sources without storage. This may not be viable for remote grids, where renewable sources may be the only or major type of sources. In those cases, traditional droop scheme may not work well when its demanded power cannot be met by some renewable sources due to intermittency. When that happens, the system may become unstable with some sources progressively brought out of generation. To avoid such occurrence, an enhanced dual droop scheme is proposed for general two-stage converters with front rectifiers or dc-dc converters for conditioning powers from renewable sources and rear inverters for channeling powers to remote grids. Unlike the traditional droop scheme, the proposed dual droop scheme uses both dc-link voltage and generated powers for determining the required control actions, which have subsequently been proven stable by small-signal analysis. Experimental results have also verified the effectiveness of the dual droop scheme.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • PV-Module-Integrated AC Inverters (AC Modules) With Subpanel MPP Tracking
    • Authors: David Leuenberger;Jürgen Biela;
      Pages: 6105 - 6118
      Abstract: For small scale roof-top systems, there is a trend towards module-integrated electronics. Module integrated ac inverters (ac modules) connect each photovoltaic (PV) module separately to the single-phase grid. They feature not only increased yield due to module-level maximum power point (MPP) tracking, but also further advantages such as reduced installation cost. This work investigates the concept of subpanel-level MPP tracking for ac modules, which allows us to increase yield thanks to reduced mismatching losses. Topology concepts to realize such a converter are systematically investigated and categorized. A topology comparison identifies two promising system concepts: first a single-stage converter with a three-port power balancer and second a two-stage topology with three paralleled dc-dc converters and a pulse width modulation full bridge. The later features the advantage of a small power-decoupling capacitor and is therefore further investigated. A model-based optimization of the investigated multi-input ac module is performed, applying high performing Gallium Nitride (GaN) devices and nanocrystalline core materials to increase efficiency. The built prototype confirms the accuracy of the model-based optimization. The performed efficiency study reveals an achievable efficiency of ηEU = 94.5%. In order to compete with single-input ac modules, achieving typically an efficiency of 95.5%, the efficiency of multi-input ac modules must improve beyond the level achieved with the investigated two-stage ac-module topology. Given this result, the alternative system concept with a three-port power balancer in combination with a single-stage converter seems to be more promising, as it is conceptually similar to the high efficient single-input ac modules and may achieve the same high efficiency.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Load and Source Battery Simulator Based on Z-Source Rectifier
    • Authors: Seong-Chon Choi;Jung-Hyo Lee;Yong-Su Noh;Do-Yun Kim;Bum-Jun Kim;Chung-Yuen Won;
      Pages: 6119 - 6134
      Abstract: This paper proposes a battery simulator (BS) based on a Z-source rectifier (ZSR), with the intention of emulating the discharge or charge characteristic of an actual lithium-polymer battery with high voltage and large capacity. The proposed BS is used for power testing for battery applications. The battery model, combined with a Shepherd model and a Thevenin model, is adopted to freely change the properties and specifications of the battery and to replicate the dynamic behavior of the battery, which is discretized to utilize the digital controller of the BS. The closed-loop voltage controller at the dc side of the ZSR is designed to emulate the rapid dynamic characteristics of the battery based on small-signal methods, considering the influence of the components of the impedance network. In this paper, battery voltage control algorithm (BVCA) is also utilized to minimize the voltage stress across switches while controlling two dc-side voltages within a wide range of output voltages. Simulation and experimental results are provided to verify the BS of the new feature and the proposed control method.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Decentralized Method for Load Sharing and Power Management in a Hybrid
           Single/Three-Phase-Islanded Microgrid Consisting of Hybrid Source
           PV/Battery Units
    • Authors: Yaser Karimi;Hashem Oraee;Josep M. Guerrero;
      Pages: 6135 - 6144
      Abstract: This paper proposes a new decentralized power management and load sharing method for a photovoltaic (PV)-based, hybrid single/three-phase-islanded microgrid consisting of various PV units, battery units, and hybrid PV/battery units. The proposed method is not limited to the systems with separate PV and battery units, and power flow among different phases is performed automatically through three-phase units. The proposed method takes into account the available PV power and battery conditions of the units to share the load among them. To cover all possible conditions of the microgrid, the operation of each unit is divided into five states in single-phase units and seven states in three-phase units and modified active power-frequency droop functions are used according to operating states. The frequency level is used as trigger for switching between the states. Efficacy of the proposed method in different load, PV generation and battery conditions is validated experimentally in a microgrid lab prototype consisting of one three-phase unit and two single-phase units.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Analysis, Design, and Implementation of an APWM ZVZCS Full-Bridge DC–DC
           Converter for Battery Charging in Electric Vehicles
    • Authors: Venkata Ravi Kishore Kanamarlapudi;Benfei Wang;Ping Lam So;Zhe Wang;
      Pages: 6145 - 6160
      Abstract: An efficient power converter system plays a significant role in the design of battery charging systems for electric vehicles (EVs). In this paper, a new zero-voltage and zero-current switching (ZVZCS) full-bridge dc-dc converter is proposed to reduce the power conversion losses. The proposed converter incorporates a new asymmetrical pulse width modulation (APWM) gating technique for the dc-dc conversion stage in the battery charging system. The proposed dc-dc converter topology achieves zero-voltage switching (ZVS) for all the active switches and near zero-current switching (ZCS) for low-side active switches throughout the charging range of the battery. The proposed APWM technique can reduce the switching and conduction losses compared to the conventional phase-shift modulation (PSM) gating technique. The auxiliary inductance required to ensure ZVS with APWM can also be reduced compared to PSM. Analysis, design, and implementation of the proposed APWM ZVZCS full-bridge dc-dc converter are discussed in this paper. A 100-kHz 1.2-kW laboratory prototype is developed and the experimental results are presented. The results validate the analysis and performance of the proposed converter.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • A Discontinuous Conduction Mode Single-Stage Step-Up Rectifier for
           Low-Voltage Energy Harvesting Applications
    • Authors: Liang Yu;Haoyu Wang;Alireza Khaligh;
      Pages: 6161 - 6169
      Abstract: In this paper, a novel ac/dc converter is proposed for low-voltage and low-power ac rectification applications. The proposed converter manages the energy harvested from microscale electromagnetic generators (MEGs). It integrates the conventional boost and buck-boost topologies with a shared inductor, a bidirectional switch, and two split filtering capacitors. The boost and the buck-boost topologies function in the positive and negative half input cycles, respectively. The inductor is energized by being shorted with the input source through the mosfet channel without using the diodes. This enables active rectification of low-amplitude (below 0.7 V) ac voltages. Theoretical analysis, design considerations, and control method are detailed. A 40-mW circuit prototype, which converts a 0.4-V peak, 100-Hz ac voltage source to 3.3-V dc, is designed and tested to verify the proof of concept.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Zero-Ripple Input-Current High-Step-Up Boost–SEPIC DC–DC Converter
           With Reduced Switch-Voltage Stress
    • Authors: Sin-Woo Lee;Hyun-Lark Do;
      Pages: 6170 - 6177
      Abstract: This paper proposes a zero-ripple input-current high-step-up boost-single ended primary inductor converter (SEPIC) dc-dc converter with reduced switch-voltage stress to overcome some drawbacks of the conventional cascaded boost-SEPIC dc-dc converter. In the proposed converter, the input current ripple is significantly removed by the auxiliary circuit at the boost stage and the voltage gain is more increased by using turn ratio of a coupled inductor at the SEPIC stage. Additional, the switch-voltage stress is reduced due to the clamping circuit, and the reverse-recovery problem of the output diode is alleviated by the leakage inductor. Hence, the low-voltage-rating MOSFET, which has low Rds(on), can be utilized as a main switch device. Therefore, the total power efficiency is improved. The theoretical analysis of the proposed converter is verified on an output 200-V to 200-W prototype.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Autonomous Wideband Piezoelectric Energy Harvesting Utilizing a Resonant
    • Authors: Aaron L. F. Stein;Heath F. Hofmann;
      Pages: 6178 - 6187
      Abstract: Piezoelectric energy harvesters generate electrical power from ambient mechanical vibrations, making these vibrations a viable energy source for powering wireless sensor and identifier nodes. In order to harvest an appreciable amount of power, piezoelectric devices are typically inserted into high-Q mechanical resonant structures that significantly limit their harvesting bandwidth. The dynamic active energy harvesting method has been proposed as a way to widen the bandwidth of resonant piezoelectric energy harvesters; however, an autonomous design has not yet been demonstrated. This paper demonstrates the first autonomous implementation of this method. This was accomplished through the use of a resonant inverter topology in combination with a low-power analog control circuit design that reduces the computational demand of the microcontroller. Experimental results using the Mide Volture V20w piezoelectric device show that the harvested power is up to twice that of the adaptive rectifier method. These results include previously ignored loss mechanisms such as control losses, gating losses, and phase detection losses, making this system the first autonomous energy harvesting system of its kind.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Optimal Inductor Current in Boost DC/DC Converters Regulating the Input
           Voltage Applied to Low-Power Photovoltaic Modules
    • Authors: Ferran Reverter;Manel Gasulla;
      Pages: 6188 - 6196
      Abstract: In energy-harvesting applications, inductor-based switching dc/dc converters are usually employed to regulate the operating voltage of the energy transducer and to transfer the harvested energy to a storage unit. In such a context, this paper analyses the optimal inductor current of the converter that leads to maximum power efficiency. This is evaluated assuming a low-power photovoltaic (PV) module connected to a boost dc/dc converter operating in burst mode so as to reduce the switching losses. The theoretical analysis and the experimental results reported herein prove that this optimal inductor current does not depend on the power generated by the PV module provided that the control circuit is powered from the output, but it does on the output voltage level of the storage unit. Experimental tests with a commercial boost dc/dc converter show that the use of this optimal inductor current provides up to 10% increase in efficiency.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • A Digital Adaptive Driving Scheme for eGaN HEMTs in VHF Converters
    • Authors: Zhi-Liang Zhang;Zhou Dong;Xue-Wen Zou;Xiaoyong Ren;
      Pages: 6197 - 6205
      Abstract: Very-high-frequency (VHF) converters with the conventional driving scheme suffer from serious efficiency drop over entire input voltage range due to gate drive timing mismatch of the eGaN control and synchronous rectification (SR) HEMTs. A digital adaptive driving scheme is proposed to adjust the control and SR gate drive signals efficiently over input voltage range. A state-space model is derived to predict drive timing precisely according to different input voltage and adjust the gate drive signals correspondingly. A high time resolution circuit to improve time resolution by selecting cascaded high-speed buffers is proposed. With the proposed driving scheme, high-frequency switching loss and reverse conduction time of eGaN HEMTs are reduced significantly to maintain high efficiency over entire input voltage range. A 30-MHz VHF SR flyback with the printed circuit board (PCB) fabrication air-core transformer was built. With 18-V input and 5-V/10-W output, the measured efficiency realizes 80.0%. With 24-V input and 5-V/10-W output, the proposed solution improves the efficiency from 72.9% using the conventional driver to 75.1% (an improvement of 2.2%).
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Active Virtual Ground—Bridgeless PFC Topology
    • Authors: Carl Ngai Man Ho;River Tin-ho Li;Ken King-Man Siu;
      Pages: 6206 - 6218
      Abstract: The paper presents a new bridgeless power factor correction (PFC) topology, using a recently proposed controllable LCL filter, namely active virtual ground to achieve efficient power conversion, and high-frequency common mode voltage (CM) reduction. The proposed PFC circuit consists of high-frequency semiconductors for shaping inductor current and low-frequency semiconductors to form two different LCL structures for different conditions. This reduces grid differential mode current ripple or inductance. Besides, the PFC CM voltage, a main problem of bridgeless PFCs, is significantly reduced, since the capacitor in the LCL filter clamps the voltage between the grid and the converter ground. The performance of the proposed PFC is experimentally verified. The results show that the proposed PFC guarantees sinusoidal input current, low high-frequency common-mode voltage noise, and has a good agreement with the theoretical findings.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • A Variable (n/m)X Switched Capacitor DC–DC Converter
    • Authors: Deepak Gunasekaran;Liang Qin;Ujjwal Karki;Yuan Li;Fang Z. Peng;
      Pages: 6219 - 6235
      Abstract: High gain bidirectional dc-dc converter with high efficiency and high power density is a much desired circuit in any converter/inverter system. It is well known that switched capacitor circuits that are variants of the Dickson converter are suitable candidates for such a system. Modular design, absence of external magnetic components, and high efficiency are some of the features that make them suitable candidates. But, the inability to provide fractional and variable voltage gains at high efficiency during normal operation severely limits their application. It also leads to higher voltage stress in the overall system. The aim of this paper is twofold. First, a generalized modular switched capacitor converter, the “(n/m)X converter,” which is a variant of the original Dickson converter is introduced. Using this generalized configuration, the converter can be designed for a required fractional gain. Next, two different methods to enable dynamic variation in gain with high efficiency using the (n/m)X converter are proposed. Detailed analysis, design steps, equivalent circuits, and experimental results for a 1 kW prototype of a variable (4/0.5)X boost converter validate the proposed theory. A peak measured efficiency of over 95% is achieved for the prototype. The design framework and analysis in this paper can be extended to a generic (n/m)X converter.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • A Novel Control Scheme of Three-Phase Single-Switch Quasi-CRM Boost
    • Authors: Kai Yao;Qingsai Meng;Fei Yang;Siwen Yang;
      Pages: 6236 - 6244
      Abstract: A three phase single switch boost rectifier, operating in a quasi-critical conduction mode of the inductor current, can achieve the power factor correction and meet the IEC 61000-3-2. However, the switching frequency is variable in a line cycle, and the design of the inductor and electromagnetic interference filter as well as the power component selection is deteriorated. In this paper, a novel constant frequency control method is proposed for the converter by modulating the on-time of the switch. Compared with the traditional variable frequency control, the proposed control scheme achieves a constant switching frequency in a line cycle, which simplifies the design of the power devices, especially the magnetic components. Furthermore, the switching frequency and the rms value of the inductor current are also reduced, which contributes to a higher efficiency.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Multiobjective Fuzzy-Decision-Making Predictive Torque Control for an
           Induction Motor Drive
    • Authors: Christian A. Rojas;Jose R. Rodriguez;Samir Kouro;Felipe Villarroel;
      Pages: 6245 - 6260
      Abstract: In the recent years, the use of model predictive control in electrical drives has been widely reported both theoretically and experimentally. Predictive torque control has been developed to control induction motor drives, allowing high performance and fast dynamics. However, the optimization used in predictive torque control is based on a single cost function minimization, where control objectives are merged by using weighting factors. The selection of these scalar factors is achieved through offline and online search methods and they are heavily dependent on the system parameters. To avoid this drawback, a multiobjective fuzzy predictive torque control is presented. The proposed strategy replaces the minimization of a scalar cost function with a multiobjective optimization using fuzzy decision making. Experimental implementation is presented to validate the performance of the proposed control scheme.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Reduction of Injection Voltage in Signal Injection Sensorless Drives Using
           a Capacitor-Integrated Inverter
    • Authors: Yong-Cheol Kwon;Seung-Ki Sul;
      Pages: 6261 - 6274
      Abstract: In signal injection sensorless drives, the injection voltage cannot be reduced under a certain value. The lower limit of the injection voltage is mainly enforced by the inverter nonlinearity that causes distortion of the injection voltage and degradation of the position estimation performance. After analyzing the inverter nonlinearity during the voltage injection, it is revealed that parasitic capacitances of insulated-gate bipolar transistors have positive effects on inverter output linearity and sensorless control. Based on this analysis, this paper proposes a method to reduce the injection voltage by connecting additional capacitors to the output terminals of the inverter. Simulation and experimental results are provided to verify the effectiveness of the proposed idea. In the experiments, using the capacitor-integrated inverter, it is shown that the injection voltage can be reduced by more than half without degrading the position estimation performance.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Control Strategy for Multiphase Drives With Minimum Losses in the Full
           Torque Operation Range Under Single Open-Phase Fault
    • Authors: Fernando Baneira;Jesús Doval-Gandoy;Alejandro G. Yepes;Óscar López;Diego Pérez-Estévez;
      Pages: 6275 - 6285
      Abstract: Fault tolerance is an advantageous characteristic of multiphase machines when compared with three-phase ones. During open-phase fault, the current references need to be adapted to provide ripple-free torque. As a consequence of this modification, the postfault phase currents might be larger than the rated current. Such a situation leads to overheating, and to preserve the integrity of the system, some limits are set to the postfault phase currents. Two main strategies have been proposed for the postfault situation: maximum torque (MT) and minimum losses (ML). The MT strategy allows us to obtain the widest torque operation range (TOR) in the postfault situation but does not minimize the stator winding losses; conversely, the ML strategy provides the minimum stator winding losses for each torque value, at the expense of reducing the TOR. Thus, the solutions proposed so far do not achieve minimum stator winding losses in the entire (that of the MT strategy) TOR. This paper presents the full-range minimum losses (FRML) postfault control strategy, which minimizes the losses in the whole TOR, for multiphase machines with sinusoidally distributed windings under single open-phase fault. The FRML strategy is evaluated for different types of machines, phase numbers, and winding arrangements. Experimental results are provided.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • A Novel Flux Estimator Based on Multiple Second-Order Generalized
           Integrators and Frequency-Locked Loop for Induction Motor Drives
    • Authors: Rende Zhao;Zhen Xin;Poh Chiang Loh;Frede Blaabjerg;
      Pages: 6286 - 6296
      Abstract: Accurate flux estimation is essential for the implementation of a high-performance ac motor drive. However, it still faces some problems, which can better be projected by analyzing performances of existing flux estimators, implemented with either a pure integrator or a low-pass filter (LPF). To solve the problems, an alternative flux estimator, implemented with a single second-order generalized integrator (SOGI) and a frequency-locked loop (FLL), is discussed for induction motor drives. The SOGI block included in this algorithm works for integrating the back-electromotive force, which unlike the pure integrator and LPF, does not experience saturation and significant dc offsets caused by different initial conditions. The single-SOGI-FLL estimator does not need additional magnitude and phase compensation, while its performance may deteriorate at low speed, caused by the inverse proportional relationship between its estimated flux and the frequency. A multi-SOGI-FLL flux estimator is, thus, proposed for uncompromised attenuation of dc and harmonic errors even under low-speed condition. Excellent flux estimation can, hence, be offered over the full-speed range, as proven through theoretical studies and experiments.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Generalized Synchronous Optimal Pulse Width Modulation for Multilevel
    • Authors: Jackson Lago;Marcelo Lobo Heldwein;
      Pages: 6297 - 6307
      Abstract: With the growing interest of the industry in high-power medium-voltage multilevel inverters and the technological limitation in high voltage power semiconductors switches, synchronous optimal pulse width modulation techniques, originally developed for two-/three-level inverters, became again a topic of interest, now to optimize multilevel waveforms. This work proposes a novel formulation for the problem of optimizing the modulation pattern of multilevel converters, including in a single optimization problem the decision of the directions for each step transition in addition to the switching angles and, thus, completely defining the optimized multilevel waveform at a given modulation index. In addition, experimental results are presented in order to demonstrate the effectiveness of this optimized modulation technique exemplar applied to a five-level NPC H-bridge feeding a permanent magnet synchronous motor.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Unified Wide-Speed Sensorless Scheme Using Nonlinear Optimization for
           IPMSM Drives
    • Authors: Yingguang Sun;Matthias Preindl;Shahin Sirouspour;Ali Emadi;
      Pages: 6308 - 6322
      Abstract: This paper proposes a novel unified nonlinear optimization-based speed and position estimation algorithm for interior permanent magnet synchronous motor drives at wide speed range operations. A cost function based on the voltage equations in the stationary reference frame is employed for speed and position estimation. The speed and position can be estimated by minimizing the cost function. At low speed, including the standstill condition, the cost function is modified and high-frequency sinusoidal voltage signals are injected in the estimated magnetic axis. A phase locked loop is combined with the proposed position estimator for reducing the noise of estimation results. Compared with existing sensorless methods, a unified estimator is used at low- and high-speed operations and a better performance is obtained in transient and steady-state conditions. The convexity of the cost functions with respect to the speed and position estimation errors is analyzed in the paper. The feasibility of the proposed estimation algorithm is validated with an experimental test bench.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Reliability-Oriented Optimization of the LC Filter in a Buck DC-DC
    • Authors: Yi Liu;Meng Huang;Huai Wang;Xiaoming Zha;Jinwu Gong;Jianjun Sun;
      Pages: 6323 - 6337
      Abstract: Lifetime is an important performance factor in the reliable operation of power converters. However, the state-of-the-art LC filter design of a buck dc-dc converter is limited to the specifications of voltage and current ripples and constrains in power density and cost without reliability considerations. This paper proposes a method to optimize the design of the LC filters from a reliability perspective, besides other considerations. An enhanced model is derived to quantify the lifetime of the capacitor in the filter considering the electrothermal stress on it. Furthermore, the influence of different design aspects such as the value of capacitance, the value of inductance, and the type of the capacitor have been discussed, focusing on their impacts on the key design objectives, which are the cutoff frequency, lifetime, and volume. Based on the analysis, an optimized design is proposed among different parameter sets. A 1-kW converter prototype is applied to verify the theoretical analysis and simulation.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • A Review of Prognostic Techniques for High-Power White LEDs
    • Authors: Bo Sun;Xiaopeng Jiang;Kam-Chuen Yung;Jiajie Fan;Michael G. Pecht;
      Pages: 6338 - 6362
      Abstract: High-power white light-emitting diodes (LEDs) have attracted much attention due to their versatility in a variety of applications and growing demand in markets such as general lighting, automotive lamps, communications devices, and medical devices. In particular, the need for high reliability and long lifetime poses new challenges for the research and development, production, and application of LED lighting. Accurate and effective prediction of the lifetime or reliability of LED lighting has emerged as one of the key issues in the solid-state lighting field. Prognostic is an engineering technology that predicts the future reliability or determines the remaining useful lifetime of a product by assessing the extent of deviation or degradation of a product from its expected normal operating conditions. Prognostics bring benefits to both LED developers and users, such as optimizing system design, shortening qualification test times, enabling condition-based maintenance for LED-based systems, and providing information for return-on-investment analysis. This paper provides an overview of the prognostic methods and models that have been applied to both LED devices and LED systems, especially for use in long-term operational conditions. These methods include statistical regression, static Bayesian network, Kalman filtering, particle filtering, artificial neural network, and physics-based methods. The general concepts and main features of these methods, the advantages and disadvantages of applying these methods, as well as LED application case studies, are discussed. The fundamental issues of prognostics and photoelectrothermal theory for LED systems are also discussed for clear understanding of the reliability and lifetime concepts for LEDs. Finally, the challenges and opportunities in developing effective prognostic techniques are addressed.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Energy Density Enhancement of Stacked Switched Capacitor Energy Buffers
           Through Capacitance Ratio Optimization
    • Authors: Yu Ni;Saad Pervaiz;Minjie Chen;Khurram K. Afridi;
      Pages: 6363 - 6380
      Abstract: The recently proposed stacked switched capacitor (SSC) energy buffer architecture can extend the lifetime of single-phase ac-dc converters by replacing the electrolytic capacitors needed for twice-line-frequency energy storage with film or ceramic capacitors, while maintaining comparable effective energy density. This paper presents a methodology for further increasing the effective energy density of SSC energy buffers by optimizing the capacitance ratios of the capacitors used in the energy buffer. It is systematically shown that the relative enhancement in effective energy density depends on the required ripple ratio and the number of backbone and supporting capacitors in the energy buffer. The proposed approach can substantially increase the effective energy density of the energy buffer. For example, the effective energy density of a 1-10 enhanced unipolar SSC energy buffer, designed for a 10% ripple ratio, can be increased by 100% as a result of this capacitance ratio optimization. The presented methodology is validated using a 1-2 enhanced unipolar SSC energy buffer designed for an 8-W offline LED driver.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Theoretical and Experimental Study of 22 kV SiC Emitter Turn-OFF (ETO)
    • Authors: Xiaoqing Song;Alex Q. Huang;Meng-Chia Lee;Chang Peng;
      Pages: 6381 - 6393
      Abstract: Controllable three terminal high voltage (>10 kV) power switches based on silicon carbide (SiC) material are gaining significant attentions since silicon (Si) power switches such as insulated gate bipolar transistors (IGBTs) are typically designed for much lower blocking voltages. After more than 30 years of commercial development, there is a fundamental limitation in designing Si IGBTs with more than 6.5 kV voltage rating. On the other hand, the voltage barrier for SiC power devices could easily exceed 10 kV. In this paper, a world record 22 kV SiC p-type emitter turn-OFF (ETO) (p-ETO) thyristor is reported and analyzed as a promising candidate for high-voltage applications, such as solid-state circuit breaker, HVdc, flexible alternating current transmission system (FACTS), and motor drives. The device is based on a 2 cm2 22 kV p-type SiC gate turn-OFF thyristor (p-GTO) structure. Its static performances are analyzed exhibiting a high voltage (22 kV) blocking characteristic, ultralow leakage current, and a low forward voltage drop (~7 V at 100 A) for a broad range of temperatures. The dynamic performances including turn-ON and turn-OFF are studied. Key switching characteristics such as turn-OFF storage time, turn-OFF loss, dv/dt, and di/dt are presented and analyzed. In addition, the large reverse biased safe operation area (RBSOA) of the 22 kV SiC ETO is theoretically analyzed and verified by simulations and experimental tests.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Analytical and Experimental Investigation on A Dynamic Thermo-Sensitive
           Electrical Parameter With Maximum $dI_{C}/dt$ During Turn-off for High
           Power Trench Gate/Field-Stop IGBT Modules
    • Authors: Yuxiang Chen;Haoze Luo;Wuhua Li;Xiangning He;Francesco Iannuzzo;Frede Blaabjerg;
      Pages: 6394 - 6404
      Abstract: In this paper, a dynamic thermo-sensitive electrical parameter (DTSEP) for extracting the junction temperature of the trench gate/field-stop insulated gate bipolar transistor (IGBT) modules by using the maximum collector current falling rate is proposed. First, a theoretical model of the transient collector current during turn-off process is developed in terms of the behavior characteristics of the inside storage carriers. Then, the inherent linear relationship between the maximum collector current falling rate dIC/dt and junction temperature Tj is demonstrated and investigated. Fortunately, benefitting from the presence of the intrinsic parasitic inductance LeE between the Kelvin and power emitters of IGBT modules, the maximum dIC/dt can be easily measured to validate the theoretical analysis. Consequently, the maximum dIC/dt during turn-off process is a promising DTSEP for IGBT module junction temperature estimation. Moreover, the physical device parameters that affect the temperature sensitivity of the maximum dIC/dt are also discussed with the derived transient collector current falling model.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Single-Pulse Avalanche Mode Robustness of Commercial 1200 V/80 mΩ
           SiC MOSFETs
    • Authors: Mitchell D. Kelley;Bejoy N. Pushpakaran;Stephen B. Bayne;
      Pages: 6405 - 6415
      Abstract: Commercialization of 1200-V silicon carbide (SiC) MOSFET has enabled power electronic design with improved efficiency as well as increased power density. High-voltage spikes induced in applications such as solenoid control, solid-state transformer, boost converter, and flyback converter can drive the MOSFET into avalanche mode operation due to high di/dt coupled with parasitic inductance. Avalanche mode operation is characterized by high-power dissipation within the device due to the high voltage and current crossover. This study focuses on the evaluation of two commercially available SiC MOSFETs from different manufacturers, each rated for 1200 V with an ON-state resistance of 80 mΩ, during unclamped inductive switching (UIS) mode operation. To determine device reliability, a decoupled UIS testbed was developed to evaluate the avalanche energy robustness at 22 °C and 125 °C during two specific conditions: high current and low energy, and low current and high energy. The SiC MOSFETs were evaluated using a load inductance of 1.42, 5.1, 10.5, and 15.8 mH to understand the effect of current and avalanche energy on device failure. To correlate the experimental results with the failure mechanism, estimated junction temperature and static device characteristics are presented; additionally, MOSFETs were decapsulated to examine the failure sites on the semiconductor die.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • An Analytical Model for False Turn-On Evaluation of High-Voltage
           Enhancement-Mode GaN Transistor in Bridge-Leg Configuration
    • Authors: Ruiliang Xie;Hanxing Wang;Gaofei Tang;Xu Yang;Kevin J. Chen;
      Pages: 6416 - 6433
      Abstract: Compared with the state-of-the-art Si-based power devices, enhancement-mode Gallium Nitride (E-mode GaN) transistors have better figures of merit and exhibit great potential in enabling higher switching frequency, higher efficiency, and higher power density for power converters. The bridge-leg configuration circuit, consisting of a controlling switch and a synchronous switch, is a critical component in many power converters. However, owing to the low threshold voltage and fast switching speed, E-mode GaN devices are more prone to false turn-on phenomenon in bridge-leg configuration, leading to undesirable results, such as higher switching loss, circuit oscillation, and shoot through. In order to expand gate terminal's safe operating margin without increasing reverse conduction loss during deadtime, negative gate voltage bias for turn-off and antiparallel diode could be applied to E-mode GaN device. In this paper, with consideration of strong nonlinearities in C-V and I-V characteristics of high-voltage (650 V) E-mode GaN transistors, analytical device models are first developed. Then, we develop an analytical circuit model that combines the circuit parameters with intrinsic characteristics of the high-voltage GaN transistor and antiparallel diode. Thus, key transient waveforms with regard to the false turn-on problem can be acquired, including displacement current and false triggering voltage pulse on gate terminal. The simulated waveforms are then verified on a testing board with GaN-based bridge-leg circuit. In contrast to piecewise switching process models and PSpice simulation, the proposed model exhibits outstanding performances. To provide design guidelines for mitigating false turn-on of GaN transistor, the impacts of different circuit parameters, along with the optimum negative gate voltage bias, are investigated based on the proposed model.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Study on Effect of Junction Temperature Swing Duration on Lifetime of
           Transfer Molded Power IGBT Modules
    • Authors: Ui-Min Choi;Frede Blaabjerg;Søren Jørgensen;
      Pages: 6434 - 6443
      Abstract: In this paper, the effect of junction temperature swing duration on lifetime of transfer molded power insulated gate bipolar transistor (IGBT) modules is studied and a relevant lifetime factor is modeled. This study is based on 39 accelerated power cycling test results under six different conditions by an advanced power cycling test setup, which allows tested modules to be operated under more realistic electrical conditions during the power cycling test. The analysis of the test results and the temperature swing duration dependent lifetime factor under different definitions and confidence levels are presented. This study enables to include the t△T⌋ effect on lifetime model of IGBT modules for its lifetime estimation and it may result in improved lifetime prediction of IGBT modules under given mission profiles of converters. A postfailure analysis of the tested IGBT modules is also performed.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Fault Diagnosis of High-Resistance Connection in a Nine-Phase
           Flux-Switching Permanent-Magnet Machine Considering the Neutral-Point
           Connection Model
    • Authors: Jun Hang;Jianzhong Zhang;Shichuan Ding;Ming Cheng;
      Pages: 6444 - 6454
      Abstract: This paper presents a fault diagnosis technique for high-resistance connection (HRC) in a nine-phase flux-switching permanent-magnet (FSPM) machine based on zero-sequence voltage components (ZSVC), where the neutral-point connection mode is considered. A nine-phase FSPM machine topology is first introduced and no-load back electromotive force waveforms are analyzed. Moreover, the topologies of the nine-phase FSPM drive with different neutral-point connection modes are studied. Then, the mathematical model of a nine-phase FSPM machine with HRC is established with the consideration of the neutral-point connection mode and then the influence of the HRC on the ZSVC is analyzed based on the established model. It is shown that the HRC may be diagnosed by monitoring the change of the spectral contents of the ZSVC. Furthermore, this paper focuses on the situation of the nine-phase FSPM machine with one neutral point. In this case, to remove the influence of the FSPM machine operating point, an effective fault indicator is defined and used for HRC fault detection. Finally, the simulation and the experiment are carried out to validate the proposed method. Both the results show that the proposed method can be applied for the HRC fault diagnosis in a nine-phase FSPM machine.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Fault-Tolerant and Reliable Structure for a Cascaded Quasi-Z-Source
           DC–DC Converter
    • Authors: Mohammad Mehdi Haji-Esmaeili;Mersad Naseri;Hossein Khoun-Jahan;Mehdi Abapour;
      Pages: 6455 - 6467
      Abstract: This paper proposes a fault-tolerant-cascaded quasi-Z-source dc-dc converter structure and investigates its reliability through a precise mathematical evaluation. In order to enhance the reliability of the suggested topology, a robust control method is considered, as well. According to the utilized control method, at the moment of fault occurrence, the defected modules are isolated from the converter by the virtue of some considered relays allowing the whole system keep working with the remained modules. Since the defected modules are eliminated from the circuit, the duty cycles of the switches will be changed through the controlling system, so that the remained modules take the responsibility of maintaining the output voltage in the desired level. Operation principle of the converter along with the control method (consists of fault detection and elimination systems) is provided. Additionally, a reliability evaluation technique is considered and, reliability comparison between the proposed, conventional and flyback structures is illustrated. Taking advantage of a laboratory-built prototype, the practicality of the suggested structure is proven. The obtained results confirm higher reliability and mean time to failure of the proposed converter compared to the conventional and flyback structures. Therefore, it could be counted as a suitable structure in sensitive industrial applications.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Iterative Learning Controller With Multiple Phase-Lead Compensation for
           Dual-Mode Flyback Inverter
    • Authors: Hyosin Kim;Jin S. Lee;Jih-Sheng Lai;Minsung Kim;
      Pages: 6468 - 6480
      Abstract: This paper proposes an iterative learning control (ILC) scheme for a dual-mode flyback inverter operating in both discontinuous conduction mode (DCM) and continuous conduction mode (CCM). In dealing with more than 200-W power applications, the dual-mode flyback inverter takes advantage of both DCM and CCM operations. However, it is difficult to control the output current because the system gain is quite low in DCM and the system transfer function has a right-half plane zero in CCM. To overcome the problems occurring in DCM and CCM operations, we propose an ILC scheme with multiple phase-lead compensation. The ILC is proposed to achieve accurate reference tracking and to reject periodic disturbances. The multiple phase-lead compensation technique is then employed to compensate for the effect of different system dynamics. As a theoretical result, we derive the asymptotic stability of the closed-loop system. We also performed the numerical simulations and experimental tests to validate the proposed control approach.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Control of a Three-Phase Boost PFC Converter Using a Single DC-Link
           Voltage Sensor
    • Authors: Ayan Mallik;Alireza Khaligh;
      Pages: 6481 - 6492
      Abstract: This paper proposes a new methodology to control a three-phase boost power factor correction (PFC) using a single dc output voltage sensor. Typically, a PFC control technique requires measurement from five independent sensors, i.e., two input voltages, one output dc voltage, and two input phase currents. Elimination of four sensors in the control system of a PFC converter is theoretically feasible and implementable without compromising stability and power quality of the converter, as analyzed and presented in this paper. The proposed control technique uses the ripple information of the measured dc-link voltage, converter dynamics, and switching states at a preceding sample in order to estimate the present state of four other unknown state variables and, thus, establishes the control method. A 2.2-kW experimental prototype of a three-phase boost PFC is developed and tested to verify the accuracy and applicability of the proposed control logic at different line and load conditions. According to the experimental measurements, conversion efficiency more than 98%, total harmonic distortion as low as 4.3%, and an output voltage ripple of ±2% are achieved at 2.2-kW output power.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Generalized Minimum Common-Mode Voltage PWM for Two-Level Multiphase VSIs
           Considering Reference Order
    • Authors: Keng-Yuan Chen;Meng-Sheng Hsieh;
      Pages: 6493 - 6509
      Abstract: A minimum common-mode voltage (CMV) pulse-width modulator (MCMV_PWM) is proposed for generalized two-level N -phase voltage-source inverters (VSIs) with odd phase numbers. The CMV engenders the breakdown of winding insulation, electromagnetic interference, and leakage currents. Recently, many CMV reduction/elimination PWMs have been widely discussed, but those discussions have mainly focused on the topologies of multilevel inverters or dual-inverter drives for open-ended windings. Therefore, in this study, a two-level multiphase VSI that can be applied to multiphase motor drives, in general, is considered. The relation between switching states and the CMV is derived first. Subsequently, the CMV is minimized using two different leg distributions: double-sided and central distributions. Consequently, for an N-phase VSI, the proposed method reduces the maximum CMV to Vdc/(2N); that CMV is lower than the maximum CMV of the conventional space-vector PWM (SVPWM), namely Vdc/2. In experiments, five-phase and seven-phase VSIs were constructed. The waveforms of the CMV, phase voltage, and phase current produced by the SVPWM and the proposed MCMV_PWM confirm the practicality of CMV minimization.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Plug-In Repetitive Control Strategy for High-Order Wide-Output Range
           Impedance-Source Converters
    • Authors: Yachao Wang;Ahmed Darwish;Derrick Holliday;Barry W. Williams;
      Pages: 6510 - 6522
      Abstract: High-order wide-output (HOWO) impedance-source converters (ISCs) have been presented for ac inverter applications that require voltage step-up ability. With intrinsic passive impedance networks as energy sources, these converters are able to achieve voltage boosting with either polarity, leading to improved dc-link voltage utilization compared with the conventional two-level converter. However, HOWO-ISCs suffer from transfer functions giving low bandwidth, a penalty of increased passive devices and right-half-plane zeros, which result in lower order distortion of the ac output power. In this paper, a modified plug-in repetitive control scheme is presented for HOWO-ISCs with accurate reference tracking (hence low distortion), fast dynamic response, and enhanced robustness. By using zero-phase-shift finite impulse response filters in both the internal model of the repetitive controller and its compensation network, the proposed method achieves zero steady-state error and an extended closed-loop bandwidth. For HOWO-ISC cases, this method outperforms conventional proportional-integral (PI) control, which has considerable steady-state error. It also eliminates the need of parallel loops for several frequencies when proportional resonant control or orthogonal transformation-based PI schemes are used to remove lower order distortion. The design process and performance analysis of the proposed repetitive control strategy are based on a novel three-phase HOWO-ISC configuration with a reduced number of switches. Simulation and experimental results confirm the feasibility and effectiveness of the proposed control approach.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Variable-Switching-Frequency State-Feedback Control of a Phase-Shifted
           Full-Bridge DC/DC Converter
    • Authors: Ayan Mallik;Alireza Khaligh;
      Pages: 6523 - 6531
      Abstract: This paper presents a methodology to control a phase-shifted full-bridge (PSFB) dc/dc converter with variable switching frequency, as a function of the output load power. The main objective of such control is to maximize the conversion efficiency at a wide range of load power levels. By tuning the switching frequency, the net phase of the input impedance of the converter can be manipulated, and thus, at the lower load power operation, the net input impedance can be made highly inductive to achieve zero-voltage switching (ZVS) at the primary-side switches. This paper proposes an efficiency maximization method, which derives an optimum switching frequency based on the load power from a loss-minimization model. In addition, a state-feedback-based control method is proposed for maintaining a tight dynamic regulation over the converter output under a load transient. A 6-kW laboratory prototype of the PSFB converter is developed and designed to validate the proposed control algorithm. The experimental results show a conversion efficiency of 98% at full load and output voltage ripple of ±1%, while ensuring ZVS at all operating points between 100 W and 6 kW.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Dynamic Performance Improvement of Diode–capacitor-Based High Step-up
           DC–DC Converter Through Right-Half-Plane Zero Elimination
    • Authors: Yan Zhang;Jinjun Liu;Zhuo Dong;Hongliang Wang;Yan-Fei Liu;
      Pages: 6532 - 6543
      Abstract: Diode-capacitor-based dc-dc converters provide a simple and low cost solution for high step-up voltage regulation in solar and fuel cell generation. Transient modeling analysis reveals their worse influence of nonlinear and nonminimum-phase system characteristic due to right-half-plane (RHP) zero, especially in high voltage gain application. However, the process of energy transfer for diode-capacitor-based dc-dc converter is different from basic dc-dc converter. Based on the unique feature, this paper proposes an improved main circuit structure with parallel connection of resistive-capacitive damping network across the intermediate capacitor to achieve good dynamic performance. By optimal parameter design according to Routh-Hurtwitz criterion, all the RHP zeros in the transfer function of control-to-output voltage are eliminated completely. Then, by the case of diode-capacitor-based boost converter, the adaptive PI controller is designed to deal with nonlinear characteristic of voltage gain. It gets good dynamic performance under wide range output voltage. All the theoretical findings and design approaches are verified by simulation and experiment results. The existing diode-capacitor-based high step-up dc-dc converters with slight main circuit modification are more promising in renewable energy application.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • A PV Micro-inverter With PV Current Decoupling Strategy
    • Authors: Chien-Yao Liao;Wen-Shiun Lin;Yaow-Ming Chen;Cheng-Yen Chou;
      Pages: 6544 - 6557
      Abstract: The objective of this paper is to propose a novel photovoltaic (PV) micro-inverter with PV current decoupling (PVCD) strategy to achieve maximum power point tracking (MPPT) performance without using large electrolytic capacitors. Conventionally, the grid-connected PV micro-inverter needs a large PV-side electrolytic capacitor to suppress the double-line frequency voltage ripple, which is caused by the injected ac grid power, to achieve the desired MPPT performance. However, the short lifetime electrolytic capacitor will reduce the PV micro-inverter's reliability dramatically. Therefore, different active power decoupling circuits (APDCs) have been proposed in published papers to reduce the required input capacitance so that the long lifetime film capacitor can be used to replace the electrolytic capacitor. Unlike the conventional APDC with charging and discharging modes operation, a novel PVCD strategy, which is based on the concept of current decoupling instead of power decoupling, is proposed to simplify the control mechanism of the PV micro-inverter. Furthermore, to accomplish the proposed current decoupling concept, a novel circuit topology for the PV micro-inverter is also proposed. With the proposed PVCD strategy, the current decoupling tank (CDT) inside the proposed PV micro-inverter can buffer the current difference between the constant current from the PV panel and the rectified sinusoidal current of the ac grid current. Therefore, the input capacitance on the PV-side can be reduced dramatically and the long lifetime film capacitor can be used to replace the electrolytic capacitor. The reliability of the PV micro-inverter with good MPPT performance can be increased. In this paper, the operation principle and the component design of the proposed PV micro-inverter with PVCD strategy will be presented. Simulation results and experimental results of a prototype 240 W PV micro-inverter is shown to verify the performance of the PV micro-inverter with PVCD strate-y.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Model Predictive Switching Pattern Control for Current-Source Converters
           With Space-Vector-Based Selective Harmonic Elimination
    • Authors: Hang Gao;Bin Wu;Dewei Xu;Ricardo P. Aguilera;Pablo Acuna;
      Pages: 6558 - 6569
      Abstract: This paper presents a model predictive switching pattern control (MPSPC) for a current-source converter (CSC), which achieves superb low-order harmonics elimination performance in steady state and improved transient responses. Based on a proposed space-vector-based selective harmonic elimination (SHE) method and prediction of load current at the next sampling instant, MPSPC prefers to following a precalculated SHE-pulse width modulation (PWM) pattern in steady state, and governing the CSC through a model predictive control (MPC) approach during transients. In comparison with existing schemes, the advantages of MPSPC are threefold: First, quantization error, introduced by a constant sampling frequency in MPC and degrading steady-state low-order harmonic elimination, is mitigated in the proposed scheme. Second, there is no weighting factor in the cost function, as used in existing schemes. Finally, MPSPC is totally realized based on one-step prediction, which simplifies the structure of the scheme. Both simulation and experimental results verify the steady state and dynamic performance of MPSPC with different SHE-PWM patterns.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Three-Phase VSI Optimal Switching Loss Reduction Using Variable Switching
    • Authors: Oier Oñederra;Iñigo Kortabarria;Iñigo Martínez de Alegría;Jon Andreu;José Ignacio Gárate;
      Pages: 6570 - 6576
      Abstract: Loss reduction in converters is one of main targets in power electronics to obtain higher efficiency and lower thermal stress, which can enhance the lifetime of devices. This paper presents a variable switching frequency technique for switching loss reduction in a three-phase voltage source inverter, obtaining similar output current quality as that of a space vector pulse width modulation (SVPWM) algorithm. This type of optimization has not been applied for a three-phase system before. Simulation and experimental results are also shown. The output current ripple rms value of three-phase SVPWM is used as the optimization constraint. Results of the optimization of the switching losses with quality constraints in the switching frequency as the variable are presented for different load angles and compared with classical SVPWM. Experimental results show that this technique can save up to nearly 19% in switching losses with similar total harmonic distortion of the output current, concluding that converter losses are reduced without reducing output current quality.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Assessment and Performance Comparison of Positive Feedback Islanding
           Detection Methods in DC Distribution Systems
    • Authors: Ahmed M. I. Mohamad;Yasser Abdel-Rady I. Mohamed;
      Pages: 6577 - 6594
      Abstract: Due to the high penetration level of dc-based distributed generators (DGs) and dc loads, dc distribution systems are gaining widespread acceptance in modern power grids. Therefore, dc distribution systems are expected to operate parallel to the existing ac ones. However, the techniques of islanding detection in dc grids have not been fully studied in the current literature. This paper presents a detailed analysis, performance comparison, and design guidelines of four different positive feedback islanding detection methods in dc distribution systems. In each method, the range of control parameters that guarantee system stability is analytically obtained. The effects of system parameters, such as the dc system resistance and inductance, DG filter capacitance, and local load resistance, on each islanding detection method, are thoroughly addressed. Furthermore, the interactions between DGs connected at different locations of the distribution feeder and equipped with positive feedback islanding detection methods are studied and characterized. Detailed time-domain nonlinear simulations and experimental results validate the analytical results.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Repetitive Controller for VSIs in Droop-Based AC-Microgrid
    • Authors: Ashutosh Trivedi;Mukhtiar Singh;
      Pages: 6595 - 6604
      Abstract: A major requirement of ac-microgrid is to keep on feeding its connected load at regulated voltage and frequency, which is difficult to achieve especially in inverter-based microgrid. In modern distribution system, most of the loads are nonlinear in nature and draw harmonic current. The variable load with the nonlinear characteristics may distort the output voltage and degrade the power quality. In order to mitigate the negative impact of these disturbances on the output voltage, a novel repetitive controller (RC) has been proposed. A mixed-sensitivity-based approach is used here to design the RC and the comparison of performance with nonlinear load is shown with a conventional proportional plus integral regulator. The overall microgrid system is designed and simulated with the help of various toolboxes available in MATLAB/SIMULINK. Furthermore, a scaled hardware prototype of microgrid consisting of two voltage source inverter is developed and controlled using RC in real time with the help of field programmable gate array (FPGA).
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Fixed Switching Frequency Generalized Peak Current Control (GPCC) of
           DC–AC Converters
    • Authors: Mohammad Ebrahimi;S. Ali Khajehoddin;
      Pages: 6605 - 6616
      Abstract: A fast and robust fixed switching frequency peak current controller for DC-AC converters is presented. The proposed method tends to mimic the switching behavior of pulse width modulation (PWM) techniques, so it features all the advantages of peak current controllers (such as simplicity, fast transient, and optimum dynamic response), with the superiority of fixed switching frequency and harmonic free output. The proposed method is a generalized approach that can be applied to different PWM schemes. The method is specifically elaborated for single-phase distributed generation applications, using various inverter topologies and mimicking different PWM schemes. Moreover, adaptive bands are proposed to provide active damping for the controller, to extend use of the proposed method for inverters with LCL output filters. Feasibility and performance of the controller is shown by means of simulations and experiments.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • The Recognition and Control of Nonideal Soft-Switching Frequency for
           Wireless Power Transfer System Based on Waveform Identification
    • Authors: Yue Sun;Huan Zhang;Aiguo Patrick Hu;Chun-Sen Tang;Li-Juan Xiang;
      Pages: 6617 - 6627
      Abstract: Nonideal frequency problems can occur in a wireless power transfer system due to multiple soft-switching frequencies and frequency bifurcation. To make the system work at an ideal frequency with high-power transfer capability and efficiency, a method based on waveform identification is proposed. First, the space state model of a SP type WPT system is built, and the waveforms at ideal and nonideal working frequencies are obtained based on the stroboscopic mapping theory. Second, according to the characteristics of these waveforms, the swing door algorithm is improved by waveform distortion rate and fast Fourier transformation, which is used to recognize nonideal waveforms. Then, a control strategy based on “online self-determined optimization” is proposed to deal with the problem. Finally, the results of simulation and experiments show that the method proposed in this paper can identify the waveforms at nonideal frequency and find an ideal working frequency for the WPT system.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Energy Balancing Improvement of Modular Multilevel Converters Under
           Unbalanced Grid Conditions
    • Authors: Andres E. Leon;Santiago J. Amodeo;
      Pages: 6628 - 6637
      Abstract: This paper presents a feedback/feed-forward control strategy to improve the voltage balancing of modular multilevel converters (MMCs) under unbalanced grid conditions. The inclusion of a feed-forward compensation improves the disturbance rejection capability against asymmetrical faults and sudden voltage imbalances in the ac grid. The floating capacitor voltages of the MMC are controlled in two stages. The first one equally distributes the voltages in each arm, and the second one balances the energy among the six arms. This last control stage is also divided into the called horizontal and vertical balancing. Based on a detailed analysis of the power terms disturbing the MMC arm energies, the control strategy is tailored to improve the voltage transient response by adding feed-forward terms to both horizontal and vertical balancing controls. In addition, various approaches to manage the MMC under unbalanced grid conditions are compared regarding several aspects, such as capacitor voltage ripple, balancing performance, and negative-sequence current injection. Advantages and disadvantages of both the proposed and the conventional energy-based control schemes are also studied, showing that the voltage control performance can be improved by enhancing the existing MMC control systems.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Active Output-Voltage-Sharing Control Scheme for Input Series Output
           Series Connected DC–DC Converters Based on a Master Slave Structure
    • Authors: Lu Qu;Donglai Zhang;Zhiyun Bao;
      Pages: 6638 - 6651
      Abstract: DC/DC converters connected in series or parallel allow low power devices to be used in high power conversions. The input series output series (ISOS) connection is suitable for situations where both the input and output sides are high voltage fields. To ensure that each module shares voltage with the other, this paper proposes an active output voltage sharing (AOVS) control scheme. The scheme introduces sharing control in the output side so that the isolation is not needed between the input and output sides in the control loop. The AOVS control scheme, consisting of a common output voltage loop and individual output voltage sharing loop, has a master-slave structure. To improve the reliability and realize a hot-plug, this paper also provides an automatic master-slave form of the AVOS control scheme. A simulation of the frequency and time domains is used to verify the accuracy of the small signal model, and an ISOS-connected prototype consisting of three forward converters is made to test the steady and dynamic characteristics of the proposed scheme.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
  • Enhanced Instantaneous Power Theory for Control of Grid Connected Voltage
           Sourced Converters Under Unbalanced Conditions
    • Authors: Allan A. Montanari;Aniruddha M. Gole;
      Pages: 6652 - 6660
      Abstract: Undesirable power oscillations take place in grid-connected voltage sourced converters (VSC) during unbalanced conditions. This problem becomes more difficult and pronounced during transients which include zero sequence content flowing through the ac/dc interface. This paper introduces a method especially designed to control the instantaneous power in voltage sourced converters operating under unbalanced transient scenarios with positive, negative, and zero sequence content. The control is based on an adaptive transformation that instantaneously adjusts itself to the dynamic voltage conditions. The method allows control over constant and oscillating terms of the instantaneous three-phase power. It is applied to grounded three-wire and four-wire schemes, especially accommodating zero sequence unlike previous approaches. The technique expands the application of the p-q theory, which is attached to the αβ0 transformation. The effectiveness of the proposed control approach and the proposed power conditioning scheme was demonstrated using electromagnetic transient simulation of a VSC connected to an ac system.
      PubDate: Aug. 2017
      Issue No: Vol. 32, No. 8 (2017)
School of Mathematical and Computer Sciences
Heriot-Watt University
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