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  Subjects -> ELECTRONICS (Total: 155 journals)
Showing 1 - 200 of 277 Journals sorted alphabetically
Advances in Biosensors and Bioelectronics     Open Access   (Followers: 4)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 7)
Advances in Microelectronic Engineering     Open Access   (Followers: 9)
Advances in Power Electronics     Open Access   (Followers: 17)
Aerospace and Electronic Systems, IEEE Transactions on     Hybrid Journal   (Followers: 175)
American Journal of Electrical and Electronic Engineering     Open Access   (Followers: 19)
Annals of Telecommunications     Hybrid Journal   (Followers: 7)
Archives of Electrical Engineering     Open Access   (Followers: 11)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 7)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 25)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 16)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 30)
Biomedical Instrumentation & Technology     Hybrid Journal   (Followers: 6)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 9)
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: 38)
China Communications     Full-text available via subscription   (Followers: 7)
Circuits and Systems     Open Access   (Followers: 12)
Consumer Electronics Times     Open Access   (Followers: 6)
Control Systems     Hybrid Journal   (Followers: 86)
Edu Elektrika Journal     Open Access  
Electronic Design     Partially Free   (Followers: 68)
Electronic Markets     Hybrid Journal   (Followers: 7)
Electronic Materials Letters     Hybrid Journal   (Followers: 1)
Electronics     Open Access   (Followers: 50)
Electronics and Communications in Japan     Hybrid Journal   (Followers: 8)
Electronics For You     Partially Free   (Followers: 54)
Electronics Letters     Hybrid Journal   (Followers: 23)
Embedded Systems Letters, IEEE     Hybrid Journal   (Followers: 38)
Energy Harvesting and Systems : Materials, Mechanisms, Circuits and Storage     Hybrid Journal   (Followers: 2)
Energy Storage Materials     Full-text available via subscription  
EPJ Quantum Technology     Open Access  
EURASIP Journal on Embedded Systems     Open Access   (Followers: 12)
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)
Giroskopiya i Navigatsiya     Open Access  
Haptics, IEEE Transactions on     Hybrid Journal   (Followers: 3)
IEEE Antennas and Propagation Magazine     Hybrid Journal   (Followers: 45)
IEEE Antennas and Wireless Propagation Letters     Hybrid Journal   (Followers: 37)
IEEE Journal of Emerging and Selected Topics in Power Electronics     Hybrid Journal   (Followers: 26)
IEEE Journal of the Electron Devices Society     Open Access   (Followers: 7)
IEEE Journal on Exploratory Solid-State Computational Devices and Circuits     Hybrid Journal   (Followers: 1)
IEEE Power Electronics Magazine     Full-text available via subscription   (Followers: 41)
IEEE Transactions on Antennas and Propagation     Full-text available via subscription   (Followers: 36)
IEEE Transactions on Automatic Control     Hybrid Journal   (Followers: 45)
IEEE Transactions on Circuits and Systems for Video Technology     Hybrid Journal   (Followers: 13)
IEEE Transactions on Consumer Electronics     Hybrid Journal   (Followers: 27)
IEEE Transactions on Electron Devices     Hybrid Journal   (Followers: 11)
IEEE Transactions on Information Theory     Hybrid Journal   (Followers: 18)
IEEE Transactions on Power Electronics     Hybrid Journal   (Followers: 47)
IEEE Transactions on Signal and Information Processing over Networks     Full-text available via subscription   (Followers: 5)
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: 12)
IET Power Electronics     Hybrid Journal   (Followers: 23)
IET Wireless Sensor Systems     Hybrid Journal   (Followers: 15)
IETE Journal of Education     Open Access   (Followers: 3)
IETE Journal of Research     Open Access   (Followers: 8)
IETE Technical Review     Open Access   (Followers: 7)
Industrial Electronics, IEEE Transactions on     Hybrid Journal   (Followers: 27)
Industry Applications, IEEE Transactions on     Hybrid Journal   (Followers: 6)
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: 15)
International Journal of Advances in Telecommunications, Electrotechnics, Signals and Systems     Open Access   (Followers: 5)
International Journal of Aerospace Innovations     Full-text available via subscription   (Followers: 17)
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: 14)
International Journal of Electronics     Hybrid Journal   (Followers: 2)
International Journal of Electronics & Data Communication     Open Access   (Followers: 8)
International Journal of Electronics and Telecommunications     Open Access   (Followers: 10)
International Journal of Granular Computing, Rough Sets and Intelligent Systems     Hybrid Journal  
International Journal of High Speed Electronics and Systems     Hybrid Journal  
International Journal of Image, Graphics and Signal Processing     Open Access   (Followers: 7)
International Journal of Nano Devices, Sensors and Systems     Open Access   (Followers: 6)
International Journal of Nanoscience     Hybrid Journal   (Followers: 2)
International Journal of Numerical Modelling:Electronic Networks, Devices and Fields     Hybrid Journal   (Followers: 2)
International Journal of Power Electronics     Hybrid Journal   (Followers: 12)
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: 4)
International Journal on Communication     Full-text available via subscription   (Followers: 12)
International Journal on Electrical and Power Engineering     Full-text available via subscription   (Followers: 7)
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: 6)
Journal of Circuits, Systems, and Computers     Hybrid Journal   (Followers: 2)
Journal of Computational Intelligence and Electronic Systems     Full-text available via subscription  
Journal of Electrical and Electronics Engineering Research     Open Access   (Followers: 13)
Journal of Electrical Bioimpedance     Full-text available via subscription   (Followers: 2)
Journal of Electrical Engineering & Electronic Technology     Hybrid Journal   (Followers: 6)
Journal of Electromagnetic Analysis and Applications     Open Access   (Followers: 5)
Journal of Electromagnetic Waves and Applications     Hybrid Journal   (Followers: 4)
Journal of Electronic Design Technology     Full-text available via subscription   (Followers: 3)
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: 109)
Journal of Intelligent Procedures in Electrical Technology     Open Access   (Followers: 3)
Journal of Low Power Electronics     Full-text available via subscription   (Followers: 6)
Journal of Low Power Electronics and Applications     Open Access   (Followers: 3)
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: 22)
Journal of Power Electronics & Power Systems     Full-text available via subscription   (Followers: 7)
Journal of Semiconductors     Full-text available via subscription   (Followers: 2)
Journal of Sensors     Open Access   (Followers: 18)
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: 6)
Metrology and Measurement Systems     Open Access   (Followers: 4)
Microelectronics and Solid State Electronics     Open Access   (Followers: 13)
Nanotechnology Magazine, IEEE     Full-text available via subscription   (Followers: 31)
Nanotechnology, Science and Applications     Open Access   (Followers: 3)
Networks: an International Journal     Hybrid Journal   (Followers: 4)
Open Journal of Antennas and Propagation     Open Access   (Followers: 4)
Optical Communications and Networking, IEEE/OSA Journal of     Full-text available via subscription   (Followers: 12)
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: 5)
Recent Patents on Telecommunications     Full-text available via subscription   (Followers: 2)
Research & Reviews : Journal of Embedded System & Applications     Full-text available via subscription   (Followers: 3)
Security and Communication Networks     Hybrid Journal   (Followers: 3)
Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of     Hybrid Journal   (Followers: 43)
Semiconductors and Semimetals     Full-text available via subscription  
Sensing and Imaging : An International Journal     Hybrid Journal   (Followers: 1)
Services Computing, IEEE Transactions on     Hybrid Journal   (Followers: 4)
Software Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 53)
Solid-State Circuits Magazine, IEEE     Hybrid Journal   (Followers: 9)
Solid-State Electronics     Hybrid Journal   (Followers: 6)
Superconductor Science and Technology     Hybrid Journal   (Followers: 2)
Synthesis Lectures on Power Electronics     Full-text available via subscription   (Followers: 1)
Technical Report Electronics and Computer Engineering     Open Access  
Telematique     Open Access  
TELKOMNIKA (Telecommunication, Computing, Electronics and Control)     Open Access   (Followers: 5)
Universal Journal of Electrical and Electronic Engineering     Open Access   (Followers: 5)
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: 11)
Електротехніка і Електромеханіка     Open Access  

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Journal Cover IEEE Transactions on Power Electronics
  [SJR: 3.005]   [H-I: 160]   [47 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0885-8993
   Published by IEEE Homepage  [191 journals]
  • IEEE Power Electronics Society
    • Abstract: Provides a listing of current committee members and society officers.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • IEEE Power Electronics Society
    • Abstract: Provides a listing of current staff, committee members and society officers.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Editorial: Reflections on 2016
    • Authors: Brad Lehman;Henry S. H. Chung;
      Pages: 1 - 01
      Abstract: Presents the introductory editorial for this issue of the publication.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • A General Control Method for Multilevel Converters Based on Knapsack
    • Authors: Jalal Amini;Abbas Hooshmand Viki;Ahmad Radan;Mehrdad Moallem;
      Pages: 2 - 10
      Abstract: Switching sequences of multilevel inverters have to be properly chosen based on the desired control criteria such as dc-link voltage regulation, common mode voltage reduction, and other application dependent criteria. Control of a converter to satisfy a desired criterion is challenging, especially in high voltage level converters. This paper proposes a simple control method for multilevel inverters with high modularity such as flying capacitor multilevel inverters, H-bridge multilevel inverters, and modular multilevel inverters. It is shown that the method considerably simplifies generation of the switching sequences and fulfills the desired criteria with a reasonable computational cost. The proposed method is computationally efficient in the sense that its implementation for high voltage level inverters requires the same effort as required for a multilevel inverter with a low number of cells. Other prominent advantages of the proposed control method, compared to earlier methods, include its applicability for multiphase multilevel converters and converters with asymmetrical structure and/or unevenly distributed dc voltages, independence from the level number and structure of the converter, and not requiring a lookup table. These advantages make the proposed scheme well suited for high cell-number converters, mainly utilized in FACTS, HVDC, and power quality applications. Simulation and experimental results are presented which verify the performance of the proposed method.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • A Modular Multilevel Converter With DC Fault Handling Capability and
           Enhanced Efficiency for HVdc System Applications
    • Authors: Rafael Oliveira;Amirnaser Yazdani;
      Pages: 11 - 22
      Abstract: This paper proposes a modular multilevel converter (MMC) topology for high-voltage dc (HVdc) system applications. The proposed MMC employs two half-bridge converters, a cascade of networks that consist of electronic switches, and multiple capacitors. Thus, charged capacitors are inserted in series with the arm current path, for a desired level of the output ac voltage. The switches that must be turned on are judiciously selected for the most efficient current path. The proposed MMC also offers dc-side fault handling capability. The paper compares the proposed MMC with the half-bridge submodule-based MMC, full-bridge submodule-based MMC, and clamp-double submodule-based MMC technologies. It is shown that the proposed MMC is more efficient than the three aforementioned MMC technologies, while it offers the same fault handling capability as that of an equivalent full-bridge-based MMC. Time-domain simulation studies confirm the effectiveness of the proposed MMC under various normal and faulted operating scenarios, using detailed as well as reduced models.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Controlled Transition Full-Bridge Hybrid Multilevel Converter With
           Chain-Links of Full-Bridge Cells
    • Authors: Peng Li;Grain Philip Adam;Derrick Holliday;Barry Williams;
      Pages: 23 - 38
      Abstract: This paper proposes a controlled transition full-bridge (CTFB) hybrid multilevel converter (HMC) for medium and high voltage applications. It employs a full-bridge cell chain-link (FB-CL) between the two legs in each phase to generate multilevel bipolar output voltage. The CTFB-HMC has twice dc voltage utilization or power density of conventional converters due to the bipolar capability of its full-bridge configuration. Hence, for the same power rating and same voltage level number, its total cells per phase are quarter that in modular multilevel converter (MMC), which reduces the hardware installation volume. Also, in the proposed converter, the total device number in the conduction paths is the same as in the half-bridge MMC, leading to low conduction losses. The FB-CL current of the CTFB converter has no dc component, which offers the potential to enhance the transient response. Comparative studies between the CTFB and other multilevel topologies are carried out to clarify its main features. The modulation strategies and parameter sizing of the proposed converter are investigated using a generic case. Simulation and experimental results are used to verify the effectiveness of the proposed approach.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Reliable Modular Multilevel Converter Fault Detection With Redundant
           Voltage Sensor
    • Authors: Ricard Picas;Jordi Zaragoza;Josep Pou;Salvador Ceballos;
      Pages: 39 - 51
      Abstract: This paper presents a fault-tolerant configuration for the modular multilevel converter (MMC). The procedure is able to detect faults in voltage sensors and semiconductor switching devices, and it can reconfigure the system so that it can keep on operating. Both switch and sensor faults can be detected by comparing the output voltage of a set of submodules (SMs), which is measured by a so-called supervisory sensor, with two calculated reference voltages. Faults in the supervisory sensors are also considered. Sensor faults are overcome by using a measuring technique based on estimates that are periodically updated with the voltage measurements of the supervisory sensors. Additional SMs are included in the arms so that the MMC can bypass a faulty SM and continue operating without affecting the output voltage of the phase-leg. Experimental results obtained from a low-power MMC prototype are presented in order to demonstrate the effectiveness of the proposed techniques.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Generation of Higher Number of Voltage Levels by Stacking Inverters of
           Lower Multilevel Structures With Low Voltage Devices for Drives
    • Authors: Viju Nair R;Arun Rahul S;R. Sudharshan Kaarthik;Abhijit Kshirsagar;K. Gopakumar;
      Pages: 52 - 59
      Abstract: This paper proposes a new method of generating higher number of levels in the voltage waveform by stacking multilevel converters with lower voltage space vector structures. An important feature of this stacked structure is the use of low voltage devices while attaining higher number of levels. This will find extensive applications in electric vehicles since direct battery drive is possible. The voltages of all the capacitors in the structure can be controlled within a switching cycle using the switching state redundancies (pole voltage redundancies). This helps in reducing the capacitor size. Also, the capacitor voltages can be balanced irrespective of modulation index and load power factor. To verify the concept experimentally, a nine-level inverter is developed by stacking two five-level inverters and an induction motor is run using V/f control scheme. Both steady state and transient results are presented.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Fifth- and Seventh-Order Harmonic Elimination With Multilevel Dodecagonal
           Voltage Space Vector Structure for IM Drive Using a Single DC Source for
           the Full Speed Range
    • Authors: Mathews Boby;Sumit Pramanick;R. Sudharshan Kaarthik;Arun Rahul S;K. Gopakumar;Loganathan Umanand;
      Pages: 60 - 68
      Abstract: This paper presents a method for generating a multilevel dodecagonal voltage space vector structure using a single dc source for induction motor drives. Multilevel dodecagonal structure combines the advantages of both multilevel and dodecagonal structures, and hence, generates low dv/dt phase voltage along with the elimination of fifth- and seventh-order harmonics over the entire modulation range. This eliminates low-order harmonic currents and prevents the generation of sixth-order torque ripple in the motor. The topology used requires only one dc source making four-quadrant operation of the drive system simpler compared to previously proposed multilevel topologies generating dodecagonal space vector structures. The topology used consists of a three-level flying capacitor (FC) inverter cascaded with a capacitor fed H-bridge. The FC inverter operates at a lower switching frequency and the low-order harmonics are eliminated by the switching action of the cascaded H-bridge inverter. The capacitors in the cascaded H-bridge modules are maintained at a substantially smaller voltage compared to the dc-link voltage and are inherently balanced during the pulsewidth modulation operation. This results in low switching loss, in the FC inverter as well as in the cascaded H-bridge inverter. Experimental results are included to validate the operation of the topology and modulation scheme presented in this paper.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Dual-Bridge LLC Resonant Converter With Fixed-Frequency PWM Control for
           Wide Input Applications
    • Authors: Xiaofeng Sun;Xiaohua Li;Yanfeng Shen;Baocheng Wang;Xiaoqiang Guo;
      Pages: 69 - 80
      Abstract: This paper proposes a dual-bridge (DB) LLC resonant converter for wide input applications. The topology is an integration of a half-bridge (HB) LLC circuit and a full-bridge (FB) LLC circuit. The fixed-frequency pulsewidth-modulated (PWM) control is employed and a range of twice the minimum input voltage can be covered. Compared with the traditional pulse frequency modulation (PFM) controlled HB/FB LLC resonant converter, the voltage gain range is independent of the quality factor, and the magnetizing inductor has little influence on the voltage gain, which can simplify the parameter selection process and benefit the design of magnetic components as well. Over the full load range, zero-voltage switching (ZVS) and zero-current switching (ZCS) can be achieved for primary switches and secondary rectifier diodes, respectively. Detailed analysis on the modulation schedule and operating principle of the proposed converter is presented along with the converter performance. Finally, all theoretical analysis and characteristics are verified by experimental results from a 120-V to 240-V input 24 V/20 A output converter prototype.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • An Improved Phase-Shifted Carrier Modulation Scheme for a Hybrid Modular
           Multilevel Converter
    • Authors: Sizhao Lu;Liqiang Yuan;Kai Li;Zhengming Zhao;
      Pages: 81 - 97
      Abstract: This paper presents an improved phase-shifted carrier pulse width modulation (PSC-PWM) scheme for the hybrid modular multilevel converter (MMC) consisting of half-bridge submodules (HBSMs) and full-bridge submodules (FBSMs). When the traditional PSC-PWM schemes for the HBSMs-based MMC and the FBSMs-based MMC are directly applied to the hybrid MMC, some mismatch pulses will occur on the arm voltages because the HBSMs and the FBSMs have different characteristics. These mismatch pulses not only generate undesirable harmonics on the output voltages, but also induce the significantly uneven loss distributions between the HBSMs and the FBSMs. Therefore, an improved PSC-PWM scheme for the hybrid MMC is proposed in this paper to deal with these issues. The improved PSC-PWM scheme can eliminate the mismatch pluses in the output voltages, alleviate the uneven loss distributions between the HBSMs and the FBSMs, and reduce the total switching loss of the converter. The mathematical analysis of the improved PSC-PWM scheme for the hybrid MMC is conducted and its harmonic characters are investigated. The analysis results are verified and compared with the traditional PSC-PWM scheme by the simulated and experimental results.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Electrified Automotive Powertrain Architecture Using Composite
           DC–DC Converters
    • Authors: Hua Chen;Hyeokjin Kim;Robert Erickson;Dragan Maksimović;
      Pages: 98 - 116
      Abstract: In a hybrid or electric vehicle powertrain, a boost dc–dc converter enables reduction of the size of the electric machine and optimization of the battery system. Design of the powertrain boost converter is challenging because the converter must be rated at high peak power, while efficiency at medium-to-light load is critical for the vehicle system performance. By addressing only some of the loss mechanisms, previously proposed efficiency improvement approaches offer limited improvements in size, cost, and efficiency tradeoffs. This paper shows how all dominant loss mechanisms in automotive powertrain applications can be mitigated using a new boost composite converter approach. In the composite dc–dc architecture, the loss mechanisms associated with indirect power conversion are addressed explicitly, resulting in fundamental efficiency improvements over wide ranges of operating conditions. Several composite converter topologies are presented and compared to state-of-the-art boost converter technologies. It is found that the selected boost composite converter results in a decrease in the total loss by a factor of 2–4 for typical drive cycles. Furthermore, the total system capacitor power rating and energy rating are substantially reduced, which implies potentials for significant reductions in system size and cost.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • A Power Supply Achieving Titanium Level Efficiency for a Wide Range of
           Input Voltages
    • Authors: Werner Konrad;Gerald Deboy;Annette Muetze;
      Pages: 117 - 127
      Abstract: To achieve the highest possible grade for server or computer power supplies in terms of efficiency, various solutions for high line input already exist on the market. In this paper, a new topology is investigated closely, showing that the titanium grade may be achievable at low line input with traditional silicon devices by the utilization of low voltage mosfets, which have an excellent figure of merits, by connecting two converter stages in parallel for low line input or in series for high line input. This paper presents simulation results which are verified with measurements from a developed prototype for 1 kW of power and 12 V output consisting of a triangular current mode power factor correction followed by a well-known phase shifted zero voltage switched bridge. Furthermore, a detailed description of the loss estimation by simulation, enhanced with additional calculations, is presented.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • A Novel Flexible Capacitor Voltage Control Strategy for Variable-Speed
           Drives With Modular Multilevel Converters
    • Authors: Bingyong Tai;Congzhe Gao;Xiangdong Liu;Zhen Chen;
      Pages: 128 - 141
      Abstract: Modular multilevel converter (MMC) is very popular in medium-voltage applications, such as high-voltage direct current transmission, static Var generator, and motor drives. The arm capacitor voltage of MMC is usually constant and the output voltage is adjusted by regulating the pulse width modulation (PWM) index for switches in previous studies. In this paper, a novel flexible capacitor voltage control strategy for MMC as motor drives was proposed, with which the arm capacitor voltage was controlled flexibly according to the motor speed, by regulating the dc component and ac component of the PWM reference signal, and unsymmetrical control was used for the control of the upper arm and the lower arm in MMC. With the proposed control strategy, the circuit efficiency and the precision of the output voltage of the converter could be improved when the motor speed was low, and di/dt and d v/dt of the motor windings could be decreased. These proposals were implemented on a laboratory prototype, and experiments were carried out. The validity of the control strategy under both steady and dynamic states was verified.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • A Voltage Model of p-i-n Diodes at Reverse Recovery Under Short-Time
    • Authors: Yifei Luo;Fei Xiao;Bo Wang;Binli Liu;Yanfei Xia;
      Pages: 142 - 149
      Abstract: Fast switching and large capacity in modern power converters generate large-voltage peak during the diode's reverse-recovery process. Being different from the steady-state reverse recovery, short-time freewheeling of diodes at higher speed switching may generate higher reverse-recovery voltage peak. In this paper, the reverse recovery of p-i-n diodes under short-time freewheeling in a typical power converter circuit is studied with considerations of different initial current of the related IGBTs. By establishing the boundary connections between the turn-on and the turn-off transient stages, a mixed model of the diode's reverse-recovery voltage peak under short-time freewheeling is finally obtained, which combines the physics-based model with the behavior model. Model parameters were then extracted through measurements and circuit extraction methods to relax the complexity. Experiments were performed in a half-bridge inverter unit with 1200-V/50-A IGBTs and p-i-n freewheeling diodes at different short freewheeling time. The accuracy of the proposed model is verified by comparing the simulated waveforms with the measured data. The influence of different initial current on the voltage peak at short-time freewheeling was also evaluated using the proposed model.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Modeling and Optimization of a Zero-Voltage Switching Inverter for High
           Efficiency and Miniaturization
    • Authors: Chengrui Du;Dehong Xu;Ning He;Nan Zhu;
      Pages: 150 - 163
      Abstract: In a zero-voltage switching (ZVS) inverter, high conversion efficiency and miniaturization are expected since switching loss can be dramatically reduced with proper design. In order to realize ZVS condition, auxiliary components such as inductors, capacitors, and switches are embedded in the inverter to implement the function. Since the design of auxiliary components is critical to the ZVS inverter, it is impossible to realize maximum efficiency or minimum size by following the conventional design procedure. This paper introduces an optimized design methodology for a three-phase ZVS inverter with objectives of both high efficiency and miniaturization. Based on the loss models of different commercial IGBT modules under different ZVS conditions, as well as the loss models of auxiliary components and filter inductors, the issue of pursuing highest efficiency and power density is transformed into solving a constrained nonlinear multivariable problem. According to the proposed design methodology, all parameters that influence the efficiency and physical dimensions are considered simultaneously. Thus, the optimized selection of the IGBT module, the parameters of the auxiliary components and the filter inductors would be obtained. A 30-kW three-phase ZVS inverter prototype is built to verify the proposed design method. With proposed design method, the improved prototype has achieved both smaller passive components volume and higher efficiency compared to the former prototype.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Elimination of Low-Frequency Ripples and Regulation of Neutral-Point
           Voltage in Stacked Multicell Converters
    • Authors: Amer M. Y. M. Ghias;Josep Pou;Pablo Acuna;Salvador Ceballos;Alireza Heidari;Vassilios G. Agelidis;Adel Merabet;
      Pages: 164 - 175
      Abstract: This paper introduces a modulation method for the stacked multicell converters (SMCs). The proposed method is implemented using phase-disposition pulse width modulation and is capable of balancing and regulating the voltages of all the capacitors in the topology, i.e., the flying capacitors and the dc-link capacitors. The proposed method is also able to eliminate the low-frequency voltage ripples that may appear in the neutral point (NP) of SMCs. In SMCs with two stacks, the NP voltage level can be generated by direct connection of the output to the dc-link NP, but also using two extra states available. This redundancy is used to regulate the NP voltage. Furthermore, since the proposed method can eliminate the low-frequency voltage ripples in the capacitors, the capacitances of all the capacitors of the SMCs can be reduced, while maintaining high quality of the output voltages and currents. This enables the use of film capacitors. Simulation and experimental results are presented from a three-phase five-level $2times 2$ SMC to verify the effectiveness of the proposed method.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Optimal Space Vector Sequence Investigation Based on Natural Sampling SVM
           for Medium-Voltage Current-Source Converter
    • Authors: Qiang Wei;Bin Wu;Dewei David Xu;Navid R. Zargari;
      Pages: 176 - 185
      Abstract: The device switching frequency of current-source converters (CSCs) in high-power medium-voltage (MV) drive applications is normally around 500 Hz. Conventional space vector modulation (SVM) features fast dynamic response but its output contains low-order harmonics with high magnitudes. Recently, a natural-sampling-based SVM (NS-SVM) with superior low-order harmonics performance has been proposed for MV CSCs. This study further investigates the low-order harmonics performance of different space vector sequences for MV CSCs based on NS-SVM. Dwell times equations based on NS-SVM for each space vector sequence with minimized switching frequency are analyzed and derived; comparisons of different vector sequences in terms of low-order harmonics and load/grid-side total demand distortion performance are thoroughly conducted. Among all the investigated sequences, sequence 2 (SQ2) is the best one; its linear two-step dwell times equations are provided for online implementation. Simulations and experiments are provided to verify its performance.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Improved Power Decoupling Scheme for a Single-Phase Grid-Connected
           Differential Inverter With Realistic Mismatch in Storage Capacitances
    • Authors: Wenli Yao;Xiongfei Wang;Poh Chiang Loh;Xiaobin Zhang;Frede Blaabjerg;
      Pages: 186 - 199
      Abstract: A single-phase differential inverter consists of two elementary dc–dc converters, sharing a common dc source and a common ac output terminal. The other ac terminals of the two converters are connected to the grid in the case of grid-connected applications. The differential inverter has subsequently been shown to have a differential flow path for power transfer and a common-mode path for shifting the usual second-order power oscillation away from the dc source. This capability is referred to as power decoupling, which when implemented properly, may prolong the lifespan of the dc source. Existing studies related to power decoupling using a differential inverter have however focused on developing control schemes with equal storage capacitances assumed for the two elementary converters. This is unquestionably not realistic since the two capacitances will vary in practice. It is therefore the intention of this paper to quantify ac and dc imperfections experienced by the differential inverter when storage mismatch occurs. A simple improved scheme is then proposed for raising performance of the differential inverter (or the differential rectifier where desired). Simulation and experimental results provided have verified the computation and control scheme developed.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Parameter Design of a Novel Series-Parallel-Resonant LCL Filter for
           Single-Phase Half-Bridge Active Power Filters
    • Authors: Jingyang Fang;Guochun Xiao;Xu Yang;Yi Tang;
      Pages: 200 - 217
      Abstract: This paper proposes a novel high-order passive filter, i.e., series-parallel-resonant LCL (SPRLCL) filter, for single-phase half-bridge active power filters. The proposed SPRLCL filter consists of a series resonance introduced by adding a small inductor to the capacitor branch loop and a parallel resonance by paralleling a small capacitor with the gird-side inductor. Three design methods are proposed to fine tune the parameters of the SPRLCL filter. Design method I and method II enable the SPRLCL filter to attenuate more switching-frequency and double switching-frequency current harmonics than LCL or LLCL filters, while with design method III, the SPRLCL filter can be more robust against filter parameter variations. In order to achieve a better damping performance and facilitate the design of active damping control, the dominant resonance frequency of the proposed filter is set at one-third of the system sampling frequency. Based on this, a comprehensive parameter design process of the SPRLCL filter is presented, where the variation of source inductance is also considered. A proportional plus repetitive current-loop controller is designed to ensure system control stability and satisfactory harmonic compensation. Simulation and experimental results are finally presented to validate the feasibility of the theoretical analysis.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Q Controllable Antenna as a Potential Means for Wide-Area Sensing and
           Communication in Wireless Charging via Coupled Magnetic Resonances
    • Authors: Sousuke Nakamura;Masato Namiki;Yasuhiro Sugimoto;Hideki Hashimoto;
      Pages: 218 - 232
      Abstract: Recently, wireless charging via coupled magnetic resonances gains attention because it has a potential of efficient mid-range wireless charging. Here, functions such as sensing at the transmitter and wireless communication from the target are the essential elements to realize the standard wireless charging system. Currently, the sensing and communication protocol of hardware (i.e., high-frequency power source and antenna configuration) compatible with wireless charging is gaining attention in terms of cost and space reduction due to the use of common components in multiple functions. However, these protocols have the problem of narrow effective areas. Therefore, this paper presents a method for wide-area sensing and communication with slight modification of the configuration. The basic concept is to expand the effective area related to antenna Q factor by using the Q controllable antenna acting as though the Q factor increased. The underlying theory was described with electric circuit theory. The experimental results showed that the Q factor can be increased until the resonance collapses, and the increase of Q factor has the potential to widen the effective area of sensing and communication.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • An Online Transformerless Uninterruptible Power Supply (UPS) System With a
           Smaller Battery Bank for Low-Power Applications
    • Authors: Muhammad Aamir;Saad Mekhilef;
      Pages: 233 - 247
      Abstract: Uninterruptible power supplies (UPS) are widely used to provide reliable and high-quality power to critical loads in all grid conditions. This paper proposes a nonisolated online UPS system. The proposed system consists of bridgeless PFC boost rectifier, battery charger/discharger, and an inverter. A new battery charger/discharger has been implemented which ensures the bidirectional flow of power between dc link and battery bank, reducing the battery bank voltage to only 24V, and regulates the dc-link voltage during the battery power mode. Operating batteries in parallel improves the battery performance and resolve the problems related to conventional battery banks that arrange batteries in series. A new control method, integrating slide mode and proportional-resonant control, for the inverter has been proposed which regulates the output voltage for both linear and nonlinear loads. The controller exhibits excellent performance during transients and step changes in load. The operating principle and experimental results of 1-kVA prototype have been presented for validation of the proposed system.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • A Medium-Frequency Transformer-Based Wind Energy Conversion System Used
           for Current-Source Converter-Based Offshore Wind Farm
    • Authors: Qiang Wei;Bin Wu;Dewei Xu;Navid Reza Zargari;
      Pages: 248 - 259
      Abstract: Offshore wind farms with series-interconnected structures are promising configurations because bulky and costly offshore substations can be eliminated. In this paper, a medium-frequency transformer (MFT)-based wind energy conversion system is proposed for such wind farms based on current source converters. The presented configuration consists of a medium-voltage permanent magnet synchronous generator that is connected to a low-cost passive rectifier, an MFT-based cascaded converter, and an onshore current source inverter. Apart from fulfilling traditional control objectives (maximum power point tracking, dc-link current control, and reactive power regulation), this study endeavors to ensure evenly distributed power and voltage sharing among the constituent modules given the cascaded structure of the MFT-based converter. In addition, this paper thoroughly discusses the characteristic of decoupling between the voltage/power balancing of the modular converter and the other control objectives. Finally, both simulation and experimental results are provided to reflect the performance of the proposed system.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Performance Analysis of the Zero-Voltage Vector Distribution in
           Three-Phase Four-Switch Converter Using a Space Vector Approach
    • Authors: Zhiyong Zeng;Weiyi Zheng;Rongxiang Zhao;
      Pages: 260 - 273
      Abstract: The ac current ripple, the common voltage (CMV), and the current stress on the dc-link capacitor are defined as the critical performance indicators of the three-phase four-switch (TPFS) converter, and the effect of the zero-voltage vector distribution on these crucial indicators is investigated comprehensively in the proposed paper. A unified space vector modulation (SVM) approach, including the special pulsewidth-modulated (PWM) signal logic, is developed to facilitate the performance analysis of the zero-voltage vector distribution. Then, a novel approach based on the nonorthogonal stationary frame is proposed to facilitate the sector identification. Furthermore, because of the asymmetry of the harmonics of the three-phase output voltages, an overall current performance indicator, the total three-phase ac current ripple, is defined to assess the overall performance of the three-phase ac current. In addition, the dc-link capacitor current and CMV per sampling period are investigated; different ineffective duty ratio allocations result in the varied CMVs and capacitor currents. Moreover, due to the complexity of the Fourier analysis method, the root-mean-square (rms) values of the crucial indicators are adopted to evaluate the relative merits of various zero-voltage vector distributions. The proposed rms value equations are straightforward for the evaluation of the effect of the zero-voltage vector distribution on these crucial indicators. Experimental results confirm the accuracy and usefulness of the proposed performance analysis.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Impedance-Phased Dynamic Control Method for Grid-Connected Inverters in a
           Weak Grid
    • Authors: Xin Chen;Yang Zhang;Shanshan Wang;Jie Chen;Chunying Gong;
      Pages: 274 - 283
      Abstract: A power distribution grid exhibits the characteristics of a weak grid owing to the existence of scattered high-power distributed power-generation devices. The grid impedance affects the robust stability of grid-connected inverters, leading to harmonic resonance, or even instability in the system. Therefore, a study of the stability of grid-connected inverters with high grid impedance based on impedance analysis is presented in this paper. The output impedance modeling of an LCL-type single-phase grid-connected inverter is derived, where the effects of the PLL loop and the digital control delays on the output impedance characteristics have been taken into account. To enhance the stability of grid-connected inverters with different grid impedance, a novel impedance-phased compensation control strategy is proposed by increasing the phase margin of the grid-connected inverters. Specifically, a detailed implementation and parameter design of the impedance-phased compensation control method is depicted. Finally, an impedance-phased dynamic control scheme combined with online grid impedance measurement is introduced and also verified by the experiment results.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Direct Stator Current Vector Control Strategy of DFIG Without Phase-Locked
           Loop During Network Unbalance
    • Authors: Peng Cheng;Heng Nian;Chao Wu;Z. Q. Zhu;
      Pages: 284 - 297
      Abstract: This paper proposes a direct stator current vector control strategy of a doubly fed induction generator (DFIG) without phase-locked loop (PLL) during network unbalance. In the proposed control strategy, a virtual phase angle produced by the nominal frequency is used for coordinate transformations instead of the actual voltage one estimated by the PLL. Since the calculation of the commanded stator currents is based on the instantaneous power theory regardless of the generator parameters, it can greatly reduce the parameter dependence of the control system. Then, for a satisfactory grid synchronization, an improved synchronization method is proposed. It can smoothly produce the stator voltage with no overshoot voltage and no parameter dependence. During network unbalance, a reduced-order vector integrator is used to directly regulate the pulsating components without the complex calculations of the commanded current values and the sequential separations of the voltages and currents. Meanwhile, four alternative control targets can be achieved for the DFIG during network unbalance. Furthermore, the control performance, including the control system stability, the robustness against frequency disturbances and parameter deviations, and the rejection of voltage unbalance, are fully analyzed. Finally, the experimental results are given to validate the effectiveness of the proposed control strategy.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Voltage and Frequency Grid Support Strategies Beyond Standards
    • Authors: Emanuel Serban;Martin Ordonez;Cosmin Pondiche;
      Pages: 298 - 309
      Abstract: In recent years, with a higher penetration of renewable distributed generators into the ac grid network, the risk of grid instabilities and vulnerabilities has increased. This paper proposes grid support strategies that can be used to alleviate the grid frequency–voltage variations, which are indicators of the imbalance between power generation and consumption within an ac network. The proposed strategies to support grid stability in the event of frequency–voltage variation go beyond recent standards and provide extended functionalities. The preconfigured set points of active power-frequency P(f) strategy features the control of the converter's power flow direction with an adjustable power gradient transition between grid-feeding and force charge as grid loading, in response to grid frequency deviation. The distributed power generators are represented by an energy storage converter, with the capacity to discharge and charge the electrical energy storage (EES) element, primarily for grid support purposes. The EES energy storage is configured for later usage when the grid requires active power support, under line frequency deviation, used under normal conditions, or during on-peak tariff high-demand daytime hours (energy shifting for TOU, ac load shave). In addition to grid support enhancement, the P(f) strategy is combined with reactive power-voltage Q(v ) control to attempt to correct frequency and voltage deviations in a collective impact of distributed generators operation for grid stabilization purposes. The P(f) − Q (v) strategy provides an automatic active/reactive power generate/receive preconfigured control, in response to frequency–voltage deviations, in order to support the grid and prevent netwo-k instabilities. The proposed control strategy for local frequency assist and voltage assist is applicable for single and three-phase grid converters interfaced with energy storage systems. Simulations and experimental results, obtained using a single-phase 6 kVA four-quadrant EES converter, are presented to validate the proposed P( f) and Q(v) grid support strategies.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • A Sensitivity-Improved PFM LLC Resonant Full-Bridge DC–DC Converter With
           LC Antiresonant Circuitry
    • Authors: Tomokazu Mishima;Hiroto Mizutani;Mutsuo Nakaoka;
      Pages: 310 - 324
      Abstract: An LLC resonant circuit-based full-bridge dc–dc converter with an LC antiresonant tank for improving the performance of pulse frequency modulation (PFM) is proposed in this paper. The proposed resonant dc–dc converter, named as LLC-LC converter, can extend a voltage regulation area below the unity gain with a smaller frequency variation of PFM by the effect of the antiresonant tank. This advantageous property contributes for protecting overcurrent in the case of the short-circuit load condition as well as the start-up interval in the designed band of switching frequency. The circuit topology and operating principle of the proposed converter is described, after which the design procedure of the operating frequency and circuit parameters is presented. The performances on the soft switching and the steady-state PFM characteristics of the LLC-LC converter are evaluated under the open-loop control in experiment of a 2.5-kW prototype, and its actual efficiency is compared with an LLC converter prototype. For revealing the effectiveness of the LLC-LC resonant circuitry, voltages and currents of the series and antiresonant tanks are analyzed, respectively, with state-plane trajectories based on calculation and experiment, whereby the power and energy of each resonant tank are demonstrated. Finally, the feasibility of the proposed converter is evaluated from the practical point of view.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Multitrack Power Conversion Architecture
    • Authors: Minjie Chen;Khurram K. Afridi;Sombuddha Chakraborty;David J. Perreault;
      Pages: 325 - 340
      Abstract: This paper introduces a MultiTrack power conversion architecture that represents a new way of combining switched-capacitor circuits and magnetics. The MultiTrack architecture takes advantages of the distributed power processing concept and a hybrid switched-capacitor/magnetics circuit structure. It reduces the voltage ratings on devices, reduces the voltage regulation stress of the system, improves the component utilization, and reduces the sizes of passive components. This architecture is suitable to dc–dc and grid-interface applications that require both isolation and wide voltage conversion range. An 18–80 V input, 5 V, 15 A output, 800 kHz, 0.93 in $^2$ (1/16 brick equivalent) isolated dc–dc converter has been built and tested to verify the effectiveness of this architecture. By employing the MultiTrack architecture, utilizing GaN switches, and operating at higher frequencies, the prototype converter achieves a power density of 457.3 W/in$^3$ and a peak efficiency of 91.3%. Its power density is 3$times$ higher than the state-of-the-art commercial converters with comparable efficiency across the wide operation range.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Comparative Analysis of Two-Coil and Three-Coil Structures for Wireless
           Power Transfer
    • Authors: Jian Zhang;Xinmei Yuan;Chuang Wang;Yang He;
      Pages: 341 - 352
      Abstract: With the development of electric vehicles and consumer electronics, wireless power transfer (WPT) is becoming a popular technology. Recently, magnetic resonant coupling has been considered to be the most effective and attractive WPT approach, and the two-coil structure is the most widely used for magnetic resonant coupling. It has been recently reported that the system's energy efficiency can be improved by a three-coil structure. In this paper, the three-coil structure is compared with the two-coil structure based on circuit theory. Simplified circuit models of the two- and three-coil structures are proposed to give a more intuitive and comprehensive analysis of the energy efficiency differences between the two structures. With the simplified model, the condition for a three-coil structure obtaining higher energy efficiency over its two-coil counterpart is derived, and the analysis shows that the WPT system with higher energy efficiency within a wider range of loads can be achieved by properly designed three-coil systems. Additionally, it also shows that the three-coil system has the significant advantage of reducing the current stress and the electromagnetic field emission that is caused by misalignments. The theoretical analysis is confirmed by both simulation and experimental results.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • A Quasi-Resonant Current-Fed Converter With Minimum Switching Losses
    • Authors: Sina Salehi Dobakhshari;Jafar Milimonfared;Meghdad Taheri;Hadi Moradisizkoohi;
      Pages: 353 - 362
      Abstract: A quasi-resonant dc–dc converter with high voltage gain and low current stresses on switches is proposed in this paper. This converter preserved inherent advantages of current-fed structures, for instance, zero magnetizing dc offset, low input ripple, and low transformer turn ratio. Moreover, by employing the active-clamp circuit, the voltage spikes across the main switch, due to the existence of leakage inductance of the isolating transformer, is absorbed, and switches work in zero voltage switching. Since quasi-resonant switching strategy is employed, turn-off current (TOC) and losses of switches are considerably reduced. Because of zero current switching (ZCS), reverse recovery problem of diodes is alleviated. Experimental results on a 150-W prototype are provided to validate the proposed concept.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Modeling and Pareto Optimization of On-Chip Switched Capacitor Converters
    • Authors: Toke M. Andersen;Florian Krismer;Johann W. Kolar;Thomas Toifl;Christian Menolfi;Lukas Kull;Thomas Morf;Marcel Kossel;Matthias Brändli;Pier Andrea Francese;
      Pages: 363 - 377
      Abstract: The operation and efficiency of on-chip switched-capacitor (SC) converters are highly affected by the parasitic bottom plate capacitor present in on-chip capacitor technologies. Existing modeling frameworks do not in a comprehensive manner take the effect of the bottom plate capacitor on converter operation and efficiency into account. This paper extends an existing SC state space modeling framework to include the bottom plate capacitor. The developed model is used in a Pareto optimization procedure to optimally select the component values of a 2:1 on-chip SC converter. Implemented in a 32 nm SOI CMOS technology that features the high-density deep trench capacitor, the on-chip converter achieves $86%$ maximum efficiency at $4.6,text{W}/text{m}text{m}^2$ power density while converting from a 1.8 V input voltage to 830 mV output voltage.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • A 10 W On-Chip Switched Capacitor Voltage Regulator With Feedforward
           Regulation Capability for Granular Microprocessor Power Delivery
    • Authors: Toke M. Andersen;Florian Krismer;Johann W. Kolar;Thomas Toifl;Christian Menolfi;Lukas Kull;Thomas Morf;Marcel Kossel;Matthias Brändli;Pier Andrea Francese;
      Pages: 378 - 393
      Abstract: Granular power delivery with per-core regulation for microprocessor power delivery has the potential to significantly improve the energy efficiency of future data centers. On-chip switched capacitor converters can enable such granular power delivery with per-core regulation given a high efficiency, high power density, fast response time, and high output power converter design. This paper details the implementation of an on-chip switched capacitor voltage regulator in a $32,mathrm{n}mathrm{m}$ SOI CMOS technology with deep trench capacitors. A novel feedforward control for reconfigurable switched capacitor converters is presented. The feedforward control reduces the output voltage droop following a transient load step. This leads to a reduced minimum microprocessor supply voltage, thereby reducing the overall power consumption of the microprocessor. The implemented on-chip switched capacitor voltage regulator provides a $0.7-1.1$ V output voltage from $1.8$ V input. It achieves a $85.1%$ maximum efficiency at $3.2,mathrm{W}mathrm{/}mathrm{m}mathrm{m}^2$ power density, a subnanosecond response time with improved minimum supply voltage capability, and a maximum output power of $10,mathrm{W}$. For an output voltage of $850,mathrm{m}mathrm{V}$, the feedforward control reduces the required voltage overhead by $60,mathrm{m}mathrm{V}$ for a transient load step from $10%$ to $100%$ of the nominal load. This can reduce the overall power consumption of the microprocessor by $7%$.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Higher Order Compensation for Inductive-Power-Transfer Converters With
           Constant-Voltage or Constant-Current Output Combating Transformer
           Parameter Constraints
    • Authors: Xiaohui Qu;Yanyan Jing;Hongdou Han;Siu-Chung Wong;Chi K. Tse;
      Pages: 394 - 405
      Abstract: Compensation is crucial for improving performance of inductive-power-transfer (IPT) converters. With proper compensation at some specific frequencies, an IPT converter can achieve load-independent constant output voltage or current, near zero reactive power, and soft switching of power switches simultaneously, resulting in simplified control circuitry, reduced component ratings, and improved power conversion efficiency. However, constant output voltage or current depends significantly on parameters of the transformer, which is often space constrained, making the converter design hard to optimize. To free the design from the constraints imposed by the transformer parameters, this paper proposes a family of higher order compensation circuits for IPT converters that achieves any desired constant-voltage or constant-current (CC) output with near zero reactive power and soft switching. Detailed derivation of the compensation method is given for the desired transfer function not constrained by transformer parameters. Prototypes of CC IPT configurations based on a single transformer are constructed to verify the analysis with three different output specifications.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Performance Evaluation of Split Output Converters With SiC MOSFETs and SiC
           Schottky Diodes
    • Authors: Qingzeng Yan;Xibo Yuan;Yiwen Geng;Apollo Charalambous;Xiaojie Wu;
      Pages: 406 - 422
      Abstract: The adoption of silicon carbide (SiC) MOSFETs and SiC Schottky diodes in power converters promises a further improvement of the attainable power density and system efficiency, while it is restricted by several issues caused by the ultrafast switching, such as phase-leg shoot-through (“crosstalk” effect), high turn-on losses, electromagnetic interference (EMI), etc. This paper presents a split output converter, which can overcome the limitations of the standard two-level voltage source converters when employing the fast-switching SiC devices. A mathematical model of the split output converter has been proposed to reveal how the split inductors can mitigate the crosstalk effect caused by the high switching speed. The improved switching performance (e.g., lower turn-on losses) and EMI benefit have been demonstrated experimentally. The current freewheeling problem, the current pulses and voltage spikes of the split inductors, and the disappeared synchronous rectification are explained in detail both experimentally and analytically. The results show that the split output converter can have lower power device losses compared with the standard two-level converter at high switching frequencies. However, the extra losses in the split inductors may impair the efficiency of the split output converter, which is verified by experiments in the continuous operating mode. A 95.91% efficiency has been achieved by the split output converter at the switching frequency of 100 kHz with suppressed crosstalk, lower turn-on losses, and reduced EMI.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • A Dual-Mode Driver IC With Monolithic Negative Drive-Voltage Capability
           and Digital Current-Mode Controller for Depletion-Mode GaN HEMT
    • Authors: Yue Wen;Matthias Rose;Ryan Fernandes;Ralf Van Otten;Henk Jan Bergveld;Olivier Trescases;
      Pages: 423 - 432
      Abstract: This work presents a driver and controller integrated circuit (IC) for depletion-mode gallium nitride (GaN) high-electron-mobility transistors (HEMTs). The dual-mode driver can be configured for cascode-drive (CD) or HEMT-drive (HD) mode. In the CD mode, a cascode low-voltage DMOS is driven to achieve high-speed normally OFF operation. An active clamping circuit is proposed for the DMOS breakdown protection. In the HD mode, an HEMT gate driver with negative drive-voltage capability and programmable slope control is presented. A digital peak current-mode controller is also integrated with the dual-mode driver. The IC was implemented in a 140-nm automotive bipolar-CMOS-DMOS silicon-on-insulator process. The driver/controller IC is copackaged with an optimized 600-V GaN HEMT fabricated in a GaN-on-Si process. The solution was verified to operate at up to 1 MHz in a 35-W boost converter prototype and achieves a programmable switching-node $dv/dt$ of up to 20 V/ns. To the best of the author's knowledge, this is the first monolithic integration of a cascode MOSFET, device driver, and digital current-mode controller that is designed specifically for high-voltage GaN devices.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • High-Efficiency Asymmetric Forward-Flyback Converter for Wide Output Power
    • Authors: Hyeon-Seok Lee;Hyung-Jin Choe;Seok-Hyeong Ham;Bongkoo Kang;
      Pages: 433 - 440
      Abstract: This paper proposes an asymmetric forward-flyback dc–dc converter that has high power-conversion efficiency $eta _{e}$ over a wide output power range. To solve the problem of ringing in the voltage of the rectifier diodes and the problem of duty loss in the conventional asymmetric half-bridge (AHB) converter, the proposed converter uses a voltage doubler structure with a forward inductor $L_{f}$ in the second stage, instead of using the transformer leakage inductance, to control output current. $L_{f}$ resonates with the capacitors in the voltage doubler to achieve a zero-voltage turn-on of switches and a zero-current turn-off of diodes for a wide output power range. The proposed converter could operate at a wider input voltage range than the other AHB converters. $eta _{e}$ was measured as 95.9% at output power $P_{O} = 100$ W and as 90% at $P_{O} = 10$ W, when the converter was operated at input voltage 390 V, output voltage 142 V, and switching frequency 100 kHz.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Cu@Sn Core–Shell Structure Powder Preform for High-Temperature
           Applications Based on Transient Liquid Phase Bonding
    • Authors: Tianqi Hu;Hongtao Chen;Mingyu Li;Zhenqing Zhao;
      Pages: 441 - 451
      Abstract: This paper presents a novel die-attach material for high-temperature applications based on transient liquid phase (TLP) bonding. Cu particles are electroless plated with Sn to achieve Cu@Sn structure, and the fabricated Cu@Sn particles are compressed into preforms for die attachment. This material can be reflowed at a low temperature (
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Steady-State Simulation of LCI-Fed Synchronous Motor Drives Through a
           Computationally Efficient Algebraic Method
    • Authors: Sobhan Mohamadian;Alberto Tessarolo;Simone Castellan;Abbas Shoulaie;
      Pages: 452 - 470
      Abstract: Wound-field synchronous motors (WFSMs) fed by load-commutated inverters (LCIs) are widely used for high-power applications in many fields like ship propulsion, oil and gas industry, and pumped-storage hydropower generation. Several design architectures exist for LCI drives, depending on the number of LCIs and their dc-link connection as well as on the number of WFSM phase count. The prediction of LCI drive performance at steady state is important in the design stage, especially in regard to the prediction of the torque pulsations, which can give rise to serious mechanical resonance issues. This paper proposes an algebraic method to simulate the steady-state behavior of LCI drives in all their configurations of practical interest. Compared to conventional dynamic simulation approaches based on differential equation solution, the method is much more computationally efficient and requires a very limited knowledge of system parameters. Its accuracy is experimentally assessed by comparison against measurements taken on a real LCI drive arranged according to various possible schemes. Furthermore, the advantages of the proposed algebraic method over the dynamic simulations are highlighted by comparison against the simulation results on a high-power LCI-fed WFSM drive in MATLAB/Simulink environment.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Design of Maximum Efficiency Tracking Control Scheme for Closed-Loop
           Wireless Power Charging System Employing Series Resonant Tank
    • Authors: Tae-Dong Yeo;DukSoo Kwon;Seung-Tae Khang;Jong-Won Yu;
      Pages: 471 - 478
      Abstract: This paper presents a maximum efficiency tracking control scheme for a closed-loop wireless power charging (WPC) system for wireless charging of mobile devices. Generally, wireless charging systems need a precise output voltage and current with the highest possible efficiency. In an open-loop system, output voltage and efficiency depend strongly on the coupling coefficient and load condition. Alternatively, a closed-loop WPC system has a constant output voltage against coupling and load variations. Many studies have been carried out regarding closed-loop systems. However, those previous studies have the drawback of efficiency degradation. In this paper, we propose a maximum efficiency tracking control scheme to achieve the highest possible efficiency. Therefore, the proposed WPC system satisfies both the requirements of a constant output voltage and high efficiency. The proposed control scheme determines the current of the transmitter based on the data received by the receiver via Bluetooth. For validation, the proposed WPC system was implemented at 6.78 MHz using loosely coupled series–series resonant coils, and we verified that the proposed system can track the maximum efficiency while maintaining a constant output voltage.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Finite-State Predictive Torque Control of Induction Motor Supplied From a
           Three-Level NPC Voltage Source Inverter
    • Authors: Md. Habibullah;Dylan Dah-Chuan Lu;Dan Xiao;Muhammed Fazlur Rahman;
      Pages: 479 - 489
      Abstract: Finite-state predictive torque control (FS-PTC) of an induction motor (IM) drive has been widely investigated for two-level voltage source inverter recently. This control method suffers from high and variable switching frequencies in a wide range, due to the limited number of available voltage vectors of the power converter. In order to take advantage of multilevel inverter drives which offer the benefits of low harmonic distortion of the stator currents, torque ripple, and low switching frequency, this paper proposes the integration of the FS-PTC with a three-level neutral-point clamped (3L-NPC) inverter driven IM drive. The drawback inherited from the topology of 3L-NPC voltage source inverter (VSI), such as neutral-point voltage, is easily handled by treating it as a variable to the cost function. Similarly, apart from the inverter topology itself, the average switching frequency is reduced further, and is maintained almost constant over a wide speed range. The effectiveness of the proposed FS-PTC in terms of torque and flux responses, capacitor voltage balancing, and low average switching frequency is validated through experimental results.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • An Inverter Nonlinearity-Independent Flux Observer for Direct
           Torque-Controlled High-Performance Interior Permanent Magnet Brushless AC
    • Authors: Mikail Koç;Jiabin Wang;Tianfu Sun;
      Pages: 490 - 502
      Abstract: This paper introduces a novel flux observer for direct torque controlled interior permanent magnet brushless AC (IPM-BLAC) drives over a wide speed range including standstill. The observer takes machine nonlinearities into account and is independent of inverter nonlinearities, dead time, and armature resistance variation at steady states since such inaccuracies are compensated quickly by measured phase currents. Magnetic saturations in the stator and rotor cores, cross-coupling effects of flux linkages of the motor, and spatial harmonics in the magnetomotive force are all considered in the novel scheme. There is no filter; hence, no delays and oscillatory responses like in conventional schemes where filters are employed to prevent integrator drift issue. Superiority of the observer when compared to the state-of-the-art schemes has been illustrated by both extensive simulations and experimental results of a 10-kW IPM-BLAC machine designed for traction applications.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Design Optimization of Hybrid-Switch Soft-Switching Inverters Using
           Multiscale Electrothermal Simulation
    • Authors: John Reichl;Jih-Sheng Lai;Allen Hefner;José M. Ortiz-Rodríguez;Tam Duong;
      Pages: 503 - 514
      Abstract: A multiscale electrothermal simulation approach is presented to optimize the design of a hybrid switch soft-switching inverter using a library of dynamic electrothermal component models parameterized in terms of electrical, structural, and material properties. Individual device area, snubber capacitor, and gate drive timing are used to minimize the total loss of the soft-switching inverter module subject to the design constraints including total device area and minimum on-time consideration. The proposed multiscale electrothermal simulation approach allows for a large number of parametric studies involving multiple design variables to be considered, drastically reducing simulation time. The optimized design is then compared and contrasted with an already existing design from the Virginia Tech Freedom Car Project using the generation II module. It will be shown that the proposed approach improves the baseline design by 16% in loss and reduces the cooling requirements by 42%. Validation of the electrical and thermal device models against measured data is also provided.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Impact of Postfault Flux Adaptation on Six-Phase Induction Motor Drives
           With Parallel Converters
    • Authors: Ignacio Gonzalez-Prieto;Mario J. Duran;Federico Barrero;Mario Bermudez;Hugo Guzmán;
      Pages: 515 - 528
      Abstract: The redundancy of multiphase drives provides an inherent fault-tolerant capability that is appreciated in applications with a complicated corrective maintenance or safety-critical requirements. Fault restrictions, however, force the system to be reconfigured to operate in a smooth and efficient manner. Previous works have been focused on the optimization of current waveforms to generate an undisturbed operation but still maintaining the prefault rated flux settings. This study shows that efficient controllers can improve the postfault performance in six-phase induction machines supplied by parallel-connected converters if offline optimization is used to obtain a variable reference flux. Theoretical and experimental results confirm that the proposed flux adaptation method provides higher torque/power capability, lower degree of imbalance in the current sharing between windings and efficiency improvement.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Design of Inductors With Significant AC Flux
    • Authors: Zhemin Zhang;Khai D. T. Ngo;Jeff L. Nilles;
      Pages: 529 - 539
      Abstract: A design methodology is introduced to select a minimum core volume for an inductor or coupled inductors experiencing appreciable core loss. The geometric constant (Kgac) has been found to be a power function of the core volume for commercial toroidal, ER, and PQ cores, permitting the total loss to be expressed as a direct function of the core volume. The inductor is designed to meet specific loss or thermal constraints. An iterative procedure is described in which 2-D or 3-D proximity effects are first neglected and then subsequently incorporated via finite-element simulation. The methodology is demonstrated for coupled inductors in a 5-MHz converter in critical conduction mode. The core loss is verified using rectangular excitation and the winding loss is inferred from thermal measurements.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Two-Dimensional Gapping to Reduce Light-Load Loss of Point-of-Load
    • Authors: Ting Ge;Khai D. T. Ngo;Jim Moss;
      Pages: 540 - 550
      Abstract: Point-of-load converter at light load has low efficiency owing to the “fixed losses” such as core loss and ac winding loss. This paper focuses on two-dimensional (2-D) gapping of a ferrite core to shape inductance versus load current to reduce inductor loss at light load. Since the maximum inductance of conventional stepped gap is limited by the cross-sectional area of the thin gap, a 2-D gap is formed by joining two orthogonal gaps to gain flexibility. Higher inductance is achieved at light load compared with uniform-gap and stepped-gap geometries having the same volume and dc resistance. AC resistance is reduced at light load thanks to a magnetic path that steers ac flux away from the winding. Two C-cores with 2-D gap were fabricated and tested on a buck converter with 50% reduced total inductor loss at 10% load current.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • A 300-V Ultra-Low-Specific On-Resistance High-Side p-LDMOS With
           Auto-Biased n-LDMOS for SPIC
    • Authors: Bo Yi;Xingbi Chen;
      Pages: 551 - 560
      Abstract: In this paper, a high-side p-channel LDMOS (p-LDMOS) with an auto-biased n-channel LDMOS (n-LDMOS) based on Triple-RESURF technology is proposed. The p-LDMOS utilizes both carriers to conduct the on-state current; therefore, the specific on-resistance ($R_{{rm on},{rm sp}}$ ) can be much reduced because of much higher electron mobility. The simulation result shows that the proposed 300-V p-LDMOS obtains a $R_{{rm on},{rm sp}}$ of 16.97 mΩ/cm2, which is about 65% reduced compared with the Triple-RESURF silicon limit and is comparable to an optimized n-LDMOS (BV = 340 V, $R_{{rm on},{rm sp}} = 18$ mΩ/cm2 ). In addition, due to larger current capability, the active area of the proposed p-LDMOS is only about one third of an optimized Triple-RESURF p-LDMOS. The turn-on ($t_{r}$ ) and turn-off time ($t_{f}$) are reduced by 51.2% and 40.0%, compared to the optimized Triple-RESURF p-LDMOS, respectively.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Finite-Element Analysis of Coupled Electro-Thermal Problems With Strong
           Scale Separation
    • Authors: Sebastian Eiser;Mirko Bernardoni;Michael Nelhiebel;Manfred Kaltenbacher;
      Pages: 561 - 570
      Abstract: We present a finite-element analysis of the coupled electro-thermal behavior of a mm $^2$-sized power DMOS device, with a focus on resolving µm-sized structures. For a reliable power technology, the predictions of current and temperature distributions under self-heating are vital for reaching long device lifetime. Two aspects of our approach are unique: First, we have integrated the active region of the DMOS into the finite-element program code as a nonlinear voltage and temperature dependent tripole, incorporating local biasing and temperature conditions. Second, to model small features like defects or process-induced imperfections in sufficient detail, we use the Nitsche-type nonmatching grid technique to include the substantially finer meshed microscale geometry. This allows us to study very local changes in temperature and biasing conditions, which are normally not accessible. The methodology is applied to a state-of-the-art power technology device with integrated current sensor to validate the methodology. Good agreement is found between results and experiments.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Investigation of Gallium Nitride Devices in High-Frequency LLC Resonant
    • Authors: Weimin Zhang;Fred Wang;Daniel J. Costinett;Leon M. Tolbert;Benjamin J. Blalock;
      Pages: 571 - 583
      Abstract: Newly emerged gallium nitride (GaN) devices feature ultrafast switching speed and low on-state resistance that potentially provide significant improvements for power converters. This paper investigates the benefits of GaN devices in an LLC resonant converter and quantitatively evaluates GaN devices’ capabilities to improve converter efficiency. First, the relationship of device and converter design parameters to the device loss is established based on an analytical model of LLC resonant converter operating at the resonance. Due to the low effective output capacitance of GaN devices, the GaN-based design demonstrates about 50% device loss reduction compared with the Si-based design. Second, a new perspective on the extra transformer winding loss due to the asymmetrical primary-side and secondary-side current is proposed. The device and design parameters are tied to the winding loss based on the winding loss model in the finite element analysis (FEA) simulation. Compared with the Si-based design, the winding loss is reduced by 18% in the GaN-based design. Finally, in order to verify the GaN device benefits experimentally, 400- to 12-V, 300-W, 1-MHz GaN-based and Si-based LLC resonant converter prototypes are built and tested. One percent efficiency improvement, which is 24.8% loss reduction, is achieved in the GaN-based converter.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Measurement of IGBT High-Frequency Input Impedance in Short Circuit
    • Authors: Carmine Abbate;Giovanni Busatto;Annunziata Sanseverino;Francesco Velardi;Sara Iavarone;Cesare Ronsisvalle;
      Pages: 584 - 592
      Abstract: Insulated-gate bipolar transistors (IGBTs) operated in short circuit become instable in certain driving and load conditions. The induced oscillations can compromise robustness and reliability of the entire power converter. The stability of the device inserted in a real system can be analyzed using the theory of linear oscillators that requires the knowledge of input or output impedance of the device in real operating conditions. In this paper, we present an experimental procedure for measuring in pulsed mode the small-signal impedance of a power device biased in any test conditions. The small-signal input impedance of a 650-V 20-A IGBT operated in short circuit has been measured as a function of the frequency. This input impedance has been used to extract the stability map of the IGBT in short circuit, which allows us to easily predict the test conditions where the IGBT becomes instable. The validity of this stability map has been confirmed by a large-signal time-domain characterization of the IGBT operated in short circuit. The proposed technique is very useful to design driving circuit able to avoid instable operations.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Avoiding Divergent Oscillation of a Cascode GaN Device Under High-Current
           Turn-Off Condition
    • Authors: Xiucheng Huang;Weijing Du;Fred C. Lee;Qiang Li;Wenli Zhang;
      Pages: 593 - 601
      Abstract: The cascode structure is widely used for high-voltage normally-on GaN devices. However, the capacitance mismatch between the high-voltage GaN device and the low-voltage normally-off Si MOSFET may induce several undesired features, such as Si MOSFET reaches avalanche during turn-off and the high-voltage GaN device loses zero-voltage switching turn-on condition internally during a soft-switching turn-on process in every switching cycle. This paper presents another issue associated with the capacitance mismatch in the cascode GaN devices. Divergent oscillation could occur at high-current turn-off condition and, eventually, destroys the device. The intrinsic reason of this phenomenon is analyzed in detail in this paper. A simple solution is proposed by adding an additional capacitor whose position is critical and should be optimized. Experimental results validate the theoretical analysis and show that the proposed method improves device performance significantly under high-current turn-off condition.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Investigation and Suppression of Current Zero Crossing Phenomenon for a
           Semicontrolled Open-Winding PMSG System
    • Authors: Heng Nian;Yijie Zhou;
      Pages: 602 - 612
      Abstract: The semicontrolled open-winding PMSG system has been widely investigated due to its simplified topology and easy control implementation. Nevertheless, compared with the conventional controllable converter structure, the current zero crossing phenomenon will last a longer time in the semicontrolled configuration, which is determined by the phase displacement between voltage and current. Since a long current zero crossing duration will lead to voltage pulse disturbance, serious electromagnetic interference, and output power fluctuation, it is necessary to reduce the zero crossing duration to improve the open-winding PMSG performance. This paper gives a detailed analysis on the zero crossing phenomenon of the semicontrolled open-winding PMSG system in the 3-D space vector modulation perspective. Meanwhile, a third harmonic injection method is suggested to reduce the zero crossing duration. It is also demonstrated that the torque and power pulsation are effectively improved, while the zero-sequence current amplitude does not increase. A proportional resonant controller is used to regulate the desired zero-sequence current. The proposed method is validated in a 1-kW semicontrolled open-winding PMSG experimental system with $i_{d} = 0$ control method.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Mathematic Analysis of Omnidirectional Wireless Power Transfer—Part-II
           Three-Dimensional Systems
    • Authors: Deyan Lin;Cheng Zhang;S. Y. Ron Hui;
      Pages: 613 - 624
      Abstract: Part-II of this paper focuses on the mathematical analysis of the 3-D omnidirectional wireless power transfer (WPT) and also addresses the general principle of load detection. It provides the mathematical forms of distributions of the input power vector and output power vector, and demonstrates that the geometry of such 3-D distributed space follows the revolution of the Lemniscate of Bernoulli along its longitudinal axis. It provides the mathematical proof that the direction of energy transfer for the maximum energy efficiency is always in line with that of the maximum load power path in the 3-D space. Experimental verification is included to confirm the 3-D omnidirectional WPT theory.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Mathematical Analysis of Omnidirectional Wireless Power Transfer—Part-I:
           Two-Dimensional Systems
    • Authors: Deyan Lin;Cheng Zhang;S. Y. Ron Hui;
      Pages: 625 - 633
      Abstract: This two-part paper aims at providing the basic mathematical theory of omnidirectional wireless power transfer (WPT). Based on current vector control, the magnetic field vector can be generated and pointed at any direction, thus achieving genuine omnidirectional wireless power flow. Part-I of this paper contains the mathematical analysis of the two-dimensional (2-D) system. The 2-D analysis shows that the total input power and the system energy efficiency of the WPT system can be expressed as functions of the angle of the input magnetic field vector. These functions follow the Lemniscates of Bernoulli on the 2-D plane. The directional nature of such curves provides the crucial information of the locations of the receivers so that the wireless power can theoretically be directed to the loads efficiently. The 2-D theory is presented here with the support of experimental verification. Understanding the 2-D omnidirectional WPT theory would make it relatively easy to appreciate the three dimensional one reported in Part II.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Fast Tracking Electrosurgical Generator Using Two-Rail Multiphase Buck
           Converter With GaN Switches
    • Authors: Scott Jensen;Dragan Maksimovic;
      Pages: 634 - 641
      Abstract: Electrosurgery involves the use of high-frequency (typically 100–500 kHz) alternating current to elicit a clinical response in tissue (e.g., cutting or cauterization) using a plasma arc. Standard electrosurgical generators (ESGs) are based on resonant inverters, which constrain the output frequency and waveshape. This paper describes a fast tracking ESG capable of shaping the output ac waveform over a range of frequencies, thus providing improved flexibility and control in electrosurgery applications. The proposed fast tracking ESG is based on a two-rail multiphase buck topology using GaN switches. Experimental results are given for a four-phase ESG prototype operating from $pm$250 V with 2-MHz per-phase switching frequency, capable of providing up to 50 W to an arc modeled as a 300–4000 Ω load.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Self-Correction of Commutation Point for High-Speed Sensorless BLDC Motor
           With Low Inductance and Nonideal Back EMF
    • Authors: Haitao Li;Shiqiang Zheng;Hongliang Ren;
      Pages: 642 - 651
      Abstract: This paper presents a novel self-correction method of commutation point for high-speed sensorless brushless dc motors with low inductance and nonideal back electromotive force (EMF) in order to achieve low steady-state loss of magnetically suspended control moment gyro. The commutation point before correction is obtained by detecting the phase of EMF zero-crossing point and then delaying 30 electrical degrees. Since the speed variation is small between adjacent commutation points, the difference of the nonenergized phase's terminal voltage between the beginning and the end of commutation is mainly related to the commutation error. A novel control method based on model-free adaptive control is proposed, and the delay degree is corrected by the controller in real time. Both the simulation and experimental results show that the proposed correction method can achieve ideal commutation effect within the entire operating speed range.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Discrete-Time Tool for Stability Analysis of DC Power Electronics-Based
           Cascaded Systems
    • Authors: Mehdi Karbalaye Zadeh;Roghayeh Gavagsaz-Ghoachani;Jean-Philippe Martin;Serge Pierfederici;Babak Nahid-Mobarakeh;Marta Molinas;
      Pages: 652 - 667
      Abstract: DC distribution power systems are vulnerable to instability because of the destabilizing effect of converter-controlled constant power loads (CPLs) and input filters. Standard stability analysis tools based on averaging linearization techniques can be used only when the switching frequency of the converter is significantly higher than the cutoff frequency of the filter. However, dc distribution systems with a reduced size filter, and consequently a high cutoff frequency, are common in transportation applications. Conventional methods fail to detect instabilities in the system because they do not take into account the switching effect. To overcome this drawback, this paper proposes a discrete-time method to analyze the stability of dc distribution systems. This model is applied here to a dc power system with a CPL. The switching effects and the nonlinearities of the system model are taken into account with a simple discretization approach. The proposed method is able to predict the dynamic properties of the system, such as slow-scale and fast-scale instabilities. An active stabilizer is also included in the system model in order to extend the stability margin of the system. Finally, these observations are validated experimentally on a laboratory test bench.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • A Fixed-Frequency Sliding Mode Controller for a Boost-Inverter-Based
           Battery-Supercapacitor Hybrid Energy Storage System
    • Authors: Damith Buddika Wickramasinghe Abeywardana;Branislav Hredzak;Vassilios G. Agelidis;
      Pages: 668 - 680
      Abstract: The boost-inverter-based battery-supercapacitor hybrid energy storage systems (HESSs) are a popular choice for the battery lifetime extension and system power enhancement. Various sliding mode (SM) controllers have been used to control the boost inverter topology in the literature. However, the traditional SM controllers for the boost inverter topology operate with a high and variable switching frequency which increases the power losses and system components design complexity. This can be alleviated by a pulse width modulation (PWM)-based fixed-frequency SM controller proposed in this paper. The SM controller is implemented using variable amplitude PWM carrier signals generated using the output capacitor voltage and inductor current measurements, thus eliminating the requirement of the output capacitor currents measurement. The battery-connected inductor reference currents for the SM controller are generated by a supercapacitor energy controller which is responsible for the HESS power allocation. First, the theoretical aspects of the SM controller, the operation and parameter selection of the supercapacitor energy controller, and the supercapacitor sizing for the HESS are discussed in the paper. Then, the proposed control system is experimentally verified, and it is shown that the HESS is able to satisfy the HESS output power requirements, while allocating the ripple current and the fast power fluctuations to the supercapacitor while maintaining operation of the supercapacitor within predefined voltage limits. The main advantage of the proposed SM controller, as compared with the traditional double-loop control method, is in eliminating possible DC current injection into the grid when the equivalent series resistance values of the boost inductors become unequal due to the tolerances and temperature variations.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Reliability Improvement Approach Based on Flatness Control of
           Parallel-Connected Inverters
    • Authors: Ahmed Shahin;Hassan Moussa;Ivano Forrisi;Jean-Philippe Martin;Babak Nahid-Mobarakeh;Serge Pierfederici;
      Pages: 681 - 692
      Abstract: In this paper, a global study in terms of control architecture is applied to parallel voltage-source inverters. Parallelism of inverters represents very interesting advantages for the industrial applications to meet the high-power requirements, and it is possible to apply maintenance during the operation without interruptible operation. The main objective of this paper is to guarantee a reliable operation of the parallel inverters system during healthy and faulty conditions due to full disconnection of any inverter. Special precautions are recommended to avoid the negative effects of the circulating currents, which are caused essentially by the asynchronous pulse width modulation or existence of dispersion of the system component characteristics. To deal with this crucial problem, one-loop flatness-based control is proposed to the control of N parallel inverters and allows obtaining low total harmonic distortion. The proposed control uses the advantages of the flatness to ensure high power quality at the point of common coupling and equal currents distribution between the parallel inverters and minimize the impact of a full disconnection of any inverter on the performance. The proposed algorithm is theoretically analyzed and validated experimentally.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • DC Power-Line Communication Based on Power/Signal Dual Modulation in Phase
           Shift Full-Bridge Converters
    • Authors: Jin Du;Jiande Wu;Ruichi Wang;Zhengyu Lin;Xiangning He;
      Pages: 693 - 702
      Abstract: For intelligent dc distributed power systems (DC-DPSs), data communication plays a vital role in system control and device monitoring. To achieve communication in a cost-effective way, power/signal dual modulation (PSDM), a method that integrates data transmission with power conversion, can be utilized. In this paper, an improved PSDM method using phase shift full-bridge (PSFB) converter is proposed. This method introduces a phase control-based freedom in the conventional PSFB control loop to realize communication using the same power conversion circuit. In this way, decoupled data modulation and power conversion are realized without extra wiring and coupling units, and thus, the system structure is simplified. More importantly, the signal intensity can be regulated by the proposed perturbation depth, and so this method can adapt to different operating conditions. Application of the proposed method to a DC-DPS composed of several PSFB converters is discussed. A 2kW prototype system with an embedded 5 kbps communication link has been implemented, and the effectiveness of the method is verified by experimental results.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • A Three-Level Space Vector Modulation Scheme for Paralleled Converters to
           Reduce Circulating Current and Common-Mode Voltage
    • Authors: Zhongyi Quan;Yun Wei Li;
      Pages: 703 - 714
      Abstract: For high-power applications, paralleling converters is a popular approach to increase the power capacity of the system. Circulating current has been a major concern for the implementation of paralleled converters. This paper proposes a three-level space vector modulation (SVM) scheme for a system with two paralleled voltage-source converters (VSCs) with common-mode inductor (CMI) or single-phase inductors. The proposed scheme aims to reduce the zero-sequence circulating current (ZSCC) and the magnitude of common-mode voltage (CMV) of the system simultaneously. The ZSCC patterns with respect to modulation schemes are first analyzed to provide a clear understanding of the generation of ZSCC. Based on the analysis, the proposed three-level modulation scheme is introduced. Furthermore, performance regarding the ZSCC peak value, impact on the common-mode current (CMC), CMI scaling analysis, and switching losses are analyzed and compared with the existing methods. The proposed method has been verified in both simulation and experiment.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Asymmetric Interleaving in Low-Voltage CMOS Power Management With Multiple
           Supply Rails
    • Authors: Marcel Schuck;Aaron D. Ho;Robert C. N. Pilawa-Podgurski;
      Pages: 715 - 722
      Abstract: This paper presents a technique for reducing the input current ripple on multiphase power converters that provide multiple heterogeneous power supply rails, such as those present in portable electronics and computers. Through asymmetric interleaving of individual phases, the input current ripple can be reduced compared to conventional interleaving. The technique is derived based on an analytic description of the relevant current waveforms. Practical requirements of a digital control implementation of the proposed technique are analyzed, and its possible performance improvement is quantified through simulations and experimental results. With the proposed technique, close to a 3x reduction in input current ripple, compared to conventional methods, is demonstrated using an experimental prototype comprising a microcontroller that controls a multiphase 180 nm CMOS power management IC.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Distributed Control and Redundant Technique to Achieve Superior
           Reliability for Fully Modular Input-Series-Output-Parallel Inverter System
    • Authors: Tianzhi Fang;Le Shen;Wei He;Xinbo Ruan;
      Pages: 723 - 735
      Abstract: Input-series-output-parallel (ISOP) inverter system is very suitable for high input voltage and large output current power conversion applications. One of many merits of this assembly system lies in that its characteristic of multimodule series–parallel combination can significantly improve the reliability of the operation. To address this point, redundancy should be realized for the whole system. However, the existing methods for the ISOP inverter system all belong to centralized control, which restricts the modularity of the system. From the above perspective, this paper proposes a new scheme to achieve both power balance and distributed configuration according to the conception of compound control. Also, the relationship of control loops is analyzed and the design procedure of them is given. Based on the fully modular system actualized by the distributed control, the hot-swap technique is then raised to get a redundant system with superior reliability. Here, the way of bypassing other than cutting off is adopted to fulfill withdrawal of the faulty module from the system due to series connection at the input terminal. In addition, the detailed timing sequence of system operation is provided to ensure the smooth transition during the hot-plugging transient. Finally, a three-module prototype is built and the experimental results validate the effectiveness of the presented strategy.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • A Multifunctional and Wireless Droop Control for Distributed Energy
           Storage Units in Islanded AC Microgrid Applications
    • Authors: Xiaofeng Sun;Yancong Hao;Qingfeng Wu;Xiaoqiang Guo;Baocheng Wang;
      Pages: 736 - 751
      Abstract: A multifunctional and wireless droop control method for distributed energy storage units (DESUs) in ac microgrids is presented in this paper. This paper achieves the state-of-charge (SoC) balancing by employing the SoC-based P-f droop control method locally for the purpose to prolong the service life of DESUs and effectively utilizing the available capability of the DESUs. Besides, inspired by the conventional P-f droop control, a $int Qdt - V$ droop control is proposed in this paper to eliminate the reactive power sharing errors. The $int {Qdt - V}$ droop control is realized by reducing the voltage proportional to the integration of the reactive power instead of the reactive power itself. Meanwhile, the voltage compensation term which is proportional to the integration of the accurately shared active power is added to this method in order to restore the voltage to the acceptable range. The control strategy is straightforward to implement and does not require communication links as well as the gain scheduling. This paper also presents the analysis of the corresponding small-signal stability of the proposed droop control method. Simulation and experimental results are provided to validate the feasibility and effectiveness of the proposed approach.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Model Predictive Control of Capacitor Voltage Balancing for Cascaded
           Modular DC–DC Converters
    • Authors: Qiang Wei;Bin Wu;Dewei Xu;Navid Reza Zargari;
      Pages: 752 - 761
      Abstract: Input-series output-series (ISOS) modular dc–dc converters are suitable for applications involving high input and output voltages. Input voltage sharing (IVS) and output voltage sharing (OVS) of the constituent modules must be guaranteed for an ISOS system. A duty cycle-based model predictive control (DC-MPC) scheme is proposed in this paper to achieve IVS and OVS for an ISOS system. The employed switching frequency in the DC-MPC scheme is fixed; duty cycles are optimized and then determined by minimizing a cost function, which is derived from an ISOS system aimed at achieving IVS and OVS. IVS and OVS can, therefore, be obtained by employing the optimized duty cycle within each sampling period. In addition, challenges and disadvantages of directly using traditional MPC to achieve IVS and OVS is briefly discussed, while the proposed DC-MPC can effectively avoid them. Compared with the existing proportional integral-based schemes in the literature, the proposed DC-MPC is better for IVS and OVS because it is a very simple and intuitive approach with lower cost and higher overall dynamic performance. Simulation and experiments are conducted to verify that the proposed DC-MPC scheme works well during both steady and transient states.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • A Time Delay Compensation Method Based on Area Equivalence For Active
           Damping of an LCL -Type Converter
    • Authors: Chen Chen;Jian Xiong;Zhiqiang Wan;Ji Lei;Kai Zhang;
      Pages: 762 - 772
      Abstract: Control of the LCL-type three-phase grid-connected converter is difficult due to high resonance peak of the LCL filter. Active damping is the state-of-the-art solution to this problem, but the damping performance will be affected by the inherent time delay of digital control, especially for high-power low switching frequency applications. Based on a discrete-time stability analysis of an LCL-type converter with capacitor-current-feedback active damping, a simple and effective time delay compensation method, which is based on area equalization concept, is proposed. The method can reduce the negative impact of the computation delay significantly. It has the potential to serve as a general solution to time delay compensation of a digitally controlled PWM converter. The validity of the proposed method is proved by experimental results.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Three-Vector-Based Low-Complexity Model Predictive Direct Power Control
           Strategy for Doubly Fed Induction Generators
    • Authors: Xiaohe Wang;Dan Sun;
      Pages: 773 - 782
      Abstract: This paper proposes a three-vector-based low-complexity model predictive direct power control (LC-MPDPC) strategy for doubly fed induction generators (DFIGs) in wind energy applications. Previous studies have applied one- and two-vector-based LC-MPDPC strategies for ac/dc converters with a satisfactory control performance. In this paper, an elaborated analysis of the DFIG mathematical model is made and then the feasibility of one- and two-vector-based LC-MPDPC strategies for DFIG are analyzed. However, using these approaches, the steady-state errors cannot be eliminated completely. Thus, a three-vector-based LC-MPDPC is further proposed to eliminate the power error. Both simulation and experimental results indicate that the proposed three-vector-based LC-MPDPC can significantly improve the steady-state performance and achieve an error-free control. In addition, its dynamic performance remains satisfactory compared with one- and two-vector-based LC-MPDPC.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Dynamic Optimum Dead Time in Piezoelectric Transformer-Based Switch-Mode
           Power Supplies
    • Authors: Marzieh Ekhtiari;Thomas Andersen;Michael A. E. Andersen;Zhe Zhang;
      Pages: 783 - 793
      Abstract: Soft switching is required to attain high efficiency in high-frequency power converters. Piezoelectric-transformer-based converters can benefit from soft switching in terms of significantly diminished switching losses and stresses. Adequate dead time is needed in order to deliver sufficient energy to charge and discharge the input capacitance of piezoelectric transformers in order to achieve zero-voltage switching. This paper proposes a method for detecting the optimum dead time in piezoelectric transformer-based switch-mode power supplies. The provision of sufficient dead time in every cycle of the switching period results in the quick start-up of resonant current inside the transformer. The new method is implemented by dynamically detecting the optimum dead time for each resonant cycle and results in reduced energy loss and, consequently, increased efficiency in the converter during initialization time and steady-state operation. The theory of optimum dead time operation is also discussed in this paper. Experimental results and simulation are provided to show the implementation of the concept.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Real-Time Model-Based Estimation of SOC and SOH for Energy Storage Systems
    • Authors: Mario Cacciato;Giovanni Nobile;Giuseppe Scarcella;Giacomo Scelba;
      Pages: 794 - 803
      Abstract: To obtain a full exploitation of battery potential in energy storage applications, an accurate modeling of electrochemical batteries is needed. In real terms, an accurate knowledge of state of charge (SOC) and state of health (SOH) of the battery pack is needed to allow a precise design of the control algorithms for energy storage systems (ESSs). Initially, a review of effective methods for SOC and SOH assessment has been performed with the aim to analyze pros and cons of standard methods. Then, as the tradeoff between accuracy and complexity of the model is the major concern, a novel technique for SOC and SOH estimation has been proposed. It is based on the development of a battery circuit model and on a procedure for setting the model parameters. Such a procedure performs a real-time comparison between measured and calculated values of the battery voltage while a PI-based observer is used to provide the SOC and SOH actual values. This ensures a good accuracy in a wide range of operating conditions. Moreover, a simple start-up identification process is required based on battery data-sheet exploitation. Because of the low computational burden of the whole algorithm, it can be easily implemented in low-cost control units. An experimental comparison between SOC and SOH estimation performed by suggested and standard methods is able to confirm the consistency of the proposed approach.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • A Dual-Level Hysteresis Current Control for One Five-Leg VSI to Control
           Two PMSMs
    • Authors: Wei Wang;Jinghao Zhang;Ming Cheng;
      Pages: 804 - 814
      Abstract: A dual-level hysteresis current control (DHCC) is proposed for the five-leg drive system, in which two same three-phase permanent-magnet synchronous machines (PMSMs) are controlled by one five-leg voltage-source inverter. To overcome the coupling of the two PMSMs, the master–slave selection principle is introduced. The coupling phase with the larger absolute value of the phase current error is determined as the master coupling phase and the leg-switch-state of the common leg is set as the phase-switch-state of the master coupling phase. On the other hand, the phase-switch-states of four individual phases are directly assigned to the four individual legs, respectively. The executing process of DHCC does not require any machine parameters, which enhances the system robustness. The effectiveness of DHCC is verified by experimental results.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Impact of Switching Harmonics on Capacitor Cells Balancing in
           Phase-Shifted PWM-Based Cascaded H-Bridge STATCOM
    • Authors: Ehsan Behrouzian;Massimo Bongiorno;Remus Teodorescu;
      Pages: 815 - 824
      Abstract: The purpose of this paper is to investigate the impact of switching harmonics on the instantaneous power distribution in the cells of a cascaded H-bridge-based STATCOM when using phase-shifted pulse width modulation. The case of high- and low-switching frequency for the converter cells is investigated and the interaction between voltage and current harmonics is analyzed. It is shown that in both cases, this interaction results in an uneven power distribution among the cells in the same phase leg, leading to drifting of the dc-capacitor voltages and thereby the need for proper stabilization control loops. It is also shown that the selected frequency modulation ratio affects the active power distribution among the cells. In particular, the selection of a noninteger frequency modulation ratio helps in providing a more uniform power distribution among cells of the same phase leg, thus contributing to the capacitors balancing. A methodology for optimal selection of the frequency modulation ratio is given. Theoretical conclusions are validated through simulation and experimental results.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • A Method for the Suppression of Fluctuations in the Neutral-Point
           Potential of a Three-Level NPC Inverter With a Capacitor-Voltage Loop
    • Authors: Yun Zhang;Jing Li;Xinmin Li;Yanfei Cao;Mark Sumner;Changliang Xia;
      Pages: 825 - 836
      Abstract: This paper investigates the problem of fluctuation of the neutral-point potential (NPP) in a three-level NPC inverter with a capacitor-voltage loop. The phase pulse width duty cycle disturbance pulse width modulation (PWM) method is proposed to suppress the NPP fluctuation efficiently. Based on the basic carrier-based phase-disposition PWM method, the average pulse neutral-point current model is established. Then, the frequency, amplitude, and equivalent initial phase of the NPP fluctuation are analyzed based on the current model. According to the alternating error of the dc-link capacitor voltages, a capacitor-voltage loop with a quasi-proportional resonant (PR) controller is presented. The control variable, which varies with the modulation index, phase current, load power factor, etc., can be obtained from the quasi-PR controller. Finally, an experimental three-level NPC inverter is described and the validity and feasibility of the proposed method are verified by experimental results.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Design and Analysis of a Conductance Compensator for Keeping Constant
           Bandwidth and Output Impedance in Average Current Mode Control
    • Authors: Ming Fu;Donglai Zhang;Tiecai Li;
      Pages: 837 - 848
      Abstract: Take the case of parallel modules in battery discharging regulator of power conditioning unit, which is based on Weinberg topology, a conductance compensator used in average current mode control is proposed in this paper, which could ensure constant loop bandwidth and output impedance when the number of operating parallel modules changes. The design principle of conductance compensator is shown as that the total conductance coefficient keeps constant when the number of operating parallel modules changes. Besides, a circuit of the conductance compensator, and the timing between the regulation of conductance compensator and ON/OFF of parallel modules, as well as the frequency-domain constraints of each function part in outer voltage control loop, are also illustrated. Additionally, measurements of the loop characteristic and output impedance of regulated power bus with different numbers of operating parallel modules, as well as the voltage ripple and current waveforms at the ON/OFF moment of parallel modules (four parallel modules in total), have been carried out, validating the design purpose of the proposed conductance compensator.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Synchronous Double-Pumping Technique for Integrated Current-Mode PWM
           DC–DC Converters Demand on Fast-Transient Response
    • Authors: Kuan-I Wu;Bor-Tsang Hwang;Charlie Chung-Ping Chen;
      Pages: 849 - 865
      Abstract: While the fast transient techniques have been extensively investigated, the research aiming at current-mode pulse width modulation (PWM) converters is relatively unexplored. This paper presents a synchronous double-pumping (SDP) technique for current-mode PWM dc–dc converters to achieve fast-transient response between different load conditions. The advantages and limitations of the existing conventional techniques are discussed and analyzed. With the proposed SDP technique, a nearly optimized recovery time speedup and voltage drop minimization for every different conventional current-mode converters can be obtained. The prototype chip was fabricated using a TSMC 0.35-μm CMOS process occupies the area of 2.242 mm2 including all bonding pads and ESD protection circuits. The output voltage ripple is measured about 15 mV in peak-to-peak value. The recovery time is 2.4 and 2.6 μs, respectively, in response to the 400-mA step-up and step-down load changes. Those are improved by a factor of 8.33 and 8.23, respectively.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Analysis of Bidirectional Piezoelectric-Based Converters for Zero-Voltage
           Switching Operation
    • Authors: Marzieh Ekhtiari;Zhe Zhang;Michael A. E. Andersen;
      Pages: 866 - 877
      Abstract: This paper deals with a thorough analysis of zero-voltage switching, especially for bidirectional inductorless piezoelectric transformer-based switch-mode power supplies with a half-bridge topology. Practically, obtaining zero-voltage switching for all of the switches in a bidirectional piezoelectric power converter is a difficult task. However, the analysis in this paper will be convenient for overcoming this challenge. The analysis defines the zero-voltage region indicating the operating points whether or not soft switching can be met over the switching frequency and load range. For the first time, a comprehensive analysis is provided, which can be used as a design guideline for applying control techniques in order to drive switches in piezoelectric transformer-based converters. This study further conveys the proposed method to the region where all the switches can obtain soft switching. Moreover, the analysis can be applied to other types of resonant converters with or without piezoelectric transformers. Experimental and simulation results are provided verifying the performed analysis.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
  • Feedback Control Strategy to Eliminate the Input Current Harmonics of
           Matrix Converter Under Unbalanced Input Voltages
    • Authors: Jiaxing Lei;Bo Zhou;Jinliang Bian;Jiadan Wei;Yiqi Zhu;Jiang Yu;Yang Yang;
      Pages: 878 - 888
      Abstract: It is generally considered that feedback control of input currents in the matrix converter (MC) is hard to be realized due to the coupling of input control and output control, which reduces the degree of freedom and robustness. Moreover, under unbalanced input voltages, the coupling also results in severe distortion of input currents when the commonly used feedforward compensation control method with fixed input power factor is adopted. To address these two issues, this paper proposes a feedback control strategy on the input side of MC. This strategy is based on a control method which can modify input reference currents. The input control strategy is embedded into the output control strategy and thus is the inner loop of the system control. The input-side controllers can be designed to achieve expected input control objectives and maintain the output performance at the same time. On this basis, resonant controllers are applied to regulate input currents and instantaneous active power, so as to directly eliminate the input current harmonics and meanwhile ensure the load absorbing constant active power under unbalanced input voltages. The validity and feasibility of the proposed strategy are verified by the simulation and experimental results.
      PubDate: Jan. 2017
      Issue No: Vol. 32, No. 1 (2017)
School of Mathematical and Computer Sciences
Heriot-Watt University
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