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  Subjects -> ELECTRONICS (Total: 188 journals)
Showing 1 - 200 of 277 Journals sorted alphabetically
Acta Electronica Malaysia     Open Access  
Advances in Electrical and Electronic Engineering     Open Access   (Followers: 7)
Advances in Electronics     Open Access   (Followers: 90)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Power Electronics     Open Access   (Followers: 38)
Advancing Microelectronics     Hybrid Journal  
Aerospace and Electronic Systems, IEEE Transactions on     Hybrid Journal   (Followers: 336)
American Journal of Electrical and Electronic Engineering     Open Access   (Followers: 26)
Annals of Telecommunications     Hybrid Journal   (Followers: 9)
APSIPA Transactions on Signal and Information Processing     Open Access   (Followers: 9)
Archives of Electrical Engineering     Open Access   (Followers: 14)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 8)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 30)
Bioelectronics in Medicine     Hybrid Journal  
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 20)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 38)
Biomedical Instrumentation & Technology     Hybrid Journal   (Followers: 6)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 13)
BULLETIN of National Technical University of Ukraine. Series RADIOTECHNIQUE. RADIOAPPARATUS BUILDING     Open Access   (Followers: 1)
Bulletin of the Polish Academy of Sciences : Technical Sciences     Open Access   (Followers: 1)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 47)
China Communications     Full-text available via subscription   (Followers: 9)
Chinese Journal of Electronics     Hybrid Journal  
Circuits and Systems     Open Access   (Followers: 15)
Consumer Electronics Times     Open Access   (Followers: 5)
Control Systems     Hybrid Journal   (Followers: 293)
ECTI Transactions on Computer and Information Technology (ECTI-CIT)     Open Access  
ECTI Transactions on Electrical Engineering, Electronics, and Communications     Open Access  
Edu Elektrika Journal     Open Access   (Followers: 1)
Electrica     Open Access  
Electronic Design     Partially Free   (Followers: 117)
Electronic Markets     Hybrid Journal   (Followers: 7)
Electronic Materials Letters     Hybrid Journal   (Followers: 4)
Electronics     Open Access   (Followers: 97)
Electronics and Communications in Japan     Hybrid Journal   (Followers: 10)
Electronics For You     Partially Free   (Followers: 100)
Electronics Letters     Hybrid Journal   (Followers: 26)
Elkha : Jurnal Teknik Elektro     Open Access  
Embedded Systems Letters, IEEE     Hybrid Journal   (Followers: 55)
Energy Harvesting and Systems     Hybrid Journal   (Followers: 4)
Energy Storage Materials     Full-text available via subscription   (Followers: 3)
EPJ Quantum Technology     Open Access   (Followers: 1)
EURASIP Journal on Embedded Systems     Open Access   (Followers: 11)
Facta Universitatis, Series : Electronics and Energetics     Open Access  
Foundations and Trends® in Communications and Information Theory     Full-text available via subscription   (Followers: 6)
Foundations and Trends® in Signal Processing     Full-text available via subscription   (Followers: 10)
Frequenz     Hybrid Journal   (Followers: 1)
Frontiers of Optoelectronics     Hybrid Journal   (Followers: 1)
Geoscience and Remote Sensing, IEEE Transactions on     Hybrid Journal   (Followers: 205)
Haptics, IEEE Transactions on     Hybrid Journal   (Followers: 4)
IACR Transactions on Symmetric Cryptology     Open Access  
IEEE Antennas and Propagation Magazine     Hybrid Journal   (Followers: 99)
IEEE Antennas and Wireless Propagation Letters     Hybrid Journal   (Followers: 80)
IEEE Journal of Emerging and Selected Topics in Power Electronics     Hybrid Journal   (Followers: 49)
IEEE Journal of the Electron Devices Society     Open Access   (Followers: 9)
IEEE Journal on Exploratory Solid-State Computational Devices and Circuits     Hybrid Journal   (Followers: 1)
IEEE Power Electronics Magazine     Full-text available via subscription   (Followers: 72)
IEEE Transactions on Antennas and Propagation     Full-text available via subscription   (Followers: 71)
IEEE Transactions on Automatic Control     Hybrid Journal   (Followers: 58)
IEEE Transactions on Circuits and Systems for Video Technology     Hybrid Journal   (Followers: 26)
IEEE Transactions on Consumer Electronics     Hybrid Journal   (Followers: 42)
IEEE Transactions on Electron Devices     Hybrid Journal   (Followers: 19)
IEEE Transactions on Information Theory     Hybrid Journal   (Followers: 26)
IEEE Transactions on Power Electronics     Hybrid Journal   (Followers: 78)
IEEE Transactions on Signal and Information Processing over Networks     Full-text available via subscription   (Followers: 12)
IEICE - Transactions on Electronics     Full-text available via subscription   (Followers: 12)
IEICE - Transactions on Information and Systems     Full-text available via subscription   (Followers: 5)
IET Cyber-Physical Systems : Theory & Applications     Open Access   (Followers: 1)
IET Energy Systems Integration     Open Access  
IET Microwaves, Antennas & Propagation     Hybrid Journal   (Followers: 35)
IET Nanodielectrics     Open Access  
IET Power Electronics     Hybrid Journal   (Followers: 55)
IET Smart Grid     Open Access  
IET Wireless Sensor Systems     Hybrid Journal   (Followers: 18)
IETE Journal of Education     Open Access   (Followers: 4)
IETE Journal of Research     Open Access   (Followers: 11)
IETE Technical Review     Open Access   (Followers: 13)
IJEIS (Indonesian Journal of Electronics and Instrumentation Systems)     Open Access   (Followers: 3)
Industrial Electronics, IEEE Transactions on     Hybrid Journal   (Followers: 70)
Industrial Technology Research Journal Phranakhon Rajabhat University     Open Access  
Industry Applications, IEEE Transactions on     Hybrid Journal   (Followers: 35)
Informatik-Spektrum     Hybrid Journal   (Followers: 2)
Instabilities in Silicon Devices     Full-text available via subscription   (Followers: 1)
Intelligent Transportation Systems Magazine, IEEE     Full-text available via subscription   (Followers: 13)
International Journal of Advanced Research in Computer Science and Electronics Engineering     Open Access   (Followers: 18)
International Journal of Advances in Telecommunications, Electrotechnics, Signals and Systems     Open Access   (Followers: 11)
International Journal of Antennas and Propagation     Open Access   (Followers: 11)
International Journal of Applied Electronics in Physics & Robotics     Open Access   (Followers: 4)
International Journal of Computational Vision and Robotics     Hybrid Journal   (Followers: 6)
International Journal of Control     Hybrid Journal   (Followers: 11)
International Journal of Electronics     Hybrid Journal   (Followers: 7)
International Journal of Electronics and Telecommunications     Open Access   (Followers: 13)
International Journal of Granular Computing, Rough Sets and Intelligent Systems     Hybrid Journal   (Followers: 3)
International Journal of High Speed Electronics and Systems     Hybrid Journal  
International Journal of Hybrid Intelligence     Hybrid Journal  
International Journal of Image, Graphics and Signal Processing     Open Access   (Followers: 16)
International Journal of Microwave and Wireless Technologies     Hybrid Journal   (Followers: 10)
International Journal of Nanoscience     Hybrid Journal   (Followers: 1)
International Journal of Numerical Modelling: Electronic Networks, Devices and Fields     Hybrid Journal   (Followers: 4)
International Journal of Power Electronics     Hybrid Journal   (Followers: 25)
International Journal of Review in Electronics & Communication Engineering     Open Access   (Followers: 4)
International Journal of Sensors, Wireless Communications and Control     Hybrid Journal   (Followers: 10)
International Journal of Systems, Control and Communications     Hybrid Journal   (Followers: 4)
International Journal of Wireless and Microwave Technologies     Open Access   (Followers: 6)
International Transaction of Electrical and Computer Engineers System     Open Access   (Followers: 2)
JAREE (Journal on Advanced Research in Electrical Engineering)     Open Access  
Journal of Biosensors & Bioelectronics     Open Access   (Followers: 3)
Journal of Advanced Dielectrics     Open Access   (Followers: 1)
Journal of Artificial Intelligence     Open Access   (Followers: 11)
Journal of Circuits, Systems, and Computers     Hybrid Journal   (Followers: 4)
Journal of Computational Intelligence and Electronic Systems     Full-text available via subscription   (Followers: 1)
Journal of Electrical and Electronics Engineering Research     Open Access   (Followers: 32)
Journal of Electrical Bioimpedance     Open Access  
Journal of Electrical Bioimpedance     Open Access   (Followers: 2)
Journal of Electrical Engineering & Electronic Technology     Hybrid Journal   (Followers: 7)
Journal of Electrical, Electronics and Informatics     Open Access  
Journal of Electromagnetic Analysis and Applications     Open Access   (Followers: 8)
Journal of Electromagnetic Waves and Applications     Hybrid Journal   (Followers: 9)
Journal of Electronic Design Technology     Full-text available via subscription   (Followers: 6)
Journal of Electronics (China)     Hybrid Journal   (Followers: 5)
Journal of Energy Storage     Full-text available via subscription   (Followers: 4)
Journal of Engineered Fibers and Fabrics     Open Access   (Followers: 2)
Journal of Field Robotics     Hybrid Journal   (Followers: 3)
Journal of Guidance, Control, and Dynamics     Hybrid Journal   (Followers: 173)
Journal of Information and Telecommunication     Open Access   (Followers: 1)
Journal of Intelligent Procedures in Electrical Technology     Open Access   (Followers: 3)
Journal of Low Power Electronics     Full-text available via subscription   (Followers: 10)
Journal of Low Power Electronics and Applications     Open Access   (Followers: 10)
Journal of Microelectronics and Electronic Packaging     Hybrid Journal  
Journal of Microwave Power and Electromagnetic Energy     Hybrid Journal   (Followers: 3)
Journal of Microwaves, Optoelectronics and Electromagnetic Applications     Open Access   (Followers: 11)
Journal of Nuclear Cardiology     Hybrid Journal  
Journal of Optoelectronics Engineering     Open Access   (Followers: 4)
Journal of Physics B: Atomic, Molecular and Optical Physics     Hybrid Journal   (Followers: 29)
Journal of Power Electronics & Power Systems     Full-text available via subscription   (Followers: 11)
Journal of Semiconductors     Full-text available via subscription   (Followers: 5)
Journal of Sensors     Open Access   (Followers: 26)
Journal of Signal and Information Processing     Open Access   (Followers: 9)
Jurnal ELTIKOM : Jurnal Teknik Elektro, Teknologi Informasi dan Komputer     Open Access  
Jurnal Rekayasa Elektrika     Open Access  
Jurnal Teknik Elektro     Open Access  
Jurnal Teknologi Elektro     Open Access  
Kinetik : Game Technology, Information System, Computer Network, Computing, Electronics, and Control     Open Access  
Learning Technologies, IEEE Transactions on     Hybrid Journal   (Followers: 12)
Magnetics Letters, IEEE     Hybrid Journal   (Followers: 7)
Majalah Ilmiah Teknologi Elektro : Journal of Electrical Technology     Open Access   (Followers: 2)
Metrology and Measurement Systems     Open Access   (Followers: 6)
Microelectronics and Solid State Electronics     Open Access   (Followers: 27)
Nanotechnology Magazine, IEEE     Full-text available via subscription   (Followers: 41)
Nanotechnology, Science and Applications     Open Access   (Followers: 6)
Nature Electronics     Hybrid Journal   (Followers: 1)
Networks: an International Journal     Hybrid Journal   (Followers: 5)
Open Electrical & Electronic Engineering Journal     Open Access  
Open Journal of Antennas and Propagation     Open Access   (Followers: 9)
Optical Communications and Networking, IEEE/OSA Journal of     Full-text available via subscription   (Followers: 15)
Paladyn. Journal of Behavioral Robotics     Open Access   (Followers: 1)
Power Electronics and Drives     Open Access   (Followers: 2)
Problemy Peredachi Informatsii     Full-text available via subscription  
Progress in Quantum Electronics     Full-text available via subscription   (Followers: 7)
Pulse     Full-text available via subscription   (Followers: 5)
Radiophysics and Quantum Electronics     Hybrid Journal   (Followers: 2)
Recent Advances in Communications and Networking Technology     Hybrid Journal   (Followers: 3)
Recent Advances in Electrical & Electronic Engineering     Hybrid Journal   (Followers: 9)
Research & Reviews : Journal of Embedded System & Applications     Full-text available via subscription   (Followers: 5)
Revue Méditerranéenne des Télécommunications     Open Access  
Security and Communication Networks     Hybrid Journal   (Followers: 2)
Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of     Hybrid Journal   (Followers: 56)
Semiconductors and Semimetals     Full-text available via subscription   (Followers: 1)
Sensing and Imaging : An International Journal     Hybrid Journal   (Followers: 2)
Services Computing, IEEE Transactions on     Hybrid Journal   (Followers: 4)
Software Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 78)
Solid State Electronics Letters     Open Access  
Solid-State Circuits Magazine, IEEE     Hybrid Journal   (Followers: 13)
Solid-State Electronics     Hybrid Journal   (Followers: 9)
Superconductor Science and Technology     Hybrid Journal   (Followers: 3)
Synthesis Lectures on Power Electronics     Full-text available via subscription   (Followers: 3)
Technical Report Electronics and Computer Engineering     Open Access  
TELE     Open Access  
Telematique     Open Access  
TELKOMNIKA (Telecommunication, Computing, Electronics and Control)     Open Access   (Followers: 9)
Transactions on Electrical and Electronic Materials     Hybrid Journal  
Universal Journal of Electrical and Electronic Engineering     Open Access   (Followers: 6)
Ural Radio Engineering Journal     Open Access  
Visión Electrónica : algo más que un estado sólido     Open Access   (Followers: 1)
Wireless and Mobile Technologies     Open Access   (Followers: 6)
Wireless Power Transfer     Full-text available via subscription   (Followers: 4)
Women in Engineering Magazine, IEEE     Full-text available via subscription   (Followers: 11)
Електротехніка і Електромеханіка     Open Access  

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Similar Journals
Journal Cover
IEEE Transactions on Power Electronics
Journal Prestige (SJR): 2.215
Citation Impact (citeScore): 9
Number of Followers: 78  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0885-8993
Published by IEEE Homepage  [191 journals]
  • IEEE Power Electronics Society
    • PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • IEEE Power Electronics Society
    • PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Blank page
    • PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Direct Approach of Simultaneously Eliminating EMI-Critical Oscillations
           and Decreasing Switching Losses for Wide Bandgap Power Semiconductors
    • Authors: Lars Middelstaedt;Jianjing Wang;Bernard H. Stark;Andreas Lindemann;
      Pages: 10376 - 10380
      Abstract: Most power electronic circuits naturally suffer from undesirable oscillations, which increase circuit stress and electromagnetic interference. These oscillations can, for example, arise from commutation cell resonance, and are particularly problematic in fast-switching SiC and GaN circuits. Damping these oscillations by active gate driving has been previously proposed as an alternative to limiting the switching speed or further minimizing parasitic inductance. However, for active drivers with almost unlimited degrees of freedom in the choice of gate driving profiles, fast and efficient profile optimization techniques have yet to be developed. This letter analytically determines four key measurable indicators, which help to find optimal gate signal shaping settings for an active driver. These include the device voltage gradient, as well as the gradient and overshoot level at specific points in the transient current. This optimization strategy is tested by using it to find the optimal settings for a variable-resistance active gate driver in a 400V-GaN boost converter. Measurements of switching transients and radiated electromagnetic emissions show experimentally that the proposed strategy reduces noise and switching loss at the same time. Compared to slower nonactive driving, radiated electromagnetic emissions are down by 10 dB, and losses by 6%.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Nonlinear Control for Output Voltage Regulation of a Boost Converter With
           a Constant Power Load
    • Authors: Blanca Areli Martinez-Treviño;Abdelali El Aroudi;Angel Cid-Pastor;Luis Martinez-Salamero;
      Pages: 10381 - 10385
      Abstract: A nonlinear control strategy is proposed for the output voltage regulation in a boost converter that supplies a constant power load. State-feedback linearization is used to transform the nonlinear average dynamics of the inductor current in the converter into a linear average dynamics of the inductor current in a virtual mesh, which consists in the series connection of a voltage source, a resistor, and the converter inductor. In the virtual mesh, the resistor introduces damping to contribute to the system stability, while the voltage source indirectly regulates the output voltage. Conditions for the control parameters to ensure the system stability are given. The control can be implemented analogically, this requiring some linear circuits based on operational amplifiers, an analogue divider, and a pulsewidth modulator. Experimental results show a fast recovery and zero steady-state output voltage error in the response to large-signal disturbances in both input voltage and output power.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Single-Switch-Regulated Resonant WPT Receiver
    • Authors: Kerui Li;Siew-Chong Tan;Ron Shu Yuen Hui;
      Pages: 10386 - 10391
      Abstract: A single-switch-regulated wireless power transfer receiver is presented in this letter. Aiming at low-cost applications, the system involves only a single-switch class-E resonant rectifier, a frequency synchronization circuit, and a microcontroller. The number of power semiconductor devices required in this circuit is minimal. Only one active switch is used and no diode is required. As a single-switch solution, this simplifies circuit implementation, improves reliability, and lowers the hardware cost. The single-switch resonant rectifier provides a relatively constant quasi-sinusoidal voltage waveform to pick up the wireless power from the receiver coil. Due to the resonant nature of the rectifier, zero-voltage-switching (ZVS) turn on and turn off are achieved. The steady-state analysis and discussions on the component sizing and the control design are provided. A prototype is built and experimental works are performed to verify the features: achieving 93% efficiency single-switch ac–dc rectification (85% including the auxiliary circuit), −7.17-dB total-harmonic-distortion ac voltage waveform, ZVS turn on and turn off over wide load range, 0.4% output voltage regulation error, 79% cost reduction as compared with the Qi- compliant receivers, 2.5% overshoot/undershoot after load disturbances, and 1% overshoot after line disturbance.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Probability-Based Modeling and Analysis for PS-PWM in an MMC Distributed
           Control System With Sub-Module Asynchrony
    • Authors: Shunfeng Yang;Haiyu Wang;Haiyu Chen;Wensheng Song;Tao Wang;
      Pages: 10392 - 10397
      Abstract: Modular multilevel converters for high-voltage dc transmission applications normally adopt a distributed control system, where a large number of local controllers are employed, to manage considerable sub-modules (SMs) in the system. The manufacturing tolerance of crystal oscillators for local controllers introduces controller clock discrepancy and eventually leads to the asynchrony of triangular carriers implemented in individual SM for phase-shifted pulsewidth modulation scheme. Considering the tolerance of oscillators having a normal distribution, the deviation of the triangular carrier frequency is modeled based on the probability theory in this letter. The switching function model taking such asynchrony into account is proposed allowing quantitative analysis and evaluation of the switching harmonic contents. Good agreements of the harmonic contents have been achieved between the theoretical calculation and experimental results. The calculated switching harmonics can be used to determine the synchronization interval according to the system requirements.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A Trans-Inverse Coupled-Inductor Semi-SEPIC DC/DC Converter With Full
           Control Range
    • Authors: Ali Mostaan;Jing Yuan;Yam P. Siwakoti;Soroush Esmaeili;Frede Blaabjerg;
      Pages: 10398 - 10402
      Abstract: This letter proposes a single switch magnetically coupled dc–dc converter with a high voltage gain. The unique features of the converter are summarized as follows: 1) voltage gain of the converters is raised by lowering its magnetic turn ratio; 2) wide control range ($ 0< D< 1$); 3) continuous current from the source that makes it a suitable candidate for renewable energy applications; and 4) there is no dc current saturation in the core due to the presence of capacitor in the primary winding of the inductor. The feasibility of the proposed converter is studied in details supported by circuit analysis and simulation results. Furthermore, the proposed converter is analyzed and compared with other converters with similar features. Finally the superior performance of the circuit is validated experimentally.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Condition Monitoring for Submodule Capacitors in Modular Multilevel
    • Authors: Hanyu Wang;Huai Wang;Zhongxu Wang;Yi Zhang;Xuejun Pei;Yong Kang;
      Pages: 10403 - 10407
      Abstract: This letter proposes a method for the condition monitoring of submodule (SM) capacitors in modular multilevel converters (MMCs) without additional circuitry or computationally heavy algorithm. The proposed method leverages the discharging curve of SM capacitors in connection with the parallel bleeding resistors. It is independent of the MMC control and modulation schemes. Moreover, it potentially does not require thermal and load-related calibration for capacitor degradation monitoring. The principle, case study, and proof of concept of the proposed method are presented.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Condition Monitoring the Health Status of Forced Air Cooling System Using
           the Natural Frequency of Thermal Network
    • Authors: Jun Zhang;Xiong Du;Wenshan Xiao;Shuai Zheng;
      Pages: 10408 - 10413
      Abstract: The forced air cooling system plays an important role in the safe operation of power converters. Condition monitoring its health status can improve the reliability of power converter and reduce the cost of unscheduled maintenance due to over-heating. This letter proposed to use the natural frequency of thermal network as an indicator to monitor the aging process of cooling system. We show that the degradation of the cooling system can be monitored by detecting the variation of thermal network natural frequency. Experimental tests on a three-phase dc/ac converter with forced air cooling system are performed to verify the effectiveness of proposed method. This method is simple to implement and does not need to measure the power loss. Moreover, it enables the concurrent monitoring of multiple components in the cooling system.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A Continuous Rectangular-Wave Method for Junction Temperature Measurement
           of Light-Emitting Diodes
    • Authors: Ze-Hui Liu;Jia-En Huang;Yu-Lin Gao;Zi-Quan Guo;Yue Lin;Li-Hong Zhu;Zhong Chen;Yi-Jun Lu;
      Pages: 10414 - 10424
      Abstract: Junction temperature is an important parameter for evaluating thermal property of light-emitting diodes (LEDs). How to accurately measure the junction temperature still remains controversial. In this paper, we propose a continuous rectangular-wave method (CRWM) for measuring the junction temperature of LEDs. This method uses a continuous rectangular wave to drive LED under either voltage mode or current mode, and acquires the transient voltage response, i.e., the heating curve, by a high-definition oscilloscope at the rising edge of each cycle. Compared with the conventional forward voltage method (FVM), where a switch is necessary to transit the heating state to the sensing state and a transient cooling curve is usually acquired, the switch-free-periodic-acquisition CRWM avoids the acquisition time delay caused by switch and decreases charging/discharging effect of LEDs effectively with rising time of the rectangular wave less than 40 μs. Besides, periodic acquisition of the heating curve further enhances the signal-to-noise ratio. Comparative experiments by FVM, CRWM, and micro-thermocouple show coincidence and accuracy of CRWM with relative error less than 3% in current mode and 1.5% in voltage mode. COMSOL simulation is applied to verify the validity of CRWM and discuss the impact of rising time of the rectangular wave.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • An Analytical Correction to Dowell's Equation for Inductor and
           Transformer Winding Losses Using Cylindrical Coordinates
    • Authors: Daniel Whitman;Marian K. Kazimierczuk;
      Pages: 10425 - 10432
      Abstract: Analytical expressions that have been derived to calculate ac resistance and losses of magnetic devices at high frequencies have primarily used a one-dimensional approximation, and have used Cartesian coordinates or approximations that are equivalent to Cartesian coordinates. The result is Dowell's equation. This paper examines the effect of winding curvature on the losses relative to Dowell's equation by solving the problem completely in cylindrical coordinates. The error in Dowell's equation relative to a full cylindrical solution is found to be as great as 33% for some designs. A mathematical model is derived for the relative error between the two solutions, which can be used to assess the accuracy of Dowell's equation for a particular design, as well as a correction factor for Dowell's equation. The corrected Dowell's equation using the model is validated using finite-element analysis simulations as well as previously published experimental data. This paper is accompanied by Python codes to generate all data and figures used in the paper, a Python object that implements the derived mathematical model, and Lua scripts to run the finite-element simulations using FEMM.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A 2-D Magnetoinductive Wave Device for Freer Wireless Power Transfer
    • Authors: Fralett Suárez Sandoval;Saraí M. Torres Delgado;Ali Moazenzadeh;Ulrike Wallrabe;
      Pages: 10433 - 10445
      Abstract: In this paper, we present a wireless power transfer (WPT) system with a two-dimensional (2-D) magnetoinductive wave (MIW) device composed by two orthogonal sets of 1-D MIW devices woven together. The device is made by 112 double-spiral coils, a geometry that we have optimized to render a low attenuation propagation. This approach enables a charging area of 22 × 22 cm2 from which a receiver device can be supplied with energy with optimum efficiency from 32 different locations with the use of a single excitation port. We present a detailed optimization of the design and fabrication of the device. To describe the behavior of the device, we use a modeling method based on the impedance matrix that allows us to include all coupling interactions among the increased number of cells. With this method, we are able to find the optimal operating conditions like the location of the excitation and the coupling conditions of the receiver device. With the proposed 2-D MIW device, we can provide up to 5 W to a load of 5 $Omega$ located at the optimal axial separation. We corroborate our calculations with vector network analysis and dc output power measurements. Furthermore, we demonstrate the device supplying to distinct types of loads simultaneously. This paper is accompanied by a supplementary file showing the required MATLAB script and input files to calculate the mutual inductance between a receiver and the cells of the pad.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A 1-kV Input SiC LLC Converter With Split Resonant Tanks
           and Matrix Transformers
    • Authors: Xiaoyong Ren;Zhi-Wei Xu;Zhiliang Zhang;Haoran Li;Mingxie He;Jiachen Tang;Qianhong Chen;
      Pages: 10446 - 10457
      Abstract: A 1-kV input SiC LLC converter with the matrix planar transformers is proposed to achieve high efficiency and high power density. With fast switching speed 140 ns of SiC mosfets at 1-kV input voltage, high dv/dt of 11.8 kV/μs can cause large displacement current via the parasitic capacitance between the primary and secondary sides of high-frequency planar transformers. The displacement current via the interwinding capacitance can distort the resonant current seriously. This causes the control mosfets not to realize ZVS and induces high switching loss at 1 kV. An LLC topology with split resonant tanks is proposed for high input voltage applications. The resonant tank is split into two identical resonant tanks to provide symmetrical resonant current with the same impedance. Compared with the conventional LLC converters, the input and output current of the resonant tank is symmetrical, avoiding the current distortion. Therefore, all of the control mosfets can realize ZVS. The transformer interwinding capacitance modeling and a reduction solution are presented, which reduces the waveform distortion by 68%. Two SiC prototypes of 3 and 4 kW with an input of 1 kV and output of 32 and 48 V were built, respectively. The efficiency is 94.9% at full load at 300 kHz for a 3-kW module and 96.0% at full load for a 4-kW module. The power density is 3.87 kW/L (63.4 W/in3) and 4.11 kW/kg for the 4-kW module.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Balancing of Submodule Capacitor Voltage of Hybrid Modular Multilevel
           Converter Under DC-Bus Voltage Variation of HVDC System
    • Authors: Joon-Hee Lee;Jae-Jung Jung;Seung-Ki Sul;
      Pages: 10458 - 10470
      Abstract: A hybrid modular multilevel converter (MMC) consists of both half-bridge submodule (HBSM) and full-bridge submodule (FBSM) in each arm. It has several advantages over other MMC topologies, such as low system loss, reduced cost of the system, but still maintains fault ride-through capability against a solid dc-side fault. However, the hybrid MMC may have a difficulty of submodule (SM) voltage balancing under variation of its dc-bus voltage. Since the voltage unbalance of SMs results in SM capacitor overvoltage and low reliability of the system, the voltage of SMs, which can be also represented as energy of SMs, should be balanced at all time. In this paper, to extend the narrow adjustable range of dc-bus voltage due to the voltage/energy unbalance, new feedback and feedforward energy balancing controllers with revised sorting algorithm are proposed. The feedback control ensures the zero steady-state error, while the feedforward control provides fast dynamic response in the energy balancing control. By applying the proposed control scheme, the hybrid MMC can keep the voltage balance between HBSMs and FBSMs in wider range of dc-bus voltage. The full-scale computer simulation results and down-scale experimental results demonstrate the validity of the proposed control scheme.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • New Family of Boost Switched-Capacitor Seven-Level Inverters (BSC7LI)
    • Authors: Sze Sing Lee;Yeongsu Bak;Seok-Min Kim;Anto Joseph;Kyo-Beum Lee;
      Pages: 10471 - 10479
      Abstract: This paper proposes a new family of multilevel inverter topology that is able to generate seven voltage levels by utilizing one or two floating capacitors and 10 power switches. This novel boost switched-capacitor seven-level inverter possesses voltage boosting capability with an achievable maximum voltage level 1.5 times the input direct current (dc) voltage. The generation of higher output voltage does not incur high-voltage stress on any power switch in this topology, as the peak inverse voltages of all power switches do not exceed the input source voltage. In addition, capacitor voltage balancing is not essential since the floating capacitors are effectively balanced during the charging and discharging processes. Furthermore, the proposed topology eliminates the need for multiple isolated dc sources, and a single dc source is sufficient in both its single-phase and three-phase topologies. The operating principle and steady-state analysis of the proposed topology are elaborated. Experimental results from a single-phase prototype are then presented to verify the validity of the proposed topology.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A Reduced Switching Frequency Sorting Algorithm for Modular Multilevel
           Converter With Circulating Current Suppression Feature
    • Authors: Debdeep Samajdar;Tanmoy Bhattacharya;Saurav Dey;
      Pages: 10480 - 10491
      Abstract: One important characteristic of modular multilevel converter (MMC) is the existence of circulating current, which consists of a dc component and a series of undesirable even-order (predominantly second-order) harmonics. However, only the dc part of the circulating current is required for power balance, the ac harmonics are unwanted. These undesirable harmonics should be suppressed to reduce device stress and power losses. Most state-of-the-art circulating current suppression techniques employ separate controllers to generate the arm reference voltage for circulating current suppression. This paper proposes an alternate approach, eliminating the need of any additional control loop. Generation of undesirable circulating current is prevented inherently in the modulation stage. Reduced switching frequency sorting algorithm based modulation framework is employed to ensure reduced switching loss. Suitability of the proposed method is validated by experiments performed on a three-phase laboratory prototype of MMC. Steady state and transient operation of the MMC in grid-connected condition is studied.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A Novel Seven-Level Active Neutral-Point-Clamped Converter With Reduced
           Active Switching Devices and DC-Link Voltage
    • Authors: Yam P. Siwakoti;Akshay Mahajan;Daniel J. Rogers;Frede Blaabjerg;
      Pages: 10492 - 10508
      Abstract: This paper presents a novel seven-level inverter topology for medium-voltage high-power applications. It consists of eight active switches and two inner flying capacitor (FC) units forming a similar structure as in a conventional active neutral-point-clamped (ANPC) inverter. This unique arrangement reduces the number of active and passive components. A simple modulation technique reduces cost and complexity in the control system design without compromising reactive power capability. In addition, compared to major conventional seven-level inverter topologies, such as the neutral point clamped, FC, cascaded H-bridge, and ANPC topologies, the new topology reduces the dc-link voltage requirement by 50%. This recued dc-link voltage makes the new topology appealing for various industrial applications. Experimental results from a 2.2-kVA prototype are presented to support the theoretical analysis presented in this paper. The prototype demonstrates a conversion efficiency of around 97.2% ± 1% for a wide load range.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A New Control Architecture With Spatial Comb Filter and Spatial Repetitive
           Controller for Circulating Current Harmonics Elimination in a
           Droop-Regulated Modular Multilevel Converter for Wind Farm Application
    • Authors: Sandeep Kolluri;Naga Brahmendra Yadav Gorla;Rajesh Sapkota;Sanjib Kumar Panda;
      Pages: 10509 - 10523
      Abstract: Circulating current control is one of the critical issues in modular multilevel converters (MMCs). When a frequency-droop-regulated MMC is used to integrate an offshore wind farm into an high-voltage dc transmission system, the variation in its operating ac line frequency induces a change in circulating current harmonic frequencies. Hence, the conventional circulating current controllers, such as proportional-resonant or repetitive controller, which are tuned to a specific frequency, fail to alleviate the circulating current harmonics. In this paper, a new control architecture comprising of a spatial comb filter (SCF) and a spatial repetitive controller (SRC) is proposed to effectively attenuate the even-order harmonics in the circulating current independent of the operating ac line frequency of the MMC. The proposed controller incorporates the phase sampling technique to achieve the dynamic change in the sampling frequency, which is the key to strong periodic disturbance rejection capability of the SCF and SRC even under variable frequency operation. A system level simulation model has been developed on PLECS simulation software to demonstrate the performance of the proposed control architecture. In addition, a scaled-down laboratory prototype of a 1-kW, 400-V, five-level single-phase MMC is developed and the experimental results are presented to substantiate the performance of the proposed control scheme.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Research on 1100-kV/5500-A Ultra-High Voltage Thyristor Valve Key
           Technology and Its Application
    • Authors: Ruifeng Gou;
      Pages: 10524 - 10533
      Abstract: As direct current (dc) voltage and current increase to 1100 kV and 5455 A, respectively, ultra-high voltage (UHV) thyristor valve will be in complicated electric, magnetic, thermal, and mechanical environments. First, we analyzed the internal mechanism of damping characteristics and accurate internal relationship between electromagnetic transients of damping circuit and proposed its determination method. We developed a correction function of reverse recovery charge for thyristor valve under different working conditions, subsequently. Based on that, we proposed a calculation method for thyristor junction temperature and constructed a model for analyzing thyristor stress. Dielectric test was performed using dummy load and a method was proposed for determining dummy load parameters. The designed UHV thyristor valve successfully passed the full set of tests according to IEC60700-1 standards. Additionally, it has been applied in the Changji-Guquan HVdc project, which possesses the highest voltage level and largest transmission capacity in the world.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A New Five-Level T-Type Nested Neutral Point Clamped (T-NNPC) Converter
    • Authors: Ahoora Bahrami;Mehdi Narimani;
      Pages: 10534 - 10545
      Abstract: This paper presents a new five-level T-type nested neutral point clamped (T-NNPC) converter. The proposed five-level T-NNPC topology is very attractive for medium-voltage applications as it can work in a wide range of voltages without the need of devices in series, and fewer components compared to the other five-level topologies. A model predictive control (MPC) strategy is also developed for the proposed converter to control the output currents at different output frequencies, and control flying capacitor voltages. A discrete-time model of the converter is developed and the control objectives that are the output currents and flying capacitor voltages are defined regarding switching states. A cost function is defined to minimize the deviation of the predicted values of the control objectives from their desired values. During each sampling time, the best switching state is selected and applied to the converter. The performance of the proposed five-level T-NNPC and the developed MPC strategy is studied in the MATLAB/Simulink environment, and the feasibility of the converter is evaluated experimentally.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Fault-Tolerant Control of Primary Permanent-Magnet Linear Motors With
           Single Phase Current Sensor for Subway Applications
    • Authors: Wei Wang;Yanan Feng;Yan Shi;Ming Cheng;Wei Hua;Zheng Wang;
      Pages: 10546 - 10556
      Abstract: Because both magnets and windings can be mounted in the mover, the primary permanent-magnet linear motor (PPMLM) has a low-cost advantage for subway applications. In this paper, a fault-tolerant control (FTC) with single phase current sensor is proposed for PPMLM traction system in subway applications. In the proposed FTC, d- and q-axis currents are estimated from the reference synchronous currents and the surviving measured phase current. The estimation is robust since no machine parameters are required. In steady-state operation, the estimated current errors are half the actual ones. As a result, the current response is slowed but the current command can be achieved. However, the achievement of control target depends on the current tracking accuracy, which is enhanced by the voltage decoupler. Compared with existed FTC schemes, the proposed one is robust and has better transient-state performances. The effectiveness of the proposed FTC is verified by theoretical analysis and experimental results.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A Multi-Domain Co-Simulation Method for Comprehensive Shifted-Frequency
           Phasor DC-Grid Models and EMT AC-Grid Models
    • Authors: Dewu Shu;Xiaorong Xie;Zheng Yan;Venkata Dinavahi;Kai Strunz;
      Pages: 10557 - 10574
      Abstract: To accurately capture the dynamics of a large-scale ac/dc system as a whole and the interactions between its individual components, a simulation method with high precision and efficiency is in great demand. For this purpose, we develop a multi-domain co-simulation method, in which the target system is partitioned into multiple dc and ac subsystems, represented by our proposed shifted-frequency phasor (SFP) models and the traditional EMT models, respectively. SFP models can be simulated with a much larger time step, leading to a significant improvement in simulation efficiency under a given requirement of precision. Further, a new interface model, namely, hybrid multi-domain transmission-line model (HMD-TLM), is developed to reflect the interactions between SFP models and EMT models, with the additional benefit of producing instantaneous and phasor waveforms simultaneously. Thus, the multi-domain co-simulation is implemented based on the efficient SFP models, the HMD-TLM, and a designed time sequences of simulation. The performance (efficiency and accuracy) of the proposed method has been validated on the well-known CIGRE ac/dc system as well as a practical system integrating large ac grids and modular-multilevel-converter-based multi-terminal dc grids.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A Modular Multilevel Voltage-Boosting Marx Pulse-Waveform Generator for
           Electroporation Applications
    • Authors: Mohamed A. Elgenedy;Ahmed M. Massoud;Shehab Ahmed;Barry W. Williams;Jim R. McDonald;
      Pages: 10575 - 10589
      Abstract: In order to overcome the limitations of the existing classical and solid-state Marx pulse generators, this paper proposes a new modular multilevel voltage-boosting Marx pulse generator (BMPG). The proposed BMPG has hardware features that allow modularity, redundancy, and scalability as well as operational features that alleviate the need of series-connected switches and allows generation of a wide range of pulse waveforms. In the BMPG, a controllable, low-voltage input boost converter supplies, via directing/blocking (D/B) diodes, two arms of a series modular multilevel converter half-bridge sub-modules (HB-SMs). At start up, all the arm's SM capacitors are resonantly charged in parallel from 0 V, simultaneously via directing diodes, to a voltage in excess of the source voltage. After the first pulse delivery, the energy of the SM capacitors decreases due to the generated pulse. Then, for continuous operation without fully discharging the SM capacitors or having a large voltage droop as in the available Marx generators, the SM capacitors are continuously recharged in parallel, to the desired boosted voltage level. Because all SMs are parallelly connected, the boost converter duty ratio is controlled by a single voltage measurement at the output terminals of the boost converter. Due to the proposed SMs structure and the utilization of D/B diodes, each SM capacitor is effectively controlled individually without requiring a voltage sensor across each SM capacitor. Generation of the commonly used pulse waveforms in electroporation applications is possible, while assuring balanced capacitors, hence SM voltages. The proposed BMPG has several topological variations such as utilizing a buck–boost converter at the input stage and replacing the HB-SM with full-bridge SMs. The proposed BMPG topology is assessed by simulation and scaled-down proof-of-concept experimentation to explore its viability for electroporation applications.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Phase-Disposition PWM Based 2DoF-Interleaving Scheme for Minimizing High
           Frequency ZSCC in Modular Parallel Three-Level Converters
    • Authors: Zhongyi Quan;Yun Wei Li;
      Pages: 10590 - 10599
      Abstract: This paper proposes a two-degree-of-freedom (2DoF) interleaving scheme based on phase-disposition (PD) PWM for minimizing the high-frequency zero-sequence circulating current (ZSCC) in modular interleaved three-level converters. The method incorporates an internal interleaving by phase-shifting the carriers in each individual converter, and an external interleaving by phase-shifting the carriers of the different converters. A general harmonic distribution analysis which is valid for all types of voltage source converters is carried out to simplify the evaluation of the proposed method. A comprehensive evaluation of the proposed method shows that the PD-2DoF interleaving scheme produces the lowest ZSCC maximum value as compared to existing approaches. Moreover, it can achieve comparable performances as existing methods do in terms of output quality and common mode voltage magnitude, showing a great potential for practical implementation. Simulation and experimental results are obtained to demonstrate the performance of the proposed method. Generalization of the 2DoF interleaving scheme to high-level converter is also discussed in this paper.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A DC–DC Transformerless High Voltage Gain Converter With Low Voltage
           Stresses on Switches and Diodes
    • Authors: Zahra Saadatizadeh;Pedram Chavoshipour Heris;Mehran Sabahi;Ebrahim Babaei;
      Pages: 10600 - 10609
      Abstract: In this paper, a new dc–dc high voltage gain converter with low-voltage stresses on switches and diodes is proposed. Even though, in the topology of the proposed converter there are not any coupled inductors and transformer utilized, the voltage conversion ratio of the proposed converter is considerable in comparison to its conventional types. Also, two switches of the proposed converter provide longer charge time for two inductors which make the proposed converter capable of providing high voltage gain without preselecting extremely large duty cycles. In addition, the number of power circuit components of the proposed structure are few and the voltage stresses on semiconductor elements are low. In this paper, theoretical analysis of the proposed converter for each operating mode is presented and the voltage gain, voltage and average current stresses of elements, maximum input current ripple, efficiency and equations of critical inductances are calculated. Moreover, to verify the capability of the proposed converter, it is comprehensively compared with other similar recently presented high voltage gain boost converters. Finally, an approximately 12 V/380 V and 520-W prototype of the proposed converter is implemented in laboratory to demonstrate its practical performance, then, the experimental results reconfirm each other and theoretical analysis.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • An Interleaved Totem-Pole Bridgeless Boost PFC Converter with
           Soft-Switching Capability Adopting Phase-Shifting Control
    • Authors: Moo-Hyun Park;Jaeil Baek;Yeonho Jeong;Gun-Woo Moon;
      Pages: 10610 - 10618
      Abstract: This paper proposes an interleaved totem-pole bridgeless boost power factor correction (PFC) converter with soft-switching capability. In the proposed converter, an inductor is added compared with the conventional interleaved totem-pole bridgeless boost PFC converter. The added inductor is located between two PFC converter units, and by utilizing the energy of the added inductor, all switches can achieve the zero voltage switching (ZVS). In addition, by applying the phase-shifting control between two PFC converter units, the proposed converter can control the magnitude of the current flowing on the added inductor as an optimal value. Therefore, the proposed converter can achieve the ZVS operation, while minimizing the additional conduction loss and core loss of the added inductor. As a result, the proposed converter can achieve the high efficiency. The feasibility of the proposed converter is confirmed with 180–264 Vrms input and 1.6 kW (400 V/4 A) output prototype.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • H5+ Converter: A Bidirectional AC–DC Converter With DC-Fault-Blocking
           and Self-Pre-Charge Capabilities
    • Authors: Ye Wang;Yitong Li;Adrià Junyent-Ferré;Minsung Kim;
      Pages: 10619 - 10634
      Abstract: A pulsewidth-modulation bidirectional ac–dc converter (i.e., active rectifier) with dc-fault-blocking and self-pre-charge capabilities is proposed in this paper for low voltage dc (LVdc) applications. The proposed converter, which is named as “H5 + converter,” consists of an H4 bridge, a bidirectional switch, and a transient-voltage-surge (TVS) diode. The bidirectional switch and the TVS diode enable the dc fault blocking and dc bus self-pre-charge, while preserving the low common-mode voltage noise and low leakage current of the converter. Additionally, the proposed H5+ converter has advanced features under a dc-side short-circuit fault, such as fault diagnosis and fault recovery. Operation principles of the proposed converter are presented and analyzed. A down-scaled prototype is built. Experiment results are shown and analyzed, including steady-state waveforms, common-mode performance, start-up dynamics, as well as dc fault blocking, fault diagnosis, and fault recovery. Moreover, the proposed converter is compared with other two dc-fault-blocking converters for LVdc applications, in terms of converter capabilities, required devices, and power switch losses.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A Novel NPC Dual-Active-Bridge Converter With Blocking Capacitor for
           Energy Storage System
    • Authors: Yang Xuan;Xu Yang;Wenjie Chen;Tao Liu;Xiang Hao;
      Pages: 10635 - 10649
      Abstract: In recent years, dc microgrids have been widely concerned for natural interface with renewable energy sources, dc loads, and energy storage systems (ESS). A novel neutral point clamped (NPC) dual-active-bridge (DAB) converter with a blocking capacitor is proposed for ESS in dc microgrids. By inserting a blocking capacitor in primary loop of the traditional NPC DAB converter, the voltage amplitudes across the primary and the secondary windings of the transformer can be matched when the voltage ratio is equal to 0.25, 0.5, 0.75, and 1. Therefore, the proposed topology can adapt to a wide range of energy storage battery voltage variations. Asymmetric pulsewidth modulation plus phase shift modulation are applied to improve the dynamic performance of the proposed converter. The phase-shift ratio between the two bridges and the asymmetric duty ratio are regulated to control the power flow of the proposed NPC DAB converter. Compared with the traditional NPC DAB converter, the proposed topology has lower transformer rms current and wider soft-switching region. Finally, experimental results from a 500-W hardware prototype are presented to verify the feasibility and the advantage of the proposed converter. Compared with the traditional NPC DAB converter, the maximum promotion of efficiency is up to 3.8%.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A Fast and Precise Method for Modeling EMI Source in Two-Level Three-Phase
    • Authors: Yangxiao Xiang;Xuejun Pei;Wu Zhou;Yong Kang;Hanyu Wang;
      Pages: 10650 - 10664
      Abstract: Currently, frequency-domain electromagnetic interference (EMI) modeling has become the most commonly used method for EMI prediction and filter design. However, because of the unpredictability of the ringing effect in the present frequency-domain EMI modeling methods, the precision of the predicted EMI interference source is notably limited, which results in the inaccuracy of the system level EMI prediction. In order to achieve an accurate EMI prediction, this study presents a systematical study on the interference source of a 10 kVA three-phase bridge converter. The precise mathematical models of the common-mode and differential-mode interference source are constructed. Then, the characteristics of the multiple ringing effect, which is an important part of the interference source, are intensively analyzed. Based on the investigation of interference source, an improved interference source synthesis method is proposed. It can quickly and precisely predict the CM and DM interference source with multiple ringing effect, which can be used to achieve accurate frequency domain EMI prediction. Moreover, the multiple ringing effect is extended for IGBT parasitic parameter measuring. Instead of complicated device-level measurement, the grounding capacitance and junction capacitance can be effectively extracted through the ringing frequency measurement.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Broadband Noise Suppression of Stationary Clocked DC/DC Converters by
           Injecting Synthesized and Synchronized Cancellation Signals
    • Authors: Andreas Bendicks;Stephan Frei;
      Pages: 10665 - 10674
      Abstract: Active cancellation of disturbing signals is a common method in electromagnetic compatibility (EMC) of power electronic systems. In this paper, a new method of suppressing periodic disturbances is extended and applied. In this method, the disturbing harmonics are suppressed by a synthesized cancellation signal that is synchronized with the converter's operation. Here, the cancellation signal is synthesized from a number of destructive sine waves. The appropriate amplitudes and phases are found via a convenient and robust adaptive approach. As a special feature of this method, many troublesome effects, like delays or complex frequency characteristics, can be compensated easily. Therefore, this method does not suffer from the same limitations as previous active techniques. Until now, the method has only been proven for a small number of harmonics. In this study, it is applied to a wide frequency range of 150 kHz to 30 MHz of a 48-/12-V dc/dc converter, e.g., for automotive applications. An optimization strategy is developed from a causal model of the system. A test setup is realized, and the sensor's and injector's performances are discussed regarding the automotive EMC standard CISPR 25. Measurement results for the artificial network and the antenna are presented. The additional power losses are estimated.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • PWM Switched Capacitor-Based Cell-Level Power Balancing Converter
           Utilizing Diffusion Capacitance of Photovoltaic Cells
    • Authors: Masatoshi Uno;Yota Saito;Shinichi Urabe;Masaya Yamamoto;
      Pages: 10675 - 10687
      Abstract: This paper proposes a novel pulsewidth modulation cell-level diffusion charge redistribution (DCR) converter based on a switched capacitor converter (SCC) utilizing diffusion capacitance of photovoltaic (PV) cells for PV modules under partial shading. Although a discrete inductor and capacitor are additionally necessary, Joule losses associated with switching operations can be reduced compared to the conventional capacitorless DCR converter. First, ac impedance measurement for a PV cell with 125 × 125 mm was performed, and the diffusion capacitance values were measured to be approximately 6.0 mF at its maximum power point voltage of 0.574 V. Second, the theoretical loss model was derived based on the detailed analysis, and it revealed that an optimal duty cycle achieving the lowest Joule loss was dependent on shading conditions. Third, a dual maximum power point tracking (MPPT) algorithm that controls duty cycles of not only the DCR converter, but a front-end boost converter is also proposed. With the dual MPPT control, the DPP converter operates at its optimal duty cycle to minimize the Joule loss while the boost converter seeks the MPP. The experimental results demonstrated that the maximum power significantly increased, thanks to the DCR converter, and that both the DCR and boost converters operated with respective optimal duty cycles.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A ZVS Three-Port DC/DC Converter for High-Voltage Bus-Based Photovoltaic
    • Authors: Junyun Deng;Haoyu Wang;Ming Shang;
      Pages: 10688 - 10699
      Abstract: In high-voltage bus-based photovoltaic systems, a power electronic interface is required to manage the power flow in between the photovoltaic (PV) panel, battery, and the high-voltage dc bus. In this paper, a novel three-port dc/dc topology is proposed for this application. Pulsewidth and phase-shift offer two degrees of freedom to effectively regulate the power flows. On the primary side, the input current ripple is reduced due to the interleaved structure. This avoids the usage of the bulky electrolytic capacitors on the PV terminal. On the secondary side, a voltage sixfolder rectifier is employed to boost the step-up ratio. This reduces the transformer's secondary-side turns number. Moreover, the voltage stresses of secondary-side mosfets and diodes are reduced to one-third of the output voltage. Zero-voltage switching and zero-current switching are realized among all power mosfets and diodes, respectively, and in an extended range. A 500-W converter prototype, linking a battery pack, a PV panel, and a 760 V dc bus, is designed and tested to verify the proof-of-concept. Both the circuit functionality and theoretical analysis are validated by the experimental results.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Highly Efficient Bridgeless Dual-Mode Resonant Single Power-Conversion
           AC–DC Converter
    • Authors: Sooa Kim;Bong-Hwan Kwon;Minsung Kim;
      Pages: 10700 - 10709
      Abstract: This paper presents a bridgeless dual-mode single power-conversion ac–dc converter that can achieve a high conversion efficiency. By adopting a bidirectional switch, we remove a full-bridge diode rectifier from the grid side of the proposed converter, and thereby, reduce the number of components and the primary-side conduction loss. To adapt the converter to 1-kW power applications with a bidirectional switch, we used a series-resonant circuit in the output voltage doubler on the secondary side. The series-resonant circuit also provides zero-current switching turn-off at the output diode, and thereby, reduces the reverse-recovery loss. To attain medium–high power capability with an appropriate transformer, the proposed converter operates in both discontinuous conduction mode and continuous conduction mode. The operation principle of the converter is presented and analyzed. By using the dual-mode control algorithm, the proposed converter achieves a high power factor of 0.994 and maximum efficiency of 97.3$%$. Experimental results for a prototype 1-kW ac–dc converter verify these characteristics.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Single Phase Bidirectional H6 Rectifier/Inverter
    • Authors: Jianhua Wang;Shang Gao;Yichao Sun;Zhendong Ji;Lexiang Cheng;Lingyu Li;Wei Gu;Jianfeng Zhao;
      Pages: 10710 - 10719
      Abstract: Transformerless photovoltaic (PV) inverters are more widely adopted due to high efficiency, low cost, light weight, etc. However, H5, HERIC, etc., transformerless PV inverters do not have the bidirectional capability for a solar energy storage system in the future. With topology derivation history reviewed from rectifier to inverter, the essence of bidirectional rectifier/inverter is revealed to find a reverse power flow approach. Therefore, this paper proposes an advanced bidirectional technique for a selected H6 inverter topology with only a modulation strategy modified, while the others remain the same. For the H6 circuitry in both rectifier and inverter modes, an excellent three level DM voltage feature is achieved, while leakage current issue is eliminated at the same time with improved modulation method. Simulations and experimental results verify the proposed single phase bidirectional H6 rectifier/inverter technique.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A Carrier Synchronization Method for Global Synchronous Pulsewidth
           Modulation Application Using Phase-Locked Loop
    • Authors: Tao Xu;Feng Gao;Xiongfei Wang;Frede Blaabjerg;
      Pages: 10720 - 10732
      Abstract: When many distributed parallel inverters are integrated into grid without switching sequence coordinated control capability, the high-frequency harmonics will accumulate randomly at the point of common coupling. Global synchronous pulsewidth modulation (GSPWM) method can significantly attenuate the accumulated switching ripples by intentionally assuming an intelligent optimization algorithm and a communication system. To avoid the dependence on low-latency communication system, this paper proposes a novel phase-locked loop based PWM carrier synchronization (PLL-CS) method for GSPWM system, where the switching sequences can be effectively synchronized as expected without using low-latency synchronization signals. By doing so, the operational reliability of the whole GSPWM system can be significantly improved, while the additional hardware cost of GSPWM can be dramatically reduced, which can enhance the implementation adaptability of GSPWM method. Experimental results have verified the performance of the proposed PLL-CS GSPWM method.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Research on Topology of the High Step-Up Boost Converter With Coupled
    • Authors: Si Chen;Luowei Zhou;Quanming Luo;Wei Gao;Yuqi Wei;Pengju Sun;Xiong Du;
      Pages: 10733 - 10745
      Abstract: High step-up boost converters with coupled inductor have attracted much attention in the fuel cell or photovoltaic grid-connected generation system, however, there are few literatures elaborated on the construction ideas and derivation methods of them. Accordingly, in order to obtain a clear roadmap on the derivation and inner connection of these converters, a comprehensive review and analysis are presented in this paper. First, the basic boost converter with coupled inductor is regarded as the basic topology, and its merits and demerits are analyzed in detail. Then, in order to address these demerits, various step-up techniques are introduced, such as the rectifier circuit, the active-clamped circuit, the multi-winding coupled inductor, and the voltage doubler rectifier; and numerous new topologies are continuously proposed by combinations and equivalent simplifications. In addition to a detailed synthesis of each topology, a comparative and quantitative analysis among some important converters is presented, and the optimal one is chosen to build a 250 W prototype. Finally, based on comparisons and analysis, the main characteristics and inner connections of these high step-up boost converters with coupled inductor are identified and clarified.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Integration of Solar PV With Low-Voltage Weak Grid System: Using
           Normalized Laplacian Kernel Adaptive Kalman Filter and Learning Based InC
    • Authors: Nishant Kumar;Bhim Singh;Bijaya Ketan Panigrahi;Chandan Chakraborty;Hiralal Murlidhar Suryawanshi;Vishal Verma;
      Pages: 10746 - 10758
      Abstract: This paper proposes a novel normalized Laplacian kernel adaptive Kalman filter (NLKAKF) based control technique and learning based incremental conductance (LIC) maximum power point tracking (MPPT) algorithm, for low-voltage weak grid-integrated solar photovoltaic (PV) system. Here, a two-stage topology of three-phase grid integrated solar PV system is implemented, where the loads are connected at the point of common coupling. Proposed LIC is the improved form of incremental conductance (InC) algorithm, where inherent problems of traditional InC technique, such as steady-state oscillation, slow dynamic responses, and fixed step size issues, are successfully mitigated. The prime objective of proposed NLKAKF control is to meet the active power requirement of the loads from generated solar PV power, and after feeding load, excess power is fed to the grid. However, when generated PV power is less than the required load power, then NLKAKF control meets the load by taking extra required power from the grid. During this process, power quality is improved at the grid. The controller action provides reactive power compensation, power factor correction, and harmonics filtering and mitigation of other power quality issues. Moreover, when the solar irradiation is zero than voltage source converter acts as a distribution static compensator (DSTATCOM), which enhances the utilization factor of the system. The proposed techniques are modeled and their performances are verified experimentally on a developed prototype, in solar insolation variation conditions, unbalanced loading, as well as in different grid disturbances such as overvoltage, undervoltage, phase imbalance, harmonics distortion in the grid voltage, etc.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • $LC$ +Resonant+Boost+Topology:+Analysis+and+Design&rft.title=IEEE+Transactions+on+Power+Electronics&rft.issn=0885-8993&;&rft.aufirst=Hamed&;Martin+Ordonez;Mohammad+Mahdavi;">High-Efficiency Interleaved $LC$ Resonant Boost Topology: Analysis and
    • Authors: Hamed Valipour;Martin Ordonez;Mohammad Mahdavi;
      Pages: 10759 - 10775
      Abstract: Due to its simplicity, the hard-switching boost converter is widely used in many applications, such as renewable energy and power factor correction. The power density of the converter can be increased with smaller magnetics; however, this requires an increase in the switching frequency. Therefore, it is necessary to provide soft-switching conditions to minimize the switching losses. In this paper, a new resonant step-up converter and the associated analysis are presented. The proposed interleaved LC resonant boost converter provides soft switching for all of the semiconductor elements even under light loading conditions. Small inductors with discontinuous conduction mode (DCM) currents can be used because the interleaving behavior ensures a continuous input current with low ripples. The interleaving also reduces the output capacitor ripple current. Burst mode operation has been applied to improve the efficiency of the converter during light loading conditions. Detailed design methodology and the control strategies are provided. To show the validity of the theoretical analysis, experimental results are provided for a 400-W prototype, and are compared to a benchmark conventional interleaved boost converter with the same components. Substantial efficiency improvements are achieved for different loads and voltage gains, particularly under light loading conditions.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Instantaneous Pulse Power Compensator for High-Density Single-Phase
    • Authors: Xiaofeng Lyu;Na Ren;Dong Cao;
      Pages: 10776 - 10785
      Abstract: In this paper, instantaneous pulse power compensator (IPPC) method is proposed to achieve power pulsation decoupling function for single-phase inverter applications. A smaller capacitor is placed in series with the traditional dc-link capacitor, and this smaller capacitor voltage is controlled using pulse currents to cancel out the dc-link voltage ripple. Unlike twice-line-frequency power decoupling method, the proposed IPPC method can compensate the pulsating power with all the orders harmonics on the dc-link line, not only the second-order component. Both modeling and simulation results show that IPPC method can achieve nearly zero voltage ripple for the dc-link capacitor since the pulse current is fully compensated. Whereas twice-line-frequency power decoupling method has limit in voltage ripple reduction, especially in small dc-link capacitance conditions. The experimental results based on a full-bridge topology decoupling circuit and a single-phase inverter application show consistent results with simulation results. A 16% reduction of the prototype size, i.e., 16% higher power density with only ∼1% efficiency penalty can be achieved by the proposed IPPC method when compared to the second-order power decoupling method.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • An Improved Virtual Capacitor Algorithm for Reactive Power Sharing in
           Multi-Paralleled Distributed Generators
    • Authors: Haizhen Xu;Changzhou Yu;Chun Liu;Qinglong Wang;Fang Liu;Fei Li;
      Pages: 10786 - 10795
      Abstract: Distributed power generators in islanded microgrid usually adopt droop control strategy or virtual synchronous generator (VSG) control strategy to simulate Q–U droop characteristic of synchronous generators for voltage support ability enhancement and reliability improvement. However, because the distributed power generators’ capacities and locations are random, they cannot share reactive load proportional to their rated capacity, resulting in overload protection, and even system instability. In order to improve reactive power sharing precision, voltage control precision, and system stability simultaneously, an improved reactive power sharing algorithm combining virtual impedance and virtual capacitor is proposed in this paper. First, the three existing open-loop reactive power sharing strategies are summarized and the effect of their parameters on reactive power sharing error, steady-state voltage deviation, and system stability are analyzed. Afterwards, based on the analysis results, a reasonable configuration of virtual impedance and virtual capacitor values are put forward to realize the control targets of reducing steady-state reactive power sharing error, improving voltage control precision and system stability meanwhile. Finally, simulation and experimental platforms are built to verify the effectiveness of the proposed strategy.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Efficient Improvement of Photovoltaic-Battery Systems in Standalone DC
           Microgrids Using a Local Hierarchical Control for the Battery System
    • Authors: Yun Yang;Yaxiao Qin;Siew-Chong Tan;Shu Yuen Ron Hui;
      Pages: 10796 - 10807
      Abstract: The conventional control methods for the battery systems of photovoltaic (PV) battery systems in standalone dc microgrids are designed to stringently regulate the bus voltages at the maximum power points (MPP) of PV modules while the state of charge (SOC) of the battery packs is regulated within the tolerances. In this paper, a local hierarchical control (LHC) is proposed for the battery system to improve the energy efficiency of the entire PV-battery system at the MPP of PV modules while the SOC of the battery pack is still regulated within the tolerance. Specifically, by allowing the dc bus voltage to deviate within a preset allowable tolerance, the secondary control of the LHC is employed to compute real-time optimal references to its primary control, such that the energy conversion of the entire PV-battery system can be optimized. Simulation studies exhibit significant efficiency improvement of a 12-PV-battery system under both uniform and nonuniform insolation conditions on a cloudy day and a 600-kW PV-battery system on a sunny day using the proposed LHC. Experimental results validate that the energy efficiency of a single-PV-module-battery system controlled by the LHC can be enhanced using shortened sunny-day and cloudy-day irradiance profiles for various PV modules. The proposed control scheme can be easily implemented in digital controllers without additional hardware costs.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Performance Investigation of Multifunctional On-Grid Hybrid Wind–PV
           System With OASC and MAF-Based Control
    • Authors: Subarni Pradhan;Shadab Murshid;Bhim Singh;Bijaya Ketan Panigrahi;
      Pages: 10808 - 10822
      Abstract: An observer-based adaptive speed control (OASC) and a multistage adaptive filter (MAF) based control structure are proposed for an on-grid hybrid wind–photovoltaic (PV) system to deal with the two major issues such as peak wind power extraction and mitigation of power quality problems, respectively. The OASC is an adaptive control alongside exhibiting robustness against uncertainties (structured and unstructured). The objective of peak wind power extraction is met through cascaded control, which includes an inner hysteresis current control and an outer speed control based on OASC. The proposed OASC includes a disturbance observer loop with backstepping control. Moreover, it incorporates a discontinuous projection law-based adaptive parameter estimation, thereby resulting in a sense of hybrid control implementation. The outer speed control loop provides the reference stator current to the inner loop retaining maximum power point tracking. For enhancement of system reliability, another renewable source (solar PV array) is integrated at the dc link. The connection between the hybrid system and the grid is established through an inverter incorporating the proposed MAF-based control. Herein, the effects of nonlinear balanced and unbalanced loads are addressed through the incorporation of vectorial approach for extracting fundamental positive sequence components from nonlinear load currents to realize harmonic-free fundamental reference currents for the grid. The proposed controls are simulated and compared with the conventional techniques. The control implementation and performance testing are carried out on the hybrid system built in the laboratory.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Optimal Dead-Time Control Scheme for Extended ZVS Range and Burst-Mode
           Operation of Phase-Shift Full-Bridge (PSFB) Converter at Very Light Load
    • Authors: Chong-Eun Kim;
      Pages: 10823 - 10832
      Abstract: Phase-shift full-bridge (PSFB) converter is a widely used topology for high-efficiency and high-power applications, thanks to low voltage/current stress of all components and zero-voltage-switching operation of primary mosfets. The critical drawback of the PSFB converter is hard-switching characteristics of primary mosfets at a very light load, which causes severe thermal explosion and extremely high input power consumption, especially with the latest super-junction mosfet. To minimize the switching loss of the PSFB converter at a very light load, a new optimal dead-time control scheme with burst-mode operation is proposed in this paper and its validity is verified experimentally with the implemented 2.2-kW server power supply unit.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • High-Power-Density Single-Phase Three-Level Flying-Capacitor Buck PFC
    • Authors: Wenlong Qi;Sinan Li;Huawei Yuan;Siew-Chong Tan;Shu-Yuen Hui;
      Pages: 10833 - 10844
      Abstract: Active pulsating power buffering (PPB) is an effective technique to reduce the energy storage requirement of a single-phase power-factor-correction (PFC) rectifier. Existing single-phase solutions with active PPB, however, generally suffer from high voltage stresses, leading to increased power losses as well as the need for high-voltage-rating semiconductor switches. Previous works have been focusing on two-level switching converter configurations, and thus have failed to address the high-voltage-stress problem. In this paper, a single-phase three-level flying-capacitor PFC rectifier with PPB-embedded switching is proposed. The flying capacitor not only clamps the voltage stresses of all power devices but also functions as a PPB capacitor. The operating principles, control methods, and design guidelines are detailed and the feasibility of the proposed converter is verified through a 48-W (48-V/1-A) hardware prototype. The proposed rectifier is shown to achieve nearly 50% reduction of the voltage stresses, 72% reduction of the buffering capacitor's volume, and 23.8% reduction of the magnetic core size, as compared to a state-of-the-art two-level solution recently proposed. This new approach of formulating single-phase PFC rectifiers with active PPB could dramatically boost the system's efficiency and power density whilst reducing cost.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Spread Spectrum Technique for Decreasing EM Noise in High-Frequency APWM
           HB Resonant Converter With Reduced EMI Filter Size
    • Authors: Hwa-Pyeong Park;Sangyeong Jeong;Mina Kim;Jingook Kim;Jee-Hoon Jung;
      Pages: 10845 - 10855
      Abstract: A spread spectrum technique (SST) has been proposed as a solution to mitigate electromagnetic (EM) interference in power converters. In the previous research, the SST has been widely applied to the power converters that have insensitive voltage gain according to switching frequency variation, such as buck, boost and flyback topologies. However, resonant converters have sensitive voltage gain according to the switching frequency variation, which cannot regulate the output voltage with the SST. In this paper, a high-frequency (HF) half-bridge (HB) resonant converter employing the SST is developed for power supply applications with 100-W power capability. The design methodology of its resonant tank and the SST is proposed to obtain the tight output voltage regulation performance and the EM noise reduction. In addition, the size reduction of EM noise filters is analyzed by employing the SST. The output voltage regulation performance and the filter size reduction will be experimentally verified using a 100-W prototype HF HB resonant converter.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A Gallium Nitride (GaN)-Based Single-Inductor Multiple-Output (SIMO)
           Inverter With Multi-Frequency AC Outputs
    • Authors: Weijian Jin;Albert Ting Leung Lee;Siew-Chong Tan;Shu Yuen Hui;
      Pages: 10856 - 10873
      Abstract: In this paper, a gallium nitride (GaN)-based single-inductor multiple-output (SIMO) dc–ac inverter, which generates multiple frequencies at the ac outputs, is introduced. The proposed time-multiplexed switching sequences enable the SIMO inverter to simultaneously generate sinusoidal-like outputs with different frequencies. In the absence of a parasitic body diode in the GaN transistor and with correct bias voltage, the proposed inverter requires no additional blocking diodes and/or cascaded power switches while still ensuring unidirectional flow of the inductor current for proper circuit operation. Compared with its silicon counterpart, this GaN-based inverter achieves a simplified circuit structure, reduced component count, small form factor, increased power density, and high efficiency. A practical application of this inverter is to act as a single wireless power transmitter which concurrently drives multiple transmitter coils at different frequencies for multi-standard wireless power transfer. A hardware prototype of a single-inductor three-output inverter producing three distinct resonant frequencies, namely, 100, 200, and 300 kHz, is constructed. The effectiveness of the proposed switching sequences and control method for this inverter is experimentally verified. No cross regulation is observed across the three individual ac outputs.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A Two-Switch, Isolated, Three-Phase AC–DC Converter
    • Authors: Yungtaek Jang;Milan M. Jovanović;Misha Kumar;Yihua Chang;Yi-Wei Lin;Chun-Liang Liu;
      Pages: 10874 - 10886
      Abstract: A new, three-phase, single-stage, isolated ac–dc converter (rectifier) that employs only two switches and achieves less than 5% total harmonic distortion of the three-phase input currents and provides a tightly regulated, isolated, output voltage is introduced. The rectifier features zero-voltage-switching of both switches over the entire input and load range without any additional soft-switching circuitry. The rectifier is derived by combining the three-phase, power-factor-correction, discontinuous-current-mode boost rectifier that is also known as Taipei rectifier with the conventional LLC resonant half-bridge converter. The introduced rectifier requires single feedback loop with frequency control to regulate the output voltage. The evaluation was performed on a 1-kW prototype operating with a three-phase line-voltage range from 180 to 264 $V_{text{L}-text{L}}$ and delivering a tightly-regulated, isolated, output voltage of 54 V. The measured efficiency of the prototype at nominal line voltage VIN = 208 VL-L is above 95% from 90% of full load down to 50% of full load. The maximum voltage stress is approximately 430 V.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Characteristics of Isolated DC–DC Converter With Class Phi-2 Inverter
           Under Various Load Conditions
    • Authors: Yuta Yanagisawa;Yushi Miura;Hiroyuki Handa;Tetsuzo Ueda;Toshifumi Ise;
      Pages: 10887 - 10897
      Abstract: The development and application of gallium nitride–heterojunction field-effect transistor (GaN–HFET) has been actively researched. Because GaN–HFETs have advantages in high-frequency operation, it is possible to downsize power converters by increasing the switching frequency. As the switching frequency rises, the switching loss increases in proportion to the frequency; therefore, application of a soft-switching method is needed to decrease the losses and heat generation. The resonant power conversion circuits represented by the class Phi-2 inverter have soft-switching feature; therefore, these circuits realize low-switching-loss operation even in high-frequency regions. However, the operation of these resonant circuits depends on the load conditions, generally. Thus, it is important to investigate the characteristics of the inverter for various load conditions. In this paper, we investigate the characteristics of the non-isolated and isolated class Phi-2 inverters by changing the load resistance and the duty ratio of the boost circuit connecting after the class Phi-2 circuit, which is operated at 13.56 MHz. We also developed a protection system during abnormal operations such as an open circuit. From experimental results, the class Phi-2 inverter has superior characteristics under various load conditions and changes. Moreover, we confirmed the effectiveness of the abnormal operation stop system.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Cross Interference Minimization and Simultaneous Wireless Power Transfer
           to Multiple Frequency Loads Using Frequency Bifurcation Approach
    • Authors: R. Narayanamoorthi;A. Vimala Juliet;Bharatiraja Chokkalingam;
      Pages: 10898 - 10909
      Abstract: Simultaneous power distribution to multiple loads using a single source in the wireless power transfer (WPT) system is a challenging issue due to cross-coupling between the load coils, which reduces the power transfer efficiency. In a resonant WPT system, when two or more coils operated under over coupled condition, the original operating resonant frequency gets bifurcated, and thereby reduction in the power transfer efficiency. Different techniques are investigated in the literature to mitigate the frequency bifurcation phenomena in the resonant WPT system. However, the utilization of frequency bifurcation approach for the simultaneous power transfer to multiple loads is not addressed. This paper proposes a simultaneous power transfer approach using frequency bifurcation for the multiple load system designed with different operating frequency. Mathematical, simulation, and experimental studies performed for dual, triple, and four coil WPT systems with multiple loads. In addition, an automatic power flow control method is implemented to estimate the load current from the source, which helps to select a new set of load coils to be charged. The experimental results confirm the proposed power transfer, helps to attain higher power transfer efficiency of 39.34%, 49.31%, 68.22% and cross interference of −31.2 dBV, −36.2 dBV, −41.2 dBV for dual, triple, and four coil WPT system, respectively.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A Theory to Synthesize Nonisolated DC–DC Converters Using Flux
           Balance Principle
    • Authors: Soumya Shubhra Nag;Ramanuja Panigrahi;Santanu K. Mishra;Avinash Joshi;Khai D. T. Ngo;Suman Mandal;
      Pages: 10910 - 10924
      Abstract: This paper describes a theory to synthesize nonisolated dc–dc converters. It uses the fundamental flux balance equation across the inductors of a converter as a starting point in this synthesis process. The flux balance equations are the linear equations of the input voltage, capacitor voltages, and duty cycle (D). The coefficients of these linear equations can be selected from a finite set of choices. These choices define the converter topologies that are subsequently used to synthesize a converter. The synthesis procedure applies to a converter of multiple order. All the possible converters are identified for a first-order topology. In the case of second-order converters, all the choices of the flux balance equation are defined. Based on these choices, three new quadratic topologies are derived and verified to demonstrate the effectiveness of the theory. The procedure to synthesize a converter from a given voltage conversion ratio is also outlined.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Design and Modeling of an Equalizer for Fuel Cell Energy Management
    • Authors: Milad Bahrami;Jean-Philippe Martin;Gaël Maranzana;Serge Pierfederici;Mathieu Weber;Farid Meibody-Tabar;Majid Zandi;
      Pages: 10925 - 10935
      Abstract: During the lifespan of a polymer electrolyte membrane fuel cell (PEMFC) system, some heterogeneities between the cells constituting the stack can appear. The voltage of one particular cell in a stack may decrease because of specific aging or local malfunctioning such as drying. As a result, more heat is generated in this cell leading to an increase in its temperature and, thus, an additional voltage loss. This snowball effect can result in the failure of the cell. Therefore, the lifetime of a PEMFC stack can be increased by applying energy management to its cells. Note that the output voltage of a cell is lower than a stack. Hence, a high conversion ratio converter is necessary to implement such energy management. An efficient way to increase the output voltage is to connect the output capacitors of the converters such as the boosts in series. Ensuring the converters’ controllability is a key point to implement energy management. In this paper, an equalizer system is proposed to ensure the controllability of the boost converters. The balancing speed and the low number of switches are the main advantages of this system. The validity of the proposed system is verified through simulation and experiments.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • High-Step-Down DC–DC Converter With Continuous Output Current Using
    • Authors: Marziyeh Hajiheidari;Hosein Farzanehfard;Ehsan Adib;
      Pages: 10936 - 10944
      Abstract: This paper proposes a high-step-down dc–dc converter with continuous output current which utilizes coupled-inductors. Another main feature of this converter is applying the same number of switches as the synchronous buck converter. The introduced converter is suitable for non-isolated low-voltage high-current applications, especially voltage regulator modules (VRMs) with 12-V-input. Owing to extension of the duty cycle, the main mosfet current stress and the synchronous rectifier switch voltage stress are significantly reduced. However, the discharge of the leakage inductance energy increases the main mosfet voltage stress. By employing a simple lossless clamp/snubber circuit the leakage inductance energy is recovered, the voltage spike across the main mosfet is clamped, and the turn-off switching losses are reduced. There is at least one inductor in all current paths which creates an intrinsic protection against current shoot-through and provides zero-current-switching (ZCS) turn-on for the main mosfet. High efficiency is attained by the proposed converter due to extended duty cycle, low number of switches, and soft switching operation while the converter driver is just like the conventional buck converter. Due to the single-phase structure of the proposed converter, this converter is a viable alternative to the buck VRM. Similar to the other converters using coupled-inductors, the complexity of coupled-inductors design and the space occupied by coupled-inductors can be considered as drawbacks. A prototype of the proposed converter is implemented to verify the converter operation and the theoretical analysis.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Phase-Shifted Full-Bridge DC–DC Converter With High Efficiency and High
           Power Density Using Center-Tapped Clamp Circuit for Battery Charging in
           Electric Vehicles
    • Authors: Cheon-Yong Lim;Yeonho Jeong;Gun-Woo Moon;
      Pages: 10945 - 10959
      Abstract: In this paper, a phase-shifted full-bridge (PSFB) converter employing a new center-tapped clamp circuit is proposed to achieve high efficiency and high power density in electric-vehicle battery charger applications. By using a simple center-tapped clamp circuit, which consists of two diodes and one capacitor, many limitations in conventional PSFB converters are solved. The proposed center-tapped clamp circuit provides the clamping path and allows the secondary voltage stress to be clamped to the secondary-reflected input voltage. This results in a greatly reduced conduction loss in the secondary full-bridge rectifier (FBR) due to the low-forward-voltage drop of low-voltage-rated diodes, and the resistor–capacitor–diode snubber loss is eliminated. In addition, the circulating current in the primary side is removed without any duty-cycle loss. Furthermore, the turn-off switching loss in the FBR is substantially reduced due to the decreased reverse-recovery current and the reduced reverse voltage. With these advantages, high efficiency can be achieved. Besides, the size of the output inductor is considerably reduced with the aid of clamping voltage, resulting in a high power density with saving the cost. In order to confirm the effectiveness of the proposed converter, a 3.3-kW prototype was tested. Experimental results show that the proposed converter achieves high efficiency over the entire conditions with high power density.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Near-Unity Power Factor, Voltage Step-Up/Down Conversion Pulse-Width
           Modulated Switching Rectification for Wireless Power Transfer Receiver
    • Authors: Philex Ming-Yan Fan;Mohamad Hazwan bin Mohd Daut;
      Pages: 10960 - 10969
      Abstract: The pulse-width modulated (PWM) switching rectification that can achieve a high power factor (PF) for increasing the energy transfer efficiency between an LC resonator and a rectifier and voltage step-up and -down conversion is proposed for a wireless power transfer (WPT) receiver. The proposed method can emulate the switching rectifier as a resistive load by using an inductor and integrated phase synchronizers. Additionally, similar to a switched-inductor converter that controls the duty cycle ratio (D), the proposed PWM rectifier can control the output voltage VOUT when the input is a rectified, wirelessly coupled voltage instead of a constant voltage. Thus, unlike a conventional PWM switching rectifier for ac mains, an additional voltage conditioning circuit would not be needed after the proposed rectifier for WPT. The proposed PWM switching rectification is implemented in the AMS 0.18 μm 1.8 V/5 V CMOS process. PF = 1 is measured, indicating the most efficient energy transfer, compared to only 0.55–0.65 in a peak detection rectifier. Additionally, 88.2% of peak power conversion efficiency of the switching rectifier is achieved, and the maximum output power is 80.3 mW at 500 kHz of the WPT frequency. Moreover, the measured voltage conversion ratios ranging between 0.73× and 2× are demonstrated in this paper.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • LLC Synchronous Rectification Using Resonant Capacitor
    • Authors: Jhih-Da Hsu;Martin Ordonez;Wilson Eberle;Marian Craciun;Chris Botting;
      Pages: 10970 - 10987
      Abstract: Synchronous rectification (SR) for LLC resonant converters has been developed to enhance the power conversion efficiency and achieve high-power-density design. Conventional SR driving strategies can be categorized as current-driven methods, $v_{text{DS-ON}}$ sensing methods, and alternative approaches. The current-driven methods widely adopt current transformers (CTs) to sense the rectifier current and generate the SR driving signals. The CTs are lossy and bulky, which is unfavorable to high-power-density design. The $v_{text{DS-ON}}$ sensing methods remove the current sensors by sensing the voltage across the on-state resistor of the SR mosfet, yet the sensed signal is small and prone to be offset by the inductive voltage induced from parasitic components. Most alternative approaches avoid sensing noise-sensitive signals; however, the operating range is narrow due to the limited information from the converter. This paper proposes an SR driving strategy based on the resonant capacitor voltage (RCV) to address those issues. The RCV SR driving strategy does not require current sensors. The sensed RCV is insensitive to the parasitic effects. In addition, the RCV strategy controls the SR on-time effectively over a wide range of operating frequency and loading conditions. Simulation and experimental results of a 650-W/24-V LLC converter are presented to validate the effectiveness of the proposed RCV strategy. Compared with the conventional $v_{text{DS-ON}}$ sensing method, the on-time error caused by the parasitic effect is greatly reduced, which improves the power conversion efficiency and reduces the SR mosfet temperature.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A Carrier-Based Fault-Tolerant Control Strategy for T-Type Rectifier With
           Neutral-Point Voltage Oscillations Suppression
    • Authors: Jie Chen;Chenghui Zhang;Alian Chen;Xiangyang Xing;Feng Gao;
      Pages: 10988 - 11001
      Abstract: This paper proposes a carrier-based fault-tolerant control strategy for T-type three-level rectifier with neutral-point (NP) voltage oscillations suppression when an open-circuit fault occurs. The proposed fault-tolerant control is demonstrated by dividing fault into two conditions: the faulty condition of outer switches and inner switches. In the case of outer switches open-circuit fault, the requirement to maintain the normal operation with sinusoidal currents is demonstrated. Meanwhile, in order to suppress the NP voltage oscillations, a hybrid NP voltage control strategy, which is implemented by adding a compensation value to the reference voltage, and a dc bias are used. In the case of inner switches open-circuit fault, the fundamental period of the input current is divided into two areas: normal half-cycle and abnormal half-cycle. In the abnormal half-cycle, the reference voltage of the faulty leg is compared with a single carrier. In addition, a compensation value is added to the reference voltage to suppress the NP voltage oscillations. While in the normal half-cycle, the hybrid NP voltage control strategy and the dc bias are applied. The feasibility and performance of the proposed tolerant control are illustrated and verified through the simulation and experimental results.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A New Non-Isolated Low-Power Inductorless Piezoelectric DC–DC
    • Authors: Benjamin Pollet;Ghislain Despesse;François Costa;
      Pages: 11002 - 11013
      Abstract: We present a new non-isolated low-power inductorless piezoelectric resonant converter. The piezoelectric material is used as an energy storage element like an inductance in a classical buck–boost power electronic converter. As opposed to most existing piezoelectric converters, the proposed topology enables to dynamically adjust the output power and ratio keeping a high efficiency for a large range of output powers and for a large range of conversion ratios taking advantage of piezoelectric high-quality factor and achieving zero-voltage switching. A theoretical analysis of the step-up converter using an energetic approach is introduced and enables a fast and reliable predesign of the piezoelectric component. This analysis is in perfect agreement with the simulation model performed on MATLAB/Simulink. For a given piezoelectric resonator both analytical and simulation models provide very high efficiencies for different output powers. The converter is tested experimentally with a 10 V input voltage using the piezoelectric radial resonance mode. An efficiency higher than 98% for a 160 mW power conversion is achieved, decreasing slowly to 78% at 1.4 W. For a large range of voltage gains, the efficiency remains higher than 90% up to an output power of 750 mW. The experimental results are in perfect agreement with the theoretical analysis until 500 mW.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Topology and Modulation Scheme for Three-Phase Three-Level Modified
           Z-Source Neutral-Point-Clamped Inverter
    • Authors: Anh-Vu Ho;Tae-Won Chun;
      Pages: 11014 - 11025
      Abstract: This paper presents the topology and modulation technique of a three-phase three-level modified Z-source neutral-point-clamped (MZS-NPC) inverter, which combines a modified Z-source impedance network and a three-phase three-level NPC inverter. The boost factor of the proposed MZS-NPC inverter is twice as high as the three existing representative topologies combing an impedance network with a three-level NPC inverter. A modulation scheme for the proposed topology, based on a maximum boost control method, is designed to achieve the maximum voltage gain with simple implementation and to balance the dc-link neutral-point voltage. A closed-loop control of the ac load voltage in the fuel-cell or photovoltaic applications based on the proposed inverter is realized, in order to supply a desired voltage to the critical load in islanding mode of a microgrid. The boosting ability and operation validity of the proposed topology and modulation technique are demonstrated with simulation and experimental results.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Magnetic Integration Into a Silicon Carbide Power Module for Current
    • Authors: Zichen Miao;Yincan Mao;Guo-Quan Lu;Khai D. T. Ngo;
      Pages: 11026 - 11035
      Abstract: Threshold-voltage mismatch among paralleled dies leads to unbalanced turn-on peak currents and switching energies, thus degrading reliability. A passive method employing inversely coupled inductors of tens of nH and drive-source resistors reduces current unbalance. An integrated design of the coupled inductors is required to facilitate their practical use in a power module. A layout to achieve inverse coupling, high coupling coefficient, and low voltage stress, magnetic materials suitable for operation at tens of MHz, and high current rating of tens of amperes with small magnetic core are challenging for its implementation. A module with integrated coupled inductors that achieve inverse coupling by utilizing the copper trace of the substrate and bond wires, size comparable to the silicon carbide die, coupling coefficient higher than 0.98, tens of nH operating at tens of MHz, and current rating of tens of amperes was designed, fabricated, and validated in this work. The coupled inductors with magnetic material of low-temperature cofired ceramics are compatible with existing packaging technology for module fabrication. Effectiveness on reducing transient-current mismatch at various input voltages, load currents, and gate resistances was verified by experiments. Compared with the baseline module resembling commercial modules, the module with integrated coupled inductors reduces current unbalance from 36% to 6.4% and turn-on energy difference from 28% to 2.6% while maintaining the same total switching energy and negligible change of voltage stress.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A Study on the Effect of Microstructure Evolution of the Aluminum
           Metallization Layer on Its Electrical Performance During Power Cycling
    • Authors: Jingyi Zhao;Tong An;Chao Fang;Xiaorui Bie;Fei Qin;Pei Chen;Yanwei Dai;
      Pages: 11036 - 11045
      Abstract: The study presented in this paper contributes to the quantification of the correlations between resistance degradation and Al metallization layer reconstruction observed in high-power insulated gate bipolar transistor (IGBT) modules during power cycling. The microstructure evolution that occurs in the Al metallization layer during power cycling was investigated via electron and ion microscopy, and the surface roughness was measured and used to characterize Al metallization degradation. An electrical four-point probe method was used to examine the change in the electrical parameter (resistance) of the Al metallization layer in the IGBT modules. The effect of the Al metallization layer reconstruction on its electrical performance was investigated by experimental observation and finite-element analysis (FEA). The results show that both the Al metallization layer surface morphology and cracks propagating across the Al metallization layer thickness significantly affect the metallization resistance. In the initial and mid-point stages of power cycling, the increase in the Al metallization layer resistance is consistent with the surface roughness evolution. Near the ultimate lifetime of the IGBT module, the change in the resistance strongly depends on the crack density.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Predictive Cascaded Speed and Current Control for PMSM Drives With
           Multi-Timescale Optimization
    • Authors: Wencong Tu;Guangzhao Luo;Zhe Chen;Longran Cui;Ralph Kennel;
      Pages: 11046 - 11061
      Abstract: This paper proposes a predictive speed and current control with multi-timescale optimization in a cascade architecture for a permanent-magnet synchronous motor. Considering the difference of timescale characteristics for speed loop and current loop, different sampling times are assigned to the respective subsystem. In the prediction step of the conventional two-timescale system, the coupling between slow and fast sampling models is ignored and the output of the slow-sampling model at asynchronous sampling period is missing, which both weaken the prediction performance of the system. In this paper, the predictions of both slow and fast models for all the prediction instants are analyzed in detail. Besides, a linear estimation method based on virtual instants is proposed to improve the performance of the slow-sampling model for fast prediction instants. The data stream of the proposed method is designed based on the cascaded structure. The strategies are implemented on a field-programmable gate arrays taking advantages of parallel and pipeline processing techniques. Experimental results show that the proposed strategies have a better dynamic performance compared to the conventional method.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Study on a Three-Phase Inductor Based on Equal Magnetic Flux Path
    • Authors: Jianfen Zheng;Chunfang Wang;Dongwei Xia;
      Pages: 11062 - 11070
      Abstract: Owing to a uniform air-gap distribution of the magnetic powder materials, it is found that the conventional structure of a three-phase inductor made of magnetic powder cores will cause the three-phase magnetic flux paths to be unequal, thereby making the three-phase input voltages of a pulsewidth modulation (PWM) rectifier imbalanced. This paper presents a novel magnetic powder core structure applicable to a three-phase inductor for PWM rectifier. An equal magnetic flux path for the inductor core is designed to solve the imbalance problem of three-phase voltages. The proposed design is based on measuring the maximum flux density and the inductance values, modeled with electromagnetic simulation of a three-dimensional finite-element method. Simulation and experimental results of the proposed design show that it reduces the three-phase voltage imbalance to less than 3%. Furthermore, the unit volume of the three-phase inductor is reduced by 34% and 23%, and the efficiency is increased by 1.2% and 0.9%, compared to those of a conventional three-phase silicon-steel core inductor and three single-phase inductors, respectively.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Control of Dual Three-Phase Permanent Magnet Synchronous Machine Based on
           Five-Leg Inverter
    • Authors: Yashan Hu;Shoudao Huang;Xuan Wu;Xuefei Li;
      Pages: 11071 - 11079
      Abstract: This paper proposes a current control of dual three-phase permanent magnet synchronous machine (PMSM) based on five-leg inverter. The five-leg inverter can be utilized to drive dual three-phase PMSM with full torque at slow speed when the conventional dual three-phase voltage source inverter (VSI) has a faulty inverter leg. Usually, the common leg in the five-leg inverter may have severe current stress. By dedicated selection of which two phases as a pair to share the common leg, its current rating is approximately half of current rating of other legs. Meanwhile, the five-leg inverter can fully fulfill the vector space decomposition control for dual three-phase PMSM, which has the same dynamical performance as the conventional dual three-phase VSI. However, due to the asymmetry of five-leg inverter non-linearity, the currents of dual three-phase PMSM are unbalanced. To mitigate this issue, the five-leg inverter non-linearity compensation is also introduced and investigated in this paper, whose effectiveness is verified by comparative experiments on a prototype dual three-phase PMSM.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Effective Turn Fault Mitigation by Creating Zero Sequence Current Path for
           a Triple Redundant 3 × 3-Phase PMA SynRM
    • Authors: Bo Wang;Jiabin Wang;Antonio Griffo;Wei Hua;
      Pages: 11080 - 11089
      Abstract: Effective mitigation of excessive stator turn fault current is crucial for fault tolerant machine drives. In this paper, a simple and effective method is proposed for a triple redundant 3 × 3-phase permanent magnet-assisted synchronous reluctance machine by using three 3-phase 4-leg inverters. The fourth leg creates a zero sequence current path when a terminal short circuit is applied in an event of a turn fault in a 3-phase winding set. Consequently, the zero sequence flux linkages are reduced by the resultant zero sequence current. This leads to lower residual flux linkage and decreased fault current. The machine drive can therefore have larger safety margin or can be designed for improved torque density and efficiency. The proposed approach is verified by both finite element (FE) simulations and experimental tests in a wide operation range. It shows that the fault current is reduced by ∼40% and the output torque is not affected.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Performance Evaluation and Reliability Enhancement of Switched Reluctance
           Drive System by a Novel Integrated Power Converter
    • Authors: Shuai Xu;Hao Chen;Jian Yang;Feng Dong;
      Pages: 11090 - 11102
      Abstract: In this paper, the performance and reliability of a cost-effective novel integrated power converter (NIPC) are investigated in comparison to the asymmetric half-bridge power converter (AHBPC) for switched reluctance drive (SRD) system. First, with the soft chopping manner, the working modes and voltage equations of NIPC are illustrated to develop the conventional control strategies. Second, given that the power switches are the reliability-critical devices of converters, a novel control strategy is put forward to shorten the operation time and lower the electrical stress of power switches. Besides, the SRD system with NIPC can still operate with the faults of power switches, especially the output torque of faulty phase is not zero when the open-circuit fault happens. But in order to further enlarge the output torque of faulty phase and lower the torque ripple, the fault-tolerance strategy is proposed. Next, to effectively evaluate the topologies from the perspective of reliability, a unified Markov model is introduced to conduct the static and dynamic reliability analysis, illustrating that the reliability of NIPC is evidently higher than AHBPC. Finally, the simulation and experiments on a prototype SRD system are developed to verify the effectiveness of proposed NIPC and corresponding control strategies.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Offline Parameter Self-Learning Method for General-Purpose PMSM Drives
           With Estimation Error Compensation
    • Authors: Qiwei Wang;Guoqiang Zhang;Gaolin Wang;Chengrui Li;Dianguo Xu;
      Pages: 11103 - 11115
      Abstract: Offline parameter identification of permanent magnet synchronous machines (PMSMs) is of great importance for general-purpose drives with sensorless control. This paper proposes an amplitude-auto-adjusting signal injection (ASI) method for the parameter self-learning of PMSMs at standstill considering inverter nonlinearities and the digital time-delay effect. The ASI method achieves the inductance identification process under various dq-axis currents and at the same time prevents the unexpected rotor rotation during the self-commissioning process. For the test PMSM, the spatial inductance maps of dq-axes and abc-phases concerning the magnetic saturation and cross-coupling effects are identified along with the stator resistance. To enhance the estimation accuracy, an error model of the inverter nonlinearities in dq-axes is established, and a compensation method independent of inverter parameters is proposed based on the Hermite interpolation. In addition, the influence of the digital time-delay effect is analyzed and compensated based on the transient model of the circuits. The effectiveness of the proposed parameter self-learning scheme is confirmed on a 2.2-kW PMSM drive. The accuracy of the experimental results is validated by finite element analysis on the test machine.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Open-Phase Fault Modeling and Optimized Fault-Tolerant Control of Dual
           Three-Phase Permanent Magnet Synchronous Machines
    • Authors: Guodong Feng;Chunyan Lai;Wenlong Li;Jimi Tjong;Narayan C. Kar;
      Pages: 11116 - 11127
      Abstract: This paper investigates open-phase fault modeling and fault-tolerant control (FTC) of dual three-phase permanent magnet synchronous machines (DT-PMSMs). A comprehensive fault model that considers both the permanent magnet torque and reluctance torque under the open-phase fault is proposed first. This model shows that under open-phase fault the average torque of DT-PMSM will decrease, while torque ripple will increase significantly. Then, a novel optimized FTC approach is developed based on the proposed model, in which genetic algorithm (GA) is applied to optimize the stator currents to maximize the average torque and minimize the torque ripple under open-phase fault. The proposed fault model and GA-based FTC are applicable to both surface-mounted and interior DT-PMSMs. However, existing approaches neglecting the reluctance torque are only applicable to surfaced-mounted DT-PMSMs. Moreover, the proposed approach is simple in implementation as it employs the original control structure and it is capable of smooth switching between the healthy operation and FTC without inducing noticeable torque pulses. The proposed approach is demonstrated with design examples, compared with existing one and validated with experiments on a laboratory interior DT-PMSM.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Motor Overvoltage Mitigation on SiC MOSFET Drives Exploiting an Open-End
           Winding Configuration
    • Authors: Salvatore De Caro;Salvatore Foti;Tommaso Scimone;Antonio Testa;Giacomo Scelba;Mario Pulvirenti;Sebastiano Russo;
      Pages: 11128 - 11138
      Abstract: Voltage wave reflection phenomena along power cables are particularly threatening on ac motor drives equipped with silicon carbide power mosfets due to very short switching times and high switching frequency. Overvoltage suppression resistance inductance capacitance (RLC) networks are usually added but leading to extra cost and a lower efficiency. A completely different overvoltage mitigation approach is presented in this paper exploiting an open-end winding motor configuration. Overvoltage occurring on the terminals of motor phase windings are, in fact, mitigated by simply coordinating the operations of the two inverters; thus, no passive RLC networks are required. The proposed approach is intended as a mean to provide a further valuable feature to open-winding systems at no extra cost, but it can be also valued as an alternative to conventional bridge inverters equipped with overvoltage mitigation devices.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Multilayer Flexible Printed Circuitry Planar Transformer With Integrated
           Series Capacitance for an LLC Converter
    • Authors: Godwin Kwun Yuan Ho;Bryan M. H. Pong;
      Pages: 11139 - 11152
      Abstract: The LLC resonant converter is popular but needs a discrete series resonant inductor and a capacitor. In order to cut down component count, a novel multilayer flexible printed circuitry (FPC) planar transformer with integrated series capacitance and inductance is proposed in this paper. This planar transformer consists of two sets of multilayer open-ended windings coupled with each other to produce the integrated resonant capacitor. The equivalent resonant capacitance can be controlled by the number of the layers without changing the number of primary winding turns or pattern. The proposed transformer successfully integrates the resonant capacitor and the resonant inductor, into a single component. A model is established to accurately predict the equivalent series resonant capacitance of the transformer from the physical structure. Several multilayer FPC planar transformers are built to test the model. Practical measurements and theoretical results show good agreement and validate the proposed model. Finally, an LLC power converter with 94% efficiency is built to demonstrate the proper functioning of the proposed multilayer FPC planar transformer.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • An Improved Stray Capacitance Model for Inductors
    • Authors: Zhan Shen;Huai Wang;Yanfeng Shen;Zian Qin;Frede Blaabjerg;
      Pages: 11153 - 11170
      Abstract: This paper proposes an improved analytical stray capacitance model for inductors. It considers the capacitances between the winding and the central limb, side limb, and yoke of the core. The latter two account for a significant proportion of the total capacitance with the increase of the core window utilization factor. The potential of the floating core/shield is derived analytically, which enables the model to apply not only for the grounded core/shield, but also for the floating core/shield cases. On the basis of the improved model, an analytical optimization method for the stray capacitance in inductors is proposed. Moreover, a global Pareto optimization is carried out to identify the tradeoffs between the stray capacitance and ac resistance in the winding design. Finally, the analysis and design are verified by finite element method simulations and experimental results on a 100-kHz dual active bridge converter.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Interferences in AC–DC LED Drivers Exposed to Voltage Disturbances in
           the Frequency Range 2–150 kHz
    • Authors: Selcuk Sakar;Sarah Rönnberg;Math Bollen;
      Pages: 11171 - 11181
      Abstract: LED lamps are both potential victims and sources of electromagnetic disturbances in the frequency range between 2 and 150 kHz (“supraharmonics”). Immunity tests for this frequency range are important due to possible performance degradation of light intensity with LED lamps. In this paper, the impact of supraharmonics (SHs) on light intensity from LED lamps has been analyzed. LED lamps have been exposed to SH test profiles based on IEC 61000-4-19. Three phenomena that impact light intensity metrics have been observed and explained by models: 1) earlier conduction/later blocking caused by SH voltage, 2) intermittent conduction depending on the SH impedance of the LED driver, and 3) reverse-recovery current of the diodes at higher frequency. It is observed that impact on the light intensity metrics shows up around the beginning and end of the conduction period. The results reveal that the profile of the SH voltage could cause deviations in the modulation depth and the average light intensity. The immunity of LED lamps against SHs shall be further studied and discussed by research groups and standard committees.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Implications of Ageing Through Power Cycling on the Short-Circuit
           Robustness of 1.2-kV SiC mosfets
    • Authors: Paula Diaz Reigosa;Haoze Luo;Francesco Iannuzzo;
      Pages: 11182 - 11190
      Abstract: In this paper, the reliability performance of 1.2-kV silicon carbide (SiC) power mosfet modules is investigated through the combination of both accelerated power-cycling tests and short-circuit tests. The short-circuit robustness of SiC mosfet is investigated after stressing the dies under power-cycling tests. In this way, the implications of different levels of degradation on the short-circuit capability can be better understood. During the power-cycling tests, some electrical parameters, either related to the package or the die, may experience variations as a consequence of the device ageing (e.g., increase in bond wire resistance and increase in gate leakage current). The effect of these parameter variations on the short-circuit withstanding capability of SiC mosfets is investigated for the first time in this paper. The proposed method helps to understand which degradation effects under normal operation have a major implication on the short-circuit robustness, which gives a more realistic information about the root cause of the failures observed in the field.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • An Integrated SiC CMOS Gate Driver for Power Module Integration
    • Authors: Matthew Barlow;Shamim Ahmed;A. Matt Francis;H. Alan Mantooth;
      Pages: 11191 - 11198
      Abstract: With high-temperature power devices available, the support circuitry required for efficient operation, such as a gate driver, is needed as part of a complete high-temperature solution. The design of an integrated silicon carbide (SiC) gate driver using a 1.2-μm complementary metal–oxide–semiconductor (CMOS) process is presented. Adjustable drive strength is added to facilitate a minimal external component requirement for high-temperature power modules and lays the groundwork for dynamic adjustment of drive strength. The adjustable drive strength feature demonstrates a capability of reducing overshoot and controlling dv/dt dynamically. Measurement of the gate driver was performed driving a power mosfet gate over temperature, exceeding 500 °C. High-speed and high-voltage room temperature evaluation is provided, demonstrating a system capable of high performance over temperature. The driver accomplishes better than 75 ns of rise and fall time driving the Cree CPM3-0900-0065B from room temperature to over 500 °C indicating that it will be ideal for integration into an all-SiC power module where driver, protection circuits, and power devices are fabricated in SiC.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Layout-Dominated Dynamic Current Imbalance in Multichip Power Module:
           Mechanism Modeling and Comparative Evaluation
    • Authors: Zheng Zeng;Xin Zhang;Xiaoling Li;
      Pages: 11199 - 11214
      Abstract: The multichip power module is an irreplaceable component for high-capacity industrial converters. Dynamic current imbalance among parallel chips challenges the electrothermal stability and limits the maximum current rating of the power module. In this paper, general mechanism models are proposed to reveal the layout-dominated dynamic current imbalance in the multichip power module. The influence of the layout on the current sharing is comparatively evaluated by power modules with and without Kelvin connections. Focusing on the dynamic current imbalance, based on a commercial multichip power module, finite-element analysis and equivalent electric circuit are utilized to illustrate the impact of Kelvin connection. General mathematical and graphical models are created to address the current sharing of parallel chips affected by networked parasitic impedances. Based on the fabricated power module prototypes, extensive experiments and detailed analyses are presented concerning the current sharing, transient time, and switching loss. It is demonstrated that the Kelvin connection can elevate switching speed and reduce switching loss of parallel chips, while its functionality to eliminate dynamic current imbalance depends on the parasitic impedances. Some general design guidelines of the multichip power module are presented for current sharing. To achieve satisfactory current sharing, advanced packaging layout by using the optimized chip arrangement and wire interconnection is further needed for the multichip power module.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Fault-Tolerant Back-to-Back Converter for Direct-Drive PMSG Wind Turbines
           Using Direct Torque and Power Control Techniques
    • Authors: Imed Jlassi;Antonio J. Marques Cardoso;
      Pages: 11215 - 11227
      Abstract: Fault tolerance in wind turbines is considered crucial to increase their reliability and availability levels. This paper presents a fault-tolerant direct-drive permanent magnet synchronous generator (PMSG) using new direct control techniques, with the ability to handle power semiconductor open-circuit faults in the full-scale back-to-back converter. The fault-tolerant topology consists of a five-leg converter, with a shared leg connected to a generator phase and to its corresponding grid phase, through a triode for alternating current (TRIAC). The main contribution of this paper consists of the development of an alternative direct torque control and direct power control schemes for both machine-side converter and grid-side converter, respectively. Moreover, a reliable fault diagnostics algorithm without requiring additional sensors is also integrated, providing the information required to instantaneously trigger fault-tolerant remedial strategies. Simulation and experimental results are presented to validate the effectiveness of the proposed fault-tolerant PMSG drive.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • IGBT Power Stack Integrity Assessment Method for High-Power Magnet
    • Authors: Panagiotis Asimakopoulos;Konstantinos Papastergiou;Torbjörn Thiringer;Massimo Bongiorno;Gilles Le Godec;
      Pages: 11228 - 11240
      Abstract: This paper proposes a method for assessing the integrity of a series of insulated-gate bipolar transistor (IGBT) power stacks during factory-acceptance tests and service stops. The key challenge that is addressed in this paper is detecting common assembly issues that affect the power stack thermal path as well as distinguishing the acute aging effects of bond-wire lift-off and solder delamination. The method combines offline ${V_{boldsymbol{ce}}}$ measurements with current in the extended Zero Temperature Coefficient (ZTC) operating region as well as with sensing current without modifications to the power stack. It also employs on-the-stack ${V_{boldsymbol{ce}}} $ calibration for both the measurements. Additionally, only a fixed duty cycle pattern is needed to control the switches. The paper also presents a sensitivity analysis of the method to various parameters such as the current level in the extended ZTC operating region, the precision of the ${V_{boldsymbol{ce}}}$ measurement, as well as the ambient, the cooling-water, and the junction temperatures. The experimental results are obtained from a high-current IGBT power stack used in a magnet power supply for particle accelerators and are compared favorably to results from finite element method and lumped parameter network simulations confirming the applicability of the method.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Detection and Localization of Open-Phase Fault in Three-Phase Induction
           Motor Drives Using Second Order Rotational Park Transformation
    • Authors: Ali Hajary;Reza Kianinezhad;S.Gh Seifossadat;S.S Mortazavi;Alireza Saffarian;
      Pages: 11241 - 11252
      Abstract: The open-phase fault in vector-controlled drives is known as one of the most prevalent failures that require immediate detection. It is still challenging to develop a trustable fault diagnosis scheme at light load, transients, and low-speed regions. This paper presents a novel open-phase fault diagnosis strategy for three-phase induction motor drives over the entire speed range and for different load conditions. By taking advantage of the second-order rotational park transformation (SORP), new fault indices are proposed to identify the open-phase location without using any additional sensors or electric equipment. Comparing with root-mean-square (RMS) calculation-based methods, the proposed method detects the fault at least twice faster, with minimal system resources. The presented scheme may be implemented simply and is robust against the operating point changes. Proof of the proposed fault detection and localization method has been shown through experimental tests on a 250-W three-phase induction machine which is controlled by TI-DSP F28335.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Investigation of PM Eddy Current Losses in Surface-Mounted PM Motors
           Caused by PWM
    • Authors: Jing Ou;Yingzhen Liu;Dawei Liang;Martin Doppelbauer;
      Pages: 11253 - 11263
      Abstract: It is well known that spatial field harmonics will cause high eddy current losses in surface-mounted permanent magnets (PMs) especially for the fractional-slot PM motors. However, the influence of temporal current harmonics, especially of the high-order temporal harmonics caused by pulsewidth modulation voltages from an inverter, lacks attentions. This paper studies the eddy current losses of the PMs caused by high-order current harmonics. In order to simplify the calculation and save computation time, analytical methods are used to predict the current harmonics caused by the PWM inverter, and the armature reaction field, the eddy current density, and losses in the PMs generated by the current harmonics. Finite element analysis, coupling simulation, and experimental studies are used to verify the analytical results. The study results show that the high-order current harmonics cause much higher eddy current losses than those caused by slotting and fundamental current even though the amplitudes of the high-order current harmonics are much lower.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • $dtext{--}q$ +Domain+Based+Power+Line+Signaling+Technique+for+Power+Converters+in+a+Microgrid&rft.title=IEEE+Transactions+on+Power+Electronics&rft.issn=0885-8993&;&rft.aufirst=S.&;Loganathan+Umanand;">A Novel Fractional Harmonic $dtext{--}q$ Domain Based Power Line Signaling
           Technique for Power Converters in a Microgrid
    • Authors: S. Shan;Loganathan Umanand;
      Pages: 11264 - 11277
      Abstract: Traditionally, the communication between power converters connected in a microgrid is established using a wired method or a wireless droop method. The shortcomings of these methods have opened up the possibility of power-line-based communication between converters. However, the conventional power line communication systems have the disadvantages of using high-frequency data carrying signals that are prone to attenuation. These systems also make use of explicit couplers, transmitters, and amplifiers that adds to the overall cost and infrastructure. In this paper, a novel fractional harmonic $dtext{--}q$ domain based power line communication technique is proposed. A switched fractional harmonic current space vector is used to carry data. The primary control loop and the modulation algorithm of the converters are used for encoding and decoding of data. The proposed technique thus overcomes the disadvantages of the conventional power line communication systems and at the same time carries forward the advantages of it. The proposed technique is validated with sufficient experimental test results.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Robust Control of Three-Phase Voltage Source Converters Under Unbalanced
           Grid Conditions
    • Authors: Houshang Karimi;Masoud Karimi-Ghartemani;Keyhan Sheshyekani;
      Pages: 11278 - 11289
      Abstract: This paper proposes a new and robust control strategy for distributed energy resource (DER) units operating in parallel with a three-phase ac grid that could have unbalance voltages. It is well known that the grid imbalance imposes double-frequency ripples on the dc-side capacitor and low-order harmonics on the ac side of a voltage source converter widely used to interface the DERs with the grid. The proposed controller is able to overcome both problems. This not only improves the power quality and stability aspects of the DER and overall system, but will also help reduce the size of the dc-side capacitor. The proposed controller belongs to the family of current controllers and can in principle be added as an upgrade to the existing current controllers. Mathematical analysis and optimal control design aspects are presented and then the performance of the proposed controller is evaluated by various simulation scenarios and hardware-in-the-loop experiments.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Bi-Directional Grid-Connected Modular Multilevel Converters With Direct
           Digital Control and D-Σ Processes
    • Authors: Tsai-Fu Wu;Tzu-Chieh Chou;Chun-Wei Huang;Kai Sun;
      Pages: 11290 - 11299
      Abstract: This paper presents bidirectional grid-connected modular multilevel converters (MMC) with direct digital control and division-summation processes to achieve power-injection and rectification functions. A direct digital control is developed to track current references, regulate dc-bus voltage and cell voltage, and balance the upper and lower dc-bus voltages. It can accommodate wide filter-inductance variation and take care of source voltage harmonics to achieve tight current tracking and low distortion output current. Based on the power-balance principle, the commands of arm currents can be determined directly. In this paper, the MMC configuration is introduced first, and then the control laws for current tracking and voltage regulation are derived in detail. Experimental and simulated results obtained from two 50 kW MMCs operated in power-injection and rectification modes have verified the analysis and discussion.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Robust Non-Fragile Fuzzy Control of Uncertain DC Microgrids Feeding
           Constant Power Loads
    • Authors: Navid Vafamand;Mohammad Hassan Khooban;Tomislav Dragičević;Frede Blaabjerg;Jalil Boudjadar;
      Pages: 11300 - 11308
      Abstract: This paper investigates the problem of dynamic stabilization of dc microgrids (MGs) through a robust non-fragile fuzzy control synthesis of power buffer. The suggested robust fuzzy controller is designed to quickly stabilize the MGs by circulating the power between the dc link and an energy storage system (ESS). By employing the exponential stability analysis and Takagi–Sugeno fuzzy modeling, sufficient controller design conditions are derived in terms of linear matrix inequalities, which bring about a simple, systematic, and effective controller. The proposed approach is resilient against the uncertainties of the dc MG and ESS parameters. To show the merits of the proposed approach, it is applied to a dc MG that feeds one constant power load. It is shown that the proposed approach is more robust against system and controller uncertainties compared to the existing results. Finally, experimental results are then presented that show the transient performance improvement of the closed-loop system compared to the state-of-the-art methods.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Robust Stability Analysis of Synchronverters Operating in Parallel
    • Authors: Roberto Rosso;Soenke Engelken;Marco Liserre;
      Pages: 11309 - 11319
      Abstract: Recent studies have shown how synchronization units of converters operating nearby may interact with each other, affecting the stability of the system. Synchronverters are able to self-synchronize to the grid without the need of a dedicated unit because they can reproduce the power synchronization mechanism of synchronous machines. Recently, the robust stability of a synchronverter has been investigated by means of structured singular values (commonly called $mu$-analysis). In this paper, $mu$-analysis is performed to investigate how the robust stability of a synchronverter is affected by the presence of another converter of the same type operating in parallel. It is demonstrated that the parallel operation of synchronverters reduces their robust stability and a possible solution is proposed, based on the implementation of virtual impedances in the control algorithm. An accurate state-space model of the system under study is developed by adopting the component connection method and the robust stability analysis is validated against time-domain simulations in MATLAB/Simulink/PLECS and experimental results with a power-hardware-in-the-loop test bench.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • High-Bandwidth Secondary Voltage and Frequency Control of VSC-Based AC
    • Authors: Rasool Heydari;Tomislav Dragicevic;Frede Blaabjerg;
      Pages: 11320 - 11331
      Abstract: This paper proposes a novel secondary control strategy for the power-electronic-based ac microgrid. This approach restores the voltage and frequency deviations by utilizing only local variables with very high bandwidth. This is realized with a finite control set model predictive control technique that is adopted in the inner level of the primary control of voltage source converters. In the outer level of the primary control, droop control and virtual impedance loops are exploited to adjust the power sharing among different distributed generation (DGs). As inner control level operates with a very high bandwidth, need for filtering of the calculated active and reactive powers in the outer level of the primary control is insignificant. Therefore, the secondary control can be operated with a far superior bandwidth compared to the case when the conventional cascaded linear control is used. Merits of the proposed approach are investigated analytically with the help of the describing function methodology that allows the quasi-linear approximation of the inner control level. Finally, simulation and experimental results are presented.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Transfverter: Imbuing Transformer-Like Properties in an Interlink
           Converter for Robust Control of a Hybrid AC–DC Microgrid
    • Authors: Yunjie Gu;Yitong Li;Hyeong-Jun Yoo;Thai-Thanh Nguyen;Xin Xiang;Hak-Man Kim;Adria Junyent-Ferre;Timothy C. Green;
      Pages: 11332 - 11341
      Abstract: In a hybrid ac–dc microgrid, stiff voltage sources may appear in either the dc or ac subgrids, which gives rise to multiple operation modes as power dispatch changes. This creates a challenge for designing the interlink converter between the ac and dc subgrids, since the different modes require different interlink controls. To solve this problem, this paper proposes the concept of a transfverter inspired by how transformers link ac grids. Like a transformer, a transfverter can react to the presence of stiff voltage sources on either the dc or ac side and reflect the “stiffness” and voltage stabilizing capability to the other side. A back-to-back converter with droop control is used as the underlying technology to implement this concept. A novel optimization method called model bank synthesis is proposed to find control parameters for the interlink converter that offer the best controller performance across the different microgrid modes without requiring mode changing of the controller. The effectiveness of the proposed solution is validated through both simulation and experiments.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A Conservatism-Free Large Signal Stability Analysis Method for DC
           Microgrid Based on Mixed Potential Theory
    • Authors: Jianbo Jiang;Fei Liu;Shangzhi Pan;Xiaoming Zha;Wenjun Liu;Chao Chen;Lidong Hao;
      Pages: 11342 - 11351
      Abstract: Large disturbance scenarios, such as pulse power load operation and load switching are commonly seen in the operation of dc microgrids. The mixed potential theory-based large-signal stability (LSS) analysis is a simple and practical method for investigating the LSS of dc microgrids. However, this method is characterized by conservatism, and produces conservative stability criterion results. When they are applied to the parameter designs of dc microgrids, they create excessive control parameter redundancies; when used for running status estimations, they may cause the system to be misjudged as unstable, and trigger unnecessary protective actions when the system runs into the conservative region. This paper presents a comprehensive analysis of the conservatism, revealing its main causes to be the idealization of the load converter's response characteristics, and the lack of refined models. It then proposes a novel, improved analysis method for transient response characteristics of the load converter. Experimental and simulation results using the improved method have validated it by showing that the conservatism of the traditional method had been eliminated, and the stability criterion obtained was more accurate.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Loop Shaping by Single-Resonant Controllers for Prescribed Tracking of
           Sinusoidal References
    • Authors: Moria Elkayam;Sergei Kolesnik;Yeshialeka Basha;Alon Kuperman;
      Pages: 11352 - 11360
      Abstract: It is well-known that in ac-grid-connected or motor-driving converters, current behavior directly sets the exchange of power between the two. Moreover, in corresponding current plants, most of the disturbance (formed by grid voltage or back EMF and the dc-link voltage) may be measured/estimated and appropriately canceled, reducing the current regulation problem to tracking challenge only. The latter is still of extreme importance since the amount of active/reactive power exchanged is proportional to current magnitude and phase. Recently, a method for deriving proportional-resonant controller structure and coefficients according to desired tracking behavior of ac signal amplitude, applied to typical power converter current loop, was proposed based on the fact that if ac signal envelope is perceived as dc signal, its transient behavior may be easily shaped utilizing well-known approaches employed in dc systems loop shaping while keeping zero phase tracking error at all time. This paper extends the proposed methodology by introducing in-depth analysis of the resulting loop gain shaping, applying practical issues, such as actuator delay, damping, and finite word length to the system, yielding a closed set of hands-on design guidelines. Experimental results are also given, providing a two-fold value: successfully validating the presented material and demonstrating that some of the previously reported outcomes (based on simulations) cannot be achieved in practice due to the above mentioned real world constraints.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Dynamic Phasor-Based Reduced-Order Models of Wireless Power Transfer
    • Authors: Hongchang Li;Jingyang Fang;Yi Tang;
      Pages: 11361 - 11370
      Abstract: Wireless power transfer (WPT) systems in dynamical applications, such as roadway-powered electrical vehicles, require dynamical models for the analysis and control. Conventional modeling methods for WPT systems lead to high-order models as each resonant voltage or current is described by two slowly varying real-valued variables. Other modeling methods may reduce the order but suffer from disadvantages, such as the lack of analytical expressions, loss of generality, and incomplete modeling. This paper develops a systematic and intuitive modeling approach using time-domain dynamic phasors and proposes reduced-order models by applying appropriate s-domain approximations to the linear parts of the system. A dual-side pulse-density-modulation WPT system is completely modeled as an example. Both the equivalent circuits and the mathematical descriptions are presented. The derived models are verified by large-signal step responses and small-signal frequency responses measured during experiments. As compared with the full-order models, the proposed reduced-order models have much more concise formulae while retaining high accuracy.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Overload and Short-Circuit Protection Strategy for Voltage Source
           Inverter-Based UPS
    • Authors: Baoze Wei;Albert Marzàbal;José Perez;Ramon Pinyol;Josep M. Guerrero;Juan C. Vásquez;
      Pages: 11371 - 11382
      Abstract: In this paper, an overload and short-circuit protection method is proposed for voltage source inverter-based uninterruptible power supply (UPS) system. In order to achieve high reliability and availability of the UPS, short circuit and overload protection scheme are necessary. When overload or short circuit happens, using the proposed control method, the amplitude of the output current can be limited to a constant value, which can be set by the customer to avoid the destruction of the power converter, and to obtain a faster recovery performance as well. The detailed principle of the proposed protection method is discussed in this paper. It mainly contains three parts in the control diagram for current limit, first is the anti-windup in the voltage and current controllers, then the feedforward of the capacitor voltage to the current control loop, the last is the fast reset of the resonant part of the current controller when overcurrent happens. The procedure of developing the control method is also presented in the paper. Experimental results on a commercial UPS system are presented to verify the effectiveness of the control method.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Voltage-Modulated Direct Power Control for a Weak Grid-Connected Voltage
           Source Inverters
    • Authors: Yonghao Gui;Xiongfei Wang;Heng Wu;Frede Blaabjerg;
      Pages: 11383 - 11395
      Abstract: In this paper, we design a voltage-modulated direct power control (VM-DPC) for a three-phase voltage source inverter (VSI) connected to a weak grid, where the phase-locked loop (PLL) system may make the system unstable if the conventional vector current control (VCC) method is applied. Compared with the conventional VCC method, the main advantage of the proposed VM-DPC method is that the PLL system is eliminated. Moreover, in order to inject the rated real power to the weak grid, the VSI system should generate some certain amount of reactive power as well. An eigenvalues-based analysis shows that the system with the proposed method tracks its desired dynamics in the certain operating range. Both simulation and experimental results match the theoretical expectations closely.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • An Improved Design Methodology of the Double-Sided LC-Compensated CPT
           System Considering the Inductance Detuning
    • Authors: Hua Zhang;Fei Lu;
      Pages: 11396 - 11406
      Abstract: This paper proposes an improved design methodology of the double-sided LC-compensated capacitive power transfer (CPT) system considering the inductance detuning. Compared to the perfect-resonant scenario, this paper shows that the inductance detuning has the benefit to achieve the soft-switching condition for the CPT system, and the output current and internal voltage stresses can also be maintained within the desired range. The contributions of this paper are summarized in three parts. First, it analyzes the impacts of the inductance variations on the system frequency property, including the input current, output current, and internal capacitor voltage stresses. Second, it proposes three principles to detune the inductances as the methodology to design a CPT system. Third, a prototype is implemented, which achieves 368.5 W power transfer across a 400 mm × 400 mm × 4 mm glass layer with 91.8% dc–dc efficiency. Experimental results validate that the proposed design principles are satisfied, showing that the output current is within the desired range, the input soft-switching condition is achieved, and the internal voltage stresses are within the safety limit. Moreover, the efficiency and frequency properties are also validated by the experimental results, showing a wide power range of the high-efficiency operation (higher than 90%) and a wide frequency bandwidth of the soft-switching operation (from 0.96 to 1.12 MHz).
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Two-Dimensional Impedance-Shaping Control With Enhanced Harmonic Power
           Sharing for Inverter-Based Microgrids
    • Authors: Yang Qi;Pengfeng Lin;Yu Wang;Yi Tang;
      Pages: 11407 - 11418
      Abstract: In islanded microgrids, the harmonic power of nonlinear loads is distributed among parallel voltage source inverters (VSIs) according to the effective harmonic impedances, i.e., the sums of VSI output impedances and grid impedances. Since grid impedances are unknown and could be mismatched, VSI output impedances are usually reshaped to ensure the harmonic power sharing accuracy. However, as conventional techniques only regulate VSI output impedances in one dimension, only one degree of freedom is provided for the impedance shaping. It is revealed that such maneuvers can hardly fulfill the proper harmonic power sharing requirement under complex grid impedance situations. As a result, circulating harmonic currents will occur and produce additional power losses even if the total harmonic power has been accurately shared. To solve this problem, this paper proposes a two-dimensional impedance-shaping control, which can adaptively regulate VSI output resistances and inductances at the same time. The proposed control strategy requires no prior grid impedance knowledge and can eliminate the circulating harmonic currents for arbitrary grid impedances. Simulation and experimental results from an islanding microgrid prototype with three parallel VSIs are provided to validate the effectiveness of the proposed method.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • A Modified Double Vectors Model Predictive Torque Control of Permanent
           Magnet Synchronous Motor
    • Authors: Wei Chen;Sike Zeng;Guozheng Zhang;Tingna Shi;Changliang Xia;
      Pages: 11419 - 11428
      Abstract: Duty cycle model predictive torque control (Duty-MPTC) only uses zero vector as the second vector to form vector combinations, which restricts its torque control performance. This paper proposes a modified double vectors model predictive torque control (DVMPTC) by reasonably selecting active vector instead of zero vector. By analyzing the regulation of torque and flux of permanent magnet synchronous motor (PMSM), the torque and flux difference parameters are obtained, and then a second vector selection table is established to determine the best vector combination for torque ripple suppression. Based on the torque and flux difference parameters, the duty cycle calculation method is proposed to reduce the calculation burden of the control system. In order to verify the effectiveness of the proposed method, experiments with a 6-kW PMSM are carried out. Compared to the Duty-MPTC, the proposed DVMPTC method can significantly reduce the torque ripples with good dynamic performance and relatively low average switching frequency.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Active Voltage Balancing in Flying Capacitor Multi-Level Converters With
           Valley Current Detection and Constant Effective Duty Cycle Control
    • Authors: Andrew Stillwell;Enver Candan;Robert C. N. Pilawa-Podgurski;
      Pages: 11429 - 11441
      Abstract: One of the challenges of utilizing flying capacitor multi-level (FCML) converters is the flying capacitor balancing. Poorly balanced flying capacitors increase the switch voltage stress, which is detrimental to performance and device rating requirements. Previously, valley current detection was shown as a potential method to balance flying capacitors, but the method suffers from poor flying capacitor balancing performance at light load. Here, we investigate the light load conditions that lead to poor balancing and propose a new method, constant effective duty cycle (CEDC) compensation, which provides active balancing for the full load range of the converter. The proposed method is validated with a 4-level FCML experimental prototype, demonstrating excellent flying capacitor balancing over all load ranges, across the full duty cycles range and with multiple induced flying capacitor imbalances.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Energy and Size Reduction of Grid-Interfaced Energy Buffers Through Line
           Waveform Control
    • Authors: Alex J. Hanson;Andreea F. Martin;David J. Perreault;
      Pages: 11442 - 11453
      Abstract: Grid-interface converters with power factor correction (PFC) generally require large energy buffer capacitors to maintain a constant power output. These buffer capacitors can occupy 20%–30% of total system volume, and their size is unaffected by typical methods of miniaturizing power converters such as increasing efficiency or changing switching frequency. Here, we investigate an approach in which harmonic current is intentionally drawn from the grid (within allowed regulations) to reduce the required energy storage. We show that this method can substantially reduce the energy storage requirement under every IEC/EN 61000-3-2 regulation class, including Class A ($>$60% reduction), Class B ($>$80%), Class C $>$25 W ($>$25%), Class C $leq$ 25 W ($>$70%), and Class D (62%). This benefit can generally be achieved solely through controls without additional hardware and can be applied across PFC converter topologies. A valley-switched boost PFC converter is used to validate that harmonic injection achieves the calculated energy storage reduction with little impact on efficiency. We also show that, for a variable-frequency PFC, the proposed approach beneficially compresses the switching frequency range. This technique, thus, provides a high-impact, low-cost approach to miniat-rizing the energy buffer in grid-interface power converters.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Stable Operation Method for Speed Sensorless Induction Motor Drives at
           Zero Synchronous Speed With Estimated Speed Error Compensation
    • Authors: Wei Sun;Zhenyu Wang;Dianguo Xu;Xuechu Yu;Dong Jiang;
      Pages: 11454 - 11466
      Abstract: The methodologies applied to speed sensorless induction motor drives (SSIMD) can be divided into two categories. The first category makes use of the fundamental model of induction motor to establish speed and flux observers. However, the rotor speed is unobservable with these methods when synchronous speed is close to zero. The second category makes use of anisotropies of induction motor to observe rotor speed. However, the anisotropies of induction motor are too weak to extract rotor speed information. Consequently, the unstable problem of SSIMD at low synchronous speed (including zero synchronous speed) has not been solved yet by now. In this paper, a virtual voltage injection method is proposed to solve this problem. The voltage is only injected into observer. The observability of rotor speed based on proposed virtual voltage injection is analyzed. Because the injected voltage into observer results in estimated speed error, a compensation method is proposed then. The stability of the system with virtual voltage injection and corresponding compensation method is analyzed by the input-state-stability concept. Finally, the feasibility of the proposed method is verified by experiments.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Disturbance-Observer-Based PBC for Static Synchronous Compensator Under
           System Disturbances
    • Authors: Jinmu Lai;Xin Yin;Lin Jiang;Xianggen Yin;Zhen Wang;Zia Ullah;
      Pages: 11467 - 11481
      Abstract: Passivity-based control (PBC) relies on an accurate mathematical model and thus its performance will be degraded by the weak robustness against parameters uncertainties, modeling error, and external disturbances. Moreover, it cannot achieve zero tracking error of the steady-state current under parameter uncertainties and modeling error. This paper proposes a novel disturbance-observer- (DO) based PBC (DO-PBC) for static synchronous compensator (STATCOM) to achieve better stability and dynamic performances against disturbances. A DO that has been introduced into the PBC current loop is used to compensate system disturbances, which can improve the robustness of the control system and eliminate the steady-state tracking error. Moreover, the proposed DO-PBC provides faster responses in handling various kinds of disturbances. Then, the detail design process, stability and robustness analysis, and parameters tuning method are investigated and presented. Also, the proposed method is simple to be implemented by the separation principle. The performance comparisons among the proportional integral, the conventional PBC, and the proposed DO-PBC are carried out to show the effectiveness of the proposed method against disturbances and the precise current tracking, via simulation tests and experimental tests based on a down-scale laboratory prototype experiment of 380 V STATCOM.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Eigenvalue Optimization of the Energy-Balancing Feedback for Modular
           Multilevel Converters
    • Authors: Hendrik Fehr;Albrecht Gensior;
      Pages: 11482 - 11495
      Abstract: Despite its potential impact on the balancing performance, current literature on the modular multilevel converter (MMC) energy-balancing feedback gain design and tuning process seem incomplete. In order to close this research gap, the energy-balancing feedback gain tuning of an ac current controlled MMC with half-bridge cells and isolated star point is considered in this paper. The tuning is difficult, because each energy error adds its own dedicated component to the circulating current reference that leads to a strong coupling that evades common tuning approaches. This problem is solved in two steps: at first, the relevant error dynamics is extracted and validated to model the time domain behavior of the energy balancing. Second, a theorem from Wu (1975) is invoked to easily calculate the closed-loop eigenvalues that finally allow for an easy optimization of the energy-balancing performance. Despite the radical simplifications during the modeling and error dynamics extraction, the acquired model is able to adequately reproduce the energy errors and the balancing circulating current of the converter. Simulation and measurement results on a grid-side MMC demonstrate a considerable performance improvement in contrast to the traditional gain estimation on the open loop. This is verified with and without a second harmonic in the circulating currents.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
  • Advanced Energy Flow Control Concept of an MMC for Unrestricted Operation
           as a Multiport Device
    • Authors: Markus Schroeder;Johann Jaeger;
      Pages: 11496 - 11512
      Abstract: An advanced approach of the internal energy flow control of a multiport device based on a modular multilevel converter (MMC) was proposed. Such a multiport device offers various connecting points as ac terminals, the main dc terminal as well as the dc terminals of the MMC modules. State-of-the-art multiport concepts have restrictions concerning the flexibility of connecting the available ports. The proposed concept makes an unrestricted energy interchange between all ports possible without affecting the ac grid and the main dc terminal. It contains a microscopic and macroscopic view of the entire system and an analytic description in a double synchronous reference frame. This approach allows the identification of degrees of freedom for the internal energy flow control to overcome the mentioned restrictions of state-of-the-art multiport devices. Beyond numerous simulations calculations, the proposed concept has been implemented to a prototype of a multiport device which consists of an MMC with integrated batteries in power electronics laboratory. The approach has been successfully tested and verified with measurement results.
      PubDate: Nov. 2019
      Issue No: Vol. 34, No. 11 (2019)
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