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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Power Electronics
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Journal DOI :
The Korean Institute of Power Electronics
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Volume & Issues
Volume 13, Issue 6 - Nov 2013
Volume 13, Issue 5 - Sep 2013
Volume 13, Issue 4 - Jul 2013
Volume 13, Issue 3 - May 2013
Volume 13, Issue 2 - Mar 2013
Volume 13, Issue 1 - Jan 2013
Selecting the target year
Analysis of the Charging Characteristics of High Voltage Capacitor Chargers Considering the Transformer Stray Capacitance
Lee, Byungha ; Cha, Hanju ;
Journal of Power Electronics, volume 13, issue 3, 2013, Pages 329~338
DOI : 10.6113/JPE.2013.13.3.329
In this paper, the charging characteristics of series resonant type high voltage capacitor chargers considering the transformer stray capacitance have been studied. The principles of operation for the four operational modes and the mode changes for the four different switching frequency sections are explained and analyzed in the range of switching frequency below the resonant frequency. It is confirmed that the average charging currents derived from the above analysis results have non-linear characteristics in each of the four modes. The resonant current, resonant voltage, charging current, and charging time of this capacitor charger as variations of the switching frequency, series parallel capacitance ratio (
), and output voltage are calculated. From the calculation results, the advantages and disadvantages arising from the parallel connection of this stray capacitance are described. Some methods to minimize charging time of this capacitor charger are suggested. In addition, the results of a comparative test using two transformers whose stray capacitances are different are described. A 1.8 kJ/s prototype capacitor charger is assembled with a TI28335 DSP controller and a 40 kJ, 7 kV capacitor. The analysis results are verified by the experiment.
Analysis and Design of Coupled Inductors for Two-Phase Interleaved DC-DC Converters
Lee, Jong-Pil ; Cha, Honnyong ; Shin, Dongsul ; Lee, Kyoung-Jun ; Yoo, Dong-Wook ; Yoo, Ji-Yoon ;
Journal of Power Electronics, volume 13, issue 3, 2013, Pages 339~348
DOI : 10.6113/JPE.2013.13.3.339
Multiphase dc-dc converters are widely used in modern power electronics applications due to their advantages over single-phase converters. Such advantages include reduced current stress in both the switching devices and passive elements, reduced output current ripple, and so on. Although the output current ripple of a converter can be significantly reduced by virtue of the interleaving effect, the inductor current ripple cannot be reduced even with the interleaving PWM method. One way to solve this problem is to use a coupled inductor. However, care must be taken in designing the coupled inductor to maximize its performances. In this paper, a detailed analysis of a coupled inductor is conducted and the effect of a coupled inductor on current ripple reduction is investigated extensively. From this analysis, a UU core based coupled inductor structure is proposed to maximize the performance of the coupled inductor.
The Effect of Transformer Leakage Inductance on the Steady State Performance of Push-pull based Converter with Continuous Current
Chen, Qian ; Zheng, Trillion Q. ; Li, Yan ; Shao, Tiancong ;
Journal of Power Electronics, volume 13, issue 3, 2013, Pages 349~361
DOI : 10.6113/JPE.2013.13.3.349
As a result of the advantages such as high efficiency, continuous current and high stability margin, push-pull converter with continuous current (PPCWCC) is competitive for battery discharge regulator (BDR) which plays an important role in power conditioning unit (PCU). Leakage inductance yields current spike in low-ripple current of PPCWCCs. The operating modes are added due to leakage inductance. Therefore the steady state performance is affected, which is embodied in the spike of low-ripple current. PPCWCCs which are suitable for BDR can be separated into three types by current spike characteristics. Three representative topologies IIs1, IIcb2 and Is3 are analyzed in order to investigate the factors on the magnitude and duration of spike. Equivalent current sampling method (ECSM) which eliminates the sampling time delay and achieves excellent dynamic performance is adopted to prevent the spike disturbance on current sampling. However, ECSM reduces the sampling accuracy and telemetry accuracy due to neglecting the spike. In this paper, ECSM used in PPCWCCs is summarized. The current sampling error is analyzed in quality and quantity, which provides the foundation for offsetting and enhancing the telemetry accuracy. Finally, current sampling error rate of three topologies is compared by experiment results, which verify the theoretical analysis.
Cost-effective Power System with an Electronic Double Layer Capacitor for Reducing the Standby Power Consumption of Consumer Electronic Devices
Park, Kyung-Hwa ; Yi, Kang-Hyun ;
Journal of Power Electronics, volume 13, issue 3, 2013, Pages 362~368
DOI : 10.6113/JPE.2013.13.3.362
Commercial home appliances using remotely controlled systems consume electric power while in standby mode to prepare for receiving a remote turn-on signal. The proposed power system can significantly reduce standby power consumption without increasing cost. Furthermore, since a Electronic Double Layer Capacitor (EDLC) is used as an auxiliary power storage element, the life cycle is longer and system reliability can be better than with existing approaches. When the energy of the EDLC is not sufficient for turning on the appliance, the power system charges the EDLC without affecting the main system. The proposed power system is verified with a commercial LCD TV and a 3.93mW standby consumption is obtained. This standby consumption can be regarded as zero standby equipment according to the IEC-62031 standard.
Modified Direct Torque Control using Algorithm Control of Stator Flux Estimation and Space Vector Modulation Based on Fuzzy Logic Control for Achieving High Performance from Induction Motors
Rashag, Hassan Farhan ; Koh, S.P. ; Abdalla, Ahmed N. ; Tan, Nadia M.L. ; Chong, K.H. ;
Journal of Power Electronics, volume 13, issue 3, 2013, Pages 369~380
DOI : 10.6113/JPE.2013.13.3.369
Direct torque control based on space vector modulation (SVM-DTC) protects the DTC transient merits. Furthermore, it creates better quality steady-state performance in a wide speed range. The modified method of DTC using SVM improves the electrical magnitudes of asynchronous machines, such as minimizing the stator current distortions, the stator flux with electromagnetic torque without ripple, the fast response of the rotor speed, and the constant switching frequency. In this paper, the proposed method is based on two new control strategies for direct torque control with space vector modulation. First, fuzzy logic control is used instead of the PI torque and a PI flux controller to minimizing the torque error and to achieve a constant switching frequency. The voltages in the direct and quadratic reference frame (
) are achieved by fuzzy logic control. In this scheme, the switching capability of the inverter is fully utilized, which improves the system performance. Second, the close loop of stator flux estimation based on the voltage model and a low pass filter is used to counteract the drawbacks in the open loop of the stator flux such as the problems saturation and dc drift. The response of this new control strategy is compared with DTC-SVM. The experimental and simulation results demonstrate that the proposed control topology outperforms the conventional DTC-SVM in terms of system robustness and eliminating the bad outcome of dc-offset.
A Sensorless PMDC Motor Speed Controller with a Logical Overcurrent Protection
Guerreiro, M.G. ; Foito, D. ; Cordeiro, A. ;
Journal of Power Electronics, volume 13, issue 3, 2013, Pages 381~389
DOI : 10.6113/JPE.2013.13.3.381
A method to control the speed or the torque of a permanent-magnet direct current motor is presented. The rotor speed and the external torque estimation are simultaneously provided by appropriate observers. The sensorless control scheme is based on current measurement and switching states of power devices. The observers performances are dependent on the accurate machine parameters knowledge. Sliding mode control approach was adopted for drive control, providing the suitable switching states to the chopper power devices. Despite the predictable chattering, a convenient first order switching function was considered enough to define the sliding surface and to correspond with the desired control specifications and drive performance. The experimental implementation was supported on a single dsPIC and the controller includes a logic overcurrent protection.
Controller Design of a Novel Power Conditioning System with an Energy Storage Device for Renewable Energy Sources under Grid-Connected Operation
Park, Sun-Jae ; Lee, Hwa-Seok ; Kim, Chan-In ; Park, Joung-Hu ; Jeon, Hee-Jong ; Ryeom, Jeongduk ;
Journal of Power Electronics, volume 13, issue 3, 2013, Pages 390~399
DOI : 10.6113/JPE.2013.13.3.390
As a result of the depletion of fossil fuels and environmental contamination, it has become important to use renewable energy. For the stable utilization of renewable energy sources, energy storage devices must be used. In addition, renewable and distributed power sources with energy storage devices must operate stably under grid-connected mode. This paper proposed dynamic response modeling for renewable power generation systems including a charger/discharger with an energy storage device in order to derive a method to guarantee stable operation while fully utilizing the energy from the energy storage device. In this paper, the principle operation and design guidelines of the proposed scheme are presented, along with a performance analysis and simulation results using MATLAB and PSIM. Finally, a hardware prototype of a 1kW power conditioning system with an energy storage device has been implemented for experimental verification of the proposed converter system.
A Discrete State-Space Control Scheme for Dynamic Voltage Restorers
Lei, He ; Lin, Xin-Chun ; Xue, Ming-Yu ; Kang, Yong ;
Journal of Power Electronics, volume 13, issue 3, 2013, Pages 400~408
DOI : 10.6113/JPE.2013.13.3.400
This paper presents a discrete state-space controller using state feedback control and feed-forward decoupling to provide a desirable control bandwidth and control stability for dynamic voltage restorers (DVR). The paper initially discusses three typical applications of a DVR. The load-side capacitor DVR topology is preferred because of its better filtering capability. The proposed DVR controller offers almost full controllability because of the multi-feedback of state variables, including one-beat delay feedback. Feed-forward decoupling is usually employed to prevent disturbances of the load current and source voltage. Directly obtaining the feed-forward paths of the load current and source voltage in the discrete domain is a complicated process. Fortunately, the full feed-forward decoupling strategy can be easily applied to the discrete state-space controller by means of continuous transformation. Simulation and experimental results from a digital signal processor-based system are included to support theoretical analysis.
Advanced Repetitive Controller to Improve the Voltage Characteristics of Distributed Generation with Nonlinear Loads
Trinh, Quoc-Nam ; Lee, Hong-Hee ;
Journal of Power Electronics, volume 13, issue 3, 2013, Pages 409~418
DOI : 10.6113/JPE.2013.13.3.409
This paper presents an enhanced control strategy which consists of a proportional-integral controller and a repetitive controller (RC) for improving the voltage performance of distributed generation (DG) under nonlinear load conditions. The proposed voltage controller is able to maintain a sinusoidal voltage at the point of common coupling (PCC) of the DG regardless of the harmonic voltage drop in the system impedance due to nonlinear load currents. In addition, by employing the delay time of the RC at one-sixth of the fundamental period, the proposed RC can overcome the slow response drawback of the traditional PI-RC. The proposed control strategy is analyzed and the design of the RC is presented in detail. The feasibility of the proposed control strategy is verified through simulation and experimental results.
Multivariable Optimal Control of a Direct AC/AC Converter under Rotating dq Frames
Wan, Yun ; Liu, Steven ; Jiang, Jianguo ;
Journal of Power Electronics, volume 13, issue 3, 2013, Pages 419~428
DOI : 10.6113/JPE.2013.13.3.419
The modular multilevel cascade converter (MMCC) is a new family of multilevel power converters with modular realization and a cascaded pattern for submodules. The MMCC family can be classified by basic configurations and submodule types. One member of this family, the Hexverter, is configured as Double-Delta Full-Bridge (DDFB). It is a novel multilevel AC/AC converter with direct power conversion and comparatively fewer required components. It is appropriate for connecting two three-phase systems with different frequencies and driving an AC motor directly from a utility grid. This paper presents the dq model of a Hexverter with both of its AC systems by state-space representation, which then simplifies the continuous time-varying model into a periodic discrete time-invariant one. Then a generalized multivariable optimal control strategy for regulating the Hexverter's independent currents is developed. The resulting control structure can be adapted to other MMCCs and is flexible enough to include other control criterion while guaranteeing the original controller performance. The modeling method and control design are verified by simulation results.
Modeling of Lithium Battery Cells for Plug-In Hybrid Vehicles
Shin, Dong-Hyun ; Jeong, Jin-Beom ; Kim, Tae-Hoon ; Kim, Hee-Jun ;
Journal of Power Electronics, volume 13, issue 3, 2013, Pages 429~436
DOI : 10.6113/JPE.2013.13.3.429
Online simulations are utilized to reduce time and cost in the development and performance optimization of plug-in hybrid electric vehicle (PHEV) and electric vehicles (EV) systems. One of the most important factors in an online simulation is the accuracy of the model. In particular, a model of a battery should accurately reflect the properties of an actual battery. However, precise dynamic modeling of high-capacity battery systems, which significantly affects the performance of a PHEV, is difficult because of its nonlinear electrochemical characteristics. In this study, a dynamic model of a high-capacity battery cell for a PHEV is developed through the extraction of the equivalent impedance parameters using electrochemical impedance spectroscopy (EIS). Based on the extracted parameters, a battery cell model is implemented using MATLAB/Simulink, and charging/discharging profiles are executed for comparative verification. Based on the obtained results, the model is optimized for a high-capacity battery cell for a PHEV. The simulation results show good agreement with the experimental results, thereby validating the developed model and verifying its accuracy.
Design of an LCL-Filter for Three-Parallel Operation of Power Converters in Wind Turbines
Jeong, Hae-Gwang ; Yoon, Dong-Keun ; Lee, Kyo-Beum ;
Journal of Power Electronics, volume 13, issue 3, 2013, Pages 437~446
DOI : 10.6113/JPE.2013.13.3.437
This paper proposes a design scheme for an LCL-filter used for the three-parallel operation of the power converters in high-capacity wind turbines. The designs of the power devices and grid connected filter are difficult due to the high level voltages and currents in huge-capacity wind turbines. To solve these problem, this paper presents three-parallel operation and LCL-filter design techniques optimized by parallel operation. Furthermore, the design of an inverter side inductance of the LCL-filter is discussed in detail considering the switching modulation method. Simulation and experimental results demonstrate the validity of the designed filter and wind turbines.
Systematic Current Control Strategy with Pole Assignment for Grid-Connected LCL-Filtered Inverters
Xu, Jinming ; Xie, Shaojun ; Tang, Ting ;
Journal of Power Electronics, volume 13, issue 3, 2013, Pages 447~457
DOI : 10.6113/JPE.2013.13.3.447
For grid-connected LCL-filtered inverters, resonance yields instability and low bandwidth. As a result, careful designs are required. This paper presents a systematic current control structure, where pole assignment consisting of one or more feedbacks is the inner loop, and the outer loop is the direct grid current control. Several other issues are discussed, such as the inner-loop feedback choices, pole-assignment algorithms, robustness and harmonic rejection. Generally, this kind of strategy has three different types according to the inner-loop feedback choices. Among them, a novel pole-assignment algorithm has been proposed, where the inner control maintains four freely-assigned poles which are just two pairs of conjugated poles located at the fundamental and resonance frequencies separately. It has been found that with the different types, the steady-state and dynamic performances are quite different. Finally, simulations and experiments have been provided to verify the control and design of the proposed methods.
Key Application Technologies of High Efficiency Power Quality Control Systems
Liu, Ding-Guo ; Shuai, Zhi-Kang ; Tu, Chun-Ming ; Cheng, Ying ; Luo, An ;
Journal of Power Electronics, volume 13, issue 3, 2013, Pages 458~468
DOI : 10.6113/JPE.2013.13.3.458
Large capacity reactive power compensation and harmonic control in the low-voltage grid of an enterprise, are important technical means to improve power quality and reduce power loss. In this paper, the principle of an efficient power quality controller is analyzed. Then, key application technologies of the HPQC which would influence the performances of the HPQC are studied. Based on an analysis of the harmonic shunt problem, a frequency dividing control strategy of the HPQC continuous subsystem is proposed. A parameter design method of the HPQC discrete subsystem and its installation method are also proposed to ensure the system compensation effect. HPQC systems have been designed for a copper foil plant. The effectiveness of this paper has been verified by the simulation and application results.
Control Strategy for Three-Phase Grid-Connected Converters under Unbalanced and Distorted Grid Voltages Using Composite Observers
Nguyen, Thanh Hai ; Lee, Dong-Choon ;
Journal of Power Electronics, volume 13, issue 3, 2013, Pages 469~478
DOI : 10.6113/JPE.2013.13.3.469
This paper proposes a novel scheme for the current controller for the grid-side converter (GSC) of permanent-magnet synchronous generator (PMSG) wind turbines to eliminate the high-order harmonics in the grid currents under grid voltage disturbances. The voltage unbalance and harmonics in three-phase systems cause grid current distortions. In order to mitigate the input current distortions, multi-loop current controllers are applied, where the positive-sequence component is regulated by proportional-integral (PI) controllers, and the negative-sequence and high-order harmonic components are regulated by proportional-resonance (PR) controllers. For extracting the positive/negative-sequence and harmonic components of the grid voltages and currents without a phase delay or magnitude reduction, composite observers are applied, which give faster and more precise estimation results. In addition, an active damping method using PR controllers to damp the grid current component of the resonant frequency is employed to improve the operating stability of VSCs with inductor-capacitor-inductor (LCL) filters. The validity of the proposed method is verified by simulation and experimental results.
Wireless Paralleled Control Strategy of Three-phase Inverter Modules for Islanding Distributed Generation Systems
Guo, Zhiqiang ; Sha, Deshang ; Liao, Xiaozhong ;
Journal of Power Electronics, volume 13, issue 3, 2013, Pages 479~486
DOI : 10.6113/JPE.2013.13.3.479
This paper presents a control strategy for distributed systems, which can be used in islanded microgrids. The control strategy is based on the droop method, which uses locally measured feedback to achieve load current sharing. Instead of the traditional droop method, an improved one is implemented. A virtual inductor in the synchronous frame for three-phase inverters is proposed to deal with the coupling of the frequency and the amplitude related to the active and reactive power. Compared with the traditional virtual inductor, the proposed virtual inductor is not affected by high frequency noises because it avoids differential calculations. A model is given for the distributed generation system, which is beneficial for the design of the droop coefficients and the value of the virtual inductor. The effectiveness of the proposed control strategy is verified by simulation and experiment results.
New Control Strategy for Three-Phase Grid-Connected LCL Inverters without a Phase-Locked Loop
Zhou, Lin ; Yang, Ming ; Liu, Qiang ; Guo, Ke ;
Journal of Power Electronics, volume 13, issue 3, 2013, Pages 487~496
DOI : 10.6113/JPE.2013.13.3.487
The three-phase synchronous reference frame phase-locked loop (SRF-PLL) is widely used for synchronization applications in power systems. In this paper, a new control strategy for three-phase grid-connected LCL inverters without a PLL is presented. According to the new strategy, a current reference can be generated by using the instantaneous power control scheme and the proposed positive-sequence voltage detector. Through theoretical analysis, it is indicated that a high-quality grid current can be produced by introducing the new control strategy. In addition, a kind of independent control for reactive power can be achieved under unbalanced and distorted grid conditions. Finally, the excellent performance of the proposed control strategy is validated by means of simulation and experimental results.
Improvement of Available Battery Capacity in Electric Vehicles
Liu, Yow-Chyi ;
Journal of Power Electronics, volume 13, issue 3, 2013, Pages 497~506
DOI : 10.6113/JPE.2013.13.3.497
This paper proposes a new method to improve the available battery capacity in electric vehicles by connecting lead-acid batteries with lithium-ion battery in parallel to supply power. In addition, this method combines the discharge characteristics of batteries to improve their efficiency and lower their cost for electric vehicles. A lithium-ion battery set is used to connect with N sets of lead-acid batteries in parallel. The lead-acid battery supplies the initial power. When the lead-acid battery is discharged by the load current until its output voltage drops to the cut-off voltage, the power management unit controls the lead-acid battery and changes it to discharge continuously with a small current. This discharge can be achieved by connecting the lead-acid battery to a lithium-ion battery in parallel to supply the load power or to discharge its current to another lead-acid or lithium-ion battery. Experimental results demonstrates that the available capacity can be improved by up to 30% of the rated capacity of the lead-acid batteries.