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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Power Electronics
Journal Basic Information
Journal DOI :
The Korean Institute of Power Electronics
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Volume & Issues
Volume 8, Issue 4 - Oct 2008
Volume 8, Issue 3 - Jul 2008
Volume 8, Issue 2 - Apr 2008
Volume 8, Issue 1 - Feb 2008
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Power System and Drive-Train for Omni-Directional Autonomous Mobile Robots with Multiple Energy Storage Units
Ghaderi, Ahmad ; Nassiraei, Amir A.F ; Sanada, Atsushi ; Ishii, Kazuo ; Godler, Ivan ;
Journal of Power Electronics, volume 8, issue 4, 2008, Pages 291~300
In this paper power system and drive-train for omni-directional autonomous mobile robots with multiple energy storage units are presented. Because in proposed system, which is implemented in soccer robots, the ability of power flow control from of multiple separated energy storage units and speed control for each motor are combined, these robots can be derived by more than one power source. This capability, allow robot to diversify its energy source by employing hybrid power sources. In this research Lithium ion polymer batteries have been used for main and auxiliary energy storage units because of their high power and energy densities. And to protect them against deep discharge, over current and short circuit, a protection circuit was designed. The other parts of our robot power system are DC-DC converters and kicker circuit. The simulation and experimental results show proposed scheme and extracted equations are valid and energy management and speed control can be achieved properly using this method. The filed experiments show robot mobility functions to perform the requested motion is enough and it has a high maneuverability in the field.
Hybrid Sensor-less Control of Permanent Magnet Synchronous Motor in Low-speed Region
Yamamoto, Yasuhiro ; Funato, Hirohito ; Ogasawara, Satoshi ;
Journal of Power Electronics, volume 8, issue 4, 2008, Pages 301~308
This paper proposes a method of improving the stability in sensor-less control of permanent magnet synchronous motors. The control method for low-speed region is divided into two: One is a high frequency method, which involves a problem of reverse rotation once misdetection of the permanent magnet polarity should occur, and another one is a current drive method, which has a problem that phase and speed oscillations are caused by quick speed changes. Hence, authors propose adoption of the current drive method for the basic control system with added compensation of stabilization by means of the high frequency method. This combination secures stable control with no risk of reversal and less vibration. In addition, authors have also considered a frequency separation filter of a shorter delay time so that current control performance will not lower even when high frequencies are introduced. This filter has achieved simplified compensation using repetitive characteristic through the utilization of the periodicity of high frequency current. Simulation and experiment have been conducted to verify that the stable performance of this system is improved.
A Novel Grid-Connected PV PCS with New High Efficiency Converter
Min, Byung-Duk ; Lee, Jong-Pil ; Kim, Jong-Hyun ; Kim, Tae-Jin ; Yoo, Dong-Wook ; Ryu, Kang-Ryoul ; Kim, Jeong-Joong ; Song, Eui-Ho ;
Journal of Power Electronics, volume 8, issue 4, 2008, Pages 309~316
In this paper, new topology is proposed that can dramatically reduce the converter power rating and increase the efficiency of total PV system. Since the output voltage of PV module has very wide voltage range, in general, the DC/DC converter is used to get constant high DC voltage. According to analysis of PV characteristics, in proposed topology, only 20% power of total PV system power is needed for DC/DC converter. DC/DC converter used in proposed topology has flat efficiency curve at all load range and very high efficiency characteristics. The total system efficiency is the product of that of converter and that of inverter. In proposed topology, because the converter efficiency curve is flat all load range, the total system efficiency at the low power range is dramatically improved. The proposed topology is implemented for 200kW PCS system. This system has only three DC/DC converters with 20kW power rating each other. It is only one-third of total system power. The experiment results show that the proposed topology has good performance.
A Multiband Shunt Hybrid Active Filter with Sensorless Control
Kumar S, Surendra ; Sensarma, Partha Sarathi ;
Journal of Power Electronics, volume 8, issue 4, 2008, Pages 317~324
This paper proposes a Multiband Shunt Hybrid Active Filter (SHAF) with sensorless control. A plant is modeled in the discrete- time domain and a controller is designed using the Pole shifting law in the polynomial domain. This control approach is very useful for filtering the load harmonics with reduced sensor counts where a low cost solution like SHAF is required. Multiple Synchronous Reference Frames (MSRF) and low pass filters are used to measure the
harmonic components separately from the load and filter currents. Individual current controllers are designed for the
harmonic currents. Control is realized in the stationary, three-phase (abc) reference frame. Performance of the controller is validated through simulation, using realistic plant and controller models, as well as experimentally on a full-scale distribution system.
Monitoring for Mutual Effects of Switching Power Capacitors in Power Systems
Ghania, Samy M. ; Elwer, Ayman S. ; Morsi, Reda ; Salama, M.M.A. ;
Journal of Power Electronics, volume 8, issue 4, 2008, Pages 325~331
Power system perturbations are due to many reasons; one of the most common perturbation causes is switching off/on the power capacitors. This paper monitors and discusses the overvoltages which appear on local and remote capacitor connected buses in power systems. Using the Fast Fourier Transfer (FFT), the total harmonic content of voltages and currents waveforms is also estimated at all buses. The power factor during different cases of switching modes "off/on" is monitored. The monitoring technique tackles not only the longitudinal long distance mutual effects of switching power capacitors between different buses but also evaluates the overvoltage durations. A relative long term monitoring is implemented using the Matlab/Simulink environment to show severity assessments in different switching modes on the transformers' voltages and currents' waveforms.
Phase Angle Control in Resonant Inverters with Pulse Phase Modulation
Ye, Zhongming ; Jain, Praveen ; Sen, Paresh ;
Journal of Power Electronics, volume 8, issue 4, 2008, Pages 332~344
High frequency AC (HFAC) power distribution systems delivering power through a high frequency AC link with sinusoidal voltage have the advantages of simple structure and high efficiency. In a multiple module system, where multiple resonant inverters are paralleled to the high frequency AC bus through connection inductors, it is necessary for the output voltage phase angles of the inverters be controlled so that the circulating current among the inverters be minimized. However, the phase angle of the resonant inverters output voltage can not be controlled with conventional phase shift modulation or pulse width modulation. The phase angle is a function of both the phase of the gating signals and the impedance of the resonant tank. In this paper, we proposed a pulse phase modulation (PPM) concept for the resonant inverters, so that the phase angle of the output voltage can be regulated. The PPM can be used to minimize the circulating current between the resonant inverters. The mechanisms of the phase angle control and the PPM were explained. The small signal model of a PPM controlled half-bridge resonant inverter was analyzed. The concept was verified in a half bridge resonant inverter with a series-parallel resonant tank. An HFAC power distribution system with two resonant inverters connected in parallel to a 500kHz, 28V AC bus was presented to demonstrate the applicability of the concept in a high frequency power distribution system.
Optimal Efficiency Control of Induction Generators in Wind Energy Conversion Systems using Support Vector Regression
Lee, Dong-Choon ; Abo-Khalil, Ahmed. G. ;
Journal of Power Electronics, volume 8, issue 4, 2008, Pages 345~353
In this paper, a novel loss minimization of an induction generator in wind energy generation systems is presented. The proposed algorithm is based on the flux level reduction, for which the generator d-axis current reference is estimated using support vector regression (SVR). Wind speed is employed as an input of the SVR and the samples of the generator d-axis current reference are used as output to train the SVR algorithm off-line. Data samples for wind speed and d-axis current are collected for the training process, which plots a relation of input and output. The predicted off-line function and the instantaneous wind speed are then used to determine the d-axis current reference. It is shown that the effect of loss minimization is more significant at low wind speed and the loss reduction is about to 40% at 4[m/s] wind speed. The validity of the proposed scheme has been verified by experimental results.
Precision Position Control of PMSM using Neural Observer and Parameter Compensator
Ko, Jong-Sun ; Seo, Young-Ger ; Kim, Hyun-Sik ;
Journal of Power Electronics, volume 8, issue 4, 2008, Pages 354~362
This paper presents neural load torque compensation method which is composed of a deadbeat load torque observer and gains compensation by a parameter estimator. As a result, the response of the PMSM (permanent magnet synchronous motor) obtains better precision position control. To reduce the noise effect, the post-filter is implemented by a MA (moving average) process. The parameter compensator with an RLSM (recursive least square method) parameter estimator is adopted to increase the performance of the load torque observer and main controller. The parameter estimator is combined with a high performance neural load torque observer to resolve problems. The neural network is trained in online phases and it is composed by a feed forward recall and error back-propagation training. During normal operation, the input-output response is sampled and the weighting value is trained multi-times by the error back-propagation method at each sample period to accommodate the possible variations in the parameters or load torque. As a result, the proposed control system has a robust and precise system against load torque and parameter variation. Stability and usefulness are verified by computer simulation and experiment.
Comparison of PWM Strategies for Three-Phase Current-fed DC/DC Converters
Cha, Han-Ju ; Choi, Soon-Ho ; Han, Byung-Moon ;
Journal of Power Electronics, volume 8, issue 4, 2008, Pages 363~370
In this paper, three kinds of PWM strategies for a three-phase current-fed dc/dc converter are proposed and compared in terms of losses and voltage transfer ratio. Each PWM strategy is described graphically and their switching losses are analyzed. With the proposed PWM C strategy, one turn-off switching of each bridge switch is eliminated to reduce switching losses under the same switching frequency. In addition, RMS current through the bridge switches is lowered by using parallel connection between two bridge switches and thus, conduction losses of the switches are reduced. Further, copper losses of the transformer are decreased due to the reduced RMS current of each transformer's winding. Therefore, total losses are minimized and the efficiency of the converter is improved by using the proposed PWM C strategy. Digital signal processor (DSP: TI320LF2407) and a field-programmable gate array (FPGA: EPM7128) board are used to generate PWM patterns for three-phase bridge and clamp MOSFETs. A 500W prototype converter is built and its experimental results verify the validity of the proposed PWM strategies.
Utility Interactive PV Systems with Power Shaping Function for Increasing Peak Power Cut Effect
Choe, Gyu-Ha ; Kim, Hong-Sung ; Heo, Hye-Seong ; Jeong, Byong-Hwan ; Choi, Young-Ho ; Kim, Jae-Chul ;
Journal of Power Electronics, volume 8, issue 4, 2008, Pages 371~380
This paper describes the Utility Interactive PV (UIPV) system which can improve the peak-cut effect by adding an energy storage device of batteries to the power converter. The proposed system has three possible operation modes depending on relative condition of PV output, which can have the power shaping function covering the peak power for 3 hours. A new power circuit and an application algorithm have been applied to the UIPV system which is based on working PV system during a 3-hour peak time. The energy relationship by the proposed system is analyzed theoretically and experimentally. The proposed system is evaluated at the viewpoint of cost and total spacing, which enables the proposed UIPV system to have the reduction of the peak power demand and hence to improve the power capacity of peak cut.