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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 11, Issue 6 - Nov 2011
Volume 11, Issue 5 - Sep 2011
Volume 11, Issue 4 - Jul 2011
Volume 11, Issue 3 - May 2011
Volume 11, Issue 2 - Mar 2011
Volume 11, Issue 1 - Jan 2011
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Novel Interleaved Single-Stage AC/DC Converter with a High Power Factor and High Efficiency
Wang, Yijie ; Wang, Wei ; Zhang, Xiangjun ; Xu, Dianguo ;
Journal of Power Electronics, volume 11, issue 3, 2011, Pages 245~255
DOI : 10.6113/JPE.2011.11.3.245
A novel single-stage AC/DC converter with the soft-switching characteristic based on interleaving technology and an LLC topology is proposed here. The converter is integrated by an interleaved cell and an LLC cell. Because the components of the system are reduced as a result of integrating, the cost decreases. Since interleaving technology is adopted, the converter can work in a high voltage input state. The LLC topology chosen here ensures that the switches on the primary side work in the ZVS condition and that the diodes on the secondary side work in the ZCS condition, which decreases the switching loss of the system. A theoretical analysis and the design procedures of the proposed converter are proposed and discussed in detail. Simulations and experimental studies with a 100W prototype are done to prove the analysis.
Primary Current Generation for a Contactless Power Transfer System Using Free Oscillation and Energy Injection Control
Li, Hao Leo ; Hu, Aiguo Patrick ; Covic, Grant Anthony ;
Journal of Power Electronics, volume 11, issue 3, 2011, Pages 256~263
DOI : 10.6113/JPE.2011.11.3.256
This paper utilizes free oscillation and energy injection principles to generate and control the high frequency current in the primary track of a contactless power transfer system. Here the primary power inverter maintains natural resonance while ensuring near constant current magnitude in the primary track as required for multiple independent loads. Such energy injection controllers exhibit low switching frequency and achieve ZCS (Zero Current Switching) by detecting the high frequency current, thus the switching stress, power losses and EMI of the inverter are low. An example full bridge topology is investigated for a contactless power transfer system with multiple pickups. Theoretical analysis, simulation and experimental results show that the proposed system has a fast and smooth start-up transient response. The output track current is fully controllable with a sufficiently good waveform for contactless power transfer applications.
Novel Passive Snubber Suitable for Three-Phase Single-Stage PFC Based on an Isolated Full-Bridge Boost Topology
Meng, Tao ; Ben, Hongqi ; Wang, Daqing ; Song, Jianfeng ;
Journal of Power Electronics, volume 11, issue 3, 2011, Pages 264~270
DOI : 10.6113/JPE.2011.11.3.264
In this paper a novel passive snubber is proposed, which can suppress the voltage spike across the bridge leg of the isolated full-bridge boost topology. The snubber is composed of capacitors, inductors and diodes. Two capacitors connected in series are used to absorb the voltage spike and the energy of each capacitor can be transferred to the load during one switching cycle by the resonance of the inductors and capacitors. The operational principle of the passive snubber is analyzed in detail based on a three-phase power factor correction (PFC) converter, and the design considerations of both the converter and the snubber are given. Finally, a 3kW laboratory-made prototype is built. The experimental results verify the theoretical analysis and evaluations. They also prove the validity and feasibility of the proposed methods.
A High Efficiency Controller IC for LLC Resonant Converter in 0.35 μm BCD
Hong, Seong-Wha ; Kim, Hong-Jin ; Park, Hyung-Gu ; Park, Joon-Sung ; Pu, Young-Gun ; Lee, Kang-Yoon ;
Journal of Power Electronics, volume 11, issue 3, 2011, Pages 271~278
DOI : 10.6113/JPE.2011.11.3.271
This paper presents a LLC resonant controller IC for secondary side control without external active devices to achieve low profile and low cost LED back light units. A gate driving transformer is adopted to isolate the primary side and the secondary side instead of an opto-coupler. A new integrated dimming circuitry is proposed to improve the dynamic current control characteristic and the current density of a LED for the brightness modulation of a large screen LCD. A dual-slope clock generator is proposed to overcome the frequency error due to the under shoot in conventional approaches. This chip is fabricated using 0.35
BCD technology and the die size is
. The frequency range of the clock generator is from 50 kHz to 500 kHz and the range of the dead time is from 50 ns to 2.2
. The efficiency of the LED driving circuit is 97 % and the current consumption is 40 mA for a 100 kHz operation frequency from a 15 V supply voltage.
Algorithm for Reducing the Effect of Network Delay of Sensor Data in Network-Based AC Motor Drives
Chun, Tae-Won ; Ahn, Jung-Ryol ; Lee, Hong-Hee ; Kim, Heung-Geun ; Nho, Eui-Cheol ;
Journal of Power Electronics, volume 11, issue 3, 2011, Pages 279~284
DOI : 10.6113/JPE.2011.11.3.279
Network-based controls for ac motor drive systems are becoming increasingly important. In this paper, an ac motor control system is implemented by a motor control module and three sensor modules such as a voltage sensor module, a current sensor module, and an encoder module. There will inevitably be network time delays from the sensor modules to the motor control system, which often degrades and even destabilizes the motor drive system. As a result, it becomes very difficult to estimate the network delayed ac sensor data. An algorithm to reduce the effects of network time delays on sensor data is proposed, using both a synchronization signal and a simple method for estimating the sensor data. The algorithm is applied to a vector controlled induction motor drive system, and the performance of the proposed algorithm is verified with experiments.
Novel SRM Drive Systems Using Variable DC-Link Voltage
Jang, Do-Hyun ;
Journal of Power Electronics, volume 11, issue 3, 2011, Pages 285~293
DOI : 10.6113/JPE.2011.11.3.285
This paper proposes two SRM driving systems using a variable dc-link voltage controlled by a single-phase inverter. Two SRM converter topologies of a half bridge type and a full bridge type are proposed according to the power circuits of an inverter. The phase current can be controlled by means of a PWM controller at the inverter, and the turn-on/off angle at the phase switches can be controlled by a position sensor at the converter in the drive system. The inverter acts as a peak-current limiter if the transient current exceeds its maximum value. SRMs using the proposed topologies maintain high efficiency due to energy regeneration after the turn-off of power switches. The operational modes of the proposed topologies are verified by simulation and experimental results.
A Five-Phase Induction Motor Speed Control System Excluding Effects of 3rd Current Harmonics Component
Kim, Min-Huei ; Kim, Nam-Hun ; Baik, Won-Sik ;
Journal of Power Electronics, volume 11, issue 3, 2011, Pages 294~303
DOI : 10.6113/JPE.2011.11.3.294
In this paper an effective five-phase induction motor (IM) and its drive methods are proposed. Due to the additional degrees of freedom, the five-phase IM drive presents unique characteristics for enhancing the torque producing capability of the motor. Also the five-phase motor drives possess many other advantages when compared to traditional three-phase motor drives. Some of these advantages include, reducing the amplitude and increasing the frequency of the torque pulsation, reducing the amplitude of the current without increasing the voltage per phase and increasing the reliability. In order to maximize the torque per ampere, the proposed motor has concentrated winding, the produced back electromotive force (EMF) is almost trapezoidal, and the motor is supplied with the combined sinusoidal plus the third harmonic of the currents. For demonstrating the superior performance of the proposed five-phase IM, the motors are also analyzed on the synchronously rotating reference frame. To supply trapezoidal current waveform and to exclude the effect of the
harmonic current, a new control stratagem is proposed. The proposed control method is based on direct torque control (DTC) and rotor flux oriented control (RFOC) of the five-phase IM drives. It is able to reduce the acoustical noise, the torque, the flux, the current, and the speed pulsations during the steady state. The DTC transient merits are preserved, while a better quality steady-state performance is produced in the five phase motor drive for a wide speed range. Experimental results clearly demonstrated a more dynamic steady state performance with the proposed control system.
Design of a Discrete Flux Observer by the Power Series Approximation
Kim, Kyung-Seo ; Kim, Il-Han ;
Journal of Power Electronics, volume 11, issue 3, 2011, Pages 304~310
DOI : 10.6113/JPE.2011.11.3.304
The power series approximation method is proposed for real time implementations of a discrete flux observer. The proposed method improves the performance of the discrete flux observer in the case of a low sampling rate and high speed range, where the simple discrete flux observer converted by the Euler method cannot estimate the actual flux precisely. The performance of discrete flux observers with different orders of approximation is compared to find out the proper order of approximation. The validity of the proposed method is verified through simulation and experiment.
Active Damping Method Using Grid-Side Current Feedback for Active Power Filters with LCL Filters
Tang, Shiying ; Peng, Li ; Kang, Yong ;
Journal of Power Electronics, volume 11, issue 3, 2011, Pages 311~318
DOI : 10.6113/JPE.2011.11.3.311
LCL filters installed at converter outputs offer a higher harmonic attenuation than L filters. However, as a three order resonant circuit, it is difficult to stabilize and has a risk of oscillating with the power grid. Therefore, careful design is required to damp LCL resonance. Compared to a passive damping method, an active damping method is a more attractive solution for this problem, since it avoids extra power losses. In this paper, the damping capabilities of capacitor current, capacitor voltage, and grid-side current feedback methods, are analyzed under the discrete-time state-space model. Theoretical analysis shows that the grid-side current feedback method is more suitable for use in active power filters, because it can damp LCL resonance more effectively than the other two methods when the ratio of the resonance and the control frequency is between 0.225 and 0.325. Furthermore, since there is no need for extra sensors for additional states measurements, this method provides a cost-efficient solution. To support the theoretical analysis, the proposed method is tested on a 7-kVA single-phase shunt active power filter.
Modeling of Belt-Pulley and Flexible Coupling Effects on Submarine Driven System Electrical Motors
Jafarboland, Mehrdad ; Zadehbagheri, Mahmoud ;
Journal of Power Electronics, volume 11, issue 3, 2011, Pages 319~326
DOI : 10.6113/JPE.2011.11.3.319
Nowadays numerous research projects are being conducted in the field of electric motors. Non-modeling of flexible connections such as couplings and the belt-pulley do not show some real behaviors. With an increase in the number of connections and drive factors, these Non-modeled modes become more important. The coupling of two electric motors, instead of one motor, in submarine propeller force is an obvious example which shows that Non-modeled vibration modes caused by flexible connections can disturb controller operation and make undesirable vibrations in the submarine body. In this paper a dynamic model of flexible connections and a completed dynamic model of two different coupled electric models is presented. A robust controller for the completed model is also amended so that the two controlling targets of a desired speed adjustment and an appropriate load division between the two motors with sufficient accuracy are achieved.
Piecewise Affine Control Design for Power Factor Correction Rectifiers
Tahami, Farzad ; Poshtkouhi, Shahab ; Ahmadian, Hamed Molla ;
Journal of Power Electronics, volume 11, issue 3, 2011, Pages 327~334
DOI : 10.6113/JPE.2011.11.3.327
Single-phase power factor correction (PFC) converter circuits are non-linear systems due to the contribution of their multiplier. This non-linearity causes difficulties in analysis and design. Models that reduce the system to a linear system involve considerable approximation, and produce results that are susceptible to instability problems. In this paper a piecewise affine (PWA) system is introduced for describing the nonlinear averaged model. Then robust output feedback controllers are established in terms of the linear matrix inequality (LMI). Simulation and experiments results show the effectiveness of the proposed control method.
Improved Orientation Strategy for Energy-Efficiency in Photovoltaic Panels
Dousoky, Gamal M. ; El-Sayed, Abou-Hashema M. ; Shoyama, Masahito ;
Journal of Power Electronics, volume 11, issue 3, 2011, Pages 335~341
DOI : 10.6113/JPE.2011.11.3.335
This paper presents an improved orientation strategy for energy-efficiency in photovoltaic (PV) panels. Conventionally, PV panels are tilted with the site`s latitude angle or the difference between the latitude angle and the solar declination angle. A monthly-based orientation strategy has been proposed and analyzed in this study. The proposed strategy implies that the PV panels are tilted with the monthly-based angle that achieves the maximum incident radiation. Furthermore, the impact of using the proposed orientation strategy and three conventional strategies on the produced power and on the PV system design features has been investigated in detail. A Japanese city (Fukuoka) and an Egyptian city (Al-Kharijah) have been considered as locations for the PV power system installation. The results showed that the proposed strategy achieved an increase in the power produced from the PV power systems at the two different sites, and consequently the required solar cells area can be saved. Therefore, the cost of the PV power system components can be reduced including the solar cells area and the land area.
Sliding Mode Controller for Torque and Pitch Control of PMSG Wind Power Systems
Lee, Sung-Hun ; Joo, Young-Jun ; Back, Ju-Hoon ; Seo, Jin-Heon ; Choy, Ick ;
Journal of Power Electronics, volume 11, issue 3, 2011, Pages 342~349
DOI : 10.6113/JPE.2011.11.3.342
We propose a torque and pitch control scheme for variable speed wind turbines with permanent magnet synchronous generator (PMSG). A torque controller is designed to maximize the power below the rated wind speed and a pitch controller is designed to regulate the output power above the rated wind speed. The controllers exploit the sliding mode control scheme considering the variation of wind speed. Since the aerodynamic torque and rotor acceleration are difficult to measure in practice, a finite time convergent observer is designed which estimates them. In order to verify the proposed control strategy, we present stability analysis as well as simulation results.
DC Micro-Grid Operational Analysis with a Detailed Simulation Model for Distributed Generation
Lee, Ji-Heon ; Kim, Hyun-Jun ; Han, Byung-Moon ; Jeong, Yu-Seok ; Yang, Hyo-Sik ; Cha, Han-Ju ;
Journal of Power Electronics, volume 11, issue 3, 2011, Pages 350~359
DOI : 10.6113/JPE.2011.11.3.350
This paper describes the operational analysis results of a DC micro-grid using a detailed model of distributed generation. A detailed model of wind power generation, photo-voltaic generation and fuel cell generation was implemented with an userdefined model created with PSCAD/EMTDC software and coded in C-language. The operational analysis was carried out using PSCAD/EMTDC software, in which the power circuit is implemented by a built-in model and the controller is modeled by an user-defined model that is also coded in C-language. Various simulation results confirm that a DC micro-grid can operate without any problems in both the grid-tied mode and in the islanded mode. The operational analysis results confirm that the DC micro-grid makes it feasible to provide power to the load stably. It can also be utilized to develop an actual system design.
Active Frequency with a Positive Feedback Anti-Islanding Method Based on a Robust PLL Algorithm for Grid-Connected PV PCS
Lee, Jong-Pil ; Min, Byung-Duk ; Kim, Tae-Jin ; Yoo, Dong-Wook ; Yoo, Ji-Yoon ;
Journal of Power Electronics, volume 11, issue 3, 2011, Pages 360~368
DOI : 10.6113/JPE.2011.11.3.360
This paper proposes an active frequency with a positive feedback in the d-q frame anti-islanding method suitable for a robust phase-locked loop (PLL) algorithm using the FFT concept. In general, PLL algorithms for grid-connected PV PCS use d-q transformation and controllers to make zero an imaginary part of the transformed voltage vector. In a real grid system, the grid voltage is not ideal. It may be unbalanced, noisy and have many harmonics. For these reasons, the d-q transformed components do not have a pure DC component. The controller tuning of a PLL algorithm is difficult. The proposed PLL algorithm using the FFT concept can use the strong noise cancelation characteristics of a FFT algorithm without a PI controller. Therefore, the proposed PLL algorithm has no gain-tuning of a PI controller, and it is hardly influenced by voltage drops, phase step changes and harmonics. Islanding prediction is a necessary feature of inverter-based photovoltaic (PV) systems in order to meet the stringent standard requirements for interconnection with an electrical grid. Both passive and active anti-islanding methods exist. Typically, active methods modify a given parameter, which also affects the shape and quality of the grid injected current. In this paper, the active anti-islanding algorithm for a grid-connected PV PCS uses positive feedback control in the d-q frame. The proposed PLL and anti-islanding algorithm are implemented for a 250kW PV PCS. This system has four DC/DC converters each with a 25kW power rating. This is only one-third of the total system power. The experimental results show that the proposed PLL, anti-islanding method and topology demonstrate good performance in a 250kW PV PCS.
Enhanced Dynamic Response of SRF-PLL System for High Dynamic Performance during Voltage Disturbance
Choi, Hyeong-Jin ; Song, Seung-Ho ; Jeong, Seung-Gi ; Choi, Ju-Yeop ; Choy, Ick ;
Journal of Power Electronics, volume 11, issue 3, 2011, Pages 369~374
DOI : 10.6113/JPE.2011.11.3.369
Usually, a LPF (low pass filter) is used in the feedback loop of a SRF (synchronous reference frame) - PLL (phase locked loop) system because the measured grid voltage contains harmonic distortions and sensor noises. In this paper, it is shown that the cut-off frequency of the LPF should be designed to suppress the harmonic ripples contained in the measured voltage. Also, a new design method for the loop gain of the PI-type controller in the SRF-PLL is proposed with consideration of the dynamics of the LPF. As a result, a better transient response can be obtained with the proposed design method. The LPF frequency and the PI controller gain are designed in coordination according to the steady state and dynamic performance requirements. Furthermore, in the proposed method, the controller gain and the LPF cut-off frequency are changed from their normal value to a transient value when a voltage disturbance is detected. This paper shows the feasibility and usefulness of the proposed methods through the computer simulations and experimental results.
Design of Robust Current Controller Using GA for Three Level 24-Pulse VSC Based STATCOM
Janaki, M. ; Thirumalaivasan, R. ; Prabhu, Nagesh ;
Journal of Power Electronics, volume 11, issue 3, 2011, Pages 375~380
DOI : 10.6113/JPE.2011.11.3.375
A STATic synchronous COMpensator (STATCOM) is a shunt connected voltage source converter (VSC) based FACTS controller using Gate Turn Off (GTO) power semiconductor devices employed for reactive power control. The operation principal is similar to that of a synchronous condenser. A typical application of a STATCOM is voltage regulation at the midpoint of a long transmission line for the enhancement of power transfer capability and/or reactive power control at the load centre. This paper presents the modeling of STATCOM with twenty four pulse three level VSC and Type-1 controller to regulate the reactive current or the bus voltage. The performance is evaluated by transient simulation. It is observed that, the STATCOM shows excellent transient response to step change in the reactive current reference. While the eigenvalue analysis is based on D-Q model, the transient simulation is based on both D-Q and 3 phase models of STATCOM (which considers switching action of VSC).
Physical Modeling of SiC Power Diodes with Empirical Approximation
Hernandez, Leobardo ; Claudio, Abraham ; Rodriguez, Marco A. ; Ponce, Mario ; Tapia, Alejandro ;
Journal of Power Electronics, volume 11, issue 3, 2011, Pages 381~388
DOI : 10.6113/JPE.2011.11.3.381
This article presents the development of a model for SiC power diodes based on the physics of the semiconductor. The model is able to simulate the behavior of the dynamics of the charges in the N- region based on the stored charge inside the SiC power diode, depending on the working regime of the device (turn-on, on-state, and turn-off). The optimal individual calculation of the ambipolar diffusion length for every phase of commutation allows for solving the ambipolar diffusion equation (ADE) using a very simple approach. By means of this methodology development a set of differential equations that models the main physical phenomena associated with the semiconductor power device are obtained. The model is developed in Pspice with acceptable simulation times and without convergence problems during its implementation.