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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 12, Issue 6 - Nov 2012
Volume 12, Issue 5 - Sep 2012
Volume 12, Issue 4 - Jul 2012
Volume 12, Issue 3 - May 2012
Volume 12, Issue 2 - Mar 2012
Volume 12, Issue 1 - Jan 2012
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High Step-Down Multiple-Output LED Driver with the Current Auto-Balance Characteristic
Luo, Quanming ; Zhu, Binxin ; Lu, Weiguo ; Zhou, Luowei ;
Journal of Power Electronics, volume 12, issue 4, 2012, Pages 519~527
DOI : 10.6113/JPE.2012.12.4.519
A high step-down multiple-output LED driver is proposed in this paper. Firstly, the derivation of the driver with dual-output is presented and its operation principle and steady state performance are analyzed in detail. Secondly, a high step-down N-channel LED driver is proposed and its current auto-balance characteristic and step-down ratio are analyzed. Finally, an experimental prototype is built and the experimental results are given. The theoretical analysis and experimental results show that the proposed driver has the following virtues: First, if load balancing is achieved, the voltage gain is 1/N that of a Buck driver, where N is the number of channels. Second, each output automatically has an equal output current, without requiring more current close-loop control circuits than a Buck driver. Last, the voltage stresses of the switches and diodes are lower than those of a Buck driver, meaning that lower voltage switches and diodes can be used, and a higher efficiency can be expected.
Interleaved ZVS Resonant Converter with a Parallel-Series Connection
Lin, Bor-Ren ; Shen, Sin-Jhih ;
Journal of Power Electronics, volume 12, issue 4, 2012, Pages 528~537
DOI : 10.6113/JPE.2012.12.4.528
This paper presents an interleaved resonant converter with a parallel-series transformer connection in order to achieve ripple current reduction at the output capacitor, zero voltage turn-on for the active switches, zero current turn-off for the rectifier diodes, less voltage stress on the rectifier diodes, and less current stress on the transformer primary windings. The primary windings of the two transformers are connected in parallel in order to share the input current and to reduce the root-mean-square (rms) current on the primary windings. The secondary windings of the two transformers are connected in series in order to ensure that the transformer primary currents are balanced. A full-wave diode rectifier is used at the output side to clamp the voltage stress of the rectifier diode at the output voltage. Two circuit modules are operated with the interleaved PWM scheme so that the input and output ripple currents are reduced. Based on the resonant behavior, all of the active switches are turned on under zero voltage switching (ZVS), and the rectifier diodes are turned off under zero current switching (ZCS) if the operating switching frequency is less than the series resonant frequency. Finally, experiments with a 1kW prototype are described to verify the effectiveness of the proposed converter.
LMI-Based Robust Controllers for DC-DC Cascade Boost Converters
Torres-Pinzon, Carlos Andres ; Giral, Roberto ; Leyva, Ramon ;
Journal of Power Electronics, volume 12, issue 4, 2012, Pages 538~547
DOI : 10.6113/JPE.2012.12.4.538
This paper presents two different robust controllers for boost converters with two stages in a cascade. The first robust controller is monovariable; that is, the duty-cycle is the same for the two switches. The monovariable controller ensures that some prescribed constraints on pole placement and control effort are met, and optimizes the load disturbance rejection, while takes into account the uncertainty in certain parameters. The first controller is then compared with a multivariable robust controller; that is, with independent duty cycles in each switch. The multivariable controller takes into account the same uncertainty, constraints and optimization function. The comparison shows that the multivariable controller performs better at the expense of a slightly more complex implementation; that is, the multivariable controller provides a better rejection of the load disturbance. The paper also describes simulations and experimental results that are in perfect agreement with theoretical derivations.
Novel Single-State PWM Technique for Common-Mode Voltage Elimination in Multilevel Inverters
Nguyen, Nho-Van ; Quach, Hai-Thanh ; Lee, Hong-Hee ;
Journal of Power Electronics, volume 12, issue 4, 2012, Pages 548~558
DOI : 10.6113/JPE.2012.12.4.548
In this paper, a novel offset-based single-state pulse width modulation (PWM) method for achieving zero common-mode voltage (CMV) and reducing switching losses in multilevel inverters is presented. The specific active switching state of the zero common-mode (ZCM) voltage that approximates the reference voltage can be deduced from the switching state sequence of the reduced CMV phase disposition PWM (CMV PD PWM) method. From the reference leg voltages for the zero common-mode voltage, an N-to-2-level transformation defines a virtual two-level inverter and the corresponding nominal leg voltage references. The commutation process of the reduced CMV PD PWM method in a multilevel inverter and its outputs can be simply followed in a nominal switching time diagram for the virtual inverter. The characteristics of the reduced CMV PD PWM and the single-state PWM for zero common-mode voltage are analyzed in detail in this paper. The theoretical analysis of the proposed PWM method is verified by experimental results.
Design Method for the LCL Filters of Three-phase Voltage Source PWM Rectifiers
Guo, Xizheng ; You, Xiaojie ; Li, Xinran ; Hao, Ruixiang ; Wang, Dewei ;
Journal of Power Electronics, volume 12, issue 4, 2012, Pages 559~566
DOI : 10.6113/JPE.2012.12.4.559
A new design method for the LCL filters of three-phase voltage source PWM rectifiers is presented in this paper. Based on the single-phase harmonic equivalent model, the harmonic voltage of the rectifier side is calculated to design the LCL filter parameters by an iterative algorithm, in which the resonance frequency
and the ratio r between the grid-side inductance and the rectifier-side inductance are selected as known constants. The design criteria and process are introduced and the influence on the design result by the value of the resonance frequency
, ratio r is analyzed. Finally an example (600V, 500kW) is tested by simulation and experiment to verify the validity of the new design method.
A Novel DC Bus Voltage Balancing of Cascaded H-Bridge Converters in D-SSSC Application
Saradarzadeh, Mehdi ; Farhangi, Shahrokh ; Schanen, Jean-Luc ; Frey, David ; Jeannin, Pierre-Olivier ;
Journal of Power Electronics, volume 12, issue 4, 2012, Pages 567~577
DOI : 10.6113/JPE.2012.12.4.567
This paper introduces a new scheme to balance the DC bus voltages of a cascaded H-bridge converter which is used as a Distribution Static Synchronous Series Compensator (D-SSSC) in electrical distribution network. The aim of D-SSSC is to control the power flow between two feeders from different substations. As a result of different cell losses and capacitors tolerance the cells DC bus voltage can deviate from their reference values. In the proposed scheme, by individually modifying the reference PWM signal for each cell, an effective balancing procedure is derived. The new balancing procedure needs only the line current sign and is independent of the main control strategy, which controls the total DC bus voltages of cascaded H-bridge. The effect of modulation index variation on the capacitor voltage is analytically derived for the proposed strategy. The proposed method takes advantages of phase shift carrier based modulation and can be applied for a cascaded H-bridge with any number of cells. Also the system is immune to loss of one cell and the presented procedure can keep balancing between the remaining cells. Simulation studies and experimental results validate the effectiveness of the proposed method in the balancing of DC bus voltages.
Grid-Connected Photovoltaic System Based on a Cascaded H-Bridge Inverter
Rezaei, Mohammad-Ali ; Iman-Eini, Hossein ; Farhangi, Shahrokh ;
Journal of Power Electronics, volume 12, issue 4, 2012, Pages 578~586
DOI : 10.6113/JPE.2012.12.4.578
In this paper a single-phase Cascaded H-Bridge (CHB) inverter for photovoltaic (PV) applications is presented. Based on the presented mathematical analysis, a novel controller is introduced which adjusts the inverter power factor (PF) and manipulates the distribution of the reactive power between the cells to enhance the operating range of the CHB inverter. The adopted control strategy enables tracking of the maximum power point (MPP) of distinct PV strings and allows independent control of the dc-link voltages. The proposed controller also enables the inverter to operate under heavily unbalanced PV conditions. The performance of the CHB inverter and the proposed controllers are evaluated in the PSCAD/EMTDC environment. A seven-level CHB-based grid connected laboratory prototype is also utilized to verify the system performance.
Start-Up Current Control Method for Three-Phase PWM Rectifiers with a Low Initial DC-Link Voltage
Gu, Bon-Gwan ; Choi, Jun-Hyuk ; Jung, In-Soung ;
Journal of Power Electronics, volume 12, issue 4, 2012, Pages 587~594
DOI : 10.6113/JPE.2012.12.4.587
When a PWM rectifier has a low DC-link voltage during startup, the output voltage vector cannot be high enough to regulate the input current. This lack of a PWM rectifier output voltage vector can cause an unregulated inrush current when the rectifier operation starts. This paper presents a PWM rectifier start-up current control algorithm for when it starts operation with a lower DC-link voltage than unloaded condition case. To avoid the unregulated inrush current caused by a lack of DC-link voltage, the proposed control scheme regulates the one phase current with one switch chopping and it generates the current command considering the uncontrolled current magnitude information, which is calculated in advance. Simulation and experiment results support the validity of the proposed method.
Parallel Connected High Frequency AC Link Inverters Based on Full Digital Control
Sha, Deshang ; Guo, Zhiqiang ; Deng, Kai ; Liao, Xiaozhong ;
Journal of Power Electronics, volume 12, issue 4, 2012, Pages 595~603
DOI : 10.6113/JPE.2012.12.4.595
This paper presents a full digital control strategy for parallel connected modular inverter systems. Each modular inverter is a high frequency (HF) AC link inverter which is composed of a HF inverter and a HF transformer followed by a cycloconverter. To achieve equal sharing of the load current and to suppress the circulating currents among the modules, a three-loop control strategy, consisting of a common output voltage regulation (OVR) loop, individual circulating current suppression (CCS) loops and individual inner current tracking (ICT) loops, is proposed. The ICT loops are implemented with predictive current control from which high precision current tracking can be obtained. The effectiveness of the proposed control strategy is verified by simulation and experimental results from parallel connected two full-bridge HF AC link inverter modules.
Evaluation of Back-EMF Estimators for Sensorless Control of Permanent Magnet Synchronous Motors
Lee, Kwang-Woon ; Ha, Jung-Ik ;
Journal of Power Electronics, volume 12, issue 4, 2012, Pages 604~614
DOI : 10.6113/JPE.2012.12.4.604
This paper presents a comparative study of position sensorless control schemes based on back-electromotive force (back-EMF) estimation in permanent magnet synchronous motors (PMSM). The characteristics of the estimated back-EMF signals are analyzed using various mathematical models of a PMSM. The transfer functions of the estimators, based on the extended EMF model in the rotor reference frame, are derived to show their similarity. They are then used for the analysis of the effects of both the motor parameter variations and the voltage errors due to inverter nonlinearity on the accuracy of the back-EMF estimation. The differences between a phase-locked-loop (PLL) type estimator and a Luenberger observer type estimator, generally used for extracting rotor speed and position information from estimated back-EMF signals, are also examined. An experimental study with a 250-W interior-permanent-magnet machine has been performed to validate the analyses.
Control of Electrically Excited Synchronous Motors with a Low Switching Frequency
Yuan, Qing-Qing ; Wu, Xiao-Jie ; Dai, Peng ; Fu, Xiao ;
Journal of Power Electronics, volume 12, issue 4, 2012, Pages 615~622
DOI : 10.6113/JPE.2012.12.4.615
The switching frequency of the power electronic devices used in large synchronous motor drives is usually kept low (less than 1 kHz) to reduce the switching losses and to improve the converter power capability. However, this results in a couple of problems, e.g. an increase in the harmonic components of the stator current, and an undesired cross-coupling between the magnetization current component (
) and the torque component (
). In this paper, a novel complex matrix model of electrically excited synchronous motors (EESM) was established with a new control scheme for coping with the low switching frequency issues. First, a hybrid observer was proposed to identify the instantaneous fundamental component of the stator current, which results in an obvious reduction of both the total harmonic distortion (THD) and the low order harmonics. Then, a novel complex current controller was designed to realize the decoupling between
. Simulation and experimental results verify the effectiveness of this novel control system for EESM drives.
Digital Control Strategy for Single-phase Voltage-Doubler Boost Rectifiers
Cho, Young-Hoon ; Mok, Hyung-Soo ; Ji, Jun-Keun ; Lai, Jih-Sheng ;
Journal of Power Electronics, volume 12, issue 4, 2012, Pages 623~631
DOI : 10.6113/JPE.2012.12.4.623
In this paper, a digital controller design procedure is presented for single-phase voltage-doubler boost rectifiers (VDBR). The model derivation of the single-phase VDBR is performed in the s-domain. After that the simplified equivalent z-domain models are derived. These z-domain models are utilized to design the input current and the output dc-link voltage controllers. For the controller design in the z-domain, the traditional K-factor method is modified by considering the nature of the digital controller. The frequency pre-warping and anti-windup techniques are adapted for the controller design. By using the proposed method, the phase margin and the control bandwidth are accurately achieved as required by controller designers in a practical frequency range. The proposed method is applied to a 2.5 kVA single-phase VDBR for Uninterruptible Power Supply (UPS) applications. From the simulation and the experimental results, the effectiveness of the proposed design method has been verified.
Modeling and Filter Design through Analysis of Conducted EMI in Switching Power Converters
Vimala, R. ; Baskaran, K. ; Aravind Britto, K.R. ;
Journal of Power Electronics, volume 12, issue 4, 2012, Pages 632~642
DOI : 10.6113/JPE.2012.12.4.632
This paper presents a filter analysis of conducted Electro-Magnetic Interference (EMI) in switching power converters (SPC) based on noise impedances. The EMI characteristics of SPC can be analytically deduced from a circuit theoretical viewpoint. The analytical noise model is investigated to get a full understanding of the EMI mechanism. It is shown that with suitable and justified model, filters pertinent to EMI noise is investigated. The EMI noise is identified by time domain measurements associated with an isolated half-bridge ac-dc converter. Practical filters like LC filter,
filter and complete EMI filters are investigated. The proposed analysis and results can provide a guideline for improving the effectiveness of filtering schemes in SPC. Experimental results are also included to verify the validity of the proposed method. The results obtained satisfy the Federal Communications Commission (FCC) class A and class B regulations.
Analysis, Design and Implementation of an Interleaved DC/DC Converter with Series-Connected Transformers
Lin, Bor-Ren ; Chen, Chih-Chieh ;
Journal of Power Electronics, volume 12, issue 4, 2012, Pages 643~653
DOI : 10.6113/JPE.2012.12.4.643
An interleaved DC/DC converter with series-connected transformers is presented to implement the features of zero voltage switching (ZVS), load current sharing and ripple current reduction. The proposed converter includes two half-bridge converter cells connected in series to reduce the voltage stress of the switches at one-half of the input voltage. The output sides of the two converter cells with interleaved pulse-width modulation are connected in parallel to reduce the ripple current at the output capacitor and to achieve load current sharing. Therefore, the size of the output chokes and the capacitor can be reduced. The output capacitances of the MOSFETs and the resonant inductances are resonant at the transition instant to achieve ZVS turn-on. In addition, the switching losses on the power switches are reduced. Finally, experiments on a laboratory prototype (24V/40A) are provided to demonstrate the performance of the proposed converter.
Control Strategy Based on Equivalent Fundamental and Odd Harmonic Resonators for Single-Phase DVRs
Teng, Guofei ; Xiao, Guochun ; Hu, Leilei ; Lu, Yong ; Kafle, Yuba Raj ;
Journal of Power Electronics, volume 12, issue 4, 2012, Pages 654~663
DOI : 10.6113/JPE.2012.12.4.654
In this paper, a digital control strategy based on equivalent fundamental and odd harmonic resonators is proposed for single-phase DVRs. By using a delay block, which can be equivalent to a bank of resonators, it rejects the fundamental and odd harmonic disturbances effectively. The structure of the single closed-loop control system consists of a delay block, a proportional gain and a set of zero phase notch filters. The principle of the controller design is discussed in detail to ensure the stability of the system. Both the supply voltage and the load current feedforwards are used to improve the response speed and the ability to eliminate disturbances. The proposed controller is simple in terms of its structure and implementation. It has good performances in harmonic compensation and dynamic response. Experimental results from a 2kW DVR prototype confirm the validity of the design procedure and the effectiveness of the control strategy.
Phase Shift Control for Series Active Voltage Quality Regulators
Xiao, Guochun ; Teng, Guofei ; Chen, Beihai ; Zhang, Jixu ;
Journal of Power Electronics, volume 12, issue 4, 2012, Pages 664~676
DOI : 10.6113/JPE.2012.12.4.664
A phase shift algorithm based on the closed-loop control of dc-link voltage implemented on a series active voltage quality regulator (AVQR) is proposed in this paper. To avoid pumping-up the dc-link voltage, a general phase shift compensation strategy is applied. The relationships among the operation variables are discussed in detail, which is very important for guiding the design of both the main circuit and the control system. Then on the basis of an investigation of the dc-link voltage pumping-up from viewpoint of the active power flow, a novel phase shift control method based on the closed-loop of the dc-link voltage is proposed. This method can adjust the phase of the output voltage gradually and automatically according to the dc-link voltage variation without introducing a phase jump. The effectiveness of the proposed strategy is verified through simulations of a single-phase 5kVA prototype and laboratory experiments on both a single-phase 5kVA and a three-phase 15kVA prototype.
Power Current Control of a Resonant Vibratory Conveyor Having Electromagnetic Drive
Despotovic, Zeljko V. ; Ribic, Aleksandar I. ; Sinik, Vladimir M. ;
Journal of Power Electronics, volume 12, issue 4, 2012, Pages 677~688
DOI : 10.6113/JPE.2012.12.4.677
The vibratory conveyors with electromagnetic drive are used for performing gravimetric flow of granular materials in processing industry. By realizing free vibrations of variable intensity and frequency over a wide range through application of the electromagnetic actuator, suitable power converter, and the corresponding controller, continuous conveyance of granular materials have been provided for various operating conditions. Standard power output stages intended for control of vibratory conveyance using thyristors and triacs. Phase angle control can only accomplish tuning of amplitude oscillations, but oscillation frequency cannot be adjusted by these converters. Application of current controlled transistor converters enables accomplishing the amplitude and/or frequency control. Their use implies the excitation of a vibratory conveyor independent of the supply network frequency. In addition, the frequency control ensures operation in the region of mechanical resonance. Operation in this region is favourable from the energy point of view, since it requires minimal energy consumption. The paper presents a possible solution and advantages of the amplitude-frequency control of vibratory conveyors by means of a current controlled power converter.