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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 16, Issue 5 - Sep 2016
Volume 16, Issue 4 - Jul 2016
Volume 16, Issue 3 - May 2016
Volume 16, Issue 2 - Mar 2016
Volume 16, Issue 1 - Jan 2016
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A High-efficiency Method to Suppress Transformer Core Imbalance in Digitally Controlled Phase-shifted Full-bridge Converter
Yu, Juzheng ; Qian, Qinsong ; Sun, Weifeng ; Zhang, Taizhi ; Lu, Shengli ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 823~831
DOI : 10.6113/JPE.2016.16.3.823
A high-efficiency method is proposed to suppress magnetic core imbalance in phase-shifted full-bridge (PSFB) converters. Compared with conventional solutions, such as controlling peak current mode (PCM) or adding DC blocking capacitance, the proposed method has several advantages, such as lower power loss and smaller size, because the additional current sensor or blocking capacitor is removed. A time domain model of the secondary side is built to analyze the relationship between transformer core imbalance and cathode voltage of secondary side rectifiers. An approximate control algorithm is designed to achieve asymmetric phase control, which reduces the effects of imbalance. A 60 V/15 A prototype is built to verify the proposed method. Experimental results show that the numerical difference of primary side peak currents between two adjacent cycles is suppressed from 2 A to approximately 0 A. Meanwhile, compared with the PCM solution, the efficiency of the PSFB converter is slightly improved from 93% to 93.2%.
Effect of Non-Idealities on the Design and Performance of a DC-DC Buck Converter
Garg, Man Mohan ; Pathak, Mukesh Kumar ; Hote, Yogesh Vijay ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 832~839
DOI : 10.6113/JPE.2016.16.3.832
In this study, the performance of a direct current (DC)-DC buck converter is analyzed in the presence of non-idealities in passive components and semiconductor devices. The effect of these non-idealities on the various design issues of a DC-DC buck converter is studied. An improved expression for duty cycle is developed to compensate the losses that occur because of the non-idealities. The design equations for inductor and capacitor calculation are modified based on this improved expression. The effect of the variation in capacitor equivalent series resistance (ESR) on output voltage ripple (OVR) is analyzed in detail. It is observed that the value of required capacitance increases with ESR. However, beyond a maximum value of ESR (r
), the capacitor is unable to maintain OVR within a specified limit. The expression of r
is derived in terms of specified OVR and inductor current ripple. Finally, these theoretical studies are validated through MATLAB simulation and experimental results.
Design of a High-Precision Constant Current AC-DC Converter with Inductance Compensation
Chang, Changyuan ; Xu, Yang ; Bian, Bin ; Chen, Yao ; Hu, Junjie ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 840~848
DOI : 10.6113/JPE.2016.16.3.840
A primary-side regulation AC-DC converter operating in the PFM (Pulse Frequency Modulation) mode with a high precision output current is designed, which applies a novel inductance compensation technique to improve the precision of the output current, which reduces the bad impact of the large tolerance of the transformer primary side inductance in the same batch. In this paper, the output current is regulated by the OSC charging current, which is controlled by a CC (constant current) controller. Meanwhile, for different primary inductors, the inductance compensation module adjusts the OSC charging current finely to improve the accuracy of the output current. The operation principle and design of the CC controller and the inductance compensation module are analyzed and illustrated herein. The control chip is implemented based on a TSMC 0.35μm 5V/40V BCD process, and a 12V/1.1A prototype has been built to verify the proposed control method. The deviation of the output current is within ±3% and the variation of the output current is less than 1% when the inductances of the primary windings vary by 10%.
Modeling and Feedback Control of LLC Resonant Converters at High Switching Frequency
Park, Hwa-Pyeong ; Jung, Jee-Hoon ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 849~860
DOI : 10.6113/JPE.2016.16.3.849
The high-switching-frequency operation of power converters can achieve high power density through size reduction of passive components, such as capacitors, inductors, and transformers. However, a small-output capacitor that has small capacitance and low effective series resistance changes the small-signal model of the converter power stage. Such a capacitor can make the converter unstable by increasing the crossover frequency in the transfer function of the small-signal model. In this paper, the design and implementation of a high-frequency LLC resonant converter are presented to verify the power density enhancement achieved by decreasing the size of passive components. The effect of small output capacitance is analyzed for stability by using a proper small-signal model of the LLC resonant converter. Finally, proper design methods of a feedback compensator are proposed to obtain a sufficient phase margin in the Bode plot of the loop gain of the converter for stable operation at 500 kHz switching frequency. A theoretical approach using MATLAB, a simulation approach using PSIM, and experimental results are presented to show the validity of the proposed analysis and design methods with 100 and 500 kHz prototype converters.
An Isolated Bidirectional Modular Multilevel DC/DC Converter for Power Electronic Transformer Applications
Wang, Zhaohui ; Zhang, Junming ; Sheng, Kuang ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 861~871
DOI : 10.6113/JPE.2016.16.3.861
With high penetration of renewable energies, power electronic transformers (PETs) will be one of the most important infrastructures in the future power delivery and management system. In this study, an isolated bidirectional modular multilevel DC/DC converter is proposed for PET applications. A modular multilevel structure is adopted as switching valves to sustain medium voltages to achieve modular design and high reliability. Only one high-frequency transformer is used in the proposed converter, which significantly simplifies the circuit and galvanic insulation design. A dual-phase-shift modulation strategy is proposed to regulate the output power and achieve a simple voltage balancing control. A down-scaled (2 kW/20 kHz) prototype is constructed to demonstrate the proposed converter and verify the control strategy. The experimental results comply with the theoretical analysis well, with the highest power efficiency reaching 97.6%.
A Novel PCCM Voltage-Fed Single-Stage Power Factor Correction Full-Bridge Battery Charger
Zhang, Taizhi ; Lu, Zhipeng ; Qian, Qinsong ; Sun, Weifeng ; Lu, Shengli ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 872~882
DOI : 10.6113/JPE.2016.16.3.872
A novel pseudo-continuous conduction mode (PCCM) voltage-fed single-stage power factor correction (PFC) full-bridge battery charger is proposed in this paper. By connecting a freewheeling transistor in parallel with an input inductor, the PFC cell can operate in the PCCM with a constant duty ratio. Thus, the dc/dc stage can be designed using this constant duty ratio and the restriction on the duty ratio of the PFC cell is eliminated. As a result, the input current distortion is less and the dc bus voltage becomes controllable over the wide output power range of the battery charger. Moreover, the operation principle of the dc/dc stage is designed to be similar to that of a conventional phase-shifted full-bridge converter. Therefore, it is easy to implement. In this paper, the operation of the new converter is explained, and the design considerations of the controller and key parameters are presented. Simulation and experimental results obtained from a 1 kW prototype are given to confirm the operation of the proposed converter.
The Impact of Parasitic Elements on Spurious Turn-On in Phase-Shifted Full-Bridge Converters
Wang, Qing ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 883~893
DOI : 10.6113/JPE.2016.16.3.883
This paper presents a comprehensive analysis of the spurious turn-on phenomena in phase-shifted full-bridge (PSFB) converters. The conventional analysis of the spurious turn-on phenomenon does not establish in the PSFB converter as realizing zero voltage switching (ZVS). Firstly, a circuit model is proposed taking into account the parasitic capacitors and inductors of the transistors, as well as the parasitic elements of the power circuit loop. Second, an exhaustive investigation into the impact of all these parasitic elements on the spurious turn-on is conducted. It has been found that the spurious turn-on phenomenon is mainly attributed to the parasitic inductors of the power circuit loop, while the parasitic inductors of the transistors have a weak impact on this phenomenon. In addition, the operation principle of the PSFB converter makes the leading and lagging legs have distinguished differences with respect to the spurious turn-on problems. Design guidelines are given based on the theoretical analysis. Finally, detailed simulation and experimental results obtained with a 1.5 kW PSFB converter are given to validate proposed analysis.
Analysis, Design, and Implementation of a Soft-Switched Active-Clamped Forward Converter with a Current-Doubler Rectifier
Jang, Paul ; Kim, Hye-Jin ; Cho, Bo-Hyung ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 894~904
DOI : 10.6113/JPE.2016.16.3.894
This study examines the zero-voltage switching (ZVS) operation of an active-clamped forward converter (ACFC) with a current-doubler rectifier (CDR). The ZVS condition can be obtained with a much smaller leakage inductance compared to that of a conventional ACFC. Due to the significantly reduced leakage inductance, the design is optimized and the circulating loss is reduced. The operation of the ACFC with a CDR is analyzed, and a detailed ZVS analysis is conducted on the basis of a steady-state analysis. From the results, a design consideration for ZVS improvement is presented. Loss analyses of the converters shows that enhanced soft-switching contributes to an efficiency improvement under light-load condition. Experimental results from a 100-W (5-V/20-A) prototype verify that the ACFC with a CDR can attain ZVS across an extended load range of loads and achieve a higher efficiency than conventional ACFCs.
Analysis, Design, and Implementation of a High-Performance Rectifier
Wang, Chien-Ming ; Tao, Chin-Wang ; Lai, Yu-Hao ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 905~914
DOI : 10.6113/JPE.2016.16.3.905
A high-performance rectifier is introduced in this study. The proposed rectifier combines the conventional pulse width modulation, soft commutation, and instantaneously average line current control techniques to promote circuit performance. The voltage stresses of the main switches in the rectifier are lower than those in conventional rectifier topologies. Moreover, conduction losses of switches in the rectifier are certainly lower than those in conventional rectifier topologies because the power current flow path when the main switches are turned on includes two main power semiconductors and the power current flow path when the main switches are turned off includes one main power semiconductor. The rectifier also adopts a ZCS-PWM auxiliary circuit to derive the ZCS function for power semiconductors. Thus, the problem of switching losses and EMI can be improved. In the control strategy, the controller uses the average current control mode to achieve fixed-frequency current control with stability and low distortion. A prototype has been implemented in the laboratory to verify circuit theory.
A Digital Self-Sustained Phase Shift Modulation Control Strategy for Full-Bridge LLC Resonant Converters
Zheng, Kai ; Zhou, Dongfang ; Li, Jianbing ; Li, Li ; Zhao, Yujing ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 915~924
DOI : 10.6113/JPE.2016.16.3.915
A digital self-sustained phase shift modulation (DSSPSM) strategy that allows for good soft switching and dynamic response performance in the presence of step variations is presented in this paper. The working principle, soft switching characteristics, and voltage gain formulae of a LLC converter with DSSPSM have been provided separately. Furthermore, the method for realizing DSSPSM is proposed. Specifically, some key components of the proposed DSSPSM are carefully investigated, including a parameter variation analysis, the start-up process, and the zero-crossing capture of the resonant current. The simulation and experiment results verify the feasibility of the proposed control method. It is observed that the zero voltage switching of the switches and the zero current switching of the rectifier diodes can be easily realized in presence of step load variations.
A New Interleaved Double-Input Three-Level Boost Converter
Chen, Jianfei ; Hou, Shiying ; Sun, Tao ; Deng, Fujin ; Chen, Zhe ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 925~935
DOI : 10.6113/JPE.2016.16.3.925
This paper proposes a new interleaved double-input three-level Boost (DITLB) converter, which is composed of two boost converters indirectly in series. Thus, a high voltage gain, together with a low component stress and a small input current ripple due to the interleaved control scheme, is achieved. The operating principle of the DITLB converter under the individual supplying power (ISP) and simultaneous supplying power (SSP) mode is analyzed. In addition, closed-loop control strategies composed of a voltage-current loop and a voltage-balance loop, have been researched to make the converter operate steadily and to alleviate the neutral-point imbalance issue. Experimental results verify correctness and feasibility of the proposed topology and control strategies.
A Singular Value Decomposition based Space Vector Modulation to Reduce the Output Common-Mode Voltage of Direct Matrix Converters
Guan, Quanxue ; Yang, Ping ; Guan, Quansheng ; Wang, Xiaohong ; Wu, Qinghua ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 936~945
DOI : 10.6113/JPE.2016.16.3.936
Large magnitude common-mode voltage (CMV) and its variation dv/dt have an adverse effect on motor drives that leads to early winding failure and bearing deterioration. For matrix converters, the switch states that connect each output line to a different input phase result in the lowest CMV among all of the valid switch states. To reduce the output CMV for matrix converters, this paper presents a new space vector modulation (SVM) strategy by utilizing these switch states. By this mean, the peak value and the root mean square of the CMV are dramatically decreased. In comparison with the conventional SVM methods this strategy has a similar computation overhead. Experiment results are shown to validate the effectiveness of the proposed modulation method.
A Novel Virtual Space Vector Modulation Strategy for the Neutral-Point Potential Comprehensive Balance of Neutral-Point-Clamped Converters
Zhang, Chuan-Jin ; Tang, Yi ; Han, Dong ; Zhang, Hui ; Zhang, Xiao ; Wang, Ke ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 946~959
DOI : 10.6113/JPE.2016.16.3.946
A novel Virtual Space Vector (VSV) modulation strategy for complete control of potential neutral point (NP) issues is proposed in this paper. The neutral point potential balancing problems of multi-level converters, which include elimination of low frequency oscillations and self-balancing for NP dc unbalance, are investigated first. Then a set of improved virtual space vectors with dynamic adjustment factors are introduced and a multi-objective optimization algorithm which aims to optimize these adjustment factors is presented in this paper. The improved virtual space vectors and the multi-objective optimization algorithm constitute the novel Virtual Space Vector modulation. The proposed novel Virtual Space Vector modulation can simultaneously recover NP dc unbalance and eliminate low frequency oscillations of the neutral point. Experiment results show that the proposed strategy has excellent performance, and that both of the neutral point potential issues can be solved.
Grid-friendly Control Strategy with Dual Primary-Side Series-Connected Winding Transformers
Shang, Jing ; Nian, Xiaohong ; Chen, Tao ; Ma, Zhenyu ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 960~969
DOI : 10.6113/JPE.2016.16.3.960
High-power three-level voltage-source converters are widely utilized in high-performance AC drive systems. In several ultra-power instances, the harmonics on the grid side should be reduced through multiple rectifications. A combined harmonic elimination method that includes a dual primary-side series-connected winding transformer and selective harmonic elimination pulse-width modulation is proposed to eliminate low-order current harmonics on the primary and secondary sides of transformers. Through an analysis of the harmonic influence caused by dead time and DC magnetic bias, a synthetic compensation control strategy is presented to minimize the grid-side harmonics in the dual primary side series-connected winding transformer application. Both simulation and experimental results demonstrate that the proposed control strategy can significantly reduce the converter input current harmonics and eliminates the DC magnetic bias in the transformer.
Modeling and Analysis of Leakage Currents in PWM-VSI-Fed PMSM Drives for Air-Conditioners with High Accuracy and within a Wide Frequency Range
Sun, Kai ; Lu, Yangjun ; Xing, Yan ; Huang, Lipei ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 970~981
DOI : 10.6113/JPE.2016.16.3.970
Leakage currents occur in pulse-width-modulated voltage source inverter (PWM-VSI)-fed permanent magnet synchronous motor (PMSM) drives for air-conditioners, which seriously affect system safety and operation performance. High accuracy modeling and prediction of leakage currents are key issues for the design and implementation of air-conditioning products. In this study, the generation mechanism of leakage currents is discussed. A systematic modeling approach of leakage currents is proposed, including the modeling of leakage current sources and leakage current paths. By using the proposed approach, the complete model of leakage currents in PWM-VSI-fed PMSM drives for air-conditioners has been developed based on the extraction of all parameters. A comparison between the simulated leakage currents based on the developed model and measured leakage currents in the outdoor unit of an air-conditioning product is conducted. The comparison verifies the effectiveness of the proposed modeling approach, and the developed model exhibits high accuracy within a wide frequency range.
Performance Evaluation of the Field-Oriented Control of Star-Connected 3-Phase Induction Motor Drives under Stator Winding Open-Circuit Faults
Jannati, Mohammad ; Idris, Nik Rumzi Nik ; Aziz, Mohd Junaidi Abdul ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 982~993
DOI : 10.6113/JPE.2016.16.3.982
A method for the fault-tolerant vector control of star-connected 3-phase Induction Motor (IM) drive systems based on Field-Oriented Control (FOC) is proposed in this paper. This method enables the control of a 3-phase IM in the presence of an open-phase failure in one of its phases without the need for control structure changes to the conventional FOC algorithm. The proposed drive system significantly reduces the speed and torque pulsations caused by an open-phase fault in the stator windings. The performance of the proposed method was verified using MATLAB (M-File) simulation as well experimental tests on a 1.5kW 3-phase IM drive system. This paper experimentally compares the operation of the proposed fault-tolerant vector controller and a conventional vector controller during open-phase fault.
Feed-Forward Approach in Stator-Flux-Oriented Direct Torque Control of Induction Motor with Space Vector Pulse-Width Modulation
Kizilkaya, Muhterem Ozgur ; Gulez, Kayhan ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 994~1003
DOI : 10.6113/JPE.2016.16.3.994
Two major obstacles in the utilization of electrical vehicles are their price and range. The collaboration of direct torque control (DTC) with induction motor (IM) is preferred for its low cost, easy implementation, and parameter independency. However, in terms of edges, the method has drawbacks, such as variable switching frequency and undesired current harmonic distortion. These drawbacks result in acoustic noise, reduced efficiency, and electromagnetic interference. A feed-forward approach for stator-flux-oriented DTC with space vector pulse-width modulation is presented in in this paper. The outcome of the proposed method is low current harmonic distortion with fixed switching frequency while preserving the torque performance and simple application feature of basic DTC. The method is applicable to existing and forthcoming IM drive systems via software adaptation. The validity of the proposed method is confirmed by simulation and experimental results.
Model Parameter Correction Algorithm for Predictive Current Control of SMPMSM
Li, Yonggui ; Wang, Shuang ; Ji, Hua ; Shi, Jian ; Huang, Surong ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1004~1011
DOI : 10.6113/JPE.2016.16.3.1004
The inaccurate model parameters in the predictive current control of surface-mounted permanent magnet synchronous motor (SMPMSM) affect the current dynamic response and steady-state error. This paper presents a model parameter correction algorithm based on the relationship between the errors of model parameters and the static errors of dq-axis current. In this correction algorithm, the errors of inductance and flux are corrected in two steps. Resistance is ignored. First, the proportional relations between inductance and d-axis static current errors are utilized to correct the error of model inductance. Second, the flux is corrected by utilizing the proportional relations between flux and q-axis static current errors under the condition that inductance is corrected. An experimental study with a 100 W SMPMSM is performed to validate the proposed algorithm.
Sensor Fault Detection, Localization, and System Reconfiguration with a Sliding Mode Observer and Adaptive Threshold of PMSM
Abderrezak, Aibeche ; Madjid, Kidouche ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1012~1024
DOI : 10.6113/JPE.2016.16.3.1012
This study deals with an on-line software fault detection, localization, and system reconfiguration method for electrical system drives composed of three-phase AC/DC/AC converters and three-phase permanent magnet synchronous machine (PMSM) drives. Current sensor failure (outage), speed/position sensor loss (disconnection), and damaged DC-link voltage sensor are considered faults. The occurrence of these faults in PMSM drive systems degrades system performance and affects the safety, maintenance, and service continuity of the electrical system drives. The proposed method is based on the monitoring signals of "abc" currents, DC-link voltage, and rotor speed/position using a measurement chain. The listed signals are analyzed and evaluated with the generated residuals and threshold values obtained from a Sliding Mode Current-Speed-DC-link Voltage Observer (SMCSVO) to acquire an on-line fault decision. The novelty of the method is the faults diagnosis algorithm that combines the use of SMCSVO and adaptive thresholds; thus, the number of false alarms is reduced, and the reliability and robustness of the fault detection system are guaranteed. Furthermore, the proposed algorithm`s performance is experimentally analyzed and tested in real time using a dSPACE DS 1104 digital signal processor board.
Design of a Low-Order Sensorless Controller by Robust H∞ Control for Boost Converters
Li, Xutao ; Chen, Minjie ; Shinohara, Hirofumi ; Yoshihara, Tsutomu ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1025~1035
DOI : 10.6113/JPE.2016.16.3.1025
Luenberger observer (LO)-based sensorless multi-loop control of a converter requires an iterative trial-and-error design process, considering that many parameters should be determined, and loop gains are indirectly related to the closed-loop characteristics. Robust H∞ control adopts a compact sensorless controller. The algebraic Riccati equation (ARE)-based and linear matrix inequality (LMI)-based H∞ approaches need an exhaustive procedure, particularly for a low-order controller. Therefore, in this study, a novel robust H∞ synthesis approach is proposed to design a low-order sensorless controller for boost converters, which need not solve any ARE or LMI, and to parameterize the controller by an adjustable parameter behaving like a "knob" on the closed-loop characteristics. Simulation results show the straightforward closed-loop characteristics evaluation and better dynamic performance by the proposed H∞ approach, compared with the LO-based sensorless multi-loop control. Practical experiments on a digital processor confirmed the simulation results.
An Active Output Filter with a Novel Control Strategy for Passive Output Filter Reduction
Choi, Kyusik ; Cho, Bo-Hyung ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1036~1045
DOI : 10.6113/JPE.2016.16.3.1036
This paper presents a novel control strategy for passive output filter reduction using an active output filter. The proposed method achieves the dual-function of regulating the output voltage ripple and output voltage variation during load transients. The novel control strategy allows traditional simple voltage controllers to be used, without requiring the expensive current sensors and complex controllers used in conventional approaches. The proposed method is verified with results from a 125-W forward converter.
Mitigation of Negative Impedance Instabilities in a DC/DC Buck-Boost Converter with Composite Load
Singh, Suresh ; Rathore, Nupur ; Fulwani, Deepak ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1046~1055
DOI : 10.6113/JPE.2016.16.3.1046
A controller to mitigate the destabilizing effect of constant power load (CPL) is proposed for a DC/DC buck-boost converter. The load profile has been considered to be predominantly of CPL type. The negative incremental resistance of the CPL tends to destabilize the feeder system, which may be an input filter or another DC/DC converter. The proposed sliding mode controller aims to ensure system stability under the dominance of CPL. The effectiveness of the controller has been validated through real-time simulation studies and experiments under various operating conditions. The controller has been demonstrated to be robust with respect to variations in supply voltage and load and capable of mitigating instabilities induced by CPL. Furthermore, the controller has been validated using all possible load profiles, which may arise in modern-day DC-distributed power systems.
A Frequency-Tracking Method Based on a SOGI-PLL for Wireless Power Transfer Systems to Assure Operation in the Resonant State
Tan, Ping-an ; He, Haibing ; Gao, Xieping ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1056~1066
DOI : 10.6113/JPE.2016.16.3.1056
Wireless power transfer (WPT) technology is now recognized as an efficient means of transferring power without physical contact. However, frequency detuning will greatly reduce the transmission power and efficiency of a WPT system. To overcome the difficulties associated with the traditional frequency-tracking methods, this paper proposes a Direct Phase Control (DPC) approach, based on the Second-Order Generalized Integrator Phase-Locked Loop (SOGI-PLL), to provide accurate frequency-tracking for WPT systems. The DPC determines the phase difference between the output voltage and current of the inverter in WPT systems, and the SOGI-PLL provides the phase of the resonant current for dynamically adjusting the output voltage frequency of the inverter. Further, the stability of this control method is analyzed using the linear system theory. The performance of the proposed frequency-tracking method is investigated under various operating conditions. Simulation and experimental results convincingly demonstrate that the proposed technique will track the quasi-resonant frequency automatically, and that the ZVS operation can be achieved.
Accurate Voltage Parameter Estimation for Grid Synchronization in Single-Phase Power Systems
Dai, Zhiyong ; Lin, Hui ; Tian, Yanjun ; Yao, Wenli ; Yin, Hang ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1067~1075
DOI : 10.6113/JPE.2016.16.3.1067
This paper presents an adaptive observer-based approach to estimate voltage parameters, including frequency, amplitude, and phase angle, for single-phase power systems. In contrast to most existing estimation methods of grid voltage parameters, in this study, grid voltage is treated as a dynamic system related to an unknown grid frequency. Based on adaptive observer theory, a full-order adaptive observer is proposed to estimate voltage parameters. A Lyapunov function-based argument is employed to ensure that the proposed estimation method of voltage parameters has zero steady-state error, even when frequency varies or phase angle jumps significantly. Meanwhile, a reduced-order adaptive observer is designed as the simplified version of the proposed full-order observer. Compared with the frequency-adaptive virtual flux estimation, the proposed adaptive observers exhibit better dynamic response to track the actual grid voltage frequency, amplitude, and phase angle. Simulations and experiments have been conducted to validate the effectiveness of the proposed observers.
A Novel Method to Suppress Mid-Frequency Vibrations with a High Speed-Loop Gain for PMSM Control
Li, Qiong ; Xu, Qiang ; Huang, Shenghua ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1076~1086
DOI : 10.6113/JPE.2016.16.3.1076
PI controllers are one of the most widely used controllers in industrial control systems due to their simple algorithms and stability. The parameters K
determine the performance of the system response. The response is expected to improve by increasing the gain of the PI controller. However, too large a gain will accelerate the speed response and cause vibrations, which is not what is expected. This paper proposes a way to suppress vibrations by detecting the vibration frequency and extracting the vibration signal as a compensation to the speed feedback. Additionally, in order to improve its disturbance rejection ability, a low-order disturbance observer is proposed. This paper also explains the operation principle of the proposed method by analyzing the transfer function and it describes the design of the controller parameters in detail. Simulation and experimental results are provided to verify the merits of the proposed method. These results also show the good performance of the proposed method. It has a rapid response and suppresses vibrations.
A Comparative Study of Two Diagnostic Methods Based on the Switching Voltage Pattern for IGBT Open-Circuit Faults in Voltage-Source Inverters
Wang, Yuxi ; Li, Zhan ; Xu, Minghui ; Ma, Hao ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1087~1096
DOI : 10.6113/JPE.2016.16.3.1087
This paper reports an investigation conducted on two diagnostic methods based on the switching voltage pattern of IGBT open-circuit faults in voltage-source inverters (VSIs). One method was based on the bridge arm pole voltage, and the other was based on bridge arm line voltage. With an additional simple circuit, these two diagnostic methods detected and effectively identified single and multiple open-circuit faults of inverter IGBTs. A comparison of the times for the diagnosis and anti-interference features between these two methods is presented. The diagnostic time of both methods was less than 280ns in the best case. The diagnostic time for the method based on the bridge arm pole voltage was less than that of the method based on the bridge arm line voltage and was 1/2 of the fundamental period in the worst case. An experimental study was carried out to show the effectiveness of and the differences between these two methods.
Fault Detection and Classification with Optimization Techniques for a Three-Phase Single-Inverter Circuit
Gomathy, V. ; Selvaperumal, S. ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1097~1109
DOI : 10.6113/JPE.2016.16.3.1097
Fault detection and isolation are related to system monitoring, identifying when a fault has occurred, and determining the type of fault and its location. Fault detection is utilized to determine whether a problem has occurred within a certain channel or area of operation. Fault detection and diagnosis have become increasingly important for many technical processes in the development of safe and efficient advanced systems for supervision. This paper presents an integrated technique for fault diagnosis and classification for open- and short-circuit faults in three-phase inverter circuits. Discrete wavelet transform and principal component analysis are utilized to detect the discontinuity in currents caused by a fault. The features of fault diagnosis are then extracted. A fault dictionary is used to acquire details about transistor faults and the corresponding fault identification. Fault classification is performed with a fuzzy logic system and relevance vector machine (RVM). The proposed model is incorporated with a set of optimization techniques, namely, evolutionary particle swarm optimization (EPSO) and cuckoo search optimization (CSO), to improve fault detection. The combination of optimization techniques with classification techniques is analyzed. Experimental results confirm that the combination of CSO with RVM yields better results than the combinations of CSO with fuzzy logic system, EPSO with RVM, and EPSO with fuzzy logic system.
An Inductance Voltage Vector Control Strategy and Stability Study Based on Proportional Resonant Regulators under the Stationary αβ Frame for PWM Converters
Sun, Qiang ; Wei, Kexin ; Gao, Chenghai ; Wang, Shasha ; Liang, Bin ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1110~1121
DOI : 10.6113/JPE.2016.16.3.1110
The mathematical model of a three phase PWM converter under the stationary αβ reference frame is deduced and constructed based on a Proportional-Resonant (PR) regulator, which can replace trigonometric function calculation, Park transformation, real-time detection of a Phase Locked Loop and feed-forward decoupling with the proposed accurate calculation of the inductance voltage vector. To avoid the parallel resonance of the LCL topology, the active damping method of the proportional capacitor-current feedback is employed. As to current vector error elimination, an optimized PR controller of the inner current loop is proposed with the zero-pole matching (ZPM) and cancellation method to configure the regulator. The impacts on system`s characteristics and stability margin caused by the PR controller and control parameter variations in the inner-current loop are analyzed, and the correlations among active damping feedback coefficient, sampling and transport delay, and system robustness have been established. An equivalent model of the inner current loop is studied via the pole-zero locus along with the pole placement method and frequency response characteristics. Then, the parameter values of the control system are chosen according to their decisive roles and performance indicators. Finally, simulation and experimental results obtained while adopting the proposed method illustrated its feasibility and effectiveness, and the inner current loop achieved zero static error tracking with a good dynamic response and steady-state performance.
A Sliding Mode Control Design based on the Reaching Law for Matrix Rectifiers
Wang, Zhiping ; Mao, Yunshou ; Hu, Zhanhu ; Xie, Yunxiang ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1122~1130
DOI : 10.6113/JPE.2016.16.3.1122
This paper presents a novel approach for achieving both a tight DC voltage regulation and a power factor control by applying the Reaching Law Sliding Mode Control (RL-SMC) and the conventional Sliding Mode Control (SMC). Applying these strategies on a matrix rectifier (MR) can achieve a unity grid side power factor when the DC load changes widely and it can provide a ripple-free output voltage that is easily affected by distortions of the three-phase ac voltage supply. Furthermore, by employing the reaching law on the SMC can solve the chatting problem of the sliding motion. Comparative Matlab simulations and experimental verifications for these strategies have been presented and discussed in this paper. The results show that by applying the SMC and RL-SMC on a MR can achieve a unity grid side power factor and a regulated ripple-free DC output.
A Novel Sliding Mode Observer for State of Charge Estimation of EV Lithium Batteries
Chen, Qiaoyan ; Jiang, Jiuchun ; Liu, Sijia ; Zhang, Caiping ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1131~1140
DOI : 10.6113/JPE.2016.16.3.1131
A simple design for a sliding mode observer is proposed for EV lithium battery SOC estimation in this paper. The proposed observer does not have the limiting conditions of existing observers. Compared to the design of previous sliding mode observers, the new observer does not require a solving matrix equation and it does not need many observers for all of the state components. As a result, it is simple in terms of calculations and convenient for engineering applications. The new observer is suitable for both time-variant and time-invariant models of battery SOC estimation, and the robustness of the new observer is proved by Liapunov stability theorem. Battery tests are performed with simulated FUDS cycles. The proposed observer is used for the SOC estimation on both unchanging parameter and changing parameter models. The estimation results show that the new observer is robust and that the estimation precision can be improved base on a more accurate battery model.
Novel Islanding Detection Method for Distributed PV Systems with Multi-Inverters
Cao, Dufeng ; Wang, Yi ; Sun, Zhenao ; Wang, Yibo ; Xu, Honghua ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1141~1151
DOI : 10.6113/JPE.2016.16.3.1141
This study proposes a novel islanding detection method for distributed photovoltaic (PV) systems with multi-inverters based on a combination of the power line carrier communication and Sandia frequency shift islanding detection methods. A parameter design method is provided for the novel scheme. On the basis of the designed parameters, the effect of frequency measurement errors and grid line impedance on the islanding detection performance of PV systems is analyzed. Experimental results show that the theoretical analysis is correct and that the novel method with the designed parameters has little effect on the power quality of the inverter output current. Non-detection zones are not observed, and a high degree of reliability is achieved. Moreover, the proposed islanding detection method is suitable for distributed PV systems with multi-inverters.
Improved Reactive Power Sharing for Parallel-operated Inverters in Islanded Microgrids
Issa, Walid ; Sharkh, Suleiman ; Mallick, Tapas ; Abusara, Mohammad ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1152~1162
DOI : 10.6113/JPE.2016.16.3.1152
The unequal impedances of the interconnecting cables between paralleled inverters in the island mode of microgrids cause inaccurate reactive power sharing when the traditional droop control is used. Many studies in the literature adopt low speed communications between the inverters and the central control unit to overcome this problem. However, the losses of this communication link can be very detrimental to the performance of the controller. This paper proposes an improved reactive power-sharing control method. It employs infrequent measurements of the voltage at the point of common coupling (PCC) to estimate the output impedance between the inverters and the PCC and then readjust the voltage droop controller gains accordingly. The controller then reverts to being a traditional droop controller using the newly calculated gains. This increases the immunity of the controller against any losses in the communication links between the central control unit and the inverters. The capability of the proposed control method has been demonstrated by simulation and experimental results using a laboratory scale microgrid.
New Techniques for Impedance Characteristics Measurement of Islanded Microgrid based on Stability Analysis
Hou, Lixiang ; Zhuo, Fang ; Shi, Hongtao ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1163~1175
DOI : 10.6113/JPE.2016.16.3.1163
In recent years, microgrids have been the focus of considerable attention in distributed energy distribution. Microgrids contain a large number of power electronic devices that can potentially cause negative impedance instability. Harmonic impedance is an important tool to analyze stability and power quality of microgrids. Harmonic impedance can also be used in harmonic source localization. Precise measurement of microgrid impedance and analysis of system stability with impedances are essential to increase stability. In this study, we introduce a new square wave current injection method for impedance measurement and stability analysis. First, three stability criteria based on impedance parameters are presented. Then, we present a new impedance measurement method for microgrids based on square wave current injection. By injecting an unbalanced line-to-line current between two lines of the AC system, the method determines all impedance information in the traditional synchronous reference frame d-q model. Finally, the microgrid impedances of each part and the overall microgrid are calculated to verify the measurement results. In the experiments, a simulation model of a three-phase AC microgrid is developed using PSCAD, and the AC system harmonic impedance measuring device is developed.
A Novel Control Scheme for T-Type Three-Level SSG Converters Using Adaptive PR Controller with a Variable Frequency Resonant PLL
Lin, Zhenjun ; Huang, Shenghua ; Wan, Shanming ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1176~1189
DOI : 10.6113/JPE.2016.16.3.1176
In this paper, a novel quasi-direct power control (Q-DPC) scheme based on a resonant frequency adaptive proportional-resonant (PR) current controller with a variable frequency resonant phase locked loop (RPLL) is proposed, which can achieve a fast power response with a unity power factor. It can also adapt to variations of the generator frequency in T-type Three-level shaft synchronous generator (SSG) converters. The PR controller under the static α-β frame is designed to track ac signals and to avert the strong cross coupling under the rotating d-q frame. The fundamental frequency can be precisely acquired by a RPLL from the generator terminal voltage which is distorted by harmonics. Thus, the resonant frequency of the PR controller can be confirmed exactly with optimized performance. Based on an instantaneous power balance, the load power feed-forward is added to the power command to improve the anti-disturbance performance of the dc-link. Simulations based on MATLAB/Simulink and experimental results obtained from a 75kW prototype validate the correctness and effectiveness of the proposed control scheme.
Classification and Compensation of DC Offset Error and Scale Error in Resolver Signals
Lee, Won ; Moon, Jong-Joo ; Im, Won-Sang ; Park, June-Ho ; Kim, Jang-Mok ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1190~1199
DOI : 10.6113/JPE.2016.16.3.1190
This study proposes a classification and compensation algorithm of two non-ideal output signals of a resolver to reduce position errors. Practically, a resolver generates position errors because of amplitude imbalance and quadrature imperfection between the two output signals of the resolver. In this study, a digital signal processor system based on a resolver-to-digital converter is used to reconstruct the two output signals of the resolver. The two output signals, "sin" and "cos," can be represented by a unit circle on the xy-plot. The classification and compensation of the errors can be obtained by using the radius and area of the circle made by the resolver signals. The method computes the integration of the areas made by the two resolver output signals to classify and compensate the error. This system cannot be applied during transient response given that the area integration during the transient state causes an error in the proposed method. The proposed method does not need any additional hardware. The experimental results verify the effectiveness of the proposed algorithm.
The Characteristics of Planar EMI Filter with Bi-Ground Layers Considering Impedance Mismatching
Wang, Shishang ; Song, Zheng ; Lou, Qianceng ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1200~1208
DOI : 10.6113/JPE.2016.16.3.1200
Planar electromagnetic interference (EMI) filter has significant engineering significance to power electronic system integration and miniaturization. However, the value of differential mode capacitance cannot meet the demand of noise suppression because of the size limit of ceramics. In this case, the EMI filter of novel multilayers is recommended to address this issue. A novel integrated structure of EMI filter based on multilayer ceramic is proposed in this study. The inductance and capacitance of the new structure can be designed separately, which is an advantage in manufacturing. Insertion loss is measured more closely to the actual situation in this study, which is different from the condition where source and load impedances are both 50 Ω. In the process of designing a novel EMI filter, noise impedance is considered. Moreover, the prototype is created and applied to a small switching power supply, which verifies the effectiveness of the developed EMI filter.
Dickson Charge Pump with Gate Drive Enhancement and Area Saving
Lin, Hesheng ; Chan, Wing Chun ; Lee, Wai Kwong ; Chen, Zhirong ; Zhang, Min ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1209~1217
DOI : 10.6113/JPE.2016.16.3.1209
This paper presents a novel charge pump scheme that combines the advantages of Fibonacci and Dickson charge pumps to obtain 30 V voltage for display driver integrated circuit application. This design only requires four external capacitors, which is suitable for a small-package application, such as smart card displays. High-amplitude (<6.6 V) clocks are produced to enhance the gate drive of a Dickson charge pump and improve the system`s current drivability by using a voltage-doubler charge pump with a pulse skip regulator. This regulation engages many middle-voltage devices, and approximately 30% of chip size is saved. Further optimization of flying capacitors tends to decrease the total chip size by 2.1%. A precise and simple model for a one-stage Fibonacci charge pump with current load is also proposed for further efficiency optimization. In a practical design, its voltage error is within 0.12% for 1 mA of current load, and it maintains a 2.83% error even for 10 mA of current load. This charge pump is fabricated through a 0.11 μm 1.5 V/6 V/32 V process, and two regulators, namely, a pulse skip one and a linear one, are operated to maintain the output of the charge pump at 30 V. The performances of the two regulators in terms of ripple, efficiency, line regulation, and load regulation are investigated.
Modeling and Analysis of an Avionic Battery Discharge Regulator
Chen, Qian ; Yu, Haihong ; Huang, Xiaoming ; Lu, Yi ; Qiu, Peng ; Tong, Kai ; Xuan, Jiazhuo ; Xu, Feng ; Xuan, Xiaohua ; Huang, Weibo ; Zhang, Yajing ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1218~1225
DOI : 10.6113/JPE.2016.16.3.1218
The avionic battery discharge regulator (BDR) plays an important role in a power-conditioning unit. With its merits of high efficiency, stable transfer function, and continuous input and output currents, the non-isolated Weinberg converter (NIWC) is suitable for avionic BDR. An improved peak current control strategy is proposed to achieve high current-sharing accuracy. Current and voltage regulators are designed based on a small signal model of a three-module NIWC system. The system with the designed regulators operates stably under any condition and achieves excellent transient response and current-sharing accuracy.
An Active Voltage Doubling Rectifier with Unbalanced-Biased Comparators for Piezoelectric Energy Harvesters
Liu, Lianxi ; Mu, Junchao ; Yuan, Wenzhi ; Tu, Wei ; Zhu, Zhangming ; Yang, Yintang ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1226~1235
DOI : 10.6113/JPE.2016.16.3.1226
For wearable health monitoring systems, a fundamental problem is the limited space for storing energy, which can be translated into a short operational life. In this paper, a highly efficient active voltage doubling rectifier with a wide input range for micro-piezoelectric energy harvesting systems is proposed. To obtain a higher output voltage, the Dickson charge pump topology is chosen in this design. By replacing the passive diodes with unbalanced-biased comparator-controlled active counterparts, the proposed rectifier minimizes the voltage losses along the conduction path and solves the reverse leakage problem caused by conventional comparator-controlled active diodes. To improve the rectifier input voltage sensitivity and decrease the minimum operational input voltage, two low power common-gate comparators are introduced in the proposed design. To keep the comparator from oscillating, a positive feedback loop formed by the capacitor C is added to it. Based on the SMIC 0.18-μm standard CMOS process, the proposed rectifier is simulated and implemented. The area of the whole chip is 0.91×0.97 mm
, while the rectifier core occupies only 13% of this area. The measured results show that the proposed rectifier can operate properly with input amplitudes ranging from 0.2 to 1.0V and with frequencies ranging from 20 to 3000 Hz. The proposed rectifier can achieve a 92.5% power conversion efficiency (PCE) with input amplitudes equal to 0.6 V at 200 Hz. The voltage conversion efficiency (VCE) is around 93% for input amplitudes greater than 0.3 V and load resistances larger than 20kΩ.
Design and Implementation of an Active EMI Filter for Common-Mode Noise Reduction
Lee, Kuk-Hee ; Kang, Byeong-Geuk ; Choi, Yongoh ; Chung, Se-Kyo ; Won, Jae-Sun ; Kim, Hee-Seung ;
Journal of Power Electronics, volume 16, issue 3, 2016, Pages 1236~1243
DOI : 10.6113/JPE.2016.16.3.1236
This paper presents the analysis and design of an active electromagnetic interference (EMI) filter (AEF) for the common-mode (CM) noise reduction of switching power converters. The features of the several types of AEFs are discussed and compared in terms of implementation. The feed-forward AEF with a voltage-sensing and voltage-cancellation (VSVC) structure is implemented for an LLC resonant converter to replace a multiple-stage passive EMI filter and thereby reduce CM noise. The characteristics and performance of the VSVC-type AEF are investigated through theoretical and experimental works.