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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 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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Accuracy Enhancement of Parameter Estimation and Sensorless Algorithms Based on Current Shaping
Kim, Jin-Woong ; Ha, Jung-Ik ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 1~8
DOI : 10.6113/JPE.2016.16.1.1
Dead time is typically incorporated in voltage source inverter systems to prevent short circuit cases. However, dead time causes an error between the output voltage and reference voltage. Hence, voltage equation-based algorithms, such as motor parameter estimation and back electromotive force (EMF)-based sensorless algorithms, are prone to estimation errors. Several dead-time compensation methods have been developed to reduce output voltage errors. However, voltage errors are still common in zero current crossing areas, and an effect of the error is much worse in a low speed region. Therefore, employing voltage equation-based algorithms in low speed regions is difficult. This study analyzes the conventional dead-time compensation method and output voltage errors in low speed operation areas. A current shaping method that can reduce output voltage errors is also proposed. Experimental results prove that the proposed method reduces voltage errors and improves the accuracy of the parameter estimation method and the performance of the back EMF-based sensorless algorithm.
Photovoltaic Modified β-Parameter-based MPPT Method with Fast Tracking
Li, Xingshuo ; Wen, Huiqing ; Jiang, Lin ; Lim, Eng Gee ; Du, Yang ; Zhao, Chenhao ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 9~17
DOI : 10.6113/JPE.2016.16.1.9
Maximum power point tracking (MPPT) is necessary for photovoltaic (PV) power system application to extract the maximum possible power under changing irradiation and temperature conditions. The β-parameter-based method has many advantages over conventional MPPT methods; such advantages include fast tracking speed in the transient stage, small oscillations in the steady state, and moderate implementation complexity. However, a problem in the implementation of the conventional beta method is the choice of an appropriate scaling factor N, which greatly affects both the steady-state and transient performance. Therefore, this paper proposes a modified β-parameter-based method, and the determination of the N is discussed in detail. The study shows that the choice of the scaling factor N is determined by the changes of the value of β during changes in irradiation or temperature. The proposed method can respond accurately and quickly during changes in irradiation or temperature. To verify the proposed method, a photovoltaic power system with MPPT function was built in Matlab/Simulink, and an experimental prototype was constructed with a solar array emulator and dSPACE. Simulation and experimental results are illustrated to show the advantages of the improved β-parameter-based method with the optimized scaling factor.
Analysis of Phase Error Effects Due to Grid Frequency Variation of SRF-PLL Based on APF
Seong, Ui-Seok ; Hwang, Seon-Hwan ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 18~26
DOI : 10.6113/JPE.2016.16.1.18
This paper proposes a compensation algorithm for reducing a specific ripple component on synchronous reference frame phase locked loop (SRF-PLL) in grid-tied single-phase inverters. In general, SRF-PLL, which is based on all-pass filter to generate virtual voltage, is widely used to estimate the grid phase angle in a single-phase system. In reality, the estimated grid phase angle might be distorted because the phase difference between actual and virtual voltages is not 90 degrees. That is, the phase error is caused by the difference between cut-off frequency of all-pass filter and grid frequency under grid frequency variation. Therefore, the effects on phase angle and output current attributed to the phase error are mathematically analyzed in this paper. In addition, the proportional resonant (PR) controller is adapted to reduce the effects of phase error. The validity of the proposed algorithm is verified through several simulations and experiments.
A Mixed SOC Estimation Algorithm with High Accuracy in Various Driving Patterns of EVs
Lim, Dong-Jin ; Ahn, Jung-Hoon ; Kim, Dong-Hee ; Lee, Byoung Kuk ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 27~37
DOI : 10.6113/JPE.2016.16.1.27
In this paper, a mixed algorithm is proposed to overcome the limitations of the conventional algorithms, which cannot be applied in various driving patterns of drivers. The proposed algorithm based on the coulomb counting method is mixed with reset algorithms that consist of the enhanced OCV reset method and the DCIR iterative calculation method. It has many advantages, such as a simple model structure, low computational overload in various profiles, and a low accumulated SOC error through the frequent SOC reset. In addition, the enhanced parameter based on a mathematical analysis of the second-order RC ladder model is calculated and is then applied to all of the methods. The proposed algorithm is verified by experimental results based on a 27-Ah LiPB. It is observed that the SOC RMSE of the proposed algorithm decreases by about 9.16% compared to the coulomb counting method.
A Droop Method for High Capacity Parallel Inverters Considering Accurate Real Power Sharing
Kim, Donghwan ; Jung, Kyosun ; Lim, Kyungbae ; Choi, Jaeho ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 38~47
DOI : 10.6113/JPE.2016.16.1.38
This paper presents DG based droop controlled parallel inverter systems with virtual impedance considering the unequal resistive-inductive combined line impedance condition. This causes a reactive power sharing error and dynamic performance degradation. Each of these drawbacks can be solved by adding the feedforward term of each line impedance voltage drop or injecting the virtual inductor. However, if the line impedances are high enough because of the long distance between the DG and the PCC or if the capacity of the system is large so that the output current is very large, this leads to a high virtual inductor voltage drop which causes reductions of the output voltage and power. Therefore, the line impedance voltage drops and the virtual inductor and resistor voltage drop compensation methods have been considered to solve these problems. The proposed method has been verified in comparison with the conventional droop method through PSIM simulation and low-scale experimental results.
Demagnetization Detection for IPM-type BLDCMs According to Irreversible Demagnetization Patterns and Pole-Slot Coefficients
Kang, Dong-Hyeok ; Kim, Hyung-Kyu ; Park, Jun-Kyu ; Hyun, Seung-Ho ; Hur, Jin ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 48~56
DOI : 10.6113/JPE.2016.16.1.48
This paper proposes a method for detecting irreversible demagnetization using the harmonic analysis of back electromotive force (BEMF) in interior permanent magnet-type brushless DC motors. First, demagnetization patterns, such as equality, inequality, and weighted demagnetizations, are defined and classified by considering the possibility of demagnetization resulting from motor operating characteristics. Second, an available diagnostic model for the harmonic analysis of BEMFs is defined according to pole-slot coefficients because the characteristics of BEMFs under demagnetization conditions are affected by the combination of poles and slots. Third, BEMFs and their harmonic components under normal and demagnetization conditions are analyzed through simulation and experiment to verify the proposed demagnetization detection technique.
Fault-Tolerant Strategy to Control a Reverse Matrix Converter for Open-Switch Faults in the Rectifier Stage
Lee, Eunsil ; Lee, Kyo-Beum ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 57~65
DOI : 10.6113/JPE.2016.16.1.57
Reverse matrix converters, which can step up voltages, are suitable for applications with source voltages that are lower than load voltages, such as generator systems. Reverse matrix converter topologies are advantageous because they do not require additional components to conventional matrix converters. In this paper, a detection method and a post-fault modulation strategy to operate a converter as close as possible to its desired normal operation under the open-switch fault condition in the rectifier stage are proposed. An open-switch fault in the rectifier stage of a reverse matrix converter causes current distortions and voltage ripples in the system. Therefore, fault-tolerant control for open-switch faults is required to improve the reliability of a system. The proposed strategy determines the appropriate switching stages from among the remaining healthy switches of the converter. This is done based on reference currents or voltages. The performance of the proposed strategy is experimentally verified.
Suppression of Leakage Current and Distortion in Variable Capacitance Devices and their Application to AC Power Regulators
Katsuki, Akihiko ; Oki, Takuya ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 66~73
DOI : 10.6113/JPE.2016.16.1.66
The quantity of alternating current (AC) leakage and the value of distortion factor in capacitor currents are discussed with regard to a new power component called variable capacitance device (VCD). This component has terminals for controlling its capacitance. Nonlinear dielectric characteristics are utilized in this device to vary the capacitance. When VCD operates in an AC circuit, the AC leakage from this device through direct current (DC) control voltage source increases according to the conditions of DC control voltage and so on. To solve this problem, we propose techniques for suppressing AC leakage. Although VCD has strong nonlinear characteristics, the current through the capacitor is not distorted significantly. The relations between AC leakage and the distortion in current waveforms are investigated. An application example for an AC power regulator is also introduced to evaluate the distortion in waveforms.
Zero-Voltage-Transition Synchronous DC-DC Converters with Coupled Inductors
Rahimi, Akbar ; Mohammadi, Mohammad Reza ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 74~83
DOI : 10.6113/JPE.2016.16.1.74
A new family of zero-voltage-transition converters with synchronous rectification is introduced in this study. Soft switching condition for all the converter operating points is provided in the proposed converters. The reverse recovery losses of the rectifier switch body diode are also eliminated. In comparison with the main switch voltage stress, the auxiliary switch voltage stress is reduced significantly. The auxiliary switch does not need the floating gate drive. The auxiliary inductor is coupled with the main converter inductor, and the leakage inductor is used as the resonance inductor. Thus, all inductors of the proposed converter can be implemented on a single core. The other features of the proposed converters include no extra voltage and current stresses on the main converter semiconductor elements. Theoretical analysis for a synchronous buck converter is presented in detail, and the validity of the theoretical analysis is justified with the experimental results of a prototype buck converter with 180 W and 80 V to 30 V.
Loss Analysis and Soft-Switching Behavior of Flyback-Forward High Gain DC/DC Converters with a GaN FET
Li, Yan ; Zheng, Trillion Q. ; Zhang, Yajing ; Cui, Meiting ; Han, Yang ; Dou, Wei ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 84~92
DOI : 10.6113/JPE.2016.16.1.84
Compared with Si MOSFETs, the GaN FET has many advantages in a wide band gap, high saturation drift velocity, high critical breakdown field, etc. This paper compares the electrical properties of GaN FETs and Si MOSFETs. The soft-switching condition and power loss analysis in a flyback-forward high gain DC/DC converter with a GaN FET is presented in detail. In addition, a comparison between GaN diodes and Si diodes is made. Finally, a 200W GaN FET based flyback-forward high gain DC/DC converter is established, and experimental results verify that the GaN FET is superior to the Si MOSFET in terms of switching characteristics and efficiency. They also show that the GaN diode is better than the Si diode when it comes to reverse recovery characteristics.
Full ZVS Load Range Diode Clamped Three-level DC-DC Converter with Secondary Modulation
Shi, Yong ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 93~101
DOI : 10.6113/JPE.2016.16.1.93
A new four-primary-switch diode clamped soft switching three-level DC-DC converter (TLDC) with full zero-voltage switching (ZVS) load range and TL secondary voltage waveform is proposed. The operation principle and characteristics of the presented converter are discussed, and experimental results are consistent with theoretical predictions. The improvements of the proposed converter include a simple and compact primary structure, TL secondary rectified voltage waveform, wide load range ZVS for all primary switches, and full output-regulated range with soft switching operation. The proposed converter also has some disadvantages. The VA rating of the transformer is slightly larger than that of conventional TLDCs in variable input and constant output mode. The conduction loss of the primary coil is slightly higher because an air gap is inserted into the magnetic cores of the transformer. Finally, the secondary circuit is slightly complex.
Contactless Power Charger for Light Electric Vehicles Featuring Active Load Matching
Jiang, Wei ; Xu, Song ; Li, Nailu ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 102~110
DOI : 10.6113/JPE.2016.16.1.102
Contactless power transfer technology is gaining increasing attention in city transportation applications because of its high mobility and flexibility in charging and its commensurate power level with conductive power transfer method. In this study, an inductively coupled contactless charging system for a 48 V light electric vehicle is proposed. Although this study does not focus on system efficiency, the generic problems in an inductively coupled contactless power transfer system without ferromagnetic structure are discussed. An active load matching method is also proposed to control the power transfer on the receiving side through a load matching converter. Small signal modeling and linear control technology are applied to the load matching converter for port voltage regulation, which effectively controls the power flow into the load. A prototype is built, and experiments are conducted to reveal the intrinsic characteristics of a series-series resonant inductive power charger in terms of frequency, air gap length, power flow control, coil misalignment, and efficiency issues.
A Novel IPT System Based on Dual Coupled Primary Tracks for High Power Applications
Li, Yong ; Mai, Ruikun ; Lu, Liwen ; He, Zhengyou ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 111~120
DOI : 10.6113/JPE.2016.16.1.111
Generally, a single phase H-bridge converter feeding a single primary track is employed in conventional inductive power transfer systems. However, these systems may not be suitable for some high power applications due to the constraints of the semiconductor switches and the cost. To resolve this problem, a novel dual coupled primary tracks IPT system consisting of two high frequency resonant inverters feeding the tracks is presented in this paper. The primary tracks are wound around an E-shape ferrite core in parallel which enhances the magnetic flux around the tracks. The mutual inductance of the coupled tracks is utilized to achieve adjustable power sharing between the inverters by configuring the additional resonant capacitors. The total transfer power can be continuously regulated by altering the pulse width of the inverters' output voltage with the phase shift control approach. In addition, the system's efficiency and the control strategy are provided to analyze the characteristic of the proposed IPT system. An experimental setup with total power of 1.4kW is employed to verify the proposed system under power ratios of 1:1 and 1:2 with a transfer efficiency up to 88.7%. The results verify the performance of the proposed system.
Optimal Design Methodology of Zero-Voltage-Switching Full-Bridge Pulse Width Modulated Converter for Server Power Supplies Based on Self-driven Synchronous Rectifier Performance
Cetin, Sevilay ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 121~132
DOI : 10.6113/JPE.2016.16.1.121
In this paper, high-efficiency design methodology of a zero-voltage-switching full-bridge (ZVS-FB) pulse width modulation (PWM) converter for server-computer power supply is discussed based on self-driven synchronous rectifier (SR) performance. The design approach focuses on rectifier conduction loss on the secondary side because of high output current application. Various-number parallel-connected SRs are evaluated to reduce high conduction loss. For this approach, the reliability of gate control signals produced from a self-driver is analyzed in detail to determine whether the converter achieves high efficiency. A laboratory prototype that operates at 80 kHz and rated 1 kW/12 V is built for various-number parallel combination of SRs to verify the proposed theoretical analysis and evaluations. Measurement results show that the best efficiency of the converter is 95.16%.
A Novel Five-Level Flying-Capacitor Dual Buck Inverter
Liu, Miao ; Hong, Feng ; Wang, Cheng-Hua ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 133~141
DOI : 10.6113/JPE.2016.16.1.133
This paper focuses on the development of a Five-Level Flying-Capacitor Dual Buck Inverter (FLFCDBI) based on the main circuit of dual buck inverters. This topology has been described as not having any shoot-through problems, no body-diode reverse recovery problems and the half-cycle work mode found in the traditional Multi-Level Flying-Capacitor Inverter (MLFCI). It has been shown that the flying-capacitor voltages of this inverter can be regulated by the redundant state selection within one pole. The voltage balance of the flying-capacitors can be achieved by charging or discharging in the positive (negative) half cycles by choosing the proper logical algorithms. This system has a simple structure but demonstrates improved performance and reliability. The validity of this inverter is conformed through computer-aided simulation and experimental investigations.
Carrier Based Common Mode Voltage Reduction Techniques in Neutral Point Clamped Inverter Based AC-DC-AC Drive System
Ojha, Amit ; Chaturvedi, Pradyumn ; Mittal, Arvind ; Jain, Shailendra ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 142~152
DOI : 10.6113/JPE.2016.16.1.142
Common mode voltage (CMV) generation is a major problem in switching power converter fed induction motor drive systems. CMV is the zero sequence voltage generated due to the switching action of power converters. Even a small magnitude of CMV with a high rate of change may circulate large bearing currents which may damage a machine's bearings and shorten its life. There are several methods of controlling CMV. This paper presents 3-level sinusoidal pulse width modulation based techniques to control the magnitude and rate of change of CMV in multilevel AC-DC-AC drive systems. Simulation and experimental investigations have been presented to validate the performance of proposed technique to control CMV in 3-level neutral point clamped inverter based AC-DC-AC system.
Simple Technique Reducing Leakage Current for H-Bridge Converter in Transformerless Photovoltaic Generation
Kot, Radoslaw ; Stynski, Sebastian ; Stepien, Krzysztof ; Zaleski, Jaroslaw ; Malinowski, Mariusz ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 153~162
DOI : 10.6113/JPE.2016.16.1.153
Given their structural arrangement, photovoltaic (PV) modules exhibit parasitic capacitance, which creates a path for high-frequency current during zero-state switching of the converter in transformerless systems. This current has to be limited to ensure safety and electromagnetic compatibility. Many solutions that can minimize or completely avoid this phenomenon, are available. However, most of these solutions are patented because they rely on specific and often complex converter topologies. This study aims to solve this problem by introducing a solution based on a classic converter topology with an appropriate modulation technique and passive filtering. A 5.5 kW single-phase residential PV system that consists of DC-DC boost stage and DC-AC H-bridge converter is considered. Control schemes for both converter stages are presented. An overview of existing modulation techniques for H-bridge converter is provided, and a modification of hybrid modulation is proposed. A system prototype is built for the experimental verification. As shown in the study, with simple filtering and proper selection of switching states, achieving low leakage current level is possible while maintaining high converter efficiency and required energy quality.
Modulation, Harmonic Analysis, and Balancing Control for a New Modular Multilevel Converter
Li, Binbin ; Zhang, Yi ; Wang, Gaolin ; Xu, Dianguo ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 163~172
DOI : 10.6113/JPE.2016.16.1.163
The modular multilevel converter (MMC) has been receiving increased attentions in recent years. The new modular multilevel converter is a derivative topology from the traditional MMC in which the number of sub-modules (SMs) necessitated by each phase can be reduced by one. This paper presents a phase-shifted carrier pulse-width modulation (PSC-PWM) for the new MMC with an optimal phase-shifted angle to suppress the harmonics of the output voltage. Further, the harmonic features when the capacitor voltage of the middle SM is selected as two different values are also investigated. Moreover, in order to avoid introducing an unnecessary dc offset current at the ac terminals of the new MMC, a novel capacitor voltage balancing scheme is proposed by adjusting the amplitude of the reference signals rather than the offset. Finally, the validity and effectiveness of the proposed modulation and balancing schemes have been verified by experimental results based on a three-phase prototype of the new MMC.
Converter Utilization Ratio Enhancement in the THD Optimization of Cascaded H-Bridge 7-level Inverters
Khamooshi, Reza ; Namadmalan, Alireza ; Moghani, Javad Shokrollahi ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 173~181
DOI : 10.6113/JPE.2016.16.1.173
In this paper, a new technique for harmonic optimization in cascaded H-bridge 7-level inverters is proposed. The suggested strategy is based on minimizing an objective function which simultaneously optimizes the converter utilization and Total Harmonic Distortion (THD). The Switch Utilization Ratio (SUR) is formulized for both the phase and line-line voltages of a 7-level inverter and is considered in the final objective functions. Based upon the SUR formula, utilization ratio enhancement will reduce the value of feeding DC links, which improves the efficiency and lifetime of the circuit components due to lower voltage stresses and losses. In order to achieve more effective solution in different modulation indices, it is assumed that the DC sources can be altered. Experimental validation is presented based on a three-phase 7-level inverter prototype.
Fault Detection of a Proposed Three-Level Inverter Based on a Weighted Kernel Principal Component Analysis
Lin, Mao ; Li, Ying-Hui ; Qu, Liang ; Wu, Chen ; Yuan, Guo-Qiang ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 182~189
DOI : 10.6113/JPE.2016.16.1.182
Fault detection is the research focus and priority in this study to ensure the high reliability of a proposed three-level inverter. Kernel principal component analysis (KPCA) has been widely used for feature extraction because of its simplicity. However, highlighting useful information that may be hidden under retained KPCs remains a problem. A weighted KPCA is proposed to overcome this shortcoming. Variable contribution plots are constructed to evaluate the importance of each KPC on the basis of sensitivity analysis theory. Then, different weighting values of KPCs are set to highlight the useful information. The weighted statistics are evaluated comprehensively by using the improved feature eigenvectors. The effectiveness of the proposed method is validated. The diagnosis results of the inverter indicate that the proposed method is superior to conventional KPCA.
PI Controlled Active Front End Super-Lift Converter with Ripple Free DC Link for Three Phase Induction Motor Drives
Elangovan, P. ; Mohanty, Nalin Kant ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 190~204
DOI : 10.6113/JPE.2016.16.1.190
An active front end (AFE) is required for a three-phase induction motor (IM) fed by a voltage source inverter (VSI), because of the increasing need to derive quality current from the utility end without sacrificing the power factor (PF). This study investigates a proportional-plus-integral (PI) controller based AFE topology that uses a super-lift converter (SLC). The significance of the proposed SLC, which converts rectified AC supply to geometrically proceed ripple-free DC supply, is explained. Variations in several power quality parameters in the intended IM drive for 0% and 100% loading conditions are demonstrated. A simulation is conducted by using MATLAB/Simulink software, and a prototype is built with a field programmable gate array (FPGA) Spartan-6 processor. Simulation results are correlated with the experimental results obtained from a 0.5 HP IM drive prototype with speed feedback and a voltage/frequency (V/f) control strategy. The proposed AFE topology using SLC is suitable for three-phase IM drives, considering the supply end PF, the DC-link voltage and current, the total harmonic distortion (THD) in supply current, and the speed response of IM.
Intelligent Position Control of a Vertical Rotating Single Arm Robot Using BLDC Servo Drive
Manikandan, R. ; Arulmozhiyal, R. ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 205~216
DOI : 10.6113/JPE.2016.16.1.205
The manufacturing sector resorts to automation to increase production and homogeneity of products during mass production, without increasing scarce, expensive, and unreliable manpower. Automation in the form of multiple robotic arms that handle materials in all directions in different stages of the process is proven to be the best way to increase production. This paper thoroughly investigates robotic single-arm movements, that is, 360° vertical rotation, with the help of a brushless DC motor, controlled by a fuzzy proportional-integral-derivative (PID) controller. This paper also deals with the design and performance of the fuzzy-based PID controller used to control vertical movement against the limited scope of conventional PID feedback controller and how the torque of the arm is affected by the fuzzy PID controller in the four quadrants to ensure constant speed and accident-free operation despite the influence of gravitational force. The design was simulated through MATLAB/SIMULINK and integrated with dSPACE DS1104-based hardware to verify the dynamic behaviors of the arm.
Analysis of Real-Time Estimation Method Based on Hidden Markov Models for Battery System States of Health
Piao, Changhao ; Li, Zuncheng ; Lu, Sheng ; Jin, Zhekui ; Cho, Chongdu ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 217~226
DOI : 10.6113/JPE.2016.16.1.217
A new method is proposed based on a hidden Markov model (HMM) to estimate and analyze battery states of health. Battery system health states are defined according to the relationship between internal resistance and lifetime of cells. The source data (terminal voltages and currents) can be obtained from vehicular battery models. A characteristic value extraction method is proposed for HMM. A recognition framework and testing datasets are built to test the estimation rates of different states. Test results show that the estimation rates achieved based on this method are above 90% under single conditions. The method achieves the same results under hybrid conditions. We can also use the HMMs that correspond to hybrid conditions to estimate the states under a single condition. Therefore, this method can achieve the purpose of the study in estimating battery life states. Only voltage and current are used in this method, thereby establishing its simplicity compared with other methods. The batteries can also be tested online, and the method can be used for online prediction.
Digitally Current Controlled DC-DC Switching Converters Using an Adjacent Cycle Sampling Strategy
Wei, Tingcun ; Wang, Yulin ; Li, Feng ; Chen, Nan ; Wang, Jia ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 227~237
DOI : 10.6113/JPE.2016.16.1.227
A novel digital current control strategy for digitally controlled DC-DC switching converters, referred to as Adjacent Cycle Sampling (ACS), is proposed in this paper. For the ACS current control strategy, the available time interval from sampling the current to updating the duty ratio, is approximately one switching cycle. In addition, it is independent of the duty ratio. As a result, the contradiction between the processing speed of the hardware and the transient response speed can be effectively relaxed by using the ACS current control strategy. For digitally controlled buck DC-DC switching converters with trailing-edge modulation, digital current control algorithms with the ACS control strategy are derived for three different control objectives. These objectives are the valley, average, and peak inductor currents. In addition, the sub-harmonic oscillations of the above current control algorithms are analyzed and eliminated by using the digital slope compensation (DSC) method. Experimental results based on a FPGA are given, which verify the theoretical analysis results very well. It can be concluded that the ACS control has a faster transient response speed than the time delay control, and that its requirements for hardware processing speed can be reduced when compared with the deadbeat control. Therefore, it promises to be one of the key technologies for high-frequency DC-DC switching converters.
State Estimation Technique for VRLA Batteries for Automotive Applications
Duong, Van Huan ; Tran, Ngoc Tham ; Choi, Woojin ; Kim, Dae-Wook ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 238~248
DOI : 10.6113/JPE.2016.16.1.238
The state-of-charge (SOC) and state-of-health (SOH) estimation of batteries play important roles in managing batteries for automotive applications. However, an accurate state estimation of a battery is difficult to achieve because of certain factors, such as measurement noise, highly nonlinear characteristics, strong hysteresis phenomenon, and diffusion effect of batteries. In certain vehicular applications, such as idle stop-start systems (ISSs), significant errors in SOC/SOH estimation may lead to a failure in restarting a combustion engine after the shut-off period of the engine when the vehicle is at rest, such as at a traffic light. In this paper, a dual extended Kalman filter algorithm with a dynamic equivalent circuit model of a lead-acid battery is proposed to deal with this problem. The proposed algorithm adopts a battery model by taking into account the hysteresis phenomenon, diffusion effect, and parameter variations for accurate state estimations of the battery. The validity of the proposed algorithm is verified through experiments by using an absorbed glass mat valve-regulated lead-acid battery and a battery sensor cable for commercial ISS vehicles.
Low-frequency Vibration Suppression Control in a Two-mass System by Using a Torque Feed-forward and Disturbance Torque Observer
Li, Qiong ; Xu, Qiang ; Wu, Ren ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 249~258
DOI : 10.6113/JPE.2016.16.1.249
Given that elastic connection is often used between motor drives and load devices in industrial applications, vibration often occurs at the load side. Vibration suppression is a crucial problem that needs to be addressed to achieve a high-performance servo-control system. Scholars have presented many strategies to suppress vibration. In this study, we propose a method to diminish vibration by using a torque feed-forward and disturbance torque observer. We analyze the system performance and explain the principle of the proposed vibration suppression method based on the transfer functions of the system. The design of controller parameters is another important issue in practical applications. We accordingly provide a succinct outline of the design specifications based on the coefficient diagram method. Furthermore, we build a model under the Simulink environment and conduct experiments to validate the proposed method. Results show that speed and position vibrations are successfully suppressed by the proposed method.
Control Design of the Brushless Doubly-Fed Machines for Stand-Alone VSCF Ship Shaft Generator Systems
Liu, Yi ; Ai, Wu ; Chen, Bing ; Chen, Ke ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 259~267
DOI : 10.6113/JPE.2016.16.1.259
This paper presents a stand-alone variable speed constant frequency (VSCF) ship shaft generator system based on a brushless doubly-fed machine (BDFM). In this system, the output voltage amplitude and frequency of the BDFM are kept constant under a variable rotor speed and load by utilizing a well-designed current vector controller to regulate the control winding (CW) current. The control scheme is proposed, and the hardware design for the control system is developed. The proposed generator system is tested on a 325 TEU container vessel, and the test results show the good dynamic performance of the CW current vector controller and the whole control system. A harmonic analysis of the output voltage and a fuel consumption analysis of the generator system are also implemented. Finally, the total efficiency of the generator system is presented under different rotor speeds and load conditions.
Hybrid Sinusoidal-Pulse Charging Method for the Li-Ion Batteries in Electric Vehicle Applications Based on AC Impedance Analysis
Hu, Sideng ; Liang, Zipeng ; He, Xiangning ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 268~276
DOI : 10.6113/JPE.2016.16.1.268
A hybrid sinusoidal-pulse current (HSPC) charging method for the Li-ion batteries in electric vehicle applications is proposed in this paper. The HSPC charging method is based on the Li-ion battery ac-impedance spectrum analysis, while taking into account the high power requirement and system integration. The proposed HSPC method overcomes the power limitation in the sinusoidal ripple current (SRC) charging method. The charger shares the power devices in the motor inverter for hardware cost saving. Phase shifting in multiple pulse currents is employed to generate a high frequency multilevel charging current. Simulation and experimental results show that the proposed HSPC method improves the charger efficiency related to the hardware and the battery energy transfer efficiency.
Novel Predictive Maximum Power Point Tracking Techniques for Photovoltaic Applications
Abdel-Rahim, Omar ; Funato, Hirohito ; Haruna, Junnosuke ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 277~286
DOI : 10.6113/JPE.2016.16.1.277
This paper offers two Maximum Power Point Tracking (MPPT) systems for Photovoltaic (PV) applications. The first MPPT method is based on a fixed frequency Model Predictive Control (MPC). The second MPPT technique is based on the Predictive Hysteresis Control (PHC). An experimental demonstration shows that the proposed techniques are fast, accurate and robust in tracking the maximum power under different environmental conditions. A DC/DC converter with a high voltage gain is obligatory to track PV applications at the maximum power and to boost a low voltage to a higher voltage level. For this purpose, a high gain Switched Inductor Quadratic Boost Converter (SIQBC) for PV applications is presented in this paper. The proposed converter has a higher gain than the other transformerless topologies in the literature. It is shown that at a high gain the proposed SIQBC has moderate efficiency.
Improved Global Maximum Power Point Tracking for Photovoltaic System via Cuckoo Search under Partial Shaded Conditions
Shi, Ji-Ying ; Xue, Fei ; Qin, Zi-Jian ; Zhang, Wen ; Ling, Le-Tao ; Yang, Ting ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 287~296
DOI : 10.6113/JPE.2016.16.1.287
Conventional maximum power point tracking (MPPT) methods are ineffective under partially shaded conditions because multiple local maximum can be exhibited on power-voltage characteristic curve. This study proposes an improved cuckoo search (ICS) MPPT method after investigating the cuckoo search (CS) algorithm applied in solving multiple MPPT. The algorithm eliminates the random step in the original CS algorithm, and the conception of low-power, high-power, normal and marked zones are introduced. The adaptive step adjustment is also realized according to the different stages of the nest position. This algorithm adopts the large step in low-power and marked zones to reduce search time, and a small step in high-power zone is used to improve search accuracy. Finally, simulation and experiment results indicate that the promoted ICS algorithm can immediately and accurately track the global maximum under partially shaded conditions, and the array output efficiency can be improved.
Stationary Frame Current Control Evaluations for Three-Phase Grid-Connected Inverters with PVR-based Active Damped LCL Filters
Han, Yang ; Shen, Pan ; Guerrero, Josep M. ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 297~309
DOI : 10.6113/JPE.2016.16.1.297
Grid-connected inverters (GCIs) with an LCL output filter have the ability of attenuating high-frequency (HF) switching ripples. However, by using only grid-current control, the system is prone to resonances if it is not properly damped, and the current distortion is amplified significantly under highly distorted grid conditions. This paper proposes a synchronous reference frame equivalent proportional-integral (SRF-EPI) controller in the αβ stationary frame using the parallel virtual resistance-based active damping (PVR-AD) strategy for grid-interfaced distributed generation (DG) systems to suppress LCL resonance. Although both a proportional-resonant (PR) controller in the αβ stationary frame and a PI controller in the dq synchronous frame achieve zero steady-state error, the amplitude- and phase-frequency characteristics differ greatly from each other except for the reference tracking at the fundamental frequency. Therefore, an accurate SRF-EPI controller in the αβ stationary frame is established to achieve precise tracking accuracy. Moreover, the robustness, the harmonic rejection capability, and the influence of the control delay are investigated by the Nyquist stability criterion when the PVR-based AD method is adopted. Furthermore, grid voltage feed-forward and multiple PR controllers are integrated into the current loop to mitigate the current distortion introduced by the grid background distortion. In addition, the parameters design guidelines are presented to show the effectiveness of the proposed strategy. Finally, simulation and experimental results are provided to validate the feasibility of the proposed control approach.
A New Orthogonal Signal Generator with DC Offset Rejection for Single-Phase Phase Locked Loops
Huang, Xiaojiang ; Dong, Lei ; Xiao, Furong ; Liao, Xiaozhong ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 310~318
DOI : 10.6113/JPE.2016.16.1.310
This paper presents a new orthogonal signals generator (OSG) with DC Offset rejection for implementing a phase locked loop (PLL) in single-phase grid-connected power systems. An adaptive filter (AF) based on the least mean square (LMS) algorithm is used to constitute the OSG in this study. The DC offset in the measured grid voltage signal can be significantly rejected in the developed OSG technique. This generates two pure orthogonal signals that are free from the DC offset. As a result, the DC offset rejection performance of the presented single-phase phase locked loop (SPLL) can be enhanced. A mathematical model of the developed OSG and the principle of the adaptive filter based SPLL (AF-SPLL) are presented in detail. Finally, simulation and experimental results demonstrate the feasibility of the proposed AF-SPLL.
On DC-Side Impedance Frequency Characteristics Analysis and DC Voltage Ripple Prediction under Unbalanced Conditions for MMC-HVDC System Based on Maximum Modulation Index
Liu, Yiqi ; Chen, Qichao ; Li, Ningning ; Xie, Bing ; Wang, Jianze ; Ji, Yanchao ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 319~328
DOI : 10.6113/JPE.2016.16.1.319
In this study, we first briefly introduce the effect of circulating current control on the modulation signal of a modular multilevel converter (MMC). The maximum modulation index is also theoretically derived. According to the optimal modulation index analysis and the model in the continuous domain, different DC-side output impedance equivalent models of MMC with/without compensating component are derived. The DC-side impedance of MMC inverter station can be regarded as a series xR + yL + zC branch in both cases. The compensating component of the maximum modulation index is also related to the DC equivalent impedance with circulating current control. The frequency characteristic of impedance for MMC, which is observed from its DC side, is analyzed. Finally, this study investigates the prediction of the DC voltage ripple transfer between two-terminal MMC high-voltage direct current systems under unbalanced conditions. The rationality and accuracy of the impedance model are verified through MATLAB/Simulink simulations and experimental results.
Secondary Voltage Control for Reactive Power Sharing in an Islanded Microgrid
Guo, Qian ; Wu, Hongyan ; Lin, Liaoyuan ; Bai, Zhihong ; Ma, Hao ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 329~339
DOI : 10.6113/JPE.2016.16.1.329
Owing to mismatched feeder impedances in an islanded microgrid, the conventional droop control method typically results in errors in reactive power sharing among distributed generation (DG) units. In this study, an improved droop control strategy based on secondary voltage control is proposed to enhance the reactive power sharing accuracy in an islanded microgrid. In a DG local controller, an integral term is introduced into the voltage droop function, in which the voltage compensation signal from the secondary voltage control is utilized as the common reactive power reference for each DG unit. Therefore, accurate reactive power sharing can be realized without any power information exchange among DG units or between DG units and the central controller. Meanwhile, the voltage deviation in the microgrid common bus is removed. Communication in the proposed strategy is simple to implement because the information of the voltage compensation signal is broadcasted from the central controller to each DG unit. The reactive power sharing accuracy is also not sensitive to time-delay mismatch in the communication channels. Simulation and experimental results are provided to validate the effectiveness of the proposed method.
A Cascaded Hybrid Multilevel Inverter Incorporating a Reconfiguration Technique for Low Voltage DC Distribution Applications
Khomfoi, Surin ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 340~350
DOI : 10.6113/JPE.2016.16.1.340
A cascaded hybrid multilevel inverter including a reconfiguration technique for low voltage dc distribution applications is proposed in this paper. A PWM generation fault detection and reconfiguration paradigm after an inverter cell fault are developed by using only a single-chip controller. The proposed PWM technique is also modified to reduce switching losses. In addition, the proposed topology can reduce the number of required power switches compared to the conventional cascaded multilevel inverter. The proposed technique is validated by using a 3-kVA prototype. The switching losses of the proposed multilevel inverter are also investigated. The experimental results show that the proposed hybrid inverter can improve system efficiency, reliability and cost effectiveness. The efficiency of proposed system is 97.45% under the tested conditions. The proposed hybrid inverter topology is a promising method for low voltage dc distribution and can be applied for the multiple loads which are required in a data center or telecommunication building.
High-Performance Control of Three-Phase Four-Wire DVR Systems using Feedback Linearization
Jeong, Seon-Yeong ; Nguyen, Thanh Hai ; Le, Quoc Anh ; Lee, Dong-Choon ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 351~361
DOI : 10.6113/JPE.2016.16.1.351
Power quality is a critical issue in distribution systems, where a dynamic voltage restorer (DVR) is commonly used to mitigate the voltage disturbances for loads. This paper deals with a nonlinear control for the three-phase four-wire (3P-4W) DVR under a grid voltage unbalance and nonlinear loads in the distribution system, where a novel control scheme based on the feedback linearization technique is proposed. Through feedback linearization, a nonlinear model of a DVR with a PWM voltage-source inverter (VSI) and LC filters is linearized. Then, the controller design of the linearized model is performed by applying the linear control theory, where the load voltages are kept constant by controlling the d-q-0 axis components of the DVR output voltages. To keep the load voltage unchanged, an in-phase compensation strategy is employed, where the load voltages are recovered to be the same as the previous voltage without a change in the magnitude. With this strategy, the performance of the DVR becomes faster and more stable even under unbalanced source voltages and nonlinear loads. The validity of the proposed control strategy has been verified by simulation and experimental results.
Research of an On-Line Measurement Method for High-power IGBT Collector Current
Hu, Liangdeng ; Sun, Chi ; Zhao, Zhihua ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 362~373
DOI : 10.6113/JPE.2016.16.1.362
The on-line measurement of high-power IGBT collector current is important for the hierarchical control and short-circuit and overcurrent protection of its driver and the sensorless control of the converter. The conventional on-line measurement methods for IGBT collector current are not suitable for engineering measurement due to their large-size, high-cost, low-efficiency sensors, current transformers or dividers, etc. Based on the gate driver, this paper has proposed a current measuring circuit for IGBT collector current. The circuit is used to conduct non-intervention on-line measurement of IGBT collector current by detecting the voltage drop of the IGBT power emitter and the auxiliary emitter terminals. A theoretical analysis verifies the feasibility of this circuit. The circuit adopts an operational amplifier for impedance isolation to prevent the measuring circuit from affecting the dynamic performance of the IGBT. Due to using the scheme for integration first and amplification afterwards, the difficult problem of achieving high accuracy in the transient-state and on-state measurement of the voltage between the terminals of IGBT power emitter and the auxiliary emitter (u
) has been solved. This is impossible for a conventional detector. On this basis, the adoption of a two-stage operational amplifier can better meet the requirements of high bandwidth measurement under the conditions of a small signal with a large gain. Finally, various experiments have been carried out under the conditions of several typical loads (resistance-inductance load, resistance load and inductance load), different IGBT junction temperatures, soft short-circuits and hard short-circuits for the on-line measurement of IGBT collector current. This is aided by the capacitor voltage which is the integration result of the voltage uEe. The results show that the proposed method of measuring IGBT collector current is feasible and effective.
An Improved Analytical Model for Predicting the Switching Performance of SiC MOSFETs
Liang, Mei ; Zheng, Trillion Q. ; Li, Yan ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 374~387
DOI : 10.6113/JPE.2016.16.1.374
This paper derives an improved analytical model to estimate switching loss and analyze the effects of parasitic elements on the switching performance of SiC MOSFETs. The proposed analytical model considers the parasitic inductances, the nonlinearity of the junction capacitances and the nonlinearity of the trans-conductance. The turn-on process and the turn-off process are illustrated in detail, and equivalent circuits are derived and solved for each switching transition. The proposed analytical model is more accurate and matches better with experimental results than other analytical models. Note that switching losses calculated based on experiments are imprecise, because the energy of the junction capacitances is not properly disposed. Finally, the proposed analytical model is utilized to account for the effects of parasitic elements on the switching performance of a SiC MOSFET, and the circuit design rules for high frequency circuits are given.
Voltage Source Inverter Drive Using Error-compensated Pulse Width Modulation
Chen, Keng-Yuan ; Hu, Jwu-Sheng ; Lin, Jau-Nan ;
Journal of Power Electronics, volume 16, issue 1, 2016, Pages 388~397
DOI : 10.6113/JPE.2016.16.1.388
An error-compensated pulse width modulator (ECPWM) is proposed to improve the baseband harmonic performance and the switching loss of voltage source inverters (VSIs). Selecting between harmonic distortion and switching loss is a design tradeoff in the conventional space vector pulse width modulation. In this work, an accumulated difference in produced and desired phase voltages is considered to adjust the reference signal. This mechanism can compensate for the voltage error in the previous carrier period. With error compensation every half-carrier period, the proposed ECPWM allows one-half reduction in carrier frequency without scarifying baseband harmonic distortion. The proposed modulator is applied to a three-phase VSI with R-L load and a motor-speed-control system for experiments. The measured efficiency and operating temperature of switches confirm the effectiveness of the proposed scheme.