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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Power Electronics
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The Korean Institute of Power Electronics
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Volume & Issues
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 Modular Bi-Directional Power Electronic Transformer
Gao, Zhigang ; Fan, Hui ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 399~413
DOI : 10.6113/JPE.2016.16.2.399
This paper presents a topology for a modular power electronic transformer (PET) and a control scheme. The proposed PET consists of a cascaded H-Bridge rectifier on the primary side, a high-frequency DC/DC conversion cell in the center, and a cascaded H-Bridge inverter on the secondary side. It is practical to use PETs in power systems to reduce the cost, weight and size. A detailed analysis of the structure is carried out by using equivalent circuit. An algorithm to control the voltages of each capacitor and to maintain the power flow in the PET is established. The merits are analyzed and verified in theory, including the bi-directional power flow, variable voltage/frequency and high power factor on the primary side. The experimental results validated the propose structure and algorithm.
A High-Efficiency High Step-Up Interleaved Converter with a Voltage Multiplier for Electric Vehicle Power Management Applications
Tseng, Kuo-Ching ; Chen, Chun-Tse ; Cheng, Chun-An ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 414~424
DOI : 10.6113/JPE.2016.16.2.414
This paper proposes a novel high-efficiency high-step-up interleaved converter with a voltage multiplier, which is suitable for electric vehicle power management applications. The proposed interleaved converter is capable of achieving high step-up conversion by employing a voltage-multiplier circuit. The proposed converter lowers the input-current ripple, which can extend the input source's lifetime, and reduces the voltage stress on the main switches. Hence, large voltage spikes across the main switches are alleviated and the efficiency is improved. Finally, a prototype circuit with an input voltage of 24 V, an output voltage of 380 V, and an output rated power of 1 kW is implemented and tested to demonstrate the functionality of the proposed converter. Moreover, satisfying experimental results are obtained and discussed in this paper. The measured full-load efficiency is 95.2%, and the highest measured efficiency of the proposed converter is 96.3%.
Dead-Time for Zero-Voltage-Switching in Battery Chargers with the Phase-Shifted Full-Bridge Topology: Comprehensive Theoretical Analysis and Experimental Verification
Zhang, Taizhi ; Fu, Junyu ; Qian, Qinsong ; Sun, Weifeng ; Lu, Shengli ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 425~435
DOI : 10.6113/JPE.2016.16.2.425
This paper presents a comprehensive theoretical analysis and an accurate calculation method of the dead-time required to achieve zero-voltage-switching (ZVS) in a battery charger with the phase-shifted full-bridge (PSFB) topology. Compared to previous studies, this is the first time that the effects of nonlinear output filter inductance, varied Miller Plateau length, and blocking capacitors have been considered. It has been found that the output filter inductance and the Miller Plateau have a significant influence on the dead-time for ZVS when the load current varies a lot in battery charger applications. In addition, the blocking capacitor, which is widely used to prevent saturation, reduces the circulating current and consequently affects the setting of the dead-time. In consideration of these effects, accurate analytical equations of the dead-time range for ZVS are deduced. Experimental results from a 1.5kW PSFB battery charger prototype shows that, with the proposed analysis, an optimal dead-time can be selected to meet the specific requirements of a system while achieving ZVS over wide load range.
A Novel High Step-Up Converter with a Switched-Coupled-Inductor-Capacitor Structure for Sustainable Energy Systems
Liu, Hongchen ; Ai, Jian ; Li, Fei ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 436~446
DOI : 10.6113/JPE.2016.16.2.436
A novel step-up DC-DC converter with a switched-coupled-inductor-capacitor (SCIC) which successfully integrates three-winding coupled inductors and switched-capacitor techniques is proposed in this paper. The primary side of the coupled inductors for the SCIC is charged by the input source, and the capacitors are charged in parallel and discharged in series by the secondary windings of the coupled inductor to achieve a high step-up voltage gain with an appropriate duty ratio. In addition, the passive lossless clamped circuits recycle the leakage energy and reduce the voltage stress on the main switch effectively, and the reverse-recovery problem of the diodes is alleviated by the leakage inductor. Thus, the efficiency can be improved. The operating principle and steady-state analyses of the converter are discussed in detail. Finally, a prototype circuit at a 50 kHz switching frequency with a 20-V input voltage, a 200-V output voltage, and a 200-W output power is built in the laboratory to verify the performance of the proposed converter.
Three-Level SEPIC with Improved Efficiency and Balanced Capacitor Voltages
Choi, Woo-Young ; Lee, Seung-Jae ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 447~454
DOI : 10.6113/JPE.2016.16.2.447
A single-ended primary-inductor converter (SEPIC) features low input current ripple and output voltage up/down capability. However, the switching devices in a two-level SEPIC suffer from high voltage stresses and switching losses. To cope with this drawback, this study proposes a three-level SEPIC that uses a low voltage-rated switch and thus achieves better switching performance compared with the two-level SEPIC. The three-level SEPIC can reduce switch voltage stresses and switching losses. The converter operation and control method are described in this work. The experimental results for a 500 W prototype converter are also discussed. Experimental results show that unlike the two-level SEPIC, the three-level SEPIC achieves improved power efficiency with balanced capacitor voltages.
A Method to Compensate the Distorted Space Vectors in the Unbalanced Neutral Point Voltage of 3-level NPC PWM Inverters
Hyun, Seung-Wook ; Hong, Seok-Jin ; Lee, Jung-Hyo ; Lee, Chun-Bok ; Won, Chung-Yuen ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 455~463
DOI : 10.6113/JPE.2016.16.2.455
This paper proposes a compensation method to improve the distorted space vectors when a 3-level Neutral Point Clamped (NPC) inverter has an unbalanced neutral point voltage. Since both the neutral point voltage of the DC link and the space vector of a 3-level NPC inverter are closely related depending on the output load connecting state, a distorted space vector can occur when the neutral point voltage of a 3-level NPC inverter is unbalanced. The proposed method can improve the distorted space vectors by adjusting the injection time of the small and medium vectors and by modulating the amplitude of the carrier waveforms. In this paper, the proposed method is verified by both simulation and experimental results based on a 3-level NPC inverter.
Selective Harmonic Elimination in Multi-level Inverters with Series-Connected Transformers with Equal Power Ratings
Moussa, Mona Fouad ; Dessouky, Yasser Gaber ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 464~472
DOI : 10.6113/JPE.2016.16.2.464
This study applies the selective harmonic elimination (SHE) technique to design and operate a regulated AC/DC/AC power supply suitable for maritime military applications and underground trains. The input is a single 50/60 Hz AC voltage, and the output is a 400 Hz regulated voltage. The switching angles for a multi-level inverter and transformer turns ratio are determined to operate with special connected transformers with equal power ratings and produce an almost sinusoidal current. As a result of its capability of directly controlling harmonics, the SHE technique is applicable to apparatus with congenital immunity to specific harmonics, such as series-connected transformers, which are specially designed to equally share the total load power. In the present work, a single-phase 50/60 Hz input source is rectified via a semi-controlled bridge rectifier to control DC voltage levels and thereby regulate the output load voltage at a constant level. The DC-rectified voltage then supplies six single-phase quazi-square H-bridge inverters, each of which supplies the primary of a single-phase transformer. The secondaries of the six transformers are connected in series. Through off-line calculation, the switching angles of the six inverters and the turns ratios of the six transformers are designed to ensure equal power distribution for the transformers. The SHE technique is also employed to eliminate the higher-order harmonics of the output voltage. A digital implementation is carried out to determine the switching angles. Theoretical results are demonstrated, and a scaled-down experimental 600 VA prototype is built to verify the validity of the proposed system.
An Improved Phase-Shifted Carrier PWM for Modular Multilevel Converters with Redundancy Sub-Modules
Choi, Jong-Yun ; Han, Byung-Moon ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 473~479
DOI : 10.6113/JPE.2016.16.2.473
In this paper, the PSC PWM method is chosen as the optimal modulation method for a 20MW VSC HVDC, with consideration of the harmonic distortion of the output voltage, the switching frequency, and the control implementation difficulty. In addition, a new PSC PWM method is proposed in order to achieve an easy application and to solve the redundant control problems encountered in the previous PSC PWM method. To verify the proposed PSC PWM method, PSCAD/EMTDC simulations for an 11-level MMC RTDS HILS test and an 11-level MMC prototype converter test were performed. As can be seen from the results of these tests, the proposed PSC PWM method shows good results in an 11-level MMC with redundant sub-modules.
A Hybrid CBPWM Scheme for Single-Phase Three-Level Converters
Wang, Shunliang ; Song, Wensheng ; Feng, Xiaoyun ; Ding, Rongjun ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 480~489
DOI : 10.6113/JPE.2016.16.2.480
A novel hybrid carrier-based pulse width modulation (CBPWM) scheme that combines unipolar and dipolar modulations is proposed for single-phase three-level rectifiers, which are widely applied in railway traction drive systems. The proposed CBPWM method can satisfy the volt-second balancing principle in the complete modulation index region through overmodulation compensation. The modulation scheme features two modulation modes: unipolar and dipolar. The operation range limits of these modulation modes can be modified by changing the separation coefficient. In comparison with the traditional unipolar CBPWM, the proposed hybrid CBPWM scheme can provide advantageous features, such as lower high-order harmonic distortion of the line current and better utilization of switching frequency. The separation coefficient value is optimized to achieve the maximum utilization of these advantages. The experimental results verify the feasibility and effectiveness of the proposed hybrid CBPWM scheme.
An Improved SPWM Strategy to Reduce Switching in Cascaded Multilevel Inverters
Dong, Xiucheng ; Yu, Xiaomei ; Yuan, Zhiwen ; Xia, Yankun ; Li, Yu ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 490~497
DOI : 10.6113/JPE.2016.16.2.490
The analysis of the switch status of each unit module of a cascaded multi-level inverter reveals that the working condition of the switch of a chopper arm causes unnecessary switching under the conventional unipolar sinusoidal pulse width modulation (SPWM). With an increase in the number of cascaded multilevel inverters, the superposition of unnecessary switching gradually occurs. In this work, we propose an improved SPWM strategy to reduce switching in cascaded multilevel inverters. Specifically, we analyze the switch state of the switch tube of a chopper arm of an H-bridge unit. The redundant switch is then removed, thereby reducing the switching frequency. Unlike the conventional unipolar SPWM technique, the improved SPWM method greatly reduces switching without altering the output quality of inverters. The conventional unipolar SPWM technique and the proposed method are applied to a five-level inverter. Simulation results show the superiority of the proposed strategy. Finally, a prototype is built in the laboratory. Experimental results verify the correctness of the proposed modulation strategy.
PWM Control Techniques for Single-Phase Multilevel Inverter Based Controlled DC Cells
Sayed, Mahmoud A. ; Ahmed, Mahrous ; Elsheikh, Maha G. ; Orabi, Mohamed ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 498~511
DOI : 10.6113/JPE.2016.16.2.498
This paper presents a single-phase five-level inverter controlled by two novel pulse width modulation (PWM) switching techniques. The proposed PWM techniques are designed based on minimum switching power loss and minimum total harmonic distortion (THD). In a single-phase five-level inverter employing six switches, the first proposed PWM technique requires four switches to operate at switching frequency and two other switches to operate at line frequency. The second proposed PWM technique requires only two switches to operate at switching frequency and the rest of the switches to operate at line frequency. Compared with conventional PWM techniques for single-phase five-level inverters, the proposed PWM techniques offer high efficiency and low harmonic components in the output voltage. The validity of the proposed PWM switching techniques in controlling single-phase five-level inverters to regulate load voltage is verified experimentally using a 100 V, 500 W laboratory prototype controlled by dspace 1103.
An Improved Phase-Shifted Carrier Pulse Width Modulation Based on the Artificial Bee Colony Algorithm for Cascaded H-Bridge Multilevel Inverters
Cai, Xinjian ; Wu, Zhenxing ; Li, Quanfeng ; Wang, Shuxiu ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 512~521
DOI : 10.6113/JPE.2016.16.2.512
Cascaded H-bridge multilevel (CHBML) inverters usually include a large number of isolated dc-voltage sources. Some faults in the dc-voltage sources result in unequal cell dc voltages. Unfortunately, the conventional phase-shifted carrier (PSC) PWM method that is widely used for CHBML inverters cannot eliminate low frequency sideband harmonics when the cell dc voltages are not equal. This paper analyzes the principle of sideband harmonic elimination, and proposes an improved PSCPWM that can eliminate low frequency sideband harmonics under the condition of unequal dc voltages. In order to calculate the carrier phases, it is necessary to solve transcendental equations for low frequency sideband harmonic elimination. Therefore, an approach based on the artificial bee colony (ABC) algorithm is presented in this paper. The proposed PSCPWM method enhances the reliability of CHBML inverters. The proposed PSCPWM is not limited to CHBML inverters. It can also be applied to other types of multilevel inverters. Simulation and experimental result obtained from a prototype CHBML inverter verify the theoretical analysis and the achievements made in this paper.
A New Scheme for Nearest Level Control with Average Switching Frequency Reduction for Modular Multilevel Converters
Park, Yong-Hee ; Kim, Do-Hyun ; Kim, Jae-Hyuk ; Han, Byung-Moon ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 522~531
DOI : 10.6113/JPE.2016.16.2.522
This paper proposes a new NLC (Nearest Level Control) scheme for MMCs (Modular Multilevel Converters), which offers voltage ripple reductions in the DC capacitor of the SM (Sub-Module), the output voltage harmonics, and the switching losses. The feasibility of the proposed NLC was verified through computer simulations. Based on these simulation results, a hardware prototype of a 10kVA, DC-1000V MMC was manufactured in the lab. Experiments were conducted to verify the feasibility of the proposed NLC in an actual hardware environment. The experimental results were consistent with the results obtained from the computer simulations.
A Single-Phase Cell-Based Asymmetrical Cascaded Multilevel Inverter
Singh, Varsha ; Pattnaik, Swapnajit ; Gupta, Shubhrata ; Santosh, Bokam ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 532~541
DOI : 10.6113/JPE.2016.16.2.532
A single-phase asymmetrical cascaded multilevel inverter is introduced with the goal of increasing power quality with the reduction of power in insulated-gate bipolar transistor (IGBT) switches. In the present work, the proposed inverter topology is analyzed and generalized with respect to different proposed algorithms for choosing different voltage source values. To prove the advantages of the proposed inverter, a case study involving a 17-level inverter is conducted. The simulation and experimental results with reduced THD are also presented and compared with the MATLAB/SIMULINK simulation results. Finally, the proposed topology is compared with different multilevel inverter topologies available in the literature in terms of the number of IGBT switches required with respect to the number of levels generated in the output of inverter topologies.
An Improved Central 60° Synchronous Modulation for High Transient Performance with PMSM Stator Flux Control Used in Urban Rail Transit Systems
Fang, Xiaochun ; Lin, Fei ; Yang, Zhongping ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 542~552
DOI : 10.6113/JPE.2016.16.2.542
Central 60° synchronous modulation is an easy pulse-width modulation (PWM) method to implement for the traction inverters of urban rail trains at a very low switching frequency. Unfortunately, its switching patterns are determined by a Fourier analysis of assumed steady-state voltages. As a result, its transient responses are not very good with over-currents and high instantaneous torque pulses. In the proposed solution, the switching patterns of the conventional central 60° modulation are modified according to the dynamic error between the target and actual stator flux. Then, the specific trajectory of the stator flux and current vector can be guaranteed, which leads to better system transients. In addition, stator flux control is introduced to get smooth mode switching between the central 60° modulation and the other PWMs in this paper. A detailed flow chart of the control signal transmission is given. The target flux is obtained by an integral of the target voltage. The actual PMSM flux is estimated by a minimum order flux state observer based on the extended flux model. Based on a two-level inverter model, improved rules in the α-β stationary coordinate system and equations of the switching patterns amendment are proposed. The proposed method is verified by simulation and experimental results.
Design and Implementation of an FPGA-based Real-time Simulator for a Dual Three-Phase Induction Motor Drive
Gregor, Raul ; Valenzano, Guido ; Rodas, Jorge ; Rodriguez-Pineiro, Jose ; Gregor, Derlis ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 553~563
DOI : 10.6113/JPE.2016.16.2.553
This paper presents a digital hardware implementation of a real-time simulator for a multiphase drive using a field-programmable gate array (FPGA) device. The simulator was developed with a modular and hierarchical design using very high-speed integrated circuit hardware description language (VHDL). Hence, this simulator is flexible and portable. A state-space representation model suitable for FPGA implementations was proposed for a dual three-phase induction machine (DTPIM). The simulator also models a two-level 12-pulse insulated-gate bipolar transistor (IGBT)-based voltage-source converter (VSC), a pulse-width modulation scheme, and a measurement system. Real-time simulation outputs (stator currents and rotor speed) were validated under steady-state and transient conditions using as reference an experimental test bench based on a DTPIM with 15 kW-rated power. The accuracy of the proposed digital hardware implementation was evaluated according to the simulation and experimental results. Finally, statistical performance parameters were provided to analyze the efficiency of the proposed DTPIM hardware implementation method.
Analysis and Implementation of ANFIS-based Rotor Position Controller for BLDC Motors
Navaneethakkannan, C. ; Sudha, M. ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 564~571
DOI : 10.6113/JPE.2016.16.2.564
This study proposes an adaptive neuro-fuzzy inference system (ANFIS)-based rotor position controller for brushless direct current (BLDC) motors to improve the control performance of the drive under transient and steady-state conditions. The dynamic response of a BLDC motor to the proposed ANFIS controller is considered as standard reference input. The effectiveness of the proposed controller is compared with that of the proportional integral derivative (PID) controller and fuzzy PID controller. The proposed controller solves the problem of nonlinearities and uncertainties caused by the reference input changes of BLDC motors and guarantees a fast and accurate dynamic response with an outstanding steady-state performance. Furthermore, the ANFIS controller provides low torque ripples and high starting torque. The detailed study includes a MATLAB-based simulation and an experimental prototype to illustrate the feasibility of the proposed topology.
A DTC Stator Flux Algorithm for the Performance Improvement of Induction Traction Motors
Van-Tien, Pham ; Zheng, Trillion Q. ; Yang, Zhong-ping ; Lin, Fei ; Do, Viet-dung ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 572~583
DOI : 10.6113/JPE.2016.16.2.572
In view of the speed control characteristics of induction traction motors and the problems of direct torque control (DTC) algorithms in current applications, this paper presents a DTC algorithm characterized by a symmetrical polygon flux control and a closed loop power control in the constant-torque base speed region and constant-power field-weakening region of induction traction motors. This algorithm only needs to add a stator flux control algorithm to the traditional DTC structures. This has the benefit of simplicity, while maintaining the features of traditional algorithms such as a rapid dynamic response, uncomplicated control circuit, reduced dependence on motor parameters, etc. In addition, it obtains a smoother flux trajectory that is conducive to improvement of the harmonic elimination capability, the switching frequency utilization as well as the torque and power performance in the field-weakening region. The effectiveness and feasibility of this DTC algorithm are demonstrated by both theoretical analysis and experimental results.
Transient Performance Improvement in the Boundary Control of Boost Converters using Synthetic Optimized Trajectory
Feng, Gaohui ; Yuan, Liqiang ; Zhao, Zhengming ; Ge, Junjie ; Ye, Xiuxi ; Lu, Ting ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 584~597
DOI : 10.6113/JPE.2016.16.2.584
This paper focuses on an improvement in the transient performance of Boost converters when the load changes abruptly. This is achieved on the basis of the nature trajectory in Boost converters. Three key aspects of the transient performance are analyzed including the storage energy change law in the inductors and capacitors of converters during the transient process, the ideal minimum voltage deviation in the transient process, and the minimum voltage deviation control trajectory. The changing relationship curve between the voltage deviation and the recovery time is depicted through analysis and simulations when the load suddenly increases. In addition, the relationship curve between the current fluctuation and the recovery time is obtained when the load suddenly decreases. Considering the aspects of an increasing and decreasing load, this paper proposes the transient performance synthetic optimized trajectory and control laws. Through simulation and experimental results, the transient performances are compared with the other typical three control methods, and the ability of proposed synthetic trajectory and control law to achieve optimal transient performance is verified.
A Backstepping Control of LSM Drive Systems Using Adaptive Modified Recurrent Laguerre OPNNUO
Lin, Chih-Hong ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 598~609
DOI : 10.6113/JPE.2016.16.2.598
The good control performance of permanent magnet linear synchronous motor (LSM) drive systems is difficult to achieve using linear controllers because of uncertainty effects, such as fictitious forces. A backstepping control system using adaptive modified recurrent Laguerre orthogonal polynomial neural network uncertainty observer (OPNNUO) is proposed to increase the robustness of LSM drive systems. First, a field-oriented mechanism is applied to formulate a dynamic equation for an LSM drive system. Second, a backstepping approach is proposed to control the motion of the LSM drive system. With the proposed backstepping control system, the mover position of the LSM drive achieves good transient control performance and robustness. As the LSM drive system is prone to nonlinear and time-varying uncertainties, an adaptive modified recurrent Laguerre OPNNUO is proposed to estimate lumped uncertainties and thereby enhance the robustness of the LSM drive system. The on-line parameter training methodology of the modified recurrent Laguerre OPNN is based on the Lyapunov stability theorem. Furthermore, two optimal learning rates of the modified recurrent Laguerre OPNN are derived to accelerate parameter convergence. Finally, the effectiveness of the proposed control system is verified by experimental results.
An Optimized PI Controller Design for Three Phase PFC Converters Based on Multi-Objective Chaotic Particle Swarm Optimization
Guo, Xin ; Ren, Hai-Peng ; Liu, Ding ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 610~620
DOI : 10.6113/JPE.2016.16.2.610
The compound active clamp zero voltage soft switching (CACZVS) three-phase power factor correction (PFC) converter has many advantages, such as high efficiency, high power factor, bi-directional energy flow, and soft switching of all the switches. Triple closed-loop PI controllers are used for the three-phase power factor correction converter. The control objectives of the converter include a fast transient response, high accuracy, and unity power factor. There are six parameters of the controllers that need to be tuned in order to obtain multi-objective optimization. However, six of the parameters are mutually dependent for the objectives. This is beyond the scope of the traditional experience based PI parameters tuning method. In this paper, an improved chaotic particle swarm optimization (CPSO) method has been proposed to optimize the controller parameters. In the proposed method, multi-dimensional chaotic sequences generated by spatiotemporal chaos map are used as initial particles to get a better initial distribution and to avoid local minimums. Pareto optimal solutions are also used to avoid the weight selection difficulty of the multi-objectives. Simulation and experiment results show the effectiveness and superiority of the proposed method.
A Performance Comparison of the Current Feedback Schemes with a New Single Current Sensor Technique for Single-Phase Full-Bridge Inverters
Choe, Jung-Muk ; Lee, Young-Jin ; Cho, Younghoon ; Choe, Gyu-Ha ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 621~630
DOI : 10.6113/JPE.2016.16.2.621
In this paper, a single current sensor technique (SCST) is proposed for single-phase full-bridge inverters. The proposed SCST measures the currents of multiple branches at the same time, and reconstructs the average inductor, capacitor, and load current in a single switching cycle. Since all of the branches' current in the LC filter and the load are obtained using the SCST, both the inductor and the capacitor current feedback schemes can be selectively applied while taking advantages of each other. This paper also analyzes both of the current feedback schemes from the view point of the closed-loop output impedance. The proposed SCST and the analysis in this paper are verified through experiments on a 3kVA single-phase uninterruptible power supply (UPS).
The Influence of Changing PV Array Interconnections under a Non-uniform Irradiance
Ding, Kun ; Feng, Li ; Qin, Si-Yu ; Mao, Jing ; Zhang, Jing-Wei ; Wang, Xiang ; Peng, Tao ; Zhai, Quan-Xin ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 631~642
DOI : 10.6113/JPE.2016.16.2.631
Usually, the output characteristics of a photovoltaic (PV) array are significantly affected by non-uniform irradiance which is caused by ambient obstacles, clouds, orientations, tilts, etc. Some local maximum power points (LMPP) in the current-voltage (I-V) curves of a PV array can result in power losses of the array. However, the output power at the global maximum power point (GMPP) is different in different interconnection schemes in a PV array. Therefore, based on the theoretical analysis and mathematical derivation of different topological structures of a PV array, this paper investigated the output characteristics of dual series PV arrays with different interconnections. The proposed mathematical models were also validated by experimental results. Finally, this paper also concluded that in terms of performance, the total cross tied (TCT) interconnection was not always the optimal structure, especially in a dual series PV array. When one of the PV modules was severely mismatched, the TCT worked worse than the series parallel (SP) structure. This research can provide guidance for switching the interconnection to gain the greatest energy yield in a changeable- structure PV system.
Estimating the State-of-Charge of Lithium-Ion Batteries Using an H-Infinity Observer with Consideration of the Hysteresis Characteristic
Xie, Jiale ; Ma, Jiachen ; Sun, Yude ; Li, Zonglin ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 643~653
DOI : 10.6113/JPE.2016.16.2.643
The conventional methods used to evaluate battery state-of-charge (SOC) cannot accommodate the chemistry nonlinearities, measurement inaccuracies and parameter perturbations involved in estimation systems. In this paper, an impedance-based equivalent circuit model has been constructed with respect to a LiFePO
battery by approximating the electrochemical impedance spectrum (EIS) with RC circuits. The efficiencies of approximating the EIS with RC networks in different series-parallel forms are first discussed. Additionally, the typical hysteresis characteristic is modeled through an empirical approach. Subsequently, a methodology incorporating an H-infinity observer designated for open-circuit voltage (OCV) observation and a hysteresis model developed for OCV-SOC mapping is proposed. Thereafter, evaluation experiments under FUDS and UDDS test cycles are undertaken with varying temperatures and different current-sense bias. Experimental comparisons, in comparison with the EKF based method, indicate that the proposed SOC estimator is more effective and robust. Moreover, test results on a group of Li-ion batteries, from different manufacturers and of different chemistries, show that the proposed method has high generalization capability for all the three types of Li-ion batteries.
A Novel Photovoltaic Power Harvesting System Using a Transformerless H6 Single-Phase Inverter with Improved Grid Current Quality
Radhika, A. ; Shunmugalatha, A. ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 654~665
DOI : 10.6113/JPE.2016.16.2.654
The pumping of electric power from photovoltaic (PV) farms is normally carried out using transformers, which require heavy mounting structures and are thus costly, less efficient, and bulky. Therefore, transformerless schemes are developed for the injection of power into the grid. Compared with the H4 inverter topology, the H6 topology is a better choice for pumping PV power into the grid because of the reduced common mode current. This paper presents how the perturb and observe (P&O) algorithm for maximum power point tracking (MPPT) can be implemented in the H6 inverter topology along with the improved sinusoidal current injected to the grid at unity power factor with the average current mode control technique. On the basis of the P&O MPPT algorithm, a power reference for the present insolation level is first calculated. Maintaining this power reference and referring to the AC sine wave of bus bars, a sinusoidal current at unity power factor is injected to the grid. The proportional integral (PI) controller and fuzzy logic controller (FLC) are designed and implemented. The FLC outperforms the PI controller in terms of conversion efficiency and injected power quality. A simulation in the MATLAB/SIMULINK environment is carried out. An experimental prototype is built to validate the proposed idea. The dynamic and steady-state performances of the FLC controller are found to be better than those of the PI controller. The results are presented in this paper.
The Design and Construction of a High Efficiency Satellite Electrical Power Supply System
Mousavi, Navid ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 666~674
DOI : 10.6113/JPE.2016.16.2.666
In this paper, a high efficiency satellite electrical power supply system is proposed. The increased efficiency of the power supply system allows for downscaling of the solar array and battery weight, which are among the most important satellite design considerations. The satellite power supply system comprises two units, namely a generation unit and a storage unit. To increase the efficiency of the solar array, a maximum power point tracker (MPPT) is used in the power generation unit. In order to improve the MPPT performance, a novel algorithm is proposed on the basis of the hill climbing method. This method can track the main peak of the array power curve in satellites with long duration missions under unpredicted circumstances such as a part of the array being damaged or the presence of a shadow. A lithium-ion battery is utilized in the storage unit. An algorithm for calculating the optimal rate of battery charging is proposed where the battery is charged with the maximum possible efficiency considering the situation of the satellite. The proposed system is designed and manufactured. In addition, it is compared to the conventional power supply systems in similar satellites. Results show a 12% increase in the overall efficiency of the power supply system when compared to the conventional method.
Sliding Mode Control of a New Wind-Based Isolated Three-Phase Induction Generator System with Constant Frequency and Adjustable Output Voltage
Moradian, Mohammadreza ; Soltani, Jafar ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 675~684
DOI : 10.6113/JPE.2016.16.2.675
This paper presents a new stand-alone wind-based induction generator system with constant frequency and adjustable output voltage. The proposed generator consists of a six-phase cage-rotor induction machine with two separate three-phase balanced stator windings and a three-phase space vector pulse width modulation inverter that operates as a static synchronous compensator (STATCOM). The first stator winding is fed by the STATCOM and used to excite the machine while the second stator winding is connected to the generator external load. The main frequency of the STATCOM is determined to be constant and equal to the load-requested frequency. The generator output frequency is independent of the load power demand and its prime mover speed because the frequency of the induced emf in the second stator winding is the same as this constant frequency. A sliding mode control (SMC) is developed to regulate the generator output voltage. A second SMC is used to force the zero active power exchanged between the machine and the STATCOM. Some simulation and experimental results are presented to prove the validity and effectiveness of the proposed generator system.
A Reliability Evaluation Model for the Power Devices Used in Power Converter Systems Considering the Effect of the Different Time Scales of the Wind Speed Profile
Ji, Haiting ; Li, Hui ; Li, Yang ; Yang, Li ; Lei, Guoping ; Xiao, Hongwei ; Zhao, Jie ; Shi, Lefeng ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 685~694
DOI : 10.6113/JPE.2016.16.2.685
This paper presents a reliability assessment model for the power semiconductors used in wind turbine power converters. In this study, the thermal loadings at different timescales of wind speed are considered. First, in order to address the influence of long-term thermal cycling caused by variations in wind speed, the power converter operation state is partitioned into different phases in terms of average wind speed and wind turbulence. Therefore, the contributions can be considered separately. Then, in regards to the reliability assessment caused by short-term thermal cycling, the wind profile is converted to a wind speed distribution, and the contribution of different wind speeds to the final failure rate is accumulated. Finally, the reliability of an actual power converter semiconductor for a 2.5 MW wind turbine is assessed, and the failure rates induced by different timescale thermal behavior patterns are compared. The effects of various parameters such as cut-in, rated, cut-out wind speed on the failure rate of power devices are also analyzed based on the proposed model.
Design of a Fuel Cell Power Conditioning System for Online Diagnosis and Load Leveling
Nguyen, Thanh-Tuan ; Doan, Van-Tuan ; Choi, Woojin ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 695~703
DOI : 10.6113/JPE.2016.16.2.695
A fuel cell power conditioning system for online diagnosis and load leveling under the condition of varying load is developed in this study. The proposed system comprises a unidirectional boost converter and a bidirectional buck-boost converter with a battery. The system operates in two different modes. In normal mode, the bidirectional converter is utilized for load leveling; in diagnostic mode, it is utilized to control load voltage while the boost converter generates perturbation current to implement the online diagnosis function through in-situ electrochemical impedance spectroscopy (EIS). The proposed method can perform EIS for a fuel cell under varying-load conditions with no influence on the load. The validity and feasibility of the proposed system are verified by experiments, and the design procedure of the proposed system is detailed.
Single-Phase Inverter for Grid-Connected and Intentional Islanding Operations in Electric Utility Systems
Lidozzi, Alessandro ; Lo Calzo, Giovanni ; Solero, Luca ; Crescimbini, Fabio ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 704~716
DOI : 10.6113/JPE.2016.16.2.704
Small distributed generation units are usually connected to the main electric grid through single-phase voltage source inverters. Grid operating conditions such as voltage and frequency are not constant and can fluctuate within the range values established by international standards. Furthermore, the requirements in terms of power factor correction, total harmonic distortion, and reliability are getting tighter day by day. As a result, the implementation of reliable and efficient control algorithms, which are able to adjust their control parameters in response to changeable grid operating conditions, is essential. This paper investigates the configuration topology and control algorithm of a single-phase inverter with the purpose of achieving high performance in terms of efficiency as well as total harmonic distortion of the output current. Accordingly, a Second Order Generalized Integrator with a suitable Phase Locked Loop (SOGI-PLL) is the basis of the proposed current and voltage regulation. Some practical issues related to the control algorithm are addressed, and a solution for the control architecture is proposed, based on resonant controllers that are continuously tuned on the basis of the actual grid frequency. Further, intentional islanding operation is investigated and a possible procedure for switching from grid-tied to islanding operation and vice-versa is proposed.
A Quantitative Evaluation and Comparison of Harmonic Elimination Algorithms Based on Moving Average Filter and Delayed Signal Cancellation in Phase Synchronization Applications
Xiong, Liansong ; Zhuo, Fang ; Wang, Feng ; Liu, Xiaokang ; Zhu, Minghua ; Yi, Hao ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 717~730
DOI : 10.6113/JPE.2016.16.2.717
The harmonic components of grid voltage result in oscillations of the calculated phase obtained via phase synchronization. This affects the security and stability of grid-connected converters. Moving average filter, delayed signal cancellation and their related harmonic elimination algorithms are major methods for such issues. However, all of the existing methods have their limitations in dealing with multiple harmonics issues. Furthermore, few studies have focused on a comparison and evaluation of these algorithms to achieve optimal algorithm selections in specific applications. In this paper, these algorithms are quantitatively analyzed based on the derived mathematical models. Moreover, an enhanced moving average filter and enhanced delayed signal cancellation algorithms, which are applicable for eliminating a group of selective harmonics with only one calculation block, are proposed. On this basis, both a comprehensive comparison and a quantitative evaluation of all of the aforementioned algorithms are made from several aspects, including response speed, required data storage size, sensitivity to sampling frequency, and elimination of random noise and harmonics. With the conclusions derived in this paper, better overall performance in terms of harmonic elimination can be achieved. In addition, experimental results under different conditions demonstrate the validity of this study.
Evaluation and Comparison of the Low-Frequency Oscillation Damping Methods for the Droop-Controlled Inverters in Distributed Generation Systems
Tao, Yong ; Deng, Yan ; Li, Guangdi ; Chen, Guipeng ; He, Xiangning ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 731~747
DOI : 10.6113/JPE.2016.16.2.731
The droop-based control strategy is widely applied in the interfacing inverters for distributed generation. This can be a problem since low-frequency stability issues may be encountered in droop-based microgrid. The objective of this paper is to classify, evaluate and compare various low-frequency damping methods. First, low-frequency stability problems are analyzed and an equivalent model of a droop-controlled inverter is investigated to classify the damping methods into the source-type damping strategies and the impedance-type damping strategies. Moreover, the lead-lag compensation network insertion control is proposed as a beneficial part of the source-type damping strategies. Then, the advantages and disadvantages of the different types of damping methods are theoretically evaluated and experimentally tested. Furthermore, the damping methods are comprehensively compared to illustrate the application field of each method. Finally, the synthesis of different damping methods to enhance the low-frequency stability is discussed and experimental validation is presented.
A Control and Protection Model for the Distributed Generation and Energy Storage Systems in Microgrids
Ballal, Makarand Sudhakar ; Bhadane, Kishor V. ; Moharil, Ravindra M. ; Suryawanshi, Hiralal M. ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 748~759
DOI : 10.6113/JPE.2016.16.2.748
The microgrid concept is a promising approach for injecting clean, renewable, and reliable electricity into power systems. It can operate in both the grid-connected and the islanding mode. This paper addresses the two main challenges associated with the operation of a microgrid i.e. control and protection. A control strategy for inverter based distributed generation (DG) and an energy storage system (ESS) are proposed to control both the voltage and frequency during islanding operation. The protection scheme is proposed to protect the lines, DG and ESS. Further, the control scheme and the protection scheme are coordinated to avoid nuisance tripping of the DG, ESS and loads. The feasibility of the proposed method is verified by simulation and experimental results.
A New Islanding Detection Method Based on Feature Recognition Technology
Zheng, Xinxin ; Xiao, Lan ; Qin, Wenwen ; Zhang, Qing ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 760~768
DOI : 10.6113/JPE.2016.16.2.760
Three-phase grid-connected inverters are widely applied in the fields of new energy power generation, electric vehicles and so on. Islanding detection is necessary to ensure the stability and safety of such systems. In this paper, feature recognition technology is applied and a novel islanding detection method is proposed. It can identify the features of inverter systems. The theoretical values of these features are defined as codebooks. The difference between the actual value of a feature and the codebook is defined as the quantizing distortion. When islanding happens, the sum of the quantizing distortions exceeds the threshold value. Thus, islanding can be detected. The non-detection zone can be avoided by choosing reasonable features. To accelerate the speed of detection and to avoid miscalculation, an active islanding detection method based on feature recognition technology is given. Compared to the active frequency or phase drift methods, the proposed active method can reduce the distortion of grid-current when the inverter works normally. The principles of the islanding detection method based on the feature recognition technology and the improved active method are both analyzed in detail. An 18 kVA DSP-based three-phase inverter with the SVPWM control strategy has been established and tested. Simulation and experimental results verify the theoretical analysis.
Current Sharing Control Strategy for IGBTs Connected in Parallel
Perez-Delgado, Raul ; Velasco-Quesada, Guillermo ; Roman-Lumbreras, Manuel ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 769~777
DOI : 10.6113/JPE.2016.16.2.769
This work focuses on current sharing between punch-through insulated gate bipolar transistors (IGBTs) connected in parallel and evaluates the mechanisms that allow overall current balancing. Two different control strategies are presented. These strategies are based on the modification of transistor gate-emitter control voltage V
by using an active gate driver circuit. The first strategy relies on the calculation of the average value of the current flowing through all parallel-connected IGBTs. The second strategy is proposed by the authors on the basis of a current cross reference control scheme. Finally, the simulation and experimental results of the application of the two current sharing control algorithms are presented.
An Excess Carrier Lifetime Extraction Method for Physics-based IGBT Models
Fu, Guicui ; Xue, Peng ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 778~785
DOI : 10.6113/JPE.2016.16.2.778
An excess carrier lifetime extraction method is derived for physics-based insulated gate bipolar transistor (IGBT) models with consideration of the latest development in IGBT modeling. On the basis of the 2D mixed-mode Sentaurus simulation, the clamp turn-off test is simulated to obtain the tail current. The proposed excess carrier lifetime extraction method is then performed using the simulated data. The comparison between the extracted results and actual lifetime directly obtained from the numerical device model precisely demonstrates the accuracy of the proposed method.
Development of a Novel 30 kV Solid-state Switch for Damped Oscillating Voltage Testing System
Hou, Zhe ; Li, Hongjie ; Li, Jing ; Ji, Shengchang ; Huang, Chenxi ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 786~797
DOI : 10.6113/JPE.2016.16.2.786
This paper describes the design and development of a novel semiconductor-based solid-state switch for damped oscillating voltage test system. The proposed switch is configured as two identical series-connected switch stacks, each of which comprising 10 series-connected IGBT function units. Each unit consists of one IGBT, a gate driver, and an auxiliary voltage sharing circuit. A single switch stack can block 20 kV-rated high voltage, and two stacks in series are proven applicable to 30 kV-rated high voltage. The turn-on speed of the switch is approximately 250 ns. A flyback topology-based power supply system with a front-end power factor correction is built for the drive circuit by loosely inductively coupling each unit with a ferrite core to the primary side of a power generator to obtain the advantages of galvanic isolation and compact size. After the simulation, measurement, and estimation of the parasitic effect on the gate driver, a prototype is assembled and tested under different operating regimes. Experimental results are presented to demonstrate the performance of the developed prototype.
A Control Method for Power-Assist Devices using a BLDC Motor for Manual Wheelchairs
Kim, Dong-Youn ; Kim, Yong-Hyu ; Kim, Kwang-Sik ; Kim, Jang-Mok ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 798~804
DOI : 10.6113/JPE.2016.16.2.798
This paper proposes a new operation and control strategy for Power-Assisted Wheelchairs (PAW) using one brushless DC (BLDC) motor. The conventional electrical wheelchairs are too heavy and large for one person to move because they have two electric motor wheels. On the other hand, the proposed PAW system has a small volume and is easy to move due to the presence of a single wheel motor. Unlike the conventional electric wheelchairs, this structure for a PAW does not have a control joystick to reduce its weight and volume. To control the wheelchair without a joystick, a special control system and algorithm are needed for proper operation of the wheelchair. In the proposed PAW system uses only one sensor to detect the acceleration and direction of PAW's movement. By using this sensor, speed control can be achieved. With a speed control system, there are three kinds of operations that can be done on the speed of a PAW: the increment of PAW speed by summing external force, the decrement of PAW speed by subtracting external force, and emergency breaking by evaluating the time duration of external force. The validity of the proposed algorithm is verified through experimental results.
A Shared Channel Design for the Power and Signal Transfers of Electric-field Coupled Power Transfer Systems
Su, Yu-Gang ; Zhou, Wei ; Hu, Aiguo Patrick ; Tang, Chun-Sen ; Hua, Rong ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 805~814
DOI : 10.6113/JPE.2016.16.2.805
Electric-field coupled power transfer (ECPT) systems have been proposed as an alternative wireless power transfer (WPT) technology in recent years. With the use of capacitive plates as a coupling structure, ECPT systems have many advantages such as design flexibility, reduced volume of the coupling structure and metal penetration ability. In addition, wireless communications are effective solutions to improve the safety and controllability of ECPT systems. This paper proposes a power and signal shared channel for electric-field coupled power transfer systems. The shared channel includes two similar electrical circuits with a band pass filter and a signal detection resistor in each. This is designed based on the traditional current-fed push-pull topology. An analysis of the mutual interference between the power and signal transmission, the channel power and signal attenuations, and the dynamic characteristic of the signal channel are conducted to determine the values for the electrical components of the proposed shared channel. Experimental results show that the designed channel can transfer over 100W of output power and data with a data rate from 300bps to 120 kbps.
An Estimation Method for the Efficiency of Light-Emitting Diode (LED) Devices
Tao, Xuehui ; Yang, Bin ;
Journal of Power Electronics, volume 16, issue 2, 2016, Pages 815~822
DOI : 10.6113/JPE.2016.16.2.815
The efficiency of light-emitting diode (LED) devices is a significant factor that reflects the capability of these devices to convert electrical power into optical power. In this study, a method for estimating the efficiency of LED devices is proposed. An efficiency model and a heat power model are established as convenient tools for LED performance evaluation. Such models can aid in the design of LED drivers and in the reliability evaluation of LED devices. The proposed estimation method for the efficiency and heat power of LED devices is verified by experimentally testing two types of commercial LED devices.