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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Power Electronics
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Journal DOI :
The Korean Institute of Power Electronics
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Volume & Issues
Volume 15, Issue 6 - Nov 2015
Volume 15, Issue 5 - Sep 2015
Volume 15, Issue 4 - Jul 2015
Volume 15, Issue 3 - May 2015
Volume 15, Issue 2 - Mar 2015
Volume 15, Issue 1 - Jan 2015
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Evaluation and Design Tools for the Reliability of Wind Power Converter System
Ma, Ke ; Zhou, Dao ; Blaabjerg, Frede ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1149~1157
DOI : 10.6113/JPE.2015.15.5.1149
As a key part in the wind turbine system, the power electronic converter is proven to have high failure rates. At the same time, the failure of the wind power converter is becoming more unacceptable because of the quick growth in capacity, remote locations to reach, and strong impact to the power grid. As a result, the correct assessment of reliable performance for power electronics is a crucial and emerging need; the assessment is essential for design improvement, as well as for the extension of converter lifetime and reduction of energy cost. Unfortunately, there still exists a lack of suitable physic-of-failure based evaluation tools for a reliability assessment in power electronics. In this paper, an advanced tool structure which can acquire various reliability metrics of wind power converter is proposed. The tool is based on failure mechanisms in critical components of the system and mission profiles in wind turbines. Potential methodologies, challenges, and technology trends involved in this tool structure are also discussed. Finally, a simplified version of the tool is demonstrated on a wind power converter based on Double Fed Induction Generator system. With the proposed tool structure, more detailed information of reliability performances in a wind power converter can be obtained before the converter can actually fail in the field and many potential research topics can also be initiated.
A Hybrid PWM-Resonant DC-DC Converter for Electric Vehicle Battery Charger Applications
Lee, Il-Oun ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1158~1167
DOI : 10.6113/JPE.2015.15.5.1158
In this paper, a new hybrid DC-DC converter is proposed for electric vehicle 3.3 kW on-board battery charger applications, which can be modulated in a phase-shift manner under a fixed frequency or frequency variation. By integrating a half-bridge (HB) LLC series resonant converter (SRC) into the conventional phase-shift full-bridge (PSFB) converter with a full-bridge rectifier, the proposed converter has many advantages such as a full soft-switching range without duty-cycle loss, zero-current-switching operation of the rectifier diodes, minimized circulating current, reduced filter inductor size, and better utilization of transformers than other hybrid dc-dc converters. The feasibility of the proposed converter has been verified by experimental results under an output voltage range of 250-420V dc at 3.3 kW.
Scheme to Improve the Line Current Distortion of PFC Using a Predictive Control Algorithm
Kim, Dae Joong ; Park, Jin-Hyuk ; Lee, Kyo-Beum ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1168~1177
DOI : 10.6113/JPE.2015.15.5.1168
This paper presents a scheme to improve the line current distortion of power factor corrector (PFC) topology at the zero crossing point using a predictive control algorithm in both the continuous conduction mode (CCM) and discontinuous conduction mode (DCM). The line current in single-phase PFC topology is distorted at the zero crossing point of the input AC voltage because of the characteristic of the general proportional integral (PI) current controller. This distortion degrades the line current quality, such as the total harmonic distortion (THD) and the power factor (PF). Given the optimal duty cycle calculated by estimating the next state current in both the CCM and DCM, the proposed predictive control algorithm has a fast dynamic response and accuracy unlike the conventional PI current control method. These advantages of the proposed algorithm lower the line current distortion of PFC topology. The proposed method is verified through PSIM simulations and experimental results with 1.5 kW bridgeless PFC (BLPFC) topology.
Synthesis and Implementation of a Multi-Port DC/DC Converter for Hybrid Electric Vehicles
Santhosh, T. K. ; Natarajan, K. ; Govindaraju, C. ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1178~1189
DOI : 10.6113/JPE.2015.15.5.1178
A non-isolated Multiple Input Converter (MIC) with an input port, two storage ports and a load port is proposed. The synthesis of the proposed four port converter with its switch realization is presented. A steady state analysis of each operating mode with a small-signal model is derived, and a stability analysis is done. A mode selection controller is proposed to automatically choose a specific operating mode based on the voltage levels of the different source and storage units. In addition, a voltage control loop is used to regulate the output voltage. A 200W prototype is built with a TMS320F28027 DSP controller to test the feasibility of the operating modes. Simulation and experimental results show the ability of the proposed converter to handle multiple inputs either individually or simultaneously.
A ZVS Resonant Converter with Balanced Flying Capacitors
Lin, Bor-Ren ; Chen, Zih-Yong ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1190~1199
DOI : 10.6113/JPE.2015.15.5.1190
This paper presents a new resonant converter to achieve the soft switching of power devices. Two full-bridge converters are connected in series to clamp the voltage stress of power switches at V
/2. Thus, power MOSFETs with a 500V voltage rating can be used for 800V input voltage applications. Two flying capacitors are connected on the AC side of the two full-bridge converters to automatically balance the two split input capacitor voltages in every switching cycle. Two resonant tanks are used in the proposed converter to share the load current and to reduce the current stress of the passive and active components. If the switching frequency is less than the series resonant frequency of the resonant tanks, the power MOSFETs can be turned on under zero voltage switching, and the rectifier diodes can be turned off under zero current switching. The switching losses on the power MOSFETs are reduced and the reverse recovery loss is improved. Experiments with a 1.5kW prototype are provided to demonstrate the performance of the proposed converter.
Actively Clamped Two-Switch Flyback Converter with High Efficiency
Yang, Min-Kwon ; Choi, Woo-Young ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1200~1206
DOI : 10.6113/JPE.2015.15.5.1200
This paper proposes an actively clamped two-switch flyback converter. Compared to the conventional two-switch flyback converter, the proposed two-switch flyback converter operates with a wide duty cycle range. By using an active-clamp circuit, the proposed converter achieves zero-voltage switching for all of the power switches. Zero-current switching of an output diode is also achieved. Thus, compared with the conventional converter, the proposed converter realizes a higher efficiency with an extended duty cycle. The performance of the proposed converter is verified by the experimental results with use of a 1.0 kW prototype circuit.
A New DPWM Method to Suppress the Low Frequency Oscillation of the Neutral-Point Voltage for NPC Three-Level Inverters
Lyu, Jianguo ; Hu, Wenbin ; Wu, Fuyun ; Yao, Kai ; Wu, Junji ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1207~1216
DOI : 10.6113/JPE.2015.15.5.1207
In order to suppress the low frequency oscillation of the neutral-point voltage for three-level inverters, this paper proposes a new discontinuous pulse width modulation (DPWM) control method. The conventional sinusoidal pulse width modulation (SPWM) control has no effect on balancing the neutral-point voltage. Based on the basic control principle of DPWM, the relationship between the reference space voltage vector and the neutral-point current is analyzed. The proposed method suppresses the low frequency oscillation of the neutral-point voltage by keeping the switches of a certain phase no switching in one carrier cycle. So the operating time of the positive and negative small vectors is equal. Comparing with the conventional SPWM control method, the proposed DPWM control method suppresses the low frequency oscillation of the neutral-point voltage, decreases the output waveform harmonics, and increases both the output waveform quality and the system efficiency. An experiment has been realized by a neutral-point clamped (NPC) three-level inverter prototype based on STM32F407-CPLD. The experimental results verify the correctness of the theoretical analysis and the effectiveness of the proposed DPWM method.
A Modified Single-Phase Transformerless Z-Source Photovoltaic Grid-Connected Inverter
Liu, Hongpeng ; Liu, Guihua ; Ran, Yan ; Wang, Gaolin ; Wang, Wei ; Xu, Dianguo ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1217~1226
DOI : 10.6113/JPE.2015.15.5.1217
In a grid-connected photovoltaic (PV) system, the traditional Z-source inverter uses a low frequency transformer to ensure galvanic isolation between the grid and the PV system. In order to combine the advantages of both Z-source inverters and transformerless PV inverters, this paper presents a modified single-phase transformerless Z-source PV grid-connected inverter and a corresponding PWM strategy to eliminate the ground leakage current. By utilizing two reversed-biased diodes, the path for the leakage current is blocked during the shoot-through state. Meanwhile, by turning off an additional switch, the PV array is decoupled from the grid during the freewheeling state. In this paper, the operation principle, PWM strategy and common-mode (CM) characteristic of the modified transformerless Z-source inverter are illustrated. Furthermore, the influence of the junction capacitances of the power switches is analyzed in detail. The total losses of the main electrical components are evaluated and compared. Finally, a theoretical analysis is presented and corroborated by experimental results from a 1-kW laboratory prototype.
Single-Phase Multilevel PWM Inverter Based on H-bridge and its Harmonics Analysis
Choi, Woo-Seok ; Nam, Hae-Kon ; Park, Sung-Jun ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1227~1234
DOI : 10.6113/JPE.2015.15.5.1227
The efficient electric power demand management in electric power supply industry is currently being changed by distributed generation. Meanwhile, small-scale distributed generation systems using renewable energy are being constructed worldwide. Several small-scale renewable distributed generation systems, which can supply electricity to the grid at peak load of the grid as per policy such as demand response programs, could help in the stability of the electric power demand management. In this case, the power quality of the small-scale renewable distributed generation system is more significant. Low prices of power semiconductors and multilevel inverters with high power quality have been recently investigated. However, the conventional multilevel inverter topology is unsuitable for the small-scale renewable distributed generation system, because the number of devices of such topology increases with increasing output voltage level. In this paper, a single-phase multilevel inverter based on H-bridge, with DC_Link divided by bi-directional switches, is proposed. The proposed topology has almost half the number of devices of the conventional multilevel inverter topology when these inverters have the same output voltage level. Double Fourier series solution is mainly used when comparing PWM output harmonic components of various inverter topologies. Harmonic components of the proposed multilevel inverter, which have been analyzed by double Fourier series, are compared with those of the conventional multilevel inverter. An inverter prototype is then developed to verify the validity of the theoretical analysis.
An Improved SVPWM Control of Voltage Imbalance in Capacitors of a Single-Phase Multilevel Inverter
Ramirez, Fernando Arturo ; Arjona, Marco A. ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1235~1243
DOI : 10.6113/JPE.2015.15.5.1235
This paper presents a modified Space Vector Pulse Width Modulation Technique (SVPWM), which solves the well-known problem of voltage imbalance in the capacitors of a single-phase multilevel inverter. The proposed solution is based on the measurement of DC voltage levels at each capacitor of the inverter DC bus. The measurements are then used to adjust the size of the active vectors within the SVPWM algorithm to keep the voltage waveform sinusoidal regardless of any voltage imbalance on the DC link capacitors. When a voltage deviation exceeds a predetermined hysteresis band, the correspondent voltage vector is restricted to restore the voltage level to an acceptable threshold. Hence, the need for external voltage regulators for the voltage capacitors is eliminated. The functionality of the proposed algorithm is successfully demonstrated through simulations and experiments on a grid tied application.
Stability Enhancement of Four-in-Wheel Motor-Driven Electric Vehicles Using an Electric Differential System
Hartani, Kada ; Merah, Abdelkader ; Draou, Azeddine ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1244~1255
DOI : 10.6113/JPE.2015.15.5.1244
This paper presents a new multi-machine robust control based on an electric differential system for electric vehicle (EV) applications which is composed of four in-wheel permanent magnet synchronous motors. It is based on a new master-slave direct torque control (DTC) algorithm, which is used for the control of bi-machine traction systems based on a speed model reference adaptive system observer. The use of an electric differential in the design of a new EV constitutes a technological breakthrough. A classical system with a multi-inverter and a multi-machine comprises a three-phase inverter for each machine to be controlled. Another approach consists of only one three-phase inverter for several permanent magnet synchronous machines. The control of multi-machine single-inverter systems is the subject of this study. Several methods have been proposed for the control of multi-machine single-inverter systems. In this study, a new master-slave based DTC strategy is developed to generate an electric differential system. The entire system is simulated by Matlab/Simulink. The simulation results show the effectiveness of the new multi-machine robust control based on an electric differential system for use in EV applications.
A Novel Double-Loop Vector Control Strategy for PMSMs Based on Kinetic Energy Feedback
Wang, Anbang ; Wang, Qunjing ; Jiang, Weidong ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1256~1263
DOI : 10.6113/JPE.2015.15.5.1256
A novel vector control strategy for a permanent magnet synchronous motor (PMSM) based on the kinetic energy stored in the rotor is proposed in this paper. The novel strategy is composed of two closed loops, in which the current loop is the inner loop, and the kinetic energy serves as the outer loop. The theoretical basis and the design procedure of the two loops are given. The feasibility of the proposed control strategy is verified by experimental results. When compared with traditional vector control strategies, the proposed vector control strategy based on energy feedback has better dynamic performance. In addition, an effective estimation solution for the load variation is put forward.
Compensation of Periodic Magnetic Saturation Effects for the High-Speed Sensorless Control of PMSM Driven by Inverter Output Power Control-based PFC Strategy
Lee, Kwang-Woon ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1264~1273
DOI : 10.6113/JPE.2015.15.5.1264
An inverter output power control based power factor correction (PFC) strategy is being extensively used for permanent magnet synchronous motor (PMSM) drives in appliances because such a strategy can considerably reduce the cost and size of the inverter. In this strategy, PFC circuits are removed and large electrolytic DC-link capacitors are replaced with small film capacitors. In this application, the PMSM d-q axes currents are controlled to produce ripples, the frequency of which is twice that of the AC main voltage, to obtain a high power factor at the AC mains. This process indicates that the PMSM operates under periodic magnetic saturation conditions. This paper proposes a back electromotive-force (back-EMF) estimator for the high-speed sensorless control of PMSM operating under periodic magnetic saturation conditions. The transfer function of the back-EMF estimator is analyzed to examine the effect of the periodic magnetic saturation on the accuracy of the estimated rotor position. A simple compensation method for the estimated position errors caused by the periodic magnetic saturation is also proposed in this paper. The effectiveness of the proposed method is experimentally verified with the use of a PMSM drive for a vacuum cleaner centrifugal fan, wherein the maximum operating speed reaches 30,000 rpm.
MRAS Based Speed Estimator for Sensorless Vector Control of a Linear Induction Motor with Improved Adaptation Mechanisms
Holakooie, Mohammad Hosein ; Taheri, Asghar ; Sharifian, Mohammad Bagher Bannae ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1274~1285
DOI : 10.6113/JPE.2015.15.5.1274
This paper deals with model reference adaptive system (MRAS) speed estimators based on a secondary flux for linear induction motors (LIMs). The operation of these estimators significantly depends on an adaptation mechanism. Fixed-gain PI controller is the most common adaptation mechanism that may fail to estimate the speed correctly in different conditions, such as variation in machine parameters and noisy environment. Two adaptation mechanisms are proposed to improve LIM drive system performance, particularly at very low speed. The first adaptation mechanism is based on fuzzy theory, and the second is obtained from an LIM mechanical model. Compared with a conventional PI controller, the proposed adaptation mechanisms have low sensitivity to both variations of machine parameters and noise. The optimum parameters of adaptation mechanisms are tuned using an offline method through chaotic optimization algorithm (COA) because no design criterion is given to provide these values. The efficiency of MRAS speed estimator is validated by both numerical simulation and real-time hardware-in-the-loop (HIL) implementations. Results indicate that the proposed adaptation mechanisms improve performance of MRAS speed estimator.
A Modified Capacitor Current Feedback Active Damping Approach for Grid Connected Converters with an LCL Filter
Wan, Zhiqiang ; Xiong, Jian ; Lei, Ji ; Chen, Chen ; Zhang, Kai ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1286~1294
DOI : 10.6113/JPE.2015.15.5.1286
Capacitor current feedback active damping is extensively used in grid-connected converters with an LCL filter. However, systems tends to become unstable when the digital control delay is taken into account, especially in low switching frequencies. This paper discusses this issue by deriving a discrete model with a digital control delay and by presenting the stable region of an active damping loop from high to low switching frequencies. In order to overcome the disadvantage of capacitor current feedback active damping, this paper proposes a modified approach using grid current and converter current for feedback. This can expand the stable region and provide sufficient active damping whether in high or low switching frequencies. By applying the modified approach, the active damping loop can be simplified from fourth-order into second-order, and the design of the grid current loop can be simplified. The modified approach can work well when the grid impedance varies. Both the active damping performance and the dynamic performance of the current loop are verified by simulations and experimental results.
An Empirical Study on the Application of Lead-Acid Batteries to ESSs and Performance Improvement Methods
Jung, Hyun-Chul ; Heo, Hoon ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1295~1304
DOI : 10.6113/JPE.2015.15.5.1295
In this paper, an approach to extend the life of lead-acid batteries through the elimination of sulfation with "rest time" using the pulse current of a conventional DPV (Differential Pulse Voltammetry) method is discussed. A new rest time without "0" current in "saw-tooth" pattern pulses is proposed to overcome the "0" current (blackout period), which is a shortcoming of DPV. This will enable the proposed method to be used in the loaded state. In the proposed approach, ESSs (Energy Storage Systems) were discharged for 5 h twice per day for 6 months on weekdays. To observe the changes in the lifespan of the systems, for the same period, the changes in the impedances of lead-acid batteries which were being charged e without charging and discharging were measure and compared. This study is focused on determining the effectiveness of lead-acid batteries as ESSs.
A Magnetic Energy Recovery Switch Based Terminal Voltage Regulator for the Three-Phase Self-Excited Induction Generators in Renewable Energy Systems
Wei, Yewen ; Kang, Longyun ; Huang, Zhizhen ; Li, Zhen ; Cheng, Miao miao ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1305~1317
DOI : 10.6113/JPE.2015.15.5.1305
Distributed generation systems (DGSs) have been getting more and more attention in terms of renewable energy use and new generation technologies in the past decades. The self-excited induction generator (SEIG) occupies an important role in the area of energy conversion due to its low cost, robustness and simple control. Unlike synchronous generators, the SEIG has to absorb capacitive reactive power from the outer device aiming to stabilize the terminal voltage at load changes. This paper presents a novel static VAR compensator (SVC) called a magnetic energy recovery switch (MERS) to serve as a voltage controller in SEIG powered DGSs. In addition, many small scale SEIGs, instead of a single large one, are applied and devoted to promote the generation efficiency. To begin with, an expandable mathematic model based on a d-q equivalent circuit is created for parallel SEIGs. The control method of the MERS is further improved with the objective of broadening its operating range and restraining current harmonics by parameter optimization. A hybrid control strategy is developed by taking both of the stand-alone and grid-connected modes into consideration. Then simulation and experiments are carried out in the case of single and double SEIG(s) generation. Finally, the measurement results verify that the proposed DGS with SVC-MERS achieves a better stability and higher feasibility. The major advantages of the mentioned variable reactive power supplier, when compared to the STATCOM, include the adoption of a small DC capacitor, line frequency switching, simple control and less loss.
Power Conditioning for a Small-Scale PV System with Charge-Balancing Integrated Micro-Inverter
Manoharan, Mohana Sundar ; Ahmed, Ashraf ; Seo, Jung-Won ; Park, Joung-Hu ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1318~1328
DOI : 10.6113/JPE.2015.15.5.1318
The photovoltaic (PV) power conditioning system for small-scale applications has gained significant interest in the past few decades. However, the standalone mode of operation has been rarely approached. This paper presents a two-stage multi-level micro-inverter topology that considers the different operation modes. A multi-output flyback converter provides both the DC-Link voltage balancing for the multi-level inverter side and maximum power point tracking control in grid connection mode in the PV stage. A modified H-bridge multi-level inverter topology is included for the AC output stage. The multi-level inverter lowers the total harmonic distortion and overall ratings of the power semiconductor switches. The proposed micro-inverter topology can help to decrease the size and cost of the PV system. Transient analysis and controller design of this micro-inverter have been proposed for stand-alone and grid-connected modes. Finally, the system performance was verified using a 120 W hardware prototype.
Employing Multi-Phase DG Sources as Active Power Filters, Using Fuzzy Logic Controller
Ghadimi, Ali Asghar ; Ebadi, Mazdak ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1329~1337
DOI : 10.6113/JPE.2015.15.5.1329
By placing distributed generation power sources beside a big nonlinear load, these sources can be used as a power quality enhancer, while injecting some active power to the network. In this paper, a new scheme to use the distributed generation power source in both operation modes is presented. In this scheme, a fuzzy controller is added to adjust the optimal set point of inverter between compensating mode and maximum active power injection mode, which works based on the harmonic content of the nonlinear load. As the high order current harmonics can be easily rejected using passive filters, the DG is used to compensate the low order harmonics of the load current. Multilevel transformerless cascade inverters are preferred in such utilization, as they have more flexibility in current/voltage waveform. The proposed scheme is simulated in MATLAB/SIMULINK to evaluate the circuit performance. Then, a 1kw single phase prototype of the circuit is used for experimental evaluation of the paper. Both simulative and experimental results prove that such a circuit can inject a well-controlled current with desired harmonics and THD, while having a smaller switching frequency and better efficiency, related to previous 3-phase inverter schemes in the literature.
DC Injection Control for Grid-Connected Single-Phase Inverters Based on Virtual Capacitor
Wang, Wei ; Wang, Ping ; Bei, Taizhou ; Cai, Mengmeng ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1338~1347
DOI : 10.6113/JPE.2015.15.5.1338
DC injection is a critical issue in transformerless grid-connected inverters. DC injection control based on virtual capacitor has the advantages of low cost, low loss, high accuracy and easy implementation. In this paper, the principle of DC injection control based on virtual capacitor was analyzed. In addition, the applicable conditions, working process, steady state error and advantages were also discussed in detail. The design of the control parameters based on virtual capacitor was proposed in a grid-connected inverter with LCL filter. The robustness of the control parameters was also discussed. Simulation and experimental results verify the validity of the analysis and demonstrate that this research has a certain value in engineering applications.
Coordinated Control Strategies with and without Circulating Current in Unified Power Quality
Feng, Xing-tian ; Zhang, Zhi-hua ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1348~1357
DOI : 10.6113/JPE.2015.15.5.1348
Under traditional unified power quality conditioner (UPQC) control, a UPQC series converter (SC) is mainly used to handle grid-side power quality problems while its parallel converter (PC) is mainly used to handle load-side power quality problems. The SC and PC are relatively independent. The SC is usually in standby mode and it only runs when the grid voltage abruptly changes. In this paper, novel UPQC coordinated control strategies are proposed which use the SC to share the reactive power compensation function of the PC especially without grid-side power quality problems. However, in some cases, there will be a circulating current between the SC and the PC, which will probably influence the compensation fashion, the compensation capacity, or the normal work of the UPQC. Through an active power circulation analysis, strategies with and without a circulating current are presented which fuses the reactive power allocation strategy of the SC and the PC, the composite control strategy of the SC and the compensation strategy of the DC storage unit. Both of the strategies effectively solve the SC long term idle problem, limit the influence of the circulating current, optimize all of the UPQC units and reduce the production cost. An analysis, along with simulation andexperimental results, is presented to verify the feasibility and effectiveness of the proposed control strategies.
Super-Twisting Sliding Mode Control Design for Cascaded Control System of PMSG Wind Turbine
Phan, Dinh Hieu ; Huang, ShouDao ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1358~1366
DOI : 10.6113/JPE.2015.15.5.1358
This study focuses on an advanced second-order sliding mode control strategy for a variable speed wind turbine based on a permanent magnet synchronous generator to maximize wind power extraction while simultaneously reducing the mechanical stress effect. The control design based on a modified version of the super-twisting algorithm with variable gains can be applied to the cascaded system scheme comprising the current control loop and speed control loop. The proposed control inheriting the well-known robustness of the sliding technique successfully deals with the problems of essential nonlinearity of wind turbine systems, the effects of disturbance regarding variation on the parameters, and the random nature of wind speed. In addition, the advantages of the adaptive gains and the smoothness of the control action strongly reduce the chatter signals of wind turbine systems. Finally, with comparison with the traditional super-twisting algorithm, the performance of the system is verified through simulation results under wind speed turbulence and parameter variations.
Investigation of a Hybrid HVDC System with DC Fault Ride-Through and Commutation Failure Mitigation Capability
Guo, Chunyi ; Zhao, Chengyong ; Peng, Maolan ; Liu, Wei ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1367~1379
DOI : 10.6113/JPE.2015.15.5.1367
A hybrid HVDC system that is composed of line commutated converter (LCC) at the rectifier side and voltage source converter (VSC) in series with LCC at the inverter side is studied in this paper. The start-up strategy, DC fault ride-through capability, and fault recovery strategy for the hybrid HVDC system are proposed. The steady state and dynamic performances under start-up, AC fault, and DC fault scenarios are analyzed based on a bipolar hybrid HVDC system. Furthermore, the immunity of the LCC inverter in hybrid HVDC to commutation failure is investigated. The simulation results in PSCAD/EMTDC show that the hybrid HVDC system exhibits favorable steady state and dynamic performances, in particular, low susceptibility to commutation failure, excellent DC fault ride-through, and fast fault recovery capability. Results also indicate that the hybrid HVDC system can be a good alternative for large-capacity power transmission over a long distance byoverhead line.
Loss Analysis and Comparison of High Power Semiconductor Devices in 5MW PMSG MV Wind Turbine Systems
Lee, Kihyun ; Suh, Yongsug ; Kang, Yongcheol ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1380~1391
DOI : 10.6113/JPE.2015.15.5.1380
This paper provides a loss analysis and comparison of high power semiconductor devices in 5MW Permanent Magnet Synchronous Generator (PMSG) Medium Voltage (MV) Wind Turbine Systems (WTSs). High power semiconductor devices of the press-pack type IGCT, module type IGBT, press-pack type IGBT, and press-pack type IEGT of both 4.5kV and 6.5kV are considered in this paper. Benchmarking is performed based on the back-to-back type 3-level Neutral Point Clamped Voltage Source Converters (3L-NPC VSCs) supplied from a grid voltage of 4160V. The feasible number of semiconductor devices in parallel is designed through a loss analysis considering both the conduction and switching losses under the operating conditions of 5MW PMSG wind turbines, particularly for application in offshore wind farms. This paper investigates the loss analysis and thermal performance of 5MW 3L-NPC wind power inverters under the operating conditions of various power factors. The loss analysis and thermal analysis are confirmed through PLECS Blockset simulations with Matlab Simulink. The comparison results show that the press-pack type IGCT has the highest efficiency including the snubber loss factor.
Multiple-Load Induction Cooking Application with Three-Leg Inverter Configuration
Sharath Kumar, P. ; Vishwanathan, N. ; Murthy, Bhagwan K. ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1392~1401
DOI : 10.6113/JPE.2015.15.5.1392
Inverter configurations for multiple-load induction cooking applications need development. Inverter configurations for induction cooking applications are used in home appliances based on single coil inverters. For multiple-load configurations, multiple coils are used. They require proper inverters, which provide independent control for each load and have fewer components. This paper presents a three-leg inverter configuration for three load induction cooking applications. Each induction coil powers one induction cooking load. This configuration operates with constant switching frequency and powers individual loads. The output power of the required load is controlled with a phase-shift control technique. This configuration is simulated and experimentally tested with three induction loads. The simulation and experimental results are in good agreement. This configuration can be extended to more loads.
A MOSFET's Driver Applied to High-frequency Switching with Wide Range of Duty Cycles
Zhang, Zhao ; Xie, Shaojun ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1402~1408
DOI : 10.6113/JPE.2015.15.5.1402
A MOSFET's gate driver based on magnetic coupling is investigated. The gate driver can meet the demands in applications for wide range of duty cycles and high frequency. Fully galvanic isolation can be realized, and no auxiliary supply is needed. The driver is insensitive to the leakage inductor of the isolated transformer. No gate resistor is needed to damp the oscillation, and thus the peak output current of the gate driver can be improved. Design of the driving transformer can also be made more flexible, which helps to improve the isolation voltage between the power stage and the control electronics, and aids to enhance the electromagnetic compatibility. The driver's operation principle is analyzed, and the design method for its key parameters is presented. The performance analysis is validated via experiment. The disadvantages of the traditional magnetic coupling and optical coupling have been conquered through the investigated circuit.
A Double Bi-Quad Filter with Wide-Band Resonance Suppression for Servo Systems
Luo, Xin ; Shen, Anwen ; Mao, Renchao ;
Journal of Power Electronics, volume 15, issue 5, 2015, Pages 1409~1420
DOI : 10.6113/JPE.2015.15.5.1409
In this paper, an algorithm using two bi-quad filters to suppress the wide-band resonance for PMSM servo systems is proposed. This algorithm is based on the double bi-quad filters structure, so it is named, "double bi-quad filter." The conventional single bi-quad filter method cannot suppress unexpected mechanical terms, which may lead to oscillations on the load side. A double bi-quad filter structure, which can cancel the effects of compliant coupling and suppress wide-band resonance, is realized by inserting a virtual filter after the motor speed output. In practical implementation, the proposed control structure is composed of two bi-quad filters on both the forward and feedback paths of the speed control loop. Both of them collectively complete the wide-band resonance suppression, and the filter on the feedback path can solve the oscillation on the load side. Meanwhile, with this approach, in certain cases, the servo system can be more robust than with the single bi-quad filter method. A step by step design procedure is provided for the proposed algorithm. Finally, its advantages are verified by theoretical analysis and experimental results.