• Journal of Power Electronics
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• 제16권1호
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• pp.57-65
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• 2016

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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.1058-1059
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• 2015

This paper describes a low-voltage ride-through method for the permanent magnet synchronous generator (PMSG) wind turbine system at a grid fault. The generator side converter regulates the DC link voltage instead of the grid side converter by storing the surplus active power in the rotor inertia during grid fault by the sliding mode controller. The grid side converter controls the grid active power keeping a maximum power point tracking. Simulation results for small scale PMSG wind turbine verify the efficiency of the control method.

• JSTS:Journal of Semiconductor Technology and Science
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• 제4권3호
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• pp.210-216
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• 2004

In this paper, we propose a noncoherent On-Off Keying (OOK) Ultra Wide Band (UWB) system based on power detection with noise power calibration for low power applications. The proposed UWB system achieves good bit error rate performance which is favorably comparable to that of the system using the ideal adaptive threshold, while maintaining simple receiver structure, In addition, low power Analog Front-End (AFE) blocks for the proposed noncoherent UWB transceiver are proposed and verified using CMOS technology. Simulation results on the pulse generator, delay time generator and 1-bit Analog-to-Digital (AID) converter show feasibility of the proposed UWB AFE system.

• 신재생에너지
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• 제9권4호
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• pp.25-31
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• 2013

This paper describes an electrical linear generator (IntELG) based on permanent magnets, containing heaving buoy, and its applications for the floating wave energy converters riding in parallel waves. The permanent magnets are integrated with the heaving buoy as a component and the integrated component is configured within the cylindrical IntELG to be filled with fluid. Thus, the IntELG can effectively be applied for the power-take-off of the floating wave energy converter riding in parallel waves. Typical applications are exampled with the Pelamis and Anaconda and they are investigated for the diversely redundant power source of nuclear power plant and the cooperation with submerged tunnel(s).

• Journal of Electrical Engineering and Technology
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• 제3권2호
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• pp.254-262
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• 2008

This paper presents an active use of doubly-fed induction-generator(DFIG)-based variable-speed wind-turbine for voltage control in power system operation. For reasonable simulation studies, a detail dynamic model of a DFIG-based wind-turbine grid-connected system is presented. For the research objective, an innovative reactive power control scheme is proposed that manipulates dynamically the reactive power from the voltage source converter(VSC) with taking into account its operating state and limits.

• 전력전자학회논문지
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• 제14권1호
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• pp.15-22
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• 2009

본 논문은 소형 풍력발전용 영구자석형 동기발전기에서 고정자 자속과 역기전력을 이용한 센서리스 제어방법을 제안한다. 기존의 다이오드와 DC-부스트 컨버터를 사용한 소형 풍력발전용 컨버터와는 달리 2-Leg 3상 PWM 컨버터를 사용하여 발전기를 구동한다. 이는 기존의 컨버터와 비교하여 가격적으로 뒤지지 않으며, 발전기의 벡터제어가 가능하여 최대출력 제어시 발전 효율향상을 확인할 수 있다. 그리고 센서리스 제어 알고리즘을 적용하여 속도 측정을 위해 사용되는 엔코더를 제거하므로 시스템의 가격을 저감시킨다. 제안된 알고리즘은 PSIM 시뮬레이션을 사용하여 컨버터 제어 성능과 발전기의 최대 출력 제어의 타당성을 검증한다.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권1호
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• pp.8-16
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• 2012

Fixed speed wind turbine generators system that uses induction generator as a wind generator has the stability problem similar to a synchronous generator. On the other hand, doubly fed induction generator (DFIG) has the flexibility to control its real and reactive powers independently while being operated in variable speed mode. This paper focuses on a scheme where IG is stabilized by using DFIG during grid fault. In that case, DFIG will be heavily stressed and a remedy should be found out to protect the frequency converter as well as to allow the independent control of real and reactive powers without loosing the synchronism. For that purpose, a crowbar protection switch or DC-link protecting device can be considered. This paper presents a comparative study between two protective schemes, a crowbar circuit connected across the rotor of the DFIG and a protective device connected in the DC-link circuit of the frequency converter. Simulation analysis by using PSCAD/EMTDC shows that both schemes could effectively protect the DFIG, but the latter scheme is superior to the former, because of less circuitry involved.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.198-200
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• 2007

A linear generator driven by hydrogen (or other kind of fuel) combustion engine requires special consideration for starting because of its none-conventional way of operation. This study investigates the possibility of replacing mechanical (hydraulic) start-up with electrical motoring. Simulation study based on 1 kW prototype system shows that the mover position of a linear generator can be controlled with a proper current control of power converter.

• Advances in Computational Design
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• 제8권3호
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• pp.237-253
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• 2023

Torque ripple content and variable switching frequency operation of conventional direct torque control (DTC) are reduced by the integration of space vector modulation (SVM) into DTC. Integration of space vector modulation to conventional direct torque control known as SVM-DTC. It had been more frequently used method in renewable energy and machine drive systems. In this paper, SVM-DTC is used to control the rotor side converter (RSC) of a wind driven doubly-fed induction generator (DFIG) because of its advantages such as reduction of torque ripples and constant switching frequency operation. However, flux and torque ripples are still dominant due to distorted current waveforms at different operations of the wind turbine. Therefore, to smoothen the torque profile a Neural Network Controller (NNC) based SVM-DTC has been proposed by replacing the PI controller in the speed control loop of the wind turbine controller. Also, stability analysis and simulation study of DFIG using process reaction curve method (RRCM) are presented. Validation of simulation study in MATLAB/SIMULINK environment of proposed wind driven DFIG system has been performed by laboratory developed prototype model. The proposed NNC based SVM-DTC yields superior torque response and ripple reduction compared to other methods.

• Journal of Power Electronics
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• 제15권5호
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• pp.1149-1157
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• 2015

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.