• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제29권4호
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• pp.250-254
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• 2016

Currently, power conversion system which converts AC to DC Power is applied in domestic urban railway. The diode rectifier is used in most of them. However the diode rectifier can not control the output voltage and can not regenerate power as well. On the other hand, PWM (pulse width modulation) converter using IGBT (isolated gate bipolar transistor) can control output voltage, allowing it to reduce the output voltage drop. Moreover the Bi-directional conduction regenerates power which does not require additional device for power regeneration control. This paper compared the simulation results for the DC power supply system on both the diode rectifier and the PWM converter. Under the same load condition, simulation circuit for each power supply system was constructed with the PSIM (performance simulation and modeling tool) software. The load condition was set according to the resistance value of the currently operating impedance of light rail line, and the line impedance was set according to the distance of each substations. The train was set using a passive resistor. PI (proportional integral) controller was applied to regulate the output voltage. PSIM simulation was conducted to verify that the PWM Converter was more efficient than the diode rectifier in DC Traction power supply system.

• Journal of Power Electronics
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• 제18권2호
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• pp.407-417
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• 2018

A novel family of Buck mode three-level direct ac converters with a high frequency link is proposed. These converters can transfer an unsteady high ac voltage with distortion into a regulated sinusoidal voltage with a low THD at the same frequency. The circuit configuration is constituted of a three-level converter, high frequency transformer, cycloconverter, as well as input and output filters. The topological family includes forward, push-pull, half-bridge, and full-bridge modes. In order to achieve a reliable three-level ac-ac conversion, and to overcome the surge voltage and surge current of the cycloconverter, a phase-shifted control strategy is introduced in this paper. A prototype is presented with experimental results to demonstrate that the proposed converters have five advantages including high frequency electrical isolation, lower voltage stress of the power switches, bi-directional power flow, low THD of the output voltage, and a higher input power factor.

• Journal of Power Electronics
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• 제7권1호
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• pp.28-37
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• 2007

A new PWM-controlled quasi-resonant converter for a high efficiency PDP sustaining power module is proposed in this paper. The load regulation of the proposed converter can be achieved by controlling the ripple of the resonant voltage across the resonant capacitor with a bi-directional auxiliary circuit, while the main switches are operating at a fixed duty ratio and fixed switching frequency. Hence, the waveforms of the currents can be expected to be optimized from the view-point of conduction loss. Furthermore, the proposed converter has good ZVS capability, simple control circuits, no high voltage ringing problem of rectifier diodes, no DC offset of the magnetizing current and low voltage stresses of power switches. In this paper, operational principles, features of the proposed converter, and analysis and design considerations are presented. Experimental results demonstrate that the output voltage can be controlled well by the auxiliary circuit using the PWM method.

• The Transactions of the Korean Institute of Power Electronics
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• 제19권5호
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• pp.422-430
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• 2014

This study proposes a small-signal model and control design for a two-stage DC-DC-AC converter to investigate its dynamic characteristics in relation to battery energy storage system. When the circuit analysis of the two-stage DC-DC-AC converter is attempted simultaneously, the mathematical procedure of deriving the dynamic equation is complex and difficult. The main idea of modeling the two-stage DC-DC-AC converter states that this topology is separated into a bidirectional DC-DC converter and a single-phase inverter with an equivalent current source corresponding to that of the inverter or converter. The dynamic equations for the separated converter and inverter are then derived using the state-space averaging technique. The procedures of building the small-signal model of the two-stage DC-DC-AC converter are described in detail. Based on the derived small-signal model, the individual controllers are designed through a frequency-domain analysis. The simulation and experimental results verify the validity of the proposed modeling approach and controller design.

• Proceedings of the KIPE Conference
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.389-390
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• 2016

본 논문에서는 마일드하이브리드 차량용 양방향 LDC의 동작 신뢰성 향상을 위해 2병렬 구성된 1.8kW급 LDC의 설계 및 제어에 대해 기술한다. 양방향 LDC 구현을 위한 최적 회로방법 및 병렬 구동을 위한 제어 방법에 대해 고찰하고 Working Sample 수준의 실험세트 제작내용 및 실험 결과를 제시한다.

• Proceedings of the KIPE Conference
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.279-280
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• 2016

전기자동차를 위한 양방향 탑재형 충전기의 장내구성을 달성하기 위해 전해캐패시터를 사용하지 않는 전력변환장치가 요구된다. 본 논문에서는 V2G-V2H 기능을 갖는 무 전해캐패시터 양방향 탑재형 충전기의 제어알고리즘을 제안한다. 제안하는 양방향 충전기는 정현파 충전방식이 적용되었고 인버터만 제어하여 V2G-G2V-V2H 모드전환이 끊김없는 장점을 갖는다 제안하는 알고리즘을 검증하기 위한 3.3kW급 시작품의 시험결과로 타당성을 검증하였다.

• Proceedings of the KIPE Conference
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• 전력전자학회 2007년도 추계학술대회 논문집
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• pp.21-23
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• 2007

In this paper a high efficiency bi-directional DC-DC converter for hybrid vehicles is proposed. The proposed converter a three-phase half-bridge interleaved ZVS converter, is designed to have high efficiency in the main operation range. The component ratings are calculated, the actual devices are selected, and the efficiency analysis has been performed to determine optimal ZVS range. The input and output current ripples are significantly reduced due to the interleaved operation. The dual loop control for the interleaved three-phase converter is also presented. To confirm the proposed convert ter, The simulation and experimental results are presented.

• Proceedings of the KIPE Conference
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• 전력전자학회 2013년도 전력전자학술대회 논문집
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• pp.279-280
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• 2013

본 논문에서는 3상 양방향 절연형 인터리브드 DC-DC 컨버터의 병렬 제어기법에 대해 기술한다. 대전력 적용 시, DC-DC 컨버터를 단독으로 운전하는 것이 아닌 병렬로 연결하여 운전을 하게 되는데 이때 발생하는 전류의 불평형을 해결하기 위하여 부스트 모드와 벅 모드에서 저전압측의 전압을 제어하는 전압제어기에 각 컨버터의 전류차를 보상하는 전류제어기를 제안하였며 각 모드에서 전류의 불평형이 보상되는 것을 실험을 통해 검증하였다.

• Proceedings of the KIPE Conference
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• 전력전자학회 2013년도 전력전자학술대회 논문집
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• pp.20-21
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• 2013

본 논문에서는 양방향 충전기용 DC/DC 컨버터와 같이 입력전압과 출력전압이 가변하는 제어시스템에서 비시변 시비율 전달함수를 구현하여 제어특성을 개선하고자 한다. 기존제어기 설계에 의해 설계된 이득을 사용하여 제어를 행할 경우 입력전압의 변동에 따라 제어특성이 가변한다. 전압제어기의 각 이득을 시비율의 역수를 취하여 변화함으로서 전체 제어블록에서 시비율 항을 등가적으로 제거할 수 있는 방법이다. 따라서 본 논문에서 제안된 비시변 시비율 전담함수를 양방향 충전기용 DC/DC컨버터에 적용하여 PSIM을 이용한 시뮬레이션과 실험을 통해 타당성과 우수성을 검증하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제60권3호
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• pp.544-551
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• 2011

This paper presents the circuit arrangement and effective control method of regenerative energy storage system for an electric vehicle using super-capacitors as the braking energy storage element. A bi-directional controlled current flow of the DC-DC converters with the capacitor bank is connected in parallel with battery, and is controlled so that the whole of the braking energy is effectively absorbed into the capacitors and released back to the electric motor upon acceleration. The converter needs the series-parallel switching circuit for making the best use of the series capacitors and for limiting the step-up ratio of the boost converter. The proposed methods are verified by computer simulation and experimental set-up. They are usefully applied to the electric vehicles such as green cars, electric motorcycles, bike, etc which are power- supplied by the electric batteries.