• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권1호
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• pp.34-41
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• 1999

A three-level ZCT(Zero Current Transition) IGBT inverter is presented for high power IGBT inverters. The concept of ZCT for the conventional boost converter is extended to the three-level inverter. Moreover, in order to improve the reliability of inverter, midpoint charge balance problem of the three-level inverter is analyzed with respect 150kw, 20kHz prototype are presented to verify the principle of ZCT Operation.

• 전력전자학회논문지
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• 제18권4호
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• pp.359-366
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• 2013

This paper proposes a zero-current-transition(ZCT) synchronous buck converter using auxiliary circuit with soft-switching for light weight and high efficiency. In this scheme, an auxiliary circuit is added to the conventional synchronous rectifier buck converter and used to achieve soft-switching condition for both the main switch and synchronous switch. In addition, the switch in the auxiliary circuit operates under soft-switching conditions. Thus, the proposed converter provides a higher efficiency. The basic operations, in this paper, are discussed and design guidelines are presented. The usefulness of the proposed converter is verified on a 200KHz, 20 W prototype converter.

• Journal of Power Electronics
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• 제11권1호
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• pp.1-9
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• 2011

This paper describes a two quadrant bidirectional soft switching converter for ultra capacitor interface circuits. The total efficiency of the energy storage system in terms of size and cost can be increased by a combination of batteries and ultra capacitors. The required system energy is provided by a battery, while an ultra capacitor is used at high load power pulses. The ultra capacitor voltage changes during charge and discharge modes, therefore an interface circuit is required between the ultra capacitor and the battery. This interface circuit must have good efficiency while providing bidirectional power conversion to capture energy from regenerative braking, downhill driving and the protecting ultra capacitor from immediate discharge. In this paper a fully soft switched two quadrant bidirectional soft switching converter for ultra capacitor interface circuits is introduced and the elements of the converter are reduced considerably. In this paper, zero voltage transient (ZVT) and zero current transient (ZCT) techniques are applied to increase efficiency. The proposed converter acts as a ZCT Buck to charge the ultra capacitor. On the other hand, it acts as a ZVT Boost to discharge the ultra capacitor. A laboratory prototype converter is designed and realized for hybrid vehicle applications. The experimental results presented confirm the theoretical and simulation results.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.256-262
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• 2018

This study introduces a novel Soft Switching (SS) Pulse Width Modulated (PWM) AC-DC boost converter. In the proposed converter, the main switch is turned on with Zero Voltage Transition (ZVT) and turned off with Zero Current Transition (ZCT). The main diode is turned on with Zero Voltage Switching (ZVS) and turned off with Zero Current Switching (ZCS). The auxiliary switch is turned on and off with ZCS. All auxiliary semiconductor devices are turned on and off with SS. There is no extra current or voltage stress on the main semiconductor devices. The majority of switching energies are transferred to the output by auxiliary transformer. Thus, the current stress of auxiliary switch is significantly reduced. Besides, the proposed converter has simple structure and ease of control due to common ground. The theoretical analysis of the proposed converter is verified by a prototype with 100 kHz switching frequency and 500 W output power. Furthermore, the efficiency of the proposed converter is 98.9% at nominal output power.

• 전력전자학회논문지
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• 제24권5호
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• pp.372-378
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• 2019

This study proposes a new zero-current-zero-voltage-transition (ZCZVT) boost-flyback converter using a soft switching auxiliary circuit. The proposed converter integrates the boost and flyback converters to increase the voltage with a low duty ratio. The main and auxiliary switches turn the ZCZVT conditions on and off. Thus, the proposed converter has high efficiency. The voltage gain at the steady state is derived, and the inductor volt-second balance and the design guidelines are presented. Finally, the performance of the proposed converter is validated by experimental results from a 200 W, 30 V DC input, 400 V DC output, and 200 kHz boost-flyback converter prototype.

• 조명전기설비학회논문지
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• 제29권1호
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• pp.80-85
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• 2015

In the issues of interleaved topology which have been in limelight as high power converter, various soft-switching methods are studied to reduce switching losses in high power application. The interleaved ZCT converter has an additional filter inductor to reduce losses of diodes during reverse recovery process. However, additional current conduction modes are occurred by the inductor, we need to analyze switching losses with inductor values on each mode. In this paper, current conduction modes and boundary conditions of interleaved ZCT converter are analyzed. In the conclusion, the minimum of switching losses in converter operation modes is analyzed by calculating switching losses.

• 전력전자학회논문지
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• 제18권6호
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• pp.547-555
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• 2013

This paper proposes the interleaved buck converter using a soft switching auxiliary circuit. In this scheme, an auxiliary circuit is added to the conventional interleaved buck converter and used to achieve soft-switching conditions for both the main switch and freewheeling diode. In addition, the switch in the auxiliary circuit operates under soft-switching conditions. Also, according to the input to output conditions, the main switch achieved zero-current-transition(ZCT) or zero-current & zero-voltage-transition(ZCZVT) at turn on. Thus, the proposed interleaved buck converter provides a higher efficiency. The basic operations, in this paper, are discussed and design guidelines are presented. The usefulness of the proposed converter is verified on a 200kHz, 180W prototype converter.

• 전력전자학회논문지
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• 제6권6호
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• pp.556-563
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• 2001

본 논문에서는, 기존의 PWM 방식의 컨버터와 공진형 컨버터의 단점을 보완하면서 이들의 장점을 가지는 새로운 형태의 ZCT 벅 컨버터를 소개한다. 제안한 회로는 기존의 벅 컨버터에 보조화를 추가하여 주 스위치와 다이로드의 스위칭천이 순간에만 소프트 스위칭 조건을 제공함으로써 전체적인 동작은 벅 컨버터와 동일하게 된다. 아울러 보조회로에서의 부가적인 손실은 존재하지 않는다. 본 논문에서는 제안된 회로의 동작을 분석하고 이를 바탕으로 보조회로에서의 소자값 결정에 도움이 되는 설계 방식을 제공한다. 또한 제안한 회로의 동작 및 유용성을 확인하기 위하여 실험을 행하였다.

• 전력전자학회논문지
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• 제11권2호
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• pp.149-158
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• 2006

본 논문에서는 기존에 널리 사용되는 펄스폭 변조 (Pulse width modulation : PWM) 방식의 컨버터와 공진형 컨버터의 장점을 활용하고 단점을 보완할 수 있는 새로운 형태의 영전류 천이형 (Zero current transition : ZCT) 부우스트 컨버터를 제안한다. 제안한 회로는 기존의 PWM 부우스트 컨버터에 보조회로를 추가하여 주 스위치와 출력 다이오드의 스위칭 천이 순간에만 소프트 스위칭 조건을 제공함으로써 전체적인 동작은 기존의 부우스트 컨버터와 크게 차이가 없도록 하였다. 아울러, 보조회로에서의 부가적인 손실 역시 존재하지 않으므로 해서 고효율이 가능하게 된다. 본 논문에서는 제안한 회로의 동작을 분석하고 이를 바탕으로, 보조 회로의 소자값 결정에 도움이 되는 설계방식을 제공한다. 또한, 실험을 통하여 제안한 회로의 동작 원리 및 유용성을 검증하였다.

• 전력전자학회논문지
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• 제23권6호
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• pp.397-402
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• 2018

In this study, a high-efficiency flyback converter that uses a soft-switching auxiliary circuit is proposed. The structure of the proposed converter adds an inductor, switch, diode, and capacitor to the conventional flyback converter. The switch in the auxiliary circuit and the main switch are turned on and off under soft-switching conditions. Therefore, the switching losses of the proposed flyback converter are considerably smaller than those of conventional flyback converters. The performance of the proposed flyback converter is validated by experiments on a 100 W single-output flyback converter prototype, and design guidelines are presented.