• 전력전자학회논문지
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• 제23권3호
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• pp.182-189
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• 2018

LLC resonant converters or phase-shift full-bridge converters have been widely used as DC - DC converters for rapid charging of electric vehicles (EVs). However, these converters present critical disadvantages, including a large circulating current, which can hinder efficiency and miniaturization in EV battery charger applications. In this paper, a new DC - DC converter topology is proposed for EV rapid chargers. The proposed converter can operate at high frequency despite a high rated power capacity of over 20kW, and the problem of circulating current can be minimized during the entire battery charging time. Owing to these advantages, the proposed converter can achieve a high conversion efficiency of over 97% for EV rapid charger applications. The performance of the proposed converter is verified with 20kW prototypes in this study.

• Journal of Power Electronics
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• 제6권1호
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• pp.45-51
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• 2006

A new high efficiency phase shifted full bridge (PSFB) converter for the power sustaining module of a plasma display panel (PDP) is proposed in this paper. The proposed converter employs a voltage doubler rectifier without an output inductor. Since it has no output inductor, the voltage stresses of the secondary rectifier diodes can be clamped at the output voltage level. No dissipative resistor-capacitor (RC) snubber for rectifier diodes is needed. Therefore, high efficiency, as well as, a low noise output voltage can be realized. Due to the elimination of the large output inductor, it features a simple structure, lower cost, smaller mass and lighter weight. Furthermore, the proposed converter has wide zero voltage switching (ZVS) ranges with low current stresses of the primary switches. Also the resonance between the leakage inductor of the transformer and the capacitor of the voltage doubler cell reduces the current stresses of the rectifier diodes. In this paper, operational principles, an analysis of the proposed converter and experimental results are presented.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2019년도 추계학술대회
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• pp.168-169
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• 2019

본 논문은 친환경자동차용 저전압 DC-DC 컨버터(Low-voltage DC-DC converter, LDC)의 고전력밀도 달성을 위한 스위칭 주파수 선정 및 구조 설계 방법을 소개한다. 위상천이 풀-브릿지(Phase-Shift Full-Bridge, PSFB) 컨버터의 손실 분석을 통해 스위칭 주파수 700kHz 선정하였으며, 냉각수 온도 65℃, 분당 8리터의 유량 기준으로 소자 온도가 110℃ 이내로 관리 되도록 고려하여 구조 설계를 수행했다. 온도 조건을 만족하면서 8kW/L의 높은 전력밀도를 달성하였으며 입력전압 200V-310V, 출력전압 12.8V-15.1V의 전압 범위를 만족하는 1.8kW 최종 시작품을 제작하여 실험으로 검증하였다.

• 전력전자학회논문지
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• 제19권3호
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• pp.283-289
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• 2014

This paper carries out a series of analysis of power system using Gallium Nitride (GaN) FET which has wide band gap (WBG) characteristics comparing to conventional Si MOSFET-used power system. At first, for comparison of each semiconductor device, the switching-transient parameter is quantitatively extracted from released information of GaN FET. And GaN FET model which reflect this dynamic property is configured. By using this model, the performance of GaN FET is analyzed comparing to Si MOSFET. Also, in order to enable a representative assessment on the power system level, Si MOSFET and GaN FET are applied to the most common structure of power system, full-bridge, and each power systems are compared based on various criteria, such as performance, efficiency and power density. The entire process is verified with the aid of mathematical analysis and simulation.

• Journal of Power Electronics
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• 제14권3호
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• pp.413-420
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• 2014

The conventional Phase-Shift Full-Bridge (PSFB) converter has a serious voltage spike because of the ringing between the leakage inductance of the transformer and the parasitic output capacitance of the secondary side rectifier switches. To overcome this problem, an asynchronous active clamp technique employing an auxiliary DC/DC converter has been proposed. However, an exact analyses for designing the auxiliary DC/DC converter has not been presented. Therefore, the amount of power that is supposed to be handled in the auxiliary DC/DC converter is calculated through a precise mode analyses in this paper. In addition, this paper proposes a lossy snubber circuit with hysteresis characteristics to reduce the burden that the auxiliary DC/DC converter should take during the starting interval. This technique results in optimizing the size of the magnetic component of the auxiliary DC/DC converter. The operational principles and the theoretical analyses are validated through experiments with a 48V-to-30V/15A prototype.

• 전력전자학회논문지
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• 제25권1호
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• pp.37-43
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• 2020

This study proposes a 7kW low-voltage DC-DC converter (LDC) using a coupled inductor (CI) for heavy hydrogen electric transport vehicles. The LDC uses a phase-shift manner for soft switching. SiC-MOSFET is used to reduce the loss of reverse recovery current through the use of a high switching frequency. LDC is require large transformer and inductor because of large output current. The size of transformer and inductor can be reduced by deviding the transformer and inductor into two pieces each. This work presents the experimental results of the proposed circuit.

• 전력전자학회논문지
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• 제18권2호
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• pp.131-137
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• 2013

In this paper, the phase-shift full-bridge DC/DC converter with fixed-phase operation inverter is proposed. The proposed circuit consists of two full-bridge inverters which are connected in parallel. While one full-bridge inverter operates as the fixed-phase, it regulates the output voltage by adjusting the phase of the other inverter. During the normal operation period, the proposed circuit makes the less amount of conduction loss of the primary switches and secondary synchronous rectifiers, as well as the less amount of the current ripple of the output inductor, than the conventional phase-shift full-bridge DC/DC converter does. Also, it achieves high efficiency by reducing the snubber loss of the secondary synchronous rectifier. To sum up, the present inquiry analyzes the theoretical characteristics of the proposed circuit, and shows the experimental results from a prototype for 450W power supply.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.445-448
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• 2005

PDP 유지전원단을 위한 고효율을 갖는 새로운 페이지 쉬프트 풀브릿지 컨버터를 제안한다. 제안된 컨버터는 Rectifier로 Voltage Doubler를 사용함으로서, 큰 사이즈의 Output Inductor가 없게 되어 간단한 구조를 가지게 되며 Rectifier Diodes의 전압 스트레스가 출력전압으로 클램핑되어서 스너버회로가 필요없다는 장점을 가지게 된다. 또한 넓은 영전압 스위칭 구간을 가지며, 트랜스포머의 기생성분인 Leakage 인덕터와 Voltage doubler의 캐패시터간의 공진을 이용함으로서 전류가 작은 RMS값을 가지게 되어서 낮은 도통손실과 Rectifier Diode의 전류 스트레스 또한 낮다는 장점을 가지게 된다. 본 논문을 통해 제안된 컨버터의 동작원리와 해석, 실험을 수행하였다.

• 전력전자학회논문지
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• 제19권3호
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• pp.211-219
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• 2014

This paper proposes a low voltage high current LLC resonant converter for Green PC. Green PC is composed of a lot of blade PCs, and it is a centralized system to manage them in computer center. Green PC should require that its power supplies have several characteristics such as low output voltage, high output current, and high power conversion efficiency. Conventional PSFB (Phase Shift Full Bridge) converter is usually used as DC/DC converter for computer power supply because it has high power conversion efficiency thanks to ZVS (Zero Voltage Switching) operation under middle and high load conditions. However, this converter has some problems such as large switching noise and limitation of ZVS operation under light load condition. In order to improve the performance of power supply for Green PC, a new power supply using popular high efficiency LLC resonant converter for low voltage and high current application is proposed in this paper. The proposed power supply has ZVS capability over the entire load range, thus resulting in good efficiency and high switching frequency. Experimental results verify the performance of the proposed power supply for Green PC using 2[kW] (19[V], 105[A]) rated prototype converter.