• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.460-465
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• 1998

Due to high power ratings and low conduction loss, the IGBT has become more attractive in switching power supplies. However, its turn-on and turn-off characteristics cause severe switching loss and switching frequency limitation. This paper proposes 2.4kW, 48V, high efficiency half-bridge DC-DC converter using paralleled IGBT-MOSFET switch concept, where each of IGBT and MOSFET plays its part during on-periods and switching instants. The switching loss is analyzed by using the linearized model and the opteration of the converter are investigated by simulation results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 추계학술대회 논문집 학회본부
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• pp.263-266
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• 1990

In order to high-respone and high-reliability of devices, it depended upon how we can increase the high-frequency of the Inverter, UPS and it's application. but using high-frequency of self turn-off devices, it is important to reduce switching device loss and spike voltage of turn off. This paper proposed new methode about computer simulation of device loss also experimental results with switching device characteristic are presented.

• 한국광학회지
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• 제21권2호
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• pp.69-73
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• 2010

본 논문에서는 광학적으로 비등방성인 폴리머를 이용하여 $90^{\circ}$ TN(Twisted Nematic) 액정셀의 응답시간을 향상시키는 방법을 제안하였다. 액정과 비등방성 폴리머를 일정 비율로 혼합하여 TN 액정셀에 주입한 뒤 UV를 조사하여 폴리머 네트워크를 형성시킴으로써 투과율에 영향을 주지 않고 응답시간을 향상시킬 수 있다. 폴리머 네트워크가 형성되지 않은 TN 액정셀의 turn-off 시간이 16 ms인데 반해 제안된 방법에서는 액정과 비등방성 폴리머의 혼합 비율이 3, 5, 10 wt%로 증가할 때 12, 11, 9 ms로 고속 turn-off가 구현될 수 있다. 또한, turn-off 동작 시 TN 액정셀에서 발생하였던 delay time과 backflow가 폴리머 네트워크의 형성에 의해 크게 개선됨을 확인하였다.

• 한국안전학회지
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• 제8권4호
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• pp.95-100
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• 1993

In power transistor switching circuit have shunt snubber(dv/dt limiting capacitor) and series snubber (di/dt limiting inductor). The shunt snubber is used to reduce the turn-off switching loss and the series snubber is used to reduce the turn-on switching loss. Design procedures are derived for selecting the capacitance, inductor and resistance to limit the peak voltage and current values. The action of snubber is analyzed and applied to the design for safety PWM inverter.

• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.2168-2180
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• 2014

In this paper, a generalized power loss algorithm for multilevel neutral-point clamped (NPC) PWM inverters is presented, which is applicable to any level number of multilevel inverters. In the case of three-level inverters, the conduction loss depends on the MI (modulation index) and the PF (power factor), and the switching loss depends on a switching frequency, turn-on and turn-off energy. However, in the higher level of inverters than the three-level, the loss of semiconductor devices cannot be analyzed by conventional methods. The modulation depth should be considered in addition, to find the different conducting devices depending on the MI. In a case study, the power loss analysis for the three- and five-level NPC inverters has been performed with the proposed algorithm. The validity of the proposed algorithm is verified by simulation for the three-and five-level NPC inverters and experiment for three-level NPC inverter.

• 전력전자학회논문지
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• 제4권4호
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• pp.311-317
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• 1999

본 논문에서는 SEPP-LCC형 부하 공진 고주파 인버터의 한 회로형식을 제안하고, 그 동작원리에 관해서 명확히 하였다. 제안한 인버터는 스위칭 소자 양단에 병렬로 커패시터를 추가함으로써 스위칭 소자의 턴-온과 턴-오프시에 발생하는 스위칭 손실, 노이즈, 스트레스 등을 줄일 수 있다. 범용성 있는 회로해석을 위하여 무차원화 파라미터를 도입하였고, 동작특성 및 평가를 통하여 얻은 특성치를 이용하여 회로를 설계하였다. 또한, 실험을 통하여 이론해석의 정당성을 입증하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2009년도 정기총회 및 추계학술대회 논문집
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• pp.155-157
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• 2009

This paper proposed a soft switching boost converter with an auxiliary circuit, and a modified control method for reduction of switch stress. The proposed converter applies an auxiliary circuit, which is added to the conventional boost converter and used to achieve soft switching for both a main switch and an auxiliary switch. The auxiliary circuit consist of a resonant inductor and two capacitors, an auxiliary switch. The main switch is operated ZVS turn-on, turn-off also auxiliary switch is operated ZCS turn-on, ZVS turn-off. The proposed soft switching boost converter has lower switch loss and higher efficiency than conventional soft switching boost converter.

• Journal of Power Electronics
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• 제9권2호
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• pp.259-266
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• 2009

In order to increase the power density of power converters, reduction of the switching losses at high-frequency switching conditions is one of the most important issues. This paper presents a new gate drive circuit that enables the reduction of switching losses in both the Power MOSFET and the IGBT. A distinctive feature of this method is that both the turn-on loss and the turn-off loss are decreased simultaneously without using a conventional ZVS circuit, such as the quasi-resonant adjunctive circuit. Experimental results of the switching loss of both the Power MOSFET and the IGBT are shown. In addition, an energy recovery circuit suitable for use in IGBTs that can be realized by modifying the proposed gate drive circuit is also proposed. The effectiveness of both the proposed circuits was confirmed experimentally by the buck-chopper circuit.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제12B권1호
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• pp.37-43
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• 2002

This paper proposes a new zero-current switching (ZCS) pulse-width modulation (PWM) switch cell that has no additional conduction loss of the main switch. In this cell, the main switch and the auxiliary switch turn on and turn off under zero current condition. The diodes commutate softly and the reverse recovery problems are alleviated. The conduction loss and the current stress of the main switch are minimized, since the resonating current for the soft switching does not flow through the main switch. Based on the proposed ZCS PWM switch cell, a new family of dc to dc PWM converters is derived. The new family of ZCS PWM converters is suitable for the high power applications employing IGBTs. Among the new family of dc to dc PWM converters, a boost converter was taken as an example and has been analyzed. Design guidelines with a design example are described and verified by experimental results from the 2.5㎾ prototype boost converter operating at 40KHz.

• 한국정보전자통신기술학회논문지
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• 제12권4호
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• pp.449-455
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• 2019

본 논문은 Bridgeless PFC Converter의 환류 다이오드를 SiC SBD(Schottky Barrier Diode)로 제안하여 고효율화를 달성하였다. 또한 Bridgeless PFC Converter의 동작원리에 대한 설명을 통해 Bridgeless PFC Converter에서 환류 다이오드의 도통 구간을 나타내어 환류 다이오드의 손실에 따른 시스템 손실의 기여도를 검증하였고, SiC SBD 소자의 물성 및 역 회복 특성에 따른 장점을 설명하였으며 턴 온 손실과 턴 오프 손실을 측정하여 효율을 비교 분석하고, 소자 단품 특성을 확인하기 위한 다이오드의 역회복 파형 분석을 통하여 소자의 역회복 손실을 계산하였다. 소자 특성을 고려한 시뮬레이션 결과 값을 도출해내어 실제 시스템의 파형 분석 및 비교를 통해 그 결과 값을 검증하였다. 소자 특성을 고려하기 위하여 PSIM의 Thermal Module을 사용하여 시뮬레이션을 진행하였으며, 그 결과로 턴온 손실 0.6W, 턴 오프 손실 20.6W로 전체 스위칭 손실은 22.2W로 나타났다. 시작품 실험을 통하여 분석한 결과 턴온 손실 0.608W, 턴 오프 손실 21.62W로 전체 스위칭 손실 22.228W의 결과 값을 도출하였고, 두 결과 값의 비교로 실험 방법의 타당성을 입증하였다. 또한 최대 효율 94.58%의 고효율을 달성하였다.