• 전력전자학회논문지
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• 제4권1호
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• pp.19-25
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• 1999

본 연구는 새로운 영전압, 영전류 스위칭 Forward 컨버터에 관한 것으로 종래의 하드 스위칭(Hard-Switching) Forward 컨버터에 있어서 Turn-off 및 Turn-off시 발생되는 스위칭 손실 및 출력 다이오드 역회복 특성에 따른 손실증가와 스위칭시 발생되는 기생진동을 Forward 컨버터에 있어서 1차측 주 스위칭소자 및 2차측 출력 정류다이오드와 병렬로 무손실 스너버를 적용함으로써 Forward 컨버터의 1차측 스위칭 소자의 Turn-off 및 Turn-on시 영전압, 영전류 스위칭을 이룰 수 있고, 출력 정류다이오드도 영전압, 영전류 스위칭 됨으로 다이오드의 역회복손실 및 기생 진동에 따른 EMI(Electro-Magnetic Interference)를 줄일 수 있는 무손실 스너버 적용 영전압, 영전류 스위칭 Forward 컨버터에 관한 것이다.

• 전력전자학회논문지
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• 제18권5호
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• pp.492-500
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• 2013

A balanced forward-flyback converter for high efficiency and high power factor using a foward and flyback converter topologies is proposed in this paper. The conventional AC/DC flyback converter can achieve a good power factor but it has the high offset current through the transformer magnetizing inductor, which results in a large core loss and low power conversion efficiency. And, the conventional forward converter can achieve the good power conversion efficiency with the aid of the low core loss but the input current dead zone near zero cross AC input voltage deteriorates the power factor. On the other hand, since the proposed converter can operate as the forward and flyback converters during switch turn-on and turn-off periods, respectively, it cannot only perform the power transfer during an entire switching period but also achieve the high power factor due to the flyback operation. Moreover, since the current balanced capacitor can minimize the offset current through the transformer magnetizing inductor regardless of the AC input voltage, the core loss and volume of the transformer can be minimized. Therefore, the proposed converter features a high efficiency and high power factor. To confirm the validity of the proposed converter, theoretical analysis and experimental results from a prototype of 24W LED driver are presented.

• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.197-204
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• 2014

In this paper an Improved Zero Voltage Zero Current Pulse Width Modulation Forward converter which employs a simple resonance snubber circuit is introduced. A simple snubber circuit consists of a capacitor, an inductor and two diodes. In proposed converter, switch Q1 operates at ZCS turn-on, and ZVS turn-off conditions and all-passive semiconductor devices operate at ZVZCS turn-on and turn-off state. The proposed converter is analyzed and various operating modes of the ZVZCS-PWM forward converter are discussed. Analysis and design considerations are presented and the prototype experimental results of a 100w (40 V/2.5A) proposed converter operating at 30 KHz switching frequency confirm the validity of theoretical analysis.

• 전력전자학회논문지
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• 제10권3호
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• pp.302-311
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• 2005

본 논문에서는 액티브 클램프 포워드컨버터 2차 측에 탭-인덕터와 스너버 커페시터, 두 개의 다이오드로 구성된 무손실 스너버를 적용한 개선된 액티브클램프 포워드컨버터를 제안하였고, 종래의 컨버터와 비교하여 제안된 컨버터가 보다 적은 자화전류조건에서도 영전압 스위칭(ZVS)이 가능함을 보였다. 제안된 컨버터의 동작원리 및 모드를 분석하였고, 300W출력용량의 컨버터 시제품을 제작 실험하여 제안된 컨버터의 효율특성이 개선됨을 보였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.636-641
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• 1998

In this paper, operation characteristics of the Zero-voltage-Switching(ZVS) mode and Non-Zero-Voltage-Switching (NZVS) mode of the active clamp (ACL) forward converter are compared through the loss analysis. The losses of semiconductor devices, transformer and passive elements of the converter are analyzed and compared for each type of operation mode. In order to verify the validity of the analysis, we have built a 50W ACL forward converter and measured the losses of the converter. From the experiment it is known that the ACL forward converter shows nearly same loss distribution for both of operation modes

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1232-1234
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• 2003

The push pull forward converter is a very suitable circuit for low output voltage, high output current applications with a wide input voltage range. This converter can be miniaturized by integrate magnetic components such as the output inductor, the transformer and the input inductor. We considered of the efficiency for the push pull forward converter. Developed the push pull forward converter rating are of $36{\sim}72V$ input and 3.3V/30A output. In this converter. the efficiency was measured by 76.4% at full load and 82.95% at half load. The maximum efficiency is up to 83.% at 200kHz, 11A output.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.64-65
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• 2008

The topology of active clamp forward converter provides ZVS characteristic and also the stress of voltage and current is smaller than that of the conventional forward converters. The benefits of this technique include a higher efficiency at a high switching frequency, lower EMI/RFI. In this paper, the active clamp forward converter is designed for operation in wide range voltage and has 19.5V/120W ratings with efficiency more than 90%.

• 조명전기설비학회논문지
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• 제12권4호
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• pp.90-99
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• 1998

DC/DC 컨버터의 리액티브 성분의 물리적 크기를 저감하고 동특성을 개선하기 위해서는 동작 스위칭 주파수 를 증가시키는 것이 바람직하다. 그러나 이것은 발열 및 스트레스로 인한 파워 소자의 파괴, 스위칭 손실 증가 로 인한 효율 감소 및 EM! 동의 문제가 발생한다. 따라서, 본 논문에서는 이러한 문제점을 해결하기 위해 보조 회로를 웅용한 소프트 스위칭 Forward-Flyback PWM DC/DC 컨버터를 제안하였다. 시뮬레이션 및 실험 결과로부터 제안한 컨버터의 타당성을 확인하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.614-617
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• 1999

To achieve high efficiency in high power and high frequency applications, reduction of switching losses and noise is very important. In this paper, an improved zero voltage switching forward dc/dc converter is proposed. The proposed converter is constructed by using energy recovery snubbers in parallel with the main switches and output diodes of the conventional forward dc/dc converter. Due to the use of the energy recovery snubbers in the primary and secondary side, the proposed converter achieves zero-voltage-switching turn-off without switching losses for switching devices and output rectification diodes. The complete operating principles and experimental results will be presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.49-51
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• 1997

This paper deals with analysis of high frequency transformer for forward converter using the finite element method and circuit analysis. Finite element analysis considering magnetic nonlinearity of ferrite core and circuit analysis are utilized when converter switch(FET) is on and off, respectively. As a result, the primary current and load current of a forward converter are obtained under the various load conditions.