• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
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• pp.87-91
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• 2004

In this paper, the paralleled forward converter, that is generally used as the power supply for the low voltage, high current load, is described. The proposed forward converter for battery charging could be provided the power without failure not only in steady state but also in the transient period by the step load variation or the unexpected faults among the converter modules. Each converter nodule designed is operated alone with the self closed controller for the elevation of stability, performance, reliability, and maintainability. The frequency response of the designed converter module is analyzed, and the stability is confirmed in analytic method. And the experiments of the paralleled battery charger are carried out in steady state, in the step load variation.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.505-507
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• 2008

A conventional active-clamp forward (ACF) converter is a favorable candidate in low-to-medium power applications. However, the switches suffer from high voltage stress, i.e., sum of the input voltage and the reset capacitor voltage. Therefore, it is not suitable for high input voltage applications such as a front-end converter of which the input voltage is about 400-$V_{dc}$. To solve this problem, three-switch ACF (TS-ACF) converter, which employs two main switches and one auxiliary switch with low voltage stress, is proposed. Utilizing low-voltage rated switches, the proposed converter is promising for high input voltage applications with high efficiency and low cost.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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• pp.147-149
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• 1998

In this paper, zero voltage switched half bridge converter and an active-clamped, zero voltage switched forward converter equipped with self-driven synchronous rectifier is designed and investigated for high efficiency BC-DC converter. A synchronous rectifier is has a lower conduction power loss than shottky diode rectifier. The purpose of this paper is to investigate the effect of parasitic inductance in a synchronous rectifier of DC-DC converters and examine overall efficiency of zero voltage switched DC-DC converters.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.418-422
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• 1998

A new single stage AC/DC converter based on the forward converter is proposed. The proposed converter offers both the high power factor and the direct conversion from ac line to dc output voltage. Also, the proposed converter reduces the diode conduction loss, so improves the overall efficiency of the converter, compared with other alternatives. The principles of operation and the simulation results of the proposed converter are presented. A 100 W prototype was built and tested to show the potential of applications of the proposed converter.

• 조명전기설비학회논문지
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• 제16권5호
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• pp.7-13
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• 2002

고효율 고전력 밀도를 제공하는 공진형 컨버터에 있어서 스위치에 걸리는 전압 스트레스는 입력전압의 4∼5배 정도여서, 높은 정격의 소자를 필요로 하기 때문에 전도손실을 증가시킨다. 본 논문에서는 이러한 문제점을 해결하기 위해 제안했던 교번으로 동작하는 포워드 다중공진형 컨버터에 적용한 회로 형태를 다른 컨버터에 적용한 예를 제시하였다. 그리고 제안한 AT포워드 다중공진형 컨버터의 루프 이득 특성을 알아보기 위해 HP4194A 네트워크 해석기를 이용해 실험적으로 측정한 결과에 대해 고찰하였다.

• Journal of Power Electronics
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• 제13권5호
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• pp.757-765
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• 2013

For conventional interleaved two-phase forward converters with a common output inductor, the maximum duty cycle is 0.5, which limits the voltage range and increases the difficulty of the transformer's optimization. A new two-phase hybrid forward converter with series-parallel auto-regulated transformer windings is presented in this paper. With interleaved control signals for the two phases, the secondary windings of the transformers can work in series when the duty cycle is larger than 0.5, and they can work in parallel when duty cycle is lower than 0.5. Therefore, the maximum duty cycle is extended and the turns ratio of the transformer can be optimized. Duty cycle dependent auto-regulated windings result in the steady states of the converter being different in different duty cycle ranges (D>0.5 and D<0.5). Fortunately, the steady state gains of the proposed hybrid converter are identical at different duty cycle ranges, which means a stepless shift between two states. A prototype is built to verify the theoretical analysis. A conventional control loop is compatible for the whole input voltage range and load range thanks to the stepless shifting between the different duty cycle ranges.

• Journal of Power Electronics
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• 제19권4호
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• pp.1011-1019
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• 2019

In this paper, a buck-flyback (fly-buck) stand-alone photovoltaic (PV) system for charge balancing with a differential power processor (DPP) circuit is proposed. Conventional feed-back DPP converters draw differential feed-back power from the output of a string converter. Therefore, the power is always through the switches and diodes of the string converter. Because of the returning conduction path, there are always power losses due to the resistance of the switch and the forward voltage of the diode. Meanwhile, the proposed feed-back DPP converter draws power from the magnetically-coupled inductor in a string converter. This shortens the power path of the DPP converter, which reduces the power losses. In addition, the extra winding in the magnetically-coupled inductor works as a charge balancer for battery-stacked stand-alone PV systems. The proposed system, which uses a single magnetically-coupled inductor, can control each of the PV modules independently to track the maximum power point. Thus, it can overcome the power loss due to the power path. It can also achieve charge balancing for each of the battery modules. The proposed topology is analyzed and verified using 120W hardware experiments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.247-250
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• 2006

This paper presents the single-stage High Power Factor TSFC(Two-Switch Forward Converter). Recently, due to growing concern about the harmonic pollution of power distribution systems and the adoption of standards such as ICE 61000-3-2 and IEEE 519, There is a need to reduce the harmonic contents of AC line currents of power supplies. This research proposed the single-stage two switch forward circuit for low voltage and high current output. The principle of operation, feature and design considerations are illustrated and verified through the experiment with a 200W(5V, 40A) 200kHz MOSFET based experimental circuit.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.169-172
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• 2006

This paper presents the single-stage High Power Factor AC/DC Two-Switch Forward Converter (TSFC). Recently, due to growing concern about the harmonic pollution of power distribution systems and the adoption of standards such as ICE 61000-3-2 and IEEE 519, There is a need to reduce the harmonic contents of AC line currents of power supplies. This research proposed the single-stage two switch forward circuit for low voltage and high current output. The principle of operation, feature and design considerations are illustrated and verified through the simulation with a 200W(5V, 40A) 200kHz MOSFET based experimental circuit.

• 조명전기설비학회논문지
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• 제12권3호
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• pp.37-44
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• 1998

본 논문에서는 분산전원 장치에 사용되는 증첩형 액티브클램프 ZVS 포워드 컨버터와 ZVS 하프 브리지(Half bbridge) 컨버터의 동작특성과 효율을 비교하였다. 또한 중첩형 액티브클램프 ZVS 포워드 컨버터의 전류모드 제어회로 설계 방법을 제시하였고, 게이트 구동회로를 간단히 하기 위해 N-P M OSFETs 로 조합된 액티브클램프 기법을 제안하여 50~100% 부하 범위에서 약 90%의 효율을 얻을 수 있었다.