• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.512-515
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• 1994

This paper propose the high power factor and efficiency buck-boost AC-DC converter because the input current is made sinusoidal wave in single phase alternating current source. The proposed converter is able to minimize switching loss by the partial resonant switching which is for switching devices to operate the zero voltage switching (ZVS) or zero current switching(ZCS) without increasing their voltage and current stresses.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.1
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• pp.26-33
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• 2000

본 논문에서는 PWM ac-dc 컨버터의 출력직류전압 안정화를 위한 새로운 방식의 입력전류 제어기법에 대해 기술하였다. 제안한 방식의 전류제어 기법은 히스테리시스 전류제어기가 갖는 장점을 모드 갖고 있을 뿐 아니라 스위칭 손실도 최소화되는 특성을 갖는다. 기존의 히스테리시스 전류제어기와 다른 점은 PWM 컨버터 각 상 입력전류의 반주기 내에 1/3구간에서는 컨버터의 스위칭 소자가 PWM에 의한 스위칭이 이루어지지 않는다는 것이다. 더군다나 입력전류의 피크값 근처에서 스위칭이 발생하지 않으므로 한 주기 평균 스위칭 손실을 최소로 할 수 있다는 것이 특징이다. 이러한 동작 원리에 대한 설명과 제안한 방식의 특성을 해석하였으며 실험을 통하여 그 효용성을 입증하였다.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.139-142
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• 2004

Recently the PDP is the most remarkable media for a next generation display device. In this paper, we proposed the PDP dedicated AC-DC converter using quasi resonant method because the PDP has a lot of power dissipation so we need to develope. The proposed converter using one transformer has soft switching and a advantage to lower voltage stress in switch and also is predicted to have high power efficiency, we proposed the principles and theory using the zero voltage switching and verified the validity through a experiment.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.493-496
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• 1999

A new soft switching single stage AC-DC full bridge boost converter with unit input power factor and isolated output is presented in this paper. Due to the use of a non-dissipative snubber on the primary side, a single stage high-power factor isolated full bridge boost converter has a significant reduction of switching losses in the main switching devices. The non-dissipative snubber adopted in this study consists of a snubber capacitor Cr, a snubber inductor Lr, a fast recovery snubber diode Dr, and a commutation diode Dr, and a commutation diode Dp. This paper presents the complete operating principles, theoretical analysis and experimental results.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1432-1434
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• 2005

Single-stage converters are simpler and less expensive than convention two-stage converters. It can be a challenge, however, to design single-stage converters to satisfy certain key criteria such as input power factor, primary-side do bus voltage, and output voltage ripple. This is especially true for higher power single-stage AC/DC TTFC(Two-Transistor Forward Converter).

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.153-155
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• 2019

This paper proposes a two-phase interleaved bridgeless single-stage ac-dc converter with magnetic integration that can achieve CCM power factor correction without input current sensing. All switches achieve ZVS turn-on and all diodes achieve ZCS turn-on for the whole grid cycle. SDAB-based modulation strategy is applied which results in simple power control and wide range output voltage. A flux cancellation method to integrate the interleaved transformer is firstly proposed in this paper to reduce the core size and loss. Experimental results on a 1.7-kW, 50kHz prototype are given to verify the principle and advantages of the proposed ac-dc converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.1
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• pp.78-86
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• 2005

Recently, a fuel cell with low voltage and high current output characteristics is remarkable for new generation system. It needs both a dc-dc boost converter and dc-ac inverter to be used in fuel cell generation system. Therefore, this paper presents dc-dc active clamp current-fed half-bridge converter with ZVS for fuel cell generation system. The proposed converter has outstanding advantages over the conventional dc-dc converters with respect to high efficiency and high component utilization. The Fuel Cell generation system consist of active clamp current-fed half-bridge converter to boost the Fuel Cell(PEMFC) voltage(28∼43[Vdc]) to 380[Vdc]. A single phase full-bridge inverter is implemented to produce 220[Vac], 60[Hz] AC outputs.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.4
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• pp.366-373
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• 2005

This paper presents two new circuit topologies of the dc busline side active resonant snubber assisted voltage source high frequency link soft switching PWM full-bridge dc-dc power converters acceptable for either utility ac 200V-rms or ac 400V-rms input grid. These high frequency switching dc-dc converters proposed in this paper are composed of a typical voltage source-fed full-bridge PWM inverter, high frequency transformer with center tap, high frequency diode rectifier with inductor input filter and dc busline side series switches with the aid of a dc busline parallel capacitive lossless snubber. All the active switches in the full-bridge arms as well as dc busline snubber can achieve ZCS turn-on and ZVS turn-off transition commutation with the aid of a transformer leakage inductive component and consequently the total switching power losses can be effectively reduced. So that, a high switching frequency operation of IGBTs in the voltage source full bridge inverter can be actually designed more than about 20 kHz. It is confirmed that the more the switching frequency of full-bridge soft switching inverter increases, the more soft switching PWM dc-dc converter with a high frequency transformer link has remarkable advantages for its power conversion efficiency and power density implementations as compared with the conventional hard switching PWM inverter type dc-dc power converter. The effectiveness of these new dc-dc power converter topologies can be proved to be more suitable for low voltage and large current dc-dc power supply as arc welding equipment from a practical point of view.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.1-8
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• 1997

PWM(Pulse Width Modulation) 컨버터의 제어에 있어서, 입력전압의 왜곡을 고려하지 않을 경우, 시스템의 성능 저하를 초래하게 된다. 본 논문은 왜곡된 3상 입력전압이 PWM 컨버터에 미치는 영향을 분석하고, 성능을 개선하기 위한 제어기를 설계한다. 제안된 방식은 단위 역률을 만족시키면서, THD(Total Harmonic Distortion) 및 DC-link 전압의 저차 ripple을 감소시킨다.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.342-345
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• 1999

This paper describes a current regulated PWM boost type rectifier based on modified trapezoidal PWM. Each switch of a converter has no switching for one third period of a fundamental line current. Therefore, the switching loss of the proposed scheme is less than that of the hysteresis current controller. Operating principle is described and controller. Operating principle is described and simulations and experiments are carried out.