• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.172-175
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• 2005

Recently international regulations governing the amount of harmonic currents(e.g IEC 61000-3-2) became mandatory and active Power factor correction (PFC) pre-regulator circuit became inevitable for the AC/DC converters. Among these topologies, the boost topology represents an optimum solution for a PFC pre-regulation in a high power application. This paper propose improved ZVT(Zero Voltage Transition) AC/DC PFC Boost using the average current control employing a soft-switching technique of the auxiliary switch with a minimum number of components. The conventional ZVT PFC Boost Converter has a disadvantage that the auxiliary switch turns off hard, which influences the overall efficiency and the EMI problem. In this paper, an improved ZVT PFC Boost converter using active snubber is proposed to minimize the switching loss of the auxiliary. The prototype of 100kHz, 640W system was implemented to show the improved performance.

• Proceedings of the IEEK Conference
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• 2001.06e
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• pp.245-248
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• 2001

This paper is indicating the problems, which are the conduction loss on the high frequency transformer, the protection of rectification diode as the snubber loss and the stress of switching main devices, as be made high current and high speed in the phase-shift switching full-bridge DC-DC converter is used the power supply’s main circuit of high capacity. To improve those problems, in this paper, it is proposed that is the resonant circuit auxiliary can be reduced conduction losses and stabilized output control. And, it is constructed prototype of the power supply as the result of computer simulations.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.4
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• pp.398-403
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• 2012

This paper describes about the analysis of firing rebounding force exerted on the launching system supporting structure. The measured high pressure data at the launching tube is used as external force. The maximum firing rebounding force was occurred when the snubber of inner structure contacts the surface of wall in launching tube.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.4
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• pp.535-542
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• 1996

A zero voltage switching (ZVS) three level auxiliary resonant commutated pole inverter (ARCPI) is presented for high power GTO inverters. The concept of ARCP for two level inverter is extended to the three inverter. The proposed auxiliary commutation circuit consists of one resonant inductor and two bi-directional switches, which provides ZVS condition to the main devices without increasing device voltage or current stresses. The auxiliary device operates with zero current switching (ZCS) which enables use of the low cost thyristors. The proposed ARCPI can handle higher voltage and higher power (1-10MVA) comparing to the two level one. Operation and analysis of the ARCPI are illustrated and the features are compared o those of the snubber circuit incorporated three level inverter. Experimental results with 10kW, 4kHz prototype are presented to verify the principle of operation. (author). refs., figs., tab.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.141-143
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• 2007

기존 역률 개선용 부스트 컨버터는 주 스위치의 전도 및 차단 시 전압과 전류의 중첩에 따른 큰 스위칭 손실과 다이오드 역회복 특성에 의한 소자 발열 및 서지 전류 발생으로 인해 시스템 효율과 신뢰성 측면에서 심각한 문제점이 존재한다. 이러한 문제점을 개선하기 위하여 본 논문에서는 새로운 무손실 스너버를 제안하며, 제안된 회로의 분석을 수행하고, 600W급 시작품을 이용한 실험적 분석을 통해 그 우수성을 검증한다.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.289-292
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• 2007

The flyback converter is one of the most attractive isolated converters in small power applications because of its simple structure. However, it suffers from high device stress, large transformer size, and high voltage stress across switch and diode. To solve these problems a new cost-effective PWM single-switch isolated converter is proposed. The proposed converter has no output filter inductor, reduced voltage stress on the secondary devices, and reduced transformer size. Moreover, the switch turnoff loss is reduced and no dissipative snubber across the secondary diode is required. Therefore, it features a simple structure, low cost, and high efficiency. The operational principle and characteristics of proposed converter are presented compared with flyback converter and verified experimentally.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.237-239
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• 2017

The isolated boost DC-DC converter based on three switches in fuel cell applications is presented in this paper. The major advantages of the proposed converter are as follows: continuous input current; decrease one active switch and no use snubber circuit. The operating principles and analysis of the proposed converter have been discussed. A 400 W prototype has been tested in the laboratory to verify the performance of the proposed converter and a PID controller was used to clarify the DC output voltage at 400 V. The simulation and experimental results are shown to validate the theoretical analysis.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.608-611
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• 2001

This paper is indicating the problems, which are the conduction loss on the high frequency transformer, the protection of rectification diode as the snubber loss and the stress of switching main devices, as be made high current and high speed in the phase-shift switching full-bridge DC-DC converter is used the power supply's main circuit of high capacity. In this paper, to improve those problems, it is proposed that is the resonant circuit auxiliary can be reduced conduction losses and stabilized output control. And, it is constructed prototype of the power supply as the result of computer simulations.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.5
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• pp.453-459
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• 2001

In this paper, the loss analyses of two soft switching techniques for two-transistor forward converter are performed. The sums of snubber conduction and capacitive turn-on losses for two transistors are calculated to compare the losses of the two techniques. While the conventional soft switching technique shows the loss difference between two transistors, the proposed soft switching technique shows equal as well as lower losses In two transistors. Thus, it can be said that even thermal distribution and higher reliability can be obtained by the proposed soft switching technique.

• Journal of Power Electronics
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• v.8 no.2
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• pp.192-199
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• 2008

This paper is mainly concerned with a high frequency soft-switching PWM inverter suitable for consumer induction heating systems. The proposed system is composed of a soft switching chopper based boost PFC converter stage with passive snubber and phase shifted PWM controlled full bridge ZVZCS high frequency inverter stage. Its fundamental operating performances are illustrated and evaluated in the experimental results. Its effectiveness is substantially proved on the basis of the experimental results from a practical point of view.