• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.247-250
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• 2001

This paper presents a simple and cost effective circuit topology of single-ended type high frequency quasi-resonant PWM inverter using IGBTs, which can operate under wide soft switching operation range based on ZCS for main power switch as compared with a conventional active voltage-clamped ZVS-PWM high frequency quasi-resonant inverter developed previously. In principle, this new circuit topology can efficiently operate under a constant frequency PWM control-based power regulation scheme. In particular, it is noted that the zero current soft switching (ZCS) commutation can achieve for the main active power switch. On the other hand, the zero voltage soft switching (ZVS) commutation can also achieve for the auxiliary active power switch. The operating principle of this high-frequency Inverter treated here and its power regulation characteristics are illustrated on the basis of the simulation and feasible experimental results.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.573-576
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• 1999

본 논문은 다양한 분야에 적용이 가능한 고압 직류 전원장치를 개발에 관한 것이다. 개발된 이 장치는 soft switching 기술을 이용하여 인버터의 전력소자가 switching 때문에 발생하는 손실과 EMI를 감소시키기 위하여 영전압 스위칭(ZVS; Zero Voltage Switching) 방식을 채택하였다. 이러한 고주파 인버터의 구동방식을 단일 Chip 제어기로 쉽게 구현할 수 있는 영전압 스위칭 위상전이 제어 직렬 공진형(ZVS PSC-SRI; ZVS Phase Shifted Control Series Resonant Inverter)으로 선택하여 제어기의 신뢰도를 높였고 장치의 고효율화(90%이상) 확보와 장치의 소형화뿐만 아니라 실용화를 위한 저가격화를 절충할 수 있는 방법을 중점적으로 연구하였다. 본 논문에서 고주파 고압 직류 전원 장치의 구성 및 설계, ZVS PSC-SR 인버터의 설계 그리고 고주파 고압 변압기의 설계에 관한 내용을 자세히 설명하고 제작된 고주파 고압 전원장치의 실험결과 및 고찰을 기술한다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1999.11a
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• pp.189-194
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• 1999

This paper proposes a current-fed type high frequency inverter using a soft switching technology Zero-Voltage-Switching to reduce turn on and off loss at the switching. The analysis of the proposed circuit was described by using normalized parameter and operating characteristics have been evaluated as to switching frequency and parameters. The theoretical results are in good agreement with the experimental ones. In the future the proposed circuit is considered to be useful for induction heating applications.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.14-19
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• 1998

This paper has described about principle and form of proposed circuit made use of soft switching technology ZVS(Zero-Voltage-Switching) to reduce turn on and off loss at switching. also, the analysis of the proposed circuit has described by using normalized parameter and operating characteristics have been evaluated as to switching frequency and parameters. In addition, this paper proves the propriety of theoretical analysis in terms of the experiments.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1634-1644
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• 2016

In this paper, a current-fed two-inductor bi-directional DC/DC converter using resonance (CF-TIBCR) and its design method are proposed. The CF-TIBCR has characteristics of low current ripple and a high current rating because of two separated inductors. Also, it achieves zero voltage switching for all switches and zero current switching for switches of a low voltage stage by using the resonant tank. Besides, a voltage spike problem in conventional current-fed converters is solved without the need for an additional snubber or clamping circuits. As a result, the CF-TIBCR features high step-up and high efficiency. Since the proposed converter has difficulty achieving the soft-switching condition when the converter requires the low voltage transfer ratio, a method that varies the number of resonant cycles is adopted to extend the output voltage range with satisfying the soft-switching condition. The principles of the operation characteristics are presented with a theoretical analysis, and the proposed converter is verified through results of an experiment using a laboratory prototype.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.2
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• pp.131-137
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• 1999

New zero voltage switched(ZVS) converter in which main switch is switched at zero voltage is proposed. A resonant inductor of conventional ZVS PW converter is replaced to two small saturable inductors in order to reduce conduction loss of auxiliary switch. Therefore, the switching loss of main switch is very low, and conduction losses of the main and auxiliary switch are lowered. The ZVS and above characteristics are verified by experimental results for a 200 kHz operation.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.1
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• pp.64-73
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• 2001

This paper presents a Zero Voltage and Zero Current Switching (ZVZCS) 3-Level DC/DC converter. This converter overcomes the drawbacks presented by the conventional Zero Voltage Switching(ZVS) 3-Level converter, such as high circulating energy, severe parastic ringing on the rectifier diodes, and limited ZVS load range for the inner switches. The converter presented in this paper uses a phase shift control with a flying capacitor in the primary side to achieve ZVS for the outer switches. Additionally, the converter uses an energy recovery snubber to reset the primary current during the free-wheeling stage to achieve ZCS for the inner switches. The proposed converters are analyzed and verified on 6kW, 39kHz experimental prototype.

• Journal of Power Electronics
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• v.13 no.2
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• pp.177-185
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• 2013

This paper studies a soft switching DC/DC converter to achieve zero voltage switching (ZVS) for all switches under a wide range of load condition and input voltage. Two three-level PWM circuits with the same power switches are adopted to reduce the voltage stress of MOSFETs at $V_{in}/2$ and achieve load current sharing. Thus, the current stress and power rating of power semiconductors at the secondary side are reduced. The series-connected transformers are adopted in each three-level circuit. Each transformer can be operated as an inductor to smooth the output current or a transformer to achieve the electric isolation and power transfer from the input side to the output side. Therefore, no output inductor is needed at the secondary side. Two center-tapped rectifiers connected in parallel are used at the secondary side to achieve load current sharing. Due to the resonant behavior by the resonant inductance and resonant capacitance at the transition interval, all switches are turned on at ZVS. Experiments based on a 1kW prototype are provided to verify the performance of proposed converter.

• Journal of Power Electronics
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• v.18 no.4
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• pp.955-964
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• 2018

In this paper, an active capacitor-diode-switch (CDS) snubber is proposed for L-type current-fed isolated DC-DC converters. The proposed CDS-clamped converter has a number of advantages. It can achieve wide range zero-voltage switching (ZVS) on two switches, a continuous input current with a low ripple, a reduction of one active switch and high efficiency. The operating principles, analysis and parameter design guideline are presented. A 300 W prototype is built to test the proposed converter. Simulation and experimental results are shown at 30 V input voltage and 400 V output voltage.

• Journal of Power Electronics
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• v.3 no.3
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• pp.175-184
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• 2003

In this paper, a new control scheme of Class-E inverter for reducing the crest factor of electronic ballasts for fluorescent lamps using Pulse-Frequency-Modulation (PFM) is Introduced The lifetime of the lamps is guaranteed by decreasing the lamp crest factor and also voltage stress of the switch is significantly decreased by a new scheme although conventional Class-E Inverter is used In this paper. The proposed PFM control scheme didn't use any auxiliary circuit. The proposed control strategy is executed by feeding back the Input voltage, and the zero-voltage-switching (ZVS) is ensured by maintaining constant turn-off time of the switch Therefore, the control principles of proposed method are explained in detail and its validity is verified through several simulations and experimental results.