• Journal of Power Electronics
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• 제17권4호
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• pp.860-873
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• 2017

The present article reports an analysis and investigation of a direct AC-AC quasi-resonant converter. A bidirectional power device, whose switching frequency is lower than the frequency of the current passing through the load, is used for its realization. The zero voltage switching mode is described when zero voltage on the power device is available by measuring it with the control system. The continuous current in the resonant inductance by switching the power device at zero voltage is considered, and it is characterized by two sub-modes. A mathematical analysis of the processes has been made and comparative results from the computer simulation and experimental study have been brought. The converter can be used in a wide areas of power electronics: induction heating, wireless power transfer, AC-DC converters, etc.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.294-298
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• 2003

In this paper, the new zero-current-transition (ZCT) circuit cell is proposed. The main switch is turned-off under the zero current and zero voltage condition, and there is no additional current stress and voltage stress in, the main switch and the main diode. The Auxiliary switch is turned-off under the zero voltage condition, and the main diode is turned-on under the zero voltage condition, The resonant current required to obtain the ZCT is small and regenerated to the input voltage source. The operational principles of the boost converter integrated with the proposed ZCT circuit cell is analyzed theoretically and verified by the simulation and experimental result. Index terms - zero-current-transition (ZCT), zero-current- switching (ZCS), zero-voltage-switching (ZVS)

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.227-231
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• 2001

A new primary-side-assisted zero-voltage and zero-current switching (ZVZCS) three-level DC-DC converter with flying capacitor is proposed. The three-level converters are promising in high voltage applications, and ZVZCS is a very effective means for reducing switching losses. The proposed DC-DC converter uses only one auxiliary transformer and two diodes to obtain ZCS for the inner leg. It has a simple and robust structure, and offers soft-switching capability even in short-switching conditions. The proposed converter was verified by experiments in a 6KW prototype designed for communication applications and operating at 100kHz.

• 한국정보통신학회논문지
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• 제8권5호
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• pp.1068-1073
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• 2004

전원장치의 소형화 핵심기술인 반도체 스위칭 기술을 이용하여 5 V/500 mA급 트랜스리스형 파워모듈(transless type power module)을 설계하였다. 파워 모들은 강압형 chopper 방식을 이용하였으며, 스위칭회로, 제어회로, 전압검출회로, 그리고 정전압 회로 등으로 구성되어 었다. 본 연구에서 설계한 스위칭 파워모듈은 0.2 V의 load regulation, 0.1 V의 line regulation, 85 mVp-p의 output ripple 전압, 64.7 kHz의 스위칭 주파수, 최대 58% 정도의 효율을 나타내었으며, 신뢰성 및 EMC 평가항목을 만족하였다.

• Journal of Power Electronics
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• 제10권3호
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• pp.235-244
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• 2010

This paper presents a new isolated soft-switching bidirectional buck-boost inverter for fuel cell applications. The buck-boost inverter combines an isolated DC-DC converter with a conventional inverter to implement buck-boost DC-DC and DC-AC conversion. The main switches achieve zero voltage switching and zero current switching by using a novel synchronous switching SVPWM and the volume of the transformer in the forward and fly-back mode is also minimized. This inverter is suitable for wide input voltage applications due to its high efficiency under all conditions. An active clamping circuit reduces the switch's spike voltage and regenerates the energy stored in the leakage inductance of the transformer; therefore, the overall efficiency is improved. This paper presents the operating principle, a theoretical analysis and design guidelines. Simulation and experimental results have validated the characteristics of the buck-boost inverter.

• Journal of Power Electronics
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• 제13권1호
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• pp.40-50
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• 2013

In this paper, a new zero-voltage-switching, high power-factor, bridgeless rectifier is introduced. In this topology, an auxiliary circuit provides soft switching for all of the power semiconductor devices. Thus the switching losses are reduced and the highest efficiency can be achieved. The proposed converter has been analyzed and a design procedure has been introduced. The control circuit for the converter has also been developed. Based on the given approach, a 250 W, 400 Vdc prototype converters has been designed at 100 kHz for universal input voltage (90-264 Vrms) applications. A maximum efficiency of 94.6% and a power factor correction over 0.99 has been achieved. The simulation and experimental results confirm the design procedure and highlight the advantages of the proposed topology.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권9호
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• pp.444-449
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• 2005

This paper proposes the new soft switching DC-DC converter. We reported the experimental results of the new soft switching DC-DC converter. The proposed converter is to resonate between the leakage inductance of the transformer and the parasitic capacitances of the main switches for zero voltage switching. The voltage stresses of the two switches are the input voltage, it can improve the efficiency and a reduced height used two transformers. Theoretical analysis of the converter along with experimental results is provided. Finally, a 3.3V/20A prototype converter operation at 100kHz is built and experimental waveform verifies the analysis.

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1539-1548
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• 2018

This paper introduces a new soft switched AC-DC boost converter with power factor correction (PFC). In the introduced converter, all devices are turned on and off under soft switching (SS). The main switch is turned on under zero voltage transition (ZVT) and turned off under zero current transition (ZCT). The main diode is turned on under zero voltage switching (ZVS) and turned off under zero current switching (ZCS). Meanwhile, there is not any current or voltage stress on the main devices. Besides, the auxiliary switch is turned on under ZCS and turned off under ZVS. The detailed theoretical analysis of the converter is presented, and also theoretical analysis is verified by a prototype with 100 kHz and 500 W. Also, the proposed converter has 99.8% power factor and 97.5% total efficiency at soft switching operation.

• Journal of Power Electronics
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• 제12권5호
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• pp.723-730
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• 2012

This paper presents a new ZVS single phase bridgeless (Power Factor Correction) PFC, using an active clamp to achieve zero-voltage-switching for all main switches and diodes. Since the presented PFC uses a bridgeless rectifier, most of the time, only two semiconductor components are in the main current path, instead of three in conventional single-switch configurations. This property significantly reduces the conduction losses,. Moreover, zero voltage switching removes switching loss of all main switches and diodes. Also, auxiliary switch turns on zero current condition. The presented converter needs just a simple non-isolated gate drive circuitry to drive all switches. The eight stages of each switching period and the design considerations and a control strategy are explained. Finally, the converter operation is verified by simulation and experimental results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 추계학술대회 논문집
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• pp.227-230
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• 2002

The switching device in an inductive circuit is stressed by the over-voltage at the turn-off time. Thus if the peak value of the over-voltage is not properly limited, the switching device may be broken. Therefore, the snubber circuit should be added to protect the switching device from the over-voltage. The circuit designer must be familiar with the design of the snubber This paper tests the possibility that TVS instead of the conventional snubber can be applied to the protection circuit of the switching device without using the complicated design equations, and shows that the rating of TVS can be easily selected by considering only several parameters of TVS. The experimental results show the reduced switching voltage of the switching device at the turn-off time.