• Journal of Power Electronics
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• 제17권2호
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• pp.323-333
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• 2017

This paper proposes a model-based optimal control algorithm for the clamp switch of a zero-voltage switching (ZVS) bidirectional DC-DC converter. The bidirectional DC-DC converter (BDC) can accomplish the ZVS operation using the clamp switch. The minimum current for the ZVS operation is maintained, and the inductor current is separated from the input and output voltages by the clamp switch in this topology. The clamp switch can decrease the inductor current ripple, switching loss, and conduction loss of the system. Therefore, the optimal control of the clamp switch is significant to improve the efficiency of the system. This paper proposes a model-based optimal control algorithm using phase shift in a micro-controller unit. The proposed control algorithm is demonstrated by the results of PSIM simulations and an experiment conducted in a 1-kW ZVS BDC system.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.256-262
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• 2018

This study introduces a novel Soft Switching (SS) Pulse Width Modulated (PWM) AC-DC boost converter. In the proposed converter, the main switch is turned on with Zero Voltage Transition (ZVT) and turned off with Zero Current Transition (ZCT). The main diode is turned on with Zero Voltage Switching (ZVS) and turned off with Zero Current Switching (ZCS). The auxiliary switch is turned on and off with ZCS. All auxiliary semiconductor devices are turned on and off with SS. There is no extra current or voltage stress on the main semiconductor devices. The majority of switching energies are transferred to the output by auxiliary transformer. Thus, the current stress of auxiliary switch is significantly reduced. Besides, the proposed converter has simple structure and ease of control due to common ground. The theoretical analysis of the proposed converter is verified by a prototype with 100 kHz switching frequency and 500 W output power. Furthermore, the efficiency of the proposed converter is 98.9% at nominal output power.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제2B권4호
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• pp.183-190
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• 2002

This paper presents an improved Zero Voltage/Zero Current Switching (ZVZCS) commutation cell with minimum additional components, which provides soft switching at both turn-on and turn-off of main and auxiliary switches as well as diodes in a PWM DC/DC converter. The proposed soft-switching technique is suitable for not only minority, but also majority carrier semiconductor devices. The auxiliary switch of the proposed ZVZCS commutation cell is in parallel with the main switch, and therefore, the main switch and the diode are free of currentstress. The operation principles of the proposed ZVZCS commutation cell are theoretically analyzed using the PWM boost converter topology as an example. The validity of the PWM boost converter topology with the proposed ZVZCS commutation cell is verified through theoretical analysis, simulation and experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.946-949
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• 2001

This paper proposes a new zero-current switching (ZCS) pulse-width modulation (PWM) switch cell that has no additional conduction loss of the main switch. In this cell, the main switch and the auxiliary switch turn on and turn off under zero current condition. The diodes commutate softly and the reverse recovery problems are alleviated. The conduction loss and the current stress of the main switch are minimized, since the resonating current for the soft switching does not flow through the main switch. Based on the proposed ZCS PWM switch cell, a new family of dc to dc PWM converters is derived. The new family of ZCS PWM converters is suitable for the high power applications employing IGBTs. Among the new family of dc to dc PWM converters, a boost converter was taken as an example and has been analyzed. Design guidelines with a design example are described and verified by experimental results from the 2.5 kW prototype boost converter operating at 40kHz.

• Journal of Power Electronics
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• 제15권5호
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• pp.1200-1206
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• 2015

This paper proposes an actively clamped two-switch flyback converter. Compared to the conventional two-switch flyback converter, the proposed two-switch flyback converter operates with a wide duty cycle range. By using an active-clamp circuit, the proposed converter achieves zero-voltage switching for all of the power switches. Zero-current switching of an output diode is also achieved. Thus, compared with the conventional converter, the proposed converter realizes a higher efficiency with an extended duty cycle. The performance of the proposed converter is verified by the experimental results with use of a 1.0 kW prototype circuit.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 학술대회 논문집 전문대학교육위원
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• pp.38-40
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• 2002

In the case of conventional high frequency inverter, with damage of switch by surge voltage when switch gets into compulsion extinction by load accident and so on because reactor is connected by series to switch, or there was problem of conduction loss by reactor's resistivity component, Also, it has controversial point of that can not ignore conduction loss of switch in complete work kind action of soft switching. In this paper, as high frequency induction heating power supply, we propose half bridge type multi resonance soft switching high frequency inverter topology that can realize high amplitude operation of load current with controlling switch current by multiplex resonance, mitigating surge voltage when switch gets into compulsion extinction and to be complete operation of zero current switching by opposit parallel connected reactor to inverter switch. and do circuit analysis for choice of most suitable circuit parameter of circuit

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.217-219
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• 2005

This paper presents an improved ZCT (Zero-Current-Transition) PWM DC/DC Boost Converter without additional current stress and conduction loss on the main switch during the resonance period of the auxiliary cell. The auxiliary cell consists of a resonance inductor, a resonant capacitor, an auxiliary switch and the Zero-Current-Switching ranges of the main and the auxiliary switch of the proposed converters are entirely achieved by operating the auxiliary cell. Then Improved ZCT soft switching converter will be discussed. Therefore, the proposed converter has a high efficiency. To show the superiority of this converter is verified through the experiment with a 640W, 50kHz prototype converter.

• 전력전자학회논문지
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• 제23권6호
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• pp.397-402
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• 2018

In this study, a high-efficiency flyback converter that uses a soft-switching auxiliary circuit is proposed. The structure of the proposed converter adds an inductor, switch, diode, and capacitor to the conventional flyback converter. The switch in the auxiliary circuit and the main switch are turned on and off under soft-switching conditions. Therefore, the switching losses of the proposed flyback converter are considerably smaller than those of conventional flyback converters. The performance of the proposed flyback converter is validated by experiments on a 100 W single-output flyback converter prototype, and design guidelines are presented.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권12호
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• pp.632-640
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• 2003

In conventional Zero-Voltage-Transition(ZVT) PWM converters, zero-voltage turn-on and turn-off for main switch without increasing voltage/current stresses is achieved at a fixed frequency. The switching loss, stress, and noise, however, can't be minimized because they adopt auxiliary switches turned off under hard-switching condition. In this paper, new ZVS-PWM converters of which both active and passive switches are always operating with soft-switching condition are proposed. Therefore, the proposed ZVS-PWM converters are most suitable for avionics applications requiring high-power density. Breadboarded ZVS-PWM boost converters using power MOSFET are constructed to verify theoretical analysis.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권9호
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• pp.467-472
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• 2001

In conventional zero-current-switching(ZCS) PWM converters, zero-current turn-off for main switch without increasing voltage/current stresses is achieved at a fixed frequency. The switching loss, stress, and noise, however, can\`t be minimized because they adopt auxiliary switches turned off and main switches turned on under hard-switching condition. In this paper, new ZCS-PWM converters of which all switches are always operating with soft-switching condition are proposed. Therefore, the proposed ZCS-PWM converters are most suitable for systems requiring high-power density Breadboarded ZCS-PWM boost converters using power MOSFET are constructed to verify theoretical analysis.