• 전력전자학회논문지
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• 제7권2호
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• pp.129-136
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• 2002

최근에 전력계통의 안정 및 고품질화에 대한 요구가 증대되기 시작하였고, 이에 따라 향상된 전력변환기술과 대체에너지원을 이용한 계통연계형 시스템에 대한 연구가 활발히 진행되고 있다 이러한 시스템에서의 인버터의 효율은 매우 중요하다. 따라서 본 논문에서는 이러한 계통연계형 시스템을 고효율화 하기 위한 방법으로 소프트-스위칭 기법이 적용 가능한 전류제어형 인버터를 제안하였다. 또한, 소프트-스위칭 기법을 적용할 수 있는 전류제어 알고리즘과 ZVT 동작원리를 이론적으로 해석하였고 이의 유용성을 시뮬레이션과 실험을 통하여 입증하였다.

• 전력전자학회논문지
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• 제18권6호
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• pp.547-555
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• 2013

This paper proposes the interleaved buck converter using a soft switching auxiliary circuit. In this scheme, an auxiliary circuit is added to the conventional interleaved buck converter and used to achieve soft-switching conditions for both the main switch and freewheeling diode. In addition, the switch in the auxiliary circuit operates under soft-switching conditions. Also, according to the input to output conditions, the main switch achieved zero-current-transition(ZCT) or zero-current & zero-voltage-transition(ZCZVT) at turn on. Thus, the proposed interleaved buck converter provides a higher efficiency. The basic operations, in this paper, are discussed and design guidelines are presented. The usefulness of the proposed converter is verified on a 200kHz, 180W prototype converter.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.759-762
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• 2002

A ZCT(Zero Current Transition) PWM(Pulse-Width-Modulation) boost converter using parallel MOSFET switch is proposed in this paper. The IGBT(main switch) of the proposed converter is always turned on with zero current switching and turned off with zero current/zero voltage switching. The MOSFET(auxiliary switch) is also operates with soft switching condition. In addtion to, the proposed converter eliminates the reverse recovery current of the freewheeling diode by adding the resonant inductor, Lr, in series with the main switch. Therefore, the turn on/turn off switching losses of switches are minimized and the conduction losses by using IGBT switch are reduced. In addition to, using parallel MOSFET switch overcomes the switching frequency limitation occurred by current tail. As mentioned above, the characteristics are verified through experimental results.

• 전기학회논문지P
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• 제57권2호
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• pp.72-78
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• 2008

The speed variation of SRM is fulfilled throughout a transition from chopping control to single pulse operation. (i,e., low speed to high speed operation). It is unsatisfied with performance at all operational regimes. In this paper, the operational performance of SRM can be improved by using current hysteresis control method. This method maintains a generally flat current waveform. At the high speed, the current chopping capability is lost due to the development of the back-EMF. Therefore SRM operates in single pulse mode. By using zero-current switching and zero-voltage switching technique, the stress of power switches can be reduce in chopping mode. When the commutation from one phase winding to another phase winding, the current can be zero as fast as possible in this period because several times negative voltage of DC-source voltage produce in phase winding. This paper is compared to performance based on conventional C-dump converter topology and the proposed resonant C-dump converter topology. Simulation and experimental results are presented to verify the effectiveness of the proposed circuit.

• 조명전기설비학회논문지
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• 제19권8호
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• pp.62-69
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• 2005

본 논문에서는 보조 스위치의 하드 스위칭 문제를 개선한 AC/DC PFC(Power-Factor-Correction) ZVT(Zero-Voltage-Transition) Boost 컨버터에 관하여 논하였다. 기존의 AC/DC PFC ZVT Boost 컨버터는 주 스위치 턴온 시 보조 스위치를 함께 동작시켜 경부하시에도 강제적으로 영전압 스위칭이 가능하게 함으로써 전 부하범위에서 주 스위치 손실을 저감하였다. 그러나 보조 스위치에서의 손실이 크며 주 스위치의 턴온시 역방향 전류가 증가하는 문제점을 지닌다. 따라서 본 연구에서는 기존의 ZVT 컨버터에 단지 하나의 다이오드를 추가함으로써 보조 스위치의 전류 스트레스 및 주 스위치의 턴온시 역방향 전류를 감소시키게 되어 효율 향상을 기할 수 있었다. 본 논문에서는 MOSFET를 사용하여 640[W]급 시작품을 제작, 100[kHz]에서 실험하였다.

• Journal of Power Electronics
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• 제11권1호
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• pp.1-9
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• 2011

This paper describes a two quadrant bidirectional soft switching converter for ultra capacitor interface circuits. The total efficiency of the energy storage system in terms of size and cost can be increased by a combination of batteries and ultra capacitors. The required system energy is provided by a battery, while an ultra capacitor is used at high load power pulses. The ultra capacitor voltage changes during charge and discharge modes, therefore an interface circuit is required between the ultra capacitor and the battery. This interface circuit must have good efficiency while providing bidirectional power conversion to capture energy from regenerative braking, downhill driving and the protecting ultra capacitor from immediate discharge. In this paper a fully soft switched two quadrant bidirectional soft switching converter for ultra capacitor interface circuits is introduced and the elements of the converter are reduced considerably. In this paper, zero voltage transient (ZVT) and zero current transient (ZCT) techniques are applied to increase efficiency. The proposed converter acts as a ZCT Buck to charge the ultra capacitor. On the other hand, it acts as a ZVT Boost to discharge the ultra capacitor. A laboratory prototype converter is designed and realized for hybrid vehicle applications. The experimental results presented confirm the theoretical and simulation results.

• Journal of Power Electronics
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• 제19권4호
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• pp.846-857
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• 2019

Voltage step-down converters are very popular in distributed power systems, voltage regular modules, electric vehicles, etc. However, a high step-down voltage ratio is required in many applications to prevent the traditional buck converter from operating at extreme duty cycles. In this paper, a series capacitor interleaved buck converter with a soft switching technique is proposed. The DC voltage ratio of the proposed converter is half that of the traditional buck converter and the voltage stress across the one main switch and the diodes is reduced. Moreover, by paralleling the series connected auxiliary switch and the auxiliary inductor with the main inductor, zero voltage transition (ZVT) of the main switches can be obtained without increasing the voltage or current stress of the main power switches. In addition, zero current turned-on and zero current switching (ZCS) of the auxiliary switches can be achieved. Furthermore, owing to the presence of the auxiliary inductor, the turned-off rate of the output diodes can be limited and the reverse-recovery switching losses of the diodes can be reduced. Thus, the efficiency of the proposed converter can be improved. The DC voltage gain ratio, soft switching conditions and a design guideline for the critical parameters are given in this paper. A loss analysis of the proposed converter is shown to demonstrate its advantages over traditional converter topologies. Finally, experimental results obtained from a 100V/10V prototype are presented to verify the analysis of the proposed converter.

• 전력전자학회논문지
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• 제18권4호
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• pp.359-366
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• 2013

This paper proposes a zero-current-transition(ZCT) synchronous buck converter using auxiliary circuit with soft-switching for light weight and high efficiency. In this scheme, an auxiliary circuit is added to the conventional synchronous rectifier buck converter and used to achieve soft-switching condition for both the main switch and synchronous switch. In addition, the switch in the auxiliary circuit operates under soft-switching conditions. Thus, the proposed converter provides a higher efficiency. The basic operations, in this paper, are discussed and design guidelines are presented. The usefulness of the proposed converter is verified on a 200KHz, 20 W prototype converter.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.694-700
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• 1998

A novel zero-voltage-transition (ZVT) isolated PWM boost converter for single stage power factor correction (PFC) is presented to improve the performance of the previously presented ZVT converter[8]. A simple auxiliary circuit which includes only one active switch provides zero-voltage-switching (ZVS) condition to all semiconductor devices. (Two active switches are required for the previous ZVT converter) This leads to reduced cost and simplified control circuit comparing to the previous ZVT converter. The ZVS is achieved for wide line and load ranges with minimum device voltage and current stresses. Operation principle, control strategy and features of the proposed converter are presented and verified by the experimental results from a 1.5 kW, 100 KHz laboratory prototype.

• Journal of Power Electronics
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• 제16권1호
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• pp.74-83
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• 2016

A new family of zero-voltage-transition converters with synchronous rectification is introduced in this study. Soft switching condition for all the converter operating points is provided in the proposed converters. The reverse recovery losses of the rectifier switch body diode are also eliminated. In comparison with the main switch voltage stress, the auxiliary switch voltage stress is reduced significantly. The auxiliary switch does not need the floating gate drive. The auxiliary inductor is coupled with the main converter inductor, and the leakage inductor is used as the resonance inductor. Thus, all inductors of the proposed converter can be implemented on a single core. The other features of the proposed converters include no extra voltage and current stresses on the main converter semiconductor elements. Theoretical analysis for a synchronous buck converter is presented in detail, and the validity of the theoretical analysis is justified with the experimental results of a prototype buck converter with 180 W and 80 V to 30 V.