• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1193-1195
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• 2000

In conventional zero-current-switching(ZCS) PWM converters, the switching loss, stress and noise can't be minimized because they adopt auxiliary switches operated in hard-switching. In this paper, new ZCS-PWM converters of which auxiliary switches always operate with soft-switching are proposed. Therefore, the proposed ZCS-PWM converters are most suitable for systems requiring high-power density. The characteristics of these converters are verified by results of simulation.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.266-269
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• 2000

This paper presents a novel single-stage unity power factor converter which features the reduced switching losses by zero-voltage switching and zero-current switching (ZVZCS). Hence the turn-on and turn-off losses of switches are sufficiently reduced. And the reduced conduction losses are achieved by the elimination of one leg of front-end rectifier. And low on-resistance MOSFETs (Synchronous Rectifier) are used in the rectifier at the secondary side of high frequency transformer instead of diodes. Theoretical analysis simulated results of a AC to DC 150W(5V, 30A) converter are presented.

• Journal of Power Electronics
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• 제9권4호
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• pp.623-630
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• 2009

This paper proposes a filter design guideline for grid-connected single-phase inverters. By analyzing the instantaneous voltage applied to the filter inductor, the switching ripple current through the filter inductor can be precisely calculated. Therefore, filter inductance can be designed accurately, which guaranties that the switching ripple current will be under the target value. The proposed filter design method is verified by experiment.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권1호
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• pp.47-54
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• 2004

A new high voltage DC power supply is proposed. The proposed power supply is constructed with several power converters connected in series. It is easy to obtain high DC voltage for the same structure of each power converter. The output DC power of the proposed power supply can be disconnected from the load within several hundred microseconds at the instant of a load short-circuit fault. The rising time of the output DC voltage is also as small as several hundred microseconds, and there is no overshoot of the voltage because all of the output filter capacitors keep undischarged state even in load short-circuit condition. Therefore, the proposed scheme is suitable for the protection of frequent output short-circuit and fast on/off switching of output DC voltage. The proposed power supply has improved features such as simple structure, high power factor, and reduced size and volume compared with the conventional schemes. The operating principle is described and the validity of the proposed scheme is proved through simulations and experiments.

• 한국전기전자재료학회논문지
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• 제25권3호
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• pp.170-175
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• 2012

Power MOSFET is develop in power savings, high efficiency, small size, high reliability, fast switching, low noise. Power MOSFET can be used high-speed switching transistors devices. Recently attention to the motor and the application of various technologies. Power MOSFET is devices the voltage-driven approach switching devices are design to handle on large power, power supplies, converters, motor controllers. In this paper, design the 600 V Planar type, and design the trench type for realization of low on-resistance. For both structures, by comparing and analyzing the results of the simulation and characterization.

• 한국정보통신학회논문지
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• 제18권8호
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• pp.1854-1860
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• 2014

본 논문에서 이동통신 중계기를 위한 에너지 절감방법에 대한 연구를 수행하였다. 현재 실제 현장에서 서비스하고 있는 DB(Dual Band)소형 중계기에 있는 SMPS(Switching Mode Power Supply)에 PFC(Power Factor Correction)를 추가하여 전력소모를 감소하였으며, 이를 실제 구현하여 검증함으로써 실증된 결과를 도출하였다. 실증결과 장비 1식당 약 38.9% 피상전력 개선효과를 확인하였으며, 이를 연간으로 환산해 보면 약 230.43kWh의 에너지 절감효과가 있다.

• Journal of Power Electronics
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• 제7권2호
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• pp.109-117
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• 2007

In this paper, a novel proposal for a utility-interactive three-phase soft commutation sinewave PWM power conditioner with an auxiliary active resonant DC-link snubber is developed for fuel cell and solar power generation systems. The prototype of this power conditioner consists of a PWM boost chopper cascaded three-phase power conditioner, a single two-switch auxiliary resonant DC-link snubber with two electrolytic capacitors incorporated into one leg of a three-phase V-connection inverter and a three-phase AC power source. The proposed cost-effective utility-interactive power conditioner implements a unique design and control system with a high-frequency soft switching sinewave PWM scheme for all system switches. The operating performance of the 10 kW experimental setup including waveform quality, EMI/RFI noises and actual efficiency characteristics of the proposed power conditioner are demonstrated on the basis of the measured data.

• Journal of Power Electronics
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• 제18권6호
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• pp.1729-1750
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• 2018

Voltage source inverters (VSIs) are widely used to drive induction motors in industry applications. The quality of output waveforms depends on the switching sequences used in pulse width modulation (PWM). In this work, all existing optimal space vector pulse width modulation (SVPWM) switching strategies are studied. The performance of existing SVPWM switching strategies is optimized to realize a tradeoff between quality of output waveforms and switching losses. This study generalizes the existing optimal switching sequences for total harmonic distortions (THDs) and switching losses for different modulation indexes and reference angles with a parameter called quality factor. This factor provides a common platform in which the THDs and switching losses of different SVPWM techniques can be compared. The optimal spatial distribution of each sequence is derived on the basis of the quality factor to minimize harmonic current distortions and switching losses in a sector; the result is the minimum ripple loss SVPWM (MRSLPWM). By employing the sequences from optimized switching maps, the proposed method can simultaneously reduce THDs and switching losses. Two hybrid SVPWM techniques are proposed to reduce line current distortions and switching losses in motor drives. The proposed hybrid SVPWM strategies are MRSLPWM 30 and MRSLPWM 90. With a low-cost PIC microcontroller (PIC18F452), the proposed hybrid SVPWM techniques and the quality of output waveforms are experimentally validated on a 2 kVA VSI based on a three-phase two-level insulated gate bipolar transistor.

• Journal of Power Electronics
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• 제15권3호
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• pp.602-609
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• 2015

In this paper, a zero current transition (ZCT) double-ended flyback converter is proposed. All of the switching elements act under soft switching conditions and the voltage stress of the main switches is limited to the input voltage due to the innate behavior of the double-ended flyback converter. Providing soft switching conditions and clamping the voltage stress improves the efficiency and electromagnetic compatibility (EMC). The Proposed converter is analyzed in detail and its operating modes are discussed in detail. Experimental results are presented to verify the theoretical predictions. Moreover, the conducted electromagnetic emissions of the proposed ZCT double-ended flyback converter are measured to show another merit of the proposed converter in addition to providing soft switching conditions. The measured electromagnetic interference (EMI) of the proposed converter demonstrates that its EMI is lower than the conventional double-ended flyback converter. Furthermore, two simple and cost effective EMI reduction methods are applied to satisfy the EMC standard.

• 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.