• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권4호
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• pp.366-373
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• 2005

This paper presents two new circuit topologies of the dc busline side active resonant snubber assisted voltage source high frequency link soft switching PWM full-bridge dc-dc power converters acceptable for either utility ac 200V-rms or ac 400V-rms input grid. These high frequency switching dc-dc converters proposed in this paper are composed of a typical voltage source-fed full-bridge PWM inverter, high frequency transformer with center tap, high frequency diode rectifier with inductor input filter and dc busline side series switches with the aid of a dc busline parallel capacitive lossless snubber. All the active switches in the full-bridge arms as well as dc busline snubber can achieve ZCS turn-on and ZVS turn-off transition commutation with the aid of a transformer leakage inductive component and consequently the total switching power losses can be effectively reduced. So that, a high switching frequency operation of IGBTs in the voltage source full bridge inverter can be actually designed more than about 20 kHz. It is confirmed that the more the switching frequency of full-bridge soft switching inverter increases, the more soft switching PWM dc-dc converter with a high frequency transformer link has remarkable advantages for its power conversion efficiency and power density implementations as compared with the conventional hard switching PWM inverter type dc-dc power converter. The effectiveness of these new dc-dc power converter topologies can be proved to be more suitable for low voltage and large current dc-dc power supply as arc welding equipment from a practical point of view.

• 조명전기설비학회논문지
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• 제22권7호
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• pp.7-15
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• 2008

A single active capacitor snubber-assisted soft-switching sinewave pulse modulation utility-interactive power conditioner with a three-winding flyback high frequency transformer link and a bidirectional active power switch in its secondary side has been proposed. With the aid of the switched-capacitor quasi-resonant snubber cell, the high frequency switching devices in the primary side of the proposed DC-to-AC sinewave power inverter can be turned-off with ZVS commutation. In addition to this, the proposed power conditioner in the DCM can effectively take the advantages of ZCS turn-on commutation. Its output port is connected directly to the utility AC power source grid. At the end, the prototype of the proposed HF-UPC is built and tested in experiment. Its power conversion conditioning and processing circuit with a high frequency flyback transformer link is verified and the output sinewave current is qualified in accordance with the power quality guidelines of the utility AC interactive power systems.

• 전기전자학회논문지
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• 제13권4호
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• pp.82-88
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• 2009

본 논문에서는 새로운 고효율의 절연형 스텝 업-다운 DC/DC 초퍼에 대해 해석하였다. 일반적으로 고효율의 초퍼를 만들기 위해서는 전력변환기내에 사용된 반도체 스위칭 소자의 손실이 최소화 되어야 한다. 본 논문에서는 부분공진 회로를 초퍼에 추가하여 고효율을 실현시킨다. 제안한 초퍼에 사용된 제어용 스위칭 소자들은 부분공진기법에 의해 소프트 스위칭으로 동작하고, 이에 따른 제어용 스위칭 소자들은 전압과 전류의 스트레스 없이 동작한다. 그 결과 제안한 초퍼는 스위칭 손실의 저감에 의해 고효율로 구동한다. 그리고 제안한 초퍼는 펄스 변압기를 이용하여 입력단과 출력단을 절연시켜, 전기적 절연이 요구되는 전력변환기들에 적용되어 고효율의 전력변환시스템을 개발할 수 있는 장점이 부여된다. 제안한 절연형 스텝 업-다운 초퍼의 소프트 스위칭 동작과 시스템 효율은 다양한 시뮬레이션과 실험결과를 통해 그 타당성이 입증된다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.431-432
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• 2014

Recently, the demand of LED(light-emitting diode) lighting is gradually enlarged by governmental saveenergy policy, which the LED lighting has been established compulsorily in new buildings, public institutions, and residential installations etc.. The LED lighting is driven by SMPS (switching mode power supply). The SMPS requires high efficiency because the SMPS changes a commercial ac power source to low voltage dc power source. Harmonic components that occur in the conversion process of SMPS decrease system power factor and deal great damage in electric power system. To improve such problems, this paper proposes a SMPS of high efficiency. The switching devices in the proposed SMPS are operated by soft switching technique using a new quasi-resonant circuit. The input ac current waveform in the proposed SMPS becomes a quasi-sinusoidal waveform proportional to the magnitude of input ac voltage under constant switching frequency. As a result, the proposed SMPS obtains low switching power loss and high efficiency, and its input power factor is nearly in unity.

• 반도체디스플레이기술학회지
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• 제19권4호
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• pp.99-104
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• 2020

In this paper, efficiency and loss characteristics of GaN FET were reported by applying it into the QR flyback converter. In particular, for the comparison of efficiency characteristics, QR flyback converter experimental circuits with Si FET and with GaN FET were separately produced in 12W class. As a result of the experiment, the experimental circuit of the QR flyback converter using GaN FET reached a high efficiency of 90% or more when the load power was 2W or more, and the maximum efficiency was observed to be about 92%, and the maximum loss power was about 1.1W. Meanwhile, the efficiency of the experimental circuit with Si FET increased as the input voltage increased, and the maximum efficiency was observed to be about 82% when the load power was 9W or higher, and the maximum loss power was about 2.8W. From the results, it is estimated that that in the case of the experimental circuit applying the GaN FET switch, the power conversion efficiency was improved as the switching loss and conduction loss due to on-resistance were reduced, and the internal loss due to the synchronous rectifier was minimized. Consequently, it is concluded that the GaN FET is suitable for under 20W class power supply unit as a high efficiency power switch.

• 한국안광학회지
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• 제4권2호
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• pp.45-49
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• 1999

고리형 증폭 공진기를 이용하여 $LiIO_3$ 결정에서 최대 출력 35mW의 연속발진 레이저 다이오우드에 대한, 제2조화파(파장 397 nm)를 발생시켰다. 사용된 비선형 결정은 두께 5mm, 10mm의 $LiIO_3$로 광축에 대해 $43.21^{\circ}$ 각도로 절단된 것이며, 양면은 파장 794nm에 대해 AR코팅(anti-reflection coating)을 하였다. 공진기 안에 결정이 들어갔을 경우, 펌핑광에 대해 최적의 모드매칭(mode matching)이 이루어지는 곡률 거울간 거리의 적정조건을 찾아내었다. 고리형 증폭 공진기에 의한 펑핑광의 공진증폭(resonant enchancement)으로 제2조화파 변화효율을 향상시킬 수 있었으며, 결정으로부터의 산란광에 의한 역진모드(counter-propagation mode)를 이용하여 레이저 다이오드의 주파수를 고리형 증폭 공진기의 공진 주파수에 locking 시켰다. 공진증폭율은 결정이 없을 때 약 45배, 결정이 있을 때에는 결정의 투과 손실로 인하여 약 14배이었다. 펌프 레이저 출력에 대한 제2조화파의 출력을 측정하였고, 28mW의 입사 출력에 대해 두께 5mm와 10mm에서 각각 $1.5{\mu}W$와 $6.6{\mu}W$ 이상의 출력을 얻을 수 있었으며, 그에 해당하는 변환효율(conversion efficiency)은 각각 $(6.584{\pm}0.56){\times}10^{-3}$%, $(2.6{\pm}0.21){\times}10%{-2}$%이었다.

• 전력전자학회논문지
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• 제11권6호
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• pp.489-493
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• 2006

이 논문의 목표는 최적의 효율을 갖는 PLS 구동 인버터 회로를 설계하는 것이다. 일반적으로 펄스로 구동되는 PLS가 높은 광변환 효율을 갖는다고 알려져 있다. 낮은 듀티비의 펄스를 만들 수 있는 회로로는 E급 공진형 인버터와 세미브리지 인버터가 있다. 이 논문에서는 위의 두 회로의 손실을 분석한다. 손실분석을 확인하기 위해서 220V 380W 입력소비전력을 갖는 인버터 회로를 제작하고 시험하였다. 실험결과를 통해서 높은 효율의 PLS 시스템을 확인했다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.223-225
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• 2005

This paper presents a novel prototype of a current source resonant inverter using insulated gate bipolar transistors for driving a streamer reactor, streamer generation technology has been recognized as one of the best methods for water treatment, disinfection, industrial wastes utilization, and so on. However, some technological difficulties related to efficient streamer production have been significant problems restricting streamer usage in the industrial plants. Introduced in this paper is a pulse density modulated high frequency inverter for a plasma generate, which is developed with the aim to improve power conversion and control characteristics of the streamer reactor by using advances in power electronic technology. The developed system implements the feedforward control-based pulse density modulation control scheme with pulse width modulation feedback control strategy to compensate temperature and other environmental influences on streamer discharge.

• 반도체디스플레이기술학회지
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• 제17권3호
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• pp.21-26
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• 2018

In this paper, the switching characteristics of the active clamp type flyback converter, which is deemed suitable for the miniaturization of the external power supply for home appliance, were analyzed and the process of reducing the switching loss was explained. The active clamp type flyback converter operating in the DCM has confirmed that the surge voltage of the main switch does not occur and the turn-off / on loss of the switch do not occur in principle. Also, in the case of the switch for synchronous rectifier, it was showed that the switch current showed half-wave rectified sinusoidal characteristic, and the switching loss was reduced. The switching characteristics of the experimental results gathered from 120 W class prototype were compared with the theoretical waveform in the steady-state and it was confirmed that the power conversion efficiency of the active clamp type flyback converter was maintained high due to the reduction of the switching loss.

• 조명전기설비학회논문지
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• 제24권1호
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• pp.152-159
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• 2010

오늘날 산업이 발달함에 따라 산업현장에서는 높은 전력밀도와 전력변환 효율을 가진 전력변환장치를 요구하는 분야가 많아졌다. 현재 개발 중인 차세대 고속철도 역시 이러한 분야 중 하나로서 고효율 및 고성능 그리고 고밀도의 전력변환 장치가 필요하다. 본 논문에서는 차세대 고속철도에 사용 될 배터리 충전장치의 새로운 제어방식을 제안한다. 배터리 충전장치용 위상천이(PB;Phase shift) FB(Full-bridge) ZVZCS 컨버터는 크게 1차 측 보조회로를 갖는 방식과 2차 측 보조회로를 가지는 방식으로 분류할 수 있다. 전역통과필터를 사용한 PWM 스위칭기법은 2차 측에 공진회로를 갖는 ZVZCS 컨버터를 제어하기 위하여 제안되었다. 디지털 전역통과필터는 기존의 위상지연 IC 대신에 ATmega_128 마이크로컨트롤러에 의한 제어를 하였다. 제안된 토폴로지를 확인하기 위해 PSIM 소프트웨어를 사용하여 시뮬레이션하였고 1[kW] 축소모델을 제작하여 실험하였다.