• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.950-951
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• 2006

This paper proposed a new driving method for the stable lighting of CDM lamps. To avoid the acoustic resonance in the proposed method, the inverter output voltage will be a low frequency rectangular waveform containing a sinusoidal voltage ripple with high frequency. Moreover, the realtime power control of the inverter can be achieved by the control of switching currents. To verify the validity of tile proposed method, a prototype set-up was build and the experimental results are presented in this paper.

• 조명전기설비학회논문지
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• 제21권4호
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• pp.61-72
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• 2007

This study proposed a high efficiency DC-DC converter with a new current doubler rectifier for fuel-cell systems for use with the Nexa(310-0027) PEMFC from the Ballard Co. The proposed high efficiency DC-DC converter for the fuel-cell system generated ZVS by applying partial resonance and using a phase shift PWM control method. Constantly switching frequency, loss of switching, peak current, and peak voltage were reduced by this system. In addition to this system, two inductors were attached to a rectifier circuit allowing it to be able to provide the direct current(DC) and DC voltage safely to a load with reduced ripple components. Also, by using the newly proposed current doubler rectifier, the high frequency DC-DC converter for the fuel cell system was capable of reaching a highest efficiency of 92[%] as compared to 88.3[%] efficiency in previous results, which means that efficiency increased 3.7[%]. The overall results were confirmed by a simulation and laboratory experiment.

• 전력전자학회논문지
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• 제7권5호
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• pp.490-498
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• 2002

본 논문에서는 전압형 PWM 컨버터의 교류 입력측 LCL 필터의 설계기법을 제안한다 기존의 전압형 PWM 컨버터에서 전원계통으로 흘러 들어가는 스위칭 고조파전류를 억제하기 위해 교류 입력측에 LCL 필터를 설치하는 것은 매우 경제적이고 효과적인 방법이다 필터 커패시터로 스위칭 고조파전류를 흡수하며 공진을 억제하기 위해 수동 댐핑 저항을 이용한다 UPS용의 LCL 필터 구조 PWM 컨버터의 설계예시를 보였으며 제안한 설계기법의 타당성을 입증하기 위해 PSIM을 이용한 시뮬레이션을 행하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.506-509
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• 2002

In this paper, a design method of LCL filter at the AC input side of a voltage source PWM converter is proposed. Effective method to prevent pollution of the utility caused by high frequency current ripple is to use a LCL filter instead of the L filter The C elements in the filter provide a low impedance path for the high frequency component, preventing them from entering the utility. A resistor in series with a capacitor is used for damping the resonance in the filter. The design examples are shown and the validity of the proposed design method is verified through the PSIM simulation.

• 전력전자학회논문지
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• 제13권2호
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• pp.79-87
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• 2008

연료전지의 낮고 변동폭이 큰 전압을 안정된 높은 전압으로 승압시키기 위하여 부스트 컨버터가 사용되고 있다. 전기적인 절연이 요구되지 않는 응용에서는 손실, 가격 및 부피 상승의 원인이 되는 고주파 변압기가 없는 무변압기형의 부스트 컨버터가 장점을 갖는다. 본 논문에서는 새로운 무변압기형 부스트 컨버터를 제안한다. 제안한 컨버터는 $6{\sim}8$배의 실제 사용가능 한 승압비를 가지며 입 출력 전류 리플이 매우 작아 연료전지 응용에 적합하다. 이에 대한 이론적 해석과 시뮬레이션 및 실험파형을 통해 타당성을 검증하였다.

• 한국정보통신학회논문지
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• 제13권5호
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• pp.922-930
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• 2009

유도 전동기를 전압 제어하기 위한 최적 PWM 스위칭 방법을 제시하려한다. 전압 인버터의 공간 벡터 변조 방식은 DC-버스 이용을 향상시키고 정류 손실을 감소시키기 때문에 디지털 구현의 경우 특히 선호하는 PWM 방법이다. 유도 전동기 전압 제어를 위한 최적 PWM 스위칭 방법은 제시한 최적 PWM 알고리즘을 사용하여 두 개의 활성 전압 벡터(active voltage vector)와 하나의 영 전압 벡터(zero voltage vector)로 구성하였다. 선택된 스위칭 순차 열은 변조 지수(modulation index)와 운송파(carrier wave) 주기의 함수로 정의 된다. 순차 열은 인버터 스위칭 손실과 전류 리플 값을 기준으로 사용하여 선택된다. 실험 결과 중 저 전력용으로 사용할 경우 스위칭 주파수를 증가시킴에 따라 고조파 왜곡이 감소하고 동특성이 좋아짐을 확인할 수 있었다.

• IEIE Transactions on Smart Processing and Computing
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• 제3권6호
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• pp.425-429
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• 2014

This paper proposes a DC-DC Buck-Converter with DT-CMOS (Dynamic Threshold-voltage MOSFET) Switch. The proposed circuit was evaluated and compared with a CMOS switch by both the circuit and device simulations. The DT-CMOS switch reduced the output ripple and the conduction loss through a low on-resistance. Overall, the proposed circuit showed excellent performance efficiency compared to the converter with conventional CMOS switch. The proposed circuit has switching frequency of 1.2MHz, 3.3V input voltage, 2.5V output voltage, and maximum current of 100mA. In addition, this paper proposes a SCP (Short Circuit Protection) circuit to ensure reliability.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
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• pp.188-189
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• 2007

Axial magnetic field was applied into the hollow anode of plasma torch for the purpose of extension of electrode lifetime. The average arc voltage increased because the arc column became longer, the arc voltage ripple frequency became low. The steady state of arc voltage was removed by applied magnetic filed. The lifetime of electrode was over 1000 hours which is 100 times longer than operation without magnetic field.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2003년도 학술대회논문집
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• pp.31-35
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• 2003

This paper presents a microprocessor controlled digital ballast for HID lamps, which gives intelligent features such as a precise power control, optimum ignition voltage and detection of end of life. Average current mode PFC is employed for reducing EMI and a universal input. Direct spread spectrum is done by applying 1 KHz triangular wave for removing acoustic resonance. This frequency modulation of 1 KHz gives also low EMI level and no ripple on lamp current. The microprocessor controls the voltage of DC-bus, the voltage of ignition pulses, the power of output and the bandwidth of spread spectrum. A 250W digital ballast is implemented with an efficiency of 93％ and a maximum EMI level of 55 ㏈${\mu}$V.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 추계학술대회 논문집 학회본부
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• pp.138-140
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• 1994

In this paper, a three-phase active power filter using voltage- source PWM converter is designed to eliminate the harmonics and compensate the reactive power in the ac side. The predictive current control method is adopted, which provides constant switching frequency and low current ripple but has inherently one sampling error between the command and the actual current. Here we propose the algorithm which corrects this delay time. The converter voltage obtained from this current control can be accomplished by the space vector modulation method at a voltage-type converter. All control sequences of active filter is executed by a DSP which is designed to calculate floating points at very hight speed. Finally, the validity of this filter using the predictive current control method is demonstrated through experimental results.