• 전력전자학회논문지
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• 제22권4호
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• pp.277-284
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• 2017

For passive power factor correction, the valley fill circuit approach is attractive for low power applications because of low cost, high efficiency, and simple circuit design. However, to vouch for the product quality, two dc-link capacitors in the valley fill circuit should be selected to withstand the peak rectified ac input voltage. The common mode (CM) and differential mode (DM) choke should be used to suppress the electromagnetic interference (EMI) noise, thereby resulting in large size volume product. This paper presents the practical design and implementation of a valley fill flyback converter with reduced dc link capacitors and EMI magnetic volumes. By using the proposed over voltage protection circuit, dc-link capacitors in the valley fill circuit can be selected to withstand half the peak rectified ac input voltage, and the proposed CM/DM choke can be successfully adopted. The proposed circuit effectiveness is shown by simulation and experimentally verified by a 78W prototype.

• 산업기술연구
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• 제31권A호
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• pp.103-107
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• 2011

In this paper, a method is proposed to improve power factor and the input current THD in LED driver circuit. The researched circuit consists of a valley-fill circuit and boosting inductor and a Buck converter. Valley-fill circuit is a passive PFC and simplified structure, the buck converter is operated with current feedback. The switching frequency is 50KHz in LED driver circuit and LED forward current is constant. A valley-fill type PFC circuit for LED driver(15Watt) has been implemented, and the validity of proposed method is shown by is simulation and experimental result.

• 조명전기설비학회논문지
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• 제22권1호
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• pp.87-94
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• 2008

본 연구는 밸리-필 정류기를 이용한 전류 THD 개선 방법을 제시한다. 제안된 회로는 밸리-필 정류기와 부스팅 인덕터를 결합한 구조를 가지며, AC/DC 변환과 PFC를 동시에 수행한다. PWM 스위칭에 따른 부스팅 효과로 입력전류를 제어하여 밸리-필 정류기의 특성을 개선한다. 이 결과는 낮은 전류 THD를 보장한다. 동작 모드와 전류 THD를 분석하고, 최적 부스팅 인덕터를 결정한다. 밸리-필 정류기와 부스팅 인덕터를 채용한 100[W] AC/DC 컨버터를 제작하였고, 시뮬레이션과 실험으로 제안된 방법의 타당성을 검증하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2935-2938
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• 2003

A new Valley-fill circuit for improving PF(power factor) is proposed in this paper. The proposed topology combines Valley-fill rectifier and an additional inductor for boosting. In the proposed circuit, a shapc of input current is related to the PWM duty cycle. The boosting inductor makes improve PF by the electric charge transfer action. The operation principle and the shape of input current arc analyzed as applied the boosting inductor. The optimum value of boosting inductor is determined. A 100W single-stage converter has been designed and tested. Experimental results are presented to verify the validity of the proposed converter.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2002-2006
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• 1997

A new PF correction topology, Improved Valley Fill (IVF) with Valley Boost Converter (VBC) used in the electronic ballast for fluorescent lamp is presented. The IVF can adjust the valley voltage higher than half the peak line voltage. Hence, there is no pulsating line current around the line voltage peak, PF and THD are significantly improved. The VBC is added to the IVF to achieve unity PF and to increase the valley voltage. The measured PF and THD for a prototype electronic ballast are 0.997 and 5%, respectively, and the lamp current CF is as low as 1.5

• 산업기술연구
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• 제32권A호
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• pp.109-114
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• 2012

In this paper, We studied LED(Light Emitted Diode) sensor lights system using PIR(Pyroelectric Infrared Ray) sensor, CdS and MCU(Micro Controller Unit). And applied the valley fill circuit to improve the power factor. We designed the amplifier for each sensor and the LED driver for constant current which is the buck converter. Also, we proposed the algorithm of LED control by each sensors using MCU. Experimental results showed that power factor is 92% with valley fill circuit.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2798-2800
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• 1999

A new circuit, modified valley fill (MVF) combined with resonant inductor of the self-excited resonant inverter and charge pump capacitors(CPCs), is presented to achieve high PF electronic ballast providing sufficient preheat current to lamp filaments for soft start maintaining low DC bus voltage. The MVF can adjust the valley voltage higher than half the peak line voltage. The CPCs draw the current from the input line to make up the current waveform during the valley interval. The measured PF and THD are 0.99 and 12%, respectively. The lamp current CF is also acceptable in the proposed circuit. The proposed circuit is suitable for implementing cost-effective electronic ballast.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1361-1363
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• 2005

THD's effects on electronic ballast for fluorescent lamp and ways to improve. To design AC/DC converter in order to enhance current THD. valley-fill circuit and charge pump circuit which has improved valley-fill circuit.

• 전력전자학회논문지
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• 제19권4호
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• pp.297-302
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• 2014

In this paper, a LED driver compatible with TRIAC-dimmer applying active bleeder is proposed. If TRIAC-dimmer is connected with LED driver, flicker phenomenon occurs by TRIAC malfunction. In order to prevent this problem, a current over holding current must flow into TRIAC. Therefore, additional circuit compatible with TRIAC-dimmer is required to provide enough current. Passive bleeder has power loss in whole operation period. The proposed circuit apply a valley-fill circuit for power-factor-correction and a novel active bleeder detecting malfunction point of TRIAC. Therefore, it prevent malfunction of TRIAC-dimmer and have advantage of higher efficiency than passive bleeder. To verify the validity of proposed circuit, 13W-lighting LED driver prototype has been proposed.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 전력전자학술대회 논문집
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• pp.159-160
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• 2013

본 논문에서는 백열등 조도 조절용 조광기에 호환 가능한 LED 구동회로를 제안한다. 조광기와 일반적인 LED 구동회로를 연결할 경우 트라이악(Triac)의 오동작에 의해 플리커(Flicker) 현상이 발생하는 문제점을 지니고 있다. 트라이악의 오동작을 방지하기 위해서는 트라이악에 일정 크기 이상의 전류가 인가되어야 하며 이를 만족하기 위한 조광기 호환회로가 필수적이다. 이러한 호환회로로써 수동 블리더(Passive Bleeder)는 전 동작 구간에서 전력소모가 발생하는 단점을 지니고 있다. 본 논문의 제안회로는 역률 만족을 위 해 Valley-fill 회로를 적용하였으며 트라이악의 오동작 시점을 정확히 검출하여 새로운 방식의 능동 블리더(Active Bleeder)를 적용함으로써 조광기의 오동작을 방지하면서 수동 블리더에 비해 효율이 개선되는 장점을 지닌다. 또한, Valley-fill과 인덕터를 적용한 1단 구성으로 효율개선 및 역률 개선의 장점과 입력 전류 리플의 감소로 인한 EMI 노이즈 저감 효과를 나타낸다. 본 논문에서는 제안된 회로의 타당성을 검증하기 위하여 13W급 조명용 LED 구동회로의 시작품 제작을 통해 그 우수성을 확인한다.