• 전기학회논문지
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• 제65권4호
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• pp.601-610
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• 2016

The light-emitting diode (LED) has been used in a variety of industrial fields and for general 0lighting purposes on account of its high efficiency, low power consumption and long lifespan. The LED is driven by direct current; therefore, an AC/DC converter is typically required for its use. An electrolytic capacitor is generally used for stabilizing DC voltage during use of the AC/DC converter. However, this capacitor has a short lifespan, which makes it a limiting factor in LED lighting. Furthermore, LED lighting requires a dimmable control to enable energy savings and fulfil a growing consumer demand. In this paper, the dimmable single-stage power factor correction (PFC) continuous conduction mode (CCM) flyback converter that employs no electrolytic capacitor is presented. The LC resonant filter is alternatively applied to reduce the 120[Hz] ripple on the output. And the optimum value of the LC resonant filter parameters considering both efficient and performance is analysed. Simulation and experimental results verify the satisfactory operation of the converter.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2006년도 전력전자학술대회 논문집
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• pp.363-365
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• 2006

소비자의 요구와 기술력의 발달로 PDP시장은 42인치와 60인치등 대형PDP가 주류를 이루고 있으며 대형화에 따라서 PDP전원의 소모전력 또한 $400W{\sim}600W$ 까지 증가 하고 있다. 기존 소용량 PDP전원으로 사용되던 Flyback의 경우 소모 전력이 증가함에 따라 대형PDP에 적용하기에는 소자 내압 및 시스템 효율 측면에서 다소 무리가 있다. 따라서 대형PDP의 전원을 위해서 새로운 2 Switch 3 Diode를 채용한 고효율 DCR (Diode Clamping Rectifier) Flyback Converter를 제안하였으며 이를 42인치 PDP에 적용하여 회로의 타당성 및 우수성을 검증하였다.

• Journal of Power Electronics
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• 제11권4호
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• pp.499-506
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• 2011

This paper presents an interleaved active-clamping zero-voltage-switching (ZVS) forward-flyback converter without an output choke. The presented topology has two active-clamping circuits with two separated transformers. Because of the interleaved operation of the converter, the output current ripple will be reduced. The proposed converter can approximately share the total load current between the two secondaries. Therefore, the transformer copper loss and the rectifier diodes conduction loss can be decreased. The output capacitor is made of two series capacitors which reduces the peak reverse voltage of the rectifier diodes. The circuit has no output inductor and few semiconductor elements, such that the adopted circuit has a simpler structure, a lower cost and is suitable for high power density applications. A detailed analysis and the design of this new converter are described. A prototype converter has been implemented and experimental results have been recorded with an ac input voltage of 85-135Vrms, an output voltage of 12V and an output current of 16A.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권2호
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• pp.190-196
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• 2013

It presents a unification of buck-boost and flyback converter for driving a cascaded H-bridge multilevel inverter with a single independent DC voltage source. Cascaded H-bridge multilevel inverter is useful to make many output voltage levels for sinusoidal waveform by combining two or more H-bridge modules. However, each H-bridge module needs an independent DC voltage source to generate multi levels in an output voltage. This topological characteristic brings a demerit of increasing the number of independent DC voltage sources when it needs to increase the number of output voltage levels. To solve this problem, we propose a converter combining a buck-boost converter with a flyback converter. The proposed converter provides independent DC voltage sources at back-end two H-bridge modules. After analyzing theoretical operation of the circuit topology, the validity of the proposed approach is verified by computer-aided simulations using PSIM and experiments.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.138-139
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• 2017

This paper describes the design and implementation of a trigger circuit which can be series connected with main pulse circuit for a xenon flash lamp driver. For generating high voltage, the trigger circuit is designed as an inductive energy storage pulsed power modulator with 2 state step-up circuit consisting of a boost converter and a flyback circuit. In order to guarantee pulse width, a resonant capacitor on the output side of the flyback circuit is designed. This capacitor limits the output voltage to protect the flyback switch. In addition, to protect another power supply of xenon flash lamp driver from trigger pulse, the high voltage transformer which can carry the full current of main pulse is designed. To verify the proposed design, the trigger circuit is developed with the specification of maximum 23 kV, 0.6 J/pulse output and tested with a xenon flash lamp driver consisting of a main pulse circuit and a simmer circuit.

• 전력전자학회논문지
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• 제11권4호
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• pp.361-370
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• 2006

단일단 단일스위치 통기정류기형 플라이백 컨버터를 제안한다. 제안된 단일단 단일스위치에 의해 역률이 개선되었으며 IEC 61000-3-2의 고조파 전류 요구조건을 만족한다. Flyback 컨버터의 경우 2 차 측 정류용 다이오드로 사용되는 쇼트키 다이오드의 전압 강하에 의한 전력손실이 크며, 이러한 전력 손실을 줄이기 위해 정류용 다이오드를 대신하여 도통 저항이 작은 MOSFET을 사용함으로써 전력손실을 줄일 수 있으며 이를 동기정류기 (SR : Synchronous Rectifier)라 한다. 제안된 동기 정류기는 MOSFET의 드레인 소스간의 전압 강하를 이용하여 동작하는 VDSR(Voltage Driven Synchronous Rectifier)이며 효율 향상을 목적으로 한다. 본 논문에서 제안한 단일단 단일스위치 동기정류기형 플라이백 컨버터는 출력 전력 85W (l2V /7.1A)에 적용되었으며 실험결과를 통해 확인할 수 있다.

• 전력전자학회논문지
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• 제11권4호
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• pp.321-327
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• 2006

본 논문은 다출력 전원장치에 적용되는 플라이백 컨버터를 위한 자동 동기 스위치 포스트 레굴레이터를 제안한다. 제안된 회로는 기존의 스위치 포스트 레굴레이터의 단점인 구동회로 구현 및 주 출력과 보조 출력의 동기의 어려움으로 인한 복잡한 회로구성이 새로운 자동동기 스위치로 간단하게 구성된다. 제안된 회로를 적용함으로서 각 출력의 전압가변과 정밀한 레굴레이션이 요구되는 다중출력 전원장치를 간단한 구성과 저렴한 가격으로 제작할 수 있으며, 이론적 해석 및 시뮬레이션 그리고 실험을 통하여 제안 회로의 타당성을 입증하였다.

• Journal of Power Electronics
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• 제18권6호
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• pp.1642-1649
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• 2018

A single-stage flyback LED AC-DC converter based on primary-side control under constant current mode is proposed in this study. The proposed converter features low total harmonic distortion (THD) and high power factor (PF). It also consists of a zero-crossing distortion compensation circuit and a variable duty ratio control compensation circuit to deal with the line current distortions caused by fixed duty ratio control. The system model and layout are built in Simplis and Cadence, respectively. The feasibility and performance of the proposed circuit is verified by designing and fabricating an IC controller in the HHNEC $0.35{\mu}m$ 5 V/40 V HVCMOS process. Experimental results show that the PF can reach a level in the range of 0.985-0.9965. Moreover, the average THD of the entire system is approximately 10%, with the minimum being 6.305%, as the input line voltage changes from 85 VAC to 265 VAC.

• Journal of Power Electronics
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• 제19권4호
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• pp.1011-1019
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• 2019

In this paper, a buck-flyback (fly-buck) stand-alone photovoltaic (PV) system for charge balancing with a differential power processor (DPP) circuit is proposed. Conventional feed-back DPP converters draw differential feed-back power from the output of a string converter. Therefore, the power is always through the switches and diodes of the string converter. Because of the returning conduction path, there are always power losses due to the resistance of the switch and the forward voltage of the diode. Meanwhile, the proposed feed-back DPP converter draws power from the magnetically-coupled inductor in a string converter. This shortens the power path of the DPP converter, which reduces the power losses. In addition, the extra winding in the magnetically-coupled inductor works as a charge balancer for battery-stacked stand-alone PV systems. The proposed system, which uses a single magnetically-coupled inductor, can control each of the PV modules independently to track the maximum power point. Thus, it can overcome the power loss due to the power path. It can also achieve charge balancing for each of the battery modules. The proposed topology is analyzed and verified using 120W hardware experiments.

• 전력전자학회논문지
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• 제24권4호
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• pp.279-285
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• 2019

This study proposes an enhanced switching pattern that can improve energy transfer efficiency in an active cell-balancing circuit using a multiwinding transformer. This balancing circuit performs cell balancing by transferring energy stored in a specific cell with high energy to another cell containing low energy through a multiwinding transformer. The circuit operates in flyback and buck-boost modes in accordance with the energy transfer path. In the conventional flyback mode, the leakage inductance of the transformer and the stray inductance component of winding can transfer energy to an undesired path during the balancing operation. This case results in cell imbalance during the cell-balancing process, which reduces the energy transfer efficiency. An enhanced switching pattern that can effectively perform cell balancing by minimizing the amount of energy transferred to the nontarget cells due to the leakage inductance components in the flyback mode is proposed. Energy transfer efficiency and balancing speed can be significantly improved using the proposed switching pattern compared with that using the conventional switching pattern. The performance improvements are verified by experiments using a 1 W prototype cell-balancing circuit.