• 전력전자학회논문지
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• 제23권3호
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• pp.208-216
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• 2018

In this paper, an LLC resonant converter employing two coupled inductors on the secondary side of the converter is proposed. The conventional LLC converter exhibits serious power loss during secondary winding of the transformer because of generation of tremendous output current ripples. To overcome this problem, an LLC resonant converter with a current doubler as a rectifying circuit was recently proposed. However, the current-doubler rectifying circuit requires coupled inductors with a high coupling ratio to retain the designed resonance characteristics. Therefore, an additional hardware filter is required at the output stage to address large output current ripples. Additional design procedures are also necessary because the inductance component of the added filter affects the designed resonant network. To solve this issue, an LLC resonant converter employing two coupled inductors is proposed in this paper. Mathematical analysis shows that the proposed secondary-side current-doubler circuit does not affect the designed resonance characteristics. The operating principles and theoretical analyses are proven through a simulation and experiments with a 54 V/28 A prototype.

• 전력전자학회논문지
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• 제14권4호
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• pp.323-332
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• 2009

본 논문에서는 다 출력 LLC 공진 컨버터의 동작 특성 대해 서술하였고 분석하였다. 특히 다 출력 변압기의 2차 측 인덕턴스와 여러 부하조건에 따른 영향에 의해 다 출력 LLC 공진 컨버터의 전압이득특성 및 등가공진주파수가 변한다. 따라서 출력이 다 출력일 때 부하에 따른 공진 특성 변화와 이득 변화를 확인하였고, 또한 부하 동 특성을 고려한 설계와 전압이득 특성을 기본으로 하여 42인치 PDP TV용 전원에 540W 3-output LLC 공진컨버터를 적용하여 실험한 결과를 보였다.

• 전력전자학회논문지
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• 제17권4호
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• pp.281-290
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• 2012

This paper describes a Cross-regulation characteristics of a multi-output LLC resonant converter widely used in consumer electronics. The output characteristics of the multi-output LLC converter is derived from the assumption that the current and voltage in the resonant network is sinusoidal and the duty loss exists. The simulation and experimental results are provided to verify the theoretic results.

• 조명전기설비학회논문지
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• 제27권4호
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• pp.48-53
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• 2013

In general, the LLC resonant topology consists of three stages as; square wave generator, resonant network, and rectifier network. LLC resonant converter has the time slowly varying parameters. However, the power LEDs as the load of LLC converter can be regarded as fast time varying parameters. In this paper, the mathematical model of half-bridge resonant converter including with the power LEDs is introduced for the current controller design model. Using this controller design model, the parameter adaptive output feedback controller will be designed to control the power LEDs current. In order to show the validities of the proposed model, the parameter adaptive output feedback controller, the experimental investigation will be presented.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권8호
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• pp.423-429
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• 2006

Recently, the high frequency isolated boost DC/DC converter has been widely used for the PCS (Power Conditioning System) system because of its small size and low cost. However, the high frequency isolated boost DC/DC converters applied the conventional voltage-fed converter and current-fed converter have the problems such as the high conduction losses and the surge voltage due to the high circulating current and the leakage inductance, respectively. To overcome this problems, in this paper the secondary LLC resonant converter is proposed, and the experimental results of the secondary LLC series resonant converter for boost DC/DC converter are verified on the simulation based on the theoretical analysis and the 700W experimental prototype.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.347-350
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• 2006

The high efficiency full-bridge LLC resonant converter using a contact-less transformer is proposed for the photovoltaic power generation system. For the series resonance with a series capacitor, the LLC resonant converter utilizes the leakage inductance and magnetizing inductance of a contact-less transformer. Unlike the conventional series resonant converter operated to the continuous resonant current at above resonance frequency, the proposed converter operates to the discontinuous resonant current at the narrow frequency control range below resonance frequency. Due to the discontinuous mode resonant current, the proposed converter can be achieved the zero voltage switching (ZVS) in the primary switches and the zero current switching (ZCS) in the secondary rectification diodes without any auxiliary circuit. In this paper, the experimental results of the proposed full-bridge LLC resonant converter using a contact-less transfonner are verified on the simulation based on the theoretical analysis and the 150W experimental prototype.

• 전력전자학회논문지
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• 제21권2호
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• pp.102-110
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• 2016

In this paper, a high-frequency dual mode control LLC resonant converter with wide input voltage range is proposed through zero voltage switching (ZVS) under the universal line input voltage and every load conditions. Conventional small power adapter driving should be satisfied with universal line input voltage because it has no power factor correction circuit regulation. The conventional LLC resonant converter for an adapter can reduce the size of transformer in terms of high-frequency driving and ZVS. However, this converter has a disadvantage in terms of design of resonant tank under various input voltages because the frequency modulation range is very wide to satisfy voltage conversion gain. Compared with the conventional one, the proposed LLC converter can be adapted to universal line input voltage and high-frequency driving because it is controlled by pulse width modulation and pulse frequency modulation with control voltage. The validity of the proposed LLC converter is proved through the 60 W prototype.

• 한국전자통신학회논문지
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• 제9권1호
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• pp.91-96
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• 2014

최근 양산되고 있는 하이브리드 전기자동차에 비해서 연비를 좀 더 개선하기 위한 플러그인 하이브리드 전기자동차(Plug-in Hybrid Electric Vehicle)에 대한 연구가 활발히 진행되고 있다. 이 논문에서는 플러그인 하이브리드 전기자동차를 위한 고효율의 탑재형 충전기(on-board charger)에 대해서 연구한다. 탑재형 충전기는 2상 인터리브드 PFC 회로와 LLC 공진형 컨버터로 구성된다. LLC 공진형 컨버터의 새로운 설계절차를 본 논문에서 제안한다. 이는 매우 쉽고 강력한 방법이다. 위에서 언급한 내용을 확인하기 위해서 LLC 공진형 컨버터를 설계하고 PSIM 툴을 이용하여 테스트한다.

• 전력전자학회논문지
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• 제12권6호
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• pp.472-482
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• 2007

본 논문에서는 PDP TV 전원에 적용된 LLT 변압기를 사용한 LLC 직렬공진 컨버터의 설계과정과 실험결과에 대해 서술하였다. 인덕터와 변압기를 하나의 변압기로 사용한 LLT 변압기는 전선방법과 코어의 공극에 따라 1, 2 차측 누설인덕턴스가 함께 증가한다. 이러한 LLT 변압기의 증가된 1, 2차측 누설인덕턴스는 LLC 직렬공진컨버터의 DC 전압이득에 영향을 준다. 따라서 본 논문에서는 LLT 변압기 적용 LLC 직렬 공진 컨버터의 전압이득 특성과 실험 결과에 대해 Math-CAD 시뮬레이션을 기본으로 한 이론적인 해석 및 600W 시제품을 통해 증명하였다.

• 전력전자학회논문지
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• 제25권2호
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• pp.142-151
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• 2020

This paper presents a DC/DC LLC resonant converter with wide input/output voltage gain characteristics and its control method for efficiency improvement. For a wide input/output voltage gain characteristics without designing small transformer magnetization inductance, the proposed converter changes the topology into three modes of operation according to the main switch switching pattern. In each operating mode, variable LINK voltage modulation and frequency modulation were performed to control output voltage and improve operating efficiency. A prototype of a 5-kW DC/DC LLC resonant converter was built and tested to verify the validity and applicability of the proposed converter.