• 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.

• 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.

• Journal of Power Electronics
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• 제7권1호
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• pp.13-20
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• 2007

LLC resonant converters display many advantages over the conventional LC series resonant converter such as narrow frequency variation over wide range of load and input variation and zero voltage switching even under no load conditions. This paper presents analysis and design consideration for the half bridge LLC resonant converter. Using the fundamental approximation, the gain equation is obtained, where the leakage inductance in the transformer secondary side is also considered. Based on the gain equation, the practical design procedure is investigated to optimize the resonant network for a given input/output specifications. The design procedure is verified through an experimental prototype of the 115W half-bridge LLC resonant converter.

• Journal of Power Electronics
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• 제8권3호
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• pp.275-279
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• 2008

An LLC series resonant converter has many unique characteristics and improvements over PWM topologies. However, many output capacitors are needed in parallel to satisfy output voltage ripple and the rated ripple current of the capacitors. This paper deals with a novel two phase interleaved LLC resonant converter using a phase of the resonant capacitor. The proposed converter can satisfy output voltage ripple and a rated ripple current of capacitors with few output capacitors, relatively. The operation and features are considered in detail and a prototype with a 12V-100A output is investigated.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.526-528
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• 2008

LLC series resonant converter has many unique characteristics and improvement over PWM topologies. However, many output capacitors should be needed in parallel to satisfy an output voltage ripple and a rated ripple current of the capacitors. This paper is deal with a novel two phase interleaved LLC resonant converter using a phase of the resonant capacitor. The proposed converter can satisfy output voltage ripple and a rated ripple current of capacitors with few output capacitors, relatively. The operation and features is considered in detail and a prototype with a 12V-100A output is investigated.

• 전기학회논문지
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• 제67권3호
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• pp.398-405
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• 2018

LLC resonant converter is popular with industrial fields because it can be achieved high efficiency by zero voltage switching (ZVS). As interest grew, analysis of characteristics in LLC resonant converter have been actively studied. Generally, characteristic of LLC resonant converter is analyzed based on first harmonic approximation(FHA). The FHA analysis represents the characteristics of LLC resonant converter by obtaining the series resonant operation. FHA analysis of LLC resonant converter in load condition is correct. but it is not correct in no load condition. This paper proposed analysis of characteristics considering the parasitic components to overcome the limitation of FHA and analyze no-load characteristics. The validity of the proposed method has been investigated by simulation and experimental results.

• 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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• 제19권5호
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• pp.440-449
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• 2014

This study proposes an LLC series resonant converter with a current doubler using a coupled inductor as a rectification circuit for the secondary side. The current doubler circuit is generally used for a high-voltage input and low-voltage output circuit to obtain high efficiency with small transformer turn ratio. However, an inductive circuit is not generally used in the secondary side of an LLC series resonant converter. If inductive components exist on the secondary side, the resonant characteristics are changed through the secondary inductive circuit. Mathematical analysis shows that the secondary-side current doubler with coupled inductor is not affected by the resonant characteristic of the primary LLC if leakage inductance occurs in the coupled inductor. Results of the analysis are proven by simulation; an experiment is also conducted for the proposed circuit.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.424-427
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• 2007

The LLC series resonant converter with a LLT (Inductor-Inductor-Transformer) transformer for PDP power supply is presented. LLT transformer used to combine the inductor and transformer into one unit has the increased leakage inductance in the primary and secondary due to the winding method and the use of the gaped core. The increased leakage inductance in the primary and secondary of LLT transformer can be impacted on the DC voltage gain characteristics of LLC series resonant converter. In this paper, DC gain characteristics and the experimental results of the LLC series resonant converter with a LLT transformer are verified on the Math-CAD simulation based on the theoretical analysis and the 600W experimental prototype.

• 전력전자학회논문지
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• 제14권3호
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• pp.177-187
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• 2009

본 논문에서는 다중 출력을 갖는 LLC 직렬 공진 컨버터의 입출력 이득에 대한 새로운 해석법을 제시한다. 특히 Math-CAD 시뮬레이션을 통해 변압기 2차 측 누설인덕턴스 성분에 의한 주파수 이득특성 변화를 분석한다. 유도된 수식 이론을 근거로, 3개의 출력을 갖는 430W급 공진 컨버터를 제작하여 46인치용 PDP 파워모듈의 Sustain 블록에 적용함으로서, 제안된 해석법의 정확성을 검증한다.