• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.23-24
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• 2011

In this paper, the 170W LLC half bridge DC-DC converter is designed for the lighting management system. The power conversion circuit consists of PFC and isolated LLC resonant converter. The topology of LLC half bridge resonant converter provides ZVS characteristic. And the stresses of voltage and current is smaller than that of the general resonant converters. So we can expect the higher efficiency. The optimal conditions for high efficiency were investigated through by experiment.

• 전력전자학회논문지
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• 제17권2호
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• pp.121-128
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• 2012

In this paper, a new planar transformer with a novel core configuration that can regulate the leakage inductance is proposed and described in detail. In order to design the slim size power system for flat panel TV, Two planar transformers applied to LLC resonant converter are connected in series at primary and in parallel by the center-tap winding at secondary. In this paper, a 300W low profile LLC resonant converter was built and tested to verify the proposed planar transformer.

• 전력전자학회논문지
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• 제16권6호
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• pp.627-637
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• 2011

본 논문은 새로운 형상을 가지는 평면 변압기를 적용한 200W급 공진컨버터에 대한 내용이다. 제안된 평면변압기는 기존 누설인덕턴스가 작은 평면변압기와 달리 누설인덕턴스가 조정이 가능하여 원하는 공진 특성을 얻을 수 있는 특징을 가지는 저가형 고집적화에 용이한 변압기이다. 본 논문에서는 제안된 평면변압기를 적용하여 200W급 전원장치에 적용하여 실험하였으며, 실험결과와 이론적인 해석에 대해 서술하였다.

• 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.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.285-286
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• 2015

In this letter, a simple control method of the HB LLC converter with one additional switch and capacitor in the primary side is proposed for wide-input-voltage applications with the hold-up time conditions. At nominal input, since the proposed method enables the HB LLC converter to operate with large transformer magnetizing inductance, it can reduce the conduction and switch turn-off losses in the primary side, which makes a high efficiency. On the other hand, during the hold-up time, since the proposed method increases the resonant capacitance by turning on one additional switch, the HB LLC converter can obtain high voltage gain.

• 전력전자학회논문지
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• 제26권1호
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• pp.46-52
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• 2021

This study proposes a feedforward compensation control method to reduce 120 Hz output voltage ripple in a single-phase AC/DC rectifier system composed of PFC and LLC resonant converters. The proposed method compensates for the voltage ripple of the DC-link by using the AC input and DC output power difference, and then reduces the final output voltage ripple component of 120 Hz through feedforward compensation based on the linearized frequency gain curve of the LLC resonant converter. Through simulation and experimental results, the validity of the ripple reduction performance was verified by comparing the conventional PI controller and the proposed feedforward compensation method.

• 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 2005년도 전력전자학술대회 논문집
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• pp.289-291
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• 2005

In this paper results of the experiment which used LLC resonant half bridge DC-DC converter to a portable electrical equipment. LLC resonance Half Bridge DC-DC converter which was used in this experiment improved an efficiency because it reduced switching, conduction losses and with synchronous rectifier. As a result of the experiment, this proposed converter could verified an increase of 2% to the efficiency more than diode rectifier.

• 전력전자학회논문지
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• 제11권5호
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• pp.409-416
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• 2006

LLT 변압기 적용 LLC 직렬공진컨버터의 동작특성에 대해 설명하였다. 본 논문에서는 1차측 권선과 2차측 권선을 분리하고, 변압기 중간에 공극(Air-Gap)을 삽입한 일체화된 LLT 변압기를 적용하였다. 이와 같이 적용된 LLT 변압기의 경우 1차측 누설인덕턴스만이 증가되는 것이 아니고 2차측 누설인덕턴스 또한 증가되게 된다. 이렇게 증가된 2차측 누설인덕턴스는 전압이득 특성곡선에 있어 LLC 직렬공진컨버터에 적용한 변압기를 사용한 경우보다 전체적으로 높은 전압이득 특성을 가지게 된다. 따라서 본 논문에서는 2차측 누설인덕턴스를 고려한 일체화된 LLT 변압기적용 LLC 직렬공진컨버터에 대해 이론적으로 해석하고 시뮬레이션 하였으며, 400W급 시제품을 제작하여 실험한 결과에 대해 서술하였다.

• Journal of Electrical Engineering and Technology
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• 제8권6호
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• pp.1400-1408
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• 2013

This paper proposes a new grid-tied power converter for battery energy storage, which is composed of a 2-stage DC-DC converter and a PWM inverter. The 2-stage DC-DC converter is composed of an LLC resonant converter connected in cascade with a 2-quadrant hybrid-switching chopper. The LLC resonant converter operates in constant duty ratio, while the 2-quadrant hybrid-switching chopper operates in variable duty ratio for voltage regulation. The operation of proposed system was verified through computer simulations. Based on computer simulations, a hardware prototype was built and tested to confirm the technical feasibility of proposed system. The proposed system could have relatively higher efficiency and smaller size than the existing system.