• 전기전자학회논문지
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• 제27권4호
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• pp.587-600
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• 2023

본 논문에서는 315W급 65인치 UHD-TV용 LLC DC to DC 공진 컨버터에 사용되고 있는 Slim형 고주파 변압기의 최적화 설계에 대해서 나타낸다. 또한 본 논문에서는 LLC 공진 변압기의 코어 손실 분석, AC 권선 손실 분석 및 권선 배치 최적화 설계를 통해 Slim형 고주파 변압기의 최적화 설계를 수행한다. 특히 본 논문에서는 이론적으로 해석하여 얻어진 결과를 토대로 고효율 및 Slim형 고주파 변압기는 교류 권선 손실 최소화 및 권선 자동화를 위하여 인터리브 및 수직형 권선 구조로 구성한다. 본 논문 제안한 수직형 권선 구조 방식의 Slim형 고주파 변압기의 1차측 권선은 Litz 권선을 2차 권선은 PCB와 동판 권선을 사용하였다. 최종적으로 Maxwell 2D 및 3D Tool을 이용한 시뮬레이션 결과를 토대로 이론 해석의 정당성을 입증하기 위해서 실험 결과를 통해 본 논문에서 제안한 Slim형 고주파 변압기의 최적화 설계를 수행하였다.

• 전기학회논문지
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• 제61권8호
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• pp.1130-1139
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• 2012

This paper proposes a LED lighting system using integrated power system composed of bridgeless PFC, LLC DC-DC transformer, and dimmable constant current LED driver module. The proposed LED lighting system features high efficiency, high power factor, and dimming capability. In order to verify the validity of the proposed system, the 2kW prototype system was built and tested. From the experimental results, it was confirmed that the maximun efficiency of 92.6% and maximum power factor of 99.7% can be achieved.

• 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.

• 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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• 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.

• 전력전자학회논문지
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• 제20권3호
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• pp.262-272
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• 2015

An integrated two-in-one transformer applicable to PSUs for a 120 W LED TV is proposed. This transformer comprises a PFC inductor and an LLC transformer placed and integrated on an E-I-E type magnetic core. Performance is evaluated by observing the coupling coefficients of the proposed two-in-one transformer under various air gap topologies. Among the topologies studied, an integrated transformer with centered air gap shows stable operational characteristics with a minimized mutual coupling (interference). Furthermore, applicability of the proposed integrated transformer to PSUs for a 120 W LED TV is studied from the viewpoint of integrating different magnetic components into one core, resulting to low weight, low cost, and high power density.

• 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.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2006년도 전력전자학술대회 논문집
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• pp.46-49
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• 2006

The LLC series resonant converter with a LLT(Inductor-Inductor-Transformer) transformer for PDP V sustaining 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 simulation based on the theoretical analysis and the 400W experimental prototype.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.333-344
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• 2018

This proposed paper aims for the high efficiency contactless power transfer in household dc power distribution. A 300 W five-level diode clamped multi-level converter with 300 Vdc input dc link bus is employed for the power transferring task and the output voltage range is controlled at 48 Vdc. The inner and outer solenoid coils are used for inductive power transfer (IPT) transformer with the 200 kHz switching frequency for designed power density. Therefore, to achieve the converter efficiency above 95%, the LLC series resonant with fundamental harmonic analysis (FHA) and the calculated switching angles are used as an optimized tool for designing the system resonant tank. The validations of this approached topology are illustrated in both MATLAB/Simulink simulation and implementation.

• 전력전자학회논문지
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• 제27권3호
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• pp.237-246
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• 2022

This paper proposes a method to adjust the turn ratio of a transformer for the high-efficiency operation of an LLC converter with a wide input range in a wired/wireless integrated charging system for electric vehicles. The characteristics of the inductive power transfer converter in the integrated charging system are analyzed to design the LLC converter, and the DC-link voltage range is derived. The aspect of voltage gain following each parameter of the LLC converter is analyzed, and the resonant network and transformer are designed. Based on the designed parameters, the feasibility of the design and control method is verified by implementing the operation of the LLC converter according to the DC-link and battery voltages.