LLC resonant converter; Battery charger; High efficiency; Adaptive turn ratio; Wide output voltage
Issue Date
2018-01
Publisher
KOREAN INST ELECTR ENG
Citation
JOURNAL OF ELECTRICAL ENGINEERING & TECHNOLOGY, v. 13, no. 1, page. 124-132
Abstract
This paper proposes an LLC resonant converter based battery charger which utilizes an adaptive turn ratio scheme to achieve a wide output voltage range and high efficiency. The high frequency transformer of the LLC converter of the proposed strategy has an adaptively changed turn ratio through the auxiliary control circuit. As a result, an optimized converter design with high magnetizing inductance is possible, while minimizing conduction and turn-off losses and providing a regulated voltage gain to properly charge the lithium ion battery. For a step-by-step explanation, operational principle and optimal design considerations of the proposed converter are illustrated in detail. Finally, the effectiveness of the proposed strategy is verified through various experimental results and efficiency analysis based on prototype 300W Li-ion battery charger and battery pack.