Mobile QR Code QR CODE : The Korean Institute of Power Electronics
Title A Study on LLC Resonant Converter Employing Coupled Inductor to Reduce Output Current Ripple
Authors Yong-Chul Lee ; Min-Hyuck Kang ; Chan-Ho Kang ; Sung-Soo Hong
Page pp.208-216
ISSN 1229-2214
Keywords LLC Resonant converter ; Low output current ripple ; Current doubler circuit ; Coupled inductor ; High coupling ratio
Abstract 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.