Efficiency improvement on LLC resonant converter using integrated LCLC resonant transformer

Abstract

This paper presents the efficiency improvement on the comparative half-bridge LLC resonant converter using the integrated LCLC resonant transformer. Large leakage inductance is demanded for the conventional isolated LLC resonant converter to have high power factor of the resonant tank. However, large leakage inductance causes lower efficiency and the electromagnetic interference noise. In order to reduce the demanded leakage inductance of the LLC resonant transformer, a parallel resonant capacitor can be paralleled to the magnetizing inductor through the connection of an auxiliary winding as an LCLC resonant transformer. Finally, the resonant transformer of a 300W comparative LLC resonant converter is converted as an integrated LCLC resonant transformer for lower leakage inductance to improve the power conversion efficiency. Then, the DC-DC half-bridge converter with the integrated LCLC resonant converter is implemented and experimented to verify the power conversion efficiency rather than the comparative half-bridge converter with the LLC resonant transformer.