LLC resonant converter for electric vehicle battery chargers

Abstract

This study presents a new LLC resonant converter with two transformers in parallel for the electric vehicle battery charger. This topology achieves the zero‐voltage switching for main switches in the entire charging profile. In addition, the zero‐current switching for output rectifier diodes is extended under charging condition. The proposed charger provides a wide range output voltage for the battery system. Moreover, in order to maintain the high efficiency under charging, the charger adopts a bidirectional switch. At low‐output power condition, the charger uses one transformer to transfer the energy. Finally, the design procedure is provided and implemented in a prototype charger with the input DC link 400 V and the output voltage of 36–58 V. Experimental results are presented to demonstrate the system performance. The maximum power is up to 700 W and the peak efficiency is as high as 93.6%.