Wide output voltage range EV charger based on LLC resonant topology
MA Ling fu, WANG Teng fei, DAI Kai qi, WANG Zheng shi
(College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China)

Abstract: Aiming at the design problem of DC DC converter in electric vehicle, the wide range of application requirement of vehicle DC DC converters was analyzed,and the problems of wide range DC DC converter using LLC topology were summarized. The error caused by the traditional fundamental wave analysis method in a wide range of DC DC converters was very large, it was verified by no load LLC gain analysis. A new design method combined with the limitation of fundamental wave analysis and simulation was proposed, which greatly reduced the error of gain analysis and was very effective for efficiency optimization. Finally, a 2kW experimental prototype was built to validate the theoretical analysis. Based on the design method proposed in this paper, the design steps of the key parameters of the circuit were given. The results indicate that the prototype can achieve soft  switching under 10%-100% load, and the maximum efficiency is 97.1%.

Key words: wide range LLC; DC DC converter; vehicle power supply;