A Battery Charging Method with Natural Synchronous Rectification Features for Full-bridge CLLC Converters
Huan Chen, Kai Sun, Haixu Shi, Jung-Ik Ha, Sangwon Lee
Abstract
CLLC converter is a promising topology for bidirectional power conversation applications, such as vehicle-to-grid (V2G) systems and battery energy storage (BES) systems. Battery charging is one of the most important functions of the CLLC converter in V2G and BES applications. Synchronous rectification (SR) is of vital importance in these applications because it can increase efficiency. a battery charging method with natural synchronous rectification features is proposed for the full-bridge CLLC converter. The proposed method consists of a parameter matching design procedure and synchronous rectification control. Different from the existing SR methods, the parameter design process is taken into the consideration of the SR realization. After the parameter matching design procedure, the required on-state time of the secondary side switches for the SR is nearly fixed during the whole charging process. As a result, the SR drive signal can be generated directly according to the switching frequency. No sensor detection or software estimation is needed, allowing natural synchronous rectification to be realized simply. Experimental results show an obvious efficiency improvement over the uncontrolled rectification, and the synchronous rectification of the proposed method is nearly the same as complete synchronous rectification during the whole battery charging process.