An Improved Control Scheme for Reducing Circulating Current and Reverse Power of Bidirectional Phase-Shifted Full-Bridge Converter

The phase-shifted full-bridge (PSFB) converter is widely adopted in electric vehicles and energy storage applications. However, it suffers from several technical drawbacks such as voltage overshoot, hard switching, severe circulating current, and large reverse power. To address such issues, an improved control scheme is proposed to enhance the performances of bidirectional operation in the PSFB converter. In this method, the precharge stage and the cocharge stage are added by adjusting the phase-shift angle and duty ratio. The reverse power, circulating current, and transformer root mean square current can be reduced with the cocharge stage. And, due to the precharge stage, this method can constrict voltage overshoot very well, while achieving zero current switching on the large current side devices and zero voltage switching on the high-voltage side devices nearly along all the load range. The proposed method is described, analyzed, and validated in a 1-kW prototype, which presents 96.1% peak efficiency and improves average efficiency by about 2% in the experimental results.