Dual Transformer-Based Single-Stage Converter for EV Fast Charger with Flat Efficiency Characteristics

This article presented a reconfigurable bidirectional single-stage converter for fast charging applications. The proposed converter is designed for high-power, and a wide voltage range operation to accommodate both 400V and 800V battery-class electric vehicles. This converter achieved flat efficiency using pre-set AC relays for both EV battery classes. In addition, this article presented optimal control variables to increase conversion efficiency and power quality. As a result, soft switching is achieved from 150 to 920V battery voltage. Experimental results from the single module of the 8.4 kW EV charger prototype are provided to verify the theoretical claims. The peak efficiency of 96.7% is achieved. Furthermore, this converter exhibits flat efficiency performance for all charging battery voltage ranges.