Wide Operating Range Single-Stage Onboard Electric Vehicle Charger Using Impedance Control Network Architecture

This paper proposes an impedance control network (ICN)-based single-stage electric vehicle (EV) onboard charger with fully soft-switching capability for wide input and output voltage ranges. Auxiliary zero voltage switching (ZVS) inductor-based approach is presented in order to achieve soft-switching in the high frequency rectifier transistors while preserving the power factor correction (PFC) and inverter soft-switching properties of the conventional single-stage ICN-based ac-dc converter. The proposed ICN-based onboard charger is further optimized by realizing ZVS inductor using the magnetizing inductance of the isolation transformer, thereby eliminating the need for a discrete inductor. Furthermore, a design methodology is demonstrated to determine the optimal ZVS inductance needed to ensure full soft-switching capability for wide operating conditions. To validate the proposed design, a 1.7-kW, universal-input (90 Vrms - 305 Vrms), wide output voltage (200 V - 500 V), EV onboard charger is designed, built and tested. The prototype maintains soft-switching on all high-frequency devices and achieves a peak efficiency of 93.5%.