Multifunction Capability of SiC Bidirectional Portable Chargers for Electric Vehicles

Abstract

A SiC bidirectional portable charger is proposed to realize both bidirectional ac–dc and bidirectional dc–dc high-efficiency power conversion by multiplexing the same powertrain. Control strategies for different operation modes are proposed to realize the comprehensive functions of the portable charger. The proposed portable charger enables the EV to interact with the ac grid, dc microgrid, other EVs, and off-line loads efficiently and conveniently. The SiC portable charger adopts 300-kHz high-frequency isolation to improve the power density. The proposed vehicle-to-vehicle (V2V) mode adopts two-stage direct dc–dc power conversion so that it achieves higher efficiency compared with conventional V2V mode using an on-board charger (OBC). A 6.6-kW SiC bidirectional portable charger is built and the power density is 14.7 W/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The full-load efficiency of V2V mode is 96.1%, which is 4.7% improved compared with the conventional V2V mode. Bidirectional energy interaction between EV and the 380-V dc microgrid is also verified. The portable charger provides 36–400-V wide output voltage for dc loads with the efficiency above 95.7% at 6.6 kW.