Design of CRM AC/DC converter for very high-frequency high-density WBG-based 6.6kW bidirectional on-board battery charger

The wide-band-gap (WBG) devices based 6.6 kW bidirectional on-board charger (OBC) system for plug-in electric vehicles (PEVs) is recently developed. With the proposed novel variable DC-link voltage system architecture, high frequency soft switching operation, and integrated magnetics, the OBC system becomes more compact and more efficient compared to a Si-based counterpart. The design considerations of the AC/DC stage are introduced in this paper including the evaluation of 1.2 kV SiC MOSFETs; the zero-voltage-switching (ZVS) extension function for the line-cycle ZVS operation; and the novel universal control strategy for both the rectifier mode and the inverter mode. The prototype of the AC/DC stage is built which achieves 98.5% efficiency at higher than 300 kHz switching frequency. Finally, the complete 6.6 kW OBC system using both SiC and GaN devices is demonstrated with 37 W/in
³
power density and above 96% efficiency.