A two-stage bidirectional DC/DC converter with SiC-MOSFET for vehicle-to-grid (V2G) application

This paper proposes a two-stage bidirectional DC/DC converter for vehicle-to-grid (V2G). The two-stage converter is composed of the isolated CLLC bidirectional resonant converter and the non-isolated bidirectional converter. The CLLC converter has the symmetric resonant tank and is operated in the high-frequency which can reduce the volume of the transformer. The purpose of this converter is high-frequency isolation without control. The converter is operated in the resonant frequency and the gain is maintained to unity. The non-isolated converter performs the charging and discharging control. This converter has half-bridge structure which has problem in regard of the serious voltage stress of the switches by the hard-switching. To reduce the power loss and achieve the high efficiency, SiC-MOSFET is used in both converters. The proposed two-stage bidirectional converter is verified from PSIM simulation with 15-kW bidirectional DC/DC converter.