Design of Bidirectional DC-DC Converter for Energy Storage System in High Power Application

In this study, the design of bidirectional DC-DC converter for high voltage energy storage systems (ESSs) to high voltage level DC-bus or power supply in power applications is proposed. The proposed converter consists of two stages: an interleaved buck/boost converter in the battery side and the three-phase wye-wye series resonant converter in the DC-bus. In the battery side, the interleaved buck converter allows the lower current stress in every switch, results in lower conduction loss. The three phase wye-wye converter with zero-voltage-switching (ZVS) condition in wide power range in the DC-bus side achieve very high efficiency, even at light load condition. The wye-wye connection of the transformer is employed to reduce to voltage stress of the primary and secondary side of the transformer. A 20kW prototype is built and tested to verify the feasibility of the proposed design.