Single-stage Bi-directional Matrix Converter with Regenerative Flyback Clamp Circuit for EV Battery Charging

The power converter configuration plays a significant role in charging of the electric vehicle (EV) batteries. The efficiency, bi-directional power transfer capability, power factor correction (PFC), etc. all depend on the selection of the suitable converter topology. This paper proposes an isolated single-stage bi-directional matrix-type AC-DC converter with flyback based clamp circuit for EV battery charging application. The proposed converter is developed with a half-bridge (HB) cycloconverter in the AC side, and a full-bridge (FB) inverter at the DC side. A soft switched unipolar pulse width modulation (UPWM) scheme is presented for both grid to vehicle (G2V) and vehicle to grid (V2G) mode of operation. The proposed converter requires a clamp circuit to provide seamless commutation for the current flowing through the filter inductor and leakage inductor of the high-frequency transformer. A flyback based regenerative clamp circuit is proposed for this purpose, which ensures significant reduction in power loss due to its regeneration capability. The converter performance with the proposed modulation scheme is evaluated in a SiC MOSFET based 1.5 kW prototype unit.