Three-phase isolated soft-switching DC-DC converter with secondary phase shift modulation

A novel three-phase isolated soft-switching DC-DC converter suitable for medium voltage high current applications is proposed. The converter consists of a three-phase full bridge, a high frequency transformer and a three-phase active rectifier. With secondary phase shift modulation, zero voltage switching for all primary switches and zero current switching for all secondary switches are achieved from no load to full load. Switch and transformer parasitics are utilized to assist in soft switching. Since the energy required to charge/discharge switch output capacitance comes from output inductor rather than leakage inductance, the design for transformer is greatly simplified. Simulation and experimental results verify the operation of proposed converter.