Soft switched full bridge dc-dc converter with reduced circulating loss and filter requirement

A new soft switched full bridge converter with phase-shift control is proposed to reduce the circulating loss in primary and the voltage stress in secondary side. Using a coupled winding of the filter inductor, two auxiliary voltage sources are generated to reset the primary current at circulating interval. An auxiliary clamp diode is used to clamp the voltage spike across the rectitier diode, which releases the voltage stress of the rectifier diode. Therefore, low break down voltage diodes are utilized to reduce the conducting loss and the reverse recovery loss. Also, the filter requirements are lowered due to the auxiliary voltage sources. A prototype is built up to verify the theoretical analysis. Index Terms--Phase shift full bridge (PSFB), zero voltage switching (ZVS).