Three phase power factor corrected isolated buck for 48 V/100 A rectifier with secondary active clamp

A novel active clamp circuit for the secondary diodes of an isolated three phase buck converter is presented. The voltage spike on the diodes is clamped to permit the use of lower voltage rating diodes and the energy trapped in the transformer leakage inductance due to the reverse recovery current of the diodes is recycled to the output. The principle of operation of the active clamp with the three phase buck is analyzed and verified on a 6 kW prototype.