Regenerative Undeland Snubber Using a ZVS PWM DC–DC Auxiliary Converter Applied to Three-Phase Voltage-Fed Inverters

This paper proposes an energy regeneration circuit for three-phase voltage-fed inverters using a modified Undeland snubber. The proposed system uses a quasi-square-wave zero voltage switching dc-dc auxiliary converter to regenerate the energy from snubber capacitor to the dc bus. The regenerative circuit uses a single active switch, and it operates independently of the three-phase inverter. Operation stages, theoretical waveforms, and a design methodology are presented. Experimental results based on a 4.5-kVA three-phase inverter prototype are included to validate the proposed topology.