Multiblock Soft-Switched Bidirectional AC–AC Converter Using a Single Loss-Less Active Snubber Block

A multiblock soft-switched bidirectional ac-ac converter using an active snubber is proposed in this paper. The snubber provides zero-voltage switching (ZVS) for the main switches of the entire power converter blocks in the entire input voltages and polarities. To achieve ZVS operation, the snubber block extracts the energy of the main switch drain-source capacitors and delivers it to the high-voltage side. Moreover, the snubber switches have zero-current switching (ZCS) turn-on and ZVS turn-off transitions. The performance of the proposed converter system is evaluated on a prototype including two converter blocks of 500 W working at 150 kHz with an input-voltage range of 110 V (-30% to +20%) and output of 175 V. Experimental results confirm that the proposed snubber improves the efficiency by 3% (4%) at half (full) load power for the entire input-voltage range.