An active auxiliary commutation circuit for inverters

This paper proposes an active auxiliary commutation circuit (AACC) to achieve zero voltage switching (ZVS) in DC-AC power converters. The switching strategy implemented and the AACC make it possible for these power converters to operate with soft commutation of their main switches from no load up to full load, without increasing their voltage or current ratings. Due to commutation under zero voltage conditions, the main switches are implemented as a dual thyristor. The RMS current value carried by auxiliary switches is very low. To verify the feasibility of the proposed AACC, it is applied to a half-bridge inverter. Operation principle, commutation analysis, switching strategy and features are described and verified experimentally. These results have been obtained from a laboratory prototype operating at 30 kHz and rated at 300 W.