A new leakage energy commutation technique for single stage high frequency link inverters

This paper presents a commutation technique to overcome the effects of transformer leakage inductance in a single stage high frequency ac-link transformer isolated inverter. The presence of leakage inductance causes large voltage spikes across the transformer due to the switched nature of link current that is encountered in direct high frequency ac link to low frequency ac conversion. This paper proposes a partial resonant technique where a capacitor is connected across the link only during the instants when the current in the link needs to change its polarity. This results in a resonant current transition which eliminates the problem of abrupt current transition through an inductor. The proposed technique results in the recovery of the leakage energy to a large extent and also results in soft switching during majority of the switching transitions resulting in enhanced efficiency. The proposed scheme is implemented in the SIMULINK software environment and results are presented.