Novel resonant snubber based soft-switching inverter

A new soft-switching inverter has been developed to overcome over-voltage and over-current problems in the existing resonant link inverters. This inverter uses a single auxiliary switch and a resonant inductor per phase to produce a zero voltage across the main switch so that the main switch can turn on at a lossless condition. Both the auxiliary switch and the resonant inductor are operating at a fractional duty, and thus are small in size compared to the main inverter circuit components. Although the resonance can be obtained with the use of the stray capacitance across the main switch, typical implementations require a small capacitor paralleling with the main switch to obtain nearly lossless turnoff. This paper describes both three-phase and single-phase circuit configurations.