Resonant snubber based soft-switching inverters for electric propulsion drives

This paper proposes the resonant snubber based soft-switching inverters for electric propulsion drives. The newly developed soft-switching inverter employs an 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 the zero-voltage 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. Operation modes in a complete zero-voltage switching cycle for the single-phase soft-switching inverter are described in detail with graphical explanations. The circuit operation was first verified by a computer simulation and then tested with a 1 kW single-phase and a 100 kW three-phase inverters. Experimental results are presented to show the superior performance in efficiency improvement, EMI reduction, and dv/dt reduction of the proposed soft-switching inverters