Efficiency modeling and evaluation of a resonant snubber based soft-switching inverter for motor drive applications

This paper establishes an analytical model for a resonant snubber based soft-switching inverter. The model adopts the loss separation method to evaluate losses in individual components. Because of symmetry of the inverter circuit, the developed model is suitable for both single-phase and three-phase inverters. A single-phase inverter has been built and tested with a single-phase induction motor driving a fan load to verify the developed model. The equivalent single-phase induction motor model was curve-fitted from experimental results. The analytical results demonstrated reasonable agreement with the experimental results. The same efficiency evaluation method was then applied to a nonzero-voltage turn-on hard-switching inverter, and the results were compared with that of the soft-switching inverter. The resonant snubber based soft-switching inverter shows substantial efficiency improvement over the hard-switching inverter, especially in low speed operation