Evaluation of soft switching techniques for the neutral-point-clamped (NPC) inverter

This paper evaluates the topological variants of the soft switching NPC inverter based on the resonant pole techniques. Conventional dissipative and regenerative snubbers as well as soft switching techniques for NPC inverter discussed in the past decade are reviewed first. The auxiliary-resonant-commutated-pole-inverter (ARCPI) is compared to a newly proposed transformer assisted resonant pole inverter next. Both techniques are extended to NPC inverter and multilevel inverter, the features of the resultant soft switching schemes are identified and compared. Experimental results from a 7 kW half-bridge transformer assisted PWM zero voltage switching NPC inverter are given in the end.