ARCPI resonant snubber for the neutral-point-clamped (NPC) inverter

This paper reports a resonant snubber for the neutral-point-clamped (NPC) inverter using the auxiliary resonant-commutated-pole-inverter (ARCPI) technique. The proposal guarantees zero voltage switching of the main switches and zero current switching of the auxiliary switches without incurring any voltage or current spikes across or through the main switches and without subjecting to any modulation constraints. Operation principle of the ARCPI NPC inverter is illustrated. A simple method dealing with the static overvoltage problem of the inner switches is described. Commutation durations and current stresses in the basic ARCPI circuit are analyzed. The results enable mathematical understanding and practical designing of the basic ARCPI circuit. In particular, self balancing quality and controlling possibility of the DC center potential in the basic ARCPI circuit are investigated. The proposal is verified by a 3 kW half bridge ARCPI NPC inverter laboratory prototype.