An Effective SPWM Control Technique for 1MVA 6000V Cascaded Neutral Point Clamped Inverter

Cascaded neutral point clamped (NPC) inverter is more suitable for high voltage, high power applications, but the power and voltage balances are crucial in practical uses. This paper proposes an effective SPWM control scheme for a cascaded NPC inverter in which a pulse rotation is fulfilled for all modulation indices. The module voltage and power, and series- capacitor voltage of each module are perfectly balanced, and each module has low switching frequency providing high pulse frequency of phase voltage. The proposed scheme is applied to the 1M VA 6000 V 17-level cascaded NPC inverter for an 800 kW 4160 V induction motor drive. The experimental results verify the proposed scheme.