A novel control scheme for three-level NPC back-to-back converter

This paper presents a novel control scheme for three-level neutral point clamped (NPC) back-to-back converter. The distribution and balance of instantaneous energy for the converter is analyzed, and the direct power control with space vector modulation (DPC_SVM) for front-end rectifier and rotor field oriented control (FOC) for back-end inverter-fed induction motor are adopted respectively. A power feed-forward control loop from inverter to rectifier side is introduced to obtain better dynamic performance for the DC-link. Experimental results show that with the proposed control scheme, the three-level NPC back-to-back converter exhibits excellent dynamic performance, and can minimize DC-bus voltage fluctuations with low size of DC-bus capacitors.