Direct power and torque control for three-level NPC based PWM ac/dc/ac converter

This paper presents a new control scheme for three-level neutral point clamped (NPC) based PWM AC/DC/AC converter. The direct power control (DPC) for front-end three-level PWM rectifier and direct torque control (DTC) for back-end three-level PWM 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. Simulation results show that with the proposed control scheme, the three-level NPC based PWM AC/DC/AC converter exhibits excellent dynamic performance, and can minimize DC-bus voltage fluctuations.