A control scheme for three level inverter

In this paper a control strategy for a three-level neutral point clamped inverter (NPC) is described on the assumption that the inverter feed an induction motor drive with vector control. In the NPC inverter, the three level pulse width modulation (PWM) techniques based on the sine triangle FWM and space vector modulation are used to drive the induction motor. A model of induction machine is developed so that the d-axis is always aligned with the rotor flux-linkage space vector such that the rotor flux linkage in the q-axis is zero. The purpose of the proposed control strategies is to achieve an adjustable-speed drive. Simulation is supplied to confirm the validity of the proposed method.