Performances of DTC system fed by a three-level NPC VSI

This paper presents a performance of three-level inverter Neutral Point Clamped (NPC) structure fed induction machine. The proposed topology is an emerging technology and is commonly applied to high power motion drives instead of the standard two-level voltage source inverters (VSI). However, it has an inherent problem of neutral point potential variation. In this way, a Direct Torque Control (DTC) technique has been applied and the estimated value of the Neutral Point Potential (NPP) is used, which is calculated by machine currents. This control strategy uses the redundancy presented by the inverter for selecting appropriate switching state through an switching table to achieve the control of NPP. This study shows the effect of the stability problem of the DC voltages and good static and dynamic performances were obtained in simulation.