Direct Torque Control of Reversing Voltage Topology Multi-Level Inverter Fed Induction Motor

Abstract

Variable speed induction motor drives find applications in various industries. The normal Induction Motor drive has a closed loop speed control. Here, we use a Multi- Level Inverter (MLI), which has emerged as an alternative in the medium-voltage high-power control to feed the Induction Motor. The Multi-Level Inverter employs a new topology known as the reversing voltage topology (RVT). To generate output voltage with higher number of levels, this topology requires less number of components and less carrier signals for PWM implementation. The proposed induction motor drive structure offers reduced device count and a simpler power-bus structure when compared to a conventional five-level NPC and flying capacitor inverter fed induction motor drives. The Induction Motor is controlled by the scalar method of Direct Torque Control (DTC). This scheme is the direct control of the torque and stator flux of a drive by inverter voltage space selection through a look-up table to maintain speed at reference. Performance comparison for various voltage vector selections has been made. This technique has a comparable performance with that of vector controlled drives