Performance evaluation of an induction motor drive with direct torque control for open-end winding and cascaded three-level topologies

The advantages of using Direct Torque control (DTC) vis-a-vis Volt/Hz and Field Oriented Control (FOC) for the control of Induction Motor are well documented in the literature. It is also fairly well known that the performance of any AC motor drive is enhanced, when it is fed with multilevel inverters compared to the conventional two-level inverters. In this paper, the results of comparative analyses are reported when an induction motor is driven with 3-level inverters realized by (i) a three-level Cascaded Inverter and (ii) a dual-inverter driven Open-End Winding configuration. The performance indices considered are: a) THD in current b) flux-ripple and c) torque-ripple. To assess the benefit obtained by the employment of each approach, the results are compared with the performance of a 2-level Voltage Source Inverter employing classical DTC.