Analysis of Direct Torque Control using Space Vector Modulation for Three Phase Induction Motor

Abstract

This paper presents the results of an investigation into the suitability of a Direct Torque Control of three phase Induction motor. It is considered as an alternative to the field oriented control (FOC) or vector control technique. They aim to control effectively the torque and flux. Direct Torque Control (DTC) uses an induction motor model to predict the voltage required to achieve a desired output torque. By using only current and voltage measurements, it is possible to estimate the instantaneous stator flux and output torque. An induction motor model is then used to predict the voltage required to drive the flux and torque to the demanded values within a fixed time period. This calculated voltage is then synthesized using Space Vector Modulation (SVM). Torque control of an induction machine based on DTC strategy has been developed and a comprehensive study is described. The performance of this control method has been demonstrated by simulations performed using a versatile simulation package, Matlab.