Modified load angle Direct Torque Control for sensorless induction motor using sliding mode flux observer

Abstract

Direct Torque Control is a control technique in AC drive systems to obtain high performance torque control. The conventional DTC utilizing hysteresis comparators suffers from high torque ripples and variable switching frequency. The most common solution to those problems is to use the space vector modulation. In this paper a modified direct torque control of induction motor scheme is presented. The modifications include torque and flux ripples reduction. This technique is known as SVM-DTC. It is based on stator flux orientation and space vector modulation (SVM). In the other hand this paper aims to design a sliding mode observer for speed/flux estimation which improves the control performances by using a sensorless algorithm in order to decrease the cost and reliability of the system. The theoretical principles, simulation and experimental results of sensorless control method are presented using Matlab/Simulink with real time environment using dSpace 1104.