DTC based on SVM for induction motor sensorless drive with fuzzy sliding mode speed controller

Direct Torque Control (DTC) is known to produce quick and robust response in ac drives. However, during steady state, torque, flux, and current ripples occur. They are reflected in flux and torque estimation, and also in speed response. In this paper, a DTC based on Space Vector Modulation (SVM) for Induction Motor (IM) sensorless drive with Fuzzy Sliding Mode Speed Controller (FSMSC) is presented. The proposed control system is able to reduce the torque, flux, current, and speed pulsations during steady state. The rotor speed and stator flux are estimated by the model reference adaptive system (MRAS) scheme which is determined from measured terminal voltages and currents. The FSMSC is used in order to increase the performances and the robustness of the speed closed loop. The DTC transient merits are preserved, while better quality steady-state performance is produced in sensorless implementation for a wide speed range. The performance of the drive system has been verified by simulation tests, and good results have been achieved in both steady-state and transient operating conditions. It is concluded that the proposed control system produces better results for steady-state operation than the classical DTC.