Fuzzy direct torque control of induction motor with sensorless speed control using parameters machine estimation

Direct Torque Control (DTC) is a method, which is used to control the flux and torque of a motor. This method uses a flux and torque estimator and two hysteresis controllers. The major problem that is usually associated with DTC drive is the high torque ripple. The stator resistance is used in the flux and torque estimator. So the stator resistance deviation from its set value, might affect fuzzy-DTC performance especially at low speed. To overcome these problems, this paper presents an improved direct torque control based on fuzzy logic technique, where the torque and flux hysteresis controllers are replaced by fuzzy controllers and we also used a fuzzy stator resistance estimator The fuzzy proposed controller is shown to be able to reducing the torque and flux ripples and to improve performance DTC especially at low speed.