Performance improvement of induction motor by using direct torque control technique

Direct torque control (DTC) of induction machine is known to have a simple control structure with comparable performance to that of the field-oriented control technique. Major problems that are usually associated with DTC drives is high torque ripple. In this paper torque ripple of the induction motor is reduced. This torque ripple is reduced by adding dither signal in to the torque and flux control loop. A conventional DTC control of three phase induction motor is modified by injecting high frequency and small amplitude triangular waveform in to torque and flux error. This effectively increases the switching frequency of the inverter. It is observed that the torque ripple is reduced and performance get improved. The simulation results are provided to validate the proposed dithering technique in DTC controlled three-phase induction motor.