A comparison of direct torque control methodologies for induction motor

Direct torque control of inverter-fed induction motor allows high dynamic performance by means of very simple control schemes. In this paper various direct torque control methodologies (classical DTC, DSVM-DTC and SVM-DTC) have been analysed and compared in order to evaluate the influence of the motor operating condition on steady state performances. A particular emphasis on stator current distortion and on torque ripple has been made. Having a larger number of available voltage vector, DSVM-DTC presents smaller torque ripple than classical-DTC and shows the same flux and stator current performances. SVM-DTC achieves the best performances, but it uses more complex scheme and it depends on motor parameters. Experimental tests have been carried out in order to validate the proposed analysis