An extended and improved discrete space vector modulation direct torque control for induction motors

In the classical DTC scheme, due to the limited number of the VSI voltage vectors, large and small errors can not be distinguished. In fact, the switching vectors chosen for large errors are the same as those chosen for small errors. In this paper, in order to overcome this problem, after considering the primary ideas of the DSVM-DTC technique, a new approach for the realization of the DSVM-DTC methodology of the induction machine is proposed. The proposed method, along with its simplicity, has an improved performance in terms of the torque and the current ripple and can be easily extended. In addition, it minimizes the steady state torque error. By using the proposed DSVM-DTC methodology, the six nonzero voltage vectors of the standard VSI topology are divided into equal fractions and a fraction of these vectors is applied to the motor depending on the amount of the torque error and in accordance with the classical DTC scheme basics. Numerical simulations and experimental tests have been carried out to validate the proposed technique.