Implementation of a direct control algorithm for induction motors based on discrete space vector modulation

The basic concept of direct torque control of induction machines is investigated in order to emphasize the effects produced by a given voltage vector on stator flux and torque variations. The low number of voltage vectors which can be applied to the machine using the basic DTC scheme may cause undesired torque and current ripple. An improvement of the drive performance can be obtained using a new DTC algorithm based on the application of the space vector modulation (SVM) for prefixed time intervals. In this way a sort of discrete space vector modulation (DSVM) is introduced. Numerical simulations and experimental tests have been carried out to validate the proposed method.