A fixed switching frequency predictive torque control scheme for induction motors based on discrete space vector modulation

Abstract

In this paper, a novel constant switching frequency technique based on discrete space vector modulation is proposed for predictive torque controlled induction motors. As known, the discrete space vector modulation (DSVM) technique considers virtual voltage vectors, which are a sequence of real voltage vectors, and applies them to the power converter in fixed time intervals. Instead of the real voltage vectors, these virtual voltage vectors could be evaluated in the predictive torque control (PTC) algorithm. This approach is called PTC-DSVM in this paper, in which the predictive algorithm selects the optimum sequence of the real voltage vectors. The proposed constant switching frequency technique determines the appropriate application order of voltage vectors in sequences, so that fixed switching frequency is guaranteed, while the performance of the proposed method in tracking the control objectives is retained respect to conventional PTC. Moreover, no extra computational burden is imposed on the control algorithm. Finally, experimental tests are carried out to confirm the validity of the proposed method and its advantages.