Model predictive direct torque control for SPMSM with load angle limitation

Abstract

The purpose of this paper is to describe a model predictive direct torque control (MPDTC) with load angle limitation for surface-mounted permanent magnet synchronous motor (SPMSM) drive system. In this paper, an exact discrete-time state-space model of SPMSM is presented, which improves the state prediction accuracy comparing to simple Euler approximation. A finite control set type MPDTC is used to select the optimum voltage vectors applying to the voltage source inverter (VSI). It makes full use of the inherent discrete nature of VSI, and according to the predefined cost function it chooses the optimal solution from the possible switching states. It has been found that with the proposed scheme SPMSM drives show adequate dynamic torque performance and considerable torque ripple reduction as compared to traditional direct torque control (t-DTC). With the load angle limitation in the cost function, the proposed scheme can prevent the PMSMs falling from synchronism.