Predictive Control with Variable Amplitude of Voltage Vector of Surface PMSM Direct Torque Control System

Abstract

Based on flux and torque’s expressions of surface permanent magnet synchronous motor (PMSM) direct torque control (DTC) system, the values of stator flux and torque at next sampling point after applying voltage vector with different amplitude are given in this paper. And objective function of flux and torque’s error is proposed which only uses the amplitude of applying voltage vector as the variable. The predictive control will select the optimal voltage vector which aims to minimize objective function. Simulation results show the PMSM DTC system under the control of proposed strategy works properly. The predictive control selects the optimal voltage vector from aggregate of voltage vectors. More selectable voltage vectors will lead to better control performance, but it will cause heavier calculation burden. In this paper, control performances of surface PMSM DTC system are given using 9 aggregates of selectable voltage vectors. Considering control performance and calculation burden, dividing voltage vector into three equal parts to get 3 selectable voltage vectors is an ideal way.