Voltage vector selection strategy of the DTC for SPMSM based on predictive control

Abstract

In this paper, voltage vector selection for the direct torque control (DTC) for surface permanent magnet synchronous motor (SPMSM) based on predictive control is proposed. Firstly, based on increasing or decreasing effects of the applying voltage vector on the amplitude of stator flux and torque of SPMSM, the proper voltage vector selection area of the DTC for SPMSM is given. Then predictive control is used to determine the angle of applying voltage vector in voltage vector selection area. A cost function of stator flux and torque's errors is proposed to evaluate the performance of different angle of applying voltage vector whose amplitude is constant. The angle which results in the minimum cost function among different angles is selected as the angle of the applying voltage vector. As the applying voltage vector is selected from proper voltage vector selection area, it can always satisfy the control of stator flux and torque. Finally, space vector modulation (SVM) is used to generate the applying voltage vector. Simulation results show the DTC for SPMSM works properly under the proposed control strategy. Compared with conventional switching table, the proposed strategy can suppress torque ripple and reduce cost function and mean squared error of torque and stator flux. And due to the use of SVM, switching frequency is kept constant.