Backstepping direct torque control of permanent magnet synchronous motor with RLS parameter identification

Abstract

Direct torque control (DTC) system of permanent magnet synchronous motor (PMSM) has large torque ripples and inconstant switching frequency, especially at low speed. An improved DTC method of PMSM based on backstepping control with recursive least squares (RLS) parameter identification is proposed in this paper. In this method backstepping controller is designed using PMSM mathematical models and space vector modulation (SVM) produces switching signals of inverter. In order to eliminate the effect of PMSM parameters variations on the control system, PMSM parameters are identified using RLS and are used in the backstepping controller. Simulation results show that compared to the traditional DTC, the proposed DTC based on backstepping control with RLS parameter identification could effectively decrease flux and torque ripples, and make inverters have constant switching frequency and RLS could accurately identify PMSM parameters.