Speed Sensorless Direct Toque Control of Interior Permanent Magnet Synchronous Motor Drive Based on Space Vector Modulation

To solve the problems of large flux and torque ripples and inconstant switching frequency in direct torque control (DTC) for permanent magnet synchronous motors (PMSM) and to eliminate speed sensor since it deteriorates system reliability and increases the cost of system, a novel speed sensorless DTC method based on space vector modulation (SVM) is proposed in this paper. This method is based on the PMSM models in the coordinate of stator flux linkage, flux and torque are controlled through stator voltage components in stator flux linkage coordinate axes and space vector modulation is used to control inverters. The instantaneous stator flux angle and load angle are calculated to estimate the motor speed. Simulation and experiment results verify that this proposed sensorless DTC scheme could effectively decrease flux and torque ripples, make inverters have constant switching frequency and the speed estimation method could accurately track the motor speed and has good dynamic and static performance.