A Modified Direct Toque Control for Interior Permanent Magnet Synchronous Motor Drive Without a Speed Sensor

Direct torque control (DTC) can produce quick and robust response, but it has the problems of large torque ripples and inconstant inverter switching frequency. This paper introduces a modified direct torque control based on the space vector pulse width modulation (SVPWM) for interior permanent magnet synchronous motor (IPMSM) drive without a speed sensor. Two PI controllers regulate the flux and torque respectively and the inverter is controlled by the SVPWM technique in the proposed DTC system. Speed estimator is based on the model reference adaptive system (MRAS). Simulation results show that the performance of the proposed DTC system has been improved with respect to the conventional DTC. The DTC system can effectively reduce the flux and torque ripples and speed estimator can accurately track the speed of motor