Enhanced direct torque control of permanent magnet synchronous motor using sliding mode control theory

Abstract

The direct torque control (DTC) was proposed as an alternative to the vector control in the middle of 1980s for AC machines control. This strategy is based on the direct determination of inverter switching states and offers a simpler scheme and less sensitivity to machine parameters. However, the variable switching frequency of DTC causes high flux and torque ripples which lead to an acoustical noise and degrade the performance of the control technique, especially at low-speed regions.