Research on the direct torque control for asynchronous motor based on the sliding mode variable structure control

Aimed at the problems of larger torque ripple and unconstant inverter switch frequency in the direct torque control for asynchronous motor this paper puts forward a control scheme which combined sliding mode variable structure theory with Space Vector PWM technology (SVPWM) to reduce torque ripple and keep switch frequency constant. The sliding mode variable structure controller is designed based on flux error and torque error, to make the torque and flux fast and accurate adjustment, controller outputs get inverter switch pulse signal by implementing SVPWM modulation which realized the constant frequency inverter switch. The simulation results showed the effectiveness of the proposed scheme.