DTC of induction motor based on adaptive sliding mode control

To reduce flux and torque ripple associated with traditional direct torque control (DTC) of induction motor, a new DTC based on sliding mode control is presented in this paper. An adaptive sliding mode controller is considered to replace PI controller for the outer speed loop. Furthermore, hysteresis comparators are substituted by sliding mode controllers based on torque and flux errors for the inner loop. The space vector modulation technology is used in order to maintain a fixed switching frequency of inverter. Moreover, considering the unknown load torque during the running of induction motor, the load torque observer is proposed. The simulation verifies that the designed control scheme can not only significantly reduce torque and flux ripple, but also have strong robustness.