Sliding mode speed control of an induction motor drive using time-varying switching line

An equivalent sliding mode control method of an induction motor speed has been discussed. The control signal consists of two parts: a continuous and discontinuous one. Very good dynamical response of the drive system has been obtained, which however changes influenced by external and parametric disturbances occurring under various operation conditions. In order to ensure identical dynamic performance of the speed transients and system robustness during the switching line reaching phase, regardless of external and parametric disturbances, the time-varying switching line is proposed. The simulation results have been validated by experimental tests of the induction motor drive system.