An adaptive sliding mode control law for induction motors using field oriented control theory

In this paper, an indirect field-oriented induction motor drive with a sliding-mode controller is presented. The proposed sliding-mode control law incorporates an adaptive switching gain that avoid calculating an upper limit of the system uncertainties. The design also includes rotor speed computation from measured stator terminal voltages and currents. The calculated speed is used as feedback in an indirect vector control system achieving the speed control without the use of shaft mounted transducers. Stability analysis based on Lyapunov theory is also presented, to guarantee the closed loop stability. Finally simulated results show on the one hand that the proposed controller with the proposed estimator provides high-performance dynamic characteristics, and on the other hand that this scheme is robust with respect to plant parameter variations and external load disturbances