Speed regulation of induction motors: an adaptive sensorless sliding mode control scheme

A current-based sensorless sliding mode control for induction motors is presented in this paper. It guarantees asymptotic tracking of prespecified speed and square of the rotor flux magnitude references without mechanical sensors. The problem of chattering, typical of sliding mode controllers, is overcome since the derivative of the stator currents are used as discontinuous forcing actions, while the actual control signals are continuous, thus limiting the mechanical stress. The proposed adaptive sliding mode speed observer is based on a different approach with respect to the widely used equivalent control techniques.