Speed regulation of induction motors: a sliding mode observer-differentiator based control scheme

A current-based output feedback sliding mode control for induction motors is presented. It guarantees asymptotic tracking of prespecified speed and square of the rotor flux magnitude references, in spite of the presence of an uncertain, even time-varying, load torque, and of an unknown constant value of the rotor resistance. The control algorithm is based on a sliding mode differentiator which provides a noiseless speed signal time derivative. 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