Real-time sliding-mode observer and control of an induction motor

This paper deals with the control and observation of an induction motor using sliding-mode technique, Our aim is to regulate the speed and the square of the rotor flux magnitude to specified references, Assuming that all the states are measured, sliding surfaces are proposed within a sliding-mode control framework. Then, the stator voltages are derived such that the sliding surfaces are asymptotically attractive. Since, in practice, the rotor fluxes are not usually measurable, a sliding-mode observer is derived to estimate the rotor fluxes. Furthermore, it is shown that our observer is robust against modeling uncertainties and measurement noise. To illustrate our purpose, we present experimental results for a 0.37-kW induction motor obtained on a digital-signal-processor-based system (TRIS 320C31/40 MHz). The experimental results show that the proposed control system is robust against rotor resistance variations.