On DSP-based real time control of an induction motor using sliding mode

This paper deals with the control and observation of an induction motor using sliding mode technique. Our aim is to regulate the rotor speed and the square of the rotor flux magnitude to specified references. Assuming that all the states are measured, nonlinear sliding surfaces are used to this end. 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 uncertainty and measurement noise. For the sake of illustration we present experimental results obtained on a digital signal processor (DSP) TMS 320C31/40 MHz based system for 0.37 kW induction motor. The experimental results show that the proposed control system is robust against stator and rotor resistance variations.