Sliding mode control of an induction motor with unknown load: Application on a digital-signal-processor-based system

Abstract

In this paper we propose a two stage sliding mode control of an induction motor with unknown load. Firstly, given the desired rotor speed trajectory omega ref, the underlying reference torque T is calculated for the generated torque Te. In the second stage, ref two sliding surfaces are proposed to track the reference torque and flux trajectories. The stator voltages are derived so that the sliding surfaces are asymptotically attractive. Since in practice the rotor fluxes are not usually measurable and the load torque is unknown,a sliding modeobserver is derived to estimatetherotor fluxes and an adaptive control law is proposed to estimate the load torque. For illustration we present experimental results for a 0.37 kW induction motor obtained for a system based on a digital signal processor TMS 320C31 (40 MHz).