Adaptive Output Feedback Speed Control of Induction Motors with Uncertain Rotor Resistance and Load Torque

Abstract

In this paper, we propose a nonlinear adaptive output feedback control for current-fed induction motors with unknown load torque and rotor resistance. The proposed adaptive observer generates estimates both for the unknown parameters (load torque and rotor resistance) and for the unmeasured state variable (rotor fluxes); they converge to the corresponding true value under persistency of excitation which actually holds in typical operating conditions. The desired speed and flux should are assumed to be a smooth bounded function. The proposed controller guarantees speed tracking and bounded signals for every initial condition of the motor. Simulations show that all estimation errors tend quickly to zero so that high tracking performances are achieved both for speed and rotor flux.