Title: Adaptive backstepping control of an induction motor under time-varying load torque and rotor resistance uncertainty

Authors: Arbin Ebrahim, Gregory Murphy

Addresses: Department of Electrical and Computer Engineering, Tuskegee University, Tuskegee, AL 36088, USA. ' Department of Electrical and Computer Engineering, Tuskegee University, Tuskegee, AL 36088, USA

Abstract: A new global adaptive controller is designed for induction motor speed control based on measurements of speed and stator current. The designed partial state feedback controller is singularity free, and guarantees asymptotic tracking of smooth reference trajectories for the speed of the motor under time-varying load torque and rotor resistance uncertainty, for any initial condition. The new control algorithm generates estimates for unknown time-varying load torque, rotor resistance and unmeasured state variables (rotor fluxes) which asymptotically tracks and converges to their true values. The rotor flux modulus asymptotically tracks a desired reference signal which allows the motor to operate within its specifications. The control strategy yields decoupled rotor speed and rotor flux amplitude tracking control goals which allows the selection of an appropriate flux modulus for the rotor to maximise efficiency.

Keywords: nonlinear control; adaptive control; backstepping control; time-varying load torque; rotor resistance uncertainty; induction motors; field orientation; feedback control; rotor fluxes; tracking control.

DOI: 10.1504/IJAAC.2008.022893

International Journal of Automation and Control, 2008 Vol.2 No.4, pp.401 - 417

Published online: 02 Feb 2009 *

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