Adaptive output feedback tracking control for induction motors with uncertain load torque and resistances

The problem of guaranteeing rotor speed and flux modulus tracking on the basis of rotor speed and stator currents measurements is addressed and solved for induction motors with uncertain constant load torque and stator and rotor resistances. A new nonlinear adaptive control algorithm is designed, which relies on a closed loop adaptive observer providing estimates for the unmeasured state variables and for the uncertain parameters. Local exponential stability of the origin of the closed loop tracking and estimation error dynamics is guaranteed under persistency of excitation conditions and under suitable assumptions imposing a sufficiently slow adaptation for the stator resistance estimate.