A Nonlinear Tracking Controller for Voltage-Fed Induction Motors With Uncertain Load Torque

In this paper, a new adaptive output feedback control scheme for the full-order (voltage-fed) model of the induction motor is presented. The proposed algorithm uses measurements of the stator currents and rotor speed and achieves global asymptotic convergence of the rotor speed and flux magnitude to their desired (time-varying) references. The distinguishing feature of the proposed scheme, which makes it appealing from a practical viewpoint, is that it consists of a simple output feedback control law, which is derived using standard arguments pertaining to Hamiltonian systems and passivity-based control. In order to make the scheme robust to load torque variations, an adaptation mechanism is added, which yields asymptotic estimates of the unknown load torque, and a rigorous stability proof for the resulting cascaded closed-loop system is provided. The efficacy of the proposed controller is verified via simulations and experimental tests.