Nonlinear servo control of an induction motor with saturation

This work is an extension of the authors´ (1994) previous work on high-performance induction motor control in which the magnetic model of the motor was assumed to be linear. Here, saturation of the iron in the main path of the induction machine is taken into account. The saturation is modeled in the dq coordinate frame and the model is then used to design an input-output linearization controller to provide independent (decoupled) control of the speed and flux. With this controller, the flux reference becomes an extra degree of freedom for the designer to help achieve performance objectives. Taking into account saturation, the flux reference is chosen to achieve the optimal torque (maximum for acceleration and minimum for deceleration) at any given speed. The input-output controller is used to provide tracking of a given position and speed trajectory while simultaneously tracking the optimal flux reference. Experimental results are given to validate the approach