Servo system design for speed control of AC induction motors using polynomial differential operator

This paper proposes a servo system designed for speed control of AC induction motors using polynomial differential operator to track more complicated types of reference speed and disturbance such as step, ramp, parabola, etc. To do this task, the followings are done. First, modeling for an induction motor is introduced and is linearized at equilibrium points using Taylor’s series. Second, observer is designed to estimate flux, and an extended system incorporating the internal model principle to construct the servo system is derived using polynomial differential operator in case that the types of reference inputs are polynomials. Third, a state feedback control law for the servo system to track the given reference input is designed. To implement the proposed controller and servo system, a control system is constructed for speed control of 1.5 Kw AC induction motor. The simulation and experimental results are conducted to verify the effectiveness and the applicability of the proposed controller compared to the conventional PID controller and MRAC controller for more complicated higher order types of the references and disturbance such as step, ramp, parabola, etc.