ANTI-SATURATION CASCADE GENERALIZED PREDICTIVE CONTROL APPLIED IN INDUCTION MOTOR

Abstract

Owing to the physical limitations in the variable speed induction motor drives, the windup phenomenon appears and results in performance degradation when the speed controller output is saturated by the current limiter, this happens often when a large change in the speed reference occurs. This paper’s aim is to prevent the undesirable effects of the saturation controller by employing a retuned generalized predictive speed controller based on Youla parametrization. The synthesis of an initial GPC controller based on its polynomial equivalent structure is required in the first step. Then, thanks to the Youla parameterization, this controller is retuned considering these saturation constraints reflected on two specifications. The first is a frequency specification on the quadratic component of stator current response to the speed reference which assures a minimal control action in transient periods. And the second is a time domain constraint on the measured speed response to the speed reference that enforce the output response to be within an imposed envelope. These constraints are stated within a linear convex optimization problem. The simulation results proved the efficiency of the resulting predictive speed controller.

Keywords

• amplitude saturation
• anti windup controller
• generalized predictive control
• induction motor control
• youla parameterization