Reduced integer order inverse controller design for single fractional pole model

Abstract

In this study, we propose a method to design a reduced integer order inverse controller for single fractional order pole model. In this methodology, the inverse of the integer high order approximation of the fractional order model is taken into consideration. In order to have a feasible and applicable controller structure, this high order controller is reduced in such way that dominant poles and zeros of the approximate integer order transfer function of the system should be active. The closeness of the poles and zeros to each other and their closeness to the origin are basic dominance criteria for the order reduction. Then, the parameters of the controller are obtained depending on the fractional system parameters. The proposed controller possesses only a single design parameter which is the controller gain. The results of simulation examples show that the proposed controller performs as good as fractional order PID and classical integer order PID controllers which have five and three design parameters, respectively.