Realization of New Robust Digital Fractional-order Compensators

Abstract

The efficient and robust realization of fractional-order compensators is fundamental for digital control applications. The main task is to approximate these devices with an efficiently computed rational transfer function with limited negative effects due to quantization and other implementation issues. This paper proposes new closed-form expressions to easily determine the coefficients of the discrete transfer functions. Moreover, a realization with low sensitivity is obtained by the serial structure of a multiple compensator that employs adjacent, shifted sections, each dominating on a different frequency interval and contributing to a flat Bode phase diagram. The achieved features are useful for designing robust controllers.