Modelling of Fractional-Order System in Complex Domain Using Direct Approach: A Comparative Study

In this paper, a class of fractional-order system (FOS) has been modelled in complex \(z\) -domain through direct discretization of the fractional-order (FO) operator. Two generating functions, namely Visweswaran–Varshney–Gupta–Schneider (VVGS) transform and reduced Ngo transform, have been employed to obtain the approximate discrete-time models of the FO operator via continued fraction expansion (CFE) method. The stability analysis is performed through determining the pole locations of the discretized fractional-order systems. Finally, the two transforms have been compared based on the simulation outcomes obtained from the frequency responses of the approximated fractional-order systems.