Maximum sensitivity based parameters tuning of fractional-order PI^λ controller for time-delay systems

How to obtain robust stability has always been a key issue in practical time-delay applications, and a fractional-order controller is gradually employed for time-delay system due to its flexibility. For systems with time delay or uncertain factors, D-decomposition technology is commonly applied to the parameters tuning of fractional-order PI^λ D^μ controllers. Considering the large parameter regions obtained by D-decomposition technology, an improving tuning method of fractional-order PI^λ controller for time-delay systems based on maximum sensitivity is proposed, so as to enhance the close-loop robustness. Firstly, larger stabilizing regions of fractional-order PI^λ controllers are calculated based on the D-decomposition technology, then the stabilizing regions are shrink into smaller ones through the maximum sensitivity curve defined in this paper. To verify the effects of the proposed tuning method, a simulation of a common time-delay system with step response and disturbance response is conducted. Moreover, as a typical time-delay plant, permanent magnet synchronous motor is considered in experiment to verify the proposed method. Both the simulation and experiment results show that the dynamic performance and disturbance rejection of the controlled system are improved by the proposed method.