Complex-order Reset Control System

TL;DR

This paper introduces a novel complex-order reset control system that approximates complex-order transfer functions to overcome Bode's gain-phase limitations, demonstrating improved control performance through simulation.

Contribution

It proposes a reset element and tuning method to approximate a complex-order controller, enabling better control performance beyond traditional linear controller constraints.

Findings

The proposed method effectively approximates complex-order transfer functions.

Simulation results show improved step response and robustness.

The approach breaks Bode's gain-phase relation limitations.

Abstract

According to the well-known loop shaping method for the design of controllers, the performance of the controllers in terms of step response, steady-state disturbance rejection and noise attenuation and robustness can be improved by increasing the gain at lower frequencies and decreasing it at higher frequencies and increasing the phase margin as much as possible. However, the inherent properties of linear controllers, the Bode's phase-gain relation, create a limitation. In theory, a complex-order transfer function can break the Bode's gain-phase relation; however, such transfer function cannot be directly implemented and should be approximated. This paper proposes a reset element and a tuning method to approximate a Complex-Order Controller (CLOC) and, through a simulation example, shows the benefits of using such a controller.