Integrated Approach to Design and Implementation of a Single-Phase Current Regulator With Antiwindup Mechanism

Abstract

An ac-regulated single-phase inverter operating in the stationary frame is designed to accurately track a sinusoidal reference signal at a designated frequency. To achieve such a control objective, resonant controllers with a conjugate set of marginally stable poles are required. The explicit implementation of marginally stable dynamics is prone to wind up in the event of the control signal entering a nonlinear saturation condition, resulting in a degraded or even an unstable dynamic response. This article proposes an integrated approach to the design and implementation of a resonant controller for a single-phase current regulator with an intrinsic antiwindup mechanism. The proposed method utilizes a disturbance observer to embed a pair of complex poles into the controller, leading to accurate tracking of a sinusoidal reference signal. Simultaneously, by using the observer architecture with a set of desired closed-loop poles as the performance specification, the implementation form remains completely stable. Furthermore, the closed-loop performance of the proposed resonant control system is analyzed to assess the impact of unmodeled dynamics. Experimental results are presented to demonstrate the efficacy of the proposed approach.