Single phase AC inverter current PR control with auxiliary PI controller for DC current suppression

This paper presents the design of a current control system for a single-phase grid-tied inverter equipped with a LCL grid-side filter, which is suitable for inverter DC current component suppression. For that purpose, a proportional-resonant (PR) controller of principal harmonic current component has been designed. This is followed by the design of DC current component estimator based on second-order generalized integrator (SOGI) concept, which is used for DC current suppression by means of a dedicated proportional-integral (PI) controller. Both the PR and PI controllers are designed based on the damping optimum criterion, which results in straightforward analytical expressions for controller parameters. The effectiveness of the proposed dual-current controller-based system is verified by means of simulations.