Design Procedure for a Digital Proportional-Resonant Current Controller in a Grid Connected Inverter

This paper presents a design procedure for a digital Proportional-Resonant (PR) current controller in a Grid Connected Inverter (GCI). The procedure describes a systematic list of how to compute the proportional and resonant gains as well as the coefficients for the digital resonant path. The main contribution of the design procedure is to facilitate and to support researchers who are designing GCI with current control strategies in a digital environment. The paper also presents a frequency domain analysis of a designed digital PR controller. The fictitious w-domain is used in such analysis. A case study shows the efficacy of GCI with a digital PR current controller designed based on the proposed procedure. Later, the paper discusses that the proposed procedure is valid also for digital PR controller with multiple resonant paths.