Resonant Controllers Design for Frequency-Selective Impedance Controlled DC Microgrids

Abstract

The resonant-type controllers are commonly used in dc microgrids in order to suppress the steady-state ripples of a microgrid s dc bus voltage. As the resonant controllers are prone to cause instability issues and anomalous peaks in closed-loop frequency responses, it is of particular importance to investigate it thoroughly for the frequency-selective impedance controlled (FSIC) dc microgids, where the cascade of the resonant-type controllers is used in control of the interfacing power converters to reduce the bus s impedance at the selected frequencies. In this paper, based on the Nyquist plots analysis results, design of the FSIC resonant controllers is carried out and a step-by-step design procedure is proposed to ensure stability and no impedance peaking nearby the FSIC s frequencies. The proposed design is verified through the experiments.