Impedance-Based Stability Analysis for Interconnected Converter Systems With Open-Loop RHP Poles

The small-signal stability of interconnected converter systems can be tackled by the impedance-based analysis method, where the Bode plots of the individual impedances derived from subsystems are utilized for a design-oriented analysis. However, those methods only apply to the interconnected systems without having open-loop right-half-plane (RHP) poles. This article thus proposes a general stability analysis method based on Bode plots of individual impedances, which allows considering the open-loop RHP poles and shaping the impedances for stabilizing the system. Experimental case studies on the current control interactions of two paralleled grid-tied inverters validate the effectiveness of the method.