General-purpose computation of frequency characteristics of power conversion system for stability analysis by the impedance method

Abstract

Stability analysis is necessary for designing power conversion systems to ensure proper execution of the designed operations. The impedance method is useful for the analysis and it requires input or output frequency characteristics of converters that are often difficult to derive manually and analytically. This paper proposes an automatic formulation and analysis method, which utilizes a general-purpose simulation algorithm for the frequency analysis of an averaged power converter, based on connection and model information of circuit and control elements. This method is generally applicable even to a converter with nonlinear elements, such as a multiplier as far as the objective system can be linearized at the operating point. As application examples, a buck converter and a grid-forming inverter with power control are analyzed for the frequency characteristics of input or output impedances, which are utilized for stability analysis by the impedance method.