Dynamic Modeling of Differential DC-DC Converters Using Thévenin Equivalent Circuit

This paper presents an approach to obtain dynamic models of differential DC-DC converters based on Thévenin equivalent circuits. A differential converter is based on the connection of two DC-DC converters, in which the output voltages are respectively positive and negative concerning a common terminal. Thus, any load connected between these positive and negative terminals is subjected to a voltage equivalent to the difference in the output voltages of each converter. As the number of energy storage elements is one of the factors influencing the modeling efforts, it is evident that the modeling of differential converters may involve a substantial algebraic complexity since the connection of two second-order primary converters results in a fourth-order differential converter, for example. As an alternative to simply the complexity during the modeling stage, this paper introduces a methodology based on the Thévenin equivalent circuit, in which the small-signal model of a differential converter is obtained from the Thévenin equivalent circuits of the primary associated converters. The proposed methodology is introduced and exemplarily applied to obtain the oriented-control transfer function of eight DC-DC differential converters. Simulation results are presented to validate the theoretical analysis.