Analyzing stability issues in a cascaded converter system comprised of two voltage-mode controlled dc-dc converters

Abstract

This work analyzes the stability of a cascaded converter system comprised of two dc-dc converters operating with voltage-mode controllers. First it develops a single converter small-signal model and derives the mathematical representation of the converter from it. Next, it derives the required closed-loop transfer functions and input and output impedances from the model. Then, it develops the cascaded converter model based on the derived closed-loop impedances and the single converter model. Finally, it derives the cascaded converter system transfer function which addresses the stability of the system and analyzes the stability based on this transfer function.