A Unique Model of Switching Converters for SPICE

In this paper, a unique switching converter model, the SCM subcircuit, is developed to replace two linear switching networks that a converter goes through in each switching cycle. A state space averaging method and a describing function technique are employed to establish small-signal models for the switching converter, multiloop error processor and duty-cycle pulse with modulator. On the basis of these models, a "Switching regulator ANalysis program", called SWAN, is developed. The program SWAN can be used to examine various small-signal open-loop or closed-loop performances of the switching regulators. This paper presents the analysis curves of a real current-injected control regulator, which are very close to the experimental measurement. The paper also shows how to link SWAN to SPICE, a widely used GAD package for electronic circuits.