Fast-scale instability of single-stage power-factor-correction power supplies

This paper describes the fast-scale bifurcation phenomena of a single-stage power-factor-correction (PFC) power supply which is commonly used in low power applications. The circuit employs a cascade configuration of a boost converter and a forward converter, which share an active switch and operate in discontinuous conduction mode, to provide input PFC and tight output regulation. The main findings are illustrated by computer simulations as well as theoretical analysis. This work provides a convenient means of predicting stability boundaries which can facilitate the selection of practical parameter values for maintaining stable operation.