Fast-scale instability of singlestage power-factor-correction power supplies

Abstract—This paper describes the fast-scale bifurcation phe-nomena of a single-stage power-factor-correction (PFC) power supply which is a cost effective design for 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. Main results are illustrated by “exact ” circuit simulations as well as theoretical analysis based on the use of Jacobians. This work provides a convenient means of predicting stability boundaries which can facilitate the selection of practical parameter values for maintaining stable operation. Index Terms—Bifurcation, dc–dc converter, instability, power factor correction (PFC), single-stage converter. I