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

Dong Dai, Shengnan Li, Xikui Ma, Chi Kong Tse

Research output: Journal article publicationJournal articleAcademic researchpeer-review

43 Citations (Scopus)


This paper reports slow-scale instability in a single-stage power-factor-correction (PFC) power supply, which is a popular design solution 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 (DCM), to provide input PFC and tight output regulation. Main results are given by "exact" cycle-by-cycle circuit simulations. The effect of the slow-scale instability on the attainable power factor is illustrated in terms of total harmonic distortion which can be found by taking the fast Fourier transform of the input current. The slow-scale instability usually manifests itself as local oscillations within a line cycle. Based on the critical condition of DCM for the buck converter, the underlying mechanism of such instability is further investigated. It has been found that border collision is the underlying cause of the phenomenon. Moreover, it has been shown that the border collision observed here is effectively a nonsmooth Neimark-Sacker bifurcation. Finally, experimental results are presented for verification purposes.
Original languageEnglish
Pages (from-to)1724-1735
Number of pages12
JournalIEEE Transactions on Circuits and Systems I: Regular Papers
Issue number8
Publication statusPublished - 1 Aug 2007


  • Border collision
  • Instability
  • Power-factor correction (PFC)
  • Single-stage PFC power supply

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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