Identification of bifurcation parameters in switching power converter composed of cascade two-stage PFC circuit

This paper is concerned with the study of bifurcation behavior of two-stage power-factor-correction (PFC) converter as an example of switching power converter. Two-stage PFC circuit is a nonlinear circuit due to the nonlinearity of the first stage boost PFC converter with average-current-mode control and the interference of the second stage DC/DC converter. However, most of previous researches design it based on small-signal analysis (linear models). In this paper, a new low-frequency (line) instability has been detected and identified in PFC circuit. The essential techniques for capturing these phenomena on the computer and laboratory are explained. It is cleared that feedback gains of the first stage PFC and the second stage DC/DC converters are large contribution parts of the total system stability.