Novel nonlinear representation for two-stage power-factor-correction converter instability

Two-stage power-factor-correction (PFC) converter is the most common circuit to draw sinusoidal and in phase current waveforms from the ac source with a good regulated output voltage. The first stage is the boost PFC converter with average-current-mode control for achieving the near-unity power factor and the second stage is the forward converter with voltage-mode control for the purpose of a regulated output voltage. Stability analysis and design method were discussed depending on the linear models. Recently, new; nonlinear phenomena have been detected in PFC circuits and a new nonlinear model has been proposed for the pre-regulated PFC converter. Therefore, this paper introduces a study for stability of two-stage PFC converter. A novel nonlinear model for two-stage PFC converter is proposed. Then, stability analysis is studied depending on this nonlinear model. Simulation and experiment confirm this analysis with a good matching.