The method of double averaging: An approach for modeling power-factor-correction switching converters

This paper describes the modeling of power-factor-correction converters under average-current-mode control, which are widely used in switch-mode power supply applications. The objectives is to identify stability boundaries in terms of major circuit parameters for facilitating design of such converters. The approach employs a double averaging procedure, which first applies the usual averaging over the switching period and subsequently applies generalized averaging over the mains period. The resulting model, after two averaging steps and application of a harmonic balance procedure, is nonlinear and capable of describing the low-frequency nonlinear dynamics of the system. The parameter ranges within which stable operation is guaranteed can be accurately and easily found using this model. Experimental measurements are provided for verification of the analytical results.