Average small-signal analysis of power factor correctors controlled by conduction angle

This paper deals with the obtaining of the average small-signal model for power factor correctors (PFCs) controlled using a recently proposed control method for this type of converters. This new control method is based on controlling the conduction angle (CA) of the input current and it can be implemented in an extremely simple way, since an inexpensive bipolar transistor (or even the optocoupler used in the output-voltage feedback loop) can be used to shape the line current. This method is simpler and cheaper than the one based on using a multiplier, which makes it very attractive for low-cost PFCs. The model obtained is applicable for frequencies below the line frequency, and it is useful for designing the low-frequency compensation network for the output-voltage feedback loop. Finally, this model has been verified by both simulation and experimental results.