A large signal dynamic model for buck-cascaded Buck-Boost converter in universal-input PFC applications

This paper presents a novel model for average current control that can be applied to the buck-cascaded buck-boost converter (BuCBB) with two independently controlled switches in universal input power factor correction (PFC) circuits. The proposed BuCBB PFC model consists an averaged BuCBB topology with all the switching elements replaced by dependent sources and an average current control scheme with a pulse width modulation (PWM) model, which determines the duty cycles. The model simulation speed can be dramatically accelerated as well as the steady-state and large signal dynamic behavior of the BuCBB converter can be correctly predict. Similarly, the averaged model of other buck-boost converters having two independently controlled switches can be easily obtained by following the same principle.