Isolated Power Factor Corrected High-Gain AC-DC Buck-Boost Converter Based Single Stage LEV Battery Charger

This study presents an isolated single-stage high power quality battery charger for light electric vehicles (LEVs) based on a high step-down gain AC-DC buck-boost converter. The presented charger offers several advantages over the conventional two-stage charger, some of which are reduction in overall component count, reduced cost and size, elimination of large DC Link capacitor, reduction in control effort, and better dynamic voltage regulation. The size and cost of the charger are further diminished by designing the converter in discontinuous conduction mode (DCM). This also allows to reduce the control effort and the number of sensors required for the single-stage charger when compared to continuous conduction mode (CCM) and leads to simpler implementation of constant current (CC) and constant voltage (CV) methodologies of battery charging. Additionally, the charger also exhibits features like high voltage conversion ratio and high power factor operation. The inclusive efficiency of the presented charger is improved by using the converter in its bridgeless form, which significantly reduces the conduction losses accompanying the full bridge diode rectifier (DBR). This study validates feasibility of the charger and its performance during both steady and dynamic states by simulations for a 450 W charger.