An Improved SEPIC PFC Converter for Electric Vehicle Battery Charger

This paper deals with an improved front-end SEPIC (Single-Ended Primary Inductance) converter at the input of an electric vehicle (EV) charger for power factor correction (PFC) at AC mains. Over the conventional SEPIC PFC converter, the main advantage of this converter comes with the reduction in semiconductor switch voltage for the similar output voltage. This implies that for proposed converter, same output voltage is produced at lower duty cycle. This makes the proposed converter suitable for high power rating EV chargers as the switch conduction loss is considerably reduced due to lower duty cycle. This results into overall improved efficiency of the charger. The converter is designed to operate in discontinuous conduction mode in order to achieve soft switching for switches and diodes. This PFC converter is cascaded to a DC-DC converter topology to control the current through the battery during charging process. To ensure the built-in PF (Power Factor) correction characteristics as well as to conform the IEC 61000-3-2 guidelines, tests are conducted to charge an EV battery using a prototype. The performance of this converter is found satisfactory during steady state and sudden transients in input voltage with an increased gain and reduced switch voltage stress over conventional one.