Bridgeless Modified High-Step-Up Gain SEPIC PFC Converter Based Charger for Light EVs Battery

This study presents a two-stage on-board charger for light electric vehicles (LEVs) with low voltage battery (24–72 V). The front-end of the charger has characteristics of high voltage conversion ratio and unity power factor operation achieved by a bridgeless high gain modified SEPIC converter. The high voltage conversion ratio enables the front-end to operate over a wide range of input voltages. At the back-end of the charger, an isolated positive output Luo DC-DC converter is employed to regulate the charging profile of the LEV battery under constant current (CC) and constant voltage (CV) charging modes. The presented charger operates in discontinuous conduction mode (DCM), which has dual advantages of having inherent feature of power factor correction (PFC) at the supply end along with significantly reducing the complexity of control mechanism, thereby reducing the cost and effort of control implementation. The operational analysis and design of the presented charger in DCM are covered in detail in this study and the same are further validated by means of simulations. A 650 W test bench setup is developed to authenticate the theoretical performance by means of experimental results. The experimental performance of the front-end is finally compared with other PFC topologies to highlight the merits and demerits of the presented charger.