A Bridgeless Semi-Quadratic Gain High Power Factor AC-DC Converter Based LEVs Charging Solution

A charger topology using a single stage and transformer-less design employing bridgeless semi quadratic voltage gain with high power factor (HPF) AC-DC converter, is demonstrated in this article for light electric vehicles (LEVs). In order to achieve transformer-less structure and wide voltage gain (particularly step-down gain) between high AC input and low DC output (LEVs battery packs), an integrated structure comprising of a bridgeless SEPIC (single ended primary inductor converter) and a buck converter, is effectively utilized to achieve desired charging characteristics at the battery end and maintaining high power factor at AC end of the charger. The bridgeless along with the transformer less structure, together helps in reducing the size, and the cost of the charger and to improve its overall efficiency. Further, the discontinuous inductor current mode (DICM) operation optimizes the volume of magnetics, facilitates power factor correction inherently at the input and ensures zero current switching of semiconductor devices, without having to provide additional control or circuit modifications. This work gives a comprehensive, theoretical, and mathematical analysis of the concepts and advantages of the presented topology, with proper design of its active and passive components. Lastly, the performance of the charging circuitry is verified using a proof-of-concept hardware setup and corresponding results are discussed for performance verification. Moreover, the comparative analysis of the presented charger with state-of-art chargers and converter topologies is carried out to justify the distinctive properties of former one compared to the latter one.