Design of Single-Stage Light Electric Vehicles Battery Charger Based on Isolated Bridgeless Modified SEPIC Converter With Reduced Switch Stress

Abstract

An onboard charger segment is currently dominated by two-stage charger designs, which suffer from drawbacks such as large size, low efficiency due to a high component count, elevated cost, and intricate controller requirements. To address these challenges, this work explores the implementation of an isolated bridgeless version of a modified single-ended primary inductor converter (SEPIC). This innovative approach aims to develop a single-stage, high-power factor battery charger tailored for light electric vehicles (LEVs). In addition to achieving high power factor operation, maintaining continuous input and output currents, and enabling high voltage conversion ratios, this charger utilizing modified SEPIC converter is specifically engineered to alleviate voltage stress on power switches within the converter circuit. This charger operates in discontinuous conduction mode (DCM), offering several notable advantages. These include inherent power factor correction capability, reduced control effort, minimized size of magnetic components, and fewer sensors, ultimately leading to a significant reduction in overall implementation cost. This article aims to validate charger's operation, elaborate on design of its components, outline control algorithm design, and demonstrate performance of both components and control logic through test results from hardware prototype developed, for a power level of 500 W.