IMPROVED ON-BOARD CHARGING ARCHITECTURE WITH LOW DC-LINK CAPACITANCE FOR ELECTRIC VEHICLES

Abstract

With the rise of Electric Vehicles (EVs), there is a growing need for efficient, compact, and high-performance battery charging systems. Typically, conventional onboard chargers have high conduction loss, large DC-link capacitors, low power density and complicated converter structure which decreases the charging efficiency and system cost. This project aims to address these drawbacks by presenting a High-Efficiency On-Board Charger for Electric Vehicles (EV) based on a Bridgeless Power Factor Correction (PFC) converter with reduced DC-link capacitance. The proposed charger is aimed to improve the charging performance, power quality and reduce the component count without compromising reliable battery charging operation. The proposed architecture is a Bridgeless Zeta PFC converter followed by DC-DC buck converter. The Bridgeless Zeta converter is a novel converter that removes the traditional diode bridge rectifier resulting in lower conduction losses and higher conversion efficiency. The converter works in Discontinuous Conduction Mode (DCM) that simplifies control strategy and also number of sensing elements required. In addition, the system operates at a high DC-link voltage of about 400 V, allowing to reduce the capacitance of the DC-link and thus to reduce the size and weight of the charger. DC-DC Buck converter is used to control the battery charging under the CC and CV modes for safe and efficient charging. Modeling and analysis of the proposed system is done in MATLAB/Simulink for steady state and transient characteristics. Simulation results prove that the power factor, voltage stress of semiconductor devices, Total Harmonic Distortion (THD), DC voltage regulation and charging speed are also improved compared to the conventional charger topologies. The proposed onboard charger is a solution with high power density, low cost and energy efficiency for next generation applications to electric vehicle charging.