Design and Analysis of a 3.3 kW Multifunctional Onboard EV Charger with Improved Power Factor

Abstract

This work presents the design and performance assessment of a two-stage onboard charger for electric vehicle (EV) applications. The topology integrates a totem-pole power factor correction (PFC) converter as the front-end stage and a bidirectional buck-boost converter as the back-end stage. The system is designed to function in two operating conditions. In grid-connected mode (GCM), the main battery is charged from a single-phase 230 V AC supply and can return energy to the grid during bidirectional operation. In driving mode (DM), when the vehicle is disconnected from the grid, the same converter configuration is employed to deliver power from the main battery to the 12 V auxiliary bus and other low-voltage loads. This approach avoids the requirement for an additional DC-DC converter by appropriately reconfiguring the existing hardware, thereby reducing system complexity and improving overall power density. The charger is rated at 3.3 kW during grid-connected operation and delivers up to 550 W in driving mode. The totem-pole PFC converter ensures near-unity power factor and low grid-current distortion, with independent control of both stages. The suggested system is validated through simulation in MATLAB/Simulink, and harmonic analysis shows that the input current total harmonic distortion (THD) of 1.15% falls within the acceptable limits defined by IEEE 519 standard.