Design and Analysis of a Novel Multi-Functional Onboard Battery Charger for Electric Vehicles

This paper presents the design and analysis of a dual-stage onboard electric vehicle charger utilizing an interleaved totem pole AC-DC converter at the front end and a synchronous buck-boost DC-DC converter at the back end. The proposed onboard charger supports two operational modes. One is grid-connected mode (GCM), where the main battery inside the EV is charged from a single-phase AC supply. There is also a possibility of feeding power back to the grid from the main battery in the deregulated environment. The second is the driving mode (DM) when disconnected from the grid, where the main battery supplies power to the auxiliary battery and other auxiliary loads rated at 12/24V within the EV without requiring an additional DC-DC converter. This is achieved through the optimal utilization of components in the charger, ensuring maximum power factor and minimal harmonic distortion in the input current during the grid-connected mode, aided by independent control loops. This paper provides a comprehensive operational overview and presents simulation studies of a 10-kW onboard charger in grid-connected mode and a 2-kW charger in driving mode.