Electric Vehicles Charging Concepts for Lithium Based Batteries

This paper presents the concept of charging of Lithium Iron Phosphate (LFP) battery cells in an Electric vehicle (EV). Charger topologies play an important role in EVs to increase the performance of the batteries. The batteries should be charged and discharged to achieve the best performance and long lifetime. In this paper, the design of a charger with four battery packs, that consist of eight cells in a series is investigated. Two battery chargers are performed in order to feed the whole battery packs. A current driver is proposed to limit the current from the charger and the operational principle is based on a MOSFET constant current driver. The battery should only be connected when the car needs to drive in order to avoid unnecessary losses. Also a resistor is needed to avoid high starting currents, thus the startup system is required and designed to overcome this problem. The operational principle of the proposed circuit is explained in details and the experimental result are performed to verify the feasibility of the proposed system.