A Bidirectional Cell Balancing System with WPT for EV Lithium-Ion Battery Packs

To ensure the usability and safety of the Electric Vehicles, maintaining the balancing of the Lithium-ion cells in battery packs is essential. In this paper, a bidirectional active balancing solution based on Wireless Power Transfer is proposed. It provides a solution to transit power bidirectionally between the vehicle 12V bus and the high voltage bus to add or remove charges to any cell in the energy storage system. Compared with the regular active balancing method, the proposed system will have reduced size and weight, as well as improved safety provided by contactless balancing. It can also act as a charger for the 12V lead acid battery, which reduces the BOM cost of the vehicle.