Lithium-Ion Battery Charge Equalization Algorithm for Electric Vehicle Applications

This paper presents a battery charge equalization algorithm for lithium-ion battery in electric vehicle (EV) applications. Presently, EV attracts the people interests to be developed and utilized as it fully uses the electric energy from the battery pack to drive the vehicle motor and operate the accessories due to reduction of carbon and greenhouse gases emissions. The commonly used battery in the market is the lithium-ion battery due to its better performance as compared to other batteries. However, lithium-ion battery has some drawbacks such as the overcharged cell has a risk of explosion, the undercharged cell eventually reduces the life cycle of the battery, and unbalanced charge in series battery gradually reduces overall charge capacity. A battery charge equalization controller is capable to enhance the battery's performance, life cycle and safety. In this paper, a charge equalization algorithm is proposed and implemented using a battery monitoring integrated circuit for monitoring and equalization of an 8-cell battery pack using bidirectional flyback DC-DC converter as the channel for charging and discharging of the battery cell. The proposed equalization method proves an effective and automated system to modularize the battery charge that improves the safety and life cycle of battery.