Lithium-Ion Battery Charge Equalization Algorithm for Electric Vehicle Applications

• Published in: IEEE transactions on industry applications Vol. 53; no. 3; pp. 2541 - 2549
• Main Authors: Hannan, Mohammad Abdul, Hoque, Md. Murshadul, Peng, Seow Eng, Uddin, M. Nasir
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.05.2017; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Charge equalization algorithm; charging and discharging lithium-ion battery; Control systems; DC-DC power converters; electric vehicle (EV); Electric vehicles; Integrated circuits; Lithium; Lithium ions; lithium-ion battery; Monitoring; monitoring integrated circuit (IC); Power loss
• ISSN: 0093-9994; 1939-9367
• DOI: 10.1109/TIA.2017.2672674

The lithium-ion batteries are commonly used in electric vehicle (EV) applications due to their better performances as compared with other batteries. However, lithium-ion battery has some drawbacks such as the overcharged cell which 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. This paper presents a battery charge equalization algorithm for lithium-ion battery in EV applications to enhance the battery's performance, life cycle, and safety. The algorithm is implemented in series-connected battery cells of 15.5 Ah and 3.7 V nominal each using a battery monitoring integrated circuit for monitoring and equalization of an 8-cell battery pack using a bidirectional flyback dc-dc converter as the channel for charging and discharging of the battery cell. The obtained results show that the developed charge equalization controller algorithm performs well in equalizing both undercharged and overcharged cells, and equalizes the cell within the safety operation range of 3.81 V. To validate the charge equalizer performance, the proposed algorithm outperforms with other studies in terms of balancing, equalization speed, low power loss, and efficiency. Thus, the proposed battery charge equalization algorithm proves an effective and automated system to modularize the battery charge that improves the safety and life cycle of battery.