The trend toward more electric vehicles has created a need for high voltage, high efficiency, and long life energy storage systems. The objective of this project is to use our expertise and testing capabilities to develop a complete integrated battery system solution for electric, hybrid electric, and plug-in hybrid electric vehicles. This modular design solution will be able to work with battery systems with different chemical composition, capacity, and voltage. Several projects in Dr. Emadi’s Power Electronics and Motor Drives Lab are being used to test the proposed solutions, e.g., Hummer hybrid electric conversion kit (HECK) project, auto rickshaw project, and Formula Hybrid racecars. The battery system solutions cover battery protection, energy management, and cell balancing.

Battery protection is important to protect the battery system from undesirable conditions including over voltage, under voltage, over current, over temperature, and under temperature. Electronic control/management unit is the intelligent system, which is used to collect the information of the battery and to communicate with the main electronic control unit of the vehicle. Balancing is of critical importance concerning the life of the battery system because, without the balancing system, the individual cell voltages will drift apart over time. The capacity of the total pack will decrease more quickly during operation, which will result in the failure of the battery system. This condition is especially severe when the battery has a long string of cells (high voltage battery systems) and frequent regenerative braking (charging) is done.

Jian Cao received his B.S. degree (’04) in automation from Beijing University of Technology in China and his M.S. degree (’07) in electrical engineering from Illinois Institute of Technology (IIT) in Chicago. He is now a Ph.D. student in the Electrical and Computer Engineering Department at IIT. His master’s thesis titled “Efficiency and loss models for key electronic components of hybrid electric vehicles’ electrical propulsion systems” was sponsored by the National Renewable Energy Laboratory (NREL). His current research concentrates on propulsion battery systems and long string battery solutions for electric, hybrid electric, and plug-in hybrid electric vehicles. Specifically, this research includes balancing, protection, and management of energy storage systems. His field of interests also includes drive train design and control strategy development for hybrid electric vehicles.