Design of an active battery management system for electric vehicles

State of the art battery modules for traction drives contain battery management systems (BMS) with passive balancing units to ensure an equal state of charge (SOC) for all cells after charging. This paper will examine the requirements for employing active balancing units in traction batteries to maximize the use and lifetime of the whole battery pack under real driving conditions. After the power requirements are calculated a comparison between available active balancing methods determines which method is suitable. Finally, simulation results and experimental data from the prototype balancing unit are given.