Model Based Design of Balancing Systems for Electric Vehicle Battery Packs

Battery packs containing multiple cells in series require a balancing system in order to ensure energy and power requirements for the battery pack are maintained throughout its life. Based on the equivalent circuit model (ECM) of a cell, a new framework is proposed which can accommodate a control-oriented model of a balancing system while maintaining the same measured input and output as an ECM. This allows for model-based design of the balancing control system and other battery management system functions such as state estimation. Three examples of balancing system models are presented to show how balancing systems can be designed and analyzed. A model-based controller is then designed for one balancing system to show how the framework can be used to generate less heat while removing imbalance at the same rate.