Dependable, efficient, scalable architecture for management of large-scale batteries

Abstract — Conventional battery management systems (BMSs) for electric vehicles (EVs) are designed in an ad hoc way, causing the supply of EVs to fall behind the market demand. A well-designed, combined hardware-software architecture is essential for the management of a large-scale battery pack that consists of thousands of battery cells as in Tesla Motors and Chevy Volt. We propose a dePendable, effIcient, Scalable Architecture (PISA) that effectively monitors a large number of battery cells, efficiently controls and reconfigures, if needed, their connection arrangement. PISA is monarchy-based and supports hierarchical, autonomous management of battery cells, where a global BMS orchestrates a group of local BMSs. A local controller on each local BMS autonomously manages an array of battery cells, and the global controller reconfigures the connectivity of such battery-cell arrays in coordination with the local controllers. Configuration of a battery system is controlled by three types of switch—called P-, S-, and B-switches—and an algorithm that configures these switches. Our evaluation results show that PISA effectively tolerates battery-cell failures 10 times— while achieving service cost savings 7.4 times—more than a conventional BMS. This superior performance not only extends the battery life significantly, but also provides the flexibility in supporting diverse electric power demands from a growing number of on-board applications. I