Structural Analysis for Fault Diagnosis and Sensor Placement in Battery Packs

Energy storage systems for transportation and grid applications, and in the future for aeronautical applications, require the ability of providing accurate diagnosis to insure system availability and reliability. In such applications, battery packs may consist of hundreds or thousands of interconnected cells,and of the associated electrical/electronic hardware. This paper presents a systematic methodology for approaching some aspects of the design of battery packs, and in particular the development of diagnostic strategies, using cell models and structural diagnosis methods. First, the analytical redundancy that is intrinsic in the battery system is determined. Then, graph-theoretic tools are used to construct general structural models of two common battery pack topologies, and illustrate how the redundancy present in different measurements (current, voltage, and temperature) can be used to improve monitoring and diagnosis of a battery system. Possible sensor placement strategies that would enable the diagnosis of individual sensor faults and individual cell faults for different battery topologies are analyzed as well.While the work presented in this paper is only one step in the design of a large battery pack design, it is an important and needed advancement.