Spatiotemporal Entropy for Abnormality Detection and Localization of Li-ion Battery Packs

Li-ion battery (LIB) packs have been widely used in the vehicle industry. The abnormality detection and localization of battery systems are receiving more and more attention. In this paper, the spatiotemporal entropy is proposed to detect and locate thermal abnormalities of LIB packs. Based on the Karhunen-Loève (KL) decomposition, the spatial entropy and temporal entropy can be constructed from different scales, and then appropriately integrated into the comprehensive spatiotemporal entropy. The kernel density estimation is employed to derive the detection threshold of the spatiotemporal entropy, based on which the abnormality detection can be achieved. The entropy contribution function is designed for abnormality localization based on the spatial basis function (SBF) variations in different modes. The physical meaning of the spatiotemporal entropy is explained from the perspective of the system disorder degree, energy concentration, and information theory. Experiments on the Li-ion battery pack under different fault conditions demonstrate that the proposed method can timely detect and precisely locate the abnormal cells at the early stage.