Wang Lizhi, Sun Yusheng, Wang Xiaohong, Wang Zhuo, Zhao Xuejiao
Institute of Unmanned System, Beihang University, Beijing 100191, China.
Key Laboratory of Advanced Technology of Intelligent Unmanned Flight System of Ministry of Industry and Information Technology, Beijing 100191, China.
Materials (Basel). 2019 Mar 30;12(7):1054. doi: 10.3390/ma12071054.
Lithium-ion batteries are widely used as basic power supplies and storage units for large-scale electric drive products such as electric vehicles. Their reliability is directly related to the life and safe operation of the electric drive products. In fact, the cells have a dependent relationship with the degradation process and they affect the degradation rate of the entire battery pack, thereby affecting its reliability. At present, most research focuses on the reliability of battery packs and assumes that their cells are independent of each other, which may cause the reliability of the evaluation to deviate greatly from the actual level. In order to accurately assess the reliability of lithium-ion batteries, it is necessary to build a reliability model considering the dependency among cells for the overall degradation of lithium-ion battery packs. Therefore, in this study, based on a lithium-ion battery degradation test, the Wiener process is used to analyze the reliability of four basic configurations of lithium-ion battery packs. According to the degradation data of the battery packs, the Copula function is used to quantitatively describe the dependent relationship in the degradation process of a single battery, and the quantitative dependent relationship is combined with the reliability model to form a new reliability model. Finally, taking the battery system of Tesla S as an example, a feasible optimization method for battery pack design is provided based on the model constructed in this work.
锂离子电池被广泛用作电动汽车等大型电力驱动产品的基本电源和存储单元。它们的可靠性直接关系到电力驱动产品的寿命和安全运行。实际上，电池单元与退化过程存在依赖关系，并且它们会影响整个电池组的退化速率，从而影响其可靠性。目前，大多数研究集中在电池组的可靠性上，并假设其电池单元相互独立，这可能导致评估的可靠性与实际水平有很大偏差。为了准确评估锂离子电池的可靠性，有必要建立一个考虑电池单元之间依赖关系的可靠性模型，用于锂离子电池组的整体退化。因此，在本研究中，基于锂离子电池退化测试，使用维纳过程来分析锂离子电池组四种基本配置的可靠性。根据电池组的退化数据，使用Copula函数定量描述单个电池退化过程中的依赖关系，并将定量依赖关系与可靠性模型相结合，形成一个新的可靠性模型。最后，以特斯拉S的电池系统为例，基于本工作构建的模型提供了一种可行的电池组设计优化方法。
