锂离子电池组聚类筛选低温混合预热系统建模与热分析

Clustering, Modelling and Thermal Analysis of a Hybrid Preheating System-based Lithium-ion Battery Module Under Subzero Environment

摘要:

低温导致锂离子动力电池性能衰减加速、寿命缩减、形成锂枝晶，甚至造成内短路等严重问题，因此预热已经成为电动汽车在低温地区应用的关键问题。此外，电池单体间一致性对电池组整体性能及老化有重大影响。采用聚类分析对锂离子电池单体进行筛选成组，并提出一种附有PTC加热膜和液冷板的混合电池热管理系统，通过计算流体力学建模和数值计算对此系统在-40 ℃环境下的预热效率进行分析。结果表明：对初始方案进行优化后，经过695 s预热电池组最低温度可加热至0℃以上；此外，与纯PTC加热方法相比，电池组温度标准差可降低5.9℃。因此，此系统可在无过多功耗增长的前提下，短时间内高效地将电池组加热至工作状态，预热速度为3.56 ℃/min，且能提升温度均匀性。

Abstract:

Subzero environment results in the accelerated performance degradation， lifespan shortage， lithium planting， and even some severe problems such as internal short circuit of lithium-ion battery cells. Therefore， preheating has become a critical issue for electric vehicle application in the low-temperature area. The consistency between the battery cells has a significant impact on the module performance and aging mechanism. In this paper， the clustering approach was utilized for battery cell selection. In addition， a hybrid battery thermal management system （BTMS） coupled with positive temperature coefficient （PTC） heating film and cooling plate is proposed， the heating efficiency of the proposed system at the ambient temperature （－40℃）was investigated through computational fluid dynamics （CFD） modelling and numerical calculation. The results indicate that the minimum temperature of the battery module can be heated to a state higher than 0 ℃ after 695 seconds of preheating. Besides， the temperature standard deviation of the battery module gets decreased by 5.9 ℃ compared with the pure PTC heating approach. Therefore， this proposed method efficiently heat the battery module to an operational state within a short heating interval， without much energy cost. The preheating speed reaches 3.56 ℃/min. Moreover， the thermal uniformity gets enhanced.