基于电化学阻抗谱的锂电池模组短路故障诊断方法研究

Research on Short-circuit Fault Diagnosis Method of Lithium Battery Module Based on Electrochemical Impedance Spectroscopy

摘要:

电化学阻抗谱能够反映电池内部关键状态信息，利用电化学阻抗谱可实现对电池的监测及故障诊断，避免发生安全事故。针对电动汽车在充电时发生安全事故的概率最高且大部分是由电池短路所引起的问题，设计了一种能够在电池充放电时提取电池模组与电池单体阻抗信息的充电桩装置，对锂电池模组短路故障诊断方法进行了研究。首先，详述了所设计充电桩的拓扑与控制方法以及电池模组阻抗测量的原理；然后，通过仿真验证了充电桩可以在对电池模组进行充放电的同时提取其阻抗信息，并分析对比了两种扰动信号的优劣、不同程度短路故障下电池单体与电池模组的阻抗变化以及不同支路的电池发生短路时对模组阻抗的影响；最后，得到了短路故障下电池单体与电池模组的阻抗谱都会缩小并向左移动，并且短路电池越集中在同一支路，模组的阻抗变化越明显的结论。

Abstract:

Electrochemical impedance spectroscopy (EIS) can reflect the critical internal state information of batteries, and using EIS can achieve the monitoring and fault diagnosis of batteries to avoid safety accidents. Aiming at the fact that electric vehicles have the highest probability of safety accidents during charging and most of the safety accidents are caused by short circuit of batteries, the short circuit fault diagnosis method of lithium battery module is studied by taking charging pile for example. Firstly, the topology and control method of the designed charging pile,and the principle for impedance measurement of battery module are described in detail. And then, the simulation verifies that the charging pile can charge and discharge the battery module at the same time and extract its impedance information. The advantages and disadvantages of two kinds of disturbance signals, and the impedance changes of battery cells and battery modules under different degrees of short-circuit faults are analyzed and compared as well as the effects of short circuit on module impedance of batteries in different branches. Finally, it is concluded that the impedance spectroscopy of both battery cell and battery module can shrink and shift to the left under a short-circuit fault, and the more the short-circuited cells are concentrated in the same branch, the more obvious the impedance change of module is.