动力电池组汇流排过载能力及电流均衡性影响因素研究

Research on Overloading Capacity of Bus Bars in Battery Module and Influence Factors of Current Balance

以某电动汽车动力电池组软包电池单体汇流连接排为研究对象,对不同结构、不同厚度的汇流排进行热电耦合数值计算,探讨了汇流排结构形状、汇流排电流I/O方式、汇流排焊缝宽度、焊缝位置对汇流排温升和电池单体均衡性的影响。以标准汇流排为研究对象,在两进两出电流不同分配方式下,重点分析汇流排对电流均衡性的影响。加工了铝质汇流排,采用多路温度测试仪对铝质汇流排进行实验测试,在不同电流作用下,实验温升和数值模拟温升之间的误差在5%之内。研究结果表明,钣金折弯对汇流排的过载能力影响不大,在汇流排表面开孔会显著降低汇流排的过载能力;在一定范围内增大汇流排厚度可以显著提升汇流排的过载能力;汇流排的焊缝宽度和焊缝位置对过载能力有一定影响,其中焊缝位置影响更大一些。最后对汇流排温升过高以及电流分配不均衡的机理进行了详细分析。

The bus bar connection of power battery pack of a electric-driven vehicle was studied, and the thermo-electric coupling effects were numerically calculated based on bus bars with different structures and thicknesses. The influences of bus bars structure, current I/O mode,welding width, location on the temperature rise of the bus bars and the balance of the cell were researched. Especial-ly ,taking the standard bus bar as the research object？ the influences of the bus bar on the current bal-ance was analyzed under the 2-in and 2-out current distribution mode. The standard aluminum bus bar was developed,and temperature rising of aluminum bus bar was inspected under various currents by using temperature tester, the errors between the experimentally measured rising temperature and the numerical simulation results are within 5%. The analysis results show that metal sheet bending has little effects on the overloading capacity of bus bars. However,the overloading capacity was signifi-cantly reduced with opening structures in the bus bar. Increasing of the bus bars thickness to some ex-tent may significantly improve the overloading capacity. The width and location of the bus bar welding have some impacts on the capacity, and the influences of the welding locations are greater than that of welding widths. Finally, the mechanism of the bus bar temperature rising and the current unbalanced distribution was analyzed.