并联锂离子电池组的模型化与电流分配

Modelling and Current Distribution of Parallel-connected Lithium Cells

摘要:

近些年发表了大量关于消除串联电池组能量不均衡方法的文献;然而,关于电池性能的变化对并联电池组的影响的研究还比较少;为探索具有不同特性的电池进行并联联接时的影响,基于锂电池的戴维宁等效电路模型建立了并联电池组的数学模型;在此基础上,通过内阻差ΔR和容量差ΔQ两种参数情况分析了并联电池组内电流分配的基本机制;为进行对比分析,选择了4个不同老化程度的锂电池以构建不同的电池组;采用非线性最小二乘法对模型的未知参数进行辨识,并利用MATLAB进行建模仿真比较;仿真实验结果表明,对于有不同老化程度电池的并联电池组,并联电池组内的电流会发生很大的变化,这可能导致更严重的不一致性问题并进一步加速电池老化。

Abstract:

Methods of removing the energy imbalance of cells connected in series have been extensively reported within literature for the past years. However, there has been little discussion around the effect that the variation of the battery performance has when cells are connected electrically in parallel. In order to explore the impact of connecting cells, with varied properties, in parallel,the model of parallel battery pack is established based on the venin equivalent circuit model of lithium ion cell.On this basis, the basic mechanism of the current distribution in the parallel battery pack is analyzed by two parameter scenarios, resistance variation ΔR and capacity variation ΔQ. For comparative analysis, four different aging lithium ion cells are selected to build different battery packs. A nonlinear least squares algorithm was used to estimate the vector of unknown model parameters, and modeling and simulating in MATLAB. The simulation indicate that, with different degraded cells in parallel, there could be large difference in current, which may cause further accelerated degradation and a more serious inconsistency problem.