基于三次样条插值法的储能锂电池建模与参数辨识

Modeling and Parameters Identification of Li-ion Battery for Energy Storage Based on Cubic Spline Interpolation Method

针对锂电池低荷电状态时输出变化大和模型参数辨识困难问题,提出一种基于三次样条插值法的建模与参数辨识方法。首先建立了含SOC动态的三阶3RC-3D等效电路模型,分析了低SOC时应用最小二乘法对不同模型参数进行辨识产生的误差。在此基础上,结合三次样条插值法的拟合特性和合适的边界条件,构造了三次样条插值函数,在SOC≤10%区间进行了模型各参数辨识,并拟合出了模型参数变化曲线。最后,将辨识后的模型参数曲线与混合脉冲功率特性HPPC(Hybrid Pulse Power Characterization)试验的实际测量值进行了对比。从比较结果看,本文所提的辨识方法减小了参数辨识误差,提高了模型精度,验证了在SOC≤10%区间应用三次样条插值法进行锂电池模型参数辨识的有效性。仿真结果表明,基于三次样条插值辨识方法建立的三阶3RC-3D等效电路模型能够高精度地跟踪锂电池输出外特性。

A method of modeling and parameters identification based on the cubic spline interpolation method is proposed to solve the problems of large output variation and difficulty in the model parameters identification of Li-ion batteries in a low state-of-charge(SOC).First,a third-order RC-D equivalent circuit model with SOC dynamics is established,and the errors that are caused by using the least squares method for the identification of different model parameters in a low SOC are analyzed.On this basis,combined with the fitting characteristics of the cubic spline interpolation method and appropriate boundary conditions,a cubic spline interpolation function is constructed.The model parameters are identified in the range of SOC≤10%,and the curve of model parameters is fitted.Finally,the curves of identified model parameters are compared with the actual measured values in the Hybrid Pulse Power Characterization(HPPC)test.According to the comparison results,it is found that the proposed identification method reduces the parameter identification error and improves the model accuracy.The validity of the cubic spline interpolation method for model parameters identification of Li-ion batteries in the range of SOC≤10%is verified.Simulation results show that the output characteristics of Li-ion batteries can be accurately tracked by the established third-order 3RC-3D equivalent circuit model based on the cubic spline interpolation method.