A Parameter Identification Method of Battery Equivalent Circuit Model based on Impedance Spectrum

With the increasing application of lithium ion batteries, the importance of research including battery state of charge, life estimation and other aspects is also increasing. At present, these directions are mainly based on battery models. Battery models are mainly divided into two types: mechanism model and equivalent circuit model. The equivalent model has been applied more widely because of its simple structure, small number of parameters and small amount of calculation. In this context, a method of identifying parameters of equivalent circuit model based on battery impedance spectrum is proposed. Firstly, the equivalent circuit impedance expression is obtained through the model structure, and the characteristic points can be selected to calculate the parameters in the formula. Based on the measured impedance spectrum, the initial values of the model parameters were calculated by using the characteristic points, and then the initial values were substituted into the Levenberg-Marquardt algorithm to get the final solution. The method combines the impedance profile features with iterative optimization algorithm, which has the advantages of high identification accuracy and fixed identification results