An estimation method of lithium battery soc and sop based on second-order rc model

Abstract

The present invention proposes a lithium battery SOC and SOP estimation method based on a second-order RC model. The estimation method includes the following steps: step S1, selecting the type and model of the lithium battery, obtaining corresponding technical parameters and establishing a battery equivalent circuit Model; step S2, at a specific temperature, conduct HPPC experiments on the battery and obtain battery characteristic parameters, establish the relationship between battery open circuit voltage and SOC, combine the optimization method for parameter identification, and feed back the obtained parameters to the model; step S3, Combined with the EKF algorithm, the SOC closed-loop estimation is performed; step S4, the instantaneous power and the limited power of the battery are estimated according to P=U*I. The innovation of the invention lies in that the original battery model with current as input and voltage as output is improved to a model with voltage as input and current as output. Because for SOP estimation, the model of calculating current with known voltage is more suitable, which can solve the problems of cumbersome steps and large amount of calculation in the existing methods.

Description

technical field [0001] The invention relates to the technical field of lithium-ion battery state-of-charge and power state prediction, in particular to a lithium-ion battery SOC and SOP estimation method based on a second-order RC model. Background technique [0002] Although lithium-ion battery technology continues to improve, it still cannot fully meet the needs of use in terms of life and safety. SOC reflects the amount of remaining power in the battery. In the power battery management system, SOC plays an important role and is also the basis for other state estimation. SOP is the ability of the battery to output power. The accuracy of SOC and SOP prediction directly affects battery performance. performance, longevity and safety of use. [0003] At present, there are many methods for SOC estimation. The commonly used estimation methods can be divided into the following categories: ampere-hour integration method, open circuit voltage method, estimation method based on equ...

AI Technical Summary

Problems solved by technology

[0003] At present, there are many methods for SOC estimation, and the commonly used estimation methods can be divided into the following categories: ampere-hour integral method, open circuit voltage method, estimation method based on equivalent circuit model, estimation method based on electrochemical model, and estimation method based on machine learning model. Estimation methods, among which the ampere-hour integration method is greatly affected by the initial SOC and current measurement errors, and the accuracy is poor; the open circuit voltage method is not suitable for dynamic estimation; the method model of the electrochemical model is too complicated and the calculation is large; the machine learning method requires a large amount of data training , the estimation accuracy outside the training range is not high; the closed-loop estimation algorithm based on the equivalent circuit model has reliable accuracy, but it is more dependent on the accuracy model, which is the most used method for battery SOC estimation

[0004] In recent years, there are mainly two kinds of SOP estimation methods commonly used: Map-based estimation method and model-based dynamic estimation method. Among them, the Map-based estimation method is simple and reliable, but requires a large number of offline calibration tests, and is only suitable for fully rested battery

Images