Research On Internal Short Circuit Detection And Graded Warning System Of Lithium Battert

In recent years,with the rapid development of the new energy industry,lithium-ion batteries are widely used in electric vehicles,energy storage stations and other new energy fields with their advantages of high energy storage density and light weight.However,lithium-ion batteries often experience fire and explosion under improper conditions such as collision,compression,over charging,and over discharging.Before the ignition and combustion,internal short circuit(ISC)usually occurs in lithium-ion batteries.In order to improve the safety of lithium-ion batteries,it is critical to study the detection methods of ISC in lithium-ion batteries and design a graded warning system for ISC in lithium-ion battery packs.The main work of this article is as follows:(1)A method for identifying ISC in lithium batteries based on voltage and temperature has been proposed.Taking a battery pack composed of six batteries in series as an example,first,a model analysis is conducted on the series battery pack to obtain the difference in voltage and temperature between a normal battery and an ISC battery.The basis for distinguishing ISC based on voltage and temperature is obtained.By combining the Local Outlier Factor(LOF)algorithm and hypothesis testing method,the detection of ISC batteries in series battery packs is achieved.(2)A method for estimating the equivalent resistance of ISC and establishing risk levels has been proposed.In order to quantify the risk level of ISC batteries,based on the electric thermal coupling model of lithium batteries,Recursive Least Squares(RLS)is used to estimate the state of charge(SOC)of ISC batteries.Then,the estimated equivalent resistance value of ISC is estimated based on the SOC and temperature change rate,and the ISC risk level is established based on the estimated equivalent resistance value of ISC.(3)A lithium battery pack internal short circuit graded warning system was implemented using the proposed method.The system includes modules such as data acquisition,parameter calculation,ISC detection,and risk level establishment.The user interface is designed using Matlab’s App designer tool.The system obtains real-time voltage,current,and temperature data of each battery in the simulation software for the lithium battery pack,and uses the data to identify ISC and estimate resistance values for the lithium battery pack.The battery pack information is displayed on the user interface,and a warning is issued when an ISC occurs,achieving a graded warning for ISC in the lithium battery pack.The simulation results show that the proposed method has high confidence level and accuracy,and the designed system can realize effective early warning of short circuit in battery pack.