A lithium battery pack consistency detection method and device based on in-situ magnetic field imaging

Abstract

The invention discloses a lithium battery pack consistency detection method and device based on in-situ magnetic field imaging. The method includes: during the constant current discharge process of the lithium battery pack to be tested, measuring the external magnetic field distribution of the lithium battery pack at equal discharge capacity intervals; calculating the relative change of the external magnetic field distribution of the lithium battery pack within the equal capacity interval; using a statistical analysis method to extract Statistical eigenvectors of relative magnetic field changes; Statistical learning methods are used to analyze the aforementioned statistical eigenvectors, and based on the analysis results, battery pack consistency detection and evaluation and abnormal performance battery location are realized. The device includes motion scanning equipment, magnetic field acquisition equipment, control equipment, battery testing equipment and sample equipment. The method has the advantages of non-destructive, non-contact, high efficiency, etc., and solves the problem of online monitoring of all single cells in the battery pack under the service state of the existing lithium battery pack consistency detection method. Security assessment and other scenarios provide technical support.

Description

technical field [0001] The invention relates to the field of battery detection, in particular to a lithium battery pack consistency detection method and device based on in-situ magnetic field imaging. Background technique [0002] Lithium-ion battery is a commonly used secondary battery. It has the advantages of high energy density, high output power, no memory effect and fast charging and discharging speed. It is widely used in consumer electronics, electric vehicles, grid energy storage and aerospace. . The output voltage and capacity of a single lithium battery are limited. In order to meet the needs of different application scenarios, it is necessary to increase the output power of the single lithium battery through series connection, and increase the output capacity through parallel connection. However, practice shows that the consistency of single cells in the battery pack will gradually deteriorate during use, including capacity, internal resistance, self-discharge r...

AI Technical Summary

Problems solved by technology

[0003] At present, the main method of online detection of battery pack consistency at home and abroad is to measure the battery terminal voltage and conduct consistency evaluation based on the voltage difference between the batteries. This method is suitable for batteries connected in series, but it will also be affected by the battery measurement accuracy. , The influence of battery polarization effect

However, for a battery module with a large number of batteries connected in parallel, the single cells have the same terminal voltage, and the voltage change caused by an abnormality in a single cell is very small, so it is difficult to detect the faulty battery through the voltage change

In addition, the unbalanced current between the single cells in the battery pack can be used to detect the consistency of the performance of the battery pack, but it is impractical and expensive to add a current sensor for each single cell, so in practical applications This method is rarely used in

[0004] It can be seen that due to the influence of environmental factors and complex working conditions and the limitations of the method itself, the existing battery pack consistency detection method cannot monitor and evaluate the consistency of the battery pack in real time for all single cells in the battery pack. At the same time, it is impossible to accurately locate the position of the abnormal performance single battery in the series-parallel battery pack, which is not conducive to the safe maintenance of the battery pack

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