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 comprises the following steps: measuring external magnetic field distribution of a lithium battery pack at equal discharge capacity intervals in a constant-current discharge process of the lithium battery pack to be measured; calculating the relative change of the external magnetic field distribution of the lithium battery pack in the equal capacity interval; adopting a statistical analysis method to extract statistical feature vectors relative to magnetic field changes; and analyzing the statistical feature vectors by adopting a statistical learning method, and detecting and evaluating the consistency of the battery pack and positioning the batteries with abnormal performance according to an analysis result. The device comprises a motion scanning device, a magnetic field acquisition device, a control device, a battery test device and a sample device. The method has the advantages of no damage, no contact, high efficiency and the like, solves the problem that an existing lithium battery pack consistency detection method cannot monitor all single batteries in the battery pack in a service state on line, and provides technical support for scenes of life prediction, maintenance, safety evaluation and the like of the lithium battery pack.

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 batteries are currently commonly used secondary batteries. They have the advantages of high energy density, large output power, no memory effect, and fast charging and discharging speeds. They are widely used in consumer electronics, electric vehicles, grid energy storage, aerospace and other fields. . The output voltage and capacity of single lithium batteries are limited. In order to meet the needs of different application scenarios, it is necessary to increase the output power of single lithium batteries 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, inte...

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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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