Lithium ion battery module SOC difference calculation method and device

Abstract

The invention discloses a lithium ion battery module SOC difference calculation method and device. The method is realized through a computer and comprises the following steps: obtaining the monitoring data of two modules during the charging of a lithium iron phosphate system battery pack, the data including the voltage and the SOC value; intercepting the charging data from 40% SOC to 80% SOC; fitting the intercepted data of the two modules through a sigmoid function respectively; calculating SOC values corresponding to inflection points of the charging SOC voltage curves of the two modules according to the fitting parameters; and calculating the SOC difference value corresponding to the two inflection points, wherein the SOC difference value is the SOC difference of the two modules. Aiming at an existing method for calculating the SOC difference of the lithium ion battery module of the lithium iron phosphate system, the invention provides the method for calculating the SOC difference of the module according to the charging data, so that the reliable and rapid calculation of the SOC difference between modules in the battery pack can be realized when the charging is finished; and the method can be applied to module consistency detection in a BMS or remote analysis and calculation in monitoring of a power battery remote monitoring big data analysis platform.

Description

technical field [0001] The invention relates to the technical field of power battery packs for vehicles, in particular to a method and equipment for calculating the SOC difference of a lithium-ion battery module. Background technique [0002] With the popularization of electric vehicles, the battery safety of electric vehicles has received more and more attention. The power battery used in electric vehicles generally uses a large number of single cells to be combined in series and parallel to meet capacity and voltage requirements. Due to the inconsistency in the production of single cells and the inconsistency of use conditions when the battery is running, some single cells or parallel modules have faults such as undervoltage / low capacity / large self-discharge during operation, and these faults make the single cell The SOC of the single cell or module is lower than that of other single cells or modules during operation, so that the battery pack cannot perform its due perfor...

AI Technical Summary

Problems solved by technology

Due to the inconsistency in the production of single cells and the inconsistency of use conditions when the battery is running, some single cells or parallel modules have faults such as undervoltage / low capacity / large self-discharge during operation, and these faults make the single cell The SOC of the single cell or module is lower than that of other single cells or modules during operation, so that the battery pack cannot perform its due performance and affect the normal use of the battery pack, and due to the voltage characteristics of lithium iron phosphate, the voltage difference caused by the difference in SOC is very large. Small, it is difficult to calculate the SOC difference between modules with traditional methods

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