A lithium battery pack balance control method and system for dynamically correcting SOC

Abstract

The invention provides a lithium-battery-pack equalization control method and system based on a dynamic correction SOC. The method includes the following steps that the SOC of each lithium battery ina lithium battery set is obtained; the range rsoc of the battery set is calculated; the range rsoc and the preset range threshold are compared; the mean value (the symbol can be seen from the description) of the SOCs of all the lithium batteries are selected to serve as a balanced target SOC, charge equalization is conducted on the lithium batteries with the SOC lower than the value (the symbol can be seen from the description), and discharging equalization is conducted on the lithium batteries with the SOC higher than the value (the symbol can be seen from the description), wherein dSOC refers to an equalization control band. The method and the system have the advantages that the modularity is high, the balancing speed is high, the use efficiency of the batteries is improved and the service life of the batteries is prolonged.

Description

technical field [0001] The invention belongs to the field of new energy vehicle batteries, and in particular relates to a lithium battery pack balance control method and system for dynamically correcting SOC. Background technique [0002] Affected by environmental pollution issues and policies and regulations, new energy vehicles represented by hybrid and pure electric vehicles have received more and more attention. Due to its high energy density, low self-discharge rate, long life and no pollution, lithium batteries have gradually replaced lead-acid batteries as the main power battery energy in the field of electric vehicles. [0003] When using lithium batteries in electric vehicles, in order to meet the requirements for load capacity and battery life, lithium battery packs must meet certain capacity and voltage requirements. For this reason, single lithium batteries are often connected in parallel to form battery cells to solve the problem of insufficient capacity of a s...

AI Technical Summary

Problems solved by technology

[0007] (1) The equalization time is long, which is a common problem in the existing equalization systems. The equalization time of most equalization systems is more than one hour, and some even reach several hours.

[0008] (2) The balance based on external voltage has been extensively studied in the existing commonly used equalization technology, but due to the difference in the capacity of the single battery, the external characteristics of the charging and discharging voltage of each single battery are inconsistent, especially in the single battery In the later stage of charging, the voltage of the single battery rises rapidly, so that the use of the external voltage of the battery as the criterion of the consistency of the battery pack has the problem of unstable balance criterion.

At the same time, the study also found that this method has no obvious effect on increasing the available capacity of the battery pack before and after equalization.

[0009] (3) The practicability needs to be improved, the circuit design is relatively complex and the integration is not enough, and it is not possible to conveniently carry out modular expansion with the increase in the number of battery cells in series in the battery pack, etc.

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