Equalization method taking SOC difference between batteries as index

Abstract

The invention discloses an equalization method taking the SOC difference between batteries as an index, and belongs to the field of battery energy storage. The method comprises the following steps: building a conversion table of voltage and SOC under different battery pack SOCs in different intervals according to the OCV-SOC curve of the battery pack in different temperature intervals; measuring the voltage of each parallel battery pack in the battery packs, finding out the battery packs with the highest and lowest voltage, and calculating the voltage difference; looking up a table according to the battery pack temperature and the battery pack SOC to obtain a conversion value of the voltage and the SOC, and estimating the SOC range delta SOC according to the value and the voltage range of the parallel battery pack; and when the delta SOC is greater than a preset equalization threshold value, enabling the BMS to start equalization until the SOC change difference of the two parallel battery packs is greater than the delta SOC. The method is simple to implement, and can better provide an accurate parameter equalization method for the BMS.

Description

technical field [0001] The invention belongs to the field of battery energy storage, and more specifically relates to an equalization method using the SOC difference between batteries as an index. Background technique [0002] Battery balancing is a very important function in the battery management system (Battery Management System, BMS). There are many indicators to judge whether the battery pack is balanced, but the indicator commonly used at present is the battery terminal voltage, because the battery terminal voltage can be more accurate It can accurately reflect the state of charge (State of Charge, SOC) of the battery, and the terminal voltage of the battery can be easily measured directly, but it is often necessary to calculate the terminal voltage difference between the two batteries to determine whether the battery needs to be balanced and whether the balance is completed. This voltage difference is not only related to the SOC difference between batteries, but also ...

AI Technical Summary

Problems solved by technology

[0002] Battery balancing is a very important function in the battery management system (Battery Management System, BMS). There are many indicators to judge whether the battery pack is balanced, but the indicator commonly used at present is the battery terminal voltage, because the battery terminal voltage can be more accurate It can accurately reflect the state of charge (State of Charge, SOC) of the battery, and the terminal voltage of the battery can be easily measured directly, but it is often necessary to calculate the terminal voltage difference between the two batteries to determine whether the battery needs to be balanced and whether the balance is completed. This voltage difference is not only related to the SOC difference between batteries, but also largely affected by factors such as battery working status, battery charge and discharge current, etc., which makes it often difficult to provide more accurate equalization parameters for BMS

Although using battery SOC as a balance indicator can provide accurate balance parameters for BMS, it is extremely complicated to accurately estimate the SOC of all batteries in the battery pack

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