Construction method of SOC (state of charge)-OCV (open-circuit voltage) model of lithium ion battery

Abstract

The invention discloses a construction method of an SOC (state of charge)-OCV (open-circuit voltage) model of a lithium ion battery, which is used for improving the estimation accuracy capability of SOC of the lithium ion battery. The method mainly comprises steps as follows: 1) at the normal temperature, SOC and OCV data of the battery are actually measured; 2) the SOC is divided into three sections which are partially overlapped; 3) the three sections are subjected to low-order polynomial fitting; 4) the overlapped part is subjected to linear interpolation processing; 5) a fitting formula iscorrected with consideration of SOH change; 6) the fitting formula is corrected with consideration of temperature change; 7) the fitting formula is finally corrected with comprehensive considerationof SOH and temperature change; and 8) the SOC-OCV relation model is constructed. The method has the advantages as follows: the calculated quantity is small while the overall accuracy is high; a fitting model considers the influence of health degree of the battery on the model; the model complexity degree is not increased in a fitting result; the method has better universality and is not just limited to a certain battery; and the method has better adaptability and is suitable for conditions of environment change and battery feature decline after long-time application of the battery.

Description

technical field [0001] The invention relates to the application field of new energy automobile batteries, in particular to establishing a reasonable relational model between the SOC and the open circuit voltage (OCV) of the lithium ion battery before being used for estimating the state of charge (SOC) of the lithium ion battery. Background technique [0002] The SOC of the battery reflects the remaining power of the battery, and is a very basic and important monitoring indicator in the battery management system. Since the relationship between battery SOC and other parameters of the battery is highly nonlinear, the SOC has to be obtained through intermediate physical quantities; coupled with the randomness of changes in external and internal environmental parameters, the estimation method based on the mathematical model of the system is not accurate enough. Therefore, the anti-interference ability and adaptive ability of battery state of charge estimation must be suppressed a...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a method for establishing a state of charge and open circuit voltage model of a lithium-ion battery, which solves the problems of complex SOC-OCV models, large calculations, low estimation accuracy and difficult implementation in the traditional lithium-ion battery SOC estimation algorithm

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