An Estimation Method of State of Charge Based on Hysteresis Characteristics of Open Circuit Voltage

Abstract

The invention relates to a charge state estimation method based on open-circuit voltage hysteretic characteristics. The method is used for estimating the charge state of a lithium ion battery online. The method comprises the following steps that 1, a hysteretic characteristic curve of open-circuit voltage and the charge state of the lithium ion battery is obtained offline; 2, initial parameters of an open-circuit voltage hysteretic characteristic self-adaptive model based on a Preisach operator is determined through training according to the hysteretic characteristic curve, and the open-circuit voltage hysteretic characteristic self-adaptive model based on the Preisach operator is established; 3, the charge state of the lithium ion battery is estimated online according to the open-circuit voltage hysteretic characteristic self-adaptive model based on the Preisach operator, and the charge state of the lithium ion battery at the present moment is obtained. Compared with the prior art, the charge state estimation method based on the open-circuit voltage hysteretic characteristics has the advantages of being accurate in modeling, capable of improving the accuracy, accurate in estimation and the like.

Description

technical field [0001] The invention relates to a method for estimating the state of charge, in particular to a method for estimating the state of charge based on the hysteresis characteristic of the open circuit voltage. Background technique [0002] As a key component, the power battery system has been used more and more in the fields of electric vehicles and electric energy storage. In the application process, a battery management system (Battery Management System, BMS) is required to monitor the battery status to prevent overcharging and overdischarging to prolong the battery life. Among them, the accurate estimation of SOC (state of charge) is particularly critical. Most of the SOC estimation methods are obtained by utilizing the corresponding relationship between the SOC and the open circuit voltage (OCV, open circuit voltage), such as the open circuit voltage method, the SOC estimation method based on the model, and the like. The description of the corresponding rel...

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Problems solved by technology

[0003] More simplifications are introduced in the traditional modeling method of the hysteresis characteristics of the open circuit voltage of lithium-ion batteries, which makes the modeling accuracy of the hysteresis model low, thus affecting the SOC estimation

The hysteresis model modeling method based on the Preisach operator used in this paper has been applied in the hysteresis modeling of the open circuit voltage of NiMH batteries, but the hysteresis relationship of the open circuit voltage of lithium-ion batteries is not significant compared with that of NiMH batteries. And there is no symmetry, so that the discrete Preisach model cannot be well applied to lithium-ion batteries

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