Lithium ion battery SOC estimation method and device

A lithium-ion battery and current technology, applied in the direction of measuring devices, measuring electricity, measuring electrical variables, etc., can solve the problems of increasing estimation error, difficult to guarantee accuracy, and inaccurate estimation, so as to reduce the influence of SOC error and avoid SOC Estimation error, effect of improving SOC estimation accuracy

Active Publication Date: 2020-09-18
KUNMING UNIV OF SCI & TECH
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AI Technical Summary

Problems solved by technology

[0002] At present, the remaining power estimation method of the battery is usually calculated by using the ampere-hour integration method and the open circuit voltage method. This method will be affected by the initial SOC and current acquisition errors, resulting in inaccurate estimation, and as the battery ages and the battery temperature changes, The estimation error will gradually increase, and the accuracy is difficult to guarantee
[0003] In order to reduce the SOC estimation error caused by the current sampling error, the researchers developed an estimation algorithm based on the battery model. This algorithm can effectively reduce the impact of current noise, but it needs to rely on the identification accuracy of the model parameters. When the temperature changes and After the battery ages, the model parameters change greatly, and the ideal estimation accuracy cannot be obtained

Method used

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  • Lithium ion battery SOC estimation method and device
  • Lithium ion battery SOC estimation method and device
  • Lithium ion battery SOC estimation method and device

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Experimental program
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Embodiment 1

[0042] Such as figure 1 As shown, this embodiment provides a method for estimating the SOC of a lithium-ion battery, which can be applied to terminal devices such as battery management systems for electric vehicles. The SOC estimation method of the lithium-ion battery provided in this embodiment includes:

[0043] S101. Obtain in real time the ohmic resistance, polarization internal resistance, polarization capacitance, and open circuit voltage of the lithium-ion battery according to a first preset algorithm.

[0044] In a specific application, the charging and discharging current and terminal voltage of the lithium-ion battery are obtained in real time, and the charging and discharging current and terminal voltage of the lithium-ion battery are calculated through the first preset algorithm to obtain the ohmic resistance, polarization resistance, polarized capacitance and open circuit voltage. Wherein, the first preset algorithm is a parameter identification algorithm based ...

Embodiment 2

[0051] Such as figure 2 As shown, this embodiment is a further description of the method steps in the first embodiment. In this embodiment, step S101 includes:

[0052] S1011. Read the terminal voltage of the lithium ion battery.

[0053] S1012, establishing a first-order equivalent circuit model of the lithium-ion battery.

[0054] In a specific application, the first-order equivalent circuit model of any single battery in a lithium-ion battery pack is as follows: image 3 shown. Among them, E is the terminal voltage, V OCV is the open circuit voltage, R 0 is the ohmic internal resistance, R 1 C 1 Used to describe the polarization characteristics of the battery during charging and discharging, the polarization resistance R 1 The voltage across the V 1 , I is the charging and discharging current. R 0 , R 1 , C 1 is the parameter to be identified. According to the circuit principle, let τ=R 1 C 1 , then the electrical characteristics of the lithium-ion battery...

Embodiment 3

[0080] Such as Figure 4 As shown, this embodiment is a further description of the method steps in the first embodiment. In this embodiment, step S102 includes:

[0081] S1021. Analyzing the historical charging and discharging data of the lithium-ion battery that has reached the service life. The data comes from the laboratory charge and discharge test. During the test process, the battery is fully charged with constant current and constant voltage, and the battery is left to stand for more than 1 hour, then discharged at a constant current to the cut-off voltage of the battery, and then left to stand for more than 1 hour, and the above process is repeated to record the experimental current. , voltage and discharge capacity.

[0082] According to the charging data under different cycle life, the charging time t from the voltage threshold V1 to the voltage threshold V2 under different cycle life is extracted as the input of the least squares support vector machine, and the ma...

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Abstract

The invention is applicable to the technical field of lithium ion batteries, and provides a method and device for improving SOC estimation precision of a lithium ion battery, and the method comprisesthe steps: obtaining the working state of the lithium ion battery at the moment k, and obtaining the maximum discharge capacity of the battery through the calculation of obtained characteristic parameters when the lithium ion battery is in a charging state. And after the lithium ion battery is converted into a discharge state, obtaining current and voltage in the working process of the lithium ionbattery, carrying out online identification, obtaining identification parameters of the lithium ion battery at the moment, calculating terminal voltage, current and identification parameters of the lithium ion battery at the moment k and the obtained maximum discharge capacity, and obtaining the SOC of the lithium ion battery at the moment k. According to the invention, the residual electric quantity of the lithium ion battery can be accurately estimated after the ambient temperature changes and the battery is aged, the efficiency and accuracy of estimating the residual electric quantity of the lithium ion battery are improved, and the anti-interference capability is strong.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and in particular relates to a method and device for estimating the SOC of a lithium-ion battery. Background technique [0002] At present, the remaining power estimation method of the battery is usually calculated by using the ampere-hour integration method and the open circuit voltage method. This method will be affected by the initial SOC and current acquisition errors, resulting in inaccurate estimation, and as the battery ages and the battery temperature changes, The estimation error will gradually increase, and the accuracy is difficult to guarantee. [0003] In order to reduce the SOC estimation error caused by the current sampling error, the researchers developed an estimation algorithm based on the battery model. This algorithm can effectively reduce the impact of current noise, but it needs to rely on the identification accuracy of the model parameters. When the temperatur...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/367G01R31/387G01R31/388G01R31/389
CPCG01R31/367G01R31/387G01R31/388G01R31/389
Inventor 舒星陈峥申江卫颜文胜
Owner KUNMING UNIV OF SCI & TECH
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