Lithium iron phosphate power battery life prediction method

A power battery and life prediction technology, applied in the direction of measuring electricity, measuring devices, measuring electric variables, etc., can solve the difficulties of capacity prediction, cycle life prediction, and increase the difficulty of cycle life prediction of lithium iron phosphate power batteries, etc., to achieve The effect of high practical value

Pending Publication Date: 2020-09-25
CATARC AUTOMOTIVE TEST CENT TIANJIN CO LTD +1
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  • Abstract
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  • Application Information

AI Technical Summary

Problems solved by technology

And those skilled in the art all know that it is difficult to predict the cycle life of the lithium iron phosphate power battery for vehicles, mainly because there is an obvious voltage plateau in the lithium iron phosphate power battery for vehicles during charging and discharging (such as figure 2 As shown), between the discharge platform and the charging platform, the voltage of the battery changes very little, which makes it very difficult to predict the capacity, that is, it increases the difficulty of predicting the cycle life of lithium iron phosphate power batteries

Method used

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  • Lithium iron phosphate power battery life prediction method
  • Lithium iron phosphate power battery life prediction method
  • Lithium iron phosphate power battery life prediction method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Carry out the life test of lithium iron phosphate power battery under real vehicle conditions, record the statistical data of charging capacity and discharging capacity during the cycle; use the statistical data to study the relationship between the charging capacity and discharging capacity of the battery, that is, the sample capacity during the entire life process Efficiency changes, such as image 3 shown.

[0026] from image 3 It can be seen that the Coulombic efficiency of the sample remains unchanged throughout the cycle test, and the decay curves of the charge capacity and discharge capacity basically coincide. Therefore, it is feasible to replace the discharge capacity with the charge capacity.

Embodiment 2

[0028] Comparative analysis of the changing law of the charging capacity and the changing law of the discharging capacity in different voltage ranges. In this example, different charging voltage intervals are selected, including four voltage intervals [3.0-3.3], [3.3-3.4], [3.4-3.6], and [3.3-3.6], and the focus is on analyzing different voltage intervals during the cycle. The change law of the charging capacity corresponding to the interval, such as Figure 4 shown.

[0029] from Figure 4 It can be seen from the figure that the voltage range is different, and the variation law is quite different. The capacity of individual intervals shows a fluctuating upward trend, and the capacity of individual intervals fluctuates in the early stage and slowly declines in the later stage. However, the selection of the voltage range used for life prediction should meet two conditions: continuous decay and high resolution. Therefore, the charging capacity in the voltage range [3.3-3.6] ...

Embodiment 3

[0031] Using the discharge capacity as the life characterization index, analyze the life prediction model, such as Figure 5 shown. Using interval charging capacity as the life characterization index, analyze the life prediction model, such as Image 6 shown. from Figure 5 , Image 6 It can be seen from the figure that the discharge capacity and interval charge capacity of the battery whose capacity retention rate decays to 65% both show a two-stage decay law, with the 880th cycle (capacity retention rate between 85%-90%) as the dividing line. In the first stage, there is a linear decay trend. In the second stage, it is a nonlinear attenuation, and the attenuation law conforms to a quadratic polynomial.

[0032] The actual values ​​of the discharge capacity and interval charge capacity are respectively used as the true value of the life characterization index to analyze the accuracy of the prediction model, as shown in the table below.

[0033]

[0034]

[0035] I...

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Abstract

The invention relates to a lithium iron phosphate power battery life prediction method, which can predict the service life of the lithium iron phosphate power battery for a vehicle, is beneficial to predicting the service life of a new energy vehicle carrying the lithium iron phosphate power battery, and provides accurate vehicle running state information for consumers. According to the predictionmethod provided by the invention, the service life of the lithium iron phosphate power battery can be predicted on the basis of the interval charging capacity provided by the invention under the condition that a complete charging process is not carried out, and the prediction method has extremely high practical value and has high engineering application conditions.

Description

technical field [0001] The invention relates to a method for testing and predicting the service life of a lithium iron phosphate power battery, in particular to a method for predicting the service life of a lithium iron phosphate power battery for vehicles by using interval charging capacity under the charging condition of an electric vehicle. Background technique [0002] With the development and quality improvement of new energy vehicles, under the strong support of the state and the encouragement of industrial policies, new energy vehicles have gradually entered thousands of households, and the market ownership has gradually increased. However, in the actual use process, there are still some areas that need to be improved and improved, including the convenience of charging, the safety of the vehicle and the service life of the vehicle. For ordinary domestic consumers, the service life of new energy vehicles is still a common concern. The key factor that determines the se...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/392
CPCG01R31/392
Inventor 刘仕强王芳白广利林春景马天翼韦振李荣宇陈立铎
Owner CATARC AUTOMOTIVE TEST CENT TIANJIN CO LTD
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