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Method for realizing online estimation of equivalent temperature of lithium ion battery

A lithium-ion battery, equivalent temperature technology, applied in the direction of measuring electricity, measuring electrical variables, measuring devices, etc., can solve problems that affect the safe operation of lithium-ion batteries, have obvious differences, and cannot represent the real temperature of the battery.

Active Publication Date: 2019-04-16
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the temperature of a lithium-ion battery is usually expressed by the temperature of its shell surface or pole. During the charging and discharging process, due to the heat generated by the internal resistance of the battery and electrochemical reactions, the battery will show a certain temperature from the inside to the outside. Gradient distribution, the temperature of the battery surface or pole cannot represent the real temperature of the battery
In a low temperature environment, the difference will become more obvious, which will seriously affect the correctness of the lithium-ion battery state estimation, lead to the normal performance of the lithium-ion battery, and even affect the safe operation of the lithium-ion battery

Method used

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  • Method for realizing online estimation of equivalent temperature of lithium ion battery
  • Method for realizing online estimation of equivalent temperature of lithium ion battery
  • Method for realizing online estimation of equivalent temperature of lithium ion battery

Examples

Experimental program
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Embodiment 1

[0046] figure 1 It is a block flow diagram of the lithium-ion battery equivalent temperature estimation method of embodiment 1 of the present invention, and its specific steps are as follows:

[0047] 1) A 31Ah / 3.7V ternary cylindrical lithium-ion battery was tested at two different test temperatures T 1 =-10℃、T 2 = After standing at 25°C (263K, 298K) for 24 hours, use off-line electrochemical impedance spectroscopy to measure the impedance spectra of the battery at these two different temperatures;

[0048] 2) Using the equivalent circuit model to fit the impedance spectra at two temperatures to obtain the charge transfer resistance R of the battery ct1 =49.49mΩ, R ct2 = 1.19mΩ;

[0049] 3) Separate T 1 , R ct1 and T 2 , R ct2 Substituting into the Arrhenius formula, the coefficients A=8.13E-16 and B=-8347 are obtained, so as to obtain the charge transfer resistance R of the battery under electrochemical impedance spectroscopy analysis ct_0 and the real temperature T...

Embodiment 2

[0088] Image 6 It is a block diagram of applying the lithium-ion battery equivalent temperature estimation method to SOC estimation in Embodiment 2 of the present invention, and its specific steps are as follows:

[0089] 1) Battery SOC refers to the percentage of remaining battery power and available capacity, where the available capacity Q n Will change with the equivalent temperature, through the available capacity Q at different equivalent temperatures n The off-line determination of , the fitting is obtained Q n and equivalent temperature T e The expression is:

[0090]

[0091] Among them, A q =-8.021E7, B q =16.19,y q = 34.49.

[0092] 2) The battery SOC-OCV curve will also change with the equivalent temperature. Through polynomial fitting, the SOC-OCV curve at different battery equivalent temperatures is obtained, expressed as follows:

[0093]

[0094] in, is the equivalent temperature T e under the open circuit voltage, are the polynomial coeffici...

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Abstract

The invention discloses a method for realizing the on-line estimation of the equivalent temperature of a lithium ion battery. The method includes the following steps that: the relationship model of the charge transfer resistance Rct_0 of the lithium ion battery and the real temperature Tr of the battery is established according to electrochemical impedance spectroscopy under different real temperatures of the lithium ion battery; under an actual working condition, an SOC correction factor fs and a current ratio correction factor fi are introduced so as to be used correcting the influence of aSOC and a current ratio on charge transfer resistance respectively, and the relationship model of charge transfer resistance Rct and battery temperature T, which is suitable for the working condition,is established; and the model is substituted into a battery equivalent circuit model, and with the battery temperature T used as a state variable, the extended Kalman filter algorithm is used to estimate the battery temperature T which is used as an equivalent temperature under the working condition of the battery, and therefore, the online estimation of the equivalent temperature of the batteryis realized.

Description

technical field [0001] The invention relates to the technical field of charging and discharging lithium-ion batteries, in particular to a method for realizing online estimation of equivalent temperature of lithium-ion batteries. Background technique [0002] Due to its high operating voltage, long service life, high energy density, large charge and discharge rate, low self-discharge current, and no pollution, lithium-ion batteries have become the power source for electric vehicles, electric ships, and large-scale frequency modulation and peak-shaving energy storage power stations. First choice for battery applications. However, temperature greatly affects the performance and safety of lithium-ion batteries, especially under low temperature conditions, the impedance, open circuit voltage, SOC and other parameters of lithium-ion batteries are particularly sensitive to the influence of temperature. At present, the temperature of a lithium-ion battery is usually expressed by th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/367
Inventor 宋晨路徐涛刘涌
Owner ZHEJIANG UNIV
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