CN112038716B - Early warning method for thermal runaway of lithium ion battery pack - Google Patents

Early warning method for thermal runaway of lithium ion battery pack Download PDF

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CN112038716B
CN112038716B CN202010817368.2A CN202010817368A CN112038716B CN 112038716 B CN112038716 B CN 112038716B CN 202010817368 A CN202010817368 A CN 202010817368A CN 112038716 B CN112038716 B CN 112038716B
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early warning
battery pack
voltage difference
thermal runaway
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徐庆庆
丁中强
方磊
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Gotion High Tech Co Ltd
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/42Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4207Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells for several batteries or cells simultaneously or sequentially
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00Computer-aided design [CAD]
    • G06F30/20Design optimisation, verification or simulation
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/052Li-accumulators
    • H01M10/0525Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries

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Abstract

The invention discloses a lithium ion battery pack thermal runaway early warning method which comprises the steps of monitoring data of a battery pack in real time, analyzing and judging the data based on the monitored data to obtain an early warning analysis result, carrying out thermal runaway early warning treatment according to the early warning analysis result, not giving an alarm when thermal runaway danger does not exist, and giving an alarm when the thermal runaway danger exists. The invention can improve the accuracy and response speed of early warning, is beneficial to reminding a user of processing the battery pack possibly with thermal runaway in advance through early warning, and can improve the use safety of the lithium ion battery pack of the electric automobile.

Description

Early warning method for thermal runaway of lithium ion battery pack
Technical Field
The invention relates to the technical field of lithium batteries, in particular to a thermal runaway early warning method for a lithium ion battery pack.
Background
Lithium ion batteries are widely used in electric vehicles due to their high energy density and long cycle life, which are chemical power sources with poor stability and may cause thermal runaway under the conditions of external abuse or defects in their manufacture.
The lithium ion battery is used as a power source of the electric automobile, and can be out of control due to heat generation when the whole automobile is collided and overcharged. The manufacturing defects of the lithium ion battery are the main reason of thermal runaway, and the manufacturing defects are enlarged to generate thermal runaway events in the charging and discharging cyclic use process of the whole vehicle. Although the probability of thermal runaway of the whole vehicle is low, serious personal and property loss can be caused. Under the condition that thermal runaway cannot be completely avoided, early warning of thermal runaway is particularly important, and more time can be won for passengers to escape. The current battery management system only alarms for voltage difference, overhigh voltage, overlow voltage and overhigh temperature, and the threshold values of the alarm items are usually set to be larger, so that thermal runaway early warning cannot be effectively carried out.
Disclosure of Invention
In order to solve the technical problems in the background art, the invention provides a thermal runaway early warning method for a lithium ion battery pack.
The invention provides a lithium ion battery pack thermal runaway early warning method, which comprises the following steps:
s1, acquiring monitoring data of the target battery pack in a specified time window period;
s2, determining the data analysis result of the target battery pack in the specified time window period based on the monitoring data in the specified time window period;
s3, performing early warning analysis on monitoring data and data analysis results of the target battery pack in a specified time window period based on a preset early warning model, and acquiring early warning analysis results of the target battery pack in the specified time window period;
and S4, performing thermal runaway early warning processing based on the early warning analysis result.
Preferably, in S1, the monitoring data includes voltage, current and temperature data of the target battery pack during a prescribed time window.
Preferably, in S2, the data analysis result includes a maximum voltage difference and a minimum voltage difference, a maximum temperature difference, a minimum temperature difference, a current difference, a battery voltage difference entropy and a battery temperature difference entropy of the target battery pack during a specified time window period;
the method for acquiring the data analysis result comprises the following steps:
s21, acquiring voltage difference, temperature difference and current of the target battery pack at the same moment in a specified time window period based on the voltage data, the temperature data and the current data of the target battery pack in the specified time window period;
s22, determining the maximum voltage difference, the minimum voltage difference, the maximum temperature difference, the minimum temperature difference and the current difference of a specified time window period based on the voltage difference and the temperature difference of the target battery pack at the same moment in the specified time window period;
s23, calculating the ratio of the maximum voltage difference to the minimum voltage difference based on the maximum voltage difference and the minimum voltage difference, namely the battery voltage difference entropy;
and S24, calculating the difference value between the maximum temperature difference and the minimum temperature difference based on the maximum temperature difference and the minimum temperature difference, namely the battery temperature difference entropy.
Preferably, in S3, the preset early warning model includes a battery differential pressure threshold, a current differential threshold, a battery differential pressure entropy threshold, and a battery differential temperature entropy threshold;
when the maximum battery voltage difference is larger than a set battery voltage difference threshold value, the current is smaller than a set current difference threshold value, and the battery voltage difference entropy is larger than a set battery voltage difference entropy threshold value or/and the battery temperature difference entropy is larger than a set battery temperature difference entropy threshold value, the obtained early warning analysis result is an alarm.
Preferably, in S3, the preset early warning model is constructed based on the sample thermal runaway state information of the sample battery pack in the thermal runaway time period.
Preferably, in S3, the voltage difference threshold value is 50mV, the current difference threshold value is 100A, the cell voltage difference entropy threshold value is 3, and the cell temperature difference entropy threshold value is 3.
Preferably, in S1, the specified time window period is 5 minutes and is a rolling time.
The invention can monitor the battery pack in real time, analyze and judge based on the monitoring data to obtain the early warning analysis result, and then carry out thermal runaway early warning treatment according to the early warning analysis result, when the thermal runaway danger does not exist, the alarm is not carried out, and when the thermal runaway danger exists, the alarm is carried out. The invention can improve the accuracy and response speed of early warning, is beneficial to reminding a user of processing the battery pack possibly with thermal runaway in advance through early warning, and can improve the use safety of the lithium ion battery pack of the electric automobile.
Drawings
Fig. 1 is a flowchart of a method for early warning of thermal runaway of a lithium ion battery pack according to the present invention.
FIG. 2 is a graph showing the relationship between the battery voltage difference entropy and the voltage difference of the battery pack during the charging process.
Fig. 3 is a graph showing the relationship between the voltage difference entropy and the current of the battery pack during the charging process.
Detailed Description
Referring to fig. 1, the early warning method for thermal runaway of the lithium ion battery pack provided by the invention comprises the following steps:
s1, acquiring monitoring data of the target battery pack in a specified time window period;
s2, determining the data analysis result of the target battery pack in the specified time window period based on the monitoring data in the specified time window period;
s3, performing early warning analysis on monitoring data and data analysis results of the target battery pack in a specified time window period based on a preset early warning model, and acquiring early warning analysis results of the target battery pack in the specified time window period;
and S4, performing thermal runaway early warning processing based on the early warning analysis result.
The invention can monitor the battery pack in real time, analyze and judge based on the monitoring data to obtain the early warning analysis result, and then carry out thermal runaway early warning treatment according to the early warning analysis result, when the thermal runaway danger does not exist, the alarm is not carried out, and when the thermal runaway danger exists, the alarm is carried out. The invention can improve the accuracy and response speed of early warning, is beneficial to reminding a user of processing the battery pack possibly with thermal runaway in advance through early warning, and can improve the use safety of the lithium ion battery pack of the electric automobile.
In order to effectively perform the thermal runaway warning, in the present embodiment, in S1, the monitoring data includes voltage, current and temperature data of the target battery pack within a specified time window period.
In order to effectively perform the warning of thermal runaway, in this embodiment, in S2, the data analysis result includes a maximum voltage difference and a minimum voltage difference, a maximum temperature difference, a minimum temperature difference, a current difference, a battery voltage difference entropy and a battery temperature difference entropy of the target battery pack in a specified time window period;
the method for acquiring the data analysis result comprises the following steps:
s21, acquiring voltage difference, temperature difference and current of the target battery pack at the same moment in a specified time window period based on the voltage data, the temperature data and the current data of the target battery pack in the specified time window period;
s22, determining the maximum voltage difference, the minimum voltage difference, the maximum temperature difference, the minimum temperature difference and the current difference of a specified time window period based on the voltage difference and the temperature difference of the target battery pack at the same moment in the specified time window period;
s23, calculating the ratio of the maximum voltage difference to the minimum voltage difference based on the maximum voltage difference and the minimum voltage difference, namely the battery voltage difference entropy;
and S24, calculating the difference value between the maximum temperature difference and the minimum temperature difference based on the maximum temperature difference and the minimum temperature difference, namely the battery temperature difference entropy.
The voltage difference is the difference between the maximum voltage value and the minimum voltage value at the same moment, and the temperature difference is the difference between the maximum temperature value and the minimum temperature value at the same moment.
Fig. 2 is a graph showing a relationship between a battery voltage difference entropy and a voltage difference in a charging process of the battery pack according to the present invention, and fig. 3 is a graph showing a relationship between a battery voltage difference entropy and a current in a charging process of the battery pack according to the present invention. The sudden increase of the battery differential pressure entropy can represent the situation that partial batteries are in steep drop relative to other batteries, the sudden increase of the battery differential temperature entropy can represent the situation that the partial batteries are in rapid rise relative to other batteries, and the steep drop of the battery voltage and the rapid rise of the battery temperature are the expression forms of the battery physical parameters before the thermal runaway of the battery pack. Therefore, the thermal runaway state of the battery pack can be warned according to the monitoring results of the voltage difference, the current difference, the voltage difference entropy and the temperature difference entropy.
In order to improve the accuracy of the obtained early warning analysis result and thus improve the effectiveness of the thermal runaway early warning, in the embodiment, in S3, the preset early warning model includes a battery pressure difference threshold, a current difference threshold, a battery pressure difference entropy threshold and a battery temperature difference entropy threshold;
when the maximum battery voltage difference is larger than a set battery voltage difference threshold value, the current difference is smaller than a set current difference threshold value, and the battery voltage difference entropy is larger than a set battery voltage difference entropy threshold value or/and the battery temperature difference entropy is larger than a set battery temperature difference entropy threshold value, the obtained early warning analysis result is an alarm.
And when the data analysis result is not in accordance with the preset early warning model, the obtained early warning analysis result is no alarm.
In order to improve the accuracy of the early warning, in this embodiment, in S3, a preset early warning model is constructed based on the sample thermal runaway state information of the sample battery pack in the thermal runaway time period.
In a specific embodiment, in S3, the voltage difference threshold is 50mV, the current difference threshold is 100A, the cell voltage difference entropy threshold is 3, and the cell temperature difference entropy threshold is 3.
In the present embodiment, in S1, the predetermined time window period is 5 minutes and is a scroll time.
Example 1
The method for early warning of thermal runaway of the lithium ion battery pack in the embodiment comprises the following specific steps:
(1) for a ternary lithium ion battery pack running in the market, reading voltage, current and temperature monitoring data within the first 5 minutes every second, wherein the monitoring data is recorded once every second and counts 300 groups of data;
(2) calculating the temperature difference and the voltage difference of 300 groups of data;
(3) searching the maximum value and the minimum value of the temperature difference and the voltage difference according to the calculated temperature difference and the calculated voltage difference;
(4) calculating battery temperature difference entropy and battery pressure difference entropy according to the maximum value and the minimum value of the temperature difference and the voltage difference;
(5) when the voltage difference is more than 50mV, the current difference is less than 100A, and the temperature difference entropy or/and the pressure difference entropy is more than 3, the alarm of the whole vehicle is triggered.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims (4)

1. A lithium ion battery pack thermal runaway early warning method is characterized by comprising the following steps:
s1, acquiring monitoring data of the target battery pack in a specified time window period;
s2, determining the data analysis result of the target battery pack in the specified time window period based on the monitoring data in the specified time window period;
s3, performing early warning analysis on monitoring data and data analysis results of the target battery pack in a specified time window period based on a preset early warning model, and acquiring early warning analysis results of the target battery pack in the specified time window period;
s4, performing thermal runaway early warning treatment based on the early warning analysis result;
in S1, the monitoring data includes voltage, current and temperature data of the target battery pack during a specified time window period;
in S2, the data analysis result includes a maximum voltage difference and a minimum voltage difference, a maximum temperature difference, a minimum temperature difference, a current difference, a battery voltage difference entropy, and a battery temperature difference entropy of the target battery pack during a specified time window period;
the method for acquiring the data analysis result comprises the following steps:
s21, acquiring voltage difference, temperature difference and current of the target battery pack at the same moment in a specified time window period based on the voltage data, the temperature data and the current data of the target battery pack in the specified time window period;
s22, determining the maximum voltage difference, the minimum voltage difference, the maximum temperature difference, the minimum temperature difference and the current difference of a specified time window period based on the voltage difference and the temperature difference of the target battery pack at the same moment in the specified time window period;
s23, calculating the ratio of the maximum voltage difference to the minimum voltage difference based on the maximum voltage difference and the minimum voltage difference, namely the battery voltage difference entropy;
s24, calculating the difference value between the maximum temperature difference and the minimum temperature difference based on the maximum temperature difference and the minimum temperature difference, namely the battery temperature difference entropy;
in S3, the preset early warning model includes a battery pressure difference threshold, a current difference threshold, a battery pressure difference entropy threshold, and a battery temperature difference entropy threshold;
when the maximum battery voltage difference is larger than a set battery voltage difference threshold value, the current is smaller than a set current difference threshold value, and the battery voltage difference entropy is larger than a set battery voltage difference entropy threshold value or/and the battery temperature difference entropy is larger than a set battery temperature difference entropy threshold value, the obtained early warning analysis result is an alarm.
2. The lithium ion battery pack thermal runaway early warning method of claim 1, wherein in S3, the preset early warning model is constructed based on sample thermal runaway state information of the sample battery pack in a thermal runaway time period.
3. The lithium ion battery pack thermal runaway early warning method of claim 1, wherein in S3, the voltage difference threshold is 50mV, the current difference threshold is 100A, the battery voltage difference entropy threshold is 3, and the battery temperature difference entropy threshold is 3.
4. The warning method for thermal runaway of a lithium ion battery pack according to claim 1, wherein in S1, the specified time window period is 5 minutes and is a rolling time.
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CN112793465B (en) * 2021-01-22 2022-09-30 合肥国轩高科动力能源有限公司 Thermal runaway early warning method and application of ternary lithium ion battery system
CN113341332A (en) * 2021-05-25 2021-09-03 三一重机有限公司 Battery thermal runaway early warning method and device, operation machine and electronic equipment
CN114188619B (en) * 2021-11-10 2022-09-16 安徽锐能科技有限公司 Method, system and storage medium for early warning of thermal runaway state of battery
CN114312322B (en) * 2021-12-31 2024-04-12 中国第一汽车股份有限公司 Vehicle detection method and device
CN114415032A (en) * 2022-01-25 2022-04-29 中国汽车工程研究院股份有限公司 Power battery safety detection method, system and storage medium
CN114744734B (en) * 2022-05-25 2023-01-10 深圳市今朝时代股份有限公司 Battery operation control-based battery charging and discharging protection method and management system

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