JP7185741B2 - Method, device, electronic device and medium for prior warning of thermal runaway of power battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to the field of power battery, and in particular to a power battery thermal runaway pre-warning method, apparatus, electronic device and medium.

Over the past ten years, China's domestic new energy vehicle industry has developed rapidly. It was number one in the world for four years in a row. By 2025, China's new energy vehicle sales volume is expected to reach 20% of total vehicle sales volume. Therefore, new energy vehicles are the main driving force for the transformation and upgrading of the automobile industry, and an important development direction in the coming decades.

However, in recent years, the number of fire accidents in new energy vehicles tends to continue to increase. The increasing number of fire safety accidents in different types of vehicles and different application situations is a major impediment to the large-scale popularization and application of electric vehicles. A collective analysis of fire accidents and potential causes for each type of electric vehicle reveals the following typical characteristics as a whole: (1) Accidents occurred in various types of vehicles, including passenger cars, electric buses, and special purpose vehicles. (2) Accidents are highly correlated with the season (environmental temperature), and summer is the season when many accidents occur. (3) The root of the accident has a high correlation with the power battery. Power batteries are regarded as the core power source of electric vehicles, and many fire accidents of electric vehicles are directly related to it. (4) The cause of the accident is ambiguous, and many clues to the accident disappear with the ignition and combustion.

By statistically processing the conditions when an electric vehicle ignites and analyzing the possible causes of accidents, it was found that among the various types of electric vehicle fire accidents, the thermal runaway of the lithium-ion power battery is the most common. found to account for the proportion The process of generating such an accident mainly includes three stages: accumulation of battery cell thermal runaway triggers, occurrence of battery cell thermal runaway, and spread of battery system thermal runaway. In order to improve the safety of the power battery system, the above three stages should be monitored, controlled and prevented step by step. Among them, one of the very important things is to issue an accurate alarm when thermal runaway occurs in the battery and to present a clear signal to the occupants so that the accident can be handled and the occupants can be treated. Reserve enough time for escape.

At present, the determination methods used in the industry to issue battery thermal runaway alarms are mainly based on temperature, voltage, gas, smog, and the like. For example, if the combination of temperature and voltage satisfies the following conditions, it can be determined that thermal runaway has occurred in the battery. Both the voltage drop and temperature change rate exceed their respective predetermined values, and the maximum temperature and temperature change rate both exceed their respective predetermined values. In addition, when the concentration of some gases or smog reaches a certain value, or when an obvious change in gas components such as CO, _H2, etc. in the battery system or a large amount of smog is detected, the battery It can be determined that thermal runaway has occurred in However, when the battery satisfies the above conditions, the battery has already undergone obvious thermal runaway. Therefore, there is a need to develop more efficient means to provide an alarm signal before the battery experiences apparent thermal runaway.

In view of this, the present invention is proposed.

It is an object of the present invention to provide a power battery thermal runaway pre-alarm method, apparatus, electronic device and medium, so as to achieve the effect of presenting an alarm signal before an obvious thermal runaway occurs in the battery.

To achieve the above objects of the present invention, the following technical solutions are adopted.

According to a first aspect, the present invention provides the steps of determining a thermal runaway level of a power battery based on battery voltage, battery temperature and battery expansion force;
giving advance warning of power battery thermal runaway based on the power battery thermal runaway level;
To provide a power battery thermal runaway pre-warning method including:

As a further preferred technical solution, the step of determining the thermal runaway level of the power battery based on the battery voltage, battery temperature and battery expansion force comprises:
determining the thermal runaway level of the power battery based on the battery voltage change value, the battery temperature, the battery temperature change rate, and the battery expansion force change value.

As a further preferred technical solution, the step of determining the thermal runaway level of the power battery based on the battery voltage change value, the battery temperature, the battery temperature change rate, and the battery expansion force change value includes: ,
When at least two of the battery voltage change value, battery temperature, battery temperature change rate, and battery expansion force change value exceed respective predetermined values, it is determined that thermal runaway has occurred in the power battery. and then identifying the thermal runaway level of the power battery based on the type of condition exceeding the predetermined value;
including.

As a further preferred technical solution, the step of determining the thermal runaway level of the power battery based on the battery voltage change value, the battery temperature, the battery temperature change rate, and the battery expansion force change value includes: ,
If the battery expansion force change value exceeds the expansion force change value threshold and the battery voltage change value exceeds a predetermined percentage of the battery initial voltage, the thermal runaway level of the power battery is identified as level 1. and
identifying the thermal runaway level of the power battery as level 2 if the battery expansion force change value exceeds the expansion force change value threshold value and the battery temperature exceeds the battery temperature threshold value;
If the battery expansive force change value exceeds the expansive force change value threshold value, the battery temperature change rate exceeds the temperature change rate threshold value, and the exceeding time exceeds the time threshold value, the thermal runaway of the power battery occurs. identifying the level as level 3;
The value of change in expansion force of the battery exceeds the threshold value of change in expansion force, the value of change in battery voltage exceeds a predetermined percentage of the initial voltage of the battery, the rate of change in battery temperature exceeds the threshold value of temperature change, and , if the time exceeded is greater than the time threshold, identifying the thermal runaway level of the power battery as level 4;
The change value of the expansion force of the battery exceeds the threshold value of change value of expansion force, the battery temperature exceeds the threshold value of battery temperature, the rate of change of battery temperature exceeds the threshold value of temperature change rate, and the time when it exceeds the threshold is time. if higher than the threshold, identifying the thermal runaway level of the power battery as level 5;
including.

As a more preferred technical solution, the threshold value of the expansion force change value is 1500-2500N.

As a more preferred technical solution, the initial voltage of the predetermined percentage battery is 15%-25% of the initial voltage of the battery.

As a more preferred technical solution, the threshold temperature change rate is 1-5° C./s.

According to a second aspect, the present invention provides a power battery thermal runaway level determination module for determining a power battery thermal runaway level based on battery voltage, battery temperature and battery expansion force;
a thermal runaway pre-alarm module for performing a power battery thermal runaway pre-alarm based on the power battery thermal runaway level;
provides a pre-alarm device for power battery thermal runaway including:

According to a third aspect, the invention provides at least one processor;
a memory communicatively coupled with the at least one processor;
including
the memory stores instructions executable by the at least one processor;
the instructions cause the at least one processor to perform the method, whereby the at least one processor executes the instructions;
Provide electronic devices.
According to a fourth aspect, the invention provides a medium having computer instructions stored thereon for causing a computer to perform the above method.

Beneficial effects of the present invention are as follows.

The power battery thermal runaway pre-warning method provided by the present invention is to identify the power battery thermal runaway level based on battery voltage, battery temperature and battery expansion force, and further based on the power battery thermal runaway level. to give advance warning of power battery thermal runaway. As a result of research, the inventors of the present invention found that when thermal runaway occurs in a battery, gas is generated inside the battery and the positive/negative electrodes expand. Or when it is lower than the opening pressure of the cylindrical battery relief valve and the breaking pressure of the pouch battery cell aluminum laminate film, it appears as a continuous increase in expansion force, and the change in the characteristics is usually battery voltage and battery temperature. I found that it is faster than change. In addition, obtaining the expansion force is relatively convenient and accurate, and obtaining the temperature is inconvenient and slower than the expansion force, and there is a certain delay. Appears in Therefore, the present invention combines battery voltage, battery temperature, and battery expansion force, and specifically provides four values: battery voltage change value, battery temperature, battery temperature change rate, and battery expansion force change value. Five points, and five levels of thermal runaway levels based on the order in which these four points appear when thermal runaway actually occurs, the importance, the degree of thermal runaway, and the accuracy of the alarm. Furthermore, according to the level, a corresponding advance warning of thermal runaway is given.

The method can effectively determine whether the power battery has thermal runaway or not, issue a warning signal before the battery has obvious thermal runaway, and provide different warnings for different thermal runaway levels. It can be carried out. The user can take corresponding countermeasures for different thermal runaway levels.

FIG. 1 is a flow chart of a power battery thermal runaway pre-warning method according to an embodiment of the present invention. FIG. 2 is a temperature, voltage and expansion force change diagram during thermal runaway due to overcharge of the 25 Ah square hard case lithium iron phosphate/graphite battery of the present invention. FIG. 3 is a graph showing changes in temperature, voltage and expansion force during thermal runaway due to overcharging of the 37 Ah square hard case Ni _0.5 Co _0.2 Mn _0.3 ternary material/graphite battery of the present invention. FIG. 4 is a change diagram of temperature, voltage and expansion force in thermal runaway due to heating of a 37 Ah square hard case Ni _0.5 Co _0.2 Mn _0.3 ternary system material/graphite battery of the present invention. FIG. 5 is a structural schematic diagram of a power battery thermal runaway pre-warning device according to an embodiment of the present invention. FIG. 6 is a structural schematic diagram of an electronic device according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to embodiments, but as can be understood by those skilled in the art, the following embodiments are not intended to limit the scope of the present invention, but merely the present invention. It is intended to illustrate the invention. If specific conditions are not specified in the embodiments, general conditions or conditions recommended by manufacturers are used.

FIG. 1 is a flow chart of the power battery thermal runaway preliminary warning method according to the present embodiment, which is applied to the power battery thermal runaway preliminary warning in the normal standing state, charging state and discharging state. be. The method may be performed by a power battery thermal runaway pre-warning device. The apparatus may be constructed in software and/or hardware and typically integrated into an electronic device.

As shown in FIG. 1, the present embodiment provides a power battery thermal runaway pre-warning method including the following steps.

S110
A thermal runaway level of the power battery is determined based on battery voltage, battery temperature, and battery expansion force.

It should be noted that the "battery voltage" above refers to the difference between the positive electrode potential and the negative electrode potential of the battery. The battery voltage can be collected by a voltage sensor.

The "battery temperature" refers to the temperature of the surface of the battery, and includes at least one of the temperature of the battery positive electrode, the temperature of the battery negative electrode, and the temperature of the battery case. For example, "battery temperature" is the temperature of the battery positive electrode, the temperature of the battery negative electrode, the temperature of the battery case, the temperature of the battery positive electrode + the temperature of the battery negative electrode, the temperature of the battery negative electrode + the temperature of the battery case, the temperature of the battery positive electrode + the battery case. or the temperature of the battery positive electrode + the temperature of the battery negative electrode + the temperature of the battery case, preferably the temperature of the battery positive electrode + the temperature of the battery negative electrode + the temperature of the battery case. If the battery temperature is two or more of the temperature of the battery positive electrode, the temperature of the battery negative electrode, and the temperature of the battery case, priority is given to the higher temperature value. The battery temperature can be acquired by a temperature sensor.

The "expansion force of the battery" is the pressure applied to the case side surface of the battery cells in the battery module or battery pack. The expansion force of the battery can be obtained by a pressure sensor.

Optionally, the step of determining a thermal runaway level of the power battery based on battery voltage, battery temperature and battery expansion force comprises:
identifying the thermal runaway level of the power battery as level 1 if the expansion force of the battery exceeds the expansion force threshold;
identifying the thermal runaway level of the power battery as level 2 if the battery voltage exceeds the battery voltage threshold;
identifying the thermal runaway level of the power battery as level 3 if the battery temperature exceeds the battery temperature threshold;
including.

The expansion force threshold can be set to a corresponding value according to the state of the battery. The battery voltage threshold is set to a corresponding value according to the model number and type of the battery. The battery temperature threshold is set to a corresponding numerical value according to the maximum operating temperature specified by the battery manufacturer, for example, 75-85.degree.

In the above method of identifying thermal runaway in power batteries, if only the battery temperature (i.e., the current temperature of the battery) is considered, there is also a risk of thermal runaway if the battery temperature changes too quickly in practice. Thus, in one preferred embodiment, the step of determining the thermal runaway level of the power battery based on battery voltage, battery temperature, and battery expansion force comprises:
determining a thermal runaway level of the power battery based on the change in battery voltage, the battery temperature, the rate of change in battery temperature, and the change in expansion force of the battery.

As a point to be explained, the above-mentioned "battery voltage change value" refers to the difference between the current voltage of the battery and the voltage of the battery immediately before, and the change value of the battery voltage is obtained by a voltage sensor. can do.

The "battery temperature change rate" refers to the instantaneous change rate of the surface temperature of the battery. The "battery temperature change rate" includes at least one of a battery positive electrode temperature change rate, a battery negative electrode temperature change rate, and a battery case temperature change rate. For example, the "rate of battery temperature change" is the rate of change in temperature of the positive electrode, the rate of change in temperature of the negative electrode, the rate of change in temperature of the battery case, the rate of change in temperature of the positive electrode + the rate of change in temperature of the negative electrode. , battery negative electrode temperature change rate + battery case temperature change rate, battery positive electrode temperature change rate + battery case temperature change rate, or battery positive electrode temperature change rate + battery negative electrode temperature change rate + rate of change of battery case temperature. If the rate of battery temperature change is two or more of the rate of change in temperature of the battery positive electrode, the rate of change in temperature of the battery negative electrode, and the rate of change in temperature of the battery case, the rate of change in temperature of the higher one Prioritize speed values. The change speed of the battery temperature can be acquired by a temperature sensor.

The above-mentioned "value of change in expansion force of the battery" refers to the value of the difference between the current expansion force of the battery and the initial expansion force of the battery. The initial expansion force of the battery refers to the normal expansion force of the battery when an abnormality such as thermal runaway does not occur in a different state. The different states include a normal left state, a charged state, a discharged state, and the like. The initial expansion force of the battery can take a corresponding value according to the model number and type of the battery. In addition, the initial expansion force generally increases as the aging condition of the battery becomes more serious. In general, the change value of the expansion force of the battery due to the change of the environmental temperature is 20 to 80N under the normal standing condition. Under normal charging and discharging conditions, the variation of the expansion force of the battery is 100-1000N.

The step of determining the thermal runaway level of the power battery based on the battery voltage change value, the battery temperature, the battery temperature change rate, and the battery expansion force change value,
identifying the thermal runaway level of the power battery as level 1 if the change in expansion force of the battery exceeds the threshold change in expansion force;
identifying the thermal runaway level of the power battery as level 2 if the change in battery pressure exceeds a threshold change in battery pressure;
identifying the thermal runaway level of the power battery as level 3 if the battery temperature exceeds the battery temperature threshold or the battery temperature change rate exceeds the temperature change rate threshold;
may contain

Due to the uncertainty of the thermal runaway mode when the power battery actually experiences thermal runaway, usually not only one of them exceeds the threshold, but in order to further improve the accuracy of the judgment, It is preferable to: That is, in one preferred embodiment of the present embodiment, thermal runaway of the power battery is determined based on the battery voltage change value, battery temperature, battery temperature change rate, and battery expansion force change value. The step of identifying the level is
When at least two of the battery voltage change value, battery temperature, battery temperature change rate, and battery expansion force change value exceed respective predetermined values, it is determined that thermal runaway has occurred in the power battery. and thereafter determining a thermal runaway level of the power battery based on the type of condition exceeding the predetermined value.

As a point to explain,
The above "at least two" refers to at least two of the battery voltage change value, the battery temperature, the battery temperature change rate, and the battery expansion force change value. For example, "at least two" are battery voltage change value + battery temperature, battery temperature change rate + battery expansion force change value, battery temperature + battery temperature change rate, battery voltage change value + battery temperature + Battery temperature change rate, battery temperature + battery temperature change rate + battery expansion force change value, or battery voltage change value + battery temperature + battery temperature change rate + battery expansion force change value, etc. .

The above-mentioned "type of condition" refers to the above-mentioned battery voltage change value, battery temperature, battery temperature change rate, and battery expansion force change value. be done.

When at least two of the battery voltage change value, battery temperature, battery temperature change rate, and battery expansion force change value exceed respective predetermined values, thermal runaway occurs in the power battery. and then identifying the thermal runaway level of the power battery based on the type of condition exceeding the predetermined value,
If the battery expansion force change value exceeds the expansion force change value threshold and the battery voltage change value exceeds a predetermined percentage of the battery initial voltage, the thermal runaway level of the power battery is identified as level 1. and
identifying the thermal runaway level of the power battery as level 2 if the battery expansion force change value exceeds the expansion force change value threshold value and the battery temperature exceeds the battery temperature threshold value;
If the battery expansive force change value exceeds the expansive force change value threshold value, the battery temperature change rate exceeds the temperature change rate threshold value, and the exceeding time exceeds the time threshold value, the thermal runaway of the power battery occurs. identifying the level as level 3;
When the battery voltage change value exceeds a predetermined percentage of the battery initial voltage, the battery temperature change rate exceeds the temperature change rate threshold, and the exceeding time is higher than the time threshold, the thermal runaway level of the power battery is determined. identifying level 4;
may contain

Determining the thermal runaway level of the power battery based on the above conditions will match the actual situation and give a more accurate warning than the thermal runaway level determined using only one index. However, the conditions for specifying the runaway level still need improvement in terms of reflecting the degree of thermal runaway and the accuracy of the warning. For this reason, in one preferred embodiment of the present embodiment, based on the battery voltage change value, battery temperature, battery temperature change rate, and battery expansion force change value, the heat of the power battery is calculated. The step of identifying the runaway level includes:
If the battery expansion force change value exceeds the expansion force change value threshold and the battery voltage change value exceeds a predetermined percentage of the battery initial voltage, the thermal runaway level of the power battery is identified as level 1. and
identifying the thermal runaway level of the power battery as level 2 if the battery expansion force change value exceeds the expansion force change value threshold value and the battery temperature exceeds the battery temperature threshold value;
If the battery expansive force change value exceeds the expansive force change value threshold value, the battery temperature change rate exceeds the temperature change rate threshold value, and the exceeding time exceeds the time threshold value, the thermal runaway of the power battery occurs. identifying the level as level 3;
The value of change in expansion force of the battery exceeds the threshold value of change in expansion force, the value of change in battery voltage exceeds a predetermined percentage of the initial voltage of the battery, the rate of change in battery temperature exceeds the threshold value of temperature change, and , if the time exceeded is greater than the time threshold, identifying the thermal runaway level of the power battery as level 4;
The change value of the expansion force of the battery exceeds the threshold value of change value of expansion force, the battery temperature exceeds the threshold value of battery temperature, the rate of change of battery temperature exceeds the threshold value of temperature change rate, and the time when it exceeds the threshold is time. if higher than the threshold, identifying the thermal runaway level of the power battery as level 5;
may contain

This preferred embodiment considers the degree of thermal runaway after thermal runaway actually occurs in the power battery, issues a warning according to the level of the degree of thermal runaway, and clarifies the accuracy and reliability of the warning. can be improved.

As a point to explain,
The "initial voltage" refers to the voltage when the battery is fully charged.

The “threshold value of change in expansive force” is preferably 1500 to 2500N. The threshold value of the expansion force change value is typically, but not limited to, 1500N, 1600N, 1700N, 1800N, 1900N, 2000N, 2100N, 2200N, 2300N, 2400N or 2500N. The inventor conducted a large amount of research and found that when the "threshold value of change in expansion force" exceeds the above range, the risk of thermal runaway of the battery is determined with high probability. If the threshold is too small, the threshold will be exceeded due to normal expansion force changes inside a general battery, and the existence of thermal runaway cannot be determined sufficiently. If the threshold is too large, the battery will experience significant thermal runaway before the threshold is exceeded. Therefore, if the determination is made based on an excessively large threshold value, the timing of issuing the warning will surely be delayed, which is not suitable for issuing an early warning.

Further, the “predetermined percentage of the initial voltage of the battery” is preferably 15% to 25% of the initial voltage of the battery. The "predetermined percentage of the cell's initial voltage" is typically 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24% of the cell's initial voltage. % or 25%, but not limited thereto. If the "predetermined percentage of battery initial voltage" exceeds the above range, the change in battery voltage is large, indicating a high risk of thermal runaway. If the "initial voltage of a predetermined percentage of the battery" is set too low, the threshold will be exceeded due to voltage changes due to normal operation of the battery, and battery thermal runaway cannot be determined. If the "predetermined percentage of battery initial voltage" is set too high, the battery will experience apparent thermal runaway before exceeding the threshold. Therefore, if the determination is made based on an excessively large threshold value, the timing of issuing the warning will surely be delayed, which is not suitable for issuing an early warning.

The “threshold of temperature change rate” is preferably 1 to 5° C./s. The "temperature change rate threshold" is typically 1° C./s, 2° C./s, 3° C./s, 4° C./s or 5° C./s, but is not limited thereto. If the "temperature change speed threshold" exceeds the above range, it indicates that the temperature change of the battery is rapid and the risk of thermal runaway is high. If the "threshold for temperature change rate" is set too low, the threshold will be exceeded due to temperature changes during normal operation of the battery, and battery thermal runaway cannot be determined. If the "threshold for temperature change rate" is set too high, the threshold will be exceeded after obvious thermal runaway occurs in the battery. Therefore, if the determination is made based on an excessively large threshold value, the timing of issuing the warning will surely be delayed, which is not suitable for issuing an early warning.

The "time threshold" is preferably between 2.5 and 3.5s. The "time threshold" is typically 2.5s, 2.6s, 2.7s, 2.8s, 2.9s, 3s, 3.1s, 3.2s, 3.3s, 3.4s or 3.5s, but not limited to these.

S120
Based on the thermal runaway level of the power battery, a preliminary warning of power battery thermal runaway is provided.

The advance warning of thermal runaway in this embodiment indicates that the degree of thermal runaway gradually increases as the thermal runaway level rises. When actually issuing the alarm, different thermal runaway levels can employ different alarm schemes. For example, if a beep is used for the alarm, different tones can represent different thermal runaway levels. When using lights for the alarm, different colors of lights can represent different levels of thermal runaway. This embodiment does not particularly limit the specific format of the alert, and any one format that can be implemented in this field may be used. For example, an alarm by sound, an alarm by lamp light, an alarm by sound and lamp light, or a vibration alarm can be used.

The inventors of the present invention systematically studied the thermal runaway of power batteries using the following method, and confirmed the importance of the expansion force of the battery in the battery thermal runaway.
1) Perform a thermal runaway test of the power battery. In order to more realistically simulate situations in which thermal runaway occurs in batteries in actual use, overcharging, external heating, and the like are used as methods of causing thermal runaway in batteries.

2) Measure characteristic parameters (including battery temperature, voltage, and expansion force) in the thermal runaway process of the battery. The battery temperature includes the temperature of the positive/negative tabs of the battery and the temperature of the case, which is obtained by the temperature sensor. The voltage is the positive/negative terminal voltage of the battery and is obtained by a voltage sensor. The expansion force of the battery is the expansion force of the side surface of the rectangular hard case or pouch battery cell, and is obtained by a pressure sensor. By arranging one pressure sensor in a single battery module in the battery system, the expansion force of the entire battery module can be obtained. Also, by arranging a pressure sensor on the side surface of a single battery cell, it is possible to obtain the expansion force value for each battery cell. 2, 3 and 4 are the measurement results of temperature, voltage and expansion force during the thermal runaway process generated by different methods for batteries of different material systems.

A specific 25 Ah prismatic hard case lithium iron phosphate/graphite lithium ion battery and a specific 37 Ah prismatic hard case Ni _0.5 Co _0.2 Mn _0.3 ternary material/graphite battery is used to measure thermal runaway under overcharge conditions.

1. Experimental measurement 1) According to the product specification, the power battery was subjected to discharge capacity measurement, and then the power battery cell was fully charged.

2) A 2C current rate was used to overcharge the battery cells and perform thermal runaway measurements. We simulated an abuse situation that occurs when a functional safety failure or voltage signal collection failure occurred in the BMS of the battery system of an electric vehicle, and recorded the voltage, temperature, and expansion force of the battery cell. The sampling frequency was 100 Hz, and battery changes were observed with a camera.
3) When the battery under test showed obvious thermal runaway characteristics (eg, relief valve relief, smoke, fire or explosion), charging of the battery was stopped. In this measurement, after observing that the relief valve generated relief in the battery and started to emit smoke at the same time, the battery continued to emit smoke even after the charging of the battery was stopped. The data acquisition device was operated continuously until no further phenomena occurred, and data recording was stopped when the temperature measured by all the temperature sensors was less than 50°C.

2. The experiment was terminated, the measurement data were saved, and the experimental samples were processed.

3. Data Analysis As can be seen from the measured data shown in FIG. 2, after the start of the test, as the voltage of the 25 Ah square hard case lithium iron phosphate/graphite based battery gradually increased, the expansion force of the battery increased rapidly. Within 150s, the change value of expansion force reached 1500N, at which time the battery temperature was only 27°C. When the relief valve was opened, the expansion force reached its maximum value. After that, after opening the relief valve, the expansion force of the battery obviously decreased. Since various side reactions inside the battery occurred continuously, a large amount of gas and smog was generated, and the expansion force was maintained at about 2800N. After the battery was completely cut off, the temperature stopped rising, the voltage dropped to zero, and the expansion force also gradually disappeared, dropping to zero.

As can be seen from the comparison of changes in the signals of battery voltage, temperature, expansion force, etc., the point at which the expansion force begins to significantly increase is earlier than the change in temperature. Since there is a time of 150 seconds from the point at which the change in expansion force exceeds the range of change in expansion force corresponding to normal charging and discharging until thermal runaway occurs in the battery, the change in expansion force of the battery is used to evaluate the battery. A thermal runaway alarm can be provided.

As can be seen from _the measurement _data shown in FIG _. Both the expansion force and the temperature of the battery started to increase, and the change value of the expansion force became 1500N at 650s. At this time, the battery temperature was only 24°C. When the relief valve was opened, the expansion force reached a maximum value of 4958N. After that, after the relief valve was opened, the expansion force of the battery gradually decreased, and after continuing for a certain period of time, the expansion force decreased to zero, and along with this process, the battery temperature gradually decreased.

As can be seen from the comparison of the changes in the signals of battery voltage, temperature, expansion force, etc., similar to lithium iron phosphate/graphite material system batteries, the point at which the expansion force begins to increase significantly is higher than the change in temperature. quick. When the expansion force change value exceeds the expansion force change range corresponding to normal charging and discharging, there is a time of 260 seconds until thermal runaway occurs in the battery. An effective warning of runaway can be provided.

Taking a 37 Ah square hard case Ni _0.5 Co _0.2 Mn _0.3 ternary material/graphite lithium ion battery as an example, thermal runaway measurement was performed under heating conditions.

1. Experimental measurement 1) According to the product specification, the power battery was subjected to discharge capacity measurement, and then the power battery cell was fully charged.

2) An external heating method (an electric heater is used to heat the battery, and the electric heater is powered by a programmable power supply) was adopted to heat the battery cell and perform thermal runaway measurement. The power of the heater was set to 800 W to simulate the heat diffusion scene caused by self-heating runaway caused by defects inside some battery cells in the battery system of an electric vehicle. The voltage, temperature and expansion force of the battery cells in the process were recorded, the sampling frequency was 100 Hz, and the battery changes were observed with a camera.

3) The heating power supply was turned off if the battery under test exhibited obvious thermal runaway characteristics (eg relief valve relief, smoke, fire or explosion). In this measurement, after observing that the relief valve of the battery started to emit smoke at the same time, the external power source for the electric heater was turned off, but the battery continued to emit smoke. The data collection device was operated continuously until no further phenomena occurred, and data recording was stopped when the temperature measured by all the temperature sensors was less than 50°C.

2. The experiment was terminated, the measurement data were saved, and the experimental samples were processed.

3. Data Analysis As can be seen from the measurement data shown in FIG. 4, after the start of the test, due to the action of the external electric heater, as the temperature of the ternary material/graphite battery increased, the expansion force of the battery also increased rapidly. After 400 s from the start of the test, the expansion force of the battery increased at a faster rate, and after 510 s, the change value of the expansion force exceeded 1500 N, but the battery voltage still remained unchanged at this time. At 602 s, the battery voltage became 0 V due to an internal short circuit.

As can be seen from the comparison of changes in the signals of battery voltage, temperature, expansion force, etc., the point at which the expansion force begins to significantly increase is earlier than the change in voltage. Even if the expansion force change value exceeds the expansion force change range corresponding to normal charging and discharging, there is still 92 seconds until a short circuit occurs inside the battery. Therefore, an early warning of battery thermal runaway can be realized using the change value of the expansion force of the battery.

FIG. 5 is a structural schematic diagram of the power battery thermal runaway early warning device according to the present embodiment, which is applied to the power battery thermal runaway preliminary warning in the normal standing state, charging state and discharging state of the power battery. be done. The apparatus may be constructed by software and/or hardware and is typically integrated into an electronic device.

As shown in FIG. 5, the present embodiment provides a power battery thermal runaway pre-warning device including the following modules:

The power battery thermal runaway level determination module 501 is used to determine the power battery thermal runaway level based on the battery voltage, battery temperature and battery expansion force.
The power battery thermal runaway level identification module 501 includes:
battery expansion force change value comparison means for comparing the expansion force change value of the battery with a threshold value of the expansion force change value;
battery voltage change value comparison means for comparing the change value of the battery voltage and the initial voltage of the battery in a predetermined ratio;
battery temperature comparison means for comparing the battery temperature with a battery temperature threshold;
battery temperature change rate comparison means for comparing the battery temperature change rate with a temperature change rate threshold;
thermal runaway level identifying means for identifying a thermal runaway level based on the comparison result of the comparing means;
is preferably included.

determining a thermal runaway level of the power battery based on the battery voltage, the battery temperature and the expansion force of the battery;
If the battery expansion force change value exceeds the expansion force change value threshold and the battery voltage change value exceeds a predetermined percentage of the battery initial voltage, the thermal runaway level of the power battery is identified as level 1. and
identifying the thermal runaway level of the power battery as level 2 if the battery expansion force change value exceeds the expansion force change value threshold value and the battery temperature exceeds the battery temperature threshold value;
When the battery expansion force change value exceeds the expansion force change value threshold value, the battery temperature change rate exceeds the temperature change rate threshold value, and the exceeding time is higher than the time threshold value, the thermal runaway level of the power battery is determined. identifying level 3;
The value of change in expansion force of the battery exceeds the threshold value of change in expansion force, the value of change in battery voltage exceeds a predetermined percentage of the initial voltage of the battery, the rate of change in battery temperature exceeds the threshold value of temperature change, and , if the time exceeded is greater than the time threshold, identifying the thermal runaway level of the power battery as level 4;
The change value of the expansion force of the battery exceeds the threshold value of change value of expansion force, the battery temperature exceeds the threshold value of battery temperature, the rate of change of battery temperature exceeds the threshold value of temperature change rate, and the time when it exceeds the threshold is time. if higher than the threshold, identifying the thermal runaway level of the power battery as level 5;
is preferably included.

The threshold value of the expansion force change value is preferably 1500 to 2500N.

The initial voltage of the predetermined percentage of cells is preferably between 15% and 25% of the initial voltage of the cells.

The threshold temperature change rate is preferably 1 to 5° C./s.

The thermal runaway pre-alarm module 502 is used to provide a power battery thermal runaway pre-alarm based on the power battery thermal runaway level.

The power battery thermal runaway pre-warning device is used to implement the power battery thermal runaway pre-warning method in the embodiment of the present invention, and is useful with at least functional modules corresponding to the power battery thermal runaway pre-warning method. effect.

As shown in FIG. 6, embodiments of the present invention include:
at least one processor;
a memory communicatively coupled with the at least one processor;
including
The memory stores instructions executable by the at least one processor, the instructions causing the at least one processor to perform the method, thereby causing the at least one processor to perform the instructions. is executed,
Provide electronic devices.

At least one processor in the electronic device is capable of executing the method, thus having at least the same advantages as the method.

As a possible option, the electronic device further includes an interface for connecting each component, the interface including a high speed interface and a low speed interface. Each component is interconnected by a different bus and may be mounted on a common motherboard or otherwise as desired. A processor can process instructions that are executed within the electronic device. The instructions may be instructions stored in memory or instructions to display graphical information in a GUI (Graphical User Interface) on an external input/output device (e.g., a display device coupled to the interface) in memory. including. In other embodiments, multiple processors and/or multiple buses may be used, along with multiple memories and multiple memories, where appropriate. Similarly, it may be connected to multiple electronic devices, each device (eg, as a server array, blade server cluster, or multi-processor system) providing some necessary operation. In FIG. 6, one processor 601 is taken as an example.

Memory 602 is a computer-readable storage medium that stores software programs, computer-executable programs and modules, such as program instructions/modules corresponding to the power battery thermal runaway pre-warning method in embodiments of the present invention (e.g., power It may be used to store the power battery thermal runaway level identification module 501 and the thermal runaway pre-alarm module 502) in the battery thermal runaway pre-alarm device. The processor 601 executes the software programs, instructions and modules stored in the memory 602 to perform various functional applications and data processing of the device, i.e. to implement the power battery thermal runaway pre-warning method described above. do.

The memory 602 may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, application programs required for at least one function, and a data storage area. may store data or the like created according to the use of the terminal. Memory 602 may also include high speed random access memory and may also include non-volatile memory, such as at least one magnetic disk memory, flash memory, or other non-volatile solid-state memory. In some examples, memory 602 may also include memory remotely located relative to processor 601, and these remote memories may be connected to the device via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

The electronic device may further include an input device 603 and an output device 604 . The processor 601, the memory 602, the input device 603, and the output device 604 may be connected by a bus or other methods, and in FIG. 6, the bus connection is taken as an example.

The input device 603 receives input numerical or textual information, and the output device 604 may include a display device, an auxiliary lighting device (eg, LED), a tactile feedback device (eg, vibration motor), and the like. Such display devices may include, but are not limited to, liquid crystal displays (LCDs), light emitting diode displays (LEDs), and plasma displays. In some embodiments, the display device may be a touch screen.

Embodiments of the present invention further provide a medium having computer instructions stored thereon for causing a computer to perform the above method. The computer instructions on the medium are used to cause a computer to perform the method, thus having at least the same advantages as the method.

Any combination of one or more computer readable media may be employed as a medium in the present invention. The medium may be a computer readable signal medium or a computer readable storage medium. The medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device, or a combination of any of the foregoing. Further specific examples of media (non-exhaustive list) are electrical connections with one or more leads, portable computer disks, hard disks, random access memory (RAM), read only memory (ROM), Erasable programmable read only memory (EPROM) or flash memory, fiber optics, portable compact disc read only memory (CD-ROM), optical memory, magnetic memory, or any suitable combination of the foregoing. In this specification, a medium may be a tangible medium that contains or stores a program, and the program may be used in an instruction execution system, apparatus, or device, or may be used in combination with them. good.

A computer readable signal medium, which may include a data signal propagating in baseband or as part of a carrier wave, carries computer readable program code. The data signals thus propagated may take many forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the foregoing. A computer readable signal medium may also be any computer readable medium other than a computer readable storage medium for use in an execution system, apparatus or device. or any program for use in conjunction therewith may be transmitted, propagated or transmitted.

Program code embodied on a computer readable medium may be transmitted over any suitable medium including wireless, electrical wires, fiber optic cables, optical cables, Radio Frequency (RF), etc., or any suitable combination of the above. may be, but are not limited to.

Computer program code for carrying out operations of the present invention may be written in one or more programming languages, or combinations thereof, including target-oriented programming languages such as Java, Smalltalk, C++, and in general any procedural programming language, such as the "C" language or similar programming language. Program code may run on the user's computer, partly on the user's computer, as a separate software package, partly on the user's computer and partly on a remote computer. or run entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user computer by any kind of network (including a local area network (LAN) or a women's action network (WAN)) or may be connected to an external computer (e.g. an Internet service provider). (connected by the Internet using the Internet).

It will be appreciated that steps may be rearranged, added, or deleted using the various types of procedures set forth above. For example, each step described in this application can be performed in parallel or sequentially, or can be performed in a different order, as long as the desired results of the technical solutions disclosed in this application can be achieved. not limited here.

Although the invention has been illustrated and described using specific embodiments, it will be appreciated that various changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended that the appended claims cover all such modifications and variations that fall within the scope of this invention.

501 Power Battery Thermal Runaway Level Identification Module 502 Thermal Runaway Pre-warning Module 601 Processor 602 Memory 603 Input Device 604 Output Device

Claims (8)

When at least two of the battery voltage change value, battery temperature, battery temperature change rate, and battery expansion force change value exceed respective predetermined values, it is determined that thermal runaway has occurred in the power battery. determining, and thereafter identifying the thermal runaway level of the power battery based on the type of condition exceeding the predetermined value;
giving advance warning of power battery thermal runaway based on the power battery thermal runaway level;
A pre-warning method for thermal runaway of a power battery, comprising: The step of determining the thermal runaway level of the power battery based on the battery voltage change value, the battery temperature, the battery temperature change rate, and the battery expansion force change value,
If the battery expansion force change value exceeds the expansion force change value threshold and the battery voltage change value exceeds a predetermined percentage of the battery initial voltage, the thermal runaway level of the power battery is identified as level 1. and
identifying the thermal runaway level of the power battery as level 2 if the battery expansion force change value exceeds the expansion force change value threshold value and the battery temperature exceeds the battery temperature threshold value;
If the battery expansive force change value exceeds the expansive force change value threshold value, the battery temperature change rate exceeds the temperature change rate threshold value, and the exceeding time exceeds the time threshold value, the thermal runaway of the power battery occurs. identifying the level as level 3;
The value of change in expansion force of the battery exceeds the threshold value of change in expansion force, the value of change in battery voltage exceeds a predetermined percentage of the initial voltage of the battery, the rate of change in battery temperature exceeds the threshold value of temperature change, and , if the time exceeded is greater than the time threshold, identifying the thermal runaway level of the power battery as level 4;
The change value of the expansion force of the battery exceeds the threshold value of change value of expansion force, the battery temperature exceeds the threshold value of battery temperature, the rate of change of battery temperature exceeds the threshold value of temperature change rate, and the time when it exceeds the threshold is time. if higher than the threshold, identifying the thermal runaway level of the power battery as level 5;
The power battery thermal runaway pre-warning method according to claim 1 , characterized by comprising: The method for pre-warning thermal runaway of a power battery according to claim 2 , characterized in that the threshold value of the expansion force change value is 1500-2500N. The power battery thermal runaway pre-warning method according to claim 3 , characterized in that the predetermined percentage of battery initial voltage is between 15% and 25% of the battery initial voltage. The power battery thermal runaway advance warning method according to claim 3 or 4 , characterized in that the temperature change rate threshold is 1-5°C/s. When at least two of the battery voltage change value, battery temperature, battery temperature change rate, and battery expansion force change value exceed respective predetermined values, it is determined that thermal runaway has occurred in the power battery. a power battery thermal runaway level identification module configured to determine and then identify a power battery thermal runaway level based on the type of condition exceeding a predetermined value;
a thermal runaway pre-alarm module for performing a power battery thermal runaway pre-alarm based on the power battery thermal runaway level;
A pre-warning device for thermal runaway of a power battery, characterized by comprising: at least one processor;
a memory communicatively coupled with the at least one processor;
including
the memory stores instructions executable by the at least one processor;
An electronic device characterized in that said instructions cause said at least one processor to perform the method of any of claims 1-5 and are executed by said at least one processor. A medium characterized in that it stores computer instructions for causing a computer to perform the method of any of claims 1-5 .

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