Power battery thermal runaway early warning method and system based on multiple physical fields

Abstract

The invention relates to the technical field of environmental bin power battery thermal runaway early warning, and discloses a power battery thermal runaway early warning method and system based on multiple physical fields, and the method comprises the steps: S1, collecting the smoke concentration, inflammable gas concentration and temperature of different positions in an environment; s2, respectively converting the collected smoke concentration, flammable gas and temperature into standard values; s3, calculating a smoke concentration predicted value, an inflammable gas concentration predicted value, a temperature predicted value and a temperature rise rate predicted value by using the smoke concentration standard value, the inflammable gas concentration standard value and the temperature standard value respectively; s4, determining an early warning level and the like according to the smoke concentration predicted value, the inflammable gas concentration predicted value, the temperature predicted value and the temperature rise rate predicted value by utilizing an early warning judgment rule; according to the power battery thermal runaway early warning method and system based on the multi-physical field, the power battery thermal runaway risk can be effectively reduced, and personnel safety and equipment safety in places such as an environment bin and a laboratory are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of early warning technology for thermal runaway of power batteries in environmental storage, and specifically to a method and system for early warning of thermal runaway of power batteries based on multiphysics. Background Technology

[0002] As the performance indicators of automotive power systems continue to improve and the level of electrification increases, the safety of power batteries, as a crucial component, is becoming increasingly prominent. Currently, power batteries, especially lithium batteries, pose a risk of thermal runaway. When a power battery experiences thermal runaway, it releases a large amount of heat (>800℃), igniting the electrolyte and surrounding materials, triggering a chain reaction that can lead to explosions and fires. Simultaneously, it releases toxic and harmful gases such as HF and CO, causing poisoning to personnel and environmental pollution. Existing safety measures for power battery environmental enclosures mainly focus on the following aspects: (1) Ventilation and cooling: Under normal circumstances, proper ventilation is sufficient to meet the requirements for safe storage and general testing of power batteries, but the ventilation system may not be sufficient for the treatment of toxic gases.

[0003] (2) Fire warning: Establish a power battery fire warning system based on multiple dimensions such as smoke, temperature and concentration of harmful gases. However, traditional warning systems have problems such as false alarms and slow response speed. They lack accurate prediction of the thermal runaway development of power batteries, and the warning is often issued at the same time as the fire has already occurred.

[0004] (3) Fire isolation: The power battery is placed separately and fire-fighting facilities such as high-pressure fine water mist and fire extinguishers are prepared. However, the existing environmental chamber's fire-fighting and early warning functions are not perfect and it is necessary to rely on the environmental chamber's infrastructure. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method and system for early warning of thermal runaway in power batteries based on multiphysics fields. This method and system are used for early warning of thermal runaway in walk-in power battery environmental chambers, effectively solving the problems of thermal runaway in power batteries and the safety issues it causes. Specifically, the technical problems solved include: (1) Accurate and rapid early warning: Build a fire early warning model based on multiple physical fields such as temperature, temperature gradient, smoke, and harmful gases to achieve accurate and rapid early warning of thermal runaway fires of power batteries.

[0006] (2) High-efficiency fire isolation: The water circuit is controlled by electromagnetic valves, and equipped with two water circuits: a high-flow water injector and a high-pressure spray cooling device, to quickly control the spread of fire that may be caused by thermal runaway.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A multiphysics-based early warning method for thermal runaway of power batteries includes: S1, collecting smoke concentration, flammable gas concentration, and temperature at different locations in the environment; S2, converting the collected smoke concentration, flammable gas concentration, and temperature into standard values; S3, calculating predicted values ​​for smoke concentration, flammable gas concentration, temperature, and temperature rise rate using the standard values ​​for smoke concentration, flammable gas concentration, and temperature; S4, determining the early warning level based on the predicted values ​​for smoke concentration, flammable gas concentration, temperature, and temperature rise rate using early warning judgment rules; and S5, implementing early warning measures according to the early warning level. The early warning levels include Level 1 early warning, Level 2 early warning, and Level 2 early warning. The warning system is divided into three levels: Level 1 and Level 2. The warning determination rules include: if the predicted smoke concentration reaches the smoke concentration threshold and / or the predicted flammable gas concentration reaches the flammable gas concentration threshold, or the predicted temperature reaches the temperature threshold, it is identified as a Level 1 warning; if the predicted smoke concentration reaches the smoke concentration threshold or the predicted flammable gas concentration reaches the flammable gas concentration threshold, and the predicted temperature also reaches the temperature threshold, it is identified as a Level 2 warning; if the predicted smoke concentration reaches the smoke concentration threshold, the predicted flammable gas concentration reaches the flammable gas concentration threshold, the predicted temperature reaches the temperature threshold, and the predicted temperature rise rate reaches the temperature rise rate threshold, it is identified as a Level 3 warning.

[0008] In this invention, preferably, the predicted smoke concentration is calculated using a standard value of smoke concentration, and the prediction model used is as follows: In the formula, C(t) is the predicted smoke concentration, and C0 is the standard smoke concentration. The turbulent entrainment aversion intensity coefficient is... The turbulence attenuation coefficient is... λ is the angular frequency of turbulent eddy shedding, λ is the smoke concentration growth rate constant, and t is time.

[0009] In this invention, preferably, the predicted value of flammable gas concentration is calculated using the standard value of flammable gas concentration, and the prediction model used is as follows: In the formula, G(t) is the predicted value of flammable gas concentration, and G0 is the standard value of flammable gas concentration. Let be the saturation rate of gas release, k be the rate of increase in flammable gas concentration, and t be time.

[0010] In this invention, preferably, the predicted temperature value and the predicted temperature rise rate are calculated using a standard temperature value, and the prediction model used is as follows: ΔT = dT / dt = α + 2βt In the formula, T(t) is the predicted temperature value, ΔT is the predicted temperature rise rate, and T0 is the standard temperature value. 'This is the thermal relaxation time.' This represents the amplitude of temperature oscillation. The system start / stop frequency. The strength coefficient of the thermal hysteresis model is... T0 is the reciprocal of the thermal relaxation time, T0 is the initial temperature, and α and β are both temperature change coefficients.

[0011] In this invention, preferably, step S2 involves converting the collected smoke concentration, flammable gas, and temperature into standard values. The conversion rule is as follows: calculate the average value of all original collected values, compare the average value with the maximum value of all original collected values, and if the number of maximum values ​​greater than the average value exceeds 10% of the average value, then the average value is used as the standard value; if the number of maximum values ​​greater than the average value does not exceed 10% of the average value, then the maximum value is used as the standard value.

[0012] In this invention, preferably, step S5 includes: S51, if the warning level is Level 1, an alarm signal is issued, the exhaust ventilation is turned on, and the cooling capacity is increased; S52, if the warning level is Level 2, an enhanced alarm signal is issued, the fire extinguishing device is prepared to be activated, the main relay is turned off, the compartment door is closed, the heptafluoropropane fire extinguisher is turned on, and the battery coolant flow rate is increased; S53, if the warning level is Level 3, the fire extinguishing device is activated, the ventilation system is turned off, and the water pipe solenoid valve is turned on; S54, if the water level is detected to have reached the water level threshold, a water level alarm is issued, and the water pipe solenoid valve is turned off.

[0013] In this invention, preferably, the smoke concentration threshold is 10 ppm, the flammable gas concentration threshold is 50 ppm, the temperature threshold is 60°C, and the liquid level threshold is 50 mm.

[0014] A multiphysics-based power battery thermal runaway early warning system includes: a data acquisition module for acquiring smoke concentration, flammable gas concentration, and temperature at different locations in the environment; a standardization module for converting the acquired smoke concentration, flammable gas concentration, and temperature into standard values; a prediction module for calculating predicted values ​​for smoke concentration, flammable gas concentration, temperature, and temperature rise rate using the standard values ​​for smoke concentration, flammable gas concentration, and temperature; a judgment module for determining the early warning level based on the predicted values ​​for smoke concentration, flammable gas concentration, temperature, and temperature rise rate using early warning judgment rules; and an early warning execution module for executing early warning measures according to the early warning level. The warnings are categorized into Level 1, Level 2, and Level 3. The warning determination rules include: Level 1 warning if the predicted smoke concentration reaches the smoke concentration threshold and / or the predicted flammable gas concentration reaches the flammable gas concentration threshold, or the predicted temperature reaches the temperature threshold; Level 2 warning if the predicted smoke concentration reaches the smoke concentration threshold or the predicted flammable gas concentration reaches the flammable gas concentration threshold, and the predicted temperature also reaches the temperature threshold; and Level 3 warning if the predicted smoke concentration reaches the smoke concentration threshold, the predicted flammable gas concentration reaches the flammable gas concentration threshold, the predicted temperature reaches the temperature threshold, and the predicted temperature rise rate reaches the temperature rise rate threshold.

[0015] In this invention, preferably, the predicted smoke concentration is calculated using a standard value of smoke concentration, and the prediction model used is as follows: In the formula, C(t) is the predicted smoke concentration, and C0 is the standard smoke concentration. The turbulent entrainment aversion intensity coefficient is... The turbulence attenuation coefficient is... λ is the turbulent eddy shedding angular frequency, λ is the smoke concentration growth rate constant, and t is time; The predicted value of flammable gas concentration is calculated using the standard value of flammable gas concentration. The prediction model used is as follows: In the formula, G(t) is the predicted value of flammable gas concentration, and G0 is the standard value of flammable gas concentration. denoted as the saturation rate of gas release, k is the rate of increase in flammable gas concentration, and t is time; The predicted temperature and temperature rise rate are calculated using standard temperature values. The prediction model used is as follows: ΔT = dT / dt = α + 2βt In the formula, T(t) is the predicted temperature value, and ΔT is the predicted temperature rise rate. This is the standard temperature value. For thermal relaxation time, This represents the amplitude of temperature oscillation. The system start / stop frequency. The strength coefficient of the thermal hysteresis model is... The thermal relaxation time is the reciprocal of T0, where T0 is the initial temperature and α and β are temperature variation coefficients. The collected smoke concentration, flammable gas concentration, and temperature are converted into standard values ​​respectively. The conversion rules are as follows: the average value of all original collected values ​​is calculated, and the average value is compared with the maximum value of all original collected values. If the number of maximum values ​​greater than the average value exceeds 10% of the average value, the average value is used as the standard value; if the number of maximum values ​​greater than the average value does not exceed 10% of the average value, the maximum value is used as the standard value. The threshold values ​​for smoke concentration are 10 ppm, flammable gas concentration are 50 ppm, and temperature are 60℃.

[0016] In this invention, preferably, the early warning execution module includes: a primary early warning execution unit, used to issue an alarm signal, open the exhaust ventilation, and increase the cooling capacity if the early warning level is primary; a secondary early warning execution unit, used to issue an enhanced alarm signal, prepare to activate the fire extinguishing device, close the main relay, close the compartment door, open the heptafluoropropane fire extinguisher, and increase the battery coolant flow if the early warning level is secondary; a tertiary early warning execution unit, used to activate the fire extinguishing device, close the ventilation system, and open the water pipe solenoid valve if the early warning level is tertiary; and a liquid level early warning execution unit, used to detect... When the water level reaches the water level threshold, a water level alarm is issued and the water pipe solenoid valve is closed. The water level warning execution unit includes a water level sensor for detecting the water level height, and the water level threshold is set to 50mm. The acquisition module includes: at least 6 temperature sensors, of which 4 are arranged on the surface of the battery module, 1 is arranged on the top of the environmental chamber, and 1 is arranged at the exhaust vent; at least 2 smoke sensors, located at the top and bottom of the environmental chamber respectively; and at least 3 flammable gas sensors, of which 1 is arranged near the battery pressure relief valve and 2 are located in the corners of the environmental chamber, distributed diagonally.

[0017] Compared with the prior art, the beneficial effects of the present invention are: (1) Reduce safety risks: It provides a multi-functional power battery safety control system, which can effectively reduce the risk of thermal runaway of power batteries, ensure the safety of personnel and equipment in places such as environmental warehouses and laboratories, and reduce casualties and property losses caused by power battery fires.

[0018] (2) Improve the accuracy and response speed of early warning: It realizes accurate and rapid early warning of thermal runaway fire of power battery. Compared with traditional early warning system, it has higher accuracy and faster response speed, and can detect hidden dangers in the early stage of fire, prevent them from happening in advance, and buy valuable time for fire extinguishing measures.

[0019] (3) Enhance fire extinguishing effect and isolation capability: Through efficient fire isolation measures, minimize the possibility of fire spread, reduce fire losses, improve the safety and reliability of power batteries during use, ensure that fire can be controlled and extinguished in the first time, and avoid the fire from spreading and causing greater damage to surrounding equipment and environment. Attached Figure Description

[0020] Figure 1 This is a flowchart of a method for early warning of thermal runaway of power battery based on multiphysics field according to an embodiment of the present invention.

[0021] Figure 2 This is a flowchart of another embodiment of the present invention: a power battery thermal runaway early warning method based on multiphysics fields.

[0022] Figure 3 This is a schematic diagram of the structure of a power battery thermal runaway early warning system based on multiphysics field according to another embodiment of the present invention.

[0023] Figure 4 This is a schematic diagram of the structure of the early warning execution module in a power battery thermal runaway early warning system based on multiphysics field, according to another embodiment of the present invention.

[0024] In the attached diagram: 1. Data Acquisition Module; 2. Standardization Module; 3. Prediction Module; 4. Judgment Module; 5. Early Warning Execution Module; 51. First-Level Early Warning Execution Unit; 52. Second-Level Early Warning Execution Unit; 53. Third-Level Early Warning Execution Unit; 54. Liquid Level Early Warning Execution Unit. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set to" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] Please see Figure 1 A preferred embodiment of the present invention provides a method for early warning of thermal runaway of power batteries based on multiphysics, comprising: S1 collects smoke concentration, flammable gas concentration and temperature at different locations in the environment.

[0029] Smoke sensors, flammable gas sensors, and temperature sensors are deployed in environments such as environmental chambers and laboratories to collect data on smoke concentration, flammable gas concentration, and temperature. There are more than two of each type of sensor, which are placed in different locations in the environment to obtain more comprehensive and accurate data on smoke concentration, flammable gas concentration, and temperature.

[0030] In this embodiment, preferably, the sensor group uses 6 temperature sensors (response speed of 10ms, accuracy of ±0.5℃), of which 4 are arranged on the surface of the battery module, 1 is arranged on the top of the environmental chamber, and 1 is arranged at the exhaust vent; 2 smoke sensors (photoelectric type, range 0-1000ppm), located at the top and bottom of the chamber respectively; 3 flammable gas sensors (catalytic combustion type, detecting HF, THC, CO, etc., range 0-100ppm), one near the battery pressure relief valve and two located in the corners of the chamber (diagonally distributed); and one water level sensor, using a float type, installed in the drainage trough at the bottom of the chamber, to detect whether the water level has reached the upper limit (trigger value 50mm).

[0031] S2 converts the collected smoke concentration, flammable gas and temperature into standard values ​​respectively.

[0032] Since there are more than two smoke sensors, flammable gas sensors, and temperature sensors, the data obtained cannot be directly used for early warning calculations. It is necessary to fuse the data collected by similar sensors and use the fused data as a standard value for subsequent early warning calculations.

[0033] Preferably, the collected smoke concentration, flammable gas, and temperature are converted into standard values ​​respectively. The conversion rule is as follows: calculate the average of all original collected values, and compare the average with the maximum value of all original collected values. If the number of maximum values ​​greater than the average exceeds 10% of the average, the average is used as the standard value; if the number of maximum values ​​greater than the average does not exceed 10% of the average, the maximum value is used as the standard value. For example, calculate the average temperature value from the temperature values ​​collected by six temperature sensors, and then compare the maximum temperature value among the six temperature sensors with the average temperature value. If the difference between the two is greater than 10% of the average temperature value, the maximum temperature value is considered an anomaly and is not used; instead, the average temperature value is used as the temperature standard value. If the difference is no greater than 10% of the average, the maximum temperature value is considered normal and is used as the temperature standard value, thus maximizing the warning effect.

[0034] S3 calculates the predicted values ​​of smoke concentration, flammable gas concentration, temperature, and temperature rise rate using the standard values ​​of smoke concentration, flammable gas concentration, and temperature, respectively.

[0035] By using predictive models and standard values, it is possible to predict changes in smoke concentration, flammable gas concentration, and temperature in the environmental chamber over a certain period of time, thereby enabling early detection and warning of potential thermal runaway of the power battery.

[0036] Preferably, the predicted smoke concentration is calculated using the standard value of smoke concentration, and the prediction model used is as follows: In the formula, the integral term represents the randomness of simulated turbulent diffusion, C(t) is the predicted smoke concentration in ppm, and C0 is the initial smoke concentration (standard smoke concentration in ppm). is the turbulent entrainment aversion intensity coefficient, with units of ppm / s; This is the turbulence attenuation coefficient, in seconds. -1 ; λ is the angular frequency of turbulent eddy shedding, in rad / s; λ is the smoke concentration growth rate constant, and t is time; C th The smoke concentration threshold is set to 10 ppm, when C(t) ≥ C th When the predicted smoke concentration reaches the smoke concentration threshold, a smoke data warning is triggered.

[0037] Preferably, the predicted value of flammable gas concentration is calculated using the standard value of flammable gas concentration, and the prediction model used is as follows: In the formula, G(t) is the predicted value of flammable gas concentration in ppm; G0 is the initial flammable gas concentration (standard value of flammable gas concentration) in ppm. The gas release saturation rate is expressed in seconds. -1 ; k is the rate of increase in flammable gas concentration, in ppm / s; t is time. G th The flammable gas concentration threshold is set at 50 ppm, when G ≥ G th When the predicted flammable gas concentration reaches the flammable gas concentration threshold, a flammable gas data warning is triggered.

[0038] Preferably, the predicted temperature and predicted rate of temperature rise are calculated using standard temperature values, and the prediction model used is as follows: ΔT = dT / dt = α + 2βt In the formula, the integral term represents the thermal hysteresis model, describing the delayed effect of heat transfer. T(t) is the predicted temperature value in °C; ΔT is the predicted rate of temperature rise in °C / s; and T0 is the initial temperature (standard temperature value) in °C. 'This is the thermal relaxation time.' This represents the temperature oscillation amplitude, expressed in °C. This is the system start / stop angular frequency, in rad / s; The strength coefficient of the thermal hysteresis model is... This is the reciprocal of the thermal relaxation time, in seconds. -1 T0 is the initial temperature, and α and β are temperature change coefficients, which are generally obtained by fitting experimental data. th Temperature thresholds are set to 60℃ and 70℃; ΔT th The temperature rise rate threshold is set to 5℃ / s, when T≥T th ΔT≥ΔT th When the predicted temperature value reaches the temperature threshold or the predicted temperature rise rate reaches the temperature rise rate threshold, a temperature data warning is triggered.

[0039] S4. The warning level is determined by using the warning judgment rules to determine the warning level based on the predicted values ​​of smoke concentration, flammable gas concentration, temperature, and temperature rise rate.

[0040] Specifically, the warning levels include Level 1, Level 2, and Level 3. The rules for determining the warning level include: (1) If the predicted smoke concentration reaches the smoke concentration threshold and / or the predicted flammable gas concentration reaches the flammable gas concentration threshold, or the predicted temperature reaches the temperature threshold, it shall be identified as a Level I warning. (2) If the predicted smoke concentration reaches the smoke concentration threshold or the predicted flammable gas concentration reaches the flammable gas concentration threshold, and the predicted temperature reaches the temperature threshold at the same time, it is identified as a level II warning. (3) If the predicted smoke concentration reaches the smoke concentration threshold, the predicted flammable gas concentration reaches the flammable gas concentration threshold, the predicted temperature reaches the temperature threshold, and the predicted temperature rise rate reaches the temperature rise rate threshold at the same time, it is considered as a Level III warning.

[0041] Preferably, the smoke concentration threshold is 10 ppm, the flammable gas concentration threshold is 50 ppm, and the temperature threshold is 60°C.

[0042] S5, implement warning measures according to the warning level.

[0043] Specifically, such as Figure 2 As shown, S5 includes: S51: If the warning level is Level 1, an alarm signal will be issued, the exhaust ventilation will be turned on, and the cooling capacity will be increased.

[0044] If a Level 1 warning is triggered, the system will issue an alarm signal to remind staff to pay attention to the situation inside the environmental chamber and take preventive measures such as turning on the exhaust ventilation and increasing the cooling capacity.

[0045] S52, if the warning level is Level II, then issue an enhanced alarm signal, prepare to activate the fire extinguishing device, shut down the main relay, close the compartment door, activate the heptafluoropropane fire extinguisher, and increase the battery coolant flow.

[0046] Upon triggering a Level 2 warning, the system will further amplify the alarm signal and notify the central control unit to prepare to activate the fire suppression system. Response measures will include shutting down the main relay, closing the compartment door, activating the heptafluoropropane fire extinguisher, and increasing the battery coolant flow rate.

[0047] S53, if the warning level is level three, then activate the fire extinguishing device, shut off the ventilation system, and open the water pipe solenoid valve.

[0048] When a Level 3 warning is triggered, it indicates that there are obvious signs of fire within the environmental chamber. The system will immediately activate the fire extinguishing devices and simultaneously shut down the ventilation system of the environmental chamber to prevent the fire from spreading. Appropriate measures will be taken, such as opening the water pipe solenoid valve.

[0049] S54: If the water level is detected to have reached the water level threshold, a water level alarm will be issued and the water pipe solenoid valve will be closed.

[0050] When the water level sensor detects that the water level has reached the upper limit, it will also sound an alarm, and at this time, response measures such as shutting off the water pipe solenoid valve will be taken.

[0051] Preferably, the liquid level threshold is set to 50mm. The water level sensor can be a float type, installed in the drainage trough at the bottom of the tank, to detect whether the water level has reached the upper limit (liquid level threshold).

[0052] like Figure 3 As shown, another embodiment of the present invention also provides a power battery thermal runaway early warning system based on multiphysics, comprising: The data acquisition module 1 is used to collect smoke concentration, flammable gas concentration and temperature at different locations in the environment.

[0053] Specifically, the acquisition module 1 includes: at least 6 temperature sensors, of which 4 are arranged on the surface of the battery module, 1 is arranged on the top of the environmental chamber, and 1 is arranged at the exhaust vent; at least 2 smoke sensors, located at the top and bottom of the environmental chamber respectively; and at least 3 flammable gas sensors, of which 1 is arranged near the battery pressure relief valve and 2 are located in the corners of the environmental chamber, distributed diagonally.

[0054] Standardization module 2 is used to convert the collected smoke concentration, flammable gas and temperature into standard values ​​respectively.

[0055] Prediction module 3 is used to calculate predicted values ​​for smoke concentration, flammable gas concentration, temperature, and temperature rise rate using standard values ​​for smoke concentration, flammable gas concentration, and temperature, respectively.

[0056] The judgment module 4 is used to determine the warning level by using the warning judgment rules to predict the smoke concentration, flammable gas concentration, temperature and temperature rise rate.

[0057] The early warning execution module 5 is used to execute early warning measures according to the early warning level.

[0058] Specifically, such as Figure 4 As shown, the early warning execution module 5 includes: The first-level early warning execution unit 51 is used to issue an alarm signal, turn on the exhaust ventilation, and increase the cooling capacity if the early warning level is first-level. The secondary warning execution unit 52 is used to issue an enhanced alarm signal, prepare to activate the fire extinguishing device, shut down the main relay, close the compartment door, open the heptafluoropropane fire extinguisher, and increase the battery coolant flow if the warning level is secondary warning. The Level 3 Early Warning Execution Unit 53 is used to activate the fire extinguishing device, shut down the ventilation system, and open the water pipe solenoid valve if the early warning level is Level 3. The liquid level warning execution unit 54 is used to issue a liquid level alarm and close the water pipe solenoid valve if the water level is detected to have reached the upper limit.

[0059] The liquid level warning execution unit 54 includes a water level sensor for detecting the water level height, and the liquid level threshold is set to 50 mm.

[0060] The warning levels include Level 1, Level 2, and Level 3.

[0061] The rules for determining early warning include: If the predicted smoke concentration reaches the smoke concentration threshold and / or the predicted flammable gas concentration reaches the flammable gas concentration threshold, or the predicted temperature reaches the temperature threshold, it is considered a Level 1 warning. If the predicted smoke concentration reaches the smoke concentration threshold or the predicted flammable gas concentration reaches the flammable gas concentration threshold, and the predicted temperature also reaches the temperature threshold, then it is considered a Level II warning. If the predicted smoke concentration reaches the smoke concentration threshold, the predicted flammable gas concentration reaches the flammable gas concentration threshold, the predicted temperature reaches the temperature threshold, and the predicted temperature rise rate reaches the temperature rise rate threshold simultaneously, then it is considered a Level III warning.

[0062] The predicted smoke concentration is calculated using the standard value of smoke concentration. The prediction model used is as follows: In the formula, C(t) is the predicted smoke concentration, and C0 is the standard smoke concentration. The turbulent entrainment aversion intensity coefficient is... The turbulence attenuation coefficient is... λ is the angular frequency of turbulent eddy shedding, λ is the smoke concentration growth rate constant, and t is time.

[0063] The predicted value of flammable gas concentration is calculated using the standard value of flammable gas concentration. The prediction model used is as follows: In the formula, G(t) is the predicted value of flammable gas concentration, and G0 is the standard value of flammable gas concentration. Let be the saturation rate of gas release, k be the rate of increase in flammable gas concentration, and t be time.

[0064] The predicted temperature and temperature rise rate are calculated using standard temperature values. The prediction model used is as follows: ΔT = dT / dt = α + 2βt In the formula, T(t) is the predicted temperature value, and ΔT is the predicted temperature rise rate. This is the standard temperature value. For thermal relaxation time, This represents the amplitude of temperature oscillation. The system start / stop frequency. The strength coefficient of the thermal hysteresis model is... T0 is the reciprocal of the thermal relaxation time, T0 is the initial temperature, and α and β are temperature variation coefficients.

[0065] The collected smoke concentration, flammable gas and temperature were converted into standard values ​​respectively. The conversion rules are as follows: calculate the average value of all original collected values, and compare the average value with the maximum value of all original collected values. If the number of maximum values ​​greater than the average value exceeds 10% of the average value, then the average value is used as the standard value; if the number of maximum values ​​greater than the average value does not exceed 10% of the average value, then the maximum value is used as the standard value.

[0066] The threshold for smoke concentration is 10 ppm, the threshold for flammable gas concentration is 50 ppm, and the threshold for temperature is 60℃.

[0067] The multi-physics-based early warning method and system for thermal runaway of power batteries of this invention achieves accurate and rapid early warning of thermal runaway fires of power batteries in environmental storage compartments. Compared with traditional early warning systems, it has higher accuracy and faster response speed. By comprehensively utilizing multi-physics information such as temperature, smoke, and flammable gases, it can detect potential hazards in the early stages of a fire, preventing them from escalating and buying time for firefighting measures.

[0068] The above description is a detailed description of the preferred embodiments of the present invention. However, the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modifications made under the technical spirit of the present invention should fall within the patent scope covered by the present invention.

Claims

1. A method for early warning of thermal runaway in power batteries based on multiphysics, characterized in that, include: S1, collect smoke concentration, flammable gas concentration and temperature at different locations in the environment; S2 converts the collected smoke concentration, flammable gas and temperature into standard values ​​respectively; S3, calculate the predicted values ​​of smoke concentration, flammable gas concentration, temperature and temperature rise rate using the standard values ​​of smoke concentration, flammable gas concentration and temperature respectively. S4. The warning level is determined by using the warning judgment rules to determine the warning level based on the predicted values ​​of smoke concentration, flammable gas concentration, temperature, and temperature rise rate. S5, Implement warning measures according to the warning level; The warning levels include Level 1, Level 2, and Level 3. The early warning determination rules include: If the predicted smoke concentration reaches the smoke concentration threshold and / or the predicted flammable gas concentration reaches the flammable gas concentration threshold, or the predicted temperature reaches the temperature threshold, it is considered a Level 1 warning. If the predicted smoke concentration reaches the smoke concentration threshold or the predicted flammable gas concentration reaches the flammable gas concentration threshold, and the predicted temperature also reaches the temperature threshold, then it is considered a Level II warning. If the predicted smoke concentration reaches the smoke concentration threshold, the predicted flammable gas concentration reaches the flammable gas concentration threshold, the predicted temperature reaches the temperature threshold, and the predicted temperature rise rate reaches the temperature rise rate threshold simultaneously, then it is considered a Level III warning.

2. The method for early warning of thermal runaway of power batteries based on multiphysics fields according to claim 1, characterized in that, The predicted smoke concentration is calculated using the standard value of smoke concentration. The prediction model used is as follows: In the formula, C(t) is the predicted smoke concentration, and C0 is the standard smoke concentration. The turbulent entrainment aversion intensity coefficient is... The turbulence attenuation coefficient is... λ is the angular frequency of turbulent eddy shedding, λ is the smoke concentration growth rate constant, and t is time.

3. The method for early warning of thermal runaway of power batteries based on multiphysics fields according to claim 1, characterized in that, The predicted value of flammable gas concentration is calculated using the standard value of flammable gas concentration. The prediction model used is as follows: In the formula, G(t) is the predicted value of flammable gas concentration, and G0 is the standard value of flammable gas concentration. Let be the saturation rate of gas release, k be the rate of increase in flammable gas concentration, and t be time.

4. The method for early warning of thermal runaway of power batteries based on multiphysics fields according to claim 1, characterized in that, The predicted temperature and temperature rise rate are calculated using standard temperature values. The prediction model used is as follows: ,ΔT=dT / dt=α+2βt In the formula, T(t) is the predicted temperature value, ΔT is the predicted temperature rise rate, and T0 is the standard temperature value. 'This is the thermal relaxation time.' This represents the amplitude of temperature oscillation. The system start / stop frequency. The strength coefficient of the thermal hysteresis model is... T0 is the reciprocal of the thermal relaxation time, T0 is the initial temperature, and α and β are both temperature change coefficients.

5. The method for early warning of thermal runaway of power batteries based on multiphysics fields according to claim 1, characterized in that, S2 describes converting the collected smoke concentration, flammable gas, and temperature into standard values. The conversion rule is as follows: calculate the average of all original collected values, compare the average with the maximum value of all original collected values. If the number of maximum values ​​greater than the average exceeds 10% of the average, then the average is used as the standard value; if the number of maximum values ​​greater than the average does not exceed 10% of the average, then the maximum value is used as the standard value.

6. The method for early warning of thermal runaway of power batteries based on multiphysics fields according to claim 1, characterized in that, S5 includes: S51, if the warning level is Level 1, an alarm signal will be issued, the exhaust ventilation will be turned on, and the cooling capacity will be increased; S52, if the warning level is Level II, then issue an enhanced alarm signal, prepare to activate the fire extinguishing device, shut down the main relay, close the compartment door, open the heptafluoropropane fire extinguisher, and increase the battery coolant flow rate; S53, if the warning level is Level III, then activate the fire extinguishing device, shut down the ventilation system, and open the water pipe solenoid valve; S54 If the water level is detected to have reached the water level threshold, a water level alarm will be issued and the water pipe solenoid valve will be closed.

7. The method for early warning of thermal runaway of power batteries based on multiphysics fields according to claim 6, characterized in that, The smoke concentration threshold is 10 ppm, the flammable gas concentration threshold is 50 ppm, the temperature threshold is 60°C, and the liquid level threshold is 50 mm.

8. A power battery thermal runaway early warning system based on multiphysics, characterized in that, include: The data acquisition module is used to collect smoke concentration, flammable gas concentration, and temperature at different locations in the environment. The standardization module is used to convert the collected smoke concentration, flammable gas and temperature into standard values ​​respectively; The prediction module is used to calculate the predicted values ​​of smoke concentration, flammable gas concentration, temperature, and temperature rise rate using the standard values ​​of smoke concentration, flammable gas concentration, and temperature, respectively. The judgment module is used to determine the warning level by using the warning judgment rules to predict the smoke concentration, flammable gas concentration, temperature, and temperature rise rate. The early warning execution module is used to execute early warning measures according to the early warning level; The warning levels include Level 1, Level 2, and Level 3. The early warning determination rules include: If the predicted smoke concentration reaches the smoke concentration threshold and / or the predicted flammable gas concentration reaches the flammable gas concentration threshold, or the predicted temperature reaches the temperature threshold, it is considered a Level 1 warning. If the predicted smoke concentration reaches the smoke concentration threshold or the predicted flammable gas concentration reaches the flammable gas concentration threshold, and the predicted temperature also reaches the temperature threshold, then it is considered a Level II warning. If the predicted smoke concentration reaches the smoke concentration threshold, the predicted flammable gas concentration reaches the flammable gas concentration threshold, the predicted temperature reaches the temperature threshold, and the predicted temperature rise rate reaches the temperature rise rate threshold simultaneously, then it is considered a Level III warning.

9. The power battery thermal runaway early warning system based on multiphysics fields according to claim 8, characterized in that, The predicted smoke concentration is calculated using the standard value of smoke concentration. The prediction model used is as follows: In the formula, C(t) is the predicted smoke concentration, and C0 is the standard smoke concentration. The turbulent entrainment aversion intensity coefficient is... The turbulence attenuation coefficient is... λ is the turbulent eddy shedding angular frequency, λ is the smoke concentration growth rate constant, and t is time; The predicted value of flammable gas concentration is calculated using the standard value of flammable gas concentration. The prediction model used is as follows: In the formula, G(t) is the predicted value of flammable gas concentration, and G0 is the standard value of flammable gas concentration. denoted as the saturation rate of gas release, k is the rate of increase in flammable gas concentration, and t is time; The predicted temperature and temperature rise rate are calculated using standard temperature values. The prediction model used is as follows: ,ΔT=dT / dt=α+2βt In the formula, T(t) is the predicted temperature value, and ΔT is the predicted temperature rise rate. This is the standard temperature value. For thermal relaxation time, This represents the amplitude of temperature oscillation. The system start / stop frequency. The strength coefficient of the thermal hysteresis model is... The thermal relaxation time is the reciprocal of T0, where T0 is the initial temperature and α and β are temperature variation coefficients. The collected smoke concentration, flammable gas, and temperature were converted into standard values ​​respectively. The conversion rules were as follows: the average value of all original collected values ​​was calculated, and the average value was compared with the maximum value of all original collected values. If the number of maximum values ​​greater than the average value exceeded 10% of the average value, the average value was used as the standard value; if the number of maximum values ​​greater than the average value did not exceed 10% of the average value, the maximum value was used as the standard value. The smoke concentration threshold is 10 ppm, the flammable gas concentration threshold is 50 ppm, and the temperature threshold is 60°C.

10. The power battery thermal runaway early warning system based on multiphysics fields according to claim 8, characterized in that, The early warning execution module includes: The Level 1 Early Warning Execution Unit is used to issue an alarm signal, activate the exhaust ventilation, and increase the cooling capacity if the early warning level is Level 1. The Level 2 Early Warning Execution Unit is used to issue an enhanced alarm signal, prepare to activate the fire extinguishing device, shut down the main relay, close the compartment door, open the heptafluoropropane fire extinguisher, and increase the battery coolant flow if the early warning level is Level 2. The Level 3 Early Warning Execution Unit is used to activate the fire extinguishing device, shut down the ventilation system, and open the water pipe solenoid valve if the early warning level is Level 3. The liquid level warning execution unit is used to issue a liquid level alarm and close the water pipe solenoid valve if the water level is detected to have reached the liquid level threshold. The liquid level early warning execution unit includes a water level sensor for detecting the water level height, and the liquid level threshold is set to 50mm. The acquisition module includes: There are at least 6 temperature sensors, 4 of which are arranged on the surface of the battery module, 1 on the top of the environmental chamber, and 1 at the exhaust vent. At least two smoke sensors are located at the top and bottom of the environmental chamber, respectively; At least three flammable gas sensors are provided, one of which is located near the battery pressure relief valve and two are located in the corners of the environmental chamber, distributed diagonally.

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