Method and system for early warning of thermal runaway of power battery based on multiple physical fields

Abstract

The present application relates to the technical field of environmental warehouse power battery thermal runaway early warning, and discloses a power battery thermal runaway early warning method and system based on multiple physical fields, comprising: S1, collecting smoke concentration, flammable gas concentration and temperature at different positions in the environment; S2, converting the collected smoke concentration, flammable gas and temperature into standard values respectively; S3, calculating smoke concentration prediction value, flammable gas concentration prediction value, temperature prediction value and temperature rise rate prediction value by using smoke concentration standard value, flammable gas concentration standard value and temperature standard value respectively; S4, determining early warning levels and the like by using early warning determination rules through smoke concentration prediction value, flammable gas concentration prediction value, temperature prediction value and temperature rise rate prediction value; the power battery thermal runaway early warning method and system based on multiple physical fields can effectively reduce the risk of power battery thermal runaway, and protect the safety of personnel and equipment in places such as environmental warehouses and laboratories.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environmental warehouse power battery thermal runaway early warning, in particular to a power battery thermal runaway early warning method and system based on multiple physical fields. BACKGROUND

[0002] With the continuous improvement of performance indicators of vehicle power systems and the continuous improvement of electrification, the safety problem of power batteries as a key link is increasingly prominent. Current power batteries, especially lithium batteries, have a risk of thermal runaway. When the power battery thermal runaway occurs, a large amount of heat (> 800℃) will be released, igniting the electrolyte and surrounding materials, triggering a chain reaction, leading to explosion and fire; at the same time, the release of HF, CO and other toxic and harmful gases will cause poisoning and environmental pollution. The existing safety measures for power battery environmental warehouse mainly focus on the following aspects:

[0003] (1) Ventilation cooling: Generally, good ventilation can meet the safety storage and general test requirements of power batteries, but the ventilation system may not meet the toxic gas treatment.

[0004] (2) Fire warning: Establish a multi-dimensional power battery fire warning system based on smoke, temperature and harmful gas concentration, but the traditional warning system has problems such as false alarm and slow response speed, lacks accurate prediction of the development of power battery thermal runaway, and the warning is often issued at the same time as the fire occurs.

[0005] (3) Fire isolation: Place the power battery separately, and prepare high-pressure water mist, fire extinguisher and other fire-fighting facilities, but the existing environmental warehouse fire-fighting and warning functions are not perfect and need to rely on the environmental warehouse infrastructure. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a power battery thermal runaway early warning method and system based on multiple physical fields, which is used for thermal runaway early warning of a walk-in power battery environmental warehouse, and effectively solves the safety problems caused by power battery thermal runaway. The technical problems to be solved include:

[0007] (1) Precise and rapid warning: build a fire warning model based on temperature, temperature gradient, smoke, harmful gas and other multiple physical fields to realize precise and rapid warning of power battery thermal runaway fire.

[0008] (2) Efficient fire isolation: use electromagnetic valves to control the opening and closing of the waterway, and equip two waterways with large-flow water injectors and high-pressure spray coolers to quickly control the fire spread caused by thermal runaway.

[0009] In order to achieve the above purpose, the present application provides the following technical solutions:

[0010] The power battery thermal runaway early warning method based on multiple physical fields comprises the following steps: S1, collecting smoke concentration, flammable gas concentration and temperature at different positions in the environment; S2, converting the collected smoke concentration, flammable gas concentration and temperature into standard values; S3, calculating smoke concentration prediction value, flammable gas concentration prediction value, temperature prediction value and temperature rise rate prediction value by using the smoke concentration standard value, flammable gas concentration standard value and temperature standard value respectively; S4, determining the early warning level by using the early warning judgment rule through the smoke concentration prediction value, flammable gas concentration prediction value, temperature prediction value and temperature rise rate prediction value; S5, executing early warning measures according to the early warning level; the early warning level comprises first-level early warning, second-level early warning and third-level early warning; the early warning judgment rule comprises: if the smoke concentration prediction value reaches the smoke concentration threshold value and / or the flammable gas concentration prediction value reaches the flammable gas concentration threshold value, or the temperature prediction value reaches the temperature threshold value, it is determined as the first-level early warning; if the smoke concentration prediction value reaches the smoke concentration threshold value or the flammable gas concentration prediction value reaches the flammable gas concentration threshold value, and at the same time, the temperature prediction value reaches the temperature threshold value, it is determined as the second-level early warning; if the smoke concentration prediction value reaches the smoke concentration threshold value, the flammable gas concentration prediction value reaches the flammable gas concentration threshold value, the temperature prediction value reaches the temperature threshold value and the temperature rise rate prediction value reaches the temperature rise rate threshold value at the same time, it is determined as the third-level early warning.

[0011] In the application, preferably, the smoke concentration prediction value is calculated by using the smoke concentration standard value, and the prediction model adopted is as follows:

[0012]

[0013] In the formula, C(t) is the smoke concentration prediction value, C0 is the smoke concentration standard value, is the turbulent flow entrainment intensity coefficient, is the turbulent flow decay coefficient, is the turbulent flow vortex shedding angular frequency, λ is the smoke concentration growth rate constant, and t is time.

[0014] In the application, preferably, the flammable gas concentration prediction value is calculated by using the flammable gas concentration standard value, and the prediction model adopted is as follows:

[0015]

[0016] In the formula, G(t) is the flammable gas concentration prediction value, G0 is the flammable gas concentration standard value, is the gas release saturation rate, k is the flammable gas concentration increase rate, and t is time.

[0017] In the application, preferably, the temperature prediction value and the temperature rise rate prediction value are calculated by using the temperature standard value, and the prediction model adopted is as follows:

[0018] , ΔT = dT / dt = α + 2βt

[0019] In the formula, T(t) is a temperature prediction value, ΔT is a temperature rise rate prediction value, T0 is a temperature standard value, is a thermal relaxation time, is a temperature oscillation amplitude, is a system start-stop angular frequency, is a thermal hysteresis model strength coefficient, is a thermal relaxation time reciprocal, T0 is an initial temperature, and α and β are both temperature change coefficients.

[0020] In the present application, preferably, S2 converts the collected smoke concentration, flammable gas and temperature into standard values respectively, and the conversion rule is: average all original collection values, compare the average value with the maximum value of all original collection values, if the number of the maximum value greater than the average value exceeds 10% of the average value, then take the average value as the standard value; if the number of the maximum value greater than the average value does not exceed 10% of the average value, then take the maximum value as the standard value.

[0021] In the present application, preferably, S5 includes: S51, if the warning level is a first-level warning, an alarm signal is sent, the tail exhaust ventilation is opened, and the refrigerating capacity is increased; S52, if the warning level is a second-level warning, a strengthened alarm signal is sent, the fire extinguishing device is prepared to be started, the main relay is closed, the warehouse door is closed, the heptafluoropropane fire extinguisher is opened, and the battery coolant flow is increased; S53, if the warning level is a third-level warning, the fire extinguishing device is started, the ventilation system is closed, and the water pipe electromagnetic valve is opened; S54, if the water level reaches the liquid level threshold, a liquid level alarm is sent, and the water pipe electromagnetic valve is closed.

[0022] In the present application, preferably, the smoke concentration threshold value is 10 ppm, the flammable gas concentration threshold value is 50 ppm, the temperature threshold value is 60℃, and the liquid level threshold value is 50 mm.

[0023] The power battery thermal runaway early warning system based on multiple physical fields comprises: a collection module, which is used for collecting smoke concentration, flammable gas concentration and temperature at different positions in the environment; a standardization module, which is used for converting the collected smoke concentration, flammable gas and temperature into standard values respectively; a prediction module, which is used for calculating smoke concentration prediction value, flammable gas concentration prediction value, temperature prediction value and temperature rise rate prediction value by using the smoke concentration standard value, flammable gas concentration standard value and temperature standard value respectively; a determination module, which is used for determining the early warning level by using early warning determination rules through the smoke concentration prediction value, flammable gas concentration prediction value, temperature prediction value and temperature rise rate prediction value; and an early warning execution module, which is used for executing early warning measures according to the early warning level; the early warning level comprises first-level early warning, second-level early warning and third-level early warning; and the early warning determination rules comprise: if the smoke concentration prediction value reaches the smoke concentration threshold value and / or the flammable gas concentration prediction value reaches the flammable gas concentration threshold value, or the temperature prediction value reaches the temperature threshold value, the first-level early warning is determined; if the smoke concentration prediction value reaches the smoke concentration threshold value or the flammable gas concentration prediction value reaches the flammable gas concentration threshold value, and at the same time, the temperature prediction value reaches the temperature threshold value, the second-level early warning is determined; and if the smoke concentration prediction value reaches the smoke concentration threshold value, the flammable gas concentration prediction value reaches the flammable gas concentration threshold value, the temperature prediction value reaches the temperature threshold value and the temperature rise rate prediction value reaches the temperature rise rate threshold value at the same time, the third-level early warning is determined.

[0024] In the application, preferably, the smoke concentration prediction value is calculated by using the smoke concentration standard value, and the prediction model adopted is as follows:

[0025]

[0026] In the formula, C(t) is the smoke concentration prediction value, C0 is the smoke concentration standard value, is the turbulent flow entrainment intensity coefficient, is the turbulent flow decay coefficient, is the turbulent flow vortex shedding angular frequency, λ is the smoke concentration growth rate constant, and t is time;

[0027] The flammable gas concentration prediction value is calculated by using the flammable gas concentration standard value, and the prediction model adopted is as follows:

[0028]

[0029] In the formula, G(t) is the flammable gas concentration prediction value, G0 is the flammable gas concentration standard value, is the gas release saturation rate, k is the flammable gas concentration increase rate, and t is time;

[0030] The temperature prediction value and the temperature rise rate prediction value are calculated by using the temperature standard value, and the prediction model adopted is as follows:

[0031] ΔT = dT / dt = α + 2βt

[0032] In the formula, T(t) is a temperature prediction value, ΔT is a temperature rise rate prediction value, is a temperature standard value, is a thermal relaxation time, is a temperature oscillation amplitude, is a system start-stop angular frequency, is a thermal hysteresis model strength coefficient, is a thermal relaxation time reciprocal, T0 is an initial temperature, and α and β are temperature change coefficients.

[0033] The collected smoke concentration, flammable gas and temperature are converted into standard values respectively, and the conversion rule is that: the average value of all original collection values is obtained, and the average value is compared with the maximum value of all original collection values, if the number of the maximum value greater than the average value exceeds 10% of the average value, the average value is taken as the standard value, if the number of the maximum value greater than the average value does not exceed 10% of the average value, the maximum value is taken 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 DEG C.

[0034] In the application, preferably, the early warning execution module comprises: a first-level early warning execution unit, which is used for issuing an alarm signal, opening a tail exhaust ventilation, and increasing a refrigerating capacity if the early warning level is a first-level early warning; a second-level early warning execution unit, which is used for issuing an enhanced alarm signal, preparing to start a fire extinguishing device, closing a main relay, closing a warehouse door, opening a heptafluoropropane fire extinguisher, and increasing a battery cooling liquid flow if the early warning level is a second-level early warning; a third-level early warning execution unit, which is used for starting the fire extinguishing device, closing a ventilation system, and opening a water pipe electromagnetic valve if the early warning level is a third-level early warning; and a liquid level early warning execution unit, which is used for issuing a liquid level alarm and closing the water pipe electromagnetic valve if a water liquid level reaches a liquid level threshold value; the liquid level early warning execution unit comprises a water liquid level sensor, which is used for detecting a water liquid level height, and the liquid level threshold value is set to 50 mm; and the collection module comprises: at least 6 temperature sensors, 4 of which are arranged on a surface of a battery module, 1 of which is arranged on a top of an environmental warehouse body, and 1 of which is arranged at an exhaust port; at least 2 smoke sensors, which are respectively located at a top and a bottom of the environmental warehouse body; and at least 3 flammable gas sensors, 1 of which is arranged near a battery pressure relief valve, and 2 of which are located at corners of the environmental warehouse body and are distributed in diagonal lines.

[0035] Compared with the prior art, the application has the following beneficial effects:

[0036] (1) Reduce safety risks: A multifunctional power battery safety prevention and control system is provided, which can effectively reduce the risk of power battery thermal runaway, protect the safety of personnel and equipment in environmental warehouses, laboratories and other places, and reduce personnel casualties and property losses caused by power battery fires.

[0037] (2) Improve early warning accuracy and response speed: Precise and rapid early warning of power battery thermal runaway fire is achieved, which has higher accuracy and faster response speed compared with traditional early warning systems, can timely discover hidden dangers at the early stage of fire, prevent trouble from happening, and gain valuable time for taking fire extinguishing measures.

[0038] (3) Enhance fire extinguishing effect and isolation ability: Through efficient fire-fighting isolation measures, the possibility of fire spreading is minimized, fire loss is reduced, the safety and reliability of power batteries during use are improved, and the fire can be controlled and extinguished at the first time to avoid the expansion of the fire to cause greater damage to surrounding equipment and environment. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 The flowchart of the power battery thermal runaway early warning method based on multiple physical fields of an embodiment of the present application.

[0040] Figure 2 The flowchart of the flowchart of the power battery thermal runaway early warning method based on multiple physical fields of another embodiment of the present application.

[0041] Figure 3 The structural schematic diagram of the power battery thermal runaway early warning system based on multiple physical fields of another embodiment of the present application.

[0042] Figure 4 The structural schematic diagram of the early warning execution module in the power battery thermal runaway early warning system based on multiple physical fields of another embodiment of the present application.

[0043] In the drawings: 1, acquisition module; 2, standardization module; 3, prediction module; 4, determination 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 DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0045] It should be understood that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements can also be present. In addition, it should be understood that when an element is referred to as being "connected, coupled, or "disposed" to another element, it can be directly connected, coupled, or disposed to the other element or intervening elements can also be present. As used herein, the terms "vertical", "horizontal", "left", "right", and the like are merely for the purpose of illustration and are not intended to limit the present application.

[0046] 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 application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0047] See Figure 1 A preferred embodiment of the present application provides a multi-physical field-based power battery thermal runaway early warning method, comprising:

[0048] S1, collecting smoke concentration, flammable gas concentration and temperature at different positions in the environment.

[0049] In the environment warehouse, laboratory and other environments, smoke sensors, flammable gas sensors and temperature sensors are arranged, and the sensors are used to collect smoke concentration, flammable gas concentration and temperature data. The number of various sensors is more than 2, and they are arranged at different positions in the environment to obtain more comprehensive and accurate smoke concentration, flammable gas concentration and temperature data.

[0050] In this embodiment, preferably, the sensor group uses 6 temperature sensors (response speed 10 ms level, accuracy ±0.5℃), of which 4 are arranged on the surface of the battery module, 1 is arranged on the top of the warehouse body, and 1 is arranged at the air outlet; 2 smoke sensors (photoelectric type, range 0-1000 ppm) are respectively located at the top and bottom of the warehouse body; 3 flammable gas sensors (catalytic combustion type, detecting HF, THC, CO, etc., range 0-100 ppm), one of which is close to the battery pressure relief valve, and the other two are located at the corners of the warehouse body (diagonal distribution); one water level sensor, using a floating ball type, is installed in the drain groove at the bottom of the warehouse body to detect whether the water level reaches the upper limit (trigger value 50 mm).

[0051] S2, respectively converting the collected smoke concentration, flammable gas and temperature into standard values.

[0052] Since the number of smoke sensors, flammable gas sensors and temperature sensors is more than 2, the obtained data cannot be directly used for early warning calculation, and the data collected by the same type of sensors need to be fused, and the fused data is used as a standard value for subsequent early warning calculation.

[0053] Preferably, the collected smoke concentration, flammable gas and temperature are converted into standard values respectively, and the conversion rule is: the average value of all original collected values is calculated, and the maximum value of the average value is compared with all original collected values, if the number of the maximum value greater than the average value exceeds 10% of the average value, the average value is taken as the standard value; if the number of the maximum value greater than the average value does not exceed 10% of the average value, the maximum value is taken as the standard value. For example, the temperature values collected by 6 temperature sensors are calculated to obtain an average temperature value, and the maximum temperature value among the temperature values collected by the 6 temperature sensors is compared with the average temperature value, if the difference between the two is greater than 10% of the average temperature value, it is considered that the maximum temperature value is an abnormal value, and the average temperature value is taken as the temperature standard value; if the difference between the two is not greater than 10% of the average value, the maximum temperature value is a normal value, and the maximum temperature value is taken as the temperature standard value, which maximizes the early warning effect.

[0054] S3, respectively using the smoke concentration standard value, the flammable gas concentration standard value and the temperature standard value to calculate the smoke concentration prediction value, the flammable gas concentration prediction value, the temperature prediction value and the temperature rise rate prediction value.

[0055] Through the prediction model and the standard value, the change of the smoke concentration, the flammable gas concentration and the temperature in the environment bin in a certain period of time in the future can be predicted, and the thermal runaway of the power battery can be judged in advance to perform early warning.

[0056] Preferably, the smoke concentration prediction value is calculated by using the smoke concentration standard value, and the prediction model used is:

[0057]

[0058] In the formula, the integral term is to simulate the randomness of turbulent diffusion, C(t) is the smoke concentration prediction value, with unit of ppm; C0 is the initial smoke concentration (smoke concentration standard value), with unit of ppm; is the turbulent entrainment aversion intensity coefficient, with unit of ppm / s; is the turbulent decay coefficient, with unit of s -1 ; is the turbulent vortex shedding angular frequency, with unit of rad / s; λ is the smoke concentration growth rate constant, t is time; C th is the smoke concentration threshold, which is set to 10 ppm, when C(t)≥C th , the smoke data early warning is triggered, that is, the smoke concentration prediction value reaches the smoke concentration threshold.

[0059] Preferably, the combustible gas concentration prediction value is calculated using the combustible gas concentration standard value, and the prediction model used is:

[0060]

[0061] In the formula, G(t) is the combustible gas concentration prediction value, with units of ppm; G0 is the initial combustible gas concentration (combustible gas concentration standard value), with units of ppm; is the gas release saturation rate, with units of s -1 ; k is the combustible gas concentration increase rate, with units of ppm / s; t is time. G th is the combustible gas concentration threshold value, set to 50 ppm, and when G≥G th , a combustible gas data warning is triggered, i.e., the combustible gas concentration prediction value reaches the combustible gas concentration threshold value.

[0062] Preferably, the temperature prediction value and the temperature rise rate prediction value are calculated using the temperature standard value, and the prediction model used is:

[0063] , ΔT = dT / dt = α + 2βt

[0064] In the formula, the integral term is a thermal hysteresis model, describing the delay effect of heat transfer. T(t) is the temperature prediction value, with units of ℃; ΔT is the temperature rise rate prediction value, with units of ℃ / s; T0 is the initial temperature (temperature standard value), with units of ℃; is the thermal relaxation time, is the temperature oscillation amplitude, with units of ℃; is the system start-stop angular frequency, with units of rad / s; is the strength coefficient of the thermal hysteresis model, is the inverse of the thermal relaxation time, with units of s -1 ; T0 is the initial temperature, and α and β are both temperature change coefficients, generally obtained through experimental data fitting. T th is the temperature threshold value, set to 60 ℃ and 70 ℃; ΔT th is the temperature rise rate threshold value, set to 5 ℃ / s, and when T≥T th , ΔT≥ΔT th , a temperature data warning is triggered, i.e., the temperature prediction value reaches the temperature threshold value, and the temperature rise rate prediction value reaches the temperature rise rate threshold value.

[0065] S4, the warning level is determined using the smoke concentration prediction value, the combustible gas concentration prediction value, the temperature prediction value, and the temperature rise rate prediction value through a warning determination rule.

[0066] Specifically, the early warning levels include a first level early warning, a second level early warning and a third level early warning. The early warning determination rules include:

[0067] (1) If the smoke concentration prediction value reaches the smoke concentration threshold value and / or the flammable gas concentration prediction value reaches the flammable gas concentration threshold value, or the temperature prediction value reaches the temperature threshold value, it is determined as the first level early warning;

[0068] (2) If the smoke concentration prediction value reaches the smoke concentration threshold value or the flammable gas concentration prediction value reaches the flammable gas concentration threshold value, and at the same time the temperature prediction value reaches the temperature threshold value, it is determined as the second level early warning;

[0069] (3) If the smoke concentration prediction value reaches the smoke concentration threshold value, the flammable gas concentration prediction value reaches the flammable gas concentration threshold value, the temperature prediction value reaches the temperature threshold value, and the temperature rise rate prediction value reaches the temperature rise rate threshold value, it is determined as the third level early warning.

[0070] Preferably, the smoke concentration threshold value is 10 ppm, the flammable gas concentration threshold value is 50 ppm, and the temperature threshold value is 60℃.

[0071] S5, performing early warning measures according to the early warning level.

[0072] Specifically, as shown in FIG. 5, S5 includes: Figure 2

[0073] S51, if the early warning level is the first level early warning, an alarm signal is sent, the tail exhaust ventilation is turned on, and the refrigerating capacity is increased.

[0074] When the first level early warning is triggered, the system sends an alarm signal to remind the staff to pay attention to the situation in the environmental warehouse, and takes preventive measures such as turning on the tail exhaust ventilation and increasing the refrigerating capacity.

[0075] S52, if the early warning level is the second level early warning, a strengthened alarm signal is sent, the fire extinguishing device is prepared to be started, the main relay is turned off, the warehouse door is closed, the heptafluoropropane fire extinguisher is turned on, and the battery coolant flow is increased.

[0076] When the second level early warning is triggered, the system further strengthens the alarm signal and notifies the central control unit to prepare to start the fire extinguishing device. Response measures such as turning off the main relay, closing the warehouse door, turning on the heptafluoropropane fire extinguisher, and increasing the battery coolant flow are taken.

[0077] S53, if the early warning level is the third level early warning, the fire extinguishing device is started, the ventilation system is turned off, and the water pipe electromagnetic valve is turned on.

[0078] When the third level early warning is triggered, it indicates that there are obvious signs of fire in the environmental warehouse. The system will immediately start the fire extinguishing device, and at the same time turn off the ventilation system of the environmental warehouse to prevent the spread of fire. Corresponding measures such as turning on the water pipe electromagnetic valve are taken. ​

[0079] S54, if the water level reaches the threshold, the liquid level alarm is issued, and the water pipe electromagnetic valve is closed.

[0080] When the water level sensor detects that the water level reaches the upper limit, an alarm will also be issued, and measures such as closing the water pipe electromagnetic valve will be taken.

[0081] Preferably, the liquid level threshold is set to 50mm. The water level sensor can be a floating ball type installed in the drain groove at the bottom of the bin body to detect whether the water level reaches the upper limit (liquid level threshold).

[0082] As shown in Figure 3 Another embodiment of the present application also provides a power battery thermal runaway early warning system based on multiple physical fields, which comprises:

[0083] The acquisition module 1 is used to acquire the smoke concentration, flammable gas concentration and temperature at different positions in the environment.

[0084] Specifically, the acquisition module 1 comprises: at least 6 temperature sensors, of which 4 are arranged on the surface of the battery module, 1 is arranged at the top of the environment bin body, and 1 is arranged at the air outlet; at least 2 smoke sensors are respectively located at the top and bottom of the environment bin body; and at least 3 flammable gas sensors, of which 1 is arranged near the battery pressure relief valve, and 2 are located at the corners of the environment bin body and are distributed in diagonal lines.

[0085] The standardization module 2 is used to convert the acquired smoke concentration, flammable gas and temperature into standard values respectively.

[0086] The prediction module 3 is used to calculate the smoke concentration prediction value, flammable gas concentration prediction value, temperature prediction value and temperature rise rate prediction value by using the smoke concentration standard value, flammable gas concentration standard value and temperature standard value respectively.

[0087] The determination module 4 is used to determine the early warning level by using the smoke concentration prediction value, flammable gas concentration prediction value, temperature prediction value and temperature rise rate prediction value according to the early warning determination rule.

[0088] The early warning execution module 5 is used to execute the early warning measures according to the early warning level.

[0089] Specifically, as shown in Figure 4 The early warning execution module 5 comprises:

[0090] The first early warning execution unit 51 is used to issue an alarm signal, start the tail exhaust ventilation, and increase the refrigerating capacity if the early warning level is the first early warning.

[0091] The secondary early warning execution unit 52 is configured to send a strengthened alarm signal, start the fire extinguishing device, close the main relay, close the door, open the heptafluoropropane fire extinguisher, and increase the flow of battery coolant if the early warning level is secondary early warning.

[0092] The tertiary early warning execution unit 53 is configured to start the fire extinguishing device, close the ventilation system, and open the water pipe electromagnetic valve if the early warning level is tertiary early warning.

[0093] The liquid level early warning execution unit 54 is configured to send a liquid level alarm and close the water pipe electromagnetic valve if the water level reaches the upper limit.

[0094] The liquid level early warning execution unit 54 includes a water level sensor configured to detect the water level height, and the liquid level threshold is set to 50 mm.

[0095] The early warning levels include primary early warning, secondary early warning, and tertiary early warning.

[0096] The early warning determination rules include:

[0097] If the smoke concentration prediction value reaches the smoke concentration threshold value and / or the flammable gas concentration prediction value reaches the flammable gas concentration threshold value, or the temperature prediction value reaches the temperature threshold value, it is determined as primary early warning.

[0098] If the smoke concentration prediction value reaches the smoke concentration threshold value or the flammable gas concentration prediction value reaches the flammable gas concentration threshold value, and at the same time the temperature prediction value reaches the temperature threshold value, it is determined as secondary early warning.

[0099] If the smoke concentration prediction value reaches the smoke concentration threshold value, the flammable gas concentration prediction value reaches the flammable gas concentration threshold value, the temperature prediction value reaches the temperature threshold value, and the temperature rise rate prediction value reaches the temperature rise rate threshold value, it is determined as tertiary early warning.

[0100] The smoke concentration prediction value is calculated using the smoke concentration standard value, and the prediction model used is:

[0101]

[0102] In the formula, C(t) is the smoke concentration prediction value, C0 is the smoke concentration standard value, is the turbulent entrainment intensity coefficient, is the turbulent decay coefficient, is the turbulent vortex shedding angular frequency, λ is the smoke concentration growth rate constant, and t is time.

[0103] The flammable gas concentration prediction value is calculated using the flammable gas concentration standard value, and the prediction model used is:

[0104]

[0105] In the formula, G(t) is the combustible gas concentration prediction value, G0 is the combustible gas concentration standard value, is the gas release saturation rate, k is the combustible gas concentration increase rate, and t is time.

[0106] The temperature prediction value and the temperature rise rate prediction value are calculated by using the temperature standard value, and the prediction model used is:

[0107] , ΔT = dT / dt = α + 2βt

[0108] In the formula, T(t) is the temperature prediction value, ΔT is the temperature rise rate prediction value, is the temperature standard value, is the thermal relaxation time, is the temperature oscillation amplitude, is the system start-stop angular frequency, is the strength coefficient of the thermal hysteresis model, is the reciprocal of the thermal relaxation time, T0 is the initial temperature, and α and β are temperature change coefficients.

[0109] The collected smoke concentration, combustible gas and temperature are converted into standard values respectively, and the conversion rule is: the average value of all original collection values is obtained, and the average value is compared with the maximum value of all original collection values, if the number of the maximum value greater than the average value exceeds 10% of the average value, the average value is taken as the standard value, if the number of the maximum value greater than the average value does not exceed 10% of the average value, the maximum value is taken as the standard value.

[0110] The smoke concentration threshold is 10 ppm, the combustible gas concentration threshold is 50 ppm, and the temperature threshold is 60 DEG C.

[0111] The power battery thermal runaway early warning method and system based on multiple physical fields of the application realize accurate and rapid early warning of the environmental warehouse power battery thermal runaway fire, compared with the traditional early warning system, have higher accuracy and faster response speed. By comprehensively using temperature, smoke, combustible gas and other multiple physical field information, hidden dangers can be found in time at the early stage of fire, and preventive measures can be taken to gain time for taking fire extinguishing measures.

[0112] The above description is a detailed description of the preferred embodiments of the application, but the embodiments are not used to limit the scope of the patent application of the application, and any equivalent changes or modifications made under the technical spirit of the application should belong to the patent scope covered by the application.

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 at the same time, it is identified as a Level III warning. 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) This is the predicted value for smoke concentration. C0 This is the standard value for smoke concentration. The turbulent entrainment aversion intensity coefficient is... The turbulence attenuation coefficient is... The angular frequency of turbulent eddy shedding. λ The rate constant of smoke concentration growth is... t For 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) This is a predicted value for flammable gas concentration. G0 This refers to the standard value for flammable gas concentration. The gas release saturation rate, k For the rate of increase of flammable gas concentration, t For 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) This is a predicted temperature value. ΔT This is the predicted rate of temperature rise. T0 This 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... It is the reciprocal of the thermal relaxation time. α、β All are temperature change coefficients.

2. 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.

3. 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.

4. The method for early warning of thermal runaway of power batteries based on multiphysics fields according to claim 3, 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.

5. A power battery thermal runaway early warning system based on multiphysics fields, 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 at the same time, it is identified as a Level III warning. 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) This is the predicted value for smoke concentration. C0 This is the standard value for smoke concentration. The turbulent entrainment aversion intensity coefficient is... The turbulence attenuation coefficient is... The angular frequency of turbulent eddy shedding. λ The rate constant of smoke concentration growth is... t For 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) This is a predicted value for flammable gas concentration. G0 This refers to the standard value for flammable gas concentration. The gas release saturation rate, k For the rate of increase of flammable gas concentration, t For 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) This is a predicted temperature value. ΔT This is the predicted rate of temperature rise. 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... It is the reciprocal of the thermal relaxation time. α、β The coefficient of temperature change; 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.

6. The power battery thermal runaway early warning system based on multiphysics fields according to claim 5, 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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