Lithium battery thermal runaway early warning method for parking lot

Abstract

The invention discloses a lithium battery thermal runaway early warning method for a parking lot, and the method comprises the steps: obtaining a temperature image through an infrared imaging sensor, and obtaining a high-temperature area proportion and a high-temperature duration through the calculation of the temperature image; acquiring current smoke concentration data and duration exceeding a first concentration threshold value through the smoke sensor; inputting the high-temperature area proportion, the high-temperature duration, the smoke concentration data and the duration exceeding the first concentration threshold value into a pre-trained stage prediction model to obtain the thermal runaway stage of the current lithium battery and the probability of the thermal runaway stage; and if the probability of the thermal runaway stage of the current lithium battery exceeds a first probability threshold value, fireproof treatment and early warning of the corresponding stage are carried out.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery thermal runaway warning, and in particular to a lithium battery thermal runaway warning method for a parking lot. Background Art

[0002] With the popularity of electric vehicles and the development of charging infrastructure, electric vehicles and hybrid vehicles powered by lithium batteries are becoming more and more common. These vehicles typically use high-energy-density lithium batteries to provide longer driving range and higher energy efficiency.

[0003] However, lithium batteries themselves have potential safety hazards. If the vehicle experiences a collision or other physical damage before parking, it may damage the structure of the battery, causing the battery cell to short-circuit or internal short-circuit, thereby causing thermal runaway. Overcharging may lead to excessive voltage, which will increase the temperature inside the battery and cause thermal runaway. Although the battery management system usually has a protection mechanism, such problems may still occur if the system fails or is improperly set up; further, in a high-temperature parking lot, the ambient temperature may cause the battery temperature to rise. If the cooling system fails, the accumulated heat may exceed the safety threshold of the battery; in addition, incorrect electrical wiring or poor contact may cause arcing or abnormal current flow, all of which may cause thermal runaway; after a lithium battery has thermal runaway, it is easy to cause a fire due to high temperature, short circuit, etc., resulting in serious property damage and casualties.

[0004] Currently, many parking lots are not equipped with sufficiently advanced monitoring and fire extinguishing systems to deal with the specific risks of lithium battery fires, which results in a slow response when accidents occur, and an inability to take effective measures in the early stages of the accident to prevent the spread of fire. Some parking lots are equipped with partial monitoring systems, but these monitoring systems only monitor whether there are signs of fire and take fire extinguishing measures. They cannot monitor the status of lithium batteries in the early stages of thermal runaway, and cannot take effective measures to prevent fires in the early stages of thermal runaway.

[0005] The purpose of the present invention is to design a lithium battery thermal runaway warning method for parking lots in view of the above-mentioned problems in the prior art. Summary of the invention

[0006] In view of this, an object of the present invention is to provide a lithium battery thermal runaway early warning method for a parking lot, which can solve the above-mentioned problems.

[0007] The present invention provides a lithium battery thermal runaway early warning method for a parking lot, based on a lithium battery thermal runaway early warning system for a parking lot, the system comprising: The infrared imaging sensor is set in the middle of the parking space with the imaging direction facing upwards to monitor the temperature changes of the lithium battery; The smoke sensor is located in the middle of the parking space to monitor the smoke concentration generated by thermal runaway of the lithium battery; A controller, connected to the temperature sensor and the smoke sensor, respectively, for obtaining the temperature and smoke concentration data of the lithium battery, analyzing the current thermal runaway stage of the lithium battery according to the temperature and smoke concentration data, and generating treatment measures and warning information; The method comprises: Acquire a temperature image through the infrared imaging sensor, and calculate the high temperature area ratio and high temperature duration through the temperature image; Acquiring current smoke concentration data and a duration exceeding a first concentration threshold through the smoke sensor; The high-temperature area ratio, high-temperature duration, smoke concentration data, and duration exceeding the first concentration threshold are input into the pre-trained stage prediction model to obtain the current thermal runaway stage of the lithium battery and its probability; If the thermal runaway stage probability of the current lithium battery exceeds a first probability threshold, fire prevention processing and early warning of the corresponding stage are performed.

[0008] Further, the step of acquiring a temperature image by using the infrared imaging sensor and calculating the high temperature area ratio and the high temperature duration by using the temperature image comprises: Acquire a temperature distribution image of the bottom of the vehicle by using the infrared imaging sensor, and pre-process the temperature distribution image to obtain a standard temperature distribution image; Segmenting the standard temperature distribution image into high temperature areas according to a first temperature threshold to obtain high temperature areas; Calculating the total number of pixels in the standard distribution image and the number of high-temperature pixels in the high-temperature area, and calculating the high-temperature area ratio according to the total number of pixels and the number of high-temperature pixels; The number of frames of the standard distribution image with the same high temperature area ratio is calculated, and the high temperature duration is calculated according to the number of frames and the frame interval.

[0009] Furthermore, the high temperature region segmentation is performed on the standard temperature distribution image according to the first temperature threshold, and the high temperature region includes: Acquire each frame of the standard temperature distribution image, and apply the first temperature threshold to each frame of the standard temperature distribution image; Pixels exceeding the first temperature threshold are marked as 1, and pixels not exceeding the first temperature threshold are marked as 0, thereby obtaining a high temperature area.

[0010] Furthermore, the calculation formula of the high temperature area ratio is: .

[0011] Further, the calculation formula of the high temperature time is: .

[0012] Furthermore, the stage prediction model is trained through the following steps: Collect data on the percentage of high-temperature area, duration of high temperature, smoke density, and duration of exceeding the first concentration threshold, divide the percentage of high-temperature area, duration of high temperature, smoke density, and duration of exceeding the first concentration threshold into several time series samples, calibrate the thermal runaway stage and its probability of each time series sample, and form a stage prediction sample training set; The stage prediction model is constructed by a neural network model, and the stage prediction model is trained by a stage prediction sample training set to obtain the parameters of the stage prediction model.

[0013] Furthermore, the controller is remotely connected to the fan of the parking lot fresh air system for adjusting the wind speed according to the current thermal runaway stage of the lithium battery; The controller is remotely connected to a spray device, which is disposed on the ground behind the parking space and is used to spray and extinguish fire according to the thermal runaway stage of the lithium battery. The controller is remotely connected to a fire protection device, which is arranged above the parking space and is used to prevent fire according to the current thermal runaway stage of the lithium battery.

[0014] Furthermore, the fire prevention device includes: a plurality of fireproof rolling curtains, which are respectively arranged between adjacent parking spaces and are used to isolate the flames of adjacent parking spaces.

[0015] Furthermore, the fire prevention treatment and early warning at the corresponding stage include: If the current thermal runaway stage of the lithium battery is in the early stage, the spray device is started and remote warning information is uploaded; If the current thermal runaway stage of the lithium battery is in the middle stage, the water spraying amount of the spraying device is increased, the speed of the fan is adjusted to the maximum value, and the remote warning information is uploaded; If the current thermal runaway stage of the lithium battery is in the late stage, the sprinkler device is adjusted to the maximum water spray volume and the fire prevention device is activated, and the remote warning information is uploaded.

[0016] Furthermore, the warning information includes: parking space number, current thermal runaway stage of the lithium battery and its probability, and fire prevention measures.

[0017] Beneficial effects of the present invention: First, the temperature image is obtained through the infrared imaging sensor, the high-temperature area ratio and high-temperature duration are automatically calculated, the early characteristics of thermal runaway of the lithium battery are captured, and the accuracy of the prediction of the thermal runaway stage of the lithium battery is improved.

[0018] Secondly, by using infrared imaging sensors and smoke sensors, multi-dimensional detection of temperature (percentage of high temperature and duration of high temperature) and smoke concentration is achieved, which can more comprehensively and accurately evaluate the thermal runaway state of lithium batteries.

[0019] Third, the acquired data is analyzed through the pre-trained stage prediction model to accurately predict the thermal runaway stage and probability of the lithium battery.

[0020] Fourth, through corresponding fire prevention treatment and early warning, the ability to respond quickly to potential risks has been improved, so that measures can be taken before the thermal runaway stage develops into a critical state. The phased response measures are more targeted and help optimize the use of resources and measures at different risk levels. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a system module diagram of the first embodiment.

[0023] Figure 2 This is a diagram of the module installation position of the first embodiment.

[0024] Figure 3 It is a flow chart of the method of embodiment 2. DETAILED DESCRIPTION

[0025] To facilitate understanding by those skilled in the art, the structure of the present invention is now further described in detail with reference to the embodiments and the accompanying drawings. It should be understood that the steps mentioned in the present embodiment, unless otherwise specified in their order, can be adjusted in order according to actual needs, and can even be executed simultaneously or partially simultaneously.

[0026] Embodiment 1 like Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a lithium battery thermal runaway warning system for a parking lot, comprising: The infrared imaging sensor is set in the middle of the parking space with the imaging direction facing upwards to monitor the temperature changes of the lithium battery; The smoke sensor is located in the middle of the parking space to monitor the smoke concentration generated by thermal runaway of the lithium battery; A controller, connected to the temperature sensor and the smoke sensor, respectively, for obtaining the temperature and smoke concentration data of the lithium battery, analyzing the current thermal runaway stage of the lithium battery according to the temperature and smoke concentration data, and generating treatment measures and warning information; The controller is remotely connected to the fan of the parking lot fresh air system for adjusting the wind speed according to the current thermal runaway stage of the lithium battery; The controller is remotely connected to a spray device, which is disposed on the ground behind the parking space and is used to spray and extinguish fire according to the thermal runaway stage of the lithium battery. The controller is remotely connected to a fire protection device, which is arranged above the parking space and is used to prevent fire according to the current thermal runaway stage of the lithium battery.

[0027] Furthermore, the fire prevention device includes: a plurality of fireproof rolling curtains, which are respectively arranged between adjacent parking spaces and are used to isolate the flames of adjacent parking spaces.

[0028] In this embodiment, thermal runaway may occur in lithium batteries, and traditional monitoring equipment is difficult to perceive early danger signals in a timely and accurate manner. Therefore, infrared imaging sensors are used on parking spaces to monitor temperature changes. Most batteries with electric vehicles are set at the bottom, which can achieve early detection of thermal runaway of lithium batteries; smoke sensors increase the sensitivity to thermal runaway and provide timely data on smoke concentration, which helps to identify the occurrence of early fires.

[0029] It is difficult to effectively coordinate various emergency equipment (fresh air system, fire extinguishing sprinkler system) in existing parking lots, so it is impossible to make a comprehensive response in time when a fire occurs. The controller can analyze various sensor data in real time and predict the thermal runaway stage of the lithium battery, and generate corresponding treatment measures and early warning information. According to the early warning information, the wind speed of the fresh air system is automatically adjusted, the sprinkler fire extinguishing system is started, and the fire prevention device is started to ensure the best response to the fire source in the shortest time. The sprinkler system is set on the ground behind the parking space. Since most parking spaces are not surrounded by walls and most electric vehicles have lithium batteries set at the bottom of the vehicle, the sprinkler system needs to spray the lithium battery position in a targeted manner. The conventional parking lot sprinkler is set above the parking space and cannot spray and cool down the lithium battery at each stage of thermal runaway. According to demand, the rotation remote control function of the sprinkler can also be added so that the sprinkler can adjust the spray position in a targeted manner.

[0030] Fire spreads quickly, especially in parking lots with dense traffic or small spaces. Existing fire prevention measures may not be fast enough to effectively control the spread of fire. The application of fire shutters can physically block the spread of fire between adjacent parking spaces, effectively limit the spread of flames, provide early detection and response mechanisms, and help control the situation before the disaster expands, thereby reducing vehicle losses and other property losses.

[0031] The fresh air system, the sprinkler device and the fireproof roller shutter are prior arts, and the present invention does not make any structural improvements or elaborate on them.

[0032] Embodiment 2 like Figure 3 As shown, an embodiment of the present invention provides a lithium battery thermal runaway warning method for a parking lot, comprising: S1 obtains a temperature image through the infrared imaging sensor, and obtains the high temperature area ratio and high temperature duration through calculation of the temperature image; S101 acquires a temperature distribution image of the bottom of the vehicle through the infrared imaging sensor, and pre-processes the temperature distribution image to obtain a standard temperature distribution image; S102 performs high temperature area segmentation on the standard temperature distribution image according to a first temperature threshold to obtain a high temperature area; S1021 acquires each frame of the standard temperature distribution image, and applies the first temperature threshold to each frame of the standard temperature distribution image; S1022 marks pixels exceeding the first temperature threshold as 1, and marks pixels not exceeding the first temperature threshold as 0, thereby obtaining a high temperature area.

[0033] Specifically, the calculation formula for the high temperature area ratio is: .

[0034] In this step, due to the large area of ​​lithium batteries, traditional point temperature monitoring is difficult to capture the distribution of overheated parts of lithium batteries over a large area, and cannot accurately identify and locate early signs of thermal runaway. Therefore, infrared imaging is used to calculate the high-temperature area ratio, and real-time processing of each frame of temperature distribution image is achieved. By applying temperature thresholds, high-temperature areas are quickly and automatically marked, avoiding the time and labor costs required for manual intervention. The first temperature threshold can be 100°C. At this temperature threshold, the battery's electrolyte may begin to decompose and generate heat, which is generally considered to be the beginning of thermal runaway.

[0035] S103: calculating the total number of pixels in the standard distribution image and the number of high-temperature pixels in the high-temperature area, and calculating the high-temperature area ratio according to the total number of pixels and the number of high-temperature pixels; S104 calculates the number of frames of the standard distribution image with the same high temperature area ratio, and calculates the high temperature duration according to the number of frames and the frame interval.

[0036] Specifically, the calculation formula for the high temperature time is: .

[0037] In this step, relying solely on a single indicator (high temperature area) may not fully reflect the current thermal runaway risk of the battery. For example, when an electric vehicle enters a parking lot from an external high-temperature environment, the lithium battery of the electric vehicle may become partially hot. Therefore, if only relying on a single indicator temperature for identification at this time, identification errors may occur. Therefore, it is also necessary to combine the duration of high temperature. Since the thermal runaway of lithium batteries is an ongoing process, the high temperature time will be extended, providing multi-dimensional thermal runaway monitoring parameters. These parameters can provide more information for the analysis and prediction of the battery's thermal runaway state.

[0038] S2 obtains the current smoke concentration data and the duration of exceeding the first concentration threshold through the smoke sensor; In this step, in order to avoid the failure of the infrared imaging sensor, a smoke sensor is added. The lithium battery has an internal electrolyte reaction at the initial stage of combustion, and the battery produces smoke after combustion. Therefore, adding smoke concentration can assist in monitoring the thermal runaway state of the lithium battery, especially when the battery begins to burn. It can determine the stage of thermal runaway that the lithium battery has reached. By using infrared imaging sensors and smoke sensors, the high-temperature area ratio, high-temperature duration, smoke concentration and other parameters are comprehensively calculated to provide comprehensive thermal runaway stage monitoring.

[0039] S3 inputs the high temperature area ratio, high temperature duration, smoke concentration data, and duration exceeding the first concentration threshold into the pre-trained stage prediction model to obtain the current thermal runaway stage of the lithium battery and its probability; Furthermore, the stage prediction model is trained through the following steps: S301 collects the high-temperature area ratio, high-temperature duration, smoke density data, and duration data exceeding a first concentration threshold, divides the high-temperature area ratio, high-temperature duration, smoke density data, and duration exceeding the first concentration threshold into a number of time series samples, calibrates the thermal runaway stage and its probability of each time series sample, and forms a stage prediction sample training set; S302 constructs the stage prediction model through a neural network model, trains the stage prediction model through a stage prediction sample training set, and obtains parameters of the stage prediction model.

[0040] In this step, the stage prediction model constructed using a neural network can deeply learn multi-dimensional data features, overcome the limitations of simple linear models, and improve the effectiveness and accuracy of thermal runaway prediction.

[0041] S4: If the probability of the thermal runaway stage of the current lithium battery exceeds the first probability threshold, fire prevention treatment and early warning of the corresponding stage are performed.

[0042] S401: if the current thermal runaway stage of the lithium battery is in the early stage, start the spray device and upload remote warning information; S402: if the current thermal runaway stage of the lithium battery is in the middle stage, increasing the water spraying amount of the spraying device, adjusting the speed of the fan to the maximum value, and uploading remote warning information; S403: If the current thermal runaway stage of the lithium battery is in the late stage, the sprinkler device is adjusted to a maximum water spray volume, the fire prevention device is activated, and remote warning information is uploaded.

[0043] Specifically, the warning information includes: parking space number, current thermal runaway stage of the lithium battery and its probability, and fire prevention measures.

[0044] In this step, in the early stage of thermal runaway of lithium batteries, the battery temperature gradually rises. When the temperature reaches a certain level, the electrolyte in the battery may begin to decompose, and a small amount of smoke may be observed, which is a sign of gas release inside the battery. Therefore, in this stage, the main method of cooling is to use a spray device. Since automotive lithium batteries are usually installed at the bottom of electric vehicles, the spray device needs to be installed on the ground at the rear of the parking space, and the lithium batteries need to be sprayed with water from the rear to cool them down, and early warning information should be used to promptly notify staff and car owners for processing.

[0045] In the middle stage of thermal runaway of lithium batteries, as heat continues to accumulate, the battery temperature rises rapidly, and the internal structure of the battery is affected by the high temperature and may begin to be damaged, such as the melting of the diaphragm, which will produce obvious smoke and gas emissions. Therefore, in this stage, the main thing is to increase the water spray volume of the spray device, and at the same time, quickly discharge smoke and other gases through the fresh air system, and promptly notify the staff and car owners through early warning information for processing.

[0046] In the later stage of thermal runaway of lithium batteries, the battery may undergo violent chemical reactions, releasing a large amount of heat and gas, and the battery may catch fire or even explode, accompanied by open flames and a large amount of thick smoke. Therefore, the maximum spraying measures are taken at this stage, and the fireproof roller shutters are lowered to prevent the burning flames from affecting the surrounding parking spaces, and the staff and car owners are notified in time through early warning information for handling.

[0047] The stage prediction model can accurately identify and predict the various stages and probabilities of thermal runaway of lithium batteries, so that when the system detects initial abnormalities, it can quickly issue an early warning and prompt the implementation of appropriate countermeasures.

[0048] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0049] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0050] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0051] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0052] It should be noted that in the claims, any reference signs placed between brackets shall not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claim. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention may be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third etc. does not indicate any order. These words may be interpreted as names.

[0053] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0054] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0055] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0056] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

Claims

1. A lithium battery thermal runaway early warning method for a parking lot, characterized in that: Based on a lithium battery thermal runaway warning system for a parking lot, the system includes: The infrared imaging sensor is set in the middle of the parking space with the imaging direction facing upwards to monitor the temperature changes of the lithium battery; The smoke sensor is located in the middle of the parking space to monitor the smoke concentration generated by thermal runaway of the lithium battery; A controller, connected to the temperature sensor and the smoke sensor, respectively, for obtaining the temperature and smoke concentration data of the lithium battery, analyzing the current thermal runaway stage of the lithium battery according to the temperature and smoke concentration data, and generating treatment measures and warning information; The method comprises: Acquire a temperature image through the infrared imaging sensor, and calculate the high temperature area ratio and high temperature duration through the temperature image; Acquiring current smoke concentration data and a duration exceeding a first concentration threshold through the smoke sensor; The high-temperature area ratio, high-temperature duration, smoke concentration data, and duration exceeding the first concentration threshold are input into the pre-trained stage prediction model to obtain the current thermal runaway stage of the lithium battery and its probability; If the thermal runaway stage probability of the current lithium battery exceeds a first probability threshold, fire prevention processing and early warning of the corresponding stage are performed.

2. The lithium battery thermal runaway early warning method for a parking lot according to claim 1, characterized in that: The step of obtaining a temperature image by using the infrared imaging sensor and obtaining a high temperature area ratio and a high temperature duration by calculating the temperature image comprises: Acquire a temperature distribution image of the bottom of the vehicle by using the infrared imaging sensor, and pre-process the temperature distribution image to obtain a standard temperature distribution image; Segmenting the standard temperature distribution image into high temperature areas according to a first temperature threshold to obtain high temperature areas; Calculating the total number of pixels in the standard distribution image and the number of high-temperature pixels in the high-temperature area, and calculating the high-temperature area ratio according to the total number of pixels and the number of high-temperature pixels; The number of frames of the standard distribution image with the same high temperature area ratio is calculated, and the high temperature duration is calculated according to the number of frames and the frame interval.

3. A lithium battery thermal runaway early warning method for a parking lot according to claim 2, characterized in that: The high temperature area segmentation of the standard temperature distribution image according to the first temperature threshold to obtain the high temperature area includes: Acquire each frame of the standard temperature distribution image, and apply the first temperature threshold to each frame of the standard temperature distribution image; Pixels exceeding the first temperature threshold are marked as 1, and pixels not exceeding the first temperature threshold are marked as 0, thereby obtaining a high temperature area.

4. A lithium battery thermal runaway early warning method for a parking lot according to claim 2, characterized in that: The calculation formula for the high temperature area ratio is: 。 5. The lithium battery thermal runaway early warning method for a parking lot according to claim 1, characterized in that: The calculation formula for the high temperature time is: 。 6. The lithium battery thermal runaway early warning method for a parking lot according to claim 1, characterized in that: The stage prediction model is trained through the following steps: Collect data on the percentage of high-temperature area, duration of high temperature, smoke density, and duration of exceeding the first concentration threshold, divide the percentage of high-temperature area, duration of high temperature, smoke density, and duration of exceeding the first concentration threshold into several time series samples, calibrate the thermal runaway stage and its probability of each time series sample, and form a stage prediction sample training set; The stage prediction model is constructed by a neural network model, and the stage prediction model is trained by a stage prediction sample training set to obtain the parameters of the stage prediction model.

7. The lithium battery thermal runaway early warning method for a parking lot according to claim 1, characterized in that: The controller is remotely connected to the fan of the parking lot fresh air system for adjusting the wind speed according to the current thermal runaway stage of the lithium battery; The controller is remotely connected to a spray device, which is disposed on the ground behind the parking space and is used to spray and extinguish fire according to the thermal runaway stage of the lithium battery. The controller is remotely connected to a fire protection device, which is arranged above the parking space and is used to prevent fire according to the thermal runaway stage of the current lithium battery.

8. The lithium battery thermal runaway early warning method for a parking lot according to claim 7, characterized in that: The fire prevention device comprises: a plurality of fireproof rolling curtains, which are respectively arranged between adjacent parking spaces and are used to isolate the flames of the adjacent parking spaces.

9. The lithium battery thermal runaway early warning method for a parking lot according to claim 7, characterized in that: The fire prevention treatment and early warning at the corresponding stage include: If the current thermal runaway stage of the lithium battery is in the early stage, the spray device is started and remote warning information is uploaded; If the current thermal runaway stage of the lithium battery is in the middle stage, the water spraying amount of the spraying device is increased, the speed of the fan is adjusted to the maximum value, and the remote warning information is uploaded; If the current thermal runaway stage of the lithium battery is in the late stage, the sprinkler device is adjusted to the maximum water spray volume and the fire prevention device is activated, and the remote warning information is uploaded.

10. The lithium battery thermal runaway early warning method for a parking lot according to claim 1, characterized in that: The warning information includes: parking space number, current thermal runaway stage of the lithium battery and its probability, and fire prevention measures.

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