Battery pack thermal runaway early warning method and system

Abstract

The invention discloses a battery pack thermal runaway early warning method and system, and relates to the technical field of lithium battery thermal runaway safety early warning. Comprising the following steps: acquiring an air pressure value, a CO value and a smoke value of a lithium ion battery pack in a set period, and taking the air pressure value, the CO value and the smoke value of the lithium ion battery pack at a single moment as data parameters; summarizing all data parameters to obtain a parameter matrix, and determining a variability index through an entropy weight method; determining a fusion data information score based on the variability index, and determining an air pressure value parameter, a CO parameter and a smoke parameter according to the fusion data information score; and comparing the fused data information score, the air pressure value parameter, the CO parameter and the smoke parameter with set thresholds respectively, judging the thermal runaway progress stage of the lithium ion battery pack according to a comparison result, and performing early warning according to a judgment result. According to the invention, the battery pack can be monitored in real time, so that workers can timely and fully know the thermal runaway progress stage of the battery, and the accuracy is high.

Description

Technical Field

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

[0002] In recent years, lithium-ion batteries have been widely used in emerging fields such as electric vehicles, drones, energy storage, etc. due to their advantages such as high energy density, high efficiency, low self-discharge rate and long life. However, they also bring a series of fire safety issues, especially thermal runaway accidents of batteries, which may cause fires or explosions, resulting in serious property losses and casualties.

[0003] In the prior art, the thermal runaway warning system of lithium-ion batteries first collects various operating parameters of the battery, such as temperature, voltage, current, etc., in real time through various sensors installed on the single cells in the battery pack. The collected data will be transmitted to the data processing unit of the system, and according to the preset algorithms and models, it is determined whether the battery is in a normal working state or there is a risk of thermal runaway. If abnormalities are detected in parameters such as the temperature, voltage or current of the battery, and these abnormalities meet the warning rules for thermal runaway (such as temperature exceeding the set threshold, abnormal voltage fluctuations, etc.), the system will consider that the battery is at risk of thermal runaway. Once it is determined that the battery is at risk of thermal runaway, the system will immediately send a warning message to the user through an alarm, display or other communication methods, reminding the user to take corresponding measures, such as stopping charging, discharging or performing emergency treatment.

[0004] The defects of the above-mentioned prior art are: in the process of judging thermal runaway, the data processing unit of the early warning system determines whether thermal runaway occurs by comparing a single category of parameters with their respective set values. It cannot accurately grasp the progress stage of thermal runaway, and is prone to inconsistent parameter comparison results, which leads to misjudgment of the early warning system and reduces the accuracy of thermal runaway warning. Summary of the invention

[0005] Based on this, it is necessary to provide a battery pack thermal runaway warning method and system to address the above technical issues.

[0006] An embodiment of the present invention provides a battery pack thermal runaway warning method, comprising:

[0007] Obtain the air pressure value, CO value and smoke value of the lithium-ion battery pack within a set period, and use the air pressure value, CO value and smoke value of the lithium-ion battery pack at a single moment as data parameters;

[0008] All data parameters are summarized to obtain a parameter matrix X that characterizes the gas parameter set of the lithium-ion battery pack, and the variability index used to describe the discrete degree of the parameter matrix X is determined by the entropy weight method;

[0009] Based on the variability index, the fusion data information score representing the gas parameter fusion result of the lithium-ion battery pack at a single moment is determined, and the air pressure value parameter, CO parameter and smoke parameter representing the weight of each data parameter at the corresponding moment are determined according to the fusion data information score;

[0010] The fusion data information score, air pressure value parameters, CO parameters and smoke parameters are compared with the set thresholds respectively, and the thermal runaway progress stage of the lithium-ion battery pack is judged according to the comparison results, and an early warning is issued according to the judgment result of the thermal runaway progress stage.

[0011] Optionally, a parameter matrix X characterizing a set of gas parameters of a lithium-ion battery pack is obtained, and its expression is:

[0012]

[0013] Among them, m is the data type, and n is the number of data obtained in the set period.

[0014] Optionally, when all data parameters are summarized, each data parameter is subjected to standardized preprocessing, which specifically includes:

[0015] The data parameters in the parameter matrix X are standardized by the range change method, and the calculation formula is:

[0016]

[0017] The result of the normalization process is:

[0018]

[0019] Among them, i is the i-th data type, j is the value of the j-th data in the set period, and y ij Represents the value of the jth data under the i-th data type (i=1,2,…,m; j=1,2,…n).

[0020] Optionally, the variability index used to describe the discrete degree of the parameter matrix X is determined by the entropy weight method, and its calculation formula is:

[0021]

[0022] Where m is the data type, n is the number of data acquired within the set period, i is the i-th data type, j is the value of the j-th data within the set period, and w ij is the proportion of the jth collected value of the i-th data type, y ij Represents the value of the jth data under the i-th data type.

[0023] Optionally, the air pressure value parameter, CO parameter and smoke parameter representing the weight of each data parameter at the corresponding moment are determined according to the fusion data information score, and the calculation formula is:

[0024]

[0025] Among them, W j Set the fusion data information score of different types of parameters collected at each moment in the collection cycle during thermal runaway, S i is the weight of different types of parameters collected; g j is the redundancy; y ij is the value of the jth data under the i-th data type after normalization.

[0026] Optionally, the redundancy g j The calculation formula is:

[0027] gj=1-ej

[0028]

[0029] Among them, i is the i-th data type, j is the value of the j-th data obtained within the set period, and e j is information entropy, g j is the redundancy, w ij is the proportion of the jth collected value of the ith data type, and k is a constant.

[0030] The embodiment of the present invention further provides a battery pack thermal runaway warning system, comprising:

[0031] A monitoring unit, including an air pressure sensor, a smoke sensor, a CO sensor and a monitoring host, is used to determine the thermal runaway progress stage of the lithium-ion battery pack based on the collected data;

[0032] An alarm unit, including a display screen for displaying an alarm digital signal and an alarm for issuing an alarm message, and used for issuing an alarm according to the determination result of the thermal runaway progress stage of the monitoring unit;

[0033] The pressure relief explosion-proof unit includes a battery box for accommodating batteries, a fan, a fire extinguisher and an exhaust hole, and is used for performing pressure relief processing according to the alarm result of the alarm unit.

[0034] Optionally, in the monitoring unit, when the safety valve is opened, the data fusion parameter in the battery pack is a first-level preset value, when thermal runaway occurs, the data fusion parameter in the battery pack is a second-level preset value, and when a single battery thermal runaway spreads to adjacent batteries or causes a large-scale explosion due to other reasons, the data fusion parameter in the battery pack is a third-level preset value.

[0035] Optionally, the alarm unit outputs digital signal A, digital signal B and digital signal C;

[0036] Digital signal A represents that the collected fusion data parameter exceeds the first-level preset value, and the battery safety valve is opened;

[0037] Digital signal B represents that the collected fusion data parameter exceeds the secondary preset value and the battery has thermal runaway;

[0038] Digital signal C represents that the collected fusion data parameters exceed the third-level preset value, and thermal runaway spreads to adjacent batteries, causing large-scale explosion.

[0039] Optionally, the pressure relief explosion-proof unit specifically includes:

[0040] The battery box has two layers. The inner box is used to accommodate batteries, and an exhaust hole is provided on the upper part of the inner box. The outer box has two openings. The upper opening is the outer exhaust port for discharging the gas sprayed by the battery explosion, and the lower opening is connected to the fire extinguisher.

[0041] Compared with the prior art, the above-mentioned battery pack thermal runaway warning method and system provided by the embodiment of the present invention has the following beneficial effects:

[0042] In the prior art, whether thermal runaway occurs is determined by comparing a single category of parameters with their respective set values, which easily leads to inconsistent parameter comparison results, causing misjudgment of the warning system and reducing the accuracy of thermal runaway warning.

[0043] The present invention determines the fused data information score of the lithium-ion battery pack at different times based on the variability index, and determines the weight of each data parameter at different times according to the fused data information score, to obtain the air pressure value parameter, CO parameter and smoke parameter; takes the fused information data score as a precondition, and uses the air pressure value parameter, CO parameter and smoke parameter as auxiliary criteria to perform graded warning for thermal runaway of the battery pack, and keeps the warning time within the time period of the lithium-ion battery pack, which can monitor the battery pack in real time, so that the staff can fully and timely understand the progress stage of the battery thermal runaway, with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A diagram of air pressure variation of a battery pack thermal runaway warning method provided in an embodiment;

[0045] Figure 2 A schematic structural diagram of a battery pack thermal runaway warning method provided in an embodiment;

[0046] Figure 3 A schematic diagram of a process flow of a battery pack thermal runaway warning system provided in an embodiment;

[0047] Figure 2In: 1. Air pressure sensor; 2. Smoke sensor; 3. CO sensor; 4. Monitoring host; 5. Display screen; 6. Alarm; 7. Battery box; 8. Fan; 9. Fire extinguisher; 10. Exhaust hole; 11. Battery module. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0049] In one embodiment, a battery pack thermal runaway warning method is provided, the method comprising:

[0050] 1. Obtain the air pressure value, CO value and smoke value of the lithium-ion battery pack within a set period, and use the air pressure value, CO value and smoke value of the lithium-ion battery pack at a single moment as data parameters.

[0051] like Figure 1 As shown, the set cycle refers to the entire cycle consisting of three stages: safety valve opening, thermal runaway of the lithium-ion battery pack, and thermal runaway propagation.

[0052] 2. All data parameters are summarized to obtain the parameter matrix X that characterizes the gas parameter set of the lithium-ion battery pack, and the variability index used to describe the discrete degree of the parameter matrix X is determined by the entropy weight method.

[0053] 3. Based on the variability index, the fusion data information score that characterizes the gas parameter fusion result of the lithium-ion battery pack at a single moment is determined, and the pressure value parameter, CO parameter and smoke parameter that characterize the weight of each data parameter at the corresponding moment are determined according to the fusion data information score.

[0054] 4. Compare the fusion data information score, air pressure value parameter, CO parameter and smoke parameter with the set threshold value respectively, and judge the thermal runaway progress stage of the lithium-ion battery pack according to the comparison results, and issue an early warning according to the judgment result of the thermal runaway progress stage.

[0055] In one embodiment, a battery pack thermal runaway warning system is provided, such as Figure 2 As shown, the system includes:

[0056] The monitoring unit includes an air pressure sensor 1, a smoke sensor 2, a CO sensor 3 and a monitoring host 4, and is used to determine the thermal runaway progress stage of the lithium-ion battery pack based on the collected data.

[0057] The alarm unit includes a display screen 5 for displaying an alarm digital signal and an alarm 6 for sending out an alarm message, and is used to give an alarm according to the judgment result of the progress stage of the thermal runaway of the monitoring unit.

[0058] The pressure relief explosion-proof unit comprises a battery box 7 for accommodating batteries, a fan 8, a fire extinguisher 9 and an exhaust hole 10, and is used for performing pressure relief processing according to the alarm result of the alarm unit.

[0059] The monitoring unit described in the embodiment of the present invention includes an air pressure monitoring sensor for monitoring the air pressure in the battery pack as the main monitoring module, a smoke sensor 2 and a CO sensor 3 as auxiliary monitoring modules, and a monitoring host 4 as a storage control device. The air pressure value in the battery pack is obtained by using the air pressure sensor 1. In order to obtain a complete air pressure change waveform, the acquisition frequency is preferably greater than 2Hz, and three levels of air pressure thresholds are set according to the air pressure when the battery safety valve is opened, thermal runaway, and a single battery thermal runaway spreads to adjacent batteries or a large-scale explosion is caused by other reasons. In order to improve the reliability of the explosion monitoring and early warning in the battery pack, the smoke sensor 2 and the CO sensor 3 are used as auxiliary monitoring modules. Based on the entropy weight method, the acquisition parameters of the three sensors are fused within the set acquisition cycle, and the CO and smoke parameter thresholds are set at the same time. Finally, the warning level is determined based on the data fusion result and the comparison result between the collected CO and smoke and the preset value.

[0060] The warning is mainly based on the air pressure value, supplemented by CO and smoke values. The multi-level monitoring and warning threshold of air pressure is set in the control system. The threshold is determined based on the parameter information collected after the battery thermal runaway test, and the preset values ​​are different for lithium-ion batteries of different types and capacities.

[0061] As shown in the following formula, the air pressure value, CO value and smoke value of the lithium-ion battery pack within the set period are obtained, and the air pressure value, CO value and smoke value of the lithium-ion battery pack at a single moment are used as data parameters. All data parameters are summarized to obtain the parameter matrix X that characterizes the gas parameter set of the lithium-ion battery pack. Among them, m is the type of data collected by the sensor, and n is the number of data collected in the collection period.

[0062]

[0063] Since the measurement units of various data parameters are not uniform, each data parameter is pre-processed for standardization when all data parameters are summarized. Including:

[0064] The data parameters in the parameter matrix X are standardized by the range change method, and the calculation formula is:

[0065]

[0066] The result of the normalization process is:

[0067]

[0068] Among them, i is the i-th data type, and j is the value of the j-th data obtained in the set period. Then the weight w of each data parameter at different times in the set period can be calculated ij .

[0069]

[0070] Finally, the fusion data information score W of different types of parameters collected at each moment in the set collection period during thermal runaway is obtained. j and are the weights of different types of parameters collected S i . g j is the redundancy; y ij is the value of the jth data under the i-th data type after the above standardization processing.

[0071]

[0072] Among them, e j is the entropy value of the jth data parameter, i.e., information entropy; g j is the coefficient of variation of the jth data parameter, i.e., redundancy, which can be calculated according to the following formula:

[0073] gj=1-ej

[0074]

[0075] w ij is the proportion of the jth collected value of the i-th data type; is a constant, where k>0, e j ≥0.

[0076] When the safety valve is open, the data fusion parameter in the battery pack is the first-level preset value. When thermal runaway occurs, the data fusion parameter in the battery pack is the second-level preset value. When a single battery thermal runaway spreads to adjacent batteries or causes a large-scale explosion due to other reasons, the data fusion parameter in the battery pack is the third-level preset value. By setting these three fusion data thresholds, the progress stage of thermal runaway in the lithium-ion battery pack can be judged. In addition, in order to improve the accuracy of the early warning, the preset values ​​of CO and smoke are set in the host. The early warning level is judged according to the comparison results of the data fusion parameters and the collected CO and smoke with the preset values, and the corresponding early warning and alarm signals are issued.

[0077] A fan 8 is provided in the battery pack to cool the battery when it is working normally, and to stir the air in the battery pack so that the smoke sensor 2 and the CO sensor 3 can respond quickly in abnormal situations. The acquisition cycle of the air pressure sensor 1 is T, the acquisition cycle of the smoke sensor 2 and the CO sensor 3 is t, and the acquisition cycle of the fusion data information is also t. Under normal circumstances, the host controls the air pressure sensor 1 to monitor the air pressure in the battery pack in real time online, while the smoke sensor 2 and the CO sensor 3 are offline.

[0078] The alarm unit described in the embodiment of the present invention includes a display screen 5 for displaying an alarm digital signal and an alarm 6 for issuing an alarm message. The host controls the output of digital signals A, B and C according to the preset values ​​of the fusion data. Digital signal A represents that the collected fusion data parameter exceeds the first-level preset value, and the battery safety valve is opened; digital signal B represents that the collected fusion data parameter exceeds the second-level preset value, and the battery has thermal runaway; digital signal C represents that the collected fusion data parameter exceeds the third-level preset value, and the thermal runaway spreads to adjacent batteries or causes a large-scale explosion due to other reasons.

[0079] When the air pressure sensor 1 detects that the air pressure in the battery pack exceeds the preset value within a certain T period, the host controls the smoke sensor 2 and the CO sensor 3 to immediately collect the smoke and CO parameters in the battery pack online. The host judges and controls the display of the output digital signal A, B or C on the display screen 5 according to the preset value of the fusion data. At the same time, it is judged whether the smoke or CO parameters in the battery pack collected within a t period exceed the set threshold. If the host judges that the parameter exceeds the set threshold, the output digital signal "0" is displayed on the display screen 5, otherwise the output signal "1" is displayed. If the signal "0" is displayed on the display screen 5, it means that the battery in the battery pack has exploded. If the signal "1" is displayed, it is judged whether the fusion data collected within the t+1 period still exceeds the preset value, and at the same time, it is judged whether the parameters collected by the smoke sensor 2 and the CO sensor 3 exceed the threshold. If the fusion data collected within three periods exceeds the preset value but the smoke and CO still do not exceed the threshold, it is checked whether the air pressure sensor 1 has a fault and needs to be repaired or replaced. The host controls the output display of the digital signal "0101" on the display screen 5.

[0080] The embodiment of the present invention divides the alarm unit into four levels according to the digital signal outputted by the display screen 5. When the host displays that the collected fusion data exceeds the first-level preset value and determines that a burst has occurred in the battery pack, the output signal is "A, 0", and the alarm component issues an alarm signal; when the host displays that the collected fusion data exceeds the second-level preset value and determines that a burst has occurred in the battery pack, the output signal is "B, 0", and the alarm component issues a second alarm signal; when the host displays that the collected fusion data exceeds the third-level preset value and determines that a burst has occurred in the battery pack, the output signal is "C, 0", and the alarm component issues a third alarm signal; in other cases, such as when the host displays that the collected fusion data exceeds the preset value but does not determine that a burst has occurred in the battery pack, it may be that the sensor fails, the output signal is "A / B / C, 0101", and the alarm component issues a fourth-level alarm signal. At this time, manual judgment is required as to whether a battery safety accident has occurred.

[0081] The pressure relief explosion-proof unit described in the embodiment of the present invention includes a battery box 7 for accommodating batteries, a fan 8, a fire extinguisher 9 and an exhaust hole 10. The battery box 7 of the present invention has two layers, the inner box is used to accommodate batteries, and the upper part of the inner box is provided with an exhaust hole 10. The outer box is provided with two openings, the upper opening is an outer exhaust port for discharging the gas sprayed out by the battery explosion, and the lower opening is connected to the fire extinguisher 9. Once it is determined that an explosion has occurred in the battery pack, the controller controls the exhaust hole 10 and the fire extinguisher 9 to open. Under the dual action of the fan 8 in the inner layer of the battery box 7 and the external fire extinguisher 9, the sprayed gas can be quickly discharged to the outside of the battery pack, thereby achieving pressure relief and effectively preventing explosion. At the same time, the fire extinguisher 9 can also cool the battery pack to delay thermal runaway.

[0082] like Figure 3 As shown, exemplarily, S1: the battery pack is normal, the air pressure sensor 1 monitors the air pressure in the battery pack in real time online, the smoke sensor 2 and the CO sensor 3 are in an offline state, and the controller in the battery module 11 stores the collected air pressure value and determines whether the air pressure value in the battery pack collected in each collection period T exceeds the preset value;

[0083] S2: In the Tth cycle collected by the air pressure sensor 1, if the air pressure value is less than the preset value, go to S3; if the air pressure value is greater than or equal to the first-level preset value, go to S4; if the air pressure value is greater than or equal to the second-level preset value, go to S5; if the air pressure value is greater than or equal to the third-level preset value, go to S6;

[0084] S3: The controller continuously stores and collects the air pressure value;

[0085] S4: The controller controls smoke sensor 2 and CO sensor 3 to start collecting smoke parameters and CO parameters. The collection period is t. Each parameter information collected by different sensors is regarded as a data parameter. Each data parameter contains the parameter value within the t period. The fusion data information score at different times in the collection period is calculated based on the entropy weight method. The fusion data information score is used as the fusion data parameter. If the fusion data ≤ the set fusion data threshold and the CO parameter and the smoke parameter ≤ the set threshold, go to S7; if the fusion data ≥ the set fusion data threshold and the CO parameter and the smoke parameter ≥ the set threshold, go to S8;

[0086] S5: The controller controls smoke sensor 2 and CO sensor 3 to start collecting smoke parameters and CO parameters. The collection period is t. Each parameter information collected by different sensors is regarded as a data parameter. Each data parameter contains the parameter value within the t period. The fusion data information score at different times in the collection period is calculated based on the entropy weight method. The fusion data information score is used as the fusion data parameter. If the fusion data ≤ the set fusion data threshold and the CO parameter and the smoke parameter ≤ the set threshold, go to S7; if the fusion data ≥ the set fusion data threshold and the CO parameter and the smoke parameter ≥ the set threshold, go to S9;

[0087] S6: The controller controls smoke sensor 2 and CO sensor 3 to start collecting smoke parameters and CO parameters. The collection period is t. Each parameter information collected by different sensors is regarded as a data parameter. Each data parameter contains the parameter value within the t period. The fusion data information score at different times in the collection period is calculated based on the entropy weight method. The fusion data information score is used as the fusion data parameter. If the fusion data ≤ the set fusion data threshold and the CO parameter and the smoke parameter ≤ the set threshold, go to S7; if the fusion data ≥ the set fusion data threshold and the CO parameter and the smoke parameter ≥ the set threshold, go to S10;

[0088] S7: Determine whether the fusion data collected within the t+1 period still exceeds the preset value, and at the same time determine whether the data collected by the smoke and CO sensor 3 exceeds the threshold value. If the fusion data collected within three periods still exceeds the preset value but the smoke and CO still do not exceed the threshold value, the controller outputs a signal "A, 0101", "B, 0101" or "C, 0101", and the alarm component sends a fourth-level alarm signal. At this time, it is necessary to promptly check whether the air pressure sensor 1 is faulty and needs to be repaired or replaced;

[0089] S8: Output signal "A, 0", the alarm component sends out a first-level alarm signal, and then goes to S11;

[0090] S9: Output signal "B, 0", the alarm component sends out a secondary alarm signal, and then goes to S11;

[0091] S10: Output signal "C, 0", the alarm component sends out a level 3 alarm signal, and then goes to S11;

[0092] S11: The controller controls the explosion-proof exhaust holes 10 in the inner layer of the battery box 7 and the fire extinguisher 9 outside the battery box 7 to open, discharge the ejected gas out of the battery pack, achieve pressure relief to prevent explosion, and cool the battery pack to delay thermal runaway.

[0093] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A battery pack thermal runaway early warning method, characterized in that: include: Obtain the air pressure value, CO value and smoke value of the lithium-ion battery pack within a set period, and use the air pressure value, CO value and smoke value of the lithium-ion battery pack at a single moment as data parameters; All data parameters are summarized to obtain a parameter matrix X that characterizes the gas parameter set of the lithium-ion battery pack, and the variability index used to describe the discrete degree of the parameter matrix X is determined by the entropy weight method; Based on the variability index, the fusion data information score representing the gas parameter fusion result of the lithium-ion battery pack at a single moment is determined, and the air pressure value parameter, CO parameter and smoke parameter representing the weight of each data parameter at the corresponding moment are determined according to the fusion data information score; The fusion data information score, air pressure value parameters, CO parameters and smoke parameters are compared with the set thresholds respectively, and the thermal runaway progress stage of the lithium-ion battery pack is judged according to the comparison results, and an early warning is issued according to the judgment result of the thermal runaway progress stage.

2. A battery pack thermal runaway warning method as claimed in claim 1, characterized in that: The parameter matrix X obtained to characterize the gas parameter set of the lithium-ion battery pack is expressed as follows: Among them, m is the data type, and n is the number of data obtained in the set period.

3. A battery pack thermal runaway warning method as claimed in claim 2, characterized in that: When all the data parameters are summarized, each data parameter is subjected to standardized preprocessing, which specifically includes: The data parameters in the parameter matrix X are standardized by the range change method, and the calculation formula is: The result of the normalization process is: Among them, i is the i-th data type, j is the value of the j-th data in the set period, and y ij Represents the value of the jth data under the i-th data type (i=1,2,…,m; j=1,2,…n).

4. A battery pack thermal runaway warning method as claimed in claim 1, characterized in that: The variability index used to describe the discrete degree of the parameter matrix X is determined by the entropy weight method, and its calculation formula is: Where m is the data type, n is the number of data acquired within the set period, i is the i-th data type, j is the value of the j-th data within the set period, and w ij is the proportion of the jth collected value of the i-th data type, y ij Represents the value of the jth data under the i-th data type.

5. A battery pack thermal runaway warning method as claimed in claim 4, characterized in that: The calculation formula for determining the air pressure value parameter, CO parameter and smoke parameter representing the weight of each data parameter at the corresponding moment according to the fusion data information score is: Among them, W j Set the fusion data information score of different types of parameters collected at each moment in the collection cycle during thermal runaway, S i is the weight of different types of parameters collected; g j is the redundancy; y ij is the value of the jth data under the i-th data type after normalization.

6. A battery pack thermal runaway warning method as claimed in claim 5, characterized in that: The redundancy g j The calculation formula is: gj=1-ej Among them, i is the i-th data type, j is the value of the j-th data obtained within the set period, and e j is information entropy, g j is the redundancy, w ij is the proportion of the jth collected value of the ith data type, and k is a constant.

7. A battery pack thermal runaway warning system based on the battery pack thermal runaway warning method according to any one of claims 1 to 6, characterized in that: include: The monitoring unit comprises an air pressure sensor (1), a smoke sensor (2), a CO sensor (3) and a monitoring host (4), and is used to determine the thermal runaway progress stage of the lithium-ion battery pack based on the collected data; An alarm unit, comprising a display screen (5) for displaying an alarm digital signal and an alarm (6) for issuing an alarm message, and used for issuing an alarm according to a determination result of the thermal runaway progress stage of the monitoring unit; The pressure relief explosion-proof unit comprises a battery box (7) for accommodating batteries, a fan (8), a fire extinguisher (9) and an exhaust hole (10), and is used for performing pressure relief processing according to the alarm result of the alarm unit.

8. A battery pack thermal runaway warning system as claimed in claim 7, characterized in that: In the monitoring unit, when the safety valve is opened, the data fusion parameter in the battery pack is a first-level preset value, when thermal runaway occurs, the data fusion parameter in the battery pack is a second-level preset value, and when a single battery thermal runaway spreads to adjacent batteries or causes a large-scale explosion due to other reasons, the data fusion parameter in the battery pack is a third-level preset value.

9. A battery pack thermal runaway warning system as claimed in claim 7, characterized in that: The alarm unit outputs digital signal A, digital signal B and digital signal C; Digital signal A represents that the collected fusion data parameter exceeds the first-level preset value, and the battery safety valve is opened; Digital signal B represents that the collected fusion data parameter exceeds the secondary preset value and the battery has thermal runaway; Digital signal C represents that the collected fusion data parameters exceed the third-level preset value, and thermal runaway spreads to adjacent batteries, causing large-scale explosion.

10. A battery pack thermal runaway warning system as claimed in claim 7, characterized in that: The pressure relief explosion-proof unit specifically comprises: The battery box (7) has two layers, the inner box is used to accommodate batteries, and the upper part of the inner box is provided with an exhaust hole (10); the outer box is provided with two openings, the upper opening is an outer exhaust port for discharging gas ejected by the battery explosion, and the lower opening is connected to a fire extinguisher (9).

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