Method for monitoring temperature abnormity of battery pack of new energy automobile

Abstract

The invention relates to a method for monitoring temperature abnormity of a new energy automobile battery pack, which comprises the following steps of: (1) acquiring a chassis surface temperature Tw and an environment temperature T0 in a new energy automobile battery pack area, if Tw-T0 is greater than 0.5 DEG C, executing a step (2), otherwise, stopping executing; (2) acquiring a new energy automobile battery pack area chassis surface temperature change B = Tw2-Tw1 within a period of time t1; if B is greater than 0, executing the step (3), and if B is less than 0, stopping executing; (3) the internal temperature rise TN = K * B + T of the new energy automobile battery pack after t1 is obtained through calculation, K is a proportionality coefficient, and T is a temperature correction value; and (4) when the internal temperature rise TN exceeds the first safety range, determining that the temperature of the new energy automobile battery pack is abnormal. The temperature change in the battery can be calculated by identifying the change of the surface temperature of the chassis in the battery pack area of the new energy automobile, and thermal runaway early warning is given out in time.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and in particular to a method for monitoring abnormal temperature of a battery pack of a new energy vehicle. Background Art

[0002] In the field of new energy vehicles, batteries are core components, and the safety of their battery systems is directly related to the safety of vehicles and passengers. However, there is currently a significant problem: when new energy vehicle batteries are at risk of thermal runaway, the early warning mechanism is not perfect.

[0003] Abnormal increase in battery temperature is an important precursor to battery thermal runaway. Thermal runaway will not only damage battery performance and significantly shorten its service life, but may also cause serious accidents such as fire, posing a major threat to the safety of life and property of the vehicle and passengers. Existing monitoring methods are difficult to accurately identify small changes in battery temperature, and cannot timely and accurately predict the risk of thermal runaway, making it difficult to meet the growing safety needs of new energy vehicles. Therefore, it is urgent to develop a method that can effectively monitor the sudden rise in battery temperature and accurately predict the risk of thermal runaway when the vehicle is stationary. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a method for monitoring the abnormal temperature rise of the battery pack of a new energy vehicle, aiming to monitor the battery temperature rise through an innovative algorithm to ensure the safe operation of the new energy vehicle.

[0005] In order to achieve the purpose of the present invention, this application provides the following technical solutions.

[0006] In a first aspect, the present application provides a method for monitoring abnormal temperature of a new energy vehicle battery pack, characterized in that the method comprises the following steps: (1) Obtain the chassis surface temperature T of the battery pack area of ​​the new energy vehicle w And the ambient temperature T 0 , if T w -T 0 >0.5℃, execute step (2), otherwise stop. When the chassis surface temperature in the battery pack area of ​​the new energy vehicle is close to the ambient temperature, it indicates that the battery system is in thermal equilibrium. At this time, the heat generated inside the battery is low or no significant heat accumulation occurs. Its autonomous heat dissipation performance has fully met the heat dissipation requirements, and heat transfer is not enough to cause the chassis surface temperature in the battery pack area of ​​the new energy vehicle to rise. Under this condition, there will be no safety hazard, so there is no need to trigger the thermal runaway warning mechanism.

[0007] (2) Get a period of time t 1 The temperature change of the chassis surface in the battery pack area of ​​the new energy vehicle is B = T w2- T w1 ; where T w1 is the initial surface temperature of the chassis in the new energy vehicle battery pack area during this period, and T w2 is the surface temperature of the chassis in the new energy vehicle battery pack area at the end of this period, and (T 0 + 0.5) °C is used as the initial value; if B > 0, then execute step (3), if B < 0, then stop execution. When the surface temperature of the chassis in the new energy vehicle battery pack area is relatively high, there are two possibilities: The first is that heat accumulation occurs due to battery failure, and through the way of heat conduction, it causes the rise of the surface temperature of the chassis in the new energy vehicle battery pack area, resulting in the surface temperature of the battery being much higher than the ambient temperature (i.e., > 0.5 °C). The second is that the vehicle has just stopped, and the surface temperature of the chassis in the new energy vehicle battery pack area itself is at a high value and requires a heat dissipation process. However, in this case, the surface temperature of the battery will gradually decrease, and no danger will occur at this time, so no warning is required.

[0008] (3) Calculate the internal temperature rise △T 1 of the new energy vehicle battery pack after t N = K × B + △T, where K is the proportionality coefficient and △T is the temperature correction value; in this application, by monitoring the surface temperature rise of the chassis in the new energy vehicle battery pack area, the internal temperature rise of the battery is inferred. Once the internal temperature rise of the battery is abnormal, an alarm can be issued in time to notify the vehicle owner and the emergency department, greatly shortening the response time. Thus, the time efficiency of event handling is effectively improved, the safety of the vehicle and the surrounding environment is guaranteed, the overall safety management level is enhanced, and the economic and personal losses caused by fire are minimized to the greatest extent.

[0009] (4) Make a determination. When the internal temperature rise △T N exceeds the safety range, it is determined that the temperature of the new energy vehicle battery pack is abnormal. The criteria for judging temperature abnormality in this application are as follows: it depends on whether the calculated internal temperature rise of the battery exceeds 10 °C within t 1 minutes. For example, by monitoring the surface temperature rise of the chassis in the new energy vehicle battery pack area within 5 minutes of the battery, and after calculation, then infer whether there is △T N > 10 °C in these 5 groups of calculation results from 0 - 1 minute, from 0 - 2 minutes, from 0 - 3 minutes, from 0 - 4 minutes, and from 0 - 5 minutes. Once it appears, it is determined to be abnormal.

[0010] In the present invention, the internal temperature rise rate of the battery can be inferred by monitoring the surface temperature of the chassis in the new energy vehicle battery pack area, and finally the purpose of monitoring whether the battery has temperature abnormality is achieved.

[0011] In an embodiment of the first aspect, when 0 ≤ B ≤ 0.4, K = 5.5 and △T = -0.2; When 0.4 < B < 1, K = 5 and △T = 0; When 1 ≤ B < 2, K = 4.5 and △T = 0.5; When B ≥ 2, K = 4.5 and △T = 2.

[0012] In an embodiment of the first aspect, the t 1 is selected from a fixed value within 1 to 10 minutes.

[0013] Wherein, the selection of t 1 is determined according to the models of different new energy vehicles. Because for different models of new energy vehicles, the batteries used are different, and for different batteries, due to different factors such as the thickness and material of the outer shell used for the outer shell, and the flow rate of the internal coolant, the rate of heat transfer from the inside to the outside of different batteries is different. Therefore, the time intervals for determining whether there is a sharp rise in the internal temperature of the battery are also different. Through a large number of experiments, the applicant tested the new energy vehicles on the market, that is, tested the relationship between the internal temperature rise of the battery and the temperature rise on the chassis surface of the battery pack area of the new energy vehicle. Through fitting, the optimal t 1 corresponding to this model of vehicle was finally determined. In subsequent actual monitoring, as long as the model of the new energy vehicle is determined, the value of t 1 can be directly retrieved.

[0014] In an embodiment of the first aspect, the internal temperature rise △T N exceeding the first safety range is: within the t 1 time period, from the beginning to the end of the time period, the internal temperature rise △T N > 10°C. This is to judge whether thermal runaway occurs inside the battery by whether the total temperature rise within a certain time is too high.

[0015] In an embodiment of the first aspect, the temperature T w on the chassis surface of the battery pack area of the new energy vehicle is measured by an infrared thermometer, and the infrared thermometer measures once every 1 s, and every t 3 is used as a test cycle. t 3 is a fixed value between 5 and 20 s. The average temperature of each test cycle is T a , and T w is the average temperature of all test cycles within one minute, that is, T w = (T a1 + T a2 + …… + T an ) / n.

[0016] In an embodiment of the first aspect, within the same test cycle, if the difference between adjacent test temperatures exceeds 2°C, the subsequent measurement value is filtered.

[0017] Since an infrared thermometer is used, during the process of measuring the surface temperature of the chassis in the battery pack area of a new energy vehicle, it is possible that debris temporarily blocks between the infrared thermometer and the chassis. At this time, the temperature measured by the infrared thermometer is actually the surface temperature of the debris. Therefore, this test data needs to be excluded.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) By monitoring the surface temperature rise of the chassis in the battery pack area of a new energy vehicle in real time, the present invention can predict the temperature rise inside the battery. Once the temperature rise inside the battery is abnormal, an alarm can be issued in a timely manner to notify the vehicle owner and the emergency department, greatly shortening the response time. Thereby effectively improving the time efficiency of incident handling, ensuring the safety of the vehicle and the surrounding environment, enhancing the overall safety management level, and minimizing the economic and personal losses caused by fires.

[0019] (2) By monitoring the surface temperature rise of the chassis in the battery pack area of a new energy vehicle in real time, the difference between the calculated temperature rise inside the battery and the actual temperature rise inside the battery is within 2°C. The monitoring result is accurate, enabling users to take actions in a timely manner before the risk occurs, effectively avoiding accidents caused by battery thermal runaway, and providing a strong guarantee for the safe operation of new energy vehicles. Specific embodiments

[0020] Unless otherwise defined, the technical terms or scientific terms used in this specification and the claims should have the ordinary meanings understood by those of ordinary skill in the technical field to which the present invention belongs. All numerical values listed herein from the lowest value to the highest value refer to all numerical values obtained by incrementing by one unit between the lowest value and the highest value when the difference between the lowest value and the highest value is more than two units.

[0021] The following will describe the specific embodiments of the present invention. It should be noted that during the specific description of these embodiments, for the sake of concise description, this specification cannot describe all features of the actual embodiments in detail. Without departing from the spirit and scope of the present invention, those skilled in the art can modify and replace the embodiments of the present invention, and the obtained embodiments are also within the protection scope of the present invention.

[0022] The present invention relates to the technical field of new energy vehicles, especially for the thermal management part in the battery pack management system of new energy vehicles, and proposes an innovative algorithm for monitoring the sudden temperature rise inside the battery. The algorithm aims to accurately judge whether there is a risk of battery thermal runaway by monitoring and analyzing the temperature change of the battery at rest in real time, thereby ensuring the safe operation of new energy vehicles.

[0023] On a broader level, the present invention also relates to the field of safety monitoring and early warning technologies for new energy vehicles, providing new ideas and methods for improving the overall safety and reliability of new energy vehicles. Through the present invention, it is possible to achieve real-time monitoring and early warning of the state of the battery pack of new energy vehicles, effectively prevent the occurrence of battery thermal runaway accidents, and provide strong support for the healthy development of the new energy vehicle industry.

[0024] In a specific embodiment, the present application provides a method for monitoring abnormal temperature of the battery pack of a new energy vehicle. This method can accurately identify minute changes in the surface temperature of the chassis in the battery area of the new energy vehicle, thereby calculating the actual temperature change inside the battery, and promptly issuing a thermal runaway early warning. By continuously monitoring the surface temperature data of the chassis in the battery area of the new energy vehicle and combining advanced algorithms, it is possible to effectively predict the risk of battery thermal runaway, providing strong guarantee for the safe operation of new energy vehicles. The application of this algorithm will significantly improve the safety and reliability of new energy vehicles and contribute to the healthy development of the new energy vehicle industry.

[0025] In a specific embodiment, the method includes the following aspects: Data acquisition: Through infrared temperature measurement technology, the surface temperature of the chassis in the battery pack area of the new energy vehicle is collected in a non-contact manner in real time. Raw data is collected once per second, and a statistical period is formed at intervals of several seconds (generally, 10 s is selected as a period, and of course, other values can also be selected, such as a value in the range of 5 - 20 s). Within each statistical period, the system filters out some unstable data and calculates the average value of the remaining data, which serves as the basic data support for analyzing the change trend of the surface temperature of the chassis in the battery pack area of the new energy vehicle during charging or in a stationary state.

[0026] Data analysis: After data acquisition, preprocessing steps are required to effectively filter out dirty data, thereby improving the accuracy and reliability of the data. Then, the collected temperature is analyzed in real time to calculate the rate of change of the temperature inside the battery. The rate of change of the temperature inside the battery is an important basis for judging whether there is an abnormal temperature rise trend in the battery.

[0027] Through minute changes in the surface temperature of the chassis in the battery area of the new energy vehicle, the present application calculates and estimates the change trend of the actual temperature inside the battery through this algorithm, enabling the system to more accurately judge the thermal state inside the battery, thereby early warning potential thermal runaway risks.

[0028] Combined with historical temperature data for analysis to comprehensively evaluate the health status of the battery. Through in-depth mining and statistical analysis of historical data, long-term trends and abnormal patterns in battery temperature changes are identified. Based on these analysis results, the system can formulate targeted maintenance plans for the health status of the battery, including but not limited to regular inspections, cooling system optimization, battery balancing adjustment, etc., to ensure that the battery is always in the best working condition and extend its service life.

[0029] Thermal runaway warning judgment: In the new energy vehicle battery pack safety monitoring system, this application has established a standard range for the normal rate of change of the internal battery temperature. This range covers the temperature change situation from the occurrence of battery anomalies to before thermal runaway. The system will start from the preset monitoring starting point and continuously track the change of the battery temperature to ensure accurate control of the battery status. When the real-time monitored temperature change rate exceeds this preset normal range, the system will immediately determine that the battery has a trend of abnormal temperature rise.

[0030] Based on the rate of change of the battery temperature, an early warning mechanism for the rate of change of temperature can also be scientifically set. The setting of this rate of change of temperature has been verified through a large amount of data and battery performance analysis, aiming to ensure a rapid response when the battery temperature rises abnormally. Once the rate of change of the battery temperature exceeds the preset safety range, the thermal runaway early warning mechanism will be immediately triggered. At the same time, this application also sets a high-temperature threshold alarm, and once the detected temperature exceeds the set threshold, the alarm will also be triggered.

[0031] When the warning is triggered, relevant personnel can be quickly notified so that they can take necessary safety measures in a timely manner, thus effectively avoiding the risks that may be brought by battery thermal runaway. By combining the real-time monitoring of the rate of change of temperature and the high-temperature threshold alarm, the system realizes multi-level and all-round monitoring of the battery safety status. Embodiment

[0032] The embodiments of the present invention will be described in detail below. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments. Embodiment

[0033] Select the chassis system of a new energy vehicle, including a battery pack, a cooling layer, an insulating and shock-absorbing layer, a protective layer, etc. Install a heating device and a temperature sensor inside the battery pack. Among them, the heating device can control the temperature rise inside the battery, the cooling layer and the protective layer simulate normal operation, and the temperature sensor can detect the temperature inside the battery in real time. Both can be connected to the PLC controller, and the control and detection of the temperature inside the battery are realized through the PLC controller.

[0034] Set an infrared thermometer on the test bench and use it to monitor the surface temperature of the chassis in the battery area of new energy vehicles in real time. Measure the temperature once every second, and use 5s as a test cycle. Divide 1 minute into 12 test cycles. Calculate the average temperature of each test cycle, and then calculate the average of the averages of all test cycles within 1 minute as the surface temperature of the chassis in the battery pack area of the new energy vehicle during this 1 minute (i.e., the entire initial test stage). The subsequent temperature measurement principle is the same.

[0035] By controlling the temperature rise inside the battery and monitoring the surface temperature of the chassis in the battery pack area of new energy vehicles, the ambient temperature during the test is 12.6°C. In this experiment. The final experimental results are shown in Table 1 and Table 2. Among them, Table 1 shows the data at intervals of 1 minute and 2 minutes, and Table 2 shows the data at intervals of 3 minutes, 4 minutes, and 5 minutes.

[0036] Table 1

[0037] Table 2

[0038] In Table 1, B 1 represents the temperature rise of the surface of the chassis in the battery pack area of new energy vehicles every 1 minute. For example, at the 6th minute, B 1 corresponds to the temperature difference between the 6th minute and the 5th minute, that is, 13.5 - 13.1 = 0.4°C, and so on for the rest. B 2 represents the temperature rise of the surface of the chassis in the battery pack area of new energy vehicles every 2 minutes. For example, at the 7th minute, B 2 corresponds to the temperature difference between the 7th minute and the 5th minute, that is, 14.4 - 13.1 = 1.3°C, and so on for the rest.

[0039] From Table 1 and Table 2, we can draw the following conclusions: (1) Through the algorithm disclosed in this application, the calculated temperature rise inside the battery is roughly the same as the actual temperature rise of the battery pack of new energy vehicles (the error is basically controlled within 2°C, and when t 1 is relatively small, the calculated value is closer to the actual value), that is, it is feasible to roughly estimate the temperature rise inside the battery through the temperature rise of the surface of the chassis in the battery pack area of new energy vehicles in this application.

[0040] (2) In the initial stage, from 0 to 5 minutes, the internal temperature of the battery rises by about 46°C. Although the internal temperature of the battery rises rapidly, the temperature of the chassis surface in the battery pack area of ​​the new energy vehicle does not change much, and the difference with the ambient temperature is within 0.5°C. This is because it has a multi-layer structure including a battery pack, a cooling layer, an insulating shock absorbing layer, and a protective layer, and the transfer of heat takes a certain amount of time. Therefore, the surface temperature of the chassis in the battery pack area of ​​the new energy vehicle does not change much. But later, the heat has basically been transferred to the surface of the chassis in the battery pack area of ​​the new energy vehicle, and the trend of the internal temperature rise of the battery is almost consistent. After that, the temperature rise of the internal battery is calculated using the temperature rise of the chassis surface in the battery pack area of ​​the new energy vehicle, and the actual internal temperature rise is within a reasonable error range, proving that the method of this application is feasible.

[0041] (3) In this example, the surface temperature rise B is 2.4°C at the 9th and 6th minutes, and the calculated △T N It is 12.8℃, which has exceeded 10℃. Therefore, in the 9th minute it can be determined that there is a possibility of thermal runaway inside the battery and an early warning needs to be issued. Example

[0042] First, heat the battery to 60°C and maintain it for 15 minutes. Then, take the moment of 15 minutes as the starting point of the test (i.e., 0 minutes in the table). Control the internal temperature of the battery. The specific experimental results are shown in Tables 3 and 4. Table 3 shows the data at intervals of 1 minute and 2 minutes, and Table 4 shows the data at intervals of 3 minutes.

[0043] Table 3

[0044] Table 4

[0045] In Table 3 and Table 4, B 1 It indicates the temperature rise of the chassis surface of the battery pack area of ​​the new energy vehicle every 1 minute. For example, at the 1st minute, B 1 The corresponding value is the temperature difference between the 1st minute and the 0th minute, that is, 28.7-28.6=0.1℃, and the rest are similar. 3 It means that the temperature rise of the chassis surface of the battery pack area of ​​the new energy vehicle increases every 3 minutes. For example, at the 3rd minute, B 2 The corresponding value is the temperature difference between the 3rd minute and the 0th minute, that is, 29.1-28.6=0.5℃, and so on.

[0046] From Table 3 and Table 4, we can draw the following conclusions: (1) From 1 to 4 minutes, when the internal temperature of the battery rises slowly (with an average temperature rise of 1 °C / min), the temperature of the chassis surface in the area of the new energy vehicle battery pack also rises slightly. From 4 to 8 minutes, the internal temperature rise of the battery accelerates, and the temperature rise of the chassis surface in the area of the new energy vehicle battery pack also accelerates synchronously. That is, we can infer the large temperature rise change inside the battery by monitoring the relatively small temperature rise change of the chassis surface in the area of the new energy vehicle battery pack.

[0047] (2) In this embodiment, the total temperature rise from the 5th to the 8th minute exceeds 10 °C. Therefore, at the 8th minute, it can be determined that there is a possibility of thermal runaway inside the battery, and a warning needs to be issued. Embodiment

[0048] The ambient temperature of the experiment is 15.7 °C. The obtained test results are shown in Table 5 and Table 6. Among them, Table 5 shows the data at intervals of 1 minute and 2 minutes, and Table 6 shows the data at intervals of 3 minutes, 4 minutes, and 5 minutes.

[0049] Table 5

[0050] Table 6

[0051] In Table 5 and Table 6, B1 represents the temperature rise of the chassis surface in the area of the new energy vehicle battery pack every 1 minute. For example, at the 6th minute, the value corresponding to B1 is the temperature difference between the 6th minute and the 5th minute, that is, 16.5 - 16.2 = 0.3 °C, and so on for the rest. B2 represents the temperature rise of the chassis surface in the area of the new energy vehicle battery pack every 5 minutes. For example, at the 10th minute, the value corresponding to B2 is the temperature difference between the 10th minute and the 5th minute, that is, 18.7 - 16.2 = 2.5 °C, and so on for the rest.

[0052] From Table 5 and Table 6, we can draw the following conclusions: (1) From 0 to 5 minutes, although the internal temperature of the battery rises rapidly, the temperature change of the chassis surface in the area of the new energy vehicle battery pack is not significant, which is similar to the conclusion of Embodiment 1 and will not be elaborated here.

[0053] (2) Starting from the 5th minute, as the internal temperature of the battery continues to rise slowly, the temperature of the chassis surface in the area of the new energy vehicle battery pack also gradually increases, and the two have the same trend. Moreover, inferring the temperature rise inside the battery through the temperature rise of the chassis surface in the area of the new energy vehicle battery pack has little difference from the actual temperature rise inside the battery, indicating that the algorithm of this application is feasible.

[0054] (3) In this embodiment, at the 10th minute, the B between the 10th minute and the 6th minute is 2.2 °C, and the calculated △TN is 11.9°C, exceeding 10°C, so a warning can be issued at the 10th minute.

[0055] The above description of the embodiments is to enable those of ordinary skill in the art to understand and apply this application. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, this application is not limited to the embodiments here, and the improvements and modifications made by those skilled in the art without departing from the scope and spirit of this application are within the scope of this application.

Claims

1. A method for monitoring abnormal temperature of a new energy vehicle battery pack, characterized in that: The method comprises the following steps: (1) Obtain the chassis surface temperature T of the battery pack area of ​​the new energy vehicle w And the ambient temperature T0, if T w -T0>0.5℃, then execute step (2), otherwise stop executing; (2) Obtain the change in chassis surface temperature of the battery pack area of ​​the new energy vehicle within a period of time t1 B = T w2 -T w1 ; Among them, T w1 is the initial chassis surface temperature of the new energy vehicle battery pack area during this period, T w2 is the surface temperature of the chassis of the battery pack area of ​​the new energy vehicle at the end of the period, and (T0+0.5)°C is used as the initial value; if B>0, execute step (3); if B<0, stop executing; (3) Calculate the internal temperature rise △T of the new energy vehicle battery pack after t1 N = K×B+△T, where K is the proportionality coefficient and △T is the temperature correction value; (4) Make a judgment when the internal temperature rises △T N If it exceeds the safe range, the temperature of the new energy vehicle battery pack is judged to be abnormal.

2. The method for monitoring abnormal temperature of a new energy vehicle battery pack according to claim 1, characterized in that: If 0≤B≤0.4, K=5.5, △T=-0.2; If 0.4<B<1, K=5, △T=0; If 1≤B<2, K=4.5, △T=0.5; If B≥2, K=4.5, △T=2.

3. The method for monitoring abnormal temperature of a new energy vehicle battery pack according to claim 1, characterized in that: The t1 is selected from a fixed value between 1 and 6 minutes.

4. The method for monitoring abnormal temperature of a new energy vehicle battery pack according to claim 3, characterized in that: The internal temperature rise ΔT N Exceeding the first safety range: During the t1 period, from the beginning to the end of the period, the internal temperature rise △T N >10℃.

5. The method for monitoring abnormal temperature of a new energy vehicle battery pack according to claim 1, characterized in that: Chassis surface temperature T of the battery pack area of ​​new energy vehicles w It is measured by an infrared thermometer, and the infrared thermometer measures once every 1s, and each t3 is a test cycle. t3 is a fixed value between 5 and 20s. The average temperature of each test cycle is T a , T w is the average temperature of all test cycles within one minute, that is, T w =(T a1 +T a2 +……+T an ) / n.

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