Battery pack thermal safety detection method and system

Abstract

The present invention provides a battery pack thermal safety detection method and system, which relates to the field of battery pack detection technology. The method includes: setting N temperature sensors on the top of the battery pack, and running the battery pack for a detection cycle according to the maximum charge and discharge power; obtaining the first temperature data and the second temperature data of the top of the battery pack; determining the abnormal score of the external temperature change of the battery pack; determining the external thermal safety status of the battery pack according to the abnormal score of the external temperature change, the first preset threshold and the second preset threshold; determining the uniform heating status of multiple cells of the battery pack according to the external thermal safety status of the battery pack; determining the internal thermal safety status of the battery pack according to the uniform heating status and the third preset threshold; determining the target cell of the battery pack according to the internal thermal safety status of the battery pack. According to the present invention, the temperature status of the cells inside the battery pack can be detected, so as to quickly and accurately find the target cell with abnormal heating.

Description

Technical Field

[0001] The present invention relates to the field of battery pack detection technology, and in particular to a battery pack thermal safety detection method and system. Background Art

[0002] In the related technology, CN106785197A provides a thermal management system for a new energy vehicle combined battery pack. The high temperature of the battery pack is detected by a high temperature detection module. When high temperature is detected, the control module controls the fan and the semiconductor refrigeration module to cool down together or individually according to actual conditions. If high temperature is not detected, the fan and the semiconductor refrigeration module will not work. A wireless transmission module is set to connect to a vehicle-mounted terminal to facilitate viewing of the specific cooling working status, a storage module is set to store data such as temperature and working status, and a WiFi module is set to connect to a user terminal to facilitate users to observe the cooling status through mobile devices. All-round cooling manages the heat of the new energy vehicle combined battery pack well.

[0003] CN113921942A relates to a new energy rapid cooler, a cooling method for a battery pack, and a car, including: a detection device for obtaining the real-time pressure value and real-time temperature value of the battery pack; a control system for judging the state of the battery pack and issuing instructions according to the state of the battery pack; a rapid cooling system for executing the instructions issued by the control system and spraying liquid inert gas to reduce the temperature inside the battery pack through the vaporization and heat absorption process of the liquid inert gas; and a battery pack explosion-proof valve for discharging the vaporized inert gas. This method can determine whether the battery pack is in a thermal runaway state; a rapid cooling system is provided, and when the battery pack is in a thermal runaway state, the rapid cooling system can quickly cool down, reduce the chain reaction when the battery cell is in thermal runaway, and effectively deal with the problem of excessive heat and fire in the battery pack after the thermal runaway of the battery pack.

[0004] Therefore, in the related art, only the temperature condition of the entire battery pack is detected, but the temperature condition of the battery cells inside the battery pack is not detected, so it is impossible to quickly and accurately find the abnormally hot target battery cells, resulting in the inability to quickly take targeted measures when thermal runaway occurs in the battery pack.

[0005] The information disclosed in the background technology section of this application is only intended to deepen the understanding of the general background technology of this application, and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art. Summary of the invention

[0006] The present invention provides a battery pack thermal safety detection method and system, which can solve the technical problem of being unable to quickly and accurately find a target battery cell with abnormal heating.

[0007] According to a first aspect of the present invention, a battery pack thermal safety detection method is provided, comprising: arranging N temperature sensors on the top of the battery pack, and operating the battery pack for a detection cycle according to the maximum charge and discharge power, wherein one detection cycle is divided into a first preset time period and a second preset time period of equal duration, the first preset time period is before the second preset time period, and N is a positive integer; obtaining first temperature data of the top of the battery pack at multiple moments in the first preset time period; obtaining second temperature data of the top of the battery pack at multiple moments in the second preset time period; determining an external temperature change abnormality score of the battery pack based on the first temperature data and the second temperature data; determining an external thermal safety status of the battery pack based on the external temperature change abnormality score, a first preset threshold value, and a second preset threshold value, wherein the first preset threshold value is greater than the second preset threshold value; determining a uniform heating status of multiple cells of the battery pack based on the external thermal safety status of the battery pack; determining an internal thermal safety status of the battery pack based on the uniform heating status and a third preset threshold value; determining a target cell of the battery pack based on the internal thermal safety status of the battery pack.

[0008] According to a second aspect of the present invention, a battery pack thermal safety detection system is provided, comprising: a maximum power operation module, used to respectively set N temperature sensors on the top of the battery pack, and operate the battery pack for a detection cycle according to the maximum charge and discharge power, wherein one detection cycle is divided into a first preset time period and a second preset time period of equal duration, the first preset time period is before the second preset time period, and N is a positive integer; a first temperature data module, used to obtain first temperature data of the top of the battery pack at multiple moments in the first preset time period; a second temperature data module, used to obtain second temperature data of the top of the battery pack at multiple moments in the second preset time period; an external temperature change abnormality scoring module, used to An external temperature change abnormality score of the battery pack is determined based on the first temperature data and the second temperature data; an external thermal safety status module is used to determine the external thermal safety status of the battery pack based on the external temperature change abnormality score, a first preset threshold and a second preset threshold, wherein the first preset threshold is greater than the second preset threshold; a heating uniformity status module is used to determine the heating uniformity status of multiple cells in the battery pack based on the external thermal safety status of the battery pack; an internal thermal safety status module is used to determine the internal thermal safety status of the battery pack based on the heating uniformity status and a third preset threshold; a target cell module is used to determine the target cell of the battery pack based on the internal thermal safety status of the battery pack.

[0009] Technical effect: According to the present invention, by setting multiple temperature sensors on the top of the battery pack and performing detection cycles according to the maximum charge and discharge power, the temperature changes of the battery pack can be fully monitored and the monitoring effect of the battery pack status can be improved. By comparing the top temperature data of the first preset time period and the second preset time period, the abnormal score of the external temperature change of the battery pack is evaluated, and the abnormal situation of the external temperature change of the battery pack can be discovered in time. The external thermal safety status of the battery pack helps to understand the external heat situation. The heat distribution of the internal cells of the battery pack can be evaluated by the uniform heating of multiple cells in the battery pack to reduce the risk of local overheating. The target cell with abnormal heating can be found quickly and accurately according to the internal thermal safety status of the battery pack. By comprehensively considering the external thermal safety status and internal thermal safety status of the battery pack, targeted treatment can be quickly made when thermal runaway occurs in the battery pack. When determining the abnormal score of the external temperature change of the battery pack, the temperature change of the top of the battery pack in different time periods can be compared to detect abnormal temperature changes. That is, the relationship between the first temperature change and the second temperature change can be used to determine whether the external temperature change of the battery pack is abnormal, so that the temperature change abnormality score can accurately describe the abnormal situation of the external temperature change of the battery pack. When determining the uniform heating condition of multiple cells in the battery pack, the uniform heating condition of multiple cells in the battery pack can be represented based on the difference between the temperatures of each cell in the battery pack at the end of the second preset time period. In this way, the temperature distribution of each cell in the battery pack is objectively and accurately described, and the uniformity of heating inside the battery pack is determined. It is helpful to timely discover the temperature unevenness that may exist inside the battery pack. When determining whether the cell to be tested is the target cell, the comprehensive score obtained by multiplying the current error score and the voltage error score can be used to consider the errors of the two important parameters of current and voltage, and more comprehensively evaluate whether the cell to be tested meets the standard of the target cell. In this way, the target cell can be found quickly and accurately, and the single target cell can be powered off or the entire battery pack can be replaced in time, so that the battery pack can operate safely.

[0010] It should be understood that the above general description and the following detailed description are exemplary and explanatory only and do not limit the present invention. Other features and aspects of the present invention will become more apparent from the following detailed description of exemplary embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use 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 those of ordinary skill in the art, other embodiments can be obtained based on these drawings without creative work.

[0012] Figure 1 A schematic diagram exemplarily shows a flow chart of a battery pack thermal safety detection method according to an embodiment of the present invention;

[0013] Figure 2 A block diagram of a battery pack thermal safety detection system according to an embodiment of the present invention is exemplarily shown. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] The technical solution of the present invention is described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0016] Figure 1 A flow chart of a method for thermal safety detection of a battery pack according to an embodiment of the present invention is exemplarily shown, the method comprising: step S101, N temperature sensors are respectively arranged on the top of the battery pack, and the battery pack is operated for a detection cycle according to the maximum charge and discharge power, wherein one detection cycle is divided into a first preset time period and a second preset time period of equal duration, the first preset time period is before the second preset time period, and N is a positive integer; step S102, at multiple moments in the first preset time period, first temperature data of the top of the battery pack is obtained; step S103, at multiple moments in the second preset time period, second temperature data of the top of the battery pack is obtained; step S104, at multiple moments in the second preset time period, second temperature data of the top of the battery pack is obtained; step S105, at multiple moments in the second preset time period, second temperature data of the top of the battery pack is obtained; step S106, at multiple moments in the second preset time period, Step S104, determining an external temperature change abnormality score of the battery pack according to the first temperature data and the second temperature data; step S105, determining an external thermal safety status of the battery pack according to the external temperature change abnormality score, a first preset threshold and a second preset threshold, wherein the first preset threshold is greater than the second preset threshold; step S106, determining a heating uniformity condition of multiple cells in the battery pack according to the external thermal safety status of the battery pack; step S107, determining an internal thermal safety status of the battery pack according to the heating uniformity condition and a third preset threshold; step S108, determining a target cell of the battery pack according to the internal thermal safety status of the battery pack.

[0017] According to the battery pack thermal safety detection method of an embodiment of the present invention, by setting multiple temperature sensors on the top of the battery pack and performing detection cycles according to the maximum charge and discharge power, the temperature changes of the battery pack can be fully monitored and the monitoring effect of the battery pack status can be improved. By comparing the top temperature data of the first preset time period and the second preset time period, the abnormal score of the external temperature change of the battery pack is evaluated, and the abnormal situation of the external temperature change of the battery pack can be discovered in time. The external thermal safety status of the battery pack helps to understand the external heat situation. The heat distribution of the internal cells of the battery pack can be evaluated by the uniform heating condition of multiple cells in the battery pack to reduce the risk of local overheating. According to the internal thermal safety status of the battery pack, the target cell with abnormal heating can be found quickly and accurately. By comprehensively considering the external thermal safety status and internal thermal safety status of the battery pack, targeted processing can be quickly made when thermal runaway occurs in the battery pack.

[0018] According to one embodiment of the present invention, in step S101, N temperature sensors are arranged on the top of the battery pack to monitor the temperature change of the battery pack during the charging and discharging process. The battery pack is operated according to the maximum power requirement of charging and discharging to test the safety performance of the battery pack under the most prone to heat. At the same time, a detection cycle is divided into a first preset time period and a second preset time period for effective monitoring and operation. Among them, the first preset time period and the second preset time period can be set to 20 minutes, 30 minutes, etc., and the present invention is not limited to this.

[0019] According to an embodiment of the present invention, in step S102, the temperature of the top of the battery pack is measured at multiple moments within a first preset time period to obtain first temperature data for subsequent analysis or monitoring. The interval between adjacent moments can be set to 2 minutes, 3 minutes, etc., and the present invention is not limited to this.

[0020] According to an embodiment of the present invention, in step S103, the temperature of the top of the battery pack is measured at multiple times within a second preset time period to obtain second temperature data for subsequent analysis or monitoring.

[0021] According to one embodiment of the present invention, in step S104, the first temperature data and the second temperature data are compared and analyzed, including considering the change, trend and possible abnormal fluctuation of the temperature values ​​in the two time periods. The abnormal score of the external temperature change of the battery pack helps to timely identify the abnormal external temperature problem of the battery pack.

[0022] According to one embodiment of the present invention, step S104 includes: obtaining N initial temperature data of N temperature sensors at the initial moment of a first preset time period and N first end temperature data at the end moment of the first preset time period based on the first temperature data; obtaining the average initial temperature of the top of the battery pack based on the N first end temperature data; obtaining the average first end temperature of the top of the battery pack based on the N first end temperature data; determining the first temperature change of the outside of the battery pack in the first preset time period based on the average initial temperature of the top and the average first end temperature of the top; obtaining N second end temperature data of N temperature sensors at the end moment of a second preset time period based on the second temperature data; obtaining the average second end temperature of the top of the battery pack based on the N second end temperature data; determining the second temperature change of the outside of the battery pack in the second preset time period based on the average first end temperature of the top and the average second end temperature of the top; determining the abnormal score of the external temperature change of the battery pack based on the first temperature change and the second temperature change.

[0023] According to one embodiment of the present invention, the first temperature change of the battery pack within the first preset time period is determined by using the data of the top average initial temperature and the top average first end temperature. The first temperature change represents the temperature change of the top of the battery pack within the first preset time period. The second temperature change represents the temperature change of the top of the battery pack within the second preset time period using the data of the top average first end temperature and the top average second end temperature. Based on the first temperature change and the second temperature change, the external temperature change of the battery pack is compared and analyzed to determine whether the battery pack has abnormal temperature fluctuations.

[0024] According to an embodiment of the present invention, determining the abnormality score of the external temperature change of the battery pack according to the first temperature change amount and the second temperature change amount includes: determining the abnormality score T of the external temperature change of the battery pack according to formula (1),

[0025]

[0026] Wherein, ΔT1 is a first temperature change of the exterior of the battery pack in a first preset time period, ΔT2 is a second temperature change of the exterior of the battery pack in a second preset time period, and if is a conditional function.

[0027] According to one embodiment of the present invention, in formula (1), Indicates that when the second temperature change is greater than or equal to the first temperature change, the conditional function value is Otherwise, the conditional function value is 0. When ΔT2<ΔT1, it means that the temperature change in the second preset time period is smaller than the temperature change in the first preset time period, the temperature rise rate decreases, and the temperature rise amplitude is within the controllable range, then the battery pack's external temperature change abnormality score is set to 0. When ΔT2≥ΔT1, it means that the temperature change rate is gradually increasing, and there is an abnormality in the temperature rise amplitude at the top of the battery pack. For example, the top of the battery pack may be due to excessive temperature caused by uniform heat distribution of the battery cells or abnormal heat caused by local overheating of a single battery cell. In this case, the battery pack's external temperature change abnormality score is set to 0. The higher the external temperature change abnormality score is, the more abnormal the temperature change outside the battery pack is.

[0028] In this way, the temperature change of the top of the battery pack in different time periods can be compared to detect abnormal temperature changes. That is, the relationship between the first temperature change amount and the second temperature change amount can be used to determine whether the external temperature change of the battery pack is abnormal, so that the temperature change abnormality score can accurately describe the abnormal temperature change of the external temperature of the battery pack.

[0029] According to one embodiment of the present invention, in step S105, the first preset threshold and the second preset threshold are used to determine the severity of the abnormal external temperature change. According to the comparison result of the external temperature change abnormality score with the first preset threshold and the second preset threshold, the external thermal safety status of the battery pack can be determined. According to the evaluation result of the external thermal safety status, corresponding safety measures and management strategies can be formulated to ensure that the battery pack operates stably within a safe temperature range and prevent the occurrence of potential risks and failures.

[0030] According to one embodiment of the present invention, step S105 includes: when the external temperature change abnormality score is greater than a first preset threshold, determining the external thermal safety status of the battery pack as unsafe; when the external temperature change abnormality score is less than or equal to the first preset threshold and greater than a second preset threshold, determining the external thermal safety status of the battery pack as a state to be detected; when the external temperature change abnormality score is less than or equal to the second preset threshold, determining the external thermal safety status of the battery pack as safe.

[0031] According to one embodiment of the present invention, based on the comparison of the abnormal score of the external temperature change with the first preset threshold, if the abnormal score of the external temperature change is greater than the first preset threshold, the external thermal safety status of the battery pack is determined to be unsafe, that is, the external temperature change is abnormal and serious, and there may be a safety risk. At this time, the entire battery pack needs to be replaced. If the abnormal score of the external temperature change is less than or equal to the first preset threshold, it is compared with the second preset threshold. If the abnormal score of the external temperature change is less than or equal to the first preset threshold and greater than the second preset threshold, the external thermal safety status of the battery pack is determined to be a state to be detected, and further detection is required. If the abnormal score of the external temperature change is less than or equal to the second preset threshold, the external thermal safety status of the battery pack is determined to be safe, that is, the external temperature change is normal, the safety status is good, and no special intervention is required.

[0032] According to an embodiment of the present invention, in step S106, a temperature sensor is used to detect the temperature of each battery cell in the battery pack. The temperature data can be used to evaluate the heating condition of the battery cell and whether there is a temperature unevenness phenomenon, so as to determine the uniform heating condition of multiple battery cells in the battery pack. If the temperature difference of each battery cell is small, it means that the heating of the battery cell is relatively uniform; if there is a significant temperature difference, it means that there is a condition of uneven heating.

[0033] According to one embodiment of the present invention, step S106 includes: if the external thermal safety status of the battery pack is in a state to be detected, obtaining the temperatures of multiple battery cells in the battery pack at the end of a second preset time period by an internal temperature sensor arranged on each battery cell in the battery pack; and determining the uniform heating condition of the multiple battery cells in the battery pack based on the temperatures of the multiple battery cells in the battery pack at the end of the second preset time period.

[0034] According to one embodiment of the present invention, if the external thermal safety status of the battery pack is in a to-be-detected state, it means that the temperature of multiple battery cells in the battery pack needs to be further detected, and the heating uniformity of the battery cells inside the battery pack is evaluated based on the temperature data of the multiple battery cells in the battery pack at the end of the second preset time period obtained by the internal temperature sensor, that is, the heating uniformity of the multiple battery cells in the battery pack.

[0035] According to an embodiment of the present invention, determining the uniform heating condition of the multiple cells of the battery pack according to the temperatures of the multiple cells of the battery pack at the end of the second preset time period includes: determining the uniform heating condition D of the multiple cells of the battery pack according to formula (2),

[0036]

[0037] Among them, t 2，i，fis the temperature of the i-th battery cell of the battery pack at the end of the second preset time period, M is the number of battery cells in the battery pack, i≤M, and i and M are both positive integers.

[0038] According to one embodiment of the present invention, in formula (2), The variance of each cell temperature indicates the uniformity of the temperature distribution of multiple cells in the battery pack, that is, the uniformity of the heating of multiple cells in the battery pack. If the variance value is small, it means that the temperature distribution of each cell is relatively uniform. Otherwise, it means that the temperature difference between the cells is large and the heating is uneven.

[0039] In this way, the temperature difference between the cells of the battery pack at the end of the second preset time period can be used to indicate the uniformity of the heating of the multiple cells in the battery pack. This objectively and accurately describes the temperature distribution of the cells in the battery pack and determines the uniformity of the heating inside the battery pack. This helps to promptly detect the temperature non-uniformity that may exist inside the battery pack.

[0040] According to an embodiment of the present invention, in step S107, the heating uniformity of the battery cells inside the battery pack is compared with the third preset threshold, and the internal thermal safety status of the battery pack is determined based on the comparison result. According to the evaluation result of the internal thermal safety status, corresponding maintenance measures and management strategies are formulated to prevent overheating or other safety problems.

[0041] According to one embodiment of the present invention, step S107 includes: if the heating uniformity condition is less than a third preset threshold, the internal thermal safety condition of the battery pack is determined to be safe; if the heating uniformity condition is greater than or equal to the third preset threshold, the internal thermal safety condition of the battery pack is determined to be unsafe.

[0042] According to one embodiment of the present invention, if the heating uniformity condition is less than the third preset threshold, it means that the temperature distribution inside the battery pack is relatively uniform. At this time, the internal thermal safety condition is determined to be safe, and the cooling fan is turned on for cooling so that the temperature inside the battery pack does not continue to rise. If the heating uniformity condition is greater than or equal to the third preset threshold, it means that the temperature distribution of the battery cells in the battery pack is not uniform enough, some areas may be overheated, and there are abnormally heated cells. In this case, the internal thermal safety condition will be determined to be unsafe, and the abnormally heated cells can be found at this time.

[0043] According to one embodiment of the present invention, in step S108, the target cell of the battery pack is found quickly and accurately according to the internal thermal safety status of the battery pack. The target cell of the battery pack is an abnormally heated cell. This helps to find the target cell in time and process the target cell.

[0044] According to one embodiment of the present invention, step S108 includes: if the internal thermal safety status of the battery pack is determined to be unsafe, determining the target battery cell of the battery pack according to the temperature of the battery cell of the battery pack at the end of the second preset time period, the fourth preset threshold and the fifth preset threshold, wherein the fourth preset threshold is greater than the fifth preset threshold; if the temperature of the i-th battery cell of the battery pack at the end of the second preset time period is greater than the fourth preset threshold, determining the i-th battery cell as the target battery cell; if the temperature of the i-th battery cell of the battery pack at the end of the second preset time period is less than or equal to the fourth preset threshold and greater than the fifth preset threshold, determining The i-th battery cell is determined to be the battery cell to be tested; if the temperature of the i-th battery cell of the battery pack at the end of the second preset time period is less than or equal to the fifth preset threshold value, the i-th battery cell is determined to be a non-target battery cell; the current of the battery cell to be tested and the voltage of the battery cell to be tested are obtained; the temperature of the battery cell, the current of the battery cell and the voltage of the battery cell are processed by a trained battery cell state prediction model to obtain the standard current and standard voltage of the battery cell at different temperatures; according to the standard current, the current of the battery cell to be tested, the current error, the standard voltage, the voltage of the battery cell to be tested and the voltage error, it is determined whether the battery cell to be tested is the target battery cell.

[0045] According to one embodiment of the present invention, if the internal heat safety condition is determined to be unsafe, then according to the end time of the second preset time period, the temperature of each battery cell in the battery pack is recorded, and the temperature of the ith battery cell is compared with the fourth preset threshold value. If the temperature of the ith battery cell is greater than the fourth preset threshold value, the ith battery cell is determined as the target battery cell, and the target battery cell is powered off. When the temperature of the ith battery cell is less than or equal to the fourth preset threshold value, the temperature of the ith battery cell is compared with the fifth preset threshold value. If the temperature of the ith battery cell at this time is greater than the fifth preset threshold value, the ith battery cell is determined as the battery cell to be tested, and the detection is continued to determine whether the battery cell to be tested is the target battery cell. If the temperature of the ith battery cell is less than or equal to the fifth preset threshold value, the ith battery cell is determined as a non-target battery cell and is used normally. According to the determination of the battery cell to be tested, the current data of the battery cell to be tested and the voltage data of the battery cell to be tested are obtained, and the temperature of the battery cell to be tested at this time is processed by the trained battery cell state prediction model to obtain the standard current and standard voltage at the temperature of the battery cell to be tested at this time. Among them, the cell state prediction model is a neural network model, which can output the current data and voltage data under the cell temperature and when the cell state is normal, that is, the standard current and standard voltage, based on the cell temperature. According to the standard current, the current of the cell to be tested, the current error, the standard voltage, the voltage of the cell to be tested, and the voltage error, it is judged whether the cell to be tested is the target cell.

[0046] According to an embodiment of the present invention, determining whether the cell to be tested is a target cell according to the standard current, the current of the cell to be tested, the current error, the standard voltage, the voltage of the cell to be tested, and the voltage error comprises: determining whether the cell to be tested is a target cell according to formulas (3), (4), and (5);

[0047] f=if(|I i，f -I i，T |≤ΔI,1,0) (3)

[0048] g=if(|V i，f -V i，T |≤ΔV,1,0) (4)

[0049] C=f×g (5)

[0050] Determine whether the cell to be tested is the target cell, where f is the current error score, I i，f is the current of the cell to be tested, I i，T is the standard current, ΔI is the preset current error, g is the voltage error score, V i，f is the voltage of the cell to be tested, V i，T is the standard voltage, ΔV is the preset voltage error, C is the comprehensive score, and if is the conditional function; when c=1, the cell to be tested is a non-target cell; when C=0, the cell to be tested is a target cell.

[0051] According to one embodiment of the present invention, in formula (3), if (|I i，f -I i，T |≤ΔI, 1, 0) is the current error score, indicating that when the difference between the current of the cell to be tested and the standard current is less than or equal to the preset current error, the conditional function value is 1, otherwise, the conditional function value is 0. That is, when the difference between the current of the cell to be tested and the standard current is within the preset current error range, the current of the cell to be tested is normal, indicating that the temperature of the cell to be tested may be affected by the temperature of the surrounding target cells, and therefore, the cell to be tested may be a non-target cell. When the difference between the current of the cell to be tested and the standard current is not within the preset current error range, the current of the cell to be tested is abnormal, indicating that the current change is caused by the abnormal temperature of the cell to be tested, and therefore, the cell to be tested is a target cell.

[0052] According to one embodiment of the present invention, in formula (4), if (|V i，f -V i，T|≤ΔV, 1, 0) is the voltage error score, indicating that when the difference between the voltage of the cell to be tested and the standard voltage is less than or equal to the preset voltage error, the conditional function value is 1, otherwise, the conditional function value is 0. That is, when the difference between the voltage of the cell to be tested and the standard voltage is within the preset voltage error range, the voltage of the cell to be tested is normal, indicating that the temperature of the cell to be tested may be affected by the temperature of the surrounding target cells, and therefore, the cell to be tested may be a non-target cell. When the difference between the voltage of the cell to be tested and the standard voltage is not within the preset voltage error range, the voltage of the cell to be tested is abnormal, indicating that the voltage change is caused by the abnormal temperature of the cell to be tested, and therefore, the cell to be tested is a target cell.

[0053] According to one embodiment of the present invention, in formula (5), by multiplying the current error score and the voltage error score, a comprehensive score can be obtained, which takes into account the errors in both current and voltage. If the errors in both current and voltage of the cell to be tested are within an acceptable range, that is, both f and g are 1, then the result of f×g is 1, indicating that the cell to be tested does not meet the standard of the target cell. If the errors in one or both of the aspects exceed the acceptable range, that is, f or g is 0, then the result of f×g is 0, indicating that the cell to be tested meets the standard of the target cell.

[0054] In this way, based on the comprehensive score obtained by multiplying the current error score and the voltage error score, the error of the two important parameters of current and voltage can be considered to more comprehensively evaluate whether the battery cell to be tested meets the standards of the target battery cell. In this way, the target battery cell can be found quickly and accurately, and the power of a single target battery cell can be cut off or the entire battery pack can be replaced in time to enable the battery pack to operate safely.

[0055] According to one embodiment of the present invention, when the ratio of the number of target battery cells to all battery cells in the battery pack is lower than a preset ratio threshold (for example, 5% or 10%), the determined single target battery cell is powered off; when the ratio of the number of target battery cells to all battery cells in the battery pack is higher than the preset ratio threshold, the entire battery pack is powered off and replaced.

[0056] According to the battery pack thermal safety detection method of the embodiment of the present invention, by setting multiple temperature sensors on the top of the battery pack and performing detection cycles according to the maximum charge and discharge power, the temperature change of the battery pack can be fully monitored and the monitoring effect of the battery pack status can be improved. By comparing the top temperature data of the first preset time period and the second preset time period, the abnormal score of the external temperature change of the battery pack is evaluated, and the abnormal situation of the external temperature change of the battery pack can be discovered in time. The external thermal safety status of the battery pack is helpful to understand the external heat situation. The heat distribution of the internal battery cells of the battery pack can be evaluated by the uniform heating of multiple battery cells in the battery pack, reducing the risk of local overheating. According to the internal thermal safety status of the battery pack, the target battery cell with abnormal heating can be found quickly and accurately. By comprehensively considering the external thermal safety status and internal thermal safety status of the battery pack, targeted processing can be quickly made when the battery pack has thermal runaway. When determining the abnormal score of the external temperature change of the battery pack, the temperature change of the top of the battery pack in different time periods can be compared to detect the abnormal temperature change. That is, the relationship between the first temperature change and the second temperature change can be used to determine whether the external temperature change of the battery pack is abnormal, so that the temperature change abnormality score can accurately describe the abnormal situation of the external temperature change of the battery pack. When determining the uniform heating condition of multiple cells in the battery pack, the uniform heating condition of multiple cells in the battery pack can be represented based on the difference between the temperatures of each cell in the battery pack at the end of the second preset time period. In this way, the temperature distribution of each cell in the battery pack is objectively and accurately described, and the uniformity of heating inside the battery pack is determined. It is helpful to timely discover the temperature unevenness that may exist inside the battery pack. When determining whether the cell to be tested is the target cell, the comprehensive score obtained by multiplying the current error score and the voltage error score can be used to consider the errors of the two important parameters of current and voltage, and more comprehensively evaluate whether the cell to be tested meets the standard of the target cell. In this way, the target cell can be found quickly and accurately, and the single target cell can be powered off or the entire battery pack can be replaced in time, so that the battery pack can operate safely.

[0057] Figure 2A block diagram of a battery pack thermal safety detection system according to an embodiment of the present invention is exemplarily shown, the system comprising: a maximum power operation module, used to respectively set N temperature sensors on the top of the battery pack, and operate the battery pack for a detection cycle according to the maximum charge and discharge power, wherein one detection cycle is divided into a first preset time period and a second preset time period of equal duration, the first preset time period is before the second preset time period, and N is a positive integer; a first temperature data module, used to obtain first temperature data of the top of the battery pack at multiple moments in the first preset time period; a second temperature data module, used to obtain second temperature data of the top of the battery pack at multiple moments in the second preset time period; an external temperature change abnormality scoring module A block is used to determine the external temperature change abnormality score of the battery pack according to the first temperature data and the second temperature data; an external thermal safety status module is used to determine the external thermal safety status of the battery pack according to the external temperature change abnormality score, a first preset threshold value and a second preset threshold value, wherein the first preset threshold value is greater than the second preset threshold value; a heating uniformity status module is used to determine the heating uniformity status of multiple cells in the battery pack according to the external thermal safety status of the battery pack; an internal thermal safety status module is used to determine the internal thermal safety status of the battery pack according to the heating uniformity status and a third preset threshold value; a target cell module is used to determine the target cell of the battery pack according to the internal thermal safety status of the battery pack.

[0058] According to one embodiment of the present invention, a battery pack thermal safety detection device is provided, comprising: a processor; a memory for storing processor executable instructions; wherein the processor is configured to call the instructions stored in the memory to execute the battery pack thermal safety detection method.

[0059] According to one embodiment of the present invention, there is provided a computer-readable storage medium having computer program instructions stored thereon, wherein the computer program instructions implement the battery pack thermal safety detection method when executed by a processor.

[0060] The present invention may be a method, an apparatus, a system and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for executing various aspects of the present invention.

[0061] It should be understood by those skilled in the art that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functional and structural principles of the present invention have been demonstrated and explained in the embodiments, and the embodiments of the present invention may be deformed or modified in any way without departing from the principles.

Claims

1. A battery pack thermal safety detection method, characterized in that: include: N temperature sensors are respectively arranged on the top of the battery pack, and the battery pack is operated for a detection cycle according to the maximum charge and discharge power, wherein one detection cycle is divided into a first preset time period and a second preset time period of equal duration, the first preset time period is before the second preset time period, and N is a positive integer; at multiple moments in the first preset time period, first temperature data of the top of the battery pack is obtained; at multiple moments in the second preset time period, second temperature data of the top of the battery pack is obtained; based on the first temperature data and the second temperature data, an abnormal score of an external temperature change of the battery pack is determined; based on the abnormal score of the external temperature change, a first preset threshold and a second preset threshold, an external thermal safety status of the battery pack is determined, wherein the first preset threshold is greater than the second preset threshold; based on the external thermal safety status of the battery pack, a uniform heating status of multiple cells of the battery pack is determined; based on the uniform heating status and a third preset threshold, an internal thermal safety status of the battery pack is determined; based on the internal thermal safety status of the battery pack, a target cell of the battery pack is determined; based on the abnormal score of the external temperature change, the first preset threshold and the second preset threshold, Determine the external thermal safety status of the battery pack, wherein the first preset threshold is greater than the second preset threshold, including: when the external temperature change abnormality score is greater than the first preset threshold, determine the external thermal safety status of the battery pack as unsafe; when the external temperature change abnormality score is less than or equal to the first preset threshold and greater than the second preset threshold, determine the external thermal safety status of the battery pack as a state to be detected; when the external temperature change abnormality score is less than or equal to the second preset threshold, determine the external thermal safety status of the battery pack as safe; determine the uniform heating status of multiple cells in the battery pack according to the external thermal safety status of the battery pack, including: if the external thermal safety status of the battery pack is a state to be detected, obtain the temperature of multiple cells in the battery pack at the end of the second preset time period through an internal temperature sensor set on each cell in the battery pack; determine the uniform heating status of multiple cells in the battery pack according to the temperature of multiple cells in the battery pack at the end of the second preset time period; determine the uniform heating status of multiple cells in the battery pack according to the temperature of multiple cells in the battery pack at the end of the second preset time period, including: according to the formula Determine the uniform heating condition D of multiple cells in the battery pack, where t 2，i，f is the temperature of the ith battery cell of the battery pack at the end of the second preset time period, M is the number of battery cells in the battery pack, i≤M, and i and M are both positive integers; according to the internal thermal safety status of the battery pack, the target battery cell of the battery pack is determined, including: if the internal thermal safety status of the battery pack is determined to be unsafe, then according to the temperature of the battery cell of the battery pack at the end of the second preset time period, the fourth preset threshold and the fifth preset threshold, the target battery cell of the battery pack is determined, wherein the fourth preset threshold is greater than the fifth preset threshold; if at the end of the second preset time period, the temperature of the ith battery cell of the battery pack is greater than the fourth preset threshold, then the ith battery cell is determined to be the target battery cell; if at the end of the second preset time period, the temperature of the ith battery cell of the battery pack is less than or equal to the fourth preset threshold and greater than the fifth preset threshold, then the ith battery cell is determined is a cell to be tested; if the temperature of the ith cell of the battery pack at the end of the second preset time period is less than or equal to the fifth preset threshold, the ith cell is determined to be a non-target cell; the current of the cell to be tested and the voltage of the cell to be tested are obtained; the temperature of the cell, the current of the cell and the voltage of the cell are processed by a trained cell state prediction model to obtain the standard current and standard voltage of the cell at different temperatures; according to the standard current, the current of the cell to be tested, the current error, the standard voltage, the voltage of the cell to be tested and the voltage error, it is determined whether the cell to be tested is a target cell; according to the standard current, the current of the cell to be tested, the current error, the standard voltage, the voltage of the cell to be tested and the voltage error, it is determined whether the cell to be tested is a target cell, including: according to the formula f=if(|I i，f -I i，T |≤ΔI,1,0), g=if(|V i，f -V i，T |≤ΔV,1,0), C=f×g to determine whether the cell to be tested is the target cell, where f is the current error score, I i，f is the current of the cell to be tested, I i，T is the standard current, ΔI is the preset current error, g is the voltage error score, V i，f is the voltage of the cell to be tested, V i，T is the standard voltage, ΔV is the preset voltage error, C is the comprehensive score, and if is the conditional function; when C=1, the cell to be tested is a non-target cell; when C=0, the cell to be tested is a target cell.

2. The battery pack thermal safety detection method according to claim 1, characterized in that: Determine the abnormal score of the external temperature change of the battery pack according to the first temperature data and the second temperature data, including: according to the first temperature data, obtain N initial temperature data of N temperature sensors at the initial moment of the first preset time period and N first end temperature data at the end moment of the first preset time period; according to the N initial temperature data, obtain the average initial temperature of the top of the battery pack; according to the N first end temperature data, obtain the average first end temperature of the top of the battery pack; according to the average initial temperature of the top and the average first end temperature of the top, determine the first temperature change of the outside of the battery pack in the first preset time period; according to the second temperature data, obtain N second end temperature data of N temperature sensors at the end moment of the second preset time period; according to the N second end temperature data, obtain the average second end temperature of the top of the battery pack; according to the average first end temperature of the top and the average second end temperature of the top, determine the second temperature change of the outside of the battery pack in the second preset time period; according to the first temperature change and the second temperature change, determine the abnormal score of the external temperature change of the battery pack.

3. The battery pack thermal safety detection method according to claim 2, characterized in that: Determining an abnormal score of an external temperature change of the battery pack according to the first temperature change and the second temperature change includes: according to the formula Determine the abnormal temperature change score T of the battery pack, where ΔT1 is the first temperature change of the battery pack's exterior in a first preset time period, ΔT2 is the second temperature change of the battery pack's exterior in a second preset time period, and if is a conditional function.

4. The battery pack thermal safety detection method according to claim 1, characterized in that: The internal thermal safety condition of the battery pack is determined based on the heating uniformity condition and the third preset threshold, including: if the heating uniformity condition is less than the third preset threshold, the internal thermal safety condition of the battery pack is determined to be safe; if the heating uniformity condition is greater than or equal to the third preset threshold, the internal thermal safety condition of the battery pack is determined to be unsafe.

5. A battery pack thermal safety detection system for executing the method according to any one of claims 1 to 4, characterized in that: include: The maximum power operation module is used to respectively set N temperature sensors on the top of the battery pack, and operate the battery pack for a detection cycle according to the maximum charge and discharge power, wherein one detection cycle is divided into a first preset time period and a second preset time period of equal duration, the first preset time period is before the second preset time period, and N is a positive integer; the first temperature data module is used to obtain the first temperature data of the top of the battery pack at multiple moments in the first preset time period; the second temperature data module is used to obtain the second temperature data of the top of the battery pack at multiple moments in the second preset time period; the external temperature change abnormality scoring module is used to score the external temperature change abnormality according to the first temperature data and the second temperature data. temperature data, determining an external temperature change abnormality score of the battery pack; an external thermal safety status module, used to determine the external thermal safety status of the battery pack according to the external temperature change abnormality score, a first preset threshold and a second preset threshold, wherein the first preset threshold is greater than the second preset threshold; a heating uniformity status module, used to determine the heating uniformity status of multiple cells in the battery pack according to the external thermal safety status of the battery pack; an internal thermal safety status module, used to determine the internal thermal safety status of the battery pack according to the heating uniformity status and a third preset threshold; a target cell module, used to determine the target cell of the battery pack according to the internal thermal safety status of the battery pack.

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