Method and motor vehicle for identifying thermal runaway

Abstract

The invention relates to a method for identifying thermal runaway in a battery pack of a motor vehicle, wherein a check process is performed after the operation or charging process of the battery pack has ended, wherein a time period is specified and after its expiration, a comparison of a temperature value of the battery pack with a target temperature value is performed, the target temperature value is determined by means of a temperature model, and a selection is made by means of the result of the comparison with the aid of an evaluation criterion, so that in a subsequent process, either the check process is performed again as the next check process, in the case of the next check process, a next time period is specified and after the expiration of the next time period, a next comparison of the next temperature value of the battery pack with the next target temperature value determined by means of the temperature model is performed, and a next selection is made by means of the result of the next comparison with the aid of an evaluation criterion, wherein the subsequent process is performed again as the next subsequent process according to the next selection; or a signal is output; or no other measures are taken. The invention also relates to a corresponding motor vehicle.

Description

Technical Field

[0001] The invention relates to a method for detecting a thermal runaway in a battery of a motor vehicle and to a motor vehicle designed for detecting a thermal runaway. Background Art

[0002] In motor vehicles, in particular such motor vehicles with electric or hybrid electric drives, there is the risk of thermal runaway, i.e. uncontrolled and undesirable thermal reactions in the form of heat generation, occurring in batteries, in particular traction batteries. Such thermal runaway can occur in particular in the case of lithium-ion batteries, which are often used as traction batteries in motor vehicles with electric or hybrid electric drives. The consequences can be, in particular, fires and / or explosions. It is therefore important that the motor vehicle user is prompted to leave the motor vehicle during use of the motor vehicle in the event of thermal runaway by appropriate warnings.

[0003] Safety requirements for battery packs in motor vehicles with electric or hybrid electric drive are laid down in various standards, guidelines and regulations. In this context, mention should be made, for example, of the national standard of the People's Republic of China "Electrical Vehicles Traction Battery Safety Requirements" (roughly in German: "Sicherheitsanforderungen von Antriebsbatterien elektrischerFahrzeuge"). This standard was issued by the "General Administration of Quality Supervision, Inspection and Quarantine" ("AQSIQ") (roughly in German: "Hauptamt für und ”) and the “China Standardization Administration” (roughly in German: Chinese Standardization Administration). In this national standard, in particular, safety requirements and specifications for safety testing of power battery packs are defined. In Europe, the UNECER 100 regulation will also be important in the future.

[0004] CN 110068768A discloses a method for detecting thermal runaway of a battery pack, wherein the method comprises:

[0005] - obtaining detected voltage values ​​at a plurality of voltage detection points in the battery pack and a plurality of detected temperature values ​​at a corresponding plurality of temperature detection points in the battery pack;

[0006] -calculating the temperature rise rate of the battery pack based on the detected temperature value;

[0007] - Based on the plurality of detected voltage values, the plurality of detected temperature values ​​and the temperature rise rate, determining whether thermal runaway occurs in the battery pack.

[0008] US2019 / 0036178 discloses a method for monitoring the temperature of a battery pack and providing an alarm message in the event of abnormal temperature, the method comprising:

[0009] - wirelessly receiving temperature measurement data from a single cell or a plurality of cells connected electrically in series or in parallel, wherein the temperature measurement data are the temperature within each cell of the plurality of cells;

[0010] - calculating a temperature value equal to an average of temperature measurement data wirelessly received from all cells of the plurality of cells in the battery pack;

[0011] - Calculate the high temperature difference as the absolute value of the difference between the highest cell temperature in the battery pack and this temperature value;

[0012] - calculating the low temperature difference as the absolute value of the difference between the lowest cell temperature in the battery pack and this temperature value; and - triggering an alarm if the high temperature difference is greater than a predetermined high temperature threshold or if the low temperature difference is greater than a predetermined low temperature threshold.

[0013] CN 107611513 A discloses a method for detecting thermal runaway of a lithium-ion battery pack in an electric vehicle, wherein a lithium-ion battery pack management system or BMS system for an electric vehicle is disclosed, which monitors the voltage and temperature of each battery of the battery pack. Summary of the invention

[0014] The technical problem underlying the invention is to more reliably detect a thermal runaway or an imminent thermal runaway of a battery pack in a motor vehicle. Another technical problem is to reduce the energy consumption resulting from monitoring the battery pack for the purpose of detecting a thermal runaway or an imminent thermal runaway. Another technical problem is to realize the detection of a thermal runaway or an imminent thermal runaway with low hardware technology expenditure and in an inexpensive and simple manner.

[0015] According to the basic idea of ​​the invention, the temperature value of the battery pack is checked so that it is compared with a target temperature value determined by a temperature model. This comparison is carried out after the expiration of a time period, wherein the time period begins after the end of the operation or charging process of the battery pack. The time period can especially begin immediately after the end of the operation or charging process of the battery pack. Alternatively, the time period can begin at a predefinable time interval after the end of the operation or charging process of the battery pack.

[0016] In particular, the operation may be a driving operation of a motor vehicle in which the battery pack is used. The charging process may in particular be a fast charging process. In the case of such a process, the battery pack may be subjected to high thermal loads. As a result, the probability of thermal runaway may increase. The battery pack may in particular be a traction battery pack of a motor vehicle.

[0017] The motor vehicle can be parked, in particular parked, and / or switched off, in particular after the operation has ended. In particular, the so-called ignition of the electric vehicle can be switched off. In particular, the low-voltage circuit (e.g. 12V or 48V circuit) of the motor vehicle can be switched off, or only a small current can flow in the low-voltage circuit. In particular, the high-voltage circuit (in particular the traction circuit and / or the 400V or 800V circuit) of the motor vehicle can also be switched off, or only a small current can flow in the high-voltage circuit.

[0018] The temperature value can be determined at least once, but can also be determined multiple times, in particular multiple times with time intervals. Between the end of the operation or the charging process and the first determination of the temperature value and between the first determination and the possible next determination, there is a time period, a time period at the beginning and perhaps a subsequent time period. The next time period can be shorter than the time period at the beginning. The subsequent time periods can also be shorter than the time period at the beginning or become shorter and shorter. Shorter time periods provide the following possibilities: particularly quickly identify thermal runaway or can quickly react to a developing or impending thermal runaway.

[0019] The next time period can also be longer than the time period at the beginning. The subsequent time periods can also be longer than the time period at the beginning or become longer and longer. Longer time periods provide good possibilities for identifying thermal runaway and monitoring the battery pack under low energy consumption.

[0020] Depending on the respective results of the comparison of the temperature value or the next temperature value with the target temperature value or the next target temperature value, a selection for the subsequent measures is made respectively by means of a predefined evaluation criterion. Then, it is concluded whether to execute the inspection process again, that is, to execute the next inspection process (including re-defining the next time period in a corresponding order, re-comparing, and re-selecting) or output a signal, or not to take other measures. The signal can especially be an alarm signal.

[0021] If no further measures are taken, this means in particular that no extensive checks are carried out. This may be the case if the result of the comparison leads to the assessment that no thermal runaway is considered to exist. If a thermal runaway is considered to exist based on the result of the comparison, the signal may be output in particular, in particular when a danger is imminent. Further checks are carried out if in particular a thermal runaway appears to be possible, may occur soon, or is imminent. This is also possible when a thermal runaway is already present, but does not pose an immediate danger, such as a fire or explosion hazard.

[0022] In particular, a method for identifying thermal runaway in a battery pack of a motor vehicle, in particular a motor vehicle with an electric drive or a hybrid electric drive, is proposed, wherein a check process is performed after the end of an operation or charging process of the battery pack, in the case of which a time period is specified and after expiration of the time period a comparison of a temperature value of the battery pack with a target temperature value is performed, wherein the target temperature value is determined with the aid of a temperature model that describes a target cooling of the battery pack, and with the aid of the result of the comparison a selection is made with the aid of a predefined evaluation criterion, so that in a subsequent process, either - the check process is performed again as the next check process, in the case of the next check process a next time period is specified and after expiration of the next time period a next comparison of a next temperature value of the battery pack with a next target temperature value determined with the aid of the temperature model is performed, and with the aid of the result of the next comparison a next selection is made with the aid of the evaluation criterion, wherein the subsequent process is performed again as the next subsequent process according to the next selection; or

[0023] - output signal; or

[0024] - No other action is taken.

[0025] The battery can be an electrochemical energy storage device in particular. The battery can be a lithium-ion battery in particular. The battery can be used in particular as a traction battery for a motor vehicle. The battery can also be used as an auxiliary traction battery, for example in a motor vehicle with a hybrid electric drive.

[0026] The check process starts at a point in time after the operation or the charging process has ended. The check process can be carried out immediately after the operation or the charging process. In particular, the check process can also be triggered when the motor vehicle is switched off, parked or locked or at a time interval after the process. The interval can be short, for example a few minutes (e.g. 1 to 10 minutes).

[0027] The method can be carried out in particular by means of a computing and control device of the motor vehicle. The method can be carried out in particular partially or completely automatically. The computing and control device can have in particular a computing unit, a memory, a working memory, at least one input device and at least one output device. The computing and control device can be designed to receive and send data, in particular wirelessly, for example via a mobile radio connection or via a wireless network. At least a part of the method or at least one step can be outsourced to a computer located outside the motor vehicle and connected to the computing and control device.

[0028] The computing and control device can be designed in particular to: specify a time period and / or, if a corresponding selection is made, to specify the next time period and possibly a plurality of subsequent time periods; and / or to implement a temperature model. The computing and control device can also be designed to: make a selection. The computing and control device can be designed to carry out a check process. Alternatively or additionally, the computing and control device can be designed to carry out a subsequent process, i.e. either to carry out the check process and the subsequent process again or to output a signal by means of an output device or to take no further measures.

[0029] The temperature value of the battery pack can be recorded by a temperature sensor. In a simple embodiment, only a single temperature value is used to compare with the target temperature value determined by the temperature model. In a more complex embodiment, multiple temperature values ​​can be used. Then, multiple temperature values ​​can be compared with multiple corresponding target temperature values. For example, the temperature value can be recorded and used for comparison at multiple different or all battery cells or battery blocks or modules or battery stacks or clusters present in the battery pack by means of temperature sensors. In particular, the average value of the temperature of multiple or all battery cells or battery blocks or modules or battery stacks or clusters can be used as the temperature value. It can be compared with the corresponding target average value. This average value can be determined in particular by means of the calculation and control device. The average value can be determined based on the temperature values ​​recorded by means of multiple sensors.

[0030] Alternatively or additionally, differences in temperature values ​​within the battery pack can be taken into account. It is possible to take into account the absolute value of the difference. This difference can be determined in particular by means of the calculation and control device. The difference can be determined based on temperature values ​​recorded by means of a plurality of (in particular two) temperature sensors. This difference can then be compared with a corresponding target difference. The target difference can be determined by means of a temperature model.

[0031] The difference can be in particular the maximum difference in temperature within the battery, in particular the maximum difference in temperature values ​​determined by a temperature sensor for different battery cells or battery blocks or modules or battery stacks or clusters. This maximum difference can then be compared with a maximum target difference. Temperature values ​​or differences between temperature values ​​can be recorded or determined at different possible points in time and used for comparison with corresponding target temperature values ​​determined with the aid of a temperature model. These temperature values ​​or differences between temperature values ​​can be recorded in particular at the start of the inspection process or at a point in time before the inspection process and / or after the expiration of the time period and / or after the expiration of the next time period, respectively.

[0032] The properties of the motor vehicle and / or the battery and / or the surroundings may be input variables or parameters or variables used in the temperature model or may be taken into account in the temperature model. In particular, these may be values ​​that relate to:

[0033] - Battery pack size;

[0034] -Battery pack weight;

[0035] - Geometric parameters of the battery pack;

[0036] - parameters relating to the state of charge of the battery pack; and / or

[0037] - Other physical characteristics of the battery pack (e.g. measurements from a pressure sensor or a voltage sensor).

[0038] For example, it may also involve:

[0039] - the time that has passed since the end of the operation or charging process;

[0040] - time period or next time period;

[0041] -The heat transfer coefficient or thermal conductivity of the battery pack;

[0042] - the heat transfer coefficient between the battery and the surrounding medium of the battery (possibly air);

[0043] - parameters regarding the age of the battery pack;

[0044] - parameters concerning the balancing behavior of the battery pack; or

[0045] -Ambient temperature value.

[0046] The temperature model may, for example, include a thermal simulation. Such a thermal model may, for example, be established by means of analytical or numerical methods or empirical methods. The temperature model may, for example, take into account Fourier's fundamental law of heat conduction or be based on it. The temperature model may include a simulation of the temperature development according to an exponential method. The temperature model may also include an FEM model, in particular an FEM model for simulating the temperature development, or be established on the basis of or based on this FEM model.

[0047] The determination of the result may include a subtraction, ie a difference, between a temperature value or a temperature difference and a corresponding target temperature value or a corresponding target temperature difference. That is, the result may be the result of such a subtraction. Alternatively or additionally, the result may be or include a qualitative statement.

[0048] The selection can be made with the aid of the evaluation criteria by means of the result of the comparison of a temperature value or a plurality of temperature values ​​and, if necessary, one or more of the temperature differences mentioned with the respectively corresponding target value. In a simple embodiment, only one temperature value is required to be compared with a target temperature value, wherein the temperature value is recorded at a point in time after the expiration of the time period.

[0049] The evaluation criterion can be expressed in particular in a mathematical manner. The evaluation criterion may include at least one threshold value. If the result, for example, the temperature difference between the temperature and the target temperature is greater than the threshold value, the selection may be determined so that the inspection process and the subsequent process are performed again or a signal is output. The evaluation criterion may have a plurality of threshold values. The threshold value may in particular define an interval. Depending on which interval the result is within, the inspection process and the subsequent process are performed again, a signal is output or no other measures are taken.

[0050] In the context of this evaluation criterion, various other sensor values ​​or other variables can be used or taken into account as input variables or parameters that can be additionally used for making this selection: For example, the value of a pressure sensor, in particular a pressure sensor on / in the battery, the value of a gas sensor that can, for example, detect outgassing of a battery cell, the value of an optical sensor that can, for example, detect a change in shape or opening of a battery cell or battery, the value of a voltage sensor at the battery, and / or a value that describes the balancing behavior of the battery. For example, voltage differences between different battery cells and / or a voltage value of at least one battery cell and / or an energy discharge value of a battery cell can be used.

[0051] This selection can be made in the form of an electronically processable selection value, for example. The selection value can be designed arbitrarily. In a simple form, the selection value is just one value from a selection of three values, which correspond to the different variants possible within the subsequent process.

[0052] Typically, the inspection process and the subsequent process can be performed again, especially when future or imminent thermal runaway is not excluded. If thermal runaway already exists, but fire and / or explosion of the battery pack is not expected to occur or has not yet occurred, the inspection process and the subsequent process can also be performed again. Other irrationalities in the battery pack, such as an increased self-discharge rate of the battery pack or an increased balancing requirement, may also result in: the inspection process and the subsequent process are performed again. In the case of the next inspection process that is performed again, the next time period is specified. The next time period can be different from the first time period individually, especially shorter or longer. For the length of the next time period or multiple time periods, in particular, the state of the battery pack can be decisive: if thermal runaway is about to occur or already exists (for example, in a form that does not mean direct danger), a short time period can be selected. Another temperature value can be used (and in most cases in practice) as the target temperature value. Despite the use of the same evaluation criteria, another choice may still be made.

[0053] In particular, when thermal runaway is detected, a signal is output. In this regard, a control unit, in particular the computing and control device, can be activated or reactivated, by means of which the method is performed. In particular, the signal can be output when a danger (e.g., explosion, fire) is imminent. The signal can be, in particular, an optical or acoustic signal. The signal can be output, for example, within a motor vehicle and / or output to the outside. The signal can be, for example, a display in a display and / or a signal of a horn and / or a warning flash function. Alternatively or additionally, the signal can be output to another device, in particular a smart phone or a computer, for example, by means of a wireless data connection, such as a mobile radio connection or a wireless network connection. In this way, the signal can be notified to an external person or an external device, such as a manufacturer of a motor vehicle or a national authority. Alternatively or additionally, the output of the signal can be or include the output of the corresponding electronic data by means of the computing and control device.

[0054] Before the occurrence of thermal runaway and / or the output of the signal, at least one control unit of the motor vehicle, in particular the computing and control device, can be activated or reactivated, by means of which the method is performed. The at least one control unit, in particular the computing and control device, by means of which the method is performed, can be designed to trigger at least one other additional measure within the motor vehicle in this case. Such other additional measures can be implemented in particular when an imminent or imminent thermal runaway is not excluded or is assumed to occur, for example when there is no immediate danger (e.g. explosion, fire) but a critical state of the battery pack has occurred, such as a temperature or temperature difference or power loss that is out of or exceeds a specified range or a predetermined threshold value and / or other irrationality of the battery pack. The other additional measures can in particular be or include the activation of a cooling function, in particular a cooling function involving the battery pack.

[0055] It is also conceivable that other data or parameters related to the method, such as temperature intervals or checking processes, are communicated to personnel, or such data or parameters are sent to an external computer, such as a server in a network. The information obtained thereby, such as optimized or updated target temperature values, evaluation criteria or optimized or updated temperature models, can in turn be sent to the motor vehicle and in particular to the computing and control device for use.

[0056] It is not excluded that information is output, especially automatically, when the next inspection process and the next subsequent process are performed in the subsequent process. The information may be, for example, warning information, such as the lighting of a warning light, and / or status information, which indicates information about the status of the battery pack and / or the vehicle.

[0057] In particular, no further measures may be taken when thermal runaway can be ruled out.

[0058] The method described can be implemented at least to a large extent or completely with the aid of existing hardware, in particular such hardware relating to control and / or battery management and / or active balancing of the battery pack. In this way, only or almost only adaptations on the software side are necessary. The method is inexpensive and simple to implement.

[0059] Thermal runaway or imminent thermal runaway of a battery pack in a motor vehicle can be particularly reliably detected, since the method can detect, in particular, when the motor vehicle is parked, stopped, or not in use, which may have been parked, stopped, or not in use for a longer period of time, for example, several hours or days. In particular, fires caused by unattended motor vehicles, for example in garages or parking lots, or fires that could spread to other objects / buildings / properties can be avoided.

[0060] In particular, since the motor vehicle can be in a sleep mode during these time periods, in particular, the energy consumption for monitoring can be very small. Typical time periods can be in the order of 30, 45 or 60 minutes. However, longer or shorter time periods are also possible. The software required for carrying out the method can be easily updated, for example by means of a wireless connection.

[0061] In one embodiment, the battery pack is operated according to the operating mode and / or the charging process before the operation or the charging process is completed.

[0062] -Charging method

[0063] and / or according to

[0064] -Battery pack temperature and / or

[0065] - the value of the temperature difference between two locations in the battery and / or

[0066] - Ambient temperature value and / or

[0067] -Power loss value of the battery pack

[0068] to define this time period.

[0069] The mentioned value or at least one of the mentioned values ​​can be recorded in particular at a time when the operation or the charging process ends or at a time before or after the end, for example at a time that specifies the time period.

[0070] The operating mode can be, in particular, the power output of the battery pack during traction operation, in particular during driving operation of the motor vehicle. In particular, a distinction can be made based on the load to which the battery pack is subjected due to the driving operation. If, for example, the vehicle has already been driven at high speed and / or high acceleration shortly before the end of the operation, the battery pack can have a relatively high temperature and / or a relatively high temperature difference, in particular due to the high power output. Correspondingly, the time period can be adapted. In particular, the time period can be relatively short in this case, for example half an hour. The subsequent time period can also be relatively short, in particular shorter than the (first) time period and / or become increasingly shorter or longer.

[0071] If, however, the driving operation is characterized by a low power output, the battery pack may have a relatively low temperature and / or a relatively low temperature difference. In this case, the time period can be adapted. The time period can be particularly long, for example one hour. The subsequent next time period can also be relatively long, in particular longer than the (first) time period and / or become increasingly longer or shorter. The corresponding situation applies to the charging process: a charging process with high electrical power (e.g. charging with a DC voltage) may result in high temperatures or high temperature differences. The time period can be relatively short. The subsequent next time period can also be relatively short, in particular shorter than the (first) time period and / or become increasingly shorter or longer. In the case of charging with low electrical power, the time period can be relatively long. The subsequent next time period can also be relatively long, in particular longer than the (first) time period and / or become increasingly longer or shorter.

[0072] In addition, high temperature values ​​of the battery pack and / or an absolutely high temperature difference at two locations in the battery pack can lead to the provision of a relatively short time period. The subsequent next time period can also be relatively short, in particular shorter than the (first) time period and / or become increasingly shorter or longer. Low temperature values / absolute low temperature differences can lead to the provision of a relatively long time period. The subsequent next time period can also be relatively long, in particular longer than the (first) time period and / or become increasingly longer or shorter. It is possible that the value of the power loss of the battery pack is also taken into account when specifying the time period. High power loss can in particular lead to the provision of a relatively short time period. The subsequent next time period can also be relatively short, in particular shorter than the (first) time period and / or become increasingly shorter or longer.

[0073] Likewise, ambient temperature values ​​(in particular ambient temperature values ​​at the current time and / or at the time of the end of the operation or the charging process) can be used. A high ambient temperature that reduces the cooling of the battery pack can in particular lead to the provision of a shorter time period. The subsequent next time period can also be shorter, in particular shorter than the (first) time period and / or become shorter or longer. A low ambient temperature can in particular lead to the provision of a longer time period. The subsequent next time period can also be longer, in particular longer than the (first) time period and / or become longer or shorter.

[0074] The computing and control device can be designed to determine and prescribe the time period with the aid of a model, which can be, in particular, an empirical, numerical or analytical model. In particular, an interface or exchange with a temperature model can be present or carried out. The temperature model itself can have the function of prescribing the time period and be used for this. The computing and control device can be designed to record, with the aid of corresponding devices, for example corresponding sensors, which operating mode and / or which charging mode is / was present before the operation or the charging process is terminated.

[0075] The described embodiment provides a particularly simple possibility of defining the time period. Furthermore, the operating mode and the charging mode as well as the values ​​mentioned are each highly convincing, which in particular leads to a reliable determination of a suitable time period. In particular, a time period that is not selected to be too short can, on average, reduce the energy consumption per unit time.

[0076] In one embodiment, the temperature of the battery pack and / or the

[0077] - the value of the temperature difference between two locations in the battery and / or

[0078] - Ambient temperature value and / or

[0079] -Power loss value of the battery pack

[0080] To specify at least one next time period.

[0081] The remarks about the (first) time period apply correspondingly. In addition, it is not excluded that previously recorded values, for example values ​​recorded at the time of the end of the operation or the charging process, are taken into account when defining the next time period. It is also not excluded that the operating mode and / or

[0082] -Charging method

[0083] If at least one next time period is mentioned, this means, if there are a plurality of subsequent time periods, that each subsequent time period can be determined individually. Otherwise, the advantages mentioned with respect to the (first) time period apply correspondingly.

[0084] In one embodiment, the following values ​​are used as input parameters in the temperature model:

[0085] - a value of a temperature difference between two locations in the battery pack at a time point at which the operation or the charging process ends or at a time point before the operation or the charging process ends;

[0086] a temperature value in the battery pack at the time of the end of the operation or the charging process or at a time before the end of the operation or the charging process.

[0087] These values ​​can be used in particular in the temperature model to determine corresponding target values. The current value of the temperature difference at two locations in the battery pack and the current temperature value in the battery pack can then be compared with these target values. A choice about the subsequent process can then be made based on the result of the comparison.

[0088] In this regard, it should be mentioned that, in general, and without being limited to the embodiments described, it is not excluded that the evaluation criteria allow for the consideration of multiple input values, such as temperature differences and temperature values. It is also not excluded that multiple evaluation criteria are used. In particular, a single selection can still be made.

[0089] Starting from the values ​​of the temperature difference and the temperature value at the time of the end of the operation or the charging process or at the time before the end of the operation or the charging process, one or more time profiles can be presented, in particular, taking into account one or more corresponding current values. In particular, these time profiles can be compared with target profiles. It is also possible to carry out predictions and / or extrapolations and compare these predictions and / or extrapolations with one another and take them into account when making a selection.

[0090] The embodiment described is a simple embodiment based on a convincing database. The expenditure on sensors, hardware and computing technology is low. The energy consumption and the costs required for implementation are also low.

[0091] In one specific embodiment, during this time period and / or during at least one next time period, a computing and control device of the motor vehicle used to perform the method is switched off and / or is in standby mode and / or the motor vehicle is put into sleep mode.

[0092] This prevents the battery from being discharged during this time period and / or during one or more subsequent time periods, or reduces the discharge of the battery. Energy consumption is low. In particular, other, almost all or all computing and / or control units and / or other electrical consumers of the motor vehicle can be switched off or put into standby mode. This mode can also be referred to as a sleep mode. The sleep mode can be used in particular when the motor vehicle is parked or stopped.

[0093] In one embodiment, the computing and control device and / or the motor vehicle are reactivated from the sleep mode by means of an electronic circuit, which is designed for time measurement. The circuit can be connected to the computing and control device. The circuit can be designed in particular for measuring a time period. The circuit can be designed to emit an activation signal after the expiration of the time period. The circuit can in particular have a timer. The circuit can have its own energy storage, for example a battery. Alternatively or additionally, the circuit can be connected to a battery pack of the motor vehicle for the purpose of energy supply.

[0094] The described embodiment reduces the energy consumption of the motor vehicle during the application of the described method. In addition, it is simple to implement. The hardware technology expenditure is low. The cost is also low.

[0095] A motor vehicle, in particular a motor vehicle with an electric drive or a hybrid electric drive, is also proposed, which has:

[0096] -Battery pack;

[0097] - a computing and control device, which is designed to

[0098] After the operation or charging process of the battery pack has ended, a check process is performed, in which a time period is specified and after the expiration of the time period a comparison of a temperature value of the battery pack with a target temperature value is performed, wherein the target temperature value is determined with the aid of a temperature model that describes a target cooling of the battery pack, and a selection is made with the aid of a result of the comparison with the aid of a predefined evaluation criterion, so that in a subsequent process that the computing and control device is designed to perform, either the check process is performed again as a next check process, in which a next time period is specified in the case of the next check process and after the expiration of the next time period a next comparison of a next temperature value of the battery pack with a next target temperature value determined with the aid of the temperature model is performed, and a next selection is made with the aid of the result of the next comparison with the aid of the evaluation criterion, wherein the subsequent process is performed again as a next subsequent process according to the next selection, and either a signal is output or no further measures are taken;

[0099] - an output device, which is designed to output the signal, wherein the output device is connected to the computing and control device; - at least one temperature sensor, which is designed to measure the temperature of the battery pack, wherein the temperature sensor is connected to the computing and control device.

[0100] The motor vehicle can be designed in particular for implementing the method described. The above comments apply accordingly. The computing and control device can be implemented in particular as a control device and / or a computer or can include such a control device / such a computer. The output device can be designed in particular so that the output device can output an optical, tactile or acoustic signal to a person located in the motor vehicle or outside the motor vehicle, for example, nearby. It can especially be related to a warning signal. The output device can also be designed so that the output device outputs a signal to other devices via an interface. The signal can also be transferred to another device, such as a server or a smart phone, by means of a wireless connection, in particular a mobile radio or a wireless network connection.

[0101] With regard to other design solutions, reference is made to the above description of the method. BRIEF DESCRIPTION OF THE DRAWINGS

[0102] The invention is explained in more detail below with reference to an exemplary embodiment of the method according to the invention and an exemplary embodiment of the motor vehicle according to the invention.

[0103] Figure 1 A schematic diagram of a design scheme of the method according to the present invention is shown;

[0104] Figure 2 A schematic diagram of an embodiment of a motor vehicle according to the invention is shown.

[0105] For identical, functionally identical or similar parts / components / steps / values / information / facts or areas, the same reference signs are used. DETAILED DESCRIPTION

[0106] exist Figure 1 A schematic diagram of the design of the method according to the present invention is shown in FIG. Figure 2 ) of the battery pack 3. Figure 1 1 is schematically shown by a plug on the battery pack 3, which is separated from the schematically shown charging station. Alternatively, another operation of the battery pack 3, in particular in the form of power output when the motor vehicle 1 is driving, can also be terminated. The battery pack 3 can be a traction battery in particular. The battery pack can be an electrochemical battery, for example a lithium-ion battery. The motor vehicle can be a motor vehicle with an electric drive or a hybrid electric drive in particular.

[0107] In a second step S2, the calculation and control device 2 (see Figure 2 ) to determine the time period ZI. The time period ZI can be, for example, forty-five minutes. For this determination, information LA about the charging method of the battery pack 3 of the motor vehicle 1 is used. Before the end of the charging process, the battery pack 3 is charged, for example, by direct voltage charging at a high charging power.

[0108] The value of the ambient temperature TU is also used, which is recorded, for example, by means of a corresponding sensor. In addition, the value TDB of the maximum temperature difference in the battery pack 3 at the time when the charging process ends is used. The value of the maximum temperature difference is determined by means of sensors at the battery pack 3 and by means of the calculation and control device 2. These sensors can be, for example, sensors SE1, SE2, SE3 and SE4 (see third step S3). In addition, the average temperature TMB in the battery pack 3 at the time when the charging process ends is used. This average temperature is again determined by means of sensors at the battery pack 3 and the calculation and control device 2. These sensors can be, for example, sensors SE1, SE2, SE3 and SE4.

[0109] Time period ZI expires. Figure 1, which is schematically shown by a rounded rectangle symbol, which contains the reference symbol "ZI" for the time period ZI and arrows above and below this reference symbol. In this case, the computing and control device 2 can be switched off or in standby mode. Other control units of the motor vehicle 1 can also be switched off or in standby mode. The motor vehicle 1 can in particular be put into sleep mode. After the end of the time period ZI, the computing and control device 2 can be reactivated and, if necessary, other control units can be switched on again and, if necessary, the sleep mode can be ended. This can be done with the aid of an activation circuit 4. This is shown by the arrows of the reference symbol 4. Figure 1 The activation circuit 4 can be designed in particular for time measurement.

[0110] In a third step S3, the value TDA of the maximum temperature difference and the temperature mean TMA in the battery 3 at a point in time after the expiration of the time period ZI are determined. This can be achieved in particular using the computing and control device 2. The temperature values ​​T1, T2, T3, T4 measured at a plurality of locations in the battery 3 (e.g. different battery cells or battery blocks or modules or battery stacks or clusters) by means of temperature sensors SE1, SE2, SE3, SE4 can be used. This is Figure 1 This is schematically illustrated in FIG. 1 by means of corresponding illustrations of temperature sensors SE1 , SE2 , SE3 , SE4 and arrows originating therefrom.

[0111] In a fourth step S4, the value TDA of the maximum temperature difference (at a time point after the expiration of the time period ZI) is compared with the corresponding target value and the mean temperature TMA (at a time point after the expiration of the time period ZI) is compared with the corresponding target value. This can be achieved in particular using the calculation and control device 2.

[0112] The target values ​​mentioned are a target value TDS for the maximum temperature difference in the battery pack 3 at a point in time after expiration of the time period ZI and a target mean temperature value TMS in the battery pack 3 at a point in time after expiration of the time period ZI.

[0113] The target values ​​mentioned are determined with the aid of a temperature model TMO. In the temperature model TMO, in particular the value TDB of the maximum temperature difference in the battery pack 3 (at the time of the end of the charging process) and the mean temperature TMB in the battery pack 3 (at the time of the end of the charging process) are taken into account. Other variables and parameters, such as ambient temperature values ​​or geometric or physical parameters of the battery pack 3, may also be taken into account.

[0114] The result of the comparison, i.e. the first result E1 and the second result E2, can be determined, for example, by means of a difference between the actual value and the target value. In the fifth step S5, a selection A is made based on the first result E1 and the second result E2, using an evaluation criterion BK, which allows a particularly common evaluation of the two results E1 and E2. The evaluation criterion BK can have an interval and a threshold value in particular. If the first result or the second result is in a respectively corresponding interval, a corresponding selection is made. In particular, in the case of a certain difference between the actual value and the target value, for example, either the inspection process is performed again as the next inspection process and the subsequent process is performed again as the next subsequent process, or a signal, in particular an alarm signal, is output when these differences are, for example, large. For this purpose, a calculation and control device 2 can be used in particular. In the case of a small difference between the actual value and the target value, no other measures can be taken as a subsequent process.

[0115] The steps from the second step S2 to the fifth step S5 are referred to as the inspection process. The sixth step S6 and the seventh step in any variant (S7-1, S7-2, S7-3) are referred to as the subsequent process.

[0116] Option A describes what actions are chosen as follow-up procedures. Figure 1 In the example, the start of the subsequent process is symbolically represented by the sixth step S6. There are three variants of how the subsequent process can be implemented, which are presented as three different seventh steps S7-1, S7-2, S7-3. Either output a signal (seventh step [first variant] S7-1), in particular using the output device 5 ( Figure 2 ) to output a signal, either no other measures are taken (seventh step [second variant] S7-2), or the inspection process is executed again, that is, the next inspection process, and the subsequent process is executed again, that is, the next subsequent process (seventh step [third variant] S7-3).

[0117] In the case of the next inspection process, the next time period is specified, the next comparison of the temperature value of the battery pack 3 with the target temperature value is performed, and the next selection is made. In the case of the next subsequent process, one of the three steps mentioned is implemented again (output a signal; do not take other measures; or perform the inspection process again, that is, the next inspection process, and perform the subsequent process again, that is, the next subsequent process).

[0118] In this way, a sequence of time periods can be obtained as a result, after which the next comparison of the temperature value of the battery pack 3 with the target temperature value is respectively performed and the next selection is made. The checking process and the subsequent process can be respectively performed again in sequence one or more times with the corresponding next selection as a prerequisite. The sequence can be ended by selecting a subsequent process in which a signal is output or no other measures are taken.

[0119] exist Figure 2 In FIG. 1 , a motor vehicle 1 according to the invention is shown very schematically.

[0120] The motor vehicle has a battery pack 3, which can be mounted in particular on the vehicle floor. The battery pack 3 can be in particular a traction battery pack of the motor vehicle 1. The battery pack can be in particular an electrochemical battery pack, in particular a lithium-ion battery pack. The motor vehicle also has a computing and control device 2, which is connected to four temperature sensors SE1, SE2, SE3 and SE4 via cables. Alternatively or additionally, a wireless connection (for example a mobile radio or WLAN) or an indirect connection, for example via another device, is also possible, which then forwards the measured temperature value to the computing and control device 2. The motor vehicle 1 also has an output device 5, which can be part of the computing and control device 2. The output device 5 can be designed to output a human-perceptible signal, in particular an optical or acoustic signal. The output device can also be designed to output a signal to another device, for example a computer, a server or a smartphone. The vehicle has an activation circuit 4, which is connected to the computing and control device 2. The activation circuit is designed to reactivate the computing and control device 2 after the expiration of a time period or a subsequent time period.

[0121] The motor vehicle 1 can be designed in particular to carry out the described embodiment of the method according to the invention. The remarks made thereon therefore apply correspondingly.

[0122] Reference numerals list

[0123] S1 Step 1: End the charging process of the battery pack

[0124] S2 Step 2: Specify the time period

[0125] ZI time period

[0126] S3 Step 3: Determine the average temperature and maximum temperature difference in the battery pack

[0127] S4 Step 4: Compare the average temperature and the maximum temperature difference with the corresponding target values

[0128] S5 Step 5: Selection based on predefined evaluation criteria

[0129] S6 Step 6: Start the follow-up process

[0130] S7-1 Step 7 (First Variant): Output Signal

[0131] S7-2 Step 7 (Second Variant): No other measures are taken

[0132] S7-3 Seventh step (third variant): re-execute the inspection process and subsequent processes

[0133] LA Information on how to charge the battery pack

[0134] TU Ambient temperature

[0135] TDB (time point at which the charging process ends) is the value of the maximum temperature difference in the battery pack

[0136] TMB (time point at which the charging process ends) is the average temperature in the battery pack

[0137] SE1 Temperature Sensor

[0138] SE2 Temperature Sensor

[0139] SE3 Temperature Sensor

[0140] SE4 Temperature Sensor

[0141] T1 temperature value

[0142] T2 temperature value

[0143] T3 temperature value

[0144] T4 temperature value

[0145] ZI time period

[0146] TDA (at a point in time after the time period has expired) is the value of the maximum temperature difference in the battery pack

[0147] TMA (time point after the time period has expired) is the average temperature in the battery pack

[0148] TMO Temperature Model

[0149] TDS (at a point in time after the time period has expired) Target value of the maximum temperature difference in the battery pack

[0150] TMS (at a point in time after the time period has expired) is the target temperature average value in the battery pack

[0151] E1 First Result

[0152] E2 Second result

[0153] A Selection

[0154] 3. Battery Pack

[0155] 1 Motor Vehicle

[0156] 2 Computing and control devices

[0157] 4 Activation Circuit

[0158] 5 Output Devices

[0159] BK Evaluation Criteria

Claims

1. A method for detecting thermal runaway in a battery (3) of a motor vehicle (1), wherein a check process is performed after the end of an operation or charging process of the battery (3), in which a time period (ZI) is specified and after the expiration of the time period (ZI), a comparison of temperature values ​​(T1, T2, T3, T4, TDA, TMA) of the battery (3) with target temperature values ​​(TDS, TMS) is performed, wherein the target temperature values ​​(TDS, TMS) are determined with the aid of a temperature model (TMO) describing a target cooling of the battery (3), and a selection (A) is made with the aid of a result (E1, E2) of the comparison with the aid of a predefined evaluation criterion (BK), so that in a subsequent process, either - the checking process is performed again as a next checking process, wherein in the case of the next checking process a next time period is specified and after expiration of the next time period a next comparison of a next temperature value of the battery pack (3) with a next target temperature value determined by means of the temperature model (TMO) is performed, and a next selection is made by means of the result of the next comparison by means of the evaluation criterion (BK), wherein the subsequent process is performed again as a next subsequent process according to the next selection; or - output signal; or - No other measures are taken, wherein the battery pack (3) is operated and / or charged according to the operating mode and / or -Charging method and / or according to - temperature values ​​(TDB, TMB) of the battery pack (3) and / or - the value of the temperature difference (TDB) between two locations in the battery (3) and / or - Ambient temperature (TU) and / or - the value of the power loss of the battery pack (3) to define the time period (ZI), in, The next time period is determined separately and independently of the time period (ZI). 2 . The method according to claim 1 , wherein the motor vehicle ( 1 ) is a motor vehicle with an electric drive or a hybrid electric drive.

3. The method according to claim 1 or 2, wherein the temperature of the battery pack (3) and / or - the value of the temperature difference between two locations in the battery (3) and / or - Ambient temperature (TU) and / or - the power loss value of the battery pack (3) To specify at least one next time period.

4. The method according to claim 1 or 2, wherein the following values ​​are used as input variables in the temperature model (TMO): - a value (TDB) of a temperature difference between two locations in the battery pack (3) at a time point at which the operation or the charging process ends or at a time point before the operation or the charging process ends; a temperature value (TMB) in the battery (3) at a time point in time at which the operation or the charging process ends or at a time point before the operation or the charging process ends.

5. A method according to claim 1 or 2, wherein during the time period (ZI) and / or during at least one next time period, a computing and control device (2) of the motor vehicle (1) used to execute the method is switched off and / or is in standby mode, and / or the motor vehicle (1) is placed in sleep mode.

6. The method according to claim 5, wherein the computing and control device (2) and / or the motor vehicle (1) is reactivated from the sleep mode by means of an electronic circuit which is designed for time measurement.

7. A motor vehicle (1), comprising: - a battery pack (3); - a computing and control device (2) which is designed to: perform a check process after the end of the operation or charging process of the battery pack (3), in which a time period (ZI) is specified and after the expiration of the time period (ZI) a comparison of the temperature values ​​(T1, T2, T3, T4, TDA, TMA) of the battery pack (3) with target temperature values ​​(TDS, TMS) is performed, wherein the target temperature values ​​(TDS, TMS) are determined with the help of a temperature model (TMO) describing the target cooling of the battery pack (3), and the result of the comparison (E1, E2) is used to determine the target temperature value (TDS, TMS) with the help of a predefined evaluation criterion ( BK) to make a selection (A) so that in a subsequent process that the computing and control device (2) is designed to perform, either the checking process is performed again as a next checking process, wherein in the case of the next checking process a next time period is specified and after expiration of the next time period a next comparison of a next temperature value of the battery pack (3) with a next target temperature value determined by means of the temperature model (TMO) is performed, and a next selection is made by means of the result of the next comparison by means of the evaluation criterion (BK), wherein the subsequent process is performed again as a next subsequent process according to the next selection, and either a signal is output or no further measures are taken; - an output device (5), which is designed to output the signal, wherein the output device (5) is connected to the calculation and control device (2); at least one temperature sensor, which is designed to measure the temperature of the battery (3), wherein the temperature sensor is connected to the computing and control device (2), The computing and control device (2) is designed to: according to the operating mode and / or the charging process of the battery pack (3) before the operation or the charging process ends -Charging method and / or according to - temperature values ​​(TDB, TMB) of the battery pack (3) and / or - the value of the temperature difference (TDB) between two locations in the battery (3) and / or - Ambient temperature (TU) and / or - the power loss value of the battery pack (3) to define the time period (ZI), Therein, the next time period is determined separately and independently of the time period (ZI).

8. The motor vehicle (1) according to claim 7, wherein the motor vehicle (1) is a motor vehicle with an electric drive or a hybrid electric drive.

9. The motor vehicle (1) according to claim 7 or 8, wherein the computing and control device (2) is designed to: determine the temperature of the battery pack (3) and / or the temperature of the battery pack (3) at a time point that specifies the next time period; - the value of the temperature difference between two locations in the battery (3) and / or - Ambient temperature (TU) and / or - the power loss value of the battery pack (3) To specify at least one next time period.

10. The motor vehicle (1) according to claim 7 or 8, wherein the calculation and control device (2) is designed such that the following values ​​are used as input variables in the temperature model (TMO): - a value (TDB) of a temperature difference between two locations in the battery pack (3) at a time point at which the operation or the charging process ends or at a time point before the operation or the charging process ends; a temperature value (TMB) in the battery (3) at a time point in time at which the operation or the charging process ends or at a time point before the operation or the charging process ends.

11. A motor vehicle (1) according to claim 7 or 8, wherein the motor vehicle (1) is designed so that during the time period (ZI) and / or during at least one next time period, the computing and control device (2) is switched off and / or is in standby mode, and / or the motor vehicle (1) is placed in sleep mode.

12. A motor vehicle (1) according to claim 11, wherein the motor vehicle (1) has an electronic circuit which is designed for time measurement and is also designed to: trigger reactivation of the computing and control device (2) and / or reactivation of the motor vehicle (1) from the sleep mode.

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