DE102020208556B4 - Thermal runaway detection method and motor vehicle - Google Patents

Abstract

The invention relates to a method for detecting thermal runaway in a battery (3) of a motor vehicle (1), in particular a motor vehicle (1) with an electric or hybrid-electric drive, after termination of operation or charging of the battery (3) a checking process is carried out, in which a time interval (ZI) is defined and after the time interval (ZI) has elapsed, a temperature value (T1, T2, T3, T4, TDA, TMA) of the battery (3) is compared with a target temperature value ( TDS, TMS) is carried out, the target temperature value (TDS, TMS) using a temperature model (TMO), which describes a target cooling of the battery (3), is determined, and using the result (E1, E2) of the comparison a selection (A) is made using a predefined assessment criterion (BK) in such a way that in a subsequent process either the verification process is carried out again as a further verification process ird, wherein a further time interval is defined during the further checking process and after the further time interval has elapsed, a further comparison of a further temperature value of the battery (3) with a further target temperature value determined using the temperature model (TMO) is carried out and using the result the further comparison, a further selection is made using the assessment criterion (BK), the follow-up process being carried out again as a further follow-up process depending on the further selection; or- a signal is output; or no further action is taken. Furthermore, the invention relates to a corresponding motor vehicle.

Description

The invention relates to a method for detecting a thermal runaway in a battery of a motor vehicle and a motor vehicle configured to detect a thermal runaway.

In motor vehicles, in particular those with an electric or hybrid electric drive, there is a risk that a battery, in particular a drive battery, will experience thermal runaway, ie an uncontrolled and undesired thermal reaction in the form of heating. Such a thermal runaway can occur in particular with lithium-ion batteries, such as are frequently used as traction batteries in motor vehicles with electric or hybrid electric drives. The consequences can be, in particular, a fire and/or an explosion. It is therefore important that a motor vehicle user is prompted to leave the motor vehicle while using the motor vehicle by means of a suitable warning in the event of a thermal runaway.

Safety requirements for batteries in motor vehicles with electric or hybrid electric drives are specified in various standards, guidelines and regulations. In this context, for example, the national standard of the People's Republic of China "Electrical Vehicles Traction Battery Safety Requirements" should be mentioned. This standard is issued by the General Administration of Quality Supervision, Inspection and Quarantine (“AQSIQ”) and the Standardization Administration of China (Chinesisches Amt for standardization"). In particular, the national standard defines safety requirements and specifications for safety tests of traction batteries. In Europe, the UNECE R 100 regulation will also be important in the future.

• - Erhalten von detektierten Spannungswerten von mehreren Spannungserfassungspunkten in einer Batterie und von mehreren detektierten Temperaturwerten an jeweils mehreren Temperaturerfassungspunkten in der Batterie;
• - Berechnen der Temperaturanstiegsrate der Batterie auf Grundlage der detektierten Temperaturwerte.
• - Bestimmen, ob die Batterie ein thermisches Durchgehen erleidet, basierend auf mehreren detektierten Spannungswerten, mehreren detektierten Temperaturwerten und der Temperaturanstiegsrate.

CN 110 068 768 A discloses a method for detecting a thermal runaway of a battery, the method comprising:

• - obtaining detected voltage values from a plurality of voltage sensing points in a battery and a plurality of detected temperature values at a plurality of temperature sensing points in the battery, respectively;
• - Calculating the temperature rise rate of the battery based on the detected temperature values.
• - Determining whether the battery is suffering from a thermal runaway based on a plurality of detected voltage values, a plurality of detected temperature values and the rate of temperature increase.

• - drahtloses Empfangen von Temperaturmessdaten von einem einzelnen Monoblock oder einer Vielzahl von Monoblöcken, die elektrisch in Reihe oder parallel geschaltet sind, wobei die Temperaturmessdaten die Temperaturen innerhalb von jedem der Vielzahl von Monoblöcken darstellen;
• - Berechnen eines Temperaturwertes, der gleich einem Mittelwert der Temperaturmessdaten ist, die drahtlos von allen Monoblöcken der Vielzahl von Monoblöcken in einer Batterie empfangen werden;
• - Berechnen einer hohen Temperaturdifferenz als Absolutwert der Differenz zwischen der höchsten Monoblock-Temperatur in der Batterie und dem Temperaturwert;
• - Berechnen einer niedrigen Temperaturdifferenz als Absolutwert der Differenz zwischen der niedrigsten Monoblock-Temperatur in der Batterie und dem Temperaturwert; und Auslösen eines Alarms, wenn die hohe Temperaturdifferenz größer als eine vorbestimmte hohe Temperaturschwelle ist oder wenn die niedrige Temperaturdifferenz größer als eine vorbestimmte niedrige Temperaturschwelle ist.

U.S. 2019/0 036 178 A1 discloses a method for monitoring battery temperature and providing alerts of abnormal temperatures, comprising:

• - wirelessly receiving temperature measurement data from a single monoblock or a plurality of monoblocks electrically connected in series or parallel, the temperature measurement data representing the temperatures within each of the plurality of monoblocks;
• - calculating a temperature value equal to an average of the temperature measurement data wirelessly received from all monoblocks of the plurality of monoblocks in a battery;
• - calculating a high temperature difference as an absolute value of the difference between the highest monobloc temperature in the battery and the temperature value;
• - calculating a low temperature difference as an absolute value of the difference between the lowest monobloc temperature in the battery and the 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.

CN 107 611 513 A discloses a method for detecting thermal runaway of a lithium-ion battery in an electric vehicle, wherein a lithium-ion battery management system or BMS system for an electric vehicle is disclosed that monitors the voltage and temperature of each cell of the battery.

From the EP 3 657 594 A1 a device for detecting a thermal runaway of a battery module with a plurality of cells is known, comprising a current detection module configured to detect a set of currents and a temperature detection module configured to detect a set of temperatures, and a state of charge acquisition module configured to acquire a set of states, and a resistance calculation module configured to derive a set of resistances, and a temperature prediction module configured to calculate a set of temperature predictors, and a through hen prediction engine configured to: a. to calculate a set of runaway predictors and a warning module configured to set a warning indicator in the event that at least one runaway predictor value of the set of runaway predictors exceeds a predefined threshold.

The invention is based on the technical problem of more reliably detecting a thermal runaway or an impending thermal runaway of batteries in motor vehicles. Another technical problem is to reduce the power consumption incurred by monitoring a battery to detect thermal runaway or impending thermal runaway. A further technical problem lies in realizing a detection of the thermal runaway or the imminent thermal runaway with little outlay on hardware and in an inexpensive and simple manner.

According to a basic idea of the present invention, a temperature value of the battery is checked in such a way that this temperature value is compared with a target temperature value determined by a temperature model. Such a comparison takes place after a time interval has elapsed, the time interval starting to run after an operation or a charging process of the battery has ended. In particular, the time interval can begin to run immediately after the operation or the charging process of the battery has ended. It may alternatively start running at a time interval, which may be predefined, after the battery has stopped operating or charging.

In particular, the operation can be a driving operation of the motor vehicle in which the battery was used. The charging process can in particular be a quick charging process. In such processes, the battery can be exposed to high thermal stresses. This can increase the likelihood of thermal runaway. The battery can in particular be the traction battery of the motor vehicle.

In particular, after the end of operation, the motor vehicle can be switched off, in particular parked, and/or locked. In particular, the so-called ignition of the electric vehicle can be switched off. In particular, a low-voltage circuit of the motor vehicle may be turned off (e.g., a 12V or 48V circuit) or have only a small current flowing in it. In particular, a high-voltage circuit (in particular a traction circuit and/or a 400V or 800V circuit) of the motor vehicle can also be switched off or only a small current can flow in it.

Temperature values can be determined at least once, but also several times, in particular several times at time intervals. There are time intervals between the end of the operation or the charging process and the first determination of a temperature value and between the first determination and any further determinations, a time interval at the beginning and possibly further time intervals thereafter. A further time interval can in particular be shorter than the time interval at the beginning. Subsequent further time intervals can also be shorter than the time interval at the beginning or can become increasingly shorter. Shorter intervals provide an opportunity to more quickly identify a thermal runaway or respond quickly to a developing or imminent thermal runaway.

A further time interval can in particular also be longer than the time interval at the beginning. Subsequent further time intervals can also be longer than the time interval at the beginning or can become increasingly longer. Longer intervals provide a good opportunity to detect thermal runaway and monitor the battery with low power consumption.

Based on the respective result of the comparison of a temperature value or an additional temperature value with a target temperature value or an additional target temperature value, a selection for a subsequent measure is made using a predefined assessment criterion. This results in the sequence whether the checking process is carried out again, i.e. a further checking process is carried out (including renewed determination of a further time interval, new comparison, new selection made with a corresponding sequence) or a signal is output, or no further action is taken. The signal can in particular be a warning signal.

If no further action is taken, this means that, in particular, no further review will be carried out. This can be the case if the result of the comparison leads to an assessment that no thermal runaway is assumed. If a thermal runaway is assumed on the basis of the result of the comparison, the signal can in particular be output, in particular when danger is imminent. In particular, if a thermal runaway appears possible, soon possible, or is there a risk of a ther mixed runaway, another check is performed. This is also possible if there is already a thermal runaway, but no immediate danger (e.g. risk of fire or explosion) emanates from it.

• - der Überprüfungsvorgang als weiterer Überprüfungsvorgang erneut durchgeführt wird, wobei bei dem weiteren Überprüfungsvorgang ein weiteres zeitliches Intervall festgelegt wird und nach Ablauf des weiteren zeitlichen Intervalls ein weiterer Vergleich eines weiteren Temperaturwerts der Batterie mit einem mithilfe des Temperaturmodells bestimmten weiteren Soll-Temperaturwert durchgeführt wird und mithilfe des Ergebnisses des weiteren Vergleichs eine weitere Auswahl mithilfe des Beurteilungskriteriums getroffen wird, wobei der Folgevorgang als weiterer Folgevorgang abhängig von der weiteren Auswahl erneut durchgeführt wird; oder
• - ein Signal ausgegeben wird; oder
• - keine weitere Maßnahme ergriffen wird.

In particular, a method is proposed for detecting thermal runaway in a battery of a motor vehicle, in particular a motor vehicle with an electric or hybrid-electric drive, after the end of an operation or a charging process of the battery, a checking process is carried out, in which a time interval is defined and after At the end of the time interval, a temperature value of the battery is compared with a target temperature value, the target temperature value being determined using a temperature model that describes a target cooling of the battery, and using the result of the comparison to make a selection using a predefined one Assessment criterion is taken such that in a subsequent process either

• - the checking process is carried out again as a further checking process, with a further time interval being defined in the further checking process and after the further time interval has elapsed, a further comparison of a further temperature value of the battery with a further target temperature value determined using the temperature model is carried out and with the aid of the result of the further comparison, a further selection is made using the assessment criterion, the follow-up process being carried out again as a further follow-up process depending on the further selection; or
• - a signal is issued; or
• - no further action is taken.

The battery can in particular be an electrochemical energy store. In particular, it can be a lithium-ion battery. In particular, it can serve as a traction battery for the motor vehicle. It can also serve as an auxiliary traction battery, for example in a motor vehicle with a hybrid electric drive.

The checking process starts at a point of time after the operation or charging is finished. The checking process can follow immediately after the operation or the loading process. In particular, it can also be triggered when the motor vehicle is switched off, parked or locked, or at a time interval after this process. In particular, this interval can be short, for example a few (e.g. 1 to 10) minutes.

The method can be carried out in particular with the aid of a computing and control device in the motor vehicle. The method can be carried out in particular partially or fully automatically. The computing and control device can in particular have a computing unit, a memory, a main 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 cellular connection or via a wireless network. It is possible for at least one part or step of the method to be outsourced to a computer located outside the motor vehicle, which is connected to the computing and control device.

The computing and control device can in particular be designed to define the time interval and/or the additional time interval and possibly several additional time intervals, if corresponding selections are made, and/or to execute the temperature model. Furthermore, it can be designed to make a selection. The computing and control device can be designed to carry out the checking process. Alternatively or additionally, it can be designed to carry out the follow-up process, ie either to carry out the checking process and the follow-up process again or to output a signal using an output device or to take no further action.

The temperature value of the battery can be recorded with a temperature sensor. In a simple embodiment, only a single temperature value is used for comparison with a target temperature value determined by the temperature model. In more complex embodiments, multiple temperature values can be used. Multiple temperature values can then be compared to multiple corresponding set temperature values, respectively. Temperature values can, for example, be recorded on several different or all battery cells or battery blocks or modules or cell stacks or clusters in the battery using a temperature sensor and can be used for comparison. In particular, an average value of the temperatures of several or all battery cells or battery blocks or modules or cell stacks or clusters can be used as the temperature value. A comparison can be made with a corresponding target average value. Such an average value can be calculated using the calculation and Control device are determined. The average value can be determined using temperature values recorded using multiple sensors.

Alternatively or additionally, a difference in temperature values within the battery can be considered. It is possible that the absolute amount of the difference is considered. Such a difference can be determined in particular with the aid of the computing and control device. The difference can be determined using temperature values that are recorded using a number (in particular two) temperature sensors. The difference can then be compared with a corresponding target difference. The target difference can be determined by the temperature model

In particular, the difference can be a maximum difference in the temperatures within the battery, in particular in relation to temperature values of different battery cells or battery blocks or modules or cell stacks or clusters, which are determined by temperature sensors. The maximum difference can then be compared to a maximum target difference. Temperature values or differences in temperature values can be recorded or determined at various possible points in time and used for comparison with corresponding target temperature values determined using the temperature model. In particular, you can be recorded at the beginning of the verification process or at a point in time before and/or after the time interval has expired and/or after further time intervals have expired.

• - Batteriegröße,
• - das Batteriegewicht,
• - geometrische Angaben zur Batterie,
• - Angaben zum Ladezustand der Batterie, und/oder
• - weitere physikalische Eigenschaften der Batterie (zum Beispiel Messwerte eines Drucksensors oder eines Spannungssensors),

betreffen.Properties of the motor vehicle and/or the battery and/or the environment can be input variables or parameters or variables used in the temperature model or can be taken into account in it. In particular, it can be about values that

• - battery size,
• - the battery weight,
• - geometric information about the battery,
• - information on the state of charge of the battery, and/or
• - other physical properties of the battery (e.g. readings from a pressure sensor or a voltage sensor),

affect.

• - seit einer Beendigung eines Betriebs oder eines Ladevorgangs vergangene Zeit,
• - ein zeitliches Intervall oder ein weiteres zeitliches Intervall,
• - einen Wärmedurchgangskoeffizienten oder eine Wärmeleitfähigkeit der Batterie,
• - einen Wärmeübergangskoeffizienten zwischen der Batterie und dem sie umgebenden Medium (ggf. Luft),
• - Angaben zum Alter der Batterie,
• - Angaben zum Balancing-Verhalten der Batterie oder
• - einen Wert der Umgebungstemperatur

handeln.It can also be about, for example

• - time elapsed since termination of an operation or a charging process,
• - a time interval or a further time interval,
• - a heat transfer coefficient or thermal conductivity of the battery,
• - a heat transfer coefficient between the battery and the medium surrounding it (possibly air),
• - information on the age of the battery,
• - Information on the balancing behavior of the battery or
• - a value of the ambient temperature

Act.

The temperature model can include a thermal simulation, for example. Such a thermal simulation can be set up, for example, using an analytical or a numerical approach or an empirical approach. The temperature model can, for example, take into account Fourier's basic law of heat conduction or be based on this law. The temperature model can include a simulation of a temperature development according to an exponential approach. The temperature model can also include an FEM model, in particular an FEM model that simulates temperature developments, or build on or be based on it.

The determination of the result can include a subtraction, ie a difference formation, between the temperature value or temperature difference with the corresponding target temperature value or corresponding target temperature difference. So the result can be the result of such a subtraction. Alternatively or additionally, the result can be or include a qualitative indication.

With the help of the result of the comparison of a temperature value or the results of the comparison of several temperature values and, if applicable, one or more of the named temperature differences with the corresponding target values, the selection can be made with the aid of the assessment criterion. In a simple embodiment, all that is necessary is a temperature value for comparison with a setpoint temperature value, with the temperature value being recorded at a point in time after the time interval has elapsed.

The assessment criterion can in particular be formulated mathematically. It may include at least one threshold. If, for example, a temperature difference between the temperature and the target temperature is higher than a threshold value as a result, a selection can be made in such a way that the checking process and the follow-up be performed again or a signal is output. The assessment criterion can have several threshold values. In particular, threshold values can define intervals. Depending on the interval in which the result is, the verification process and the follow-up process are performed again, a signal is issued, or no further action is taken.

In the assessment criterion, values of various other sensors or other variables can serve as input variables or parameters or be taken into account, which can also be used to make the selection: For example, a value of a pressure sensor, in particular a pressure sensor on/in the battery; a value of a gas sensor that can detect outgassing of a battery cell, for example; a value of an optical sensor that can detect, for example, a change in shape or an opening of a battery cell or the battery; a value of a voltage sensor on the battery; and/or a value that describes a balancing behavior of the battery. For example, a voltage difference 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.

The selection can be made, for example, in the form of an electronically processable selection value. The selection value can have any configuration. In a simple form, a choice value is just one of a choice of three values corresponding to the different variants that are possible within the follow-up process.

In general, the checking process and the follow-up process can be carried out again, in particular if a future or impending thermal runaway cannot be ruled out. The checking process and the follow-up process can also be carried out again if a thermal runaway has already occurred but no or no fire development and/or explosion of the battery is to be expected. A further implausibility in the battery, for example an increased self-discharge rate or an increased need for balancing of the battery, can lead to the checking process and the subsequent process being carried out again. A further time interval is defined when a further checking process is carried out again. It can differ individually from the first time interval, in particular it can be shorter or longer. The condition of the battery in particular can be decisive for the length(s) of the further time interval or several time intervals: If there is a risk of thermal runaway or if it has already occurred (e.g. in a form that does not promise any immediate danger), a short interval can be used to get voted. A different temperature value can (and will in most cases in practice) be used as the target temperature value. A different selection may result, although the same evaluation criterion is used.

In particular, a signal is output when a thermal runaway is detected. In this context, activation or reactivation of control units, in particular the computing and control device, with which the method is carried out, can take place. The signal can be issued in particular when there is a risk (e.g. explosion, fire). In particular, it can be an optical or acoustic signal. For example, it may be dispensed inside the automobile and/or dispensed outside. For example, it can be an indication on a display and/or a signal from a horn and/or a hazard warning flasher function. Alternatively or additionally, the signal can be output to another device, in particular a smartphone or a computer, for example using a wireless data connection, for example a mobile phone connection or a wireless network connection. In this way, an external person or an external device can be informed about the signal, for example a manufacturer of the motor vehicle or a state authority. Alternatively or additionally, the outputting of the signal can be or include the outputting of corresponding electronic data with the aid of the computing and control device.

Before a thermal runaway occurs and/or a signal is output, at least one control unit of the motor vehicle can be activated or reactivated, in particular the computing and control device with which the method is carried out. The at least one control unit, in particular the computing and control device, with the aid of which the method is carried out, can be designed to trigger at least one other additional measure within the motor vehicle in such a situation. Such a different additional measure can be taken in particular if an imminent or imminent thermal runaway cannot be ruled out or is assumed, for example if there is no imminent danger (e.g. explosion, fire) but the battery is already in a critical condition, e.g Temperature or a temperature difference or a power loss that leaves or exceeds a specified range or a predetermined threshold value, and / or another implausibility of battery has/have occurred. The other additional measure can in particular be or include an activation of a cooling function, in particular a cooling function that relates to the battery.

It is also conceivable that a person is informed about further data or information relating to the method, for example temperature intervals or checking procedures, or such data or information is sent to an external computer, for example a server in a network. Information obtained in this way, for example optimized or updated setpoint temperature values, assessment criteria or an optimized or updated temperature model, can in turn be sent to the motor vehicle and in particular to the computing and control device for use.

It cannot be ruled out that information will be output, in particular automatically, if a further checking process and a further subsequent process are carried out in a subsequent process. This can in particular be, for example, warning information, for example a warning lamp lighting up, and/or status information which indicates information about the status of the battery and/or the vehicle.

No further action can be taken, especially if a thermal runaway can be ruled out.

The method presented can be carried out at least largely or completely using existing hardware, in particular hardware that relates to control and/or battery management and/or active balancing of the battery. Only or almost only a software adjustment is necessary. The implementation of the method is inexpensive and simple.

A thermal runaway of batteries in motor vehicles or an impending thermal runaway is detected particularly reliably, since the method can be used to detect when the motor vehicle is switched off, parked, stationary or not in use - possibly for a longer period of time for example several hours or several days. In particular, fires caused by unattended motor vehicles, for example in garages or multi-storey car parks, or fires that can spread to other objects/structures/houses can be avoided in this way.

In particular, since the motor vehicle can be in a sleep mode during the time intervals, the energy consumption for the monitoring can be very low. Typical time intervals can be on the order of 30, 45 or 60 minutes. However, longer or shorter time intervals are also possible. The software needed to carry out the method can easily be updated, for example using a wireless connection.

• - einer Betriebsart und/oder
• - einer Ladeart

der Batterie vor der Beendigung des Betriebs oder des Ladevorgangs und/oder in Abhängigkeit

• - eines Temperaturwerts der Batterie und/oder
• - eines Werts einer Temperaturdifferenz von zwei Orten in der Batterie und/oder
• - eines Werts der Umgebungstemperatur und/oder
• - eines Werts einer Verlustleistung der Batterie.

The time interval is determined in dependence

• - an operating mode and/or
• - a type of charging

of the battery prior to the termination of operation or charging and/or in dependence

• - a temperature value of the battery and/or
• - a value of a temperature difference of two locations in the battery and/or
• - a value of the ambient temperature and/or
• - a value of a power dissipation of the battery.

In particular, the values mentioned or at least one of the values mentioned can be recorded at the time when the operation or the charging process ends or before or after, for example at the time the time interval is defined.

The operating mode can in particular be a traction operation of the battery, in particular a power output when the motor vehicle is being driven. A distinction can be made in particular according to the stress on the battery caused by driving. If, for example, a journey was made at high speed and/or high acceleration shortly before the end of operation, the battery can have comparatively high temperatures and/or high temperature differences, in particular due to the high power output. The time interval can be adjusted accordingly. In particular, it can be comparatively short in such a case, for example half an hour. Subsequent further time intervals can also be comparatively short, in particular shorter than the (first) time interval and/or become increasingly shorter or longer.

If, on the other hand, the driving operation was characterized by low power output, the battery can have comparatively low temperatures and/or small temperature differences. In this case, the time interval can be adjusted. In particular, it can be comparatively long, for example one hour. Also subsequent white Further time intervals can be comparatively long, in particular longer than the (first) time interval and/or become increasingly longer or shorter. The same applies to a charging process: A charging process with high electrical power (e.g. direct voltage charging) can result in high temperatures or high temperature differences. The time interval can be comparatively short. Subsequent further time intervals can also be comparatively short, in particular shorter than the (first) time interval and/or become increasingly shorter or longer. When charging with low electrical power, the time interval can be comparatively long. Subsequent further time intervals can also be comparatively long, in particular longer than the (first) time interval and/or become increasingly longer or shorter.

Furthermore, high temperature values of the battery and/or high temperature differences in absolute terms from two locations in the battery can lead to the specification of a comparatively short interval. Subsequent further time intervals can also be comparatively short, in particular shorter than the (first) time interval and/or become increasingly shorter or longer. Low temperature values/absolute temperature differences can lead to the definition of a comparatively long interval. Subsequent further time intervals can also be comparatively long, in particular longer than the (first) time interval and/or become increasingly longer or shorter. It is possible that a value of a power loss of the battery is also taken into account when determining the time interval. A high power loss can in particular lead to the specification of a comparatively short interval. Subsequent further time intervals can also be comparatively short, in particular shorter than the (first) time interval and/or become increasingly shorter or longer.

A value of the ambient temperature (in particular a value of the ambient temperature at the current time and/or at the time when the operation or the charging process ended) can also be used. A high ambient temperature, which reduces cooling of the battery, can in particular result in a comparatively short time interval being specified. Subsequent further time intervals can also be comparatively short, in particular shorter than the (first) time interval and/or become increasingly shorter or longer. A low ambient temperature can, in particular, lead to the setting of a comparatively long time interval. Subsequent further time intervals can also be comparatively long, in particular longer than the (first) time interval and/or become increasingly longer or shorter.

The computing and control device can be designed to determine and define a time interval with the help of a model—in particular, this can be an empirical, numerical or analytical model. In particular, an interface or an exchange with the temperature model can be present or made. The temperature model itself can have a function for defining the time interval and can be used for this purpose. The computing and control device can be designed to use appropriate devices, for example appropriate sensors, to register which operating mode and/or which charging type was/was present before the end of the operation or the charging process.

The embodiment described offers a particularly simple way of defining the time interval. Furthermore, the operating mode and the type of charging as well as the values mentioned each have a high informative value, which in particular leads to a reliable determination of a meaningful time interval. Time intervals that are not too short, in particular, can reduce the energy consumption per unit of time on average.

• - eines Temperaturwerts der Batterie und/oder
• - eines Werts einer Temperaturdifferenz von zwei Orten in der Batterie und/oder
• - eines Werts der Umgebungstemperatur und/oder
• - eines Werts einer Verlustleistung der Batterie

zum Zeitpunkt der Festlegung des weiteren zeitlichen Intervalls.In one embodiment, the at least one further time interval is determined as a function

• - a temperature value of the battery and/or
• - a value of a temperature difference of two locations in the battery and/or
• - a value of the ambient temperature and/or
• - a value of a power dissipation of the battery

at the time the further time interval is determined.

• - eine Betriebsart und/oder
• - eine Ladeart

der Batterie vor der Beendigung des Betriebs oder des Ladevorgangs berücksichtigt wird/werden. Wenn von dem mindestens einen weiteren zeitlichen Intervall gesprochen wird, heißt dies im Falle von mehreren weiteren zeitlichen Intervallen, dass jedes weitere zeitliche Intervall individuell bestimmt werden kann. Die in Bezug auf das (erste) zeitliche Intervall genannten Vorteile gelten ansonsten entsprechend.The comments regarding the (first) time interval apply accordingly. In addition, it cannot be ruled out that values recorded earlier, for example at the time of the end of operation or the charging process, are taken into account when determining the further time interval. It is also not excluded that

• - an operating mode and/or
• - a type of loading

of the battery is/are taken into account before ending operation or charging. If from the at least one other temporal Interval is spoken, this means in the case of several further time intervals that each further time interval can be determined individually. The advantages mentioned in relation to the (first) time interval otherwise apply accordingly.

• - ein Wert einer Temperaturdifferenz von zwei Orten in der Batterie zu einem Zeitpunkt der Beendigung oder vor der Beendigung des Betriebs oder des Ladevorgangs,
• - ein Temperaturwert in der Batterie zu einem Zeitpunkt der Beendigung oder vor der Beendigung des Betriebs oder des Ladevorgangs.

In one embodiment, the input variables are used in the temperature model

• - a value of a temperature difference of two locations in the battery at a time of termination or before the termination of operation or charging,
• - a temperature value in the battery at a time of termination or before termination of operation or charging.

These values can be used in the temperature model in particular to determine the respective target values. A current value of the temperature difference from two locations in the battery and a current temperature value in the battery can then be compared with these target values. The results of the comparisons can then be used to make a selection with regard to the follow-up process.

In this context it should be mentioned that in general, not limited to the presented embodiment, it is not excluded that an assessment criterion allows several input values, for example values of the temperature difference and the temperature, to be taken into account. It is also not excluded that several assessment criteria are used. In particular, a single selection can still be made.

Based on the value of the temperature difference and the temperature value at a point in time at the end or before the end of the operation or the charging process, a time course/courses can be displayed, taking into account the respective current value/values. These time curves can in particular be compared with target curves. Forecasts and/or extrapolations can also be made and compared with one another and taken into account when making a selection.

The embodiment presented represents a simple embodiment that is based on a meaningful database. The sensory, hardware and computational effort is low. The energy consumption and the costs required for implementation are also low.

In one embodiment, during the time interval and/or during the at least one further time interval, a computing and control device in the motor vehicle that is used to carry out the method is switched off and/or is in a standby mode and/or is that Motor vehicle put into a sleep mode.

This avoids the battery being discharged during the time interval and/or during one or more further time intervals, or discharging of the battery is reduced. The energy consumption is low. In particular, more, almost all, or all of the arithmetic and/or control units and/or other consumers of the motor vehicle can be switched off or in a standby mode. Such a mode can also be referred to as a sleep mode. A sleep mode can be used in particular when the motor vehicle is parked or standing still.

In one embodiment, the computing and control device is reactivated and/or the motor vehicle is reactivated from the sleep mode using an electronic circuit that is designed for time measurement. The circuit can be connected to the computing and control device. In particular, it can be designed to measure a time interval. It can be designed to emit an activation signal after the time interval has elapsed. In particular, the circuit can have a timer. The circuit can have its own energy store, for example a rechargeable battery. Alternatively or additionally, the circuit can be connected to the battery of the motor vehicle for the purpose of supplying energy.

The presented embodiment reduces the energy consumption of the motor vehicle during the use of the presented method. Furthermore, the implementation is easy. The hardware effort is low. The costs are also low.

• - eine Batterie;
• - eine Rechen- und Steuereinrichtung, die ausgestaltet ist,

nach einer Beendigung eines Betriebs oder eines Ladevorgangs der Batterie einen Überprüfungsvorgang durchzuführen, bei dem ein zeitliches Intervall festgelegt wird und nach Ablauf des zeitlichen Intervalls ein Vergleich eines Temperaturwerts der Batterie mit einem Soll-Temperaturwert durchgeführt wird, wobei der Soll-Temperaturwert mithilfe eines Temperaturmodells, das eine Soll-Abkühlung der Batterie beschreibt, bestimmt wird, und mithilfe des Ergebnisses des Vergleichs eine Auswahl mithilfe eines vordefinierten Beurteilungskriteriums derart getroffen wird, dass bei einem Folgevorgang, zu dessen Durchführung die Rechen- und Steuereinrichtung ausgestaltet ist, entweder der Überprüfungsvorgang als weiterer Überprüfungsvorgang erneut durchgeführt wird, wobei bei dem weiteren Überprüfungsvorgang ein weiteres zeitliches Intervall festgelegt wird und nach Ablauf des weiteren zeitlichen Intervalls ein weiterer Vergleich eines weiteren Temperaturwerts der Batterie mit einem mithilfe des Temperaturmodells bestimmten weiteren Soll-Temperaturwert durchgeführt wird und mithilfe des Ergebnisses des weiteren Vergleichs eine weitere Auswahl mithilfe des Beurteilungskriteriums getroffen wird, wobei der Folgevorgang als weiterer Folgevorgang abhängig von der weiteren Auswahl erneut durchgeführt wird, oder ein Signal ausgegeben wird, oder keine weitere Maßnahme ergriffen wird;

• - eine Ausgabeeinrichtung, die ausgestaltet ist, das Signal auszugeben, wobei die Ausgabeeinrichtung mit der Rechen- und Steuereinrichtung verbunden ist;
• - mindestens einen Temperatursensor, der ausgestaltet ist, eine Temperatur der Batterie zu messen, wobei der Temperatursensor mit der Rechen- und Steuereinrichtung verbunden ist.

Furthermore, a motor vehicle is proposed, in particular with an electric or hybrid electric drive

• - a battery;
• - a computing and control device that is designed

after an operation or a charging process of the battery has ended, carry out a checking process in which a time interval is defined and after the time interval has elapsed a comparison of a temperature value of the battery with a target temperature value is performed, the target temperature value using a temperature model, this is a target cooling of the battery describes, is determined, and using the result of the comparison, a selection is made using a predefined assessment criterion in such a way that in a follow-up process, for which the computing and control device is designed to be carried out, either the checking process is carried out again as a further checking process, wherein in which further checking process, a further time interval is defined and after the further time interval has elapsed, a further comparison of a further temperature value of the battery with a further target temperature value determined using the temperature model is carried out and using the result of the further comparison, a further selection is made using the assessment criterion wherein the follow-up process is performed again as a further follow-up process depending on the further selection, or a signal is output, or no further action is taken;

• - an output device which is designed to output the signal, the output device being connected to the computing and control device;
• - At least one temperature sensor, which is designed to measure a temperature of the battery, wherein the temperature sensor is connected to the computing and control device.

• - einer Betriebsart und/oder
• - einer Ladeart

der Batterie vor der Beendigung des Betriebs oder des Ladevorgangs und/oder in Abhängigkeit

• - eines Temperaturwerts der Batterie und/oder
• - eines Werts einer Temperaturdifferenz von zwei Orten in der Batterie und/oder
• - eines Werts der Umgebungstemperatur und/oder
• - eines Werts einer Verlustleistung der Batterie.

The time interval is determined in dependence

• - an operating mode and/or
• - a type of charging

of the battery prior to the termination of operation or charging and/or in dependence

• - a temperature value of the battery and/or
• - a value of a temperature difference of two locations in the battery and/or
• - a value of the ambient temperature and/or
• - a value of a power dissipation of the battery.

The motor vehicle can be designed in particular to carry out the method presented. The above comments apply accordingly. The arithmetic and control device can in particular be designed as a control device and/or computer or include such a device. The output device can be designed in particular so that it can output an optical, haptic or acoustic signal to a person who is in the motor vehicle or outside, for example nearby. In particular, it can be a warning signal. The output device can also be designed so that it outputs a signal to another device via an interface. The signal can also be passed on to another device, for example a server or a smartphone, by means of a wireless connection, in particular a mobile radio or wireless network connection.

With regard to the further configurations, reference is made in full to the preceding descriptions relating to the method.

• 1 eine schematische Ansicht einer Ausgestaltung des erfindungsgemäßen Verfahrens,
• 2 eine schematische Ansicht einer Ausgestaltung des erfindungsgemäßen Kraftfahrzeugs.

The invention is explained in more detail below using an exemplary embodiment of the method according to the invention and an exemplary embodiment of the motor vehicle according to the invention. The figures show:

• 1 a schematic view of an embodiment of the method according to the invention,
• 2 a schematic view of an embodiment of the motor vehicle according to the invention.

The same reference symbols are used for the same, functionally identical or similar parts/assemblies/steps/values/information/facts or areas.

In 1 a schematic view of an embodiment of the method according to the invention is shown. In a first step S1, a charging process for a battery 3 of a motor vehicle 1 (see 2 ) completed. This will in 1 shown schematically by a symbolic connector on the battery 3, which is separated from a charging station shown schematically. Alternatively, another mode of operation of the battery 3 can also be terminated, in particular an operation in the form of power output when the motor vehicle 1 is driving. The battery 3 can in particular be a traction battery. In particular, it can be an electrochemical battery, for example a lithium-ion battery. The motor vehicle can in particular be a motor vehicle with an electric or hybrid electric drive.

In a second step S2, a computing and control device 2 (see 2 ) determines a time interval ZI. The time interval ZI can be three quarters of an hour, for example. Information LA on a type of charging of the battery 3 of the motor vehicle 1 is used for the determination. Before the completion of charging, the battery 3 was charged by, for example, DC charging under a high charging power.

Furthermore, a value of the ambient temperature TU, which is recorded using a corresponding sensor, for example, is used de. Furthermore, the value of a maximum temperature difference TDB in the battery 3 at the time of completion of charging is used. It is determined using sensors on the battery 3 and using the computing and control device 2 . The sensors can be, for example, sensors SE1, SE2, SE3 and SE4 (cf. third step S3). Furthermore, an average temperature TMB in the battery 3 at the time of completion of charging is used. It is again determined using sensors on the battery 3 and the computing and control device 2 . The sensors can be, for example, sensors SE1, SE2, SE3 and SE4.

The time interval ZI expires. this is in 1 represented schematically by a rounded rectangle symbol containing the reference mark "ZI" for the time interval ZI and arrows above and below it. The computing and control device 2 can be switched off or in a standby mode. Further control units of the motor vehicle 1 can also be switched off or in a standby mode. In particular, the motor vehicle 1 can be placed in a sleep mode. After the end of the time interval ZI, the computing and control device 2 can be activated again and, if necessary, further control units can be switched on again and the sleep mode can be ended if necessary. This can be done using an activation circuit 4 . This is schematic in 1 indicated, in which the reference number 4 are shown with an arrow. The activation circuit 4 can be designed in particular for time measurement.

In a third step S3, a value TDA of a maximum temperature difference and an average temperature TMA in the battery 3 are determined at a point in time after the time interval ZI has elapsed. This can be done in particular using the computing and control device 2. Temperature values T1, T2, T3, T4, which are recorded in the battery 3 at several locations (e.g. different battery cells or battery blocks or modules or cell stacks or clusters) using temperature sensors SE1, SE2 , SE3, SE4 can be measured. this is in 1 represented schematically by corresponding representations of the temperature sensors SE1, SE2, SE3, SE4 and arrows emanating from them.

In a fourth step S4, the value TDA of the maximum temperature difference (time after the time interval ZI has elapsed) is compared with a corresponding target value, and the mean temperature TMA (time after the time interval ZI has elapsed) is compared with a corresponding target value. This can be done in particular using the computing and control device 2.

The setpoint values mentioned are a setpoint value TDS of a maximum temperature difference in the battery 3 at the time after the time interval ZI has elapsed and a setpoint mean temperature value TMS in the battery 3 at the time after the time interval ZI has elapsed.

The specified target values are determined using a temperature model TMO. The temperature model TMO particularly takes into account the value of the maximum temperature difference TDB in the battery 3 (time when the charging process ended) and the average temperature TMB in the battery 3 (time when the charging process ended). Other variables and parameters can also be taken into account, for example a value for the ambient temperature or geometric or physical information about the battery 3.

The results of the comparisons, a first result E1 and a second result E2, can be determined, for example, by calculating the difference between the actual value and the target value. In a fifth step S5, a selection A is made on the basis of the first result E1 and the second result E2 using an assessment criterion BK, which in particular allows both results E1 and E2 to be assessed jointly. In particular, the assessment criterion BK can have intervals and threshold values. If the first or the second result lies in a respective corresponding interval, a corresponding selection is made. In particular, in the case of, for example, certain differences between actual and target values, either the checking process is carried out again as a further checking process and the follow-up process is carried out again as a further follow-up process, or, if the differences are large, for example, a signal, in particular a warning signal , spent. In particular, the computing and control device 2 can be used for this purpose. If the differences between the actual and target values are small, no further action can be taken as a follow-up process.

The steps from the second step S2 to the fifth step S5 are referred to as a verification process. A sixth step S6 and a seventh step in any variant (S7-1, S7-2, S7-3) are referred to as a follow-up process.

Selection A describes which measure is selected as the follow-up process. The follow-up process will start in 1 schematically symbolized by a sixth step S6. There are three variants of how the follow-up process can be implemented, which are represented as three different seventh steps S7-1, S7-2, S7-3. Either one will Signal output (seventh step [first variant] S7-1), in particular with an output device 5 ( 2 ), or no further action is taken (seventh step [second variant] S7-2) or the checking process is carried out again, i.e. another checking process, and the subsequent process is carried out again, i.e. another subsequent process (seventh step [third variant] S7-3).

In a further checking process, a further time interval is defined, a further comparison of a temperature value of the battery 3 with a target temperature value is carried out and a further selection is made. In the case of a further follow-up process, one of the three steps mentioned is again carried out (a signal is output; no further action is taken or the checking process is carried out again, i.e. another checking process and the follow-up process is carried out again, so another follow-up process).

As a consequence, a sequence of time intervals can result, after which a further comparison of a temperature value of the battery 3 with a setpoint temperature value is carried out and a further selection is made. The checking process and the follow-up process can, provided that further selections are made, be carried out again in succession, once or several times. The sequence can be terminated by making a selection that results in a follow-up action in which a signal is issued or no further action is taken.

In 2 a motor vehicle 1 according to the invention is shown very schematically. It has a battery 3, which can be laid in particular on the vehicle floor. The battery 3 can in particular be a traction battery of the motor vehicle 1 . in particular, it can be an electrochemical battery, in particular a lithium-ion battery. It 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 mobile radio or WLAN) or an indirect connection, for example via another device, which then forwards measured temperature values to the computing and control device 2, is also possible. Furthermore, the motor vehicle 1 has an output device 5 which can be part of the computing and control device 2 . The output device 5 can be designed to emit a humanly perceptible signal, in particular an optical or an acoustic signal. It can also be configured 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 . It is designed to reactivate the computing and control device 2 after time or other time intervals have elapsed.

In particular, the motor vehicle 1 can be designed to carry out the presented configurations of the method according to the invention. The comments on this apply accordingly.

Reference List

S1

first step: termination of a charging process of the battery

S2

second step: setting a time interval

ZI

time interval

S3

third step: Determination of a temperature average and a maximum temperature difference in the battery

S4

fourth step: comparison of the average temperature and the maximum temperature difference with the corresponding target values

S5

fifth step: selection using a predefined evaluation criterion

S6

sixth step: start of a follow-up process

S7-1

seventh step (first variant): output of a signal

S7-2

seventh step (second variant): take no further action

S7-3

seventh step (third variant): performing the verification process and the follow-up process again

L.A

Information on a charging type of the battery

do

Ambient temperature value

TDB

Value of a maximum temperature difference in the battery (time of termination of the charging process)

TMB

Mean temperature in the battery (point in time when charging was completed)

SE1

temperature sensor

SE2

temperature sensor

SE3

temperature sensor

SE4

temperature sensor

T1

temperature value

T2

temperature value

T3

temperature value

T4

temperature value

ZI

time interval

TDA

Value of a maximum temperature difference in the battery (point in time after the time interval has expired)

TMA

Mean temperature value in the battery (point in time after the time interval has expired)

TMO

temperature model

TDS

Target value of a maximum temperature difference in the battery (point in time after the time interval has expired)

TMS

Set average temperature in the battery (point in time after the time interval has expired)

E1

first result

E2

second result

A

selection

3

battery

1

motor vehicle

2

computing and control device

4

activation circuit

5

output device

BK

assessment criterion

Claims (10)

Method for detecting thermal runaway in a battery (3) of a motor vehicle (1), in particular a motor vehicle (1) with an electric or hybrid electric drive, a checking process being carried out after an operation or a charging process of the battery (3) has ended in which a time interval (ZI) is defined and after the time interval (ZI) has expired, a temperature value (T1, T2, T3, T4, TDA, TMA) of the battery (3) is compared with a target temperature value (TDS, TMS) is carried out, with the target temperature value (TDS, TMS) being determined using a temperature model (TMO), which describes a target cooling of the battery (3), and using the result (E1, E2) of the comparison, a selection (A ) is made using a predefined assessment criterion (BK) in such a way that in a subsequent process either - the checking process is carried out again as a further checking process, with a further time interval being specified in the further checking process and, after the further time interval has elapsed, a further comparison of a further temperature value of the battery (3) with a further target determined using the temperature model (TMO). - temperature value is carried out and using the result of the further comparison, a further selection is made using the assessment criterion (BK), the follow-up process being carried out again as a further follow-up process depending on the further selection; or - a signal is issued; or - no further action is taken, whereby the time interval (ZI) is determined in dependence - an operating mode and/or - A charging mode of the battery (3) before the termination of operation or charging and/or depending - a temperature value (TDB, TMB) of the battery (3) and/or - a value of a temperature difference (TDB) from two locations in the battery (3) and/or - a value of the ambient temperature (TU) and/or - a value of a power dissipation of the battery (3). procedure after claim 1 , characterized in that the at least one further time interval is defined as a function of - a temperature value of the battery (3) and/or - a value of a temperature difference between two locations in the battery (3) and/or - a value of the ambient temperature (TU ) and/or - a value of a power loss of the battery (3) at the time the further time interval is determined. Procedure according to one of Claims 1 or 2 , characterized in that in the temperature model (TMO) are used as input variables - a value of a temperature difference (TDB) from two locations in the battery (3) at a time of termination or before the termination of operation or charging, - a temperature value (TMB) in the battery (3) at a time of termination or before termination of operation or charging. Procedure according to one of Claims 1 until 3 , characterized in that during the time interval (ZI) and/or during the at least one further time interval, a computing and control device (2) of the motor vehicle (1), which is used to carry out the method, is switched off and/or is switched off is in a standby mode and/or the motor vehicle (1) is placed in a sleep mode. procedure after claim 4 , characterized in that the computing and control device (2) is reactivated and/or the motor vehicle (1) is reactivated from the sleep mode using an electronic circuit which is designed for time measurement. Motor vehicle (1), in particular with an electric or hybrid electric drive - a battery (3); - A computing and control device (2), which is designed to carry out a checking process after the end of an operation or a charging process of the battery (3), in which a time interval (ZI) is defined and after the time interval (ZI) has expired a temperature value (T1, T2, T3, T4, TDA, TMA) of the battery (3) is compared with a target temperature value (TDS, TMS), the target temperature value (TDS, TMS) being calculated using a temperature model (TMO ), which describes a target cooling of the battery (3), is determined, and using the result (E1, E2) of the comparison, a selection (A) is made using a predefined assessment criterion (BK) in such a way that in a follow-up process, too the execution of which the computing and control device (2) is configured, either the checking process is carried out again as a further checking process, with a further time interval in the further checking process is determined and after the further time interval has elapsed, a further comparison of a further temperature value of the battery (3) is carried out with a further setpoint temperature value determined using the temperature model (TMO) and using the result of the further comparison, a further selection is made using the assessment criterion (BK ) is taken, wherein the follow-up action is performed again as a further follow-up action depending on the further selection, or a signal is issued, or no further action is taken; - An output device (5) which is designed to output the signal, the output device (5) being connected to the computing and control device (2); - At least one temperature sensor which is designed to measure a temperature of the battery (3), the temperature sensor being connected to the computing and control device (2), the computing and control device (2) being designed to measure the time interval ( ZI) to be determined as a function - an operating mode and/or - A charging mode of the battery (3) before the termination of operation or charging and/or depending - a temperature value (TDB, TMB) of the battery (3) and/or - a value of a temperature difference (TDB) from two locations in the battery (3) and/or - a value of the ambient temperature (TU) and/or - a value of a power dissipation of the battery (3). Motor vehicle (1) after claim 6 , characterized in that the computing and control device (2) is designed to define the at least one further time interval as a function of - a temperature value of the battery (3) and/or - a value of a temperature difference between two locations in the battery (3) and/or - a value of the ambient temperature (TU) and/or - a value of a power loss of the battery (3) at the time the further time interval is determined. Motor vehicle (1) according to one of Claims 6 or 7 , characterized in that the computing and control device (2) is designed such that in the temperature model (TMO) are used as input variables - a value of a temperature difference (TDB) from two locations in the battery (3) at a time of termination or before cessation of operation or charging, - a temperature reading (TMB) in the battery (3) at a time of cessation or before cessation of operation or charging. Motor vehicle (1) according to one of Claims 6 until 8th , characterized in that the motor vehicle (1) is designed such that during the time interval (ZI) and / or during the at least one other time interval, the computing and control device (2) is switched off and / or in a standby Mode is and / or the motor vehicle (1) is placed in a rest mode. Motor vehicle (1) after claim 9 , characterized in that the motor vehicle (1) has an electronic circuit which is designed for time measurement and is also designed to trigger a reactivation of the computing and control device (2) and/or a reactivation of the motor vehicle (1) from the sleep mode.

Images