Method, computer program product and electronic computing device for determining thermal runaway of an electrical energy storage unit of an at least partially electrically driven motor vehicle - Patents.com

Abstract

The present invention relates to a method for determining thermal runaway of an electric energy store (12) of a driven motor vehicle, the method comprising: - a continuous monitoring of the electrical energy store (12) by means of at least one diagnostic means (14) of the electrical energy store (12) on the basis of a diagnostic signal (16), - if an anomaly (44) is detected in the diagnostic signal (16), determining the frequency (18) of the anomaly (44); - if an anomaly (44) is detected in the diagnostic signal (16), determining the magnitude of the anomaly (44); - continuously monitoring the communication line (24) by means of a limited anomaly counter (26); - if an anomaly (44) is detected in the communication line (24), performing a comparison between the limited anomaly counter (26) and the non-limited anomaly counter (28) and generating a difference signal (30) in response to the comparison; - determining thermal runaway as a function of the determined frequency (18), the determined momentum (22) and the difference signal (30). The invention further relates to a computer program product as well as an electronic computing device (10).

Description

[Technical field]

[0001] The invention relates to a method for determining a thermal runaway of an electrical energy store of an at least partly electrically driven motor vehicle by means of an electronic computing device of the motor vehicle according to the preamble of claim 1. Furthermore, the invention relates to a computer program product as well as to an electronic computing device. [Background technology]

[0002] For example, it is already known that in so-called electric vehicle batteries, as electric energy stores in motor vehicles, a warning must be given to the vehicle occupants, for example 5 minutes before a fire occurs, in the event of a possible thermal runaway, also called thermal runaway. Currently, a combination of voltage and insulation measurements is used in vehicles. If both an undervoltage and an insulation failure are detected, an alarm is triggered. However, the measurement of an insulation failure is relatively prone to errors. It is also known to incorporate dedicated additional sensors, such as pressure sensors. However, this increases the costs. Furthermore, the cell temperature itself can be used. However, since not all battery cells have a sensor and, depending on the mounting position, they may even be well shielded from hot gases, a considerable time offset may also occur with the temperature sensor. Such a measurement of the cell voltage alone is unreliable, since frequent false alarms may occur. For example, if the measurement line is broken, this may result in a false alarm, since no further signal is provided for plausibility check and an undervoltage is assumed to occur. Patent document 1 relates to an apparatus for identifying thermal runaway, a battery system, and a method for identifying thermal runaway in a battery system, wherein the apparatus for identifying thermal runaway includes a first measurement module for measuring temperature values ​​of a plurality of cells via at least one temperature sensor, a second measurement module for measuring an output voltage value of the battery system, and a control unit for determining the validity of identifying thermal runaway based on the temperature value by monitoring data received from the first measurement module, and for identifying thermal runaway in the battery system by selectively monitoring the temperature value or the output voltage value according to the result of the determination of the validity of identifying thermal runaway based on the temperature value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] EP3843195A1 Summary of the Invention [Problem to be solved by the invention]

[0004] It is an object of the present invention to provide a method, a computer program product and an electronic computing device, with which thermal runaway of an electrical energy store can be better detected. [Means for solving the problem]

[0005] This problem is solved by a method, a computer program product and an electronic computing device according to the independent claims. Advantageous embodiments are set forth in the dependent claims.

[0006] An aspect of the invention relates to a method for determining thermal runaway of an electric energy store of an at least partially electrically driven motor vehicle using an electronic computing device of the motor vehicle. The method comprises: a continuous monitoring of the electric energy store using at least one diagnostic means for determining a current state of the electric energy store based on a diagnostic signal. If an anomaly is detected in the diagnostic signal, a frequency of the anomaly in the diagnostic signal over a predetermined period of time is determined. Furthermore, if an anomaly is detected in the diagnostic signal, a momentum of the anomaly in the diagnostic signal over a predetermined period of time is determined. A communication line of the electric energy store is continuously monitored using a limited anomaly counter. If an anomaly is detected in the communication line, a comparison is made between the limited anomaly counter and a non-limited anomaly counter, and a difference signal is generated depending on the comparison. Depending on the determined frequency, the determined momentum and the difference signal, a determination of thermal runaway is performed.

[0007] This allows for improved identification of thermal runaway in the electrical energy store.

[0008] Thus, in particular, thermal runaway of a battery cell or an electric energy store, in particular an energy store in the form of a lithium-ion battery, can be detected robustly without the need for additional sensor systems. Since the cell monitoring electronics is in any case a component of the electric energy store, in particular an electric vehicle battery of a motor vehicle, the corresponding diagnostics are implemented to achieve so-called ASIL safety, so that no component costs are incurred and the software expansion is likewise small. Thus, by using existing systems or methods, thermal runaway can already be identified at reduced cost.

[0009] Thus, in particular, in order to be able to determine thermal runaway, cell voltage measurements are used, diagnostics are performed for the cell voltage measurements, signals derived from the diagnostics are calculated, thresholds are formed and the diagnostics are combined via corresponding AND operations.

[0010] Thus, in particular, the cell monitoring electronics has the task of measuring the cell voltage and the cell temperature. These values ​​are in any case checked by diagnostics for correct functioning, since they are used to achieve the safety goals according to the ASIL classification. These diagnostics are triggered if such an error / anomaly is present. Many of these errors occur during thermal runaway, also referred to as thermal runaway, and partly occur simultaneously. The challenge here is to separate thermal runaway from the actually existing error cases. To make matters worse, many hardware errors trigger multiple diagnostics, especially when no thermal runaway occurs. Here, in order to be able to achieve a better discrimination, the momentum of the error or anomaly is taken into account on the one hand, and the number of simultaneously occurring errors or anomalies is taken into account on the other hand.

[0011] Furthermore, in the case of a thermal runaway, accumulated communication errors also occur during transmission via a so-called daisy chain, which here corresponds to a communication line and can be formed, for example, as a CAN bus. In an implementation using so-called ASICs of analog functional components, these errors are counted using a so-called packet error counter (PEC). This PEC corresponds to an unqualified anomaly counter. However, even in normal conditions, for example when switching a protector, several packets can be corrupted, so that a check is also carried out here. For this purpose, the PEC is limited in its momentum using a so-called rate limiter, in other words a bounded anomaly counter, and then a difference with the actual PEC, which corresponds to the unqualified anomaly counter, is determined. If this difference signal exceeds a threshold value, this indicates a thermal runaway.

[0012] Therefore, from the combination of the momentum of the anomalies, the number of anomalies occurring simultaneously, and the difference signal, thermal runaway is inferred without any false detection.

[0013] According to an advantageous embodiment, the cell voltage line is monitored for interruption by means of a diagnostic means, in particular a diagnostic means already installed in the motor vehicle for monitoring the cell voltage measurement line, with which it is possible to check whether an anomaly exists and to monitor its momentum and frequency. This method is in particular the so-called open wire method.

[0014] Furthermore, it has proven to be advantageous if the switching state of a balancing semiconductor element is monitored using this diagnostic means. The balancing semiconductor element is in particular a so-called balancing FET element. In particular, here, it is possible to check, for example, whether this semiconductor element is not switched on or is in a permanently switched on state. This diagnostic means is likewise a diagnostic means that is already installed in the motor vehicle for monitoring the electric energy store.

[0015] In another advantageous embodiment, the diagnostic means is used to monitor short circuits between adjacent pins on the board of the electronic computing device. Likewise, the diagnostic means is a method already installed in automobiles for monitoring electric energy stores or electronic computing devices. In particular, it is a monitoring of whether a short circuit occurs between adjacent general purpose input / outputs (GPIOs), i.e. a pin on an ASIC to which, for example, a temperature sensor is connected is monitored.

[0016] Furthermore, the diagnostic means can be used to monitor deviations of the second reference voltage source, which is likewise a method already built into automobiles for monitoring electrical components, in particular battery cells, making it possible to determine thermal runaway in a simple manner.

[0017] Furthermore, it has been found to be advantageous if, using this diagnostic means, the total voltage is monitored via the board of the electronic computing device, in particular via the ASIC, and in particular whether this total voltage is not equal to the sum of the individual voltages. This method is also already built into the vehicle or the electrical energy store, so that thermal runaway can be estimated in a reliable and simple manner.

[0018] In another advantageous embodiment, a difference signal is generated only when a predefined threshold is exceeded between the limited and non-limited anomaly counters. For example, the limited anomaly counter can be rate-limited to 4 errors per second. If the threshold exceeds, for example, 20, this can be considered as an indication that an error / anomaly exists.

[0019] According to an advantageous embodiment, when a potential thermal runaway is determined, a warning message is outputted at an output device of the vehicle for a vehicle occupant. In particular, the warning message is outputted at least 5 minutes before the thermal runaway. The output device may be a haptic output device, an optical output device, or an acoustic output device. In particular, different warning messages, such as an acoustic warning signal, an optical warning signal, and a haptic warning signal, may be outputted simultaneously.

[0020] The presented methods are computer-implemented methods. Therefore, another aspect of the invention relates to a computer program product, the program code means being configured to cause an electronic computing device to perform a method according to the aforementioned aspect when the program code means is processed by the electronic computing device. In particular, the method is implemented using an electronic computing device. The computer program product may be referred to as a computer program.

[0021] Therefore, another aspect of the present invention also relates to a computer-readable storage medium including a computer program product.

[0022] Furthermore, the invention also relates to an electronic computing device for determining a thermal runaway of an electric energy store of an at least partially electrically driven motor vehicle, the electronic computing device being adapted to carry out the method according to the above-mentioned aspect, in particular the said method being carried out by means of said electronic computing device.

[0023] The electronic computing device comprises, for example, a processor, circuits, in particular integrated circuits, as well as other electronic components in order to be able to carry out the corresponding method steps.

[0024] The invention likewise relates to a motor vehicle with at least partly electric drive or a fully electric drive.

[0025] Advantageous embodiments of the method are to be regarded as advantageous embodiments of a computer program product, an electronic computing device as well as a vehicle, which are in particular characterized in that they are able to carry out the corresponding method steps.

[0026] Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. The features and combinations of features mentioned in the above description and below in the description of several figures and / or shown in a single figure can be used not only in the respective combinations described, but also in other combinations or alone, without departing from the scope of the invention. [Brief description of the drawings]

[0027] [Figure 1] Here, in the only figure, a schematic block diagram according to one embodiment of the method is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] In the drawings, identical or functionally identical elements are provided with the same reference numbers.

[0029] The figure shows a schematic block diagram of an embodiment of an electronic computing device 10 for determining a thermal runaway of an electric energy store 12 of an at least partially electrically driven motor vehicle. In this example, in particular, an operating sequence is shown. In particular, a continuous monitoring of the electric energy store 12 is performed by means of at least one diagnostic means 14 for determining the current state of the electric energy store 12 on the basis of a diagnostic signal 16. If an anomaly 44 is detected in the diagnostic signal 16, a frequency 18 of the anomaly 44 in the diagnostic signal 16 over a predefined time period 20 is determined. Furthermore, if an anomaly 44 is detected in the diagnostic signal 16, a momentum 22 of the anomaly 44 in the diagnostic signal 16 over a predefined time period 20 is determined. Furthermore, a continuous monitoring of the communication line 24 of the electric energy store 12 is performed by means of a limited anomaly counter 26. If an anomaly 44 in the communication line 24 is detected, a comparison is made between the limited anomaly counter 26 and a non-limited anomaly counter 28, and a difference signal 30 is generated depending on the comparison. Again, a thermal runaway determination is made as a function of the determined frequency 18, the determined momentum 22 and the difference signal 30.

[0030] In particular, a threshold comparison can be performed for this purpose. For example, a first threshold 32 greater than 100 can be provided as a measure of the frequency 18. In other words, a warning signal 34 for thermal runaway can be issued only if more than 100 anomalies 44 have been identified. Furthermore, a second threshold 36 can be provided, which here represents a momentum. For example, the momentum can relate to the absolute value of the derivative of the set number of bits and can include a second threshold 36 greater than or equal to 10. A third threshold 38 can be provided, which here represents a measure of significantly more frequently occurring communication errors and can be greater than 20, for example. Only when the comparisons of all three thresholds are classified positively, i.e. when the thresholds 32, 36 are exceeded, are they introduced into an AND operation 40. If all three thresholds 32, 36, 38 are exceeded, a warning message 34 is generated. The warning message 34 can be output, for example, at an output device 42 of the motor vehicle. For example, the output device 42 may be formed as a display device, a speaker device, or a haptic device.

[0031] The period 20 may be, for example, 20 seconds, or it may be another time span, for example, 40 seconds.

[0032] As already mentioned, it is shown here to provide an AND operation 40. For example, instead of performing the thresholding before the AND operation 40, alternatives are conceivable, such as performing a weighted addition and only performing the thresholding afterwards.

[0033] Thus, in particular, the figure shows that the cell monitoring electronics has the task of measuring the cell voltage and the cell temperature. These values ​​are used to achieve the safety objectives according to the corresponding ASIL classification, so that correct functioning is monitored by means of the diagnostic means 14. Such diagnostics include, for example, the interruption of the cell voltage measurement line, the so-called open wire diagnostics. Furthermore, the diagnostic means 14 can also be used to monitor, for example, the balancing semiconductor switching elements. For example, it can be checked whether these semiconductor elements are not switched on or are permanently switched on. This is also called a balancing FET stack. Furthermore, short circuits between adjacent boards, so-called general purpose input / outputs (GPIOs), can also be checked. Here, in particular, it is checked whether a short circuit occurs at the corresponding pins in the ASIC, to which, for example, a temperature sensor is connected. Furthermore, the deviation of the second reference voltage source can also be used as a monitor. Furthermore, the total voltage can also be checked via the ASIC, for example whether it is not equal to the sum of the individual voltages.

[0034] The diagnostic means 14 mentioned above are triggered if such an error / anomaly 44 exists. During a thermal runaway, many of these errors occur and partly occur simultaneously. The challenge here is to separate the thermal runaway from the actually existing error cases. To make matters worse, many hardware errors trigger multiple diagnostic means 14 even if they do not correspond to a thermal runaway. Here, both the momentum 22 and the frequency 18 of the anomaly 44 are taken into account in order to be able to achieve a better discrimination.

[0035] Furthermore, during thermal runaway, accumulated communication errors also occur during transmission via the communication line 24, in particular the so-called daisy chain. In an implementation using an analog device ASIC, these errors are counted using a so-called non-limited anomaly counter 28 (Packet Error Counter (PEC)). However, since even under normal conditions several packets can be corrupted, for example when switching a contactor, a discrimination is also performed here. For this purpose, the PEC is momentum-limited using a limited anomaly counter 26, the so-called Rate-Limiter, and the difference with the actual PEC is then determined. If this difference signal 30 exceeds a threshold, in particular the third threshold here, this indicates a thermal runaway.

[0036] The limited anomaly counter 26 may be rate limited, for example, to four errors or anomalies 44 per second.

[0037] When the frequency 18, momentum 22, and difference signal 30 exceed the corresponding thresholds 32, 36, 38, based on an AND operation 40, a thermal runaway is recognized and a warning signal 34 is generated. [Explanation of symbols]

[0038] 10 Electronic computing device 12 Electrical energy storage unit 14 Diagnostic Procedures 16 Diagnostic Signals 18 Frequency 20 period 22 Momentum 24 Communication lines 26 Limited Abnormality Counter 28 Unrestricted Anomaly Counter 30 Differential Signal 32 First Threshold 34 Warning Messages 36 Second Threshold 38 The third threshold 40 AND Operation 42 Output Device 44 Abnormality

Claims

1. 1. A method for determining thermal runaway in an electrical energy storage unit (12) of an at least partially electrically powered motor vehicle using an electronic computing device (10) of the motor vehicle, comprising: - continuously monitoring said electrical energy store (12) by means of at least one diagnostic means (14) for determining the current state of said electrical energy store (12) on the basis of a diagnostic signal (16); - if an anomaly (44) is detected in the diagnostic signal (16), determining the frequency (18) of the anomaly (44) in the diagnostic signal (16) over a predetermined period (20); - if an anomaly (44) is detected in the diagnostic signal (16), determining the behavior (22) of the anomaly (44) in the diagnostic signal (16) over a predetermined period (20); - continuously monitoring the communication line (24) of said electrical energy store (12) by means of a limited anomaly counter (26) which counts communication errors restricted to normal conditions; - if an anomaly (44) is detected in the communication line (24), comparing the limited anomaly counter (26) with an unlimited anomaly counter (28) that counts communication errors without limiting them to the normal state, and generating a difference signal (30) in response to said comparison; - determining said thermal runaway (44) in response to said determined frequency (18), said determined movement (22) and said difference signal (30); A method having the following.

2. 2. The method according to claim 1, wherein the diagnostic means (14) is used to monitor for interruptions in the cell voltage measurement lines.

3. 3. The method according to claim 1, wherein the switching state of the balancing semiconductor elements is monitored by means of the diagnostic means (14).

4. 3. The method according to claim 1, wherein the diagnostic means (14) is used to monitor short circuits between adjacent pins on the board of the electronic computing device (10).

5. 3. The method according to claim 1, wherein the diagnostic means (14) is used to monitor deviations of the second reference voltage source.

6. 3. The method according to claim 1, wherein the diagnostic means (14) monitors the total voltage via the board of the electronic computing device (10).

7. 3. The method according to claim 1, wherein the difference signal (30) is generated only when a predetermined threshold is exceeded between the limited anomaly counter (26) and the non-limited anomaly counter (38).

8. 3. The method of claim 1 or 2, wherein a potential thermal runaway is determined and a warning message is output at an output device of the vehicle for an occupant of the vehicle.

9. 1. A computer program product comprising program code means, 3. The computer program product, wherein said program code means, when processed by an electronic computing device (10), causes said electronic computing device (10) to perform the method of claim 1 or 2.

10. An electronic computing device (10) for determining thermal runaway of an electrical energy storage unit (12) of an at least partially electrically powered motor vehicle, comprising: The electronic computing device (10) is configured to implement the method according to claim 1 or 2.

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