Method for determining an aged battery cell in a cell combination of parallel battery cells, computer program product and monitoring device

Abstract

The invention relates to a method for determining an aged battery cell (14) in a cell combination of parallel connected battery cells (14), comprising the following steps: applying an electrical signal (30) to the cell combination; at a first time instant, loading at least a first battery cell (14a) with a first ultrasonic signal (32a); at the first time instant, recording a first electrical response signal (34) of the electrical signal (30); at a second time instant, loading at least a second battery cell (14b) with a second ultrasonic signal (32b); at the second time instant, recording a second electrical response signal (34) of the electrical signal (30); comparing the first response signal (34) with the second response signal (34); determining a relative aging state of at least the first battery cell (14a) with respect to the second battery cell (14b) and thereby determining the aged battery cell (14). Further, the invention relates to a computer program product and a monitoring device (18).

Description

Technical Field

[0001] This invention relates to a method for identifying aged battery cells in a cell assembly of parallel battery cells in an electric energy storage device of at least a partially electrically driven motor vehicle, using a monitoring device, wherein, according to claim 1, the cell assembly has at least a first battery cell and a second battery cell connected in parallel therewith. Further, this invention relates to a corresponding computer program product and a monitoring device. Background Technology

[0002] It is known from existing technology that ultrasound can be used for the homogenization of liquids / slurries. Here, the application utilizes the so-called "cavitation effect," which is generated by the action of ultrasound waves in the liquid.

[0003] This effect can also be used to optimize lithium-ion battery cells. By applying ultrasound during the operation of the battery cell, the lithium concentration gradient in the electrolyte can be homogenized, thereby improving the performance of the battery cell, especially under high-rate and low-maintenance conditions. For example, during fast charging, a higher lithium-ion concentration forms near the cathode, while the electrolyte near the anode is deficient in lithium ions.

[0004] Specifically, due to increased operating time and calendar aging, the internal resistance of battery cells increases, and the energy / capacity of battery cells decreases. Because of the uneven current distribution within the energy storage device and variations in cells due to manufacturing processes, the aging of battery cells in an energy storage device will never be exactly the same. In a cell array, some battery cells will always age more severely than others. However, this is a self-reinforcing effect, as the more severely aged cells will disproportionately accelerate their aging further.

[0005] In current technology, it is impossible to measure parallel-connected battery cells individually. Therefore, in parallel combinations, it is impossible to locate defective or severely aged battery cells. Summary of the Invention

[0006] The purpose of this invention is to provide a method, a computer program product, and a monitoring device that can reliably identify defective battery cells within a cell assembly of parallel battery cells.

[0007] This objective is achieved by the method, computer program product, and monitoring device described in the independent claim. Advantageous embodiments are specified in the dependent claims.

[0008] One aspect of the present invention relates to a method for identifying aged battery cells in a cell assembly of parallel battery cells of an electric energy storage device in at least a partially electrically driven motor vehicle, using a monitoring device, wherein the cell assembly has at least a first battery cell and a second battery cell connected in parallel therewith. An electrical signal is applied to the cell assembly using a signal generation device of the monitoring device. At a first moment, a first ultrasonic signal is applied to at least the first battery cell using an ultrasonic device of the monitoring device. At the first moment, a first electrical response signal matching the first ultrasonic signal is acquired using a detection device of the monitoring device. At a second moment, a second ultrasonic signal is applied to at least the second battery cell using the ultrasonic device. At the second moment, a second electrical response signal matching the second ultrasonic signal is acquired using the detection device. The first response signal and the second response signal are compared with each other using an electronic computing device of the monitoring device. Then, the relative aging state of at least the first battery cell relative to the second battery cell is determined using the electronic computing device, thereby identifying the aged battery cell.

[0009] Specifically, this allows for a reliable determination of the relative aging state between two battery cells. Specifically, for example, based on the comparison results, it can be determined that the first battery cell has a higher aging state than the second battery cell, or vice versa.

[0010] Here, the first moment should specifically be considered as preceding the second moment. In other words, the first battery cell is checked first, followed by the second battery cell. For example, if the energy storage device is to have multiple battery cells, they are checked sequentially, especially the grid-type cells.

[0011] Therefore, in particular, this invention utilizes the ability to reduce the internal resistance of battery cells using ultrasound. This effect is now used to detect defective or severely aged battery cells in parallel configurations.

[0012] In particular, severely aged or defective battery cells exhibit varying degrees of resistance reduction when ultrasonic waves are activated, which can now be utilized by the method according to the invention. The detection of defective and / or severely aged battery cells is performed using the grid-like method described above. Here, an electrical signal is applied to the parallel assembly. Then, the parallel battery cells are grid-scanned by directly actuating the ultrasonic device. The corresponding response signals of the parallel assembly are then detected, and the response signals when the corresponding ultrasonic device is actuated are compared to detect severely aged battery cells.

[0013] In particular, this makes it possible to identify defective or severely aged battery cells in parallel battery cell assemblies. Therefore, it eliminates the need for reversible or irreversible disassembly of the cell assembly. This understanding allows for adjustments to the operation of slightly aged and severely aged battery cells and reduces current / voltage unevenness within the cell assembly.

[0014] According to an advantageous embodiment, a first ultrasonic signal is generated by a first ultrasonic element of the ultrasonic device, and a second ultrasonic signal is generated by a second ultrasonic element of the ultrasonic device. In other words, each battery cell is equipped with its own ultrasonic element. Therefore, by specifically actuating the corresponding ultrasonic element, an ultrasonic signal can be reliably transmitted to the battery cell, or in other words, a corresponding ultrasonic signal can be reliably applied to the battery cell. Thus, the aging state of the battery cell can be reliably determined.

[0015] Another advantageous implementation is designed to generate a current signal as an electrical signal. Specifically, the corresponding voltage can then be acquired as an electrical response signal. The aging state can then be reliably determined based on the current signal and the acquired voltage signal.

[0016] Furthermore, generating impedance spectrum signals as electrical signals has proven advantageous. Impedance spectroscopy is a technique used to study the electrical characteristics of a system over a frequency range. The impedance spectrum signal is the result of such measurements, consisting of real and imaginary parts, expressed in the form of complex impedances. In particular, the aging state can therefore be reliably determined from the impedance spectrum and the corresponding response signal.

[0017] In another advantageous embodiment, the ultrasonic signal is transmitted to the battery cell via an immersion medium. The immersion medium is, in particular, an oil, for example, found within the casing of an energy storage device. This makes it possible to reliably transmit the ultrasonic signal from the ultrasonic device to the battery cell via the immersion medium, thereby enabling reliable determination of the aging condition.

[0018] Another advantageous implementation is designed to determine the relative aging state of multiple parallel battery cells. Specifically, this allows for grid-like querying of multiple battery cells. This reliably determines the relative aging state between the battery cells. Corresponding measures can then be taken, enabling, for example, improved operation of the energy storage device.

[0019] Furthermore, it has proven advantageous to use a grid scanning method to determine multiple aging states. The grid scanning method specifically involves applying ultrasonic signals individually and sequentially to battery cells, particularly those connected in parallel, and acquiring the corresponding response signals. Thus, it is possible to determine which battery cells have aged relative to others using the grid scanning method.

[0020] In another advantageous embodiment, the ultrasonic device is designed to be arranged within the cover element of the battery cell assembly. This makes it possible to transmit ultrasonic signals to the battery cell in a simple manner. Furthermore, it makes it easier to wire the ultrasonic device from above.

[0021] The proposed method is, in particular, a computer-implemented method. Therefore, another aspect of the invention relates to a computer program product having program instructions that, when processed by an electronic computing device, cause the electronic computing device to perform the method described according to the foregoing aspects.

[0022] Therefore, the present invention also relates to a computer-readable storage medium having a computer program product according to the foregoing aspects.

[0023] Another aspect of the invention relates to a monitoring device for identifying aged battery cells in a cell assembly of parallel battery cells in an electric energy storage device of at least a partially electrically driven motor vehicle. The monitoring device includes at least one signal generation device, a detection device, an ultrasonic device, and an electronic computing device, wherein the monitoring device is designed to perform the method according to the foregoing aspect. In particular, the method is performed by means of the monitoring device.

[0024] Furthermore, the present invention also relates to an energy storage device having at least one monitoring device according to the foregoing aspects.

[0025] Similarly, the present invention also relates to a motor vehicle having an electric energy storage device according to the foregoing aspects. Here, the motor vehicle is specifically designed to be at least partially electrically driven or purely electrically driven.

[0026] Advantageous embodiments of this method are considered advantageous embodiments of computer program products, computer-readable storage media, monitoring devices, electrical energy storage devices, and motor vehicles. Therefore, the monitoring devices, electrical energy storage devices, and motor vehicles possess corresponding physical characteristics, enabling them to perform the corresponding method steps.

[0027] A computing unit / electronic computing device specifically refers to a data processing device containing processing circuitry. Therefore, a computing unit is particularly capable of processing data for performing computational operations. Where necessary, this also includes operations to perform indexed accesses on data structures (e.g., transformation tables, look-up tables).

[0028] A computing unit may specifically include one or more computers, one or more microcontrollers and / or one or more integrated circuits, such as one or more application-specific integrated circuits (ASICs), one or more field-programmable gate arrays (FPGAs), and / or one or more system-on-a-chip (SoCs). A computing unit may also include one or more processors, such as one or more microprocessors, one or more central processing units (CPUs), one or more graphics processing units (GPUs), and / or one or more signal processors, particularly one or more digital signal processors (DSPs). A computing unit may also include a combination of physical or virtual computers or a combination of the other units described above.

[0029] In different embodiments, the computing unit includes one or more hardware and / or software interfaces and / or one or more storage units.

[0030] Storage cells can be designed as volatile data memory, such as dynamic random access memory (DRAM) or static random access memory (SRAM), or as non-volatile data memory, such as read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory or flash-type EEPROM, ferroelectric random access memory (FRAM), magnetoresistive random access memory (MRAM), or phase-change random access memory (PCRAM).

[0031] Further advantages, features, and details of the invention are set forth in the following description of preferred embodiments and with reference to the accompanying drawings. Without departing from the scope of the invention, the features and combinations thereof mentioned in the specification, and the features and combinations thereof mentioned and / or shown individually in the accompanying drawings, may be used not only in their respective combinations, but also in other combinations or individually. Attached Figure Description

[0032] in: Figure 1 A schematic side view of a motor vehicle with an embodiment of an electric energy storage device and a monitoring device is shown. Figure 2 A schematic side view of one embodiment of the energy storage device is shown; and Figure 3 A schematic flowchart illustrating one embodiment of the method is shown; In the accompanying drawings, elements that are identical or have the same function have the same reference numerals. Detailed Implementation

[0033] Figure 1A schematic side view of one embodiment of a motor vehicle 10 is shown. The motor vehicle 10 has an electric energy storage device 12. The electric energy storage device 12 has at least two battery cells 14. The motor vehicle 10 is specifically designed to be at least partially electrically driven or purely electrically driven. For this purpose, the motor vehicle 10 has, for example, a drive unit 16 that can be driven by electrical energy from the electric energy storage device 12.

[0034] The energy storage device 12 has a monitoring device 18.

[0035] Figure 2 A schematic side view of one embodiment of the energy storage device 12 is shown. In this case, five battery cells 14 are specifically shown. In the current embodiment, a first battery cell 14a, a second battery cell 14b, a third battery cell 14c, a fourth battery cell 14d, and a fifth battery cell 14e are specifically shown.

[0036] For example, battery cells 14a to 14e can be located within the housing 20. In particular, battery cells 14a to 14e are essentially connected in parallel with each other.

[0037] Specifically, the monitoring device 18 is designed to identify aged battery cells 14a to 14d in a cell assembly of parallel battery cells 14a to 14e. For this purpose, the monitoring device 18 includes a signal generation device 22, a detection device 24, an ultrasonic device 26, and an electronic computing device 28.

[0038] Figure 3 A schematic flowchart illustrating one embodiment of the method is shown. Specifically, Figure 3 Multiple time steps S1 to S3 are shown in the figure.

[0039] Specifically, the design involves applying an electrical signal 30 to the cell assembly using a signal generation device 22. Using an ultrasonic device 26, at least one first ultrasonic signal 32a is applied to the first battery cell 14a at a first moment. Using a detection device 24, at the first moment, a first electrical response signal 34 matching the first ultrasonic signal 30 is acquired. Specifically, at a second moment, at least one second ultrasonic signal 32b is applied to the second battery cell 14b. Then, at the second moment, a second electrical response signal 34 matching the second ultrasonic signal 32b is acquired. Using an electronic computing device 28, the first response signal 34 and the second response signal 34 are compared. Then, using the electronic computing device 28, the relative aging state of at least three battery cells 14a to 14e is determined.

[0040] Specifically, the ultrasonic device 26 can be designed to have a first ultrasonic element 36a, a second ultrasonic element 36b, a third ultrasonic element 36c, a fourth ultrasonic element 36d, and a fifth ultrasonic element 36e. Here, the first ultrasonic element 36a is matched with the first battery cell 14a, the second ultrasonic element 36b with the second battery cell 14b, the third ultrasonic element 36c with the third battery cell 14c, the fourth ultrasonic element 36d with the fourth battery cell 14d, and the fifth ultrasonic element 36e with the fifth battery cell 14e. For example, the third ultrasonic element 36c can generate a third ultrasonic signal 32c, the fourth ultrasonic element 36d can generate a fourth ultrasonic signal 32d, and the fifth ultrasonic element 36e can generate a fifth ultrasonic signal 32e.

[0041] Specifically, it is therefore designed to generate a first ultrasonic signal 32a by means of a first ultrasonic element 36a and a second ultrasonic signal 32b by means of a second ultrasonic element 36b.

[0042] Alternatively, it can be designed to generate a current signal as electrical signal 30. Or, an impedance spectrum signal can be generated as electrical signal 30.

[0043] Furthermore, the ultrasonic signals 32a to 32e can be designed to be transmitted to the battery cells 14a to 14e via the immersion medium 38.

[0044] Furthermore, the device can be designed to determine the relative aging states of multiple parallel battery cells 14a to 14e. Further, it can be designed to determine multiple aging states using a grid scanning method. Here, the ultrasonic device 26 can be specifically arranged in the cover element 40 of the cell assembly.

[0045] As mentioned above, Figure 3 Three distinct steps, S1 to S3, are shown in detail. For example, in the first step S1, a first ultrasonic signal 32a is applied to the first battery cell 14a. In the second step S2, a second ultrasonic signal 32b is applied to the second battery cell 14b. In the third step S3, a third ultrasonic signal 32c is applied to the third battery cell 14c. This process continues until all battery cells 14a to 14e have been checked accordingly.

[0046] In summary, these figures illustrate the integration of ultrasonic elements 36a to 36e within the battery module. Severely aged or defective battery cells 14a to 14e exhibit varying degrees of resistance reduction when the ultrasonic waves are activated. This makes it possible to detect defective and / or severely aged battery cells 14a to 14e using a grid scanning method. Detection is achieved by acquiring the response signal 34 through the application of an electrical signal 30, a grid scan of the parallel-connected battery cells 14a to 14e, and direct actuation of individual ultrasonic elements 36a to 36e. This then makes it possible, for example, to compare voltage changes or impedance signals when the corresponding ultrasonic elements 36a to 36e are actuated, thereby detecting aged battery cells 14a to 14e.

[0047] List of reference numerals

Claims

1. A method for identifying aged battery cells (14) in a cell assembly of parallel battery cells (14) of an electric energy storage device (12) of at least a partially electrically driven motor vehicle (10) using a monitoring device (18), wherein, The cell assembly has at least a first battery cell (14a) and a second battery cell (14b) connected in parallel therewith, and includes the following steps: - Using the signal generation device (22) of the monitoring device (18), an electrical signal (30) is applied to the cell assembly; - Using the ultrasonic device (26) of the monitoring device (18), at least the first ultrasonic signal (32a) is applied to the first battery cell (14a) at the first moment. - Using the detection device (24) of the monitoring equipment (18), at the first moment, a first electrical response signal (34) of the electrical signal (30) that matches the first ultrasonic signal (32a) is acquired. - Using the ultrasonic device (26), at the second moment, at least the second battery cell (14b) is loaded with a second ultrasonic signal (32b). - Using the detection device (24), at the second moment, a second electrical response signal (34) of the electrical signal (30) that matches the second ultrasonic signal (32b) is acquired. - Using the electronic computing device (28) of the monitoring device (18), the first response signal (34) is compared with the second response signal (34); and - The electronic computing device (28) is used to determine the relative aging state of at least the first battery cell (14a) relative to the second battery cell (14b), and thereby determine the aged battery cell (14). The ultrasonic device (26) is arranged in the cover element (40) of the battery cell assembly.

2. The method according to claim 1, Its features are, The first ultrasonic signal (32a) is generated by means of the first ultrasonic element (36a) of the ultrasonic device (26), and the second ultrasonic signal (32b) is generated by means of the second ultrasonic element (36b) of the ultrasonic device (26).

3. The method according to claim 1 or 2, Its features are, A current signal is generated as the electrical signal (30).

4. The method according to claim 1 or 2, Its features are, An impedance spectrum signal is generated as the electrical signal (30).

5. The method according to any one of the preceding claims, Its features are, Ultrasonic signals (32a – 32e) are transmitted to the battery cell (14) via an immersion medium (38).

6. The method according to any one of the preceding claims, Its features are, Determine the relative aging state of multiple parallel battery cells (14).

7. The method according to claim 6, Its features are, Multiple aging states are determined using a grid scanning method.

8. A computer program product having program instructions that, when processed by the electronic computing device (28), cause the electronic computing device (28) to perform the method according to any one of claims 1 to 7.

9. A monitoring device (18) for identifying aged battery cells (14) in a cell assembly of parallel battery cells (14) of an electric energy storage device (12) of at least a partially electrically driven motor vehicle (10), the monitoring device comprising at least one signal generating device (22), a detection device (24), an ultrasonic device (26), and an electronic computing device (28), wherein, The monitoring device (18) is designed to perform the method according to any one of claims 1 to 7.

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