System for diagnosing a current collector and associated computer-readable storage medium

Abstract

System for diagnosing a battery cell (204) of a vehicle (100), comprising: a processor (302) and a working memory (304) or data storage (308) comprising an algorithm or computer instructions which, when executed by the processor (302), perform an operation comprising: Determine that a current flows through a current collector (206, 214) of the accumulator cell (204), Generating a mechanical excitation of the current collector (206, 214), Determining the amplitude of a voltage across the accumulator cell (204) based on mechanical excitation, and Determining the presence of a crack or separation of a foil of the current collector (206, 214) on the basis of the amplitude of the voltage across the accumulator cell (204).

Description

INTRODUCTION

[0001] The present invention relates to the diagnosis of accumulator cells and in particular to the diagnosis of damage or cracks in current collector foils of accumulator cells.

[0002] For background information, reference is made at this point to the publications DE 10 2014 222 694 A1, DE 10 2018 121 027 A1, DE 10 2014 225 361 A1, DE 10 2014 204 956 A1 and DD 2 60 772 A1, from which it is known that it is possible to infer the condition of current collectors, current collectors, current arresters, discharge elements, connecting elements, connecting bodies or discharge tabs from mechanical vibrations.

[0003] A lithium-ion cell generally comprises current collector foils that facilitate the flow of electrons between the cell's cathode and anode. However, these current collector foils can become damaged or torn, which can impair the cell's performance. Techniques for diagnosing current collector foils generally involve opening the cells and examining the foils, rendering the cells unusable for subsequent operations or applications. SUMMARY

[0004] A method for diagnosing a vehicle battery cell is described. The method includes determining that a current is flowing through a current collector of the battery cell, generating a mechanical excitation for the current collector, determining the amplitude of a voltage across the battery cell based on the mechanical excitation, and determining the presence of a crack or separation of a film in the current collector based on the amplitude of the voltage across the battery cell.

[0005] In addition to one or more of the features described herein, the method also includes determining the time at which the tear or separation of the foil of the current collector occurred.

[0006] In addition to one or more of the features described herein, mechanical excitation is generated via a mechanical excitation unit arranged or positioned on an outer surface of the accumulator cell, or a film consolidation unit coupled to the accumulator cell.

[0007] In addition to one or more of the features described herein, the outer surface includes one of the following features: an anode tab of the accumulator cell, a cathode tab of the accumulator cell, or a surface that is in contact with a combination of an anode of the accumulator cell, a current collector on the anode, a foil expansion area of ​​the current collector on the anode, a cathode of the accumulator cell, a current collector on the cathode, a foil expansion area of ​​the current collector on the cathode, or a separator of the accumulator cell.

[0008] In addition to one or more of the features described herein, the mechanical excitation causes a displacement of the foil of the current collector, the displacement of the foil causing the crack or separation to close and open.

[0009] In addition to one or more of the features described herein, the voltage across the accumulator cell is passed through a high-pass filter (218) or a band-pass filter before being measured by a voltage measuring unit.

[0010] In addition to one or more of the features described herein, the amplitude is determined within a frequency band with a lower limit of greater than or equal to 1 Hertz.

[0011] According to the invention, a system for diagnosing a vehicle battery cell is presented, characterized by the features of claim 1. The system comprises a processor and a working memory or data storage device comprising an algorithm or computer instructions which, when executed by the processor, performs a process that includes detecting that a current is flowing through a current collector of the battery cell, generating a mechanical excitation for the current collector, determining the amplitude of a voltage across the battery cell based on the mechanical excitation, and detecting the presence of a crack or separation of a film of the current collector based on the amplitude of the voltage across the battery cell.

[0012] In addition to one or more of the features described herein, the process also includes determining the time at which the tear or separation of the foil of the current collector occurred.

[0013] In addition to one or more of the features described herein, mechanical excitation is generated via a mechanical excitation unit arranged or positioned on an outer surface of the accumulator cell, or a film consolidation unit coupled to the accumulator cell.

[0014] In addition to one or more of the features described herein, the outer surface includes one of the following features: an anode tab of the accumulator cell, a cathode tab of the accumulator cell, or a surface that is in contact with a combination of an anode of the accumulator cell, a current collector on the anode, a foil expansion area of ​​the current collector on the anode, a cathode of the accumulator cell, a current collector on the cathode, a foil expansion area of ​​the current collector on the cathode, or a separator of the accumulator cell.

[0015] In addition to one or more of the features described herein, the mechanical excitation causes a displacement of the foil of the current collector, the displacement of the foil causing the crack or separation to close and open.

[0016] In addition to one or more of the features described herein, the amplitude is determined within a frequency band with a lower limit of greater than or equal to 1 Hertz.

[0017] In addition to one or more of the features described herein, the voltage across the accumulator cell is passed through a high-pass filter or a band-pass filter before being measured by a voltage measuring unit.

[0018] Furthermore, according to the invention, a computer-readable storage medium is presented, comprising a computer-readable program code embodied therein for diagnosing a vehicle battery cell, characterized by the features of claim 8. The computer-readable program code can be executed by one or more computer processors to perform a process that includes detecting that a current is flowing through a current collector of the battery cell, generating a mechanical excitation for the current collector, determining the amplitude of a voltage across the battery cell based on the mechanical excitation, and detecting the presence of a crack or separation of a film of the current collector based on the amplitude of the voltage across the battery cell.

[0019] In addition to one or more of the features described herein, the process also includes determining the time at which the tear or separation of the foil of the current collector occurred.

[0020] In addition to one or more of the features described herein, mechanical excitation is generated via a mechanical excitation unit arranged or positioned on an outer surface of the accumulator cell or of a foil consolidation unit coupled to the accumulator cell, wherein the outer surface comprises one of the following features: an anode tab of the accumulator cell, a cathode tab of the accumulator cell, or a surface in contact with a combination of an anode of the accumulator cell, a current collector at the anode, a foil expansion area of ​​the current collector at the anode, a cathode of the accumulator cell, a current collector at the cathode, a foil expansion area of ​​the current collector at the cathode, or a separator of the accumulator cell.

[0021] In addition to one or more of the features described herein, the mechanical excitation causes a displacement of the foil of the current collector, the displacement of the foil causing the crack or separation to close and open.

[0022] In addition to one or more of the features described herein, the amplitude is determined within a frequency band with a lower limit of greater than or equal to 1 Hertz.

[0023] In addition to one or more of the features described herein, the voltage across the accumulator cell is passed through a high-pass filter or a band-pass filter before being measured by a voltage measuring unit.

[0024] The aforementioned features and advantages, as well as other features and advantages of the invention, are readily apparent from the following detailed description in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Further features, advantages and details are listed only as examples in the following detailed description, which refers to the drawings in which: Fig. 1. A vehicle according to a specific design is illustrated. Fig. 2 illustrates a cell diagnostic environment according to a configuration, Fig. 3 illustrates a computer environment according to a configuration, and Fig. 4 illustrates a flowchart of a procedure for diagnosing a cell according to one embodiment. DETAILED DESCRIPTION

[0026] The following description is for illustrative purposes only. It is understood that in the drawings, corresponding reference numerals denote identical or equivalent parts and features. As used herein, the term "unit" refers to a circuit that may include an application-specific integrated circuit (ASIC), an electronic circuit, a processor (common, dedicated, or group), and memory executing one or more software or firmware programs, a combinational logic circuit, and / or other suitable components that provide the described functionality. Furthermore, the term "module" may refer to one or more algorithms, instruction sets, software applications, or other computer-readable program code that can be executed by a processor to perform the functions, operations, or processes described herein.

[0027] Embodiments of the present invention improve diagnostic methods for accumulator cells by providing a controller that tests a cell by mechanical excitation to detect cracks in a current collector of the cell. In one embodiment, a diagnostic module can control the vibration of a unit designated for mechanical excitation, which can cause a current collector of a cell to begin vibrating. Subsequently, the controller can measure an output voltage of the cell, determine the amplitude of the output voltage, and, based on the determined amplitude, detect damage (e.g., the presence of a crack or separation) to the current collector film.

[0028] One advantage of the described embodiments is that damage to the current collector film of a cell can be diagnosed without damaging the cell. Furthermore, embodiments of the present invention can reduce the equipment required for diagnosing damage to the current collector film. Additionally, embodiments of the present invention can improve the accuracy of damage diagnosis, since high internal resistance or cell aging no longer need to be taken into account, leading to a reduction in false positive results.

[0029] Fig. Figure 1 illustrates a vehicle 100 according to one embodiment. The vehicle 100 comprises a body 102 which can carry a charging port 104, a power supply system 106, a sensor system 108, a drive system 120, a control system 140 and other systems of the vehicle 100 described herein.

[0030] In one embodiment, the vehicle 100 is an internal combustion engine vehicle (ICE), an electric vehicle (EV), or a hybrid electric vehicle (HEV). In the embodiment shown, the vehicle 100 is an HEV that is partially powered by the power supply system 106, which comprises several interconnected battery cells. The power supply system 106 can be charged via the charging port 104, which is connected to a power source (e.g., a power grid, a charging station, another vehicle, or the like).

[0031] The power supply system 106 can be electrically coupled to at least one electric motor arrangement of the drive system 120. In one embodiment, the power supply system 106 is electrically connected to a DC converter unit 110 (e.g., a DC-DC converter) and an inverter unit 112 (e.g., a traction inverter unit). The inverter unit 112 can comprise several inverters that convert DC signals from the power supply system 106 into three-phase AC signals to drive the electric motors of the drive system 120. The power supply system 106 can also be electrically coupled to electronic vehicle systems such as audio systems, display systems, navigation systems, temperature control systems, or the like.

[0032] The sensor system 108 comprises a variety of sensors that are arranged on or integrated into various components of the vehicle 100. In one embodiment, the sensor system 108 is communicatively connected to the controller 140 in order to transmit measurements from the power supply system 106 to the controller 140. The sensor system 108 may include a current sensor, a voltage sensor, a temperature sensor, or the like.

[0033] The drive system 120 can comprise an internal combustion engine system 122 and at least one electric motor arrangement (e.g., a first electric motor 124 and a second electric motor 126). Each component of the drive system 120 can be designed to drive at least one of the wheels 130 of the vehicle 100 via a transmission system coupled to a front axle shaft or a rear axle shaft, which are coupled to a front and rear set of wheels 130, respectively.

[0034] In one embodiment, the control unit 140 is designed to diagnose an accumulator cell of the power supply system 106 and to control the drive system 120 or other systems of the vehicle 100 based on the diagnosis. The control unit is installed in Fig. 2 and Fig. 3. The techniques used to diagnose the power supply system 106 are discussed in more detail in Fig. 4 discussed.

[0035] Fig. Figure 2 illustrates a cell diagnostic environment 200 according to one embodiment. In the illustrated embodiment, the cell diagnostic environment 200 comprises a test unit 202 (which includes a cell 204, a unit 216 for mechanical excitation, an electrical load 222, a high-pass filter 218, and a voltage measuring unit 220) and the control unit 140. Embodiments of the present invention may relate to a lithium-ion cell. However, any accumulator cell comprising a current collector may be used according to aspects of the embodiments described herein.

[0036] In one embodiment, the cell 204 is a lithium-ion cell of the power supply system 106. The cell 204 can comprise a first current collector (e.g., the current collector 206), an anode 208, a separator 210, a cathode 212, and a second current collector (e.g., the current collector 214).

[0037] The first current collector can be located at the anode 208 and the second current collector can be located at the cathode 212. The anode 208 can be a lower-potential pole of the cell 204, comprising carbon-graphite layers that store lithium atoms, and the cathode 212 can be a higher-potential pole of the cell 204, comprising a lithium metal oxide.

[0038] The current collectors can comprise metal foils or grids that bridge electrons from electrochemical reactions within the cell 204 and the test unit 202. In one embodiment, the first current collector includes a foil extension area 207. The foil extension area 207 can represent a portion of the first current collector that extends beyond an electrode body (e.g., the anode 208 or the cathode 212) of the cell 204. Although not shown in the illustrated embodiment, further foil extension areas can extend from each end of the first current collector and the second current collector.

[0039] In one embodiment, the current collector 206 collects electrons at the anode 208 and transfers the electrons through an anode tab (not shown), through elements of the test unit 202, and through a cathode tab (not shown) to the cathode 212 and to the current collector 214. In another embodiment, the current collectors can transfer electrons through the drive system 120 or other electrical systems of the vehicle 100.

[0040] The separator 210 can comprise a non-conductive, semi-permeable insulator and an electrolyte material or solution that allows the passage of lithium ions while blocking the passage of electrons. In one embodiment, solvent molecules in the electrolyte combine with lithium ions passing through the separator 210 to form a solid electrolyte interface (SEI) at the anode 208. The SEI can prevent direct contact between the electrolyte and the electrons, thus preventing the electrons from decomposing the electrolyte.

[0041] In one embodiment, the mechanical excitation unit 216 is a vibration motor physically connected to the cell 204. In the illustrated embodiment, the mechanical excitation unit 216 is arranged on the film expansion area 207 of the first current collector. However, the mechanical excitation unit 216 can be arranged or positioned on any outer surface of the cell 204 that causes movement or vibration of the current collector. For example, the mechanical excitation unit 216 can be positioned on the anode tab, the cathode tab, or along any surface in contact with any combination of the first current collector, the film expansion area 207, the anode 208, the separator 210, the cathode 212, or the second current collector. The mechanical excitation unit 216 can also be located on a film consolidation unit (e.g.,a terminal or consolidation weld seam) that is coupled to the film expansion area 207, may be arranged or positioned. For example, the unit 216 intended for mechanical excitation may be positioned on a consolidation weld seam that is connected to several film expansion areas at one end of the cell 204.

[0042] The electrical consumer 222 can represent the load of the vehicle 100 on the cell 204, such as the audio systems, display systems, navigation systems, temperature control systems or other electrical systems of the vehicle 100.

[0043] The high-pass filter 218 can be used to filter a direct current (DC) component of an electrical signal, while allowing all components of the electrical signal with a frequency higher than the cutoff frequency of the high-pass filter 218 to pass through. In one embodiment, the high-pass filter 218 comprises a combination of inverters, capacitors, or resistors that filter a DC component of an electrical signal generated by the current collector 206 during mechanical excitation of the current collector 206.

[0044] The voltage measuring unit 220 can comprise a voltage sensor (e.g., a voltage sensor of sensor system 108), a multimeter, a voltmeter, an oscilloscope, or the like. In one embodiment, the voltage measuring unit 220 is connected in series with the high-pass filter 218, and the combination of the voltage measuring unit 220 and the high-pass filter 218 is connected in parallel with the cell 204 and the electrical load 222.

[0045] In the illustrated embodiment, the controller 140 is communicatively coupled to the voltage measuring unit 220 and the unit 216 intended for mechanical excitation. The controller 140 can be configured to control a vibration of the unit 216 intended for mechanical excitation, which can cause the first current collector to begin vibrating. Subsequently, the controller 140 can (via the voltage measuring unit 220) measure an output voltage of the cell 204 and detect damage (e.g., the presence of a tear or separation) to the foil of the first current collector. The controller 140 is in Fig. 3 further described.

[0046] Although the illustrated embodiment shows a single cell of the test unit 202, several cells can also be connected in parallel to cell 204 to form a cell group. The techniques disclosed herein can be applied to the cell group. Although some embodiments of the present invention discuss the detection of damage to the foils of the first current collector, the methods described herein can also be carried out additionally or alternatively on the second current collector to detect damage to the foil of the second current collector. Further techniques for diagnosing cell 204 are also described herein. Fig. 4 described.

[0047] Fig. Figure 3 illustrates a computer environment 300 according to one embodiment. In the illustrated embodiment, the computer environment 300 comprises the controller 140, a network 330, and the test unit 202.

[0048] In one embodiment, the controller 140 comprises a processor 302, which receives instructions and data via a bus 322 from a main memory 304 or a data storage 308. Not all components of the controller 140 are shown. The controller 140 is generally controlled by an operating system (OS) capable of performing or supporting the functions or processes disclosed herein. The processor 302 is a programmable logic device that executes instructions as well as logical and mathematical operations and can represent one or more CPUs. The processor can execute one or more algorithms, instruction sets, or applications in the main memory 304 or the data storage 308 to perform the functions or processes described herein.

[0049] The main memory 304 and the data storage 308 can represent hard disk drives, solid-state drives, flash memory devices, optical media, and the like. Memory 308 can also include structured storage (e.g., a database). Furthermore, main memory 304 and data storage 308 can be considered storage devices physically located elsewhere. For example, main memory 304 and data storage 308 can be physically located on another computer that is communicatively coupled to the controller 140 via bus 322 or network 330.

[0050] The controller 140 can be connected to other computers (e.g., controllers, distributed databases, servers, or web hosts) or the test unit 202 via a network interface 320 and the network 330. Examples of the network 330 include a controller area network (CAN), a transmission control protocol bus (TCP bus), electrical buses, physical transmission cables, optical transmission fibers, wireless transmission media, routers, firewalls, switches, gateway computers, edge servers, a local area network, a wide area network, a wireless network, or the like. The network interface 320 can be any type of network communication device that allows the controller 140 to communicate with computers and other components of the computer environment 300 via the network 330.

[0051] In the illustrated embodiment, the main memory 304 includes a diagnostic module 306. In one embodiment, the diagnostic module 306 represents one or more algorithms, instruction sets, software applications, or other computer-readable program codes that can be executed by the processor 302 to perform the functions, operations, or processes described herein.

[0052] In one embodiment, the diagnostic module 306 generates a signal that causes the cell 204 to begin vibrating via the unit 216, which is designed for mechanical excitation. The resulting voltages of the cell 204 are measured, and these voltages are stored as measurement data 310 in the data storage device 308. The diagnostic module 306 can also determine the resistances of the cell 204 and the amplitude of the voltages or resistances, which the diagnostic module 306 can use to detect damage to the current collector foils of the cell 204. Subsequently, if the current collector foils are damaged, the diagnostic module 306 can control the vehicle 100, generate a cell status report, or perform similar actions. The operation of the diagnostic module 306 is further described herein. Fig. 4 described.

[0053] Fig.Figure 4 illustrates a flowchart of a procedure 400 for diagnosing a cell according to one embodiment. The procedure 400 begins in block 402.

[0054] In block 404, the diagnostic module 306 detects a current through a current collector of a battery cell. In one embodiment, the diagnostic module 306 performs the procedure 400 when it detects that a constant current is flowing through the cell 204. For example, the procedure 400 can be performed while the cell 204 is discharging.

[0055] In block 406, the diagnostic module 306 generates a mechanical excitation of the current collector. In one embodiment, the diagnostic module 306 generates a signal that causes the unit 216, which is responsible for the mechanical excitation, to generate a vibration at the first current collector of cell 204.

[0056] If the first current collector has a crack or a separation in the current collector foil, the vibration of the mechanical excitation unit 216 can, in one embodiment, cause a displacement of the current collector foil, which may cause the crack or separation to close or open. If the crack or separation is closed, the current flow through the elements of the test unit 202 may increase. If the crack or separation is open, the current flow through the elements of the test unit 202 may decrease. Furthermore, the vibrations may cause the crack or separation to open and close rapidly, which may lead to transient voltage spikes that can be measured by the voltage measuring unit 220.

[0057] In block 408, the diagnostic module 306 determines the amplitude of a voltage across the accumulator cell based on mechanical excitation. In one embodiment, the diagnostic module 306 determines the amplitude of the voltage spikes resulting from the rapid opening and closing of the crack or the separation of the current collector film.

[0058] In one embodiment, the high-pass filter 218 can filter the DC voltage generated by the cell 204, enabling the voltage measuring unit 220 to measure the voltage changes (e.g., voltage peaks) generated by the cell 204. In one embodiment, the amplitude is determined within a frequency band with a lower cutoff frequency of 1 Hertz or greater. Furthermore, the test unit 202 can include a band-pass filter with a center frequency matched to the frequency of a vibration of the mechanical excitation unit 216, in order to isolate electrical signals reflecting the vibration frequencies and to filter out high-frequency and low-frequency electrical noise. The diagnostic module 306 can also store timestamps corresponding to the voltage measurements.

[0059] In block 410, the diagnostic module 306 determines, based on the voltage amplitude across the accumulator cell, whether a crack or separation of a current collector film is present. In one configuration, the amplitude can be compared to a damage threshold approaching 0 V (e.g., 10 -15 V). If it is determined that the amplitude exceeds the threshold (i.e., if it is determined that cell 204 has changes in output voltage due to mechanical excitation), the diagnostic module 306 determines that the current collector film has a crack or separation.

[0060] In one embodiment, the procedure 400 is carried out continuously. In this way, the diagnostic module 306 can identify a timestamp corresponding to the detection of the tear or separation of the film, and thereby determine the time at which the tear or separation occurred.

[0061] In one embodiment, the diagnostic module 306 generates a status report for cell 204 upon detecting a crack or separation of a current collector film in cell 204. In another embodiment, the diagnostic module 306 generates a message to notify a user of vehicle 100 that the cell contains a crack or separation of a current collector film. In yet another embodiment, the diagnostic module 306 controls an action (e.g., braking or stopping the vehicle) of vehicle 100 to prevent the use of cell 204 with the damaged current collector film. Method 400 ends in block 412.

Claims

[1] System for diagnosing a battery cell (204) of a vehicle (100), comprising: a processor (302) and a working memory (304) or data storage (308) comprising an algorithm or computer instructions which, when executed by the processor (302), perform an operation comprising: Determine that a current flows through a current collector (206, 214) of the accumulator cell (204), Generating a mechanical excitation of the current collector (206, 214), Determining the amplitude of a voltage across the accumulator cell (204) based on mechanical excitation, and Determining the presence of a crack or separation of a foil of the current collector (206, 214) on the basis of the amplitude of the voltage across the accumulator cell (204). [2] System according to claim 1, wherein the process further comprises: Determining the time at which the tear or separation of the foil of the current collector (206, 214) occurred. [3] System according to claim 1, wherein the mechanical excitation is generated via a unit designated for mechanical excitation which is arranged or positioned on an outer surface of the accumulator cell (204) or a film consolidation unit coupled to the accumulator cell (204). [4] System according to claim 3, wherein the outer surface comprises one of the following features: an anode tab of the accumulator cell (204), a cathode tab of the accumulator cell (204) or a surface that is in contact with a combination of an anode (208) of the accumulator cell (204), a current collector (206) on the anode (208), a foil expansion area of ​​the current collector (206) on the anode (208), a cathode (212) of the accumulator cell (204), a current collector (214) on the cathode (212), a foil expansion area of ​​the current collector (214) on the cathode (212) or a separator (210) of the accumulator cell (204). [5] System according to claim 1, wherein the mechanical excitation causes a displacement of the foil of the current collector (206, 214), wherein the displacement of the foil causes the crack or separation to close and open. [6] System according to claim 5, wherein the amplitude is determined within a frequency band with a lower limit of greater than or equal to 1 Hertz. [7] System according to claim 1, wherein the voltage across the accumulator cell (204) is passed through a high-pass filter (218) or a band-pass filter before being measured by a voltage measuring unit (220). [8] A computer-readable storage medium containing a computer-readable program code embodied therein, wherein the computer-readable program code can be executed by one or more computer processors (302) to perform a diagnostic operation for an accumulator cell (204) of a vehicle (100), the operation comprising: Determine that a current flows through a current collector (206, 214) of the accumulator cell (204), Generating a mechanical excitation of the current collector (206, 214), Determining the amplitude of a voltage across the accumulator cell (204) based on mechanical excitation and Determining the presence of a crack or separation of a foil of the current collector (206, 214) on the basis of the amplitude of the voltage across the accumulator cell (204). [9] Computer-readable storage medium according to claim 8, wherein the process further comprises: Determining the time at which the tear or separation of the foil of the current collector (206, 214) occurred. [10] Computer-readable storage medium according to claim 8, wherein the mechanical excitation is generated via a unit designated for mechanical excitation, which is arranged or positioned on an outer surface of the accumulator cell (204) or of a film strengthening unit coupled to the accumulator cell (204), and wherein the outer surface comprises one of the following features: an anode tab of the accumulator cell (204), a cathode tab of the accumulator cell (204), or a surface covered with a combination of an anode (208) of the accumulator cell (204), a current collector (206) on the anode (208), a film expansion area of ​​the current collector (206) on the anode (208), a cathode (212) of the accumulator cell (204), a current collector (214) on the cathode (212), or a film expansion area of ​​the current collector (214) on the cathode (212) or a separator (210) of the accumulator cell (204).

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