Battery cluster fault diagnosis method and device, terminal equipment and storage medium

Abstract

The application discloses a battery cluster fault diagnosis method, comprising: obtaining a target temperature of a target battery cluster; determining a target impedance spectrum curve corresponding to the target temperature in a preset curve library, wherein the preset curve library comprises impedance spectrum curves corresponding to different temperatures, each impedance spectrum curve is obtained according to an alternating current excitation current of different frequencies, and the alternating current excitation current of different frequencies is obtained from an external power grid; and obtaining a fault diagnosis result of the target battery cluster according to the target impedance spectrum curve. The application also discloses a battery cluster fault diagnosis device, a terminal device and a storage medium. According to the method, the target impedance spectrum curve is excited by an AC / AC alternating current, which can reduce disturbance to a direct current system, increase test reliability, make the accuracy of the target impedance spectrum curve higher, and further make the accuracy of the obtained fault diagnosis result higher.

Description

Technical Field

[0001] This invention relates to the field of battery testing technology, and in particular to a method, apparatus, terminal device, and storage medium for diagnosing faults in battery clusters. Background Technology

[0002] A battery cluster is composed of multiple battery modules connected in series and parallel. The batches of cells in a battery cluster may differ, and the initial capacity and impedance of each cell may also have slight differences. These factors have a significant impact on the impedance of each battery cluster. If they are not identified and diagnosed, they will lead to serious consequences.

[0003] In related technologies, an energy storage converter integrates the DC power of the battery cluster into AC power through a battery management system to charge and discharge the battery cluster. During the charging and discharging process, impedance detection is performed on the battery cluster to further determine the fault diagnosis results of the battery cluster.

[0004] However, the accuracy of impedance detection of battery clusters using existing methods is low, resulting in low accuracy of fault diagnosis results for battery clusters. Summary of the Invention

[0005] The main objective of this invention is to provide a method, apparatus, terminal device, and storage medium for fault diagnosis of battery clusters, aiming to solve the technical problem that the accuracy of impedance detection of battery clusters is low in the existing technology, resulting in low accuracy of fault diagnosis results for battery clusters.

[0006] To achieve the above objectives, this invention proposes a fault diagnosis method for battery clusters, the method comprising the following steps:

[0007] Obtain the target temperature of the target battery cluster;

[0008] The target impedance spectrum curve corresponding to the target temperature is determined from the preset curve library. The preset curve library includes impedance spectrum curves corresponding to different temperatures. Each impedance spectrum curve is obtained based on AC excitation current of different frequencies, which are obtained from the external power grid.

[0009] Based on the target impedance spectrum curve, the fault diagnosis results of the target battery cluster are obtained.

[0010] Optionally, the target impedance spectrum curve includes multiple target impedance spectrum curves; the step of obtaining the fault diagnosis result of the target battery cluster based on the target impedance spectrum curve includes:

[0011] Each target impedance spectrum curve is divided into a first impedance spectrum curve corresponding to the high-frequency impedance region and a second impedance spectrum curve corresponding to the low-frequency impedance region to obtain multiple first impedance spectrum curves and multiple second impedance spectrum curves.

[0012] Based on multiple first impedance spectrum curves, the high-frequency impedance region is analyzed to obtain the first impedance analysis results;

[0013] Based on multiple second impedance spectrum curves, the low-frequency impedance region is analyzed to obtain second impedance analysis results.

[0014] The fault diagnosis result is obtained based on the first impedance analysis result and the second impedance analysis result.

[0015] Optionally, the step of analyzing the high-frequency impedance region based on multiple first impedance spectrum curves to obtain first impedance analysis results includes:

[0016] Based on multiple first impedance spectrum curves, the impedance change trend information corresponding to the high-frequency impedance region is obtained;

[0017] If the impedance change trend information is increasing, then based on the impedance change trend information, a first impedance change rate within a first preset time period and a second impedance change rate within a second preset time period are determined, wherein the first preset time period is longer than the second preset time period.

[0018] The first impedance analysis result is obtained based on the first impedance change rate and the second impedance change rate.

[0019] Optionally, the step of analyzing the low-frequency impedance region based on multiple second impedance spectrum curves to obtain second impedance analysis results includes:

[0020] Determine the fitting semicircles of multiple second impedance spectrum curves;

[0021] When the diameter of the fitted semicircle is in an increasing state, it is determined whether there is a region in the fitted semicircle where the diameter growth rate is greater than the first preset diameter growth rate within a third preset time period.

[0022] If the region of rapid diameter growth exists, then the target diameter growth rate of the semicircle diameter within the fourth preset time period is determined in the fitted semicircle, wherein the third preset time period is greater than the fourth preset time period.

[0023] The second impedance analysis result is obtained based on the target diameter growth rate.

[0024] Optional,

[0025] When the first impedance change rate is greater than or equal to the first preset impedance change rate, and the target battery cluster exhibits cell aging, the first impedance analysis result includes information on the degree of aging of the target battery cluster; or,

[0026] When the first impedance change rate is greater than or equal to the first preset impedance change rate, and the target battery cluster has not shown cell aging, the first impedance analysis result includes connector failure and / or early fatigue of the solder joints in the target battery cluster; or,

[0027] When the second impedance change rate is less than the second preset impedance change rate, the first impedance analysis result includes an increase in the electrolyte impedance in the target battery cluster; or,

[0028] When the second impedance change rate is greater than or equal to the third preset impedance change rate, the first impedance analysis result includes an internal short circuit in the cell of the target battery cluster, and the third preset impedance change rate is greater than the second preset impedance change rate; or...

[0029] When the second impedance change rate is less than the third preset impedance change rate, and greater than or equal to the second preset impedance change rate, the first impedance analysis result includes accelerated cell aging or the occurrence of micro-short circuits in the target battery cluster.

[0030] Optionally, after determining whether there exists a region of rapid diameter growth in the fitted semicircle where the diameter growth rate is greater than the first preset diameter growth rate within a third preset time period, the method further includes:

[0031] If the region of rapid diameter growth does not exist, then determine whether the high-frequency internal resistance of the target battery cluster increases;

[0032] If the high-frequency internal resistance of the target battery cluster increases, then based on the high-frequency internal resistance increase information of the target battery cluster, the fault diagnosis result of the target battery cluster is obtained, or...

[0033] If the high-frequency internal resistance of the target battery cluster does not increase, the fault diagnosis result of cell aging of the target battery cluster is obtained.

[0034] Optionally, the step of obtaining the second impedance analysis result based on the target diameter growth rate includes:

[0035] When the target diameter growth rate is less than the third preset diameter growth rate, a second impedance analysis result showing normal reaction impedance in the target battery cluster is obtained; or,

[0036] When the target diameter growth rate is greater than or equal to the fourth preset diameter growth rate, a second impedance analysis result of slow aging of the cells in the target battery cluster is obtained, wherein the fourth preset diameter growth rate is greater than the third preset diameter growth rate; or,

[0037] When the target diameter growth rate is less than the fourth preset diameter growth rate and greater than or equal to the third preset semicircle diameter growth rate, a second impedance analysis result is obtained showing that the cell aging rate in the target battery cluster is accelerated.

[0038] Optionally, before the step of determining the target impedance spectrum curve corresponding to the target temperature in the preset curve library, the method includes:

[0039] During the operation of the target battery cluster, the operating status information of the target battery cluster is acquired;

[0040] If the operating status information meets the preset conditions, then the operating temperature of the target battery cluster is obtained;

[0041] If the operating temperature matches the preset temperature range, then the preset frequency range of the AC excitation current corresponding to the operating temperature is determined.

[0042] At the operating temperature, based on the operating conditions of the target battery cluster in the preset frequency range, a plurality of preset frequencies are determined in the preset frequency range;

[0043] Based on the multiple preset AC excitation currents corresponding to the multiple preset frequencies and the operating temperature, plot the preset impedance spectrum curve corresponding to the operating temperature;

[0044] Add the preset impedance spectrum curve to the preset curve library.

[0045] Optionally, the step of plotting a preset impedance spectrum curve corresponding to the operating temperature based on multiple preset AC excitation currents corresponding to multiple preset frequencies and the operating temperature includes:

[0046] At the operating temperature, the target battery cluster is excited using each of the preset AC excitation currents to obtain the excitation impedance corresponding to each preset AC excitation current;

[0047] Based on the multiple excitation impedances corresponding to the multiple preset AC excitation currents, a preset impedance spectrum curve corresponding to the operating temperature is plotted.

[0048] Optionally, before the step of adding the preset impedance spectrum curve to the preset curve library, the method further includes:

[0049] Obtain the standard temperature corresponding to the target battery cluster;

[0050] The preset impedance spectrum curve is adjusted according to the standard temperature to obtain the adjusted preset impedance spectrum curve corresponding to the standard temperature.

[0051] The step of adding the preset impedance spectrum curve to the preset curve library includes:

[0052] Add the adjusted preset impedance spectrum curve to the preset curve library.

[0053] Furthermore, to achieve the above objectives, the present invention also proposes a fault diagnosis device for battery clusters, the device comprising:

[0054] The acquisition module is used to acquire the target temperature of the target battery cluster;

[0055] The determination module is used to determine the target impedance spectrum curve corresponding to the target temperature from the preset curve library. The preset curve library includes impedance spectrum curves corresponding to different temperatures. Each impedance spectrum curve is obtained based on AC excitation current of different frequencies, which are obtained from the external power grid.

[0056] The acquisition module is used to obtain the fault diagnosis results of the target battery cluster based on the target impedance spectrum curve.

[0057] Furthermore, to achieve the above objectives, the present invention also proposes a terminal device, the terminal device comprising: a memory, a processor, and a fault diagnosis program for a battery cluster stored in the memory and running on the processor, wherein when the fault diagnosis program for the battery cluster is executed by the processor, it implements the steps of the fault diagnosis method for the battery cluster as described in any of the preceding claims.

[0058] Furthermore, to achieve the above objectives, the present invention also proposes a storage medium storing a fault diagnosis program for a battery cluster, wherein when the fault diagnosis program for the battery cluster is executed by a processor, it implements the steps of the fault diagnosis method for the battery cluster as described in any of the preceding claims.

[0059] The present invention proposes a fault diagnosis method for battery clusters. This method involves obtaining the target temperature of the target battery cluster; determining the target impedance spectrum curve corresponding to the target temperature from a preset curve library, wherein the preset curve library includes impedance spectrum curves corresponding to different temperatures, and each impedance spectrum curve is obtained based on an AC excitation current of different frequencies obtained from an external power grid; and obtaining the fault diagnosis result of the target battery cluster based on the target impedance spectrum curve.

[0060] In existing technologies, DC power is obtained from the target battery cluster itself and then converted into AC excitation current to excite the target battery cluster. However, the coupling process of drawing power from the cluster itself for excitation involves significant disturbances, resulting in low accuracy of impedance detection results and consequently low accuracy of fault diagnosis results. In this invention, AC excitation current is obtained from the external power grid, which reduces disturbances to the DC system, increases test reliability, and improves the accuracy of the target impedance spectrum curve. This, in turn, improves the accuracy of impedance detection results and, consequently, the accuracy of fault diagnosis results. Attached Figure Description

[0061] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0062] Figure 1 This is a schematic diagram of the terminal device structure of the hardware operating environment involved in the embodiments of the present invention;

[0063] Figure 2 This is a flowchart illustrating the first embodiment of the battery cluster fault diagnosis method of the present invention.

[0064] Figure 3 This is a schematic diagram of the energy storage system of the present invention;

[0065] Figure 4 This is a detailed flowchart of step S13 in the second embodiment of the battery cluster fault diagnosis method of the present invention;

[0066] Figure 5 This is a schematic diagram of the curve for fitting a semicircle according to the present invention;

[0067] Figure 6 This is a schematic diagram of the diagnostic process for the high-frequency impedance region of this invention;

[0068] Figure 7 This is a schematic diagram of the diagnostic process for the low-frequency impedance region of the present invention;

[0069] Figure 8 This is a structural block diagram of the first embodiment of the fault diagnosis device for battery clusters of the present invention.

[0070] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0071] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0072] Reference Figure 1 , Figure 1 This is a schematic diagram of the terminal device structure of the hardware operating environment involved in the embodiments of the present invention.

[0073] Typically, a terminal device includes at least one processor 301, a memory 302, and a battery cluster fault diagnosis program stored in the memory and executable on the processor, the battery cluster fault diagnosis program being configured to implement the steps of the battery cluster fault diagnosis method as described above.

[0074] Processor 301 may include one or more processing cores, such as a quad-core processor or an octa-core processor. Processor 301 may be implemented using at least one hardware form selected from DSP (Digital Signal Processing), FPGA (Field-Programmable Gate Array), and PLA (Programmable Logic Array). Processor 301 may also include a main processor and a coprocessor. The main processor, also known as a CPU (Central Processing Unit), is used to process data in the wake-up state; the coprocessor is a low-power processor used to process data in the standby state. In some embodiments, processor 301 may integrate a GPU (Graphics Processing Unit), which is responsible for rendering and drawing the content to be displayed on the screen. Processor 301 may also include an AI (Artificial Intelligence) processor, which is used to handle the operation of the battery cluster fault diagnosis method, enabling the battery cluster fault diagnosis method model to learn autonomously, improving efficiency and accuracy.

[0075] The memory 302 may include one or more storage media, which may be non-transitory. The memory 302 may also include high-speed random access memory and non-volatile memory, such as one or more disk storage devices or flash memory devices. In some embodiments, the non-transitory storage media in the memory 302 are used to store at least one instruction, which is executed by the processor 301 to implement the battery cluster fault diagnosis method provided in the method embodiments of this application.

[0076] In some embodiments, the terminal may also optionally include a communication interface 303 and at least one peripheral device. The processor 301, memory 302, and communication interface 303 can be connected via a bus or signal line. Each peripheral device can be connected to the communication interface 303 via a bus, signal line, or circuit board. Specifically, the peripheral device includes at least one of a radio frequency circuit 304, a display screen 305, and a power supply 306.

[0077] The communication interface 303 can be used to connect at least one I / O (Input / Output) related peripheral device to the processor 301 and the memory 302. In some embodiments, the processor 301, the memory 302, and the communication interface 303 are integrated on the same chip or circuit board; in some other embodiments, any one or two of the processor 301, the memory 302, and the communication interface 303 can be implemented on separate chips or circuit boards, which is not limited in this embodiment.

[0078] The radio frequency (RF) circuit 304 is used to receive and transmit RF (Radio Frequency) signals, also known as electromagnetic signals. The RF circuit 304 communicates with communication networks and other communication devices via electromagnetic signals. The RF circuit 304 converts electrical signals into electromagnetic signals for transmission, or converts received electromagnetic signals back into electrical signals. Optionally, the RF circuit 304 includes: an antenna system, an RF transceiver, one or more amplifiers, a tuner, an oscillator, a digital signal processor, a codec chipset, a user identity module card, etc. The RF circuit 304 can communicate with other terminals through at least one wireless communication protocol. This wireless communication protocol includes, but is not limited to: metropolitan area networks (MANs), various generations of mobile communication networks (2G, 3G, 4G, and 5G), wireless local area networks (WLANs), and / or WiFi (Wireless Fidelity) networks. In some embodiments, the RF circuit 304 may also include circuitry related to NFC (Near Field Communication), which is not limited in this application.

[0079] Display screen 305 is used to display a UI (User Interface). This UI may include graphics, text, icons, videos, and any combination thereof. When display screen 305 is a touch display screen, it also has the ability to collect touch signals on or above its surface. These touch signals can be input as control signals to processor 301 for processing. In this case, display screen 305 can also be used to provide virtual buttons and / or a virtual keyboard, also known as soft buttons and / or a soft keyboard. In some embodiments, display screen 305 can be a single screen, the front panel of an electronic device; in other embodiments, display screen 305 can be at least two screens, respectively disposed on different surfaces of the electronic device or in a folded design; in still other embodiments, display screen 305 can be a flexible display screen, disposed on a curved or folded surface of the electronic device. Furthermore, display screen 305 can also be configured as a non-rectangular, irregular shape, i.e., a non-rectangular screen. Display screen 305 can be made of materials such as LCD (Liquid Crystal Display) or OLED (Organic Light-Emitting Diode).

[0080] Power supply 306 is used to supply power to various components in an electronic device. Power supply 306 can be AC ​​power, DC power, a disposable battery, or a rechargeable battery. When power supply 306 includes a rechargeable battery, the rechargeable battery can support wired or wireless charging. The rechargeable battery can also be used to support fast charging technology.

[0081] Those skilled in the art will understand that Figure 1 The structure shown does not constitute a limitation on the terminal device and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0082] Furthermore, embodiments of the present invention also propose a storage medium storing a fault diagnosis program for a battery cluster. When executed by a processor, the fault diagnosis program for the battery cluster implements the steps of the fault diagnosis method for the battery cluster described above. Therefore, it will not be repeated here. Additionally, the beneficial effects of using the same method will not be repeated here either. For technical details not disclosed in the storage medium embodiments of this application, please refer to the description of the method embodiments of this application. As an example, program instructions can be deployed to execute on a single terminal device, or on multiple terminal devices located in one location, or on multiple terminal devices distributed in multiple locations and interconnected via a communication network.

[0083] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0084] Based on the above hardware structure, an embodiment of the fault diagnosis method for battery clusters of the present invention is proposed.

[0085] Reference Figure 2 , Figure 2 This is a flowchart illustrating the first embodiment of the battery cluster fault diagnosis method of the present invention. The method includes the following steps:

[0086] Step S11: Obtain the target temperature of the target battery cluster.

[0087] It should be noted that the executing entity of this invention is a terminal device, which is equipped with a battery cluster fault diagnosis program. When the terminal device executes the battery cluster fault diagnosis program, it implements the steps of the battery cluster fault diagnosis method of this invention. The target battery cluster is a battery cluster that undergoes impedance detection, typically a lithium battery as the target battery cell, and the temperature at which the target battery cluster undergoes impedance detection is the target temperature.

[0088] Reference Figure 3 , Figure 3 This is a schematic diagram of the energy storage system of the present invention. The energy storage system includes multiple battery cells. Figure 3 A battery cell consists of multiple packs within a box, an AC / AC (alternating current to alternating current) converter, and a BMS (battery management system). Each battery cell is connected to the energy storage inverter of the energy storage system to enable the inverter to control multiple battery cells.

[0089] exist Figure 3 In the diagram, dashed lines represent control lines, while solid lines with arrows represent power lines. Multiple battery cells can be controlled via control lines, and excitation current can be provided to multiple battery power sources individually via power lines.

[0090] The battery cluster is composed of multiple battery modules connected in series and parallel. The total positive and total negative of the battery cluster are connected to the bus. The AC / AC converter and the total positive and total negative form an inner loop. Impedance spectrum detection is performed by injecting excitation current.

[0091] Step S12: Determine the target impedance spectrum curve corresponding to the target temperature in the preset curve library. The preset curve library includes impedance spectrum curves corresponding to different temperatures. Each impedance spectrum curve is obtained based on AC excitation current of different frequencies. The AC excitation current of different frequencies is obtained from the external power grid through AC / AC conversion.

[0092] In this invention, the preset curve library includes impedance spectrum curves for various temperatures. The impedance spectrum curve corresponding to the target temperature is the target impedance spectrum curve. Each impedance spectrum curve is obtained based on AC excitation current of different frequencies. That is, the target impedance spectrum curve is also obtained based on AC excitation current of different frequencies.

[0093] The impedance spectrum curve determined based on the target temperature is the target impedance spectrum curve. Then, based on the target impedance spectrum curve, the fault diagnosis result of the target battery cluster is directly determined. When obtaining the target impedance spectrum curve, the excitation current is obtained from the external power grid, not from the battery cluster itself, and there is a separate excitation circuit. This results in a high accuracy of the obtained target impedance spectrum curve, and consequently, a high accuracy of the fault diagnosis result obtained using the target impedance spectrum curve.

[0094] Furthermore, before the step of determining the target impedance spectrum curve corresponding to the target temperature in the preset curve library, the method includes: acquiring the operating status information of the target battery cluster during its operation; if the operating status information meets preset conditions, acquiring the operating temperature of the target battery cluster; if the operating temperature matches a preset temperature range, determining a preset frequency range of the AC excitation current corresponding to the operating temperature; at the operating temperature, determining multiple preset frequencies in the preset frequency range based on the operating conditions of the target battery cluster in the preset frequency range; plotting a preset impedance spectrum curve corresponding to the operating temperature based on the multiple preset AC excitation currents corresponding to the multiple preset frequencies and the operating temperature; and adding the preset impedance spectrum curve to the preset curve library.

[0095] Operating status information refers to the specific operating status information of the target battery cluster, including information such as power and current. The operating status information meets the preset conditions when the power and current of the target battery cluster during charging and discharging are low, or when the target battery cluster is not in the configuration or calibration state.

[0096] The operating temperature of the target battery cluster refers to the temperature at which the target battery cluster is plotted during the pre-set impedance spectrum curve drawing process (in this invention, multiple operating temperatures are typically defined, with each operating temperature corresponding to a pre-set impedance spectrum curve). The process of plotting the pre-set impedance spectrum curve can be understood as an experimental process; therefore, the operating temperature can also be called the experimental temperature. When plotting the pre-set impedance spectrum curve, the temperature of the target battery cluster needs to be adjusted to the corresponding operating temperature. The pre-set temperature range can be set by the user based on their needs; this invention does not impose specific limitations. When the operating temperature matches the pre-set temperature range (the operating temperature is within the pre-set temperature range), the target battery cluster can perform the pre-set impedance spectrum curve plotting process; when the operating temperature does not match the pre-set temperature range, the target battery cluster cannot perform the pre-set impedance spectrum curve plotting process.

[0097] The preset frequency range can be set by the user based on their needs. This invention does not limit the preset frequency range. For different operating temperatures, the preset frequency range may be different. One operating temperature corresponds to a preset frequency range.

[0098] For each operating temperature, it is necessary to determine the frequency values ​​that are least affected by other factors in the corresponding preset frequency range based on the actual operating conditions of the target battery cluster in the corresponding preset frequency range. These frequency values ​​that are least affected by other factors are the multiple preset frequencies at that operating temperature. Each operating temperature will correspond to multiple preset frequencies, and the multiple preset frequencies corresponding to each operating temperature may be different.

[0099] Then, based on the multiple preset AC excitation currents corresponding to multiple preset frequencies and the operating temperature, a preset impedance spectrum curve corresponding to the operating temperature is plotted. The plotted preset impedance spectrum curve is then added to the preset curve library so that the impedance spectrum curve in the preset curve library can be directly used when the impedance of the target battery is subsequently detected.

[0100] Specifically, the step of plotting a preset impedance spectrum curve corresponding to the operating temperature based on multiple preset AC excitation currents corresponding to multiple preset frequencies and the operating temperature includes: at the operating temperature, stimulating the target battery cluster using each preset AC excitation current and frequency point to obtain the excitation impedance corresponding to each preset AC excitation current and frequency; and plotting the preset impedance spectrum curve corresponding to the operating temperature based on the multiple excitation impedances corresponding to the multiple preset AC excitations.

[0101] For the target battery cluster, after the target battery cluster is installed and the energy storage system corresponding to the target battery cluster is commissioned, multiple initial impedance spectrum curves are plotted for each operating temperature using the above method. Then, the average value of the multiple initial impedance spectrum curves corresponding to each operating temperature is calculated to obtain the corresponding final initial impedance spectrum curve. This final initial impedance spectrum curve also needs to be added to the preset curve library. This final initial impedance spectrum curve is the preset impedance spectrum curve of the initial state corresponding to the target battery cluster.

[0102] Then, at different times of operation of the target battery cluster (in this invention, different times refer to different historical operating times of the target battery cluster before the current time, such as every period of time, every day or every week) or under different specific operating modes of the battery cluster (different specific operating modes refer to different operating conditions under which the target battery cluster can operate normally), continue to draw multiple preset impedance spectrum curves corresponding to different operating temperatures in accordance with the above-described manner of this invention, and add the obtained preset impedance spectrum curves to the preset curve library.

[0103] In the preset curve library, for the same temperature, there will be impedance spectrum curves for different periods. For example, if there are 3 different periods and the preset curve library includes impedance spectrum curves for 3 different temperatures, then the preset curve library will contain 9 impedance spectrum curves.

[0104] Furthermore, before the step of adding the preset impedance spectrum curve to the preset curve library, the method further includes: obtaining a standard temperature corresponding to the target battery cluster; adjusting the preset impedance spectrum curve according to the standard temperature to obtain an adjusted preset impedance spectrum curve corresponding to the standard temperature; the step of adding the preset impedance spectrum curve to the preset curve library includes: adding the adjusted preset impedance spectrum curve to the preset curve library.

[0105] Based on the above description, the operating temperature is the temperature of the determined experimental process. The preset impedance spectrum curve corresponding to the operating temperature may not be applicable to the operating state of the target battery cluster. It is necessary to determine the standard temperature corresponding to the operating state of the target battery cluster, adjust the preset impedance spectrum curve corresponding to the operating temperature to the preset impedance spectrum curve of the standard temperature, and then add the adjusted preset impedance spectrum curve to the preset curve library. Typically, the target impedance spectrum curve obtained in the preset curve library is the adjusted preset impedance spectrum curve obtained through the above adjustment process.

[0106] Typically, when adjusting the preset impedance spectrum curve for the operating temperature, linear interpolation or other methods can be used; this invention does not limit the methods used. For example, based on the preset impedance spectrum curves corresponding to operating temperatures of 35 degrees and 40 degrees, linear interpolation is performed to obtain the impedance spectrum curve corresponding to the standard temperature of 37 degrees.

[0107] Step S13: Obtain the fault diagnosis result of the target battery cluster based on the target impedance spectrum curve.

[0108] Using the determined target impedance spectrum curve, impedance detection is performed on the target battery cluster to obtain fault diagnosis results. Because the target impedance spectrum curve has high accuracy, the fault diagnosis results for the target battery cluster also have high accuracy.

[0109] Typically, after obtaining the fault diagnosis results, the fault diagnosis results need to be output. The on-site maintenance personnel will then confirm the results on-site to obtain the final test results of the target battery cluster (e.g., the ultimate cause of impedance changes).

[0110] In some embodiments, the fault diagnosis results and the final test results confirmed by on-site testing can also be backed up to the cloud for subsequent impedance testing optimization and upgrades, and for more comprehensive analysis and diagnosis by back-end staff.

[0111] The present invention proposes a fault diagnosis method for battery clusters. This method involves obtaining the target temperature of the target battery cluster; determining the target impedance spectrum curve corresponding to the target temperature from a preset curve library, wherein the preset curve library includes impedance spectrum curves corresponding to different temperatures, and each impedance spectrum curve is obtained based on an AC excitation current of different frequencies obtained from an external power grid; and obtaining the fault diagnosis result of the target battery cluster based on the target impedance spectrum curve.

[0112] In existing technologies, DC power is obtained from the target battery cluster itself and then converted into AC excitation current to excite the target battery cluster. However, the coupling process of drawing power from the cluster itself for excitation involves significant disturbances, resulting in low accuracy of impedance detection results and consequently low accuracy of fault diagnosis results. In this invention, AC excitation current is obtained from the external power grid, which reduces disturbances to the DC system, increases test reliability, and improves the accuracy of the target impedance spectrum curve. This, in turn, improves the accuracy of impedance detection results and, consequently, the accuracy of fault diagnosis results.

[0113] Reference Figure 4 , Figure 4 This is a detailed flowchart illustrating step S13 of the second embodiment of the battery cluster fault diagnosis method of the present invention. Step S13 includes:

[0114] Step S21: Divide each target impedance spectrum curve into a first impedance spectrum curve corresponding to the high-frequency impedance region and a second impedance spectrum curve corresponding to the low-frequency impedance region to obtain multiple first impedance spectrum curves and multiple second impedance spectrum curves.

[0115] It is understood that, according to the above method of the present invention, the preset impedance spectrum curves corresponding to the target battery cluster at different times are obtained. For a target temperature, there will be multiple preset impedance spectrum curves corresponding to different operating periods. That is, the determined target impedance spectrum curves also include multiple ones. The different operating periods are all historical operating periods before the current time. Therefore, the target impedance spectrum curve is also called the historical impedance spectrum curve.

[0116] For each target impedance spectrum curve, based on the point where the imaginary part of the curve is a constant 'a' (a can be 0 or other constants), each target impedance spectrum curve is divided into a first impedance spectrum curve corresponding to the high-frequency impedance region and a second impedance spectrum curve corresponding to the low-frequency impedance region. One target impedance spectrum curve corresponds to one first impedance spectrum curve and one second impedance spectrum curve.

[0117] The high-frequency impedance region mainly corresponds to high-frequency impedance, which mainly includes fixed impedance and electrolyte impedance. Fixed impedance includes the impedance of the battery module connectors and the impedance during the welding process between the battery cell and the aluminum-palladium alloy, and is mainly in the form of ohmic impedance. Electrolyte impedance is the impedance of lithium ions in the electrolyte. Since the battery cluster is composed of multiple battery modules, the proportion of ohmic impedance is relatively large. Therefore, the high-frequency impedance region in this invention is mainly described as ohmic impedance. If the ohmic impedance fluctuates repeatedly and generally shows an upward trend, it is mainly due to the looseness of the connectors or some situation before the fatigue failure of the solder joints. Due to the vibration problem during system operation, the high-frequency impedance will fluctuate repeatedly. At this time, the main thing to check is whether the fastening of the connectors is good. If the connection is not a problem, the possibility of fatigue failure of the solder joints inside the battery module should be considered. This can be checked by checking the voltage of each battery module.

[0118] The low-frequency impedance region corresponds to low-frequency impedance, which mainly refers to reaction impedance, including the change value of the battery module in the battery cluster during the charging and discharging process; if this change value increases, it can be understood as the reaction process impedance increasing.

[0119] Step S22: Analyze the high-frequency impedance region based on multiple first impedance spectrum curves to obtain first impedance analysis results.

[0120] Multiple first impedance spectrum curves correspond to different operating periods. The multiple first impedance spectrum curves are arranged according to the operating period (i.e., arranged according to the order in which the first impedance spectrum curves were obtained), and the changing trends of the multiple first impedance spectrum curves are statistically analyzed to obtain the first impedance analysis results based on the changing trends.

[0121] Specifically, the step of analyzing the high-frequency impedance region based on multiple first impedance spectrum curves to obtain a first impedance analysis result includes: obtaining impedance change trend information corresponding to the high-frequency impedance region based on multiple first impedance spectrum curves; if the impedance change trend information is increasing, determining a first impedance change rate within a first preset time period and a second impedance change rate within a second preset time period based on the impedance change trend information, wherein the first preset time period is longer than the second preset time period; and obtaining the first impedance analysis result based on the first impedance change rate and the second impedance change rate.

[0122] Based on the different operating periods corresponding to multiple first impedance spectrum curves, the impedance change over time in the high-frequency impedance region is determined—the impedance change trend information.

[0123] The first preset duration and the second preset duration can be values ​​set by the user based on their needs. This invention does not limit them. Generally, the first preset duration is longer than the second preset duration. The first preset duration is set to be longer and can be understood as a longer duration, while the second preset duration is set to be shorter and can be understood as a shorter duration.

[0124] When the impedance change trend information does not show an increasing trend, it is determined that the impedance of the high-frequency impedance region is normal. When the impedance change information shows an increasing trend, the steps of determining the first impedance change rate within a first preset time period and the second impedance change rate within a second preset time period are performed based on the impedance change trend information.

[0125] Specifically, when the first impedance change rate is greater than or equal to the first preset impedance change rate, and the target battery cluster exhibits cell aging, the first impedance analysis result includes information on the degree of aging of the target battery cluster; or, when the first impedance change rate is greater than or equal to the first preset impedance change rate, and the target battery cluster does not exhibit cell aging, the first impedance analysis result includes connector failure and / or early fatigue of solder joints in the target battery cluster; or, when the second impedance change rate is less than the second preset impedance change rate, the first impedance analysis result includes an increase in electrolyte impedance in the target battery cluster; or, when the second impedance change rate is greater than or equal to the third preset impedance change rate, the first impedance analysis result includes an internal short circuit in the cells of the target battery cluster, and the third preset impedance change rate is greater than the second preset impedance change rate; or, when the second impedance change rate is less than the third preset impedance change rate, but greater than or equal to the second preset impedance change rate, the first impedance analysis result includes accelerated cell aging or the appearance of micro-short circuits in the target battery cluster. Whether the cells of the target battery cluster are aged can be determined by the second impedance analysis result in the low-frequency impedance region.

[0126] For the first impedance change rate corresponding to the first preset duration (the longer duration), a corresponding analysis process can be performed. For the second impedance change rate corresponding to the second preset duration (the shorter duration), a corresponding analysis process can be performed. The analysis processes for the first and second impedance change rates can be performed simultaneously, or the analysis process for the first impedance change rate can be performed first, followed by the analysis process for the second impedance change rate, or the analysis process for the second impedance change rate can be performed first, followed by the analysis process for the first impedance change rate. Then, the results corresponding to the first and second impedance change rates are combined to obtain the final first impedance analysis result.

[0127] For example, the first impedance change rate is greater than or equal to the first preset impedance change rate, and the target battery cluster shows cell aging. At the same time, the second impedance change rate is greater than or equal to the third preset impedance change rate. The first impedance analysis result includes two pieces of information: the aging degree information of the target battery cluster, and the short circuit in the cell of the target battery cluster.

[0128] In this invention, the first preset impedance change rate, the second preset impedance change rate, and the third preset impedance change rate can be set by the user based on their needs, and this invention does not limit them.

[0129] Step S23: Analyze the low-frequency impedance region based on multiple second impedance spectrum curves to obtain the second impedance analysis results.

[0130] It should be noted that the analysis steps for the high-frequency impedance region and the low-frequency impedance region can be performed simultaneously without any specific order. That is, steps S22 and S23 can be executed at the same time so as to obtain the corresponding first impedance analysis results and second impedance analysis results simultaneously.

[0131] Multiple second impedance spectrum curves correspond to different operating periods. The multiple second impedance spectrum curves are arranged according to the operating period (i.e., arranged according to the order in which the preset impedance spectrum curves corresponding to the second impedance spectrum curves are obtained), and the changing trends of the multiple second impedance spectrum curves are statistically analyzed to obtain the second impedance analysis results based on the changing trends.

[0132] Specifically, the step of analyzing the low-frequency impedance region based on multiple second impedance spectrum curves to obtain a second impedance analysis result includes: determining a fitted semicircle of multiple second impedance spectrum curves; when the diameter of the fitted semicircle is in an increasing state, determining whether there is a rapidly growing diameter region in the fitted semicircle where the diameter growth rate is greater than the first preset diameter growth rate within a third preset time period; if the rapidly growing diameter region exists, determining a target diameter growth rate within the fitted semicircle for a fourth preset time period, wherein the third preset time period is greater than the fourth preset time period; and obtaining the second impedance analysis result based on the target diameter growth rate.

[0133] Multiple second impedance spectrum curves are arranged according to the operating period, and the changing trends of multiple second impedance spectrum curves are statistically analyzed to obtain a fitted semicircle. The fitted semicircle is the representation of the changing trends of multiple second impedance spectrum curves.

[0134] The third preset duration, the fourth preset duration, and the first preset diameter growth rate can be values ​​set by the user based on their needs, and this invention does not impose any limitations. The third preset duration is longer than the fourth preset duration. The third preset duration is set to be longer and can be understood as a longer duration, while the fourth preset duration is set to be shorter and can be understood as a shorter duration, similar to the first and second preset durations mentioned above.

[0135] When the diameter of the fitted semicircle does not increase, the impedance of the low-frequency impedance region is determined to be normal. When the diameter of the fitted semicircle shows an increasing trend, it is determined whether there is a rapidly growing diameter region in the fitted semicircle where the diameter growth rate is greater than the first preset diameter growth rate within a third preset time period. That is, the rapidly growing diameter region refers to the region in the fitted semicircle where the diameter growth rate is greater than or equal to the first preset diameter growth rate over a long period of time.

[0136] If the region of rapid diameter growth does not exist, then determine whether the high-frequency internal resistance of the target battery cluster has increased; if the high-frequency internal resistance of the target battery cluster has increased, then obtain the fault diagnosis result of the target battery cluster based on the high-frequency internal resistance growth information of the target battery cluster; or, if the high-frequency internal resistance of the target battery cluster has not increased, obtain the fault diagnosis result of cell aging of the target battery cluster.

[0137] If there is a region of rapid diameter growth, the following steps are performed: the target diameter growth rate of the semicircle within the fourth preset time period is determined in the fitted semicircle. The target diameter growth rate refers to the diameter growth rate in a short period of time.

[0138] Specifically, the step of obtaining the second impedance analysis result based on the target diameter growth rate includes: obtaining a second impedance analysis result indicating normal reaction impedance in the target battery cluster when the target diameter growth rate is less than a third preset diameter growth rate; or, obtaining a second impedance analysis result indicating slow aging of the cells in the target battery cluster when the target diameter growth rate is greater than or equal to a fourth preset diameter growth rate, wherein the fourth preset diameter growth rate is greater than the third preset diameter growth rate; or, obtaining a second impedance analysis result indicating accelerated aging of the cells in the target battery cluster when the target diameter growth rate is less than the fourth preset diameter growth rate and greater than or equal to the third preset semicircle diameter growth rate.

[0139] The third and fourth preset diameter growth rates can be set by the user based on their needs, and this invention does not impose any limitations on them.

[0140] Reference Figure 5 , Figure 5 This is a schematic diagram of the curve for fitting a semicircle according to the present invention. Figure 5 The data includes the abnormal curve corresponding to the abnormal cell and the normal curve corresponding to the normal cell. Both the normal curve and the abnormal curve have corresponding approximate semicircular regions, which are called fitted semicircles.

[0141] Step S24: Obtain the fault diagnosis result based on the first impedance analysis result and the second impedance analysis result.

[0142] Based on the above method, the corresponding first impedance analysis results and second impedance analysis results need to be obtained to obtain the fault diagnosis results. The fault diagnosis results integrate the first impedance analysis results in the high-frequency impedance region and the second impedance analysis results in the low-frequency impedance region.

[0143] Reference Figure 6 , Figure 6 This is a schematic diagram of the diagnostic process for the high-frequency impedance region of this invention.

[0144] First, determine whether the impedance change trend in the high-frequency impedance region fluctuates up and down in the short term and the overall trend is upward. If so, it can be determined that there is a fault diagnosis result of connector failure and / or fatigue failure of solder joint in the high-frequency impedance region. Among them, the impedance change trend needs to meet two conditions: fluctuating up and down in the short term and the overall trend is upward.

[0145] If not, determine whether the impedance change trend in the high-frequency impedance region is increasing; if not, determine that the impedance in the low-frequency impedance region is normal; if so, determine the first impedance change rate and the second impedance change rate (determined in the manner described above, which will not be repeated here).

[0146] Then, a judgment step is performed to determine whether the first impedance change rate is greater than or equal to the first preset impedance change rate; wherein, the first impedance change rate can refer to the impedance change rate over a relatively long period of time; when the first impedance change rate is less than the first preset impedance change rate, it is determined that the impedance in the low-frequency impedance region is normal; when the first impedance change rate is greater than or equal to the first preset impedance change rate, it is further determined whether the target battery cluster has cell aging; if so, the obtained fault diagnosis result includes information on the degree of cell aging of the target battery cluster; if not, the obtained fault diagnosis result includes connector failure and / or early fatigue of the welding points of the target battery cluster.

[0147] Simultaneously, the relationship between the second impedance change rate and the second preset impedance change rate and the third preset impedance change rate is determined to obtain the corresponding fault diagnosis results: when the second impedance change rate is less than the second preset impedance change rate, the first impedance analysis result includes an increase in the electrolyte impedance in the target battery cluster; or, when the second impedance change rate is greater than or equal to the third preset impedance change rate, the first impedance analysis result includes an internal short circuit in the cell of the target battery cluster, and the third preset impedance change rate is greater than the second preset impedance change rate; or, when the second impedance change rate is less than the third preset impedance change rate and greater than or equal to the second preset impedance change rate, the first impedance analysis result includes accelerated cell aging or the occurrence of a micro-short circuit in the target battery cluster.

[0148] Reference Figure 7 , Figure 7 This is a schematic diagram of the diagnostic process for the low-frequency impedance region of this invention.

[0149] First, determining the fitted semicircle means determining the fitted semicircles of multiple second impedance spectrum curves, and then determining whether the diameter is in an increasing state; if not, the data is invalid and deleted, and the data can be reacquired to continue determining the fitted semicircle; if so, it is determined whether the growth rate of the diameter within the third preset time period is greater than the growth rate of the first preset diameter.

[0150] If so, it indicates that there exists a rapidly growing diameter region within the fitted semicircle where the diameter growth rate is greater than the first preset diameter growth rate within a third preset time period. Then, the target diameter growth rate within a fourth preset time period is determined within the fitted semicircle, where the third preset time period is longer than the fourth preset time period. It is worth noting that the third preset time period can represent a longer duration, and the fourth preset time period can represent a shorter duration; that is, the rapidly growing diameter region can refer to a diameter growth region within a longer duration, and the target diameter growth rate can refer to the diameter growth rate within a shorter duration.

[0151] Based on the target diameter growth rate, the second impedance analysis result is obtained, specifically including: when the target diameter growth rate is less than the third preset diameter growth rate, a second impedance analysis result indicating normal reaction impedance in the target battery cluster is obtained; or, when the target diameter growth rate is greater than or equal to the fourth preset diameter growth rate, a second impedance analysis result indicating slow aging of the cells in the target battery cluster is obtained, wherein the fourth preset diameter growth rate is greater than the third preset diameter growth rate; or, when the target diameter growth rate is less than the fourth preset diameter growth rate and greater than or equal to the third preset semicircle diameter growth rate, a second impedance analysis result indicating accelerated aging of the cells in the target battery cluster is obtained.

[0152] If so, it means that there is no region in the fitted semicircle where the diameter growth rate is greater than the first preset diameter growth rate within the third preset time period. Continue to determine whether the high-frequency internal resistance of the target battery increases. If the high-frequency internal resistance of the target battery cluster increases, obtain the fault diagnosis result of the target battery cluster based on the high-frequency internal resistance growth information of the target battery cluster. Or, if the high-frequency internal resistance of the target battery cluster does not increase, obtain the fault diagnosis result of cell aging of the target battery cluster.

[0153] This invention can extend the testing of both new energy storage systems and existing systems. By adding an AC / AC converter, a small current can be introduced during the testing process to minimize the impact on the operation of the battery cluster system. Furthermore, it has no impact on the system when it is not in operation.

[0154] By plotting the impedance spectrum curves of the battery clusters, we can not only reflect the quality of the multiple parallel battery cluster systems controlled by the energy storage converter, but also provide an effective basis for subsequent consistency judgment. Furthermore, by filtering the impedance of the entire battery cluster, we can determine whether the problem is due to the connection or welding part or the aging of the battery cell itself. If it is due to the aging of the battery cell, it also has good guiding significance for the subsequent health status.

[0155] A method combining historical data (impedance spectrum curves from different operating periods) for long-term and short-term analysis was proposed. This method not only identifies the gradual changes in the battery cluster system but also provides early warnings of some aging conditions that may suddenly change, enabling a comprehensive assessment of the operation and health status of the battery cluster.

[0156] After identifying the corresponding causes, the results of the two methods are compared and verified in conjunction with the on-site investigation by maintenance personnel, and all results are uploaded to the cloud. This not only allows for the correction of the algorithm but also enables the iteration of the real causes found on-site into the next generation of products.

[0157] Reference Figure 6 , Figure 6This is a structural block diagram of a first embodiment of the battery cluster fault diagnosis device of the present invention. The device is used in a terminal device and, based on the same inventive concept as the foregoing embodiments, includes:

[0158] Acquisition module 10 is used to acquire the target temperature of the target battery cluster;

[0159] The determination module 20 is used to determine the target impedance spectrum curve corresponding to the target temperature in the preset curve library. The preset curve library includes impedance spectrum curves corresponding to different temperatures. Each impedance spectrum curve is obtained based on AC excitation current of different frequencies, which are obtained from the external power grid.

[0160] The module 30 is used to obtain the fault diagnosis result of the target battery cluster based on the target impedance spectrum curve.

[0161] It should be noted that since the steps performed by the device in this embodiment are the same as those in the aforementioned method embodiments, the specific implementation methods and the technical effects that can be achieved can be referred to the aforementioned embodiments, and will not be repeated here.

[0162] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for fault diagnosis of battery clusters, characterized in that, The method includes the following steps: Obtain the target temperature of the target battery cluster; The target impedance spectrum curve corresponding to the target temperature is determined from the preset curve library. The preset curve library includes impedance spectrum curves corresponding to different temperatures. Each impedance spectrum curve is obtained based on AC excitation current of different frequencies, which are obtained from the external power grid. Based on the target impedance spectrum curve, the fault diagnosis results of the target battery cluster are obtained; Each target impedance spectrum curve is divided into a first impedance spectrum curve corresponding to a high-frequency impedance region and a second impedance spectrum curve corresponding to a low-frequency impedance region, to obtain multiple first impedance spectrum curves and multiple second impedance spectrum curves; the fault diagnosis results include the first impedance analysis results of the high-frequency impedance region and the second impedance analysis results of the low-frequency impedance region; the first impedance analysis results are determined at least based on the impedance change trend of the high-frequency impedance region, and the second impedance analysis results are determined at least based on the fitted semicircles of multiple second impedance spectrum curves.

2. The method as described in claim 1, characterized in that, The target impedance spectrum curve includes multiple target impedance spectrum curves; The step of obtaining the fault diagnosis result of the target battery cluster based on the target impedance spectrum curve includes: Based on multiple first impedance spectrum curves, the high-frequency impedance region is analyzed to obtain the first impedance analysis results; Based on multiple second impedance spectrum curves, the low-frequency impedance region is analyzed to obtain second impedance analysis results. The fault diagnosis result is obtained based on the first impedance analysis result and the second impedance analysis result.

3. The method as described in claim 2, characterized in that, The step of analyzing the high-frequency impedance region based on multiple first impedance spectrum curves to obtain first impedance analysis results includes: Based on multiple first impedance spectrum curves, the impedance change trend information corresponding to the high-frequency impedance region is obtained; If the impedance change trend information is increasing, then based on the impedance change trend information, a first impedance change rate within a first preset time period and a second impedance change rate within a second preset time period are determined, wherein the first preset time period is longer than the second preset time period. The first impedance analysis result is obtained based on the first impedance change rate and the second impedance change rate.

4. The method as described in claim 3, characterized in that, The step of analyzing the low-frequency impedance region based on multiple second impedance spectrum curves to obtain second impedance analysis results includes: Determine the fitting semicircles of multiple second impedance spectrum curves; When the diameter of the fitted semicircle is in an increasing state, it is determined whether there is a region in the fitted semicircle where the diameter growth rate is greater than the first preset diameter growth rate within a third preset time period. If the region of rapid diameter growth exists, then the target diameter growth rate of the semicircle diameter within the fourth preset time period is determined in the fitted semicircle, wherein the third preset time period is greater than the fourth preset time period. The second impedance analysis result is obtained based on the target diameter growth rate.

5. The method as described in claim 4, characterized in that, When the first impedance change rate is greater than or equal to the first preset impedance change rate, and the target battery cluster shows cell aging, the first impedance analysis result includes information on the degree of aging of the target battery cluster. or, When the first impedance change rate is greater than or equal to the first preset impedance change rate, and the target battery cluster has not shown cell aging, the first impedance analysis result includes connector failure and / or early fatigue of the solder joints of the target battery cluster. or, When the second impedance change rate is less than the second preset impedance change rate, the first impedance analysis result includes an increase in the electrolyte impedance in the target battery cluster; or, When the second impedance change rate is greater than or equal to the third preset impedance change rate, the first impedance analysis result includes a short circuit in the cell of the target battery cluster, and the third preset impedance change rate is greater than the second preset impedance change rate. or, When the second impedance change rate is less than the third preset impedance change rate, and greater than or equal to the second preset impedance change rate, the first impedance analysis result includes accelerated cell aging or the occurrence of micro-short circuits in the target battery cluster.

6. The method as described in claim 5, characterized in that, After determining whether there exists a region of rapid diameter growth in the fitted semicircle where the diameter growth rate is greater than the first preset diameter growth rate within a third preset time period, the method further includes: If the region of rapid diameter growth does not exist, then determine whether the high-frequency internal resistance of the target battery cluster increases; If the high-frequency internal resistance of the target battery cluster increases, then based on the high-frequency internal resistance increase information of the target battery cluster, the fault diagnosis result of the target battery cluster is obtained, or... If the high-frequency internal resistance of the target battery cluster does not increase, the fault diagnosis result of cell aging of the target battery cluster is obtained.

7. The method as described in claim 6, characterized in that, The step of obtaining the second impedance analysis result based on the target diameter growth rate includes: When the target diameter growth rate is less than the third preset diameter growth rate, a second impedance analysis result showing normal reaction impedance in the target battery cluster is obtained; or, When the target diameter growth rate is greater than or equal to the fourth preset diameter growth rate, a second impedance analysis result of slow aging of the cells in the target battery cluster is obtained, wherein the fourth preset diameter growth rate is greater than the third preset diameter growth rate; or, When the target diameter growth rate is less than the fourth preset diameter growth rate and greater than or equal to the third preset diameter growth rate, a second impedance analysis result is obtained showing that the cell aging rate in the target battery cluster is accelerated.

8. The method as described in claim 1, characterized in that, Before the step of determining the target impedance spectrum curve corresponding to the target temperature in the preset curve library, the method includes: During the operation of the target battery cluster, the operating status information of the target battery cluster is acquired; If the operating status information meets the preset conditions, then the operating temperature of the target battery cluster is obtained; If the operating temperature matches the preset temperature range, then the preset frequency range of the AC excitation current corresponding to the operating temperature is determined. At the operating temperature, based on the operating conditions of the target battery cluster in the preset frequency range, a plurality of preset frequencies are determined in the preset frequency range; Based on the multiple preset AC excitation currents corresponding to the multiple preset frequencies and the operating temperature, plot the preset impedance spectrum curve corresponding to the operating temperature; Add the preset impedance spectrum curve to the preset curve library.

9. The method as described in claim 8, characterized in that, The step of plotting a preset impedance spectrum curve corresponding to the operating temperature based on multiple preset AC excitation currents corresponding to multiple preset frequencies and the operating temperature includes: At the operating temperature, the target battery cluster is excited using each of the preset AC excitation currents to obtain the excitation impedance corresponding to each preset AC excitation current; Based on the multiple excitation impedances corresponding to the multiple preset AC excitation currents, a preset impedance spectrum curve corresponding to the operating temperature is plotted.

10. The method as described in claim 8, characterized in that, Before the step of adding the preset impedance spectrum curve to the preset curve library, the method further includes: Obtain the standard temperature corresponding to the target battery cluster; The preset impedance spectrum curve is adjusted according to the standard temperature to obtain the adjusted preset impedance spectrum curve corresponding to the standard temperature. The step of adding the preset impedance spectrum curve to the preset curve library includes: Add the adjusted preset impedance spectrum curve to the preset curve library.

11. A fault diagnosis device for battery clusters, characterized in that, The device includes: The acquisition module is used to acquire the target temperature of the target battery cluster; The determination module is used to determine the target impedance spectrum curve corresponding to the target temperature from the preset curve library. The preset curve library includes impedance spectrum curves corresponding to different temperatures. Each impedance spectrum curve is obtained based on AC excitation current of different frequencies, which are obtained from the external power grid. The acquisition module is used to obtain the fault diagnosis results of the target battery cluster based on the target impedance spectrum curve; Each target impedance spectrum curve is divided into a first impedance spectrum curve corresponding to a high-frequency impedance region and a second impedance spectrum curve corresponding to a low-frequency impedance region, to obtain multiple first impedance spectrum curves and multiple second impedance spectrum curves; the fault diagnosis results include the first impedance analysis results of the high-frequency impedance region and the second impedance analysis results of the low-frequency impedance region; the first impedance analysis results are determined at least based on the impedance change trend of the high-frequency impedance region, and the second impedance analysis results are determined at least based on the fitted semicircles of multiple second impedance spectrum curves.

12. A terminal device, characterized in that, The terminal device includes: a memory, a processor, and a fault diagnosis program for the battery cluster stored in the memory and running on the processor, wherein the fault diagnosis program for the battery cluster, when executed by the processor, implements the steps of the fault diagnosis method for the battery cluster as described in any one of claims 1 to 10.

13. A storage medium, characterized in that, The storage medium stores a fault diagnosis program for the battery cluster, which, when executed by a processor, implements the steps of the fault diagnosis method for the battery cluster as described in any one of claims 1 to 10.

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