Diagnosis method and device of battery system

Abstract

The invention provides a diagnosis method and device for a battery system, and the method comprises the steps: determining a to-be-tested reconfigurable battery pack from a plurality of reconfigurable battery packs which are included in the battery system and are connected with a load according to a current diagnosis period; the reconfigurable battery pack to be tested is formed by connecting a plurality of battery units to be tested in series; controlling each to-be-tested battery unit to discharge until the open-circuit voltage is equal, and disconnecting the connection with the load; inputting excitation current to each to-be-tested battery unit to obtain corresponding voltage response; controlling the to-be-tested reconfigurable battery pack to establish connection with a load, and entering a next diagnosis period until a voltage response corresponding to each to-be-tested battery unit in the battery system is obtained; performing difference degree calculation based on the voltage response corresponding to each to-be-tested battery unit in the battery system to obtain the difference degree between each to-be-tested battery unit; and on the basis of the difference degree between each pair of to-be-tested battery units, a diagnosis result is generated, so that rapid battery system diagnosis is realized on the premise that normal work of the battery system is not interfered.

Description

Technical Field

[0001] This invention relates to the field of battery diagnostic technology, and more specifically to a diagnostic method and apparatus for a battery system. Background Technology

[0002] With the continuous development of "high-efficiency and high-power systems," the role of battery energy storage systems in power systems is becoming increasingly prominent. In traditional battery energy storage systems, battery cells are connected in a fixed series-parallel configuration. This fixed topology results in system performance being limited by the worst-performing battery cell, a phenomenon known as the "weakest link effect." In recent years, dynamically reconfigurable battery energy storage technology has emerged as a new energy storage paradigm. It breaks the traditional fixed series-parallel topology, enhances the proactive nature of the battery system, and can fundamentally eliminate the "weakest link effect" caused by differences in battery cells. However, as a complex system containing a large number of battery cells, the persistent challenge of diagnosing the health of these cells presents a significant challenge to dynamically reconfigurable battery energy storage systems.

[0003] Currently, there are several main methods for diagnosing battery systems: First, there are diagnostic methods based on laboratory electrochemical monitoring. This method involves actual measurement of the battery's internal electrochemical parameters to analyze its health status. While this method is accurate, it requires damaging the battery structure and is difficult to perform during system operation. Second, there are methods based on particle imaging or scanning technology. These methods do not require structural damage but are time-consuming and costly, making them difficult to apply in industrial settings. Additionally, methods using applied load current, such as hybrid pulse power characteristic testing (HPPC) or constant current constant voltage charge-discharge (CCCV) testing, can effectively test battery health. However, these methods can easily cause additional damage to the battery and interfere with the normal operation of the system.

[0004] In summary, how to achieve rapid battery system diagnosis without interfering with the normal operation of the battery system is a problem that urgently needs to be solved. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a method and apparatus for diagnosing a battery system, so as to achieve rapid battery system diagnosis without interfering with the normal operation of the battery system.

[0006] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0007] The first aspect of this invention discloses a diagnostic method for a battery system, the method comprising:

[0008] For the current diagnostic cycle, the reconfigurable battery pack to be tested is determined from the multiple reconfigurable battery packs connected to the load in the battery system; the reconfigurable battery pack to be tested is composed of multiple battery cells to be tested connected in series.

[0009] Control each of the battery cells under test to discharge so that the open-circuit voltage of each battery cell under test is equal to the diagnostic voltage threshold, and control the reconfigurable battery pack under test to disconnect from the load.

[0010] An excitation current is input to each of the battery cells under test, and the voltage response corresponding to each of the battery cells under test is detected.

[0011] The system controls the reconfigurable battery pack under test to establish a connection with the load and enters the next diagnostic cycle until the voltage response corresponding to each battery cell under test in the battery system is obtained;

[0012] The difference is calculated based on the voltage response of each of the battery cells under test in the battery system to obtain the difference between each pair of battery cells under test.

[0013] A diagnostic result is generated based on the degree of difference between each pair of the battery cells under test.

[0014] Optionally, inputting an excitation current to each of the battery cells under test includes:

[0015] based on Determine the excitation current waveform; where, Represents the fundamental frequency. Represents the frequency range index. Indicates the signal amplitude. The symbol represents the sign function, and t represents the sampling time.

[0016] Based on the excitation current waveform, an excitation current is input to each of the battery cells under test.

[0017] Optionally, the step of calculating the difference based on the voltage response of each of the battery cells under test in the battery system to obtain the difference between each pair of battery cells under test includes:

[0018] based on The Euler distance between each pair of the battery cells under test is calculated, and the Euler distance is used as the difference.

[0019] Among them, The distance between battery cell i and battery cell j under test is represented by t, where t represents the sampling time and T represents the total sampling time. This represents the voltage response corresponding to the battery cell i under test. This represents the voltage response corresponding to the battery cell j under test.

[0020] Optionally, generating diagnostic results based on the degree of difference between each pair of the tested battery cells includes:

[0021] The difference between each pair of battery cells under test is normalized to obtain the diagnostic result.

[0022] Optionally, the method further includes:

[0023] Based on the diagnostic results, aged battery cells are selected from each of the battery cells to be tested in the battery system.

[0024] The aged battery cell is disconnected from the other battery cells under test.

[0025] A second aspect of this invention discloses a diagnostic device for a battery system, the device comprising:

[0026] A determination unit is used to determine, for the current diagnostic cycle, a reconfigurable battery pack to be tested from multiple reconfigurable battery packs connected to a load in the battery system; the reconfigurable battery pack to be tested is composed of multiple battery cells to be tested connected in series.

[0027] The first control unit is used to control the discharge of each of the battery cells under test, so that the open circuit voltage of each of the battery cells under test is equal to the diagnostic voltage threshold, and to control the reconfigurable battery pack under test to disconnect from the load.

[0028] The detection unit is used to input an excitation current to each of the battery cells under test and to detect the voltage response corresponding to each of the battery cells under test.

[0029] The second control unit is used to control the reconfigurable battery pack under test to establish a connection with the load and enter the next diagnostic cycle until the voltage response corresponding to each battery cell under test in the battery system is obtained;

[0030] The calculation unit is used to calculate the difference based on the voltage response of each of the battery cells under test in the battery system, so as to obtain the difference between each pair of battery cells under test.

[0031] A diagnostic generation unit is used to generate diagnostic results based on the degree of difference between each pair of the battery cells under test.

[0032] Optionally, the detection unit is specifically used for:

[0033] based on Determine the excitation current waveform; where, Represents the fundamental frequency. Represents the frequency range index. Indicates the signal amplitude. The symbol represents the sign function, and t represents the sampling time.

[0034] Based on the excitation current waveform, an excitation current is input to each of the battery cells under test.

[0035] Optionally, the computing unit is specifically used for:

[0036] based on The Euler distance between each pair of the battery cells under test is calculated, and the Euler distance is used as the difference.

[0037] Among them, The distance between battery cell i and battery cell j under test is represented by t, where t represents the sampling time and T represents the total sampling time. This represents the voltage response corresponding to the battery cell i under test. This represents the voltage response corresponding to the battery cell j under test.

[0038] Optionally, the diagnostic generation unit is specifically used for:

[0039] The difference between each pair of battery cells under test is normalized to obtain the diagnostic result.

[0040] Optionally, the device further includes:

[0041] An analysis unit is configured to, based on the diagnostic results, screen out aged battery cells from the various battery cells under test in the battery system; and control the aged battery cells to disconnect from the other battery cells under test.

[0042] Based on the above-described embodiment of the present invention, a diagnostic method and apparatus for a battery system are provided. For the current diagnostic cycle, a reconfigurable battery pack to be tested is determined from multiple reconfigurable battery packs connected to a load within the battery system. The reconfigurable battery pack to be tested is composed of multiple battery cells connected in series. Each battery cell to be tested is controlled to discharge, such that the open-circuit voltage of each battery cell to be tested is equal to a diagnostic voltage threshold. The reconfigurable battery pack to be tested is then disconnected from the load. An excitation current is input to each battery cell to be tested, and the voltage response corresponding to each battery cell to be tested is detected. The reconfigurable battery pack to be tested is then controlled to establish a connection with the load, and the next diagnostic cycle begins, until the voltage response corresponding to each battery cell to be tested in the battery system is obtained. Based on the voltage responses corresponding to each battery cell to be tested in the battery system, a difference is calculated to obtain the difference between each pair of battery cells to be tested. Based on the difference between each pair of battery cells to be tested, a diagnostic result is generated. In this scheme, only one set of reconfigurable battery packs is connected to the detection circuit, while other reconfigurable battery packs can still maintain normal operation. Furthermore, the fast electrical excitation response method, which obtains voltage response from excitation current, is adopted to improve the diagnostic speed, thereby achieving the goal of rapid battery system diagnosis without interfering with the normal operation of the battery system. Attached Figure Description

[0043] 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 embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0044] Figure 1 This is a topology diagram of a dynamically reconfigurable battery energy storage system disclosed in an embodiment of the present invention;

[0045] Figure 2 This is a schematic diagram of the internal structure of a reconfigurable battery pack disclosed in an embodiment of the present invention;

[0046] Figure 3 This is a flowchart of a battery system diagnostic method disclosed in an embodiment of the present invention;

[0047] Figure 4 This is a structural diagram of a diagnostic device for a battery system disclosed in an embodiment of the present invention. Detailed Implementation

[0048] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] In this application, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0050] As the background technology indicates, current methods for battery system diagnosis mainly include the following: First, diagnostic methods based on laboratory electrochemical monitoring. This method involves actual measurement of the battery's internal electrochemical parameters to analyze its health status. While accurate, this method requires damaging the battery structure and is difficult to perform during system operation. Second, methods based on particle imaging or scanning technology. These methods do not require structural damage but are time-consuming and costly, making them difficult to apply in industrial settings. Additionally, methods using applied load current, such as hybrid pulse power characteristic testing (HPPC) or constant current constant voltage charge-discharge (CCCV) testing, can effectively test battery health. However, these methods can easily cause additional damage to the battery and interfere with the normal operation of the system. In summary, how to achieve rapid battery system diagnosis without interfering with the normal operation of the battery system is a pressing issue that needs to be addressed.

[0051] Therefore, this invention discloses a diagnostic method and apparatus for a battery system. In this solution, only one set of reconfigurable battery packs is connected to the detection circuit, while other reconfigurable battery packs can still maintain normal operation. Furthermore, a fast electrical excitation response method that obtains voltage response from excitation current is adopted, which improves the diagnostic speed and thus achieves the goal of rapid diagnosis of the battery system without interfering with its normal operation.

[0052] like Figure 1 The diagram shown is a topology diagram of a dynamically reconfigurable battery energy storage system disclosed in an embodiment of the present invention. The system includes multiple reconfigurable battery packs and a diagnostic signal generator.

[0053] In this application, the full name of the battery system is dynamically reconfigurable battery energy storage system.

[0054] Each reconfigurable battery pack can be in one of three states: connected to load, connected to diagnostics, or disconnected. Connected to load means the reconfigurable battery pack, either alone or in conjunction with other reconfigurable battery packs, is supplying power to the load. Connected to diagnostics means the reconfigurable battery pack is being diagnosed independently. A reconfigurable battery pack in the disconnected state is not currently operating and is not being diagnosed; this typically occurs when there are significant differences in the states of the reconfigurable battery packs, and the system actively balances these differences.

[0055] The diagnostic signal generator is used to input excitation current to each cell under test in the reconfigurable battery under test.

[0056] like Figure 2 The diagram shown is a schematic diagram of the internal structure of a reconfigurable battery pack disclosed in an embodiment of the present invention.

[0057] It should be noted that each reconfigurable battery pack consists of several battery cells and a controllable switch. Each battery cell is associated with a controllable switch, which effectively controls whether the battery cell is connected to the circuit. Simultaneously, the reconfigurable battery pack also contains a high-speed switch to prevent internal open circuits, ensuring the normal operation of the reconfigurable battery pack. Each battery cell within the reconfigurable battery pack is equipped with a corresponding voltage detection device, capable of accurately measuring the real-time terminal voltage (voltage response) of the battery. Furthermore, existing research has already been able to calculate the open-circuit voltage of the battery cell based on its terminal voltage characteristics.

[0058] Specifically, the high-speed switch needs to be turned on quickly when other switches in the branch are closed to ensure that the battery cell does not short-circuit; at the same time, it also needs to be turned on quickly when all other battery cells in the branch are connected to the reconfigurable battery pack to ensure that the reconfigurable battery pack does not open-circuit.

[0059] In practical engineering, the BTU network card is connected to the battery cell port. This network card contains a switch that controls the battery cell connection and disconnection, as well as voltage detection equipment (such as a voltage sensor).

[0060] When using the fast electric excitation response method to diagnose a battery system, it is necessary to select the reconfigurable battery pack under test and connect each battery cell under test in the selected reconfigurable battery pack under test to the diagnostic signal generator in a pure series connection.

[0061] Before actual diagnostics, the open-circuit voltage of each cell in the reconfigurable battery pack under test needs to be adjusted to be the same, based on the reconfiguration characteristics of the reconfigurable battery pack, to ensure the consistency of the operating points of the battery cells. At this time, since only one reconfigurable battery pack is connected to the diagnostic signal generator, other reconfigurable battery packs can still participate in the external charging and discharging of the system. This also means that the diagnosis of the battery system at this time does not affect the normal operation of the battery system as a whole.

[0062] It should be noted that the curves obtained by battery electrochemical impedance spectroscopy (EIS) testing play an important role in mapping battery health. Based on the EIS testing approach, a diagnostic method for battery systems based on rapid electrical excitation response is proposed.

[0063] like Figure 3 The diagram shown is a flowchart of a battery system diagnostic method disclosed in an embodiment of the present invention. The method is applied to a diagnostic device, which is connected to a diagnostic signal generator.

[0064] This method mainly includes the following steps:

[0065] Step S101: For the current diagnostic cycle, identify the reconfigurable battery pack to be tested from the multiple reconfigurable battery packs connected to the load in the battery system.

[0066] The reconfigurable battery pack under test consists of multiple battery cells connected in series.

[0067] It should be noted that one reconfigurable battery pack is diagnosed in each diagnostic cycle, while other reconfigurable battery packs continue to provide power to the load during that diagnostic cycle until the diagnostics of all reconfigurable battery packs in the battery system are completed, or the diagnostics of the reconfigurable battery pack specified by the user are completed.

[0068] Step S102: Control each battery cell under test to discharge so that the open circuit voltage of each battery cell under test is equal to the diagnostic voltage threshold, and control the reconfigurable battery pack under test to disconnect from the load.

[0069] It should be noted that the impedance spectrum of a battery cell differs at different operating points. Therefore, when performing diagnostics on a reconfigurable battery pack, it is necessary to ensure that the open-circuit voltage of the battery cell under test is the same.

[0070] Step S103: Input excitation current to each battery cell under test and detect the voltage response of each battery cell under test.

[0071] In step S103, an excitation current is input to each battery cell under test through a diagnostic signal generator, and the corresponding voltage response is detected by a voltage detection device corresponding to each battery cell under test.

[0072] It should be noted that a battery cell is generally considered a complex nonlinear system. When considering current as input and voltage as output, the system's output is affected by factors such as the battery's state of charge (SOC), state of health (SOH), and battery temperature. Furthermore, due to the complex electrochemical reactions and kinetic processes within the system, a significant nonlinear response occurs on the voltage side when a current signal is input as excitation, causing considerable analytical difficulties.

[0073] However, for minute timescales and minimal excitations, parameters such as SOC, SOH, and temperature of the battery cell can be considered essentially constant. Furthermore, due to the small excitation size, the battery cell can be approximated as a linear system, and its internal impedance spectrum can be measured. Differences in the impedance spectra can then be compared to identify variations in the battery cells. Traditional impedance spectrum calculation methods require individual measurements of the system response at each excitation frequency, directly resulting in a significant time commitment for traditional impedance spectrum-based battery system diagnostics.

[0074] For traditional impedance spectrum calculations, the inherent relationship can be summarized by the following formula:

[0075]

[0076] To avoid signal division in the time domain, we rearrange the terms to obtain:

[0077]

[0078] In this application, the purpose of the battery system diagnostics is to verify the consistency of the battery system. Therefore, the magnitude of the excitation current can be standardized. In this case, the differences in voltage response of the battery cells within the battery system can be considered to directly reflect the differences in the internal impedance spectrum of the battery cells. In addition, the excitation current should contain multiple frequency information to cover more details of the internal impedance spectrum of the battery power supply; at the same time, it should ensure that the excitation current is small enough not to introduce significant nonlinear effects.

[0079] In specific implementation, based on Determine the excitation current waveform; where, Represents the fundamental frequency (which together with the frequency range). Represents the frequency range index. Indicates the signal amplitude (which can be adjusted according to the battery cell specifications). The sign function is represented by t (output 1 when the input is positive, output -1 when the input is negative, and output 0 when the input is zero), and t represents the sampling time.

[0080] This creates a frequency range of... , 4 , ..., A rectangular wave with controllable amplitude is generated, which is the excitation current waveform. Finally, based on the excitation current waveform, the excitation current is input to each battery cell under test.

[0081] In addition, to ensure the consistency of the input current, all battery cells under test should be connected in pure series. At this point, an excitation current corresponding to the excitation current waveform is generated by a diagnostic signal generator, and the voltage response of the battery cells under electrical excitation conditions is collected by the voltage detection device of the battery cells. Subsequently, by comparing the differences in the voltage responses of the battery cells, the internal consistency of the battery system (i.e., the diagnosis of the battery system) can be achieved.

[0082] Step S104: Control the reconfigurable battery pack under test to establish a connection with the load and enter the next diagnostic cycle until the voltage response corresponding to each battery cell under test in the battery system is obtained.

[0083] Understandably, after the diagnostics of the reconfigurable battery pack under test are completed, it is necessary to reconnect it to the load to ensure that the normal operation of the battery system is not affected.

[0084] Step S105: Calculate the difference based on the voltage response of each battery cell under test in the battery system to obtain the difference between each battery cell under test.

[0085] In the specific implementation, the Euler distance is used to characterize the difference in voltage response, as follows:

[0086] based on The Euler distance between each battery cell under test is calculated and used as the degree of difference.

[0087] Among them, The distance between battery cell i and battery cell j under test is represented by t, where t represents the sampling time and T represents the total sampling time. This represents the voltage response corresponding to the battery cell i under test. This represents the voltage response corresponding to the battery cell j under test.

[0088] Generally speaking, the size of the Euler distance directly reflects the degree of difference between battery cells; that is, the larger the Euler distance, the higher the degree of difference between battery cells.

[0089] Step S106: Generate diagnostic results based on the degree of difference between each battery cell under test.

[0090] In the specific implementation, the Euler distance is normalized to facilitate the consistency analysis of battery cells. That is, the difference between each battery cell under test is normalized to obtain the diagnostic results.

[0091] The normalization method is as follows:

[0092]

[0093] in, This represents the normalized difference between battery cell i and battery cell j under test.

[0094] In one embodiment, based on the diagnostic results, aged battery cells are selected from the various battery cells under test in the battery system; the aged battery cells are then disconnected from the other battery cells under test.

[0095] It should be noted that the closer the Euler distance (difference) between two battery cells is to 1, the higher the difference between the battery cells. This can be observed... By analyzing the internal element size distribution, battery cells that differ significantly from other battery cells within the battery system can be identified, allowing for targeted testing to prevent excessive aging and system failure. Furthermore, the reconfigurable battery system's characteristics can be utilized to remove battery cells with significant differences.

[0096] Based on the battery system diagnostic method disclosed in the above embodiments of the present invention, in this solution, only one set of reconfigurable battery packs is connected to the detection circuit, while other reconfigurable battery packs can still maintain normal operation. Furthermore, a fast electrical excitation response method that obtains voltage response from excitation current is adopted, which improves the diagnostic speed and thus achieves the goal of rapid battery system diagnosis without interfering with the normal operation of the battery system.

[0097] Based on the above-described battery system diagnostic method disclosed in the embodiments of the present invention, such as... Figure 4 The diagram shown is a structural diagram of a diagnostic device for a battery system disclosed in an embodiment of the present invention. The device is applied to diagnostic equipment and includes: a determination unit 401, a first control unit 402, a detection unit 403, a second control unit 404, a calculation unit 405, and a diagnostic generation unit 406.

[0098] The determination unit 401 is used to determine, for the current diagnostic cycle, a reconfigurable battery pack to be tested from multiple reconfigurable battery packs connected to the load in the battery system; the reconfigurable battery pack to be tested is composed of multiple battery cells to be tested connected in series.

[0099] The first control unit 402 is used to control the discharge of each battery cell under test, so that the open circuit voltage of each battery cell under test is equal to the diagnostic voltage threshold, and to control the reconfigurable battery pack under test to disconnect from the load.

[0100] The detection unit 403 is used to input excitation current to each battery cell under test and detect the voltage response of each battery cell under test.

[0101] The second control unit 404 is used to control the reconfigurable battery pack under test to establish a connection with the load and enter the next diagnostic cycle until the voltage response corresponding to each battery cell under test in the battery system is obtained.

[0102] The calculation unit 405 is used to calculate the difference based on the voltage response of each battery cell under test in the battery system, so as to obtain the difference between each battery cell under test.

[0103] The diagnostic generation unit 406 is used to generate diagnostic results based on the degree of difference between each battery cell under test.

[0104] In one embodiment, the detection unit 403 is specifically used for:

[0105] based on Determine the excitation current waveform; where, Represents the fundamental frequency. Represents the frequency range index. Indicates the signal amplitude. The symbol represents the sign function, and t represents the sampling time.

[0106] Based on the excitation current waveform, an excitation current is input to each battery cell under test.

[0107] In one embodiment, the calculation unit 405 is specifically used for:

[0108] based on The Euler distance between each battery cell under test is calculated and used as the degree of difference.

[0109] Among them, The distance between battery cell i and battery cell j under test is represented by t, where t represents the sampling time and T represents the total sampling time. This represents the voltage response corresponding to the battery cell i under test. This represents the voltage response corresponding to the battery cell j under test.

[0110] In one embodiment, the diagnostic generation unit 406 is specifically used for:

[0111] The differences between each battery cell under test are normalized to obtain the diagnostic results.

[0112] In one embodiment, the apparatus further includes:

[0113] The analysis unit is used to screen out aged battery cells from the various battery cells under test in the battery system based on the diagnostic results; and to control the aged battery cells to disconnect from other battery cells under test.

[0114] Based on the battery system diagnostic method disclosed in the above embodiments of the present invention, in this solution, only one set of reconfigurable battery packs is connected to the detection circuit, while other reconfigurable battery packs can still maintain normal operation. Furthermore, a fast electrical excitation response method that obtains voltage response from excitation current is adopted, which improves the diagnostic speed and thus achieves the goal of rapid battery system diagnosis without interfering with the normal operation of the battery system.

[0115] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the descriptions in the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0116] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0117] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A diagnostic method for a battery system, characterized in that, The method includes: For the current diagnostic cycle, the reconfigurable battery pack to be tested is determined from the multiple reconfigurable battery packs connected to the load in the battery system; the reconfigurable battery pack to be tested is composed of multiple battery cells to be tested connected in series. Control each of the battery cells under test to discharge so that the open-circuit voltage of each battery cell under test is equal to the diagnostic voltage threshold, and control the reconfigurable battery pack under test to disconnect from the load. An excitation current is input to each of the battery cells under test, and the voltage response corresponding to each of the battery cells under test is detected. The system controls the reconfigurable battery pack under test to establish a connection with the load and enters the next diagnostic cycle until the voltage response corresponding to each battery cell under test in the battery system is obtained; The difference is calculated based on the voltage response of each of the battery cells under test in the battery system to obtain the difference between each pair of battery cells under test. A diagnostic result is generated based on the degree of difference between each pair of the battery cells under test.

2. The method according to claim 1, characterized in that, The step of inputting excitation current to each of the battery cells under test includes: based on Determine the excitation current waveform; where, Represents the fundamental frequency. Represents the frequency range index. Indicates the signal amplitude. The symbol represents the sign function, and t represents the sampling time. Based on the excitation current waveform, an excitation current is input to each of the battery cells under test.

3. The method according to claim 1, characterized in that, The difference calculation based on the voltage response of each of the battery cells under test in the battery system is used to obtain the difference between each pair of battery cells under test, including: based on The Euler distance between each pair of the battery cells under test is calculated, and the Euler distance is used as the difference. Among them, The distance between battery cell i and battery cell j under test is represented by t, where t represents the sampling time and T represents the total sampling time. This represents the voltage response corresponding to the battery cell i under test. This represents the voltage response corresponding to the battery cell j under test.

4. The method according to claim 1, characterized in that, The process of generating diagnostic results based on the degree of difference between each pair of the tested battery cells includes: The difference between each pair of battery cells under test is normalized to obtain the diagnostic result.

5. The method according to any one of claims 1 to 4, characterized in that, The method further includes: Based on the diagnostic results, aged battery cells are selected from each of the battery cells to be tested in the battery system. The aged battery cell is disconnected from the other battery cells under test.

6. A diagnostic device for a battery system, characterized in that, The device includes: A determination unit is used to determine, for the current diagnostic cycle, a reconfigurable battery pack to be tested from multiple reconfigurable battery packs connected to a load in the battery system; the reconfigurable battery pack to be tested is composed of multiple battery cells to be tested connected in series. The first control unit is used to control the discharge of each of the battery cells under test, so that the open circuit voltage of each of the battery cells under test is equal to the diagnostic voltage threshold, and to control the reconfigurable battery pack under test to disconnect from the load. The detection unit is used to input an excitation current to each of the battery cells under test and to detect the voltage response corresponding to each of the battery cells under test. The second control unit is used to control the reconfigurable battery pack under test to establish a connection with the load and enter the next diagnostic cycle until the voltage response corresponding to each battery cell under test in the battery system is obtained; The calculation unit is used to calculate the difference based on the voltage response of each of the battery cells under test in the battery system, so as to obtain the difference between each pair of battery cells under test. A diagnostic generation unit is used to generate diagnostic results based on the degree of difference between each pair of the battery cells under test.

7. The apparatus according to claim 6, characterized in that, The detection unit is specifically used for: based on Determine the excitation current waveform; where, Represents the fundamental frequency. Represents the frequency range index. Indicates the signal amplitude. The symbol represents the sign function, and t represents the sampling time. Based on the excitation current waveform, an excitation current is input to each of the battery cells under test.

8. The apparatus according to claim 6, characterized in that, The computing unit is specifically used for: based on The Euler distance between each pair of the battery cells under test is calculated, and the Euler distance is used as the difference. Among them, The distance between battery cell i and battery cell j under test is represented by t, where t represents the sampling time and T represents the total sampling time. This represents the voltage response corresponding to the battery cell i under test. This represents the voltage response corresponding to the battery cell j under test.

9. The apparatus according to claim 6, characterized in that, The diagnostic generation unit is specifically used for: The difference between each pair of battery cells under test is normalized to obtain the diagnostic result.

10. The apparatus according to any one of claims 6 to 9, characterized in that, The device further includes: An analysis unit is configured to, based on the diagnostic results, screen out aged battery cells from the various battery cells under test in the battery system; and control the aged battery cells to disconnect from the other battery cells under test.

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