Method and device for screening battery system and control system

Abstract

The embodiment of the invention provides a method and device for screening a battery system and a control system. The battery system comprises a plurality of battery units, and the method comprises the following steps: determining direct-current resistance values x of the plurality of battery units according to a first direct-current resistance value of each battery unit in the plurality of battery units; acquiring a direct-current resistance value y of the battery system; and determining whether the battery system is a qualified battery system according to the ratio of x to y. According to the method, the device and the control system provided by the embodiment of the invention, under the condition that a plurality of battery systems are assembled into a larger battery product, the direct-current resistance difference between the battery systems is reduced, and the overall charge-discharge capacity is improved, so that the overall service life is prolonged.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of batteries, and in particular, to a method, device, and control system for screening a battery system. Background Art

[0002] Due to the requirements of high voltage and large capacity in existing energy storage systems, a large number of batteries need to be assembled in series and parallel into container products and then exchange energy with the power grid through a power conversion system (PCS). During the assembly of the container, due to the poor consistency of the direct current resistance (DCR) between the parallel battery packs, uneven current distribution occurs between the container clusters, affecting the power output of the container system and reducing the overall service life. Summary of the Invention

[0003] In view of this, the embodiments of the present application provide a method, device, and control system for screening a battery system, which is beneficial to reducing the difference in direct current resistance between battery systems when assembling multiple battery systems into a larger battery product, improving the overall charge and discharge capacity, and extending the overall service life.

[0004] In a first aspect, a method for screening a battery system is provided. The battery system includes a plurality of battery cells. The method includes: determining a direct current resistance value x of the plurality of battery cells according to a first direct current resistance value of each battery cell in the plurality of battery cells; obtaining a direct current resistance value y of the battery system; and determining whether the battery system is a qualified battery system according to the ratio of x to y.

[0005] In this embodiment, determining whether the battery system is a qualified battery system according to the proportion of the direct current resistance value x of the plurality of battery cells in the direct current resistance value y of the battery system can quickly screen out battery systems with poor consistency in direct current resistance values. Therefore, when assembling multiple battery systems into a larger battery product, it is beneficial to reduce the difference in direct current resistance values between battery systems, improve the overall charge and discharge capacity, and extend the overall service life. In addition, by obtaining the direct current resistance value of each battery cell, it is also helpful to understand the internal consistency of the battery system, thereby improving the performance of the entire battery system.

[0006] In a possible implementation, the battery system further includes a connecting component. Obtaining the direct current resistance value y of the battery system includes: determining the sum of the direct current resistance value x of the plurality of battery cells and a first resistance value z of the connecting component as the direct current resistance value y of the battery system.

[0007] In this embodiment, by determining the DC resistance value x of multiple battery cells and the first resistance value z of the connection component as the DC resistance value y of the battery system, on the one hand, the resistance of the connection component is considered, and compared with directly taking the DC internal resistance of multiple battery cells as the DC internal resistance of the battery system, the accuracy of the DC internal resistance of the battery system is improved; on the other hand, compared with obtaining the DC internal resistance of the battery system through testing, the production line equipment cost can be saved, and the production capacity can be increased.

[0008] In a possible implementation, the multiple battery cells include M groups of battery cells connected in series, where M is a positive integer greater than 1. Determining the DC resistance value x of the multiple battery cells according to the first DC resistance value of each battery cell in the multiple battery cells includes: determining the DC resistance value of each group of battery cells in the M groups of battery cells according to the first DC resistance value of each battery cell in the multiple battery cells; and determining the sum of the DC resistance values of the M groups of battery cells as the DC resistance value x of the multiple battery cells.

[0009] In this embodiment, when the battery system is formed by connecting multiple groups of battery cells in series, the DC resistance value of the multiple battery cells constituting the battery system can be determined by the sum of the DC resistance values of the multiple groups of battery cells, which can eliminate the influence of measurement errors and individual differences, thereby improving the accuracy of the DC resistance value of the multiple battery cells. In addition, by obtaining the DC resistance value of each group of battery cells, it is helpful to understand the consistency of the DC resistance values of each group of battery cells, thereby improving the performance and lifespan of the entire battery system.

[0010] In a possible implementation, the battery system is an electrical box, and the electrical box includes M groups of battery monomers connected in series.

[0011] In this embodiment, the DC resistance value of the multiple battery monomers in the electrical box is determined by the sum of the DC resistance values of the multiple groups of battery monomers connected in series, without measuring the DC resistance value of the electrical box, which can eliminate the influence of measurement errors and the differences between multiple groups of battery monomers, thereby improving the accuracy of the DC resistance value of the multiple groups of battery monomers. In addition, by obtaining the DC resistance value of each group of battery monomers, it is helpful to understand the balance of the DC resistance values of each group of battery monomers, thereby improving the performance and lifespan of the electrical box.

[0012] In a possible implementation, each group of battery monomers in the M groups of battery monomers includes S battery monomers connected in series, where S is a positive integer.

[0013] In a possible implementation, each group of battery monomers in the M groups of battery monomers includes N battery monomers connected in parallel, where N is a positive integer greater than 1.

[0014] In a possible implementation, the battery system is an electrical cabinet, which includes M groups of electrical boxes connected in series. Each group of the M groups of electrical boxes includes T electrical boxes connected in series, where T is a positive integer.

[0015] In a possible implementation, the method further includes: performing time correction on the second DC resistance value of each battery cell to obtain the first DC resistance value of each battery cell.

[0016] In this embodiment, by performing time correction on the second DC resistance value of the battery cell, determining the first DC resistance value of the battery cell, and determining the DC resistance value x of multiple battery cells in the battery system based on the first DC resistance value, a more accurate DC resistance value can be obtained, providing a reliable basis for the consistency judgment of the DC resistance.

[0017] In a possible implementation, performing time correction on the second DC resistance value of each battery cell to obtain the first DC resistance value of each battery cell includes: correcting the second DC resistance value of each battery cell according to the ratio between the second DC resistance value and the first DC resistance value of the reference battery cell to obtain the first DC resistance value of each battery cell. The first DC resistance value of the reference battery cell is obtained by substituting the storage time of the reference battery cell and the second DC resistance value of the reference battery cell into the first mapping function of the DC resistance value and the storage time.

[0018] In this embodiment, by correcting the first DC resistance value of the obtained battery cell, the first DC resistance value of other battery cells can be obtained quickly and accurately, reducing the calculation amount and improving the processing efficiency of the control system.

[0019] In a possible implementation, performing time correction on the second DC resistance value of each battery cell to obtain the first DC resistance value of each battery cell includes: substituting the storage time of each battery cell and the second DC resistance value of each battery cell into the second mapping function of the DC resistance value and the storage time to obtain the first DC resistance value of each battery cell.

[0020] In this embodiment, by directly substituting the second DC resistance value of the battery cell and the storage time of the battery cell into the relational expression, the first DC resistance value of the battery cell can be accurately obtained and is not affected by other battery cells, and the calculation method is flexible.

[0021] In a possible implementation, the method further includes: performing temperature correction on the second resistance value of the connection component to obtain the first resistance value of the connection component. The second resistance value of the connection component is the test value of the resistance of the connection component at 25°C.

[0022] In this embodiment, calculating the DC resistance value of the battery system based on the resistance value of the connection component after temperature correction can provide a more accurate and reliable basis for the subsequent judgment of the DC resistance consistency of multiple battery systems.

[0023] In a possible implementation manner, performing temperature correction on the second resistance value of the connection component to obtain the first resistance value of the connection component includes: substituting the temperature coefficient of the connection component, the second resistance value of the connection component, and the current ambient temperature into a preset temperature correction function to obtain the first resistance value of the connection component.

[0024] In a second aspect, a device for screening a battery system is provided. The battery system includes multiple battery cells. The device includes: a determination unit for determining the DC resistance value x of multiple battery cells according to the first DC resistance value of each battery cell in the multiple battery cells; an acquisition unit for acquiring the DC resistance value y of the battery system; the determination unit is further configured to: determine whether the battery system is a qualified battery system according to the ratio of x to y.

[0025] In a possible implementation manner, the battery system further includes a connection component. The acquisition unit is specifically configured to: determine the sum of the DC resistance value x of multiple battery cells and the first resistance value z of the connection component as the DC resistance value y of the battery system.

[0026] In a possible implementation manner, the multiple battery cells include M groups of battery cells connected in series, where M is a positive integer greater than 1. The determination unit is specifically configured to: determine the DC resistance value of each group of battery cells in the M groups of battery cells according to the DC resistance value of each battery cell in the multiple battery cells; determine the sum of the DC resistance values of each group of battery cells in the M groups of battery cells as the DC resistance value x of the multiple battery cells.

[0027] In a possible implementation manner, the battery system is an electrical box, and the electrical box includes M groups of battery monomers connected in series.

[0028] In a possible implementation manner, each group of battery monomers in the M groups of battery monomers includes S battery monomers connected in series, where S is a positive integer.

[0029] In a possible implementation manner, each group of battery monomers in the M groups of battery monomers includes N battery monomers connected in parallel, where N is a positive integer greater than 1.

[0030] In a possible implementation manner, the battery system is an electrical cabinet, and the electrical cabinet includes M groups of electrical boxes connected in series. Each group of electrical boxes in the M groups of electrical boxes includes T electrical boxes connected in series, where T is a positive integer.

[0031] In a possible implementation manner, the acquisition unit is further configured to: perform time correction on the second DC resistance value of each battery cell to obtain the first DC resistance value of each battery cell.

[0032] In a possible implementation, the obtaining unit is specifically configured to: correct the second DC resistance value of each battery cell according to the ratio between the second DC resistance value and the first DC resistance value of the reference battery cell, so as to obtain the first DC resistance value of each battery cell, and the first DC resistance value of the reference battery cell is obtained by substituting the storage time of the reference battery cell and the second DC resistance value of the reference battery cell into the first mapping function between the DC resistance value and the storage time.

[0033] In a possible implementation, the obtaining unit is specifically configured to: substitute the storage time of each battery cell and the second DC resistance value of each battery cell into the second mapping function between the DC resistance value and the storage time, and obtain the first DC resistance value of each battery cell.

[0034] In a possible implementation, the obtaining unit is further configured to: perform temperature correction on the second resistance value of the connection component to obtain the first resistance value of the connection component, and the second resistance value of the connection component is the test value of the resistance of the connection component at 25°C.

[0035] In a possible implementation, the obtaining unit is specifically configured to: substitute the temperature coefficient of the connection component, the second resistance value of the connection component, and the current ambient temperature into a preset temperature correction function, and obtain the first resistance value of the connection component.

[0036] In a third aspect, a control system for screening a battery system is provided, including a memory and a processor. The memory is used to store instructions, and the processor is used to read the instructions and execute the method in the first aspect and any possible implementation manner of the first aspect according to the instructions.

[0037] In a fourth aspect, a chip is provided, including a processor, which is used to call and run a computer program from a memory, so that a device installed with the chip executes the method in the first aspect and any possible implementation manner of the first aspect.

[0038] In a fifth aspect, a computer program is provided, and the computer program enables a computer to execute the method in the first aspect and any possible implementation manner of the first aspect.

[0039] In a sixth aspect, a computer-readable storage medium is provided, which is used to store a computer program, and the computer program enables a computer to execute the method in the first aspect and any possible implementation manner of the first aspect.

[0040] In a seventh aspect, a computer program product is provided, including computer program instructions, and the computer program instructions enable a computer to execute the method in the first aspect and any possible implementation manner of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments of the present application. Obviously, the following described drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the drawings.

[0042] Figure 1 Shows the assembly process diagram of the current container.

[0043] Figure 2 Shows a schematic block diagram of the first method for screening a battery system according to an embodiment of the present application.

[0044] Figure 3 Shows a schematic block diagram of the second method for screening a battery system according to an embodiment of the present application.

[0045] Figure 4 Shows an assembly diagram of an electric box according to an embodiment of the present application.

[0046] Figure 5 Shows another assembly diagram of an electric box according to an embodiment of the present application.

[0047] Figure 6 Shows a schematic block diagram of the third method for screening a battery system according to an embodiment of the present application.

[0048] Figure 7 Shows a schematic curve diagram between the DC resistance value of a battery cell and the storage time according to an embodiment of the present application.

[0049] Figure 8 Shows a schematic block diagram of the fourth method for screening a battery system according to an embodiment of the present application.

[0050] Figure 9 Shows a schematic block diagram of the fifth method for screening a battery system according to an embodiment of the present application.

[0051] Figure 10 Shows a schematic curve diagram between the resistance value of a connection component and the temperature according to an embodiment of the present application.

[0052] Figure 11 Shows a schematic flowchart of the method for screening an electric box according to an embodiment of the present application.

[0053] Figure 12 Shows a schematic block diagram of the device for screening a battery system according to an embodiment of the present application.

[0054] Figure 13 Shows a schematic block diagram of the control system for screening a battery system according to an embodiment of the present application. Detailed implementation manners

[0055] The following further describes in detail the implementation manners of the present application in conjunction with the accompanying drawings and embodiments. The detailed descriptions and drawings of the following embodiments are used to exemplarily illustrate the principle of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0056] In the description of the present application, it should be noted that unless otherwise stated, the meaning of "a plurality of" is two or more; the orientation or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", etc. are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not strictly vertical, but within the allowable error range. "Parallel" is not strictly parallel, but within the allowable error range.

[0057] The orientation words appearing in the following description are all the directions shown in the drawings, and do not limit the specific structure of the present application. In the description of the present application, it should also be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0058] The term "and / or" in the present application is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: the existence of A, the simultaneous existence of A and B, and the existence of B. In addition, the character " / " in the present application generally represents an "or" relationship between the front and rear associated objects.

[0059] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs; the terms used in the description of the present application in the specification are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "including" and "having" and any variations thereof in the description, claims, and drawings of the present application are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the description, claims, or drawings of the present application are used to distinguish different objects, rather than to describe a specific order or primary-secondary relationship.

[0060] References to "embodiments" in this application mean that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described in this application can be combined with other embodiments.

[0061] A battery refers to a single physical module that includes one or more battery cells to provide a higher voltage and capacity. For example, a battery can be a battery system. The battery system in this application refers to a battery assembly in which battery cells are connected in series, parallel, or a combination of series and parallel, where a combination of series and parallel means a mixture of series and parallel. For example, the battery system in this application can be an electrical box, and the battery cell is a battery monomer, that is, the electrical box can be formed by connecting multiple battery monomers in series and / or in parallel. Another example is that the battery system in this application can be an electrical cabinet, which can also be called a battery cluster, and the battery cell is an electrical box, that is, the electrical cabinet is formed by connecting multiple electrical boxes in series and / or in parallel.

[0062] Optionally, the battery in the embodiments of this application can be a lithium-ion battery, a lithium-metal battery, a lead-acid battery, a nickel-cadmium battery, a nickel-metal hydride battery, a lithium-sulfur battery, a lithium-air battery, or a sodium-ion battery, etc. The embodiments of this application do not make specific limitations in this regard.

[0063] Currently, due to the requirements of high voltage and large capacity for energy storage systems, a large number of batteries need to be connected in series and parallel to assemble into a container product and then exchange energy with the power grid through a PCS. During the process of assembling the container, due to the problem of the consistency of the DC resistance between the parallel battery clusters, the charge and discharge power of the container system decreases and the overall lifespan decreases.

[0064] In some related technologies, during the process of forming a container, the batteries are grouped according to the DC resistance grading, that is, some batteries with relatively small differences in DC resistance are assembled together. Due to the excessive number of grouping categories, it is difficult to operate and control during the actual production process.

[0065] In view of this, the embodiments of this application provide a method for screening a battery system. The battery system includes multiple battery cells. According to the proportion of the DC resistance value x of the multiple battery cells in the DC resistance value y of the battery system, it is determined whether the battery system is a qualified battery system, which can quickly screen out the battery systems with poor DC resistance consistency. Furthermore, when multiple battery systems are assembled into a larger battery product, it is beneficial to reduce the DC resistance difference between the battery systems, improve the overall charge and discharge capacity, and thus improve the overall lifespan.

[0066] Figure 1 Shows the assembly process diagram of the container. As Figure 1As shown, the battery cell is the smallest unit. An electrical box is assembled from L battery cells, where L is a positive integer greater than 1. A cabinet is assembled from P electrical boxes, where P is a positive integer greater than 1. A container is formed by paralleling Q cabinets, where Q is a positive integer greater than 1.

[0067] It should be understood that the battery system of the embodiments of the present application can be as small as an electrical box, as large as a cabinet, or even a container.

[0068] It should also be understood that the technical solutions in the embodiments of the present application can be applied not only to energy storage batteries but also to power batteries.

[0069] Figure 2 FIG. shows a schematic block diagram of a method 100 for screening a battery system according to an embodiment of the present application. The battery system may include multiple battery units. Optionally, the method 100 may be executed by a control system in the battery automated production and assembly process. For example, the method 100 may be executed by a Manufacturing Execution System (MES). The method 100 may include some or all of the following content.

[0070] S110, determine the DC resistance value x of multiple battery units according to the first DC resistance value of each battery unit in the multiple battery units.

[0071] S120, obtain the DC resistance value y of the battery system.

[0072] S130, determine whether the battery system is a qualified battery system according to the ratio of x to y.

[0073] First, DCR refers to the resistance that the current encounters when flowing through the inside of the battery during operation, including ohmic internal resistance and polarization internal resistance. The ohmic internal resistance is mainly determined by the total conductivity of the battery, while the polarization internal resistance is mainly determined by the solid-phase diffusion coefficient of lithium ions in the electrode active material. Generally, DCR can be calculated by applying a large current to the battery for a short period of time and according to the voltage change of the battery before and after applying the current and the applied current.

[0074] In the embodiments of the present application, the first DCR value of each battery unit can be obtained through testing or other means. For example, if the battery unit is the smallest unit, such as a battery cell, then the first DCR value of the battery unit can only be obtained through testing. For another example, if the battery unit is a non-smallest unit, such as an electrical box or a cabinet, then the first DCR value of the battery unit can be obtained through testing or calculated from the DCR values of smaller battery units included in the battery unit.

[0075] The DCR value x of multiple battery cells refers to the DC internal resistance of multiple battery cells as a whole, which is only related to the first DCR value of each battery cell in the multiple battery cells and has nothing to do with the resistance of any other components in the battery system. That is to say, since a battery system may also include some connection components in addition to multiple battery cells, and these connection components also have a certain resistance, therefore, the DCR value x of multiple battery cells in the embodiments of the present application is not exactly equal to the DCR value y of the battery system.

[0076] In some embodiments, the DCR value y of the battery system can be obtained through testing. In other embodiments, the DCR value y of the battery system can also be calculated based on the internal resistance values of all components included in the battery system. For example, the DCR value y of the battery system can be jointly determined based on the DCR value x of multiple battery cells and the resistance value of the connection components. It should be understood that the embodiments of the present application do not limit the acquisition method of the DCR value y of the battery system.

[0077] In some embodiments, after obtaining the DCR value x of multiple battery cells and the DCR value y of the battery system, the ratio of x to y can be further compared with a preset threshold. Since the resistance of other components in the battery system is relatively stable except for the DCR value of the battery cells, if the ratio of x to y is greater than the preset threshold, it can be considered that the DCR value of the battery system is greatly affected by the DCR value of the battery cells, which also indirectly reflects that the consistency of the DCR values among multiple battery cells in the battery system is poor, and it can be basically determined that the battery system is an unqualified battery system. On the contrary, if the ratio of x to y is not greater than the preset threshold, it can be considered that the DCR value of the battery system is less affected by the DCR value of the battery cells, which also indirectly reflects that the consistency of the DCR values among multiple battery cells in the battery system is good, and it can be basically determined that the battery system is a qualified battery system.

[0078] Optionally, in the case where the battery system is determined to be a qualified battery system, the battery system can be assembled with other qualified battery systems into a larger battery product. In the case where the battery system is determined to be an unqualified battery system, the unqualified battery system is not used to assemble into a larger battery product. When there are enough screened unqualified battery systems, a part of the battery systems with relatively small DCR value differences among multiple unqualified battery systems can also be assembled into a larger battery product.

[0079] In this embodiment, according to the proportion of the DCR value x of multiple battery cells in the DCR value y of the battery system, it is determined whether the battery system is a qualified battery system, which can quickly screen out battery systems with poor DCR value consistency. Furthermore, when multiple battery systems are assembled into a larger battery product, it is beneficial to reduce the difference in DCR values between battery systems and improve the overall lifespan. Additionally, by obtaining the DCR value of each battery cell, it is also helpful to understand the balance inside the battery system, thereby improving the performance of the entire battery system.

[0080] In some embodiments, the battery system further includes a connection component. S120, that is, obtaining the DC resistance value y of the battery system, may include: determining the sum of the DC resistance value x of multiple battery cells and the first resistance value z of the connection component as the DC resistance value y of the battery system.

[0081] Optionally, the connection component in the battery system may include at least one of a busbar component, a fuse, a high-voltage wire harness, and a switch. For example, if the battery system is an electrical box, the electrical box may be formed by connecting multiple battery monomers through a busbar component so that electrical energy can be transmitted between the multiple battery monomers. The electrical box further includes a fuse and a manual maintenance switch for protecting the circuit and preventing abnormal conditions such as overcurrent or overheating from damaging the electrical box. Another example, if the battery system is an electrical cabinet, the electrical cabinet may be composed of multiple electrical boxes connected through a high-voltage wire harness and various functional connection components in the main control box. For example, the functional connection components may include a busbar component, a fuse, a disconnector, a circuit breaker, a current sensor, and a connector, etc.

[0082] For a battery system, the DCR value of the battery system can be decomposed into the DCR value of the battery cell part and the resistance value of other connection components. In the embodiments of the present application, if the first resistance value of other connection components is measurable or can be obtained through calculation, then the DCR value y of the battery system can be the sum of the DCR value x of multiple battery cells and the first resistance value z of the connection component, that is, y = x + z.

[0083] In this embodiment, by determining the DCR value y of the battery system as the sum of the DCR value x of multiple battery cells and the first resistance value z of the connection component, on the one hand, the resistance of the connection component is considered, and compared with directly taking the DC internal resistance of multiple battery cells as the DC internal resistance of the battery system, the accuracy of the DC internal resistance of the battery system is improved; on the other hand, compared with obtaining the DC internal resistance of the battery system through testing, it can save the cost of production line equipment and improve production capacity.

[0084] In some embodiments, the multiple battery cells include M groups of battery cells connected in series, where M is a positive integer greater than 1, such as Figure 3As shown, S110, that is, determining the DC resistance value x of multiple battery cells according to the first DC resistance value of each battery cell in the multiple battery cells, includes: S111, determining the DC resistance value of each group of battery cells in M groups of battery cells according to the first DC resistance value of each battery cell in the multiple battery cells; S112, determining the sum of the DC resistance values of the M groups of battery cells as the DC resistance value x of the multiple battery cells.

[0085] Similar to the DCR value of multiple battery cells, the DC internal resistance of each group of battery cells refers to its DCR value as a whole, which is only related to the first DCR value of the battery cells in each group of battery cells and has nothing to do with the resistance of any other components.

[0086] In this embodiment, when the battery system is formed by connecting multiple groups of battery cells in series, the DCR value of the multiple battery cells that make up the battery system can be determined by the sum of the DCR values of the multiple groups of battery cells, which can eliminate the influence of measurement errors and individual differences, thereby improving the accuracy of the DCR value of the multiple battery cells. In addition, by obtaining the DCR value of each group of battery cells, it helps to understand the balance of the DCR values of each group of battery cells, thereby improving the performance and lifespan of the entire battery system.

[0087] Optionally, the battery system is an electrical box, and the battery cell is a battery monomer, that is, the electrical box can include M groups of battery monomers connected in series.

[0088] In this embodiment, the DCR value of the multiple battery monomers in the electrical box is determined by the sum of the DCR values of the multiple groups of battery monomers connected in series, without measuring the DCR value of the electrical box, which can eliminate the influence of measurement errors and the differences between multiple groups of battery monomers, thereby improving the accuracy of the DCR value of the multiple groups of battery monomers. In addition, by obtaining the DCR value of each group of battery monomers, it helps to understand the balance of the DCR values of each group of battery monomers, thereby improving the performance and lifespan of the electrical box.

[0089] In one embodiment, each group of battery monomers in the M groups of battery monomers includes S battery monomers connected in series, and S is a positive integer.

[0090] For example, as Figure 4 shown, the electrical box is formed by connecting M battery monomers in series, where one battery monomer is divided into a group of battery monomers. Assume that the first DCR value of battery monomer 1 is DCR1, the first DCR value of battery monomer 2 is DCR1, and so on. The first DCR value of battery monomer S is DCRM. The DCR value of the M battery monomers can be calculated by the following formula:

[0091] x = DCR1 + DCR2 +... + DCRM (1).

[0092] In another embodiment, each group of battery monomers in the M groups of battery monomers includes N battery monomers connected in parallel, where N is a positive integer greater than 1.

[0093] For example, as Figure 5 shown, the electrical box is formed by connecting M groups of battery monomers in series, and each group of battery monomers is formed by connecting 2 battery monomers in parallel. Assume that the first DCR value of battery monomer 1 is DCR1, the first DCR value of battery monomer 2 is DCR1, ……, and so on. The first DCR value of battery monomer 2M - 1 is DCR2M - 1, and the first DCR value of battery monomer 2M is DCR2M. Then the DCR values of the 2M battery monomers can be calculated by the following formula:

[0094]

[0095] In other embodiments, the battery system is an electrical cabinet or a battery cluster. The electrical cabinet or the battery cluster includes M groups of electrical boxes connected in series, where each group of electrical boxes in the M groups of electrical boxes includes T electrical boxes connected in series, and T is a positive integer.

[0096] When the electrical cabinet is composed of multiple electrical boxes connected in series, the DCR value x of the multiple electrical boxes can be obtained by calculating using the above formula (1).

[0097] In some embodiments, as Figure 6 shown, method 100 may further include: S140, performing time correction on the second DC resistance value of each battery cell to obtain the first DC resistance value of each battery cell.

[0098] Generally, the DCR value of a battery cell shows an increasing trend with the storage time. From the production of the battery cell to its assembly into a battery system, it needs to go through a period of warehouse storage. The inconsistent storage time results in inconsistent growth of the DCR values of the battery cells. Therefore, the DCR value obtained after the production of the battery cell cannot accurately represent its DCR value when it is assembled into the battery system. It should be understood that the first DCR value and the second DCR value in the embodiments of the present application represent the DCR values obtained at different times, and the time to obtain the second DCR value is earlier than the time to obtain the first DCR value. In addition, the second DCR value may refer to the DCR value obtained at any time during the production process or after the production of the battery cell. Optionally, the second DCR value is the initial DCR value obtained after the production of the battery system.

[0099] When assembling multiple battery cells into a battery system, the control system can control the code scanning device to scan the identifier of the battery system to obtain the second DCR value of the battery cell. By scanning the identifier of the battery system, the time when the second DCR value of the battery cell is obtained can also be traced. When the second DCR value is the initial DCR value, the time when the second DCR value of the battery cell is obtained can also be referred to as the time when the battery cell is put into the warehouse. Combining with the current time, the storage time of the battery cell can be obtained. For example, the storage time of the battery cell = current time - the time when the battery cell is put into the warehouse. After obtaining the storage time of the battery cell and the second DCR value of the battery cell, based on the relational expression stored inside the control system, the first DCR value of the battery cell, which can also be called the current DCR value, can be calculated.

[0100] Generally, a relational expression between the DCR of the battery cell and the storage time of the battery cell can be stored inside the control system. This relational expression can be obtained by the control system executing Method 100 to fit a series of DCR values with different storage times, or it can be obtained from another control system, that is, this relational expression is obtained by another control system fitting a series of DCR values with different storage times, and then sent by the other control system to the control system executing Method 100.

[0101] Optionally, multiple mass-produced battery cells can be selected for storage in a warehouse environment, and a series of different storage days can be selected. Every n days, the same process of DCR tests is performed on multiple battery cells of the same batch, and the average value of the DCR values of multiple battery cells of this batch at the same storage time is obtained to get the DCR values of battery cells with a series of different storage times. Next, the DCR values of battery cells with a series of different storage times are fitted according to "storage days, DCR value" to obtain the relational expression of the DCR value of the battery cell changing with the storage time of the battery cell. Figure 7 The fitting schematic diagram of the DCR value and the storage time of battery cells of the same batch is shown.

[0102] In some embodiments, there is a relational expression between the DCR value and the storage time of battery cells of the same batch, and there may be different relational expressions between the DCR values and the storage times of battery cells of different batches. In other words, when determining the second DCR value of a certain battery cell, first, according to the batch of this battery cell, and further based on the relational expression corresponding to this batch, substituting the storage time of this battery cell, the first DCR value of this battery cell is determined.

[0103] In other embodiments, the DCR values obtained by testing battery cells of different batches at different storage times may also be fitted, that is, a relational expression corresponds to the DCR value of any batch of battery cells and the storage time of the battery cells. In other words, when determining the first DCR value of a certain battery cell, it is not necessary to determine the batch of the battery cell, and directly based on the relational expression stored in the control system, substitute the storage time of the battery cell to determine the first DCR value of the battery cell.

[0104] In this embodiment, the second DCR value of the battery cell is corrected for time to determine the first DCR value of the battery cell, and based on the first DCR value, the DCR values x of multiple battery cells in the battery system are determined, so that more accurate DCR values can be obtained, providing a reliable basis for the consistency judgment of DCR.

[0105] In some embodiments, as Figure 8 shown, S140, that is, correcting the second DC resistance value of each battery cell for time to obtain the first DC resistance value of each battery cell, includes: S141, correcting the second DC resistance value of each battery cell according to the ratio between the second DC resistance value of the reference battery cell and the first DC resistance value of the reference battery cell to obtain the first DC resistance value of each battery cell. The first DC resistance value of the reference battery cell is obtained by substituting the storage time of the reference battery cell and the second DC resistance value of the reference battery cell into the first mapping function of the DC resistance value and the storage time.

[0106] For example, the second DCR value of each battery cell can be corrected for time according to the following formula to obtain the first DCR value of each battery cell:

[0107] R1 = (aD 2 + bD + R0) * R2 / R0 (3).

[0108] Where a and b are constants, R1 is the first DCR value of each battery cell, R2 is the second DCR value of each battery cell, R0 is the second DCR value of the reference battery cell, and D is the storage time of each battery cell.

[0109] That is to say, the second DCR value of one of the battery cells and the storage days of the battery cell can be obtained first, and the first DCR value of the battery cell can be calculated according to the fitting relationship between the DCR value and the storage days. The first DCR values of other battery cells can be obtained by correcting the first DCR value of the previously obtained battery cell. Suppose the first DCR value of the previously obtained battery cell is denoted as DCR1, its second DCR value is denoted as DCR2, the first DCR value of the battery cell currently to be calculated is denoted as DCR3, and its second DCR value is denoted as DCR4. Then DCR3 is calculated by DCR1*DCR4 / DCR2.

[0110] It should be noted that usually during or immediately after the production of the battery cell, the DCR test is carried out, that is, the second DCR value is obtained and bound to the identification of the battery cell. And immediately after the battery cells are assembled into a battery system, the second DCR value is obtained to obtain the DCR value of the battery system and bind it to the identification of the battery system. At the same time, the first DCR value of the battery cell can also be bound to the identification of the battery cell. Therefore, when calculating the first DCR value of a certain battery cell using formula (3), it is necessary to ensure that the reference battery cell is produced or assembled at the same time as this battery cell and assembled into the battery system at the same time.

[0111] For example, the DCR test time of the battery monomers in the same batch on the production line is September 1, 2023, and the time when the battery monomers are assembled into the electric box is September 15, 2023. One of the battery monomers in this batch is used as the reference battery monomer. The second DCR, that is, the initial DCR value, obtained by testing the reference battery monomer on the production line is 0.5523 mΩ. The DCR value of the reference battery monomer when assembled into the electric box calculated by substituting it into the fitting relationship between the DCR value and the storage days is 0.59 mΩ. The initial DCR value obtained by testing another battery monomer in this batch on the production line is 0.56 mΩ. Then the DCR value of this battery monomer when assembled into the electric box is 0.59*0.56 / 0.5523 = 0.598 mΩ.

[0112] In this embodiment, by correcting the first DCR value of the obtained battery cell, the first DCR values of other battery cells can be obtained quickly and accurately, reducing the calculation amount and improving the processing efficiency of the control system.

[0113] In some other embodiments, such as Figure 8As shown, S140, that is, performing time correction on the second DC resistance value of each battery cell to obtain the first DC resistance value of each battery cell, includes: S142, substituting the storage time of each battery cell and the second DC resistance value of each battery cell into the second mapping function of the DC resistance value and the storage time to obtain the first DC resistance value of each battery cell.

[0114] For example, according to the following formula, time correction can be performed on the second DCR value of each battery cell to obtain the first DCR value of each battery cell:

[0115] R1 = aD 2 + bD + c + R2 (4).

[0116] Wherein, a, b, and c are constants, R1 is the first DCR value of each battery cell, R2 is the second DCR value of each battery cell, and D is the storage time of each battery cell.

[0117] Using the above formula (4) to obtain the first DCR value of each battery cell is not affected by the time when the battery cell obtains the second DCR value and the time when it is assembled into a battery system. That is, once the second DCR value of the battery cell and its storage time are obtained, substituting them into the above formula (4) can obtain the first DCR value of the battery cell.

[0118] In this embodiment, by directly substituting the second DCR value of the battery cell and the storage time of the battery cell into the relational expression, the first DCR value of the battery cell can be accurately obtained, and it is not affected by other battery cells, and the calculation method is flexible.

[0119] Continue to refer to Figure 6 , the method 100 further includes: S150, performing temperature correction on the second resistance value of the connection component to obtain the first resistance value of the connection component, and the second resistance value of the connection component is the test value of the resistance of the connection component at 25°C.

[0120] Since the resistance value of the connection component is related to temperature, the resistance values of the connection component at different temperatures vary greatly. If the influence of temperature on the resistance value of the connection component is not removed when calculating the DCR value of the battery system, the DCR difference between battery systems cannot be truly reflected. Therefore, it is necessary to correct the resistance value obtained by the connection component at a certain reference temperature to obtain the true resistance value of the connection component at the current ambient temperature. This reference temperature can usually be room temperature, for example, 25°C.

[0121] Similar to time correction, a relationship between resistance and temperature is stored inside the control system. It should be noted that different connection components can correspond to different relationships between resistance and temperature. This relationship can be obtained by the control system acquiring a large number of corresponding resistance-temperature values of the same connection component and performing fitting, thereby obtaining the relationship between resistance and temperature of the connection component. In other embodiments, the control system can also obtain it from another control system, that is to say, the relationship between resistance and temperature is obtained by fitting from another control system.

[0122] In this embodiment, calculating the DCR value of the battery system based on the resistance value of the connection component after temperature correction can provide a more accurate and reliable basis for the subsequent DCR consistency judgment of multiple battery systems.

[0123] In some embodiments, as Figure 9 shown, S150, that is, performing temperature correction on the second resistance value of the connection component to obtain the first resistance value of the connection component. The second resistance value of the connection component is the test value of the resistance of the connection component at 25°C, including: S151, substituting the temperature coefficient of the connection component, the second resistance value of the connection component, and the current ambient temperature into a preset temperature correction function to obtain the first resistance value of the connection component.

[0124] For example, the first resistance value of the connection component can be determined according to the following formula:

[0125] z = R0(1 + αT) (5).

[0126] Among them, α is the temperature coefficient of the connection component, R0 is the test value, and T is the current ambient temperature.

[0127] For example, at room temperature of 25°C, the resistance value R0 of the busbar component in the electrical box is measured actually. The temperature is adjusted to obtain the resistance values RT of the busbar component at different temperatures. The resistance values RT and the temperature T at different temperatures are fitted to obtain the temperature coefficient α of the busbar component. Then, the resistance value of the busbar component at any temperature is obtained as RT = R0(1 + αT), as Figure 10 shown. In a similar manner, the resistance values of other connection components in the electrical box at any temperature can also be obtained. According to the ambient temperature during the assembly of the electrical box production line, substituting it into the resistance relationship formulas of each connection component, the calibrated resistance values of other connection components except the battery cells can be obtained. Finally, when calculating the DCR value of the electrical box, the calibrated resistance values of all these connection components need to be added up to obtain the first resistance value z of the connection components in the electrical box.

[0128] Next, the method 200 for screening electrical boxes provided by the embodiments of the present application will be described in detail in combination with Figure 11 As shown in Figure 11As shown, the method 200 includes:

[0129] S201, loading a battery cell. Specifically, place the battery cell at a designated position on the production line for subsequent assembly.

[0130] S202, tracing the second DC resistance value and the warehousing time of the battery cell.

[0131] S203, calculating the storage time of the battery cell, that is, storage time = current time - warehousing time.

[0132] S204, calculating the first DC resistance value of the battery cell according to the corresponding relationship between the DC resistance value and the storage time.

[0133] S205, calculating the sum x of the first DC resistance values of n battery cells.

[0134] S206, calculating the first resistance value z of the connecting component at the current temperature according to the corresponding relationship between the resistance value and the temperature of the connecting component;

[0135] S207, assembling n battery cells into an electric box and calculating the DC resistance value y of the electric box = x + z.

[0136] S208, calculating the proportion O of the DC resistance values of n battery cells = x / (x + z).

[0137] S209, determining whether O is greater than a preset threshold m.

[0138] S210, when O is greater than m, determining that the assembled electric box is a non - qualified electric box.

[0139] S211, when O is not greater than m, determining that the assembled electric box is a qualified electric box.

[0140] It should be understood that in various embodiments of the present application, the magnitudes of the sequence numbers of the above - mentioned processes do not mean the sequence of execution. The execution sequence of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application. For example, S205 can be executed after S206.

[0141] The method for screening a battery system according to the embodiments of the present application is described in detail above. Next, in combination with Figure 12 The device for screening a battery system according to the embodiments of the present application will be described in detail. The technical features described in the method embodiments are applicable to the following device embodiments.

[0142] Figure 12 A schematic block diagram of the device 300 for screening a battery system according to the embodiments of the present application is shown. The battery system includes a plurality of battery units. As Figure 12As shown, the device 300 includes the following parts or all of the content.

[0143] A determination unit 310, configured to determine a DC resistance value x of a plurality of battery cells according to a first DC resistance value of each battery cell in the plurality of battery cells;

[0144] An acquisition unit 320, configured to acquire a DC resistance value y of the battery system;

[0145] The determination unit 310 is further configured to: determine whether the battery system is a qualified battery system according to the ratio of x to y.

[0146] In a possible embodiment, the battery system further includes a connection component, and the acquisition unit 320 is specifically configured to: determine the sum of the DC resistance value x of the plurality of battery cells and a first resistance value z of the connection component as the DC resistance value y of the battery system.

[0147] In a possible embodiment, the plurality of battery cells include M groups of battery cells connected in series, M is a positive integer greater than 1, and the determination unit 310 is specifically configured to: determine the DC resistance value of each group of battery cells in the M groups of battery cells according to the DC resistance value of each battery cell in the plurality of battery cells; determine the sum of the DC resistance values of each group of battery cells in the M groups of battery cells as the DC resistance value x of the plurality of battery cells.

[0148] In a possible embodiment, the battery system is an electrical box, and the electrical box includes M groups of battery monomers connected in series.

[0149] In a possible embodiment, each group of battery monomers in the M groups of battery monomers includes S battery monomers connected in series, and S is a positive integer.

[0150] In a possible embodiment, each group of battery monomers in the M groups of battery monomers includes N battery monomers connected in parallel, and N is a positive integer greater than 1.

[0151] In a possible embodiment, the battery system is an electrical cabinet, and the electrical cabinet includes M groups of electrical boxes connected in series, and each group of electrical boxes in the M groups of electrical boxes includes T electrical boxes connected in series, and T is a positive integer.

[0152] In a possible embodiment, the acquisition unit 320 is further configured to: perform time correction on the second DC resistance value of each battery cell to obtain the first DC resistance value of each battery cell.

[0153] In a possible embodiment, the obtaining unit 320 is specifically configured to: correct the second DC resistance value of each battery cell according to the ratio between the second DC resistance value and the first DC resistance value of the reference battery cell, so as to obtain the first DC resistance value of each battery cell, where the first DC resistance value of the reference battery cell is obtained by substituting the storage time of the reference battery cell and the second DC resistance value of the reference battery cell into the first mapping function between the DC resistance value and the storage time.

[0154] In a possible embodiment, the obtaining unit 320 is specifically configured to: substitute the storage time of each battery cell and the second DC resistance value of each battery cell into the second mapping function between the DC resistance value and the storage time, and obtain the first DC resistance value of each battery cell.

[0155] In a possible embodiment, the obtaining unit 320 is further configured to: perform temperature correction on the second resistance value of the connection component to obtain the first resistance value of the connection component, where the second resistance value of the connection component is the test value of the resistance of the connection component at 25°C.

[0156] In a possible embodiment, the obtaining unit 320 is specifically configured to: substitute the temperature coefficient of the connection component, the second resistance value of the connection component, and the current ambient temperature into a preset temperature correction function, and obtain the first resistance value of the connection component.

[0157] It should be understood that each of the above modules in the apparatus 300 is used to implement Figures 2 to 11 the corresponding processes in each of the methods in

[0158] Figure 13 FIG. shows a schematic block diagram of a control system 400 for screening a battery system according to an embodiment of the present application. As Figure 13 shown, the control system 400 includes a processor 410 and a memory 420, where the memory 420 is used to store instructions, and the processor 410 is used to read the instructions and execute the methods of various embodiments of the present application based on the instructions.

[0159] Among them, the memory 420 may be an independent device from the processor 410, or may be integrated in the processor 410.

[0160] Optionally, as Figure 13 shown, the control system 400 may further include a transceiver 430, and the processor 410 may control the transceiver 430 to communicate with other devices. Specifically, information or data may be sent to other devices, or information or data sent by other devices may be received.

[0161] It should be understood that the processor in the embodiments of the present application may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method embodiments can be completed by the integrated logic circuit in the hardware of the processor or instructions in the form of software. The above-mentioned processor may be a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It can implement or execute the various methods, steps and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The steps of the method disclosed in combination with the embodiments of the present application can be directly embodied as being executed by the hardware decoding processor, or executed by a combination of the hardware and software modules in the decoding processor. The software module may be located in a mature storage medium in the art such as random access memory, flash memory, read-only memory, programmable read-only memory or electrically erasable programmable memory, register, etc. This storage medium is located in the memory, and the processor reads the information in the memory and combines its hardware to complete the steps of the above method.

[0162] It can be understood that the memory in the embodiments of the present application can be a volatile memory or a non-volatile memory, or can include both volatile and non-volatile memories. Among them, the non-volatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory can be a random access memory (RAM), which is used as an external cache. By way of example but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchlink dynamic random access memory (SLDRAM), and direct rambus random access memory (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to include, but not be limited to, these and any other suitable types of memory.

[0163] The embodiments of the present application further provide a computer-readable storage medium for storing a computer program.

[0164] Optionally, the computer-readable storage medium can be applied to the control system of the screening battery system in the embodiments of the present application, and the computer program causes the computer to execute the corresponding processes implemented by the control system in each of the methods of the embodiments of the present application. For the sake of brevity, they will not be described herein again.

[0165] The embodiments of the present application further provide a computer program product including computer program instructions.

[0166] Optionally, the computer program product can be applied to the control system of the screening battery system in the embodiments of the present application, and the computer program instructions cause the computer to execute the corresponding processes implemented by the control system in each of the methods of the embodiments of the present application. For the sake of brevity, they will not be described herein again.

[0167] The embodiments of the present application further provide a computer program.

[0168] Optionally, the computer program can be applied to the control system for screening battery systems in the embodiments of the present application. When the computer program runs on a computer, it causes the computer to execute the corresponding processes implemented by the control system in each method of the embodiments of the present application. For the sake of brevity, details are not described herein again.

[0169] In several embodiments provided in the present application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed mutual coupling, direct coupling, or communication connection can be through some interfaces. The indirect coupling or communication connection of the devices or units can be in electrical, mechanical, or other forms.

[0170] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0171] In addition, in each embodiment of the present application, the functional units can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit.

[0172] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, ROM, RAM, magnetic disks, or optical discs that can store program codes.

[0173] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present application and should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for screening a battery system, characterized in that, The battery system includes a plurality of battery cells, and the method includes: Determining a DC resistance value x of the plurality of battery cells according to a first DC resistance value of each battery cell in the plurality of battery cells; Obtaining a DC resistance value y of the battery system; Determining whether the battery system is a qualified battery system according to the ratio of x to y.

2. The method according to claim 1, characterized in that The battery system further includes a connection component, and obtaining the DC resistance value y of the battery system includes: Determining the sum of the DC resistance value x of the plurality of battery cells and a first resistance value z of the connection component as the DC resistance value y of the battery system.

3. The method according to claim 1 or 2, characterized in that, The plurality of battery cells include M groups of battery cells connected in series, where M is a positive integer greater than 1. Determining the DC resistance value x of the plurality of battery cells according to the first DC resistance value of each battery cell in the plurality of battery cells includes: Determining a DC resistance value of each group of battery cells in the M groups of battery cells according to the first DC resistance value of each battery cell in the plurality of battery cells; Determining the sum of the DC resistance values of the M groups of battery cells as the DC resistance value x of the plurality of battery cells.

4. The method according to claim 3, characterized in that, The battery system is an electrical box, and the electrical box includes M groups of battery monomers connected in series.

5. The method according to claim 4, wherein Each group of battery monomers in the M groups of battery monomers includes S battery monomers connected in series, where S is a positive integer.

6. The method according to claim 4, wherein Each group of battery monomers in the M groups of battery monomers includes N battery monomers connected in parallel, where N is a positive integer greater than 1.

7. The method according to claim 3, characterized in that, The battery system is an electrical cabinet, and the electrical cabinet includes M groups of electrical boxes connected in series. Each group of electrical boxes in the M groups of electrical boxes includes T electrical boxes connected in series, where T is a positive integer.

8. The method according to any one of claims 1 to 7, characterized in that, The method further includes: Performing time correction on a second DC resistance value of each battery cell to obtain the first DC resistance value of each battery cell.

9. The method according to claim 8, characterized in that, Performing time correction on the second DC resistance value of each battery cell to obtain the first DC resistance value of each battery cell includes: Correcting the second DC resistance value of each battery cell according to the ratio between the second DC resistance value of a reference battery cell and the first DC resistance value of the reference battery cell to obtain the first DC resistance value of each battery cell. The first DC resistance value of the reference battery cell is obtained by substituting the storage time of the reference battery cell and the second DC resistance value of the reference battery cell into a first mapping function between the DC resistance value and the storage time.

10. The method according to claim 8, wherein Performing time correction on the second DC resistance value of each battery cell to obtain the first DC resistance value of each battery cell includes: Substituting the storage time of each battery cell and the second DC resistance value of each battery cell into a second mapping function between the DC resistance value and the storage time to obtain the first DC resistance value of each battery cell.

11. The method according to claim 2, characterized in that, The method further includes: Performing temperature correction on a second resistance value of the connection component to obtain the first resistance value of the connection component. The second resistance value of the connection component is a test value of the resistance of the connection component at 25°C.

12. The method according to claim 11, wherein Performing temperature correction on the second resistance value of the connection component to obtain the first resistance value of the connection component includes: Substituting the temperature coefficient of the connection component, the second resistance value of the connection component, and the current ambient temperature into a preset temperature correction function to obtain the first resistance value of the connection component.

13. An apparatus for screening a battery system, characterized in that, The battery system includes a plurality of battery cells, and the device includes: A determination unit configured to determine the DC resistance value x of the plurality of battery cells according to the first DC resistance value of each battery cell in the plurality of battery cells; An acquisition unit configured to acquire the DC resistance value y of the battery system; The determination unit is further configured to: Determine whether the battery system is a qualified battery system according to the ratio of x to y.

14. The device according to claim 13, characterized in that, The battery system further includes a connection component, and the acquisition unit is specifically configured to: Determine the sum of the DC resistance value x of the plurality of battery cells and the first resistance value z of the connection component as the DC resistance value y of the battery system.

15. The device according to claim 13 or 14, characterized in that The plurality of battery cells include M groups of battery cells connected in series, where M is a positive integer greater than 1, and the determination unit is specifically configured to: Determine the DC resistance value of each group of battery cells in the M groups of battery cells according to the DC resistance value of each battery cell in the plurality of battery cells; Determine the sum of the DC resistance values of each group of battery cells in the M groups of battery cells as the DC resistance value x of the plurality of battery cells.

16. The device according to claim 15, characterized in that, The battery system is an electric box, and the electric box includes M groups of battery monomers connected in series.

17. The device according to claim 16, characterized in that, Each group of battery monomers in the M groups of battery monomers includes S battery monomers connected in series, where S is a positive integer.

18. The device according to claim 16, wherein, Each group of battery monomers in the M groups of battery monomers includes N battery monomers connected in parallel, where N is a positive integer greater than 1.

19. The device according to claim 15, characterized in that, The battery system is an electric cabinet, and the electric cabinet includes M groups of electric boxes connected in series. Each group of electric boxes in the M groups of electric boxes includes T electric boxes connected in series, where T is a positive integer.

20. The device according to any one of claims 13 to 19, characterized in that, The acquisition unit is further configured to: Perform time correction on the second DC resistance value of each battery cell to obtain the first DC resistance value of each battery cell.

21. The device according to claim 20, characterized in that, The acquisition unit is specifically configured to: Correct the second DC resistance value of each battery cell according to the ratio between the second DC resistance value and the first DC resistance value of the reference battery cell to obtain the first DC resistance value of each battery cell. The first DC resistance value of the reference battery cell is obtained by substituting the storage time of the reference battery cell and the second DC resistance value of the reference battery cell into a first mapping function between the DC resistance value and the storage time.

22. The device according to claim 20, wherein, The acquisition unit is specifically configured to: Substitute the storage time of each battery cell and the second DC resistance value of each battery cell into a second mapping function between the DC resistance value and the storage time to obtain the first DC resistance value of each battery cell.

23. The device according to claim 14, characterized in that, The acquisition unit is further configured to: Perform temperature correction on the second resistance value of the connection component to obtain the first resistance value of the connection component, where the second resistance value of the connection component is the test value of the resistance of the connection component at 25°C.

24. The device according to claim 23, characterized in that, The obtaining unit is specifically configured to: Substitute the temperature coefficient of the connection component, the second resistance value of the connection component, and the current ambient temperature into a preset temperature correction function to obtain the first resistance value of the connection component.

25. A control system for screening a battery system, characterized in that, Comprising: A memory for storing instructions; A processor for reading the instructions and executing the method according to any one of claims 1 to 12 based on the instructions.

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