Detection method and detection device of DCR and energy storage system

Abstract

The invention provides a DCR detection method and device and an energy storage system, and can effectively detect the DCR of a battery pack, and the detection method comprises the steps: obtaining the open-circuit voltage of the battery pack; and determining the DCR of the battery pack according to the OCV of the battery pack, the voltage of the battery pack and the current of the battery pack. Since the DCR of the battery pack is determined by using the dynamic voltage and current of the battery pack and the static OCV of the battery pack, the method does not depend on the initial voltage of the battery pack, and the detection result of the DCR is not influenced by the instability of the initial voltage, so that the accuracy is higher, and the DCR can be dynamically tested, thereby quickly and accurately obtaining the DCR of the battery pack.

Description

Technical Field

[0001] This application relates to the field of batteries, and particularly to a method and device for detecting direct current resistance (DCR) and an energy storage system. Background Art

[0002] Energy storage systems usually have requirements such as high voltage and large capacity. Therefore, a large number of batteries are required in the energy storage system to be connected in series and parallel to form products such as electric cabinets or containers, and energy interaction with the power grid is carried out through a power conversion system (PCS). The battery packs in the energy storage system can be connected in parallel. In the case of poor consistency among multiple battery packs, the DCR difference between the battery packs will cause a current difference between the battery packs, resulting in uneven current distribution between the battery packs. On the one hand, the problem of uneven current distribution will cause the entire energy storage system to cut off charge and discharge prematurely, affecting the capacity and power of the entire energy storage system; on the other hand, the battery pack with too large current may exceed the charging capacity window of the battery cell, affecting the safety performance and service life of the battery cell. Therefore, how to effectively detect the DCR of the battery has become an urgent problem to be solved. Summary of the Invention

[0003] Embodiments of this application provide a method and device for detecting DCR and an energy storage system, which can effectively detect the DCR of the battery.

[0004] In a first aspect, a method for detecting DCR is provided. The detection method includes: obtaining the OCV of the battery pack; determining the DCR of the battery pack according to the OCV of the battery pack, the voltage of the battery pack, and the current of the battery pack.

[0005] In the embodiments of this application, the detection of the DCR of the battery pack is realized through the information of the current OCV, voltage, and current of the battery pack. Since this DCR detection method utilizes the current voltage and current of the battery pack and the current static OCV of the battery pack, it does not depend on the initial voltage of the battery pack and will not affect the DCR detection result due to the instability of the initial voltage. Therefore, it has high accuracy and can perform dynamic testing on the DCR, so as to quickly and accurately obtain the DCR of the battery pack.

[0006] In some possible implementation manners, obtaining the OCV of the battery pack includes: obtaining the SOC of the battery pack; determining the OCV of the battery pack according to the SOC of the battery pack and the corresponding relationship between the preset OCV and SOC.

[0007] In this implementation manner, the relationship curve between the OCV and the SOC of the battery pack can be pre-built in the BMS software to facilitate obtaining the current OCV of the battery pack. When detecting the DCR of the battery pack, the OCV corresponding to the SOC can be determined according to the current SOC of the battery pack and this relationship curve between the OCV and the SOC, and this OCV can be used as the current OCV of the battery pack to calculate the DCR of the battery pack.

[0008] In some possible implementation manners, determining the DCR of the battery pack according to the OCV of the battery pack, the voltage of the battery pack, and the current of the battery pack includes: determining the voltage difference between the voltage of the battery pack and the OCV of the battery pack; determining the ratio between the voltage difference and the current of the battery pack; and determining the ratio as the DCR of the battery pack.

[0009] In this implementation manner, the current voltage of the battery pack can be subtracted from the OCV of the battery pack, and the ratio between the difference and the current of the battery pack can be calculated, so as to use this ratio as the current DCR of the battery pack. Since this calculation method of DCR only uses the current voltage and current of the battery pack and the current static OCV of the battery pack, and it does not depend on the initial voltage of the battery pack, it has high accuracy and can perform dynamic testing on DCR.

[0010] In some possible implementation manners, the detection method further includes: determining whether there is uneven current sharing among the multiple battery packs according to the DCRs of the multiple parallel-connected battery packs.

[0011] In this implementation manner, when multiple battery packs are connected in parallel to the power grid, since the voltages of the multiple battery packs are the same, based on Ohm's law, the DCR differences among the multiple battery packs will cause current differences among the battery packs, resulting in uneven current sharing among the multiple battery packs and affecting the capacity and power of the battery cluster. Therefore, it is possible to determine whether there is uneven current sharing among the multiple battery packs by detecting the differences among the DCRs of the multiple parallel-connected battery packs, so as to timely discover and prevent uneven current sharing among the parallel-connected battery packs.

[0012] For example, determining whether there is uneven current sharing among the multiple battery packs according to the DCRs of the multiple parallel-connected battery packs includes: determining that there is uneven current sharing among the multiple battery packs when the ratio between the DCR of the first battery pack and the DCR of the second battery pack among the multiple battery packs is greater than a preset DCR threshold, where the first battery pack is the battery pack with the largest DCR among the multiple battery packs, and the second battery pack is the battery pack with the smallest DCR among the multiple battery packs.

[0013] In this way, according to the DCR difference between the battery pack with the largest DCR and the battery pack with the smallest DCR among multiple parallel-connected battery packs, the uneven current distribution among the multiple battery packs can be detected in a timely manner.

[0014] In some possible implementation manners, the battery pack is a battery cluster or an electric cabinet, the battery cluster or the electric cabinet includes a plurality of electric boxes connected in series and / or in parallel, and each electric box includes a plurality of battery cells connected in series and / or in parallel.

[0015] The above-mentioned battery pack can be a battery cluster or an electric cabinet. The battery cluster or the electric cabinet includes a plurality of electric boxes connected in series and / or in parallel, and each electric box includes a plurality of battery cells connected in series and / or in parallel. Uneven current distribution may occur between other parallel units in the energy storage system, and the DCRs of these parallel units can also be determined by the DCR detection method of the embodiments of the present application, so as to detect and prevent the uneven current distribution between these parallel units in a timely manner.

[0016] In a second aspect, a DCR detection device is provided. The detection device includes: an acquisition module configured to obtain the OCV of a battery pack; a processing module configured to determine the DCR of the battery pack according to the OCV of the battery pack, the voltage of the battery pack, and the current of the battery pack.

[0017] In some possible implementation manners, the acquisition module is specifically configured to obtain the SOC of the battery pack; and determine the OCV of the battery pack according to the SOC of the battery pack and the corresponding relationship between the preset OCV and SOC.

[0018] In some possible implementation manners, the processing module is specifically configured to determine the voltage difference between the voltage of the battery pack and the OCV of the battery pack; determine the ratio of the voltage difference to the current of the battery pack; and determine the ratio as the DCR of the battery pack.

[0019] In some possible implementation manners, the processing module is further configured to determine whether there is uneven current distribution among the multiple parallel-connected battery packs according to the DCRs of the multiple battery packs.

[0020] In some possible implementation manners, the processing module is specifically configured to determine that there is uneven current distribution among the multiple battery packs when the ratio between the DCR of the first battery pack and the DCR of the second battery pack among the multiple battery packs is greater than a preset DCR threshold, where the first battery pack is the battery pack with the largest DCR among the multiple battery packs, and the second battery pack is the battery pack with the smallest DCR among the multiple battery packs.

[0021] In some possible implementations, the battery pack is a battery cluster or an electrical cabinet, the battery cluster or the electrical cabinet includes a plurality of electrical boxes connected in series and / or in parallel, and each electrical box includes a plurality of battery cells connected in series and / or in parallel.

[0022] In a third aspect, a energy storage system is provided, including: a plurality of battery packs connected in parallel; and the DCR detection device described in the second aspect or any possible implementation of the second aspect, where the detection device is configured to detect the DCR of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] To more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required to be used 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, other drawings can be obtained based on the drawings without creative efforts.

[0024] Figure 1 It is a schematic diagram of a possible energy storage system according to an embodiment of the present application.

[0025] Figure 2 It is a schematic diagram of a possible battery cluster according to an embodiment of the present application.

[0026] Figure 3 It is a schematic diagram of a possible electrical box according to an embodiment of the present application.

[0027] Figure 4 It is a schematic flowchart of the DCR detection method according to an embodiment of the present application.

[0028] Figure 5 It is a schematic diagram of the OCV-SOC curve of the battery pack.

[0029] Figure 6 It is a schematic flowchart of obtaining the OCV according to an embodiment of the present application.

[0030] Figure 7 It is a schematic flowchart of calculating the DCR according to an embodiment of the present application.

[0031] Figure 8 is Figure 4 a flowchart of a possible implementation of the DCR detection method shown.

[0032] Figure 9 It is a schematic block diagram of the DCR detection device according to an embodiment of the present application.

[0033] Figure 10 It is a schematic block diagram of the DCR detection equipment according to an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The embodiments of the present application will be further described in detail below in conjunction with the accompanying drawings and examples. The following detailed description of the examples and the accompanying drawings are used to exemplarily illustrate the principles 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.

[0035] Since energy storage systems usually have requirements such as high voltage and large capacity, a large number of batteries are required in the energy storage system to be connected in series and parallel to form products such as electrical cabinets or containers, and energy interaction is carried out with the power grid through the PCS. Among them, the PCS is used to realize the conversion between the alternating current signal of the power grid and the direct current signal of the energy storage system.

[0036] As an example, as Figure 1 shown, the energy storage system 1 includes N battery clusters, namely battery clusters R1 to battery cluster R N , where N is a positive integer. The battery clusters R1 to battery cluster R N are connected in parallel with each other, and charging or discharging is carried out with the power grid through the PCS. Among them, each battery cluster includes a plurality of electrical boxes. For example, as Figure 2 shown, each of the battery clusters R1 to battery cluster R N includes M electrical boxes, namely electrical boxes B1 to electrical box B M , where M is a positive integer. The M electrical boxes are connected in series; or, several of the M electrical boxes are first connected in parallel to form a parallel unit, and then multiple parallel units are connected in series to form a battery cluster. Among them, each electrical box is assembled by K battery cells. For example, as Figure 3 shown, each of the electrical boxes B1 to electrical box B M includes K battery cells connected in series and / or in parallel, namely battery cells C1 to battery cell C [[ID=)23]] K .

[0037] In the case where the consistency between multiple battery clusters in the energy storage system is poor, the DCR difference between the battery clusters may cause a current difference between the battery clusters, resulting in uneven current distribution between the battery clusters, which affects the capacity and power of the entire energy storage system. Therefore, it is necessary to detect the DCR of the battery clusters.

[0038] Generally, the DCR of the battery cluster can be calculated by using the ratio of the voltage change amount of the battery cluster within a predetermined time period to the current. Among them, the voltage change amount is the voltage difference between the starting voltage of the battery cluster at the start of the test and the voltage reached by the battery cluster after the predetermined time period. Since the initial voltage of the battery cluster needs to be used, it is required that the battery cluster has a stable initial voltage during the test process. However, in actual operating conditions, it is difficult to ensure the stability of the initial voltage of the battery cluster, which will therefore affect the test results of the DCR.

[0039] To this end, the present application provides a DCR detection solution, which realizes the detection of the DCR of the battery pack through the information of the current OCV, voltage and current of the battery pack. The test process does not depend on the initial voltage of the battery pack and will not affect the DCR detection result due to the instability of the initial voltage. It has high accuracy and can perform dynamic testing on the DCR, so as to quickly and accurately obtain the DCR of the battery pack.

[0040] Figure 4 FIG. shows the DCR detection method according to an embodiment of the present application. This method can be executed by a battery management system (BMS), such as including a master battery management unit (MBMU) and / or a sub-battery management unit (SBMU). As Figure 4 shown, the DCR detection method 100 according to an embodiment of the present application includes some or all of the following steps.

[0041] In step 110, obtain the open circuit voltage (OCV) of the battery pack.

[0042] In step 120, determine the DCR of the battery pack according to the OCV of the battery pack, the voltage of the battery pack, and the current of the battery pack.

[0043] Here, the battery pack can be, for example, a battery cluster or an electric cabinet. Among them, the battery cluster or the electric cabinet includes a plurality of electric boxes connected in series and / or in parallel, and each electric box includes a plurality of battery cells connected in series and / or in parallel. Among them, the electric cabinet can be regarded as a battery product formed by the battery cluster. Therefore, the battery cluster in the embodiment of the present application can also be replaced by the electric cabinet. A plurality of electric cabinets can be assembled to form a container. The following takes the battery cluster shown in Figures 1 to 3 as an example to describe in detail the DCR detection method 100 according to an embodiment of the present application. Of course, in addition to the possible uneven current sharing between multiple parallel-connected battery clusters, there may also be uneven current sharing between other units that need to be connected in parallel in the energy storage system. The DCR of these parallel-connected units can also be determined by method 100 to facilitate the timely discovery and prevention of uneven current sharing between these parallel-connected units.

[0044] The OCV of the battery pack refers to the terminal voltage of the battery pack in the open circuit state, which is a physical quantity of the battery under static conditions and can be regarded as the static voltage of the battery pack.

[0045] The voltage and current of the battery pack refer to the voltage and current of the battery pack under actual working conditions, and the working conditions include charging or discharging of the battery pack.

[0046] In the embodiment of the present application, the DCR of the battery pack is obtained by using the current OCV, voltage and current information of the battery pack. This method does not depend on the initial voltage of the battery pack and will not affect the detection result of the DCR due to the instability of the initial voltage. Therefore, it has high accuracy and can perform dynamic testing on the DCR, thereby quickly and accurately obtaining the DCR of the battery pack.

[0047] In some embodiments, as Figure 5 As shown, step 110 may include step 111 and step 112 .

[0048] In step 111 , the state of charge (SOC) of the battery pack is obtained.

[0049] In step 112 , the OCV of the battery pack is determined according to the SOC of the battery pack and a preset correspondence between the OCV and the SOC.

[0050] For example, the OCV corresponding to the SOC of the battery pack is determined as the OCV of the battery pack, and is used to determine the DCR of the battery pack in the subsequent step 120 .

[0051] The correspondence between OCV and SOC can be realized in various forms. For example, the correspondence between OCV and SOC can be a table of mapping relationships between multiple OCV values and multiple SOC values; it can also be a curve or formula used to represent the correspondence between OCV and SOC; or other forms that can represent the correspondence between OCV and SOC of the battery pack.

[0052] As an example, Figure 6 The OCV-SOC curve of the battery shown in FIG. 1 shows the corresponding relationship between the SOC and OCV of the battery. Figure 6 As shown, during the charge and discharge process of the battery, as the chemical reaction inside the battery continues, the OCV of the battery will also change. Optionally, under the operating conditions of the battery, the SOC of the battery can be adjusted at certain intervals and the battery voltage can be collected after it is left to stand for a certain period of time to eliminate polarization. For example, a suitable battery cell can be selected and charged with a current of 0.05C. After each charge of 5% SOC, the battery cell is left to stand for 2 hours or 3 hours to eliminate polarization, and the voltage of the battery cell is collected after standing still, thereby obtaining multiple sets of corresponding SOC and OCV. By fitting the data of multiple sets of corresponding SOC and OCV, an OCV-SOC curve can be drawn, also known as a static OCV curve; similarly, during the discharge process, the corresponding OCV-SOC curve can also be obtained in the above manner.

[0053] The OCV-SOC curve of the battery pack can be pre-built into the software of the BMS to facilitate obtaining the current OCV of the battery pack. When detecting the current DCR of the battery pack, the OCV corresponding to the current SOC of the battery pack can be determined according to the current SOC of the battery pack and the OCV-SOC curve, and this OCV can be used as the current OCV of the battery pack to calculate the DCR of the battery pack.

[0054] In some embodiments, as Figure 7 shown, step 120 may include step 121, step 122, and step 123.

[0055] In step 121, determine the voltage difference between the voltage of the battery pack and the OCV of the battery pack.

[0056] In step 122, determine the ratio of the voltage difference to the current of the battery pack.

[0057] In step 123, the ratio between the voltage difference and the current of the battery pack is determined as the DCR of the battery pack.

[0058] According to the electrochemical polarization principle of the battery, during the charge and discharge process of the battery pack, the dynamic voltage U of the battery is equal to the sum of the product of the real-time current I of the battery system and the dynamic polarization internal resistance R of the battery pack and the static OCV of the battery pack, that is, U = OCV + I*R.

[0059] Based on this, it can be obtained that R = (U - OCV) / I. Therefore, the DCR of the battery pack can be calculated by using the static voltage of the battery pack and the information of the voltage and current collected in real time.

[0060] Among them, the DCR of the battery pack = (U - OCV) / I, where U is the current voltage value of the battery pack, I is the current current value of the battery pack, and OCV is the value of the static OCV corresponding to this SOC captured from the OCV-SOC curve according to the current SOC of the battery pack.

[0061] It can be seen that by taking the difference between the current voltage of the battery pack and the OCV and calculating the ratio between this difference and the current of the battery pack, and thus taking this ratio as the current DCR of the battery pack, this calculation method of DCR only uses the information of the voltage and current collected currently of the battery pack and the static OCV corresponding to the current SOC of the battery pack, and it does not depend on the initial voltage of the battery pack. Therefore, it has high accuracy and can perform dynamic testing on DCR.

[0062] When multiple battery packs are connected in parallel to the power grid, since the voltages of multiple battery packs are the same, based on Ohm's law, the DCR differences between multiple battery packs will cause current differences between the battery packs, resulting in uneven current distribution among multiple battery packs, which affects the capacity and power of the entire battery system. Therefore, in some embodiments, the detection method 100 may further include: determining whether there is uneven current distribution among multiple battery packs according to the DCRs of the multiple battery packs connected in parallel. That is to say, by detecting the DCRs of the multiple battery packs connected in parallel, it is determined whether there is uneven current distribution among the multiple battery packs, so as to timely detect and prevent uneven current distribution between the parallel battery packs.

[0063] Optionally, it is possible to determine whether there is uneven current distribution among multiple battery packs according to the differences between the DCRs of the multiple battery packs connected in parallel. For example, according to the difference between the DCR of the first battery pack and the DCR of the second battery pack among multiple battery packs, where the first battery pack is the battery pack with the largest DCR among multiple battery packs, and the second battery pack is the battery pack with the smallest DCR among multiple battery packs.

[0064] For example, it can be determined that there is uneven current distribution among multiple battery packs when the ratio between the DCR of the first battery pack and the DCR of the second battery pack among multiple battery packs is greater than the corresponding DCR threshold; or for another example, it can be determined that there is uneven current distribution among multiple battery packs when the difference between the DCR of the first battery pack and the DCR of the second battery pack is greater than the corresponding DCR threshold.

[0065] In this way, according to the DCR difference between the battery pack with the largest DCR and the battery pack with the smallest DCR among multiple battery packs, it is possible to timely detect the uneven current distribution among multiple battery packs.

[0066] As an example, as Figure 8 shown in the DCR detection process, taking the battery pack as a battery cluster as an example, where the SBMU of each battery cluster is responsible for the management of the corresponding battery cluster and uploads relevant data to the MBMU. The MBMU is responsible for the operation management of the entire system formed by multiple battery clusters and can interact with external devices.

[0067] As Figure 8 shown, in step 101, it is determined that the battery cluster is in an operating condition, that is, the battery cluster is currently charging or discharging.

[0068] In step 102, the voltage U and current I of the battery cluster are collected.

[0069] In step 103, the SBMU calculates the SOC of the battery cluster according to the current I.

[0070] For example, the SOC of a battery cluster can be calculated based on the current, charge and discharge time, and charge and discharge direction of the battery cluster. For example, the SOC of the battery cluster = I * T / Q, where T is the charging time and Q is the capacity of the battery cluster, such as the rated capacity or the maximum capacity.

[0071] In step 104, the SBMU grabs the corresponding OCV from the OCV-SOC curve according to the SOC of the battery cluster.

[0072] In step 105, the SBMU calculates the DCR of the battery cluster = (U - OCV) / I according to the OCV, voltage U, and current I of the battery cluster.

[0073] Among them, the SBMU can report the DCR of the corresponding battery cluster to the MBMU.

[0074] In step 106, the MBMU calculates the internal resistance difference between clusters according to the DCR of multiple parallel-connected battery clusters.

[0075] For example, the internal resistance difference can be represented by DCRmax / DCRmin, where DCRmax and DCRmin respectively represent the largest DCR and the smallest DCR among the DCRs of multiple battery clusters.

[0076] In step 107, the MBMU determines whether the internal resistance difference DCRmax / DCRmin between clusters is greater than a preset DCR threshold x%.

[0077] When the internal resistance difference DCRmax / DCRmin between clusters is greater than the DCR threshold x%, that is, when DCRmax / DCRmin > x%, step 108 is executed; when the internal resistance difference DCRmax / DCRmin between clusters is less than or equal to the DCR threshold x%, that is, when DCRmax / DCRmin ≤ x%, the DCR of the battery cluster is continuously detected.

[0078] In step 108, an uneven current sharing strategy is executed.

[0079] The uneven current sharing strategy can be built into the BMS software, for example, to reduce the degree of uneven current sharing between multiple parallel-connected battery clusters. For example, the current of some battery clusters or all battery clusters can be reduced based on a certain strategy.

[0080] The above has described in detail the DCR detection method of the embodiments of the present application. Below, in combination with Figure 9 and Figure 10 The DCR detection device of the embodiments of the present application is described in detail. The technical features described in the method embodiments are applicable to the following device embodiments.

[0081] The embodiments of the present application also provide a DCR detection device 200. AsFigure 9 As shown in Figure 9 , the detection device 200 includes an acquisition module 210 and a processing module 220. Among them, the acquisition module 210 is used to obtain the open-circuit voltage of the battery pack. The processing module 220 is used to determine the DCR of the battery pack according to the OCV of the battery pack, the voltage of the battery pack, and the current of the battery pack.

[0082] The battery pack may include, for example, battery clusters, which include a plurality of battery boxes connected in series and / or in parallel, and each battery box includes a plurality of battery cells connected in series and / or in parallel.

[0083] In some embodiments, the acquisition module 210 is specifically configured to obtain the state of charge SOC of the battery pack; and determine the OCV corresponding to the SOC of the battery pack as the OCV of the battery pack according to the SOC of the battery pack and the corresponding relationship between the preset OCV and SOC.

[0084] In some embodiments, the processing module 220 is specifically configured to determine the voltage difference between the voltage of the battery pack and the OCV of the battery pack; determine the ratio between the voltage difference and the current of the battery pack; and determine this ratio as the DCR of the battery pack.

[0085] In some embodiments, the processing module 220 is further configured to determine whether there is uneven current sharing among multiple battery packs according to the DCRs of the multiple parallel-connected battery packs.

[0086] In some embodiments, the processing module 220 is specifically configured to determine that there is uneven current sharing among multiple battery packs when the ratio between the DCR of the first battery pack and the DCR of the second battery pack among the multiple battery packs is greater than a preset DCR threshold, where the first battery pack is the battery pack with the largest DCR among the multiple battery packs, and the second battery pack is the battery pack with the smallest DCR among the multiple battery packs.

[0087] It should be understood that the specific manner of DCR detection performed by the detection device 200 and the beneficial effects produced can be referred to the relevant descriptions in the method embodiments. For simplicity, they will not be elaborated here.

[0088] This application also provides an energy storage system, such as Figure 1 the energy storage system 1 described above. The energy storage system includes a plurality of parallel-connected battery packs and the DCR detection device 200 described in any of the above embodiments. The detection device 200 is used to detect the DCR of the battery pack.

[0089] This application also provides a computer-readable storage medium for storing a computer program, which, when executed by a computing device, enables the computing device to implement the DCR detection method 100 described in any of the above embodiments. Optionally, the computer program may be the computer program in the BMS.

[0090] The present application also provides a schematic block diagram of a DCR detection device 300. The detection device 300 can be, for example, a BMS, such as including an SBMU and / or an MBMU. As Figure 10 shown, the detection device 300 includes a processor 310 and a memory 320. Among them, the memory 320 is used to store instructions, and the processor 310 is used to read the instructions and execute the method 100 of various embodiments of the present application based on the instructions. Among them, the memory 320 can be a separate device independent of the processor 310, or can be integrated in the processor 310.

[0091] Optionally, as Figure 10 shown, the detection device 300 may further include a transceiver 330, and the processor 310 can control the transceiver 330 to communicate with other devices. For example, it can send information or data to other devices, or receive information or data sent by other devices.

[0092] It should be understood that the processor in the embodiments of the present application may be an integrated circuit chip with the ability to process signals. 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 the instructions in the form of software. The above-mentioned processor can 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 can be a microprocessor or 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 the combination of the hardware and software modules in the decoding processor. The software module can be located in a mature storage medium in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a 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.

[0093] 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 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 in the present application is intended to include but not limited to these and any other suitable types of memory.

[0094] It should be noted that on the premise of no conflict, the various embodiments described in the present application and / or the technical features in each embodiment can be combined with each other arbitrarily, and the technical solutions obtained after the combination should also fall within the protection scope of the present application.

[0095] In the embodiments of the present application, the magnitudes of the serial numbers of the respective steps do not indicate the order of execution, and the order of execution of the respective steps should be determined by their functions and internal logics, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0096] Those of ordinary skill in the art can realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or by a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. A professional person can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present application.

[0097] In several embodiments provided by 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 couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of the devices or units can be in electrical, mechanical, or other forms.

[0098] 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 may 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 the embodiments of the present application.

[0099] Although the present application has been described with reference to the preferred embodiments, various improvements can be made to it and components therein can be replaced with equivalents without departing from the scope of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for detecting a DC resistance, characterized in that, The detection method includes: Obtaining the open-circuit voltage of the battery pack; Determining the DC resistance of the battery pack according to the open-circuit voltage of the battery pack, the voltage of the battery pack, and the current of the battery pack.

2. The detection method according to claim 1, wherein The obtaining of the open-circuit voltage of the battery pack includes: Obtaining the state of charge of the battery pack; Determining the open-circuit voltage of the battery pack according to the state of charge of the battery pack and the corresponding relationship between the preset open-circuit voltage and the state of charge.

3. The detection method according to claim 1 or 2, characterized in that The determining of the DC resistance of the battery pack according to the open-circuit voltage of the battery pack, the voltage of the battery pack, and the current of the battery pack includes: Determining the voltage difference between the voltage of the battery pack and the open-circuit voltage of the battery pack; Determining the ratio between the voltage difference and the current of the battery pack; Determining the ratio as the DC resistance of the battery pack.

4. The detection method according to any one of claims 1 to 3, characterized in that, The detection method further includes: Determining whether there is uneven current sharing among the multiple battery packs connected in parallel according to the DC resistances of the multiple battery packs.

5. The detection method according to claim 4, wherein The determining of whether there is uneven current sharing among the multiple battery packs connected in parallel according to the DC resistances of the multiple battery packs includes: When the ratio between the DC resistance of the first battery pack and the DC resistance of the second battery pack among the multiple battery packs is greater than the preset DC resistance threshold, determining that there is uneven current sharing among the multiple battery packs, where the first battery pack is the battery pack with the largest DC resistance among the multiple battery packs, and the second battery pack is the battery pack with the smallest DC resistance among the multiple battery packs.

6. The detection method according to any one of claims 1 to 5, characterized in that, The battery pack is a battery cluster or an electrical cabinet, and the battery cluster or the electrical cabinet includes multiple electrical boxes connected in series and / or in parallel, and each electrical box includes multiple battery cells connected in series and / or in parallel.

7. A detection device for direct current resistance, characterized in that, The detection device includes: An acquisition module for obtaining the open-circuit voltage of the battery pack; A processing module for determining the DC resistance of the battery pack according to the open-circuit voltage of the battery pack, the voltage of the battery pack, and the current of the battery pack.

8. The detection device according to claim 7, wherein, The acquisition module is specifically configured to, Obtain the state of charge of the battery pack; Determine the open-circuit voltage of the battery pack according to the state of charge of the battery pack and the corresponding relationship between the preset open-circuit voltage and the state of charge.

9. The detection device according to claim 7 or 8, characterized in that, The processing module is specifically configured to, Determine the voltage difference between the voltage of the battery pack and the open-circuit voltage of the battery pack; Determine the ratio between the voltage difference and the current of the battery pack; Determine the ratio as the DC resistance of the battery pack.

10. The detection device according to any one of claims 7 to 9, characterized in that, The processing module is further configured to, Determine whether there is uneven current sharing among the multiple battery packs connected in parallel according to the DC resistances of the multiple battery packs.

11. The detection device according to claim 10, wherein The processing module is specifically configured to, When the ratio between the DC resistance of the first battery pack and the DC resistance of the second battery pack among the multiple battery packs is greater than the preset DC resistance threshold, determine that there is uneven current sharing among the multiple battery packs, where the first battery pack is the battery pack with the largest DC resistance among the multiple battery packs, and the second battery pack is the battery pack with the smallest DC resistance among the multiple battery packs.

12. The detection device according to any one of claims 7 to 11, characterized in that, The battery pack is a battery cluster or an electrical cabinet, and the battery cluster or the electrical cabinet includes multiple electrical boxes connected in series and / or in parallel, and each electrical box includes multiple battery cells connected in series and / or in parallel.

13. An energy storage system, characterized in that, Including: A plurality of battery packs connected in parallel; And, A detection device for the DC resistance according to any one of claims 7 to 12, the detection device being used to detect the DC resistance of the battery pack.

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