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, the DCR of a battery pack can be effectively detected, the detection method comprises the steps that a state parameter set of the battery pack at a target moment after the current moment is acquired, and the state parameter set comprises at least one state parameter of the battery pack; and determining the DCR of the battery pack at the target moment according to the state parameter group of the battery pack at the target moment and a preset corresponding relationship between a plurality of state parameter groups and a plurality of DCRs. By establishing the DCR database including the corresponding relation between the state parameter set of the battery pack and the DCR, the DCR database can be used for predicting the DCR of the battery pack under the future working condition under the condition that the state parameters of the battery pack under the future working condition are known.

Description

Technical Field

[0001] The present 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 between 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 the present 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 a set of state parameters of a battery pack at a target time after the current time, where the set of state parameters includes at least one state parameter of the battery pack; and determining the DCR of the battery pack at the target time according to the set of state parameters of the battery pack at the target time and a corresponding relationship between a preset plurality of sets of state parameters and a plurality of DCRs.

[0005] In an embodiment of the present application, by establishing a DCR database including a corresponding relationship between a set of state parameters of a battery pack and DCR, where the set of state parameters includes various state parameters that may affect the DCR of the battery pack, when the state parameters of the battery pack under future working conditions are known, the DCR of the battery pack under future working conditions can be predicted using the DCR database, and risk prediction can be performed based on the DCR. For example, it can be determined in advance whether uneven current distribution may occur between battery packs, and appropriate strategies can be determined and responses can be made in a timely manner, thereby reducing the risk caused by too large a DCR difference between battery packs.

[0006] Wherein, the state parameter group includes at least one of the following state parameters: the SOC of the battery pack, the temperature of the battery pack, the current of the battery pack, the charge and discharge direction of the battery pack, the charge and discharge time of the battery pack, and the SOH of the battery pack.

[0007] For example, the state parameter group includes various state parameters such as SOC, SOH, temperature, charge and discharge direction, charge and discharge time, and charge and discharge current that can affect the DCR of the battery pack, comprehensively considering the influence of different influencing factors on the DCR of the battery pack.

[0008] In some possible implementation manners, determining the DCR of the battery pack at the target moment according to the state parameter group of the battery pack at the target moment and the corresponding relationship between a plurality of preset state parameter groups and a plurality of DCRs includes: determining the DCR corresponding to the state parameter group of the battery pack at the target moment among the plurality of DCRs as the DCR of the battery pack at the target moment.

[0009] In this implementation manner, according to the corresponding relationship between the plurality of state parameter groups and the plurality of DCRs, the DCR corresponding to the state parameter group of the battery pack at the target moment can be selected from the plurality of state parameter groups as the DCR of the battery pack at the target moment, so as to simply and quickly obtain the DCR of the battery pack at the target moment.

[0010] In some possible implementation manners, the state parameter group includes a first state parameter, and the corresponding relationship includes a plurality of values of the first state parameter corresponding to the plurality of DCRs. Determining the DCR of the battery pack at the target moment according to the state parameter group of the battery pack at the target moment and the corresponding relationship between a plurality of preset state parameter groups and a plurality of DCRs includes: determining, among the plurality of values, the first value and the second value that are closest to the parameter value of the first state parameter of the battery pack at the target moment; determining the DCR corresponding to the first value and the DCR corresponding to the second value according to the first value, the second value, and the corresponding relationship; determining, based on an interpolation algorithm, the DCR corresponding to the parameter value of the first state parameter of the battery pack at the target moment according to the DCR corresponding to the first value and the DCR corresponding to the second value; and determining the DCR corresponding to the parameter value of the first state parameter of the battery pack as the DCR of the battery pack at the target moment.

[0011] In this implementation manner, in the correspondence relationship between multiple state parameter groups and multiple DCRs, if the parameter values of the multiple state parameter groups in this correspondence relationship do not include the parameter value of a certain state parameter in the state parameter group of the battery pack at the target moment. For example, the parameter value of the first state parameter in the state parameter group of the battery pack at the target moment is not equal to the value of the first state parameter in any of the state parameter groups in this correspondence relationship. Then, among the multiple values of the first state parameter in this correspondence relationship, the first value and the second value that are closest to the parameter value of the current first state parameter of the battery pack can be found, and the DCRs corresponding to the first value and the second value can be determined. Thus, through the interpolation algorithm, the DCR corresponding to the parameter value of the current first state parameter of the battery pack can be obtained.

[0012] In some possible implementation manners, obtaining the state parameter group of the battery pack at the current moment and the target moment includes: receiving the current of the battery pack at the target moment, the duration of the current, and the direction of the current sent by the Energy Management System (EMS); determining the State of Charge (SOC) of the battery pack at the target moment according to the current of the battery pack at the target moment, the duration of the current, the direction of the current, and the SOC of the battery pack at the current moment.

[0013] For example, determining the SOC of the battery pack at the target moment according to the current of the battery pack at the target moment, the duration of the current, the direction of the current, and the SOC of the battery pack at the current moment includes: determining the charge-discharge capacity of the battery pack from the current moment to the target moment according to the current of the battery pack at the target moment, the duration of the current, and the direction of the current; determining the SOC of the battery pack at the target moment according to the SOC of the battery pack at the current moment and the charge-discharge capacity.

[0014] In the above implementation manner, the EMS can send the operating condition information at the target moment in advance, such as the updated current and its duration and direction. Therefore, the SOC of the battery pack at the target moment can be determined according to the current SOC of the battery pack and the updated current and its duration and direction sent by the EMS. Then, in combination with the values of other state parameters at the target moment, the DCR of the battery pack at the target moment can be determined in the DCR database including the correspondence relationship between multiple state parameter groups and multiple DCRs.

[0015] In some possible implementation manners, the detection method further includes: determining whether there is uneven current sharing among the multiple battery packs at the target moment according to the DCRs of the multiple parallel-connected battery packs at the target moment.

[0016] In this implementation, when multiple battery packs are connected in parallel to the power grid, since the voltages of the multiple battery packs are the same, the DCR differences between the multiple battery packs will cause current differences between the battery packs based on Ohm's law, resulting in uneven current distribution among the multiple battery packs, which affects the capacity and power of the entire battery pack. Therefore, it is possible to detect the differences between the DCRs of the multiple parallel-connected battery packs to determine whether there is uneven current distribution among the multiple battery packs, so as to timely discover and prevent uneven current distribution between the parallel-connected battery packs.

[0017] For example, determining whether there is uneven current distribution among the multiple battery packs at the target moment according to the DCRs of the multiple parallel-connected battery packs at the target moment includes: 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, determining that there is uneven current distribution among the multiple battery packs at the target moment, 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.

[0018] 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 the multiple parallel-connected battery packs, it is possible to timely discover the uneven current distribution among the multiple battery packs.

[0019] In some possible implementation manners, the battery pack is a battery cluster or an electric cabinet, the battery cluster or the electric cabinet includes multiple electric boxes connected in series and / or in parallel, and the electric box includes multiple battery cells connected in series and / or in parallel.

[0020] The above-mentioned battery pack can be a battery cluster or an electric cabinet. The battery cluster or the electric cabinet includes multiple electric boxes connected in series and / or in parallel, and each electric box includes multiple battery cells connected in series and / or in parallel. Uneven current distribution may occur between other parallel units in the energy storage system. 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 timely discover and prevent uneven current distribution between these parallel units.

[0021] In a second aspect, a DCR detection device is provided. The detection device includes: an acquisition module configured to acquire a set of state parameters of a battery pack at a target moment after the current moment, where the set of state parameters includes at least one state parameter of the battery pack; and a processing module configured to determine the DCR of the battery pack at the target moment according to the set of state parameters of the battery pack at the target moment and a corresponding relationship between a preset set of multiple state parameters and multiple DCRs.

[0022] In some possible implementation manners, the state parameter group includes at least one of the following state parameters: the SOC of the battery pack, the temperature of the battery pack, the current of the battery pack, the charge and discharge direction of the battery pack, the charge and discharge time of the battery pack, and the SOH of the battery pack.

[0023] In some possible implementation manners, the processing module is specifically configured to determine the DCR corresponding to the state parameter group of the battery pack at the target moment among the plurality of DCRs as the DCR of the battery pack at the target moment.

[0024] In some possible implementation manners, the state parameter group includes a first state parameter, and the correspondence includes multiple values of the first state parameter corresponding to the plurality of DCRs. The processing module is specifically configured to determine, among the multiple values, a first value and a second value that are closest to the parameter value of the first state parameter of the battery pack at the target moment; determine the DCR corresponding to the first value and the DCR corresponding to the second value according to the first value, the second value, and the correspondence; determine the DCR corresponding to the parameter value of the first state parameter of the battery pack at the target moment based on an interpolation algorithm according to the DCR corresponding to the first value and the DCR corresponding to the second value; and determine the DCR corresponding to the parameter value of the first state parameter of the battery pack as the DCR of the battery pack at the target moment.

[0025] In some possible implementation manners, the acquisition module is specifically configured to receive the current of the battery pack at the target moment, the duration of the current, and the direction of the current sent by an energy management system (EMS); and determine the SOC of the battery pack at the target moment according to the current of the battery pack at the target moment, the duration of the current, the direction of the current, and the SOC of the battery pack at the current moment.

[0026] In some possible implementation manners, the acquisition module is specifically configured to determine the charge and discharge capacity of the battery pack from the current moment to the target moment according to the current of the battery pack at the target moment, the duration of the current, and the direction of the current; and determine the SOC of the battery pack at the target moment according to the SOC of the battery pack at the current moment and the charge and discharge capacity.

[0027] In some possible implementation manners, the processing module is specifically configured to determine whether there is uneven current sharing among the plurality of battery packs at the target moment according to the DCRs of the plurality of parallel-connected battery packs at the target moment.

[0028] In some possible implementation manners, the processing module is specifically configured to determine that the current sharing among the multiple battery packs is uneven at the target moment when the ratio between the DCR of the first battery pack and the DCR of the second battery pack in 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.

[0029] 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.

[0030] In a third aspect, a energy storage system is provided, including: a plurality of battery packs connected in parallel; and the DCR detection device according to the second aspect or any one of the possible implementation manners of the second aspect, where the detection device is configured to detect the DCR of the battery packs. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] To more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the accompanying drawings required to be used in the embodiments of the present application. Obviously, the following described accompanying drawings are only some embodiments of the present application. For those of ordinary skill in the art, other accompanying drawings can be obtained based on the accompanying drawings without creative efforts.

[0032] Figure 1 is a schematic diagram of a possible energy storage system according to an embodiment of the present application.

[0033] Figure 2 is a schematic diagram of a possible battery cluster according to an embodiment of the present application.

[0034] Figure 3 is a schematic diagram of a possible electric box according to an embodiment of the present application.

[0035] Figure 4 is a schematic flowchart of a DCR detection method according to an embodiment of the present application.

[0036] Figure 5 is a schematic diagram of a DCR calculation principle.

[0037] Figure 6 is Figure 4 a flowchart of a possible implementation manner of the DCR detection method shown.

[0038] Figure 7 is a schematic block diagram of a DCR detection device according to an embodiment of the present application.

[0039] Figure 8It is a schematic block diagram of the DCR detection device according to an embodiment of the present application. Detailed implementation manners

[0040] The following further describes the implementation manners of the present application in detail with reference to the accompanying drawings and embodiments. The detailed descriptions and the accompanying drawings of the following embodiments 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.

[0041] The following further describes the implementation manners of the present application in detail with reference to the accompanying drawings and embodiments. The detailed descriptions and the accompanying drawings of the following embodiments 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.

[0042] 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 electric 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 AC signal of the power grid and the DC signal of the energy storage system.

[0043] As an example, as Figure 1 shown, the energy storage system 1 includes N battery clusters, that is, 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, that is, 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 monomers. For example, as Figure 3 shown, each of the electrical boxes B1 to electrical box B M includes K battery monomers connected in series and / or in parallel.

[0044] When 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, affecting the capacity and power of the battery clusters. Therefore, it is not only necessary to detect the DCR of the battery clusters, but also to be able to predict the DCR of the battery clusters under future working conditions, so as to judge in advance whether uneven current distribution may occur between the battery clusters, timely determine appropriate strategies and make corresponding responses, thereby reducing the risk of high voltage under overcurrent caused by too large DCR difference between the battery clusters.

[0045] To this end, the present application provides a DCR detection solution. By establishing a DCR database that includes the correspondence between the state parameter group of the battery pack and DCR, when the state parameters of the battery pack under future working conditions are known, the DCR of the battery cluster under future working conditions can be predicted using this DCR database, so as to facilitate the early judgment of whether uneven current distribution may occur between battery clusters, timely determine appropriate strategies and make corresponding responses, thereby reducing the risks caused by excessive DCR differences between battery clusters.

[0046] Figure 4 FIG. shows the DCR detection method of 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 of an embodiment of the present application includes some or all of the following steps.

[0047] In step 110, obtain the state parameter group of the battery pack at the target time after the current time.

[0048] In step 120, according to the state parameter group of the battery pack at the target time and the preset correspondence between multiple state parameter groups and multiple DCRs, determine the DCR of the battery pack at the target time.

[0049] The state parameter group includes at least one state parameter of the battery pack, for example, includes at least one of the following state parameters: the SOC of the battery pack, the temperature of the battery pack, the current of the battery pack, the charge and discharge direction of the battery pack, the charge and discharge time of the battery pack, and the SOH of the battery pack and other various state parameters that may affect the DCR of the battery pack, comprehensively considering the influence of different influencing factors on the DCR of the battery pack.

[0050] Among them, SOC can, for example, represent the percentage of the remaining capacity of the battery; SOH can, for example, represent the percentage between the current capacity of the battery and the factory capacity, which is used to measure the aging state of the battery; the charge and discharge direction of the battery pack includes charging and discharging, that is, the positive or negative of the current; the charge and discharge time can, for example, refer to the time that the current lasts.

[0051] Due to its electrochemical characteristics, the internal resistance of a battery may be affected by multiple factors. To more accurately detect the DCR of a battery pack, first, it is necessary to identify the influencing factors associated with the DCR of the battery pack. The embodiments of the present application provide multiple influencing factors that may affect the DCR of a battery pack, including the SOC of the battery pack, the temperature T of the battery pack, the current I of the battery pack, the charge and discharge direction of the battery pack, the charge and discharge time Time of the battery pack, and the SOH of the battery pack. Among them, for the charging state or the discharging state, the DCR of the battery pack = f(SOC, SOH, I, Time, T, charge and discharge direction), where f is the relationship between these state parameters and the DCR, that is, the corresponding relationship between the above-mentioned multiple state parameter groups and multiple DCRs.

[0052] 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 multiple battery boxes connected in series and / or in parallel, and each battery box includes multiple battery cells connected in series and / or in parallel. Among them, the electric cabinet can be regarded as a battery product formed by a battery cluster. Therefore, the battery cluster in the embodiments of the present application can also be replaced by an electric cabinet. Multiple electric cabinets can be assembled to form a container. Hereinafter, taking the battery cluster shown in Figures 1 to 3 as an example, the DCR detection method 100 of the embodiments of the present application will be described in detail. Of course, in addition to the possible uneven current distribution among multiple parallel-connected battery clusters, there may also be uneven current distribution among other units that need to be connected in parallel in the energy storage system. The DCRs of these parallel-connected units can also be determined by the method 100 to facilitate timely discovery and prevention of the uneven current distribution among these parallel-connected units.

[0053] In the embodiments of the present application, by establishing a DCR database including the corresponding relationship between the state parameter group of the battery pack and the DCR, when the state parameters of the battery pack at any moment are known, the DCR of the battery pack at that moment can be determined. For example, when the state parameters of the battery pack under future working conditions are known, the DCR of the battery pack under future working conditions can be predicted using this DCR database, and risk prediction can be performed based on this DCR. For example, it can be determined in advance whether uneven current distribution may occur between battery packs, and appropriate strategies can be determined and corresponding responses can be made in a timely manner, thereby reducing the risk caused by excessive DCR differences between battery packs.

[0054] Among them, the target moment after the current moment of the battery pack can refer to any moment after the current moment when it is necessary to predict the DCR of the battery pack. For example, when it is determined that the state parameters in the state parameter group of the battery pack have changed, the DCR of the battery pack at the target moment after the current moment can be predicted.

[0055] The temperature, SOH, SOC at the current moment, etc. of the battery pack can be calculated by the BMS itself, and the probability of changes in the temperature and SOH of the battery pack in a short period of time is relatively low. Therefore, the changes in the state parameters mainly include the changes in the current of the battery pack, including changes in parameters such as the magnitude, direction, and duration of the current. At this time, in some embodiments, the energy management system (EMS) can send the new current information to the BMS, and the BMS receives the current information of the battery pack at the target moment sent by the EMS, such as the magnitude of the current, the duration of the current, and the direction of the current, and determines the SOC of the battery pack at the target moment according to the current of the battery pack at the target moment, the duration of the current, the direction of the current, and the SOC of the battery pack at the current moment.

[0056] For example, the charge-discharge capacity of the battery pack from the current moment to the target moment can be determined according to the current of the battery pack at the target moment, the duration of the current, and the direction of the current, and the SOC of the battery pack at the target moment can be determined according to the SOC of the battery pack at the current moment and the charge-discharge capacity.

[0057] That is to say, the SOC of the battery pack at the target moment can be calculated according to the current of the battery pack at the target moment, its direction, and the charge-discharge time. The battery pack receives the new current I sent by the EMS, the duration T of the current I, and the charge-discharge direction, that is, the positive and negative of the current I. Assuming that charging starts from the current moment with the new current I, the charge-discharge capacity △Q of the battery pack based on the current I within the duration T is △Q = I * T / Q, where T is the duration of charge-discharge based on the current I from the current moment to the target moment, and Q is the capacity of the battery pack, such as the rated capacity or the maximum capacity. If the battery pack is charged to the target moment, then SOC2 = SOC1 + △Q = SOC * 1 + I * T / Q, where SOC1 is the SOC of the battery pack at the current moment, and SOC2 is the value of the SOC of the battery pack at the target moment; if the battery pack is discharged to the target moment, SOC3 = SOC1 - △Q = SOC1 - I * T / Q, where SOC1 is the SOC of the battery pack at the current moment, and SOC3 is the value of the SOC of the battery pack at the target moment.

[0058] After that, according to SOC2 or SOC3, and other state parameters of the battery pack at the target moment, such as temperature and SOH, the DCR corresponding to these state parameters is searched in the DCR database as the DCR of the battery pack at the target moment.

[0059] Optionally, when the BMS determines that state parameters of the battery pack change, such as parameters related to current, it can predict the DCR of the battery pack under the changed state parameters. For example, when it is known that the current charges and discharges based on the new current I from the current moment until the target moment, the BMS can determine the SOC of the battery pack at the target moment according to the SOC of the battery pack at the current moment and the parameters related to the current I, and combine other state parameters at the target moment to predict the DCR of the battery pack at the target moment. In other embodiments, the BMS can also predict the DCR of the battery pack at the target moment based on a certain period.

[0060] It can be seen that the EMS sends the operating condition information at the target moment in advance, such as including the updated current and its duration and direction, so that the SOC of the battery pack at the target moment can be determined according to the current SOC of the battery pack and the updated current and its duration and direction sent by the EMS. Then, in combination with the values of other state parameters at the target moment, the DCR of the battery pack at the target moment is determined in the DCR database including the correspondence between multiple state parameter groups and multiple DCRs.

[0061] Hereinafter, the establishment process of the correspondence between multiple state parameter groups and multiple DCRs will be described in detail.

[0062] After determining various state parameters that may affect the DCR of the battery, the value of each state parameter in the DCR test process can be designed. For example, as shown in Table 1, for various state parameters that may affect the DCR, including SOC, temperature, current, charge and discharge direction, charge and discharge time, and SOH, a reasonable value range matching the actual operating conditions of the battery is set. Here, only the example where the charging time is in the range of 5s - 60s and the charging current is in the range of 120A - 180A is taken. In practical applications, a longer charging time range and / or a larger current range can be set.

[0063] Table 1

[0064] Number Status parameter Value of the status parameter 1 SOC Value taken at every 5% SOC interval 2 Temperature T Value taken at every 5% interval within the operating temperature range of the battery 3 Current I Value taken at every 5 A interval within the range of 120 A - 180 A 4 Charge and discharge time T Value taken at every 5 s interval within the range of 5 s - 60 s 5 Charge and discharge direction Charge or discharge 6 Aging state Value taken at every 5% SOH interval

[0065] In the test process, the method of controlling variables is adopted. According to the value requirements described in Table 1, the value of each of the 6 state parameters in Table 1 is changed separately, and a series of DCR tests for the values of this state parameter are carried out.

[0066] For example, a fresh battery cell is taken as the test object, 100% SOH, the test environment temperature is 25°C, and the charging current is kept constant at 140A under the charging state. Under this condition, the DCR of the battery cell under different SOCs is tested, and the values of SOC include 0%, 5%, 10%, 15%,..., 95%, 100%.

[0067] First, for the DCR test under the condition that the SOC is 0%, adjust the SOC of the battery cell to 0%, fully static for a period of time such as 2 hours, charge the battery cell at a current of 140 A for 60 s, and record the voltages of the battery cell at multiple moments. For example, as shown in Table 2, under the condition that the SOC is 0%, record the voltages of the battery cell within the charging time of 5 s - 60 s at a time interval of 5 s.

[0068] Table 2

[0069] Charge and discharge time T / s 0 5 10 15 20 …… 55 60 Voltage / V <![CDATA[U0]]> <![CDATA[U5]]> <![CDATA[U 10 > <![CDATA[U 15 > <![CDATA[U 20 > …… <![CDATA[U 55 > <![CDATA[U 60 >

[0070] According to Table 2, the DCR of the battery cell can be calculated under different charging durations. As an example, the DCR test principle shown Figure 5 can be used to calculate the DCR of the battery cell. As shown Figure 5 , after charging the battery cell at a constant current I for a certain duration △T, the DCR of the battery cell can be determined based on the voltage U, current I, and the initial voltage U0 of the battery cell at the moment after this duration △T. Among them, DCR = (U - U0) / I.

[0071] In Table 2, U0 is the initial voltage, that is, the static voltage. Then, the DCR of the battery cell at the time of charging for 0 s is DCR 01 , the DCR of the battery cell at the time of charging for 5 s 02 = (U5 - U0) / I, the DCR of the battery cell at the time of charging for 10 s 03 = (U 10 - U0) / I, the DCR of the battery cell at the time of charging for 15 s 04 = (U 15 - U0) / I, the DCR of the battery cell at the time of charging for 20 s 05 = (U 20 - U0) / I, ……, the DCR of the battery cell at the time of charging for 55 s 06 = (U 55 - U0) / I, the DCR of the battery cell at the time of charging for 60 s 07 = (U 60 - U0) / I, where I = 140 A.

[0072] In this way, the corresponding relationship between the charging time and the DCR can be obtained as shown in Table 3 under the conditions of meeting 100% SOH, a test environment temperature of 25 °C, a constant charging current of 140 A in the charging state, and an SOC of 0%.

[0073] Table 3

[0074] Charge and discharge time T / s 0 5 10 15 20 …… 55 60 DCR <![CDATA[DCR 01 > <![CDATA[DCR 02 > <![CDATA[DCR 03 > <![CDATA[DCR 04 > <![CDATA[DCR 05 > …… <![CDATA[DCR 06 > <![CDATA[DCR 07 >

[0075] Secondly, adjust the SOC of the battery cell to 5%, and perform the test according to the above operations. Similarly, the corresponding relationship between the charging time and the DCR can be obtained under the conditions of meeting 100% SOH, a test ambient temperature of 25°C, a constant charging current of 140A in the charging state, and an SOC of 5%, as shown in Table 3.

[0076] Subsequently, adjust the SOC of the battery cell at intervals of 5% SOC, and perform the DCR test according to the above operations. The DCR mapping table under the conditions of 100% SOH, a test ambient temperature of 25°C, a constant charging current of 140A in the charging state, and SOC values of 0%, 5%, 10%, 15%, …, 95%, 100%, and charging times of 0s, 5s, 15s, …, 60s can be obtained. For example, the corresponding relationship between the state parameter group composed of the charging time and the SOC and the DCR, as shown in Table 4.

[0077] Table 4

[0078]

[0079] In the same way, successively change the values of the remaining state parameters such as temperature, current, and SOH, and complete the DCR tests for a series of values under other state parameters through the single-factor control variable method. Summarize the DCR data for all state parameters at different values to obtain the corresponding relationship between the state parameter group composed of SOC, temperature, current, charge and discharge direction, charge and discharge time, and SOH and the DCR, thereby establishing a multi-dimensional full-life cycle DCR database for the battery.

[0080] This DCR database includes the corresponding relationships between multiple state parameter groups and the DCR, and this DCR database can be written into the BMS software, for example. In the actual application process, the state parameter group of the battery pack can be collected, including the SOC, temperature, current, charge and discharge direction, charge and discharge time, and SOH of the battery pack, and the DCR corresponding to the parameter values of each state parameter in this state parameter group of the battery pack can be found from the DCR database stored in the BMS.

[0081] The corresponding relationship between each state parameter in the state parameter group and DCR can be implemented in various forms. For example, the corresponding relationship between each state parameter in the state parameter group and DCR can be a table of the mapping relationship between the values of each state parameter and DCR; it can also be a curve or formula for representing the corresponding relationship between each state parameter in the state parameter group and DCR, such as DCR = f(SOC, SOH, I, Time, T, charge and discharge direction); or other forms that can represent the corresponding relationship between each state parameter in the state parameter group and DCR. Among them, Tables 1 to 4 take the form of a mapping table as an example, and store the mapping relationship between each state parameter in the state parameter group and DCR in the BMS in the form of a mapping table.

[0082] In one implementation, in step 120, the DCR corresponding to the state parameter group of the battery pack at the target moment among the multiple DCRs in the DCR database can be directly determined as the DCR of the battery pack at the target moment, so as to simply and quickly predict the DCR of the battery pack.

[0083] In another implementation, in step 120, for the parameter values between the adjacent values in the DCR database, the DCR corresponding to the parameter value can be calculated through an interpolation algorithm such as a linear interpolation algorithm. Assume that the state parameter group includes a first state parameter, and the DCR database includes multiple values of the first state parameter corresponding to multiple DCRs. If the parameter value of the first state parameter in the state parameter group of the battery pack at the target moment is not equal to any of the multiple values of the first state parameter in the DCR database, then, among the multiple values of the first state parameter in the corresponding relationship, the first value and the second value closest to the parameter value of the first state parameter of the battery pack at the target moment can be found, and the DCRs corresponding to the first value and the second value can be determined, so as to obtain the DCR corresponding to the parameter value of the first state parameter of the battery pack at the target moment through the interpolation algorithm.

[0084] Specifically, in step 120, the first value and the second value closest to the parameter value of the first state parameter of the battery pack at the target moment can be determined among the multiple values of the first state parameter in the DCR database; according to the first value, the second value, and the corresponding relationship between the first parameter value and DCR in the DCR database, the DCR corresponding to the first value and the DCR corresponding to the second value can be determined; according to the DCR corresponding to the first value and the DCR corresponding to the second value, based on the interpolation algorithm, the DCR corresponding to the parameter value of the first state parameter of the battery pack can be determined; and the DCR corresponding to the parameter value of the first state parameter of the battery pack at the target moment can be determined as the DCR of the battery pack at the target moment.

[0085] Taking the SOC as an example, assume that the parameter values of each state parameter in the state parameter group of the battery pack at the target moment are as follows: SOH is 100%, the test environment temperature is 25°C, the charging current is constant at 140A under the charging state, the charging duration is 60s, and the SOC is 8%. If the SOC in the DCR database is at intervals of 5%, including the DCR corresponding to SOC of 0%, 5%, 10%, 15%, ……, 95%, 100%. Then, the SOC values closest to 8% SOC are 5% and 10%. The DCR under the conditions of SOH being 100%, the test environment temperature being 25°C, the charging current being constant at 140A under the charging state, the charging duration being 60s, and the SOC being 5% can be found respectively, and the DCR under the conditions of SOH being 100%, the test environment temperature being 25°C, the charging current being constant at 140A under the charging state, the charging duration being 60s, and the SOC being 10%.

[0086] Assume that the values of DCR corresponding to 5% SOC and 10% SOC are DCR 16 and DCR 26 , then, according to the linear interpolation algorithm, the DCR under the conditions of SOH being 100%, the test environment temperature being 25°C, the charging current being constant at 140A under the charging state, the charging duration being 60s, and the SOC being 8% can be obtained: DCR = DCR 16 +(DCR 26 -DCR 16 )*(8% - 5%) / (10% - 5%) = DCR 16 +3(DCR 26 -DCR 16 ) / 5.

[0087] 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 difference between multiple battery packs will cause a current difference between the battery packs, resulting in an uneven current distribution among the multiple battery packs, which affects the capacity and power of the battery cluster. Therefore, in some embodiments, the detection method 100 may further include: determining whether there is an uneven current distribution among the multiple parallel-connected battery packs according to the DCR of the multiple parallel-connected battery packs at the target moment. That is, by detecting the DCR of the multiple parallel-connected battery packs at the target moment, it is possible to predict whether there may be an uneven current distribution among the multiple battery packs at the target moment, so as to timely discover and prevent the uneven current distribution between the parallel-connected battery packs.

[0088] Optionally, it is possible to determine whether there is an uneven current distribution among the multiple battery packs according to the difference between the DCRs of the multiple parallel-connected battery packs at the target moment. For example, the difference between the DCR of the first battery pack and the DCR of the second battery pack among the multiple battery packs, 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.

[0089] For example, it is possible to determine uneven current sharing between 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; for another example, it is possible to determine uneven current sharing between 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.

[0090] 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 sharing situation between multiple battery packs.

[0091] As an example, as Figure 6 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 work 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.

[0092] As Figure 6 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.

[0093] In step 102, the MBMU receives the current information at the target moment sent by the EMS, for example, including the magnitude, direction, and duration T of the current I, and sends this current information to the SBMU.

[0094] In step 103, the SBMU calculates the SOC of the battery cluster at the target moment based on this current information and the current SOC of the battery cluster.

[0095] In step 104, the SBMU determines the SOH and temperature of the battery cluster at the target moment.

[0096] In step 105, the SBMU determines the actual DCR of the battery cluster at the target moment based on the SOH, SOC, temperature, and current information of the battery cluster at the target moment, such as the magnitude, direction, and duration of the current, and the DCR database.

[0097] For example, the DCR found in the DCR database can be used as the actual DCR of the battery cluster at the target moment; or, when the DCR database does not include the parameter value of a certain state parameter at the target moment, a value adjacent to this parameter value is selected in the DCR database, and the DCR corresponding to this parameter value is calculated through an interpolation algorithm and used as the actual DCR of the battery cluster at the target moment.

[0098] Among them, the SBMU can report the DCR of the corresponding battery cluster at the target time to the MBMU.

[0099] In step 106, the MBMU calculates the internal resistance difference between clusters at the target time according to the DCRs of multiple parallel-connected battery clusters at the target time.

[0100] For example, the internal resistance difference can be represented by DCRmax / DCRmin, where DCRmax and DCRmin respectively represent the maximum DCR and the minimum DCR among the DCRs of multiple battery clusters at the target time.

[0101] In step 107, the MBMU determines whether the internal resistance difference between clusters DCRmax / DCRmin is greater than a preset DCR threshold, and this DCR threshold is denoted as x%, for example, where x is a preset value.

[0102] When the internal resistance difference between clusters DCRmax / DCRmin is greater than the DCR threshold x%, that is, when DCRmax / DCRmin > x%, step 108 is executed; when the internal resistance difference between clusters DCRmax / DCRmin 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.

[0103] In step 108, an uneven current sharing strategy to be adopted is prepared in advance.

[0104] This 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.

[0105] The detection method of DCR in the embodiments of the present application is described in detail above. Next, in combination with Figure 7 and Figure 8 The detection device of DCR in 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.

[0106] The embodiments of the present application also provide a DCR detection device 200. As Figure 7 shown, the detection device 200 includes an acquisition module 210 and a processing module 220.

[0107] Among them, the acquisition module 210 is used to obtain a set of state parameters of the battery pack at a target time after the current time, and the set of state parameters includes at least one state parameter of the battery pack.

[0108] The processing module 220 is used to determine the DCR of the battery pack at the target time according to the set of state parameters of the battery pack at the target time and the corresponding relationship between a preset set of multiple state parameters and multiple DCRs.

[0109] The state parameter group includes, for example, at least one of the following state parameters: the state of charge SOC of the battery pack, the temperature of the battery pack, the current of the battery pack, the charge and discharge direction of the battery pack, the charge and discharge time of the battery pack, and the state of health SOH of the battery pack.

[0110] The battery pack is, for example, a battery cluster or an electric cabinet, and the battery cluster or the electric cabinet includes a plurality of electric boxes connected in series and / or in parallel, and the electric box includes a plurality of battery cells connected in series and / or in parallel.

[0111] In some embodiments, the processing module 220 is specifically configured to determine the DCR corresponding to the state parameter group of the battery pack at the target moment among the plurality of DCRs as the DCR of the battery pack at the target moment.

[0112] In some embodiments, the state parameter group includes a first state parameter, and the correspondence includes a plurality of values of the first state parameter corresponding to the plurality of DCRs. The processing module 220 is specifically configured to determine, among the plurality of values, the first value and the second value that are closest to the parameter value of the first state parameter of the battery pack at the target moment; determine the DCR corresponding to the first value and the DCR corresponding to the second value according to the first value, the second value, and the correspondence; determine the DCR corresponding to the parameter value of the first state parameter of the battery pack at the target moment based on the interpolation algorithm according to the DCR corresponding to the first value and the DCR corresponding to the second value; and determine the DCR corresponding to the parameter value of the first state parameter of the battery pack as the DCR of the battery pack at the target moment.

[0113] In some embodiments, the acquisition module 210 is specifically configured to receive the current, the duration of the current, and the direction of the current of the battery pack at the target moment sent by the energy management system EMS; and determine the SOC of the battery pack at the target moment according to the current, the duration of the current, the direction of the current of the battery pack at the target moment, and the SOC of the battery pack at the current moment.

[0114] In some embodiments, the acquisition module 210 is specifically configured to determine the charge and discharge capacity of the battery pack from the current moment to the target moment according to the current, the duration of the current, and the direction of the current of the battery pack at the target moment; and determine the SOC of the battery pack at the target moment according to the SOC of the battery pack at the current moment and the charge and discharge capacity.

[0115] In some embodiments, the processing module 220 is specifically configured to determine whether there is uneven current sharing among the plurality of battery packs at the target moment according to the DCRs of the plurality of parallel-connected battery packs at the target moment.

[0116] In some embodiments, the processing module 220 is specifically configured to determine that there is uneven current sharing among multiple battery packs at a target moment when the ratio between the DCR of a first battery pack and the DCR of a 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.

[0117] It should be understood that the specific manner of DCR detection by the detection device 200 and the beneficial effects produced can be referred to the relevant descriptions in the method embodiments. For the sake of simplicity, they will not be elaborated here.

[0118] This application also provides an energy storage system, such as Figure 1 the energy storage system 1 shown in. The energy storage system 1 includes a plurality of battery packs connected in parallel, 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 packs.

[0119] This application also provides a computer-readable storage medium for storing a computer program. When the computer program is executed by a computing device, the computing device is enabled to implement the DCR detection method 100 described in any of the above embodiments. Optionally, the computer program can be the computer program in the BMS.

[0120] This application also provides 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 8 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.

[0121] Optionally, as Figure 8 shown, the detection device 300 can further include a transceiver 330. 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.

[0122] 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 instructions in the form of software. The above 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 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 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.

[0123] 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 ROM (PROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (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 RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchlink DRAM (SLDRAM), and direct rambus RAM (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.

[0124] 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.

[0125] In the embodiments of the present application, the magnitudes of the serial numbers of the respective steps do not mean the sequence of execution, and the execution sequence of each step should be determined according to its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0126] 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 technician can use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of the present application.

[0127] 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 coupling, direct coupling, or communication connection to each other can be through some interfaces. The indirect coupling or communication connection of the devices or units can be in electrical, mechanical, or other forms.

[0128] 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 they may be 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.

[0129] 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 direct current resistance, characterized in that The detection method includes: Obtaining a state parameter group of the battery pack at a target time after the current time, where the state parameter group includes at least one state parameter of the battery pack; Determining the DC resistance of the battery pack at the target time according to the state parameter group of the battery pack at the target time and a preset corresponding relationship between a plurality of state parameter groups and a plurality of DC resistances.

2. The detection method according to claim 1, wherein The state parameter group includes at least one of the following state parameters: The state of charge of the battery pack, the temperature of the battery pack, the current of the battery pack, the charge and discharge direction of the battery pack, the charge and discharge time of the battery pack, and the health state of the battery pack.

3. The detection method according to claim 1 or 2, characterized in that, The determining the DC resistance of the battery pack at the target time according to the state parameter group of the battery pack at the target time and a preset corresponding relationship between a plurality of state parameter groups and a plurality of DC resistances includes: Determining the DC resistance corresponding to the state parameter group of the battery pack at the target time among the plurality of DC resistances as the DC resistance of the battery pack at the target time.

4. The detection method according to claim 1 or 2, characterized in that The state parameter group includes a first state parameter, and the corresponding relationship includes a plurality of values of the first state parameter corresponding to the plurality of DC resistances. The determining the DC resistance of the battery pack at the target time according to the state parameter group of the battery pack at the target time and a preset corresponding relationship between a plurality of state parameter groups and a plurality of DC resistances includes: Determining a first value and a second value that are closest to the parameter value of the first state parameter of the battery pack at the target time among the plurality of values; Determining the DC resistance corresponding to the first value and the DC resistance corresponding to the second value according to the first value, the second value, and the corresponding relationship; Determining the DC resistance corresponding to the parameter value of the first state parameter of the battery pack at the target time based on an interpolation algorithm according to the DC resistance corresponding to the first value and the DC resistance corresponding to the second value; Determining the DC resistance corresponding to the parameter value of the first state parameter of the battery pack as the DC resistance of the battery pack at the target time.

5. The detection method according to any one of claims 1 to 4, characterized in that, The obtaining the state parameter group of the battery pack at the target time after the current time includes: Receiving the current of the battery pack at the target time, the duration of the current, and the direction of the current sent by the energy management system; Determining the state of charge of the battery pack at the target time according to the current of the battery pack at the target time, the duration of the current, the direction of the current, and the state of charge of the battery pack at the current time.

6. The detection method according to claim 5, wherein The determining the state of charge of the battery pack at the target time according to the current of the battery pack at the target time, the duration of the current, the direction of the current, and the state of charge of the battery pack at the current time includes: Determining the charge and discharge capacity of the battery pack from the current time to the target time according to the current of the battery pack at the target time, the duration of the current, and the direction of the current. Determine the state of charge of the battery pack at the target moment according to the state of charge of the battery pack at the current moment and the charge and discharge capacity.

7. The detection method according to any one of claims 1 to 6, characterized in that, The detection method further includes: Determine whether there is uneven current sharing among the multiple battery packs at the target moment according to the DC resistances of the multiple parallel-connected battery packs at the target moment.

8. The detection method according to claim 7, wherein The determining whether there is uneven current sharing among the multiple battery packs at the target moment according to the DC resistances of the multiple parallel-connected battery packs at the target moment 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 a preset DC resistance threshold, determine that there is uneven current sharing among the multiple battery packs at the target moment, 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.

9. The detection method according to any one of claims 1 to 8, characterized in that, The battery pack is a battery cluster or an electric cabinet, the battery cluster or the electric cabinet includes multiple electrical boxes connected in series and / or in parallel, and the electrical box includes multiple battery cells connected in series and / or in parallel.

10. A detection device for DC resistance, characterized in that, The detection device includes: An acquisition module for acquiring a set of state parameters of the battery pack at a target moment after the current moment, where the set of state parameters includes at least one state parameter of the battery pack; A processing module for determining the DC resistance of the battery pack at the target moment according to the set of state parameters of the battery pack at the target moment and a corresponding relationship between multiple sets of state parameters and multiple DC resistances preset.

11. The detection device according to claim 10, wherein The set of state parameters includes at least one of the following state parameters: The state of charge of the battery pack, the temperature of the battery pack, the current of the battery pack, the charge and discharge direction of the battery pack, the charge and discharge time of the battery pack, and the health state of the battery pack.

12. The detection device according to claim 10 or 11, characterized in that, Specifically, the processing module is used to: Determine the DC resistance corresponding to the set of state parameters of the battery pack at the target moment among the multiple DC resistances as the DC resistance of the battery pack at the target moment.

13. The detection device according to claim 10 or 11, characterized in that, The set of state parameters includes a first state parameter, and the corresponding relationship includes multiple values of the first state parameter corresponding to the multiple DC resistances. Specifically, the processing module is used to: Among the multiple values, determine a first value and a second value that are closest to the parameter value of the first state parameter of the battery pack at the target moment; According to the first value, the second value, and the corresponding relationship, determine the DC resistance corresponding to the first value and the DC resistance corresponding to the second value; Based on the interpolation algorithm, determine the DC resistance corresponding to the parameter value of the first state parameter of the battery pack at the target moment according to the DC resistance corresponding to the first value and the DC resistance corresponding to the second value; Determine the DC resistance corresponding to the parameter value of the first state parameter of the battery pack as the DC resistance of the battery pack at the target moment.

14. The detection device according to any one of claims 10 to 13, characterized in that, Specifically, the acquisition module is used to: Receive the current of the battery pack at the target moment, the duration of the current, and the direction of the current sent by the energy management system; Determine the state of charge of the battery pack at the target moment according to the current of the battery pack at the target moment, the duration of the current, the direction of the current, and the state of charge of the battery pack at the current moment.

15. The detection device according to claim 14, characterized in that, Specifically, the acquisition module is configured to Determine the charge-discharge capacity of the battery pack from the current moment to the target moment according to the current of the battery pack at the target moment, the duration of the current, and the direction of the current; Determine the state of charge of the battery pack at the target moment according to the state of charge of the battery pack at the current moment and the charge-discharge capacity.

16. The detection device according to any one of claims 10 to 15, characterized in that, Specifically, the processing module is configured to Determine whether there is uneven current sharing among the multiple battery packs at the target moment according to the DC resistance of the multiple parallel-connected battery packs at the target moment.

17. The detection device according to claim 16, characterized in that, Specifically, the processing module is 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 a preset DC resistance threshold, determine that there is uneven current sharing among the multiple battery packs at the target moment, 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.

18. The detection device according to any one of claims 10 to 17, characterized in that, The battery pack is a battery cluster or an electric cabinet, and the battery cluster or the electric cabinet includes multiple electric boxes connected in series and / or in parallel, and each electric box includes multiple battery cells connected in series and / or in parallel.

19. An energy storage system, characterized in that, Comprising: Multiple parallel-connected battery packs; And The DC resistance detection device according to any one of claims 10 to 18, where the detection device is configured to detect the DC resistance of the battery pack.

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