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 is acquired, and the state parameter set comprises at least two state parameters of the battery pack; and determining the DCR of the battery pack according to the state parameter group of the battery pack and a preset corresponding relationship between a plurality of state parameter groups and a plurality of DCRs. By establishing the database comprising the corresponding relation between the state parameter group of the battery pack and the DCR, the DCR of the battery pack under the current state parameter is determined by using the database, the influence of different influence factors on the DCR of the battery pack is comprehensively considered, and the accuracy of the DCR can be improved.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to a method and device for detecting direct current resistance (DCR) and an energy storage system. [[ID=k]] Background Art

[0002] Energy storage systems usually have requirements such as high voltage and large capacity. For this reason, 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 where the consistency between multiple battery packs is poor, 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, where the set of state parameters includes at least two state parameters of the battery pack; and determining the DCR of the battery pack according to the set of state parameters of the battery pack and a preset correspondence between multiple sets of state parameters and multiple DCRs.

[0005] In the embodiments of the present application, by establishing a database including the correspondence between the set of state parameters of the battery pack and DCR, the DCR of the battery pack under the current state parameters is determined by using the database. The set of state parameters includes various state parameters that may affect the DCR of the battery pack. Since the influence of different state parameters on the DCR of the battery pack is comprehensively considered, the accuracy of DCR can be improved.

[0006] In some possible implementation manners, the set of state parameters includes at least two 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] The state parameter group includes, for example, 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 factors on the DCR of the battery pack.

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

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

[0010] In some possible implementation manners, 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. Determining the DCR of the battery pack according to the state parameter group of the battery pack and a preset correspondence between a plurality of state parameter groups and a plurality of DCRs 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 among the plurality of values; 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 correspondence; determining the DCR corresponding to the parameter value of the first state parameter of the battery pack based on an interpolation algorithm 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.

[0011] In this implementation manner, in the correspondence between a plurality of state parameter groups and a plurality of DCRs, if the parameter values of the plurality of state parameter groups in the correspondence do not include the parameter value of a certain state parameter in the current state parameter group of the battery pack, for example, the parameter value of the first state parameter in the state parameter group of the battery pack is not equal to the value of the first state parameter in any of the state parameter groups in the correspondence, then, among the plurality of values of the first state parameter in the correspondence, the first value and the second value that are closest to the parameter value of the 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, so as to obtain the DCR corresponding to the parameter value of the first state parameter of the battery pack through an interpolation algorithm.

[0012] 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 DCR of the multiple parallel-connected battery packs.

[0013] In this implementation manner, when multiple battery packs are connected in parallel to the power grid, according to Ohm's law, since the voltages of the multiple battery packs are the same, the DCR difference among the multiple battery packs will cause a current difference among the battery packs, resulting in uneven current sharing among the multiple battery packs, which affects 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 difference in DCR among the multiple parallel-connected battery packs, so as to timely discover and prevent uneven current sharing among the parallel-connected battery packs.

[0014] For example, the determining whether there is uneven current sharing among the multiple battery packs according to the DCR of the multiple parallel-connected battery packs 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 sharing 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.

[0015] 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 sharing situation among the multiple battery packs.

[0016] 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.

[0017] 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 sharing may occur among other parallel units in the energy storage system, and the DCR 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 sharing among these parallel units.

[0018] 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, where the set of state parameters includes at least two state parameters of the battery pack; and a processing module, configured to determine the DCR of the battery pack according to the set of state parameters of the battery pack and a preset corresponding relationship between multiple sets of state parameters and multiple DCRs.

[0019] In some possible implementations, the state parameter group includes at least two 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.

[0020] In some possible implementations, the processing module is specifically configured to determine the DCR of the battery pack as the DCR corresponding to the state parameter group of the battery pack among the multiple DCRs.

[0021] In some possible implementations, the state parameter group includes a first state parameter, and the correspondence includes multiple values of the first state parameter corresponding to the multiple 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; 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 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.

[0022] In some possible implementations, the processing module is further configured to determine whether there is uneven current sharing among the multiple battery packs according to the DCRs of the multiple parallel-connected battery packs.

[0023] In some possible implementations, the processing module is specifically configured to determine 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.

[0024] In some possible implementations, 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.

[0025] In a third aspect, a energy storage system is provided, including: multiple battery packs connected in parallel; and the DCR detection device according to 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. Description of the Drawings

[0026] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the accompanying drawings required for use in the embodiments of the present application. Obviously, the accompanying drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on the accompanying drawings.

[0027] Figure 1 It is a schematic diagram of a possible energy storage system according to an embodiment of the present application.

[0028] Figure 2 It is a schematic diagram of a possible battery cluster according to an embodiment of the present application.

[0029] Figure 3 It is a schematic diagram of a possible electrical box according to an embodiment of the present application.

[0030] Figure 4 It is a schematic flowchart of a method for detecting DCR according to an embodiment of the present application.

[0031] Figure 5 It is a schematic diagram of the DCR calculation principle.

[0032] Figure 6 It is Figure 4 A flowchart of a possible implementation manner of the DCR detection method shown.

[0033] Figure 7 It is a schematic block diagram of a DCR detection device according to an embodiment of the present application.

[0034] Figure 8 It is a schematic block diagram of a DCR detection device according to an embodiment of the present application. Specific embodiments

[0035] The following will further describe the implementation manners of the present application in detail in conjunction with the accompanying drawings and embodiments. The following detailed description of the embodiments and the accompanying drawings are used to exemplarily illustrate the principle of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0036] 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 AC signal of the power grid and the DC signal of the energy storage system.

[0037] 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. Battery clusters R1 to battery cluster R NThey are connected in parallel with each other and are charged or discharged through the PCS to / from the power grid. Each battery cluster includes a plurality of electrical boxes. For example, as Figure 2 shown, each of the battery clusters from battery cluster R1 to battery cluster R N includes M electrical boxes, that is, electrical boxes B1 to 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. Each electrical box is assembled by K battery cells. For example, as Figure 3 shown, each of the electrical boxes from electrical box B1 to B M includes K battery cells connected in series and / or in parallel, that is, battery cells C1 to C K .

[0038] 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 and affecting the capacity and power of the battery clusters. Therefore, it is necessary to detect the DCR of the battery clusters.

[0039] However, the DCR is affected by various factors, resulting in a deviation between the DCR of the battery under actual operating conditions and the initial DCR of the battery.

[0040] For this reason, the present application provides a DCR detection solution. By establishing a DCR database including the correspondence between the state parameter group of the battery pack and the DCR, the DCR of the battery pack under the current state parameters is determined using this DCR database, where the state parameter group includes various state parameters that may affect the DCR of the battery pack, such as the state of charge (SOC), temperature, state of health (SOH) of the battery, charge and discharge direction, charge and discharge time, and charge and discharge current, etc. Since the influence of different state parameters on the DCR of the battery pack is comprehensively considered, the accuracy of the DCR is improved.

[0041] Figure 4 shows the DCR detection method of the 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 the embodiment of the present application includes some or all of the following steps.

[0042] In step 110, obtain the state parameter group of the battery pack.

[0043] In step 120, determine the DCR of the battery pack according to the state parameter group of the battery pack and the corresponding relationship between multiple preset state parameter groups and multiple DCRs.

[0044] 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 multiple state parameters that may affect the DCR of the battery pack.

[0045] Among them, the SOC can represent, for example, the percentage of the remaining capacity of the battery; the SOH can represent, for example, the percentage between the 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 be, for example, the time that the current lasts.

[0046] Due to its electrochemical characteristics, the internal resistance of the battery may be affected by multiple factors. In order to more accurately detect the DCR of the 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 the 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 multiple state parameter groups and the multiple DCRs described above.

[0047] 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 electrical boxes connected in series and / or in parallel, and each electrical 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 the 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 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 DCRs of these parallel-connected units can also be determined by the method 100 to facilitate timely discovery and prevention of uneven current sharing between these parallel-connected units.

[0048] In the embodiments of the present application, by establishing a DCR database that includes the correspondence between the state parameter group of the battery pack and the DCR, and using this DCR database to determine the DCR of the battery pack under the current state parameters, the influence of different influencing factors on the DCR of the battery pack is comprehensively considered, and the accuracy of the DCR can be improved.

[0049] The following details the establishment process of the correspondence between multiple state parameter groups and multiple DCRs.

[0050] After determining various state parameters that may affect the DCR of the battery, the value of each state parameter in the DCR test 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 actual applications, a longer charging time range and / or a larger current range can be set.

[0051] Table 1

[0052]

[0053]

[0054] During 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 individually, and a series of DCR tests for different values of this state parameter are carried out.

[0055] For example, taking a fresh battery cell as the test object, 100% SOH, the test environment temperature is 25°C, the charging current is constant at 140A under the charging state, and the DCR of the battery cell under different SOCs is tested under this condition. The values of SOC include 0%, 5%, 10%, 15%, ……, 95%, 100%.

[0056] First, for the DCR test when 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 with a current of 140A for 60s, and record the voltage of the battery cell at multiple moments. For example, as shown in Table 2, when SOC is 0%, the voltage of the battery cell is recorded at 5s intervals within the charging time of 5s - 60s.

[0057] Table 2

[0058] 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 >

[0059] According to Table 2, the DCR of a single battery cell can be calculated for different charging durations. As an example, the DCR of a single battery cell can be calculated using the DCR test principle shown in Figure 5 As shown, after charging a single battery cell with a constant current I for a certain duration ΔT, the DCR of the single battery cell can be determined based on the voltage U, current I, and initial voltage U0 of the single battery cell at the moment after this duration ΔT. Among them, DCR = (U - U0) / I. Figure 5 As shown in

[0060] In Table 2, U0 is the initial voltage, that is, the static voltage. Then, the DCR of the single battery cell at the time of charging for 0 s is DCR 01 , the DCR of the single battery cell at the time of charging for 5 s 02 = (U5 - U0) / I, the DCR of the single battery cell at the time of charging for 10 s 03 = (U 10 - U0) / I, the DCR of the single battery cell at the time of charging for 15 s 04 = (U 15 - U0) / I, the DCR of the single battery cell at the time of charging for 20 s 05 = (U 20 - U0) / I, ……, the DCR of the single battery cell at the time of charging for 55 s 06 = (U 55 - U0) / I, the DCR of the single battery cell at the time of charging for 60 s 07 = (U 60 - U0) / I, where I = 140 A.

[0061] In this way, the corresponding relationship between the charging time and DCR can be obtained as shown in Table 3 under the conditions of meeting 100% SOH, a test ambient temperature of 25 °C, a constant charging current of 140 A in the charging state, and an SOC of 0%.

[0062] Table 3

[0063] [[ID=4Q]] 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 >

[0064] Secondly, adjust the SOC of the single battery cell to 5%, and conduct the test according to the above operation. Similarly, the corresponding relationship between the charging time and DCR can be obtained as shown in Table 3 under the conditions of meeting 100% SOH, a test ambient temperature of 25 °C, a constant charging current of 140 A in the charging state, and an SOC of 5%.

[0065] In sequence, adjust the SOC of each battery cell at intervals of 5% SOC, and perform DCR tests according to the above operations. A DCR mapping table can be obtained under the conditions of 100% SOH, a test environment temperature of 25°C, a constant charging current of 140A in the charging state, SOC values of 0%, 5%, 10%, 15%, …, 95%, 100%, and charging times of 0s, 5s, 15s, …, 60s. For example, the corresponding relationship between the state parameter group composed of charging time and SOC and DCR as shown in Table 4.

[0066] Table 4

[0067]

[0068] In the same way, sequentially change the values of the remaining state parameters such as temperature, current, and SOH, and complete a series of 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 DCR, thereby establishing a multi-dimensional full-life cycle DCR database for the battery.

[0069] This DCR database includes the corresponding relationships between multiple state parameter groups and 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 parameters such as 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 the state parameter group of the battery pack can be found from the DCR database stored in the BMS.

[0070] 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 are used as examples in the form of a mapping table, and the mapping relationship between each state parameter in the state parameter group and DCR is stored in the BMS in the form of a mapping table.

[0071] In one implementation, in step 120, the DCRs in the DCR database that correspond to the state parameter group of the battery pack can be directly determined as the DCRs of the battery pack, so as to simply and quickly obtain the DCRs of the battery pack.

[0072] In another implementation, in step 120, for parameter values between 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 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 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 through the interpolation algorithm.

[0073] 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 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 the 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 can be determined as the DCR of the battery pack.

[0074] Taking SOC as an example, assume that the parameter values of each state parameter in the current state parameter group of the battery pack are as follows: SOH is 100%, the test environment temperature is 25°C, the charging current is constant at 140A during charging, the charging duration is 60s, and the SOC is 8%. If the SOC in the DCR database is at intervals of 5% and includes the DCRs corresponding to SOCs of 0%, 5%, 10%, 15%, ……, 95%, 100%. Then, the SOC values closest to 8% SOC are 5% and 10%, and the DCRs under the conditions of SOH being 100%, the test environment temperature being 25°C, the charging current being constant at 140A during charging, the charging duration being 60s, and the SOC being 5%, and the DCRs under the conditions of SOH being 100%, the test environment temperature being 25°C, the charging current being constant at 140A during charging, the charging duration being 60s, and the SOC being 10% can be found respectively.

[0075] Assume that the values of DCR corresponding to 5% SOC and 10% SOC are DCR 16 and DCR 26 respectively. 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 140 A during charging, the charging duration being 60 s, and the SOC being 8% can be obtained as DCR 16 +(DCR 26 -DCR 16 )*(8% - 5%) / (10% - 5%) = DCR 16 +3(DCR 26 -DCR 16 ) / 5.

[0076] When multiple battery packs are connected in parallel to the grid, since the voltages of multiple battery packs are the same, according to 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 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 an uneven current distribution among multiple battery packs according to the DCR of the multiple parallel-connected battery packs. That is, by detecting the DCR of the multiple parallel-connected battery packs, it is determined whether there is an uneven current distribution among the multiple battery packs, so as to timely detect and prevent the uneven current distribution between the parallel-connected battery packs.

[0077] Optionally, it is possible to determine whether there is an uneven current distribution among multiple battery packs according to the difference between the DCRs of the multiple parallel-connected battery packs. 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. Among them, 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.

[0078] For example, it can be determined that there is an uneven current distribution among multiple battery packs when the ratio of the DCR of the first battery pack to the DCR of the second battery pack among the multiple battery packs is greater than the corresponding DCR threshold; or for another example, it can be determined that there is an 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.

[0079] 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 battery packs, the uneven current distribution among the multiple battery packs can be timely detected.

[0080] As an example, such as Figure 6The detection process of the DCR shown takes the battery pack as an example of a battery cluster. Among them, 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.

[0081] 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.

[0082] In step 102, the parameter values of multiple state parameters in the state parameter group of the battery cluster are obtained.

[0083] For example, the state parameter group includes parameters such as SOC, temperature, current, charge and discharge direction, charge and discharge time, and SOH.

[0084] In step 103, the SBMU determines the DCR of the battery cluster according to the current state parameter group of the battery cluster and the corresponding relationship between multiple state parameter groups and multiple DCRs in the DCR database.

[0085] In step 104, the SBMU determines whether the parameter values of the state parameters in the current state parameter group of the battery cluster are in the DCR database.

[0086] Among them, when the parameter value of the state parameter is included in the DCR database, step 105 is executed; when the parameter value of the state parameter is not included in the DCR database, step 106 is executed.

[0087] In step 105, the SBMU determines the DCR corresponding to the parameter value of the state parameter as the DCR of the battery cluster.

[0088] In step 106, the SBMU selects the value adjacent to the parameter value in the DCR database and calculates the DCR corresponding to the parameter value through an interpolation algorithm, which is used as the DCR of the battery cluster.

[0089] Among them, the SBMU can report the DCR of the corresponding battery cluster to the MBMU.

[0090] In step 107, the MBMU calculates the inter-cluster internal resistance difference according to the DCRs of multiple parallel-connected battery clusters.

[0091] 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.

[0092] In step 108, the MBMU determines whether the difference in internal resistance between clusters DCRmax / DCRmin is greater than a preset DCR threshold, which is denoted as x%, for example, where x is a preset value.

[0093] When the difference in internal resistance between clusters DCRmax / DCRmin is greater than the DCR threshold x%, that is, when DCRmax / DCRmin > x%, step 109 is executed; when the difference in internal resistance 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.

[0094] In step 109, an uneven current sharing strategy is executed.

[0095] 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.

[0096] The above has described in detail the DCR detection method of the embodiments of the present application. Next, in combination with Figure 7 and Figure 8 the DCR detection device of the embodiments of the present application will be described in detail. The technical features described in the method embodiments are applicable to the following device embodiments.

[0097] Figure 7 is a schematic block diagram of the DCR detection device of the embodiments of the present application. As Figure 7 shown, the detection device 200 includes an acquisition module 210 and a processing module 220.

[0098] Among them, the acquisition module 210 is used to obtain a set of state parameters of the battery pack, and this set of state parameters includes at least two state parameters of the battery pack.

[0099] The processing module 220 is used to determine the DCR of the battery pack according to the set of state parameters of the battery pack and the corresponding relationship between a preset set of multiple state parameters and multiple DCRs.

[0100] This set of state parameters includes, for example, at least two of the following state parameters: SOC, temperature, current, charge and discharge direction, charge and discharge time, and SOH of the battery pack, etc.

[0101] This battery pack can be, for example, a battery cluster or an electrical cabinet. This battery cluster or 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.

[0102] In some embodiments, the processing module 220 is specifically configured to determine the DCRs corresponding to the state parameter groups of the battery packs among the multiple DCRs as the DCRs of the battery packs.

[0103] In some embodiments, the state parameter group includes a first state parameter, and the correspondence includes multiple values of the first state parameter corresponding to the multiple DCRs. The processing module 220 is specifically configured to determine, among the multiple values, the first value and the second value that are closest to the parameter value of the first state parameter of the battery pack; 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, based on the interpolation algorithm, the DCR corresponding to the parameter value of the first state parameter of the battery pack 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.

[0104] In some embodiments, the processing module 220 is further configured to determine whether there is uneven current sharing among the multiple parallel-connected battery packs according to the DCRs of the multiple battery packs.

[0105] In some embodiments, the processing module 220 is specifically configured to determine 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.

[0106] 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.

[0107] The present application further provides an energy storage system, such as Figure 1 the energy storage system 1 shown in. The energy storage system 1 includes multiple 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 packs.

[0108] The present application further 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.

[0109] The present application further provides a DCR detection device 300. The detection device 300 can be, for example, a BMS, including an SBMU and / or an MBMU. As Figure 8As 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.

[0110] Optionally, as Figure 8 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.

[0111] It should be understood that the processor in the embodiments of the present application may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method embodiments can be completed by the integrated logic circuit in the hardware of the processor or by instructions in software form. 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 a 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 random access memory, flash memory, read-only memory, programmable read-only memory or electrically erasable programmable memory, register, etc. This storage medium is located in the memory, and the processor reads the information in the memory and combines its hardware to complete the steps of the above method.

[0112] 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.

[0113] 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 combination should also fall within the protection scope of the present application.

[0114] In the embodiments of the present application, the magnitudes of the sequence numbers of the various steps do not mean the order of execution. The order of execution of the various steps should be determined according to their functions and internal logics, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0115] Those of ordinary skill in the art can realize that the units and algorithm steps of each example 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. Professional technicians 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.

[0116] 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 between 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.

[0117] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiments of the present application.

[0118] 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 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 set of state parameters of the battery pack, where the set of state parameters includes at least two state parameters of the battery pack; Determining the DC resistance of the battery pack according to the set of state parameters of the battery pack and a preset correspondence between multiple sets of state parameters and multiple DC resistances.

2. The detection method according to claim 1, wherein The set of state parameters includes at least two 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 according to the set of state parameters of the battery pack and a preset correspondence between multiple sets of state parameters and multiple DC resistances includes: Determining the DC resistance corresponding to the set of state parameters of the battery pack among the multiple DC resistances as the DC resistance of the battery pack.

4. The detection method according to claim 1 or 2, characterized in that, The set of state parameters includes a first state parameter, and the correspondence includes multiple values of the first state parameter corresponding to the multiple DC resistances. The determining the DC resistance of the battery pack according to the set of state parameters of the battery pack and a preset correspondence between multiple sets of state parameters and multiple 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 among the multiple 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 correspondence; Determining the DC resistance corresponding to the parameter value of the first state parameter of the battery pack 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.

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

6. The detection method according to claim 5, wherein The determining whether there is uneven current sharing among the multiple battery packs according to the DC resistances 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 DC resistance of a first battery pack and the DC resistance of a second battery pack among the multiple battery packs is greater than a preset DC resistance threshold, 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.

7. The detection method according to claim 5 or 6, 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.

8. A detecting device for DC resistance, characterized in that, The detection device includes: An acquisition module for obtaining a set of state parameters of the battery pack, where the set of state parameters includes at least two state parameters of the battery pack; A processing module for determining the DC resistance of the battery pack according to the set of state parameters of the battery pack and a preset correspondence between multiple sets of state parameters and multiple DC resistances.

9. The detection device according to claim 8, wherein The state parameter group includes at least two 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.

10. The detection device according to claim 8 or 9, characterized in that, Specifically, the processing module is configured to determine the DC resistance corresponding to the state parameter group of the battery pack among the plurality of DC resistances as the DC resistance of the battery pack.

11. The detection device according to claim 8 or 9, characterized in that, 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 DC resistances. Specifically, the processing module is configured to determine, among the plurality of values, a first value and a second value that are closest to the parameter value of the first state parameter of the battery pack; determine, according to the first value, the second value, and the correspondence, the DC resistance corresponding to the first value and the DC resistance corresponding to the second value; determine, based on an interpolation algorithm, the DC resistance corresponding to the parameter value of the first state parameter of the battery pack 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.

12. The detection device according to any one of claims 8 to 11, characterized in that, The processing module is further configured to determine whether there is uneven current sharing among the plurality of battery packs according to the DC resistances of the plurality of parallel-connected battery packs.

13. The detection device according to claim 12, characterized in that, Specifically, the processing module is configured to determine that there is uneven current sharing among the plurality of battery packs when the ratio between the DC resistance of a first battery pack and the DC resistance of a second battery pack among the plurality of battery packs is greater than a preset DC resistance threshold, where the first battery pack is the battery pack with the largest DC resistance among the plurality of battery packs, and the second battery pack is the battery pack with the smallest DC resistance among the plurality of battery packs.

14. The detection device according to claim 12 or 13, characterized in that, The battery pack is 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.

15. An energy storage system, characterized in that, including: a plurality of parallel-connected battery packs; and the DC resistance detection device according to any one of claims 8 to 14, where the detection device is configured to detect the DC resistance of the battery pack.

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