Current distribution method and analog circuit

Abstract

A current distribution method and analog circuit are provided that can ensure that battery clusters with different capacities quickly reach equilibrium during operation and improve the stability and reliability of a battery energy storage system. The method includes the steps of: determining a distribution ratio limit interval to be set for each battery cluster based on the total number of battery clusters connected in parallel in the battery energy storage system (S101); determining a target current distribution ratio to be set for each battery cluster based on battery cluster parameters (S102); and distributing current to each battery cluster according to the target current distribution ratio (S103), wherein the target current distribution ratio is within the distribution ratio limit interval, and the battery cluster parameters include at least one of the current remaining capacity of the battery cluster, the capacity setting threshold, and the distribution ratio limit interval.

Description

[Technical Field]

[0001] The present disclosure relates to the technical field of circuits, and more particularly to current sharing methods and analog circuits. (CROSS-REFERENCE TO RELATED APPLICATIONS) This disclosure claims priority to a Chinese application filed with the China Patent Office on November 1, 2023, bearing application number 202311444824.3 and entitled "Current Distribution Method and Analog Circuit," the entire contents of which are incorporated herein by reference. [Background technology]

[0002] A battery energy storage system consists of multiple battery clusters connected in parallel. Overcharging or over-discharging of the battery clusters can cause irreversible capacity loss, and overcharging can pose safety hazards such as fire or explosion. To prevent overcharging or over-discharging of the battery clusters, it is common for a DC / DC converter in the battery energy storage system to precisely control the charge and discharge current of the battery clusters.

[0003] However, in the current current control algorithm, the current distribution ratio set for each battery cluster is calculated only taking into account the difference in the state of charge or the difference in battery capacity, making it difficult for the battery energy storage system to quickly reach an equilibrium state during the charge and discharge process. Furthermore, when the difference in the initial state of charge is excessively large, the difference in the current distribution ratio obtained by the current current control algorithm to make the state of charge of each battery cluster consistent may be relatively large. When the difference in the current distribution ratio is relatively large, fluctuations caused by external factors in the battery energy storage system are likely to cause overload of the battery energy storage system. Summary of the Invention [Problem to be solved by the invention]

[0004] In view of the above, the present disclosure aims to provide a current distribution method and an analog circuit that can ensure that battery clusters with different capacities quickly reach equilibrium during operation, thereby achieving the effects of improving the stability and reliability of the battery energy storage system.

[0005] In a first aspect, an embodiment of the present disclosure provides a current distribution method, the method including: determining a distribution ratio limit interval to be set for each battery cluster based on a total number of battery clusters connected in parallel in a battery energy storage system; determining a current distribution target ratio to be set for each battery cluster based on battery cluster parameters; and distributing current to each battery cluster according to the current distribution target ratio, wherein the current distribution target ratio is within the distribution ratio limit interval, and the battery cluster parameters include at least one of a current remaining capacity of the battery cluster, a capacity setting threshold, and the distribution ratio limit interval.

[0006] In one embodiment of the present disclosure, the step of determining the distribution ratio restriction section to be set for each battery cluster based on the total number of multiple battery clusters connected in parallel in the battery energy storage system includes a step of determining the distribution ratio restriction section to be set for each battery cluster based on the total number of multiple battery clusters connected in parallel in the battery energy storage system when the system parameters of the battery energy storage system do not satisfy the conditions for equal current distribution.

[0007] In one embodiment of the present disclosure, the method further includes a step of determining a current equalization distribution ratio to be set for each battery cluster based on the total number of the battery clusters when the system parameters of the battery energy storage system satisfy the condition of current equalization distribution, and a step of distributing current to each battery cluster according to the current equalization distribution ratio.

[0008] In one embodiment of the present disclosure, the conditions for current equal distribution include any one of the following: the battery energy storage system is in a stopped working state; the DC / DC converter in the battery energy storage system is in a fault state; the minimum state of charge of the battery energy storage system during discharging is less than a first predetermined ratio; and the maximum state of charge of the battery energy storage system during charging is greater than or equal to a second predetermined ratio, wherein the first predetermined ratio is smaller than the second predetermined ratio, and a state of charge difference representing the difference between the maximum state of charge and the minimum state of charge of all battery clusters currently connected to the DC bus is smaller than a predetermined difference threshold.

[0009] In one embodiment of the present disclosure, the step of determining a distribution ratio limit section to be set for each battery cluster based on the total number of battery clusters connected in parallel in the battery energy storage system includes the steps of obtaining the total number of battery clusters connected in parallel in the battery energy storage system and an overload limit ratio of the battery energy storage system, and determining a distribution ratio limit upper limit value and a distribution ratio limit lower limit value of the battery energy storage system based on the overload limit ratio, thereby determining a distribution ratio limit section to be set for each battery cluster, wherein the overload limit ratio represents a predetermined ratio by which the current of a battery cluster is allowed to exceed a rated current range during charging or discharging.

[0010] In one embodiment of the present disclosure, the step of determining the upper limit distribution ratio limit value and the lower limit distribution ratio limit value of the battery energy storage system based on the overload limit ratio includes the steps of determining the upper limit distribution ratio limit total value and the lower limit distribution ratio limit total value of the battery energy storage system based on the overload limit ratio, and determining the upper limit distribution ratio limit value and the lower limit distribution ratio limit value to be set for each battery cluster using the ratio between the upper limit distribution ratio limit total value and the lower limit distribution ratio limit total value and the total number of battery clusters.

[0011] In one embodiment of the present disclosure, the battery cluster parameters include a current remaining capacity of the battery cluster and a capacity setting threshold representing a charging state at which each battery cluster in the battery energy storage system converges to a consensus the fastest, and the step of determining the target current distribution ratio to be set for each battery cluster based on the battery cluster parameters includes: determining a first current distribution ratio to be adjusted to be set for each battery cluster based on the current remaining capacity of each battery cluster and the capacity setting threshold; and determining the target current distribution ratio based on whether the first current distribution ratio to be adjusted is within the distribution ratio limit interval.

[0012] In one embodiment of the present disclosure, the step of determining the target current distribution ratio based on whether the first current distribution ratio to be adjusted is within the distribution ratio restricted section includes a step of determining, when it is detected that the first current distribution ratio to be adjusted set for each battery cluster is within the distribution ratio restricted section, the first current distribution ratio to be adjusted of each battery cluster that is within the distribution ratio restricted section as the target current distribution ratio of the corresponding battery cluster.

[0013] In one embodiment of the present disclosure, the step of determining the target current distribution ratio based on whether the first current distribution ratio to be adjusted is within the distribution ratio restricted section further includes the step of adjusting the capacity setting threshold when it is detected that the first current distribution ratio to be set for a battery cluster does not fall within the distribution ratio restricted section, and resetting the first current distribution ratio to be set for each battery cluster based on the current remaining capacity of each battery cluster and the adjusted capacity setting threshold until the reset first current distribution ratio to be adjusted for each battery cluster is within the distribution ratio restricted section, and determining the first current distribution ratio to be adjusted of each battery cluster that is within the distribution ratio restricted section as the target current distribution ratio of the corresponding battery cluster.

[0014] In one embodiment of the present disclosure, the step of determining the target current distribution ratio to be set for each battery cluster based on the battery cluster parameters further includes the steps of: when it is detected that a first current distribution ratio to be reset for a battery cluster exists, where the adjusted capacity setting threshold does not fall within the capacity adjustment limit range and does not fall within the distribution ratio restriction section; determining a second current distribution ratio to be set for each battery cluster based on the current remaining capacity of each battery cluster; and determining the target current distribution ratio based on whether the second current distribution ratio to be adjusted is within the distribution ratio restriction section.

[0015] In one embodiment of the present disclosure, the step of determining the target current distribution ratio based on whether the second current distribution ratio to be adjusted is within the distribution ratio restricted section includes a step of determining, when it is detected that the second current distribution ratio to be adjusted set for each battery cluster is within the distribution ratio restricted section, the second current distribution ratio to be adjusted of each battery cluster that is within the distribution ratio restricted section as the target current distribution ratio of the corresponding battery cluster.

[0016] In one embodiment of the present disclosure, the battery cluster parameters include a distribution ratio limit section, and the distribution ratio limit section includes a distribution ratio limit upper limit value and a distribution ratio limit lower limit value, and the step of determining the target current distribution ratio based on whether a second adjustment-target current distribution ratio is within the distribution ratio limit section includes, when it is detected that the second adjustment-target current distribution ratio set for a battery cluster does not fall within the distribution ratio limit section, determining the number of first battery clusters that are battery clusters in which the second adjustment-target current distribution ratio is greater than the distribution ratio limit upper limit value and determining the target current distribution ratio based on whether a second adjustment-target current distribution ratio is within the distribution ratio limit section. determining the number of second battery clusters that are battery clusters smaller than the distribution ratio limit lower limit value; determining a distribution ratio adjustment value for adjusting a second adjustment-target current distribution ratio that does not fall within the distribution ratio limit section to the closest distribution ratio limit upper limit value or distribution ratio limit lower limit value, and obtaining a distribution ratio adjustment total value corresponding to all battery clusters whose second adjustment-target current distribution ratios do not fall within the distribution ratio limit section; and determining a current distribution target ratio based on the magnitude relationship between the distribution ratio adjustment total value and a predetermined distribution ratio adjustment threshold value.

[0017] In one embodiment of the present disclosure, the distribution ratio adjustment value for adjusting the second current distribution ratio to be adjusted from a value smaller than the distribution ratio limit lower limit to the distribution ratio limit lower limit is a negative value, and the distribution ratio adjustment value for adjusting the second current distribution ratio to be adjusted from a value larger than the distribution ratio limit upper limit to the distribution ratio limit upper limit is a positive value.

[0018] In one embodiment of the present disclosure, the step of determining the target current distribution ratio based on the magnitude relationship between the total distribution ratio adjustment value and a predetermined distribution ratio adjustment threshold includes, when the total distribution ratio adjustment value is greater than the predetermined distribution ratio adjustment threshold, determining the target current distribution ratio to be set for battery clusters whose second adjustment-target current distribution ratio does not fall within the distribution ratio restriction section based on the distribution ratio restriction lower limit value, the total distribution ratio adjustment value, and the number of second battery clusters, and determining the target current distribution ratio to be set for battery clusters whose second adjustment-target current distribution ratio is within the distribution ratio restriction section based on the current remaining capacity of the battery clusters.

[0019] In one embodiment of the present disclosure, the step of determining the target current distribution ratio to be set to a battery cluster whose second adjustment-target current distribution ratio does not fall within the distribution ratio restriction section, based on the distribution ratio restriction lower limit value, the distribution ratio adjustment total value, and the number of second battery clusters, includes the steps of determining a distribution ratio adjustment average value, based on a ratio between the distribution ratio adjustment total value and the number of second battery clusters, and determining the target current distribution ratio to be set to a battery cluster whose second adjustment-target current distribution ratio does not fall within the distribution ratio restriction section, based on the sum of the distribution ratio restriction lower limit value and the distribution ratio adjustment average value.

[0020] In one embodiment of the present disclosure, the step of determining the target current distribution ratio based on the magnitude relationship between the distribution ratio adjustment total value and a predetermined distribution ratio adjustment threshold further includes, when the distribution ratio adjustment total value is equal to or less than the predetermined distribution ratio adjustment threshold, determining a target current distribution ratio to be set for a battery cluster whose second adjustment-target current distribution ratio does not fall within the distribution ratio restriction section based on the distribution ratio restriction upper limit value, the distribution ratio adjustment total value, and the number of the first battery clusters, and determining a target current distribution ratio to be set for a battery cluster whose second adjustment-target current distribution ratio is within the distribution ratio restriction section based on a current remaining capacity of the battery cluster.

[0021] In one embodiment of the present disclosure, the step of determining the target current distribution ratio based on the magnitude relationship between the distribution ratio adjustment total value and the predetermined distribution ratio adjustment threshold further includes: when it is detected that the target current distribution ratio to be set for a battery cluster whose second adjustment-target current distribution ratio does not fall within the distribution ratio restriction interval does not fall within the distribution ratio restriction interval, recalculating the corresponding distribution ratio adjustment total values ​​for all battery clusters whose target current distribution ratios do not fall within the distribution ratio restriction interval; and checking the magnitude relationship between the recalculated distribution ratio adjustment total value and the predetermined distribution ratio adjustment threshold, and repeating the following process until the new target current distribution ratios reset for each battery cluster whose target current distribution ratio does not fall within the distribution ratio restriction interval are within the distribution ratio restriction interval.

[0022] The processing includes the steps of: when the recalculated distribution ratio adjustment total value is greater than a predetermined distribution ratio adjustment threshold, re-determining a new current distribution target ratio to be set to a battery cluster whose current distribution target ratio does not fall within the distribution ratio restriction section, based on the distribution ratio limit lower limit value, the recalculated distribution ratio adjustment total value, and the number of second battery clusters; and when the recalculated distribution ratio adjustment total value is equal to or less than the predetermined distribution ratio adjustment threshold, re-determining a new current distribution target ratio to be set to a battery cluster whose current distribution target ratio does not fall within the distribution ratio restriction section, based on the distribution ratio limit upper limit value, the recalculated distribution ratio adjustment total value, and the number of first battery clusters.

[0023] In a second aspect, an embodiment of the present disclosure further provides an analog circuit, which applies the current distribution method described above, and includes a main relay, a first relay, a second relay, a third relay, a controlled current source, and a controlled voltage source, wherein the controlled current source and the first relay are connected in series to form a first control branch circuit, the controlled voltage source and the second relay are connected in series to form a second control branch circuit, the first control branch circuit and the second control branch circuit are connected in parallel and further connected in series with the main relay, and the third relay and the controlled current source are connected in parallel.

[0024] The current distribution method and analog circuit according to the embodiment of the present disclosure first determine a distribution ratio limit range to be set for each battery cluster based on the total number of battery clusters connected in parallel in a battery energy storage system, then determine a target current distribution ratio to be set for each battery cluster based on battery cluster parameters, and finally distribute current to each battery cluster according to the target current distribution ratio, where the target current distribution ratio is within the distribution ratio limit range and the battery cluster parameters include at least one of the current remaining capacity of the battery cluster, the capacity setting threshold, and the distribution ratio limit range. [Effects of the Invention]

[0025] In contrast to conventional current control algorithms that calculate the current distribution ratio for each battery cluster based only on differences in the state of charge (SOC) or battery capacity, the embodiment of the present disclosure first limits the distribution ratio limit range for each battery cluster. This limits the target current distribution ratio for each battery cluster, regardless of whether the initial SOC difference between the battery clusters is excessive. This prevents excessive differences in the target current distribution ratios for each battery cluster due to excessive differences in the initial SOC. As a result, the SOCs of the battery clusters can be matched more quickly, and the problem of external fluctuations in the battery energy storage system easily causing an overload in the battery energy storage system when the current distribution ratio difference is large can be prevented. The target current distribution ratio for each battery cluster is then determined based on battery cluster parameters. The battery cluster parameters include at least one of the current remaining capacity of the battery cluster, the capacity setting threshold, and the distribution ratio limit range. Using the above method, the DC / DC converter in the battery energy storage system can accurately distribute current to each battery cluster according to the target current distribution ratio. By using the limit ratio within the distribution ratio limit range as the target current distribution ratio, the DC / DC converter can charge and discharge at the allowable limit current, ensuring that battery clusters with different capacities quickly reach equilibrium during operation and achieving the effect of improving the stability and reliability of the battery energy storage system.

[0026] In order to make the above objects, features and advantages of the present disclosure more apparent, preferred embodiments will be described in detail below with reference to the drawings. [Brief explanation of the drawings]

[0027] In order to more clearly explain the technical solutions of the embodiments in the present disclosure, the drawings necessary for explaining the embodiments will be briefly described below. The drawings described only illustrate some embodiments of the present disclosure and do not limit the scope. Those skilled in the art can obtain other related drawings based on these drawings without using inventive abilities. [Figure 1] 1 is a flowchart of a current sharing method according to an embodiment of the present disclosure. [Figure 2] 10 is a flowchart of another current sharing method according to an embodiment of the present disclosure. [Figure 3] FIG. 2 is a schematic diagram of an analog circuit in a first state according to an embodiment of the present disclosure. [Figure 4] FIG. 2 is a schematic diagram of an analog circuit in a second state according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0028] In order to make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings used in the embodiments of the present disclosure. Of course, the described embodiments are only some embodiments of the present disclosure, and do not necessarily represent all embodiments. The components in the embodiments of the present disclosure shown in the drawings can be arranged and designed in various ways. Therefore, the following detailed description of the embodiments of the present disclosure shown in the drawings only illustrates selected embodiments of the present disclosure and does not limit the scope of the present disclosure to be protected. All other embodiments that can be obtained by those skilled in the art based on the embodiments of the present disclosure without using their inventive abilities fall within the scope of protection of the present disclosure.

[0029] As used herein, the terms "a," "an," "the," and "said" mean that there are one or more elements / components, etc.; the terms "comprise" and "have" indicate an open inclusion, meaning that other elements / components, etc. may be present in addition to the listed elements / components, etc.; and the terms "first," "second," etc. are used merely as notations and do not quantitatively limit the subject matter.

[0030] In the embodiments of the present disclosure, "at least one" means one or more, and "multiple" means two or more. "And / or" represents a relationship between related objects and indicates that three relationships may exist. For example, A and / or B can represent three situations: A exists independently, A and B exist simultaneously, and B exists independently. The symbol " / " usually indicates that the related objects before and after it have an "or" relationship. "Comprising A, B, and / or C" means including any one, two, or three of A, B, and C.

[0031] In the embodiments of the present disclosure, "B corresponding to A," "B corresponding to A," "A and B correspond," or "B and A correspond" means that B and A are related to each other and B can be identified based on A. However, identifying B based on A does not mean identifying B based on A alone, but may also mean identifying B based on A and / or other information.

[0032] Furthermore, the described embodiments are only some of the embodiments of the present disclosure, and not all of the embodiments. The components in the embodiments of the present disclosure shown in the drawings can be arranged and designed in various ways. Therefore, the following detailed description of the embodiments of the present disclosure shown in the drawings only illustrates selected embodiments of the present disclosure and does not limit the scope of the present disclosure to be protected. All other embodiments that can be obtained by a person skilled in the art based on the embodiments of the present disclosure without using inventive ability fall within the scope of protection of the present disclosure.

[0033] First, a battery energy storage system consists of multiple battery clusters connected in parallel. Overcharging or over-discharging of the battery clusters can cause irreversible capacity loss. Moreover, overcharging can pose safety hazards such as fire or explosion. To prevent overcharging or over-discharging of the battery clusters, it is common for a DC / DC converter in the battery energy storage system to precisely control the charge and discharge current of the battery clusters.

[0034] However, in the current current control algorithm, the set current distribution ratio of each battery cluster is calculated only taking into account the difference in the state of charge or the difference in battery capacity, so at least one charging process, one discharging process, one cycle process, or multiple cycle processes are required to reach an equilibrium state, making it difficult for the battery energy storage system to quickly reach an equilibrium state during the charging and discharging process.

[0035] Furthermore, if the difference in the initial charge state is too large, such that some are in an overloaded state and some are in a stopped state, the influence of the temperature difference due to the excessive current difference will also be relatively large, and the inconsistency of the battery cluster will be magnified during long-term operation, which will have a significant impact on the overall lifespan, aging, utilization rate, discharge depth, etc. of the battery energy storage system.

[0036] In order to match the state of charge of each battery cluster, the current current control algorithm may result in a relatively large difference in the current distribution ratio, and when the difference in the current distribution ratio is relatively large, fluctuations caused by external factors in the battery energy storage system are likely to cause overload problems in the battery energy storage system.

[0037] In view of the above, the embodiments of the present disclosure provide a current distribution method that can ensure that battery clusters with different capacities quickly reach equilibrium during operation, thereby achieving the effect of improving the stability and reliability of the battery energy storage system.

[0038] 1 is a flowchart of a current distribution method according to an embodiment of the present disclosure. As shown in FIG. 1, the current distribution method according to an embodiment of the present disclosure includes the following steps:

[0039] Step S101: Determine a distribution ratio limit section to be set for each battery cluster based on the total number of battery clusters connected in parallel in the battery energy storage system.

[0040] Step S102: Determine a target current distribution ratio to be set for each battery cluster based on the battery cluster parameters, where the target current distribution ratio is within a distribution ratio limit range, and the battery cluster parameters include at least one of the current remaining capacity of the battery cluster, the capacity setting threshold, and the distribution ratio limit range.

[0041] Step S103: Distribute current to each battery cluster according to the target current distribution ratio.

[0042] In step S101, the battery energy storage system includes multiple battery clusters connected in parallel and a DC / DC converter. The battery cluster includes multiple battery cells connected in series or parallel. Even with precise capacity settings, each battery cell has a different initial capacity. During use, the battery cells in a battery cluster may experience inconsistent capacity degradation due to differences in the temperature and manufacturing process of the battery cells. The DC / DC converter converts a direct current (DC) power source into a DC (or near-DC) power source of a different voltage and includes many high-speed switching diodes. The high-speed switching diodes have a fast switching speed and can complete switching operations in a short time, thereby improving the response speed of the circuit. Therefore, the current distribution method shown in FIG. 1 is implemented in the DC / DC converter, which enables precise control of the charge / discharge current of the battery cluster and prevents the battery cluster from being overcharged or overdischarged.

[0043] The total number of battery clusters refers to the total number of all battery clusters in the battery energy storage system. Based on the total number of battery clusters, not only the current equal distribution ratio set for each battery cluster but also the distribution ratio limit range set for each battery cluster can be determined.

[0044] Specifically, step S101 includes the following steps:

[0045] Step S1011: Obtain the total number of battery clusters connected in parallel in the battery energy storage system and the overload limit ratio of the battery energy storage system, where the overload limit ratio represents a predetermined ratio at which the current of the battery cluster can exceed the rated current range during charging or discharging.

[0046] Here, overload means that the battery energy storage system can operate beyond the rated current range even in some abnormal state. An abnormal state means that the battery energy storage system operates without a portion of the cluster and outputs a constant power / current. The overload limit ratio represents the predetermined ratio by which the current of the battery cluster can exceed the rated current range during charging or discharging, i.e., the predetermined ratio by which the current during charging of the battery cluster can exceed a first predetermined current value, or the predetermined ratio by which the current during discharging of the battery cluster can fall below a second predetermined current value, where the second predetermined current value is smaller than the first predetermined current value, and the range consisting of the first and second predetermined current values ​​is the rated current range.

[0047] Exemplarily, the overload limit ratio ranges between 0 and 1, and specifically, the overload limit ratio may be 0.1.

[0048] Step S1012: Determine the upper and lower limit values ​​of the distribution ratio limit of the battery energy storage system according to the overload limit ratio, thereby determining the distribution ratio limit section to be set for each battery cluster.

[0049] Specifically, the distribution ratio limit upper limit value and the distribution ratio limit lower limit value are determined as two end points of the distribution ratio limit interval.

[0050] Illustratively, step S1012 specifically includes the following steps:

[0051] Step S1012a: Determine the upper limit total value and the lower limit total value of the distribution ratio limit of the battery energy storage system according to the overload limit ratio.

[0052] Here, since the overload limit ratio is between 0 and 1, the distribution ratio limit upper limit total value is the sum of 1 and the overload limit ratio, and the distribution ratio limit lower limit total value is the difference between 1 and the overload limit ratio.

[0053] Step S1012b: Using the ratio of each of the upper and lower limit values ​​of the distribution ratio restriction to the total number of battery clusters, the upper and lower limit values ​​of the distribution ratio restriction to be set for each battery cluster are determined.

[0054] Here, the distribution ratio limiting section of each battery cluster is the same.

[0055] For example, let the total number of battery clusters be n, the overload limit ratio be limit, and the upper limit of the distribution ratio limit be I pct_max , the distribution ratio limit lower limit is I pct_min When defined as above, the upper limit of the distribution ratio I pct_max and the lower limit of the distribution ratio I pct_min The calculation formula is as follows:

[0056]

number

[0057]

number

[0058] As an example, depending on the actual configuration parameters of the battery cluster, the limit can be set to 0.1, and therefore, The result is TIFF2025540550000004.tif31170.

[0059] The embodiment of the present disclosure adjusts the overload limit ratio in real time according to the actual working conditions of the battery cluster, and can flexibly set the upper and lower limit values ​​of the distribution ratio limit. Within this distribution ratio limit range, current can be distributed according to the target current distribution ratio set for each battery cluster. The ability to specify the range of the target current distribution ratio further improves the stability and reliability of the battery energy storage system.

[0060] In step S102, the battery cluster parameter refers to a parameter related to the current distribution of the battery cluster. This parameter may be an attribute feature of the battery cluster, such as the current remaining capacity of the battery cluster. Alternatively, this parameter may be a preset value based on the attribute feature of the battery cluster. The preset value can be adjusted in real time and is applicable to all battery clusters, for example, each battery cluster corresponds to the same capacity setting threshold. Alternatively, this parameter may be a value calculated based on the attribute feature of the battery cluster, such as a distribution ratio limit range calculated based on the total number of battery clusters and the overload limit ratio.

[0061] Here, the target current distribution ratio set for each battery cluster is determined based on the battery cluster parameters, and this target current distribution ratio is within the distribution ratio limit range. That is, the target current distribution ratio set for each battery cluster can be accurately determined based on the battery cluster parameters. In this way, current is distributed to each battery cluster according to this target current distribution ratio, so that battery clusters with different capacities can quickly reach balance during operation.

[0062] Furthermore, if the difference in the state of charge of each battery cluster is too large, the target current distribution ratio of each battery cluster will differ, but by keeping the difference in the target current distribution ratio within the distribution ratio limit range, the state of charge of each battery cluster can be made to match more quickly and overload of the battery energy storage system due to external fluctuations can be minimized, thereby achieving balanced management and safe use and further extending the life of the battery clusters in the battery energy storage system.

[0063] In a preferred embodiment, the battery cluster parameters include a current remaining capacity of the battery cluster and a capacity setting threshold. The current remaining capacity refers to the maximum chargeable capacity or maximum dischargeable capacity of the battery cluster in the current working state, and the capacity setting threshold refers to the charge state that each battery cluster in the battery energy storage system can match most quickly. For example, the capacity setting threshold may be the minimum value among the current remaining capacities of the multiple battery clusters.

[0064] Here, a capacity adjustment limit range is preset for the capacity setting threshold, and the capacity setting threshold cannot be exceeded when adjusting the capacity adjustment limit range. Specifically, when multiple battery clusters in the battery energy storage system are in a discharging or charging process, the capacity adjustment limit range is from 0 to the capacity setting threshold.

[0065] Step S102 specifically includes the following steps:

[0066] Step 1021: Determine a first current distribution ratio to be adjusted to be set for each battery cluster according to the current remaining capacity and the capacity setting threshold of each battery cluster.

[0067] Specifically, the difference between the current remaining capacity of each battery cluster and the capacity setting threshold is calculated, the sum of the corresponding capacity differences of all battery clusters is calculated, and for each battery cluster, the ratio of the corresponding capacity difference of the corresponding battery cluster to the sum of the capacity differences is calculated, and this ratio is determined as the first adjustment target current distribution ratio.

[0068] For example, the first current distribution ratio to be adjusted of the i-th battery cluster is I 1i,pct , capacity setting threshold is min_cap, current remaining capacity is cap i , where the total number of battery clusters is defined as n, the first current distribution ratio to be adjusted for the i-th battery cluster I 1i,pct The calculation formula is as follows:

[0069]

number

[0070] The above formula can be used to calculate the corresponding first adjustment target current distribution ratio for each battery cluster, and this first adjustment target current distribution ratio can achieve the purpose of quickly distributing current to the battery cluster.

[0071] Step 1022: Determine the target current distribution ratio based on whether the first current distribution ratio to be adjusted is within the distribution ratio limit interval.

[0072] Step 1022 specifically includes the following steps:

[0073] Step 1022a: If it is detected that the first current distribution ratio to be adjusted to be set for each battery cluster is within the distribution ratio limit section, the first current distribution ratio to be adjusted of each battery cluster within the distribution ratio limit section is determined as the target current distribution ratio of each corresponding battery cluster.

[0074] Here, if the corresponding first adjustment target current distribution ratios of each battery cluster are all within the distribution ratio limit section, the currently calculated first adjustment target current distribution ratio is determined as the target current distribution ratio, and current is distributed to the battery cluster according to this first adjustment target current distribution ratio.

[0075] Step 1022b: If it is detected that the first current distribution ratio to be adjusted to be set for the battery cluster does not fall within the distribution ratio restriction interval, adjust the capacity setting threshold, and re-determine the first current distribution ratio to be adjusted to be set for each battery cluster based on the current remaining capacity of each battery cluster and the adjusted capacity setting threshold until the re-determined first current distribution ratio to be adjusted for each battery cluster falls within the distribution ratio restriction interval, and determine the first current distribution ratio to be adjusted of each battery cluster that falls within the distribution ratio restriction interval as the target current distribution ratio of each corresponding battery cluster.

[0076] That is, when a first current distribution ratio to be adjusted corresponding to a battery cluster is detected as not falling within the distribution ratio limit range, the capacity setting threshold may be adjusted. For example, the capacity setting threshold may be reduced. Then, the first current distribution ratio to be adjusted set for each battery cluster is recalculated using the calculation formula for the first current distribution ratio to be adjusted in step 1021 until the capacity setting threshold is adjusted to the minimum value of the capacity adjustment limit range, such as 0. If it is detected that the first current distribution ratios to be adjusted corresponding to each battery cluster are all within the distribution ratio limit range under the condition that the capacity setting threshold is within the capacity adjustment limit range, the currently determined first current distribution ratio to be adjusted is determined as the target current distribution ratio.

[0077] Step 1023: If it is detected that the adjusted capacity setting threshold does not fall within the capacity adjustment limit range and does not fall within the distribution ratio restriction section, and a first current distribution ratio to be reset to the battery cluster exists, a second current distribution ratio to be adjusted is determined to be set to each battery cluster based on the current remaining capacity of each battery cluster.

[0078] Here, the current remaining capacities of all battery clusters are summed to obtain the sum of the current remaining capacities, and for each battery cluster, the ratio between the corresponding current remaining capacity of the battery cluster and the sum of the current remaining capacities is calculated, and this ratio is determined as the second current distribution ratio to be adjusted.

[0079] For example, the second current distribution ratio to be adjusted of the i-th battery cluster is I 2i,pctThen, the second current distribution ratio to be adjusted for the i-th battery cluster I 2i,pct The calculation formula is as follows:

[0080]

number

[0081] The above formula can be used to calculate the corresponding second current distribution ratio to be adjusted for each battery cluster, and this second current distribution ratio to be adjusted can achieve the purpose of quickly distributing current to the battery cluster.

[0082] Step 1024: Determine the target current distribution ratio based on whether the second current distribution ratio to be adjusted is within the distribution ratio limit interval.

[0083] Step 1024 specifically includes the following steps:

[0084] Step 1024a: If it is detected that the second current distribution ratio to be adjusted set for each battery cluster is within the distribution ratio limit range, the second current distribution ratio to be adjusted of each battery cluster within the distribution ratio limit range is determined as the target current distribution ratio of each corresponding battery cluster.

[0085] Here, if the corresponding second current distribution ratios to be adjusted of each battery cluster are all within the distribution ratio limit range, the currently calculated second current distribution ratio to be adjusted is determined as the target current distribution ratio, and current can be distributed to the battery cluster according to this second current distribution ratio to be adjusted.

[0086] Step 1024b: If it is detected that the second adjustment target current distribution ratio to be set for the battery cluster does not fall within the distribution ratio limit range, the number of first battery clusters, which are battery clusters whose second adjustment target current distribution ratio is greater than the distribution ratio limit upper limit value, and the number of second battery clusters, which are battery clusters whose second adjustment target current distribution ratio is smaller than the distribution ratio limit lower limit value, are determined.

[0087] The battery cluster parameters include a distribution ratio limit range, and the distribution ratio limit range includes an upper limit value and a lower limit value of the distribution ratio limit, and the number of first battery clusters can be determined based on the upper limit value of the distribution ratio limit, and the number of second battery clusters can be determined based on the lower limit value of the distribution ratio limit.

[0088] Step 1024c: Determine a distribution ratio adjustment value for adjusting the second current distribution ratio to the closest distribution ratio limit upper limit value or distribution ratio limit lower limit value from the second current distribution ratio to be adjusted that does not fall within the distribution ratio limit section, and obtain the corresponding distribution ratio adjustment total value of all battery clusters whose second current distribution ratio to be adjusted does not fall within the distribution ratio limit section.

[0089] The distribution ratio adjustment value for adjusting the second adjustment target current distribution ratio, which is smaller than the distribution ratio limit lower limit value, to the distribution ratio limit lower limit value is a negative value, and the distribution ratio adjustment value for adjusting the second adjustment target current distribution ratio, which is larger than the distribution ratio limit upper limit value, to the distribution ratio limit upper limit value is a positive value.

[0090] Here, the difference between the second current distribution ratio to be adjusted and its closest upper or lower limit of distribution ratio restriction is calculated, and this difference is used as the distribution ratio adjustment value. Specifically, this difference can be either positive or negative. A distribution ratio adjustment value obtained by calculating the difference between a second current distribution ratio to be adjusted that is smaller than the lower limit of distribution ratio restriction and the lower limit of distribution ratio restriction is negative, while a distribution ratio adjustment value obtained by calculating the difference between a second current distribution ratio to be adjusted that is larger than the upper limit of distribution ratio restriction and the upper limit of distribution ratio restriction is positive. The total distribution ratio adjustment value is obtained by summing the corresponding distribution ratio adjustment values ​​of all battery clusters whose second current distribution ratio to be adjusted does not fall within the distribution ratio restriction range. Here, since the distribution ratio adjustment value can be either positive or negative, the calculated total distribution ratio adjustment value can be either positive or negative.

[0091] Step 1025: Determine the target current distribution ratio based on the magnitude relationship between the distribution ratio adjustment total value and the predetermined distribution ratio adjustment threshold value.

[0092] Step 1025 specifically includes the following steps:

[0093] Step 1025a: If the distribution ratio adjustment total value is greater than the predetermined distribution ratio adjustment threshold, determine the target current distribution ratio to be set for the battery clusters whose second adjustment target current distribution ratio does not fall within the distribution ratio restriction section based on the distribution ratio restriction lower limit value, the distribution ratio adjustment total value, and the number of second battery clusters, and determine the target current distribution ratio to be set for the battery clusters whose second adjustment target current distribution ratio falls within the distribution ratio restriction section based on the current remaining capacity of the battery clusters.

[0094] For example, the predetermined distribution ratio adjustment threshold may be 0. Regarding the corresponding second current distribution ratio to be adjusted of each battery cluster calculated in step 1023, the corresponding second current distribution ratio to be adjusted of some or all battery clusters may not fall within the distribution ratio restriction section. Therefore, for battery clusters whose second current distribution ratio to be adjusted does not fall within the distribution ratio restriction section, the target current distribution ratio is calculated using the new calculation method in step 1025, and for battery clusters whose second current distribution ratio to be adjusted is within the distribution ratio restriction section, the target current distribution ratio is still calculated using the calculation method in step 1023.

[0095] Here, if the distribution ratio adjustment total value is equal to or less than the predetermined distribution ratio adjustment threshold, for a battery cluster whose second adjustment target current distribution ratio does not fall within the distribution ratio restriction section, the target current distribution ratio is determined using the following calculation method.

[0096] The distribution ratio adjustment average value is determined based on the ratio between the distribution ratio adjustment total value and the number of second battery clusters. The current distribution target ratio to be set for battery clusters whose second adjustment target current distribution ratio does not fall within the distribution ratio restriction section is determined based on the sum of the distribution ratio restriction lower limit value and the distribution ratio adjustment average value.

[0097] For example, the current distribution target ratio of the i-th battery cluster is I 32i,pct , where n2 is the number of second battery clusters and Vol is the total distribution ratio adjustment value, the current distribution target ratio I32i,pct The calculation formula is as follows:

[0098]

number

[0099] Step 1025b: If the distribution ratio adjustment total value is equal to or less than the predetermined distribution ratio adjustment threshold, determine the target current distribution ratio to be set for the battery clusters whose second adjustment target current distribution ratio does not fall within the distribution ratio restriction section based on the distribution ratio restriction upper limit value, the distribution ratio adjustment total value, and the number of first battery clusters, and determine the target current distribution ratio to be set for the battery clusters whose second adjustment target current distribution ratio falls within the distribution ratio restriction section based on the current remaining capacity of the battery clusters.

[0100] Here, if the distribution ratio adjustment total value is equal to or less than the predetermined distribution ratio adjustment threshold, for a battery cluster whose second adjustment target current distribution ratio does not fall within the distribution ratio restriction section, the target current distribution ratio is determined using the following calculation method.

[0101] The distribution ratio adjustment average value is determined based on the ratio between the distribution ratio adjustment total value and the number of first battery clusters. The current distribution target ratio to be set for battery clusters whose second current distribution ratio is not within the distribution ratio restriction section is determined based on the sum of the distribution ratio restriction upper limit value and the distribution ratio adjustment average value.

[0102] For example, the current distribution target ratio of the i-th battery cluster is I 31i,pct , where n1 is the number of the first battery cluster and Vol is the total distribution ratio adjustment value, the current distribution target ratio I 31i,pct The calculation formula is as follows:

[0103]

number

[0104] If the second current distribution ratio to be adjusted does not fall within the distribution ratio restriction section, the current distribution target ratio is calculated directly in step 1025a or step 1025b based on the magnitude relationship between the distribution ratio adjustment total value and the predetermined distribution ratio adjustment threshold value.

[0105] Step 1025c: If it is detected that the target current distribution ratio to be set for the battery cluster whose second adjustment target current distribution ratio does not fall within the distribution ratio restriction section does not fall within the distribution ratio restriction section, the corresponding distribution ratio adjustment total values ​​of all battery clusters whose target current distribution ratios do not fall within the distribution ratio restriction section are recalculated.

[0106] The magnitude relationship between the recalculated distribution ratio adjustment total value and the predetermined distribution ratio adjustment threshold is checked, and step 1025a and / or step 1025b are repeated until the new current distribution target ratio reset for each battery cluster whose current distribution target ratio does not fall within the distribution ratio restriction range falls within the distribution ratio restriction range.

[0107] The current distribution target ratio finally determined in step 1025c is certainly within the distribution ratio limit interval, and therefore no further calculation by other methods is necessary.

[0108] According to the above method, different calculation methods can be used to determine the target current distribution ratio under different parameter conditions, so that the current can be accurately distributed to each battery cluster according to the corresponding target current distribution ratio, and the battery clusters with different capacities can be quickly balanced during operation.

[0109] In step S103, current is distributed to each battery cluster according to the target current distribution ratio determined in step S102. This allows the difference in the initial state of charge of each battery cluster to be kept within the corresponding limit range of the distribution ratio limit section, regardless of whether it is excessive or not. In addition, since the current can be distributed quickly at the maximum current output capacity of the distribution ratio limit section, each battery cluster in the battery energy storage system can reach equilibrium within the current allowable range as quickly as possible.

[0110] 2 is a flowchart of another current distribution method according to an embodiment of the present disclosure. As shown in FIG. 2, the current distribution method according to an embodiment of the present disclosure includes the following steps:

[0111] Step S201: If the system parameters of the battery energy storage system do not satisfy the conditions for equal current distribution, determine the distribution ratio limit section to be set for each battery cluster based on the total number of battery clusters connected in parallel in the battery energy storage system.

[0112] Step S202: Determine a target current distribution ratio to be set for each battery cluster based on the battery cluster parameters. The target current distribution ratio is within a distribution ratio limit range, and the battery cluster parameters include at least one of the current remaining capacity of the battery cluster, the capacity setting threshold, and the distribution ratio limit range. Distribute current to each battery cluster according to the target current distribution ratio.

[0113] Step S203: If the system parameters of the battery energy storage system satisfy the condition of current equalization, determine the current equalization ratio to be set for each battery cluster according to the total number of battery clusters, and distribute current to each battery cluster according to the current equalization ratio.

[0114] For an explanation of step S202, please refer to step S102, and the explanation will be omitted here.

[0115] In step S201, the conditions for current equal sharing include any one of the following: the battery energy storage system is in a stopped working state, the DC / DC converter in the battery energy storage system is in a fault state, the minimum state of charge of the battery energy storage system when discharging is less than a first predetermined ratio, and the maximum state of charge of the battery energy storage system when charging is greater than or equal to a second predetermined ratio. The first predetermined ratio is smaller than the second predetermined ratio, and the state of charge difference, which represents the difference between the maximum state of charge and the minimum state of charge of all battery clusters currently connected to the DC bus, is smaller than a predetermined difference threshold.

[0116] The Battery Management System (BMS) collects statistics on the total number of parallel-connected battery clusters, the initial charge state of each battery cluster, the current remaining capacity of each battery cluster, and the system work state, including the stopped work state, the charging work state, and the discharging work state. Based on the collected data, the BMS determines whether the system parameters of the battery energy storage system meet the requirements for equal current distribution.

[0117] Illustratively, to prevent the capacity difference between the current remaining capacities of each battery cluster in the battery energy storage system from becoming too large, the predetermined difference threshold is selected to be a relatively small value, such as 1%, for example.

[0118] Here, if the system parameters of the battery energy storage system do not satisfy the above-mentioned conditions for equal current distribution, the distribution ratio limit section to be set for each battery cluster is determined based on the total number of battery clusters connected in parallel in the battery energy storage system. For the specific implementation method, please refer to step S101, and the description will be omitted here.

[0119] Furthermore, in step S203, if the system parameters of the battery energy storage system satisfy the condition for current equalization, determine the current equalization ratio to be set for each battery cluster based on the total number of battery clusters, and distribute current to each battery cluster according to the current equalization ratio.

[0120] That is, when the battery energy storage system is in a stopped working state, or when the DC / DC converter in the battery energy storage system is in a fault state, or when the minimum state of charge of the battery energy storage system during discharge is less than the first predetermined ratio, or when the maximum state of charge of the battery energy storage system during charging is greater than or equal to the second predetermined ratio, the first predetermined ratio is smaller than the second predetermined ratio, for example, the first predetermined ratio is 10% and the second predetermined ratio is 90%, and the difference in state of charge representing the difference between the maximum state of charge and the minimum state of charge of all battery clusters currently connected to the DC bus is smaller than the predetermined difference threshold, and in this case, the current equal distribution ratio to be set for each battery cluster is determined directly based on the total number of battery clusters.

[0121] Illustratively, the current equalization ratio is determined by the following formula:

[0122]

number

[0123] Here, n represents the total number of battery clusters.

[0124] By determining the current equal distribution ratio set for each battery cluster in the above manner, the current can be distributed to each battery cluster quickly, and is relatively simple and convenient.

[0125] In an embodiment of the present disclosure, first, a distribution ratio limit range is set for each battery cluster. This limits the target current distribution ratio set for each battery cluster, regardless of whether the initial state-of-charge (SOC) difference between the battery clusters is excessive. This prevents excessive differences in the target current distribution ratios of the battery clusters due to excessive differences in the initial state-of-charge (SOC). As a result, the SOCs of the battery clusters can be matched more quickly, and the problem of external fluctuations in the battery energy storage system easily causing overload when the current distribution ratio difference is large can be prevented. Then, the target current distribution ratio set for each battery cluster is determined based on battery cluster parameters. The battery cluster parameters include at least one of the current remaining capacity of the battery cluster, the capacity setting threshold, and the distribution ratio limit range. Using the above method, the DC / DC converter in the battery energy storage system can accurately distribute current to each battery cluster according to the target current distribution ratio. By using the limit ratio within the distribution ratio limit range as the target current distribution ratio, the DC / DC converter can charge and discharge at the allowable limit current, ensuring that battery clusters with different capacities quickly reach equilibrium during operation and achieving the effect of improving the stability and reliability of the battery energy storage system.

[0126] In practice, DC / DC converters in related technical solutions contain many high-speed switching diodes, making it difficult to obtain desired results in a short time using simulation methods, resulting in slow simulation speeds. In particular, series DC / DC converters in battery energy storage systems have complex circuit configurations, making it relatively slow to directly verify the execution of current distribution methods, making it difficult to obtain final verification results in a short time. Furthermore, because the internal resistance of ideal current sources is infinite and the internal resistance of ideal voltage sources is infinitesimal, ideal current sources cannot be open-circuited and ideal voltage sources cannot be short-circuited, resulting in circuit modeling errors and computational difficulties.

[0127] In view of this, an embodiment of the present disclosure provides an analog circuit that applies the current distribution method as shown in Fig. 1 or 2. As shown in Fig. 3 or 4, the analog circuit includes a main relay 401, a first relay 402, a second relay 403, a third relay 404, a controlled current source 405, and a controlled voltage source 406, wherein the controlled current source 405 and the first relay 402 are connected in series to form a first control branch circuit, the controlled voltage source 406 and the second relay 403 are connected in series to form a second control branch circuit, the first control branch circuit and the second control branch circuit are connected in parallel and further connected in series with the main relay 401, and the third relay 404 and the controlled current source 405 are connected in parallel.

[0128] Here, the above analog circuit is equivalent to a battery cluster and a DC / DC converter connected in series in a battery energy storage system.

[0129] The embodiments of the present disclosure use ideal current sources, ideal voltage sources, and relays to achieve voltage and current decoupling control. This avoids the simulation problems associated with infinitesimal internal resistances of ideal power supplies. By applying the current distribution algorithm shown in FIG. 1 or 2 to the analog circuit, the series DC / DC converter can charge and discharge at the maximum allowable current. Furthermore, when the difference in the state of charge (SOC) is excessive, the difference in the target current distribution ratios of each battery cluster is prevented from becoming excessive. This allows the SOCs of each battery cluster to match as quickly as possible, minimizing overload of the battery energy storage system due to external fluctuations. This also avoids the problem of the prior art, where the complex circuit configuration of a series DC / DC converter makes it difficult to verify the implementation of the current distribution method of the embodiments of the present disclosure and obtain final verification results in a short time.

[0130] As shown in FIG. 3, the analog circuit is in a first state, and at this time, voltage regulation can be performed without load as follows.

[0131] The DC / DC converter has a voltage regulation capability of 10V to 20V. When the main relay Ks is turned off, the analog circuit equivalent to the series DC / DC converter is a series controlled voltage source with a default of 10V. Relay Ks1 connected in series with controlled current source 405 is in the same state as the main relay Ks (off), and relay Ks2 connected in series with controlled voltage source 406 is in the opposite state to the main relay Ks (on). Therefore, the analog circuit equivalent to the series DC / DC converter is such that controlled voltage source 406 is connected in series between the main relay Ks and the positive terminal of the battery, and the internal voltage of the main relay Ks is the sum of the battery voltage and the voltage of controlled voltage source 406. Because the internal resistance of the ideal current source is infinite, it cannot open, thus shorting out relay Ks3, and the state of relay Ks3 is the opposite state to the state of the main relay Ks.

[0132] As shown in FIG. 4, the analog circuit is in a second state, in which case current regulation can be performed as follows.

[0133] When the voltage meets the closing condition, the main relay Ks is turned on, and then relay Ks1 matches the main relay Ks (turns on), while relays Ks2 and Ks3 are turned off. At this time, the analog circuit equivalent to the series DC / DC converter is connected in series with a controlled current source 405. A current sharing algorithm is used to precisely control the current of each battery cluster and achieve balance between the clusters. At the same time, a controlled voltage source 406 must be connected in parallel to the positive and negative poles of the DC bus, and its value is the minimum terminal voltage of all currently integrated clusters plus 20V. When Δsoc<10%, the terminal voltage difference between clusters is less than 10V. If the bus voltage is the minimum terminal voltage of the cluster plus 20V, the voltage regulation capability of the series DC / DC converter within 20V can meet the voltage regulation requirements of all integrated clusters. The voltage of the integrated series DC / DC converter in the analog circuit is the voltage difference between the bus voltage and the terminal voltage, and is automatically regulated by an ideal current source.

[0134] The embodiments of the present disclosure use an analog circuit to solve the high-speed calculation requirements of the switching diodes of a real series DC / DC converter. The implementation of an ideal power supply allows the external characteristics of the real series DC / DC converter to be reflected in the analog circuit. The series-parallel connection of the ideal power supply and the relay solves the problem of the ideal current source being unable to open and the ideal voltage source being unable to short. Furthermore, the analog circuit can improve simulation speed and speed up verification of the feasibility of the current distribution method. The current distribution method verified by the analog circuit can improve the stability and reliability of the battery energy storage system when used.

[0135] The above examples are merely specific embodiments for illustrating the technical solutions of the present disclosure and are not intended to limit the present disclosure, and therefore the scope of protection of the present disclosure is not limited thereto. Although the above examples have been used to describe the present disclosure in detail, those skilled in the art may improve or modify the technical solutions described in the above examples within the technical scope disclosed in the present disclosure, or may make equivalent substitutions for some of the technical features therein. The essence of the relevant technical solutions of these improvements, modifications, or substitutions does not deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure, and all fall within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be dictated by the claims. [Industrial Applicability]

[0136] The present disclosure provides a current distribution method and an analog circuit, the method including: determining a distribution ratio limit range to be set for each battery cluster based on the total number of parallel-connected battery clusters in a battery energy storage system; determining a target current distribution ratio to be set for each battery cluster based on battery cluster parameters; and distributing current to each battery cluster according to the target current distribution ratio, where the target current distribution ratio is within the distribution ratio limit range, and the battery cluster parameters include at least one of the current remaining capacity of the battery cluster, the capacity setting threshold, and the distribution ratio limit range. This can ensure that battery clusters with different capacities quickly reach equilibrium during operation, thereby improving the stability and reliability of the battery energy storage system.

[0137] The current distribution method and analog circuit according to the present disclosure are reproducible and applicable to various industrial applications, for example, in the field of circuit technology.

Claims

1. determining a distribution ratio limit section to be set for each battery cluster based on the total number of battery clusters connected in parallel in the battery energy storage system; determining a target current distribution ratio to be set for each battery cluster based on the battery cluster parameters; and distributing current to each battery cluster according to the current distribution target ratio; The target current distribution ratio is within the distribution ratio limit section, and the battery cluster parameters include at least one of a current remaining capacity of the battery cluster, a capacity setting threshold, and the distribution ratio limit section. A current distribution method comprising:

2. The step of determining a distribution ratio limit section to be set for each battery cluster based on the total number of battery clusters connected in parallel in the battery energy storage system includes: If the system parameters of the battery energy storage system do not satisfy the condition for equal current distribution, determining a distribution ratio limit section to be set for each battery cluster based on the total number of battery clusters connected in parallel in the battery energy storage system.

2. The current sharing method according to claim 1.

3. If the system parameters of the battery energy storage system satisfy the condition of current equalization, determining a current equalization ratio to be set for each battery cluster according to the total number of the battery clusters; and distributing the current to each battery cluster according to the current equal distribution ratio.

3. The current sharing method according to claim 2.

4. The conditions for the current equalization include any one of the following: the battery energy storage system is in a stopped working state; a DC / DC converter in the battery energy storage system is in a fault state; the minimum state of charge of the battery energy storage system when discharging is less than a first predetermined ratio; and the maximum state of charge of the battery energy storage system when charging is greater than or equal to a second predetermined ratio, wherein the first predetermined ratio is smaller than the second predetermined ratio, and a difference in state of charge representing a difference between the maximum state of charge and the minimum state of charge of all battery clusters currently connected to the DC bus is smaller than a predetermined difference threshold.

4. The current distribution method according to claim 2 or 3.

5. The step of determining a distribution ratio limit section to be set for each battery cluster based on the total number of battery clusters connected in parallel in the battery energy storage system includes: Obtaining a total number of a plurality of parallel-connected battery clusters in a battery energy storage system and an overload limit ratio of the battery energy storage system; determining a distribution ratio limit upper limit value and a distribution ratio limit lower limit value of the battery energy storage system based on the overload limit ratio, thereby determining a distribution ratio limit section to be set for each battery cluster; The overload limit ratio represents a predetermined ratio by which the current of the battery cluster can exceed the rated current range during charging or discharging.

2. The current sharing method according to claim 1.

6. determining a distribution ratio limit upper limit value and a distribution ratio limit lower limit value of the battery energy storage system according to the overload limit ratio, determining a distribution ratio limit upper limit total value and a distribution ratio limit lower limit total value of the battery energy storage system according to the overload limit ratio; determining a distribution ratio limit upper limit value and a distribution ratio limit lower limit value to be set for each battery cluster using a ratio between the total number of the battery clusters and each of the total upper limit value and the total lower limit value of the distribution ratio limit.

6. The current sharing method according to claim 5.

7. The battery cluster parameters include a current remaining capacity of the battery cluster and a capacity setting threshold representing a state of charge that each battery cluster in the battery energy storage system can match most quickly; The step of determining a current distribution target ratio to be set for each battery cluster based on the battery cluster parameters includes: determining a first adjustment target current distribution ratio to be set for each battery cluster based on the current remaining capacity of each battery cluster and the capacity setting threshold; determining a target current distribution ratio based on whether the first adjustment target current distribution ratio is within the distribution ratio limit section; 2. The current sharing method according to claim 1.

8. determining a target current distribution ratio based on whether a first adjustment target current distribution ratio is within the distribution ratio limit section, When it is detected that a first current distribution ratio to be adjusted set for each battery cluster is within the distribution ratio limit section, the first current distribution ratio to be adjusted of each battery cluster within the distribution ratio limit section is determined as a target current distribution ratio for each corresponding battery cluster.

8. The current sharing method according to claim 7.

9. determining a target current distribution ratio based on whether a first adjustment target current distribution ratio is within the distribution ratio limit section, If it is detected that the first current distribution ratio to be adjusted set for each battery cluster does not fall within the distribution ratio limit section, the method further includes a step of adjusting the capacity setting threshold, and re-determining the first current distribution ratio to be adjusted set for each battery cluster based on the current remaining capacity of each battery cluster and the adjusted capacity setting threshold until the reset first current distribution ratio to be adjusted for each battery cluster falls within the distribution ratio limit section, and determining the first current distribution ratio to be adjusted of each battery cluster within the distribution ratio limit section as the target current distribution ratio of each corresponding battery cluster.

8. The current sharing method according to claim 7.

10. The step of determining a current distribution target ratio to be set for each battery cluster based on the battery cluster parameters includes: When detecting that there is a first current distribution ratio to be adjusted that has been reset to a battery cluster, the adjusted capacity setting threshold does not fall within the capacity adjustment limit range and does not fall within the distribution ratio restriction section, determining a second current distribution ratio to be adjusted that is to be set to each battery cluster based on the current remaining capacity of each battery cluster; determining a target current distribution ratio based on whether the second current distribution ratio to be adjusted is within the distribution ratio limit section; 8. The current sharing method according to claim 7.

11. determining the target current distribution ratio based on whether the second current distribution ratio to be adjusted is within the distribution ratio limit section, When it is detected that the second current distribution ratio to be adjusted set for each battery cluster is within the distribution ratio limit section, the second current distribution ratio to be adjusted of each battery cluster within the distribution ratio limit section is determined as the target current distribution ratio of the corresponding battery cluster.

11. The current sharing method according to claim 10.

12. the battery cluster parameter includes a distribution ratio limit section, the distribution ratio limit section including a distribution ratio limit upper limit value and a distribution ratio limit lower limit value; determining the target current distribution ratio based on whether the second current distribution ratio to be adjusted is within the distribution ratio limit section, when it is detected that a second current distribution ratio to be adjusted set to a battery cluster does not fall within the distribution ratio limit section, determining the number of first battery clusters that are battery clusters in which the second current distribution ratio to be adjusted is greater than the distribution ratio limit upper limit value, and the number of second battery clusters that are battery clusters in which the second current distribution ratio to be adjusted is smaller than the distribution ratio limit lower limit value; determining a distribution ratio adjustment value for adjusting a second current distribution ratio to be adjusted to a closest upper or lower limit of the distribution ratio restriction value from a second current distribution ratio to be adjusted that does not fall within the distribution ratio restriction range, and obtaining a corresponding total distribution ratio adjustment value of all battery clusters whose second current distribution ratio to be adjusted does not fall within the distribution ratio restriction range; determining a target current distribution ratio based on a magnitude relationship between the distribution ratio adjustment total value and a predetermined distribution ratio adjustment threshold value.

11. The current sharing method according to claim 10.

13. The distribution ratio adjustment value for adjusting the second adjustment-target current distribution ratio, which is smaller than the distribution ratio limit lower limit value, to the distribution ratio limit lower limit value is a negative value, and the distribution ratio adjustment value for adjusting the second adjustment-target current distribution ratio, which is larger than the distribution ratio limit upper limit value, to the distribution ratio limit upper limit value is a positive value.

13. The current sharing method of claim 12.

14. The step of determining the current distribution target ratio based on the magnitude relationship between the distribution ratio adjustment total value and the predetermined distribution ratio adjustment threshold value includes: When the total distribution ratio adjustment value is greater than a predetermined distribution ratio adjustment threshold, determining a target current distribution ratio to be set to a battery cluster whose second adjustment target current distribution ratio does not fall within the distribution ratio limit section based on the distribution ratio limit lower limit value, the distribution ratio adjustment total value, and the number of the second battery clusters, and determining a target current distribution ratio to be set to a battery cluster whose second adjustment target current distribution ratio falls within the distribution ratio limit section based on a current remaining capacity of the battery cluster.

14. The current sharing method of claim 13.

15. determining a target current distribution ratio to be set for a battery cluster whose second adjustment target current distribution ratio does not fall within the distribution ratio restriction section based on the distribution ratio restriction lower limit value, the distribution ratio adjustment total value, and the number of second battery clusters, determining a distribution ratio adjustment average value based on the ratio of the distribution ratio adjustment total value to the number of the second battery clusters; determining a target current distribution ratio to be set for a battery cluster whose second adjustment target current distribution ratio does not fall within the distribution ratio restriction section based on the sum of the distribution ratio restriction lower limit value and the distribution ratio adjustment average value.

15. The current sharing method of claim 14.

16. The step of determining the current distribution target ratio based on the magnitude relationship between the distribution ratio adjustment total value and the predetermined distribution ratio adjustment threshold value includes: When the distribution ratio adjustment total value is equal to or less than a predetermined distribution ratio adjustment threshold, the method further includes determining a target current distribution ratio to be set to a battery cluster whose second adjustment target current distribution ratio does not fall within the distribution ratio limit section based on the distribution ratio limit upper limit value, the distribution ratio adjustment total value, and the number of the first battery clusters, and determining a target current distribution ratio to be set to a battery cluster whose second adjustment target current distribution ratio falls within the distribution ratio limit section based on a current remaining capacity of the battery cluster.

14. The current sharing method of claim 13.

17. The step of determining the current distribution target ratio based on the magnitude relationship between the distribution ratio adjustment total value and the predetermined distribution ratio adjustment threshold value includes: when detecting that the target current distribution ratio set for a battery cluster whose second adjustment target current distribution ratio does not fall within the distribution ratio restriction section does not fall within the distribution ratio restriction section, recalculating the corresponding distribution ratio adjustment total value of all battery clusters whose target current distribution ratios do not fall within the distribution ratio restriction section; checking whether the recalculated distribution ratio adjustment total value is larger or smaller than a predetermined distribution ratio adjustment threshold value, and repeating the following process until a new current distribution target ratio reset for each battery cluster whose current distribution target ratio does not fall within the distribution ratio restriction section falls within the distribution ratio restriction section; The process comprises: If the recalculated distribution ratio adjustment total value is greater than a predetermined distribution ratio adjustment threshold, re-determining a new current distribution target ratio to be set to a battery cluster whose current distribution target ratio does not fall within the distribution ratio limit section based on the distribution ratio limit lower limit value, the recalculated distribution ratio adjustment total value, and the number of the second battery clusters; and when the recalculated distribution ratio adjustment total value is equal to or less than a predetermined distribution ratio adjustment threshold, re-determining a new current distribution target ratio to be set to a battery cluster whose current distribution target ratio does not fall within the distribution ratio limit section, based on the distribution ratio limit upper limit value, the recalculated distribution ratio adjustment total value, and the number of the first battery clusters.

14. The current sharing method of claim 13.

18. An analog circuit to which the current distribution method according to any one of claims 1 to 17 is applied, a main relay, a first relay, a second relay, a third relay, a controlled current source, and a controlled voltage source; The control current source and the first relay are connected in series to form a first control branch circuit, the control voltage source and the second relay are connected in series to form a second control branch circuit, the first control branch circuit and the second control branch circuit are connected in parallel and further connected in series with the main relay, and the third relay and the control current source are connected in parallel.

1. An analog circuit comprising:

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