Current distribution method and analog circuit

Abstract

The invention provides a current distribution method and an analog circuit, and the method comprises the steps: determining a distribution proportion constraint interval set for each battery cluster according to the total number of a plurality of battery clusters connected in parallel in a battery energy storage system, and determining a current distribution target proportion set for each battery cluster according to a battery cluster parameter, the current distribution target proportion is within the distribution proportion constraint interval, and the battery cluster parameters comprise at least one of the following items: the current residual capacity of the battery cluster, a capacity setting critical value and the distribution proportion constraint interval, and distributing current for each battery cluster according to the current distribution target proportion. According to the invention, it can be ensured that the battery clusters with different capacities are rapidly balanced in the operation process, and the stability and reliability of the battery energy storage system are improved.

Description

Technical Field

[0001] The present application relates to the field of circuit technology, and in particular to a current distribution method and an analog circuit. Background Art

[0002] The battery energy storage system consists of multiple battery clusters connected in parallel. During the overcharging or overdischarging of the battery cluster, irreversible capacity decay will occur, and overcharging will also bring safety hazards such as combustion or even explosion. In order to avoid overcharging or overdischarging of the battery cluster, the direct current converter (DC / DC) in the battery energy storage system is often used to accurately control the charging and discharging current of the battery cluster.

[0003] However, in the current current control algorithm, only the difference in charge state or only the difference in battery capacity is considered to calculate the current distribution ratio set for each battery cluster, which makes it difficult for the battery energy storage system to quickly reach a balanced state during the charging and discharging process; and when the initial charge state difference is too large, in order to make the charge state of each battery cluster consistent, the current control algorithm may obtain a current distribution ratio with a large difference, and the oscillation caused by the outside of the battery energy storage system is likely to cause the battery energy storage system to overload when the current distribution ratio difference is large. Summary of the invention

[0004] In view of this, the purpose of the present application is to provide a current distribution method and an analog circuit, which can ensure that battery clusters of different capacities can quickly reach equilibrium during operation, thereby increasing the stability and reliability of the battery energy storage system.

[0005] In a first aspect, an embodiment of the present application provides a current distribution method, the method comprising:

[0006] Determine an allocation ratio constraint interval set for each battery cluster according to the total number of battery clusters connected in parallel in the battery energy storage system;

[0007] Determine a current distribution target ratio set for each battery cluster according to a battery cluster parameter; wherein the current distribution target ratio is within the distribution ratio constraint interval, and the battery cluster parameter includes at least one of the following items: a current remaining capacity of the battery cluster, a capacity setting critical value, and the distribution ratio constraint interval;

[0008] Current is distributed to each battery cluster according to the current distribution target ratio.

[0009] In an optional embodiment of the present application, the allocation ratio constraint interval set for each battery cluster is determined according to the total number of battery clusters of the plurality of battery clusters connected in parallel in the battery energy storage system, including:

[0010] When the system parameters of the battery energy storage system do not satisfy the current balancing condition, determining the allocation ratio constraint interval set for each battery cluster according to the total number of battery clusters of the multiple battery clusters connected in parallel in the battery energy storage system;

[0011] In an optional embodiment of the present application, the method further includes:

[0012] When the system parameters of the battery energy storage system meet the current sharing condition, determine the current sharing ratio set for each battery cluster according to the total number of battery clusters;

[0013] The current is distributed to each battery cluster according to the current sharing ratio.

[0014] In an optional embodiment of the present application, the current sharing condition includes one of the following items: the battery energy storage system is in a static working condition, the 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 discharge is not greater than a first preset ratio, the maximum state of charge of the battery energy storage system during charging is not less than a second preset ratio, the first preset ratio is less than the second preset ratio, the state of charge difference is less than a preset difference threshold, and the state of charge difference 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.

[0015] In an optional embodiment of the present application, the allocation ratio constraint interval set for each battery cluster is determined according to the total number of battery clusters of the plurality of battery clusters connected in parallel in the battery energy storage system, including:

[0016] Obtaining a total number of battery clusters of a plurality of battery clusters connected in parallel in a battery energy storage system and an overload constraint ratio of the battery energy storage system, wherein the overload constraint ratio represents a preset ratio of a current of the battery cluster exceeding a rated current range during charging or discharging;

[0017] According to the overload constraint ratio, an upper limit and a lower limit of an allocation ratio constraint of the battery energy storage system are determined to determine an allocation ratio constraint interval set for each battery cluster.

[0018] In an optional embodiment of the present application, determining an upper limit and a lower limit of an allocation ratio constraint of the battery energy storage system according to the overload constraint ratio includes:

[0019] Determine, according to the overload constraint ratio, a total value of an upper limit constraint of an allocation ratio of the battery energy storage system and a total value of a lower limit constraint of an allocation ratio;

[0020] The upper and lower limits of the allocation ratio constraints set for each battery cluster are determined by using the ratios of the total value of the allocation ratio constraint upper limits and the total value of the allocation ratio constraint lower limits to the total number of battery clusters.

[0021] In an optional embodiment of the present application, the battery cluster parameter includes the current remaining capacity of the battery cluster and a capacity setting critical value; wherein the capacity setting critical value represents the fastest convergence of each battery cluster in the battery energy storage system to a consistent state of charge;

[0022] The step of determining the current distribution target ratio set for each battery cluster according to the battery cluster parameters includes:

[0023] Determining a first current distribution ratio to be adjusted for each battery cluster according to the current remaining capacity of each battery cluster and the capacity setting critical value;

[0024] The current distribution target ratio is determined according to whether the first current distribution ratio to be adjusted is within the distribution ratio constraint interval.

[0025] In an optional embodiment of the present application, determining the current distribution target ratio according to whether the first current distribution ratio to be adjusted is within the distribution ratio constraint interval includes:

[0026] If it is detected that the first current distribution ratio to be adjusted set for each battery cluster is within the distribution ratio constraint interval, the first current distribution ratio to be adjusted for each battery cluster within the distribution ratio constraint interval is determined as the current distribution target ratio of each corresponding battery cluster.

[0027] In an optional embodiment of the present application, determining the current distribution target ratio according to whether the first current distribution ratio to be adjusted is within the distribution ratio constraint interval further includes:

[0028] If it is detected that the first current distribution ratio to be adjusted set for the battery cluster is not within the distribution ratio constraint interval, the capacity setting critical value is adjusted, and the first current distribution ratio to be adjusted set for each battery cluster is re-determined based on the current remaining capacity of each battery cluster and the adjusted capacity setting critical value, until the first current distribution ratio to be adjusted set for each battery cluster is within the distribution ratio constraint interval, and the first current distribution ratio to be adjusted for each battery cluster within the distribution ratio constraint interval is determined to be the corresponding current distribution target ratio for each battery cluster.

[0029] In an optional embodiment of the present application, the determining of the current distribution target ratio set for each battery cluster according to the battery cluster parameters further includes:

[0030] If it is detected that the adjusted capacity setting critical value is not within the capacity adjustment limit range, and there is a first current allocation ratio to be adjusted that is re-set for the battery cluster that is not within the allocation ratio constraint interval, then determine the second current allocation ratio to be adjusted that is set for each battery cluster according to the current remaining capacity of each battery cluster;

[0031] The current distribution target ratio is determined according to whether the second current distribution ratio to be adjusted is within the distribution ratio constraint interval.

[0032] In an optional embodiment of the present application, determining the current distribution target ratio according to whether the second current distribution ratio to be adjusted is within the distribution ratio constraint interval includes:

[0033] If it is detected that the second current distribution ratio to be adjusted set for each battery cluster is within the distribution ratio constraint interval, the second current distribution ratio to be adjusted for each battery cluster within the distribution ratio constraint interval is determined as the corresponding current distribution target ratio for each battery cluster.

[0034] In an optional embodiment of the present application, the battery cluster parameter includes an allocation ratio constraint interval, and the allocation ratio constraint interval includes an allocation ratio constraint upper limit and an allocation ratio constraint lower limit;

[0035] The determining of the current distribution target ratio according to whether the second current distribution ratio to be adjusted is within the distribution ratio constraint interval further includes:

[0036] If it is detected that the second current allocation ratio to be adjusted set for the battery cluster is not within the allocation ratio constraint interval, then respectively determining the number of first battery clusters corresponding to battery clusters whose second current allocation ratio to be adjusted is greater than the upper limit of the allocation ratio constraint and the number of second battery clusters corresponding to battery clusters whose second current allocation ratio to be adjusted is less than the lower limit of the allocation ratio constraint;

[0037] Determine an allocation ratio adjustment value of adjusting the second current allocation ratio to be adjusted that is not within the allocation ratio constraint interval to the closest allocation ratio constraint upper limit or allocation ratio constraint lower limit, so as to obtain a total allocation ratio adjustment value corresponding to all battery clusters whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval;

[0038] The current distribution target ratio is determined according to the magnitude relationship between the total distribution ratio adjustment value and the preset distribution ratio adjustment threshold.

[0039] In an optional embodiment of the present application, the allocation ratio adjustment value of the second current allocation ratio to be adjusted which is less than the allocation ratio constraint lower limit to the allocation ratio constraint lower limit is a negative value, and the allocation ratio adjustment value of the second current allocation ratio to be adjusted which is greater than the allocation ratio constraint upper limit to the allocation ratio constraint upper limit is a positive value.

[0040] In an optional embodiment of the present application, determining the current distribution target ratio according to the magnitude relationship between the total distribution ratio adjustment value and a preset distribution ratio adjustment threshold value includes:

[0041] If the total value of the allocation ratio adjustment is greater than the preset allocation ratio adjustment threshold, the current allocation target ratio is set for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval according to the allocation ratio constraint lower limit, the total value of the allocation ratio adjustment and the second number of battery clusters, and the current allocation target ratio is set for the battery cluster whose second current allocation ratio to be adjusted is within the allocation ratio constraint interval according to the current remaining capacity of the battery cluster.

[0042] In an optional embodiment of the present application, determining, according to the allocation ratio constraint lower limit, the allocation ratio adjustment total value, and the second number of battery clusters, that the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval sets a current allocation target ratio, includes:

[0043] Determine an allocation ratio adjustment mean value by using a ratio between the allocation ratio adjustment total value and the number of the second battery clusters;

[0044] By using the sum of the allocation ratio constraint lower limit and the allocation ratio adjustment mean value, it is determined to set a current allocation target ratio for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval.

[0045] In an optional embodiment of the present application, determining the current distribution target ratio according to the magnitude relationship between the total distribution ratio adjustment value and the preset distribution ratio adjustment threshold value further includes:

[0046] If the total allocation ratio adjustment value is less than or equal to a preset allocation ratio adjustment threshold, then the current allocation target ratio is set for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval according to the allocation ratio constraint upper limit, the allocation ratio adjustment total value and the first number of battery clusters, and the current allocation target ratio is set for the battery cluster whose second current allocation ratio to be adjusted is within the allocation ratio constraint interval according to the current remaining capacity of the battery cluster.

[0047] In an optional embodiment of the present application, determining the current distribution target ratio according to the magnitude relationship between the total distribution ratio adjustment value and the preset distribution ratio adjustment threshold value further includes:

[0048] If it is detected that the current distribution target ratio set for the battery cluster whose second current distribution ratio is not within the distribution ratio constraint interval is not within the distribution ratio constraint interval, recalculating the total distribution ratio adjustment value corresponding to all battery clusters whose current distribution target ratio is not within the distribution ratio constraint interval;

[0049] Detect the magnitude relationship between the recalculated total value of the allocation ratio adjustment and the preset allocation ratio adjustment threshold, and repeat the following process until a new current allocation target ratio is set for each battery cluster whose current allocation target ratio is not within the allocation ratio constraint interval and is within the allocation ratio constraint interval:

[0050] If the recalculated total value of the allocation ratio adjustment is greater than a preset allocation ratio adjustment threshold, a new current allocation target ratio is set for the battery cluster whose current allocation target ratio is not within the allocation ratio constraint interval according to the allocation ratio constraint lower limit, the recalculated total value of the allocation ratio adjustment and the second number of battery clusters;

[0051] If the recalculated total allocation ratio adjustment value is less than or equal to a preset allocation ratio adjustment threshold, a new current distribution target ratio is set for the battery cluster whose current distribution target ratio is not within the allocation ratio constraint interval based on the allocation ratio constraint upper limit, the recalculated total allocation ratio adjustment value and the first number of battery clusters.

[0052] In a second aspect, an embodiment of the present application further provides an analog circuit for applying the current distribution method as described above, the analog circuit comprising: a main relay, a first relay, a second relay, a third relay, a controlled current source and a controlled voltage source;

[0053] The controlled current source is connected in series with the first relay to form a first controlled branch, the controlled voltage source is connected in series with the second relay to form a second controlled branch, the first controlled branch is connected in parallel with the second controlled branch and then connected in series with the main relay, and the third relay is connected in parallel with the controlled current source.

[0054] The current distribution method and simulation circuit provided in the embodiments of the present application first determine the distribution ratio constraint interval set for each battery cluster according to the total number of battery clusters of multiple battery clusters connected in parallel in the battery energy storage system, and then determine the current distribution target ratio set for each battery cluster according to the battery cluster parameters, wherein the current distribution target ratio is within the distribution ratio constraint interval, and the battery cluster parameters include at least one of the following items: the current remaining capacity of the battery cluster, the capacity setting critical value and the distribution ratio constraint interval; finally, current is distributed to each battery cluster according to the current distribution target ratio.

[0055] Compared with the current control algorithm in the prior art which only considers the difference in state of charge or only considers the difference in battery capacity to calculate the current distribution ratio set for each battery cluster, the embodiment of the present application first defines the distribution ratio constraint interval set for each battery cluster, so that regardless of whether the difference in the initial state of charge of each battery cluster is too large, the current distribution target ratio set for each battery cluster can be controlled within the distribution ratio constraint interval, thereby avoiding excessive difference in the current distribution target ratio of each battery cluster when the difference in the initial state of charge is too large. This not only enables the state of charge of each battery cluster to reach a consensus more quickly, but also avoids the problem of overload of the battery energy storage system caused by oscillation caused by the outside of the battery energy storage system when the difference in the current distribution ratio is large. Then, the current distribution target ratio set for each battery cluster is determined according to the battery cluster parameters, and the battery cluster parameters include at least one of the following items: the current remaining capacity of the battery cluster, the capacity setting critical value and the distribution ratio constraint interval. The DC converter in the battery energy storage system can accurately distribute current to each battery cluster according to the current distribution target ratio in the above manner, and the current distribution target ratio can be configured as a limit ratio within the distribution ratio constraint interval, so that the DC converter is charged and discharged with an allowable limit current, thereby ensuring that battery clusters of different capacities can quickly reach equilibrium during operation, thereby increasing the stability and reliability of the battery energy storage system.

[0056] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0058] Figure 1 A flow chart of a current distribution method provided in an embodiment of the present application;

[0059] Figure 2 A flow chart of another current distribution method provided in an embodiment of the present application;

[0060] Figure 3 A schematic diagram of a first state of an analog circuit provided in an embodiment of the present application;

[0061] Figure 4 A schematic diagram of a second state of an analog circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0062] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application usually described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, each other embodiment obtained by those skilled in the art without making creative work belongs to the scope of protection of the present application.

[0063] The terms "a", "an", "the" and "said" are used in this specification to indicate the presence of one or more elements / components / etc.; the terms "including" and "having" are used to express an open-ended inclusion and mean that additional elements / components / etc. may exist in addition to the listed elements / components / etc.; the terms "first" and "second" etc. are used only as labels and are not intended to limit the quantity of their objects.

[0064] It should be understood that in the embodiments of the present application, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" is merely a way to describe the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the previous and subsequent associated objects are in an "or" relationship. "Including A, B and / or C" means including any one, any two, or any three of A, B, and C.

[0065] It should be understood that in the embodiments of the present application, "B corresponding to A", "B corresponding to A", "A corresponds to B", or "B corresponds to A" means that B is associated with A, and B can be determined according to A. Determining B according to A does not mean determining B only according to A, and B can also be determined according to A and / or other information.

[0066] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0067] First, the battery energy storage system consists of multiple battery clusters connected in parallel. During the overcharging or overdischarging of the battery cluster, irreversible capacity decay will occur, and overcharging will also bring safety hazards such as combustion or even explosion. In order to avoid overcharging or overdischarging of the battery cluster, the DC converter in the battery energy storage system is often used to achieve precise control of the charging and discharging current of the battery cluster.

[0068] However, in the current current control algorithm, only the difference in charge state or only the difference in battery capacity is considered to calculate the current distribution ratio set for each battery cluster. In this way, at least one charging condition, one discharging condition, one cycling condition, or multiple cycling conditions are required to achieve a balanced state. It is difficult for the battery energy storage system to quickly reach a balanced state during the charging and discharging process.

[0069] Moreover, when the initial state of charge differs too much, such as when there is a partial overload or partial static state, the current difference is too large, and the temperature difference caused by the large current difference is also large, which amplifies the inconsistency of the battery cluster under long-term operation, causing a great impact on the overall life, aging attenuation, availability, and depth of discharge of the battery energy storage system.

[0070] Furthermore, in order to make the charge states of each battery cluster consistent, the current control algorithm may result in current distribution ratios with large differences. When the current distribution ratios vary greatly, the oscillation caused by the outside of the battery energy storage system can easily cause the battery energy storage system to overload.

[0071] Based on this, an embodiment of the present application provides a current distribution method, which can ensure that battery clusters with different capacities quickly reach balance during operation, thereby increasing the stability and reliability of the battery energy storage system.

[0072] See also Figure 1 , Figure 1 This is a flow chart of a current distribution method provided in an embodiment of the present application. Figure 1 As shown in , the current distribution method provided by the embodiment of the present application includes:

[0073] S101, determining an allocation ratio constraint interval set for each battery cluster according to the total number of battery clusters connected in parallel in a battery energy storage system;

[0074] S102, determining a current distribution target ratio set for each battery cluster according to battery cluster parameters; wherein the current distribution target ratio is within a distribution ratio constraint interval, and the battery cluster parameters include at least one of the following items: a current remaining capacity of the battery cluster, a capacity setting critical value, and a distribution ratio constraint interval;

[0075] S103 , allocating current to each battery cluster according to the current allocation target ratio.

[0076] In step S101, the battery energy storage system includes a plurality of battery clusters connected in parallel and a DC converter. The battery cluster includes a plurality of single cells connected in series or in parallel. Even after strict capacity matching, there will still be certain initial capacity differences between the single cells. In addition, during use, due to differences in the temperature and manufacturing process of the single cells, the capacity attenuation of the single cells in the battery cluster may be inconsistent. The DC converter can convert a direct current (DC) power supply into a DC (or approximate DC) power supply of different voltages. It contains a large number of high-speed switching diodes. The high-speed switching diodes have a fast switching speed and can complete the switching operation in a very short time, thereby improving the response speed of the circuit. Among them, it can be operated in the DC converter. Figure 1 The current distribution method shown can achieve accurate control of the charging and discharging current of the battery cluster through the DC converter to avoid overcharging or overdischarging of the battery cluster.

[0077] The total number of battery clusters refers to the total number of all battery clusters included in the battery energy storage system. According to the total number of battery clusters, not only the current sharing ratio set for each battery cluster can be determined, but also the distribution ratio constraint interval set for each battery cluster can be determined.

[0078] Specifically, step S101 includes:

[0079] Step S1011, obtaining the total number of battery clusters of a plurality of battery clusters connected in parallel in the battery energy storage system and an overload constraint ratio of the battery energy storage system, where the overload constraint ratio represents a preset ratio of the current of the battery cluster exceeding the rated current range during charging or discharging.

[0080] Here, overload means that the battery energy storage system can still operate beyond the rated current range under certain abnormal conditions. Among them, the abnormal state refers to the state in which the battery energy storage system operates without a cluster but maintains a constant power / current output. The overload constraint ratio represents the preset proportion of the current of the battery cluster during charging or discharging that exceeds the rated current range, that is, the overload constraint ratio represents the preset proportion of the current of the battery cluster during charging that is allowed to exceed the first current specified value or the preset proportion of the current of the battery cluster during discharging that is allowed to be lower than the second current specified value, wherein the second current specified value is less than the first current specified value, and the range between the first current specified value and the second current specified value constitutes the rated current range.

[0081] Exemplarily, the range of the overload constraint ratio is between 0 and 1. Specifically, the overload constraint ratio may be 0.1.

[0082] Step S1012: Determine an upper limit and a lower limit of an allocation ratio constraint of the battery energy storage system according to the overload constraint ratio, so as to determine an allocation ratio constraint interval set for each battery cluster.

[0083] Specifically, the allocation ratio constraint upper limit and the allocation ratio constraint lower limit are determined as two endpoint values ​​of the allocation ratio constraint interval.

[0084] Exemplarily, step S1012 specifically includes:

[0085] Step S1012a: Determine the total value of the upper limit and the total value of the lower limit of the allocation ratio constraint of the battery energy storage system according to the overload constraint ratio.

[0086] Here, since the overload constraint ratio is between 0 and 1, the total value of the upper limit of the allocation ratio constraint is the sum of 1 and the overload constraint ratio, and the total value of the lower limit of the allocation ratio constraint is the difference between 1 and the overload constraint ratio.

[0087] Step S1012b: Determine the upper and lower limits of the allocation ratio constraints set for each battery cluster by using the ratios of the total values ​​of the upper and lower limits of the allocation ratio constraints to the total number of battery clusters.

[0088] Here, the allocation ratio constraint interval of each battery cluster is the same.

[0089] For example, the total number of battery clusters is defined as n, the overload constraint ratio is defined as limit, and I pct_max represents the upper limit of the allocation ratio constraint, I pct_min represents the lower limit of the allocation ratio constraint; the upper limit of the allocation ratio constraint I pct_max and the lower limit of the allocation ratio constraint I pct_min The calculation formula is as follows:

[0090]

[0091]

[0092] For example, according to the actual configuration parameters of the battery cluster, the limit can be set to 0.1.

[0093]

[0094]

[0095] The embodiment of the present application can adjust the overload constraint ratio in real time according to the actual operation of the battery cluster, and then can flexibly set the upper limit and the lower limit of the allocation ratio constraint. Within the allocation ratio constraint range, the current can be allocated according to the current allocation target ratio set for each battery cluster. Since the range of the current allocation target ratio is locked, the stability and reliability of the battery energy storage system can be further increased.

[0096] In step S102, the battery cluster parameter refers to a parameter associated with the current distribution of the battery cluster, which may be an attribute characteristic of the battery cluster, such as the current remaining capacity of the battery cluster; the parameter may be a numerical value pre-set according to the attribute characteristics of the battery cluster, wherein the preset numerical value may be adjusted in real time and the numerical value is applicable to each battery cluster, such as each battery cluster corresponds to the same capacity setting critical value; the parameter may also be a numerical value calculated according to the attribute characteristics of the battery cluster, such as an allocation ratio constraint interval calculated according to the total number of battery clusters and the overload constraint ratio.

[0097] Here, the current distribution target ratio set for each battery cluster is determined according to the battery cluster parameters, and the current distribution target ratio is within the distribution ratio constraint interval. That is, the current distribution target ratio set for each battery cluster can be accurately determined according to the battery cluster parameters, so that the current is distributed to each battery cluster according to the current distribution target ratio, so that battery clusters with different capacities can reach balance as soon as possible during operation.

[0098] Furthermore, when the charge states of the battery clusters differ greatly, the current distribution target ratios of the battery clusters differ, but the differences in the current distribution target ratios are guaranteed to be within the distribution ratio constraint range, so that the charge states of the battery clusters can be made consistent at a faster speed while avoiding the problem of overload of the battery energy storage system due to external oscillations to the greatest extent, thereby achieving balanced management and safe use, and further extending the service life of the battery clusters in the battery energy storage system.

[0099] In a preferred embodiment, the battery cluster parameters include the current remaining capacity of the battery cluster and a capacity setting critical value; here, the current remaining capacity refers to the maximum chargeable or dischargeable capacity of the battery cluster under the current working state, and the capacity setting critical value represents the fastest convergence of each battery cluster in the battery energy storage system to a consistent state of charge. Exemplarily, the capacity setting critical value can be the minimum value among the current remaining capacities of multiple battery clusters.

[0100] Here, a capacity adjustment limit range is pre-set for the capacity setting critical value, and when adjusting the capacity setting critical value, the capacity adjustment limit range cannot be exceeded. Specifically, when multiple battery clusters in the battery energy storage system are in a discharging condition or a charging condition, the capacity adjustment limit range corresponds to a range between 0 and the capacity setting critical value.

[0101] Wherein, step S102 specifically includes:

[0102] Step 1021 : Determine a first current distribution ratio to be adjusted for each battery cluster according to the current remaining capacity and the capacity setting critical value of each battery cluster.

[0103] Specifically, the capacity difference between the current remaining capacity of each battery cluster and the capacity setting critical value is calculated, the sum of the capacity differences corresponding to all battery clusters is calculated, and for each battery cluster, the ratio between the capacity difference corresponding to the battery cluster and the sum of the capacity differences is calculated, and the ratio is determined as the first current distribution ratio to be adjusted.

[0104] Exemplarily, the first current distribution ratio to be adjusted of the i-th battery cluster is defined as I 1i,pct , the capacity setting threshold is min_cap, and the current remaining capacity is cap i , the total number of battery clusters is n; furthermore, the first current distribution ratio to be adjusted for the i-th battery cluster is I 1i,pct The calculation formula is as follows:

[0105]

[0106] By using the above formula, the first current distribution ratio to be adjusted corresponding to each battery cluster can be calculated, and the purpose of quickly distributing current to the battery cluster can be achieved according to the first current distribution ratio to be adjusted.

[0107] Step 1022: Determine a current distribution target ratio according to whether the first current distribution ratio to be adjusted is within the distribution ratio constraint interval.

[0108] Wherein, step 1022 specifically includes:

[0109] Step 1022a: if it is detected that the first current allocation ratio to be adjusted set for each battery cluster is within the allocation ratio constraint interval, determine the first current allocation ratio to be adjusted for each battery cluster within the allocation ratio constraint interval as the corresponding current allocation target ratio for each battery cluster.

[0110] Here, if the first current distribution ratio to be adjusted corresponding to each battery cluster is within the distribution ratio constraint interval, the currently calculated first current distribution ratio to be adjusted can be determined as the current distribution target ratio to distribute current to the battery cluster according to the first current distribution ratio to be adjusted.

[0111] Step 1022b: If it is detected that the first current distribution ratio to be adjusted set for the battery cluster is not within the distribution ratio constraint interval, the capacity setting critical value is adjusted, and the first current distribution ratio to be adjusted set for each battery cluster is re-determined based on the current remaining capacity of each battery cluster and the adjusted capacity setting critical value, until the first current distribution ratio to be adjusted set for each battery cluster is within the distribution ratio constraint interval, and the first current distribution ratio to be adjusted for each battery cluster within the distribution ratio constraint interval is determined to be the corresponding current distribution target ratio for each battery cluster.

[0112] That is, when it is detected that the first current allocation ratio to be adjusted corresponding to the battery cluster is not within the allocation ratio constraint interval, the capacity setting critical value can be adjusted. For example, the capacity setting critical value can be reduced, and then the first current allocation ratio to be adjusted set for each battery cluster is recalculated according to the calculation formula of the first current allocation ratio to be adjusted in step 1021, until the capacity setting critical value is adjusted to the minimum value of the capacity adjustment limit range, such as the minimum value of the capacity adjustment limit range is 0. If it is detected that the first current allocation ratio to be adjusted corresponding to each battery cluster is within the allocation ratio constraint interval under the condition that the capacity setting critical value is within the capacity adjustment limit range, then the currently determined first current allocation ratio to be adjusted can be determined as the current allocation target ratio.

[0113] Step 1023: if it is detected that the adjusted capacity setting critical value is not within the capacity adjustment limit range, and there is a first current allocation ratio to be adjusted that is re-set for the battery cluster and is not within the allocation ratio constraint interval, then determine a second current allocation ratio to be adjusted that is set for each battery cluster according to the current remaining capacity of each battery cluster;

[0114] Here, the current remaining capacities of all battery clusters are summed to obtain the current remaining capacity sum value, and for each battery cluster, the ratio between the current remaining capacity corresponding to the battery cluster and the current remaining capacity sum value is calculated, and the ratio is determined as the second current distribution ratio to be adjusted.

[0115] Exemplarily, the second current distribution ratio to be adjusted of the i-th battery cluster is defined as I 2i,pct , and then, the second current distribution ratio to be adjusted for the i-th battery cluster is I 2i,pct The calculation formula is as follows:

[0116]

[0117] The second current distribution ratio to be adjusted corresponding to each battery cluster can be calculated by the above formula, and the purpose of quickly distributing current to the battery cluster can be achieved according to the second current distribution ratio to be adjusted.

[0118] Step 1024: Determine the current distribution target ratio according to whether the second current distribution ratio to be adjusted is within the distribution ratio constraint interval.

[0119] Wherein, step 1024 specifically includes:

[0120] Step 1024a: if it is detected that the second current allocation ratio to be adjusted set for each battery cluster is within the allocation ratio constraint interval, determine the second current allocation ratio to be adjusted for each battery cluster within the allocation ratio constraint interval as the corresponding current allocation target ratio for each battery cluster.

[0121] Here, if the second current distribution ratio to be adjusted corresponding to each battery cluster is within the distribution ratio constraint interval, the currently calculated second current distribution ratio to be adjusted can be determined as the current distribution target ratio to distribute current to the battery cluster according to the second current distribution ratio to be adjusted.

[0122] Step 1024b: If it is detected that the second current distribution ratio to be adjusted set for the battery cluster is not within the distribution ratio constraint interval, determine the number of first battery clusters corresponding to the battery clusters whose second current distribution ratio to be adjusted is greater than the upper limit of the distribution ratio constraint and the number of second battery clusters corresponding to the battery clusters whose second current distribution ratio to be adjusted is less than the lower limit of the distribution ratio constraint.

[0123] The battery cluster parameter includes an allocation ratio constraint interval, and the allocation ratio constraint interval includes an allocation ratio constraint upper limit and an allocation ratio constraint lower limit. The first battery cluster quantity can be determined according to the allocation ratio constraint upper limit, and the second battery cluster quantity can be determined according to the allocation ratio constraint lower limit.

[0124] Step 1024c, determine the allocation ratio adjustment value of the second current allocation ratio to be adjusted that is not within the allocation ratio constraint interval to the closest allocation ratio constraint upper limit or allocation ratio constraint lower limit, so as to obtain the total allocation ratio adjustment value corresponding to all battery clusters whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval.

[0125] Among them, the allocation ratio adjustment value adjusted from the second current allocation ratio to be adjusted which is less than the allocation ratio constraint lower limit to the allocation ratio constraint lower limit is a negative value, and the allocation ratio adjustment value adjusted from the second current allocation ratio to be adjusted which is greater than the allocation ratio constraint upper limit to the allocation ratio constraint upper limit is a positive value.

[0126] Here, the difference between the second current distribution ratio to be adjusted and the closest upper or lower limit of the distribution ratio constraint is calculated, and the difference is the distribution ratio adjustment value. Specifically, the difference can be positive or negative. The distribution ratio adjustment value obtained by subtracting the second current distribution ratio to be adjusted that is less than the lower limit of the distribution ratio constraint from the lower limit of the distribution ratio constraint is a negative value; the distribution ratio adjustment value obtained by subtracting the second current distribution ratio to be adjusted that is greater than the upper limit of the distribution ratio constraint from the upper limit of the distribution ratio constraint is a positive value. The distribution ratio adjustment values ​​corresponding to all battery clusters whose second current distribution ratio to be adjusted is not within the distribution ratio constraint interval are summed to obtain the total distribution ratio adjustment value. Here, since the distribution ratio adjustment value can be positive or negative, the calculated total distribution ratio adjustment value can be either positive or negative.

[0127] Step 1025 : Determine the current distribution target ratio according to the magnitude relationship between the total distribution ratio adjustment value and the preset distribution ratio adjustment threshold.

[0128] Wherein, step 1025 specifically includes:

[0129] Step 1025a, if the total value of the allocation ratio adjustment is less than or equal to the preset allocation ratio adjustment threshold, then determine the current allocation target ratio for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval according to the allocation ratio constraint lower limit, the allocation ratio adjustment total value and the number of second battery clusters, and determine the current allocation target ratio for the battery cluster whose second current allocation ratio to be adjusted is within the allocation ratio constraint interval according to the current remaining capacity of the battery cluster.

[0130] Exemplarily, the preset allocation ratio adjustment threshold value may be 0. Among them, for the second current allocation ratios to be adjusted corresponding to the battery clusters calculated in step 1023, if the second current allocation ratios to be adjusted corresponding to some or all of the battery clusters are not within the allocation ratio constraint interval, then for the battery clusters whose second current allocation ratios to be adjusted are not within the allocation ratio constraint interval, the new calculation method involved in step 1025 is used to calculate the current allocation target ratio, and for the battery clusters whose second current allocation ratios to be adjusted are within the allocation ratio constraint interval, the calculation method involved in step 1023 is continued to be used to calculate the current allocation target ratio.

[0131] Here, if the total value of the allocation ratio adjustment is less than or equal to the preset allocation ratio adjustment threshold, for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval, the current allocation target ratio is determined by the following calculation method:

[0132] The allocation ratio adjustment mean is determined by using the ratio between the total allocation ratio adjustment value and the number of the second battery clusters; and the current allocation target ratio is determined to be set for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval by using the sum of the allocation ratio constraint lower limit and the allocation ratio adjustment mean.

[0133] For example, the current distribution target ratio of the i-th battery cluster is defined as I 32i,pct , the number of the second battery cluster is n2, the total value of the allocation ratio adjustment is Vol, and then, the current allocation target ratio of the i-th battery cluster is I 32i,pct The calculation formula is as follows:

[0134]

[0135] Step 1025b, if the total value of the allocation ratio adjustment is less than or equal to the preset allocation ratio adjustment threshold, then determine the current allocation target ratio for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval according to the allocation ratio constraint upper limit, the allocation ratio adjustment total value and the number of the first battery clusters, and determine the current allocation target ratio for the battery cluster whose second current allocation ratio to be adjusted is within the allocation ratio constraint interval according to the current remaining capacity of the battery cluster.

[0136] Here, if the total value of the allocation ratio adjustment is less than or equal to the preset allocation ratio adjustment threshold, for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval, the current allocation target ratio is determined by the following calculation method:

[0137] The allocation ratio adjustment mean is determined by using the ratio between the total allocation ratio adjustment value and the number of the first battery clusters; and the current allocation target ratio is determined to be set for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval by using the sum of the allocation ratio constraint upper limit and the allocation ratio adjustment mean.

[0138] For example, the current distribution target ratio of the i-th battery cluster is defined as I 31i,pct , the number of the first battery cluster is n1, the total value of the allocation ratio adjustment is Vol, and then, the current allocation target ratio of the i-th battery cluster is I 31i,pct The calculation formula is as follows:

[0139]

[0140] It should be noted that when the second current allocation ratio to be adjusted is not within the allocation ratio constraint interval, the current allocation target ratio is directly calculated through step 1025a or step 1025b according to the size relationship between the allocation ratio adjustment total value and the preset allocation ratio adjustment threshold.

[0141] Step 1025c: if it is detected that the current distribution target ratio set for the battery cluster whose second current distribution ratio to be adjusted is not within the distribution ratio constraint interval is not within the distribution ratio constraint interval, recalculate the total distribution ratio adjustment value corresponding to all battery clusters whose current distribution target ratio is not within the distribution ratio constraint interval;

[0142] Detect the relationship between the recalculated total allocation ratio adjustment value and the preset allocation ratio adjustment threshold, and loop through step 1025a and / or step 1025b until a new current allocation target ratio is set for each battery cluster whose current allocation target ratio is not within the allocation ratio constraint interval and is within the allocation ratio constraint interval.

[0143] The current distribution target ratio finally obtained in step 1025c can be guaranteed to be within the distribution ratio constraint interval, and no further calculation is required in other ways.

[0144] Through the above method, different calculation methods can be used to determine the current distribution target ratio under different parameter conditions, so that the current can be accurately distributed to each battery cluster according to the current distribution target ratio, so that battery clusters with different capacities can reach balance as quickly as possible during operation.

[0145] In step S103, current is allocated to each battery cluster according to the current allocation target ratio determined in step S102. In this way, regardless of whether the difference in the initial state of charge of each battery cluster is too large, it can be controlled within the constraint range corresponding to the allocation ratio constraint interval, and can be quickly allocated according to the maximum current output capacity of the allocation ratio constraint interval, so that each battery cluster of the battery energy storage system can reach equilibrium at the fastest speed within the current allowable range.

[0146] See also Figure 2 , Figure 2 This is a flow chart of another current distribution method provided by an embodiment of the present application. Figure 2 As shown in , the current distribution method provided by the embodiment of the present application includes:

[0147] S201, when the system parameters of the battery energy storage system do not satisfy the current balancing condition, determining an allocation ratio constraint interval set for each battery cluster according to the total number of battery clusters in the battery energy storage system that are connected in parallel;

[0148] S202, determining a current distribution target ratio set for each battery cluster according to battery cluster parameters; wherein the current distribution target ratio is within a distribution ratio constraint interval, and the battery cluster parameters include at least one of the following items: a current remaining capacity of the battery cluster, a capacity setting critical value, and a distribution ratio constraint interval; and distributing current to each battery cluster according to the current distribution target ratio;

[0149] S203: When the system parameters of the battery energy storage system meet the current sharing condition, determine the current sharing ratio set for each battery cluster according to the total number of battery clusters; and distribute current to each battery cluster according to the current sharing ratio.

[0150] The description of step S202 may refer to step S102 and will not be repeated here.

[0151] In step S201, the current sharing condition includes one of the following items: the battery energy storage system is in a static working condition, the 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 discharge is not greater than a first preset ratio, the maximum state of charge of the battery energy storage system during charging is not less than a second preset ratio, the first preset ratio is less than the second preset ratio, and the state of charge difference is less than a preset difference threshold, and the state of charge difference 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.

[0152] The total number of battery clusters connected in parallel, the initial state of charge of each battery cluster, the current remaining capacity of each battery cluster, and the system operating conditions are counted by the battery management system (BMS). The system operating conditions include static conditions, charging conditions, or discharging conditions. The system parameters of the battery energy storage system are judged based on the above data collected by the BMS to determine whether they meet the current balancing conditions.

[0153] Exemplarily, in order to prevent the capacity difference between the current remaining capacities of the battery clusters in the battery energy storage system from being too large, the preset difference threshold is selected to be a smaller value, such as 1%.

[0154] Here, when the system parameters of the battery energy storage system do not meet the above current sharing conditions, the allocation ratio constraint interval set for each battery cluster is determined according to the total number of battery clusters in the battery energy storage system that are connected in parallel. The specific implementation method can refer to step S101 and will not be repeated here.

[0155] Furthermore, in step S203, when the system parameters of the battery energy storage system meet the current sharing condition, the current sharing ratio set for each battery cluster is determined according to the total number of battery clusters; and current is distributed to each battery cluster according to the current sharing ratio.

[0156] That is to say, when the battery energy storage system is in a static condition, the DC converter in the battery energy storage system is in a faulty state, the minimum state of charge of the battery energy storage system during discharge is not greater than a first preset ratio, and the maximum state of charge of the battery energy storage system during charging is not less than a second preset ratio, the first preset ratio is less than the second preset ratio. Exemplarily, the first preset ratio is 10%, the second preset ratio is 90%, the state of charge difference is less than a preset difference threshold, the state of charge difference 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, and the current sharing ratio set for each battery cluster is directly determined according to the total number of battery clusters.

[0157] Exemplarily, the current sharing ratio is determined by the following formula:

[0158]

[0159] Where n represents the total number of battery clusters.

[0160] By determining the current sharing ratio set for each battery cluster in the above manner, it is possible to quickly distribute current to each battery cluster, which is relatively simple and convenient.

[0161] The embodiment of the present application first defines the allocation ratio constraint interval set for each battery cluster, so that regardless of whether the difference in the initial state of charge of each battery cluster is too large, the current allocation target ratio set for each battery cluster can be controlled within the allocation ratio constraint interval, avoiding the current allocation target ratio difference of each battery cluster being too large when the initial state of charge difference is too large, which can not only make the state of charge of each battery cluster reach a consensus quickly, but also avoid the problem that the oscillation caused by the outside of the battery energy storage system is easy to cause the battery energy storage system to overload when the current allocation ratio difference is large. Then, the current allocation target ratio set for each battery cluster is determined according to the battery cluster parameters, and the battery cluster parameters include at least one of the following items: the current remaining capacity of the battery cluster, the capacity setting critical value and the allocation ratio constraint interval. The DC converter in the battery energy storage system can accurately allocate current to each battery cluster according to the current allocation target ratio in the above manner, and the current allocation target ratio can be configured as the limit ratio within the allocation ratio constraint interval, so that the DC converter is charged and discharged with an allowable limit current, thereby ensuring that battery clusters of different capacities quickly reach equilibrium during operation, thereby increasing the stability and reliability of the battery energy storage system.

[0162] In the relevant scheme, the actual DC / DC contains many high-speed switching tubes, and it is difficult to obtain ideal results in a short time through simulation, resulting in a slow simulation speed. Especially for the series DC / DC in the battery energy storage system, due to the complex circuit structure of the series DC / DC, directly verifying the operation of the current distribution method will result in a low verification rate, and it is difficult to obtain the final verification result in a short time. In addition, since the internal resistance of the ideal current source is infinite and the internal resistance of the ideal voltage source is infinitesimal, the ideal current source cannot be open-circuited and the ideal voltage source cannot be short-circuited, resulting in circuit modeling errors and inability to calculate.

[0163] Based on this, the embodiment of the present application provides an analog circuit for application such as Figure 1 or Figure 2 The current distribution method shown is as follows: Figure 3 or Figure 4 As shown, 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; the controlled current source 405 is connected in series with the first relay 402 to form a first controlled branch, the controlled voltage source 406 is connected in series with the second relay 403 to form a second controlled branch, the first controlled branch is connected in parallel with the second controlled branch and then connected in series with the main relay 401, and the third relay 404 is connected in parallel with the controlled current source 405.

[0164] Here, the above analog circuit is used for the battery cluster series DC / DC in the equivalent battery energy storage system.

[0165] The embodiment of the present application realizes the decoupling control of voltage and current through an ideal current source, an ideal voltage source and a relay, and avoids the simulation calculation problem caused by the infinite / infinitely small internal resistance of the ideal power supply. Figure 1 or Figure 2 The current distribution algorithm shown can realize the charging and discharging of the series DC / DC at the allowable limit current, and the current distribution target ratio of each battery cluster will not be too different when the state of charge difference is too large, so that the state of charge of each battery cluster reaches consistency at the fastest speed, and the problem of overload of the battery energy storage system due to external oscillation can be avoided to the greatest extent. At the same time, it can also avoid the problem of using the series DC / DC with a relatively complex circuit structure in the prior art to verify the operation of the current distribution method in the embodiment of the present application, which makes it difficult to obtain the final verification result in a short time.

[0166] like Figure 3 As shown, the analog circuit is in the first state, and no-load voltage regulation can be performed at this time:

[0167] The DC / DC has a voltage regulation capability of 10V to 20V. When the main relay Ks is disconnected, the series DC / DC equivalent to the analog circuit is a series controlled voltage source, whose value defaults to 10V. The relay Ks1 connected in series with the controlled current source 405 is in the same state as the main relay Ks (disconnected), and the controlled voltage source 406 connected in series with the relay Ks2 is in the opposite state to the main relay Ks (closed). Therefore, the series DC / DC equivalent to the analog circuit is expressed as the controlled voltage source 406 connected in series between the main relay Ks and the positive electrode of the battery, and the voltage inside the main relay Ks is the battery voltage plus the voltage of the controlled voltage source 406; because the ideal current source has infinite internal resistance and is not allowed to be open-circuited, it is short-circuited through the relay Ks3, and the state of the relay Ks3 is opposite to that of the main relay Ks.

[0168] like Figure 4 As shown, the analog circuit is in the second state, and current regulation can be performed at this time:

[0169] When the voltage meets the closing condition and the main relay Ks is closed, relay Ks1 is consistent with the main relay Ks (closed), and relay Ks2 and relay Ks3 are disconnected. At this time, the equivalent series DC / DC of the analog circuit is reflected as a series controlled current source 405. The current distribution algorithm can be used to accurately control the current of each battery cluster to achieve the balance requirement between clusters. At the same time, a positive and negative parallel controlled voltage source 406 is required on the DC bus, and its value is the minimum value of the current terminal voltage of all cabinets plus 20V. Since the terminal voltage difference between clusters does not exceed 10V when Δsoc<10%, when the bus voltage is the minimum cluster terminal voltage plus 20V, the voltage regulation capability of the series DC / DC within 20V can fully cover the voltage regulation requirements of all cabinet clusters that have been connected. The series DC / DC voltage after the analog circuit is connected is the voltage difference between the bus voltage and the terminal voltage, and is automatically adjusted by the ideal current source.

[0170] The embodiment of the present application solves the high-speed operation requirements of the switching diode of the real series DC / DC by constructing an analog circuit, and can reflect the external characteristics of the real series DC / DC on the analog circuit by constructing an ideal power supply. The ideal power supply and the relay are connected in series and parallel to solve the characteristics that the ideal current source cannot be open-circuited and the ideal voltage source cannot be short-circuited. Furthermore, the analog circuit can speed up the simulation speed, and thus quickly verify 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 it is actually applied.

[0171] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present application, which are used to illustrate the technical solutions of the present application, rather than to limit them. The protection scope of the present application is not limited thereto. Although the present application is described in detail with reference to the above-mentioned embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-mentioned embodiments within the technical scope disclosed in the present application, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A current distribution method, characterized in that: The method comprises: Determine an allocation ratio constraint interval set for each battery cluster according to the total number of battery clusters connected in parallel in the battery energy storage system; Determine a current distribution target ratio set for each battery cluster according to a battery cluster parameter; wherein the current distribution target ratio is within the distribution ratio constraint interval, and the battery cluster parameter includes at least one of the following items: a current remaining capacity of the battery cluster, a capacity setting critical value, and the distribution ratio constraint interval; Current is distributed to each battery cluster according to the current distribution target ratio.

2. The method according to claim 1, characterized in that The allocation ratio constraint interval set for each battery cluster is determined according to the total number of battery clusters in the battery energy storage system and connected in parallel, including: When the system parameters of the battery energy storage system do not satisfy the current balancing condition, an allocation ratio constraint interval set for each battery cluster is determined according to the total number of battery clusters in the battery energy storage system that are connected in parallel.

3. The method according to claim 2, characterized in that The method further comprises: When the system parameters of the battery energy storage system meet the current sharing condition, determine the current sharing ratio set for each battery cluster according to the total number of battery clusters; The current is distributed to each battery cluster according to the current sharing ratio.

4. The method according to claim 2 or 3, characterized in that: The current sharing condition includes one of the following items: the battery energy storage system is in a static working condition, the 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 discharge is not greater than a first preset ratio, the maximum state of charge of the battery energy storage system during charging is not less than a second preset ratio, the first preset ratio is less than the second preset ratio, and the state of charge difference is less than a preset difference threshold, and the state of charge difference 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.

5. The method according to claim 1, characterized in that The allocation ratio constraint interval set for each battery cluster is determined according to the total number of battery clusters in the battery energy storage system and connected in parallel, including: Obtaining a total number of battery clusters of a plurality of battery clusters connected in parallel in a battery energy storage system and an overload constraint ratio of the battery energy storage system, wherein the overload constraint ratio represents a preset ratio of a current of the battery cluster exceeding a rated current range during charging or discharging; According to the overload constraint ratio, an upper limit and a lower limit of an allocation ratio constraint of the battery energy storage system are determined to determine an allocation ratio constraint interval set for each battery cluster.

6. The method according to claim 5, characterized in that The step of determining the upper limit and the lower limit of the allocation ratio constraint of the battery energy storage system according to the overload constraint ratio includes: Determine, according to the overload constraint ratio, a total value of an upper limit constraint of an allocation ratio and a total value of a lower limit constraint of an allocation ratio of the battery energy storage system; The upper and lower limits of the allocation ratio constraints set for each battery cluster are determined by using the ratios of the total value of the allocation ratio constraint upper limits and the total value of the allocation ratio constraint lower limits to the total number of battery clusters.

7. The method according to claim 1, characterized in that The battery cluster parameters include the current remaining capacity of the battery cluster and the capacity setting critical value; wherein the capacity setting critical value represents the fastest convergence of each battery cluster in the battery energy storage system to a consistent state of charge; The step of determining the current distribution target ratio set for each battery cluster according to the battery cluster parameters includes: Determining a first current distribution ratio to be adjusted for each battery cluster according to the current remaining capacity of each battery cluster and the capacity setting critical value; The current distribution target ratio is determined according to whether the first current distribution ratio to be adjusted is within the distribution ratio constraint interval.

8. The method according to claim 7, characterized in that The step of determining the current distribution target ratio according to whether the first current distribution ratio to be adjusted is within the distribution ratio constraint interval includes: If it is detected that the first current distribution ratio to be adjusted set for each battery cluster is within the distribution ratio constraint interval, the first current distribution ratio to be adjusted for each battery cluster within the distribution ratio constraint interval is determined as the current distribution target ratio of each corresponding battery cluster.

9. The method according to claim 7, characterized in that: The determining the current distribution target ratio according to whether the first current distribution ratio to be adjusted is within the distribution ratio constraint interval also includes: If it is detected that the first current distribution ratio to be adjusted set for the battery cluster is not within the distribution ratio constraint interval, the capacity setting critical value is adjusted, and the first current distribution ratio to be adjusted set for each battery cluster is re-determined based on the current remaining capacity of each battery cluster and the adjusted capacity setting critical value, until the first current distribution ratio to be adjusted set for each battery cluster is within the distribution ratio constraint interval, and the first current distribution ratio to be adjusted for each battery cluster within the distribution ratio constraint interval is determined to be the corresponding current distribution target ratio for each battery cluster.

10. The method according to claim 7, characterized in that The step of determining the current distribution target ratio set for each battery cluster according to the battery cluster parameters also includes: If it is detected that the adjusted capacity setting critical value is not within the capacity adjustment limit range, and there is a first current allocation ratio to be adjusted that is re-set for the battery cluster that is not within the allocation ratio constraint interval, then determine the second current allocation ratio to be adjusted that is set for each battery cluster according to the current remaining capacity of each battery cluster; The current distribution target ratio is determined according to whether the second current distribution ratio to be adjusted is within the distribution ratio constraint interval.

11. The method according to claim 10, characterized in that The step of determining the current distribution target ratio according to whether the second current distribution ratio to be adjusted is within the distribution ratio constraint interval includes: If it is detected that the second current distribution ratio to be adjusted set for each battery cluster is within the distribution ratio constraint interval, the second current distribution ratio to be adjusted for each battery cluster within the distribution ratio constraint interval is determined as the corresponding current distribution target ratio for each battery cluster.

12. The method according to claim 10, characterized in that The battery cluster parameter includes an allocation ratio constraint interval, and the allocation ratio constraint interval includes an allocation ratio constraint upper limit and an allocation ratio constraint lower limit; The determining of the current distribution target ratio according to whether the second current distribution ratio to be adjusted is within the distribution ratio constraint interval further includes: If it is detected that the second current allocation ratio to be adjusted set for the battery cluster is not within the allocation ratio constraint interval, then respectively determining the number of first battery clusters corresponding to battery clusters whose second current allocation ratio to be adjusted is greater than the upper limit of the allocation ratio constraint and the number of second battery clusters corresponding to battery clusters whose second current allocation ratio to be adjusted is less than the lower limit of the allocation ratio constraint; Determine an allocation ratio adjustment value of adjusting the second current allocation ratio to be adjusted that is not within the allocation ratio constraint interval to the closest allocation ratio constraint upper limit or allocation ratio constraint lower limit, so as to obtain a total allocation ratio adjustment value corresponding to all battery clusters whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval; The current distribution target ratio is determined according to the magnitude relationship between the total distribution ratio adjustment value and the preset distribution ratio adjustment threshold.

13. The method according to claim 12, characterized in that The allocation ratio adjustment value adjusted from the second current allocation ratio to be adjusted which is less than the allocation ratio constraint lower limit to the allocation ratio constraint lower limit is a negative value, and the allocation ratio adjustment value adjusted from the second current allocation ratio to be adjusted which is greater than the allocation ratio constraint upper limit to the allocation ratio constraint upper limit is a positive value.

14. The method according to claim 13, characterized in that The step of determining the current distribution target ratio according to the magnitude relationship between the total distribution ratio adjustment value and a preset distribution ratio adjustment threshold value includes: If the total value of the allocation ratio adjustment is greater than the preset allocation ratio adjustment threshold, the current allocation target ratio is set for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval according to the allocation ratio constraint lower limit, the total value of the allocation ratio adjustment and the second number of battery clusters, and the current allocation target ratio is set for the battery cluster whose second current allocation ratio to be adjusted is within the allocation ratio constraint interval according to the current remaining capacity of the battery cluster.

15. The method according to claim 14, characterized in that Determining, according to the allocation ratio constraint lower limit, the allocation ratio adjustment total value, and the second battery cluster quantity, setting a current allocation target ratio for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval includes: Determine an allocation ratio adjustment mean value by using a ratio between the allocation ratio adjustment total value and the number of the second battery clusters; By using the sum of the allocation ratio constraint lower limit and the allocation ratio adjustment mean value, it is determined to set a current allocation target ratio for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval.

16. The method according to claim 13, characterized in that The step of determining the current distribution target ratio according to the magnitude relationship between the total distribution ratio adjustment value and the preset distribution ratio adjustment threshold value further includes: If the total allocation ratio adjustment value is less than or equal to a preset allocation ratio adjustment threshold, then the current allocation target ratio is set for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval according to the allocation ratio constraint upper limit, the allocation ratio adjustment total value and the first number of battery clusters, and the current allocation target ratio is set for the battery cluster whose second current allocation ratio to be adjusted is within the allocation ratio constraint interval according to the current remaining capacity of the battery cluster.

17. The method according to claim 13, characterized in that The step of determining the current distribution target ratio according to the magnitude relationship between the total distribution ratio adjustment value and the preset distribution ratio adjustment threshold value further includes: If it is detected that the current distribution target ratio set for the battery cluster whose second current distribution ratio is not within the distribution ratio constraint interval is not within the distribution ratio constraint interval, recalculating the total distribution ratio adjustment value corresponding to all battery clusters whose current distribution target ratio is not within the distribution ratio constraint interval; Detect the magnitude relationship between the recalculated total value of the allocation ratio adjustment and the preset allocation ratio adjustment threshold, and repeat the following process until a new current allocation target ratio is set for each battery cluster whose current allocation target ratio is not within the allocation ratio constraint interval and is within the allocation ratio constraint interval: If the recalculated total value of the allocation ratio adjustment is greater than a preset allocation ratio adjustment threshold, a new current allocation target ratio is set for the battery cluster whose current allocation target ratio is not within the allocation ratio constraint interval according to the allocation ratio constraint lower limit, the recalculated total value of the allocation ratio adjustment and the second number of battery clusters; If the recalculated total allocation ratio adjustment value is less than or equal to a preset allocation ratio adjustment threshold, a new current distribution target ratio is set for the battery cluster whose current distribution target ratio is not within the allocation ratio constraint interval based on the allocation ratio constraint upper limit, the recalculated total allocation ratio adjustment value and the first number of battery clusters.

18. An analog circuit, characterized in that: For applying the current distribution method according to any one of claims 1 to 17, the simulation circuit comprises: a main relay, a first relay, a second relay, a third relay, a controlled current source and a controlled voltage source; The controlled current source is connected in series with the first relay to form a first controlled branch, the controlled voltage source is connected in series with the second relay to form a second controlled branch, the first controlled branch is connected in parallel with the second controlled branch and then connected in series with the main relay, and the third relay is connected in parallel with the controlled current source.

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