Current distribution method and analog circuit

Abstract

A current distribution method and an analog circuit, which can ensure that battery clusters with different capacities are quickly balanced during operation, thereby achieving the effect of improving the stability and reliability of a battery energy storage system. The method comprises: on the basis of the total number of battery clusters connected in parallel in a battery energy storage system, determining a distribution proportion constraint interval, which is set for each battery cluster (S101); on the basis of a battery cluster parameter, determining a target current distribution proportion, which is set for each battery cluster, wherein the target current distribution proportion falls within the distribution proportion constraint interval, and the battery cluster parameter comprises at least one of the following: the current remaining capacity of the battery cluster, a set critical capacity value, and the distribution proportion constraint interval (S102); and on the basis of the target current distribution proportions, distributing currents to the respective battery clusters (S103).

Description

A current distribution method and analog circuit

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure claims priority to Chinese patent application number 202311444824.3, filed with the State Intellectual Property Office of China on November 1, 2023, entitled “A Current Distribution Method and Analog Circuit,” the entire contents of which are incorporated by reference into this disclosure. Technical Field

[0003] The present disclosure relates to the field of circuit technology, and in particular to a current distribution method and an analog circuit. Background Art

[0004] Battery energy storage systems consist of multiple battery clusters connected in parallel. Overcharging or overdischarging a battery cluster can cause irreversible capacity degradation, and overcharging can also pose safety risks such as combustion or even explosion. To prevent overcharging or overdischarging, direct current (DC / DC) converters are often used within battery energy storage systems to precisely control the charging and discharging currents of the battery cluster.

[0005] However, current current control algorithms only consider differences in state of charge (SOC) or battery capacity to calculate the current distribution ratio for each battery cluster, making it difficult for the battery energy storage system to quickly reach a balanced state during the charging and discharging process. Furthermore, when the initial SOC differs significantly, the current control algorithm may result in significantly different current distribution ratios to achieve consistency in the SOC of each battery cluster. Oscillations caused by external factors in the battery energy storage system can easily cause the battery energy storage system to overload when the current distribution ratios differ significantly.

[0006] Summary of the Invention

[0007] In view of this, the purpose of the present disclosure is to provide a current distribution method and an analog circuit, which can ensure that battery clusters of different capacities quickly reach equilibrium during operation, thereby increasing the stability and reliability of the battery energy storage system.

[0008] In a first aspect, an embodiment of the present disclosure provides a current distribution method, the method comprising:

[0009] 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;

[0010] Determining a current distribution target ratio for each battery cluster based on 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: a current remaining capacity of the battery cluster, a capacity setting critical value, and the distribution ratio constraint interval;

[0011] Current is distributed to each battery cluster according to the current distribution target ratio.

[0012] In an optional embodiment of the present disclosure, determining the allocation ratio constraint interval set for each battery cluster according to the total number of battery clusters in the plurality of battery clusters connected in parallel in the battery energy storage system includes:

[0013] When the system parameters of the battery energy storage system do not satisfy the current sharing condition, determining 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;

[0014] In an optional embodiment of the present disclosure, the method further includes:

[0015] When the system parameters of the battery energy storage system meet the current sharing condition, determining the current sharing ratio set for each battery cluster according to the total number of battery clusters;

[0016] The current is distributed to each battery cluster according to the current sharing ratio.

[0017] In an optional embodiment of the present disclosure, the current sharing condition includes one of the following items: the battery energy storage system is in a static operating 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, where 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.

[0018] In an optional embodiment of the present disclosure, determining the allocation ratio constraint interval set for each battery cluster according to the total number of battery clusters in the plurality of battery clusters connected in parallel in the battery energy storage system includes:

[0019] Obtaining a total number of battery clusters in 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, wherein the overload constraint ratio represents a preset ratio at which a current of the battery cluster exceeds a rated current range during charging or discharging;

[0020] 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.

[0021] In an optional embodiment of the present disclosure, 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:

[0022] Determining, based on the overload constraint ratio, a total upper limit value and a total lower limit value of the allocation ratio constraint of the battery energy storage system;

[0023] The upper and lower allocation ratio constraints set for each battery cluster are determined by using the ratios of the total of the allocation ratio constraint upper and lower limits to the total number of battery clusters.

[0024] In an optional embodiment of the present disclosure, the battery cluster parameters include 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;

[0025] The determining of the current distribution target ratio set for each battery cluster according to the battery cluster parameters includes:

[0026] 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;

[0027] 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.

[0028] In an optional embodiment of the present disclosure, 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:

[0029] 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 corresponding current distribution target ratio for each battery cluster.

[0030] In an optional embodiment of the present disclosure, 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:

[0031] 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 of each battery cluster.

[0032] In an optional embodiment of the present disclosure, determining the current distribution target ratio set for each battery cluster according to the battery cluster parameters further includes:

[0033] 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 distribution ratio to be adjusted that is newly set for the battery cluster and is not within the distribution ratio constraint interval, then determining a second current distribution ratio to be adjusted for each battery cluster based on the current remaining capacity of each battery cluster;

[0034] 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.

[0035] In an optional embodiment of the present disclosure, 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:

[0036] 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.

[0037] In an optional embodiment of the present disclosure, 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;

[0038] 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:

[0039] 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, determining the number of first battery clusters corresponding to 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 battery clusters whose second current distribution ratio to be adjusted is less than the lower limit of the distribution ratio constraint;

[0040] determining an allocation ratio adjustment value obtained by adjusting the second current allocation ratio to be adjusted, which is not within the allocation ratio constraint interval, to the closest allocation ratio constraint upper limit or allocation ratio constraint lower limit, 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;

[0041] The current distribution target ratio is determined according to the magnitude relationship between the total distribution ratio adjustment value and a preset distribution ratio adjustment threshold.

[0042] In an optional embodiment of the present disclosure, the allocation ratio adjustment value obtained by adjusting the second current allocation ratio to be adjusted that is less than the lower limit of the allocation ratio constraint to the lower limit of the allocation ratio constraint is a negative value, and the allocation ratio adjustment value obtained by adjusting the second current allocation ratio to be adjusted that is greater than the upper limit of the allocation ratio constraint to the upper limit of the allocation ratio constraint is a positive value.

[0043] In an optional embodiment of the present disclosure, 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:

[0044] 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 number of the second 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.

[0045] In an optional embodiment of the present disclosure, determining, based on the allocation ratio constraint lower limit, the allocation ratio adjustment total value, and the second number of battery clusters, to set a current distribution target ratio for the battery cluster whose second current distribution ratio to be adjusted is not within the allocation ratio constraint interval includes:

[0046] Determining an allocation ratio adjustment mean value by using a ratio between the total allocation ratio adjustment value and the number of the second battery clusters;

[0047] The current distribution target ratio is set for the battery cluster whose second current distribution ratio to be adjusted is not within the distribution ratio constraint interval by using the sum of the distribution ratio constraint lower limit and the distribution ratio adjustment mean value.

[0048] In an optional embodiment of the present disclosure, 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 further includes:

[0049] If the total value of the allocation ratio adjustment is less than or equal to 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 based on the allocation ratio constraint upper limit, the total value of the allocation ratio adjustment and the number of the first 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 based on the current remaining capacity of the battery cluster.

[0050] In an optional embodiment of the present disclosure, 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 further includes:

[0051] 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 ratios are not within the distribution ratio constraint interval;

[0052] Detecting the magnitude relationship between the recalculated total value of the allocation ratio adjustment and a preset allocation ratio adjustment threshold, and looping through 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:

[0053] If the recalculated total value of the allocation ratio adjustment is greater than a preset allocation ratio adjustment threshold, then re-determining, based on the allocation ratio constraint lower limit, the recalculated total value of the allocation ratio adjustment, and the number of the second battery clusters, a new current distribution target ratio is set for the battery clusters whose current distribution target ratio is not within the allocation ratio constraint interval;

[0054] If the recalculated total value of the allocation ratio adjustment is less than or equal to the 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 range based on the allocation ratio constraint upper limit, the recalculated total value of the allocation ratio adjustment and the first number of battery clusters.

[0055] In a second aspect, an embodiment of the present disclosure 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;

[0056] 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 and the second controlled branch are connected in parallel and then connected in series with the main relay, and the third relay is connected in parallel with the controlled current source.

[0057] The current distribution method and simulation circuit provided in the embodiments of the present disclosure first determine an allocation ratio constraint interval set for each battery cluster based on the total number of battery clusters in a plurality of parallel-connected battery clusters in a battery energy storage system. Then, a current distribution target ratio set for each battery cluster is determined based on battery cluster parameters, wherein the current distribution target ratio is within the allocation ratio constraint interval. The battery cluster parameters include at least one of the following items: the current remaining capacity of the battery cluster, a capacity setting threshold value, and the allocation ratio constraint interval. Finally, current is distributed to each battery cluster according to the current distribution target ratio.

[0058] Compared to current control algorithms in the prior art that only consider differences in state of charge or battery capacity to calculate the current distribution ratio set for each battery cluster, the embodiment of the present disclosure first defines a distribution ratio constraint interval set for each battery cluster. In this way, regardless of whether the initial state of charge of each battery cluster differs too much, the current distribution target ratio set for each battery cluster can be controlled to be within the distribution ratio constraint interval, avoiding excessive differences in the current distribution target ratios of each battery cluster when the initial state of charge differs too much. This not only enables the state of charge of each battery cluster to reach a consensus more quickly, but also avoids oscillations caused by external factors of the battery energy storage system, which can easily cause overload of the battery energy storage system when the current distribution ratios differ too much. A target current distribution ratio is then determined for each battery cluster based on the battery cluster parameters. The battery cluster parameters include at least one of the following: the current remaining capacity of the battery cluster, a capacity setting threshold, and a distribution ratio constraint interval. The DC converter in the battery energy storage system can accurately distribute current to each battery cluster according to the target current distribution ratio in this manner. Furthermore, the target current distribution ratio can be configured as a limit ratio within the distribution ratio constraint interval, allowing the DC converter to charge and discharge at an allowable limit current. This ensures that battery clusters of different capacities quickly reach equilibrium during operation, thereby increasing the stability and reliability of the battery energy storage system.

[0059] In order to make the above-mentioned objectives, features and advantages of the present disclosure more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0061] FIG1 is a flow chart of a current distribution method provided by an embodiment of the present disclosure;

[0062] FIG2 is a flow chart of another current distribution method provided by an embodiment of the present disclosure;

[0063] FIG3 is a schematic diagram of a first state of an analog circuit provided by an embodiment of the present disclosure;

[0064] FIG4 is a schematic diagram of a second state of an analog circuit provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0065] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. The components of the embodiments of the present disclosure generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present disclosure provided in the drawings is not intended to limit the scope of the disclosure for which protection is sought, but merely represents selected embodiments of the present disclosure. Based on the embodiments of the present disclosure, every other embodiment obtained by those skilled in the art without making creative work falls within the scope of protection of the present disclosure.

[0066] 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 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.

[0067] It should be understood that in the embodiments of the present disclosure, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent three situations: 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.

[0068] It should be understood that in the embodiments of the present disclosure, "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 based on A. Determining B based on A does not mean determining B based solely on A; B can also be determined based on A and / or other information.

[0069] In addition, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The components of the embodiments of the present disclosure generally described and shown in the drawings herein can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present disclosure provided in the drawings is not intended to limit the scope of the disclosure claimed for protection, but merely represents selected embodiments of the present disclosure. Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present disclosure.

[0070] First, battery energy storage systems consist of multiple battery clusters connected in parallel. Overcharging or over-discharging a battery cluster will cause irreversible capacity decay, and overcharging can also pose safety risks such as combustion or even explosion. To prevent overcharging or over-discharging of the battery cluster, a DC converter in the battery energy storage system is often used to precisely control the charging and discharging currents of the battery cluster.

[0071] However, current current control algorithms only consider differences in state of charge or battery capacity to calculate the current distribution ratio for each battery cluster. This requires at least one charge condition, one discharge condition, one cycle condition, or multiple cycles to achieve equilibrium, making it difficult for the battery energy storage system to quickly reach equilibrium during the charge and discharge process.

[0072] Moreover, when the initial state of charge differs greatly, such as in the case of partial overload or partial static conditions, 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 significant impact on the overall life, aging attenuation, availability, and depth of discharge of the battery energy storage system.

[0073] Furthermore, in order to achieve consistent state of charge of each battery cluster, the current control algorithm may result in significantly different current distribution ratios. Oscillations caused externally to the battery energy storage system can easily cause overload of the battery energy storage system when the current distribution ratios differ significantly.

[0074] Based on this, the embodiments of the present disclosure provide a current distribution method that can ensure that battery clusters of different capacities quickly reach equilibrium during operation, thereby increasing the stability and reliability of the battery energy storage system.

[0075] Please refer to Figure 1, which is a flow chart of a current distribution method provided by an embodiment of the present disclosure. As shown in Figure 1, the current distribution method provided by an embodiment of the present disclosure includes:

[0076] S101, determining an allocation ratio constraint interval set for each battery cluster based on the total number of battery clusters connected in parallel in a battery energy storage system;

[0077] S102, determining a current distribution target ratio to be set for each battery cluster based on 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 threshold, and a distribution ratio constraint interval;

[0078] S103 : Allocate current to each battery cluster according to the current distribution target ratio.

[0079] In step S101, the battery energy storage system includes multiple battery clusters connected in parallel and a DC converter. The battery cluster includes multiple 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 decay 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 near-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, the current distribution method shown in Figure 1 can be executed in the DC converter, and then the DC converter can achieve precise control of the charge and discharge current of the battery cluster to avoid overcharging or over-discharging of the battery cluster.

[0080] The total number of battery clusters refers to the total number of all battery clusters included in the battery energy storage system. Based on the total number of battery clusters, not only the current sharing ratio to be set for each battery cluster can be determined, but also the allocation ratio constraint range to be set for each battery cluster can be determined.

[0081] Specifically, step S101 includes:

[0082] Step S1011: Obtain 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. The overload constraint ratio represents a preset ratio at which the current of the battery cluster exceeds a rated current range during charging or discharging.

[0083] 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 by which the current of the battery cluster exceeds the rated current range during charging or discharging. In other words, the overload constraint ratio represents the preset proportion by which the current of the battery cluster during charging is allowed to exceed the first current specified value or the preset proportion by which the current of the battery cluster during discharging 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.

[0084] Exemplarily, the range of the overload constraint ratio is between 0 and 1. Specifically, the overload constraint ratio may be 0.1.

[0085] 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 to be set for each battery cluster.

[0086] 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.

[0087] Exemplarily, step S1012 specifically includes:

[0088] Step S1012a: Determine the total upper limit value and the total lower limit value of the allocation ratio constraint of the battery energy storage system according to the overload constraint ratio.

[0089] 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.

[0090] Step S1012b: Determine the upper and lower allocation ratio constraints set for each battery cluster by using the ratios of the total upper and lower allocation ratio constraints to the total number of battery clusters.

[0091] Here, the allocation ratio constraint interval of each battery cluster is the same.

[0092] 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 Indicates 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:

[0093] For example, according to the actual configuration parameters of the battery cluster, the limit can be set to 0.1.

[0094] The disclosed embodiments can adjust the overload constraint ratio in real time according to the actual operating conditions of the battery cluster, thereby flexibly setting the upper and lower limits of the allocation ratio constraint. Within the allocation ratio constraint range, 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 improved.

[0095] 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.

[0096] Here, the target current distribution ratio for each battery cluster is determined based on the battery cluster parameters, and this current distribution ratio is within the distribution ratio constraint interval. In other words, the target current distribution ratio for each battery cluster can be accurately determined based on the battery cluster parameters. By distributing current to each battery cluster according to this current distribution ratio, battery clusters of different capacities can achieve balance as quickly as possible during operation.

[0097] Furthermore, when the state of charge of each battery cluster differs greatly, the current distribution target ratios of each battery cluster are different, but the differences in the current distribution target ratios are guaranteed to be within the distribution ratio constraint range, so that the state of charge of each battery cluster can be consistent at a relatively fast speed while avoiding the problem of overload of the battery energy storage system due to external oscillation to the greatest extent. This can achieve balanced management and safe use, and further extend the service life of the battery clusters in the battery energy storage system.

[0098] 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 in 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.

[0099] Here, a capacity adjustment limit range is pre-set for the capacity setting critical value. 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 the range between 0 and the capacity setting critical value.

[0100] Step S102 specifically includes:

[0101] 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 threshold of each battery cluster.

[0102] 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.

[0103] For example, the first current distribution ratio to be adjusted of the i-th battery cluster is defined as I 1i,pct , the capacity setting critical value 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:

[0104] By using the above formula, the first current distribution ratio to be adjusted corresponding to each battery cluster can be calculated. According to the first current distribution ratio to be adjusted, the purpose of quickly distributing current to the battery cluster can be achieved.

[0105] Step 1022: Determine a current distribution target ratio based on whether the first current distribution ratio to be adjusted is within a distribution ratio constraint interval.

[0106] Step 1022 specifically includes:

[0107] Step 1022a: 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, determine the first current distribution ratio to be adjusted for each battery cluster within the distribution ratio constraint interval as the corresponding current distribution target ratio for each battery cluster.

[0108] Here, if the first current distribution ratio to be adjusted corresponding to each battery cluster is within the distribution ratio constraint range, 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.

[0109] 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 of each battery cluster.

[0110] That is, when it is detected that the first current distribution ratio to be adjusted corresponding to a battery cluster is not within the distribution ratio constraint interval, the capacity setting threshold value may be adjusted. For example, the capacity setting threshold value may be reduced, and then the first current distribution ratio to be adjusted set for each battery cluster is recalculated according to the calculation formula for the first current distribution ratio to be adjusted in step 1021 until the capacity setting threshold value is adjusted to the minimum value of the capacity adjustment limit range, such as the minimum value of the capacity adjustment limit range being 0. If, under the condition that the capacity setting threshold value is within the capacity adjustment limit range, it is detected that the first current distribution ratio to be adjusted corresponding to each battery cluster is within the distribution ratio constraint interval, then the currently determined first current distribution ratio to be adjusted may be determined as the target current distribution ratio.

[0111] Step 1023: If it is detected that the adjusted capacity setting critical value is not within the capacity adjustment limit range, and the first current distribution ratio to be adjusted that is newly set for the battery cluster is not within the distribution ratio constraint interval, then a second current distribution ratio to be adjusted that is set for each battery cluster is determined based on the current remaining capacity of each battery cluster;

[0112] Here, the current remaining capacities of all battery clusters are summed to obtain the current remaining capacity sum value. 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.

[0113] For example, 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:

[0114] The second current distribution ratio to be adjusted corresponding to each battery cluster can be calculated by the above formula. The purpose of quickly distributing current to the battery cluster can be achieved according to the second current distribution ratio to be adjusted.

[0115] 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.

[0116] Step 1024 specifically includes:

[0117] 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 constraint interval, determine the second current distribution ratio to be adjusted for each battery cluster within the distribution ratio constraint interval as the corresponding current distribution target ratio for each battery cluster.

[0118] Here, if the second current distribution ratio to be adjusted corresponding to each battery cluster is within the distribution ratio constraint range, 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.

[0119] 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, 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 are determined respectively.

[0120] The battery cluster parameters include an allocation ratio constraint interval, which includes an allocation ratio constraint upper limit and an allocation ratio constraint lower limit. The number of the first battery cluster can be determined based on the allocation ratio constraint upper limit, and the number of the second battery cluster can be determined based on the allocation ratio constraint lower limit.

[0121] 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.

[0122] Among them, the allocation ratio adjustment value obtained by adjusting the second current allocation ratio to be adjusted, which is less than the lower limit of the allocation ratio constraint, to the lower limit of the allocation ratio constraint is a negative value, and the allocation ratio adjustment value obtained by adjusting the second current allocation ratio to be adjusted, which is greater than the upper limit of the allocation ratio constraint, to the upper limit of the allocation ratio constraint is a positive value.

[0123] Here, the difference between the second current distribution ratio to be adjusted and the closest upper or lower distribution ratio constraint is calculated; this difference is the distribution ratio adjustment value. Specifically, this difference can be positive or negative. Subtracting the second current distribution ratio to be adjusted from the lower distribution ratio constraint, which is less than the lower distribution ratio constraint, results in a negative distribution ratio adjustment value; while subtracting the second current distribution ratio to be adjusted from the upper distribution ratio constraint, which is greater than the upper distribution ratio constraint, results in a positive distribution ratio adjustment value. The distribution ratio adjustment values ​​corresponding to all battery clusters whose second current distribution ratios to be adjusted are not within the distribution ratio constraint interval are summed to obtain a total distribution ratio adjustment value. Here, since distribution ratio adjustment values ​​can be both positive and negative, the calculated total distribution ratio adjustment value can be either positive or negative.

[0124] Step 1025 : Determine the current distribution target ratio according to the relationship between the total distribution ratio adjustment value and the preset distribution ratio adjustment threshold.

[0125] Step 1025 specifically includes:

[0126] Step 1025a: If the total value of the allocation ratio adjustment is less than or equal to the 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 lower limit, the total value of the allocation ratio adjustment, and the number of the second 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.

[0127] For example, the preset distribution ratio adjustment threshold may be 0. If, for the second current distribution ratios to be adjusted corresponding to the battery clusters calculated in step 1023, the second current distribution ratios to be adjusted corresponding to some or all of the battery clusters are not within the distribution ratio constraint interval, then the new calculation method involved in step 1025 is used to calculate the current distribution target ratio for the battery clusters whose second current distribution ratios to be adjusted are not within the distribution ratio constraint interval, while the calculation method involved in step 1023 is continued to be used to calculate the current distribution target ratio for the battery clusters whose second current distribution ratios to be adjusted are within the distribution ratio constraint interval.

[0128] Here, if the total value of the distribution ratio adjustment is less than or equal to the preset distribution ratio adjustment threshold, then for the battery cluster whose second current distribution ratio to be adjusted is not within the distribution ratio constraint interval, the current distribution target ratio is determined using the following calculation method:

[0129] The ratio between the total value of the allocation ratio adjustment and the number of the second battery clusters is used to determine the allocation ratio adjustment mean; and the sum of the allocation ratio constraint lower limit and the allocation ratio adjustment mean is used to determine the current allocation target ratio to be set for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval.

[0130] 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:

[0131] Step 1025b: If the total value of the allocation ratio adjustment is less than or equal to the 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 total value of the allocation ratio adjustment, and the number of the first 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.

[0132] Here, if the total value of the distribution ratio adjustment is less than or equal to the preset distribution ratio adjustment threshold, then for the battery cluster whose second current distribution ratio to be adjusted is not within the distribution ratio constraint interval, the current distribution target ratio is determined using the following calculation method:

[0133] The ratio between the total value of the allocation ratio adjustment and the number of the first battery clusters is used to determine the allocation ratio adjustment mean value; and the sum of the allocation ratio constraint upper limit and the allocation ratio adjustment mean value is used to determine the current allocation target ratio to be set for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval.

[0134] 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:

[0135] It should be noted that when the second current distribution ratio to be adjusted is not within the distribution ratio constraint interval, the current distribution target ratio is directly calculated through step 1025a or step 1025b according to the size relationship between the total distribution ratio adjustment value and the preset distribution ratio adjustment threshold.

[0136] 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;

[0137] Detect the size relationship between the recalculated total value of the allocation ratio adjustment 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.

[0138] The current distribution target ratio finally obtained in step 1025c can be guaranteed to be within the distribution ratio constraint range, and no further calculation is required through other methods.

[0139] 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, thereby enabling battery clusters of different capacities to reach balance as quickly as possible during operation.

[0140] In step S103, current is distributed to each battery cluster according to the target current distribution ratio determined in step S102. This allows current to be controlled within the constraints corresponding to the distribution ratio constraint interval, regardless of whether the initial states of charge of the battery clusters vary significantly. Current can be quickly distributed according to the maximum current output capacity of the distribution ratio constraint interval, allowing the battery clusters of the battery energy storage system to achieve equilibrium as quickly as possible within the allowable current range.

[0141] Please refer to FIG2 , which is a flow chart of another current distribution method provided by an embodiment of the present disclosure. As shown in FIG2 , the current distribution method provided by an embodiment of the present disclosure includes:

[0142] S201: If system parameters of the battery energy storage system do not satisfy a current sharing condition, determine an allocation ratio constraint interval set for each battery cluster based on the total number of battery clusters connected in parallel in the battery energy storage system;

[0143] S202, determining a current distribution target ratio to be set for each battery cluster based on 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 threshold, and a distribution ratio constraint interval; and distributing current to each battery cluster according to the current distribution target ratio;

[0144] 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.

[0145] The description of step S202 may refer to step S102 and will not be repeated here.

[0146] In step S201, the current sharing condition includes one of the following items: the battery energy storage system is in a static operating state, 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, where 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.

[0147] The battery management system (BMS) collects statistics on 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 system operating conditions. System operating conditions include static conditions, charging conditions, and discharging conditions. The BMS uses this data to determine whether the battery energy storage system parameters meet the current sharing requirements.

[0148] For example, in order to prevent excessive differences in the current remaining capacities of the battery clusters in the battery energy storage system, the preset difference threshold is selected to be a relatively small value, such as 1%.

[0149] Here, if the system parameters of the battery energy storage system do not meet the above-mentioned current sharing condition, the allocation ratio constraint interval set for each battery cluster is determined according to the total number of battery clusters connected in parallel in the battery energy storage system. The specific implementation method can be referred to step S101 and will not be repeated here.

[0150] 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.

[0151] That is to say, when the battery energy storage system is in a static operating 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. For example, the first preset ratio is 10%, the second preset ratio is 90%, and 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. The current sharing ratio set for each battery cluster is directly determined based on the total number of battery clusters.

[0152] Exemplarily, the current sharing ratio is determined by the following formula:

[0153] Where n represents the total number of battery clusters.

[0154] 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.

[0155] The disclosed embodiment first defines a distribution ratio constraint interval set for each battery cluster. This allows the current distribution target ratio set for each battery cluster to be controlled within the distribution ratio constraint interval, regardless of whether the initial states of charge of the battery clusters differ significantly. This prevents excessive differences in the current distribution target ratios of the battery clusters when the initial states of charge differ significantly. This not only allows the battery clusters to reach a consistent state of charge quickly, but also prevents oscillations caused by external factors of the battery energy storage system, which can easily cause overload of the battery energy storage system when the current distribution ratios differ significantly. The current distribution target ratio set for each battery cluster is then determined based on battery cluster parameters, which include at least one of the following: the current remaining capacity of the battery cluster, a capacity setting threshold, 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 this manner. The current distribution target ratio can be configured as a limit ratio within the distribution ratio constraint interval, allowing the DC converter to charge and discharge at an allowable limit current. This ensures that battery clusters of different capacities quickly reach equilibrium during operation, thereby increasing the stability and reliability of the battery energy storage system.

[0156] In related solutions, actual DC / DC circuits contain many high-speed switching transistors, making it difficult to obtain ideal results quickly through simulation, resulting in slow simulation speeds. This is especially true for series DC / DC circuits in battery energy storage systems. Due to the complex circuit structure of series DC / DC circuits, directly verifying the operation of the current distribution method will result in a low verification rate, making it difficult to obtain final verification results in a short period of time. Furthermore, since the internal resistance of an ideal current source is infinite and the internal resistance of an 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 calculation failures.

[0157] Based on this, an embodiment of the present disclosure provides an analog circuit for applying the current distribution method shown in Figure 1 or Figure 2. As shown in Figure 3 or Figure 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; 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 and the second controlled branch are connected in parallel 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.

[0158] Here, the above analog circuit is used for the battery cluster series DC / DC in the equivalent battery energy storage system.

[0159] The disclosed embodiment achieves decoupled control of voltage and current through an ideal current source, an ideal voltage source, and a relay, while avoiding the simulation calculation problems caused by the infinite / infinitesimal internal resistance of the ideal power source. The application of the current distribution algorithm shown in FIG1 or FIG2 in the above-mentioned analog circuit can realize the series DC / DC charging and discharging at an allowable limit current, and when the state of charge difference is too large, the current distribution target ratio difference of each battery cluster will not be 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 a series DC / DC with a relatively complex circuit structure in the prior art to verify the operation of the current distribution method in the disclosed embodiment, which makes it difficult to obtain the final verification result in a short time.

[0160] As shown in Figure 3, the analog circuit is in the first state, at which point no-load voltage regulation can be performed:

[0161] The DC / DC has a voltage regulation capability of 10V to 20V. When the main relay Ks is disconnected, the analog circuit equivalent series DC / DC is a series controlled voltage source with a default value of 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 analog circuit equivalent series DC / DC is manifested as the controlled voltage source 406 connected in series between the main relay Ks and the positive terminal of the battery. The voltage inside the main relay Ks is the battery voltage plus the voltage of the controlled voltage source 406. Since the ideal current source has infinite internal resistance and cannot 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.

[0162] As shown in Figure 4, the analog circuit is in the second state, where current regulation is possible:

[0163] When the voltage meets the closing conditions 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 of each battery cluster can be accurately controlled through the current distribution algorithm to achieve inter-cluster balancing requirements. At the same time, a positive and negative parallel controlled voltage source 406 is required on the DC bus. Its value is the minimum terminal voltage of all current cabinet clusters plus 20V. Since the terminal voltage difference between clusters does not exceed 10V when Δsoc is less than 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.

[0164] The disclosed embodiments address the high-speed computational requirements of the switching diodes in a real series DC / DC system by constructing an analog circuit. By constructing an ideal power supply, the external characteristics of the real series DC / DC system are reflected in the analog circuit. The ideal power supply and relays are connected in series and parallel to address the inherent limitations of an ideal current source (which cannot be open-circuited) and an ideal voltage source (which cannot be short-circuited). Furthermore, the analog circuit accelerates simulations, allowing for faster verification of the feasibility of current distribution methods. When applied in practice, current distribution methods verified by the analog circuit can improve the stability and reliability of battery energy storage systems.

[0165] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present disclosure, which are used to illustrate the technical solutions of the present disclosure, rather than to limit them. The scope of protection of the present disclosure is not limited thereto. Although the present disclosure has been described in detail with reference to the above-mentioned embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above-mentioned embodiments within the technical scope disclosed in the present disclosure, or replace some of the technical features therein with equivalents. Such modifications, changes, or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure, and should be included in the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims. Industrial Applicability

[0166] The present disclosure provides a current distribution method and analog circuit. The method includes: determining a distribution ratio constraint interval for each battery cluster based on the total number of battery clusters connected in parallel in a battery energy storage system; determining a current distribution target ratio for each battery cluster based on 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: the current remaining capacity of the battery cluster, a capacity setting threshold, and the distribution ratio constraint interval; and distributing current to each battery cluster according to the current distribution target ratio. The present disclosure can ensure that battery clusters of different capacities quickly reach equilibrium during operation, thereby increasing the stability and reliability of the battery energy storage system.

[0167] Furthermore, it is understood that the current distribution method and analog circuit disclosed herein are reproducible and can be used in a variety of industrial applications. For example, the current distribution method and analog circuit disclosed herein can be used in the field of circuit technology.

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 of the battery energy storage system and a total value of a lower limit constraint of an allocation ratio; 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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