Inter-cluster voltage-sharing control method, system and device of energy storage system and storage medium

Abstract

The invention provides an inter-cluster voltage-sharing control method, system and device of an energy storage system and a storage medium, and relates to the technical field of battery management systems and control. The method comprises the following steps executed by a controller: detecting the voltage of each battery cluster; if the voltage of each battery cluster meets the direct parallel connection condition, controlling the corresponding cluster switch to be closed so that all the battery clusters directly supply power in parallel; if the direct parallel connection condition is not met, controlling a change-over switch to connect a system bus to a voltage regulation loop containing a current-sharing impedance, and sequentially controlling cluster switches corresponding to the battery clusters to be closed according to a preset sequence, so that the battery clusters carry out energy transfer through the current-sharing impedance; and when the voltage of each battery cluster is judged to be balanced, the change-over switch is controlled to switch the system bus back to the power supply loop. By introducing a voltage regulation loop comprising current-sharing impedance and a set of step-by-step pre-equalization control logic, the problem of closing impact current caused by inter-cluster voltage difference when the multi-cluster parallel energy storage system is started or re-input is creatively solved.

Description

Technical Field

[0001] This invention relates to the field of battery management and control technology, and in particular to a method, system, device and storage medium for inter-cluster voltage equalization control of an energy storage system. Background Technology

[0002] With the increasing proportion of renewable energy and the growing demand for flexible regulation resources in power systems, electrochemical energy storage systems have been widely adopted. Large-scale energy storage systems typically consist of multiple battery clusters connected in parallel to provide the required voltage and capacity. Each battery cluster is equipped with an independent battery management system and cluster switch to achieve independent switching and control of the cluster. In actual operation, due to differences in the initial state of charge of each battery cluster, inconsistent operating history, or reactivation after maintenance, the voltage at each cluster terminal often differs when the system starts up or a cluster is reactivated.

[0003] If battery clusters with significant voltage differences are directly connected in parallel to the DC bus, a huge circulating inrush current will be generated the instant the cluster switch is closed. This current can easily exceed the withstand capability of the cluster switch, leading to contact erosion, adhesion, or even damage, seriously threatening system safety. To address this problem, existing technologies mainly employ two approaches: First, setting a strict closing voltage difference threshold, such as within 5V, allowing only clusters with very similar voltages to be connected in parallel. While this method is inexpensive, its applicability is limited, often resulting in some battery clusters being unable to be connected due to slightly higher or lower voltages, leading to low system capacity utilization. Second, adding a DC / DC converter at the output of each battery cluster to actively adjust the output voltage of each cluster to be consistent before connecting them in parallel. While this method effectively suppresses circulating current, it significantly increases the hardware complexity, cost, and losses of the system, resulting in poor economic efficiency.

[0004] Therefore, there is an urgent need in this field for a new voltage equalization control scheme that can effectively ensure the safety of multiple clusters in parallel and avoid inrush current, while also taking into account the system's economy and capacity utilization. Summary of the Invention

[0005] The purpose of this invention is to provide a method, system, device, and storage medium for inter-cluster pressure equalization control of an energy storage system, in order to solve the technical problems of low system capacity utilization and poor economic efficiency mentioned in the background art.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for inter-cluster pressure equalization control of an energy storage system is provided, wherein the method is performed by a controller in the following steps:

[0007] Detect the voltage of each battery cluster;

[0008] If the voltage of each battery cluster meets the conditions for direct parallel connection, then control the corresponding cluster switch to close so that all battery clusters can be directly connected in parallel to supply power;

[0009] If the direct parallel connection condition is not met, the control switch will connect the system bus to the voltage regulation circuit containing the current sharing impedance, and the cluster switches corresponding to each battery cluster will be closed in a predetermined order so that each battery cluster can transfer energy through the current sharing impedance.

[0010] Once it is determined that the voltage of each battery cluster is balanced, the switching switch is controlled to switch the system bus back to the power supply circuit.

[0011] In one possible implementation, the step of sequentially controlling the closing of the cluster switches corresponding to each battery cluster in a predetermined order specifically includes:

[0012] Based on the voltage of the battery clusters currently connected to the voltage regulation circuit, determine the next target battery cluster to be connected;

[0013] Control the cluster switch corresponding to the target battery cluster to close;

[0014] Monitor the electrical parameters that characterize the equalization process, and determine that the currently connected battery clusters have reached a temporary equalization state when the electrical parameters meet the first condition.

[0015] Repeat the aforementioned steps until all the battery clusters to be put into operation are connected to the voltage regulation circuit.

[0016] In one possible implementation, the step of determining the next target battery cluster to be connected based on the voltage of the battery clusters currently connected to the voltage regulation circuit specifically includes:

[0017] Sort all battery clusters by voltage and identify the unconnected battery clusters as target battery clusters in order from highest to lowest voltage or from lowest to highest voltage.

[0018] In one possible implementation, the step of monitoring the electrical parameters characterizing the equalization process specifically includes:

[0019] Monitor the equalization current flowing through the current sharing impedance or system bus; the first condition is met when the equalization current drops below a first current threshold.

[0020] In one possible implementation, the criteria for determining the voltage balance of each battery cluster include:

[0021] All battery clusters to be put into operation have been connected to the voltage regulation circuit, and the equalization current flowing through the current sharing impedance or system bus has dropped below the second current threshold.

[0022] In one possible implementation, the direct parallel condition is:

[0023] The difference between the highest and lowest voltages in all battery clusters is less than or equal to a preset allowable voltage difference threshold.

[0024] According to another aspect of the present invention, a battery management system is provided for an energy storage system, the energy storage system including a plurality of battery clusters, a cluster switch corresponding to each battery cluster, and a switching switch switchable between a power supply circuit and a voltage regulation circuit, the voltage regulation circuit including a current sharing impedance, the battery management system being configured to perform an inter-cluster voltage equalization control method for an energy storage system as described in any of the possible implementations above.

[0025] According to another aspect of the present invention, an inter-cluster pressure equalization control device for an energy storage system is provided, comprising:

[0026] The voltage detection module is used to obtain the voltage of each battery cluster;

[0027] The judgment module is used to determine whether the direct parallel connection condition is met based on the voltage.

[0028] The first control module is used to control the closing of all cluster switches when the direct parallel connection condition is met;

[0029] The second control module is used to control the switching switch to connect to the voltage regulation circuit when the direct parallel connection conditions are not met, to control the cluster switches to close in sequence to achieve inter-cluster equalization through the current sharing impedance, and to control the switching switch to switch back to the power supply circuit after equalization.

[0030] In one possible implementation, the current-sharing impedance is a fixed resistor, an adjustable resistor, or an electronic circuit with current-limiting functionality.

[0031] According to another aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored, which, when executed by a processor, implements the inter-cluster voltage equalization control method of the energy storage system as described in any of the above possible implementations.

[0032] The above-described one or more technical solutions in the embodiments of this application have at least one or more of the following technical effects:

[0033] This invention provides a method for inter-cluster voltage equalization control in an energy storage system. By introducing a voltage regulation loop containing current-sharing impedance and a set of step-by-step pre-equalization control logic, it creatively solves the problem of closing inrush current caused by inter-cluster voltage difference during startup or restart of a multi-cluster parallel energy storage system. Specifically, when the inter-cluster voltage difference is detected to be insufficient for direct parallel connection, the controller first switches the system bus from the power supply loop to the voltage regulation loop, putting the system into internal voltage equalization mode. Subsequently, according to a predetermined optimized sequence, each battery cluster is connected to the voltage regulation loop sequentially. During this process, the current-sharing impedance effectively limits the current generated during energy transfer between clusters, completely avoiding the instantaneous large current surge that may occur in traditional direct parallel connection methods. This greatly protects key components such as cluster switches and improves system reliability and safety. This solution only requires the addition of limited hardware such as switching switches and current-sharing impedance, and its cost is far lower than that of configuring a DC / DC converter for each cluster, demonstrating significant economic advantages. At the same time, it breaks through the limitations of the strict voltage threshold method, enabling battery clusters at different voltage states to be safely and gradually incorporated into the system, which greatly improves the utilization rate of battery clusters and the overall available capacity of the system.

[0034] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0035] Figure 1 This is a schematic flowchart of an inter-cluster pressure equalization control method for an energy storage system according to an exemplary embodiment.

[0036] Figure 2 This is a schematic diagram of an energy storage system architecture provided according to an exemplary embodiment. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0038] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of systems and methods consistent with some aspects of the invention as detailed in the appended claims.

[0039] Figure 1 This is a flowchart of an inter-cluster pressure equalization control method for an energy storage system according to an exemplary embodiment, as shown below. Figure 1 As shown, the controller performs the following steps:

[0040] In step S100, the voltage of each battery cluster is detected; this step is the basis for the decision to execute subsequent control logic, and the specific implementation process is as follows:

[0041] When the controller needs to perform inter-cluster parallel operation, such as when the system starts up or receives a command to add a new battery cluster, it sends a voltage detection command to the battery management system of each battery cluster through the communication bus in the system; the communication bus can be a controller area network bus, a serial communication bus, or an Ethernet, etc.

[0042] Upon receiving the voltage detection command, the battery management system of each battery cluster measures the open-circuit voltage at the output terminal of that battery cluster using its internal voltage sampling circuit. This voltage sampling circuit typically includes a voltage divider resistor network, a filter circuit, and an analog-to-digital converter to obtain a high-precision DC voltage digital signal. Each battery management system encapsulates the measured voltage data for its cluster into a data frame and sends it back to the controller via the communication bus.

[0043] The controller receives and parses voltage data from each battery management system. To ensure data integrity and timeliness for subsequent control, the controller can set a preset response waiting time window. For battery clusters that successfully report voltage data within this time window, their voltage values ​​are recorded and used for subsequent calculations and judgments; for battery clusters that fail to report valid voltage data within this time window, the controller can mark them as having a communication anomaly and exclude them from the parallel operation sequence in the current control cycle, or trigger a fault handling process.

[0044] Through the above process, the controller obtains the independent open-circuit voltage values ​​of all battery clusters to be connected in parallel at the current moment; these voltage data will be directly used in the next step to determine whether the direct parallel connection conditions are met.

[0045] In step S200, if the voltage of each battery cluster meets the direct parallel connection condition, the corresponding cluster switch is closed to enable all battery clusters to be directly connected in parallel for power supply. In this step, the controller performs the judgment of the parallel connection condition and the corresponding control operation based on the voltage of each battery cluster obtained in step S100.

[0046] First, the controller determines whether the voltage of each battery cluster meets the conditions for direct parallel connection. For example, the conditions for direct parallel connection are:

[0047] The difference between the highest and lowest voltages in all battery clusters is less than or equal to a preset allowable voltage difference threshold.

[0048] Specifically, the controller calculates the highest voltage among all the battery clusters to be added. With the lowest voltage And calculate the difference between the two. ,Right now The controller will calculate the difference. With a pre-set direct parallel voltage difference threshold stored in its memory Compare them. If the relation is satisfied... If so, it is determined that the direct parallel connection condition is met.

[0049] The direct parallel voltage difference threshold The determination is based on the electrical safety parameters and system circuit parameters of the cluster switch. Specifically, the determination method includes: obtaining the maximum instantaneous inrush current that the cluster switch can safely withstand. This value is obtained from the datasheet or performance test results of the cluster switch; the equivalent internal resistance of the DC bus circuit of the energy storage system is obtained or estimated. This value includes line resistance, connection resistance, etc., and can be obtained from the system configuration parameter table or by measurement; then the threshold is calculated according to Ohm's law. ,Right now For example, if It is 500A. If it is 0.01Ω, then Set to 5V. The threshold value... It can be written to the controller's non-volatile memory during system debugging or parameter tuning.

[0050] When the direct parallel connection conditions are met, the controller executes a direct parallel power supply operation. The controller first controls the switching switch to be in or switched to the position connecting the system bus to the power supply circuit. Subsequently, the controller issues closing commands to the cluster switches corresponding to all battery clusters to be connected. These closing commands can be issued simultaneously or sequentially at very short time intervals, for example, less than 10 milliseconds, so that the DC output terminals of each battery cluster are connected in parallel to the system bus through their corresponding closed cluster switches, and together supply power to the load or grid through the power supply circuit.

[0051] Assuming there are four battery clusters to be connected, their open-circuit voltages, detected in step S100, are 100V, 101V, 102V, and 103V respectively. The controller calculates... ,but Assuming the system is pre-set... .because The conditions for direct parallel connection are met. The controller then controls the switching switch to connect to the power supply circuit and controls the cluster switches corresponding to the four battery clusters to close, so that the four battery clusters are directly connected in parallel to supply power to the load.

[0052] At this point, the system has completed rapid parallel connection and entered normal charging and discharging operation mode.

[0053] In step S300, if the direct parallel connection condition is not met, the switching switch is controlled to connect the system bus to a voltage regulating circuit containing a current-sharing impedance, and the cluster switches corresponding to each battery cluster are closed sequentially according to a predetermined order, so that each battery cluster transfers energy through the current-sharing impedance; specifically, when the controller determines that the direct parallel connection condition described in step S200 is not met, that is, when the maximum difference between the voltages of each battery cluster is... Greater than the direct parallel voltage difference threshold At this time, the following control process is executed to achieve safe pre-balancing:

[0054] First, the controller ensures that the cluster switches corresponding to all battery clusters to be connected are in the open state. Then, the controller sends a control command to the switching switch, causing it to switch from being connected to the power supply circuit to connecting the system bus to the voltage regulating circuit. The voltage regulating circuit includes a pre-set current-sharing impedance. This current-sharing impedance limits the circulating current caused by inter-cluster voltage differences during subsequent battery cluster connection. The current-sharing impedance can be a power resistor, an inductor, or a combination of a resistor and an inductor.

[0055] After connecting the system bus to the voltage regulation circuit, the controller determines the closing sequence of each cluster switch according to a predetermined optimization logic based on the voltage values ​​of each battery cluster obtained in step S100. A preferred embodiment is to close the cluster switches sequentially in descending order of voltage. That is, first close the cluster switch corresponding to the battery cluster with the highest voltage, then close the cluster switch corresponding to the battery cluster with the second highest voltage, and so on, finally closing the cluster switch corresponding to the battery cluster with the lowest voltage.

[0056] The controller sends closing commands to each cluster of switches in the order determined above at certain time intervals, for example, at intervals of 1 second to several seconds. The specific time can be set based on the power and heat capacity of the current sharing impedance.

[0057] When the first cluster switch, i.e. the cluster switch with the highest voltage, is closed, the voltage of that battery cluster is applied to the voltage regulation circuit.

[0058] When the second cluster switch is closed, due to the voltage difference between the two battery clusters, current will flow from the higher-voltage cluster to the lower-voltage cluster through the current-sharing impedance. The core function of the current-sharing impedance is demonstrated at this moment: it limits the amplitude of this energy transfer current to a safe and acceptable range, thereby completely avoiding any potentially harmful surge current that might occur at the moment of closure.

[0059] Subsequently, with each subsequent cluster switch closed, the newly connected battery cluster will exchange charge and redistribute energy with other battery clusters already on the voltage regulation circuit through the current sharing impedance, and its current is always limited by this impedance.

[0060] During the aforementioned step-by-step closing process, energy continuously transfers from the high-voltage battery cluster to the low-voltage battery cluster through the current-sharing impedance. The voltage of the high-voltage cluster gradually decreases, while the voltage of the low-voltage cluster gradually increases. During this process, the controller continuously or periodically repeats the voltage detection in step S100 to monitor the voltage changes of all battery clusters connected to the voltage regulation circuit in real time.

[0061] At this point, the system enters a controlled and safe inter-cluster voltage pre-equalization phase, preparing for the subsequent switchback to normal operating mode.

[0062] In step S400, after determining that the voltage of each battery cluster is balanced, the switching switch is controlled to switch the system bus back to the power supply circuit. The controller's determination of voltage balance is based on the real-time voltage data of all battery clusters connected to the voltage regulation circuit, which are continuously or periodically detected during the pre-balancing process in step S300. Specifically, the determination condition is: calculating the maximum difference between the voltages of all currently closed cluster switches. This difference is then compared with an equilibrium completion threshold. Compare them. If satisfied... If the voltage of each battery cluster is equalized, it is determined that the voltage of each battery cluster is equalized.

[0063] The threshold for determining the completion of the equalization process It can be set to the threshold of the direct parallel voltage difference in step S200. The same value is used to ensure safety when switching back to the power supply circuit; it can also be set to a value higher than... Smaller values ​​are used to achieve a more precise balancing effect, further improving the stability of subsequent parallel operation. It is also preset in the controller's storage unit.

[0064] Once the equalization condition is met, the controller sends a control command to the switching switch, causing it to switch back from the position connected to the voltage regulating circuit to the position connected to the power supply circuit. This operation removes the voltage regulating circuit, which includes the current sharing impedance, from the system's main energy path.

[0065] At this point, all battery clusters are connected in parallel to the system bus via their corresponding closed cluster switches, and this bus is directly connected to the power supply circuit. The system voltage is stable, and there is no harmful voltage difference between clusters. The controller then sends a parallel readiness signal to the upstream energy management system or converter, and the system enters normal charging or discharging operation mode.

[0066] By introducing a voltage regulation loop incorporating current-sharing impedance and a set of step-by-step pre-equalization control logic, this solution creatively addresses the problem of inrush current during startup or reactivation of multi-cluster parallel energy storage systems caused by inter-cluster voltage differences. Specifically, when the inter-cluster voltage difference is detected to be insufficient for direct parallel connection, the controller first switches the system bus from the power supply loop to the voltage regulation loop, putting the system into internal voltage equalization mode. Subsequently, each battery cluster is connected to the voltage regulation loop sequentially according to a predetermined optimized order. During this process, the current-sharing impedance effectively limits the current generated during energy transfer between clusters, completely avoiding the instantaneous large current surge that may occur in traditional direct parallel connection methods. This greatly protects key components such as cluster switches and improves system reliability and safety. This solution requires only the addition of limited hardware such as switching switches and current-sharing impedance, and its cost is far lower than that of configuring a DC / DC converter for each cluster, resulting in significant economic benefits. Furthermore, it overcomes the limitations of the strict voltage threshold method, allowing battery clusters at different voltage states to be safely and gradually integrated into the system, significantly improving the utilization rate of battery clusters and the overall available capacity of the system.

[0067] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0068] In an exemplary embodiment, the step of sequentially controlling the closing of the cluster switches corresponding to each battery cluster in a predetermined order specifically includes:

[0069] Based on the voltage of the battery clusters currently connected to the voltage regulating circuit, the next target battery cluster to be connected is determined. Specifically, the controller calculates the average voltage or voltage range of the battery clusters currently connected to the voltage regulating circuit with their cluster switches closed. Then, from all the battery clusters not yet connected, the battery cluster whose open-circuit voltage is closest to the average voltage or voltage range is selected and designated as the target battery cluster. This strategy aims to minimize the inrush current caused by the voltage difference during the next closing operation.

[0070] The cluster switch corresponding to the target battery cluster is closed. At this time, due to the voltage difference between the newly connected target battery cluster and the already connected battery cluster, the current will be transferred through the current sharing impedance, and the current value is effectively limited by the current sharing impedance.

[0071] The system monitors electrical parameters characterizing the equalization process, and determines that the currently connected battery clusters have reached a temporary equalization state when the electrical parameters meet a first condition. In a preferred embodiment, the step of monitoring electrical parameters characterizing the equalization process specifically includes: monitoring the equalization current flowing through the current sharing impedance or the system bus; the first condition being met means that the equalization current drops below a first current threshold. The controller continuously or periodically samples the current value, and when it detects that the current value has decreased and remains stably below a preset first current threshold, it determines that all currently connected battery clusters in the voltage regulation circuit have reached a temporary equalization state. The first current threshold is set according to the system accuracy requirements and the thermal capacity of the current sharing impedance.

[0072] Repeat the aforementioned steps until all battery clusters requiring operation are connected to the voltage regulation circuit. Specifically, after each temporary equalization state is reached, the voltage of the unconnected battery clusters is reassessed, and the next target battery cluster is dynamically selected and connected until all battery clusters requiring operation are connected to the voltage regulation circuit, completing the global pre-equalization process.

[0073] Through the closed-loop control described above, the system can adaptively select the optimal connection sequence and achieve voltage convergence of all battery clusters in a safe, step-by-step current manner, providing a reliable guarantee for the final switch to the power supply circuit.

[0074] In an exemplary embodiment, the step of determining the next target battery cluster to be connected based on the voltage of the battery clusters currently connected to the voltage regulation circuit specifically includes:

[0075] The voltages of all battery clusters are sorted, and the unconnected battery clusters are identified as target battery clusters in order from highest to lowest voltage or vice versa. In one implementation, the controller executes a descending-order closing strategy from highest to lowest voltage. That is, among all battery clusters, the battery cluster with the highest voltage value is first identified as the target battery cluster; after its corresponding cluster switch is closed and the subsequent temporary equalization conditions are met, the battery cluster with the second highest voltage value is identified as the next target battery cluster; and so on, until the battery cluster with the lowest voltage value is finally identified as the target battery cluster and connected to the circuit.

[0076] In another implementation, the controller executes an ascending-order closing strategy from the lowest voltage to the highest voltage. The order in which it determines the target battery clusters is the reverse of the aforementioned descending-order strategy.

[0077] Regardless of which fixed sorting strategy is adopted, the core objective is to provide a clear, predictable, and closed-loop sequence that does not require recalculation of comparisons during the process, thus simplifying the control logic. Prioritizing a sequence from highest to lowest voltage has the advantage of establishing a higher system bus voltage at the initial stage of equilibration, which is beneficial for the consistency of subsequent energy transfer directions.

[0078] This fixed sorting strategy is a simplified and effective implementation of the dynamic selection of the closest cluster based on the voltage of the currently connected clusters.

[0079] In an exemplary embodiment, the criteria for determining the voltage balance of each battery cluster include:

[0080] All battery clusters requiring operation have been connected to the voltage regulation circuit, and the equalization current flowing through the current sharing impedance or system bus has decreased below the second current threshold. Specifically, all battery clusters requiring operation have been successfully connected to the voltage regulation circuit, meaning their corresponding cluster switches are all in the closed state, ensuring that all units participating in energy exchange are in place.

[0081] Based on the conditions for connection, the controller monitors the current flowing through the current sharing impedance or system bus, i.e., the equalization current. When the equalization current is detected to be continuously decreasing and eventually stabilized below a preset second current threshold, the voltage equalization is determined to be complete.

[0082] The second current threshold is a current threshold used to determine whether the system has reached a macroscopic steady state. Its value is usually less than or equal to the first current threshold used to determine the temporary equilibrium state. For example, the first current threshold can be set to 2A, while the second current threshold can be set to 1A or 0.5A. The setting of the second current threshold takes into account the system measurement noise, residual small circulating current, and equilibrium accuracy requirements.

[0083] When all battery clusters are connected, if there is still a significant voltage difference between the clusters, the equalization current will remain at a high level. As energy continues to transfer, the voltage difference gradually decreases, and the equalization current also decreases. When the current decreases to below the second current threshold, it indicates that the voltage difference between the clusters has been reduced to an acceptable range, and the system reaches an overall balanced state.

[0084] This dual judgment criterion provides a reliable and direct criterion for equalization completion. It indirectly and effectively reflects the degree of voltage equalization by monitoring the intensity of energy transfer activities, avoiding the synchronization error problem that may exist if relying solely on voltage sampling, and making the control logic more robust.

[0085] In an exemplary embodiment, the present invention also provides a battery management system for an energy storage system, the energy storage system including a plurality of battery clusters, a cluster switch corresponding to each battery cluster, and a switching switch switchable between a power supply circuit and a voltage regulation circuit, the voltage regulation circuit including a current sharing impedance, the battery management system being configured to perform an inter-cluster voltage equalization control method for an energy storage system as described in any of the exemplary embodiments above.

[0086] The following section elaborates on the system and method using specific application scenarios. (Refer to...) Figure 2 The diagram shows an energy storage system architecture comprising multiple battery clusters connected in parallel, illustrated as clusters 1 to 4. The positive and negative outputs of each battery cluster are connected to a common DC bus via a controlled cluster switch. Figure 2 The cluster switches K1 to K4 shown can be relays or contactors. Compared with traditional energy storage systems, this energy storage system adds a voltage regulating circuit consisting of a switching switch K5 and a current sharing impedance R; wherein, the switching switch K5 is a single-pole double-throw switch with two stable positions. Figure 2 In the diagram, position B1 is used to connect the DC bus to the power supply circuit, i.e., to an external converter or load; position B2 is used to connect the DC bus to the voltage regulation circuit, which includes the current sharing impedance R; the current sharing impedance R is typically a power resistor whose resistance value is selected by design to limit inter-cluster circulating current during the pre-equalization process and ensure that the inrush current is within a safe range.

[0087] The battery management system, as the core controller, is communicatively connected to cluster switches K1 to K4, switching switch K5, and the monitoring unit inside each battery cluster. It stores a control program and is configured to execute the following control logic.

[0088] In a low-voltage scenario that satisfies the direct parallel connection condition, it is assumed that the open-circuit voltages of the four battery clusters detected before power-on are 100V, 101V, 102V, and 103V, respectively.

[0089] BMS calculates the maximum voltage minimum voltage Pressure difference The system's preset direct parallel voltage difference threshold. The threshold is 5V, which is based on the withstand current of the cluster switch. and the equivalent internal resistance of the system's DC circuit Calculation determined.

[0090] because This satisfies the conditions for direct parallel connection. The battery management system executes a rapid power-on process: first, it controls the switching switch K5 to close to position B1, connecting the power supply circuit. Then, it controls all cluster switches K1, K2, K3, and K4 to close, either simultaneously or sequentially at very short intervals. Finally, all battery clusters are directly connected in parallel, jointly supplying power to the load through the power supply circuit. The system operates in the same way as traditional architectures, offering high efficiency and speed.

[0091] In a high-voltage differential scenario requiring pre-balancing, assuming the open-circuit voltages of the four battery clusters are detected as 100V, 110V, 120V, and 130V respectively before power-on, the battery management system calculates... .because If the conditions for direct parallel connection are not met, the pre-balancing process must be entered.

[0092] The battery management system first ensures that all cluster switches are in the off state. Then, it controls the changeover switch K5 to switch to position B2, connecting the DC bus to a voltage regulation circuit that includes a current-sharing impedance R (e.g., R = 10Ω).

[0093] First, the battery management system identifies the battery cluster 4 (130V) with the highest voltage as the target and controls its cluster switch K4 to close. At this time, the bus voltage is approximately 130V.

[0094] Then, the battery management system identifies the second-highest voltage battery cluster 3 (120V) as the target and controls its cluster switch K3 to close. At the moment of closing, due to the 10V voltage difference, the inrush current is limited. The battery management system monitors the bus current.

[0095] As energy is transferred from battery cluster 4 to battery cluster 3, the current decreases. When the current remains below a first current threshold (e.g., 2A), it is determined that battery cluster 3 and battery cluster 4 have reached a temporary equilibrium, assuming that their voltages approach 125V.

[0096] Next, the battery management system selects battery cluster 2 (approximately 125V) from the remaining unconnected clusters (cluster 2: 110V, cluster 1: 100V) as the next target, controlling K2 to close. The inrush current is approximately... .

[0097] Then, wait for the current to decay to below the first current threshold (2A) again, and determine that battery cluster 2 and the connected clusters have reached a temporary equilibrium.

[0098] Finally, the battery management system controls the closing of switch K1 of the last remaining battery cluster 1 (100V), completing the connection of all battery clusters and performing final global balancing.

[0099] The battery management system continuously monitors the system. When all cluster switches are closed and the equalization current flowing through the current sharing impedance decreases and stabilizes below the second current threshold, it determines that voltage equalization is complete. Subsequently, the battery management system controls the switching switch K5 to switch from position B2 back to position B1. All battery clusters are safely connected in parallel with basically the same voltage, and the system restores its ability to supply power to the outside through the power supply circuit.

[0100] Alternatively, in addition to the dynamic selection strategy described above, a fixed sequence can also be adopted, such as strictly closing cluster switches in order of voltage from high to low or from low to high.

[0101] Understandable, regarding Key parameters such as the first and second current thresholds must be determined during the design phase and pre-stored in the battery management system based on the specific system hardware specifications and performance requirements.

[0102] The core idea of ​​the above method and system architecture is to achieve safe pre-parallel connection of multiple DC power supplies through switchable current limiting loops. It is applicable to various fields of parallel connection of multiple battery packs, such as electric vehicles, drones, and electric motorcycles.

[0103] In an exemplary embodiment, the present invention also provides an inter-cluster voltage equalization control device for an energy storage system. This device can be integrated into the battery management system of the energy storage system or a separate system controller, and is used to execute the aforementioned inter-cluster voltage equalization control method for the energy storage system. (Refer to...) Figure 2 The energy storage system architecture shown includes the following functional modules logically:

[0104] The voltage detection module is used to acquire the voltage of each battery cluster. Specifically, the module sends instructions to the local monitoring unit of each battery cluster through the system communication bus and receives its feedback, thereby acquiring the terminal voltage value of each battery cluster when the cluster switch is off.

[0105] The judgment module is used to determine whether the direct parallel connection condition is met based on the voltage; this module is connected to the voltage detection module and is used to calculate the difference between the maximum and minimum values ​​of the voltages of all battery clusters to be added. and will The direct parallel voltage difference threshold pre-stored in the device The comparison is performed, and corresponding control decision signals are generated based on the comparison results.

[0106] The first control module is used to control all cluster switches to close when the direct parallel connection conditions are met. This module is connected to the judgment module and is used to generate an instruction to control the switching switch K5 to switch to or remain in the position connected to the power supply circuit B1 when the judgment module determines that the direct parallel connection conditions are met. Subsequently, an instruction is generated to control the cluster switches corresponding to all battery clusters to be put into operation to close, so as to realize the direct parallel power supply of all battery clusters.

[0107] The second control module is used to control the switching switch to connect to the voltage regulation circuit when the direct parallel connection condition is not met, sequentially control the cluster switches to close to achieve inter-cluster equalization through current sharing impedance, and control the switching switch to switch back to the power supply circuit after equalization. This module is also connected to the judgment module and is used to execute the following when the judgment module determines that the direct parallel connection condition is not met:

[0108] The generated command controls the switching switch K5 to disconnect the system bus from the power supply circuit and connect it to the voltage regulating circuit B2, which includes the current sharing impedance R.

[0109] According to a predetermined order, such as sorting by voltage from high to low, instructions are generated sequentially to control the closing of the cluster switches corresponding to each battery cluster, so that each battery cluster can transfer energy and balance voltage through the current sharing impedance.

[0110] During the balancing process, the balancing state is determined based on the monitored electrical parameters;

[0111] Once it is determined that the voltage of each battery cluster is balanced, a command is generated to control the switching switch K5 to switch back to the position connected to the power supply circuit B1.

[0112] The above modules work together to achieve safe and automatic voltage equalization control of multi-cluster parallel energy storage systems.

[0113] Optionally, the current-sharing impedance can be a fixed resistor, an adjustable resistor, or an electronic circuit with current-limiting function. Specifically, the current-sharing impedance is the core component for realizing the current-limiting function, and its specific implementation is not limited to a single type.

[0114] In one embodiment, the current-sharing impedance can be a power resistor with a fixed resistance value, selected based on the system's maximum allowable equalization current and the expected maximum voltage difference. This solution is simple in structure, low in cost, and highly reliable.

[0115] In another embodiment, the current-equalizing impedance can be an adjustable resistor, for example, achieved by switching different combinations of resistor values ​​using a digital potentiometer or relay. This allows the controller to dynamically adjust the impedance value based on the real-time voltage difference, thereby providing stronger current limiting during the initial stage of equalization when the voltage difference is large, and reducing the impedance during the final stage of equalization when the voltage difference is small to reduce equalization time and losses, achieving better equalization performance.

[0116] In another embodiment, the current-sharing impedance can be an electronic circuit with active current-limiting functionality, such as a constant current source circuit composed of a power MOSFET operating in the linear region, or a controlled current source or absorber. This circuit can precisely limit the equalization current to a preset constant safety value, providing a smoother and more controllable equalization process.

[0117] All of the above implementation methods can achieve the core objective of this invention, namely, to provide the necessary impedance to limit the current within a safe range when the battery cluster transfers energy through the voltage regulation circuit. Those skilled in the art can choose the appropriate method based on the specific application's requirements for cost, control complexity, and performance.

[0118] In an exemplary embodiment, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the inter-cluster voltage equalization control method for the energy storage system as described in any of the exemplary embodiments above. Optionally, the storage medium is a non-transitory computer-readable storage medium, such as a ROM (Read-Only Memory), RAM (Random Access Memory), CD-ROM (Compact Disc Read-Only Memory), magnetic tape, floppy disk, and optical data storage device, etc.

[0119] In an exemplary embodiment, a computer program product is also provided, which includes computer program code stored in a computer-readable storage medium. A processor of a computer device reads the computer program code from the computer-readable storage medium and executes the computer program code, causing the computer device to perform the operations performed in the above-described inter-cluster voltage equalization control method for the energy storage system.

[0120] Any aspects of this invention not described in detail are well-known to those skilled in the art.

[0121] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for inter-cluster pressure equalization control in an energy storage system, characterized in that, The controller performs the following steps: Detect the voltage of each battery cluster; If the voltage of each battery cluster meets the conditions for direct parallel connection, then control the corresponding cluster switch to close so that all battery clusters can be directly connected in parallel to supply power; If the direct parallel connection condition is not met, the control switch will connect the system bus to the voltage regulation circuit containing the current sharing impedance, and the cluster switches corresponding to each battery cluster will be closed in a predetermined order so that each battery cluster can transfer energy through the current sharing impedance. Once it is determined that the voltage of each battery cluster is balanced, the switching switch is controlled to switch the system bus back to the power supply circuit.

2. The inter-cluster pressure equalization control method for an energy storage system according to claim 1, characterized in that, The step of controlling the cluster switches corresponding to each battery cluster to close in a predetermined order specifically includes: Based on the voltage of the battery clusters currently connected to the voltage regulation circuit, determine the next target battery cluster to be connected; Control the cluster switch corresponding to the target battery cluster to close; Monitor the electrical parameters that characterize the equalization process, and determine that the currently connected battery clusters have reached a temporary equalization state when the electrical parameters meet the first condition. Repeat the aforementioned steps until all battery clusters to be put into operation are connected to the voltage regulation circuit.

3. The inter-cluster pressure equalization control method for an energy storage system according to claim 2, characterized in that, The step of determining the next target battery cluster to be connected based on the voltage of the battery clusters currently connected to the voltage regulation circuit specifically includes: Sort all battery clusters by voltage and identify the unconnected battery clusters as target battery clusters in order from highest to lowest voltage or from lowest to highest voltage.

4. The inter-cluster pressure equalization control method for an energy storage system according to claim 2, characterized in that, The steps for monitoring and characterizing the electrical parameters of the equilibrium process specifically include: Monitor the equalization current flowing through the current sharing impedance or system bus; the first condition is met when the equalization current drops below a first current threshold.

5. The inter-cluster pressure equalization control method for an energy storage system according to claim 1, characterized in that, The criteria for determining whether the voltage of each battery cluster is balanced include: All battery clusters to be put into operation have been connected to the voltage regulation circuit, and the equalization current flowing through the current sharing impedance or system bus has dropped below the second current threshold.

6. The inter-cluster pressure equalization control method for an energy storage system according to claim 1, characterized in that, The direct parallel connection condition is: The difference between the highest and lowest voltages in all battery clusters is less than or equal to a preset allowable voltage difference threshold.

7. A battery management system for an energy storage system, the energy storage system comprising a plurality of battery clusters, a cluster switch corresponding to each battery cluster, and a switching switch switchable between a power supply circuit and a voltage regulation circuit, the voltage regulation circuit including a current sharing impedance, characterized in that, The battery management system is configured to perform the inter-cluster voltage equalization control method of the energy storage system as described in any one of claims 1 to 6.

8. A cluster-to-cluster pressure equalization control device for an energy storage system, characterized in that, include: The voltage detection module is used to obtain the voltage of each battery cluster; The judgment module is used to determine whether the direct parallel connection condition is met based on the voltage. The first control module is used to control the closing of all cluster switches when the direct parallel connection condition is met; The second control module is used to control the switching switch to connect to the voltage regulation circuit when the direct parallel connection conditions are not met, to control the cluster switches to close in sequence to achieve inter-cluster equalization through the current sharing impedance, and to control the switching switch to switch back to the power supply circuit after equalization.

9. The inter-cluster pressure equalization control device for the energy storage system according to claim 8, characterized in that, The current-equalizing impedance is a fixed resistor, an adjustable resistor, or an electronic circuit with current-limiting function.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the inter-cluster pressure equalization control method for the energy storage system as described in any one of claims 1 to 6.

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