Energy storage system based on retired battery pack

Abstract

The present disclosure provides an energy storage system based on retired battery packs, comprising: a plurality of battery clusters connected in parallel, each of the plurality of battery clusters comprising a plurality of battery packs connected in series, or each of the plurality of battery clusters comprising one or more battery packs and a first voltage converter, the first voltage converter is used for controlling one or more of voltage, current and power of the one or more battery packs; the battery management system is electrically connected with the plurality of battery clusters and is used for controlling the plurality of battery clusters to charge and discharge; wherein the battery management system performs program updating through the controller local area network bus so as to update the original code of the battery pack into the energy storage code of the energy storage system. According to the energy storage system provided by the invention, the complexity of the retired battery pack in the secondary application process is remarkably reduced, and meanwhile, related technical limitations in the secondary application process are also avoided.

Description

Technical Field

[0001] The present disclosure relates to the field of power batteries, and in particular to an energy storage system based on retired battery packs. Background Art

[0002] Power battery packs retired from original equipment (such as new energy vehicles, electric ships, etc.) can be used for a second time in places such as energy storage systems that have relatively low requirements for power battery packs, which is called second-life use. The usual method is to disassemble the retired power battery packs and then reassemble them into new battery packs for use.

[0003] However, the above method is relatively cumbersome in practical application and there are a lot of technical challenges and safety issues. Summary of the invention

[0004] In view of this, the present disclosure is dedicated to providing an energy storage system based on a retired battery pack, and an embodiment of the present disclosure is described in detail below.

[0005] The energy storage system based on retired battery packs provided by the embodiments of the present disclosure includes: a plurality of battery clusters connected in parallel, each of the plurality of battery clusters includes a plurality of battery packs connected in series, or each of the plurality of battery clusters includes one or more battery packs and a first voltage converter, the first voltage converter is used to control one or more of the voltage, current and power of the one or more battery packs; and a battery management system (Battery Management System, BMS), which is electrically connected to the plurality of battery clusters and is used to control the charging and discharging of the plurality of battery clusters; wherein the BMS performs program updates through a controller area network (Controller Area Network, CAN) bus to update the original code of the battery pack to the energy storage code of the energy storage system.

[0006] As a possible implementation method, the battery BMS is also used to control the parallel connection of multiple battery clusters, including: sorting the voltages of multiple battery clusters, and using the voltage in the middle of the sort as the reference voltage for power-on control; according to the reference voltage, incorporating the battery cluster in the middle of the sort into the power harness; and then incorporating the battery cluster with the voltage closest to the power harness into the power harness until multiple battery clusters are successfully connected in parallel.

[0007] As a possible implementation, if there are a first battery cluster and a second battery cluster among the multiple battery clusters, and the voltage difference between the first battery cluster and the power harness is consistent with the voltage difference between the second battery cluster and the power harness, the BMS controls the first battery cluster and the second battery cluster to be simultaneously incorporated into the power harness.

[0008] As a possible implementation method, if there are a third battery cluster and a fourth battery cluster among the multiple battery clusters, the voltage of the third battery cluster is less than the voltage of the fourth battery cluster, and the absolute value of the voltage difference between the third battery cluster and the power harness is the same as the absolute value of the voltage difference between the fourth battery cluster and the power harness, the BMS first controls the third battery cluster to be integrated into the power harness, and then controls the fourth battery cluster to be integrated into the power harness.

[0009] As a possible implementation, each battery pack in a plurality of battery packs connected in series includes a pre-charging resistor, wherein during a power-on process of each battery cluster, one or more of the plurality of pre-charging resistors included in each battery cluster are used for pre-charging of each battery cluster.

[0010] As a possible implementation, during one power-on process of each battery cluster, the BMS is used to control the closing of multiple switches; and during multiple power-on processes of each battery cluster, the closing order of the multiple switches is changed; the multiple battery packs connected in series include a first battery pack and a second battery pack, and the multiple switches include: a first switch, a first end of the first switch is connected to the positive electrode of the first battery pack, and a second end of the first switch is connected to the pre-charging resistor of the first battery pack; a second switch, a first end of the second switch is connected to the negative electrode of the battery module of the first battery pack, and a second end of the second switch is connected to the negative electrode of the first battery pack; a third switch, a first end of the third switch is connected to the positive electrode of the second battery pack, and a second end of the third switch is connected to the positive electrode of the battery module of the second battery pack; and a fourth switch, a first end of the fourth switch is connected to the negative electrode of the battery module of the second battery pack, and a second end of the fourth switch is connected to the negative electrode of the second battery pack.

[0011] As a possible implementation method, when each battery cluster reaches the pre-charge voltage, the BMS controls the closing of the fifth switch and then disconnects the first switch; wherein the first end of the fifth switch is connected to the positive electrode of the first battery pack, and the second end of the fifth switch is connected to the positive electrode of the battery module of the first battery pack.

[0012] As a possible implementation method, during one power-off process of each battery cluster, the BMS is used to control the disconnection of the second switch, the third switch, the fourth switch and the fifth switch, and during multiple power-off processes of each battery cluster, the disconnection order between the second switch, the third switch, the fourth switch and the fifth switch is changed.

[0013] As a possible implementation, the BMS includes multiple battery pack management units, each of which is electrically connected to a battery pack; the multiple battery pack management units associated with each battery cluster include a master battery pack management unit and a slave battery pack management unit; wherein the energy storage codes of the master battery pack management unit and the slave battery pack management unit are different; and / or the master battery pack management unit communicates with the slave battery pack management unit via a CAN bus; and / or the master battery pack management unit is used to control all battery packs in each battery cluster for charging and discharging and / or communicate with other battery pack management units.

[0014] As a possible implementation, each battery cluster includes a plurality of battery packs connected in series, and the power end of each battery cluster includes a second voltage converter, which is used to control one or more of the voltage, current and power of each battery cluster.

[0015] The disclosed embodiment is based on the whole pack utilization of retired battery packs, directly connecting multiple retired battery packs in series as a battery cluster to achieve the secondary application of retired battery packs, thereby reducing the complexity of the secondary use of battery packs, and also avoiding the technical limitations of the battery pack disassembly process. In addition, the battery pack in the disclosed embodiment is based on the CAN bus for efficient program update. Since the CAN bus is an original component in the battery pack, the CAN-based code update does not need to disassemble the battery pack, and the implementation is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Shown is a schematic diagram of the structure of the energy storage system provided in an embodiment of the present disclosure.

[0017] Figure 2 Shown is a schematic structural diagram of a battery cluster provided in one embodiment of the present disclosure.

[0018] Figure 3 FIG. 1 is a schematic structural diagram of a battery cluster provided by another embodiment of the present disclosure.

[0019] Figure 4 FIG. 4 is a schematic structural diagram of a battery cluster provided in yet another embodiment of the present disclosure.

[0020] Figure 5 FIG. 4 is a schematic structural diagram of a battery cluster provided in yet another embodiment of the present disclosure.

[0021] Figure 6 Shown is a battery pack screening flow chart provided in an embodiment of the present disclosure.

[0022] Figure 7 Shown is a schematic diagram of the structure of a battery pack provided in an embodiment of the present disclosure.

[0023] Figure 8FIG. 4 is a schematic structural diagram of a battery cluster provided in yet another embodiment of the present disclosure.

[0024] Fig. 9 FIG. 1 is a schematic structural diagram of a battery cluster provided by another embodiment of the present disclosure.

[0025] Fig.10 Shown is a schematic structural diagram of an energy storage system provided in one embodiment of the present disclosure. DETAILED DESCRIPTION

[0026] 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, rather than all of the embodiments.

[0027] The power battery pack is an integrated battery system that can provide power for vehicles. In new energy vehicles, the power battery pack can provide power for electric vehicles, hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV) and battery electric vehicles (BEV), and has the characteristics of high energy density, fast charging, and long driving range. In electric ships, the power battery pack can provide power for electric ships, reduce their dependence on fossil fuels, and reduce emissions. It is characterized by large capacity, durability, and suitability for long-term navigation. In spacecraft, the power battery pack can provide power for satellites, spacecraft, drones, etc. It is characterized by high durability, lightweight, and adaptability to extreme environments (such as high temperature, low temperature, radiation, etc.).

[0028] As the usage time and the number of charge and discharge cycles increase, the performance and capacity of the power battery pack will gradually decline. When the power battery pack can no longer provide the required power for the vehicle, it is called a retired battery pack. Generally, a retired battery pack refers to a power battery pack whose battery capacity has decayed to less than 80% of the initial capacity, or a power battery pack that cannot meet the performance requirements of the vehicle.

[0029] Although retired battery packs can no longer provide the required power for vehicles, they still have certain potential for use. Simply discarding retired battery packs will not only cause environmental pollution, but also waste the power resources in them. According to the definition of retired battery packs mentioned above, retired battery packs still retain a certain capacity and therefore have a corresponding cycle life, so they can be used for a second time, especially in a cascade manner.

[0030] Through reasonable application strategies, retired battery packs can continue to play their value in many fields, such as energy storage systems. Retired battery packs can be used in home energy storage systems to help home users store and use electricity during peak electricity demand periods and reduce dependence on the power grid. In addition, retired battery packs can also be used in grid energy storage systems or commercial energy storage systems to provide power storage and peak load regulation functions, balance grid loads, and improve the stability and efficiency of power systems. In addition, retired battery packs can also be used in uninterruptible power supply (USP) systems and backup power supplies, industrial energy storage applications, and smart grids to reduce the demand for new battery materials and reduce production costs, while extending the service life of battery packs and reducing the impact of discarded batteries on the environment.

[0031] The power battery pack may include multiple battery modules and a battery management unit (BMU). Each battery module may contain multiple cells. Multiple battery modules can provide the required voltage and capacity for the power battery pack by connecting in series or in parallel. The BMU is responsible for performing battery monitoring and control tasks, such as balancing, protection actions, etc.

[0032] When reusing retired battery packs, the method usually adopted is to disassemble them, that is, to separate the multiple battery modules and BMU in the retired battery pack, and then test, screen and match the separated battery modules (or cells) separately to reassemble the battery modules (or cells) with similar battery status parameters (such as capacity, voltage, etc.) into a battery pack. In addition, it is necessary to redesign, develop, manufacture and match the BMU and related circuits in the battery pack.

[0033] However, the disassembly and reassembly of power battery packs is not only a tedious and high-risk task, but also involves a large number of complex technical challenges and safety issues.

[0034] The first thing you need to face when disassembling a power battery pack is its high level of complexity. Since a battery pack is usually made up of dozens or even hundreds of battery modules (and a larger number of battery cells) that are tightly packed together, and each battery module has complex wiring connections (there are also connectors between the battery cells and the battery modules they are in), the disassembly work becomes extremely meticulous and time-consuming. Disassembly personnel need to disconnect these wiring and / or connectors one by one, while also ensuring that the battery modules and / or battery cells are not damaged, so as not to affect the subsequent secondary use of the battery pack.

[0035] In addition to the tediousness, the difficulty of disassembling the power battery pack cannot be ignored. The design of the battery pack is often very compact, so the space left for disassembly operations is limited. At the same time, since the connection between the battery modules may be designed with high-voltage circuits, the disassembly personnel must have professional electrical knowledge to ensure personal safety during the operation. In addition, special tools and equipment such as insulating gloves, high-voltage safety switches and heat guns are also required to assist in completing the disassembly task.

[0036] When disassembling power battery packs, technical limitations may also be encountered. First, the design of some battery packs may not support non-destructive disassembly, which means that the battery module and / or battery cell may inevitably be damaged during the disassembly process. Secondly, even if the battery pack supports disassembly, due to technical barriers or patent protection, the disassembler may lack the necessary guidance or tools, resulting in inefficient disassembly or even failure. Finally, during the disassembly process, it is also necessary to consider how to safely handle possible hazardous substances, such as leaked electrolyte, to prevent pollution to the environment.

[0037] Before disassembling the power battery pack, some measures must be taken to ensure the safety and effectiveness of the disassembly operation. Relevant measures may include: first, the battery pack needs to be fully discharged to reduce the risk of short circuit or fire, such as by gradually reducing the voltage or using special discharge equipment; second, the battery pack is isolated from other flammable and explosive items to ensure a risk-free disassembly environment. In addition, the battery pack should be properly packaged, such as using materials with good insulation and impact resistance, to prevent physical damage or further damage during subsequent disassembly, ensuring safe operation and the integrity of the battery pack. These safety measures further increase the complexity of disassembly and require additional time and resources.

[0038] In addition, the difficulty of reassembling the power battery pack should not be underestimated. During the disassembly process, the battery module (or battery cell) may have undergone slight deformation or damage, which will affect the accuracy and stability of the reassembly. In addition, due to the complexity of the internal structure of the battery pack, it is necessary to ensure the accuracy of the connector and line design and installation during reassembly, otherwise the battery pack may not work properly or there may be safety hazards. Therefore, the reassembly of the battery pack requires extremely high professional skills and experience of the operator.

[0039] During the reassembly of the battery pack, technical limitations and challenges may also be encountered. First, if key components or connectors are damaged during the disassembly process, these parts may not be perfectly repaired or replaced, resulting in reassembly failure. Second, even if all parts are intact, slight errors or improper operation during the assembly process may cause the battery pack to degrade in performance or pose safety hazards. Finally, rigorous testing and verification work is required after reassembly to ensure that the battery pack can work properly and meet performance requirements. These tests and verification work also require professional equipment and technical support, which increases the difficulty and cost of reassembly.

[0040] During the battery pack reassembly process, the battery pack structure needs to be redesigned and the BMS needs to be matched to ensure that the reassembled battery pack can be used normally. Among them, the redesign of the battery pack structure needs to comprehensively consider multiple factors such as heat dissipation, weight distribution, mechanical stability, and carry out detailed layout design to ensure the performance and safety of the battery pack. This process requires not only delicate operations and high-precision measurement equipment, but also a large amount of simulation and analog calculations, which increases the difficulty and complexity of the design.

[0041] In addition, re-matching the BMS is also a difficult task. The BMS needs to be able to accurately identify and monitor the new battery pack structure, including the voltage, temperature and other parameters of each battery module and / or battery cell. Therefore, the disassembled battery modules and / or batteries need to undergo detailed parameter testing, and then the BMS is reconfigured and calibrated to ensure that it can work properly and provide accurate monitoring data and control instructions. This process requires adjustments to the BMS internal algorithms and parameters, as well as a lot of testing and verification, which increases the difficulty and complexity of the reassembly process.

[0042] In summary, when reusing retired battery packs, the disassembly and reassembly process is complicated, the workload of disassembly and reassembly is large, and the BMS needs to be re-matched, which increases the cost of re-utilization.

[0043] In response to the above problems, the applicant found that the voltage platforms commonly used in the battery packs of electric vehicles (the voltage platform refers to the voltage standard or range adopted by the battery system or energy storage system during design and operation) include 400V voltage platform and 800V voltage platform. In practical applications, the 400V voltage platform can refer to the voltage range of 350V to 450V, and the 800V voltage platform can refer to the voltage range of 750V to 850V, so as to ensure that the system can adapt to voltage fluctuations in practical applications and ensure safety and reliability. Among them, the 400V voltage platform is a more common voltage standard on the market and is widely used in various types of electric vehicles, including sedans, sport utility vehicles (SUVs) and light commercial vehicles. The 800V voltage platform is widely used in high-performance electric vehicles and high-end models, and it is also the development trend of vehicle voltage standards in recent years.

[0044] In addition, some existing high-voltage energy storage systems generally use 1000V or 1500V voltage platforms (i.e., voltage range of 950V to 1050V or voltage range of 1450V to 1550V), with 1500V voltage platforms being the most common. For example, grid-level energy storage systems usually use 1500V voltage platforms to meet large-capacity, high-power energy storage needs, while also improving system efficiency and safety; large-scale commercial energy storage systems may also use high-voltage platforms to improve energy storage efficiency and system reliability.

[0045] According to the above findings, and based on the high complexity and technical limitations of the existing retired battery packs in the process of realizing secondary use through disassembly and reassembly, the applicant proposed that it is not necessary to disassemble the retired battery packs, and directly use multiple electric vehicle power battery packs in series to form a battery cluster that meets the voltage standards required by the high-voltage energy storage system, thereby reducing the complexity of the secondary use of retired battery packs and avoiding technical limitations. For example, after four battery packs with a 400V voltage platform are connected in series, a battery cluster with a voltage range of 1400V to 1800V can be obtained, which can meet the voltage standards required by the energy storage system of the 1500V voltage platform; for example, after two battery packs with a 800V voltage platform are connected in series, a battery cluster with a voltage range of 1500V to 1700V can be obtained, which can meet most battery clusters with 1500V voltage standards.

[0046] Through further research on the above viewpoints, the present disclosure proposes the utilization of retired battery packs as a whole pack, directly connecting multiple retired battery packs in series as a battery cluster to achieve secondary use, thereby simplifying the complexity of the secondary use of power battery packs and avoiding technical limitations.

[0047] Further, Figure 1FIG. 1 shows a schematic diagram of the structure of an energy storage system based on a retired battery pack provided by an embodiment of the present disclosure. Figure 1 As shown, the energy storage system 100 may include multiple battery clusters 120 and a BMS 140 connected in parallel. The multiple battery clusters and the BMS connected in parallel are described in detail below. For convenience, the retired battery pack is referred to as a battery pack in the following text.

[0048] In the energy storage system, multiple battery clusters connected in parallel are responsible for storing and outputting electrical energy. The disclosed embodiments do not limit the structure of the battery cluster. In some embodiments, the battery cluster may include multiple battery packs connected in series to form a higher voltage battery cluster. In other embodiments, a high voltage battery cluster may also be formed by connecting one or more battery packs to a first voltage converter.

[0049] Figure 2 A possible structure of a battery cluster is shown in FIG. Figure 2 As shown, a battery cluster can be formed by connecting multiple battery packs in series. The series connection between multiple battery packs can realize the transmission of electric energy between the battery packs through connecting wires, thereby ensuring the effective transmission of voltage and current between the multiple battery packs. The embodiment of the present disclosure is not limited to the type of connecting wires. As a possible implementation method, a power harness (or power connecting wire) capable of withstanding high voltage and high current output can be used to connect multiple battery packs to transmit electric energy between multiple battery packs. The power harness includes a positive wire that can be used to connect the positive electrode of the battery pack and a negative wire that can be used to connect the negative electrode of the battery pack. In addition, the power harness has the characteristics of good electrical isolation and beautiful wiring.

[0050] For example, Figure 2 As shown, the negative wire of power harness 1 is connected to the negative pole of battery pack 1, the positive pole of power harness 1 is connected to the positive pole of battery pack 2, the negative wire of power harness 2 is connected to the negative pole of battery pack 2, the positive pole of power harness 2 is connected to the positive pole of battery pack 3, and so on, until battery pack n is connected to the battery cluster through the power harness.

[0051] In addition, if Figure 2 As shown, the positive electrode of battery pack 1 is the positive electrode of the battery cluster, and the negative electrode of battery pack n is the negative electrode of the battery cluster. It should be understood that Figure 2 The series connection sequence of the multiple battery packs shown is only exemplary and is not limited in the embodiments of the present disclosure. It should be understood that the positive and negative connections of the battery clusters are also different in different series connection sequences.

[0052] like Figure 2As shown, between multiple battery packs, in addition to the power transmission connection based on the connecting wire (such as the power harness), the communication connection of the CAN bus can also be included. The CAN bus can be used to transmit key parameters such as the voltage, current, temperature, and state of health (SOH) of each battery pack. These parameters are the basis for the energy storage system to monitor and manage the battery pack. In other words, the instructions received by the battery cluster (such as charge and discharge control instructions, etc.) are sent to multiple battery packs through the CAN bus to ensure that all battery packs work together to maintain overall performance and safety.

[0053] The above content describes in detail a battery cluster formed by a plurality of battery packs connected in series. In the embodiment of the present disclosure, the battery cluster may also be composed of a battery pack and a first voltage converter.

[0054] Figure 3 A schematic diagram of a battery cluster consisting of a battery pack and a first voltage converter is shown. It should be understood that Figure 3 The number of battery packs is only exemplary. In the battery cluster composed of the battery pack and the first voltage converter in the embodiment of the present disclosure, the battery pack may be one or more. When there are multiple battery packs, the connection method between the multiple battery packs may be the same as the connection method between the multiple battery packs mentioned above, that is, multiple battery packs are connected in series; or they may be connected in a combination of series and parallel, which is not limited in the embodiment of the present disclosure.

[0055] As a connection method, such as Figure 3 As shown, the positive input terminal of the first voltage converter 320 is connected to the positive terminal of the battery pack 4, and the negative input terminal is connected to the negative terminal of the battery pack 6; the positive output terminal of the first voltage converter 320 is connected to the positive terminal of the battery cluster, and the negative output terminal is connected to the negative terminal of the battery cluster.

[0056] The first voltage converter can be used to control one or more of the voltage, current and power of each battery cluster, that is, to control the input and output parameters of (one or more) battery packs in the battery cluster, so as to convert the input and output parameters of (one or more) battery packs in the battery cluster into the parameters required by the energy storage system, thereby ensuring the stability and reliability of the energy storage system.

[0057] In some embodiments, the first voltage converter can adjust the output voltage of the battery pack. For example, when the output voltage of the battery pack is lower than the voltage required by the energy storage system, the first voltage converter can achieve voltage boost, that is, increase the output voltage of the battery pack to the voltage required by the energy storage system; when the output voltage of the battery pack is higher than the voltage required by the energy storage system, the first voltage converter can achieve voltage reduction, that is, reduce the output voltage of the battery pack to the voltage required by the energy storage system.

[0058] In other embodiments, the first voltage converter can balance the battery state of charge (SOC) of the battery pack by controlling the output current of the battery cluster to extend the life of the battery pack. As a method, the first voltage converter can distribute current according to the battery capacity ratio of each battery cluster. For example, when the battery capacity of the current battery cluster is significantly lower than that of other battery clusters, the current battery cluster can output a corresponding current based on the current distribution result of the first voltage converter, that is, output a smaller current; similarly, when the battery capacity of the current battery cluster is significantly higher than that of other battery clusters, the current battery cluster outputs a larger current.

[0059] In some other embodiments, the first voltage converter can implement the control of the input and output power of the battery cluster. As a method, one or more of the voltage and current of the battery cluster can be adjusted simultaneously.

[0060] In order to prevent the battery pack from being damaged, in the embodiment of the present disclosure, for a battery cluster that reaches the charge and discharge protection condition (such as the overcharge or over-discharge threshold) in advance, the first voltage converter can shut down the current output in advance to prevent the battery pack from being damaged by overcharge or over-discharge, thereby extending the service life of the battery pack.

[0061] It should be understood that the above functional description of the first voltage converter is merely exemplary. In the embodiments of the present disclosure, the first voltage converter may also include other functions, such as short-circuit protection and thermal shutdown, etc., which are not limited in the embodiments of the present disclosure.

[0062] The embodiment of the present disclosure does not limit the type of the first voltage converter. In some embodiments, a direct current to direct current (DC-DC) converter can be used. The DC-DC converter can convert a direct current voltage into another direct current voltage to achieve output voltage regulation, output current control, input and output power control, etc., and provide the required output voltage, current, power and other parameters.

[0063] When multiple battery packs are involved, the first voltage converter can be connected to the power terminals of multiple series and / or parallel battery packs to adjust and stabilize the input and output parameters of the battery cluster. In this case, usually only one first voltage converter is required, and the design is relatively simple.

[0064] It should be understood that the first voltage converter mentioned here only needs one, which means that for the purpose of simplifying the circuit, for example, a first voltage converter used to adjust the output voltage, a single one can meet normal needs. This does not mean that there is a limit on the number of first voltage converters (for example, multiple first voltage converters can also be set to improve fault tolerance), nor does it limit the total number of voltage converters in the circuit. For example, when it is necessary to balance the voltage between multiple series and / or parallel battery packs, additional voltage converters can be connected inside these battery packs to assist in achieving voltage balance. In addition, if the input voltage needs to be adjusted, a voltage converter can be connected to the input end of the first battery pack, that is, the input end of the battery cluster, to prevent circuit damage caused by overvoltage or undervoltage.

[0065] Based on the different structures of the battery clusters mentioned above, namely, the structure of the battery cluster formed by directly connecting multiple battery packs in series and the structure of the battery cluster composed of (one or more) battery packs and the first voltage converter, in the embodiments of the present disclosure, the multiple battery clusters connected in parallel included in the energy storage system also have different structures. In some embodiments, the structure of each battery cluster in the multiple battery clusters connected in parallel is as follows: Figure 2 As shown, that is to say, each battery cluster is composed of multiple battery packs connected in series. This method of directly connecting multiple battery packs in series is simpler to implement.

[0066] In some other embodiments, each battery cluster in the plurality of battery clusters connected in parallel is composed of a battery pack and a first voltage converter. Figure 4 As shown, each battery pack is connected to a first voltage converter to form a battery cluster, and then multiple battery clusters are connected in parallel. This implementation method reduces the selection requirements for battery packs (the selection criteria will be described in detail later), allowing more retired battery packs to be put into secondary use.

[0067] In some other embodiments, among the multiple battery clusters connected in parallel, some battery clusters are battery clusters formed by connecting multiple battery packs in series, and others are battery clusters formed by combining a battery pack with a first voltage converter. Figure 5 As shown, in the structure formed by four battery clusters connected in parallel, battery clusters 9 and 10 are formed by multiple battery packs connected in series, and battery packs 11 and 12 are respectively connected to first voltage converters 11 and 12 to form battery clusters. This implementation method simplifies the implementation of battery clusters to a certain extent, and also reduces the threshold for the secondary use of retired battery packs. It should be understood that Figure 5 This is merely exemplary and does not constitute a limitation on the ratio of the two specific battery cluster structures or the number of battery packs included.

[0068] The selection of the above three different structures of multiple battery clusters connected in parallel can be based on comprehensive considerations such as the actual number of battery packs, battery parameters, and requirements of the energy storage system, and is not limited in the embodiments of the present disclosure.

[0069] The above details the multiple battery clusters connected in parallel in the energy storage system. The charging and discharging of the battery clusters directly affects the performance, life, safety and overall efficiency of the energy storage system. Therefore, the BMS used to control the charging and discharging of multiple battery clusters is introduced below. Since BMS includes multiple levels, for ease of understanding, the management of each level included in BMS is introduced from low level to high level.

[0070] First of all, the smallest management unit in the BMS is the BMU, which is responsible for managing and monitoring the battery modules in the battery cluster to ensure that the battery cells in each module operate within a safe range. Specifically, the BMU can monitor the voltage and temperature of each battery cell in real time to ensure its safe operation; the BMU can also monitor the internal resistance of the battery cell in real time to diagnose the health status of the battery; the BMU can also ensure that the voltages of multiple battery cells are consistent through the balancing circuit to avoid excessive charging and discharging of certain cells; the BMU can also communicate with other units through the CAN bus to transmit battery cell status information. In other words, the BMU can achieve high-density monitoring of the energy storage system, and the BMU can work independently and flexibly connect, providing the most basic monitoring and management for the entire energy storage system.

[0071] Based on the integration of battery module information provided by multiple BMUs, the Battery Control Unit (BCU) can implement internal management of the battery pack. The BCU manages the high-voltage box and battery modules in the battery pack by collecting data and battery algorithms from all BMUs in the battery pack (for specific internal management, please refer to the relevant description in the battery pack structure later). In addition to the internal management of the battery pack, some BCUs can also implement management between multiple battery packs. The management between battery packs involved in the BCU includes the management between battery packs in the same battery cluster. Specifically, it can collect data from BCUs in other battery packs in the battery cluster, and take relevant measures in a timely manner to ensure energy balance and safe operation between the battery packs; in addition, the BCU can also communicate with other battery packs through the CAN bus, thereby transmitting battery pack status information and control instructions.

[0072] According to the management of BMU and BCU, the Battery Administration Unit (BAU) can control multiple battery clusters (i.e., battery arrays) in parallel as a whole to improve the safety and efficiency of the energy storage system. In other words, BAU can manage the clustering of battery cells in the entire battery array to realize the charging and discharging of the energy storage system. The embodiments of the present disclosure do not limit the specific configuration of BAU. In some embodiments, BAU can be equipped with a high-performance processor and data storage device to realize complex data analysis and processing. In other embodiments, BAU can support multi-node CAN communication to ensure the coordinated operation of multiple battery clusters.

[0073] In addition, the energy storage system has strict requirements for the management of the battery pack, including but not limited to precise charge and discharge control, real-time monitoring, protection mechanism, etc. The original code in the battery pack may not meet these high-standard management requirements. Therefore, it is necessary to update the original code in the battery pack to the energy storage code of the energy storage system. In the embodiment of the present disclosure, this work is completed by the BMS. Specifically, the BMS updates the original code of the battery pack of the energy storage system through the BCU.

[0074] The embodiment of the present disclosure does not limit the update method of the battery pack code. In some embodiments, it can be implemented by firmware upgrade, which is more efficient and commonly used. As an implementation method, the firmware can be upgraded through a specific communication interface. The embodiment of the present disclosure does not limit the choice of the communication interface. As a method, it can be implemented through the CAN bus, because the CAN bus is an original component in the battery pack, and the CAN-based code update can be implemented without disassembling the battery pack. It should be understood that when upgrading the battery pack code through firmware, it is necessary to ensure that the updated code is compatible with the existing hardware and can run stably in actual applications.

[0075] Based on the above-mentioned utilization of the whole package of retired battery packs, multiple retired battery packs are directly connected in series as a battery cluster to realize the secondary use of retired battery packs, thereby reducing the complexity of the secondary use of battery packs and avoiding technical limitations in the disassembly process of battery packs. In addition, through the collaborative work of different levels of management including BMU, BCU and BAU, and the efficient program update of the battery pack based on the CAN bus, the BMS can realize multi-level monitoring and management of battery modules, battery packs, and battery clusters to ensure the safety, life and overall performance of the energy storage system.

[0076] From the above content, it can be seen that whether it is a battery cluster composed of multiple battery packs directly connected in series, or a battery cluster composed of a battery pack and a first voltage converter, it involves the selection and / or series connection of battery packs. For the consideration of the stability and safety of the energy storage system, such as Figure 6 As shown, when multiple battery packs are connected in series, as in step S610, the relevant parameters of each battery pack need to be collected through the charging and discharging equipment. The charging and discharging equipment can accurately measure various parameters of the battery pack, including voltage, current, capacity, internal resistance, cycle life, etc., to help users evaluate battery performance more comprehensively.

[0077] The present disclosure does not limit the type of charging and discharging equipment, such as a battery tester, a battery analyzer, a comprehensive battery testing system, etc.

[0078] The embodiments of the present disclosure do not limit the methods that can be used for charging and discharging equipment. As one method, the charging and discharging equipment can be used to directly measure the parameters of the battery pack. This method is relatively simple and direct, and has high real-time performance. As another method, the built-in data recorder of the charging and discharging equipment can be used to record the parameters of the battery pack in real time and store them in the memory of the device. This method is convenient for users to retrospectively analyze the historical performance of the battery. As another method, the charging and discharging process of the battery pack can be automatically controlled by the built-in controller of the charging and discharging equipment or an external control device (such as computer software), and data can be collected in real time. In addition, in order to ensure the real-time, accuracy and comprehensiveness of the battery pack data, the parameters of the battery pack can also be collected in combination with the above multiple methods.

[0079] After the relevant parameters of each battery pack are collected, as in step S620, suitable battery packs are screened out based on the screening criteria.

[0080] In the disclosed embodiment, the screening criteria for the battery pack are intended to prevent the output of the entire battery cluster from being affected by excessive differences in the relevant parameters of the battery pack, and even causing safety problems. Therefore, battery packs with relatively close relevant parameters can be screened. As one way, battery packs with relatively close capacities are selected to ensure that the voltage distribution of multiple battery packs is more balanced and to prevent the risk of overcharging or over-discharging of a battery pack. For example, battery packs with a capacity of about 80% (or in the range of 78% to 82%) are selected for series connection. As another way, battery packs with relatively close voltages are selected to ensure that the current distribution of multiple battery packs is more balanced and to prevent damage to a battery pack due to overcurrent. For example, battery packs with a voltage of about 400V (or in the range of 380V to 420V) are selected for series connection. As another way, battery packs with relatively close voltages and capacities are selected to make the charging and discharging characteristics of multiple battery packs more balanced and to extend the service life of the entire battery cluster. For example, a battery pack with a capacity of about 80% (or in the range of 78% to 82%) and a voltage of about 400V (or in the range of 380V to 420V) is connected in series. It should be understood that the above specific voltage or capacity values ​​are merely exemplary and are not specific limitations thereto.

[0081] like Figure 6 In step S630, the selected battery packs are connected in series to form a battery cluster. As a possible method, the selected multiple battery packs are connected through a power harness to form a battery cluster. In addition, multiple battery packs are connected based on CAN to facilitate communication between battery packs.

[0082] The energy storage system proposed in the embodiment of the present disclosure is provided with electric energy by multiple battery clusters connected in parallel, wherein the multiple battery clusters connected in parallel include at least one battery pack. Figure 7 Briefly introduce the structure of the battery pack.

[0083] like Figure 7 As shown, the battery pack 700 includes a BCU 720 , a high voltage box 740 and a plurality of battery modules 760 .

[0084] Among them, BCU can be used to collect battery parameters such as voltage, current, internal resistance, etc. of the battery module, and based on the collected battery parameters, evaluate the battery's SOH, SOC and power state (State of Power, SOP), and then implement overcharge protection, over-discharge protection, overcurrent protection, short-circuit protection, etc. to ensure the safe operation of the battery pack. In addition, the battery pack can also communicate with other battery packs or components based on the BCU.

[0085] In the process of BCU managing the battery pack, the high-voltage box is an indispensable component. The high-voltage box can be used to accommodate and protect the high-voltage circuit in the battery pack and provide protection such as overvoltage, undervoltage, overcurrent, short circuit, etc. to ensure safety. In the embodiment of the present disclosure, the high-voltage box can include integrated multiple protection devices to detect and respond to abnormal protection circuits, such as relays ( Figure 7 K1, K2 and K3 in), fuse ( Figure 7 F1 in) and pre-charge resistor (such as Figure 7 In addition, the high-voltage box may also include other conventional devices, such as built-in sensors, high-voltage distribution boards, cooling systems, and highly insulating and waterproof housings.

[0086] During operation, the high-voltage box 740 receives high-voltage power from the multiple battery modules 760, and based on the instructions of the BCU 720, controls the closing and opening of one or more of the relays K1, K2, and K3 to manage and distribute power; based on the built-in sensors ( Figure 7 (not shown), the high-voltage box 740 monitors parameters such as voltage and current in real time, and transmits these parameters to the BCU 720; when abnormal conditions such as overvoltage, undervoltage, overcurrent, short circuit, etc. are detected, the high-voltage box 740 triggers a protection mechanism to cut off the circuit or limit the current to ensure the safety of the battery pack.

[0087] In order to withstand high voltage and large current, in the embodiment of the present disclosure, the connection between the high-voltage box and the battery module can use a power harness or other connecting wires that can withstand high voltage and large current to transmit high-voltage electrical energy; in addition, the high-voltage box and the BCU can communicate using CAN lines or other control signal lines to transmit control instructions and status information.

[0088] Continue to combine Figure 7 In the battery 700 , a plurality of battery modules 760 provide energy storage and voltage output for the battery pack 700 , and are also managed by the BCU 720 and the high-voltage box 740 .

[0089] The embodiment of the present disclosure does not limit the connection mode of multiple battery modules. In the embodiment of the present disclosure, each battery module can be connected in series, in parallel, or in a combination of series and parallel. Figure 7 It is shown that multiple battery modules are connected in series. In addition, each battery module is composed of multiple battery cells connected in series, in parallel, or in a combination of series and parallel. Multiple battery cells can increase voltage by connecting in series, or increase capacity by connecting in parallel.

[0090] As mentioned above, multiple battery clusters are connected in parallel (i.e., clustered) to form a battery array, which is controlled by the BAU. The disclosed embodiment does not limit the connection method when multiple battery clusters are connected in parallel to transmit electric energy to form a battery array. As a method, a power harness can be used to transmit electric energy.

[0091] In the embodiment of the present disclosure, for the sake of line safety, the voltage difference generated by multiple battery clusters during the clustering process can be controlled within a small range. As a possible implementation method, multiple battery clusters to be incorporated into the battery array are first sorted according to voltage size, and the voltage at the middle position is used as the reference voltage for power-on control.

[0092] The embodiments of the present disclosure do not limit the specific sorting method. For example, the multiple battery clusters can be sorted from large to small voltage, or from small to large voltage.

[0093] In the disclosed embodiment, when the number of battery clusters is an odd number, the middle position of the plurality of battery clusters after sorting is the only determined position. Specifically, if the number of battery clusters is (2n-1, where n is greater than 1), the battery cluster at the middle position is the nth battery cluster. For example, when there are 9 battery clusters to be incorporated into the battery array after sorting, the middle position refers to the position of the 5th battery cluster.

[0094] When the number of battery clusters is an even number, the middle position of the multiple sorted battery clusters numerically refers to the position of the two middle battery clusters. Specifically, if the number of battery clusters is 2n, then the battery clusters in the middle position are the nth and (n+1)th battery clusters. At this time, the position of the nth battery cluster can be regarded as the middle position, or the position of the (n+1)th battery cluster can be regarded as the middle position. The embodiments of the present disclosure do not limit this. In some embodiments, in order to further reduce the voltage difference, the average voltage of multiple battery clusters can be calculated, and then the battery cluster closest to the two average voltages in the middle two battery clusters is used as the battery cluster in the middle position. In particular, when the absolute value of the voltage difference between the two middle battery clusters and the average voltage is consistent, the battery cluster with a slightly smaller voltage in the two battery clusters can be selected as the battery cluster in the middle position.

[0095] The determined battery cluster voltage at the middle position is used as the reference voltage, and the battery cluster is incorporated into the connection line (such as the power harness) of the battery array. At this time, the voltage on the connection line (that is, the power harness) of the battery array is the voltage of the battery cluster at the middle position.

[0096] Next, the battery cluster with the closest voltage to the connection line among the sorted battery clusters is merged into the connection line. The closest battery cluster refers to the battery cluster with the smallest voltage difference to the voltage on the connection line.

[0097] Then, the above steps are repeated, that is, the battery cluster with the voltage closest to the connection line is continuously selected from the sorted battery clusters and connected to the connection line until all battery clusters are successfully connected in parallel.

[0098] In the process of combining the above-mentioned multiple battery clusters, if the voltage difference between the first battery cluster and the battery array connecting line is consistent with the voltage difference between the second battery cluster and the battery array connecting line, the first battery cluster and the second battery cluster can be combined into the battery array at the same time, thereby improving the efficiency of combining the batteries while ensuring safety.

[0099] In the embodiment of the present disclosure, there is no limitation on the relative voltages of the first battery cluster and the second battery cluster to the battery array connection line. For example, the voltage of the first battery cluster is equal to the voltage of the second battery cluster, and the voltage of the first battery cluster (or the voltage of the second battery cluster) is greater than the voltage of the battery array connection line; for another example, the voltage of the first battery cluster is equal to the voltage of the second battery cluster, and the voltage of the first battery cluster (or the voltage of the second battery cluster) is less than the voltage of the battery array connection line.

[0100] In the process of combining the above-mentioned multiple battery clusters, if the voltage of the third battery cluster is less than the voltage of the fourth battery cluster, and the absolute value of the voltage difference between the third battery cluster and the battery array connecting line voltage is the same as the absolute value of the voltage difference between the fourth battery cluster and the battery array connecting line voltage, the third battery cluster can be combined first, and then the fourth battery cluster can be combined, so as to control the battery array connecting line voltage at a relatively low condition, thereby further improving safety.

[0101] For example, at a certain moment in the clustering process, the battery array connection line voltage is 1500V. At this time, among the multiple battery clusters in order, the third battery cluster is 1488V and the fourth battery cluster is 1512V. At this moment, the third and fourth battery clusters are the battery clusters closest to the battery array connection line voltage among the multiple battery clusters. At this time, the third battery cluster can be merged first, and then the fourth battery cluster.

[0102] As mentioned above, the management function of BAU includes monitoring and managing the operating status of the battery cluster. One of its main responsibilities is to calculate and maintain the key data of the battery cluster, including the number of battery clusters that are finally successfully connected, the available capacity and the available power. These calculations are achieved by monitoring the status and performance of the battery cluster in real time.

[0103] In the disclosed embodiment, after the BAU calculates the number of battery clusters that are finally successfully clustered, the available capacity and the available power, this information can be reported to the Energy Management System (EMS). As the control center of the entire energy storage system, EMS can use this information to optimize and manage distributed energy resources, energy storage systems, and interactions with the power grid. As one way, the EMS can make decisions on energy scheduling and management based on the current state, available capacity, and power of the battery cluster. As another way, the EMS can also limit the power output of the power harness (for example, dynamically adjust the maximum power output of the power harness) based on the current state, available capacity, and power of the battery cluster to prevent overload or over-discharge and ensure the safe operation of the energy storage system.

[0104] It should be understood that in the embodiments of the present disclosure, BMS and EMS are integrated and collaborated with each other to make the energy storage system work more efficiently. Among them, BMS mainly focuses on the precise management and protection of batteries to ensure the safety and efficient operation of batteries; while EMS focuses on the energy scheduling and optimization of the entire energy storage system to ensure the full utilization of energy and the stable operation of the power grid.

[0105] It should be understood that in the above cluster connection process, if a battery cluster fails, in order to reduce the impact on the entire cluster connection process, the battery cluster connection can be immediately interrupted and other battery clusters can be connected according to the above cluster connection process.

[0106] The energy storage system in the embodiment of the present disclosure, which is composed of multiple battery clusters and a complete battery array, can store electrical energy and release electrical energy when needed. In other words, the working process of the energy storage system includes a charging process, i.e., the process in which the energy storage system stores electrical energy, and a discharging process, i.e., the process in which the stored electrical energy is released. Figure 8 , taking a battery cluster consisting of two battery packs connected in series as an example, the charging and discharging process of the battery cluster is introduced in detail. It should be understood that Figure 8 This is only an example and is not intended to limit the specific structure of the battery cluster.

[0107] like Figure 8 As shown, the battery cluster 800 includes a battery pack 810 and a battery pack 820, and the battery packs 810 and 820 are connected via a power harness, the positive electrode of the battery pack 810 is connected to the positive electrode of the power harness as the positive electrode of the battery cluster, the negative electrode of the battery pack 820 is connected to the negative electrode of the power harness as the negative electrode of the battery cluster, and the negative electrode of the battery pack 810 is connected to the positive electrode of the battery pack 810. At this time, the battery pack 810 is called the first battery pack, and the battery pack 820 is called the second battery pack.

[0108] It should be understood that the connection order of the battery packs in the battery cluster is merely exemplary, that is, the positive electrode of the battery pack 810 serves as the positive electrode of the battery cluster, the negative electrode of the battery pack 810 is connected to the negative electrode of the battery pack 820, and the negative electrode of the battery pack 820 serves as the negative electrode of the battery cluster is merely exemplary. In the embodiment of the present disclosure, the connection order of the battery packs in the battery cluster is not limited. As another way, the positive electrode of the battery pack 820 can serve as the positive electrode of the battery cluster, the negative electrode of the battery pack 820 is connected to the positive electrode of the battery pack 810, and the negative electrode of the battery pack 810 serves as the negative electrode of the battery cluster. In this case, the battery pack 820 is the first battery pack, and the battery pack 810 is the second battery pack.

[0109] It should be understood that the connection method between the above-mentioned battery packs, that is, the connection method between battery pack 810 and battery pack 820 is merely exemplary. In the embodiment of the present disclosure, the battery packs may also be connected via their connecting lines.

[0110] In addition, if Figure 8 As shown, the battery control unit of battery pack 810 is BCU1, and the battery control unit of battery pack 820 is BCU2, and BCU1 and BCU2 are connected to each other through a CAN line. Among them, BCU1 is the master BCU and BCU2 is the slave BCU. It should be understood that a battery cluster includes a master BCU and a slave BCU. The master BCU can be the BCU of any battery pack in the battery cluster, and the BCUs of other battery packs except the master BCU are all slave BCUs. That is to say, in Figure 8 In the battery cluster shown, BCU2 can also be the master BCU, in which case BCU1 is the slave BCU.

[0111] It should be understood that in addition to the internal management of the battery pack mentioned above, the main BCU can also implement other external management. The external management of the main BCU includes collecting BCU data from other battery packs in the battery cluster, and taking timely measures to ensure energy balance and safe operation between battery packs; controlling the charging and discharging of all battery packs in the battery cluster and / or communicating with other slave BCUs; interacting with components outside the battery cluster to avoid low communication efficiency caused by the independent operation of multiple BCUs in the battery cluster. As a way, multiple main BCUs in the same battery array can be connected to the BAU via the CAN line to achieve external communication. As an example, when the battery cluster reaches the charging (or discharging) limit, the main BCU can apply to the BAU for disconnection via the CAN line. After receiving the BAU's permission to disconnect command, this cluster (when a DC-DC converter is connected, the output power of the DC-DC converter is first controlled to be reduced to 0) disconnects all relays in sequence according to the command of the main BCU; at the same time, the BAU recalculates the power of the online battery cluster. When the online battery cluster cannot meet the power demand, the BAU applies to the upper side (for example, to the EMS) to stop working and disconnects all (when a DC-DC converter is connected, the output power of the DC-DC converter is first controlled to be reduced to 0)) battery clusters.

[0112] It should be understood that based on different functions, the codes for energy storage in the master BCU and the slave BCU are also different.

[0113] It should be understood that, as mentioned above, the master BCU and the slave BCU can be connected via a CAN line to achieve communication. Other connection methods can also be used for communication, which is not limited in the present disclosure.

[0114] In the disclosed embodiment, the BCU can also be configured to carry multiple versions of programs at the same time, so as to flexibly switch the currently running program version according to software configuration (such as remote configuration tools) or interface information input (such as high and low level signals, dip switches, etc.), thereby eliminating the traditional secondary program burning link.

[0115] It should be understood that Figure 8 The connection method between multiple BCUs in a battery cluster is also exemplary and does not constitute a limitation on the connection method.

[0116] As mentioned earlier, a variety of protection devices, such as pre-charging resistors and fuses, are integrated into the high-voltage box of the battery pack to reduce the risk of line damage and safety accidents and extend the service life of the battery and related electrical equipment.

[0117] Among them, the fuse can play the role of overload protection and short-circuit protection in the battery pack to prevent the circuit from being damaged under abnormal conditions to ensure the safety of the battery pack. The overload protection of the fuse includes that the fuse can be set with a rated current slightly higher than the normal working current, and the fuse can work at this rated current; when the current in the circuit exceeds the rated current of the fuse, the fuse will quickly melt and cut off the circuit to prevent overload damage to the component. The short-circuit protection of the fuse includes that when a short circuit occurs, the current in the circuit will rise sharply, and the fuse will immediately melt and cut off the circuit to prevent damage to the battery and component equipment during a short circuit.

[0118] like Figure 8 As shown, the battery pack 810 includes a pre-charge resistor R1 and a fuse F1, and the battery pack 820 includes a pre-charge resistor R2 and a fuse F2.

[0119] In order to more accurately control the execution of the circuit in the battery pack, the first battery pack and the second battery pack may include: a first switch, a first end of which is connected to the positive electrode of the first battery pack, and a second end is connected to the pre-charging resistor of the first battery pack; a second switch, a first end of which is connected to the negative electrode of the battery module of the first battery pack, and a second end is connected to the negative electrode of the first battery pack; a third switch, a first end of which is connected to the positive electrode of the second battery pack, and a second end is connected to the positive electrode of the battery module of the second battery pack; and a fourth switch, a first end of which is connected to the negative electrode of the battery module of the second battery pack, and a second end is connected to the negative electrode of the second battery pack.

[0120] Continue to combine Figure 8 , the first, second, third and fourth switches are K1, K2, K3 and K4 respectively; it should be understood that in another implementation method based on the above-mentioned swapping order of the first battery pack and the second battery pack, the first, second, third and fourth switches can also be K6, K4, K7 and K2 respectively.

[0121] During the power-on of the battery cluster (power-on of the battery cluster refers to connecting the battery cluster to the circuit to start supplying power, that is, the battery cluster starts working), in order to control the inrush current when the line starts and prevent arcing or excessive current shock when the line is connected to the high-voltage battery, the pre-charging process will be started first. As a way, the current in the line can be increased steadily through the pre-charging resistor.

[0122] like Figure 8 As shown, the battery cluster can be pre-charged based on R1. Based on this, the K1 switch is closed first, and then K2, K3 and K4 are closed. In the embodiment of the present disclosure, there is no restriction on the order of the three switches (i.e., the second, third and fourth switches) that are closed later. Therefore, the closing order of the latter three switches can have the following multiple possibilities as shown in Table 1.

[0123] Table 1

[0124]

[0125]

[0126] There are multiple switches involved in the circuit, and different closing sequences of switches during multiple closing processes may affect the synchronization of switch life. For example, the last closed switch is subjected to the greatest current shock, which has the greatest impact on its life. In order to avoid a single closing sequence causing premature aging of a switch, leading to system safety accidents. In the disclosed embodiment, the closing of multiple switches in the circuit can be carried out in a manner of rotating multiple closing sequences to improve the synchronization of the life of the switches in the energy storage system and avoid the emergence of the barrel effect.

[0127] As an example, the main BCU (such as BCU1) in the battery cluster can record the order of this closure (such as Plan A), and obtain the last closing method stored in the main BCU before closing the second, third, and fourth switches next time, and execute the unexecuted closing sequence in the table based on the last closing plan (that is, according to the order of plans ABCDEF in Table 1. Note that this order is only an example and is not a limitation). After all plans are executed, the cycle is repeated (Scheme A) to ensure that in the pre-charging process, the second, third, and fourth switches are subjected to a more balanced circuit pressure, thereby improving the aging synchronization of the three switches.

[0128] In addition, the battery cluster can also be pre-charged and powered up based on R2. In this case, the K6 switch is closed first, followed by K4, K7 and K2. Similar to the case of pre-charging and powering up based on R1, there is no restriction on the order of the three switches (i.e., the second, third and fourth switches) that are closed later. Optionally, the other three switches can be selected in a rotating manner to select the closing order to achieve aging synchronization of the switches.

[0129] For energy storage systems that require a larger pre-charge resistance, a method of pre-charging through multiple pre-charge resistors can be used. Figure 8 As shown, R1 and R2 can be used as pre-charging resistors at the same time for the pre-charging process. In this case, first close the K1 and K6 switches, and then close the K2 and K4 switches in sequence. It should be understood that the closure of the K2 and K4 switches can also be staggered. Compared with the method of pre-charging and powering up with a single pre-charging resistor, the method of pre-charging and powering up with a higher pre-charging resistance value (i.e., pre-charging and powering up with multiple pre-charging resistors at the same time) can further reduce the impact of the instantaneous impact of the current on the circuit and improve the safety of the circuit.

[0130] In the pre-charging process, if the pre-charging voltage is not reached within the preset time, the pre-charging process is exited and a second pre-charging can be performed as needed. When multiple pre-charging fails, the BCU in the battery cluster (i.e., the main BCU) can report the pre-charging fault so that the battery cluster can be repaired.

[0131] When the battery cluster reaches the pre-charge voltage, that is, when the line is boosted to a relatively stable voltage level based on the pre-charge resistor, the pre-charge resistor can be bypassed and the energy storage system begins the formal power-on process. As a method, the fifth switch is closed and the first switch is opened. The fifth switch refers to a switch whose first end is connected to the positive electrode of the first battery pack and whose second end is connected to the positive electrode of the battery module of the first battery pack.

[0132] Continue to combine Figure 8 When R1 is used as the pre-charge resistor, when the battery cluster reaches the pre-charge voltage, the switch K7 is closed, and then the switch K1 is opened, so that the current passes through the switch K7 to start the formal power-on process.

[0133] When R2 is used as the pre-charging resistor, when the battery cluster reaches the pre-charging voltage, the switch K3 is closed, and then the switch K6 is opened, so that the current passes through the switch K3, and the formal power-on process is carried out.

[0134] When R1 and R2 are used as pre-charging resistors at the same time, when the battery cluster reaches the pre-charging voltage, switches K7 and K3 are closed, and then switches K1 and K6 are opened, so that current passes through switches K7 and K3, and the formal power-on process is carried out.

[0135] It should be understood that the specific implementation of each switch in the battery pack is not limited in the embodiments of the present disclosure. For example, it can be an automatic switch (such as a relay) or a manual switch. In the embodiments of the present disclosure, the multiple switches involved in the same battery pack or between different battery packs in the same battery cluster can be switches of the same type or switches of different types.

[0136] When the battery cluster is powered off (powering off the battery cluster means disconnecting the battery cluster from the circuit so that it stops supplying power, that is, stops working), similar to what is mentioned above, there is no specific limitation on the disconnection order of multiple switches in the circuit. However, in order to avoid the current in the circuit under a single disconnection order causing significant damage to the last disconnected switch, multiple disconnection sequences can be used to rotate and cycle for disconnection. The possible disconnection sequences are shown in the following table. The specific rotation execution method is the same as the execution method when multiple switches are closed, so it will not be repeated here.

[0137] Table 2

[0138]

[0139]

[0140] In the disclosed embodiment, when the voltage difference between multiple battery clusters is large, in order to achieve precise voltage balance, a second voltage converter may be connected to the power end of each battery cluster (i.e., the positive output terminal of the second voltage converter is used as the positive terminal of each battery cluster, and the negative output terminal of the second voltage converter is used as the negative terminal of each battery cluster) to convert the output voltage of each battery cluster into the voltage required by the energy storage system, and / or convert the output current of each battery cluster into a current of appropriate size. That is, the second voltage converter can perform input and output power control according to the state of each battery cluster to ensure that each battery cluster operates in a safe state. This method makes it unnecessary for the energy storage system to consider factors such as voltage difference and current size during clustering. The type of the second voltage converter is similar to the first voltage converter mentioned above and will not be elaborated here. As an example, when the number of battery packs is small (or the parameter differences between the battery packs are large), it is impossible to screen out the number of battery packs that meet the requirements of the entire battery array. At this time, the battery clusters can be screened. Fig. 9 As shown, n battery packs that meet the conditions can be screened out from the battery packs, with a total of m groups screened, and then a second voltage converter (such as a DC-DC converter) is connected to the power end of the m battery clusters, so that each battery cluster can have an output voltage that reaches the voltage required by the energy storage system under the premise of safe operation, and / or an output current of an appropriate size, input and output power, etc.

[0141] For ease of understanding, the embodiments of the present disclosure are described in detail below by taking the transformation of retired automobile battery packs into energy storage battery arrays as an example.

[0142] like Fig.10 As shown, the energy storage battery array of the 1600V voltage platform is formed by connecting the battery cluster 1010 and the battery cluster 1020 in parallel. Among them, the battery cluster 1010 is formed by connecting the battery pack 1010 and the battery pack 1011 in series, and the output voltage is 1600V; in the battery cluster 1010, the battery pack 1010 is the first battery pack, and the battery pack 1011 is the second battery pack. Based on the above, the first switch is K1, the second switch is K2, and the third and fourth switches are located inside the second battery pack, that is, the battery pack 1011 ( Fig.10 not shown).

[0143] The battery cluster 1020 is composed of a battery pack 1020 and a DC-DC converter 1021. As shown in the figure, the positive and negative electrodes of the battery pack 1020 are respectively connected to the positive and negative electrodes of the input terminal of the DC-DC converter 1021, and the positive and negative electrodes of the battery cluster 1020 are respectively connected to the positive and negative electrodes of the output terminal of the DC-DC converter 1021. After the DC-DC converter 1021 boosts the voltage, the output voltage of the battery cluster 1020 also reaches 1600V.

[0144] like Fig.10 As shown, in the two battery clusters, both the battery packs and the battery packs and DC-DC converters are connected through power harnesses to transmit electrical energy, and the communication between the battery packs and battery clusters is achieved through CAN line connection.

[0145] During the power-on process of the energy storage battery array, in order to prevent instantaneous current from damaging the line, the first thing to do in each battery cluster is the pre-charging process. Fig.10 In the battery cluster 1010 shown, the pre-charging process may be performed based on R1 ; in the battery cluster 1020 , the pre-charging process may be performed based on R2 .

[0146] In the pre-charging process based on R1, the switch K1 is closed first, and then the switch K2 and the switches in the battery pack 1011 (ie, the third switch and the fourth switch) are closed in sequence.

[0147] In the pre-charging process based on R2, the switch K6 is closed first, and then the switch K4 is closed.

[0148] When the battery cluster 1010 reaches the pre-charge voltage, the switch K7 is closed, and then the switch K1 is opened, so that the battery cluster 1010 ends the pre-charge process and starts the formal power-on process.

[0149] When the battery cluster 1020 reaches the pre-charge voltage, the switch K3 is closed, and then the switch K6 is opened, so that the battery cluster 1020 ends the pre-charge process and starts the formal power-on process.

[0150] During the power-off process of the energy storage battery array, based on the battery cluster 1010 , the switches K7 , K2 , the third switch and the fourth switch are sequentially disconnected, and based on the battery cluster 1020 , the switches K3 and K4 are sequentially disconnected.

[0151] In the subsequent pre-charging process, the number of times each of the three switches closed in sequence in the line is finally closed is balanced.

[0152] In the subsequent power-off process, the number of times each of the four switches that are disconnected in sequence in the line is finally disconnected is also balanced.

[0153] It should be understood that in the embodiments of the present disclosure, "B corresponding to A" means that B is associated with A, and B can be determined according to A. However, it should also be understood that determining B according to A does not mean determining B only according to A, and B can also be determined according to A and / or other information.

[0154] It should be understood that the term "and / or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0155] It should be understood that in the various embodiments of the present disclosure, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present disclosure.

[0156] In the several embodiments provided in the present disclosure, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0157] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0158] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0159] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (digital subscriber line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that can be read by a computer or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a digital video disc (DVD)), or a semiconductor medium (eg, a solid state disk (SSD)).

[0160] The above is only a specific embodiment of the present disclosure, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. An energy storage system based on retired battery packs, characterized in that: include: A plurality of battery clusters connected in parallel, each of the plurality of battery clusters comprising a plurality of battery packs connected in series, or each of the plurality of battery clusters comprising one or more battery packs and a first voltage converter, the first voltage converter being used to control one or more of a voltage, a current and a power of the one or more battery packs; as well as A battery management system, electrically connected to the plurality of battery clusters, and configured to control the plurality of battery clusters to charge and discharge; The battery management system performs program updates via the CAN bus to update the original code of the battery pack to the energy storage code of the energy storage system.

2. The energy storage system according to claim 1, characterized in that: The battery management system is also used to control the parallel connection of the plurality of battery clusters, including: sorting the voltages of the plurality of battery clusters, and performing power-on control using the voltage at a middle position of the sorting as a reference voltage; According to the reference voltage, the battery cluster in the middle position of the sorting is merged into the power harness; Then, a battery cluster with a voltage closest to that of the power harness is integrated into the power harness until the multiple battery clusters are successfully connected in parallel.

3. The energy storage system according to claim 2, characterized in that: If there are a first battery cluster and a second battery cluster among the plurality of battery clusters, and a voltage difference between the first battery cluster and the power harness is consistent with a voltage difference between the second battery cluster and the power harness, the battery management system controls the first battery cluster and the second battery cluster to be simultaneously incorporated into the power harness.

4. The energy storage system according to claim 2, characterized in that: If there are a third battery cluster and a fourth battery cluster among the multiple battery clusters, the voltage of the third battery cluster is lower than the voltage of the fourth battery cluster, and the absolute value of the voltage difference between the third battery cluster and the power harness is the same as the absolute value of the voltage difference between the fourth battery cluster and the power harness, the battery management system first controls the third battery cluster to be incorporated into the power harness, and then controls the fourth battery cluster to be incorporated into the power harness.

5. The energy storage system according to any one of claims 1 to 4, characterized in that: Each of the plurality of battery packs connected in series comprises a pre-charging resistor, wherein during a power-on process of each battery cluster, one or more of the plurality of pre-charging resistors included in each battery cluster are used for pre-charging of each battery cluster.

6. The energy storage system according to any one of claims 1 to 4, characterized in that: During one power-on process of each battery cluster, the battery management system is used to control the closing of multiple switches; and during multiple power-on processes of each battery cluster, the closing order of the multiple switches is changed; The plurality of battery packs connected in series include a first battery pack and a second battery pack, and the plurality of switches include: a first switch, wherein a first end of the first switch is connected to the positive electrode of the first battery pack, and a second end of the first switch is connected to a pre-charging resistor of the first battery pack; a second switch, wherein a first end of the second switch is connected to the negative electrode of the battery module of the first battery pack, and a second end of the second switch is connected to the negative electrode of the first battery pack; a third switch, a first end of the third switch being connected to the positive electrode of the second battery pack, and a second end of the third switch being connected to the positive electrode of the battery module of the second battery pack; and A fourth switch, wherein a first end of the fourth switch is connected to the negative electrode of the battery module of the second battery pack, and a second end of the fourth switch is connected to the negative electrode of the second battery pack.

7. The energy storage system according to claim 6, characterized in that: When each battery cluster reaches the pre-charge voltage, the battery management system controls the closing of the fifth switch and then disconnects the first switch; wherein the first end of the fifth switch is connected to the positive electrode of the first battery pack, and the second end of the fifth switch is connected to the positive electrode of the battery module of the first battery pack.

8. The energy storage system according to claim 7, characterized in that: During one power-off process of each battery cluster, the battery management system is used to control the disconnection of the second switch, the third switch, the fourth switch and the fifth switch, and during multiple power-off processes of each battery cluster, the disconnection order between the second switch, the third switch, the fourth switch and the fifth switch is changed.

9. The energy storage system according to any one of claims 1 to 4, characterized in that: The battery management system includes a plurality of battery pack management units, each of which is electrically connected to a battery pack; the plurality of battery pack management units associated with each battery cluster include a master battery pack management unit and a slave battery pack management unit; Wherein, the energy storage code of the master battery pack management unit and the slave battery pack management unit are different; and / or The master battery pack management unit communicates with the slave battery pack management unit via a CAN bus; and / or The main battery pack management unit is used to control all battery packs in each battery cluster to charge and discharge and / or communicate with other battery pack management units.

10. The energy storage system according to any one of claims 1 to 4, characterized in that: Each of the battery clusters includes a plurality of battery packs connected in series, and a power end of each of the battery clusters includes a second voltage converter, and the second voltage converter is used to control one or more of the voltage, current and power of each of the battery clusters.

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