Battery pack and energy storage system

Abstract

The utility model relates to a battery pack and an energy storage system. The battery pack comprises a plurality of battery cells connected in series; a first energy storage module; the first power supply management module is respectively connected with the first energy storage module and each battery cell; the voltage acquisition module is connected with each battery cell and is used for detecting the voltage of each battery cell; the first-stage control module is connected with the voltage acquisition module and is used for determining the battery cell needing to be balanced according to the voltage of each battery cell and controlling the first power supply management module to transmit the electric energy of the battery cell needing to be balanced to the first energy storage module for storage; or the first power management module is controlled to transmit the electric energy in the first energy storage module to the battery cell needing to be balanced.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery pack and an energy storage system. Background Art

[0002] As the power of energy storage systems increases, more and more battery cells are required. During the operation and storage of energy storage systems, battery cell consistency problems such as voltage difference and power loss are prone to occur. For example, in practice, if the energy storage system is in low power mode for a long time, it will affect the consistency of the battery cells.

[0003] In order to solve the problem of cell consistency in energy storage systems, a combination of active balancing and passive balancing is generally used. However, the current balancing method has problems such as complex control logic, inability to accurately control the balanced energy during energy transfer, and low efficiency. Utility Model Content

[0004] Based on this, it is necessary to provide a battery pack and energy storage system to address the above technical problems.

[0005] In a first aspect, the present application provides a battery pack, comprising:

[0006] A plurality of battery cells connected in series;

[0007] A first energy storage module;

[0008] A first power management module is connected to the first energy storage module and each battery cell respectively;

[0009] The voltage acquisition module is connected to each battery cell respectively to detect the voltage of each battery cell;

[0010] The first-level control module is connected to the voltage acquisition module, and is used to determine the battery cells that need to be balanced according to the voltage of each battery cell, and control the first power management module to transfer the electric energy of the battery cells that need to be balanced to the first energy storage module for storage, or control the first power management module to transfer the electric energy in the first energy storage module to the battery cells that need to be balanced.

[0011] In a second aspect, the present application provides an energy storage system, comprising:

[0012] A plurality of battery clusters, each battery cluster comprising: a plurality of battery packs as described in the first aspect above connected in series.

[0013] One of the above technical solutions has the following advantages and beneficial effects:

[0014] By setting up an energy storage module in the battery pack as an energy transfer, the balancing efficiency can be improved, the complexity of balancing control can be reduced, and the accuracy of balancing can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of the architecture of an energy storage system according to an embodiment of the present application;

[0016] Figure 2 A circuit diagram of a battery pack according to an embodiment of the present application;

[0017] Figure 3 A circuit diagram of an energy storage system according to an embodiment of the present application;

[0018] Figure 4 This is a circuit diagram of an energy storage system according to another embodiment of the present application. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0020] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0021] In addition, the term "plurality" shall mean two or more than two. The term "exceeding" shall mean greater than or equal to.

[0022] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0023] See also Figure 1Schematic diagram of the architecture of the energy storage system of one embodiment of the present application. In one embodiment of the present application, the energy storage system includes: a plurality of battery clusters 1 and a junction box 2. The junction box 2 is used to collect the DC of each battery cluster 1 and transmit it to the PCS (Power Conversion System, energy storage converter). The junction box 2 includes: a UPS power supply 20 (Uninterruptible Power Supply), a resistive load 21 and a communication and power supply module 22. Among them, the UPS power supply 20 is used to provide uninterruptible power, which may include a plurality of batteries to provide uninterruptible power to the energy storage system. The number of batteries, for example, may be 4 or 6, for providing, for example, 3000W of power. The resistive load 21 is used to consume electrical energy when the energy storage system is passively balanced. The communication and power supply module 22 is used to connect to the battery cluster 1 to achieve communication and power supply with the battery cluster 1.

[0024] Each battery cluster 1 may include a plurality of battery packs 10, and each battery pack 10 may include a plurality of battery cells connected in series. For example, the energy storage system may include 8 battery clusters 1, each battery cluster 1 includes 8 battery packs 10, and each battery pack 10 includes 48 battery cells connected in series, so that the energy storage system can provide a voltage of 1500V.

[0025] Each battery cluster 1 is provided with a high voltage box 11. The high voltage box 11 is used to manage and control the battery cluster 1. Figure 1 After being connected in series, multiple battery packs 10 are connected to a high-voltage box 11 , and the high-voltage box 11 is then connected to the combiner cabinet 2 .

[0026] See also Figure 2 The circuit diagram of the battery pack of one embodiment of the present application is shown in FIG. As described above, each battery pack 10 includes a plurality of battery cells 101 connected in series and a battery cell management unit BMU. The battery cell management unit BMU is used to collect data of the battery cells in a single battery pack. The BMU includes: a first power management module 102, a first level control module 103, a voltage acquisition module 104, a first energy storage module 105, and a plurality of switches 106.

[0027] One end of each switch 106 is connected to the positive electrode of the battery cell 101, and the other end is connected to the first power management module 102. The first power management module 102 is connected to the first energy storage module 105. The first level control module 103 is connected to each switch 106 to control the switch-off of each switch 106 respectively.

[0028] The voltage acquisition module 104 is connected to each battery cell 101, respectively, and is used to detect the voltage of each battery cell 101. In one embodiment, the voltage acquisition module 104 may be an analog front end AFE chip.

[0029] The first-level control module 103 is connected to the voltage acquisition module 104, and is used to determine the battery cells that need to be balanced according to the voltage of each battery cell 101, and control the first power management module 102 to transfer the electric energy of the battery cells that need to be balanced to the first energy storage module 105 for storage, or control the first power management module 102 to transfer the electric energy in the first energy storage module 105 to the battery cells that need to be balanced.

[0030] Therefore, the first power management module 102 transfers the voltage of the battery cell that needs to be balanced to the first energy storage module 105, or outputs the corresponding voltage to the battery cell that needs to be balanced for supplementary power.

[0031] In one embodiment, the first-level control module 103 is used to control the on and off of the switch 106 connected to the battery cell that needs to be balanced, so as to control the first power management module 102 to transfer the electric energy of the battery cell that needs to be balanced to the first energy storage module 105 for storage, or to transfer the electric energy in the first energy storage module 105 to the battery cell that needs to be balanced.

[0032] In an embodiment of the present application, the first power management module 102 may include a plurality of pins, each of which is connected to a battery cell 101 through a switch 106 to ensure that each battery cell 101 can be charged and discharged independently. The switch 106 may be a semiconductor integrated switch. When balancing the battery cells 101, the switch 106 may serve as a redundant protection function. The first-level control module 103 may control the first power management module 102 through a signal to adjust the balancing current and perform balancing control more accurately.

[0033] It should be understood that the first-level control module 103 can also directly output a control signal to the first power management module 102, and the first power management module 102 controls the pins connected to the battery cells that need to be balanced, thereby transmitting the electric energy of the battery cells that need to be balanced to the first energy storage module 105 or transmitting the electric energy in the first energy storage module 105 to the battery cells that need to be balanced.

[0034] In one embodiment, the first-level control module 103 is also used to determine the number of battery cells that need to be balanced; when the number of battery cells that need to be balanced is within a set range, the first power management module 102 is controlled to transfer the electric energy of the battery cells that need to be balanced to the first energy storage module 105 for storage, or the first power management module 102 is controlled to transfer the electric energy in the first energy storage module 105 to the battery cells that need to be balanced.

[0035] The aforementioned setting range can be determined according to the total number of battery cells in the battery pack, for example, it can be set to one-third or one-quarter of the total number of battery cells. When the number of battery cells that need to be balanced exceeds the set range, active balancing and / or passive balancing can be directly adopted. In one embodiment, active balancing may be a balancing method in which the electric energy of a battery cell with a high voltage is transferred to a battery cell with a low voltage, or a battery cell with a low voltage is charged through an external power supply circuit. Passive balancing may be a method in which the electric energy of a battery cell with a high voltage is consumed through a resistive load. In the embodiments of the present application, active balancing and passive balancing are not limited.

[0036] In one embodiment of the present application, the battery cell that needs to be balanced is the battery cell whose voltage difference with other battery cells exceeds a preset value. The preset value can be set to 30mv, 50mv or 300mv, etc. according to actual conditions. That is, in the battery pack, if the voltage difference between a certain battery cell and other battery cells exceeds a preset value, for example, 30mv, then the battery cell can be determined as the battery cell that needs to be balanced.

[0037] The first power management module 102 is also used to obtain the power status of the first energy storage module 105. The first-level control module 103 is also used to control the resistive load to be connected to the battery cell that needs to be balanced when the power of the first energy storage module 105 is full, so as to consume the power of the battery cell that needs to be balanced. In one embodiment, the power of the first energy storage module 105 is full, which may refer to the power stored in the first energy storage module 105 reaching the set value. The set value may be the maximum value of the power that the first energy storage module 105 can store. For example, when the first energy storage module 105 is an energy storage capacitor, the set value is the voltage value when the first energy storage module 105 is fully charged. When the power of the first energy storage module 105 reaches the maximum value, it can no longer receive power, and the power of the battery cell that needs to be balanced is consumed through the resistive load. In this way, the safety of the first energy storage module 105 can be ensured.

[0038] In the embodiment of the present application, when a single-pack battery pack 10 is charged and discharged, if the voltage difference of the battery cells is too large, and only a few battery cells have a high voltage (i.e., exceeding a preset value), and the consistency of other battery cells is very high, the electric energy of the battery cells with a high voltage can be preferentially transferred to the first energy storage module 105 for storage. If the first energy storage module 105 is fully charged, the BMU passive balancing will be started, and the electric energy of the battery cells with a high voltage will be consumed by a resistive load, thereby reducing the voltage difference between the battery cells in the battery pack 10. Compared with the balancing method in the related art, by adding the first energy storage module 105 for energy storage instead of directly starting passive balancing, the balancing efficiency can be improved and the complexity of balancing control can be reduced.

[0039] In one embodiment of the present application, the battery cell that needs to be balanced is a battery cell whose voltage difference with the voltage of other battery cells is lower than a preset value. As mentioned above, the preset value can be set according to actual conditions.

[0040] The first power management module 102 is also used to obtain the power status of the first energy storage module 105. The first-level control module 103 is also used to control the external power supply circuit to provide power to the battery cells that need to be balanced when the power of the first energy storage module 105 is insufficient. In one embodiment, the external power supply circuit can be a circuit that provides power to the BMU of the battery pack.

[0041] Therefore, when the single-pack battery pack 10 is charged and discharged, if the voltage difference of the battery cells is too large, and only a few battery cells have low voltage (i.e., lower than the preset value), and the consistency of other battery cells is very high, the low-voltage battery cells are supplemented with power through the first energy storage module 105. If the power of the first energy storage module 105 is insufficient, active balancing will be performed through the external power supply circuit of the BMU. Compared with the method of directly transferring the power of the high-cell to the power of the low-cell or directly supplementing the power through the external power supply circuit in the related art, the balancing method of the embodiment of the present application can use the energy previously stored in the first energy storage module 105 for active balancing, reduce the power consumption of the external power supply circuit, save energy, and at the same time, the control strategy is simple and more flexible and accurate.

[0042] See also Figure 3 FIG. 1 is a circuit diagram of an energy storage system according to an embodiment of the present application. In the embodiment of the present application, the energy storage system includes a plurality of battery clusters. Each battery cluster includes a plurality of battery packs 10 and a high-voltage box 11. The circuit diagram of the plurality of battery packs 10 is as follows: Figure 2 As shown, no further details are given here.

[0043] In one embodiment, the high voltage box 11 includes: a second power management module 111 , a second level control module 112 , a second energy storage module 113 and an input / output interface 114 .

[0044] Among them, the input-output interface 114 includes an input end and an output end. The input end is connected to the battery pack in the battery cluster, and the output end is connected to the combiner cabinet. The input end is used to connect to the positive and negative electrodes of the battery cells connected in series. In one embodiment, the input end includes: interfaces B+ and B-, which are respectively used to connect to the positive and negative electrodes of the battery pack. The output end is used to connect to the combiner cabinet. In one embodiment, the output end includes interfaces P+ and P-, which are used to connect to the combiner cabinet 2 to transmit the electric energy of the battery cell to the combiner cabinet 2.

[0045] The input / output interface 114 also includes: a switch, a pre-charging resistor, a circuit breaker, a contactor, and a fuse. When the switch is closed, the input and output terminals are connected. The contactor is connected in parallel with the pre-charging resistor. When the contactor is closed, the pre-charging resistor is connected to reduce the current impact when the high-voltage box is connected. The circuit breaker is used to cut off and connect the load circuit to selectively cut off the load circuit. The fuse may include a fuse, which is used to melt in abnormal conditions such as overvoltage and overcurrent to ensure the safety of the high-voltage box.

[0046] The second power management module 111 is respectively connected to the second-stage control module 112 , the second energy storage module 113 , and the first power management module 102 in each battery pack.

[0047] The second power management module 111 is used to perform the transfer of electric energy, for example, converting the electric energy of the second energy storage module 113 into a corresponding voltage and transmitting it to the battery cells in the battery pack 10 for recharging, or transmitting the voltage of the battery cells in the battery pack 10 to the second energy storage module 113 for storage.

[0048] The second-level control module 112 is communicatively connected to the first-level control module 103 , for example, via a CAN bus, to exchange control information and data.

[0049] See also Figure 4 The second-level control modules 112 in each battery cluster are connected to each other and to the communication and power supply module 22 in the combiner cabinet 2 to achieve information exchange and control.

[0050] See also Figure 4 In one embodiment of the present application, the high voltage box 11 further includes:

[0051] The voltage-stabilized power supply module 115 is respectively connected to the second power management module 111, the second-level control module 112 and the communication and power supply module 22, and is used to convert 220V AC power into DC power for use by the internal components of the high-voltage box 11;

[0052] The high-voltage box balancing port 116 is connected to the second power management module 111 and the communication and power supply module 22 respectively, and is used to receive electric energy from the junction box 2 or other high-voltage boxes and transmit it to the second power management module 111, or transmit the electric energy to other high-voltage boxes during the balancing process.

[0053] The output interfaces P+ and P- in the high-voltage box 11 in each battery cluster 1 are used to connect to the interfaces B+ and B- in the combiner cabinet 2 to combine the electric energy of the battery cells to the combiner cabinet. In one embodiment, after the combiner cabinet 2 combines, the electric energy is transmitted to the PCS through the interfaces P+ and P-, and the PCS converts the DC power into AC power and integrates it into the power grid.

[0054] In one embodiment of the present application, the first energy storage module 105 and the second energy storage module 113 may include one or more capacitors. Multiple capacitors may be connected in series or in parallel. The number of capacitors may be matched and selected according to the number of cells in the battery pack. In one embodiment, the capacitor may be a supercapacitor. Using a supercapacitor as an energy storage medium, the capacitor has a fast charging and discharging speed, and has almost no loss as an electrical energy storage medium. The number of cycles and service life are far superior to electrochemical energy storage, which can reduce the overall active balancing failure rate.

[0055] When a single battery pack is charged and discharged in the energy storage system, the above combination is used Figure 2 The cell balancing method is not described here in detail. It should be understood that charging and discharging a single battery pack can be applied in the testing and production process of the energy storage system.

[0056] When the energy storage system is charging and discharging, the first-level control module 103 is used to determine the battery cells that need to be balanced according to the voltage of each battery cell, and control the first power management module 102 to transfer the electric energy of the battery cells that need to be balanced to the first energy storage module 105 for storage, or control the first power management module 102 to transfer the electric energy in the first energy storage module 105 to the battery cells that need to be balanced.

[0057] In one embodiment, the first-level control module 103 is also used to determine the number of cells that need to be balanced; when the number of cells that need to be balanced is within a set range, the first power management module 102 is controlled to transfer the electric energy of the cells that need to be balanced to the first energy storage module 105 for storage, or the first power management module 102 is controlled to transfer the electric energy in the first energy storage module 105 to the cells that need to be balanced. The aforementioned setting range can be determined according to the total number of cells in the battery pack, for example, set to one third or one fourth of the total number of cells.

[0058] In one embodiment, the battery cell that needs to be balanced is a battery cell whose voltage difference with other battery cells exceeds a preset value. As mentioned above, the preset value can be set according to actual conditions. When the first energy storage module 105 is fully charged, the first-level control module 103 is also used to control the first power management module 102 to transfer the power of the battery cell that needs to be balanced to the second power management module 111. The second-level control module is used to control the second power management module to transfer the received power to the second energy storage module 113 for storage. Further, when the second energy storage module 113 is fully charged, the second-level control module 112 is also used to control the second power management module to transfer the received power to the UPS power supply for discharge. In one embodiment, when the UPS power supply is fully charged, the second-level control module 112 is also used to control the resistive load in the junction box to be connected to the battery cell that needs to be balanced to consume the power of the battery cell that needs to be balanced.

[0059] Therefore, in the embodiment of the present application, when the energy storage system is charging and discharging, if only a few cells (i.e., the number of cells that need to be balanced is within the set range) have a high voltage (i.e., exceeds the preset value), and the consistency of other cells is very high, the electric energy will be preferentially transferred to the first energy storage module 105 for storage; if the first energy storage module 105 is fully charged, the electric energy will be transferred to the second energy storage module 113 inside the high-voltage box through the wire for storage; if the second energy storage module 113 is fully charged, the high-voltage box will discharge to the UPS power supply in the junction box. In this way, small energy can be gathered into more energy for storage.

[0060] In one embodiment, the cell that needs to be balanced is a cell whose voltage difference with other cells is lower than a preset value. The first level control module 103 is used to control the first power management module 102 to transfer the electric energy in the first energy storage module 105 to the cell that needs to be balanced.

[0061] In one embodiment, when the power of the first energy storage module 105 is insufficient, the first level control module communicates with the second level control module 112, so that the second level control module 112 controls the second power management module to transmit the power of the second energy storage module 113 to the battery cells that need to be balanced. The power of the second energy storage module 113 can be first transmitted to the first energy storage module 105, and then transmitted by the first energy storage module 105 to the battery cells that need to be balanced.

[0062] In one embodiment, when the power of the second energy storage module 113 is insufficient, the second-level control module 112 communicates with the combiner cabinet so that the UPS power supply in the combiner cabinet provides power to the second energy storage module 113 to transmit power to the battery cells that need to be balanced. The power of the second energy storage module 113 can be first transmitted to the first energy storage module 105, and then transmitted by the first energy storage module 105 to the battery cells that need to be balanced.

[0063] Therefore, in the embodiment of the present application, when the energy storage system is charging and discharging, if only a few battery cells have low voltage (i.e., lower than the preset value) and the consistency of other battery cells is very high, the first energy storage module 105 in the BMU will be used for discharge first to supplement the low-voltage battery cells; if the first energy storage module 105 in the BMU is insufficient and cannot meet the discharge requirements, the second energy storage module 113 in the high-voltage box will be discharged to the first energy storage module 105 in the battery pack, and then the first energy storage module 105 will supplement the battery cells. If the second energy storage module 113 in the high-voltage box is insufficient, power will be taken from the UPS power supply in the junction cabinet and stored in the second energy storage module 113 in the high-voltage box, and then the second energy storage module 113 will discharge to the first energy storage module 105 in the BMU, and then the first energy storage module 105 will discharge to the battery cells that need to be balanced.

[0064] In one embodiment, the cells that need to be balanced are all the cells in a single battery pack, that is, the voltage difference between the cells in a battery pack and the voltage of the cells in other clusters in the battery cluster exceeds the preset value. Then, the second-level control module 112 is also used to control the second power management module to transfer the received power to the second energy storage module in the high-voltage box of the adjacent battery cluster for storage when the power of the second energy storage module 113 is full. In one embodiment, when the power of the second energy storage module in the high-voltage box of the adjacent battery cluster is full, the second-level control module 112 is also used to control the second power management module 111 to transfer the received power to the UPS power supply for discharge. In one embodiment, when the UPS power supply is fully charged, the second-level control module 112 is also used to control the resistive load to be connected to the cells that need to be balanced to consume the power of the cells that need to be balanced.

[0065] It should be understood that adjacent battery clusters may be battery clusters having a circuit connection relationship or battery clusters that are adjacent to each other. Figure 1 As shown, two adjacent battery clusters are adjacent battery clusters.

[0066] Therefore, in an embodiment of the present application, when the energy storage system is charging and discharging, if the voltage of the entire cluster of single-pack battery packs is too high (i.e., exceeds the preset value) and the consistency of other battery packs is good, the single-pack battery packs discharge to the second energy storage module 113 in the high-voltage box through the BMU; when the second energy storage module 113 in the high-voltage box is fully charged, it discharges to the second energy storage module in the high-voltage box of the adjacent battery cluster; if the second energy storage module in the adjacent high-voltage box is fully charged, it discharges from the high-voltage box to the UPS power supply in the junction cabinet; if the UPS power supply is fully charged, the passive balancing function is started to consume the electric energy of the battery cells that need to be balanced through the resistive load.

[0067] In one embodiment, the cells to be balanced are all the cells in a battery pack, and the voltage difference between all the cells in the battery pack and the voltage of the cells in other battery packs is lower than a preset value. The second-level control module 112 is also used to control the external power supply to provide power to the cells in the battery pack.

[0068] Therefore, in an embodiment of the present application, when the energy storage system is charging and discharging, if the voltage of an entire cluster of single-pack battery packs is low (i.e., lower than a preset value), and the consistency of other battery packs is good, the entire pack can be actively balanced through the BMU. In addition, in order to improve efficiency, an external power supply provided by a junction cabinet provides electrical energy to the cells in the battery pack. In one embodiment, the external power supply may first transmit electrical energy to the high-voltage box, and the second-level control module 112 in the high-voltage box controls the second power management module 111 to transmit electrical energy to all cells in the battery pack. Thus, each cell in the battery pack is directly charged, and active balancing of the entire pack is efficiently achieved.

[0069] In the embodiment of the present application, by setting the energy storage module in the high-voltage box and combining it with the UPS power supply in the junction cabinet, active balancing can be performed within the package, within the cluster, and between clusters, so as to realize simple call and full utilization of balanced electric energy. And while integrating active balancing, the passive balancing function of resistive load is retained, which can not only reduce the complexity of the balancing algorithm, but also reduce the energy waste caused by passive balancing.

[0070] In the related art, active balancing can only be transferred directly from one battery cell, one pack, or one cluster to another battery cell, another pack, or another cluster. If the voltage of only a few battery cells, a few battery packs, or a few battery clusters is too high, since there is no passive balancing function, if these battery cells, battery packs, or battery clusters are discharged, the original consistency will be destroyed, making the control strategy complicated; and if passive balancing is adopted and resistive loads are used for consumption, energy will be wasted. In the embodiment of the present application, when the number of battery cells to be balanced is within the set range, or the voltage of the entire cluster of single battery packs is too low or too high, and the consistency of other battery cells or battery packs is high, the first energy storage module 105 and the second energy storage module 113 are used to store or supplement electric energy, which can effectively solve the problem of high voltage discharge, improve the balancing efficiency, and reduce the complexity of balancing.

[0071] In the embodiment of the present application, by integrating the energy storage module in the BMU unit board as an energy transfer station for active balancing; and by setting the energy storage module in the high-voltage box, and combining with the UPS power supply in the junction cabinet, active balancing within the package, within the cluster, and between clusters can be performed. That is, in the embodiment of the present application, three-level energy storage is adopted, the energy storage module is integrated in the BMU board itself as an energy temporary storage medium, the energy storage module is integrated in the high-voltage box as an energy temporary storage medium, and the UPS function is exerted in the charging and discharging of the junction cabinet, so that the UPS directly participates in the active balancing function, and realizes the simple call and full utilization of electric energy. And while integrating active balancing, the function of passive balancing of resistive loads is retained. Therefore, the embodiment of the present application can solve the problems of the complexity of the algorithm for direct energy transfer by active balancing in the related art, the waste of energy caused by passive balancing, and the inability to simultaneously include the active balancing and passive balancing functions in the related art.

[0072] Therefore, in the embodiment of the present application, the voltage difference of the battery cells that need to be balanced can be set to the millivolt (mv) level, which can solve the problem in the related art that when the voltage difference between clusters is greater than 20V, the single cluster maintenance function needs to be manually enabled, and when the voltage difference between clusters is less than 20V, the circulation current needs to be suppressed by pre-charging resistors, and the control logic is lagging. By using the energy storage technology of the high-voltage box, the voltage difference between clusters can be adjusted in advance through an active balancing solution. The voltage difference exceeding 20V can also be adjusted by active balancing technology, which is simpler and more convenient than the BMS design in the related art.

[0073] In addition, if the energy storage system is not connected to the grid for a long time, causing the system SOC to decrease and a power-deficient state to occur, the problem of power-deficient batteries due to long-term storage can be solved by replenishing the batteries in the embodiments of the present application.

[0074] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0075] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A battery pack, characterized in that: include: A plurality of battery cells connected in series; A first energy storage module; A first power management module is connected to the first energy storage module and each battery cell respectively; The voltage acquisition module is connected to each battery cell respectively to detect the voltage of each battery cell; The first-level control module is connected to the voltage acquisition module, and is used to determine the battery cells that need to be balanced according to the voltage of each battery cell, and control the first power management module to transfer the electric energy of the battery cells that need to be balanced to the first energy storage module for storage, or control the first power management module to transfer the electric energy in the first energy storage module to the battery cells that need to be balanced.

2. The battery pack according to claim 1, characterized in that: The battery pack further comprises: a plurality of switches; one end of each switch is connected to the positive electrode of a battery cell, and the other end is connected to the first-level control module; The first-level control module is used to control the on and off of the switch connected to the battery cell that needs to be balanced, so that the first power management module transfers the electric energy of the battery cell that needs to be balanced to the first energy storage module for storage or transfers the electric energy in the first energy storage module to the battery cell that needs to be balanced.

3. The battery pack according to claim 1 or 2, characterized in that: The first-level control module is further used to control the resistive load to be connected to the battery cell that needs to be balanced when the first energy storage module is fully charged with electric energy, so as to consume the electric energy of the battery cell that needs to be balanced.

4. The battery pack according to claim 1 or 2, characterized in that: The first-level control module is further used to control the external power supply circuit to provide power to the battery cells that need to be balanced when the power of the first energy storage module is insufficient.

5. An energy storage system, characterized in that: include: A plurality of battery clusters, each battery cluster comprising: a plurality of battery packs as described in any one of claims 1 to 4 connected in series.

6. The energy storage system according to claim 5, characterized in that: The energy storage system further includes: a combiner cabinet; each of the battery clusters further includes: a high-voltage box, the high-voltage box including: an input end, an output end, a second-level control module, a second power management module, and a second energy storage module; The input end is connected to the battery pack in the battery cluster; The output end is connected to the combiner cabinet; The second power management module is respectively connected to the second-level control module, the second energy storage module and the first power management module in each battery pack; The second-level control module is respectively connected to the first-level control module in each battery pack; The first-level control module is used to control the first power management module to transfer the power of the battery cells that need to be balanced to the second power management module when the power of the first energy storage module is fully stored; The second-level control module is used to control the second power management module to transmit the received electric energy to the second energy storage module for storage; or The first-level control module is used to communicate with the second-level control module when the first energy storage module is short of power, so that the second-level control module controls the second power management module to transfer the power in the second energy storage module to the battery cells that need to be balanced.

7. The energy storage system according to claim 6, characterized in that: The second-level control module is also used to control the second power management module to transmit the received power to the UPS power supply in the combiner cabinet for discharge when the second energy storage module is fully charged with power.

8. The energy storage system according to claim 7, characterized in that: When the UPS power supply is fully charged, the second-level control module is also used to control the resistive load in the combiner cabinet to be connected to the battery cells that need to be balanced, so as to consume the electric energy of the battery cells that need to be balanced.

9. The energy storage system according to claim 6, characterized in that: When the second energy storage module is short of power, the second-level control module is also used to communicate with the combiner cabinet so that the UPS power supply in the combiner cabinet provides power to the second energy storage module to transmit power to the battery cells that need balancing.

10. The energy storage system according to claim 6, characterized in that: The battery cells that need to be balanced are all the battery cells in a battery pack; The second-level control module is also used to control the second power management module to transmit the received electric energy to the second energy storage module in the high-voltage box of the adjacent battery cluster for storage when the electric energy of the second energy storage module is fully stored.

11. The energy storage system according to claim 10, characterized in that: When the electric energy of the second energy storage module in the high-voltage box of the adjacent battery cluster is fully stored, the second-level control module is also used to control the second power management module to transmit the received electric energy to the UPS power supply in the combiner cabinet for discharge; When the UPS power supply is fully charged, the second-level control module is also used to control the connection of the resistive load to the battery cells that need to be balanced to consume the power of the battery cells that need to be balanced.

12. The energy storage system according to claim 6, characterized in that: The battery cells that need to be balanced are all the battery cells in a battery pack; The second-level control module is also used to control the external power supply to provide electrical energy to the cells in the battery pack.

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