Battery cluster and energy storage system

Abstract

The battery cluster comprises a battery control unit, a one-way direct-current transformer and a plurality of battery modules, the output end of the one-way direct-current transformer is electrically connected with the first bus, and the input end of the one-way direct-current transformer is electrically connected with the second bus; wherein the working voltage of the second bus is higher than that of the first bus; the plurality of battery modules are connected in series and then are electrically connected with the second bus; each battery module comprises a battery assembly, a first bidirectional direct current converter and a battery management unit; in each battery module, the first bidirectional direct current converter is electrically connected with the first bus and the battery assembly, the battery management unit is electrically connected with the battery assembly and the first bus, and the battery management unit is further in communication connection with the battery control unit.

Description

Technical Field

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

[0002] In the prior art, commonly used battery cluster structures are as follows Figure 1 During long-term use or when new and old battery cells are mixed, uneven power between battery cells leads to problems such as shortened battery cluster life and reduced performance. Excessive voltage difference between battery cells leads to the problem that battery cells cannot be used in parallel, affecting the energy efficiency of the battery cluster. To this end, it is necessary to connect a high-power bidirectional DC transformer to each battery cell, and the battery cell is connected to the high-voltage bus through a high-power bidirectional DC transformer. Each bidirectional DC transformer is used to convert the working voltage of each battery cell into the same or approximately the same working voltage to realize power supply to the high-voltage bus. However, each battery cell is equipped with a high-power bidirectional DC transformer, which leads to a high cost of the battery cluster. In addition, the high-power bidirectional DC transformer is large in size and occupies more space, which reduces the volume energy density of the battery cluster. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide a battery cluster and an energy storage system, which improve technical problems caused by large differences in battery cell capacity or voltage, or by mixing new and old battery cells, through low-cost solutions.

[0004] The present application provides a battery cluster, comprising: a battery control unit, a unidirectional DC transformer and a plurality of battery modules; the output end of the unidirectional DC transformer is electrically connected to a first bus, and the input end of the unidirectional DC transformer is electrically connected to a second bus; wherein the operating voltage of the second bus is higher than the operating voltage of the first bus; the plurality of battery modules are connected in series and electrically connected to the second bus, and each battery module comprises: a battery assembly, a first bidirectional DC converter, and a battery management unit; in each battery module: the first bidirectional DC converter is electrically connected to the first bus and the battery assembly, respectively, the battery management unit is electrically connected to the battery assembly and the first bus, and the battery management unit is also communicatively connected to the battery control unit.

[0005] In one or more embodiments, the battery control unit is configured to: in response to the capacity difference between the first battery assembly and the second battery assembly being greater than or equal to a capacity threshold, control the first bidirectional DC converter of the first battery module to discharge the first battery assembly, and control the first bidirectional DC converter of the second battery module to charge the second battery assembly, so that the first battery assembly transmits electrical energy to the second battery assembly through the first bus; wherein the first battery assembly is the battery assembly with the largest capacity among the multiple battery assemblies, the second battery assembly is the battery assembly with the smallest capacity among the multiple battery assemblies, the first battery assembly is the battery assembly of the first battery module, and the second battery assembly is the battery assembly of the second A battery assembly of a battery module; and / or, in response to a voltage difference between a third battery assembly and a fourth battery assembly being greater than or equal to a voltage threshold, controlling the first bidirectional DC converter of the third battery module to discharge the third battery assembly, and controlling the first bidirectional DC converter of the fourth battery module to charge the fourth battery assembly, so that the third battery assembly transmits electric energy to the fourth battery assembly through the first bus; wherein the third battery assembly is a battery assembly with the largest voltage among the multiple battery assemblies, the fourth battery assembly is a battery assembly with the smallest voltage among the multiple battery assemblies, the third battery assembly is a battery assembly of the third battery module, and the fourth battery assembly is a battery assembly of the fourth battery module.

[0006] In one or more embodiments, the first bidirectional DC converter is also connected to the battery control unit for communication, and is configured to charge or discharge the battery assembly belonging to the same battery module as the first bidirectional DC converter in response to the control of the battery control unit.

[0007] In one or more embodiments, the communication between the first bidirectional DC converter and the battery control unit includes CAN bus communication or daisy chain communication; and / or, the communication between the battery management unit and the battery control unit includes CAN bus communication or daisy chain communication.

[0008] In one or more embodiments, it further includes: a second bidirectional DC converter; a first end of the second bidirectional DC converter is electrically connected to the battery assembly, and a second end of the second bidirectional DC converter is electrically connected to the second bus.

[0009] In one or more embodiments, the rated output power of the second bidirectional DC converter is greater than the rated output power of the first bidirectional DC converter.

[0010] In one or more embodiments, the rated output power of the first bidirectional DC converter is: 200W~600W; and / or, the rated output power of the second bidirectional DC converter is: 3000W~150KW.

[0011] In one or more embodiments, the battery control unit is configured to perform the following steps: S1. Calculate the average capacity of multiple battery assemblies; S2. In response to the capacity difference between the first battery assembly and the second battery assembly being greater than or equal to the capacity threshold, control the first bidirectional DC converter of the first battery module and the second battery module to enable the first battery assembly to transmit electrical energy to the second battery assembly through the first bus until the capacity of the first battery assembly or the capacity of the second battery assembly reaches the average capacity; S3. Based on the current capacity of each battery assembly, redetermine the first battery assembly and the second battery assembly, return to steps S1 and S2 and continue to execute until the capacity difference between each battery assembly The capacity difference is less than the capacity threshold; and / or, A1. Calculate the average voltage of each battery assembly; A2. In response to the difference between the voltage of the third battery assembly and the voltage of the fourth battery assembly being greater than or equal to the voltage threshold, control the first bidirectional DC converter of the third battery module and the fourth battery module to enable the third battery assembly to transmit electrical energy to the fourth battery assembly through the first bus until the voltage of the third battery assembly or the voltage of the fourth battery assembly reaches the average voltage; A3. Based on the current voltage of each battery assembly, redetermine the third battery assembly and the fourth battery assembly, return to steps A1 and A2 to continue executing until the voltage difference between each battery assembly is less than the voltage threshold.

[0012] In one or more embodiments, the first bus is a 24V Bus line, and the second bus is a DC bus.

[0013] In one or more embodiments, it includes: a first energy storage converter electrically connected to the second bus.

[0014] An embodiment of the present application further provides an energy storage system, comprising any battery cluster in the present application, wherein a plurality of battery clusters are connected in parallel; the first busbars of the battery clusters are electrically connected, and the battery control units in the battery clusters are communicatively connected.

[0015] In one or more embodiments, the system includes: a second energy storage converter electrically connected to a plurality of battery clusters.

[0016] In one or more embodiments, each battery cluster includes a first energy storage converter electrically connected to the second bus bar.

[0017] In one or more embodiments, the plurality of battery control units are further configured to: in response to a capacity difference between the fifth battery assembly and the sixth battery assembly being greater than or equal to a capacity threshold, control the first bidirectional DC converter of the fifth battery module to discharge the fifth battery assembly, and control the first bidirectional DC converter of the sixth battery module to charge the sixth battery assembly, so that the fifth battery assembly transmits electrical energy to the sixth battery assembly through the first bus; wherein the fifth battery assembly is the battery assembly with the largest capacity in the energy storage system, the sixth battery assembly is the battery assembly with the smallest capacity in the energy storage system, the fifth battery assembly is the battery assembly of the fifth battery module, and the sixth battery assembly is the battery assembly of the sixth battery module. A battery assembly of a sixth battery module; and / or, in response to a voltage difference between a seventh battery assembly and an eighth battery assembly being greater than or equal to a capacity threshold, controlling the first bidirectional DC converter of the seventh battery module to discharge the seventh battery assembly, and controlling the first bidirectional DC converter of the eighth battery module to charge the eighth battery assembly, so that the seventh battery assembly transmits electrical energy to the eighth battery assembly through the first bus; wherein the seventh battery assembly is the battery assembly with the largest voltage in the energy storage system, the eighth battery assembly is the battery assembly with the smallest voltage in the energy storage system, the seventh battery assembly is the battery assembly of the seventh battery module, and the eighth battery assembly is the battery assembly of the eighth battery module.

[0018] In one or more embodiments, the plurality of battery control units are configured to: in response to a capacity difference between the first battery cluster and the second battery cluster being greater than or equal to a capacity threshold, control the first bidirectional DC converter of the first battery cluster to discharge the first battery cluster, and control the first bidirectional DC converter of the second battery cluster to charge the second battery cluster, so that the first battery cluster transmits electrical energy to the second battery cluster through the first bus; wherein the first battery cluster is a battery cluster with the largest capacity among the plurality of battery clusters, and the second battery cluster is a battery cluster with the smallest capacity among the plurality of battery clusters; and / or, in response to a voltage difference between the third battery cluster and the fourth battery cluster being greater than or equal to a voltage threshold, control the first bidirectional DC converter of the third battery cluster to discharge the third battery cluster, and control the first bidirectional DC converter of the fourth battery cluster to charge the fourth battery cluster, so that the third battery cluster transmits electrical energy to the fourth battery cluster through the first bus; wherein the third battery cluster is a battery cluster with the largest voltage among the plurality of battery clusters, and the fourth battery cluster is a battery cluster with the smallest voltage among the plurality of battery assemblies.

[0019] Beneficial effects of the embodiments of the present application:

[0020] In the battery cluster of the embodiment of the present application, the first bus and the first bidirectional DC converter are used to balance the power / voltage of each battery assembly in the battery cluster, so that the power / voltage of each battery assembly is close to each other, and the parallel condition is met, so that each battery assembly is used in parallel, and the use efficiency of the battery cluster is improved. When the working voltage of the first bus is lower than the working voltage of the second bus, the manufacturing cost, operating power and energy loss of the first bidirectional DC converter are all lower than those of the high-power bidirectional DC converter in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other embodiments can also be obtained based on these drawings.

[0022] Figure 1 A schematic diagram of a battery module in the related art;

[0023] Figure 2 This is a first schematic diagram of a battery cluster in an embodiment of the present application;

[0024] Figure 3 This is a second schematic diagram of a battery cluster in an embodiment of the present application;

[0025] Figure 4 This is a third schematic diagram of a battery cluster in an embodiment of the present application;

[0026] Figure 5 This is a fourth schematic diagram of a battery cluster in an embodiment of the present application;

[0027] FIG6 (a) is a first flow chart of a battery control unit in a battery cluster according to an embodiment of the present application configured to execute;

[0028] FIG6( b ) is a second flow chart of the battery control unit in the battery cluster according to an embodiment of the present application being configured to execute;

[0029] Figure 7 This is a fifth schematic diagram of a battery cluster according to an embodiment of the present application;

[0030] Figure 8 This is a first schematic diagram of an energy storage system in an embodiment of the present application;

[0031] Fig. 9 This is a second schematic diagram of the energy storage system in the embodiment of the present application;

[0032] Fig.10 This is a third schematic diagram of the energy storage system in the embodiment of the present application. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present application to clearly and in detail describe the technical solutions 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. The technical features involved in different embodiments of the present application can be combined with each other as long as they do not conflict with each other.

[0034] It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or one or more intermediate elements can exist between them. When an element is described as being "connected to" another element, it can be directly connected to the other element, or one or more intermediate elements can exist between them.

[0035] In the related technology, commonly used battery modules are as follows Figure 1 , the unidirectional DC transformer converts the voltage on the high-voltage bus into 24V voltage, and the 24V Bus line (bus) supplies power to the battery control unit and each battery management unit. In addition, the high-voltage bus is also responsible for the external power supply of the battery cluster. In some cases, the models of the battery cells are the same, but during long-term use, the aging conditions of the battery cells are different, resulting in inconsistent power / capacity / voltage performance between the battery cells, and some even have large differences; in other cases, there are conditions where new and old battery cells are mixed, and the difference in power / capacity / voltage between the new battery cells and the old battery cells is more obvious after being fully charged. In order to solve the problem of mixed use of new and old battery cells and unbalanced battery cells, the relevant technology connects a high-power bidirectional DC transformer to each battery cell. The above-mentioned high-power bidirectional DC transformer is responsible for the external power supply of the battery cell on the one hand, and for charging the battery cell on the other hand. However, high-power bidirectional DC transformers usually need to increase the voltage of the battery cells to 120V-1500V because they need to supply power to the high-voltage bus. The greater the voltage increase ratio, the more turns of the coil in the bidirectional DC transformer, the higher its volume and production cost, and the greater its power consumption, which reduces the energy conversion efficiency, ultimately leading to higher cost of the battery cluster and lower energy utilization.

[0036] In order to improve the above technical problems, the embodiments of the present application provide a battery cluster and an energy storage system, which are described in detail below.

[0037] The present application embodiment provides a battery cluster, see Figure 2 ,include:

[0038] A battery control unit 101, a unidirectional DC transformer 201 and a plurality of battery modules 300;

[0039] The output end of the unidirectional DC transformer 201 is electrically connected to the first bus 401, and the input end of the unidirectional DC transformer 201 is electrically connected to the second bus 402; wherein the operating voltage of the second bus 402 is higher than the operating voltage of the first bus 401;

[0040] A plurality of battery modules 300 are connected in series and electrically connected to a second bus bar 402 , and each battery module 300 includes: a battery assembly 301 , a first bidirectional DC converter 302 , and a battery management unit 303 ;

[0041] In each battery module 300: the first bidirectional DC converter 302 is electrically connected to the first bus 401 and the battery assembly 301 corresponding to the first bidirectional DC converter 302, respectively; the battery management unit 303 is electrically connected to the battery assembly 301 and the first bus 401, respectively; the battery management unit 303 is also communicatively connected to the battery control unit 101 via a communication line 403.

[0042] In some embodiments of the present application, the battery control unit 101 is a BCU (Battery Control Unit), the first bidirectional DC converter 302 is a bidirectional DC converter, the BCU manages the entire battery cluster, the BCU communicates with the battery management unit 303 through a communication line 403, obtains parameter information of the battery module (including temperature, voltage, power, etc.), and manages each battery assembly 301, the BCU communicates with the first bidirectional DC converter 302 through the communication line 403, and controls the first bidirectional DC converter 302 to charge and discharge the battery assembly 301, so that the battery assembly with high power / capacity / voltage transmits power to the battery assembly with low power / capacity / voltage. The battery management unit 303 is a BMU (Battery Management Unit). The battery assembly 301 is composed of 9-16 battery cells connected in series. The voltage range of the battery assembly 301 is generally between 30V and 60V. In each battery module 300, the BMU serves as a collection unit and a monitoring unit of the battery assembly 301. It monitors the parameter information of the battery cell (such as voltage, temperature, power, etc.) in real time and uploads the acquired parameter information of the battery assembly 301 to the battery control unit 101.

[0043] As a specific example, the second bus 402 is a high-voltage DC bus (voltage 120V-1500V), the first bus 401 is a low-voltage DC bus (voltage 24V or 48V), the unidirectional DC transformer 201 includes a unidirectional isolated flyback DC converter, the unidirectional DC transformer 201 converts the high voltage on the second bus 402 into a voltage of 24V or 48V, and outputs it to the first bus 401, and the first bus 401 is used to supply power to the battery control unit 101, each battery management unit 303, and each first bidirectional DC converter 302.

[0044] The first bidirectional DC converter 302 is a bidirectional DC converter with relatively low power. The capacity / voltage of each battery assembly 301 is adjusted to be approximately close or consistent through the first bidirectional DC converter 302, so that each battery assembly 301 in the same battery cluster can be used in parallel. In the embodiment of the present application, the first bus and the first bidirectional DC converter are used to balance the power / capacity / voltage of each battery assembly in the battery cluster, and the voltage of the first bus (for example, 24V) is lower than that of the second bus. Therefore, the number of coil turns in the first bidirectional DC converter is smaller than that in the high-power bidirectional DC transformer in the related art, and its volume and manufacturing cost are lower, and its power consumption is also lower, which reduces the cost of the battery cluster and reduces the volume of the battery cluster.

[0045] In some embodiments of the present application, the battery control unit 101 performs parallel operation or balancing of each battery assembly based on the battery capacity of each battery assembly. In one embodiment, the battery control unit 101 is configured as follows:

[0046] In response to the capacity difference between the first battery assembly and the second battery assembly being greater than or equal to the capacity threshold, the first bidirectional DC converter of the first battery module is controlled to discharge the first battery assembly, and the first bidirectional DC converter of the second battery module is controlled to charge the second battery assembly, so that the first battery assembly transmits electric energy to the second battery assembly through the first bus 401. The first battery assembly is the battery assembly with the largest capacity among the multiple battery assemblies 301, and the second battery assembly is the battery assembly with the smallest capacity among the multiple battery assemblies 301. The first battery assembly is the battery assembly of the first battery module, and the second battery assembly is the battery assembly of the second battery module. In the above manner, the capacity of the first battery assembly and the second battery assembly is adjusted to within a predetermined range, for example, adjusted to within the range required for parallel operation, to achieve capacity balance between the first battery assembly and the second battery assembly.

[0047] The battery control unit 101 communicates with each battery management unit 303, obtains the capacity of each battery assembly 301, and sorts the capacity of each battery assembly 301, determines the first battery assembly with the largest capacity and the second battery assembly with the smallest capacity, controls the first bidirectional DC converter in the first battery module to discharge the first battery assembly, and controls the first bidirectional DC converter in the second battery module to charge the second battery assembly, so that the electric energy of the first battery assembly is transmitted to the second battery assembly through the first bus 401, until the capacity of the first battery assembly and the second battery assembly are roughly close to or meet the preset capacity condition of parallel operation. It can be understood that the capacity of each battery assembly 301 is calculated by the battery management unit 303 and transmitted to the battery control unit 101; or, the battery management unit 303 obtains the parameter information of each battery assembly 301, and transmits the parameter information to the battery control unit 101, and the battery control unit 101 calculates and determines the capacity of each battery assembly 301 based on the above parameter information.

[0048] In the present application, the capacity threshold is defined and set according to the actual situation. For example, according to the parallel conditions of the battery components and the capacity setting of the battery components, the capacity threshold is set to 1Ah, 2Ah or 5Ah, etc.

[0049] In some embodiments of the present application, when there are battery modules with a capacity value difference greater than a capacity threshold in the battery cluster, a first average value of the capacity values ​​of each battery module in the battery cluster is calculated, a battery module with the largest current capacity value is selected as the first battery module, and a battery module with the smallest current capacity value is selected as the second battery module, and the first bidirectional DC transformer connected to the first battery module, the first busbar, and the first bidirectional DC transformer connected to the second battery module are used to make the first battery module charge the second battery module until the capacity value of at least one of the first battery module and the second battery module is the first average value. The battery control unit 101 continues to determine whether there are still battery modules with a capacity value difference greater than the capacity threshold in the battery cluster. If so, return to the above steps and execute: select the battery module with the largest current capacity value to obtain the first battery module, select the battery module with the smallest current capacity value to obtain the second battery module, and control the first battery module to charge the second battery module. When the capacity value differences of each battery module are not greater than the capacity threshold, the balancing of each battery module in the battery cluster is completed.

[0050] The battery control unit 101 performs parallel operation or equalization on each battery assembly based on the voltage value of each battery assembly. In one embodiment, the battery control unit 101 is configured as follows:

[0051] In response to the voltage difference between the third battery assembly and the fourth battery assembly being greater than or equal to the voltage threshold, the first bidirectional DC converter of the third battery module is controlled to discharge the third battery assembly, and the first bidirectional DC converter of the fourth battery module is controlled to charge the fourth battery assembly, so that the third battery assembly transmits electric energy to the fourth battery assembly through the first bus 401. The third battery assembly is the battery assembly with the largest voltage among the multiple battery assemblies 301, the fourth battery assembly is the battery assembly with the smallest voltage among the multiple battery assemblies 301, the third battery assembly is the battery assembly of the third battery module, and the fourth battery assembly is the battery assembly of the fourth battery module. In the above manner, the voltage of the third battery assembly and the fourth battery assembly is adjusted to a predetermined range, for example, adjusted to a range required for parallel operation, to achieve voltage balance between the first battery assembly and the second battery assembly.

[0052] In this application, the voltage threshold is customized according to the actual situation. For example, the voltage threshold is set to 0.2V, 0.5V or 1V, etc. according to the parallel conditions of the battery components and the voltage setting of the battery components.

[0053] In some embodiments of the present application, when there are battery modules with a voltage difference greater than a voltage threshold in the battery cluster, the second average value of the voltage of each battery module in the battery cluster is calculated, the battery module with the largest current voltage value is selected to be determined as the third battery module, and the battery module with the smallest current voltage value is selected to be determined as the fourth battery module, and the first bidirectional DC transformer connected to the fourth battery module, the first transmission bus, and the first bidirectional DC transformer connected to the third battery module are used to make the third battery module charge the fourth battery module until the voltage value of at least one of the third battery module and the fourth battery module is the second average value. The battery control unit 101 continues to determine whether there are still battery modules with a voltage difference greater than the voltage threshold in the battery cluster. If so, it returns to the above steps and executes: selecting the battery module with the largest current voltage value to obtain the third battery module, and selecting the battery module with the smallest current voltage value to obtain the fourth battery module, and controlling the third battery module to charge the fourth battery module. When the voltage difference of each battery module is not greater than the voltage threshold, the balancing of each battery module in the battery cluster is completed.

[0054] The battery control unit 101 communicates with each battery management unit 303, obtains the voltage of each battery assembly 301, and sorts the voltage of each battery assembly 301, determines the third battery assembly with the highest voltage and the fourth battery assembly with the lowest voltage, controls the first bidirectional DC converter in the third battery module to discharge the third battery assembly, and controls the first bidirectional DC converter in the fourth battery module to charge the fourth battery assembly, so that the electric energy of the third battery assembly is transmitted to the fourth battery assembly through the first bus 401, until the voltage of the third battery assembly and the fourth battery assembly are roughly close to or meet the preset voltage condition of parallel operation. It is understandable that the voltage of each battery assembly 301 is collected by the battery management unit 303 and transmitted to the battery control unit 101 through communication.

[0055] In some embodiments of the present application, see Figure 3 The first bidirectional DC converter 302 is also connected to the battery control unit 101 for communication, and is configured to charge or discharge the battery assembly 301 belonging to the same battery module as itself in response to the control of the battery control unit 101.

[0056] The battery control unit 101 communicates with the first bidirectional DC converter 302 via the communication line 403 to control the first bidirectional DC converter 302 to charge and discharge the battery assembly 301 so that the battery assembly with high capacity / voltage transmits electric energy to the battery assembly with low capacity / voltage.

[0057] In some embodiments of the present application, see Figure 4 The communication between the first bidirectional DC converter 302 and the battery control unit 101 includes CAN bus (Controller Area Network) communication or daisy chain communication; and / or the communication between the battery management unit 303 and the battery control unit 101 includes CAN bus communication or daisy chain communication.

[0058] CAN bus is a serial communication protocol bus for real-time applications. It uses twisted pair to transmit signals and is a widely used communication bus. The CAN protocol provides real-time support, a transmission rate of up to 1Mb / s, and 11-bit addressing and error detection capabilities.

[0059] Daisy chain communication is a serial method for real-time applications. Daisy chain communication has a short communication distance but low cost. CAN bus transmission is stable and is used for long-distance transmission but has a high cost. In this application, the communication between the battery management unit 303 and the battery control unit 101, and the communication between the first bidirectional DC converter 302 and the battery control unit 101, are selected by those skilled in the art according to actual conditions.

[0060] The battery management unit 303 communicates with the battery control unit 101 via the first communication line 4031, and the first bidirectional DC converter 302 communicates with the battery control unit 101 via the second communication line 4032. The first communication line 4031 and the second communication line 4032 use the same or different communication methods. In one embodiment, the first communication line 4031 and the second communication line 4032 use the same communication method, see Figure 3 , the first communication line 4031 and the second communication line 4032 are the same communication line 403.

[0061] In some embodiments of the present application, see Figure 5 , further comprising: a second bidirectional DC converter 501;

[0062] A first end of the second bidirectional DC converter 501 is electrically connected to the battery assembly 301 , and a second end of the second bidirectional DC converter 501 is electrically connected to the second bus 402 .

[0063] Each battery assembly 301 in the same battery cluster is connected in series and connected to the first end of the second bidirectional DC converter 501, and the second end of the second bidirectional DC converter 501 is electrically connected to the second bus 402. In the discharge scenario, the second bidirectional DC converter 501 is used to convert the voltage of the battery assembly 301 into the voltage required by the second bus 402 to supply power to the second bus 402; in the charging scenario, the second bidirectional DC converter 501 converts the voltage of the second bus 402 into the voltage required for charging the battery assembly 301 to charge the battery assembly 301.

[0064] In some embodiments of the present application, the rated output power of the second bidirectional DC converter 501 is greater than the rated output power of the first bidirectional DC converter 302. As analyzed above, the voltage of the first bus 401 is less than the voltage of the second bus 402, and the charging and discharging power of a small voltage is generally less than the charging and discharging power of a large voltage. In one example, the rated output power of the first bidirectional DC converter 302 is: 200W~600W; and / or, the rated output power of the second bidirectional DC converter 501 is: 3000W~150KW.

[0065] The first bidirectional DC converter 302 is a DC converter with lower power compared to the second bidirectional DC converter 501. The capacity / voltage of each battery assembly 301 is balanced through the first bidirectional DC converter 302, so that each battery assembly 301 shares a high-power DC converter. Only one high-power DC converter is required in the battery cluster, thereby reducing the cost of the battery cluster.

[0066] In some embodiments of the present application, referring to FIG. 6( a ), the battery control unit 101 is configured to perform the following steps:

[0067] S1. Calculate the average capacity of multiple battery assemblies;

[0068] S2. In response to the capacity difference between the first battery assembly and the second battery assembly being greater than or equal to the capacity threshold, controlling the first bidirectional DC converter of the first battery module and the second battery module so that the first battery assembly transmits electrical energy to the second battery assembly through the first bus until the capacity of the first battery assembly or the capacity of the second battery assembly reaches an average capacity;

[0069] S3. Based on the current capacity of each battery assembly, redetermine the first battery assembly and the second battery assembly, and return to steps S1 and S2 to continue executing until the capacity difference between the battery assemblies is less than the capacity threshold.

[0070] In some embodiments of the present application, referring to FIG. 6( b ), the battery control unit 101 is configured to perform the following steps:

[0071] A1. Calculate the average voltage of each battery assembly;

[0072] A2. In response to the difference between the voltage of the third battery assembly and the voltage of the fourth battery assembly being greater than or equal to the voltage threshold, controlling the first bidirectional DC converter of the third battery module and the fourth battery module so that the third battery assembly transmits electric energy to the fourth battery assembly through the first bus until the voltage of the third battery assembly or the voltage of the fourth battery assembly reaches an average voltage;

[0073] A3. Based on the current voltage of each battery assembly, redetermine the third battery assembly and the fourth battery assembly, and return to steps A1 and A2 to continue executing until the voltage difference between the battery assemblies is less than the voltage threshold.

[0074] The battery control unit 101 controls the first bidirectional DC converter 302 to charge and discharge the battery assembly 301 so that the battery assembly with high capacity / voltage transmits power to the battery assembly with low capacity / voltage until the capacity / voltage of each battery assembly 301 is the same. For related instructions, please refer to other embodiments of the present application and will not be repeated here.

[0075] In the above embodiment, the first bidirectional DC converter and the first bus are used to achieve capacity balancing or voltage balancing of each battery assembly in the same battery cluster, so that the battery assemblies in the same battery cluster can be connected in parallel and supply power to the outside. There is no need to separately configure a high-power bidirectional DC converter for each battery assembly, thereby reducing the cost of the battery cluster.

[0076] In some embodiments of the present application, the first bus 401 is a 24V Bus line, the second bus 402 is a high-voltage DC bus, the voltage range of the high-voltage DC bus is 120V-1500V, and the unidirectional DC transformer 201 converts the high voltage voltage on the second bus 402 into a 24V voltage and outputs it to the first bus 401. The first bus 401 is used to supply power to the battery control unit 101, each battery management unit 303, and each first bidirectional DC converter 302. The first bus 401 is also used to transmit the charging and discharging of the first bidirectional DC converter 302.

[0077] In some embodiments of the present application, see Figure 7 The battery cluster further includes: a first energy storage converter 601, electrically connected to the second bus 402. The first energy storage converter 601 is a PCS (Power Conversion System), which is used for AC / DC conversion, that is, converting the DC power provided by the battery assembly into AC power for external power supply, or converting the external AC power into DC power for charging the battery assembly.

[0078] In one example, the second bidirectional DC converter is integrated in the PCS, the PCS input end is connected to the second bus 402, and the PCS output end is connected to the grid or the load.

[0079] In another example, the second bidirectional DC converter is not integrated with the first energy storage converter 601. The battery control unit 101, the battery management unit 303, the first bidirectional DC converter 302, the unidirectional DC converter 201, and the second bidirectional DC converter 501 are arranged in the electrical box of the battery cluster, and the PCS is arranged outside the electrical box.

[0080] The present application also provides an energy storage system. Figure 8 , comprising a plurality of battery clusters according to any one of the above embodiments, wherein the plurality of battery clusters are connected in parallel, the first busbars 401 of the battery clusters are electrically connected, and the battery control units 101 in the battery clusters are in communication connection.

[0081] In some embodiments of the present application, when the difference in capacity / voltage between different battery assemblies in the same battery cluster is large, the capacity / voltage of the battery assemblies 300 in the same battery cluster can be balanced through the technical solutions and principles described in the above embodiments.

[0082] In some other embodiments of the present application, when the difference in capacity / voltage between battery components in different battery clusters is large, the battery control unit 101 controls the battery components with high capacity / voltage in different battery clusters to discharge to the first bus 401, and the battery components with low capacity / voltage are charged by the first bus 401. The battery control units 101 in each battery cluster are connected to each other in communication, and the capacity / voltage of all battery components 301 in each battery cluster are sorted to determine the battery component with the highest capacity / voltage and the battery component with the lowest capacity / voltage. The battery component with the highest capacity / voltage transmits electric energy to the battery component with the lowest capacity / voltage through the first bus 401, so as to balance all battery components 301 in each battery cluster.

[0083] In some embodiments of the application, see Fig. 9 , the energy storage system also includes:

[0084] The second energy storage converter 602 is electrically connected to a plurality of battery clusters.

[0085] The detailed description of the second energy storage converter 602 refers to the first energy storage converter 601 in the embodiment of the present application, and will not be repeated here. In the embodiment of the present application, multiple battery clusters share one second energy storage converter, which further reduces the cost of the energy storage system compared to each battery cluster including one energy storage converter.

[0086] In some embodiments of the application, see Fig.10 , each battery cluster includes a first energy storage converter 601 electrically connected to the second bus 402. In the embodiment of the present application, each battery cluster includes a first energy storage converter, and each battery cluster realizes electric energy interaction with the outside world based on its own first energy storage converter. When the first energy storage converter of a single battery cluster is abnormal, it will not affect the application of other battery clusters, and the energy storage system has high availability.

[0087] In some embodiments of the present invention, the plurality of battery control units 101 are further configured as follows:

[0088] In response to the capacity difference between the fifth battery assembly and the sixth battery assembly being greater than or equal to the capacity threshold, the first bidirectional DC converter of the fifth battery module is controlled to discharge the fifth battery assembly, and the first bidirectional DC converter of the sixth battery module is controlled to charge the sixth battery assembly, so that the fifth battery assembly transmits electric energy to the sixth battery assembly through the first bus 401. The fifth battery assembly is the battery assembly with the largest capacity in the energy storage system, the sixth battery assembly is the battery assembly with the smallest capacity in the energy storage system, the fifth battery assembly is the battery assembly of the fifth battery module, and the sixth battery assembly is the battery assembly of the sixth battery module.

[0089] The battery control units 101 of each battery cluster communicate with each battery management unit 303 to obtain the capacity of each battery assembly 301. The battery control units 101 of each battery cluster communicate with each other to sort the capacity of each battery assembly 301, determine the fifth battery assembly with the largest capacity and the sixth battery assembly with the smallest capacity, control the first bidirectional DC converter of the fifth battery module to discharge the fifth battery assembly, and control the first bidirectional DC converter of the sixth battery module to charge the sixth battery assembly, so that the electric energy of the fifth battery assembly is transmitted to the sixth battery assembly through the first bus 401, until the capacity of the fifth battery assembly is roughly close to that of the sixth battery assembly or meets the preset capacity condition for parallel operation.

[0090] In some embodiments of the present invention, the plurality of battery control units 101 are further configured as follows:

[0091] In response to the voltage difference between the seventh battery assembly and the eighth battery assembly being greater than or equal to the voltage threshold, the first bidirectional DC converter of the seventh battery module is controlled to discharge the seventh battery assembly, and the first bidirectional DC converter of the eighth battery module is controlled to charge the eighth battery assembly, so that the seventh battery assembly transmits electric energy to the eighth battery assembly through the first bus 401. The seventh battery assembly is the battery assembly with the largest voltage in the energy storage system, the eighth battery assembly is the battery assembly with the smallest voltage in the energy storage system, the seventh battery assembly is the battery assembly of the seventh battery module, and the eighth battery assembly is the battery assembly of the eighth battery module.

[0092] The battery control units 101 of each battery cluster communicate with each battery management unit 303 to obtain the voltage of each battery assembly 301. The battery control units 101 of each battery cluster communicate with each other to sort the voltages of each battery assembly 301, determine the seventh battery assembly with the highest voltage and the eighth battery assembly with the lowest voltage, control the first bidirectional DC converter of the seventh battery module to discharge the seventh battery assembly, and control the first bidirectional DC converter of the eighth battery module to charge the eighth battery assembly, so that the electric energy of the seventh battery assembly is transmitted to the eighth battery assembly through the first bus 401, until the voltages of the seventh battery assembly and the eighth battery assembly are roughly close to or meet the preset voltage condition for parallel operation.

[0093] In the above-mentioned embodiment of the present application, the battery assembly is used as the basic unit to achieve capacity / d voltage balancing of the battery assemblies between different battery clusters. Compared with balancing of the battery cluster assemblies using the battery cluster as the basic unit, there is no need to balance the battery assemblies in each battery cluster first, thereby reducing the power loss caused by balancing in the battery cluster and improving the energy utilization of the battery system.

[0094] In some embodiments of the present invention, the plurality of battery control units 101 are configured as follows:

[0095] In response to the capacity difference between the first battery cluster and the second battery cluster being greater than or equal to the capacity threshold, the first bidirectional DC converter 302 of the first battery cluster is controlled to discharge the first battery cluster, and the first bidirectional DC converter 302 of the second battery cluster is controlled to charge the second battery cluster, so that the first battery cluster transmits electric energy to the second battery cluster through the first bus 401. The first battery cluster is the battery cluster with the largest capacity among the multiple battery clusters, and the second battery cluster is the battery cluster with the smallest capacity among the multiple battery clusters.

[0096] With reference to other embodiments of the present application, after the capacity / voltage balancing of the battery components 301 in the same battery cluster is completed, the battery control units 101 of each battery cluster communicate, sort the capacity of each battery cluster, determine the first battery cluster with the highest capacity and the second battery cluster with the lowest capacity, and the battery control unit 101 of the first battery cluster controls the discharge of the first battery cluster, and the battery control unit 101 of the second battery cluster controls the charging of the second battery cluster, so that the first battery cluster transmits electric energy to the second battery cluster through the first bus 401 until the capacities of the first battery cluster and the second battery cluster are roughly close to or meet the preset capacity conditions for parallel operation.

[0097] In an embodiment of the present application, battery components within the same battery cluster are balanced first, and the balancing of battery components within each battery cluster is performed in parallel. Then, balancing between different battery clusters is achieved using the battery cluster as the basic unit. Compared with balancing using the battery component as the basic unit, the balancing between battery clusters is more efficient.

[0098] In some embodiments of the present invention, the plurality of battery control units 101 are configured as follows:

[0099] In response to the voltage difference between the third battery cluster and the fourth battery cluster being greater than or equal to the voltage threshold, the first bidirectional DC converter 302 of the third battery cluster is controlled to discharge the third battery cluster, and the first bidirectional DC converter 302 of the fourth battery cluster is controlled to charge the fourth battery cluster, so that the third battery cluster transmits electric energy to the fourth battery cluster through the first bus 401. The third battery cluster is the battery cluster with the largest voltage among the multiple battery clusters, and the fourth battery cluster is the battery cluster with the smallest voltage among the multiple battery assemblies.

[0100] With reference to other embodiments of the present application, after the battery components in the same battery cluster are balanced, the battery control units 101 of each battery cluster communicate, sort the voltages of each battery cluster, determine the third battery cluster with the highest voltage and the fourth battery cluster with the lowest voltage, and the battery control unit 101 of the third battery cluster controls the discharge of the third battery cluster, and the battery control unit 101 of the fourth battery cluster controls the charging of the fourth battery cluster, so that the third battery cluster transmits electric energy to the fourth battery cluster through the first bus 401 until the voltages of the third battery cluster and the fourth battery cluster are roughly close to or meet the preset voltage condition for parallel operation.

[0101] In the above embodiment, the battery components in the same battery cluster are balanced first, and the balancing of the battery components in each battery cluster is performed in parallel. Then, the capacity / voltage balancing between different battery clusters is achieved using the battery cluster as the basic unit. Compared with balancing using the battery component as the basic unit, the balancing efficiency between battery clusters is higher.

[0102] Figure 8-Figure 10 Only two battery clusters are connected in parallel as an example, and the implementation process of other number of battery clusters connected in parallel is similar to the implementation process of two battery clusters connected in parallel, which will not be described in detail in this application.

[0103] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0104] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of other embodiments.

[0105] The above are only preferred embodiments of the present application and are not intended to limit the protection scope of the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application are included in the protection scope of the present application.

Claims

1. A battery cluster, characterized in that: include: Battery control unit, unidirectional DC transformer and multiple battery modules; The output end of the unidirectional DC transformer is electrically connected to the first bus, and the input end of the unidirectional DC transformer is electrically connected to the second bus; wherein the operating voltage of the second bus is higher than the operating voltage of the first bus; A plurality of the battery modules are connected in series and electrically connected to the second bus bar, and each of the battery modules comprises: a battery assembly, a first bidirectional DC converter and a battery management unit; In each of the battery modules: the first bidirectional DC converter is electrically connected to the first bus and the battery assembly respectively, the battery management unit is electrically connected to the battery assembly and the first bus respectively, and the battery management unit is also communicatively connected to the battery control unit.

2. The battery cluster according to claim 1, characterized in that: The battery control unit is configured as follows: In response to a capacity difference between the first battery assembly and the second battery assembly being greater than or equal to a capacity threshold, controlling the first bidirectional DC converter of the first battery module to discharge the first battery assembly, and controlling the first bidirectional DC converter of the second battery module to charge the second battery assembly, so that the first battery assembly transmits electric energy to the second battery assembly through the first bus; Wherein, the first battery assembly is the battery assembly with the largest capacity among the plurality of battery assemblies, the second battery assembly is the battery assembly with the smallest capacity among the plurality of battery assemblies, the first battery assembly is the battery assembly of the first battery module, and the second battery assembly is the battery assembly of the second battery module; and / or, In response to a voltage difference between the third battery assembly and the fourth battery assembly being greater than or equal to a voltage threshold, controlling the first bidirectional DC converter of the third battery module to discharge the third battery assembly, and controlling the first bidirectional DC converter of the fourth battery module to charge the fourth battery assembly, so that the third battery assembly transmits electric energy to the fourth battery assembly through the first busbar; Among them, the third battery assembly is the battery assembly with the largest voltage among the multiple battery assemblies, the fourth battery assembly is the battery assembly with the smallest voltage among the multiple battery assemblies, the third battery assembly is the battery assembly of the third battery module, and the fourth battery assembly is the battery assembly of the fourth battery module.

3. The battery cluster according to claim 1 or 2, characterized in that: The first bidirectional DC converter is also connected to the battery control unit for communication, and is configured to charge or discharge the battery components belonging to the same battery module as the first bidirectional DC converter in response to the control of the battery control unit.

4. The battery cluster according to claim 3, characterized in that: The communication between the first bidirectional DC converter and the battery control unit includes CAN bus communication or daisy chain communication; and / or, The communication between the battery management unit and the battery control unit includes CAN bus communication or daisy chain communication.

5. The battery cluster according to any one of claims 1 to 4, characterized in that: Also includes: a second bidirectional DC converter; A first end of the second bidirectional DC converter is electrically connected to the battery assembly, and a second end of the second bidirectional DC converter is electrically connected to the second busbar.

6. The battery cluster according to claim 5, characterized in that: The rated output power of the second bidirectional DC converter is greater than the rated output power of the first bidirectional DC converter.

7. The battery cluster according to claim 6, characterized in that: The rated output power of the first bidirectional DC converter is: 200W~600W; and / or, The rated output power of the second bidirectional DC converter is: 3000W~150KW.

8. The battery cluster according to any one of claims 2 to 7, characterized in that: The battery control unit is configured to perform the following steps: S1. Calculate the average capacity of the plurality of battery assemblies; S2. In response to the capacity difference between the first battery assembly and the second battery assembly being greater than or equal to a capacity threshold, controlling the first bidirectional DC converter of the first battery module and the second battery module so that the first battery assembly transmits electric energy to the second battery assembly through the first bus bar until the capacity of the first battery assembly or the capacity of the second battery assembly reaches the average capacity; S3. Based on the current capacity of each of the battery assemblies, the first battery assembly and the second battery assembly are re-determined, and steps S1 and S2 are returned to continue until the capacity difference between the battery assemblies is less than the capacity threshold; and / or, A1. Calculate the average voltage of each of the battery assemblies; A2. In response to the difference between the voltage of the third battery assembly and the voltage of the fourth battery assembly being greater than or equal to the voltage threshold, controlling the first bidirectional DC converter of the third battery module and the fourth battery module so that the third battery assembly transmits electric energy to the fourth battery assembly through the first bus until the voltage of the third battery assembly or the voltage of the fourth battery assembly reaches the average voltage; A3. Based on the current voltage of each of the battery assemblies, redetermine the third battery assembly and the fourth battery assembly, and return to steps A1 and A2 to continue executing until the voltage difference between each of the battery assemblies is less than the voltage threshold.

9. The battery cluster according to any one of claims 1 to 8, characterized in that: The first bus is a 24V Bus line, and the second bus is a DC bus.

10. The battery cluster according to any one of claims 1 to 9, characterized in that: include: The first energy storage converter is electrically connected to the second bus.

11. An energy storage system, characterized in that: comprising a plurality of battery clusters as claimed in any one of claims 1 to 9, wherein the plurality of battery clusters are connected in parallel; The first busbars of the battery clusters are electrically connected, and the battery control units in the battery clusters are communicatively connected.

12. The energy storage system according to claim 11, characterized in that: include: The second energy storage converter is electrically connected to the plurality of battery clusters.

13. The energy storage system according to claim 11, characterized in that: Each of the battery clusters includes a first energy storage converter electrically connected to the second bus bar.

14. The energy storage system according to any one of claims 11 to 13, characterized in that: The plurality of battery control units are further configured as: In response to the capacity difference between the fifth battery assembly and the sixth battery assembly being greater than or equal to the capacity threshold, controlling the first bidirectional DC converter of the fifth battery module to discharge the fifth battery assembly, and controlling the first bidirectional DC converter of the sixth battery module to charge the sixth battery assembly, so that the fifth battery assembly transmits electric energy to the sixth battery assembly through the first bus; Wherein, the fifth battery assembly is the battery assembly with the largest capacity in the energy storage system, the sixth battery assembly is the battery assembly with the smallest capacity in the energy storage system, the fifth battery assembly is the battery assembly of the fifth battery module, and the sixth battery assembly is the battery assembly of the sixth battery module; and / or, In response to the voltage difference between the seventh battery assembly and the eighth battery assembly being greater than or equal to the capacity threshold, controlling the first bidirectional DC converter of the seventh battery module to discharge the seventh battery assembly, and controlling the first bidirectional DC converter of the eighth battery module to charge the eighth battery assembly, so that the seventh battery assembly transmits electric energy to the eighth battery assembly through the first bus; Among them, the seventh battery assembly is the battery assembly with the largest voltage in the energy storage system, the eighth battery assembly is the battery assembly with the smallest voltage in the energy storage system, the seventh battery assembly is the battery assembly of the seventh battery module, and the eighth battery assembly is the battery assembly of the eighth battery module.

15. The energy storage system according to any one of claims 11 to 13, characterized in that: The plurality of battery control units are configured as follows: In response to a capacity difference between the first battery cluster and the second battery cluster being greater than or equal to a capacity threshold, controlling the first bidirectional DC converter of the first battery cluster to discharge the first battery cluster, and controlling the first bidirectional DC converter of the second battery cluster to charge the second battery cluster, so that the first battery cluster transmits electric energy to the second battery cluster through the first bus; Wherein, the first battery cluster is a battery cluster with the largest capacity among the plurality of battery clusters, and the second battery cluster is a battery cluster with the smallest capacity among the plurality of battery clusters; and / or, In response to a voltage difference between the third battery cluster and the fourth battery cluster being greater than or equal to a voltage threshold, controlling the first bidirectional DC converter of the third battery cluster to discharge the third battery cluster, and controlling the first bidirectional DC converter of the fourth battery cluster to charge the fourth battery cluster, so that the third battery cluster transmits electric energy to the fourth battery cluster through the first bus; The third battery cluster is a battery cluster with the largest voltage among the multiple battery clusters, and the fourth battery cluster is a battery cluster with the smallest voltage among the multiple battery assemblies.

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