Energy storage system control circuit and energy storage control method

Abstract

The invention discloses an energy storage system control circuit, and relates to the technical field of energy storage systems. The invention discloses an energy storage system control circuit which mainly comprises an energy storage battery module, an electric energy control module and a power supply module. Each module in the battery pack is connected with an equalization circuit in parallel, one end of a direct current-to-alternating current circuit in the electric energy control module is connected with the output end of the battery pack, and the other end of the direct current-to-alternating current circuit in the electric energy control module is connected with each module in the battery pack and the equalization circuit through a rectification filter circuit to form an electrical loop. Meanwhile, direct current of the battery pack is converted into alternating current to serve as a standby power supply through direct current to alternating current, alternating current of mains supply and alternating current converted by the battery pack serve as input of a switching power supply through automatic transfer switching equipment, flexible switching of the power supply is achieved, and stability and reliability of the energy storage system are improved.

Description

Technical Field

[0001] The present application relates to the technical field of energy storage systems, and in particular to an energy storage system control circuit and an energy storage control method. Background Art

[0002] With the growing global demand for renewable energy, energy storage technology has received widespread attention as an important means to achieve sustainable energy development. Among them, energy storage batteries are widely used in power systems, new energy power generation and other fields due to their high efficiency, environmental protection and safety. However, during the use of energy storage batteries, due to various reasons (such as aging, changes in ambient temperature, number of charge and discharge cycles, etc.), they may experience problems such as capacity decay and increased internal resistance, which will affect their performance and service life. Therefore, how to effectively manage and maintain energy storage batteries to ensure their stable and efficient operation is an urgent problem to be solved in the current field of energy storage technology. The solution of the existing technology is mainly to monitor and manage energy storage batteries through a battery management system (BMS), and to achieve effective management of batteries by real-time monitoring of battery parameters such as voltage, current, temperature, as well as battery health status (SOH), remaining capacity (SOC) and other information.

[0003] Existing technical solutions still have some problems and shortcomings in practical applications. First, although existing BMS systems can monitor battery status in real time, there are often errors in estimating the health status and remaining capacity of each module. This can lead to inconsistencies between module voltages and SOC, thus affecting battery life. Second, there are often errors in the voltages between battery packs, resulting in inconsistencies between the voltage and SOC of the battery packs, which can also affect the life of the entire energy storage system. Summary of the Invention

[0004] In order to overcome the shortcomings of the existing technology, this application proposes an energy storage system control circuit and an energy storage control method, which realizes voltage balancing of battery packs and modules in the energy storage system by configuring a corresponding balancing management circuit structure and balancing management strategy in the energy storage system.

[0005] In a first aspect, the present application provides an energy storage system control circuit, comprising: an energy storage battery module, an electric energy control module, and a power supply module;

[0006] The energy storage battery module includes at least one battery pack, each module inside the battery pack is connected in parallel with a balancing circuit; the battery pack is also equipped with an MCU and a rectifier and filter circuit;

[0007] The power control module includes a DC-to-AC circuit and a controller. The input end of the DC-to-AC circuit is connected to the output end of the battery pack. The output end of the DC-to-AC circuit is connected to each module and the balancing circuit inside the battery pack via the rectifier and filter circuit. The controller is connected to the MCU of the battery pack.

[0008] The power supply module includes an automatic transfer switch and a switching power supply. The first input end of the automatic transfer switch is connected to the output end of the DC to AC circuit, the second input end of the automatic transfer switch is connected to the mains, the output end of the automatic transfer switch is connected to the input end of the switching power supply, and the output end of the switching power supply is connected to the controller in the power controller module and the MCU inside the battery pack.

[0009] Furthermore, when the energy storage battery module includes multiple battery packs, each battery pack is connected to a charging control circuit, the charging control circuit includes a switching circuit and a balancing circuit, the output negative pole of the battery pack is connected in parallel with one of the balancing circuits, the output positive pole of the battery pack is connected to the switching circuit, and the switching circuit is connected in parallel with one of the balancing circuits.

[0010] Preferably, the switch circuit adopts a circuit formed by connecting a fuse and a relay in series.

[0011] The balancing circuit adopts a circuit formed by connecting a current limiting resistor and a relay in series.

[0012] The DC to AC circuit adopts an H-bridge circuit.

[0013] The power control module adopts a high-voltage distribution box, which includes a current input interface, a current output interface, an AC output interface, a DC input interface and a communication signal interface;

[0014] The input end of the DC-to-AC circuit is connected to the output positive pole and output negative pole of the battery pack via the current input interface, and the output end of the DC-to-AC circuit is connected to the input end of the rectifier and filter circuit and the automatic transfer switch electrical appliance via the AC output interface; the controller is connected to the MCU of the battery pack via the communication signal interface, and the controller is connected to the output end of the switching power supply via the DC input interface.

[0015] Preferably, a fuse and a circuit breaker are provided between the current input interface and the current output interface of the high-voltage distribution box.

[0016] In a second aspect, the present application provides an energy storage control method applied to the above-mentioned energy storage system control circuit, the method comprising:

[0017] The controller in the energy storage system control circuit obtains the voltage of each module inside the battery pack;

[0018] The controller determines whether the voltage difference between each module meets the first preset voltage difference range. If so, there is no need to perform voltage balancing control on each module. Otherwise, each module is charged by controlling the balancing circuit connected in parallel to each module until the voltage difference between each module is less than the preset voltage value.

[0019] In a third aspect, the present application provides an energy storage control method applied to the above-mentioned energy storage system control circuit, the method comprising:

[0020] The controller in the energy storage system control circuit obtains the voltage of each battery pack and the voltage of each module inside the battery pack;

[0021] The controller determines whether the voltage difference between each module meets the first preset voltage difference range and determines whether the voltage difference between each battery pack meets the second preset voltage difference range;

[0022] When it is determined that the voltage difference between the modules does not meet the first preset voltage difference range, the controller controls the balancing circuit connected in parallel to the modules to charge the modules until the voltage difference between the modules is less than the preset voltage value;

[0023] When it is determined that the voltage difference between each battery pack does not meet the second preset voltage difference range, the controller charges each battery pack by controlling the charging control circuit connected to each battery pack until the voltage difference between each battery pack is less than the preset voltage value.

[0024] Preferably, the first preset voltage difference range is greater than 1V and less than 3V, the second preset voltage difference range is greater than 5V, and the preset voltage value is 1V.

[0025] The above one or more technical solutions of this application have at least one or more of the following beneficial effects:

[0026] In the technical solution for implementing the present application, the present invention configures a balancing circuit between the modules inside the battery pack, connects the input end of the DC-to-AC circuit to the output end of the battery pack, and connects the output end of the DC-to-AC circuit to the modules inside the battery pack and the balancing circuit via a rectifier and filter circuit to form an electrical circuit. Based on the electrical circuit, voltage balancing between modules is achieved, overcharging or over-discharging of some modules is avoided, and the service life of the battery is improved; voltage balancing between battery packs is achieved, performance differences between battery packs are avoided, and the efficiency and life of the energy storage system are improved. The switching power supply in the present invention simultaneously utilizes two AC lines to provide 24V DC power, realizing a dual-input switching power supply, meeting the demand for an uninterruptible power supply, and improving the reliability of the system. The energy storage control method based on the energy storage system control circuit of the present application can be used to monitor and simultaneously control the operation of the entire energy storage system, realizing intelligent management and control of energy storage batteries, and improving the service life and efficiency of batteries. Furthermore, the present invention converts the DC power of the battery pack into AC power as a backup power supply by utilizing a DC-to-AC converter, and simultaneously utilizes an automatic switching switch to use the AC power from the mains and the AC power converted from the battery pack as the input of the switching power supply, thereby achieving flexible switching of power supplies and improving the stability and reliability of the energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The disclosure of this application will be more easily understood with reference to the accompanying drawings. Those skilled in the art will readily appreciate that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. Furthermore, similar numbers in the figures represent similar components, where:

[0028] Figure 1 1 is a schematic diagram of the structure of an energy storage system control circuit provided in accordance with Example 1 of the present application;

[0029] Figure 2 yes Figure 1 Schematic diagram of the internal structure of the battery pack shown in;

[0030] Figure 3 yes Figure 2 Schematic diagram of the composition and connection relationship of the module and the equalization circuit shown in;

[0031] Figure 4 yes Figure 1 Schematic diagram of the composition and connection relationship of the battery pack and the charging control circuit shown in;

[0032] Figure 5 This is a schematic diagram of a specific implementation structure of an energy storage system control circuit applied to four battery packs provided in Example 2 of the present application;

[0033] Figure 6 yes Figure 5Schematic diagram of the connection relationship between any two battery packs in the circuit shown.

[0034] Figure 7 This is a flowchart of a method for implementing voltage balancing control between modules according to Example 3 of the present application;

[0035] Figure 8 This is a flowchart of a method for implementing voltage balancing control between battery packs provided in Example 3 of the present application. DETAILED DESCRIPTION

[0036] Some embodiments of the present application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present application and are not intended to limit the scope of protection of the present application.

[0037] In the description of this application, "module" and "processor" may include hardware, software, or a combination of both. A module may include hardware circuitry, various suitable sensors, communication ports, and memory. It may also include software components, such as program code, or a combination of software and hardware. A processor may be a central processing unit, a microprocessor, an image processor, a digital signal processor, or any other suitable processor. A processor has data and / or signal processing capabilities. A processor may be implemented in software, hardware, or a combination of both. Non-transitory computer-readable storage media include any suitable medium capable of storing program code, such as magnetic disks, hard disks, optical disks, flash memory, read-only memory, random access memory, etc. The term "A and / or B" refers to all possible combinations of A and B, such as only A, only B, or both A and B. The terms "at least one of A or B" or "at least one of A and B" have similar meanings to "A and / or B" and may include only A, only B, or both A and B. The singular forms "one" and "the" may also include the plural forms.

[0038] Example 1

[0039] See attached Figure 1 The embodiment of the present application provides an energy storage system control circuit, which can not only solve the voltage balancing problem between modules and prevent some modules from being overcharged or over-discharged, thereby improving the service life of the battery; it can also solve the voltage balancing problem between battery packs connected in series, eliminate the performance differences between battery packs, and improve the stability and efficiency of the energy storage system; in addition, the designed power supply circuit provides a dual-input switching power supply, which can meet the needs of uninterruptible power supply. Figure 1 The energy storage system control circuit shown in the figure, wherein the energy storage battery module can be understood as an energy storage system including a battery pack, the energy storage control circuit of this embodiment includes an energy storage battery module 10, a power control module 20 and a power supply module 30.

[0040] The energy storage battery module 10 includes at least one battery pack 11. Figure 1 As shown, the energy storage battery module includes battery pack 1, battery pack 2, ..., battery pack n, where n is an integer greater than or equal to 1. Each battery pack contains multiple modules, and each module contains multiple battery cells. These battery cells can be lithium-ion batteries, nickel-metal hydride batteries, etc. The specific type is selected according to actual needs. Figure 2 As shown, the internal structure of the battery pack 11 in the energy storage system control circuit is as follows: the battery pack 11 contains multiple modules, such as module 1, module 2, ... module m, where m is an integer greater than or equal to 2; each battery pack is also configured with an MCU (micro control unit) 110 and a rectifier filter circuit 112, and each module in the battery pack is connected in parallel with a balancing circuit, the rectifier filter circuit 112 is connected to the module via the balancing circuit, and the MCU 110 is connected to each module. Furthermore, the composition and connection relationship 111 of each module in the battery pack and its parallel balancing circuit are as follows. Figure 3 As shown, the balancing circuit 40 uses a current limiting resistor R connected in series with a relay K, the current limiting resistor is connected to the positive output of the module, and the relay is connected to the negative output of the module. Further, when the energy storage battery module includes multiple battery packs, as shown in FIG. Figure 4 As shown, the composition and connection relationship of each battery pack 11 and the charging control circuit 12 in the energy storage system control circuit are as follows: the charging control circuit 12 includes a balancing circuit 40 and a switching circuit 50. The output negative electrode of the battery pack 11 is connected in parallel with the balancing circuit 40, and the output positive electrode of the battery pack 11 is connected to the switching circuit 50. The switching circuit 50 is connected in parallel with the balancing circuit 40. The balancing circuit 40 uses a current-limiting resistor R in series with a relay K, and the switching circuit 50 uses a fuse FU in series with a relay.

[0041] The power control module 20 includes a DC to AC circuit and a controller. The input end of the DC to AC circuit is connected to the output end of the battery pack in the energy storage battery module. It can be understood that the output end of the battery pack includes an output positive electrode and an output negative electrode. When the energy storage battery module includes one battery pack, the output end of the battery pack is specifically as follows: Figure 3 The output positive electrode and output negative electrode are formed by connecting the modules in parallel with the balancing circuit; when the energy storage battery module includes multiple battery packs, the output end of the battery pack is specifically as follows Figure 4The battery packs shown are connected to the charging control circuit to form a positive output electrode and a negative output electrode. The output end of the DC-to-AC circuit is connected to the modules and the balancing circuit within the battery pack via the rectifier and filter circuit within the battery pack. In the loop formed by the DC-to-AC circuit, the DC-to-AC circuit can convert the DC power from the battery pack into AC power and output the DC power through the rectifier and filter circuit to supply the modules within the battery pack. The controller is connected to the MCU within the battery pack. In this embodiment, the MCU can be used to control the modules and measure voltages. The MCU obtains the voltages of the pre-set voltage measurement points in the circuit, allowing the MCU to obtain the voltages of the modules and the battery packs in real time. The controller provided in the embodiment of the present application is connected to the MCU. The MCU can obtain the voltages of the modules within the battery pack and control the balancing circuit based on the voltages of the modules to achieve voltage balancing between the modules. The controller can also obtain the voltages of the battery packs through the MCU and control the charging control circuit based on the voltages of the battery packs to achieve voltage balancing between the battery packs. In practical applications, the power control module can be specifically a high-voltage distribution box, and the DC-to-AC circuit can preferably adopt an H-bridge circuit. The high-voltage distribution box includes a current input interface, a current output interface, an AC output interface, a DC input interface, and a communication signal interface. The input end of the DC-to-AC circuit is connected to the positive output and negative output of the battery pack via the current input interface, and the output end of the DC-to-AC circuit is connected to the input end of the rectifier filter circuit and the automatic transfer switch via the AC output interface. The controller is connected to the MCU of the battery pack via the communication signal interface, and the controller is connected to the output end of the switching power supply via the DC input interface. Furthermore, a current sensor, a circuit breaker, and a fuse can be provided between the current input interface and the current output interface of the high-voltage distribution box. The current sensor can be used to measure the magnitude and direction of the charging and discharging current, the fuse can be used to provide short-circuit protection for the energy storage battery module, and the circuit breaker can be used to provide overload protection and short-circuit protection for the energy storage battery module.

[0042] In which, the power supply module 30 includes an automatic transfer switch (ATS) and a switching power supply. The first input end of the automatic transfer switch is connected to the output end of the DC to AC circuit, the second input end of the automatic transfer switch is connected to the mains, and the output end of the automatic transfer switch is connected to the input end of the switching power supply. The switching power supply is responsible for converting AC power into 24V DC power. The output end of the switching power supply is connected to the controller in the power controller module and the MCU inside the battery pack. It can be seen that in the embodiment of the present application, the ATS can realize a seamless switching loop of dual AC branch power supplies, thereby realizing that the switching power supply in the power supply module 30 provides uninterrupted power supply to the energy storage battery module.

[0043] Example 2

[0044] Based on the energy storage system control circuit of Example 1, Figure 5 and Figure 6 As shown, this embodiment provides a specific implementation structure of an energy storage system control circuit including four battery packs.

[0045] like Figure 5 As shown, each battery pack 1 (PACK1), battery pack 2 (PACK2), battery pack 3 (PACK3), and battery pack 4 (PACK4) is equipped with an internal MCU. Each battery pack's MCU is connected to the controller in the high-voltage box via the CAN bus. A Hall effect current sensor HL1 is provided in the high-voltage box to measure the magnitude and direction of the charging and discharging current. A current relay KA1 controls the opening and closing of the loop formed by the H-bridge circuit and the battery pack. A fuse FU1 is provided for short-circuit protection of the battery cluster, and a circuit breaker QF2 is provided for overload and short-circuit protection of the battery cluster. The high-voltage box is equipped with an H-bridge circuit and relay K31. Relay K31 controls the H-bridge circuit, which is connected to the automatic transmission system (ATS), which is in turn connected to a switching power supply. The H-bridge circuit converts the battery's DC power into AC power and outputs it to the ATS. The ATS is an automatic transfer switch that automatically switches between two power sources to ensure a continuous power supply. In this embodiment, the ATS can achieve seamless switching between dual AC branch power sources. The switching power supply converts the AC power into 24V DC power for the controller.

[0046] Figure 5The example in the figure shows that each PACK contains four modules, each of which is connected in parallel to a balancing circuit. Each module in each PACK and the balancing circuit connected in parallel to each module are connected to a rectifier device. Each rectifier device is connected to the output of the H-bridge circuit in the high-voltage box via a switch K14. By controlling the opening and closing of switch K14, the charging of each battery pack can be individually controlled. The H-bridge circuit is a power electronic circuit composed of four power electronic switching devices (such as MOSFETs and IGBTs). By controlling the conduction and shutdown of these four switching devices, it can convert direct current into alternating current.

[0047] The following combination Figure 6 right Figure 5 The connection relationship between the battery packs shown in FIG is explained, and it can be understood that Figure 6 Taking PACK1 and PACK2 as examples, the internal components and connection relationships of the two battery packs are shown. Figure 6 As shown, relays and resistors are connected in parallel between the modules in PACK1 and PACK2 as the balancing circuit between the modules. For example, R1 to R4 and K1 to K4 in PACK1 and PACK2 control the charging and discharging of modules 1 to 4 respectively. That is, the controller controls the balancing circuits connected in parallel with each module to charge different modules separately. Figure 6 The rectifier filter circuit composed of transformer U1, rectifier VD1, capacitor C1, resistor R1 and diode shown in FIG corresponds to Figure 5 The rectifier shown in FIG is used to provide direct current to the module. Figure 6 The balancing circuits formed by the circuit breaker K12, resistor R12, circuit breaker K13, resistor R13, and circuit breaker K22, resistor R22, circuit breaker K23, and resistor R23 shown in the figure are respectively used as bypass control for PACK1 and PACK2 to achieve voltage balancing between PACK1 and PACK2. The switching circuits formed by the fuse FU11, circuit breaker K11, and fuse FU21 and circuit breaker K21 are respectively used as short-circuit protection and loop control for the positive circuit loops of PACK1 and PACK2. By controlling the balancing circuits and switching circuits connected to each battery pack through the controller, each battery pack can be charged to achieve voltage balancing.

[0048] Example 3

[0049] An energy storage control method provided in an embodiment of the present application can be applied to the energy storage system control circuit of embodiments 1 and 2, and utilizes the following electrical circuit formed in the energy storage system control circuit: the input end of the DC-to-AC circuit is connected to the output end of the battery pack, and the output end of the DC-to-AC circuit is connected to the various modules and the balancing circuit inside the battery pack through the rectifier and filter circuit in the battery pack, which can realize the conversion of DC power from the battery pack into AC power, and output DC power through the rectifier and filter circuit to supply the various modules in the battery pack for charging to achieve voltage balancing control. Its application scenario is: when the battery pack or module completes charging and discharging and is in the static standby stage, the controller measures and obtains the voltage of the battery pack and the voltage of the module in real time through the voltage detection circuit, and triggers the execution of the energy storage control method provided in the embodiment of the present application by calculating the voltage difference between the battery packs or modules and judging that voltage balancing control is required based on the voltage difference.

[0050] In a specific implementation, when the energy storage system control circuit includes only one battery pack, an energy storage control method provided in an embodiment of the present application includes the following steps:

[0051] Step 101: A controller in the energy storage system control circuit obtains the voltage of each module in the battery pack;

[0052] Step 102: The controller determines whether the voltage difference between the modules meets the first preset voltage difference range. If so, there is no need to perform voltage balancing control on the modules. Otherwise, the controller controls the balancing circuits connected in parallel to the modules to charge the modules until the voltage difference between the modules is less than the preset voltage value.

[0053] For example, the four modules contained in the battery pack are each connected in parallel with a balancing circuit consisting of a resistor R1 and a relay K1 in series. When the controller detects based on the voltage detection circuit that the voltage difference between any two of the four modules exceeds the first preset voltage difference range, the controller sequentially turns on the relay switches corresponding to the modules to charge the three modules with lower voltage values ​​in sequence. When the voltage differences between the three modules and the module with the highest voltage value are all less than the preset voltage value, the relay switches of the corresponding modules are turned off. For details, please refer to Figure 7 The process shown.

[0054] In a specific embodiment, when the energy storage system control circuit includes multiple battery packs, an energy storage control method provided in an embodiment of the present application includes the following steps:

[0055] Step 202: The controller in the energy storage system control circuit obtains the voltage of each battery pack and the voltage of each module inside the battery pack;

[0056] Step 202: The controller determines whether the voltage difference between each module meets the first preset voltage difference range and determines whether the voltage difference between each battery pack meets the second preset voltage difference range;

[0057] When it is determined that the voltage difference between each module does not meet the first preset voltage difference range, the controller is triggered to perform module voltage balancing control, that is, the controller controls the balancing circuit connected in parallel to each module to charge each module until the voltage difference between each module is less than the preset voltage value.

[0058] When it is determined that the voltage difference between each battery pack does not meet the second preset voltage difference range, the controller is triggered to perform battery pack voltage balancing control, that is, the controller charges each battery pack by controlling the charging control circuit connected to each battery pack until the voltage difference between each battery pack is less than the preset voltage value.

[0059] For example, the energy storage system control circuit includes Figure 6 The two battery packs shown are PACK1 and PACK2. The charging control circuit connected to PACK1 includes: a balancing circuit formed by relay K12, resistor R12, relay K13, and resistor R13, and a switching circuit formed by fuse FU11 and relay K11; the charging control circuit connected to PACK2 includes: a balancing circuit formed by relay K22, resistor R22, relay K23, and resistor R23, and a switching circuit formed by fuse FU21 and relay K21. When the controller detects that the voltage difference between PACK1 and PACK2 does not meet the second preset voltage difference range, it realizes balanced control of the voltage of each battery pack by disconnecting all relay switches in the switching circuit and closing all relay switches in the balancing circuit until the voltage difference between each battery pack is less than the preset voltage value, disconnecting all relay switches in the balancing circuit and closing all relay switches in the switching circuit. For details, please refer to Figure 8 The process shown.

[0060] Furthermore, in this embodiment, the first preset voltage difference range is greater than 1V and less than 3V, the second preset voltage difference range is greater than 5V, and the preset voltage value is 1V.

[0061] Thus far, the technical solutions of the present application have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is readily understood by those skilled in the art that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present application.

Claims

1. An energy storage system control circuit, characterized in that: include: Energy storage battery module, power control module and power supply module; The energy storage battery module includes at least one battery pack, each module inside the battery pack is connected in parallel with a balancing circuit; the battery pack is also configured with an MCU and a rectifier filter circuit; The power control module includes a DC-to-AC circuit and a controller, the input end of the DC-to-AC circuit is connected to the output end of the battery pack, the output end of the DC-to-AC circuit is connected to each module and a balancing circuit inside the battery pack via the rectifier and filter circuit, and the controller is connected to the MCU of the battery pack; The power supply module includes an automatic transfer switch and a switching power supply. The first input end of the automatic transfer switch is connected to the output end of the DC to AC circuit, the second input end of the automatic transfer switch is connected to the AC power supply, the output end of the automatic transfer switch is connected to the input end of the switching power supply, and the output end of the switching power supply is connected to the controller in the power controller module and the MCU inside the battery pack.

2. The energy storage system control circuit according to claim 1, characterized in that: When the energy storage battery module includes multiple battery packs, each battery pack is connected to a charging control circuit, the charging control circuit includes a switching circuit and a balancing circuit, the output negative electrode of the battery pack is connected in parallel with one of the balancing circuits, the output positive electrode of the battery pack is connected to the switching circuit, and the switching circuit is connected in parallel with one of the balancing circuits.

3. The energy storage system control circuit according to claim 2, characterized in that: The switch circuit adopts a circuit formed by connecting a fuse and a relay in series.

4. The energy storage system control circuit according to claim 1 or 2, characterized in that: The balancing circuit adopts a circuit formed by connecting a current limiting resistor and a relay in series.

5. The energy storage system control circuit according to claim 1 or 2, characterized in that: The DC to AC circuit adopts an H-bridge circuit.

6. The energy storage system control circuit according to claim 1 or 2, characterized in that: The power control module adopts a high-voltage distribution box, which includes a current input interface, a current output interface, an AC output interface, a DC input interface and a communication signal interface; The input end of the DC-to-AC circuit is connected to the output positive pole and the output negative pole of the battery pack via the current input interface, and the output end of the DC-to-AC circuit is connected to the input end of the rectifier and filter circuit and the automatic transfer switch electrical appliance via the AC output interface; the controller is connected to the MCU of the battery pack via the communication signal interface, and the controller is connected to the output end of the switching power supply via the DC input interface.

7. The energy storage system control circuit according to claim 6, characterized in that: A fuse and a circuit breaker are arranged between the current input interface and the current output interface of the high-voltage distribution box.

8. A method for controlling energy storage, characterized in that: Applied to the energy storage system control circuit according to any one of claims 1 to 7, the method comprises: The controller in the energy storage system control circuit obtains the voltage of each module inside the battery pack; The controller determines whether the voltage difference between each module meets the first preset voltage difference range. If yes, there is no need to perform voltage balancing control on each module. Otherwise, each module is charged by controlling the balancing circuit connected in parallel to each module until the voltage difference between each module is less than the preset voltage value.

9. The energy storage control method according to claim 8, characterized in that: Each battery pack in the energy storage system control circuit is connected to a charging control circuit, the charging control circuit includes a switch circuit and a balancing circuit, the output negative electrode of the battery pack is connected in parallel with one of the balancing circuits, the output positive electrode of the battery pack is connected to the switch circuit, and the switch circuit is connected in parallel with one of the balancing circuits, the method further includes: The controller obtains the voltage of each battery pack; The controller determines whether the voltage difference between each battery pack meets the second preset voltage difference range. If so, there is no need to perform voltage balancing control on each battery pack. Otherwise, the controller charges each battery pack by controlling the charging control circuit connected to each battery pack until the voltage difference between each battery pack is less than the preset voltage value.

10. The energy storage control method according to claim 8 or 9, characterized in that: The first preset voltage difference range is greater than 1V and less than 3V, the second preset voltage difference range is greater than 5V, and the preset voltage value is 1V.

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