A liquid cooling device and energy storage system for an energy storage system

Abstract

This invention provides a liquid cooling device and an energy storage system. The liquid cooling device lays a liquid cooling circuit inside a high-voltage box. When the converter module inside the high-voltage box is started, the heat generated by the converter module is dissipated through the high-voltage box liquid cooling circuit. When the switching module is on and the converter module is off, natural heat dissipation is used to cool the high-voltage box. This ensures the safe operation of the high-voltage box while reducing heat dissipation costs.

Description

Technical Field

[0001] This invention relates to the field of system heat dissipation technology, and in particular to a liquid cooling device and energy storage system for an energy storage system. Background Technology

[0002] A battery cluster consists of multiple batteries connected in series or parallel. Each battery cluster is connected to an energy storage converter, which in turn is connected to the power grid to form an energy storage system. The battery cluster, as a key component for storing and releasing electrical energy, is a critical piece of equipment in the energy storage system and directly affects its safe and stable operation. The temperature difference within the battery cluster has a significant impact on the lifespan of the battery modules; therefore, heat dissipation is extremely important for the energy storage system.

[0003] Liquid cooling is a common heat dissipation method for energy storage systems. This involves laying liquid-cooled pipes inside the battery pack to remove the heat generated by the pack. The high-voltage boxes of individual battery clusters, however, rely on natural heat dissipation. While this method solves the heat dissipation problem for the battery clusters, it cannot guarantee the safe operation of the high-voltage boxes. Summary of the Invention

[0004] This invention provides a liquid cooling device and an energy storage system to solve the problem of poor heat dissipation in the high-voltage box of the energy storage system.

[0005] In a first aspect, embodiments of the present invention provide a liquid cooling device for an energy storage system, comprising: a controller, a liquid cooling unit, and multiple high-pressure tank liquid cooling circuits;

[0006] Each high-voltage box liquid cooling circuit is laid in the high-voltage box of the corresponding battery cluster in the energy storage system; the high-voltage box includes a switching module and a converter module; the first end of the switching module and the first end of the converter module are respectively connected to the output end of the corresponding battery cluster, and the second end of the switching module is connected to the DC bus; the second end of the converter module is connected to the DC bus or an external power supply end;

[0007] The controller is used to control the liquid cooler to provide circulating liquid to the high-pressure box liquid cooling circuit when the converter module is started.

[0008] In one possible implementation, the high-pressure tank liquid cooling circuit includes a high-pressure tank liquid cooling plate, a high-pressure tank liquid inlet pipe, and a high-pressure tank liquid return pipe;

[0009] The high-pressure box liquid cooling plate is installed in the corresponding high-pressure box. One end of the high-pressure box liquid inlet pipe is connected to the liquid outlet of the liquid cooling unit, and the other end is connected to the liquid inlet of the corresponding high-pressure box liquid cooling plate. One end of the high-pressure box liquid return pipe is connected to the liquid outlet of the corresponding high-pressure box liquid cooling plate, and the other end is connected to the liquid return port of the liquid cooling unit.

[0010] In one possible implementation, the liquid cooling device further includes a plurality of first solenoid valves;

[0011] Each first solenoid valve is installed on the high-pressure tank liquid cooling circuit of the corresponding battery cluster;

[0012] The controller is also configured to control the first solenoid valve corresponding to the first battery cluster to open when the converter module corresponding to the first battery cluster is started, and to control the first solenoid valve corresponding to the first battery cluster to close when the converter module corresponding to the first battery cluster is turned off.

[0013] The first battery cluster is any battery cluster in the energy storage system.

[0014] In one possible implementation, the controller is specifically used for:

[0015] After the first solenoid valve corresponding to the first battery cluster is opened, the valve opening degree of the first solenoid valve corresponding to the first battery cluster is controlled according to the power of the converter module corresponding to the first battery cluster, and the power is positively correlated with the valve opening degree.

[0016] In one possible implementation, the controller is specifically used for:

[0017] After the first solenoid valve corresponding to the first battery cluster is opened, the valve opening degree of the first solenoid valve corresponding to the first battery cluster is controlled according to the SOC value to be balanced corresponding to the first battery cluster. The SOC value to be balanced is positively correlated with the valve opening degree. The SOC value to be balanced is the difference between the SOC value of the battery cluster and the target SOC value.

[0018] In one possible implementation, the liquid cooling device further includes multiple temperature sensors;

[0019] Each temperature sensor is installed in its corresponding high-voltage box to collect the temperature inside its respective high-voltage box.

[0020] The controller is also used to control the valve opening of the corresponding first solenoid valve based on the temperature inside each high-pressure box.

[0021] In one possible implementation, the liquid cooling unit includes a heat exchanger and a water pump.

[0022] In one possible implementation, the liquid cooling device further includes a liquid cooling circuit for each battery pack in the battery cluster and a second solenoid valve for each battery pack liquid cooling circuit.

[0023] Each battery pack liquid cooling circuit is installed on its corresponding battery pack, and each battery pack liquid cooling circuit is connected to the liquid cooling unit.

[0024] Each of the second solenoid valves is installed on the corresponding battery pack liquid cooling circuit.

[0025] In one possible implementation, the controller is further configured to:

[0026] Based on the length of the target liquid cooling circuit, the initial valve opening of the solenoid valve on the target liquid cooling circuit is determined; the target liquid cooling circuit includes liquid cooling circuits for each battery pack and liquid cooling circuits for the high-voltage box.

[0027] Secondly, embodiments of the present invention provide an energy storage system, which includes the liquid cooling device described in the first aspect above.

[0028] This invention provides a liquid cooling device and an energy storage system. The liquid cooling device lays a liquid cooling circuit inside the high-voltage box. When the switch module is off and the converter module is on, the heat generated by the converter module is dissipated through the high-voltage box liquid cooling circuit. When the switch module is on and the converter module is off, the high-voltage box is cooled by natural heat dissipation. This ensures the safe operation of the high-voltage box and reduces heat dissipation costs. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the structure of the liquid cooling device of the energy storage system provided in the embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the energy storage system provided in an embodiment of the present invention. Detailed Implementation

[0032] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described below in conjunction with the accompanying drawings.

[0034] In one embodiment, the liquid cooling device provided in this embodiment is applied to an energy storage system, such as... Figure 1 As shown, Figure 1 A schematic diagram of an energy storage system for power balancing of battery clusters using a three-phase power distribution terminal is shown. The energy storage system includes a power conversion system (PCS), multiple battery clusters, and a high-voltage box corresponding to each battery cluster. The high-voltage box includes a switching module and a converter module.

[0035] Each battery cluster is connected to the first terminal of the corresponding switch module and the first terminal of the converter module. The second terminal of each switch module is connected to the energy storage converter PCS via a DC bus. The second terminal of each converter module is connected to the energy storage converter PCS or a three-phase power distribution terminal.

[0036] The controller of the energy storage system is used to control the switching modules corresponding to each battery cluster to be balanced to disconnect the connection between the corresponding battery cluster and the DC bus when performing the power balancing task, and to start the converter modules corresponding to the battery clusters to be balanced, so that the three-phase distribution terminal / energy storage converter can perform power balancing for each battery cluster to be balanced. The battery clusters to be balanced can be battery clusters with unbalanced power, or they can be all battery clusters in the energy storage system.

[0037] Specifically, when the battery cluster is performing normal charging and discharging tasks, the switching module controls the on and off of the battery cluster. When the battery cluster is undergoing equalization management, the switching module is turned off and the converter module is turned on, thereby balancing the power of the battery cluster through the converter module.

[0038] Specifically, the converter module can be as follows: Figure 1 The AC-CDC rectifier module shown serves to rectify the AC power from the three-phase distribution terminal into DC power and supply it to the battery pack, or to invert the DC power from the battery pack into AC power and supply it to the three-phase distribution terminal. The three-phase distribution terminal can be a station service distribution terminal, connected to the power grid via a transformer. Alternatively, it can also serve as a three-phase power supply terminal for other external applications.

[0039] In one possible implementation, the converter module ACDC includes a rectifier unit and a DC-DC unit;

[0040] The AC terminal of the rectifier unit is connected to the three-phase power distribution terminal, the DC terminal of the rectifier unit is connected to the first terminal of the DC-DC unit, and the second terminal of the DC-DC unit is connected to the corresponding battery cluster.

[0041] The rectifier unit is a bidirectional synchronous rectifier circuit, and correspondingly, the DC-DC unit is a bidirectional DC-DC circuit. By setting up the bidirectional synchronous rectifier circuit and the bidirectional DC-DC circuit, the power balance of unbalanced battery clusters can be achieved by charging the battery clusters from the three-phase power distribution terminal or discharging them from the battery clusters to the three-phase power distribution terminal.

[0042] In one possible implementation, the converter module includes a fully controlled rectifier circuit for converting between the AC power from the three-phase distribution terminal and the DC power output from the battery cluster.

[0043] In this embodiment, the converter module can also be a DC-DC circuit. When the converter module is a DC-DC circuit, the DC-DC circuit is used to boost the DC power from the energy storage converter and send it to the battery cluster, or to step down the DC power output from the battery cluster and send it to the energy storage converter.

[0044] In one possible implementation, the switching module includes a main contactor; a first end of the main contactor is connected to the battery cluster, and a second end of the main contactor is connected to the DC bus.

[0045] Specifically, such as Figure 1 As shown, the high-voltage box A11 includes a main contactor KM1-1, a secondary contactor KM1-3, a disconnecting switch QS1, a first resistor R1, and a converter module ACCDC1. The first terminals of the main contactor KM1-1, the secondary contactor KM1-3, and the converter module ACCDC1 are all connected to the corresponding battery clusters. The second terminal of the secondary contactor KM1-3 is connected to the first terminal of the first resistor R1. The second terminals of the first resistor R1 and the main contactor KM1-1 are all connected to one terminal of the disconnecting switch QS1. The other terminal of the disconnecting switch QS1 is connected to the DC bus. The second terminal of the converter module ACCDC1 is connected to the three-phase power distribution terminal.

[0046] Specifically, to achieve power balance among battery clusters, the high-voltage box of the energy storage system contains both a switching module and a converter module. The switching module connects the battery clusters to the energy storage converter, enabling normal charging and discharging of the battery clusters. The converter module is used to balance the battery clusters; when the battery clusters are unbalanced, the converter module is activated, using the energy storage converter / three-phase power distribution terminal to achieve power balance among the battery clusters to be balanced. However, in this structure, the converter module generates significant heat during power balancing, preventing the high-voltage box from cooling down naturally.

[0047] Figure 2 This is a schematic diagram of the structure of the liquid cooling device of the energy storage system provided in the embodiment of the present invention, as shown below. Figure 1 As shown, the liquid cooling device includes: a controller, a liquid cooling unit, and multiple high-pressure tank liquid cooling circuits;

[0048] Each high-voltage box liquid cooling circuit is laid in the high-voltage box of the corresponding battery cluster in the energy storage system; the high-voltage box includes a switching module and a converter module; the first end of the switching module and the first end of the converter module are respectively connected to the output end of the corresponding battery cluster, and the second end of the switching module is connected to the DC bus; the second end of the converter module is connected to the DC bus or an external power supply end;

[0049] The controller is used to control the liquid cooler to provide circulating liquid to the high-pressure box liquid cooling circuit when the converter module is started.

[0050] Specifically, in this embodiment, a liquid-cooled circuit is laid inside the high-voltage box. When the battery clusters are undergoing charge equalization, the switching module is off and the converter module is on. The switching transistors in the converter module generate heat, and the controller controls the liquid-cooled circuit to supply circulating fluid to the high-voltage box's liquid-cooled circuit. The circulating fluid carries away the heat generated by the converter module in the high-voltage box. When the battery clusters are undergoing normal charging and discharging, the switching module is on and the converter module is off. Since the switching module is mainly a contactor, it generates relatively little heat during operation and can therefore be cooled by natural heat dissipation. Therefore, the corresponding high-voltage box liquid-cooled circuit does not need to be circulated.

[0051] In one possible implementation, the high-pressure tank liquid cooling circuit includes a high-pressure tank liquid cooling plate, a high-pressure tank liquid inlet pipe, and a high-pressure tank liquid return pipe;

[0052] The high-pressure box liquid cooling plate is installed in the corresponding high-pressure box. One end of the high-pressure box liquid inlet pipe is connected to the liquid outlet of the liquid cooling unit, and the other end is connected to the liquid inlet of the corresponding high-pressure box liquid cooling plate. One end of the high-pressure box liquid return pipe is connected to the liquid outlet of the corresponding high-pressure box liquid cooling plate, and the other end is connected to the liquid return port of the liquid cooling unit.

[0053] In one specific embodiment, the high-voltage box liquid cooling plate is made of aluminum-based material, with a thin tube embedded inside. One end of the thin tube serves as the liquid inlet, and the other end as the liquid outlet. The thin tube inside the liquid cooling plate can be made of copper. The high-voltage box liquid cooling plate can be installed on one end face of the high-voltage box near the converter module for better heat dissipation of the converter module.

[0054] As another specific embodiment, the high-pressure box liquid cooling plate can also be a split liquid cooling plate, which includes: a liquid cooling plate and a top cover plate welded to the liquid cooling plate; a cold liquid flow area is formed between the liquid cooling plate and the top cover plate, and the cold liquid flow area is provided with main heat dissipation teeth located between the liquid inlet and the liquid outlet of the cold liquid flow area, and guide teeth located between the liquid inlet and the main heat dissipation teeth; the guide teeth are arranged diverging from the water nozzle edge of the liquid inlet to each main heat dissipation tooth, forcibly diverting the cold liquid flowing in from the liquid inlet; the cold liquid flows in from the liquid inlet, passes through the guide channel between each guide tooth, and flows into the main heat dissipation channel between each main heat dissipation tooth, realizing the diversion of the cold liquid between each main heat dissipation tooth. The liquid inlet and liquid outlet of the liquid cooling plate are located on the top cover plate.

[0055] In one possible implementation, such as Figure 2 As shown, the liquid cooling device also includes a plurality of first solenoid valves C1;

[0056] Each first solenoid valve C1 is installed on the high-pressure tank liquid cooling circuit of the corresponding battery cluster;

[0057] The controller is also used to control the first solenoid valve C1 corresponding to the first battery cluster to open when the converter module corresponding to the first battery cluster is started, and to control the first solenoid valve C1 corresponding to the first battery cluster to close when the converter module corresponding to the first battery cluster is turned off.

[0058] The first battery cluster is any battery cluster in the energy storage system.

[0059] In this embodiment, the first solenoid valve can be installed on the liquid inlet pipe of the high-pressure box near the liquid cooler unit, and is used to connect and disconnect the liquid cooler unit from the liquid cooling circuit of the high-pressure box.

[0060] In one possible implementation, the liquid cooling unit includes a heat exchanger and a water pump.

[0061] In one possible implementation, the liquid cooling device further includes a liquid cooling circuit for each battery pack in the battery cluster and a second solenoid valve (C) corresponding to each battery pack liquid cooling circuit. 2-1 C 2-2 ...C 2-n );

[0062] Each battery pack liquid cooling circuit is installed on its corresponding battery pack, and each battery pack liquid cooling circuit is connected to the liquid cooling unit.

[0063] Each of the second solenoid valves is installed on the corresponding battery pack liquid cooling circuit.

[0064] In this embodiment, as Figure 2As shown, each battery pack liquid cooling circuit includes a battery pack liquid cooling plate, a second solenoid valve, a battery pack liquid inlet pipe, and a battery pack liquid return pipe; the liquid cooling device also includes a main liquid inlet pipe and a main liquid return pipe.

[0065] The liquid cooler unit's outlet is connected to the main liquid inlet pipe. One end of each battery pack's liquid inlet pipe and the high-voltage box's liquid inlet pipe is connected to the main liquid inlet pipe, and the other end of each battery pack's liquid inlet pipe is connected to the inlet of its corresponding battery pack liquid cooling plate. The outlet of the battery pack's liquid cooling plate is connected to one end of the battery pack's return liquid pipe, and the other end of the battery pack's return liquid pipe is connected to the main return liquid pipe. The other end of the high-voltage box's liquid inlet pipe is connected to the inlet of the high-voltage box's liquid cooling plate, and the outlet of the high-voltage box's liquid cooling plate is connected to one end of the high-voltage box's return liquid pipe, and the other end of the high-voltage box's return liquid pipe is connected to the main return liquid pipe.

[0066] In one specific embodiment, the battery pack liquid cooling plate is made of aluminum-based material, and a thin tube is embedded inside the liquid cooling plate. One end of the thin tube is the liquid inlet of the battery pack liquid cooling plate, and the other end is the liquid outlet of the battery pack liquid cooling plate. The thin tube inside the battery pack liquid cooling plate can be made of copper.

[0067] As another specific embodiment, the battery pack liquid cooling plate can also be a split liquid cooling plate, which includes: a liquid cooling plate and a top cover plate welded to the liquid cooling plate; a cold liquid flow area is formed between the liquid cooling plate and the top cover plate, and the cold liquid flow area is provided with main heat dissipation teeth located between the liquid inlet and the liquid outlet of the cold liquid flow area, and guide teeth located between the liquid inlet and the main heat dissipation teeth; the guide teeth are arranged diverging from the water nozzle edge of the liquid inlet to each main heat dissipation tooth, forcibly diverting the cold liquid flowing in from the liquid inlet; the cold liquid flows in from the liquid inlet, passes through the guide channel between each guide tooth, and flows into the main heat dissipation channel between each main heat dissipation tooth, realizing the diversion of the cold liquid between each main heat dissipation tooth. The liquid inlet and liquid outlet of the liquid cooling plate are located on the top cover plate.

[0068] In this embodiment, one end of the heat exchanger serves as the liquid outlet of the liquid chiller and is connected to the main liquid inlet pipe, while the other end of the heat exchanger is connected to one end of the water pump, and the other end of the water pump serves as the liquid return port of the liquid chiller and is connected to the main liquid return pipe.

[0069] Specifically, in practical applications, the battery packs and high-voltage boxes on a battery cluster are usually mounted on the same multi-layer bracket. To ensure balanced heat dissipation for the battery packs, the liquid cooling plates for each battery pack are all mounted on the same end face of the battery pack. Similarly, the liquid cooling plates for the high-voltage box are also mounted on the same end face of the high-voltage box as the battery packs. For example, the liquid cooling plates for the battery packs are all mounted at the bottom of each battery pack, and the liquid cooling plates for the high-voltage box are also mounted at the bottom of the high-voltage box to ensure uniform distribution of the liquid cooling plates.

[0070] Specifically, the controller controls the on / off state of each liquid cooling circuit by controlling the opening and closing of each first and second solenoid valve. When the first battery cluster is in a normal charging / discharging state, the controller controls the second solenoid valve corresponding to each battery pack in the first battery cluster to open, and controls the first solenoid valve of the high-voltage box corresponding to the first battery cluster to close. When the first battery cluster is in an equalization state, the controller controls the second solenoid valve corresponding to each battery pack in the first battery cluster to open, and simultaneously controls the first solenoid valve of the high-voltage box corresponding to the first battery cluster to open. When a battery pack in the first battery cluster exits, the corresponding second solenoid valve is controlled to close.

[0071] The first battery cluster can be any battery cluster in the energy storage system.

[0072] In one possible implementation, the controller is specifically used for:

[0073] After the first solenoid valve corresponding to the first battery cluster is opened, the valve opening degree of the first solenoid valve corresponding to the first battery cluster is controlled according to the power of the converter module corresponding to the first battery cluster, and the power is positively correlated with the valve opening degree.

[0074] In this embodiment, the higher the power of the converter module, the higher the heat it releases. Therefore, a large flow rate of circulating fluid is needed to remove the heat released by the converter module.

[0075] In one possible implementation, the controller is specifically used for:

[0076] After the first solenoid valve corresponding to the first battery cluster is opened, the valve opening degree of the first solenoid valve corresponding to the first battery cluster is controlled according to the SOC value to be balanced corresponding to the first battery cluster. The SOC value to be balanced is positively correlated with the valve opening degree. The SOC value to be balanced is the difference between the SOC value of the battery cluster and the target SOC value.

[0077] In this embodiment, the target SOC value is the SOC value used to determine the completion of battery cluster charge balancing. This can be the SOC value for full charge, full discharge, or any SOC value other than full charge or full discharge. To ensure consistent charging and discharging progress among battery clusters, reduce the time difference between equalization completion times, and accelerate the balancing process, the equalization power of the converter module is determined based on the SOC value to be equalized for each battery cluster during charge balancing. The SOC value to be equalized is positively correlated with the equalization power. Therefore, the larger the SOC value to be equalized, the greater the power of the converter module and the greater the heat generated by the high-voltage box, requiring a larger flow rate of circulating fluid to remove the heat released by the converter module. The controller provided in this embodiment directly uses the SOC value to be equalized to determine the valve opening of the first solenoid valve, enabling advance adjustment of the valve opening based on the SOC value, thereby improving the heat dissipation effect of the liquid cooling device.

[0078] In one possible implementation, the liquid cooling device further includes multiple temperature sensors;

[0079] Each temperature sensor is installed in its corresponding high-voltage box to collect the temperature inside its respective high-voltage box.

[0080] The controller is also used to control the valve opening of the corresponding first solenoid valve based on the temperature inside each high-pressure box.

[0081] In this embodiment, the controller can also determine the valve opening degree of the first solenoid valve based on the temperature of the high-pressure box and the power of the converter module.

[0082] Specifically, the temperature of the high-pressure box and the power of the converter module are weighted and summed to obtain a comprehensive reference value. The valve opening of the first solenoid valve is then determined based on the comprehensive reference value, where the valve opening of the first solenoid valve is positively correlated with the comprehensive reference value.

[0083] In one possible implementation, the controller is further configured to:

[0084] Based on the length of the target liquid cooling circuit, the initial valve opening of the solenoid valve on the target liquid cooling circuit is determined; the target liquid cooling circuit includes liquid cooling circuits for each battery pack and liquid cooling circuits for the high-voltage box.

[0085] Specifically, the length of the target liquid cooling circuit provided in this embodiment is the length of the pipe from the target liquid cooling plate to the liquid cooling unit, wherein the target liquid cooling plate includes the high-pressure box liquid cooling plate and the battery pack liquid cooling plate. Since the longer the target liquid cooling circuit, the slower the flow rate of the circulating liquid at the target liquid cooling plate, and the less heat is carried away, this embodiment can determine the initial valve opening of the solenoid valves on the target liquid cooling circuit according to the length of the target liquid cooling circuit, and after determining the initial valve opening of each solenoid valve, the valve opening is opened to the initial valve opening when the first solenoid valve / second solenoid valve just opens.

[0086] Specifically, for the high-voltage box liquid cooling circuit, the valve opening of the first solenoid valve corresponding to the high-voltage box is determined according to the length of the high-voltage box liquid cooling circuit. When the converter module starts, the valve opening of the first solenoid valve corresponding to the high-voltage box is opened to the initial valve opening. Then, the valve opening of the first solenoid valve is adjusted according to the power of the converter module. This can avoid the problem of uneven heat dissipation of the liquid cooling circuit caused by different placement positions of various modules (battery pack and high-voltage box), and can also use a higher flow rate of circulating liquid to quickly dissipate heat from modules with large heat generation, thereby improving the heat dissipation effect of the liquid cooling device.

[0087] This invention provides an energy storage system that includes the liquid cooling device described above.

[0088] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A liquid cooling device for an energy storage system, characterized in that, include: Controller, liquid cooling unit and multiple high-pressure tank liquid cooling circuits; Each high-voltage box liquid cooling circuit is laid in the high-voltage box of the corresponding battery cluster in the energy storage system; the high-voltage box includes a switching module and a converter module; the first end of the switching module and the first end of the converter module are respectively connected to the output end of the corresponding battery cluster, and the second end of the switching module is connected to the DC bus; the second end of the converter module is connected to the DC bus or an external power supply end; The controller is used to control the liquid cooler to provide circulating liquid to the high-pressure box liquid cooling circuit when the converter module is started; The liquid cooling device also includes a plurality of first solenoid valves; Each first solenoid valve is installed on the high-pressure tank liquid cooling circuit of the corresponding battery cluster; The controller is also configured to control the first solenoid valve corresponding to the first battery cluster to open when the converter module corresponding to the first battery cluster is started, and to control the first solenoid valve corresponding to the first battery cluster to close when the converter module corresponding to the first battery cluster is turned off. The first battery cluster is any battery cluster in the energy storage system.

2. The liquid cooling device for the energy storage system according to claim 1, characterized in that, The high-pressure box liquid cooling circuit includes a high-pressure box liquid cooling plate, a high-pressure box liquid inlet pipe, and a high-pressure box liquid return pipe. The high-pressure box liquid cooling plate is installed in the corresponding high-pressure box. One end of the high-pressure box liquid inlet pipe is connected to the liquid outlet of the liquid cooling unit, and the other end is connected to the liquid inlet of the corresponding high-pressure box liquid cooling plate. One end of the high-pressure box liquid return pipe is connected to the liquid outlet of the corresponding high-pressure box liquid cooling plate, and the other end is connected to the liquid return port of the liquid cooling unit.

3. The liquid cooling device for the energy storage system according to claim 1, characterized in that, The controller is specifically used for: After the first solenoid valve corresponding to the first battery cluster is opened, the valve opening degree of the first solenoid valve corresponding to the first battery cluster is controlled according to the power of the converter module corresponding to the first battery cluster, and the power is positively correlated with the valve opening degree.

4. The liquid cooling device for the energy storage system according to claim 1, characterized in that, The controller is specifically used for: After the first solenoid valve corresponding to the first battery cluster is opened, the valve opening degree of the first solenoid valve corresponding to the first battery cluster is controlled according to the SOC value to be balanced corresponding to the first battery cluster. The SOC value to be balanced is positively correlated with the valve opening degree. The SOC value to be balanced is the difference between the SOC value of the battery cluster and the target SOC value.

5. The liquid cooling device for the energy storage system according to claim 1, characterized in that, The liquid cooling device also includes multiple temperature sensors; Each temperature sensor is installed in its corresponding high-voltage box to collect the temperature inside its respective high-voltage box. The controller is also used to control the valve opening of the corresponding first solenoid valve based on the temperature inside each high-pressure box.

6. The liquid cooling device for the energy storage system according to claim 1, characterized in that, The liquid cooling unit includes a heat exchanger and a water pump.

7. The liquid cooling device for the energy storage system according to claim 1, characterized in that, The liquid cooling device also includes a liquid cooling circuit for each battery pack in the battery cluster and a second solenoid valve for each liquid cooling circuit for the battery pack. Each battery pack liquid cooling circuit is installed on its corresponding battery pack, and each battery pack liquid cooling circuit is connected to the liquid cooling unit. Each of the second solenoid valves is installed on the corresponding battery pack liquid cooling circuit.

8. The liquid cooling device for the energy storage system according to claim 7, characterized in that, The controller is also used for: Based on the length of the target liquid cooling circuit, the initial valve opening of the solenoid valve on the target liquid cooling circuit is determined; the target liquid cooling circuit includes liquid cooling circuits for each battery pack and liquid cooling circuits for the high-voltage box.

9. An energy storage system, characterized in that, Includes the liquid cooling device as described in any one of claims 1 to 8.

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