Cooling circulation method and energy storage system

Abstract

The invention relates to the technical field of energy storage, and provides a cooling circulation method and an energy storage system.The method comprises the steps that the temperature of cooling liquid is obtained; under the condition that the temperature of the cooling liquid is smaller than the threshold temperature of the cooling liquid, an external water pump is started to increase the flow speed of the cooling liquid to a preset flow speed range, and the external water pump is installed on a main circuit between the liquid cooling unit and the battery pack; and when the temperature of the cooling liquid is larger than or equal to the threshold temperature of the cooling liquid, the external water pump is closed. According to the method, under the condition that the temperature of the cooling liquid is lower than a threshold value, namely, the viscosity of the cooling liquid is too large, the flow speed of the cooling liquid becomes slow, and the cooling effect is poor, the flow speed of the cooling liquid is increased by opening an external water pump between the liquid cooling unit and the battery pack, the flow speed of the cooling liquid can be kept within the flow speed range needed by cooling, and the cooling effect is kept; the problem that in the prior art, the viscosity of immersion liquid is increased and the flow speed is decreased under the low-temperature working condition, and consequently the cooling effect is reduced is solved.

Description

Technical Field

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

[0002] The energy storage system is equipped with battery cells. The battery cells will generate heat during the charging and discharging process, causing the battery cell temperature to rise. If the temperature of the battery cells is not controlled, it may lead to reduced battery cell efficiency, shortened lifespan or thermal runaway. The natural heat dissipation of the battery cells cannot maintain the temperature within the working range, so an external cooling system is required.

[0003] Immersion liquid cooling is a cooling system used in energy storage devices. The battery pack is filled with insulating immersion coolant, and the coolant is in direct contact with the battery cells for heat exchange. The energy storage system has a liquid cooling unit and liquid cooling pipelines. The immersion coolant flows in the pipeline and is cooled by the liquid cooling unit to control the temperature of the battery cells. Immersion liquid cooling has good temperature control effect and safety, can effectively reduce the temperature difference between battery cells, and reduce the risk of thermal runaway. It is a very promising liquid cooling technology for energy storage devices.

[0004] In immersion energy storage technology, the battery pack structure can be eliminated and the battery cells can be directly arranged in the battery cluster in a multi-layer form, thereby achieving the goals of improving system integration, simplifying structure and reducing costs.

[0005] However, immersion coolant is generally a mixture of organic liquids such as mineral oil, silicone oil, and synthetic oil. The viscosity of this immersion fluid will increase as the temperature decreases. The higher viscosity will significantly increase the pipe resistance of the liquid cooling system, causing the flow rate of the water pump to decrease, affecting the temperature control ability of the system. Summary of the invention

[0006] The main purpose of the present application is to provide a cooling cycle method and an energy storage system, so as to at least solve the problem in the prior art that the viscosity of the immersion liquid increases and the flow rate decreases under low temperature conditions, resulting in reduced cooling effect.

[0007] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a cooling circulation method is provided, which is used in an energy storage system, and the method includes: obtaining the coolant temperature; when the coolant temperature is less than the coolant threshold temperature, starting an external water pump to increase the flow rate of the coolant to a preset flow rate range, wherein the external water pump is installed on the main line between the liquid cooling unit and the battery pack; when the coolant temperature is greater than or equal to the coolant threshold temperature, shutting down the external water pump.

[0008] Optionally, after starting the external water pump, the method further includes: obtaining a water pump characteristic curve of the external water pump, the water pump characteristic curve characterizing the ability of the external water pump to increase the flow rate of the coolant, the water pump characteristic curve at least including a flow-head curve of the external water pump, the flow-head curve characterizing the relationship between the flow rate of the coolant and the head of the external water pump, the head of the external water pump is directly proportional to the rotational speed of the external water pump; determining the rotational speed of the external water pump according to the water pump characteristic curve of the external water pump, the flow rate of the coolant and the preset flow rate range of the coolant.

[0009] Optionally, after starting the external water pump, the method further includes: obtaining the maximum pressure-bearing capacity of the pipeline of the energy storage system and the maximum pressure-bearing capacity of the liquid cooling unit; determining the maximum pressure threshold of the coolant according to the maximum pressure-bearing capacity of the pipeline of the energy storage system and the maximum pressure-bearing capacity of the liquid cooling unit; and determining that the current speed of the external water pump reaches the maximum speed when the real-time pressure of the coolant reaches the maximum pressure threshold.

[0010] Optionally, the method further includes: obtaining the type of the coolant; obtaining a fourth mapping relationship, wherein the fourth mapping relationship represents the relationship between the type of the coolant and the threshold temperature of the coolant; and determining the coolant threshold temperature based on the type of the coolant and the fourth mapping relationship.

[0011] Optionally, when the coolant temperature is less than the coolant threshold temperature, the external water pump is started, including: when the coolant temperature is less than the coolant threshold temperature, obtaining a first temperature difference and / or a target ratio, the first temperature difference being the difference between the coolant temperature and the coolant threshold temperature, and the target ratio being the ratio of the coolant temperature to the coolant threshold temperature; obtaining a first mapping relationship and a second mapping relationship, the first mapping relationship representing the relationship between the difference between the coolant temperature and the coolant threshold temperature and the rotational speed of the external water pump, and the second mapping relationship representing the relationship between the ratio of the coolant temperature to the coolant threshold temperature and the rotational speed of the external water pump; determining a target rotational speed of the external water pump according to the first temperature difference and the first mapping relationship, and / or determining a target rotational speed of the external water pump according to the target ratio and the second mapping relationship, and controlling the external water pump to operate at the target rotational speed.

[0012] Optionally, when the coolant temperature is less than a coolant threshold temperature, the external water pump is started, including: when the coolant temperature is less than the coolant threshold temperature, obtaining a target temperature change rate of the coolant, the target temperature change rate of the coolant being the rate of change of the temperature of the coolant within a preset time period; obtaining a third mapping relationship, the third mapping relationship representing the relationship between the temperature change rate of the coolant and the rotational speed of the external water pump; determining a target rotational speed of the external water pump according to the target temperature change rate of the coolant and the third mapping relationship, and controlling the external water pump to operate at the target rotational speed.

[0013] Optionally, the coolant temperature is negatively correlated with the rotation speed of the external water pump.

[0014] Optionally, the energy storage system further includes a first three-way valve and a second three-way valve, and the method further includes: when the coolant temperature is lower than a coolant threshold temperature, connecting the external water pump to a main line between the liquid cooling unit and the battery pack through the first three-way valve and the second three-way valve; when the coolant temperature is greater than or equal to the coolant threshold temperature, connecting the liquid cooling unit and the battery pack through a branch pipeline through the first three-way valve and the second three-way valve, and short-circuiting the external water pump.

[0015] Optionally, there are multiple battery packs, and the method further includes: obtaining the battery cell temperature of each battery pack; obtaining the battery cell low temperature threshold temperature and the battery cell high temperature threshold temperature; when the highest battery cell temperature is lower than the battery cell low temperature threshold temperature, controlling the energy storage system to a heating mode, wherein the heating mode is a mode for heating the coolant; when the lowest battery cell temperature is higher than the battery cell high temperature threshold temperature, controlling the energy storage system to a cooling mode, wherein the cooling mode is a mode for cooling the coolant; when the highest battery cell temperature is higher than or equal to the battery cell low temperature threshold temperature, and the lowest battery cell temperature is lower than or equal to the battery cell high temperature threshold temperature, controlling the energy storage system to a self-circulation mode, wherein the self-circulation mode is a mode in which the coolant is not cooled or heated.

[0016] Optionally, controlling the energy storage system to a cooling mode includes: obtaining the ambient temperature of the energy storage system, and determining the difference between the ambient temperature and the coolant temperature as a second temperature difference; when the second temperature difference is less than a preset temperature difference, cooling the coolant using an air direct cooling mode, wherein the air direct cooling mode is a mode in which the coolant is cooled using ambient air; when the second temperature difference is greater than or equal to the preset temperature difference, cooling the coolant using a refrigeration cycle mode, wherein the refrigeration cycle mode is a mode in which the coolant is cooled using a refrigeration phase change medium.

[0017] According to another aspect of the present application, there is provided an energy storage system, comprising: a liquid cooling unit; a battery pack connected to the liquid cooling unit via a pipeline, the liquid cooling unit being used to cool the battery pack via a coolant; and an external water pump installed on a main line between the liquid cooling unit and the battery pack, the external water pump being used to increase the flow rate of the coolant.

[0018] Optionally, it also includes: a first three-way valve, having an inlet, an outlet and a bypass port, the inlet of the first three-way valve is connected to the battery pack through a pipeline, the outlet of the first three-way valve is connected to the external water pump through a pipeline, and the bypass port of the first three-way valve is connected to the branch pipeline; a second three-way valve, having an inlet, an outlet and a bypass port, the inlet of the second three-way valve is connected to the external water pump through a pipeline, the outlet of the first three-way valve is connected to the liquid cooling unit through a pipeline, and the bypass port of the first three-way valve is connected to the branch pipeline.

[0019] Optionally, the liquid cooling unit has a liquid outlet and a liquid return port, and the liquid outlet is connected to the liquid outlet pipe, and the liquid return port is connected to the first liquid return pipe; there are multiple battery packs, and one battery pack includes at least one battery cell, one end of the battery pack is connected to the liquid outlet pipe, and the other end of the battery pack is connected to the first liquid return pipe, wherein the liquid cooling unit is used to provide cooling liquid to each of the battery cells via the liquid outlet, and is also used to recover the cooling liquid in each of the battery cells via the liquid return port.

[0020] Optionally, the energy storage system further includes: a plurality of valves, each of the valves being installed on a pipeline between the corresponding battery pack and the liquid outlet pipe, and the valves correspond to the battery packs one by one.

[0021] Optionally, the energy storage system further includes: a plurality of battery cell temperature sensors installed on the surface of the battery cells, one battery pack including at least one battery cell temperature sensor, and one battery cell temperature sensor used to detect the temperature of at least one battery cell; an ambient temperature sensor installed outside the cabinet of the energy storage system for monitoring the external ambient temperature of the energy storage system; a coolant temperature sensor installed in the liquid cooling unit for monitoring the temperature of the coolant.

[0022] According to another aspect of the present application, there is provided an energy storage system, comprising: a liquid cooling unit; a battery pack connected to the liquid cooling unit via a pipeline, the liquid cooling unit being used to cool the battery pack via a coolant; an external water pump, the external water pump being installed on a main path between the liquid cooling unit and the battery pack, the external water pump being used to increase the flow rate of the coolant; and a controller being used to start the external water pump when the coolant temperature is less than a coolant threshold temperature to increase the flow rate of the coolant to a preset flow rate range, and to shut down the external water pump when the coolant temperature is greater than or equal to the coolant threshold temperature, wherein the external water pump is installed on the main path between the liquid cooling unit and the battery pack.

[0023] The beneficial effects of the present application include: first obtaining the coolant temperature; then, when the coolant temperature is less than the coolant threshold temperature, starting the external water pump to increase the flow rate of the coolant to a preset flow rate range, wherein the external water pump is installed on the main line between the liquid cooling unit and the battery pack; and finally, when the coolant temperature is greater than or equal to the coolant threshold temperature, shutting down the external water pump. When the coolant temperature is lower than the threshold, that is, the coolant viscosity is too high, the coolant flow rate slows down, resulting in poor cooling effect, this method increases the coolant flow rate by turning on the external water pump between the liquid cooling unit and the battery pack, so that the coolant flow rate can be kept within the flow rate range required for cooling, maintaining the cooling effect, and solving the problem in the prior art that the viscosity of the immersion liquid increases and the flow rate decreases under low temperature conditions, resulting in reduced cooling effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings constituting part of the present application are used to provide a further understanding of the present application. The exemplary embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0025] Figure 1 A schematic diagram of the structure of an energy storage system provided according to an embodiment of the present application is shown;

[0026] Figure 2 A schematic diagram of the structure of another energy storage system provided according to an embodiment of the present application is shown;

[0027] Figure 3 A schematic diagram of the structure of another energy storage system provided according to an embodiment of the present application is shown;

[0028] Figure 4 A hardware structure block diagram of a mobile terminal for executing a cooling cycle method provided in an embodiment of the present application is shown;

[0029] Figure 5 A schematic flow chart of a cooling cycle method provided according to an embodiment of the present application is shown;

[0030] Figure 6 A schematic flow chart of another cooling cycle method provided according to an embodiment of the present application is shown.

[0031] The above drawings include the following reference numerals:

[0032] 102. Processor; 104. Memory; 106. Transmission device; 108. Input / output device; 100. Liquid cooling unit; 110. Liquid outlet; 120. Liquid return outlet; 130. Liquid outlet pipe; 131. Valve; 140. Liquid return pipe; 150. Branch pipeline; 200. Battery pack; 300. External water pump; 400. First three-way valve; 500. Second three-way valve. DETAILED DESCRIPTION

[0033] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0034] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application.

[0035] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0036] As introduced in the background technology, in the existing immersion energy storage technology, the immersion coolant is generally a mixture of organic liquids such as mineral oil, silicone oil, and synthetic oil. The viscosity of this immersion liquid will increase as the temperature decreases. The higher viscosity will significantly increase the pipe resistance of the liquid cooling system, causing the flow rate of the water pump to decrease, affecting the temperature control ability of the system. In order to solve the problem in the prior art that the viscosity of the immersion liquid increases and the flow rate decreases under low temperature conditions, resulting in a decrease in cooling effect, the embodiments of the present application provide a cooling cycle method and energy storage system.

[0037] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0038] Figure 1 A schematic diagram of the structure of an energy storage system provided according to an embodiment of the present application is shown in FIG. Figure 1 As shown, the energy storage system includes: a liquid cooling unit 100; a battery pack 200, which is connected to the liquid cooling unit 100 through a pipeline, and the liquid cooling unit 100 is used to cool the battery pack 200 through a coolant; an external water pump 300, which is installed on the main line between the liquid cooling unit 100 and the battery pack 200, and the external water pump 300 is used to increase the flow rate of the coolant.

[0039] Specifically, the cooling system of the energy storage system adopts immersion liquid cooling. The coolant of immersion liquid cooling is generally a mixture of organic liquids such as mineral oil, silicone oil, and synthetic oil. The viscosity of this immersion liquid will increase with the decrease of temperature. The higher viscosity will significantly increase the pipe resistance of the liquid cooling system, causing the flow rate of the water pump to decrease, affecting the temperature control ability of the system. Based on the above problems, Figure 1 As shown, the above embodiment of the present application installs an external water pump 300 on the main line between the liquid cooling unit 100 and the battery pack 200. When the temperature of the coolant is lower than the set coolant threshold temperature, it indicates that the coolant solidifies, that is, the coolant flow rate is reduced and cannot meet the coolant flow rate requirements currently required for cooling the battery pack. At this time, the external water pump 300 is started to increase the flow rate of the coolant. By increasing the flow rate of the coolant, the coolant flow rate is kept within the required flow rate range for cooling, ensuring that the heat of the battery pack 200 can be taken away more effectively. At the same time, the temperature balance between the cells inside the battery pack is also enhanced to prevent the battery from being overcooled, thereby ensuring battery performance and extending its life. When the coolant temperature reaches or exceeds the coolant threshold temperature, the system will turn off the external water pump 300 to avoid unnecessary energy consumption and overcooling, and maintain efficient operation of the system.

[0040] That is, the above-mentioned energy storage system of the present application controls the external water pump installed on the main line between the liquid cooling unit and the above-mentioned battery pack to increase the flow rate of the coolant when the flow rate of the coolant decreases, so that the flow rate of the coolant is maintained within the required flow rate range required for cooling, thereby ensuring the cooling requirements of the battery pack.

[0041] Furthermore, in order to avoid unnecessary energy consumption and overcooling and maintain efficient operation of the system, the system will shut down the external water pump when the coolant temperature is greater than or equal to the coolant threshold temperature, that is, when the coolant flow rate meets the cooling requirements. If the external water pump is installed on the main line between the liquid cooling unit and the above-mentioned battery pack, after the external water pump is turned off, the main line between the liquid cooling unit and the above-mentioned battery pack will not be conductive, so that the liquid cooling unit and the battery pack are not a closed loop, and the coolant cannot flow between the liquid cooling unit and the battery pack, which will cause a cooling system failure.

[0042] In order to avoid the above problems, this embodiment adds two three-way valves and a parallel branch with an external water pump (i.e. Figure 2 Middle branch pipeline 150). That is, Figure 2 As shown, the energy storage system also includes: a first three-way valve 400, having an inlet, an outlet and a bypass port, the inlet of the first three-way valve 400 is connected to the battery pack 200 through a pipeline, the outlet of the first three-way valve 400 is connected to the external water pump 300 through a pipeline, and the bypass port of the first three-way valve 400 is connected to the branch pipeline 150; a second three-way valve 500, having an inlet, an outlet and a bypass port, the inlet of the second three-way valve 500 is connected to the external water pump 300 through a pipeline, the outlet of the first three-way valve 400 is connected to the liquid cooling unit 100 through a pipeline, and the bypass port of the first three-way valve 400 is connected to the branch pipeline 150.

[0043] By controlling the conducting pipelines of the two three-way valves, the selection between the branch where the external water pump is located and the parallel branch can be realized. That is, when the coolant temperature is lower than the set coolant threshold temperature, the external water pump 300 is turned on, the pipeline between the inlet and the outlet of the first three-way valve 400 is conducted, the pipeline between the inlet and the bypass port of the first three-way valve 400 is closed, the pipeline between the inlet and the outlet of the second three-way valve 500 is conducted, and the pipeline between the inlet and the bypass port of the second three-way valve 500 is closed, so that the coolant flows through the pipeline where the external water pump 300 is located to increase the coolant flow rate. When the coolant temperature reaches or exceeds the coolant threshold temperature, the external water pump 300 is closed, the pipeline between the inlet and the bypass port of the first three-way valve 400 is connected, the pipeline between the inlet and the outlet of the first three-way valve 400 is closed, the pipeline between the inlet and the bypass port of the second three-way valve 500 is connected, and the pipeline between the inlet and the outlet of the second three-way valve 500 is closed, so that the coolant flows through the pipeline where the branch pipeline 150 is located, so that the coolant can circulate normally between the liquid cooling unit and the battery pack.

[0044] In addition, the above energy storage system also includes other structures, such as Figure 2 As shown, the liquid cooling unit 100 has a liquid outlet 110 and a liquid return port 120, and the liquid outlet 110 is connected to the liquid outlet pipe 130, and the liquid return port 120 is connected to the first liquid return pipe 140; there are multiple battery packs 200, and one battery pack 200 includes at least one battery cell (not shown in the figure), one end of the battery pack 200 is connected to the liquid outlet pipe 130, and the other end of the battery pack 200 is connected to the first liquid return pipe 140, wherein the liquid cooling unit 100 is used to provide cooling liquid to each of the battery cells via the liquid outlet 110, and is also used to recover the cooling liquid in each of the battery cells via the liquid return port 120.

[0045] Based on the above structure, the liquid cooling unit delivers coolant to the battery pack through the liquid outlet, and then recovers the coolant through the liquid return port, forming a closed cooling cycle to cool the battery pack.

[0046] like Figure 2 As shown, the energy storage system further includes: a plurality of valves 131 , each of the valves 131 is respectively installed on a pipeline between the corresponding battery pack 200 and the liquid outlet pipe 130 , and the valves 131 correspond to the battery packs 200 one by one.

[0047] In the immersion liquid-cooled energy storage system, the design of one valve for each battery pack is mainly to achieve independent control of the coolant flow of each battery pack, thereby improving the thermal management efficiency and flexibility of the system.

[0048] Specifically, one valve corresponds to one battery pack, which allows one valve to individually control the flow of coolant flowing through each battery pack. In thermal management, different battery packs may generate different amounts of heat due to factors such as charge and discharge status and aging, so different coolant flows are required to regulate the temperature. Through independent valve control, the distribution of coolant can be optimized according to the specific needs of each battery pack to ensure accurate temperature control.

[0049] In addition, the design of one battery pack corresponding to one valve means that if a battery pack in the system fails (such as leaking, damaged, etc.), the corresponding valve can be closed to isolate the battery pack to prevent the loss of coolant or the failure from affecting the operation of the entire system. And if a battery pack needs to be inspected or maintained, only the valve corresponding to the battery pack can be closed to stop the flow of coolant, so that the battery pack can be maintained separately. In this way, the faulty battery pack can be repaired or replaced without affecting the normal operation of other battery packs, thus providing a safe and convenient environment for maintenance operations.

[0050] In the immersion liquid-cooled energy storage system, valves can also be used to adjust the pressure and flow balance of the entire system. In a liquid-cooled system with multiple battery packs in parallel or series, a valve is set for each battery pack. By adjusting the opening of each valve, the coolant can be evenly distributed among the battery packs to avoid temperature control problems caused by fluid dynamics imbalance.

[0051] In addition, in some cases, if the temperature of some battery packs in the system is already below the set threshold and no further cooling is required, then a valve is set for each battery pack. By closing the valve corresponding to this battery pack, the coolant flow in this battery pack can be reduced or stopped, so that the coolant no longer passes through this battery pack, but flows directly to other battery packs that need to be cooled. This can save energy and improve the energy efficiency of the system. If there is a design where multiple battery packs correspond to one valve, then if one of the battery packs does not need further cooling, the valve cannot be closed to ensure the normal cooling of other battery packs. This will cause the coolant to flow through the battery packs that do not need cooling, resulting in a waste of resources.

[0052] In short, the design of one valve for each battery pack is the key to achieving refined and intelligent thermal management in the immersion liquid cooling system. The independent control capability of the valve can not only solve the temperature control problem of each battery pack in a targeted manner, but also provide effective isolation and protection measures when the system fails or requires maintenance.

[0053] In order to detect the temperature of the battery pack, the ambient temperature of the energy storage system and the coolant temperature in real time, the energy storage system further includes: a plurality of battery cell temperature sensors installed on the surface of the battery cells, one battery pack includes at least one of the battery cell temperature sensors, and one of the battery cell temperature sensors is used to detect the temperature of at least one of the battery cells; an ambient temperature sensor installed on the outside of the cabinet of the energy storage system to monitor the external ambient temperature of the energy storage system; a coolant temperature sensor installed in the liquid cooling unit to monitor the temperature of the coolant.

[0054] Specifically, in a battery pack, one battery cell temperature sensor can be installed on the surface of one battery cell, or the same battery cell temperature sensor can be installed on the surfaces of multiple battery cells. The average value of the values ​​collected by all battery cell temperature sensors in the battery pack is the temperature of the battery pack. By detecting the temperature of the battery pack in real time, it is possible to promptly detect whether the temperature of the battery pack is abnormal, and use a cooling system (liquid cooling unit, coolant, etc.) to cool the battery pack when the temperature of the battery pack is too high. Real-time detection of the temperature of the coolant can promptly detect when the temperature of the coolant drops too low, and can promptly determine that the viscosity of the coolant is too high, resulting in an increase in the pipe resistance of the liquid cooling system and a decrease in the flow rate.

[0055] In a specific embodiment, an energy storage system is equipped with an immersion battery pack, a liquid cooling circulation loop, a liquid cooling unit, an external water pump, and a computer medium. A temperature sensor is installed on the surface of the battery cell to detect the temperature of the battery cell; a temperature sensor is installed outside the energy storage system cabinet to monitor the external environmental temperature of the energy storage; the liquid cooling unit has the function of detecting the real-time temperature of the immersion liquid, and the temperature sensors on the surface of the battery cell should be evenly arranged to more accurately obtain the average value of each temperature. The immersion battery pack is filled with immersion liquid, which is connected in series and parallel with other battery packs through a liquid cooling circulation loop, and is connected to the liquid cooling unit, so that the immersion liquid that has passed through the liquid cooling unit for temperature control can exchange substances with the immersion liquid in the battery pack.

[0056] Among them, the liquid cooling unit has temperature sensors, refrigeration cycle heat exchange units, air direct cooling heat exchange units, heating units, water pumps and other components. The refrigeration cycle heat exchange unit includes a compressor, a water pump, an expansion valve, a heat exchanger and a cold row (cooling medium pipeline). The air direct cooling heat exchange unit includes a water pump and a heat exchanger. The heat exchanger includes a fan, that is, the immersion liquid pipeline connects two heat exchangers, one heat exchanger is a heat exchanger in the refrigeration cycle heat exchange unit, connected to the refrigeration cycle, and the other heat exchanger is connected to the fan for air direct cooling. The heating unit is used to heat the immersion liquid.

[0057] Among them, the temperature sensor can monitor the immersion liquid temperature at the inlet and outlet of the liquid cooling unit. The refrigeration cycle heat exchange unit uses a fan to make air exchange heat with the refrigeration phase change medium, and then makes the refrigeration phase change medium exchange heat with the immersion liquid to cool the immersion liquid; the air direct cooling heat exchange unit uses a fan to make air exchange heat with the cold row with immersion liquid flowing to cool the immersion liquid, and the water pump drives the immersion liquid to flow in the liquid cooling circulation loop. Among them, the refrigeration phase change medium can be Freon.

[0058] In another embodiment of the present application, an energy storage system is provided, such as Figure 3 As shown, it includes: a liquid cooling unit 100; a battery pack 200, which is connected to the liquid cooling unit 100 through a pipeline, and the liquid cooling unit 100 is used to cool the battery pack 200 through a coolant; an external water pump 300, which is installed on the main road between the liquid cooling unit 100 and the battery pack 200, and the external water pump 300 is used to increase the flow rate of the coolant; a controller 600, which is used to start the external water pump 300 when the coolant temperature is less than the coolant threshold temperature, so as to increase the flow rate of the coolant to a preset flow rate range, and to shut down the external water pump 300 when the coolant temperature is greater than or equal to the coolant threshold temperature.

[0059] The controller in the energy storage system is generally a battery management system (BMS) or an energy storage management system (ESM). In order to ensure that the liquid cooling system can maintain the rated flow rate under low temperature conditions and does not cause a decrease in temperature control ability, a water pump (external water pump) controlled by the battery management system is connected in series to the main pipeline of the liquid cooling circulation loop. When the coolant temperature is too low, the viscosity is high, or the system needs to operate at a cooling or heating power higher than the rated power, the water pump (external water pump) installed in the pipeline is turned on to meet the temperature control requirements of the system.

[0060] In some embodiments, the controller is further configured to execute the steps of the cooling cycle method described below.

[0061] The controller in the above energy storage system monitors the temperature of the battery pack in real time by receiving the signal collected by the temperature sensor. When the temperature of the battery pack is too high, the controller controls the liquid cooling unit and the coolant to cool the battery pack. The controller also monitors the temperature of the coolant in real time by receiving the signal collected by the temperature sensor. When the temperature of the coolant is too low, the controller controls the external water pump to start to increase the flow rate of the coolant.

[0062] The embodiment of the present application also provides a cooling liquid circulation method. The method embodiment provided in the embodiment of the present application can be executed in a mobile terminal, a computer terminal or a similar computing device. Taking running on a mobile terminal as an example, Figure 4FIG. 1 is a hardware structure block diagram of a mobile terminal of a cooling cycle method according to an embodiment of the present invention. Figure 4 As shown, the mobile terminal may include one or more ( Figure 4 Only one is shown in the figure) a processor 102 (the processor 102 may include but is not limited to a processing device such as a microprocessor MCU or a programmable logic device FPGA) and a memory 104 for storing data, wherein the mobile terminal may also include a transmission device 106 and an input / output device 108 for communication functions. It can be understood by those skilled in the art that Figure 4 The structure shown is only for illustration and does not limit the structure of the mobile terminal. Figure 4 More or fewer components as shown, or with Figure 4 Different configurations are shown.

[0063] The memory 104 can be used to store computer programs, for example, software programs and modules of application software, such as the computer program corresponding to the cooling cycle method in the embodiment of the present invention. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, that is, the above method is realized. The memory 104 may include a high-speed random access memory, and may also include a non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some examples, the memory 104 may further include a memory remotely arranged relative to the processor 102, and these remote memories can be connected to the mobile terminal via a network. Examples of the above-mentioned network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof. The transmission device 106 is used to receive or send data via a network. The above-mentioned specific examples of the network may include a wireless network provided by a communication provider of the mobile terminal. In one example, the transmission device 106 includes a network adapter (Network Interface Controller, referred to as NIC), which can be connected to other network devices through a base station so as to communicate with the Internet. In one example, the transmission device 106 may be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0064] In this embodiment, a cooling cycle method running on a mobile terminal, a computer terminal or a similar computing device is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0065] Figure 5is a flow chart of a cooling cycle method according to an embodiment of the present application. Figure 5 As shown, the method comprises the following steps:

[0066] Step S201, obtaining the coolant temperature;

[0067] Specifically, a coolant temperature sensor is installed in the energy storage system. By monitoring the data collected by the coolant temperature sensor, the real-time temperature of the coolant can be obtained, and the coolant temperature can be monitored in real time.

[0068] Step S202, when the coolant temperature is lower than the coolant threshold temperature, starting an external water pump to increase the flow rate of the coolant to a preset flow rate range, wherein the external water pump is installed on a main line between the liquid cooling unit and the battery pack;

[0069] Specifically, in an immersion liquid cooling system, a coolant (such as mineral oil, synthetic oil, or water-based coolant) is used to absorb and carry away the heat generated by the battery pack during the charging and discharging process. The viscosity of the coolant (i.e., flow resistance) usually increases as the temperature decreases. When the coolant temperature is lower than a preset threshold temperature (i.e., the coolant threshold temperature, such as -10°C, the specific value depends on the type of coolant and the system design), the viscosity of the coolant will increase significantly, which will increase the resistance of the liquid cooling circulation loop, reduce the flow rate of the coolant, and thus affect the cooling effect of the entire system. In order to overcome the decrease in coolant flow rate caused by low temperature, an external water pump is introduced into the system design. This water pump is different from the built-in water pump in the liquid cooling unit. It is installed on the main circuit of the liquid cooling circulation loop and is located between the liquid cooling unit and the battery pack. When the coolant temperature is detected to be lower than the coolant threshold temperature, the system controller (usually the battery management system BMS) will start the external water pump. Activation of the external water pump increases the driving force of the coolant, overcoming the additional resistance caused by increased viscosity, thereby increasing the flow rate of the coolant to a preset flow rate range that can ensure effective cooling.

[0070] In a liquid cooling system, the temperature of the coolant is a key parameter that directly affects the flow properties and heat exchange efficiency of the coolant. When the coolant temperature drops below the preset coolant threshold temperature, the viscosity of the coolant will increase significantly, which will increase the flow resistance of the liquid cooling system, thereby reducing the flow rate of the coolant. In order to overcome this situation, the system needs to adjust the speed of the external water pump to provide sufficient driving force to ensure that the coolant can still circulate within the preset flow rate range, thereby maintaining the cooling efficiency of the system. Wherein, when the above-mentioned coolant temperature is less than the coolant threshold temperature, starting the above-mentioned external water pump includes the following steps:

[0071] Step S2021, when the coolant temperature is less than the coolant threshold temperature, obtaining a first temperature difference and / or a target ratio, wherein the first temperature difference is a difference between the coolant temperature and the coolant threshold temperature, and the target ratio is a ratio of the coolant temperature to the coolant threshold temperature;

[0072] Step S2022, obtaining a first mapping relationship and a second mapping relationship, wherein the first mapping relationship represents a relationship between a difference between the temperature of the coolant and the coolant threshold temperature and a rotation speed of the external water pump, and the second mapping relationship represents a relationship between a ratio of the temperature of the coolant to the coolant threshold temperature and a rotation speed of the external water pump;

[0073] Step S2023, determining the target speed of the external water pump according to the first temperature difference and the first mapping relationship, and / or determining the target speed of the external water pump according to the target ratio and the second mapping relationship, and controlling the external water pump to operate at the target speed.

[0074] Specifically, if the first temperature difference is a positive number, it means that the coolant temperature is greater than the coolant threshold temperature and the external water pump is turned off. If the first temperature difference is a negative number, it means that the coolant temperature is less than the coolant threshold temperature and the external water pump is turned on. In the case where the first temperature difference is a negative number, the smaller the first temperature difference is, the further the coolant temperature is from its ideal operating temperature, and the stronger the response the system needs to make, that is, the faster the speed of the external water pump should be.

[0075] In some instances, the relationship between the absolute value of the first temperature difference and the rotation speed of the external water pump can also be used for judgment. Specifically, the rotation speed of the corresponding external water pump is determined according to the absolute value of the first temperature difference, and the absolute value of the first temperature difference is positively correlated with the rotation speed of the external water pump, that is, the larger the absolute value of the first temperature difference, the further the coolant temperature is from its ideal working temperature, and the greater the rotation speed of the external water pump should be. Among them, the absolute value of the temperature difference eliminates the influence of the positive and negative directions of the temperature difference, that is, the absolute value of the temperature difference at this time directly reflects the degree of deviation between the coolant temperature and the threshold temperature, which means that as long as the size (absolute value) of the temperature difference reaches or exceeds the preset value, the system will adjust the rotation speed accordingly. In addition, the use of the absolute value of the temperature difference can simplify the complexity of the control logic. It is only necessary to pay attention to whether the absolute value of the difference reaches the threshold value that requires increasing the coolant flow rate, and there is no need to distinguish the direction of the temperature difference.

[0076] The target ratio is related to the positive or negative value of the coolant temperature and the coolant threshold temperature. When the coolant temperature and the coolant threshold temperature are both positive, a target ratio of less than 1 indicates that the coolant temperature is lower than the threshold temperature, and the system needs to start or adjust the external water pump to increase the flow rate; a target ratio of greater than 1 indicates that the coolant temperature is above the threshold temperature, and the external water pump needs to be turned off. Similarly, the smaller the target ratio is, the further the coolant temperature is from its ideal operating temperature, and the stronger the response the system needs to make, that is, the faster the speed of the external water pump should be. When the coolant temperature and the coolant threshold temperature are both negative, a target ratio of less than 1 indicates that the coolant temperature is higher than the threshold temperature, and the system needs to turn off the external water pump; a target ratio of greater than 1 indicates that the coolant temperature is lower than the threshold temperature, and the external water pump needs to be started or adjusted to increase the flow rate. Similarly, the larger the target ratio is, the further the coolant temperature is from its ideal operating temperature, and the stronger the response the system needs to make, that is, the faster the speed of the external water pump should be.

[0077] In addition, in some embodiments, the ratio of the absolute value of the coolant temperature to the absolute value of the coolant threshold temperature may be used as a target ratio for determination.

[0078] The first mapping relationship and the second mapping relationship are both a mathematical relationship curve or a table. The first mapping relationship and the second mapping relationship are usually established through experimental data during the system design phase.

[0079] In some embodiments, the coolant threshold temperature (tc1) is set to -10°C. This temperature is set based on data that the viscosity of the coolant increases significantly below -10°C. The coolant threshold temperature is set differently for different types of coolants. The target flow rate range is set to 0.5 m / s to 1 m / s to ensure that the coolant can effectively exchange heat in the battery pack.

[0080] Among them, a data relationship table between the rotation speed and lift of an external water pump is shown in Table 1:

[0081] Table 1

[0082]

[0083] The specific first mapping relationship and the second mapping relationship need to be set according to the actual working conditions and the type of coolant. The coolant viscosity is determined according to the actual coolant temperature, the coolant resistance is determined according to the coolant viscosity, and the coolant resistance is equivalent to the external water pump head. Then, the speed of the external water pump is obtained according to Table 1.

[0084] When the system detects that the actual temperature of the coolant is -15°C (lower than tc1), the coolant temperature is 5°C lower than the threshold temperature, and the first temperature difference is -5°C. According to the first mapping relationship, the speed of the external water pump needs to be adjusted to 2500 RPM (revolutions per minute) to provide sufficient thrust to overcome the high viscosity caused by low temperature and ensure that the flow rate of the coolant is within the target range. At the same time, the target ratio is 1.5. According to the second mapping relationship, the speed of the external water pump needs to be adjusted to 3000 RPM to achieve the same effect.

[0085] In actual applications, the system may use both mappings at the same time, or select one of them according to different working conditions. For example, when the coolant temperature is significantly lower than the threshold temperature, it may rely more on the first mapping (temperature difference corresponds to speed), while when the temperature difference is not large, but the coolant temperature ratio is significantly higher than the threshold temperature, it may be more inclined to use the second mapping (target ratio corresponds to speed).

[0086] Through this intelligent control strategy, the system can dynamically respond to changes in coolant temperature and accurately adjust the water pump speed to ensure optimal cooling performance under various conditions. This is an important innovation in the design of immersion liquid-cooled energy storage systems, which helps to improve the overall efficiency of the system and the operating life of the battery.

[0087] Based on the above embodiment, it can be determined that the above coolant temperature is negatively correlated with the rotation speed of the above external water pump.

[0088] Specifically, when the coolant temperature is high, its viscosity is relatively low, and the flow resistance of the liquid cooling system is small. At this time, by reducing the speed of the external water pump, the energy consumption of the system can be reduced, while avoiding unnecessary excessive circulation, thereby optimizing the overall energy efficiency of the system. When the coolant temperature is low, its viscosity is relatively high, and the flow resistance of the liquid cooling system is large, which will increase the flow resistance of the liquid cooling system and affect the flow rate of the coolant. By increasing the speed of the external water pump, additional driving force can be provided to the system to overcome the resistance caused by the increased viscosity, ensuring that the flow rate of the coolant in the system remains at an effective level, thereby maintaining sufficient heat exchange efficiency.

[0089] The coolant temperature sensor may have abnormal parameters during the detection process, and when this happens, the external water pump may be mistakenly turned on or off, affecting the overall cooling of the system. Therefore, when the coolant temperature is lower than the coolant threshold temperature, the external water pump is started, and the following steps are also included:

[0090] Step S2024, when the coolant temperature is less than the coolant threshold temperature, obtaining a target temperature change rate of the coolant, where the target temperature change rate of the coolant is a change rate of the temperature of the coolant within a preset time period;

[0091] Step S2025, obtaining a third mapping relationship, wherein the third mapping relationship represents the relationship between the temperature change rate of the coolant and the rotation speed of the external water pump;

[0092] Step S2026, determining the target speed of the external water pump according to the target temperature change rate of the coolant and the third mapping relationship, and controlling the external water pump to operate at the target speed.

[0093] The above steps obtain the target temperature change rate of the coolant and use the third mapping relationship to determine and control the speed of the external water pump. The immersion liquid-cooled energy storage system can achieve intelligent and dynamic management of the coolant temperature, that is, it can more accurately reflect the changing pattern of the coolant temperature and will not be affected by instantaneous abnormal values. In some cases, it can also predict the temperature change trend of the coolant according to the target temperature change rate and control the speed of the external water pump in advance.

[0094] For example, if the target temperature change rate is 2°C per minute, the third mapping relationship may indicate that the speed of the external water pump needs to be adjusted to 3500 RPM to ensure that the coolant can be heated at this rate.

[0095] According to the target temperature change rate, the temperature change trend of the coolant is predicted, and the speed of the external water pump is controlled in advance. A variety of control algorithms can be used to achieve this, among which the more common and effective ones are PID control algorithm, fuzzy logic control algorithm and model predictive control algorithm (MPC). In the specific implementation, firstly, the temperature data of the coolant is continuously collected, and these data are analyzed by control units such as the battery management system (BMS) to calculate the change rate of the target temperature; then, the historical data and the current temperature change rate are used to predict the future change trend of the coolant temperature through algorithms (such as time series analysis, machine learning algorithms, etc.), and finally, based on the predicted coolant temperature change trend, the speed adjustment strategy of the external water pump is determined, and the water pump speed is adjusted dynamically in real time according to the target temperature change rate.

[0096] For example: if it is predicted that the coolant temperature will rise, the system will increase the water pump speed in advance to increase the coolant circulation rate and heat exchange efficiency; conversely, if it is predicted that the coolant temperature will drop, the water pump speed will be reduced accordingly to avoid unnecessary energy consumption and system wear.

[0097] Predictive control enables the system to adapt to temperature changes in advance, avoiding degradation of battery cell performance and safety risks caused by rapid temperature rise or fall, and enhancing system stability and reliability. By dynamically adjusting the speed of the external water pump, the system can more accurately control the temperature of the coolant, avoiding the temperature control lag problem that may occur in traditional control methods, and improving the control accuracy of the battery cell temperature.

[0098] In addition, the type of coolant is crucial to the performance of the liquid cooling system. Different coolants have different physical and chemical properties, such as thermal conductivity, specific heat capacity, viscosity, freezing point and chemical stability. In an immersion liquid-cooled energy storage system, water-based coolants, mineral oils, synthetic oils, fluorinated liquids (such as Novec) or silicone oils may be used. The system first needs to identify or obtain the type of coolant currently in use, which is the basis for subsequent threshold temperature determination. That is, the above method also includes the following steps:

[0099] Step S301, obtaining the type of the above-mentioned coolant;

[0100] Step S302, obtaining a fourth mapping relationship, wherein the fourth mapping relationship represents a relationship between the type of the coolant and a threshold temperature of the coolant;

[0101] Step S303: determining the coolant threshold temperature according to the type of the coolant and the fourth mapping relationship.

[0102] For example, for a mixture of water and ethylene glycol, the threshold temperature may be set to -35°C; for mineral oil, the threshold temperature may be between -18°C and -24°C; and for synthetic oil, the threshold temperature may be lower, such as below -40°C. The selection of specific values ​​of these threshold temperatures depends on the flow properties of the coolant at low temperatures and the specific design requirements of the liquid cooling system. Among them, the fourth mapping relationship is shown in Table 2:

[0103] Table 2

[0104]

[0105] Wherein, after starting the external water pump, the method further comprises the following steps:

[0106] Step S401, obtaining a water pump characteristic curve of the external water pump, the water pump characteristic curve characterizing the ability of the external water pump to increase the flow rate of the coolant, the water pump characteristic curve at least comprising a flow head curve of the external water pump, the flow head curve characterizing the relationship between the flow rate of the coolant and the head of the external water pump, the head of the external water pump being in direct proportion to the rotation speed of the external water pump;

[0107] Step S402 determines the rotation speed of the external water pump according to the water pump characteristic curve of the external water pump, the flow rate of the coolant and the preset flow rate range of the coolant.

[0108] Specifically, the water pump characteristic curve provides the relationship between the flow rate and head (i.e., the ability of the pump to overcome resistance and lift the liquid height) at different water pump speeds. This enables the system to accurately adjust the water pump speed according to the coolant flow demand, ensuring that the coolant circulates at the optimal speed and maintaining sufficient flow rate for heat exchange even when the coolant viscosity increases at low temperatures.

[0109] The following is a specific example to explain this process. Assume that the current coolant flow rate is 10 liters per minute (LPM). The system preset flow rate range is: minimum flow rate 20 LPM, maximum flow rate 30 LPM. The characteristic curve of the external water pump is given in the form of a flow head curve. The flow head curve is shown in Table 3:

[0110] Table 3

[0111]

[0112] In most water pumps, there is a positive proportional relationship between the head (H) and the speed (N), that is, in the above embodiment, when the speed of the water pump increases from 2000 RPM to 3500 RPM, the head increases from 10 meters to 25 meters, and the flow rate also increases from 10 LPM to 25 LPM. When the system detects that the coolant flow rate is 10 LPM, which is lower than the preset minimum flow rate of 20 LPM, it is necessary to increase the flow rate by adjusting the speed of the external water pump. According to the above flow head curve, when the flow rate is 20 LPM, the corresponding head is 20 meters and the speed is 3000 RPM.

[0113] When the system is running, assume that the coolant temperature drops to -10°C, causing the viscosity to increase. The original coolant flow rate is 10 LPM, which is lower than the system preset minimum flow rate of 20 LPM. The system controller reads the current coolant flow rate and adjusts the water pump speed to 3000 RPM with reference to the flow head curve of the external water pump. In this way, the water pump can provide sufficient head to overcome the flow resistance caused by the increase in coolant viscosity, thereby increasing the coolant flow rate to 20 LPM, reaching the system preset flow rate range and ensuring the cooling effect.

[0114] Wherein, after starting the external water pump, the method further comprises the following steps:

[0115] Step S501, obtaining the maximum pressure of the pipeline of the energy storage system and the maximum pressure of the liquid cooling unit;

[0116] Step S502, determining a maximum pressure threshold of the coolant according to the maximum pressure of the pipeline of the energy storage system and the maximum pressure of the liquid cooling unit;

[0117] Step S503, when the real-time pressure of the coolant reaches the maximum pressure threshold, determining that the current rotation speed of the external water pump reaches the maximum rotation speed.

[0118] For the pipeline, the maximum pressure may be 10 bar; for the liquid cooling unit, the maximum pressure may be 12 bar. The maximum pressure threshold should be determined by considering the minimum value of the maximum pressure of the pipeline and the liquid cooling unit to ensure that the entire system operates within a safe range. For example, if the maximum pressure of the pipeline is 10 bar and the maximum pressure of the liquid cooling unit is 12 bar, then the maximum pressure threshold of the coolant should be determined to be 10 bar.

[0119] When the real-time monitored pressure value approaches or reaches the maximum pressure threshold, the system controller should take immediate action to reduce or stop the speed of the external water pump to prevent the pressure from further increasing. The controller can dynamically adjust the water pump speed through PID algorithms, fuzzy logic control, or model predictive control to keep the pressure generated within a safe range. For example, suppose the current water pump speed is 3000 RPM and the coolant pressure is 9.5 bar, which is close to the maximum pressure threshold of 10 bar. The controller will send a signal to reduce the water pump speed to 2500 RPM until the pressure drops to a safe level, such as 9 bar.

[0120] To further ensure safety, the system can set up a pressure protection mechanism. When the coolant pressure exceeds the maximum pressure threshold, the external water pump is automatically shut down and an alarm is triggered to notify maintenance personnel to check whether there are any faults in the pipeline and liquid cooling unit.

[0121] In some instances, assuming that the maximum pressure of the pipeline is 10 bar, the maximum pressure of the liquid cooling unit is 12 bar, and the maximum pressure threshold of the coolant is determined to be 10 bar. During the operation of the system, the real-time monitoring of the coolant pressure is 9 bar. As the speed of the external water pump increases, the pressure gradually rises to 9.8 bar. At this time, the controller predicts through the PID control algorithm that if the water pump continues to run at the current speed, the coolant pressure is likely to exceed the maximum pressure threshold of 10 bar in a short time. Therefore, the controller immediately adjusts the speed of the external water pump, for example, reducing it to 2000 RPM, until the pressure stabilizes within a safe range below 10 bar. If the pressure detected by the pressure sensor exceeds 10 bar, the pressure protection mechanism will be activated, automatically shutting down the external water pump and triggering an alarm.

[0122] In summary, this technical means of real-time pressure monitoring and dynamic speed control can ensure that the liquid-cooled energy storage system automatically adjusts under high-pressure risks, avoiding pipeline rupture, pump damage or other safety problems caused by overpressure, thereby protecting the integrity and stability of the entire system.

[0123] Step S203: when the coolant temperature is greater than or equal to the coolant threshold temperature, turn off the external water pump.

[0124] Specifically, when the coolant temperature reaches or exceeds the preset threshold temperature, it means that the viscosity of the coolant has been reduced enough to circulate normally through the water pump inside the liquid cooling unit, and no additional external water pump is required to increase the flow rate. Turning off the external water pump can significantly reduce energy consumption because the operation of the external water pump consumes additional electricity. In large-scale energy storage applications, this energy-saving effect is particularly evident, helping to reduce operating costs. And when the external water pump runs at high speed, it will experience greater mechanical stress and wear. When the coolant temperature is high and the viscosity is low, the system no longer needs the high flow rate enhancement of the external water pump. Turning it off can reduce unnecessary mechanical wear, extend the service life of the pump, and reduce maintenance frequency.

[0125] Wherein, the energy storage system further includes a first three-way valve and a second three-way valve, and the method further includes the following steps:

[0126] Step S601, when the coolant temperature is lower than the coolant threshold temperature, the external water pump is connected to the main circuit between the liquid cooling unit and the battery pack through the first three-way valve and the second three-way valve;

[0127] Step S602, when the coolant temperature is greater than or equal to the coolant threshold temperature, the liquid cooling unit is connected to the battery pack through the first three-way valve and the second three-way valve through a branch pipeline, and the external water pump is short-circuited.

[0128] Specifically, when the coolant temperature is low and the viscosity increases, the start-up of the external water pump can significantly increase the flow rate of the coolant, thereby overcoming the flow resistance caused by the increased viscosity, ensuring that the coolant circulates effectively between the battery pack and the liquid cooling unit, maintaining the temperature of the battery cell within a safe and efficient range, and avoiding performance degradation due to low temperature. When the coolant temperature rises to the threshold temperature or above, the external water pump is turned off, and the liquid cooling unit and the battery pack are directly connected through a branch pipeline to reduce additional energy consumption. The external water pump is necessary in high viscosity conditions, but when the viscosity is low, the water pump inside the liquid cooling unit is sufficient to maintain the circulation of the coolant. The shutdown of the external water pump helps to improve the overall energy efficiency of the system. In addition, frequent starting and high-load operation of the external water pump will accelerate its wear and affect its service life. When the flow rate does not need to be increased, short-circuiting the external water pump through a three-way valve can reduce its operating time, effectively extend the service life of the water pump, and reduce maintenance and replacement costs.

[0129] The above method further comprises the following steps:

[0130] Step S701, obtaining the cell temperature of each of the above battery packs;

[0131] Step S702, obtaining a low-temperature threshold temperature of the battery cell and a high-temperature threshold temperature of the battery cell;

[0132] Step S703, when the highest battery cell temperature is lower than the battery cell low temperature threshold temperature, controlling the energy storage system to be in a heating mode, wherein the heating mode is a mode for heating the coolant;

[0133] Step S704, when the lowest battery cell temperature is greater than the battery cell high temperature threshold temperature, controlling the energy storage system to be in a cooling mode, wherein the cooling mode is a mode for cooling the coolant;

[0134] Wherein, controlling the energy storage system to be in cooling mode comprises the following steps:

[0135] Step S7041, obtaining the ambient temperature of the energy storage system.

[0136] Step S7042, determining the difference between the ambient temperature and the coolant temperature as a second temperature difference;

[0137] Step S7043, when the second temperature difference is less than the preset temperature difference, the coolant is cooled by air direct cooling, where the air direct cooling is a mode of cooling the coolant by ambient air;

[0138] Step S7044, when the second temperature difference is greater than or equal to the preset temperature difference, a refrigeration cycle mode is used to cool the coolant, and the refrigeration cycle mode is a mode of cooling the coolant by using a refrigeration phase change medium.

[0139] Specifically, when the difference between the ambient temperature and the coolant temperature is less than the preset temperature difference, the system adopts the air direct cooling mode, using the ambient air to naturally cool the coolant instead of starting the refrigeration phase change medium cycle, which can greatly save energy when the ambient temperature is suitable and improve the energy efficiency of the system. The equipment and components involved in the refrigeration cycle mode are more complex, including refrigerators, phase change media, etc. By intelligently switching the cooling mode, the use of the refrigeration cycle mode can be reduced when the ambient temperature is suitable, thereby reducing the wear and maintenance frequency of the refrigeration equipment and simplifying the system maintenance work.

[0140] Assuming that the preset temperature difference is 5°C, the current ambient temperature is 20°C, and the coolant temperature is 25°C, then the second temperature difference is 5°C, which is exactly equal to the preset temperature difference. In this case, the system will select the refrigeration cycle mode because the ambient temperature is not high enough to effectively cool the coolant above 25°C. The refrigeration cycle mode will start, using the refrigeration phase change medium to cool the coolant until the coolant temperature drops closer to the ambient temperature, so that the second temperature difference is less than the preset value, the system will automatically switch to the more energy-saving air direct cooling mode and use the ambient air for cooling. Conversely, if the ambient temperature is 15°C, the coolant temperature is 20°C, and the second temperature difference is 5°C, which is less than the preset temperature difference, the system will start the air direct cooling mode and use the natural cooling capacity of the ambient air to cool the coolant, avoiding unnecessary energy consumption and the use of refrigeration phase change media, and achieving the purpose of energy saving and emission reduction.

[0141] Through this temperature difference-based cooling mode selection mechanism, the liquid-cooled energy storage system can intelligently adjust its cooling strategy to ensure that the battery cell temperature is controlled within the optimal operating range, while taking into account energy efficiency and cost control, to achieve efficient, safe and environmentally friendly operation goals.

[0142] Step S705, when the highest battery cell temperature is greater than or equal to the battery cell low temperature threshold temperature, and the lowest battery cell temperature is less than or equal to the battery cell high temperature threshold temperature, control the energy storage system to a self-circulation mode, wherein the self-circulation mode is a mode in which the coolant is not cooled or heated.

[0143] Specifically, by acquiring the cell temperature of each battery pack in real time and comparing it with the preset cell low temperature threshold temperature and cell high temperature threshold temperature, the system can respond to temperature changes in a timely manner and adopt heating, cooling or self-circulation mode to prevent the cell temperature from exceeding the safe and efficient working range, thereby achieving precise control of the cell temperature. If the cell works at too low or too high a temperature, its internal resistance will increase and the charging and discharging efficiency will decrease. Being in this state for a long time will accelerate the aging of the cell. Through the above control strategy, the cell temperature can be effectively maintained in the ideal range, thereby extending the service life of the cell and reducing maintenance and replacement costs.

[0144] The above-mentioned cooling cycle method of the present application first obtains the coolant temperature; then, when the coolant temperature is less than the coolant threshold temperature, starts the external water pump to increase the flow rate of the coolant to a preset flow rate range, wherein the external water pump is installed on the main line between the liquid cooling unit and the battery pack; finally, when the coolant temperature is greater than or equal to the coolant threshold temperature, turns off the external water pump. When the coolant temperature is lower than the threshold, that is, the coolant viscosity is too large, the coolant flow rate slows down, resulting in poor cooling effect, this method increases the coolant flow rate by turning on the external water pump between the liquid cooling unit and the battery pack, so that the coolant flow rate can be kept within the flow rate range required for cooling, maintaining the cooling effect, and solving the problem in the prior art that the viscosity of the immersion liquid increases and the flow rate decreases under low temperature conditions, resulting in reduced cooling effect.

[0145] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the implementation process of the cooling cycle method of the present application will be described in detail below in conjunction with specific embodiments.

[0146] The liquid cooling unit has three working modes, namely, a refrigeration cycle mode in which the refrigeration cycle heat exchange unit works alone, an air direct cooling mode in which the air direct cooling heat exchange unit works alone, a heating mode in which the heating unit works alone, and a self-circulation mode in which none of the three units works and only the water pump works.

[0147] Among them, the external water pump is installed on the main pipeline in series with the liquid cooling unit, and another pipeline is connected in parallel with the water pump using a three-way solenoid valve. The state of the three-way solenoid valve is controlled by a computer medium, and the start and stop of the external water pump can be controlled by the computer medium. The water pump shut-off operation mentioned later is to shut off the water pump and change the connection state of the three-way valve, so that the immersion liquid flows through the pipeline parallel to the water pump.

[0148] Among them, the computer medium in the energy storage system can read the surface temperature of the battery cells in the system and the inlet and outlet temperatures of the immersion liquid read by the liquid cooling unit in real time, and control the start and stop of each three-way solenoid valve in the energy storage system, the start and stop of the liquid cooling unit, the start and stop of the external water pump, and the start and stop of the fan structure in the refrigerator.

[0149] In some embodiments, the cell low temperature threshold temperature t1, cell high temperature threshold temperature t2, environment threshold temperature te1, and coolant threshold temperature tc1 are pre-introduced into the computer medium. When the detected cell maximum temperature is lower than the cell low temperature threshold temperature t1, the system needs to be heated; when the detected cell minimum temperature is higher than the cell low temperature threshold temperature t2, the system needs to be cooled, and the self-circulation mode is turned on in other cases. The recommended value of t1 is about 15°C, and the recommended value of t2 is about 26°C. When the ambient temperature is lower than the immersion liquid temperature -5, the immersion liquid can be cooled by direct air cooling. When the ambient temperature is greater than the immersion liquid temperature -5, the immersion liquid needs to be cooled by a refrigeration cycle. When the immersion liquid temperature is lower than tc1, the immersion liquid viscosity is large, and an external water pump needs to be started; when the immersion liquid temperature is lower than tc1, the immersion liquid viscosity is small, and the external water pump can be turned off. The value of tc1 depends on the type of immersion liquid selected.

[0150] This embodiment relates to a specific cooling cycle method, such as Figure 6 As shown, first read the ambient temperature, battery cell temperature, and liquid cooler inlet water temperature to determine whether the highest battery cell temperature th is less than t1. If the highest battery cell temperature th is less than t1, no charging or discharging is performed, the liquid cooler is in heating mode, and the external water pump is turned off; if the highest battery cell temperature th is greater than or equal to t1, charging and discharging are turned on; then determine whether the lowest battery cell temperature is greater than t2. When the lowest battery cell temperature is greater than t2, determine whether the ambient temperature is less than the coolant temperature -5°C. When the ambient temperature is less than the coolant temperature -5°C, determine that the liquid cooling unit is in air cooling mode. When the ambient temperature is greater than or equal to the coolant temperature -5°C, determine that the liquid cooling unit is in refrigeration cycle mode. When the lowest battery cell temperature is less than or equal to t2, control the liquid cooling unit to self-circulation mode; finally, determine whether the coolant temperature is less than tc1. When the coolant temperature is less than tc1, start the external water pump. When the coolant temperature is greater than or equal to tc1, turn off the external water pump.

[0151] An embodiment of the present application also provides an energy storage system, including a controller, wherein the controller is used to execute any cooling cycle method.

[0152] The present application also provides a controller. It should be noted that the controller of the present application can be used to execute the cooling cycle method provided by the present application. The controller is used to implement the above embodiments and preferred implementations, and the descriptions that have been made will not be repeated.

[0153] The controller includes a processor and a memory, and the processor executes the program unit stored in the memory to implement the corresponding functions. The modules are all located in the same processor; or, the modules are located in different processors in any combination.

[0154] The processor includes a kernel, which retrieves the corresponding program unit from the memory. One or more kernels can be set, and the problem of the immersion liquid in the prior art that the viscosity increases and the flow rate decreases under low temperature conditions, resulting in reduced cooling effect, can be solved by adjusting kernel parameters.

[0155] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0156] An embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium includes a stored program, wherein when the program is executed, the device where the computer-readable storage medium is located is controlled to execute the cooling cycle method.

[0157] An embodiment of the present invention provides a processor, and the processor is used to run a program, wherein the cooling cycle method is executed when the program is run.

[0158] An embodiment of the present invention provides a device, the device includes a processor, a memory, and a program stored in the memory and executable on the processor, and the processor implements at least the steps of the cooling cycle method when executing the program. The device in this article can be a server, a PC, a PAD, a mobile phone, etc.

[0159] The present application also provides a computer program product which, when executed on a data processing device, is adapted to execute a program for initiating at least the steps of the cooling cycle method.

[0160] Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, and in some cases, the steps shown or described can be executed in a different order than here, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. Thus, the present invention is not limited to any specific combination of hardware and software.

[0161] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0162] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0163] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0164] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0165] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0166] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0167] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0168] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity 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, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0169] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0170] 1) The above cooling cycle method of the present application first obtains the coolant temperature; then, when the coolant temperature is less than the coolant threshold temperature, starts the external water pump to increase the flow rate of the coolant to a preset flow rate range, wherein the external water pump is installed on the main line between the liquid cooling unit and the battery pack; finally, when the coolant temperature is greater than or equal to the coolant threshold temperature, turns off the external water pump. When the coolant temperature is lower than the threshold, that is, the coolant viscosity is too high, the coolant flow rate slows down, resulting in poor cooling effect, this method increases the coolant flow rate by turning on the external water pump between the liquid cooling unit and the battery pack, so that the coolant flow rate can be kept within the flow rate range required for cooling, maintaining the cooling effect, and solving the problem in the prior art that the viscosity of the immersion liquid increases and the flow rate decreases under low temperature conditions, resulting in reduced cooling effect.

[0171] 2) The energy storage system of the present application controls an external water pump installed on the main line between the liquid cooling unit and the battery pack to increase the flow rate of the coolant when the flow rate of the coolant decreases, so that the flow rate of the coolant remains within the required flow rate range for cooling, thereby ensuring the cooling requirements of the battery pack.

[0172] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A cooling cycle method for use in an energy storage system, characterized in that: The method comprises: Get coolant temperature; When the coolant temperature is lower than the coolant threshold temperature, an external water pump is started to increase the flow rate of the coolant to a preset flow rate range, wherein the external water pump is installed on a main line between the liquid cooling unit and the battery pack; When the coolant temperature is greater than or equal to the coolant threshold temperature, the external water pump is turned off.

2. The method according to claim 1, characterized in that After starting the external water pump, the method further includes: Obtaining a water pump characteristic curve of the external water pump, wherein the water pump characteristic curve represents the ability of the external water pump to increase the flow rate of the coolant, and the water pump characteristic curve at least includes a flow head curve of the external water pump, wherein the flow head curve represents the relationship between the flow rate of the coolant and the head of the external water pump, and the head of the external water pump is in direct proportion to the rotation speed of the external water pump; The rotation speed of the external water pump is determined according to a water pump characteristic curve of the external water pump, the flow rate of the coolant and a preset flow rate range of the coolant.

3. The method according to claim 1, characterized in that After starting the external water pump, the method further includes: Obtaining the maximum pressure that the pipeline of the energy storage system can withstand and the maximum pressure that the liquid cooling unit can withstand; Determining a maximum pressure threshold of the coolant according to a maximum pressure of the pipeline of the energy storage system and a maximum pressure of the liquid cooling unit; When the real-time pressure of the coolant reaches the maximum pressure threshold, it is determined that the current rotation speed of the external water pump reaches the maximum rotation speed.

4. The method according to claim 1, characterized in that: The method further comprises: Obtaining the type of the coolant; Acquire a fourth mapping relationship, where the fourth mapping relationship represents a relationship between the type of the coolant and a threshold temperature of the coolant; The coolant threshold temperature is determined according to the type of the coolant and the fourth mapping relationship.

5. The method according to claim 1, characterized in that When the coolant temperature is lower than the coolant threshold temperature, starting the external water pump comprises: When the coolant temperature is less than the coolant threshold temperature, obtaining a first temperature difference and / or a target ratio, wherein the first temperature difference is a difference between the coolant temperature and the coolant threshold temperature, and the target ratio is a ratio of the coolant temperature to the coolant threshold temperature; Acquire a first mapping relationship and a second mapping relationship, wherein the first mapping relationship represents a relationship between a difference between the temperature of the coolant and the coolant threshold temperature and a rotation speed of the external water pump, and the second mapping relationship represents a relationship between a ratio of the temperature of the coolant to the coolant threshold temperature and a rotation speed of the external water pump; The target speed of the external water pump is determined according to the first temperature difference and the first mapping relationship, and / or the target speed of the external water pump is determined according to the target ratio and the second mapping relationship, and the external water pump is controlled to operate at the target speed.

6. The method according to claim 1, characterized in that When the coolant temperature is lower than the coolant threshold temperature, starting the external water pump comprises: When the coolant temperature is less than the coolant threshold temperature, obtaining a target temperature change rate of the coolant, where the target temperature change rate of the coolant is a change rate of the coolant temperature within a preset time period; Acquire a third mapping relationship, wherein the third mapping relationship represents a relationship between a temperature change rate of the coolant and a rotation speed of the external water pump; The target speed of the external water pump is determined according to the target temperature change rate of the coolant and the third mapping relationship, and the external water pump is controlled to operate at the target speed.

7. The method according to claim 1, characterized in that The energy storage system further includes a first three-way valve and a second three-way valve, and the method further includes: When the coolant temperature is lower than the coolant threshold temperature, the external water pump is connected to the main circuit between the liquid cooling unit and the battery pack through the first three-way valve and the second three-way valve; When the coolant temperature is greater than or equal to the coolant threshold temperature, the liquid cooling unit and the battery pack are connected through the first three-way valve and the second three-way valve through a branch pipeline, and the external water pump is short-circuited.

8. The method according to claim 1, characterized in that There are multiple battery packs, and the method further includes: Obtaining the battery cell temperature of each battery pack; Get the low temperature threshold temperature and high temperature threshold temperature of the battery cell; When the highest battery cell temperature is lower than the battery cell low temperature threshold temperature, controlling the energy storage system to be in a heating mode, wherein the heating mode is a mode for heating the coolant; When the lowest battery cell temperature is greater than the battery cell high temperature threshold temperature, controlling the energy storage system to be in a cooling mode, wherein the cooling mode is a mode for cooling the coolant; When the highest battery cell temperature is greater than or equal to the battery cell low temperature threshold temperature, and the lowest battery cell temperature is less than or equal to the battery cell high temperature threshold temperature, the energy storage system is controlled to be in a self-circulation mode, and the self-circulation mode is a mode in which the coolant is not cooled or heated.

9. An energy storage system, characterized in that: include: Liquid cooling unit; A battery pack is connected to the liquid cooling unit through a pipeline, and the liquid cooling unit is used to cool the battery pack through a coolant; An external water pump is installed on a main line between the liquid cooling unit and the battery pack, and is used to increase the flow rate of the coolant.

10. The energy storage system according to claim 9, characterized in that: The liquid cooling unit has a liquid outlet and a liquid return port, and the liquid outlet is connected to the liquid outlet pipe, and the liquid return port is connected to the liquid return pipe. There are multiple battery packs, and one battery pack includes at least one battery cell. One end of the battery pack is connected to the liquid outlet pipe, and the other end of the battery pack is connected to the liquid return pipe. The liquid cooling unit is used to provide cooling liquid to each battery cell through the liquid outlet, and is also used to recover the cooling liquid in each battery cell through the liquid return port. The energy storage system also includes: a first three-way valve, having an inlet, an outlet and a bypass port, wherein the inlet of the first three-way valve is connected to the battery pack through a pipeline, the outlet of the first three-way valve is connected to the external water pump through a pipeline, and the bypass port of the first three-way valve is connected to a branch pipeline; a second three-way valve having an inlet, an outlet and a bypass port, wherein the inlet of the second three-way valve is connected to the external water pump through a pipeline, the outlet of the first three-way valve is connected to the liquid cooling unit through a pipeline, and the bypass port of the first three-way valve is connected to the branch pipeline; A plurality of valves are provided, each of the valves being installed on a pipeline between the corresponding battery pack and the liquid outlet pipe, and the valves correspond to the battery packs one by one.

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