Thermal management methods for energy storage systems, energy storage systems and electrical equipment

Abstract

This application relates to the field of energy storage technology, and discloses a thermal management method, energy storage system, and electrical equipment for an energy storage system. The thermal management method for the energy storage system includes: detecting the temperature of each cell within the battery pack; if the temperature of a cell is lower than a preset temperature threshold, controlling the fluid circulation loop to deliver working fluid to a temperature control structure to heat the cell; determining whether the temperature difference between different locations of the cell exceeds a preset temperature difference threshold; if the maximum temperature difference between two locations of the cell exceeds the preset temperature difference threshold, controlling the fluid circulation loop to stop delivering working fluid to the temperature control structure until the maximum temperature difference between the two locations of the cell is lower than the preset temperature difference threshold, and then controlling the fluid circulation loop to resume delivering working fluid to the temperature control structure. The thermal management method, energy storage system, and electrical equipment for the energy storage system provided in this application can help avoid affecting the performance of the battery cells.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a thermal management method for an energy storage system, an energy storage system, and electrical equipment. Background Technology

[0002] With the continuous development of new energy technologies, energy storage systems are being used more and more widely. Energy storage systems can store electrical energy and output it to the outside world when needed. Energy storage systems typically use individual battery cells as the basic energy storage unit. These cells have charge-discharge cycle characteristics, enabling them to switch between charging and discharging states. Energy storage systems utilize battery devices formed by these cells to achieve the storage and utilization of electrical energy.

[0003] The battery cells in an energy storage system operate within a suitable temperature range during charging and discharging, allowing them to perform optimally. However, excessively high or low temperatures can negatively impact cell performance. Therefore, effective thermal management of energy storage systems to prevent these adverse effects is a crucial issue. Summary of the Invention

[0004] The purpose of this application is to provide a thermal management method for an energy storage system, an energy storage system, and electrical equipment, which can help avoid affecting the performance of the battery cells.

[0005] To address the aforementioned technical problems, this application provides a thermal management method for an energy storage system. The energy storage system includes multiple battery packs and a fluid circulation loop. Each battery pack has multiple battery cells and a temperature control structure for regulating the temperature of the multiple battery cells. The fluid circulation loop is used to deliver a working fluid to the temperature control structure to heat or cool the battery cells. The thermal management method for the energy storage system includes: detecting the temperature of each battery cell within the battery pack; if the temperature of a battery cell is lower than a preset temperature threshold, controlling the fluid circulation loop to deliver a working fluid to the temperature control structure to heat the battery cell; determining whether the temperature difference between different locations of a battery cell exceeds a preset temperature difference threshold; if the maximum temperature difference between two locations of a battery cell exceeds the preset temperature difference threshold, controlling the fluid circulation loop to stop delivering a working fluid to the temperature control structure until the maximum temperature difference between two locations of a battery cell is lower than the preset temperature difference threshold, then controlling the fluid circulation loop to resume delivering a working fluid to the temperature control structure; and controlling the fluid circulation loop to stop delivering a working fluid to the temperature control structure when the temperature of each battery cell is not lower than the preset temperature threshold.

[0006] The embodiments of this application also provide an energy storage system, which includes multiple battery packs and a fluid circulation loop. The battery packs have multiple battery cells and a temperature control structure for regulating the temperature of the multiple battery cells. The fluid circulation loop is used to deliver working fluid to the temperature control structure to heat or cool the battery cells. The energy storage system also includes a battery management system, which is used to: detect the temperature of each battery cell in the battery pack; if the temperature of the battery cell is lower than a preset temperature threshold, control the fluid circulation loop to deliver working fluid to the temperature control structure to heat the battery cell; determine whether the temperature difference at different locations of the battery cell exceeds a preset temperature difference threshold; if the maximum temperature difference between two locations of the battery cell exceeds the preset temperature difference threshold, control the fluid circulation loop to stop delivering working fluid to the temperature control structure until the maximum temperature difference between the two locations of the battery cell is lower than the preset temperature difference threshold, and then control the fluid circulation loop to resume delivering working fluid to the temperature control structure; when the temperature of each battery cell is not lower than the preset temperature threshold, control the fluid circulation loop to stop delivering working fluid to the temperature control structure.

[0007] The embodiments of this application also provide an electrical device, which includes the energy storage system described above.

[0008] The thermal management method, energy storage system, and electrical equipment provided in this application heat the battery cells when the cell temperature is below a preset temperature threshold. This is achieved by controlling a fluid circulation loop to deliver working fluid to the temperature control structure in the battery pack, utilizing the heat of the working fluid to heat the cells. During the heating process, the system determines whether the temperature difference between different locations within the cell exceeds a preset temperature difference threshold. If the maximum temperature difference between two locations exceeds this threshold, the fluid circulation loop stops delivering working fluid to the temperature control structure until the maximum temperature difference between the two locations falls below the preset temperature difference threshold. Ultimately, the temperature of each cell reaches or exceeds the preset temperature threshold. This process controls the temperature difference between different locations within the cell during heating, preventing large temperature differences at the start of charging and discharging, thus avoiding any impact on the cell's performance.

[0009] In some implementations, after determining whether the temperature difference between different locations of the battery cell exceeds a preset temperature difference threshold, the method further includes: obtaining the average temperature of multiple battery cells in the battery pack and the average temperature of multiple battery cells in the energy storage system; determining whether the average temperature of multiple battery cells in the battery pack is higher than the average temperature of multiple battery cells in the energy storage system; if the average temperature of multiple battery cells in the battery pack is higher than the average temperature of multiple battery cells in the energy storage system, then controlling the fluid circulation loop to stop supplying working fluid to the temperature control structure.

[0010] In some embodiments, multiple battery packs form a battery cluster in a preset number. After determining whether the temperature difference between different positions of the battery cells exceeds a preset temperature difference threshold, the method further includes: obtaining the average temperature of multiple battery cells in the battery cluster and the average temperature of multiple battery cells in the energy storage system; determining whether the average temperature of multiple battery packs in the battery cluster is higher than the average temperature of multiple battery cells in the energy storage system; if the average temperature of multiple battery packs in the battery cluster is higher than the average temperature of multiple battery cells in the energy storage system, then controlling the fluid circulation loop to stop supplying working fluid to the temperature control structure of the battery packs in the battery cluster.

[0011] In some embodiments, multiple battery packs form a battery cluster in a preset number. During the heating process of the battery cells, the method further includes: obtaining the temperature of different battery packs in the battery cluster, wherein the temperature of the battery pack is the average temperature of multiple battery cells in the battery pack; determining whether the temperature difference between different battery packs in the battery cluster is higher than a preset temperature difference value; if the maximum temperature difference between two battery packs in the battery cluster is higher than the preset temperature difference value, then controlling the fluid circulation loop to stop supplying working fluid to the temperature control structure of the battery packs in the battery cluster.

[0012] In some embodiments, after the control fluid circulation loop stops supplying working fluid to the temperature control structure of the battery pack in the battery cluster, the method further includes: determining whether the temperature difference between two battery packs in the battery cluster is lower than a preset temperature difference value; if the temperature difference between two battery packs in the battery cluster is lower than the preset temperature difference value, then determining again whether the temperature difference between different battery packs in the battery cluster is higher than the preset temperature difference value.

[0013] In some embodiments, the energy storage system further includes a water pump located on the fluid circulation loop, the water pump being configured corresponding to the battery cluster. After controlling the fluid circulation loop to stop supplying working fluid to the temperature control structure of the battery pack within the battery cluster, the system further includes: connecting the temperature control structures in the two battery packs with the largest temperature difference to both ends of the water pump; and turning on the water pump to allow the working fluid to circulate within the temperature control structures of the two battery packs with the largest temperature difference.

[0014] In some implementations, after the water pump is turned on, the method further includes: determining whether the water pump's operating time exceeds a preset time; if the water pump's operating time exceeds the preset time, turning off the water pump and controlling the fluid circulation loop to re-supply the working fluid to the temperature control structure of the battery pack within the battery cluster.

[0015] In some embodiments, the fluid input ends of the temperature control structures of multiple battery packs in the battery cluster are interconnected, and the fluid output ends of the temperature control structures of multiple battery packs in the battery cluster are interconnected; the energy storage system includes a first solenoid valve and a second solenoid valve corresponding to the battery cluster, and a third solenoid valve corresponding to the battery pack. The first solenoid valve is located at the fluid input end of the temperature control structure of multiple battery packs in the battery cluster, the second solenoid valve is located at the fluid output end of the temperature control structure of multiple battery packs in the battery cluster, and the third solenoid valve is located between the first solenoid valve and the fluid input end of the temperature control structure.

[0016] In some embodiments, connecting the temperature control structures of the two battery packs with the greatest temperature difference to both ends of the water pump includes: connecting the water pump to the temperature control structures of any two battery packs in the battery cluster; closing the first solenoid valve and the second solenoid valve; and closing the third solenoid valve connected to the temperature control structures of the battery packs other than the two battery packs with the greatest temperature difference.

[0017] In some embodiments, at least some of the cells in the battery pack have multiple temperature sensors arranged sequentially in the height direction.

[0018] In some implementations, the preset temperature difference threshold is greater than or equal to 3°C. Attached Figure Description

[0019] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0020] Figure 1 This is a flowchart of a thermal management method for an energy storage system provided in some embodiments of this application;

[0021] Figure 2 This is a schematic diagram showing the temperature changes at different locations of the battery cell during the thermal management process, provided in some embodiments of this application.

[0022] Figure 3 This is a flowchart of the cell temperature control process for an energy storage system provided in some embodiments of this application;

[0023] Figure 4 This is a schematic diagram of the structure of the fluid circulation loop in the energy storage system provided in some embodiments of this application;

[0024] Figure 5 This is a schematic diagram of the distribution structure of solenoid valves in the fluid circuit of a battery cluster in an energy storage system provided in some embodiments of this application;

[0025] Figure 6This is a flowchart of cluster-level temperature control in an energy storage system provided in some embodiments of this application.

[0026] Reference numerals: 10, battery pack; 20, liquid cooling unit; 100, battery cluster; 101, first solenoid valve; 102, second solenoid valve; 103, third solenoid valve; 104, water pump. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the various embodiments of this application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been presented in the various embodiments of this application to enable readers to better understand this application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in this application can be implemented. The division of the various embodiments below is for the convenience of description and should not constitute any limitation on the specific implementation of this application. The various embodiments can be combined with and referenced by each other without contradiction.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0029] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0030] The proper functioning of an energy storage system relies heavily on temperature control. Under suitable temperature conditions, the battery cells in the system can better utilize their characteristics and enter an optimal charging and discharging state. Conversely, excessively high or low cell temperatures will adversely affect charging and discharging. During operation, the battery cells in the energy storage system generate heat, causing their temperature to rise. If this temperature is not controlled, it can lead to reduced cell efficiency, shortened lifespan, and even thermal runaway. Since natural heat dissipation cannot maintain the temperature within a suitable range, energy storage systems incorporate cooling systems to dissipate the heat generated during operation.

[0031] In reality, energy storage systems face highly variable external environments, and the temperature of the battery cells within these systems is also affected by these conditions. When the ambient temperature is low, the cell temperature can become excessively low. Charging and discharging under these conditions can lead to lithium plating, reducing cell lifespan, system stability, and safety. Therefore, energy storage systems, in addition to cooling, are also equipped with heating functions to raise the temperature of the low-temperature cells, ensuring they reach their operating temperature range and remain within the required range for normal operation.

[0032] During the charging and discharging process of the battery cell, heat transfer occurs from bottom to top as the working fluid flows through the cold plate for heating or cooling. This results in temperature differences between different locations within the individual battery cell. These temperature differences lead to uneven internal reactions within the cell, reduced performance, and consequently, the overall lifespan of the energy storage system. Therefore, ensuring temperature uniformity across different locations within the battery cell is crucial when heating or cooling it.

[0033] Currently, during the heating process of low-temperature battery cells in energy storage systems, the significant temperature difference between the heating liquid, the battery cell temperature, and the ambient temperature results in large temperature variations at different locations within the battery cell, severely impacting the overall lifespan of the energy storage system.

[0034] To minimize the temperature difference between different locations of cryogenic battery cells in an energy storage system after heating, some embodiments of this application provide a thermal management method used during the heating of cryogenic battery cells. After a battery cell has been heated for a period of time, when the temperature difference between different locations of a single battery cell reaches a threshold, heating is stopped until the temperature difference between different locations of the battery cell decreases below the threshold. Heating is then resumed, and this process is repeated until all battery cells in the energy storage system reach their operating temperature. Finally, the heating process is stopped, and the battery cells begin charging and discharging. By controlling the heating process, overall temperature uniformity of the battery cells throughout the energy storage system is achieved. The thermal management method provided in some embodiments of this application can solve the problem of excessive temperature differences between different locations of the battery cell after reaching the target temperature when both the ambient temperature and the battery cell temperature are low, and when using a liquid cooling unit to supply a high-temperature fluid to heat the battery cell.

[0035] The following is combined Figure 1 This application describes a thermal management method for an energy storage system provided in some embodiments. The energy storage system includes multiple battery packs and a fluid circulation loop. Each battery pack has multiple battery cells and a temperature control structure for regulating the temperature of the battery cells. The fluid circulation loop is used to deliver a working fluid to the temperature control structure to heat or cool the battery cells. Figure 4 and Figure 5 A schematic diagram of the fluid circulation loop in the energy storage system is provided.

[0036] like Figure 1 As shown, the thermal management method for an energy storage system provided in some embodiments of this application includes the following steps:

[0037] Step S110: Detect the temperature of each cell in the battery pack. If the temperature of the cell is lower than the preset temperature threshold, control the fluid circulation loop to deliver working fluid to the temperature control structure to heat the cell.

[0038] The battery pack 10 is a complete and independent energy storage unit within the energy storage system. Multiple cells within the battery pack 10 can be connected in series or parallel. The battery pack 10 also includes a temperature control structure, such as a cold plate or cold pipe, for controlling the temperature of the cells. This temperature control structure can be connected to the fluid circulation loop in the energy storage system, allowing heating or cooling liquids to enter and thus heat or cool the cells. The battery pack 10 also includes temperature sensors that detect the temperature at different locations within the cells. These temperature sensors can be positioned at any area of ​​the cell, such as the top, middle, or bottom.

[0039] Before charging and discharging, the temperature of the cells in battery pack 10 is monitored. At this time, the cell temperature is affected by the external environment; when the ambient temperature is low, the cell temperature will also be low, potentially falling below a preset temperature threshold. The preset temperature threshold is the minimum operating temperature required for the cell. By setting this minimum operating temperature, charging and discharging at low temperatures can be avoided, thus preventing any impact on the cell's performance.

[0040] When the cell temperature is low, a working fluid is supplied to the temperature control structure in the battery pack 10 through a fluid circulation loop. The working fluid is a substance that heats or cools the cell; it can be a liquid, a gas, or a gas-liquid mixture. By supplying the working fluid to the temperature control structure in the battery pack 10, the cell can be heated using a higher-temperature working fluid, allowing the cell temperature to rise continuously until it reaches the minimum operating temperature and enters the normal operating temperature range.

[0041] The fluid circulation loop is a fluid delivery pipeline designed in the energy storage system to control the temperature of the cells in each battery pack 10. In practice, the fluid circulation loop can be connected to a liquid cooling unit 20, which can convert the heat-absorbing working fluid into a cryogenic working fluid. The liquid cooling unit 20 may also include a heater to heat the working fluid. Solenoid valves can be designed into the fluid circulation loop to control the flow of the working fluid, thereby enabling or stopping the delivery of the working fluid to the temperature control structure within the battery pack 10.

[0042] During the heating process of the battery cells, the temperature of the battery cells located at different positions in the battery pack 10, as well as the temperature of the battery cells themselves at different positions, can be monitored in real time. This allows us to know the temperature changes of the battery cells and the current temperature results, providing a basis for controlling or stopping the delivery of the working fluid.

[0043] Step S120: Determine whether the temperature difference between different positions of the battery cell exceeds the preset temperature difference threshold. If the maximum temperature difference between two positions of the battery cell exceeds the preset temperature difference threshold, control the fluid circulation loop to stop supplying working fluid to the temperature control structure until the maximum temperature difference between two positions of the battery cell is lower than the preset temperature difference threshold, and then control the fluid circulation loop to supply working fluid to the temperature control structure again.

[0044] During the heating process of the battery cell, the heat transfer path to different parts of the cell differs due to the different paths of the temperature control structure. This results in varying heating rates at different locations within the cell, leading to significant temperature differences. These temperature differences can cause performance degradation during charging and discharging. By pausing the supply of working fluid to the temperature control structure, heating of the cell can be paused. This allows the temperature difference between the hotter and colder parts of the cell to gradually decrease, bringing the temperatures closer together. Once the maximum temperature difference between the two locations falls below a preset threshold, the fluid circulation loop is controlled to resume supplying working fluid to the temperature control structure, continuing the heating process once the temperatures of the different parts are consistent or nearly equal.

[0045] In practice, the preset temperature difference threshold can be set according to the minimum temperature difference required for normal operation of the battery cell. The preset temperature difference threshold limits the maximum temperature difference between two locations within the battery cell, enabling the battery cell to charge and discharge with a relatively small temperature difference within itself.

[0046] Step S130: When the temperature of each cell is not lower than the preset temperature threshold, the control fluid circulation loop stops supplying working fluid to the temperature control structure.

[0047] When the temperature of each cell in the energy storage system is heated to a level not lower than the preset temperature threshold, the control fluid circulation loop stops supplying working fluid to the temperature control structure. When the temperature of each cell is not lower than the preset temperature threshold, it indicates that the cells in the energy storage system have reached the minimum operating temperature and entered the normal operating temperature range. At this time, the cells can begin charging and discharging, and the energy storage system can normally input or output electrical energy.

[0048] In practice, the temperature at the lowest point of the battery cell can be detected. For example, when the temperature control structure is located at the bottom of the battery cell, the temperature sensor can be placed at the top of the battery cell. By detecting the temperature at the top of the battery cell, the lowest temperature of the battery cell can be determined. When the lowest temperature of the battery cell reaches or exceeds a preset temperature threshold, the heating process of the battery cell is completed, and the battery cell reaches the temperature condition for normal charging and discharging.

[0049] The thermal management method for an energy storage system provided in some embodiments of this application, when the cell temperature is lower than a preset temperature threshold, controls the fluid circulation loop to deliver working fluid to the temperature control structure in the battery pack 10, using the heat of the working fluid to heat the cell. During the heating process, it is determined whether the temperature difference between different locations of the cell exceeds a preset temperature difference threshold. When the maximum temperature difference between two locations of the cell exceeds the preset temperature difference threshold, the fluid circulation loop is stopped delivering working fluid to the temperature control structure of the battery pack 10 until the maximum temperature difference between the two locations of the cell is lower than the preset temperature difference threshold, ultimately ensuring that the temperature of each cell reaches or exceeds the preset temperature threshold. This controls the temperature difference between different locations of the cell during the heating process, preventing large temperature differences at the start of charging and discharging, thus avoiding impacting the cell's performance.

[0050] It should be noted that during the heating process of the battery cell, a significant temperature difference exists between the cell and the working fluid, and the heat transfer from the cold plate to the cell is from bottom to top. Therefore, a large temperature difference occurs between different locations within the cell, which negatively impacts the lifespan of the energy storage system. However, experiments have shown that briefly stopping the heating process can effectively reduce the temperature difference between different locations within the cell. The experimental results are as follows: Figure 2 As shown, Figure 2 The diagram illustrates the temperature change process at different heights of the battery cell, where the horizontal axis represents time in hours (h) and the vertical axis represents temperature in degrees Celsius (°C). Figure 2 In the diagram, the black, red, and blue curves represent the temperature detection results at the top, middle, and bottom of the battery cell, respectively. These results can be obtained by placing temperature sensors at the top, middle, and bottom of the battery cell. The blue curve shows the area where the battery cell temperature drops sharply during the period of paused heating. It can be seen that within approximately 20 minutes, the temperature at different locations on the battery cell has become more uniform.

[0051] In practice, when the ambient temperature is high, causing the battery cells themselves to reach high temperatures, cooling can be applied to the battery cells in the battery pack 10. That is, if the temperature of a battery cell exceeds the maximum temperature required for normal operation before charging or discharging, a coolant, such as a coolant, can be circulated in the fluid circulation loop. Once the coolant reaches the temperature control structure of the battery pack 10, it absorbs and carries away the heat from the battery cells, thus lowering their temperature. During the cooling process, the temperature difference between different locations within the battery cell can be detected to determine if it exceeds a preset temperature difference threshold. If a significant temperature difference is observed, the supply of coolant to the temperature control structure is stopped, ensuring that the temperatures at different locations within the battery cells in the battery pack 10 become uniform or similar, ultimately bringing all battery cells to the required normal operating temperature range.

[0052] In some embodiments, after determining whether the temperature difference between different locations of the battery cell exceeds a preset temperature difference threshold in step S120, the following steps may also be included:

[0053] Step S121: Obtain the average temperature of multiple cells in the battery pack and the average temperature of multiple cells in the energy storage system.

[0054] Based on the temperatures at the same locations of multiple cells in the battery pack 10, the average temperature of the multiple cells in the battery pack 10 and the average temperature of the multiple cells in the energy storage system are obtained. The average temperature of the multiple cells in the battery pack 10 reflects the heating status of the internal cells when fluid flows through the temperature control structure, providing a basis for judging the overall temperature change of different battery packs 10. The average temperature of the multiple cells in the energy storage system reflects the temperature change of the entire energy storage system during heating processes.

[0055] Step S122: Determine whether the average temperature of multiple cells in the battery pack is higher than the average temperature of multiple cells in the energy storage system. If the average temperature of multiple cells in the battery pack is higher than the average temperature of multiple cells in the energy storage system, then control the fluid circulation loop to stop supplying working fluid to the temperature control structure of the battery pack.

[0056] The average temperature of multiple cells in an energy storage system reflects the overall temperature range and temperature changes of the energy storage system during the initial heating process. By determining whether the average temperature of multiple cells in a single battery pack 10 exceeds the average temperature of multiple cells in the entire energy storage system, it can be determined whether the cells in a particular battery pack 10 are heating up too quickly, thus creating a large temperature difference with the cells in other battery packs 10 and affecting the temperature uniformity of different battery packs 10.

[0057] When it is known that the average temperature of multiple cells in a certain battery pack 10 or some battery packs 10 exceeds the average temperature of multiple cells in the energy storage system, the fluid circulation loop can be controlled to stop supplying working fluid to the temperature control structure of the corresponding battery pack 10. By stopping the supply of working fluid, the temperature of the cells in the battery pack 10 that heats up faster can be slowed down and decrease to a certain extent, thereby keeping the temperature of different battery packs 10 relatively consistent or close.

[0058] When the average temperature of multiple cells in the battery pack 10 is not higher than the average temperature of multiple cells in the energy storage system, the control fluid circulation loop continues to deliver working fluid to the temperature control structure of the battery pack to continue the heating process.

[0059] In practice, the judgment condition in step S120 and the condition judgment in step S121 can be used in combination. That is, when the maximum temperature difference between two positions of the cell in the energy storage system exceeds the preset temperature difference threshold, and the average temperature of multiple cells in the battery pack 10 is higher than the average temperature of multiple cells in the energy storage system, the control fluid circulation loop stops delivering working fluid to the temperature control structure of the battery pack 10.

[0060] Figure 3 Taking a preset temperature threshold of 10℃ and a preset temperature difference threshold of 5℃ as an example, the cell temperature control process is illustrated. When the cell temperature is below 10℃, the heating mode of the liquid cooling unit 20 in the energy storage system is turned on to heat the cells in the battery pack 10. When the temperature difference of the cells in the battery pack exceeds 5℃, the fluid circulation loop is controlled to stop supplying working fluid to the temperature control structure of the battery pack 10 until the cell temperature difference is less than 5℃ and reaches within 3℃. Then, the working fluid is supplied to the temperature control structure of the battery pack 10 again. In this way, the temperature difference between different positions of the cell is controlled within a certain range when the cell is heated.

[0061] In some embodiments, a plurality of battery packs 10 can form a battery cluster 100 in a preset number. After determining whether the temperature difference between different locations of the battery cells exceeds a preset temperature difference threshold in step S120, the following steps are also included:

[0062] Step S123: Obtain the average temperature of multiple cells in the battery cluster and the average temperature of multiple cells in the energy storage system.

[0063] Multiple battery packs 10 can form a battery cluster 100 for unified management. Multiple battery clusters 100 can be designed in the energy storage system, such as 9, 10, or 11 battery clusters 100. Different battery clusters 100 have different fluid inlets and outlets in the main pipeline of the fluid circulation loop. These inlets and outlets allow the fluid flowing in the circulation loop to reach the temperature control structures within the multiple battery packs 10 in the battery cluster 100, and after transferring heat to the cells, it flows back. The number of battery packs 10 in the battery cluster 100 can be 5, 6, 7, or 8; this embodiment does not limit this.

[0064] Based on the temperatures at the same locations of multiple cells within the battery pack 10 of the battery cluster 100, the average temperature of the multiple cells in the battery cluster 100 and the average temperature of the multiple cells in the energy storage system are obtained. The average temperature of the multiple cells in the battery cluster 100 reflects the heating status of the internal cells when fluid flows through the temperature control structure of the battery pack 100, providing a basis for judging the overall temperature change of different battery clusters 100. The average temperature of the multiple cells in the energy storage system reflects the temperature change of the entire energy storage system during heating processes.

[0065] Step S124: Determine whether the average temperature of multiple cells in the battery cluster is higher than the average temperature of multiple cells in the energy storage system. If the average temperature of multiple cells in the battery cluster is higher than the average temperature of multiple cells in the energy storage system, then control the fluid circulation loop to stop supplying working fluid to the temperature control structure of the battery pack in the battery cluster.

[0066] Based on the average temperature of multiple cells in the battery cluster 100, after obtaining the average temperature of multiple cells in a single battery cluster 100, the average temperature of multiple cells in a single battery cluster 100 is compared with the average temperature of multiple cells in the energy storage system to determine whether the average temperature of multiple cells in the battery cluster 100 exceeds the average temperature of multiple cells in the energy storage system.

[0067] When the average temperature of multiple cells in a certain battery cluster 100 or some battery clusters 100 exceeds the average temperature of multiple cells in the energy storage system, the fluid circulation loop can be controlled to stop supplying working fluid to the temperature control structure of multiple battery packs 10 in the battery cluster 100, so that the cells in the multiple battery packs 10 in the battery cluster 100 can be temporarily de-heated, so as to achieve cluster-level temperature control of the energy storage system.

[0068] When the average temperature of multiple cells in the battery cluster 100 is not higher than the average temperature of multiple cells in the energy storage system, the fluid circulation loop can be controlled to continue to deliver working fluid to the temperature control structure of multiple battery packs 10 in the battery cluster 100.

[0069] In some embodiments, a plurality of battery packs 10 can form a battery cluster 100 in a predetermined number. During the heating of the battery cells in step S110, the following steps are also included:

[0070] Step S111: Obtain the temperature of different battery packs in the battery cluster. The temperature of the battery pack is the average temperature of multiple cells in the battery pack.

[0071] Step S112: Determine whether the temperature difference between different battery packs in the battery cluster is higher than the preset temperature difference value. If the maximum temperature difference between two battery packs in the battery cluster is higher than the preset temperature difference value, then control the fluid circulation loop to stop supplying working fluid to the temperature control structure of the battery pack in the battery cluster.

[0072] In other words, when controlling the cell temperature at the cluster level in an energy storage system, the temperature difference between different battery packs 10 in the same battery cluster 100 can be detected in order to determine whether there is an excessive temperature difference between different battery packs 10.

[0073] In practice, the temperature control structures within different battery packs 10 of the same battery cluster 100 are connected to the same fluid supply port and the same fluid return port on the main pipeline of the fluid circulation loop. Due to the different locations of each battery pack 10, the fluid transport paths are also different, making it easy for large temperature differences to occur between different battery packs 10 in the battery cluster 100. This results in battery packs 10 at different locations operating under conditions of large temperature differences, meaning that the cells in some battery packs 10 operate at higher temperatures, while the cells in some battery packs 10 operate at lower temperatures, which also affects the lifespan of the cells. Therefore, when performing cluster-level temperature control on the cells in the energy storage system, it is possible to determine whether some battery packs 10 in a particular battery cluster 100 or several battery clusters 100 are experiencing excessively rapid temperature rise.

[0074] If the maximum temperature difference between two battery packs 10 in the battery cluster 100 exceeds a preset temperature difference value, the fluid circulation loop can be controlled to stop supplying working fluid to the temperature control structure of the battery packs 10 within the battery cluster 100, so that the temperatures of the different battery packs 10 in the battery cluster 100 can become consistent or close. If the maximum temperature difference between two battery packs 10 in the battery cluster 100 is lower than the preset temperature difference value, there is no need to stop supplying working fluid, and the heating of the cells in the different battery packs 10 in the battery cluster 100 can continue.

[0075] In practical applications, when it is necessary to control the temperature difference between the two battery packs 10 within the battery cluster 100, the supply of working fluid to the temperature control structure of the battery pack that heats up faster can be stopped. Instead, the flow rate of the working fluid in the main pipeline of the fluid circulation loop can be increased before it is supplied to the temperature control structure of the battery pack that heats up slower. This allows the cell temperature in the faster-heating battery pack to decrease to a certain extent, while effectively increasing the cell temperature in the slower-heating battery pack. Consequently, the temperatures of the two battery packs with a large temperature difference can quickly converge or approach each other, saving heating time for the cells in the battery cluster 100. Flow rate regulation can be achieved by installing a flow regulating valve in the fluid circulation loop, and the flow rate can be measured using a flow meter.

[0076] In some embodiments, after the control fluid circulation loop stops supplying working fluid to the temperature control structure of the battery pack within the battery cluster in step S112, the following steps may also be included:

[0077] Step S113: Determine whether the temperature difference between two battery packs in the battery cluster is lower than the preset temperature difference value. If the temperature difference between two battery packs in the battery cluster is lower than the preset temperature difference value, then determine again whether the temperature difference between different battery packs in the battery cluster is higher than the preset temperature difference value.

[0078] In other words, after the temperatures of the two battery packs 10 with the largest temperature difference in the battery cluster 100 tend to be consistent or close, it can be determined again whether the temperature difference between other battery packs 10 in the battery cluster 100 exceeds the preset temperature difference value, thereby ensuring that nothing is missed and repeating the confirmation after the cell temperature changes. If the temperature difference between the two battery packs 10 in the battery cluster 100 is not lower than the preset temperature difference value, the supply of working fluid to the temperature control structure of the battery packs 10 in the battery cluster 100 is stopped, and the temperature homogenization process of the battery packs 10 in the battery cluster 100 continues.

[0079] For example, in step S112, if the temperature difference between PACK4-1 and PACK4-2 is the maximum temperature difference between two battery packs 10 in the battery cluster 100 and exceeds a preset temperature difference value, then by stopping the supply of working fluid to the temperature control structure of the multiple battery packs 10 in the battery cluster 100, the temperatures of PACK4-1 and PACK4-2 can be made consistent or close. In step S113, if the temperature difference between PACK4-1 and PACK4-2 is lower than the preset temperature difference value, then it is determined again whether the temperature difference between the other two battery packs 10 exceeds the preset temperature difference value.

[0080] In some embodiments, the energy storage system may further include a water pump 104 located on a fluid circulation loop, the water pump 104 being correspondingly disposed with respect to the battery cluster 100. After controlling the fluid circulation loop to stop supplying working fluid to the temperature control structure of the battery pack within the battery cluster in step S112, the system further includes the following steps:

[0081] Step S114: Connect the temperature control structures in the two battery packs with the largest temperature difference to both ends of the water pump.

[0082] The water pump 104 is connected to the temperature control structure in the two battery packs 10 with the largest temperature difference. The water pump 104 can control the flow of fluid in the different temperature control structures in the loop formed by the water pump 104, so that the temperature of the two battery packs 10 with the largest temperature difference can be made consistent or close under the control of the water pump 104.

[0083] Step S115: Turn on the water pump to circulate the working fluid in the temperature control structure of the two battery packs with the largest temperature difference.

[0084] After the water pump 104 is turned on, the circuit formed by the water pump 104 allows the working fluid to circulate through the temperature control structures in the two battery packs 10 with the largest temperature difference. In other words, the temperature control structures in the two battery packs 10 with the largest temperature difference are connected to both ends of the water pump 104, and the water pump 104 can actively control the circulation of the working fluid in the circuit formed by the water pump 104. By utilizing the control action of the water pump 104, the temperature of the two battery packs 10 with a large temperature difference can be controlled, thereby allowing the temperatures of the two battery packs 10 to converge to the same level in a shorter time, reducing the time required for temperature adjustment.

[0085] In addition, after starting the water pump in step S115, the following steps may also be included:

[0086] Step S116: Determine whether the working time of the water pump exceeds the preset time. If the working time of the water pump 104 exceeds the preset time, turn off the water pump and control the fluid circulation loop to re-supply the working fluid to the temperature control structure of the battery pack in the battery cluster.

[0087] The preset time can be set to within one hour, such as 30 to 50 minutes. When the temperature difference is large, it can also be set to more than one hour. Setting the preset time can prevent the water pump 104 from working for too long, thereby avoiding affecting the subsequent temperature regulation and the normal operation of the energy storage system.

[0088] In some embodiments, the fluid input terminals of the temperature control structures of the multiple battery packs 10 in the battery cluster 100 can be interconnected, and the fluid output terminals of the temperature control structures of the multiple battery packs 10 in the battery cluster 100 can be interconnected.

[0089] In other words, the temperature control structures of multiple battery packs 10 in the battery cluster 100 are connected in parallel to the main pipeline of the fluid circulation loop. They can simultaneously receive the working fluid supplied by one of the main pipelines of the fluid circulation loop, and when the working fluid flows out of the temperature control structure, it merges and flows back to the other main pipeline of the fluid circulation loop.

[0090] like Figure 4 and Figure 5 As shown, the energy storage system includes a first solenoid valve 101 and a second solenoid valve 102 corresponding to the battery cluster 100, and a third solenoid valve 103 corresponding to the battery pack 10. The first solenoid valve 101 is located at the fluid input end of the temperature control structure of the multiple battery packs 10 in the battery cluster 100, the second solenoid valve 102 is located at the fluid output end of the temperature control structure of the multiple battery packs 10 in the battery cluster 100, and the third solenoid valve 103 is located between the first solenoid valve 101 and the fluid input end of the temperature control structure.

[0091] Both the first solenoid valve 101 and the second solenoid valve 102 are correspondingly configured for each battery cluster 100, meaning that each battery cluster 100 has one first solenoid valve 101 and one second solenoid valve 102 installed in its fluid circuit. The first solenoid valve 101 and the second solenoid valve 102 are located at the fluid inlet and fluid outlet of the temperature control structure of the multiple battery packs 10 within the battery cluster 100, respectively. The first solenoid valve 101 and the second solenoid valve 102 can control the inflow and outflow of the working fluid into the temperature control structure of the multiple battery packs 10 within the battery cluster 100. When the first solenoid valve 101 and the second solenoid valve 102 are closed, the supply of working fluid to the temperature control structure of all battery packs 10 within the battery cluster 100 will cease.

[0092] The third solenoid valve 103 is correspondingly provided to each battery pack 10, meaning that a third solenoid valve 103 is provided on the fluid circuit of the temperature control structure of each battery pack 10 in the battery cluster 100. The third solenoid valve 103 is located at the fluid input end of the temperature control structure of the battery pack 10 and at the fluid output end of the first solenoid valve 101. When the third solenoid valve 103 is closed, the supply of working fluid to the corresponding temperature control structure of the battery pack 10 will stop.

[0093] By setting different solenoid valves at different locations, it is beneficial to control the delivery path of the working fluid, thereby controlling the flow path of the working fluid when performing thermal management on the cells in the energy storage system. When it is necessary to control the fluid circulation loop to stop delivering the working fluid to the temperature control structure of the battery pack 10, the third solenoid valve 103 can be closed. When it is necessary to control the fluid circulation loop to stop delivering the working fluid to the temperature control structure of all battery packs 10 in the battery cluster 100, the first solenoid valve 101 and the second solenoid valve 102 can be closed simultaneously.

[0094] Additionally, the step S114, which connects the temperature control structures in the two battery packs with the largest temperature difference to both ends of the water pump, may include the following steps:

[0095] Step S1141: Connect the water pump to the temperature control structure of any two battery packs in the battery cluster.

[0096] like Figure 4 and Figure 5 As shown, in a single battery cluster 100, the fluid input terminals of the temperature control structures of all battery packs 10 are connected to the fluid output terminal of the first solenoid valve 101, and the fluid output terminals of the temperature control structures of all battery packs 10 are connected to the fluid input terminal of the second solenoid valve 102. The water pump 104 can be connected in parallel to the output circuits of the temperature control structures of multiple battery packs 10, or it can be connected in parallel to the input circuits of the temperature control structures of multiple battery packs 10. Figure 4 and Figure 5 The following example illustrates the application of a water pump 104 connected in parallel to the output circuit of a temperature control structure for multiple battery packs 10.

[0097] Step S1142: Close the first solenoid valve and the second solenoid valve.

[0098] When it is necessary to keep the temperature of the two battery packs 10 in the battery cluster 100 consistent or close, the first solenoid valve 101 and the second solenoid valve 102 can be controlled to enter the closed state, so that the fluid circulation loop stops supplying working fluid to the temperature control structure of the multiple battery packs 10 in the battery cluster 100, so that the water pump 104 can actively control the temperature of the two battery packs 10 without being affected by the outside world, so that the temperature of the two battery packs 10 can reach a consistent or close state in a short time.

[0099] Step S1143: Close the third solenoid valve connected to the temperature control structure in all battery packs except the two battery packs with the largest temperature difference.

[0100] When controlling the temperature of the two battery packs 10 with the largest temperature difference, the third solenoid valve 103 connected to the temperature control structure of the other battery packs 10 besides the two battery packs 10 with the largest temperature difference can be closed. For example, when controlling the temperature balance of the first and second battery packs in the fourth battery cluster, namely PACK4-1 and PACK4-2, the third solenoid valve 103 connected to the temperature control structure of PACK4-3, PACK4-4, PACK4-5, PACK4-6, ..., PACK4-n can be closed. After closing part of the third solenoid valve 103, the temperature control structure of the two battery packs 10 with the largest temperature difference can be in the circulation loop of the water pump 104. Turning on the water pump 104 can control the temperature of the two battery packs 10 with the largest temperature difference, so that the temperatures of the two battery packs 10 with the largest temperature difference gradually reach a consistent or similar state.

[0101] In practice, the water pump 104 can also be connected in parallel to the main fluid circuit. When performing cluster-level temperature control, the input of the working fluid to the temperature control structure of the battery pack 10 in the two battery clusters 100 can be suspended. By turning on the water pump 104, the working fluid can circulate in the temperature control structure of the battery pack 10 in the two battery clusters 100, thereby achieving temperature equalization adjustment of different battery clusters 100 and realizing cluster-level temperature control.

[0102] Figure 5Taking a preset time of 1 hour as an example, the cluster-level temperature control of the energy storage system is illustrated. When the liquid cooling unit is not in cooling mode, the temperature difference between different battery packs within the battery cluster is checked to see if it exceeds the preset temperature difference value. If the temperature difference between two battery packs exceeds the preset value, the cluster-level solenoid valves (i.e., the first and second solenoid valves) are closed, and the third solenoid valve connected to the temperature control structure of all battery packs except the highest and lowest temperature battery packs is also closed. Then, the water pump is turned on to equalize the temperature of the two battery packs with the largest temperature difference. If the water pump runs for more than 1 hour, it is turned off, and the cells in the battery pack are reheated. When the temperature difference between the two battery packs is less than the preset temperature difference value, the temperature difference between different battery packs within the battery cluster is compared and judged again, and the cluster-level temperature control process is repeated.

[0103] In some embodiments, among the multiple cells in the battery pack 10, at least some cells may have multiple temperature sensors arranged sequentially in the height direction.

[0104] In other words, at least some of the battery cells have multiple temperature sensors sequentially arranged along their height. These sensors can detect the temperature at corresponding locations within the cell, thus revealing the temperature conditions at different points along the cell's height. When the temperature control structure is located at the bottom of multiple battery cells, the heat transfer from the structure to different locations within the cell varies, resulting in significant temperature differences between different locations along the cell's height. By sequentially arranging multiple temperature sensors along the height of the battery cell, the temperature changes and distribution along this direction can be better monitored.

[0105] In practice, multiple temperature sensors can be arranged on one of the multiple cells within a certain range within the battery pack 10. For example, multiple temperature sensors can be arranged along the height of one of every five or six cells, while other cells only have temperature sensors at their top, thus saving on the number of temperature sensors required. The arrangement direction of the temperature sensors can be determined based on the arrangement direction of the cells and the temperature control structure. When the temperature control structure or the cells are placed on their sides, the temperature sensors can also be arranged along the length or width of the cells.

[0106] In some embodiments, the preset temperature difference threshold may be greater than or equal to 3°C.

[0107] The preset temperature difference threshold is the maximum temperature difference required between different locations within the battery cell. By controlling the range of the preset temperature difference threshold, excessive temperature differences between different locations within the battery cell after heating can be avoided due to a large preset temperature difference threshold, thus preventing impact on the battery cell's performance and lifespan. In practice, the preset temperature difference threshold can also be controlled within a range of less than or equal to 10℃ to avoid excessively long heating times for the energy storage system due to a threshold that is too small, which could affect the system's timely entry into normal charging and discharging states. In other words, the preset temperature difference threshold can be set within the range of 3℃ to 10℃, for example, at 3℃, 4℃, 5℃, 6℃, 7℃, 8℃, 9℃, or 10℃.

[0108] In addition, the preset temperature threshold, i.e., the minimum operating temperature required by the battery cell, can be set from 10℃ to 30℃. For example, the preset temperature threshold can be 10℃, 15℃, 20℃, 25℃, or 30℃. When the minimum temperature of the battery cell is not lower than the preset temperature threshold, the battery cell can be charged and discharged under optimal temperature conditions, which can fully utilize the performance of the battery cell and prevent lithium plating due to low temperature. Furthermore, the preset temperature threshold has a certain gap from the maximum operating temperature required by the battery cell, which can prevent the battery cell from experiencing efficiency reduction due to high temperature.

[0109] The preset temperature difference value, which serves as the basis for comparing the temperature difference between the two battery packs 10, can be set from 5℃ to 15℃. When the temperature difference between the two battery packs 10 is lower than the preset temperature difference value, the fluid circulation loop can be controlled to continue supplying working fluid to the temperature control structure of the battery pack 10. This controls the temperature difference between the different battery packs 10 during the heating process, ensuring temperature consistency between the cells of the different battery packs 10. In practice, the preset temperature difference value can be 5℃, 7℃, 9℃, 11℃, 13℃, or 15℃.

[0110] The average temperature of multiple cells in the energy storage system is the average of the temperatures measured by the temperature sensors at the top of all cells in the energy storage system. Similarly, the average temperature of multiple cells in PACKm-n is the average of the temperatures measured by the temperature sensors at the top of all cells in PACKm-n. Here, m represents the position of battery cluster 100 in the energy storage system, and n represents the position of battery pack 10 within battery cluster 100. For example, when m is 1, it represents the first battery cluster in the energy storage system; when n is 1, it represents the first battery pack within battery cluster 100.

[0111] In practice, when the lowest temperature of a single cell exceeds 10°C, it indicates that the cell temperature has reached the temperature at which it can charge and discharge normally. Therefore, the solenoid valve can be closed to reduce the system load.

[0112] During the heating process of low-temperature battery cells, if the temperature difference between different locations of the battery cells is greater than 5℃, and the average temperature of multiple battery cells in PACKm-n is higher than the average temperature of multiple battery cells in the energy storage system, it indicates that the temperature difference between the battery cells is large, and the solenoid valve needs to be closed for temperature equalization. However, if the heating process is stopped when the average temperature of multiple battery cells in PACKm-n is lower than the average temperature of multiple battery cells in the energy storage system, the heating time of the energy storage system will be too long, and it will be unable to charge and discharge quickly. Therefore, a condition can be set to ensure that the average temperature of multiple battery cells in PACKm-n is higher than the average temperature of multiple battery cells in the energy storage system. Only when the condition is met will the solenoid valve be closed for temperature equalization.

[0113] Once the temperature of all cells in the battery pack 10 within the energy storage system reaches the operating temperature, for example, above 10°C, the energy storage system will shut down the heating mode of the liquid cooling unit 20 and allow the entire system to stand still until the temperature difference between different locations of all individual cells being tested is less than 3°C before starting charging and discharging, in order to ensure that the cells are charged and discharged when their own temperature difference is small.

[0114] Some embodiments of this application also provide an energy storage system, which includes multiple battery packs 10 and a fluid circulation loop. The battery packs 10 have multiple battery cells and a temperature control structure for regulating the temperature of the multiple battery cells. The fluid circulation loop is used to deliver working fluid to the temperature control structure to heat or cool the battery cells.

[0115] Energy storage systems also include battery management systems, which are used for:

[0116] The temperature of each cell in the battery pack 10 is detected. If the temperature of a cell is lower than a preset temperature threshold, the fluid circulation loop is controlled to deliver working fluid to the temperature control structure to heat the cell.

[0117] Determine whether the temperature difference at different locations of the battery cell exceeds the preset temperature difference threshold. If the maximum temperature difference between two locations of the battery cell exceeds the preset temperature difference threshold, control the fluid circulation loop to stop supplying working fluid to the temperature control structure until the maximum temperature difference between the two locations of the battery cell is lower than the preset temperature difference threshold, and then control the fluid circulation loop to supply working fluid to the temperature control structure again.

[0118] When the temperature of each cell is not lower than the preset temperature threshold, the control fluid circulation loop stops supplying working fluid to the temperature control structure.

[0119] The energy storage system includes a control unit, a liquid cooling unit 20, a fluid circulation loop, and a battery pack 10. The control unit, also known as the battery management system, can monitor the cell temperature, cell charging and discharging status, the operating status of the liquid cooling unit 20, and the status of the solenoid valves in real time, and control the cell charging and discharging, the switching of the operating mode of the liquid cooling unit 20, and the switching of the solenoid valves. The fluid circulation loop includes a temperature control structure connecting the battery pack 10 and the liquid cooling pipeline of the liquid cooling unit 20. Solenoid valves are installed on the liquid cooling pipeline. A cold plate is installed below the cells in the battery pack 10 as a temperature control structure. The battery pack 10 includes a housing, cells, temperature sensors arranged on top of the cells, and other auxiliary electrical and structural components. Most temperature sensors are arranged on the top of the cells. One or more cells will have multiple temperature sensors evenly arranged in the height direction to detect the temperature distribution at different locations of the cells and transmit the signals to the battery management system. A battery pack 10 can have multiple temperature sensors arranged on different cells.

[0120] If the cell temperature is too low, charging and discharging at this time will cause lithium plating, thereby reducing the cell life and system safety. Therefore, in this case, it is necessary to use a liquid cooling unit 20 with a high output temperature cooling medium to heat up the cell until the cell temperature reaches the normal operating temperature before charging and discharging can begin.

[0121] Depending on the application scenario, energy storage systems can adopt cabin-level, cluster-level, and pack-level energy storage forms. Battery cells, i.e., individual battery cells, can be connected in series or parallel to form modules, which are then arranged in a container to form a battery pack 10. An energy storage system can contain one or more battery packs 10, and a certain number of battery packs 10 can be uniformly managed and controlled to form a battery cluster 100. Multiple battery clusters 100 can be packaged in a large container to form a containerized energy storage system. Multiple battery clusters 100 can be jointly managed and controlled through a battery management system and a thermal management system.

[0122] Some embodiments of this application also provide an electrical device, which includes the energy storage system described above.

[0123] Electrical equipment can be everyday consumer goods, industrial products, or other devices equipped with electrochemical energy storage systems as their energy source.

[0124] Those skilled in the art will understand that the above embodiments are specific implementations of this application, and in practical applications, various changes can be made in form and detail without departing from the spirit and scope of this application.

Claims

1. A thermal management method for an energy storage system, the energy storage system comprising a plurality of battery packs and a fluid circulation loop, the battery packs having a plurality of cells and a temperature control structure for temperature regulating the plurality of cells, the fluid circulation loop for delivering a working fluid to the temperature control structure for heating or cooling the cells, characterized in that, The thermal management method of the energy storage system comprises: detecting the temperature of each battery cell in the battery pack, and if the temperature of the battery cell is lower than a preset temperature threshold, controlling the fluid circulation loop to deliver working medium to the temperature control structure to heat the battery cell; determining whether the temperature difference between different positions of the battery cell exceeds a preset temperature difference threshold, and if the maximum temperature difference between two positions of the battery cell exceeds the preset temperature difference threshold, controlling the fluid circulation loop to stop delivering working medium to the temperature control structure to suspend heating of the battery cell, so that the temperature difference between the position with higher temperature and the position with lower temperature of the battery cell can gradually decrease until the maximum temperature difference between the two positions of the battery cell is lower than the preset temperature difference threshold, and then controlling the fluid circulation loop to deliver working medium to the temperature control structure again; when the temperature of each battery cell is not lower than the preset temperature threshold, controlling the fluid circulation loop to stop delivering working medium to the temperature control structure.

2. The thermal management method of an energy storage system of claim 1, wherein, After determining whether the temperature difference between different positions of the battery cell exceeds the preset temperature difference threshold, the method further comprises: obtaining the average temperature of multiple battery cells in the battery pack and the average temperature of multiple battery cells in the energy storage system; determining whether the average temperature of multiple battery cells in the battery pack is higher than the average temperature of multiple battery cells in the energy storage system, and if the average temperature of multiple battery cells in the battery pack is higher than the average temperature of multiple battery cells in the energy storage system, controlling the fluid circulation loop to stop delivering working medium to the temperature control structure of the battery pack.

3. The thermal management method of an energy storage system of claim 1, wherein, Multiple battery packs form a battery cluster in a preset number, and after determining whether the temperature difference between different positions of the battery cell exceeds the preset temperature difference threshold, the method further comprises: obtaining the average temperature of multiple battery cells in the battery cluster and the average temperature of multiple battery cells in the energy storage system; determining whether the average temperature of multiple battery cells in the battery cluster is higher than the average temperature of multiple battery cells in the energy storage system, and if the average temperature of multiple battery cells in the battery cluster is higher than the average temperature of multiple battery cells in the energy storage system, controlling the fluid circulation loop to stop delivering working medium to the temperature control structure of the battery pack in the battery cluster.

4. The thermal management method of an energy storage system of claim 1, wherein, Multiple battery packs form a battery cluster, and during the process of heating the battery cell, the method further comprises: obtaining the temperature of different battery packs in the battery cluster, which is the average temperature of multiple battery cells in the battery pack; determining whether the temperature difference between different battery packs in the battery cluster is higher than a preset temperature difference value, and if the maximum temperature difference between two battery packs in the battery cluster is higher than the preset temperature difference value, controlling the fluid circulation loop to stop delivering working medium to the temperature control structure of the battery pack in the battery cluster.

5. The thermal management method of an energy storage system of claim 4, wherein, After controlling the fluid circulation loop to stop delivering working medium to the temperature control structure of the battery pack in the battery cluster, the method further comprises: determining whether the temperature difference between two battery packs in the battery cluster is lower than a preset temperature difference value, and if the temperature difference between two battery packs in the battery cluster is lower than the preset temperature difference value, determining again whether the temperature difference between different battery packs in the battery cluster is higher than the preset temperature difference value.

6. The thermal management method of an energy storage system of claim 4, wherein, The energy storage system further comprises a water pump arranged on the fluid circulation loop and corresponding to the battery cluster, and further comprises, after the fluid circulation loop is controlled to stop delivering the working medium to the temperature control structure of the battery pack in the battery cluster: connecting the temperature control structures in two battery packs with the largest temperature difference to both ends of the water pump; starting the water pump to circulate the working medium in the temperature control structures in the two battery packs with the largest temperature difference.

7. The thermal management method of an energy storage system of claim 6, wherein, After starting the water pump, the method further comprises: determining whether the working time of the water pump exceeds a preset time, and if the working time of the water pump exceeds the preset time, stopping the water pump and controlling the fluid circulation loop to deliver the working medium to the temperature control structure of the battery pack in the battery cluster again.

8. The thermal management method of an energy storage system of claim 6, wherein, The fluid input ends of the temperature control structures of the plurality of battery packs in the battery cluster are connected to each other, and the fluid output ends of the temperature control structures of the plurality of battery packs in the battery cluster are connected to each other. The energy storage system comprises a first electromagnetic valve and a second electromagnetic valve arranged corresponding to the battery cluster, and a third electromagnetic valve arranged corresponding to the battery pack, the first electromagnetic valve is arranged at the fluid input end of the temperature control structure of the plurality of battery packs in the battery cluster, the second electromagnetic valve is arranged at the fluid output end of the temperature control structure of the plurality of battery packs in the battery cluster, and the third electromagnetic valve is arranged between the first electromagnetic valve and the fluid input end of the temperature control structure.

9. The thermal management method of an energy storage system of claim 8, wherein, Connecting the temperature control structures in two battery packs with the largest temperature difference to both ends of the water pump comprises: connecting the water pump to the temperature control structures of any two battery packs in the battery cluster; closing the first electromagnetic valve and the second electromagnetic valve; closing the third electromagnetic valve connected to the temperature control structure of the battery pack other than the two battery packs with the largest temperature difference among the plurality of battery packs.

10. The thermal management method of an energy storage system of claim 1, wherein, Among the plurality of battery cells in the battery pack, at least part of the battery cells are sequentially provided with a plurality of temperature sensors in the height direction.

11. The thermal management method of an energy storage system of claim 1, wherein, The preset temperature difference threshold is greater than or equal to 3℃.

12. An energy storage system characterized by, The energy storage system comprises a plurality of battery packs and a fluid circulation loop, the battery pack comprises a plurality of battery cells and a temperature control structure for temperature regulation of the plurality of battery cells, and the fluid circulation loop is used for delivering a working medium to the temperature control structure to heat or cool the battery cells. The energy storage system further comprises a battery management system, and the battery management system is used for: detecting the temperature of each battery cell in the battery pack, and if the temperature of the battery cell is lower than a preset temperature threshold, controlling the fluid circulation loop to deliver the working medium to the temperature control structure to heat the battery cell; determining whether the temperature difference between different positions of the battery cell exceeds a preset temperature difference threshold, and if the maximum temperature difference between two positions of the battery cell exceeds the preset temperature difference threshold, controlling the fluid circulation loop to stop delivering the working medium to the temperature control structure to suspend heating of the battery cell, so that the temperature difference between the part of the battery cell with higher temperature and the part of the battery cell with lower temperature can gradually decrease until the maximum temperature difference between the two positions of the battery cell is lower than the preset temperature difference threshold, and then controlling the fluid circulation loop to deliver the working medium to the temperature control structure again; controlling the fluid circulation loop to stop delivering the working medium to the temperature control structure when the temperature of each battery cell is not lower than a preset temperature threshold.

13. An electrical device, characterized by The energy storage system of claim 12. The energy storage system of claim 12.

Images