An energy storage battery pack immersion thermal management system and control method

Abstract

This invention discloses an immersion thermal management system and control method for an energy storage battery pack, comprising a sealed battery pack top cover and a lower housing. The lower housing contains a battery unit (BMU), an inlet chamber, a lower housing flow channel, and a battery module cavity. The battery module cavity houses a battery module composed of alternating layers of battery cells, flow guide assemblies, and pressure regulating plates, with end plates at both ends and secured by locking strips. The flow guide assemblies and pressure regulating plates combine to form flow channels. The pressure regulating plates are made of elastic material and can be adjusted for thermal conductivity. The cell expands and compresses, reducing the cross-sectional area of ​​the flow channel, increasing the flow rate, and enhancing heat dissipation. The upper cover is equipped with temperature and pressure sensors. Immersion liquid flows in from the inlet port, through the inlet chamber, the lower shell guide channel, the battery module cavity, the flow channel, the flow hole, the guide channel, and the outlet chamber, and flows out from the top outlet port, achieving six-sided three-dimensional heat exchange of the cell. The BMU controls the circulation pump and heat exchanger based on multiple temperature thresholds to achieve low-temperature heating, medium-temperature circulation, and high-temperature cooling. Simultaneously, it monitors the pressure, initiating pressure relief and fire suppression linkage when limits are exceeded. This invention achieves efficient heat dissipation, pressure self-adaptation, intelligent temperature control, and integrated fire suppression, significantly improving the safety and cycle life of the energy storage system.

Description

Technical Field

[0001] This invention belongs to the field of thermal management technology for energy storage batteries, specifically relating to an immersion thermal management system and control method for energy storage battery packs, which is particularly suitable for the integrated design of immersion cooling, pressure regulation and fire protection for large-capacity energy storage systems. Background Technology

[0002] As energy storage systems develop towards larger capacity and higher energy density, the rate of heat generation and the amount of heat produced by batteries have increased significantly. Traditional air-cooled systems suffer from low heat transfer efficiency and poor temperature uniformity; liquid-cooled systems have problems such as leakage, condensation, and uneven heat conduction along the cell height. While immersion cooling can achieve efficient heat exchange, existing designs have the following shortcomings: First, it does not consider the expansion pressure during the cell's lifespan, affecting the cell's cycle life; second, the insulation effect between the "U"-shaped flow channel plate and the cell is generally poor, and the insulation is easily damaged at high temperatures; third, the fire suppression system and the temperature control system are independent, requiring high-speed communication and resulting in response delays. Therefore, there is an urgent need for an integrated, efficient, and reliable immersion thermal management system and control method. Summary of the Invention

[0003] The purpose of this invention is to provide an immersion thermal management system and control method for energy storage battery packs. By optimizing the module structure, flow channel design and control strategy, it achieves uniform heat dissipation on all six sides of the battery cells, adaptive pressure regulation, intelligent temperature control and integrated fire protection, thereby improving system safety and cycle efficiency.

[0004] To achieve the above objectives, the present invention provides the following technical solution: An immersion thermal management system for an energy storage battery pack includes a battery pack housing, which is formed by a sealed connection between a battery pack top cover and a battery pack bottom housing. The housing has an inlet port and an outlet port. The bottom housing contains a lower housing guide channel and at least one battery module cavity, within which a battery module is housed. Each battery module is composed of multiple cells, guide components, and pressure regulating plates arranged alternately, with end plates at both ends and secured by locking strips. The guide components and pressure regulating plates combine to form multiple flow channels for guiding the immersion liquid around the cells. The front end of the bottom housing has an inlet cavity connected to the inlet port and connected to the battery module via the lower housing guide channel. The battery module cavity is interconnected; the inner side of the upper cover is provided with a flow guide groove and a liquid outlet cavity. The flow guide groove is connected to the flow hole of the FPC fixing plastic part, and the liquid outlet cavity is connected to the liquid outlet port, forming a complete immersion liquid circulation channel; the battery module is also provided with a pressure regulating plate. The pressure regulating plate is configured in conjunction with the flow guide assembly and can be compressed when the battery cell expands, thereby reducing the cross-sectional area of ​​the flow channel, increasing the local flow velocity, and enhancing the heat dissipation capacity; the upper cover is provided with a temperature sensor and a pressure sensor for monitoring the temperature and pressure inside the box; the front end of the lower box is provided with a BMU, which is electrically connected to the temperature sensor and the pressure sensor for collecting sensor data and controlling the operation of the circulation pump and heat exchanger.

[0005] Furthermore, the pressure regulating plate is made of an elastic material, and the flow guiding assembly is made of a rigid material (such as an extruded aluminum part), possessing insulation properties and structural strength.

[0006] Furthermore, the flow guiding assembly is installed in conjunction with the FPC fixing plastic part, and the FPC fixing plastic part is provided with flow holes corresponding to the flow guiding assembly to guide the immersion liquid to be evenly distributed.

[0007] Furthermore, the battery module also includes a flexible FPC, a busbar, and signal acquisition terminals for electrical connection and signal acquisition of the battery cells.

[0008] Furthermore, the front end of the lower housing is provided with a BMU fixing bracket, on which the BMU is installed; the front panel of the lower housing is provided with a power port and a communication terminal for external energy transmission and communication.

[0009] Furthermore, a rubber ring is provided between the upper cover and the lower housing to achieve a seal.

[0010] Furthermore, fire inhibitors are added to the immersion liquid.

[0011] The present invention also provides a method for immersion thermal management control of an energy storage battery pack based on the above system, comprising the following steps: The BMU acquires the immersion liquid temperature monitored by the temperature sensor in real time, which is equivalent to the cell temperature. The BMU compares the collected temperature value with a preset temperature threshold to determine the temperature range. Based on the temperature range, the BMU controls the start-up, shutdown, and operating mode of the circulating pump and heat exchanger to achieve temperature regulation of the battery pack. Meanwhile, the BMU collects the pressure value of the air pressure sensor in real time. When the pressure exceeds the safety threshold, the pressure relief device is activated and an alarm signal is issued.

[0012] Furthermore, the temperature threshold includes a first lower threshold, a first upper threshold, and a second upper threshold, wherein the first lower threshold is the lower limit of the suitable operating temperature of the battery cell, the first upper threshold is the upper limit of the suitable operating temperature of the battery cell, and the second upper threshold is a start-up cooling threshold that is higher than the first upper threshold. The step of controlling according to the temperature range includes: When the temperature is below the first lower threshold, the BMU controls the circulation pump to start and controls the heat exchanger to heat the immersion liquid until the temperature rises to a suitable range. When the temperature is between the first upper limit threshold and the second upper limit threshold, the BMU controls the circulation pump to start, the heat exchanger does not work, and only the heat in the high temperature area is dispersed through circulation. When the temperature exceeds the second upper limit threshold, the BMU controls the circulation pump to start and controls the heat exchanger to cool down until the temperature returns to a suitable range.

[0013] Furthermore, when the BMU detects an abnormal increase in pressure from the barometer or a sharp rise in temperature exceeding the thermal runaway threshold, it determines that there is a risk of thermal runaway and immediately activates the fire alarm linkage. The system then rapidly circulates the immersion liquid containing fire inhibitor to the surface of all battery cells to suppress the spread of fire. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the battery pack of the present invention; Figure 2 This is a schematic diagram of the internal layout of the battery pack; Figure 3 This is a schematic diagram of the lower casing of the battery pack; Figure 4 This is a schematic diagram of the battery pack cover; Figure 5 This is a schematic diagram of the battery module structure; Figure 6 This is a flowchart of the control method of the present invention.

[0015] In the attached diagram: 10-Battery module; 11-Battery; 12-Flow guide assembly; 13-Pressure regulating plate; 14-End plate; 15-Flexible FPC; 16-Busbar; 17-Locking strip; 18-FPC fixing plastic part; 19-Signal acquisition terminal; 20-Battery pack lower housing; 21-Inlet port; 22-Communication terminal; 23-Power port; 24-Rubber ring; 25-Battery module cavity; 26-Lower housing flow guide groove; 27-Inlet cavity; 28-BMU fixing bracket; 29-BMU; 30-Battery pack top cover; 31-Outlet port; 32-Flow guide groove; 33-Outlet cavity; 34-Pressure sensor; 35-Temperature sensor; 100-Flow channel; 200-Flow orifice. Detailed Implementation

[0016] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0017] Example 1: System Structure like Figure 1-4 As shown, the immersion thermal management system for the energy storage battery pack in this embodiment includes a battery pack top cover 30 and a battery pack lower housing 20, which are sealed together by a rubber ring 24. The front panel of the lower housing 20 is provided with a power port 23 and a communication terminal 22 for external energy transmission and communication. The lower housing 20 is also provided with a liquid inlet port 21, and the top cover 30 is provided with a liquid outlet port 31, which are respectively connected to an external circulation system.

[0018] The lower housing 20 contains a lower housing guide channel 26 and four battery module cavities 25, each housing a battery module 10. Each battery module 10 is composed of multiple battery cells 11, a guide assembly 12, and a pressure regulating plate 13 arranged in alternating layers (see...). Figure 5 Specifically, a flow guiding assembly 12 and a pressure regulating plate 13 are installed between every two battery cells. End plates 14 are provided at both ends of the battery module and are fixed by locking strips 17. The flow guiding assembly 12 and the pressure regulating plate 13 combine to form multiple flow channels 100, which can guide the immersion liquid in the battery module cavity 25 to the top of the module, while simultaneously wetting the large surface of the battery 11. The FPC fixing plastic part 18 has flow holes 200 that cooperate with the flow channels 100 to further guide the immersion liquid to flow evenly around the battery cell 11.

[0019] The pressure regulating plate 13 is made of an elastic material (such as silicone rubber). When the battery cell 11 expands during cyclic use, it compresses and deforms the adjacent pressure regulating plate 13, thereby reducing the cross-sectional area of ​​the flow channel. According to fluid mechanics principles, the increased flow velocity leads to a higher local heat transfer coefficient, thus enhancing heat dissipation and compensating for the increased internal thermal resistance after the battery cell expands. Simultaneously, the elastic deformation of the pressure regulating plate 13 releases the mechanical stress generated by the battery cell expansion, protecting the battery cell from damage caused by excessive pressure.

[0020] The battery module 10 also includes a flexible FPC 15, a busbar 16, and a signal acquisition terminal 19 for electrical connection and signal acquisition of the battery cells. A BMU mounting bracket 28 is installed at the front end of the lower housing 20, on which a BMU 29 is fixed for acquiring and processing signals from the sensors and the FPC.

[0021] The immersion fluid circulation path is as follows: The immersion fluid enters from the inlet port 21, flows into the inlet chamber 27, and then is evenly distributed to the bottom of each battery module cavity 25 via the lower housing guide channel 26. As the liquid level rises, the immersion fluid flows around the cell 11 through the flow channel 100 and flow holes 200, achieving six-sided heat dissipation. When the liquid level reaches the top, the immersion fluid enters the guide channel 32 inside the upper cover 30, collects in the outlet chamber 33, and finally flows out from the outlet port 31, returning to the external circulation system.

[0022] The top cover 30 is also equipped with a pressure sensor 34 and a temperature sensor 35, which are used to monitor the pressure and temperature inside the chamber in real time and transmit the signals to BMU29.

[0023] The immersion fluid is an insulating coolant, such as fluorinated liquid or mineral oil, and fire inhibitors can be added to achieve fire protection function.

[0024] Example 2: Control Method like Figure 6 As shown, the control method of the present invention includes the following steps: S1: BMU29 acquires data from temperature sensor 35 and pressure sensor 34 in real time. The temperature sensor is immersed in the immersion liquid, and its measured value can be equivalent to the cell temperature; the pressure sensor monitors the pressure inside the chamber.

[0025] S2: BMU29 compares the temperature value with preset thresholds. The preset thresholds are set according to the characteristics of the battery cell, for example: the first lower threshold T_low=15℃, the first upper threshold T_mid=35℃, and the second upper threshold T_high=38℃ (the specific values ​​can be adjusted according to the actual battery cell).

[0026] S3: Implement different strategies based on the temperature range: If T < T_low, the battery cell is in the low temperature range. Start the circulation pump and turn on the heat exchanger heating mode to heat the immersion liquid to a suitable temperature and improve the charging and discharging efficiency of the battery cell.

[0027] If T_mid ≤ T < T_high, the cell is in a slightly high temperature range. Only the circulation pump is started, and the cooling is not turned on. The circulation is used to distribute the heat from the local high temperature area to the entire system, and the temperature is reduced by natural heat dissipation.

[0028] If T ≥ T_high, the cell is in the high temperature range. Start the circulation pump and turn on the heat exchanger cooling mode to force cooling until the temperature drops below T_mid.

[0029] S4: BMU29 monitors the pressure value P in real time. If P exceeds the safety threshold P_max, it is determined that the pressure inside the chamber is abnormal and may be a precursor to thermal runaway. The pressure relief device is immediately activated to release the pressure and an alarm signal is sent to the external system.

[0030] S5: Fire-fighting linkage. The immersion fluid contains fire inhibitors (such as fluorinated compounds). When BMU29 determines that there is a risk of thermal runaway based on a combination of temperature and pressure data (e.g., the rate of temperature rise exceeds the threshold and the pressure rises sharply), it immediately enters the fire-fighting linkage mode: the circulation pump runs at full speed, rapidly circulating the immersion fluid containing the inhibitor to the surface of all battery cells, covering potential ignition sources and suppressing the occurrence and spread of fire.

[0031] The BMU29 uploads real-time data, alarm information, and system status to the energy storage system controller or the cloud via communication terminal 22, facilitating remote monitoring and operation and maintenance.

[0032] Summary of key technologies Module-level pressure adaptive: Through the elastic pressure regulating plate, the flow channel cross-sectional area is automatically reduced when the cell expands, the flow rate is increased, the heat dissipation is enhanced, and the expansion pressure is released at the same time to protect the cell life.

[0033] Six-sided three-dimensional heat exchange: Through the flow guide assembly and optimized flow channel design, the immersion liquid flows evenly around the battery cell, ensuring heat dissipation from all six sides of the battery cell, and the temperature difference between the battery cells is ≤2℃.

[0034] Intelligent zoned temperature control: Based on multi-threshold temperature zoned control, it features low-temperature heating, medium-temperature circulation, and high-temperature cooling, improving system energy efficiency and cell consistency.

[0035] Integrated fire protection: The immersion liquid contains fire inhibitors, which, combined with air pressure and temperature monitoring, enable early warning of thermal runaway and automatic fire-fighting linkage, preventing the spread of heat.

[0036] Intrinsic safety design: Multiple safety measures, including sealed enclosure, rubber ring seal, redundant sensor monitoring, and pressure relief device, ensure long-term stable operation of the system. Beneficial effects

[0037] Compared with the prior art, the present invention has the following beneficial effects: It achieves uniform heat dissipation on all six sides of the battery cell, with a temperature difference between battery cells ≤2℃, significantly improving temperature consistency; The pressure regulating plate adapts to cell expansion, extending cell cycle life. Multi-threshold intelligent temperature control strategy reduces system energy consumption and improves cycle efficiency; The integrated design of fire protection and thermal management enables early warning and automatic suppression of thermal runaway, preventing the spread of fire; With its compact structure and reliable sealing, it is suitable for large-capacity, high-energy-density energy storage systems.

[0038] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A submersible thermal management system for an energy storage battery pack, characterized in that, include: The battery pack housing is formed by sealing the upper cover (30) of the battery pack and the lower housing (20) of the battery pack. The housing is provided with an inlet port (21) and an outlet port (31). The lower housing (20) is provided with an inlet chamber (27), a lower housing guide groove (26) and at least one battery module cavity (25), and a battery module (10) is provided in the battery module cavity (25). The battery module (10) is composed of alternating layers of battery cells (11), current guiding assembly (12), and pressure regulating plate (13), with end plates (14) at both ends and fixed by locking strips (17); The flow guiding assembly (12) and the pressure regulating plate (13) form multiple flow channels (100) for guiding the immersion liquid to flow around the battery cell (11); The lower housing (20) has a liquid inlet chamber (27) at the front end, which is connected to the liquid inlet port (21) and is connected to the battery module cavity (25) via the lower housing guide groove (26); The inner side of the top cover (30) is provided with a guide groove (32) and a liquid outlet chamber (33). The guide groove (32) is connected to the flow channel (100) of the guide assembly (12), and the liquid outlet chamber (33) is connected to the liquid outlet port (31) to form a complete immersion liquid circulation channel. The battery module (10) is also provided with a pressure regulating plate (13). The pressure regulating plate (13) is configured in conjunction with the flow guide assembly (12) and can be compressed when the cell (11) expands, thereby reducing the cross-sectional area of ​​the flow channel, increasing the local flow velocity, and enhancing the heat dissipation capacity. The top cover (30) is equipped with a temperature sensor (34) and a pressure sensor (35) for monitoring the temperature and pressure inside the box; The lower housing (20) is equipped with a BMU (29) at the front end, which is electrically connected to a temperature sensor (34) and a pressure sensor (35) for collecting sensor data and controlling the operation of the circulating pump and heat exchanger.

2. The immersion thermal management system for an energy storage battery pack according to claim 1, characterized in that: The pressure regulating plate (13) is made of an elastic material, and the flow guiding assembly (12) is made of a rigid material, possessing insulation properties and structural strength.

3. The immersion thermal management system for an energy storage battery pack according to claim 1, characterized in that: The FPC fixing plastic part (18) is provided with flow holes (200) that are connected to the flow channels (100) corresponding to the flow guide assembly (12) to guide the immersion liquid to be evenly distributed around the battery cell (11).

4. The immersion thermal management system for an energy storage battery pack according to claim 1, characterized in that: The battery module (10) is also equipped with a flexible FPC (15), a busbar (16), and a signal acquisition terminal (19) for electrical connection and signal acquisition of the battery cells.

5. The immersion thermal management system for an energy storage battery pack according to claim 1, characterized in that: The front end of the lower housing (20) is also provided with a BMU fixing bracket (28), on which a BMU (29) is installed; the front panel of the lower housing (20) is provided with a power port (22) and a communication terminal (23) for external energy transmission and communication.

6. The immersion thermal management system for an energy storage battery pack according to claim 1, characterized in that: A rubber ring (24) is provided between the upper cover (30) and the lower box (20) to achieve a seal.

7. The immersion thermal management system for an energy storage battery pack according to claim 1, characterized in that: The immersion solution contains fire inhibitors.

8. A method for immersion thermal management control of an energy storage battery pack based on the system described in any one of claims 1-7, characterized in that, Includes the following steps: BMU (29) acquires the immersion liquid temperature monitored by temperature sensor (35) in real time, which is equivalent to the cell temperature; BMU(29) compares the collected temperature value with the preset temperature threshold to determine the temperature range; Based on the temperature range, the BMU (29) controls the start-up, shutdown, and operating mode of the circulating pump and heat exchanger to achieve temperature regulation of the battery pack; At the same time, the BMU (29) collects the pressure value of the air pressure sensor (34) in real time. When the pressure exceeds the safety threshold, the pressure relief device is activated and an alarm signal is issued.

9. The control method according to claim 8, characterized in that, The temperature threshold includes a first lower threshold, a first upper threshold, and a second upper threshold, wherein the first lower threshold is the lower limit of the suitable operating temperature of the battery cell, the first upper threshold is the upper limit of the suitable operating temperature of the battery cell, and the second upper threshold is a starting cooling threshold that is higher than the first upper threshold. The step of controlling according to the temperature range includes: When the temperature is below the first lower limit threshold, BMU (29) controls the circulation pump to start and controls the heat exchanger to heat the immersion liquid until the temperature rises to a suitable range; When the temperature is between the first upper limit threshold and the second upper limit threshold, the BMU (29) controls the circulation pump to start, the heat exchanger does not work, and only the heat in the high temperature area is dispersed through circulation; When the temperature exceeds the second upper limit threshold, the BMU (29) controls the circulation pump to start and controls the heat exchanger to cool down until the temperature returns to a suitable range.

10. The control method according to claim 8, characterized in that: When the BMU (29) detects an abnormal increase in pressure or a sharp rise in temperature in the air pressure sensor (34) exceeding the thermal runaway threshold, it determines that there is a risk of thermal runaway and immediately activates the fire-fighting linkage. The immersion liquid containing fire inhibitor is rapidly circulated to the surface of all battery cells through the circulation system to suppress the spread of fire.

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