Battery pack thermal management system and control method

Abstract

This invention relates to the field of battery technology, and more particularly to a battery pack thermal management system, comprising N battery pack pipelines, a main pipeline, a heater, a three-way valve, a liquid storage tank, a primary heat exchanger, a primary insulation box, a vacuum pump, and a valve assembly. Each of the N battery pack pipelines has one end connected to an inlet and the other end connected to an outlet. M battery packs are respectively installed on the N battery pack pipelines. One end of the main pipeline is connected to the inlet, and the other end is a branch port. The heater is used to heat the main pipeline. Port A of the three-way valve is connected to the outlet. One port of the liquid storage tank is connected to the branch port, and the other port is connected to port B of the three-way valve. One port of the primary heat exchanger is connected to the branch port, and the other port is connected to port C of the three-way valve. The port of the primary insulation box is connected to the outlet via a first pipeline. The vacuum pump is connected to the inlet via a suction pipeline. The valve assembly is used to control the opening and closing of the pipelines. This invention also provides a control method applied to the above-mentioned battery pack thermal management system.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a battery pack thermal management system and control method. Background Technology

[0002] Currently, battery pack thermal management mainly involves two methods: air cooling and water cooling. Air cooling systems have a relatively simple construction principle, primarily using a fan to drive airflow and remove heat from the battery cell surface. This method is low-cost and suitable for applications with less stringent thermal management requirements. Water cooling systems primarily use heat exchangers to exchange heat with the coolant, lowering its temperature. A water pump then drives the coolant flow, further removing heat from the battery cell surface. Cooling the cells with coolant offers the advantage of more uniform cooling and is suitable for applications with higher requirements for battery pack thermal management systems. After each battery pack use, the heat exchange medium within the thermal management system still retains some cooling capacity that can be recovered. However, current battery pack thermal management systems lack designs for recovering and utilizing this cooling capacity, resulting in energy waste.

[0003] Therefore, there is an urgent need for a battery pack thermal management system and control method to solve the above problems. Summary of the Invention

[0004] One objective of this invention is to provide a battery pack thermal management system that can avoid energy waste and improve energy utilization.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] A battery pack thermal management system is provided, comprising:

[0007] N battery pack pipelines, each of which is connected at one end to an inlet and at the other end to an outlet, and M battery packs are respectively disposed on the N battery pack pipelines, so that each battery pack pipeline is provided with at least one battery pack.

[0008] The main pipeline has one end connected to the liquid inlet and the other end being a branch port;

[0009] Heater, the heater being used to heat the main pipeline;

[0010] A three-way valve, wherein port A of the three-way valve is connected to the liquid outlet;

[0011] A liquid storage tank, one port of which is connected to the fork inlet and the other port of which is connected to port B of the three-way valve;

[0012] A primary heat exchanger, one port of which is connected to the bifurcation port and the other port of which is connected to port C of the three-way valve;

[0013] A primary insulation box, the port of which is connected to the liquid outlet via a first pipeline;

[0014] A vacuum pump, which is connected to the liquid inlet via a suction pipe;

[0015] The valve assembly includes a first valve, a second valve, a third valve, and a fourth valve. The first valve is disposed on the pipeline between the main pipeline and the inlet, the second valve is disposed on the suction pipeline, the third valve is disposed on the first pipeline, and the fourth valve is disposed on the pipeline between the outlet and port A.

[0016] As a preferred embodiment of the battery pack thermal management system, it also includes a secondary insulation box and a fifth valve. The port of the secondary insulation box is connected to the liquid outlet through a second pipeline, and the fifth valve is installed on the second pipeline.

[0017] As a preferred embodiment of the battery pack thermal management system, it further includes a condenser, a compressor, an expansion valve, and a secondary heat exchanger that are sequentially connected to form a circulation pipeline, wherein the secondary heat exchanger exchanges heat with the primary heat exchanger.

[0018] As a preferred embodiment of the battery pack thermal management system, it also includes a fan that blows air toward the reservoir and / or the condenser.

[0019] As a preferred embodiment of the battery pack thermal management system, a liquid pump is also included, which is located on the main pipeline.

[0020] As a preferred embodiment of the battery pack thermal management system, an expansion tank is also included, which is connected downstream of the liquid pump via a pipeline.

[0021] Another objective of this invention is to provide a control method that can avoid energy waste and improve energy utilization efficiency.

[0022] To achieve this objective, the present invention adopts the following technical solution:

[0023] A control method is provided, applied to the aforementioned battery pack thermal management system, wherein the control method includes the following steps under summer operating conditions:

[0024] S1, Primary Cold Energy Recovery Mode: After the battery system finishes working, close the first and fourth valves, open the second and third valves, and start the vacuum pump to pressurize the heat exchange medium in the battery pack pipeline into the primary insulation box.

[0025] S2, Secondary Cooling Recovery Mode: Close the third valve, open the fifth valve, and start the vacuum pump to pressurize the heat exchange medium in the secondary insulation box into the battery pack pipeline. Close the second valve and the fifth valve, open the first valve and the fourth valve, connect the A and C ports of the three-way valve, start the liquid pump for a preset time T1, close the first valve and the fourth valve, open the second valve and the fifth valve, start the vacuum pump to pressurize the heat exchange medium in the battery pack pipeline into the secondary insulation box, and close the vacuum pump, the second valve, and the fifth valve.

[0026] S3, Cooling application mode: Determine whether the temperature of the heat exchange medium in the secondary insulation box is lower than the ambient temperature. If yes, enter the primary cooling application mode. After completion, determine whether the temperature of the heat exchange medium in the primary insulation box is lower than the ambient temperature. If yes, enter the secondary cooling application mode.

[0027] The first-level cooling capacity application mode is as follows: open the second valve and the fifth valve, open the vacuum pump to pressurize the heat exchange medium in the second-level insulation box into the battery pack pipeline, close the vacuum pump for a preset time T2, open the vacuum pump to pressurize the heat exchange medium in the battery pack pipeline into the second-level insulation box, and close the vacuum pump, the second valve and the fifth valve.

[0028] The secondary cooling application mode involves opening the second valve, the third valve, and the vacuum pump to pressurize the heat exchange medium in the primary insulation box into the battery pack pipeline.

[0029] As a preferred embodiment of the control method, the control method under winter operating conditions includes the following steps:

[0030] S01, Primary heat recovery mode: After the battery system finishes working, close the first valve and the fourth valve, open the second valve and the third valve, and start the vacuum pump to pressurize the heat exchange medium in the battery pack pipeline into the primary insulation box.

[0031] S02, Secondary Heat Recovery Mode: Close the third valve, open the fifth valve, and start the vacuum pump to pressurize the heat exchange medium in the secondary insulation box into the battery pack pipeline. Close the second valve and the fifth valve, open the first valve and the fourth valve, connect the A and B ports of the three-way valve, start the liquid pump for a preset time T3, close the first valve and the fourth valve, open the second valve and the fifth valve, start the vacuum pump to pressurize the heat exchange medium in the battery pack pipeline into the secondary insulation box, and close the vacuum pump, the second valve, and the fifth valve.

[0032] S03, Heat application mode: Determine whether the temperature of the heat exchange medium in the secondary insulation box is higher than the ambient temperature. If yes, enter the primary heat application mode. After completion, determine whether the temperature of the heat exchange medium in the primary insulation box is higher than the ambient temperature. If yes, enter the secondary heat application mode.

[0033] The first-level heat application mode is as follows: the second valve and the fifth valve are opened, the vacuum pump is opened to pressurize the heat exchange medium in the second-level insulation box into the battery pack pipeline, the vacuum pump is closed for a preset time T4, the vacuum pump is opened to pressurize the heat exchange medium in the battery pack pipeline into the second-level insulation box, and the vacuum pump, the second valve and the fifth valve are closed.

[0034] The secondary heat application mode involves opening the second valve, the third valve, and the vacuum pump to pressurize the heat exchange medium in the primary insulation box into the battery pack pipeline.

[0035] As a preferred embodiment of the control method, the control method further includes the following for summer operating conditions:

[0036] S001, Level 1 Cooling Mode: When the battery system is working, if it is determined that the temperature of any battery pack is higher than the upper limit of the critical temperature, the A port and B port of the three-way valve are connected, and the liquid pump is started for a preset time T01.

[0037] S002, Secondary cooling mode: When the temperature of the battery pack is still higher than the upper limit of the critical temperature, the fan is turned on to accelerate the airflow outside the liquid storage tank and maintain it for a preset time T02.

[0038] S003, Three-stage cooling mode: When the temperature of the battery pack is still higher than the upper limit of the critical temperature, the compressor is turned on and the three-way valve is switched to connect port A and port C.

[0039] As a preferred embodiment of the control method, the control method further includes the following for winter operating conditions:

[0040] Heating mode: When the temperature of the battery pack is lower than the lower limit of the critical temperature, the A port and B port of the three-way valve are connected to turn on the heater.

[0041] The beneficial effects of this invention are:

[0042] This invention provides a battery pack thermal management system, including N battery pack pipelines, a main pipeline, a heater, a three-way valve, a liquid storage tank, a primary heat exchanger, a primary insulation box, a vacuum pump, and a valve assembly. Each of the N battery pack pipelines has one end connected to an inlet and the other end connected to an outlet. M battery packs are respectively installed on the N battery pack pipelines, ensuring that each battery pack pipeline has at least one battery pack installed. One end of the main pipeline is connected to the inlet, and the other end is a branch port. The heater is used to heat the main pipeline. Port A of the three-way valve is connected to the outlet. One port of the liquid storage tank is connected to the branch port, and the other port is connected to port B of the three-way valve. One port of the primary heat exchanger is connected to the branch port, and the other port is connected to port C of the three-way valve. The primary insulation tank is connected to the liquid outlet via a first pipeline, and the vacuum pump is connected to the liquid inlet via a suction pipeline. When the battery pack system stops working, the vacuum pump is turned on to force the heat exchange medium with usable cold or heat in the battery pack pipeline into the primary insulation tank for storage. When the battery pack resumes operation, the vacuum pump is turned on to force the heat exchange medium in the insulation tank into the battery pack pipeline, thus realizing the storage and application of the cold or heat carried by this heat exchange medium. The valve group includes a first valve, a second valve, a third valve, and a fourth valve. The first valve is located on the pipeline between the main pipeline and the liquid inlet, the second valve is located on the suction pipeline, the third valve is located on the first pipeline, and the fourth valve is located on the pipeline between the liquid outlet and port A, to control the opening and closing of the pipelines. This battery pack thermal management system can store and utilize surplus cold or heat, thereby avoiding energy waste and improving energy utilization efficiency.

[0043] This invention provides a control method applied to the aforementioned battery pack thermal management system. The control method, under summer operating conditions, includes the following steps: S1, Primary Cooling Recovery Mode: After the battery system finishes operating, close the first and fourth valves, open the second and third valves, and start the vacuum pump to pressurize the heat exchange medium in the battery pack pipeline into the primary insulation box; S2, Secondary Cooling Recovery Mode: close the third valve, open the fifth valve, start the vacuum pump to pressurize the heat exchange medium in the secondary insulation box into the battery pack pipeline, close the second and fifth valves, open the first and fourth valves, connect the A and C ports of the three-way valve, start the liquid pump for a preset time T1, close the first and fourth valves, open the second and fifth valves, and start the vacuum pump to pressurize the heat exchange medium in the battery pack pipeline into the secondary insulation box. Insulation box, close the vacuum pump, second valve, and fifth valve; S3, Cooling application mode: Determine if the temperature of the heat exchange medium in the secondary insulation box is lower than the ambient temperature. If yes, enter the primary cooling application mode. After completion, determine if the temperature of the heat exchange medium in the primary insulation box is lower than the ambient temperature. If yes, enter the secondary cooling application mode; Primary cooling application mode: Open the second and fifth valves, turn on the vacuum pump to pressurize the heat exchange medium in the secondary insulation box into the battery pack pipeline, turn off the vacuum pump for a preset time T2, turn on the vacuum pump to pressurize the heat exchange medium in the battery pack pipeline into the secondary insulation box, and turn off the vacuum pump, second valve, and fifth valve; Secondary cooling application mode: Open the second and third valves and the vacuum pump to pressurize the heat exchange medium in the primary insulation box into the battery pack pipeline.

[0044] By using the primary and secondary cold energy recovery modes, the remaining cold energy in the battery pack thermal management system can be recovered and stored after the battery system has finished working. This cold energy can then be utilized when the battery system is turned on again, thereby avoiding energy waste and improving energy efficiency. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the battery pack thermal management system provided in an embodiment of the present invention;

[0046] Figure 2 This is a flowchart illustrating the control method provided in an embodiment of the present invention.

[0047] In the picture:

[0048] 1. Battery pack piping; 2. Main piping; 3. Heater;

[0049] 4. Three-way valve; 401, Port A; 402, Port B; 403, Port C;

[0050] 5. Liquid storage tank; 6. Primary heat exchanger; 7. Primary insulation box; 8. First pipeline; 9. Vacuum pump; 10. Suction pipeline; 11. First valve; 12. Second valve; 13. Third valve; 14. Fourth valve; 15. Secondary insulation box; 16. Second pipeline; 17. Fifth valve; 18. Condenser; 19. Compressor; 20. Expansion valve; 21. Secondary heat exchanger; 22. Fan; 23. Liquid pump; 24. Expansion vessel;

[0051] 101. Liquid inlet; 102. Liquid outlet; 103. Fork inlet;

[0052] 900, battery pack. Detailed Implementation

[0053] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings, not all of them.

[0054] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0055] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0056] like Figure 1As shown, the battery pack thermal management system of this embodiment includes N battery pack pipelines 1, a main pipeline 2, a heater 3, a three-way valve 4, a liquid storage tank 5, a primary heat exchanger 6, a primary insulation box 7, a vacuum pump 9, and a valve assembly. Each of the N battery pack pipelines 1 is connected at one end to an inlet 101 and at the other end to an outlet 102. M battery packs 900 are respectively installed on the N battery pack pipelines 1, ensuring that each battery pack pipeline 1 has at least one battery pack 900. The temperature of the battery pack 900 is regulated by the heat exchange medium within the battery pack pipeline 1. One end of the main pipeline 2 is connected to the inlet 101, and the other end is a branch port 103. The heater 3 is used to heat the main pipeline 2 to increase the temperature of the battery packs 900 in winter conditions, ensuring the normal start-up of the battery packs 900. Port A 401 of the three-way valve 4 is connected to the liquid outlet 102. One port of the liquid storage tank 5 is connected to the bifurcation port 103, and the other port is connected to port B 402 of the three-way valve 4. One port of the primary heat exchanger 6 is connected to the bifurcation port 103, and the other port is connected to port C 403 of the three-way valve 4. When ports A 401 and B 402 of the three-way valve 4 are connected, the heat exchange medium circulates through the liquid storage tank 5, thereby reducing the temperature of the heat exchange medium. When ports A 401 and C 403 of the three-way valve 4 are connected, the heat exchange medium circulates through the primary heat exchanger 6, thereby further reducing the temperature.

[0057] The port of the primary insulation box 7 is connected to the liquid outlet 102 via the first pipeline 8, and the vacuum pump 9 is connected to the liquid inlet 101 via the suction pipeline 10. When the battery pack 900 system stops working, turning on the vacuum pump 9 will pressurize the heat exchange medium with usable cold or heat in the battery pack pipeline 1 into the primary insulation box 7 for storage. When the battery pack 900 starts working again, the vacuum pump 9 will be turned on to pressurize the heat exchange medium in the insulation box into the battery pack pipeline 1, thus realizing the storage and application of the cold or heat carried by this heat exchange medium. The valve group includes a first valve 11, a second valve 12, a third valve 13, and a fourth valve 14. The first valve 11 is installed on the pipeline between the main pipeline 2 and the liquid inlet 101, the second valve 12 is installed on the suction pipeline 10, the third valve 13 is installed on the first pipeline 8, and the fourth valve 14 is installed on the pipeline between the liquid outlet 102 and port A 401 to control the opening and closing of the pipeline. This battery pack thermal management system can store and utilize excess cold or heat, thereby avoiding energy waste and improving energy efficiency.

[0058] To further improve the efficiency of recovering residual cold or heat, preferably, the battery pack thermal management system also includes a secondary insulation box 15 and a fifth valve 17. The port of the secondary insulation box 15 is connected to the liquid outlet 102 through a second pipeline 16, and the fifth valve 17 is installed on the second pipeline 16. The working principle of the secondary insulation box 15 will be described in detail below.

[0059] To cool the primary heat exchanger 6 and improve its cooling capacity for the heat exchange medium, the battery pack thermal management system preferably includes a condenser 18, a compressor 19, an expansion valve 20, and a secondary heat exchanger 21 connected in sequence to form a circulation pipeline. The secondary heat exchanger 21 exchanges heat with the primary heat exchanger 6. The compressor 19 compresses the refrigerant inside, turning it into a high-temperature, high-pressure liquid. After being cooled by the condenser 18, it becomes a low-temperature, high-pressure liquid. After passing through the expansion valve 20, the high pressure becomes low pressure, and the liquid becomes mist-like droplets, undergoing a vaporization process within the secondary heat exchanger 21. This vaporization process requires heat absorption, meaning it absorbs heat from the heat exchange medium in the primary heat exchanger 6, thus lowering the temperature of the heat exchange medium and improving its cooling capacity for the battery pack 900.

[0060] Preferably, the battery pack thermal management system further includes a fan 22 that blows air toward the liquid storage tank 5 and / or the condenser 18 to increase the airflow velocity in the environment where the liquid storage tank 5 and / or the condenser 18 is located, thereby increasing the efficiency of heat exchange between the liquid storage tank 5 and / or the condenser 18 and the air and accelerating cooling.

[0061] Preferably, the battery pack thermal management system further includes a liquid pump 23, which is disposed on the main pipeline 2 to provide power for the flow of the heat exchange medium.

[0062] Preferably, the battery pack thermal management system further includes an expansion tank 24, which is connected downstream of the liquid pump 23 via a pipeline to ensure the stability of the hydraulic pressure in the main pipeline 2.

[0063] Preferably, in this embodiment, to ensure a more balanced cooling or heating effect on each battery pack 900, one battery pack 900 is provided on each battery pack pipeline 1. Of course, in other embodiments, two or more battery packs 900 can also be provided on one battery pack pipeline 1 to adapt to actual application scenarios.

[0064] To facilitate temperature monitoring, the battery pack thermal management system preferably includes a first temperature sensor (not shown in the figure) for measuring the liquid temperature within the battery pack pipeline 1. Preferably, the battery pack thermal management system also includes a second temperature sensor (not shown in the figure) for measuring the ambient temperature.

[0065] To ensure a balanced flow of heat exchange medium in each battery pack pipeline 1, the battery pack thermal management system preferably includes a flow divider (not shown in the figure), which is located at the liquid inlet 101 to ensure that the flow of heat exchange medium in multiple battery pack pipelines 1 is consistent.

[0066] like Figure 2As shown, this embodiment also provides a control method applied to the aforementioned battery pack thermal management system. This control method can recover and utilize the remaining cooling capacity within the battery pack thermal management system under summer operating conditions, specifically including the following steps:

[0067] S1, Primary Cooling Recovery Mode: Since the ambient temperature in summer is higher than the operating temperature of the battery pack 900, the temperature of the heat exchange medium in the battery pack thermal management system is lower than the ambient temperature. After the battery system finishes operating, the heat exchange medium in the battery pack thermal management system has residual cooling capacity that can be recovered. First, close the first valve 11 and the fourth valve 14, open the second valve 12 and the third valve 13, and then turn on the vacuum pump 9. Under the action of air pressure, the heat exchange medium in the battery pack pipeline 1 is forced into the primary insulation box 7 to store this portion of the heat exchange medium with residual cooling capacity. At this time, the battery pack pipeline 1 is filled with air. After the operation is completed, turn off the vacuum pump 9.

[0068] S2, Secondary Cooling Recovery Mode: At this time, the temperature of the battery pack 900 itself is still lower than the ambient temperature, and the heat exchange medium in the main pipeline 2 and the pipeline passing through the primary heat exchanger 6 still has a certain amount of cooling capacity. Close the third valve 13, open the fifth valve 17, and start the vacuum pump 9 to rotate in reverse to force the heat exchange medium in the secondary insulation box 15 into the battery pack pipeline 1. Then close the vacuum pump 9, the second valve 12, and the fifth valve 17, open the first valve 11 and the fourth valve 14, connect the A port 401 and the C port 403 of the three-way valve 4, and start the liquid pump 23 for a preset time T1 so that the heat exchange medium injected from the secondary insulation box 15 absorbs the cooling capacity of the battery pack 900 and the primary heat exchanger 6, and exchanges heat with the heat exchange medium in the original pipeline. The preset time T1 can be set to the time from the start until the temperature of the heat exchange medium no longer changes. At this time, the liquid pump 23 stops working, the first valve 11 and the fourth valve 14 are closed, the second valve 12 and the fifth valve 17 are opened, and the vacuum pump 9 is turned on to pressurize the heat exchange medium in the battery pack pipeline 1 into the secondary insulation box 15 to store this part of the cold energy. Then the vacuum pump 9, the second valve 12 and the fifth valve 17 are closed.

[0069] S3, Cooling Application Mode: When the battery system needs to be restarted after being idle for a period of time, the battery system temperature is the same as the ambient temperature. In order to ensure that the battery system can work normally, it is necessary to cool the battery system.

[0070] Since the liquid temperature in the primary insulation box 7 is lower than that in the secondary insulation box 15, the cooling capacity stored in the secondary insulation box 15 can be utilized first. First, it is determined whether the temperature of the heat exchange medium in the secondary insulation box 15 is lower than the ambient temperature. If so, the primary cooling capacity application mode is entered to use the heat exchange medium in the secondary insulation box 15 to cool the battery pack 900. After completion, it is then determined whether the temperature of the heat exchange medium in the primary insulation box 7 is lower than the ambient temperature. If so, the secondary cooling capacity application mode is entered to utilize the cooling capacity stored in the secondary insulation box 15. If the temperature of the heat exchange medium in the secondary insulation box 15 is equal to the ambient temperature, or the temperature difference between them is too small, it is directly determined whether the temperature of the heat exchange medium in the primary insulation box 7 is lower than the ambient temperature. If so, the secondary cooling capacity application mode is entered; otherwise, the normal cooling mode is entered directly.

[0071] Primary cooling capacity application mode: Open the second valve 12 and the fifth valve 17, and start the vacuum pump 9 to force the heat exchange medium in the secondary insulation box 15 into the battery pack pipeline 1. Turn off the vacuum pump 9 for a preset time T2. During this time, the heat exchange medium continuously absorbs heat from the battery pack 900, causing the temperature of the battery pack 900 to continuously decrease. The preset time T2 can be set to the point when the liquid temperature in the battery pack pipeline 1 no longer changes. Then turn on the vacuum pump 9 to force the heat exchange medium in the battery pack pipeline 1 into the secondary insulation box 15, and turn off the vacuum pump 9, the second valve 12, and the fifth valve 17.

[0072] Secondary cooling capacity application mode: Open the second valve 12, the third valve 13, and the vacuum pump 9 to pressurize the heat exchange medium in the primary insulation box 7 into the battery pack pipeline 1. Once the liquid temperature in the battery pack pipeline 1 stabilizes, the battery system can be turned on, and then normal cooling mode will begin.

[0073] Preferably, this control method can recover and utilize the residual heat in the battery pack thermal management system under winter operating conditions, specifically including the following steps:

[0074] S01, Primary Heat Recovery Mode: Since the ambient temperature in winter is lower than the operating temperature of the battery pack 900, the temperature of the heat exchange medium in the battery pack thermal management system is higher than the ambient temperature to heat the battery pack 900. After the battery system finishes operating, the heat exchange medium in the battery pack thermal management system has residual heat that can be recovered. First, after the battery system finishes operating, close the first valve 11 and the fourth valve 14, open the second valve 12 and the third valve 13, and start the vacuum pump 9 to pressurize the heat exchange medium in the battery pack pipeline 1 into the primary insulation box 7.

[0075] S02, Secondary Heat Recovery Mode: At this time, the temperature of the battery pack 900 itself is still higher than the ambient temperature, and the heat exchange medium in the main pipeline 2 and the pipeline passing through the storage tank 5 still has a certain amount of heat. Close the third valve 13, open the fifth valve 17, and start the vacuum pump 9 to force the heat exchange medium in the secondary insulation box 15 into the battery pack pipeline 1. Close the second valve 12 and the fifth valve 17, open the first valve 11 and the fourth valve 14, connect the A port 401 and the B port 402 of the three-way valve 4, and start the liquid pump 23 for a preset time T3 to allow the heat exchange medium to circulate and continuously increase the temperature of the injected heat exchange medium to absorb and store some heat. The preset time T3 can be set to the moment when the liquid temperature in the battery pack pipeline 1 tends to stabilize, close the first valve 11 and the fourth valve 14, open the second valve 12 and the fifth valve 17, start the vacuum pump 9 to force the heat exchange medium in the battery pack pipeline 1 into the secondary insulation box 15 for storage, and close the vacuum pump 9, the second valve 12, and the fifth valve 17.

[0076] S03, Heat Application Mode: When the battery system needs to be restarted after a period of inactivity, since the battery system temperature is the same as the ambient temperature, it needs to be heated to ensure normal operation. First, it checks if the temperature of the heat exchange medium in the secondary insulation box 15 is higher than the ambient temperature. If so, it enters the primary heat application mode to heat the battery pack 900 using the heat exchange medium in the secondary insulation box 15. After heating, it checks if the temperature of the heat exchange medium in the primary insulation box 7 is higher than the ambient temperature. If so, it enters the secondary heat application mode to utilize the heat stored in the secondary insulation box 15. If the temperature of the heat exchange medium in the secondary insulation box 15 is equal to the ambient temperature, or the temperature difference is too small, it directly checks if the temperature of the heat exchange medium in the primary insulation box 7 is lower than the ambient temperature. If so, it enters the secondary heat application mode; otherwise, it directly enters the normal heating mode.

[0077] Primary heat application mode: Open the second valve 12 and the fifth valve 17, and start the vacuum pump 9 to force the heat exchange medium in the secondary insulation box 15 into the battery pack pipeline 1. Turn off the vacuum pump 9 for a preset time T4. During this time, the heat exchange medium continuously absorbs the cold energy from the battery pack 900, causing the temperature of the battery pack 900 to continuously rise. The preset time T4 can be set to the point when the liquid temperature in the battery pack pipeline 1 no longer changes. Turn on the vacuum pump 9 to force the heat exchange medium in the battery pack pipeline 1 into the secondary insulation box 15, and then turn off the vacuum pump 9, the second valve 12, and the fifth valve 17.

[0078] Secondary heat application mode: Open the second valve 12, the third valve 13, and the vacuum pump 9 to pressurize the heat exchange medium in the primary insulation box 7 into the battery pack pipeline 1. Once the liquid temperature in the battery pack pipeline 1 stabilizes, the battery system can be turned on, and then it will enter the normal heating mode.

[0079] Preferably, the normal cooling mode of the control method under summer operating conditions includes the following steps:

[0080] S001, Level 1 Cooling Mode: When the battery system is working, if the temperature of any battery pack 900 is found to be higher than the upper limit of the critical temperature, the A port 401 and B port 402 of the three-way valve 4 are connected, and the liquid pump 23 is turned on for a preset time T01. The heat exchange medium is used to absorb the heat of the battery pack 900 through circulation, and the heat is dissipated to the environment in the subsequent flow process.

[0081] S002, Secondary Cooling Mode: When the temperature of the battery pack 900 is still higher than the upper limit of the critical temperature, the fan 22 is turned on to accelerate the airflow outside the liquid storage tank 5, so as to reduce the temperature of the heat exchange medium inside the liquid storage tank 5, thereby improving the cooling effect of the battery pack 900 and maintaining it for a preset time T02.

[0082] S003, Three-stage cooling mode: When the temperature of the battery pack 900 is still higher than the upper limit of the critical temperature, the compressor 19 is turned on, and the three-way valve 4 is switched to connect port A 401 and port C 403. That is, the temperature of the heat exchange medium is reduced by using the first-stage heat exchanger 6 to improve the cooling effect on the battery pack 900.

[0083] Preferably, the normal heating mode of the control method under winter conditions is as follows: when the temperature of the battery pack 900 is lower than the lower limit of the critical temperature, the A port 401 and B port 402 of the three-way valve 4 are connected, the heater 3 is turned on, and the heater 3 is used to heat the heat exchange medium in the main pipeline 2, thereby increasing the temperature of the battery pack 900.

[0084] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A battery pack thermal management system, characterized in that, include: N battery pack pipelines (1), each of the N battery pack pipelines (1) is connected at one end to the liquid inlet (101) and at the other end to the liquid outlet (102), and M battery packs (900) are respectively arranged on the N battery pack pipelines (1) so that each battery pack pipeline (1) is provided with at least one battery pack (900); Main pipeline (2), one end of which is connected to the liquid inlet (101), and the other end is a branch port (103); Heater (3), said heater (3) is used to heat the main pipeline (2); A three-way valve (4), wherein port A (401) of the three-way valve (4) is connected to the liquid outlet (102); A liquid storage tank (5), one port of which is connected to the bifurcation port (103) and the other port is connected to the B port (402) of the three-way valve (4); A primary heat exchanger (6) has one port connected to the bifurcation port (103) and the other port connected to port C (403) of the three-way valve (4). A primary insulation box (7), the port of which is connected to the liquid outlet (102) through a first pipeline (8); A vacuum pump (9) is connected to the liquid inlet (101) via a suction pipe (10); The valve assembly includes a first valve (11), a second valve (12), a third valve (13), and a fourth valve (14). The first valve (11) is disposed on the pipeline between the main pipeline (2) and the inlet (101). The second valve (12) is disposed on the suction pipeline (10). The third valve (13) is disposed on the first pipeline (8). The fourth valve (14) is disposed on the pipeline between the outlet (102) and the A port (401). It also includes a secondary insulation box (15) and a fifth valve (17). The port of the secondary insulation box (15) is connected to the liquid outlet (102) through a second pipeline (16), and the fifth valve (17) is installed on the second pipeline (16).

2. The battery pack thermal management system according to claim 1, characterized in that, It also includes a condenser (18), a compressor (19), an expansion valve (20) and a secondary heat exchanger (21) that are connected in sequence to form a circulation pipeline, wherein the secondary heat exchanger (21) exchanges heat with the primary heat exchanger (6).

3. The battery pack thermal management system according to claim 2, characterized in that, It also includes a fan (22) that blows air toward the liquid storage tank (5) and / or the condenser (18).

4. The battery pack thermal management system according to claim 1, characterized in that, It also includes a liquid pump (23), which is mounted on the main pipeline (2).

5. The battery pack thermal management system according to claim 4, characterized in that, It also includes an expansion vessel (24), which is connected downstream of the liquid pump (23) via a pipeline.

6. A control method, characterized in that, The control method, applied to the battery pack thermal management system as described in any one of claims 1-5, includes the following steps under summer operating conditions: S1, First-level cold energy recovery mode: After the battery system finishes working, close the first valve (11) and the fourth valve (14), open the second valve (12) and the third valve (13), and start the vacuum pump (9) to press the heat exchange medium in the battery pack pipeline (1) into the first-level heat preservation box (7). S2, Secondary Cooling Recovery Mode: Close the third valve (13), open the fifth valve (17), and turn on the vacuum pump (9) to press the heat exchange medium in the secondary insulation box (15) into the battery pack pipeline (1). Close the second valve (12) and the fifth valve (17), open the first valve (11) and the fourth valve (14), connect the A port (401) and C port (403) of the three-way valve (4), turn on the liquid pump (23) for a preset time T1, close the first valve (11) and the fourth valve (14), open the second valve (12) and the fifth valve (17), turn on the vacuum pump (9) to press the heat exchange medium in the battery pack pipeline (1) into the secondary insulation box (15), and close the vacuum pump (9), the second valve (12) and the fifth valve (17). S3, Cooling application mode: Determine whether the temperature of the heat exchange medium in the secondary insulation box (15) is lower than the ambient temperature. If yes, enter the first-level cooling application mode. After completion, determine whether the temperature of the heat exchange medium in the first-level insulation box (7) is lower than the ambient temperature. If yes, enter the second-level cooling application mode. The first-level cooling capacity application mode is as follows: open the second valve (12) and the fifth valve (17), open the vacuum pump (9) to press the heat exchange medium in the second-level insulation box (15) into the battery pack pipeline (1), close the vacuum pump (9) for a preset time T2, open the vacuum pump (9) to press the heat exchange medium in the battery pack pipeline (1) into the second-level insulation box (15), and close the vacuum pump (9), the second valve (12) and the fifth valve (17); The secondary cooling application mode: the second valve (12), the third valve (13) and the vacuum pump (9) are opened to pressurize the heat exchange medium in the primary insulation box (7) into the battery pack pipeline (1).

7. The control method according to claim 6, characterized in that, The control method under winter operating conditions includes the following steps: S01, First-level heat recovery mode: After the battery system finishes working, close the first valve (11) and the fourth valve (14), open the second valve (12) and the third valve (13), and start the vacuum pump (9) to press the heat exchange medium in the battery pack pipeline (1) into the first-level heat preservation box (7). S02, Secondary heat recovery mode: Close the third valve (13), open the fifth valve (17), and turn on the vacuum pump (9) to press the heat exchange medium in the secondary insulation box (15) into the battery pack pipeline (1). Close the second valve (12) and the fifth valve (17), open the first valve (11) and the fourth valve (14), connect the A port (401) and B port (402) of the three-way valve (4), turn on the liquid pump (23) for a preset time T3, close the first valve (11) and the fourth valve (14), open the second valve (12) and the fifth valve (17), turn on the vacuum pump (9) to press the heat exchange medium in the battery pack pipeline (1) into the secondary insulation box (15), and close the vacuum pump (9), the second valve (12) and the fifth valve (17). S03, Heat application mode: Determine whether the temperature of the heat exchange medium in the secondary insulation box (15) is higher than the ambient temperature. If yes, enter the first-level heat application mode. After completion, determine whether the temperature of the heat exchange medium in the first-level insulation box (7) is higher than the ambient temperature. If yes, enter the second-level heat application mode. The first-level heat application mode is as follows: open the second valve (12) and the fifth valve (17), open the vacuum pump (9) to press the heat exchange medium in the second-level insulation box (15) into the battery pack pipeline (1), close the vacuum pump (9) for a preset time T4, open the vacuum pump (9) to press the heat exchange medium in the battery pack pipeline (1) into the second-level insulation box (15), and close the vacuum pump (9), the second valve (12) and the fifth valve (17); The secondary heat application mode: the second valve (12), the third valve (13) and the vacuum pump (9) are opened to pressurize the heat exchange medium in the primary insulation box (7) into the battery pack pipeline (1).

8. The control method according to claim 6, characterized in that, The control method also includes the following under summer operating conditions: S001, Level 1 Cooling Mode: When the battery system is working, if it is determined that the temperature of any battery pack (900) is higher than the upper limit of the critical temperature, the A port (401) and B port (402) of the three-way valve (4) are connected, and the liquid pump (23) is turned on for a preset time T01. S002, Secondary cooling mode: When the temperature of the battery pack (900) is still higher than the upper limit of the critical temperature, the fan (22) is turned on to accelerate the airflow outside the liquid storage tank (5) and maintain it for a preset time T02. S003, Three-level cooling mode: When the temperature of the battery pack (900) is still higher than the upper limit of the critical temperature, the compressor (19) is turned on and the three-way valve (4) is switched to connect port A (401) and port C (403).

9. The control method according to claim 6, characterized in that, The control method also includes the following for winter operating conditions: Heating mode: When the temperature of the battery pack (900) is lower than the lower limit of the critical temperature, the A port (401) and B port (402) of the three-way valve (4) are connected to turn on the heater (3).

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