A battery pack thermal management test system

Abstract

The present invention belongs to the technical field of battery testing, and discloses a battery pack thermal management test system, which includes a variable frequency compressor, a condenser, a first heat exchange unit, a second heat exchange unit, a gas-liquid separator, a variable frequency pump, a first test pipeline and a second test pipeline. A variable frequency fan is correspondingly arranged on the condenser, the first heat exchange unit has a first heat exchange tube and a second heat exchange tube, the second heat exchange unit has a third heat exchange tube and a fourth heat exchange tube, the first heat exchange tube and the third heat exchange tube are used to circulate refrigerant, and the second heat exchange tube and the fourth heat exchange tube are used to circulate heat exchange medium; a first control valve is arranged on the first test pipeline, and a second control valve is arranged on the second test pipeline. The battery pack thermal management test system is compatible with various types of battery pack tests, meets the test requirements of various types of battery packs, and can recycle the refrigerant after the test is completed to avoid residual refrigerant in the battery pack and ensure that the next test is carried out normally.

Description

Technical Field

[0001] The present invention relates to the technical field of battery testing, and in particular to a battery pack thermal management testing system. Background Art

[0002] At present, the new energy vehicle industry is an emerging industry. The use of ethylene glycol aqueous solution as a refrigerant to cool or heat the battery pack or cold plate of new energy vehicles is still the mainstream method. The related research and application of direct cooling and heating of battery packs or cold plates using Freon refrigerants is still in the initial stage. It is particularly important to invent a device that can simulate the operating boundary of the battery in the whole vehicle state through interface control parameters, thereby simulating and testing the performance of battery cooling and direct heating, and doing preliminary debugging for vehicle installation matching.

[0003] At present, thermal management test systems need to face several technical problems:

[0004] 1. Since the battery packs installed on the vehicle have different capacities, the battery pack PACK processes and cold plate flow channel structures are different, the test system must be able to meet the test requirements of various battery packs at the same time;

[0005] 2. During the test, Freon circulates directly inside the cold plate of the battery pack. After the test, there is some refrigerant in the cold plate flow channel. The refrigerant must be recovered to the test equipment to ensure that the next test can proceed normally. Summary of the invention

[0006] The purpose of the present invention is to provide a battery pack thermal management test system, which is compatible with various types of battery pack tests, meets the test requirements of various types of battery packs, and can recover the refrigerant after the test to avoid residual refrigerant in the battery pack and ensure that the next test is carried out normally.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] The present invention discloses a battery pack thermal management test system, comprising a variable frequency compressor, a condenser, a first heat exchange unit, a second heat exchange unit, a gas-liquid separator, a variable frequency pump, a first test pipeline and a second test pipeline, wherein a variable frequency fan is correspondingly arranged on the condenser, the first heat exchange unit has a first heat exchange tube and a second heat exchange tube, the second heat exchange unit has a third heat exchange tube and a fourth heat exchange tube, the first heat exchange tube and the third heat exchange tube are used for circulating refrigerant, and the second heat exchange tube and the fourth heat exchange tube are used for circulating heat exchange medium; a first control valve is arranged on the first test pipeline, a second control valve is arranged on the second test pipeline, and a battery pack is replaceably installed between the first test pipeline and the second test pipeline; the battery pack thermal management test system has a direct cooling test mode, a direct heating test mode and a refrigerant recovery mode; wherein: in the direct cooling test mode, the refrigerant flows out from the variable frequency compressor and passes through the condenser, the first heat exchange tube in sequence, When the refrigerant reaches the gas-liquid separator, the liquid refrigerant, driven by the variable frequency pump, flows from the liquid outlet of the gas-liquid separator through the first test pipeline, the battery pack and the second test pipeline into the third heat exchange tube, and the gaseous refrigerant flows from the gas outlet of the gas-liquid separator into the third heat exchange tube. The two refrigerants merge in the third heat exchange tube and return to the variable frequency compressor. In the direct heating test mode, the refrigerant flows out of the variable frequency compressor, passes through the first heat exchange tube, the second test pipeline, the battery pack and the first test pipeline, and enters the gas-liquid separator. All the refrigerant, driven by the variable frequency pump, flows from the liquid outlet of the gas-liquid separator into the third heat exchange tube, and returns to the variable frequency compressor after heat exchange with the heat exchange medium. In the refrigerant recovery mode, the variable frequency pump stops working, and the refrigerant remaining in the battery pack passes through the second test pipeline and the third heat exchange tube and returns to the variable frequency compressor.

[0009] In some embodiments, the battery pack thermal management test system also includes a first temperature sensor, a first pressure transmitter, a second temperature sensor and a second pressure transmitter, the first temperature sensor and the first pressure transmitter are connected to the air outlet of the variable frequency compressor in sequence, and the second pressure transmitter and the second temperature sensor are connected to the air return port of the variable frequency compressor in sequence.

[0010] In some embodiments, the battery pack thermal management test system also includes a first sight glass and a second sight glass, the first sight glass is arranged on the first test pipeline and located upstream of the first control valve, and the second sight glass is arranged on the second test pipeline and located downstream of the second control valve.

[0011] In some embodiments, the battery pack thermal management test system also includes a third sight glass, a third temperature sensor and a third pressure transmitter. At the inlet of the first heat exchange tube, the third sight glass, the third temperature sensor and the third pressure transmitter are arranged in sequence along the refrigerant flow direction.

[0012] In some embodiments, the battery pack thermal management test system also includes an oil separator, the inlet of the oil separator is connected to the air outlet of the variable frequency compressor, the oil return port of the oil separator is connected to the oil recovery port of the variable frequency compressor through an oil return capillary, and the outlet of the oil separator is provided with a first branch pipe and a second branch pipe, the first branch pipe is connected to the first heat exchange tube, the second branch pipe is arranged in parallel with the first branch pipe, and the condenser is installed on the second branch pipe; a third control valve is provided on the first branch pipe, and a fourth control valve is provided on the second branch pipe; the outlet of the oil separator is directly connected to the condenser and one of the first heat exchange tubes in a switchable manner through the third control valve and the fourth control valve.

[0013] In some embodiments, the battery pack thermal management test system also includes a first electric heating tube, a first circulation pump, a second electric heating tube, and a second circulation pump. The first electric heating tube and the second electric heating tube are used to circulate heat exchange medium. The first circulation pump is used to drive the heat exchange medium to circulate in the first electric heating tube and the second heat exchange tube; the second circulation pump is used to drive the heat exchange medium to circulate in the second electric heating tube and the fourth heat exchange tube.

[0014] In some specific embodiments, the battery pack thermal management test system also includes an expansion tank, to which is connected a first liquid replenishment pipeline, a first exhaust pipeline, a second liquid replenishment pipeline, a second exhaust pipeline and a liquid adding pipeline; wherein: the first liquid replenishment pipeline is connected to the first electric heating tube, and a first one-way valve is provided on the first liquid replenishment pipeline; the second liquid replenishment pipeline is connected to the second electric heating tube, and a second one-way valve is provided on the second liquid replenishment pipeline; the first exhaust pipeline and the second exhaust pipeline are respectively connected to the exhaust ports of the first electric heating tube and the second electric heating tube.

[0015] In some embodiments, the refrigerant inlet of the gas-liquid separator is connected to the outlet of the second heat exchange tube through a third branch pipe, the gas outlet of the gas-liquid separator is connected to the second test pipeline through a fourth branch pipe, the liquid outlet of the gas-liquid separator is connected to the first test pipeline through a fifth branch pipe, and the second test pipeline is connected to the inlet of the third heat exchange tube through a sixth branch pipe; wherein: the third branch pipe is sequentially provided with a fifth control valve, a liquid storage tank, a drying filter and an expansion valve group, and the expansion valve group at least includes a first expansion valve and a second expansion valve arranged in parallel; the fourth branch pipe is provided with a sixth control valve; the fifth branch pipe is sequentially provided with a mass flowmeter and a seventh control valve located downstream of the variable frequency pump; the sixth branch pipe is provided with an eighth control valve, a fourth temperature sensor and a fourth pressure transmitter.

[0016] In some specific embodiments, the third branch pipe is connected to the sixth branch pipe through a first bypass pipe, and the connection point between the first bypass pipe and the third branch pipe is located upstream of the fifth control valve; the connection point between the first bypass pipe and the fourth branch pipe is located between the sixth control valve and the fourth temperature sensor; the first bypass pipe is provided with a first bypass valve, a fifth temperature sensor and a fifth pressure transmitter in sequence; the third branch pipe is connected to the fifth branch pipe through a second bypass pipe, and the connection point between the second bypass pipe and the third branch pipe is located between the fifth control valve and the liquid storage tank, and the connection point between the second bypass pipe and the fifth branch pipe is located downstream of the seventh control valve, and the second bypass pipe is provided with a second bypass valve; the fifth branch pipe is connected to the sixth branch pipe through a third bypass pipe, and the connection point between the third bypass pipe and the fifth branch pipe is located between the mass flowmeter and the seventh control valve, and the connection point between the third bypass pipe and the sixth branch pipe is located between the eighth control valve and the fourth temperature sensor, and the third bypass pipe is provided with a third bypass valve.

[0017] In some embodiments, the third heat exchange tube is connected to the air return port of the variable frequency compressor through an air intake pipe, and a gas-liquid separation element is provided on the air intake pipe.

[0018] The beneficial effects of the battery pack thermal management test system of the present invention are as follows: during the test process, when a battery pack completes the test, it switches to the refrigerant recovery mode. In this mode, the variable frequency pump stops working, and the refrigerant remaining in the battery pack passes through the second test pipeline and the third heat exchange tube and returns to the variable frequency compressor, avoiding the residual refrigerant in the battery pack and ensuring the normal test of the next test. And when the battery pack needs to be replaced for testing, it is only necessary to close the first control valve and the second control valve to disconnect the battery pack from the battery pack thermal management test system, and replace a different battery pack, so that the battery pack thermal management test system can be compatible with various types of battery pack tests and meet the test requirements of various types of battery packs.

[0019] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of a battery pack thermal management test system according to an embodiment of the present invention.

[0021] Figure 2 It is a schematic diagram of refrigerant flow in the direct cooling test mode of the battery pack thermal management test system according to an embodiment of the present invention.

[0022] Figure 3 It is a schematic diagram of refrigerant flow in the direct heating test mode of the battery pack thermal management test system according to an embodiment of the present invention.

[0023] Figure 4 It is a schematic diagram of refrigerant circulation in the refrigerant recovery mode of the battery pack thermal management test system according to an embodiment of the present invention.

[0024] Reference numerals:

[0025] 1. Variable frequency compressor; 2. First temperature sensor; 3. First pressure transmitter; 4. Oil separator; 5. Third control valve; 6. Fourth control valve; 7. Condenser; 8. Variable frequency fan; 9. Third sight glass; 10. Third temperature sensor; 11. Third pressure transmitter; 12. Expansion tank; 13. First non-return valve; 14. First electric heating pipe; 15. First exhaust pipeline; 16. First circulation pump; 17. Oil return capillary; 18. First heat exchange unit; 19. Fifth control valve; 20. First bypass valve; 21. Liquid storage tank; 22. Dry filter; 23. First expansion valve; 24. Second expansion valve; 25. Gas-liquid separator; 26. Third branch pipe; 27. Fourth branch pipe; 28. Fifth branch pipe; 29. ​​Sixth branch pipe; 30. Suction pipe; 31. Variable frequency pump; 32. Mass flow meter; 33. First A sight glass; 34, a first control valve; 35, a second control valve; 36, a battery pack; 37, a seventh control valve; 38, a second bypass valve; 39, a third bypass valve; 40, a sixth control valve; 41, a first test pipeline; 42, a second test pipeline; 43, a second sight glass; 44, a fifth temperature sensor; 45, a fifth pressure transmitter; 46, an eighth control valve; 47, a fourth temperature sensor; 48, a fourth pressure transmitter; 49, a liquid adding pipeline; 50, a second one-way valve; 51, a second electric heating pipe; 52, a second exhaust pipeline; 53, a second circulation pump; 54, a second heat exchange unit; 55, a gas-liquid separator; 56, a second temperature sensor; 57, a second pressure transmitter; 58, a first branch pipe; 59, a second branch pipe; 60, a first bypass pipe; 61, a second bypass pipe; 62, a third bypass pipe. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0027] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0029] In the description of this embodiment, the terms "upper", "lower", "right", etc., directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0030] The present invention discloses a battery pack thermal management test system, referring to Figure 1As shown, it includes a variable frequency compressor 1, a condenser 7, a first heat exchange unit 18, a second heat exchange unit 54, a gas-liquid separator 25, a variable frequency pump 31, a first test pipeline 41 and a second test pipeline 42. A variable frequency fan 8 is correspondingly arranged on the condenser 7. The first heat exchange unit 18 has a first heat exchange tube and a second heat exchange tube. The second heat exchange unit 54 has a third heat exchange tube and a fourth heat exchange tube. The first heat exchange tube and the third heat exchange tube are used to circulate refrigerant, and the second heat exchange tube and the fourth heat exchange tube are used to circulate heat exchange medium. A first control valve 34 is arranged on the first test pipeline 41, a second control valve 35 is arranged on the second test pipeline 42, and a battery pack 36 is replaceably installed between the first test pipeline 41 and the second test pipeline 42. The battery pack thermal management test system has a direct cooling test mode, a direct heating test mode and a refrigerant recovery mode.

[0031] It should be noted that in the actual working process, in the direct cooling test mode ( Figure 2 In the mode shown), the refrigerant flows out of the variable frequency compressor 1, passes through the condenser 7 and the first heat exchange tube in turn to reach the gas-liquid separator 25. Driven by the variable frequency pump 31, the liquid refrigerant enters the third heat exchange tube from the liquid outlet of the gas-liquid separator 25 through the first test pipeline 41, the battery pack 36 and the second test pipeline 42. The gaseous refrigerant enters the third heat exchange tube from the gas outlet of the gas-liquid separator 25. The two refrigerants merge in the third heat exchange tube and return to the variable frequency compressor 1. In the direct heat test mode ( Figure 3 In the refrigerant recovery mode ( Figure 4 In the mode shown in the figure, the variable frequency pump 31 stops working, and the refrigerant remaining in the battery pack 36 returns to the variable frequency compressor 1 after passing through the second test pipeline 42 and the third heat exchange pipe.

[0032] It is understandable that during the test, when a battery pack 36 completes the test, it switches to the refrigerant recovery mode. In this mode, the variable frequency pump 31 stops working, and the refrigerant remaining in the battery pack 36 passes through the second test pipeline 42 and the third heat exchange tube and returns to the variable frequency compressor 1, avoiding the residual refrigerant in the battery pack 36 and ensuring the normal test of the next time. And when it is necessary to replace the battery pack 36 for testing, it is only necessary to close the first control valve 34 and the second control valve 35, disconnect the battery pack 36 from the battery pack thermal management test system, and replace a different battery pack 36, so that the battery pack thermal management test system can be compatible with various types of battery pack 36 tests and meet the test requirements of various types of battery packs 36.

[0033] refer to Figure 1 As shown, the battery pack thermal management test system also includes a first temperature sensor 2, a first pressure transmitter 3, a second temperature sensor 56 and a second pressure transmitter 57. The first temperature sensor 2 and the first pressure transmitter 3 are connected to the air outlet of the variable frequency compressor 1 in sequence, and the second pressure transmitter 57 and the second temperature sensor 56 are connected to the air return port of the variable frequency compressor 1 in sequence. It can be understood that the first temperature sensor 2 monitors the exhaust temperature of the variable frequency compressor 1, and the first pressure transmitter 3 monitors the exhaust pressure of the variable frequency compressor 1. If the exhaust temperature and the exhaust pressure exceed the system setting value, an alarm is issued to shut down the machine, thereby protecting the variable frequency compressor 1. The second temperature sensor 56 can detect the suction temperature of the variable frequency compressor 1. If the suction temperature is too low, the second heat exchange unit 54 is started, and the fourth heat exchange tube of the second heat exchange unit 54 exchanges heat with the refrigerant in the third heat exchange tube, so that the suction temperature detected by the second temperature sensor 56 increases, thereby avoiding the phenomenon of liquid hammer in the variable frequency compressor 1. The suction pressure is detected by the second pressure transmitter 57, and an alarm signal is issued when the suction pressure is too low, so as to prevent the system from being in a negative pressure operation state for a long time.

[0034] refer to Figure 1 As shown, the battery pack thermal management test system also includes a first sight glass 33 and a second sight glass 43. The first sight glass 33 is arranged on the first test pipeline 41 and is located upstream of the first control valve 34. The second sight glass 43 is arranged on the second test pipeline 42 and is located downstream of the second control valve 35. It can be understood that in the direct cooling test mode, the experimenter can observe the dryness of the refrigerant at the cold plate inlet of the battery pack 36 through the first sight glass 33. In the direct heating test mode, the experimenter can also observe the refrigerant state at the cold plate outlet of the battery pack 36 through the first sight glass 33 and observe the refrigerant state at the cold plate inlet of the battery pack 36 through the second sight glass 43, so as to facilitate the experimenter to adjust the operating state of the battery pack thermal management test system according to the state of the refrigerant and realize intelligent testing.

[0035] refer to Figure 1As shown, the battery pack thermal management test system also includes a third sight glass 9, a third temperature sensor 10 and a third pressure transmitter 11. At the entrance of the first heat exchange tube, the third sight glass 9, the third temperature sensor 10 and the third pressure transmitter 11 are arranged in sequence along the refrigerant flow direction. It can be understood that the experimenter can observe the refrigerant state through the third sight glass 9, the third temperature sensor 10 detects the refrigerant temperature, and the third pressure transmitter 11 detects the refrigerant pressure. The third temperature sensor 10 and the third pressure transmitter 11 play a feedback control role in the direct cooling test mode, that is, the speed of the variable frequency fan 8 can be adjusted according to the detection results of the third temperature sensor 10 and the third pressure transmitter 11, thereby adjusting the condensing pressure and the degree of supercooling; while in the direct heating test mode, the third temperature sensor 10 and the third pressure transmitter 11 only play a detection role. As a result, it is convenient for the experimenter to adjust the operating state of the battery pack thermal management test system according to the state of the refrigerant and realize intelligent testing.

[0036] refer to Figure 1 As shown, the battery pack thermal management test system also includes an oil separator 4, the inlet of the oil separator 4 is connected to the air outlet of the variable frequency compressor 1, the oil return port of the oil separator 4 is connected to the oil recovery port of the variable frequency compressor 1 through the oil return capillary 17, and the outlet of the oil separator 4 is provided with a first branch pipe 58 and a second branch pipe 59, the first branch pipe 58 is connected to the first heat exchange tube, the second branch pipe 59 is arranged in parallel with the first branch pipe 58, and the condenser 7 is installed on the second branch pipe 59; the first branch pipe 58 is provided with a third control valve 5, and the second branch pipe 59 is provided with a fourth control valve 6; the outlet of the oil separator 4 is directly connected to the condenser 7 and one of the first heat exchange tubes through the third control valve 5 and the fourth control valve 6 in a switchable manner.

[0037] It is understandable that in the actual working process, the refrigerant passes through the oil separator 4, and the separated lubricating oil returns to the variable frequency compressor 1 through the oil return capillary 17, ensuring that there is enough lubricating oil in the variable frequency compressor 1, thereby ensuring that the variable frequency compressor 1 can work normally. At the same time, the third control valve 5 and the fourth control valve 6 can determine whether the refrigerant enters the first heat exchange tube directly after leaving, or enters the condenser 7 first and then enters the first heat exchange tube. Specifically, in the direct cooling test mode, the refrigerant first enters the condenser 7 and then enters the first heat exchange tube; in the direct heating test mode, the refrigerant directly enters the first heat exchange tube, and in this mode, the fourth control valve 6 can be selectively opened according to the cold plate inlet pressure of the battery pack 36 to avoid the phenomenon of excessive cold plate inlet pressure. The third control valve 5 and the fourth control valve 6 facilitate intelligent testing.

[0038] refer to Figure 1As shown, the battery pack thermal management test system also includes a first electric heating tube 14, a first circulation pump 16, a second electric heating tube 51, and a second circulation pump 53. The first electric heating tube 14 and the second electric heating tube 51 are used to circulate heat exchange medium. The first circulation pump 16 is used to drive the heat exchange medium to circulate in the first electric heating tube 14 and the second heat exchange tube; the second circulation pump 53 is used to drive the heat exchange medium to circulate in the second electric heating tube 51 and the fourth heat exchange tube. It can be understood that in the actual working process, in the direct cooling test mode and the direct heating test mode, if the suction temperature is too low, the second electric heating pipe 51 is started, and the second circulating pump 53 drives the heat exchange medium to exchange heat with the refrigerant in the third heat exchange pipe through the fourth heat exchange pipe of the second heat exchange unit 54, so that a small amount of liquid refrigerant flowing in the third heat exchange pipe absorbs heat and evaporates, so that the suction temperature of the variable frequency compressor 1 is increased, and the phenomenon of liquid hammer in the variable frequency compressor 1 is avoided; and in the direct heating test mode, the second heat exchange unit 54 acts as an evaporator, and when the liquid refrigerant flows through the third heat exchange pipe, the second electric heating pipe 51 is started, and the second circulating pump 53 drives the heat exchange medium (ethylene glycol aqueous solution) to exchange heat with the refrigerant in the third heat exchange pipe through the fourth heat exchange pipe of the second heat exchange unit 54. The first electric heating pipe 14 and the second electric heating pipe 51 are used to heat the heat exchange medium, and the temperature control accuracy is more accurate and the control response is faster.

[0039] Optionally, the battery pack thermal management test system also includes an expansion tank 12, to which is connected a first liquid replenishment pipeline, a first exhaust pipeline 15, a second liquid replenishment pipeline, a second exhaust pipeline 52 and a liquid adding pipeline 49; wherein: the first liquid replenishment pipeline is connected to the first electric heating tube 14, and a first one-way valve 13 is provided on the first liquid replenishment pipeline; the second liquid replenishment pipeline is connected to the second electric heating tube 51, and a second one-way valve 50 is provided on the second liquid replenishment pipeline; the first exhaust pipeline 15 and the second exhaust pipeline 52 are respectively connected to the exhaust ports of the first electric heating tube 14 and the second electric heating tube 51. It can be understood that the expansion tank 12 is used to store the fluid exchange medium. The first fluid replenishment pipeline and the second fluid replenishment pipeline can conveniently replenish the heat exchange medium into the first electric heating tube 14 and the second electric heating tube 51. The first one-way valve 13 and the second one-way valve 50 can prevent the heat exchange medium from flowing back, thereby preventing the heat exchange medium in the first electric heating tube 14 and the second electric heating tube 51 from entering the expansion tank 12. The first exhaust pipeline 15 and the second exhaust pipeline 52 can discharge the first electric heating tube 14 and the second electric heating tube 51 to improve the heating efficiency of the first electric heating tube 14 and the second electric heating tube 51.

[0040] Of course, it should be additionally explained here that in other embodiments of the present invention, the specific composition of the first heat exchange unit 18 and the second heat exchange unit 54 can also select other structures according to actual needs, such as a heat pump heating system.

[0041] refer to Figure 1As shown, the refrigerant inlet of the gas-liquid separator 25 is connected to the outlet of the second heat exchange tube through the third branch pipe 26, the gas outlet of the gas-liquid separator 25 is connected to the second test pipeline 42 through the fourth branch pipe 27, the liquid outlet of the gas-liquid separator 25 is connected to the first test pipeline 41 through the fifth branch pipe 28, and the second test pipeline 42 is connected to the inlet of the third heat exchange tube through the sixth branch pipe 29: the third branch pipe 26 is provided with a fifth control valve 19, a liquid storage tank 21, a drying filter 22 and an expansion valve group in sequence, and the expansion valve group at least includes a first expansion valve 23 and a second expansion valve 24 arranged in parallel; the fourth branch pipe 27 is provided with a sixth control valve 40; the fifth branch pipe 28 is provided with a mass flow meter 32 and a seventh control valve 37 located downstream of the variable frequency pump 31 in sequence; the sixth branch pipe 29 is provided with an eighth control valve 46, a fourth temperature sensor 47 and a fourth pressure transmitter 48.

[0042] It is understandable that the liquid storage tank 21 and the drying filter 22 can dry the refrigerant, remove the moisture in the refrigerant, ensure the cooling capacity of the refrigerant, and throttle the first expansion valve 23 and the second expansion valve 24 in parallel, on the one hand, expand the cooling capacity adjustment range of the equipment, and on the other hand, reduce the number of electronic expansion valve action steps, so that the response is faster and the adjustment is more precise. By setting the third branch pipe 26, the fourth branch pipe 27, the fifth branch pipe 28, the sixth branch pipe 29, the fifth control valve 19, the sixth control valve 40, the seventh control valve 37 and the eighth control valve 46, intelligent testing can be achieved to facilitate the battery pack thermal management test system to switch between the direct cooling test mode, the direct heating test mode and the refrigerant recovery mode. Specifically, in the direct cooling test mode, the fifth control valve 19 is turned on, the sixth control valve 40 is turned on, the seventh control valve 37 is turned on, and the eighth control valve 46 is turned on; in the direct heating test mode, the fifth control valve 19 is closed, the sixth control valve 40 is closed, the seventh control valve 37 is closed, and the eighth control valve 46 is closed; in the refrigerant recovery mode, the fifth control valve 19 is turned on, the sixth control valve 40 is closed, the seventh control valve 37 is closed, and the eighth control valve 46 is turned on.

[0043] In addition, the fourth temperature sensor 47 and the fourth pressure transmitter 48 can detect the cold plate outlet pressure and overheat of the battery pack 36. The variable frequency pump 31 can adjust the motor speed and control the supply amount of liquid refrigerant by controlling the frequency. The mass flow meter 32 can detect the refrigerant flow output by the variable frequency pump 31. Battery R&D engineers can formulate the control logic of the battery pack 36 during actual operation based on the refrigerant flow test data.

[0044] Optionally, the third branch pipe 26 and the sixth branch pipe 29 are connected through the first bypass pipe 60, and the connection point between the first bypass pipe 60 and the third branch pipe 26 is located upstream of the fifth control valve 19; the connection point between the first bypass pipe 60 and the fourth branch pipe 27 is located between the sixth control valve 40 and the fourth temperature sensor 47; the first bypass pipe 60 is provided with the first bypass valve 20, the fifth temperature sensor 44 and the fifth pressure transmitter 45 in sequence; the third branch pipe 26 and the fifth branch pipe 28 are connected through the second bypass pipe 61, and the connection point between the second bypass pipe 61 and the third branch pipe 26 is located Between the fifth control valve 19 and the liquid storage tank 21, the connecting point of the second bypass pipe 61 and the fifth branch pipe 28 is located downstream of the seventh control valve 37, and the second bypass pipe 61 is provided with a second bypass valve 38; the fifth branch pipe 28 and the sixth branch pipe 29 are connected through the third bypass pipe 62, and the connecting point of the third bypass pipe 62 and the fifth branch pipe 28 is located between the mass flowmeter 32 and the seventh control valve 37, and the connecting point of the third bypass pipe 62 and the sixth branch pipe 29 is located between the eighth control valve 46 and the fourth temperature sensor 47, and the third bypass pipe 62 is provided with a third bypass valve 39.

[0045] It is understandable that by setting the first bypass pipe 60, the second bypass pipe 61, the third bypass pipe 62, the first bypass valve 20, the second bypass valve 38 and the third bypass valve 39, intelligent testing can be achieved to facilitate the battery pack thermal management test system to switch between the direct cooling test mode, the direct heating test mode and the refrigerant recovery mode. Specifically, in the direct cooling test mode, the first bypass valve 20 is closed, the second bypass valve 38 is closed, and the third bypass valve 39 is closed; in the direct heating test mode, the first bypass valve 20 is turned on, the second bypass valve 38 is turned on, and the third bypass valve 39 is turned on; in the refrigerant recovery mode, the first bypass valve 20 is closed and the second bypass valve 38 is closed.

[0046] refer to Figure 1 As shown, the third heat exchange pipe is connected to the return air port of the variable frequency compressor 1 through the suction pipe 30, and a gas-liquid separator 55 is provided on the suction pipe 30. It can be understood that in the direct heating test mode, the direct cooling test mode and the refrigerant recovery mode, the liquid refrigerant can be stored in the additional gas-liquid separator 55, and the gaseous refrigerant returns to the variable frequency compressor 1 through the suction pipe 30 to complete the direct cooling test circuit, the direct heating test circuit or the refrigerant recovery, thereby preventing the liquid refrigerant from entering the variable frequency compressor 1 to cause liquid hammer.

[0047] The following is a detailed description of three operating conditions of the battery pack thermal management test system according to an embodiment of the present invention.

[0048] Direct cooling test mode:

[0049] Close the first control valve 34 and the second control valve 35, and replace a different battery pack 36; after the battery pack 36 is replaced, the battery pack 36, the first test pipeline 41, and the second test pipeline 42 are evacuated through the needle valve provided on the first test pipeline 41 to complete the test preparation.

[0050] The first control valve 34 and the second control valve 35 are opened to connect the battery pack thermal management test system and the battery pack 36 ; the battery pack thermal management test system communicates with the control system of the battery pack 36 and receives instructions from the control system.

[0051] The control system monitors the cell temperature of the battery pack 36. When the cell temperature exceeds a set value, the control system sends a start-up refrigeration instruction to the battery pack thermal management test system, and the variable frequency compressor 1 starts to run.

[0052] The refrigerant passes through the oil separator 4 , and the separated lubricating oil returns to the variable frequency compressor 1 through the oil return capillary 17 .

[0053] The third control valve 5 is powered off and closed, the fourth control valve 6 is powered on, the fifth control valve 19 is powered on, the sixth control valve 40 is powered on, the seventh control valve 37 is powered on, the eighth control valve 46 is powered on, the first bypass valve 20 is powered off and closed, the second bypass valve 38 is powered off and closed, and the third bypass valve 39 is powered off and closed.

[0054] The refrigerant output by the variable frequency compressor 1 enters the condenser 7 through the second branch pipe 59 for condensation, and flows out of the condenser 7 and into the first heat exchange tube of the first heat exchange unit 18; the refrigerant flows out of the first heat exchange tube and flows into the third branch pipe 26, and then into the liquid storage tank 21 and the drying filter 22, and is throttled at the first expansion valve 23 and the second expansion valve 24. The refrigerant in the gas-liquid mixed state after throttling flows into the gas-liquid separator 25.

[0055] The gaseous refrigerant in the gas-liquid separator 25 flows into the sixth branch pipe 29 through the fourth branch pipe 27. The liquid refrigerant in the gas-liquid separator 25 enters the fifth branch pipe 28 under the extraction of the variable frequency pump 31, passes through the mass flow meter 32, and enters the battery pack 36 through the first test pipeline 41 to cool the battery pack 36. After cooling, the gaseous refrigerant enters the sixth branch pipe 29 through the second test pipeline 42. The refrigerant entering the sixth branch pipe 29 (most of it is gaseous and a small part is liquid) passes through the third heat exchange pipe of the second heat exchange unit 54 and enters the gas-liquid separator 55. The liquid refrigerant is stored in the gas-liquid separator 55. The gaseous refrigerant returns to the variable frequency compressor 1 through the suction pipe 30 to complete the direct cooling test circuit.

[0056] It should be noted that during the test, the first temperature sensor 2 monitors the exhaust temperature of the variable frequency compressor 1, and the first pressure transmitter 3 monitors the exhaust pressure of the variable frequency compressor 1. If the exhaust temperature and the exhaust pressure exceed the system setting value, an alarm is issued to shut down the machine, thereby protecting the variable frequency compressor 1. The experimenter can observe the refrigerant state through the third sight glass 9, the condensing pressure is detected by the third pressure transmitter 11, the supercooling is detected by the third temperature sensor 10, the detection result of the condenser 7 matches the variable frequency fan 8, and the condensing pressure and the supercooling are adjusted by controlling the speed of the variable frequency fan 8. The fourth temperature sensor 47 and the fourth pressure transmitter 48 can detect the outlet pressure and superheat of the cold plate of the battery pack 36, and feed back to the control system. The variable frequency pump 31 can adjust the motor speed by controlling the frequency, and control the liquid supply of the liquid refrigerant. The mass flowmeter 32 can detect the refrigerant flow output by the variable frequency pump 31, and the experimenter can observe the refrigerant dryness at the cold plate inlet of the battery pack 36 through the first sight glass 33.

[0057] It should be noted that during the test, the second temperature sensor 56 can detect the suction temperature of the variable frequency compressor 1. If the suction temperature is too low, the second electric heating tube 51 is started, and the second circulation pump 53 drives the heat exchange medium (ethylene glycol aqueous solution) to exchange heat with the refrigerant in the third heat exchange tube through the fourth heat exchange tube of the second heat exchange unit 54, so that a small amount of liquid refrigerant flowing in the third heat exchange tube absorbs heat and evaporates, so that the suction temperature detected by the second temperature sensor 56 increases, thereby avoiding liquid hammer in the variable frequency compressor 1; that is, the suction temperature detected by the second temperature sensor 56 is fed back to the control system to control the output ratio of the second electric heating tube 51 to achieve suction temperature regulation; the suction pressure is detected by the second pressure transmitter 57, and an alarm signal is issued when the suction pressure is too low to avoid the system being in a negative pressure operation state for a long time.

[0058] Direct heat test mode:

[0059] The control system monitors the cell temperature of the battery pack 36. When the cell temperature exceeds a set value, the control system sends a start-up refrigeration instruction to the battery pack thermal management test system, and the variable frequency compressor 1 starts to run.

[0060] The refrigerant passes through the oil separator 4 , and the separated lubricating oil returns to the variable frequency compressor 1 through the oil return capillary 17 .

[0061] The third control valve 5 is electrically turned on, the fourth control valve 6 is electrically turned off and closed, the fifth control valve 19 is electrically turned off and closed, the sixth control valve 40 is electrically turned off and closed, the seventh control valve 37 is electrically turned off and closed, the eighth control valve 46 is electrically turned off and closed, the first bypass valve 20 is electrically turned on, the second bypass valve 38 is electrically turned on, and the third bypass valve 39 is electrically turned on, and through the above valve actions, the test mode is switched from the direct cooling test mode to the direct heating test mode.

[0062] The refrigerant output by the variable frequency compressor 1 enters the heat exchange tube of the first heat exchange unit 18 through the first branch pipe 58, and then enters the second test pipeline 42 through the third branch pipe 26 and the first bypass pipe 60 in sequence, and enters the battery pack 36 from the second test pipeline 42 to be heated. After the heating is completed, the refrigerant enters the first test pipeline 41, and then passes through the second bypass pipe 61, the liquid storage tank 21 and the drying filter 22 in sequence, and is throttled at the first expansion valve 23 and the second expansion valve 24. The refrigerant in the gas-liquid mixed state after throttling flows into the gas-liquid separator 25; the liquid refrigerant in the gas-liquid separator 25 enters the fifth branch pipe 28 under the extraction of the variable frequency pump 31, and passes through the mass The refrigerant flows through the third bypass pipe 62 into the sixth branch pipe 29 after measuring the flow meter 32; the second heat exchange unit 54 acts as an evaporator. When the liquid refrigerant flows through the third heat exchange tube, the second electric heating tube 51 is started, and the second circulation pump 53 drives the heat exchange medium (ethylene glycol aqueous solution) to pass through the fourth heat exchange tube of the second heat exchange unit 54 to exchange heat with the refrigerant in the third heat exchange tube, so that the liquid refrigerant flowing in the third heat exchange tube absorbs heat and evaporates. Then, when the refrigerant (most of it is gaseous and a small part is liquid) passes through the gas-liquid separator 55, the liquid refrigerant is stored in the gas-liquid separator 55, and the gaseous refrigerant returns to the variable frequency compressor 1 through the suction pipe 30 to complete the direct heating test circuit.

[0063] It should be noted that during the test, the experimenter can observe the refrigerant state through the third sight glass 9, the third temperature sensor 10 detects the refrigerant temperature, and the third pressure transmitter 11 detects the refrigerant pressure. The third temperature sensor 10 and the third pressure transmitter 11 play a feedback control role in the direct cooling test mode, and only play a detection role in the direct heating test mode; the experimenter can also observe the refrigerant state at the cold plate outlet of the battery pack 36 through the first sight glass 33, and observe the refrigerant state at the cold plate inlet of the battery pack 36 through the second sight glass 43; the fourth temperature sensor 47 detects the liquid refrigerant temperature, thereby controlling the speed of the variable frequency pump 31 and controlling the flow rate, and the fourth pressure transmitter 48 detects the liquid refrigerant pressure and controls the opening of the first expansion valve 23 and the second expansion valve 24.

[0064] It should be noted that, during the test, the fifth temperature sensor 44 detects the cold plate inlet temperature of the battery pack 36. When the cold plate inlet temperature is lower than the set value, the first electric heating tube 14 of the first heat exchange unit 18 is started, and the first circulation pump 16 drives the heat exchange medium (ethylene glycol aqueous solution) to exchange heat with the refrigerant in the first heat exchange tube through the second heat exchange tube of the first heat exchange unit 18 to heat the refrigerant, thereby ensuring the refrigerant temperature and temperature control accuracy entering the battery pack 36; the fifth pressure transmitter 45 detects the cold plate inlet pressure of the battery pack 36. If the cold plate inlet pressure is higher than the set value, the fourth control valve 6 is energized and the variable frequency fan 8 is started. If the cold plate inlet pressure is lower than the set value, the fourth control valve 6 is de-energized and closed, and the variable frequency fan 8 is closed; the second temperature sensor The sensor 56 detects the suction temperature of the variable frequency compressor 1. If the suction temperature is too low, the second electric heating pipe 51 is started, and the second circulating pump 53 drives the heat exchange medium (ethylene glycol aqueous solution) to exchange heat with the refrigerant in the third heat exchange pipe through the fourth heat exchange pipe of the second heat exchange unit 54, so that a small amount of liquid refrigerant flowing in the third heat exchange pipe absorbs heat and evaporates, so that the suction temperature detected by the second temperature sensor 56 increases, and the phenomenon of liquid hammer in the variable frequency compressor 1 is avoided; that is, the suction temperature detected by the second temperature sensor 56 is fed back to the control system, and the output ratio of the second electric heating pipe 51 is controlled to realize the suction temperature regulation; the suction pressure is detected by the second pressure transmitter 57, and an alarm signal is issued when the suction pressure is too low, so as to avoid the system being in a negative pressure operation state for a long time.

[0065] Refrigerant recovery mode:

[0066] After the direct cooling test and the direct heating test are completed, the next battery pack 36 needs to be replaced. At this time, the refrigerant in the cold plate of the tested battery pack 36 needs to be recovered to the test system.

[0067] The variable frequency compressor 1 keeps working, the third control valve 5 loses power and closes, the fourth control valve 6 is energized and turned on, the fifth control valve 19 is energized and turned on, the sixth control valve 40 loses power and closes, the seventh control valve 37 loses power and closes, the eighth control valve 46 is energized and turned on, the first bypass valve 20 loses power and closes, the second bypass valve 38 loses power and closes, the variable frequency pump 31 is closed, the variable frequency fan 8 works at a fixed frequency, the first expansion valve 23 and the second expansion valve 24 work at a fixed opening, and the refrigerant remaining in the cold plate of the battery pack 36 is returned to the variable frequency compressor 1 through the second test pipeline 42, the sixth branch pipe 29, the third heat exchange pipe and the suction pipe 30 in sequence under the action of the variable frequency compressor 1.

[0068] It should be noted that when the fourth pressure transmitter 48 detects that the pressure is lower than 0Kpa, the eighth control valve 46 loses power and closes, disconnecting the test system and the battery pack 36, closing the first control valve 34 and the second control valve 35, and replacing the next battery pack 36.

[0069] The advantages of the battery pack thermal management test system of the present invention are as follows:

[0070] First, through the internal valve group control, the three working modes of direct cooling test mode, direct heating test mode and refrigerant recovery mode can be switched, integrating multiple functions in one. Customers do not need to purchase multiple devices to meet testing needs, saving laboratory space and R&D costs;

[0071] Second, by using the variable frequency compressor 1, the variable frequency fan 8 and the variable frequency pump 31, the whole machine working condition can be adjusted accurately and quickly according to the load of the tested battery pack 36, so that the whole machine operation boundary and operation range are wide, meeting the testing requirements of battery packs 36 of different capacities, and the equipment is more versatile;

[0072] Third, the variable frequency fan 8 is used to control the condensing pressure more accurately and respond more quickly;

[0073] Fourth, the electric heating tube is used to heat the heat exchange medium, the temperature control accuracy is more accurate, and the control response is faster;

[0074] Fifth, the expansion valve group adopts the method of installing multiple expansion valves in parallel, with small adjustment steps, more precise control and faster response;

[0075] Sixth, the frequency conversion pump 31 is used to cool the battery pack 36. The pure liquid refrigerant has a better cooling effect than the gas-liquid two-phase refrigerant, and can quickly suppress the temperature of the rapidly heated battery pack 36, and the temperature is more uniform;

[0076] Seventh: The refrigerant recovery mode only requires one-button operation to complete the refrigerant recovery, which is convenient and fast.

[0077] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0078] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A battery pack thermal management test system, characterized in that: The invention comprises a variable frequency compressor (1), a condenser (7), a first heat exchange unit (18), a second heat exchange unit (54), a gas-liquid separator (25), a variable frequency pump (31), a first test pipeline (41) and a second test pipeline (42); a variable frequency fan (8) is correspondingly arranged on the condenser (7); the first heat exchange unit (18) has a first heat exchange tube and a second heat exchange tube; the second heat exchange unit (54) has a third heat exchange tube and a fourth heat exchange tube; the first heat exchange tube and the third heat exchange tube are used for circulating refrigerant; the second heat exchange tube and the fourth heat exchange tube are used for circulating heat exchange medium; a first control valve (34) is arranged on the first test pipeline (41); a second control valve (35) is arranged on the second test pipeline (42); and a battery pack (36) is replaceably installed between the first test pipeline (41) and the second test pipeline (42); The battery pack thermal management test system has a direct cooling test mode, a direct heating test mode and a refrigerant recovery mode; wherein: In the direct cooling test mode, the refrigerant flows out of the variable frequency compressor (1) and passes through the condenser (7) and the first heat exchange tube in sequence to reach the gas-liquid separator (25). Driven by the variable frequency pump (31), the liquid refrigerant flows from the liquid outlet of the gas-liquid separator (25) through the first test pipeline (41), the battery pack (36) and the second test pipeline (42) and then enters the third heat exchange tube. The gaseous refrigerant enters the third heat exchange tube from the gas outlet of the gas-liquid separator (25). The two refrigerants merge in the third heat exchange tube and return to the variable frequency compressor (1). In the direct heating test mode, the refrigerant flows out of the variable frequency compressor (1), passes through the first heat exchange tube, the second test pipeline (42), the battery pack (36) and the first test pipeline (41), and then enters the gas-liquid separator (25). All the refrigerant enters the third heat exchange tube from the liquid outlet of the gas-liquid separator (25) driven by the variable frequency pump (31), and the refrigerant returns to the variable frequency compressor (1) after exchanging heat with the heat exchange medium. In the refrigerant recovery mode, the variable frequency pump (31) stops working, and the refrigerant remaining in the battery pack (36) returns to the variable frequency compressor (1) after passing through the second test pipeline (42) and the third heat exchange pipe; When the battery pack (36) needs to be replaced for testing, the first control valve (34) and the second control valve (35) are closed to disconnect the battery pack from the battery pack thermal management test system, and a different battery pack (36) is replaced.

2. The battery pack thermal management test system according to claim 1, characterized in that: The battery pack thermal management test system further comprises a first temperature sensor (2), a first pressure transmitter (3), a second temperature sensor (56) and a second pressure transmitter (57); the first temperature sensor (2) and the first pressure transmitter (3) are connected to the air outlet of the variable frequency compressor (1) in sequence; the second pressure transmitter (57) and the second temperature sensor (56) are connected to the air return port of the variable frequency compressor (1) in sequence.

3. The battery pack thermal management test system according to claim 1, characterized in that: The battery pack thermal management test system further comprises a first sight glass (33) and a second sight glass (43), wherein the first sight glass (33) is arranged on the first test pipeline (41) and is located upstream of the first control valve (34), and the second sight glass (43) is arranged on the second test pipeline (42) and is located downstream of the second control valve (35).

4. The battery pack thermal management test system according to claim 1, characterized in that: The battery pack thermal management test system also includes a third sight glass (9), a third temperature sensor (10) and a third pressure transmitter (11). At the inlet of the first heat exchange tube, the third sight glass (9), the third temperature sensor (10) and the third pressure transmitter (11) are arranged in sequence along the refrigerant flow direction.

5. The battery pack thermal management test system according to claim 1, characterized in that: The battery pack thermal management test system also includes an oil separator (4), the inlet of the oil separator (4) is connected to the air outlet of the variable frequency compressor (1), the oil return port of the oil separator (4) is connected to the oil recovery port of the variable frequency compressor (1) through an oil return capillary (17), the outlet of the oil separator (4) is provided with a first branch pipe (58) and a second branch pipe (59), the first branch pipe (58) is connected to the first heat exchange tube, the second branch pipe (59) is arranged in parallel with the first branch pipe (58), and the condenser (7) is installed on the second branch pipe (59); the first branch pipe (58) is provided with a third control valve (5), and the second branch pipe (59) is provided with a fourth control valve (6); the outlet of the oil separator (4) is directly connected to the condenser (7) and one of the first heat exchange tubes through the third control valve (5) and the fourth control valve (6) in a switchable manner.

6. The battery pack thermal management test system according to claim 1, characterized in that: The battery pack thermal management test system also includes a first electric heating tube (14), a first circulation pump (16), a second electric heating tube (51), and a second circulation pump (53). The first electric heating tube (14) and the second electric heating tube (51) are used to circulate a heat exchange medium. The first circulation pump (16) is used to drive the heat exchange medium to circulate in the first electric heating tube (14) and the second heat exchange tube; the second circulation pump (53) is used to drive the heat exchange medium to circulate in the second electric heating tube (51) and the fourth heat exchange tube.

7. The battery pack thermal management test system according to claim 6, characterized in that: The battery pack thermal management test system further comprises an expansion tank (12), to which a first liquid replenishing pipeline, a first exhaust pipeline (15), a second liquid replenishing pipeline, a second exhaust pipeline (52) and a liquid adding pipeline (49) are connected; wherein: The first liquid replenishment pipeline is connected to the first electric heating pipe (14), and a first one-way valve (13) is provided on the first liquid replenishment pipeline; the second liquid replenishment pipeline is connected to the second electric heating pipe (51), and a second one-way valve (50) is provided on the second liquid replenishment pipeline; the first exhaust pipeline (15) and the second exhaust pipeline (52) are respectively connected to the exhaust ports of the first electric heating pipe (14) and the second electric heating pipe (51).

8. The battery pack thermal management test system according to claim 1, characterized in that: The refrigerant inlet of the gas-liquid separator (25) is connected to the outlet of the second heat exchange tube through the third branch pipe (26), the gas outlet of the gas-liquid separator (25) is connected to the second test pipeline (42) through the fourth branch pipe (27), the liquid outlet of the gas-liquid separator (25) is connected to the first test pipeline (41) through the fifth branch pipe (28), and the second test pipeline (42) is connected to the inlet of the third heat exchange tube through the sixth branch pipe (29); wherein: the third branch pipe (26) is provided with a fifth control A valve (19), a liquid storage tank (21), a drying filter (22) and an expansion valve group, wherein the expansion valve group comprises at least a first expansion valve (23) and a second expansion valve (24) arranged in parallel; a sixth control valve (40) is arranged on the fourth branch pipe (27); a mass flow meter (32) and a seventh control valve (37) located downstream of the variable frequency pump (31) are arranged on the fifth branch pipe (28) in sequence; and an eighth control valve (46), a fourth temperature sensor (47) and a fourth pressure transmitter (48) are arranged on the sixth branch pipe (29).

9. The battery pack thermal management test system according to claim 8, characterized in that: The third branch pipe (26) and the sixth branch pipe (29) are connected via a first bypass pipe (60); the connection point between the first bypass pipe (60) and the third branch pipe (26) is located upstream of the fifth control valve (19); the connection point between the first bypass pipe (60) and the fourth branch pipe (27) is located between the sixth control valve (40) and the fourth temperature sensor (47); the first bypass pipe (60) is provided with a first bypass valve (20), a fifth temperature sensor (44) and a fifth pressure transmitter (45) in sequence; The third branch pipe (26) is connected to the fifth branch pipe (28) through a second bypass pipe (61); the connecting point of the second bypass pipe (61) and the third branch pipe (26) is located between the fifth control valve (19) and the liquid storage tank (21); the connecting point of the second bypass pipe (61) and the fifth branch pipe (28) is located downstream of the seventh control valve (37); and a second bypass valve (38) is provided on the second bypass pipe (61); The fifth branch pipe (28) and the sixth branch pipe (29) are connected via a third bypass pipe (62); a connection point between the third bypass pipe (62) and the fifth branch pipe (28) is located between the mass flow meter (32) and the seventh control valve (37); a connection point between the third bypass pipe (62) and the sixth branch pipe (29) is located between the eighth control valve (46) and the fourth temperature sensor (47); and a third bypass valve (39) is provided on the third bypass pipe (62).

10. The battery pack thermal management test system according to claim 1, characterized in that: The third heat exchange pipe is connected to the air return port of the variable frequency compressor (1) via an air intake pipe (30), and a gas-liquid separation element (55) is provided on the air intake pipe (30).

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