Thermal management system, thermal management method, battery system and electric aircraft

Abstract

The invention provides a thermal management system, a thermal management method, a battery system and an electric aircraft. The thermal management system comprises a water pump, a cooling part, a first expansion valve, a compressor, a second expansion valve and a condenser. The water pump, the cooling part and the battery pack are sequentially connected through pipelines to form a first loop, and the first heat exchange medium can circularly flow in the first loop, so that heat energy generated by the battery pack is transferred to the cooling part through the first heat exchange medium to be discharged. The first heat exchange medium and the second heat exchange medium can exchange heat in the cooling part and are used for transferring the heat absorbed by the first heat exchange medium to the second heat exchange medium. The cooling part, the compressor, the condenser and the first expansion valve are sequentially connected through pipelines to form a second loop, and the second heat exchange medium can circularly flow in the second loop so that heat absorbed by the second heat exchange medium can be discharged through the condenser. The second expansion valve is arranged on a first branch, and the two ends of the first branch are connected to the upstream side and the downstream side of the compressor respectively.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric aircraft, and particularly relates to a thermal management system, a thermal management method, a battery system and an electric aircraft. BACKGROUND

[0002] With the development of low-altitude economy, electric vertical takeoff and landing aircraft (Electric Vertical Takeoff and Landing, eVTOL for short) are gradually put into commercial operation, and its application scenarios include but are not limited to low-altitude sightseeing, urban passenger transport, cargo transport, emergency medical treatment, rescue services, etc.

[0003] The electric vertical takeoff and landing aircraft generates a large amount of heat during operation, especially the battery system generates a large amount of heat during takeoff, cruising and landing. If the heat cannot be effectively managed and dissipated in time, the temperature of the battery system may continue to rise and the discharge power may decrease, thereby affecting the normal function and performance of the electric aircraft. In some extreme cases, the continuous accumulation of heat may even cause the battery system to be out of control.

[0004] Since the battery pack itself has good heat preservation and insulation capacity, the heat generated inside cannot be directly exchanged with the external environment, and needs to be transferred through the thermal management system. However, in the low-temperature environment (for example, the ambient temperature is below zero), the cooling function of the ordinary thermal management system cannot normally operate, which will greatly reduce or even disable the thermal management capacity in the low-temperature environment. It is urgent to improve the thermal management system of the electric aircraft to adapt to the low-temperature environment. SUMMARY

[0005] The present application is made in view of the above state of the art. The purpose of the present application is to provide a thermal management system, a thermal management method, a battery system and an electric aircraft which can be applied to a low-temperature environment.

[0006] The application provides a heat management system for heat management of a battery pack of an electric aircraft, which comprises a water pump, a cooling unit, a first expansion valve, a compressor, a second expansion valve and a condenser, the water pump, the cooling unit and the battery pack are connected in sequence via pipelines to form a first loop, a first heat exchange medium can circulate in the first loop to transfer heat energy generated by the battery pack to the cooling unit via the first heat exchange medium. The first heat exchange medium and the second heat exchange medium can exchange heat in the cooling unit for transferring the heat absorbed by the first heat exchange medium to the second heat exchange medium, the cooling unit, the compressor, the condenser and the first expansion valve are connected in sequence via pipelines to form a second loop, the second heat exchange medium can circulate in the second loop to discharge the heat absorbed by the second heat exchange medium via the condenser. The second expansion valve is arranged in a first branch, and the two ends of the first branch are respectively connected to the upstream side and the downstream side of the compressor.

[0007] In one possible implementation, the heat management system further comprises a liquid storage unit, the liquid storage unit is arranged in a second branch, the second branch connects the first loop, so that the liquid storage unit can store the first heat exchange medium in the first loop; and / or further comprises a first heating unit, the first heating unit is arranged in the first loop, and the first heating unit is arranged upstream of the battery pack for heating the first heat exchange medium entering the battery pack.

[0008] In one possible implementation, the heat management system further comprises a second heating unit, the second heating unit is arranged in the first branch, and the second heating unit is arranged downstream of the second expansion valve between the second expansion valve and the compressor.

[0009] In one possible implementation, the heat management system further comprises one or more first temperature sensors, one or more second temperature sensors, one or more pressure sensors and one or more temperature and pressure sensors, the first temperature sensors are arranged in the first loop, and the second temperature sensors, the pressure sensors and the temperature and pressure sensors are arranged in the second loop.

[0010] In one possible implementation, the first heat exchange medium is a glycol solution, and / or the second heat exchange medium is tetrafluoroethane.

[0011] In one possible implementation, the inlet of the second expansion valve is connected between the compressor and the condenser, and the outlet of the second expansion valve is connected between the cooling unit and the compressor.

[0012] In a possible implementation, the thermal management system further comprises a gas-liquid separator, which is arranged in the second loop and between the cooling unit and the compressor, to prevent or reduce the liquid second heat exchange medium from entering the compressor.

[0013] The application also provides a thermal management method for thermal management of a battery pack of an electric aircraft, which is applicable to the aforementioned thermal management system, and the thermal management method comprises: S1: opening the second expansion valve to enable part of the second heat exchange medium to circulate between the first branch and the compressor to increase the pressure and temperature of the second heat exchange medium in the second loop; S2: after the pressure and temperature of the second heat exchange medium in the second loop reach the normal operation requirement, opening the first expansion valve, closing the second expansion valve or adjusting the opening degree of the second expansion valve to regulate the flow of the second heat exchange medium, so that the compressor drives the second heat exchange medium to circulate in the second loop, and the first heat exchange medium and the second heat exchange medium exchange heat in the cooling unit.

[0014] The application also provides a battery system, which comprises a battery pack and the aforementioned thermal management system of an electric aircraft.

[0015] In a possible implementation, the battery pack is a distributed battery pack, and the battery pack comprises a plurality of cell groups, each of which is independently connected to the first loop.

[0016] The application also provides an electric aircraft, which comprises the aforementioned thermal management system.

[0017] The thermal management system, the thermal management method, the battery system and the electric aircraft provided by the application can be applied to, for example, a low-temperature environment below zero degrees, and based on the double-loop design of the first loop and the second loop and the first branch connecting the upstream side and the downstream side of the compressor, the thermal management of the battery pack can be realized at a lower external temperature, the battery pack of the electric aircraft can be safely and stably operated in a low-temperature environment, and thus the environmental adaptability of the electric aircraft is improved. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 FIG. 1 is a structural schematic diagram of a battery system of an electric aircraft according to an embodiment of the application.

[0019] Figure 2 FIG. 2 is a structural schematic diagram of a first variant of the battery system of the electric aircraft according to an embodiment of the application.

[0020] Figure 3 FIG. 3 is a structural schematic diagram of a second variant of the battery system of the electric aircraft according to an embodiment of the application.

[0021] Reference Signs List

[0022] 10 water pump

[0023] 20 cooling section

[0024] 30 first heating section

[0025] 40 liquid storage section

[0026] 50 first expansion valve

[0027] 60 compressor

[0028] 71 second expansion valve

[0029] 72 second heating section

[0030] 73 gas-liquid separator

[0031] 80 condenser

[0032] 81 fan

[0033] 91 first temperature sensor

[0034] 92 second temperature sensor

[0035] 93 pressure sensor

[0036] 94 temperature-pressure sensor

[0037] 100 battery pack

[0038] 110 first cell group

[0039] 120 second cell group

[0040] 130 third cell group DETAILED DESCRIPTION

[0041] Exemplary embodiments of the present application are described below with reference to the accompanying drawings. It is to be understood that the specific description is merely for the purpose of illustration and that the application is not limited to the specific embodiments described herein. Rather, the specific description is intended to illustrate the application and its best mode for carrying out the application.

[0042] Embodiments of the present application provide a thermal management system (hereinafter, sometimes referred to simply as a thermal management system) that can be applied to thermal management (particularly, cooling) of a battery pack of an electric aircraft at a lower outside temperature (e.g., below zero).

[0043] The lower ambient temperature referred to in the present application is a temperature close to or lower than the minimum normal operating temperature of a conventional thermal management system / refrigeration system. For example, the low temperature can be a temperature lower than -7 degrees Celsius. The normal temperature environment referred to in the present application is the normal operating temperature range of a conventional thermal management system / refrigeration system. For example, the normal temperature can be a temperature higher than -7 degrees Celsius.

[0044] It can be understood that even at the above low temperature, the battery pack still generates a large amount of heat that cannot be dissipated or discharged when it is working, and the conventional thermal management system (air conditioning system) will cause the refrigerant to be excessively condensed due to the low temperature environment, the pressure in the system will decrease, and the saturation temperature of the refrigerant will be close to or even lower than the ambient temperature, thereby seriously affecting the cooling capacity of the conventional thermal management system, and even making it unable to start normally.

[0045] Specifically, as shown in Figure 1 and Figure 2 The thermal management system can include a water pump 10, a cooling part 20, a first expansion valve 50, a compressor 60, and a condenser 80. The water pump 10 and the cooling part 20 can be connected in sequence with the battery pack 100 via pipelines to form a first loop (a circulating flow path formed by connecting the head and tail). The pipelines of the first loop can be filled with a first heat exchange medium, and the first heat exchange medium can circulate in the first loop to transfer the heat energy generated by the battery pack 100 to the cooling part 20 via the first heat exchange medium to discharge the first loop. The flow direction of the first heat exchange medium in the first loop can be to flow through the battery pack 100, the water pump 10, the cooling part 20, and the battery pack 100 in sequence, thereby forming a flow circulation.

[0046] Preferably, the first heat exchange medium can be a glycol solution, which has a lower freezing point (as low as -60 degrees Celsius) so that the first loop can operate at a lower ambient temperature and the glycol solution is less likely to damage the pipeline due to liquid freezing. At the same time, the glycol solution also has a higher specific heat capacity and good thermal conductivity.

[0047] Preferably, the water pump 10 can be an electronic water pump, which is driven by electricity to transfer liquid. Compared with a traditional water pump, the electronic water pump can more accurately control the flow of the heat exchange medium and improve the temperature management efficiency.

[0048] The first heat exchange medium can absorb the heat released by the battery pack 100 when the battery pack 100 is working, and the cooling part 20 can cool the first heat exchange medium passing through it, i.e., discharge the heat absorbed by the first heat exchange medium. Further, the first heat exchange medium can transfer the heat absorbed by it to the second heat exchange medium in the cooling part 20, i.e., the first heat exchange medium and the second heat exchange medium can exchange heat in the cooling part 20, so that the heat generated by the battery pack 100 is discharged from the first loop.

[0049] The cooling unit 20, the compressor 60, the condenser 80 and the first expansion valve 50 can be connected in sequence via pipelines to form a second loop. The pipelines of the second loop can be filled with a second heat exchange medium, which can circulate in the second loop to discharge the heat absorbed by the second heat exchange medium via the condenser 80. The flow direction of the second heat exchange medium in the second loop can be sequentially flowing through the cooling unit 20, the compressor 60, the condenser 80, the first expansion valve 50 and the cooling unit 20 to form a flow cycle.

[0050] Specifically, the cooling unit 20 can include a first heat exchange medium passage and a second heat exchange medium passage. The first heat exchange medium passage can be connected to the first loop, and the second heat exchange medium passage can be connected to the second loop. The first heat exchange medium passage and the second heat exchange medium passage are not directly connected, that is, the first heat exchange medium passage and the second heat exchange medium passage do not form material exchange. The first heat exchange medium passage and the second heat exchange medium passage can be adjacent to each other so that the first heat exchange medium and the second heat exchange medium exchange heat.

[0051] The compressor 60 can suck in the second heat exchange medium, compress it and then discharge it. The pressure and temperature of the second heat exchange medium processed by the compressor 60 will be increased, that is, the compressor 60 can increase the system pressure in the second loop. The second heat exchange medium (usually high-pressure gas) processed by the compressor 60 can release heat in the condenser 80 and condense into a liquid state. The heat generated by the battery pack 100 is released to the external environment through the condenser 80. The second heat exchange medium (usually high-pressure liquid) condensed in the condenser 80 can enter the cooling unit 20 to absorb heat from the first heat exchange medium after being decompressed and cooled by the first expansion valve 50. The second heat exchange medium (usually low-pressure gas) that absorbs heat can enter the compressor 60 to form a recycling use of the second heat exchange medium.

[0052] Optionally, the thermal management system can further include a fan 81 adjacent to the condenser 80, for blowing out the heat released by the second heat exchange medium at the condenser 80, improving the heat dissipation efficiency of the condenser 80.

[0053] In order to adapt to lower external temperature, the thermal management system can further include a second expansion valve 71, which can be arranged in the first branch. The two ends of the first branch can be connected to the upstream side and the downstream side of the compressor 60, respectively. At lower external temperature, the second loop can not be able to start normal work due to too low pressure. At this time, the second expansion valve 71 can be opened first, so that the compressor 60 first compresses (increases temperature and pressure) the second heat exchange medium in the first branch, and then quickly increases the pressure and temperature in the second loop, so that the second loop overcomes the low temperature and starts to work.

[0054] Preferably, the inlet of the second expansion valve 71 (or the inlet of the first branch) can be connected between the compressor 60 and the condenser 80, and the outlet of the second expansion valve 71 (or the outlet of the first branch) can be connected between the cooling part 20 and the compressor 60.

[0055] Preferably, the first expansion valve 50 and the second expansion valve 71 can be electronic expansion valves, which can include controllers, actuators, sensors, etc., and can have functions of controlling on-off, throttling, pressure reduction, etc. The specific structures of the first expansion valve 50 and the second expansion valve 71 can be different. It can be understood that the specific structures of the first expansion valve 50 and the second expansion valve 71 can be determined according to different on-off, throttling and pressure reduction requirements of the second loop and the first branch. For example, the first expansion valve 50 can have good throttling, pressure reduction and temperature reduction capabilities; the second expansion valve 71 can have good on-off control capabilities, and the second expansion valve 71 can have higher flow passing capacity than the first expansion valve 50 to meet the requirement of rapidly increasing the pressure and temperature of the second loop system.

[0056] Preferably, the thermal management system can further include a liquid storage part 40, which can be arranged in the second branch and can be connected to the first loop to store the first heat exchange medium in the first loop. With the change of the temperature of the first loop, the volume of the first heat exchange medium in the first loop can change due to thermal expansion and contraction, thereby changing the internal pressure of the first loop. The arrangement of the liquid storage part 40 can balance the volume change of the first heat exchange medium, i.e., store part of the first heat exchange medium when the volume of the first heat exchange medium increases, and release part of the first heat exchange medium when the volume of the first heat exchange medium decreases, thereby maintaining the relative stability of the internal pressure of the first loop.

[0057] Preferably, the thermal management system can further include a first heating part 30, which can be arranged in the first loop and upstream of the battery pack 100 (in the flow direction of the first heat exchange medium in the first loop) to heat the first heat exchange medium entering the battery pack 100. In some cases, such as starting the battery pack 100 in a low-temperature environment, it can be necessary to heat the battery pack 100 first. The arrangement of the first heating part 30 can heat the first heat exchange medium entering the battery pack 100, thereby achieving the heating of the battery pack.

[0058] Preferably, as shown in FIG. 1, the first branch can be connected between the second expansion valve 71 and the cooling part 20, and the second branch can be connected between the first expansion valve 50 and the condenser 80. Figure 2As shown, the thermal management system can further include a second heating portion 72, which can be arranged in the first branch, and the second heating portion 72 can be arranged downstream of the second expansion valve 71 (in the flow direction of the second heat exchange medium in the first branch). When starting the aforementioned first branch at a lower temperature, the compressor 60 can have a greater operating load and speed due to the lower temperature of the second heat exchange medium. Arranging the second heating portion 72 to heat the second heat exchange medium entering the compressor 60 can reduce the operating load and speed of the compressor 60, thereby reducing the operating noise of the compressor 60 in a low-temperature environment.

[0059] The thermal management system can further include one or more of one or more first temperature sensors 91, one or more second temperature sensors 92, one or more pressure sensors 93, and one or more temperature and pressure sensors 94.

[0060] The first temperature sensor 91 can be arranged in the first circuit, and for example, the first temperature sensor 91 can be arranged upstream and / or downstream of the battery pack 100, for monitoring the temperature of the battery pack 100 and the first heat exchange medium.

[0061] The second temperature sensor 92 can be arranged in the second circuit, and for example, the second temperature sensor 92 can be arranged upstream and / or downstream of the compressor 60, for monitoring the temperature of the second heat exchange medium.

[0062] The pressure sensor 93 can be arranged in the second circuit, and for example, the pressure sensor 93 can be arranged upstream of the compressor 60, for monitoring the pressure of the second heat exchange medium.

[0063] The temperature and pressure sensor 94 can be arranged in the second circuit, and for example, the temperature and pressure sensor 94 can be arranged downstream of the condenser 80, for monitoring the pressure and temperature of the second heat exchange medium.

[0064] Preferably, the second heat exchange medium can be tetrafluoroethane R134a.

[0065] Below, the operation mode of the aforementioned thermal management system is exemplarily introduced.

[0066] In a normal temperature environment (above -7 degrees Celsius), when the battery pack 100 needs to be cooled, the water pump 10 can be turned on to drive the flow of the first heat exchange medium. The compressor 60 is turned on to drive the flow of the second heat exchange medium. The first heat exchange medium and the second heat exchange medium exchange heat in the cooling portion 20. In this process, the second expansion valve 71 is not turned on, and the first branch is not communicated with the compressor 60.

[0067] When the battery pack 100 needs to be cooled in a low temperature environment (for example, -7 degrees Celsius), the second expansion valve 71 is first opened to make part of the second heat exchange medium circulate between the first branch and the compressor 60. This process will gradually increase the pressure and temperature of the second heat exchange medium in the second loop. When the second loop meets the required pressure and temperature for normal operation, the first expansion valve 50 is opened, and the compressor 60 drives the second heat exchange medium to flow in the entire second loop, thereby realizing heat exchange between the first heat exchange medium and the second heat exchange medium in the cooling part 20.

[0068] Further, as shown in Figure 3 The heat management system can further include a gas-liquid separator 73, which can be arranged in the second loop. The gas-liquid separator 73 can separate the gas and liquid in the second heat exchange medium entering it, so that the gaseous second heat exchange medium enters the compressor 60, and the liquid second heat exchange medium can remain in the gas-liquid separator 73 to prevent or reduce the liquid second heat exchange medium from entering the compressor 60, thereby prolonging the service life of the compressor 60. It can be understood that the compressor 60 cannot compress liquid, and the liquid entering the compressor can damage the compression force receiving parts such as valve plates and pistons in the compressor (this phenomenon is also called "liquid hammer").

[0069] Specifically, the gas-liquid separator 73 can be arranged upstream of the compressor 60, i.e., the gas-liquid separator 73 can be arranged between the cooling part 20 and the compressor 60 to prevent or reduce the liquid second heat exchange medium from entering the compressor 60. The gas-liquid separator 73 is mainly used to process the liquid or gas-liquid mixed second heat exchange medium in the second loop (from the cooling part 20 to the compressor 60) under low temperature conditions. However, under normal temperature conditions, the second heat exchange medium in the second loop from the cooling part 20 to the compressor 60 mainly exists in the form of low-pressure gas and does not need (basically does not need) the gas-liquid separator 73 to perform gas-liquid separation work.

[0070] It can be understood that during the initial period of starting the heat management system under low temperature conditions, the gas-liquid separator 73 can collect liquid second heat exchange medium, which will gradually be converted into gaseous second heat exchange medium as the temperature and pressure in the second loop rise. Therefore, the gas-liquid separator 73 can not need to be provided with a liquid discharge structure.

[0071] Preferably, the gas-liquid separator 73 can be a gravity sedimentation type gas-liquid separator. This type of gas-liquid separator uses a gravity field to separate liquid and gas, and can remain in working condition without needing to be controlled separately to open or close. That is, the gas-liquid separator 73 can mainly function during the initial period of starting in a low temperature environment, and in other working conditions, the gas-liquid separator 73 can serve as a safety device to prevent the occurrence of liquid hammer phenomenon.

[0072] It can be understood that the thermal management system provided by the embodiment can not only manage the battery pack of the electric aircraft, but also exchange heat with other devices of the electric aircraft that need to be managed. For example, the passenger cabin and / or the cockpit of the electric aircraft can be provided with an air conditioning system, and the thermal management system can also be connected to the air conditioning system and exchange heat with the air conditioning system to help adjust the temperature of the passenger cabin and / or the cockpit.

[0073] Based on the above thermal management system, the embodiment of the present application also provides a thermal management method suitable for managing the battery pack at low temperature. The thermal management method is suitable for the above-mentioned thermal management system, and the thermal management method comprises the following steps:

[0074] S1: open the second expansion valve 71, and make part of the second heat exchange medium circulate between the first branch and the compressor 60 to increase the pressure and temperature of the second heat exchange medium in the second circuit;

[0075] S2: after the pressure and temperature of the second heat exchange medium in the second circuit reach the normal operation requirement, open the first expansion valve 50, close the second expansion valve 71 or adjust the opening degree of the second expansion valve 71 to adjust the flow of the second heat exchange medium through the first branch, so that the compressor 60 drives the second heat exchange medium to circulate in the second circuit, and the first heat exchange medium and the second heat exchange medium exchange heat in the cooling part 20.

[0076] It can be understood that since the operation of the first circuit is not easily affected by low temperature, the start time of the first circuit in a low temperature environment can be relatively flexible.

[0077] The embodiment of the present application also provides a battery system suitable for an electric aircraft, which can comprise the above-mentioned thermal management system of the electric aircraft and a battery pack 100.

[0078] Preferably, the battery pack 100 can be a distributed battery pack, which can comprise a plurality of cell groups. For example, as shown in Figure 1 and Figure 2 The battery pack 100 can comprise a first cell group 110, a second cell group 120 and a third cell group 130. Each cell group can comprise one or more cells.

[0079] Inside the battery pack 100, the plurality of cell groups can form a parallel structure, so that each cell group can be independently connected to the first circuit, and the first heat exchange medium can flow through each cell group in parallel instead of sequentially passing through the plurality of cell groups, which is beneficial to the same or similar thermal management effect of each cell group.

[0080] The above-mentioned thermal management system and battery system of the electric aircraft are particularly suitable for electric vertical take-off and landing aircraft, but the range of electric aircrafts to which they can be applied is not limited to this.

[0081] The application also provides an electric aircraft, which can comprise the thermal management system of the electric aircraft and / or the battery system of the electric aircraft described above.

[0082] The thermal management system of the electric aircraft, the battery system of the electric aircraft and the electric aircraft provided in the foregoing embodiments of the application are particularly suitable for use in a low-temperature environment, but this does not mean that the technical solutions are limited to use in a low-temperature environment.

[0083] The following briefly describes some beneficial effects of the foregoing embodiments of the application.

[0084] The thermal management system, the thermal management method, the battery system and the electric aircraft provided by the embodiments of the application can realize thermal management of the battery pack in a low-temperature environment based on the double-circuit design of the first circuit and the second circuit and the first branch connecting the upstream side and the downstream side of the compressor, thereby ensuring that the battery pack of the electric aircraft can operate safely and stably in a low-temperature environment, and further improving the environmental adaptability of the electric aircraft.

[0085] It can be understood that, in the present application, when the number of components or members is not particularly limited, the number can be one or more, and the plurality herein refers to two or more. For the case where the number of components or members is described as a specific number such as two, three, four, etc. in the drawings and / or the description, the specific number is generally exemplary rather than limiting, and it can be understood as a plurality, i.e. two or more, but this does not mean that the present application excludes the case of one.

[0086] It should be understood that the above embodiments are only exemplary and are not used to limit the present application. Those skilled in the art can make various modifications and changes to the above embodiments under the teaching of the present application without departing from the scope of the present application.

Claims

1. A thermal management system for thermal management of a battery pack (100) of an electric aircraft, characterized in that, It includes a water pump (10), a cooling unit (20), a first expansion valve (50), a compressor (60), a second expansion valve (71), and a condenser (80). The water pump (10), the cooling unit (20), and the battery pack (100) are connected in sequence via pipelines to form a first loop. A first heat exchange medium can circulate within the first loop to transfer the heat energy generated by the battery pack (100) to the cooling unit (20) for discharge. The first heat exchange medium and the second heat exchange medium can exchange heat within the cooling section (20), for transferring the heat absorbed by the first heat exchange medium to the second heat exchange medium. The cooling unit (20), the compressor (60), the condenser (80), and the first expansion valve (50) are connected in sequence via pipelines to form a second circuit. The second heat exchange medium can circulate within the second circuit to discharge the heat absorbed by the second heat exchange medium through the condenser (80). The second expansion valve (71) is located in the first branch, and the two ends of the first branch are respectively connected to the upstream side and the downstream side of the compressor (60).

2. The thermal management system according to claim 1, characterized in that, It also includes a liquid storage section (40), which is disposed in a second branch connected to the first circuit, so that the liquid storage section (40) can store the first heat exchange medium in the first circuit; and / or It also includes a first heating element (30), which is disposed in the first circuit and is disposed upstream of the battery pack (100) for heating the first heat exchange medium that will enter the battery pack (100).

3. The thermal management system according to claim 1, characterized in that, It also includes a second heating section (72), which is disposed on the first branch and is disposed downstream of the second expansion valve (71), located between the second expansion valve (71) and the compressor (60).

4. The thermal management system according to claim 1, characterized in that, It also includes one or more first temperature sensors (91), one or more second temperature sensors (92), one or more pressure sensors (93), and one or more temperature and pressure sensors (94). The first temperature sensor (91) is located in the first circuit. The second temperature sensor (92), the pressure sensor (93), and the temperature-pressure sensor (94) are disposed in the second circuit.

5. The thermal management system according to claim 1, characterized in that, The first heat exchange medium is an ethylene glycol solution, and / or the second heat exchange medium is tetrafluoroethane.

6. The thermal management system according to claim 1, characterized in that, The inlet of the second expansion valve (71) is connected between the compressor (60) and the condenser (80), and the outlet of the second expansion valve (71) is connected between the cooling section (20) and the compressor (60).

7. The thermal management system according to claim 1, characterized in that, It also includes a gas-liquid separator (73), which is disposed in the second circuit and between the cooling section (20) and the compressor (60) to prevent or reduce the entry of the liquid second heat exchange medium into the compressor (60).

8. A thermal management method for thermal management of a battery pack in an electric aircraft, characterized in that, Applicable to the thermal management system of any one of claims 1 to 7, The thermal management method includes: S1: Open the second expansion valve (71) to allow a portion of the second heat exchange medium to circulate between the first branch and the compressor (60) in order to increase the pressure and temperature of the second heat exchange medium in the second circuit; S2: After the pressure and temperature of the second heat exchange medium in the second circuit reach the normal operation requirements, the first expansion valve (50) is opened and the second expansion valve (71) is closed or the opening degree of the second expansion valve (71) is adjusted to regulate the flow rate of the second heat exchange medium, so that the compressor (60) drives the second heat exchange medium to circulate in the second circuit, so that the first heat exchange medium and the second heat exchange medium form a heat exchange in the cooling section (20).

9. A battery system, characterized in that, It includes a battery pack (100) and a thermal management system for the electric aircraft according to any one of claims 1 to 6.

10. The battery system according to claim 9, characterized in that, The battery pack (100) is a distributed battery pack, which includes multiple cell groups, each of which is independently connected to the first circuit.

11. An electric aircraft, characterized in that, The thermal management system includes any one of claims 1 to 7.

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