Thermal management system, method of controlling a thermal management system, and controller

Abstract

The application relates to a heat management system, a control method and a controller of the heat management system, the heat management system comprising an expansion valve, the heat management system being used for heat management of a cabin, the method comprising the following steps: determining a current heat exchange capacity of the heat management system; determining a required heat exchange capacity of the cabin in a working mode and a preset capacity interval in which the required heat exchange capacity is located, obtaining a control strategy of the heat management system, wherein the control strategies associated with different preset capacity intervals are different; and adjusting the opening degree of the expansion valve of the heat management system according to the control strategy, so that the current heat exchange capacity approximates to the required heat exchange capacity. According to the application, the heat management system can be controlled in intervals, and the optimal efficiency in the intervals under various working conditions is considered, so that the energy efficiency of the heat management system is maximized.

Description

Technical Field

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

[0002] The inventors of this application discovered in their research that, due to the lack of engineering experience in vehicle thermal management systems and the scarcity of control strategies among major enterprises, it is difficult to achieve optimal performance of the thermal management system under various operating conditions. Summary of the Invention

[0003] The present invention provides a thermal management system, a control method for the thermal management system, and a controller, which can control the thermal management system and take into account the optimal performance under various operating conditions.

[0004] In a first aspect, this application provides a thermal management system control method, the thermal management system including an expansion valve, the thermal management system performing thermal management on the cabin, the method comprising the following steps:

[0005] Determine the current heat exchange capacity of the thermal management system;

[0006] By determining the required heat exchange capacity of the cabin under the operating mode and the preset capacity range in which the required heat exchange capacity falls, a control strategy for the thermal management system is obtained, wherein different preset capacity ranges are associated with different control strategies; and

[0007] The opening degree of the expansion valve of the thermal management system is adjusted according to the control strategy so that the current heat exchange capacity approaches the required heat exchange capacity.

[0008] In the above scheme, the current control strategy of the system is obtained by determining the required heat exchange capacity of the cabin and the preset capacity range in which the required heat exchange capacity is located. In this application, the control strategy of the thermal management system is different in different preset capacity ranges. It can realize zoned control according to different capacity ranges, adjust the control strategy in real time, and adjust the opening of the expansion valve according to the control strategy so that the current heat exchange capacity is close to the required heat exchange capacity. The thermal management system can adapt to energy efficiency control under different operating conditions and achieve maximum energy efficiency.

[0009] Secondly, this application provides a thermal management system, which includes a compressor, a condenser, an expansion valve, and an evaporator, and performs thermal management on the cabin; the thermal management system also includes a controller, which is used for:

[0010] Determine the current heat exchange capacity of the thermal management system;

[0011] By determining the required heat exchange capacity of the cabin under the operating mode and the preset capacity range in which the required heat exchange capacity falls, a control strategy for the thermal management system is obtained, wherein different preset capacity ranges are associated with different control strategies; and

[0012] The opening degree of the expansion valve of the thermal management system is adjusted according to the control strategy so that the current heat exchange capacity approaches the required heat exchange capacity.

[0013] The thermal management system provided in this application obtains the current control strategy of the system by determining the required heat exchange capacity of the cabin and the preset capacity range in which the required heat exchange capacity is located. This results in different control strategies for the thermal management system in different preset capacity ranges. It can realize zoned control according to different capacity ranges and adjust the control strategy in real time, so that the thermal management system can adapt to energy efficiency control under different operating conditions and achieve maximum energy efficiency.

[0014] Thirdly, this application provides a controller that executes the control method of the above-described thermal management system. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1a This is a schematic diagram of the circulation loop of the thermal management system in cooling mode in the embodiments of this application;

[0017] Figure 1b This is a schematic diagram of the circulation loop of the thermal management system in heating mode in the embodiments of this application;

[0018] Figure 2 This is a flowchart illustrating a control method for a thermal management system provided in an embodiment of this application;

[0019] Figure 3 This is a schematic diagram of different preset interval control strategies in the embodiments of this application. Detailed Implementation

[0020] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0021] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0022] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0023] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0024] It should be understood that although the terms first, second, third, etc., may be used to describe terminals in the embodiments of the present invention, these terminals should not be limited to these terms. These terms are only used to distinguish terminals from each other. For example, without departing from the scope of the embodiments of the present invention, a first terminal may also be referred to as a second terminal, and similarly, a second terminal may also be referred to as a first terminal.

[0025] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0026] This application relates to a thermal management system. The thermal management system can be applied in various application scenarios requiring thermal management, such as in the onboard air conditioning system of electric vehicles. The thermal management system includes a compressor M1, an indoor heat exchanger M2, an expansion valve M3, and an outdoor heat exchanger M4, with refrigerant flowing inside each component. The thermal management system of this application is suitable for various types of refrigerants. Optionally, the refrigerant is CO2. The thermal management system is used for thermal management of the cabin, regulating the temperature of the air inside the cabin. When the thermal management system is applied to a vehicle, the cabin is the passenger compartment.

[0027] like Figure 1aAs shown, this is the circulation loop in cooling mode. The high-temperature, high-pressure refrigerant, compressed by compressor M1, enters the outdoor heat exchanger M4, where it undergoes a transcritical cycle. The refrigerant temperature gradually decreases while the pressure remains constant. After flowing through expansion valve M3, it becomes a low-temperature, low-pressure gas-liquid two-phase mixture, which then enters the indoor heat exchanger M2 to absorb heat before returning to compressor M1, thus forming the refrigeration cycle. The indoor heat exchanger M2 exchanges heat with the air inside the cabin, acting as an evaporator. The outdoor heat exchanger M4 exchanges heat with the air outside the cabin, acting as a condenser, thereby achieving cabin cooling.

[0028] like Figure 1b As shown, this is the circulation loop in heating mode. The high-temperature, high-pressure refrigerant, compressed by compressor M1, first enters the indoor heat exchanger M2 to release heat, then flows through expansion valve M3 and enters the outdoor heat exchanger M4 to absorb heat, forming a heating cycle. The indoor heat exchanger M2 exchanges heat with the air inside the cabin and acts as a condenser, while the outdoor heat exchanger M4 exchanges heat with the air outside the cabin and acts as an evaporator, thereby achieving heating of the cabin.

[0029] The thermal management system also includes a controller, which controls the components in the thermal management system according to the control method described below, enabling the thermal management system to adapt to energy efficiency control under different operating conditions and achieve maximum energy efficiency. Specifically, the controller is used to operate the control method described below for the thermal management system.

[0030] The control method of the thermal management system in this application embodiment is applicable to both the above-described cooling mode and the above-described heating mode.

[0031] like Figure 2 One embodiment of this application provides a control method for a thermal management system, comprising the following steps:

[0032] S10, Determine the current heat exchange capacity of the thermal management system;

[0033] S20, determine the required heat exchange capacity of the cabin under the working mode and the preset capacity range in which the required heat exchange capacity is located, and obtain the control strategy of the thermal management system, wherein different preset capacity ranges are associated with different control strategies; and

[0034] S30, adjusts the opening of the expansion valve of the thermal management system according to the control strategy, so that the current heat exchange capacity is close to the required heat exchange capacity.

[0035] In the aforementioned scheme, the current control strategy of the system is obtained by determining the required heat exchange capacity of the cabin and the preset capacity range in which the required heat exchange capacity falls. In this application, the control strategy of the thermal management system differs within different preset capacity ranges. It can achieve zoned control based on different capacity ranges, adjust the control strategy in real time, and regulate the opening of the expansion valve according to the control strategy, so that the current heat exchange capacity approaches the required heat exchange capacity. The thermal management system can adapt to energy efficiency control under different operating conditions, thereby maximizing energy efficiency.

[0036] Specifically, the thermal management system operates in either cooling or heating mode. The required heat exchange capacity of the cabin is related to factors such as internal cabin demand parameters, external environmental parameters, and cabin operating status parameters. The current heat exchange capacity of the thermal management system is related to its operating status, including factors such as compressor speed, compressor inlet and outlet pressures, and expansion valve opening. Comparing the required heat exchange capacity with the system's current heat exchange capacity reveals the current energy demand of the thermal management system.

[0037] Specifically, S10 determines the current heat exchange capacity of the thermal management system, including:

[0038] Based on the operating status of the condenser, evaporator, and compressor, the current heat exchange capacity of the thermal management system is obtained.

[0039] Specifically, the current heat exchange capacity Q of the thermal management system is affected. Ref The physical variables include condenser outlet temperature, evaporator outlet temperature, compressor suction pressure, compressor discharge pressure, and compressor speed. The current heat exchange capacity of the thermal management system refers to the heat exchange capacity provided to the cabin under the current state of the thermal management system; specifically, it is the heating or cooling capacity provided to the cabin by the indoor heat exchangers.

[0040] S20, determine the required heat exchange capacity of the cabin under the working mode and the preset capacity range in which the required heat exchange capacity is located, including:

[0041] S21. Obtain the required heat exchange capacity of the cabin based on the internal demand parameters, external environmental parameters, and operating status parameters of the cabin.

[0042] S22, compare the demand heat exchange capacity with multiple preset capacity reference values ​​to determine the preset capacity range in which the demand heat exchange capacity falls. The preset capacity range is selected from any one of the first preset range, the second preset range, the third preset range, and the fourth preset range. Wherein, if the demand heat exchange capacity ≤ Q1, the demand heat exchange capacity is in the fourth preset range; if Q1 < demand heat exchange capacity ≤ Q2, the demand heat exchange capacity is in the third preset range; if Q2 < demand heat exchange capacity ≤ Q3, the demand heat exchange capacity is in the second preset range; if Q3 < demand heat exchange capacity ≤ Q4, the demand heat exchange capacity is in the first preset range; and if Q4 > Q3 > Q2 > Q1.

[0043] In some specific implementations, the internal requirements parameters of the cabin include the target cabin temperature and target cabin humidity. The external environmental parameters of the cabin include ambient temperature and sunlight intensity. The cabin operating status parameters include operating speed, number of passengers in the cabin, internal cabin volume, and cabin sealing.

[0044] Specifically, the required heat exchange capacity Q of the cabin is calculated. c Dimensionless parameter methods can be used. It should be noted that dimensionless parameters refer to physical variables that affect the calculated heat exchange capacity of the cabin, such as the target cabin temperature, target cabin humidity, ambient temperature, sunlight intensity, operating speed, number of passengers in the cabin, cabin volume, and cabin sealing.

[0045] Q c =f(DAT, ambT, Gascooler OutT, Eva OutT, Lp, LpStaturationT)

[0046] Among them, Q c For the required heat exchange capacity, DAT is the target temperature of the chamber, ambT is the ambient temperature, Gascooler OutT is the condenser outlet temperature, Eva OutT is the evaporator outlet temperature, Lp is the compressor inlet pressure, and LpStaturationT is the saturation temperature corresponding to the compressor inlet pressure.

[0047] S22, compare the demand heat exchange capacity with multiple preset capacity reference values ​​to determine the preset capacity range in which the demand heat exchange capacity is located.

[0048] In one embodiment of this application, a first reference value Q1, a second reference value Q2, a third reference value Q3, and a fourth reference value Q4 can be set, where Q4 > Q3 > Q2 > Q1. In other embodiments, the number of reference values ​​can be other numbers.

[0049] like Figure 3 As shown, when Q3<Q cIf Q2 < Q4, the required heat exchange capacity of the cabin is within the first preset range, and the control strategy associated with the first preset range is determined to be the ultimate pressure control strategy. c If Q1 < Q3, the required heat exchange capacity of the cabin falls within the second preset range, and the control strategy associated with this second preset range is determined to be the optimal pressure control strategy. c ≤Q2, the required heat exchange capacity of the cabin is within the third preset range, and the control strategy associated with the third preset range is determined to be the refrigerant temperature control strategy. When Q c If the required heat exchange capacity of the cabin is ≤Q1, it falls within the fourth preset range. The control strategy associated with this fourth preset range is determined to be a refrigerant dry / wet control strategy. By determining the range within which the cabin's required heat exchange capacity falls, the control strategy of the thermal management system is adaptively adjusted to maximize energy efficiency.

[0050] Furthermore, in step S30, the opening of the expansion valve of the thermal management system is adjusted according to the control strategy so that the current heat exchange capacity approaches the required heat exchange capacity.

[0051] Operating Condition 1: When Q c If the control strategy of the thermal management system is a refrigerant dry / wet control strategy, then step S30 specifically includes:

[0052] The compressor speed is controlled to the minimum speed, and the opening of the expansion valve is adjusted to change the dryness of the refrigerant at the condenser outlet, so that the actual outlet air temperature of the thermal management system reaches the target temperature of the cabin.

[0053] When the required heat exchange capacity of the cabin is within the aforementioned fourth preset range, it indicates that the cabin's heat exchange demand is very small, the compressor speed reaches its minimum speed, and the compressor outlet pressure remains constant, i.e., it reaches the saturation pressure state. The refrigerant at the condenser outlet enters the gas-liquid two-phase region. To ensure comfort within the cabin, it is only necessary to adjust the opening of the expansion valve to change the dryness of the refrigerant at the condenser outlet, where the dryness of the refrigerant is the volume ratio of the gas and liquid phases of the refrigerant.

[0054] When the refrigerant's gaseous phase proportion is greater than its liquid phase proportion (more gaseous, less liquid), the refrigerant has a higher dryness, resulting in a greater heat transfer capacity of the condenser. Conversely, when the refrigerant's gaseous phase proportion is less than its liquid phase proportion (less gaseous, more liquid), the refrigerant has a lower dryness, resulting in a lower heat transfer capacity of the condenser. Therefore, by changing the dryness of the refrigerant at the condenser outlet, the condenser's heat exchange capacity can be altered, thereby affecting the actual outlet air temperature of the indoor heat exchanger in the thermal management system, ensuring that the actual outlet air temperature reaches the target temperature of the cabin.

[0055] In a thermal management system, the refrigerant dryness at the outlet of the condenser corresponds to that at the outlet of the evaporator. Adjusting the refrigerant dryness at the outlet of the condenser will adjust the refrigerant dryness at the outlet of the evaporator.

[0056] In this application, the required heat exchange capacity within the aforementioned fourth preset range adopts a refrigerant dry / wet control strategy, and the compressor speed can be kept at the lowest speed, thereby achieving the goal of meeting the heat exchange requirements of the cabin while reducing the system's energy consumption.

[0057] Operating Condition 2: When Q1 < Q c ≤Q2, the control strategy of the thermal management system is the refrigerant temperature control strategy.

[0058] When the thermal management system is in either a cooling or heating cycle, step S30 specifically includes:

[0059] The actual subcooling of the condenser is calculated based on its outlet temperature and pressure, and the difference between the actual subcooling and the target subcooling of the thermal management system is calculated. A PID calculation is performed on this difference, and the opening of the expansion valve is adjusted according to the calculation result to bring the difference close to zero, meaning the actual subcooling is infinitely close to the target subcooling. Optionally, the target subcooling of the system is the minimum allowable subcooling, which is a value between 3℃ and 10℃. It should be understood that in practical applications, adjusting the difference to zero is difficult to achieve; therefore, an error range can be set, and the difference can be adjusted to within this range. Optionally, the error range value is 0±1°.

[0060] The actual subcooling of the condenser is the difference between the saturated liquid temperature corresponding to the real-time outlet pressure of the condenser and the real-time outlet temperature of the condenser. Since the pressure drop of the condenser is relatively small compared to that of the evaporator, the outlet pressure of the compressor can be approximated as the outlet pressure of the condenser. That is, the difference between the saturated liquid temperature corresponding to the compressor outlet pressure and the outlet temperature of the condenser is the subcooling.

[0061] For example, if the compressor outlet pressure is 10 MPa, corresponding to a saturated liquid temperature of 30°C, and the condenser outlet temperature is 25°C, then the actual subcooling of the condenser is 5°C, while the target subcooling of the thermal management system is 3°C, resulting in a difference of 2°C. In this case, it is only necessary to adjust the opening of the expansion valve to make the actual subcooling of the condenser infinitely close to the target subcooling.

[0062] In a thermal management system, the actual subcooling of the condenser corresponds to the actual superheat of the evaporator. Adjusting the actual subcooling of the condenser can adjust the actual superheat of the evaporator.

[0063] Understandably, the opening of the expansion valve can also be adjusted according to the actual superheat of the evaporator. Specifically, step S30 includes:

[0064] The actual superheat of the evaporator is calculated based on its outlet temperature and pressure, and the difference between the actual superheat and the target superheat of the thermal management system is calculated. A PID calculation is performed on this difference, and the opening of the expansion valve is adjusted according to the calculation results to bring the difference close to zero. The evaporator superheat is the difference between the saturated liquid temperature corresponding to the real-time outlet pressure of the evaporator and the real-time outlet temperature of the evaporator, and the saturated liquid temperature corresponding to the real-time outlet pressure of the evaporator corresponds to the inlet pressure of the compressor.

[0065] It is important to understand that when adjusting the opening of the expansion valve based on the actual subcooling of the condenser, if the actual superheat of the evaporator is too high, it will cause the compressor discharge temperature to be too high, deteriorate the compressor's operating conditions, and reduce its lifespan. Therefore, it is necessary to adjust the actual superheat of the evaporator at the same time to ensure that the thermal management system operates in a safe state.

[0066] Operating condition 3: When Q2 < Q c If the thermal management system's control strategy is the optimal working pressure control strategy (≤Q3), then step S30 specifically includes:

[0067] The optimal operating pressure of the thermal management system is determined based on the operating conditions of the condenser and the evaporator.

[0068] Adjust the opening of the expansion valve to bring the condenser outlet pressure to the optimal operating pressure.

[0069] Understandably, the optimal operating pressure of the condenser varies with the condenser outlet temperature, the evaporator inlet and outlet temperatures, and the evaporator outlet pressure. For example, in a refrigeration cycle, the optimal operating pressure can be obtained through experimental simulation. It should be noted that the thermal management system achieves maximum energy efficiency at the optimal operating pressure, and adopting an optimal operating pressure control strategy can reduce system energy consumption.

[0070] Operating Condition 4: When Q3 < Q c If the control strategy of the thermal management system is the ultimate pressure control strategy, then step S30 specifically includes: ≤Q4

[0071] Adjust the opening of the expansion valve to increase the outlet pressure of the condenser to a value higher than the preset maximum outlet pressure, but lower than the limit operating pressure of the thermal management system.

[0072] Understandably, within this range, the cabin's required heat exchange capacity is very high, and the compressor speed reaches its maximum. However, the thermal management system still struggles to meet the actual heat exchange capacity required by the cabin. Therefore, it is necessary to increase the operating pressure within the system's allowable pressure range. Since the opening of the expansion valve is adjusted in real time according to the operating pressure, increasing the opening of the expansion valve will increase the condenser's outlet pressure to a level higher than the preset maximum outlet pressure but lower than the system's ultimate operating pressure. This will allow the outlet air temperature of the indoor heat exchanger to approach the cabin's target temperature as closely as possible.

[0073] In another aspect of the embodiments of this application, a thermal management system is also provided, which includes a compressor, a condenser, an expansion valve and an evaporator, and refrigerant flows inside each component of the thermal management system.

[0074] The compressor plays the role of compressing and driving the refrigerant in the circulation loop. The compressor usually draws the refrigerant from the low-pressure area, compresses it, and sends it to the high-pressure area for cooling and condensation. The heat is released into the air through the compressor's own heat sink, and the compressor discharges high-temperature and high-pressure gaseous refrigerant.

[0075] High-temperature refrigerant passes through the condenser, exchanging heat with the air outside the condenser, thus raising the air temperature. Low-temperature refrigerant passes through the evaporator, exchanging heat with the air outside the evaporator, thus lowering the air temperature.

[0076] The expansion valve uses an electrical signal to control the voltage or current applied to the expansion valve, thereby regulating the refrigerant supply. In this embodiment, the expansion valve is used to control the flow rate of the refrigerant.

[0077] The thermal management system also includes a controller, which controls the thermal management system according to the control method described above. Specifically, the controller runs the control method of the thermal management system and controls the operating status of each component in the thermal management system.

[0078] The thermal management system provided in this application obtains the current control strategy of the system by determining the required heat exchange capacity of the cabin and the preset capacity range in which the required heat exchange capacity is located. This results in different control strategies for the thermal management system in different preset capacity ranges. It can realize zoned control according to different capacity ranges and adjust the control strategy in real time, so that the thermal management system can adapt to energy efficiency control under different operating conditions and achieve maximum energy efficiency.

[0079] In another aspect of this application embodiment, a controller is also provided, which is used to control the thermal management system according to the above-described control method. Specifically, the controller is used to run the control method of the thermal management system and control the operating state of each component in the thermal management system.

[0080] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0081] In the embodiments provided by this invention, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of the units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between devices or units through some interfaces, and may be electrical, mechanical, or other forms.

[0082] The integrated units implemented as software functional units described above can be stored in a computer-readable storage medium. These software functional units, stored in a storage medium, include several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute some steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0083] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A control method of a thermal management system, characterized by, The heat management system comprises an expansion valve, and the method comprises the following steps: determining the current heat exchange capacity of the heat management system; According to the cabin internal demand parameter, the cabin external environment parameter and the cabin operation state parameter, the demand heat exchange capacity Q is acquired c ; comparing the required heat exchange capacity with a plurality of preset capacity reference values to determine the preset capacity interval in which the required heat exchange capacity is located, and obtaining the control strategy of the heat management system, wherein the preset capacity interval is selected from any one of a first preset interval, a second preset interval, a third preset interval and a fourth preset interval, the capacity reference values are Q1, Q2, Q3 and Q4, and Q4>Q3>Q2>Q1; when Qc≤Q1, the required heat exchange capacity is in the fourth preset interval, and the control strategy of the heat management system is a refrigerant dry-wet control strategy; when Q1<Qc≤Q2, the required heat exchange capacity is in the third preset interval, and the control strategy of the heat management system is a refrigerant temperature control strategy; when Q2<Qc≤Q3, the required heat exchange capacity is in the second preset interval, and the control strategy of the heat management system is an optimal working pressure control strategy; when Q3<Qc≤Q4, the required heat exchange capacity is in the first preset interval, and the control strategy of the heat management system is a limit pressure control strategy; and adjusting the opening degree of the expansion valve of the heat management system according to the control strategy, so that the current heat exchange capacity approximates to the required heat exchange capacity.

2. The control method of the thermal management system according to claim 1, characterized by, The heat management system comprises a compressor, a condenser and an evaporator, and the determination of the current heat exchange capacity of the heat management system comprises the following steps: According to the working state of the condenser, the working state of the evaporator and the working state of the compressor, the current heat exchange capacity of the heat management system is obtained.

3. The control method of the thermal management system according to claim 2, characterized by, When the required heat exchange capacity is in the first preset interval, the step of adjusting the opening degree of the expansion valve of the heat management system according to the control strategy comprises the following steps: adjusting the opening degree of the expansion valve so that the outlet pressure of the condenser increases to be higher than a preset maximum outlet pressure and lower than the limit working pressure of the heat management system.

4. The control method of the thermal management system according to claim 2, characterized by, When the required heat exchange capacity is in the second preset interval, the step of adjusting the opening degree of the expansion valve of the heat management system according to the control strategy comprises the following steps: According to the working state of the condenser and the working state of the evaporator, the optimal working pressure of the heat management system is obtained; adjusting the opening degree of the expansion valve so that the outlet pressure of the condenser reaches the optimal working pressure.

5. The control method of the thermal management system according to claim 2, characterized by, When the required heat exchange capacity is in the third preset interval, the step of adjusting the opening degree of the expansion valve of the heat management system according to the control strategy comprises the following steps: According to the outlet temperature of the condenser and the outlet pressure of the condenser, the actual supercooling degree of the condenser is calculated, and the difference between the actual supercooling degree and the target supercooling degree of the heat management system is calculated, and the opening degree of the expansion valve is adjusted according to the difference, so that the actual supercooling degree and the target supercooling degree tend to be equal; or The actual superheat degree of the evaporator is calculated according to the outlet temperature of the evaporator and the inlet pressure of the evaporator, and a difference between the actual superheat degree and a target superheat degree of the thermal management system is calculated, and the opening degree of the expansion valve is adjusted according to the difference, so that the actual superheat degree is equal to the target superheat degree.

6. The control method of the thermal management system according to claim 2, characterized by, When the required heat exchange capacity is in the fourth preset interval, the step of adjusting the opening degree of the expansion valve of the thermal management system according to the control strategy comprises the following steps: The speed of the compressor is controlled to be the lowest speed, and the opening degree of the expansion valve is adjusted to change the dryness of the refrigerant at the outlet of the condenser, so that the actual outlet air temperature of the thermal management system reaches the target temperature of the cabin.

7. A thermal management system comprising a compressor, a condenser, an expansion valve, and an evaporator, the thermal management system thermally managing a cabin; characterized in that, The thermal management system further comprises a controller, and the controller is configured to: determine the current heat exchange capacity of the thermal management system; According to the cabin internal demand parameter, the cabin external environment parameter and the cabin operation state parameter, the demand heat exchange capacity Q is obtained c ; compare the required heat exchange capacity with a plurality of preset capacity reference values to determine a preset capacity interval in which the required heat exchange capacity is located, and obtain a control strategy of the thermal management system, wherein the preset capacity interval is selected from any one of a first preset interval, a second preset interval, a third preset interval and a fourth preset interval, the capacity reference values are Q1, Q2, Q3 and Q4, and Q4>Q3>Q2>Q1; when Qc≤Q1, the required heat exchange capacity is in the fourth preset interval, and the control strategy of the thermal management system is a refrigerant dry-wet control strategy; when Q1<Qc≤Q2, the required heat exchange capacity is in the third preset interval, and the control strategy of the thermal management system is a refrigerant temperature control strategy; when Q2<Qc≤Q3, the required heat exchange capacity is in the second preset interval, and the control strategy of the thermal management system is an optimal working pressure control strategy; when Q3<Qc≤Q4, the required heat exchange capacity is in the first preset interval, and the control strategy of the thermal management system is a limit pressure control strategy; and adjust the opening degree of the expansion valve of the thermal management system according to the control strategy, so that the current heat exchange capacity approximates to the required heat exchange capacity.

8. The system of claim 7, wherein, The controller is further configured to calculate the current heat exchange capacity of the thermal management system according to the working state of the condenser, the working state of the evaporator and the working state of the compressor.

9. The system of claim 7, wherein, The controller is further configured to: when Q3<Qc≤Q4, adjust the opening degree of the expansion valve, so that the outlet pressure of the condenser is increased to be higher than a preset maximum outlet pressure and lower than the limit working pressure of the thermal management system; or, when Q2<Qc≤Q3, obtain the optimal working pressure of the thermal management system according to the working state of the condenser and the working state of the evaporator; adjust the opening degree of the expansion valve, so that the outlet pressure of the condenser reaches the optimal working pressure; or, when Q1<Qc≤Q2, control the speed of the compressor to be the lowest speed, and adjust the opening degree of the expansion valve to change the dryness of the refrigerant at the outlet of the condenser, so that the actual outlet air temperature of the thermal management system reaches the target temperature of the cabin. When Q1 < Qc≤Q2, the actual supercooling degree of the condenser is calculated according to the outlet temperature and the outlet pressure of the condenser; the difference between the actual supercooling degree and the target supercooling degree of the thermal management system is calculated, and the opening of the expansion valve is adjusted according to the difference, so that the actual supercooling degree and the target supercooling degree are equal; or the actual superheating degree of the evaporator is calculated according to the outlet temperature and the outlet pressure of the evaporator, and the difference between the actual superheating degree and the target superheating degree of the thermal management system is calculated, and the opening of the expansion valve is adjusted according to the difference, so that the actual superheating degree and the target superheating degree are equal; Or, When Qc≤Q1, the speed of the compressor is controlled to be the lowest speed, and the opening of the expansion valve is adjusted to change the dryness of the refrigerant at the outlet of the condenser, so that the actual outlet air temperature of the thermal management system reaches the target temperature of the cabin.

10. A controller characterized by comprising: The controller executes the control method of the thermal management system according to any one of claims 1-6.

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