Control method and control device for air conditioning system and air conditioning system

Abstract

The invention relates to the technical field of air conditioning systems, particularly provides a control method and a control device for an air conditioning system and the air conditioning system, and aims to solve the problem that in the defrosting process of an existing air conditioning system, liquid impact of a compressor is avoided by reducing the amount of a refrigerant, but a low-voltage fault occurs in the air conditioning system. The control method for the air conditioning system comprises the steps of controlling a low-pressure pressure sensor to obtain low-pressure pressure Ps of a refrigerant pipeline, comparing the low-pressure pressure Ps of the refrigerant pipeline with preset low-pressure pressure Ps0, controlling an air supply system to be started or stopped based on a comparison result, controlling a temperature sensor to obtain refrigerant temperature T, judging whether the refrigerant temperature T changes or not, and if yes, starting or stopping the air supply system. And controlling the air supply flow of the air supply system based on the judgment result. Therefore, when the low pressure of the refrigerant pipeline is low, the air supplementing system is controlled to be started to supplement air to the refrigerant pipeline, low-pressure faults are avoided, meanwhile, the supplemented refrigerant is made to be in the gas state by judging the temperature of the refrigerant, and liquid impact is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of air-conditioning systems, and specifically provides a control method, a control device and an air-conditioning system for an air-conditioning system. Background Art

[0002] An air-conditioning system usually consists of an indoor unit and an outdoor unit. When the air-conditioning system is working in a low-temperature environment, condensed water is likely to condense into frost on the surface of the condenser, reducing the heat exchange efficiency of the condenser, affecting the cooling or heating effect, increasing energy consumption, and possibly causing equipment damage. Therefore, the air-conditioning system needs to be defrosted when used in a low-temperature environment.

[0003] At present, the outdoor unit of the air-conditioning system is defrosted by powering off the four-way valve for refrigeration operation. In order to improve the user experience and reduce indoor temperature fluctuations, the fan of the indoor unit evaporator is usually not turned on. However, this will cause incomplete evaporation of the refrigerant, and the mixed refrigerant in gaseous and liquid states will enter the compressor, causing liquid hammer in the compressor. In order to reduce compressor liquid hammer, the opening of the electronic expansion valve of the indoor unit is usually closed in the prior art to avoid compressor liquid hammer by reducing the amount of refrigerant. However, reducing the amount of refrigerant can easily cause the system to report a low-pressure fault. Therefore, how to avoid compressor liquid hammer and system low-pressure faults during the defrosting process of the air-conditioning system has become a technical problem that needs to be solved urgently in this field.

[0004] In view of this, the art needs a new control method, control device and air conditioning system for an air conditioning system to solve the existing problems. Summary of the invention

[0005] The present invention aims to solve the above technical problem, that is, to solve the problem that during the defrosting process of the existing air-conditioning system, liquid hammer of the compressor is often avoided by reducing the amount of refrigerant, but low pressure fault occurs in the air-conditioning system.

[0006] In a first aspect, the present invention provides a control method for an air conditioning system, wherein the air conditioning system comprises an outdoor unit, the outdoor unit comprises an air supply system, the air supply system is connected to a refrigerant pipeline of the air conditioning system, a low-pressure pressure sensor for obtaining a low-pressure pressure of the refrigerant pipeline and a temperature sensor for obtaining a refrigerant temperature are arranged on the refrigerant pipeline, the air supply system, the low-pressure pressure sensor and the temperature sensor are all connected to a controller of the air conditioning system in communication, and the control method comprises: controlling the low-pressure pressure sensor to obtain a low-pressure pressure P of the refrigerant pipeline; s , compare the low pressure P of the refrigerant pipeline s With the preset low pressure P s0The size of the air supply system is controlled to start or shut down based on the comparison result, the temperature sensor is controlled to obtain the refrigerant temperature T, and it is determined whether the refrigerant temperature T changes. Based on the determination result, the size of the air supply flow of the air supply system is controlled.

[0007] In the specific implementation of the control method for the air conditioning system, the step of "controlling the air supply system to start or shut down based on the comparison result" further includes: if P s ≤P s0 , then control the air supply system to start.

[0008] In a specific implementation of the above-mentioned control method for an air-conditioning system, a first electronic expansion valve is provided on the refrigerant pipeline, and the first electronic expansion valve is communicatively connected to the controller of the air-conditioning system. The step of "controlling the size of the air supply flow of the air supply system based on the judgment result" further includes: if the refrigerant temperature T decreases, the opening of the first electronic expansion valve is controlled to increase.

[0009] In a specific implementation of the above-mentioned control method for an air-conditioning system, a first electronic expansion valve is provided on the refrigerant pipeline, and the first electronic expansion valve is communicatively connected to the controller of the air-conditioning system, and the step of "controlling the size of the air supply flow of the air supply system based on the judgment result" further includes: if the refrigerant temperature T remains unchanged or increases, the opening of the first electronic expansion valve is controlled to remain unchanged.

[0010] In a specific implementation of the control method for the air conditioning system, the air conditioning system further includes an indoor unit, the indoor unit includes a second electronic expansion valve, the second electronic expansion valve is communicatively connected to the controller of the air conditioning system, and the step "if the refrigerant temperature T remains unchanged or increases, then the opening of the first electronic expansion valve is controlled to remain unchanged" further includes: comparing the low pressure P of the refrigerant pipeline s With the preset low pressure P s0 The size of P s ≤P s0 , then obtain the state of the indoor unit before defrosting; and control the opening of the second electronic expansion valve based on the state of the indoor unit before defrosting.

[0011] In the specific implementation of the above-mentioned control method for the air-conditioning system, the step of "controlling the opening of the second electronic expansion valve based on the state of the indoor unit before defrosting" further includes: if the indoor unit is in the startup state before defrosting, the opening of the second electronic expansion valve is controlled to remain unchanged.

[0012] In the specific implementation of the above-mentioned control method for the air-conditioning system, the step of "controlling the opening of the second electronic expansion valve based on the state of the indoor unit before defrosting" also includes: if the indoor unit is in a closed state before defrosting, the opening of the second electronic expansion valve is controlled to increase.

[0013] In a second aspect, the present invention further provides a control device for an air-conditioning system, comprising a processor and a memory storing program instructions, wherein the processor is configured to execute the control method for an air-conditioning system described in any one of the above-mentioned embodiments when running the program instructions.

[0014] The present invention also provides an air-conditioning system, which includes an outdoor unit and an indoor unit, wherein the outdoor unit includes a compressor, a four-way valve, a first outdoor heat exchanger, a second outdoor heat exchanger, an economizer, a gas-liquid separator and an air supply system, wherein the exhaust port of the compressor is connected to the first outdoor heat exchanger and the second outdoor heat exchanger respectively after passing through the four-way valve, the first outdoor heat exchanger and the second outdoor heat exchanger are connected to the economizer, the economizer is connected to a first branch and a second branch, the first branch is connected to the indoor unit, the four-way valve, the gas-liquid separator and the first air inlet of the compressor in sequence, the second branch is provided with a first electronic expansion valve and a temperature sensor, the air supply system is connected to the second branch through the first electronic expansion valve, the second branch includes a first sub-branch, the first sub-branch is connected to the gas-liquid separator and the first air inlet of the compressor in sequence, and the first sub-branch is provided with a first solenoid valve and a low-pressure pressure sensor.

[0015] In a specific embodiment of the above air-conditioning system, the second branch further includes a second sub-branch, the second sub-branch is connected to the second air inlet of the compressor, and a second solenoid valve is provided on the second sub-branch.

[0016] The technical effect of the present invention is that since the air conditioning system of the present invention is provided with an air supply system, a low-pressure pressure sensor and a temperature sensor, during the defrosting process of the air conditioning system, the low-pressure pressure P of the refrigerant pipeline is obtained through the low-pressure pressure sensor. s Then compare the low pressure of the refrigerant in the refrigerant pipeline with the preset low pressure P s0 When P s ≤P s0, it means that the low pressure of the refrigerant in the pipeline is too small, and a low pressure fault is prone to occur. Therefore, the air replenishment system is controlled to start to replenish the refrigerant pipeline, thereby avoiding the problem of low pressure fault in the air conditioning system. On the other hand, during the defrosting process, the temperature of the refrigerant in the condenser continues to decrease after heat exchange with frost or ice. In order to avoid incomplete evaporation of the evaporator, the present invention can also obtain the refrigerant temperature T. The temperature of the refrigerant in the pipeline gradually increases during the air replenishment process. During the defrosting process, the air replenishment flow rate of the air replenishment system can be controlled to delay and eventually avoid the continuous decrease of the refrigerant temperature in the pipeline, so that the replenished refrigerant reaches the evaporation saturation temperature, thereby ensuring that the replenished refrigerant is gaseous refrigerant, avoiding the problem of liquid hammer in the compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which:

[0018] Figure 1 is a main flow chart of a control method for an air conditioning system in Embodiment 1 of the present invention;

[0019] Figure 2 is a flow chart of step S3 of the control method for an air conditioning system in the first embodiment of the present invention;

[0020] Figure 3 is a flow chart of step S6 of the control method for an air conditioning system in the first embodiment of the present invention;

[0021] Figure 4 is a main flow chart of a control method for an air conditioning system in Embodiment 2 of the present invention;

[0022] Figure 5 is a flow chart of step S64 of the control method for an air conditioning system in the second embodiment of the present invention;

[0023] Figure 6 It is a structural schematic diagram of the air conditioning system of the present invention.

[0024] List of reference numerals:

[0025] 1. Air conditioning system; 11. Indoor unit; 12. Outdoor unit; 121. Compressor; 122. Four-way valve; 123. First outdoor heat exchanger; 124. Second outdoor heat exchanger; 125. Economizer; 126. First branch; 127. Second branch; 1271. First electronic expansion valve; 1272. Temperature sensor; 1273. First sub-branch; 1274. Second sub-branch; 1275. First solenoid valve; 1276. Low-pressure pressure sensor; 1277. Second solenoid valve; 128. Gas-liquid separator. DETAILED DESCRIPTION

[0026] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0027] It should be noted that in the description of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0028] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] First, the existing air-conditioning system is described. At present, the outdoor unit of the air-conditioning system is defrosted by powering off the four-way valve for refrigeration operation. In order to improve the user experience and reduce indoor temperature fluctuations, the fan of the indoor unit evaporator is usually not turned on. However, this will cause incomplete evaporation of the refrigerant, and a mixture of gaseous and liquid refrigerants will enter the compressor, causing liquid hammer in the compressor. In order to reduce compressor liquid hammer, the prior art usually closes the opening of the indoor unit's electronic expansion valve to reduce the amount of refrigerant to avoid compressor liquid hammer. However, reducing the amount of refrigerant can easily cause the system to report a low-pressure fault. Therefore, how to avoid compressor liquid hammer and system low-pressure faults during the defrosting process of the air-conditioning system has become a technical problem that needs to be solved urgently in this field. To this end, the following implementation methods are proposed.

[0030] Embodiment 1

[0031] like Figure 1-Figure 3As shown, in order to solve the problem that the existing air-conditioning system often reduces the amount of refrigerant to avoid liquid hammer in the compressor during the defrosting process, but causes a low-pressure fault in the air-conditioning system, the air-conditioning system of the present invention includes an outdoor unit, the outdoor unit includes an air supply system, the air supply system is connected to the refrigerant pipeline of the air-conditioning system, a low-pressure pressure sensor for obtaining the low-pressure pressure of the refrigerant pipeline and a temperature sensor for obtaining the refrigerant temperature are provided on the refrigerant pipeline, the air supply system, the low-pressure pressure sensor and the temperature sensor are all connected to the controller of the air-conditioning system, a first electronic expansion valve is provided on the refrigerant pipeline, and the first electronic expansion valve is connected to the controller of the air-conditioning system, and the control method includes:

[0032] S1, control the low pressure sensor to obtain the low pressure P of the refrigerant pipeline s ;

[0033] S2, compare the low pressure P of the refrigerant pipeline s With the preset low pressure P s0 size;

[0034] S3, controlling the air supply system to start or shut down based on the comparison result;

[0035] S4, controlling the temperature sensor to obtain the refrigerant temperature T;

[0036] S5, judging whether the refrigerant temperature T changes;

[0037] S6. Control the size of the air supply flow rate of the air supply system based on the judgment result.

[0038] In the above steps, step S3 further comprises:

[0039] S31, if P s ≤P s0 , then the control air supply system starts.

[0040] Step S6 further comprises:

[0041] S61, if the refrigerant temperature T decreases, the opening of the first electronic expansion valve is controlled to increase;

[0042] S62: If the refrigerant temperature T remains unchanged or increases, the opening of the first electronic expansion valve is controlled to remain unchanged.

[0043] In the case of adopting the above embodiment, in order to avoid the low pressure of the refrigerant in the system causing a low pressure fault in the system, the low pressure sensor is first controlled in the embodiment to obtain the low pressure P of the refrigerant in the refrigerant pipeline. s , and then compare the low pressure P of the refrigerant s With the preset low pressure P s0 If P s ≤Ps0 , indicating that the low pressure of the refrigerant in the refrigerant pipeline is too low at this time, and there is a risk of low pressure failure. Therefore, the air replenishment system is controlled to start replenishing air (supplementing refrigerant) in the refrigerant pipeline. As the low pressure of the refrigerant in the refrigerant pipeline P s The gradually increase of the pressure, the risk of low-pressure failure in the system is reduced until the safe low-pressure pressure value is reached. On the other hand, in the process of replenishing refrigerant into the refrigerant pipeline, the air replenishment system will not only increase the low pressure of the refrigerant, but also gradually increase the temperature of the refrigerant in the pipeline. Therefore, a temperature sensor for obtaining the temperature of the refrigerant is also provided in the present embodiment. In the process of the air replenishment system filling the refrigerant pipeline with air, the temperature sensor is controlled to obtain the refrigerant temperature T at the same time, and it is determined whether the refrigerant temperature T changes, and then the air replenishment flow of the air replenishment system is adjusted according to the change of the refrigerant temperature. Specifically, due to the heat exchange between the refrigerant in the condenser and the frost outside the condenser during the defrosting process, the temperature of the refrigerant gradually decreases. Therefore, in the process of filling the refrigerant pipeline with air, the heat obtained by the refrigerant does not actually directly increase the temperature of the refrigerant, but needs to first make up for the heat lost when the refrigerant exchanges heat with the frost. When the heat obtained by the refrigerant is equal to the heat lost by the heat exchange, the temperature of the refrigerant will not continue to decrease. Therefore, in the process of the air replenishment system filling the refrigerant pipeline with air, the temperature of the refrigerant may be reduced, unchanged or increased. If the refrigerant temperature T is in a decreasing state, it means that the air supply flow of the air supply system is relatively small at this time, so the opening of the first electronic expansion valve is controlled to increase to increase the flow of the refrigerant, thereby increasing the heating rate of the refrigerant in the pipeline, so that the refrigerant in the pipeline can reach the evaporation saturation temperature as soon as possible. If the refrigerant temperature T remains unchanged or increases, it means that the refrigerant in the pipeline has reached the evaporation saturation temperature. At this time, the refrigerant in the pipeline is in a gaseous state, thereby avoiding the liquid refrigerant entering the compressor and causing the compressor to have a liquid hammer phenomenon. Therefore, at this time, the opening of the first electronic expansion valve can be controlled to remain unchanged.

[0044] In summary, the control method for an air-conditioning system of the present invention solves the problem that during the defrosting process of the existing air-conditioning system, liquid hammer of the compressor is often avoided by reducing the amount of refrigerant, but low-pressure fault occurs in the air-conditioning system.

[0045] Embodiment 2

[0046] The above-mentioned embodiment 1 proposes a solution that can avoid liquid hammer in the compressor and low-pressure failure in the system, thereby ensuring stable defrosting of the air-conditioning system. Since defrosting is equivalent to cooling mode, although the fan of the indoor unit is turned off in defrosting mode, the heat exchanger of the indoor unit will absorb indoor heat during the defrosting process, reducing the user experience. Therefore, in this embodiment, if Figure 4 , Figure 5 As shown, after step S62, the following steps are also included:

[0047] S2, compare the low pressure P of the refrigerant pipeline s With the preset low pressure P s0 size;

[0048] S63, if P s ≤P s0 , then obtain the state of the indoor unit before defrosting;

[0049] S64: Control the opening degree of the second electronic expansion valve based on the state of the indoor unit before defrosting.

[0050] In the above steps, step S64 further includes:

[0051] S641, if the indoor unit is in the start-up state before defrosting, the opening degree of the second electronic expansion valve is controlled to remain unchanged;

[0052] S642: If the indoor unit is in the closed state before defrosting, the opening of the second electronic expansion valve is controlled to increase.

[0053] In the case of the above embodiment, firstly, the low pressure P of the refrigerant pipeline is compared. s With the preset low pressure P s0 If the size of P s ≤P s0 , indicating that the low pressure is too low at this time. At this time, the state of the indoor unit before defrosting is obtained. If the indoor unit is in the starting state before defrosting, it means that there may be someone in the room before defrosting. At this time, the indoor temperature should not fluctuate greatly. Therefore, the opening of the second electronic expansion valve is controlled to remain unchanged, so that the indoor environment is not significantly affected and the compressor frequency is not reduced. If the indoor unit is in the closed state before defrosting, it means that there should be no one in the room before defrosting, and it is unlikely that there is someone in the room during the defrosting process. Therefore, the opening of the second electronic expansion valve is controlled to increase, increase the refrigerant flow of the indoor unit, and allow the evaporator to fully absorb the indoor heat to evaporate the refrigerant, effectively speeding up the defrosting speed.

[0054] In addition, the present invention also provides a control device for an air-conditioning system, including a processor and a memory storing program instructions, wherein the processor is configured to execute a control method for an air-conditioning system as described in any one of the above-mentioned embodiments when running the program instructions.

[0055] Embodiment 3

[0056] like Figure 6As shown, the present invention also provides an air conditioning system 1, the air conditioning system 1 includes an outdoor unit 12 and an indoor unit 11, the outdoor unit 12 includes a compressor 121, a four-way valve 122, a first outdoor heat exchanger 123, a second outdoor heat exchanger 124, an economizer 125, a gas-liquid separator 128 and an air supply system, wherein the exhaust port of the compressor 121 is respectively connected to the first outdoor heat exchanger 123 and the second outdoor heat exchanger 124 after passing through the four-way valve 122, the first outdoor heat exchanger 123 and the second outdoor heat exchanger 124 are connected to the economizer 125, and the economizer 125 is connected to the first branch 126 and the second branch 128. 127, the first branch 126 is connected to the indoor unit 11, the four-way valve 122, the gas-liquid separator 128 and the first air inlet of the compressor 121 in sequence, the second branch 127 is provided with a first electronic expansion valve 1271 and a temperature sensor 1272, the air supply system is connected to the second branch 127 through the first electronic expansion valve 1271, the second branch 127 includes a first sub-branch 1273, the first sub-branch 1273 is connected to the gas-liquid separator 128 and the first air inlet of the compressor 121 in sequence, the first sub-branch 1273 is provided with a first electromagnetic valve 1275 and a low-pressure pressure sensor 1276. The second branch 127 also includes a second sub-branch 1274, the second sub-branch 1274 is connected to the second air inlet of the compressor 121, and the second sub-branch 1274 is provided with a second electromagnetic valve 1277.

[0057] In the case of adopting the above embodiment, during the defrosting process of the air conditioning system 1 of the present invention, the refrigerant enters the first outdoor heat exchanger 123 and the second outdoor heat exchanger 124 respectively after passing through the d port and the c port of the four-way valve 122 from the exhaust port of the compressor 121, and then passes through the third electronic expansion valve. A part of the refrigerant flows through the economizer 125 and the second electronic expansion valve of the indoor unit 11 along the first branch 126, and enters the gas-liquid separator 128 from the e port and the s port of the four-way valve 122, and finally enters the compressor 121 from the first air inlet of the compressor 121. Another part of the refrigerant passes through the first electronic expansion valve 1271 and the economizer 125 along the second branch 127, and a part of it passes through the first electromagnetic valve 1275 along the first sub-branch 1273 and enters the gas-liquid separator 128, and finally enters the compressor 121 from the first air inlet of the compressor 121, and another part of it passes through the second electromagnetic valve 1277 along the second sub-branch 1274 and enters the compressor 121 from the second air inlet of the compressor 121. Therefore, when the temperature of the refrigerant added into the pipeline has not reached the evaporation saturation temperature, the first electronic expansion valve 1271 and the first solenoid valve 1275 are opened to allow the refrigerant to pass through the gas-liquid separator 128 and then enter the compressor 121. When the temperature of the refrigerant added into the pipeline reaches the evaporation saturation temperature, the first electronic expansion valve 1271, the first solenoid valve 1275 and the second solenoid valve 1277 can be opened at the same time to increase the gas replenishment rate.

[0058] It should be noted that the above-mentioned implementation mode is only used to illustrate the principle of the present invention and is not intended to limit the scope of protection of the present invention. Without departing from the principle of the present invention, those skilled in the art can adjust the above-mentioned structure so that the present invention can be applied to more specific application scenarios.

[0059] Those skilled in the art can understand that the above-mentioned air conditioning system also includes some other well-known structures, such as processors, controllers, memories, etc., wherein the memories include but are not limited to random access memory, flash memory, read-only memory, programmable read-only memory, volatile memory, non-volatile memory, serial memory, parallel memory or registers, etc., and the processor includes but is not limited to CPLD / FPGA, DSP, ARM processor, MIPS processor, etc. In order to unnecessarily obscure the embodiments of the present disclosure, these well-known structures are not shown in the drawings.

[0060] Although the various steps in the above embodiment are described in the above order, those skilled in the art will understand that in order to achieve the effect of this embodiment, different steps do not have to be executed in such an order, and they can be executed simultaneously (in parallel) or in a reverse order, such as step S1 and step S4. These simple changes are within the scope of protection of the present invention.

[0061] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A control method for an air conditioning system (1), characterized in that: The air conditioning system (1) comprises an outdoor unit (12), the outdoor unit (12) comprises an air supply system, the air supply system is connected to a refrigerant pipeline of the air conditioning system (1), a low pressure sensor (1276) for obtaining the low pressure of the refrigerant pipeline and a temperature sensor (1272) for obtaining the refrigerant temperature are arranged on the refrigerant pipeline, the air supply system, the low pressure sensor (1276) and the temperature sensor (1272) are all connected to a controller of the air conditioning system (1) for communication, and the control method comprises: Controlling the low pressure sensor (1276) to obtain the low pressure Ps of the refrigerant pipeline; Comparing the low pressure Ps of the refrigerant pipeline with the preset low pressure Ps0; Based on the comparison result, the air supply system is controlled to start or shut down; Controlling the temperature sensor (1272) to obtain the refrigerant temperature T; Determining whether the refrigerant temperature T changes; The size of the air supply flow rate of the air supply system is controlled based on the judgment result.

2. The control method for an air conditioning system (1) according to claim 1, characterized in that: The step of "controlling the air supply system to start or shut down based on the comparison result" further includes: If Ps≤Ps0, the air supply system is controlled to start.

3. The control method for an air conditioning system (1) according to claim 2, characterized in that: The refrigerant pipeline is provided with a first electronic expansion valve (1271), the first electronic expansion valve (1271) is communicatively connected to the controller of the air conditioning system (1), and the step of "controlling the size of the air supply flow of the air supply system based on the judgment result" further comprises: If the refrigerant temperature T decreases, the opening of the first electronic expansion valve (1271) is controlled to increase.

4. The control method for an air conditioning system (1) according to claim 2, characterized in that: The refrigerant pipeline is provided with a first electronic expansion valve (1271), the first electronic expansion valve (1271) is communicatively connected to the controller of the air conditioning system (1), and the step of "controlling the size of the air supply flow of the air supply system based on the judgment result" further comprises: If the refrigerant temperature T remains unchanged or increases, the opening of the first electronic expansion valve (1271) is controlled to remain unchanged.

5. The control method for an air conditioning system (1) according to claim 4, characterized in that: The air conditioning system (1) further comprises an indoor unit (11), the indoor unit (11) comprising a second electronic expansion valve, the second electronic expansion valve being communicatively connected to a controller of the air conditioning system (1), and the step "if the refrigerant temperature T remains unchanged or increases, then controlling the opening of the first electronic expansion valve (1271) to remain unchanged" further comprises: Comparing the low pressure Ps of the refrigerant pipeline with the preset low pressure Ps0; If Ps≤Ps0, the state of the indoor unit (11) before defrosting is obtained; The opening degree of the second electronic expansion valve is controlled based on the state of the indoor unit (11) before defrosting.

6. The control method for an air conditioning system (1) according to claim 5, characterized in that: The step of "controlling the opening of the second electronic expansion valve based on the state of the indoor unit (11) before defrosting" further includes: If the indoor unit (11) is in a startup state before defrosting, the opening degree of the second electronic expansion valve is controlled to remain unchanged.

7. The control method for an air conditioning system (1) according to claim 5, characterized in that: The step of "controlling the opening of the second electronic expansion valve based on the state of the indoor unit (11) before defrosting" also includes: If the indoor unit (11) is in a closed state before defrosting, the opening degree of the second electronic expansion valve is controlled to increase.

8. A control device for an air conditioning system (1), comprising a processor and a memory storing program instructions, characterized in that: The processor is configured to execute the control method for the air conditioning system (1) according to any one of claims 1 to 7 when running the program instructions.

9. An air conditioning system (1), characterized in that: The air conditioning system (1) comprises an outdoor unit (12) and an indoor unit (11); the outdoor unit (12) comprises a compressor (121), a four-way valve (122), a first outdoor heat exchanger (123), a second outdoor heat exchanger (124), an economizer (125), a gas-liquid separator (128) and an air supply system; wherein the exhaust port of the compressor (121) is respectively connected to the first outdoor heat exchanger (123) and the second outdoor heat exchanger (124) after passing through the four-way valve (122); the first outdoor heat exchanger (123) and the second outdoor heat exchanger (124) are connected to the economizer (125); the economizer (125) is connected to a first branch (126) and a second branch (127); the first branch (126) and the second branch (127) are connected to the economizer (125); The second branch (126) is connected in sequence to the indoor unit (11), the four-way valve (122), the gas-liquid separator (128) and the first air inlet of the compressor (121); the second branch (127) is provided with a first electronic expansion valve (1271) and a temperature sensor (1272); the air supply system is connected to the second branch (127) through the first electronic expansion valve (1271); the second branch (127) includes a first sub-branch (1273); the first sub-branch (1273) is connected in sequence to the gas-liquid separator (128) and the first air inlet of the compressor (121); the first sub-branch (1273) is provided with a first solenoid valve (1275) and a low-pressure pressure sensor (1276).

10. The air conditioning system (1) according to claim 9, characterized in that: The second branch (127) further comprises a second sub-branch (1274), wherein the second sub-branch (1274) is in communication with a second air inlet of the compressor (121), and a second solenoid valve (1277) is provided on the second sub-branch (1274).

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