Compressor liquid return control method and compressor liquid return control system

Abstract

The invention discloses a compressor liquid return control method and a compressor liquid return control system. The compressor liquid return control method is applied to the air conditioning unit, the air conditioning unit comprises a compressor and a fan, and the compressor liquid return control method comprises the steps that the operation frequency of the compressor, the fan rotating speed of the fan and the operation high-pressure pressure and the operation low-pressure pressure of the air conditioning unit are obtained in a preset period; judging whether the compressor has a liquid return phenomenon or not according to the operation frequency, the fan rotating speed, the operation high-pressure pressure and the operation low-pressure pressure; and when the liquid return phenomenon exists in the compressor, the compressor is protected and controlled. Therefore, no other modules need to be additionally arranged, whether the liquid return phenomenon exists in the compressor or not can be accurately judged, cost is low, in addition, the compressor can be protected and controlled, damage to the compressor caused by liquid return is effectively reduced, and the reliability of the air conditioning unit is improved.

Description

Technical Field

[0001] The present application relates to the technical field of air conditioning, and in particular to a compressor liquid return control method and a compressor liquid return control system. Background Art

[0002] Due to many factors affecting the operating status, system control, and on-site installation of air-conditioning units, liquid backflow often occurs in the compressor of air-conditioning units. As the core component of the air-conditioning unit, the compressor will fail due to liquid backflow, which will directly affect the reliable operation of the air-conditioning unit. Therefore, how to accurately determine whether there is liquid backflow in the compressor is an urgent problem to be solved. Summary of the invention

[0003] The embodiments of the present application provide a compressor liquid return control method, a control device, a control system and a computer-readable storage medium to solve at least one of the above-mentioned technical problems.

[0004] The compressor liquid return control method of the embodiment of the present application is applied to an air conditioning unit, wherein the air conditioning unit includes a compressor and a fan, and the compressor liquid return control method includes:

[0005] Acquiring the operating frequency of the compressor, the fan speed of the fan, and the operating high pressure and the operating low pressure of the air conditioning unit at a preset period;

[0006] Determining whether the compressor has liquid backflow according to the operating frequency, the fan speed, the operating high pressure, and the operating low pressure;

[0007] When liquid backflow occurs in the compressor, protection control is performed on the compressor.

[0008] In some embodiments, the fan includes an outdoor fan and an indoor fan, and obtaining the fan speed of the fan in a preset period includes:

[0009] When the air-conditioning unit operates in a cooling mode, obtaining a first fan speed of the outdoor fan in the preset cycle as the fan speed;

[0010] When the air-conditioning unit operates in a heating mode, a second fan speed of the indoor fan is obtained in the preset cycle as the fan speed.

[0011] In some embodiments, the air conditioning unit includes a first pressure sensor and a second pressure sensor, wherein the first pressure sensor is disposed at the exhaust end of the compressor, and the second pressure sensor is disposed at the suction end of the compressor, and the operating high pressure and the operating low pressure of the air conditioning unit are obtained in a preset cycle, including:

[0012] obtaining the operating high pressure of the air conditioning unit at the preset period through the first pressure sensor;

[0013] The operating low pressure of the air-conditioning unit is obtained at the preset period through the second pressure sensor.

[0014] In some embodiments, judging whether the compressor has liquid backflow according to the operating frequency, the fan speed, the operating high pressure, and the operating low pressure includes:

[0015] Calculate the difference between the operating frequency obtained at the current moment and the operating frequency obtained at the previous moment to obtain a frequency difference;

[0016] Calculate the difference between the fan speed obtained at the current moment and the fan speed obtained at the previous moment to obtain a speed difference;

[0017] Calculating the difference between the operating high pressure pressure obtained at the current moment and the operating high pressure pressure obtained at the previous moment to obtain a high pressure pressure difference;

[0018] Calculating the difference between the operating low pressure obtained at the current moment and the operating low pressure obtained at the previous moment to obtain a low pressure difference;

[0019] It is determined whether liquid backflow occurs in the compressor according to the frequency difference, the speed difference, the high-pressure difference and the low-pressure difference.

[0020] In some embodiments, judging whether the compressor has liquid backflow according to the frequency difference, the speed difference, the high pressure difference and the low pressure difference includes:

[0021] When, in a predetermined number of consecutive preset cycles, the frequency difference is zero, the speed difference is less than the preset speed difference, the high-pressure difference is greater than or equal to the first pressure difference, and the low-pressure difference is greater than or equal to the second pressure difference, it is determined that the compressor has liquid backflow;

[0022] When the frequency difference is not zero, and / or the speed difference is greater than or equal to the preset speed difference, and / or the high-pressure pressure difference is less than the first pressure difference, and / or the low-pressure pressure difference is less than the second pressure difference, it is determined that there is no liquid return phenomenon in the compressor.

[0023] In some embodiments, the air conditioning unit further includes an expansion valve, the expansion valve is connected to the fan, and when the compressor has liquid backflow, the compressor is protected and controlled, including:

[0024] When liquid backflow occurs in the compressor, the compressor is protected and controlled by correcting and controlling the opening of the expansion valve, the superheat of the compressor and the operating frequency.

[0025] In certain embodiments, when the compressor has liquid backflow, the compressor is protected and controlled by correcting and controlling the opening of the expansion valve, the superheat of the compressor and the operating frequency, including:

[0026] When the compressor has liquid backflow, the opening of the expansion valve is reduced to increase the exhaust superheat and suction superheat of the compressor, and the step of obtaining the operating frequency of the compressor, the fan speed of the fan, and the operating high pressure and the operating low pressure of the air conditioning unit in a preset cycle is returned to determine again whether the compressor has liquid backflow;

[0027] When it is determined again that the compressor has a liquid backflow phenomenon, determining whether the opening of the expansion valve is equal to a preset opening;

[0028] When the opening of the expansion valve is not equal to the preset opening, returning to the step of reducing the opening of the expansion valve to increase the exhaust superheat and suction superheat of the compressor;

[0029] When the opening degree of the expansion valve is equal to the preset opening degree, reducing the operating frequency;

[0030] Whether it is necessary to start unit protection is determined based on the reduced operating frequency.

[0031] In some embodiments, after determining again whether the compressor has liquid backflow, the compressor liquid backflow control method further includes:

[0032] When there is no liquid return phenomenon in the compressor, the compressor is controlled to operate while maintaining the exhaust gas superheat and the suction gas superheat at the current moment.

[0033] In some embodiments, judging whether it is necessary to start unit protection according to the reduced operating frequency includes:

[0034] Determining whether the reduced operating frequency is equal to a frequency threshold;

[0035] When the reduced operating frequency is less than or equal to the frequency threshold, maintaining the frequency threshold operation and starting unit protection;

[0036] When the reduced operating frequency is greater than the frequency threshold, returning to the step of obtaining the operating frequency of the compressor, the fan speed of the fan, and the operating high pressure and the operating low pressure of the air-conditioning unit at a preset period, to again determine whether there is liquid backflow in the compressor;

[0037] When it is determined again that the compressor has liquid backflow, returning to the step of reducing the operating frequency;

[0038] When there is no liquid return phenomenon in the compressor, the compressor is controlled to maintain the operating frequency, the exhaust superheat and the suction superheat at the current moment.

[0039] The compressor liquid return control device of the embodiment of the present application is applied to an air conditioning unit, wherein the air conditioning unit includes a compressor and a fan, and the compressor liquid return control device includes:

[0040] An acquisition module, used for acquiring the operating frequency of the compressor, the fan speed of the fan, and the operating high pressure and the operating low pressure of the air-conditioning unit at a preset period;

[0041] A judging module, used for judging whether the compressor has liquid backflow phenomenon according to the operating frequency, the fan speed, the operating high pressure and the operating low pressure;

[0042] The control module is used to perform protection control on the compressor when liquid backflow occurs in the compressor.

[0043] The compressor liquid return control system of the embodiment of the present application includes one or more processors and a memory, and the memory stores a computer program. When the computer program is executed by the processor, the compressor liquid return control method of any of the above embodiments is implemented.

[0044] The computer-readable storage medium of the embodiment of the present application stores a computer program thereon, and when the program is executed by a processor, the compressor liquid return control method of any of the above-mentioned embodiments is implemented.

[0045] In the compressor liquid return control method, control device, control system and computer-readable storage medium of the embodiment of the present application, the operating frequency of the compressor, the fan speed of the fan, and the operating high pressure and operating low pressure of the air-conditioning unit are obtained in a preset cycle, and the compressor is judged whether there is liquid return according to the operating frequency, fan speed, operating high pressure and operating low pressure, and a joint judgment is made by combining multiple parameters, and the compressor is protected and controlled when there is liquid return. In this way, it is possible to accurately judge whether there is liquid return in the compressor without adding other modules, and the cost is low. In addition, the compressor can be protected and controlled, effectively reducing the damage to the compressor caused by liquid return and improving the reliability of the air-conditioning unit.

[0046] Additional aspects and advantages of the embodiments of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0048] Figure 1 is a flow chart of a compressor liquid return control method according to certain embodiments of the present application;

[0049] Figure 2 is a schematic diagram of the structure of an air conditioning unit according to some embodiments of the present application;

[0050] Figure 3 is a flow chart of a compressor liquid return control method according to certain embodiments of the present application;

[0051] Figure 4 is a flow chart of a compressor liquid return control method according to certain embodiments of the present application;

[0052] Figure 5 is a flow chart of a compressor liquid return control method according to certain embodiments of the present application;

[0053] Figure 6 is a flow chart of a compressor liquid return control method according to certain embodiments of the present application;

[0054] Figure 7 is a flow chart of a compressor liquid return control method according to certain embodiments of the present application;

[0055] Figure 8 It is a schematic diagram of a flow chart of protection control of an air conditioning unit in certain implementation modes of the present application;

[0056] Fig. 9is a flow chart of a compressor liquid return control method according to certain embodiments of the present application;

[0057] Fig.10 is a flow chart of a compressor liquid return control method according to certain embodiments of the present application;

[0058] Fig.11 is a flow chart of a compressor liquid return control method according to certain embodiments of the present application;

[0059] Fig.12 is a module schematic diagram of a compressor liquid return control device according to certain embodiments of the present application;

[0060] Fig.13 is a module schematic diagram of a compressor liquid return control system according to certain embodiments of the present application;

[0061] Fig.14 It is a schematic diagram of the connection status between a computer-readable storage medium and a processor in certain embodiments of the present application.

[0062] Description of reference numerals:

[0063] Air conditioning unit 100, compressor 10, fan 20, outdoor fan 21, indoor fan 22, first pressure sensor 31, second pressure sensor 32, expansion valve 40, first expansion valve 41, second expansion valve 42, four-way valve 50, outdoor heat exchanger 61, indoor heat exchanger 62, gas-liquid separator 70, compressor liquid return control device 200, acquisition module 210, judgment module 220, control module 230, compressor liquid return control system 300, processor 310, memory 320, computer readable storage medium 400, computer program 410, processor 420. DETAILED DESCRIPTION

[0064] The following is a further description of the embodiments of the present application in conjunction with the accompanying drawings. The same or similar reference numerals in the accompanying drawings represent the same or similar elements or elements with the same or similar functions from beginning to end. In addition, the embodiments of the present application described below in conjunction with the accompanying drawings are exemplary and are only used to explain the embodiments of the present application, and cannot be understood as limiting the present application.

[0065] See also Figure 1 and Figure 2 The embodiment of the present application provides a compressor 10 liquid return control method, which is applied to an air conditioning unit 100. The air conditioning unit 100 includes a compressor 10 and a fan 20. The compressor 10 liquid return control method includes:

[0066] 010: Obtaining the operating frequency of the compressor 10, the fan speed of the fan 20, and the operating high pressure and the operating low pressure of the air conditioning unit 100 at a preset period;

[0067] 020: Determine whether there is liquid backflow in the compressor 10 according to the operating frequency, fan speed, operating high pressure and operating low pressure;

[0068] 030: When liquid backflow occurs in the compressor 10, protection control is performed on the compressor 10.

[0069] In the compressor 10 liquid return control method of the embodiment of the present application, the operating frequency of the compressor 10, the fan speed of the fan 20, and the operating high pressure and operating low pressure of the air conditioning unit 100 are obtained in a preset cycle to determine whether the compressor 10 has a liquid return phenomenon, and a joint judgment is made based on a combination of multiple parameters. When the compressor 10 has a liquid return phenomenon, the compressor 10 is protected and controlled. In this way, it is possible to accurately determine whether the compressor 10 has a liquid return phenomenon without adding other modules, and the cost is low. In addition, the compressor 10 can also be protected and controlled, effectively reducing the damage to the compressor 10 caused by the liquid return, and improving the reliability of the air conditioning unit 100.

[0070] Specifically, the air conditioning unit 100 includes a compressor 10 and a fan 20. The compressor 10 is used to absorb low-temperature and low-pressure refrigerant, convert it into high-temperature and high-pressure refrigerant for discharge. In the embodiment of the present application, the compressor 10 is a rolling rotor compressor. The fan 20 is used to realize air circulation and transfer between the air conditioning unit 100 and the external environment.

[0071] The operating frequency of the compressor 10, the fan speed of the fan 20, and the operating high pressure and operating low pressure of the air-conditioning unit 100 are obtained in a preset cycle. The preset cycle can be set to 5-10 minutes, and can be set differently according to actual conditions. For example, the preset cycle can be set to 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, or any number of minutes within 5-10 minutes. The operating frequency of the compressor 10 can be read directly from the compressor 10, and the fan speed of the fan 20 can be read directly from the fan 20. The operating high pressure of the air-conditioning unit 100 is the pressure at the exhaust end of the compressor 10, and the operating low pressure is the pressure at the suction end of the compressor 10. Both the operating high pressure and the operating low pressure can be obtained through the pressure sensor configured by the air-conditioning unit 100 itself.

[0072] It should be noted that the rolling rotor compressor does not have an air intake valve at the air intake end, and relies on the intake air to directly perform cyclic compression (the low-pressure area and the high-pressure area are isolated by the sliding vane inside the compression chamber). Therefore, once there is a small amount of liquid return or there is liquid in the oil pump system, it cannot be compressed, and the pressure in the compression chamber increases sharply. The high-pressure area of ​​the rotary compressor isolated by the valve plate has an internal pressure relief design. The timing of the compressor 10 stopping compression will change with the change of pressure in the exhaust pipe. Intermittent liquid return or a small amount of liquid return will also cause pressure changes. Therefore, the periodic fluctuations of the operating high pressure and the operating low pressure of the air-conditioning unit 100 can be used as one of the bases for judging whether the compressor 10 has liquid return.

[0073] As can be seen from the above, it can be determined whether the compressor 10 has liquid backflow according to the change of the operating frequency, the change of the fan speed, the fluctuation of the operating high pressure and the operating low pressure. When it is determined that the compressor 10 has liquid backflow, the compressor 10 is protected and controlled to reduce the damage to the compressor 10 caused by the liquid backflow.

[0074] In the related art, in order to prevent liquid backflow from the compressor 10, when the air conditioner is running, the exhaust superheat and the suction superheat of the compressor 10 are controlled within a certain range to reduce the probability of liquid backflow from the compressor 10. However, this method cannot prevent liquid backflow from the compressor 10, and it is impossible to accurately determine whether there is liquid backflow from the compressor 10.

[0075] In other related technologies, it is determined whether the compressor 10 has liquid backflow according to the operating power, operating frequency and outdoor ambient temperature of the compressor 10. However, due to the influence of the power supply and voltage fluctuations installed on site, power calculation or acquisition requires an additional power acquisition module, which is costly. In addition, since the power fluctuation deviation is basically small, and if the compressor 10 itself is worn, it will also cause power fluctuations, there is a certain misjudgment effect.

[0076] In the implementation mode of the present application, various parameters related to the liquid return of the compressor 10 are taken into consideration, and the operating frequency of the compressor 10, the fan speed of the fan 20, and the operating high pressure and the operating low pressure of the air-conditioning unit 100 are obtained in a preset cycle. It is judged whether the compressor 10 has a liquid return phenomenon based on the operating frequency, fan speed, operating high pressure and operating low pressure, and a joint judgment is made based on various parameters. When the compressor 10 has a liquid return phenomenon, the compressor 10 is protected and controlled. In this way, it is possible to accurately judge whether the compressor 10 has a liquid return phenomenon without adding other modules, and the cost is low. In addition, the compressor 10 can also be protected and controlled, effectively reducing the damage to the compressor 10 caused by the liquid return, and improving the reliability of the air-conditioning unit 100.

[0077] See also Figure 2 and Figure 3In some embodiments, the fan 20 includes an outdoor fan 21 and an indoor fan 22. The fan speed of the fan 20 (ie, 010) is obtained at a preset period, including:

[0078] 011: When the air conditioning unit 100 works in the cooling mode, a first fan speed of the outdoor fan 21 is obtained in a preset cycle as the fan speed;

[0079] 012: When the air-conditioning unit 100 operates in the heating mode, the second fan speed of the indoor fan 22 is obtained at a preset cycle as the fan speed.

[0080] Specifically, the fan 20 includes an outdoor fan 21 and an indoor fan 22. The air conditioning unit 100 also includes a four-way valve 50, an outdoor heat exchanger 61, an indoor heat exchanger 62 and a gas-liquid separator 70. The outdoor fan 21 is connected to the outdoor heat exchanger 61, and the indoor fan 22 is connected to the indoor heat exchanger 62.

[0081] When the air conditioning unit 100 operates in the cooling mode, Figure 2 As shown, the four-way valve 50 connects the compressor 10 with the outdoor heat exchanger 61, and the indoor heat exchanger 62 is connected with the gas-liquid separator 70. The high-temperature and high-pressure gaseous refrigerant discharged from the compressor 10 flows to the outdoor heat exchanger 61 through the four-way valve 50, exchanges heat with the outdoor air through the outdoor fan 21, and the high-temperature and high-pressure gaseous refrigerant is converted into a medium-temperature and high-pressure liquid refrigerant, and then flows to the indoor heat exchanger 62. The medium-temperature and high-pressure liquid refrigerant exchanges heat with the indoor air through the indoor fan 22 in the indoor heat exchanger 62, evaporates into a low-temperature and low-pressure gaseous refrigerant, flows to the gas-liquid separator 70 through the four-way valve 50, and returns to the compressor 10 after gas-liquid separation in the gas-liquid separator 70.

[0082] When the air conditioning unit 100 is working in the heating mode, the four-way valve 50 connects the compressor 10 with the indoor heat exchanger 62, and the outdoor heat exchanger 61 with the gas-liquid separator 70. The high-temperature and high-pressure gaseous refrigerant discharged from the compressor 10 flows to the indoor heat exchanger 62 through the four-way valve 50, exchanges heat with the indoor air through the indoor fan 22, and the high-temperature and high-pressure gaseous refrigerant is converted into a medium-temperature and high-pressure liquid refrigerant, and then flows to the outdoor heat exchanger 61. The medium-temperature and high-pressure liquid refrigerant exchanges heat with the outdoor air through the outdoor fan 21 in the outdoor heat exchanger 61, evaporates into a low-temperature and low-pressure gaseous refrigerant, flows to the gas-liquid separator 70 through the four-way valve 50, and returns to the compressor 10 after gas-liquid separation in the gas-liquid separator 70.

[0083] See also Figure 2 and Figure 4In some embodiments, the air conditioning unit 100 includes a first pressure sensor 31 and a second pressure sensor 32. The first pressure sensor 31 is disposed at the exhaust end of the compressor 10, and the second pressure sensor 32 is disposed at the suction end of the compressor 10. The operation high pressure and the operation low pressure (i.e., 010) of the air conditioning unit 100 are obtained in a preset cycle, including:

[0084] 013: Obtaining the operating high pressure of the air conditioning unit 100 at a preset period through the first pressure sensor 31;

[0085] 014: The operating low pressure of the air-conditioning unit 100 is obtained through the second pressure sensor 32 at a preset period.

[0086] Specifically, the air conditioning unit 100 includes a first pressure sensor 31 and a second pressure sensor 32. The first pressure sensor 31 is arranged at the exhaust end of the compressor 10, between the compressor 10 and the four-way valve 50. The exhaust end of the compressor 10 discharges a high-temperature and high-pressure gaseous refrigerant. Therefore, through the first pressure sensor 31, the operating high-pressure pressure of the air conditioning unit 100 can be obtained in a preset period. The second pressure sensor 32 is arranged at the suction end of the compressor 10, between the four-way valve 50 and the gas-liquid separator 70. The suction end of the compressor 10 inhales a low-temperature and low-pressure gaseous refrigerant. Therefore, through the second pressure sensor 32, the operating low-pressure pressure of the air conditioning unit 100 can be obtained in a preset period.

[0087] In the related art, the multi-party index of the compressor 10 is calculated by obtaining parameters such as the return air temperature, exhaust temperature, return air pressure and exhaust pressure of the compressor 10 to determine whether the compressor 10 has liquid return. This method requires the installation of multiple detection sensors such as a return air temperature sensor, an exhaust temperature sensor, a return air pressure sensor and an exhaust pressure sensor, which is relatively costly. In addition, the temperature and pressure of the refrigerant in the two-phase region can correspond, but the return air process is overheated and lacks a pressure value. The temperature alone cannot truly indicate whether the actual refrigerant is humid air or liquid return. Especially in the heating mode, the return air temperature will be lower than the outdoor coil temperature in most cases. Therefore, this method cannot determine whether the compressor 10 has liquid return.

[0088] In the implementation mode of the present application, the operating high pressure and the operating low pressure are respectively obtained by the first pressure sensor 31 and the second pressure sensor 32 configured by the air-conditioning unit 100 itself, and the operating frequency and fan speed of the compressor 10 can be obtained by direct reading. In this way, it is possible to accurately determine whether there is liquid backflow in the compressor 10 without adding other modules, and the cost is low.

[0089] See also Figure 2 and Figure 5In some embodiments, judging whether the compressor 10 has a liquid backflow phenomenon (i.e., 020) based on the operating frequency, the fan speed, the operating high pressure, and the operating low pressure includes:

[0090] 021: Calculate the difference between the operating frequency obtained at the current moment and the operating frequency obtained at the previous moment to obtain the frequency difference;

[0091] 022: Calculate the difference between the fan speed obtained at the current moment and the fan speed obtained at the previous moment to obtain the speed difference;

[0092] 023: Calculate the difference between the operating high pressure pressure obtained at the current moment and the operating high pressure pressure obtained at the previous moment to obtain the high pressure pressure difference;

[0093] 024: Calculate the difference between the operating low pressure obtained at the current moment and the operating low pressure obtained at the previous moment to obtain the low pressure difference;

[0094] 025: Determine whether there is liquid return phenomenon in the compressor 10 according to the frequency difference, the speed difference, the high pressure difference and the low pressure difference.

[0095] Specifically, the operating frequency of the compressor 10, the fan speed of the fan 20, and the operating high pressure and operating low pressure of the air conditioning unit 100 are obtained in a preset cycle. Each time the operating frequency is obtained, the difference between the operating frequency obtained at the current moment and the operating frequency obtained at the previous moment is calculated to obtain the frequency difference; the difference between the fan speed obtained at the current moment and the fan speed obtained at the previous moment is calculated to obtain the speed difference; the difference between the operating high pressure obtained at the current moment and the operating high pressure obtained at the previous moment is calculated to obtain the high pressure difference; the difference between the operating low pressure obtained at the current moment and the operating low pressure obtained at the previous moment is calculated to obtain the low pressure difference.

[0096] The frequency difference, speed difference, high-pressure difference and low-pressure difference represent the changes in the operating frequency of the compressor 10, the fan speed of the fan 20, and the operating high-pressure pressure and the operating low-pressure pressure of the air-conditioning unit 100 in a preset cycle. Based on the frequency difference, speed difference, high-pressure difference and low-pressure difference, it can be determined whether the compressor 10 has liquid backflow.

[0097] See also Figure 2 and Figure 6 In some embodiments, judging whether the compressor 10 has a liquid backflow phenomenon (ie, 020) based on the frequency difference, the speed difference, the high pressure difference, and the low pressure difference includes:

[0098] 026: when the frequency difference is zero, the speed difference is less than the preset speed difference, the high pressure difference is greater than or equal to the first pressure difference, and the low pressure difference is greater than or equal to the second pressure difference for a continuous predetermined number of preset cycles, it is determined that the compressor 10 has a liquid backflow phenomenon;

[0099] 027: When the frequency difference is not zero, and / or the speed difference is greater than or equal to the preset speed difference, and / or the high-pressure difference is less than the first pressure difference, and / or the low-pressure difference is less than the second pressure difference, it is determined that there is no liquid return phenomenon in the compressor 10.

[0100] Specifically, the predetermined number of preset cycles can be set to 3-5 preset cycles. For example, the predetermined number of preset cycles is set to 3 preset cycles. When, in 3 consecutive preset cycles, the frequency difference is zero, the speed difference is less than the preset speed difference, the high-pressure pressure difference is greater than or equal to the first pressure difference, and the low-pressure pressure difference is greater than or equal to the second pressure difference, it is determined that the compressor 10 has liquid backflow.

[0101] Among them, the preset speed difference can be set at 60-100rpm, and the specific value can be set according to the actual situation. For example, the preset difference can be set to 60rpm, 65rpm, 70rpm, 75rpm, 80rpm, 85rpm, 90rpm, 95rpm, 100rpm or any value between 60-100rpm.

[0102] The first pressure difference can be set at 0.8~1.5Bar, and the specific value can also be set according to the actual situation. For example, the first pressure difference can be set to 0.8Bar, 0.9Bar, 1.0Bar, 1.1Bar, 1.2Bar, 1.3Bar, 1.4Bar, 1.5Bar or any value between 0.8 and 1.5Bar.

[0103] The second pressure difference can be set at 0.5~1.0Bar, and the specific value can also be set according to the actual situation. For example, the second pressure difference can be set to 0.5Bar, 0.6Bar, 0.7Bar, 0.8Bar, 0.9Bar, 1.0Bar or any value between 0.5 and 1.0Bar.

[0104] In addition, when the compressor 10 has liquid backflow, the fluctuation of the operating high pressure and the operating low pressure will increase. Therefore, if the high pressure difference of the air-conditioning unit 100 is greater than or equal to the first pressure difference, and the low pressure difference is greater than or equal to the second pressure difference, it indicates that the compressor 10 may have liquid backflow.

[0105] Based on the above four parameters, a joint judgment is made on the liquid return phenomenon of the compressor 10. When the frequency difference is zero, the speed difference is less than the preset speed difference, the high-pressure pressure difference is greater than or equal to the first pressure difference, and the low-pressure pressure difference is greater than or equal to the second pressure difference in consecutive predetermined cycles, it is determined that the compressor 10 has a liquid return phenomenon.

[0106] It should be noted that, within a continuous predetermined number of preset cycles, if any one of the above four conditions is not satisfied, that is, when the frequency difference is not zero, and / or the speed difference is greater than or equal to the preset speed difference, and / or the high-pressure pressure difference is less than the first pressure difference, and / or the low-pressure pressure difference is less than the second pressure difference, it is determined that there is no liquid return phenomenon in the compressor 10.

[0107] Afterwards, the preset period is recounted until all the above four conditions are satisfied simultaneously in a continuous number of preset periods. In this way, the liquid return phenomenon of the compressor 10 can be accurately judged, and the probability of misjudgment can be reduced.

[0108] See also Figure 2 , Figure 7 and Figure 8 In some embodiments, the air conditioning unit 100 further includes an expansion valve 40, which is connected to the fan 20. When the compressor 10 has a liquid backflow phenomenon, the compressor 10 is protected and controlled (ie, 030), including:

[0109] 031: When liquid backflow occurs in the compressor 10, the compressor 10 is protected and controlled by correcting and controlling the opening of the expansion valve 40, the superheat and the operating frequency of the compressor 10.

[0110] Specifically, the air conditioning unit 100 further includes an expansion valve 40, and the expansion valve 40 includes a first expansion valve 41 and a second expansion valve 42. The first expansion valve 41 is connected to the outdoor fan 21, and when the air conditioning unit 100 works in the cooling mode, the first expansion valve 41 plays a throttling role. The second expansion valve 42 is connected to the indoor fan 22, and when the air conditioning unit 100 works in the heating mode, the second expansion valve 42 plays a throttling role. When the compressor 10 has a liquid backflow phenomenon, the compressor 10 can be protected and controlled by correcting and controlling the opening of the expansion valve 40, the superheat of the compressor 10, and the operating frequency.

[0111] It should be noted that when the air conditioning unit 100 works in different modes, different expansion valves 40 are corrected and controlled. When the air conditioning unit 100 works in the cooling mode, the opening of the second expansion valve is corrected and controlled; when the air conditioning unit 100 works in the heating mode, the opening of the first expansion valve 41 is corrected and controlled.

[0112] See also Figure 2 , Figure 8 and Fig. 9 In some embodiments, when the compressor 10 has liquid backflow, the compressor 10 is protected and controlled (i.e., 031) by correcting and controlling the superheat of the compressor 10, the opening degree of the expansion valve 40, and the operating frequency, including:

[0113] 0311: When the compressor 10 has liquid backflow, the opening of the expansion valve 40 is reduced to increase the exhaust superheat and the suction superheat of the compressor 10, and the step of obtaining the operating frequency of the compressor 10, the fan speed of the fan 20, and the operating high pressure and the operating low pressure of the air conditioning unit 100 in a preset cycle is returned to determine again whether the compressor 10 has liquid backflow;

[0114] 0312: When it is determined again that the compressor 10 has a liquid backflow phenomenon, it is determined whether the opening degree of the expansion valve 40 is equal to the preset opening degree;

[0115] 0313: When the opening of the expansion valve 40 is not equal to the preset opening, return to the step of reducing the opening of the expansion valve 40 to increase the exhaust superheat and the suction superheat of the compressor 10;

[0116] 0314: When the opening degree of the expansion valve 40 is equal to the preset opening degree, the operating frequency is reduced;

[0117] 0315: Determine whether to enable unit protection based on the reduced operating frequency.

[0118] Specifically, when liquid backflow occurs in the compressor 10, the expansion valve 40 that needs to be regulated is determined according to the working mode of the air-conditioning unit 100, and the opening of the expansion valve 40 is reduced. The reduced opening can be 40-80 steps, and the specific number of steps can be set according to actual conditions. For example, the reduced opening can be 40 steps, 45 steps, 50 steps, 55 steps, 60 steps, 65 steps, 70 steps, 75 steps, 80 steps or any number of steps between 40 and 80 steps.

[0119] Taking the air conditioning unit 100 working in the cooling mode as an example, at this time, the opening of the second expansion valve 42 is reduced, and the liquid refrigerant entering the indoor heat exchanger 62 will be reduced accordingly, so that the liquid refrigerant in the indoor heat exchanger 62 evaporates more fully, reducing the possibility of the liquid refrigerant continuing to evaporate in the suction pipe of the compressor 10. Therefore, the refrigerant temperature in the suction pipe will rise, that is, the suction temperature rises, thereby increasing the suction superheat.

[0120] Since reducing the opening of the second expansion valve 42 increases the intake temperature, and the intake temperature is a direct antecedent of the exhaust temperature, the exhaust temperature will also rise accordingly, thereby increasing the exhaust superheat.

[0121] After increasing the exhaust superheat and suction superheat of the compressor 10, return to the step (i.e., 010) of obtaining the operating frequency of the compressor 10, the fan speed of the fan 20, and the operating high pressure and operating low pressure of the air-conditioning unit 100 in a preset cycle to determine again whether there is liquid backflow in the compressor 10.

[0122] When it is determined again that the compressor 10 has a liquid backflow phenomenon, it indicates that the air conditioning unit 100 needs to be protected and controlled. Since the opening of the expansion valve 40 has been reduced, it is necessary to first determine whether the opening of the expansion valve 40 is equal to the preset opening to determine whether the opening of the expansion valve 40 can be further reduced. The preset opening can be set to the minimum opening allowed by the expansion valve 40, and the range of the minimum opening is 40-50 steps. For example, the preset opening can be set to 40 steps, 42 steps, 44 steps, 46 steps, 48 ​​steps, 50 steps, or any number of steps between 40 and 50 steps.

[0123] When the opening of the expansion valve 40 is not equal to the preset opening, it indicates that protection control can be performed by continuing to reduce the opening of the expansion valve 40. Therefore, the step of reducing the opening of the expansion valve 40 to increase the exhaust superheat and intake superheat of the compressor 10 is returned (ie, 0311).

[0124] When the opening of the expansion valve 40 is equal to the preset opening, it means that the opening of the expansion valve 40 cannot be further reduced. At this time, the air conditioning unit 100 can be protected and controlled by reducing the operating frequency of the compressor 10. The operating frequency of the compressor 10 can be reduced by a preset frequency, which can be set to 8-20Hz. The specific frequency can be set according to actual conditions. For example, the preset frequency can be set to 8Hz, 10Hz, 12Hz, 14Hz, 16Hz, 18Hz, 20Hz or any frequency between 8-20Hz. After reducing the operating frequency of the compressor 10, it is determined whether the unit protection needs to be turned on according to the reduced operating frequency.

[0125] See also Figure 2 , Figure 8 and Fig.10 In some embodiments, after determining again whether the compressor 10 has a liquid return phenomenon (ie, 0311), the liquid return control method of the compressor 10 further includes:

[0126] 0316: When there is no liquid return phenomenon in the compressor 10, the compressor 10 is controlled to maintain the exhaust gas superheat and the suction gas superheat at the current moment.

[0127] Specifically, after judging again whether the compressor 10 has the liquid backflow phenomenon, if it is judged that the compressor 10 does not have the liquid backflow phenomenon, it means that the operation of reducing the opening of the expansion valve 40 effectively solves the problem of liquid backflow in the compressor 10. At this time, the compressor 10 is controlled to maintain the exhaust gas superheat and the suction gas superheat at the current moment, which are the exhaust gas superheat and the suction gas superheat increased by reducing the opening of the expansion valve 40.

[0128] See also Figure 2 , Figure 8 and Fig.11 In some implementations, judging whether it is necessary to start unit protection (i.e., 0315) according to the reduced operating frequency includes:

[0129] 03151: Determine whether the reduced operating frequency is equal to the frequency threshold;

[0130] 03152: When the reduced operating frequency is less than or equal to the frequency threshold, the frequency threshold is maintained and the unit protection is turned on;

[0131] 03153: When the reduced operating frequency is greater than the frequency threshold, return to the step of obtaining the operating frequency of the compressor 10, the fan speed of the fan 20, and the operating high pressure and the operating low pressure of the air-conditioning unit 100 at a preset period, so as to determine again whether there is a liquid backflow phenomenon in the compressor 10;

[0132] 03154: When it is determined again that the compressor 10 has liquid backflow, return to the step of reducing the operating frequency;

[0133] 03155: When there is no liquid return phenomenon in the compressor 10, the compressor 10 is controlled to maintain the current operating frequency, exhaust superheat and suction superheat.

[0134] Specifically, after reducing the operating frequency of the compressor 10, it is determined whether the reduced operating frequency is equal to the frequency threshold. The frequency threshold can be set to the minimum operating frequency allowed by the compressor 10. The range of the minimum operating frequency is 10-20 Hz, for example, the frequency threshold can be set to 10 Hz, 12 Hz, 14 Hz, 16 Hz, 18 Hz, 20 Hz or any frequency between 10-20 Hz.

[0135] When the reduced operating frequency is less than or equal to the frequency threshold, the compressor 10 cannot operate at the reduced operating frequency, and at this time, the compressor 10 still has liquid backflow. At this time, the unit protection is turned on, and the unit protection includes stopping the operation of the air-conditioning unit 100, issuing a fault alarm signal, and sending fault information to the customer.

[0136] When the reduced operating frequency is greater than the frequency threshold, the process returns to the step of obtaining the operating frequency of the compressor 10, the fan speed of the fan 20, and the operating high pressure and the operating low pressure of the air conditioning unit 100 in a preset cycle to again determine whether there is a liquid backflow phenomenon in the compressor 10. When it is determined again that there is a liquid backflow phenomenon in the compressor 10, it means that the air conditioning unit 100 needs to be protected and controlled, and at this time the opening degree of the expansion valve 40 is already the minimum opening degree, so the process returns to the step of reducing the operating frequency.

[0137] When there is no liquid backflow phenomenon in the compressor 10, it means that the operation of reducing the operating frequency effectively solves the problem of liquid backflow in the compressor 10, and the compressor 10 is controlled to maintain the current operating frequency.

[0138] See also Figure 2 and Fig.12 The embodiment of the present application also provides a compressor 10 liquid return control device 200, which is applied to the air conditioning unit 100. The air conditioning unit 100 includes a compressor 10 and a fan 20, and the compressor 10 liquid return control device 200 includes an acquisition module 210, a judgment module 220 and a control module 230. The acquisition module 210 is used to acquire the operating frequency of the compressor 10, the fan speed of the fan 20, and the operating high pressure and operating low pressure of the air conditioning unit 100 in a preset cycle. The judgment module 220 is used to judge whether the compressor 10 has a liquid return phenomenon according to the operating frequency, fan speed, operating high pressure and operating low pressure. The control module 230 is used to protect and control the compressor 10 when the compressor 10 has a liquid return phenomenon.

[0139] In some embodiments, the fan 20 includes an outdoor fan 21 and an indoor fan 22. The acquisition module 210 is specifically used to acquire a first fan speed of the outdoor fan 21 at a preset cycle as the fan speed when the air-conditioning unit 100 works in the cooling mode; and to acquire a second fan speed of the indoor fan 22 at a preset cycle as the fan speed when the air-conditioning unit 100 works in the heating mode.

[0140] In some embodiments, the air conditioning unit 100 includes a first pressure sensor 31 and a second pressure sensor 32, wherein the first pressure sensor 31 is disposed at the exhaust end of the compressor 10, and the second pressure sensor 32 is disposed at the suction end of the compressor 10. The acquisition module 210 is specifically configured to acquire the operating high pressure of the air conditioning unit 100 at a preset period through the first pressure sensor 31; and acquire the operating low pressure of the air conditioning unit 100 at a preset period through the second pressure sensor 32.

[0141] In some embodiments, the judgment module 220 is specifically used to calculate the difference between the operating frequency obtained at the current moment and the operating frequency obtained at the previous moment to obtain a frequency difference; calculate the difference between the fan speed obtained at the current moment and the fan speed obtained at the previous moment to obtain a speed difference; calculate the difference between the operating high pressure pressure obtained at the current moment and the operating high pressure pressure obtained at the previous moment to obtain a high pressure pressure difference; calculate the difference between the operating low pressure pressure obtained at the current moment and the operating low pressure pressure obtained at the previous moment to obtain a low pressure pressure difference; and determine whether the compressor 10 has liquid backflow based on the frequency difference, speed difference, high pressure difference and low pressure difference.

[0142] In some embodiments, the judgment module 220 is specifically used to determine that the compressor 10 has liquid backflow when the frequency difference is zero, the speed difference is less than the preset speed difference, the high-pressure pressure difference is greater than or equal to the first pressure difference, and the low-pressure pressure difference is greater than or equal to the second pressure difference in a continuous predetermined number of preset periods; when the frequency difference is not zero, and / or the speed difference is greater than or equal to the preset speed difference, and / or the high-pressure pressure difference is less than the first pressure difference, and / or the low-pressure pressure difference is less than the second pressure difference, it is determined that the compressor 10 does not have liquid backflow.

[0143] In some embodiments, the air conditioning unit 100 further includes an expansion valve 40, which is connected to the fan 20. The control module 230 is specifically used to protect and control the compressor 10 by correcting and controlling the superheat of the compressor 10, the opening degree of the expansion valve 40, and the operating frequency when the compressor 10 has liquid backflow.

[0144] In some embodiments, the control module 230 is specifically used to reduce the opening of the expansion valve 40 when the compressor 10 has liquid backflow, so as to increase the exhaust superheat and intake superheat of the compressor 10, and return to the step of obtaining the operating frequency of the compressor 10, the fan speed of the fan 20, and the operating high pressure and the operating low pressure of the air-conditioning unit 100 in a preset period to determine again whether the compressor 10 has liquid backflow; when it is determined again that the compressor 10 has liquid backflow, determine whether the opening of the expansion valve 40 is equal to the preset opening; when the opening of the expansion valve 40 is not equal to the preset opening, return to the step of reducing the opening of the expansion valve 40 to increase the exhaust superheat and intake superheat of the compressor 10; when the opening of the expansion valve 40 is equal to the preset opening, reduce the operating frequency; and determine whether it is necessary to turn on the unit protection according to the reduced operating frequency.

[0145] In some embodiments, after determining again whether the compressor 10 has liquid backflow, the control module 230 is further configured to control the compressor 10 to maintain the exhaust gas superheat and suction gas superheat at the current moment when the compressor 10 does not have liquid backflow.

[0146] In some embodiments, the control module 230 is specifically used to determine whether the reduced operating frequency is equal to the frequency threshold; when the reduced operating frequency is less than or equal to the frequency threshold, the unit protection is turned on; when the reduced operating frequency is greater than the frequency threshold, the step of obtaining the operating frequency of the compressor 10, the fan speed of the fan 20, and the operating high pressure and the operating low pressure of the air-conditioning unit 100 in a preset period is returned to determine again whether the compressor 10 has a liquid backflow phenomenon; when it is determined again that the compressor 10 has a liquid backflow phenomenon, the step of reducing the operating frequency is returned; when the compressor 10 does not have a liquid backflow phenomenon, the compressor 10 is controlled to maintain the current operating frequency, exhaust superheat and suction superheat.

[0147] It should be pointed out that the explanation of the liquid return control method of the compressor 10 in the aforementioned embodiment is also applicable to the liquid return control device 200 of the compressor 10 in the embodiment of the present application, and will not be elaborated here.

[0148] See also Fig.13 The embodiment of the present application also provides a compressor 10 liquid return control system 300, the compressor 10 liquid return control system 300 includes one or more processors 310 and a memory 320, the memory 320 stores a computer program, and when the computer program is executed by the processor 310, the compressor 10 liquid return control method of any of the above embodiments is implemented.

[0149] For example, when the computer program is executed by the processor 310, the following liquid return control method of the compressor 10 is implemented:

[0150] 010: Obtaining the operating frequency of the compressor 10, the fan speed of the fan 20, and the operating high pressure and the operating low pressure of the air conditioning unit 100 at a preset period;

[0151] 020: Determine whether there is liquid backflow in the compressor 10 according to the operating frequency, fan speed, operating high pressure and operating low pressure;

[0152] 030: When liquid backflow occurs in the compressor 10, protection control is performed on the compressor 10.

[0153] For another example, when the computer program is executed by the processor 310, the following liquid return control method of the compressor 10 is implemented:

[0154] 011: When the air conditioning unit 100 works in the cooling mode, a first fan speed of the outdoor fan 21 is obtained in a preset cycle as the fan speed;

[0155] 012: When the air-conditioning unit 100 operates in the heating mode, the second fan speed of the indoor fan 22 is obtained at a preset cycle as the fan speed.

[0156] It should be pointed out that the explanations and descriptions of the compressor 10 liquid return control method and the compressor 10 liquid return control device 200 in the aforementioned embodiment are also applicable to the compressor 10 liquid return control system 300 in the embodiment of the present application, and will not be elaborated here.

[0157] See also Fig.14 The embodiment of the present application further provides a computer-readable storage medium 400 on which a computer program 410 is stored. When the program is executed by a processor 420, the liquid return control method of the compressor 10 of any of the above embodiments is implemented.

[0158] For example, when the computer program 410 is executed by the processor 420, the following liquid return control method of the compressor 10 is implemented:

[0159] 010: Obtaining the operating frequency of the compressor 10, the fan speed of the fan 20, and the operating high pressure and the operating low pressure of the air conditioning unit 100 at a preset period;

[0160] 020: Determine whether there is liquid backflow in the compressor 10 according to the operating frequency, fan speed, operating high pressure and operating low pressure;

[0161] 030: When liquid backflow occurs in the compressor 10, protection control is performed on the compressor 10.

[0162] For another example, when the computer program 410 is executed by the processor 420, the following liquid return control method of the compressor 10 is implemented:

[0163] 011: When the air conditioning unit 100 works in the cooling mode, a first fan speed of the outdoor fan 21 is obtained in a preset cycle as the fan speed;

[0164] 012: When the air-conditioning unit 100 operates in the heating mode, the second fan speed of the indoor fan 22 is obtained at a preset cycle as the fan speed.

[0165] It should be noted that the explanations and descriptions of the compressor 10 liquid return control method and the compressor 10 liquid return control device 200 in the aforementioned embodiments are also applicable to the computer-readable storage medium 400 in the embodiments of the present application, and will not be elaborated here.

[0166] In summary, in the compressor 10 liquid return control method, control device 200, control system 300 and computer-readable storage medium 400 of the embodiment of the present application, the operating frequency of the compressor 10, the fan speed of the fan 20, and the operating high pressure and operating low pressure of the air-conditioning unit 100 are obtained in a preset cycle, and whether the compressor 10 has liquid return phenomenon is judged according to the operating frequency, fan speed, operating high pressure and operating low pressure, and a joint judgment is made based on a combination of multiple parameters, and when the compressor 10 has liquid return phenomenon, the compressor 10 is protected and controlled. In this way, it is possible to accurately judge whether the compressor 10 has liquid return phenomenon without adding other modules, and the cost is low. In addition, the compressor 10 can also be protected and controlled, effectively reducing the damage caused by liquid return to the compressor 10, and improving the reliability of the air-conditioning unit 100.

[0167] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0168] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0169] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable storage medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, a computer-readable storage medium can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples (non-exhaustive list) of computer-readable storage media include the following: an electrical connection with one or more wires (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable storage medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0170] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0171] A person of ordinary skill in the art will appreciate that all or part of the steps carried by the method for implementing the above-mentioned embodiment can be completed by instructing the relevant hardware through a program, and the program can be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment. In addition, each functional unit in each embodiment of the present application can be integrated into a processing module, or each unit can exist physically alone, or two or more units can be integrated into one module. The above-mentioned integrated module can be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. The above-mentioned storage medium can be a read-only memory, a disk or an optical disk, etc.

[0172] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application. The scope of the present application is defined by the claims and their equivalents.

Claims

1. A compressor liquid return control method, characterized in that: Applied to an air conditioning unit, the air conditioning unit includes a compressor and a fan, and the compressor liquid return control method includes: Acquiring the operating frequency of the compressor, the fan speed of the fan, and the operating high pressure and the operating low pressure of the air conditioning unit at a preset period; Determining whether the compressor has liquid backflow according to the operating frequency, the fan speed, the operating high pressure, and the operating low pressure; When liquid backflow occurs in the compressor, protection control is performed on the compressor.

2. The compressor liquid return control method according to claim 1, characterized in that: The fan includes an outdoor fan and an indoor fan, and the fan speed of the fan is obtained in a preset cycle, including: When the air-conditioning unit operates in a cooling mode, obtaining a first fan speed of the outdoor fan in the preset cycle as the fan speed; When the air-conditioning unit operates in a heating mode, a second fan speed of the indoor fan is obtained in the preset cycle as the fan speed.

3. The compressor liquid return control method according to claim 1, characterized in that: The air conditioning unit comprises a first pressure sensor and a second pressure sensor, wherein the first pressure sensor is arranged at the exhaust end of the compressor, and the second pressure sensor is arranged at the suction end of the compressor, and the operating high pressure and the operating low pressure of the air conditioning unit are obtained in a preset cycle, including: obtaining the operating high pressure of the air conditioning unit at the preset period through the first pressure sensor; The operating low pressure of the air-conditioning unit is obtained at the preset period through the second pressure sensor.

4. The compressor liquid return control method according to claim 1, characterized in that: The determining whether the compressor has liquid backflow according to the operating frequency, the fan speed, the operating high pressure and the operating low pressure includes: Calculate the difference between the operating frequency obtained at the current moment and the operating frequency obtained at the previous moment to obtain a frequency difference; Calculate the difference between the fan speed obtained at the current moment and the fan speed obtained at the previous moment to obtain a speed difference; Calculating the difference between the operating high pressure pressure obtained at the current moment and the operating high pressure pressure obtained at the previous moment to obtain a high pressure pressure difference; Calculating the difference between the operating low pressure obtained at the current moment and the operating low pressure obtained at the previous moment to obtain a low pressure difference; It is determined whether liquid backflow occurs in the compressor according to the frequency difference, the speed difference, the high-pressure difference and the low-pressure difference.

5. The compressor liquid return control method according to claim 4, characterized in that: The determining whether the compressor has liquid backflow according to the frequency difference, the speed difference, the high pressure difference and the low pressure difference comprises: When, in a predetermined number of consecutive preset cycles, the frequency difference is zero, the speed difference is less than the preset speed difference, the high-pressure difference is greater than or equal to the first pressure difference, and the low-pressure difference is greater than or equal to the second pressure difference, it is determined that the compressor has liquid backflow; When the frequency difference is not zero, and / or the speed difference is greater than or equal to the preset speed difference, and / or the high-pressure pressure difference is less than the first pressure difference, and / or the low-pressure pressure difference is less than the second pressure difference, it is determined that there is no liquid return phenomenon in the compressor.

6. The compressor liquid return control method according to claim 1, characterized in that: The air conditioning unit further includes an expansion valve, which is connected to the fan. When the compressor has liquid backflow, the compressor is protected and controlled, including: When liquid backflow occurs in the compressor, the compressor is protected and controlled by correcting and controlling the opening of the expansion valve, the superheat of the compressor and the operating frequency.

7. The compressor liquid return control method according to claim 6, characterized in that: When the compressor has a liquid backflow phenomenon, the compressor is protected and controlled by correcting and controlling the opening of the expansion valve, the superheat of the compressor and the operating frequency, including: When the compressor has liquid backflow, the opening of the expansion valve is reduced to increase the exhaust superheat and suction superheat of the compressor, and the step of obtaining the operating frequency of the compressor, the fan speed of the fan, and the operating high pressure and the operating low pressure of the air conditioning unit in a preset cycle is returned to determine again whether the compressor has liquid backflow; When it is determined again that the compressor has a liquid backflow phenomenon, determining whether the opening of the expansion valve is equal to a preset opening; When the opening of the expansion valve is not equal to the preset opening, returning to the step of reducing the opening of the expansion valve to increase the exhaust superheat and suction superheat of the compressor; When the opening degree of the expansion valve is equal to the preset opening degree, reducing the operating frequency; Whether it is necessary to start unit protection is determined based on the reduced operating frequency.

8. The compressor liquid return control method according to claim 7, characterized in that: After determining again whether the compressor has liquid return phenomenon, the compressor liquid return control method further includes: When there is no liquid return phenomenon in the compressor, the compressor is controlled to operate while maintaining the exhaust gas superheat and the suction gas superheat at the current moment.

9. The compressor liquid return control method according to claim 7, characterized in that: The determining whether it is necessary to start unit protection according to the reduced operating frequency includes: Determining whether the reduced operating frequency is equal to a frequency threshold; When the reduced operating frequency is less than or equal to the frequency threshold, maintaining the frequency threshold operation and starting unit protection; When the reduced operating frequency is greater than the frequency threshold, returning to the step of obtaining the operating frequency of the compressor, the fan speed of the fan, and the operating high pressure and the operating low pressure of the air-conditioning unit at a preset period, to again determine whether there is liquid backflow in the compressor; When it is determined again that the compressor has liquid backflow, returning to the step of reducing the operating frequency; When there is no liquid return phenomenon in the compressor, the compressor is controlled to maintain the operating frequency, the exhaust superheat and the suction superheat at the current moment.

10. A compressor liquid return control system, characterized in that: The compressor liquid return control system includes one or more processors and a memory, wherein the memory stores a computer program, and when the computer program is executed by the processor, the compressor liquid return control method according to any one of claims 1 to 9 is implemented.

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