Refrigerant circulation system and control method thereof, and air conditioning unit

Abstract

The present invention relates to a refrigerant circulation system and a control method thereof, and an air conditioning unit, wherein the refrigerant circulation system includes a compressor and a first control valve, the compressor includes an inlet and an air supply port, the first control valve is arranged on a connecting passage between the air supply port and the inlet, wherein the refrigerant circulation system has a first heating mode, in which the second expansion valve is closed, the first expansion valve and the first control valve are both opened, the air supply port, the first control valve and the inlet are connected in sequence to form a first self-circulation passage, so as to increase the internal temperature of the compressor.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning, and in particular to a refrigerant circulation system and a control method thereof, and an air conditioning unit. Background Art

[0002] With the deepening and refinement of the country's "carbon neutrality", photovoltaic heat pump multi-split has become one of the important ways to achieve energy conservation and emission reduction. Since photovoltaic heat pump multi-split mainly relies on the "photovoltaic to electrical" energy method to realize the operation of the unit, it reduces the power consumption of the national power grid and also reduces the carbon emissions during thermal power generation.

[0003] However, in actual use, photovoltaic multi-split systems often fail to generate heat for a long time.

[0004] It should be noted that the information disclosed in the background technology section of the present invention is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes prior art already known to those skilled in the art. Summary of the invention

[0005] The embodiments of the present invention provide a refrigerant circulation system and a control method thereof, and an air-conditioning unit, which solve the problem in the related art that the air-conditioning unit does not heat for a long time due to the outdoor unit being in a low-temperature environment for a long time, the user's usage habits being restricted, or a large amount of liquid refrigerant remaining in the outdoor unit.

[0006] According to a first aspect of the present invention, there is provided a refrigerant circulation system, comprising:

[0007] Compressor, including inlet and make-up air ports; and

[0008] A first control valve is arranged on the connection passage between the inlet and the air supply port;

[0009] Among them, the refrigerant circulation system has a first heating mode. In the first heating mode, the first control valve is opened, and the air supply port, the first control valve and the inlet are connected in sequence to form a first self-circulation passage.

[0010] In some embodiments, the refrigerant circulation system further includes a first expansion valve disposed between the air supply port and the first control valve.

[0011] In some embodiments, the refrigerant circulation system also includes an outdoor heat exchanger and a gas-liquid separator, and the compressor also includes an outlet. In the first heating mode, the outlet, the outdoor heat exchanger, the first control valve, the gas-liquid separator and the inlet are connected in sequence to form a second self-circulation passage.

[0012] In some embodiments, the refrigerant circulation system also includes a power supply, the compressor includes a rotor and a stator, and the refrigerant circulation system has a second heating mode. In the second heating mode, the power supply is electrically connected to the stator to energize the windings of the stator and dissipate heat.

[0013] In some embodiments, the refrigerant circulation system further includes a control device, which is connected to the first control valve and the power supply signal, and is used to adjust the refrigerant circulation system to the first heating mode or the second heating mode.

[0014] In some embodiments, the refrigerant circulation system also includes a heating belt, which is wrapped around the outer circumference of the part to be heated of the refrigerant circulation system. The refrigerant circulation system has a third heating mode. In the third heating mode, the heating belt is started to heat the part to be heated through the heating belt.

[0015] In some embodiments, the portion to be heated includes the bottom of the compressor; alternatively, the refrigerant circulation system further includes an oil-gas separator connected to the outlet, and the portion to be heated includes the bottom of the oil-gas separator; alternatively, the refrigerant circulation system further includes a gas-liquid separator connected to the inlet, and the portion to be heated includes the bottom of the gas-liquid separator.

[0016] In some embodiments, the refrigerant circulation system further includes a control device, which is connected to the first control valve and the heating belt signal, and the control device is used to adjust the refrigerant circulation system to the first heating mode or the third heating mode.

[0017] In some embodiments, the refrigerant circulation system also includes a control device and a heating belt, the heating belt is wrapped around the periphery of the part to be heated of the refrigerant circulation system, and the refrigerant circulation system has a third heating mode. In the third heating mode, the heating belt is started to heat the part to be heated through the heating belt. The control device is connected to the first control valve, the power supply and the heating belt signal, and the control device is used to adjust the refrigerant circulation system to the first heating mode, the second heating mode or the third heating mode.

[0018] According to a second aspect of the present invention, there is provided an air conditioning unit comprising the above-mentioned refrigerant circulation system.

[0019] According to a third aspect of the present invention, a control method based on the above-mentioned refrigerant circulation system is provided, comprising:

[0020] Detect the internal temperature of the compressor;

[0021] Select the heating mode according to the internal temperature of the compressor;

[0022] When the selected heating mode is the first heating mode, open the first control valve so that the air supply port, the first control valve and the inlet are connected in sequence to form a first self-circulation passage, and the refrigerant in the refrigerant circulation system circulates in the first self-circulation passage.

[0023] In some embodiments, the control method further comprises:

[0024] Providing a power supply, the compressor includes a rotor and a stator;

[0025] When the selected heating mode is the second heating mode, the power supply is connected to the stator, the winding of the stator is energized and radiates heat to increase the internal temperature of the compressor.

[0026] In some embodiments, it also includes:

[0027] Providing a heating belt, the heating belt is wrapped around the outer periphery of the part to be heated of the refrigerant circulation system;

[0028] When the selected heating mode is the third heating mode, the heating belt is started to heat the portion to be heated.

[0029] In some embodiments, according to the internal temperature of the compressor, the operation of selecting the heating mode includes:

[0030] Determining whether the internal temperature of the compressor meets a first preset condition;

[0031] When the internal temperature of the compressor meets the first preset condition, the second heating mode and the third heating mode are started simultaneously;

[0032] If the first preset condition is not met, then continue to determine whether the internal temperature of the compressor meets the second preset condition;

[0033] If the second preset condition is met, the first heating mode and the third heating mode are activated.

[0034] In some embodiments, the first preset condition includes: within a continuous period of time t2, the internal temperature of the compressor is greater than or equal to T2 and less than T1; the second preset condition includes: within a continuous period of time t3, the internal temperature of the compressor is less than T2, wherein t1 <t2<t3,T1> T2.

[0035] In some embodiments, before determining whether the internal temperature of the compressor satisfies the first preset condition, the operation of selecting the heating mode according to the internal temperature of the compressor further includes:

[0036] Determining whether the refrigerant circulation system meets the third preset condition;

[0037] When the refrigerant circulation system meets the third preset condition, the preheating function is started;

[0038] After the preheating function is turned on, determining whether the internal temperature of the compressor meets a fourth preset condition;

[0039] If the internal temperature of the compressor meets the fourth preset condition, no heating mode is started; if the internal temperature of the compressor does not meet the fourth preset condition, the step of determining whether the internal temperature of the compressor meets the first preset condition is entered.

[0040] In some embodiments, the refrigerant circulation system includes a photovoltaic power generation device that provides electricity, and the third preset condition includes: the refrigerant circulation system is powered on for the first time or has been powered on and the standby time exceeds t0, and the power generation voltage of the photovoltaic power generation device is not less than the preset voltage value; the fourth preset condition includes: within a continuous time of t1, the internal temperature of the compressor is not less than T1.

[0041] In some embodiments, according to the internal temperature of the compressor, the operation of selecting the heating mode further comprises:

[0042] After starting the first heating mode and the third heating mode, determining whether the internal temperature of the compressor meets a fifth preset condition;

[0043] When the internal temperature of the compressor satisfies a fifth preset condition, the preheating function is turned off.

[0044] In some embodiments, the fifth preset condition includes:

[0045] When the operation time of the first heating mode and the third heating mode reaches t4, the difference between the internal temperature of the compressor and the outdoor ambient temperature is greater than T3; or

[0046] During the continuous time of t4, the internal temperature of the compressor is not less than T4.

[0047] In some embodiments, in the second heating mode, the control method further includes:

[0048] When the refrigerant circulation system is in standby mode, the heating demand of the indoor unit is zero, and the continuous downtime of the compressor is less than t5, the electrical connection between the power supply and the stator is disconnected;

[0049] When the refrigerant circulation system is in standby mode, the internal temperature of the compressor is greater than or equal to T5 and less than T6 for a continuous period of time t6, and when the compressor is powered on for the first time or has been powered on and the standby time exceeds t7, the power supply is electrically connected to the stator.

[0050] In some embodiments, in the second heating mode, the control method further includes:

[0051] After starting the second heating mode, before measuring the internal temperature of the compressor or when the difference between the internal temperature of the compressor and the outdoor ambient temperature is not greater than T7, the current of the stator winding satisfies: A1 = a*T0 2 +b*T0+c, where T0 is the outdoor ambient temperature, and a, b and c are all constants;

[0052] When the difference between the internal temperature of the compressor and the outdoor ambient temperature is greater than T7, the current of the stator winding satisfies: A2=A0*(1+d), where A0 is the current current, d is the periodic change of the internal temperature of the compressor, and d is a constant.

[0053] Based on the above technical scheme, the embodiment of the present invention can realize the heating function of the compressor by setting a first self-circulation passage, through part of the pipeline of the outdoor unit for self-circulation while the indoor unit remains in a non-operating state, thereby effectively increasing the internal temperature of the compressor, and quickly driving the flow of liquid refrigerant retained in components such as the outdoor heat exchanger. In this way, when the outdoor temperature is low, the user is accustomed to shutting down the air-conditioning unit at night, or the air-conditioning unit is left unused for a long time, the time for the air-conditioning unit to start heating can be shortened, which is also beneficial to protecting the compressor and increasing the service life of the compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0055] Figure 1 The schematic diagram of an embodiment of the refrigerant circulation system of the present invention.

[0056] Figure 2 The present invention is a flowchart of a control method for a refrigerant circulation system according to an embodiment of the present invention.

[0057] Figure 3 This is a flow chart of the second heating mode in one embodiment of the control method of the refrigerant circulation system of the present invention.

[0058] In the figure:

[0059] 1. Compressor; 2. Indoor heat exchanger; 3. Outdoor heat exchanger; 4. Subcooler; 5. First expansion valve; 6. First control valve; 7. Second expansion valve; 81. First heating zone; 82. Second heating zone; 83. Third heating zone; 9. Gas-liquid separator; 10. Oil-gas separator; 11. Control device; 12. Photovoltaic power generation device; 13. Load; 14. Four-way valve; 15. Third expansion valve; 16. Fourth expansion valve; 17. Second control valve; 18. Third control valve. DETAILED DESCRIPTION

[0060] The technical solutions in the embodiments will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0061] In the description of the present invention, it should be understood that the terms "center", "lateral", "longitudinal", "front", "back", "left", "right", "up", "down", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present invention.

[0062] In view of the phenomenon that photovoltaic multi-split systems often fail to heat for a long time, the inventor conducted in-depth research and found that the main reasons for this phenomenon are:

[0063] 1. The outdoor unit and pipelines are in a low-temperature environment for a long time: The outdoor unit of the multi-split unit is generally placed outdoors, and the connecting pipes between the indoor and outdoor units are relatively long. Although they are wrapped with thermal insulation cotton, they are still in direct contact with the low-temperature environment;

[0064] 2. Constraints of user requirements or habits: In winter, the temperature is low. Some commercial places will shut down or cut off the power supply of the air-conditioning unit after get off work and turn it on again the next day. The unit cannot continue to heat. The unit quickly cools to the ambient temperature. When it is turned on again, the unit will not heat for a long time;

[0065] 3. After being stored for a long time, the refrigerant cools down, and there is a large amount of liquid refrigerant in the outdoor unit and the long connecting pipe. When the machine is turned on the next day, the liquid refrigerant in the outdoor unit and the long connecting pipe must be heated first. This heating process will take a long time and affect the heating speed.

[0066] Based on the above findings, the inventor believes that the problem of photovoltaic heat pump multi-split units not heating for a long time should first be solved by the problem of being in a shutdown or power-off state for a long time in a low temperature environment. The specific analysis is as follows:

[0067] A. Reasons for not heating at low temperatures: The heating of air source heat pumps relies on the compressor to generate high-temperature and high-pressure gaseous refrigerant, which transfers heat to the room through the indoor heat exchanger. After being placed at low temperatures for a long time, a large amount of refrigerant has turned into liquid refrigerant. The heat generated by the compressor must first be used to heat this part of the liquid refrigerant, which greatly consumes the heating time. Moreover, in extremely low temperature conditions, due to the low ambient temperature, the system low pressure is too low. Due to the system's own protection function, the compressor will be limited from further frequency increase, further causing the heating to rise slowly.

[0068] B. It will also cause great harm and impact to the compressor:

[0069] 1. The lubricating oil of the compressor is diluted by the liquid refrigerant. Because the liquid refrigerant constantly migrates to the inside of the compressor, and under low temperature conditions, the oil and the refrigerant are miscible, which is equivalent to diluting the oil. Therefore, it will cause oil shortage when the compressor starts, which will cause internal wear;

[0070] 2. Prolong the time to achieve the heating effect. Since the liquid refrigerant must be heated first, it will directly affect the comfort;

[0071] 3. Low temperature conditions will also cause the viscosity of the oil to increase, which will cause internal wear of the compressor.

[0072] For example, when the compressor is in the low-temperature standby stage, as the pressure and oil superheat decrease, the more refrigerant there is in the oil pool, the lower the dissolved viscosity, which is not conducive to the reliability of the compressor; in the low-temperature heating startup stage, at startup, the exhaust pressure of the compressor rises rapidly, while the temperature change of the compressor is relatively slow, so the oil superheat is low for a period of time after startup; and in the stable operation stage, the oil discharge rate of the compressor is high and the system pressure difference is large, and there is a risk of failure to return oil smoothly or liquid hammer.

[0073] Therefore, the inventors have improved the refrigerant circulation system.

[0074] like Figure 1 As shown, in some embodiments of the refrigerant circulation system provided by the present invention, the refrigerant circulation system includes a compressor 1 and a first control valve 6, the compressor 1 includes an inlet 1a and an air supply port 1c, and the first control valve 6 is arranged on the connecting passage between the inlet 1a and the air supply port 1c.

[0075] Among them, the refrigerant circulation system has a first heating mode. In the first heating mode, the first control valve 6 is opened, the air supply port 1c, the first control valve 6 and the inlet 1a are connected in sequence to form a first self-circulation passage, and the refrigerant in the refrigerant circulation system circulates in the first self-circulation passage to increase the internal temperature of the compressor 1.

[0076] In the above embodiment, by setting up the first self-circulation passage, the indoor unit can remain in the non-operating state, and the heating function of the compressor can be realized through part of the pipeline of the outdoor unit. The internal temperature of the compressor is effectively increased, and the liquid refrigerant retained in the outdoor heat exchanger and other components can be quickly driven to flow. In this way, when the outdoor temperature is low, the user is accustomed to shutting down the machine at night, or the refrigerant circulation system is left unused for a long time, the time it takes for the refrigerant circulation system to start heating can be shortened. This is also beneficial to protecting the compressor and increasing the service life of the compressor.

[0077] In some embodiments, the refrigerant circulation system further includes a first expansion valve 5, which is disposed on the connection passage between the air supply port 1c and the first control valve 6. The first expansion valve 5 can be used to change the state of the refrigerant in the first self-circulation passage.

[0078] In some embodiments, the refrigerant circulation system further includes a gas-liquid separator 9, the outlet of the gas-liquid separator 9 is connected to the inlet 1a of the compressor 1. In the first self-circulation path, the gas replenishment port 1c, the first expansion valve 5, the first control valve 6, the gas-liquid separator 9 and the inlet 1a are connected in sequence.

[0079] In some embodiments, the refrigerant circulation system also includes an outdoor heat exchanger 3 and a gas-liquid separator 9, and the compressor also includes an outlet 1b. In the first heating mode, the outlet 1b, the outdoor heat exchanger 3, the first control valve 6, the gas-liquid separator 9 and the inlet 1a are connected in sequence to form a second self-circulation passage.

[0080] By providing the second self-circulation passage, the flow rate for heating the compressor 1 can be increased, thereby improving the temperature rise speed of the compressor 1.

[0081] In some embodiments, the refrigerant circulation system further includes an indoor heat exchanger 2 and a subcooler 4. The subcooler 4 is connected between the indoor heat exchanger 2 and the outdoor heat exchanger 3, and the subcooler 4 is connected to the air supply port 1c and the inlet 1a of the compressor 1 respectively.

[0082] In some embodiments, the refrigerant circulation system further includes a second expansion valve 7 , which is disposed on a connecting passage between the subcooler 4 and the indoor heat exchanger 2 .

[0083] In some embodiments, the refrigerant circulation system also includes a power supply, the compressor 1 includes a rotor and a stator, and the refrigerant circulation system has a second heating mode. In the second heating mode, the power supply is electrically connected to the stator, and the windings of the stator are energized and dissipate heat to increase the internal temperature of the compressor 1.

[0084] By providing a power supply, the stator winding can be energized when the rotor is stationary, so that the stator winding emits heat to heat the compressor 1.

[0085] In some embodiments, the refrigerant circulation system further includes a control device 11, which is connected to the first control valve 6 and a power supply signal, and is used to adjust the refrigerant circulation system to the first heating mode or the second heating mode.

[0086] In some embodiments, the refrigerant circulation system also includes a heating belt, which is wrapped around the outer circumference of the part to be heated of the refrigerant circulation system. The refrigerant circulation system has a third heating mode. In the third heating mode, the heating belt is started to heat the part to be heated through the heating belt.

[0087] By providing a heating belt, the portion to be heated can be heated, thereby increasing the internal temperature of the compressor.

[0088] In some embodiments, the part to be heated includes the bottom of the compressor 1; alternatively, the refrigerant circulation system further includes an oil-gas separator 10 connected to the outlet 1b, and the part to be heated includes the bottom of the oil-gas separator 10; alternatively, the refrigerant circulation system further includes a gas-liquid separator 9 connected to the inlet 1a, and the part to be heated includes the bottom of the gas-liquid separator 9.

[0089] like Figure 1 As shown, the heating belt includes a first heating belt 81, a second heating belt 82 and a third heating belt 83. The first heating belt 81 is wrapped around the bottom periphery of the compressor 1, the second heating belt 82 is wrapped around the bottom periphery of the gas-liquid separator 9, and the third heating belt 83 is wrapped around the bottom periphery of the oil-gas separator 10.

[0090] The first heating belt 81 can directly heat the compressor 1, increase the internal temperature of the compressor 1, accelerate the gasification of the liquid refrigerant in the compressor 1, and increase the heating speed of the refrigerant circulation system. The second heating belt 82 can heat the bottom of the gas-liquid separator 9, which is conducive to accelerating the flow of the refrigerant remaining in the gas-liquid separator 9, thereby accelerating the flow of the refrigerant in the compressor 1 and increasing the internal temperature of the compressor 1. The third heating belt 83 can heat the bottom of the oil-gas separator 10, which is conducive to accelerating the flow of the refrigerant remaining in the oil-gas separator 10, thereby accelerating the flow of the refrigerant in the compressor 1 and increasing the internal temperature of the compressor 1.

[0091] In some embodiments, the refrigerant circulation system also includes a control device 11, which is connected to the first expansion valve 5, the first control valve 6, the second expansion valve 7 and the heating belt signal, and the control device 11 is used to adjust the refrigerant circulation system to the first heating mode or the third heating mode.

[0092] In some embodiments, the refrigerant circulation system also includes a control device 11 and a heating belt, which is wrapped around the periphery of the part to be heated of the refrigerant circulation system. The refrigerant circulation system has a third heating mode. In the third heating mode, the heating belt is started to heat the part to be heated through the heating belt. The control device 11 is connected to the first control valve 6, the power supply and the heating belt signal. The control device 11 is used to adjust the refrigerant circulation system to the first heating mode, the second heating mode or the third heating mode.

[0093] In some embodiments, the first heating mode and the third heating mode can be turned on at the same time, or the second heating mode and the third heating mode can be turned on at the same time. Although the first heating mode and the second heating mode cannot be used at the same time, they can be used at intervals. The two modes are used to heat the compressor 1 at the same time, thereby effectively improving the heating efficiency and more effectively shortening the time for the refrigerant circulation system to start heating.

[0094] Based on the refrigerant circulation system in each of the above embodiments, the present invention further provides an air-conditioning unit, which includes the above refrigerant circulation system.

[0095] Based on the refrigerant circulation system in each of the above embodiments, the present invention further provides a control method for the refrigerant circulation system, including:

[0096] Detecting the internal temperature of the compressor 1;

[0097] According to the internal temperature of the compressor 1, a heating mode is selected;

[0098] When the selected heating mode is the first heating mode, open the first control valve 6, so that the air supply port 1c, the first expansion valve 5, the first control valve 6 and the inlet 1a are connected in sequence to form a first self-circulation passage, and the refrigerant in the refrigerant circulation system circulates in the first self-circulation passage.

[0099] In some embodiments, the control method further comprises:

[0100] Providing a power supply, the compressor 1 includes a rotor and a stator;

[0101] When the selected heating mode is the second heating mode, the power supply is electrically connected to the stator, the winding of the stator is energized and dissipates heat to increase the internal temperature of the compressor 1 .

[0102] In some embodiments, the control method further comprises:

[0103] Providing a heating belt, the heating belt is wrapped around the outer periphery of the part to be heated of the refrigerant circulation system;

[0104] When the selected heating mode is the third heating mode, the heating belt is started to heat the portion to be heated.

[0105] In some embodiments, according to the internal temperature of the compressor 1, the operation of selecting the heating mode includes:

[0106] Determining whether the internal temperature of the compressor 1 meets a first preset condition;

[0107] When the internal temperature of the compressor 1 meets the first preset condition, the second heating mode and the third heating mode are started;

[0108] If the first preset condition is not met, then continue to determine whether the internal temperature of the compressor 1 meets the second preset condition;

[0109] If the second preset condition is met, the first heating mode and the third heating mode are activated.

[0110] In some embodiments, the first preset condition includes: within a continuous period of time t2, the internal temperature of the compressor 1 is greater than or equal to T2 and less than T1; the second preset condition includes: within a continuous period of time t3, the internal temperature of the compressor 1 is less than T2, wherein t1 <t2<t3,T1> T2.

[0111] In some embodiments, before determining whether the internal temperature of the compressor 1 satisfies the first preset condition, the operation of selecting the heating mode according to the internal temperature of the compressor 1 further includes:

[0112] Determining whether the refrigerant circulation system meets the third preset condition;

[0113] When the refrigerant circulation system meets the third preset condition, the preheating function is started;

[0114] After the preheating function is turned on, it is determined whether the internal temperature of the compressor 1 meets the fourth preset condition;

[0115] If the internal temperature of the compressor 1 meets the fourth preset condition, no heating mode is started; if the internal temperature of the compressor 1 does not meet the fourth preset condition, the step of determining whether the internal temperature of the compressor 1 meets the first preset condition is entered.

[0116] In some embodiments, the refrigerant circulation system includes a photovoltaic power generation device 12 that provides electricity, and the third preset condition includes: the refrigerant circulation system is powered on for the first time or has been powered on and the standby time exceeds t0, and the power generation voltage of the photovoltaic power generation device 12 is not less than the preset voltage value; the fourth preset condition includes: within a continuous time of t1, the internal temperature of the compressor 1 is not less than T1.

[0117] In some embodiments, the preset voltage value may be 90% of the voltage required when the first heating mode, the second heating mode, or the third heating mode is started.

[0118] In some embodiments, according to the internal temperature of the compressor 1, the operation of selecting the heating mode further includes:

[0119] After starting the first heating mode and the third heating mode, determining whether the internal temperature of the compressor 1 satisfies a fifth preset condition;

[0120] When the internal temperature of the compressor 1 satisfies the fifth preset condition, the preheating function is turned off.

[0121] In some embodiments, the fifth preset condition includes:

[0122] When the operation time of the first heating mode and the third heating mode reaches t4, the difference between the internal temperature of the compressor 1 and the outdoor ambient temperature is greater than T3; or

[0123] During the continuous time t4, the internal temperature of the compressor 1 is not less than T4.

[0124] In some embodiments, in the second heating mode, the control method further includes:

[0125] When the refrigerant circulation system is in standby mode, the heating demand of the indoor unit is zero, and the continuous downtime of the compressor 1 is less than t5, the electrical connection between the power supply and the stator is disconnected;

[0126] When the refrigerant circulation system is in standby mode, the internal temperature of the compressor 1 is greater than or equal to T5 and less than T6 for a continuous period of time t6, and when the compressor 1 is powered on for the first time or has been powered on and the standby time exceeds t7, the power supply is electrically connected to the stator.

[0127] In some embodiments, in the second heating mode, the control method further includes:

[0128] After starting the second heating mode, before measuring the internal temperature of the compressor 1 or when the difference between the internal temperature of the compressor 1 and the outdoor ambient temperature is not greater than T7, the current of the stator winding satisfies: A1 = a*T0 2 +b*T0+c, where T0 is the outdoor ambient temperature, and a, b and c are all constants;

[0129] When the difference between the internal temperature of the compressor 1 and the outdoor ambient temperature is greater than T7, the current through the stator winding satisfies: A2=A0*(1+d), where A0 is the current current, d is the periodic change of the internal temperature of the compressor 1, and d is a constant.

[0130] In various embodiments provided by the present invention, the internal temperature of the compressor 1 may be the top temperature of the compressor 1 . The top of the compressor 1 may more accurately reflect the actual temperature inside the compressor 1 and is easy to measure.

[0131] The following is combined with Figure 1 and 2 The working process of an embodiment of the refrigerant circulation system and the air conditioning unit of the present invention is described as follows:

[0132] like Figure 1 As shown, the outdoor unit includes a compressor 1, an outdoor heat exchanger 3, a subcooler 4, a first expansion valve 5, a first control valve 6, a gas-liquid separator 9, an oil-gas separator 10, a four-way valve 14, a third expansion valve 15 and a fourth expansion valve 16. The indoor unit includes a plurality of indoor heat exchangers 2 and a plurality of corresponding second expansion valves 7. The bottom periphery of the compressor 1 is wrapped with a first heating belt 81. The bottom periphery of the gas-liquid separator 9 is wrapped with a second heating belt 82. The bottom periphery of the oil-gas separator 10 is wrapped with a third heating belt 83. A second control valve 17 and a third control valve 18 are provided on the connecting pipeline between the indoor unit and the outdoor unit.

[0133] The air conditioning unit further includes a control device 11, a photovoltaic power generation device 12 and a load 13. The photovoltaic power generation device 12 can provide power for the air conditioning unit. The load 13 can be a component connected to the control device 11 by signal, and the control device 11 can electrically control these components. For example, the load 13 can be a first expansion valve 5, a second expansion valve 7, a third expansion valve 15, a fourth expansion valve 16, a first control valve 6, a second control valve 17, a third control valve 18, a first heating belt 81, a second heating belt 82, and a third heating belt 83, etc.

[0134] In this embodiment, the compressor 1 is an enthalpy injection scroll compressor, and a medium-pressure enthalpy injection port is provided in the middle position of its static scroll. Through the air inlet 1c, a portion of the intermediate-pressure gas can be sucked in, mixed with the partially compressed refrigerant and then compressed, so that two-stage compression can be achieved with a single compressor, which increases the refrigerant flow in the condenser and the enthalpy difference of the main circulation loop, thereby greatly improving the efficiency of the compressor.

[0135] The stator winding of the compressor can also be passed through an excitation current, that is, when the rotor is not rotating, the stator winding is energized to generate electromagnetic heat in the stator to heat the internal temperature of the compressor.

[0136] When the stator heating and the heating belt generate heat slowly, the compressor 1 can be started, and the internal refrigerant circulation can be realized through the first self-circulation passage and the second self-circulation passage to generate heat, thereby heating the compressor 1.

[0137] like Figure 1As shown, when the first heating mode is turned on, the first expansion valve 5 is opened to the maximum opening; the first control valve 6 is in the power-on state, that is, the open state; the four-way valve 14 is in the power-off state, that is, the closed state; the third expansion valve 15 and the fourth expansion valve 16 are opened to the maximum opening; the opening of the second expansion valve 7 is opened to zero. The compressor 1 can be operated at H1 by default. When the detected temperature of the high-pressure sensor of the compressor 1 is not less than X1 or the detected temperature of the low-pressure sensor is not greater than X2 for a continuous period of time, the operating frequency of the compressor 1 is reduced by △H each time, but the minimum operating frequency is not lower than H1.

[0138] The path of the first self-circulating path is:

[0139] It is ejected from the air supply inlet 1c of the compressor 1 to the first expansion valve 5, to the first control valve 6, to the gas-liquid separator 9, and finally to the air intake port of the compressor 1.

[0140] The path of the second self-circulating path is:

[0141] It is ejected from the exhaust port of the compressor, to the four-way valve 14, to the outdoor heat exchanger 3, to the fourth expansion valve 16, through the cooler 4 to the first control valve 6, to the gas-liquid separator 9, and finally to the suction port of the compressor 1.

[0142] When controlling the air conditioning unit, the first heating mode, the second heating mode or the third heating mode can be used alone, or a combination mode of the first heating mode, the second heating mode and the third heating mode can be used, and the combination mode includes a combination of the first heating mode and the second heating mode, a combination of the first heating mode and the third heating mode, a combination of the second heating mode and the third heating mode, and a combination of the first heating mode, the second heating mode and the third heating mode. Among them, the first heating mode and the third heating mode can be turned on at the same time, the second heating mode and the third heating mode can also be turned on at the same time, and although the first heating mode and the second heating mode cannot be turned on at the same time, they can be turned on at intervals.

[0143] For example, in one embodiment, the second heating mode and the third heating mode can be started at the same time, so that the heating efficiency can be effectively improved by heating with dual heat sources, and the refrigerant retained at the bottom of the compressor 1 can be heated and precipitated from the oil; then, within the default time, if the heating effect is not obvious, the second heating mode can be turned off and the first heating mode can be started. The heat generated by the self-circulation heating of the compressor is higher than the stator heating. At this time, the heating temperature can be further increased by heating with dual heat sources of the first heating mode and the third heating mode. The principle of compressor self-circulation heating is consistent with the principle of steam compression refrigeration, that is, part of the condensation heat is generated by the power consumption of the motor, and the other part is generated by compressing the gas.

[0144] The working process of this embodiment is described below:

[0145] refer to Figure 2 As shown, when the air conditioning unit is powered on for the first time or has been powered on and the standby time exceeds t0, and the power generation voltage of the photovoltaic power generation device 12 is not less than 90% of the voltage required when the first heating mode, the second heating mode or the third heating mode is started, the preheating function is started;

[0146] After the preheating function is turned on:

[0147] 1. If the top temperature of compressor 1 is not less than T1 within a continuous period of t1, no heating mode will be started;

[0148] 2. If the top temperature of compressor 1 is greater than or equal to T2 and less than T1 within a continuous period of t2, the second heating mode and the third heating mode are started simultaneously;

[0149] 3. If the top temperature of the compressor 1 is less than T2 for a continuous period of time t3, the first heating mode and the third heating mode are started simultaneously.

[0150] When the air conditioner meets any of the following two conditions, the preheating function is turned off:

[0151] 1 When the working time of the first heating mode and the third heating mode reaches t4, the difference between the top temperature of the compressor 1 and the outdoor ambient temperature is greater than T3;

[0152] 2 During the continuous time t4, the top temperature of compressor 1 is not less than T4.

[0153] Among them, Figure 3 As shown, the control principle of the second heating mode is:

[0154] After entering the control process of the second heating mode, when the air-conditioning unit is in standby mode, the heating demand of the indoor unit is zero, and the continuous shutdown time of the compressor 1 is less than t5, the electrical connection between the power supply and the stator is disconnected, that is, the second heating mode is in the off state;

[0155] When the air-conditioning unit is in standby mode, the top temperature of compressor 1 is greater than or equal to T5 and less than T6 for a continuous period of t6, and when compressor 1 is powered on for the first time or has been powered on and the standby time exceeds t7, the power supply is electrically connected to the stator to start the second heating mode.

[0156] After starting the second heating mode, before measuring the internal temperature of the compressor 1 or when the difference between the top temperature of the compressor 1 and the outdoor ambient temperature is not greater than T7, the current of the stator winding satisfies: A1 = a*T0 2 +b*T0+c, where T0 is the outdoor ambient temperature, a, b and c are all constants, for example, a=0.03, b=0.07, c=15;

[0157] When the difference between the top temperature of compressor 1 and the outdoor ambient temperature is greater than T7, the current through the stator winding satisfies: A2=A0*(1+d), where A0 is the current current, d is the periodic change of the internal temperature of compressor 1, and d is a constant, such as d=0.1.

[0158] Through the description of multiple embodiments of the refrigerant circulation system and its control method, and the air-conditioning unit of the present invention, it can be seen that the refrigerant circulation system and its control method, and the air-conditioning unit embodiments of the present invention have added a compressor preheating control function, which can effectively improve the reliability and service life of the compressor.

[0159] The air conditioning unit provided by the present invention can be a multi-split unit, such as a photovoltaic multi-split unit, or a unit of other structures. Since photovoltaic electricity comes from solar energy, the photovoltaic multi-split unit can use photovoltaic electricity to maintain its own operation and realize the preheating function without consuming the power of the power grid. By using the preheating function of the photovoltaic multi-split unit itself, the reliability of the whole machine can be improved, the service life of the compressor can be extended, and the time to achieve the heating effect at low temperature can be accelerated.

[0160] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that without departing from the principles of the present invention, the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents, and these modifications and equivalent replacements should be included in the scope of the technical solution for protection of the present invention.

Claims

1. A refrigerant circulation system, characterized in that: include: The compressor (1) comprises an inlet (1a) and an air supply port (1c), wherein the air supply port (1c) is used to inhale a refrigerant at an intermediate pressure; and A first control valve (6) is arranged on a connecting passage between the inlet (1a) and the air supply port (1c); The refrigerant circulation system has a first heating mode. In the first heating mode, the first control valve (6) is opened, the air supply port (1c), the first control valve (6) and the inlet (1a) are connected in sequence to form a first self-circulating passage, and the flow path of the refrigerant is to be ejected from the air supply port (1c), to the first control valve (6), and finally to the inlet (1a).

2. The refrigerant circulation system according to claim 1, characterized in that: It also includes a first expansion valve (5) arranged between the air supply port (1c) and the first control valve (6).

3. The refrigerant circulation system according to claim 1, characterized in that: The compressor (1) further comprises an outdoor heat exchanger (3) and a gas-liquid separator (9); the compressor (1) further comprises an outlet (1b); in the first heating mode, the outlet (1b), the outdoor heat exchanger (3), the first control valve (6), the gas-liquid separator (9) and the inlet (1a) are connected in sequence to form a second self-circulating passage.

4. The refrigerant circulation system according to any one of claims 1 to 3, characterized in that: It also includes a power supply, the compressor (1) includes a rotor and a stator, and the refrigerant circulation system has a second heating mode. In the second heating mode, the power supply is electrically connected to the stator so that the winding of the stator is energized and dissipates heat.

5. The refrigerant circulation system according to claim 4, characterized in that: It also includes a control device (11), the control device (11) being connected to the first control valve (6) and the power supply signal, and the control device (11) being used to adjust the refrigerant circulation system to the first heating mode or the second heating mode.

6. The refrigerant circulation system according to claim 1, characterized in that: It also includes a heating belt, which is wrapped around the outer circumference of the part to be heated of the refrigerant circulation system. The refrigerant circulation system has a third heating mode. In the third heating mode, the heating belt is started to heat the part to be heated through the heating belt.

7. The refrigerant circulation system according to claim 6, characterized in that: The portion to be heated includes the bottom of the compressor (1); or, the refrigerant circulation system further includes an oil-gas separator (10) connected to the outlet (1b) of the compressor (1), and the portion to be heated includes the bottom of the oil-gas separator (10); or, the refrigerant circulation system further includes a gas-liquid separator (9) connected to the inlet (1a), and the portion to be heated includes the bottom of the gas-liquid separator (9).

8. The refrigerant circulation system according to claim 6, characterized in that: It also comprises a control device (11), the control device (11) being connected to the first control valve (6) and the heating belt signal, the control device (11) being used to adjust the refrigerant circulation system to the first heating mode or the third heating mode.

9. The refrigerant circulation system according to claim 4, characterized in that: It also includes a control device (11) and a heating belt, wherein the heating belt is wrapped around the outer circumference of the part to be heated of the refrigerant circulation system, and the refrigerant circulation system has a third heating mode. In the third heating mode, the heating belt is started to heat the part to be heated through the heating belt. The control device (11) is connected to the first control valve (6), the power supply and the heating belt signal, and the control device (11) is used to adjust the refrigerant circulation system to the first heating mode, the second heating mode or the third heating mode.

10. An air conditioning unit, characterized in that: A refrigerant circulation system comprising the refrigerant circulation system as claimed in any one of claims 1 to 9.

11. A control method based on the refrigerant circulation system according to any one of claims 1 to 9, characterized in that: include: Detecting the internal temperature of the compressor (1); Selecting a heating mode according to the internal temperature of the compressor (1); When the selected heating mode is the first heating mode, the first control valve (6) is opened, so that the air supply port (1c), the first control valve (6) and the inlet (1a) are connected in sequence to form a first self-circulating passage, and the refrigerant in the refrigerant circulation system circulates in the first self-circulating passage.

12. The control method of the refrigerant circulation system according to claim 11, characterized in that: Also includes: Providing a power supply, the compressor (1) comprises a rotor and a stator; When the selected heating mode is the second heating mode, the power supply is connected to the stator, the winding of the stator is energized and dissipates heat to increase the internal temperature of the compressor (1).

13. The control method of the refrigerant circulation system according to claim 12, characterized in that: Also includes: Providing a heating belt, wherein the heating belt is wrapped around the periphery of the part to be heated of the refrigerant circulation system; When the selected heating mode is the third heating mode, the heating belt is started to heat the part to be heated by the heating belt.

14. The control method of the refrigerant circulation system according to claim 13, characterized in that: According to the internal temperature of the compressor (1), the operation of selecting the heating mode comprises: Determining whether the internal temperature of the compressor (1) satisfies a first preset condition; When the internal temperature of the compressor (1) satisfies a first preset condition, the second heating mode and the third heating mode are activated simultaneously; If the first preset condition is not met, continuing to determine whether the internal temperature of the compressor (1) meets a second preset condition; If the second preset condition is met, the first heating mode and the third heating mode are started.

15. The control method of the refrigerant circulation system according to claim 14, characterized in that: The first preset condition includes: within a continuous period of time t2, the internal temperature of the compressor (1) is greater than or equal to T2 and less than T1; the second preset condition includes: within a continuous period of time t3, the internal temperature of the compressor (1) is less than T2, wherein t1 <t2<t3,T1> T2.

16. The control method of the refrigerant circulation system according to claim 14, characterized in that: Before determining whether the internal temperature of the compressor (1) satisfies the first preset condition, the operation of selecting the heating mode according to the internal temperature of the compressor (1) further includes: Determining whether the refrigerant circulation system meets a third preset condition; When the refrigerant circulation system meets the third preset condition, starting the preheating function; After the preheating function is turned on, determining whether the internal temperature of the compressor (1) satisfies a fourth preset condition; If the internal temperature of the compressor (1) satisfies the fourth preset condition, no heating mode is activated; if the internal temperature of the compressor (1) does not satisfy the fourth preset condition, the step of determining whether the internal temperature of the compressor (1) satisfies the first preset condition is entered.

17. The control method of the refrigerant circulation system according to claim 16, characterized in that: The refrigerant circulation system includes a photovoltaic power generation device (12) for providing electric power, the third preset condition includes: the refrigerant circulation system is powered on for the first time or has been powered on and the standby time exceeds t0, and the power generation voltage of the photovoltaic power generation device (12) is not less than a preset voltage value; the fourth preset condition includes: within a continuous time of t1, the internal temperature of the compressor (1) is not less than T1.

18. The control method of the refrigerant circulation system according to claim 16, characterized in that: According to the internal temperature of the compressor (1), the operation of selecting the heating mode further comprises: After starting the first heating mode and the third heating mode, determining whether the internal temperature of the compressor (1) satisfies a fifth preset condition; When the internal temperature of the compressor (1) satisfies a fifth preset condition, the preheating function is turned off.

19. The control method of the refrigerant circulation system according to claim 18, characterized in that: The fifth preset condition includes: When the operation time of the first heating mode and the third heating mode reaches t4, the difference between the internal temperature of the compressor (1) and the outdoor ambient temperature is greater than T3; or During the continuous time t4, the internal temperature of the compressor (1) is not less than T4.

20. The control method of the refrigerant circulation system according to any one of claims 12 to 19, characterized in that: In the second heating mode, the method further includes: When the refrigerant circulation system is in a standby state, the heating demand of the indoor unit is zero, and the continuous downtime of the compressor (1) is less than t5, the electrical connection between the power supply and the stator is disconnected; When the refrigerant circulation system is in a standby state, the internal temperature of the compressor (1) is greater than or equal to T5 and less than T6 for a continuous period of time t6, and when the compressor (1) is powered on for the first time or has been powered on and the standby time exceeds t7, the power supply is electrically connected to the stator.

21. The control method of a refrigerant circulation system according to any one of claims 12 to 19, characterized in that: In the second heating mode, the method further includes: After starting the second heating mode, before measuring the internal temperature of the compressor (1) or when the difference between the internal temperature of the compressor (1) and the outdoor ambient temperature is not greater than T7, the current of the stator winding satisfies: A1=a*T0 2 +b*T0+c, where T0 is the outdoor ambient temperature, and a, b and c are all constants; When the difference between the internal temperature of the compressor (1) and the outdoor ambient temperature is greater than T7, the current of the stator winding satisfies: A2=A0*(1+d), wherein A0 is the current current, d is the periodic change of the internal temperature of the compressor (1), and d is a constant.

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