Refrigeration method, defrosting method, controller and air conditioning system thereof

Abstract

The invention discloses a refrigeration method, a defrosting method, a controller and an air conditioning system.The refrigeration method comprises the steps that in a refrigeration mode, a refrigerant sequentially passes through an expansion valve, a refrigerant heat dissipation assembly and a one-way throttle valve, so that the refrigerant throttled by the expansion valve passes through the refrigerant heat dissipation assembly and then reaches the one-way throttle valve; the refrigerant temperature in the refrigerant heat dissipation assembly can be lower, the current limit value of the main control board can be improved, the maximum operation frequency of the compressor can be improved in combination with opening control of the expansion valve, high-temperature refrigeration with better performance is achieved, and the applicable temperature range of the high-temperature refrigeration is widened. According to the defrosting method, the opening degree of an expansion valve is increased after the rotating speed of an indoor fan is reduced and the operation frequency of a compressor is reduced, the temperature of a liquid refrigerant staying in an indoor heat exchanger is increased, and the liquid refrigerant is rapidly transferred to an outdoor heat exchanger, so that the outdoor heat exchanger is defrosted; and meanwhile, the problem that the indoor heat exchanger generates refrigerant sound after entering the defrosting mode is solved.

Description

Technical Field

[0001] The present application relates to the technical field of air conditioner applications, and in particular to a refrigeration method, a defrosting method, a controller and an air conditioning system thereof. Background Art

[0002] As the outdoor ambient temperature continues to rise, the cooling load of the air-conditioning system increases, and the operating frequency of the compressor and the speed of the fan need to be further increased. The current flowing through the main control board becomes larger, thus placing higher requirements on the heat dissipation of the main control board.

[0003] At present, some air conditioning systems lead a short refrigerant pipe to the main control board in the refrigerant circulation system, and use the refrigerant flowing through the short refrigerant pipe to cool the electrical components on the main control board. In the cooling mode, the one-way throttle valve is located upstream of the short refrigerant pipe and the direction of the one-way throttle valve is opposite to the flow direction of the refrigerant. Due to the restriction of the one-way throttle valve, the flow rate of the refrigerant entering the short refrigerant pipe is reduced, which is not conducive to high-temperature cooling and heating defrosting of the air conditioning system. Summary of the invention

[0004] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a refrigeration method, a defrosting method, a controller and an air conditioning system thereof, which can improve the efficiency and effect of refrigeration and defrosting.

[0005] An embodiment of the first aspect of the present application provides a refrigeration method, which is applied to an air-conditioning system, wherein the air-conditioning system comprises an outdoor heat exchanger, an indoor heat exchanger, an expansion valve, a refrigerant heat dissipation component and a one-way throttle valve, wherein the outdoor heat exchanger, the expansion valve, the refrigerant heat dissipation component, the one-way throttle valve and the indoor heat exchanger are connected in sequence, the direction of the one-way throttle valve points to the indoor heat exchanger, and the refrigerant heat dissipation component is used to perform heat exchange with a main control board of the air-conditioning system; the refrigeration method comprises:

[0006] When the outdoor ambient temperature is in a first temperature range and the current operating frequency of the compressor of the air-conditioning system is lower than a first operating frequency, reducing the opening of the expansion valve to reduce the temperature of the refrigerant in the refrigerant heat dissipation component, the first operating frequency being determined according to the target operating frequency of the compressor and a first adjustment value;

[0007] Increasing the current limiting value of the main control board according to the temperature of the refrigerant in the refrigerant heat dissipation component, and increasing the current operating frequency of the compressor according to the current limiting value;

[0008] When the current operating frequency of the compressor is lower than the target operating frequency, the opening of the expansion valve is reduced again to increase the current operating frequency of the compressor again.

[0009] The refrigeration method of the first aspect embodiment of the present application has at least the following beneficial effects: in the refrigeration mode, the refrigerant passes through the expansion valve, the refrigerant heat dissipation component and the one-way throttle valve in sequence, so that the refrigerant after throttling by the expansion valve first passes through the refrigerant heat dissipation component and then reaches the one-way throttle valve. The refrigerant temperature in the refrigerant heat dissipation component can be lower, which helps the main control board to increase the current limit. Combined with the opening control of the expansion valve, it can increase the maximum operating frequency of the compressor, achieve better high-temperature refrigeration performance and broaden the applicable temperature range of high-temperature refrigeration.

[0010] According to some embodiments of the present application, reducing the opening of the expansion valve includes:

[0011] The opening of the expansion valve is reduced according to a preset opening value.

[0012] According to some embodiments of the present application, after reducing the opening of the expansion valve according to a preset opening value, the refrigeration method further includes:

[0013] Obtaining the evaporation temperature of the indoor heat exchanger;

[0014] When the evaporating temperature of the indoor heat exchanger is lower than a preset evaporating temperature, the current opening of the expansion valve is locked and the current operating frequency of the compressor is maintained. The preset evaporating temperature is determined according to the maximum evaporating temperature and the protection margin temperature corresponding to the first temperature range.

[0015] According to some embodiments of the present application, the refrigeration method includes:

[0016] When the outdoor ambient temperature is in the first temperature range and the current operating frequency of the compressor is higher than the first operating frequency, or when the outdoor ambient temperature is in the second temperature range or the third temperature range, adjusting the opening of the expansion valve according to the opening range corresponding to the current temperature range and the exhaust superheat of the compressor;

[0017] The lower limit temperature of the first temperature interval is greater than the upper limit temperature of the second temperature interval, and the lower limit temperature of the second temperature interval is greater than the upper limit temperature of the third temperature interval.

[0018] According to some embodiments of the present application, the step of adjusting the opening of the expansion valve according to the opening range corresponding to the current temperature interval and the exhaust superheat of the compressor comprises:

[0019] determining an initial opening degree of the expansion valve according to the outdoor ambient temperature and the target operating frequency of the compressor;

[0020] Adjusting the initial opening of the expansion valve according to the exhaust superheat of the compressor and the superheat control coefficient corresponding to the current temperature range, and controlling the opening of the expansion valve not to exceed the opening range corresponding to the current temperature range;

[0021] Wherein, the superheat control coefficient is determined according to the exhaust temperature of the compressor.

[0022] A second aspect of the present application provides a defrosting method, which is applied to an air-conditioning system, wherein the air-conditioning system includes an outdoor heat exchanger, an indoor heat exchanger, an expansion valve, a refrigerant heat dissipation component, and a one-way throttle valve, wherein the outdoor heat exchanger, the expansion valve, the refrigerant heat dissipation component, the one-way throttle valve, and the indoor heat exchanger are connected in sequence, the direction of the one-way throttle valve points to the indoor heat exchanger, and the refrigerant heat dissipation component is used to perform heat exchange with a main control board of the air-conditioning system; the defrosting method includes:

[0023] Before entering the defrost mode, reducing the speed of the indoor fan of the air conditioning system;

[0024] The opening of the expansion valve is increased after the operating frequency of the compressor of the air conditioning system is reduced.

[0025] The defrosting method of the second aspect embodiment of the present application has at least the following beneficial effects: before the air-conditioning system enters the defrost mode, the indoor fan, compressor and expansion valve are adjusted, and the opening of the expansion valve is increased by reducing the speed of the indoor fan and the operating frequency of the compressor, thereby increasing the temperature of the liquid refrigerant remaining in the indoor heat exchanger and quickly transferring the liquid refrigerant to the outdoor heat exchanger, thereby defrosting the outdoor heat exchanger. The method of this embodiment is suitable for quickly melting thin frost on the outdoor heat exchanger, and completes the defrosting operation of the outdoor heat exchanger without basically affecting the indoor heating. At the same time, it solves the problem of refrigerant sound appearing in the indoor heat exchanger after entering the defrost mode.

[0026] According to some embodiments of the present application, the step of increasing the opening of the expansion valve after reducing the operating frequency of the compressor of the air-conditioning system includes:

[0027] Obtaining the coil temperature of the outdoor heat exchanger;

[0028] When the coil temperature is greater than a first temperature value, at a first moment before entering a defrost mode, reducing the operating frequency of the compressor of the air conditioning system;

[0029] When the operating frequency of the compressor of the air-conditioning system decreases to the second operating frequency, the opening degree of the expansion valve is increased and the opening degree of the expansion valve is increased to the first opening degree when entering the defrost mode.

[0030] According to some embodiments of the present application, the step of increasing the opening of the expansion valve after reducing the operating frequency of the compressor of the air-conditioning system includes:

[0031] Obtaining the coil temperature of the outdoor heat exchanger;

[0032] When the coil temperature is less than the first temperature value and greater than a second temperature value, at a second moment before entering the defrost mode, the operating frequency of the compressor is reduced and the opening of the expansion valve is increased, and the second moment is earlier than the first moment;

[0033] When the operating frequency of the compressor drops to the third operating frequency and the opening of the expansion valve increases to the second opening, the current operating frequency of the compressor and the current opening of the expansion valve are maintained until entering the defrosting mode.

[0034] According to some embodiments of the present application, the defrosting method further includes:

[0035] After entering the defrost mode, shutting down the outdoor fan of the air conditioning system;

[0036] The operating frequency of the compressor is controlled to drop to a fourth operating frequency.

[0037] According to some embodiments of the present application, the defrosting method further includes:

[0038] After entering the defrost mode, the outdoor fan of the air conditioning system is turned off, and the speed of the indoor fan is reduced to 0 within a preset time;

[0039] controlling the operating frequency of the compressor to drop to a fifth operating frequency;

[0040] The opening degree of the expansion valve is controlled to increase to a third opening degree and then to a fourth opening degree.

[0041] According to some embodiments of the present application, the air-conditioning system further includes a four-way valve; before and after entering the defrost mode, the valve state of the four-way valve does not change.

[0042] The third aspect of the present application provides a controller, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the above-mentioned refrigeration method or the above-mentioned defrosting method when running the computer program.

[0043] A fourth aspect of the present application provides an air-conditioning system, comprising a controller as described above.

[0044] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or understood by practicing the present application. The purpose and other advantages of the present application can be realized and obtained by the structures specifically pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a structural schematic diagram of an air conditioning system in the related art;

[0046] Figure 2 is a structural schematic diagram of an air conditioning system provided in an embodiment of the present application;

[0047] Figure 3 is a flow chart of a refrigeration method provided in an embodiment of the present application;

[0048] Figure 4 This is a flow chart after reducing the opening of the expansion valve according to an embodiment of the present application;

[0049] Figure 5 is a flow chart of adjusting the opening of an expansion valve provided in an embodiment of the present application;

[0050] Figure 6 is a flowchart of a specific example of a refrigeration method provided in an embodiment of the present application;

[0051] Figure 7 is a flow chart of a defrosting method provided in an embodiment of the present application;

[0052] Figure 8 is a timing diagram of the defrost mode A provided in an embodiment of the present application;

[0053] Fig. 9 is a timing diagram of the defrost mode B provided in an embodiment of the present application;

[0054] Fig.10 is a flow chart a for increasing the opening of the expansion valve provided in an embodiment of the present application;

[0055] Fig.11 is a flow chart b for increasing the opening of the expansion valve provided in an embodiment of the present application;

[0056] Fig.12 This is a flow chart a after entering the defrost mode provided by an embodiment of the present application;

[0057] Fig.13 This is a flow chart b after entering the defrost mode provided in an embodiment of the present application;

[0058] Fig.14 is a flowchart a of a specific example of a defrosting method provided in an embodiment of the present application;

[0059] Fig.15 It is a flowchart b of a specific example of the defrosting method provided in an embodiment of the present application.

[0060] Reference numerals:

[0061] Outdoor heat exchanger 100,

[0062] Indoor heat exchanger 200,

[0063] Expansion valve 300,

[0064] Refrigerant short pipe 400,

[0065] One-way throttle valve 500,

[0066] Four-way valve 600,

[0067] Compressor 700. DETAILED DESCRIPTION

[0068] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. In addition, the characteristics, operations or features described in the specification can be combined in any appropriate manner to form various implementation methods. At the same time, the steps or actions in the method description can also be replaced or adjusted in order in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the accompanying drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a necessary sequence, unless otherwise specified that a certain sequence must be followed.

[0069] In the description of this application, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0070] The serial numbers of the components in this document, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings).

[0071] As people's living standards improve, in addition to requiring air conditioners to have basic cooling and heating functions, they also have higher and higher demands for air conditioning comfort, and the demand for high-temperature refrigeration is becoming more and more urgent.

[0072] However, as the outdoor ambient temperature continues to rise, the cooling load of the air-conditioning system increases, and the operating frequency of the compressor 700 and the speed of the fan need to be further increased. The current flowing through the main control board becomes larger, thus placing higher requirements on the heat dissipation of the main control board.

[0073] In the related art, the air conditioning system leads a short refrigerant tube 400 in the refrigerant circulation system to the main control board, and uses the refrigerant flowing through the short refrigerant tube 400 to cool down the electrical components on the main control board. Figure 1As shown, the air conditioning system in the related art includes an outdoor heat exchanger 100, an indoor heat exchanger 200, an expansion valve 300, a refrigerant short pipe 400, a one-way throttle valve 500, a four-way valve 600 and a compressor 700. The outdoor heat exchanger 100, the one-way throttle valve 500, the refrigerant short pipe 400, the expansion valve 300 and the indoor heat exchanger 200 are connected in sequence. The four-way valve 600 includes an S end, a C end, a D end and an E end. The C end of the four-way valve 600 is connected to the outdoor heat exchanger 100. The four-way valve The S end of 600 is connected to the air intake port of the compressor 700, the D end of the four-way valve 600 is connected to the exhaust port of the compressor 700, and the E end of the four-way valve 600 is connected to the indoor heat exchanger 200. In the cooling mode, the one-way throttle valve 500 is upstream of the refrigerant short pipe 400 and the direction of the one-way throttle valve 500 is opposite to the flow direction of the refrigerant. Due to the restriction of the one-way throttle valve 500, the flow rate of the refrigerant entering the refrigerant short pipe 400 is reduced, which is not conducive to high-temperature cooling and heating defrosting of the air-conditioning system.

[0074] Based on this, the embodiments of the present application provide a refrigeration method, a defrosting method, a controller and an air-conditioning system thereof.

[0075] The refrigeration method is such that in the refrigeration mode, the refrigerant passes through the expansion valve 300, the refrigerant heat dissipation component and the one-way throttle valve 500 in sequence, so that the refrigerant after throttling by the expansion valve 300 first passes through the refrigerant heat dissipation component and then reaches the one-way throttle valve 500. The refrigerant temperature in the refrigerant heat dissipation component can be lower, which helps the main control board to increase the current limit. Combined with the opening control of the expansion valve 300, the maximum operating frequency of the compressor 700 can be increased, thereby achieving better high-temperature refrigeration performance and broadening the applicable temperature range of high-temperature refrigeration.

[0076] The defrosting method adjusts the indoor fan, the compressor 700 and the expansion valve 300 before the air-conditioning system enters the defrost mode, and increases the opening of the expansion valve 300 after reducing the speed of the indoor fan and the operating frequency of the compressor 700, thereby increasing the temperature of the liquid refrigerant remaining in the indoor heat exchanger 200 and quickly transferring the liquid refrigerant to the outdoor heat exchanger 100, thereby defrosting the outdoor heat exchanger 100. The method is suitable for quickly melting thin frost on the outdoor heat exchanger 100, and completes the defrosting operation of the outdoor heat exchanger 100 without substantially affecting the indoor heating. At the same time, the problem of refrigerant sound in the indoor heat exchanger 200 after entering the defrost mode is solved.

[0077] The embodiments of the present application are further described below in conjunction with the accompanying drawings.

[0078] The embodiment of the present application provides a refrigeration method, which is applied to an air conditioning system. Figure 2As shown, the air conditioning system includes an outdoor heat exchanger 100, an indoor heat exchanger 200, an expansion valve 300, a refrigerant heat dissipation component and a one-way throttle valve 500. The outdoor heat exchanger 100, the expansion valve 300, the refrigerant heat dissipation component, the one-way throttle valve 500 and the indoor heat exchanger 200 are connected in sequence, the direction of the one-way throttle valve 500 points to the indoor heat exchanger 200, and the refrigerant heat dissipation component is used to perform heat exchange with the main control board of the air conditioning system; refer to Figure 3 As shown, the refrigeration method includes but is not limited to the following steps:

[0079] Step S100, when the outdoor ambient temperature is in the first temperature range and the current operating frequency of the compressor 700 of the air-conditioning system is lower than the first operating frequency, reducing the opening of the expansion valve 300 to reduce the temperature of the refrigerant in the refrigerant heat dissipation component, the first operating frequency is determined according to the target operating frequency of the compressor 700 and the first adjustment value;

[0080] It should be noted that the outdoor ambient temperature can be obtained by a temperature sensor detecting the temperature of the outdoor environment, and the first temperature interval is a pre-set temperature range. The target operating frequency is the operating frequency that the compressor 700 should reach, and the first adjustment value is the allowable deviation value. If the difference between the current operating frequency of the air-conditioning system and the target operating frequency is less than the first adjustment value, it can be considered that the current operating frequency reaches the target operating frequency, and there is no need to adjust the current operating frequency of the compressor 700. The first operating frequency is determined based on the target operating frequency of the compressor 700 and the first adjustment value. When the current operating frequency of the air-conditioning system is lower than the first operating frequency, it is confirmed that the current operating frequency of the air-conditioning system is lower than the target operating frequency, and the difference with the target operating frequency is greater than the first adjustment value, that is, the current operating frequency of the compressor 700 of the air-conditioning system fails to reach the target operating frequency, and the current operating frequency of the compressor 700 needs to be adjusted.

[0081] It should be noted that the first operating frequency is calculated by the following formula:

[0082] f1=f2-△1,

[0083] Wherein, f1 is the first operating frequency, f2 is the target operating frequency, and △1 is the first adjustment value.

[0084] It can be understood that when the outdoor ambient temperature is in the first temperature range and the current operating frequency of the compressor 700 of the air-conditioning system is lower than the first operating frequency, the opening of the expansion valve 300 is reduced, so that the temperature of the refrigerant in the refrigerant heat dissipation component is reduced, so as to enhance the heat dissipation effect of the refrigerant heat dissipation component on the main control board. The refrigerant heat dissipation component is the refrigerant short pipe 400, and the expansion valve 300 is an electronic expansion valve.

[0085] Step S200, increasing the current limit value of the main control board according to the temperature of the refrigerant in the refrigerant heat dissipation component, and increasing the current operating frequency of the compressor 700 according to the current limit value;

[0086] It should be noted that the current limiting value of the main control board determines the maximum current value flowing through the main control board. Since the current operating frequency of the compressor 700 is related to the current size, the larger the current, the higher the current operating frequency of the compressor 700. Therefore, the current limiting value of the main control board determines the current operating frequency of the compressor 700.

[0087] It can be understood that the lower the temperature of the refrigerant in the refrigerant heat dissipation component, the stronger the heat dissipation capacity of the main control board. Since the temperature of the refrigerant in the refrigerant heat dissipation component is reduced, the heat dissipation effect of the refrigerant heat dissipation component on the main control board is enhanced, which can meet the heat dissipation requirements of the main control board for a larger current. Therefore, according to the refrigerant temperature of the refrigerant heat dissipation component, the current limiting value of the main control board is increased so that a larger current can flow through the main control board, thereby increasing the current operating frequency of the compressor 700 according to the current limiting value, thereby enhancing the cooling effect of the air-conditioning system.

[0088] Step S300, when the current operating frequency of the compressor 700 is lower than the target operating frequency, the opening of the expansion valve 300 is reduced again to increase the current operating frequency of the compressor 700 again.

[0089] When the current operating frequency of the compressor 700 is lower than the target operating frequency, it means that the current operating frequency of the compressor 700 after adjustment still fails to reach the target operating frequency, and the opening of the expansion valve 300 is reduced again, so that the temperature of the refrigerant in the refrigerant heat dissipation component is further reduced, and the heat dissipation capacity of the main control board is further enhanced. According to the temperature of the refrigerant in the refrigerant heat dissipation component, the current limiting value of the main control board is increased again, so that a larger current can flow through the main control board, and the current operating frequency of the compressor 700 is increased according to the current limiting value. Repeat this step until the current operating frequency of the compressor 700 reaches the target operating frequency.

[0090] In this embodiment, under the cooling mode, the refrigerant passes through the expansion valve 300, the refrigerant heat dissipation component and the one-way throttle valve 500 in sequence, so that the refrigerant after throttling by the expansion valve 300 first passes through the refrigerant heat dissipation component and then reaches the one-way throttle valve 500. The refrigerant temperature in the refrigerant heat dissipation component can be lower, which helps the main control board to increase the current limit. Combined with the opening control of the expansion valve 300, the maximum operating frequency of the compressor 700 can be increased, achieving better high-temperature refrigeration performance and broadening the applicable temperature range of high-temperature refrigeration.

[0091] According to some embodiments of the present application, reducing the opening of the expansion valve 300 in the aforementioned steps specifically includes but is not limited to the following steps:

[0092] Step S110, reducing the opening of the expansion valve 300 according to a preset opening value.

[0093] In this embodiment, by setting a preset opening value, each time the opening of the expansion valve 300 is adjusted, the opening of the expansion valve 300 is reduced according to the preset opening value, and the opening of the expansion valve 300 is gradually reduced to avoid a single adjustment range of the opening of the expansion valve 300 being too large, causing the refrigerant temperature in the refrigerant heat dissipation component to drop sharply, so that the current limiting value of the main control board is greatly increased, and the current operating frequency of the compressor 700 is increased too quickly, which is not only easy to damage the equipment, but also may cause the current operating frequency of the compressor 700 to significantly exceed the target operating frequency.

[0094] According to some embodiments of the present application, referring to Figure 4 As shown, after reducing the opening of the expansion valve 300 according to the preset opening value, the refrigeration method further includes but is not limited to the following steps:

[0095] Step S120, obtaining the evaporation temperature of the indoor heat exchanger 200;

[0096] Since the evaporation temperature of the indoor heat exchanger 200 decreases as the opening of the expansion valve 300 decreases, when the evaporation temperature of the indoor heat exchanger 200 decreases, the power consumed by the compressor 700 increases, and the cooling capacity of the air-conditioning system decreases. By obtaining the evaporation temperature of the indoor heat exchanger 200, the opening of the expansion valve 300 can be controlled according to the evaporation temperature in the subsequent process, so as to avoid the expansion valve 300 being opened too small, thereby affecting the cooling effect of the air-conditioning system.

[0097] Step S130, when the evaporating temperature of the indoor heat exchanger 200 is lower than the preset evaporating temperature, the current opening of the expansion valve 300 is locked and the current operating frequency of the compressor 700 is maintained. The preset evaporating temperature is determined according to the maximum evaporating temperature and the protection margin temperature corresponding to the first temperature range.

[0098] By setting a preset evaporation temperature, when the evaporation temperature of the indoor heat exchanger 200 is lower than the preset evaporation temperature, the current opening of the expansion valve 300 is locked and the current operating frequency of the compressor 700 is maintained, so that the evaporation temperature of the indoor heat exchanger 200 does not drop any more. By comparing the preset evaporation temperature with the evaporation temperature of the indoor heat exchanger 200, the opening of the expansion valve 300 and the current operating frequency of the compressor 700 are controlled to avoid the evaporation temperature of the indoor heat exchanger 200 being too low due to the reduction of the opening of the expansion valve 300, while maintaining the current operating frequency of the compressor 700 to ensure the cooling effect of the air-conditioning system.

[0099] It can be understood that the preset evaporation temperature is determined according to the maximum evaporation temperature and the protection margin temperature corresponding to the first temperature interval. Specifically, the preset evaporation temperature is calculated by the following formula:

[0100] T1=T2-△2,

[0101] Wherein, T1 is the preset evaporation temperature, T2 is the maximum evaporation temperature corresponding to the first temperature range, and △2 is the protection margin temperature.

[0102] According to some embodiments of the present application, the refrigeration method includes but is not limited to:

[0103] Step S400, when the outdoor ambient temperature is in the first temperature range and the current operating frequency of the compressor 700 is higher than the first operating frequency, or when the outdoor ambient temperature is in the second temperature range or the third temperature range, adjusting the opening of the expansion valve 300 according to the opening range corresponding to the current temperature range and the exhaust gas superheat of the compressor 700;

[0104] The lower limit temperature of the first temperature interval is greater than the upper limit temperature of the second temperature interval, and the lower limit temperature of the second temperature interval is greater than the upper limit temperature of the third temperature interval.

[0105] It should be noted that the first temperature interval, the second temperature interval and the third temperature interval are set respectively, the lower limit temperature of the first temperature interval is greater than the upper limit temperature of the second temperature interval, and the lower limit temperature of the second temperature interval is greater than the upper limit temperature of the third temperature interval, for example, the first temperature interval is (Tb, Tc), the second temperature interval is (Ta, Tb), and the third temperature interval is (Tmin, Ta). The first temperature interval, the second temperature interval and the third temperature interval cover different temperature ranges. When the outdoor ambient temperature is in the first temperature interval, the air conditioning system is in an ultra-high temperature cooling state, when the outdoor ambient temperature is in the second temperature interval, the air conditioning system is in an overload cooling state, and when the outdoor ambient temperature is in the third temperature interval, the air conditioning system is in a normal cooling state.

[0106] The first temperature interval, the second temperature interval and the third temperature interval are respectively provided with corresponding opening ranges. When the outdoor ambient temperature is in the first temperature interval and the current operating frequency of the compressor 700 is higher than the first operating frequency, or when the outdoor ambient temperature is in the second temperature interval or the third temperature interval, the opening of the expansion valve 300 is adjusted according to the opening range corresponding to the current temperature interval and the exhaust superheat, so as to realize precise adjustment of the opening of the expansion valve 300.

[0107] According to some embodiments of the present application, referring to Figure 5 As shown, in step S400, the opening of the expansion valve 300 is adjusted according to the opening range corresponding to the current temperature range and the exhaust superheat of the compressor 700; including but not limited to:

[0108] Step S410, determining the initial opening of the expansion valve 300 according to the outdoor ambient temperature and the target operating frequency of the compressor 700;

[0109] Step S420, adjusting the initial opening of the expansion valve 300 according to the exhaust superheat of the compressor 700 and the superheat control coefficient corresponding to the current temperature range, and controlling the opening of the expansion valve 300 not to exceed the opening range corresponding to the current temperature range;

[0110] In this embodiment, the initial opening of the expansion valve 300 is determined according to the outdoor ambient temperature and the target operating frequency of the compressor 700. Furthermore, the initial opening of the expansion valve 300 is adjusted according to the exhaust superheat of the compressor 700 and the superheat control coefficient corresponding to the current temperature, and the opening of the expansion valve 300 is controlled not to exceed the opening range corresponding to the current temperature range. The initial opening of the expansion valve 300 can be accurately determined, so that the air conditioning system can achieve a good cooling effect in the current temperature range. It should be noted that the superheat control coefficient is determined by the joint evaluation of the exhaust superheat of the compressor 700, the capacity of the air conditioning system, the energy efficiency, and the return liquid visualization associated conditions.

[0111] After the above description, this embodiment is also described using a specific example. Figure 6 As shown, the refrigeration method specifically includes the following steps:

[0112] Step S1, when the outdoor ambient temperature is in a first temperature range and the current operating frequency of the compressor 700 of the air conditioning system is lower than the first operating frequency, the opening of the expansion valve 300 is reduced according to a preset opening value to reduce the temperature of the refrigerant in the refrigerant heat dissipation component;

[0113] Step S2, increasing the current limit value of the main control board according to the temperature of the refrigerant in the refrigerant heat dissipation component, and increasing the current operating frequency of the compressor 700 according to the current limit value;

[0114] Step S3, obtaining the evaporation temperature of the indoor heat exchanger 200;

[0115] Step S4, when the evaporation temperature of the indoor heat exchanger 200 is lower than the preset evaporation temperature, the current opening of the expansion valve 300 is locked and the current operating frequency of the compressor 700 is maintained;

[0116] Step S5, when the current operating frequency of the compressor 700 is lower than the target operating frequency, the opening of the expansion valve 300 is reduced again to increase the current operating frequency of the compressor 700 again;

[0117] Step S6, when the outdoor ambient temperature is in the first temperature range and the current operating frequency of the compressor 700 is higher than the first operating frequency, or when the outdoor ambient temperature is in the second temperature range or the third temperature range, determining the initial opening of the expansion valve 300 according to the outdoor ambient temperature and the target operating frequency of the compressor 700;

[0118] Step S7, adjusting the initial opening of the expansion valve 300 according to the exhaust superheat of the compressor 700 and the superheat control coefficient corresponding to the current temperature range, and controlling the opening of the expansion valve 300 not to exceed the opening range corresponding to the current temperature range.

[0119] In addition, the present application also provides a defrosting method, which is applied to an air conditioning system, such as Figure 2 As shown, the air conditioning system includes an outdoor heat exchanger 100, an indoor heat exchanger 200, an expansion valve 300, a refrigerant heat dissipation component and a one-way throttle valve 500. The outdoor heat exchanger 100, the expansion valve 300, the refrigerant heat dissipation component, the one-way throttle valve 500 and the indoor heat exchanger 200 are connected in sequence, the direction of the one-way throttle valve 500 points to the indoor heat exchanger 200, and the refrigerant heat dissipation component is used to perform heat exchange with the main control board of the air conditioning system; refer to Figure 7 As shown, the defrosting method includes but is not limited to the following steps:

[0120] S1100, before entering the defrost mode, reduce the speed of the indoor fan of the air conditioning system;

[0121] S2100, after reducing the operating frequency of the compressor 700 of the air-conditioning system, the opening degree of the expansion valve 300 is increased.

[0122] In this embodiment, the indoor fan, compressor 700 and expansion valve 300 are adjusted before the air-conditioning system enters the defrost mode. By reducing the speed of the indoor fan and the operating frequency of the compressor 700 and then increasing the opening of the expansion valve 300, the temperature of the liquid refrigerant remaining in the indoor heat exchanger 200 is increased and the liquid refrigerant is quickly transferred to the outdoor heat exchanger 100, thereby defrosting the outdoor heat exchanger 100. The method of this embodiment is suitable for quickly melting thin frost on the outdoor heat exchanger 100, and the defrost operation of the outdoor heat exchanger 100 is completed without substantially affecting the indoor heating. At the same time, the problem of refrigerant sound in the indoor heat exchanger 200 after entering the defrost mode is solved.

[0123] It should be noted that, refer to Figures 8 to 9 As shown, the defrost mode includes defrost mode A and defrost mode B, and an instruction stage is set before defrost mode A and defrost mode B.

[0124] According to some embodiments of the present application, referring to Fig.10 As shown, in step S2100, after reducing the operating frequency of the compressor 700 of the air-conditioning system, increasing the opening of the expansion valve 300 includes but is not limited to the following steps:

[0125] Step S2110, obtaining the coil temperature of the outdoor heat exchanger 100;

[0126] Step S2120, when the coil temperature is greater than the first temperature value, at a first moment before entering the defrost mode, reducing the operating frequency of the compressor 700 of the air conditioning system;

[0127] In step S2130, when the operating frequency of the compressor 700 of the air-conditioning system drops to the second operating frequency, the opening of the expansion valve 300 is increased and the opening of the expansion valve 300 is increased to the first opening when entering the defrost mode.

[0128] In this embodiment, the defrost mode A obtains the tube coil temperature of the outdoor heat exchanger 100 by setting a first temperature value, and compares the tube coil temperature with the first temperature value. When the tube coil temperature is greater than the first temperature value, the operating frequency of the compressor 700 of the air-conditioning system is reduced at the first moment before entering the defrost mode A. When the operating frequency of the compressor 700 drops to the second operating frequency, the opening of the expansion valve 300 is increased, so that the opening of the expansion valve 300 increases to the first opening when entering the defrost mode A. Therefore, before entering the defrost mode A, the temperature of the liquid refrigerant staying in the indoor heat exchanger 200 is increased, so that it can be quickly transferred to the outdoor heat exchanger 100 after entering the defrost mode A to defrost the outdoor heat exchanger 100.

[0129] It should be noted that before entering defrost mode A, the speed of the indoor fan of the air-conditioning system is reduced to a preset first speed.

[0130] According to some embodiments of the present application, referring to Fig.11 As shown, in step S2100, after reducing the operating frequency of the compressor 700 of the air-conditioning system, increasing the opening of the expansion valve 300 includes but is not limited to the following steps:

[0131] Step S2140, obtaining the coil temperature of the outdoor heat exchanger 100;

[0132] Step S2150, when the coil temperature is less than the first temperature value and greater than the second temperature value, at a second moment before entering the defrost mode, the operating frequency of the compressor 700 is reduced and the opening of the expansion valve 300 is increased, and the second moment is earlier than the first moment;

[0133] Step S2160, when the operating frequency of the compressor 700 drops to the third operating frequency and the opening of the expansion valve 300 increases to the second opening, the current operating frequency of the compressor 700 and the current opening of the expansion valve 300 are maintained until entering the defrost mode.

[0134] In this embodiment, the defrost mode B obtains the tube coil temperature of the outdoor heat exchanger 100 by setting the second temperature value. When the tube coil temperature of the outdoor heat exchanger 100 is less than the first temperature value and greater than the second temperature value, that is, the tube coil temperature is in a relatively low state, at a second moment before entering the defrost mode, the operating frequency of the compressor 700 is reduced and the opening of the expansion valve 300 is increased. The second moment is earlier than the first moment. It takes a longer time for the operating frequency of the compressor 700 to drop to the third operating frequency and the opening of the expansion valve 300 to increase to the second opening, thereby increasing the liquid refrigerant temperature of the indoor heat exchanger 200, maintaining the current operating frequency of the compressor 700 and the current opening of the expansion valve 300 until entering the defrost mode, so that the liquid refrigerant with a higher temperature is quickly transferred to the outdoor heat exchanger 100, and the outdoor heat exchanger 100 is defrosted. When the tube coil temperature is in a relatively low state, a good defrost effect is ensured.

[0135] It should be noted that before entering defrost mode B, the speed of the outdoor fan of the air-conditioning system is reduced to a preset first speed, that is, before entering defrost mode A and defrost mode B, the speed of the outdoor fan of the air-conditioning system is reduced to the preset first speed. Before entering defrost mode B, the speed of the outdoor fan of the air-conditioning system can also be reduced to a preset second speed, that is, before entering defrost mode B and before entering defrost mode A, the speed value of the speed reduction of the outdoor fan is different.

[0136] According to some embodiments of the present application, referring to Fig.12 As shown, the defrosting method also includes but is not limited to the following steps:

[0137] Step S2170, after entering the defrost mode, shut down the outdoor fan of the air conditioning system;

[0138] Step S2180, controlling the operating frequency of the compressor 700 to drop to a fourth operating frequency.

[0139] In this embodiment, after entering the defrost mode A, the outdoor fan of the air-conditioning system is shut down, and the operating frequency of the compressor 700 is reduced to the fourth operating frequency. As the opening of the expansion valve 300 increases, the outdoor fan stops, the compression ratio of the air-conditioning system decreases, and the refrigerant flow rate decreases, which can improve the defrosting effect in the micro-frost stage. In addition, since the resident liquid refrigerant in the indoor heat exchanger 200 is reduced, the two-phase refrigerant sound caused by the flash evaporation of the resident liquid refrigerant after the high-pressure pressure is reduced is improved.

[0140] According to some embodiments of the present application, referring to Fig.13 As shown, the defrosting method also includes but is not limited to the following steps:

[0141] Step S2171, after entering the defrost mode, shut down the outdoor fan of the air conditioning system, and reduce the speed of the indoor fan to 0 within a preset time;

[0142] Step S2181, controlling the operating frequency of the compressor 700 to drop to a fifth operating frequency;

[0143] Step S2191, controlling the opening degree of the expansion valve 300 to increase to the third opening degree and then to the fourth opening degree.

[0144] In this embodiment, after entering the defrost mode B, the outdoor fan of the air-conditioning system is shut down, the speed of the indoor fan is set to 0 for a preset period of time, the operating frequency of the compressor 700 is controlled to drop to the fifth operating frequency, and the opening of the expansion valve 300 is controlled to increase to the third opening and then to the fourth opening, so that the temperature of the indoor heat exchanger 200 changes slowly, thereby significantly improving the thermal expansion and contraction noise of the air-conditioning system.

[0145] According to some embodiments of the present application, the air conditioning system further includes a four-way valve 600; before and after entering the defrost mode, the valve state of the four-way valve 600 does not change.

[0146] In this embodiment, the air conditioning system further includes a four-way valve 600, and the switching between the cooling mode and the heating mode of the air conditioning system is realized by switching the four-way valve 600. The traditional defrosting technology of the air conditioning system usually uses the four-way valve 600 to switch the cooling mode for periodic defrosting. During the defrosting process, the indoor fan stops running, stops the hot air output, and the outdoor heat exchanger 100 is defrosted. The higher the outdoor environmental humidity, the more frequent the defrosting. Frequent defrosting of the air conditioning system is bound to cause a significant drop in indoor temperature, and the human body perceives poor comfort. In this embodiment, defrosting is not performed by switching the four-way valve 600. Before and after the defrosting mode, the valve state of the four-way valve 600 does not change, and the air conditioning system can still operate in the heating mode without stopping the switching of the defrosting mode. That is, during the heating process of the air conditioning system, it can continue to defrost and ice, and there is no need to stop the heating mode to switch the defrosting mode, which significantly improves the user experience and comfort.

[0147] It is understandable that in the defrost mode, the air conditioning system still operates in the heating mode, the indoor heat exchanger 200 is in a high temperature state, and the valve state of the four-way valve 600 does not change, that is, there is no need to switch to the cooling mode, thus avoiding thermal expansion and contraction.

[0148] After the above description, this embodiment is also described using a specific example. Fig.14 As shown, the defrosting method (defrosting mode A) specifically includes the following steps:

[0149] Step S10, before entering defrost mode A, reducing the speed of the indoor fan of the air conditioning system to a preset first speed;

[0150] Step S11, obtaining the coil temperature of the outdoor heat exchanger 100;

[0151] Step S12, when the coil temperature is greater than the first temperature value, at the first moment before entering the defrost mode A, reducing the operating frequency of the compressor 700 of the air conditioning system;

[0152] Step S13, when the operating frequency of the compressor 700 of the air conditioning system drops to the second operating frequency, the opening of the expansion valve 300 is increased and the opening of the expansion valve 300 is increased to the first opening when entering the defrost mode A;

[0153] Step S14, after entering defrost mode A, shut down the outdoor fan of the air conditioning system;

[0154] Step S15, controlling the operating frequency of the compressor 700 to drop to a fourth operating frequency.

[0155] After the above description, this embodiment is also described using a specific example. Fig.15 As shown, the defrosting method (defrosting mode B) specifically includes the following steps:

[0156] Step S20, before entering defrost mode B, reducing the speed of the indoor fan of the air conditioning system to a preset second speed;

[0157] Step S21, obtaining the coil temperature of the outdoor heat exchanger 100;

[0158] Step S22, when the coil temperature is less than the first temperature value and greater than the second temperature value, at a second moment before entering defrost mode B, the operating frequency of the compressor 700 is reduced and the opening of the expansion valve 300 is increased, and the second moment is earlier than the first moment;

[0159] Step S23, when the operating frequency of the compressor 700 drops to the third operating frequency and the opening of the expansion valve 300 increases to the second opening, the current operating frequency of the compressor 700 and the current opening of the expansion valve 300 are maintained until entering the defrost mode B;

[0160] Step S24, after entering defrost mode B, shut down the outdoor fan of the air conditioning system, and reduce the speed of the indoor fan to 0 within a preset time;

[0161] Step S25, controlling the operating frequency of the compressor 700 to drop to a fifth operating frequency;

[0162] Step S26, controlling the opening degree of the expansion valve 300 to increase to the third opening degree and then to the fourth opening degree.

[0163] In addition, an embodiment of the present application also provides a controller, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the above-mentioned refrigeration method or the above-mentioned defrosting method when executing the computer program.

[0164] In this embodiment, when the processor runs the computer program to execute the refrigeration method as described above, in the refrigeration mode, the refrigerant passes through the expansion valve 300, the refrigerant heat dissipation component and the one-way throttle valve 500 in sequence, so that the refrigerant after throttling by the expansion valve 300 first passes through the refrigerant heat dissipation component and then reaches the one-way throttle valve 500. The refrigerant temperature in the refrigerant heat dissipation component can be lower, which helps the main control board to increase the current limit. Combined with the opening control of the expansion valve 300, the maximum operating frequency of the compressor 700 can be increased, achieving better high-temperature refrigeration performance and broadening the applicable temperature range of high-temperature refrigeration.

[0165] In this embodiment, when the processor runs the computer program to execute the defrost method as described above, the indoor fan, compressor 700 and expansion valve 300 are adjusted before the air-conditioning system enters the defrost mode. By reducing the speed of the indoor fan and the operating frequency of the compressor 700 and then increasing the opening of the expansion valve 300, the temperature of the liquid refrigerant remaining in the indoor heat exchanger 200 is increased and the liquid refrigerant is quickly transferred to the outdoor heat exchanger 100, thereby defrosting the outdoor heat exchanger 100. The method of this embodiment is suitable for the rapid melting of thin frost on the outdoor heat exchanger 100, and the defrost operation of the outdoor heat exchanger 100 is completed without substantially affecting the indoor heating. At the same time, the problem of refrigerant sound in the indoor heat exchanger 200 after entering the defrost mode is solved.

[0166] In addition, an embodiment of the present application also provides an air conditioning system, including the controller as described above.

[0167] In this embodiment, when the processor of the controller of the air-conditioning system runs a computer program to execute the refrigeration method as described above, in the refrigeration mode, the refrigerant passes through the expansion valve 300, the refrigerant heat dissipation component and the one-way throttle valve 500 in sequence, so that the refrigerant after throttling by the expansion valve 300 first passes through the refrigerant heat dissipation component and then reaches the one-way throttle valve 500. The refrigerant temperature in the refrigerant heat dissipation component can be lower, which helps the main control board to increase the current limit. Combined with the opening control of the expansion valve 300, the maximum operating frequency of the compressor 700 can be increased, achieving better high-temperature refrigeration performance and broadening the applicable temperature range of high-temperature refrigeration.

[0168] In this embodiment, when the processor of the controller of the air-conditioning system runs a computer program to execute the defrosting method as described above, the indoor fan, compressor 700 and expansion valve 300 are adjusted before the air-conditioning system enters the defrost mode. By reducing the speed of the indoor fan and the operating frequency of the compressor 700 and then increasing the opening of the expansion valve 300, the temperature of the liquid refrigerant remaining in the indoor heat exchanger 200 is increased and the liquid refrigerant is quickly transferred to the outdoor heat exchanger 100, thereby defrosting the outdoor heat exchanger 100. The method of this embodiment is suitable for the rapid melting of thin frost on the outdoor heat exchanger 100, and the defrosting operation of the outdoor heat exchanger 100 is completed without substantially affecting the indoor heating. At the same time, the problem of refrigerant sound in the indoor heat exchanger 200 after entering the defrost mode is solved.

[0169] The device embodiments described above are merely illustrative, and the units described as separate components may or may not be physically separated, that is, they may be located in one place or distributed on multiple network nodes. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0170] It will be appreciated by those skilled in the art that all or some of the steps and systems in the disclosed method above may be implemented as software, firmware, hardware and appropriate combinations thereof. Some physical components or all physical components may be implemented as software executed by a processor, such as a central processing unit, a digital signal processor or a microprocessor, or may be implemented as hardware, or may be implemented as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer-readable storage medium (or a non-transitory medium) and a communication medium (or a temporary medium). As known to those skilled in the art, the term computer-readable storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules or other data). Computer-readable storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, disk storage or other magnetic storage devices, or any other medium that may be used to store desired information and may be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically embodies computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0171] The above is a specific description of the preferred implementation of the present application, but the present application is not limited to the above-mentioned implementation mode. Technical personnel familiar with the field can also make various equivalent deformations or substitutions without violating the spirit of the present application. These equivalent deformations or substitutions are all included in the scope defined by the claims of the present application.

Claims

1. A refrigeration method, characterized in that: Applied to an air conditioning system, the air conditioning system includes an outdoor heat exchanger, an indoor heat exchanger, an expansion valve, a refrigerant heat dissipation component and a one-way throttle valve, the outdoor heat exchanger, the expansion valve, the refrigerant heat dissipation component, the one-way throttle valve and the indoor heat exchanger are connected in sequence, the direction of the one-way throttle valve points to the indoor heat exchanger, and the refrigerant heat dissipation component is used to perform heat exchange with the main control board of the air conditioning system; the refrigeration method includes: When the outdoor ambient temperature is in a first temperature range and the current operating frequency of the compressor of the air-conditioning system is lower than a first operating frequency, reducing the opening of the expansion valve to reduce the temperature of the refrigerant in the refrigerant heat dissipation component, the first operating frequency being determined according to the target operating frequency of the compressor and a first adjustment value; Increasing the current limiting value of the main control board according to the temperature of the refrigerant in the refrigerant heat dissipation component, and increasing the current operating frequency of the compressor according to the current limiting value; When the current operating frequency of the compressor is lower than the target operating frequency, the opening of the expansion valve is reduced again to increase the current operating frequency of the compressor again.

2. The refrigeration method according to claim 1, characterized in that: The reducing the opening of the expansion valve comprises: The opening of the expansion valve is reduced according to a preset opening value.

3. The refrigeration method according to claim 2, characterized in that: After reducing the opening of the expansion valve according to the preset opening value, the refrigeration method further includes: Obtaining the evaporation temperature of the indoor heat exchanger; When the evaporating temperature of the indoor heat exchanger is lower than a preset evaporating temperature, the current opening of the expansion valve is locked and the current operating frequency of the compressor is maintained. The preset evaporating temperature is determined according to the maximum evaporating temperature and the protection margin temperature corresponding to the first temperature range.

4. The refrigeration method according to claim 1, characterized in that: The refrigeration method comprises: When the outdoor ambient temperature is in the first temperature range and the current operating frequency of the compressor is higher than the first operating frequency, or when the outdoor ambient temperature is in the second temperature range or the third temperature range, adjusting the opening of the expansion valve according to the opening range corresponding to the current temperature range and the exhaust superheat of the compressor; The lower limit temperature of the first temperature interval is greater than the upper limit temperature of the second temperature interval, and the lower limit temperature of the second temperature interval is greater than the upper limit temperature of the third temperature interval.

5. The refrigeration method according to claim 4, characterized in that: The method of adjusting the opening of the expansion valve according to the opening range corresponding to the current temperature interval and the exhaust superheat of the compressor comprises: determining an initial opening degree of the expansion valve according to the outdoor ambient temperature and the target operating frequency of the compressor; Adjusting the initial opening of the expansion valve according to the exhaust superheat of the compressor and the superheat control coefficient corresponding to the current temperature range, and controlling the opening of the expansion valve not to exceed the opening range corresponding to the current temperature range; Wherein, the superheat control coefficient is determined according to the exhaust temperature of the compressor.

6. A defrosting method, characterized in that: Applied to an air conditioning system, the air conditioning system comprises an outdoor heat exchanger, an indoor heat exchanger, an expansion valve, a refrigerant heat dissipation component and a one-way throttle valve, the outdoor heat exchanger, the expansion valve, the refrigerant heat dissipation component, the one-way throttle valve and the indoor heat exchanger are connected in sequence, the direction of the one-way throttle valve points to the indoor heat exchanger, and the refrigerant heat dissipation component is used to perform heat exchange with the main control board of the air conditioning system; the defrosting method comprises: Before entering the defrost mode, reducing the speed of the indoor fan of the air conditioning system; The opening of the expansion valve is increased after the operating frequency of the compressor of the air conditioning system is reduced.

7. The defrosting method according to claim 6, characterized in that: The step of increasing the opening of the expansion valve after reducing the operating frequency of the compressor of the air conditioning system comprises: Obtaining the coil temperature of the outdoor heat exchanger; When the coil temperature is greater than a first temperature value, at a first moment before entering a defrost mode, reducing the operating frequency of the compressor of the air conditioning system; When the operating frequency of the compressor of the air-conditioning system decreases to the second operating frequency, the opening degree of the expansion valve is increased and the opening degree of the expansion valve is increased to the first opening degree when entering the defrost mode.

8. The defrosting method according to claim 7, characterized in that: The step of increasing the opening of the expansion valve after reducing the operating frequency of the compressor of the air conditioning system comprises: Obtaining the coil temperature of the outdoor heat exchanger; When the coil temperature is less than the first temperature value and greater than a second temperature value, at a second moment before entering the defrost mode, the operating frequency of the compressor is reduced and the opening of the expansion valve is increased, and the second moment is earlier than the first moment; When the operating frequency of the compressor drops to the third operating frequency and the opening of the expansion valve increases to the second opening, the current operating frequency of the compressor and the current opening of the expansion valve are maintained until entering the defrosting mode.

9. The defrosting method according to claim 7, characterized in that: The defrosting method further comprises: After entering the defrost mode, shutting down the outdoor fan of the air conditioning system; The operating frequency of the compressor is controlled to drop to a fourth operating frequency.

10. The defrosting method according to claim 8, characterized in that: The defrosting method further comprises: After entering the defrost mode, the outdoor fan of the air conditioning system is turned off, and the speed of the indoor fan is reduced to 0 within a preset time; controlling the operating frequency of the compressor to drop to a fifth operating frequency; The opening degree of the expansion valve is controlled to increase to a third opening degree and then to a fourth opening degree.

11. The defrosting method according to any one of claims 6 to 10, characterized in that: The air conditioning system further comprises a four-way valve; before and after entering the defrost mode, the valve state of the four-way valve does not change.

12. A controller, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the refrigeration method according to any one of claims 1 to 5 or the defrosting method according to any one of claims 6 to 11 when executing the computer program.

13. An air conditioning system, characterized in that: Comprising a controller as claimed in claim 12.

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