Air conditioning system and defrosting control method thereof

Abstract

An air conditioning system (100) has a cooling mode, a heating mode, and a de-frosting mode. The air conditioning system (100) comprises an indoor unit (10) and an outdoor unit (20). The indoor unit (10) comprises an indoor heat exchanger (101). The outdoor unit (20) comprises a compressor (21), a first branch (41) and an outdoor heat exchanger assembly (3). The compressor (21) comprises an air suction port (211) and an exhaust port (212). The outdoor heat exchanger assembly (3) comprises a first part (31) and a second part (32), and the first part (31) is communicated with the second part (32) through the first branch (41). Wherein, under the condition that the air conditioning system (100) operates in the defrosting-free mode, the indoor heat exchanger (101) is communicated with the exhaust port (212) of the compressor (21), and is communicated with the second part (32); and the first part (31) is communicated with the air suction port (211) of the compressor (21). At least part of the first portion (31) overlaps at least part of the second portion (32), and the second portion (32) is configured to exchange heat (31) with the first portion.

Description

Air conditioning system and defrosting control method thereof

[0001] This application claims priority to Chinese patent application No. CN202310506237.6, filed on May 5, 2023; and No. CN202310506368.4, filed on May 5, 2023, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present disclosure relates to the technical field of air conditioning, and in particular to an air conditioning system and a defrosting control method thereof. Background Art

[0003] When the air conditioning system is operating in heating mode, if the ambient temperature and humidity reach certain conditions, the outdoor heat exchanger components will frost, affecting the performance of the air conditioning system. The refrigerant discharged from the compressor can be supplied to the outdoor heat exchanger components, thereby using the heat of the refrigerant to defrost the outdoor heat exchanger components.

[0004] Summary of the Invention

[0005] In one aspect, an air conditioning system is provided, comprising an indoor unit and an outdoor unit. The indoor unit includes an indoor heat exchanger. The outdoor unit includes a compressor, a first branch, and an outdoor heat exchanger assembly. The compressor includes an air intake and an air discharge. The outdoor heat exchanger assembly includes a first portion and a second portion, the first portion communicating with the second portion via the first branch. When the air conditioning system operates in the defrost-free mode, the indoor heat exchanger communicates with the compressor's air discharge and with the second portion; the first portion communicates with the compressor's air intake. At least a portion of the first portion overlaps with at least a portion of the second portion, and the second portion is configured to exchange heat with the first portion.

[0006] In another aspect, an air conditioning system is provided, comprising a controller, an indoor heat exchanger, and an outdoor unit. The outdoor unit comprises a compressor, a reversing assembly, an outdoor heat exchanger assembly, a fourth branch, a fifth branch, a first branch, a first on-off valve, a second on-off valve, a first throttle valve, a second throttle valve, a third throttle valve, and a throttle assembly. The compressor comprises an intake port and an exhaust port, and the reversing assembly comprises a first valve port, a second valve port, a third valve port, and a fourth valve port. The first valve port is connected to the exhaust port, and the fourth valve port is connected to the intake port. The outdoor heat exchanger assembly comprises a first portion and a second portion, with the first end of the first portion being connected to the third valve port. The first end of the fourth branch is connected to the exhaust port, and the second end of the fourth branch is connected to the second end of the first portion. The first end of the fifth branch is connected to the exhaust port, and the first end of the first branch is connected to the second end of the first portion. One of the second ends of the fifth branch and the second end of the first branch is connected to the second end of the second portion, and the other is connected to the first end of the second portion. The first on-off valve is disposed in the fourth branch, the second on-off valve is disposed between the first end of the second portion and the third valve port, the first throttle valve is disposed in the first branch, and the throttle assembly is disposed in the fifth branch. The first end of the indoor heat exchanger is connected to the second valve port; the second throttle valve is disposed between the second end of the indoor heat exchanger and the second end of the first portion, and the third throttle valve is disposed between the second end of the indoor heat exchanger and the second end of the second portion. The controller is electrically connected to the indoor heat exchanger and the outdoor unit, and is configured as follows: when the air-conditioning system is controlled to defrost the first part of the outdoor unit, the first valve port and the second valve port of the outdoor unit are controlled to be connected, the third valve port and the fourth valve port are controlled to be connected, the first on-off valve and the second on-off valve are controlled to be opened, the first throttle valve and the throttling assembly are fully closed, and the third throttle valve is controlled to be throttled; and when the air-conditioning system is controlled to defrost the second part of the outdoor unit, the first valve port and the second valve port of the outdoor unit are controlled to be connected, the third valve port and the fourth valve port are controlled to be connected, the first throttle valve, the second throttle valve and the throttling assembly are controlled to be throttled, and the first on-off valve and the second on-off valve are controlled to be closed.

[0007] On the other hand, a defrost control method for an air-conditioning system is provided, and the defrost control method satisfies one of the following: the defrost control method includes: when the air-conditioning system operates in a heating mode, if the air-conditioning system meets the defrost conditions, controlling the air-conditioning system to operate a first defrost mode to defrost the first part of the outdoor unit, wherein the defrost conditions include the outdoor ambient temperature, the operating time of the air-conditioning system, and the temperature of the first part of the outdoor unit or the temperature of the second part of the outdoor unit; if the air-conditioning system completes defrosting the first part of the outdoor unit, controlling the air-conditioning system to exit the first defrost mode and operate a second defrost mode to defrost the second part of the outdoor unit; if the air-conditioning system completes defrosting the second part of the outdoor unit, controlling the air-conditioning system to exit the second defrost mode. Alternatively, the defrost control method includes: when the air-conditioning system operates in a heating mode, if the air-conditioning system meets the defrost conditions, controlling the air-conditioning system to operate in a second defrost mode to defrost the second part of the outdoor unit, the defrost conditions including the outdoor ambient temperature, the operating time of the air-conditioning system, and the temperature of at least one of the first parts or the temperature of at least one of the second parts; if the air-conditioning system has completed defrosting the second part of the outdoor unit, controlling the air-conditioning system to exit the second defrost mode and operate the first defrost mode to defrost the first part of the outdoor unit; if the air-conditioning system has completed defrosting the first part of the outdoor unit, controlling the air-conditioning system to exit the first defrost mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG1 is a schematic diagram of an air conditioning system according to some embodiments;

[0009] FIG2 is a schematic diagram of another air conditioning system according to some embodiments;

[0010] FIG3 is a schematic diagram of another air conditioning system according to some embodiments;

[0011] FIG4 is a schematic diagram of another air conditioning system according to some embodiments;

[0012] FIG5 is a schematic diagram of another air conditioning system according to some embodiments;

[0013] FIG6 is a schematic diagram of another air conditioning system according to some embodiments;

[0014] FIG7 is a schematic diagram of another air conditioning system according to some embodiments;

[0015] FIG8 is a schematic diagram of another air conditioning system according to some embodiments;

[0016] FIG9 is a schematic diagram of another air conditioning system according to some embodiments;

[0017] FIG10 is a schematic diagram of another air conditioning system according to some embodiments;

[0018] FIG11 is a schematic diagram of another air conditioning system according to some embodiments;

[0019] FIG12 is a schematic diagram of another air conditioning system according to some embodiments;

[0020] FIG13 is a schematic diagram of another air conditioning system according to some embodiments;

[0021] FIG14 is a schematic diagram of another air conditioning system according to some embodiments;

[0022] FIG15 is a schematic diagram of another air conditioning system according to some embodiments;

[0023] FIG16 is a schematic diagram of the air-conditioning system shown in FIG4 when operating in cooling mode;

[0024] FIG17 is a schematic diagram of the air-conditioning system shown in FIG5 when operating in cooling mode;

[0025] FIG18 is a schematic diagram of the air-conditioning system shown in FIG4 when operating in a heating mode;

[0026] FIG19 is a schematic diagram of the air-conditioning system shown in FIG5 when operating in a heating mode;

[0027] FIG20 is a schematic diagram of the air conditioning system shown in FIG4 when defrosting the first part;

[0028] FIG21 is a schematic diagram of the air conditioning system shown in FIG5 when defrosting the first part;

[0029] FIG22 is a schematic diagram of the air conditioning system shown in FIG4 when defrosting the second part;

[0030] FIG23 is a schematic diagram of the air conditioning system shown in FIG5 when defrosting the second part;

[0031] FIG24 is a flow chart of a defrost control method for an air-conditioning system according to some embodiments of the present disclosure;

[0032] FIG25 is a flow chart of another defrost control method for an air-conditioning system according to some embodiments of the present disclosure;

[0033] FIG26 is a flowchart of another defrost control method for an air-conditioning system according to some embodiments of the present disclosure;

[0034] FIG27 is a flowchart of another defrost control method for an air-conditioning system according to some embodiments of the present disclosure;

[0035] FIG28 is a flowchart of another defrost control method for an air-conditioning system according to some embodiments of the present disclosure;

[0036] FIG29 is a flowchart of another defrost control method for an air-conditioning system according to some embodiments of the present disclosure;

[0037] FIG30 is a flowchart of another defrost control method for an air-conditioning system according to some embodiments of the present disclosure;

[0038] FIG31 is a flowchart of another defrost control method for an air-conditioning system according to some embodiments of the present disclosure;

[0039] FIG32 is a schematic diagram of another air conditioning system according to some embodiments of the present disclosure;

[0040] FIG33 is a flowchart of another defrost control method for an air-conditioning system according to some embodiments of the present disclosure;

[0041] FIG34 is a flowchart of another defrost control method for an air-conditioning system according to some embodiments of the present disclosure;

[0042] FIG35 is a flowchart of another defrost control method for an air-conditioning system according to some embodiments of the present disclosure;

[0043] FIG36 is a flowchart of another defrost control method for an air-conditioning system according to some embodiments of the present disclosure;

[0044] FIG37 is a flowchart of another defrost control method for an air-conditioning system according to some embodiments of the present disclosure;

[0045] FIG38 is a flowchart of another defrost control method for an air-conditioning system according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0046] The following will be combined with the accompanying drawings to clearly and completely describe some embodiments of the present disclosure. Obviously, the embodiments described are only some embodiments of the present disclosure, rather than all embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present disclosure.

[0047] Unless the context requires otherwise, throughout the specification and claims, the term "comprise" and its other forms, such as the third person singular form "comprises" and the present participle form "comprising", are to be interpreted as open and inclusive, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "example", "specific example" or "some examples" are intended to indicate that the particular features, structures, materials or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present disclosure. The schematic representation of the above terms does not necessarily refer to the same embodiment or example. In addition, the particular features, structures, materials or characteristics may be included in any one or more embodiments or examples in any appropriate manner.

[0048] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of some embodiments of the present disclosure, unless otherwise specified, "plurality" means two or more.

[0049] When describing some embodiments, the expressions "coupled" and "connected" and their derivatives may be used. The term "connected" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. The term "coupled" indicates, for example, that two or more components are in direct physical or electrical contact. The term "coupled" or "communicatively coupled" may also refer to two or more components that are not in direct contact with each other, but still cooperate or interact with each other. The embodiments disclosed herein are not necessarily limited to the contents of this document.

[0050] “A and / or B” includes the following three combinations: A only, B only, and a combination of A and B.

[0051] The use of "adapted to" or "configured to" herein is intended to be open and inclusive language that does not exclude devices adapted or configured to perform additional tasks or steps.

[0052] Additionally, the use of “based on” is meant to be open and inclusive, as a process, step, calculation, or other action “based on” one or more stated conditions or values ​​may, in practice, be based on additional conditions or values ​​beyond those stated.

[0053] When an air conditioning system is operating in heating mode, frost may form on the outdoor heat exchanger components when the ambient temperature and humidity reach certain levels. This can reduce the system's heating performance and heat output, impacting the user experience. Following this frost, the system initiates a defrost process to defrost the outdoor heat exchanger components. Currently, there are two main methods for achieving this.

[0054] In the first implementation, the air-conditioning system uses a reverse defrost method to defrost the outdoor heat exchanger assembly. By reversing the flow of the refrigerant in heating, the refrigerant discharged from the compressor is supplied to the outdoor heat exchanger assembly, and the heat of the compressor is used to defrost the outdoor heat exchanger assembly. During reverse defrosting, the air-conditioning system stops heating the room, and the indoor heat exchanger is required to absorb some heat from the room, which lowers the indoor temperature, affects the indoor thermal comfort, and reduces the user experience. In addition, the reverse defrost method also requires changing the refrigerant flow direction, especially when switching to heating mode after defrosting. Since a large amount of refrigerant is stored in the gas-liquid separator during the defrosting process, after defrosting, the pressure difference between the high pressure at the exhaust port and the low pressure at the intake port is slowly established when the compressor starts, which leads to a decrease in the heating capacity of the air-conditioning system, affecting the real-time heating capacity and the indoor thermal comfort.

[0055] In the second implementation, the air conditioning system uses a bypass to defrost the outdoor heat exchanger assembly. This bypass is installed in the compressor exhaust pipe and connected to the outdoor heat exchanger intake pipe. When defrosting is required, the refrigerant discharged from the compressor enters the outdoor heat exchanger assembly through the bypass to defrost it. However, this defrosting method uses heat solely from the compressor's compression power, resulting in poor defrosting reliability and prolonged defrosting time.

[0056] In the above two implementation methods, when the air-conditioning system is defrosting, the indoor heating amount will be reduced, affecting the thermal comfort of indoor users.

[0057] Based on this, the present disclosure provides an air conditioning system capable of operating in a defrost-free mode. This mode prevents frost formation on outdoor heat exchanger components and allows the indoor heat exchanger to continue heating the room without interruption, eliminating the need to defrost outdoor components. The air conditioning system provided by the present disclosure is described in detail below.

[0058] As shown in Figures 1 and 2, some embodiments of the present disclosure provide an air conditioning system 100 including an indoor unit 10, an outdoor unit 20, and a controller 40. The indoor unit 10 includes an indoor heat exchanger 101, and the outdoor unit 20 includes a compressor 21, an outdoor fan 22, an outdoor heat exchanger assembly 3, and a first branch 41.

[0059] For example, the air conditioning system 100 may include one or more indoor units 10 and one or more outdoor units 20 .

[0060] For example, in FIG1 , the air conditioning system 100 includes two indoor units 10 and one outdoor unit 20. In FIG3 , the air conditioning system 100 includes one indoor unit 10 and two outdoor units 20.

[0061] For example, when the air conditioning system 100 includes a plurality of indoor units 10, the first ends of the plurality of indoor units 10 are connected to each other, and the second ends of the plurality of indoor units 10 are connected to each other. When the air conditioning system 100 includes a plurality of outdoor units 20, the first ends of the plurality of outdoor units 20 are connected to each other, and the second ends of the plurality of outdoor units 20 are connected to each other.

[0062] For example, when the air conditioning system 100 includes one or more indoor heat exchangers 101 , each indoor unit includes one indoor heat exchanger 101 .

[0063] As shown in FIG3 , the compressor 21 has an air intake port 211 and an air exhaust port 212. For example, the air intake port 211 of the compressor 21 is configured to inhale air, and the refrigerant enters the compression chamber of the compressor 21 through the air intake port 211 and is compressed to form a high-temperature and high-pressure refrigerant. The high-temperature and high-pressure refrigerant gas then exits the compressor 21 through the air exhaust port 212 of the compressor 21 and enters the air conditioning system 100 for refrigerant circulation.

[0064] For example, each outdoor unit 20 includes one or more compressors 21 .

[0065] For example, the compressor 21 may be a scroll compressor, a rotary compressor, a screw compressor, or another type of compressor.

[0066] For example, the outdoor fan 22 is configured to increase the flow speed of the air around the outdoor heat exchanger assembly 3 and increase the heat exchange speed between the outdoor heat exchanger assembly 3 and the surrounding air.

[0067] For example, the outdoor heat exchanger assembly 3 is configured to exchange heat with outdoor air.

[0068] In some embodiments, as shown in FIG3 , the outdoor heat exchanger assembly 3 includes a first portion 31 and a second portion 32 , and the second portion 32 and the first portion 31 are sequentially arranged along the direction of the airflow formed when the outdoor fan 22 is working.

[0069] For example, the first portion 31 and the second portion 32 are two independent heat exchangers. When the air conditioning system 100 is operating in cooling or heating mode, the air conditioning system can be prevented from shutting down due to damage to one of the first portion 31 and the second portion 32, thereby improving the stability and reliability of the operation of the air conditioning system 100. Alternatively, the first portion 31 and the second portion 32 can be two parts of the same heat exchanger. This facilitates the transportation and assembly of the air conditioning system 100, thereby improving the assembly efficiency of the air conditioning system 100.

[0070] For example, the first portion 31 is located on one side of the second portion 32, and in a plane perpendicular to the direction from the first portion 31 to the second portion 32, the projections of at least a portion of the first portion 31 and at least a portion of the second portion 32 overlap. The second portion 32 is configured to exchange heat with the first portion 31. It is understood that the second portion 32 can transfer heat to the first portion 31.

[0071] For example, the first portion 31 and the second portion 32 can be arranged along the horizontal direction. For example, the first portion 31 is located to one side of the second portion 32 in the horizontal direction. For example, in a vertical plane perpendicular to the horizontal direction, the projection of the first portion 31 is located within the projection of the second portion 32. For example, in a vertical plane perpendicular to the horizontal direction, the projection of the second portion 32 is located within the projection of the second portion 31. For example, in a vertical plane perpendicular to the horizontal direction, the projection of the first portion 31 coincides with the projection of the second portion 32. For example, the spacing distance between the first portion 31 and the second portion 32 is L, 0≤L<L1. L1 is the maximum spatial distance within the internal space of the outdoor unit 20.

[0072] For example, as shown in FIG3 , the direction of the airflow formed when the outdoor fan 22 is working is the direction of the arrow in the figure (horizontal direction). The airflow formed when the outdoor fan 22 is working first blows toward the second part 32 and then blows toward the first part 31 .

[0073] For example, when the outdoor heat exchanger assembly 3 includes three rows of heat exchange pipes, the outermost row of heat exchange pipes can be used as the second part 32, and the middle row of heat exchange pipes and the innermost row of heat exchange pipes can be used as the first part 31.

[0074] Through the above arrangement, the airflow formed when the outdoor fan 22 is in operation first exchanges heat with the second part 32 and then exchanges heat with the first part 31 .

[0075] For example, the first portion 31 and the second portion 32 may be arranged along a vertical direction. For example, the first portion 31 is located to one side of the second portion 32 in the vertical direction. For example, in a horizontal plane perpendicular to the vertical direction, the projection of the first portion 31 is located within the projection of the second portion 32. For example, in a horizontal plane perpendicular to the vertical direction, the projection of the second portion 32 is located within the projection of the second portion 31. For example, in a horizontal plane perpendicular to the vertical direction, the projection of the first portion 31 and the projection of the second portion 32 overlap.

[0076] As shown in Figures 4 and 5, in some embodiments, the first portion 31 is located above the second portion 32. Thus, during the defrosting process of the outdoor heat exchanger assembly 3, the first portion 31 can be defrosted first, and then the second portion 32. Heat from the first portion 31 can be transferred to the second portion 32 via defrosting water, melting some of the ice, thereby accelerating the defrosting of the outdoor heat exchanger assembly 3.

[0077] As shown in Figures 6 and 7, in some embodiments, the second portion 32 is located above the first portion 31. Thus, during the defrosting process of the outdoor heat exchanger assembly 3, the second portion 32 can be defrosted first, followed by the first portion 31. Heat from the second portion 32 can be transferred to the first portion 31 via the defrosting water, melting some of the ice, thereby accelerating the defrosting of the outdoor heat exchanger assembly 3.

[0078] It should be noted that the up and down directions here are consistent with the up and down directions of the air conditioning system 100 when it is installed and in use.

[0079] In some examples, as shown in Figures 3 and 4, the first end of the first branch 41 is connected to the first end of the second portion 32, and the second end of the first branch 41 is connected to the second end of the first portion 31. A first throttle valve 51 is provided on the first branch 41 and is connected to the first branch.

[0080] The first throttle valve 51 is configured to control the on-off of the first branch 41, and to throttle and reduce the pressure of the refrigerant flowing through the first throttle valve 51. That is, the opening of the first throttle valve 51 is adjustable. The first throttle valve 51 can be adjusted to a fully open state (i.e., the opening of the first throttle valve 51 is 100%), a fully closed state (i.e., the opening of the first throttle valve 51 is 0) and a throttling state (i.e., the opening of the first throttle valve 51 is between 0 and 100%). When the first throttle valve 51 is in a fully closed state, there is no conduction between the pipelines at both ends of the first throttle valve 51. When the first throttle valve 51 is in a fully open state and a throttling state, there is conduction between the pipelines at both ends of the first throttle valve 51. And the first throttle valve 51 can throttle and reduce the pressure of the refrigerant flowing through the first throttle valve 51 in the throttling state.

[0081] For example, the first throttle valve 51 may be an electronic expansion valve; or, the first throttle valve 51 may also be a thermal expansion valve.

[0082] Through the above arrangement, the first end of the second part 32 and the second end of the first part 31 can be connected through the first branch 41, and the communication between the first end of the second part 32 and the second end of the first part 31 can be controlled by the first throttle valve 51.

[0083] In some examples, as shown in FIG3 , when the outdoor unit 20 is operating in the defrost-free mode, the first end of the indoor heat exchanger 101 is in communication with the exhaust port 212 of the compressor 21, the second end of the indoor heat exchanger 101 is in communication with the second end of the second portion 32, and the first end of the first portion 31 is in communication with the intake port 211 of the compressor 21. This allows the refrigerant in the compressor 21 to sequentially enter the indoor heat exchanger 101 and the second portion 32 from the exhaust port 212, heat the second portion 32, and ultimately return to the compressor 21 through the first portion 31 and the intake port 211. The outdoor fan 22 operates to blow the heated air near the second portion 32 toward the first portion.

[0084] Through the above arrangement, the waste heat in the refrigerant flowing from the indoor heat exchanger 101 to the second portion 32 can be used to heat the second portion 32, thereby preventing frost on the second portion 32. The heated second portion 32 can heat the surrounding air, increasing the temperature of the surrounding air. After the outdoor fan 22 is activated, the hot air around the second portion 32 can be blown toward the first portion 31, thereby heating the first portion 31 and preventing frost on the first portion 31. At the same time, the heated second portion 32 can also heat the first portion 31 through heat conduction and heat radiation between the pipes, thereby preventing frost on the first portion 31.

[0085] Thus, by operating in defrost-free mode, the air conditioning system 100 can prevent frost formation on the outdoor heat exchanger assembly 3. Furthermore, after the temperature of the first portion 31 rises, the evaporation capacity of the refrigerant in the first portion 31 can be increased. This improves the heating capacity of the air conditioning system 100 and enhances the reliability of the compressor and the air conditioning system 100. At the same time, the indoor unit 10 can continuously heat the room, improving the thermal comfort of indoor users and, in turn, enhancing the user experience.

[0086] In some embodiments, as shown in FIG. 3 to FIG. 5 , the outdoor unit 20 further includes a reversing assembly 6 .

[0087] The reversing assembly 6 is configured to adjust the flow direction of the refrigerant in the air-conditioning system 100 .

[0088] In some embodiments, as shown in Figures 3 to 5, the reversing assembly 6 includes a first valve port 61, a second valve port 62, a third valve port 63, and a fourth valve port 64. The first valve port 61 is in communication with the exhaust port 212; the second valve port 62 is in communication with the first end of the indoor heat exchanger 101; the third valve port 63 is in communication with the first end of the first portion 31 and the first end of the second portion 32; and the fourth valve port 64 is in communication with the intake port 211.

[0089] As shown in FIG3 , the first valve port 61 can be switched to communicate with one of the second valve port 62 and the third valve port 63, and the fourth valve port 64 can be switched to communicate with the other of the second valve port 62 and the third valve port 63. That is, when the first valve port 61 is in communication with the second valve port 62, the third valve port 63 is in communication with the fourth valve port 64; and when the first valve port 61 is in communication with the third valve port 63, the second valve port 62 is in communication with the fourth valve port 64.

[0090] In some embodiments, the reversing assembly 6 may be a four-way reversing valve. The four-way reversing valve can switch between an open and a closed state. When the four-way reversing valve is powered on, the four-way reversing valve is open, the first valve port 61 is connected to the second valve port 62, and the third valve port 63 is connected to the fourth valve port 64. When the four-way reversing valve is powered off, the four-way reversing valve is closed, the first valve port 61 is connected to the third valve port 63, and the second valve port 62 is connected to the fourth valve port 64.

[0091] In some embodiments, when the power is turned off to the four-way reversing valve, the first valve port 61 is connected to the second valve port 62, and the third valve port 63 is connected to the fourth valve port 64; when the power is turned on to the four-way reversing valve, the first valve port 61 is connected to the third valve port 63, and the second valve port 62 is connected to the fourth valve port 64.

[0092] In some examples, as shown in Figures 3 to 5, the outdoor unit 20 further includes a second branch 42. A first end of the second branch 42 is in communication with a second end of the first portion 31, and a second end of the second branch 42 is in communication with a second end of the indoor heat exchanger 101. A second throttle valve 52 is provided on the second branch 42, and the second throttle valve 52 is in communication with the second branch.

[0093] The second throttle valve 52 is configured to control the on-off of the second branch 42 and to throttle and reduce the pressure of the refrigerant flowing through the second throttle valve 52. That is, the opening of the second throttle valve 52 is adjustable. The second throttle valve 52 can be adjusted to a fully open state (i.e., the opening of the second throttle valve 52 is 100%), a fully closed state (i.e., the opening of the second throttle valve 52 is 0) and a throttling state (i.e., the opening of the second throttle valve 52 is between 0 and 100%). When the second throttle valve 52 is in a fully closed state, there is no conduction between the pipelines at both ends of the second throttle valve 52. When the second throttle valve 52 is in a fully open state and a throttling state, there is conduction between the pipelines at both ends of the second throttle valve 52, and the second throttle valve 52 can throttle and reduce the pressure of the refrigerant flowing through the second throttle valve 52 when it is in a throttling state.

[0094] In some examples, the outdoor unit 20 further includes a third branch 43. A first end of the third branch 43 is connected to the second end of the second portion 32, and a second end of the third branch 43 is connected to the second end of the indoor heat exchanger 101. A third throttle valve 53 is provided on the third branch 43 and is in communication with the third branch 43.

[0095] The third throttle valve 53 is configured to control the on-off of the third branch 43 and to throttle and reduce the pressure of the refrigerant flowing through the third throttle valve 53. That is, the opening of the third throttle valve 53 is adjustable. The third throttle valve 53 can be adjusted to a fully open state (i.e., the opening of the third throttle valve 53 is 100%), a fully closed state (i.e., the opening of the third throttle valve 53 is 0) and a throttle state (i.e., the opening of the third throttle valve 53 is between 0 and 100%). When the third throttle valve 53 is in a fully closed state, there is no conduction between the pipelines at both ends of the third throttle valve 53. When the third throttle valve 53 is in a fully open state and a throttle state, there is conduction between the pipelines at both ends of the third throttle valve 53, and when the third throttle valve 53 is in a throttle state, the refrigerant flowing through the third throttle valve 53 can be throttled and reduced in pressure.

[0096] In some embodiments, as shown in FIG. 3 to FIG. 5 , the third valve port 63 is connected to the first end of the second portion 32 and a second on-off valve 54 is provided on the connecting pipeline.

[0097] For example, the second on-off valve 54 can be a two-way valve. For example, the second on-off valve 54 can be a solenoid valve or a throttle valve. For example, the second on-off valve 54 can be an electronic expansion valve. For example, the second on-off valve 54 can be a reversible two-way valve. The second on-off valve 54 is configured to switch between an open state and a closed state to control the flow of the pipeline between the third valve port 63 and the first end of the second portion 32.

[0098] For example, the second throttle valve 52 and the third throttle valve 53 may both be electronic expansion valves; or, the second throttle valve 52 and the third throttle valve 53 may both be thermal expansion valves.

[0099] The air conditioning system 100 provided in some embodiments of the present disclosure has fewer valves and connecting pipes, a simple structure, and low cost.

[0100] In some embodiments, as shown in FIG. 3 to FIG. 5 , the indoor unit 10 further includes an indoor fan 102 .

[0101] The indoor fan 102 is configured to increase the heat exchange rate of the indoor heat exchanger 101 .

[0102] In some embodiments, the air conditioning system 100 has a cooling mode, a heating mode, and a defrost-free mode. The following describes in detail the control process and refrigerant flow direction of the cooling mode, heating mode, and defrost-free mode of the air conditioning system in this embodiment.

[0103] <Cooling Mode>

[0104] Referring to FIG. 8 , when the air conditioning system 100 operates in cooling mode, the controller 40 controls the first valve port 61 of the reversing assembly 6 to communicate with the third valve port 63, and the second valve port 62 to communicate with the fourth valve port 64. The controller 40 controls the first throttle valve 51 to be fully closed, the second throttle valve 52 to be throttled, to control the degree of subcooling at the outlet of the first portion 31, and the third throttle valve 53 to be throttled, to control the degree of subcooling at the outlet of the second portion 32. The second on-off valve 54 is switched to an open state, and the outdoor fan 22 operates.

[0105] In this case, the high-temperature, high-pressure gaseous refrigerant discharged from the exhaust port 212 of the compressor 21 flows into the reversing assembly 6 through the first valve port 61 and flows out of the reversing assembly 6 through the third valve port 63. The refrigerant flowing out of the third valve port 63 flows to the first portion 31 and the second portion 32, and after sufficient heat exchange in the first portion 31 and the second portion 32, it becomes a high-pressure, medium-temperature liquid refrigerant. The refrigerant flowing out of the first portion 31 and the second portion 32 then flows through the second throttle valve 52 and the third throttle valve 53, and after being throttled by the second throttle valve 52 and the third throttle valve 53, it becomes a low-temperature, low-pressure two-phase refrigerant. The two-phase refrigerant after throttling and reducing the pressure through the second throttle valve 52 and the third throttle valve 53 flows into the indoor heat exchanger 101, and is evaporated into a low-temperature and low-pressure gaseous refrigerant in the indoor heat exchanger 101 to cool the indoor environment. Finally, the low-temperature and low-pressure gaseous refrigerant flows back to the intake port 211 of the compressor 21 through the second valve port 62 and the fourth valve port 64 in turn, thereby completing the refrigeration cycle of the air-conditioning system 100.

[0106] <Heating Mode>

[0107] Referring to Figure 9 , when the air conditioning system 100 operates in heating mode, the controller 40 controls the first valve port 61 of the reversing assembly 6 to communicate with the second valve port 62, and with the third valve port 63 and fourth valve port 64. The controller 40 controls the first throttle valve 51 to be fully closed, the second throttle valve 52 to be throttled, and the third throttle valve 53 to be throttled to control the intake and exhaust superheat of the compressor 21. The second on-off valve 54 is switched to the open state, and the outdoor fan 22 operates.

[0108] In this case, the high-temperature, high-pressure gaseous refrigerant discharged from the exhaust port 212 of the compressor 21 flows into the reversing assembly 6 through the first valve port 61 and flows out of the reversing assembly 6 through the second valve port 62. The refrigerant flowing out of the second valve port 62 flows to the indoor heat exchanger 101. After heat exchange in the indoor heat exchanger 101, the refrigerant flowing out of the second valve port 62 is cooled into a high-pressure, medium-temperature liquid refrigerant to heat the room. Then, the high-pressure, medium-temperature liquid refrigerant flows out of the indoor heat exchanger 101 and flows to the second throttle valve 52 and the third throttle valve 53. After being throttled by the second throttle valve 52 and the third throttle valve 53, it flows into the first part 31 and the second part 32 respectively, and is evaporated into a low-temperature, low-pressure gaseous refrigerant in the first part 31 and the second part 32. Finally, the low-temperature and low-pressure gaseous refrigerant flows out from the first portion 31 and the second portion 32 and flows back to the air intake 211 of the compressor 21 through the third valve port 63 and the fourth valve port 64 in sequence, thus completing the heating cycle of the air-conditioning system 100.

[0109] <Defrost-free mode>

[0110] Referring to Figure 10 , when the air conditioning system 100 operates in defrost-free mode, the refrigerant in the outdoor unit 20 heats the second portion 32, and in this case, the second portion 32 heats the first portion 31. The controller 40 controls the first valve port 61 of the reversing assembly 6 to communicate with the second valve port 62, and with the third valve port 63 and fourth valve port 64. The controller 40 controls the first throttle valve 51 to a throttled state to control the suction / discharge superheat of the compressor 21, the second throttle valve 52 to a fully closed state, the third throttle valve 53 to a fully open state, and the second on-off valve 54 to a closed state, thereby operating the outdoor fan 22.

[0111] It is understandable that when the air-conditioning system 100 includes multiple outdoor units 20 , the above operation can be performed on one of the outdoor units 20 while the remaining outdoor units 20 maintain their original working state, or the above operation can be performed on all the outdoor units 20 .

[0112] In this case, the high-temperature, high-pressure gaseous refrigerant discharged from the exhaust port 212 of the compressor 21 flows through the first valve port 61 into the reversing assembly 6 and out of the reversing assembly 6 through the second valve port 62. The refrigerant flowing out of the second valve port 62 flows to the indoor heat exchanger 101, where it undergoes heat exchange and is cooled to a high-pressure, medium-temperature liquid refrigerant to heat the room. The high-pressure, medium-temperature liquid refrigerant then flows from the indoor heat exchanger 101 to the third throttle valve 53. After passing through the third throttle valve 53, it flows into the second portion 32. The waste heat of the high-pressure, medium-temperature liquid refrigerant heats the second portion 32. The refrigerant flowing out of the second portion 32 is throttled by the first throttle valve 51 and flows to the first portion 31, where it evaporates into a low-temperature, low-pressure gaseous refrigerant. Finally, the low-temperature, low-pressure gaseous refrigerant flows out of the first portion 31 and, sequentially, through the third valve port 63 and the fourth valve port 64, flows back to the intake port 211 of the compressor 21.

[0113] During the above process, the heated second portion 32 can heat the surrounding air, raising its temperature. When the outdoor fan 22 is activated, the hot air surrounding the second portion 32 is blown toward the first portion 31, thereby heating the first portion 31 and preventing frost on the first portion 31. Simultaneously, the heated second portion 32 can also heat the first portion 31 through heat conduction and radiation between the pipes, thereby preventing frost on the first portion 31. Therefore, the air conditioning system 100 can prevent frost on the outdoor heat exchanger assembly 3, improve the system's heating capacity, and enhance the reliability of the compressor and system. Furthermore, during the above process, the indoor unit 10 can continuously heat the room, improving the thermal comfort and user experience of the indoor users.

[0114] In some embodiments, as shown in FIG11 , the outdoor unit 20 of the air conditioning system 100 further includes a fourth branch 44. A first end of the fourth branch 44 communicates with the exhaust port 212 of the compressor 21, and a second end of the fourth branch 44 communicates with the second end of the first portion 31. A first on-off valve 55 is disposed on the fourth branch 44 and communicates with the first on-off valve 55. For example, when the air conditioning system 100 is operating in defrost mode, the fourth branch 44 is configured to allow the refrigerant in the compressor 21 to enter the first portion 31 through the exhaust port 212 to heat the first portion 31, and ultimately return to the compressor 21 through the intake port 211.

[0115] For example, the first on-off valve 55 may be a two-way valve. For example, the first on-off valve 55 may be a solenoid valve or a throttle valve. For example, the first on-off valve 55 may be an electronic expansion valve. For example, the first on-off valve 55 may be a reversible two-way valve. The first on-off valve 55 is configured to switch between an open state and a closed state to control the on / off of the fourth branch 44.

[0116] Through the above-mentioned arrangement, the first part 31 can be heated directly by the refrigerant discharged from the compressor 21 on the basis of heating the first part 31 through the second part 32, which is beneficial to increasing the heating rate of the first part 31. In the case of frost on the first part 31, the defrosting speed can be increased.

[0117] In some embodiments, the air conditioning system 100 also has a defrost mode. If frost forms on the outdoor heat exchanger assembly, the air conditioning system 100 can utilize the heat from the refrigerant discharged by the compressor 21 to defrost the outdoor heat exchanger assembly while operating in defrost mode. The following describes in detail the control process and refrigerant flow direction for the cooling mode, heating mode, defrost-free mode, and defrost mode of the air conditioning system provided in some embodiments of the present disclosure.

[0118] <Cooling Mode>

[0119] 12 , unlike the air conditioning system 100 of some embodiments shown in FIG8 , the air conditioning system 100 provided in some embodiments of the present disclosure further includes a first on-off valve 55. When the air conditioning system 100 operates in cooling mode, the controller 40 controls the first on-off valve 55 to switch to a closed state.

[0120] The refrigerant flow direction is the same as the refrigerant flow direction in the cooling mode of the air-conditioning system 100 of some embodiments shown in FIG8 , and will not be described in detail here.

[0121] <Heating Mode>

[0122] 13 , unlike the air conditioning system 100 of some embodiments shown in FIG9 , the air conditioning system 100 provided in some embodiments of the present disclosure further includes a first on-off valve 55. When the air conditioning system 100 operates in heating mode, the controller 40 controls the first on-off valve 55 to switch to a closed state.

[0123] The refrigerant flow direction is the same as the refrigerant flow direction in the heating mode of the air-conditioning system 100 of some embodiments shown in FIG. 9 , and will not be described in detail here.

[0124] <Defrost-free mode>

[0125] 14 , unlike the air conditioning system 100 of some embodiments shown in FIG10 , the air conditioning system 100 provided in some embodiments of the present disclosure further includes a first on-off valve 55. When the air conditioning system 100 operates in the defrost-free mode, the controller 40 switches the first on-off valve 55 to a closed state.

[0126] The refrigerant flow direction is the same as that in the defrost-free mode of the air-conditioning system 100 of some embodiments shown in FIG. 10 , and will not be described in detail here.

[0127] In some examples, air conditioning system 100 may also operate in a defrost mode.

[0128] Referring to Figure 15 , when air conditioning system 100 operates in defrost mode, in outdoor unit 20, a portion of the refrigerant flowing out of compressor 21 can flow through fourth branch 44 and directly heat first portion 31. Controller 40 controls the first valve port 61 of reversing assembly 6 to communicate with the second valve port 62, and with the third valve port 63 and fourth valve port 64. Controller 40 controls first throttle valve 51 to fully close, second throttle valve 52 to fully close, and third throttle valve 53 to a throttled state to control the intake and exhaust superheat of compressor 21. Second on-off valve 54 and first on-off valve 55 are switched to an open state, and outdoor fan 22 operates.

[0129] In this case, a portion of the high-temperature, high-pressure gaseous refrigerant discharged from the exhaust port 212 of the compressor 21 flows into the reversing assembly 6 through the first valve port 61 and flows out of the reversing assembly 6 through the second valve port 62. The refrigerant flowing out of the second valve port 62 flows to the indoor heat exchanger 101, and after heat exchange in the indoor heat exchanger 101, it is cooled into a high-pressure, medium-temperature liquid refrigerant to heat the room. Then, the high-pressure, medium-temperature liquid refrigerant flows from the indoor heat exchanger 101 to the third throttle valve 53, is throttled by the third throttle valve 53, and flows into the second part 32, where it is evaporated into a low-temperature, low-pressure gaseous refrigerant. Finally, the low-temperature, low-pressure gaseous refrigerant flows out of the second part 32 and flows back to the intake port 211 of the compressor 21 through the second on-off valve 54, the third valve port 63, and the fourth valve port 64 in sequence. Another portion of the high-temperature, high-pressure gaseous refrigerant discharged from the exhaust port 212 of the compressor 21 flows into the first portion 31 through the fourth branch 44 and the first on-off valve 55. The refrigerant flowing out of the first portion 31 flows back to the intake port 211 of the compressor 21 through the second on-off valve 54, the third valve port 63, and the fourth valve port 64 in sequence.

[0130] Through the above-mentioned arrangement, the first part 31 can be directly heated by utilizing the sensible high temperature of the refrigerant discharged from the compressor 21. In this way, the heating speed of the first part 31 can be accelerated, and the temperature of the first part 31 can be rapidly increased. In the case where thick frost forms on the first part 31, the defrosting speed of the first part 31 can be accelerated.

[0131] 4 and 6 , the outdoor unit 20 further includes a fifth branch 45. A first end of the fifth branch 45 is connected to the exhaust port, and a second end of the fifth branch 45 is connected to the second end of the second portion 32. A throttling assembly 56 is connected in series to the fifth branch 45.

[0132] In some embodiments, the throttling component 56 is configured to control the on-off of the fifth branch 45 and to throttle and reduce the pressure of the refrigerant flowing through the fifth branch 45. That is, the opening of the throttling component 56 is adjustable. The throttling component 56 can be adjusted to a fully open state (i.e., the opening of the throttling component 56 is 100%), a fully closed state (i.e., the opening of the throttling component 56 is 0) and a throttling state (i.e., the opening of the throttling component 56 is between 0 and 100%). When the throttling component 56 is in a fully closed state, there is no conduction between the pipelines at both ends of the third throttle valve 53. When the throttling component 56 is in a fully open state and a throttling state, there is conduction between the pipelines at both ends of the throttling component 56, and when the throttling component 56 is in a throttling state, the refrigerant flowing through the throttling component 56 can be throttled and reduced in pressure.

[0133] 4 to 7 , in some embodiments, the throttling component 56 includes a throttling valve. For example, the throttling component 56 may include an electronic expansion valve, thereby improving the operating speed and control accuracy of the air conditioning system 100.

[0134] When the air-conditioning system 100 operates in cooling mode or heating mode, the second end of the second part 32 is the liquid inlet end, and the second end of the fifth branch 45 is connected to the liquid inlet end of the second part 32. In this way, the pipeline distribution and connection structure between the fifth branch 45 and the second part 32 can be simplified, which facilitates the assembly of the air-conditioning system.

[0135] For example, the second end of the fifth branch 45 is connected to the pipeline between the third throttle valve 53 and the second portion 32. This allows the refrigerant in the fifth branch 45 to bypass the third throttle valve 53 and directly enter the second portion 32, preventing the third throttle valve 53 from affecting the state of the refrigerant in the fifth branch 45. When frost forms on the second portion 32, the throttle assembly 56 can be controlled so that the high-temperature, high-pressure gaseous refrigerant discharged from the exhaust port 212, after being throttled and reduced in pressure by the throttle assembly 56 and converted into liquid refrigerant, can then enter the second portion 32 along the fifth branch 45, thereby utilizing the latent heat of the exhaust gas from the compressor 21 to defrost the second portion 32. When defrosting of the second portion 32 is not necessary, the throttle assembly 56 can be fully closed, preventing the high-temperature, high-pressure gaseous refrigerant discharged from the exhaust port 212 from flowing into the fifth branch 45 and affecting the operation of the air conditioning system 100, thereby improving the reliability of the air conditioning system 100.

[0136] In some embodiments, the throttle assembly 56 is configured to control the on / off of the fifth branch 45. For example, the throttle assembly 56 includes a third on / off valve and a pressure reducer connected in series, which helps reduce the manufacturing difficulty and cost of the throttle assembly 56 and facilitates maintenance.

[0137] In some embodiments, as shown in Figures 5 and 7 , the first end of the fifth branch 45 is connected to the exhaust port, the first end of the first branch 41 is connected to the pipeline between the second throttle valve 52 and the second end of the first portion 31. The second end of the fifth branch 45 is connected to the pipeline between the first end of the second portion 32 and the second on-off valve 54, and the second end of the first branch 41 is connected to the second end of the second portion 32. The second end of the fifth branch 45 is connected to the intake end of the second portion 32. This reduces the pressure drop of the fifth branch 45, allowing for a smaller throttle assembly 56, thereby reducing the cost of the air conditioning system 100.

[0138] For example, the second end of the first branch 41 is connected to the pipeline between the second end of the second part 32 and the third throttle valve 53. The principle and effect are similar to the embodiments shown in Figures 4 and 6 and are not repeated here.

[0139] In some embodiments, the air conditioning system 100 has a cooling mode, a heating mode, and a defrost mode.

[0140] <Cooling Mode>

[0141] 16 and 17 , unlike the air conditioning system 100 of some embodiments shown in FIG12 , the air conditioning system 100 provided in some embodiments of the present disclosure further includes a throttle assembly 56. When the air conditioning system 100 operates in cooling mode, the controller 40 controls the throttle assembly 56 to be fully closed.

[0142] The refrigerant flow direction is the same as the refrigerant flow direction in the cooling mode of the air-conditioning system 100 of some embodiments shown in FIG. 12 , and will not be described in detail here.

[0143] <Heating Mode>

[0144] 18 and 19 , unlike the air conditioning system 100 of some embodiments shown in FIG13 , the air conditioning system 100 provided in some embodiments of the present disclosure further includes a throttling assembly 56. When the air conditioning system 100 operates in heating mode, the controller 40 controls the first on-off valve 55 to switch to a closed state.

[0145] The refrigerant flow direction is the same as the refrigerant flow direction in the heating mode of the air-conditioning system 100 of some embodiments shown in FIG. 13 , and will not be described in detail here.

[0146] <Defrost mode>

[0147] 20 and 21 , unlike the air conditioning system 100 of some embodiments shown in FIG15 , the air conditioning system 100 provided in some embodiments of the present disclosure further includes a throttle assembly 56. When defrosting the first portion 31, the controller 40 controls the throttle assembly 56 to be fully closed.

[0148] The refrigerant flow direction is the same as the refrigerant flow direction in the defrost mode of the air-conditioning system 100 of some embodiments shown in FIG. 15 , and will not be described in detail here.

[0149] In some embodiments, referring to Figures 22 and 23 , when defrosting the second portion 32, the controller 40 controls the first valve port 61 of the reversing assembly 6 to communicate with the second valve port 62, and the third valve port 63 to communicate with the fourth valve port 64. The controller 40 controls the second on-off valve 54 to switch to a closed state, the second throttle valve 52 to a throttle state, the third throttle valve 53 to a closed state, the throttle assembly 56 to a throttle state, the first on-off valve 55 to switch to a closed state, and the first throttle valve 51 to a throttle state.

[0150] In this case, the high-temperature, high-pressure gaseous refrigerant discharged from the exhaust port 212 of the compressor 21 flows to the reversing assembly 6 and the fifth branch 45, respectively. The refrigerant flowing to the reversing assembly 6 flows into the reversing assembly 6 through the first valve port 61 and flows out of the reversing assembly 6 from the second valve port 62. The refrigerant flowing out of the second valve port 62 flows to the indoor heat exchanger 101. The high-temperature, high-pressure gaseous refrigerant flowing to the indoor heat exchanger 101 is condensed into a high-temperature, high-pressure subcooled liquid refrigerant after heat exchange in the indoor heat exchanger 101. Then, the high-temperature, high-pressure subcooled liquid refrigerant flowing out of the indoor heat exchanger 101 flows to the second throttle valve 52, and after being throttled in the second throttle valve 52, it becomes a low-temperature, low-pressure two-phase refrigerant. Next, the low-temperature, low-pressure two-phase refrigerant flows to the first part 31, and after evaporating in the first part 31, it becomes a low-temperature, low-pressure gaseous refrigerant.

[0151] The high-temperature, high-pressure gaseous refrigerant flowing into the fifth branch 45 is throttled by the throttling assembly 56 and converted into a high-temperature, medium-pressure gaseous refrigerant, which then flows into the second portion 422. The high-temperature, medium-pressure gaseous refrigerant is condensed in the second portion 422 and converted into a medium-temperature, medium-pressure liquid refrigerant, which then flows into the first branch 41. After being throttled by the first throttle valve 51, it becomes a low-temperature, low-pressure liquid refrigerant, which merges with the low-temperature, low-pressure refrigerant from the indoor heat exchanger 101 and then flows into the first portion 421. In the first portion 31, the merged refrigerants are evaporated and converted into a low-temperature, low-pressure gaseous refrigerant. The refrigerant then flows back to the intake port 211 of the compressor 21 through the third valve port 63 and the fourth valve port 64, completing the defrost refrigerant cycle for the second portion 32.

[0152] It can be understood that the air-conditioning system 100 provided in some embodiments of the present disclosure includes a first defrost flow path formed by connecting the exhaust port 212, the fourth branch 44, the first part 31 and the intake port 211 of an outdoor unit 20 in sequence, a second defrost flow path formed by connecting the exhaust port 212, the fifth branch 45, the second part 32, the first branch 41, the first part 31 and the intake port 211 in sequence, and a third defrost flow path formed by connecting the exhaust port 212, the fifth branch 45, the second part 32 and the intake port 301 in sequence.

[0153] Therefore, in some embodiments, the air conditioning system 100 can defrost the first portion 31 through the first defrost flow path by utilizing the sensible heat of a portion of the high-temperature, high-pressure gaseous refrigerant from the compressor 21. In this case, the first portion 31 functions as a condenser, the second portion 32 can function as an evaporator, and the indoor heat exchanger 101 can utilize another portion of the high-temperature, high-pressure gaseous refrigerant from the compressor 21 to heat the indoor air.

[0154] In some embodiments, the air conditioning system 100 can defrost the second portion 32 through the third defrost flow path, utilizing the sensible heat of a portion of the high-temperature, high-pressure gaseous refrigerant from the compressor 21. In this case, the second portion 32 functions as a condenser, the first portion 31 can function as an evaporator, and the indoor heat exchanger 101 can utilize another portion of the high-temperature, high-pressure gaseous refrigerant from the compressor 21 to heat the indoor air.

[0155] In some embodiments, the air conditioning system 100 can defrost the second portion 32 by controlling the opening of the throttle assembly 56 and the first throttle valve 51 on the second defrost flow path and utilizing the latent heat of the high-temperature, high-pressure gaseous refrigerant from the compressor 21. The refrigerant releases more heat and the defrosting speed is fast. In this case, the second portion 32 acts as a condenser, the first portion 31 can act as an evaporator, and the indoor heat exchanger 101 can utilize another portion of the high-temperature, high-pressure gaseous refrigerant from the compressor 21 to heat the indoor air. The refrigerant flowing from the second portion 32 into the first portion 31 can increase the temperature of the refrigerant flowing from the indoor heat exchanger 101 into the first portion 31, thereby reducing the frosting speed of the first portion 31 and avoiding energy waste.

[0156] To sum up, the air-conditioning system 100 provided in some embodiments of the present disclosure can defrost the first part 31 and the second part 32 in rotation, and can also use hot gas bypass sensible heat defrosting for the first part 31 and medium-pressure latent heat defrosting for the second part 32. While ensuring that the air-conditioning system 100 continuously heats the indoor space and defrosts quickly, it not only utilizes the advantages of simple structure, good effect and low cost of hot gas bypass defrosting, but also avoids serious capacity waste caused by the entire outdoor heat exchanger assembly 3 being defrosted through hot gas bypass.

[0157] Hot gas bypass sensible heat defrosting is as follows: the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 21 enters the outdoor heat exchanger assembly through the bypass flow path, thereby utilizing the sensible heat of the refrigerant to defrost the outdoor heat exchanger assembly.

[0158] Medium-pressure latent heat defrosting is as follows: the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 21 is cooled into a high-pressure and medium-temperature liquid refrigerant after heat exchange, and then enters the outdoor heat exchanger component, thereby utilizing the latent heat of the refrigerant to defrost the outdoor heat exchanger component.

[0159] For example, referring to Figures 22 and 23 , the bypass flow path can be the fifth branch 45 of the second defrost flow path. A portion of the high-temperature, high-pressure gaseous refrigerant from the compressor 21 enters the second portion 32 through the fifth branch 45, thereby utilizing the sensible heat of the refrigerant to perform hot gas bypass sensible heat defrosting on the second portion 32. After heat exchange in the second portion 32, the refrigerant is cooled to a high-pressure, medium-temperature liquid refrigerant, which then enters the first portion 31 through the first branch 41, thereby utilizing the latent heat of the refrigerant to perform medium-pressure latent heat defrosting on the first portion 31.

[0160] In some embodiments, as shown in Figures 3 to 7, the air conditioning system 100 further includes a gas-liquid separator 8, which has a liquid inlet 81 and a gas outlet 82. The liquid inlet 81 is connected to the fourth valve port 64, and the gas outlet 82 is connected to the air intake 211.

[0161] For example, the gas-liquid separator 8 can separate the gas and liquid of the refrigerant entering the compressor 21 to avoid liquid hammer problems in the compressor 21, thereby helping to improve the reliability and stability of the operation of the compressor 21.

[0162] Referring to Figures 4 to 7 , in some embodiments, the outdoor unit 20 further includes a subcooler 9, through which the second throttle valve 52 and the third throttle valve 53 are connected to the second end of the indoor heat exchanger 101. This reduces flash gas generated during the throttling process of the air conditioning system 100, thereby improving the cooling capacity of the air conditioning system 100 and enhancing the operational stability of the compressor 21, thereby improving the stability and reliability of the air conditioning system 100.

[0163] Referring to Figures 4 to 7 , in some embodiments, the air conditioning system 100 further includes a first stop valve 103 and a second stop valve 104. The first stop valve 103 is in communication with a first end of the indoor heat exchanger 101, and the second stop valve 104 is in communication with a second end of the indoor heat exchanger 101. It will be appreciated that when the indoor heat exchanger 101 malfunctions and requires repair or replacement, the first stop valve 103 and the second stop valve 104 can be closed to seal the refrigerant in the indoor heat exchanger 101 within the indoor heat exchanger 101, thereby facilitating repair of the indoor heat exchanger 101.

[0164] For example, the air conditioning system 100 can be a multi-split system. As shown in FIG1 , the air conditioning system 100 includes multiple indoor units 10. Each indoor unit 10 is provided with an indoor heat exchanger 101. The multiple indoor units 10 are arranged in parallel. The first ends of the indoor heat exchangers 101 of the multiple indoor units 10 are connected to a first shutoff valve 103. The second ends of the indoor heat exchangers 101 of the multiple indoor units 10 are connected to a second shutoff valve 104.

[0165] In some embodiments, referring to Figures 4 and 5 , the outdoor fan 22 can be positioned on a side of the first portion 31 away from the second portion 32. This allows the outdoor fan 22 to operate during defrosting of the second portion 32, thereby increasing the heating capacity of the air conditioning system 100 and improving the heating performance of the air conditioning system 100. Alternatively, referring to Figures 6 and 7 , the outdoor fan 22 can be positioned on a side of the second portion 32 away from the first portion 31. This allows the outdoor fan 22 to operate during defrosting of the first portion 31, thereby increasing the heating capacity of the air conditioning system 100 and improving the heating performance of the air conditioning system 100.

[0166] In some embodiments, as shown in Figures 3 to 7 and 11 , the air conditioning system 100 includes a detection assembly configured to detect multiple parameter information of the air conditioning system 100. The controller 40 is electrically connected to the detection assembly. The detection assembly includes a first pressure sensor 71 for detecting suction pressure Ps, a second pressure sensor 72 for detecting discharge pressure Pd, a sixth temperature sensor 73 for detecting discharge temperature Td, a first temperature sensor 74 for detecting pressure reducer temperature Te1 of the first portion 31, a second temperature sensor 75 for detecting pressure reducer temperature Te2 of the second portion 32, a fourth temperature sensor 76 for detecting air pipe temperature Tg1 of the first portion 31, a fifth temperature sensor 77 for detecting air pipe temperature Tg2 of the second portion 32, and a third temperature sensor 78 for detecting outdoor ambient temperature Ta.

[0167] It can be understood that the suction pressure Ps is the suction pressure of the suction port of the compressor, the exhaust pressure Pd is the exhaust pressure of the exhaust port of the compressor, the exhaust temperature Td is the temperature of the exhaust port of the compressor, the air pipe temperature of the first part 31 is the temperature of the first end of the first part 31, the pressure reducer temperature of the first part 31 is the temperature of the second end of the first part 31, the air pipe temperature of the second part 32 is the temperature of the first end of the second part, and the pressure reducer temperature of the second part 32 is the temperature of the second end of the second part 32.

[0168] In some embodiments, the controller 40 is configured as follows: if the air-conditioning system reaches the start condition of the defrost-free mode, the first branch is controlled to be conductive so that the refrigerant of the compressor of the outdoor unit heats the second part, and the second part heats the first part; if the air-conditioning system meets the end condition of the defrost-free mode, the air-conditioning system runs the working mode set by the user.

[0169] Some embodiments of the present disclosure further provide a defrost control method, as shown in FIG. 24 , which includes steps S100 to S400 .

[0170] In step S100 , it is detected whether the air conditioning system meets the defrost-free mode start condition.

[0171] In step S200, if the air conditioning system meets the defrost-free mode start condition, the air conditioning system is controlled to run the defrost-free mode to heat the second part in the outdoor unit, and the second part heats the first part.

[0172] In step S300 , it is detected whether the air conditioning system meets the defrost-free mode termination condition.

[0173] S400: If the air-conditioning system meets the defrost-free mode termination condition, control the air-conditioning system to operate in a preset working mode.

[0174] For example, the preset working mode is a cooling mode, heating mode, or other working mode set by the user.

[0175] It is understood that, upon detecting that the air conditioning system 100 meets the conditions for starting the defrost-free mode, the air conditioning system 100 operates in the defrost-free mode to heat the second portion 32 of the outdoor unit 20, and to cause the second portion 32 to heat the first portion 31. This increases the temperatures of the first portion 31 and the second portion 32, thereby preventing frost from forming on the outdoor heat exchanger assembly 3. Furthermore, during the above process, the air conditioning system 100 can continue to heat the indoor space, effectively preventing frost from forming on the outdoor heat exchanger assembly 3 while maintaining uninterrupted indoor heating. This helps improve the reliability of the compressor and system, and enhances the user experience.

[0176] It should be noted that the defrost control method provided in some embodiments of the present disclosure can be adjusted according to the structure of the air-conditioning system 100.

[0177] In some embodiments, the controller 40 is further configured to: if the air conditioning system meets the defrost-free mode start condition, adjust the first suction superheat Tssh1 of the compressor to be greater than or equal to the first threshold d, and adjust the discharge superheat Tdsh of the compressor to be greater than or equal to the second threshold e.

[0178] For example, 0°C ≤ d < e, Tssh1 = Tg1 - Tcps, Tdsh = Td - Tcpd, Tg1 is the temperature of the first end of the first part, Td is the exhaust temperature of the exhaust port of the compressor, Tcps is the saturation temperature corresponding to the suction pressure of the compressor, and Tcpd is the saturation temperature corresponding to the exhaust pressure of the compressor.

[0179] For example, the value range of d is: 0℃≤d<3℃, 3℃≤d<6℃ or 6℃≤d≤10℃; and / or the value range of e is: 20℃≤e<28℃, 28℃≤e<36℃ or 36℃≤e≤40℃.

[0180] In some embodiments, the defrost-free mode start condition includes: the minimum value Tamin of the outdoor environment temperature is less than or equal to the third threshold a, the minimum value Te1min of the temperature at the second end of the first part or the minimum value Te2min of the temperature at the second end of the second part is less than or equal to the fourth threshold b, and the cumulative operating time of the air-conditioning system in the heating mode reaches a fifth threshold c; for example, -7°C <a<7℃,b≤0℃,10min≤c。

[0181] For example, in the start condition of the no-defrost mode, -7℃ <a<7℃,b=0℃,10min≤c<20min。

[0182] For example, in the start condition of the no-defrost mode, -7℃ <a<7℃,-5℃≤b<0℃,20min≤c<30min。

[0183] For example, in the start condition of the no-defrost mode, -7℃ <a<7℃,b<-5℃,c≥30min。

[0184] In some embodiments, the controller 40 is further configured to: if the air-conditioning system meets the defrost-free mode termination condition, control the fourth branch to be turned on so that the refrigerant in the compressor enters the first part from the exhaust port through the fourth branch and heats the first part.

[0185] In some embodiments, the controller 40 is further configured to: if the air-conditioning system meets the conditions for ending the defrost-free mode, the controller 40 controls the fourth branch to be turned on before adjusting the second suction superheat Tssh2 of the compressor so that Tssh2 ≥ d; and adjusting the exhaust superheat Tdsh of the compressor so that Tdsh ≥ e; for example, Tssh2 = Tg2 - Tcps, where Tg2 is the temperature of the first end of the second part.

[0186] In some embodiments, the controller 40 is further configured to: if the air-conditioning system meets the defrosting mode start condition, compare the minimum value Pdmin of the discharge pressure of the compressor with the first threshold pressure h and the second threshold pressure I respectively, and obtain the comparison result; if Pdmin≥h, control the air volume gear of the indoor fan to be the first air volume gear. For example, the first air volume gear is the air volume gear set by the user; if Pdmin<I, control the indoor fan to stop running; and if I≤Pdmin<h, control the air volume gear of the indoor fan to be the second preset air volume gear; for example, I<h, and the rotational speed of the indoor fan at the second preset air volume gear is less than the maximum rotational speed of the indoor fan.

[0187] For example, 1.5 MPa≤h≤2 MPa, 1 MPa≤I≤1.5 MPa, and the rotational speed of the indoor fan at the second preset air volume gear is less than one-half of the maximum rotational speed of the indoor fan. For example, when h is 1.5 MPa, I is 1 MPa. For example, when h is 1.8 MPa, I is 1 MPa. For example, when h is 1.8 MPa, I is 1.2 MPa. For example, when h is 1.8 MPa, I is 1.5 MPa. For example, when h is 2 MPa, I is 1.2 MPa. For example, when h is 2 MPa, I is 1.5 MPa.

[0188] In some embodiments, the controller 40 is further configured to: if the air-conditioning system meets the defrosting mode start condition, compare the minimum value Tomin of the air outlet temperature of the indoor unit with the first threshold temperature M1 and the second threshold temperature N1 respectively, and obtain the comparison result; compare the minimum value Tlmin of the liquid pipe temperature of the indoor heat exchanger with the third threshold temperature M2 and the fourth threshold temperature N2 respectively, and obtain the comparison result; if Tomin≥M1 or Tlmin≥M2, control the air volume gear of the indoor fan to be the air volume gear set by the user; if Tomin<N1 and Tlmin<N2, control the indoor fan to stop running; and if N1≤Tomin<M1 or N2≤Tlmin<M2, control the air volume gear of the indoor fan to be the second preset air volume gear; for example, N1<M1, N2<M2, and the rotational speed of the indoor fan at the second preset air volume gear is less than the maximum rotational speed of the indoor fan.

[0189] For example, 5°C≤M1≤35°C, 15°C≤N1≤25°C, 20°C≤M2≤40°C, 10°C≤N2≤25°C; the rotational speed of the indoor fan at the second preset air volume gear is less than one-half of the maximum rotational speed of the indoor fan.

[0190] The above defrosting control method will be further described below with reference to FIG. 3 and FIG. 25. In some embodiments, the defrosting control method further includes steps S1 to S5.

[0191] In step S1, when the air conditioning system is operating, multiple temperature values and multiple pressure values during the operation of the air conditioning system are collected.

[0192] For example, in step S2, the multiple temperature values collected include: Ta, Te1, Te2, Tg1, and Tg2, and the multiple pressure values collected include: Ps, Pd, Td.

[0193] It should be noted that when the air conditioning system 100 includes multiple outdoor units 20, there can be multiple of the above-detected parameters. In actual use, when taking values of the above-detected parameters, the maximum or minimum value of the above parameters is taken.

[0194] For example, as shown in FIGS. 3 and 11, when the air conditioning system 100 includes two outdoor units 20, each of the two outdoor units 20 can measure a Tg1. When taking a value of Tg1, the maximum value Tg1max or the minimum value Tg1min thereof can be taken.

[0195] In step S2, it is determined whether the air conditioning system needs to heat.

[0196] If the determination result is yes, it turns to step S3. If the determination result is no, it turns to step S4. [[ID=十六]]

[0197] In step S3, the air conditioning system is controlled to operate in the heating mode. C

[0198] In step S4, the air conditioning system is controlled to operate in the cooling mode.

[0199] After step S3, it turns to step S5.

[0200] In step S5, it is determined whether the air conditioning system meets the start condition of the defrosting-free mode.

[0201] In some embodiments, detecting whether the air conditioning system 100 meets the start condition of the defrosting-free mode includes: detecting the minimum value Tamin of the temperature of the outdoor environment, detecting the minimum value Te1min of the temperature of the pressure reducer of the first part 31, and detecting the minimum value Te2min of the temperature of the pressure reducer of the second part 32. The start condition of the defrosting-free mode includes: Tamin ≤ a, Te1min ≤ b1 or Te2min ≤ b1, and the cumulative operation time of the air conditioning system 100 operating in the heating mode reaches c1 minutes. For example, -7°C < a < 7°C, b1 is 0°C, and 10 min ≤ c1 < 20 min.

[0202] For example, the value of a can be -6°C, -3°C, -1°C, 0°C, 1°C, 3°C, or 6°C, etc.

[0203] For example, the value of c1 can be 10 min, 12 min, 13 min, 14 min, 16 min, or 19 min, etc.

[0204] Through the above configuration, the air conditioning system 100 can determine whether the conditions for starting the defrost-free mode are met based on the above parameters. This facilitates the air conditioning system 100 to promptly adjust to the defrost-free mode, preventing frost from forming on the outdoor heat exchanger assembly 3, thereby preventing the air conditioning system 100 from affecting indoor heating. This helps improve the reliability of the compressor and system, and enhances the user experience. Furthermore, by setting the target values ​​b1 for Te1min and Te2min relatively high, and the target value c1 for the cumulative heating time relatively low, the air conditioning system 100 can more easily enter the defrost-free mode, thereby further preventing the outdoor heat exchanger assembly 3 from maintaining frost.

[0205] In some embodiments, the defrost-free mode starts when: Tamin≤a, Te1min≤b2 or Te2min≤b2, and the air conditioning system operates in heating mode for a cumulative time of c2 minutes. For example, -5°C≤b2<0°C, 20min≤c2<30min.

[0206] For example, the value of b2 may be -4°C, -3°C, -2°C, -1°C, or -0.5°C.

[0207] For example, the value of c2 can be 20 min, 22 min, 23 min, 24 min, 27 min or 29 min, etc.

[0208] Through the above-described configuration, the air conditioning system 100 can determine whether the conditions for starting the defrost-free mode are met based on the above-described parameters. This facilitates the air conditioning system 100 to promptly adjust to the defrost-free mode, preventing frost from forming on the outdoor heat exchanger assembly 3, thereby preventing the air conditioning system 100 from affecting indoor heating. This helps improve the reliability of the compressor and system, and enhances the user experience. Furthermore, by setting the Te1min and Te2min target values ​​b2 relatively high, and the cumulative heating time target value c1 relatively high, the air conditioning system 100 can avoid frequently entering the defrost-free mode, extend the period of continuous indoor heating by the air conditioning system 100, and improve the heating capacity of the air conditioning system 100 to a certain extent.

[0209] In some embodiments, in step S5, if it is determined that the air conditioning system does not meet the defrost-free mode start condition, the process returns to step S3. If it is determined that the air conditioning system 100 meets the defrost-free mode start condition, the process proceeds to step S6.

[0210] S6. Control the air conditioning system to operate in the defrost-free mode.

[0211] In some embodiments, controlling the air conditioning system 100 to operate in the defrost-free mode includes: in the outdoor unit 20, controlling the first valve port 61 to communicate with the second valve port 62, and the third valve port 63 to communicate with the fourth valve port 64; adjusting the second throttle valve 52 to a fully closed state, adjusting the third throttle valve 53 to a fully open state, controlling the second on-off valve 54 to switch to a closed state, adjusting the first throttle valve 51 to a throttle state, and controlling the outdoor fan 22 to operate; adjusting the first suction superheat Tssh1 of the compressor 21 so that Tssh1 ≥ d; and adjusting the discharge superheat Tdsh of the compressor 21 so that Tdsh ≥ e. For example, 0℃≤d≤10℃, 20℃≤e≤40℃, Tssh1=Tg1-Tcps, Tdsh=Td-Tcpd, Tg1 is the gas pipe temperature of the first part 31, Td is the exhaust temperature of the exhaust port 212 of the compressor 21, Tcps is the saturation temperature corresponding to the suction pressure Ps of the compressor 21, and Tcpd is the saturation temperature corresponding to the exhaust pressure Pd of the compressor 21.

[0212] It should be noted that, as indicated above in the outdoor unit 20, when the air-conditioning system 100 includes multiple outdoor units 20, the outdoor heat exchanger assembly 3 in one of the outdoor units 20 can be heated first to prevent the outdoor heat exchanger assembly 3 in the outdoor unit 20 from frosting; or the outdoor heat exchanger assemblies 3 in multiple outdoor units 20 can be heated at the same time to prevent the outdoor heat exchanger assemblies 3 in the multiple outdoor units 20 from frosting. The above-mentioned heating of the outdoor heat exchanger assembly 3 in the outdoor unit 20 can be selected according to actual conditions.

[0213] Taking the air-conditioning system 100 including the outdoor unit 20A and the outdoor unit 20B as an example, when determining whether the air-conditioning system 100 meets the start conditions of the defrost-free mode in step S5, the relevant parameters in the outdoor unit 20A meet the start conditions of the defrost-free mode, while the relevant parameters in the outdoor unit 20B do not meet the start conditions of the defrost-free mode. In this case, controlling the air-conditioning system 100 to operate in the defrost-free mode can enable the refrigerant in the outdoor unit 20A to heat the outdoor heat exchanger assembly 3, while the refrigerant in the outdoor unit 20B still flows according to the refrigerant flow direction in the original heating mode. In this way, the outdoor heat exchanger assembly 3 can be heated more specifically to avoid heat waste in the refrigerant.

[0214] Alternatively, when determining in step S5 whether the air-conditioning system 100 meets the start conditions of the defrost-free mode, the relevant parameters in the outdoor unit 20A meet the start conditions of the defrost-free mode, and the relevant parameters in the outdoor unit 20B also meet the start conditions of the defrost-free mode. In this case, controlling the air-conditioning system 100 to operate the defrost-free mode can enable the refrigerant in the outdoor unit 20A and the refrigerant in the outdoor unit 20B to heat the outdoor heat exchanger assembly 3 at the same time.

[0215] For example, the value of d may be 0°C, 2°C, 4°C, 6°C, 8°C, or 10°C.

[0216] For example, the value of e may be 20°C, 25°C, 30°C, 34°C, 38°C, or 40°C.

[0217] Through the above arrangement, the high-temperature, high-pressure gaseous refrigerant discharged from the exhaust port 212 of the compressor 21 flows into the reversing assembly 6 through the first valve port 61 and out of the reversing assembly 6 through the second valve port 62. The refrigerant flowing out of the second valve port 62 flows to the indoor heat exchanger 101, where it undergoes heat exchange and is cooled to a high-pressure, medium-temperature liquid refrigerant to heat the indoor space. The refrigerant then flows out of the indoor heat exchanger 101 and flows to the third throttle valve 53. After passing through the third throttle valve 53, it flows into the second portion 32, where the waste heat of the refrigerant heats the second portion 32. The refrigerant is then throttled by the first throttle valve 51 and flows to the first portion 31, where it evaporates into a low-temperature, low-pressure gaseous refrigerant. Finally, the refrigerant flowing out of the first portion 31 flows back to the intake port 211 of the compressor 21 through the third valve port 63 and the fourth valve port 64.

[0218] Furthermore, during the above process, the heated second portion 32 can heat the surrounding air, raising the temperature of the surrounding air. After the outdoor fan 22 is operating, the hot air surrounding the second portion 32 can be blown toward the first portion 31, thereby heating the first portion 31 to prevent frost on the first portion 31. Simultaneously, the heated second portion 32 can also heat the first portion 31 through heat conduction and heat radiation between the pipes to prevent frost on the first portion 31. Therefore, the air conditioning system 100 provided in some embodiments of the present disclosure can prevent frost on the outdoor heat exchanger assembly 3, improve the heating capacity of the air conditioning system 100, and improve the reliability of the compressor and system to a certain extent. At the same time, during the above process, the indoor unit 10 can continuously heat the room, improving the thermal comfort of indoor users and enhancing the user experience.

[0219] In step S6, the air-conditioning system can continue to heat the first part 31 and the second part 32, thereby increasing the temperature of the outdoor heat exchanger assembly 3, and making the temperature of the outdoor heat exchanger assembly 3 higher than the temperature at which frost is formed, thereby avoiding frost on the first part 31 and the second part 32 of the outdoor heat exchanger assembly 3.

[0220] In step S7, it is determined whether the air conditioning system meets the defrost-free mode termination condition.

[0221] For example, the defrost-free mode termination condition includes: the minimum value Tg1min in Tg1≥f and the duration is g seconds. For example, 0°C≤f≤10°C, 5 seconds≤g≤30 seconds.

[0222] For example, the value of f may be 0°C, 2°C, 4°C, 6°C, 8°C, or 10°C.

[0223] For example, the value of g can be 5 seconds, 10 seconds, 15 seconds, 20 seconds, 25 seconds or 30 seconds, etc.

[0224] Through the above arrangement, the temperature of the outdoor heat exchanger assembly 3 is relatively high and a certain amount of heat is retained. At this time, even if the outdoor heat exchanger assembly 3 is no longer heated, it is difficult for the outdoor heat exchanger assembly 3 to frost.

[0225] In step S8, the air conditioning system is controlled to operate in a preset working mode.

[0226] At this point, the control of the air conditioning system 100 provided in the above embodiment is completed.

[0227] However, in some cases, the first portion 31 of the air-conditioning system 100 may be heavily frosted. After the air-conditioning system 100 operates in the defrost-free mode, some frost may still remain on the first portion 31 .

[0228] Therefore, in some embodiments, as shown in FIG26 , after the above-mentioned detection that the air-conditioning system 100 reaches the end condition of the defrost-free mode, before the air-conditioning system 100 is operated in the working mode set by the user, the above-mentioned defrost control method further includes steps S110 to S130.

[0229] In step S110 , the air conditioning system 100 is controlled to operate in a defrost mode to heat the first part 31 in the outdoor unit 20 .

[0230] In step S120 , it is detected whether the defrosting of the first part 31 is completed.

[0231] In step S130 , if completed, the air conditioning system 100 is controlled to exit the defrost mode.

[0232] Through the above arrangement, the air conditioning system 100 can heat the first portion 31 alone, so that the first portion continues to heat up, which is beneficial for removing frost on the first portion 31.

[0233] In some embodiments, as shown in FIG. 11 and FIG. 27 , the defrost control method of the air-conditioning system 100 includes steps S1A to S11A.

[0234] In step S1A, a plurality of temperature values ​​and a plurality of pressure values ​​are collected during the operation of the air-conditioning system.

[0235] For example, in step S210 , the multiple temperature values ​​collected include Ta, Te1, Te2, Tg1, and Tg2, and the multiple pressure values ​​collected include Ps, Pd, and Td.

[0236] It should be noted that, when the air-conditioning system 100 includes multiple outdoor units 20, there may be multiple parameters detected. In actual use, the maximum or minimum value of the detected parameters is taken.

[0237] For example, as shown in FIG3 and FIG11, when the air conditioning system 100 includes two outdoor units 20, each of the two outdoor units 20 can measure a Tg1. When taking the value of Tg1, the maximum value Tg1max or the minimum value Tg1min can be taken.

[0238] In step S2A, it is determined whether the air conditioning system needs to heat.

[0239] If the judgment result is yes, the process goes to S3A. If the judgment result is no, the process goes to S4A.

[0240] In step S3A, the air conditioning system is controlled to operate in a heating mode.

[0241] In step S4A, the air conditioning system is controlled to operate in cooling mode.

[0242] After step S3A, the process goes to step S5A.

[0243] In step S5A, it is determined whether the air conditioning system satisfies the defrost-free mode start condition.

[0244] In some embodiments, the condition for starting the air conditioning system 100 in the defrost-free mode is as follows: Tamin≤a, Te1min≤b3 or Te2min≤b3, and the cumulative running time of the air conditioning system 100 in the heating mode reaches c3 minutes. <a<7℃,b3<-5℃,c3≥30min。

[0245] For example, the value of a may be -6°C, -3°C, -1°C, 0°C, 1°C, 3°C, or 6°C.

[0246] For example, the value of b3 may be -6°C, -7°C, -8°C, -9°C, -10°C, -13°C, or -16°C.

[0247] For example, the value of c3 can be 30 min, 32 min, 33 min, 34 min, 36 min or 39 min, etc.

[0248] Through the above-described configuration, the air conditioning system 100 can determine whether the conditions for starting the defrost-free mode are met based on the above-described parameters. This facilitates the air conditioning system 100 to promptly adjust to the defrost-free mode, preventing frost from forming on the outdoor heat exchanger assembly 3, thereby preventing the air conditioning system 100 from affecting indoor heating. This helps improve the reliability of the compressor and system, and enhances the user experience. Furthermore, by setting the target values ​​b1 for Te1min and Te2min relatively low, and the target value c3 for the cumulative heating time relatively high, the air conditioning system 100 can further prevent the air conditioning system 100 from frequently entering the defrost-free mode, further extend the period of continuous indoor heating by the air conditioning system 100, and improve the heating capacity of the air conditioning system 100 to a certain extent.

[0249] If it is determined in step S5A that the air conditioning system 100 does not meet the defrost-free mode start condition, the process returns to step S3A. If it is determined that the air conditioning system 100 does not meet the defrost-free mode start condition, the process returns to step S6A.

[0250] In step S6A, the air conditioning system is controlled to operate in a defrost-free mode.

[0251] The method of controlling the air conditioning system 100 to operate in the defrost-free mode is the same as that of the previous embodiment and will not be repeated here.

[0252] In step S6A, the air-conditioning system can continue to heat the first part 31 and the second part 32, thereby increasing the temperature of the outdoor heat exchanger assembly 3 and making the temperature of the outdoor heat exchanger assembly 3 higher than the temperature at which frost is formed, thereby avoiding frost on the first part 31 and the second part 32 of the outdoor heat exchanger assembly 3.

[0253] In step S7A, it is determined whether the air conditioning system meets the defrost-free mode termination condition. If the air conditioning system does not meet the defrost-free mode termination condition, the process returns to step S6A; if the air conditioning system meets the defrost mode termination condition, the process returns to step S8A.

[0254] For example, the defrost-free mode termination condition includes: the minimum value Tg2min in Tg2≥f and the duration is g seconds. For example, 0°C≤f≤10°C.

[0255] For example, the value of f may be 0°C, 2°C, 4°C, 6°C, 8°C, or 10°C.

[0256] For example, the value of g can be 5 seconds, 10 seconds, 15 seconds, 20 seconds, 25 seconds or 30 seconds, etc.

[0257] Through the above arrangement, the temperature of the second portion 32 can be kept relatively high, and a certain amount of heat can be retained. At this time, even if the second portion 32 is no longer heated, it is difficult for the second portion 32 to frost.

[0258] In step S8A, the air conditioning system 100 is controlled to operate in a defrost mode.

[0259] In some embodiments, in step S8A, controlling the air conditioning system 100 to operate in the defrost mode includes: in the outdoor unit 20, controlling the first valve port 61 to communicate with the second valve port 62, and the third valve port 63 to communicate with the fourth valve port 64. Adjusting the first throttle valve 51 to a fully closed state, adjusting the second throttle valve 52 to a fully closed state, and adjusting the third throttle valve 53 to a throttled state to control the suction / discharge superheat of the compressor 21; controlling the second on-off valve 54 to open; controlling the first on-off valve 55 to open; and controlling the operation of the outdoor fan 22. Adjusting the second suction superheat Tssh2 of the compressor 21 to ensure that Tssh2 ≥ d; and adjusting the discharge superheat Tdsh of the compressor 21 to ensure that Tdsh ≥ e. For example, Tssh2 = Tg2 - Tcps, where Tg2 is the gas pipe temperature of the second portion 32.

[0260] Through the above arrangement, a portion of the high-temperature, high-pressure gaseous refrigerant discharged from the exhaust port 212 of the compressor 21 can flow into the reversing assembly 6 through the first valve port 61 and out of the reversing assembly 6 through the second valve port 62. The refrigerant flowing out of the second valve port 62 flows to the indoor heat exchanger 101, where it undergoes heat exchange and is cooled into a high-pressure, medium-temperature liquid refrigerant to heat the room. Then, the high-pressure, medium-temperature liquid refrigerant flows from the indoor heat exchanger 101 to the third throttle valve 53, where it is throttled and flows into the second portion 32, where it is evaporated into a low-temperature, low-pressure gaseous refrigerant. Finally, the low-temperature, low-pressure gaseous refrigerant flows out of the second portion 32 and flows back to the intake port 211 of the compressor 21 through the second on-off valve 54, the third valve port 63, and the fourth valve port 64 in sequence. Another part of the high-temperature and high-pressure gaseous refrigerant discharged from the exhaust port 212 of the compressor 21 flows into the first part 31 through the fourth branch 44 and the first on-off valve 55. The refrigerant flowing out of the first part 31 flows back to the intake port 211 of the compressor 21 through the second on-off valve 54, the third valve port 63 and the fourth valve port 64 in turn.

[0261] Therefore, the sensible high temperature of the refrigerant discharged from the compressor 21 can be used to directly heat the first part 31. In this way, the heating speed of the first part 31 can be accelerated, and the temperature rising speed of the first part 31 can be increased. When the frost on the first part 31 is thick, the defrosting speed of the first part 31 can be increased.

[0262] In step S8 , the air conditioning system continues to heat the first portion 31 .

[0263] In step S9, it is determined whether the air conditioning system meets the defrost mode end condition. If the air conditioning system does not meet the defrost mode end condition, the process returns to step S8; if the air conditioning system meets the defrost mode end condition, the process goes to step S10.

[0264] For example, the above defrosting mode end condition includes: the minimum value Tg1min in Tg1 ≥ f and the duration is g seconds. For example, 0°C ≤ f ≤ 10°C, 5 seconds ≤ g ≤ 30 seconds.

[0265] For example, the value of f can be 0°C, 2°C, 4°C, 6°C, 8°C, 10°C, etc.

[0266] For example, the value of g can be 5 seconds, 10 seconds, 15 seconds, 20 seconds, 25 seconds, 30 seconds, etc.

[0267] Through the above settings, the temperature of the first part 31 is relatively high and a certain amount of heat is stored. At this time, even if the first part 31 is no longer heated continuously, it is difficult for the first part 31 to frost.

[0268] In step S10, control the air conditioning system to operate in a preset working mode.

[0269] In some embodiments, as shown in FIG. 28, the method for controlling the air conditioning system 100 to operate in a defrost-free mode further includes steps S210A to S230A.

[0270] S210A. Detect the minimum value Pdmin of the exhaust pressure Pd at the exhaust port 212 of the compressor 21.

[0271] S220A. Compare the minimum value Pdmin of the exhaust pressure with the first threshold pressure h and the second threshold pressure I respectively, and obtain the comparison result.

[0272] S230A. If Pdmin ≥ h, control the air volume gear of the indoor fan 102 to be the first preset air volume gear; if Pdmin < I, control the indoor fan 102 to stop running; if I ≤ Pdmin < h, control the air volume gear of the indoor fan 102 to be the second preset air volume gear;

[0273] For example, 1.5 MPa ≤ h ≤ 2 MPa, 1 MPa ≤ I ≤ 1.5 MPa, and I < h. The rotational speed of the indoor fan 102 at the above second preset air volume gear is less than half of the highest rotational speed of the indoor fan 102.

[0274] For example, the value of h can be 1.5 MPa, 1.6 MPa, 1.8 MPa, 1.9 MPa, 2 MPa, etc.

[0275] For example, the value of I can be 1 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.5 MPa, etc.

[0276] For example, the air volume gears of the indoor fan 102 include low gear, medium gear, and high gear.

[0277] The rotation speed of the indoor fan 102 at high gear is the highest rotation speed of the indoor fan 102.

[0278] For example, if the rotation speed of the indoor fan 102 at high gear is 3000 r / min, then the rotation speed of the indoor fan 102 at the second preset air volume gear needs to be less than 1500 r / min.

[0279] Through the above settings, the frosting risk of the outdoor heat exchanger assembly 3 can be judged according to the exhaust pressure Pd of the exhaust port 212 of the compressor 21, and the air volume gear of the indoor fan 102 can be flexibly adjusted according to the frosting risk of the outdoor heat exchanger assembly 3, so that the air volume gear of the indoor fan 102 can be matched with the heating performance of the air-conditioning system. In this way, on the basis of avoiding frosting of the outdoor heat exchanger assembly 3, the heating capacity of the air-conditioning system can be maximally utilized for indoor heating.

[0280] In some embodiments, as shown in FIG. 29, steps S210A to step S230A include steps S71A to step S76A.

[0281] In step S71A, the minimum value Pdmin of the exhaust pressure of the exhaust port of the compressor is detected.

[0282] In step S72A, it is judged whether Pdmin≥h holds.

[0283] If so, it turns to step S73; if not, that is, at this time I≤Pdmin<h, it turns to step S74.

[0284] In step S73A, the air volume gear of the indoor fan 102 is controlled to be the first preset air volume gear.

[0285] In this case, the exhaust pressure Pd of the exhaust port 212 of the compressor 21 is relatively large, and the heating performance of the air-conditioning system 100 is good, which can reduce the frosting risk of the outdoor heat exchanger assembly 3. At this time, even if the user adjusts the air volume gear of the indoor fan 102 to high gear, so that most of the heat in the refrigerant is configured to heat the room, there will still be enough heat in the refrigerant to enter the outdoor heat exchanger assembly 3 to increase the temperature of the outdoor heat exchanger assembly 3, and frosting of the outdoor heat exchanger assembly 3 can be avoided.

[0286] In step S74A, it is judged whether Pdmin≥I holds.

[0287] In this case, the exhaust pressure Pd of the exhaust port 212 of the compressor 21 is relatively small, and it is necessary to further detect the exhaust pressure Pd of the exhaust port 212 of the compressor 21 to adjust the rotation speed of the indoor fan 102 according to the final detection result.

[0288] If so, it turns to step S75A; if not, it turns to step S76A.

[0289] In step S75A, the air volume of the indoor fan 102 is adjusted to the second preset air volume.

[0290] In this case, the air volume of the indoor fan 102 is controlled to be the second preset air volume, so that a small part of the heat in the refrigerant is configured to raise the indoor temperature, so that the refrigerant will have enough heat to enter the outdoor heat exchanger assembly 3, which is configured to increase the temperature of the outdoor heat exchanger assembly 3, thereby avoiding frosting on the outdoor heat exchanger assembly 3.

[0291] In step S76A, the indoor fan 102 is controlled to stop running.

[0292] In this case, the exhaust pressure Pd at the exhaust port 212 of the compressor 21 is small, the heating performance of the air-conditioning system 100 is poor, and the risk of frosting on the outdoor heat exchanger assembly 3 is high. At this time, controlling the indoor fan 102 to stop running can make a very small part of the heat in the refrigerant be configured to raise the indoor temperature, so that most of the heat in the refrigerant enters the outdoor heat exchanger assembly 3 and is configured to increase the temperature of the outdoor heat exchanger assembly 3, thereby avoiding frosting on the outdoor heat exchanger assembly 3.

[0293] In some embodiments, as shown in FIG. 30, the method for controlling the air-conditioning system 100 to operate in the defrost-free mode further includes steps S_{210B} to S_{230B}.

[0294] In step S_{210B}, the minimum value T_{omin} of the air outlet temperature of the indoor unit 10 is detected, and the minimum value T_{lmin} of the liquid pipe temperature of the indoor heat exchanger 101 is detected.

[0295] In step S_{220B}, the minimum value T_{omin} of the air outlet temperature of the indoor unit 10 is respectively compared with the first threshold temperature M1 and the second threshold temperature N1, and the comparison results are obtained; the minimum value T_{lmin} of the liquid pipe temperature of the indoor heat exchanger 101 is respectively compared with the third threshold temperature M2 and the fourth threshold temperature N2, and the comparison results are obtained.

[0296] In step S_{230B}, if T_{omin}≥M1 or T_{lmin}≥M2, the air volume of the indoor fan 102 is controlled to be the first preset air volume; if T_{omin}<N1 or T_{lmin}<N2, the indoor fan 102 is controlled to stop running; if N1≤T_{omin}<M1 and N2≤T_{lmin}<M2, the air volume of the indoor fan 102 is controlled to be the second preset air volume. Both the first preset air volume and the second preset air volume can be air volumes set by the user.

[0297] For example, 25°C≤M1≤35°C, 15°C≤N1≤25°C, and N1<M1, 20°C≤M2≤40°C, 10°C≤N2≤25°C, and N2<M2.

[0298] For example, the value of M1 may be 25°C, 28°C, 30°C, 32°C, 34°C, or 35°C.

[0299] For example, the value of N1 may be 15°C, 17°C, 19°C, 21°C, 23°C, or 25°C.

[0300] For example, the value of M2 may be 20°C, 25°C, 30°C, 34°C, 38°C, or 40°C.

[0301] For example, the value of N2 may be 10°C, 14°C, 18°C, 20°C, 22°C, or 25°C.

[0302] Through the above configuration, the frost risk of the outdoor heat exchanger assembly 3 can be determined based on the air outlet temperature of the indoor unit 10 and the liquid pipe temperature of the indoor heat exchanger 101. The wind speed of the indoor fan 102 can be flexibly adjusted based on the frost risk of the outdoor heat exchanger assembly 3, thereby matching the wind speed of the indoor fan 102 with the heating performance of the air conditioning system 100. In this way, the heating capacity of the air conditioning system 100 can be maximized to heat the indoor space while preventing frost on the outdoor heat exchanger assembly 3.

[0303] In some embodiments, as shown in FIG. 31 , steps S210B to S230B include steps S71B to S76B.

[0304] In step S71B, the minimum value Tomin of the air outlet temperature of the indoor unit 10 is detected, and the minimum value Tlmin of the liquid pipe temperature of the indoor heat exchanger 101 is detected.

[0305] In step S72B, it is determined whether Tmin≥M1 or Tlmin≥M2 holds.

[0306] If so, go to step S73B; if not, go to step S74B.

[0307] In step S73B, the wind speed of the indoor fan 102 is controlled to be the first preset wind speed.

[0308] In this case, the air outlet temperature of the indoor unit 10 is relatively high, the liquid pipe temperature of the indoor heat exchanger 101 is relatively high, and the heating performance of the air-conditioning system 100 is relatively good, which can reduce the risk of frost on the outdoor heat exchanger assembly 3. At this time, even if the user adjusts the wind speed of the indoor fan 102 to high, so that most of the heat in the refrigerant is configured to heat the indoor temperature, the refrigerant will have enough heat to enter the outdoor heat exchanger assembly 3, and is configured to increase the temperature of the outdoor heat exchanger assembly 3, which can avoid frost on the outdoor heat exchanger assembly 3.

[0309] In step S74B, it is determined whether Tmin≥N1 or Tlmin≥N2 holds.

[0310] In this case, the air outlet temperature of the indoor unit 10 is low and the liquid pipe temperature of the indoor heat exchanger 101 is low. It is necessary to further detect the minimum value Tomin of the air outlet temperature of the indoor unit 10 and the minimum value Tlmin of the liquid pipe temperature of the indoor heat exchanger 101 to adjust the speed of the indoor fan 102 according to the final detection results.

[0311] If so, go to step S75B; if not, go to step S76B.

[0312] In step S75B, the wind speed of the indoor fan 102 is controlled to be the second preset wind speed.

[0313] In this case, the wind speed of the indoor fan 102 is controlled to the second preset wind speed, so that a small part of the heat in the refrigerant is configured to heat the indoor temperature, so that the refrigerant has enough heat to enter the outdoor heat exchanger assembly 3, and is configured to increase the temperature of the outdoor heat exchanger assembly 3, thereby avoiding frost on the outdoor heat exchanger assembly 3.

[0314] In step S76B, the indoor fan 102 is controlled to stop operating.

[0315] In this case, the air outlet temperature of the indoor unit 10 is low, the liquid pipe temperature of the indoor heat exchanger 101 is low, the heating performance of the air-conditioning system 100 is poor, and the risk of frost on the outdoor heat exchanger assembly 3 is high. At this time, controlling the indoor fan 102 to stop running can allow a small amount of heat in the refrigerant to be configured to heat the indoor temperature, so that most of the heat in the refrigerant enters the outdoor heat exchanger assembly 3 and is configured to increase the temperature of the outdoor heat exchanger assembly 3 to avoid frost on the outdoor heat exchanger assembly 3.

[0316] In some embodiments, the controller 40 is further configured to: when the air conditioning system 100 operates in the heating mode, if the outdoor ambient temperature detected by the third temperature sensor 78 of any outdoor unit 20 is less than or equal to a first temperature threshold A, if either Te1 of the outdoor unit 20 or Te2 of the outdoor unit 20 is less than or equal to a second temperature threshold B, and if the air conditioning system 100 has been operating in the heating mode for a first set duration, determine that the air conditioning system 100 meets the defrost condition and control the air conditioning system 100 to operate in the first defrost mode or the second defrost mode; for example, when the air conditioning system 100 operates in the first defrost mode, the air conditioning system 100 defrosts at least one first portion 31, and when the air conditioning system 100 operates in the second defrost mode, the air conditioning system 100 defrosts at least one second portion 32. This allows accurate determination of whether the air conditioning system 100 is defrosting, thereby improving the sensitivity and reliability of the defrost control of the air conditioning system 100.

[0317] It will be appreciated that when the air conditioning system 100 includes a single outdoor unit 20, the outdoor ambient temperature detected by the third temperature sensor 78 of the outdoor unit 20 is less than or equal to the first temperature threshold A, and either Te1 or Te2 of the outdoor unit 20 is less than or equal to the second temperature threshold B, the air conditioning system 100 is controlled to operate in the defrost mode. When the air conditioning system 100 includes multiple (greater than or equal to two) outdoor units 20, the outdoor ambient temperature Ta detected by the third temperature sensor 78 of any outdoor unit 20 is less than or equal to the first temperature threshold A, and either Te1 of the multiple outdoor units 20 or Te2 of the multiple outdoor units 20 is less than or equal to the second temperature threshold B, the controller 40 controls the air conditioning system 100 to operate in the defrost mode. In other words, the temperature parameter that triggers the air conditioning system 100 to enter the defrost mode can be a parameter detected by the detection component of the same outdoor unit 20, or can be a parameter detected by the detection components of different outdoor units 20.

[0318] For example, the first temperature threshold A can take a value in the range of -7°C to 7°C. For example, the first temperature threshold A can be -6°C, -5°C, -4°C, -3°C, -2°C, -1°C, 0°C, 1°C, 2°C, 3°C, 4°C, 5°C or 6°C, etc.

[0319] For example, the second temperature threshold B may be in the range of -5°C to 0°C, and the second temperature threshold B may be -5°C, -4°C, -3°C, -2°C, -1°C or 0°C, etc.

[0320] For example, the first set time length is greater than or equal to 10 minutes. For example, the first set time length may be 10 minutes, 11 minutes, 12 minutes, 13 minutes, or 14 minutes.

[0321] For example, if the air-conditioning system 100 includes multiple (greater than or equal to 2) outdoor units 20, when the air-conditioning system 100 operates in the first defrost mode, the air-conditioning system 100 can defrost the first part 31 of one outdoor unit 20, or defrost the first parts 31 of some outdoor units 20 at the same time, or defrost the first parts 31 of multiple outdoor units 20 at the same time.

[0322] For example, if the air-conditioning system 100 includes multiple (greater than or equal to 2) outdoor units 20, when the air-conditioning system 100 operates in the second defrost mode, the air-conditioning system 100 can defrost the second part 32 of one outdoor unit 20, or defrost the second parts 32 of some outdoor units 20 at the same time, or defrost the second parts 32 of multiple outdoor units 20 at the same time.

[0323] In some embodiments, referring to Figures 4 and 6 , the second end of the fifth branch 45 of the outdoor unit 20 is connected to the second end of the second portion 32, and the second end of the first branch 41 is connected to the first end of the second portion 321. A fourth temperature sensor 76 is disposed at the first end of the first portion 31 and is configured to detect a temperature Tg1 at the first end of the first portion 31. The controller 40 is electrically connected to the fourth temperature sensor 76 and is further configured to: when the air conditioning system 100 is operating in the first defrost mode, if Tg1 of at least one first portion 31 is greater than or equal to a third temperature threshold C and persists for a second predetermined period, determine that the air conditioning system 100 has completed defrosting the at least one first portion 31, and control the air conditioning system 100 to exit the first defrost mode. This allows the air conditioning system 100 to exit the first defrost mode promptly when the first defrost mode termination conditions are met, thereby improving the intelligence and reliability of the air conditioning system 100.

[0324] It is understandable that when the first parts 31 of the plurality of outdoor units 20 are defrosted simultaneously, when Tg1 of the plurality of outdoor units 20 is greater than or equal to the third temperature threshold C, the controller 40 controls the air conditioning system 100 to exit the first defrost mode.

[0325] In some embodiments, the second end of the fifth branch 45 of the outdoor unit 20 is connected to the second end of the second portion 32, and the second end of the first branch 41 is connected to the first end of the second portion 321. A fifth temperature sensor 77 is disposed at the first end of the second portion 32 and is configured to detect a temperature Tg2 at the first end of the second portion. The controller 40 is electrically connected to the fifth temperature sensor 77 and is further configured to: when the air conditioning system 100 is operating in the second defrost mode, if Tg2 of at least one second portion 32 is greater than or equal to a third temperature threshold C and persists for a second predetermined period of time, determine that the air conditioning system 100 has completed defrosting the at least one second portion 32, and control the air conditioning system 100 to exit the second defrost mode. This allows the air conditioning system 100 to exit the second defrost mode promptly when the second defrost mode termination conditions are met, thereby improving the intelligence and reliability of the air conditioning system 100.

[0326] It is understandable that when the second parts 32 of the plurality of outdoor units 20 are defrosted simultaneously, when Tg2 of the plurality of outdoor units 20 is greater than or equal to the third temperature threshold C, the air conditioning system 100 exits the second defrost mode.

[0327] For example, the third temperature threshold C can be in the range of 10℃ to 25℃. For example, the third temperature threshold C can be 10℃, 11℃, 12℃, 13℃, 14℃, 15℃, 16℃, 17℃, 18℃, 19℃, 20℃, 21℃, 22℃, 23℃, 24℃ or 25℃, etc.

[0328] For example, the second set time length may be in the range of 5 seconds to 30 seconds. For example, the second set time length may be 5 seconds, 10 seconds, 15 seconds, 20 seconds, 25 seconds or 30 seconds.

[0329] In some embodiments, referring to Figures 4 and 6 , a first pressure sensor 71 is disposed at the intake port 211 of the compressor 21, and the controller 40 is electrically connected to the first pressure sensor 71. The controller 40 is further configured to: when the air conditioning system 100 defrosts the first portion 31 of an outdoor unit 20, obtain the maximum intake pressure Psmax of the intake port 211 of the outdoor unit 20; and when the air conditioning system defrosts the second portion 32 of the outdoor unit 20, adjust the flow rate of the throttle assembly 56 of the outdoor unit 20 so that P2 satisfies a second preset condition. The second preset condition includes: the condensing pressure P2 of the second portion 32 ≥ Psmax, where P2 is the saturation pressure corresponding to K1*Tg2+K2*Te2, and 0.5≤K1≤0.9 and 0.1≤K2≤0.5. This ensures that the condensing temperature within the second portion 32 is greater than 0°C, ensuring a fast and effective defrosting of the second portion 32.

[0330] For example, the values ​​of K1 and K2 may be K1=0.9, K2=0.1; or, the values ​​of K1 and K2 may be K1=0.5, K2=0.5; or, the values ​​of K1 and K2 may be K1=0.7, K2=0.3.

[0331] For example, specific parameter values ​​can be set, such as setting P2 to be greater than 0.7 MPa (corresponding to a saturation temperature of 0°C). For example, P2 can be greater than or equal to 1.0 MPa and less than or equal to 1.2 MPa. This ensures both the defrosting speed and effect of the second portion 32 while also ensuring the heating performance of the air conditioning system and improving user comfort.

[0332] In some embodiments, the controller 40 is further configured to adjust the flow rate of the first throttle valve 51 of the outdoor unit 20 when the air conditioning system 100 defrosts the second portion 32 of the outdoor unit 20 so that ΔT satisfies a first preset condition. The first preset condition includes: ΔT is greater than or equal to 10°C and less than or equal to a fourth temperature threshold D, where ΔT = Te2 - Tg2. This allows the refrigerant to fully exchange heat and condense in the second portion 32, ensuring a defrosting effect on the second portion 32.

[0333] For example, the fourth temperature threshold D may be set within the range of 20°C to 30°C, such as 20°C, 25°C, 30°C, etc. The value of ΔT may be 10°C, 15°C, 20°C, 25°C, 30°C, etc.

[0334] In some embodiments, as shown in FIG3 , a second pressure sensor 72 is disposed at the exhaust port 212 of the compressor 21, and a sixth temperature sensor 73 is disposed at the exhaust port 212 of the compressor 21. The controller 40 is electrically connected to both the second pressure sensor 72 and the sixth temperature sensor 73. The controller 40 is further configured to, when the air conditioning system 100 defrosts the first portion 31 of an outdoor unit 20, adjust the flow rate of the third throttle valve 53 of the outdoor unit 20 so that the suction superheat Tssh and the discharge superheat Tdsh of the compressor 21 meet a third preset condition. The third preset condition includes: the suction superheat Tssh of the compressor 21 of the outdoor unit 20 is greater than or equal to a fifth temperature threshold E, and the discharge superheat Tdsh of the compressor 21 is greater than or equal to a sixth temperature threshold F. It can be understood that Tssh = Tg2 - Tc_ps, where Tc_ps is the saturation temperature corresponding to the suction pressure Ps at the suction port 211, and Tdsh = Td - Tc_pd, where Td is the temperature of the exhaust port 212 of the compressor 21, and Tc_pd is the saturation temperature corresponding to the exhaust pressure Pd at the exhaust port 212. This prevents the compressor 21 from carrying liquid into compression, thereby improving the reliability of the air conditioning system 100.

[0335] In some embodiments, the controller 40 is further configured to: when the air-conditioning system 100 defrosts the second part 32 of an outdoor unit 20, adjust the flow rate of the second throttle valve 52 of an outdoor unit 20 so that the suction superheat Tssh and the exhaust superheat Tdsh of the compressor 21 meet the third preset condition.

[0336] For example, the sixth temperature threshold F can be in the range of 0°C to 10°C, for example, the sixth temperature threshold F can be 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, etc.

[0337] For example, the fifth temperature threshold E may be within the range of 20°C to 40°C, for example, the fifth temperature threshold E may be 20°C, 25°C, 30°C, 35°C or 40°C.

[0338] In some embodiments, as shown in FIG32 , the air conditioning system 100 is a multi-split air conditioning system 100 including N outdoor units 20 connected in parallel between the first and second ends of the indoor heat exchanger 101. For example, N ≥ 2. This improves the performance of the air conditioning system 100 and enhances the user experience.

[0339] In some embodiments, when the air conditioning system 100 includes N outdoor units 20, the controller 40 is further configured to: when controlling the air conditioning system 100 to operate in a first defrost mode, control the air conditioning system 100 to defrost the N first sections 31 of the N outdoor units 20; and when controlling the air conditioning system 100 to operate in a second defrost mode, control the air conditioning system 100 to defrost the N second sections 32 of the N outdoor units 20. This shortens the total time required to complete defrosting of the N outdoor units 20, simplifies control, and enables the use of a single-module control logic for defrosting a single outdoor unit 20. Furthermore, after defrosting is complete, the N outdoor units 20 are in the same state, preventing flow deviation between the outdoor units due to severe frost on some of the outdoor units 20.

[0340] In some embodiments, when the air conditioning system 100 includes N outdoor units 20, the controller 40 is further configured to: obtain a defrost order for the N outdoor units 20; and control the air conditioning system 100 to alternately operate in a first defrost mode and a second defrost mode to sequentially defrost the outdoor heat exchanger assemblies 3 of the N outdoor units 20 according to the defrost order. For example, when the air conditioning system 100 operates in the first defrost mode, the air conditioning system 100 defrosts the first portion 31 of one outdoor unit 20; and when the air conditioning system 100 operates in the second defrost mode, the air conditioning system 100 defrosts the second portion 32 of one outdoor unit 20. That is, after the air conditioning system 100 defrosts the first portion 31 and the second portion 32 of one outdoor unit 20, it defrosts the first portion 31 and the second portion 32 of the next outdoor unit 20 until all the first portions 31 and the second portions 32 of the N outdoor units 20 are defrosted. When defrosting each outdoor unit 20, the first portion 31 or the second portion 32 may be defrosted first. In this way, during defrosting, a greater number of evaporators are used for heating, and the heating performance of the air-conditioning system 100 is stronger.

[0341] In some embodiments, some embodiments of the present disclosure further provide a defrost control method for an air-conditioning system. Please refer to FIG. 33 . The defrost control method includes steps S1B to S6B.

[0342] In step S1B, the air conditioning system is controlled to operate in a heating mode.

[0343] For example, when the air-conditioning system 100 operates in the heating mode, the first valve port 61 of the reversing assembly 6 of each outdoor unit 20 is controlled to be connected to the second valve port 62, the third valve port 63 is controlled to be connected to the fourth valve port 64, the second on-off valve 54 is controlled to switch to the open state, the second throttle valve 52 is adjusted to the throttling state, the third throttle valve 53 is adjusted to the throttling state, the throttling assembly 56 is adjusted to the fully closed state, the first on-off valve 55 is controlled to switch to the closed state, and the first throttle valve 51 is adjusted to the fully closed state.

[0344] In step S2B, it is determined whether the air conditioning system meets the defrosting conditions.

[0345] If the air conditioning system 100 does not meet the defrost conditions, the process returns to step S1B. If the air conditioning system 100 meets the defrost conditions, the process proceeds to step S3B. The defrost conditions include the outdoor ambient temperature, the operating time of the air conditioning system 100, and the temperature of at least one first portion or at least one second portion.

[0346] In step S3B, the air conditioning system is controlled to operate in the first defrost mode.

[0347] In this manner, the air conditioning system 100 can defrost at least one first portion 31. For example, the second throttle valve 52 of the outdoor unit 20 is adjusted to a fully closed state, and the first on-off valve 55 is controlled to be switched to an open state. At this time, the refrigerant flow direction of the outdoor unit 20 defrosting the first portion 31 is as described above and will not be further described here.

[0348] For example, if the outdoor unit 20 includes a first temperature sensor 74, a second temperature sensor 75, and a third temperature sensor 78, when the air conditioning system 100 operates in heating mode, if the outdoor ambient temperature detected by the third temperature sensor 78 of any outdoor unit 20 is less than or equal to the first temperature threshold A, if either Te1 of the outdoor unit 20 or Te2 of the outdoor unit 20 is less than or equal to the second temperature threshold B, and if the air conditioning system 100 has been operating in heating mode for a first set duration, then the air conditioning system 100 is determined to meet the defrost condition. The values ​​of the first temperature threshold A, the second temperature threshold B, and the first set duration are as described above and are not further described.

[0349] In step S4B, it is determined whether the air conditioning system meets the first defrost mode end condition.

[0350] If the air-conditioning system 100 does not meet the first defrost mode end condition, the process returns to step S3B; if the air-conditioning system 100 meets the first defrost mode end condition, the process goes to step S5B.

[0351] In step S5B, the air conditioning system is controlled to operate in the second defrost mode.

[0352] In this way, the air conditioning system can defrost at least one second portion 32. For example, the second on-off valve 54 of the outdoor unit 20 currently operating in the first defrost mode is controlled to be switched to a closed state, the second throttle valve 52 is adjusted to a throttled state, the third throttle valve 53 is adjusted to a fully closed state, the throttle assembly 56 is adjusted to a throttled state, the first on-off valve 55 is controlled to be switched to a closed state, and the first throttle valve 51 is adjusted to a throttled state. At this time, the refrigerant flow direction of the outdoor unit 20 defrosting the second portion 32 is as described above and will not be further described here.

[0353] For example, the second end of the fifth branch 45 of the outdoor unit 20 is connected to the second end of the second portion 32, and the second end of the first branch 41 is connected to the first end of the second portion 321. If the outdoor unit 20 includes the fourth temperature sensor 76, when the air conditioning system 100 operates in the first defrost mode, if Tg1 of at least one first portion 31 is greater than or equal to the third temperature threshold C and persists for a second set time period, the air conditioning system 100 is determined to have completed defrosting the at least one first portion 31, i.e., the air conditioning system 100 is determined to have met the first defrost mode termination condition. The third temperature threshold C and the second set time period are described above and will not be further elaborated.

[0354] In step S6B, it is determined whether the air conditioning system satisfies the second defrost mode end condition.

[0355] If the air-conditioning system 100 does not meet the second defrost mode end condition, the process returns to step S5B; if the air-conditioning system 100 meets the second defrost mode end condition, the process exits the second defrost mode and the process returns to step S1B.

[0356] At this time, the refrigerant flow direction of the outdoor unit 20 that defrosts the second part 32 is as described above and will not be repeated here.

[0357] In some embodiments, the air conditioning system 100 may also operate in other modes, such as air supply mode, after exiting the second defrost mode.

[0358] For example, the second end of the fifth branch 45 of the outdoor unit 20 is connected to the second end of the second portion 32, and the second end of the first branch 41 is connected to the first end of the second portion 321. If the outdoor unit 20 includes the fifth temperature sensor 77, when the air conditioning system 100 operates in the second defrost mode, if Tg2 of at least one second portion 32 is greater than or equal to the third temperature threshold C and persists for a second set time period, the air conditioning system 100 is determined to have completed defrosting the at least one second portion 32, i.e., the air conditioning system 100 is determined to have met the second defrost mode termination condition. The third temperature threshold C and the second set time period are as described above and are not further elaborated upon.

[0359] In some embodiments, referring to FIG. 34 , the defrost control method of the air-conditioning system 100 further includes steps S1C to S6C.

[0360] In step S1C, the air conditioning system is controlled to operate in a heating mode.

[0361] For example, when the air-conditioning system 100 operates in heating mode, the controller 40 controls the first valve port 61 of the reversing assembly 6 to be connected to the second valve port 62, and the third valve port 63 to be connected to the fourth valve port 64, controls the second on-off valve 54 to switch to the open state, adjusts the second throttle valve 52 to the throttling state, adjusts the third throttle valve 53 to the throttling state, adjusts the throttling assembly 56 to the fully closed state, controls the first on-off valve 55 to switch to the closed state, and adjusts the first throttle valve 51 to the fully closed state.

[0362] In step S2C, it is determined whether the air conditioning system meets the defrosting conditions.

[0363] If the air conditioning system 100 does not meet the defrost conditions, the process returns to step S1C. If the air conditioning system 100 meets the defrost conditions, the process proceeds to step S3C. The defrost conditions include the outdoor ambient temperature, the operating time of the air conditioning system 100, and the temperature of at least one of the first portion or the temperature of at least one of the second portion.

[0364] In step S3C, the air conditioning system is controlled to operate in the second defrost mode.

[0365] In this manner, the air conditioning system 100 can defrost at least one second portion 32. For example, the second on-off valve 54 of the outdoor unit 20 is controlled to be switched to a closed state, the third throttle valve 53 is adjusted to a closed state, the throttle assembly 56 is adjusted to a throttled state, and the first throttle valve 51 is adjusted to a throttled state. At this time, the refrigerant flow direction within the outdoor unit 20 defrosting the second portion 32 is as previously described and will not be further elaborated here. The method for determining whether the air conditioning system 100 has met the defrost mode termination conditions is as previously described and will not be further elaborated here.

[0366] In step S4C, it is determined whether the air conditioning system meets the second defrost mode end condition.

[0367] If the air conditioning system 100 does not meet the second defrost mode end condition, the process returns to step S3C. If the air conditioning system 100 meets the second defrost mode end condition, the process returns to step S5C. The process of determining whether the air conditioning system 100 meets the second defrost mode end condition is as described above and will not be repeated here.

[0368] In step S5C, the air conditioning system is controlled to operate in the first defrost mode.

[0369] In this manner, the air conditioning system can defrost at least one first portion 31. For example, the second on-off valve 54 of the outdoor unit 20 currently operating in the second defrost mode is switched to an open state, the second throttle valve 52 is adjusted to a fully closed state, the third throttle valve 53 is adjusted to a throttled state, the throttle assembly 56 is adjusted to a fully closed state, the first on-off valve 55 is switched to an open state, and the first throttle valve 51 is adjusted to a fully closed state. At this point, the refrigerant flow direction of the outdoor unit 20 defrosting the first portion 31 is as previously described and will not be further elaborated here.

[0370] In step S6C, it is determined whether the air conditioning system meets the first defrost mode end condition.

[0371] If the air conditioning system 100 does not meet the first defrost mode termination condition, the process returns to step S5C. If the air conditioning system meets the first defrost mode termination condition, the process exits the first defrost mode and returns to step S1C. The process of determining whether the air conditioning system 100 meets the first defrost mode termination condition is as described above and will not be repeated here.

[0372] For example, the second throttle valve 52 of the outdoor unit 20 currently operating in the first defrost mode is adjusted to the throttling state, and the first on-off valve 55 is controlled to switch to the closed state. At this time, the refrigerant flow direction of the outdoor unit 20 defrosting the second part 32 is as described above and will not be repeated here.

[0373] In some embodiments, the air conditioning system 100 can also operate in other modes, such as a ventilation mode, after exiting the first defrost mode. In ventilation mode, the compressor operates, and neither the indoor heat exchanger nor the outdoor heat exchanger components exchange heat with the air. The indoor fan 102 operates to supply air to the room, thereby increasing indoor air flow.

[0374] The beneficial technical effects of the defrost control method of the air-conditioning system 100 provided in some embodiments of the present disclosure are the same as the beneficial technical effects of the air-conditioning system 100 provided in some embodiments of the present disclosure, and will not be repeated here.

[0375] In some embodiments, as shown in FIG35 , the air conditioning system 100 includes multiple outdoor units 20. FIG35 illustrates the defrost control method using two outdoor units 20 as an example. The defrost control method includes steps S10A to S60A.

[0376] In step S10A, the air conditioning system is controlled to operate in a heating mode.

[0377] For example, when the air-conditioning system 100 operates in heating mode, the first valve port 61 of the control reversing component 6 of each outdoor unit 20 is controlled to be connected to the second valve port 62, the third valve port 63 is controlled to be connected to the fourth valve port 64, the second on-off valve 54 is controlled to switch to the open state, the second throttle valve 52 is adjusted to the throttling state, the third throttle valve 53 is adjusted to the throttling state, the throttling component 56 is adjusted to the fully closed state, the first on-off valve 55 is controlled to switch to the closed state, and the first throttle valve 51 is adjusted to the fully closed state.

[0378] In step S20A, it is determined whether the air conditioning system meets the defrosting conditions.

[0379] If the air-conditioning system 100 does not meet the defrost condition, the process returns to step S10A; if the air-conditioning system 100 meets the defrost condition, the process goes to step S30A.

[0380] In step S30A, the air conditioning system is controlled to operate in the first defrost mode.

[0381] In this way, the air conditioning system 100 can simultaneously defrost the first section 31 of the first outdoor unit 20 and the first section 31 of the second outdoor unit 20. For example, the second throttle valve 52 of each outdoor unit 20 is adjusted to a fully closed state, and the first on-off valve 55 is controlled to be switched to an open state. At this time, the refrigerant flow direction of the outdoor unit 20 defrosting the first section 31 is as described above and will not be repeated here.

[0382] In step S40A, it is determined whether the air conditioning system meets the first defrost mode end condition.

[0383] If the air conditioning system 100 does not meet the first defrost mode end condition, the process returns to step S30A. If the air conditioning system 100 meets the first defrost mode end condition, the process returns to step S50A. The process of determining whether the air conditioning system 100 meets the first defrost mode end condition is as described above and will not be repeated here.

[0384] In step S50A, the air conditioning system 100 is controlled to operate in the second defrost mode.

[0385] In this way, the air conditioning system 100 can simultaneously defrost the second section 32 of the first outdoor unit 20 and the second section 32 of the second outdoor unit 20. For example, the second on-off valve 54 of each outdoor unit 20 is controlled to be switched to a closed state, the second throttle valve 52 is adjusted to a throttled state, the third throttle valve 53 is adjusted to a fully closed state, the throttle assembly 56 is adjusted to a throttled state, the first on-off valve 55 is controlled to be switched to a closed state, and the first throttle valve 51 is adjusted to a throttled state. At this time, the refrigerant flow direction of the outdoor unit 20 defrosting the second section 32 is as described above and will not be further described here.

[0386] In step S60A, it is determined whether the air conditioning system meets the second defrost mode end condition.

[0387] If the air conditioning system 100 does not meet the second defrost mode termination condition, the process returns to step S50A. If the air conditioning system 100 meets the second defrost mode termination condition, the process exits the second defrost mode and returns to step S10A. The determination of whether the air conditioning system 100 meets the second defrost mode termination condition is as described above and will not be repeated here.

[0388] At this time, the refrigerant flow direction of the outdoor unit 20 that defrosts the second part 32 is as described above and will not be repeated here. In other embodiments, the air conditioning system 100 can also operate in other modes, such as the air supply mode, after exiting the second defrost mode.

[0389] In some embodiments, referring to FIG36 , the air conditioning system 100 includes multiple outdoor units 20. FIG36 illustrates the defrost control method using two outdoor units 20 as an example. The defrost control method includes steps S10B to S60B.

[0390] In step S10B, the air conditioning system is controlled to operate in a heating mode.

[0391] For example, when the air-conditioning system 100 is controlled to operate in heating mode, the first valve port 61 of the reversing assembly 6 of each outdoor unit 20 is controlled to be connected to the second valve port 62, the third valve port 63 is controlled to be connected to the fourth valve port 64, the second on-off valve 54 is controlled to switch to the open state, the second throttle valve 52 is adjusted to the throttling state, the third throttle valve 53 is adjusted to the throttling state, the throttling assembly 56 is adjusted to the fully closed state, the first on-off valve 55 is controlled to switch to the closed state, and the first throttle valve 51 is adjusted to the fully closed state.

[0392] In step S20B, it is determined whether the air conditioning system meets the defrosting conditions.

[0393] If the air-conditioning system 100 does not meet the defrost condition, the process returns to step S10B; if the air-conditioning system 100 meets the defrost condition, the process goes to step S30B.

[0394] In step S30B, the air conditioning system is controlled to operate in the second defrost mode.

[0395] In this way, the air conditioning system can simultaneously defrost the second section 32 of the first outdoor unit 20 and the second section 32 of the second outdoor unit 20. For example, the second on-off valve 54 of each outdoor unit 20 is controlled to be switched to the closed state, the third throttle valve 53 is adjusted to the closed state, the throttle assembly 56 is adjusted to the throttle state, and the first throttle valve 51 is adjusted to the throttle state. At this time, the refrigerant flow direction within the outdoor unit 20 defrosting the second section 32 is as described above and will not be repeated here.

[0396] In step S40B, it is determined whether the air conditioning system meets the second defrost mode end condition.

[0397] If the air conditioning system 100 does not meet the second defrost mode end condition, the process returns to step S30B. If the air conditioning system 100 meets the second defrost mode end condition, the process returns to step S50B. The process of determining whether the air conditioning system 100 meets the second defrost mode end condition is as described above and will not be repeated here.

[0398] In step S50B, the air conditioning system 100 is controlled to operate in the first defrost mode.

[0399] In this way, the air conditioning system can simultaneously defrost the first section 31 of the first outdoor unit 20 and the first section 31 of the second outdoor unit 20. For example, the second on-off valve 54 of each outdoor unit 20 is controlled to be switched to an open state, the second throttle valve 52 is adjusted to a fully closed state, the third throttle valve 53 is adjusted to a throttled state, the throttle assembly 56 is adjusted to a fully closed state, the first on-off valve 55 is controlled to be switched to an open state, and the first throttle valve 51 is adjusted to a fully closed state. At this time, the refrigerant flow direction of the outdoor unit 20 defrosting the first section 31 is as described above and will not be further described here.

[0400] In step S60B, it is determined whether the air conditioning system 100 satisfies the first defrost mode end condition.

[0401] If the air conditioning system 100 does not meet the first defrost mode termination condition, the process returns to step S50B. If the air conditioning system 100 meets the first defrost mode termination condition, the process exits the first defrost mode and returns to step S10B. The determination of whether the air conditioning system 100 meets the first defrost mode termination condition is as described above and will not be repeated here.

[0402] At this time, the refrigerant flow direction of the outdoor unit 20 that defrosts the second part 32 is as described above and will not be repeated here.

[0403] In some embodiments, the air conditioning system 100 may also operate in other modes, such as air supply mode, after exiting the first defrost mode.

[0404] In some embodiments, as shown in FIG37 , the air conditioning system 100 includes multiple outdoor units 20. FIG37 illustrates the defrost control method using two outdoor units 20 as an example. The defrost control method includes steps S100A to S1000A.

[0405] In step S100A, the air conditioning system 100 is controlled to operate in a heating mode.

[0406] For example, when controlling the air-conditioning system 100 to operate in heating mode, the first valve port 61 of the control reversing assembly 6 of each outdoor unit 20 is controlled to be connected to the second valve port 62, the third valve port 63 is controlled to be connected to the fourth valve port 64, the second on-off valve 54 is controlled to switch to the open state, the second throttle valve 52 is adjusted to the throttling state, the third throttle valve 53 is adjusted to the throttling state, the throttling assembly 56 is adjusted to the fully closed state, the first on-off valve 55 is controlled to switch to the closed state, and the first throttle valve 51 is adjusted to the fully closed state.

[0407] In step S200A, it is determined whether the air conditioning system 100 meets the defrosting condition.

[0408] If the air-conditioning system 100 does not meet the defrost condition, the process returns to step S100A; if the air-conditioning system 100 meets the defrost condition, the process goes to step S300A.

[0409] In step S300A, the air conditioning system 100 is controlled to operate in a first defrosting mode to defrost a first part of a first outdoor unit.

[0410] For example, the second throttle valve 52 of the first outdoor unit 20 is adjusted to a fully closed state, and the first on-off valve 55 is controlled to be switched to an open state. At this time, the refrigerant flow direction of the first outdoor unit 20 is as described above and will not be repeated here.

[0411] In step S400A, it is determined whether the air conditioning system meets the first defrost mode end condition.

[0412] If the air conditioning system does not meet the first defrost mode end condition, the process returns to step S300A. If the air conditioning system meets the first defrost mode end condition, the process returns to step S500A. The process of determining whether the air conditioning system 100 meets the first defrost mode end condition is as described above and will not be repeated here.

[0413] In step S500A, the air conditioning system 100 is controlled to operate in the second defrost mode, defrosting the second portion of the first outdoor unit. For example, the second on-off valve 54 of the first outdoor unit 20 is controlled to be switched to the closed state, the second throttle valve 52 is adjusted to the throttled state, the third throttle valve 53 is adjusted to the fully closed state, the throttle assembly 56 is adjusted to the throttled state, the first on-off valve 55 is controlled to be switched to the closed state, and the first throttle valve 51 is adjusted to the throttled state. At this point, the refrigerant flow direction of the first outdoor unit 20 is as described above and will not be further described here.

[0414] In step S600A, it is determined whether the air conditioning system meets the second defrost mode end condition.

[0415] If the air conditioning system does not meet the second defrost mode end condition, the process returns to step S500A. If the air conditioning system meets the second defrost mode end condition, the process returns to step S700A. The process of determining whether the air conditioning system 100 meets the second defrost mode end condition is as described above and will not be repeated here.

[0416] In step S700A, the air conditioning system is controlled to operate in a first defrost mode to defrost the first part of the second outdoor unit.

[0417] For example, control the second on-off valve 54 of the first outdoor unit 20 to switch to the open state, adjust the third throttle valve 53 to the throttling state, adjust the throttling assembly 56 to the fully closed state, and adjust the first throttle valve 51 to the fully closed state; adjust the second throttle valve 52 of the second outdoor unit 20 to the fully closed state, and control the first on-off valve 55 to switch to the open state.

[0418] It is understandable that when the air conditioning system is controlled to defrost the first part 31 of the second outdoor unit 20, the first outdoor unit 20 and the indoor heat exchanger 101 are controlled to operate in the heating mode. At this time, the refrigerant flow direction of the second outdoor unit 20 is as described above and will not be repeated here.

[0419] In step S800A, it is determined whether the air conditioning system meets the first defrost mode end condition.

[0420] If the air-conditioning system does not meet the first defrost mode end condition, return to step S700A; if the air-conditioning system meets the first defrost mode end condition, go to step S900A.

[0421] The air-conditioning system 100 satisfies the termination condition of the first defrost mode as described above and will not be repeated here.

[0422] In step S900A, the air conditioning system is controlled to operate in a second defrost mode to defrost the second part of the second outdoor unit.

[0423] For example, the second on-off valve 54 of the second outdoor unit 20 is controlled to be switched to the closed state, the second throttle valve 52 is adjusted to the throttle state, the third throttle valve 53 is adjusted to the fully closed state, the throttle assembly 56 is adjusted to the throttle state, the first on-off valve 55 is controlled to be switched to the closed state, and the first throttle valve 51 is adjusted to the throttle state. At this time, the refrigerant flow direction of the second outdoor unit 20 is as described above and will not be repeated here.

[0424] In step S1000A, it is determined whether the air conditioning system meets the second defrost mode end condition.

[0425] If the air conditioning system does not meet the second defrost mode end condition, the process returns to step S900A. If the air conditioning system meets the second defrost mode end condition, the process returns to step S1000A. The conditions for the air conditioning system 100 to meet the second defrost mode end condition are as described above and will not be repeated here.

[0426] In some embodiments, as shown in FIG38 , the air conditioning system 100 includes multiple outdoor units 20. FIG38 illustrates the defrost control method using two outdoor units 20 as an example. The defrost control method includes steps S100B to S1000B.

[0427] S100B controls the air conditioning system to operate in heating mode.

[0428] For example, when the air-conditioning system 100 operates in heating mode, the first valve port 61 of the control reversing component 6 of each outdoor unit 20 is controlled to be connected to the second valve port 62, the third valve port 63 is controlled to be connected to the fourth valve port 64, the second on-off valve 54 is controlled to switch to the open state, the second throttle valve 52 is adjusted to the throttling state, the third throttle valve 53 is adjusted to the throttling state, the throttling component 56 is adjusted to the fully closed state, the first on-off valve 55 is adjusted to the closed state, and the first throttle valve 51 is adjusted to the fully closed state.

[0429] S200B, determining whether the air conditioning system meets the defrosting conditions.

[0430] If the air-conditioning system 100 does not meet the defrost condition, the process returns to step S100B; if the air-conditioning system 100 meets the defrost condition, the process goes to step S300B.

[0431] S300B, controlling the air conditioning system to operate in a second defrost mode, and defrosting the second part of the first outdoor unit.

[0432] For example, the second on-off valve 54 of the first outdoor unit 20 is controlled to be switched to the closed state, the third throttle valve 53 is adjusted to the closed state, the throttle assembly 56 is adjusted to the throttle state, and the first throttle valve 51 is adjusted to the throttle state. At this time, the refrigerant flow direction in the first outdoor unit 20 is as described above and will not be repeated here.

[0433] S400B: Determine whether the air conditioning system meets the second defrost mode termination condition.

[0434] If the air conditioning system does not meet the second defrost mode end condition, the process returns to step S300B. If the air conditioning system meets the second defrost mode end condition, the process returns to step S500B. The conditions for the air conditioning system 100 to meet the second defrost mode end condition are as described above and will not be repeated here.

[0435] S500B: Control the air-conditioning system to operate in the first defrost mode, and defrost the first part of the first outdoor unit.

[0436] For example, the second on-off valve 54 of the first outdoor unit 20 is controlled to be switched to an open state, the second throttle valve 52 is adjusted to a fully closed state, the third throttle valve 53 is adjusted to a throttle state, the throttle assembly 56 is adjusted to a fully closed state, the first on-off valve 55 is controlled to be switched to an open state, and the first throttle valve 51 is adjusted to a fully closed state. At this time, the refrigerant flow direction of the first outdoor unit 20 is as described above and will not be repeated here.

[0437] S600B, determining whether the air conditioning system meets the first defrost mode termination condition.

[0438] If the air conditioning system does not meet the first defrost mode end condition, the process returns to step S500B. If the air conditioning system meets the first defrost mode end condition, the process returns to step S700B. The air conditioning system 100 meets the first defrost mode end condition as described above and will not be repeated here.

[0439] S700B: Control the air conditioning system 100 to operate in the second defrost mode to defrost the second part of the second outdoor unit.

[0440] For example, the second throttle valve 52 of the first outdoor unit 20 is adjusted to the throttle state, and the first on-off valve 55 is controlled to switch to the closed state. The second on-off valve 54 of the second outdoor unit 20 is controlled to switch to the closed state, the third throttle valve 53 is adjusted to the closed state, the throttle assembly 56 is adjusted to the throttle state, and the first throttle valve 51 is adjusted to the throttle state. At this time, the refrigerant flow direction in the second outdoor unit 20 is as described above and will not be repeated here.

[0441] It is understandable that when the air conditioning system 100 is controlled to defrost the second part 32 of the second outdoor unit 20 , the first outdoor unit 20 and the indoor heat exchanger 101 are controlled to operate in the heating mode.

[0442] S800B, determining whether the air conditioning system meets the second defrost mode end condition.

[0443] If the air conditioning system does not meet the second defrost mode end condition, the process returns to step S700B. If the air conditioning system meets the second defrost mode end condition, the process returns to step S900B. The conditions for the air conditioning system 100 to meet the second defrost mode end condition are as described above and will not be repeated here.

[0444] S900B: Controls the air conditioning system to run the first defrost mode and defrosts the first part of the second outdoor unit.

[0445] For example, the second on-off valve 54 of the second outdoor unit 20 is controlled to be switched to an open state, the second throttle valve 52 is adjusted to a fully closed state, the third throttle valve 53 is adjusted to a throttle state, the flow assembly 56 is adjusted to a fully closed state, the first on-off valve 55 is controlled to be switched to an open state, and the first throttle valve 51 is adjusted to a fully closed state. At this time, the refrigerant flow direction of the outdoor unit 20 defrosting the first part 31 is as described above and will not be repeated here.

[0446] S1000B: Determine whether the air conditioning system meets the first defrost mode termination condition.

[0447] If the air conditioning system does not meet the first defrost mode end condition, the process returns to step S900B. If the air conditioning system meets the first defrost mode end condition, the process returns to step S100B. The air conditioning system 100 meets the first defrost mode end condition as described above and will not be repeated here.

[0448] The above mainly introduces the solutions provided by some embodiments of the present disclosure from the perspective of the air-conditioning system 100. It can be understood that in order to realize the above functions, the air-conditioning system 100 includes hardware structures and / or software modules corresponding to the execution of each function. It should be easily appreciated by those skilled in the art that, in combination with the algorithm steps of each example described in the embodiments disclosed herein, the present disclosure can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present disclosure.

[0449] Those skilled in the art will understand that the scope of the present disclosure is not limited to the above specific embodiments, and that certain elements of the embodiments may be modified and replaced without departing from the spirit of the present disclosure. The scope of the present disclosure is limited by the appended claims.

Claims

1. An air conditioning system, comprising: An indoor unit, including an indoor heat exchanger; as well as, Outdoor unit, including: A compressor, including a suction port and a discharge port; The first branch; and An outdoor heat exchanger assembly comprises a first part and a second part, wherein the first part is in communication with the second part through the first branch; Wherein, when the air conditioning system operates in a defrost-free mode, the indoor heat exchanger is connected to the exhaust port of the compressor and to the second part; the first part is connected to the air intake port of the compressor; The first part is located on one side of the second part, and in a plane perpendicular to a direction from the first part to the second part, projections of at least part of the first part and at least part of the second part overlap, and the second part is configured to exchange heat with the first part.

2. The air conditioning system according to claim 1, wherein: The first end of the first branch is in communication with the first end of the second portion, and the second end of the first branch is in communication with the second end of the first portion; When the air-conditioning system operates in the defrost-free mode, the refrigerant in the compressor enters the indoor heat exchanger and the second part in sequence from the exhaust port, heats the second part, and returns to the compressor through the first part and the intake port.

3. The air conditioning system according to claim 1 or 2, wherein: The outdoor unit further comprises: an outdoor fan, wherein the second part and the first part are arranged in sequence along the direction of the airflow generated when the outdoor fan is in operation; The outdoor unit is configured to operate and generate airflow when the air conditioning system operates in a defrost-free mode, so as to blow air near the second part toward the first part, so that heat of the second part is transferred to the first part.

4. The air conditioning system according to any one of claims 1 to 3, wherein: The first part is located directly above the second part; or the first part is located directly below the second part.

5. The air conditioning system according to any one of claims 1 to 4, wherein: The outdoor unit further comprises: a reversing assembly, wherein a first valve port of the reversing assembly is communicated with the exhaust port, a second valve port of the reversing assembly is communicated with a first end of the indoor heat exchanger, a third valve port of the reversing assembly is communicated with a first end of the first part and a first end of the second part respectively, and a fourth valve port of the reversing assembly is communicated with the air intake port; a second branch, wherein a first end of the second branch is in communication with a second end of the first portion, and a second end of the second branch is in communication with a second end of the indoor heat exchanger; a third branch, a first end of the third branch being in communication with the second end of the second portion, and a second end of the third branch being in communication with the second end of the indoor heat exchanger; a second throttle valve, disposed on the second branch; A third throttle valve is provided in the third branch; and The second on-off valve is arranged between the third valve port and the first end of the second part.

6. The air conditioning system according to any one of claims 1 to 5, wherein: The outdoor unit further comprises a fourth branch; a first end of the fourth branch is communicated with the exhaust port of the compressor, and a second end of the fourth branch is communicated with the second end of the first part; When the air conditioning system operates in defrost mode, the fourth branch is configured to allow the refrigerant in the compressor to enter the first part through the exhaust port to heat the first part and return to the compressor through the intake port.

7. The air conditioning system according to any one of claims 1 to 6, wherein: The outdoor unit further comprises a fifth branch, a first end of the fifth branch is connected to the exhaust port, and a second end of the fifth branch is connected to the second end of the second part; When the air conditioning system operates in defrost mode, the fifth branch is configured to allow the refrigerant in the compressor to enter the second part through the exhaust port to heat the second part and return to the compressor through the intake port.

8. The air conditioning system according to any one of claims 1 to 7, wherein: The air conditioning system further comprises: a controller, The controller is configured to: If the air conditioning system meets the defrost-free mode start condition, controlling the first branch circuit to be turned on so that the refrigerant of the compressor of the outdoor unit heats the second part, and the second part heats the first part; If the air-conditioning system meets the defrost-free mode termination condition, the air-conditioning system operates in a preset working mode.

9. The air conditioning system according to claim 8, wherein: The controller is configured to: if the air conditioning system meets the defrost-free mode start condition, adjust the first suction superheat Tssh1 of the compressor to be greater than or equal to a first threshold d, and adjust the exhaust superheat Tdsh of the compressor to be greater than or equal to a second threshold e; Among them, 0℃≤d<e, Tssh1=Tg1-Tcps, and Tdsh=Td-Tcpd; Tg1 is the temperature of the first end of the first part, Td is the exhaust temperature of the exhaust port of the compressor, Tcps is the saturation temperature corresponding to the suction pressure of the compressor, and Tcpd is the saturation temperature corresponding to the exhaust pressure of the compressor.

10. The air conditioning system according to claim 9, wherein: The value range of d is: 0℃≤d<3℃, 3℃≤d<6℃ or 6℃≤d≤10℃; and / or, The value range of e is: 20℃≤e<28℃, 28℃≤e<36℃ or 36℃≤e≤40℃.

11. The air conditioning system according to any one of claims 8 to 10, wherein: The defrost-free mode start condition includes: a minimum value Tamin of the temperature of the outdoor environment is less than or equal to a third threshold a, a minimum value Te1min of the temperature of the second end of the first part or a minimum value Te2min of the temperature of the second end of the second part is less than or equal to a fourth threshold b, and a cumulative operation time of the air-conditioning system in the heating mode reaches a fifth threshold c; Among them, -7℃ <a<7℃,b≤0℃,10min≤c。 12. The air conditioning system according to claim 11, wherein: -7℃ <a<7℃,b=0℃,10min≤c<20min; Or, -7°C <a<7℃,-5℃≤b<0℃,20min≤c<30min; Or, -7°C <a<7℃,b<-5℃,c≥30min。 13. The air conditioning system according to claim 9 or 10, wherein: The controller is also configured to: if the air-conditioning system meets the defrost-free mode termination condition, control the fourth branch to be turned on so that the refrigerant in the compressor enters the first part through the fourth branch from the exhaust port and heats the first part.

14. The air conditioning system according to claim 13, wherein: The controller is also configured to: Before the air conditioning system satisfies the defrosting mode end condition and the controller controls the fourth branch to conduct, adjust the second suction superheat degree Tssh2 of the compressor so that Tssh2≥d; and, Adjust the discharge superheat degree Tdsh of the compressor so that Tdsh≥e; Wherein, Tssh2 = Tg2 - Tcps, and Tg2 is the temperature at the first end of the second part.

15. The air conditioning system according to any one of claims 8 to 13, wherein: The indoor unit includes an indoor fan; the controller is further configured to: If the air conditioning system satisfies the defrosting mode start condition, compare the minimum value Pdmin of the discharge pressure of the compressor with a first threshold pressure h and a second threshold pressure I respectively, and obtain the comparison result; If Pdmin≥h, control the air volume gear of the indoor fan to be a first preset air volume gear; If Pdmin < I, control the indoor fan to stop running; and, If I≤Pdmin < h, control the air volume gear of the indoor fan to be a second preset air volume gear; Wherein, I < h, and the rotation speed of the indoor fan at the second preset air volume gear is less than the maximum rotation speed of the indoor fan.

16. The air conditioning system according to claim 15, wherein: 1.5MPa≤h≤2MPa, 1MPa≤I≤1.5MPa, and the rotation speed of the indoor fan at the second preset air volume gear is less than half of the maximum rotation speed of the indoor fan.

17. The air conditioning system according to any one of claims 8 to 16, wherein: The indoor unit includes an indoor fan; the controller is further configured to: If the air conditioning system satisfies the defrosting mode start condition, compare the minimum value Tomin of the air outlet temperature of the indoor unit with a first threshold temperature M1 and a second threshold temperature N1 respectively, and obtain the comparison result; Compare the minimum value Tlmin of the liquid pipe temperature of the indoor heat exchanger with a third threshold temperature M2 and a fourth threshold temperature N2 respectively, and obtain the comparison result; If Tomin≥M1 or Tlmin≥M2, control the air volume gear of the indoor fan to be a first preset air volume gear; If Tomin < N1 and Tlmin < N2, control the indoor fan to stop running; and, If N1≤Tomin < M1 or N2≤Tlmin < M2, control the air volume gear of the indoor fan to be a second preset air volume gear; Wherein, N1 < M1, N2 < M2, and the rotation speed of the indoor fan at the second preset air volume gear is less than the maximum rotation speed of the indoor fan.

18. The air conditioning system according to claim 17, wherein: 5℃≤M1≤35℃, 15℃≤N1≤25℃, 20℃≤M2≤40℃, 10℃≤N2≤25℃; The rotation speed of the indoor fan at the second preset air volume gear is less than half of the maximum rotation speed of the indoor fan.

19. An air conditioning system, comprising: Outdoor unit, including: A compressor, including a suction port and a discharge port; A commutation assembly, including a first valve port, a second valve port, a third valve port, and a fourth valve port, wherein the first valve port is communicated with the discharge port, and the fourth valve port is communicated with the suction port; An outdoor heat exchanger assembly, including a first part and a second part; the first end of the first part is communicated with the third valve port; A fourth branch, the first end of the fourth branch is communicated with the discharge port, and the second end of the fourth branch is communicated with the second end of the first part; a fifth branch and a first branch, wherein the first end of the fifth branch is connected to the exhaust port, and the first end of the first branch is connected to the second end of the first part; one of the second end of the fifth branch and the second end of the first branch is connected to the second end of the second part, and the other is connected to the first end of the second part; and A first on-off valve, a second on-off valve, a first throttle valve, a second throttle valve, a third throttle valve and a throttle assembly, wherein the first on-off valve is arranged on the fourth branch, the second on-off valve is arranged between the first end of the second part and the third valve port, the first throttle valve is arranged on the first branch, and the throttle assembly is arranged on the fifth branch; an indoor heat exchanger, wherein the first end of the indoor heat exchanger is connected to the second valve port; the second throttle valve is arranged between the second end of the indoor heat exchanger and the second end of the first part, and the third throttle valve is arranged between the second end of the indoor heat exchanger and the second end of the second part; and A controller is electrically connected to the indoor heat exchanger and the outdoor unit, and is configured as follows: When the air conditioning system is controlled to defrost the first part of the outdoor unit, the first valve port and the second valve port of the outdoor unit are controlled to be connected, the third valve port and the fourth valve port are controlled to be connected, the first on-off valve and the second on-off valve are opened, the first throttle valve and the throttle assembly are fully closed, and the third throttle valve is throttled; and, When the air-conditioning system is controlled to defrost the second part of the outdoor unit, the first valve port and the second valve port of the outdoor unit are controlled to be connected, the third valve port and the fourth valve port are controlled to be connected, the first throttle valve, the second throttle valve and the throttling assembly are throttled, and the first on-off valve and the second on-off valve are closed.

20. The air conditioning system according to claim 19, wherein: The outdoor unit further comprises: a first temperature sensor, disposed at the second end of the first portion and configured to detect a temperature Te1 of the second end of the first portion; a second temperature sensor disposed at the second end of the second portion and configured to detect a temperature Te2 of the second end of the second portion; and, A third temperature sensor is configured to detect an outdoor ambient temperature Ta; The controller is electrically connected to the first temperature sensor, the second temperature sensor and the third temperature sensor, and the controller is further configured as: When the air-conditioning system operates in a heating mode, if the outdoor ambient temperature detected by the third temperature sensor of the outdoor unit is less than or equal to a first temperature threshold, any one of Te1 of the outdoor unit and Te2 of the outdoor unit is less than or equal to a second temperature threshold, and the continuous operation time of the air-conditioning system in the heating mode reaches a first set time, it is determined that the air-conditioning system meets the defrosting condition; and Controlling the air conditioning system to operate in a first defrost mode or a second defrost mode; When the air-conditioning system operates in the first defrost mode, the air-conditioning system defrosts the first part of the outdoor unit, and when the air-conditioning system operates in the second defrost mode, the air-conditioning system defrosts the second part of the outdoor unit.

21. The air conditioning system according to claim 20, wherein: The second end of the fifth branch is connected to the second end of the second part, and the second end of the first branch is connected to the first end of the second part; The outdoor unit and the controller also satisfy at least one of the following: The outdoor unit further includes a fourth temperature sensor, which is disposed at the first end of the first part and is configured to detect a temperature Tg1 of the first end of the first part; the controller is electrically connected to the fourth temperature sensor and is also configured to Set as follows: when the air-conditioning system runs in the first defrost mode, if Tg1 of the first part of the outdoor unit is greater than or equal to a third temperature threshold and lasts for a second set time, it is determined that the air-conditioning system has completed defrosting the first part of the outdoor unit, and the air-conditioning system is controlled to exit the first defrost mode; or, The outdoor unit also includes a fifth temperature sensor, which is arranged at the first end of the second part and is configured to detect the temperature Tg2 of the first end of the second part; the controller is electrically connected to the fifth temperature sensor, and is also configured to: when the air-conditioning system runs the second defrost mode, if Tg2 of the second part of the outdoor unit is greater than or equal to a third temperature threshold and lasts for a second set time, it is determined that the air-conditioning system has completed defrosting the second part of the outdoor unit, and the air-conditioning system is controlled to exit the second defrost mode.

22. The air conditioning system according to claim 21, wherein: The air conditioning system also satisfies at least one of the following: The controller is further configured to: when the air conditioning system defrosts the second part of the outdoor unit, adjust the first throttle valve flow rate of the outdoor unit so that ΔT satisfies a first preset condition, wherein ΔT=Te2-Tg2; the first preset condition includes: ΔT is greater than or equal to 10°C and less than or equal to a fourth temperature threshold; and / or, The outdoor unit further includes a first pressure sensor, which is disposed at the suction port and is configured to detect the suction pressure Ps of the compressor; The controller is electrically connected to the first pressure sensor and is further configured to: when the air conditioning system defrosts the first part of the outdoor unit, obtain the maximum suction pressure Psmax of the suction port of the outdoor unit; and When the air conditioning system defrosts the second part of the outdoor unit, the flow rate of the throttling component of the outdoor unit is adjusted so that P2 satisfies a second preset condition, where P2 is a saturation pressure corresponding to (K1*Tg2+K2*Te2); Among them, the second preset condition is: P2≥Psmax, 0.5≤K1<0.7 or 0.7≤K1≤0.9, 0.1≤K2<0.3 or 0.3≤K2≤0.

5.

23. The air conditioning system according to claim 20 or 21, wherein: include: N outdoor units, the N outdoor units are connected in parallel between the first end and the second end of the indoor heat exchanger, and N≥2; The controller is also configured to: When controlling the air conditioning system to operate the first defrost mode, controlling the air conditioning system to defrost the first parts of the N outdoor units; as well as, When the air conditioning system is controlled to operate the second defrost mode, the air conditioning system is controlled to defrost the second parts of the N outdoor units.

24. The air conditioning system according to any one of claims 20 to 23, wherein: include: N outdoor units, the N outdoor units are connected in parallel between the first end and the second end of the indoor heat exchanger, and N≥2; The controller is also configured to: Obtaining the defrosting order of the N outdoor units; as well as, When controlling the air conditioning system to alternately operate the first defrost mode and the second defrost mode, so as to defrost the outdoor heat exchanger assemblies of the N outdoor units according to the defrost order; When the air conditioning system is controlled to operate in the first defrost mode, the air conditioning system is controlled to defrost the first part of one of the outdoor units; When the air conditioning system is controlled to operate the second defrost mode, the air conditioning system is controlled to defrost the second portion of one of the outdoor units.

25. A defrosting control method for an air conditioning system, wherein: The defrost control method is applied to the air conditioning system according to any one of claims 19 to 24, The defrost control method satisfies one of the following: The defrost control method comprises: When the air-conditioning system operates in a heating mode, if the air-conditioning system meets a defrosting condition, the air-conditioning system is controlled to operate in a first defrosting mode to defrost the first part of the outdoor unit, wherein the defrosting condition includes an outdoor ambient temperature, an operating time of the air-conditioning system, and a temperature of the first part of the outdoor unit or a temperature of the second part of the outdoor unit; If the air conditioning system has finished defrosting the first part of the outdoor unit, controlling the air conditioning system to exit the first defrost mode and run the second defrost mode to defrost the second part of the outdoor unit; If the air conditioning system has completed defrosting the second part of the outdoor unit, the air conditioning system is controlled to exit the second defrosting mode. Mode; or, The defrost control method comprises: When the air-conditioning system operates in a heating mode, if the air-conditioning system meets a defrost condition, controlling the air-conditioning system to operate in a second defrost mode to defrost the second part of the outdoor unit, wherein the defrost condition includes an outdoor ambient temperature, an operating time of the air-conditioning system, and a temperature of at least one of the first part or a temperature of at least one of the second part; If the air conditioning system has finished defrosting the second part of the outdoor unit, controlling the air conditioning system to exit the second defrost mode and operate the first defrost mode to defrost the first part of the outdoor unit; If the air-conditioning system has completed defrosting the first part of the outdoor unit, the air-conditioning system is controlled to exit the first defrosting mode.

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