A multi-split air conditioning system

Abstract

The embodiment of the present disclosure discloses a multi-split air conditioning system, relates to the technical field of air conditioning, and aims to improve the heating efficiency of the multi-split air conditioning system. The multi-split air conditioning system comprises a plurality of parallel outdoor units, a plurality of parallel indoor units and a controller. The controller is configured to: determine whether the outdoor unit meets the defrosting condition; set the outdoor unit meeting the defrosting condition as a target outdoor unit; determine whether the outlet temperature of the outdoor heat exchanger in the target outdoor unit is greater than or equal to a first preset temperature; if not, control the target outdoor unit to perform a reverse defrosting mode; control the indoor fan of the indoor unit to be inoperative; control the defrosting branch to block the compressor and the outdoor heat exchanger; if yes, control the target outdoor unit to perform a bypass defrosting mode by using the defrosting branch; control the wind speed of the indoor fan in the indoor unit to be less than or equal to a first preset wind speed; and control the defrosting branch to connect the compressor and the outdoor heat exchanger, so as to defrost the outdoor heat exchanger. The present disclosure is used for adjusting temperature.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of air conditioning, in particular to a multi-split air conditioning system. BACKGROUND

[0002] With the development of economic society, air conditioners can bring people a better experience, so they are more and more widely used in entertainment, home and work and other places.

[0003] The outdoor heat exchanger in the outdoor unit of the existing multi-split air conditioning system is prone to frosting after running in the heating mode for a period of time, resulting in the attenuation of the heating capacity of the multi-split air conditioning system. The existing defrosting technology generally adopts a reverse cycle mode to defrost the outdoor unit. When the outdoor heat exchanger is defrosted, the indoor heat exchanger is much lower than the indoor environment temperature, and the indoor fan does not blow air, which easily causes the indoor environment temperature to decrease, resulting in poor thermal comfort experience of the user. SUMMARY

[0004] Embodiments of the present disclosure provide a multi-split air conditioning system, which can continuously heat and the indoor fan blows air at a high temperature when the outdoor unit of the multi-split air conditioning system is defrosted.

[0005] To achieve the above-mentioned purpose, embodiments of the present disclosure adopt the following technical solutions:

[0006] Embodiments of the present disclosure provide a multi-split air conditioning system, which comprises a plurality of parallel-connected outdoor units, a plurality of parallel-connected indoor units and a controller. The outdoor unit comprises a compressor, an outdoor heat exchanger and a defrosting branch for connecting or blocking the compressor and the outdoor heat exchanger. The indoor unit comprises an indoor heat exchanger and an indoor fan for adjusting the air flow rate near the indoor heat exchanger. The controller is electrically connected to the outdoor unit and the indoor unit. The controller is configured to: determine whether the outdoor unit in the heating mode meets the defrosting condition; set the outdoor unit meeting the defrosting condition as a target outdoor unit; determine whether the outlet temperature of the outdoor heat exchanger in the target outdoor unit is greater than or equal to a first preset temperature; if not, control the target outdoor unit to perform a reverse defrosting mode; control the indoor fan of the indoor unit to not work; if yes, control the target outdoor unit to perform a bypass defrosting mode by using the defrosting branch; and control the defrosting branch to connect the compressor and the outdoor heat exchanger, so that part of the refrigerant enters the outdoor heat exchanger from the discharge port of the compressor through the defrosting branch, or the refrigerant enters the outdoor heat exchanger from the discharge port of the compressor, and part of the refrigerant discharged from the outdoor heat exchanger enters the suction port of the compressor through the defrosting branch, thereby defrosting the outdoor heat exchanger.

[0007] The multi-split air conditioning system provided by some embodiments of the present disclosure detects and judges the outlet temperature of the outdoor unit meeting the defrosting condition through the controller. For the target outdoor unit with the outlet temperature less than the first preset temperature, the controller controls the target outdoor unit to perform defrosting in the reverse defrosting mode and controls the indoor fan of the indoor unit to stop working. For the target outdoor unit with the outlet temperature greater than or equal to the first preset temperature, the controller controls the bypass defrosting mode of the defrosting branch, controls the passage between the compressor and the outdoor heat exchanger of the defrosting branch to be connected, and controls the indoor fan of the indoor unit to blow out air with a wind speed less than the first preset wind speed. Thus, different defrosting modes and control modes of the indoor fan are adopted according to different frosting conditions, which can improve the heating efficiency of the multi-split air conditioning system, make the user experience better heating comfort, and avoid the situation that the outlet temperature of the indoor unit is low when the target outdoor unit is defrosting, thereby affecting the heating effect of the multi-split air conditioning system. In addition, in the process of defrosting by the defrosting branch, the target outdoor unit can be defrosted alone without affecting the heating process of the outdoor unit connected in parallel with the target outdoor unit, so that uninterrupted and continuous heating effect of the multi-split air conditioning system can be achieved, and the influence of the defrosting process on the heating effect is avoided.

[0008] In some embodiments, the controller controls the wind speed of the indoor fan in the indoor unit to be less than or equal to the first preset wind speed, and the control is specifically configured as follows: obtaining the discharge pressure of the target outdoor unit; judging whether the discharge pressure is greater than or equal to a preset pressure; if not, controlling the indoor fan to stop blowing air; judging whether the target outdoor unit meets the defrosting end condition; if yes, releasing the control on the indoor fan; if yes, obtaining the outlet air temperature of the indoor unit every first preset time; the number of the indoor units is P, P≥1, and P is an integer; judging whether the outlet air temperature of each indoor unit is greater than or equal to a second preset temperature; if not, judging the number of indoor units with the outlet air temperature less than the second preset temperature; if the number of indoor units with the outlet air temperature less than the second preset temperature is 1, turning off the indoor fan of the indoor unit; if the number of indoor units with the outlet air temperature less than the second preset temperature is greater than 1, sorting the capacities of the indoor units, and turning off the indoor fan of the indoor unit with the smallest capacity; if yes, controlling the wind speed of the indoor fan of the indoor unit to be less than or equal to the first preset wind speed.

[0009] In some embodiments, the controller performing the control of the indoor fan in the indoor unit to have a wind speed less than or equal to the first preset wind speed is specifically configured to: calculate a ratio of a sum of capacities of the indoor units currently in the heating mode to a sum of capacities of the outdoor units currently in the heating mode; determine whether the ratio is greater than a determination value; if not, control the indoor fan of the indoor unit to have a wind speed less than or equal to the first preset wind speed; if yes, calculate a difference between the ratio and the determination value, calculate a product of the difference and the sum of the capacities of the outdoor units currently in the heating mode to obtain a shutdown capacity; and control the indoor fan of the indoor unit whose capacity is closest to the shutdown capacity to be turned off, and control the indoor fan of the remaining indoor units to have a wind speed less than or equal to the first preset wind speed.

[0010] In some embodiments, after the controller performing the control of the indoor fan in the indoor unit to have a wind speed less than or equal to the first preset wind speed, the controller is further configured to: determine whether the target outdoor unit satisfies a defrosting end condition; and if yes, release the control of the indoor fan.

[0011] In some embodiments, before the controller performing the control of the target outdoor unit to perform the bypass defrosting mode by using the defrosting branch, the controller is further configured to: control R first outdoor units in the shutdown mode to switch to the heating mode; R≥1, and R is an integer.

[0012] In some embodiments, the controller performing the control of the R first outdoor units in the shutdown mode to switch to the heating mode is specifically configured to: obtain a number M of the target outdoor units currently in the heating mode, and obtain a total number N of the outdoor units in the multi-split air conditioning system; M≥1, N≥M, and N and M are integers; wherein N-M≥R, N-M is a number of the first outdoor units in the shutdown mode in the multi-split air conditioning system; determine whether N / 2 satisfies a condition of being greater than or equal to M; if yes, control M first outdoor units to switch to the heating mode, and control M target outdoor units to switch to the defrosting mode; after the M target outdoor units satisfy a defrosting end condition, the M target outdoor units switch to the shutdown mode; if not, control T first outdoor units to switch to the heating mode, and control A target outdoor units to switch to the defrosting mode; T≥1, and T is an integer; when M is even, A is M / 2; when M is odd, and A takes the largest integer less than M / 2; after the A target outdoor units satisfy the defrosting end condition, control the A target outdoor units to switch to the heating mode, and control M-A target outdoor units to switch to the defrosting mode; after the M-A target outdoor units satisfy the defrosting end condition, control the M-A target outdoor units to switch to the heating mode, and control the T first outdoor units to switch to the shutdown mode.

[0013] In some embodiments, the controller performing the control of the T first outdoor units switching to the heating mode is specifically configured to: determine whether N-M is greater than M / 2; if yes, control A first outdoor units switching to the heating mode, where T=A; if no, control N-M first outdoor units switching to the heating mode, where T=N-M.

[0014] In some embodiments, after the controller performs the determination of whether N / 2 meets the condition of being greater than or equal to M, the controller is further configured to: determine whether M is 1; if yes, control the i th first outdoor unit switching to the heating mode, and control the target outdoor unit switching to the defrosting mode; where N-M≥i≥1, and i is an integer; after the target outdoor unit meets a defrosting end condition, control the target outdoor unit switching to a shutdown mode; after the i th first outdoor unit meets a defrosting condition, control the i th first outdoor unit switching to the defrosting mode, and control the i+1 th first outdoor unit switching to the heating mode.

[0015] In some embodiments, the controller performing the determination of whether the target outdoor unit meets the defrosting end condition is specifically configured to: acquire an outlet air temperature of the target outdoor unit; determine whether the outlet air temperature is greater than or equal to a third preset temperature; if yes, the target outdoor unit meets the defrosting end condition; if no, the target outdoor unit does not meet the defrosting end condition. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present disclosure, the following will briefly introduce the drawings needed to be used in some embodiments of the present disclosure. Obviously, the drawings in the following description are only the drawings of some embodiments of the present disclosure, and other drawings can also be obtained by those skilled in the art according to these drawings. In addition, the drawings in the following description can be regarded as schematic diagrams, and are not limited to the actual size of the products involved in the embodiments of the present disclosure.

[0017] Figure 1 a structure diagram of a multi-split air conditioning system in some embodiments of the present disclosure;

[0018] Figure 2 a structure diagram of another multi-split air conditioning system in some embodiments of the present disclosure;

[0019] Figure 3 a structure diagram of still another multi-split air conditioning system in some embodiments of the present disclosure;

[0020] Figure 4 a structure diagram of still another multi-split air conditioning system in some embodiments of the present disclosure;

[0021] Figure 5Structure diagram of a multi-split air conditioning system according to another embodiment of the present disclosure;

[0022] Figure 6 Execution step diagram of a controller of a multi-split air conditioning system according to another embodiment of the present disclosure;

[0023] Figure 7 Execution step diagram of a controller of a multi-split air conditioning system according to another embodiment of the present disclosure;

[0024] Figure 8 Execution step diagram of a controller of a multi-split air conditioning system according to another embodiment of the present disclosure;

[0025] Figure 9 Execution step diagram of a controller of a multi-split air conditioning system according to another embodiment of the present disclosure;

[0026] Figure 10 Execution step diagram of a controller of a multi-split air conditioning system according to another embodiment of the present disclosure;

[0027] Figure 11 Execution step diagram of a controller of a multi-split air conditioning system according to another embodiment of the present disclosure;

[0028] Figure 12 Execution step diagram of a controller of a multi-split air conditioning system according to embodiment one of the present disclosure;

[0029] Figure 13 Execution step diagram of a controller of a multi-split air conditioning system according to embodiment two of the present disclosure;

[0030] Figure 14 Execution step diagram of a controller of a multi-split air conditioning system according to embodiment three of the present disclosure;

[0031] Figure 15 Execution step diagram of a controller of a multi-split air conditioning system according to embodiment four of the present disclosure;

[0032] Figure 16 Execution step diagram of a controller of a multi-split air conditioning system according to embodiment five of the present disclosure;

[0033] Figure 17 Execution step diagram of a controller of a multi-split air conditioning system according to embodiment six of the present disclosure;

[0034] Figure 18 Execution step diagram of a controller of a multi-split air conditioning system according to embodiment seven of the present disclosure;

[0035] Figure 19 Execution step diagram of a controller of a multi-split air conditioning system according to embodiment eight of the present disclosure;

[0036] Figure 20 Flowchart for execution steps of a controller of a multi-split air conditioning system according to Embodiment Nine of the present disclosure. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present disclosure will be described clearly and completely below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative work are within the protection scope of the present disclosure.

[0038] Unless otherwise required by context, the term "comprises" in the specification and claims is to be construed as an open, inclusive meaning, i.e., "comprises, but is not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "an exemplary embodiment" or "such as" are intended to indicate a particular feature, structure, material, or characteristic that is included in at least one embodiment of the present disclosure. The illustrative representations of the above terms do not necessarily indicate the same embodiment or example. In addition, the specific features, structures, materials or characteristics described can be included in any suitable manner in any one or more embodiments or examples.

[0039] The terms "first", "second", etc. are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present disclosure, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0040] In the description of the present disclosure, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected", "communicated" should be understood broadly, for example, it can be fixed communication, or detachable communication, or integrally communicated; it can be mechanical communication, or electrical communication; it can be directly connected, or indirectly connected through an intermediate medium, or communication between two elements inside. For those of ordinary skill in the art, the specific meaning of the above terms in the present disclosure can be understood according to the specific circumstances.

[0041] The use of "configured to" herein means open and inclusive language that does not exclude devices that are adapted to perform additional tasks or steps.

[0042] In an implementation, in a continuous heating mode of the multi-split air conditioning system, the outdoor unit is prone to frosting, and when the outdoor unit enters a defrosting mode, the indoor heat exchanger is much lower than the indoor environment temperature, and the indoor fan does not blow air, which easily causes the indoor environment temperature to decrease, resulting in poor heating effect of the multi-split air conditioning system and poor thermal comfort experience of the user.

[0043] Based on this, as shown in the Figure 1 embodiments of the present disclosure provide a multi-split air conditioning system 1000, which includes a plurality of parallel-connected outdoor units 100 and a plurality of parallel-connected indoor units 200.

[0044] For example, the plurality of outdoor units 100 are connected, and the plurality of indoor units 200 are connected.

[0045] In some examples, as shown in the Figure 2 above, the outdoor unit 100 includes a compressor 11, a first reversing valve 12, a second reversing valve 13, an outdoor heat exchanger 14, a first stop valve 15, a second stop valve 16, an outdoor fan 17, a one-way valve 18, an oil separator 19, a capillary tube 20, a gas-liquid separator 21, and a first throttling valve 22.

[0046] In some examples, the indoor unit 200 includes an indoor heat exchanger 23, a second throttling valve 24, and an indoor fan 25.

[0047] For example, the plurality of outdoor units 100 are connected, and the plurality of indoor units 200 are connected.

[0048] For example, the plurality of outdoor units 100 are connected, and the plurality of indoor units 200 are connected.

[0049] For example, the plurality of outdoor units 100 are connected, and the plurality of indoor units 200 are connected.

[0050] For example, the plurality of outdoor units 100 are connected, and the plurality of indoor units 200 are connected.

[0051] For example, when the multi-split air conditioning system 1000 is in cooling mode, the high-temperature refrigerant discharged by the compressor 11 in the outdoor unit 100 flows sequentially through the one-way valve 18, the oil separator 19, the first valve port 131 and the second valve port 132 of the second reversing valve 13, the outdoor heat exchanger 14, the first throttle valve 22, the second shut-off valve 16, the second throttle valve 24, the indoor heat exchanger 23, the first shut-off valve 15, the second valve port 122 and the third valve port 123 of the first reversing valve 12, and the gas-liquid separator 21, before returning to the compressor 11.

[0052] In the multi-split air conditioning system described above, when the outdoor heat exchanger 14 of the outdoor unit is frosted, reverse defrosting can be used for defrosting. The defrosting mode follows the same refrigerant flow direction as the cooling mode described above. Reverse defrosting offers high efficiency and shortens defrosting time; however, during defrosting, the indoor unit does not heat, the indoor fan does not blow air, and the indoor ambient temperature drops, failing to meet heating requirements and resulting in a poor user experience.

[0053] Therefore, the outdoor unit of the multi-split air conditioning system provided in this disclosure also includes a defrost branch.

[0054] In some examples, such as Figure 3 As shown, the outdoor unit also includes a third throttle valve 26. The first end of the third throttle valve 26 is connected to the first end of the outdoor heat exchanger 14 via a connecting pipe 30, and the second end of the third throttle valve 26 is connected to the first end of the oil separator 19 via a connecting pipe. This third throttle valve 26 and the connecting pipes 30 connected to its two ends constitute the first defrost branch.

[0055] For example, when the multi-split air conditioning system 1000 is in defrost mode and defrosting is performed using the first defrost branch, the high-temperature refrigerant discharged by the compressor 11 in the outdoor unit 100 flows sequentially through the one-way valve 18, the oil separator 19, the third throttle valve 26, the outdoor heat exchanger 14, the second valve port 132 and the third valve port 133 of the second reversing valve 13, and the gas-liquid separator 21, and then returns to the compressor 11 to complete the defrosting of the outdoor heat exchanger 14.

[0056] In other examples, such as Figure 4 As shown, the outdoor unit also includes a fourth throttle valve 27. The first end of the fourth throttle valve 27 is connected to the first end of the outdoor heat exchanger 14 via a connecting pipe 30, and the second end of the fourth throttle valve 27 is connected to the first end of the gas-liquid separator 21 via a connecting pipe 30. This fourth throttle valve 27 and the connecting pipes 30 connected to its two ends constitute the second defrost branch.

[0057] Exemplarily, when the multi-split air conditioning system 1000 is in the defrosting mode and defrosting is performed by using the second defrosting branch, the high-temperature refrigerant discharged from the compressor 11 in the outdoor unit 100 flows through the one-way valve 18, the oil separator 19, the first valve port 131 and the second valve port 132 of the second reversing valve 13, the outdoor heat exchanger 14, the fourth throttling valve 27 and the gas-liquid separator 21 in sequence, and then returns to the compressor 11, thereby completing defrosting of the outdoor heat exchanger 14.

[0058] In yet some examples, as shown in Figure 5 the outdoor unit further comprises a fifth throttling valve 28, a sixth throttling valve 29 and an auxiliary heat exchanger 31. The first end A of the auxiliary heat exchanger 31 is in communication with the first stop valve 15, the second end B of the auxiliary heat exchanger 31 is in communication with the first end of the sixth throttling valve 29, the third end C of the auxiliary heat exchanger 31 is in communication with the first end of the fifth throttling valve 28, the fourth end D of the auxiliary heat exchanger 31 is in communication with the first end of the gas-liquid separator 21, the first end of the auxiliary heat exchanger 31 is in communication with the second end thereof inside the auxiliary heat exchanger 31, and the third end of the auxiliary heat exchanger 31 is in communication with the fourth end thereof inside the auxiliary heat exchanger 31. The second end of the fifth throttling valve 28 is in communication with the second end of the outdoor heat exchanger 14, and the second end of the sixth throttling valve 29 is in communication with the second stop valve 16. The auxiliary heat exchanger 31 and the on-line pipes 30 connected to the two ends thereof, the fifth throttling valve 28 and the on-line pipes 30 connected to the two ends thereof constitute a third defrosting branch.

[0059] Exemplarily, when the multi-split air conditioning system 1000 is in the defrosting mode and defrosting is performed by using the third defrosting branch, the high-temperature refrigerant discharged from the compressor 11 in the outdoor unit 100 flows through the one-way valve 18, the oil separator 19, the first valve port 131 and the second valve port 132 of the second reversing valve 13, enters the outdoor heat exchanger 14, and then enters the auxiliary heat exchanger 31 through the fifth throttling valve 28 to absorb heat, and then enters the compressor 11 through the gas-liquid separator 21, thereby completing defrosting of the outdoor heat exchanger 14.

[0060] It can be understood that the defrosting branches herein include the first defrosting branch, the second defrosting branch and the third defrosting branch.

[0061] In some embodiments, as shown in Figures 3-5 the multi-split air conditioning system further comprises a controller 300. The controller 300 is electrically connected to the outdoor unit 100 and the indoor unit 200. Figures 3-5 In some embodiments, as shown in

[0062] The controller 300 can control the outdoor unit 100 and the indoor unit 200 to enter corresponding working modes, such as a heating mode, a defrosting mode, etc.

[0063] In some examples, as shown in Figure 6As shown, the controller 300 is configured to:

[0064] S100, determine whether the outdoor unit in the heating mode meets the defrosting condition; set the outdoor unit meeting the defrosting condition as the target outdoor unit.

[0065] For example, since the multi-split air conditioning system in the present disclosure includes multiple parallel connected outdoor units, after determining whether the multiple outdoor units meet the defrosting condition, the outdoor unit meeting the defrosting condition can be at least one, that is, there can be multiple outdoor units meeting the defrosting condition.

[0066] In some examples, the defrosting condition can have multiple types, such as frost thickness, etc., and the present disclosure does not limit this.

[0067] For example, the defrosting condition can be that the outdoor unit currently in the heating mode is obtained, and it is determined whether the air outlet temperature is less than the defrosting temperature. If the air outlet temperature is less than the defrosting temperature, it is considered that the outdoor unit meets the defrosting condition, and the outdoor unit is the target outdoor unit. Otherwise, it can be considered that the outdoor unit does not meet the defrosting condition.

[0068] S200, determine whether the outlet temperature of the outdoor heat exchanger in the target outdoor unit is greater than or equal to a first preset temperature.

[0069] For example, the outlet temperature of the outdoor heat exchanger refers to the temperature of the pipeline through which the refrigerant flows out of the outdoor heat exchanger in the heating mode. Specifically, in the embodiment, the outlet temperature of the outdoor heat exchanger refers to the temperature of the pipeline between the outdoor heat exchanger 14 and the second reversing valve 13. Figures 3-5

[0070] For example, in the multi-split air conditioning system provided in the above embodiment of the present disclosure, the multi-split air conditioning system further includes a first temperature sensor located between the outdoor heat exchanger 14 and the second reversing valve 13, for detecting the outlet temperature of the outdoor heat exchanger 14.

[0071] Therefore, the frosting condition of the outdoor heat exchanger can be roughly determined, thereby providing a basis for the selection of the defrosting mode.

[0072] S300a, if not, control the target outdoor unit to perform the reverse defrosting mode; control the indoor fan of the indoor unit to not work; and control the defrosting branch to block the compressor 11 and the outdoor heat exchanger 14.

[0073] For example, the outlet temperature detected by the first temperature sensor is -15℃, and the first preset temperature can be -10℃. At this time, the outlet temperature is less than the first preset temperature, and the reverse defrosting mode is used for defrosting operation.

[0074] ​Understandably, reverse defrosting has higher defrosting efficiency. When the outdoor heat exchanger is severely frosted, reverse defrosting can be used to quickly complete the defrosting operation, thus saving defrosting time.

[0075] When the target outdoor unit enters reverse defrosting mode, the indoor fan of the control indoor unit does not work, and the indoor fan speed is 0. This can prevent the indoor fan outlet temperature from being too low and thus exacerbating the drop in indoor ambient temperature, thereby avoiding a reduction in the heating effect of the multi-split air conditioning system.

[0076] For example, in Figure 3 In the multi-split air conditioning system shown, the controller closes the third throttle valve 26, thereby blocking the defrost branch from the passage between the compressor 11 and the outdoor heat exchanger 14. For example, in Figure 4 In the multi-split air conditioning system shown, the controller closes the fourth throttle valve 27, thereby blocking the defrost branch from the passage between the compressor 11 and the outdoor heat exchanger 14. For example, in Figure 3 In the multi-split air conditioning system shown, the controller controls the fifth throttle valve 28 to close, thereby blocking the passage between the compressor 11 and the outdoor heat exchanger 14 in the defrost branch.

[0077] S300b, if yes, then control the target outdoor unit to perform bypass defrosting using the defrosting branch; control the indoor fan speed in the indoor unit to be less than or equal to the first preset speed; control the defrosting branch to connect the compressor and the outdoor heat exchanger, so that part of the refrigerant enters the outdoor heat exchanger from the compressor's exhaust port through the defrosting branch, or, the refrigerant enters the outdoor heat exchanger from the compressor's exhaust port, and part of the refrigerant discharged from the outdoor heat exchanger enters the compressor's suction port through the defrosting branch, thereby defrosting the outdoor heat exchanger.

[0078] For example, if the outlet temperature detected by the first temperature sensor is -8℃, the first preset temperature can be -10℃. In this case, the outlet temperature is greater than the first preset temperature, and a bypass defrosting method is used for defrosting.

[0079] For example, the first preset wind speed is less than the wind speed of the indoor fan when the multi-split air conditioning system normally enters the heating mode, and the first preset wind speed is greater than or equal to 0.

[0080] For example, the airflow speed of the indoor fan in the indoor unit is lower than the originally set speed, such as a gentle breeze.

[0081] For example, in the case of defrosting operation using bypass defrosting, Figure 3The multi-connected air conditioning system is taken as an example. The controller controls the first defrost branch to be communicated with the compressor and the outdoor heat exchanger, so that part of the refrigerant discharged by the compressor enters the outdoor heat exchanger through the first defrost branch, thereby defrosting the outdoor heat exchanger of the target outdoor unit. At the same time, the controller also controls another part of the high-temperature refrigerant discharged by the compressor of the target outdoor unit to enter the indoor heat exchanger through the one-way valve, the first reversing valve and the first stop valve in sequence, and releases heat in the indoor heat exchanger, so that the outlet air temperature of the indoor heat exchanger is relatively high, and the temperature of the air blown by the indoor fan is relatively high, thereby maintaining the outlet air temperature of the indoor unit to be relatively high while defrosting the target outdoor unit, so that the multi-connected air conditioning system can continuously heat while defrosting, improve the heating efficiency of the multi-connected air conditioning system, and provide a better experience for the user.

[0082] For example, in the case of defrosting operation by using the bypass defrosting mode, the controller controls the first defrost branch to be communicated with the compressor and the outdoor heat exchanger, so that part of the refrigerant discharged by the compressor enters the outdoor heat exchanger through the first defrost branch, thereby defrosting the outdoor heat exchanger of the target outdoor unit. At the same time, the controller also controls another part of the high-temperature refrigerant discharged by the compressor of the target outdoor unit to enter the indoor heat exchanger through the one-way valve, the first reversing valve and the first stop valve in sequence, and releases heat in the indoor heat exchanger, so that the outlet air temperature of the indoor heat exchanger is relatively high, and the temperature of the air blown by the indoor fan is relatively high, thereby maintaining the outlet air temperature of the indoor unit to be relatively high while defrosting the target outdoor unit, so that the multi-connected air conditioning system can continuously heat while defrosting, improve the heating efficiency of the multi-connected air conditioning system, and provide a better experience for the user. Figure 4 The multi-connected air conditioning system is taken as an example. The controller controls the first defrost branch to be communicated with the compressor and the outdoor heat exchanger, so that part of the refrigerant discharged by the compressor enters the outdoor heat exchanger through the first defrost branch, thereby defrosting the outdoor heat exchanger of the target outdoor unit. At the same time, the controller also controls another part of the high-temperature refrigerant discharged by the compressor of the target outdoor unit to enter the indoor heat exchanger through the one-way valve, the first reversing valve and the first stop valve in sequence, and releases heat in the indoor heat exchanger, so that the outlet air temperature of the indoor heat exchanger is relatively high, and the temperature of the air blown by the indoor fan is relatively high, thereby maintaining the outlet air temperature of the indoor unit to be relatively high while defrosting the target outdoor unit, so that the multi-connected air conditioning system can continuously heat while defrosting, improve the heating efficiency of the multi-connected air conditioning system, and provide a better experience for the user.

[0083] For example, in the case of defrosting operation by using the bypass defrosting mode, the controller controls the first defrost branch to be communicated with the compressor and the outdoor heat exchanger, so that part of the refrigerant discharged by the compressor enters the outdoor heat exchanger through the first defrost branch, thereby defrosting the outdoor heat exchanger of the target outdoor unit. At the same time, the controller also controls another part of the high-temperature refrigerant discharged by the compressor of the target outdoor unit to enter the indoor heat exchanger through the one-way valve, the first reversing valve and the first stop valve in sequence, and releases heat in the indoor heat exchanger, so that the outlet air temperature of the indoor heat exchanger is relatively high, and the temperature of the air blown by the indoor fan is relatively high, thereby maintaining the outlet air temperature of the indoor unit to be relatively high while defrosting the target outdoor unit, so that the multi-connected air conditioning system can continuously heat while defrosting, improve the heating efficiency of the multi-connected air conditioning system, and provide a better experience for the user. Figure 5The multi-connected air conditioning system shown is taken as an example. After the controller controls the third defrost branch to be connected to the compressor and the room temperature heat exchanger, the controller controls the refrigerant to enter the outdoor heat exchanger from the exhaust port of the compressor, and part of the refrigerant discharged from the outdoor heat exchanger enters the suction port of the compressor through the third defrost branch, so as to defrost the outdoor heat exchanger. At the same time, the controller also controls part of the refrigerant discharged from the outdoor unit in parallel with the target outdoor unit and in the heating mode to enter the auxiliary heat exchanger through the first reversing valve, the first stop valve and the first stop valve of the target outdoor unit, and the sixth throttling valve 29, the second stop valve of the target outdoor unit flows out of the target outdoor unit, so that the outdoor unit in the heating mode assists the target outdoor unit in defrosting, thereby improving the defrosting efficiency. The refrigerant flowing out of the target outdoor unit is combined with the refrigerant flowing out of the indoor unit in the on-line pipe, and then flows into the outdoor heat exchanger of the outdoor unit in parallel with the target outdoor unit and in the heating mode through the second stop valve. Another part of the high-temperature refrigerant discharged from the outdoor unit in the heating mode enters the indoor unit through the first reversing valve and the first stop valve, and exchanges heat with the indoor heat exchanger, so that the outlet air temperature of the indoor unit is high, thereby enabling the multi-connected air conditioning system to continuously heat while defrosting, improving the heating efficiency of the multi-connected air conditioning system, and providing a better user experience.

[0084] The multi-connected air conditioning system provided by some embodiments of the present disclosure detects and judges the outlet air temperature of the outdoor heat exchanger that meets the defrosting condition through the controller. For the target outdoor unit with an outlet temperature less than a first preset temperature, the controller controls the target outdoor unit to perform reverse defrosting to defrost, and controls the indoor fan of the indoor unit to be inoperative. For the target outdoor unit with an outlet temperature greater than or equal to the first preset temperature, the controller controls the defrost branch to perform bypass defrosting, controls the passage between the compressor and the outdoor heat exchanger of the defrost branch, and controls the indoor fan of the indoor unit to blow air with a speed less than the first preset air speed. Thus, different defrosting modes and control modes of the indoor fan are adopted according to different frosting conditions, which can improve the heating efficiency of the multi-connected air conditioning system, provide a better heating comfort for the user, and avoid the situation that the outlet air temperature of the indoor unit is low when the target outdoor unit defrosts, thereby affecting the heating effect of the multi-connected air conditioning system. In addition, the target outdoor unit can be defrosted separately without affecting the heating process of the outdoor unit connected in parallel therewith during the defrosting process by using the defrost branch, thereby realizing uninterrupted and continuous heating effect of the multi-connected air conditioning system and avoiding the influence of the defrosting process on the heating effect.

[0085] It can be understood that, during the process in which the controller controls the speed of the indoor fan in the indoor unit to be less than or equal to the first preset air speed, the specific configuration mode of the controller can be various, and can be selected and set according to actual needs.

[0086] In some embodiments, as Figure 7As shown in S300b, when the wind speed of the indoor fan in the indoor unit is less than or equal to the first preset wind speed, the controller is specifically configured to:

[0087] S310b, obtain the exhaust pressure of the target outdoor unit.

[0088] S320b, determine whether the exhaust pressure is greater than or equal to the preset pressure.

[0089] S321c, if not, control the indoor fan to not blow air.

[0090] S322c, determine whether the target outdoor unit satisfies the defrosting end condition; if yes, release the control of the indoor fan.

[0091] S321d, if yes, obtain the outlet air temperature of the indoor unit every first preset time; the number of indoor units is P, P≥1, and P is an integer;

[0092] S322d, determine whether the outlet air temperature of the indoor unit is greater than or equal to the second preset temperature;

[0093] S3221e, if not, calculate the number of indoor units with outlet air temperature less than the second preset temperature;

[0094] S3222e, if the number of indoor units with outlet air temperature less than the second preset temperature is 1, turn off the indoor fan of the indoor unit;

[0095] S3223e, if the number of indoor units with outlet air temperature less than the second preset temperature is greater than 1, sort the capacities of the multiple indoor units, and turn off the indoor fan of the indoor unit with the smallest capacity;

[0096] S3221f, if yes, control the wind speed of the indoor fan of the indoor unit to be less than or equal to the first preset wind speed.

[0097] Exemplarily, the preset pressure can be 2.0 Mpa.

[0098] Exemplarily, the release of the control of the indoor fan means that the indoor fan operates at the wind speed set by the user and is not controlled by the controller.

[0099] Exemplarily, the first preset time can be 10s, and the second preset temperature can be 10℃, for example, the outlet air temperature of the indoor unit is obtained every 10s to determine whether the temperature is greater than or equal to 10℃.

[0100] With the above setting mode, when defrosting is performed by using the defrost branch in the heating process of the multi-split air conditioning system, the air outlet of the indoor unit is maintained and the air outlet temperature is relatively high, the air outlet temperature of the indoor fan can be accurately controlled, the air speed of the indoor fan is adjusted according to different situations, the user experience is improved, and when some outdoor units of the multi-split air conditioning system are defrosting in the heating mode, the air outlet temperature of the indoor unit is relatively low, which affects the heating demand of the user.

[0101] In some embodiments, as shown in FIG. 3b, when the controller controls the air speed of the indoor fan in the indoor unit to be less than or equal to the first preset air speed in S300b, the controller is specifically configured to: Figure 8

[0102] S330b, calculating the ratio of the sum of the capacities of the indoor units currently in the heating mode to the sum of the capacities of the outdoor units currently in the heating mode;

[0103] S340b, judging whether the ratio is greater than a determination value;

[0104] S341c, if not, controlling the air speed of the indoor fan of the indoor unit to be less than or equal to the first preset air speed;

[0105] S341d, if yes, calculating the difference between the ratio and the determination value, and calculating the product of the difference and the sum of the capacities of the outdoor units currently in the heating mode to obtain a closing capacity;

[0106] S342d, according to the closing capacity, controlling the indoor fan of the indoor unit with the capacity closest to the closing capacity to be closed, and controlling the air speed of the indoor fan of the remaining indoor units to be less than or equal to the first preset air speed.

[0107] For example, the ratio can be 90%, the determination value can be 75%, the ratio is greater than the determination value, the difference between the ratio and the determination value is 15%, and the closing capacity is obtained according to the product of 15% and the sum of the capacities of the outdoor units. The capacities of the indoor units in the heating mode are sorted from small to large to obtain the indoor unit with the capacity closest to the closing capacity, and the indoor fan of the indoor unit is controlled to be closed, while the indoor fans of the remaining indoor units are controlled to blow a slight breeze.

[0108] With the above setting mode, when defrosting is performed by using the defrost branch in the heating process of the multi-split air conditioning system, the air outlet of the indoor unit is maintained and the air outlet temperature is relatively high, thereby improving the user experience and avoiding the air outlet speed of the indoor fan being too large to cause the indoor air and the indoor heat exchanger to fully exchange heat, thereby reducing the indoor temperature and affecting the user experience.

[0109] ​In some embodiments, after the controller executes the control of the indoor fan in the indoor unit to have the wind speed less than or equal to the first preset wind speed in S300b, the controller is further configured to: S400b, determine whether the target outdoor unit satisfies a defrosting end condition; and if yes, release the control of the indoor fan. In this way, the control of the indoor fan can be released in time, so as to avoid the indoor fan from not blowing wind for a long time and reducing the user experience.

[0110] In some embodiments, as shown in S400b, when the controller executes the control of the indoor fan in the indoor unit to have the wind speed less than or equal to the first preset wind speed in S400b, the controller is specifically configured to: Figure 9

[0111] S410b, acquire the outlet air temperature of the target outdoor unit;

[0112] S420b, determine whether the outlet air temperature is greater than or equal to a third preset temperature; if yes, the target outdoor unit satisfies the defrosting end condition; and if no, the target outdoor unit does not satisfy the defrosting end condition.

[0113] For example, the third preset temperature can be 5℃.

[0114] For example, a temperature sensor can be used to test the outlet air temperature of the outdoor unit of the panel.

[0115] In this way, the defrosting condition of the target outdoor unit can be accurately obtained, so as to facilitate the target outdoor unit to switch to the heating mode in time, thereby improving the heating efficiency of the multi-split air conditioning system.

[0116] In some embodiments, before the controller executes S300b to control the target outdoor unit to perform the bypass defrosting mode by using the defrosting branch, the controller is further configured to:

[0117] S210b, control R first outdoor units in a shutdown mode to switch to a heating mode; R≥1, and R is an integer.

[0118] The first outdoor unit refers to an outdoor unit that is not currently working.

[0119] For example, the value of R is less than or equal to the number of target outdoor units that satisfy the defrosting condition. After the R first outdoor units in the shutdown mode are switched to the heating mode, the target outdoor unit can enter the defrosting mode. In this way, the indoor unit can continuously blow hot air, so as to realize uninterrupted heating of the multi-split air conditioning system and improve the user experience.

[0120] In some embodiments, as shown in S400b, when the controller executes the control of the indoor fan in the indoor unit to have the wind speed less than or equal to the first preset wind speed in S400b, the controller is specifically configured to: Figure 10 ​As shown, in the above S210b, the controller performs control on the R first outdoor units in the shutdown mode to switch to the heating mode, and the controller is specifically configured to: S211b, acquire the number M of target outdoor units currently in the heating mode, and acquire the total number N of outdoor units in the multi-split air conditioning system; M≥1, N≥M, and N and M are integers; wherein N-M≥R, and N-M is the number of the first outdoor units in the shutdown mode in the multi-split air conditioning system;

[0121] S212b, determine whether N / 2 satisfies greater than or equal to M;

[0122] S2121c, if yes, control the M first outdoor units to switch to the heating mode, and control the M target outdoor units to switch to the defrosting mode; after the M target outdoor units satisfy the defrosting end condition, the M target outdoor units switch to the shutdown mode;

[0123] S2121d, if no, control the T first outdoor units to switch to the heating mode, and control the A target outdoor units to switch to the defrosting mode; T≥1, and T is an integer; when M is even, A is M / 2, and when M is odd, A takes the smallest integer greater than M / 2;

[0124] S2122d, after the A target outdoor units satisfy the defrosting end condition, control the A target outdoor units to switch to the heating mode, and control the M-A target outdoor units to switch to the defrosting mode;

[0125] S2123d, after the M-A target outdoor units satisfy the defrosting end condition, control the M-A target outdoor units to switch to the heating mode,

[0126] S2124d, control the T first outdoor units to switch to the shutdown mode.

[0127] For example, when M takes 4, A takes 2, and when M takes 5, A takes 3.

[0128] By using the above setting mode, the multiple outdoor units in the multi-split air conditioning system can be alternately heated, so that the target outdoor units can complete the defrosting operation without affecting the overall heating efficiency of the multi-split air conditioning system, and the user experience is greatly improved. Since the bypass defrosting mode is adopted in the embodiments of the present disclosure, the connection pipe connected with the indoor unit can maintain a relatively high temperature, and when the heating is started again after the defrosting is completed, the heating efficiency of the outdoor unit can be relatively high, uninterrupted heating is realized, and the user experience is effectively improved. In addition, the multiple outdoor units alternately heat, which can also improve the long-term operation reliability of the compressor and avoid damage to the compressor due to long operation time of a single outdoor unit.

[0129] In some embodiments, as Figure 11As shown in the above S2124d, the controller performs control T first outdoor units to switch to the heating mode, and the controller is specifically configured to:

[0130] S2125d, judge whether N-M is greater than M / 2;

[0131] If yes, control A first outdoor units to switch to the heating mode, wherein T=A;

[0132] If no, control N-M first outdoor units to switch to the heating mode, wherein T=N-M.

[0133] With the above setting mode, a certain number of first outdoor units in the shutdown state can be switched to the heating state, so that a certain number of target outdoor units to be defrosted are defrosted, and after the defrosting of the certain number of target outdoor units to be defrosted is completed, the remaining number of target outdoor units to be defrosted are controlled to defrost, so that all target outdoor units to be defrosted complete defrosting, and during the defrosting process, the original number of outdoor units are maintained to heat, so that the indoor unit can continuously provide hot air, so that the multi-split air conditioning system can realize true continuous heating, greatly improving the user experience.

[0134] In some embodiments, after the controller judges whether N / 2 is greater than or equal to M in the above S212b, the controller is further configured to:

[0135] Judge whether M is 1;

[0136] If yes, control the i-th first outdoor unit to switch to the heating mode, and control the target outdoor unit to switch to the defrosting mode; wherein N-M≥i≥1, and i is an integer;

[0137] After the target outdoor unit meets the defrosting end condition, control the target outdoor unit to switch to the shutdown mode;

[0138] After the i-th first outdoor unit meets the defrosting condition, control the i-th first outdoor unit to switch to the defrosting mode, and control the i+1-th first outdoor unit to switch to the heating mode.

[0139] For example, when only one target outdoor unit needs to be defrosted, the first first outdoor unit in the plurality of first outdoor units is used for heating, and the target outdoor unit is defrosted. When the target outdoor unit ends defrosting, it is switched to the shutdown state. After the first first outdoor unit meets the defrosting condition, the first first outdoor unit defrosts, and the second first outdoor unit is switched from the shutdown state to the heating mode. In this way, the plurality of outdoor units in the entire multi-split air conditioning system are cycled to heat.

[0140] With the above setting mode, the original number of outdoor units can be maintained to perform heating during the defrosting process, so that the indoor unit can continuously provide hot air, and the multi-split air conditioning system can realize true continuous heating, greatly improving the user experience. In addition, the rotation of multiple outdoor units for heating can also improve the long-term operation reliability of the compressor and avoid damage to the compressor due to long operation time of a single outdoor unit.

[0141] Next, the defrosting mode of different multi-split air conditioning systems will be introduced in combination with the multi-split air conditioning system provided by some embodiments of the present disclosure.

[0142] In embodiment one, the controller identifies that the multi-split air conditioning system includes two parallel outdoor units, and only one outdoor unit is currently operating in heating mode and meets the defrosting condition, which is the target outdoor unit. The one outdoor unit is in the stop mode, which is the first outdoor unit.

[0143] As shown in Figure 12 , first, the controller determines that the outlet temperature of the outdoor heat exchanger in the target outdoor unit is greater than the first preset temperature, so the target outdoor unit can perform bypass defrosting. For convenience of description, the target outdoor unit in this embodiment can be target outdoor unit A, and the first outdoor unit can be first outdoor unit B. Then, the controller controls the first outdoor unit B to switch from the stop mode to the heating mode, and the target outdoor unit A to switch to the defrosting mode. Specifically, the high-temperature refrigerant of the target outdoor unit A flows into the outdoor heat exchanger of the target outdoor unit for defrosting by bypassing the flow path, and the high-temperature refrigerant of the first outdoor unit B flows into the indoor unit for providing high-temperature heat source for the indoor by the compressor, the one-way valve, the oil separator, the first four-way valve, and the first stop valve. When the target outdoor unit A meets the defrosting exit condition, the target outdoor unit A ends the hot gas bypass defrosting and switches from the defrosting mode to the stop mode; the first outdoor unit B maintains the heating mode to continuously provide heat for the indoor side, realizing the function of uninterrupted heating of the indoor unit.

[0144] Thus, in the scenario of two outdoor units in combination and single outdoor unit operation, different outdoor units rotate to operate, which can avoid the phenomenon of only one compressor working continuously, improving the service life and reliability of the compressor.

[0145] In embodiment two, the controller identifies that the multi-split air conditioning system includes two parallel outdoor units, and both of the two outdoor units are currently operating in heating mode and meet the defrosting condition, which are the target outdoor units. For convenience of description, the two target outdoor units in this embodiment can be target outdoor unit A and target outdoor unit B.

[0146] As shown in Figure 13As shown, first, the controller determines that the outlet temperature of the outdoor heat exchanger of the two target outdoor units is greater than the first preset temperature, and thus the two target outdoor units can perform the bypass defrosting mode. Then, the controller controls the target outdoor unit A to switch to the defrosting mode, the compressor of the target outdoor unit A continues to operate, and the throttling valve of the defrosting branch is opened to perform bypass defrosting. The target outdoor unit B still provides high-temperature refrigerant for the indoor unit to maintain a high outlet air temperature of the indoor unit; when the target outdoor unit A meets the defrosting end condition, the controller controls the target outdoor unit A to switch from the defrosting mode to the heating mode, and the target outdoor unit B switches from the heating mode to the defrosting mode, at which time the target outdoor unit A continuously provides high-temperature refrigerant for the indoor unit to maintain the outlet air temperature of the indoor unit; when the target outdoor unit B meets the defrosting exit condition, the target outdoor unit A and the target outdoor unit B both operate in the heating mode, and thus the rotation defrosting process of the two outdoor unit groups is completed. In this way, the outlet air temperature of the indoor unit can be maintained, and thus the heating efficiency of the multi-split air conditioning system is improved.

[0147] In example three, the controller identifies that the multi-split air conditioning system includes three parallel outdoor units, and only one outdoor unit is currently operating in the heating mode and meets the defrosting condition, and the one outdoor unit is the target outdoor unit, and the other two outdoor units are in the shutdown mode, and the two outdoor units are the first outdoor units.

[0148] As shown in FIG. 6, the controller controls the target outdoor unit A to switch from the heating mode to the defrosting mode, and the target outdoor unit B to switch from the shutdown mode to the heating mode. Figure 14As shown, first, it is judged that the outlet temperature of the outdoor heat exchanger in the target outdoor unit is greater than the first preset temperature, and therefore the target outdoor unit can perform the bypass defrosting mode. For the convenience of description, the target outdoor unit in this embodiment can be the target outdoor unit A, and the two first outdoor units can be the first outdoor unit A and the first outdoor unit B respectively. Then, the controller controls the first outdoor unit B to switch from the stop mode to the heating mode, and the target outdoor unit A to switch to the defrosting mode, and the throttle valve of the defrosting branch of the target outdoor unit A to open, to perform bypass defrosting. At this time, the first outdoor unit B provides high-temperature refrigerant for the indoor unit, so that the indoor unit does not interrupt heating; after the target outdoor unit A meets the defrosting end condition, the controller controls the target outdoor unit A to switch from the defrosting mode to the stop mode, and the first outdoor unit B to maintain the heating mode; the controller controls to monitor the running state of the first outdoor unit B in real time and judge whether the defrosting condition is met, and when the first outdoor unit B meets the condition, the controller controls the first outdoor unit C to switch from the stop mode to the heating mode, and then the first outdoor unit B to switch to the defrosting mode, until the first outdoor unit B meets the defrosting end condition, and after the first outdoor unit B switches from the defrosting mode to the stop mode, the first outdoor unit C maintains the heating mode, and judges whether the defrosting condition is met, and when the first outdoor unit C meets the condition, the target outdoor unit A switches from the stop mode to the heating mode, and then the first outdoor unit C switches to the defrosting mode, until the first outdoor unit C meets the defrosting end condition, and after the first outdoor unit C switches from the defrosting mode to the stop mode, the target outdoor unit A maintains the heating mode. In this way, the defrosting operation is completed.

[0149] In this way, the outlet air temperature of the indoor unit can be maintained, thereby improving the heating efficiency of the multi-split air conditioning system.

[0150] In the fourth embodiment, the controller identifies that the multi-split air conditioning system includes three parallel-connected outdoor units, and currently two outdoor units are running in the heating mode and meet the defrosting condition, which are the target outdoor units, and one outdoor unit is in the stop mode, which is the first outdoor unit.

[0151] As shown in FIG. 1, the multi-split air conditioning system includes three parallel-connected outdoor units, and the controller controls the three outdoor units to run in the heating mode. Figure 15As shown, first, the controller determines that the outlet temperature of the outdoor heat exchanger in the target outdoor unit is greater than the first preset temperature, and thus the target outdoor unit can perform bypass defrosting. For ease of description, the two target outdoor units in this embodiment can be target outdoor unit A and target outdoor unit B, and the one first outdoor unit can be first outdoor unit C. Then, the controller controls target outdoor unit A to switch from the heating mode to the defrosting mode, the compressor of target outdoor unit A continues to operate, and the throttle valve of the defrosting branch of target outdoor unit A is opened to perform bypass defrosting. The controller controls target outdoor unit B to remain in the heating mode, and the first outdoor unit C in the stop mode is started to switch from the stop mode to the heating mode. Target outdoor unit B and first outdoor unit C provide high-temperature refrigerant for the indoor unit to maintain a high outlet air temperature of the indoor unit. When target outdoor unit A in the defrosting mode satisfies the end-of-defrosting condition, the controller controls target outdoor unit A to switch from the defrosting mode to the heating mode, target outdoor unit B switches from the heating mode to the defrosting mode, and first outdoor unit C remains in the heating mode. When target outdoor unit B in the defrosting mode satisfies the end-of-defrosting condition, the controller controls target outdoor unit B to switch from the defrosting mode to the heating mode, and first outdoor unit C switches from the heating mode to the stop mode. The entire rotation defrosting process is completed.

[0152] Thus, the outlet air temperature of the indoor unit can be maintained, and the heating efficiency of the multi-split air conditioning system is improved.

[0153] In example five, the controller identifies that the multi-split air conditioning system includes three parallel-connected outdoor units, and that three outdoor units are currently operating in the heating mode and satisfy the defrosting condition, and the outdoor unit is the target outdoor unit.

[0154] As shown, first, the controller determines that the outlet temperature of the outdoor heat exchanger in the target outdoor unit is greater than the first preset temperature, and thus the target outdoor unit can perform bypass defrosting. For ease of description, the two target outdoor units in this embodiment can be target outdoor unit A and target outdoor unit B, and the one first outdoor unit can be first outdoor unit C. Then, the controller controls target outdoor unit A to switch from the heating mode to the defrosting mode, the compressor of target outdoor unit A continues to operate, and the throttle valve of the defrosting branch of target outdoor unit A is opened to perform bypass defrosting. The controller controls target outdoor unit B to remain in the heating mode, and the first outdoor unit C in the stop mode is started to switch from the stop mode to the heating mode. Target outdoor unit B and first outdoor unit C provide high-temperature refrigerant for the indoor unit to maintain a high outlet air temperature of the indoor unit. When target outdoor unit A in the defrosting mode satisfies the end-of-defrosting condition, the controller controls target outdoor unit A to switch from the defrosting mode to the heating mode, target outdoor unit B switches from the heating mode to the defrosting mode, and first outdoor unit C remains in the heating mode. When target outdoor unit B in the defrosting mode satisfies the end-of-defrosting condition, the controller controls target outdoor unit B to switch from the defrosting mode to the heating mode, and first outdoor unit C switches from the heating mode to the stop mode. The entire rotation defrosting process is completed. Figure 16 Thus, the outlet air temperature of the indoor unit can be maintained, and the heating efficiency of the multi-split air conditioning system is improved.

[0155] In the embodiment six, the controller identifies that the multi-connected air conditioning system includes four outdoor units in parallel, and currently two outdoor units are running in the heating mode and the outdoor units meeting the defrosting condition are target outdoor units, and the other two outdoor units are first outdoor units.

[0156] As shown in the embodiment one, first, the controller judges that the outlet temperature of the outdoor heat exchanger in the target outdoor unit is greater than the first preset temperature, and thus the target outdoor unit can execute the bypass defrosting mode. Figure 17 As shown in the embodiment one, first, the controller judges that the outlet temperature of the outdoor heat exchanger in the target outdoor unit is greater than the first preset temperature, and thus the target outdoor unit can execute the bypass defrosting mode.

[0157] In the embodiment seven, the controller identifies that the multi-connected air conditioning system includes four outdoor units in parallel, and currently two outdoor units are running in the heating mode and the outdoor units meeting the defrosting condition are target outdoor units, and the other two outdoor units are first outdoor units.

[0158] As shown in the embodiment one, first, the controller judges that the outlet temperature of the outdoor heat exchanger in the target outdoor unit is greater than the first preset temperature, and thus the target outdoor unit can execute the bypass defrosting mode. Figure 18 As shown in the embodiment one, first, the controller judges that the outlet temperature of the outdoor heat exchanger in the target outdoor unit is greater than the first preset temperature, and thus the target outdoor unit can execute the bypass defrosting mode.

[0159] Embodiment eight, the controller identifies that the multi-connected air conditioning system includes four outdoor units in parallel, and currently three outdoor units are running in heating mode and the outdoor units meet the defrosting condition, i.e., all are target outdoor units, and the remaining one outdoor unit is in the shutdown mode, which is the first outdoor unit.

[0160] As shown in Figure 19 , first, the controller determines that the outlet temperature of the outdoor heat exchanger in the target outdoor unit is greater than the first preset temperature, so the target outdoor unit can execute the bypass defrosting mode. For convenience of description, the three target outdoor units in this embodiment can be target outdoor unit A, target outdoor unit B, and target outdoor unit C, and the first outdoor unit is first outdoor unit D. Then, the controller controls the target outdoor unit A to switch from heating operation to defrosting mode in the bypass defrosting mode first, at this time, the target outdoor unit B, the target outdoor unit C, and the first outdoor unit D are all in the heating mode. When the target outdoor unit A meets the end defrosting condition, it switches from the defrosting mode to the heating mode, the target outdoor unit B and the target outdoor unit C are switched to the defrosting mode at the same time, when they meet the end defrosting condition, the corresponding target outdoor unit is switched from the defrosting mode to the heating mode, and when all target outdoor units are switched to the heating mode, since the first outdoor unit D is in the shutdown state before the target outdoor unit A defrosts, the first outdoor unit D is switched from the heating mode to the shutdown mode. At this time, the rotation defrosting control of uninterrupted heating ends, and the outdoor units in the heating mode are consistent with those before defrosting, which does not affect the reliable operation of the heating mode of the multi-connected air conditioning system.

[0161] Embodiment nine, the controller identifies that the multi-connected air conditioning system includes four outdoor units in parallel, and currently four outdoor units are running in heating mode and the outdoor units meet the defrosting condition, i.e., all are target outdoor units.

[0162] As shown in Figure 20As shown, first, the controller judges that the outlet temperature of the outdoor heat exchanger in the target outdoor unit is greater than the first preset temperature, and thus the target outdoor unit can perform the bypass defrosting mode. For the convenience of description, the four target outdoor units in this embodiment can be target outdoor unit A, target outdoor unit B, target outdoor unit C, and target outdoor unit D. Then, first, the controller controls the two outdoor units at the top of the heating order to perform the defrosting operation, that is, target outdoor unit A and target outdoor unit B are bypass defrosted, and target outdoor unit C and target outdoor unit D maintain heating to provide high-temperature refrigerant for the indoor heat exchanger. When it is judged that target outdoor unit A or target outdoor unit B meets the end defrosting condition, the defrosting mode is switched to the heating mode in turn, and when target outdoor unit A and target outdoor unit B are both switched to the heating mode, target outdoor unit C and target outdoor unit D that are not defrosted rotate into the bypass defrosting defrosting mode; when it is judged that target outdoor unit C and target outdoor unit D meet the end defrosting condition, the bypass defrosting defrosting mode is switched to the heating mode, at this time, target outdoor unit A, target outdoor unit B, target outdoor unit C, and target outdoor unit D all operate in the heating mode, and thus the uninterrupted heating rotation defrosting control is completed.

[0163] Therefore, the multi-split air conditioning system can continuously heat, and the user experience is improved.

[0164] Through the description of the above embodiments, those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above functional modules is exemplified, and in actual application, the above functions can be completed by different functional modules according to needs, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above.

[0165] The above is only a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto, and any change or replacement within the technical scope disclosed in the present disclosure should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims. In the description of the present disclosure, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

Claims

1. A multi-split air conditioning system, characterized in that, The multi-split air conditioning system includes: Multiple outdoor units connected in parallel, each outdoor unit including a compressor, an outdoor heat exchanger, and a defrosting branch, wherein the defrosting branch is used to connect or disconnect the compressor and the outdoor heat exchanger; Multiple indoor units connected in parallel, each indoor unit including an indoor heat exchanger and an indoor fan, the indoor fan being used to regulate the airflow velocity near the indoor heat exchanger; and, The controller is electrically connected to both the outdoor unit and the indoor unit; The controller is configured as follows: Determine whether the outdoor unit in heating mode meets the defrosting conditions; set the outdoor unit that meets the defrosting conditions as the target outdoor unit; Determine whether the outlet temperature of the outdoor heat exchanger in the target outdoor unit is greater than or equal to the first preset temperature; If not, control the target outdoor unit to perform reverse defrosting; control the indoor fan of the indoor unit to stop working; control the defrosting branch to block the compressor and the outdoor heat exchanger; If so, the target outdoor unit is controlled to perform bypass defrosting using the defrosting branch; the indoor fan speed in the indoor unit is controlled to be less than or equal to a first preset speed; the defrosting branch is controlled to connect the compressor and the outdoor heat exchanger, so that part of the refrigerant enters the outdoor heat exchanger from the compressor's exhaust port through the defrosting branch, or the refrigerant enters the outdoor heat exchanger from the compressor's exhaust port, and part of the refrigerant discharged from the outdoor heat exchanger enters the compressor's suction port through the defrosting branch, thereby defrosting the outdoor heat exchanger; Before the controller executes the control of the target outdoor unit to perform bypass defrosting using the defrost branch, the controller is further configured to: control R first outdoor units in shutdown mode to switch to heating mode; R≥1, and R is an integer; Specifically, the controller is configured to switch the R first outdoor units that are in shutdown mode to heating mode. Get the number M of the target outdoor units currently in heating mode, and get the total number N of the outdoor units in the multi-split air conditioning system; M≥1, N≥M, and N and M are both integers; where NM≥R, and NM is the number of the first outdoor units in the multi-split air conditioning system in shutdown mode; Determine whether N / 2 is greater than or equal to M; If so, control M first outdoor units to switch to heating mode and control M target outdoor units to switch to defrost mode; after the M target outdoor units meet the defrost end conditions, the M target outdoor units switch to shutdown mode; If not, control T first outdoor units to switch to heating mode and control A target outdoor units to switch to defrost mode; T≥1, and T is an integer; when M is even, A is M / 2, and when M is odd, A takes the largest integer less than M / 2; Once the A target outdoor units meet the defrosting end conditions, the A target outdoor units are switched to heating mode, and the MA target outdoor units are switched to defrosting mode. Once the MA target outdoor units meet the defrosting end conditions, control the MA target outdoor units to switch to heating mode, and control the T first outdoor units to switch to shutdown mode.

2. The multi-split air conditioning system according to claim 1, characterized in that, The controller executes the command to control the indoor fan speed in the indoor unit to be less than or equal to a first preset speed, specifically configured as follows: Obtain the exhaust pressure of the target outdoor unit; Determine whether the exhaust pressure is greater than or equal to the preset pressure; If not, then the indoor fan will not blow air. Determine whether the target outdoor unit meets the defrosting termination condition; if it does, release the control of the indoor fan. If so, the air outlet temperature of the indoor unit is obtained once every first preset time interval; the number of indoor units is P, P≥1, and P is an integer; it is determined whether the air outlet temperature of each indoor unit is greater than or equal to the second preset temperature. If not, determine the number of indoor units with an air outlet temperature lower than the second preset temperature; If the number of indoor units with an air outlet temperature lower than the second preset temperature is 1, then the indoor fan of the indoor unit is turned off. If the number of indoor units with an air outlet temperature lower than the second preset temperature is greater than 1, then the capacity of the multiple indoor units is sorted, and the indoor fan in the indoor unit with the smallest capacity is turned off. If so, the air speed of the indoor fan of the indoor unit is controlled to be less than or equal to the first preset air speed.

3. The multi-split air conditioning system according to claim 1, characterized in that, The controller executes the command to control the indoor fan speed in the indoor unit to be less than or equal to a first preset speed, specifically configured as follows: Calculate the ratio of the sum of the capacities of indoor units currently in heating mode to the sum of the capacities of outdoor units currently in heating mode; Determine whether the ratio is greater than the judgment value; If not, control the indoor fan speed of the indoor unit to be less than or equal to the first preset speed; If so, calculate the difference between the ratio and the determination value, and calculate the product of the difference and the sum of the capacities of the outdoor units currently in heating mode to obtain the shut-off capacity; Based on the shut-off capacity, the indoor fan of the indoor unit whose capacity is closest to the shut-off capacity is turned off, and the air speed of the indoor fans of the remaining indoor units is controlled to be less than or equal to a first preset air speed.

4. The multi-split air conditioning system according to claim 2 or 3, characterized in that, After the controller executes the control to make the indoor fan speed in the indoor unit less than or equal to the first preset wind speed, the controller is further configured to: determine whether the target outdoor unit meets the defrosting end condition; if it does, then release the control of the indoor fan.

5. The multi-split air conditioning system according to claim 1, characterized in that, The controller executes the control to switch the T first outdoor units to heating mode, specifically configured as follows: Determine if NM is greater than M / 2; If so, control A outdoor units to switch to heating mode, where T = A; If not, control NM first outdoor units to switch to heating mode, where T = NM.

6. The multi-split air conditioning system according to claim 5, characterized in that, After the controller performs the judgment on whether N / 2 is greater than or equal to M, the controller is further configured to: Determine if M is 1; If so, control the i-th first outdoor unit to switch to heating mode, and control the target outdoor unit to switch to defrost mode; where NM≥i≥1, and i is an integer; Once the target outdoor unit meets the defrosting end conditions, control the target outdoor unit to switch to shutdown mode; Once the i-th outdoor unit meets the defrosting conditions, control the i-th outdoor unit to switch to defrosting mode, and control the (i+1)-th outdoor unit to switch to heating mode.

7. The multi-split air conditioning system according to claim 4, characterized in that, The controller is specifically configured to determine whether the target outdoor unit meets the defrosting termination condition. Obtain the outlet air temperature of the target outdoor unit; Determine whether the outlet air temperature is greater than or equal to the third preset temperature; If so, then the target outdoor unit meets the defrosting termination condition; If not, the target outdoor unit does not meet the defrosting termination condition.

Images