Control method of multi-split air conditioner, multi-split air conditioner and storage medium

Abstract

The present invention discloses a control method for a multi-split air conditioner, a multi-split air conditioner and a storage medium. The outdoor heat exchanger of the multi-split air conditioner includes a first heat exchange part and a second heat exchange part, the first heat exchange part and the second heat exchange part are respectively connected to the return air port of the compressor through different first pipelines, and the multi-split air conditioner is provided with a first refrigerant branch between the exhaust port of the compressor and the first heat exchange part. The method includes: obtaining the first capacity of the at least two indoor units and the second capacity of the outdoor unit; when the first capacity and the second capacity reach the first preset condition corresponding to the existence of refrigerant accumulation in the multi-split air conditioner, controlling the first control valve on the first refrigerant branch to open and controlling the second control valve on the first pipeline corresponding to the first heat exchange part to close. The present invention aims to reduce the refrigerant accumulation during the operation of the multi-split air conditioner and improve the heat exchange effect.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning, and in particular to a control method for a multi-split air conditioner, a multi-split air conditioner and a storage medium. Background Art

[0002] Multi-split air conditioners are generally connected to multiple indoor units through an outdoor unit. The multiple indoor units are respectively installed in different indoor spaces. The outdoor unit provides the energy required to regulate the indoor environment for the multiple indoor units. Each indoor unit can be individually adjusted to meet the needs of users in the space where it is set.

[0003] Among them, when the capacity of the indoor unit does not match the capacity of the outdoor unit, it is easy to cause the problem of refrigerant accumulation when the multi-split air conditioner is running, resulting in a decrease in the heat exchange effect and failure to meet user needs. Summary of the invention

[0004] The main purpose of the present invention is to provide a control method for a multi-split air conditioner, a multi-split air conditioner and a storage medium, aiming to reduce refrigerant accumulation during operation of the multi-split air conditioner and improve the heat exchange effect.

[0005] To achieve the above object, the present invention provides a control method for a multi-split air conditioner, the multi-split air conditioner includes at least two indoor units and an outdoor unit, the outdoor unit includes a compressor, an outdoor heat exchanger and a first refrigerant branch provided with a first control valve, the outdoor heat exchanger includes a first heat exchange part and a second heat exchange part, the first heat exchange part and the second heat exchange part are respectively connected to the return air port of the compressor through different first pipelines, a second control valve is provided on the first pipeline corresponding to the first heat exchange part, an inlet of the first refrigerant branch is connected to the exhaust port of the compressor, and an outlet of the first refrigerant branch is connected to the first heat exchange part, and the control method of the multi-split air conditioner includes the following steps:

[0006] Acquire a first capacity of the at least two indoor units and a second capacity of the outdoor unit;

[0007] When the first capacity and the second capacity reach a first preset condition corresponding to the presence of refrigerant accumulation in the multi-split air conditioner, the first control valve is controlled to be opened and the second control valve is controlled to be closed.

[0008] Optionally, the multi-split air conditioner further comprises an air supply branch connecting the refrigerant outlet of the indoor unit and the air supply port of the compressor, the air supply branch is provided with a throttle valve, and after the step of controlling the first control valve to open and the second control valve to close, the step further comprises:

[0009] Obtaining a first characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner;

[0010] When the first characteristic value is greater than a second preset threshold, controlling the throttle valve to increase its opening;

[0011] When the first characteristic value is less than or equal to a first preset threshold, the first control valve is controlled to be closed and the second control valve is controlled to be opened, and the second preset threshold is greater than the first preset threshold.

[0012] Optionally, the air supply branch is further provided with a third control valve, the liquid inlet end of the third control valve is connected to the air return port through a third pipeline, and the third pipeline is provided with a fourth control valve. After the step of obtaining the first characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner, it also includes:

[0013] When the first characteristic value is greater than a second preset threshold, the step of controlling the throttle valve to increase its opening is performed, the third control valve is controlled to be closed, and the fourth control valve is controlled to be opened.

[0014] Optionally, the step of controlling the throttle valve to increase its opening comprises:

[0015] Controlling the throttle valve to increase its opening according to a preset opening adjustment rate, and monitoring a second characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner;

[0016] When the second characteristic value is greater than the second preset threshold value and less than the sum of the second preset threshold value and the preset value, the throttle valve is controlled to maintain the current opening degree.

[0017] Optionally, after the step of monitoring the second characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner, the method further comprises:

[0018] When the second characteristic value is less than or equal to the second preset threshold, the third control valve is controlled to be opened and the fourth control valve is controlled to be closed.

[0019] Optionally, the multi-split air conditioner further includes a second refrigerant branch provided with a fifth control valve, the outdoor heat exchanger further includes a third heat exchange part, the third heat exchange part is connected to the return air port of the compressor through a fourth pipeline, the fourth pipeline is provided with a sixth control valve, the inlet of the second refrigerant branch is connected to the exhaust port of the compressor, the third heat exchange part is connected to the outlet of the second refrigerant branch, and after the steps of controlling the first control valve to open and controlling the second control valve to close, it also includes:

[0020] Obtaining a first characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner;

[0021] When the first characteristic value is greater than a third preset threshold, the fifth control valve is controlled to be opened and the sixth control valve is controlled to be closed.

[0022] Optionally, after the step of controlling the fifth control valve to open and the step of controlling the sixth control valve to close, the method further includes:

[0023] Obtaining a third characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner;

[0024] When the third characteristic value is less than or equal to the third preset threshold, the fifth control valve is controlled to be closed and the sixth control valve is controlled to be opened.

[0025] Optionally, the step of obtaining a first characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner includes:

[0026] Acquire the condensing temperature of the multi-split air conditioner, the indoor temperature of the indoor space regulated by the indoor unit, and the refrigerant temperature flowing out of the indoor unit;

[0027] The first characteristic value is determined according to the condensing temperature, the indoor temperature, and the refrigerant temperature.

[0028] Optionally, the step of determining the first characteristic value according to the condensing temperature, the indoor temperature and the refrigerant temperature includes:

[0029] Determine a first temperature difference between the condensing temperature and the refrigerant temperature, and determine a second temperature difference between the condensing temperature and the indoor temperature;

[0030] The first characteristic value is determined according to the first temperature difference value and the second temperature difference value.

[0031] Optionally, after the step of acquiring the first capacity of the at least two indoor units and the second capacity of the outdoor unit, the method further includes:

[0032] determining a target capacity according to a preset ratio and the second capacity, the target capacity being smaller than the second capacity;

[0033] When the first capacity is less than or equal to the target capacity, it is determined that the first capacity and the second capacity meet the first preset condition.

[0034] Optionally, the control method of the multi-split air conditioner further includes:

[0035] Obtaining the operating mode of the multi-split air conditioner;

[0036] When the operation mode is a heating mode, the step of acquiring the first capacity of the at least two indoor units and the second capacity of the outdoor unit is performed.

[0037] In addition, in order to achieve the above-mentioned purpose, the present application also proposes a multi-split air conditioner, which comprises:

[0038] At least two indoor units;

[0039] An outdoor unit, the outdoor unit includes a compressor, an outdoor heat exchanger and a first refrigerant branch provided with a first control valve, the outdoor heat exchanger includes a first heat exchange part and a second heat exchange part, the first heat exchange part and the second heat exchange part are respectively connected to the return air port of the compressor through different first pipelines, a second control valve is set on the first pipeline corresponding to the first heat exchange part, the inlet of the first refrigerant branch is connected to the exhaust port of the compressor, and the outlet of the first refrigerant branch is connected to the first heat exchange part.

[0040] Optionally, the multi-split air conditioner also includes a second refrigerant branch provided with a fifth control valve, and the outdoor heat exchanger also includes a third heat exchange part, the third heat exchange part is connected to the return air port of the compressor through a fourth pipeline, the fourth pipeline is provided with a sixth control valve, the inlet of the second refrigerant branch is connected to the exhaust port of the compressor, and the third heat exchange part is connected to the outlet of the second refrigerant branch.

[0041] Optionally, the multi-split air conditioner also includes an air supply branch connecting the refrigerant outlet of the indoor unit and the air supply port of the compressor, the air supply branch is provided with a throttle valve and a third control valve, the liquid inlet end of the third control valve is connected to the return air port through a third pipeline, and the third pipeline is provided with a fourth control valve.

[0042] Optionally, the multi-split air conditioner also includes a control device, and the at least two indoor units and the outdoor unit are all connected to the control device. The control device includes: a memory, a processor, and a control program for the multi-split air conditioner stored in the memory and executable on the processor. When the control program of the multi-split air conditioner is executed by the processor, the steps of the control method for the multi-split air conditioner as described in any one of the above items are implemented.

[0043] In addition, in order to achieve the above-mentioned purpose, the present application also proposes a storage medium, on which a control program for a multi-split air conditioner is stored. When the control program for the multi-split air conditioner is executed by a processor, the steps of the control method for the multi-split air conditioner as described in any of the above items are implemented.

[0044] The present invention proposes a control method for a multi-split air conditioner, which is based on a multi-split air conditioner with more than one heat exchange part on an outdoor heat exchanger. When the capacity of the indoor and outdoor units reaches a first preset condition, the method indicates that the multi-split air conditioner is at risk of refrigerant accumulation. At this time, the first control valve on the first refrigerant branch is opened and the second control valve on the first pipeline of the refrigerant outlet of the first heat exchange part is closed, so that the refrigerant flowing out of the compressor flows into the first heat exchange part through the first refrigerant branch, and the refrigerant flowing out of the first heat exchange part is reduced, so that the excess refrigerant that is not needed for the refrigerant circulation of the multi-split air conditioner during the heating operation is stored in the outdoor heat exchanger, thereby reducing the deterioration of the heat exchange effect caused by the refrigerant accumulation during the operation of the multi-split air conditioner, thereby effectively improving the heat exchange effect of the multi-split air conditioner. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A schematic diagram of the structure of a refrigerant system of an embodiment of a multi-split air conditioner of the present invention;

[0046] Figure 2 A schematic diagram of the hardware structure involved in the operation of an embodiment of a multi-split air conditioner of the present invention;

[0047] Figure 3 A schematic diagram of a flow chart of an embodiment of a control method for a multi-split air conditioner according to the present invention;

[0048] Figure 4 A schematic flow chart of another embodiment of a control method for a multi-split air conditioner according to the present invention;

[0049] Figure 5 A flow chart of another embodiment of a control method for a multi-split air conditioner according to the present invention;

[0050] Figure 6 The present invention is a flowchart of another embodiment of a method for controlling a multi-split air conditioner.

[0051] Description of Figure Numbers:

[0052]

[0053] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0054] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0055] The embodiment of the present invention provides a multi-split air conditioner.

[0056] In this embodiment, refer to Figure 1 and Figure 2The multi-split air conditioner includes a control device 1, an outdoor unit 2 and at least two indoor units 3 connected to the outdoor unit 2. The outdoor unit 2 and the at least two indoor units 3 are all connected to the control device 1. Different indoor units 3 are arranged in different indoor spaces. The outdoor unit 2 includes a compressor 21, an outdoor heat exchanger 22, a throttling device 23 and a first refrigerant branch, etc. Each of the indoor units 3 includes an indoor heat exchanger. The refrigerant circulation system of the multi-split air conditioner includes a connected compressor 21, an outdoor heat exchanger 22, a throttling device 23, and at least two indoor heat exchangers.

[0057] The outdoor heat exchanger 22 includes a first heat exchange part 221 and a second heat exchange part 222. In this embodiment, the first heat exchange part 221 and the second heat exchange part 222 can be connected to each other. In other embodiments, the first heat exchange part 221 and the second heat exchange part 222 can also be connected in parallel. The first heat exchange part 221 and the second heat exchange part 222 are respectively connected to the return air port of the compressor 21 through different first pipelines, and the first pipeline corresponding to the first heat exchange part 221 is provided with a second control valve 42. The first heat exchange part 221 and the second heat exchange part 222 are respectively connected to the throttling device 23 through different pipelines.

[0058] The first refrigerant branch is provided with a first control valve 41, the inlet of the first refrigerant branch is connected to the exhaust port of the compressor 21, and the outlet of the first refrigerant branch is connected to the first heat exchange part 221. Specifically, in this embodiment, the pipeline between the second control valve 42 and the first heat exchange part 221 is connected to the outlet of the first refrigerant branch. When the first control valve 41 is opened, the refrigerant discharged from the compressor 21 can flow into the first heat exchange part 221 through the first refrigerant branch; when the first control valve 41 is closed, the refrigerant discharged from the compressor 21 stops flowing into the first heat exchange part 221 through the first refrigerant branch.

[0059] During the operation of the multi-split air conditioner, regardless of whether the first control valve 41 is opened or not, the refrigerant in the second heat exchange part 222 maintains a flowing state. Specifically, during the heating operation of the multi-split air conditioner, the refrigerant maintains flowing from the throttling device 23 into each heat exchange part in the outdoor heat exchanger 22, and the refrigerant flowing into the second heat exchange part 222 flows back to the compressor 21 after heat exchange; when the first control valve 41 is opened, the refrigerant flowing into the first heat exchange part 221 flows back to the compressor 21 after heat exchange, and when the first control valve 41 is closed, the refrigerant flowing into the first heat exchange part 221 is stored in the outdoor heat exchanger 22 or flows back to the compressor 21 after heat exchange through the first heat exchange part 221 and the second heat exchange part 222 in sequence.

[0060] In this embodiment, through the above-mentioned settings, it is possible to adjust the amount of refrigerant participating in the circulation during the operation of the multi-split air conditioner through the first refrigerant branch and the first control valve 41, reduce the refrigerant accumulation in the circulation flow path, and improve the heat exchange effect.

[0061] Further, in another embodiment, referring to Figure 1 The multi-split air conditioner further includes an air supply branch connecting the refrigerant outlet of the indoor unit 3 and the air supply port of the compressor 21. The air supply branch is provided with a throttle valve 47, which can adjust the opening and closing of the air supply branch or the amount of refrigerant flowing in. When the throttle valve 47 is opened, the refrigerant flowing out of the indoor unit 3 is supercooled through the throttle valve 47, and the supercooled refrigerant can enter the air supply port of the compressor 21 for air supply, thereby improving the output capacity of the compressor 21.

[0062] Further, in another embodiment, referring to Figure 1 The multi-split air conditioner also includes a first heat exchanger 5, defining the refrigerant pipeline between the refrigerant outlet of the indoor unit 3 and the outdoor heat exchanger 22 as a second pipeline, defining the pipeline between the throttle valve 47 and the third control valve 43 in the air supply branch as a fifth pipeline, and the second pipeline and the fifth pipeline are connected by heat exchange through the first heat exchanger 5.

[0063] The refrigerant supercooled by the throttle valve 47 enters the fifth pipeline and is heat-exchanged and vaporized with the refrigerant in the second pipeline in the first heat exchanger 5. On the one hand, this further reduces the temperature of the refrigerant entering the outdoor heat exchanger 22, thereby improving the evaporation efficiency of the outdoor heat exchanger 22 and improving the overall heat exchange effect of the multi-split air conditioner. On the other hand, it can reduce the liquid hammer of the compressor 21.

[0064] Further, in another embodiment, referring to Figure 1 The air supply branch is also provided with a third control valve 43, the liquid inlet end of the third control valve 43 is connected to the air return port through a third pipeline, and the third pipeline is provided with a fourth control valve 44.

[0065] When the third control valve 43 is opened, the refrigerant flowing out of the indoor heat exchanger stops entering the air supply port through the air supply branch when the third control valve 43 is closed.

[0066] When the fourth control valve 44 is opened, the refrigerant flowing out of the indoor heat exchanger can flow back to the return air port of the compressor 21 through the third pipeline; when the fourth control valve 44 is closed, the refrigerant flowing out of the indoor heat exchanger stops flowing back to the return air port of the compressor 21 through the third pipeline.

[0067] In this embodiment, the third control valve 43 and the fourth control valve 44 cooperate to adjust the amount of refrigerant flowing into the outdoor heat exchanger 22 while reducing liquid hammer caused by liquid refrigerant directly flowing into the air supply port of the compressor 21, thereby improving the heat exchange effect while protecting the compressor 21.

[0068] Further, in another embodiment, referring to Figure 1The multi-split air conditioner also includes a second refrigerant branch provided with a fifth control valve 45, the outdoor heat exchanger 22 also includes a third heat exchange part 223, the third heat exchange part 223 is connected to the return air port of the compressor 21 through a fourth pipeline, the fourth pipeline is provided with a sixth control valve 46, the inlet of the second refrigerant branch is connected to the exhaust port of the compressor 21, and the third heat exchange part 223 is connected to the outlet of the second refrigerant branch.

[0069] The third heat exchange part 223 may be connected to the first heat exchange part 221 and / or the second heat exchange part 222, or may be connected in parallel to the first heat exchange part 221 and / or the second heat exchange part 222. The third heat exchange part 223 is connected to the first heat exchange part 221 and the second heat exchange part 222 through different pipelines and the throttling device 23.

[0070] Specifically, in this embodiment, the pipeline between the sixth control valve 46 and the third heat exchange part 223 is connected to the outlet of the second refrigerant branch. When the sixth control valve 46 is opened, the refrigerant discharged from the compressor 21 can flow into the third heat exchange part 223 through the second refrigerant branch; when the sixth control valve 46 is closed, the refrigerant discharged from the compressor 21 stops flowing into the third heat exchange part 223 through the second refrigerant branch.

[0071] During the operation of the multi-split air conditioner, regardless of whether the first control valve 41 and the sixth control valve 46 are opened, the refrigerant in the second heat exchange part 222 maintains a flowing state. Specifically, during the heating operation of the multi-split air conditioner, the refrigerant maintains flowing from the throttling device 23 into each heat exchange part in the outdoor heat exchanger 22, and the refrigerant flowing into the second heat exchange part 222 flows back to the compressor 21 after heat exchange; when the sixth control valve 46 is opened, the refrigerant flowing into the third heat exchange part 223 flows back to the compressor 21 after heat exchange, and when the sixth control valve 46 is closed, the refrigerant flowing into the third heat exchange part 223 is stored in the outdoor heat exchanger 22 or flows back to the compressor 21 after heat exchange through the third heat exchange part 223 and the second heat exchange part 222 in sequence, or flows back to the compressor 21 after heat exchange through the third heat exchange part 223, the first heat exchange part 221 and the second heat exchange part 222 in sequence.

[0072] In this embodiment, through the cooperation of the first refrigerant branch and the second refrigerant branch and the control valves arranged thereon, multi-dimensional adjustment of the amount of refrigerant participating in the circulation during the operation of the multi-split air conditioner can be achieved, thereby improving the refrigerant amount adjustment capability in the multi-split air conditioner, further reducing the accumulation of refrigerant in the circulating flow path, and improving the heat exchange effect.

[0073] Further, in another embodiment, referring to Figure 1The multi-split air conditioner further includes a bypass branch connected in parallel with the compressor 21, the bypass branch is provided with a bypass valve 7, and the inlet of the first refrigerant branch and the inlet of the second refrigerant branch are both connected to the liquid inlet end of the bypass valve 7. The refrigerant flowing out of the exhaust port of the compressor 21 can flow through the first refrigerant branch and / or the second refrigerant branch into the corresponding heat exchange part in the outdoor heat exchanger 22.

[0074] Further, in another embodiment, referring to Figure 1 The multi-split air conditioner is an air conditioner with switchable cooling function and heating function, and the multi-split air conditioner may further include a four-way valve 6. The four-way valve 6 has a first interface, a second interface, a third interface, and a fourth interface. The first interface is connected to the exhaust port of the compressor 21, the second interface is connected to the return air port of the compressor 21, one end of the outdoor heat exchanger 22 is connected to the third interface, the other end of the outdoor heat exchanger 22 is connected to one end of the throttling device 23, the other end of the throttling device 23 is connected to one end of the indoor unit 3, and the other end of the indoor unit 3 is connected to the fourth interface.

[0075] When the multi-split air conditioner is in heating operation, the refrigerant discharged from the compressor 21 flows back to the compressor 21 through the first interface, the fourth interface, the indoor heat exchanger, the throttling device 23, the outdoor heat exchanger 22, the third interface, and the second interface in sequence. When the multi-split air conditioner is in cooling operation, the refrigerant discharged from the compressor 21 flows back to the compressor 21 through the first interface, the third interface, the outdoor heat exchanger 22, the throttling device 23, the indoor heat exchanger, the fourth interface, and the second interface in sequence.

[0076] When the air conditioner is in cooling operation, the first pipeline and the fourth pipeline can be switched to be connected to the exhaust port of the compressor 21, the refrigerant outlet of the indoor unit 3 is switched to the refrigerant inlet, and the refrigerant inlet of the indoor unit 3 is switched to the refrigerant outlet.

[0077] In other embodiments, the multi-split air conditioner may also be an air conditioner with a separate heating function. When the multi-split air conditioner is turned on, it operates in heating mode, and the refrigerant discharged from the compressor 21 passes through the indoor heat exchanger, the throttling device 23 and the outdoor heat exchanger 22 in sequence before flowing back to the compressor 21.

[0078] Based on any of the above embodiments, the first control valve 41, the second control valve 42, the third control valve 43, the fourth control valve 44, the fifth control valve 45 and the sixth control valve 46 can be respectively a solenoid valve with a non-adjustable opening or a throttle valve 47 with an adjustable opening. The first control valve 41, the second control valve 42, the third control valve 43, the fourth control valve 44, the fifth control valve 45 and the sixth control valve 46 are all connected to the control device 1, and the control device 1 can be used to control the opening and closing and / or opening adjustment of the above control valves.

[0079] In the embodiment of the present invention, refer to Figure 2The control device 1 of the multi-split air conditioner includes: a processor 1001 (such as a CPU), a memory 1002, a timer 1003, etc. The components in the control device 1 are connected via a communication bus. The memory 1002 can be a high-speed RAM memory or a stable memory (non-volatile memory), such as a disk memory. The memory 1002 can also be a storage device independent of the aforementioned processor 1001.

[0080] Those skilled in the art will understand that Figure 2 The device structure shown in the figure does not constitute a limitation of the device, and may include more or less components than shown in the figure, or combine certain components, or arrange the components differently.

[0081] like Figure 2 As shown, the memory 1002 as a storage medium may include a control program for the multi-split air conditioner. Figure 2 In the device shown, the processor 1001 can be used to call the control program of the multi-split air conditioner stored in the memory 1002, and execute the relevant step operations of the control method of the multi-split air conditioner in the following embodiments.

[0082] An embodiment of the present invention further provides a control method for a multi-split air conditioner, which is applied to the multi-split air conditioner.

[0083] Reference Figure 3 , an embodiment of a control method for a multi-split air conditioner of the present application is proposed. In this embodiment, the control method for the multi-split air conditioner includes:

[0084] Step S10, obtaining a first capacity of the at least two indoor units and a second capacity of the outdoor unit;

[0085] The first capacity may be the sum of the capacities of the at least two indoor units, or may be the sum of the capacities of all indoor units having energy requirements among the at least two indoor units.

[0086] The second capacity may be the rated capacity of the outdoor unit or the actual capacity of the outdoor unit.

[0087] Specifically, in this embodiment, when the multi-split air conditioner is powered on or off for a period of time greater than or equal to a preset period of time and then restarts, step S10 is executed.

[0088] Step S20: When the first capacity and the second capacity reach a first preset condition corresponding to the presence of refrigerant accumulation in the multi-split air conditioner, the first control valve is controlled to be opened and the second control valve is controlled to be closed.

[0089] The first preset condition may be a size relationship, a quantity relationship, or a numerical range that each capacity needs to meet when there is refrigerant accumulation in the multi-split air conditioner.

[0090] In this embodiment, the target capacity is determined according to the preset ratio and the second capacity, and the target capacity is less than the second capacity; when the first capacity is less than or equal to the target capacity, it is determined that the first capacity and the second capacity meet the first preset condition. In this embodiment, the preset ratio is 70%. In other embodiments, the preset ratio may also be 50%, 60% or 80%. The preset ratio may be a preset fixed value, or a value determined according to the actual operation of the multi-split air conditioner. For example, the preset ratio here can be obtained according to the ambient temperature of the environment where the multi-split air conditioner is located and / or the number of indoor units turned on.

[0091] When the first capacity and the second capacity reach the first preset condition, it indicates the risk of refrigerant accumulation in the multi-split air conditioner. At this time, the first control valve is opened to allow part of the refrigerant flowing out of the compressor to flow into the first heat exchange part through the first refrigerant branch, and the second control valve is closed to stop the refrigerant in the first heat exchange part from flowing through its corresponding first pipeline to enter the return air port of the compressor. Based on this, part of the refrigerant flowing out of the compressor can be stored in the outdoor heat exchanger, while the amount of refrigerant flowing into the indoor unit to participate in the refrigerant circulation is reduced, thereby reducing refrigerant accumulation.

[0092] A control method for a multi-split air conditioner is proposed in an embodiment of the present invention. The method is based on a multi-split air conditioner in which an outdoor heat exchanger is provided with more than one heat exchange unit. When the capacity of the indoor and outdoor units reaches a first preset condition, the method indicates that the multi-split air conditioner is at risk of refrigerant accumulation. At this time, the first control valve on the first refrigerant branch is opened and the second control valve on the first pipeline of the refrigerant outlet of the first heat exchange unit is closed, so that the refrigerant flowing out of the compressor flows into the first heat exchange unit through the first refrigerant branch, and the refrigerant flowing out of the first heat exchange unit is reduced, so that the excess refrigerant that is not needed for the refrigerant circulation of the multi-split air conditioner during the heating operation is stored in the outdoor heat exchanger, thereby reducing the deterioration of the heat exchange effect caused by the refrigerant accumulation during the operation of the multi-split air conditioner, thereby effectively improving the heat exchange effect of the multi-split air conditioner.

[0093] Furthermore, in this embodiment, the operation mode of the multi-split air conditioner is obtained; when the operation mode is the heating mode, the step of obtaining the first capacity of the at least two indoor units and the second capacity of the outdoor unit is performed. Since the refrigerant discharged by the compressor directly enters the indoor unit when the multi-split air conditioner is in heating operation, the risk of refrigerant accumulation is greater when the indoor unit capacity is small. At this time, heating control according to the above embodiment is beneficial to improving the heating effect of the multi-split air conditioner.

[0094] In other embodiments, when the operating mode is a cleaning mode, a cooling mode, a sterilization mode, a dehumidification mode or other modes, control can be performed according to the scheme mentioned in the above embodiments, which is beneficial to improving the heat exchange effect of the multi-split air conditioner in different operating modes.

[0095] Further, in this embodiment, when the first capacity and the second capacity do not reach the first preset condition, the first control valve may be controlled to close and the second control valve may be controlled to open.

[0096] Furthermore, in this embodiment, if the multi-split air conditioner includes a third heat exchange part, a second refrigerant branch and related control valves in addition to the first refrigerant branch and the first heat exchange part, when the first capacity and the second capacity reach the first preset condition, the first control valve can be opened and the second control valve can be closed, and the fifth control valve can be controlled to be opened and the sixth control valve can be controlled to be closed. Based on this, part of the refrigerant flowing out of the compressor can be stored in the first heat exchange part and the third heat exchange part, thereby further reducing the accumulation of liquid in the refrigerant circulation system of the multi-split air conditioner and further effectively improving the heat exchange effect of the multi-split air conditioner.

[0097] Furthermore, in this embodiment, if the multi-split air conditioner includes an air supply branch and a throttle valve disposed on the air supply branch in addition to the first refrigerant branch and the second refrigerant branch, when the first capacity and the second capacity reach the first preset condition, the first control valve can be opened and the second control valve can be closed, and the throttle valve can be controlled to increase its opening. The increase in the throttle valve opening can increase the refrigerant flowing into the air supply branch and reduce the refrigerant flowing into the outdoor heat exchanger to participate in the circulation heat exchange, thereby effectively reducing the refrigerant accumulation and improving the heat exchange efficiency of the multi-split air conditioner.

[0098] Furthermore, in the present embodiment, if the multi-split air conditioner air supply branch is also provided with a third control valve, the liquid inlet end of the third control valve is connected to the return air port of the compressor through a third pipeline and the third pipeline is provided with a fourth control valve, when the first capacity and the second capacity reach the first preset condition, the first control valve can be opened and the second control valve can be closed, and the throttle valve can be controlled to increase the opening, and the third control valve can be closed and the fourth control valve can be opened, which can effectively reduce the liquid hammer on the compressor caused by the increase of liquid refrigerant in the air supply branch, thereby improving the heat exchange effect and protecting the compressor.

[0099] Further, based on the above embodiment, another embodiment of the control method of the multi-split air conditioner of the present application is proposed. In this embodiment, after the step S20, it also includes:

[0100] Step S31, obtaining a first characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner;

[0101] The first characteristic value is specifically a value determined according to the operating status parameters of the refrigerant circulation system. The operating status parameters here may include heat exchanger temperature, compressor operating frequency, compressor exhaust temperature and / or exhaust pressure, condensing temperature, evaporating temperature and / or throttling device opening, etc.

[0102] The larger the first characteristic value, the larger the amount of fluid accumulation, and the smaller the first characteristic value, the smaller the amount of fluid accumulation.

[0103] Step S41, when the first characteristic value is greater than a second preset threshold, controlling the throttle valve to increase its opening.

[0104] The first preset threshold is specifically a critical value for identifying whether there is a risk of refrigerant liquid accumulation in the refrigerant circulation system when the first refrigerant branch is open.

[0105] The first characteristic value is greater than the first preset threshold value, indicating that the amount of liquid accumulation is large and there is a risk of refrigerant liquid accumulation in the refrigerant circulation system.

[0106] Step S42: when the first characteristic value is less than or equal to a first preset threshold, the first control valve is controlled to be closed and the second control valve is controlled to be opened, and the second preset threshold is greater than the first preset threshold.

[0107] The throttle valve may be increased according to preset adjustment parameters (such as adjustment amplitude or adjustment rate, etc.), or the adjustment parameters of the throttle valve may be determined according to the first capacity and the second capacity, and the throttle valve may be controlled to increase its current opening according to the determined adjustment parameters.

[0108] When the first characteristic value is less than or equal to the sum of the first preset threshold value and the preset value, the throttle valve can be controlled to maintain the current opening degree.

[0109] In this embodiment, when the first control valve and the second control valve cooperate to realize refrigerant storage, if the air conditioner still faces the risk of liquid accumulation, the throttle valve opening adjustment on the air supply branch is further coordinated to bypass more refrigerant into the low-pressure liquid storage tank to reduce the amount of refrigerant participating in the refrigerant heat exchange cycle, so as to further reduce the problem of liquid accumulation in the refrigerant circulation process, and further improve the heat exchange effect of the multi-split air conditioner.

[0110] Furthermore, in this embodiment, after step S31, it also includes: when the first characteristic value is greater than a second preset threshold, executing the step of controlling the throttle valve to increase the opening, controlling the third control valve to close, and controlling the fourth control valve to open.

[0111] Specifically, in this embodiment, when the first characteristic value is greater than the sum of the second preset threshold and the preset value, the step of controlling the throttle valve to increase the opening is executed, the third control valve is controlled to be closed, and the fourth control valve is controlled to be opened.

[0112] When the third control valve is closed, the refrigerant flowing into the refrigerant branch stops entering the compressor from the air supply port, and when the fourth control valve is opened, the refrigerant flowing into the refrigerant branch enters the compressor from the air return port.

[0113] The increase in the opening of the throttle valve increases the proportion of liquid refrigerant in the air supply branch. If it is directly mixed with the refrigerant passing through the compressor, it is easy to damage the compressor. Based on this, on the basis of increasing the throttle valve, the third control valve is closed and the fourth control valve is opened, so as to improve the heat exchange effect of the multi-split air conditioner while protecting the compressor.

[0114] Furthermore, in order to achieve accurate control of the throttle valve and reduce the damage to the compressor caused by unnecessary opening of the throttle valve, the steps of controlling the throttle valve to increase the opening include:

[0115] Step S411, controlling the throttle valve to increase its opening according to a preset opening adjustment rate, and monitoring a second characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner;

[0116] The preset opening adjustment rate is the amplitude adjustment value of the throttle valve opening per unit time. The preset opening adjustment rate can be a preset fixed rate, or a rate selected from more than one preset fixed rate according to the first capacity and the second capacity.

[0117] During the throttle valve increase process, the second characteristic value is detected in real time. The detection process of the second characteristic value is the same as that of the first characteristic value, which will not be described in detail here.

[0118] Step S412: when the second characteristic value is greater than the second preset threshold value and less than the sum of the second preset threshold value and the preset value, control the throttle valve to maintain the current opening.

[0119] The preset value may be 0.1. The second characteristic value is greater than the second preset threshold value and less than the sum of the second preset threshold value and the preset value (that is, the second preset threshold value + A), indicating that the risk of liquid accumulation in the multi-split air conditioner is low at this time, and the impact on the heat exchange effect is small. At this time, continuing to increase the throttle valve opening can effectively achieve an effective balance between the heat exchange effect of the multi-split air conditioner and the protection of the compressor.

[0120] Step S413: when the second characteristic value is less than or equal to the second preset threshold, control the third control valve to open and control the fourth control valve to close.

[0121] When the second characteristic value is less than or equal to the second preset threshold value, it indicates that the current liquid accumulation risk of the multi-split air conditioner is controllable. At this time, the third control valve is opened and the fourth control valve is closed. At the same time, the throttle valve can operate at an opening determined by the state parameters of the multi-split air conditioner related to the air replenishment enthalpy increase demand, thereby ensuring that the air replenishment enthalpy increase increases the output capacity of the compressor, so as to further improve the heat exchange effect of the multi-split air conditioner.

[0122] Further, in this embodiment, referring to Figure 4 , after step S31, further comprising:

[0123] Step S401, when the first characteristic value is greater than the sum of the second preset threshold and the preset value, controlling the throttle valve to increase its opening, controlling the third control valve to close, and controlling the fourth control valve to open;

[0124] Step S402, when the first characteristic value is less than or equal to the second preset threshold, controlling the fourth control valve to close, and controlling the third control valve and the throttle valve to adaptively adjust according to their corresponding preset logics;

[0125] Step S403: when the first characteristic value is less than the first preset threshold, the first control valve is controlled to be closed and the second control valve is controlled to be opened.

[0126] Further, based on any of the above embodiments, another embodiment of the control method of the multi-split air conditioner of the present application is proposed. Figure 5 , after step S20, further comprising:

[0127] Step S32, obtaining a first characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner;

[0128] Step S43: when the first characteristic value is greater than a third preset threshold, the fifth control valve is controlled to be opened and the sixth control valve is controlled to be closed.

[0129] The third preset threshold is specifically a critical value used to distinguish whether the risk of refrigerant liquid accumulation is too great (that is, the amount of liquid accumulation is too large).

[0130] The fifth control valve is opened to allow part of the refrigerant flowing out of the compressor to flow into the third heat exchange part through the second refrigerant branch, and the sixth control valve is closed to stop the refrigerant in the third heat exchange part from flowing through its corresponding fourth pipeline to enter the return air port of the compressor. Based on this, on the basis of storing refrigerant through the first heat exchange part, the third heat exchange part can also store refrigerant, so that the amount of refrigerant flowing out of the outdoor heat exchanger as a whole is reduced and the amount of stored refrigerant is increased, thereby further reducing the amount of refrigerant participating in the circulation of the multi-split air conditioner.

[0131] In this embodiment, during the process of storing excess refrigerant through the cooperation of the first control valve, the second control valve, the first refrigerant branch and the first heat exchange part, when it is determined based on the first characteristic value detection that the amount of accumulated liquid is still excessive, the storage amount of the refrigerant is further increased through the cooperation of the fifth control valve, the sixth control valve, the second refrigerant branch and the third heat exchange part, thereby further reducing the refrigerant accumulation and improving the heat exchange effect.

[0132] Furthermore, in this embodiment, in step S20, the first control valve is opened and the second control valve is closed, while the fifth control valve can be closed and the sixth control valve is opened. Based on this, the refrigerant is first stored in the first heat exchange part, while the second heat exchange part and the third heat exchange part maintain normal heat exchange, thereby reducing liquid accumulation while ensuring the heat exchange efficiency of the outdoor heat exchanger to improve the heat exchange effect.

[0133] Further, in this embodiment, when the first characteristic value is less than or equal to the third preset threshold value, if step S20 further includes step S31, step S41 and step S42, step S31 and step S32 can be combined into one step, and the third preset threshold value is greater than the first preset threshold value, the second preset threshold value and the sum of the second preset threshold value and the preset value. Based on this, when the first characteristic value is greater than the second preset threshold value and less than or equal to the third preset threshold value, the throttle valve can be controlled to open, the fifth control valve can be controlled to close, and the sixth control valve can be controlled to open; when the first characteristic value is greater than the third preset value, the throttle valve can be controlled to open, the fifth control valve can be controlled to open, and the sixth control valve can be controlled to close. Alternatively, when the first characteristic value is greater than the second preset threshold value and less than or equal to the third preset threshold value, the throttle valve can be controlled to open, the third control valve can be controlled to close, the fourth control valve can be controlled to open, the fifth control valve can be controlled to close, and the sixth control valve can be controlled to open; when the first characteristic value is greater than the third preset value, the throttle valve can be controlled to open, the third control valve can be controlled to close, the fourth control valve can be controlled to open, the fifth control valve can be controlled to open, and the sixth control valve can be controlled to close.

[0134] In other embodiments, when the above-mentioned steps S31, S41 and S42 are not included after step S20, when the first characteristic value is less than or equal to the first preset threshold, the first control valve can be controlled to close and the second control valve can be controlled to open.

[0135] Furthermore, in this embodiment, after step S43, it also includes: obtaining a third characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner; when the third characteristic value is less than or equal to the third preset threshold, controlling the fifth control valve to close and controlling the sixth control valve to open.

[0136] The detection process of the third eigenvalue is the same as that of the first eigenvalue, which will not be described here.

[0137] Specifically, when the closing time of the fifth control valve reaches a preset time, the sixth control valve is controlled to open.

[0138] When the third characteristic value is less than or equal to the third preset threshold value, it indicates that the risk of liquid accumulation in the current multi-split air conditioner is reduced. At this time, there is no need to store a large amount of excess refrigerant. In order to ensure that the multi-split air conditioner has sufficient refrigerant to participate in the heat exchange cycle, the fifth control valve is closed and the sixth control valve is opened at this time to reduce the number of heat exchange parts used to store refrigerant, so as to effectively improve the heat exchange effect of the multi-split air conditioner.

[0139] Furthermore, after controlling the fifth control valve to close and controlling the sixth control valve to open, a step of obtaining a first characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner may be performed.

[0140] Further, based on any of the above embodiments, another embodiment of the control method of the multi-split air conditioner of the present application is proposed. Figure 6 The step of obtaining a first characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner comprises:

[0141] Step S301, obtaining the condensing temperature of the multi-split air conditioner, the indoor temperature of the indoor space regulated by the indoor unit, and the refrigerant temperature flowing out of the indoor unit;

[0142] The condensing temperature can be specifically calculated based on the exhaust pressure and / or exhaust temperature of the compressor.

[0143] The indoor temperature can be specifically detected by a temperature sensor installed in the indoor space.

[0144] The refrigerant temperature can be specifically detected by a temperature sensor disposed at the inlet of the fourth pipeline.

[0145] Step S302: determining the first characteristic value according to the condensing temperature, the indoor temperature and the refrigerant temperature.

[0146] Different condensing temperatures, different indoor temperatures, and different refrigerant temperatures correspond to different first characteristic values. Specifically, a correspondence between the condensing temperature, indoor temperature, refrigerant temperature, and the first characteristic value may be established in advance, and the correspondence may be in the form of a calculation relationship, a mapping relationship, etc. Based on the correspondence, the first characteristic value corresponding to the current condensing temperature, indoor temperature, and refrigerant temperature may be determined.

[0147] In this embodiment, a first temperature difference between the condensing temperature and the refrigerant temperature is determined, and a second temperature difference between the condensing temperature and the indoor temperature is determined; the first characteristic value is determined according to the first temperature difference and the second temperature difference. In this embodiment, the ratio of the first temperature difference to the second temperature difference is used as the first characteristic value. In other embodiments, the difference between the first temperature difference and the second temperature difference may also be used as the first characteristic value.

[0148] In this embodiment, the combination of the condensing temperature, indoor temperature and refrigerant temperature can accurately reflect the actual heat exchange situation of the indoor unit under the current output of the outdoor unit. Therefore, the condensing temperature, indoor temperature and refrigerant temperature are combined, especially the first temperature difference value and the second temperature difference value determined by these temperatures, to determine the first characteristic value characterizing the amount of liquid accumulation, which is beneficial to improve the accuracy of the liquid accumulation risk represented by the first characteristic value, thereby achieving accurate regulation of the above-mentioned different valve bodies based on the first characteristic value, effectively reducing the refrigerant liquid accumulation while protecting the compressor and improving the heat exchange effect.

[0149] In other embodiments, the first characteristic value may be determined according to one of the first temperature difference value and the second temperature difference value, or according to one or two of the condensing temperature, the refrigerant temperature, and the indoor temperature.

[0150] The second eigenvalue and the third eigenvalue mentioned above can also be determined by analogy according to step S301 and step S302 here.

[0151] In addition, an embodiment of the present invention further proposes a storage medium, on which a control program for a multi-split air conditioner is stored. When the control program for the multi-split air conditioner is executed by a processor, the relevant steps of any embodiment of the control method for the multi-split air conditioner are implemented.

[0152] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0153] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0154] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, including a number of instructions for enabling a terminal device (which can be a mobile phone, a computer, a server, a multi-split air conditioner, or a network device, etc.) to execute the methods described in each embodiment of the present invention.

[0155] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A control method for a multi-split air conditioner, characterized in that: The multi-split air conditioner includes at least two indoor units and an outdoor unit, the outdoor unit includes a compressor, an outdoor heat exchanger and a first refrigerant branch provided with a first control valve, the outdoor heat exchanger includes a first heat exchange part and a second heat exchange part, when the multi-split air conditioner is in a heating mode, the first heat exchange part and the second heat exchange part are respectively connected to the return air port of the compressor through different first pipelines, a second control valve is provided on the first pipeline corresponding to the first heat exchange part, an inlet of the first refrigerant branch is connected to the exhaust port of the compressor, and a pipeline between the second control valve and the first heat exchange part is connected to an outlet of the first refrigerant branch, and the control method of the multi-split air conditioner includes the following steps: When the operation mode of the multi-split air conditioner is a heating mode, obtaining the first capacity of the at least two indoor units and the second capacity of the outdoor unit; When the first capacity and the second capacity reach a first preset condition corresponding to the presence of refrigerant accumulation in the multi-split air conditioner, the first control valve is controlled to be opened and the second control valve is controlled to be closed; Wherein, after the step of obtaining the first capacity of the at least two indoor units and the second capacity of the outdoor unit, the method further includes: determining a target capacity according to a preset ratio and the second capacity, the target capacity being smaller than the second capacity; When the first capacity is less than or equal to the target capacity, it is determined that the first capacity and the second capacity meet the first preset condition.

2. The control method of a multi-split air conditioner according to claim 1, characterized in that: The multi-split air conditioner further includes an air supply branch connecting the refrigerant outlet of the indoor unit and the air supply port of the compressor in the heating mode, the air supply branch is provided with a throttle valve, and after the step of controlling the first control valve to open and the second control valve to close, it also includes: Obtaining a first characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner; When the first characteristic value is greater than a second preset threshold, controlling the throttle valve to increase its opening; When the first characteristic value is less than or equal to a first preset threshold, the first control valve is controlled to be closed and the second control valve is controlled to be opened, and the second preset threshold is greater than the first preset threshold.

3. The control method of a multi-split air conditioner according to claim 2, characterized in that: The air supply branch is further provided with a third control valve. When the multi-split air conditioner is in heating mode, the liquid inlet end of the third control valve is connected to the air return port through a third pipeline. The third pipeline is provided with a fourth control valve. After the step of obtaining the first characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner, it also includes: When the first characteristic value is greater than a second preset threshold value, the step of controlling the throttle valve to increase its opening is performed, the third control valve is controlled to be closed, and the fourth control valve is controlled to be opened.

4. The control method of a multi-split air conditioner according to claim 3, characterized in that: The step of controlling the throttle valve to increase its opening degree comprises: Controlling the throttle valve to increase its opening according to a preset opening adjustment rate, and monitoring a second characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner; When the second characteristic value is greater than the second preset threshold value and less than the sum of the second preset threshold value and the preset value, the throttle valve is controlled to maintain the current opening.

5. The control method of a multi-split air conditioner according to claim 4, characterized in that: After the step of monitoring the second characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner, the method further includes: When the second characteristic value is less than or equal to the second preset threshold, the third control valve is controlled to be opened and the fourth control valve is controlled to be closed.

6. The control method of a multi-split air conditioner according to claim 1, characterized in that: The multi-split air conditioner further includes a second refrigerant branch provided with a fifth control valve, the outdoor heat exchanger further includes a third heat exchange unit, when the multi-split air conditioner is in heating mode, the third heat exchange unit is connected to the return air port of the compressor through a fourth pipeline, the fourth pipeline is provided with a sixth control valve, the inlet of the second refrigerant branch is connected to the exhaust port of the compressor, the third heat exchange unit is connected to the outlet of the second refrigerant branch, after the steps of controlling the first control valve to open and controlling the second control valve to close, it also includes: Obtaining a first characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner; When the first characteristic value is greater than a third preset threshold, the fifth control valve is controlled to be opened and the sixth control valve is controlled to be closed.

7. The control method of a multi-split air conditioner according to claim 6, characterized in that: After the step of controlling the fifth control valve to open and the sixth control valve to close, the method further includes: Obtaining a third characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner; When the third characteristic value is less than or equal to the third preset threshold, the fifth control valve is controlled to be closed and the sixth control valve is controlled to be opened.

8. The control method of a multi-split air conditioner according to claim 2 or 6, characterized in that: The step of obtaining a first characteristic value of the amount of liquid accumulation of the refrigerant in the multi-split air conditioner comprises: Acquire the condensing temperature of the multi-split air conditioner, the indoor temperature of the indoor space regulated by the indoor unit, and the refrigerant temperature flowing out of the indoor unit; The first characteristic value is determined according to the condensing temperature, the indoor temperature, and the refrigerant temperature.

9. The control method of a multi-split air conditioner according to claim 8, characterized in that: The step of determining the first characteristic value according to the condensing temperature, the indoor temperature and the refrigerant temperature comprises: Determine a first temperature difference between the condensing temperature and the refrigerant temperature, and determine a second temperature difference between the condensing temperature and the indoor temperature; The first characteristic value is determined according to the first temperature difference value and the second temperature difference value.

10. A multi-split air conditioner, characterized in that: The multi-split air conditioner comprises: At least two indoor units; An outdoor unit, the outdoor unit comprising a compressor, an outdoor heat exchanger and a first refrigerant branch provided with a first control valve, the outdoor heat exchanger comprising a first heat exchange part and a second heat exchange part, when the multi-split air conditioner is in a heating mode, the first heat exchange part and the second heat exchange part are respectively connected to the return air port of the compressor through different first pipelines, a second control valve is provided on the first pipeline corresponding to the first heat exchange part, an inlet of the first refrigerant branch is connected to the exhaust port of the compressor, and a pipeline between the second control valve and the first heat exchange part is connected to the outlet of the first refrigerant branch; A control device, wherein the at least two indoor units and the outdoor unit are connected to the control device, and the control device comprises: a memory, a processor, and a control program for a multi-split air conditioner stored in the memory and executable on the processor, wherein the control program for the multi-split air conditioner, when executed by the processor, implements the steps of a control method for a multi-split air conditioner as described in any one of claims 1 to 9.

11. The multi-split air conditioner according to claim 10, characterized in that: The multi-split air conditioner also includes a second refrigerant branch provided with a fifth control valve, and the outdoor heat exchanger also includes a third heat exchange unit. When the multi-split air conditioner is in a heating mode, the third heat exchange unit is connected to the return air port of the compressor through a fourth pipeline, and the fourth pipeline is provided with a sixth control valve. The inlet of the second refrigerant branch is connected to the exhaust port of the compressor, and the third heat exchange unit is connected to the outlet of the second refrigerant branch.

12. The multi-split air conditioner according to claim 10, characterized in that: The multi-split air conditioner also includes an air supply branch connecting the refrigerant outlet of the indoor unit and the air supply port of the compressor, the air supply branch is provided with a throttle valve and a third control valve, when the multi-split air conditioner is in heating mode, the liquid inlet end of the third control valve is connected with the return air port through a third pipeline, and the third pipeline is provided with a fourth control valve.

13. A storage medium, characterized in that: The storage medium stores a control program for a multi-split air conditioner, and when the control program for the multi-split air conditioner is executed by a processor, the steps of the control method for a multi-split air conditioner as described in any one of claims 1 to 9 are implemented.

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