A multi-split air conditioning system and a control method thereof

Abstract

The application provides a multi-split air conditioning system and a control method thereof, and relates to the technical field of air conditioners. The air conditioning system comprises: a plurality of indoor units, each indoor unit comprising an indoor throttling device; and a controller configured to: in response to the multi-split air conditioning system operating in a cooling mode, increase the number of operating indoor units, adjust the opening degree of the indoor throttling device of the operating indoor unit to an initial opening degree, and the operating indoor unit being a starting operating indoor unit; within a first preset time period after the number of operating indoor units is increased, keep the opening degree of the indoor throttling device of the operating indoor unit unchanged under the condition that a first preset condition is met; and wherein the first preset condition comprises: the outdoor environment temperature being less than or equal to a first temperature; the superheat degree of the operating indoor unit being less than or equal to a first superheat degree, the first superheat degree being greater than a target superheat degree; the compressor discharge superheat degree being less than or equal to a first discharge superheat degree; and the compressor suction pressure being greater than or equal to a minimum suction pressure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air conditioners, and in particular to a multi-split air conditioning system and a control method thereof. BACKGROUND

[0002] At present, a multi-split air conditioning system is composed of one or more outdoor units and multiple indoor units to realize refrigeration, heating and other functions. As a multi-end and variable refrigerant flow refrigeration / heat system, the multi-split air conditioning system has the characteristics of flexible control, energy saving and low operation cost, and is increasingly widely used in small and medium-sized buildings.

[0003] With the increase in the number of indoor units of the multi-split air conditioning system, the required refrigerant also increases. In addition, the connection pipe between the indoor unit and the outdoor unit of the multi-split air conditioning system is relatively long, and the refrigerant charging amount is relatively large. Therefore, in the prior art, the opening adjustment of the throttling device is adjusted according to the target superheat during the process of increasing the number of indoor units. However, the target superheat cannot truly reflect the operation of the running indoor unit in the initial stage of increasing the number of indoor units of the multi-split air conditioning system. Therefore, in the related art, the opening of the indoor throttling device in the running indoor unit is adjusted based on the difference between the superheat of the running indoor unit and the target superheat after the number of running indoor units is increased, which is easy to adjust the opening of the indoor throttling device in the running indoor unit too large, thereby causing the problem of liquid accumulation in the gas-liquid separator. When the liquid accumulation in the gas-liquid separator is too much, it may cause the compressor to return liquid, reduce the oil viscosity, and cause wear to the compressor. SUMMARY

[0004] Embodiments of the present application provide a multi-split air conditioning system and a control method thereof for preventing excessive liquid accumulation in a gas-liquid separator in the multi-split air conditioning system.

[0005] To achieve the above object, the embodiments of the present application adopt the following technical solutions:

[0006] In a first aspect, a multi-split air conditioning system is provided, which comprises:

[0007] at least one outdoor unit, each outdoor unit comprising a compressor, an outdoor heat exchanger and a gas-liquid separator;

[0008] a plurality of indoor units, each indoor unit comprising an indoor heat exchanger and an indoor throttling device;

[0009] a controller configured to:

[0010] in response to the multi-split air conditioning system operating in a refrigeration mode increasing the number of running indoor units, adjusting the opening of the indoor throttling device in the running indoor unit to an initial opening;

[0011] In a first preset time period after the number of operating indoor units is increased, the opening degree of the indoor throttling device of the operating indoor unit is kept unchanged in a case where a first preset condition is met.

[0012] The first preset condition includes:

[0013] The outdoor ambient temperature is less than or equal to a first temperature.

[0014] The overheat degree of the operating indoor unit is less than or equal to a first overheat degree, and the first overheat degree is greater than a target overheat degree.

[0015] The compressor discharge overheat degree is less than or equal to a first discharge overheat degree.

[0016] The compressor suction pressure is greater than or equal to a minimum suction pressure.

[0017] Since the overheat degree of the operating indoor unit of the multi-split air conditioning system in a period of time after the number of operating indoor units is increased cannot truly reflect the operating condition of the operating indoor unit, in the related art, the opening degree of the indoor throttling device of the operating indoor unit is adjusted based on the difference between the overheat degree of the operating indoor unit and the target overheat degree after the number of operating indoor units is increased, which is likely to adjust the opening degree of the indoor throttling device of the operating indoor unit to be too large, thereby causing the gas-liquid separator to produce liquid accumulation. In view of this, in the present application, the opening degree adjustment mode taking the target overheat degree as the adjustment target is not used in a preset time period after the number of operating indoor units is increased, and the opening degree of the indoor throttling device of the operating indoor unit is not adjusted in a case where a first preset condition is met (i.e., in a case where the multi-split air conditioning system can still operate normally when the outdoor ambient temperature is low), thereby avoiding adjusting the opening degree of the indoor throttling device of the operating indoor unit to be too large in the preset time period, and further avoiding causing the gas-liquid separator to produce liquid accumulation.

[0018] In some embodiments, the controller of the multi-split air conditioning system is further configured to, in a first preset time period after the number of operating indoor units is increased, reduce the opening degree of the indoor throttling device of the operating indoor unit in a case where a second preset condition is met; and the second preset condition includes that the outdoor ambient temperature is less than or equal to a first temperature, the compressor discharge overheat degree is less than or equal to a second discharge overheat degree, the second discharge overheat degree is less than the first discharge overheat degree, the difference between the compressor discharge temperature of the current detection period and the compressor discharge temperature of the last detection period is less than or equal to a second temperature, the overheat degree of the operating indoor unit is less than or equal to a second overheat degree, the second overheat degree is less than the first overheat degree, and the compressor suction pressure is greater than or equal to a minimum suction pressure.

[0019] It can be understood that the compressor discharge superheat is less than or equal to the second discharge superheat, the second discharge superheat is less than the first discharge superheat, and the difference between the compressor discharge temperature of the current detection period and the compressor discharge temperature of the last detection period is less than or equal to the second temperature, which indicates that the discharge superheat of the compressor is rapidly decreasing. Therefore, the present application increases the discharge superheat by reducing the opening degree of the indoor throttling device when the second preset condition is met, so as to prevent the liquid refrigerant returning to the compressor from causing damage to the compressor.

[0020] In some embodiments, the controller of the multi-split air conditioning system is further configured to, after increasing the number of operating indoor units, reduce the opening degree of the indoor throttling device of the operating indoor unit when a third preset condition is met within a first preset time period; wherein the third preset condition includes: the outdoor environment temperature is greater than a third temperature, the third temperature is greater than the first temperature; the multi-split air conditioning system reduces the number of compressors in the operating state; the compressor suction pressure is greater than or equal to the minimum suction pressure; the compressor discharge pressure is less than or equal to the maximum discharge pressure; and the compressor discharge temperature is less than a fourth temperature.

[0021] It can be understood that the outdoor environment temperature greater than the third temperature indicates that the multi-split air conditioning system is in a high-temperature refrigeration working condition. Due to the high indoor environment temperature, as the operating frequency of the multi-split air conditioning system increases, some outdoor units will be shut down when the discharge pressure or the discharge temperature of the outdoor unit reaches the protection value. However, as the number of operating indoor units increases, the amount of refrigerant required also increases, resulting in a large amount of refrigerant concentrated in the operating outdoor unit, and thus causing the amount of refrigerant in the gas-liquid separator of the operating outdoor unit to be excessive. In the prior art, increasing the opening degree of the indoor throttling device according to the target superheat will result in incomplete evaporation of the indoor unit, which will cause a large amount of liquid refrigerant to return to the gas-liquid separator of the outdoor unit, resulting in the problem of liquid accumulation in the gas-liquid separator. To prevent the above situation from occurring, the present application reduces the opening degree of the indoor throttling device of the operating indoor unit when the third preset condition is met (i.e., when the number of compressors is reduced, but the multi-split air conditioning system continues to operate normally), so as to prevent the gas-liquid separator in the operating outdoor unit from storing a large amount of liquid due to the reduction in the number of operating compressors, thereby preventing damage to the compressor.

[0022] In some embodiments, the controller of the multi-split air conditioning system is further configured to, in response to the instruction indicating that the multi-split air conditioning system starts the cooling mode, acquire the capacities of the operating indoor units, and calculate a first total opening degree based on the capacities of the operating indoor units; acquire the capacities of the operating outdoor heat exchangers, and calculate a second total opening degree based on the capacities of the operating outdoor heat exchangers; select the minimum value from the first total opening degree and the second total opening degree as a target total opening degree; calculate the initial opening degrees of the indoor throttling devices of the operating indoor units based on the target total opening degree and the capacities of the operating indoor units; and adjust the opening degrees of the indoor throttling devices of the operating indoor units based on the initial opening degrees of the indoor throttling devices of the operating indoor units.

[0023] It can be understood that the total opening degree of the indoor throttling devices derived from the total capacity of the operating indoor units and the total opening degree of the indoor throttling devices derived from the total capacity of the operating outdoor heat exchangers can be different. Therefore, the initial opening degrees of the throttling devices of the operating indoor units can be calculated by taking the minimum value of the two as the target total opening degree, and the opening degrees of the throttling devices of the operating indoor units can be adjusted based on the initial opening degrees, which can prevent the opening degrees of the throttling devices of the operating indoor units from being too large to cause more liquid accumulation in the gas-liquid separator.

[0024] In some embodiments, the controller is further configured to adjust the opening degrees of the indoor throttling devices of the operating indoor units based on the initial opening degrees of the indoor throttling devices of the operating indoor units, and specifically perform the following steps: when the initial opening degree of the indoor throttling device of the operating indoor unit is greater than or equal to a preset minimum opening degree and less than or equal to a preset maximum opening degree, the opening degree of the indoor throttling device of the operating indoor unit is adjusted to the corresponding initial opening degree; or, when the initial opening degree of the indoor throttling device of the operating indoor unit is greater than the preset maximum opening degree, the opening degree of the indoor throttling device of the operating indoor unit is adjusted to the preset maximum opening degree; or, when the initial opening degree of the indoor throttling device of the operating indoor unit is less than the preset minimum opening degree, the opening degree of the indoor throttling device of the operating indoor unit is adjusted to the preset minimum opening degree.

[0025] It can be understood that by limiting the upper and lower limits of the initial opening degree, the opening degree of the indoor throttling device of the operating indoor unit can be prevented from being adjusted too large or too small, thereby ensuring the normal operation of the multi-split air conditioning system.

[0026] In some embodiments, the controller of the multi-split air conditioning system is further configured to, within a second preset time period after the multi-split air conditioning system starts the cooling mode, reduce the opening degree of the indoor throttling device of the operating indoor unit if a fourth preset condition or a fifth preset condition is met; the fourth preset condition includes that the compressor discharge superheat is less than or equal to a second discharge superheat, and the superheat of the operating indoor unit is less than or equal to a third superheat; the fifth preset condition includes that the compressor discharge superheat is less than or equal to a third discharge superheat, the compressor suction pressure is greater than a minimum suction pressure, and the outdoor environment temperature is less than or equal to a first temperature, and the third discharge superheat is less than the second discharge superheat.

[0027] In the related art, the opening degree of the indoor throttling device is increased when the compressor superheat is greater than the target superheat, but the opening degree of the indoor throttling device may be too large, which can cause the gas-liquid separator to have too much liquid accumulation. In the present application, the opening degree of the indoor throttling device of the operating indoor unit is reduced when the fourth preset condition or the fifth preset condition is met, so as to correct the opening degree of the indoor throttling device of the operating indoor unit on the basis of ensuring the reliability of the compressor. Although the superheat of the compressor exceeds the control target in the above process, the excessive opening degree of the indoor throttling device is avoided, which can cause too much liquid accumulation in the gas-liquid separator and damage the compressor.

[0028] In some embodiments, the controller of the multi-split air conditioning system is further configured to determine the operating frequency of the compressor according to the capacity of each operating indoor unit, and there is a positive correlation between the operating frequency of the compressor and the capacity of each operating indoor unit.

[0029] It can be understood that the operating frequency of the compressor before the number of operating indoor units is increased is related to the capacity of the operating indoor unit. When the number of operating indoor units increases, the capacity of the operating indoor unit increases, the target frequency of the compressor also increases, and the circulating amount of the refrigerant also rapidly increases.

[0030] In some embodiments, within a first preset time period after the number of operating indoor units is increased, the change amount of the operating frequency of the compressor in the operating state is less than or equal to a preset frequency change amount.

[0031] It can be understood that controlling the frequency of the compressor within the first preset time period after the number of operating indoor units is increased can avoid the situation that the circulating amount of the refrigerant rapidly increases and causes too much liquid accumulation in the gas-liquid separator.

[0032] In some embodiments, the multi-split air conditioning system further comprises a bypass valve, one end of the bypass valve being connected to the exhaust port of the compressor, and the other end of the bypass valve being connected to the suction port of the gas-liquid separator; the controller of the multi-split air conditioning system is further configured to: when the multi-split air conditioning system is running in the cooling mode and the outdoor ambient temperature is less than or equal to the first temperature, if the sixth preset condition is met, the bypass valve is controlled to be opened; after the bypass valve is opened, if the seventh preset condition is met, the bypass valve is controlled to be closed; wherein the sixth preset condition comprises at least one of the following: the compressor exhaust superheat is less than the fourth exhaust superheat, or the compressor suction superheat is less than the first suction superheat; the seventh preset condition comprises at least one of the following: the opening time of the bypass valve reaches the third preset time, the compressor exhaust superheat is greater than or equal to the fifth exhaust superheat, or the compressor suction superheat is greater than or equal to the second suction superheat.

[0033] It can be understood that when the multi-split air conditioning system is running in the low-temperature cooling condition, if the exhaust superheat or the suction superheat of the compressor is too low, the compressor may be back-flushed. In this case, the bypass valve needs to be opened to increase the suction superheat of the compressor and reduce the back-flush amount of the compressor. After the bypass valve is opened for a period of time and the exhaust superheat and the suction superheat of the compressor reach a reasonable range, the bypass valve can be closed to prevent the exhaust superheat or the suction superheat of the compressor from being too high to damage the compressor.

[0034] In a second aspect, the embodiments of the present application provide a control method applied to the above multi-split air conditioning system, the method comprising: in response to the multi-split air conditioning system running in the cooling mode and the number of running indoor units being increased, adjusting the opening degree of the indoor throttling device of the running indoor unit to an initial opening degree; within a first preset time period after the number of running indoor units is increased, keeping the opening degree of the indoor throttling device of the running indoor unit unchanged in the case where the first preset condition is met; wherein the first preset condition comprises: the outdoor ambient temperature is less than or equal to the first temperature; the overheat degree of the running indoor unit is less than or equal to the first overheat degree, the first overheat degree being greater than the target overheat degree; the compressor exhaust superheat is less than or equal to the first exhaust superheat; and the compressor suction pressure is greater than or equal to the minimum suction pressure.

[0035] In a third aspect, the embodiments of the present application provide a controller, comprising: one or more processors; one or more memories; wherein the one or more memories are used to store computer program codes, the computer program codes comprising computer instructions, when the one or more processors execute the computer instructions, the controller executes the control method provided in the second aspect.

[0036] In a fourth aspect, the embodiments of the present application provide a computer readable storage medium, which comprises computer instructions. When the computer instructions are controlled on a computer, the computer executes the method provided in the second aspect and possible implementation manners.

[0037] In a fifth aspect, the embodiments of the present application provide a computer program product, which can be directly loaded into a memory and contains software codes. The computer program product can realize the method provided in the second aspect and possible implementation manners after being loaded and executed by a computer.

[0038] It should be noted that the computer instructions described above can be stored on the computer readable storage medium in whole or in part. The computer readable storage medium can be packaged together with the processor of the controller or packaged separately from the processor of the controller, and the present application does not limit this.

[0039] The beneficial effects of the second aspect to the fifth aspect described in the present application can be analyzed with reference to the beneficial effects of the first aspect, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 A structural schematic diagram of a multi-split air conditioning system provided by the embodiments of the present application is shown in the figure;

[0041] Figure 2 A structural schematic diagram of another multi-split air conditioning system provided by the embodiments of the present application is shown in the figure;

[0042] Figure 3 A structural schematic diagram of another multi-split air conditioning system provided by the embodiments of the present application is shown in the figure;

[0043] Figure 4 A hardware structural schematic diagram of a controller provided by the embodiments of the present application is shown in the figure;

[0044] Figure 5 A flowchart of a control method of a multi-split air conditioning system provided by the embodiments of the present application is shown in the figure;

[0045] Figure 6 A flowchart of another control method of a multi-split air conditioning system provided by the embodiments of the present application is shown in the figure;

[0046] Figure 7 A flowchart of another control method of a multi-split air conditioning system provided by the embodiments of the present application is shown in the figure;

[0047] Figure 8 A flowchart of another control method of a multi-split air conditioning system provided by the embodiments of the present application is shown in the figure;

[0048] Figure 9Another flowchart of a control method of a multi-split air conditioning system according to an embodiment of the present application is shown in FIG. 6.

[0049] Figure 10 Another flowchart of a control method of a multi-split air conditioning system according to an embodiment of the present application is shown in FIG. 6.

[0050] Figure 11 Another flowchart of a control method of a multi-split air conditioning system according to an embodiment of the present application is shown in FIG. 6.

[0051] Figure 12 Another flowchart of a control method of a multi-split air conditioning system according to an embodiment of the present application is shown in FIG. 6. DETAILED DESCRIPTION

[0052] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0053] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0054] The terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "multiple" is two or more.

[0055] In the description of the embodiments of the present application, it should be noted that, unless otherwise specified and limited, the terms "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. In addition, when describing the pipeline, "connected" and "connected" used in the present application have the meaning of conducting. The specific meaning needs to be understood in combination with the context.

[0056] In the embodiments of the present application, the word "exemplary" or "for example" is used to mean serving as an example, instance, or illustration. Any embodiment or design described in the embodiments of the present application as "exemplary" or "for example" should not be construed as preferred or advantageous over other embodiments or designs. Rather, the word "exemplary" or "for example" is used to present concepts in a concrete manner.

[0057] The multi-split air conditioning system provided by the embodiments of the present application can be a modular multi-split air conditioner. The outdoor unit of the multi-split air conditioning system can be one or more than one, and the indoor unit can be two or more than two. The embodiments of the present application do not make any limitation in this regard.

[0058] To further describe the technical solutions of the embodiments of the present application, as shown in Figure 1 FIG. 1 is a structural diagram of a multi-split air conditioning system provided by the embodiments of the present application.

[0059] As shown in Figure 1 and Figure 3 The multi-split air conditioning system 11 includes at least one outdoor unit and multiple parallel indoor units.

[0060] The outdoor unit includes an outdoor heat exchanger 101, a compressor 102, a four-way reversing valve 103, an outdoor throttling device 104, and a gas-liquid separator 105.

[0061] The indoor unit includes an indoor heat exchanger 201 and an indoor throttling device 202.

[0062] In some embodiments, the refrigerant is discharged from the exhaust port of the compressor 102 in the outdoor unit, passes through the four-way reversing valve 103, the outdoor heat exchanger 101, the outdoor throttling device 104, and then flows through the indoor throttling device in each operating indoor unit, the indoor heat exchanger, the four-way reversing valve 103, the gas-liquid separator 105, and finally enters the suction port of the compressor 102 to complete the refrigeration cycle circuit.

[0063] The setting and functions of each component of the outdoor unit are described in detail as follows.

[0064] In some embodiments, one end of the outdoor heat exchanger 101 is connected to the compressor 102 through the four-way reversing valve 103, and the other end is connected to each indoor heat exchanger through a connecting pipe. The outdoor heat exchanger 101 is used for heat exchange between the refrigerant flowing in the heat transfer pipe of the outdoor heat exchanger 101 and outdoor air.

[0065] In some embodiments, the compressor 102 is arranged between each indoor heat exchanger and the outdoor heat exchanger 101, and is used to provide power for the refrigerant circulation. Taking the refrigeration cycle as an example, the compressor 102 delivers the compressed refrigerant to the outdoor heat exchanger 101 through the four-way reversing valve 103.

[0066] In some embodiments, the four ports of the four-way reversing valve 103 are connected to the discharge port of the compressor 102, the outdoor heat exchanger 101, the suction port of the compressor 102, and each indoor heat exchanger, respectively. The four-way reversing valve 103 is used to realize the mutual conversion between the cooling mode and the heating mode by changing the flow direction of the refrigerant in the system pipeline.

[0067] In some embodiments, the outdoor throttling device 104 is arranged between the outdoor heat exchanger 101 and each indoor heat exchanger, and has the effect of expanding the refrigerant flowing through the outdoor throttling device 104 to achieve pressure reduction, for adjusting the refrigerant flow in the refrigerant passage. Optionally, the outdoor throttling device 104 can be an electronic expansion valve. If the opening degree of the outdoor throttling device 104 is reduced, the flow path resistance of the refrigerant passing through the outdoor throttling device 104 is increased. If the opening degree of the outdoor throttling device 104 is increased, the flow path resistance of the refrigerant passing through the outdoor throttling device 104 is reduced. In this way, even if the states of other devices in the circuit remain unchanged, when the opening degree of the outdoor throttling device 104 changes, the refrigerant flow to the indoor heat exchanger 201 or the outdoor heat exchanger 101 will also change.

[0068] In some embodiments, the gas-liquid separator 105 is connected to the suction port of the compressor 102, and is used to accommodate the refrigerant of the liquid return part in the refrigerant passage, to prevent liquid impact on the compressor 102.

[0069] In some embodiments, as shown in FIG. 1, the outdoor unit of the multi-split air conditioning system further includes a bypass valve 106. Figure 2

[0070] In some embodiments, the bypass valve 106 is arranged between the discharge port of the compressor 102 and the suction port of the gas-liquid separator, and is used to, when the compressor discharge superheat or the suction superheat is too low, open the bypass valve 106 to increase the suction superheat of the compressor 102, thereby reducing the liquid return amount of the compressor 102. Optionally, the bypass valve 106 can be a high-low pressure bypass valve.

[0071] In some embodiments, the outdoor unit of the multi-split air conditioning system further includes a fan. The fan is arranged in the outdoor unit, and is used to generate air flow of the outdoor air near the outdoor heat exchanger, to promote the heat exchange between the refrigerant flowing in the heat transfer pipe of the outdoor heat exchanger and the outdoor air.

[0072] Optionally, the outdoor unit further includes an outdoor fan motor, which is connected to the outdoor fan, and is used to drive or change the rotating speed of the outdoor fan.

[0073] The arrangement and functions of each component of the indoor unit are described below.

[0074] ​In some embodiments, the indoor heat exchanger 201 is used to perform heat exchange between the refrigerant flowing in the heat transfer tube of the indoor heat exchanger 201 and the indoor air.

[0075] In some embodiments, the indoor throttling device 202 is connected to the indoor heat exchanger 201 and is used to expand the refrigerant flowing through the indoor throttling device 202 to achieve a pressure reduction effect, thereby regulating the refrigerant flow rate in the refrigerant passage. Optionally, the indoor throttling device 202 can be an electronic expansion valve.

[0076] like Figure 4 As shown, the multi-split air conditioning system further includes a controller 300. The controller 300 is electrically connected to the outdoor heat exchanger 101, the compressor 102, the four-way reversing valve 103, the outdoor throttling device 104, the gas-liquid separator 105, the bypass valve 106, the indoor heat exchanger 201 and the indoor throttling device 202.

[0077] In some embodiments, the controller 300 is a device that can generate an operation control signal based on an instruction opcode and a timing signal to instruct the air conditioning system to execute the control instruction. For example, the controller 300 can be a central processing unit (CPU), a general-purpose processor, a network processor (NP), a digital signal processor (DSP), a microprocessor, a microcontroller, a programmable logic device (PLD), or any combination thereof. The controller 300 can also be other devices with processing functions, such as circuits, devices, or software modules, and the embodiments of the present application do not impose any restrictions on this.

[0078] In addition, the controller 300 can be used to control the operation of each component in the multi-split air-conditioning system 11, so that each component of the multi-split air-conditioning system 11 can operate to achieve various predetermined functions of the air-conditioning system.

[0079] In some embodiments, the controller 300 includes an outdoor control module and an indoor control module. The outdoor control module includes a first memory, and the indoor control module includes a second memory. The indoor control module is connected to the outdoor control module via wired or wireless communication. The outdoor control module can be installed in the outdoor unit or independently of the outdoor unit to control the outdoor unit to perform related operations. The indoor control module can be installed in the indoor unit or independently of the indoor unit to control the components of the indoor unit. It should be understood that the above module division is only a functional division, and the outdoor control module and the indoor control module can also be integrated into one module. The first memory and the second memory can also be integrated into one memory.

[0080] In some embodiments, the first memory is configured to store application programs and data related to the outdoor unit, and the outdoor control module executes various functions of the air conditioning system and data processing by running the application programs and data stored in the memory. The first memory mainly includes a program storage area and a data storage area. The program storage area can store an operating system and at least one application program required for a function (such as a regulation program of each throttling device). The data storage area can store data created according to the use of the multi-split air conditioning system (such as the opening degree of each throttling device). In addition, the first memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0081] In some embodiments, the second memory is configured to store application programs and data related to a plurality of indoor units and each indoor unit throttling device, and the indoor control module executes various functions of the multi-split air conditioning system and data processing by running the application programs and data stored in the memory. The second memory mainly includes a program storage area and a data storage area. The program storage area can store an operating system and at least one application program required for a function (such as a regulation program of each throttling device). The data storage area can store data created according to the use of the multi-split air conditioning system (such as the opening degree of each throttling device). In some examples, the second memory is also configured to store the correspondence between the address of the indoor unit and the address of each throttling device.

[0082] In some embodiments, the outdoor control module and the outdoor unit are in communication connection, for controlling the outdoor unit to perform related operations according to user instructions or system default instructions. Optionally, the outdoor control module can control the opening degree of each throttling device according to the compressor discharge superheat. Optionally, the outdoor control module can also obtain the outdoor temperature according to user instructions or system instructions, and store the obtained outdoor temperature to the first memory. Optionally, the outdoor control module can also control the rotation of the four-way reversing valve in the outdoor unit according to the air conditioning operation mode selected by the user, to realize the selection of the cooling or heating mode. Optionally, the outdoor control module can also control the operation mode, compressor frequency, etc. of the outdoor unit during the address correction process.

[0083] In some embodiments, the indoor control module and the indoor unit are in communication connection, for controlling the indoor unit to perform related operations according to user instructions or system default instructions. Optionally, the indoor control module controls the opening degree of each throttling device according to the compressor discharge superheat. Optionally, the indoor control module can also detect the indoor temperature according to user instructions.

[0084] The problems existing in the operation process of the multi-split air conditioning system in the related art and the control method of the multi-split air conditioning system provided by the embodiments of the present application will be described below with reference to the accompanying drawings.

[0085] In the related art, when the number of indoor units operating in the refrigeration mode increases, the operating frequency of the compressor also increases to output more refrigeration capacity as the refrigeration load of the multi-split air conditioning system increases. At this time, the throttling device of the operating indoor unit calculates the initial opening degree according to the load, and automatically adjusts the target superheat degree of the indoor unit on this basis. When the indoor and outdoor environment temperatures are low, the refrigeration load of the operating indoor unit increases significantly, and the compressor frequency required by the multi-split air conditioning system increases. During the transition period when the number of operating indoor units increases, a large amount of refrigerant still exists in the outdoor unit and the connecting pipe. Because the opening degree of the throttling device of the operating indoor unit is small, the refrigerant flow rate on the suction side is small, and as the operating frequency increases, the suction pressure is low, which in turn causes the superheat degree of the indoor unit to be high. To this end, the opening degree of the throttling device of the operating indoor unit is continuously increased. However, after a large amount of liquid refrigerant circulates from the outdoor heat exchanger to the operating indoor unit, because the opening degree of the throttling device of the operating indoor unit has been increased to a certain opening degree, the flow rate of the liquid refrigerant is large, and the operating indoor unit evaporates incompletely, causing a large amount of liquid refrigerant to return to the gas-liquid separator of the outdoor unit from the operating indoor unit, causing the liquid level of the gas-liquid separator to rise rapidly.

[0086] Therefore, the embodiments of the present application provide a control method of a multi-split air conditioning system, which is applied to a controller of the multi-split air conditioning system. As shown in the method comprises the following steps: Figure 5

[0087] S101, in response to the number of operating indoor units of the multi-split air conditioning system operating in the refrigeration mode being increased, adjusting the opening degree of the indoor throttling device of the operating indoor unit to an initial opening degree.

[0088] Wherein, the operating indoor unit is the indoor unit that is started to operate.

[0089] In some embodiments, the initial opening degree EVI(n) of the nth operating indoor unit satisfies the following relationship:

[0090] EVI(n) = EVI_ON x HP / HP_ON

[0091] Wherein, EVI_ON is the total opening degree of the throttling device of the operating indoor unit, HP is the capacity of the nth operating indoor unit, and HP_ON is the total capacity of the operating indoor unit.

[0092] In some embodiments, the total opening degree EVI_ON of the throttling device of the operating indoor unit satisfies the following relationship:

[0093] EVI_ON = K1(HP_ON x Ta + k2) x Hz

[0094] ​Wherein, K1 and K2 are constants; Ta is the ambient temperature of the outdoor unit; Hz is the compressor operating frequency. Ta is in positive correlation with EVI(n); HP is in positive correlation with EVI(n).

[0095] In some embodiments, the compressor operating frequency Hz:

[0096] Hz=Ka×KHP_ON×Kc

[0097] Wherein, Ka is a constant, and optionally, the value range of Ka is 5-10; KHP_ON is the capacity coefficient of the operating indoor unit; Kc is the indoor unit cooling load coefficient. Kc is in positive correlation with KHP_ON.

[0098] It should be understood that when multiple compressors are in operation in the multi-split air conditioning system, the compressor operating frequency refers to the sum of the operating frequencies of each compressor in operation.

[0099] S102, within a first preset time period after increasing the number of operating indoor units, the opening degree of the indoor throttling device of the operating indoor unit is kept unchanged when a first preset condition is met.

[0100] Wherein, the first preset condition includes:

[0101] The outdoor ambient temperature is less than or equal to a first temperature;

[0102] The superheat degree of the operating indoor unit is less than or equal to a first superheat degree, and the first superheat degree is greater than a target superheat degree;

[0103] The compressor discharge superheat degree is less than or equal to a first discharge superheat degree;

[0104] And, the compressor suction pressure is greater than a minimum suction pressure.

[0105] For example, the first preset time period is 3-10 minutes; the first temperature is 25℃; the first superheat degree is 50℃; the target superheat degree is 0℃; and the first discharge superheat degree is 30℃.

[0106] In some embodiments, the minimum suction pressure of the compressor is in positive correlation with the ambient temperature of the outdoor unit.

[0107] It should be understood that in the above first preset condition, when the superheat degree of the operating indoor unit is less than or equal to the first superheat degree, it means that the indoor unit can still operate normally. In the above first preset condition, when the compressor discharge superheat degree is less than or equal to the first discharge superheat degree, and the compressor suction pressure is greater than the minimum suction pressure, it means that the compressor can still operate normally. In summary, when the first preset condition is met, it means that the multi-split air conditioning system can operate in the cooling mode normally at low outdoor temperature (i.e., the outdoor ambient temperature is less than or equal to the first temperature).

[0108] The embodiments of the present application bring at least the following beneficial effects: after the number of operating indoor units is increased, the opening degree adjustment mode taking the target superheat degree as the adjustment target is not adopted within the preset time period, and the opening degree of the indoor throttling device of the operating indoor unit is not adjusted in the case that the first preset condition is met (i.e., in the case that the multi-split air conditioning system can still operate normally when the outdoor ambient temperature is low), so as to avoid adjusting the opening degree of the indoor throttling device of the operating indoor unit too large within the preset time period, and further avoid causing the gas-liquid separator to produce liquid accumulation.

[0109] In some embodiments, with reference to Figure 6 The embodiments of the present application further provide a control method of a multi-split air conditioning system, which comprises the following steps:

[0110] S201, in response to the number of operating indoor units of the multi-split air conditioning system operating in a cooling mode being increased, adjusting the opening degree of the indoor throttling device of the operating indoor unit to an initial opening degree.

[0111] The determination manner of the initial opening degree of the operating indoor unit can be implemented by referring to the description in the above step S101, and will not be described here.

[0112] S202, within a first preset time period after the number of operating indoor units is increased, reducing the opening degree of the indoor throttling device of the operating indoor unit in the case that a second preset condition is met.

[0113] The second preset condition comprises:

[0114] The outdoor ambient temperature is less than or equal to a first temperature;

[0115] The compressor discharge superheat degree is less than or equal to a second discharge superheat degree, and the second discharge superheat degree is less than the first discharge superheat degree;

[0116] The difference between the compressor discharge temperature of the current detection period and the compressor discharge temperature of the last detection period is less than or equal to a second temperature;

[0117] The superheat degree of the operating indoor unit is less than or equal to a second superheat degree, and the second superheat degree is less than the first superheat degree; and

[0118] The compressor suction pressure is greater than or equal to a minimum suction pressure.

[0119] For example, the second discharge superheat degree is 30℃, and the second temperature is 5℃.

[0120] It should be understood that the compressor discharge superheat is less than or equal to the second discharge superheat, the second discharge superheat is less than the first discharge superheat, and the difference between the compressor discharge temperature of the current detection period and the compressor discharge temperature of the last detection period is less than or equal to the second temperature, which indicates that the discharge superheat of the compressor is rapidly decreasing. Therefore, the application increases the discharge superheat by reducing the opening degree of the indoor throttling device when the second preset condition is met, so as to prevent the liquid refrigerant returning to the compressor from causing damage to the compressor.

[0121] It should be understood that the above Figure 5 The embodiments shown in Figure 6 The embodiments shown in

[0122] In some embodiments, after the first preset time period elapses, the controller is further configured to: based on the superheat of the operating indoor unit, adjust the opening degree of the indoor throttling device of the operating indoor unit, so that the superheat of the operating indoor unit is less than or equal to the target superheat.

[0123] In the related art, in a high-temperature refrigeration working condition, when the number of operating indoor units increases, the operating frequency of the compressor also increases to output more refrigeration capacity as the refrigeration load of the multi-split air conditioning system increases. At this time, the throttling device of the operating indoor unit calculates the initial opening degree according to the load, and automatically adjusts according to the target superheat of the indoor unit. When the ambient temperature of the operating indoor unit and outdoor unit is high, the refrigeration load of the indoor unit increases significantly, and the compressor frequency required by the multi-split air conditioning system increases. For a modular multi-split air conditioning system, the number of operating outdoor units and the number of compressors increase. During the transition period when the number of operating indoor units increases, a large amount of refrigerant still exists in the outdoor unit and the connecting pipe. Due to the small opening degree of the throttling device of the operating indoor unit, the suction side refrigerant flow is small, and due to the increase of the operating frequency, the suction pressure is low, and the superheat of the operating indoor unit is high. The multi-split air conditioning system continues to increase the opening degree of the throttling device of the operating indoor unit. However, due to the high ambient temperature of the outdoor unit, as the operating frequency of the multi-split air conditioning system increases, the exhaust pressure or exhaust temperature of a certain module increases rapidly, and the compressor frequency decreases rapidly after reaching the compressor protection value, and further, the number of operating outdoor units and the number of compressors decrease rapidly. Because the opening degree of the throttling device of the operating indoor unit is large and the compressor frequency is high before the frequency is reduced, the refrigerant circulation amount is large at this time, which causes incomplete evaporation of the operating indoor unit in a short time. At this time, part of the liquid refrigerant returns to the outdoor unit and enters the gas-liquid separator for storage. However, the amount of refrigerant that should be stored in multiple gas-liquid separators enters a small number of or even a single gas-liquid separator of the operating outdoor unit, and the volume of the gas-liquid separator is small and insufficient to store all the liquid refrigerant, which causes the amount of refrigerant in the gas-liquid separator of the operating indoor unit to increase rapidly and even cause the risk of full liquid.

[0124] Therefore, the embodiment of the present application further provides a control method of a multi-split air conditioning system. As shown in the figure, the method comprises the following steps: Figure 7

[0125] S301, in response to the multi-split air conditioning system running in a cooling mode, increasing the number of running indoor units, and adjusting the opening degree of the indoor throttling device of the running indoor unit to an initial opening degree.

[0126] The determination method of the initial opening degree of the running indoor unit can be achieved by referring to the description in the above step S101, which will not be described here.

[0127] S302, within a first preset time period after increasing the number of running indoor units, reducing the opening degree of the indoor throttling device of the running indoor unit under the condition that a third preset condition is met.

[0128] The third preset condition comprises:

[0129] The outdoor environment temperature is greater than a third temperature, and the third temperature is greater than the first temperature;

[0130] The multi-split air conditioning system reduces the number of compressors in a running state;

[0131] The suction pressure of the compressor is greater than or equal to a minimum suction pressure;

[0132] The discharge pressure of the compressor is less than or equal to a maximum discharge pressure; and

[0133] The discharge temperature of the compressor is less than a fourth temperature.

[0134] For example, the third temperature is 30℃, and the fourth temperature is 120℃.

[0135] In some embodiments, the opening degree of the throttling device of the adjusted nth running indoor unit satisfies the following formula:

[0136] EVI(n)' = EVI(n)' - {EVI_ON' - EVI_ON} x HP / HP_ON

[0137] Wherein, EVI(n)' is the opening degree of the throttling device of the nth running indoor unit in the previous cycle, EVI_ON' is the total opening degree of the throttling device of the running indoor unit in the previous cycle, EVI_ON is the total opening degree of the throttling device of the running indoor unit in the current cycle, HP is the capacity of the nth running indoor unit, and HP_ON is the total capacity of the running indoor unit.

[0138] In some embodiments, EVI_ON satisfies the following relationship:

[0139] EVI_ON = K1(HP_ON x Ta + k2) x Hz(n)​

[0140] wherein, K1 and K2 are constants; Ta is the ambient temperature of the outdoor unit; Hz(n) is the current cycle compressor operating frequency. Ta is in a positive correlation with EVI(n); HP is in a positive correlation with EVI(n).

[0141] It should be understood that the outdoor ambient temperature greater than the third temperature indicates that the multi-split air conditioning system is in a high-temperature refrigeration working condition. Due to the high indoor ambient temperature, as the operating frequency of the multi-split air conditioning system increases, the discharge pressure or the discharge temperature of some outdoor units reaches the protection value, and the compressor is turned off. However, as the number of operating indoor units increases, the amount of refrigerant required also increases, resulting in a large amount of refrigerant concentrated in the operating outdoor unit, and further resulting in an excessive amount of refrigerant in the gas-liquid separator in the operating outdoor unit. In the prior art, increasing the opening degree of the indoor throttling device according to the target superheat degree leads to incomplete evaporation of the indoor unit, and a large amount of liquid refrigerant returns to the gas-liquid separator in the outdoor unit, resulting in the problem of liquid accumulation in the gas-liquid separator. To prevent the above situation from occurring, the present application reduces the opening degree of the indoor throttling device of the operating indoor unit under the condition that the third preset condition is met (i.e., in the case that the number of compressors is reduced, but the multi-split air conditioning system continues to operate normally), to prevent the gas-liquid separator in the operating outdoor unit from storing a large amount of liquid and further causing damage to the compressor.

[0142] In some embodiments, after the first preset time period, the controller is further configured to adjust the opening degree of the indoor throttling device of the operating indoor unit based on the superheat degree of the operating indoor unit, so that the superheat degree of the operating indoor unit is less than or equal to the target superheat degree.

[0143] In the related art, the multi-split air conditioning system has the following problems: in a low-temperature refrigeration working condition, the outdoor ambient temperature is low, and the indoor ambient temperature is high. In this environment, if the sleep time of the multi-split air conditioning system is long, that is, the multi-split air conditioning system has not been running for a long time, a large amount of liquid refrigerant is stored in the outdoor heat exchanger, the gas-liquid separator and the connecting pipe due to the high indoor pressure and the low outdoor pressure. In this working condition, during the sleep start process of the multi-split air conditioning system, since the parameters are not stable in the initial stage of start, the multi-split air conditioning system cannot determine the distribution of the refrigerant through the operating parameters, and it is easy to cause the opening degree of the throttling device of the operating indoor unit to be too large in a short time. Moreover, at this time, there is a large amount of liquid refrigerant on the outdoor side, and the operating indoor unit evaporates incompletely, resulting in a large amount of refrigerant returning to the gas-liquid separator in the outdoor unit from the operating indoor unit, and causing the liquid level of the gas-liquid separator to rise rapidly.

[0144] Therefore, the embodiments of the present application also provide a control method of a multi-split air conditioning system. As shown in Figure 8 the method comprises the following steps:

[0145] S401、responding to the instruction indicating that the multi-connected air conditioning system starts the cooling mode, obtaining the capacity of each operating indoor unit, and calculating a first total opening degree based on the capacity of each operating indoor unit.

[0146] In some embodiments, the first total opening degree EVI_ON satisfies the following relationship:

[0147] EVI_ON=K1(HP_ON×Ta+k2)×Hz

[0148] wherein K1 and K2 are constants; Ta is the ambient temperature of the outdoor unit; Hz is the operating frequency of the compressor. Ta is positively correlated with EVI(n); HP is positively correlated with EVI(n).

[0149] In some embodiments, the operating frequency of the compressor Hz is:

[0150] Hz=Ka×KHP_ON×Kc

[0151] wherein Ka is a constant, and optionally, Ka has a value range of 5-10; KHP_ON is the capacity coefficient of the operating indoor unit; Kc is the cooling load coefficient of the indoor unit. Kc is positively correlated with KHP_ON.

[0152] S402, obtaining the capacity of each operating outdoor heat exchanger, and calculating a second total opening degree based on the capacity of each operating outdoor heat exchanger.

[0153] In some embodiments, the second total opening degree EVI_ONmax satisfies the following relationship:

[0154] EVI_ONmax=(K3×HP_W+K4)×KTa

[0155] wherein K3 and K4 are constants; HP_W is the total capacity of the operating outdoor unit; KTa is the temperature coefficient, and the greater the outdoor ambient temperature Ta, the greater the KTa.

[0156] S403, selecting the minimum value from the first total opening degree and the second total opening degree as a target total opening degree.

[0157] S404, based on the target total opening degree and the capacity of each operating indoor unit, calculating the initial opening degree of the indoor throttling device of each operating indoor unit.

[0158] As a possible implementation, when the target total opening degree is the first total opening degree, the initial opening degree EVI(n) of the indoor throttling device of the nth operating indoor unit is determined by the following formula:

[0159] EVI(n)=EVI_ON×HP / HP_ON

[0160] wherein EVI_ON is the total opening degree of the throttling device of the running indoor unit, HP is the capacity of the nth running indoor unit, and HP_ON is the total capacity of the running indoor units.

[0161] As another possible implementation, when the target total opening degree is the second total opening degree, the initial opening degree EVI(n) of the indoor throttling device of the nth running indoor unit is determined by using the following formula:

[0162] EVI(n) = EVI_ONmax x HP / HP_ON

[0163] S405, based on the initial opening degree of the indoor throttling device of each running indoor unit, adjusting the opening degree of the indoor throttling device of each running indoor unit.

[0164] It should be understood that the total opening degree of the indoor throttling device derived from the total capacity of the running indoor units and the total opening degree of the indoor throttling device derived from the total capacity of the running outdoor heat exchangers can be different. Therefore, the initial opening degree of the throttling device of each running indoor unit can be calculated by taking the minimum value of the two as the target total opening degree, and the opening degree of the throttling device of the running indoor unit is adjusted based on the initial opening degree, which can prevent the opening degree of the throttling device of the running indoor unit from being too large to cause more liquid accumulation in the gas-liquid separator.

[0165] In some embodiments, as shown in Figure 9 , step S405 can be specifically implemented as the following steps:

[0166] S4051, when the initial opening degree of the indoor throttling device of the running indoor unit is greater than or equal to the preset minimum opening degree and less than or equal to the preset maximum opening degree, adjusting the opening degree of the indoor throttling device of the running indoor unit to the corresponding initial opening degree.

[0167] S4052, when the initial opening degree of the indoor throttling device of the running indoor unit is greater than the preset maximum opening degree, adjusting the opening degree of the indoor throttling device of the running indoor unit to the preset maximum opening degree.

[0168] S4053, when the initial opening degree of the indoor throttling device of the running indoor unit is less than the preset minimum opening degree, adjusting the opening degree of the indoor throttling device of the running indoor unit to the preset minimum opening degree.

[0169] It should be understood that by limiting the upper and lower limits of the initial opening degree, the opening degree of the indoor throttling device of the running indoor unit is prevented from being adjusted too large or too small, thereby ensuring the normal operation of the multi-split air conditioning system.

[0170] In some embodiments, as shown in Figure 8 , the embodiments of the present application provide a control method of a multi-split air conditioning system, and the method further comprises the following steps:

[0171] S406、in the second preset time period after the multi-split air conditioning system starts the refrigeration mode, the opening degree of the indoor throttling device of the operating indoor unit is reduced when the fourth preset condition or the fifth preset condition is met.

[0172] The fourth preset condition comprises: the compressor discharge superheat is less than or equal to the second discharge superheat, and the superheat of the operating indoor unit is less than or equal to the third superheat.

[0173] The fifth preset condition comprises: the compressor discharge superheat is less than or equal to the third discharge superheat, the compressor suction pressure is greater than the minimum suction pressure, and the outdoor environment temperature is less than or equal to the first temperature, and the third discharge superheat is less than the second discharge superheat.

[0174] For example, the second preset time period is 3-10 minutes, and the third discharge superheat is 10℃.

[0175] It should be understood that in the related art, when the compressor superheat is greater than the target superheat, the opening degree of the indoor throttling device is increased, but this may cause the gas-liquid separator to have excessive liquid due to the excessive opening degree of the indoor throttling device. In this application, the opening degree of the indoor throttling device of the operating indoor unit is reduced when the fourth preset condition or the fifth preset condition is met, so as to correct the opening degree of the indoor throttling device of the operating indoor unit while ensuring the reliability of the compressor. Although the superheat of the compressor exceeds the control target in the above process, the excessive liquid in the gas-liquid separator caused by the excessive opening degree of the indoor throttling device is avoided, thereby preventing damage to the compressor.

[0176] In some embodiments, in the second preset time period after the multi-split air conditioning system starts the refrigeration mode, the reduction of the opening degree EVI(n) of the indoor throttling device of the nth operating indoor unit meets the following relationship when the fourth preset condition or the fifth preset condition is met:

[0177] EVI(n) = EVI(n)' - 20

[0178] Wherein, EVI(n)' is the opening degree of the indoor throttling device of the nth operating indoor unit in the previous cycle.

[0179] In some embodiments, as shown in Figure 10 The application also provides a control method of a multi-split air conditioning system, which comprises the following steps:

[0180] S501, determining the operating frequency of the compressor according to the capacity of each operating indoor unit.

[0181] The operating frequency of the compressor and the capacity of each operating indoor unit have a positive correlation.

[0182] As another possible implementation, the operating frequency Hz of the compressor is determined using the following formula:

[0183] Hz = KHz x HP ON x KTa

[0184] wherein KHz is a frequency coefficient, and an exemplary value of KHz is in the range of 5-10;

[0185] As a possible implementation, the temperature coefficient KTa is determined using the following formula:

[0186] KTa = 0.05 * (Ta - 27) + 1

[0187] wherein 0.5 ≤ KTa ≤ 2.

[0188] S502, within a first preset time period after the number of operating indoor units is increased, the variation of the operating frequency of the compressor in operation is less than or equal to a preset frequency variation.

[0189] Exemplarily, the preset frequency variation is 50.

[0190] It should be understood that, before the number of indoor units is increased, the operating frequency of the compressor is related to the capacity of the operating indoor units. When the number of operating indoor units is increased, the capacity of the operating indoor units is increased, the target frequency of the compressor is also increased, and the circulation amount of the refrigerant is also rapidly increased. At this time, the frequency of the compressor is controlled to avoid the situation that the rapid increase of the circulation amount of the refrigerant causes excessive liquid accumulation in the gas-liquid separator.

[0191] In some embodiments, as shown in Figure 11 The application embodiments also provide a control method of a multi-split air conditioning system, which comprises the following steps:

[0192] S601, when the multi-split air conditioning system operates in a cooling mode and the outdoor environment temperature is less than or equal to a first temperature, if a sixth preset condition is met, the bypass valve is controlled to be opened.

[0193] wherein the sixth preset condition comprises at least one of the following: the compressor discharge superheat is less than a fourth discharge superheat; and the compressor suction superheat is less than a first suction superheat.

[0194] Exemplarily, the fourth discharge superheat is 0-15℃, and the first suction superheat is 0-5℃.

[0195] S602, after the bypass valve is opened, if a seventh preset condition is met, the bypass valve is controlled to be closed.

[0196] The seventh preset condition comprises at least one of the following: the opening duration of the bypass valve reaches a third preset duration; the compressor exhaust gas superheat is greater than or equal to a fifth exhaust gas superheat; and the compressor suction gas superheat is greater than or equal to a second suction gas superheat.

[0197] For example, the third preset duration is 2-10 minutes; the fifth exhaust gas superheat is 20-40℃; and the second suction gas superheat is 3-10℃.

[0198] It should be understood that when the multi-split air conditioning system operates in the low-temperature refrigeration condition, if the exhaust gas superheat or the suction gas superheat of the compressor is too low, the compressor may have a liquid return. In this case, the bypass valve needs to be opened to increase the suction gas superheat of the compressor and reduce the liquid return amount of the compressor. After the bypass valve is opened for a period of time and the exhaust gas superheat and the suction gas superheat of the compressor reach a reasonable range, the bypass valve can be closed to prevent the exhaust gas superheat or the suction gas superheat of the compressor from being too high and damaging the compressor.

[0199] In some embodiments, the control method of the multi-split air conditioning system further comprises reducing the rotating speed of the fan in the outdoor unit to reduce the condensation heat of the condenser in the sleep start process of the multi-split air conditioning system, so as to reduce the flow of the liquid refrigerant returning to the gas-liquid separator.

[0200] As a possible implementation, the rotating speed of the fan is determined by using the following formula:

[0201] Fan=KF×Hz×(Ta+5)

[0202] Wherein, KF is the fan coefficient.

[0203] In this way, when the multi-split air conditioning system operates in the low-temperature refrigeration condition, if the exhaust gas superheat or the suction gas superheat of the compressor is low, i.e., the compressor may have a liquid return, the bypass valve is controlled to be opened. By opening the bypass valve, the suction gas superheat of the compressor is increased, the liquid return amount of the compressor is reduced, and the reliability of the compressor is improved.

[0204] It can be seen that the above mainly introduces the scheme provided by the embodiments of the present application from the perspective of method. To implement the above functions, the embodiments of the present application provide corresponding hardware structures and / or software modules for executing various functions. Those skilled in the art should easily realize that, in combination with the modules and algorithm steps of the examples described in the embodiments disclosed herein, the embodiments of the present application can be realized in the form of hardware or a combination of hardware and computer software. Whether a certain function is executed by hardware or computer software driven hardware depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods for each specific application to implement the described functions, but such implementation should not be considered beyond the scope of the present application.

[0205] The embodiments of the present application can divide the functional modules of the controller according to the above method examples. For example, each functional module can be divided according to each function, or two or more functions can be integrated in one processing module. The above integrated module can be realized in the form of hardware or in the form of a software functional module. Optionally, the division of the modules in the embodiments of the present application is illustrative, and is only a logical functional division. In actual implementation, another division mode can be used.

[0206] The embodiments of the present application also provide a hardware structure diagram of a controller, as shown in the figure. Figure 12 The controller 300 further includes a processor 301, and optionally further includes a memory 302 and a communication interface 303 connected with the processor 301. The processor 301, the memory 302 and the communication interface 303 are connected through a bus 304.

[0207] The processor 301 can be a central processing unit (CPU), a general processor network processor (NP), a digital signal processing (DSP), a microprocessor, a microcontroller, a programmable logic device (PLD) or any combination thereof. The processor 301 can also be any other device having a processing function, such as a circuit, a device or a software module. The processor 301 can also include multiple CPUs, and the processor 301 can be a single-CPU processor or a multi-CPU processor. The processor herein can refer to one or more devices, circuits or processing cores for processing data (for example, computer program instructions).

[0208] The memory 302 can be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a random access memory (RAM) or other type of dynamic storage device that can store information and instructions, an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disk storage, a magnetic disk storage or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and that can be accessed by a computer, and the embodiments of the present application do not make any limitation thereon. The memory 302 can exist independently or be integrated with the processor 301. The memory 302 can contain computer program code. The processor 301 is configured to execute the computer program code stored in the memory 302, thereby implementing the control method provided by the embodiments of the present application.

[0209] The communication interface 303 can be configured to communicate with other devices or communication networks (such as Ethernet, a radio access network (RAN), a wireless local area network (WLAN), etc.). The communication interface 303 can be a module, a circuit, a transceiver, or any device capable of realizing communication.

[0210] The bus 304 can be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. The bus 304 can be divided into an address bus, a data bus, a control bus, etc. For the convenience of representation, Figure 12 Only one thick line is used in the figure, but it does not mean that there is only one bus or only one type of bus.

[0211] The embodiments of the present application also provide a computer readable storage medium, including computer execution instructions, when running on a computer, causing the computer to execute any one of the control methods of the air conditioning system provided by the above embodiments.

[0212] The embodiment of the present application further provides a computer program product comprising computer-executable instructions which, when executed on a computer, cause the computer to perform the control method of any of the air conditioning systems provided by the above-described embodiments.

[0213] In the above-described embodiments, the implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented by using a software program, the implementation can be achieved entirely or partially in the form of a computer program product. The computer program product includes one or more computer-executable instructions. When the computer-executable instructions are loaded and executed on a computer, the entire or partial process or function according to the embodiments of the present application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable apparatus. The computer-executable instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer-executable instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center through a wired (for example, coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (for example, infrared, wireless, microwave, etc.) manner. The computer-readable storage medium can be any available medium accessible by a computer or a data storage device including one or more servers, data centers, etc. integrated with the medium. The available medium can be a magnetic medium (for example, floppy disk, hard disk, magnetic tape), an optical medium (for example, DVD), or a semiconductor medium (for example, solid state disk (SSD)), etc.

[0214] Although the present application is described herein in conjunction with various embodiments, those skilled in the art, with the benefit of the drawings, the disclosure, and the appended claims, can understand and implement other variations of the disclosed embodiments in the implementation of the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit can implement several of the functions listed in the claims. Measures recited in mutually different dependent claims do not preclude their combination in a single claim.

[0215] Although the present application has been described in connection with certain specific features and embodiments thereof, it is to be understood that it is not to be limited to the features and embodiments specifically described, but rather can be practiced with modification and alteration, which can be apparent to those skilled in the art having the benefit of this disclosure. Accordingly, it is intended to embrace all such alterations, modifications, and variations that fall within the scope of the present application. It is intended that the application be construed as including all such alterations and modifications to the full extent that they come within the scope of the application's disclosure and the following claims and that no single feature or combination of features is essential to the practice of the application unless the disclosure explicitly states otherwise. It is intended to include equivalents of what is claimed and described herein.

[0216] The above description is only specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any change or replacement within the technical scope disclosed in the present application should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A multi-split air conditioning system, characterized in that, include: at least one outdoor unit, each outdoor unit comprising a compressor, an outdoor heat exchanger, and a gas-liquid separator; A plurality of indoor units, each indoor unit including an indoor heat exchanger and an indoor throttling device; A controller configured to: In response to the multi-split air conditioning system operating in a cooling mode increasing the number of operating indoor units, adjusting the openings of the indoor throttling devices of the operating indoor units to an initial opening; within a first preset time period after the number of the operating indoor units is increased, and under the condition that a first preset condition is satisfied, maintaining the opening of the indoor throttling device of the operating indoor unit unchanged; The first preset condition includes: The outdoor ambient temperature is less than or equal to the first temperature; The superheat degree of the operating indoor unit is less than or equal to a first superheat degree, and the first superheat degree is greater than a target superheat degree; The compressor discharge superheat is less than or equal to the first discharge superheat; and The compressor suction pressure is greater than or equal to the minimum suction pressure.

2. The multi-split air conditioning system according to claim 1, characterized in that: The controller is further configured to: Within a first preset time period after the number of operating indoor units is increased, if a second preset condition is met, reducing the opening of the indoor throttling device of the operating indoor unit; The second preset condition includes: The outdoor ambient temperature is less than or equal to the first temperature; The compressor exhaust superheat is less than or equal to a second exhaust superheat, and the second exhaust superheat is less than the first exhaust superheat; The difference between the compressor exhaust temperature in the current detection cycle and the compressor exhaust temperature in the previous detection cycle is less than or equal to the second temperature; The superheat degree of the operating indoor unit is less than or equal to a second superheat degree, and the second superheat degree is less than the first superheat degree; and The compressor suction pressure is greater than or equal to the minimum suction pressure.

3. The multi-split air conditioning system according to claim 1, characterized in that: The controller is further configured to: Within a first preset time period after the number of operating indoor units is increased, if a third preset condition is met, reducing the opening of the indoor throttling device of the operating indoor unit; The third preset condition includes: The outdoor ambient temperature is greater than a third temperature, and the third temperature is greater than the first temperature; The multi-split air conditioning system reduces the number of compressors in operation; The suction pressure of the compressor is greater than or equal to the minimum suction pressure; The compressor exhaust pressure is less than or equal to the maximum exhaust pressure; and The compressor exhaust temperature is lower than a fourth temperature.

4. The multi-split air conditioning system according to claim 1, characterized in that: The controller is further configured to: In response to an instruction instructing the multi-split air conditioning system to start a cooling mode, obtaining the capacity of each operating indoor unit and calculating a first total opening degree based on the capacity of each operating indoor unit; Obtaining the capacity of each outdoor heat exchanger that is started and operating, and calculating a second total opening degree based on the capacity of each outdoor heat exchanger that is started and operating; selecting a minimum value from the first total opening and the second total opening as a target total opening; The controller is further configured to calculate an initial opening degree of the indoor throttling device of each operating indoor unit based on the target total opening degree and the capacity of each operating indoor unit. The controller is further configured to adjust the opening degree of the indoor throttling device of each operating indoor unit based on the initial opening degree of the indoor throttling device of each operating indoor unit. 5.The multi-split air conditioning system of claim 4, wherein the controller is further configured to adjust the opening degree of the indoor throttling device of each operating indoor unit based on the initial opening degree of the indoor throttling device of each operating indoor unit, and specifically perform the following steps: when the initial opening degree of the indoor throttling device of the operating indoor unit is greater than or equal to a preset minimum opening degree and less than or equal to a preset maximum opening degree, adjust the opening degree of the indoor throttling device of the operating indoor unit to the corresponding initial opening degree; or, when the initial opening degree of the indoor throttling device of the operating indoor unit is greater than the preset maximum opening degree, adjust the opening degree of the indoor throttling device of the operating indoor unit to the preset maximum opening degree; or, when the initial opening degree of the indoor throttling device of the operating indoor unit is less than the preset minimum opening degree, adjust the opening degree of the indoor throttling device of the operating indoor unit to the preset minimum opening degree. 6.The multi-split air conditioning system of claim 4, wherein the controller is further configured to: after the multi-split air conditioning system starts the cooling mode, within a second preset time period, reduce the opening degree of the indoor throttling device of the operating indoor unit if a fourth preset condition or a fifth preset condition is met; wherein the fourth preset condition comprises that the compressor discharge superheat is less than or equal to a second discharge superheat, and the operating indoor unit superheat is less than or equal to a third superheat; the fifth preset condition comprises that the compressor discharge superheat is less than or equal to a third discharge superheat, the compressor suction pressure is greater than a minimum suction pressure, and the outdoor environment temperature is less than or equal to a first temperature, and the third discharge superheat is less than the second discharge superheat. 7.The multi-split air conditioning system of claim 4, wherein the controller is further configured to: determine the operating frequency of the compressor according to the capacity of each operating indoor unit, and there is a positive correlation between the operating frequency of the compressor and the capacity of each operating indoor unit. 8.The multi-split air conditioning system of any one of claims 1 to 7, wherein the controller is further configured to: within a first preset time period after the number of operating indoor units is increased, control the change amount of the operating frequency of the compressor in the operating state to be less than or equal to a preset frequency change amount. The outdoor unit further comprises a bypass valve, one end of the bypass valve is connected to the discharge port of the compressor, and the other end of the bypass valve is connected to the suction port of the gas-liquid separator. The controller is further configured to: when the multi-split air conditioning system operates in the cooling mode and the outdoor environment temperature is less than or equal to a first temperature, control the bypass valve to open if a sixth preset condition is met; after the bypass valve is opened, control the bypass valve to close if a seventh preset condition is met.

9. The multi-split air conditioning system according to any one of claims 1 to 7, wherein, ​ ​ ​ ​ The sixth preset condition comprises: the compressor discharge superheat is less than a fourth discharge superheat, or the compressor suction superheat is less than a first suction superheat; The seventh preset condition comprises: The opening duration of the bypass valve reaches a third preset duration, The compressor discharge superheat is greater than or equal to a fifth discharge superheat, and The compressor suction superheat is greater than or equal to a second suction superheat.

10. A control method of a multi VRF system, characterized by, The method comprises: In response to increasing the number of operating indoor units of a multi-split air conditioning system operating in a cooling mode, adjusting the opening degree of the indoor throttling device of the operating indoor unit to an initial opening degree, the operating indoor unit being a startup operating indoor unit; Within a first preset duration after increasing the number of operating indoor units, keeping the opening degree of the indoor throttling device of the operating indoor unit unchanged in the case of satisfying a first preset condition; The first preset condition comprises: The outdoor ambient temperature is less than or equal to a first temperature; The superheat of the operating indoor unit is less than or equal to a first superheat, the first superheat being greater than a target superheat; The compressor discharge superheat is less than or equal to a first discharge superheat; and The compressor suction pressure is greater than or equal to a minimum suction pressure.

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