Control method and control device of multi-connected air conditioning system and multi-connected air conditioning system

Abstract

The present application relates to the technical field of multi-connected air conditioner, and provides a control method and control device of a multi-connected air conditioner system and the multi-connected air conditioner system, the control method of the multi-connected air conditioner system comprises: when the operation mode is a refrigeration mode, and the fluctuation frequency is greater than or equal to a preset frequency, and the fluctuation correlation state is a correlation state, a signal of controlling the operation frequency of the compressor to be a target frequency is sent; wherein the target frequency is lower than the current frequency, and the frequency difference is a preset frequency difference. When the multi-connected air conditioner system operates in the refrigeration mode, if the exhaust temperature of the compressor fluctuates multiple times within a first preset time length, and the temperature fluctuation is caused by the opening and closing of the liquid injection valve, the operation frequency of the compressor is controlled to decrease from the current frequency to the target frequency, at this time, the exhaust temperature is maintained between a first preset temperature and a second preset temperature, avoiding the frequent opening and closing of the liquid injection valve causing the outlet air temperature of the indoor unit to fluctuate, and improving the comfort of the user.

Description

Technical Field

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

[0002] When a multi-split air conditioning system is in operation, the compressor operating parameters must comply with the operating specifications to protect the system. Exceeding the operating limit may cause damage to the compressor, which in turn may lead to failure of the air conditioning system. Multi-split air conditioning systems implement a series of controls around compressor protection and constant system pressure to ensure that all operating pressure points are within a reasonable range. In related technologies, in order to maintain system stability, the air conditioning system's control can cause fluctuations in air outlet temperature, reducing user comfort. Summary of the Invention

[0003] The present invention aims to address at least one of the technical problems existing in the related art. To this end, the present invention proposes a control method for a multi-split air conditioning system. When the compressor's exhaust temperature fluctuates frequently, the method reduces the compressor's operating frequency to a target frequency, thereby lowering both the compressor's exhaust and intake temperatures. This reduces fluctuations in the indoor unit's air outlet temperature caused by frequent switching of the liquid injection valve, thereby improving the stability of the air outlet temperature.

[0004] The present invention also provides a control device for a multi-connected air-conditioning system.

[0005] The present invention also provides a multi-connected air-conditioning system.

[0006] According to a first aspect of an embodiment of the present invention, a control method for a multi-split air-conditioning system is provided, wherein a refrigerant circulation circuit of the multi-split air-conditioning system includes a liquid injection valve, and the control method includes:

[0007] Obtaining an operating mode of the multi-split air conditioning system, a number of fluctuations in the exhaust temperature of the compressor within a first preset time period, a current frequency of the compressor, and a number of openings and closings of the liquid injection valve within the first preset time period, and determining a fluctuation correlation state based on the fluctuation number, the opening and closing number, and a pre-acquired correlation relationship; wherein the fluctuation correlation state includes an uncorrelated state and a correlated state;

[0008] When the operating mode is the cooling mode, and the number of fluctuations is greater than or equal to the preset number, and the fluctuation association state is the related state, a signal is sent to control the operating frequency of the compressor to be the target frequency; wherein, the target frequency is lower than the current frequency, and the frequency difference is the preset frequency difference.

[0009] According to one embodiment of the present application, the number of fluctuations of the discharge temperature of the compressor within the first preset time length is obtained by the following steps:

[0010] The discharge temperature of the compressor is obtained, and the over-temperature time when the discharge temperature is greater than a first preset temperature obtained in advance and the low-temperature time when the discharge temperature is less than a second preset temperature obtained in advance are recorded;

[0011] When there is one over-temperature time and one low-temperature time between two adjacent recorded times, it is determined that there is one fluctuation;

[0012] The number of fluctuations is determined according to all recorded times within the first preset time length.

[0013] According to one embodiment of the present application, the step of determining the fluctuation correlation state according to the number of fluctuations, the number of opening and closing, and the correlation relationship obtained in advance specifically includes:

[0014] When the number of fluctuations is equal to the number of opening and closing, the fluctuation correlation state is a correlation state;

[0015] When the number of fluctuations is not equal to the number of opening and closing, the fluctuation correlation state is an irrelevant state.

[0016] According to one embodiment of the present application, the step of determining the fluctuation correlation state according to the number of fluctuations, the number of opening and closing, and the correlation relationship obtained in advance further includes:

[0017] The fluctuation termination time when the discharge temperature of the compressor completes one fluctuation is recorded, and the opening and closing termination time when the liquid injection valve completes one opening and closing is recorded;

[0018] When the number of fluctuations is equal to the number of opening and closing, and the fluctuation termination time and the opening and closing termination time appear alternately, the fluctuation correlation state is a correlation state;

[0019] When the number of fluctuations is not equal to the number of opening and closing, or the fluctuation termination time and the opening and closing termination time do not appear alternately, the fluctuation correlation state is an irrelevant state.

[0020] According to one embodiment of the present application, the multi-split air conditioning system includes a plurality of indoor units, and each evaporator inlet of the indoor units is provided with an indoor valve, and the step of sending a signal to control the running frequency of the compressor to be a target frequency further includes:

[0021] After the second preset time length, the number of fluctuations of the discharge temperature of the compressor within a third preset time length is obtained;

[0022] When the fluctuation frequency is greater than zero, the minimum opening degree of the plurality of indoor unit valves is adjusted to a first target opening degree, wherein the superheat of the evaporator of the corresponding indoor unit is reduced by a preset temperature at the first target opening degree.

[0023] According to one embodiment of the present application, the step of issuing a signal to adjust the minimum opening degree of the plurality of indoor unit valves to a first target opening degree further comprises:

[0024] After the fourth preset time period, the fluctuation frequency of the discharge temperature of the compressor within the first preset time period is obtained;

[0025] When the fluctuation frequency is greater than zero, the compressor is controlled to operate according to the fluctuation correlation state within the first preset time period.

[0026] According to one embodiment of the present application, the step of obtaining the fluctuation frequency of the discharge temperature of the compressor within the third preset time period further comprises:

[0027] When the fluctuation frequency is zero, the current outdoor environment temperature is obtained, and the temperature difference between the current outdoor temperature and the initial outdoor environment temperature obtained at startup is calculated;

[0028] When the temperature difference is less than or equal to a preset temperature threshold, a signal is issued to control the operating frequency of the compressor to return to a preset frequency, wherein the preset frequency is determined according to a pre-stored compressor operating logic.

[0029] According to one embodiment of the present application, when the fluctuation frequency is greater than zero, the control method further comprises:

[0030] The current wind speed of the indoor fan is obtained, and the current wind speed of the indoor fan is adjusted to a target wind speed, wherein the wind speed difference between the current wind speed and the target wind speed is positively correlated with the preset temperature.

[0031] According to the control device of the multi-split air conditioning system provided by the second aspect of the present application, comprising:

[0032] The obtaining module is configured to obtain the operating mode of the multi-split air conditioning system, the fluctuation frequency of the discharge temperature of the compressor within a first preset time period, the current frequency of the compressor, and the opening and closing frequency of the liquid injection valve within the first preset time period, and determine a fluctuation correlation state according to the fluctuation frequency, the opening and closing frequency, and a pre-obtained correlation relationship; wherein the fluctuation correlation state includes an unrelated state and a related state.

[0033] The signal sending module is configured to send a signal to control the operating frequency of the compressor to be a target frequency when the operating mode is the refrigeration mode, the fluctuation frequency is greater than or equal to the preset frequency, and the fluctuation correlation state is the correlation state; wherein the target frequency is lower than the current frequency, and the frequency difference is a preset frequency difference.

[0034] According to the third aspect of the present application, the multi-split air conditioning system comprises a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor executes the program to implement the steps of the control method of the multi-split air conditioning system according to the first aspect of the present application.

[0035] The one or more technical solutions in the present application have at least one of the following technical effects:

[0036] The control method of the multi-split air conditioning system according to the first aspect of the present application comprises: acquiring an operating mode of the multi-split air conditioning system, a fluctuation frequency of a discharge temperature of a compressor in a first preset time length, a current frequency of the compressor and an opening and closing frequency of a liquid injection valve in the first preset time length, and determining a fluctuation correlation state according to the fluctuation frequency, the opening and closing frequency and a pre-acquired correlation relationship; wherein the fluctuation correlation state comprises an irrelevant state and a relevant state; when the operating mode is the refrigeration mode, the fluctuation frequency is greater than or equal to a preset frequency, and the fluctuation correlation state is the relevant state, a signal is sent to control the operating frequency of the compressor to be a target frequency; wherein the target frequency is lower than the current frequency, and the frequency difference is a preset frequency difference. When the multi-split air conditioning system operates in the refrigeration mode, if the discharge temperature of the compressor fluctuates multiple times in the first preset time length, and the temperature fluctuation is caused by the opening and closing of the liquid injection valve, the operating frequency of the compressor is controlled to decrease from the current frequency to the target frequency, at this time, the discharge temperature and the suction temperature of the compressor are reduced, the discharge temperature can be maintained between the first preset temperature and the second preset temperature, the opening and closing of the liquid injection valve is avoided to cause the fluctuation of the outlet air temperature of the indoor unit, the stability of the outlet air temperature can be maintained, and the comfort of the user is improved. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the following will briefly introduce the drawings needed to be used in the embodiment or related art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0038] Figure 1 One of the flowcharts of the control method of the multi-split air conditioning system according to the embodiments of the present application;

[0039] Figure 2 Flowchart No. 2 of the control method of the multi-split air conditioning system according to an embodiment of the present application;

[0040] Figure 3 Schematic structural diagram of the control device of the multi-split air conditioning system according to an embodiment of the present application;

[0041] Figure 4 Schematic structural diagram of the multi-split air conditioning system according to an embodiment of the present application.

[0042] Reference signs:

[0043] 301, acquisition module; 302, signal sending module. DETAILED DESCRIPTION

[0044] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be clearly described below with reference to the drawings in 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 of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0045] In the description of the embodiments of the present application, it should be noted that the terms “center”, “longitudinal”, “transverse”, “upper”, “lower”, “front”, “rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer” and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply 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 embodiments of the present application. In addition, the terms “first”, “second”, “third” are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0046] In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms “connected” and “connected” should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0047] In the embodiments of the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature can be "above", "over" and "on" the second feature, which can be that the first feature is directly above or obliquely above the second feature, or only indicates that the first feature is higher in horizontal height than the second feature. The first feature can be "under", "below" and "underneath" the second feature, which can be that the first feature is directly below or obliquely below the second feature, or only indicates that the first feature is lower in horizontal height than the second feature.

[0048] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example" or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0049] The multi-connected air conditioning system will carry out a series of controls around the protection of the compressor and the constancy of the system pressure, to ensure that all operating pressure points are within a reasonable range. In the related art, in order to maintain the stability of the system operation, when the air conditioning system is regulated, it will cause the fluctuation of the outlet air temperature, which reduces the comfort of the user.

[0050] The multi-connected air conditioning system provided by the embodiments of the present application includes a plurality of indoor units or a plurality of outdoor units, the plurality of indoor units are connected in parallel, the plurality of outdoor units are connected in parallel, and then are connected through a total refrigerant pipe. The indoor unit includes an evaporator and an indoor fan, the outdoor unit includes a condenser and an outdoor fan, and the remaining components are the same as or adapted to be used with the components of other air conditioning systems. In order to make the refrigerant amount and the refrigerant state in the multi-connected air conditioning system meet the demand in normal work, the evaporator inlet of each indoor unit is further provided with an indoor unit valve, and the condenser inlet of each outdoor unit is further provided with an outdoor unit valve. The indoor unit valve and the outdoor unit valve can adjust the refrigerant flow of the refrigerant flowing to the downstream, and can control the superheat degree before and after the refrigerant heat exchange. Taking the evaporator as an example, in the case that the indoor fan speed is constant and the indoor environment temperature is stable, the heat exchanged between the indoor air and the evaporator per unit time is determined. If the opening degree of the indoor unit valve is increased, the refrigerant flow flowing into the evaporator per unit time is increased, and under the same heat exchange efficiency, the refrigerant temperature at the outlet of the evaporator changes little, and the suction temperature of the compressor is reduced.

[0051] Meanwhile, the multi-connected air conditioning system is also provided with a liquid injection valve on the refrigerant circulation loop, which can be opened and closed when the exhaust temperature changes. When the exhaust temperature of the compressor is greater than the first preset temperature, for example, greater than 90 degrees Celsius, the liquid injection valve is in an open state, at which time the suction temperature of the compressor is reduced, and the exhaust temperature is also reduced. After the liquid injection valve is opened for a certain period of time, the exhaust temperature is reduced until it is less than the second preset temperature, for example, less than 80 degrees Celsius, at which time the liquid injection valve is closed. With the closing of the liquid injection valve, the exhaust temperature begins to gradually increase again, and the liquid injection valve is opened again, resulting in periodic changes in the opening degree of the indoor unit valve, the indoor coil temperature of the evaporator, and the outlet air temperature of the indoor fan.

[0052] According to the control method of the multi-connected air conditioning system provided by the first aspect of the present application, the following steps are included:

[0053] The operating mode of the multi-connected air conditioning system, the fluctuation frequency of the exhaust temperature of the compressor within the first preset time, the current frequency of the compressor, and the opening and closing frequency of the liquid injection valve within the first preset time are obtained, and the fluctuation correlation state is determined according to the fluctuation frequency, the opening and closing frequency, and the pre-acquired correlation relationship; wherein the fluctuation correlation state includes an unrelated state and a related state.

[0054] When the operating mode is the cooling mode, and the fluctuation frequency is greater than or equal to the preset frequency, and the fluctuation correlation state is the related state, a signal is sent to control the operating frequency of the compressor to be the target frequency; wherein the target frequency is lower than the current frequency, and the frequency difference is the preset frequency difference.

[0055] It can be understood that when the multi-connected air conditioning system is operating in the cooling mode, and the outdoor environment temperature is higher than the high temperature threshold, the exhaust temperature of the compressor will be relatively high in order to improve the heat exchange efficiency of the air conditioning system. At this time, the fluctuation frequency of the exhaust temperature of the compressor within the first preset time is detected, for example, the fluctuation frequency of the exhaust temperature within 30 minutes is 4 times, and the preset frequency is 3 times, then the fluctuation of the exhaust temperature of the compressor is relatively frequent, which will cause the outlet air temperature of the indoor unit to fluctuate frequently, and it is necessary to further determine whether the fluctuation of the exhaust temperature and the opening and closing of the liquid injection valve are correlated.

[0056] The fluctuation correlation state is determined according to the fluctuation frequency of the exhaust temperature of the compressor within the first preset time, the opening and closing frequency of the liquid injection valve, and the pre-acquired correlation relationship. The pre-acquired correlation relationship is a program set in the storage module, which can determine the fluctuation correlation state according to the fluctuation frequency of the exhaust temperature of the compressor and the opening and closing frequency of the liquid injection valve, wherein the fluctuation correlation state includes an unrelated state and a related state.

[0057] If the fluctuation correlation state is the relevant state, it indicates that the fluctuation of the exhaust temperature is caused by the opening and closing action of the liquid injection valve, and at this time measures need to be taken to avoid the frequent opening and closing of the liquid injection valve; if the fluctuation correlation state is the irrelevant state, other reasons need to be found, and the phenomenon of exhaust temperature fluctuation is solved through other means.

[0058] When the operation mode is the refrigeration mode, the fluctuation frequency is greater than or equal to the preset frequency, and the fluctuation correlation state is the relevant state, a signal of controlling the operation frequency of the compressor to be the target frequency is sent; wherein the target frequency is lower than the current frequency, and the frequency difference is the preset frequency difference.

[0059] It can be understood that reducing the operation frequency of the compressor from the current frequency by the preset frequency difference to the target frequency can reduce the exhaust temperature of the compressor. In the case where the heat exchange efficiency does not change, the suction temperature of the compressor will also be reduced, thereby limiting the exhaust temperature of the compressor between the first preset temperature and the second preset temperature, for example, between 90 degrees Celsius and 80 degrees Celsius, corresponding to the opening temperature and the closing temperature of the liquid injection valve.

[0060] When the exhaust temperature of the compressor is between the first preset temperature and the second preset temperature, the liquid injection valve will not appear the frequent opening and closing, and therefore will not cause the exhaust temperature of the compressor to fluctuate, and at this time the outlet air temperature of the indoor unit can be kept stable.

[0061] Please refer to Figure 1 The control method of the multi-split air conditioning system provided by the embodiment of the application comprises the following processes:

[0062] S100, acquiring the operation mode of the multi-split air conditioning system, acquiring the fluctuation frequency of the exhaust temperature of the compressor within a first preset time length, acquiring the current frequency of the compressor, and acquiring the opening and closing frequency of the liquid injection valve within the first preset time length.

[0063] S110, determining whether the operation mode is the refrigeration mode and the fluctuation frequency is greater than or equal to the preset frequency.

[0064] If not, step S120 is executed; if yes, step S130 is executed.

[0065] S120, sending a signal of controlling the compressor to operate at the current frequency.

[0066] S130, determining the fluctuation correlation state according to the fluctuation frequency, the opening and closing frequency, and the pre-acquired correlation relationship.

[0067] S140, determining whether the fluctuation correlation state is the relevant state.

[0068] If not, step S150 is executed; if yes, step S160 is executed.

[0069] S150, issuing a signal to control the operating frequency of the compressor to be the current frequency.

[0070] S160, issuing a signal to control the operating frequency of the compressor to be the target frequency.

[0071] It should be noted that the above process is only one embodiment of the control method of the multi-split air conditioning system. Other similar processes can be executed in step S160 when the operating mode is the cooling mode, the fluctuation frequency is greater than or equal to the preset frequency, and the fluctuation correlation state is the correlation state, which also belongs to the technical concept of the embodiments of the present application.

[0072] In the embodiments of the present application, the suction temperature and the discharge temperature of the compressor are reduced to avoid frequent opening and closing of the liquid injection valve. The fluctuation frequency of the discharge temperature of the compressor within the first preset time is obtained by the following steps:

[0073] The discharge temperature of the compressor is obtained, and the over-temperature moment when the discharge temperature is greater than the first preset temperature and the low-temperature moment when the discharge temperature is less than the second preset temperature are recorded.

[0074] When there is an over-temperature moment and a low-temperature moment between two adjacent recorded moments, it is determined that there is a fluctuation.

[0075] The fluctuation frequency is determined according to all recorded moments within the first preset time.

[0076] It can be understood that the first preset temperature and the second preset temperature are pre-stored in the system, for example, 90 degrees Celsius and 80 degrees Celsius, which correspond to the opening temperature and the closing temperature of the liquid injection valve. When the discharge temperature fluctuates, it needs to experience a condition of being greater than the first preset temperature and a condition of being less than the second preset temperature.

[0077] When the discharge temperature is greater than the first preset temperature, the corresponding over-temperature moment is immediately recorded; when the discharge temperature is less than the second preset temperature, the corresponding low-temperature moment is immediately recorded. By the above method, multiple over-temperature moments and multiple low-temperature moments can be recorded. Only when the adjacent two recorded moments are over-temperature moment and low-temperature moment respectively, it is confirmed that a fluctuation is completed. At this time, the fluctuation of the outlet air temperature of the indoor unit is large, and the influence on the user is large.

[0078] Thereafter, all recorded moments within the first preset time are counted, and the fluctuation frequency within the first preset time can be obtained according to whether the adjacent two recorded moments meet the confirmation condition.

[0079] By the above method, the total fluctuation frequency of the discharge temperature of the compressor within the first preset time can be obtained, and the fluctuation of the outlet air temperature can be determined.

[0080] It should be noted that the first preset time length can be 10 minutes, 20 minutes or 30 minutes, etc., which is determined according to the actual situation. At the same time, the preset number of times will also change with the adjustment of the first preset time length, for example, fluctuating more than twice within 10 minutes, or more than four times within 30 minutes, which will be confirmed as frequent fluctuation.

[0081] In some embodiments, the step of determining the fluctuation correlation state according to the fluctuation number of times, the opening and closing number of times, and the pre-acquired correlation relationship specifically includes:

[0082] When the fluctuation number of times is equal to the opening and closing number of times, the fluctuation correlation state is a correlation state.

[0083] When the fluctuation number of times is not equal to the opening and closing number of times, the fluctuation correlation state is an irrelevant state.

[0084] It can be understood that, within the first preset time length, if the fluctuation number of times is equal to the opening and closing number of times, it means that the opening and closing of the liquid injection valve and the fluctuation of the exhaust temperature have a direct correlation, and the fluctuation correlation state is a correlation state. If the fluctuation number of times is not equal to the opening and closing number of times, it means that the opening and closing of the liquid injection valve and the fluctuation of the exhaust temperature do not have a direct correlation, and the fluctuation correlation state is an irrelevant state.

[0085] In other embodiments, the step of determining the fluctuation correlation state according to the fluctuation number of times, the opening and closing number of times, and the pre-acquired correlation relationship further includes:

[0086] The fluctuation termination time when the exhaust temperature of the compressor completes one fluctuation is recorded, and the opening and closing termination time when the liquid injection valve completes one opening and closing is recorded.

[0087] When the fluctuation number of times is equal to the opening and closing number of times, and the fluctuation termination time and the opening and closing termination time appear alternately, the fluctuation correlation state is a correlation state.

[0088] When the fluctuation number of times is not equal to the opening and closing number of times, or the fluctuation termination time and the opening and closing termination time do not appear alternately, the fluctuation correlation state is an irrelevant state.

[0089] It can be understood that, if it is determined that there is an over-temperature time and a low-temperature time between the adjacent two recorded times, the latter of the adjacent two recorded times is taken as the fluctuation termination time. The opening and closing of the liquid injection valve is controlled by the controller, and one opening and closing can be determined according to the adjacent two control signals including one low level and one high level. The time of each opening and closing is recorded, and the latter of the adjacent two recorded opening and closing times is taken as the opening and closing termination time.

[0090] After the opening or closing of the injection valve, the refrigerant temperature directly changes, but reaching the maximum or minimum point has a certain hysteresis. If the temperature fluctuation is caused by the opening and closing of the injection valve, the fluctuation termination time and the opening and closing termination time will appear alternately. If the above conditions are not met, it is indicated that the fluctuation correlation state is an unrelated state.

[0091] Referring to Figure 2 The control method of the multi-split air conditioning system provided by the embodiment of the present application comprises the following processes:

[0092] S200, obtaining the operation mode of the multi-split air conditioning system, obtaining the fluctuation frequency of the discharge temperature of the compressor within a first preset time length, obtaining the current frequency of the compressor and the opening and closing frequency of the injection valve within the first preset time length, recording the fluctuation termination time when the discharge temperature of the compressor completes one fluctuation, and recording the opening and closing termination time when the injection valve completes one opening and closing.

[0093] S210, judging whether the operation mode is the refrigeration mode and the fluctuation frequency is greater than or equal to a preset frequency.

[0094] If not, step S220 is executed; if yes, step S231 is executed.

[0095] S220, issuing a signal for controlling the operation frequency of the compressor to be the current frequency.

[0096] S231, judging whether the following condition is met: the fluctuation frequency is equal to the opening and closing frequency and the fluctuation termination time and the opening and closing termination time appear alternately.

[0097] If not, step S232 is executed; if yes, step S233 is executed.

[0098] S232, issuing a signal for controlling the operation frequency of the compressor to be the current frequency.

[0099] S233, determining that the fluctuation correlation state is the related state.

[0100] S240, judging whether the fluctuation correlation state is the related state.

[0101] If not, step S250 is executed; if yes, step S260 is executed.

[0102] S250, issuing a signal for controlling the operation frequency of the compressor to be the current frequency.

[0103] S260, issuing a signal for controlling the operation frequency of the compressor to be the target frequency.

[0104] It should be noted that the above process is only one embodiment of the control method of the multi-split air conditioning system. Other similar processes can be executed in step S260 when the operation mode is the cooling mode, the fluctuation frequency is greater than or equal to the preset frequency, and the fluctuation correlation state is the correlation state.

[0105] In some embodiments, the step of issuing a signal to control the operating frequency of the compressor to the target frequency further includes:

[0106] After the second preset time period, the number of fluctuations of the discharge temperature of the compressor within a third preset time period is obtained.

[0107] When the number of fluctuations is greater than zero, the opening degrees of the multiple indoor unit valves are obtained, and a signal is issued to adjust the minimum opening degree among the multiple opening degrees to a first target opening degree; wherein at the first target opening degree, the superheat degree of the evaporator of the corresponding indoor unit is reduced by a preset temperature.

[0108] It can be understood that after the operating frequency of the compressor is reduced to the target frequency, the suction temperature and the discharge temperature of the compressor will be reduced, and the opening and closing action of the liquid injection valve will be limited. However, there are many interference factors when the multi-split air conditioning system is running, and the control effect still needs to be detected and corrected.

[0109] After running for a second preset time period, for example, after running for 30 minutes, it can be detected again whether the discharge temperature of the compressor will still fluctuate within the next third preset time period. When the number of fluctuations is greater than zero, that is, the outlet air temperature fluctuation has not been completely solved, the opening degree of the indoor unit valve can be adjusted to adjust the suction temperature of the compressor.

[0110] The multi-split air conditioning system has multiple indoor units and multiple indoor unit valves, and there is a minimum opening degree among the multiple opening degrees. Increasing the minimum opening degree to a first target opening degree, for example, opening degree +1, at this time, the refrigerant flow in the evaporator of the corresponding indoor unit increases, and when the heat exchange efficiency does not change, the refrigerant temperature at the outlet of the evaporator decreases, the suction temperature of the compressor decreases, and the discharge temperature can be further reduced.

[0111] In this way, the frequency of the compressor can be further reduced, the compressor can be operated efficiently to meet the cooling demand, and the indoor unit valve with the minimum opening degree is adjusted, which has little effect on the heat exchange efficiency of other indoor units and has little effect on the corresponding indoor unit of the adjusted indoor unit valve.

[0112] In some embodiments, the step of issuing a signal to adjust the minimum opening degree among the multiple opening degrees to the first target opening degree further includes:

[0113] After the fourth preset time period, the number of fluctuations of the discharge temperature of the compressor within the first preset time period is obtained.

[0114] When the fluctuation frequency is greater than zero, the compressor is controlled again according to the fluctuation correlation state in the first preset time period.

[0115] It can be understood that the above steps are further adjustment strategies for the adjusted indoor unit valve. In the first stage, the fluctuation of the outlet air temperature is avoided by reducing the frequency of the compressor; in the second stage, the opening of the indoor unit valve is adjusted in a way that has the least impact; and in the third stage, the fluctuation of the outlet air temperature of the indoor unit is controlled again by adjusting the operating frequency of the compressor. In this way, the exhaust temperature of the compressor gradually tends to be within the first preset temperature and the second preset temperature, the outlet air temperature of the indoor unit fluctuates less, and the system is relatively stable and reliable.

[0116] In some embodiments, after the step of obtaining the fluctuation frequency of the exhaust temperature of the compressor in the third preset time period, the method further includes:

[0117] When the fluctuation frequency is zero, the current outdoor environment temperature is obtained, and a temperature difference between the current outdoor temperature and the initial outdoor environment temperature obtained at the start is calculated.

[0118] When the temperature difference is less than or equal to a preset temperature threshold, a signal is sent to control the operating frequency of the compressor to return to a preset frequency; wherein the preset frequency is determined according to the pre-stored compressor operating logic.

[0119] It can be understood that as the operating frequency of the compressor is reduced to the target frequency, the fluctuation frequency is reduced to zero, indicating that the above control strategy is effective. When the multi-split air conditioning system continues to operate, the outdoor environment temperature changes, for example, the outdoor environment temperature is higher at noon, steps S100 to S160 can be executed; when the outdoor environment temperature decreases in the afternoon, the exhaust temperature of the compressor rarely exceeds the temperature, at this time, the operating frequency of the compressor can be controlled to return to the preset frequency; wherein the preset frequency is determined according to the pre-stored compressor operating logic and is related to the outdoor environment temperature.

[0120] In some embodiments, when the fluctuation frequency is greater than zero, the control method of the multi-split air conditioning system further includes:

[0121] The current wind speed of the indoor fan is obtained, and the current wind speed of the indoor fan is adjusted to a target wind speed; wherein the wind speed difference between the current wind speed and the target wind speed is positively correlated with the preset temperature.

[0122] It can be understood that reducing the suction temperature of the compressor can effectively control the opening and closing actions of the liquid injection valve and the fluctuation of the outlet air temperature of the indoor unit. After the operating frequency of the compressor is reduced, if there is still temperature fluctuation, in order to maintain the high-efficiency operation of the compressor, the operating frequency of the compressor can not be continuously reduced, but the air speed of the indoor fan can be reduced to reduce the heat exchange efficiency between indoor air and refrigerant in the evaporator. At this time, the refrigerant temperature at the outlet of the evaporator is reduced, and the suction temperature of the compressor is also reduced, which can also achieve similar effects. Among them, the greater the air speed difference between the current air speed and the target air speed, the more the evaporator heat exchange efficiency is reduced, and the greater the preset temperature. The air speed difference and the preset temperature are positively correlated.

[0123] According to the control device of the multi-split air conditioning system provided in the second aspect of the present application, referring to Figure 3 , comprising:

[0124] The acquisition module 301 is configured to acquire the operating mode of the multi-split air conditioning system, the fluctuation frequency of the discharge temperature of the compressor within a first preset time length, the current frequency of the compressor, and the opening and closing frequency of the liquid injection valve within the first preset time length, and determine the fluctuation correlation state according to the fluctuation frequency, the opening and closing frequency, and the pre-acquired correlation relationship. The fluctuation correlation state includes an unrelated state and a related state.

[0125] The signal sending module 401 is configured to send a signal for controlling the operating frequency of the compressor to be a target frequency when the operating mode is the cooling mode, the fluctuation frequency is greater than or equal to a preset frequency, and the fluctuation correlation state is the related state. The target frequency is lower than the current frequency, and the frequency difference is a preset frequency difference.

[0126] It should be noted that the above steps S100 to S160 and other steps are only for convenience of description, and do not constitute a time sequence limitation of each step in the control method of the multi-split air conditioning system. Moreover, some contents are described in detail in the control method of the multi-split air conditioning system provided in the first aspect of the present application, and all the contents in the control method of the multi-split air conditioning system can also be applicable to the control device of the multi-split air conditioning system provided in the second aspect of the present application, and further to avoid repetition, the control device of the multi-split air conditioning system provided in the third aspect of the present application is not described in detail. Similarly, the contents in the above two aspects of the present application can be used to explain the contents of all the following aspects of the present application, so the repeated contents in the following aspects of the present application are not described in detail. The technical effects of the control device of the multi-split air conditioning system provided in the embodiments of the present application correspond to the technical effects of the control method of the multi-split air conditioning system, which will not be described here.

[0127] According to the third aspect of the present application, the multi-connected air conditioning system comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor executes the program to implement the steps of the control method of the multi-connected air conditioning system according to the first aspect of the present application.

[0128] Figure 4 An example of a schematic diagram of a physical structure of an electronic device is shown, which can include a processor 810, a communications interface 820, a memory 830, and a communications bus 840, wherein the processor 810, the communications interface 820, and the memory 830 communicate with each other through the communications bus 840. The processor 810 can invoke the logical instructions in the memory 830 to execute the control method of the multi-connected air conditioning system, which comprises: obtaining the operation mode of the multi-connected air conditioning system, the fluctuation frequency of the discharge temperature of the compressor within a first preset time length, the current frequency of the compressor, and the opening and closing frequency of the liquid injection valve within the first preset time length, and determining the fluctuation correlation state according to the fluctuation frequency, the opening and closing frequency, and the pre-acquired correlation relationship; wherein the fluctuation correlation state comprises an irrelevant state and a relevant state; when the operation mode is a cooling mode, the fluctuation frequency is greater than or equal to a preset frequency, and the fluctuation correlation state is the relevant state, a signal is sent to control the operation frequency of the compressor to be a target frequency; wherein the target frequency is lower than the current frequency, and the frequency difference is a preset frequency difference.

[0129] In addition, the logical instructions in the memory 830 described above can be implemented in the form of a software functional unit and sold or used as an independent product, which can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or part of the technical solutions can be embodied in the form of a software product, which is stored in a storage medium, includes several instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the method described in the embodiments of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0130] The device embodiments described above are merely illustrative, wherein the units described as separate components can or can not be physically separated, and the components displayed as units can or can not be physical units, i.e., can be located in one place, or can be distributed to multiple network units. Part or all of the modules can be selected to achieve the purposes of the embodiments according to actual needs. Those skilled in the art can understand and implement without creative labor.

[0131] Through the description of the above embodiments, those skilled in the art can clearly understand that the embodiments can be realized by means of software plus necessary general hardware platforms, and of course can also be realized by hardware. Based on such understanding, the above technical solutions, essentially or in other words, the part that contributes to the prior art, can be embodied in the form of a software product. The computer software product can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in the various embodiments or some parts of the embodiments.

[0132] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A control method of a multi VRF air conditioning system, characterized by, The refrigerant circulation loop of the multi-connected air conditioning system comprises a liquid injection valve, and the control method comprises the following steps: Obtaining the operation mode of the multi-connected air conditioning system, the fluctuation frequency of the discharge temperature of the compressor within a first preset time length, the current frequency of the compressor, and the opening and closing frequency of the liquid injection valve within the first preset time length, and determining the fluctuation correlation state according to the fluctuation frequency, the opening and closing frequency, and a previously obtained correlation relationship; wherein the fluctuation correlation state comprises an uncorrelated state and a correlated state; When the operation mode is a refrigeration mode, the fluctuation frequency is greater than or equal to a preset frequency, and the fluctuation correlation state is the correlated state, a signal for controlling the operation frequency of the compressor to be a target frequency is sent; wherein the target frequency is lower than the current frequency, and the frequency difference is a preset frequency difference.

2. The control method of a multi VRF air conditioning system according to claim 1, wherein, The fluctuation frequency of the discharge temperature of the compressor within a first preset time length is obtained by the following steps: Obtaining the discharge temperature of the compressor, and recording the over-temperature moment when the discharge temperature is greater than a first preset temperature obtained in advance and the low-temperature moment when the discharge temperature is less than a second preset temperature obtained in advance; When there is one over-temperature moment and one low-temperature moment between two adjacent recorded moments, it is determined that there is one fluctuation; According to all recorded moments within the first preset time length, the fluctuation frequency is determined.

3. The control method of a multi VRF air conditioning system according to claim 2, characterized in that, The step of determining the fluctuation correlation state according to the fluctuation frequency, the opening and closing frequency, and a previously obtained correlation relationship specifically comprises: When the fluctuation frequency is equal to the opening and closing frequency, the fluctuation correlation state is the correlated state; When the fluctuation frequency is not equal to the opening and closing frequency, the fluctuation correlation state is the uncorrelated state.

4. The control method of a multi VRF air conditioning system according to claim 2, wherein The step of determining the fluctuation correlation state according to the fluctuation frequency, the opening and closing frequency, and a previously obtained correlation relationship further comprises: Recording the fluctuation termination moment when the discharge temperature of the compressor completes one fluctuation, and recording the opening and closing termination moment when the liquid injection valve completes one opening and closing; When the fluctuation frequency is equal to the opening and closing frequency, and the fluctuation termination moment and the opening and closing termination moment appear alternately, the fluctuation correlation state is the correlated state; When the fluctuation frequency is not equal to the opening and closing frequency, or the fluctuation termination moment and the opening and closing termination moment do not appear alternately, the fluctuation correlation state is the uncorrelated state.

5. The control method of a multi VRF air conditioning system according to any one of claims 1 to 4, characterized in that, The multi-connected air conditioning system comprises a plurality of indoor units, and each evaporator inlet of the indoor units is provided with an indoor valve, and the step of sending a signal for controlling the operation frequency of the compressor to be a target frequency further comprises the following steps: After a second preset time length, the fluctuation frequency of the discharge temperature of the compressor within a third preset time length is obtained; When the fluctuation frequency is greater than zero, the opening degrees of the plurality of indoor valves are obtained, and a signal for adjusting the minimum opening degree among the plurality of opening degrees to a first target opening degree is sent; wherein at the first target opening degree, the superheat degree of the evaporator of the corresponding indoor unit is reduced by a preset temperature.

6. The control method of a multi VRF air conditioning system according to claim 5, wherein, The step of sending a signal for adjusting the minimum opening degree among the plurality of opening degrees to a first target opening degree further comprises the following steps: acquiring a fluctuation number of the discharge temperature of the compressor within a third preset time period; when the fluctuation number is greater than zero, re-controlling the compressor according to the fluctuation correlation state within the first preset time period.

7. The control method of a multi VRF air conditioning system according to claim 5, wherein The step of acquiring the fluctuation number of the discharge temperature of the compressor within the third preset time period further comprises: when the fluctuation number is zero, acquiring a current outdoor environment temperature and calculating a temperature difference between the current outdoor environment temperature and an initial outdoor environment temperature acquired at startup; when the temperature difference is less than or equal to a preset temperature threshold, sending a signal to control the operating frequency of the compressor to return to a preset frequency; wherein the preset frequency is determined according to a pre-stored compressor operating logic.

8. The control method of a multi VRF air conditioning system according to claim 5, wherein, when the fluctuation number is greater than zero, the control method further comprises: acquiring a current wind speed of an indoor fan and adjusting the current wind speed of the indoor fan to a target wind speed; wherein a wind speed difference between the current wind speed and the target wind speed is positively correlated with the preset temperature.

9. A control device of a multi VRF system, characterized by, comprises: an acquisition module for acquiring an operating mode of a multi-split air conditioning system, a fluctuation number of a discharge temperature of a compressor within a first preset time period, a current frequency of the compressor, and an opening and closing number of a liquid injection valve within the first preset time period, and determining a fluctuation correlation state according to the fluctuation number, the opening and closing number, and a pre-acquired correlation relationship; wherein the fluctuation correlation state comprises an irrelevant state and a relevant state; a signal sending module for sending a signal to control the operating frequency of the compressor to be a target frequency when the operating mode is a cooling mode, the fluctuation number is greater than or equal to a preset number, and the fluctuation correlation state is the relevant state; wherein the target frequency is lower than the current frequency, and a frequency difference is a preset frequency difference.

10. A multi-split air conditioning system comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the computer program comprises the following steps of: The processor implements the steps of the control method of the multi-split air conditioning system according to any one of claims 1 to 8 when executing the program.

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