Control method of multi-connected air conditioner and multi-connected air conditioner

Abstract

The present application relates to the technical field of air treatment equipment, and particularly relates to a control method of a multi-connected air conditioner and the multi-connected air conditioner. The control method of the multi-connected air conditioner comprises the following steps: obtaining the number of matched units and the opening degree of an expansion valve of a starting indoor unit before a load mutation; determining the load mutation of the multi-connected air conditioner; and controlling the opening degree of the expansion valve of each starting indoor unit after the load mutation according to at least the number of matched units and the opening degree of the expansion valve of the starting indoor unit before the load mutation. By using the control method, the total refrigerant circulation amount in the refrigeration system can be changed slowly, thereby avoiding the problems of compressor backflow, poor refrigeration effect and damage to the compressor, and shortening the time for the multi-connected air conditioner to reach a new balance, so that the energy-saving effect can be achieved.

Description

Technical Field

[0001] This invention relates to the field of air handling equipment technology, and in particular to a control method for a multi-split air conditioner and a multi-split air conditioner. Background Technology

[0002] Currently, in multi-split air conditioners, one outdoor unit is typically connected to multiple indoor units. Each indoor unit has an expansion valve, and the flow of refrigerant entering the indoor unit's heat exchanger is regulated by controlling the opening of the expansion valve, thereby achieving the exchange of heat and cold with the outside environment.

[0003] During the stable operation of a multi-split air conditioner, when a new indoor unit is detected to be turned on, the outdoor unit's operating frequency is increased to ensure the cooling effect of each indoor unit. However, when a new indoor unit is just turned on, the expansion valve opening is adjusted to a larger degree based on the superheat control of the indoor unit's inlet and outlet. This causes a sudden increase in the total refrigerant circulation in the refrigeration system, making the compressor prone to refrigerant backflow, resulting in poor cooling effect and even damage to the compressor. Consequently, the multi-split air conditioner cannot quickly and stably operate. Summary of the Invention

[0004] In view of the above problems, the present invention is proposed to provide a multi-split air conditioner control method and a multi-split air conditioner that overcomes or at least partially solves the above problems. The aim is to solve the problem of liquid return that easily occurs in existing multi-split air conditioners when the load changes suddenly, so as to shorten the time for the multi-split air conditioner to reach a new equilibrium.

[0005] On one hand, the present invention provides a control method for a multi-split air conditioner, comprising:

[0006] Obtain the horsepower of the indoor unit and the opening degree of the expansion valve before the load change;

[0007] Determine the sudden load change of the multi-split air conditioner;

[0008] Based at least on the horsepower of the indoor units that were started before the load change and the opening degree of the expansion valve, control the opening degree of the expansion valve of each indoor unit that was started after the load change.

[0009] Optionally, controlling the expansion valve opening of each indoor unit after the load change, based at least on the horsepower of the indoor unit before the load change and the expansion valve opening, includes:

[0010] Based on the horsepower of the indoor unit and the opening degree of the expansion valve before the load change, the total refrigerant opening degree required by the refrigeration system after the load change is obtained.

[0011] Based at least on the required total refrigerant opening and the horsepower and expansion valve opening of the indoor units before the load change, control the expansion valve opening of each indoor unit after the load change.

[0012] Optionally, determining the load fluctuation of the multi-split air conditioner includes:

[0013] If the number of indoor units of a multi-split air conditioner that are turned on increases during cooling operation, then a sudden change in the load of the multi-split air conditioner is determined.

[0014] Optionally, the control method is characterized by further comprising:

[0015] Obtain the compressor frequency before the load change;

[0016] After determining the sudden load change of the multi-split air conditioner, the method further includes:

[0017] Obtain the horsepower of the indoor unit after a sudden load change;

[0018] The compressor frequency change value is obtained based on the number of indoor units started before the load change, the compressor frequency, and the number of indoor units started after the load change.

[0019] Optionally, the frequency change value is the up-frequency value;

[0020] The formula for calculating the up-frequency value is:

[0021] Fnew=(Hsum+Hnew) / Hsum*α*F0;

[0022] Where Fnew is the up-frequency value;

[0023] Hsum is the total number of indoor units turned on before the load change;

[0024] Hnew is the horsepower of the newly turned-on indoor unit;

[0025] α is a correction factor, ranging from 0.5 to 2;

[0026] F0 is the compressor frequency before the load change.

[0027] Optionally, controlling the expansion valve opening of each indoor unit after the load change, based at least on the required total refrigerant opening and the horsepower and expansion valve opening of the indoor units before the load change, includes:

[0028] Based at least on the required total refrigerant opening and the horsepower and expansion valve opening of the indoor units before the load change, the expansion valve opening of each indoor unit after the load change is obtained and denoted as the third opening.

[0029] If the third opening degree is greater than the first opening degree, then the indoor unit is controlled to perform the first opening degree;

[0030] If the third opening degree is less than the second opening degree, then control the indoor unit to execute the second opening degree;

[0031] If the third opening degree is not greater than the first opening degree and not less than the second opening degree, then control the indoor unit to execute the third opening degree;

[0032] The first opening is greater than the second opening.

[0033] Optionally, the formula for calculating the required total refrigerant opening is:

[0034] Pneed=(ΣHi*Ai)*N1

[0035] Where Pneed is the total required refrigerant opening;

[0036] Hi is the horsepower of indoor unit i before the load change;

[0037] Ai is the opening degree of the expansion valve of indoor unit i before the load change;

[0038] N1 is a preset scaling factor, ranging from 0.5 to 2.

[0039] Optionally, based at least on the required total refrigerant opening and the horsepower and expansion valve opening of the indoor units before the load change, the opening of the expansion valve of each indoor unit after the load change is controlled, including:

[0040] The opening degree of the expansion valve of the newly started indoor unit can be obtained by using the formula Pnew=Pneed*Hnew / (Hsum+Hnew);

[0041] The opening degree of the expansion valve of the original indoor unit i can be obtained by using the formula Pi=Ai-Pnew / Hnew*Hi;

[0042] Where Pnew is the opening degree of the expansion valve of the newly opened indoor unit;

[0043] Pneed is the required total refrigerant opening;

[0044] Hsum is the total horsepower of the indoor units that were turned on before the load change;

[0045] Hnew is the horsepower of the newly turned-on indoor unit;

[0046] Pnew is the opening degree of the expansion valve of the newly started indoor unit;

[0047] Pi is the opening degree of the expansion valve of the original indoor unit i after the load change;

[0048] Ai is the opening degree of the expansion valve of indoor unit i before the load change;

[0049] Hi is the horsepower of the indoor unit i before the load change.

[0050] Optionally, the method of controlling the expansion valve opening of each indoor unit after the load change, based at least on the horsepower of the indoor unit before the load change and the expansion valve opening, further includes:

[0051] After a preset time, the opening of the expansion valve of the indoor unit is controlled according to the superheat of the indoor unit's inlet and outlet.

[0052] The present invention also provides a multi-split air conditioner, which includes a controller. The controller includes a memory and a processor. The memory stores a control program. When the control program is executed by the processor, it is used to implement the control method of the multi-split air conditioner as described in any of the above.

[0053] In the control method of the present invention, if the load of the multi-split air conditioner changes suddenly during stable operation, the opening of the expansion valve of each indoor unit after the load change is forcibly controlled at least according to the horsepower of the indoor unit before the load change and the opening of the expansion valve, so as to make the total amount of refrigerant circulating in the refrigeration system of the multi-split air conditioner change slowly.

[0054] Furthermore, by employing the control method of the present invention, the problem of a sudden increase in the total refrigerant circulation volume in the refrigeration system caused by excessive opening of the expansion valve when the load changes abruptly can be avoided in the prior art, thereby preventing the compressor from returning liquid, resulting in poor refrigeration effect and damage to the compressor.

[0055] Furthermore, by employing the control method of this invention, the time required for a multi-split air conditioner to reach a new equilibrium can be shortened, thereby achieving energy savings.

[0056] Furthermore, the control method of the present invention has the advantages of simple control procedures and easy execution.

[0057] Therefore, those skilled in the art will more readily understand the above and other objects, advantages and features of the present invention from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0058] The following sections will describe some specific embodiments of the invention in a detailed manner by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0059] Figure 1 This is a schematic flowchart of a control method for a multi-split air conditioner according to an embodiment of the present invention;

[0060] Figure 2 This is a schematic flowchart of a control method for a multi-split air conditioner according to an embodiment of the present invention;

[0061] Figure 3 This is a schematic flowchart of a control method for a multi-split air conditioner according to an embodiment of the present invention;

[0062] Figure 4 This is a schematic flowchart of a control method for a multi-split air conditioner according to an embodiment of the present invention;

[0063] Figure 5 This is a schematic flowchart of a control method for a multi-split air conditioner according to an embodiment of the present invention;

[0064] Figure 6 This is a schematic flowchart of a control method for a multi-split air conditioner according to an embodiment of the present invention;

[0065] Figure 7 This is a schematic flowchart of a control method for a multi-split air conditioner according to an embodiment of the present invention;

[0066] Figure 8 This is a schematic flowchart of a control method for a multi-split air conditioner according to an embodiment of the present invention;

[0067] Figure 9 This is a schematic structural diagram of the controller in a multi-split air conditioner according to an embodiment of the present invention. Detailed Implementation

[0068] The following reference Figures 1 to 9 This invention describes a multi-split air conditioner control method and a multi-split air conditioner according to embodiments of the present invention. The terms "front," "rear," "upper," "lower," "top," "bottom," "inner," "outer," and "lateral," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0069] The terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first," "second," etc., may explicitly or implicitly include at least one of that feature, that is, include one or more of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. When a feature "includes or contains" one or more of the features it encompasses, unless otherwise specifically stated, this indicates that other features are not excluded and may be further included.

[0070] Unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," and "coupling," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art should be able to understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0071] In existing technologies, after a low-load indoor unit has been running for a period of time, a significant refrigerant return occurs when a new high-load indoor unit is started, which can easily damage the compressor. Therefore, when the load of a multi-split air conditioner increases, this invention forcibly controls the valve opening of multiple indoor units to balance the increase in refrigerant caused by the newly started indoor unit, ensuring cooling performance, preventing compressor refrigerant return, and shortening the time it takes for the system to reach a new equilibrium.

[0072] Figure 1 This is a schematic flowchart of a control method for a multi-split air conditioner according to an embodiment of the present invention, and in conjunction with... Figure 2-9 This invention provides a control method for multi-split air conditioners.

[0073] like Figure 1 As shown, the control method for a multi-split air conditioner includes the following steps:

[0074] Step S11: Obtain the horsepower of the indoor unit before the load change and the opening degree of the expansion valve.

[0075] Step S12: Determine the load change of the multi-split air conditioner.

[0076] Step S13: Based at least on the horsepower of the indoor units that were turned on before the load change and the opening degree of the expansion valve, control the opening degree of the expansion valve of each indoor unit that was turned on after the load change.

[0077] Multi-split air conditioners, also known as one-to-many air conditioners, consist of one indoor unit and multiple outdoor units. Each indoor unit is equipped with an expansion valve on the connecting pipes between it and the outdoor unit. Multiple indoor units are connected in parallel with the outdoor unit to form a refrigeration system. When the air conditioner is cooling or heating, the outdoor unit starts operating, and all or some of the indoor units start operating. The operating indoor units use indoor heat exchangers to regulate the indoor air temperature, providing a comfortable environment for people indoors.

[0078] In this embodiment, if the load of the multi-split air conditioner changes suddenly during stable operation, the opening of the expansion valve of each indoor unit after the load change is forcibly controlled based at least on the horsepower of the indoor unit before the load change and the opening of the expansion valve, so as to make the total refrigerant circulation in the refrigeration system of the multi-split air conditioner change slowly.

[0079] Furthermore, by adopting the control method of this embodiment, the problem of a sudden increase in the total refrigerant circulation volume in the refrigeration system caused by excessive expansion valve opening when the load changes abruptly, as in the prior art, can be avoided, thereby preventing compressor liquid return, deterioration of refrigeration effect and damage to the compressor.

[0080] Furthermore, by adopting the control method of this embodiment, the time for multi-split air conditioners to reach a new equilibrium can be shortened, thereby achieving energy saving.

[0081] Furthermore, the control method of the present invention has the advantages of simple control procedures and easy execution.

[0082] In some embodiments of the present invention, determining a load change in a multi-split air conditioner includes: if the number of indoor units of the multi-split air conditioner increases during cooling operation, then a load change in the multi-split air conditioner is determined.

[0083] Specifically, when a multi-split air conditioner is operating in cooling mode and running stably, if the number of indoor units turned on increases, it indicates a sudden change in the load of the multi-split air conditioner. In particular, if a new high-load indoor unit is turned on after a low-load indoor unit has been running for a period of time, it indicates a sudden change in the load of the multi-split air conditioner.

[0084] like Figure 2 As shown, in some embodiments of the present invention, step S13, controlling the expansion valve opening of each indoor unit after the load change based at least on the horsepower of the indoor unit before the load change and the expansion valve opening, includes the following steps:

[0085] Step S131: Based on the horsepower of the indoor unit before the load change and the opening degree of the expansion valve, obtain the total refrigerant opening degree required by the refrigeration system after the load change.

[0086] Step S132: Based at least on the required total refrigerant opening and the horsepower and expansion valve opening of the indoor units before the load change, control the expansion valve opening of each indoor unit after the load change.

[0087] Specifically, firstly, the total refrigerant opening degree required by the refrigeration system after the load change is obtained, and then the opening degree of the expansion valve of each indoor unit after the load change is obtained, and the expansion valve of each indoor unit is controlled to perform the above opening degree.

[0088] In step S131, the required total refrigerant opening of the refrigeration system after the load change is obtained by using the "horsepower of the indoor unit before the load change and the opening degree of the expansion valve" as parameters. Therefore, the required total refrigerant opening of the refrigeration system after the load change will not change significantly compared to the total refrigerant opening of the refrigeration system before the load change, thus effectively avoiding a sudden increase in the total refrigerant circulation volume in the refrigeration system. Therefore, step S131 has the advantages of scientific design and ease of operation.

[0089] In step S132, the expansion valve openings of both the existing and newly started indoor units are controlled based on the total refrigerant opening required by the refrigeration system after the load change, as well as the horsepower and expansion valve opening of the indoor units before the load change. This step S132 is scientifically and reasonably designed, which can avoid a sudden increase in the refrigerant circulation volume of the refrigeration system caused by the load change, thereby allowing the refrigerant circulation volume of the refrigeration system to increase slowly and effectively preventing liquid return.

[0090] Therefore, by using the control method of this embodiment, the service life of the compressor can be extended, the cooling effect can be guaranteed, and the time for the multi-split air conditioner to reach a new equilibrium can be shortened, thereby achieving energy saving.

[0091] In some embodiments of the present invention, the control method of a multi-split air conditioner further includes the following step: step S14, obtaining the compressor frequency before the load change.

[0092] Step S12 involves determining the load change of the multi-split air conditioner, followed by the following steps:

[0093] Step S15: Obtain the horsepower of the indoor unit after the load change.

[0094] Step S16: Based on the number of indoor units started before the load change, the compressor frequency, and the number of indoor units started after the load change, obtain the compressor frequency change value.

[0095] Specifically, such as Figure 3 As shown, in this embodiment, the control method for a multi-split air conditioner includes the following steps:

[0096] Step S11: Obtain the horsepower of the indoor unit before the load change and the opening degree of the expansion valve.

[0097] Step S14: Obtain the compressor frequency before the load change.

[0098] Step S12: Determine the load change of the multi-split air conditioner.

[0099] Step S13: Based at least on the horsepower of the indoor units that were turned on before the load change and the opening degree of the expansion valve, control the opening degree of the expansion valve of each indoor unit that was turned on after the load change.

[0100] Step S15: Obtain the horsepower of the indoor unit after the load change.

[0101] Step S16: Based on the number of indoor units started before the load change, the compressor frequency, and the number of indoor units started after the load change, obtain the compressor frequency change value.

[0102] When a multi-split air conditioner is operating in cooling mode and running stably, if a sudden change in the load of the multi-split air conditioner is determined, not only step S13 but also step S16 will be executed. Steps S13 and S16 can be executed simultaneously, and there is no order between them.

[0103] In other words, when a multi-split air conditioner is operating in cooling mode and running stably, if the number of indoor units in the multi-split air conditioner increases, it will not only forcibly control the opening of the expansion valve of each indoor unit, but also control the compressor frequency according to the number of indoor units in operation before the load change, the compressor frequency, and the number of indoor units in operation after the load change, in order to avoid excessive changes in the compressor frequency.

[0104] Since the opening degree of the expansion valve of each indoor unit and the compressor frequency are both important factors affecting the refrigerant circulation volume of the refrigeration system, the compressor is the core component of the refrigeration system, and its operating frequency directly affects the cooling effect. A higher compressor operating frequency results in a larger cooling capacity and faster cooling speed, but also increases operating noise. Conversely, a lower compressor operating frequency results in a gradual decrease in cooling capacity and reduced noise. Therefore, in this embodiment, by controlling the opening degree of the expansion valve of each indoor unit and the operating frequency of the compressor, the total refrigerant circulation volume in the multi-split air conditioning system is controlled. This further avoids sudden increases in refrigerant circulation volume caused by load changes, allowing the refrigerant circulation volume to increase slowly, thus more effectively preventing liquid return and accelerating the multi-split air conditioning system to reach a new equilibrium.

[0105] Furthermore, in some embodiments of the present invention, the frequency change value is the up-frequency value.

[0106] The formula for calculating the up-frequency value is:

[0107] Fnew=(Hsum+Hnew) / Hsum*α*F0

[0108] Where Fnew is the frequency increase value; Hsum is the total horsepower of the indoor units that were started before the load change; Hnew is the horsepower of the newly started indoor units; α is the correction factor, which is 0.5 to 2; and F0 is the compressor frequency before the load change.

[0109] Specifically, "Hsum+Hnew" refers to the total horsepower of the indoor units after a sudden load change in the multi-split air conditioner. In step S16, the compressor frequency change value is calculated using the above formula and based on the total horsepower of the indoor units before the load change, the compressor frequency, and the total horsepower of the indoor units after the load change.

[0110] The correction factor α can be 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2. The correction factor α can be set according to actual needs.

[0111] In this embodiment, the above formula is scientifically and rationally designed. This formula allows for the rapid and accurate calculation of the compressor's frequency increase, enabling quick and reasonable control of the compressor's operating frequency. This, in turn, helps control the refrigerant circulation in the refrigeration system to increase slowly, thus more effectively preventing liquid return and further accelerating the multi-split air conditioner's journey to a new equilibrium.

[0112] Preferably, in some embodiments of the present invention, the correction coefficient α is 1.1.

[0113] like Figure 4 As shown, in some optional embodiments of the present invention, step S13, controlling the expansion valve opening of each indoor unit after the load change based at least on the required total refrigerant opening and the horsepower and expansion valve opening of the indoor unit before the load change, includes the following steps:

[0114] Step S133: Based at least the required total refrigerant opening degree and the horsepower and expansion valve opening degree of the indoor units before the load change, obtain the expansion valve opening degree of each indoor unit after the load change, and record it as the third opening degree.

[0115] Step S134: If the third opening degree is greater than the first opening degree, then control the indoor unit to execute the first opening degree.

[0116] Step S135: If the third opening degree is less than the second opening degree, then control the indoor unit to execute the second opening degree.

[0117] Step S136: If the third opening degree is not greater than the first opening degree and not less than the second opening degree, then control the indoor unit to execute the third opening degree.

[0118] The first opening is greater than the second opening.

[0119] There is no specific order between steps S134, S135, and S136.

[0120] Specifically, after step S133, the relationship between the third opening degree obtained in step S133 and the first and second opening degrees is determined. If the third opening degree obtained in step S133 is greater than the first opening degree, the expansion valve of the indoor unit is controlled to execute the first opening degree. If the third opening degree obtained in step S133 is less than the second opening degree, the expansion valve of the indoor unit is controlled to execute the second opening degree. If the third opening degree obtained in step S133 is within the range of [first opening degree, second opening degree], the expansion valve of the indoor unit is controlled to execute the third opening degree.

[0121] Furthermore, in some embodiments of the present invention, the first opening degree is the upper limit of the expansion valve opening degree, and the second opening degree is the lower limit of the expansion valve opening degree.

[0122] For example, the upper limit of the expansion valve opening is 470 steps, and the lower limit of the expansion valve opening is 52 steps.

[0123] The specific values ​​of the upper and lower limits of the expansion valve opening can be determined based on the actual expansion valve range.

[0124] In other embodiments of the invention, the first opening degree is less than the upper limit of the expansion valve opening degree.

[0125] In other embodiments of the invention, the second opening degree is greater than the lower limit of the expansion valve opening degree.

[0126] In some embodiments of the present invention, the formula for calculating the required total refrigerant opening is as follows:

[0127] Pneed=(ΣHi*Ai)*N1

[0128] Here, Pneed is the total required refrigerant opening.

[0129] Hi is the horsepower of the indoor unit i before the load change.

[0130] Ai is the opening degree of the expansion valve of indoor unit i before the load change.

[0131] N1 is the preset scaling factor.

[0132] Specifically, in step S131, the total refrigerant opening required by the refrigeration system after a sudden load change can be quickly and scientifically calculated according to the above formula.

[0133] N1 ranges from 0.5 to 2. For example, the preset scaling factor N1 can be any one of 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2. Specifically, the preset scaling factor N1 can be set according to actual needs.

[0134] In some preferred embodiments of the present invention, the preset scaling factor N1 is 1.1.

[0135] like Figure 5 As shown, in some embodiments of the present invention, step S132, controlling the expansion valve opening of each indoor unit after a load change based at least on the required total refrigerant opening and the horsepower and expansion valve opening of the indoor unit before the load change, includes the following steps:

[0136] Step S1321: According to the formula Pnew=Pneed*Hnew / (Hsum+Hnew), the opening degree of the expansion valve of the newly started indoor unit is obtained.

[0137] Step S1322: According to the formula Pi=Ai-Pnew / Hnew*Hi, the opening degree of the expansion valve of the original indoor unit i is obtained.

[0138] Pnew is the opening degree of the expansion valve of the newly opened indoor unit.

[0139] Pneed is the required total refrigerant opening level.

[0140] Hsum is the total horsepower of the indoor units that were turned on before the load change.

[0141] Hnew is the horsepower of the newly turned-on indoor unit.

[0142] Pnew is the opening degree of the expansion valve of a newly started indoor unit.

[0143] Pi is the opening degree of the expansion valve of the original indoor unit i after a sudden load change.

[0144] Ai is the opening degree of the expansion valve of indoor unit i before the load change.

[0145] Hi is the horsepower of the indoor unit i before the load change.

[0146] There is no existing order between steps S1321 and S1322, and they can be performed simultaneously.

[0147] In this embodiment, a formula is provided for calculating the expansion valve opening of a newly started indoor unit, and another formula is provided for calculating the expansion valve opening of an existing indoor unit after a sudden load change. Based on these two formulas, the expansion valve opening of both the newly started and existing indoor units can be calculated quickly and reasonably. This improves the efficiency of adjusting the expansion valve opening, thus facilitating the rapid achievement of a new equilibrium for the multi-split air conditioner.

[0148] like Figure 6 As shown, in some embodiments of the present invention, after step S1321, the control method for a multi-split air conditioner further includes the following steps:

[0149] Step S1323: If Pnew is greater than the first opening degree, then control the expansion valve of the indoor unit to execute the first opening degree.

[0150] Step S1324: If Pnew is less than the second opening degree, then control the expansion valve of the indoor unit to execute the second opening degree.

[0151] Step S1325: If Pnew is not greater than the first opening degree and not less than the second opening degree, then control the expansion valve of the indoor unit to execute Pnew.

[0152] The first opening is greater than the second opening.

[0153] Specifically, there is no specific order among steps S1323, S1324, and S1325.

[0154] like Figure 7 As shown, in some embodiments of the present invention, after step S1322, the control method for a multi-split air conditioner further includes the following steps:

[0155] Step S1326: If Pi is greater than the first opening degree, then control the expansion valve of the indoor unit to perform the first opening degree.

[0156] Step S1327: If Pi is less than the second opening degree, control the expansion valve of the indoor unit to perform the second opening degree.

[0157] Step S1328: If Pi is not greater than the first opening degree and not less than the second opening degree, then control the expansion valve of the indoor unit to execute Pi.

[0158] Specifically, there is no specific order among steps S1326, S1327, and S1328.

[0159] In the two embodiments described above, the first opening degree is the upper limit of the expansion valve opening degree, and the second opening degree is the lower limit of the expansion valve opening degree. For example, the upper limit of the expansion valve opening degree is 470 steps, and the lower limit of the expansion valve opening degree is 52 steps. The specific values ​​of the upper and lower limits of the expansion valve opening degree can be determined according to the actual expansion valve range.

[0160] like Figure 8 As shown, in some embodiments of the present invention, step S13, which involves controlling the expansion valve opening of each indoor unit after the load change based at least on the horsepower of the indoor unit before the load change and the expansion valve opening, further includes the following steps:

[0161] Step S17: After a preset time, control the opening of the expansion valve of the indoor unit according to the superheat of the indoor unit's inlet and outlet.

[0162] Furthermore, the preset time is 0.5 to 3 minutes.

[0163] For example, the preset time can be 0.5 min, 0.8 min, 0.8 min, 1 min, 1.5 min, 2 min, 2.5 min, 2.8 min, or 3 min. The preset time can be set according to usage requirements.

[0164] Preferably, the preset time is 1 minute.

[0165] like Figure 9 As shown, the present invention also provides a multi-split air conditioner. The multi-split air conditioner includes a controller 500, which includes a memory 520 and a processor 510. The memory 520 stores a control program 521. When the control program 521 is executed by the processor 510, it is used to implement the control method of the multi-split air conditioner as described in any of the above embodiments.

[0166] During stable operation, if the load of a multi-split air conditioner changes suddenly, the total amount of refrigerant circulating in the refrigeration system can change slowly. This can prevent the compressor from returning liquid, resulting in poor cooling effect and damage to the compressor. In turn, it can shorten the time for the multi-split air conditioner to reach a new equilibrium, thus achieving energy saving.

[0167] While this invention provides several exemplary embodiments, many other variations or modifications consistent with the principles of this invention can be directly determined or derived from the disclosure of this invention without departing from its spirit and scope. Therefore, the scope of this invention should be understood and recognized as covering all such other variations or modifications.

Claims

1. A control method for a multi-split air conditioner, characterized in that, include: Obtain the horsepower of the indoor unit and the opening degree of the expansion valve before the load change; Determine the sudden load change of the multi-split air conditioner; Based at least on the horsepower of the indoor units that were started before the load change and the opening degree of the expansion valve, control the opening degree of the expansion valve of each indoor unit that was started after the load change. The aforementioned control of the expansion valve opening of each indoor unit after a load change, based at least on the horsepower of the indoor unit before the load change and the opening degree of the expansion valve, includes: Based on the horsepower of the indoor unit and the opening degree of the expansion valve before the load change, the total refrigerant opening degree required by the refrigeration system after the load change is obtained. Based at least on the required total refrigerant opening and the horsepower and expansion valve opening of the indoor units before the load change, control the expansion valve opening of each indoor unit after the load change. Based at least on the required total refrigerant opening and the horsepower and expansion valve opening of the indoor units before the load change, control the expansion valve opening of each indoor unit after the load change, including: The opening degree of the expansion valve of the newly started indoor unit can be obtained according to the formula Pnew = Pneed*Hnew / (Hsum + Hnew); The opening degree of the expansion valve of the original indoor unit i can be obtained by using the formula Pi=Ai-Pnew / Hnew*Hi; Where Pnew is the opening degree of the expansion valve of the newly opened indoor unit; Pneed is the required total refrigerant opening; Hsum is the total horsepower of the indoor units that were turned on before the load change; Hnew is the horsepower of the newly turned-on indoor unit; Pnew is the opening degree of the expansion valve of the newly started indoor unit; Pi is the opening degree of the expansion valve of the original indoor unit i after the load change; Ai is the opening degree of the expansion valve of indoor unit i before the load change; Hi is the horsepower of the indoor unit i before the load change.

2. The control method according to claim 1, characterized in that, The determination of the load change of the multi-split air conditioner includes: If the number of indoor units of a multi-split air conditioner that are turned on increases during cooling operation, then a sudden change in the load of the multi-split air conditioner is determined.

3. The control method according to claim 1, characterized in that, Also includes: Obtain the compressor frequency before the load change; After determining the sudden load change of the multi-split air conditioner, the method further includes: Obtain the horsepower of the indoor unit after a sudden load change; The compressor frequency change value is obtained based on the number of indoor units started before the load change, the compressor frequency, and the number of indoor units started after the load change.

4. The control method according to claim 3, characterized in that, The frequency change value is the up-frequency value; The formula for calculating the up-frequency value is: Fnew= (Hsum+Hnew) / Hsum*α* F0; Where Fnew is the up-frequency value; Hsum is the total number of indoor units turned on before the load change; Hnew is the horsepower of the newly turned-on indoor unit; α is a correction factor, ranging from 0.5 to 2; F0 is the compressor frequency before the load change.

5. The control method according to claim 1, characterized in that, The aforementioned control of the expansion valve opening of each indoor unit after a load change, based at least on the required total refrigerant opening and the horsepower and expansion valve opening of the indoor units before the load change, includes: Based at least on the required total refrigerant opening and the horsepower and expansion valve opening of the indoor units before the load change, the expansion valve opening of each indoor unit after the load change is obtained and denoted as the third opening. If the third opening degree is greater than the first opening degree, then control the indoor unit to perform the first opening degree; If the third opening degree is less than the second opening degree, then control the indoor unit to perform the second opening degree; If the third opening degree is not greater than the first opening degree and not less than the second opening degree, then control the indoor unit to perform the third opening degree. The first opening is greater than the second opening.

6. The control method according to claim 1, characterized in that, The formula for calculating the required total refrigerant opening is as follows: Pneed = (ΣHi * Ai) * N1 Where Pneed is the total required refrigerant opening; Hi is the horsepower of indoor unit i before the load change; Ai is the opening degree of the expansion valve of indoor unit i before the load change; N1 is a preset scaling factor, ranging from 0.5 to 2.

7. The control method according to claim 1, characterized in that, The method of controlling the expansion valve opening of each indoor unit after a load change, based at least on the horsepower of the indoor unit before the load change and the opening degree of the expansion valve, further includes: After a preset time, the opening of the expansion valve of the indoor unit is controlled according to the superheat of the indoor unit's inlet and outlet.

8. A multi-split air conditioner, characterized in that, The system includes a controller, which comprises a memory and a processor. The memory stores a control program, which, when executed by the processor, is used to implement the control method for a multi-split air conditioner as described in any one of claims 1 to 7.

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