An air conditioning system and its control method

Abstract

This application provides an air conditioning system and its control method, relating to the field of air conditioning technology, for simultaneously controlling multiple indoor units from one outdoor unit when multiple indoor units are connected to an outdoor unit. The air conditioning system includes: an outdoor fan; multiple indoor units; a compressor; a pressure sensor for detecting the compressor's discharge pressure value; and a controller configured to: acquire a first discharge pressure value of the compressor at a first moment via the pressure sensor; determine a maximum target pressure value from a first target pressure value and a second target pressure value, wherein the first target pressure value is the target discharge pressure value of the compressor when the first indoor unit operates in a first mode, and the second target pressure value is the target discharge pressure value of the compressor when the second indoor unit operates in a second mode; and adjust the speed of the outdoor fan based on the difference between the maximum target pressure value and the first discharge pressure value, so that the compressor's discharge pressure value reaches the maximum target pressure value.

Description

Technical Field

[0001] This application relates to the field of air conditioning technology, and in particular to an air conditioning system and its control method. Background Technology

[0002] With economic and social development, air conditioners are increasingly used in various places such as entertainment, home, and work, and people have higher requirements for their functionality. Especially during the plum rain season and the return of warm, humid weather, indoor air temperature may be low but humidity may be too high, which can lead to a decrease in user comfort.

[0003] Current air conditioners on the market cannot achieve dual control of indoor temperature and humidity. Furthermore, if there are more than two indoor units, it is impossible for one outdoor unit to control multiple indoor units operating in different modes. How to achieve a suitable indoor temperature and humidity level—that is, reducing humidity while maintaining a comfortable temperature—and how to enable one outdoor unit to control multiple indoor units operating in different modes, have become pressing problems that need to be solved. Summary of the Invention

[0004] This application provides an air conditioning system and its control method, which enables one outdoor unit to simultaneously control multiple indoor units under different operating modes when the outdoor unit is connected to two or more indoor units.

[0005] To achieve the above objectives, this application adopts the following technical solution.

[0006] In a first aspect, embodiments of this application provide an air conditioning system, which includes: an outdoor fan; multiple indoor units; a compressor; a pressure sensor for detecting the discharge pressure value of the compressor; and a controller configured to: acquire a first discharge pressure value of the compressor at a first moment through the pressure sensor; determine a maximum target pressure value from a first target pressure value and a second target pressure value, wherein the first target pressure value is the target discharge pressure value of the compressor when the first indoor unit among the multiple indoor units is operating in a first mode, and the second target pressure value is the target discharge pressure value of the compressor when the second indoor unit among the multiple indoor units is operating in a second mode; and adjust the speed of the outdoor fan based on the difference between the maximum target pressure value and the first discharge pressure value so that the discharge pressure value of the compressor reaches the maximum target pressure value.

[0007] The technical solution provided in this application provides at least the following beneficial effects: The controller of the air conditioning system controls the outdoor fan to operate at the initial fan speed based on the compressor's discharge pressure value. When one indoor unit of the air conditioning system operates in a first mode and another indoor unit operates in a second mode, the controller can obtain the first discharge pressure value of the compressor at a first moment through a pressure sensor. Based on the first discharge pressure value, the target pressure value corresponding to the first mode, and the target pressure value corresponding to the second mode, the controller adjusts the speed of the outdoor fan so that the compressor's discharge pressure reaches the maximum target pressure value. This allows the first indoor unit to operate in the first mode, while the second indoor unit can operate in the second mode. In other words, even when the first and second modes are different, multiple indoor units operating in different modes can be controlled by adjusting the speed of the outdoor fan in one outdoor unit.

[0008] In some embodiments, the first mode is a temperature-controlled dehumidification mode and the second mode is a cooling mode; or, both the first mode and the second mode are temperature-controlled dehumidification modes.

[0009] In some embodiments, the controller is further configured such that, in the case of a first mode being a temperature-controlled dehumidification mode and a second mode being a cooling mode, the first indoor heat exchanger of the first indoor unit operates as a condenser, the second indoor heat exchanger of the first indoor unit operates as an evaporator, and the third and fourth indoor heat exchangers controlling the second indoor unit both operate as evaporators.

[0010] In some embodiments, the air conditioning system further includes: a first temperature sensor for detecting the return air temperature of the first indoor heat exchanger; and a controller further configured to: acquire a first return air temperature at a first moment and a second return air temperature at a second moment via the first temperature sensor; and adjust a first target pressure value based on a second temperature difference between the second return air temperature and a preset temperature of the first indoor unit and the temperature difference change rate of the first indoor unit at the second moment, wherein the temperature difference change value is the change between the second temperature difference and the first temperature difference, and the first temperature difference is the temperature difference between the first return air temperature and the preset temperature of the first indoor unit.

[0011] It is understandable that the target exhaust pressure value set for the first indoor unit operating in temperature-controlled dehumidification mode can vary. The controller can adjust the target pressure value based on the environmental conditions of the first indoor unit, such as the temperature difference between the return air temperature and the set temperature, and the rate of change of the temperature difference, so that the redefined target pressure value is more in line with the current environmental conditions of the first indoor unit. Furthermore, compared to the commonly used cooling and dehumidification mode of air conditioners, the temperature-controlled dehumidification mode provided in this application can achieve dual control of room temperature and humidity. It can control the required indoor ambient temperature to prevent the ambient temperature from becoming too low, while also reducing indoor humidity to meet the user's comfort needs.

[0012] In some embodiments, the air conditioning system further includes: a first temperature sensor for detecting the return air temperature of the first indoor unit; a second temperature sensor for detecting the return air temperature of the second indoor unit; a first expansion valve for regulating the refrigerant flow rate in the pipeline between the first indoor unit and the outdoor unit; a second expansion valve for regulating the refrigerant flow rate in the pipeline between the second indoor unit and the outdoor unit; and a controller further configured to: when both the first mode and the second mode are temperature control and dehumidification modes, obtain the second discharge pressure value of the compressor at a second moment through a pressure sensor, and obtain the first return air temperature through the first temperature sensor, and obtain the second return air temperature through the second temperature sensor. Air temperature; the second moment is the moment after the first moment; when the second exhaust pressure value reaches the maximum target pressure value, if the first target pressure value is greater than or equal to the second target pressure value, the opening of the second expansion valve is adjusted according to the second target pressure value and the saturation pressure value under the second return air temperature, so that the saturation pressure value under the return air temperature of the second indoor unit reaches the exhaust pressure value of the compressor; or, if the first target pressure value is less than the second target pressure value, the opening of the first expansion valve is adjusted according to the first target pressure value and the saturation pressure value under the first return air temperature, so that the saturation pressure value under the return air temperature of the first indoor unit reaches the exhaust pressure value of the compressor.

[0013] It should be noted that when both indoor units are running in temperature-controlled dehumidification mode, the corresponding indoor ambient temperature (the aforementioned return air temperature) can be obtained from the intake air temperature sensor. If the ambient temperatures of the two indoor units are different, and the set temperatures of the two temperature-controlled dehumidification indoor units are also different, the change value of the target pressure is obtained based on the temperature difference and the rate of change of the temperature difference between the return air temperature and the set temperature. This is then used to determine the target value of the exhaust pressure for the next step, ultimately achieving consistency between the indoor unit ambient temperature and the set temperature. This improves the efficiency of setting the air conditioning system for users and optimizes the user experience.

[0014] Secondly, embodiments of this application provide a control method for an air conditioning system. This method, applied to an air conditioning system, includes: acquiring a first discharge pressure value of the compressor at a first moment using a pressure sensor; determining a maximum target pressure value from a first target pressure value and a second target pressure value, wherein the first target pressure value is the target discharge pressure value of the compressor when the first indoor unit among a plurality of indoor units operates in a first mode, and the second target pressure value is the target discharge pressure value of the compressor when the second indoor unit among a plurality of indoor units operates in a second mode; and adjusting the speed of the outdoor fan based on the difference between the maximum target pressure value and the first discharge pressure value, so that the discharge pressure value of the compressor reaches the maximum target pressure value.

[0015] Thirdly, embodiments of this application provide a controller, including: one or more processors; one or more memories; wherein the one or more memories are used to store computer program code, the computer program code including computer instructions, and when the one or more processors execute the computer instructions, the controller executes any of the air conditioning system control methods provided in the second aspect.

[0016] Fourthly, embodiments of this application provide a computer-readable storage medium including computer instructions that, when executed on a computer, cause the computer to perform any of the air conditioning system control methods provided in the second aspect.

[0017] Fifthly, embodiments of the present invention provide a computer program product that can be directly loaded into a memory and contains software code. After being loaded and executed by a computer, the computer program product can realize any of the air conditioning system control methods provided in the second aspect.

[0018] It should be noted that the aforementioned computer instructions may be stored, in whole or in part, on a computer-readable storage medium. This computer-readable storage medium may be packaged together with the controller's processor, or it may be packaged separately from the controller's processor; this application does not impose any limitations on this.

[0019] The detailed descriptions of the second to fifth aspects and their various embodiments in this application can be found in the detailed descriptions of the first aspect and its various embodiments; and the beneficial effects of the second to fifth aspects and their various implementations can be found in the beneficial effect analysis of the first aspect and its various embodiments, which will not be repeated here. Attached Figure Description

[0020] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of the present invention and do not constitute a limitation on the technical solutions of the present invention.

[0021] Figure 1 A schematic diagram of the main components of an air conditioning system provided in an embodiment of this application;

[0022] Figure 2 A flowchart of a control method for an air conditioning system provided in an embodiment of this application;

[0023] Figure 3 A flowchart illustrating another control method for an air conditioning system provided in this application embodiment;

[0024] Figure 4 A flowchart illustrating another control method for an air conditioning system provided in this application embodiment;

[0025] Figure 5 A flowchart illustrating another control method for an air conditioning system provided in this application embodiment;

[0026] Figure 6 A logic flowchart of a control method for an air conditioning system provided in an embodiment of this application;

[0027] Figure 7 This is a hardware configuration block diagram of an air conditioning system controller provided in an embodiment of this application. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and 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 this invention.

[0030] The terms "first" and "second" 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" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "multiple" means two or more.

[0031] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "connected" and "linked" should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. Furthermore, when describing pipelines, the terms "connected" and "linked" as used in this application have the meaning of establishing electrical connection. The specific meaning needs to be understood in conjunction with the context.

[0032] In related technologies, air conditioners use the temperature and humidity of the space where the indoor unit is located to adjust the compressor's operating frequency, the opening of the electronic expansion valve, and the speed of the indoor unit's fan to control the refrigerant flow and the indoor unit's outlet air temperature, thus achieving variable frequency control and changing the temperature and humidity of the space where the indoor unit is located. However, when the difference between indoor temperature and humidity is large and there are no fixed target values ​​for temperature and humidity, the compressor may operate at a fixed frequency, causing users to experience a problem where the humidity does not decrease but the perceived temperature is too low.

[0033] Based on this, this application provides a control method for an air conditioning system, which enables dual control of the room temperature and humidity of multiple indoor units through the air conditioning system.

[0034] To facilitate understanding, we will first provide a brief introduction and explanation of some terms or basic concepts of technology involved in the embodiments of the present invention.

[0035] Cooling mode: The air conditioning system's compressor draws the low-temperature, low-pressure gaseous refrigerant, evaporated in the evaporator, into the compressor chamber, compressing it into a high-temperature, high-pressure gaseous refrigerant, which then enters the condenser. In the condenser, the high-temperature, high-pressure gaseous refrigerant condenses into a high-temperature, high-pressure liquid refrigerant. After passing through a throttling element such as a capillary tube, it becomes a low-temperature, low-pressure liquid refrigerant, which then evaporates in the evaporator before finally returning to the compressor, thus completing the entire refrigeration cycle. In cooling mode, the outdoor heat exchanger functions as the condenser, and the indoor heat exchanger functions as the evaporator.

[0036] Heating Mode: When the air conditioner is in heating mode, the refrigerant is pressurized by the compressor, becoming a high-temperature, high-pressure gas. This gas enters the heat exchanger (which acts as the condenser) of the indoor unit, where it condenses and releases heat, becoming a liquid. Simultaneously, it heats the indoor air, thus raising the indoor temperature. The liquid refrigerant is then depressurized by a throttling device and enters the heat exchanger (which acts as the evaporator) of the outdoor unit. There, it evaporates and absorbs heat, becoming a gas, while simultaneously absorbing heat from the outdoor air (making the outdoor air colder). The gaseous refrigerant then re-enters the compressor to begin the next cycle.

[0037] Refrigerant: A substance that easily absorbs heat and turns into a gas, and easily releases heat and turns into a liquid. In air conditioning systems, heat energy is transferred through the evaporation and condensation of the refrigerant to produce a cooling effect.

[0038] Expansion valve: Composed of a valve body and a coil, it is used for throttling and pressure reduction and for regulating flow. In an air conditioning system, the expansion valve allows medium-temperature, high-pressure liquid refrigerant to be throttled into low-temperature, low-pressure wet vapor. The refrigerant then absorbs heat in the evaporator to achieve a cooling effect, and the valve flow is controlled by the change in superheat at the evaporator outlet.

[0039] The embodiments provided in this application will now be described in detail with reference to the accompanying drawings.

[0040] like Figure 1 As shown, this application embodiment provides an air conditioning system and an air conditioning system operation mode control method. The air conditioning system may include an outdoor unit and two or more indoor units, as well as a controller for controlling each indoor unit and the outdoor unit. Figure 1 (Not shown in the image).

[0041] The outdoor unit includes: compressor 1, outdoor heat exchanger 2, outdoor fan 3, outdoor expansion valve 4, four-way reversing valve 5, liquid-side shut-off valve 6, and gas-side shut-off valve 7.

[0042] The outdoor unit of an air conditioning system refers to the part of the refrigeration cycle that includes the compressor and the outdoor heat exchanger. The indoor unit of an air conditioning system includes the indoor heat exchanger, and the expansion valve can be provided in either the indoor or outdoor unit.

[0043] In cooling mode, compressor 1 compresses the refrigerant gas under high temperature and pressure and discharges the compressed refrigerant gas. The refrigerant discharged by compressor 1 flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and heat is released to the surrounding environment through the condensation process.

[0044] Furthermore, in cooling mode, the outdoor expansion valve 4 expands the high-temperature, high-pressure liquid refrigerant condensed in the condenser into a low-pressure liquid refrigerant. The evaporator evaporates the refrigerant that has expanded in the electronic expansion valve, returning the low-temperature, low-pressure refrigerant gas to the compressor. The evaporator achieves a cooling effect by utilizing the latent heat of refrigerant evaporation to exchange heat with the material being cooled. Throughout the cycle, the air conditioning system regulates the temperature of the indoor space.

[0045] The first indoor unit includes: an indoor expansion valve 8, an expansion valve 11, a heat exchanger 10, a heat exchanger 15, a first fan assembly 12, a temperature sensor 9 for the first indoor unit, an air inlet temperature sensor 13 for the first indoor unit, a temperature sensor 14 for the first indoor unit, and a temperature sensor 16 for the first indoor unit.

[0046] The second indoor unit includes: expansion valve 17, expansion valve 20, heat exchanger 19, heat exchanger 24, second fan assembly 21, temperature sensor 18 of the second indoor unit, air inlet temperature sensor 22 of the second indoor unit, temperature sensor 23 of the second indoor unit, and temperature sensor 25 of the second indoor unit.

[0047] The embodiments provided in this application will now be described in detail with reference to the accompanying drawings.

[0048] like Figure 2 As shown in the embodiment of this application, a control method for an air conditioning system is provided. Optionally, this method is... Figure 1 The controller shown executes a method that includes the following steps:

[0049] S101. Obtain the first discharge pressure value of the compressor at the first moment through the pressure sensor.

[0050] The first moment mentioned above refers to any moment during which the air conditioning system is in operation.

[0051] For example, the first moment can be the moment when the air conditioning system starts to run. When the user turns on the air conditioning system, the controller can execute the above step S101 based on the operating mode selected by the user to obtain the first discharge pressure value of the compressor at the first moment in order to control the air conditioning system.

[0052] Furthermore, the aforementioned first exhaust pressure value is as described above. Figure 1 The compressor's discharge pressure value detected at the first moment.

[0053] The exhaust pressure value refers to the pressure of the refrigerant gas in the exhaust pipe at the compressor outlet.

[0054] S102. Determine the maximum target pressure value from the first target pressure value and the second target pressure value.

[0055] The first target pressure value is the target discharge pressure value of the compressor when the first indoor unit among the multiple indoor units is operating in the first mode. The second target pressure value is the target discharge pressure value of the compressor when the second indoor unit among the multiple indoor units is operating in the second mode.

[0056] Optionally, both the first and second modes can be temperature-controlled dehumidification modes. Alternatively, the first mode can be a temperature-controlled dehumidification mode, and the second mode can be a cooling mode.

[0057] For example, with Figure 1 Taking the air conditioning system in the example, when the first mode is temperature control and dehumidification mode and the second mode is cooling mode, the controller of the air conditioning system controls the first indoor heat exchanger of the first indoor unit to work as a condenser, the second indoor heat exchanger of the first indoor unit to work as an evaporator, and controls the third and fourth indoor heat exchangers of the second indoor unit to work as evaporators.

[0058] Alternatively, when both the first mode and the second mode are temperature control and dehumidification modes, the first indoor heat exchanger of the first indoor unit works as a condenser, and the second indoor heat exchanger of the first indoor unit works as an evaporator.

[0059] Optionally, when both the first mode and the second mode are heating modes, the first indoor heat exchanger of the first indoor unit operates as a condenser, the second indoor heat exchanger of the first indoor unit operates as a condenser, and the third and fourth indoor heat exchangers of the second indoor unit both operate as condensers.

[0060] Optionally, when both the first mode and the second mode are in cooling mode, the first indoor heat exchanger and the second indoor heat exchanger of the first indoor unit operate as evaporators, and the third indoor heat exchanger and the fourth indoor heat exchanger of the second indoor unit also operate as evaporators.

[0061] In one possible implementation, when the first target pressure value is greater than or equal to the second target pressure value, the controller determines the first target pressure value as the aforementioned maximum target pressure value.

[0062] In another possible implementation, when the first target pressure value is less than the second target pressure value, the second target pressure value is determined as the aforementioned maximum target pressure value.

[0063] S103. Based on the difference between the maximum target pressure value and the first discharge pressure value, adjust the speed of the outdoor fan so that the discharge pressure value of the compressor reaches the maximum target pressure value.

[0064] Specifically, during the initial operation of the air conditioning system, the controller assigns an initial wind speed value to the outdoor fan 3 based on the outdoor ambient temperature and compressor frequency. It should be understood that the indoor unit has a fixed target pressure value Pdset0 during cooling mode, for example, Pdset0 = 2.9 MPa.

[0065] In some embodiments, since there is a certain deviation between the exhaust pressure Pd and the target pressure value Pdset0, the pressure deviation value is obtained according to ΔPd2 = Pdset0 - Pd. The pressure deviation value and the windshield change value are shown in Table 1. The system determines which pressure deviation range the deviation ΔPd2 falls within, and adjusts the windshield of the outdoor unit fan assembly 3 according to the corresponding windshield change value. Through continuous iterative calculation, Pd is eventually made equal to Pdset0, completing the windshield adjustment of the outdoor unit fan assembly. The controller can determine the difference between the maximum target pressure value and the first exhaust pressure value, and according to this difference and a preset correspondence table, find the required fan speed adjustment value for the outdoor fan in the preset correspondence table. Then, based on the found speed adjustment value, the outdoor fan speed is adjusted from the initial windshield value to ensure that the compressor's exhaust pressure reaches the maximum target pressure value.

[0066] The preset correspondence table includes at least one difference between the maximum target pressure value and the first exhaust pressure value, and at least one fan speed adjustment value of an outdoor fan. Furthermore, the difference between the maximum target pressure value and the first exhaust pressure value corresponds to the fan speed adjustment value of the at least one outdoor fan.

[0067] Optionally, when both the first mode and the second mode are in cooling mode, the above-mentioned preset correspondence table is shown in Table 1. Here, ΔPd2 is the difference between the maximum target pressure value and the first exhaust pressure value when both the first mode and the second mode are in cooling mode.

[0068] For example, if the difference between the determined maximum target pressure value and the first exhaust pressure value is -0.9, then based on the difference of -0.9 and Table 1 below, it can be determined that the outdoor fan needs to be adjusted to a fan speed of +3. In this case, the outdoor fan speed will be increased by 3 levels.

[0069] For example, if the difference between the determined maximum target pressure value and the first exhaust pressure value is 0.4, then based on the difference of 0.4 and Table 1 below, it can be determined that the fan speed adjustment value of the outdoor fan needs to be -1. In this case, the fan speed of the outdoor fan will be lowered by 1 level.

[0070] Table 1

[0071] ΔPd2 Fan speed adjustment value ΔPd2 < -0.8 +3 -0.8≤ΔPd2<-0.5 +2 -0.5≤ΔPd2<-0.1 +1 -0.1≤ΔPd2<0.1 0 0.1 ≤ ΔPd² < 0.5 -1 0.5 ≤ ΔPd² < 0.8 -2 ΔPd2≥0.8 -3

[0072] Optionally, when both the first and second modes are heating modes, the air conditioning system may also include another preset correspondence table. When both the first and second indoor units start operating in heating mode, the first indoor heat exchanger of the first indoor unit operates as a condenser, the second indoor heat exchanger of the first indoor unit operates as a condenser, and the third and fourth indoor heat exchangers of the second indoor unit both operate as condensers.

[0073] Optionally, when the first indoor unit operates in temperature-controlled dehumidification mode and the second indoor unit operates in cooling mode, the above-mentioned preset correspondence table is shown in Table 2. Here, ΔT is the temperature difference between the return air temperature and the set temperature when the first indoor unit operates in temperature-controlled dehumidification mode and the second indoor unit operates in cooling mode, and x refers to the rate of change of the temperature difference between the current period and the previous period, with a certain detection time as a cycle. ΔPd2 is the difference between the maximum target pressure value and the first exhaust pressure value when the first indoor unit operates in temperature-controlled dehumidification mode and the second indoor unit operates in cooling mode.

[0074] For example, if the difference between the determined maximum target pressure value and the first exhaust pressure value is -1, then based on the difference of -1 and Table 2 below, it can be determined that the fan speed adjustment value of the outdoor fan needs to be +3. In this case, the fan speed of the outdoor fan will be increased by 3 levels.

[0075] For example, if the difference between the determined maximum target pressure value and the first exhaust pressure value is 0.3, then based on the difference of 0.3 and Table 2 below, it can be determined that the fan speed adjustment value of the outdoor fan needs to be -1. In this case, the fan speed of the outdoor fan will be lowered by 1 level.

[0076] Table 2

[0077] ΔPd2 Fan speed adjustment value ΔPd2 < -0.8 +3 -0.8 ≤ ΔPd² < -0.5 +2 -0.5≤ΔPd2<-0.1 +1 -0.1≤ΔPd2<0.1 0 0.1 ≤ ΔPd² < 0.5 -1 0.5 ≤ ΔPd² < 0.8 -2 ΔPd2≥0.8 -3

[0078] Optionally, when the first indoor unit, the second indoor unit, or more indoor units operate in a temperature-controlled dehumidification mode with different set temperatures, the above-mentioned preset correspondence table is shown in Table 3. Here, ΔT is the temperature difference between the return air temperature and the set temperature when the first indoor unit, the second indoor unit, or more indoor units operate in a temperature-controlled dehumidification mode with different set temperatures; x refers to the rate of change of the temperature difference between the current period and the previous period, with a certain detection time as a cycle. ΔPd2 is the difference between the maximum target pressure value and the first exhaust pressure value when the first indoor unit, the second indoor unit, or more indoor units operate in a temperature-controlled dehumidification mode with different set temperatures.

[0079] Table 3

[0080] ΔPd2 Fan speed adjustment value ΔPd2 < -0.8 +3 -0.8≤ΔPd2<-0.5 +2 -0.5≤ΔPd2<-0.1 +1 -0.1≤ΔPd2<0.1 0 0.1 ≤ ΔPd² < 0.5 -1 0.5 ≤ ΔPd² < 0.8 -2 ΔPd2≥0.8 -3

[0081] Optionally, when the compressor's discharge pressure is equal to the maximum target pressure value, or when the difference between the compressor's discharge pressure and the maximum target pressure value is less than a certain pressure threshold, the controller can determine that the compressor's discharge pressure has reached the maximum target pressure value.

[0082] Alternatively, if the compressor's discharge pressure is close to the maximum target pressure, for example, if the difference between the compressor's discharge pressure and the maximum target pressure is less than a preset threshold, the controller can determine that the maximum target pressure has reached the compressor's discharge pressure. The preset threshold can be a relatively small preset pressure value.

[0083] The technical solution provided in this application provides at least the following beneficial effects: The outdoor unit of the air conditioning system assigns an initial wind speed value to the outdoor fan based on the indoor ambient temperature and compressor frequency, thus obtaining the corresponding initial exhaust pressure value. The corresponding indoor ambient temperature is obtained from the inlet air temperature sensor. If the ambient temperatures of the two indoor units are different, and the set temperatures of the two temperature-controlled and dehumidifying indoor units are also different, the change value of the target pressure is obtained based on the temperature difference between the return air temperature and the set temperature, and the rate of change of the temperature difference. This determines the target value of the exhaust pressure for the next step, ultimately achieving consistency between the indoor unit ambient temperature and the set temperature. This improves the efficiency of setting the air conditioning system for users and optimizes the user experience.

[0084] Optional, such as Figure 3 As shown, when the first mode is temperature control and dehumidification mode and the second mode is cooling mode, step S103 can be specifically implemented as follows:

[0085] S103A1: The second exhaust pressure value of the compressor at the second moment is obtained through the pressure sensor, and the first return air temperature is obtained through the first temperature sensor.

[0086] The first temperature sensor is the temperature sensor in the first indoor unit, and the second moment is the moment after the first moment.

[0087] It should be noted that the second exhaust pressure value at the second moment obtained by the pressure sensor is compared with the first exhaust pressure value. If the two values ​​are equal, no further iterative calculation is required. If they are not equal, S103A2 continues.

[0088] S103A2, if the second exhaust pressure value and the first target pressure value do not reach the maximum target pressure value among the second target pressure values, the first target pressure value is adjusted according to the difference between the first return air temperature and the preset temperature of the first indoor unit to obtain the third target pressure value.

[0089] The third target pressure value is the target pressure value at the second moment when the first indoor unit is running in the first mode.

[0090] Optionally, when the first indoor unit operates in temperature-controlled dehumidification mode, the first target pressure value changes. Furthermore, the controller can obtain the initial return air temperature at a first moment and the first return air temperature at a second moment through the first temperature sensor; based on the first temperature difference between the first return air temperature and the preset temperature of the first indoor unit, and the rate of change of the temperature difference of the first indoor unit at the second moment, the first target pressure value is adjusted, wherein the rate of change of the temperature difference is the change between the first temperature difference and the initial temperature difference, and the initial temperature difference is the temperature difference between the initial return air temperature and the preset temperature of the first indoor unit.

[0091] For example, the change in the first target pressure value is shown in Formula 1:

[0092] Pdset1(n+1)=ΔPd1+Pdset1(n) Formula 1

[0093] Wherein, Pdset1(n+1) is the target value of exhaust pressure in the (n+1)th calculation, Pdset1(n) is the target value of exhaust pressure in the nth calculation, and ΔPd1 is the difference between Pdset1(n) and Pdset1(n+1).

[0094] It should be understood that if the first target pressure value at the first moment is Pdset1(n), then the third target pressure value at the second moment is the target pressure value Pdset1(n+1) obtained according to Formula 1 above.

[0095] Optionally, the target pressure change value ΔPd1 in Formula 1 above can be determined based on the temperature difference ΔT between the return air temperature and the set temperature, and the temperature difference change rate x. Then, by combining the determined ΔPd1 with Formula 1, the target value of the exhaust pressure at the second moment can be determined.

[0096] The temperature difference change rate X is the rate of change of the temperature difference between the return air temperature and the set temperature in two consecutive calculations. The temperature difference change rate X can be determined according to the following formula 2:

[0097] x= (Ti(n+1)-Ts)+(Ti(n)-Ts) Formula 2

[0098] Where Ti(n+1) represents the return air temperature detected in the (n+1)th calculation, Ti(n) represents the return air temperature detected in the nth calculation, and Ts represents the set temperature. Optionally, the correspondence between the temperature difference ΔT, the rate of change of temperature difference x, and the change in target pressure ΔPd1 can be shown in Table 4:

[0099] Table 4

[0100]

[0101] For example, if the target pressure value Pdset1 of the first indoor unit is 5 MPa, the temperature difference ΔT between the return air temperature and the set temperature is -4℃, and the temperature difference change rate x is -0.7℃, then based on -4℃, -0.7℃ and Table 4 above, we can obtain ΔPd1 = 0.5 MPa, and determine that the target value Pdset1(n+1) of the third exhaust pressure at the second moment is 5 MPa + 0.5 MPa = 5.5 MPa.

[0102] For example, if the target pressure value Pdset1 of the first indoor unit is 12 MPa, the temperature difference ΔT between the return air temperature and the set temperature is 2℃, and the temperature difference change rate x is 0.3℃, then based on 2℃, 0.3℃ and Table 4 above, we can obtain ΔPd1 = -0.2 MPa, and determine that the target value Pdset1(n+1) of the third exhaust pressure at the second moment is 12 MPa + (-0.2 MPa) = 11.8 MPa.

[0103] In some embodiments, if the second exhaust pressure value and the first target pressure value reach the maximum target pressure value among the second target pressure values, it is not necessary to adjust the speed of the outdoor fan at a second moment.

[0104] S103A3: Based on the difference between the third target pressure value and the second exhaust pressure value, adjust the speed of the outdoor fan so that the exhaust pressure value of the compressor reaches the third target pressure value.

[0105] In some embodiments, such as Figure 1 As shown, when both the first and second indoor units are in cooling operation mode, the refrigerant first flows from the compressor 1 to the outdoor unit heat exchanger 2, and then flows to the indoor unit through the liquid-side shut-off valve 6. The expansion valves 11 and 20 in the indoor unit are both fully open. The heat exchangers 10, 15, 19, and 24 in the first and second heat exchange units are all evaporators. The corresponding liquid pipe temperature T1 and gas pipe temperature Tg are obtained through the liquid pipe temperature sensors 9 and 18 and the gas pipe temperature sensors 16 and 25, and then the corresponding superheat = Tg - T1 is obtained. The superheat of the indoor unit is controlled by adjusting the opening of the expansion valves 8 and 17, thereby controlling the capacity of the indoor unit.

[0106] Furthermore, the controller can look up the preset correspondence table, such as Table 2, based on the difference between the third target pressure value and the second exhaust pressure value.

[0107] For example, if the difference between the determined maximum target pressure value and the first exhaust pressure value is 0, then based on the difference of 0 and Table 2 above, it can be determined that the fan speed adjustment value of the outdoor fan needs to be 0. In this case, the fan speed of the outdoor fan does not need to be adjusted, and the fan speed of the outdoor fan after the first moment of adjustment is maintained.

[0108] For example, if the difference between the determined maximum target pressure value and the first exhaust pressure value is 0.7, then based on the difference of 0.7 and Table 2 above, the required fan speed adjustment value for the outdoor fan can be determined to be -2. In this case, the fan speed of the outdoor fan will be lowered by 2 levels. If the adjusted fan speed of the outdoor fan is level 2 in the first moment, then the controller can adjust the fan speed to level 0 in the second moment.

[0109] It should be noted that for the second indoor unit operating in cooling mode, both expansion valve 20 and expansion valve 17 are kept at their maximum opening.

[0110] Based on the above embodiments, the target exhaust pressure value set for the first indoor unit operating in temperature-controlled dehumidification mode can be varied. The controller can adjust the target pressure value based on the environmental conditions of the first indoor unit, such as the temperature difference between the return air temperature and the set temperature, and the rate of change of the temperature difference, so that the redefined target pressure value is more in line with the current environmental conditions of the first indoor unit. Furthermore, compared to the commonly used cooling and dehumidification mode of air conditioners, the temperature-controlled dehumidification mode provided in this application can achieve dual control of room temperature and humidity. It can control the required indoor ambient temperature without causing the ambient temperature to be too low, while also reducing the indoor humidity to meet the user's comfort needs.

[0111] Optional, such as Figure 4 As shown, when both the first mode and the second mode are temperature-controlled dehumidification modes, step S103 can be further implemented as follows:

[0112] S103B1. When the compressor's discharge pressure value does not reach the maximum target pressure value, the first target pressure value is adjusted according to the difference between the first return air temperature and the preset temperature of the first indoor unit to obtain the third target pressure value, and the second target pressure value is adjusted according to the difference between the second return air temperature and the preset temperature of the second indoor unit to obtain the fourth target pressure value.

[0113] Optionally, the controller can determine the change in target pressure corresponding to the first indoor unit based on the difference between the first return air temperature and the preset temperature of the first indoor unit, in conjunction with Table 4. Then, using Formula 1 above, the third target pressure value can be determined.

[0114] Similarly, the controller can also determine the target pressure change value corresponding to the second indoor unit based on the difference between the second return air temperature and the preset temperature of the second indoor unit, in conjunction with Table 4. Then, by combining this with Formula 1 above, the fourth target pressure value can be determined.

[0115] The specific process by which the controller determines the third and fourth target pressure values ​​in conjunction with Table 4 and Formula 1 can be found in the relevant description in step S103A2 above, and will not be repeated here.

[0116] S103B2, Adjust the speed of the outdoor fan based on the difference between the maximum target pressure value between the third and fourth target pressure values ​​and the second exhaust pressure value.

[0117] Specifically, the controller can first determine the gear adjustment value of the outdoor fan based on the difference between the maximum target pressure value between the third and fourth target pressure values ​​and the second exhaust pressure value, and then adjust the gear of the outdoor fan based on the gear adjustment value.

[0118] Optionally, the correspondence between the differences between the above pressure values ​​and the fan speed adjustment value of the outdoor fan can be as shown in Table 3 above.

[0119] The specific adjustment process for the outdoor fan speed can be found in the relevant description in step S103 above, and will not be repeated here.

[0120] Based on the above embodiments, when both indoor units are operating in temperature-controlled dehumidification mode, the corresponding indoor ambient temperature (the aforementioned return air temperature) can be obtained from the inlet air temperature sensor. If the ambient temperatures of the two indoor units are different, and the set temperatures of the two temperature-controlled dehumidification indoor units are also different, the change value of the target pressure is obtained based on the temperature difference and the rate of change of the temperature difference between the return air temperature and the set temperature. This allows for the confirmation of the target value of the exhaust pressure in the next step, ultimately achieving consistency between the indoor unit ambient temperature and the set temperature. This improves the efficiency of setting the air conditioning system for users and optimizes the user experience.

[0121] Optional, such as Figure 5 As shown, when both the first and second modes are temperature control and dehumidification modes, the control method may further include the following steps:

[0122] S201. Obtain the second exhaust pressure value, the first return air temperature, and the second return air temperature.

[0123] The second exhaust pressure value is obtained by acquiring the pressure value detected by the compressor at the second moment through a pressure sensor, and the first return air temperature is obtained through a first temperature sensor, and the second return air temperature is obtained through a second temperature sensor.

[0124] Optionally, the first return air temperature and the second return air temperature can be the same indoor ambient temperature, that is, the first return air temperature and the second return air temperature can be equal.

[0125] Furthermore, the second moment is the moment following the first moment.

[0126] S202. When the compressor's discharge pressure reaches the maximum target pressure, if the first target pressure is greater than or equal to the second target pressure, adjust the opening of the second expansion valve according to the saturation pressure corresponding to the second target pressure and the second return air temperature.

[0127] Among them, such as Figure 1 As shown, the second expansion valve can be the expansion valve 17 of the second indoor unit.

[0128] Optionally, when the compressor's discharge pressure is greater than the saturation pressure corresponding to the second return air temperature, the opening of the second expansion valve is reduced. Alternatively, when the compressor's discharge pressure is less than the saturation pressure corresponding to the second return air temperature, the opening of the second expansion valve is increased.

[0129] This ensures that the saturation pressure value corresponding to the return air temperature of the second indoor unit reaches the discharge pressure value of the compressor. It should be understood that when the second target pressure value is equal to the saturation pressure value corresponding to the second return air temperature, the controller can determine that the saturation pressure value corresponding to the return air temperature of the second indoor unit has reached the discharge pressure value of the compressor.

[0130] Alternatively, if the compressor's discharge pressure is close to the saturation pressure corresponding to the second return air temperature—for example, if the difference between the compressor's discharge pressure and the saturation pressure corresponding to the second return air temperature is less than a preset threshold—the controller can determine that the saturation pressure corresponding to the return air temperature of the second indoor unit has reached the compressor's discharge pressure. The preset threshold can be a relatively small preset pressure value.

[0131] S203. If the first target pressure value is less than the second target pressure value, adjust the opening of the first expansion valve according to the saturation pressure value corresponding to the first target pressure value and the first return air temperature.

[0132] Among them, such as Figure 1 As shown, the first expansion valve can be the expansion valve 8 of the first indoor unit.

[0133] Optionally, when the compressor's discharge pressure is greater than the saturation pressure corresponding to the first return air temperature, the opening of the first expansion valve is reduced. Alternatively, when the compressor's discharge pressure is less than the saturation pressure corresponding to the first return air temperature, the opening of the first expansion valve is increased.

[0134] This ensures that the saturation pressure value corresponding to the return air temperature of the first indoor unit reaches the discharge pressure value of the compressor. It should be understood that when the compressor's discharge pressure value is equal to the saturation pressure value corresponding to the first return air temperature, the controller can determine that the saturation pressure value corresponding to the return air temperature of the first indoor unit has reached the compressor's discharge pressure value.

[0135] Alternatively, if the compressor's discharge pressure is close to the saturation pressure corresponding to the first return air temperature—for example, if the difference between the compressor's discharge pressure and the saturation pressure corresponding to the first return air temperature is less than a preset threshold—the controller can determine that the saturation pressure corresponding to the return air temperature of the second indoor unit has reached the compressor's discharge pressure. The preset threshold can be a relatively small preset pressure value.

[0136] In some embodiments, in conjunction with the above Figure 4 and Figure 5 The air conditioning system control method provided in this application embodiment can also be described as follows: Figure 6 The logic flowchart shown is as follows. Figure 6 As shown, after the air conditioning system starts running, the controller can perform the following steps: S1, obtain the first return air temperature Ti1, the second return air temperature Ti2 and the set temperature Ts.

[0137] S2. Determine Pdset1 and Pdset2.

[0138] The controller can find the target pressure value change ΔPd1 in Table 4 above based on the temperature difference (Ti1-Ts) and temperature difference change rate of the first indoor unit, and determine the target pressure value Pdset1 of the first indoor unit in the next calculation cycle by combining it with Formula 1 above.

[0139] Furthermore, the controller can find the target pressure value change ΔPd2 in Table 4 above based on the temperature difference (Ti2-Ts) and temperature difference change rate of the second indoor unit, and determine the target pressure value Pdset2 of the second indoor unit for the next calculation cycle in combination with Formula 1 above.

[0140] S3. When Pdset1 > Pdset2, use Pdset1 as the pressure value adjustment target and adjust the speed of the outdoor fan based on Pdset1.

[0141] If the compressor's discharge pressure does not reach the maximum target pressure, repeat step S3 until the compressor's discharge pressure reaches the Pdset1 value.

[0142] S4. When the compressor's discharge pressure reaches the value of Pdset1, if the compressor's discharge pressure Pd is greater than the saturation pressure value corresponding to the ambient temperature Pd2 of the second indoor unit, reduce the opening of the expansion valve 17.

[0143] S5. If Pd is less than Pd2, increase the opening of expansion valve 17.

[0144] If the compressor's discharge pressure does not reach the saturation pressure value corresponding to the ambient temperature of the second indoor unit, i.e., Pd≠Pd2, repeat steps S4 and / or S5 until the compressor's discharge pressure reaches the maximum target pressure value.

[0145] The adjustment task ends when the compressor's discharge pressure reaches the saturation pressure corresponding to the ambient temperature of the second indoor unit, i.e., Pd = Pd2.

[0146] S6. When Pdset1 < Pdset2, take Pdset2 as the pressure value adjustment target and adjust the speed of the outdoor fan based on Pdset2.

[0147] If the compressor's discharge pressure does not reach the maximum target pressure, repeat step S6 until the compressor's discharge pressure reaches the Pdset2 value.

[0148] S7. When the compressor's discharge pressure reaches the value of Pdset2, if the compressor's discharge pressure Pd is greater than the saturation pressure value Pd1 corresponding to the ambient temperature of the first indoor unit, reduce the opening of the expansion valve 8.

[0149] S8. If Pd is less than Pd1, increase the opening of expansion valve 8.

[0150] If the compressor's discharge pressure does not reach the saturation pressure value corresponding to the ambient temperature of the first indoor unit, i.e., Pd≠Pd1, repeat steps S7 and / or S8 until the compressor's discharge pressure reaches the maximum target pressure value.

[0151] The adjustment task ends when the compressor's discharge pressure reaches the saturation pressure corresponding to the ambient temperature of the second indoor unit, i.e., Pd = Pd1.

[0152] As can be seen, the above mainly describes the solutions provided by the embodiments of this application from a methodological perspective. To achieve the above functions, the embodiments of this application provide corresponding hardware structures and / or software modules for executing each function. Those skilled in the art should readily recognize that, in conjunction with the modules and algorithm steps of the various examples described in the embodiments disclosed herein, the embodiments of this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed by hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this invention.

[0153] This application embodiment can divide the controller into functional modules according to the above method example. For example, each function can be divided into a separate functional module, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware or as a software functional module. Optionally, the module division in this application embodiment is illustrative and only represents one logical functional division; other division methods may be used in actual implementation.

[0154] This application also provides a hardware structure diagram of a controller, such as... Figure 7 As shown, the controller 1000 includes a processor 1001, and optionally, a memory 1002 and a communication interface 1003 connected to the processor 1001. The processor 1001, memory 1002 and communication interface 1003 are connected via a bus 1004.

[0155] Processor 1001 may be a central processing unit (CPU), a general-purpose processor, a network processor (NP), a digital signal processor (DSP), a microprocessor, a microcontroller, a programmable logic device (PLD), or any combination thereof. Processor 1001 may also be any other device with processing capabilities, such as a circuit, device, or software module. Processor 1001 may also include multiple CPUs, and processor 1001 may be a single-core processor or a multi-core processor. Here, "processor" can refer to one or more devices, circuits, or processing cores used to process data (e.g., computer program instructions).

[0156] The memory 1002 may be a read-only memory (ROM) or other type of static storage device capable of storing static information and instructions, random access memory (RAM) or other type of dynamic storage device capable of storing information and instructions, or it may be an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer. This application embodiment does not impose any limitations on this. The memory 1002 may exist independently or may be integrated with the processor 1001. The memory 1002 may contain computer program code. The processor 1001 is used to execute the computer program code stored in the memory 1002, thereby implementing the air conditioning system control method provided in this application embodiment.

[0157] The communication interface 1003 can be used to communicate with other devices or communication networks (such as Ethernet, radio access network (RAN), wireless local area network (WLAN), etc.). The communication interface 1003 can be a module, circuit, transceiver, or any device capable of enabling communication.

[0158] Bus 1004 can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. Bus 1004 can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 7 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0159] This invention also provides a computer-readable storage medium, which includes computer-executable instructions. When the computer-executable instructions are executed on the computer, the computer performs a control method for an air conditioning system as provided in the above embodiments.

[0160] This invention also provides a computer program product that can be directly loaded into a memory and contains software code. After being loaded and executed by a computer, the computer program product can realize the control method of an air conditioning system provided in the above embodiments.

[0161] Those skilled in the art will recognize that, in one or more of the examples above, the functions described in this invention can be implemented using hardware, software, firmware, or any combination thereof. When implemented in software, these functions can be stored in a computer-readable medium or transmitted as one or more instructions or code on a computer-readable medium. Computer-readable media include computer storage media and communication media, wherein communication media include any medium that facilitates the transfer of a computer program from one place to another. Storage media can be any available medium accessible to a general-purpose or special-purpose computer.

[0162] Through the above description of the embodiments, those skilled in the art can clearly understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0163] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and other division methods may exist in actual implementation. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms. Units described as separate components may or may not be physically separate; components shown as units may be one physical unit or multiple physical units, i.e., they may be located in one place or distributed in multiple different places. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0164] Furthermore, the functional units in the various embodiments of this invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solution of the embodiments of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This software product is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0165] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An air conditioning system, characterized in that, include: Outdoor fan; Multiple indoor units; compressor; A pressure sensor is used to detect the discharge pressure value of the compressor; A first temperature sensor is used to detect the return air temperature of the first indoor unit among the plurality of indoor units; The second temperature sensor is used to detect the return air temperature of the second indoor unit among the plurality of indoor units; The first expansion valve is used to regulate the refrigerant flow in the pipeline between the first indoor unit and the outdoor unit. The second expansion valve is used to regulate the refrigerant flow in the pipeline between the second indoor unit and the outdoor unit; The controller is configured as follows: The first discharge pressure value of the compressor at a first moment is obtained through the pressure sensor; The maximum target pressure value is determined from the first target pressure value and the second target pressure value. The first target pressure value is the target discharge pressure value of the compressor when the first indoor unit among the plurality of indoor units is operating in the first mode. The second target pressure value is the target discharge pressure value of the compressor when the second indoor unit among the plurality of indoor units is operating in the second mode. The first mode is a temperature control and dehumidification mode, and the second mode is a cooling mode. Alternatively, it can be switched so that both the first mode and the second mode are temperature control and dehumidification modes. Based on the difference between the maximum target pressure value and the first exhaust pressure value, the speed of the outdoor fan is adjusted so that the exhaust pressure value of the compressor reaches the maximum target pressure value. When both the first mode and the second mode are temperature control and dehumidification modes, the second exhaust pressure value of the compressor at the second moment is obtained through the pressure sensor, and the first return air temperature is obtained through the first temperature sensor, and the second return air temperature is obtained through the second temperature sensor; the second moment is a moment after the first moment. If the second exhaust pressure value reaches the maximum target pressure value, and if the first target pressure value is greater than or equal to the second target pressure value, the opening of the second expansion valve is adjusted according to the second target pressure value and the saturation pressure value at the second return air temperature, so that the saturation pressure value at the return air temperature of the second indoor unit reaches the exhaust pressure value of the compressor. If the first target pressure value is less than the second target pressure value, the opening of the first expansion valve is adjusted according to the first target pressure value and the saturation pressure value at the first return air temperature, so that the saturation pressure value at the return air temperature of the first indoor unit reaches the discharge pressure value of the compressor.

2. The air conditioning system according to claim 1, characterized in that, When the first mode is temperature control and dehumidification mode and the second mode is cooling mode, the first indoor heat exchanger of the first indoor unit works as an evaporator, the second indoor heat exchanger of the first indoor unit works as a condenser, and the third and fourth indoor heat exchangers of the second indoor unit both work as evaporators.

3. The air conditioning system according to claim 2, characterized in that, The air conditioning system also includes: The first temperature sensor is used to detect the return air temperature of the first indoor unit; The controller is also configured to: The initial return air temperature at the first moment and the first return air temperature at the second moment are obtained through the first temperature sensor. The first target pressure value is adjusted based on the first temperature difference between the first return air temperature and the preset temperature of the first indoor unit and the temperature difference change rate of the first indoor unit at the second time point, wherein the temperature difference change rate is the change between the first temperature difference and the initial temperature difference, and the initial temperature difference is the temperature difference between the initial return air temperature and the preset temperature of the first indoor unit.

4. A control method for an air conditioning system, characterized in that, The method, applied to the air conditioning system according to any one of claims 1-3, comprises: The first discharge pressure value of the compressor at the first moment is obtained by the pressure sensor; The maximum target pressure value is determined from the first target pressure value and the second target pressure value. The first target pressure value is the target discharge pressure value of the compressor when the first indoor unit among the plurality of indoor units is operating in a first mode. The second target pressure value is the target pressure value corresponding to the second mode of operation of the second indoor unit among the plurality of indoor units. The first mode is a temperature-controlled dehumidification mode, and the second mode is a cooling mode. Alternatively, it can be switched so that both the first mode and the second mode are temperature-controlled dehumidification modes. Based on the difference between the maximum target pressure value and the first exhaust pressure value, the speed of the outdoor fan is adjusted so that the exhaust pressure value of the compressor reaches the maximum target pressure value. When both the first mode and the second mode are temperature control and dehumidification modes, the second exhaust pressure value of the compressor at the second moment is obtained through the pressure sensor, and the first return air temperature is obtained through the first temperature sensor, and the second return air temperature is obtained through the second temperature sensor; the second moment is a moment after the first moment. If the second exhaust pressure value reaches the maximum target pressure value, and if the first target pressure value is greater than or equal to the second target pressure value, the opening of the second expansion valve is adjusted according to the second target pressure value and the saturation pressure value at the second return air temperature, so that the saturation pressure value at the return air temperature of the second indoor unit reaches the exhaust pressure value of the compressor. If the first target pressure value is less than the second target pressure value, the opening of the first expansion valve is adjusted according to the first target pressure value and the saturation pressure value at the first return air temperature, so that the saturation pressure value at the return air temperature of the first indoor unit reaches the discharge pressure value of the compressor.

5. The method according to claim 4, characterized in that, When the first mode is temperature control and dehumidification mode and the second mode is cooling mode, the first indoor heat exchanger of the first indoor unit works as a condenser, the second indoor heat exchanger of the first indoor unit works as an evaporator, and the third and fourth indoor heat exchangers of the second indoor unit both work as evaporators.

6. The method according to claim 5, characterized in that, The method further includes: The initial return air temperature at the first moment and the first return air temperature at the second moment are obtained by the first temperature sensor. The first target pressure value is adjusted based on the first temperature difference between the first return air temperature and the preset temperature of the first indoor unit and the temperature difference change rate of the first indoor unit at the second time point, wherein the temperature difference change rate is the change between the first temperature difference and the initial temperature difference, and the initial temperature difference is the temperature difference between the initial return air temperature and the preset temperature of the first indoor unit.

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