A multi-split air conditioning system

Abstract

The application relates to a multi-connected air conditioning system, and belongs to the technical field of air conditioners. The multi-connected air conditioning system comprises an outdoor unit, at least two indoor units and a controller. The controller is configured to: when the number of opened indoor units changes, calculate the rated capacity sum of all currently opened indoor units; calculate the frequency change amount of the compressor based on the rated capacity sum, and adjust the operating frequency of the compressor according to the frequency change amount; calculate the frequency change ratio; and according to the frequency change ratio, adjust the opening degree of the outdoor electronic expansion valve and the opening degrees of the indoor electronic expansion valves corresponding to the opened indoor units. The application effectively avoids the refrigerant flow mutation problem caused by the sudden change of the opening degree of the indoor electronic expansion valve in the prior art, enables the system refrigerant flow to dynamically match the load change, and significantly suppresses the sharp fluctuation of the exhaust pressure and temperature in the indoor unit number switching process.

Description

Technical Field

[0001] This application relates to the field of air conditioning technology, and in particular to a multi-split air conditioning system. Background Technology

[0002] A multi-split air conditioning system typically consists of one outdoor unit and multiple indoor units. The outdoor unit includes a compressor, an outdoor heat exchanger, and an outdoor electronic expansion valve, while the indoor units are equipped with indoor heat exchangers and indoor electronic expansion valves. This system achieves independent control of the refrigerant flow in each indoor unit by adjusting the compressor speed and dynamically controlling the opening of each indoor electronic expansion valve, thus flexibly adapting to the dynamic load demands of different rooms. Due to this advantage, multi-split systems are widely used in commercial office buildings, hotels, and high-end residences.

[0003] However, existing multi-split air conditioning systems can only achieve precise control of the indoor electronic expansion valve for a single model of indoor unit, lacking universal adaptability to combinations of multiple indoor unit models. In actual use, however, the same outdoor unit often needs to connect to multiple indoor units of different types, capacities, or specifications. In this situation, when the user changes the number of operating indoor units (e.g., from three to four, or from five to two), the total opening degree of the indoor electronic expansion valve often changes drastically. This drastic change in the total opening degree leads to sudden changes in refrigerant flow, resulting in sharp fluctuations in compressor load, specifically manifested as an abnormally high discharge temperature. Excessively high discharge temperatures may not only trigger the system's high-temperature protection mechanism, leading to unplanned shutdowns and affecting the user experience, but may also accelerate the aging of the compressor lubricating oil, reducing the long-term reliability of the equipment. Summary of the Invention

[0004] This application provides a multi-split air conditioning system, the purpose of which is to effectively solve the problem of excessively high exhaust temperature of outdoor unit compressor caused by sudden changes in the opening of indoor electronic expansion valves during the switching of indoor units in existing systems by adjusting the opening of each indoor electronic expansion valve and coordinating the opening of outdoor electronic expansion valve and compressor operating frequency, thereby ensuring the stability and reliability of system operation.

[0005] To achieve the above objectives, this application adopts the following technical solution: Firstly, a multi-split air conditioning system is provided, comprising: The outdoor unit includes a compressor and an outdoor electronic expansion valve; At least two indoor units, each of which is connected to the outdoor unit via a refrigerant pipeline, and each of the indoor units is equipped with an indoor electronic expansion valve; The controller is configured to: Determine whether the number of currently activated indoor units has changed; If so, then enter adjustment mode; If not, wait for a preset time and then reassess whether the number of currently activated indoor units has changed. Entering the adjustment mode, calculate the total rated capacity of all currently activated indoor units; The frequency change of the compressor is obtained based on the sum of the rated capacities according to the first rule; The operating frequency of the compressor is adjusted according to the frequency change. Calculate the frequency change ratio based on the frequency change amount; Based on the frequency change ratio, the target opening degree of the indoor electronic expansion valve corresponding to each of the activated indoor units is obtained through the second rule, and the target opening degree of the outdoor electronic expansion valve is obtained through the third rule. Control the indoor electronic expansion valves corresponding to each of the already turned-on indoor units to adjust to their respective target opening degrees, and control the outdoor electronic expansion valves to adjust to their target opening degrees.

[0006] Secondly, a multi-split air conditioning system is provided, comprising: Outdoor circuit; The compressor is installed on the outdoor circuit; An outdoor electronic expansion valve is installed on the outdoor circuit and is used to control the opening degree of the outdoor circuit. Several indoor circuits are arranged in parallel, and the indoor circuits are connected to the outdoor circuits. Several indoor electronic expansion valves are installed on the indoor circuit and are used to control the opening degree of the indoor circuit. The controller is configured to: Determine whether the number of currently activated indoor circuits has changed; If so, then enter adjustment mode; If not, wait for a preset time and then reassess whether the number of currently activated indoor circuits has changed. Entering the adjustment mode, calculate the total rated capacity of all currently activated indoor circuits; The frequency change of the compressor is obtained based on the sum of the rated capacities according to the first rule; The operating frequency of the compressor is adjusted according to the frequency change. Calculate the frequency change ratio based on the frequency change amount; Based on the frequency change ratio, the target opening degree of the indoor electronic expansion valve corresponding to each of the activated indoor units is obtained through the second rule, and the target opening degree of the outdoor electronic expansion valve is obtained through the third rule. Control the indoor electronic expansion valves corresponding to each of the already turned-on indoor units to adjust to their respective target opening degrees, and control the outdoor electronic expansion valves to adjust to their target opening degrees.

[0007] In the above embodiments, this application calculates the compressor frequency change based on the total rated capacity of the activated indoor units when the number of indoor units changes, and further calculates the compressor frequency change ratio. This allows for the synchronous adjustment of the compressor's operating frequency, the opening of the outdoor electronic expansion valve, and the opening of the indoor electronic expansion valve corresponding to each activated indoor unit. This constructs a linkage mechanism that precisely allocates the indoor electronic expansion valve opening and coordinates the compressor's operating frequency and the outdoor electronic expansion valve opening. This linkage mechanism effectively avoids the refrigerant flow mutation problem caused by sudden changes in the total opening of the indoor electronic expansion valves in existing technologies. It enables the system refrigerant flow to dynamically match load changes, significantly suppressing drastic fluctuations in exhaust pressure and temperature during room number switching, and specifically addressing the industry pain point of excessively high compressor exhaust temperature in multi-split air conditioning systems under room number switching conditions. Meanwhile, since this application uses the frequency change ratio as a unified correlation parameter to drive the opening adjustment of the indoor and outdoor electronic expansion valves, it does not rely on a specific model or capacity combination of indoor units. This breaks through the limitation of traditional control logic being only applicable to the same type of unit, and significantly improves the system's compatibility and adaptability to different types of indoor units and its operational reliability under complex dynamic conditions.

[0008] In some embodiments, the first rule is:

[0009] in, The frequency change of the compressor is N, where N is a correction factor. This represents the total rated capacity of all currently active indoor units. This is a correction factor for frequency variation. This is the correction factor for the indoor unit when it is turned off.

[0010] In the above embodiments, this application establishes a direct correlation between the compressor's frequency change and the total rated capacity of all currently active indoor units, constructing a dynamic control mechanism that matches the system's current actual operating conditions. Simultaneously, by introducing correction coefficients N, Kc(k), and Kcd(k) for the shut-down indoor units in the calculation, not only is the frequency adjustment more accurately reflected in the actual load demand, but transient disturbances are also effectively avoided. In summary, this application significantly improves the accuracy and adaptability of frequency regulation, enhances the system's operational stability and anti-interference capability during room number switching, and provides a more reliable and robust control foundation for subsequent coordinated opening control of indoor and outdoor electronic expansion valves based on frequency change ratios.

[0011] In some embodiments, the first rule is:

[0012] in, This is a pressure change correction factor. This is the correction factor for temperature changes.

[0013] In the above embodiments, this application further introduces preset pressure change correction coefficients and temperature change correction coefficients. These coefficients incorporate the potential operational risks caused by changes in exhaust pressure or intake temperature during room number switching in the multi-split air conditioning system into the calculation of frequency change through empirical compensation, making the calculation of frequency change more accurate. Furthermore, this application further enhances the stability and operational safety of the system during room number switching.

[0014] In some embodiments, the controller is configured to: In adjustment mode, read the compressor operating frequency when the number of the indoor units that are turned on changes, and determine it as the historical operating frequency; Determine whether the number of indoor units increases after the change occurs; If so, then set the frequency change to a positive value; If not, then set the frequency change to a negative value; The target operating frequency is obtained by adding the historical operating frequency to the frequency change. The compressor is controlled to operate at the target operating frequency.

[0015] In the above embodiments, when the number of indoor units in operation changes, this application first reads the historical operating frequency of the compressor, then determines whether the number of indoor units has increased or decreased after the change, and sets the positive or negative sign of the frequency change accordingly, so that the compressor frequency is adjusted in a direction that conforms to the system load change trend. On this basis, the historical operating frequency is added to the frequency change to obtain the target operating frequency, which not only ensures the rationality and safety of frequency transition, but also significantly improves the stability of system operation during the switching of the number of indoor units.

[0016] In some embodiments, the controller is configured to: calculate the ratio of the target operating frequency to the historical operating frequency, and determine the ratio as the frequency change ratio.

[0017] In the above embodiments, this application calculates the frequency change ratio by comparing the target operating frequency with the historical operating frequency, thereby converting the compressor frequency adjustment into a dimensionless relative change factor. This ratio accurately reflects the relative change in system load before and after room number switching, avoiding the flow distribution mismatch problem that may result from relying solely on the absolute frequency change.

[0018] In some embodiments, the second rule is: Obtain the historical opening degree of the indoor electronic expansion valve corresponding to each of the indoor units that have been turned on; Based on the frequency change ratio, calculate the total opening change of the indoor electronic expansion valves corresponding to all the activated indoor units. Based on the ratio between the rated capacities of each of the indoor units that have been turned on, the change in the total opening degree is allocated to the indoor electronic expansion valves corresponding to each of the indoor units that have been turned on, thereby obtaining the single valve opening adjustment amount of each indoor electronic expansion valve. The target opening degree of each single valve is obtained by adding the adjustment amount of each valve to the historical opening degree of the indoor electronic expansion valve corresponding to each opened indoor unit.

[0019] In the above embodiments, this application calculates the total opening change of the indoor electronic expansion valves based on the frequency change ratio, and distributes this opening change to each indoor unit based on the ratio between the rated capacities of the indoor units. Subsequently, the target opening of the indoor electronic expansion valve corresponding to each opened indoor unit is obtained sequentially, thereby achieving coordinated and orderly adjustment of the indoor electronic expansion valves of multiple indoor units. Since the frequency change ratio reflects the relative change in compressor load, using this as the basis for opening adjustment ensures that the refrigerant flow distribution can maintain dynamic matching with the overall system operating state, avoiding problems such as poor oil return, abnormal suction superheat, or localized overcooling caused by sudden valve opening changes or distribution imbalances.

[0020] In some embodiments, the formula for calculating the change in opening degree is:

[0021] Wherein, ΔEI(n) is the change in the total opening degree of the indoor electronic expansion valve; The sum of the opening degrees of the indoor electronic expansion valves corresponding to all the indoor units that are already in operation, before the number of indoor units that are already in operation changes. The frequency change ratio; H represents the theoretical sum of the opening degrees of the indoor electronic expansion valves corresponding to all the indoor units that have been turned on, after the number of indoor units that have been turned on has changed; H is the indoor unit capacity coefficient.

[0022] In the above embodiments, this application replaces the existing technology's static allocation of indoor electronic expansion valves based on a dynamic calculation method that uses the sum of the opening degrees of the indoor electronic expansion valves before and after room number switching as a ratio to the frequency change. This method can dynamically amplify the opening adjustment of the indoor electronic expansion valves after room number switching according to the actual changing trend of the system load, thereby enhancing the strength and adaptability of the throttling response. Especially under typical transient conditions such as a reduction in the number of indoor units or the start-up and shutdown of large-capacity units, this application achieves a more sensitive and accurate flow redistribution strategy, significantly improving the operational stability and coordination of the multi-split air conditioning system during room number switching.

[0023] In some embodiments, the third rule is: Read the opening degree of the outdoor electronic expansion valve when the number of the indoor units that have been turned on changes, and determine it as the historical opening degree; Based on the frequency change ratio, calculate the opening change of the outdoor electronic expansion valve; The target opening degree of the outdoor electronic expansion valve is obtained by adding its historical opening degree to its opening degree change.

[0024] In the above embodiments, this application reads the opening degree of the outdoor electronic expansion valve as a historical opening degree when the number of indoor units changes, and calculates its target opening degree by combining it with the frequency change ratio, so that the adjustment of the outdoor electronic expansion valve is synchronized with the relative change of the compressor frequency. This mechanism ensures that the throttling capacity on the outdoor side can dynamically match the overall system load level, avoiding pressure fluctuations or refrigerant circulation imbalances caused by the disconnect between the compressor operating frequency adjustment and the opening degree of the outdoor electronic expansion valve. Therefore, it not only significantly improves the timeliness and coordination of the outdoor electronic expansion valve response, but also provides key support for the stable and efficient operation of multi-split systems under transient conditions such as room number switching.

[0025] In some embodiments, the formula for calculating the change in opening of the outdoor electronic expansion valve is:

[0026] in, The change in the opening degree of the outdoor electronic expansion valve; The historical opening degree of the outdoor electronic expansion valve before the number of the indoor units that have been turned on changes; The frequency change ratio; This is the opening compensation amount of the outdoor electronic expansion valve.

[0027] In the above embodiments, this application, based on the dynamic adjustment of the outdoor electronic expansion valve opening according to the frequency change ratio, further introduces an opening compensation amount for the outdoor electronic expansion valve. This compensation amount is a fixed empirical value pre-calibrated according to typical system operating conditions, used to offset flow deviations caused by differences in piping configuration, refrigerant charge, or environmental conditions, thereby making the calculation of the opening change more accurate. Compared to the adjustment method that relies solely on proportional scaling, this application, while maintaining the ability to respond quickly to load changes, significantly enhances the operational safety and robustness of the system under extreme conditions, providing more reliable flow assurance for multi-split air conditioning systems during transient processes such as room number switching.

[0028] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the overall structure of the multi-split air conditioning system provided in the embodiments of this application; Figure 2 This is a schematic diagram of the outdoor unit provided in an embodiment of this application; Figure 3 This is a schematic diagram of the indoor structure of the multi-split air conditioning system provided in the embodiments of this application; Figure 4 This is a schematic diagram of the structure of the indoor unit provided in the embodiment of this application; Figure 5 This is a control flowchart of the multi-split air conditioning system provided in the embodiments of this application; Figure 6This is a flowchart of the method for determining the positive or negative value of frequency change provided in the embodiments of this application; Figure 7 This is a flowchart illustrating the adjustment of the compressor operating frequency provided in an embodiment of this application; Figure 8 This is a flowchart illustrating the calculation of the frequency change ratio provided in an embodiment of this application; Figure 9 This is a control flowchart of the second rule provided in the embodiments of this application; Figure 10 This is a control flowchart of the third rule provided in the embodiments of this application.

[0031] In the above diagrams: 100, outdoor unit; 110, compressor; 120, gas-liquid separator; 130, outdoor electronic expansion valve; 140, outdoor heat exchanger; 150, four-way valve; 160, outdoor circuit; 200, indoor unit; 210, indoor heat exchanger; 220, indoor electronic expansion valve; 230, shut-off valve; 240, indoor circuit. Detailed Implementation

[0032] In this application, the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", etc., indicating directions or positional relationships, are based on the accompanying drawings and are used only for ease of description, and do not constitute a limitation on the specific structure or operation of the device or component.

[0033] Furthermore, unless otherwise explicitly stated, terms such as “installation,” “connection,” and “fixation” should be interpreted broadly to include various connection or fixing methods, whether direct or indirect, mechanical or electrical, detachable or integrated, and their specific meanings can be reasonably determined by those skilled in the art in light of the context.

[0034] Secondly, the first feature being "above" or "below" the second feature can mean that the two are in direct contact or can be indirect contact through an intermediate medium; among them, "above", "above", and "on top" indicate that the first feature is located directly above, diagonally above, or only higher in height than the second feature, and the same applies to "below", "below", and "below".

[0035] Furthermore, the terms "one embodiment" and "some embodiments" mean that the features, structures, or characteristics are included in at least one embodiment or example of this application; the technical features of different embodiments or examples can be arbitrarily combined without contradicting each other.

[0036] Finally, the meaning of "and / or" in the text covers three parallel situations. Taking "A and / or B" as an example, these include: only A, only B, or A and B exist simultaneously.

[0037] The present application will be specifically described below through exemplary embodiments; it should be understood that, unless otherwise specified, elements, structures or features in one embodiment may be advantageously applied to other embodiments without conflict.

[0038] A multi-split air conditioning system typically consists of one outdoor unit and multiple indoor units. The outdoor unit includes a compressor, an outdoor heat exchanger, and an outdoor electronic expansion valve, while the indoor units are equipped with indoor heat exchangers and indoor electronic expansion valves. This system achieves independent regulation of refrigerant flow in each indoor unit by adjusting the compressor speed and dynamically controlling the opening of each indoor electronic expansion valve, thus flexibly meeting the dynamic load demands of different rooms. Due to this advantage, multi-split systems are widely used in commercial office buildings, hotels, and high-end residences.

[0039] However, during the switching of indoor units, existing multi-split air conditioning systems typically focus only on adjusting the indoor electronic expansion valve, failing to achieve coordinated operation between the indoor valve, outdoor valve, and compressor. This limitation means that existing multi-split air conditioning systems can only achieve precise control of the indoor electronic expansion valve when dealing with a single model of indoor unit, thus avoiding sudden changes in refrigerant flow and ensuring stable system operation, but lack universal adaptability to combinations of various indoor unit models. In practical applications, however, the same outdoor unit often needs to connect to multiple indoor units of different types, capacities, or specifications, which significantly complicates the system's load distribution and pressure response characteristics.

[0040] In this scenario, when the user changes the number of operating indoor units (e.g., increasing from three to four, or decreasing from five to two), the lack of global coordination within the existing system often leads to a sudden change in the total opening degree of the indoor electronic expansion valves. This causes abrupt changes in refrigerant flow, further resulting in drastic fluctuations in compressor load and an abnormally high compressor discharge temperature. Excessively high discharge temperatures can trigger the system's high-temperature protection mechanism, leading to unplanned shutdowns and impacting the user experience. Furthermore, it can accelerate the aging of the compressor lubricating oil, reducing the long-term reliability of the equipment.

[0041] Based on this, this application provides a multi-split air conditioning system, the purpose of which is to effectively solve the problem of excessively high exhaust temperature of compressor 110 of outdoor unit 100 caused by the sudden change in the total opening of indoor electronic expansion valves 220 during the switching of indoor units 200 in the existing system, by adjusting the opening degree of each indoor electronic expansion valve 220 and coordinating the opening degree of outdoor electronic expansion valve 130 and the operating frequency of compressor 110, so as to ensure the stability and reliability of system operation.

[0042] In the following, embodiments of this application will be described in detail with reference to the accompanying drawings.

[0043] As attached Figures 1 to 10 As shown in an illustrative embodiment of this application, the multi-split air conditioning system includes an outdoor unit 100.

[0044] In some embodiments, the outdoor unit 100 includes a compressor 110. The compressor 110 is a gas pressurization device used to compress refrigerant from a low-pressure, low-temperature state to a high-pressure, high-temperature state. The compressor 110 compresses the incoming low-pressure gaseous refrigerant by mechanically moving internal moving parts (such as pistons, rotors, scroll plates, etc.) through a motor, converting it into a high-pressure gaseous refrigerant. The specific process mainly includes three typical stages: suction, compression, and discharge.

[0045] It is worth noting that the refrigerants mentioned in this application (such as R32, R410A, etc.) are heat transfer media, which are the same throughout the text and will not be repeated here.

[0046] In some embodiments, the outdoor unit 100 includes an outdoor electronic expansion valve 130; the outdoor electronic expansion valve 130 is a throttling element driven by a controller, which is installed on the liquid pipe at the outlet of the condenser to regulate the flow rate of high-pressure liquid refrigerant in order to match the operating frequency of the compressor 110 and the opening degree of the indoor electronic expansion valve 220, thereby achieving dynamic matching of the system refrigerant flow rate and improving operating efficiency and stability.

[0047] In some embodiments, the outdoor unit 100 includes a gas-liquid separator 120; the gas-liquid separator 120 is disposed at the front end of the suction port of the compressor 110, and is used to separate the liquid components entrained in the refrigerant flowing back to the compressor 110, to prevent the liquid refrigerant from entering the compression chamber and causing liquid slugging, and to ensure the safe and reliable operation of the compressor 110.

[0048] In some embodiments, the outdoor unit 100 includes an outdoor heat exchanger 140; the outdoor heat exchanger 140 is an air-cooled heat exchanger, typically composed of finned tubes, which acts as a condenser in cooling mode to condense high-pressure gaseous refrigerant into high-pressure liquid refrigerant, and in heating mode to act as an evaporator to absorb ambient heat and cause the refrigerant to evaporate.

[0049] In some embodiments, the outdoor unit 100 includes a four-way valve 150; the four-way valve 150 is used to switch the flow direction of the refrigerant to realize the conversion between cooling mode and heating mode; specifically, it guides the high-pressure refrigerant to flow to the outdoor heat exchanger 140 during cooling and guides it to flow to the indoor unit 200 during heating, and is the core component of the multi-split air conditioning system to realize the switching between cooling and heating.

[0050] In some embodiments, the multi-split air conditioning system includes at least two indoor units 200, each indoor unit 200 being connected to an outdoor unit 100 via refrigerant piping, forming a multi-branch refrigerant circulation loop centered on the outdoor unit 100.

[0051] In some embodiments, the indoor unit 200 includes an indoor heat exchanger 210; the indoor heat exchanger 210 is a finned tube heat exchanger used for heat exchange with indoor air, absorbing indoor heat as an evaporator in cooling mode, and releasing heat to the room as a condenser in heating mode.

[0052] In some embodiments, the indoor unit 200 includes an indoor electronic expansion valve 220; the indoor electronic expansion valve 220 is disposed on the refrigerant inlet side of the indoor heat exchanger 210 and is driven by a controller to regulate the refrigerant flow into the indoor heat exchanger 210 in order to match the operating frequency of the compressor 110 and the opening degree of the outdoor electronic expansion valve 130, thereby achieving dynamic matching of the system refrigerant flow and improving operating efficiency and stability.

[0053] In some embodiments, the indoor unit 200 includes two shut-off valves 230; the two shut-off valves 230 are respectively disposed on the refrigerant inlet pipe and outlet pipe connecting the indoor unit 200 and the outdoor unit 100, and are used to cut off the refrigerant passage during installation, maintenance or shutdown, so as to facilitate system maintenance and sealing.

[0054] In some embodiments, the multi-split air conditioning system includes a controller. The controller is used to coordinate and control the outdoor unit 100 and each indoor unit 200 according to the user's operating settings (such as set temperature, operating mode, on / off commands, etc.) and the programs and configuration parameters preset at the system's factory. The controller can be a main control unit located inside the outdoor unit 100 or an independent centralized control device. It integrates a processor, memory, and communication module and is capable of executing the frequency regulation, electronic expansion valve opening calculation, and coordinated control logic of this application.

[0055] In some embodiments, the controller is configured to: The controller determines whether the number of currently active indoor units (200) has changed. Specifically, the controller obtains the current operating status of each indoor unit and compares it with the operating status of the previous time to determine whether the number of active indoor units has changed.

[0056] If so, then enter adjustment mode; If not, wait for a preset time and then re-evaluate whether the number of currently active indoor units has changed. The preset time is used to avoid the controller from frequently performing detection operations and wasting system resources. Its value can be 0.5 seconds, 1 second, or other suitable time intervals. Entering adjustment mode, calculate the total rated capacity of all currently active indoor units 200; The frequency variation of compressor 110 is obtained based on the sum of rated capacities using the first rule. Adjust the operating frequency of compressor 110 according to the frequency change; Calculate the frequency change ratio based on the frequency change amount; Based on the frequency change ratio, the target opening degree of the indoor electronic expansion valve 220 corresponding to each opened indoor unit 200 is obtained through the second rule, and the target opening degree of the outdoor electronic expansion valve 130 is obtained through the third rule. Control the indoor electronic expansion valve 220 corresponding to each of the already turned-on indoor units 200 to adjust to their respective target opening degree, and control the outdoor electronic expansion valve 130 to adjust to its target opening degree.

[0057] Rated capacity refers to the cooling or heating capacity of indoor unit 200 under standard operating conditions, measured in horsepower (HP), and is used to characterize the load demand of a single indoor unit 200. The operating frequency of compressor 110 refers to the power supply frequency driving the motor of compressor 110, measured in Hz, and its value directly determines the speed of compressor 110 and the amount of refrigerant circulating. The opening degree of electronic expansion valve refers to the degree to which the valve needle is open relative to the fully closed position, and is used to control the refrigerant flow rate. Its value is achieved by the controller driving the stepper motor with pulse signals, and the unit of opening degree is pls (pulses). The larger the opening degree, the larger the refrigerant flow cross-sectional area and the higher the flow rate.

[0058] In some embodiments, the multi-split air conditioning system includes an outdoor circuit 160; the outdoor circuit 160 refers to the main refrigerant circulation path consisting of a compressor 110, an outdoor heat exchanger 140, a four-way valve 150, a gas-liquid separator 120 and connecting pipes, which is used to complete key circulation functions such as refrigerant compression, condensation (or evaporation) and delivery to the indoor side.

[0059] The compressor 110 is used to compress the low-pressure, low-temperature gaseous refrigerant into a high-pressure, high-temperature gaseous refrigerant and provide circulating power for the entire system.

[0060] In some embodiments, the multi-split air conditioning system includes an outdoor electronic expansion valve 130, which is disposed on the outdoor circuit 160. The outdoor electronic expansion valve 130 is used to control the opening of the outdoor circuit 160 to regulate the refrigerant flow through the outdoor circuit 160.

[0061] In some embodiments, the multi-split air conditioning system includes several indoor circuits 240, each indoor circuit 240 corresponding to an indoor unit 200; the indoor circuits 240 are arranged in parallel and connected to the outdoor circuits 160 respectively, forming a multi-branch refrigerant distribution structure, so that each indoor unit 200 can independently perform heat exchange and flow control.

[0062] In some embodiments, an indoor heat exchanger 210 is provided on the indoor circuit 240; the indoor heat exchanger 210 is used to exchange heat with indoor air, absorb indoor heat in cooling mode to cause refrigerant to evaporate, and release heat in heating mode to cause refrigerant to condense, thereby achieving temperature regulation of the indoor environment.

[0063] In some embodiments, the multi-split air conditioning system includes a plurality of indoor electronic expansion valves 220, which are disposed on the indoor circuit 240. The indoor electronic expansion valves 220 are used to control the opening degree of the indoor circuit 240 to independently control the refrigerant flow of the indoor circuit 240, thereby adjusting the heat exchange capacity of each indoor unit 200 and realizing on-demand cooling or heating.

[0064] In some embodiments, the multi-split air conditioning system includes a controller, which is configured to: Determine if the number of currently active indoor circuits (240) has changed; If so, then enter adjustment mode; If not, wait for the preset time and then re-evaluate whether the number of currently activated indoor circuits 240 has changed; Entering the adjustment mode, calculate the total rated capacity of all currently activated indoor circuits 240; where the rated capacity of indoor circuit 240 is the rated capacity of the indoor unit 200 corresponding to indoor circuit 240. The frequency variation of compressor 110 is obtained based on the sum of rated capacities using the first rule. Adjust the operating frequency of compressor 110 according to the frequency change; The frequency change ratio is calculated based on the frequency change amount; Based on the frequency change ratio, the target opening degree of the indoor electronic expansion valve 220 corresponding to each opened indoor unit 200 is obtained through the second rule, and the target opening degree of the outdoor electronic expansion valve 130 is obtained through the third rule. Control the indoor electronic expansion valve 220 corresponding to each of the already turned-on indoor units 200 to adjust to their respective target opening degree, and control the outdoor electronic expansion valve 130 to adjust to its target opening degree.

[0065] In the above embodiments, this application calculates the frequency change of compressor 110 based on the total rated capacity of the activated indoor units 200 when the number of activated indoor units 200 changes, and further calculates the frequency change ratio of compressor 110. This allows for the synchronous adjustment of the operating frequency of compressor 110, the opening degree of outdoor electronic expansion valve 130, and the opening degree of indoor electronic expansion valve 220 corresponding to each activated indoor unit 200. This constructs a linkage mechanism that precisely allocates the opening degree of indoor electronic expansion valve 220 and coordinates the operating frequency of compressor 110 and the opening degree of outdoor electronic expansion valve 130. This linkage mechanism effectively avoids the refrigerant flow mutation problem caused by a sudden change in the total opening degree of indoor electronic expansion valve 220 in the prior art, enabling the system refrigerant flow to dynamically match with load changes. It significantly suppresses drastic fluctuations in exhaust pressure and temperature during room number switching, specifically addressing the industry pain point of excessively high compressor 110 exhaust temperature in multi-split air conditioning systems under room number switching conditions. Meanwhile, since this application uses the frequency change ratio as a unified correlation parameter to drive the opening adjustment of the indoor and outdoor electronic expansion valves, it does not rely on a specific model or capacity combination of indoor unit 200. This breaks through the limitation that traditional control logic is only applicable to the same type of unit, and significantly improves the system's compatibility and adaptability to different types of indoor units 200 and its operational reliability under complex dynamic conditions.

[0066] In some embodiments, the first rule is:

[0067] in, The variable is the frequency change of the compressor, and N is a correction factor. This represents the total rated capacity of all currently active indoor units. This is a correction factor for frequency variation. This is the correction factor for the indoor unit when it is turned off.

[0068] Among them, the correction factor N serves as the global gain factor, which adjusts the overall frequency change proportionally; the frequency change correction factor... Its function is to adjust the sum of the rated capacities of all active indoor units 200; the correction factor for the shut-down indoor unit 200. This is used to compensate for the inherent deviation caused by the indoor unit 200 that has been turned off during the switching of room numbers, thereby improving the accuracy and stability of frequency adjustment.

[0069] Specifically, the correction factor N and the frequency change correction factor Correction factor of 200 for indoor units that are turned off The correction factor is related to the model and specifications of the outdoor unit 100, as well as the number, model, and specifications of the connected indoor units 200. Since different configurations of multi-split air conditioning systems differ in refrigerant circulation characteristics, load response characteristics, and pipe resistance, the aforementioned correction factor needs to be determined through experimental calibration based on the specific unit combination. In practical engineering applications, technicians typically conduct on-site testing and parameter tuning based on typical operating conditions during the system installation or commissioning phase to ensure the accuracy and adaptability of the control strategy.

[0070] In some embodiments, the correction factor N is 1.2.

[0071] In some embodiments, frequency change correction factor It is 0.9.

[0072] In some embodiments, the indoor unit is turned off with a correction factor of 200. It is 2.9.

[0073] In the above embodiments, this application establishes a direct correlation between the frequency change of compressor 110 and the total rated capacity of all currently active indoor units 200, constructing a dynamic control mechanism that matches the current actual operating conditions of the system. Simultaneously, by introducing correction coefficients N, Kc(k), and Kcd(k) for the shut-down indoor units 200 in the calculation, not only is the frequency adjustment more accurately reflected in the actual load demand, but transient disturbances are also effectively avoided. In summary, this application significantly improves the accuracy and adaptability of frequency regulation, enhances the system's operational stability and anti-interference capability during room number switching, and provides a more reliable and robust control foundation for subsequent coordinated opening control of indoor and outdoor electronic expansion valves based on frequency change ratios.

[0074] In some embodiments, the first rule is:

[0075] in, This is a pressure change correction factor. This is the correction factor for temperature changes.

[0076] Among them, the pressure change correction coefficient This is used to introduce empirical compensation related to the dynamic characteristics of system pressure in the calculation of frequency changes, to accommodate typical pressure response deviations under different pipe lengths or installation configurations; temperature change correction factor. It is used to empirically compensate for the differences in heating or cooling that may occur in the compressor 110 at different operating frequencies when calculating the frequency change.

[0077] Specifically, pressure change correction factor and temperature change correction factor The correction factor is related to the model and specifications of the outdoor unit 100, as well as the number, model, and specifications of the connected indoor units 200. Since different configurations of multi-split air conditioning systems differ in refrigerant circulation characteristics, load response characteristics, and pipe resistance, the aforementioned correction factor needs to be determined through experimental calibration based on the specific unit combination. In practical engineering applications, technicians typically conduct on-site testing and parameter tuning based on typical operating conditions during the system installation or commissioning phase to ensure the accuracy and adaptability of the control strategy.

[0078] In some embodiments, pressure change correction factor It is 0.8.

[0079] In some embodiments, temperature change correction factor It is 0.5.

[0080] In the above embodiments, this application further introduces preset pressure change correction coefficients and temperature change correction coefficients. These coefficients incorporate the potential operational risks caused by changes in exhaust pressure or intake temperature during room number switching in the multi-split air conditioning system into the calculation of frequency change through empirical compensation, making the calculation of frequency change more accurate. Furthermore, this application further enhances the stability and operational safety of the system during room number switching.

[0081] In some embodiments, the controller is configured to: In adjustment mode, read the compressor 110's operating frequency when the number of activated indoor units 200 changes, and determine it as the historical operating frequency. Specifically, the controller will monitor and record the current operating frequency of the compressor 110 in real time. When it detects a change in the number of indoor units 200 that have been turned on, it will determine the operating frequency value of the compressor 110 at the time of the change as the historical operating frequency for use in the calculation of the subsequent target frequency.

[0082] Determine whether the number of indoor units 200 increases after the change occurs; If so, set the frequency change to a positive value; If not, then set the frequency change to a negative value; Add the historical operating frequency to the frequency change to obtain the target operating frequency. ; Control the compressor 110 to operate at the target operating frequency.

[0083] In the above embodiments, when the number of indoor units 200 in operation changes, this application first reads the historical operating frequency of the compressor 110, then determines whether the number of indoor units 200 has increased or decreased after the change, and sets the positive or negative sign of the frequency change accordingly, so that the frequency of the compressor 110 is adjusted in a direction that conforms to the trend of system load change. On this basis, the historical operating frequency is added to the frequency change to obtain the target operating frequency, which not only ensures the rationality and safety of frequency transition, but also significantly improves the stability of system operation during the switching of the number of indoor units.

[0084] In some embodiments, the controller is configured to calculate the ratio of the target operating frequency to the historical operating frequency and determine the ratio as the frequency change percentage.

[0085] In the above embodiments, this application calculates the frequency change ratio by comparing the target operating frequency with the historical operating frequency, thereby converting the frequency adjustment of compressor 110 into a dimensionless relative change factor. This ratio accurately reflects the relative change in system load before and after room number switching, avoiding the flow distribution mismatch problem that may be caused by relying solely on the absolute frequency change.

[0086] In some embodiments, the second rule is: The controller acquires the historical opening degree of the indoor electronic expansion valve 220 corresponding to each activated indoor unit 200. Specifically, the controller monitors and records the current opening degree of the indoor electronic expansion valve 220 corresponding to each activated indoor unit 200 in real time. When the number of activated indoor units 200 changes, the controller determines the opening degree of the indoor electronic expansion valve 220 corresponding to each activated indoor unit 200 at the time of the change as its historical opening degree. If the number of indoor units 200 increases, the controller determines the initial theoretical opening degree of the indoor electronic expansion valve 220 corresponding to the newly added indoor unit 200 as its corresponding historical opening degree. Based on the frequency change ratio, calculate the total opening change of the indoor electronic expansion valve 220 corresponding to all the turned-on indoor units 200. Based on the ratio between the rated capacities of each of the activated indoor units 200, the total change in opening degree is allocated to the corresponding indoor electronic expansion valves 220 of each activated indoor unit 200, thus obtaining the single valve opening adjustment amount of each indoor electronic expansion valve 220. For example, if there are three activated indoor units 200, the ratio between their rated capacities is 1:1:2, and the total change in opening degree is 100, then the single valve opening adjustment amounts of the three indoor electronic expansion valves 220 are 25, 25, and 50, respectively. The opening adjustment of each single valve is added to the historical opening of the indoor electronic expansion valve 220 corresponding to each opened indoor unit 200 to obtain the target opening of each indoor electronic expansion valve 220.

[0087] The initial theoretical opening degree of the indoor electronic expansion valve 220 when the indoor unit 200 is turned on is determined by the controller from the opening degree-load mapping relationship pre-stored in the controller's memory, based on the rated capacity of the indoor unit 200, the user-set target temperature, and the operating mode (cooling or heating). This mapping relationship (usually in the form of calibration tables or empirical formulas) is determined by air conditioning manufacturers during the product development phase through extensive bench testing, verifying the correspondence between different load demands and the electronic expansion valve opening required for stable operation under standard operating conditions.

[0088] In the above embodiments, this application calculates the total opening change of the indoor electronic expansion valves 220 based on the frequency change ratio, and distributes this opening change to each indoor unit 200 based on the ratio between the rated capacities of the indoor units 200. Subsequently, the target opening of the indoor electronic expansion valves 220 corresponding to each opened indoor unit 200 is obtained sequentially, thereby achieving coordinated and orderly adjustment of the indoor electronic expansion valves 220 of multiple indoor units 200. Since the frequency change ratio reflects the relative change in the load of the compressor 110, using this as the basis for opening adjustment ensures that the refrigerant flow distribution can dynamically match the overall system operating state, avoiding problems such as poor oil return, abnormal suction superheat, or localized overcooling caused by sudden valve opening changes or distribution imbalances.

[0089] In some embodiments, the formula for calculating the change in opening degree is:

[0090] Wherein, ΔEI(n) is the total opening change of the indoor electronic expansion valve 220, in units of pls; The total opening degree of the indoor electronic expansion valve 220 corresponding to all the indoor units 200 that have been turned on before the number of indoor units 200 changes, in pls. This represents the percentage change in frequency. The sum of the theoretical opening degrees of the indoor electronic expansion valves 220 corresponding to all the indoor units 200 that have been turned on when the number of indoor units 200 changes, in units of pls; H is the indoor unit capacity coefficient.

[0091] Furthermore, the indoor unit capacity factor H is related to the model and specifications of the outdoor unit 100, as well as the number, model, and specifications of the connected indoor units 200. Since different configurations of multi-split air conditioning systems differ in refrigerant circulation characteristics, load response characteristics, and pipe resistance, the aforementioned correction factor needs to be determined through experimental calibration based on the specific unit combination. In practical engineering applications, technicians typically conduct on-site testing and parameter tuning based on typical operating conditions during the system installation or commissioning phase to ensure the accuracy and adaptability of the control strategy.

[0092] In some embodiments, the indoor unit capacity factor H is 1.

[0093] Furthermore, the theoretical total opening refers to the total opening of the electronic expansion valves determined by the system based on the current status of the active indoor units 200 when the number of indoor units 200 changes. Specifically, when the number of active indoor units 200 decreases, the theoretical total opening is the sum of the actual openings of the electronic expansion valves corresponding to the remaining active indoor units 200 before any adjustments are made. For example, if the number of indoor units 200 decreases from 4 to 3, the theoretical total opening is equal to the sum of the current electronic expansion valve openings of the 3 active indoor units 200. When the number of already activated indoor units 200 increases, the total theoretical opening degree consists of two parts: one part is the sum of the current unadjusted opening degrees of the electronic expansion valves corresponding to the already activated indoor units 200, and the other part is the initial theoretical opening degree of the newly activated indoor unit 200 according to user settings (such as target temperature, operating mode, etc.). For example, if the number of indoor units 200 increases from 3 to 4, the total theoretical opening degree is equal to the sum of the current electronic expansion valve opening degrees of the original 3 indoor units 200, plus the initial theoretical opening degree of the newly activated 4th indoor unit 200 determined according to its operating requirements.

[0094] It should be noted that the controller will monitor and record the current opening degree of the indoor electronic expansion valve 220 corresponding to each indoor unit 200 in real time for system use.

[0095] In the above embodiments, this application replaces the existing method of statically allocating each indoor electronic expansion valve 220 based on a fixed coefficient by employing a dynamic calculation method based on the ratio of the sum of the opening degrees of the indoor electronic expansion valves 220 before and after the number of rooms is switched to the frequency change. This method can dynamically amplify the opening adjustment of the indoor electronic expansion valves 220 after the number of rooms is switched according to the actual change trend of the system load, thereby enhancing the strength and adaptability of the throttling response. Especially under typical transient conditions such as a reduction in the number of indoor units 200 or the start-up and shutdown of large-capacity units, this application achieves a more sensitive and accurate flow redistribution strategy, significantly improving the operational stability and coordination of the multi-split air conditioning system during the number of rooms switching process.

[0096] In some embodiments, the third rule is Read the opening degree of the outdoor electronic expansion valve 130 when the number of indoor units 200 that have been turned on changes, and determine it as the historical opening degree; Based on the frequency change ratio, calculate the opening change of the outdoor electronic expansion valve 130. The target opening of the outdoor electronic expansion valve 130 is obtained by adding its historical opening degree to its opening degree change.

[0097] It should be noted that the controller will monitor and record the current opening degree of the outdoor electronic expansion valve 130 in real time for system use.

[0098] In the above embodiments, this application reads the opening degree of the outdoor electronic expansion valve 130 as a historical opening degree when the number of indoor units 200 changes, and calculates its target opening degree by combining it with the frequency change ratio, so that the adjustment of the outdoor electronic expansion valve 130 keeps synchronized with the relative change of the compressor 110 frequency. This mechanism ensures that the outdoor side throttling capacity can dynamically match the overall system load level, avoiding pressure fluctuations or refrigerant circulation imbalances caused by the disconnect between the compressor 110 operating frequency adjustment and the opening degree of the outdoor electronic expansion valve 130. Therefore, it not only significantly improves the timeliness and coordination of the response of the outdoor electronic expansion valve 130, but also provides key support for the stable and efficient operation of multi-split systems under transient conditions such as room number switching.

[0099] In some embodiments, the formula for calculating the change in opening of the outdoor electronic expansion valve 130 is as follows:

[0100] in, The change in opening of the outdoor electronic expansion valve 130 is expressed in pls. The historical opening degree of the outdoor electronic expansion valve 130 before the number of indoor units 200 that have been turned on changes, in pls; This represents the percentage change in frequency. This is the opening compensation amount for the outdoor electronic expansion valve 130, measured in pls.

[0101] In some embodiments, the opening compensation amount of the outdoor electronic expansion valve 130 It is 60pls.

[0102] In the above embodiments, based on the dynamic calculation of the opening change of the outdoor electronic expansion valve 130 according to the frequency change ratio, this application further introduces an opening compensation amount for the outdoor electronic expansion valve 130. This compensation amount is a fixed empirical value pre-calibrated according to the typical operating conditions of the system, used to offset the flow deviation caused by differences in pipeline configuration, refrigerant charge, or environmental conditions, thereby making the calculation of the opening change more accurate. Compared with the adjustment method that only relies on proportional scaling, this application significantly enhances the operational safety and robustness of the system under extreme conditions while maintaining the ability to respond quickly to load changes, providing a more reliable flow guarantee for multi-split air conditioning systems during transient processes such as room number switching.

[0103] To illustrate the operating principle of this application, the following specific examples are provided. It should be noted that the numerical values ​​used in the following examples are merely illustrative of the technical solution of this application and do not constitute any limitation on the scope of protection of this application; those skilled in the art should understand that the relevant parameters in actual applications may differ from the examples below.

[0104] Assume there are five rooms, each equipped with one of five indoor units 200, named sequentially as Indoor Unit 1, Indoor Unit 2, Indoor Unit 3, Indoor Unit 4, and Indoor Unit 5. Each indoor unit 200 is equipped with an independent indoor electronic expansion valve 220, namely, Indoor Electronic Expansion Valve 1, Indoor Electronic Expansion Valve 220 ...

[0105] It is known that three indoor units 200 are currently turned on: the first indoor unit, the second indoor unit, and the third indoor unit. At this time, the opening degree of the electronic expansion valve of the first indoor unit is 1200 pls, the opening degree of the electronic expansion valve of the second indoor unit is 800 pls, and the opening degree of the electronic expansion valve of the third indoor unit is 1000 pls. Therefore, the total opening degree of the indoor electronic expansion valve 220 corresponding to the three turned-on indoor units 200 is 3000 pls. Furthermore, the historical opening degree of the outdoor electronic expansion valve 130 is also known. The operating frequency of compressor 110 is 100Hz, with a value of 1800 pls. This operating state serves as the initial condition before the room number switching and is used to calculate the subsequent frequency change ratio and the adjustment amount of the electronic expansion valve opening.

[0106] The user now activates a fourth indoor unit, increasing the number of active indoor units 200 from three to four. Based on the user's settings for the target temperature and operating mode of the fourth indoor unit, and considering its rated capacity, the controller determines the initial theoretical opening of the electronic expansion valve for the fourth indoor unit to be 1000 pls. At this point, the theoretical total opening of the electronic expansion valves 220 corresponding to the four active indoor units 200 is 4000 pls, far exceeding 3000 pls. Therefore, directly setting the opening of the fourth indoor electronic expansion valve to 1000 pls would inevitably cause a sudden change in the total opening of the electronic expansion valves 220 corresponding to the active indoor units 200, thus affecting the stable operation of the system. Therefore, this application necessitates a coordinated adjustment.

[0107] First, according to the formula Calculate the frequency change of compressor 110; where the total rated capacity of all currently active indoor units 200 is included. =1.5 + 2.0 + 2.5 + 2.0 = 8, further... That is, the frequency change of compressor 110 is 12.34 Hz; in addition, since the number of indoor units 200 that are turned on is increasing, the frequency change is positive.

[0108] Therefore, the target operating frequency is 112.34 Hz, and the compressor 110 is controlled to operate at the target operating frequency; at the same time, since the historical operating frequency of the compressor 110 is 100 Hz, the frequency change ratio is calculated. It is 1.1234.

[0109] Secondly, according to the formula Calculate the total opening change of each indoor electronic expansion valve 220; where, The total is 1200 + 800 + 1000 = 3000. The result is 1200 + 800 + 1000 + 1000 = 4000; further, we can obtain... That is, the change in opening degree of the total opening degree. It is -629.8.

[0110] Since the ratio of the rated capacity of each activated indoor unit 200 is 1.5 : 2 : 2.5 : 2, the total opening change is allocated based on this ratio. The single valve opening adjustment amounts allocated to the indoor electronic expansion valves 220 corresponding to each activated indoor unit 200 are 118.0875, 157.45, 196.8125 and 157.45, respectively. Then, the above values ​​are rounded to the nearest integer, and the single valve opening adjustment amounts of each indoor electronic expansion valve 220 are finally obtained as 118, 157, 197 and 157, respectively.

[0111] Then, based on the single-valve opening adjustment of each indoor electronic expansion valve 220, the opening of each indoor electronic expansion valve 220 is adjusted. The target opening of the first indoor electronic expansion valve is 1082 pls, the second indoor electronic expansion valve is 643 pls, the third indoor electronic expansion valve is 803 pls, and the fourth indoor electronic expansion valve is 843 pls. Finally, the total opening of the indoor electronic expansion valves 220 corresponding to the four activated indoor units 200 is 3371 pls. Compared to the original total opening of 3000 pls for the three activated indoor units 200, the change is small, resolving the problem of a sudden change in the total opening.

[0112] Finally, according to The change in opening of the outdoor electronic expansion valve 130 was calculated. ;in, For 1800pls, If it is 60pls, then the calculation yields... It is 2082.12; subsequently, the calculated value is... Rounding up to the nearest integer, the change in opening of the outdoor electronic expansion valve 130 is 2082. Adding the change in opening of the outdoor electronic expansion valve 130 to the historical opening of the outdoor electronic expansion valve 130, the target opening of the outdoor electronic expansion valve 130 is 3882pls.

[0113] It should be noted that both the indoor electronic expansion valve 220 and the outdoor electronic expansion valve 130 have upper and lower limits for their opening. The upper limit corresponds to the fully open state of the valve, and the lower limit corresponds to the minimum allowable opening. During adjustment, if the calculated target opening is greater than or equal to the upper limit, it is set to the upper limit; if the target opening is less than or equal to the lower limit, it is set to the lower limit. The lower limit differs depending on whether the air conditioning system is in cooling or heating mode and must be calibrated at the factory according to system characteristics and actual operating requirements. This application does not impose any restrictions on this.

[0114] Finally, the controller adjusts the opening degrees of the first indoor electronic expansion valve, the second indoor electronic expansion valve, the third indoor electronic expansion valve, the fourth indoor electronic expansion valve, and the outdoor electronic expansion valve 130 to their respective target opening degrees.

[0115] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A multi-split air conditioning system, characterized in that, include: The outdoor unit includes a compressor and an outdoor electronic expansion valve; At least two indoor units, each of which is connected to the outdoor unit via a refrigerant pipeline, and each of the indoor units is equipped with an indoor electronic expansion valve; The controller is configured to: Determine whether the number of currently activated indoor units has changed; If so, then enter adjustment mode; If not, wait for a preset time and then reassess whether the number of currently activated indoor units has changed. Entering the adjustment mode, calculate the total rated capacity of all currently activated indoor units; The frequency change of the compressor is obtained based on the sum of the rated capacities according to the first rule; The operating frequency of the compressor is adjusted according to the frequency change. Calculate the frequency change ratio based on the frequency change amount; Based on the frequency change ratio, the target opening degree of the indoor electronic expansion valve corresponding to each of the activated indoor units is obtained through the second rule, and the target opening degree of the outdoor electronic expansion valve is obtained through the third rule. Control the indoor electronic expansion valves corresponding to each of the already turned-on indoor units to adjust to their respective target opening degrees, and control the outdoor electronic expansion valves to adjust to their target opening degrees.

2. The multi-split air conditioning system according to claim 1, characterized in that, The first rule is: in, The frequency change of the compressor is N, where N is a correction factor. This represents the total rated capacity of all currently active indoor units. This is a correction factor for frequency variation. This is the correction factor for the indoor unit when it is turned off.

3. A multi-split air conditioning system according to claim 2, characterized in that, The first rule is: in, This is a pressure change correction factor. This is the correction factor for temperature changes.

4. A multi-split air conditioning system according to any one of claims 1 to 3, characterized in that, The controller is configured to: In adjustment mode, read the compressor operating frequency when the number of the indoor units that are turned on changes, and determine it as the historical operating frequency; Determine whether the number of indoor units increases after the change occurs; If so, then set the frequency change to a positive value; If not, then set the frequency change to a negative value; The target operating frequency is obtained by adding the historical operating frequency to the frequency change. The compressor is controlled to operate at the target operating frequency.

5. A multi-split air conditioning system according to claim 4, characterized in that, The controller is configured to: calculate the ratio of the target operating frequency to the historical operating frequency, and determine the ratio as the frequency change ratio.

6. A multi-split air conditioning system according to any one of claims 1 to 3, characterized in that, The second rule is: Obtain the historical opening degree of the indoor electronic expansion valve corresponding to each of the indoor units that have been turned on; Based on the frequency change ratio, calculate the total opening change of the indoor electronic expansion valves corresponding to all the activated indoor units. Based on the ratio between the rated capacities of each of the indoor units that have been turned on, the change in the total opening degree is allocated to the indoor electronic expansion valves corresponding to each of the indoor units that have been turned on, thereby obtaining the single valve opening adjustment amount of each indoor electronic expansion valve. The target opening degree of each single valve is obtained by adding the adjustment amount of each valve to the historical opening degree of the indoor electronic expansion valve corresponding to each opened indoor unit.

7. A multi-split air conditioning system according to claim 6, characterized in that, The formula for calculating the change in opening degree is: Wherein, ΔEI(n) is the change in the total opening degree of the indoor electronic expansion valve; The sum of the opening degrees of the indoor electronic expansion valves corresponding to all the indoor units that are already in operation, before the number of indoor units that are already in operation changes. The frequency change ratio; H represents the theoretical sum of the opening degrees of the indoor electronic expansion valves corresponding to all the indoor units that have been turned on, after the number of indoor units that have been turned on has changed; H is the indoor unit capacity coefficient.

8. A multi-split air conditioning system according to any one of claims 1 to 3, characterized in that, The third rule is: Read the opening degree of the outdoor electronic expansion valve when the number of the indoor units that have been turned on changes, and determine it as the historical opening degree; Based on the frequency change ratio, calculate the opening change of the outdoor electronic expansion valve; The target opening degree of the outdoor electronic expansion valve is obtained by adding its historical opening degree to its opening degree change.

9. A multi-split air conditioning system according to claim 8, characterized in that, The formula for calculating the change in opening of the outdoor electronic expansion valve is as follows: in, The change in the opening degree of the outdoor electronic expansion valve; The historical opening degree of the outdoor electronic expansion valve before the number of the indoor units that have been turned on changes; The frequency change ratio; This is the opening compensation amount of the outdoor electronic expansion valve.

10. A multi-split air conditioning system, characterized in that, include: Outdoor circuit; The compressor is installed on the outdoor circuit; An outdoor electronic expansion valve is installed on the outdoor circuit and is used to control the opening degree of the outdoor circuit. Several indoor circuits are arranged in parallel, and the indoor circuits are connected to the outdoor circuits. Several indoor electronic expansion valves are installed on the indoor circuit and are used to control the opening degree of the indoor circuit. The controller is configured to: Determine whether the number of currently activated indoor circuits has changed; If so, then enter adjustment mode; If not, wait for a preset time and then reassess whether the number of currently activated indoor circuits has changed. Entering the adjustment mode, calculate the total rated capacity of all currently activated indoor circuits; The frequency change of the compressor is obtained based on the sum of the rated capacities according to the first rule; The operating frequency of the compressor is adjusted according to the frequency change. Calculate the frequency change ratio based on the frequency change amount; Based on the frequency change ratio, the target opening degree of the indoor electronic expansion valve corresponding to each of the activated indoor units is obtained through the second rule, and the target opening degree of the outdoor electronic expansion valve is obtained through the third rule. Control the indoor electronic expansion valves corresponding to each of the already turned-on indoor units to adjust to their respective target opening degrees, and control the outdoor electronic expansion valves to adjust to their target opening degrees.

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