Air conditioning system

Abstract

The air conditioning system comprises a plurality of indoor units, each indoor unit comprises an indoor heat exchanger, a throttling element and a processing module, and in a refrigeration mode, the indoor units are configured to set target superheat degrees for the indoor units according to indoor loads; based on the superheat degree deviation between the target superheat degree and the real-time superheat degree, the opening degree of an indoor throttling element is adjusted, so that the real-time superheat degree of the indoor unit is equal to the target superheat degree; judging whether the target superheat degree meets a preset steady-state stagnation condition or not; if yes, the air supply and return temperature difference of the indoor unit is obtained; judging whether the air supply and return temperature difference deviates from a preset temperature difference target zone; if yes, the target superheat degree of the corresponding indoor unit is corrected in a one-way mode, and the corrected target superheat degree is generated; based on the corrected superheat degree deviation between the corrected target superheat degree and the real-time superheat degree, the opening degree of an indoor throttling element is adjusted, so that the real-time superheat degree of the corresponding indoor unit is equal to the corrected target superheat degree; after the air conditioning system enters the steady state, the air supply and return temperature of the indoor unit can be further balanced.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, and more particularly to an air conditioning system. Background Technology

[0002] Multi-split air conditioning systems are centralized air conditioning solutions that connect multiple indoor units to one or more outdoor units, enabling precise temperature control of multiple independent spaces. Widely used in commercial buildings such as office buildings, hotels, and hospitals, multi-split air conditioning systems offer advantages such as high efficiency, energy saving, and flexible layout. In multi-split air conditioning systems, indoor electronic expansion valves (EVI) are typically used to precisely control the refrigerant flow of the indoor units. This ensures uniform refrigerant flow distribution across multiple indoor units, maximizing the cooling or heating capacity of each unit. It also ensures consistent supply and return air temperature differences across the units, preventing some indoor units from experiencing excessively high or low supply air temperatures.

[0003] In actual use, the matching degree between the air volume and cooling / heating capacity of indoor units of different models or specifications varies. They may employ heat exchangers with different numbers of rows and flow path designs. Even if the model or specifications are the same, different connection schemes (including the installation location of the indoor unit, pipe length, elevation difference, etc.) and the height difference between the indoor and outdoor units can affect the flow and distribution of refrigerant, leading to uneven refrigerant distribution. Existing technology addresses this problem by correcting the target superheat based on the load. However, when all indoor units are under excessively high or low loads, the target superheat corrected based on the load will be adjusted and locked at the boundary value. At this point, the differences in indoor unit models, specifications, and connection schemes still exist, and the refrigerant distribution remains uneven. Even if all indoor units have the same control target, due to factors such as different pipe resistance, different refrigerant flow rates entering each indoor unit, different levels of heat exchanger blockage, different fan speed attenuation, and different instantaneous room disturbances, large differences in the supply air temperature of each indoor unit can still occur, resulting in poor comfort.

[0004] The information disclosed in this background section is only intended to enhance the understanding of the background technology of this application, and therefore may include prior art that is not known to those skilled in the art. Summary of the Invention

[0005] This application provides an air conditioning system with several embodiments, including multiple indoor units. Each indoor unit includes an indoor heat exchanger, which is fluidly connected to an indoor throttling element. In cooling mode, the air conditioning system's processing module is configured to: set a target superheat for the indoor unit based on the indoor load; adjust the opening of the corresponding indoor throttling element based on the superheat deviation between the target superheat and the real-time superheat, so that the real-time superheat of the indoor unit equals the target superheat; determine whether the target superheat meets a preset steady-state stagnation condition; when the preset steady-state stagnation condition is met, obtain the supply and return air temperature difference of the indoor unit; determine whether the supply and return air temperature difference deviates from a preset temperature difference target band; if so, unidirectionally correct the target superheat of the corresponding indoor unit to generate a corrected target superheat; and adjust the opening of the corresponding indoor throttling element based on the corrected superheat deviation between the corrected target superheat and the real-time superheat, so that the real-time superheat of the corresponding indoor unit equals the corrected target superheat.

[0006] The above technical solution has the following advantages or beneficial effects: The air conditioning system provided in this application, according to the actual operating conditions, no longer follows the principle of unified control based on superheat deviation in the main control process, but establishes a correction loop to monitor whether the supply air and return air temperature difference belongs to the preset temperature difference target zone; for indoor units where the supply air and return air temperature difference deviates from the preset temperature difference target zone, asymmetric adjustment compensation and secondary distribution are performed; from the perspective of physical characteristics, superheat is relatively lagging, while supply air and return air temperature difference is sensitive and direct; thus, without changing the overall operation of the air conditioning system, by judging the steady-state stagnation conditions and redistributing the refrigerant through secondary arbitration, the heat exchange capacity of each indoor heat exchanger reaches a true dynamic balance with the instantaneous load and its own state, maintaining the overall comfort of the air conditioning system.

[0007] In some embodiments of this application, the processing module is configured to perform the following steps to establish a preset temperature difference target band: sampling the return air temperature and supply air temperature of the indoor unit; calculating the supply and return air temperature difference between the return air temperature and supply air temperature of the indoor unit; when it is determined that the target superheat meets the steady-state stagnation condition, calculating the average value of the real-time supply and return air temperature difference of multiple indoor units, and using the average value as the center point of the temperature difference target band; setting the upper limit deviation range of the temperature difference target band, and setting the upper limit threshold of the temperature difference target band according to the average value of the supply and return air temperature difference and the upper limit deviation range; setting the lower limit deviation range of the temperature difference target band, and setting the lower limit threshold of the temperature difference target band according to the average value of the supply and return air temperature difference and the lower limit deviation range.

[0008] The above technical solution has the following advantages or beneficial effects: In this application, the average value of the real-time supply and return air temperature difference of multiple indoor units is used as the center to establish a temperature difference target band. Based on the center, an upper limit deviation range and a lower limit deviation range are set to form a band-shaped interval, which adaptively allows a certain degree of fluctuation, avoids frequent corrections, and maintains the basic operational stability of the air conditioning system. Through the preset temperature difference target band, the processing module does not need to recalculate the theoretical heat load of each air-conditioned room, but only needs to compare the supply and return air temperature difference of each room, that is, the dispersion of the execution result.

[0009] In some embodiments of this application, when the supply air and return air temperature difference deviates from the target temperature difference zone, the processing module is configured to perform the following steps to unidirectionally correct the target overheat of the corresponding indoor unit and generate a corrected target overheat: determining whether the supply air and return air temperature difference is higher than the upper limit threshold of the target temperature difference zone; if so, calling a step adjustment amount to incrementally correct the set target overheat to obtain the corrected target overheat; or, determining whether the supply air and return air temperature difference is lower than the lower limit threshold of the target temperature difference zone; if so, calling a step adjustment amount to decrementally correct the set target overheat to obtain the corrected target overheat.

[0010] The above technical solution has the following advantages or beneficial effects: By utilizing the supply and return air temperature difference to exceed the upper threshold of the target temperature range, and using step adjustment to incrementally correct the set target superheat, the flow rate in the indoor heat exchanger used as an evaporator is reduced, thus reducing the supply and return air temperature difference. This process forms a closed loop, and even after the steady-state stagnation condition is met, it can still automatically eliminate the uneven supply and return air temperature difference in each room. Similarly, by utilizing the supply and return air temperature difference to exceed the lower threshold of the target temperature range, and using step adjustment to incrementally correct the set target superheat, the flow rate in the indoor heat exchanger used as an evaporator is increased, thus raising the supply and return air temperature difference. This process also forms a closed loop, and even after the steady-state stagnation condition is met, it can still automatically eliminate the uneven supply and return air temperature difference in each room.

[0011] In some embodiments of this application, the processing module is configured to perform the following steps to set the target superheat corresponding to the indoor unit based on the indoor load of the air-conditioned room: calculating the temperature difference between the return air temperature and the set temperature of the indoor unit, and using the temperature difference between the return air temperature and the set temperature of the indoor unit as the equivalent indoor load; based on the equivalent indoor load, looking up the target superheat corresponding to the indoor unit in a pre-established equivalent indoor load-target superheat reference table; the equivalent indoor load-target superheat reference table defines a piecewise function to map the equivalent indoor load to the target superheat.

[0012] The above technical solution has the following advantages or beneficial effects: the target superheat corresponding to the current operating condition can be quickly obtained and iterated by looking up a table.

[0013] In some embodiments of this application, the steady-state stagnation condition includes: boundary stagnation condition and / or numerical stagnation condition; the processing module is configured to: determine whether the target superheat is the target superheat threshold in the equivalent indoor load-target superheat reference table; if so, it is determined that the boundary stagnation condition is met; or, the processing module is configured to: obtain the difference between the target superheat of multiple indoor units; if the difference between the target superheat of multiple indoor units is lower than a set deviation threshold, it is determined that the numerical stagnation condition is met.

[0014] The above technical solution has the following advantages or beneficial effects: it can identify the state in which the target superheat of multiple indoor units is consistent or highly similar by using numerical stagnation conditions; and it can identify the state in which the target superheat has reached the limit threshold of the allowable target superheat by using boundary stagnation conditions.

[0015] This application provides an air conditioning system with several embodiments, including multiple indoor units. Each indoor unit includes an indoor heat exchanger, which is fluidly connected to an indoor throttling element. In heating mode, the system's processing module is configured to: set a target subcooling degree for the indoor unit based on the indoor load; adjust the opening of the corresponding indoor throttling element based on the subcooling degree deviation between the target subcooling degree and the real-time subcooling degree, so that the real-time subcooling degree of the indoor unit equals the target subcooling degree; determine whether the target subcooling degree meets a preset steady-state stagnation condition; when the preset steady-state stagnation condition is met, obtain the supply and return air temperature difference of the indoor unit; determine whether the supply and return air temperature difference deviates from a preset temperature difference target band; if so, unidirectionally correct the target subcooling degree of the corresponding indoor unit to generate a corrected target subcooling degree; and adjust the opening of the corresponding indoor throttling element based on the corrected subcooling degree deviation between the corrected target subcooling degree and the real-time subcooling degree, so that the real-time subcooling degree of the corresponding indoor unit equals the corrected target subcooling degree.

[0016] The above technical solution has the following advantages or beneficial effects: The air conditioning system provided in this application, according to the actual operating conditions, no longer follows the principle of unified control based on subcooling deviation in the main control process, but establishes a correction loop to monitor whether the supply air and return air temperature difference belongs to the preset temperature difference target zone; for indoor units where the supply air and return air temperature difference deviates from the preset temperature difference target zone, asymmetric adjustment compensation and secondary distribution are performed; from the perspective of physical characteristics, subcooling is relatively lagging, while supply air and return air temperature difference is sensitive and direct; thus, without changing the overall operation of the air conditioning system, by judging the steady-state stagnation conditions and redistributing the refrigerant through secondary arbitration, the heat exchange capacity of each indoor heat exchanger reaches a true dynamic balance with the instantaneous load and its own state, maintaining the overall comfort of the air conditioning system.

[0017] In some embodiments of this application, the processing module is configured to perform the following steps to establish a preset temperature difference target band: sampling the return air temperature and supply air temperature of the indoor unit; calculating the supply and return air temperature difference between the return air temperature and supply air temperature of the indoor unit; when it is determined that the target subcooling meets the steady-state stagnation condition, calculating the average value of the real-time supply and return air temperature difference of multiple indoor units, and using the average value as the center point of the temperature difference target band; setting the upper limit deviation range of the temperature difference target band, and setting the upper limit threshold of the temperature difference target band according to the average value of the supply and return air temperature difference and the upper limit deviation range; setting the lower limit deviation range of the temperature difference target band, and setting the lower limit threshold of the temperature difference target band according to the average value of the supply and return air temperature difference and the lower limit deviation range.

[0018] The above technical solution has the following advantages or beneficial effects: In this application, the average value of the real-time supply and return air temperature difference of multiple indoor units is used as the center to establish a temperature difference target band. Based on the center, an upper limit deviation range and a lower limit deviation range are set to form a band-shaped interval, which adaptively allows a certain degree of fluctuation, avoids frequent corrections, and maintains the basic operational stability of the air conditioning system. Through the preset temperature difference target band, the processing module does not need to recalculate the theoretical heat load of each air-conditioned room, but only needs to compare the supply and return air temperature difference of each room, that is, the dispersion of the execution result.

[0019] In some embodiments of this application, when the supply air and return air temperature difference deviates from the target temperature difference zone, the processing module is configured to perform the following steps to unidirectionally correct the target subcooling of the corresponding indoor unit and generate a corrected target subcooling: determining whether the supply air and return air temperature difference is higher than the upper limit threshold of the target temperature difference zone; if so, calling a step adjustment amount to incrementally correct the set target subcooling to obtain the corrected target subcooling; or, determining whether the supply air and return air temperature difference is lower than the lower limit threshold of the target temperature difference zone; if so, calling a step adjustment amount to decrementally correct the set target subcooling to obtain the corrected target subcooling.

[0020] The above technical solution has the following advantages or beneficial effects: A closed loop is formed by utilizing the supply and return air temperature difference to exceed the upper threshold of the target temperature range, calling a step adjustment amount to incrementally correct the set target subcooling, reducing the flow rate in the indoor heat exchanger used as a condenser, and reducing the supply and return air temperature difference. Even after meeting the steady-state stagnation condition, it can still automatically eliminate the uneven supply and return air temperature difference between rooms. Another closed loop is formed by utilizing the supply and return air temperature difference to exceed the lower threshold of the target temperature range, calling a step adjustment amount to incrementally correct the set target subcooling, increasing the flow rate in the indoor heat exchanger used as a condenser, and increasing the supply and return air temperature difference. Even after meeting the steady-state stagnation condition, it can still automatically eliminate the uneven supply and return air temperature difference between rooms.

[0021] In some embodiments of this application, the processing module is configured to perform the following steps to set the target subcooling degree corresponding to the indoor unit according to the indoor load of the air-conditioned room: calculate the temperature difference between the return air temperature and the set temperature of the indoor unit, and use the temperature difference between the return air temperature and the set temperature of the indoor unit as the equivalent indoor load; based on the equivalent indoor load, look up the target subcooling degree corresponding to the indoor unit in a pre-established equivalent indoor load-target subcooling degree reference table; the equivalent indoor load-target subcooling degree reference table defines a piecewise function to map the equivalent indoor load to the target subcooling degree.

[0022] The above technical solution has the following advantages or beneficial effects: the target subcooling degree corresponding to the current working condition can be quickly obtained and iterated by looking up a table.

[0023] In some embodiments of this application, the steady-state stagnation condition includes: boundary stagnation condition and / or numerical stagnation condition; the processing module is configured to: determine whether the target subcooling is the target subcooling threshold in the equivalent indoor load-target subcooling reference table; if so, it is determined that the boundary stagnation condition is met; or, the processing module is configured to: obtain the difference between the target subcooling of multiple indoor units; if the difference between the target subcooling of multiple indoor units is lower than a set deviation threshold, it is determined that the numerical stagnation condition is met.

[0024] The above technical solution has the following advantages or beneficial effects: it can identify the state in which the target subcooling of multiple indoor units is consistent or highly similar through numerical stagnation conditions; and it can identify the state in which the target subcooling has reached the limit threshold of the allowable target subcooling through boundary stagnation conditions.

[0025] Other features and advantages of the present invention will become clearer after reading the detailed embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0026] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of an air conditioning system provided in some embodiments of the present invention;

[0028] Figure 2 This is a schematic diagram of the structure of an air conditioning system provided in some embodiments of the present invention;

[0029] Figure 3 to Figure 10 Schematic diagrams of different examples of indoor heat exchangers;

[0030] Figure 11 A flowchart of an air conditioning system provided in some embodiments of the present invention;

[0031] Figure 12 A flowchart of an air conditioning system provided in some embodiments of the present invention;

[0032] Figure 13 A flowchart of an air conditioning system provided in some embodiments of the present invention;

[0033] Figure 14 A flowchart of an air conditioning system provided in some embodiments of the present invention;

[0034] Figure 15 A flowchart of an air conditioning system provided in some embodiments of the present invention;

[0035] Figure 16 A flowchart of an air conditioning system provided in some embodiments of the present invention;

[0036] Figure 17 A flowchart of an air conditioning system provided in some embodiments of the present invention;

[0037] Figure 18 A flowchart of an air conditioning system provided in some embodiments of the present invention;

[0038] Figure 19 A flowchart of an air conditioning system provided in some embodiments of the present invention;

[0039] Figure 20 A flowchart of an air conditioning system provided for some embodiments of the present invention. Detailed Implementation

[0040] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0041] This application designs and provides an air conditioning system, and more specifically, relates to a multi-split air conditioning system.

[0042] From a thermodynamic perspective, the air conditioning system provided in this application uses refrigerant as the working medium and includes an evaporator, a compressor, a condenser, and a throttling device connected in sequence. The refrigeration cycle of the air conditioning system includes a series of processes involving compression, condensation, expansion, and evaporation.

[0043] From a thermodynamic perspective, a low-temperature, low-pressure refrigerant enters the compressor, which compresses it into a high-temperature, high-pressure refrigerant gas and discharges it. The discharged refrigerant gas 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. A throttling device causes the high-temperature, high-pressure liquid refrigerant formed in the condenser to expand into a low-pressure liquid refrigerant. The evaporator evaporates the refrigerant that expanded in the throttling device and returns 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.

[0044] like Figure 1 and Figure 2 As shown, in the air conditioning system, the compressor 101 is the core component. The compressor 101 is used to compress the refrigerant, changing its pressure from low to high, enabling the refrigerant to effectively transfer heat during the refrigeration cycle. The outdoor unit of the air conditioning system refers to the portion including the compressor 101. In addition to the compressor 101, the outdoor unit also includes an outdoor heat exchanger 102. In some embodiments of this application, the outdoor heat exchanger 102 is a finned tube heat exchanger, a plate-fin heat exchanger, or other similar heat exchangers.

[0045] The outdoor unit is also equipped with a switching valve 103, which is used to switch the refrigerant flow direction to switch between cooling and heating modes.

[0046] The outdoor heat exchanger 102 is configured to function as a condenser during cooling operation and as an evaporator during heating operation. The outdoor heat exchanger 102 exchanges heat with the air guided by the outdoor fan, causing the refrigerant flowing in the outdoor heat exchanger 102 to condense or evaporate, resulting in a phase change and heat transfer.

[0047] An oil separator 104 is also installed in the outdoor unit. The oil separator 104 is used to separate the lubricating oil droplets carried by the refrigerant from the discharge of the compressor 101, and to collect and direct the lubricating oil back to the compressor 101, preventing the lubricating oil from migrating with the refrigerant to other parts of the refrigerant cycle, and ensuring that the compressor 101 has a sufficient amount of lubricating oil. The oil separator 104 can achieve separation using separation mechanisms such as gravity settling, inertial separation, and / or centrifugal separation.

[0048] The outdoor unit is also equipped with a gas-liquid separator 105. The gas-liquid separator 105 is located on the suction side of the compressor 101. The gas-liquid separator 105 separates the liquid droplets (containing liquid refrigerant) carried by the gas and liquid phases from the gaseous refrigerant by utilizing the difference in physical properties between the gas and liquid phases, thereby preventing liquid slugging and improving lubricating oil backflow.

[0049] An oil return branch 106 is provided on the lower side of the oil separator 104, and the other end of the oil return branch 106 is connected to the shut-off between the gas-liquid separator 105 and the compressor 101. A capillary tube 107 is provided on the oil return branch 106. Through the oil return branch 106, the oil accumulated at the bottom of the oil separator 104 can continuously flow back to the low-pressure side in a small amount. The capillary tube 107 can prevent sudden pressure changes that could affect the suction temperature and the stable operation of the compressor 101.

[0050] The throttling device includes an outdoor throttling element 108 installed in the outdoor unit, and the outdoor heat exchanger 102 is fluidly connected to the outdoor throttling element 108 (e.g., an electronic expansion valve). In this application, "fluid connection" means that there is a path that allows fluid to flow from one end to the other, including indirect fluid connections between the two through intermediate structures such as pipes or valves.

[0051] The air conditioning system includes multiple indoor units, and each indoor unit includes an indoor heat exchanger.

[0052] In some embodiments of this application, the air conditioning system includes two indoor units, namely a first indoor unit 20 and a second indoor unit 30 as shown in the figure. The first indoor unit 20 is provided with a first indoor heat exchanger 201, and the second indoor unit 30 is provided with a second indoor heat exchanger 302.

[0053] In other embodiments of this application, the air conditioning system may include more indoor units, and there is no further limitation on the number of indoor units.

[0054] The throttling device also includes an indoor throttling element disposed in the indoor unit, and the indoor heat exchanger is fluidly connected to the indoor throttling element. For example, the first indoor heat exchanger 201 is fluidly connected to the first indoor throttling element 202, and the second indoor heat exchanger 302 is fluidly connected to the second indoor throttling element 302.

[0055] The outdoor unit and the indoor unit are connected by a gas-side piping 40 and a liquid-side piping 50. In the outdoor unit, a gas pipe shut-off valve 401 is installed on the gas-side piping 40, and a liquid pipe shut-off valve 501 is installed on the liquid-side piping 50.

[0056] In this application, the air conditioning system includes a sensor module.

[0057] The sensor module includes: an intake pressure sensor 601, an exhaust pressure sensor 602, a liquid pipe temperature sensor, a return air temperature sensor, an supply air temperature sensor, and a gas pipe temperature sensor.

[0058] The suction pressure sensor 601 is used to detect the suction pressure on the suction side of the compressor 101. .

[0059] The exhaust pressure sensor 602 is used to detect the exhaust pressure on the exhaust side of the compressor 101. .

[0060] Liquid line temperature sensors are used to detect the temperature of the liquid side piping in the indoor heat exchanger. For example, the first liquid pipe temperature sensor 503 is used to detect the temperature of the liquid side pipe of the first indoor heat exchanger 201. The second liquid pipe temperature sensor 504 is used to detect the temperature of the liquid side pipe of the second indoor heat exchanger 302. .

[0061] The return air temperature sensor is used to detect the temperature at the return air vent of the indoor unit. For example, the first return air temperature sensor 505 is used to detect the return air temperature at the return air vent of the first indoor unit 20. The second return air temperature sensor 506 is used to detect the return air temperature at the return air vent of the second indoor unit 30. .

[0062] The air supply temperature sensor is used to detect the temperature of the air supply outlet of the indoor unit. For example, the first air supply temperature sensor 507 is used to detect the temperature of the air supply outlet of the first indoor unit 20. The second air supply temperature sensor 508 is used to detect the temperature of the air supply outlet of the second indoor unit 30. .

[0063] The gas pipe temperature sensor is used to detect the temperature of the gas pipes in the indoor heat exchanger. For example, the first duct temperature sensor 509 is used to detect the temperature of the duct of the first indoor heat exchanger 201. The second gas pipe temperature sensor 510 is used to detect the temperature of the gas pipe of the second indoor heat exchanger 302. .

[0064] The air conditioning system also includes a processing module (not shown).

[0065] The processing module is used to monitor and regulate the operating status of the air conditioning system, ensuring its efficient, stable, and safe operation. The processing module includes components such as a processor, volatile memory, non-volatile memory, display device, operating device, communication interface, and drive device, all interconnected via a bus.

[0066] The processing module can be implemented by the air conditioning system's own controller, such as an onboard system built on a microprocessor.

[0067] The processing module can also be implemented by a host computer or a cloud server.

[0068] The processing module can also be implemented by a smart mobile terminal.

[0069] The processing module can also be implemented by combining multiple components such as the air conditioning system's own controller, host computer, cloud server, and smart mobile terminal.

[0070] The processing module communicates with the sensor module. The processing module and the sensor module in the air conditioning system can communicate via LAN (Local Area Network), signal lines (such as Ethernet cable, coaxial cable, fiber optic cable, power line, serial cable, etc.), wireless signals, LTE, 5G, and other networks.

[0071] like Figure 1 As shown, in cooling mode, the high-temperature, high-pressure refrigerant gas discharged from the compressor 101 flows out through the oil separator 104 (the lubricating oil separated by the oil separator 104 returns directly to the suction side of the compressor 101 through the capillary tube 107). The gaseous refrigerant flowing out from the oil separator 104 enters the outdoor heat exchanger 102 through the switching valve 103, and after sufficient heat exchange, it becomes a high-temperature, high-pressure subcooled liquid. When the outdoor throttling element 108 is in its fully open operating range, the liquid refrigerant flowing out of the outdoor throttling element 108 passes through the liquid pipe and then splits into two paths to enter the first indoor unit 20 and the second indoor unit 30. The refrigerant is throttled by the first indoor throttling element 202 and the second indoor throttling element 302, respectively, into a low-temperature, low-pressure two-phase refrigerant. The two-phase refrigerant evaporates in the first indoor heat exchanger 201 and the second indoor heat exchanger 302 into a low-temperature, low-pressure superheated gaseous refrigerant. The low-temperature, low-pressure superheated gaseous refrigerant flows out of the indoor heat exchanger, passes through the gas pipe and the switching valve 103, returns to the gas-liquid separator 105, and then flows into the suction side of the compressor 101, thus completing the refrigeration cycle.

[0072] like Figure 2 As shown, in heating mode, the high-temperature, high-pressure refrigerant gas discharged from compressor 101 flows out through oil separator 104 (the lubricating oil separated by oil separator 104 returns directly to the suction side of compressor 101 through capillary tube 107). The gaseous refrigerant flowing out from oil separator 104 is divided into two paths after passing through switching valve 103 and gas pipe, entering the first indoor unit 20 and the second indoor unit 30. After sufficient heat exchange, the high-temperature, high-pressure gaseous refrigerant is condensed into high-temperature, high-pressure subcooled liquid refrigerant. The first indoor unit throttling element 202 and the second indoor unit throttling element 302 are in the fully open operating range, and the refrigerant entering the liquid pipe is high-pressure subcooled liquid refrigerant. The high-temperature and high-pressure subcooled liquid refrigerant is throttled by the outdoor throttling element 108 into a low-temperature and low-pressure two-phase refrigerant. The two-phase refrigerant evaporates in the outdoor heat exchanger 102 into a low-temperature and low-pressure superheated gaseous refrigerant. The low-temperature and low-pressure superheated gaseous refrigerant flows out of the outdoor heat exchanger 102, passes through the switching valve 103 and returns to the gas-liquid separator 105, and then flows into the suction side of the compressor 101, thus completing the heating cycle.

[0073] For multi-split air conditioning systems, the goal is to achieve a balance between thermal efficiency and user-perceived comfort, with a relatively uniform temperature difference between the supply and return air of each indoor unit to eliminate variations in perceived comfort. User evaluation of air conditioning performance is intuitive; for example, in cooling mode, if the supply air temperature of a room is... The air supply temperature in the other room is Although the temperature in the air-conditioned room can eventually reach However, users may question the performance of an indoor unit with a higher supply air temperature, suspecting a refrigerant shortage or malfunction, leading to complaints. Furthermore, if the supply and return air temperature differences between the indoor units are significant, the air distribution in each air-conditioned room will vary considerably, potentially resulting in some rooms experiencing direct cold air blowing directly onto the head, while others feel no cold air circulation.

[0074] To ensure a relatively uniform temperature difference between the supply and return air of each indoor unit and eliminate differences in perceived temperature.

[0075] In this application, in cooling mode, the processing module is configured to set the target superheat of the indoor unit according to the indoor load of the air-conditioned room, and adjust the opening of the corresponding indoor throttling element based on the deviation between the real-time superheat of the indoor unit and the target superheat, so that the real-time superheat of the indoor unit is equal to the preset target superheat, thereby ensuring that the refrigerant in the indoor heat exchanger, which works as an evaporator, is fully evaporated, which can both ensure heat exchange efficiency and prevent liquid refrigerant backflow from damaging the compressor.

[0076] However, during the aforementioned control process, when the air-conditioned room is under high or low load, the target superheat set for different indoor units based on the real-time load of different air-conditioned rooms may be the same. After adjusting the opening of the indoor throttling element, the real-time superheat of each indoor unit is maintained at the preset target superheat, that is, the same target superheat. However, even if the target superheat is consistent, it does not mean that the actual heat exchange efficiency of each indoor heat exchanger is consistent.

[0077] like Figure 3 and Figure 4 As shown, Figure 3 and Figure 4 The target overheat level corresponding to the indoor unit is... .

[0078] Assumption Figure 3The image shows an indoor heat exchanger under relatively ideal conditions. This heat exchanger has a uniform pressure distribution, a relatively long two-phase region, and its entire surface is maintained at a low, near-constant temperature. In other words, the refrigerant has only just evaporated at the end of this heat exchanger, and most of its area is in the two-phase region. The liquid refrigerant transforms into a gaseous refrigerant, and the heat transfer coefficient of the indoor heat exchanger is high. Therefore, the air supply temperature of this indoor unit is low, resulting in a very cool feeling for the user, demonstrating strong cooling capacity.

[0079] Assumption Figure 4 The image shows an indoor heat exchanger in a relatively suboptimal state. This heat exchanger differs in structure from the one in the relatively ideal state (e.g., more rows of tubes and smaller tube diameters), resulting in a larger pressure loss. According to thermodynamic properties, the pressure of the refrigerant decreases due to frictional resistance as it flows through the tubes. The lower the refrigerant pressure, the lower the corresponding saturation temperature. To achieve the same target superheat at the outlet of the indoor heat exchanger, the refrigerant must enter the superheated zone earlier, reducing the area of ​​the two-phase region within the heat exchanger. In this suboptimal state, the refrigerant evaporates completely in the middle of the heat exchanger, leaving the remaining path entirely as a gaseous superheated zone. This leads to a significant portion of the heat exchanger's surface area undergoing inefficient heat exchange.

[0080] When the airflow and evaporation pressure are the same for both a relatively ideal indoor heat exchanger and a relatively suboptimal indoor heat exchanger, the average surface temperature of the relatively ideal indoor heat exchanger is lower than that of the relatively suboptimal indoor heat exchanger. Therefore, the relatively ideal indoor heat exchanger will perform significantly better than the relatively suboptimal one. Consequently, with the same return air temperature, one indoor unit may have a higher supply air temperature than the other. This discrepancy in perceived temperature leads users to perceive a malfunction or poor cooling performance, resulting in complaints.

[0081] In another example, such as Figure 5 and Figure 6 As shown, Figure 5 and Figure 6 The target overheat level corresponding to the indoor unit is... .

[0082] Assuming in terms of physical structure, Figure 5 and Figure 6 The indoor heat exchangers in both are identical, with the same ratio of two-phase zone to superheated zone and the same evaporation pressure.

[0083] Based on the fundamental formula of thermal equilibrium: ;

[0084] in, This refers to the amount of heat exchanged, that is, the amount of cooling that the refrigerant transfers to the air; Air mass flow rate, also known as air volume; Return air temperature, For supply air temperature, Specific heat capacity.

[0085] Assuming the refrigerant flow distribution is consistent in both indoor heat exchangers, and their physical characteristics are identical when operating as evaporators, then the cooling capacity provided by these two indoor heat exchangers... and They are the same. Assuming the heat exchange, specific heat capacity, and return air temperature are constant, we have: ; ;

[0086] The above formula clearly shows that: air supply temperature With air volume Proportional; air supply temperature With air volume Proportional.

[0087] For low-airflow indoor units, the air is sufficiently cooled through the indoor heat exchanger. Although the cooling capacity provided by the indoor unit is the same, the supply air temperature is low, making the user feel cool and perceive a good cooling effect. For high-airflow indoor units, a large amount of air flows quickly through the indoor heat exchanger, and the individual airflow is cooled in a shorter time, maintaining a higher supply air temperature. Even though the total cooling capacity of the two indoor units is the same, the user may perceive that the air from the high-airflow indoor unit's vent is not cool enough, thus perceiving that the indoor unit as faulty and leading to user complaints. The degree of dirt and blockage in the indoor unit's heat exchanger and filter, the decrease in fan speed due to aging, and instantaneous airflow disturbances in the air-conditioned room can all affect the airflow.

[0088] Therefore, even after adjusting the opening of the indoor throttling element to maintain the real-time superheat of each indoor unit at the preset target superheat—that is, from a control principle perspective, the air conditioning system reaches a steady state where various parameters no longer fluctuate—the system remains stagnant in actual function. It cannot further optimize and eliminate the supply and return air temperature difference. While the superheat closed-loop control has achieved adaptive control, it has not achieved the goal of overall system equilibrium. To address this issue, in some embodiments of this application, in cooling mode, the processing module is configured to execute... Figure 11 The following steps are shown.

[0089] Step S101: Set the target superheat of the indoor unit according to the indoor load of the air-conditioned room. .

[0090] Step S102: Obtain the real-time superheat of the indoor unit. .

[0091] Step S103: Obtain the real-time superheat of the indoor unit. and the target superheat set according to the indoor load. The difference in superheat between them.

[0092] Step S104: Adjust the opening degree of the corresponding indoor throttling element based on the superheat deviation so that the real-time superheat of the indoor unit is equal to the set target superheat.

[0093] Step S105: Determine whether the target superheat of the indoor unit meets the preset steady-state stagnation condition.

[0094] In some embodiments of this application, the steady-state stagnation condition includes: the numerical stagnation condition.

[0095] Numerical stagnation condition refers to a state in which the target superheat of multiple indoor units has become consistent or highly similar.

[0096] When determining whether the target superheat of the indoor unit meets the numerical stagnation condition, the control module is configured as follows:

[0097] The system acquires the difference between the target superheat values ​​of multiple indoor units; it then determines whether this difference is lower than a set deviation threshold. If the difference is lower than the threshold, the numerical stagnation condition is considered met. In other words, if the target superheat values ​​of the indoor units are the same or very similar, the numerical stagnation condition is considered met; otherwise, it is considered not met. The set deviation threshold can be determined under experimental conditions and flexibly adjusted according to actual operating conditions.

[0098] In other embodiments of this application, the steady-state stagnation condition includes: the boundary stagnation condition.

[0099] Boundary stagnation condition refers to a situation where the target superheat has reached the allowable target superheat limit threshold. The original control algorithm will remain at the limit threshold without exceeding it, causing the command to fail.

[0100] Step S106: When the steady-state stagnation condition is met, obtain the supply and return air temperature difference of the indoor unit. Supply and return air temperature difference satisfy It also determines whether the temperature difference between the supply and return air is within the preset temperature difference target zone.

[0101] Step S107: If the supply air and return air temperature difference deviates from the preset temperature difference target zone, then the target superheat of the corresponding indoor unit is corrected in one direction to generate the corrected target superheat.

[0102] Step S108: Based on the real-time superheat of the indoor unit and the deviation between the corrected superheat obtained by one-way correction and the corrected target superheat, adjust the opening of the corresponding indoor throttling element so that the real-time superheat of the corresponding indoor unit is equal to the corrected target superheat.

[0103] Step S109: If the supply air and return air temperature difference belongs to the preset temperature difference target zone, then maintain the opening of the corresponding indoor throttling element based on the superheat deviation, so that the real-time superheat of the indoor unit is equal to the set target superheat.

[0104] In this application, unidirectional correction is a directional compensation for indoor units where the supply and return air temperature difference deviates from a preset temperature difference target zone.

[0105] The air conditioning system provided in this application, based on actual operating conditions, no longer follows the principle of unified control based on superheat deviation in the main control process. Instead, it establishes a correction loop to monitor whether the supply and return air temperature difference falls within the preset temperature difference target zone. For indoor units where the supply and return air temperature difference deviates from the preset temperature difference target zone, it performs asymmetrical adjustment compensation and secondary distribution. From a physical perspective, superheat is relatively lagging, while supply and return air temperature difference is more sensitive and direct. Thus, without changing the overall operation of the air conditioning system, by judging the steady-state stagnation conditions and redistributing the refrigerant through secondary arbitration, the heat exchange capacity of each indoor heat exchanger achieves a true dynamic balance with the instantaneous load and its own state, maintaining the overall comfort of the air conditioning system.

[0106] Compared to directly interfering with the opening of the indoor throttling element, correcting the real-time superheat can achieve refrigerant tilt distribution on the one hand, and maintain the stability of the original adaptive adjustment of the air conditioning system on the other hand.

[0107] The opening degree of the indoor throttling element based on the superheat deviation adjustment, and the opening degree of the indoor throttling element based on the correction of the superheat deviation adjustment, can both adopt the existing PID closed-loop control method, which will not be elaborated here.

[0108] In some embodiments of this application, the processing module is configured to perform, as Figure 12 The following steps are shown to establish a preset temperature difference target zone.

[0109] Step S201: Sample the return air temperature and supply air temperature of the indoor unit.

[0110] Specifically, the return air temperature and supply air temperature of the indoor unit are sampled, and after outliers are removed, a time series of return air temperature and a time series of supply air temperature are established.

[0111] Step S202: Calculate the temperature difference between the return air temperature and the supply air temperature of the indoor unit.

[0112] Specifically, the return air temperature and supply air temperature are paired with the return air temperature time series and the supply air temperature time series at corresponding times, and the supply air temperature difference between the indoor unit's return air temperature and supply air temperature is calculated.

[0113] Step S203: When it is determined that the target superheat of the indoor unit meets the preset steady-state stagnation condition, calculate the average value of the real-time supply and return air temperature difference among multiple indoor units. The average temperature difference between the supply and return air is taken as the center point of the temperature difference target zone.

[0114] Step S204: Set the upper limit deviation range of the temperature difference target band. The upper limit threshold of the temperature difference target zone is set based on the average value and upper limit deviation range of the supply and return air temperature difference. The upper limit deviation range can be a ratio or a specific temperature value, such as any value between 0℃ and 5℃, without further limitation here.

[0115] Step S205: Set the lower limit deviation range of the temperature difference target band. The lower limit threshold of the temperature difference target zone is set based on the average value and lower limit deviation range of the supply and return air temperature difference. The lower limit deviation range can be a ratio or a specific temperature value, such as any value between 0℃ and 5℃, without further limitation here.

[0116] Since the total cooling capacity of a multi-split air conditioning system is determined by the output of the outdoor unit, the ideal supply and return air temperature difference is not constant under different outdoor environments and different total loads. Therefore, in this application, the average value of the real-time supply and return air temperature difference of multiple indoor units is used as the center to establish a temperature difference target band. Based on the center, an upper limit deviation range and a lower limit deviation range are set to form a band-shaped interval, which adaptively allows a certain degree of fluctuation, avoids frequent corrections, and maintains the basic operational stability of the air conditioning system. Through the preset temperature difference target band, the processing module does not need to recalculate the theoretical heat load of each air-conditioned room, but only needs to compare the supply and return air temperature differences of each room, i.e., the dispersion of the execution results.

[0117] In some embodiments of this application, if one or more indoor units are in a state of filter clogging alarm and not reset, when the steady-state stagnation condition is met and a preset temperature difference target band is established, the average value between the real-time supply and return air temperature differences of multiple indoor units is no longer calculated. Instead, the median of the real-time supply and return air temperature differences of multiple indoor units is used as the center point of the temperature difference target band. This avoids the average value being affected by indoor units in extreme faults, thereby improving the overall anti-interference capability of the air conditioning system. Faulty or abnormal indoor units will not affect the determination of other normal units.

[0118] In some embodiments of this application, when the supply air and return air temperature difference deviates from a preset temperature difference target zone, and the target superheat of the corresponding indoor unit is corrected in one direction to generate the corrected target superheat, the following steps are performed: Figure 13 The following steps are shown:

[0119] Step S301: Determine whether the supply and return air temperature difference of the indoor unit is higher than the upper limit threshold of the target temperature difference zone, for example, whether it meets the following requirements: .

[0120] Step S302: If the supply and return air temperature difference of the indoor unit is higher than the upper limit threshold of the temperature difference target zone, the step adjustment amount is called to incrementally correct the set target superheat and obtain the corrected target superheat.

[0121] For example, correcting the target overheating. .

[0122] When the indoor supply and return air temperature difference exceeds the upper limit threshold of the target temperature range, the indoor unit is operating at excessive capacity. A step-by-step adjustment is used to incrementally correct the set target superheat, resulting in a corrected target superheat. After incremental correction, the opening of the corresponding indoor throttling element decreases, reducing the refrigerant flow in the corresponding indoor heat exchanger. This increases the superheat, causing the overall surface temperature of the indoor heat exchanger (acting as an evaporator) to rise. Consequently, the cooling capacity of the indoor unit is suppressed, and the supply and return air temperature difference decreases until it falls within the preset target temperature range. For example:

[0123] Maintain the target overheating level constant.

[0124] In this embodiment, the supply and return air temperature difference is increased by the upper limit threshold of the target temperature difference zone. The step adjustment amount is called to incrementally correct the set target superheat, thereby reducing the flow rate in the indoor heat exchanger used as an evaporator. The process of reducing the supply and return air temperature difference forms a closed loop. After the steady-state stagnation condition is met, the uneven supply and return air temperature difference in each room can still be automatically eliminated.

[0125] In some embodiments of this application, when the supply air and return air temperature difference deviates from a preset temperature difference target zone, and the target superheat of the corresponding indoor unit is corrected in one direction to generate the corrected target superheat, the following steps are performed: Figure 14 The following steps are shown:

[0126] Step S401: Determine whether the supply and return air temperature difference of the indoor unit is lower than the lower limit threshold of the target temperature difference zone, for example, whether it meets the following requirements: .

[0127] Step S402: If the supply and return air temperature difference of the indoor unit is lower than the lower limit threshold of the temperature difference target zone, the step adjustment amount is called to reduce the set target superheat and obtain the corrected target superheat.

[0128] For example, correcting the target overheating. .

[0129] When the indoor supply and return air temperature difference is lower than the lower threshold of the target temperature range, the indoor unit's capacity is insufficient. A step adjustment is used to reduce and correct the set target superheat, thus obtaining the corrected target superheat. After the reduction correction, the opening of the corresponding indoor throttling element increases, increasing the refrigerant flow in the corresponding indoor heat exchanger, reducing the superheat, and lowering the overall surface temperature of the indoor heat exchanger (which acts as an evaporator). This releases the cooling capacity of the indoor unit, increasing the supply and return air temperature difference until it falls within the preset target temperature range, for example:

[0130] Maintain the target overheating level constant.

[0131] In this embodiment, the process of increasing the supply and return air temperature difference by utilizing the fact that the supply and return air temperature difference is lower than the lower limit threshold of the target temperature difference zone, calling the step adjustment amount to reduce the set target superheat, increasing the flow rate in the indoor heat exchanger used as an evaporator, and raising the supply and return air temperature difference forms a closed loop. After the steady-state stagnation condition is met, the uneven supply and return air temperature difference in each room can still be automatically eliminated.

[0132] In the aforementioned adjustment process, the increment or decrement of each adjustment is fixed, and the correction action is triggered only when the indoor supply air and return air temperature difference is higher than the upper threshold of the target temperature difference zone, or lower than the lower threshold of the target temperature difference zone. Furthermore, when the supply air and return air temperature difference falls within the preset target temperature difference zone, the target superheat remains unchanged, allowing the target superheat to accumulate to a certain extent. In this application, the target superheat is not adjusted using PID continuous regulation to avoid the control system from oscillating. Stepped increments and decrements, along with the target temperature difference zone (which can be considered a dead zone), are used. After the fluctuations generated by each correction stabilize, a decision is made on whether to proceed to the next step, providing sufficient buffer time for the air conditioning system. Simultaneously, since the indoor throttling element (electronic expansion valve) is driven by a stepper motor, the operation of the electronic expansion valve can be better matched, ultimately bringing the air conditioning system closer to the optimized operating mode best suited to the current conditions.

[0133] In some embodiments of this application, in cooling mode, the processing module is configured to perform, as follows: Figure 15 The following steps are used to set the target superheat of the indoor unit according to the indoor load of the air-conditioned room.

[0134] Step S501: Sample the return air temperature of the indoor unit and establish a time series of return air temperature.

[0135] Step S502: Sample the set temperature of the indoor unit and establish a time series of the set temperature.

[0136] Step S503: Pair the return air temperature and set temperature at the corresponding time, calculate the temperature difference between the return air temperature and set temperature of the indoor unit, and use the temperature difference between the return air temperature and set temperature of the indoor unit as the equivalent indoor load.

[0137] Step S504: Based on the equivalent indoor load, find the target superheat corresponding to the indoor unit in the pre-established equivalent indoor load-target superheat reference table.

[0138] The equivalent indoor load-target superheat reference table defines a piecewise function that maps equivalent indoor load values ​​to target superheat. The equivalent indoor load value is the input variable, and the target superheat is the output variable; the lower the equivalent indoor load value, the higher the target superheat. If the real-time equivalent indoor load changes, the target superheat will change accordingly.

[0139] An example of an equivalent indoor load-target superheat reference table is shown in the table below:

[0140]

[0141] Determining whether the target superheat of the indoor unit meets the boundary stagnation condition can include:

[0142] Determine whether the target superheat of the indoor unit is the equivalent indoor load - target superheat reference table target superheat threshold.

[0143] If the target superheat of the indoor unit is the target superheat threshold in the equivalent indoor load-target superheat reference table, then the boundary stagnation condition is considered to be met.

[0144] For example, if the target superheat of the indoor unit is 10°C or 1°C, then the target superheat of the indoor unit is considered to meet the steady-state stagnation condition.

[0145] In some embodiments of this application, the real-time superheat of the indoor unit is the temperature difference between the gas pipe temperature sensor and the liquid pipe temperature sensor. That is, it is assumed that the refrigerant, after throttling, is in a two-phase region, and the temperature in the two-phase region is constant under constant pressure. Therefore, the liquid-side pipe temperature is used to represent the saturated evaporation temperature at that pressure. Of course, the pressure can also be detected by a pressure sensor, and the saturation temperature can be obtained from a table based on the pressure to calculate the corresponding superheat. This is well known to those skilled in the art and will not be elaborated here.

[0146] In some embodiments of this application, the suction pressure is maintained at a set value by adjusting the compressor frequency. If the real-time suction pressure is higher than the set value, the compressor operating frequency is increased; if the real-time suction pressure is lower than the set value, the compressor operating frequency is decreased.

[0147] Similarly, for heating mode, if the supply air temperature of a room is... The air supply temperature in the other room is Although the temperature in the air-conditioned room can eventually reach However, users may question the performance of an indoor unit with a lower supply air temperature, suspecting a refrigerant shortage or malfunction, leading to complaints. Furthermore, if the supply and return air temperature differences between the indoor units are significant, the air distribution in each air-conditioned room will vary considerably, potentially resulting in some rooms experiencing direct cold air blowing directly onto the head, while others feel no warm air circulation.

[0148] To ensure a relatively uniform temperature difference between the supply and return air of each indoor unit and eliminate differences in perceived temperature.

[0149] In this application, in heating mode, the processing module is configured to set the target subcooling degree of the indoor unit according to the indoor load of the air-conditioned room, and adjust the opening degree of the corresponding indoor throttling element based on the deviation between the real-time subcooling degree of the indoor unit and the target subcooling degree, so that the real-time subcooling degree of the indoor unit is equal to the preset target subcooling degree, thereby ensuring that the refrigerant in the indoor heat exchanger, which acts as a condenser, accumulates in an appropriate amount and ensures heat exchange efficiency.

[0150] However, during the aforementioned control process, when the air-conditioned room is under high or low load, the target subcooling degree set for different indoor units based on the real-time load of different air-conditioned rooms may be the same. After adjusting the opening of the indoor throttling element, the real-time subcooling degree of each indoor unit is maintained at the preset target subcooling degree, that is, the same target subcooling degree. However, even if the target subcooling degree is consistent, it does not mean that the actual heat exchange efficiency of each indoor heat exchanger is consistent.

[0151] like Figure 7 and Figure 8 As shown, Figure 7 and Figure 8 The target subcooling degree corresponding to the indoor unit is .

[0152] An indoor heat exchanger that functions as a condenser can be understood as consisting of three parts: a superheated zone (containing high-temperature refrigerant gas), a two-phase zone (the zone where heat is released through condensation), and a subcooled zone (where liquid refrigerant cools down and its temperature continues to decrease).

[0153] Assumption Figure 8The middle one is an indoor heat exchanger under relatively ideal conditions. This indoor heat exchanger has a large proportion of superheated zone and two-phase zone, high heat exchange efficiency, and higher average surface temperature of the indoor heat exchanger.

[0154] Assumption Figure 7 The image shows an indoor heat exchanger in a relatively suboptimal state, characterized by a large subcooled area. Although the subcooling reaches the target level, the interior of the heat exchanger is filled with gradually cooling liquid refrigerant, resulting in a lower average surface temperature. At the same inlet air temperature, the suboptimal heat exchanger, due to its lower average surface temperature, produces a significantly lower supply air temperature than the heat exchanger in the relatively ideal state.

[0155] In a relatively suboptimal state, the indoor heat exchanger is actually in a state of capacity suppression, with too much area used for subcooling rather than phase change heat release.

[0156] In another example, such as Figure 9 and Figure 10 As shown, Figure 9 and Figure 10 The target subcooling degree corresponding to the indoor unit is .

[0157] Assuming in terms of physical structure, Figure 9 and Figure 10 The indoor heat exchangers in all of them are the same.

[0158] Based on the fundamental formula of thermal equilibrium: ;

[0159] in, For heat exchange, that is, the heat generated by the refrigerant transferred to the air; Air mass flow rate, also known as air volume; Return air temperature, For supply air temperature, Specific heat capacity.

[0160] Assuming the refrigerant flow distribution is identical in both indoor heat exchangers, and their physical characteristics are identical when operating as condensers, then the heating capacity provided by these two indoor heat exchangers... and They are the same. Assuming the heat exchange, specific heat capacity, and return air temperature are constant, we have: ; ;

[0161] The above formula clearly shows that: air supply temperature With air volume Proportional; air supply temperature With air volume Proportional.

[0162] For low-airflow indoor units, the air is fully heated through the indoor heat exchanger. Although the indoor unit provides the same heating capacity, the higher supply air temperature makes the user feel the temperature better and perceive it as having a better heating effect. For high-airflow indoor units, a large amount of air flows quickly through the indoor heat exchanger, resulting in a shorter heating time for each unit and a relatively lower supply air temperature. Even if both indoor units have the same total heating capacity, the user may perceive that the air from the high-airflow unit's vent is not hot enough, leading them to believe that the unit is faulty and potentially causing a complaint. The degree of dirt or blockage in the indoor unit's heat exchanger and filter, the decrease in fan speed due to aging, and instantaneous airflow disturbances in the air-conditioned room can all affect the airflow.

[0163] Therefore, even after adjusting the opening of the indoor throttling element so that the real-time subcooling of each indoor unit is maintained at the preset target subcooling, that is, from the perspective of control principle, the air conditioning system reaches a steady state and the various parameters no longer fluctuate, the air conditioning system is in a stagnant state in actual function, and cannot further optimize and eliminate the supply and return air temperature difference. The subcooling closed loop has completed adaptive control, but has not achieved the goal of overall balance of the air conditioning system.

[0164] To address this issue, in some embodiments of this application, in heating mode, the processing module is configured to perform, as follows: Figure 16 The following steps are shown.

[0165] Step S601: Set the target subcooling level of the indoor unit according to the indoor load of the air-conditioned room. .

[0166] Step S602: Obtain the real-time subcooling degree of the indoor unit. .

[0167] Step S603: Obtain the real-time subcooling degree of the indoor unit. and the target subcooling degree set according to the indoor load. The difference in supercooling between them.

[0168] Step S604: Adjust the opening degree of the corresponding indoor throttling element based on the subcooling deviation so that the real-time subcooling of the indoor unit is equal to the set target subcooling.

[0169] Step S605: Determine whether the target subcooling of the indoor unit meets the preset steady-state stagnation condition.

[0170] In some embodiments of this application, the steady-state stagnation condition may include: a numerical stagnation condition.

[0171] Numerical stagnation condition refers to a state in which the target subcooling of multiple indoor units has become consistent or highly similar.

[0172] When determining whether the target subcooling degree of the indoor unit meets the numerical stagnation condition, the control module is configured as follows:

[0173] The system acquires the difference between the target subcooling values ​​of multiple indoor units; it then determines whether this difference is lower than a set deviation threshold. If the difference is lower than the set deviation threshold, the system is considered to have met the numerical stagnation condition. In other words, if the target subcooling values ​​of the indoor units are the same or very similar, the numerical stagnation condition is considered met; otherwise, it is considered not met. The set deviation threshold can be determined under experimental conditions based on actual needs and flexibly adjusted according to actual operating conditions.

[0174] In other embodiments of this application, the steady-state stagnation condition includes: the boundary stagnation condition.

[0175] Boundary stagnation condition refers to the situation where the target supercooling has reached the limit threshold of the allowable target supercooling. The original control algorithm will remain at the limit threshold and will not break through it, causing the command to fail.

[0176] Step S606: When the steady-state stagnation condition is met, obtain the supply and return air temperature difference of multiple indoor units. Supply and return air temperature difference satisfy It also determines whether the temperature difference between the supply and return air is within the preset temperature difference target zone.

[0177] Step S607: If the supply air and return air temperature difference deviates from the preset temperature difference target zone, then the target subcooling degree of the corresponding indoor unit is corrected in one direction to generate the corrected target subcooling degree.

[0178] Step S608: Based on the real-time subcooling of the indoor unit and the subcooling deviation between the corrected target subcooling obtained by unidirectional correction, adjust the opening of the corresponding indoor throttling element so that the real-time subcooling of the indoor unit is equal to the corrected target subcooling.

[0179] Step S609: If the supply air and return air temperature difference belongs to the preset temperature difference target zone, then maintain the opening of the corresponding indoor throttling element based on the subcooling deviation, so that the real-time subcooling of the indoor unit is equal to the set target subcooling.

[0180] In this application, unidirectional correction is a directional compensation for indoor units where the supply and return air temperature difference deviates from a preset temperature difference target zone.

[0181] The air conditioning system provided in this application, based on actual operating conditions, no longer follows the principle of uniformly executing control based on subcooling deviation in the main control process. Instead, it establishes a correction loop to monitor whether the supply and return air temperature difference falls within the preset temperature difference target zone. For indoor units where the supply and return air temperature difference deviates from the preset temperature difference target zone, it performs asymmetrical adjustment compensation and secondary distribution. From a physical perspective, subcooling is relatively lagging, while supply and return air temperature difference is more sensitive and direct. Thus, without changing the overall operation of the air conditioning system, by judging steady-state stagnation conditions and redistributing refrigerant through secondary arbitration, the heat exchange capacity of each indoor heat exchanger achieves a true dynamic balance with the instantaneous load and its own state, maintaining the overall comfort of the air conditioning system.

[0182] Compared to directly interfering with the opening of the indoor throttling element, correcting the real-time subcooling can achieve refrigerant tilt distribution on the one hand, and maintain the stability of the original adaptive adjustment of the air conditioning system on the other hand.

[0183] The opening degree of the indoor throttling element based on the subcooling deviation adjustment, and the opening degree of the indoor throttling element based on the correction of the subcooling deviation adjustment, can both adopt the existing PID closed-loop control method, which will not be elaborated here.

[0184] In some embodiments of this application, the processing module is configured to perform, as Figure 17 The following steps are shown to establish a preset temperature difference target zone.

[0185] Step S701: Sample the return air temperature and supply air temperature of the indoor unit.

[0186] Specifically, the return air temperature and supply air temperature of the indoor unit are sampled, and after outliers are removed, a time series of return air temperature and a time series of supply air temperature are established.

[0187] Step S702: Calculate the temperature difference between the return air temperature and the supply air temperature of the indoor unit.

[0188] Specifically, the return air temperature and supply air temperature are paired with the return air temperature time series and the supply air temperature time series at corresponding times, and the supply air temperature difference between the indoor unit's return air temperature and supply air temperature is calculated.

[0189] Step S703: When it is determined that the target subcooling of the indoor unit meets the preset steady-state stagnation condition, calculate the average value of the real-time supply and return air temperature difference among multiple indoor units. The average temperature difference between the supply and return air is taken as the center point of the temperature difference target zone.

[0190] Step S704: Set the upper limit deviation range of the temperature difference target band. The upper limit threshold of the temperature difference target zone is set based on the average value and upper limit deviation range of the supply and return air temperature difference. The upper limit deviation range can be a ratio or a specific temperature value, such as any value between 0℃ and 5℃, without further limitation here.

[0191] Step S705: Set the lower limit deviation range of the temperature difference target band. The lower limit threshold of the temperature difference target zone is set based on the average value and lower limit deviation range of the supply and return air temperature difference. The lower limit deviation range can be a ratio or a specific temperature value, such as any value between 0℃ and 5℃, without further limitation here.

[0192] Since the total heating capacity of a multi-split air conditioning system is determined by the output of the outdoor unit, the ideal supply and return air temperature difference is not constant under different outdoor environments and different total loads. Therefore, in this application, the average value of the real-time supply and return air temperature difference of multiple indoor units is used as the center to establish a temperature difference target band. Based on the center, an upper limit deviation range and a lower limit deviation range are set to form a band-shaped interval, which adaptively allows a certain degree of fluctuation, avoids frequent corrections, and maintains the basic operational stability of the air conditioning system. Through the preset temperature difference target band, the processing module does not need to recalculate the theoretical heat load of each air-conditioned room, but only needs to compare the supply and return air temperature differences of each room, i.e., the dispersion of the execution results.

[0193] In some embodiments of this application, if one or more indoor units are in a state of filter clogging alarm and not reset, when the steady-state stagnation condition is met and a preset temperature difference target band is established, the average value between the real-time supply and return air temperature differences of multiple indoor units is no longer calculated. Instead, the median of the real-time supply and return air temperature differences of multiple indoor units is used as the center point of the temperature difference target band. This avoids the average value being affected by indoor units in extreme faults, thereby improving the overall anti-interference capability of the air conditioning system. Faulty or abnormal indoor units will not affect the determination of other normal units.

[0194] In some embodiments of this application, when the supply air and return air temperature difference deviates from a preset temperature difference target zone, and the target subcooling of the corresponding indoor unit is corrected in one direction to generate the corrected target subcooling, the following steps are performed: Figure 18 The following steps are shown:

[0195] Step S801: Determine whether the supply and return air temperature difference of the indoor unit is higher than the upper limit threshold of the target temperature difference zone, for example, whether it meets the following requirements: .

[0196] Step S802: If the supply and return air temperature difference of the indoor unit is higher than the upper limit threshold of the temperature difference target zone, the step adjustment amount is called to incrementally correct the set target subcooling, and the corrected target subcooling is obtained.

[0197] For example, correcting the target supercooling. .

[0198] When the indoor supply air and return air temperature difference exceeds the upper limit threshold of the target temperature difference zone, the indoor unit's capacity is excessive. A step-by-step adjustment is used to incrementally correct the set target subcooling, resulting in a corrected target subcooling. After incremental correction, the opening of the corresponding indoor throttling element decreases. This decrease in the opening of the indoor throttling element increases the outlet resistance of the indoor heat exchanger, which acts as a condenser. Refrigerant accumulates in the indoor heat exchanger, its flow velocity slows, refrigerant flow rate decreases, subcooling increases, total mass flow rate decreases, and the liquid zone occupies a larger heat exchange area. The overall surface temperature of the indoor heat exchanger, acting as a condenser, decreases, thus suppressing the cooling capacity of the indoor unit. The supply air and return air temperature difference decreases until it falls within the preset target temperature difference zone. For example:

[0199] Maintain the target undercooling constant.

[0200] In this embodiment, a closed loop is formed by utilizing the process of supply air and return air temperature difference being higher than the upper limit threshold of the target temperature difference zone, calling step adjustment amount to incrementally correct the set target subcooling, reducing the flow rate in the indoor heat exchanger used as a condenser, and reducing the supply air and return air temperature difference. After the steady-state stagnation condition is met, the uneven supply air and return air temperature difference in each room can still be automatically eliminated.

[0201] In some embodiments of this application, when the supply air and return air temperature difference deviates from a preset temperature difference target zone, and the target subcooling of the corresponding indoor unit is corrected in one direction to generate the corrected target subcooling, the following steps are performed: Figure 19 The following steps are shown:

[0202] Step S901: Determine whether the supply and return air temperature difference of the indoor unit is lower than the lower limit threshold of the target temperature difference zone, for example, whether it meets the following requirements: .

[0203] Step S902: If the supply and return air temperature difference of the indoor unit is lower than the lower limit threshold of the temperature difference target zone, the step adjustment amount is called to reduce and correct the set target subcooling, so as to obtain the corrected target subcooling.

[0204] For example, correcting the target supercooling. .

[0205] When the indoor supply and return air temperature difference is lower than the lower threshold of the target temperature range, the indoor unit's capacity is insufficient. A step adjustment is used to reduce and correct the set target subcooling, thus achieving the corrected target subcooling. After this reduction, the opening of the corresponding indoor throttling element increases, increasing the refrigerant flow in the corresponding indoor heat exchanger, reducing the subcooling, and raising the overall surface temperature of the indoor heat exchanger (which acts as a condenser). This releases the cooling capacity of the indoor unit, increasing the supply and return air temperature difference until it falls within the preset target temperature range, for example:

[0206] Maintain the target undercooling constant.

[0207] In this embodiment, by utilizing the fact that the supply air and return air temperature difference is lower than the lower limit threshold of the temperature difference target zone, the step adjustment amount is called to reduce and correct the set target subcooling, and the flow rate in the indoor heat exchanger used as a condenser is increased. The process of increasing the supply air and return air temperature difference forms a closed loop. After the steady-state stagnation condition is met, the uneven supply air and return air temperature difference in each room can still be automatically eliminated.

[0208] In the aforementioned adjustment process, the increment or decrement of each adjustment is fixed, and the correction action is triggered only when the indoor supply air and return air temperature difference is higher than the upper threshold of the target temperature difference zone, or lower than the lower threshold of the target temperature difference zone. Furthermore, when the supply air and return air temperature difference falls within the preset target temperature difference zone, the target subcooling is kept constant, allowing the target subcooling to accumulate to a certain extent. In this application, the target subcooling is not adjusted using PID continuous regulation to avoid the control system falling into oscillation. Stepped increments and decrements, along with the target temperature difference zone (which can be considered a dead zone), are used. After the fluctuations generated by each correction stabilize, a decision is made on whether to proceed to the next step, providing sufficient buffer time for the air conditioning system. Simultaneously, since the indoor throttling element (electronic expansion valve) is driven by a stepper motor, its operation can be better matched, ultimately bringing the air conditioning system closer to the optimized operating mode best suited to the current conditions.

[0209] In some embodiments of this application, in heating mode, the processing module is configured to perform, as follows: Figure 20 The following steps are shown to set the target subcooling level of the indoor unit according to the indoor load of the air-conditioned room.

[0210] Step S1001: Sample the return air temperature of the indoor unit and establish a time series of return air temperature.

[0211] Step S1002: Sample the set temperature of the indoor unit and establish a time series of the set temperature.

[0212] Step S1003: Pair the return air temperature and set temperature at the corresponding time, calculate the temperature difference between the return air temperature and set temperature of the indoor unit, and use the temperature difference between the return air temperature and set temperature of the indoor unit as the equivalent indoor load.

[0213] Step S1004: Based on the equivalent indoor load and the pre-established equivalent indoor load-target subcooling reference table, set the target subcooling corresponding to the indoor unit.

[0214] The equivalent indoor load-target subcooling reference table defines a piecewise function that maps equivalent indoor load values ​​to target subcooling. The equivalent indoor load value is the input variable, and the target subcooling is the output variable; the lower the equivalent indoor load value, the higher the target subcooling. If the real-time equivalent indoor load changes, the target subcooling will change accordingly.

[0215] An example of an equivalent indoor load-target subcooling reference table is shown in the table below:

[0216]

[0217] Determining whether the target subcooling of the indoor unit meets the numerical stagnation condition can include:

[0218] Determine whether the target subcooling of the indoor unit is the equivalent indoor load - target subcooling reference table target subcooling threshold.

[0219] If the target subcooling of the indoor unit is the target subcooling threshold in the equivalent indoor load-target subcooling reference table, then the boundary stagnation condition is considered to be met.

[0220] For example, if the target subcooling of the indoor unit is 20°C or 1°C, then the target subcooling of the indoor unit is considered to meet the boundary stagnation condition.

[0221] In some embodiments of this application, the real-time subcooling of the indoor unit is the temperature difference between the compressor discharge pressure corresponding to the saturation temperature and the liquid pipe temperature sensor. This is well known to those skilled in the art and will not be elaborated further here.

[0222] In some embodiments of this application, the discharge pressure is maintained at a set value by adjusting the frequency of the compressor. If the real-time discharge pressure is higher than the set value of the discharge pressure, the operating frequency of the compressor is reduced; if the real-time discharge pressure is lower than the set value of the discharge pressure, the operating frequency of the compressor is increased.

[0223] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0224] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An air conditioning system, comprising: a plurality of indoor units, comprising: an indoor heat exchanger fluidly connected to an indoor throttling element; a processing module configured to, in a cooling mode, set a target superheat degree for the indoor unit according to an indoor load, and adjust an opening degree of the corresponding indoor throttling element based on a superheat degree deviation between the target superheat degree and a real-time superheat degree, so that the real-time superheat degree of the indoor unit is equal to the target superheat degree; characterized in that the processing module is further configured to: determine whether the target superheat degree satisfies a preset steady-state stagnation condition; when the preset steady-state stagnation condition is satisfied, obtain a supply-return air temperature difference of the indoor unit; determine whether the supply-return air temperature difference deviates from a preset temperature difference target band; if so, unidirectionally correct the target superheat degree of the corresponding indoor unit to generate a corrected target superheat degree; adjust the opening degree of the corresponding indoor throttling element based on a corrected superheat degree deviation between the corrected target superheat degree and the real-time superheat degree, so that the real-time superheat degree of the corresponding indoor unit is equal to the corrected target superheat degree.

2. The air conditioning system of claim 1, wherein: the processing module is configured to perform the following steps to establish the preset temperature difference target band: sample a return air temperature and a supply air temperature of the indoor unit; calculate a supply-return air temperature difference between the return air temperature and the supply air temperature of the indoor unit; when it is determined that the target superheat degree satisfies the steady-state stagnation condition, calculate a mean value of real-time supply-return air temperature differences of the plurality of indoor units, and take the mean value as a center point of the temperature difference target band; set an upper deviation range of the temperature difference target band, and set an upper threshold of the temperature difference target band according to the mean value of the supply-return air temperature difference and the upper deviation range; set a lower deviation range of the temperature difference target band, and set a lower threshold of the temperature difference target band according to the mean value of the supply-return air temperature difference and the lower deviation range.

3. The air conditioning system of claim 2, wherein: when the supply-return air temperature difference deviates from the temperature difference target band, the processing module is configured to perform the following steps to unidirectionally correct the target superheat degree of the corresponding indoor unit to generate a corrected target superheat degree: determine whether the supply-return air temperature difference is higher than the upper threshold of the temperature difference target band; if so, call a step adjustment amount to incrementally correct the set target superheat degree to obtain the corrected target superheat degree; or, determine whether the supply-return air temperature difference is lower than the lower threshold of the temperature difference target band; if so, call the step adjustment amount to decrementally correct the set target superheat degree to obtain the corrected target superheat degree.

4. The air conditioning system of any one of claims 1 to 3, wherein: the processing module is configured to perform the following steps to set the target superheat degree of the indoor unit according to an indoor load of an air conditioning room: calculate a temperature difference between a return air temperature of the indoor unit and a set temperature, and take the temperature difference between the return air temperature of the indoor unit and the set temperature as an equivalent indoor load; based on the equivalent indoor load, look up the target superheat degree corresponding to the indoor unit in a pre-established equivalent indoor load-target superheat degree reference table; the equivalent indoor load-target superheat degree reference table defines a segmented function to map the equivalent indoor load to the target superheat degree.

5. The air conditioning system of claim 4, wherein: the steady-state stagnation condition comprises a boundary stagnation condition and / or a numerical stagnation condition; the processing module is configured to determine whether the target superheat degree is a target superheat degree threshold in the equivalent indoor load-target superheat degree reference table, and determine that the boundary stagnation condition is satisfied if the target superheat degree is the target superheat degree threshold; or, the processing module is configured to obtain a difference between target superheat degrees of the multiple indoor units, and determine that the numerical stagnation condition is satisfied if the difference between target superheat degrees of the multiple indoor units is lower than a set deviation threshold.

6. An air conditioning system, comprising: a plurality of indoor units, comprising: an indoor heat exchanger fluidly connected to an indoor throttling element; a processing module configured to, in a heating mode, set a target subcooling degree for the indoor unit according to an indoor load, and adjust an opening degree of the corresponding indoor throttling element based on a subcooling degree deviation between the target subcooling degree and a real-time subcooling degree, so that the real-time subcooling degree of the indoor unit is equal to the target subcooling degree; characterized in that the processing module is further configured to: determine whether the target subcooling degree satisfies a preset steady-state stagnation condition; obtain a supply-return air temperature difference of the indoor unit when the preset steady-state stagnation condition is satisfied; determine whether the supply-return air temperature difference deviates from a preset temperature difference target band, and unidirectionally correct the target subcooling degree of the corresponding indoor unit to generate a corrected target subcooling degree if the supply-return air temperature difference deviates from the temperature difference target band; adjust the opening degree of the corresponding indoor throttling element based on a corrected subcooling degree deviation between the corrected target subcooling degree and the real-time subcooling degree, so that the real-time subcooling degree of the corresponding indoor unit is equal to the corrected target subcooling degree.

7. The air conditioning system of claim 6, wherein: the processing module is configured to perform the following steps to establish the preset temperature difference target band: sample a return air temperature and a supply air temperature of the indoor unit; calculate a supply-return air temperature difference between the return air temperature and the supply air temperature of the indoor unit; calculate a mean value of real-time supply-return air temperature differences of the multiple indoor units when it is determined that the target subcooling degree satisfies the steady-state stagnation condition, and take the mean value as a center point of the temperature difference target band; set an upper deviation range of the temperature difference target band, and set an upper threshold of the temperature difference target band according to the mean value of the supply-return air temperature difference and the upper deviation range; set a lower deviation range of the temperature difference target band, and set a lower threshold of the temperature difference target band according to the mean value of the supply-return air temperature difference and the lower deviation range.

8. The air conditioning system of claim 7, wherein: when the supply-return air temperature difference deviates from the temperature difference target band, the processing module is configured to perform the following steps to unidirectionally correct the target subcooling degree of the corresponding indoor unit to generate a corrected target subcooling degree: determine whether the supply-return air temperature difference is higher than the upper threshold of the temperature difference target band; if the supply-return air temperature difference is higher than the upper threshold of the temperature difference target band, a step adjustment amount is called to incrementally correct the set target subcooling degree to obtain the corrected target subcooling degree; or, determine whether the supply-return air temperature difference is lower than the lower threshold of the temperature difference target band; if the supply-return air temperature difference is lower than the lower threshold of the temperature difference target band, the step adjustment amount is called to decrementally correct the set target subcooling degree to obtain the corrected target subcooling degree.

9. The air conditioning system of any one of claims 6 to 8, wherein: The processing module is configured to perform the following steps to set a target supercooling degree corresponding to the indoor unit according to the indoor load of the air-conditioned room: calculating a temperature difference between the return air temperature of the indoor unit and the set temperature, taking the temperature difference between the return air temperature of the indoor unit and the set temperature as an equivalent indoor load; based on the equivalent indoor load, searching for a target supercooling degree corresponding to the indoor unit in a pre-established equivalent indoor load-target supercooling degree reference table; the equivalent indoor load-target supercooling degree reference table defines a segmented function to map the equivalent indoor load to the target supercooling degree.

10. The air conditioning system of claim 9, wherein: the steady-state stagnation condition comprises a boundary stagnation condition and / or a numerical stagnation condition; the processing module is configured to determine whether the target supercooling degree is a target supercooling degree threshold in the equivalent indoor load-target supercooling degree reference table, and if so, determine that the boundary stagnation condition is satisfied; or, the processing module is configured to obtain a difference between target supercooling degrees of multiple indoor units, and if the difference between target supercooling degrees of multiple indoor units is lower than a set deviation threshold, determine that the numerical stagnation condition is satisfied.

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