Electronic expansion valve group control method and device, air conditioner and storage medium

Abstract

The application relates to an electronic expansion valve group control method and device, an air conditioner and a storage medium, the air conditioner being an energy-saving air conditioner, the method comprising the following steps: determining a required load rate of an air handling unit, and obtaining a load rate interval in which the required load rate is located; determining a working mode of the electronic expansion valve group according to the load rate interval; and controlling a first opening degree of a first electronic expansion valve and / or a second opening degree of a second electronic expansion valve according to the working mode. Thus, the first and second electronic expansion valves with different diameters are connected in parallel to form a valve group, and corresponding working modes and valve opening degrees are matched according to the interval in which the required load rate of the air handling unit is located, so that the precise adjustment of refrigerant flow in a full load interval can be realized, the problems of poor control precision of the valve opening degree under low load and noise generated by the valve opening degree under low load can be effectively solved, the high load and large flow demand can be met, and the system regulation stability and operation comfort are improved.

Description

Technical Field

[0001] This application relates to the field of smart home technology, and in particular to an electronic expansion valve group control method, device, air conditioner and storage medium. Background Technology

[0002] In the fresh air treatment of high-volume, high-load environments such as shopping malls and office buildings, air handling units (AHUs) are often connected to multi-split systems as terminal devices to meet environmental control requirements. The KIT, as a core component for connecting the AHU to a multi-split system, consists of an electronic expansion valve (EXV) and a control board. It adjusts the refrigerant flow in real time to match the system's capacity requirements, thereby controlling the AHU's output capacity. The combination of the AHU and KIT is equivalent to the operation of a conventional indoor unit.

[0003] In existing AHU-KIT designs, a single EXV configuration is typically used. However, for high-load areas with large cooling capacity requirements, using a large-diameter EXV would present cost and reliability challenges. Therefore, a dual-diameter EXV design is often adopted, such as replacing a single 6.0-diameter EXV with two 3.0-diameter EXVs. This satisfies the load requirements while providing redundant operation in case of single-valve failure, thus preventing the KIT from completely failing.

[0004] However, both the single EXV and dual EXV solutions mentioned above have common defects: when the AHU is in the low-load operating range, the required refrigerant flow rate is significantly reduced, which causes the EXV to maintain a very small opening. This not only results in insufficient refrigerant flow control accuracy, but also easily generates operating noise. This noise can have an adverse effect on people in a quiet environment, thus restricting the application experience of AHU-KIT in low-load scenarios. Summary of the Invention

[0005] To address the common drawbacks of both single-EXV and dual-EXV solutions mentioned above—that the required refrigerant flow rate decreases significantly when the AHU is operating at low loads, forcing the EXV to maintain a very small opening—this not only results in insufficient refrigerant flow control accuracy but also generates operating noise. This noise can negatively impact occupants in quiet environments, thus limiting the AHU-KIT's performance in low-load scenarios, this application provides an electronic expansion valve group control method, device, air conditioner, and storage medium. The air conditioner is an energy-saving type. The specific technical solution is as follows: In a first aspect, this application provides a method for controlling an electronic expansion valve assembly, wherein the electronic expansion valve assembly includes at least a first electronic expansion valve and a second electronic expansion valve arranged in parallel, wherein the diameters of the first electronic expansion valve and the second electronic expansion valve are different, and the method includes: Determine the demand load rate of the air handling unit and obtain the load rate range in which the demand load rate falls; The operating mode of the electronic expansion valve assembly is determined based on the load rate range. According to the operating mode, control the first opening degree of the first electronic expansion valve and / or the second opening degree of the second electronic expansion valve.

[0006] In an optional implementation, determining the demand load factor of the air handling unit includes: Determine the refrigerant flow requirement of the air handling unit and obtain the rated cooling capacity of the air handling unit; The ratio between the required refrigerant flow rate and the rated cooling capacity is determined as the demand load rate of the air handling unit.

[0007] In an optional implementation, determining the refrigerant flow requirement of the air handling unit includes: Obtain the current air volume in the air handling unit and determine the density of the air at the coil inlet in the air handling unit; Determine the first specific enthalpy value of the air at the coil inlet and the second specific enthalpy value of the air at the coil outlet in the air handling unit; The refrigerant flow requirement of the air handling unit is determined based on the current air volume, the density, the first specific enthalpy value, and the second specific enthalpy value.

[0008] In an optional implementation, determining the density of the air at the coil inlet of the air handling unit includes: The temperature and humidity at the coil inlet of the air handling unit are obtained, and the density of the air at the coil inlet of the air handling unit is determined based on the temperature and humidity. Determining the first specific enthalpy value of the air inlet to the coil and the second specific enthalpy value of the air outlet to the coil in the air handling unit includes: The first dry-bulb temperature and the first wet-bulb temperature of the air at the coil inlet of the air handling unit are obtained. The first specific enthalpy value of the air inlet to the coil in the air handling unit is determined based on the first dry-bulb temperature and the first wet-bulb temperature. Obtain the second dry-bulb temperature and the second wet-bulb temperature of the air at the coil outlet of the air handling unit; The second specific enthalpy value of the air at the coil outlet of the air handling unit is determined based on the second dry-bulb temperature and the second wet-bulb temperature.

[0009] In an optional implementation, determining the refrigerant flow requirement of the air handling unit based on the current air volume, the density, the first specific enthalpy value, and the second specific enthalpy value includes: Input the current air volume, the density, the first specific enthalpy value, and the second specific enthalpy value into the refrigerant demand flow calculation formula to obtain the refrigerant demand flow of the air handling unit; The formula for calculating the required refrigerant flow rate includes: ; The The refrigerant required flow rate is V, where V is the current air volume. For the density, the For the first specific enthalpy value, the This is the second specific enthalpy value.

[0010] In one optional embodiment, the diameter of the first electronic expansion valve is smaller than the diameter of the second electronic expansion valve. Determining the operating mode of the electronic expansion valve assembly based on the load rate range includes: When the load rate range is the first load rate range, the first mode is determined as the working mode of the electronic expansion valve assembly; In the first mode, the first electronic expansion valve is operational, and the second electronic expansion valve is closed. When the load rate range is the second load rate range, the second mode is determined as the operating mode of the electronic expansion valve assembly; In the second mode, the first electronic expansion valve is closed and the second electronic expansion valve is open. When the load rate range is the third load rate range, the third mode is determined as the operating mode of the electronic expansion valve assembly; In the third mode, the first electronic expansion valve and the second electronic expansion valve work together.

[0011] In an optional implementation, determining the total refrigerant flow demand based on the refrigerant flow demand includes: Obtain the enthalpy difference of the refrigerant at the inlet and outlet of the evaporator, and divide the required refrigerant flow rate by the enthalpy difference to obtain the total required refrigerant flow rate.

[0012] In an optional implementation, controlling the first opening degree of the first electronic expansion valve according to the total refrigerant demand flow rate includes: Obtain the set target superheat and the first mapping relationship corresponding to the first electronic expansion valve. The first mapping relationship records the mapping relationship between the opening degree and the flow rate and superheat. Based on the target superheat and the total refrigerant flow rate, the first target opening degree is obtained by querying the first mapping relationship; Adjust the first opening degree of the first electronic expansion valve to the first target opening degree.

[0013] In an optional implementation, controlling the second opening degree of the second electronic expansion valve according to the total refrigerant demand flow rate includes: Obtain the set target superheat and the second mapping relationship corresponding to the second electronic expansion valve. The second mapping relationship records the mapping relationship between the opening degree and the flow rate and superheat. Based on the target superheat and the total refrigerant flow rate, the second target opening degree is obtained by querying the second mapping relationship. Adjust the second opening degree of the second electronic expansion valve to the second target opening degree.

[0014] In an optional implementation, controlling the first opening degree of the first electronic expansion valve and the second opening degree of the second electronic expansion valve according to the total refrigerant demand flow rate includes: Obtain the distribution ratio of the second electronic expansion valve, multiply the total refrigerant demand flow rate by the distribution ratio, and obtain the main refrigerant distribution flow rate; Obtain the set target superheat and the second mapping relationship corresponding to the second electronic expansion valve. The second mapping relationship records the mapping relationship between the opening degree and the flow rate and superheat. Based on the target superheat and the main refrigerant flow rate, the second mapping relationship is queried to obtain the third target opening degree; Adjust the second opening degree of the second electronic expansion valve to the third target opening degree; Subtracting the main refrigerant flow rate from the total refrigerant demand flow rate yields the auxiliary refrigerant flow rate. Obtain the first mapping relationship corresponding to the first electronic expansion valve, and record the mapping relationship between opening degree and flow rate and superheat in the first mapping relationship; Based on the target superheat and the refrigerant auxiliary flow rate, the first mapping relationship is queried to obtain the fourth target opening degree; The first opening degree of the first electronic expansion valve is adjusted to the fourth target opening degree.

[0015] In an optional implementation, after determining the operating mode of the electronic expansion valve assembly, the method further includes: Obtain the first load switching threshold corresponding to the first mode, and determine the first product between the first load switching threshold and the first hysteresis ratio; If the demand load rate exceeds the sum of the first load switching threshold and the first product within a preset time period, the first mode will be switched to the second mode. or, Obtain the second load switching threshold corresponding to the second mode, and determine the second product between the second load switching threshold and the second hysteresis ratio; If, within a preset time period, the demand load rate exceeds the sum of the second load switching threshold and the second product, the second mode will be switched to the third mode.

[0016] In an optional implementation, the first mapping relationship is obtained in the following way: The second electronic expansion valve is closed. Multiple first sampling openings are set within the effective opening range of the first electronic expansion valve. For any one of the first sampling openings, the following processing is performed: Collect the first outlet temperature and first outlet pressure of the coil in the air handling unit, and find the first refrigerant temperature corresponding to the first outlet temperature and first outlet pressure of the coil; Subtract the first temperature of the refrigerant from the first outlet temperature of the coil to obtain the first superheat, and record the operating condition of the air handling unit corresponding to the first sampling opening. Obtain the current first flow rate of the refrigerant and establish a first mapping relationship between the first sampling opening degree, the first superheat degree, and the first flow rate of the refrigerant; The first mapping relationship corresponding to each first sampling opening is fitted to obtain the first mapping relationship.

[0017] In an optional implementation, the second mapping relationship is obtained in the following way: The first electronic expansion valve is closed. Multiple second sampling openings are set within the effective opening range of the second electronic expansion valve. For any second sampling opening, the following processing is performed: Collect the second outlet temperature and second outlet pressure of the coil in the air handling unit, and find the second refrigerant temperature corresponding to the second outlet temperature and second outlet pressure of the coil. Subtract the second temperature of the refrigerant from the second outlet temperature of the coil to obtain the second superheat, and record the operating condition of the air handling unit corresponding to the second sampling opening. Obtain the current second refrigerant flow rate and establish a second mapping relationship between the second sampling opening degree, the second superheat degree, and the second refrigerant flow rate; The second mapping relationship is obtained by fitting the second mapping relationship corresponding to each second sampling opening.

[0018] Secondly, this application provides an electronic expansion valve assembly control device, wherein the electronic expansion valve assembly includes at least a first electronic expansion valve and a second electronic expansion valve arranged in parallel, the orifice diameters of the first electronic expansion valve and the second electronic expansion valve being different, and the device comprising: The load factor determination module is used to determine the required load factor of the air handling unit; The interval acquisition module is used to acquire the load rate interval in which the demand load rate falls; The mode determination module is used to determine the operating mode of the electronic expansion valve assembly based on the load rate range. An opening control module is used to control the first opening degree of the first electronic expansion valve and / or the second opening degree of the second electronic expansion valve according to the operating mode.

[0019] Thirdly, an air conditioner is also provided, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus. Memory, used to store computer programs; When the processor executes a program stored in the memory, it implements the electronic expansion valve group control method described in any of the first aspects above.

[0020] Fourthly, a storage medium is also provided, wherein the storage medium stores instructions that, when executed on a computer, cause the computer to perform any of the electronic expansion valve group control methods described in the first aspect above.

[0021] Fifthly, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to execute the electronic expansion valve assembly control method described in any of the first aspects above.

[0022] Compared with the prior art, the above-mentioned technical solution provided in this application has the following advantages: The electronic expansion valve group control method provided in this application includes at least a first electronic expansion valve and a second electronic expansion valve arranged in parallel. The diameters of the first and second electronic expansion valves are different. By determining the demand load rate of the air handling unit and obtaining the load rate range in which the demand load rate is located, the working mode of the electronic expansion valve group is determined according to the load rate range. According to the working mode, the first opening degree of the first electronic expansion valve and / or the second opening degree of the second electronic expansion valve are controlled. In this way, by using first and second electronic expansion valves of different diameters connected in parallel to form a valve group, and matching the corresponding working mode and controlling the valve opening degree according to the demand load rate range of the air handling unit, the refrigerant flow can be accurately adjusted across the entire load range. This effectively solves the problems of poor control accuracy of small valve opening under low load and easy noise generation under small valve opening control under low load, while meeting the demand for high load and large flow, and improving the system's adjustment stability and operational comfort. Attached Figure Description

[0023] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0026] Figure 1 This is a schematic diagram of the structure of an electronic expansion valve assembly control system provided in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a multi-unit air conditioning system provided in an embodiment of this application; Figure 3 A schematic diagram illustrating the implementation process of an electronic expansion valve assembly control method provided in this application embodiment; Figure 4 A schematic diagram illustrating the implementation process of another electronic expansion valve assembly control method provided in this application embodiment; Figure 5 A schematic diagram illustrating the implementation process of a method for determining refrigerant demand flow rate provided in an embodiment of this application; Figure 6 A schematic diagram illustrating the implementation process of another electronic expansion valve assembly control method provided in this application embodiment; Figure 7 A schematic diagram illustrating the implementation process of another electronic expansion valve assembly control method provided in this application embodiment; Figure 8 This is a schematic diagram of the structure of an electronic expansion valve assembly control device provided in an embodiment of this application; Figure 9 This is a schematic diagram of the structure of an air conditioner provided in an embodiment of this application. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0029] To address the issues of poor valve control accuracy and noise generation under low load conditions in existing multi-split air conditioning systems, this application provides an electronic expansion valve group control method, device, air conditioner (energy-saving type), and storage medium. The electronic expansion valve group includes at least a first electronic expansion valve and a second electronic expansion valve connected in parallel. The first and second electronic expansion valves have different diameters. By determining the demand load rate of the air handling unit and obtaining the load rate range within which the demand load rate falls, the operating mode of the electronic expansion valve group is determined based on the load rate range. Based on the operating mode, the first opening degree of the first electronic expansion valve and / or the second opening degree of the second electronic expansion valve are controlled. By using first and second electronic expansion valves of different diameters connected in parallel to form a valve group, and matching the corresponding operating mode and valve opening degree according to the demand load rate range of the air handling unit, precise regulation of refrigerant flow can be achieved across the entire load range, while simultaneously meeting high load and high flow rate requirements, thus improving system regulation stability and operational comfort.

[0030] To facilitate understanding of the electronic expansion valve assembly control method of this application, an embodiment of this application provides a structural schematic diagram of an electronic expansion valve assembly control system, as shown below. Figure 1 The diagram illustrates the specific arrangement of a variable-diameter parallel electronic expansion valve assembly in an air handling unit. For example... Figure 1 As shown, the electronic expansion valve assembly control system 10 includes a control box component 11 and an electronic expansion valve assembly 12. The electronic expansion valve assembly 12 integrates a first electronic expansion valve 12-1 and a second electronic expansion valve 12-2. The control box component 11 controls the first electronic expansion valve 12-1 and the second electronic expansion valve 12-2 inside the electronic expansion valve assembly 12 to achieve precise regulation of the refrigerant flow rate.

[0031] The control box component 11 mentioned above integrates a control motherboard. This control motherboard receives the target superheat command from the multi-split main controller and the feedback signal from the temperature / pressure sensor installed on the coil of the air handling unit. It independently calculates and drives the precise opening of the two electronic expansion valves. By controlling the electronic expansion valve group 12, it achieves fine adjustment of the refrigerant flow.

[0032] The aforementioned electronic expansion valve assembly 12 integrates a first electronic expansion valve 12-1 and a second electronic expansion valve 12-2, which are connected in parallel and can be installed in a valve box. The first electronic expansion valve 12-1 is a small-diameter electronic expansion valve with a relatively small rated flow rate (e.g., matching 20%–40% of the total design capacity of the air handling unit), mainly used for precise throttling under low-load conditions. The second electronic expansion valve 12-2 is a large-diameter electronic expansion valve with a relatively large rated flow rate (e.g., matching 60%–80% of the total design capacity), used for main throttling under medium- to high-load conditions or working in conjunction with the first electronic expansion valve. To ensure that the electronic expansion valve assembly 12 can operate within its optimal opening range across the entire load range, the first electronic expansion valve 12-1 and the second electronic expansion valve 12-2 are designed with different diameters.

[0033] The above Figure 1 The electronic expansion valve assembly control system 10 shown is often used in conjunction with air handling units. Figure 2 A schematic diagram of a multi-split air conditioning system is provided, showing the structure of the electronic expansion valve group control system and the air handling unit combined into a multi-split air conditioning system. The multi-split air conditioning system 15 includes a control box component 11, an electronic expansion valve group 12, an outdoor unit 13, and an air handling unit 14.

[0034] The outdoor unit 13 may include core components such as a compressor and a condenser, which are responsible for providing refrigerant circulation power for the entire multi-split system 15 and adjusting the operating frequency of the compressor and the refrigerant flow rate according to the load requirements of each indoor unit.

[0035] The aforementioned air handling unit 14 is a terminal device of a multi-split system, which can be used for fresh air treatment or large space temperature regulation in places such as shopping malls and office buildings. It is equipped with heat exchange coils and fans, and achieves cooling or heating of the air by exchanging heat with the refrigerant flowing through it.

[0036] In the above Figure 1 , Figure 2 Based on the structure shown, Figure 3This is a schematic diagram illustrating the implementation flow of an electronic expansion valve group control method provided in an embodiment of this application. The method operates within a control mainboard integrated inside the control box component 11, and is used to dynamically control the first electronic expansion valve 12-1 and the second electronic expansion valve 12-2. The electronic expansion valve group includes at least a first electronic expansion valve and a second electronic expansion valve arranged in parallel. The diameters of the first and second electronic expansion valves are different, and the method specifically includes the following steps: S301, determine the demand load rate of the air handling unit and obtain the load rate range in which the demand load rate falls.

[0037] In the embodiments of this application, the demand load rate (e.g., Q%) of the air handling unit can be determined, and the load rate range in which the demand load rate falls can be obtained. The demand load rate refers to the percentage of the current required cooling or heating capacity of the air handling unit relative to its total design capacity, used to characterize the current load level of the multi-split system. The demand load rate can be determined by... Figure 1 The control board inside the control box component 11 calculates the load rate range in real time. The load rate range refers to several pre-divided continuous load ranges used to define different operating modes. For example, the load rate range can be divided into a low load range Q%≤θ. L-M (0, 20%), medium load range θ L-M <Q%≤θ M-H (20%, 80%) and Q%>θ M-H High load range (80%, 100%). Determine the load range in which the demand load rate falls from the low load range, medium load range, and high load range based on the demand load rate.

[0038] S302, determine the operating mode of the electronic expansion valve assembly based on the load rate range.

[0039] In this embodiment, the operating mode of the electronic expansion valve assembly can be determined based on the load rate range. The operating mode refers to the control strategy adopted by the electronic expansion valve assembly under different load conditions, such as opening only the first electronic expansion valve, opening only the second electronic expansion valve, or opening both the first and second electronic expansion valves simultaneously. This embodiment does not limit the specific operating mode.

[0040] S303, according to the working mode, controls the first opening degree of the first electronic expansion valve and / or the second opening degree of the second electronic expansion valve.

[0041] In this embodiment, the first opening degree of the first electronic expansion valve and / or the second opening degree of the second electronic expansion valve can be controlled according to the working mode. The first opening degree and the second opening degree refer to the valve opening command values ​​sent by the control motherboard to the first electronic expansion valve and the second electronic expansion valve, respectively. For example, 100% indicates that the first electronic expansion valve and the second electronic expansion valve are opened to the maximum extent.

[0042] Based on the above description of the technical solutions provided in the embodiments of this application, the demand load rate of the air handling unit is determined, and the load rate range in which the demand load rate is located is obtained; according to the load rate range, the working mode of the electronic expansion valve group is determined; according to the working mode, the first opening degree of the first electronic expansion valve and / or the second opening degree of the second electronic expansion valve are controlled.

[0043] By using electronic expansion valves of different diameters in parallel to form a valve group, and matching the corresponding working mode according to the load range of the air handling unit, only the small-diameter electronic expansion valve is used under low load conditions, while the large-diameter electronic expansion valve or the two valves work together as needed under medium and high load conditions. This ensures that both types of valves operate within the optimal linear opening range of, for example, 40% to 70% under both low and medium and high load conditions. This optimizes the throttling effect, reduces operating noise, and avoids the problems of poor control accuracy and noise caused by maintaining a very small opening under low load conditions with single EXV and dual EXV schemes. At the same time, it meets the high load and high flow requirements, and improves the system's regulation stability and operating comfort.

[0044] Based on this, such as Figure 4 The diagram shown illustrates the implementation flow of another electronic expansion valve group control method provided in this application. The electronic expansion valve group includes at least a first electronic expansion valve and a second electronic expansion valve arranged in parallel. The diameters of the first electronic expansion valve and the second electronic expansion valve are different. Figure 4 exist Figure 3 Based on this, the paper details how to determine the demand load rate of the air handling unit and how to determine the operating mode of the electronic expansion valve assembly according to the load rate range. Specifically, this may include the following steps: S401, determine the refrigerant flow requirement of the air handling unit and obtain the rated cooling capacity of the air handling unit.

[0045] In this embodiment, the refrigerant demand flow rate of the air handling unit can be determined, and the rated cooling capacity of the air handling unit can be obtained. The refrigerant demand flow rate refers to the refrigerant flow rate required to pass through the heat exchange coils of the air handling unit to meet its current load, reflecting the actual demand for cooling (or heating) under the current operating conditions. It can be indirectly determined through heat balance calculations on the air side. The rated cooling capacity refers to the maximum cooling capacity that the air handling unit can provide under design conditions (such as standard air volume and standard inlet air parameters), which can be calibrated by the equipment manufacturer at the time of product delivery and pre-stored. Figure 1 In the control main board of control box component 11, the rated cooling capacity is used as a reference value to convert the refrigerant demand flow rate into a dimensionless demand load rate.

[0046] To determine the refrigerant flow requirement of an air handling unit, please refer to the following: Figure 5 The method shown. (As illustrated) Figure 5 The diagram shown illustrates the implementation flow of a method for determining refrigerant demand flow rate according to an embodiment of this application, which may specifically include the following steps: S501, obtain the current air volume in the air handling unit and determine the density of the air at the coil inlet in the air handling unit.

[0047] In this embodiment, the current airflow in the air handling unit can be obtained, and the density of the air at the coil inlet can be determined. The current airflow refers to the actual volumetric flow rate of air delivered by the fan in the air handling unit during current operation. This can be derived from the fan speed versus airflow characteristic curve, or measured in real-time by a wind speed sensor installed in the duct. The current airflow reflects the amount of air flowing through the coils of the air handling unit. The density of the air at the coil inlet refers to the mass-to-volume ratio of the air entering the heat exchange coil at the inlet. The density of the air at the coil inlet is related to the air temperature and humidity. The density of the air at the coil inlet is used to convert the volumetric flow rate into the mass flow rate to ensure the accuracy of subsequent energy calculations.

[0048] Specifically, determining the density of the air at the coil inlet of an air handling unit can include acquiring the temperature and humidity at the coil inlet and determining the density based on these parameters. Specifically, determining the density of the air at the coil inlet can be done by using the thermodynamic properties of moist air, combined with the collected temperature and humidity parameters, and calculating it in real time using the moist air state equation. Alternatively, it can be done by querying a pre-stored moist air property parameter table covering the normal operating temperature and humidity range of the air handling unit in the control board, and then interpolating to determine the density of the air at the coil inlet. The moist air property parameter table is a digital parameter table calibrated based on standard atmospheric pressure, containing a one-to-one correspondence between different dry-bulb temperatures, relative humidity, and moist air densities. The moist air state equation is a dedicated equation for calculating moist air density adapted to HVAC operating conditions and can be corrected according to the local actual atmospheric pressure.

[0049] S502, determine the first specific enthalpy value of the air inlet to the coil in the air handling unit, and the second specific enthalpy value of the air outlet to the coil.

[0050] In this embodiment, a first specific enthalpy value of the air at the coil inlet and a second specific enthalpy value of the air at the coil outlet of the air handling unit can be determined. The first specific enthalpy value refers to the total heat contained per unit mass of air at the coil inlet, including sensible heat and latent heat. It reflects the energy state of the air before it enters the heat exchanger. The second specific enthalpy value refers to the total heat contained per unit mass of air at the coil outlet, reflecting the energy state of the air after it leaves the heat exchanger.

[0051] Specifically, determining the first specific enthalpy value of the air at the coil inlet of an air handling unit can include obtaining the first dry-bulb temperature and the first wet-bulb temperature of the air at the coil inlet of the air handling unit; and determining the first specific enthalpy value of the air at the coil inlet of the air handling unit based on the first dry-bulb temperature and the first wet-bulb temperature. The first dry-bulb temperature can be the actual temperature of the air at the coil inlet measured with a common thermometer, used to reflect the sensible heat of the air. The first wet-bulb temperature can be the temperature of the air at the coil inlet measured with a wet-bulb thermometer under adiabatic saturation conditions, used to comprehensively reflect the temperature and humidity of the air.

[0052] Specifically, the first specific enthalpy value of the air inlet to the coil in the air handling unit is determined based on the first dry-bulb temperature and the first wet-bulb temperature. This can be calculated from the dry-bulb and wet-bulb temperatures using an enthalpy-humidity chart or empirical formula. For example, the first dry-bulb and wet-bulb temperatures can be substituted into the ASHRAE wet air enthalpy calculation formula to obtain the first specific enthalpy value.

[0053] Specifically, determining the second specific enthalpy value of the air at the coil outlet of an air handling unit can include obtaining the second dry-bulb temperature and the second wet-bulb temperature of the air at the coil outlet of the air handling unit; and determining the second specific enthalpy value of the air at the coil outlet of the air handling unit based on the second dry-bulb temperature and the second wet-bulb temperature. The second dry-bulb temperature refers to the actual temperature of the air at the coil outlet measured with a common thermometer, used to reflect the sensible heat change of the air after heat exchange. The second wet-bulb temperature refers to the temperature of the air at the coil outlet measured with a wet-bulb thermometer under adiabatic saturation conditions, used to reflect the overall temperature and humidity state of the air after heat exchange.

[0054] Specifically, the second specific enthalpy value of the air at the coil outlet of the air handling unit is determined based on the second dry-bulb temperature and the second wet-bulb temperature. This can be achieved by substituting the second dry-bulb temperature and the second wet-bulb temperature into the calculation using an enthalpy-humidity chart or empirical formula.

[0055] S503 determines the refrigerant flow requirement of the air handling unit based on the current air volume, density, first specific enthalpy value, and second specific enthalpy value.

[0056] In this embodiment of the application, the refrigerant flow rate requirement of the air handling unit is determined based on the current air volume, density, first specific enthalpy value, and second specific enthalpy value.

[0057] Determining the refrigerant flow rate requirement of an air handling unit based on the current air volume, density, first specific enthalpy value, and second specific enthalpy value can specifically include: inputting the current air volume, density, first specific enthalpy value, and second specific enthalpy value into the refrigerant flow rate requirement calculation formula to obtain the refrigerant flow rate requirement of the air handling unit.

[0058] The formulas for calculating refrigerant demand flow rate include: ; in, V represents the refrigerant flow rate requirement, and V represents the current air volume. For density, The first specific enthalpy value, This is the second specific enthalpy value.

[0059] S402 defines the demand load rate of an air handling unit as the ratio between the refrigerant demand flow rate and the rated cooling capacity.

[0060] In this embodiment, the ratio between the refrigerant demand flow rate and the rated cooling capacity can be determined as the demand load rate of the air handling unit. For example, if the refrigerant demand flow rate is 0.3 kg / s and the refrigerant flow rate corresponding to the rated cooling capacity is 1 kg / s, then the demand load rate is 30%.

[0061] S403, obtain the load factor range in which the demand load factor is located.

[0062] In this embodiment of the application, this step is similar to step S301 above, and will not be described in detail here.

[0063] S404 determines the operating mode of the electronic expansion valve assembly based on the load rate range.

[0064] In this embodiment, the operating mode of the electronic expansion valve assembly can be determined based on the load rate range. Specifically, the diameter of the first electronic expansion valve in the electronic expansion valve assembly is smaller than the diameter of the second electronic expansion valve.

[0065] Determining the operating mode of the electronic expansion valve assembly based on the load rate range can specifically include the following steps: Step 41: When the load rate range is the first load rate range, the first mode is determined as the working mode of the electronic expansion valve group; wherein, in the first mode, the first electronic expansion valve is working and the second electronic expansion valve is closed.

[0066] In this embodiment, when the load rate range is a first load rate range, the first mode is determined as the operating mode of the electronic expansion valve assembly. In this first mode, the first electronic expansion valve operates, and the second electronic expansion valve is closed. The first load rate range can be understood as a low load range; for example, the first load rate range corresponds to a low load range (0, 20%). If the required load rate is in the low load range, the first mode is determined as the operating mode of the electronic expansion valve assembly. The low load range corresponds to a low load and a small required refrigerant flow rate. Therefore, the first mode can be a small valve fine control mode. In this mode, only the small-diameter first electronic expansion valve is opened, and the large-diameter second electronic expansion valve is closed. Because the first electronic expansion valve has a small diameter, it can maintain a large opening (e.g., 40%–70%) at low flow rates, thereby effectively solving the problems of poor control accuracy and high throttling noise under low load conditions.

[0067] Step 42: When the load rate range is the second load rate range, the second mode is determined as the working mode of the electronic expansion valve group; wherein, in the second mode, the first electronic expansion valve is closed and the second electronic expansion valve is open.

[0068] In this embodiment, when the load rate range is the second load rate range, the second mode is determined as the operating mode of the electronic expansion valve assembly. In this second mode, the first electronic expansion valve is closed, and the second electronic expansion valve is open. The second load rate range can be understood as a medium load range; for example, the second load rate range corresponds to a medium load range of (20%, 80%). If the demand load rate is in the medium load range, the second mode is determined as the operating mode of the electronic expansion valve assembly. This medium load range corresponds to a moderate load and a moderate required refrigerant flow rate. The second mode can be understood as a large valve-dominated control mode. In this mode, only the large-diameter second electronic expansion valve is opened, and the small-diameter first electronic expansion valve is closed. The second electronic expansion valve operates at an intermediate opening of 30%–60% within this load range, exhibiting good linearity, stable control, and high throttling efficiency.

[0069] Step 43: When the load rate range is the third load rate range, the third mode is determined as the working mode of the electronic expansion valve group; wherein, in the third mode, the first electronic expansion valve and the second electronic expansion valve work together.

[0070] In this embodiment, when the load rate range is the third load rate range, the third mode is defined as the operating mode of the electronic expansion valve assembly; in the third mode, the first electronic expansion valve and the second electronic expansion valve work together. The third load rate range can be understood as a high load range, for example, the third load rate range corresponds to a high load range (80%, 100%). This high load range corresponds to a working condition with a high load and a large required refrigerant flow. The third mode can be understood as a dual-valve collaborative control mode. In this mode, the first electronic expansion valve and the second electronic expansion valve open simultaneously and work together. By adopting a "coarse adjustment + fine adjustment" control strategy, the large-diameter second electronic expansion valve is used as the main regulating valve, undertaking most of the flow regulation tasks; the small-diameter first electronic expansion valve is used as the fine adjustment compensation valve, and precise compensation is performed based on the difference between the total required flow and the actual flow of the second electronic expansion valve, which can achieve stable regulation of large flow under high load and ensure control accuracy.

[0071] Furthermore, after determining the operating mode of the electronic expansion valve assembly, the operating mode can be switched according to the demand load rate. Specifically, this can include: obtaining a first load switching threshold corresponding to the first mode, and determining a first product between the first load switching threshold and a first hysteresis ratio; if the demand load rate exceeds the sum of the first load switching threshold and the first product within a preset time period, switching the first mode to the second mode; or, obtaining a second load switching threshold corresponding to the second mode, and determining a second product between the second load switching threshold and a second hysteresis ratio; if the demand load rate exceeds the sum of the second load switching threshold and the second product within a preset time period, switching the second mode to the third mode.

[0072] The first load switching threshold can be understood as the low-to-medium load switching point, which is the benchmark value for deciding to switch from the first mode to the second mode.

[0073] The first hysteresis ratio is a preset small increment (such as 4% load) used to build a switching hysteresis range to prevent frequent mode switching due to small load fluctuations near the switching point.

[0074] The preset time period refers to a continuous monitoring time window (e.g., 30 seconds) used to confirm that load changes are a stable trend rather than instantaneous fluctuations. Switching is only performed when the demand load rate continuously exceeds the sum of the first load switching threshold and the first product within this time period, ensuring the reliability of the switching decision.

[0075] The second load switching threshold can be understood as the medium-to-high load switching point, which is the benchmark value for deciding to switch from the second mode to the third mode.

[0076] The second hysteresis ratio is the hysteresis range (e.g., 5% load) used for medium-to-high mode switching to prevent frequent mode switching.

[0077] When the demand load rate exceeds the sum of the second load switching threshold and the second product for a preset period of time, the control motherboard gradually opens the first electronic expansion valve while the second electronic expansion valve is kept in adjustment, and dynamically allocates the fine-tuning opening of the first electronic expansion valve according to the flow difference, so as to achieve a seamless transition from the second mode to the third mode.

[0078] S405, depending on the operating mode, controls the first opening degree of the first electronic expansion valve and / or the second opening degree of the second electronic expansion valve.

[0079] In this embodiment of the application, this step is similar to step S103 above, and will not be described in detail here.

[0080] Based on this, such as Figure 6 The diagram shown illustrates the implementation flow of another electronic expansion valve group control method provided in this application. The electronic expansion valve group includes at least a first electronic expansion valve and a second electronic expansion valve arranged in parallel. The diameters of the first electronic expansion valve and the second electronic expansion valve are different. Figure 6 exist Figure 3 , Figure 4 Based on this, a detailed description is provided on how to control the first opening degree of the first electronic expansion valve and / or the second opening degree of the second electronic expansion valve according to the operating mode. This may include the following steps: S601, determine the refrigerant flow requirement of the air handling unit and obtain the rated cooling capacity of the air handling unit.

[0081] In this embodiment of the application, this step is similar to step S401 above, and will not be described in detail here.

[0082] S602 defines the demand load rate of an air handling unit as the ratio between the refrigerant demand flow rate and the rated cooling capacity.

[0083] In this embodiment of the application, this step is similar to step S402 above, and will not be described in detail here.

[0084] S603, obtain the load factor range in which the demand load factor is located.

[0085] In this embodiment of the application, this step is similar to step S301 above, and will not be described in detail here.

[0086] S604 determines the operating mode of the electronic expansion valve assembly based on the load rate range.

[0087] In this embodiment of the application, this step is similar to step S302 above, and will not be described in detail here.

[0088] S605, determine the total refrigerant flow rate based on the refrigerant flow rate requirement.

[0089] In this embodiment, the total refrigerant flow rate can be determined based on the required refrigerant flow rate. Specifically, the enthalpy difference between the refrigerant inlet and outlet of the evaporator can be obtained, and the total refrigerant flow rate can be obtained by dividing the required refrigerant flow rate by the enthalpy difference. The enthalpy difference between the refrigerant inlet and outlet of the evaporator refers to the difference in enthalpy between the refrigerant at the evaporator inlet and outlet (superheated gas), reflecting the heat absorbed by a unit mass of refrigerant in the evaporator. This enthalpy difference can be obtained by consulting a property table using the refrigerant's state parameters (pressure, temperature) or by real-time calculation using sensors.

[0090] S606, when the operating mode is the first mode, controls the first opening degree of the first electronic expansion valve according to the total refrigerant demand flow.

[0091] In this embodiment of the application, when the working mode is the first mode, the first opening degree of the first electronic expansion valve can be controlled according to the total refrigerant demand flow rate.

[0092] Controlling the first opening degree of the first electronic expansion valve based on the total refrigerant demand flow rate may specifically include the following steps: Step 61: Obtain the set target superheat and the first mapping relationship corresponding to the first electronic expansion valve. The first mapping relationship records the mapping relationship between the opening degree and the flow rate and superheat.

[0093] In this embodiment, a target superheat and a first mapping relationship corresponding to the first electronic expansion valve are obtained. The first mapping relationship records the mapping relationship between the opening degree and the flow rate and superheat. The target superheat can be a control target value issued by the main controller of the multi-split system, referring to the expected value of the refrigerant gas superheat at the evaporator outlet (i.e., the difference between the outlet temperature and the saturation temperature at the corresponding pressure), used to ensure efficient and stable operation of the evaporator and prevent liquid slugging. The first mapping relationship is a table established in advance through experiments or simulations, describing the relationship between the flow rate and superheat corresponding to different opening degrees of the first electronic expansion valve. This table records the mapping relationship between the opening degree (e.g., 0% to 100%) and the refrigerant flow rate and superheat.

[0094] Step 62: Based on the target superheat and total refrigerant demand flow rate, query the first mapping relationship to obtain the first target opening degree.

[0095] In this embodiment of the application, the first target opening degree can be obtained by querying the first mapping relationship based on the target superheat and the total refrigerant demand flow rate.

[0096] The first mapping relationship can be obtained in the following way: Close the second electronic expansion valve. Set multiple first sampling openings (e.g., one sampling point every 5%) within the effective opening range of the first electronic expansion valve (e.g., from the minimum stable opening to the maximum opening). For any first sampling opening, perform the following processing: collect the first outlet temperature and first outlet pressure of the coil in the air handling unit, and find the first refrigerant temperature corresponding to the first outlet temperature and first outlet pressure of the coil; subtract the first refrigerant temperature from the first outlet temperature of the coil to obtain the first superheat, and record the operating conditions of the air handling unit (e.g., air volume, air intake parameters, etc.) corresponding to the first sampling opening; obtain the current first refrigerant flow rate, and establish a first mapping relationship between the first sampling opening, the first superheat, and the first refrigerant flow rate; fit the first mapping relationship corresponding to each first sampling opening to obtain the first mapping relationship.

[0097] The first outlet temperature refers to the temperature sensor reading on the evaporator outlet pipe, and the first outlet pressure refers to the pressure sensor reading on the outlet pipe. The first refrigerant temperature refers to the saturation temperature (evaporation temperature) of the refrigerant at the first outlet pressure.

[0098] Step 63: Adjust the first opening degree of the first electronic expansion valve to the first target opening degree.

[0099] In this embodiment, the first opening degree of the first electronic expansion valve can be adjusted to the first target opening degree.

[0100] S607, when operating in the second mode, controls the second opening degree of the second electronic expansion valve according to the total refrigerant demand flow.

[0101] In this embodiment of the application, when the working mode is the second mode, the second opening degree of the second electronic expansion valve can be controlled according to the total refrigerant demand flow rate.

[0102] Controlling the second opening degree of the second electronic expansion valve based on the total refrigerant demand flow rate may specifically include the following steps: Step 71: Obtain the set target superheat and the second mapping relationship corresponding to the second electronic expansion valve. The second mapping relationship records the mapping relationship between the opening degree and the flow rate and superheat.

[0103] In this embodiment, a target superheat and a second mapping relationship corresponding to the second electronic expansion valve can be obtained. The second mapping relationship records the mapping relationship between the opening degree and the flow rate and superheat. The second mapping relationship describes the relationship between the opening degree of the second electronic expansion valve and the flow rate and superheat.

[0104] Step 72: Based on the target superheat and total refrigerant demand flow rate, query the second mapping relationship to obtain the second target opening degree.

[0105] In this embodiment of the application, the second target opening degree can be obtained by querying the second mapping relationship based on the target superheat and the total refrigerant demand flow rate.

[0106] The second mapping relationship can be obtained as follows: Close the first electronic expansion valve, and set multiple second sampling openings (e.g., one sampling point every 10%) within the effective opening range of the second electronic expansion valve (e.g., from the minimum stable opening to the maximum opening). For any second sampling opening, perform the following processing: Collect the second outlet temperature and second outlet pressure of the coil in the air handling unit, and find the refrigerant second temperature corresponding to the second outlet temperature and second outlet pressure; Subtract the refrigerant second temperature from the second outlet temperature of the coil to obtain the second superheat, and record the operating condition of the air handling unit corresponding to the second sampling opening; Obtain the current refrigerant second flow rate, and establish a second mapping relationship between the second sampling opening, the second superheat, and the refrigerant second flow rate; Fit the second mapping relationship corresponding to each second sampling opening to obtain the second mapping relationship.

[0107] The second outlet temperature refers to the temperature sensor reading on the evaporator outlet pipe, and the second outlet pressure refers to the pressure sensor reading on the outlet pipe. The second refrigerant temperature refers to the saturation temperature (evaporation temperature) of the refrigerant at the second outlet pressure.

[0108] Step 73: Adjust the second opening degree of the second electronic expansion valve to the second target opening degree.

[0109] In this embodiment, the second opening degree of the second electronic expansion valve can be adjusted to the second target opening degree.

[0110] S608, in the third operating mode, controls the first opening degree of the first electronic expansion valve and the second opening degree of the second electronic expansion valve according to the total refrigerant demand flow rate.

[0111] In this embodiment of the application, when the working mode is the third mode, the first opening degree of the first electronic expansion valve and the second opening degree of the second electronic expansion valve can be controlled according to the total refrigerant demand flow rate.

[0112] Controlling the first opening degree of the first electronic expansion valve and the second opening degree of the second electronic expansion valve based on the total refrigerant demand flow rate can specifically include the following steps: Step 81: Obtain the distribution ratio of the second electronic expansion valve, multiply the total refrigerant demand flow rate by the distribution ratio to obtain the main refrigerant distribution flow rate.

[0113] In this embodiment, the allocation ratio of the second electronic expansion valve is obtained, and the total refrigerant demand flow rate is multiplied by the allocation ratio to obtain the main refrigerant share flow rate. The allocation ratio is a preset or dynamically calculated parameter, used to represent the proportion of the total flow rate that the second electronic expansion valve should handle in the second mode, such as 80%. Multiplying this ratio by the total refrigerant demand flow rate allows the second electronic expansion valve to operate within its optimal linear range.

[0114] Step 82: Obtain the set target superheat and the second mapping relationship corresponding to the second electronic expansion valve. The second mapping relationship records the mapping relationship between the opening degree and the flow rate and superheat.

[0115] In this embodiment, a target superheat and a second mapping relationship corresponding to the second electronic expansion valve are obtained. This second mapping relationship records the mapping relationship between the valve opening degree and the flow rate and superheat. The second mapping relationship can be a table established beforehand through experiments or simulations, describing the relationship between the refrigerant flow rate and superheat corresponding to different opening degrees of the second electronic expansion valve. This table records the mapping relationship between the opening degree (e.g., 0%–100%) and the refrigerant flow rate and superheat.

[0116] Step 83: Based on the target superheat and the main refrigerant flow rate, query the second mapping relationship to obtain the third target opening degree.

[0117] In this embodiment, based on the target superheat and the main refrigerant flow rate, a second mapping relationship is consulted to obtain the third target opening degree. The third target opening degree refers to the target opening degree value that the second electronic expansion valve should be adjusted to. The control board uses the target superheat and the main refrigerant flow rate as inputs to find the opening degree value in the second mapping relationship that best meets the target superheat and has the closest flow rate.

[0118] Step 84: Adjust the second opening degree of the second electronic expansion valve to the third target opening degree.

[0119] In this embodiment, the second opening degree of the second electronic expansion valve is adjusted to the third target opening degree.

[0120] Step 85: Subtract the main refrigerant flow rate from the total refrigerant demand flow rate to obtain the auxiliary refrigerant flow rate.

[0121] In this embodiment, the refrigerant auxiliary flow rate is obtained by subtracting the refrigerant main flow rate from the total refrigerant demand flow rate. The refrigerant auxiliary flow rate can be understood as the remaining flow rate that needs to be compensated by the first electronic expansion valve (small valve).

[0122] Step 86: Obtain the first mapping relationship corresponding to the first electronic expansion valve. The first mapping relationship records the mapping relationship between the opening degree and the flow rate and superheat.

[0123] In this embodiment of the application, a first mapping relationship corresponding to the first electronic expansion valve is obtained, and the mapping relationship between the opening degree and the flow rate and superheat is recorded in the first mapping relationship.

[0124] Step 87: Based on the target superheat and refrigerant auxiliary flow rate, query the first mapping relationship to obtain the fourth target opening degree.

[0125] In this embodiment of the application, the fourth target opening degree is obtained by querying the first mapping relationship based on the target superheat and the refrigerant auxiliary flow rate.

[0126] Step 88: Adjust the first opening degree of the first electronic expansion valve to the fourth target opening degree.

[0127] In this embodiment, the first opening degree of the first electronic expansion valve can be adjusted to a fourth target opening degree. The fourth target opening degree refers to the target opening degree value that the first electronic expansion valve should be adjusted to. The control board uses the target superheat and refrigerant auxiliary flow rate as inputs to find the opening degree value in the first mapping relationship that best meets the target superheat and has the closest flow rate.

[0128] Furthermore, the electronic expansion valve assembly control method provided in this application is illustrated with specific examples in the embodiments of this application: Figure 7 This is a schematic diagram illustrating the implementation process of another electronic expansion valve assembly control method provided in this application embodiment. Figure 7 The electronic expansion valve assembly is a variable-bore parallel electronic expansion valve assembly. This assembly is installed in a dedicated valve box and connects to the air handling unit through a unified interface. It includes the following components: A small-bore electronic expansion valve: its rated flow rate is relatively small, for example, to match 20%-40% of the total design capacity of the air handling unit. This valve plays a major throttling role under low load conditions.

[0129] A large-diameter electronic expansion valve: its rated flow rate is relatively large, for example, to match 60%-80% of the total design capacity of the air handling unit. This valve plays a major throttling role under medium load and works with smaller valves to handle high loads.

[0130] The electronic expansion valve assembly can be controlled by a control board. The control board independently calculates and drives the precise opening of the two electronic expansion valves by receiving target superheat commands from the multi-split unit's main controller and feedback signals from temperature / pressure sensors installed on the air handling unit coils.

[0131] Another electronic expansion valve assembly control method provided in this application embodiment may specifically include the following steps: Step 1: Initialize system parameters by loading the mapping table and threshold parameters.

[0132] During the system commissioning phase, system initialization is performed, loading the mapping table and threshold parameters. Specifically, based on the air handling unit coil size and design operating conditions, mapping tables for the opening degree-flow rate-superheat characteristics are established for both the small valve stand-alone mode and the large valve stand-alone mode. Two key load switching thresholds are also defined.

[0133] This can be achieved by establishing a mapping table between opening degree, flow rate, and overheating characteristics through testing. The general process is as follows: Tests are conducted under stable operating conditions (i.e., after parameters such as compressor frequency, fan speed, inlet dry and wet bulb temperatures, and condensing pressure have stabilized). One valve is measured at a time; for example, the small valve is closed when measuring the large valve (and vice versa). The coil outlet temperature Te and pressure are measured using a high-precision sensor. The refrigerant temperature Ts and pressure under saturation can be obtained by referring to the refrigerant property table using the measured temperature and pressure. The superheat SH = Te - Ts. The refrigerant flow rate of the multi-split system can be obtained using a high-precision flow meter.

[0134] Taking a small valve as an example, a series of sampling points are set within the effective valve opening range (e.g., 10%-100%), with a certain opening step size (e.g., 10%). Samples are taken at every interval, and the multi-split system must run stably for a certain period of time (e.g., 15 minutes) before the data is considered valid. In the sensitive range of small valve opening, the sampling step size can be appropriately reduced (e.g., sampling every 5% opening). Each sampling records the key parameters such as compressor frequency, fan speed, inlet dry and wet bulb temperature, condensing pressure, superheat, and refrigerant flow rate, which can be summarized in Table 1 below.

[0135] Table 1

[0136] The two key load switching thresholds mentioned above are: ① Low-to-medium load switching point: This is the threshold for switching from small valve mode to large valve mode. It is usually set at the load rate of the multi-split system when the small valve opening reaches the upper limit of its optimal control range (such as 40%-70% opening).

[0137] ② Medium-high load switching point: This is the threshold for switching from the large valve mode to the dual valve coordinated mode. It is usually set at the load rate of the multi-split system when the large valve opening reaches the upper limit of its optimal control range (such as 30%-60% opening).

[0138] Step 2: Real-time load assessment and mode decision The controller calculates the demand load rate of the air handling unit in real time. This value can be estimated by combining multiple parameters such as target superheat, indoor and outdoor temperature difference, and fan speed, and compared with a preset threshold (i.e., load switching threshold). ① If the demand load rate is less than or equal to the low-to-medium load switching point, then enter the "small valve fine control mode".

[0139] ② If the low-to-medium load switching point < demand load rate ≤ medium-to-high load switching point, then enter the "large valve-dominated control mode".

[0140] ③ If the demand load rate is greater than the medium-high load switching point, then enter the "dual valve coordinated control mode".

[0141] Step 3: Multi-mode precise control execution Small valve fine control mode: Closes the large-diameter electronic expansion valve. The controller only adjusts the opening of the small-diameter electronic expansion valve to precisely throttle the small flow. Since the load demand and valve opening are well matched at this time, the valve opening is in an optimal range, the control accuracy is high, and the valve opening is relatively large (e.g., 40%-70%), the throttling noise will be significantly improved.

[0142] Large valve dominant control mode: Closes the small-diameter electronic expansion valve. The controller switches to regulating the large-diameter electronic expansion valve. At this time, the system load is moderate, and the large valve operates in its good linearity intermediate opening range (such as 30%-60%), resulting in stable control and high throttling efficiency.

[0143] Dual-valve coordinated control mode: The controller uses a large-diameter electronic expansion valve as the main regulating valve, undertaking most of the flow regulation tasks; simultaneously, a small-diameter electronic expansion valve serves as a fine-tuning compensation valve. Its control logic is as follows: ① Calculate the basic opening degree of a large valve based on the total demand flow.

[0144] ② Compare the total required flow rate with the estimated flow rate provided by the large valve at the current opening degree, and the difference is the flow rate fine-tuning amount.

[0145] ③ Convert this flow adjustment amount into the opening command of the small valve. Because the small valve has a small diameter, the control accuracy will be higher at low flow rates. This adjustment can achieve smooth flow replenishment or reduction.

[0146] Through this "coarse adjustment + fine adjustment" mechanism, the system can achieve a smooth adjustment process with no or low oscillation of the flow curve even under high load fluctuations, and the overall control accuracy is better than that of a single valve or two valves of the same diameter.

[0147] Step 4: Execute a smooth transition algorithm to linearly and gradually change the valve opening. To avoid system fluctuations caused by frequent mode switching or sudden changes in traffic near the switching point, a smooth transition algorithm based on hysteresis control and gradual traffic changes can be used.

[0148] Taking the switch from small valve mode to large valve mode as an example: when the load rises and reaches the low-to-medium load switching point, it does not act immediately. When the load continuously exceeds (low-to-medium load switching point + ΔH) (ΔH is the hysteresis load range, such as 4% load), the switch begins. The switching process is as follows: within t seconds, the small valve is linearly closed from its current opening to 0, while the large valve is linearly opened from 0 to an initial opening estimated based on the current total flow demand. Afterward, the controller immediately takes over and adjusts the opening of the large valve. This process ensures a smooth flow transition and minimizes fluctuations in system overheating.

[0149] Corresponding to the above method embodiments, this application also provides an electronic expansion valve group control device. The electronic expansion valve group includes at least a first electronic expansion valve and a second electronic expansion valve arranged in parallel. The diameters of the first electronic expansion valve and the second electronic expansion valve are different, such as... Figure 8 As shown, the device may include: a load rate determination module 801, an interval acquisition module 802, a mode determination module 803, and an opening degree control module 804.

[0150] The load factor determination module 801 is used to determine the demand load factor of the air handling unit. The interval acquisition module 802 is used to acquire the load rate interval in which the demand load rate is located. The mode determination module 803 is used to determine the operating mode of the electronic expansion valve assembly based on the load rate range. The opening control module 804 is used to control the first opening degree of the first electronic expansion valve and / or the second opening degree of the second electronic expansion valve according to the working mode.

[0151] This application also provides an air conditioner (an energy-saving air conditioner), such as... Figure 9 As shown, it includes a processor 901, a communication interface 902, a memory 903, and a communication bus 904, wherein the processor 901, the communication interface 902, and the memory 903 communicate with each other through the communication bus 904. Memory 903 is used to store computer programs; When processor 901 executes a program stored in memory 903, it performs the following steps: The electronic expansion valve assembly includes at least a first electronic expansion valve and a second electronic expansion valve arranged in parallel. The diameters of the first electronic expansion valve and the second electronic expansion valve are different. The demand load rate of the air handling unit is determined, and the load rate range in which the demand load rate falls is obtained. Based on the load rate range, the operating mode of the electronic expansion valve assembly is determined. Based on the operating mode, the first opening degree of the first electronic expansion valve and / or the second opening degree of the second electronic expansion valve are controlled.

[0152] The communication bus mentioned above for air conditioning can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus can be divided into address bus, data bus, control bus, etc. For ease of illustration, only one thick line is used to represent it in the diagram, but this does not mean that there is only one bus or one type of bus.

[0153] The communication interface is used for communication between the air conditioner and other devices.

[0154] The memory may include random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0155] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0156] In another embodiment provided in this application, a storage medium is also provided, which stores instructions that, when run on a computer, cause the computer to execute any of the electronic expansion valve group control methods described in the above embodiments.

[0157] In another embodiment provided in this application, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to execute any of the electronic expansion valve group control methods described in the above embodiments.

[0158] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a storage medium or transmitted from one storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state drive), etc.

[0159] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0160] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0161] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application are included within the scope of protection of this application.

Claims

1. A method for controlling an electronic expansion valve assembly, characterized in that, The electronic expansion valve assembly includes at least a first electronic expansion valve and a second electronic expansion valve arranged in parallel, wherein the orifice diameters of the first electronic expansion valve and the second electronic expansion valve are different, and the method includes: Determine the demand load rate of the air handling unit and obtain the load rate range in which the demand load rate falls; The operating mode of the electronic expansion valve assembly is determined based on the load rate range. According to the operating mode, control the first opening degree of the first electronic expansion valve and / or the second opening degree of the second electronic expansion valve.

2. The method according to claim 1, characterized in that, Determining the demand load rate of the air handling unit includes: Determine the refrigerant flow requirement of the air handling unit and obtain the rated cooling capacity of the air handling unit; The ratio between the required refrigerant flow rate and the rated cooling capacity is determined as the demand load rate of the air handling unit.

3. The method according to claim 2, characterized in that, Determining the refrigerant flow requirement of the air handling unit includes: Obtain the current air volume in the air handling unit and determine the density of the air at the coil inlet in the air handling unit; Determine the first specific enthalpy value of the air at the coil inlet and the second specific enthalpy value of the air at the coil outlet in the air handling unit; The refrigerant flow requirement of the air handling unit is determined based on the current air volume, the density, the first specific enthalpy value, and the second specific enthalpy value.

4. The method according to claim 3, characterized in that, Determining the density of the air at the coil inlet of the air handling unit includes: The temperature and humidity at the coil inlet of the air handling unit are obtained, and the density of the air at the coil inlet of the air handling unit is determined based on the temperature and humidity. Determining the first specific enthalpy value of the air inlet to the coil and the second specific enthalpy value of the air outlet to the coil in the air handling unit includes: The first dry-bulb temperature and the first wet-bulb temperature of the air at the coil inlet of the air handling unit are obtained. The first specific enthalpy value of the air inlet to the coil in the air handling unit is determined based on the first dry-bulb temperature and the first wet-bulb temperature. Obtain the second dry-bulb temperature and the second wet-bulb temperature of the air at the coil outlet of the air handling unit; The second specific enthalpy value of the air at the coil outlet of the air handling unit is determined based on the second dry-bulb temperature and the second wet-bulb temperature.

5. The method according to claim 3, characterized in that, Determining the refrigerant flow requirement of the air handling unit based on the current air volume, the density, the first specific enthalpy value, and the second specific enthalpy value includes: Input the current air volume, the density, the first specific enthalpy value, and the second specific enthalpy value into the refrigerant demand flow calculation formula to obtain the refrigerant demand flow of the air handling unit; The formula for calculating the required refrigerant flow rate includes: ； The The refrigerant required flow rate is V, where V is the current air volume. For the density, the For the first specific enthalpy value, the This is the second specific enthalpy value.

6. The method according to claim 1, characterized in that, The diameter of the first electronic expansion valve is smaller than the diameter of the second electronic expansion valve. Determining the operating mode of the electronic expansion valve assembly based on the load rate range includes: When the load rate range is the first load rate range, the first mode is determined as the working mode of the electronic expansion valve assembly; In the first mode, the first electronic expansion valve is operational, and the second electronic expansion valve is closed. When the load rate range is the second load rate range, the second mode is determined as the operating mode of the electronic expansion valve assembly; In the second mode, the first electronic expansion valve is closed and the second electronic expansion valve is open. When the load rate range is the third load rate range, the third mode is determined as the operating mode of the electronic expansion valve assembly; In the third mode, the first electronic expansion valve and the second electronic expansion valve work together.

7. The method according to claim 2, characterized in that, The step of controlling the first opening degree of the first electronic expansion valve and / or the second opening degree of the second electronic expansion valve according to the operating mode includes: Determine the total refrigerant flow rate based on the refrigerant flow rate requirement; When the operating mode is the first mode, the first opening degree of the first electronic expansion valve is controlled according to the total refrigerant demand flow rate; When the operating mode is the second mode, the second opening degree of the second electronic expansion valve is controlled according to the total refrigerant demand flow rate; When the operating mode is the third mode, the first opening degree of the first electronic expansion valve and the second opening degree of the second electronic expansion valve are controlled according to the total refrigerant demand flow rate.

8. The method according to claim 7, characterized in that, The step of determining the total refrigerant demand flow rate based on the refrigerant demand flow rate includes: Obtain the enthalpy difference of the refrigerant at the inlet and outlet of the evaporator, and divide the required refrigerant flow rate by the enthalpy difference to obtain the total required refrigerant flow rate.

9. The method according to claim 7, characterized in that, The step of controlling the first opening degree of the first electronic expansion valve according to the total refrigerant demand flow rate includes: Obtain the set target superheat and the first mapping relationship corresponding to the first electronic expansion valve. The first mapping relationship records the mapping relationship between the opening degree and the flow rate and superheat. Based on the target superheat and the total refrigerant flow rate, the first target opening degree is obtained by querying the first mapping relationship; Adjust the first opening degree of the first electronic expansion valve to the first target opening degree.

10. The method according to claim 7, characterized in that, The step of controlling the second opening degree of the second electronic expansion valve according to the total refrigerant demand flow rate includes: Obtain the set target superheat and the second mapping relationship corresponding to the second electronic expansion valve. The second mapping relationship records the mapping relationship between the opening degree and the flow rate and superheat. Based on the target superheat and the total refrigerant flow rate, the second target opening degree is obtained by querying the second mapping relationship. Adjust the second opening degree of the second electronic expansion valve to the second target opening degree.

11. The method according to claim 7, characterized in that, The step of controlling the first opening degree of the first electronic expansion valve and the second opening degree of the second electronic expansion valve according to the total refrigerant demand flow rate includes: Obtain the distribution ratio of the second electronic expansion valve, multiply the total refrigerant demand flow rate by the distribution ratio, and obtain the main refrigerant distribution flow rate; Obtain the set target superheat and the second mapping relationship corresponding to the second electronic expansion valve. The second mapping relationship records the mapping relationship between the opening degree and the flow rate and superheat. Based on the target superheat and the main refrigerant flow rate, the second mapping relationship is queried to obtain the third target opening degree; Adjust the second opening degree of the second electronic expansion valve to the third target opening degree; Subtracting the main refrigerant flow rate from the total refrigerant demand flow rate yields the auxiliary refrigerant flow rate. Obtain the first mapping relationship corresponding to the first electronic expansion valve, and record the mapping relationship between opening degree and flow rate and superheat in the first mapping relationship; Based on the target superheat and the refrigerant auxiliary flow rate, the first mapping relationship is queried to obtain the fourth target opening degree; The first opening degree of the first electronic expansion valve is adjusted to the fourth target opening degree.

12. The method according to claim 6, characterized in that, After determining the operating mode of the electronic expansion valve assembly, the method further includes: Obtain the first load switching threshold corresponding to the first mode, and determine the first product between the first load switching threshold and the first hysteresis ratio; If the demand load rate exceeds the sum of the first load switching threshold and the first product within a preset time period, the first mode will be switched to the second mode. or, Obtain the second load switching threshold corresponding to the second mode, and determine the second product between the second load switching threshold and the second hysteresis ratio; If, within a preset time period, the demand load rate exceeds the sum of the second load switching threshold and the second product, the second mode will be switched to the third mode.

13. The method according to claim 9, characterized in that, The first mapping relationship is obtained in the following way: The second electronic expansion valve is closed. Multiple first sampling openings are set within the effective opening range of the first electronic expansion valve. For any one of the first sampling openings, the following processing is performed: Collect the first outlet temperature and first outlet pressure of the coil in the air handling unit, and find the first refrigerant temperature corresponding to the first outlet temperature and first outlet pressure of the coil; Subtract the first temperature of the refrigerant from the first outlet temperature of the coil to obtain the first superheat, and record the operating condition of the air handling unit corresponding to the first sampling opening. Obtain the current first flow rate of the refrigerant and establish a first mapping relationship between the first sampling opening degree, the first superheat degree, and the first flow rate of the refrigerant; The first mapping relationship corresponding to each first sampling opening is fitted to obtain the first mapping relationship.

14. The method according to claim 10, characterized in that, The second mapping relationship is obtained in the following way: The first electronic expansion valve is closed. Multiple second sampling openings are set within the effective opening range of the second electronic expansion valve. For any second sampling opening, the following processing is performed: Collect the second outlet temperature and second outlet pressure of the coil in the air handling unit, and find the second refrigerant temperature corresponding to the second outlet temperature and second outlet pressure of the coil. Subtract the second temperature of the refrigerant from the second outlet temperature of the coil to obtain the second superheat, and record the operating condition of the air handling unit corresponding to the second sampling opening. Obtain the current second refrigerant flow rate and establish a second mapping relationship between the second sampling opening degree, the second superheat degree, and the second refrigerant flow rate; The second mapping relationship is obtained by fitting the second mapping relationship corresponding to each second sampling opening.

15. An electronic expansion valve assembly control device, characterized in that, The electronic expansion valve assembly includes at least a first electronic expansion valve and a second electronic expansion valve arranged in parallel, wherein the orifice diameters of the first electronic expansion valve and the second electronic expansion valve are different, and the device includes: The load factor determination module is used to determine the required load factor of the air handling unit; The interval acquisition module is used to acquire the load rate interval in which the demand load rate falls; The mode determination module is used to determine the operating mode of the electronic expansion valve assembly based on the load rate range. An opening control module is used to control the first opening degree of the first electronic expansion valve and / or the second opening degree of the second electronic expansion valve according to the operating mode.

16. An air conditioner, characterized in that, It includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; Memory, used to store computer programs; A processor, when executing a program stored in memory, implements the method described in any one of claims 1-14.

17. A storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1-14.

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