Air conditioning unit system, control method of electronic expansion valve in air conditioning unit system, computer readable storage medium and computer equipment

Abstract

The invention relates to an air conditioning unit system, a control method of an electronic expansion valve in the air conditioning unit system, a computer readable storage medium and computer equipment, and the air conditioning unit system comprises a compressor, a condenser, the electronic expansion valve, an evaporator and a controller; an exhaust port of the compressor is connected with an inlet of the condenser through a first pipeline; an outlet of the condenser is connected with an inlet of the electronic expansion valve through a second pipeline; an outlet of the electronic expansion valve is connected with an inlet of the evaporator through a third pipeline; an outlet of the evaporator is connected with an air suction port of the compressor through a fourth pipeline; a low-pressure sensor is arranged on the fourth pipeline; a high-pressure sensor is arranged on the first pipeline; a upstream pressure sensor and a upstream temperature sensor are arranged on the second pipeline; the third pipeline is provided with a downstream pressure sensor; the controller is electrically connected with the low-pressure sensor, the high-pressure sensor, the upstream pressure sensor, the downstream pressure sensor, the upstream temperature sensor and the electronic expansion valve.

Description

Technical Field

[0001] This invention relates to the field of air conditioning equipment and refrigeration control system technology, and more specifically, to air conditioning unit systems, control methods for electronic expansion valves in air conditioning unit systems, computer-readable storage media, and computer equipment. Background Technology

[0002] Traditional air conditioning systems typically consist of a compressor, condenser, throttling device (such as a thermostatic expansion valve or capillary tube), evaporator, and connecting piping, forming a complete refrigeration cycle. Their control systems rely heavily on relatively macroscopic adjustments such as compressor start / stop and fan speed regulation, resulting in a rather coarse understanding and control of the refrigerant's state within the system. Especially under varying operating conditions or significant load fluctuations, traditional throttling devices exhibit slow response and low precision, making it difficult to ensure the system consistently operates at optimal energy efficiency. While some systems have adopted electronic expansion valves as an improvement, their control strategies often rely solely on the evaporator's superheat, calculated by detecting the evaporator outlet temperature and pressure. This single-point control method has inherent limitations. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an air conditioning unit system, a control method for an electronic expansion valve in the air conditioning unit system, a computer-readable storage medium, and a computer device, in view of the problems existing in the prior art.

[0004] The technical solution adopted by this invention to solve its technical problem is as follows: An air conditioning unit system is constructed, including a compressor, a condenser, an electronic expansion valve, an evaporator, and a controller; the exhaust port of the compressor is connected to the inlet of the condenser via a first pipe; the outlet of the condenser is connected to the inlet of the electronic expansion valve via a second pipe; the outlet of the electronic expansion valve is connected to the inlet of the evaporator via a third pipe; the outlet of the evaporator is connected to the suction port of the compressor via a fourth pipe; a low-pressure sensor is installed on the fourth pipe; a high-pressure sensor is installed on the first pipe; a pre-valve pressure sensor and a pre-valve temperature sensor are installed on the second pipe; and a post-valve pressure sensor is installed on the third pipe. The controller is electrically connected to the low-pressure sensor, the high-pressure sensor, the inlet pressure sensor, the outlet pressure sensor, the inlet temperature sensor, and the electronic expansion valve.

[0005] This application provides a control method for an electronic expansion valve in an air conditioning unit system, applied to the aforementioned air conditioning unit system, comprising the following steps: Step S1: Based on the signals from the low-pressure sensor and the high-pressure sensor, and the operating status of the compressor, obtain a first parameter characterizing the current refrigerant output capacity of the compressor; Step S2: Based on the signals from the inlet pressure sensor, outlet pressure sensor, and inlet temperature sensor, obtain a second parameter characterizing the refrigerant flow state through the electronic expansion valve. Step S3: Determine the target flow rate setting value of the electronic expansion valve based on the first parameter; Step S4: Based on the target flow rate setting value and the second parameter, determine and output the drive signal for controlling the opening of the electronic expansion valve.

[0006] In one embodiment, step S1 includes: step S11, determining the current suction pressure and current discharge pressure of the compressor based on the signals from the low-pressure sensor and the high-pressure sensor, respectively; step S12, determining the corresponding current evaporation temperature Te based on the current suction pressure, and determining the corresponding current condensation temperature Tc based on the current discharge pressure; step S13, obtaining the current operating speed N of the compressor; step S14, calculating the theoretical refrigerant circulation flow rate of the compressor based on the current evaporation temperature Te, the current condensation temperature Tc, and the current operating speed N, and using the theoretical refrigerant circulation flow rate as the first parameter characterizing its current refrigerant output capacity.

[0007] In one embodiment, step S14 includes: determining a first set of model coefficients based on the current operating speed N, the first set of model coefficients containing multiple coefficients related to compressor flow rate; substituting the current evaporation temperature Te and the current condensation temperature Tc into a preset compressor flow rate calculation formula, and calculating based on the coefficients in the first set of model coefficients to obtain the theoretical refrigerant circulation flow rate M1 of the compressor; The preset compressor flow rate calculation formula is as follows: M1 = C1 + C2 Te+C3 Tc+C4 Te 2 +C5 Te Tc+C6 Tc 2 +C7 Te³+C8 Te² Tc+C9 Te Tc²+C10 Tc³; Wherein, C1 to C10 are the coefficients in the first set of model coefficients.

[0008] In one embodiment, step S2 includes: determining the current inlet pressure P_in and the current outlet pressure P_out of the electronic expansion valve based on the signals from the pre-valve pressure sensor and the post-valve pressure sensor, respectively; and calculating the current operating pressure difference ΔP of the electronic expansion valve, where ΔP = P_in - P_out. Based on the signals from the inlet pressure sensor and the inlet temperature sensor, the current inlet pressure P_in and the current inlet temperature T_in of the electronic expansion valve are determined; based on the current inlet pressure P_in and the current inlet temperature T_in, the current density ρ of the refrigerant at the inlet of the electronic expansion valve is determined; the current operating pressure difference ΔP and the current density ρ are combined as the second parameter characterizing the refrigerant flow state through the electronic expansion valve.

[0009] In one embodiment, step S3 includes: limiting the current refrigerant output capacity of the compressor characterized by the first parameter to generate a target flow rate setting value M2 for the electronic expansion valve; wherein the target flow rate setting value M2 satisfies M2≤M1, and M1 is the theoretical refrigerant circulation flow rate of the compressor.

[0010] In one embodiment, step S4 includes: calculating the target opening degree h by solving a preset valve flow characteristic equation based on the target flow rate setting value M2, the current working pressure difference ΔP, and the current density ρ, combined with the inherent structural parameters of the electronic expansion valve; and generating a drive signal corresponding to the target opening degree h.

[0011] In one embodiment, the inherent structural parameters include the valve needle cone angle β and the valve orifice diameter d; the valve flow characteristic equation is expressed as: in, The flow coefficient is related to the opening degree, h is the opening height of the electronic expansion valve and corresponds to the target opening degree h, β is the valve needle cone angle, d is the valve orifice diameter, ρ is the current density, and ΔP is the current working pressure difference.

[0012] This application also provides a computer-readable storage medium storing a computer program adapted to be loaded and executed by a processor to implement the steps of the control method for the electronic expansion valve as described above.

[0013] This application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor calls and executes the computer program stored in the memory to implement the steps of the electronic expansion valve control method as described above.

[0014] The beneficial effect of this invention is that it integrates multiple pressure and temperature sensors at key nodes of the refrigeration cycle (compressor discharge, suction, expansion valve front and rear, and condenser outlet) to construct a multi-parameter collaborative monitoring and control system. This system enables the controller to acquire key status information in real time, such as high pressure, low pressure, pressure difference across the valve, condenser outlet subcooling, and evaporator superheat. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a schematic diagram of the air conditioning unit system of the present invention; Figure 2 This is a logic flowchart of an embodiment of the electronic expansion valve control method of the present invention. Detailed Implementation

[0016] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the invention are now described in detail with reference to the accompanying drawings. In the following description, specific details such as particular structures and techniques are set forth for illustrative purposes and not for limitation, so as to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known devices, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0017] like Figure 1 As shown, Figure 1 This is a structural diagram of an air conditioning unit system.

[0018] The technical solution adopted by the present invention to solve its technical problem is as follows: an air conditioning unit system is constructed, including a compressor 1, a condenser 2, an electronic expansion valve 3, an evaporator 4, and a controller; the exhaust port of the compressor 1 is connected to the inlet of the condenser 2 through a first pipe 5; the outlet of the condenser 2 is connected to the inlet of the electronic expansion valve 3 through a second pipe 6; the outlet of the electronic expansion valve 3 is connected to the inlet of the evaporator 4 through a third pipe 7; and the outlet of the evaporator 4 is connected to the suction port of the compressor 1 through a fourth pipe 8. A low-pressure sensor 9 is installed on the fourth pipeline 8; a high-pressure sensor 10 is installed on the first pipeline 5; a valve inlet pressure sensor 11 and a valve inlet temperature sensor 12 are installed on the second pipeline 6; and a valve outlet pressure sensor 13 is installed on the third pipeline 7. The controller is electrically connected to the low-pressure sensor 9, the high-pressure sensor 10, the inlet pressure sensor 11, the outlet pressure sensor 13, the inlet temperature sensor 12, and the electronic expansion valve 3.

[0019] It should be noted that by deploying a sensor network at the aforementioned key locations, the controller can acquire a multi-dimensional set of system status information in real time. This includes not only the parameters needed to calculate the evaporator outlet superheat, but also all data used to calculate the condenser outlet subcooling (based on the inlet pressure sensor 11 and inlet temperature sensor 12), the operating pressure difference across the electronic expansion valve (based on the inlet pressure sensor 11 and outlet pressure sensor 13), and the system's high and low pressure differences (based on the high-pressure sensor 10 and low-pressure sensor 9). These multi-dimensional parameters provide the physical basis for the controller to implement an advanced control strategy that combines feedforward and feedback, surpassing traditional single-point feedback, thereby significantly improving the system's dynamic response speed and overall energy efficiency.

[0020] In one embodiment, the second pipeline 6 is also equipped with a dryer filter 14 and a sight glass 15. The dryer filter 14 is used to absorb moisture that may be contained in the refrigerant and filter out solid impurities to ensure the cleanliness and dryness of the refrigerant, prevent ice blockage or dirt blockage in the system, and thus protect precision components such as the electronic expansion valve 3. The sight glass 15 is used to visually observe the physical state of the refrigerant (such as color and bubble condition) to help determine whether the refrigerant charge is appropriate and whether there is insufficient subcooling at the condenser outlet (manifested as the presence of bubbles), providing a direct basis for system commissioning and daily maintenance.

[0021] This application provides a control method for an electronic expansion valve in an air conditioning unit system, applied to the aforementioned air conditioning unit system, comprising the following steps: Step S1: Based on the signals from the low-pressure sensor 9 and the high-pressure sensor 10, and the operating status of the compressor 1, obtain the first parameter characterizing the current refrigerant output capacity of the compressor 1; Step S2: Based on the signals from the inlet pressure sensor 11, the outlet pressure sensor 13, and the inlet temperature sensor 12, obtain a second parameter characterizing the refrigerant flow state through the electronic expansion valve 3. Step S3: Determine the target flow rate setting value of the electronic expansion valve 3 based on the first parameter; Step S4: Based on the target flow rate setting value and the second parameter, determine and output the drive signal used to control the opening degree of the electronic expansion valve 3.

[0022] It should be noted that this invention establishes a feedforward control based on the actual circulating capacity of compressor 1, supplemented by necessary feedback correction. Specifically: steps S1 and S3 together constitute the feedforward control loop, which aims to pre-determine the target flow rate (target flow rate setpoint) that the electronic expansion valve 3 should match based on the actual refrigerant supply capacity (first parameter) of compressor 1 under the current operating conditions. This enables rapid prediction and response to load changes, solving the regulation lag problem caused by waiting for superheat deviation in traditional PID control. Steps S2 and S4 constitute the precise execution and feedback loop. By calculating the second parameter (directly related to differential pressure and density) characterizing the current actual flow state in real time, and combining it with the target flow rate setpoint, the required valve opening is accurately calculated and driven. This composite control architecture of "capacity feedforward + state feedback" is the key to achieving rapid, stable, and efficient system operation.

[0023] In one embodiment, step S1 includes: step S11, determining the current suction pressure and current discharge pressure of compressor 1 based on the signals from low-pressure sensor 9 and high-pressure sensor, respectively; step S12, determining the corresponding current evaporation temperature Te based on the current suction pressure, and determining the corresponding current condensation temperature Tc based on the current discharge pressure; step S13, obtaining the current operating speed N of compressor 1; step S14, calculating the theoretical refrigerant circulation flow rate of compressor 1 based on the current evaporation temperature Te, the current condensation temperature Tc, and the current operating speed N, and using the theoretical refrigerant circulation flow rate as the first parameter characterizing its current refrigerant output capacity.

[0024] It should be noted that this step utilizes a physical model to combine the system's high and low pressure states (reflecting external operating conditions) with the compressor 1 speed (reflecting internal power input), mapping out the instantaneous theoretical displacement of compressor 1. The evaporation temperature Te and condensation temperature Tc are obtained by referring to a refrigerant property parameter library (such as CoolProp) based on the corresponding saturation pressure or by calculation. This ensures the accuracy of the temperature parameters and overcomes the potential delays and installation location effects that may exist with direct temperature measurement.

[0025] In one embodiment, step S14 includes: The first set of model coefficients is determined based on the current operating speed N. The first set of model coefficients contains multiple coefficients related to the flow rate of compressor 1. Substitute the current evaporation temperature Te and the current condensation temperature Tc into the preset compressor 1 flow calculation formula, and calculate according to the coefficients in the first set of model coefficients to obtain the theoretical refrigerant circulation flow rate M1 of compressor 1; The preset formula for calculating the flow rate of compressor 1 is: M1 = C1 + C2 Te+C3 Tc+C4 Te 2 +C5 Te Tc+C6 Tc 2 +C7 Te³+C8 Te² Tc+C9 Te Tc²+C10 Tc³; C1 to C10 are the coefficients in the first set of model coefficients.

[0026] It should be noted that the polynomial form of the compressor 1 flow rate calculation formula is a high-precision empirical model obtained through extensive experimental testing of a specific model of compressor 1 under different operating conditions (variable speed, evaporation temperature, and condensation temperature) using data fitting methods (such as multivariate nonlinear regression). For the variable frequency compressor 1, different speeds N correspond to different sets of coefficients (C1~C10), which accurately reflects the nonlinear characteristics of compressor 1's performance as a function of speed. This method directly calculates the flow rate through the model, and compared to traditional simplified calculations or volumetric efficiency estimations based on the ideal gas law, it has higher accuracy and adaptability to operating conditions, forming the basis for achieving high-precision feedforward control.

[0027] In one embodiment, step S2 includes: Based on the signals from the upstream pressure sensor 11 and the downstream pressure sensor 13, the current inlet pressure P_in and the current outlet pressure P_out of the electronic expansion valve 3 are determined respectively. The current operating pressure difference ΔP of the electronic expansion valve 3 is calculated, where ΔP = P_in - P_out; Based on the signals from the inlet pressure sensor 11 and the inlet temperature sensor 12, the current inlet pressure P_in and the current inlet temperature T_in of the electronic expansion valve 3 are determined. Based on the current inlet pressure P_in and the current inlet temperature T_in, determine the current density ρ of the refrigerant at the inlet of electronic expansion valve 3; The current operating pressure difference ΔP and the current density ρ are combined as a second parameter characterizing the refrigerant flow state through the electronic expansion valve 3.

[0028] It should be noted that the second parameters (ΔP and ρ) are two key instantaneous state variables that determine the refrigerant mass flow rate through the electronic expansion valve 3. According to the valve flow equation, the mass flow rate is related to... They are directly proportional. Real-time acquisition of these two parameters provides accurate current operating conditions for calculating the required opening degree based on the target flow rate setpoint in subsequent steps. The inlet density ρ is also calculated from the refrigerant property parameter library based on the measured pressure P_in and temperature T_in, ensuring the accuracy of the property parameters.

[0029] In one embodiment, step S3 includes: The current refrigerant output capacity of compressor 1, characterized by the first parameter, is limited to generate the target flow setpoint M2 for electronic expansion valve 3. The target flow rate setpoint M2 satisfies M2≤M1, where M1 is the theoretical refrigerant circulation flow rate of compressor 1.

[0030] It should be noted that this step is the core principle for ensuring the safety and energy efficiency of this control method. Setting the target flow rate M2 of the electronic expansion valve 3 to no greater than the theoretical refrigerant circulation flow rate M1 of the compressor 1 has the physical meaning of ensuring that the liquid supply to the evaporator does not exceed the maximum "suction" capacity of the compressor 1 under the current operating conditions. This proactively prevents the risk of liquid accumulation in the evaporator and liquid return (liquid carrying) to the compressor 1 due to excessive liquid supply. At the same time, by setting a target value slightly smaller than M1 (for example, multiplying by a safety factor less than 1 or fine-tuning based on the target superheat), conditions can be created to maintain a stable and moderate superheat at the evaporator outlet, thereby optimizing the heat exchange efficiency of the evaporator while ensuring the safety of the compressor 1.

[0031] In one embodiment, step S4 includes: Based on the target flow rate setpoint M2, the current working pressure difference ΔP, and the current density ρ, combined with the inherent structural parameters of the electronic expansion valve 3, the target opening h is calculated by solving the preset valve flow characteristic equation; and a drive signal corresponding to the target opening h is generated.

[0032] It should be noted that this step is a key computational node for realizing the "feedforward-feedback" closed loop of flow control. It combines the "demand flow rate" (M2) obtained from the feedforward stage with the "current resistance status" (ΔP and ρ) monitored by the feedback stage. Through a precise valve mathematical model, it directly calculates the precise valve opening command (h) required to achieve the demand flow rate under the current operating conditions. This method avoids the process of repeatedly trying and integrating to find the appropriate opening degree, as in traditional PID control, thus improving response speed and control accuracy.

[0033] In one embodiment, the inherent structural parameters include the valve needle cone angle β and the valve orifice diameter d; The valve flow characteristic equation is expressed as: in, The flow coefficient is related to the opening degree, h is the opening height of the electronic expansion valve 3 and corresponds to the target opening degree h, β is the valve needle cone angle, d is the valve orifice diameter, ρ is the current density, and ΔP is the current working pressure difference.

[0034] In this step, it should be noted that the equation is based on the general flow characteristic physical model of the electronic expansion valve 3 with a conical valve needle structure. The π in the equation... h sin(β / 2) (dh / 2 The sinβ component precisely describes the geometric relationship between the flow area A and the opening height h. By combining the flow coefficient Cv (usually a function of the opening h), obtained by the manufacturer through calibration experiments and reflecting actual flow characteristics, with this geometric area, the physical property parameters (ρ) under the current operating conditions, and the driving force (ΔP), a high-fidelity valve flow forward / reverse calculation model is constructed. Based on this model, the controller can reversely solve for a unique and accurate target opening h value based on the target flow setpoint M2, the measured ΔP, and ρ.

[0035] like Figure 2 As shown, in a specific embodiment, the process includes the following steps: initialization and system modeling, real-time data acquisition and state calculation, state calculation based on acquired data, feedforward calculation and target setting, control decision and opening degree calculation, execution and closed-loop formation.

[0036] 1. Initialization and system modeling include: Determine the refrigerant type: Select the specific refrigerant used in the system (such as R410A, R32, etc.), which is the basis for all physical property parameter calculations.

[0037] Determine the compressor 1 model: Based on the specific compressor 1 model selected for the unit, a compressor 1-flow mapping table is established through experimental data fitting. This mapping table reflects the theoretical refrigerant circulation flow rate of compressor 1 at different speeds (N), evaporation temperatures (Te), and condensation temperatures (Tc). For variable frequency compressor 1, this mapping table is multi-dimensional, relating speed to operating conditions.

[0038] Determine the structural parameters of the electronic expansion valve 3: Obtain the key structural parameters of the electronic expansion valve 3 used, such as the valve needle cone angle (β) and the valve orifice diameter (d).

[0039] A mapping table for the three opening degrees of an electronic expansion valve and its flow coefficient was established: Based on the valve's structural parameters and manufacturer calibration data, a mapping table for the three opening degrees of an electronic expansion valve and its flow coefficient was established. This table defines the flow coefficient (Cv) of the valve at different opening degrees (h), and is the key to connecting the opening command with the flow capacity. It should be noted that the opening degree can also be calculated by solving the valve's flow characteristic equation.

[0040] 2. Real-time data acquisition and status calculation (feedback input): During system operation, the controller collects the following sensor data in real time: Read the discharge pressure of compressor 1 (via high pressure sensor 10) and the suction pressure of compressor 1 (via low pressure sensor 9).

[0041] Read the current operating speed N of compressor 1 (for variable frequency compressor 1).

[0042] Read the pressure P_in (pre-valve pressure sensor 1111) and temperature T_in (pre-valve temperature sensor 1212) before the electronic expansion valve 3.

[0043] Read the pressure P_out after the electronic expansion valve 3 (after valve pressure sensor 1313).

[0044] 3. Perform state calculations based on collected data: To confirm the evaporation and condensation temperatures Tc / Te by calling the CoolProp property functions: Based on the compressor 1 discharge pressure (corresponding to the condensation pressure) and suction pressure (corresponding to the evaporation pressure), call the CoolProp library to calculate the current condensation temperature Tc and evaporation temperature Te respectively.

[0045] The CoolProp property function is used to confirm the refrigerant density ρ before the valve: Based on the measured pressure P_in and temperature T_in before the electronic expansion valve 3, the CoolProp library is called to calculate the current density ρ of the refrigerant before the valve.

[0046] Read the pressure before and after the electronic expansion valve 3 and calculate the pressure difference ΔP: Based on P_in and P_out, calculate the real-time working pressure difference ΔP of the electronic expansion valve 3 (ΔP=P_in-P_out).

[0047] 4. Feedforward calculation and target setting: Read the compressor 1 speed and calculate the theoretical refrigerant circulation flow rate M1 according to the compressor 1-flow mapping table: Take the current compressor 1 speed N, the calculated Te and Tc as inputs, query or calculate the compressor 1-flow mapping table to obtain the theoretical refrigerant circulation flow rate M1 of compressor 1 under the current operating conditions. This theoretical refrigerant circulation flow rate M1 serves as the flow rate reference for the system requirement.

[0048] 5. Control Decision and Opening Calculation: Based on the principles of ensuring system safety (preventing backflow) and optimizing performance, the target flow setting value M2 of the electronic expansion valve 3 is determined according to M1 (usually M2≤M1).

[0049] The target flow setpoint M2, the real-time calculated inlet density ρ, the real-time differential pressure ΔP, and the structural parameters of the electronic expansion valve 3 are substituted into the valve flow characteristic equation (or model). By determining the opening degree of the electronic expansion valve 3 according to the opening degree-flow coefficient mapping table, the precise target opening degree h required under the current operating conditions (ρ, ΔP) to achieve the target flow setpoint M2 is solved in reverse. This step essentially maps the "flow demand" into an "action command" through the valve's physical model and real-time operating conditions.

[0050] 6. Execution and closed-loop formation: The controller converts the calculated target opening h into a corresponding drive signal (such as the number of pulses) and sends it to the stepper motor of the electronic expansion valve 3.

[0051] Electronic expansion valve 3 adjusts the opening degree to change the refrigerant flow rate.

[0052] Changes in flow rate will gradually affect the state of the entire system, causing changes in parameters such as evaporation pressure, condensation pressure, and temperature.

[0053] The controller enters the next control cycle and returns to step 2 (real-time data acquisition and state calculation). Based on the new system state fed back by the sensors, it performs feedforward calculation and control decisions again, thus forming a continuously running and dynamically adjusted logical closed loop.

[0054] This control closed loop begins with precise modeling (mapping table) of the system's core components (compressor 1, electronic expansion valve 3). During operation, the system state is acquired through a real-time sensor network and converted into key control parameters (Te, Tc, ρ, ΔP) using a property library. Using a feedforward approach, the system flow demand (M1) is predicted based on the compressor 1 model (mapping table), and a safety target (M2) is set. Finally, combining the valve model (mapping table) and real-time operating conditions, the flow target is directly and accurately calculated into valve action commands (h). After the action is executed, the system state changes, sensor data is updated, and the closed loop is thus formed, achieving a rapid and accurate response to system changes.

[0055] This application also provides a computer-readable storage medium storing a computer program adapted to be loaded and executed by a processor to implement the steps of the control method for the electronic expansion valve 3 as described above.

[0056] This application also provides a computer device, including a memory and a processor. The memory stores a computer program, and the processor calls and executes the computer program stored in the memory to implement the steps of the control method for the electronic expansion valve 3 as described above.

[0057] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. An air conditioning unit system, comprising a compressor (1), a condenser (2), an electronic expansion valve (3), an evaporator (4), and a controller; the exhaust port of the compressor (1) is connected to the inlet of the condenser (2) via a first pipe (5); the outlet of the condenser (2) is connected to the inlet of the electronic expansion valve (3) via a second pipe (6); the outlet of the electronic expansion valve (3) is connected to the inlet of the evaporator (4) via a third pipe (7); and the outlet of the evaporator (4) is connected to the suction port of the compressor (1) via a fourth pipe (8). Its features are, A low-pressure sensor (9) is installed on the fourth pipeline (8); a high-pressure sensor (10) is installed on the first pipeline (5); a valve inlet pressure sensor (11) and a valve inlet temperature sensor (12) are installed on the second pipeline (6); and a valve outlet pressure sensor (13) is installed on the third pipeline (7). The controller is electrically connected to the low-pressure sensor (9), the high-pressure sensor (10), the inlet pressure sensor (11), the outlet pressure sensor (13), the inlet temperature sensor (12), and the electronic expansion valve (3).

2. A control method for an electronic expansion valve in an air conditioning unit system, applied to the air conditioning unit system as described in claim 1, characterized in that, Includes the following steps: Step S1: Based on the signals from the low-pressure sensor (9) and the high-pressure sensor (10), and the operating status of the compressor (1), obtain a first parameter characterizing the current refrigerant output capacity of the compressor (1); Step S2: Based on the signals from the inlet pressure sensor (11), outlet pressure sensor (13), and inlet temperature sensor (12), obtain a second parameter characterizing the refrigerant flow state through the electronic expansion valve (3); Step S3: Determine the target flow rate setting value of the electronic expansion valve (3) based on the first parameter; Step S4: Based on the target flow rate setting value and the second parameter, determine and output the drive signal for controlling the opening degree of the electronic expansion valve (3).

3. The control method for the electronic expansion valve in the air conditioning unit system according to claim 2, characterized in that, Step S1 includes: Step S11: Determine the current intake pressure and current exhaust pressure of the compressor (1) based on the signals from the low-pressure sensor (9) and the high-pressure sensor (10); Step S12: Determine the corresponding current evaporation temperature Te based on the current intake pressure, and determine the corresponding current condensation temperature Tc based on the current exhaust pressure; Step S13: Obtain the current operating speed N of the compressor (1); Step S14: Calculate the theoretical refrigerant circulation flow rate of the compressor (1) based on the current evaporation temperature Te, the current condensation temperature Tc, and the current operating speed N, and use the theoretical refrigerant circulation flow rate as the first parameter characterizing its current refrigerant output capacity.

4. The control method for the electronic expansion valve in the air conditioning unit system according to claim 3, characterized in that, Step S14 includes: The first set of model coefficients is determined based on the current operating speed N. The first set of model coefficients contains multiple coefficients related to the flow rate of the compressor (1). Substitute the current evaporation temperature Te and the current condensation temperature Tc into the preset compressor (1) flow calculation formula, and calculate according to the coefficients in the first set of model coefficients to obtain the theoretical refrigerant circulation flow rate M1 of the compressor (1); The preset flow rate calculation formula for the compressor (1) is as follows: M1=C1+C2 Te+C3 Tc+C4 Te 2 +C5 Te Tc+C6 Tc 2 +C7 Te³+C8 Te² Tc+C9 Te Tc²+C10 Tc³; Wherein, C1 to C10 are the coefficients in the first set of model coefficients.

5. The control method for the electronic expansion valve in the air conditioning unit system according to claim 2, characterized in that, Step S2 includes: Based on the signals from the inlet pressure sensor (11) and the outlet pressure sensor (13), the current inlet pressure P_in and the current outlet pressure P_out of the electronic expansion valve (3) are determined respectively. The current working pressure difference ΔP of the electronic expansion valve (3) is calculated, where ΔP = P_in - P_out; Based on the signals from the inlet pressure sensor (11) and the inlet temperature sensor (12), the current inlet pressure P_in and the current inlet temperature T_in of the electronic expansion valve (3) are determined; Based on the current inlet pressure P_in and the current inlet temperature T_in, determine the current density ρ of the refrigerant at the inlet of the electronic expansion valve (3); The current operating pressure difference ΔP and the current density ρ are combined as the second parameter characterizing the refrigerant flow state through the electronic expansion valve (3).

6. The control method for the electronic expansion valve in the air conditioning unit system according to claim 2, characterized in that, Step S3 includes: The current refrigerant output capacity of the compressor (1) characterized by the first parameter is limited to generate the target flow setting value M2 of the electronic expansion valve (3); Wherein, the target flow rate setting value M2 satisfies M2≤M1, where M1 is the theoretical refrigerant circulation flow rate of the compressor (1).

7. The control method for the electronic expansion valve in the air conditioning unit system according to claim 5, characterized in that, Step S4 includes: Based on the target flow rate setting value M2, the current working pressure difference ΔP, and the current density ρ, combined with the inherent structural parameters of the electronic expansion valve (3), the target opening degree h is calculated by solving the preset valve flow characteristic equation; and a drive signal corresponding to the target opening degree h is generated.

8. The control method for the electronic expansion valve in the air conditioning unit system according to claim 7, characterized in that, The inherent structural parameters include the valve needle cone angle β and the valve orifice diameter d; The valve flow characteristic equation is expressed as follows: in, The flow coefficient is related to the opening degree, h is the opening height of the electronic expansion valve (3) and corresponds to the target opening degree h, β is the valve needle cone angle, d is the valve orifice diameter, ρ is the current density, and ΔP is the current working pressure difference.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program adapted to be loaded and executed by a processor to implement the steps of the control method for the electronic expansion valve as described in any one of claims 2-8.

10. A computer device, characterized in that, The device includes a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the control method for the electronic expansion valve as described in any one of claims 2-8 by calling and executing the computer program stored in the memory.

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