An intelligent environmental protection refrigeration control method, system, product and medium

Abstract

An intelligent environmental protection refrigeration control method, system, product and medium, wherein the method comprises: obtaining operating state parameters, refrigerant leakage concentration and recovery state parameters; generating refrigeration power adjustment parameters when the refrigerant leakage concentration is less than a preset safety threshold, and adjusting the speed of a variable frequency compressor and the opening of an electronic expansion valve; when the refrigerant leakage concentration is greater than or equal to the preset safety threshold, controlling the liquid supply valve to be closed and the electronic expansion valve to maintain a preset evacuation opening; generating an evacuation state parameter and determining a target evacuation speed, and controlling the variable frequency compressor to operate at the target evacuation speed; when the low-pressure side pipeline pressure is less than or equal to a preset evacuation threshold, or the variable frequency compressor meets a preset evacuation stop condition, controlling the variable frequency compressor to stop operating and generating a recovery control parameter, and controlling the refrigerant recovery device to recover the refrigerant. The application can improve the emergency control efficiency of the refrigeration device.

Description

Technical Field

[0001] This application relates to the field of refrigeration control technology, specifically to an intelligent and environmentally friendly refrigeration control method, system, product, and medium. Background Technology

[0002] With refrigeration equipment being widely used in various refrigeration scenarios, and with increasingly stringent environmental protection requirements, how to effectively address refrigerant leaks and reduce environmental pollution through intelligent control has become an important research direction in the refrigeration field.

[0003] In existing technologies, the compressor's operating status and the opening of the throttling device are typically adjusted based on parameters such as the temperature of the refrigerated space and the pipeline pressure to match the cooling capacity with the actual load. Simultaneously, to reduce the safety risks and environmental impacts of refrigerant leakage, refrigerant leak detection components are also installed in the refrigeration unit. When the detected refrigerant leakage concentration reaches a preset threshold, the control module usually triggers an alarm and controls the refrigeration unit to enter a fault handling state, such as stopping refrigeration operation, closing relevant valves, or activating the refrigerant recovery device.

[0004] However, when a refrigerant leak occurs, a certain amount of refrigerant usually remains in the refrigeration cycle, and the distribution of refrigerant in different components and pipelines is affected by factors such as system operating conditions, pipeline pressure changes, and valve status. If the fault handling process is based solely on a uniform approach according to the leak concentration, it can easily lead to insufficient matching between the refrigerant recovery process and the actual state within the refrigeration cycle, resulting in inaccurate refrigeration control response under fault conditions and affecting the emergency control efficiency of the refrigeration unit. Summary of the Invention

[0005] This application provides an intelligent and environmentally friendly refrigeration control method, system, product, and medium to solve the technical problem of insufficient matching between the refrigerant recovery process and the actual state within the refrigeration cycle loop, resulting in inaccurate refrigeration control response under fault conditions, thereby improving the emergency control efficiency of refrigeration devices.

[0006] The first aspect of this application provides an intelligent and environmentally friendly refrigeration control method applied to a refrigeration device. The refrigeration device includes a refrigeration cycle loop and a monitoring module, a control module, and a refrigerant recovery device connected to the refrigeration cycle loop. The refrigeration cycle loop includes a variable frequency compressor, a condenser, an electronic expansion valve, a liquid supply valve, an evaporator, a low-pressure side pipeline, and a high-pressure side pipeline. The liquid supply valve is located on the high-pressure side pipeline between the condenser and the electronic expansion valve. The refrigerant recovery device is connected to the high-pressure side pipeline through a recovery branch. The method includes: The monitoring module acquires operating status parameters, refrigerant leakage concentration, and recovery status parameters, including low-pressure side pipeline pressure. When the refrigerant leakage concentration is less than a preset safety threshold, cooling power adjustment parameters are generated based on the operating status parameters, and the speed of the variable frequency compressor and the opening of the electronic expansion valve are adjusted according to the cooling power adjustment parameters. When the refrigerant leakage concentration is greater than or equal to the preset safety threshold, the liquid supply valve is controlled to close, and the electronic expansion valve is controlled to maintain the preset evacuation opening, so that the pipe section between the liquid supply valve and the electronic expansion valve is connected to the low-pressure side pipe through the electronic expansion valve, the evaporator and the low-pressure side pipe, forming an evacuation channel connected to the suction end of the variable frequency compressor. The evacuation status is evaluated based on the operating status parameters to obtain evacuation status parameters. Based on the evacuation status parameters, the target evacuation speed is determined, and the variable frequency compressor is controlled to operate at the target evacuation speed to pressurize the refrigerant in the evacuation channel to the high-pressure side pipeline. When the pressure in the low-pressure side pipeline is less than or equal to the preset evacuation threshold, or when the variable frequency compressor meets the preset evacuation stop condition, the control module controls the variable frequency compressor to stop running, and generates recovery control parameters based on the recovery status parameters. Based on the recovery control parameters, the refrigerant recovery device is controlled to recover the refrigerant in the high-pressure side pipeline through the recovery branch.

[0007] Optionally, the operating status parameters also include the evaporator outlet temperature and the actual refrigerated space temperature. The step of generating refrigeration power adjustment parameters based on these operating status parameters, and adjusting the speed of the variable frequency compressor and the opening of the electronic expansion valve according to these refrigeration power adjustment parameters, specifically includes: Obtain the target cooling temperature, calculate the temperature deviation between the actual cooling space temperature and the target cooling temperature, and determine the target compressor speed based on the temperature deviation. Based on the low-pressure side pipeline pressure and the preset refrigerant pressure-saturation temperature mapping relationship, the evaporation saturation temperature is determined, and the difference between the evaporator outlet temperature and the evaporation saturation temperature is calculated to obtain the actual superheat. Calculate the superheat deviation between the actual superheat and the preset target superheat, and determine the expansion valve feedforward compensation amount based on the target compressor speed; The target expansion valve opening is determined based on the superheat deviation and the expansion valve feedforward compensation, and the target compressor speed and the target expansion valve opening are used as the refrigeration power adjustment parameters. The variable frequency compressor is controlled to operate according to the target compressor speed, and the electronic expansion valve is controlled to adjust its opening according to the target expansion valve opening.

[0008] Optionally, the expansion valve feedforward compensation amount is determined based on the target compressor speed, specifically including: Obtain the current compressor speed and calculate the speed change between the target compressor speed and the current compressor speed; The low-pressure safety margin is determined based on the difference between the low-pressure side pipeline pressure and the preset low-pressure protection threshold, wherein the preset low-pressure protection threshold is greater than the preset evacuation threshold. The current heat load coefficient is determined based on the temperature deviation value. The dynamic feedforward gain coefficient is determined based on the low-pressure safety margin and the current heat load coefficient. When the speed change is greater than zero, the dynamic feedforward gain coefficient is negatively correlated with the low-pressure safety margin and positively correlated with the current heat load coefficient. The product of the speed change and the preset basic feedforward coefficient is determined as the basic opening compensation amount; The initial feedforward compensation amount is obtained by performing gain correction on the basic opening compensation amount based on the dynamic feedforward gain coefficient. The initial feedforward compensation amount is limited according to the preset upper limit and lower limit of the opening compensation to obtain the feedforward compensation amount of the expansion valve.

[0009] Optionally, the operating status parameters also include the high-pressure side pipeline pressure. The step of evaluating the evacuation status based on these operating status parameters to obtain evacuation status parameters, and determining the target evacuation speed based on these evacuation status parameters, specifically includes: The rate of decrease in low-pressure side pipeline pressure and the rate of increase in refrigerant leakage concentration are determined based on the decrease in low-pressure side pipeline pressure within a preset time window and the increase in refrigerant leakage concentration within the preset time window, respectively. The rate of decrease in low-pressure side pressure and the rate of increase in leakage concentration are used as the evacuation state parameters, and the basic evacuation speed is determined based on the rate of increase in leakage concentration, wherein the basic evacuation speed is positively correlated with the rate of increase in leakage concentration. Calculate the rate deviation between the low-pressure side pressure drop rate and the preset target drop rate, and determine the evacuation speed compensation amount based on the rate deviation; The sum of the base evacuation speed and the evacuation speed compensation amount is determined as the initial evacuation speed; The real-time compression ratio is determined based on the pressure in the high-pressure side pipeline and the pressure in the low-pressure side pipeline, and the initial evacuation speed is subjected to safety limiting processing based on the real-time compression ratio to obtain the target evacuation speed.

[0010] Optionally, the initial evacuation speed is subjected to a safety limit based on the real-time compression ratio to obtain the target evacuation speed, specifically including: The real-time compression ratio is compared with a preset compression ratio safety threshold. When the real-time compression ratio is less than or equal to the preset compression ratio safety threshold, the initial evacuation speed is limited based on the preset upper limit and lower limit of the evacuation speed to obtain the target evacuation speed. When the real-time compression ratio is greater than the preset compression ratio safety threshold, a frequency reduction and limiting coefficient is determined based on the over-limit difference between the real-time compression ratio and the preset compression ratio safety threshold. The frequency reduction and limiting coefficient is greater than zero and less than one, and the frequency reduction and limiting coefficient is negatively correlated with the over-limit difference. Based on the frequency reduction and amplitude limiting coefficient, the initial evacuation speed is corrected by frequency reduction to obtain the corrected evacuation speed; The target evacuation speed is obtained by limiting the modified evacuation speed based on the preset upper limit and the preset lower limit of the evacuation speed.

[0011] Optionally, the recovery status parameters include the recovery tank pressure and the remaining capacity of the recovery tank. The step of generating recovery control parameters based on the recovery status parameters, and controlling the refrigerant recovery device to recover refrigerant from the high-pressure side pipeline via the recovery branch based on the recovery control parameters, specifically includes: The recovery pressure difference between the high-pressure side pipeline and the recovery storage tank is determined based on the pressure of the high-pressure side pipeline and the pressure of the recovery storage tank. Based on the high-pressure side pipeline pressure and the preset recovery termination pressure, determine the remaining pressure to be recovered, obtain the current converted temperature of the storage tank, and determine the receiving capacity of the storage tank based on the remaining capacity of the recovery storage tank and the current converted temperature of the storage tank. When the recovery pressure difference is greater than the preset recovery start pressure difference, and the storage tank receiving capacity meets the capacity requirement corresponding to the pressure to be recovered, the recovery control parameters are generated based on the recovery pressure difference, the pressure to be recovered, and the storage tank receiving capacity. The recovery control parameters include recovery device start parameters, target recovery power parameters, and recovery termination pressure parameters. The refrigerant recovery device is started based on the recovery device start parameters, and the refrigerant recovery device is controlled to recover the refrigerant in the high-pressure side pipeline through the recovery branch based on the target recovery power parameters; When the pressure in the high-pressure side pipeline is less than or equal to the pressure value corresponding to the recovery termination pressure parameter, the refrigerant recovery device is controlled to stop recovery.

[0012] Optionally, the recovery control parameters are generated based on the recovery pressure differential, the pressure margin to be recovered, and the receiving margin of the storage tank, specifically including: When the recovery pressure difference is greater than the preset impact pressure difference threshold, the start-up parameters of the recovery device are configured to a preset soft-start mode; When the recovery pressure difference is less than or equal to the preset impact pressure difference threshold, the start-up parameters of the recovery device are configured to a preset direct start-up mode; The basic recovery power parameters are determined based on the pressure margin to be recovered, and the basic recovery power parameters are positively correlated with the pressure margin to be recovered. A power correction coefficient is determined based on the receiving margin of the storage tank, and the power correction coefficient is positively correlated with the receiving margin of the storage tank; The product of the basic recovery power parameter and the power correction coefficient is determined as the target recovery power parameter; The termination pressure compensation amount is determined based on the tank receiving margin, and the termination pressure compensation amount is negatively correlated with the tank receiving margin. The preset recovery termination pressure is superimposed with the termination pressure compensation amount to obtain the recovery termination pressure parameter.

[0013] In a second aspect, embodiments of this application provide an intelligent and environmentally friendly refrigeration control system, which includes: one or more processors and a memory; the memory is coupled to the one or more processors, and the memory is used to store computer program code, which includes computer instructions, and the one or more processors call the computer instructions to cause the intelligent and environmentally friendly refrigeration control system to perform the method described in the first aspect and any possible implementation thereof.

[0014] Thirdly, embodiments of this application provide a computer-readable storage medium including instructions that, when executed on an intelligent environmentally friendly refrigeration control system, cause the intelligent environmentally friendly refrigeration control system to perform the method described in the first aspect and any possible implementation thereof.

[0015] Fourthly, embodiments of this application provide a computer program product containing instructions that, when the computer program product is run on an intelligent environmentally friendly refrigeration control system, cause the intelligent environmentally friendly refrigeration control system to execute the method described in the first aspect and any possible implementation thereof.

[0016] In summary, one or more technical solutions provided in this application have at least the following technical effects or advantages: 1. When the refrigerant leakage concentration is greater than or equal to a preset safety threshold, an evacuation channel is created by controlling the liquid supply valve to close and maintaining the electronic expansion valve at a preset evacuation opening, thus establishing a connection with the suction end of the variable frequency compressor. Subsequently, based on the evacuation status parameters obtained from the evaluation of operating status parameters, the target evacuation speed is determined, and the variable frequency compressor is controlled to operate, dynamically compressing the refrigerant in the evacuation channel to the high-pressure side pipeline, preventing continuous refrigerant leakage on the low-pressure side. When the pressure in the low-pressure side pipeline is less than or equal to the preset evacuation threshold or meets the preset evacuation stop condition, the variable frequency compressor is stopped, and recovery control parameters are generated based on the recovery status parameters to control the refrigerant recovery device to recover the refrigerant in the high-pressure side pipeline. By combining pipeline isolation, dynamic evacuation based on actual conditions, and centralized recovery, the shortcomings of existing technologies, such as insufficient matching between recovery and actual conditions due to standardized handling, are overcome, improving the accuracy of refrigeration control and the efficiency of emergency control under fault conditions.

[0017] 2. Under normal cooling conditions, the target compressor speed is determined by the temperature deviation between the actual cooling space temperature and the target cooling temperature. The superheat deviation is calculated based on the low-pressure side pipeline pressure and the evaporator outlet temperature. Simultaneously, the change in compressor speed between the target and current speeds is calculated. This, combined with the low-pressure safety margin determined by the low-pressure side pipeline pressure and the current heat load coefficient determined by the temperature deviation, determines the dynamic feedforward gain coefficient. This coefficient is used to correct the gain of the base opening compensation amount and, after limiting, to obtain the expansion valve feedforward compensation amount. Finally, the target expansion valve opening is determined by combining the superheat deviation and the expansion valve feedforward compensation amount. This process combines feedforward control of compressor speed changes with superheat feedback control. The feedforward compensation amount can dynamically and adaptively adjust according to the system's heat load status and low-pressure safety margin. This effectively overcomes the lag of single feedback regulation, improves the system's cooling response speed during load fluctuations, and avoids low-pressure protection or operational instability caused by expansion valve overshoot, achieving precise and stable regulation of cooling power.

[0018] 3. When determining the target evacuation speed, the rate of pressure drop on the low-pressure side and the rate of increase in leakage concentration are used as evacuation state parameters. The base evacuation speed is determined based on the rate of increase in leakage concentration to quickly respond to the severity of the leakage. Simultaneously, the evacuation speed compensation amount is determined based on the rate deviation between the rate of pressure drop on the low-pressure side and the preset target rate of drop, resulting in the initial evacuation speed, thus achieving dynamic closed-loop regulation of the evacuation speed. Furthermore, the real-time compression ratio is determined based on the pressure in the high-pressure side pipeline and the low-pressure side pipeline. When the real-time compression ratio exceeds the preset compression ratio safety threshold, a negatively correlated frequency reduction and amplitude limiting coefficient is determined based on the over-limit difference. This coefficient is used to correct the frequency of the initial evacuation speed and apply amplitude limiting to obtain the target evacuation speed. This process not only adaptively adjusts the evacuation speed according to the urgency of the leakage and the progress of evacuation to ensure evacuation efficiency, but also effectively prevents compressor overload or damage caused by a sharp increase in compression ratio in the later stages of evacuation, balancing the high efficiency of emergency evacuation with the operational safety of the compressor.

[0019] 4. During the refrigerant recovery stage, the recovery pressure difference is determined based on the pressure in the high-pressure side pipeline and the pressure in the recovery storage tank. Combined with the remaining pressure to be recovered and the tank receiving capacity determined by the remaining capacity of the recovery storage tank and the current tank temperature, recovery control parameters are generated when the start-up conditions are met. Specifically, the start-up parameters of the recovery device are adaptively configured to a preset soft-start mode or a preset direct-start mode based on the magnitude of the recovery pressure difference. Simultaneously, the target recovery power parameter is obtained by multiplying the basic recovery power parameter, which is positively correlated with the remaining pressure to be recovered, and the power correction coefficient, which is positively correlated with the tank receiving capacity. The termination pressure compensation, which is negatively correlated with the tank receiving capacity, is then added to the preset recovery termination pressure to obtain the recovery termination pressure parameter. This process not only effectively avoids the start-up shock to pipelines and equipment caused by excessive pressure difference in the initial recovery phase, but also dynamically adjusts the recovery power based on the amount to be recovered on the high-pressure side and the actual receiving capacity of the storage tank. Furthermore, it adaptively increases the recovery termination pressure to end the recovery early when the tank capacity is insufficient. Overall, this achieves smooth start-up, efficient operation, and overcharge protection in the recovery process, ensuring the safety and reliability of centralized refrigerant recovery. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the architecture of the refrigeration device applied in the embodiments of this application; Figure 2 This is a flowchart illustrating an intelligent and environmentally friendly refrigeration control method according to an embodiment of this application; Figure 3 This is a flowchart illustrating the process of determining the target evacuation speed in an embodiment of this application; Figure 4 This is a schematic diagram of the structure of an intelligent and environmentally friendly refrigeration control system provided in an embodiment of this application.

[0021] Explanation of reference numerals in the attached drawings: 301, Central Processing Unit; 302, Read-Only Memory; 303, Random Access Memory; 304, Bus; 305, Input / Output Interface; 306, Input Section; 307, Output Section; 308, Storage Section; 309, Communication Section; 310, Driver; 311, Removable Media. Detailed Implementation

[0022] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0023] In the description of the embodiments of this application, the words "for example" or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design that is described as "for example" or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design options. Rather, the use of the words "for example" or "for instance" is intended to present the relevant concepts in a specific manner.

[0024] In the description of the embodiments of this application, the term "multiple" means two or more. For example, multiple systems means two or more systems, and multiple screen terminals means two or more screen terminals. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. The terms "comprising," "including," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0025] Figure 1 A schematic diagram of the refrigeration device in this application is shown. Figure 1 As shown, the refrigeration device mainly includes a refrigeration cycle loop, as well as a monitoring module, a control module, and a refrigerant recovery device connected to the refrigeration cycle loop.

[0026] The refrigeration cycle is used to achieve a phase change cycle of the refrigerant to provide refrigeration capacity. Following the refrigerant flow direction indicated by the solid arrow in the diagram, the refrigeration cycle sequentially includes a variable frequency compressor, a condenser, a liquid supply valve, an electronic expansion valve, and an evaporator. The section of pipe from the discharge end of the variable frequency compressor through the condenser to the inlet of the electronic expansion valve is defined as the high-pressure side pipe; the section of pipe from the evaporator outlet to the suction end of the variable frequency compressor is defined as the low-pressure side pipe. It should be noted that the liquid supply valve is located on the high-pressure side pipe, specifically between the condenser and the electronic expansion valve. Under normal refrigeration conditions, the liquid supply valve is normally open; in emergency situations such as leaks, the liquid supply valve can be controlled to close, thereby cutting off the refrigerant supply from the high-pressure side to the low-pressure side and physically isolating the system piping.

[0027] A refrigerant recovery device is used to centrally recover residual refrigerant in the pipeline when a system leak occurs. The refrigerant recovery device is connected to the high-pressure side pipeline via a recovery branch. Specifically, the connection point of the recovery branch is located on the high-pressure side pipeline between the condenser and the liquid supply valve. Preferably, a recovery valve is also installed on the recovery branch. After the system performs evacuation to accumulate refrigerant in the high-pressure side pipeline upstream of the condenser and liquid supply valve, the refrigerant recovery device can draw the refrigerant from the high-pressure side pipeline into its internal recovery storage tank by opening the recovery valve.

[0028] The monitoring module is used to collect various operational data of the refrigeration unit in real time. For example... Figure 1 As shown by the dashed line (signal / control line), the monitoring module is electrically connected to the following monitoring points: Low-pressure side pressure monitoring point (P): installed on the low-pressure side pipeline, used to collect the low-pressure side pipeline pressure in real time; Refrigerant Leakage Concentration Monitoring Point (L): Located around the refrigeration equipment (especially near components prone to leakage such as evaporators) to collect real-time refrigerant leakage concentration in the environment; Refrigerant recovery status monitoring point (M): Located at the refrigerant recovery device, used to collect recovery status parameters such as the pressure of the recovery tank and the remaining capacity of the recovery tank.

[0029] The control module is the core of the refrigeration unit's control (e.g., a PLC, microcontroller, or dedicated controller). The control module communicates with the monitoring module (in practical applications, they can also be integrated on the same main control board) to acquire various parameters collected by the monitoring module. Simultaneously, the control module's output is electrically connected to the variable frequency compressor, recovery valve, liquid supply valve, electronic expansion valve, and refrigerant recovery device. Based on the acquired operating status parameters, leakage concentration, and recovery status parameters, the control module performs corresponding logical operations and sends control commands to the aforementioned components (such as adjusting the variable frequency compressor speed, adjusting the electronic expansion valve opening, controlling the opening and closing of the liquid supply valve and recovery valve, and starting and stopping the refrigerant recovery device), thereby realizing the intelligent and environmentally friendly refrigeration control method described in this application.

[0030] Figure 2 This is a flowchart illustrating an intelligent and environmentally friendly refrigeration control method in an embodiment of this application.

[0031] Please see Figure 2 This application discloses an intelligent and environmentally friendly refrigeration control method, applied to a refrigeration device. The method includes: S101. Obtain the operating status parameters, refrigerant leakage concentration and recovery status parameters collected by the monitoring module, wherein the operating status parameters include the low-pressure side pipeline pressure; During the operation of the refrigeration unit, the control module needs to have a comprehensive understanding of the system's internal thermodynamic state, the safety status of the external environment, and the standby status of peripheral auxiliary equipment. This provides accurate data support for subsequent routine adjustments to the refrigeration power and emergency evacuation and recovery in the event of a sudden leak. To achieve the aforementioned control objectives, the control module continuously receives multi-dimensional low-level data collected in real time by the monitoring module through various sensors according to a preset sampling period.

[0032] The monitoring module collects refrigerant leakage concentration in real time through gas concentration sensors placed around the evaporator and inside the refrigeration equipment casing. The refrigerant leakage concentration objectively reflects the degree of refrigerant gas accumulation in the external space of the refrigeration cycle loop. The control module determines whether the system is in normal refrigeration operation or a leakage fault condition based on the relationship between the refrigerant leakage concentration and a preset safety threshold. The preset safety threshold is typically set based on the physical combustion characteristics of the refrigerant used and relevant national safety standards (such as the percentage of the lower flammability limit (LFL)). For the slightly flammable R32 refrigerant, the preset safety threshold is usually set between 15% and 25% of the LFL, corresponding to a specific mass concentration of approximately 0.044 kg / m³ to 0.073 kg / m³, ensuring sufficient emergency response time before reaching dangerous concentrations.

[0033] To assess the internal physical state of the refrigeration cycle loop, the monitoring module simultaneously collects multiple operating status parameters. These parameters specifically include low-pressure side piping pressure, high-pressure side piping pressure, evaporator outlet temperature, actual refrigerated space temperature, and current compressor speed. The monitoring module uses a pressure transmitter installed on the suction side of the inverter compressor to obtain the low-pressure side piping pressure and a pressure transmitter installed on the discharge side of the inverter compressor to obtain the high-pressure side piping pressure. Both the low-pressure and high-pressure side pressures reflect the current pressure ratio of the system and the refrigerant charge abundance within the piping. The monitoring module uses a patch or insertion-type temperature sensor to obtain the evaporator outlet temperature, an ambient temperature sensor to obtain the actual refrigerated space temperature, and reads the low-level registers of the inverter compressor driver to obtain the current compressor speed. The actual refrigerated space temperature characterizes the ambient heat load demand; the evaporator outlet temperature, combined with the low-pressure side piping pressure, is used to subsequently calculate the actual superheat of the system; and the current compressor speed serves as the basic reference for subsequent feedforward compensation control.

[0034] Considering the need for safe refrigerant transfer in the event of a leak, the monitoring module also needs to collect the recovery status parameters of the refrigerant recovery device. These parameters specifically include the recovery tank pressure, remaining capacity, and current equivalent temperature of the tank. The monitoring module obtains the recovery tank pressure through a pressure sensor installed at the top of the tank and the remaining capacity through a level gauge or a bottom weighing sensor. To accurately calculate the current equivalent temperature of the tank, the control module incorporates an ambient temperature compensation algorithm based on a one-dimensional steady-state heat conduction model. A specific algorithm formula is: T_eq = T_surf + K_comp * (T_surf - T_env) + C_offset; In the formula, T_eq represents the current converted temperature of the storage tank, T_surf represents the real-time surface temperature of the tank's outer wall collected by a patch-type temperature sensor, and T_env represents the real-time ambient temperature collected by an ambient temperature sensor. Because heat is transferred through the tank wall when there is a temperature difference between the refrigerant temperature inside the tank and the ambient temperature, the outer wall surface temperature is only an intermediate point temperature in the heat dissipation process. Therefore, the algorithm calculates the difference between the outer wall surface temperature and the ambient temperature and multiplies it by the material and environmental compensation coefficient K_comp to inversely derive and compensate for the temperature gradient drop caused by heat penetrating the tank wall. K_comp is set based on the comprehensive ratio of the tank wall thickness, the thermal conductivity of the tank material, and the convective heat transfer coefficient of the outer surface. For common carbon steel or stainless steel recycling tanks, the specific value range of K_comp is calibrated between 0.05 and 0.15. Meanwhile, to eliminate measurement errors caused by the physical installation of the sensor, a sensor contact thermal resistance compensation constant C_offset is introduced into the formula. C_offset is set based on the microscopic gap between the temperature sensor probe and the contact surface of the tank's outer wall, as well as the actual thermal resistance loss of the thermal grease. Under standard installation procedures, its specific value range is set from 0.2℃ to 0.8℃. After the aforementioned comprehensive compensation correction, the final calculated equivalent temperature of the tank closely approximates the true thermodynamic state of the refrigerant inside the tank. The control module, by comprehensively considering the tank pressure, remaining capacity, and current equivalent temperature, can accurately assess whether the refrigerant recovery device currently possesses the physical conditions to safely receive high-pressure refrigerant from the high-pressure side pipeline, preventing tank overpressure explosions or liquid slugging hazards during subsequent recovery processes.

[0035] By synchronously acquiring the aforementioned multi-dimensional parameters, the control module constructs a complete data matrix that includes environmental safety, system operating conditions, and the status of the recycling equipment, enabling the refrigeration device to have the information foundation to transform from single temperature feedback regulation to global state adaptive and collaborative control.

[0036] S102. When the refrigerant leakage concentration is less than a preset safety threshold, generate refrigeration power adjustment parameters according to the operating status parameters, and adjust the speed of the variable frequency compressor and the opening of the electronic expansion valve according to the refrigeration power adjustment parameters respectively. When the refrigerant leakage concentration is less than the preset safety threshold, it indicates that the refrigeration unit is operating in a safe environment and no leakage fault has occurred. At this time, the core task of the control module is to accurately match the cooling capacity according to the environmental heat load demand and maintain the efficient and stable operation of the refrigeration cycle loop. To achieve the aforementioned control objective, the control module needs to comprehensively consider operating status parameters such as the actual refrigerated space temperature, low-pressure side pipeline pressure, and evaporator outlet temperature. By integrating feedforward control of the compressor speed with feedback control of the evaporator superheat, it accurately calculates and generates refrigeration power adjustment parameters. Specifically, this includes the following steps.

[0037] S1021. Obtain the target cooling temperature, calculate the temperature deviation between the actual cooling space temperature and the target cooling temperature, and determine the target compressor speed based on the temperature deviation. Under normal refrigeration conditions, to accurately generate refrigeration power adjustment parameters, the control module calls upon the evaporator outlet temperature and the actual refrigerated space temperature as operating status parameters. The actual refrigerated space temperature directly reflects the current thermodynamic state of the target refrigeration area and is a core indicator for assessing external heat load demand. By comparing the actual refrigerated space temperature with the preset target refrigeration temperature, the control module can macroscopically determine the required refrigeration output of the system, thus providing a basis for adjusting the speed of the variable frequency compressor. The setting of the target refrigeration temperature depends on the specific application scenario; for example, it is typically set to -18℃ to -25℃ in refrigeration and 22℃ to 26℃ in conventional air conditioning. Meanwhile, the evaporator outlet temperature characterizes the state of heat absorption completed by the refrigerant at the evaporator end. In the refrigeration cycle, the refrigerant evaporation saturation temperature can only be calculated based on the low-pressure side pipeline pressure alone; the actual superheat must be calculated accurately in conjunction with the evaporator outlet temperature. The actual superheat is a key physical quantity for measuring whether the refrigerant supply from the electronic expansion valve matches the heat exchange capacity of the evaporator. By combining the actual cooling space temperature and the evaporator outlet temperature, the control module can lay the data foundation for subsequent accurate calculation of the target compressor speed and target expansion valve opening from two dimensions: macro load demand and micro refrigerant flow.

[0038] During normal operation of the refrigeration unit, to ensure precise matching between the system's output cooling capacity and the environmental heat load demand, the control module first executes the calculation logic for the target compressor speed. The control module reads the system's pre-set target cooling temperature, which is set based on the specific application scenario. For example, in a freezing and preservation scenario, it is typically set to -18℃ to -22℃, while in a conventional air conditioning scenario, it is typically set to 22℃ to 26℃. The control module then calculates the temperature deviation value by subtracting the actual refrigerated space temperature collected by the monitoring module at the current sampling moment from the target cooling temperature. The temperature deviation value objectively reflects the degree to which the current ambient temperature deviates from the set target; a larger value indicates a higher heat load demand.

[0039] To convert the temperature deviation value into a specific speed command, the control module calls the built-in discrete incremental proportional-integral-derivative control algorithm. The specific algorithm formula is as follows: ΔN=Kp*[e(k)-e(k-1)]+Ki*e(k)+Kd*[e(k)-2*e(k-1)+e(k-2)]; In the formula, ΔN represents the speed adjustment amount in revolutions per minute (rpm); e(k) represents the temperature deviation value calculated at the current sampling time; e(k-1) represents the temperature deviation value stored at the previous sampling time; and e(k-2) represents the temperature deviation value stored at the time before that. Kp represents the proportional coefficient, which is set based on the system's temperature response speed requirements. Its value is usually set between 50 and 150 to quickly respond to the current heat load gap. Ki represents the integral coefficient, which is set based on the system's time tolerance for eliminating steady-state errors. Its value is usually set between 5 and 20 to ensure that the actual cooling space temperature can eventually stabilize at the target cooling temperature. Kd represents the derivative coefficient, which is set based on the system's damping requirements for suppressing temperature overshoot. Its value is usually set between 10 and 50 to predict temperature change trends and suppress temperature overshoot in advance.

[0040] The control module superimposes the calculated speed adjustment ΔN with the current compressor speed to obtain the initial target speed. To prevent the compressor from operating under overload or the lubricating oil from failing to return smoothly due to excessively low speed, the control module limits the initial target speed using preset maximum and minimum speeds. The preset maximum speed is set based on the electromagnetic design limits and mechanical strength of the compressor motor, typically ranging from 6000 rpm to 9000 rpm; the preset minimum speed is set based on maintaining a minimum refrigerant flow rate to ensure compressor oil return, typically ranging from 900 rpm to 1200 rpm. When the initial target speed exceeds the aforementioned upper and lower limits, the boundary value is forcibly applied; when the initial target speed is within the safe range, it is directly used as the final target compressor speed. Through the aforementioned calculations, the control module can plan the operating frequency of the variable frequency compressor in real time and smoothly according to the dynamic changes in ambient temperature, avoiding frequent start-stop cycles and energy waste caused by fixed-frequency compressor operation.

[0041] S1022. Based on the low-pressure side pipeline pressure and the preset refrigerant pressure-saturation temperature mapping relationship, determine the evaporation saturation temperature, and calculate the difference between the evaporator outlet temperature and the evaporation saturation temperature to obtain the actual superheat. After establishing the operating baseline for the variable frequency compressor, the control module needs to perform a microscopic assessment of the heat exchange state inside the evaporator to ensure the safety and efficiency of the refrigeration cycle. The control module extracts the low-pressure side pipeline pressure collected by the monitoring module and calls the preset refrigerant pressure-saturation temperature mapping relationship in the underlying memory. In engineering thermodynamics, for refrigerants in a gas-liquid coexisting state, there is a strict one-to-one correspondence between pressure and temperature. Based on standard thermodynamic property experimental data of specific refrigerants, researchers used the Antoine equation for curve fitting to form the preset refrigerant pressure-saturation temperature mapping relationship. The control module uses this preset mapping relationship to convert the low-pressure side pipeline pressure into the evaporation saturation temperature. The specific conversion formula is: T_sat=B / (A-ln(P_low))-C; where T_sat represents the evaporation saturation temperature in degrees Celsius (°C); P_low represents the low-pressure side pipeline pressure in megapascals (MPa); and A, B, and C represent Antoine constants determined by the type of refrigerant. The Antoine constant is determined based on the physicochemical properties of the refrigerant. For R32 refrigerant, constant A is typically calibrated between 14.0 and 15.0, constant B between 2000 and 2500, and constant C between 20.0 and 30.0. The control module substitutes the low-pressure side pipeline pressure into the aforementioned formula to calculate the evaporation saturation temperature under the current pressure environment.

[0042] Subsequently, the control module extracts the evaporator outlet temperature synchronously collected by the monitoring module. The control module calculates the difference between the evaporator outlet temperature and the evaporation saturation temperature using the formula: SH_act = T_out - T_sat; where SH_act represents the actual superheat and T_out represents the evaporator outlet temperature. The actual superheat objectively characterizes the temperature rise caused by the pure gaseous refrigerant absorbing heat from the environment after complete vaporization at the evaporator end. Accurately obtaining the actual superheat effectively prevents compressor liquid slugging failures due to incomplete refrigerant evaporation, while also avoiding wasted evaporator heat exchange area caused by excessive superheat, providing reliable physical feedback for precise adjustment of the electronic expansion valve opening.

[0043] S1023. Calculate the superheat deviation between the actual superheat and the preset target superheat, and determine the expansion valve feedforward compensation amount based on the target compressor speed; After obtaining the actual superheat, the control module needs to calculate the superheat deviation between the actual superheat and the preset target superheat to provide a basis for the routine feedback adjustment of the electronic expansion valve. However, in a variable frequency refrigeration system, when the target compressor speed changes, the refrigerant mass flow rate inside the system changes instantaneously. If only the superheat deviation is relied upon for lagging feedback adjustment, it can easily lead to drastic fluctuations in the low-pressure side pipeline pressure, and even trigger compressor liquid slugging or low-pressure shutdown protection. To overcome the physical lag of single feedback control, the control module introduces a feedforward compensation mechanism. By sensing the changing trend of the compressor speed in advance and combining it with the current safety margin and heat load status of the system, it dynamically calculates the opening compensation amount of the electronic expansion valve, thereby achieving precise coordinated control of the compressor speed and the expansion valve opening. Specifically, this includes the following steps.

[0044] Obtain the current compressor speed and calculate the speed change between the target compressor speed and the current compressor speed; The low-pressure safety margin is determined based on the difference between the low-pressure side pipeline pressure and the preset low-pressure protection threshold, wherein the preset low-pressure protection threshold is greater than the preset evacuation threshold. The current heat load coefficient is determined based on the temperature deviation value. The dynamic feedforward gain coefficient is determined based on the low-pressure safety margin and the current heat load coefficient. When the speed change is greater than zero, the dynamic feedforward gain coefficient is negatively correlated with the low-pressure safety margin and positively correlated with the current heat load coefficient. The product of the speed change and the preset basic feedforward coefficient is determined as the basic opening compensation amount; The initial feedforward compensation amount is obtained by performing gain correction on the basic opening compensation amount based on the dynamic feedforward gain coefficient. The initial feedforward compensation amount is limited according to the preset upper limit and lower limit of the opening compensation to obtain the feedforward compensation amount of the expansion valve.

[0045] In a variable frequency refrigeration system, a change in compressor speed can instantly disrupt the original mass flow balance of the refrigeration cycle. To overcome the physical lag caused by single superheat feedback control, the control module executes feedforward compensation logic to achieve precise coordination between the opening of the electronic expansion valve and the compressor speed.

[0046] The control module first obtains the current compressor speed by reading the low-level registers of the variable frequency compressor driver. To quantify the degree of refrigerant flow disturbance the system will face, the control module calculates the difference between the previously calculated target compressor speed and the current compressor speed to obtain the speed change. The speed change objectively reflects the acceleration / deceleration trend and magnitude of the variable frequency compressor, providing a kinematic feedforward reference for subsequent advance adjustment of the electronic expansion valve.

[0047] Before implementing feedforward regulation, the current low-pressure operating boundary of the system must be assessed. The control module extracts the low-pressure side piping pressure and calculates the difference between it and the preset low-pressure protection threshold to obtain the low-pressure safety margin. The preset low-pressure protection threshold is set based on the physical requirements of preventing water condensation and freezing inside the evaporator and preventing negative pressure external air from seeping into the system. For R32 refrigerant, the preset low-pressure protection threshold is typically set to 0.15 MPa to 0.25 MPa. Furthermore, to differentiate between normal operating protection and emergency response under extreme leakage conditions, the preset low-pressure protection threshold is numerically strictly greater than the preset evacuation threshold (typically set to 0.02 MPa to 0.05 MPa). The low-pressure safety margin represents the buffer space between the current system low-pressure state and the triggering of shutdown protection; the smaller the value, the closer the system is to the low-pressure danger boundary.

[0048] To enable feedforward regulation to adapt to complex operating conditions, the control module introduces a comprehensive evaluation mechanism for heat load and pressure. The control module determines the current heat load coefficient based on the previously calculated temperature deviation value. The specific calculation logic is as follows: the control module extracts a preset maximum temperature deviation threshold, which is set based on the maximum allowable temperature difference range of the refrigeration unit under extreme design conditions, typically set to 10℃ to 15℃; the control module divides the temperature deviation value by the preset maximum temperature deviation threshold to obtain a dimensionless load proportional factor, and adds the load proportional factor to the basic constant 1.0 to calculate the current heat load coefficient. Through the aforementioned normalized mapping calculation, the current heat load coefficient objectively reflects the urgent demand for cooling capacity from the environment; the larger the temperature deviation, the larger the current heat load coefficient.

[0049] Subsequently, the control module determines the dynamic feedforward gain coefficient based on the low-pressure safety margin and the current heat load coefficient. The dynamic feedforward gain coefficient is a dimensionless multiplier used to physically amplify or reduce the base adjustment. To handle different speed variation trends, the control module employs a piecewise calculation logic: When the speed change is greater than zero, it means the variable frequency compressor is about to accelerate, and the pressure in the low-pressure side pipeline of the system will drop instantaneously due to the suction effect. To prevent the pressure from falling below the protection boundary and to respond quickly to the load, the algorithm specifies that the dynamic feedforward gain coefficient is negatively correlated with the low-pressure safety margin and positively correlated with the current heat load coefficient. The specific algorithm formula is: K_gain=1.0+(W1*C_load)+(W2 / M_low); where K_gain represents the dynamic feedforward gain coefficient; C_load represents the current heat load coefficient; M_low represents the low-pressure safety margin; and W1 and W2 are preset weighting constants. Under acceleration conditions, the greater the ambient heat load or the closer the low-pressure side is to the protection boundary, the greater the calculated dynamic feedforward gain coefficient, thus prompting the electronic expansion valve to open more aggressively.

[0050] When the speed change is less than zero, it means the variable frequency compressor is about to decelerate, and the amount of refrigerant drawn into the system decreases instantaneously. If the electronic expansion valve fails to close in time, excess liquid refrigerant will rush into the evaporator, causing liquid slugging in the compressor. To quickly curb the risk of liquid slugging, the algorithm specifies that the dynamic feedforward gain coefficient is positively correlated with the low-pressure safety margin and negatively correlated with the current heat load coefficient. The specific algorithm formula is: K_gain=1.0+(W3 / C_load)+(W4*M_low); where W3 and W4 are preset weighting constants. Under deceleration conditions, the larger the low-pressure safety margin (indicating higher low pressure, higher evaporation pressure, and greater risk of liquid slugging) or the smaller the heat load (indicating that no extra cooling capacity is needed), the larger the calculated dynamic feedforward gain coefficient, thus amplifying the negative compensation amount and prompting the electronic expansion valve to close more aggressively.

[0051] After determining the gain coefficient, the control module retrieves the preset basic feedforward coefficient and multiplies the speed change by the preset basic feedforward coefficient to calculate the basic opening compensation amount. The preset basic feedforward coefficient is set based on the mechanical matching relationship between the cylinder displacement of the variable frequency compressor and the flow cross-sectional area of ​​the electronic expansion valve orifice. It represents the theoretical number of steps the expansion valve needs to follow for each revolution of the compressor, and its specific value range is usually calibrated between 0.05 steps / rpm and 0.15 steps / rpm. The control module uses the calculated dynamic feedforward gain coefficient to perform multiplicative gain correction on the basic opening compensation amount to obtain the initial feedforward compensation amount.

[0052] Considering that excessive instantaneous opening changes may cause severe system pressure fluctuations, the control module uses preset upper and lower opening compensation limits to limit the initial feedforward compensation. The preset upper opening compensation limit is set based on the maximum permissible instantaneous liquid supply surge of the evaporator, typically set to +100 to +150 steps; the preset lower opening compensation limit is set based on the requirement to maintain the minimum return gas cooling flow rate of the compressor, typically set to -50 to -80 steps. When the initial feedforward compensation exceeds the above range, the boundary value is forcibly taken, and the final output is a safe and reliable expansion valve feedforward compensation.

[0053] For example, consider the acceleration condition: Assume the current compressor speed is 3000 rpm, the target compressor speed is 4000 rpm, and the speed change is +1000 rpm. The current low-pressure side pipeline pressure is 0.45 MPa, the preset low-pressure protection threshold is 0.20 MPa, and the low-pressure safety margin is 0.25 MPa. The temperature deviation is 3℃, and the preset maximum temperature deviation threshold is 15℃. The calculated current heat load coefficient is 1.0 + (3 / 15) = 1.2. Substituting into the acceleration gain formula (assuming W1 is 0.5 and W2 is 0.1), the calculated dynamic feedforward gain coefficient K_gain = 1.0 + (0.5 * 1.2) + (0.1 / 0.25) = 2.0. The preset basic feedforward coefficient is 0.1 steps / rpm, and the basic opening compensation is +100 steps. After gain correction, the initial feedforward compensation is +200 steps. Limited by the preset opening compensation limit of +150 steps, the feedforward compensation amount of the expansion valve was finally determined to be +150 steps.

[0054] Example of deceleration condition: Assume the current compressor speed is 4000 rpm, the target compressor speed is 3000 rpm, and the speed change is -1000 rpm. The current low-pressure side pipeline pressure is 0.80 MPa, the preset low-pressure protection threshold is 0.20 MPa, and the low-pressure safety margin is 0.60 MPa. The temperature deviation is 0.5℃, and the calculated current heat load coefficient is 1.0 + (0.5 / 15) ≈ 1.03. Substituting into the deceleration gain formula (assuming W3 is 0.2 and W4 is 1.5), the calculated dynamic feedforward gain coefficient K_gain = 1.0 + (0.2 / 1.03) + (1.5 * 0.60) ≈ 2.09. The basic opening compensation is -1000 * 0.1 = -100 steps. After gain correction, the initial feedforward compensation is -209 steps. Limited by the preset opening compensation lower limit of -80 steps, the feedforward compensation amount of the expansion valve was finally determined to be -80 steps, prompting the valve to close quickly to prevent liquid slugging.

[0055] S1024. Determine the target expansion valve opening based on the superheat deviation and the expansion valve feedforward compensation amount, and use the target compressor speed and the target expansion valve opening as the refrigeration power adjustment parameters; After obtaining the actual superheat and the expansion valve feedforward compensation, the control module needs to integrate the hysteresis-based thermodynamic state-based lag feedback regulation with the kinematic state-based advance feedforward regulation to calculate the final electronic expansion valve action command. The control module first extracts the preset target superheat stored internally. The preset target superheat is set based on the physical balance between the refrigerant's heat exchange efficiency inside the evaporator and the compressor's suction safety. Setting the value too low will result in incomplete evaporation of the liquid refrigerant, causing liquid slugging in the compressor; setting the value too high will result in insufficient utilization of the evaporator's effective heat exchange area and excessively high compressor discharge temperature. For conventional cold storage or air conditioning applications, the preset target superheat is typically set between 4°C and 8°C. The control module then calculates the difference between the previously calculated actual superheat and the preset target superheat to obtain the superheat deviation. The superheat deviation objectively reflects the degree of mismatch between the current liquid supply inside the evaporator and the actual heat exchange demand.

[0056] To eliminate superheat deviation, the control module inputs the superheat deviation into the built-in proportional-integral (PI) control algorithm to calculate the basic feedback adjustment. The basic feedback adjustment represents the number of steps the electronic expansion valve needs to adjust to bring the actual superheat back to the preset target superheat under steady-state conditions. Subsequently, the control module linearly superimposes the basic feedback adjustment, the previously calculated expansion valve feedforward compensation, and the current actual expansion valve opening. The specific calculation formula is: Step_target = Step_current + ΔStep_PI + ΔStep_FF; where Step_target represents the initial target opening after superposition; Step_current represents the current actual expansion valve opening; ΔStep_PI represents the basic feedback adjustment calculated from the superheat deviation; and ΔStep_FF represents the expansion valve feedforward compensation previously calculated based on the speed change. Through the aforementioned superposition calculations, the control module implements composite control logic: when the compressor speed changes abruptly, the expansion valve feedforward compensation amount dominates the opening change, realizing rapid coarse adjustment of flow rate and preventing drastic pressure fluctuations; when the system enters steady-state operation, the basic feedback adjustment amount dominates the opening change, realizing precise fine adjustment of superheat.

[0057] Considering the physical limits of the electronic expansion valve's mechanical structure, the control module uses preset maximum and minimum opening thresholds to limit the initial target opening. The preset maximum opening threshold is set based on the number of steps corresponding to the maximum flow cross-sectional area when the expansion valve needle is completely disengaged from the valve seat, typically set to 450 to 480 steps. The preset minimum opening threshold is set based on the number of steps corresponding to the minimum flow cross-sectional area required to maintain the minimum refrigerant circulation volume to prevent low-pressure shutdown protection, typically set to 40 to 60 steps. When the initial target opening exceeds the aforementioned physical boundaries, the boundary values ​​are forcibly applied to obtain a safe and reliable target expansion valve opening. Finally, the control module packages the target compressor speed, representing the macroscopic cooling capacity demand, and the target expansion valve opening, representing the microscopic flow matching, into a single data set, which is then used as the cooling power adjustment parameter sent to the underlying actuators.

[0058] For example: Assume the system's preset target superheat is 5℃, and the currently calculated actual superheat is 8℃, resulting in a superheat deviation of 3℃ (indicating insufficient liquid supply). The control module inputs this 3℃ superheat deviation into the PI algorithm, calculating a basic feedback adjustment of +15 steps. Given that the current actual expansion valve opening is 200 steps, and the previously calculated expansion valve feedforward compensation is +150 steps (due to compressor acceleration), substituting these into the superposition formula, the initial target opening = 200 + 15 + 150 = 365 steps. Since 365 steps falls between the preset minimum opening threshold of 50 steps and the preset maximum opening threshold of 480 steps, the limiting is not triggered, and the control module ultimately determines the target expansion valve opening as 365 steps. The control module then packages the target compressor speed (e.g., 4000 rpm) and the target expansion valve opening (365 steps) to generate cooling power adjustment parameters.

[0059] S1025. Control the operation of the variable frequency compressor according to the target compressor speed, and control the opening of the electronic expansion valve according to the target expansion valve opening.

[0060] After the control module generates the cooling power adjustment parameters, the system enters the physical execution phase, translating the digital control commands into mechanical actions of the core components in the refrigeration cycle. The control module sends the target compressor speed from the cooling power adjustment parameters to the variable frequency compressor driver via its internal RS485 or CAN communication bus. Upon receiving the target compressor speed, the variable frequency compressor driver's internal inverter circuit dynamically adjusts the frequency and voltage of the three-phase AC power output to the stator windings of the variable frequency compressor according to the Space Vector Pulse Width Modulation (SVPWM) algorithm. As the power supply frequency changes, the rotational frequency of the rotor inside the variable frequency compressor smoothly transitions to the target compressor speed, thereby altering the refrigerant gas suction and compression volume per unit time in the cylinder, achieving physical adjustment of the overall refrigerant mass flow rate of the system.

[0061] Synchronously, the control module converts the target expansion valve opening in the cooling power adjustment parameters into specific pulse control signals and sends them to the stepper motor drive circuit of the electronic expansion valve. Based on the difference between the target expansion valve opening and the current opening, the stepper motor drive circuit outputs a corresponding number and phase sequence of drive pulses to the stator coil inside the electronic expansion valve. These drive pulses generate a rotating magnetic field in the stator coil, driving the permanent magnet rotor to rotate. The rotor's rotational motion is converted into the linear up-and-down movement of the valve needle through an internal threaded structure. This valve needle displacement precisely changes the flow cross-sectional area at the valve orifice, thus physically adjusting the degree of throttling and pressure reduction of the liquid refrigerant and the liquid supply volume according to the target expansion valve opening.

[0062] Through the aforementioned synchronous execution process, the refrigeration unit completes a full closed-loop control, from environmental parameter acquisition, thermodynamic state assessment, composite algorithm calculation to the movement of mechanical components. The variable frequency compressor and electronic expansion valve work in concert under the unified command of the refrigeration power adjustment parameters, satisfying the dynamic demands of the external environment on cooling capacity while maintaining stable pressure and superheat within the refrigeration cycle loop. This effectively avoids the system oscillation and energy efficiency degradation problems that are prone to occur in traditional independent control modes.

[0063] S103. When the refrigerant leakage concentration is greater than or equal to the preset safety threshold, control the liquid supply valve to close and control the electronic expansion valve to maintain the preset evacuation opening, so that the pipe section between the liquid supply valve and the electronic expansion valve is connected to the low-pressure side pipe through the electronic expansion valve, the evaporator and the low-pressure side pipe, forming an evacuation channel connected to the suction end of the variable frequency compressor. During the operation of the refrigeration unit, the monitoring module continuously collects the refrigerant leakage concentration in the environment where the refrigeration unit is located. The control module compares the real-time refrigerant leakage concentration with the aforementioned preset safety threshold written in the underlying memory. When the refrigerant leakage concentration is greater than or equal to the preset safety threshold, it indicates that there is damage to the refrigeration unit's piping and the leakage has reached a critical state that could trigger a safety accident. At this time, the control module must immediately interrupt the normal refrigeration power adjustment logic and force the system into emergency evacuation and recovery mode.

[0064] To prevent the refrigerant from spreading further into the leak area, the control module first sends a power-off or closing command to the liquid supply valve located on the high-pressure side pipeline, causing the liquid supply valve to close instantly. Physically located between the condenser and the electronic expansion valve, closing the liquid supply valve cuts off the physical path for the large amount of high-pressure liquid refrigerant stored inside the condenser to flow into the low-pressure side pipeline and evaporator, preventing further expansion of the leak at its source.

[0065] Simultaneously with closing the liquid supply valve, to safely transfer the refrigerant already present on the low-pressure side and part of the high-pressure pipeline, the control module sends a pulse control signal to the stepper motor drive circuit of the electronic expansion valve. This causes the electronic expansion valve to deviate from conventional superheat feedback regulation, forcing it to operate and maintain a preset evacuation opening. The preset evacuation opening is set based on balancing the refrigerant suction rate and preventing liquid slugging in the compressor. If the opening is set too high, residual liquid refrigerant may directly flood into the compressor, causing mechanical damage; if the opening is set too low, it will lead to excessive evacuation resistance, prolonging the duration of the dangerous situation. The preset evacuation opening is typically set to 30% to 50% of the maximum design opening of the electronic expansion valve, with a specific value range usually between 150 and 250 steps.

[0066] By closing the liquid supply valve and directional opening of the electronic expansion valve, the fluid topology within the refrigeration cycle loop undergoes a fundamental change. The pipe section between the liquid supply valve and the electronic expansion valve is physically connected via the electronic expansion valve, which maintains a preset evacuation opening, the evacuation evacuation valve, and the low-pressure side pipe, together constructing an evacuation channel directly to the suction end of the inverter compressor. The core purpose of constructing this evacuation channel is to allow the mechanical suction power of the inverter compressor itself to be directly used to forcibly extract refrigerant gas from high-risk leakage areas (usually the indoor evacuation evacuator and low-pressure side pipes), and to pressurize it across the compressor to the high-pressure side pipe, which is physically isolated by the liquid supply valve, for temporary storage. This reduces the amount of refrigerant in the leakage area in the shortest possible time, completely eliminating the risk of combustion and explosion.

[0067] S104. Evacuation status evaluation is performed on the operating status parameters to obtain evacuation status parameters, and the target evacuation speed is determined based on the evacuation status parameters. The variable frequency compressor is controlled to operate at the target evacuation speed to pressurize the refrigerant in the evacuation channel to the high-pressure side pipeline. When performing a evacuation status assessment, the operating status parameters also include the high-pressure side pipeline pressure. In emergency evacuation mode, the refrigerant is continuously extracted by the inverter compressor and temporarily stored in the high-pressure side pipeline, inevitably leading to a continuous increase in the high-pressure side pipeline pressure. Accurately obtaining the high-pressure side pipeline pressure can objectively reflect the current physical load state of the high-pressure side, providing a core data foundation for subsequent calculations of the real-time compression ratio of the inverter compressor, thereby effectively preventing mechanical overload of the compressor or rupture of the high-pressure side pipeline due to excessive pressure.

[0068] After successfully constructing the evacuation channel, the refrigeration unit enters the substantive refrigerant recovery phase. To quickly and safely deliver the refrigerant from the evacuation channel to the high-pressure side pipeline, a variable frequency compressor is required to provide the suction power. However, during evacuation, if the compressor speed is set too low, the suction rate may not be able to keep up with the rate of refrigerant leakage into the environment, failing to eliminate the risk of combustion and explosion in time. If the compressor speed is set too high, as the pressure in the low-pressure side pipeline continuously decreases and the pressure in the high-pressure side pipeline continuously increases, the operating pressure ratio of the variable frequency compressor will rise sharply, easily leading to excessive exhaust temperature or mechanical damage. Therefore, the control module needs to comprehensively assess the severity of leakage diffusion and the actual evacuation progress, dynamically calculate the initial evacuation speed, and introduce a safety limiting mechanism based on the real-time compression ratio to achieve the most efficient refrigerant recovery while ensuring the mechanical and thermodynamic safety of the variable frequency compressor. Figure 3 This is a flowchart for determining the target evacuation speed. The following is in conjunction with... Figure 3 Step S104 will be described in detail.

[0069] S201. Determine the low-pressure side pressure drop rate and the leakage concentration rise rate based on the drop rate of the low-pressure side pipeline pressure within the preset time window and the rise rate of the refrigerant leakage concentration within the preset time window, respectively. In emergency evacuation and recovery mode, the variable frequency compressor needs to provide sufficient suction power to quickly evacuate the refrigerant from the low-pressure side piping. However, a fixed evacuation speed cannot adapt to leakage conditions with varying degrees of damage. To dynamically match suction capacity with leakage diffusion rate, the control module needs to perform real-time quantitative assessment of the current evacuation status.

[0070] The control module first extracts the low-pressure side pipeline pressure and refrigerant leakage concentration continuously collected by the monitoring module within a preset time window. The preset time window is set based on the system's sensitivity requirements to changes in leakage conditions, typically between 3 and 5 seconds. The control module calculates the decrease in low-pressure side pipeline pressure within the preset time window and divides this decrease by the length of the preset time window to determine the low-pressure side pressure drop rate. Similarly, the control module calculates the increase in refrigerant leakage concentration within the preset time window and divides this increase by the length of the time window to determine the leakage concentration rise rate. The low-pressure side pressure drop rate objectively reflects the actual suction and venting capacity of the variable frequency compressor, while the leakage concentration rise rate directly characterizes the severity of refrigerant diffusion into the external environment.

[0071] S202. The rate of decrease in low-pressure side pressure and the rate of increase in leakage concentration are used as the evacuation state parameters, and the basic evacuation speed is determined according to the rate of increase in leakage concentration, wherein the basic evacuation speed is positively correlated with the rate of increase in leakage concentration. The control module uses both the low-pressure side pressure drop rate and the leakage concentration rise rate as evacuation state parameters to assess the current system hazard level and pumping effectiveness. To ensure that the pumping action can outpace leakage propagation, the control module determines the base evacuation speed based on the leakage concentration rise rate. The base evacuation speed represents the basic mechanical pumping power required by the system to curb the current leakage trend. The algorithm specifies a positive correlation between the base evacuation speed and the leakage concentration rise rate. In practice, the control module calls the built-in linear mapping function, specifically the formula: N_base = K_leak * V_leak + N_min; where N_base represents the base evacuation speed; V_leak represents the leakage concentration rise rate; K_leak represents the preset leakage gain coefficient; and N_min represents the preset minimum safe speed. The preset leakage gain coefficient is set based on the physical conversion relationship between the cylinder volumetric flow rate per unit speed of the variable frequency compressor and the diffusion rate of the refrigerant in a specific space. This converts the physical dimension of the concentration change rate into the physical dimension of mechanical speed, and its value is typically calibrated between 1,000,000 and 2,000,000 (rpm·s) / (kg / m³). The preset minimum safe speed is set based on the minimum power requirement to maintain normal circulation of the lubricating oil inside the variable frequency compressor, and is typically set between 1,000 and 1,500 rpm. Through the aforementioned mapping, the greater the rate of increase in leakage concentration, the higher the calculated base evacuation speed, thus providing a strong feedforward suction flow rate in the initial stage of leakage.

[0072] S203. Calculate the rate deviation between the low-pressure side pressure drop rate and the preset target drop rate, and determine the evacuation speed compensation amount based on the rate deviation; After determining the basic suction power, considering the actual pipeline resistance and the fact that the evaporation of residual liquid refrigerant will delay the pressure drop, the control module needs to perform closed-loop correction based on the actual pipeline evacuation effect. The control module extracts the preset target evacuation rate, which is set based on the time constraint required for the refrigeration unit to complete safe evacuation under standard operating conditions, typically set to 0.01 MPa / s to 0.03 MPa / s. The control module calculates the rate deviation by subtracting the preset target evacuation rate from the low-pressure side pressure drop rate. The rate deviation reflects the gap between the actual evacuation progress and the expected target. The control module inputs the rate deviation into the proportional control algorithm to calculate the evacuation speed compensation. The specific calculation formula is: N_comp = K_p * E_rate; where N_comp represents the evacuation speed compensation; E_rate represents the rate deviation; and K_p represents the preset proportional control coefficient. The preset proportional control coefficient is set based on the transfer function gain of the variable frequency compressor speed change on the low-pressure side pipeline pressure response, and is usually set to 30,000 to 50,000 rpm / (MPa / s). When the actual low-pressure side pressure drop rate is less than the preset target drop rate, the rate deviation is positive, and the generated evacuation speed compensation is positive, which is used to further increase the speed to accelerate evacuation; otherwise, the output is zero or negative.

[0073] For example: Assume a preset time window of 5 seconds. The control module detects a 0.05 MPa decrease in low-pressure side pipeline pressure within 5 seconds, calculating the low-pressure side pressure drop rate as 0.01 MPa / s. Simultaneously, the refrigerant leakage concentration increases by 0.01 kg / m³ within 5 seconds, calculating the leakage concentration increase rate as 0.002 (kg / m³) / s. The control module uses these two rates as evacuation status parameters. Based on the leakage concentration increase rate of 0.002 (kg / m³) / s, substituting it into the mapping function (setting a preset leakage gain coefficient of 1,000,000 and a preset minimum safe speed of 1,000 rpm), the basic evacuation speed is calculated as 1,000,000 * 0.002 + 1,000 = 3,000 rpm. The system's preset target pressure drop rate is 0.02 MPa / s. The control module calculates the rate deviation as 0.02 - 0.01 = 0.01 MPa / s. Substituting the rate deviation of 0.01 MPa / s into the proportional control algorithm (with a preset proportional control coefficient of 50000), the calculated evacuation speed compensation is 50000 * 0.01 = +500 rpm. The control module adds the base evacuation speed of 3000 rpm to the +500 rpm compensation, ultimately determining the initial evacuation speed to be 3500 rpm.

[0074] S204. The sum of the basic evacuation speed and the evacuation speed compensation amount is determined as the initial evacuation speed; To generate comprehensive control commands that balance external leakage suppression requirements with the actual evacuation progress of the internal pipeline, the control module needs to physically integrate feedforward power and feedback correction. The control module extracts the base evacuation speed calculated based on the leakage concentration rise rate and the evacuation speed compensation calculated based on the rate deviation, and performs a linear addition operation on these two values ​​in the underlying microprocessor. The calculated sum is determined as the initial evacuation speed. The initial evacuation speed represents the ideal target speed under conditions where the mechanical and thermodynamic limit constraints of the variable frequency compressor have not yet been introduced. Through the aforementioned linear superposition logic, the initial evacuation speed inherits the forward-looking power reserve of the base evacuation speed to cope with refrigerant diffusion, and also integrates the closed-loop correction of the evacuation speed compensation for the actual suction resistance inside the pipeline, thereby ensuring that the variable frequency compressor can output suction power best matched to the current complex leakage conditions. For example, assuming the control module calculates a base evacuation speed of 3000 rpm and a evacuation speed compensation of +500 rpm, the control module adds 3000 rpm and +500 rpm to determine the initial evacuation speed as 3500 rpm, providing an accurate numerical reference for subsequent safety limiting processing.

[0075] S205. Determine the real-time compression ratio based on the pressure of the high-pressure side pipeline and the pressure of the low-pressure side pipeline, and perform safety limiting processing on the initial evacuation speed based on the real-time compression ratio to obtain the target evacuation speed.

[0076] After determining the initial evacuation speed, the control logic of the refrigeration unit must shift to assessing the underlying physical safety of the inverter compressor. In emergency evacuation recovery mode, the inverter compressor continuously extracts refrigerant from the low-pressure side pipeline and forcibly pumps it into the high-pressure side pipeline, which is physically isolated by the liquid supply valve, for temporary storage. This forced transfer of fluid mass inevitably leads to a continuous decrease in the low-pressure side pipeline pressure, while the high-pressure side pipeline pressure continuously increases. This drastic difference in pressure between the inlet and outlet ends causes a sharp increase in the mechanical stress and thermodynamic work intensity inside the inverter compressor, which can easily lead to scroll plate breakage or excessive exhaust temperature causing lubricating oil carbonization.

[0077] To quantify the actual physical load currently borne by the variable frequency compressor, the control module extracts the high-pressure side and low-pressure side pipeline pressures collected in real time by the monitoring module. Before performing numerical calculations, to comply with thermodynamic calculation specifications, the control module ensures that the extracted high-pressure side and low-pressure side pipeline pressures are absolute pressure values ​​(if the sensors collect gauge pressure, standard atmospheric pressure needs to be added in the underlying program for conversion). Subsequently, the control module divides the high-pressure side pipeline pressure by the low-pressure side pipeline pressure, performing a division operation. The specific calculation formula is: R_comp = P_high / P_low; where R_comp represents the real-time compression ratio; P_high represents the high-pressure side pipeline pressure; and P_low represents the low-pressure side pipeline pressure. The real-time compression ratio calculated through the aforementioned division operation is a dimensionless thermodynamic core parameter. The real-time compression ratio objectively and accurately characterizes the amount of mechanical work expended by the variable frequency compressor cylinder or scroll plate to overcome the intake and exhaust pressure difference at the current instant, as well as the potential surge trend of exhaust temperature, thus providing the most direct physical criterion for subsequent safety limiting of the initial evacuation speed.

[0078] After calculating the real-time compression ratio, the control module must rigorously assess the underlying physical safety boundaries of the variable frequency compressor to prevent the continuously increasing intake and exhaust pressure differential from causing mechanical overload or exhaust temperature runaway. To achieve a physical balance between maximizing refrigerant recovery efficiency and ensuring underlying hardware safety, the control module needs to introduce a dynamic limiting mechanism based on the real-time compression ratio. This includes the following steps.

[0079] The real-time compression ratio is compared with a preset compression ratio safety threshold. When the real-time compression ratio is less than or equal to the preset compression ratio safety threshold, the initial evacuation speed is limited based on the preset upper limit and lower limit of the evacuation speed to obtain the target evacuation speed. When the real-time compression ratio is greater than the preset compression ratio safety threshold, a frequency reduction and limiting coefficient is determined based on the over-limit difference between the real-time compression ratio and the preset compression ratio safety threshold. The frequency reduction and limiting coefficient is greater than zero and less than one, and the frequency reduction and limiting coefficient is negatively correlated with the over-limit difference. Based on the frequency reduction and amplitude limiting coefficient, the initial evacuation speed is corrected by frequency reduction to obtain the corrected evacuation speed; The target evacuation speed is obtained by limiting the modified evacuation speed based on the preset upper limit and the preset lower limit of the evacuation speed.

[0080] After obtaining the real-time compression ratio, the control module needs to rigorously evaluate the underlying physical safety boundaries of the inverter compressor to determine whether a forced reduction in the previously calculated initial evacuation speed is necessary. The control module first compares the real-time compression ratio with a preset compression ratio safety threshold written in the underlying memory. This preset safety threshold is based on the thermodynamic safety operating envelope provided by the inverter compressor manufacturer, representing the maximum intake and exhaust pressure ratio the compressor can withstand without exhaust temperature runaway or mechanical damage to the scroll plate. For R32 or R410A refrigerants used in conventional air conditioning systems, the preset compression ratio safety threshold is typically set between 8.0 and 12.0.

[0081] When the comparison results show that the real-time compression ratio is less than or equal to the preset compression ratio safety threshold, it indicates that the current thermodynamic state of the variable frequency compressor is within a safe range, and the intake and exhaust pressure difference has not yet posed a threat to the mechanical structure, so there is no need for forced frequency reduction intervention. At this time, the control module only needs to perform conventional physical extreme value limiting on the initial evacuation speed based on the preset upper limit and lower limit of the evacuation speed. The preset upper limit of the evacuation speed is set based on the maximum design operating frequency of the variable frequency compressor drive motor and the maximum output current limit of the inverter, and is usually set to 6000 rpm to 8000 rpm; the preset lower limit of the evacuation speed is set based on the minimum mechanical power required to maintain normal circulation of the lubricating oil inside the compressor, and is usually set to 1000 rpm to 1500 rpm. The control module determines whether the initial evacuation speed falls within the range formed by the preset upper limit and lower limit of the evacuation speed. If it is within the range, the initial evacuation speed is directly used as the target evacuation speed; if it exceeds the upper limit, the upper limit value is used as the target evacuation speed; if it is below the lower limit, the lower limit value is used as the target evacuation speed. By using the aforementioned extreme value limiting, it can be ensured that the speed command output by the variable frequency compressor strictly conforms to the physical constraints of the motor hardware, under the premise of thermodynamic safety.

[0082] Example of safe operating conditions: Assume a real-time compression ratio of 7.5 and a preset safe compression ratio threshold of 10.0. Since 7.5 is less than 10.0, the system is in a safe state. The control module extracts an initial evacuation speed of 5000 rpm, a preset upper limit of evacuation speed of 7000 rpm, and a preset lower limit of evacuation speed of 1200 rpm. Since 5000 rpm falls between 1200 rpm and 7000 rpm, the control module directly determines 5000 rpm as the target evacuation speed.

[0083] When the comparison results show that the real-time compression ratio is greater than the preset compression ratio safety threshold, it indicates that the variable frequency compressor is facing a serious overload risk, and continued operation is highly likely to cause irreversible hardware damage. To quickly alleviate the excessively high intake and exhaust pressure difference, the control module must immediately reduce the suction power. The control module first performs a subtraction operation to calculate the over-limit difference between the real-time compression ratio and the preset compression ratio safety threshold. The over-limit difference objectively quantifies the severity of the current operating condition deviating from the safety boundary. Subsequently, the control module determines the frequency reduction limiting coefficient based on the over-limit difference. The frequency reduction limiting coefficient is a dimensionless multiplier used to force proportional attenuation of the speed command, and its value is strictly limited to a range greater than zero and less than one. To achieve a dynamic protection effect where the frequency reduction amplitude increases with the severity of the over-limit, the algorithm specifies that the frequency reduction limiting coefficient is negatively correlated with the over-limit difference. The specific calculation formula is: C_limit=1-(K_drop*D_over); where C_limit represents the frequency reduction limiting coefficient; D_over represents the over-limit difference; and K_drop represents the preset frequency reduction sensitivity coefficient. The preset frequency reduction sensitivity coefficient is set based on the system's physical tolerance to pressure overshoot and the transmission delay of speed response, and is usually set to 0.05 to 0.15.

[0084] After calculating the frequency reduction limiting coefficient, the control module multiplies the coefficient by the initial evacuation speed. Based on the coefficient, the initial evacuation speed is corrected by frequency reduction, resulting in a corrected evacuation speed with a smaller value. Finally, to prevent the corrected speed from falling below the minimum requirement for maintaining lubricating oil circulation, the control module again limits the corrected evacuation speed based on preset upper and lower limits. Since the corrected evacuation speed is necessarily lower than the initial evacuation speed, this limitation is mainly used to prevent the corrected evacuation speed from falling below the preset lower limit. The value output after the aforementioned limiting process is the final target evacuation speed issued to the variable frequency compressor. By introducing a negative correlation between the over-limit difference and the frequency reduction limiting coefficient, the system can quickly and smoothly reduce the evacuation speed when hardware safety is threatened, effectively curbing the vicious rise in high-pressure side pipeline pressure.

[0085] Example of an over-limit operating condition: Assuming the evacuation operation progresses, the real-time compression ratio climbs to 12.0, while the preset compression ratio safety threshold is 10.0. The control module determines that 12.0 is greater than 10.0 and triggers frequency reduction protection. The control module calculates the over-limit difference as 12.0 - 10.0 = 2.0. Substituting into the formula (setting the preset frequency reduction sensitivity coefficient to 0.1), the frequency reduction limiting coefficient is calculated to be 1 - (0.1 * 2.0) = 0.8. The control module extracts the initial evacuation speed as 5000 rpm, multiplies 5000 rpm by 0.8, and obtains a corrected evacuation speed of 4000 rpm. Finally, the control module determines that 4000 rpm is between the preset lower limit of 1200 rpm and the preset upper limit of 7000 rpm, and ultimately determines 4000 rpm as the target evacuation speed, controlling the variable frequency compressor to operate at a reduced frequency to alleviate the high-pressure side load.

[0086] After determining the target evacuation speed, the control module needs to translate the numerical commands into actual mechanical actions to complete the refrigerant transfer across the pipeline. The control module converts the target evacuation speed into a corresponding pulse-width modulation (PWM) drive signal and sends this signal to the inverter of the variable frequency compressor. The inverter adjusts its output voltage and frequency based on the received signal, driving the motor of the variable frequency compressor to adjust its speed until the actual operating speed stabilizes at the target evacuation speed.

[0087] The variable frequency compressor operates continuously at the target evacuation speed, generating a continuous negative pressure suction force at its suction end within the evacuation channel. Residual refrigerant in the evacuation channel is continuously drawn into the compressor's compression chamber under the pressure difference. After mechanical compression, the refrigerant is converted to a high-temperature, high-pressure state and forcibly discharged from the compressor's discharge end. The discharged refrigerant flows along the pipeline to the high-pressure side pipeline. Because the liquid supply valve is closed, the high-pressure side pipeline and the condenser together form a physically isolated, sealed space. The refrigerant discharged from the variable frequency compressor is continuously compressed and accumulated within this sealed space formed by the high-pressure side pipeline and the condenser.

[0088] Through the continuous suction and compression operation of the variable frequency compressor, the refrigerant in the low-pressure side pipeline and evaporator is quickly and safely emptied, fundamentally cutting off the source of refrigerant leakage to the external environment. At the same time, the refrigerant is centrally sealed in the high-pressure side pipeline, providing the necessary physical prerequisite for the centralized recovery operation of the subsequent refrigerant recovery device.

[0089] S105. When the pressure of the low-pressure side pipeline is less than or equal to the preset evacuation threshold, or when the variable frequency compressor meets the preset evacuation stop condition, the control module controls the variable frequency compressor to stop running, and generates recovery control parameters according to the recovery status parameters. Based on the recovery control parameters, the refrigerant recovery device is controlled to recover the refrigerant in the high-pressure side pipeline through the recovery branch.

[0090] When the refrigerant recovery operation is triggered, the control module extracts the recovery status parameters including the pressure and remaining capacity of the recovery tank. The pressure of the recovery tank is collected in real time by a pressure sensor installed at the liquid end of the refrigerant recovery device, objectively reflecting the current physical load state of the fluid inside the receiving container; the remaining capacity of the recovery tank directly represents the physical space available for the receiving container to continue holding refrigerant.

[0091] When the pressure in the low-pressure side pipeline drops to less than or equal to the preset evacuation threshold, or when the variable frequency compressor triggers the preset evacuation stop condition, it indicates that the refrigerant in the low-pressure side pipeline has been largely emptied or the compressor has reached its physical operating limit. At this time, the control module immediately controls the variable frequency compressor to stop operating to prevent deep negative pressure or mechanical damage to the system. After the variable frequency compressor stops, the system enters the external refrigerant recovery stage. To ensure that the high-pressure refrigerant stored in the high-pressure side pipeline can be safely and smoothly transferred to external equipment, the control module must extract recovery status parameters and conduct a precise supply-demand matching assessment of the physical load-bearing capacity of the external receiving container and the load to be discharged on the high-pressure side. Specifically, this includes the following steps: The recovery pressure difference between the high-pressure side pipeline and the recovery storage tank is determined based on the pressure of the high-pressure side pipeline and the pressure of the recovery storage tank. Based on the high-pressure side pipeline pressure and the preset recovery termination pressure, determine the remaining pressure to be recovered, obtain the current converted temperature of the storage tank, and determine the receiving capacity of the storage tank based on the remaining capacity of the recovery storage tank and the current converted temperature of the storage tank. When the recovery pressure difference is greater than the preset recovery start pressure difference, and the storage tank receiving capacity meets the capacity requirement corresponding to the pressure to be recovered, the recovery control parameters are generated based on the recovery pressure difference, the pressure to be recovered, and the storage tank receiving capacity. The recovery control parameters include recovery device start parameters, target recovery power parameters, and recovery termination pressure parameters. The refrigerant recovery device is started based on the recovery device start parameters, and the refrigerant recovery device is controlled to recover the refrigerant in the high-pressure side pipeline through the recovery branch based on the target recovery power parameters; When the pressure in the high-pressure side pipeline is less than or equal to the pressure value corresponding to the recovery termination pressure parameter, the refrigerant recovery device is controlled to stop recovery.

[0092] After the variable frequency compressor stops operating, the high-pressure refrigerant accumulated in the high-pressure side pipeline needs to be safely transferred to an external refrigerant recovery unit. The transfer of fluid in the pipeline depends on the pressure gradient between the source and destination ends. To quantitatively assess the current physical driving force, the control module first extracts the high-pressure side pipeline pressure and the recovery tank pressure. The control module performs a subtraction operation in the underlying microprocessor, subtracting the recovery tank pressure from the high-pressure side pipeline pressure to calculate the recovery pressure difference between the high-pressure side pipeline and the recovery tank. The recovery pressure difference objectively characterizes the magnitude of the natural thermodynamic driving force for refrigerant to flow from the high-pressure side pipeline to the recovery tank. Accurately obtaining the recovery pressure difference helps the system determine whether the physical conditions for natural pressure difference drainage are met, and how much additional mechanical pressurization compensation the subsequent refrigerant recovery unit needs to provide. This avoids motor overload caused by starting the recovery unit when the pressure difference is too large, or refrigerant backflow when the pressure difference is insufficient.

[0093] After identifying the driving force, the control module needs to further assess the supply-demand matching between the load to be discharged on the high-pressure side and the actual receiving capacity of the recovery tank. The control module extracts the high-pressure side pipeline pressure and the preset recovery termination pressure. The preset recovery termination pressure is set based on the safe environmental pressure standard that the high-pressure side pipeline must reach before the refrigeration unit is repaired or scrapped, typically set to 0.1 MPa to 0.2 MPa (absolute pressure). The control module subtracts the preset recovery termination pressure from the high-pressure side pipeline pressure to calculate the remaining recovery pressure margin. This remaining recovery pressure margin quantifies the total refrigerant load that needs to be removed from the high-pressure side pipeline.

[0094] Meanwhile, the control module needs to assess the physical carrying capacity of the receiving end. Since the density of refrigerant gas is significantly affected by temperature, the physical volume alone cannot accurately reflect the true mass carrying capacity of the storage tank. Therefore, the control module obtains the current equivalent temperature of the storage tank. This equivalent temperature is derived from real-time values ​​collected by temperature sensors installed on the surface of the recovery tank, and after compensation for the tank wall thermal resistance using a low-level heat transfer algorithm, it objectively reflects the true thermodynamic environment temperature of the refrigerant inside the tank. The control module extracts the remaining capacity of the recovery tank and, combined with the current equivalent temperature, performs a thermodynamic state equation conversion to determine the tank's receiving margin. The specific conversion formula is: C_margin = V_remain * (T_std / T_current); In the formula, C_margin represents the tank receiving margin; V_remain represents the remaining capacity (physical volume) of the recovery tank; T_std represents the preset standard reference temperature (usually 293.15K, or 20℃); and T_current represents the current tank equivalent temperature (in Kelvin K). By introducing the current tank equivalent temperature for division correction, the system offsets the density decrease caused by refrigerant thermal expansion under high-temperature conditions. The calculated tank receiving margin represents the current, real, and safe effective receiving space of the recovery tank under the standard temperature reference. Through the aforementioned calculations, the system achieves accurate quantification of the load to be discharged and the actual receiving capacity, providing reliable data support for subsequent safe recovery operations.

[0095] Assuming the current high-pressure side pipeline pressure is 2.5 MPa, and the preset recovery termination pressure is set to 0.2 MPa, the control module calculates the remaining pressure to be recovered as 2.5 - 0.2 = 2.3 MPa. Simultaneously, the control module reads the remaining capacity of the recovery tank as 10.0 L. The sensor collects and converts the current tank temperature to 313.15 K (i.e., 40°C). The preset standard reference temperature is 293.15 K. The control module substitutes these values ​​into the formula to calculate the tank receiving margin as 10.0 * (293.15 / 313.15) ≈ 9.36 L. This value of 9.36 L indicates that due to the current high temperature of 40°C, the gas inside the tank expands, and the original physical remaining space of 10.0 L is reduced to a calculated effective receiving margin of only 9.36 L. The control module will then use the 2.3 MPa remaining pressure to be recovered and the 9.36 L tank receiving margin to perform subsequent supply and demand matching judgments.

[0096] During the continuous evacuation and compression operation of the variable frequency compressor, the control module needs to monitor the thermodynamic state of the system and the physical load of the underlying hardware in real time to accurately determine the termination point of the evacuation operation. The control module first compares the real-time collected low-pressure side pipeline pressure with the preset evacuation threshold written in the underlying memory. The preset evacuation threshold is set based on the physical standard for the low-pressure side of the refrigeration system to reach a safe evacuation state. To prevent the system from entering a deep negative pressure state, causing external air to be drawn back into the pipeline through tiny gaps, the preset evacuation threshold is typically set to 0.02 MPa to 0.05 MPa (absolute pressure). When the comparison result shows that the low-pressure side pipeline pressure is less than or equal to the preset evacuation threshold, it indicates that the refrigerant in the low-pressure side pipeline and inside the evaporator has been sufficiently evacuated and transferred to the high-pressure side. Continuing to run the variable frequency compressor will not only fail to produce effective displacement but will also waste electrical energy and exacerbate mechanical wear.

[0097] Meanwhile, as the low-pressure side pressure continues to decrease, the refrigerant mass flow rate entering the variable frequency compressor drops sharply, causing the compressor to lose the physical condition of self-cooling by drawing in refrigerant. To prevent irreversible physical damage to the variable frequency compressor under extreme operating conditions, the control module evaluates in parallel whether the compressor meets the preset evacuation stop conditions. The preset evacuation stop conditions cover the safe operating limits of the compressor's underlying hardware, specifically including: exhaust temperature exceeding the preset temperature limit (usually set to 105°C to 115°C to prevent high-temperature carbonization failure of the internal lubricating oil); drive current exceeding the preset overload limit (usually set to 110% to 120% of the rated current to prevent burnout of the motor winding insulation); or continuous evacuation time exceeding the preset timeout threshold (usually set to 10 to 15 minutes to prevent prolonged dry friction of the scroll plate).

[0098] When the low-pressure side pipeline pressure is less than or equal to the preset evacuation threshold, or when the variable frequency compressor meets any of the preset evacuation stop conditions (i.e., satisfies the logical "OR" relationship), the control module immediately triggers the shutdown protection logic. The control module sends a zero-speed command to the inverter of the variable frequency compressor or directly cuts off the pulse width modulation drive signal, forcibly controlling the variable frequency compressor to stop running. Through the aforementioned dual shutdown judgment mechanism based on the achievement of the evacuation target and the underlying hardware protection, the system can maximize the emptying of refrigerant in the leakage danger zone while ensuring that the variable frequency compressor is protected from damage by deep negative pressure and thermodynamic overload, and smoothly transition the system from the dynamic suction stage to the static pressure holding stage, laying a safe physical foundation for the subsequent transfer of high-pressure side refrigerant to the outside.

[0099] After both dynamics and space safety verifications have passed, confirming that the system fully meets the physical prerequisites for safe recovery, the control module must convert macroscopic physical state parameters into low-level control commands to guide external equipment in executing specific actions. To ensure that the recovery operation does not generate destructive fluid shocks at startup, achieves a dynamic balance between suction efficiency and tank capacity during continuous operation, and balances the thoroughness of refrigerant extraction with the final safety boundary of the receiving container at the end of the operation, the control module cannot output a fixed, unchanging single command. The control module must extract the recovery pressure differential, the remaining pressure margin to be recovered, and the tank receiving margin as core input variables, and perform multi-dimensional decoupling calculations and fine-tuning configurations for startup mode, operating power, and shutdown thresholds, thereby generating a comprehensive control strategy highly matched to the current operating conditions. This includes the following steps.

[0100] When the recovery pressure difference is greater than the preset impact pressure difference threshold, the start-up parameters of the recovery device are configured to a preset soft-start mode; When the recovery pressure difference is less than or equal to the preset impact pressure difference threshold, the start-up parameters of the recovery device are configured to a preset direct start-up mode; The basic recovery power parameters are determined based on the pressure margin to be recovered, and the basic recovery power parameters are positively correlated with the pressure margin to be recovered. A power correction coefficient is determined based on the receiving margin of the storage tank, and the power correction coefficient is positively correlated with the receiving margin of the storage tank; The product of the basic recovery power parameter and the power correction coefficient is determined as the target recovery power parameter; The termination pressure compensation amount is determined based on the tank receiving margin, and the termination pressure compensation amount is negatively correlated with the tank receiving margin. The preset recovery termination pressure is superimposed with the termination pressure compensation amount to obtain the recovery termination pressure parameter.

[0101] After confirming that the system possesses the physical prerequisites for safe refrigerant recovery, the control module first needs to formulate a safety strategy for the initial startup phase of the recovery operation to prevent the instantaneously established fluid channel from causing destructive mechanical impacts on external equipment. The control module extracts the previously calculated recovery pressure difference and compares it with a preset impact pressure difference threshold written in the underlying memory. The preset impact pressure difference threshold is set based on the maximum transient fluid impact intensity that the compressor valves and pipe joints inside the refrigerant recovery unit can withstand, typically set to 1.0 MPa to 1.5 MPa. When the comparison result shows that the recovery pressure difference is greater than the preset impact pressure difference threshold, it indicates that the initial pressure gradient between the high-pressure side pipeline and the recovery tank is too large. If the external equipment is started at full speed at this time, the high-pressure refrigerant will rush into the recovery unit at an extremely high flow rate, easily causing liquid slugging or causing the motor rotor to stall due to excessive initial load. Therefore, the control module configures the recovery unit's startup parameters to a preset soft-start mode. The preset soft-start mode instructs the inverter of the recovery unit to slowly increase the output frequency at a very low acceleration, while simultaneously controlling the bypass unloading valve inside the recovery unit to be open, thereby actively reducing mechanical stress and fluid impact during the initial startup phase. Conversely, when the comparison results show that the recovery pressure difference is less than or equal to the preset impact pressure difference threshold, it indicates that the initial pressure gradient is within the safe tolerance range of the equipment hardware. To shorten the overall recovery operation time and improve work efficiency, the control module configures the recovery unit's startup parameters to a preset direct-start mode. The preset direct-start mode allows the recovery unit to quickly establish suction power directly at the rated frequency or target frequency after the start relay is closed, without needing to perform a slow frequency ramp-up process.

[0102] For example, suppose the preset impact pressure difference threshold is set to 1.2 MPa. If the currently calculated recovery pressure difference is 1.8 MPa, the control module determines that 1.8 MPa is greater than 1.2 MPa, indicating a risk of fluid impact. It then configures the recovery device's startup parameters to a preset soft-start mode, controlling the recovery device to slowly increase its speed to operating status over 15 seconds. If the current recovery pressure difference is 0.8 MPa, the control module determines that 0.8 MPa is less than 1.2 MPa, and then configures it to a preset direct-start mode, controlling the recovery device to quickly reach the target speed within 2 seconds.

[0103] When determining the basic recovery power parameters, the control module needs to establish a dynamic matching relationship between the mechanical suction power and the load of the fluid to be processed. The pressure margin to be recovered objectively quantifies the mass of refrigerant accumulated in the high-pressure side pipeline. To accurately define the physical magnitude of the load, the control module introduces a preset rated pressure margin as a benchmark. The preset rated pressure margin is set based on the typical high-low pressure difference peak value of the refrigeration system under full load operation under standard conditions, usually set to 2.5MPa to 3.0MPa. When the pressure margin to be recovered approaches or exceeds the preset rated pressure margin, it objectively indicates that the current state is high-load, and the system needs to output maximum safe power to quickly reduce pipeline pressure and shorten operation time; conversely, when the pressure margin to be recovered is significantly lower than the preset rated pressure margin and approaches zero, it indicates a low-load state, and reducing the output power can effectively reduce motor energy consumption and mechanical wear. Based on the above physical logic, the algorithm stipulates that the basic recovery power parameter is positively correlated with the pressure margin to be recovered. In practice, the control module calls the preset power conversion coefficient (set based on compressor displacement characteristics, typically 20Hz / MPa to 30Hz / MPa) and preset minimum operating frequency (used to maintain basic motor operation and lubricating oil circulation, typically 15Hz to 20Hz) stored at the underlying level. The control module calculates the basic recovered power parameters using a linear mapping formula with upper and lower limit functions. The specific calculation formula is: Freq_base=MIN(Freq_max,MAX(Freq_min,(K_freq*P_margin)+Freq_min)); In the formula, Freq_base represents the basic recovered power parameters; MIN is the minimum value function used to perform upper limit protection; MAX is the maximum value function used to perform lower limit protection; Freq_max represents the preset maximum operating frequency (limited by motor insulation and bearing strength, typically 80Hz to 90Hz); K_freq represents the preset power conversion coefficient; P_margin represents the pressure margin to be recovered; and Freq_min represents the preset minimum operating frequency.

[0104] For example: Assume the preset maximum operating frequency is set to 85Hz, the preset minimum operating frequency is set to 15Hz, and the preset power conversion factor is set to 25Hz / MPa. If the current pressure margin to be recovered is 2.0MPa, the control module calculates the initial frequency using the formula as (25*2.0)+15=65Hz. Since 65Hz is within the safe range, the control module determines the basic recovery power parameter to be 65Hz.

[0105] After obtaining the basic recovery power parameters, the control module must introduce the physical constraints at the destination. The tank receiving margin reflects the physical leeway of the external receiving container. When the tank receiving margin is sufficient, the system can safely pressurize the fluid at the calculated basic power; however, when the tank receiving margin approaches its physical limit, continuing to pressurize at high power can easily cause a sudden surge in internal pressure, triggering the safety valve or even causing the container to burst. Therefore, the pressurization rate must be forcibly reduced when space is limited. Based on this safety constraint, the algorithm stipulates that the power correction coefficient is positively correlated with the tank receiving margin; that is, the smaller the margin, the closer the generated correction coefficient is to zero, and the stronger the power reduction effect. In specific implementation, the control module extracts a preset safety capacity threshold (representing the critical space size for triggering frequency reduction protection, usually set to 20% to 30% of the total tank volume). The control module divides the tank receiving margin by the preset safety capacity threshold to obtain the initial ratio. To prevent the motor from stopping due to the correction coefficient exceeding its limit, the control module performs extreme value limiting processing on the initial ratio, with a maximum of 1.0 and a minimum of 0.1. The final output value is the power correction coefficient. The specific calculation formula is: C_power=MIN(1.0,MAX(0.1,V_margin / V_safe)); where C_power represents the power correction coefficient; V_margin represents the tank's receiving margin; and V_safe represents the preset safe capacity threshold. After obtaining the above two parameters, the control module performs a multiplication operation, multiplying the basic recovered power parameter by the power correction coefficient. The calculated product is the target recovered power parameter. Through the aforementioned decoupled calculation and multiplication coupling, the generated power command satisfies both the rapid emptying requirement of the source end and strictly adheres to the capacity safety constraints of the destination end. For example: assuming the preset safe capacity threshold is set to 10.0L. If the current tank receiving margin is 6.0L, the control module calculates the ratio as 6.0 / 10.0=0.6. After amplitude limiting, the power correction factor was determined to be 0.6. The control module then multiplied the previously calculated 65Hz baseline recoverable power parameter by 0.6 to obtain the final target recoverable power parameter of 39Hz. The recovery device will then operate smoothly at a reduced frequency of 39Hz.

[0106] Finally, the control module needs to intervene proactively at the termination point of the refrigerant recovery operation to ensure safety. The system's default preset recovery termination pressure is usually set to a low fixed value (e.g., 0.1MPa to 0.15MPa) to maximize refrigerant extraction. However, when the tank's receiving margin is extremely low, forcibly extracting to an extremely low termination pressure will inevitably force refrigerant exceeding the tank's capacity into the container, leading to a serious safety accident. Therefore, when space is insufficient, the system must proactively abandon the pursuit of ultimate vacuum and terminate the recovery operation early. This requires that the smaller the margin, the larger the compensation value added to the preset recovery termination pressure must be, thus significantly raising the shutdown threshold. Based on this logic, the algorithm stipulates that the termination pressure compensation is negatively correlated with the tank's receiving margin. In specific implementation, the control module determines whether the tank's receiving margin is less than the preset safety capacity threshold. If it is greater than or equal to, the control module directly assigns the termination pressure compensation value to zero. If the value is less than the preset safe capacity threshold, the control module calculates the capacity difference between the preset safe capacity threshold and the tank's receiving margin, and multiplies this difference by a preset pressure compensation coefficient (set based on the tank's pressure-volume change rate, typically 0.05 MPa / L to 0.1 MPa / L) to calculate the termination pressure compensation amount. The specific calculation formula is: P_comp = K_comp * MAX(0, (V_safe - V_margin)); where P_comp represents the termination pressure compensation amount; K_comp represents the preset pressure compensation coefficient; and the MAX function ensures the compensation amount is not negative. After calculation, the control module adds the preset recovery termination pressure to the termination pressure compensation amount, and the resulting value is the recovery termination pressure parameter. Through this negative correlation compensation mechanism, the system achieves the control objective of sacrificing some recovery thoroughness in exchange for absolute physical safety.

[0107] For example: Assume the preset recovery termination pressure is set to 0.15 MPa, the preset safety capacity threshold is 10.0 L, and the preset pressure compensation coefficient is set to 0.08 MPa / L. If the current tank receiving capacity is 5.0 L, the control module determines that 5.0 L is less than 10.0 L and triggers the compensation mechanism. The control module calculates the capacity difference as 10.0 - 5.0 = 5.0 L. Multiplying 5.0 L by 0.08 MPa / L, the termination pressure compensation is determined to be 0.4 MPa. The control module adds 0.15 MPa and 0.4 MPa to obtain a recovery termination pressure parameter of 0.55 MPa. When the pressure in the high-pressure side pipeline drops to 0.55 MPa, the system will control the recovery device to stop operating in advance.

[0108] After the control module completes the decoupling calculation and generation of all underlying control parameters, the system must convert the digitized logic instructions into electrical signals that drive the external hardware to perform physical actions, thus formally initiating the refrigerant transfer operation. The control module first extracts the generated recovery unit start-up parameters. These parameters determine the initial excitation and acceleration strategy of the external compressor motor at the moment of power-on. The control module sends the corresponding trigger command to the inverter of the refrigerant recovery unit via the underlying communication bus. If the recovery unit start-up parameters are configured for a preset soft-start mode, the control module instructs the inverter to slowly increase the output voltage and frequency from zero with a very low fixed acceleration, according to a preset voltage-to-frequency ratio (V / F curve). The slowly increasing electromagnetic torque allows the motor rotor to smoothly overcome static friction, effectively avoiding the impact of the huge surge current generated by instantaneous full-pressure start-up on the power grid, and also preventing the high-pressure refrigerant from instantly rushing into the recovery branch at high speed and causing destructive fluid slugging. If the recovery unit start-up parameters are configured for a preset direct-start mode, the control module instructs the inverter or main contactor to close rapidly, allowing the motor to reach its basic operating speed in a very short time.

[0109] After the motor starts and establishes initial suction power, the control module simultaneously opens the solenoid valve on the recovery branch, opening the fluid channel between the high-pressure side pipeline and the external container. Subsequently, the control module extracts the target recovery power parameter. This target recovery power parameter, serving as a continuous speed control command during steady-state operation, directly determines the refrigerant extraction rate. The control module converts the target recovery power parameter into a pulse-width modulation (PWM) signal duty cycle command and sends it to the external inverter. Based on the received duty cycle command, the inverter precisely adjusts the frequency of the three-phase AC power output to the compressor motor, forcing the refrigerant recovery device to operate continuously at the speed corresponding to the target recovery power parameter. By strictly executing the above start-up and power adjustment commands, the system ensures that the mechanical equipment intervenes safely and, at the optimal rate dynamically matched to the current available space, smoothly delivers the refrigerant from the high-pressure side pipeline to the recovery storage tank.

[0110] For example: Assume the pre-calculated startup parameters for the refrigerant recovery device are a preset soft-start mode, and the target recovery power parameter is 39Hz. The control module first sends a soft-start command to the external inverter, controlling the inverter to linearly and smoothly increase the drive frequency from 0Hz to 15Hz within 15 seconds (15Hz is the minimum safe frequency to maintain motor operation). After the 15-second soft-start process, the motor runs smoothly, and the initial pressure difference shock in the fluid channel is effectively resolved. The control module then sends a new frequency adjustment command, controlling the inverter to increase the output frequency and lock it at 39Hz. The refrigerant recovery device, in its 39Hz frequency reduction state, continuously draws refrigerant from the high-pressure side pipeline through the recovery branch.

[0111] During the continuous operation of the refrigerant recovery unit, the refrigerant mass inside the high-pressure side pipeline continuously decreases, macroscopically manifested as a continuous drop in pipeline pressure. To prevent the external compressor from entering a deep vacuum state after the pipeline is emptied, which could lead to mechanical dry friction, and to strictly adhere to the safety capacity baseline of the external receiving container, the control module must perform high-frequency real-time monitoring of the termination point of the recovery operation. The control module continuously acquires the high-pressure side pipeline pressure at a millisecond-level sampling period through a pressure transmitter installed on the high-pressure side pipeline. The control module inputs the real-time high-pressure side pipeline pressure and the dynamically generated recovery termination pressure parameter from the previous stage into the underlying comparator logic for numerical comparison.

[0112] The recovery termination pressure parameter represents a dynamic shutdown threshold derived by comprehensively considering the thoroughness of extraction and the explosion-proof safety of the storage tank. When the comparison result shows that the pressure in the high-pressure side pipeline is greater than the pressure value corresponding to the recovery termination pressure parameter, it indicates that there is still a refrigerant load that can be safely transferred in the pipeline, and the control module maintains the inverter's drive signal output. When the pressure in the high-pressure side pipeline continues to drop until it is less than or equal to the pressure value corresponding to the recovery termination pressure parameter, the objective physical state indicates that either the refrigerant in the high-pressure side pipeline has been evacuated to the maximum extent, or the total amount of refrigerant compressed to the external storage tank has approached the physical capacity limit of the storage tank. At the instant the condition is met, the control module immediately triggers the highest priority shutdown interruption procedure. The control module sends a zero-speed command to the inverter to cut off the motor drive power supply and simultaneously cuts off the holding current of the solenoid valve in the recovery branch, using a spring reset mechanical structure to instantly cut off the fluid passage. By executing precise shutdown logic, the system completely isolates the internal and external pipelines, successfully avoiding the risk of air backflow and storage tank overload explosion, and realizing a safe closed loop for the entire refrigerant recovery operation.

[0113] For example: Assume the calculated recovery termination pressure parameter, based on the remaining space in the storage tank, is 0.55 MPa. During the recovery operation, the control module continuously reads the pressure transmitter data. When the high-pressure side pipeline pressure gradually decreases from 2.0 MPa to 0.60 MPa, the control module determines that 0.60 MPa is greater than 0.55 MPa, and the system continues to maintain a 39Hz suction operation. When the sensor reading further decreases and reaches 0.55 MPa, the control module determines that the termination condition has been met. The control module immediately sends a shutdown command to the inverter and closes the solenoid valve of the recovery branch. The refrigerant recovery unit stops operating, the high-pressure side pipeline pressure is safely locked at 0.55 MPa, and the recovery operation ends.

[0114] Please see Figure 3 This is a schematic diagram of the structure of an intelligent and environmentally friendly refrigeration control system in an embodiment of this application.

[0115] It should be noted that, Figure 3The structure of the intelligent and environmentally friendly refrigeration control system shown is merely an example and should not impose any limitations on the functionality and scope of application of the embodiments of the present invention.

[0116] like Figure 3 As shown, an intelligent and environmentally friendly refrigeration control system includes a central processing unit 301, which can perform various appropriate actions and processes according to a program stored in a read-only memory 302 or a program loaded from a storage section 308 into a random access memory 303, such as executing the methods described in the above embodiments. The random access memory 303 also stores various programs and data required for system operation. The central processing unit 301, the read-only memory 302, and the random access memory 303 are interconnected via a bus 304. An input / output interface 305 is also connected to the bus 304.

[0117] The following components are connected to the input / output interface 305: an input section 306 including audio input devices, push-button switches, etc.; an output section 307 including an LCD display, audio output devices, indicator lights, etc.; a storage section 308 including a hard disk, etc.; and a communication section 309 including a network interface card such as a LAN (Local Area Network) card, modem, etc. The communication section 309 performs communication processing via a network such as the Internet. A drive 310 is also connected to the input / output interface 305 as needed. A removable medium 311, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on the drive 310 as needed so that computer programs read from it can be installed into the storage section 308 as needed.

[0118] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing computer programs for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication section 309, and / or installed from removable medium 311. When the computer program is executed by central processing unit 301, it performs the various functions defined in the present invention.

[0119] It should be noted that specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory, read-only memory, erasable programmable read-only memory, flash memory, optical fiber, portable compact disk read-only memory, optical storage devices, magnetic storage devices, or any suitable combination thereof. In this invention, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0120] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. Each block in a flowchart or block diagram may represent a module, segment, or portion of code, which contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those shown in the drawings.

[0121] Specifically, an intelligent and environmentally friendly refrigeration control system according to this embodiment includes a processor and a memory. The memory stores a computer program. When the computer program is executed by the processor, it implements an intelligent and environmentally friendly refrigeration control method provided in the above embodiment.

[0122] In another aspect, the present invention also provides a computer-readable storage medium, which may be included in the intelligent and environmentally friendly refrigeration control system described in the above embodiments; or it may exist independently and not assembled into the intelligent and environmentally friendly refrigeration control system. The storage medium carries one or more computer programs, which, when executed by a processor of the intelligent and environmentally friendly refrigeration control system, cause the intelligent and environmentally friendly refrigeration control system to implement the intelligent and environmentally friendly refrigeration control method provided in the above embodiments.

Claims

1. An intelligent and environmentally friendly refrigeration control method, characterized in that, The method is applied to a refrigeration device, which includes a refrigeration cycle loop and a monitoring module, a control module, and a refrigerant recovery device connected to the refrigeration cycle loop. The refrigeration cycle loop includes a variable frequency compressor, a condenser, an electronic expansion valve, a liquid supply valve, an evaporator, a low-pressure side pipeline, and a high-pressure side pipeline. The liquid supply valve is located on the high-pressure side pipeline between the condenser and the electronic expansion valve. The refrigerant recovery device is connected to the high-pressure side pipeline through a recovery branch. The method includes: The monitoring module acquires operating status parameters, refrigerant leakage concentration, and recovery status parameters, including low-pressure side pipeline pressure. When the refrigerant leakage concentration is less than a preset safety threshold, cooling power adjustment parameters are generated based on the operating status parameters, and the speed of the variable frequency compressor and the opening of the electronic expansion valve are adjusted according to the cooling power adjustment parameters. When the refrigerant leakage concentration is greater than or equal to the preset safety threshold, the liquid supply valve is controlled to close, and the electronic expansion valve is controlled to maintain the preset evacuation opening, so that the pipe section between the liquid supply valve and the electronic expansion valve is connected to the low-pressure side pipe through the electronic expansion valve, the evaporator and the low-pressure side pipe, forming an evacuation channel connected to the suction end of the variable frequency compressor. The evacuation status is evaluated based on the operating status parameters to obtain evacuation status parameters. Based on the evacuation status parameters, the target evacuation speed is determined, and the variable frequency compressor is controlled to operate at the target evacuation speed to pressurize the refrigerant in the evacuation channel to the high-pressure side pipeline. When the pressure in the low-pressure side pipeline is less than or equal to the preset evacuation threshold, or when the variable frequency compressor meets the preset evacuation stop condition, the control module controls the variable frequency compressor to stop running, and generates recovery control parameters based on the recovery status parameters. Based on the recovery control parameters, the refrigerant recovery device is controlled to recover the refrigerant in the high-pressure side pipeline through the recovery branch.

2. The method according to claim 1, characterized in that, The operating status parameters also include the evaporator outlet temperature and the actual refrigerated space temperature. The process of generating refrigeration power adjustment parameters based on these operating status parameters, and adjusting the speed of the variable frequency compressor and the opening of the electronic expansion valve according to these refrigeration power adjustment parameters, specifically includes: Obtain the target cooling temperature, calculate the temperature deviation between the actual cooling space temperature and the target cooling temperature, and determine the target compressor speed based on the temperature deviation. Based on the low-pressure side pipeline pressure and the preset refrigerant pressure-saturation temperature mapping relationship, the evaporation saturation temperature is determined, and the difference between the evaporator outlet temperature and the evaporation saturation temperature is calculated to obtain the actual superheat. Calculate the superheat deviation between the actual superheat and the preset target superheat, and determine the expansion valve feedforward compensation amount based on the target compressor speed; The target expansion valve opening is determined based on the superheat deviation and the expansion valve feedforward compensation, and the target compressor speed and the target expansion valve opening are used as the refrigeration power adjustment parameters. The variable frequency compressor is controlled to operate according to the target compressor speed, and the electronic expansion valve is controlled to adjust its opening according to the target expansion valve opening.

3. The method according to claim 2, characterized in that, The determination of the expansion valve feedforward compensation amount based on the target compressor speed specifically includes: Obtain the current compressor speed and calculate the speed change between the target compressor speed and the current compressor speed; The low-pressure safety margin is determined based on the difference between the low-pressure side pipeline pressure and the preset low-pressure protection threshold, wherein the preset low-pressure protection threshold is greater than the preset evacuation threshold. The current heat load coefficient is determined based on the temperature deviation value. The dynamic feedforward gain coefficient is determined based on the low-pressure safety margin and the current heat load coefficient. When the speed change is greater than zero, the dynamic feedforward gain coefficient is negatively correlated with the low-pressure safety margin and positively correlated with the current heat load coefficient. The product of the speed change and the preset basic feedforward coefficient is determined as the basic opening compensation amount; The initial feedforward compensation amount is obtained by performing gain correction on the basic opening compensation amount based on the dynamic feedforward gain coefficient. The initial feedforward compensation amount is limited according to the preset upper limit and lower limit of the opening compensation to obtain the feedforward compensation amount of the expansion valve.

4. The method according to claim 1, characterized in that, The operating status parameters also include the high-pressure side pipeline pressure. The process of evaluating the evacuation status based on these operating status parameters to obtain evacuation status parameters, and determining the target evacuation speed based on these evacuation status parameters, specifically includes: The rate of decrease in low-pressure side pipeline pressure and the rate of increase in refrigerant leakage concentration are determined based on the decrease in low-pressure side pipeline pressure within a preset time window and the increase in refrigerant leakage concentration within the preset time window, respectively. The rate of decrease in low-pressure side pressure and the rate of increase in leakage concentration are used as the evacuation state parameters, and the basic evacuation speed is determined based on the rate of increase in leakage concentration, wherein the basic evacuation speed is positively correlated with the rate of increase in leakage concentration. Calculate the rate deviation between the low-pressure side pressure drop rate and the preset target drop rate, and determine the evacuation speed compensation amount based on the rate deviation; The sum of the base evacuation speed and the evacuation speed compensation amount is determined as the initial evacuation speed; The real-time compression ratio is determined based on the pressure in the high-pressure side pipeline and the pressure in the low-pressure side pipeline, and the initial evacuation speed is subjected to safety limiting processing based on the real-time compression ratio to obtain the target evacuation speed.

5. The method according to claim 4, characterized in that, The step of performing a safety limiting process on the initial evacuation speed based on the real-time compression ratio to obtain the target evacuation speed specifically includes: The real-time compression ratio is compared with a preset compression ratio safety threshold. When the real-time compression ratio is less than or equal to the preset compression ratio safety threshold, the initial evacuation speed is limited based on the preset upper limit and lower limit of the evacuation speed to obtain the target evacuation speed. When the real-time compression ratio is greater than the preset compression ratio safety threshold, a frequency reduction and limiting coefficient is determined based on the over-limit difference between the real-time compression ratio and the preset compression ratio safety threshold. The frequency reduction and limiting coefficient is greater than zero and less than one, and the frequency reduction and limiting coefficient is negatively correlated with the over-limit difference. Based on the frequency reduction and amplitude limiting coefficient, the initial evacuation speed is corrected by frequency reduction to obtain the corrected evacuation speed; The target evacuation speed is obtained by limiting the modified evacuation speed based on the preset upper limit and the preset lower limit of the evacuation speed.

6. The method according to claim 1, characterized in that, The recovery status parameters include the recovery tank pressure and the remaining capacity of the recovery tank. The generation of recovery control parameters based on the recovery status parameters, and the control of the refrigerant recovery device to recover refrigerant from the high-pressure side pipeline via the recovery branch based on the recovery control parameters, specifically includes: The recovery pressure difference between the high-pressure side pipeline and the recovery storage tank is determined based on the pressure of the high-pressure side pipeline and the pressure of the recovery storage tank. Based on the high-pressure side pipeline pressure and the preset recovery termination pressure, determine the remaining pressure to be recovered, obtain the current converted temperature of the storage tank, and determine the receiving capacity of the storage tank based on the remaining capacity of the recovery storage tank and the current converted temperature of the storage tank. When the recovery pressure difference is greater than the preset recovery start pressure difference, and the storage tank receiving capacity meets the capacity requirement corresponding to the pressure to be recovered, the recovery control parameters are generated based on the recovery pressure difference, the pressure to be recovered, and the storage tank receiving capacity. The recovery control parameters include recovery device start parameters, target recovery power parameters, and recovery termination pressure parameters. The refrigerant recovery device is started based on the recovery device start parameters, and the refrigerant recovery device is controlled to recover the refrigerant in the high-pressure side pipeline through the recovery branch based on the target recovery power parameters; When the pressure in the high-pressure side pipeline is less than or equal to the pressure value corresponding to the recovery termination pressure parameter, the refrigerant recovery device is controlled to stop recovery.

7. The method according to claim 6, characterized in that, The process of generating the recovery control parameters based on the recovery pressure differential, the remaining pressure to be recovered, and the receiving capacity of the storage tank specifically includes: When the recovery pressure difference is greater than the preset impact pressure difference threshold, the start-up parameters of the recovery device are configured to a preset soft-start mode; When the recovery pressure difference is less than or equal to the preset impact pressure difference threshold, the start-up parameters of the recovery device are configured to a preset direct start-up mode; The basic recovery power parameters are determined based on the pressure margin to be recovered, and the basic recovery power parameters are positively correlated with the pressure margin to be recovered. A power correction coefficient is determined based on the receiving margin of the storage tank, and the power correction coefficient is positively correlated with the receiving margin of the storage tank; The product of the basic recovery power parameter and the power correction coefficient is determined as the target recovery power parameter; The termination pressure compensation amount is determined based on the tank receiving margin, and the termination pressure compensation amount is negatively correlated with the tank receiving margin. The preset recovery termination pressure is superimposed with the termination pressure compensation amount to obtain the recovery termination pressure parameter.

8. An intelligent and environmentally friendly refrigeration control system, characterized in that, The intelligent and environmentally friendly refrigeration control system includes: one or more processors and a memory; the memory is coupled to the one or more processors, the memory is used to store computer program code, the computer program code includes computer instructions, and the one or more processors call the computer instructions to cause the intelligent and environmentally friendly refrigeration control system to perform the method as described in any one of claims 1-7.

9. A computer-readable storage medium comprising instructions, characterized in that, When the instruction is executed on the intelligent environmentally friendly refrigeration control system, the intelligent environmentally friendly refrigeration control system performs the method as described in any one of claims 1-7.

10. A computer program product, characterized in that, When the computer program product is run on the intelligent environmentally friendly refrigeration control system, the intelligent environmentally friendly refrigeration control system performs the method as described in any one of claims 1-7.

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