Intelligent control method and system for heat pump in ultra-low temperature environment

Abstract

This invention proposes a smart control method and system for heat pumps in ultra-low temperature environments. The method includes: acquiring the heat pump operating status, including suction superheat, system pressure ratio, and compressor frequency; when the compressor frequency is stable, executing an electronic expansion valve detection action and recording the valve detection response data; calculating the evaporator comprehensive response coefficient based on the response data and classifying the evaporator response state; and finally, synchronously generating coordinated control commands for the electronic expansion valve and compressor based on this state. This invention, by actively detecting the dynamic response capability of the evaporator, distinguishes between actual liquid supply demand and ultra-low temperature thermal inertia, achieving coordinated valve-machine control. It effectively solves the problems of control oscillations, excessively high exhaust temperatures, and liquid slugging risks that easily occur in heat pump systems under ultra-low temperature environments, significantly improving operational stability and heating efficiency under specific operating conditions.

Description

Technical Field

[0001] This invention belongs to the field of heat pump technology, and particularly relates to a smart control method and system for heat pumps used in ultra-low temperature environments. Background Technology

[0002] When air source heat pumps operate in low-temperature and ultra-low-temperature regions for heating, the refrigerant circulation volume needs to be jointly regulated by a variable frequency compressor and an electronic expansion valve to maintain a balance between the evaporator's heat absorption capacity, the condenser's heat release capacity, and the compressor's safe operation. Existing units typically use suction superheat as the basis for adjusting the electronic expansion valve opening, and ambient temperature, outlet water temperature, or load demand as the basis for compressor frequency adjustment, combined with system pressure ratio, discharge temperature, and other parameters for protection correction. This type of solution can meet basic control requirements under normal low-temperature conditions, but when the ambient temperature drops to around -25℃ to -40℃, the evaporator's heat exchange capacity decreases significantly, cold storage in the fins and pipes intensifies, and the combined effects of low evaporation pressure, high pressure ratio, increased discharge temperature, and frosting cause the system to exhibit strong hysteresis and coupling. Under this operating condition, although the suction superheat reflects the refrigerant state at the compressor inlet, its changes often lag behind the action of the electronic expansion valve and the actual heat exchange recovery process of the evaporator. The same phenomenon of high suction superheat may correspond to different causes such as insufficient liquid supply, severe cold storage in the evaporator, slow heat exchange recovery, or changes in the compressor circulation volume. If the controller directly increases the opening of the electronic expansion valve based on the current suction superheat, it is easy to cause subsequent liquid supply overshoot before the evaporator has sufficient heat absorption capacity. If the compressor simultaneously increases its frequency according to load demand, it will further change the evaporation pressure and system pressure ratio, making it difficult to accurately judge the response of the electronic expansion valve action, which may lead to control oscillation, increased exhaust temperature, fluctuations in heating capacity, or even the risk of liquid refrigerant entering the compressor. Therefore, existing control methods based on fixed target superheat, single suction superheat adjustment, or simple dual-parameter correction lack the ability to identify the true dynamic response of the evaporator after a small action of the electronic expansion valve, making it difficult to determine whether the evaporator has the ability to continue receiving liquid supply and increase circulation volume. This is precisely the key engineering problem that needs to be improved in the valve-machine coordinated control of ultra-low temperature heat pumps. Especially in scenarios such as before and after defrosting, changes in the frost layer on the outdoor heat exchanger, compressor frequency increase transition, and auxiliary electric heating switching, the suction superheat, evaporation pressure, and exhaust temperature may change simultaneously. If the detection conditions and execution boundaries are not limited, the protection process or transition process may be mistaken for the evaporator's true response capability. Summary of the Invention

[0003] This invention discloses a smart control method and system for heat pumps in ultra-low temperature environments, in order to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the first aspect of the present invention provides a smart control method for heat pumps in ultra-low temperature environments, the method comprising: Acquire heat pump operating status data, which includes suction superheat, system pressure ratio, exhaust temperature, current opening of electronic expansion valve, and current compressor frequency; When the compressor's current frequency is stable, an electronic expansion valve detection action is generated based on the heat pump's operating status data, and the heat pump's operating status data before and after the detection is recorded to form valve detection response data; The comprehensive response coefficient of the evaporator is calculated based on the valve detection response data, and the evaporator response state is classified based on the comprehensive response coefficient of the evaporator. Based on the evaporator response status, the target opening degree of the electronic expansion valve and the target frequency of the compressor are generated synchronously, and the electronic expansion valve and the compressor are controlled to operate.

[0005] Furthermore, acquiring the heat pump operating status data includes: Read the intake temperature, evaporation pressure, condensation pressure, and exhaust temperature within a fixed control cycle; The intake superheat is calculated based on the saturation temperature corresponding to the intake temperature and the evaporation pressure. The system pressure ratio is calculated based on the ratio of the condensation pressure to the evaporation pressure.

[0006] Furthermore, the step of generating an electronic expansion valve detection action based on the heat pump operating status data when the compressor's current frequency is stable includes: The detection intensity coefficient is calculated based on the intake superheat, system pressure ratio, exhaust temperature, and current opening of the electronic expansion valve. The change in the electronic expansion valve's detection opening is determined based on the detection intensity coefficient and the intake superheat. While keeping the compressor's current frequency constant, the electronic expansion valve is controlled to perform the action of detecting changes in its opening degree.

[0007] Furthermore, the recorded heat pump operating status data before and after the detection includes: Before the electronic expansion valve performs the detection action, record the intake superheat, evaporation pressure, and system pressure ratio before detection. After the electronic expansion valve performs the detection action and maintains it for a preset time, record the intake superheat, evaporation pressure, and system pressure ratio after detection.

[0008] Further, the calculation of the evaporator comprehensive response coefficient based on the valve detection response data includes: The effective recovery term is calculated based on the difference between the inhalation superheat before and after detection, and the ratio of the change in evaporation pressure before and after detection. The suppression term is calculated based on the change in system pressure ratio after detection compared to before detection, and the current frequency of the compressor. The overall response coefficient of the evaporator is determined based on the ratio of the effective recovery term to the suppression term.

[0009] Furthermore, the step of classifying the evaporator response state based on the evaporator comprehensive response coefficient includes: The overall response coefficient of the evaporator is compared with the preset normal response threshold and insufficient recovery threshold; When the overall response coefficient of the evaporator is greater than the normal response threshold, the evaporator response status is determined to be normal. When the overall response coefficient of the evaporator is less than the insufficient recovery threshold, the evaporator response state is determined to be insufficient recovery. When the overall response coefficient of the evaporator is between the normal response threshold and the insufficient recovery threshold, the evaporator response state is determined to be slow response.

[0010] Further, the step of synchronously generating the target opening degree of the electronic expansion valve and the target frequency of the compressor based on the evaporator response state includes: Determine the state correction coefficient based on the evaporator response state; The valve-machine coordinated adjustment coefficient is calculated based on the state correction coefficient, evaporator comprehensive response coefficient, system pressure ratio, and exhaust temperature. The opening increment of the electronic expansion valve and the frequency increment of the compressor are adjusted according to the valve-machine coordination adjustment coefficient.

[0011] Further, the step of adjusting the electronic expansion valve opening increment and the compressor frequency increment according to the valve-machine coordination adjustment coefficient includes: Obtain the basic control steps of the electronic expansion valve, and determine the electronic expansion valve opening increment by multiplying the basic control steps of the electronic expansion valve with the valve-mechanical coordination adjustment coefficient. Then, determine the target opening of the electronic expansion valve by summing the current opening of the electronic expansion valve with the electronic expansion valve opening increment. Obtain the compressor's base frequency increase, and determine the compressor frequency increment by multiplying the compressor's base frequency increase by the valve-machine coordinated adjustment coefficient. Then, determine the compressor's target frequency by summing the compressor's current frequency and the compressor frequency increment.

[0012] Furthermore, before generating the electronic expansion valve detection action, it also includes determining whether the detection execution conditions are met. The detection execution conditions include: the compressor frequency is stable, the electronic expansion valve is not in the limit position, the exhaust temperature is lower than the detection protection upper limit, the system pressure ratio is lower than the detection protection upper limit, and there is no defrosting command, no low pressure protection or high pressure protection alarm.

[0013] A second aspect of the invention provides a smart control system for heat pumps in cryogenic environments, the system comprising: The data acquisition module is used to acquire heat pump operating status data, which includes suction superheat, system pressure ratio, exhaust temperature, current opening degree of electronic expansion valve, and current compressor frequency. The detection execution module is used to generate an electronic expansion valve detection action based on the heat pump operating status data when the current frequency of the compressor is stable, and to record the heat pump operating status data before and after the detection to form valve detection response data; The status assessment module is used to calculate the comprehensive response coefficient of the evaporator based on the valve detection response data, and to classify the evaporator response status based on the comprehensive response coefficient of the evaporator. The collaborative control module is used to synchronously generate the target opening degree of the electronic expansion valve and the target frequency of the compressor based on the evaporator response state, and to control the electronic expansion valve and the compressor to perform.

[0014] The beneficial technical effects of the present invention are at least as follows: To address the aforementioned problems, this invention provides an intelligent control method and system for heat pumps in ultra-low temperature environments. By introducing controlled detection actions of an electronic expansion valve, it actively identifies the evaporator's true dynamic response capability at ultra-low temperatures, effectively solving the problems of control oscillation, excessively high exhaust temperature, and liquid slugging risk caused by system lag and strong coupling in existing technologies. This invention no longer relies solely on lagging suction superheat for feedback regulation; instead, it uses detection response data to calculate the evaporator's comprehensive response coefficient, classifying the evaporator state as normal response, slow response, or insufficient recovery. This allows the controller to distinguish between the actual liquid supply demand and the apparent high superheat caused by ultra-low temperature thermal inertia. Based on this state assessment, the target opening degree of the electronic expansion valve and the target frequency of the compressor are generated simultaneously, achieving valve-machine coordinated control. When the evaporator responds well, the system can actively increase heating output; when the response is slow or recovery is insufficient, the adjustment amplitude is automatically reduced, avoiding system instability caused by blindly increasing the frequency or opening the valve. This invention significantly improves the operational stability and heating efficiency of ultra-low temperature heat pumps under operating conditions of -25℃ to -40℃, reduces the risk of component damage, and exhibits superior dynamic adaptability, especially during defrosting recovery and sudden load changes. Attached Figure Description

[0015] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present invention. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort.

[0016] Figure 1 This is a flowchart of the intelligent control method for heat pumps in ultra-low temperature environments according to the present invention.

[0017] Figure 2 This is a framework diagram of the intelligent control system for heat pumps used in ultra-low temperature environments according to the present invention. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0019] In one or more embodiments, such as Figure 1 As shown, a smart control method for heat pumps in ultra-low temperature environments is disclosed, the method comprising the following: S1: Acquire heat pump operating status data, which includes suction superheat, system pressure ratio, exhaust temperature, current opening of electronic expansion valve, and current compressor frequency.

[0020] Specifically, the controller reads the intake temperature within a fixed control cycle. Evaporation pressure Condensing pressure Exhaust temperature Current opening degree of electronic expansion valve and the current frequency of the compressor And generate the operating status of the ultra-low temperature heat pump. . The temperature data is collected by a temperature sensor installed on the compressor suction line. The sensor is located between the evaporator outlet and the compressor suction port to reflect the actual temperature state of the refrigerant before it enters the compressor. The pressure is collected by an evaporator-side pressure sensor, with the pressure sampling port located on the evaporator outlet side. The pressure is collected by a condenser-side pressure sensor, with the pressure sampling port located between the compressor exhaust and the condenser inlet. Data is collected by an exhaust temperature sensor to reflect the compressor's exhaust heat load; Current step count feedback from the electronic expansion valve driver; The current operating frequency is fed back from the frequency converter. After the sensor data enters the controller, it undergoes timestamp consistency verification and valid range verification. If any data point for suction temperature, evaporation pressure, condensation pressure, or exhaust temperature is missing, exceeds the sensor's range, or the sampling time is asynchronous, or if the unit is in a defrosting, oil return, protection shutdown, or compressor start-up transition phase, the controller will not generate any data that can be used for detection. Only maintain the original protection control or conventional heating control. The controller obtains... Then, the evaporator-side saturation temperature is obtained based on the pressure-saturation temperature relationship of the refrigerant used in the unit. This correspondence originates from the thermodynamic properties of the refrigerant, and in engineering implementation, it can be obtained by querying and interpolating from the refrigerant property table preset within the controller; if If the reading is outside the range covered by the property table or below the lower reliability limit of the pressure sensor, no further detection will be performed in this cycle. Subsequently, the controller will determine the appropriate detection method based on the intake temperature. With saturation temperature Calculate the actual intake superheat : ; in, Indicates the actual intake superheat; This represents the value collected by the intake temperature sensor; Indicates evaporation pressure The corresponding saturation temperature; This represents the value collected by the evaporator-side pressure sensor. This formula originates from the definition of suction superheat in the refrigeration cycle, which is the degree of deviation of the actual suction temperature from the evaporator saturation temperature. Taking a unit using R410A refrigerant as an example, when the controller... Found -32, intake temperature When it is -24 hours, The calculation result is 8, indicating that the refrigerant is in a superheated state before entering the compressor. The variable is subsequently used in steps two (detection action judgment), three (evaporator response calculation), and four (target opening degree calculation of electronic expansion valve), thus it has a continuous application.

[0021] The controller obtains Then, continue according to the condensation pressure. With evaporation pressure Calculate the system pressure ratio : ; in, Indicates the system pressure ratio; This indicates the value collected by the condenser-side pressure sensor; This represents the value collected by the evaporator-side pressure sensor. This formula originates from the definition of the compression ratio during the compressor's compression process and is used to characterize the current compression load on the compressor. If the current... It is 3.2. If it is 0.4, then A value of 8 indicates that the compressor is operating at a higher pressure ratio. If... If the value is zero, negative, or lower than the minimum effective evaporation pressure set by the controller, the controller will not perform pressure ratio calculation and will directly enter low-pressure protection or disable the detection branch to avoid pressure ratio anomalies caused by invalid denominators. , , , and Combining to form the operating state of ultra-low temperature heat pump ,in Characterizes the refrigerant state on the suction side. and Characterizes the compressor's operating load and exhaust thermal state. Characterizes the current opening position of the electronic expansion valve. It represents the current operating frequency of the compressor. It also stores refrigerant type, control cycle number, sensor validity mark, whether it is in defrost or protection state, compressor frequency stability mark, and electronic expansion valve operability mark. The above data together form the basis for subsequent small-scale electronic expansion valve detection.

[0022] In ultra-low temperature heating processes, an excessively high intake superheat may correspond to different operating conditions. For example, High and At lower or medium levels, the evaporator may still have the capacity to accept more liquid; while when High and accompanied by higher During the rise, the evaporator's heat exchange recovery capacity may already be limited, and the compressor is also operating close to a heavy load. For example, if... It is already close to the maximum opening of the electronic expansion valve, even If the temperature is too high, the effective change that the valve can produce by continuing to operate will be relatively small; if During the frequency ramp-up phase, changes in suction superheat and evaporation pressure are simultaneously affected by changes in compressor flow rate. The controller... These states are recorded uniformly, allowing step two to determine whether to perform a small-scale electronic expansion valve probe based on the same operating state. In a typical operation, the controller reads... -24, according to Found The value is -32, and the calculation yields... The value is 8; read simultaneously 3.2 The value is 0.4, and the calculation yields... It is 8; if at this time Within the permissible range, Located within the operable range, If it remains stable, then it will form This information can serve as the basis for the small-scale electronic expansion valve detection performed in step two. Finally, this step outputs the operating status of the cryogenic heat pump. For use in step two; if If a valve is marked as undetectable, then step two will not generate valve detection response data.

[0023] S2: When the current frequency of the compressor is stable, generate an electronic expansion valve detection action based on the heat pump operating status data, and record the heat pump operating status data before and after the detection to form valve detection response data.

[0024] Specifically, this step follows the output of the ultra-low temperature heat pump operating status from step one. The controller from Read the actual intake superheat System pressure ratio Exhaust temperature Current opening degree of electronic expansion valve and the current frequency of the compressor Based on this, valve detection response data is generated. .in, Used to reflect the refrigerant state on the suction side. and Used to reflect the current operating load of the compressor and the thermal state of the exhaust gas. Used to indicate the current position of the electronic expansion valve. Used to determine the operating frequency maintained by the compressor during the detection period. In this step, the controller first... The permissible intensity of the electronic expansion valve's detection action is calculated, and the change in detection opening is determined based on the actual suction superheat. Finally, a detection process of "opening change - holding sampling - restoring opening" is executed once, converting the small movements of the electronic expansion valve into evaporator response data usable in step three. The detection action is only performed when the compressor frequency is stable, the electronic expansion valve is not at its limit, the exhaust temperature is below the detection protection upper limit, the system pressure ratio is below the detection protection upper limit, there is no defrost command, and there are no low-pressure or high-pressure protection alarms. If any of these conditions are not met, the controller will not issue a detection opening change amount and will record the reason for prohibiting detection in the current cycle.

[0025] The controller first calculates the detection intensity coefficient. This coefficient originates from the limiting concept and normalized margin evaluation method in engineering control. Pressure ratio margin, exhaust temperature margin, compressor frequency margin, and electronic expansion valve position margin are originally different physical quantities. The controller first converts each margin into a dimensionless proportion, then takes the minimum value as the common constraint for this detection action, ensuring that the detection intensity is determined by the factor closest to the operating boundary. The specific calculation is as follows: ; in, This indicates the intensity coefficient of the electronic expansion valve's detection action. This indicates the pressure ratio margin, determined by the controller based on... The relative position within the allowable probe pressure ratio range is calculated; This indicates the exhaust temperature margin ratio, determined by the controller based on... Calculated based on the relative position within the permissible range of exhaust temperature detection; This indicates the compressor frequency margin ratio, determined by the controller based on... The relative position within the permissible detection frequency range is calculated. This indicates the position margin ratio of the electronic expansion valve, determined by the controller based on... The relative distance to the opening boundary of the electronic expansion valve is calculated. The four margin ratios mentioned above are all calculated from the preset upper and lower limit parameters within the controller parameter area, with the conversion results limited to the range of 0 to 1. All terms on the right-hand side of the equation are proportional values. It is also a proportional value. Taking a single ultra-low temperature heating operation as an example, if the controller... get , , , ,but This indicates that the current detection action is mainly limited by the current position margin of the electronic expansion valve; if ,but This indicates that the pressure ratio has become the dominant factor limiting the detection action. If any margin ratio is zero, it means that the current operating boundary does not allow detection, and the controller directly prohibits this detection action.

[0026] In obtaining Then, the controller according to Calculate the change in the opening of the electronic expansion valve. This calculation stems from proportional control and actuator stepping limit control: the base probe steps provide identifiable small disturbances. Based on scaling this disturbance according to the current cryogenic operating boundary, the enhanced superheat term of the intake gas will cause the detection action to... A significantly higher level indicates better identification ability. The specific calculation is as follows: ; in, This indicates the change in the opening detected by the electronic expansion valve, which is calculated by the controller and then sent to the electronic expansion valve driver. This indicates that the calculation result will be taken as the integer number of steps that the electronic expansion valve driver can execute; This indicates the basic detection step count, which is determined by the minimum effective action step count of the electronic expansion valve and the unit commissioning results. It is only used for the valve detection action in step two. This represents the aforementioned detection intensity coefficient; This represents the superheat enhancement coefficient and is stored in the controller parameter area. This indicates the proportion of overheating, determined by the controller. The value is calculated relative to the initial and upper limits of the detection enhancement, and is limited to a range of 0 to 1. In this formula... and All correspond to the number of steps of the electronic expansion valve. , and All values ​​are proportional or coefficients, and the calculation result still corresponds to the number of steps in the electronic expansion valve. The controller makes its judgment after rounding. Whether the minimum effective number of steps of the electronic expansion valve has been reached, and simultaneously verify. The maximum permissible opening of the electronic expansion valve has not been exceeded; when When the minimum number of effective action steps is reached and the target detection opening is within the operable range, this small valve opening detection is executed; when When the number of effective action steps is lower than the minimum or the target detection opening exceeds the limit, the controller maintains the current opening of the electronic expansion valve. And in the next control cycle, based on Determine the detection conditions. , , , For example, the controller calculates... The electronic expansion valve performs approximately 5 small-amplitude valve opening detection steps; if the same... It occurs under operating conditions with even lower pressure ratio margin. If it drops to 0.30, then The detection action automatically decreases as the current operating boundary decreases.

[0027] Controller determination Then, first record the superheat of the inhalation air before detection. , Evaporation pressure before detection and the pressure ratio of the system before detection . The intake superheat was calculated using the same method as in step one. The data is collected by the evaporator-side pressure sensor before the detection action. The calculations are based on the condensing and evaporating pressures prior to the detection action. Subsequently, the controller maintains the compressor frequency at... The corresponding operating status is then sent to the electronic expansion valve actuator. The corresponding opening command causes the electronic expansion valve to move from its current opening position. The detection proceeds to the probe opening position. During the probe, the controller is prohibited from simultaneously issuing compressor frequency increase commands and conventional electronic expansion valve adjustment commands to prevent interference with the probe response from other actuator actions. If the exhaust temperature, pressure ratio, low-pressure protection, defrost request, or intake superheat rapidly decreases, triggering protection conditions, the controller immediately stops the probe and restores the electronic expansion valve to its original position. Nearby. After the electronic expansion valve reaches the detection opening, it maintains a position for several control cycles. During this holding period, the controller continuously reads the suction temperature, evaporation pressure, and condensation pressure, and calculates the suction superheat after detection according to the relationship in step one. , evaporation pressure after detection and the system pressure ratio after detection After sampling is complete, the controller will restore the electronic expansion valve to its original position. Nearby, a complete detection operation was completed.

[0028] In ultra-low temperature heating operation This reflects the dynamic response of the evaporator caused by a small change in the opening of the electronic expansion valve. If during a single operation... show High and Still within the permissible detection range Located near the middle opening of the electronic expansion valve and Stability will result in a relatively complete controller. And record the time before and after the detection. , , , , and If the valve is opened slightly... Compared decline, Compared Rebound, and Compared If the change is stable, then It includes the characteristic that the evaporator responds effectively to an increase in liquid supply; if the valve is opened slightly... The change is slow. The recovery is limited, and If an upward trend appears, then This includes the characteristic of slow response or insufficient recovery capability of the evaporator at ultra-low temperatures. This response characteristic is further processed in step three and transformed into the evaporator response state. If the detection is interrupted or the sampling data is incomplete, the controller will... If the detection response data is marked as invalid, step three will not update the evaporator response status based on this data.

[0029] This step outputs valve detection response data. . Including the change in aperture during this detection Pre-detection intake superheat , Evaporation pressure before detection , System pressure ratio before detection Detection of superheated intake air , evaporation pressure after detection System pressure ratio after detection and the compressor's current frequency maintained during the detection period. .in, According to the controller Calculated; and It is calculated from the saturation temperature corresponding to the intake temperature and evaporation pressure; and The data was collected by the evaporator-side pressure sensor. and Calculated from condensation pressure and evaporation pressure; Use the compressor's current frequency output from step one. It also saves the detection start time, detection duration, whether the detection was stopped, protection trigger reason, and data validity mark, which serve as the basis for step three to determine whether the evaporator comprehensive response coefficient can be calculated. As input to step three, it is used to generate the evaporator response state.

[0030] S3: Calculate the comprehensive response coefficient of the evaporator based on the valve detection response data, and classify the evaporator response state based on the comprehensive response coefficient of the evaporator.

[0031] Specifically, this step follows the valve detection response data output from step two. The controller from The change in aperture size during this detection was read from the data. Pre-detection intake superheat Detection of superheated intake air , Evaporation pressure before detection , evaporation pressure after detection , System pressure ratio before detection System pressure ratio after detection and the compressor's current frequency maintained during the detection period. And generate evaporator response status. Step two has completed a small-scale opening of the controlled electronic expansion valve and recorded the system response before and after the action. This step further organizes this response into a judgment result of the evaporator's recoverability. The basic logic is: the electronic expansion valve's detection action is equivalent to a small liquid supply disturbance. If the suction superheat decreases, the evaporation pressure rises, and the pressure ratio changes steadily after the disturbance, it indicates that the evaporator can absorb the increased refrigerant flow. If the decrease in suction superheat is limited, the rise in evaporation pressure is not significant, and the pressure ratio increases after the disturbance, it indicates that the evaporator's heat exchange recovery capability under the current ultra-low temperature conditions is insufficient, and the subsequent actions of the electronic expansion valve and compressor need to be limited. If a field is marked as invalid, probe aborted, or a critical field is missing, the controller will not calculate new data. It will continue to use the previous effective evaporator response state or enter a conservative control state to avoid invalid detection data affecting valve control.

[0032] The controller first calculates the overall response coefficient of the evaporator. This coefficient originates from the concept of unit input response gain in engineering control, which uses the output change caused by the controlled input to evaluate the response capability of the controlled object. This application applies this concept to the detection scenario of an ultra-low temperature heat pump electronic expansion valve, using the decrease in suction superheat and the proportion of evaporation pressure recovery as effective recovery terms. Simultaneously, it introduces a pressure ratio increase suppression term and a compressor frequency load term, so that the evaluation result simultaneously reflects the evaporator recovery effect and the compressor load status. The specific calculation is as follows: ; in, This represents the overall response coefficient of the evaporator, determined by the controller based on... Calculated; Indicates the pre-detection intake superheat. This indicates the intake superheat after detection; both are derived from the intake superheat calculated in step two in the same way as in step one. This represents the preset superheat normalized reference value in the controller parameter area, used to convert superheat changes into a proportional quantity; This represents the weighting of the evaporation pressure response, which is determined during unit commissioning based on the impact of evaporation pressure recovery on heating stability. Indicates the evaporation pressure before detection. The readings indicate the evaporation pressure after detection; both are acquired by the evaporation-side pressure sensor. This indicates the change in the opening degree of the electronic expansion valve detected during step two. This indicates the basic number of detection steps used in step two, which is stored in the controller parameter area and used to convert the current detection action into relative action intensity; This represents the pressure ratio increase suppression coefficient, which is set in the controller parameter area. Indicates the system pressure ratio before detection. This indicates the system pressure ratio after detection; both are calculated from the condensing pressure and the evaporating pressure. This represents the frequency load correction factor, which is determined by the compressor's operating and commissioning parameters. This indicates the current compressor frequency maintained during the detection period; This indicates the upper limit of the allowable detection frequency preset in the controller parameter area. In this formula, both terms in the numerator are proportional quantities, representing the effective recovery of the evaporator after the detection action; the denominator contains... This indicates the intensity of the current detection action relative to the baseline detection action. The pressure ratio increase suppression term represents the additional impact of the compression load after detection, and the frequency load term represents the impact of the current cycle quantity level on the response evaluation. If... , , or If the value is zero or lower than the controller's effective lower limit, the controller will not execute the formula calculation; if the calculated effective recovery term is negative, it indicates that the direction of change in the intake superheat or evaporation pressure after detection is unfavorable, and the controller will treat this response as a low response and record the cause of the abnormal response.

[0033] During an ultra-low temperature heating operation, step two output... In the controller parameter area Pre-detection intake superheat After detection, the superheat of the intake air Normalized reference value for superheat evaporation pressure before detection Detection of evaporation pressure System pressure ratio before detection After detection, the system pressure ratio The compressor's current frequency during the detection period Allowed detection frequency limit and take , , The controller calculates the intake superheat recovery ratio as follows: The relative recovery rate of evaporation pressure is After pressure response weighting correction, it becomes The total number of effective recovery items is The detection action intensity item is The pressure ratio increase inhibition term is The frequency load item is ,therefore The results indicate that the evaporator recovered somewhat after the electronic expansion valve opened slightly, but this recovery was corrected by both the increased pressure ratio and the higher compressor frequency.

[0034] The controller gets Then, based on the preset normal response threshold in the controller parameter area... and insufficient recovery threshold Generate evaporator response status . The determination is made under the ultra-low temperature commissioning conditions where the evaporator can stably accept increased liquid supply, the suction superheat decreases significantly, and the evaporation pressure recovers to a stable level. The determination was made under ultra-low temperature commissioning conditions where the evaporator recovery was slow, the pressure ratio changed unfavorably, or the heating performance fluctuated significantly. Higher than The state generation rules are as follows: ; in, This indicates the evaporator response status, which is output by the controller to step four. This represents the overall response coefficient of the aforementioned evaporator; Indicates the normal response threshold; This indicates insufficient recovery threshold. If the debugging parameters include... , The above calculation yields This will cause the controller to The response is deemed normal; if calculated under another operating condition... ,but The response is deemed slow; if calculated... ,but The recovery is deemed insufficient. Based on this segmentation rule, the valve detection response data obtained in step two... It is converted to a control state that can be directly used in step four. If Not higher than If the threshold is not calibrated, the controller will not use the segmented rule to update the state, but will instead enter a conservative control state and indicate that the parameter calibration is abnormal.

[0035] In actual control process, and The corresponding relationship is clearly reflected in three types of operating conditions. In the first type of operating condition, the electronic expansion valve executes... back, Compared A significant decrease Compared A steady recovery, and Compared With minimal changes, the controller calculates a higher value. The evaporator response status is normal. In the second type of operating condition, There has been some decline, but the magnitude is limited. The recovery was slow, and at the same time There was a certain increase, and the controller calculated a moderate level. The evaporator response is sluggish. In the third operating condition, The changes are very small. The recovery is not significant, and Significantly higher The controller calculates a lower The evaporator response status is insufficient recovery. All three states mentioned above originate from the response results of the same electronic expansion valve detection action, reflecting the evaporator's true tolerance to changes in liquid supply at ultra-low temperatures. If insufficient recovery is detected for multiple consecutive valid detection cycles, the controller can increase the defrost judgment priority or limit subsequent frequency increase requests, but this processing is still bounded by the unit's existing defrost and protection logic.

[0036] This step outputs the evaporator response status. And retain the corresponding evaporator overall response coefficient. .in, Depend on In , , , , , , and Calculated together; Depend on and , The comparison yields the results. Step four will use... and As input, the controller generates and executes the target opening degree of the electronic expansion valve and the target frequency of the compressor. , The valid markers and threshold versions are detected and written into the running log for subsequent parameter verification and fault diagnosis.

[0037] S4: Based on the evaporator response status, synchronously generate the target opening degree of the electronic expansion valve and the target frequency of the compressor, and control the electronic expansion valve and the compressor to execute.

[0038] Specifically, this step follows the evaporator response status output in step three. Combined response coefficient of evaporator The controller generates and executes the target opening degree of the electronic expansion valve based on the evaporator's actual response capability to the electronic expansion valve's detection action under the current ultra-low temperature conditions. and compressor target frequency Step three has already utilized valve detection response data. The overall response coefficient of the evaporator was calculated. and according to The relationship between the evaporator response state and a preset threshold is used to generate the evaporator response state. This step further integrates the evaporator's recovery capability directly into the joint control process of the electronic expansion valve and compressor, ensuring that the valve's liquid supply capacity and compressor circulation changes are based on the evaporator's actual handling capacity. Under ultra-low temperature heating conditions, the evaporator's thermal inertia and heat exchange recovery rate are significantly lower than under normal temperature conditions. When the evaporator's recovery capability is insufficient, if the electronic expansion valve continues to open rapidly and the compressor frequency is increased simultaneously, the system is prone to rapid increases in pressure ratio, increased exhaust temperature, and accumulation of liquid refrigerant. Therefore, this step uses the same set of evaporator response data to simultaneously constrain the actions of the electronic expansion valve and compressor, ensuring that their trends remain consistent during ultra-low temperature operation. If step three does not output a valid response... If the unit has entered defrosting, protection shutdown, exhaust temperature over-limit, low pressure protection, or compressor frequency limiting state, the controller will not perform frequency increase and valve opening coordinated action, but will maintain or switch to the unit's existing protection control.

[0039] The controller first reads the actual intake superheat from steps one and three, respectively. System pressure ratio Exhaust temperature Current opening degree of electronic expansion valve Compressor current frequency Evaporator response status Combined response coefficient of evaporator .in, It originates from the actual intake superheat calculated in step one based on the saturation temperature corresponding to the intake temperature and evaporation pressure. It originates from the system pressure ratio calculated in step one based on the condensation pressure and the evaporation pressure; Sourced from the exhaust temperature sensor; The current opening degree is derived from feedback from the electronic expansion valve actuator; The compressor operating frequency is derived from the feedback from the frequency converter or the current output from the controller; and This data originates from step three, based on the valve detection response data. The calculated evaporator response results. The controller, based on... Generate state correction coefficients , among which, when In response to normal conditions, Take the first correction value; when In case of slow response, Take the second correction value; when To recover from insufficient, The third correction value is taken, where the first correction value is greater than the second correction value, and the second correction value is greater than the third correction value. These three correction values ​​are stored in the controller parameter area and are calibrated during the unit's cryogenic heating commissioning process. Subsequently, the controller calculates the valve-machine coordinated adjustment coefficient. This coefficient originates from the concept of joint gain adjustment in engineering control, which uses the state of the same controlled object to simultaneously correct the amplitude of the actions of multiple actuators. This application introduces... The corresponding state correction coefficient is added, along with a joint suppression term for pressure ratio and exhaust temperature, so that the evaporator response state, evaporator comprehensive response coefficient, pressure ratio, and exhaust temperature jointly determine the action range of the electronic expansion valve and compressor. The specific calculation is as follows: ; in, This represents the valve-mechanism coordinated adjustment coefficient, which is calculated by the controller based on the current operating status. Indicates the evaporator response status Determined state correction coefficients; This represents the overall response coefficient of the evaporator obtained in step three; This represents the pressure ratio suppression coefficient, which is determined by the unit's commissioning parameters; This indicates the system pressure ratio in step one; This indicates that the preset pressure ratio reference value in the controller parameter area is obtained by calibration of the unit under stable heating conditions; This represents the exhaust temperature suppression coefficient, which is determined by the compressor's thermal load adjustment parameters. This indicates the exhaust temperature in step one; This indicates the preset exhaust temperature reference value in the controller parameter area; and This is used to introduce a suppressive effect only when the pressure ratio and exhaust temperature are higher than reference values. In this formula, , Both the pressure ratio suppression term and the exhaust temperature suppression term are proportional or coefficients, therefore It remains a dimensionless coefficient. The physical meaning of this formula is: the better the evaporator's response state, the higher the overall response coefficient. The larger the pressure ratio, the higher the exhaust temperature. The smaller the value, the more limited the synchronization of the subsequent electronic expansion valve and compressor operation. If... If the value is invalid or less than zero, the controller will... Treat it as zero or a conservative lower limit, and do not increase the valve opening and compressor frequency accordingly.

[0040] For example, in an ultra-low temperature heating operation, step three outputs For slow response, the controller according to Pick Meanwhile, step three outputs In step one , In the controller parameter area , , , The controller first calculates the pressure ratio additional term as follows: The exhaust temperature additional item is The final result is: ; The results indicate that under the current ultra-low temperature conditions, the evaporator possesses a certain recovery capability, but its response state, pressure ratio, and exhaust temperature collectively limit the valve mechanism's action range. Therefore, the subsequent electronic expansion valve and compressor both employ relatively gradual changes. In another operating condition... For a normal response, and and If they are all close to the reference value, then The pressure ratio and exhaust temperature components are relatively high, with the latter two being close to 1. The increase will be significant, indicating that the evaporator's recovery capacity can be more fully utilized to increase the circulation rate. Subsequent simultaneous participation and The calculations are used to ensure that valve actions and compressor actions use the same evaporator response constraints.

[0041] The controller gets Then, the target opening degree of the electronic expansion valve is generated based on the same valve mechanism coordination adjustment coefficient. and compressor target frequency The controller parameter area presets the basic control steps for the electronic expansion valve. and compressor base frequency increase . This indicates the basic control step number of the electronic expansion valve used for actual control in step four, and its function differs from the basic detection step number in step two. ; This represents the preset compressor base frequency increase value in the controller parameter area. The specific calculation is as follows: ; in, The target opening degree of the electronic expansion valve is indicated and sent from the controller to the electronic expansion valve driver. This indicates the current opening degree of the electronic expansion valve in step one; This indicates that the calculation result is converted into an integer change that the executor can execute; Indicates the basic control steps of the electronic expansion valve; This represents the aforementioned valve-mechanism coordinated adjustment coefficient; This represents the intake superheat enhancement coefficient, which is determined by the unit commissioning parameters. This indicates the actual intake superheat in step one; This represents the normalized reference value for superheat in step three; This indicates the target frequency of the compressor, which is sent from the controller to the frequency converter. This indicates the current frequency of the compressor in step one; This represents the compressor's base frequency increase. This formula originates from the concept of combined gain correction between proportional control and actuators. The base control steps of the electronic expansion valve provide the base liquid supply change, and the compressor's base frequency increase provides the base circulation change. Simultaneously, the amplitude of both actions is adjusted so that changes in liquid supply and circulation volume are based on the same evaporator response state. The controller, upon receiving... and Subsequently, the control is limited based on the minimum and maximum opening of the electronic expansion valve, the lowest and highest frequency of the compressor, the frequency change slope, the exhaust temperature protection, and the pressure ratio protection. If the target value after limiting is not significantly different from the current value, only the control result for this cycle is recorded and no action is issued.

[0042] Taking a single operating condition as an example, if in step one... , , Step three In the controller parameter area , , The aforementioned calculations yielded Then the controller calculates the target opening increment of the electronic expansion valve as follows: After rounding, we get approximately two steps; the target frequency increment of the compressor is... Rounded down, we get approximately 2. Therefore, the target opening of the electronic expansion valve is... Approximately 222, compressor target frequency Approximately 72. If in another operating condition... In response to normal, higher and If they are all close to the reference value, then Increase and Increase accordingly; if To recover from the deficiency, reduce, Consequently, the change in the electronic expansion valve opening and the compressor frequency decrease synchronously. If detected after execution... Quickly reduce to the liquid shock risk range rapid rise or If the exhaust temperature exceeds the protection value, the controller cancels the frequency increase request for this cycle and enters protection correction or recovery control.

[0043] This step ultimately outputs the target opening degree of the electronic expansion valve. and compressor target frequency .in, From step one This is determined together with the electronic expansion valve opening increment calculated in this step; From step one This is determined together with the compressor frequency increase calculated in this step. The controller will... Send to the electronic expansion valve driver, The data is sent to the compressor inverter to complete valve-machine coordinated control based on the evaporator response status. The controller also reads new data after the action is executed. , , and Record the target opening degree, target frequency, actual execution feedback, and protection trigger status as data for the next control cycle. This forms the basis for subsequent parameter verification, thus creating a closed loop of "operational status - valve detection - response status - valve control - execution feedback".

[0044] In one or more embodiments, such as Figure 2 As shown, a smart control system for heat pumps used in ultra-low temperature environments is disclosed, the system comprising: The data acquisition module is used to acquire heat pump operating status data, which includes suction superheat, system pressure ratio, exhaust temperature, current opening degree of electronic expansion valve, and current compressor frequency. The detection execution module is used to generate an electronic expansion valve detection action based on the heat pump operating status data when the current frequency of the compressor is stable, and to record the heat pump operating status data before and after the detection to form valve detection response data; The status assessment module is used to calculate the comprehensive response coefficient of the evaporator based on the valve detection response data, and to classify the evaporator response status based on the comprehensive response coefficient of the evaporator. The collaborative control module is used to synchronously generate the target opening degree of the electronic expansion valve and the target frequency of the compressor based on the evaporator response state, and to control the electronic expansion valve and the compressor to perform.

[0045] It is worth noting that the specific workflow of the intelligent control system for heat pumps in ultra-low temperature environments provided in this embodiment of the invention is the same as that of the intelligent control method for heat pumps in ultra-low temperature environments described in the above embodiments, and will not be repeated here.

[0046] This invention also provides a heat pump intelligent control device for cryogenic environments, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the steps described in the above embodiments of the heat pump intelligent control method for cryogenic environments, for example... Figure 1 The steps S1 to S4 described above; or, when the processor executes the computer program, it implements the functions of each module in the above system embodiments.

[0047] For example, the computer program may be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules may be a series of computer program instruction segments capable of performing specific functions, which describe the execution process of the computer program in the intelligent control device for heat pumps used in cryogenic environments.

[0048] The intelligent control device for heat pumps used in ultra-low temperature environments can be a computing device such as a desktop computer, laptop, handheld computer, or cloud server. This intelligent control device may include, but is not limited to, a processor and memory. Those skilled in the art will understand that the intelligent control device may also include input / output devices, network access devices, buses, etc.

[0049] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the intelligent heat pump control device for cryogenic environments, connecting all parts of the device via various interfaces and lines.

[0050] The memory can be used to store the computer program and / or modules. The processor implements various functions of the intelligent control device for heat pumps in ultra-low temperature environments by running or executing the computer program and / or modules stored in the memory, and by calling data stored in the memory. The memory may mainly include a program storage area and a data storage area. The program storage area may store the operating system, at least one application program required for a function, etc.; the data storage area may store data created according to the operation of the controller, etc. In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, memory, plug-in hard disk, smart media card (SMC), secure digital card (SD card), flash card, at least one disk storage device, flash memory device, or other volatile solid-state storage devices.

[0051] The integrated module of the heat pump intelligent control device for ultra-low temperature environments, if implemented as a software functional unit and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0052] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0053] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A smart control method for heat pumps used in ultra-low temperature environments, characterized in that, The method includes: Acquire heat pump operating status data, which includes suction superheat, system pressure ratio, exhaust temperature, current opening of electronic expansion valve, and current compressor frequency; When the compressor's current frequency is stable, an electronic expansion valve detection action is generated based on the heat pump's operating status data, and the heat pump's operating status data before and after the detection is recorded to form valve detection response data; The comprehensive response coefficient of the evaporator is calculated based on the valve detection response data, and the evaporator response state is classified based on the comprehensive response coefficient of the evaporator. Based on the evaporator response status, the target opening degree of the electronic expansion valve and the target frequency of the compressor are generated synchronously, and the electronic expansion valve and the compressor are controlled to operate.

2. The intelligent control method for heat pumps in ultra-low temperature environments according to claim 1, characterized in that, The acquisition of heat pump operating status data includes: Read the intake temperature, evaporation pressure, condensation pressure, and exhaust temperature within a fixed control cycle; The intake superheat is calculated based on the saturation temperature corresponding to the intake temperature and the evaporation pressure. The system pressure ratio is calculated based on the ratio of the condensation pressure to the evaporation pressure.

3. The intelligent control method for heat pumps in ultra-low temperature environments according to claim 1, characterized in that, When the compressor's current frequency is stable, generating an electronic expansion valve detection action based on the heat pump's operating status data includes: The detection intensity coefficient is calculated based on the intake superheat, system pressure ratio, exhaust temperature, and current opening of the electronic expansion valve. The change in the electronic expansion valve's detection opening is determined based on the detection intensity coefficient and the intake superheat. While keeping the compressor's current frequency constant, the electronic expansion valve is controlled to perform the action of detecting changes in its opening degree.

4. The intelligent control method for heat pumps in ultra-low temperature environments according to claim 3, characterized in that, The recorded heat pump operating status data before and after the detection includes: Before the electronic expansion valve performs the detection action, record the intake superheat, evaporation pressure, and system pressure ratio before detection. After the electronic expansion valve performs the detection action and maintains it for a preset time, record the intake superheat, evaporation pressure, and system pressure ratio after detection.

5. The intelligent control method for heat pumps in ultra-low temperature environments according to claim 1, characterized in that, The calculation of the evaporator comprehensive response coefficient based on the valve detection response data includes: The effective recovery term is calculated based on the difference between the inhalation superheat before and after detection, and the ratio of the change in evaporation pressure before and after detection. The suppression term is calculated based on the change in system pressure ratio after detection compared to before detection, and the current frequency of the compressor. The overall response coefficient of the evaporator is determined based on the ratio of the effective recovery term to the suppression term.

6. The intelligent control method for heat pumps in ultra-low temperature environments according to claim 5, characterized in that, The process of classifying the evaporator response state based on the comprehensive evaporator response coefficient includes: The overall response coefficient of the evaporator is compared with the preset normal response threshold and insufficient recovery threshold; When the overall response coefficient of the evaporator is greater than the normal response threshold, the evaporator response status is determined to be normal. When the overall response coefficient of the evaporator is less than the insufficient recovery threshold, the evaporator response state is determined to be insufficient recovery. When the overall response coefficient of the evaporator is between the normal response threshold and the insufficient recovery threshold, the evaporator response state is determined to be slow response.

7. The intelligent control method for heat pumps in ultra-low temperature environments according to claim 1, characterized in that, The step of synchronously generating the target opening degree of the electronic expansion valve and the target frequency of the compressor based on the evaporator response state includes: Determine the state correction coefficient based on the evaporator response state; The valve-machine coordinated adjustment coefficient is calculated based on the state correction coefficient, evaporator comprehensive response coefficient, system pressure ratio, and exhaust temperature. The opening increment of the electronic expansion valve and the frequency increment of the compressor are adjusted according to the valve-machine coordination adjustment coefficient.

8. The intelligent control method for heat pumps in ultra-low temperature environments according to claim 7, characterized in that, The step of adjusting the electronic expansion valve opening increment and the compressor frequency increment according to the valve-machine coordination adjustment coefficient includes: Obtain the basic control steps of the electronic expansion valve, and determine the electronic expansion valve opening increment by multiplying the basic control steps of the electronic expansion valve with the valve-mechanical coordination adjustment coefficient. Then, determine the target opening of the electronic expansion valve by summing the current opening of the electronic expansion valve with the electronic expansion valve opening increment. Obtain the compressor's base frequency increase, and determine the compressor frequency increment by multiplying the compressor's base frequency increase by the valve-machine coordinated adjustment coefficient. Then, determine the compressor's target frequency by summing the compressor's current frequency and the compressor frequency increment.

9. The intelligent control method for heat pumps in ultra-low temperature environments according to claim 1, characterized in that, Before generating the electronic expansion valve detection action, it is also necessary to determine whether the detection execution conditions are met. The detection execution conditions include: the compressor frequency is stable, the electronic expansion valve is not in the limit position, the exhaust temperature is lower than the detection protection upper limit, the system pressure ratio is lower than the detection protection upper limit, and there is no defrosting command, no low pressure protection or high pressure protection alarm.

10. A heat pump intelligent control system for ultra-low temperature environments, characterized in that, The system includes: The data acquisition module is used to acquire heat pump operating status data, which includes suction superheat, system pressure ratio, exhaust temperature, current opening degree of electronic expansion valve, and current compressor frequency. The detection execution module is used to generate an electronic expansion valve detection action based on the heat pump operating status data when the current frequency of the compressor is stable, and to record the heat pump operating status data before and after the detection to form valve detection response data; The status assessment module is used to calculate the comprehensive response coefficient of the evaporator based on the valve detection response data, and to classify the evaporator response status based on the comprehensive response coefficient of the evaporator. The collaborative control module is used to synchronously generate the target opening degree of the electronic expansion valve and the target frequency of the compressor based on the evaporator response state, and to control the electronic expansion valve and the compressor to execute.

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