A refrigerating unit driving board anti-condensation icing method and system and a refrigerating unit

Abstract

A refrigeration unit driving board anti-condensation icing method and system and a refrigeration unit, comprising: taking into account the hysteresis effect of air humidity change, correcting the air instantaneous dew point temperature based on the ambient temperature and the ambient humidity; calculating the refrigerant thermodynamic state factor based on the superheat; combining the corrected air instantaneous dew point temperature, the refrigerant thermodynamic state factor and the suction pressure to calculate the dynamic safety boundary temperature of the driving board surface; determining whether there is a condensation risk, icing risk or liquid impact risk; if there is a condensation risk, entering a pre-warning intervention mode, if there is an icing risk or liquid impact risk, entering an emergency protection mode; if the driving board surface temperature exceeds the set recovery temperature for a second set time, the EEV opening, the compressor frequency and the PTC power are all restored to the corresponding values during normal operation. The present application accurately distinguishes and classifies different risks, effectively balancing the anti-condensation effect and system operation stability.

Description

Technical Field

[0001] This invention belongs to the field of anti-condensation and anti-icing technology for refrigeration units, and more specifically, relates to a method, system and refrigeration unit for preventing condensation and icing on the drive plate of a refrigeration unit. Background Technology

[0002] With the deepening development of the cold chain logistics industry, the requirements for energy efficiency and stability of refrigeration systems in low-temperature cold storage are becoming increasingly stringent. Currently, fixed-frequency refrigeration units based on hot-flecked defrosting technology have achieved a high level of engineering maturity, and the industry is accelerating its transition to variable-frequency technology. However, when coupling variable-frequency technology with hot-flecked defrosting processes for low-temperature environments, several key technical bottlenecks still exist: Risks of condensation and icing caused by refrigerant cooling: Under hot defrosting conditions, the system operates at high temperature and high pressure, while the ambient temperature of the cold storage remains low. At this time, after some of the liquid refrigerant is throttled and depressurized by the electronic expansion valve, its temperature drops sharply to below 0°C. If the drive board adopts a direct refrigerant contact cooling architecture, the low temperature refrigerant will cause severe condensation or even freezing on the substrate surface and internal components. Ice accumulation not only significantly deteriorates electrical insulation performance, inducing dielectric breakdown or short circuit faults, but may also cause mechanical breakage of components due to volume expansion, ultimately leading to thermal failure and burnout of the drive module. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method, system, and refrigeration unit for preventing condensation and icing on the drive plate of a refrigeration unit.

[0004] The present invention adopts the following technical solution.

[0005] The first aspect of this invention provides a method for preventing condensation and icing on the drive plate of a refrigeration unit, comprising: The system acquires the superheat and instantaneous air dew point temperature; takes into account the hysteresis effect of changes in air humidity, and corrects the instantaneous air dew point temperature based on ambient temperature and humidity; calculates the refrigerant thermodynamic state factor based on the superheat; calculates the dynamic safety boundary temperature of the drive plate surface by combining the corrected instantaneous air dew point temperature, refrigerant thermodynamic state factor, and suction pressure; and determines whether there is a risk of condensation, freezing, or liquid slugging by the relationship between the drive plate surface temperature, the dynamic safety boundary temperature, and the freezing point temperature, as well as the relationship between the superheat and the set liquid slugging risk threshold. If there is a risk of condensation, the opening change rate of the EEV is calculated based on the drive plate surface temperature and compressor operating conditions, and the EEV opening is reduced according to the opening change rate of the EEV; and the dynamic lower limit is calculated based on the refrigerant thermodynamic state factor, and the compressor frequency is increased to the dynamic lower limit; after reducing the EEV opening and increasing the compressor frequency to the dynamic lower limit, if the duration of the drive plate surface temperature being less than or equal to the dynamic safety boundary temperature exceeds the set first time, the PTC is activated; If there is a risk of icing or liquid slugging, the EEV target opening is calculated based on the set expected superheat, the compressor target frequency is calculated based on the exhaust temperature, and the PTC target power is calculated through thermal balance constraints. The EEV opening, compressor frequency and PTC power are then adjusted to the EEV target opening, compressor target frequency and PTC target power, respectively. If the surface temperature of the drive board exceeds the set recovery temperature for a set period of time, the EEV opening, compressor frequency, and PTC power will all be restored to their normal operating values.

[0006] Preferably, the hysteresis effect taking into account changes in air humidity is corrected for the instantaneous dew point temperature of the air based on ambient temperature and ambient humidity, specifically as follows: The corrected instantaneous dew point temperature is obtained by adding the product of the rate of change of ambient humidity and the set first ambient thermal inertia coefficient to the instantaneous air dew point temperature, and then adding the product of the square of the rate of change of ambient temperature and the set second ambient thermal inertia coefficient.

[0007] Preferably, the calculation of the refrigerant thermodynamic state factor based on the superheat specifically involves: The superheat is the intake temperature minus the saturation temperature, and the saturation temperature is obtained by looking up a table based on the current intake pressure. If the superheat is less than the liquid slugging risk threshold, the refrigerant thermodynamic state factor is 0; if the superheat is greater than or equal to the liquid slugging risk threshold but less than the rated superheat, the refrigerant thermodynamic state factor is equal to the difference between the superheat and the liquid slugging risk threshold divided by the difference between the rated superheat and the liquid slugging risk threshold; if the superheat is greater than or equal to the rated superheat, the refrigerant thermodynamic state factor is 1.

[0008] Preferably, the calculation of the dynamic safety boundary temperature of the drive plate surface by combining the corrected instantaneous dew point temperature of the air, the refrigerant thermodynamic state factor, and the suction pressure specifically includes: Subtract the refrigerant thermodynamic state factor from 1, and multiply the result by the set refrigerant low-quality penalty coefficient to obtain the refrigerant low-quality penalty item. The difference between the surface temperature of the drive board and the corrected instantaneous dew point temperature of the air is multiplied by the set speed coefficient, then multiplied by -1. The result of the multiplication is used as the exponent, and the natural base is used as the base. The result of the exponentiation is then multiplied by the set approach risk acceleration coefficient as the approach risk acceleration term. The pressure correction term is obtained by multiplying the normalized intake pressure by the set high-pressure condensation coefficient. The dynamic safety boundary temperature is obtained by superimposing the corrected instantaneous air dew point temperature, the refrigerant low quality penalty term, the approach risk acceleration term, and the pressure correction term.

[0009] Preferably, the determination of whether there is a risk of condensation, freezing, or liquid hammer specifically involves: If the superheat is less than the set liquid slugging risk threshold, it is judged as liquid slugging risk; If there is no risk of liquid slugging, determine whether the surface temperature of the drive board is less than or equal to the dynamic safety boundary temperature. If so, determine whether the surface temperature of the drive board is greater than the freezing point temperature. If so, determine the risk of condensation; otherwise, determine the risk of freezing.

[0010] Preferably, the calculation of the EEV opening change rate based on the drive board surface temperature and compressor operating conditions specifically involves: The difference between the dynamic safety boundary temperature and the drive board surface temperature is divided by the set reference temperature difference benchmark. The result of the division is used as the base, and the set second empirical gain coefficient is used as the exponent. The result of the exponent calculation is multiplied by the first empirical gain coefficient and then multiplied by -1 to obtain the EEV opening adjustment rate for temperature control. The compressor operating condition is the discharge pressure. If the discharge pressure is greater than the set maximum discharge pressure, the compressor operating condition coupling factor is the first coupling factor; if the discharge pressure is less than or equal to the set maximum discharge pressure and greater than the set minimum discharge pressure, the compressor operating condition coupling factor is the second coupling factor; if the discharge pressure is less than or equal to the set minimum discharge pressure, the compressor operating condition coupling factor is the third coupling factor. The first coupling factor is less than the second coupling factor, and the second coupling factor is less than the third coupling factor; The opening change rate of EEV is obtained by multiplying the temperature-controlled EEV opening adjustment rate by the compressor operating condition coupling factor.

[0011] Preferably, the calculation of the dynamic lower limit based on the refrigerant thermodynamic state factor specifically includes: Subtract the refrigerant thermodynamic state factor from 1, multiply the result by the set compensation coefficient, and add the result to the lower limit of the base compressor frequency to obtain the calculated dynamic lower limit.

[0012] Preferably, if the duration of the drive board surface temperature being less than or equal to the dynamic safety boundary temperature exceeds a set first time, then the PTC is activated, specifically: The power required to start the PTC is obtained by subtracting the surface temperature of the drive board at the moment of PTC startup from the dynamic safety boundary temperature, multiplying by the thermal efficiency coefficient of the PTC, and then multiplying by the set heating gain coefficient.

[0013] Preferably, the step of back-calculating the EEV target opening based on the set expected superheat and back-calculating the compressor target frequency based on the exhaust temperature specifically involves: By inputting the current condensing pressure, evaporating pressure, and set desired superheat into the compressor characteristic curve, the refrigerant mass flow rate is obtained by back-calculation. The EEV opening corresponding to the refrigerant mass flow rate is obtained by looking up the table as the EEV target opening. By obtaining the mapping function between exhaust temperature and compressor target frequency through simulation or historical data, the minimum frequency at which the exhaust temperature exceeds the set exhaust temperature threshold can be deduced as the compressor target frequency.

[0014] Preferably, the calculation of the PTC target power through thermal balance constraints specifically involves: The thermal balance constraint is that the heat absorbed by the drive plate is less than or equal to the heat released by the drive plate. Multiply the difference between the refrigerant temperature and the surface temperature of the drive plate by the refrigerant's convective heat transfer coefficient and then by the heat transfer area. Add the PTC power to the result of the multiplication to get the heat absorbed by the drive plate. Multiply the difference between the surface temperature of the drive plate and the ambient temperature by the air convection heat transfer coefficient and then by the heat transfer area. Add the result of the multiplication to the other heat losses of the drive plate to equal the heat released by the drive plate. If the minimum PTC power that satisfies the thermal balance constraint is less than 0, the PTC will not be activated; otherwise, the minimum PTC power that satisfies the thermal balance constraint will be used as the target PTC power.

[0015] A second aspect of the present invention provides a refrigeration unit drive board anti-condensation and icing system based on the method described in the first aspect of the present invention, comprising a risk assessment module, an early warning intervention module, an emergency protection module, and a recovery module, specifically as follows: Risk assessment module: used to acquire superheat and instantaneous air dew point temperature; taking into account the hysteresis effect of air humidity changes, correcting the instantaneous air dew point temperature based on ambient temperature and humidity; calculating the refrigerant thermodynamic state factor based on the superheat; calculating the dynamic safety boundary temperature of the drive plate surface by combining the corrected instantaneous air dew point temperature, refrigerant thermodynamic state factor and suction pressure; determining whether there is a risk of condensation, freezing or liquid slugging by the relationship between the drive plate surface temperature and the dynamic safety boundary temperature and freezing point temperature, and the relationship between superheat and the set liquid slugging risk threshold. Early warning and intervention module: If there is a risk of condensation, it calculates the opening change rate of EEV based on the drive plate surface temperature and compressor operating conditions, reduces the EEV opening according to the opening change rate of EEV; and calculates the dynamic lower limit based on the refrigerant thermodynamic state factor, and increases the compressor frequency to the dynamic lower limit; after reducing the EEV opening and increasing the compressor frequency to the dynamic lower limit, if the duration of the drive plate surface temperature being less than or equal to the dynamic safety boundary temperature exceeds the set first time, the PTC is activated. Emergency protection module: If there is a risk of icing or liquid slugging, it will back-calculate the EEV target opening based on the set expected superheat, back-calculate the compressor target frequency based on the exhaust temperature, and calculate the PTC target power through thermal balance constraints, and adjust the EEV opening, compressor frequency and PTC power to the EEV target opening, compressor target frequency and PTC target power respectively. Recovery module: If the surface temperature of the drive board exceeds the set recovery temperature for a set period of time, the EEV opening, compressor frequency and PTC power will be restored to the values ​​corresponding to normal operation.

[0016] A third aspect of the present invention provides a refrigeration unit that integrates the anti-condensation and anti-icing system for the refrigeration unit drive board described in the second aspect of the present invention.

[0017] The beneficial effects of this invention are compared with those of the prior art: 1. This invention achieves precise differentiation and graded control of condensation, icing, and liquid slugging risks by introducing air humidity hysteresis correction, refrigerant thermodynamic state factor, and dynamic safety boundary temperature. Based on the risk type, differentiated EEV opening, compressor frequency, and PTC power are coordinated and adjusted. This approach avoids excessive intervention in the early stages of condensation through fine-tuning, while providing strong protection during icing or liquid slugging. It effectively balances anti-condensation performance with system operational stability, improving the long-term reliability and safety of the refrigeration unit's drive board in harsh and humid environments.

[0018] 2. This invention corrects the dew point temperature by adjusting the rate of change of ambient temperature and humidity, which can effectively compensate for the deviation caused by sensor response lag and ambient thermal inertia.

[0019] 3. This invention maps superheat to a refrigerant thermodynamic state factor, which can smoothly reflect the degree of deterioration of the refrigerant as it approaches the liquid hammer boundary from its normal state.

[0020] 4. This invention constructs a dynamic safety boundary temperature by integrating three factors: refrigerant low-quality penalty, approach risk acceleration, and high-pressure condensation correction. It not only considers the deteriorating effect of refrigerant liquid on evaporation temperature, but also uses an exponential term to characterize the nonlinear characteristics of the risk amplification when the surface temperature approaches the dew point. At the same time, it introduces suction pressure to correct the condensation effect under high-pressure conditions, so that the safety boundary temperature can be dynamically and adaptively adjusted according to the actual operating conditions.

[0021] 5. This invention uses a hierarchical judgment logic with clear priorities to identify liquid hammer risk, freezing risk and condensation risk. It can ensure that emergency protection is triggered first in the most dangerous liquid hammer conditions. At the same time, it can clearly judge the risks of condensation and freezing, providing a basis for subsequent differentiated intervention strategies.

[0022] 6. This invention converts temperature deviation into EEV opening change rate according to exponential gain relationship, realizing fine throttling control with slow adjustment for small deviations and fast adjustment for large deviations; at the same time, it introduces exhaust pressure level coupling factor, which takes into account the compressor's operating safety and system anti-disturbance capability while ensuring anti-condensation effect.

[0023] 7. This invention dynamically calculates the lower limit of compressor frequency based on the refrigerant thermodynamic state factor, so that the frequency increase is positively correlated with the degree of liquid in the refrigerant. Under the risk of condensation, it actively raises the evaporation temperature and suction superheat to quickly remove surface moisture, while avoiding the energy waste or exceeding the compressor's allowable range caused by the frequency increasing indefinitely.

[0024] 8. When the EEV is reduced and the compressor frequency is increased but the surface temperature still cannot be raised above the safety boundary within the set time, the present invention actively starts the PTC, which can quickly eliminate the low-temperature condensation conditions that have been formed, and avoid excessive energy consumption or local overheating caused by blindly heating at full power.

[0025] 9. In high-risk operating conditions such as icing or liquid slugging, this invention no longer uses a gradual adjustment strategy. Instead, it uses the compressor characteristic curve and the exhaust temperature mapping function to directly back-calculate the EEV target opening degree and the compressor target frequency, achieving open-loop rapid strong intervention. This can bring the superheat and exhaust temperature back to the safe range in the shortest time, effectively curbing the continuous deterioration of icing or the irreversible damage to the compressor caused by liquid slugging.

[0026] 10. This invention calculates the minimum required PTC power based on thermal balance constraints, ensuring the physical accuracy and energy efficiency of the quantitative PTC power.

[0027] 11. This invention modularizes the entire anti-condensation and anti-icing method into four functional modules: risk assessment, early warning intervention, emergency protection, and recovery. Each module has clear logic and well-defined interfaces, facilitating integration and deployment in existing refrigeration unit control systems.

[0028] 12. This invention integrates the anti-condensation and anti-icing system into the actual refrigeration unit, enabling the unit to autonomously control the real-time thermal and humidity environment on the drive plate surface. Attached Figure Description

[0029] Figure 1 This is a flowchart of the present invention; Figure 2 This is a structural diagram of the refrigeration unit used in this invention; Among them, 01—gas separator; 02—compressor; 03—four-way valve; 04—condenser; 05—economizer; 06—drive plate piping; 07—drive plate; 08—electronic expansion valve; 09—evaporator. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0031] Embodiment 1 of the present invention proposes a method for preventing condensation and icing on the drive plate of a refrigeration unit, comprising: It should be noted that the refrigeration unit structure used in this invention is as follows: Figure 2 As shown, the refrigeration unit is a low-temperature variable frequency refrigerant chiller. Its basic structure includes: a compressor, a four-way valve, a condenser, an electronic expansion valve, an economizer (specifically a plate heat exchanger), an evaporator, and a gas separator (i.e., a vapor-liquid separator). These components are connected sequentially through refrigerant piping to form a closed refrigerant circulation loop. The drive board is a variable frequency drive board, which generates a large amount of heat during the variable frequency drive of the compressor, requiring effective heat dissipation.

[0032] The system acquires the superheat and instantaneous air dew point temperature; takes into account the hysteresis effect of changes in air humidity, and corrects the instantaneous air dew point temperature based on ambient temperature and humidity; calculates the refrigerant thermodynamic state factor based on the superheat; calculates the dynamic safety boundary temperature of the drive plate surface by combining the corrected instantaneous air dew point temperature, refrigerant thermodynamic state factor, and suction pressure; and determines whether there is a risk of condensation, freezing, or liquid slugging by the relationship between the drive plate surface temperature, the dynamic safety boundary temperature, and the freezing point temperature, as well as the relationship between the superheat and the set liquid slugging risk threshold. If there is a risk of condensation, the early warning intervention mode is activated: the opening change rate of the EEV is calculated based on the surface temperature of the drive plate and the compressor operating condition, and the opening of the EEV is reduced according to the opening change rate of the EEV; and the dynamic lower limit is calculated based on the refrigerant thermodynamic state factor, and the compressor frequency is increased to the dynamic lower limit; after reducing the opening of the EEV and increasing the compressor frequency to the dynamic lower limit, if the duration of the drive plate surface temperature being less than or equal to the dynamic safety boundary temperature exceeds the set first time, the PTC is activated. If there is a risk of icing or liquid slugging, the emergency protection mode is entered: the EEV target opening degree is calculated based on the set expected superheat, the compressor target frequency is calculated based on the exhaust temperature, and the PTC target power is calculated through thermal balance constraints. The EEV opening degree, compressor frequency and PTC power are adjusted to the EEV target opening degree, compressor target frequency and PTC target power respectively. If the surface temperature of the drive board exceeds the set recovery temperature for a set period of time, the EEV opening, compressor frequency, and PTC power will all be restored to their normal operating values.

[0033] It should be noted that this embodiment achieves precise differentiation and graded control of condensation, icing, and liquid slugging risks by introducing air humidity hysteresis correction, refrigerant thermodynamic state factor, and dynamic safety boundary temperature. Based on the risk type, differentiated EEV opening, compressor frequency, and PTC power are adjusted in a coordinated manner. This approach avoids excessive intervention in the early stages of condensation through fine-tuning, while providing strong protection during icing or liquid slugging. This effectively balances anti-condensation performance with system operational stability, improving the long-term reliability and safety of the refrigeration unit's drive board in harsh and humid environments.

[0034] In this preferred embodiment, the hysteresis effect of considering changes in air humidity is corrected based on ambient temperature and humidity to adjust the instantaneous dew point temperature of the air, specifically as follows: First based on ambient temperature and ambient humidity Calculate the instantaneous dew point temperature of air :

[0035] Considering the hysteresis effect of air humidity changes, the instantaneous air dew point temperature is obtained by adding the product of the rate of change of ambient humidity and a set first ambient thermal inertia coefficient, and then adding the product of the square of the rate of change of ambient temperature and a set second ambient thermal inertia coefficient. The formula is:

[0036] in, The first environmental thermal inertia coefficient is set; This is the set second environmental thermal inertia coefficient; when humidity rises rapidly, A significant increase triggered an early warning.

[0037] It should be noted that this embodiment corrects the dew point temperature by adjusting the rate of change of ambient temperature and humidity. This effectively compensates for the measurement deviation caused by sensor response lag and ambient thermal inertia, making the corrected dew point temperature closer to the true critical state of condensation on the microenvironment of the drive board surface, thereby improving the accuracy and lead time of risk prediction.

[0038] In this preferred embodiment, the calculation of the refrigerant thermodynamic state factor based on the superheat specifically involves: The superheat Intake temperature Subtract saturation temperature ,Right now ; Saturation temperature Based on the current inhalation pressure The parameters are obtained by referring to the table; it should be noted that parameters such as inhalation temperature, inhalation pressure, ambient temperature, and ambient pressure are directly obtained through sensor detection.

[0039] If the superheat is less than the liquid slugging risk threshold, the refrigerant thermodynamic state factor is 0; if the superheat is greater than or equal to the liquid slugging risk threshold but less than the rated superheat, the refrigerant thermodynamic state factor is equal to the difference between the superheat and the liquid slugging risk threshold divided by the difference between the rated superheat and the liquid slugging risk threshold; if the superheat is greater than or equal to the rated superheat, the refrigerant thermodynamic state factor is 1.

[0040] Refrigerant thermodynamic state factor The formula is as follows:

[0041] in, The liquid slamming risk threshold is set to 5K in this embodiment; The rated superheat is 10K in this embodiment.

[0042] It should be noted that in this embodiment, superheat is mapped to a continuous refrigerant thermodynamic state factor between 0 and 1. This factor can smoothly reflect the degree of refrigerant degradation as it approaches the liquid hammer boundary from its normal state, rather than simply making a binary judgment. This factor serves as a key input for subsequent calculations of the safety boundary and dynamic lower limit, enabling the control strategy to continuously perceive and progressively respond to the deterioration trend of the refrigerant state, thus avoiding system oscillations caused by sudden threshold changes.

[0043] In this preferred embodiment, the calculation of the dynamic safety boundary temperature of the drive plate surface by combining the corrected instantaneous dew point temperature of the air, the refrigerant thermodynamic state factor, and the suction pressure specifically involves: Subtract the refrigerant thermodynamic state factor from 1, and multiply the result by the set refrigerant low-quality penalty coefficient to obtain the refrigerant low-quality penalty item. The difference between the surface temperature of the drive board and the corrected instantaneous dew point temperature of the air is multiplied by the set speed coefficient, then multiplied by -1. The result of the multiplication is used as the exponent, and the natural base is used as the base. The result of the exponentiation is then multiplied by the set approach risk acceleration coefficient as the approach risk acceleration term. The pressure correction term is obtained by multiplying the normalized intake pressure by the set high-pressure condensation coefficient. The dynamic safety boundary temperature is obtained by superimposing the corrected instantaneous air dew point temperature, the refrigerant low-quality penalty term, the approach risk acceleration term, and the pressure correction term. The formula is as follows:

[0044] in, For a moment t Dynamic safety boundary temperature; For a moment t The surface temperature of the drive board; Normalized inhalation pressure; , , These are the low-quality refrigerant penalty coefficient, the approach risk acceleration coefficient, and the high-pressure condensation coefficient, all of which are greater than 0. The optimal coefficient values ​​are determined based on experience or by adjusting them through simulation or experimentation. The set speed coefficient; Among them, the penalty for low-quality refrigerant is: when the superheat is low, The small value indicates that the refrigerant is close to a liquid state, has a large latent heat, and is very prone to condensation, therefore the safety margin needs to be significantly increased.

[0045] The approach risk acceleration term indicates: when the surface temperature of the drive board... near At this point, the exponential term increases rapidly, forcing the control strategy to become more aggressive.

[0046] The pressure correction term indicates: Reflecting system load, condensation is more complete under high pressure, and the boundary should be adjusted appropriately.

[0047] It should be noted that this embodiment constructs a dynamic safety boundary temperature by integrating three factors: refrigerant low-quality penalty, approach risk acceleration, and high-pressure condensation correction. This not only considers the deteriorating effect of refrigerant liquid on evaporation temperature, but also uses an exponential term to characterize the nonlinear characteristics of the risk amplification when the surface temperature approaches the dew point. At the same time, it introduces suction pressure to correct the condensation effect under high-pressure conditions, so that the safety boundary temperature can be dynamically and adaptively adjusted according to the actual operating conditions, which significantly improves the scientific nature and on-site adaptability of the boundary determination.

[0048] In this preferred embodiment, the determination of whether there is a risk of condensation, freezing, or liquid hammer specifically involves: If the overheating is less than the set liquid slugging risk threshold, i.e. If so, it is judged as a risk of liquid impact; If there is no risk of liquid slugging, then determine whether the surface temperature of the drive board is less than or equal to the dynamic safety boundary temperature. If so, then determine whether the surface temperature of the drive board is greater than the freezing point temperature. If so, then it is considered a risk of condensation; otherwise, it is considered a risk of freezing. To mitigate the risk of condensation, Risk of icing.

[0049] It should be noted that this embodiment employs a hierarchical decision-making logic with clear priorities to identify liquid hammer risk, icing risk, and condensation risk. This ensures that emergency protection is triggered first under the most dangerous liquid hammer condition, preventing control resources from being occupied by lower-level risks. Simultaneously, clearly identifying condensation and icing risks provides a foundation for subsequent differentiated intervention strategies.

[0050] In this preferred embodiment, the calculation of the EEV opening change rate based on the drive board surface temperature and compressor operating conditions specifically involves: The difference between the dynamic safety boundary temperature and the drive board surface temperature is divided by the set reference temperature difference benchmark. The result of the division is used as the base, and the set second empirical gain coefficient is used as the exponent. The result of the exponent calculation is multiplied by the first empirical gain coefficient and then multiplied by -1 to obtain the EEV opening adjustment rate for temperature control. Multiplying the temperature-controlled EEV opening adjustment rate by the compressor operating condition coupling factor yields the EEV opening change rate. (The rate of change of opening is the derivative of opening with respect to time, and its unit is steps per second.) - ¹), the formula is:

[0051] in, , These are the first and second empirical gain coefficients, respectively. This is the set reference temperature difference standard; This is the compressor operating condition coupling factor; The compressor operating condition is the discharge pressure. If the discharge pressure is greater than the set maximum discharge pressure, the compressor operating condition coupling factor is the first coupling factor; if the discharge pressure is less than or equal to the set maximum discharge pressure and greater than the set minimum discharge pressure, the compressor operating condition coupling factor is the second coupling factor; if the discharge pressure is less than or equal to the set minimum discharge pressure, the compressor operating condition coupling factor is the third coupling factor. The first coupling factor is less than the second coupling factor, and the second coupling factor is less than the third coupling factor; Specifically, in this embodiment, the first coupling factor, the second coupling factor, and the third coupling factor are 0.5, 1, and 1.5, respectively; the formula for the compressor operating condition coupling factor is:

[0052] in, This refers to the exhaust pressure; , These are the set minimum and maximum discharge pressures, respectively. When the discharge pressure is high, the EEV closing speed is slowed down to prevent compressor overload; when the discharge pressure is low, the closing speed is accelerated to quickly increase superheat.

[0053] It should be noted that in this embodiment, the temperature deviation is converted into the EEV opening change rate according to the exponential gain relationship, so that the adjustment rate increases exponentially with the increase of temperature difference, realizing fine throttling control with slow adjustment for small deviations and fast adjustment for large deviations; at the same time, the exhaust pressure level coupling factor is introduced to reduce the valve adjustment rate to prevent system instability when the exhaust pressure is high (heavy load), and appropriately accelerate the response when the exhaust pressure is low (light load), so as to balance the compressor's operating safety and the system's anti-disturbance capability while ensuring the anti-condensation effect.

[0054] In this preferred embodiment, the calculation of the dynamic lower limit based on the refrigerant thermodynamic state factor specifically includes: Subtract the refrigerant thermodynamic state factor from 1, multiply the result by the set compensation coefficient, and add the result to the lower limit of the base compressor frequency to obtain the calculated dynamic lower limit. The formula is:

[0055] in, The lower limit of the base compressor frequency; The compensation coefficient is set; the lower the superheat, the higher the compressor frequency compensation is required to ensure that the exhaust temperature is sufficient to keep the drive plate temperature above the dynamic boundary.

[0056] It should be noted that in this embodiment, the lower limit of compressor frequency is dynamically calculated based on the refrigerant thermodynamic state factor, so that the frequency increase is positively correlated with the degree of liquid in the refrigerant. The worse the refrigerant state (the lower the factor), the higher the lower limit is raised. This actively raises the evaporation temperature and suction superheat to quickly remove surface moisture under the risk of condensation, while avoiding the energy waste caused by the frequency increasing indefinitely or exceeding the compressor's allowable range. This achieves a reasonable balance between safety and economy.

[0057] In this preferred embodiment, if the duration for which the surface temperature of the drive board is less than or equal to the dynamic safety boundary temperature exceeds a set first time... Then PTC will be started, specifically as follows: Subtracting the driver board surface temperature at the moment of PTC startup from the dynamic safety boundary temperature, multiplying by the PTC's thermal efficiency coefficient, and then multiplying by the set heating gain coefficient, yields the PTC startup power. The formula is as follows:

[0058] in, PTC power; The set heating gain coefficient; The thermal efficiency coefficient of PTC.

[0059] It should be noted that in this embodiment, when the EEV is reduced and the compressor frequency is increased, the surface temperature still cannot be raised to above the safety boundary within the set time. The PTC is actively activated and the heating power is calculated based on the real-time temperature difference and thermal efficiency coefficient. This can quickly eliminate the low-temperature condensation conditions that have been formed, and avoid excessive energy consumption or local overheating caused by blindly heating at full power.

[0060] In this preferred embodiment, the step of back-calculating the EEV target opening based on the set expected superheat and back-calculating the compressor target frequency based on the exhaust temperature specifically involves: By inputting the current condensing pressure, evaporating pressure, and set desired superheat into the compressor characteristic curve, the refrigerant mass flow rate is calculated. The EEV opening corresponding to the refrigerant mass flow rate is then obtained from a table and used as the target EEV opening. The formula is:

[0061] in, For EEV target opening; To calculate the refrigerant mass flow rate; This is the condensation pressure; Evaporation pressure; The set expected overheat level; This indicates that the EEV opening degree corresponding to the refrigerant mass flow rate can be derived by looking up the table.

[0062] By obtaining the mapping function between exhaust temperature and compressor target frequency through simulation or historical data, the minimum frequency at which the exhaust temperature exceeds the set exhaust temperature threshold can be derived as the compressor target frequency. The formula is as follows:

[0063] in, The target frequency for the compressor; The compressor frequency is the frequency. The exhaust temperature at that time; This is the set exhaust temperature threshold.

[0064] It should be noted that in high-risk conditions such as icing or liquid slugging, this embodiment no longer uses a gradual adjustment strategy. Instead, it directly uses the compressor characteristic curve and the discharge temperature mapping function to back-calculate the EEV target opening degree and the compressor target frequency, achieving open-loop rapid and strong intervention, allowing the system to cross the danger zone in one go. This method can bring superheat and discharge temperature back to the safe range in the shortest time, effectively curbing the continued deterioration of icing or irreversible damage to the compressor caused by liquid slugging, and improving the protection response speed under extreme conditions.

[0065] In this preferred embodiment, the calculation of the PTC target power through thermal balance constraints specifically involves: The thermal balance constraint is that the heat absorbed by the drive plate is equal to the heat released by the drive plate. Multiply the difference between the refrigerant temperature and the surface temperature of the drive plate by the refrigerant's convective heat transfer coefficient and then by the heat transfer area. Add the PTC power to the result of the multiplication to get the heat absorbed by the drive plate. Multiply the difference between the surface temperature of the drive plate and the ambient temperature by the air convection heat transfer coefficient and then by the heat transfer area. Add the result of the multiplication to the other heat losses of the drive plate to equal the heat released by the drive plate. If the PTC power that satisfies the thermal balance constraint is less than 0, then the PTC will not be started (i.e., the PTC power is 0); otherwise, the PTC power that satisfies the thermal balance constraint will be used as the PTC target power. The thermal equilibrium constraint is:

[0066] in, To absorb heat for the drive board; To dissipate heat from the driver board; The convective heat transfer coefficient of the refrigerant; The temperature of the refrigerant; For heat exchange area; PTC power; The convective heat transfer coefficient of air; Ambient temperature; Other heat losses of the drive board, including heat radiation and / or solid-state heat conduction, are set to fixed values ​​based on experimental calibration or experience.

[0067] It should be noted that physical limit constraints must also be met in emergency protection mode:

[0068] in, For compressor frequency; , These are the set lower and upper limits for the compressor frequency, respectively. EEV opening; , These are the set lower and upper limits of the EEV opening, respectively; The set upper limit for PTC power.

[0069] It should be noted that this embodiment calculates the required PTC power based on the thermal balance constraint that the heat absorbed and released by the drive board are strictly equal. It also incorporates two actual physical processes: refrigerant convection heat transfer and natural air cooling, ensuring the physical accuracy and energy efficiency of the PTC power calculation. When the required power for thermal balance is negative, PTC startup is actively prohibited, avoiding unnecessary energy consumption and preventing the negative effect of heating exacerbating the heat load when natural cooling is sufficient.

[0070] If the surface temperature of the driver board exceeds the set recovery temperature for a set second time... Then, the EEV opening, compressor frequency, and PTC power are all restored to their normal operating values, specifically as follows: PTC power decays to 0 according to a set exponential rate; The EEV opening slowly returns to its normal value at the set speed; The compressor frequency gradually decreases to the value corresponding to normal operation (i.e., the required storage temperature value) according to the set compensation.

[0071] Embodiment 2 of the present invention proposes a refrigeration unit drive board anti-condensation and icing system based on the method described in Embodiment 1 of the present invention, including a risk assessment module, an early warning intervention module, an emergency protection module, and a recovery module, specifically as follows: Risk assessment module: used to acquire superheat and instantaneous air dew point temperature; taking into account the hysteresis effect of air humidity changes, correcting the instantaneous air dew point temperature based on ambient temperature and humidity; calculating the refrigerant thermodynamic state factor based on the superheat; calculating the dynamic safety boundary temperature of the drive plate surface by combining the corrected instantaneous air dew point temperature, refrigerant thermodynamic state factor and suction pressure; determining whether there is a risk of condensation, freezing or liquid slugging by the relationship between the drive plate surface temperature and the dynamic safety boundary temperature and freezing point temperature, and the relationship between superheat and the set liquid slugging risk threshold. Early warning and intervention module: If condensation risk exists, it calculates the EEV opening change rate based on the drive plate surface temperature and compressor operating conditions, reduces the EEV opening according to the EEV opening change rate, and calculates the dynamic lower limit based on the refrigerant thermodynamic state factor, increasing the compressor frequency to the dynamic lower limit; after reducing the EEV opening and increasing the compressor frequency to the dynamic lower limit, if the duration of the drive plate surface temperature being less than or equal to the dynamic safety boundary temperature exceeds a set first time... Then PTC will be activated; Emergency protection module: If there is a risk of icing or liquid slugging, it will back-calculate the EEV target opening based on the set expected superheat, back-calculate the compressor target frequency based on the exhaust temperature, and calculate the PTC target power through thermal balance constraints, and adjust the EEV opening, compressor frequency and PTC power to the EEV target opening, compressor target frequency and PTC target power respectively. Recovery module: If the surface temperature of the drive board exceeds the set recovery temperature for a set period of time, the EEV opening, compressor frequency and PTC power will be restored to the values ​​corresponding to normal operation.

[0072] It should be noted that this embodiment modularizes the entire anti-condensation and anti-icing method into four functional modules: risk assessment, early warning intervention, emergency protection, and recovery. Each module has clear logic and well-defined interfaces, facilitating integration and deployment in existing refrigeration unit control systems, while also reducing the complexity and debugging costs of subsequent maintenance and upgrades.

[0073] Embodiment 3 of the present invention proposes a refrigeration unit that integrates the anti-condensation and anti-icing system of the refrigeration unit drive board described in Embodiment 2 of the present invention.

[0074] This embodiment integrates the anti-condensation and icing system proposed in Embodiment 2 into the actual refrigeration unit, enabling the unit to autonomously complete the real-time control of the thermal and humidity environment on the drive plate surface under complex conditions such as high temperature and humidity, variable operating conditions, and abnormal refrigerant status. This solves the problems of false alarms, missed alarms, and over-protection caused by traditional reliance on fixed temperature thresholds or single dehumidification methods.

[0075] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0076] Computer-readable storage media can be tangible devices capable of holding and storing instructions for use by an instruction execution device. Computer-readable storage media can be, for example—but not limited to—electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0077] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage media in the respective computing / processing device.

[0078] Computer program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing the status information of the computer-readable program instructions to implement various aspects of this disclosure.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for preventing condensation and icing on the drive plate of a refrigeration unit, characterized in that, include: Obtain the superheat and instantaneous dew point temperature of the air; taking into account the hysteresis effect of changes in air humidity, correct the instantaneous dew point temperature of the air based on the ambient temperature and humidity; calculate the refrigerant thermodynamic state factor based on the superheat. The superheat is the intake temperature minus the saturation temperature, and the saturation temperature is obtained by looking up a table based on the current intake pressure. If the superheat is less than the liquid slugging risk threshold, the refrigerant thermodynamic state factor is 0; if the superheat is greater than or equal to the liquid slugging risk threshold but less than the rated superheat, the refrigerant thermodynamic state factor is equal to the difference between the superheat and the liquid slugging risk threshold divided by the difference between the rated superheat and the liquid slugging risk threshold; if the superheat is greater than or equal to the rated superheat, the refrigerant thermodynamic state factor is 1. The dynamic safety boundary temperature of the drive plate surface is calculated by combining the corrected instantaneous dew point temperature of the air, the refrigerant thermodynamic state factor and the suction pressure: subtract the refrigerant thermodynamic state factor from 1, and multiply the result of the subtraction by the set refrigerant low quality penalty coefficient as the refrigerant low quality penalty item. The difference between the surface temperature of the drive board and the corrected instantaneous dew point temperature of the air is multiplied by the set speed coefficient, then multiplied by -1. The result of the multiplication is used as the exponent, and the natural base is used as the base. The result of the exponentiation is then multiplied by the set approach risk acceleration coefficient as the approach risk acceleration term. The pressure correction term is obtained by multiplying the normalized intake pressure by the set high-pressure condensation coefficient. The dynamic safety boundary temperature is obtained by superimposing the corrected instantaneous air dew point temperature, the refrigerant low quality penalty term, the approach risk acceleration term, and the pressure correction term. The presence of condensation risk, freezing risk, or liquid slugging risk is determined by the relationship between the surface temperature of the drive board and the dynamic safety boundary temperature and the freezing point temperature, as well as the relationship between the overheating and the set liquid slugging risk threshold. If there is a risk of condensation, the opening change rate of the EEV is calculated based on the surface temperature of the drive board and the operating conditions of the compressor, and the opening of the EEV is reduced according to the opening change rate of the EEV. Based on the refrigerant thermodynamic state factor, the dynamic lower limit is calculated, and the compressor frequency is increased to the dynamic lower limit. After reducing the EEV opening and increasing the compressor frequency to the dynamic lower limit, if the duration of the drive board surface temperature being less than or equal to the dynamic safety boundary temperature exceeds the set first time, the PTC is activated. If there is a risk of icing or liquid slugging, the EEV target opening is calculated based on the set expected superheat, the compressor target frequency is calculated based on the exhaust temperature, and the PTC target power is calculated through thermal balance constraints. The EEV opening, compressor frequency and PTC power are then adjusted to the EEV target opening, compressor target frequency and PTC target power, respectively. If the surface temperature of the drive board exceeds the set recovery temperature for a set period of time, the EEV opening, compressor frequency, and PTC power will all be restored to their normal operating values.

2. The method for preventing condensation and icing on the drive plate of a refrigeration unit according to claim 1, characterized in that: The hysteresis effect taking into account changes in air humidity is corrected for the instantaneous dew point temperature of the air based on ambient temperature and humidity, specifically as follows: The corrected instantaneous dew point temperature is obtained by adding the product of the rate of change of ambient humidity and the set first ambient thermal inertia coefficient to the instantaneous air dew point temperature, and then adding the product of the square of the rate of change of ambient temperature and the set second ambient thermal inertia coefficient.

3. The method for preventing condensation and icing on the drive plate of a refrigeration unit according to claim 1, characterized in that: The determination of whether there is a risk of condensation, freezing, or liquid hammer is as follows: If the superheat is less than the set liquid slugging risk threshold, it is judged as liquid slugging risk; If there is no risk of liquid slugging, determine whether the surface temperature of the drive board is less than or equal to the dynamic safety boundary temperature. If so, determine whether the surface temperature of the drive board is greater than the freezing point temperature. If so, determine the risk of condensation; otherwise, determine the risk of freezing.

4. The method for preventing condensation and icing on the drive plate of a refrigeration unit according to claim 1, characterized in that: The calculation of the EEV opening change rate based on the drive board surface temperature and compressor operating conditions is as follows: The difference between the dynamic safety boundary temperature and the drive board surface temperature is divided by the set reference temperature difference benchmark. The result of the division is used as the base, and the set second empirical gain coefficient is used as the exponent. The result of the exponent calculation is multiplied by the first empirical gain coefficient and then multiplied by -1 to obtain the EEV opening adjustment rate for temperature control. The compressor operating condition is the discharge pressure. If the discharge pressure is greater than the set maximum discharge pressure, then the compressor operating condition coupling factor is the first coupling factor. If the discharge pressure is less than or equal to the set maximum discharge pressure and greater than the set minimum discharge pressure, then the compressor operating condition coupling factor is the second coupling factor. If the discharge pressure is less than or equal to the set minimum discharge pressure, the compressor operating condition coupling factor is the third coupling factor. The first coupling factor is less than the second coupling factor, and the second coupling factor is less than the third coupling factor; Multiply the temperature-controlled EEV opening adjustment rate by the compressor operating condition coupling factor to obtain the EEV opening change rate.

5. The method for preventing condensation and icing on the drive plate of a refrigeration unit according to claim 1, characterized in that: The dynamic lower limit calculated based on the refrigerant thermodynamic state factor is specifically as follows: Subtract the refrigerant thermodynamic state factor from 1, multiply the result by the set compensation coefficient, and add the result to the lower limit of the base compressor frequency to calculate the dynamic lower limit.

6. The method for preventing condensation and icing on the drive plate of a refrigeration unit according to claim 1, characterized in that: If the duration of the driver board surface temperature being less than or equal to the dynamic safety boundary temperature exceeds a set first time, then the PTC will be activated, specifically: The power required to start the PTC is obtained by subtracting the surface temperature of the drive board at the moment of PTC startup from the dynamic safety boundary temperature, multiplying by the thermal efficiency coefficient of the PTC, and then multiplying by the set heating gain coefficient.

7. The method for preventing condensation and icing on the drive plate of a refrigeration unit according to claim 1, characterized in that: The process of inferring the EEV target opening based on the set expected superheat and inferring the compressor target frequency based on the exhaust temperature is as follows: Substitute the current condensing pressure, evaporating pressure, and set desired superheat into the compressor characteristic curve to back-calculate the refrigerant mass flow rate. Then, by looking up the table, obtain the EEV opening corresponding to the refrigerant mass flow rate as the EEV target opening. By obtaining the mapping function between exhaust temperature and compressor target frequency through simulation or historical data, the minimum frequency at which the exhaust temperature exceeds the set exhaust temperature threshold can be deduced as the compressor target frequency.

8. The method for preventing condensation and icing on the drive plate of a refrigeration unit according to claim 1, characterized in that: The calculation of the PTC target power through thermal balance constraints is specifically as follows: The thermal balance constraint is that the heat absorbed by the drive plate is equal to the heat released by the drive plate. Multiply the difference between the refrigerant temperature and the surface temperature of the drive plate by the refrigerant's convective heat transfer coefficient and then by the heat transfer area. Add the PTC power to the result of the multiplication to get the heat absorbed by the drive plate. Multiply the difference between the surface temperature of the drive plate and the ambient temperature by the air convection heat transfer coefficient and then by the heat transfer area. Add the result of the multiplication to the other heat losses of the drive plate to equal the heat released by the drive plate. Other heat losses include heat radiation and / or solid thermal conductivity. If the PTC power that satisfies the thermal balance constraint is less than 0, the PTC will not be started; otherwise, the PTC power that satisfies the thermal balance constraint will be used as the PTC target power.

9. A refrigeration unit drive board anti-condensation and anti-icing system based on the method of any one of claims 1-8, comprising a risk assessment module, an early warning intervention module, an emergency protection module, and a recovery module, characterized in that: Risk assessment module: used to acquire superheat and instantaneous air dew point temperature; taking into account the hysteresis effect of air humidity changes, correcting the instantaneous air dew point temperature based on ambient temperature and humidity; calculating the refrigerant thermodynamic state factor based on the superheat; calculating the dynamic safety boundary temperature of the drive plate surface by combining the corrected instantaneous air dew point temperature, refrigerant thermodynamic state factor and suction pressure; determining whether there is a risk of condensation, freezing or liquid slugging by the relationship between the drive plate surface temperature and the dynamic safety boundary temperature and freezing point temperature, and the relationship between superheat and the set liquid slugging risk threshold. Early warning and intervention module: If there is a risk of condensation, it calculates the opening change rate of EEV based on the surface temperature of the drive board and the operating conditions of the compressor, and reduces the opening of EEV according to the opening change rate of EEV. Based on the refrigerant thermodynamic state factor, the dynamic lower limit is calculated, and the compressor frequency is increased to the dynamic lower limit. After reducing the EEV opening and increasing the compressor frequency to the dynamic lower limit, if the duration of the drive board surface temperature being less than or equal to the dynamic safety boundary temperature exceeds the set first time, the PTC is activated. Emergency protection module: If there is a risk of icing or liquid slugging, it will back-calculate the EEV target opening based on the set expected superheat, back-calculate the compressor target frequency based on the exhaust temperature, and calculate the PTC target power through thermal balance constraints, and adjust the EEV opening, compressor frequency and PTC power to the EEV target opening, compressor target frequency and PTC target power respectively. Recovery module: If the surface temperature of the drive board exceeds the set recovery temperature for a set period of time, the EEV opening, compressor frequency and PTC power will be restored to the values ​​corresponding to normal operation.

10. A refrigeration unit, characterized in that, The refrigeration unit drive board anti-condensation and icing system described in claim 9 is integrated.

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