A Model-Based Prediction-Based CO2 Heat Pump Defrosting Control Method and System

Abstract

This invention relates to the field of heat pump control technology, and discloses a model-predictive CO2 heat pump defrosting control method and system. The method includes: collecting CO2 heat pump heating operation data; determining a frosting impact assessment coefficient by the deviation between the actual and theoretical heat exchange temperature difference; identifying the frosting deterioration period based on coefficient changes; and generating a defrosting start indicator by combining the inflection point of the return water temperature change rate. Based on this indicator, the valve opening degree and compressor frequency are sequentially configured to form a corresponding modulation sequence, driving the actuators and switching the defrosting mode when the exhaust pressure reaches the transition equilibrium point. Subsequently, a defrosting progress index is determined based on the temporal relationship between the extreme point of the heat exchanger outlet temperature and the saturation point of the compressor suction pressure. Finally, parameters are adjusted according to this index to generate a heating recovery command, achieving precise defrosting control and heating recovery. This invention can improve the efficiency of model-predictive CO2 heat pump defrosting control.

Description

Technical Field

[0001] This invention relates to the field of heat pump control technology, and in particular to a CO2 heat pump defrosting control method and system based on model prediction. Background Technology

[0002] In practical applications of CO2 heat pumps, defrosting control is a core element in ensuring their low-temperature heating efficiency. Existing defrosting control technologies often employ fixed threshold triggering or empirical parameter adjustments, failing to quantitatively assess the impact of frosting based on real-time data from heat pump operation. They also cannot accurately identify critical stages of frosting deterioration, leading to issues such as starting defrosting too early or too late. Initiating defrosting too early results in unnecessary waste of heat pump energy and reduces overall system heating efficiency. Initiating defrosting too late causes excessive frosting on the heat exchanger, significantly reducing heat exchange efficiency and significantly weakening the heat pump's heating capacity, making it difficult to meet heating demands in low-temperature environments. Furthermore, existing technologies lack dynamic adaptability in parameter adjustments during the defrosting process; valve opening and compressor frequency adjustments are disconnected from actual system pressure and temperature conditions, further impacting defrosting effectiveness.

[0003] Existing CO2 heat pump defrosting control technology also has significant shortcomings in the defrosting process and heating recovery phases. It cannot accurately define different stages of the defrosting process based on changes in core system operating indicators. Defrosting mode switching and parameter adjustments are often rigidly executed, easily leading to drastic fluctuations in system pressure and temperature, affecting the stability of heat pump operation. During the heating recovery phase, existing technologies often directly reset parameters to fixed values ​​without considering the system's operating state after defrosting. This can easily cause refrigerant circulation disorder due to sudden parameter changes, and there is a lack of assessment of parameter adjustment convergence. The timing of heating recovery lacks scientific basis, resulting in poor transition between defrosting and heating mode switching. The system requires a long time to return to stable heating. Overall, the accuracy, stability, and efficiency of defrosting control are insufficient to meet practical application requirements. Summary of the Invention

[0004] This invention provides a model-predictive CO2 heat pump defrosting control method and system, the main purpose of which is to solve the problem of low efficiency in model-predictive CO2 heat pump defrosting control.

[0005] To achieve the above objectives, the present invention provides a model-predictive CO2 heat pump defrosting control method, comprising: Collect heating operation data of the target process, and determine the frosting impact assessment coefficient of the target process based on the degree of deviation between the actual heat exchange temperature difference and the theoretical heat exchange temperature difference of the heating operation data; Based on the changing trend of the frost impact assessment coefficient, the frost deterioration period of the target process is identified, and within the frost deterioration period, the turning point where the rate of change of return water temperature in the heating operation data changes from positive to negative is located, thereby obtaining the defrosting start indicator of the target process. Based on the status parameters of the defrost start indicator, the opening degree of key valves and the frequency of the compressor in the target process are configured sequentially to obtain the valve modulation sequence and compressor modulation sequence of the target process; The actuator of the target process is driven according to the valve modulation sequence and the compressor modulation sequence, and the defrosting mode of the target process is switched when the exhaust pressure of the actuator reaches the transition equilibrium point of the target process. Based on the defrosting mode, the defrosting progress index of the target process is determined according to the temporal relationship between the time of the extreme point of the heat exchanger outlet temperature in the target process and the time when the compressor suction pressure falls to the saturation pressure value corresponding to the current ambient temperature in the target process. Based on the defrosting progress index, the opening degree of key valves and compressor frequency of the target process are adjusted to obtain the heating recovery command of the target process.

[0006] In a preferred embodiment, the step of collecting heating operation data of the target process and determining the frosting impact assessment coefficient of the target process based on the deviation between the actual heat exchange temperature difference and the theoretical heat exchange temperature difference of the heating operation data includes: The difference between the outdoor heat exchanger inlet temperature and the outdoor heat exchanger outlet temperature in the heating operation data is taken as the actual heat exchange temperature difference of the target process. The average difference between the outdoor heat exchanger inlet temperature and the outdoor heat exchanger outlet temperature in the heating operation data is taken as the theoretical heat exchange temperature difference of the target process. The difference between the actual heat exchange temperature difference and the theoretical heat exchange temperature difference is taken as the temperature difference deviation value of the target process; The ratio of the temperature difference deviation to the theoretical heat exchange temperature difference is used as the frost impact evaluation coefficient for the target process.

[0007] In a preferred embodiment, the step of identifying the frosting deterioration period of the target process based on the changing trend of the frosting impact assessment coefficient, and locating the turning point where the rate of change of return water temperature in the heating operation data changes from positive to negative within the frosting deterioration period, to obtain the defrosting start indicator of the target process, includes: By monitoring the value of the frost impact assessment coefficient within the sampling period during the target process, the frost assessment change sequence of the target process is obtained; The frost impact assessment coefficient of the current monitoring period in the frost assessment change sequence is compared with the frost impact assessment coefficient of the previous monitoring period: when the comparison results of the continuous monitoring periods in the target process all indicate that the frost impact assessment coefficient of the current monitoring period is greater than the frost impact assessment coefficient of the previous monitoring period, the continuous monitoring period is defined as the frost deterioration period of the target process. The rate of change and the corresponding direction of the return water temperature are obtained based on the initial and final values ​​of the return water temperature in the heating operation data during the frosting deterioration period. When the rate of change of return water temperature in the current monitoring cycle is negative and the rate of change in the previous monitoring cycle is positive, the current monitoring cycle is positioned as the turning point of the target process. Using the edge of the inflection point as a trigger signal, the defrosting start indicator of the target process is obtained.

[0008] In a preferred embodiment, the step of sequentially configuring the opening degree of key valves and the frequency of the compressor in the target process based on the state parameters of the defrost start indicator to obtain the valve modulation sequence and compressor modulation sequence of the target process includes: Based on the defrosting start identifier, the current opening degree of the key valve in the target process is used as the benchmark, and the time difference sign of the frosting influence evaluation coefficient in the target process is used as the step direction of the target process; The opening of the current key valve is adjusted in unit steps according to the step direction, and the change response of the heat exchanger outlet temperature in the target process is detected: if the direction of the change response is consistent with the step direction, the current step direction of the target process will be retained; if the direction of the change response is inconsistent with the step direction, the current step direction of the target process will be reversed. Based on the direction of the change response, the opening change direction of the heat exchanger outlet temperature in an upward trend is iteratively screened, and the cumulative adjustment in the opening change direction is taken as the defrosting opening target value of the target process. The intermediate opening sequence required to reach the target defrost opening value is used as the valve modulation sequence for the target process; The compressor modulation sequence of the target process is determined based on the current exhaust pressure and intake pressure of the target process; The valve modulation sequence and the compressor modulation sequence are concatenated in chronological order to obtain the valve modulation sequence and compressor modulation sequence of the target process.

[0009] In a preferred embodiment, determining the compressor modulation sequence of the target process based on the current exhaust pressure and intake pressure of the target process includes: The process of reducing the compressor frequency is decomposed into various frequency pulse actions of the target process, which include a frequency descent step and a frequency holding step. The amplitude of the frequency descent step is determined by the sign of the pressure deviation between the exhaust pressure and the saturation pressure value corresponding to the current ambient temperature during the target process: if the sign of the pressure deviation is positive, the amplitude of the frequency descent step is set to a unit basic step size; if the sign of the pressure deviation is negative, the amplitude of the frequency descent step is set to zero. The duration of the frequency holding step is determined based on the fluctuation range of the compressor suction pressure during the target process: when the suction pressure fluctuation range at the end of the frequency holding step is less than the fluctuation range at the end of the preceding holding step in the target process, the current holding step of the target process ends; when the suction pressure fluctuation range at the end of the frequency holding step is greater than the fluctuation range at the end of the preceding holding step, the duration of the current holding step of the target process is set to a basic time unit. During the continuous sampling period of the target process, if the fluctuation amplitude at the end of the frequency holding step is smaller than the fluctuation amplitude of the preceding holding step, and the fluctuation amplitude is smaller than the absolute value of the heat exchanger outlet temperature change rate in the target process, the current compressor frequency of the target process is taken as the defrosting frequency target value of the target process. The various frequency pulse actions are connected in chronological order to form a compressor modulation sequence for the target process.

[0010] In a preferred embodiment, driving the actuator of the target process according to the valve modulation sequence and the compressor modulation sequence, and switching the defrosting mode of the target process when the exhaust pressure of the actuator reaches the transition equilibrium point of the target process, includes: According to the opening modulation step size in the valve modulation sequence and the frequency modulation step size in the compressor modulation sequence, the execution component of the target process is adjusted step by step to obtain the dynamic modulation sequence of the target process; Based on the dynamic modulation sequence, monitor the compressor discharge pressure and the corresponding pressure-time change curve of the target process; Calculate the fluctuation attenuation coefficient of exhaust pressure in adjacent monitoring cycles during the target process based on the pressure-time change curve. When the fluctuation attenuation coefficient shows a monotonically decreasing trend during the continuous monitoring period of the target process, the exhaust pressure of the target process is calibrated as the transition equilibrium exhaust pressure of the target process. When the compressor discharge pressure reaches the transition equilibrium discharge pressure, the refrigerant flow direction of the target process is switched to obtain the defrosting mode of the target process.

[0011] In a preferred embodiment, the formula for calculating the fluctuation attenuation coefficient includes: in, For the first The dimensionless fluctuation attenuation coefficient for each monitoring period For sampling period index, The exhaust pressure for the current monitoring period. The exhaust pressure from the previous monitoring period. The exhaust pressure is from the first two monitoring cycles. For the duration of the monitoring period, For the width of the history window, This is the position index within the historical fluctuation window.

[0012] In a preferred embodiment, the step of determining the defrosting progress index of the target process based on the defrosting mode, according to the temporal relationship between the time of the extreme point of the heat exchanger outlet temperature in the target process and the time when the compressor suction pressure falls to the saturation pressure value corresponding to the current ambient temperature in the target process, includes: Based on the defrosting mode, record the peak operating temperature of the heat exchanger outlet and the corresponding peak time during the target process; The moment when the compressor suction pressure changes from decreasing to increasing during the target process is taken as the pressure recovery moment of the target process. When the peak time is earlier than the pressure recovery time, the initial defrosting phase indicator of the target process is obtained; When the peak moment and the pressure recovery moment are both recorded in the target process record, the defrosting end point identifier of the target process is obtained; The initial defrosting indicator and the final defrosting indicator are combined to form the defrosting progress index of the target process.

[0013] In a preferred embodiment, adjusting the opening degree of key valves and compressor frequency of the target process according to the defrosting progress index to obtain the heating recovery command of the target process includes: The opening degree of the key valve corresponding to the initial defrosting indicator in the defrosting progress index is taken as the recovery target opening degree of the target process, and the corresponding compressor frequency is taken as the recovery target frequency of the target process. Based on the defrosting end-of-defrosting indicator in the defrosting progress index, the opening degree of the key valve and the compressor frequency are successively approximated to the recovery target opening degree and the recovery target frequency to obtain the test sequence of the target process; When the real-time deviation value in each consecutive period of the test sequence is not greater than the previous deviation value, the heating recovery command of the target process is obtained.

[0014] To address the aforementioned problems, the present invention also provides a model-predictive CO2 heat pump defrosting control system, the system comprising: The frosting assessment module collects heating operation data of the target process and determines the frosting impact assessment coefficient of the target process based on the degree of deviation between the actual heat exchange temperature difference and the theoretical heat exchange temperature difference in the heating operation data. The defrosting start-up module identifies the defrosting deterioration period of the target process based on the changing trend of the defrosting impact assessment coefficient, and locates the turning point where the rate of change of return water temperature in the heating operation data changes from positive to negative within the defrosting deterioration period, thereby obtaining the defrosting start-up identifier of the target process. The modulation sequence module sequentially configures the opening degree of key valves and the frequency of the compressor in the target process based on the state parameters of the defrost start identifier, thereby obtaining the valve modulation sequence and compressor modulation sequence of the target process; The defrosting module is switched to drive the actuator of the target process according to the valve modulation sequence and the compressor modulation sequence, and the defrosting mode of the target process is switched when the exhaust pressure of the actuator reaches the transition equilibrium point of the target process. The progress indicator module, based on the defrosting mode, determines the defrosting progress indicator of the target process according to the temporal relationship between the time of the extreme point of the heat exchanger outlet temperature in the target process and the time when the compressor suction pressure falls to the saturation pressure value corresponding to the current ambient temperature in the target process. The heating recovery module adjusts the opening degree of key valves and compressor frequency of the target process according to the defrosting progress index to obtain the heating recovery command of the target process.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This technology achieves quantitative assessment of the impact of frosting and accurate identification of the frosting deterioration period through precise acquisition and analysis of CO2 heat pump heating operation data. It determines the defrosting initiation timing based on the trend characteristics of the return water temperature change rate, providing a scientific and quantitative basis for defrosting initiation and significantly improving the accuracy of defrosting initiation timing selection. Simultaneously, the technology designs a dynamic modulation sequence generation method for valve opening and compressor frequency, combining real-time feedback of system pressure and temperature for step size adjustment and parameter iterative optimization. This achieves refined and dynamic adaptability of the actuator adjustment during the defrosting process, ensuring the stability of system operating parameters during the defrosting phase, effectively improving the execution efficiency of defrosting operations, and ensuring that the defrosting process is always highly consistent with the actual operating state of the heat pump system.

[0016] 2. This technology divides the defrosting process into stages by monitoring changes in core operating indicators, forming a comprehensive index that fully reflects the defrosting progress. This provides clear stage guidance for switching defrosting modes and adjusting parameters, achieving refined control of the defrosting process. During the heating recovery stage, the stable operating parameters at the initial stage of defrosting are used as the recovery target. A test sequence is generated through successive approximation adjustments, and the timing of heating recovery is determined based on the convergence of parameter adjustments. This makes parameter adjustments for heating recovery more targeted, achieving a smooth transition from defrosting mode to heating mode. This effectively shortens the system's stabilization time for heating recovery, ensuring the continuity and efficiency of the heat pump system's heating operation. It comprehensively improves the overall precision and automation level of CO2 heat pump defrosting control, ensuring the heating performance of the heat pump system in low-temperature environments. Attached Figure Description

[0017] Figure 1 A schematic flowchart of a model-predictive CO2 heat pump defrosting control method provided in an embodiment of the present invention; Figure 2 A functional block diagram of a model-predictive CO2 heat pump defrosting control system provided in an embodiment of the present invention; The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0019] This application provides a model-predictive CO2 heat pump defrosting control method. The executing entity of the model-predictive CO2 heat pump defrosting control method includes, but is not limited to, at least one of the following electronic devices that can be configured to execute the method provided in this application: a server, a terminal, etc. In other words, the model-predictive CO2 heat pump defrosting control method can be executed by software or hardware installed on a terminal device or a server device. The server includes, but is not limited to, a single server, a server cluster, a cloud server, or a cloud server cluster. The server can be an independent server or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, content delivery networks (CDNs), and big data and artificial intelligence platforms.

[0020] Reference Figure 1The diagram shown is a schematic flowchart of a model-predictive CO2 heat pump defrosting control method according to an embodiment of the present invention. In this embodiment, the model-predictive CO2 heat pump defrosting control method includes: In this invention embodiment, when collecting heating operation data of the target process and determining the frosting impact assessment coefficient of the target process based on the deviation between the actual heat exchange temperature difference and the theoretical heat exchange temperature difference of the heating operation data, the specific purpose is as follows: The difference between the outdoor heat exchanger inlet temperature and the outdoor heat exchanger outlet temperature in the heating operation data is taken as the actual heat exchange temperature difference of the target process. The average difference between the outdoor heat exchanger inlet temperature and the outdoor heat exchanger outlet temperature in the heating operation data is taken as the theoretical heat exchange temperature difference of the target process. The difference between the actual heat exchange temperature difference and the theoretical heat exchange temperature difference is taken as the temperature difference deviation value of the target process; The ratio of the temperature difference deviation to the theoretical heat exchange temperature difference is used as the frost impact evaluation coefficient for the target process.

[0021] Specifically, the outdoor heat exchanger inlet temperature and outdoor heat exchanger outlet temperature values ​​for the corresponding monitoring period are extracted from the heating operation data of the target process. A subtraction operation is performed on the two sets of temperature values ​​under the same monitoring period, directly subtracting the outdoor heat exchanger outlet temperature from the specific value of the outdoor heat exchanger inlet temperature. The specific value obtained after this subtraction operation is the actual heat exchange temperature difference of the target process under the monitoring period.

[0022] Specifically, the outdoor heat exchanger inlet temperature and outdoor heat exchanger outlet temperature values ​​corresponding to all monitoring cycles within the entire monitoring period are extracted from the heating operation data of the target process. The outdoor heat exchanger inlet temperature and outlet temperature for each monitoring cycle are subtracted to obtain the heat exchanger inlet and outlet temperature difference for each monitoring cycle within the entire monitoring period.

[0023] Specifically, the actual heat exchange temperature difference value determined under the corresponding monitoring period of the target process is extracted, and the theoretical heat exchange temperature difference value of the target process calculated is also extracted. The actual heat exchange temperature difference value of the monitoring period is used as the minuend, and the theoretical heat exchange temperature difference value is used as the subtrahend, and the subtraction operation is performed.

[0024] Specifically, the temperature difference deviation value determined under the corresponding monitoring period of the target process is extracted, and the theoretical heat exchange temperature difference value of the target process is also extracted. The specific value of the temperature difference deviation value under the monitoring period is used as the dividend, and the specific value of the theoretical heat exchange temperature difference is used as the divisor. The division operation is then performed.

[0025] Furthermore, for each monitoring cycle, temperature values ​​are extracted and subtracted in this manner to obtain the actual heat exchange temperature difference for the corresponding cycle. This ensures that the actual heat exchange temperature difference corresponds uniquely to the inlet and outlet temperatures of the outdoor heat exchanger for the corresponding monitoring cycle, thus fully restoring the actual heat exchange temperature difference of the heat exchanger within that cycle.

[0026] Furthermore, all calculated temperature difference values ​​are collected throughout the entire time period. These values ​​are then summed to obtain the total sum of all temperature differences. This total sum is then divided by the total number of temperature differences involved in the calculation throughout the entire monitoring period, which is the total number of monitoring cycles. The specific numerical result obtained through this method is the theoretical heat exchange temperature difference of the target process. This value comprehensively reflects the overall average level of the inlet and outlet temperature difference of the heat exchanger throughout the entire monitoring period.

[0027] Furthermore, the actual heat exchange temperature difference is directly subtracted from the theoretical heat exchange temperature difference. The specific value obtained after this subtraction operation is the temperature difference deviation of the target process in the monitoring period. This value directly reflects the specific degree of deviation of the actual heat exchange temperature difference from the theoretical heat exchange temperature difference in the corresponding monitoring period. The calculation is completed in this way for each monitoring period to obtain the temperature difference deviation value of the corresponding period.

[0028] Furthermore, the temperature difference deviation is directly divided by the theoretical heat exchange temperature difference. The specific value obtained after this division operation is the frost impact assessment coefficient of the target process in this monitoring period. This value correlates the temperature difference deviation with the theoretical heat exchange temperature difference, and quantifies the actual impact of the heat exchange temperature difference deviation on the frost formation of the target process. The calculation is completed in this way for each monitoring period to obtain the frost impact assessment coefficient for the corresponding period.

[0029] In summary, using the difference between the inlet and outlet temperatures of the outdoor heat exchanger as the actual heat exchange temperature difference can directly and accurately reflect the actual heat exchange temperature difference of the outdoor heat exchanger during the target process. This closely matches the actual heat exchange state of the heat exchanger during CO2 heat pump heating operation. Using this value as the basic data for frost assessment ensures that subsequent frost-related judgments are always based on the actual operating parameters of the heat pump system, avoiding frost assessment deviations caused by distorted basic data. This provides a core, realistic basis for calculating the frost impact assessment coefficient.

[0030] In summary, using the average difference between the inlet and outlet temperatures of the outdoor heat exchanger as the theoretical heat exchange temperature difference can comprehensively reflect the benchmark level of the heat exchange temperature difference of the heat pump system under normal heating conditions and without significant frost during the target process. This value integrates heat exchange temperature difference data over the entire period, eliminates the randomness of single monitoring data, and provides a stable and objective reference standard for judging whether the actual heat exchange temperature difference deviates due to frost. This allows subsequent temperature difference deviation judgments to have a unified comparison basis that fits the normal operating conditions of the system.

[0031] In summary, using the difference between the actual heat exchange temperature difference and the theoretical heat exchange temperature difference as the temperature difference deviation value can intuitively and quantitatively reflect the degree of deviation of the actual heat exchange temperature difference of the heat exchanger from the normal operating benchmark of the system. The sign and magnitude of this value can directly reflect the trend and magnitude of the impact of frost on the heat exchanger's heat exchange effect, transforming the abstract impact of frost into a specific numerical difference, making the interference of frost on the heat exchange process clearly apparent, and becoming a key intermediate value for further quantifying the degree of frost impact.

[0032] In summary, using the ratio of the temperature difference deviation to the theoretical heat exchange temperature difference as the frost impact assessment coefficient enables a dimensionless quantitative assessment of the degree of frost impact. This eliminates the interference of the basic value of the heat exchange temperature difference on the judgment of the frost impact, making the degree of frost impact under different operating conditions and monitoring cycles comparable. This coefficient can accurately and objectively reflect the actual proportion of the impact of frost on the heat exchanger's heat exchange efficiency, providing a quantitative core judgment indicator for subsequent identification of the frost deterioration period and determination of the defrosting start time. This transforms the defrosting control of CO2 heat pumps from empirical judgment to precise judgment based on quantitative indicators, improving the scientificity and accuracy of defrosting control.

[0033] In this invention embodiment, the step of identifying the frosting deterioration period of the target process based on the changing trend of the frosting impact assessment coefficient, and locating the turning point where the rate of change of return water temperature in the heating operation data changes from positive to negative within the frosting deterioration period to obtain the defrosting start indicator of the target process, is specifically used for: By monitoring the value of the frost impact assessment coefficient within the sampling period during the target process, the frost assessment change sequence of the target process is obtained; The frost impact assessment coefficient of the current monitoring period in the frost assessment change sequence is compared with the frost impact assessment coefficient of the previous monitoring period: when the comparison results of the continuous monitoring periods in the target process all indicate that the frost impact assessment coefficient of the current monitoring period is greater than the frost impact assessment coefficient of the previous monitoring period, the continuous monitoring period is defined as the frost deterioration period of the target process. The rate of change and the corresponding direction of the return water temperature are obtained based on the initial and final values ​​of the return water temperature in the heating operation data during the frosting deterioration period. When the rate of change of return water temperature in the current monitoring cycle is negative and the rate of change in the previous monitoring cycle is positive, the current monitoring cycle is positioned as the turning point of the target process. Using the edge of the inflection point as a trigger signal, the defrosting start indicator of the target process is obtained.

[0034] Specifically, each sampling period of the target process is tracked cycle by cycle. Within each sampling period, the specific value of the frost impact assessment coefficient calculated in that period is accurately extracted. According to the time sequence of the sampling periods, the frost impact assessment coefficient values ​​corresponding to all sampling periods are arranged in order to form an ordered numerical sequence.

[0035] Specifically, the frost impact assessment coefficient value corresponding to the current monitoring period is extracted from the frost assessment change sequence, and the frost impact assessment coefficient value corresponding to the previous monitoring period is also extracted. The two sets of values ​​are compared to clarify the size relationship between the current monitoring period value and the previous monitoring period value. The comparison operation with the previous monitoring period value is performed sequentially for each subsequent monitoring period in this manner.

[0036] Specifically, within the defined frosting deterioration period, the specific value of the return water temperature corresponding to the start time of the frosting deterioration period is extracted from the heating operation data as the initial value of the return water temperature, and the specific value of the return water temperature corresponding to the end time of the frosting deterioration period is extracted as the final value of the return water temperature. Combining the overall duration of the frosting deterioration period, the trend of return water temperature change is judged by the changes in the values ​​of the initial and final values.

[0037] Specifically, during the period of frost deterioration, the direction of the rate of change of return water temperature for each monitoring cycle is checked cycle by cycle, and the direction of the rate of change of return water temperature corresponding to the current monitoring cycle is extracted. At the same time, the direction of the rate of change of return water temperature corresponding to the previous monitoring cycle is also extracted.

[0038] Specifically, the time edge of the identified inflection point is used as the core trigger signal. This edge is the time node at which the monitoring cycle corresponding to the inflection point begins. When the system detects the signal trigger of this time edge, it directly generates the defrost start identifier of the target process. This defrost start identifier is a clear start trigger signal.

[0039] Furthermore, this sequence is a frost assessment change sequence for the target process. The value at each position in the sequence corresponds one-to-one with the corresponding sampling period, fully presenting the numerical change of the frost impact assessment coefficient as the sampling period progresses, ensuring that the sequence can accurately reflect the dynamic change characteristics of the frost impact assessment coefficient in the time dimension.

[0040] Furthermore, when the comparison results of multiple consecutive monitoring cycles show that the frost impact assessment coefficient of the current monitoring cycle is greater than that of the previous monitoring cycle, this continuous monitoring cycle is defined as the frost deterioration period of the target process. The frost deterioration period begins with the first monitoring cycle in which the continuous comparison results meet the conditions and ends with the last monitoring cycle in which the continuous comparison results meet the conditions.

[0041] Furthermore, the direction of the rate of change of return water temperature is determined by the trend of change. If the termination value is greater than the initial value, the direction of the rate of change is positive; if the termination value is less than the initial value, the direction of the rate of change is negative. At the same time, the specific situation of the rate of change of return water temperature is determined by combining the duration, so as to obtain the rate of change of return water temperature and its corresponding direction during the frosting deterioration period.

[0042] Furthermore, when the verification result shows that the direction of the rate of change of the return water temperature in the current monitoring cycle is negative, and the direction of the rate of change of the return water temperature in the previous monitoring cycle is positive, the current monitoring cycle that meets the conditions is directly determined as the defrosting-related turning point of the target process. This turning point is the key monitoring cycle in which the direction of the rate of change of the return water temperature changes from positive to negative during the period of frosting deterioration, and it is the core node for judging the timing of defrosting initiation.

[0043] Furthermore, the generation of the indicator is precisely linked to the time edge of the turning point, ensuring that the defrosting start indicator is generated in a timely manner at the critical node when the direction of the return water temperature change rate changes from positive to negative, providing a clear trigger basis for subsequent defrosting-related operations.

[0044] In summary, monitoring the frost impact assessment coefficient values ​​within the sampling period of the target process and forming a frost assessment change sequence can transform discrete single-cycle frost impact quantitative data into a continuous sequence arranged in chronological order. This fully presents the dynamic change trajectory of the frost impact assessment coefficient as the heat pump operates, intuitively reflecting the gradual development process of frost severity. It avoids the problem of not being able to judge the frost trend by looking at single-cycle values ​​alone, and provides a continuous, systematic, and time-correlated data analysis foundation for the subsequent identification of frost deterioration periods. This upgrades the judgment of frost status from static numerical analysis to dynamic trend analysis.

[0045] In summary, comparing the coefficients of the current and previous monitoring cycles in the frost assessment change sequence, and defining the frost deterioration period by continuously increasing coefficients in consecutive cycles, can accurately identify the heat pump operation stage where the degree of frost is continuously aggravated. By comparing the values ​​of consecutive cycles, misjudgments caused by single-cycle coefficient fluctuations are avoided, ensuring that the definition of the frost deterioration period conforms to the actual development pattern of the frost degree. The key time range for defrosting intervention is clarified, so that the timing of subsequent defrosting is no longer blind, but focuses on the operation stage where frost has had a continuous negative impact, thus improving the targeting of defrosting control.

[0046] In summary, by obtaining the rate and direction of change of the return water temperature based on the initial and final values ​​of the heating operation data during the frosting deterioration period, the impact of frosting on the heat pump's heating effect can be transformed into the dynamic change characteristics of the return water temperature. As the core output indicator of heat pump heating, the rate and direction of change of the return water temperature directly reflect whether frosting has affected the heat pump's heating capacity. This method transforms the negative impact of frosting from an abstract coefficient change into a specific change in heating effect, providing a judgment basis that fits the actual heating efficiency of the heat pump for the precise positioning of the defrosting start-up time, and realizing the correlation analysis between the degree of frosting and the heating effect.

[0047] In summary, identifying the turning point in the monitoring cycle where the rate of change in return water temperature shifts from positive to negative during the frosting worsening period allows for precise capture of the critical moment when the impact of frosting transforms from quantitative to qualitative, and the heat pump's heating capacity begins to show a negative change. This turning point is the core indicator of the substantial negative impact of frosting on heating performance, preventing the waste of heating energy caused by starting defrosting too early, and also preventing a significant drop in heat pump heating efficiency caused by starting defrosting too late. This provides a precise numerical and trend-based standard for determining the timing of defrosting, improving the rationality of choosing the right time to start defrosting.

[0048] In summary, using the edge of the inflection point as a trigger signal to generate a defrost start identifier allows for precise linkage between the defrost start operation and key nodes in the development of heat pump frost. The generation of the trigger signal is based on the dual quantitative analysis results of the degree of frost and heating effect, rather than empirical subjective judgment, providing a clear and objective basis for the triggering of defrost start and ensuring that the defrost operation starts at the most appropriate time. At the same time, this identifier provides clear start instructions for subsequent defrost-related valve modulation and compressor frequency adjustment, forming an orderly linkage system for the entire defrost control process and improving the automation and precision of CO2 heat pump defrost control.

[0049] In an embodiment of the present invention, when configuring the opening degree of key valves and the frequency of the compressor in the target process sequentially based on the state parameters of the defrost start identifier to obtain the valve modulation sequence and compressor modulation sequence of the target process, it is specifically used for: Based on the defrosting start identifier, the current opening degree of the key valve in the target process is used as the benchmark, and the time difference sign of the frosting influence evaluation coefficient in the target process is used as the step direction of the target process; The opening of the current key valve is adjusted in unit steps according to the step direction, and the change response of the heat exchanger outlet temperature in the target process is detected: if the direction of the change response is consistent with the step direction, the current step direction of the target process will be retained; if the direction of the change response is inconsistent with the step direction, the current step direction of the target process will be reversed. Based on the direction of the change response, the opening change direction of the heat exchanger outlet temperature in an upward trend is iteratively screened, and the cumulative adjustment in the opening change direction is taken as the defrosting opening target value of the target process. The intermediate opening sequence required to reach the target defrost opening value is used as the valve modulation sequence for the target process; The compressor modulation sequence of the target process is determined based on the current exhaust pressure and intake pressure of the target process; The valve modulation sequence and the compressor modulation sequence are concatenated in chronological order to obtain the valve modulation sequence and compressor modulation sequence of the target process.

[0050] Specifically, after the system detects that the defrosting start flag has been triggered, it directly extracts the actual opening degree of the key valve at this moment in the target process and uses this opening degree value as the benchmark value for all subsequent opening degree adjustment operations. At the same time, it performs a time dimension change analysis on the frost impact assessment coefficient in the target process and determines the difference sign of the frost impact assessment coefficient in the time process. This sign intuitively reflects the time change trend of the frost impact assessment coefficient.

[0051] Specifically, using the determined step direction as the adjustment guide, a single unit step adjustment operation is performed on the current opening of the key valve in the target process. After the adjustment is completed, the heat exchanger outlet temperature in the target process is continuously monitored to accurately capture the numerical change of the heat exchanger outlet temperature after the valve opening is adjusted. This numerical change is the response of the heat exchanger outlet temperature change.

[0052] Specifically, after completing each unit step adjustment of the valve opening and determining whether to retain or reverse the step direction, the response direction of the heat exchanger outlet temperature change corresponding to each adjustment is continuously recorded. Taking the upward trend of the heat exchanger outlet temperature as the core screening criterion, the opening change direction in all adjustment processes is iteratively screened, eliminating the opening change direction that will cause the heat exchanger outlet temperature to decrease or remain unchanged, and only retaining the opening change direction that allows the heat exchanger outlet temperature to be in an upward trend.

[0053] Specifically, with the determined defrosting opening target value as the final adjustment endpoint and the initial reference opening of the key valve as the adjustment starting point, the specific opening value of the key valve after each unit step adjustment is identified during the process of gradually adjusting from the initial reference opening to the defrosting opening target value.

[0054] Specifically, while generating the valve modulation sequence, the specific values ​​of the compressor's discharge pressure and suction pressure at this moment in the target process are extracted in real time. These two sets of pressure values ​​are comprehensively analyzed. Combined with the adjustment requirements of the compressor's operating frequency during the defrosting process, and based on the actual numerical characteristics of the discharge pressure and suction pressure, the specific change process of the compressor frequency gradually adjusting from the current value is planned.

[0055] Specifically, the generated valve modulation sequence and compressor modulation sequence are used as two independent basic sequences. The time progression of the defrosting process is used as the core integration basis, and each opening adjustment node in the valve modulation sequence is integrated with each frequency adjustment node in the compressor modulation sequence.

[0056] Furthermore, the time difference sign obtained from the frost impact assessment coefficient is directly set as the step direction for adjusting the opening of key valves in the target process. Subsequent valve opening adjustment actions are all based on this step direction as the initial guiding direction, ensuring that the adjustment direction of the valve opening is accurately correlated with the time change characteristics of the frost impact assessment coefficient.

[0057] Furthermore, the direction of the change response is then compared with the initially set step direction. If the direction of the detected change response of the heat exchanger outlet temperature is consistent with the step direction, the current step direction is directly retained as the direction of subsequent adjustment. If the direction of the detected change response of the heat exchanger outlet temperature is opposite to the step direction, the current step direction is reversed to determine the new valve opening adjustment step direction.

[0058] Furthermore, in the selected effective opening change direction, the total adjustment amount of all unit step adjustments is accumulated and statistically analyzed. This accumulated adjustment amount is directly set as the defrosting opening target value of the key valve in the target process. This target value is the final value of the valve opening adjustment.

[0059] Furthermore, these intermediate opening values ​​arranged in chronological order of adjustment time are integrated into an ordered sequence. This sequence fully presents the gradual change of valve opening from the start point to the end point. This time-ordered intermediate opening sequence is the valve modulation sequence of the target process. Each value in the sequence corresponds to a specific adjustment time node and valve opening state.

[0060] Furthermore, the frequency values ​​and adjustment time points of each adjustment stage are clearly defined, and these compressor frequency adjustment information arranged in chronological order are integrated into an ordered sequence. This sequence is the compressor modulation sequence of the target process, ensuring that the frequency adjustment actions in the sequence are adapted to the pressure changes in the defrosting process.

[0061] Furthermore, the two sequences are precisely connected in series according to their actual execution time during the defrosting process, and then integrated into a comprehensive sequence that synchronously reflects the valve opening degree and compressor frequency adjustment. This comprehensive sequence formed after series connection is the final valve modulation sequence and compressor modulation sequence of the target process, ensuring that the adjustment actions of the valve and compressor during the defrosting process can be executed synchronously and orderly according to this sequence.

[0062] In summary, by using the defrosting start indicator as a trigger, taking the current critical valve opening as a benchmark, and using the time difference sign of the frosting impact assessment coefficient as the step direction, the initial adjustment direction of the valve opening can be precisely linked to the dynamic change trend of the frosting impact. This ensures that the adjustment action is aligned with the actual development state of the current frosting from the start stage. At the same time, using the actual operating valve opening as the adjustment benchmark avoids the adjustment deviation caused by a fixed benchmark, providing an initial basis for subsequent valve opening adjustments to align with the real-time operating state of the system, thus laying the foundation for precise valve opening modulation.

[0063] In summary, by using the step direction to drive the opening of key valve components in unit step adjustments, and adjusting the step direction in response to changes in the heat exchanger outlet temperature, precise control of valve opening can be achieved through small-amplitude unit step adjustments. This avoids system operation fluctuations caused by large adjustments. At the same time, using the actual change in the heat exchanger outlet temperature as the basis for adjusting the step direction forms a closed-loop control between the adjustment action and system operation feedback. This ensures that every opening adjustment moves in a direction conducive to defrosting, effectively avoiding the problem of reduced defrosting efficiency caused by blind adjustments, and improving the rationality and adaptability of valve opening adjustment.

[0064] In summary, by iteratively screening the opening direction with an upward trend in temperature response to heat exchanger outlet temperature changes, and setting the cumulative adjustment in this direction as the defrosting opening target value, the effective adjustment direction that can improve the heat exchanger outlet temperature can be accurately identified through iterative screening. This ensures that the heat exchange efficiency of the heat exchanger continues to improve during the defrosting process. At the same time, using the cumulative adjustment as the defrosting opening target value gives the valve opening adjustment a clear final direction, avoiding energy waste and system instability caused by aimless adjustment, and defining a clear target boundary for the valve opening adjustment during the defrosting stage.

[0065] In summary, using the intermediate opening sequence required to reach the defrost opening target value as the valve modulation sequence allows the opening adjustment of key valves to form an orderly step-by-step adjustment process from the initial reference to the target value. The clearly defined intermediate opening nodes in the sequence enable the valve opening to be adjusted smoothly and gradually, avoiding sudden changes in refrigerant flow in the heat pump system caused by adjusting to the target value all at once, thus ensuring the stability of system operation during defrosting. At the same time, this sequence provides a clear and executable operational basis for the actions of valve actuators, improving the standardization of valve adjustment.

[0066] In summary, determining the compressor modulation sequence based on the current discharge and suction pressures of the target process allows for precise matching of compressor frequency adjustment with the actual pressure state of the heat pump system. By combining the real-time changes in system pressure during defrosting to plan the frequency adjustment process, the problem of poor defrosting effect or excessive compressor operating load caused by mismatch between fixed frequency adjustment and system pressure is avoided. This ensures that the compressor frequency change can be coordinated with valve opening adjustment to optimize the refrigerant circulation state of the system, providing suitable compressor operating parameters to support efficient defrosting.

[0067] In summary, connecting the valve modulation sequence and the compressor modulation sequence in chronological order to form the final modulation sequence enables precise synchronization and coordinated execution of valve opening adjustment and compressor frequency adjustment in the time dimension. This avoids the system operating parameter disorder caused by the asynchronous adjustment of the two, ensuring that the actions of the valve and compressor cooperate and form a combined force during the defrosting process. This keeps the operating parameters of the heat pump system in the optimal state for defrosting. At the same time, the connected sequence provides a unified and complete action guide for the operation of the actuators during the defrosting stage, improving the coordination and automation level of the entire defrosting control process.

[0068] In an embodiment of the present invention, determining the compressor modulation sequence of the target process based on the current exhaust pressure and intake pressure of the target process is specifically used for: The process of reducing the compressor frequency is decomposed into various frequency pulse actions of the target process, which include a frequency descent step and a frequency holding step. The amplitude of the frequency descent step is determined by the sign of the pressure deviation between the exhaust pressure and the saturation pressure value corresponding to the current ambient temperature during the target process: if the sign of the pressure deviation is positive, the amplitude of the frequency descent step is set to a unit basic step size; if the sign of the pressure deviation is negative, the amplitude of the frequency descent step is set to zero. The duration of the frequency holding step is determined based on the fluctuation range of the compressor suction pressure during the target process: when the suction pressure fluctuation range at the end of the frequency holding step is less than the fluctuation range at the end of the preceding holding step in the target process, the current holding step of the target process ends; when the suction pressure fluctuation range at the end of the frequency holding step is greater than the fluctuation range at the end of the preceding holding step, the duration of the current holding step of the target process is set to a basic time unit. During the continuous sampling period of the target process, if the fluctuation amplitude at the end of the frequency holding step is smaller than the fluctuation amplitude of the preceding holding step, and the fluctuation amplitude is smaller than the absolute value of the heat exchanger outlet temperature change rate in the target process, the current compressor frequency of the target process is taken as the defrosting frequency target value of the target process. The various frequency pulse actions are connected in chronological order to form a compressor modulation sequence for the target process.

[0069] Specifically, the entire process in which the compressor frequency needs to be gradually reduced in the target process is broken down. The continuous frequency adjustment method is abandoned and it is broken down into multiple independent frequency adjustment actions that are executed sequentially in time. These independent adjustment actions are the diverse frequency pulse actions of the target process, and each diverse frequency pulse action consists of two core stages.

[0070] Specifically, the real-time exhaust pressure value of the compressor in the target process is first extracted, and then the saturation pressure value matching the current ambient temperature of the target process is obtained. The two sets of values ​​are compared and analyzed to obtain the pressure deviation between them. The specific sign of the pressure deviation is determined, and this sign is used as the sole criterion to determine the adjustment amplitude of the frequency drop step in the multi-frequency pulse action.

[0071] Specifically, during the frequency holding step phase of the multi-frequency pulse action, the numerical change of the compressor intake pressure during the target process is continuously monitored, and the intake pressure fluctuation amplitude at the end of the current frequency holding step is accurately calculated. At the same time, the intake pressure fluctuation amplitude recorded at the end of the previous frequency holding step is retrieved, and the two sets of fluctuation amplitudes are compared. Based on the comparison result, it is determined whether the duration of the current frequency holding step should continue.

[0072] Specifically, during the frequency adjustment phase of the target process, the continuous sampling cycle is tracked and monitored cycle by cycle. After each sampling cycle, the fluctuation amplitude of the compressor intake pressure at the end of the current frequency holding step is recorded and compared with the fluctuation amplitude of the previous holding step.

[0073] Specifically, all the various frequency pulse actions that are set and executed during the target process are sorted out, and these independent pulse actions are connected in sequence according to the actual execution time of each various frequency pulse action during the defrosting process to form a continuous and orderly frequency adjustment sequence.

[0074] Furthermore, these are the frequency reduction step and the frequency holding step. The frequency reduction step is the single-time reduction stage of the compressor frequency, and the frequency holding step is the stage of maintaining stable operation of the frequency after the single frequency reduction is completed. All the various frequency pulse actions are executed in sequence to jointly complete the process of reducing the compressor frequency from the initial value to the target value, ensuring that the frequency reduction process is precisely controlled through pulse-type step-by-step adjustment.

[0075] Furthermore, if the sign of the pressure deviation is positive, it means that the current exhaust pressure is higher than the saturation pressure value of the corresponding ambient temperature. The amplitude of this frequency descent step is directly set to the unit basic step size, and a single unit basic step size frequency reduction is performed. If the sign of the pressure deviation is negative, it means that the current exhaust pressure is lower than the saturation pressure value of the corresponding ambient temperature. The amplitude of this frequency descent step is directly set to zero. No frequency reduction operation is performed in this frequency descent step, and it only enters the subsequent frequency holding step.

[0076] Furthermore, if the fluctuation amplitude of the inhalation pressure at the end of the current hold step is less than the fluctuation amplitude at the end of the previous hold step, it indicates that the inhalation pressure is stabilizing. The current frequency hold step of the target process is then terminated directly, and the next multi-frequency pulse action begins. If the fluctuation amplitude of the inhalation pressure at the end of the current hold step is greater than the fluctuation amplitude at the end of the previous hold step, it indicates that the inhalation pressure is still unstable. The duration of the current hold step of the target process is increased by one basic time unit, and the current compressor frequency is maintained while the inhalation pressure fluctuation is continuously monitored.

[0077] Furthermore, when the comparison results in multiple consecutive sampling periods are all that the fluctuation amplitude of the current holding step is less than that of the previous holding step, and the fluctuation amplitude of the suction pressure in this stage is less than the absolute value of the rate of change of the heat exchanger outlet temperature in the target process, it indicates that the compressor's operating state has adapted to the needs of the defrosting process. The compressor frequency does not need to be adjusted downwards. The actual operating frequency of the compressor at this moment in the target process is directly determined as the defrosting frequency target value of the target process. This value is the final frequency value that the compressor needs to maintain stably during the defrosting process.

[0078] Furthermore, the connection process strictly follows the time principle of executing the pulse action first and the pulse action executed later, and fully retains the adjustment amplitude of the frequency drop step and the duration of the frequency holding step in each multi-frequency pulse action, ensuring that the sequence can accurately reflect the entire pulse-like adjustment process of the compressor frequency from the initial value to the defrosting frequency target value. This sequence connected in time order is the compressor modulation sequence of the target process.

[0079] In summary, the compressor frequency reduction process is decomposed into various frequency pulse actions, including frequency reduction steps and frequency holding steps. This eliminates the continuous frequency reduction method and breaks down the overall frequency reduction process into step-by-step pulse regulation. This avoids sudden changes in compressor operating load caused by a single large frequency reduction. At the same time, the setting of the frequency holding step allows the system sufficient time to adapt to the new frequency state after each frequency reduction, making the compressor frequency regulation more stable. This adapts to the gradual changes in system pressure and temperature during CO2 heat pump defrosting and ensures the operational stability of the compressor and the entire heat pump system during the defrosting frequency regulation phase.

[0080] In summary, the sign of the pressure deviation between the exhaust pressure and the saturation pressure corresponding to the current ambient temperature determines the magnitude of the frequency reduction step. This allows the compressor frequency reduction to be determined entirely based on the actual system pressure state. When the pressure deviation is positive, the frequency is reduced by a basic unit step, which can accurately alleviate the problem of high exhaust pressure and create suitable system pressure conditions for defrosting. When the pressure deviation is negative, the frequency reduction magnitude is set to zero, which can avoid unnecessary frequency reduction operations that could lead to reduced defrosting efficiency or excessive loss of heating capacity. This achieves precise and on-demand adjustment of the frequency reduction step magnitude, making the frequency adjustment highly compatible with the system pressure state.

[0081] In summary, the duration of the frequency holding step is determined by the fluctuation range of the compressor's suction pressure. The change in the suction pressure fluctuation range serves as the sole basis for adjusting the holding step duration. When the fluctuation range decreases, the holding step ends; when the fluctuation range increases, the holding step duration is extended. This allows the system sufficient time to stabilize the pressure after frequency adjustment, ensuring that the suction pressure tends to be stable after each frequency reduction before subsequent adjustments can be made. This avoids system operating parameter disturbances caused by continuing to reduce the frequency before the pressure is stable, effectively suppressing abnormal fluctuations in suction pressure and ensuring the pressure stability of the compressor's suction side during defrosting.

[0082] In summary, within a continuous sampling period, the current compressor frequency is set as the defrosting frequency target value based on the criterion that the fluctuation amplitude at the end of the frequency holding step is consistently less than that of the previous step and less than the absolute value of the heat exchanger outlet temperature change rate. This criterion combines the dual system operation indicators of suction pressure stability and heat exchanger temperature change characteristics, accurately locking in the optimal compressor frequency for the defrosting process. This ensures that the compressor frequency meets the pressure regulation requirements of defrosting and matches the temperature change state of the heat exchanger, avoiding abnormal system pressure caused by excessively high frequency and preventing excessively low frequency from affecting defrosting efficiency. This provides a scientific and quantitative basis for determining the defrosting frequency target value.

[0083] In summary, connecting diverse frequency pulse actions into a compressor modulation sequence in chronological order integrates scattered pulse-type frequency adjustment actions into an orderly and complete adjustment process. The sequence clearly presents the amplitude of each frequency descent step and the duration of each frequency hold step, providing clear and time-sequential operational guidance for the compressor's frequency adjustment actuators. This standardizes and normalizes the process of adjusting the compressor frequency from its initial value to the defrosting frequency target value. At the same time, this sequence can achieve precise time-dimensional coordination with the valve modulation sequence, ensuring synchronous linkage between the compressor and key valve adjustment actions during defrosting, and improving the coordinated operation capability of the entire defrosting control system.

[0084] In an embodiment of the present invention, the step of driving the actuator of the target process according to the valve modulation sequence and the compressor modulation sequence, and switching the defrosting mode of the target process when the exhaust pressure of the actuator reaches the transition equilibrium point of the target process, is specifically used for: According to the opening modulation step size in the valve modulation sequence and the frequency modulation step size in the compressor modulation sequence, the execution component of the target process is adjusted step by step to obtain the dynamic modulation sequence of the target process; Based on the dynamic modulation sequence, monitor the compressor discharge pressure and the corresponding pressure-time change curve of the target process; Calculate the fluctuation attenuation coefficient of exhaust pressure in adjacent monitoring cycles during the target process based on the pressure-time change curve. When the fluctuation attenuation coefficient shows a monotonically decreasing trend during the continuous monitoring period of the target process, the exhaust pressure of the target process is calibrated as the transition equilibrium exhaust pressure of the target process. When the compressor discharge pressure reaches the transition equilibrium discharge pressure, the refrigerant flow direction of the target process is switched to obtain the defrosting mode of the target process.

[0085] Specifically, a preset opening modulation step size is extracted from the generated valve modulation sequence, and a preset frequency modulation step size is extracted from the compressor modulation sequence. Using these two step sizes as fixed adjustment standards, step-by-step adjustment operations are carried out on all actuators such as valves and compressors in the target process.

[0086] Specifically, the generated dynamic modulation sequence is used as the monitoring basis. According to the time nodes and adjustment stages in the sequence, the compressor exhaust pressure in the target process is continuously and uninterruptedly monitored. The specific value of the compressor exhaust pressure is accurately collected in each monitoring cycle, and the precise collection time corresponding to each value is recorded.

[0087] Specifically, using the completed pressure-time variation curve as the core data carrier, the compressor exhaust pressure values ​​corresponding to two adjacent monitoring cycles in the target process are extracted from the curve. At the same time, the time interval between the two monitoring cycles is confirmed. Based on the exhaust pressure fluctuation state presented by the curve, combined with the pressure value changes and time intervals of adjacent monitoring cycles, the degree of exhaust pressure fluctuation is quantitatively calculated.

[0088] Specifically, the exhaust pressure fluctuation attenuation coefficient calculated for each monitoring cycle during the target process is recorded cycle by cycle. The changing trend of the fluctuation attenuation coefficient is sorted out according to the chronological order of monitoring time, and the numerical change of the fluctuation attenuation coefficient within multiple consecutive monitoring cycles is continuously checked.

[0089] Specifically, during continuous monitoring of the discharge pressure of the target process compressor, when the actual discharge pressure value is detected to reach the calibrated transition equilibrium discharge pressure value, the refrigerant flow direction switching operation is immediately triggered.

[0090] Furthermore, the adjustment process strictly follows the time nodes and adjustment ranges in the sequence. First, the valve opening is adjusted once according to the opening modulation step size, and then the corresponding compressor frequency is adjusted according to the frequency modulation step size. All adjustment actions corresponding to the step size are completed in sequence. At the same time, the actual operating status of the actuator, the adjustment time, and the corresponding opening and frequency values ​​are recorded after each adjustment. These contents containing adjustment information and status information are integrated into an ordered sequence according to the actual adjustment time sequence. This sequence, which can reflect the adjustment process of the actuator in real time, is the dynamic modulation sequence of the target process.

[0091] Furthermore, all the collected exhaust pressure values ​​are used as the vertical axis data and the corresponding collection time is used as the horizontal axis data. The two are matched one by one and plotted to form a continuous curve. This curve can intuitively show the numerical change of the compressor exhaust pressure over time. This complete curve is the pressure-time change curve of the target process. The trend of the curve directly reflects the dynamic change characteristics of the exhaust pressure during the adjustment process.

[0092] Furthermore, the calculation process fully considers key characteristics such as the pressure fluctuation amplitude and fluctuation speed from the previous monitoring cycle to the current monitoring cycle. Through quantitative analysis, a specific value that reflects the degree of reduction in exhaust pressure fluctuation between adjacent monitoring cycles is obtained. This value is the exhaust pressure fluctuation attenuation coefficient between adjacent monitoring cycles in the target process. The magnitude of the coefficient directly reflects the attenuation of exhaust pressure fluctuation.

[0093] Furthermore, when it is found that the fluctuation attenuation coefficient shows a monotonically decreasing trend in successive monitoring cycles, it indicates that the fluctuation of the compressor discharge pressure is continuously weakening and the overall state is stabilizing. At this time, the actual discharge pressure value of the compressor in this stage is directly calibrated. This calibrated discharge pressure value is the transition equilibrium discharge pressure of the target process. This pressure is the key value node for the discharge pressure to reach stability during the defrosting process.

[0094] Furthermore, by controlling the on / off state of key valves such as reversing valves in the target process, the flow path of refrigerant in the heat pump system pipeline is changed, allowing the refrigerant that originally flowed to the heating heat exchange pipeline to flow to the outdoor heat exchanger pipeline where it is frosted. The condensation heat of the refrigerant is used to defrost the frosted heat exchanger. After completing all the refrigerant flow direction switching operations, the heat pump system enters a dedicated defrosting operation state. This operation state after completing the refrigerant flow direction switching is the defrosting mode of the target process.

[0095] In summary, by adjusting the actuator step by step according to the valve opening modulation step and the compressor frequency modulation step, a dynamic modulation sequence is obtained. This allows the adjustment of valve opening and compressor frequency to strictly follow the preset step size and proceed in an orderly manner, achieving precision and standardization of actuator adjustment. This avoids system operating parameter disorder caused by irregular adjustment. At the same time, the dynamic modulation sequence completely records all operating parameters and time nodes in the step-by-step adjustment process, transforming the static modulation sequence into a dynamic adjustment trajectory that fits the actual operation of the system. This provides a precise and synchronous adjustment background for subsequent exhaust pressure monitoring and analysis, ensuring a high degree of matching between pressure monitoring and actuator adjustment.

[0096] In summary, monitoring compressor exhaust pressure based on dynamic modulation sequence and plotting pressure-time variation curves allows for complete synchronization between the exhaust pressure monitoring process and the dynamic adjustment process of the actuators. This accurately captures the real-time changes in exhaust pressure after each adjustment action. The pressure-time variation curves visually present the fluctuation trend of exhaust pressure as the adjustment process progresses, transforming discrete pressure monitoring values ​​into continuous change trajectories. This clearly reflects the correlation between adjustment actions and pressure changes, providing a complete, continuous, and time-correlated pressure data foundation for the subsequent calculation of fluctuation attenuation coefficients, making pressure analysis more systematic.

[0097] In summary, calculating the exhaust pressure fluctuation attenuation coefficient between adjacent monitoring periods based on the pressure-time variation curve allows for a quantitative assessment of the degree of reduction in exhaust pressure fluctuations. This transforms the intuitive fluctuation trend in the pressure-time variation curve into specific quantitative values, eliminating the influence of subjective judgment on the identification of pressure stability. It accurately reflects the attenuation characteristics of exhaust pressure fluctuations within adjacent monitoring periods, upgrading the judgment of exhaust pressure stability from qualitative to quantitative analysis. This provides a scientific and quantitative core judgment indicator for the subsequent calibration of transitional equilibrium exhaust pressure, improving the accuracy and objectivity of pressure state judgment.

[0098] In summary, when the fluctuation attenuation coefficient shows a monotonically decreasing trend within the continuous monitoring period, the exhaust pressure is calibrated as the transitional equilibrium exhaust pressure. This can accurately identify the key node in the transition of exhaust pressure from continuous fluctuation to a stable state. The monotonically decreasing fluctuation attenuation coefficient directly reflects that the fluctuation amplitude of exhaust pressure is continuously decreasing and tending to be stable. Using this as a calibration basis can effectively avoid misjudgment caused by a single pressure fluctuation, ensuring that the calibrated transitional equilibrium exhaust pressure is the stable pressure value reached after system adjustment. This provides a precise and objective pressure judgment standard for switching defrosting modes, giving quantitative basis to the timing of mode switching.

[0099] In summary, switching the refrigerant flow direction and entering defrost mode when the compressor discharge pressure reaches the transition equilibrium discharge pressure allows the defrost mode switching to precisely match the stable state of the system pressure. This avoids problems such as refrigerant circulation disorder and sudden increase in system operating load caused by switching the flow direction when the pressure is unstable, ensuring the operational stability of the heat pump system during mode switching. At the same time, defrosting based on a stable pressure state allows the refrigerant to maintain a reasonable circulation state in defrost mode, fully utilizing the defrost heat exchange efficiency of the CO2 heat pump and improving the defrost effect. It also transforms the start-up of the defrost mode from passive triggering to active and precise switching based on the stable state of the system, significantly improving the scientific and precise level of defrost control.

[0100] In this embodiment of the invention, the formula for calculating the fluctuation attenuation coefficient is specifically used for: in, For the first The dimensionless fluctuation attenuation coefficient for each monitoring period For sampling period index, The exhaust pressure for the current monitoring period. The exhaust pressure from the previous monitoring period. The exhaust pressure is from the first two monitoring cycles. For the duration of the monitoring period, For the width of the history window, This is the position index within the historical fluctuation window.

[0101] Specifically, all parameters related to the dimensionless fluctuation attenuation coefficient are derived from real-time monitoring data of the compressor discharge pressure during the target process and preset monitoring rules. The sampling period index is a sequence number assigned to each monitoring period according to the order of discharge pressure monitoring. The discharge pressure of the current, previous, and two previous monitoring periods are actual values ​​obtained by accurately collecting the compressor discharge pressure within the corresponding monitoring period. The monitoring period duration is a fixed time interval set in advance before discharge pressure monitoring is carried out. The historical window width is a standard for the number of historical monitoring data to be extracted in advance according to the actual needs of defrosting control. The position index in the historical fluctuation window is a sequence number assigned to each monitoring period in the historical window according to the time sequence. All parameters directly serve the calculation of the dimensionless fluctuation attenuation coefficient, and the values ​​are all determined actual collected values ​​or preset values.

[0102] Furthermore, the core significance of this formula is to perform a dimensionless quantitative assessment of the degree of fluctuation attenuation of compressor exhaust pressure within adjacent monitoring cycles during the target process. By integrating the characteristics of exhaust pressure changes, monitoring time intervals, and historical exhaust pressure fluctuations from the current and previous two monitoring cycles, it eliminates the influence of different dimensions on pressure fluctuation analysis, accurately reflects the weakening trend and stability of exhaust pressure fluctuations within continuous monitoring cycles, and the calculated dimensionless fluctuation attenuation coefficient can intuitively reflect the change state of exhaust pressure from fluctuation to stability. It provides an accurate and quantitative basis for judging whether the compressor exhaust pressure has reached a transitional equilibrium state, and is the core calculation basis for assessing the exhaust pressure state during the defrosting mode switching process.

[0103] In summary, the numerical trend of this formula is directly related to the fluctuation of the compressor exhaust pressure. When the fluctuation amplitude of the compressor exhaust pressure gradually decreases and the pressure state tends to stabilize during the target process, the dimensionless fluctuation attenuation coefficient calculated by the formula will show a monotonically decreasing trend. Specifically, the coefficient value of the later monitoring cycle is always less than the coefficient value of the previous monitoring cycle. When the exhaust pressure fluctuation amplitude is larger and the pressure state is more unstable, the value of the dimensionless fluctuation attenuation coefficient will remain at a high level and there will be no obvious decreasing trend. When the exhaust pressure is completely stable and there is no obvious fluctuation, the value of the dimensionless fluctuation attenuation coefficient will gradually approach zero. The trend change of this formula can accurately map the entire process of exhaust pressure from fluctuation to stability and is a direct numerical basis for judging the transitional equilibrium state of exhaust pressure.

[0104] In this invention embodiment, when determining the defrosting progress index of the target process based on the defrosting mode and according to the temporal relationship between the time of the extreme point of the heat exchanger outlet temperature in the target process and the time when the compressor suction pressure falls to the saturation pressure value corresponding to the current ambient temperature in the target process, it is specifically used for: Based on the defrosting mode, record the peak operating temperature of the heat exchanger outlet and the corresponding peak time during the target process; The moment when the compressor suction pressure changes from decreasing to increasing during the target process is taken as the pressure recovery moment of the target process. When the peak time is earlier than the pressure recovery time, the initial defrosting phase indicator of the target process is obtained; When the peak moment and the pressure recovery moment are both recorded in the target process record, the defrosting end point identifier of the target process is obtained; The initial defrosting indicator and the final defrosting indicator are combined to form the defrosting progress index of the target process.

[0105] Specifically, after the target process enters the defrosting mode, continuous monitoring of the heat exchanger outlet temperature is initiated. The specific value of the heat exchanger outlet temperature is collected sequentially according to the set monitoring cycle, and the collection time corresponding to each temperature value is accurately recorded. All collected temperature values ​​are associated with their corresponding times and archived. During the monitoring process, the temperature values ​​of each cycle are continuously compared, and the heat exchanger outlet temperature value with the largest value is selected. This value is the operating peak value of the heat exchanger outlet temperature in the target process.

[0106] Specifically, during the entire process when the target process is in defrosting mode, the compressor suction pressure is continuously and dynamically monitored. Real-time values ​​of the compressor suction pressure are collected at fixed time intervals, and the specific time of each collection is recorded synchronously. The suction pressure values ​​at each time point are then arranged into a pressure change trajectory in chronological order.

[0107] Specifically, from the monitoring data archive of the target process defrosting mode, the peak time of the recorded heat exchanger outlet temperature and the pressure recovery time of the calibrated compressor suction pressure are retrieved, and the time sequence of the two times is accurately compared.

[0108] Specifically, in the defrosting mode monitoring of the target process, the recorded information in the monitoring data archive is continuously checked. When the peak moment of the heat exchanger outlet temperature and the pressure rise moment of the calibrated compressor suction pressure are found in the records of the same monitoring period, and both moments are effectively archived without any missing data, a special signal for identifying the defrosting process is directly generated.

[0109] Specifically, the generated initial defrosting identifier and final defrosting identifier are extracted from the monitoring identifier storage archive of the target process defrosting mode. The two identifiers are used as the core elements for determining the defrosting process, and the two identifiers are integrated and processed according to the time sequence of the defrosting process.

[0110] Furthermore, the acquisition time corresponding to the peak value is retrieved, and this time is determined as the peak value of the heat exchanger outlet temperature in the target process. This completes the recording of the peak value and peak value time and saves them in the monitoring data archive of the target process.

[0111] Furthermore, the trajectory was analyzed segment by segment to identify the key node in which the compressor suction pressure value changed from a continuously decreasing state to a continuously increasing state. This node is the inflection point of the suction pressure change. The specific acquisition time corresponding to this inflection point was then extracted and directly determined as the pressure recovery time of the target process. After the pressure recovery time was calibrated, it was synchronously recorded into the special monitoring data of the defrosting mode.

[0112] Furthermore, using the timeline as the sole criterion, when it is clearly found that the peak moment is earlier than the pressure rise moment, a unique signal is directly generated to identify the defrosting process. This signal clearly reflects that the target process is in the initial stage of defrosting. This unique signal is the initial defrosting identifier of the target process. After generation, this identifier is associated with and stored in relation to the corresponding time comparison results.

[0113] Furthermore, this signal can clearly reflect that the target process is in the final stage of defrosting. This exclusive signal is the defrosting end marker of the target process. After it is generated, the marker is associated with the corresponding dual-time record information and stored to ensure that the marker accurately matches the actual state of the defrosting process.

[0114] Furthermore, key related information such as the generation time and judgment criteria corresponding to each identifier is retained, and this information is bound to the identifier itself to form a comprehensive identifier set that can fully reflect the complete process of defrosting from the beginning to the end of the target process. This set can accurately reflect the time nodes and process status of each stage of defrosting. This comprehensive identifier set is the defrosting progress indicator of the target process. After the indicator is generated, it is retained as the core basis for the control of the defrosting process.

[0115] In summary, recording the peak operating temperature and corresponding peak time of the heat exchanger outlet temperature in defrost mode can accurately capture key characteristic points of heat exchanger temperature changes during defrost. The heat exchanger outlet temperature directly reflects the defrost heat exchange effect of the heat exchanger, and its peak operating temperature is an important node of temperature change during the defrost stage. Accurate recording of this peak and its corresponding time can transform the dynamic temperature of the heat exchanger during the defrost process into specific numerical values ​​and time markers, providing an intuitive and specific temperature dimension basis for subsequent stage judgment of the defrost process. At the same time, it can also clearly reflect the temperature increase effect of the heat exchanger in the early stage of defrost, giving the judgment of the defrost effect a clear temperature reference standard.

[0116] In summary, defining the moment when the compressor suction pressure changes from decreasing to increasing as the pressure recovery moment allows for precise capture of the core node in system pressure changes during defrosting. The change in compressor suction pressure is directly related to the degree of frost melting on the heat exchanger. Gradual frost melting improves the heat exchanger's efficiency, leading to a change in suction pressure from decreasing to increasing. This pressure recovery moment is a key indicator of a qualitative change in system pressure during the defrosting process. Clearly defining it transforms the abstract defrosting process into a specific pressure time node, providing a pressure dimension that aligns with the actual operation of the system for determining the defrosting stage, and achieving a precise correlation between the defrosting process and system pressure changes.

[0117] In summary, generating an initial defrost indicator when the peak value precedes the pressure recovery time allows for precise determination of the initial stage of the defrost process based on the temporal relationship between the two core system indicators: temperature and pressure. This determination method combines the dual change characteristics of heat exchanger temperature and compressor pressure, avoiding misjudgments of the defrost stage caused by relying on a single indicator. The generation of the initial defrost indicator clearly defines the initial stage of defrost operation, allowing the system to clearly understand that defrosting is currently in the initial stage and the frost is beginning to melt. This provides clear stage guidance for subsequent targeted defrost parameter adjustments, ensuring that the parameter adjustments for the initial defrost stage are adapted to the system's operating status at that stage.

[0118] In summary, generating a defrosting end marker when both the peak time and the pressure recovery time appear simultaneously in the record allows for accurate determination of the final stage of the defrosting process based on the synchronous presentation of both temperature and pressure indicators. The simultaneous recording of these two times signifies that the heat exchanger temperature has reached its peak and the system pressure has recovered, indicating that the frost on the heat exchanger has essentially melted and the defrosting effect has met expectations. This determination method, based on the completion status of the core indicators of the defrosting process, can objectively and accurately identify the defrosting end stage. The generation of the defrosting end marker can convey a clear signal to the system that defrosting is about to be completed, avoiding the waste of heating energy and reduced system operating efficiency caused by excessive defrosting, and improving the economic efficiency of defrosting control.

[0119] In summary, combining the initial and final defrost indicators into a defrost progress index integrates the two key stages of the defrost process into a comprehensive basis for judging the defrost progress. This index incorporates the system's operational characteristics from both heat exchanger temperature and compressor pressure, comprehensively and accurately reflecting the complete defrost process from its initial to its final stage. This allows the system's judgment of defrost progress to move beyond a single stage or indicator, forming a systematic understanding of the process. Furthermore, the defrost progress index provides a clear and quantifiable basis for subsequent heating recovery operations, enabling precise matching of the timing and parameter adjustments for heating recovery with the actual defrost progress. This achieves seamless integration between defrost and heating recovery, improving the consistency and precision of the entire CO2 heat pump defrost control process.

[0120] In this embodiment of the invention, when adjusting the opening degree of key valves and compressor frequency of the target process according to the defrosting progress index to obtain the heating recovery command of the target process, it is specifically used for: The opening degree of the key valve corresponding to the initial defrosting indicator in the defrosting progress index is taken as the recovery target opening degree of the target process, and the corresponding compressor frequency is taken as the recovery target frequency of the target process. Based on the defrosting end-of-defrosting indicator in the defrosting progress index, the opening degree of the key valve and the compressor frequency are successively approximated to the recovery target opening degree and the recovery target frequency to obtain the test sequence of the target process; When the real-time deviation value in each consecutive period of the test sequence is not greater than the previous deviation value, the heating recovery command of the target process is obtained.

[0121] Specifically, the initial defrost indicator is accurately extracted from the defrost progress indicators of the target process. The actual opening value of the key valve in the target process when the initial defrost indicator is generated is retrieved. This opening value is directly set as the target opening value for the heating recovery stage of the target process. At the same time, the actual operating frequency value of the compressor when the initial defrost indicator is generated is retrieved. This frequency value is directly set as the target recovery frequency for the heating recovery stage of the target process.

[0122] Specifically, the defrosting end marker is extracted from the defrosting progress index of the target process. After the marker is triggered, the heating recovery adjustment operation of the key valve opening and compressor frequency is started. The set recovery target opening and recovery target frequency are used as the adjustment endpoint, and the actual valve opening and actual compressor frequency at the time the defrosting end marker is triggered are used as the adjustment starting point.

[0123] Specifically, during the test sequence execution phase of the target process, each adjustment cycle is monitored in real time. After each cycle, the real-time deviation between the current valve opening, compressor frequency and the corresponding recovery target value is calculated. At the same time, the real-time deviation value of the previous adjustment cycle is retrieved, and the real-time deviation values ​​of the current cycle and the previous cycle are compared.

[0124] Furthermore, the target opening degree and target frequency for restoration, as the final values ​​for adjusting key valves and compressors during the heating recovery process, will be fully recorded and used as the core reference standard for all subsequent adjustment operations, ensuring that the operating parameters of valves and compressors after heating recovery remain consistent with the adaptation parameters at the beginning of defrosting.

[0125] Furthermore, the valve opening and compressor frequency are adjusted synchronously and sequentially according to a fixed unit adjustment step. After each adjustment, the valve opening and compressor frequency are moved closer to the target opening and frequency by one unit step. At the same time, the time point of each adjustment, the adjusted valve opening value, the compressor frequency value, and the deviation between the value and the target value are recorded. All the adjustment information and deviation records arranged in the adjustment order are integrated into an ordered sequence. This sequence is the test sequence of the target process, which fully presents the sequential adjustment process of heating recovery.

[0126] Furthermore, the comparison results of multiple consecutive adjustment cycles are continuously tracked and recorded. When it is detected that the real-time deviation value of each cycle in the test sequence is not greater than the real-time deviation value of the previous cycle, it indicates that the opening degree of the key valve and the compressor frequency are continuously and stably approaching the recovery target value, and the adjustment process is in a stable convergence state. At this time, the heating recovery command of the target process is directly generated. This command is the core signal that triggers the heat pump system to officially enter the heating operation state. After receiving the command, the system will operate stably according to the recovery target opening degree and recovery target frequency.

[0127] In summary, by using the opening degree of key valves corresponding to the initial defrosting indicator in the defrosting progress index as the target opening degree and the corresponding compressor frequency as the target frequency, this method uses the valve and compressor parameters that are adapted to defrosting and operate stably in the initial defrosting stage as the benchmark for heating recovery. These parameters are the optimal parameters verified by actual operation in the initial defrosting stage and adapted to the operating conditions of the heat pump system. This avoids the mismatch problem caused by using fixed parameters as the recovery target, which is not in line with the actual operating conditions. It gives the parameter adjustment for heating recovery a clear final direction that fits the actual operating state of the system, ensuring that the system can quickly return to a stable and efficient heating operation state after heating recovery. This lays a scientific and adapted target foundation for subsequent successive approximation adjustments.

[0128] In summary, based on the defrost end marker in the defrost progress index, the opening degree of key valves and the compressor frequency are successively approximated towards the target opening degree and target frequency to obtain a test sequence. The triggering of the defrost end marker indicates that the defrost process is nearing completion. At this time, the successive approximation adjustment can avoid the problem of incomplete defrosting caused by premature adjustment. At the same time, the successive approximation adjustment method abandons the operation of adjusting to the target value all at once. It adjusts parameters step by step with small steps, which effectively prevents problems such as refrigerant circulation disorder, pressure and temperature fluctuations caused by parameter mutations in the heat pump system. The generated test sequence fully records the parameter changes and time nodes of each adjustment step, providing an orderly and executable operation guide for parameter adjustment for heating recovery, and ensuring the operational stability of the system during the adjustment process.

[0129] In summary, a heating recovery command is generated when the real-time deviation value in a continuous cycle within the test sequence is not greater than the previous deviation value. The real-time deviation value directly reflects the degree of deviation between the current valve opening, compressor frequency, and the recovery target value. If the deviation continues to decrease or remains unchanged within a continuous cycle, it indicates that the parameter adjustment is in a stable convergence state and the system has gradually adapted to the recovery target parameters. Using this as a judgment condition to generate a heating recovery command can accurately capture the key node when the system is most suitable for formally switching to heating operation. This avoids system instability caused by prematurely triggering heating recovery when the adjustment has not converged, and also prevents energy waste and heating start-up delay caused by over-adjustment. This provides a quantitative and objective judgment basis for the generation of heating recovery commands, ensuring a smooth and seamless switch of the heat pump system from defrosting mode to heating mode, achieving a seamless connection between defrosting and heating, and significantly improving the continuity of the entire heat pump system operation and the accuracy of heating recovery.

[0130] Compared with the prior art, the present invention has the following beneficial effects: 1. This technology achieves quantitative assessment of the impact of frosting and accurate identification of the frosting deterioration period through precise acquisition and analysis of CO2 heat pump heating operation data. It determines the defrosting initiation timing based on the trend characteristics of the return water temperature change rate, providing a scientific and quantitative basis for defrosting initiation and significantly improving the accuracy of defrosting initiation timing selection. Simultaneously, the technology designs a dynamic modulation sequence generation method for valve opening and compressor frequency, combining real-time feedback of system pressure and temperature for step size adjustment and parameter iterative optimization. This achieves refined and dynamic adaptability of the actuator adjustment during the defrosting process, ensuring the stability of system operating parameters during the defrosting phase, effectively improving the execution efficiency of defrosting operations, and ensuring that the defrosting process is always highly consistent with the actual operating state of the heat pump system.

[0131] 2. This technology divides the defrosting process into stages by monitoring changes in core operating indicators, forming a comprehensive index that fully reflects the defrosting progress. This provides clear stage guidance for switching defrosting modes and adjusting parameters, achieving refined control of the defrosting process. During the heating recovery stage, the stable operating parameters at the initial stage of defrosting are used as the recovery target. A test sequence is generated through successive approximation adjustments, and the timing of heating recovery is determined based on the convergence of parameter adjustments. This makes parameter adjustments for heating recovery more targeted, achieving a smooth transition from defrosting mode to heating mode. This effectively shortens the system's stabilization time for heating recovery, ensuring the continuity and efficiency of the heat pump system's heating operation. It comprehensively improves the overall precision and automation level of CO2 heat pump defrosting control, ensuring the heating performance of the heat pump system in low-temperature environments.

[0132] like Figure 2 The diagram shown is a functional block diagram of a CO2 heat pump defrosting control system based on model prediction provided in an embodiment of the present invention.

[0133] The model-based CO2 heat pump defrosting control system 100 described in this invention can be installed in an electronic device. Depending on the functions implemented, the model-based CO2 heat pump defrosting control system 100 may include a frosting assessment module 101, a defrosting start-up module 102, a modulation sequence module 103, a switching defrosting module 104, a progress indicator module 105, and a heating recovery module 106. The module described in this invention can also be called a unit, referring to a series of computer program segments that can be executed by the processor of an electronic device and perform a fixed function, stored in the memory of the electronic device.

[0134] In this embodiment, the functions of each module / unit are as follows: The frosting assessment module collects heating operation data of the target process and determines the frosting impact assessment coefficient of the target process based on the degree of deviation between the actual heat exchange temperature difference and the theoretical heat exchange temperature difference in the heating operation data. The defrosting start-up module identifies the defrosting deterioration period of the target process based on the changing trend of the defrosting impact assessment coefficient, and locates the turning point where the rate of change of return water temperature in the heating operation data changes from positive to negative within the defrosting deterioration period, thereby obtaining the defrosting start-up identifier of the target process. The modulation sequence module sequentially configures the opening degree of key valves and the frequency of the compressor in the target process based on the state parameters of the defrost start identifier, thereby obtaining the valve modulation sequence and compressor modulation sequence of the target process; The defrosting module is switched to drive the actuator of the target process according to the valve modulation sequence and the compressor modulation sequence, and the defrosting mode of the target process is switched when the exhaust pressure of the actuator reaches the transition equilibrium point of the target process. The progress indicator module, based on the defrosting mode, determines the defrosting progress indicator of the target process according to the temporal relationship between the time of the extreme point of the heat exchanger outlet temperature in the target process and the time when the compressor suction pressure falls to the saturation pressure value corresponding to the current ambient temperature in the target process. The heating recovery module adjusts the opening degree of key valves and compressor frequency of the target process according to the defrosting progress index to obtain the heating recovery command for the target process. In the several embodiments provided by this invention, it should be understood that the disclosed methods and systems can be implemented in other ways. For example, the system embodiments described above are merely illustrative; for example, the division of modules is only a logical functional division, and other division methods may be used in actual implementation.

[0135] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0136] Furthermore, the functional modules in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or in the form of hardware plus software functional modules.

[0137] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0138] The embodiments of this application can acquire and process relevant data based on artificial intelligence technology. Artificial intelligence is the theory, method, technology, and application system that uses digital computers or machines controlled by digital computers to simulate, extend, and expand human intelligence, perceive the environment, acquire knowledge, and use that knowledge to obtain optimal results.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A model-predictive CO2 heat pump defrosting control method, characterized in that, The method includes: Collect heating operation data of the target process, and determine the frosting impact assessment coefficient of the target process based on the degree of deviation between the actual heat exchange temperature difference and the theoretical heat exchange temperature difference of the heating operation data; Based on the changing trend of the frost impact assessment coefficient, the frost deterioration period of the target process is identified, and within the frost deterioration period, the turning point where the rate of change of return water temperature in the heating operation data changes from positive to negative is located, thereby obtaining the defrosting start indicator of the target process. Based on the status parameters of the defrost start indicator, the opening degree of key valves and the frequency of the compressor in the target process are configured sequentially to obtain the valve modulation sequence and compressor modulation sequence of the target process; The actuator of the target process is driven according to the valve modulation sequence and the compressor modulation sequence, and the defrosting mode of the target process is switched when the exhaust pressure of the actuator reaches the transition equilibrium point of the target process. Based on the defrosting mode, the defrosting progress index of the target process is determined according to the temporal relationship between the time of the extreme point of the heat exchanger outlet temperature in the target process and the time when the compressor suction pressure falls to the saturation pressure value corresponding to the current ambient temperature in the target process. Based on the defrosting progress index, the opening degree of key valves and the compressor frequency of the target process are adjusted to obtain the heating recovery command of the target process.

2. The CO2 heat pump defrosting control method based on model prediction as described in claim 1, characterized in that, The process involves collecting heating operation data for the target process and determining the frosting impact assessment coefficient for the target process based on the deviation between the actual heat exchange temperature difference and the theoretical heat exchange temperature difference from the heating operation data. This includes: The difference between the outdoor heat exchanger inlet temperature and the outdoor heat exchanger outlet temperature in the heating operation data is taken as the actual heat exchange temperature difference of the target process. The average difference between the outdoor heat exchanger inlet temperature and the outdoor heat exchanger outlet temperature in the heating operation data is taken as the theoretical heat exchange temperature difference of the target process. The difference between the actual heat exchange temperature difference and the theoretical heat exchange temperature difference is taken as the temperature difference deviation value of the target process; The ratio of the temperature difference deviation to the theoretical heat exchange temperature difference is used as the frost impact evaluation coefficient for the target process.

3. The CO2 heat pump defrosting control method based on model prediction as described in claim 1, characterized in that, The step of identifying the frosting deterioration period of the target process based on the changing trend of the frosting impact assessment coefficient, and locating the turning point where the rate of change of return water temperature in the heating operation data changes from positive to negative within the frosting deterioration period, to obtain the defrosting start indicator of the target process, includes: By monitoring the value of the frost impact assessment coefficient within the sampling period during the target process, the frost assessment change sequence of the target process is obtained; The frost impact assessment coefficient of the current monitoring period in the frost assessment change sequence is compared with the frost impact assessment coefficient of the previous monitoring period: when the comparison results of the continuous monitoring periods in the target process all indicate that the frost impact assessment coefficient of the current monitoring period is greater than the frost impact assessment coefficient of the previous monitoring period, the continuous monitoring period is defined as the frost deterioration period of the target process. The rate of change and the corresponding direction of the return water temperature are obtained based on the initial and final values ​​of the return water temperature in the heating operation data during the frosting deterioration period. When the rate of change of return water temperature in the current monitoring cycle is negative and the rate of change in the previous monitoring cycle is positive, the current monitoring cycle is positioned as the turning point of the target process. Using the edge of the inflection point as a trigger signal, the defrosting start indicator of the target process is obtained.

4. The CO2 heat pump defrosting control method based on model prediction as described in claim 1, characterized in that, The process of sequentially configuring the opening degree of key valves and the frequency of the compressor in the target process based on the state parameters of the defrost start identifier yields the valve modulation sequence and compressor modulation sequence of the target process, including: Based on the defrosting start identifier, the current opening degree of the key valve in the target process is used as the benchmark, and the time difference sign of the frosting influence evaluation coefficient in the target process is used as the step direction of the target process; The opening of the current key valve is adjusted in unit steps according to the step direction, and the change response of the heat exchanger outlet temperature in the target process is detected: if the direction of the change response is consistent with the step direction, the current step direction of the target process will be retained; if the direction of the change response is inconsistent with the step direction, the current step direction of the target process will be reversed. Based on the direction of the change response, the opening change direction of the heat exchanger outlet temperature in an upward trend is iteratively screened, and the cumulative adjustment in the opening change direction is taken as the defrosting opening target value of the target process. The intermediate opening sequence required to reach the target defrost opening value is used as the valve modulation sequence of the target process; The compressor modulation sequence of the target process is determined based on the current exhaust pressure and intake pressure of the target process; The valve modulation sequence and the compressor modulation sequence are concatenated in chronological order to obtain the valve modulation sequence and compressor modulation sequence of the target process.

5. The CO2 heat pump defrosting control method based on model prediction as described in claim 4, characterized in that, Determining the compressor modulation sequence of the target process based on the current exhaust pressure and intake pressure of the target process includes: The process of reducing the compressor frequency is decomposed into various frequency pulse actions of the target process, which include a frequency descent step and a frequency holding step. The amplitude of the frequency descent step is determined by the sign of the pressure deviation between the exhaust pressure and the saturation pressure value corresponding to the current ambient temperature during the target process: if the sign of the pressure deviation is positive, the amplitude of the frequency descent step is set to a unit basic step size; if the sign of the pressure deviation is negative, the amplitude of the frequency descent step is set to zero. The duration of the frequency holding step is determined based on the fluctuation range of the compressor suction pressure during the target process: when the suction pressure fluctuation range at the end of the frequency holding step is less than the fluctuation range at the end of the preceding holding step in the target process, the current holding step of the target process ends; when the suction pressure fluctuation range at the end of the frequency holding step is greater than the fluctuation range at the end of the preceding holding step, the duration of the current holding step of the target process is set to a basic time unit. During the continuous sampling period of the target process, if the fluctuation amplitude at the end of the frequency holding step is smaller than the fluctuation amplitude of the preceding holding step, and the fluctuation amplitude is smaller than the absolute value of the heat exchanger outlet temperature change rate in the target process, the current compressor frequency of the target process is taken as the defrosting frequency target value of the target process. The various frequency pulse actions are connected in chronological order to form a compressor modulation sequence for the target process.

6. The CO2 heat pump defrosting control method based on model prediction as described in claim 1, characterized in that, The step of driving the actuator of the target process according to the valve modulation sequence and the compressor modulation sequence, and switching the defrosting mode of the target process when the exhaust pressure of the actuator reaches the transition equilibrium point of the target process, includes: According to the opening modulation step size in the valve modulation sequence and the frequency modulation step size in the compressor modulation sequence, the execution component of the target process is adjusted step by step to obtain the dynamic modulation sequence of the target process; Based on the dynamic modulation sequence, monitor the compressor discharge pressure and the corresponding pressure-time change curve of the target process; Calculate the fluctuation attenuation coefficient of exhaust pressure in adjacent monitoring cycles during the target process based on the pressure-time change curve. When the fluctuation attenuation coefficient shows a monotonically decreasing trend during the continuous monitoring period of the target process, the exhaust pressure of the target process is calibrated as the transition equilibrium exhaust pressure of the target process. When the compressor discharge pressure reaches the transition equilibrium discharge pressure, the refrigerant flow direction of the target process is switched to obtain the defrosting mode of the target process.

7. The CO2 heat pump defrosting control method based on model prediction as described in claim 6, characterized in that, The formula for calculating the fluctuation attenuation coefficient includes: in, For the first The dimensionless fluctuation attenuation coefficient for each monitoring period For sampling period index, The exhaust pressure for the current monitoring period. The exhaust pressure from the previous monitoring period. The exhaust pressure is from the first two monitoring cycles. For the duration of the monitoring period, For the width of the history window, This is the position index within the historical fluctuation window.

8. The CO2 heat pump defrosting control method based on model prediction as described in claim 1, characterized in that, Based on the defrosting mode, the defrosting progress index of the target process is determined according to the time relationship between the time of the extreme point of the heat exchanger outlet temperature in the target process and the time when the compressor suction pressure falls to the saturation pressure value corresponding to the current ambient temperature in the target process, including: Based on the defrosting mode, record the peak operating temperature of the heat exchanger outlet and the corresponding peak time during the target process; The moment when the compressor suction pressure changes from decreasing to increasing during the target process is taken as the pressure recovery moment of the target process. When the peak time is earlier than the pressure recovery time, the initial defrosting phase indicator of the target process is obtained; When the peak moment and the pressure recovery moment are both recorded in the target process record, the defrosting end point identifier of the target process is obtained; The initial defrosting indicator and the final defrosting indicator are combined to form the defrosting progress index of the target process.

9. The CO2 heat pump defrosting control method based on model prediction as described in claim 1, characterized in that, The step of adjusting the opening degree of key valves and compressor frequency of the target process according to the defrosting progress index to obtain the heating recovery command of the target process includes: The opening degree of the key valve corresponding to the initial defrosting indicator in the defrosting progress index is taken as the recovery target opening degree of the target process, and the corresponding compressor frequency is taken as the recovery target frequency of the target process. Based on the defrosting end-of-defrosting indicator in the defrosting progress index, the opening degree of the key valve and the compressor frequency are successively approximated to the recovery target opening degree and the recovery target frequency to obtain the test sequence of the target process; When the real-time deviation value in each consecutive period of the test sequence is not greater than the previous deviation value, the heating recovery command of the target process is obtained.

10. A model-predictive CO2 heat pump defrosting control system, used to implement the model-predictive CO2 heat pump defrosting control method according to any one of claims 1-9, characterized in that, The system includes: The frosting assessment module collects heating operation data of the target process and determines the frosting impact assessment coefficient of the target process based on the degree of deviation between the actual heat exchange temperature difference and the theoretical heat exchange temperature difference in the heating operation data. The defrosting start-up module identifies the defrosting deterioration period of the target process based on the changing trend of the defrosting impact assessment coefficient, and locates the turning point where the rate of change of return water temperature in the heating operation data changes from positive to negative within the defrosting deterioration period, thereby obtaining the defrosting start-up identifier of the target process. The modulation sequence module sequentially configures the opening degree of key valves and the frequency of the compressor in the target process based on the state parameters of the defrost start identifier, thereby obtaining the valve modulation sequence and compressor modulation sequence of the target process; The defrosting module is switched to drive the actuator of the target process according to the valve modulation sequence and the compressor modulation sequence, and the defrosting mode of the target process is switched when the exhaust pressure of the actuator reaches the transition equilibrium point of the target process. The progress indicator module, based on the defrosting mode, determines the defrosting progress indicator of the target process according to the temporal relationship between the time of the extreme point of the heat exchanger outlet temperature in the target process and the time when the compressor suction pressure falls to the saturation pressure value corresponding to the current ambient temperature in the target process. The heating recovery module adjusts the opening degree of key valves and compressor frequency of the target process according to the defrosting progress index to obtain the heating recovery command of the target process.

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