Control method and device of carbon dioxide heat pump system and electronic equipment

Abstract

The application discloses a control method and device of a carbon dioxide heat pump system, electronic equipment and a computer storage medium, and is applied to the carbon dioxide heat pump system comprising a carbon dioxide circulation loop and a heating water circuit. The method comprises the following steps: determining a first preset difference range between an inlet air temperature and an outlet water temperature according to a target outlet water temperature; increasing the working frequency of a compressor in the case that the first temperature difference between the inlet air temperature and the outlet water temperature is less than the lower limit of the first preset difference range, and the first error value between the lower limit of the first preset difference range and the first temperature difference exceeds the first preset error value; and reducing the working frequency of the compressor in the case that the first temperature difference is greater than the upper limit of the first preset difference range, and the second error value between the first temperature difference and the upper limit of the first preset difference range exceeds the second preset error value. The control process can ensure that the outlet water temperature reaches the target outlet water temperature, and the system has a high energy efficiency ratio.

Description

Technical Field

[0001] This application relates to the field of heat pump manufacturing, and more particularly to a control method, apparatus, electronic device, and computer storage medium for a carbon dioxide heat pump system. Background Technology

[0002] A carbon dioxide heat pump system is a high-efficiency heat pump system that uses carbon dioxide (CO2, R744) as a refrigerant. In the heat pump system, carbon dioxide undergoes four basic processes: evaporation, compression, cooling, and expansion, thereby absorbing heat from the low-temperature environment, raising it to a higher temperature, and then releasing that heat. For example, a carbon dioxide heat pump water heater uses carbon dioxide to absorb heat from the low-temperature air, compress it to a higher temperature, and then release that heat to heat the water.

[0003] Since carbon dioxide heat pump systems utilize the changes in carbon dioxide in a supercritical state to transfer heat, they cannot be controlled based on exhaust superheat and liquid refrigerant subcooling. In other words, traditional heat pump system control methods are no longer applicable to carbon dioxide heat pump systems. Furthermore, existing control methods for carbon dioxide heat pump systems cannot achieve a high Coefficient of Performance (COP) while ensuring the system's heating capacity. Summary of the Invention

[0004] This application provides a control method, apparatus, electronic device, and computer storage medium for a carbon dioxide heat pump system, which ensures the heating capacity of the carbon dioxide heat pump system while enabling it to achieve a high energy efficiency ratio. The above technical solution is as follows:

[0005] In a first aspect, embodiments of this application provide a control method for a carbon dioxide heat pump system. The carbon dioxide heat pump system includes a carbon dioxide circulation loop and a hot water production circuit. The carbon dioxide circulation loop includes a compressor and an air cooler. The first air inlet of the air cooler is connected to the exhaust port of the compressor, and the first water outlet of the air cooler is connected to the outlet of the hot water production circuit. Temperature sensors are installed at both the first air inlet and the first water outlet to detect the inlet air temperature and the outlet water temperature, respectively. The method includes:

[0006] Based on the target outlet water temperature, determine the first preset difference range between the inlet air temperature and the outlet water temperature;

[0007] If the first temperature difference between the inlet air temperature and the outlet water temperature is less than the lower limit of the first preset difference range, and the first error value between the lower limit of the first preset difference range and the first temperature difference exceeds the first preset error value, the operating frequency of the compressor is increased.

[0008] If the first temperature difference is greater than the upper limit of the first preset difference range, and the second error value between the first temperature difference and the upper limit of the first preset difference range exceeds the second preset error value, the operating frequency of the compressor is reduced.

[0009] In one possible implementation, the carbon dioxide circulation loop also includes a regenerator and an expansion valve; the first exhaust port of the air cooler is connected to the high-temperature side inlet of the regenerator, the high-temperature side outlet of the regenerator is connected to the inlet of the expansion valve, and the first water inlet of the air cooler is connected to the water inlet of the hot water circuit; temperature sensors are installed at both the first exhaust port and the first water inlet to detect the exhaust temperature of the first exhaust port and the water inlet temperature of the first water inlet, respectively.

[0010] In one possible implementation, the control method of the above-mentioned carbon dioxide heat pump system further includes: reducing the valve opening of the expansion valve when the second temperature difference between the exhaust temperature and the inlet water temperature falls within any temperature range to be adjusted.

[0011] In one possible implementation, when the first temperature difference between the inlet air temperature and the outlet water temperature is less than the lower limit of a first preset difference range, and the first error value between the lower limit of the first preset difference range and the first temperature difference exceeds the first preset error value, increasing the compressor's operating frequency includes: when the first temperature difference is less than the lower limit of the first preset difference range, and the first error value exceeds the first preset error value, determining a first frequency adjustment amount for the compressor based on the difference between the outlet water temperature and the inlet water temperature, the first error value, and the ambient temperature; and increasing the compressor's operating frequency with the first frequency adjustment amount.

[0012] In one possible implementation, when the first temperature difference is greater than the upper limit of the first preset difference range and the second error value between the first temperature difference and the upper limit of the first preset difference range exceeds the second preset error value, reducing the operating frequency of the compressor includes: when the first temperature difference is greater than the upper limit of the first preset difference range and the second error value exceeds the second preset error value, determining a second frequency adjustment amount for the compressor based on the difference between the outlet water temperature and the inlet water temperature, the second error value, and the ambient temperature; and reducing the operating frequency of the compressor by the second frequency adjustment amount.

[0013] In one possible implementation, when the first temperature difference is less than the lower limit of the first preset difference range and the first error value exceeds the first preset error value, the first frequency adjustment amount of the compressor is determined based on the difference between the outlet water temperature and the inlet water temperature, the first error value, and the ambient temperature. This includes: when the first temperature difference is less than the lower limit of the first preset difference range and the first error value exceeds the first preset error value, controlling the compressor to run at the current operating frequency for a first preset time, and then determining whether the first temperature difference is less than the lower limit of the first preset difference range and whether the first error value exceeds the first preset error value; if so, then determining the first frequency adjustment amount of the compressor based on the difference between the outlet water temperature and the inlet water temperature, the first error value, and the ambient temperature.

[0014] In one possible implementation, when the first temperature difference is greater than the upper limit of the first preset difference range and the second error value exceeds the second preset error value, the second frequency adjustment amount of the compressor is determined based on the difference between the outlet water temperature and the inlet water temperature, the second error value, and the ambient temperature. This includes: when the first temperature difference is greater than the upper limit of the first preset difference range and the second error value exceeds the second preset error value, controlling the compressor to run at the current operating frequency for a second preset time, and then determining whether the first temperature difference is greater than the upper limit of the first preset difference range and whether the second error value exceeds the second preset error value; if so, then determining the second frequency adjustment amount of the compressor based on the difference between the outlet water temperature and the inlet water temperature, the second error value, and the ambient temperature.

[0015] In one possible implementation, when the second temperature difference between the exhaust temperature and the inlet water temperature falls within any adjustable temperature range, reducing the valve opening of the expansion valve includes: determining the valve opening adjustment amount corresponding to any adjustable temperature range when the second temperature difference falls within any adjustable temperature range; different adjustable temperature ranges correspond to different valve opening adjustment amounts; and reducing the valve opening of the expansion valve by the valve opening adjustment amount.

[0016] In one possible implementation, when the second temperature difference belongs to any temperature range to be adjusted, determining the valve opening adjustment amount corresponding to any temperature range to be adjusted includes: when the second temperature difference belongs to any temperature range to be adjusted, controlling the expansion valve to maintain the current valve opening for a third preset time, and then determining whether the second temperature difference belongs to any temperature range to be adjusted; if so, determining the valve opening adjustment amount corresponding to any temperature range to be adjusted.

[0017] In one possible implementation, the control method of the above-mentioned carbon dioxide heat pump system further includes: if the second temperature difference between the exhaust temperature and the inlet water temperature exceeds a second preset difference range, determining whether the outlet water temperature is less than the target outlet water temperature and whether the error value between the outlet water temperature and the target outlet water temperature is greater than a preset error value; if so, increasing the operating frequency of the compressor and / or decreasing the valve opening of the expansion valve; if not, decreasing the operating frequency of the compressor and / or increasing the valve opening of the expansion valve.

[0018] Secondly, embodiments of this application provide a control device for a carbon dioxide heat pump system. The carbon dioxide heat pump system includes a carbon dioxide circulation loop and a hot water production circuit. The carbon dioxide circulation loop includes a compressor and an air cooler. The first air inlet of the air cooler is connected to the exhaust port of the compressor, and the first water outlet of the air cooler is connected to the outlet of the hot water production circuit. Temperature sensors are installed at both the first air inlet and the first water outlet to detect the inlet air temperature and the outlet water temperature, respectively. The device includes:

[0019] The range determination module is used to determine a first preset difference range between the air inlet temperature and the water outlet temperature based on the target water outlet temperature.

[0020] The frequency increase control module is used to increase the operating frequency of the compressor when the first temperature difference between the inlet air temperature and the outlet water temperature is less than the lower limit of the first preset difference range, and the first error value between the lower limit of the first preset difference range and the first temperature difference exceeds the first preset error value.

[0021] The frequency reduction control module is used to reduce the operating frequency of the compressor when the first temperature difference is greater than the upper limit of the first preset difference range and the second error value between the first temperature difference and the upper limit of the first preset difference range exceeds the second preset error value.

[0022] Thirdly, embodiments of this application provide an electronic device, including: a processor and a memory; wherein the memory stores a computer program, the computer program being adapted to be loaded by the processor and executed by the method steps provided in the first aspect of embodiments of this application.

[0023] Fourthly, embodiments of this application provide a computer storage medium storing multiple instructions adapted for loading and executing the method steps provided in the first aspect of embodiments of this application by a processor.

[0024] The aforementioned control method, device, electronic equipment, and computer storage medium for a carbon dioxide heat pump system are applied to a carbon dioxide heat pump system including a carbon dioxide circulation loop and a hot water circuit. The carbon dioxide circulation loop includes a compressor and an air cooler. The first air inlet of the air cooler is connected to the compressor's exhaust port, and the first water outlet of the air cooler is connected to the outlet of the hot water circuit. Temperature sensors are installed at both the first air inlet and the first water outlet to detect the inlet air temperature and the outlet water temperature, respectively. During the control of the carbon dioxide heat pump system, an ideal first preset difference range between the inlet air temperature and the outlet water temperature is determined based on the target outlet water temperature. When the first temperature difference between the inlet air temperature and the outlet water temperature is less than the lower limit of the first preset difference range, and the first error value between the lower limit of the first preset difference range and the first temperature difference exceeds the first preset error value, the refrigerant circulation volume of the system is increased by increasing the compressor's operating frequency, thereby enhancing the heat exchange capacity of the air cooler and ensuring that the outlet water temperature at the first outlet reaches the target outlet water temperature. When the first temperature difference exceeds the upper limit of the first preset difference range, and the second error value between the first temperature difference and the upper limit of the first preset difference range exceeds the second preset error value, the refrigerant circulation volume of the system is reduced by decreasing the compressor's operating frequency. This avoids insufficient heat exchange in the air cooler and ensures the carbon dioxide heat pump system has a high energy efficiency ratio. Throughout the control process of the entire carbon dioxide heat pump system, the first temperature difference between the inlet air temperature and the outlet water temperature is used as the control variable. When the first temperature difference does not fall within the first preset difference range, the operating frequency of the compressor is increased or decreased to control the carbon dioxide heat pump system, ensuring that the outlet water temperature reaches the target outlet water temperature while maintaining a high energy efficiency ratio. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A schematic diagram illustrating an application scenario of a control method for a carbon dioxide heat pump system provided as an exemplary embodiment of this application;

[0027] Figure 2 A schematic diagram illustrating the application environment of a control method for a carbon dioxide heat pump system provided as an exemplary embodiment of this application;

[0028] Figure 3 A schematic flowchart illustrating a control method for a carbon dioxide heat pump system provided as an exemplary embodiment of this application;

[0029] Figure 4 A schematic flowchart of another control method for a carbon dioxide heat pump system provided as an exemplary embodiment of this application;

[0030] Figure 5 A schematic flowchart of another control method for a carbon dioxide heat pump system provided as an exemplary embodiment of this application;

[0031] Figure 6 A schematic diagram of valve opening control for an expansion valve provided as an exemplary embodiment of this application;

[0032] Figure 7 A schematic diagram of the structure of a control device for a carbon dioxide heat pump system provided as an exemplary embodiment of this application;

[0033] Figure 8 This is a schematic diagram of the structure of an electronic device provided as an exemplary embodiment of this application. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0035] In the description of this application, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. Furthermore, in the description of this application, unless otherwise stated, "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship.

[0036] Please see Figure 1 First, let's introduce an application scenario applicable to the embodiments of this application: a carbon dioxide heat pump system 10 applied to a high-temperature water heater includes a carbon dioxide circulation loop 11, a hot water production line 12, and a bypass branch 13. The carbon dioxide circulation loop 11 and the bypass branch 13 are used for the circulation of carbon dioxide, and the hot water production line 13 is used for the circulation of water. The carbon dioxide circulation loop 11 is equipped with an evaporator 1, a regenerator 2, a compressor 3, an air cooler 4, and an expansion valve 5. The bypass branch 13 is equipped with a bypass valve 6 and a capillary tube 7. The hot water production line 12 has an inlet 8 and an outlet 9.

[0037] The carbon dioxide outlet of evaporator 1 is connected sequentially to regenerator 2, compressor 3, and air cooler 4 via pipelines, and then connected to expansion valve 5 via regenerator 2. Expansion valve 5 is then connected back to the carbon dioxide inlet of evaporator 1 via pipelines, thus forming a carbon dioxide circulation loop 11. Specifically, the carbon dioxide outlet of evaporator 1 is connected to the low-temperature inlet of regenerator 2 via pipelines; the low-temperature outlet of regenerator 2 is connected to the return port of compressor 3 via pipelines; the exhaust port of compressor 3 is connected to the first inlet 41 of air cooler 4 via pipelines; the first exhaust port 42 of air cooler 4 is connected to the high-temperature inlet of regenerator 2 via pipelines; and the high-temperature outlet of regenerator 2 is connected to the inlet of expansion valve 5 via pipelines, and then connected back to the carbon dioxide inlet of evaporator 1 via the outlet of expansion valve 5. A bypass branch 13, formed by bypass valve 6 and capillary tube 7 connected in series, is connected to carbon dioxide circulation loop 11, with one end of bypass branch 13 connected to the exhaust port of compressor 3 via pipelines, and the other end connected to the carbon dioxide inlet of evaporator 5 via pipelines.

[0038] The inlet 8 and outlet 9 of the hot water circuit 12 are connected to the first inlet 43 and the first outlet 44 of the air cooler 4, respectively, so that the carbon dioxide circulation loop 11 and the hot water circuit 12 can exchange heat through the air cooler 4. That is, the air cooler 4 includes a portion of the carbon dioxide circulation loop 11 located between the first air inlet 41 and the first exhaust port 42, and a portion of the hot water circuit 12 located between the first inlet 43 and the first outlet 44.

[0039] The working process of the carbon dioxide heat pump system 10 is as follows: The carbon dioxide working fluid absorbs heat in the evaporator 1 and becomes low-temperature carbon dioxide vapor. It then enters the low-temperature inlet of the regenerator 2, where it exchanges heat with the high-temperature carbon dioxide vapor returning from the air cooler 4, forming preheated carbon dioxide vapor. The preheated carbon dioxide vapor enters the return port of the compressor 3 from the low-temperature outlet of the regenerator 2, where it is compressed into high-temperature, high-pressure carbon dioxide vapor. The high-temperature, high-pressure carbon dioxide vapor flows out from the exhaust port of the compressor 3 and enters the first inlet 41 of the air cooler 4, where it releases a large amount of heat to heat the water entering from the first inlet 43. The heated water flows out from the first outlet 44, and the cooled high-temperature, high-pressure carbon dioxide vapor returns from the high-temperature inlet of the regenerator 2 to reheat, then flows out from the high-temperature outlet of the regenerator 2 and returns to the evaporator 1 through the expansion valve 5, thus completing one cycle. In defrost mode, bypass valve 6 is opened, allowing some of the high-temperature gas passing through compressor 3 to enter evaporator 1 for defrosting after the flow and pressure are regulated by capillary tube 7.

[0040] Furthermore, the carbon dioxide heat pump system 10 also includes a temperature sensor for detecting the evaporation temperature in the evaporator 1, the air inlet temperature of the first air inlet 41, the exhaust temperature of the first exhaust port 42, the water inlet temperature of the first water inlet 43, the water outlet temperature of the first water outlet 44, and the ambient temperature, etc.

[0041] It is worth noting that this embodiment only describes a preferred application scenario of this application. This application does not impose any restrictions on the specific structure, location, or number of components in the carbon dioxide heat pump system 10 (including but not limited to the evaporator 1, regenerator 2, compressor 3, air cooler 4, expansion valve 5, temperature sensor, etc.). Those skilled in the art can set them according to the actual situation.

[0042] The control method for the carbon dioxide heat pump system provided in this application embodiment can be applied to, for example... Figure 2 In the application environment shown, the controller 20 communicates with the carbon dioxide heat pump system 10 to ensure that the outlet water temperature reaches the target outlet water temperature while maintaining a high energy efficiency ratio. Specifically, the controller 20 determines a first preset difference range between the inlet air temperature and the outlet water temperature based on the target outlet water temperature. If the first temperature difference between the inlet air temperature and the outlet water temperature is less than the lower limit of the first preset difference range, and the first error value between the lower limit of the first preset difference range and the first temperature difference exceeds the first preset error value, the controller 20 increases the operating frequency of the compressor 3. If the first temperature difference is greater than the upper limit of the first preset difference range, and the second error value between the first temperature difference and the upper limit of the first preset difference range exceeds the second preset error value, the controller 20 decreases the operating frequency of the compressor 3. The controller 20 can at least obtain the detection results uploaded by the temperature sensor in the carbon dioxide heat pump system 10 and control the operating frequency of the compressor 3 and the valve opening of the expansion valve 5 based on the detection results uploaded by the temperature sensor; this application does not limit this to a specific parameter. It is understood that the controller 20 can be either the original controller of the carbon dioxide heat pump system 10 or a controller separately set up to execute the control method of the carbon dioxide heat pump system of this application. Those skilled in the art can set the structure and model of the controller 20 according to actual usage requirements.

[0043] In one embodiment, such as Figure 3 As shown, a control method for a carbon dioxide heat pump system is provided, which is applied to... Figure 2 Taking controller 20 as an example, combined with Figure 1 The carbon dioxide heat pump system 10 shown is described, including the following steps:

[0044] S301: Determine the first preset difference range between the air inlet temperature and the water outlet temperature based on the target outlet water temperature.

[0045] The inlet air temperature is the temperature detected in real time by a temperature sensor at the first air inlet 41 of the air cooler 4, and the outlet water temperature is the temperature detected in real time by a temperature sensor at the first water outlet 44 of the air cooler 4. The first preset difference range between the inlet air temperature and the outlet water temperature is an ideal difference range measured experimentally. Maintaining the difference between the inlet water temperature and the outlet water temperature within this first preset difference range ensures that the outlet water temperature at the first outlet 44 reaches the target outlet water temperature while the carbon dioxide heat pump system 10 has a high energy efficiency ratio. The correspondence between the first preset difference range and the target outlet water temperature is shown in Table 1.

[0046] Table 1. Relationship between the first preset difference range and the target outlet water temperature.

[0047]

[0048] As shown in Table 1, when the target outlet water temperature is between 55℃ and 70℃, the first preset difference between the inlet air temperature and the outlet water temperature is 22℃-25℃; when the target outlet water temperature is between 70℃ and 90℃, the first preset difference between the inlet air temperature and the outlet water temperature is 25℃-30℃.

[0049] For example, if a user sets the target outlet water temperature of the carbon dioxide heat pump system 10 to 60°C, or sets the target outlet water temperature between 50°C and 60°C, then the controller 20 determines that the first preset difference range between the inlet air temperature and the outlet water temperature is 22°C to 25°C. If a user sets the target outlet water temperature of the carbon dioxide heat pump system 10 to 80°C, or sets the target outlet water temperature between 75°C and 85°C, then the controller 20 determines that the first preset difference range between the inlet air temperature and the outlet water temperature is 26°C to 30°C.

[0050] S302: When the first temperature difference between the inlet air temperature and the outlet water temperature is less than the lower limit of the first preset difference range, and the first error value between the lower limit of the first preset difference range and the first temperature difference exceeds the first preset error value, the operating frequency of the compressor is increased.

[0051] The first preset error value is a pre-set error threshold, such as 1℃, and can be adjusted according to actual needs, such as 2℃, 5℃, etc. The smaller the first preset error value is set, the smaller the deviation between the system's acceptable first temperature difference and the lower limit of the first preset difference range.

[0052] Optionally, if the first temperature difference between the inlet air temperature and the outlet water temperature is less than the lower limit of the first preset difference range, and the first error value between the lower limit of the first preset difference range and the first temperature difference exceeds the first preset error value (e.g., 1°C), then the temperature difference between the refrigerant (carbon dioxide gas) before entering the air cooler 4 and the water temperature after being heated by the air cooler 4 is too small, which means that the heat exchange capacity of the air cooler 4 is insufficient. In this case, it is necessary to increase the operating frequency of the compressor 3 to accelerate the circulation speed of the refrigerant in the carbon dioxide heat pump system 10, thereby ensuring that more refrigerant flows through the air cooler 4 and exchanges heat with the water per unit time, thereby enhancing the heat exchange capacity of the air cooler 4.

[0053] S303: If the first temperature difference is greater than the upper limit of the first preset difference range and the second error value between the first temperature difference and the upper limit of the first preset difference range exceeds the second preset error value, reduce the operating frequency of the compressor.

[0054] The second preset error value is a pre-set error threshold. This second preset error value can be the same as or different from the first preset error value. For example, the second preset error value can be set to 1℃, and can also be adjusted according to actual needs, such as to 2℃, 5℃, etc. The smaller the second preset error value is set, the smaller the deviation between the system's acceptable first temperature difference and the upper limit of the first preset difference range.

[0055] Optionally, if the first temperature difference between the inlet air temperature and the outlet water temperature is greater than the upper limit of the first preset difference range, and the second error value between the first temperature difference and the upper limit of the first preset difference range exceeds the second preset error value, then the temperature difference between the refrigerant before entering the air cooler 4 and the water temperature after being heated by the air cooler 4 is too large. This means that the refrigerant is not sufficiently cooled in the air cooler 4, and the heat exchange efficiency of the air cooler 4 is low. At this time, it is necessary to reduce the operating frequency of the compressor 3 to reduce the circulation speed of the refrigerant in the carbon dioxide heat pump system 10, thereby ensuring that the time for heat exchange between a unit mass of refrigerant and water in the air cooler 4 is extended, avoiding the problem of insufficient heat exchange caused by excessive refrigerant circulation, thereby improving the energy efficiency ratio of the carbon dioxide heat pump system 10.

[0056] In the control method of the aforementioned carbon dioxide heat pump system, the controller determines an ideal first preset difference range between the inlet air temperature and the outlet water temperature based on the target outlet water temperature. When the first temperature difference between the inlet air temperature and the outlet water temperature is less than the lower limit of the first preset difference range, and the first error value between the lower limit of the first preset difference range and the first temperature difference exceeds the first preset error value, the controller increases the compressor's operating frequency to increase the refrigerant circulation volume of the system, thereby enhancing the heat exchange capacity of the air cooler and ensuring that the outlet water temperature at the first outlet reaches the target outlet temperature. When the first temperature difference is greater than the upper limit of the first preset difference range, and the second error value between the first temperature difference and the upper limit of the first preset difference range exceeds the second preset error value, the controller decreases the compressor's operating frequency to reduce the refrigerant circulation volume of the system, thereby avoiding insufficient heat exchange in the air cooler and enabling the carbon dioxide heat pump system to have a high energy efficiency ratio. The entire control process of the carbon dioxide heat pump system uses the first temperature difference between the inlet air temperature and the outlet water temperature as the control variable. When the first temperature difference does not fall within the first preset difference range, the carbon dioxide heat pump system is controlled by increasing or decreasing the operating frequency of the compressor to ensure that the outlet water temperature reaches the target outlet water temperature while the carbon dioxide heat pump system has a high energy efficiency ratio.

[0057] In one embodiment, such as Figure 4 As shown, another control method for a carbon dioxide heat pump system is provided, which can be applied to... Figure 2 Taking controller 20 as an example, combined with Figure 1 The carbon dioxide heat pump system 10 shown is described, including the following steps:

[0058] S401: Determine the first preset difference range between the air inlet temperature and the water outlet temperature based on the target outlet water temperature.

[0059] Specifically, S401 is the same as S301, and will not be repeated here.

[0060] S402: Controls the compressor to operate at the initial frequency.

[0061] Optionally, the initial frequency of compressor 3 can be calculated by back-calculating from the target heating capacity of carbon dioxide heat pump system 10, taking into account the ambient temperature surrounding carbon dioxide heat pump system 10. First, the evaporation temperature of evaporator 14 is determined based on the ambient temperature during operation of carbon dioxide heat pump system 10 and the estimated heat exchange temperature difference. The return gas density of carbon dioxide gas is determined using the evaporation temperature and the equation of state for carbon dioxide gas. Then, the estimated demand for carbon dioxide flow rate of carbon dioxide heat pump system 10 is calculated based on the target heating capacity and the estimated specific enthalpy difference between the first inlet 41 and the first outlet 42. Finally, the initial frequency of compressor 3 is calculated based on the estimated demand for carbon dioxide flow rate, the discharge volume of compressor 3, the return gas density of carbon dioxide gas, and the volumetric efficiency of compressor 3. Operating at the calculated initial frequency allows the carbon dioxide heat pump system to achieve the target heating capacity while maintaining a high energy efficiency ratio. Assuming a heat exchange temperature difference of 5℃, the specific calculation formula for the initial frequency of compressor 3 is as follows:

[0062]

[0063] Among them, T eva T1 is the evaporation temperature of evaporator 13, T4 is the ambient temperature during operation of carbon dioxide heat pump system 10, and T5 is the evaporation temperature of evaporator 13. eva Both T4 and T4 are in degrees Celsius (°C). ρ hq The density of carbon dioxide gas is expressed in kilograms per cubic meter (kg / m³). 3 ), F(T eva This refers to determining the return gas density of carbon dioxide gas using the equation of state for carbon dioxide gas. (m) ref Q represents the estimated carbon dioxide flow rate required by the carbon dioxide heat pump system 10, expressed in kilograms per second (kg / s); a The target heating capacity of the carbon dioxide heat pump system 10 is expressed in kilowatts (kW); h ref_in h is the estimated specific enthalpy of carbon dioxide gas at the first inlet 41. ref_out h is the estimated specific enthalpy of carbon dioxide gas at the first exhaust port 42. ref_in and h ref_out The units are all kilojoules per kilogram (kJ / kg). f is the initial operating frequency of compressor 3, and its unit is Hertz (Hz); v is the discharge capacity of compressor 3, and its unit is cubic meters (m³). 3 );η v The volumetric efficiency η of compressor 3 v The empirical coefficient is 0.9.

[0064] S403: When the first temperature difference is less than the lower limit of the first preset difference range and the first error value exceeds the first preset error value, the first frequency adjustment amount of the compressor is determined based on the difference between the outlet water temperature and the inlet water temperature, the first error value and the ambient temperature.

[0065] Optionally, if the first temperature difference between the inlet air temperature and the outlet water temperature is less than the lower limit of the first preset difference range (22℃ or 26℃) shown in Table 1, and the first error value ΔT1 between the lower limit of the first preset difference range and the first temperature difference exceeds the first preset error value (1℃), the controller 20 determines the first frequency adjustment amount of the compressor 3 by referring to a table based on the difference between the outlet water temperature of the first outlet 44 and the inlet water temperature of the first inlet 43 (inlet-outlet water temperature difference), the first error value ΔT1, and the ambient temperature around the carbon dioxide heat pump system 10. Specifically, when the inlet-outlet water temperature difference is between 20℃ and 30℃, the first frequency adjustment amount is determined by referring to Table 2, combining the first error value ΔT1 and the ambient temperature; when the inlet-outlet water temperature difference is between 40℃ and 60℃, the first frequency adjustment amount is determined by referring to Table 3, combining the first error value ΔT1 and the ambient temperature. Tables 2-3 are shown below:

[0066] Table 2. Relationship between initial frequency, first error value, and ambient temperature (inlet / outlet water temperature difference: 20℃-30℃)

[0067]

[0068] Table 3. Relationship between initial frequency, first error value, and ambient temperature (inlet / outlet water temperature difference: 40℃-60℃)

[0069]

[0070]

[0071] For example, assuming the ambient temperature is 20℃, and the first temperature difference between the inlet air temperature and the outlet water temperature is 18℃, the first error value ΔT1 is determined by referring to Table 1 as 22℃ - 18℃ = 4℃ ∈ (3,5). If the difference between the outlet water temperature of the first outlet 44 and the inlet water temperature of the first inlet 43 is 25℃, then the first frequency adjustment is determined to be 0Hz (maintaining the current operating frequency) by referring to Table 2. If the difference between the outlet water temperature of the first outlet 44 and the inlet water temperature of the first inlet 43 is 50℃, then the first frequency adjustment is determined to be 1Hz by referring to Table 3.

[0072] S404: Increase the compressor's operating frequency by adjusting the first frequency.

[0073] Understandably, if the first temperature difference is less than the lower limit of the first preset difference range (22℃ or 26℃) and the first error value exceeds the first preset error value (1℃), it means that the temperature difference between the refrigerant before entering the air cooler 4 and the water temperature after being heated by the air cooler 4 is too small, and the heat exchange capacity of the air cooler 4 is insufficient. At this time, it is necessary to increase the operating frequency of the compressor 3 according to the first frequency adjustment amount, that is, increase the current operating frequency of the compressor 3 by the first frequency adjustment amount (such as 1Hz), so as to ensure that more refrigerant flows through the air cooler 4 and exchanges heat with the water per unit time, thereby enhancing the heat exchange capacity of the air cooler 4.

[0074] S405: When the first temperature difference is greater than the upper limit of the first preset difference range and the second error value between the first temperature difference and the upper limit of the first preset difference range exceeds the second preset error value, the second frequency adjustment amount of the compressor is determined based on the difference between the outlet water temperature and the inlet water temperature, the second error value and the ambient temperature.

[0075] Optionally, if the first temperature difference between the inlet air temperature and the outlet water temperature is greater than the upper limit of the first preset difference range (25℃ or 30℃) as shown in Table 1, and the second error value ΔT1' between the first temperature difference and the upper limit of the first preset difference range exceeds the second preset error value (1℃), the controller 20 determines the second frequency adjustment amount of the compressor 3 by referring to a table based on the difference between the outlet water temperature of the first outlet 44 and the inlet water temperature of the first inlet 43 (inlet-outlet water temperature difference), the second error value ΔT1', and the ambient temperature around the carbon dioxide heat pump system 10. Specifically, when the inlet-outlet water temperature difference is between 20℃ and 30℃, the first frequency adjustment amount is determined by referring to Table 4 in combination with the second error value ΔT1' and the ambient temperature; when the inlet-outlet water temperature difference is between 40℃ and 60℃, the second frequency adjustment amount is determined by referring to Table 5 in combination with the second error value ΔT1' and the ambient temperature. Tables 4-5 are shown below:

[0076] Table 4. Relationship between initial frequency, second error value, and ambient temperature (inlet / outlet water temperature difference: 20℃-30℃)

[0077]

[0078]

[0079] Table 5. Relationship between initial frequency, second error value, and ambient temperature (inlet / outlet water temperature difference: 40℃-60℃)

[0080]

[0081] For example, assuming the ambient temperature is 20℃, and the first temperature difference between the inlet air temperature and the outlet water temperature is 30℃, the second error value ΔT1′ = 30℃ - 25℃ = 5℃ ∈ (3℃, 5℃) is determined according to Table 1. If the difference between the outlet water temperature of the first outlet 44 and the inlet water temperature of the first inlet 43 is 25℃, then the second frequency adjustment is determined to be 0Hz (maintaining the current operating frequency) according to Table 4. If the difference between the outlet water temperature of the first outlet 44 and the inlet water temperature of the first inlet 43 is 50℃, then the second frequency adjustment is determined to be 1Hz according to Table 5.

[0082] S406: Reduce the compressor's operating frequency using the second frequency adjustment amount.

[0083] Understandably, if the first temperature difference exceeds the upper limit of the first preset difference range (25℃ or 30℃) and the second error value exceeds the second preset error value (1℃), it means that the temperature of the refrigerant before entering the air cooler 4 is too different from the temperature of the water after being heated by the air cooler 4, and the refrigerant is not sufficiently cooled in the air cooler 4. At this time, it is necessary to reduce the operating frequency of the compressor 3 according to the second frequency adjustment amount, that is, reduce the current operating frequency of the compressor 3 by the second frequency adjustment amount (such as 1Hz), so as to ensure that the time for heat exchange between the unit mass of refrigerant and water in the air cooler 4 is extended, avoiding the problem of insufficient heat exchange caused by excessive refrigerant circulation, thereby improving the energy efficiency ratio of the carbon dioxide heat pump system 10.

[0084] S407: If the second temperature difference between the exhaust temperature and the inlet water temperature falls within any of the temperature ranges to be adjusted, reduce the valve opening of the expansion valve.

[0085] Optionally, if the second temperature difference T2 between the exhaust temperature and the inlet water temperature falls within any of the temperature ranges to be adjusted as shown in Table 6 (i.e., the second temperature difference T2 is greater than or equal to 3℃), the valve opening adjustment amount corresponding to any temperature range to be adjusted is determined, and the valve opening of the expansion valve is reduced by the valve opening adjustment amount. The valve opening adjustment amount is expressed in valve steps, and the valve opening adjustment amount varies for different temperature ranges to be adjusted. Table 6 is shown below:

[0086] Table 6. Relationship between valve opening adjustment and second temperature difference.

[0087]

[0088]

[0089] For example, if the second temperature difference T2 between the exhaust temperature and the inlet water temperature is 6°C, the valve's opening change is two steps, meaning the expansion valve 5 is adjusted by twice the minimum adjustment unit (e.g., 5% of the opening size). If the second temperature difference T2 between the exhaust temperature and the inlet water temperature is 8°C, the valve's opening change is five steps, meaning the expansion valve 5 is adjusted by five times the minimum adjustment unit. If the second temperature difference T2 between the exhaust temperature and the inlet water temperature is 8°C, the valve's opening change is one step, meaning the expansion valve 5 is adjusted by the minimum adjustment unit.

[0090] In this embodiment, the controller controls the compressor to operate at an initial frequency calculated by back-calculating the ambient temperature and the target heating capacity of the carbon dioxide heat pump system. During the operation of the carbon dioxide heat pump system, the first temperature difference between the inlet air temperature and the outlet water temperature of the air cooler, and the second temperature difference between the exhaust temperature and the inlet water temperature of the air cooler are used as control variables. When the first temperature difference is not within the first preset difference range or differs significantly from it, the operating frequency of the compressor is increased or decreased to control the carbon dioxide heat pump system. When the second temperature difference is within the temperature range to be adjusted, the opening of the expansion valve is decreased to control the carbon dioxide heat pump system. The entire control process of the carbon dioxide heat pump system combines initial frequency control, real-time temperature detection, frequency control adjustment, and valve control adjustment to ensure that the carbon dioxide heat pump system achieves a high energy efficiency ratio while reaching the target heating capacity.

[0091] In one embodiment, such as Figure 5 As shown, another control method for a carbon dioxide heat pump system is provided, which can be applied to... Figure 2 Taking controller 20 as an example, combined with Figure 1 The carbon dioxide heat pump system 10 shown is described, including the following steps:

[0092] S501: Determine the first preset difference range between the air inlet temperature and the water outlet temperature based on the target outlet water temperature.

[0093] Specifically, S501 is the same as S301, and will not be repeated here.

[0094] S502: Controls the compressor to operate at the initial frequency.

[0095] Specifically, S502 is the same as S402, and will not be repeated here.

[0096] S503: Determine whether the first temperature difference exceeds the first preset difference range. If yes, execute S504; if no, execute S517.

[0097] Optionally, based on the target outlet water temperature of the carbon dioxide heat pump system 10, refer to Table 1 to determine whether the first temperature difference between the inlet air temperature of the first air inlet 41 and the outlet water temperature of the first water outlet 44 exceeds a first preset difference range. That is, when the target outlet water temperature of the carbon dioxide heat pump system 10 is between 55℃ and 70℃, determine whether the first temperature difference exceeds 22℃-25℃; when the target outlet water temperature of the carbon dioxide heat pump system 10 is between 70℃ and 90℃, determine whether the first temperature difference exceeds 26℃-30℃.

[0098] S504: Determine whether the first temperature difference is less than the lower limit of the first preset difference range. If yes, execute S505; if no, execute S511.

[0099] Optionally, if the first temperature difference exceeds a first preset difference range, it is further determined whether the first temperature difference is less than the lower limit of the first preset difference range. That is, when the target outlet water temperature of the carbon dioxide heat pump system 10 is between 55℃ and 70℃, it is determined whether the first temperature difference is less than 22℃; when the target outlet water temperature of the carbon dioxide heat pump system 10 is between 70℃ and 90℃, it is determined whether the first temperature difference is less than 26℃.

[0100] S505: Determine whether the first error value exceeds the first preset error value. If yes, execute S506; otherwise, return to S503 above.

[0101] Optionally, if the first temperature difference is less than the lower limit of the first preset difference range, it is further determined whether the first error value between the lower limit of the first preset difference range and the first temperature difference exceeds the first preset error value (1℃).

[0102] S506: Control the compressor to run at the current operating frequency for a first preset duration.

[0103] The first preset duration is a pre-set stability confirmation period used to verify whether the compressor 3 still meets the frequency increase conditions after running at the current operating frequency for a period of time. The first preset duration can be set to 30 seconds, and can also be adjusted according to actual needs, such as to 20 seconds, 1 minute, etc. The shorter the first preset duration is set, the faster the controller 20 responds to system changes.

[0104] Optionally, if the first temperature difference is still less than the lower limit of the first preset difference range and the first error value still exceeds the first preset error value after the compressor 3 has been running at the current operating frequency for 30 seconds, the controller 20 will execute the operation of increasing the operating frequency of the compressor 3; otherwise, the controller 20 will re-evaluate the conditions to determine whether to maintain the current operating state of the system.

[0105] In this embodiment, controlling the compressor to run at the current operating frequency for a first preset duration can effectively ensure that the system has reached a stable state before the controller adjusts the compressor frequency, avoiding unnecessary frequency adjustments caused by short-term external interference or system instability, and enhancing the robustness of control and the operating efficiency of the system.

[0106] S507: Determine whether the first error value exceeds the first preset error value. If yes, execute S508; otherwise, return to S503 above.

[0107] Optionally, after the controller 20 controls the compressor 3 to run at the current operating frequency for 30 seconds, it again determines whether the first error value exceeds the first preset error value. Only if the first error value exceeds the first preset error value will the controller further determine the first frequency adjustment amount based on the current first error value to increase the operating frequency of the compressor 3; otherwise, it needs to return to S503 to re-evaluate the conditions to determine whether to maintain the current operating state of the system.

[0108] S508: Determine the first frequency adjustment amount of the compressor based on the difference between the outlet water temperature and the inlet water temperature, the first error value, and the ambient temperature.

[0109] For details, please refer to S403, which will not be repeated here.

[0110] S509: Increase the compressor's operating frequency by adjusting the first frequency.

[0111] For details, please refer to S404; it will not be repeated here.

[0112] S510: After controlling the compressor to run at the current operating frequency for a first preset time, return to S503 above.

[0113] Optionally, after the controller 20 controls the compressor 3 to run at the increased operating frequency for 30 seconds, it considers that the system has reached a stable state. At this time, it returns to S503 above and re-evaluates the conditions to determine whether to maintain the current operating state of the system.

[0114] S511: Determine whether the second error value exceeds the second preset error value. If yes, execute S512; otherwise, return to S503 above.

[0115] Optionally, if the first temperature difference exceeds a first preset difference range, and if the first temperature difference is not less than the lower limit of the first preset difference range, then the first temperature difference is greater than the lower limit of the first preset difference range. In this case, the controller 20 determines whether the second error value between the first temperature difference and the upper limit of the first preset difference range exceeds a second preset error value (1°C).

[0116] S512: Controls the compressor to run at the current operating frequency for a second preset duration.

[0117] The second preset duration is a pre-set stability confirmation period used to verify whether the compressor 3 still meets the frequency increase conditions after running at the current operating frequency for a period of time. The second preset duration can be set to 30 seconds, or it can be adjusted according to actual needs, such as to 20 seconds or 1 minute. The shorter the second preset duration is set, the faster the controller 20 responds to system changes.

[0118] Optionally, if the first temperature difference is still greater than the upper limit of the first preset difference range and the second error value still exceeds the second preset error value after the compressor 3 has been running at the current operating frequency for 30 seconds, the controller 20 will execute the operation of reducing the operating frequency of the compressor 3; otherwise, the controller 20 will re-evaluate the conditions to determine whether to maintain the current operating state of the system.

[0119] In this embodiment, controlling the compressor to run at the current operating frequency for a second preset duration can effectively ensure that the system has reached a stable state before the controller adjusts the compressor frequency, avoiding unnecessary frequency adjustments caused by short-term external interference or system instability, and enhancing the robustness of control and the operating efficiency of the system.

[0120] S513: Determine whether the second error value exceeds the second preset error value. If yes, execute S514; otherwise, return to S503 above.

[0121] Optionally, after the controller 20 controls the compressor 3 to run at the current operating frequency for 30 seconds, it again determines whether the second error value exceeds the second preset error value. Only if the second error value exceeds the second preset error value will the second frequency adjustment amount be further determined based on the current second error value to reduce the operating frequency of the compressor 3; otherwise, it is necessary to return to S503 to re-evaluate the conditions to determine whether to maintain the current operating state of the system.

[0122] S514: Determine the second frequency adjustment amount of the compressor based on the difference between the outlet water temperature and the inlet water temperature, the second error value, and the ambient temperature.

[0123] For details, please refer to S405, which will not be repeated here.

[0124] S515: Reduce the compressor's operating frequency using the second frequency adjustment.

[0125] For details, please refer to S406, which will not be repeated here.

[0126] S516: After controlling the compressor to run at the current operating frequency for a second preset time, return to S503 above.

[0127] Optionally, after the controller 20 controls the compressor 3 to run at the reduced operating frequency for 30 seconds, it considers that the system has reached a stable state. At this time, it returns to S503 above and re-evaluates the conditions to determine whether to maintain the current operating state of the system.

[0128] S517: Determine whether the second temperature difference value belongs to any of the temperature ranges to be adjusted. If yes, execute S518; otherwise, return to S503 above.

[0129] Optionally, refer to Table 6 to determine whether the second temperature difference between the exhaust temperature of the first exhaust port 42 and the inlet water temperature of the first inlet water port 43 belongs to any one of the temperature ranges to be adjusted. As shown in Table 6, as long as the second temperature difference T2 is greater than or equal to 3℃, it must belong to one of the three temperature ranges to be adjusted.

[0130] S518: Control the expansion valve to maintain the current valve opening for a third preset duration.

[0131] The third preset duration is a pre-set stabilization confirmation period used to verify whether the expansion valve 5 still meets the valve closing condition after maintaining the current valve opening for a period of time. The third preset duration can be set to 30 seconds, and can also be adjusted according to actual needs, such as to 20 seconds or 1 minute. The shorter the third preset duration is set, the faster the controller 20 responds to system changes.

[0132] Optionally, if the second temperature difference still falls within any of the temperature ranges to be adjusted after the expansion valve 5 has been running at its current operating frequency for 30 seconds, the controller 20 will reduce the valve opening of the expansion valve 5; otherwise, the controller 20 will reassess the conditions to determine whether to maintain the current operating state of the system.

[0133] In this embodiment, controlling the compressor to run at the current operating frequency for a third preset duration can effectively ensure that the system has reached a stable state before the controller adjusts the valve opening of the expansion valve. This avoids unnecessary frequency adjustments caused by short-term external interference or system instability, and enhances the robustness of control and the operating efficiency of the system.

[0134] S519: Determine whether the second temperature difference belongs to any of the temperature ranges to be adjusted. If yes, execute S520; otherwise, return to S503 above.

[0135] Optionally, after the controller 20 controls the expansion valve 5 to maintain the current valve opening for 30 seconds, it re-determines whether the second temperature difference belongs to any of the temperature ranges to be adjusted. Only if the second temperature difference still belongs to any of the temperature ranges to be adjusted, will the valve opening adjustment amount be further determined based on the current second temperature difference to reduce the valve opening of the expansion valve 5; otherwise, it is necessary to return to S503 to re-evaluate the conditions to determine whether to maintain the current operating state of the system.

[0136] S520: Determine the valve opening adjustment amount corresponding to any temperature range to be adjusted.

[0137] Optionally, refer to Table 6 to determine the valve opening adjustment amount corresponding to any temperature range to be adjusted, wherein the valve opening adjustment amount is in valve steps, and the valve opening adjustment amount is different for different temperature ranges to be adjusted.

[0138] As shown in Table 6, when the second temperature difference T2 is greater than or equal to 7℃, the valve opening adjustment amount is 5 steps, that is, the expansion valve 5 is adjusted by five times the minimum adjustment unit (e.g., 5% of the opening size). When the second temperature difference T2 is less than 7℃ but greater than or equal to 5℃, the valve opening adjustment amount is 2 steps, that is, the expansion valve 5 is adjusted by twice the minimum adjustment unit. When the second temperature difference T2 is less than 5℃ but greater than or equal to 3℃, the valve opening adjustment amount is 1 step, that is, the expansion valve 5 is adjusted by the minimum adjustment unit.

[0139] For example, please see Figure 6 Assuming the current second temperature difference T2 is 7℃, the controller 20 will not immediately control the expansion valve to reduce the valve opening. Instead, it will wait for the system to stabilize for 30 seconds before performing a test. Only when the second temperature difference detected after 30 seconds of stabilization still falls within the temperature range of T2 being greater than or equal to 7℃ will the controller 20 obtain the valve opening adjustment amount as 5 steps based on Table 6, and then reduce the valve opening of the expansion valve 5 by five times the minimum adjustment unit of the valve.

[0140] Similarly, assuming the current second temperature difference T2 is 5℃, controller 20 will not immediately control the expansion valve to reduce its opening. Instead, it will wait for the system to stabilize for 30 seconds before detecting the difference. Only if the detected second temperature difference after 30 seconds of stabilization still falls within the temperature range of T2 being less than 7℃ and greater than or equal to 5℃ will controller 20, based on Table 6, obtain the valve opening adjustment amount as 2 steps, and then reduce the valve opening of expansion valve 5 by twice the minimum adjustment unit. Similarly, assuming the current second temperature difference T2 is 3℃, controller 20 will not immediately control the expansion valve to reduce its opening. Instead, it will wait for the system to stabilize for 30 seconds before detecting the difference. Only if the detected second temperature difference after 30 seconds of stabilization still falls within the temperature range of T2 being less than 5℃ and greater than or equal to 3℃ as shown in Table 6 will controller 20, based on Table 6, obtain the valve opening adjustment amount as 1 step, and then reduce the valve opening of expansion valve 5 by the minimum adjustment unit.

[0141] S521: Reduce the valve opening of the expansion valve by adjusting the valve opening amount.

[0142] For details, please refer to S520, which will not be repeated here.

[0143] S522: After the expansion valve maintains the current valve opening for a third preset time, return to the above S503.

[0144] Optionally, after the controller 20 controls the expansion valve 5 to maintain the valve opening at the same level after the valve is closed for 30 seconds, it considers that the system has reached a stable state. At this time, it returns to S503 above and re-evaluates the conditions to determine whether to maintain the current working state of the system.

[0145] In this embodiment, the first temperature difference between the inlet air temperature and the outlet water temperature of the air cooler, and the second temperature difference between the exhaust temperature and the inlet water temperature of the air cooler are used as control variables. When it is determined that the first temperature difference does not belong to the first preset difference range and differs significantly from the first preset difference range, the controller does not immediately perform frequency increase or decrease operation on the compressor. Instead, it controls the compressor to run at the current frequency for a preset time. If the compressor still meets the frequency increase or decrease conditions after running for the preset time, the controller obtains the corresponding frequency adjustment amount according to Table 2-5 and increases or decreases the compressor's operating frequency accordingly. When it is determined that the second temperature difference belongs to any temperature range to be adjusted, the controller does not immediately perform valve closing operation on the expansion valve. Instead, it controls the expansion valve to maintain the current valve opening for a preset time. If the expansion valve still meets the valve closing conditions after maintaining the current valve opening for the preset time, the controller obtains the corresponding valve opening adjustment amount according to Table 6 and decreases the expansion valve's valve opening accordingly. The entire control process of the carbon dioxide heat pump system not only ensures that the carbon dioxide heat pump system has a high energy efficiency ratio while achieving the target heating capacity, but also effectively ensures that the system has reached a stable state before the controller adjusts the compressor or expansion valve. This avoids unnecessary frequency adjustments caused by short-term external interference or system instability, and enhances the robustness of the control and the operating efficiency of the system.

[0146] In one embodiment, if the second temperature difference between the exhaust temperature and the inlet water temperature exceeds a second preset difference range, it is determined whether the outlet water temperature is less than the target outlet water temperature and whether the error between the outlet water temperature and the target outlet water temperature is greater than a preset error value; if so, the operating frequency of the compressor is increased, and / or the valve opening of the expansion valve is decreased; if not, the operating frequency of the compressor is decreased, and / or the valve opening of the expansion valve is increased.

[0147] Optionally, during actual operation, carbon dioxide heat pump systems may encounter three common phenomena requiring adjustment: excessively low outlet water temperature, excessively high outlet water temperature, and normal outlet water temperature but low energy efficiency. For these three common phenomena, based on the first temperature difference between the air cooler's inlet air temperature and the outlet water temperature, and the second temperature difference between the air cooler's exhaust temperature and the inlet water temperature, the following are the criteria for determining the phenomena, their causes, and specific control methods:

[0148] 1. Low water temperature: This is manifested as the water temperature being lower than the target water temperature, and the error between the water temperature and the target water temperature being greater than the preset error value (e.g., 5%).

[0149] 1) Insufficient refrigerant circulation: This is manifested by a small second temperature difference T2 (e.g., T2≤3℃). The refrigerant circulation volume of the system can be increased by increasing the compressor's operating frequency, thereby increasing the heat exchange capacity of the air cooler and allowing the outlet water temperature to reach the target outlet water temperature.

[0150] 2) If the first temperature difference T1 is too small (e.g., T1≤21℃), the second temperature difference T2 will be too large (e.g., T2>5℃). The first temperature difference can be increased by reducing the opening of the expansion valve, thereby increasing the heat exchange of the air cooler and allowing the outlet water temperature to reach the target outlet water temperature.

[0151] 2. Excessive water temperature: This is manifested as the water temperature being higher than the target water temperature, and the error between the water temperature and the target water temperature being greater than the preset error value (e.g., 5%).

[0152] 1) Excessive refrigerant circulation: This manifests as a large temperature difference (T2) (e.g., T2 > 5℃). The amount of refrigerant circulating in the system can be reduced by decreasing the compressor's operating frequency, thereby reducing the heat exchange capacity of the air cooler and lowering the outlet water temperature.

[0153] 2) If the first temperature difference T1 is too large (e.g., T1 > 26℃), it will manifest as a large second temperature difference T2 (e.g., T2 > 5℃). The first temperature difference can be reduced by increasing the opening of the expansion valve, thereby reducing the heat exchange of the air cooler and decreasing the outlet water temperature.

[0154] 3. Low energy efficiency: This is manifested when the error between the outlet water temperature and the target outlet water temperature is less than or equal to the preset error value (e.g., 5%).

[0155] 1) Excessive refrigerant circulation: This manifests as a large second temperature difference T2 (e.g., T2 > 5℃). The amount of refrigerant circulating in the system can be reduced by decreasing the compressor's operating frequency. This extends the time for a unit mass of refrigerant to exchange heat with water in the air cooler, thus improving the air cooler's heat exchange efficiency.

[0156] 2) If the first temperature difference T1 is too large (e.g., T1 > 26℃), it will manifest as a large second temperature difference T2 (e.g., T2 > 5℃). The first temperature difference can be reduced by increasing the opening of the expansion valve, thereby extending the time for heat exchange between the refrigerant and water per unit mass in the air cooler and improving the heat exchange efficiency of the air cooler.

[0157] As described above, when the three adjustable phenomena occur—low outlet water temperature, high outlet water temperature, and normal outlet water temperature but low energy efficiency—the second temperature difference T2 will exceed the second preset difference range (T2≤3℃ or T2>5℃). Therefore, this embodiment monitors the second temperature difference and controls the compressor and expansion valve when the second temperature difference exceeds the second preset difference range to ensure that the carbon dioxide heat pump system has a high energy efficiency ratio while achieving the target heating capacity.

[0158] Understandably, if the second temperature difference T2 exceeds the second preset difference range (T2≤3℃ or T2>5℃), and the outlet water temperature is lower than the target outlet water temperature, and the error between the outlet water temperature and the target outlet water temperature is greater than the preset error value (5%), then according to point 1 in the above phenomenon description, the operating frequency of the compressor is increased and / or the valve opening of the expansion valve is reduced, thereby increasing the heat exchange of the air cooler and making the outlet water temperature reach the target outlet water temperature.

[0159] If the second temperature difference T2 exceeds the second preset difference range (T2≤3℃ or T2>5℃), and the outlet water temperature is greater than or equal to the target outlet water temperature, or the error between the outlet water temperature and the target outlet water temperature is less than or equal to the preset error value (5%), then according to points 2 and 3 in the above phenomenon description, the compressor's operating frequency is reduced and / or the expansion valve's opening is increased. This reduces the heat exchange capacity of the air cooler, lowering the outlet water temperature; or it prolongs the time for a unit mass of refrigerant to exchange heat with water in the air cooler, improving the air cooler's heat exchange efficiency.

[0160] In this embodiment, the carbon dioxide heat pump system is controlled by monitoring a second temperature difference between the exhaust temperature of the air cooler and the inlet water temperature. If the second temperature difference exceeds a second preset range, the outlet water temperature is lower than the target outlet water temperature, and the error between the outlet water temperature and the target outlet water temperature is greater than a preset error value, the compressor's operating frequency is increased, and / or the expansion valve opening is decreased. If the second temperature difference exceeds a second preset range, the outlet water temperature is greater than or equal to the target outlet water temperature, or the error between the outlet water temperature and the target outlet water temperature is less than or equal to a preset error value, the compressor's operating frequency is decreased, and / or the expansion valve opening is increased. The entire control process ensures that the outlet water temperature reaches the target outlet water temperature while maintaining a high energy efficiency ratio for the carbon dioxide heat pump system.

[0161] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0162] Based on the inventive concept of the control method for the aforementioned carbon dioxide heat pump system, such as Figure 7 As shown in the illustration, this application also provides a control device 700 for a carbon dioxide heat pump system used to implement the control method of the carbon dioxide heat pump system described above. The carbon dioxide heat pump system includes a carbon dioxide circulation loop and a hot water production loop. The carbon dioxide circulation loop includes a compressor and an air cooler. The first air inlet of the air cooler is connected to the exhaust port of the compressor, and the first water outlet of the air cooler is connected to the outlet of the hot water production loop. Temperature sensors are installed at both the first air inlet and the first water outlet to detect the inlet air temperature and the outlet water temperature, respectively. The control device 700 for the carbon dioxide heat pump system includes:

[0163] The range determination module 701 is used to determine a first preset difference range between the air inlet temperature and the water outlet temperature based on the target water outlet temperature.

[0164] The frequency increase control module 702 is used to increase the operating frequency of the compressor when the first temperature difference between the inlet air temperature and the outlet water temperature is less than the lower limit of the first preset difference range, and the first error value between the lower limit of the first preset difference range and the first temperature difference exceeds the first preset error value.

[0165] The frequency reduction control module 703 is used to reduce the operating frequency of the compressor when the first temperature difference is greater than the upper limit of the first preset difference range and the second error value between the first temperature difference and the upper limit of the first preset difference range exceeds the second preset error value.

[0166] In one embodiment, the carbon dioxide circulation loop further includes a regenerator and an expansion valve; the first exhaust port of the air cooler is connected to the high-temperature side inlet of the regenerator, the high-temperature side outlet of the regenerator is connected to the inlet of the expansion valve, and the first water inlet of the air cooler is connected to the water inlet of the hot water circuit; temperature sensors are provided at both the first exhaust port and the first water inlet, respectively, to detect the exhaust temperature of the first exhaust port and the inlet temperature of the first water inlet.

[0167] In one embodiment, the control device 700 of the carbon dioxide heat pump system further includes a valve control module for reducing the valve opening of the expansion valve when the second temperature difference between the exhaust temperature and the inlet water temperature falls within any of the temperature ranges to be adjusted.

[0168] In one embodiment, the frequency increase control module 702 is further configured to, when the first temperature difference is less than the lower limit of the first preset difference range and the first error value exceeds the first preset error value, determine the first frequency adjustment amount of the compressor based on the difference between the outlet water temperature and the inlet water temperature, the first error value and the ambient temperature; and increase the operating frequency of the compressor by the first frequency adjustment amount.

[0169] In one embodiment, the frequency reduction control module 703 is further configured to determine a second frequency adjustment amount of the compressor based on the difference between the outlet water temperature and the inlet water temperature, the second error value, and the ambient temperature when the first temperature difference is greater than the upper limit of the first preset difference range and the second error value exceeds the second preset error value; and reduce the operating frequency of the compressor by the second frequency adjustment amount.

[0170] In one embodiment, the frequency upsampling control module 702 is further configured to, when the first temperature difference is less than the lower limit of the first preset difference range and the first error value exceeds the first preset error value, control the compressor to run at the current operating frequency for a first preset time, and then determine whether the first temperature difference is less than the lower limit of the first preset difference range and whether the first error value exceeds the first preset error value; if so, determine the first frequency adjustment amount of the compressor based on the difference between the outlet water temperature and the inlet water temperature, the first error value, and the ambient temperature.

[0171] In one embodiment, the frequency reduction control module 703 is further configured to, when the first temperature difference is greater than the upper limit of the first preset difference range and the second error value exceeds the second preset error value, control the compressor to run at the current operating frequency for a second preset time, and then determine whether the first temperature difference is greater than the upper limit of the first preset difference range and whether the second error value exceeds the second preset error value; if so, determine the second frequency adjustment amount of the compressor based on the difference between the outlet water temperature and the inlet water temperature, the second error value and the ambient temperature.

[0172] In one embodiment, the valve control module is further configured to determine the valve opening adjustment amount corresponding to any one adjustable temperature range when the second temperature difference belongs to any one adjustable temperature range; different adjustable temperature ranges correspond to different valve opening adjustment amounts; and reduce the valve opening of the expansion valve by the valve opening adjustment amount.

[0173] In one embodiment, the valve control module is further configured to, when the second temperature difference belongs to any temperature range to be adjusted, control the expansion valve to maintain the current valve opening for a third preset time, and then determine whether the second temperature difference belongs to any temperature range to be adjusted; if so, determine the valve opening adjustment amount corresponding to any temperature range to be adjusted.

[0174] In one embodiment, the control device 700 of the carbon dioxide heat pump system further includes a second temperature difference control module, used to determine whether the outlet water temperature is lower than the target outlet water temperature and whether the error value between the outlet water temperature and the target outlet water temperature is greater than a preset error value when the second temperature difference between the exhaust temperature and the inlet water temperature exceeds a second preset difference range; if so, increase the operating frequency of the compressor and / or decrease the valve opening of the expansion valve; if not, decrease the operating frequency of the compressor and / or increase the valve opening of the expansion valve.

[0175] This application also provides an electronic device, which can be a terminal, and its internal structure diagram can be as follows: Figure 8 As shown, the electronic device includes a processor, memory, input / output interface, communication interface, display unit, and input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The input / output interface is used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When the computer program is executed by the processor, it implements a control method for a carbon dioxide heat pump system. The display unit is used to form a visually visible image and can be a display screen, projection device, or virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the electronic device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the casing of the electronic device, or external keyboards, touchpads, or mice, etc.

[0176] Those skilled in the art will understand that Figure 8The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0177] In one embodiment, an electronic device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0178] Based on the target outlet water temperature, determine the first preset difference range between the inlet air temperature and the outlet water temperature;

[0179] If the first temperature difference between the inlet air temperature and the outlet water temperature is less than the lower limit of the first preset difference range, and the first error value between the lower limit of the first preset difference range and the first temperature difference exceeds the first preset error value, the operating frequency of the compressor is increased.

[0180] If the first temperature difference is greater than the upper limit of the first preset difference range, and the second error value between the first temperature difference and the upper limit of the first preset difference range exceeds the second preset error value, the operating frequency of the compressor is reduced.

[0181] In one embodiment, the processor, when executing the computer program, further performs the following steps: reducing the valve opening of the expansion valve when the second temperature difference between the exhaust temperature and the inlet water temperature falls within any temperature range to be adjusted.

[0182] In one embodiment, when the processor executes the computer program, it further performs the following steps: when the first temperature difference is less than the lower limit of the first preset difference range and the first error value exceeds the first preset error value, the processor determines the first frequency adjustment amount of the compressor based on the difference between the outlet water temperature and the inlet water temperature, the first error value and the ambient temperature; and increases the operating frequency of the compressor by the first frequency adjustment amount.

[0183] In one embodiment, when the processor executes the computer program, it further performs the following steps: when the first temperature difference is greater than the upper limit of the first preset difference range and the second error value exceeds the second preset error value, a second frequency adjustment amount of the compressor is determined based on the difference between the outlet water temperature and the inlet water temperature, the second error value and the ambient temperature; and the operating frequency of the compressor is reduced by the second frequency adjustment amount.

[0184] In one embodiment, when the processor executes the computer program, it further performs the following steps: when the first temperature difference is less than the lower limit of the first preset difference range and the first error value exceeds the first preset error value, after controlling the compressor to run at the current operating frequency for a first preset time, it determines whether the first temperature difference is less than the lower limit of the first preset difference range and whether the first error value exceeds the first preset error value; if so, it determines the first frequency adjustment amount of the compressor based on the difference between the outlet water temperature and the inlet water temperature, the first error value, and the ambient temperature.

[0185] In one embodiment, when the processor executes the computer program, it further performs the following steps: when the first temperature difference is greater than the upper limit of the first preset difference range and the second error value exceeds the second preset error value, after controlling the compressor to run at the current operating frequency for a second preset time, it determines whether the first temperature difference is greater than the upper limit of the first preset difference range and whether the second error value exceeds the second preset error value; if so, it determines the second frequency adjustment amount of the compressor based on the difference between the outlet water temperature and the inlet water temperature, the second error value, and the ambient temperature.

[0186] In one embodiment, when the processor executes the computer program, it further performs the following steps: when the second temperature difference value belongs to any temperature range to be adjusted, determine the valve opening adjustment amount corresponding to any temperature range to be adjusted; different temperature ranges to be adjusted correspond to different valve opening adjustment amounts; reduce the valve opening of the expansion valve by the valve opening adjustment amount.

[0187] In one embodiment, when the processor executes the computer program, it further implements the following steps: if the second temperature difference belongs to any temperature range to be adjusted, after controlling the expansion valve to maintain the current valve opening for a third preset time, it determines whether the second temperature difference belongs to any temperature range to be adjusted; if so, it determines the valve opening adjustment amount corresponding to any temperature range to be adjusted.

[0188] In one embodiment, when the processor executes the computer program, it further performs the following steps: if the second temperature difference between the exhaust temperature and the inlet water temperature exceeds a second preset difference range, it determines whether the outlet water temperature is less than the target outlet water temperature and whether the error value between the outlet water temperature and the target outlet water temperature is greater than a preset error value; if yes, it increases the operating frequency of the compressor and / or decreases the valve opening of the expansion valve; if no, it decreases the operating frequency of the compressor and / or increases the valve opening of the expansion valve.

[0189] This application also provides a computer storage medium storing instructions that, when run on a computer or processor, cause the computer or processor to perform one or more steps in the above embodiments. If the constituent modules of the above-described electronic device are implemented as software functional units and sold or used as independent products, they can be stored in the above-described computer-readable storage medium.

[0190] In one embodiment, a computer storage medium is provided having a computer program stored thereon, which, when executed by a processor, performs the following steps:

[0191] Based on the target outlet water temperature, determine the first preset difference range between the inlet air temperature and the outlet water temperature;

[0192] If the first temperature difference between the inlet air temperature and the outlet water temperature is less than the lower limit of the first preset difference range, and the first error value between the lower limit of the first preset difference range and the first temperature difference exceeds the first preset error value, the operating frequency of the compressor is increased.

[0193] If the first temperature difference is greater than the upper limit of the first preset difference range, and the second error value between the first temperature difference and the upper limit of the first preset difference range exceeds the second preset error value, the operating frequency of the compressor is reduced.

[0194] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: reducing the valve opening of the expansion valve when the second temperature difference between the exhaust temperature and the inlet water temperature falls within any temperature range to be adjusted.

[0195] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: when the first temperature difference is less than the lower limit of the first preset difference range and the first error value exceeds the first preset error value, determining a first frequency adjustment amount of the compressor based on the difference between the outlet water temperature and the inlet water temperature, the first error value and the ambient temperature; and increasing the operating frequency of the compressor by the first frequency adjustment amount.

[0196] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: when the first temperature difference is greater than the upper limit of the first preset difference range and the second error value exceeds the second preset error value, a second frequency adjustment amount of the compressor is determined based on the difference between the outlet water temperature and the inlet water temperature, the second error value and the ambient temperature; and the operating frequency of the compressor is reduced by the second frequency adjustment amount.

[0197] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: when the first temperature difference is less than the lower limit of the first preset difference range and the first error value exceeds the first preset error value, after controlling the compressor to run at the current operating frequency for a first preset time, it determines whether the first temperature difference is less than the lower limit of the first preset difference range and whether the first error value exceeds the first preset error value; if so, it determines the first frequency adjustment amount of the compressor based on the difference between the outlet water temperature and the inlet water temperature, the first error value, and the ambient temperature.

[0198] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: when the first temperature difference is greater than the upper limit of the first preset difference range and the second error value exceeds the second preset error value, after controlling the compressor to run at the current operating frequency for a second preset time, it determines whether the first temperature difference is greater than the upper limit of the first preset difference range and whether the second error value exceeds the second preset error value; if so, it determines the second frequency adjustment amount of the compressor based on the difference between the outlet water temperature and the inlet water temperature, the second error value, and the ambient temperature.

[0199] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: when the second temperature difference value belongs to any temperature range to be adjusted, determine the valve opening adjustment amount corresponding to any temperature range to be adjusted; different temperature ranges to be adjusted correspond to different valve opening adjustment amounts; reduce the valve opening of the expansion valve by the valve opening adjustment amount.

[0200] In one embodiment, when the computer program is executed by the processor, it further implements the following steps: if the second temperature difference belongs to any temperature range to be adjusted, after controlling the expansion valve to maintain the current valve opening for a third preset time, it determines whether the second temperature difference belongs to any temperature range to be adjusted; if so, it determines the valve opening adjustment amount corresponding to any temperature range to be adjusted.

[0201] In one embodiment, when the computer program is executed by the processor, it further implements the following steps: if the second temperature difference between the exhaust temperature and the inlet water temperature exceeds a second preset difference range, it determines whether the outlet water temperature is less than the target outlet water temperature and whether the error value between the outlet water temperature and the target outlet water temperature is greater than a preset error value; if yes, it increases the operating frequency of the compressor and / or decreases the valve opening of the expansion valve; if no, it decreases the operating frequency of the compressor and / or increases the valve opening of the expansion valve.

[0202] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer storage medium or transmitted through the computer storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., digital versatile discs (DVDs)), or semiconductor media (e.g., solid-state drives (SSDs)).

[0203] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. This program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above. The aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks. Unless otherwise specified, the technical features of this embodiment and its implementation can be combined arbitrarily.

[0204] The embodiments described above are merely preferred embodiments of this application and are not intended to limit the scope of this application. Any modifications and improvements made by those skilled in the art to the technical solutions of this application without departing from the spirit of this application should fall within the protection scope defined by the claims.

[0205] The foregoing has described specific embodiments of this application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired results. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

Claims

1. A control method for a carbon dioxide heat pump system, characterized in that, The carbon dioxide heat pump system includes a carbon dioxide circulation loop and a hot water production circuit. The carbon dioxide circulation loop includes a compressor and an air cooler. The first air inlet of the air cooler is connected to the exhaust port of the compressor, and the first water outlet of the air cooler is connected to the outlet of the hot water production circuit. Temperature sensors are installed at both the first air inlet and the first water outlet to detect the inlet air temperature and the outlet water temperature, respectively. The method includes: Based on the target outlet water temperature, a first preset difference range between the inlet air temperature and the outlet water temperature is determined; If the first temperature difference between the inlet air temperature and the outlet water temperature is less than the lower limit of the first preset difference range, and the first error between the lower limit of the first preset difference range and the first temperature difference exceeds the first preset error value, the operating frequency of the compressor is increased. If the first temperature difference is greater than the upper limit of the first preset difference range, and the second error value between the first temperature difference and the upper limit of the first preset difference range exceeds the second preset error value, the operating frequency of the compressor shall be reduced.

2. The method as described in claim 1, characterized in that, The carbon dioxide circulation loop also includes a regenerator and an expansion valve; the first exhaust port of the air cooler is connected to the high-temperature side inlet of the regenerator, the high-temperature side outlet of the regenerator is connected to the inlet of the expansion valve, and the first water inlet of the air cooler is connected to the water inlet of the hot water circuit; temperature sensors are provided at both the first exhaust port and the first water inlet to detect the exhaust temperature of the first exhaust port and the inlet temperature of the first water inlet, respectively.

3. The method as described in claim 2, characterized in that, The method further includes: If the second temperature difference between the exhaust temperature and the inlet water temperature falls within any of the temperature ranges to be adjusted, reduce the valve opening of the expansion valve.

4. The method as described in claim 2, characterized in that, When the first temperature difference between the inlet air temperature and the outlet water temperature is less than the lower limit of the first preset difference range, and the first error value between the lower limit of the first preset difference range and the first temperature difference exceeds the first preset error value, increasing the operating frequency of the compressor includes: When the first temperature difference is less than the lower limit of the first preset difference range and the first error value exceeds the first preset error value, the first frequency adjustment amount of the compressor is determined based on the difference between the outlet water temperature and the inlet water temperature, the first error value, and the ambient temperature. The operating frequency of the compressor is increased by the first frequency adjustment amount.

5. The method as described in claim 2, characterized in that, The step of reducing the operating frequency of the compressor when the first temperature difference is greater than the upper limit of the first preset difference range and the second error value between the first temperature difference and the upper limit of the first preset difference range exceeds the second preset error value includes: When the first temperature difference is greater than the upper limit of the first preset difference range and the second error value exceeds the second preset error value, the second frequency adjustment amount of the compressor is determined based on the difference between the outlet water temperature and the inlet water temperature, the second error value, and the ambient temperature. The operating frequency of the compressor is reduced by the second frequency adjustment amount.

6. The method as described in claim 4, characterized in that, When the first temperature difference is less than the lower limit of the first preset difference range and the first error value exceeds the first preset error value, determining the first frequency adjustment amount of the compressor based on the difference between the outlet water temperature and the inlet water temperature, the first error value, and the ambient temperature includes: If the first temperature difference is less than the lower limit of the first preset difference range and the first error value exceeds the first preset error value, the compressor is controlled to run at the current working frequency for a first preset time, and then it is determined whether the first temperature difference is less than the lower limit of the first preset difference range and whether the first error value exceeds the first preset error value. If so, the first frequency adjustment amount of the compressor is determined based on the difference between the outlet water temperature and the inlet water temperature, the first error value, and the ambient temperature.

7. The method as described in claim 5, characterized in that, When the first temperature difference is greater than the upper limit of the first preset difference range and the second error value exceeds the second preset error value, determining the second frequency adjustment amount of the compressor based on the difference between the outlet water temperature and the inlet water temperature, the second error value, and the ambient temperature includes: If the first temperature difference is greater than the upper limit of the first preset difference range and the second error value exceeds the second preset error value, the compressor is controlled to run at the current working frequency for a second preset time, and then it is determined whether the first temperature difference is greater than the upper limit of the first preset difference range and whether the second error value exceeds the second preset error value. If so, the second frequency adjustment amount of the compressor is determined based on the difference between the outlet water temperature and the inlet water temperature, the second error value, and the ambient temperature.

8. The method as described in claim 3, characterized in that, When the second temperature difference between the exhaust temperature and the inlet water temperature falls within any of the temperature ranges to be adjusted, reducing the valve opening of the expansion valve includes: If the second temperature difference falls within any of the adjustable temperature ranges, determine the valve opening adjustment amount corresponding to the adjustable temperature range; different adjustable temperature ranges correspond to different valve opening adjustment amounts. The valve opening of the expansion valve is reduced by the valve opening adjustment amount.

9. The method as described in claim 8, characterized in that, When the second temperature difference value belongs to any one of the adjustable temperature ranges, determining the valve opening adjustment amount corresponding to the adjustable temperature range includes: If the second temperature difference belongs to any of the temperature ranges to be adjusted, the expansion valve is controlled to maintain the current valve opening for a third preset time, and then it is determined whether the second temperature difference belongs to any of the temperature ranges to be adjusted. If so, then determine the valve opening adjustment amount corresponding to any one of the temperature ranges to be adjusted.

10. The method as described in claim 2, characterized in that, The method further includes: If the second temperature difference between the exhaust temperature and the inlet water temperature exceeds a second preset difference range, determine whether the outlet water temperature is less than the target outlet water temperature and whether the error between the outlet water temperature and the target outlet water temperature is greater than a preset error value. If so, increase the operating frequency of the compressor and / or decrease the valve opening of the expansion valve; If not, reduce the operating frequency of the compressor and / or increase the valve opening of the expansion valve.

11. A control device for a carbon dioxide heat pump system, characterized in that, The carbon dioxide heat pump system includes a carbon dioxide circulation loop and a hot water production circuit. The carbon dioxide circulation loop includes a compressor and an air cooler. The first air inlet of the air cooler is connected to the exhaust port of the compressor, and the first water outlet of the air cooler is connected to the outlet of the hot water production circuit. Temperature sensors are installed at both the first air inlet and the first water outlet to detect the inlet air temperature and the outlet water temperature, respectively. The device includes: The range determination module is used to determine a first preset difference range between the air inlet temperature and the water outlet temperature based on the target water outlet temperature. The frequency increase control module is used to increase the operating frequency of the compressor when the first temperature difference between the inlet air temperature and the outlet water temperature is less than the lower limit of the first preset difference range, and the first error value between the lower limit of the first preset difference range and the first temperature difference exceeds the first preset error value. The frequency reduction control module is used to reduce the operating frequency of the compressor when the first temperature difference is greater than the upper limit of the first preset difference range and the second error value between the first temperature difference and the upper limit of the first preset difference range exceeds the second preset error value.

12. An electronic device, characterized in that, include: A processor and a memory; the memory stores a computer program, and the processor executes the computer program to implement the method steps of any one of claims 1-10.

13. A computer storage medium, characterized in that, The computer storage medium stores a plurality of instructions adapted for loading by a processor and executing the method steps as claimed in any one of claims 1-10.

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