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

Abstract

The invention discloses a control method and device of a carbon dioxide heat pump system, electronic equipment and a computer storage medium. The control method and device are applied to the carbon dioxide heat pump system comprising a carbon dioxide circulation loop and a heating water way. The method comprises the steps that a first preset difference value range between the air inlet temperature and the water outlet temperature is determined according to the target water outlet temperature; when a first temperature difference value between the air inlet temperature and the water outlet temperature is smaller than the lower limit of a first preset difference value range, and a first error value between the lower limit of the first preset difference value range and the first temperature difference value exceeds a first preset error value, the working frequency of the compressor is increased; and when the first temperature difference value is larger than the upper limit of the first preset difference value range and a second error value between the first temperature difference value and the upper limit of the first preset difference value range exceeds a second preset error value, the working frequency of the compressor is reduced. According to the control process, it can be guaranteed that the outlet water temperature reaches the target outlet water temperature, and the system has the high energy efficiency ratio.

Description

Technical Field

[0001] The present application relates to the field of heat pump manufacturing, and in particular to a control method, device, electronic equipment and computer storage medium for a carbon dioxide heat pump system. Background Art

[0002] The 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 a low-temperature environment and releasing heat after the temperature is raised to a higher level. For example, a carbon dioxide heat pump water heater uses carbon dioxide to absorb heat from low-temperature air, compress it to a higher temperature, and then release heat to achieve water heating.

[0003] Since the CO2 heat pump system uses the changes of CO2 in the supercritical state to achieve heat transfer, it cannot be controlled based on the exhaust superheat and the subcooling of the liquid refrigerant, that is, the control method of the traditional heat pump system is no longer applicable to the CO2 heat pump system. The existing control method of the CO2 heat pump system cannot achieve a high energy efficiency ratio (Coefficient of Performance, COP) while ensuring the heating capacity of the system. Summary of the invention

[0004] The embodiment of the present application provides a control method, device, electronic device and computer storage medium of a carbon dioxide heat pump system, which can ensure the heating capacity of the carbon dioxide heat pump system while enabling the carbon dioxide heat pump system to have a higher energy efficiency ratio. The above technical solution is as follows:

[0005] In a first aspect, an embodiment of the present application provides a control method for a carbon dioxide heat pump system, wherein the carbon dioxide heat pump system includes a carbon dioxide circulation loop and a hot water circuit, wherein the carbon dioxide circulation loop includes a compressor and an air cooler; a first air inlet of the air cooler is connected to an exhaust port of the compressor, and a first water outlet of the air cooler is connected to a water outlet of the hot water circuit; temperature sensors are provided at the first air inlet and the first water outlet, respectively for detecting an air intake temperature of the first air inlet and a water outlet temperature of the first water outlet; the method includes:

[0006] Determining a first preset difference range between the intake air temperature and the outlet water temperature according to the target outlet water temperature;

[0007] In the case where a first temperature difference between the intake air temperature and the outlet water temperature is less than a lower limit of a first preset difference range, and a first error value between the lower limit of the first preset difference range and the first temperature difference exceeds a first preset error value, increasing the operating frequency of the compressor;

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

[0009] In a 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 provided at the first exhaust port and the first water inlet, which are respectively used to detect the exhaust temperature of the first exhaust port and the water inlet temperature of the first water inlet.

[0010] In a possible implementation, the control method of the carbon dioxide heat pump system further includes: when the second temperature difference between the exhaust temperature and the inlet water temperature belongs to any temperature interval to be adjusted, reducing the valve opening of the expansion valve.

[0011] In one possible implementation, when a first temperature difference between the intake air temperature and the outlet water temperature is less than a lower limit of a first preset difference range, and a first error value between the lower limit of the first preset difference range and the first temperature difference exceeds a first preset error value, the operating frequency of the compressor is increased, including: 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 according to 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.

[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, the operating frequency of the compressor is reduced, including: 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 according to 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 according to the difference between the outlet water temperature and the inlet water temperature, the first error value and the ambient temperature, including: 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, 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 according to 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 according to the difference between the outlet water temperature and the inlet water temperature, the second error value and the ambient temperature, including: 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, 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 according to the difference between the outlet water temperature and the inlet water temperature, the second error value and the ambient temperature.

[0015] In a possible implementation, when the second temperature difference between the exhaust temperature and the inlet water temperature belongs to any temperature interval to be adjusted, the valve opening of the expansion valve is reduced, including: when the second temperature difference belongs to any temperature interval to be adjusted, determining the valve opening adjustment amount corresponding to any temperature interval to be adjusted; different temperature intervals to be adjusted 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 interval to be adjusted, the valve opening adjustment amount corresponding to any temperature interval to be adjusted is determined, including: when the second temperature difference belongs to any temperature interval to be adjusted, controlling the expansion valve to maintain the current valve opening for a third preset time, and then judging whether the second temperature difference belongs to any temperature interval to be adjusted; if so, determining the valve opening adjustment amount corresponding to any temperature interval to be adjusted.

[0017] In a possible implementation, the control method of the above-mentioned carbon dioxide heat pump system also includes: when a second temperature difference between the exhaust temperature and the water inlet temperature exceeds a second preset difference range, judging 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; if so, increasing the operating frequency of the compressor, and / or reducing the valve opening of the expansion valve; if not, reducing the operating frequency of the compressor, and / or increasing the valve opening of the expansion valve.

[0018] In a second aspect, an embodiment of the present application provides a control device for a carbon dioxide heat pump system, wherein the carbon dioxide heat pump system includes a carbon dioxide circulation loop and a hot water circuit, wherein the carbon dioxide circulation loop includes a compressor and an air cooler; a first air inlet of the air cooler is connected to an exhaust port of the compressor, and a first water outlet of the air cooler is connected to a water outlet of the hot water circuit; temperature sensors are provided at the first air inlet and the first water outlet, respectively for detecting an air intake temperature of the first air inlet and a water outlet temperature of the first water outlet; the device includes:

[0019] A range determination module, configured to determine a first preset difference range between the intake air temperature and the outlet water temperature according to the target outlet water temperature;

[0020] A frequency increase control module, configured to increase the operating frequency of the compressor when a first temperature difference between the intake air temperature and the outlet water temperature is less than a lower limit of a first preset difference range, and a first error value between the lower limit of the first preset difference range and the first temperature difference exceeds a 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] In a third aspect, an embodiment of the present application provides an electronic device, comprising: a processor and a memory; wherein the memory stores a computer program, and the computer program is suitable for being loaded by the processor and executing the method steps provided in the first aspect of the embodiment of the present application.

[0023] In a fourth aspect, an embodiment of the present application provides a computer storage medium, wherein the computer storage medium stores a plurality of instructions, and the instructions are suitable for being loaded by a processor and executing the method steps provided in the first aspect of the embodiment of the present application.

[0024] The control method, device, electronic device and computer storage medium of the 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, wherein 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 water outlet of the hot water circuit; temperature sensors are provided at the first air inlet and the first water outlet, respectively for detecting the intake air temperature of the first air inlet and the water outlet temperature of the first water outlet. In the process of controlling the carbon dioxide heat pump system, the ideal first preset difference range between the intake air temperature and the water outlet temperature is determined according to the target water outlet temperature. When the first temperature difference between the intake air temperature and the water outlet 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 amount of the system is increased by increasing the operating frequency of the compressor, thereby enhancing the heat exchange capacity of the air cooler and ensuring that the water outlet temperature of the first water outlet reaches the target water 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 refrigerant circulation volume of the system is reduced by reducing the operating frequency of the compressor, thereby avoiding the problem of insufficient heat exchange in the air cooler and making the carbon dioxide heat pump system have a higher energy efficiency ratio. The control process of the entire carbon dioxide heat pump system uses the first temperature difference between the inlet temperature and the outlet water temperature as a 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 can have a higher energy efficiency ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

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

[0028] Figure 3 A flow chart of a control method of a carbon dioxide heat pump system provided by an exemplary embodiment of the present application;

[0029] Figure 4 A flow chart of another control method of a carbon dioxide heat pump system provided as an exemplary embodiment of the present application;

[0030] Figure 5 A flow chart of another control method of a carbon dioxide heat pump system provided as an exemplary embodiment of the present application;

[0031] Figure 6 A schematic diagram of valve opening control of an expansion valve provided by an exemplary embodiment of the present application;

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

[0033] Figure 8 A schematic structural diagram of an electronic device provided as an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0035] In the description of the present application, it should be understood that the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances. In addition, in the description of the present application, unless otherwise specified, "multiple" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects associated before and after are in an "or" relationship.

[0036] See also Figure 1 First, an application scenario applicable to the embodiment of the present application is introduced: a carbon dioxide heat pump system 10 applied to a high-temperature water heater includes a carbon dioxide circulation loop 11, a hot water circuit 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 circuit 13 is used for the circulation of water. An evaporator 1, a regenerator 2, a compressor 3, an air cooler 4 and an expansion valve 5 are provided on the carbon dioxide circulation loop 11, a bypass valve 6 and a capillary 7 are provided on the bypass branch 13, and the hot water circuit 12 has a water inlet 8 and a water outlet 9.

[0037] The carbon dioxide outlet of the evaporator 1 is connected to the regenerator 2, the compressor 3, and the air cooler 4 in sequence through a pipeline, and then connected to the expansion valve 5 through the regenerator 2, and the expansion valve 5 is connected back to the carbon dioxide inlet of the evaporator 1 through a pipeline, so as to form a carbon dioxide circulation loop 11. That is, the carbon dioxide outlet of the evaporator 1 is connected to the low-temperature side inlet of the regenerator 2 through a pipeline, the low-temperature side outlet of the regenerator 2 is connected to the return air port of the compressor 3 through a pipeline, the exhaust port of the compressor 3 is connected to the first air inlet 41 of the air cooler 4 through a pipeline, the first exhaust port 42 of the air cooler 4 is connected to the high-temperature side inlet of the regenerator 2 through a pipeline, the high-temperature side outlet of the regenerator 2 is connected to the inlet of the expansion valve 5 through a pipeline, and then the outlet of the expansion valve 5 is connected back to the carbon dioxide inlet of the evaporator 1. The bypass branch 13 formed by the bypass valve 6 and the capillary tube 7 in series is connected to the carbon dioxide circulation loop 11, and one end of the bypass branch 13 is connected to the exhaust port of the compressor 3 through a pipeline, and the other end is connected to the carbon dioxide inlet of the evaporator 5 through a pipeline.

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

[0039] The working process of the carbon dioxide heat pump system 10 is as follows: after the carbon dioxide working medium absorbs heat in the evaporator 1 and becomes low-temperature carbon dioxide steam, it enters the low-temperature side inlet of the regenerator 2, and performs heat exchange with the high-temperature carbon dioxide steam returned from the air cooler 4 in the regenerator 2 to form preheated carbon dioxide steam. The preheated carbon dioxide steam enters the return air port of the compressor 3 from the low-temperature side outlet of the regenerator 2, and is compressed into high-temperature and high-pressure carbon dioxide steam in the compressor 3. The high-temperature and high-pressure carbon dioxide steam flows out from the exhaust port of the compressor 3 and enters the first air inlet 41 of the air cooler 4, where it releases a large amount of heat to heat the water entering from the first water inlet 43. The heated water flows out from the first water outlet 44, and the cooled high-temperature and high-pressure carbon dioxide steam returns to the regenerator 2 from the high-temperature side inlet of the regenerator 2 to be reheated, and then flows out from the high-temperature side outlet of the regenerator 2 and returns to the evaporator 1 through the expansion valve 5, thereby completing a cycle. In the defrosting mode, the bypass valve 6 is opened, so that part of the high-temperature gas passing through the compressor 3 enters the evaporator 1 for defrosting after the flow rate and pressure are adjusted by the 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 intake 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.

[0041] It is worth noting that this embodiment only describes a preferred application scenario of the present application. The present application does not impose any restrictions on the specific structure, setting position and setting quantity of each component in the carbon dioxide heat pump system 10 (including but not limited to the evaporator 1, the regenerator 2, the compressor 3, the air cooler 4, the expansion valve 5, the temperature sensor, etc.), and technicians in this field can set them according to actual conditions.

[0042] The control method of the carbon dioxide heat pump system provided in the embodiment of the present application can be applied to 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 the system can have a higher energy efficiency ratio. Specifically, the controller 20 determines the first preset difference range between the intake air temperature and the outlet water temperature according to the target outlet water temperature; when the first temperature difference between the intake 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 3 is increased; 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 operating frequency of the compressor 3 is reduced. Among them, the controller 20 can at least obtain the detection result 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 according to the detection result uploaded by the temperature sensor, which is not limited in this application. It is understandable 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 the present 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, Figure 3 As shown, a control method for a carbon dioxide heat pump system is provided. Figure 2 As an example, the controller 20 in FIG. Figure 1 The carbon dioxide heat pump system 10 shown is illustrated and includes the following steps:

[0044] S301: Determine a first preset difference range between the intake air temperature and the outlet water temperature according to the target outlet water temperature.

[0045] Among them, the inlet air temperature is the temperature detected in real time by the 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 the temperature sensor at the first outlet water 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. The difference between the inlet water temperature and the outlet water temperature is kept within the first preset difference range, which can make the outlet water temperature of the first outlet water 44 reach the target outlet water temperature, and the carbon dioxide heat pump system 10 has a higher energy efficiency ratio. The corresponding relationship 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 water outlet temperature

[0047]

[0048] It can be seen from Table 1 that when the target outlet water temperature is between 55°C-70°C, the first preset difference range between the intake air temperature and the outlet water temperature is 22°C-25°C; when the target outlet water temperature is between 70°C-90°C, the first preset difference range between the intake air temperature and the outlet water temperature is 25°C-30°C.

[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 to between 50°C and 60°C, the controller 20 determines that the first preset difference range between the intake 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 to between 75°C and 85°C, the controller 20 determines that the first preset difference range between the intake air temperature and the outlet water temperature is 26°C to 30°C.

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

[0051] The first preset error value is a preset error threshold, for example, it can be set to 1°C, and can also be adjusted according to actual needs, for example, it can be set to 2°C, 5°C, etc. The smaller the first preset error value is set, the smaller the deviation between the first temperature difference acceptable to the system and the lower limit of the first preset difference range is.

[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 (such as 1°C), the difference between the temperature of 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 of the air cooler 4 is insufficient. At this time, it is necessary to increase the operating frequency of the compressor 3 to speed up the circulation speed of the refrigerant in the carbon dioxide heat pump system 10, so as to ensure that more refrigerant flows through the air cooler 4 per unit time to exchange heat with water, thereby enhancing the heat exchange capacity of the air cooler 4.

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

[0054] The second preset error value is a preset error threshold, and the second preset error value may be the same as or different from the first preset error value. For example, the second preset error value may be set to 1°C, and may also be adjusted according to actual needs, such as setting it to 2°C, 5°C, etc. The smaller the second preset error value is set, the smaller the deviation between the first temperature difference acceptable to the system and the upper limit of the first preset difference range is.

[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, the refrigerant temperature before entering the air cooler 4 is too different from the water temperature after being heated by the air cooler 4, which means that the refrigerant is not fully 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, so as to ensure that the time for the unit mass of refrigerant to exchange heat with 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 above-mentioned carbon dioxide heat pump system, the controller determines the ideal first preset difference range between the intake air temperature and the outlet water temperature according to the target outlet water temperature. When the first temperature difference between the intake 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 refrigerant circulation volume of the system by increasing the operating frequency of the compressor, thereby enhancing the heat exchange capacity of the air cooler and ensuring that the outlet water temperature of the first outlet reaches the target outlet water 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 reduces the refrigerant circulation volume of the system by reducing the operating frequency of the compressor, thereby avoiding the problem of insufficient heat exchange in the air cooler and making the carbon dioxide heat pump system have a higher energy efficiency ratio. The control process of the entire carbon dioxide heat pump system takes the first temperature difference between the inlet temperature and the outlet water temperature as a 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 can have a higher energy efficiency ratio.

[0057] In one embodiment, Figure 4 As shown, another control method for a carbon dioxide heat pump system is provided, and the method is applied to Figure 2 As an example, the controller 20 in FIG. Figure 1 The carbon dioxide heat pump system 10 shown is illustrated and includes the following steps:

[0058] S401: Determine a first preset difference range between the intake air temperature and the outlet water temperature according to the target outlet water temperature.

[0059] Specifically, S401 is consistent with S301 and will not be described in detail here.

[0060] S402: Control the compressor to operate according to the initial frequency.

[0061] Optionally, the initial frequency of the compressor 3 can be calculated by reverse calculation based on the target heating capacity of the carbon dioxide heat pump system 10 in combination with the ambient temperature around the carbon dioxide heat pump system 10. First, the evaporation temperature of the evaporator 14 is determined according to the ambient temperature during the operation of the carbon dioxide heat pump system 10 and the estimated heat exchange temperature difference, and the return air density of the carbon dioxide gas is determined by the evaporation temperature and the state equation of the carbon dioxide gas. Then, the estimated required carbon dioxide flow rate of the carbon dioxide heat pump system 10 is calculated based on the target heating capacity and the estimated specific enthalpy difference of the carbon dioxide gas at the first air inlet 41 and the first exhaust port 42. Finally, the initial frequency of the compressor 3 is calculated based on the estimated required carbon dioxide flow rate, the exhaust volume of the compressor 3, the return air density of the carbon dioxide gas, and the volumetric efficiency of the compressor 3. The carbon dioxide heat pump system can achieve a higher energy efficiency ratio while achieving the target heating capacity when operating at the calculated initial frequency. Assuming that the heat exchange temperature difference is 5°C, the specific calculation formula for the initial frequency of the compressor 3 is as follows:

[0062]

[0063] Among them, T eva is the evaporation temperature of the evaporator 13, T4 is the ambient temperature when the carbon dioxide heat pump system 10 is running, T eva The unit of T and T4 is degrees Celsius (℃). hq is the return air density of carbon dioxide gas, its unit is kilogram per cubic meter (kg / m 3 ), F(T eva ) refers to the determination of the return gas density of carbon dioxide gas by the state equation of carbon dioxide gas. ref Q is the estimated required carbon dioxide flow rate of the carbon dioxide heat pump system 10, in kilograms per second (kg / s); a is the target heating capacity of the carbon dioxide heat pump system 10, in kilowatts (kW); h ref_in is the estimated specific enthalpy of carbon dioxide gas at the first air inlet 41, h ref_out is the estimated specific enthalpy of carbon dioxide gas at the first exhaust port 42, h ref_in and h ref_out The unit is kilojoule per kilogram (KJ / kg). f is the initial operating frequency of compressor 3, and its unit is Hertz (Hz); v is the exhaust volume of compressor 3, and its unit is cubic meter (m 3 );η v is the volumetric efficiency η of compressor 3 v , which is an empirical coefficient of 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, determine the first frequency adjustment amount of the compressor according to the difference between the outlet water temperature and the inlet water temperature, the first error value and the ambient temperature.

[0065] Optionally, 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 (22°C or 26°C) as 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°C), the controller 20 determines the first frequency adjustment amount of the compressor 3 by looking up the table based on the difference between the outlet water temperature of the first water outlet 44 and the inlet water temperature of the first water inlet 43 (inlet and 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 and outlet water temperature difference is between 20°C-30°C, the first frequency adjustment amount is determined by referring to Table 2 in combination with the first error value ΔT1 and the ambient temperature; when the inlet and outlet water temperature difference is between 40°C-60°C, the first frequency adjustment amount is determined by referring to Table 3 in combination with the first error value ΔT1 and the ambient temperature. Table 2-3 is shown below:

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

[0067]

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

[0069]

[0070]

[0071] Exemplarily, assuming that the ambient temperature is 20°C, when the first temperature difference between the inlet temperature and the outlet water temperature is 18°C, the first error value ΔT1=22°C-18°C=4°C∈(3,5) is determined in combination with Table 1. If the difference between the outlet water temperature of the first water outlet 44 and the inlet water temperature of the first water inlet 43 is 25°C at this time, the first frequency adjustment amount is determined to be 0Hz (maintaining the current operating frequency) with reference to Table 2. If the difference between the outlet water temperature of the first water outlet 44 and the inlet water temperature of the first water inlet 43 is 50°C at this time, the first frequency adjustment amount is determined to be 1Hz with reference to Table 3.

[0072] S404: Increase the operating frequency of the compressor by a first frequency adjustment amount.

[0073] It can be understood that the first temperature difference is less than the lower limit of the first preset difference range (22°C or 26°C), and the first error value exceeds the first preset error value (1°C), which means that the difference between the refrigerant temperature 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, to increase the current operating frequency of the compressor 3 by the first frequency adjustment amount (such as 1Hz, etc.), so as to ensure that more refrigerant flows through the air cooler 4 per unit time to exchange heat with water, 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, determine the second frequency adjustment amount of the compressor according to the difference between the outlet water temperature and the inlet water temperature, the second error value and the ambient temperature.

[0075] Optionally, when the first temperature difference between the intake air temperature and the outlet water temperature is greater than the upper limit of the first preset difference range (25°C or 30°C) 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°C), the controller 20 determines the second frequency adjustment amount of the compressor 3 by looking up the table based on the difference between the outlet water temperature of the first water outlet 44 and the inlet water temperature of the first water inlet 43 (inlet and 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 and outlet water temperature difference is between 20°C-30°C, the first frequency adjustment amount is determined with reference to Table 4 in combination with the second error value ΔT1' and the ambient temperature; when the inlet and outlet water temperature difference is between 40°C-60°C, the second frequency adjustment amount is determined with reference 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 and outlet water temperature difference: 20℃-30℃)

[0077]

[0078]

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

[0080]

[0081] Exemplarily, assuming that the ambient temperature is 20°C, when the first temperature difference between the inlet temperature and the outlet water temperature is 30°C, the second error value ΔT1′=30°C-25°C=5°C∈(3°C,5°C) is determined in combination with Table 1. If the difference between the outlet water temperature of the first water outlet 44 and the inlet water temperature of the first water inlet 43 is 25°C at this time, the second frequency adjustment amount is determined to be 0Hz (maintaining the current operating frequency) with reference to Table 4. If the difference between the outlet water temperature of the first water outlet 44 and the inlet water temperature of the first water inlet 43 is 50°C at this time, the second frequency adjustment amount is determined to be 1Hz with reference to Table 5.

[0082] S406: Reduce the operating frequency of the compressor by a second frequency adjustment amount.

[0083] It can be understood that if the first temperature difference is greater than the upper limit of the first preset difference range (25°C or 30°C), and the second error value exceeds the second preset error value (1°C), it means that the temperature of the refrigerant before entering the air cooler 4 is too different from the water temperature after being heated by the air cooler 4, and the refrigerant is not fully 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, to reduce the current operating frequency of the compressor 3 by the second frequency adjustment amount (such as 1Hz, etc.), so as to ensure that the time for the unit mass of refrigerant to exchange heat with water in the air cooler 4 is extended, avoiding the problem of insufficient heat exchange due to excessive refrigerant circulation, thereby improving the energy efficiency ratio of the carbon dioxide heat pump system 10.

[0084] S407: When the second temperature difference between the exhaust gas temperature and the inlet water temperature belongs to any temperature interval to be adjusted, reducing the valve opening of the expansion valve.

[0085] Optionally, when the second temperature difference T2 between the exhaust temperature and the inlet water temperature belongs to any temperature interval to be adjusted as shown in Table 6, that is, when the second temperature difference T2 is greater than or equal to 3°C, the valve opening adjustment amount corresponding to any temperature interval 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 in units of valve steps, and different valve opening adjustment amounts correspond to different temperature intervals 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 one-time opening of the valve changes to 2 steps, that is, the expansion valve 5 is opened at twice the minimum adjustment unit of the valve (such as 5% of the opening size). If the second temperature difference T2 between the exhaust temperature and the inlet water temperature is 8°C, the one-time opening of the valve changes to 5 steps, at this time, the expansion valve 5 is opened at five times the minimum adjustment unit of the valve. If the second temperature difference T2 between the exhaust temperature and the inlet water temperature is 8°C, the one-time opening of the valve changes to 1 step, at this time, the expansion valve 5 is opened at the minimum adjustment unit of the valve.

[0090] In this embodiment, the controller controls the compressor to work according to the initial frequency obtained by reverse calculation from the ambient temperature and the target heating amount of the carbon dioxide heat pump system. During the operation of the carbon dioxide heat pump system, the first temperature difference between the air inlet temperature and the water outlet temperature of the air cooler and the second temperature difference between the exhaust temperature and the water inlet temperature of the air cooler are used as control variables. When the first temperature difference does not belong to the first preset difference range and is greatly different from the first preset difference range, the carbon dioxide heat pump system is controlled by increasing or decreasing the operating frequency of the compressor. When the second temperature difference belongs to the temperature range to be adjusted, the carbon dioxide heat pump system is controlled by reducing the valve opening of the expansion valve. The control process of the entire carbon dioxide heat pump system combines initial frequency control, real-time temperature detection, frequency control regulation and valve control regulation, so that the carbon dioxide heat pump system has a higher energy efficiency ratio while achieving the target heating amount.

[0091] In one embodiment, Figure 5 As shown, another control method for a carbon dioxide heat pump system is provided, and the method is applied to Figure 2 As an example, the controller 20 in FIG. Figure 1 The carbon dioxide heat pump system 10 shown is illustrated and includes the following steps:

[0092] S501: Determine a first preset difference range between the intake air temperature and the outlet water temperature according to the target outlet water temperature.

[0093] Specifically, S501 is consistent with S301 and will not be described in detail here.

[0094] S502: Control the compressor to operate according to the initial frequency.

[0095] Specifically, S502 is consistent with S402 and will not be described in detail here.

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

[0097] Optionally, in combination with the target outlet water temperature of the carbon dioxide heat pump system 10, it is determined whether the first temperature difference between the air intake temperature of the first air intake port 41 and the outlet water temperature of the first outlet water port 44 exceeds the first preset difference range by referring to Table 1. That is, when the target outlet water temperature of the carbon dioxide heat pump system 10 is between 55°C and 70°C, it is determined whether the first temperature difference exceeds 22°C and 25°C; when the target outlet water temperature of the carbon dioxide heat pump system 10 is between 70°C and 90°C, it is determined whether the first temperature difference exceeds 26°C and 30°C.

[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 not, execute S511.

[0099] Optionally, when the first temperature difference exceeds the 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°C and 70°C, it is determined whether the first temperature difference is less than 22°C; when the target outlet water temperature of the carbon dioxide heat pump system 10 is between 70°C and 90°C, it is determined whether the first temperature difference is less than 26°C.

[0100] S505: Determine whether the first error value exceeds the first preset error value. If yes, execute S506; if no, return to the above S503.

[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° C.).

[0102] S506: Control the compressor to operate at the current operating frequency for a first preset time period.

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

[0104] Optionally, if after the compressor 3 runs at the current operating frequency for 30 seconds, 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, 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, the process of controlling the compressor to run at the current operating frequency for the first preset time period can effectively ensure that the system has reached a stable state before the controller adjusts the frequency of the compressor, avoiding unnecessary frequency adjustments due to 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; if no, return to the above S503.

[0107] Optionally, after the controller 20 controls the compressor 3 to operate at the current operating frequency for 30 seconds, it is determined again whether the first error value exceeds the first preset error value. Only when the first error value exceeds the first preset error value, the first frequency adjustment amount is further determined according to the current first error value to increase 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.

[0108] S508: Determine a first frequency adjustment amount of the compressor according to 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 described in detail here.

[0110] S509: Increase the operating frequency of the compressor by the first frequency adjustment amount.

[0111] For details, please refer to S404, which will not be described in detail here.

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

[0113] Optionally, after the controller 20 controls the compressor 3 to run at the upgraded operating frequency for 30 seconds, it is considered that the system has reached a stable state, and then the process returns to S503 to re-evaluate 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; if no, return to the above S503.

[0115] Optionally, in the case where the first temperature difference exceeds the first preset difference range, if the first temperature difference is not less than the lower limit of the first preset difference range, the first temperature difference is greater than the lower limit of the first preset difference range. At this time, 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 the second preset error value (1°C).

[0116] S512: Control the compressor to operate at the current operating frequency for a second preset time period.

[0117] The second preset time length is a preset stability confirmation time length, which is used to verify whether the compressor 3 still meets the frequency increase condition after running at the current operating frequency for a period of time. The second preset time length can be set to 30 seconds, and can also be adjusted according to actual needs, for example, to 20 seconds, 1 minute, etc. The smaller the second preset time length is set, the faster the controller 20 responds to system changes.

[0118] Optionally, if after the compressor 3 runs at the current operating frequency for 30 seconds, 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, 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, the process of controlling the compressor to run at the current operating frequency for the second preset time period can effectively ensure that the system has reached a stable state before the controller adjusts the frequency of the compressor, avoiding unnecessary frequency adjustments due to 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; if no, return to the above S503.

[0121] Optionally, after the controller 20 controls the compressor 3 to operate at the current operating frequency for 30 seconds, it is determined again whether the second error value exceeds the second preset error value. Only when the second error value exceeds the second preset error value, the second frequency adjustment amount is further determined according to 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 a second frequency adjustment amount of the compressor according to 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 described in detail here.

[0124] S515: Reduce the operating frequency of the compressor by a second frequency adjustment amount.

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

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

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

[0128] S517: Determine whether the second temperature difference belongs to any temperature range to be adjusted. If yes, execute S518; if no, return to the above S503.

[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 water inlet temperature of the first water inlet 43 belongs to any of the temperature intervals to be adjusted. As can be seen from Table 6, as long as the second temperature difference T2 is greater than or equal to 3°C, it must belong to one of the three temperature intervals to be adjusted.

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

[0131] The third preset time is a preset stability confirmation time, which is 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 time can be set to 30 seconds, and can also be adjusted according to actual needs, for example, to 20 seconds, 1 minute, etc. The smaller the third preset time is set, the faster the controller 20 responds to system changes.

[0132] Optionally, if the second temperature difference still belongs to any temperature range to be adjusted after the expansion valve 5 runs at the current operating frequency for 30 seconds, the controller 20 will execute the operation of reducing the valve opening of the expansion valve 5; otherwise, the controller 20 will re-evaluate the conditions to determine whether to maintain the current operating state of the system.

[0133] In this embodiment, the process of controlling the compressor to run at the current operating frequency for the third preset time period can effectively ensure that the system has reached a stable state before the controller adjusts the valve opening of the expansion valve, thereby avoiding unnecessary frequency adjustments due to short-term external interference or system instability, and enhancing the robustness of control and the operating efficiency of the system.

[0134] S519: Determine whether the second temperature difference belongs to any temperature range to be adjusted. If yes, execute S520; if no, return to the above S503.

[0135] Optionally, the controller 20 controls the expansion valve 5 to maintain the current valve opening for 30 seconds, and then determines again whether the second temperature difference belongs to any temperature interval to be adjusted. Only when the second temperature difference still belongs to any temperature interval to be adjusted, the valve opening adjustment amount is further determined according to 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 working 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 interval to be adjusted, wherein the valve opening adjustment amount is in valve steps, and different valve opening adjustment amounts correspond to different temperature intervals to be adjusted.

[0138] It can be seen from Table 6 that when the second temperature difference T2 is greater than or equal to 7°C, the valve opening adjustment amount is 5 steps, that is, the expansion valve 5 is adjusted according to five times the minimum adjustment unit of the valve (such as 5% opening size). When the second temperature difference T2 is less than 7°C and greater than or equal to 5°C, the valve opening adjustment amount is 2 steps, that is, the expansion valve 5 is adjusted according to twice the minimum adjustment unit of the valve. When the second temperature difference T2 is less than 5°C and greater than or equal to 3°C, the valve opening adjustment amount is 1 step, that is, the expansion valve 5 is adjusted according to the minimum adjustment unit of the valve.

[0139] For example, see Figure 6 Assuming that the second temperature difference T2 at the current moment is 7°C, the controller 20 will not immediately control the expansion valve to reduce the valve opening, but will wait for the system to stabilize for 30 seconds before conducting a detection. Only when the second temperature difference detected after stabilization for 30 seconds still belongs to the temperature range of T2 greater than or equal to 7°C, the controller 20 will combine Table 6 to obtain the valve opening adjustment amount of 5 steps, and then reduce the valve opening of the expansion valve 5 according to five times the minimum adjustment unit of the valve.

[0140] Similarly, if the second temperature difference T2 at the current moment is 5°C, the controller 20 will not immediately control the expansion valve to reduce the valve opening, but wait for the system to stabilize for 30s before testing. Only when the second temperature difference detected after stabilization for 30s still belongs to the temperature range of T2 less than 7°C and greater than or equal to 5°C, the controller 20 will combine Table 6 to obtain the valve opening adjustment amount of 2 steps, and then reduce the valve opening of the expansion valve 5 according to twice the minimum adjustment unit of the valve. If the second temperature difference T2 at the current moment is 3°C, the controller 20 will not immediately control the expansion valve to reduce the valve opening, but wait for the system to stabilize for 30s before testing. Only when the second temperature difference detected after stabilization for 30s still belongs to the temperature range of T2 less than 5°C and greater than or equal to 3°C shown in Table 6, the controller 20 will combine Table 6 to obtain the valve opening adjustment amount of 1 step, and then reduce the valve opening of the expansion valve 5 according to the minimum adjustment unit of the valve.

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

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

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

[0144] Optionally, the controller 20 controls the expansion valve 5 to maintain the valve opening after closing for 30 seconds, and then considers that the system has reached a stable state. At this time, it returns to the above S503 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 air inlet temperature and the water outlet temperature of the air cooler and the second temperature difference between the exhaust temperature and the water inlet 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 is greatly different from the first preset difference range, the controller does not immediately perform frequency increase or frequency decrease operation on the compressor, but controls the compressor to run at the current frequency for a preset time. If the compressor still meets the frequency increase or frequency decrease condition after the preset time, the corresponding frequency adjustment amount is obtained according to Table 2-5, and the operating frequency of the compressor is increased or decreased by the corresponding frequency adjustment amount. When it is determined that the second temperature difference belongs to any temperature interval to be adjusted, the controller does not immediately perform valve closing operation on the expansion valve, but controls the expansion valve to maintain the current valve opening for a preset time. If the expansion valve still meets the valve closing condition after the expansion valve maintains the current valve opening for a preset time, the corresponding valve opening adjustment amount is obtained according to Table 6, and the valve opening of the expansion valve is reduced by the corresponding valve opening adjustment amount. The control process of the entire carbon dioxide heat pump system can not only ensure that the carbon dioxide heat pump system has a high energy efficiency ratio while achieving the target heating capacity, but also effectively ensure that the system has reached a stable state before the controller controls and adjusts the compressor or expansion valve, 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.

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

[0147] Optionally, during the actual operation of the carbon dioxide heat pump system, three common phenomena to be adjusted may occur: the outlet water temperature is too low, the outlet water temperature is too high, and the outlet water temperature is normal but the energy efficiency is low. For the above three common phenomena to be adjusted. Combined with the first temperature difference between the air inlet 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, the phenomenon judgment conditions, causes of the phenomenon and specific control methods are summarized as follows:

[0148] 1. The outlet water temperature is too low: 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 (such as 5%).

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

[0150] 2) The first temperature difference T1 is too small (such as T1 ≤ 21°C): This is manifested as a larger second temperature difference T2 (such as T2> 5°C). The first temperature difference can be increased by reducing the valve opening of the expansion valve, thereby increasing the heat exchange capacity of the air cooler and making the outlet water temperature reach the target outlet water temperature.

[0151] 2. Excessive water outlet temperature: The water outlet temperature is greater than the target water outlet temperature, and the error between the water outlet temperature and the target water outlet temperature is greater than a preset error value (eg, 5%).

[0152] 1) Excessive refrigerant circulation: This is manifested by a large second temperature difference T2 (e.g. T2>5°C). The refrigerant circulation of the system can be reduced by reducing the operating frequency of the compressor, thereby reducing the heat exchange of the air cooler and reducing the outlet water temperature.

[0153] 2) The first temperature difference T1 is too large (such as T1>26℃): This is manifested as a large second temperature difference T2 (such as T2>5℃). The first temperature difference can be reduced by increasing the valve opening of the expansion valve, thereby reducing the heat exchange of the air cooler and reducing 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 (such as 5%).

[0155] 1) Excessive refrigerant circulation: This is manifested by a large second temperature difference T2 (e.g. T2>5°C). The refrigerant circulation of the system can be reduced by reducing the operating frequency of the compressor, thereby extending the time for the unit mass of refrigerant to exchange heat with water in the air cooler and improving the heat exchange efficiency of the air cooler.

[0156] 2) The first temperature difference T1 is too large (such as T1>26℃): This is manifested as a large second temperature difference T2 (such as T2>5℃). The first temperature difference can be reduced by increasing the valve opening of the expansion valve, thereby extending the time for the unit mass of refrigerant to exchange heat with water in the air cooler and improving the heat exchange efficiency of the air cooler.

[0157] It can be seen from the above description that when the three phenomena to be adjusted occur, namely, the outlet water temperature is too low, the outlet water temperature is too high, and the outlet water temperature is normal but the energy efficiency is low, 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 the expansion valve when the second temperature difference exceeds the second preset difference range, to ensure that the carbon dioxide heat pump system has a higher energy efficiency ratio while achieving the target heating amount.

[0158] It can be understood that when the second temperature difference T2 exceeds the second preset difference range (T2≤3℃ or T2>5℃), if 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 capacity of the air cooler and making the outlet water temperature reach the target outlet water temperature.

[0159] When the second temperature difference T2 exceeds the second preset difference range (T2≤3℃ or T2>5℃), if 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 the second and third points in the above description of the phenomenon, the operating frequency of the compressor is reduced and / or the valve opening of the expansion valve is increased. Thereby reducing the heat exchange of the air cooler and reducing the outlet water temperature; or prolonging the time for the unit mass of refrigerant to exchange heat with water in the air cooler and improving the heat exchange efficiency of the air cooler.

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

[0161] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0162] Based on the inventive concept of the control method of the carbon dioxide heat pump system, Figure 7 As shown, the embodiment of the present application also provides a control device 700 of a carbon dioxide heat pump system for implementing the control method of the carbon dioxide heat pump system involved above. Among them, the carbon dioxide heat pump system includes a carbon dioxide circulation loop and a hot water circuit, and 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 water outlet of the hot water circuit; temperature sensors are provided at the first air inlet and the first water outlet, which are respectively used to detect the air intake temperature of the first air inlet and the water outlet temperature of the first water outlet. The control device 700 of the carbon dioxide heat pump system includes:

[0163] The range determination module 701 is used to determine a first preset difference range between the intake air temperature and the outlet water temperature according to the target outlet water temperature;

[0164] The frequency increase control module 702 is used to increase the operating frequency of the compressor when a first temperature difference between the intake air temperature and the outlet water temperature is less than a lower limit of a first preset difference range and a first error value between the lower limit of the first preset difference range and the first temperature difference exceeds a 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 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 the first exhaust port and the first water inlet, which are respectively used to detect the exhaust temperature of the first exhaust port and the water 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 belongs to any temperature interval to be adjusted.

[0168] In one embodiment, the frequency increase control module 702 is also used to determine the first frequency adjustment amount of the compressor according to the difference between the outlet water temperature and the inlet water temperature, the first error value and the ambient temperature 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; and to increase the operating frequency of the compressor by the first frequency adjustment amount.

[0169] In one embodiment, the frequency reduction control module 703 is also used to determine the second frequency adjustment amount of the compressor according to 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 increase control module 702 is also used to control the compressor to run at the current operating frequency for a first preset time period 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; and to 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 also used to control the compressor to run at the current operating frequency for a second preset time period 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 to 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 also used to determine the valve opening adjustment amount corresponding to any temperature interval to be adjusted when the second temperature difference belongs to any temperature interval to be adjusted; different temperature intervals to be adjusted 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 also used to control the expansion valve to maintain the current valve opening for a third preset time when the second temperature difference belongs to any temperature interval to be adjusted, and then determine whether the second temperature difference belongs to any temperature interval to be adjusted; if so, determine the valve opening adjustment amount corresponding to any temperature interval to be adjusted.

[0174] In one embodiment, the control device 700 of the carbon dioxide heat pump system also includes a second temperature difference control module, which is 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 reduce 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.

[0175] The embodiment of the present application also provides an electronic device, which may be a terminal, and its internal structure diagram may be as shown in FIG. Figure 8 As shown. The electronic device includes a processor, a memory, an input / output interface, a communication interface, a display unit and an input device. Among them, the processor, the memory and the input / output interface are connected through a system bus, and the communication interface, the display unit and the input device are connected to the system bus through the input / output interface. Among them, the processor of the electronic device is used to provide computing and control capabilities. The memory of the electronic device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the electronic device is used to exchange information between the processor and an external device. The communication interface of the electronic device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be implemented through WIFI, a mobile cellular network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a control method for a carbon dioxide heat pump system is implemented. The display unit of the electronic device is used to form a visually visible picture, which can be a display screen, a projection device or a virtual reality imaging device. The display screen can be a liquid crystal display screen or an electronic ink display screen, and the input device of the electronic device can be a touch layer covering the display screen, or a button, trackball or touchpad set on the electronic device casing, or an external keyboard, touchpad or mouse.

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

[0177] In one embodiment, an electronic device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the computer program, the following steps are implemented:

[0178] Determining a first preset difference range between the intake air temperature and the outlet water temperature according to the target outlet water temperature;

[0179] In the case where a first temperature difference between the intake air temperature and the outlet water temperature is less than a lower limit of a first preset difference range, and a first error value between the lower limit of the first preset difference range and the first temperature difference exceeds a first preset error value, increasing the operating frequency of the compressor;

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

[0181] In one embodiment, when the processor executes the computer program, the following steps are further implemented: when the second temperature difference between the exhaust temperature and the inlet water temperature belongs to any temperature interval to be adjusted, reducing the valve opening of the expansion valve.

[0182] In one embodiment, when the processor executes the computer program, the following steps are also implemented: 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 according to the difference between the outlet water temperature and the inlet water temperature, the first error value and the ambient temperature; and the operating frequency of the compressor is increased by the first frequency adjustment amount.

[0183] In one embodiment, when the processor executes the computer program, the following steps are also implemented: 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 according to 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, the processor also implements the following steps when executing the computer program: 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.

[0185] In one embodiment, the processor also implements the following steps when executing the computer program: 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.

[0186] In one embodiment, when the processor executes the computer program, the following steps are also implemented: when the second temperature difference belongs to any temperature interval to be adjusted, the valve opening adjustment amount corresponding to any temperature interval to be adjusted is determined; different temperature intervals to be adjusted correspond to different valve opening adjustment amounts; and the valve opening of the expansion valve is reduced by the valve opening adjustment amount.

[0187] In one embodiment, the processor also implements the following steps when executing the computer program: when the second temperature difference belongs to any temperature interval 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 interval to be adjusted; if so, determine the valve opening adjustment amount corresponding to any temperature interval to be adjusted.

[0188] In one embodiment, the processor further implements the following steps when executing the computer program: when a second temperature difference between the exhaust temperature and the water inlet 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 value 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 reduce 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.

[0189] The present application also provides a computer storage medium, which stores instructions, and when the instructions are executed on a computer or a processor, the computer or the processor executes one or more steps in the above embodiment. If the components of the above electronic device are implemented in the form of software functional units and sold or used as independent products, they can be stored in the above computer readable storage medium.

[0190] In one embodiment, a computer storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the following steps are implemented:

[0191] Determining a first preset difference range between the intake air temperature and the outlet water temperature according to the target outlet water temperature;

[0192] In the case where a first temperature difference between the intake air temperature and the outlet water temperature is less than a lower limit of a first preset difference range, and a first error value between the lower limit of the first preset difference range and the first temperature difference exceeds a first preset error value, increasing the operating frequency of the compressor;

[0193] When the first temperature difference is greater than an upper limit of a first preset difference range and a second error value between the first temperature difference and the upper limit of the first preset difference range exceeds a 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, the following steps are also implemented: when the second temperature difference between the exhaust temperature and the inlet water temperature belongs to any temperature interval to be adjusted, reducing the valve opening of the expansion valve.

[0195] In one embodiment, when the computer program is executed by the processor, the following steps are also implemented: 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 according to the difference between the outlet water temperature and the inlet water temperature, the first error value and the ambient temperature; and the operating frequency of the compressor is increased by the first frequency adjustment amount.

[0196] In one embodiment, when the computer program is executed by the processor, the following steps are also implemented: 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 according to 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, the following steps are also implemented: 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 compressor is controlled to run at the current operating 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 according to 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, the following steps are also implemented: 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 compressor is controlled to run at the current operating frequency for a second preset time period, 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.

[0199] In one embodiment, when the computer program is executed by the processor, the following steps are also implemented: when the second temperature difference belongs to any temperature interval to be adjusted, the valve opening adjustment amount corresponding to any temperature interval to be adjusted is determined; different temperature intervals to be adjusted correspond to different valve opening adjustment amounts; and the valve opening of the expansion valve is reduced by the valve opening adjustment amount.

[0200] In one embodiment, when the computer program is executed by the processor, the following steps are also implemented: when the second temperature difference belongs to any temperature interval 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 temperature interval to be adjusted; if so, the valve opening adjustment amount corresponding to any temperature interval to be adjusted is determined.

[0201] In one embodiment, when the computer program is executed by the processor, the following steps are also implemented: when a second temperature difference between the exhaust temperature and the water inlet 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 value 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 reduce 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.

[0202] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of 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, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. 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 a website site, computer, server or data center to another website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (Digital Subscriber Line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode. The computer storage medium can be any available medium that a computer can access or a data storage device such as a server, data center, etc. that contains one or more available media integrated. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a digital versatile disc (DVD)), or a semiconductor medium (eg, a solid state disk (SSD)).

[0203] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk and other media that can store program codes. In the absence of conflict, the technical features in this embodiment and the implementation scheme can be combined arbitrarily.

[0204] The embodiments described above are merely preferred embodiments of the present application and are not intended to limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements made to the technical solutions of the present application by ordinary technicians in this field should fall within the protection scope determined by the claims.

[0205] The above describes a specific embodiment of the present application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous 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 comprises a carbon dioxide circulation loop and a hot water circuit, wherein the carbon dioxide circulation loop comprises a compressor and an air cooler; a first air inlet of the air cooler is connected to an exhaust port of the compressor, and a first water outlet of the air cooler is connected to a water outlet of the hot water circuit; temperature sensors are provided at the first air inlet and the first water outlet, respectively for detecting an air inlet temperature of the first air inlet and a water outlet temperature of the first water outlet; the method comprises: Determining a first preset difference range between the intake air temperature and the outlet water temperature according to the target outlet water temperature; In the case where a first temperature difference between the intake air temperature and the outlet water temperature is less than a lower limit of the first preset difference range, and a first error value between the lower limit of the first preset difference range and the first temperature difference exceeds a first preset error value, increasing the operating frequency of the compressor; When the first temperature difference is greater than an upper limit of the first preset difference range and a second error value between the first temperature difference and the upper limit of the first preset difference range exceeds a second preset error value, the operating frequency of the compressor is reduced.

2. The method according to 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 the first exhaust port and the first water inlet, which are respectively used to detect the exhaust temperature of the first exhaust port and the water inlet temperature of the first water inlet.

3. The method according to claim 2, characterized in that The method further comprises: When the second temperature difference between the exhaust temperature and the inlet water temperature belongs to any temperature interval to be adjusted, the valve opening of the expansion valve is reduced.

4. The method according to claim 2, characterized in that When the first temperature difference between the intake 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 comprises: 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 according to 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 according to claim 2, characterized in that When the first temperature difference is greater than the upper limit of the first preset difference range, and a second error value between the first temperature difference and the upper limit of the first preset difference range exceeds a second preset error value, reducing the operating frequency of the compressor comprises: 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 according to 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 according to claim 4, characterized in that The first frequency adjustment amount of the compressor is determined according to the difference between the outlet water temperature and the inlet water temperature, the first error value, and the ambient temperature 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, including: 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 operate at the current operating frequency for a first preset time, 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 according to the difference between the outlet water temperature and the inlet water temperature, the first error value, and the ambient temperature.

7. The method according to claim 5, characterized in that The method further comprises: determining a second frequency adjustment amount of the compressor according to a difference between the outlet water temperature and the inlet water temperature, the second error value, and an ambient temperature when the first temperature difference value is greater than an upper limit of the first preset difference value range and the second error value exceeds the second preset error value, comprising: 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 operate at the current operating frequency for a second preset time, 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 according to the difference between the outlet water temperature and the inlet water temperature, the second error value and the ambient temperature.

8. The method according to claim 3, characterized in that When the second temperature difference between the exhaust temperature and the inlet water temperature belongs to any temperature interval to be adjusted, reducing the valve opening of the expansion valve comprises: In the case where the second temperature difference belongs to any one of the temperature intervals to be adjusted, determining the valve opening adjustment amount corresponding to the any one of the temperature intervals to be adjusted; different valve opening adjustment amounts correspond to different temperature intervals to be adjusted; The valve opening of the expansion valve is reduced by the valve opening adjustment amount.

9. The method according to claim 8, characterized in that When the second temperature difference belongs to any one of the temperature intervals to be adjusted, determining the valve opening adjustment amount corresponding to the any one of the temperature intervals to be adjusted includes: In the case where the second temperature difference belongs to any one of the temperature intervals 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 one of the temperature intervals to be adjusted; If so, determine the valve opening adjustment amount corresponding to any one of the temperature intervals to be adjusted.

10. The method according to claim 2, characterized in that The method further comprises: When a second temperature difference between the exhaust temperature and the water inlet temperature exceeds a second preset difference range, determining whether the water outlet temperature is less than the target water outlet temperature and whether an error between the water outlet temperature and the target water outlet temperature is greater than a preset error value; If yes, then increasing the operating frequency of the compressor and / or reducing the valve opening of the expansion valve; If not, the operating frequency of the compressor is reduced, and / or the valve opening of the expansion valve is increased.

11. A control device for a carbon dioxide heat pump system, characterized in that: The carbon dioxide heat pump system comprises a carbon dioxide circulation loop and a hot water circuit, wherein the carbon dioxide circulation loop comprises 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 water outlet of the hot water circuit; the first air inlet and the first water outlet are both provided with temperature sensors, which are used to detect the air intake temperature of the first air inlet and the water outlet temperature of the first water outlet respectively; the device comprises: a range determination module, configured to determine a first preset difference range between the intake air temperature and the outlet water temperature according to a target outlet water temperature; a frequency increase control module, configured to increase the operating frequency of the compressor when a first temperature difference between the intake air temperature and the outlet water temperature is less than a lower limit of the first preset difference range, and a first error value between the lower limit of the first preset difference range and the first temperature difference exceeds a 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 implements the method steps of any one of claims 1 to 10 when executing the computer program.

13. A computer storage medium, characterized in that: The computer storage medium stores a plurality of instructions, which are suitable for being loaded by a processor and executing the method steps according to any one of claims 1 to 10.

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