Control method and device of heat pump system, electronic equipment and computer storage medium

Abstract

The invention provides a control method and device of a heat pump system, electronic equipment and a computer storage medium, the heat pump system comprises a refrigerant circulation loop, a first bypass branch and a heating water way, and the refrigerant circulation loop comprises an evaporator, a compressor, an air cooler and a heat regenerator; the first bypass branch is connected with the refrigerant circulation loop, and the method comprises the steps that when a defrosting instruction is detected, the return air superheat degree of the heat pump system is obtained; under the condition that the return air superheat degree is larger than or equal to the target return air superheat degree, the pressure intensity difference value of the high pressure and the low pressure of the heat pump system is determined; and under the condition that the pressure intensity difference value is not smaller than the preset pressure intensity difference value, the working frequency of the compressor is adjusted till the pressure intensity difference value is smaller than the preset pressure intensity difference value, the first bypass valve is controlled to be opened, and the heat pump system enters a defrosting mode and defrosts the evaporator. According to the embodiment provided by the scheme, the defrosting safety and reliability of the heat pump system are improved.

Description

Technical Field

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

[0002] In the related art, during the frosting process of the heat pump system, the wind resistance becomes larger due to the influence of the frost layer, the heat exchange effect of the external heat exchanger gradually becomes worse, the proportion of the liquid refrigerant component gradually increases, and the evaporation temperature becomes lower. When the heat pump system is defrosted, the refrigerant in the external heat exchanger releases heat to the frost layer and becomes a two-phase refrigerant with a lower dryness, which is prone to compressor liquid hammer, resulting in low reliability of compressor operation; in addition, when the heat pump system enters the defrost mode, the defrost bypass valve opens at the moment, and the large pressure difference and high flow rate of the bypass passage will cause drastic fluctuations in the flow field pressure in the pipeline, which can easily cause the pipeline to vibrate, and then cause serious consequences such as noise, valve damage and even pipe burst, which leads to low reliability of defrosting of the heat pump system. Summary of the invention

[0003] The present application provides a control method, device, electronic device and computer storage medium for a heat pump system, which can improve the safety and reliability of defrosting of the heat pump system. The above technical solutions are as follows:

[0004] In a first aspect, an embodiment of the present application provides a control method for a heat pump system, wherein the heat pump system comprises a refrigerant circulation loop, a first bypass branch and a hot water circuit, wherein the refrigerant circulation loop comprises an evaporator, a compressor, an air cooler and a regenerator; an air inlet of the air cooler is connected to an exhaust port of the compressor, an exhaust port of the air cooler is connected to a high temperature side inlet of the regenerator, and a water outlet of the air cooler is connected to a water outlet of the hot water circuit; the first bypass branch is connected to the refrigerant circulation loop, and the first bypass branch comprises a first bypass valve and a capillary tube connected in series; the method comprises:

[0005] When a defrost command is detected, the return air superheat of the heat pump system is obtained;

[0006] When the return air superheat is greater than or equal to the target return air superheat, determining the pressure difference between the high pressure and the low pressure of the heat pump system;

[0007] When the pressure difference is not less than the preset pressure difference, the operating frequency of the compressor is adjusted until the pressure difference is less than the preset pressure difference, and the first bypass valve is controlled to open, so that the heat pump system enters the defrost mode and defrosts the evaporator.

[0008] In a possible implementation, the refrigerant circulation loop further includes a throttling element, the inlet of the evaporator is connected to the outlet of the throttling element, the inlet of the throttling element is connected to the high-temperature side outlet of the regenerator, and the outlet of the evaporator is connected to the low-temperature side inlet of the regenerator;

[0009] The above method further includes:

[0010] When the return air superheat is less than the target return air superheat, the opening of the throttling element is reduced to control at least part of the liquid refrigerant in the evaporator to migrate to the air cooler. When the return air superheat is greater than or equal to the target return air superheat, the step of determining the pressure difference between the high pressure and the low pressure of the heat pump system is performed.

[0011] In a possible implementation, the first end of the first bypass branch is connected to the inlet of the evaporator, and the second end of the first bypass branch is connected to the exhaust port of the compressor.

[0012] In a possible implementation, the heat pump system further includes a second bypass branch, the second bypass branch includes a second bypass valve and a heat exchanger, the inlet of the second bypass valve is connected to the outlet of the throttling element, and the outlet of the second bypass valve is connected to the inlet of the evaporator; the water inlet of the heat exchanger is connected to the water outlet of the air cooler, and the water outlet of the heat exchanger is connected to the water outlet of the hot water circuit; the air inlet of the heat exchanger is connected to the outlet of the throttling element, and the air outlet of the heat exchanger is connected to the inlet of the evaporator;

[0013] The above method further includes:

[0014] When the heat pump system enters the defrost mode, controlling the second bypass valve to close;

[0015] When the heat pump system exits the defrost mode, the second bypass valve is controlled to open.

[0016] In a possible implementation, the adjusting of the operating frequency of the compressor includes:

[0017] Obtaining the water outlet temperature of the water outlet of the air cooler;

[0018] Determine the temperature difference between the outlet water temperature and the critical temperature or quasi-critical temperature of the refrigerant in the heat pump system;

[0019] Determine whether the temperature difference is greater than or equal to a preset temperature difference;

[0020] When the temperature difference is greater than or equal to the preset temperature difference, the operating frequency of the compressor is reduced.

[0021] In a possible implementation, a temperature sensor is provided at the water outlet of the air cooler for detecting the outlet water temperature of the water outlet of the air cooler.

[0022] In a possible implementation, the hot water circuit includes a water pump, and the adjusting the operating frequency of the compressor further includes:

[0023] When the temperature difference is less than the preset temperature difference, the operating frequency of the water pump is increased, and the step of obtaining the outlet water temperature of the air cooler is returned to execute until it is determined that the pressure difference is less than the preset pressure difference, and the first bypass valve is controlled to open.

[0024] In a possible implementation, after controlling the first bypass valve to open, the method further includes:

[0025] The opening degree of the throttling element is adjusted based on the target return air superheat so as to control the return air superheat of the heat pump system to be equal to or greater than the target return air superheat in the defrost mode.

[0026] In a possible implementation, the refrigerant circulation loop further includes an external fan, and the external fan is connected to the evaporator. The method further includes:

[0027] After the first bypass valve is controlled to open, the external fan is controlled to stop running.

[0028] In a possible implementation, after controlling the first bypass valve to open, the method further includes:

[0029] obtaining the low pressure of the heat pump system;

[0030] When it is detected that the low pressure reaches a preset low pressure threshold, the external fan is controlled to operate;

[0031] When the operating time of the above-mentioned external fan reaches the preset operating time, the above-mentioned heat pump system is controlled to exit the above-mentioned defrosting mode.

[0032] In a second aspect, an embodiment of the present application provides a control device for a heat pump system, the heat pump system comprising a refrigerant circulation loop, a first bypass branch and a hot water circuit, the refrigerant circulation loop comprising an evaporator, a compressor, an air cooler and a regenerator; the air inlet of the air cooler is connected to the exhaust port of the compressor, the exhaust port of the air cooler is connected to the high temperature side inlet of the regenerator, and the water outlet of the air cooler is connected to the water outlet of the hot water circuit; the first bypass branch is connected to the refrigerant circulation loop, and the first bypass branch comprises a first bypass valve and a capillary tube connected in series; the device comprises:

[0033] A first acquisition module is used to acquire the return air superheat of the heat pump system when a defrost instruction is detected;

[0034] A determination module, used for determining the pressure difference between the high pressure and the low pressure of the heat pump system when the return air superheat is greater than or equal to the target return air superheat;

[0035] The first control module is used to adjust the operating frequency of the compressor when the pressure difference is not less than the preset pressure difference, until the pressure difference is less than the preset pressure difference, and then control the first bypass valve to open, so that the heat pump system enters the defrost mode and defrosts the evaporator.

[0036] In a possible implementation, the refrigerant circulation loop further includes a throttling element, the inlet of the evaporator is connected to the outlet of the throttling element, the inlet of the throttling element is connected to the high-temperature side outlet of the regenerator, and the outlet of the evaporator is connected to the low-temperature side inlet of the regenerator;

[0037] The control device further comprises:

[0038] The second control module is used to reduce the opening of the throttling element when the return air superheat is less than the target return air superheat, so as to control at least part of the liquid refrigerant in the evaporator to migrate to the air cooler, until the return air superheat is greater than or equal to the target return air superheat, and then execute the step of determining the pressure difference between the high pressure and the low pressure of the heat pump system.

[0039] In a possible implementation, the first end of the first bypass branch is connected to the inlet of the evaporator, and the second end of the first bypass branch is connected to the exhaust port of the compressor.

[0040] In a possible implementation, the heat pump system further includes a second bypass branch, the second bypass branch includes a second bypass valve and a heat exchanger, the inlet of the second bypass valve is connected to the outlet of the throttling element, and the outlet of the second bypass valve is connected to the inlet of the evaporator; the water inlet of the heat exchanger is connected to the water outlet of the air cooler, and the water outlet of the heat exchanger is connected to the water outlet of the hot water circuit; the air inlet of the heat exchanger is connected to the outlet of the throttling element, and the air outlet of the heat exchanger is connected to the inlet of the evaporator;

[0041] The control device further comprises:

[0042] A third control module, configured to control the second bypass valve to close when the heat pump system enters the defrost mode;

[0043] The fourth control module is used to control the second bypass valve to open when the heat pump system exits the defrost mode.

[0044] In a possible implementation, the first control module includes:

[0045] An acquisition unit, used for acquiring the outlet water temperature of the water outlet of the air cooler;

[0046] A determination unit, used to determine the temperature difference between the above-mentioned outlet water temperature and the critical temperature or quasi-critical temperature of the refrigerant in the above-mentioned heat pump system;

[0047] A judging unit, used to judge whether the temperature difference is greater than or equal to a preset temperature difference;

[0048] The first control unit is used to reduce the operating frequency of the compressor when the temperature difference is greater than or equal to the preset temperature difference.

[0049] In a possible implementation, a temperature sensor is provided at the water outlet of the air cooler for detecting the outlet water temperature of the water outlet of the air cooler.

[0050] In a possible implementation, the hot water circuit includes a water pump, and the first control module further includes:

[0051] The second control unit is used to increase the operating frequency of the water pump when the above-mentioned temperature difference is less than the above-mentioned preset temperature difference, and return to execute the above-mentioned step of obtaining the outlet water temperature of the water outlet of the above-mentioned air cooler until it is determined that the above-mentioned pressure difference is less than the above-mentioned preset pressure difference, and control the above-mentioned first bypass valve to open.

[0052] In a possible implementation, the control device further includes:

[0053] The fifth control module is used to adjust the opening of the throttling element based on the target return air superheat after controlling the opening of the first bypass valve, so as to control the return air superheat of the heat pump system to be equal to or greater than the target return air superheat in the defrost mode.

[0054] In a possible implementation, the refrigerant circulation loop further includes an external fan, the external fan is connected to the evaporator, and the control device further includes:

[0055] The sixth control module is used to control the above-mentioned external fan to stop running after controlling the above-mentioned first bypass valve to open.

[0056] In a possible implementation, the control device further includes:

[0057] A second acquisition module, configured to acquire the low pressure of the heat pump system after controlling the first bypass valve to open;

[0058] A seventh control module, configured to control the operation of the external fan when it is detected that the low pressure reaches a preset low pressure threshold;

[0059] The eighth control module is used to control the heat pump system to exit the defrost mode when the operating time of the above-mentioned external fan reaches a preset operating time.

[0060] In a third aspect, an embodiment of the present application provides an electronic device, including: a processor and a memory;

[0061] The above-mentioned memory stores a computer program, and the above-mentioned computer program is suitable for being loaded by the above-mentioned processor and executing the steps of the method provided by the first aspect of the embodiment of the present application or any possible implementation method of the first aspect.

[0062] In a fourth aspect, an embodiment of the present application provides a computer storage medium, which stores multiple instructions, and the instructions are suitable for being loaded by a processor and executing the steps of the method provided by the first aspect of the embodiment of the present application or any possible implementation method of the first aspect.

[0063] The heat pump system in the embodiment of the present application includes a refrigerant circulation loop, a first bypass branch and a hot water circuit, the refrigerant circulation loop includes an evaporator, a compressor, an air cooler and a regenerator; the air inlet of the air cooler is connected to the exhaust port of the compressor, the exhaust port of the air cooler is connected to the high-temperature side inlet of the regenerator, and the water outlet of the air cooler is connected to the water outlet of the hot water circuit; the first bypass branch is connected to the refrigerant circulation loop, and the first bypass branch includes a first bypass valve and a capillary tube connected in series. By acquiring the return air superheat of the heat pump system when a defrost command is detected, and determining the pressure difference between the high pressure and the low pressure of the heat pump system when the return air superheat is greater than or equal to the target return air superheat, and then adjusting the operating frequency of the compressor when the pressure difference is not less than the preset pressure difference, until the pressure difference is less than the preset pressure difference, the first bypass valve is controlled to open, so that the heat pump system enters the defrost mode and defrosts the evaporator, it can be ensured that the return air superheat of the heat pump system reaches a certain value before defrosting, thereby reducing the storage of liquid refrigerant in the evaporator and reducing the probability of compressor liquid hammer; in addition, by adjusting the high and low pressure differences of the compressor frequency adjustment system to determine the opening time of the first bypass valve, it can be avoided that at the moment of opening the first bypass valve, the large pressure difference and high flow rate of the bypass branch will cause drastic fluctuations in the flow field pressure in the pipeline, thereby reducing the probability of serious consequences such as pipeline vibration, noise, valve damage and even pipe burst. In this way, while reducing the probability of compressor liquid hammer, it also reduces the probability of serious consequences such as pipeline vibration, noise, valve damage and even pipe burst, adding multiple safeguards for the subsequent defrosting process, greatly improving the safety and reliability of heat pump system defrosting. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] 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.

[0065] Figure 1a A schematic diagram of an application scenario of a control method for a heat pump system provided by an exemplary embodiment of the present application;

[0066] Figure 1b A schematic diagram of pressure-enthalpy changes of a heat pump system during a defrosting process provided by an exemplary embodiment of the present application;

[0067] Figure 2 A schematic diagram of another application scenario of a control method for a heat pump system provided by an exemplary embodiment of the present application;

[0068] Figure 3 A schematic diagram of an application environment of a control method for a heat pump system provided by an exemplary embodiment of the present application;

[0069] Figure 4 A flow chart of a control method for a heat pump system provided by an exemplary embodiment of the present application;

[0070] Figure 5 A specific flow chart of a control method for a heat pump system provided by an exemplary embodiment of the present application;

[0071] Figure 6 A schematic structural diagram of a control device for a heat pump system provided by an exemplary embodiment of the present application;

[0072] Figure 7 A schematic structural diagram of an electronic device provided as an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0073] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0074] The terms "first", "second", "third", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0075] See also Figure 1a First, an application scenario applicable to the embodiment of the present application is introduced: the heat pump system 10 applied to a high-temperature water heater includes a refrigerant circulation loop 11, a first bypass branch 12 and a hot water circuit 13. The refrigerant circulation loop 11 and the first bypass branch 12 are used for the circulation of the refrigerant, and the hot water circuit 13 is used for the circulation of water. Among them, the refrigerant can be carbon dioxide. As a natural working fluid that is harmless to the environment, carbon dioxide has a global warming potential (GWP) of 1 and an ozone depletion potential (ODP) of 0. It has a high refrigeration capacity per unit volume, excellent flow and heat transfer characteristics, and can significantly reduce the size of the compressor and the system. It is one of the main choices for new refrigerants. It can be used in subcritical circulation systems for refrigeration and freezing, and can also be used in transcritical circulation systems for heat pump water heaters.

[0076] In some embodiments, the refrigerant circulation loop 11 includes a compressor 101, an air cooler 102, a regenerator 103, a throttling element 104, an evaporator 105, and an external fan 106; the first bypass branch 12 includes a first bypass valve 107 and a capillary tube 108, and the hot water circuit 13 includes a water inlet 109 and a water outlet 110. Specifically, the first bypass valve 107 can be a solenoid valve.

[0077] The outlet of the evaporator 105 is connected to the regenerator 103, the compressor 101, and the air cooler 102 in sequence through pipelines, and then connected to the throttling element 104 through the regenerator 103, and the throttling element 104 is connected back to the inlet of the evaporator 105 through a pipeline, thereby forming a refrigerant circulation loop 11. That is, the outlet of the evaporator 105 is connected to the low-temperature side inlet 1031 of the regenerator 103 through a pipeline, the low-temperature side outlet 1032 of the regenerator 103 is connected to the return air port of the compressor 101 through a pipeline, the exhaust port of the compressor 101 is connected to the air inlet 1021 of the air cooler 102 through a pipeline, the exhaust port 1022 of the air cooler 102 is connected to the high-temperature side inlet 1033 of the regenerator 103 through a pipeline, the high-temperature side outlet 1034 of the regenerator 103 is connected to the inlet of the throttling element 104 through a pipeline, and then the outlet of the throttling element 104 is connected back to the inlet of the evaporator 105.

[0078] In some embodiments, the first end of the first bypass branch 12 is connected to the inlet of the evaporator 105, and the second end of the first bypass branch is connected to the exhaust port of the compressor 101. Specifically, the first bypass branch 12 formed by the first bypass valve 107 and the capillary tube 108 in series is connected to the refrigerant circulation loop 11, and the first end of the first bypass branch 12 is connected to the inlet of the evaporator 105 through a pipeline, and the second end is connected to the exhaust port of the compressor 101 through a pipeline; the water inlet 109 and the water outlet 110 of the hot water circuit 13 are respectively connected to the water inlet 1023 and the water outlet 1024 of the air cooler 102, so that the refrigerant circulation loop 11 and the hot water circuit 13 perform heat exchange through the air cooler 102. That is, the air cooler 102 includes a portion of the refrigerant circulation circuit 11 disposed between the air inlet 1021 and the air outlet 1022 , and a portion of the hot water circuit 13 disposed between the water inlet 1023 and the water outlet 1024 .

[0079] In the hot water making mode, the working process of the heat pump system 10 is as follows: Taking carbon dioxide as the refrigerant as an example, after carbon dioxide absorbs heat in the evaporator 105 and becomes low-temperature carbon dioxide steam, it enters the low-temperature side inlet 1031 of the regenerator 103, and performs heat exchange with the high-temperature carbon dioxide steam returned from the air cooler 102 in the regenerator 103 to form preheated carbon dioxide steam. The preheated carbon dioxide steam enters the return air port of the compressor 101 from the low-temperature side outlet 1032 of the regenerator 103, and is compressed into high-temperature and high-pressure carbon dioxide steam in the compressor 101. The high-temperature and high-pressure carbon dioxide steam flows out from the exhaust port of the compressor 101 and enters the air inlet 1021 of the air cooler 102, releasing a large amount of heat in the air cooler 102 to heat the water entering from the water inlet 1023 of the air cooler 102. The heated water flows out from the water outlet 1024 of the air cooler 102, and the cooled high-temperature and high-pressure carbon dioxide steam returns to the regenerator 103 from the high-temperature side inlet 1033 of the regenerator 103 to be reheated, and then flows out from the high-temperature side outlet 1034 of the regenerator 103, and returns to the evaporator 105 through the throttling element 104, thereby completing a cycle.

[0080] The present application is described below in conjunction with the pressure-enthalpy diagram of the heat pump system 10 in the defrost mode. Figure 1b A schematic diagram of a pressure-enthalpy change of a heat pump system during a defrosting process provided by an exemplary embodiment of the present application. The pressure-enthalpy diagram refers to a curve diagram of pressure and enthalpy values. Figure 1b The horizontal axis H in represents the enthalpy value, which is used to describe the change of heat. The enthalpy value is used to represent the energy state of the fluid. The vertical axis LgP represents the logarithmic pressure, which is used to show the pressure change of the fluid under different states. Figure 1b The curve in shows the enthalpy and pressure changes of the refrigerant (refrigerant) in different states in the heat pump system 10.

[0081] Specifically, Figure 1b The numbers marked in the rectangular boxes in the figure correspond to different devices or process steps. For example, 1 to 2 represent the compression process, the refrigerant changes from low pressure to high pressure, and the enthalpy increases; 2 to 3 represent the condensation process, the refrigerant dissipates heat in the air cooler 102, the pressure remains high but the enthalpy decreases.

[0082] Specifically, in the defrost mode, the first bypass valve 107 is opened, and the refrigerant in state 1 enters the compressor 101. The flow path and heat exchange superheat of a part of the high-temperature and high-pressure refrigerant (state 2) discharged from the compressor 101 are consistent with those in the above-mentioned hot water making mode, that is, it enters the air inlet 1021 of the air cooler 102, and releases a large amount of heat in the air cooler 102 to heat the water entering from the water inlet 1023 of the air cooler 102. The heated water flows out from the water outlet 1024 of the air cooler 102, and the cooled high-temperature and high-pressure carbon dioxide vapor (state 4) returns to the regenerator 103 from the high-temperature side inlet 1033 of the regenerator 103 for reheating; and another part of the refrigerant will pass through the first bypass valve 107, and be throttled into a low-temperature and low-pressure gas state (state 3) by the capillary 108, and then mix with the above-mentioned two-phase refrigerant (state 6) after throttling by the main throttling element 104 to become state 7 and enter the evaporator 105 to exchange heat with the frost layer. Further, the refrigerant (state 8) cooled by the frost layer enters the low-pressure side of the regenerator 103 to achieve superheating, and finally returns to the compressor 101 in state 1.

[0083] Optionally, the heat pump system 10 also includes a temperature sensor for detecting the evaporation temperature in the evaporator 105, the air intake temperature of the air inlet 1021 of the air cooler 102, the exhaust temperature of the exhaust port 1022 of the air cooler 102, the water inlet temperature of the water inlet 1023 of the air cooler 102, the water outlet temperature of the water outlet 1024 of the air cooler 102, and the ambient temperature, etc.

[0084] Optionally, the hot water circuit 13 may further include a water pump 111 . The outlet of the water pump 111 is connected to the water inlet 109 of the hot water circuit 13 .

[0085] In some embodiments, the heat pump system may further include a second bypass branch. Figure 2 Another application scenario applicable to the embodiment of the present application is introduced: the heat pump system 20 applied to the high-temperature water heater includes a refrigerant circulation loop 21, a first bypass branch 22 and a hot water circuit 23. The refrigerant circulation loop 21 and the first bypass branch 22 are used for the circulation of refrigerant (such as carbon dioxide), and the hot water circuit 23 is used for water circulation. The above-mentioned refrigerant circulation loop 21 includes a compressor 201, an air cooler 202 (including an air inlet 2021, an exhaust port 2022, a water inlet 2023 and a water outlet 2024), a regenerator 203, a throttling element 204, an evaporator 205 and an external fan 206; the first bypass branch 22 includes a first bypass valve 207 and a capillary tube 208, and the hot water circuit 23 includes a water inlet 209, a water outlet 210 and a water pump 211. The connection between the various components is consistent with the heat pump system 10 shown in Figure 1 above, and will not be repeated here.

[0086] On the basis of the above structure, the heat pump system 20 further includes a second bypass branch 24, which includes a second bypass valve 213 and a heat exchanger 214. The inlet of the second bypass valve 213 is connected to the outlet of the throttling element 204, and the outlet of the second bypass valve 213 is connected to the inlet of the evaporator 205. The water inlet 2141 of the heat exchanger 214 is connected to the water outlet 2024 of the air cooler 202, the water outlet 2142 of the heat exchanger 214 is connected to the water outlet 210 of the hot water circuit 23, the air inlet 2143 of the heat exchanger 214 is connected to the outlet of the throttling element 204, and the air outlet 2144 of the heat exchanger 214 is connected to the inlet of the evaporator 205.

[0087] In the embodiment of the present application, when the heat pump system 20 operates in the hot water making mode, the second bypass valve 213 is opened and the heat exchanger 214 is bypassed; when the heat pump system 20 enters the defrosting mode and the first bypass valve 107 is opened for formal defrosting, the second bypass valve 213 is closed, and the refrigerant at the low pressure side and relatively low temperature after throttling enters the heat exchanger 214 to exchange heat with the water at a higher temperature, and then enters the evaporator 205 for defrosting. In this way, the heat of the heat pump system 20 during defrosting comes from the work of the compressor 201 on the one hand, and from the heat absorbed from the water on the other hand. The embodiment of the present application can shorten the defrosting time, thereby improving the defrosting efficiency.

[0088] It is worth noting that this embodiment only describes the 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 heat pump system 10 or the heat pump system 20 (including but not limited to the evaporator, the regenerator, the compressor, the air cooler, the first bypass valve, the temperature sensor, the second bypass valve, the heat exchanger, etc.), and technicians in this field can set them according to actual conditions.

[0089] The control method of the heat pump system provided in the embodiment of the present application can be applied to Figure 3In the application environment shown. Taking the above-mentioned heat pump system 10 as an example, the controller 30 communicates with the heat pump system 10. Specifically, when the defrost command is detected, the controller 30 obtains the return air superheat of the above-mentioned heat pump system 10; when the above-mentioned return air superheat is greater than or equal to the target return air superheat, the pressure difference between the high pressure and the low pressure of the above-mentioned heat pump system 10 is determined; when the above-mentioned pressure difference is not less than the preset pressure difference, the operating frequency of the compressor 101 is adjusted until the above-mentioned pressure difference is less than the above-mentioned preset pressure difference, and the above-mentioned first bypass valve 107 is controlled to open, so that the above-mentioned heat pump system 10 enters the defrost mode and defrosts the above-mentioned evaporator 105. Among them, the controller 30 can at least obtain the detection result uploaded by the pressure sensor in the heat pump system 10, and control the operating frequency of the compressor 101 according to the detection result uploaded by the pressure sensor, etc., which is not limited in this application. It is understandable that the controller 30 can be either the original controller of the heat pump system 10 or a controller separately set up to execute the control method of the heat pump system of the present application. Those skilled in the art can set the structure and model of the controller 30 according to actual usage requirements.

[0090] An exemplary embodiment of the present application provides a control method for a heat pump system. The control method for a heat pump system can be applied to the controller 30 described above. Figure 4 , which exemplarily shows a flow chart of a control method of a heat pump system provided in an embodiment of the present application. Figure 4 As shown, the control method of the heat pump system includes the following S41-S43:

[0091] S41. When a defrost command is detected, the return air superheat of the heat pump system is obtained.

[0092] The defrost instruction is an instruction for controlling the heat pump system 10 to enter a defrost mode. Specifically, the defrost instruction can be triggered when the heat pump system 10 is in a hot water making mode.

[0093] In some embodiments, the controller 30 can detect the temperature of the surface of the evaporator 105 through a temperature sensor or other detection device. When the temperature is lower than the preset frost temperature threshold, it can be considered that a frost layer is formed. Then, the controller 30 can obtain the difference between the return air temperature Th at the return air port of the compressor 101 and the evaporation temperature Te of the refrigerant from the above-mentioned compressor 101, and use the difference as the return air superheat of the heat pump system 10. The difference reflects the evaporation state of the refrigerant in the evaporator 105.

[0094] S42. When the return air superheat is greater than or equal to the target return air superheat, determine the pressure difference between the high pressure and the low pressure of the heat pump system.

[0095] In some embodiments, the high pressure and the low pressure of the heat pump system 10 may be acquired by a pressure sensor disposed in the heat pump system 10 .

[0096] In some embodiments, the target return air superheat is a preset minimum return air superheat SH1.

[0097] The high pressure of the heat pump system 10 can be expressed as Pc, the low pressure can be expressed as Pe, and the pressure difference can be expressed as Pc-Pe.

[0098] S43. When the pressure difference is not less than the preset pressure difference, the operating frequency of the compressor is adjusted until the pressure difference is less than the preset pressure difference, and the first bypass valve is controlled to open, so that the heat pump system enters the defrost mode and defrosts the evaporator.

[0099] In some embodiments, the preset pressure difference value is a preset maximum pressure difference threshold ΔPmax.

[0100] After the first bypass valve 107 is controlled to open, the heat pump system 10 enters the defrost mode and defrosts the evaporator 105, so that part of the high-temperature gas passing through the compressor 101 enters the evaporator 105 for defrosting after the flow and pressure are adjusted by the capillary 108.

[0101] In the defrost mode, the first bypass valve 107 is opened, and the refrigerant enters the compressor 101. The flow path and heat exchange superheat of a part of the high-temperature and high-pressure refrigerant discharged from the compressor 101 are consistent with those in the above-mentioned hot water making mode, that is, it enters the air inlet 1021 of the air cooler 102, and releases a large amount of heat in the air cooler 102 to heat the water entering from the water inlet 1023 of the air cooler 102. The heated water flows out from the water outlet 1024 of the air cooler 102, and the cooled high-temperature and high-pressure carbon dioxide vapor returns to the regenerator 103 from the high-temperature side inlet 1033 of the regenerator 103 to be reheated; and another part of the refrigerant will pass through the first bypass valve 107, and be throttled into a low-temperature and low-pressure gas through the capillary 108, and then mixed with the above-mentioned two-phase refrigerant throttled by the main throttling element 104 and enter the evaporator 105 to exchange heat with the frost layer. Further, the refrigerant cooled by the frost layer enters the low-pressure side of the regenerator 103 to be superheated, and finally returns to the compressor 101.

[0102] The above embodiment reduces the high and low pressure difference of the heat pump system 10 to determine the opening time of the first bypass valve 107, thereby avoiding the reliability risk of obvious pipeline vibration caused by the large pressure difference when the first bypass valve 107 is opened.

[0103] The heat pump system in the embodiment of the present application includes a refrigerant circulation loop, a first bypass branch and a hot water circuit, the refrigerant circulation loop includes an evaporator, a compressor, an air cooler and a regenerator; the air inlet of the air cooler is connected to the exhaust port of the compressor, the exhaust port of the air cooler is connected to the high-temperature side inlet of the regenerator, and the water outlet of the air cooler is connected to the water outlet of the hot water circuit; the first bypass branch is connected to the refrigerant circulation loop, and the first bypass branch includes a first bypass valve and a capillary tube connected in series. By acquiring the return air superheat of the heat pump system when a defrost command is detected, and determining the pressure difference between the high pressure and the low pressure of the heat pump system when the return air superheat is greater than or equal to the target return air superheat, and then adjusting the operating frequency of the compressor when the pressure difference is not less than the preset pressure difference, until the pressure difference is less than the preset pressure difference, the first bypass valve is controlled to open, so that the heat pump system enters the defrost mode and defrosts the evaporator, it can be ensured that the return air superheat of the heat pump system reaches a certain value before defrosting, thereby reducing the storage of liquid refrigerant in the evaporator and reducing the probability of compressor liquid hammer; in addition, by adjusting the high and low pressure differences of the compressor frequency adjustment system to determine the opening time of the first bypass valve, it can be avoided that at the moment of opening the first bypass valve, the large pressure difference and high flow rate of the bypass branch will cause drastic fluctuations in the flow field pressure in the pipeline, thereby reducing the probability of serious consequences such as pipeline vibration, noise, valve damage and even pipe burst. In this way, while reducing the probability of compressor liquid hammer, it also reduces the probability of serious consequences such as pipeline vibration, noise, valve damage and even pipe burst, adding multiple safeguards for the subsequent defrosting process, greatly improving the safety and reliability of heat pump system defrosting.

[0104] In some embodiments, the above method further comprises:

[0105] S44. When the return air superheat is less than the target return air superheat, reduce the opening of the throttling element to control at least part of the liquid refrigerant in the evaporator to migrate to the air cooler, until the return air superheat is greater than or equal to the target return air superheat, and execute the step of determining the pressure difference between the high pressure and the low pressure of the heat pump system.

[0106] In some embodiments, in the step of reducing the opening of the throttling element, the opening EXV of the throttling element 104 can be adjusted with the return air superheat (Th-Te) ≥ SH1 as the control target, thereby realizing the migration of part of the liquid refrigerant on the evaporator side to the air cooler side.

[0107] In some embodiments, the value of SH1 is greater than the value of return air superheat SH in hot water making mode.

[0108] In some embodiments, to ensure that the return air is superheated at the initial stage of defrosting, the external fan 106 maintains the original speed in the hot water making mode.

[0109] In the embodiment of the present application, the time period from when the defrost command is received to when the first bypass valve 107 is opened is the initial stage of defrosting. When the heat pump system 10 is in the hot water making mode, as the frost layer on the evaporator 105 thickens, its heat exchange effect gradually deteriorates, and it is more difficult for the throttled two-phase refrigerant to absorb heat in the evaporator 105 and become an overheated state. At this time, the liquid refrigerant component in the evaporator 105 accounts for a large proportion. Therefore, before formal defrosting (i.e., the initial stage of defrosting), the opening of the throttling element 104 is reduced, and part of the liquid refrigerant in the evaporator 105 is transferred to the air cooler 102 until the return air superheat is greater than or equal to the target return air superheat. This can reduce the proportion of liquid refrigerant in the evaporator 105, thereby reducing the probability of liquid hammer, and improving the reliability and safety of the operation of the heat pump system 10 in the initial stage of defrosting.

[0110] In some embodiments, in S43, the operating frequency of the compressor is adjusted, including S431-S434:

[0111] S431, obtaining the water outlet temperature of the water outlet of the air cooler.

[0112] Wherein, the water outlet of the above-mentioned air cooler may be provided with a temperature sensor for detecting the outlet water temperature Tgc,o.

[0113] S432: Determine the temperature difference between the outlet water temperature and the critical temperature or pseudo-critical temperature of the refrigerant in the heat pump system.

[0114] The critical temperature Tc of the refrigerant refers to the temperature of the refrigerant at the critical pressure, at which the liquid and gas phases of the refrigerant cannot be distinguished, that is, the gas and liquid phases are in equilibrium. Tc is a fixed temperature value, which is determined by the chemical properties of the refrigerant and does not change with pressure.

[0115] The pseudo-critical temperature Tpc is a parameter of supercritical fluid, which is mainly used to describe the properties of fluid in supercritical state. When the pressure of the refrigerant exceeds its critical pressure, the refrigerant enters the supercritical state, at which time its gas-liquid boundary disappears, and the traditional gas-liquid equilibrium theory is no longer applicable. In the supercritical state, the properties of the refrigerant are between liquid and gas. Tpc is a temperature parameter used to describe the properties of the refrigerant in this special state. Tpc changes with the pressure, and it is a temperature value related to pressure.

[0116] In some embodiments, when the high pressure Pc of the heat pump system is less than the critical pressure Pcr (the critical pressure Pcr of carbon dioxide is 7.3773 MPa), the temperature difference between the above-mentioned water outlet temperature and the critical temperature of the refrigerant in the above-mentioned heat pump system is determined; when the high pressure Pc of the heat pump system ≥ the critical pressure Pcr, the temperature difference between the above-mentioned water outlet temperature and the critical temperature of the refrigerant in the above-mentioned heat pump system is determined.

[0117] Specifically, the pseudo-critical temperature of carbon dioxide is Tpc=-122.6+6.124*(Pc / 100)-0.1657*(Pc / 100)2+0.01773*(Pc / 100)2.5-0.0005608*(Pc / 100)3+273.15 (wherein the unit of Pc is bar and the unit of Tpc is Kelvin K).

[0118] S433: Determine whether the temperature difference is greater than or equal to a preset temperature difference.

[0119] The preset temperature difference may be expressed as SC1.

[0120] S434. When the temperature difference is greater than or equal to the preset temperature difference, reduce the operating frequency of the compressor.

[0121] In the embodiment of the present application, by detecting the temperature difference and reducing the operating frequency of the compressor, the ineffective energy loss can be reduced while the heat pump system works effectively, and excessive operation of the compressor can be avoided, the service life of the compressor can be extended, and failures caused by overheating or overloading can be prevented.

[0122] In some embodiments, when the water pump 111 is included in the hot water circuit 13, in S43, the operating frequency of the compressor is adjusted, and S435 is also included:

[0123] S435. When the temperature difference is less than the preset temperature difference, increase the operating frequency of the water pump, and return to execute the step of obtaining the outlet water temperature of the air cooler until it is determined that the pressure difference is less than the preset pressure difference, and then control the first bypass valve to open.

[0124] Optionally, when the pressure difference (Pc-Pe) is greater than or equal to the preset pressure difference ΔPmax, the operating frequency of the water pump 111 is first adjusted according to the refrigerant subcooling (Tgc,o-Tc) or quasi-subcooling (Tgc,o-Tpc) at the outlet of the air cooler 102. Specifically, when the refrigerant subcooling (Tgc,o-Tc) or quasi-subcooling (Tgc,o-Tpc) is less than the preset temperature difference SC1, the operating frequency of the water pump 111 is increased, and then the operating frequency of the compressor 101 is reduced, until the pressure difference (Pc-Pe) is less than the preset pressure difference ΔPmax, the first bypass valve 107 is opened, and the defrosting begins in the middle of the defrosting period.

[0125] In the embodiment of the present application, the high and low pressure difference (Pc-Pe) of the heat pump system 10 is taken as the control target to coordinately adjust the operating frequency Fpump of the water pump 111 and the operating frequency Ft of the compressor 101, so as to enhance the condensing capacity on the high-pressure side, thereby increasing the average density ρ of the refrigerant and reducing its specific volume v (v=1 / ρ) to enhance the condensing capacity on the high-pressure side, thereby increasing the condensing temperature and condensing pressure of the refrigerant, thereby achieving the purpose of reducing the high pressure of the heat pump system, and then realizing the regulation of the high and low pressure difference.

[0126] In the embodiment of the present application, by combining the coordinated regulation of the water pump frequency and the compressor frequency, it is possible to effectively avoid fluctuations or instability in the heat pump system when the high and low pressure differences are large, thereby protecting the compressor and other components, preventing equipment damage, and improving the stability and reliability of the heat pump system operation.

[0127] In some embodiments, after controlling the first bypass valve to open, the method further includes:

[0128] S45. Adjust the opening of the throttling element based on the target return air superheat to control the return air superheat of the heat pump system to be equal to or greater than the target return air superheat in the defrost mode.

[0129] Specifically, after the first bypass valve 107 is controlled to open, the heat pump system 10 enters the middle stage of defrosting, and the opening of the throttling element 104 is adjusted with the return air superheat (Th-Te) ≥ SH as the control target.

[0130] Superheat reflects the degree to which the temperature of the refrigerant gas is higher than the evaporation temperature. If the superheat is too low, liquid refrigerant may enter the compressor, causing a "liquid hammer" phenomenon, thereby damaging the compressor. In the embodiment of the present application, by adjusting the opening of the throttling element and controlling the return air superheat, the compressor can be effectively protected, avoiding the compressor from inhaling incompletely vaporized refrigerant, thereby improving the operating reliability of the compressor and extending its service life.

[0131] In some embodiments, when the refrigerant circulation loop 11 includes an external fan 106, the method further includes: S46, after controlling the first bypass valve to open, controlling the external fan to stop running.

[0132] In the embodiment of the present application, in the defrost mode, the external fan 106 is controlled to stop running, so as to avoid the refrigerant releasing heat and condensing in the evaporator 105 during the defrost process, causing part of the heat of the refrigerant to be lost in the air, thereby saving defrost time and improving defrost efficiency.

[0133] In some embodiments, the method further includes: S47, in the defrost mode, the water pump operates at a fixed lower frequency Fpump to avoid the refrigerant being in a two-phase state before throttling and generating noise.

[0134] In some embodiments, after controlling the first bypass valve to open, the method further includes:

[0135] S48, obtaining the low pressure of the heat pump system; when it is detected that the low pressure reaches a preset low pressure threshold, controlling the operation of the external fan.

[0136] S49. When the operating time of the external fan reaches a preset operating time, the heat pump system is controlled to exit the defrosting mode.

[0137] Specifically, when it is detected that the low pressure Pe of the heat pump system gradually increases to a preset low pressure threshold value Pe_def_final, the above-mentioned external fan is controlled to run for a preset running time t seconds, and finally exits the defrost mode.

[0138] In an embodiment of the present application, in the defrost mode, as the frost layer gradually melts during the defrost process, the evaporation temperature gradually rises, entering the late stage of defrost. The external fan can be turned on to use the wind speed to carry away the loose frost particles to promote defrost, further shortening the defrost time and improving the defrost efficiency.

[0139] In some embodiments, when the heat pump system includes the second bypass branch, the method further includes: when the heat pump system enters the defrost mode, controlling the second bypass valve to close; when the heat pump system exits the defrost mode, controlling the second bypass valve to open.

[0140] With the above Figure 2For example, the heat pump system 20 includes a second bypass branch. When the heat pump system 20 is in the hot water making mode, the second bypass valve 213 is opened and the heat exchanger 214 is bypassed; when the heat pump system 20 enters the defrost mode and the first bypass valve 107 is opened for formal defrosting, the second bypass valve 213 is closed, and the refrigerant at the low pressure side and with a relatively low temperature after throttling enters the heat exchanger 214 to exchange heat with the water with a higher temperature, and then enters the evaporator 205 for defrosting.

[0141] In the embodiment of the present application, the heat of the heat pump system 20 during defrosting comes from the work done by the compressor 201 on the one hand, and from absorbing heat from the water on the other hand. The embodiment of the present application can shorten the defrosting time and thus improve the defrosting efficiency.

[0142] Furthermore, the present application is described below in conjunction with specific embodiments. Figure 5 A specific flow chart of a control method for a heat pump system provided by an exemplary embodiment of the present application is as follows: Figure 5 As shown, the control method of the heat pump system includes the following steps S501-S518, wherein the initial defrosting includes S501-S510, the initial defrosting includes S511-S514, and the initial defrosting includes S515-S518:

[0143] S501. When a defrost command is detected, the return air superheat of the heat pump system is obtained.

[0144] Specifically, S501 is consistent with S41 and will not be described in detail here.

[0145] S502, determine whether the return air superheat is greater than or equal to the target return air superheat; if not, execute S503, and if so, execute S504.

[0146] S503: Reduce the opening of the throttling element.

[0147] Specifically, S502-S503 are consistent with S44 and will not be repeated here.

[0148] S504, determine whether the pressure difference is less than the preset pressure difference; if not, execute S505, and if so, execute S510.

[0149] S505: Obtain the water outlet temperature of the water outlet of the air cooler.

[0150] S506: Determine the temperature difference between the outlet water temperature and the critical temperature or pseudo-critical temperature of the refrigerant in the heat pump system.

[0151] S507, determine whether the temperature difference is greater than or equal to the preset temperature difference; if not, execute S508, and if so, execute S509.

[0152] S508. Increase the operating frequency of the water pump.

[0153] S509: Reduce the operating frequency of the compressor.

[0154] S510, controlling the first bypass valve to open.

[0155] Specifically, S504-S510 are consistent with S431-S435 and will not be repeated here.

[0156] S511, controlling the external fan to stop running, and controlling the water pump to run at a fixed lower operating frequency.

[0157] Specifically, S511 is consistent with S46-S47 and will not be repeated here.

[0158] S512: Control the compressor to defrost at a fixed operating frequency.

[0159] Optionally, the operating frequency of the compressor is adjusted to maintain the compressor running at a preset target defrost frequency Ft_def.

[0160] S513. Determine whether the return air superheat is greater than or equal to the target return air superheat; if not, execute S514; if yes, execute S515.

[0161] S514. Reduce the opening of the throttling element.

[0162] Specifically, S513-S514 are consistent with S45 and will not be repeated here.

[0163] S515, determine whether the low pressure reaches the preset low pressure threshold; if so, execute S516, if not, execute S512.

[0164] S516, control the operation of the external fan.

[0165] S517: It is detected that the external fan has been running for a preset running time.

[0166] S518: Control the heat pump system to exit the defrost mode.

[0167] Specifically, S515-S518 are consistent with S48-S49 and will not be repeated here.

[0168] In the embodiment of the present application, the defrosting process is divided into three stages: the initial stage of defrosting, the middle stage of defrosting and the late stage of defrosting, and is precisely controlled. In the initial stage of defrosting, the operating frequency of the throttling element and the compressor is adjusted by monitoring the return air superheat, the pressure difference and other parameters. This precise initial control can lay a good foundation for the system to enter the formal defrosting, so that the system can quickly adapt to the needs of defrosting and avoid unnecessary waste of resources. In the middle stage of defrosting, the heat pump system enters the formal defrosting mode. At this time, by controlling the operating frequency of the compressor and the water pump, the defrosting process is carried out smoothly and reliably, and the defrosting efficiency is improved. In the late stage of defrosting, the heat pump system gradually returns to normal working state, controls the start of the external fan and ensures that the system exits the defrosting mode smoothly. Reasonable late management can enable the heat pump system to quickly return to the optimal operating state after the defrosting is completed, reducing unnecessary delays or energy losses. Through the combination of the early, middle and late stages, the heat pump system can maintain a good state at each stage of defrosting, reduce the defrosting time, and thus improve the defrosting efficiency.

[0169] In addition, in the early stage of defrosting, by monitoring and adjusting the return air superheat, it is ensured that the refrigerant will not enter the compressor in liquid form, preventing the occurrence of liquid hammer, effectively protecting the compressor and other components, avoiding damage to the equipment due to overload, and extending its service life. In the medium term, by controlling the frequency of the compressor and water pump, the stability of the system during the defrosting process is improved, and excessive temperature and pressure fluctuations during the defrosting process are prevented, further protecting the equipment and components in the heat pump system. The later fan control can also prevent the equipment from overworking, reduce wear, avoid unnecessary operation of the external fan, further save energy, and smoothly transition to the normal working mode, ensuring a smooth recovery process after defrosting, and reducing unnecessary fluctuations during system startup and shutdown. This multi-stage precise control can optimize each stage of the defrosting process and improve the operating efficiency and reliability of the entire heat pump system.

[0170] Please refer to the following Figure 6 , which is a schematic diagram of the structure of a control device of a heat pump system provided by an exemplary embodiment of the present application. The above-mentioned refrigerant circulation loop includes an evaporator, a compressor, an air cooler and a regenerator; the air inlet of the above-mentioned air cooler is connected to the exhaust port of the above-mentioned compressor, the exhaust port of the above-mentioned air cooler is connected to the high-temperature side inlet of the above-mentioned regenerator, and the water outlet of the above-mentioned air cooler is connected to the water outlet of the above-mentioned hot water circuit; the above-mentioned first bypass branch is connected to the above-mentioned refrigerant circulation loop, and the above-mentioned first bypass branch includes a first bypass valve and a capillary tube connected in series; Figure 6 As shown, the control device 600 of the heat pump system includes:

[0171] The first acquisition module 601 is used to acquire the return air superheat of the heat pump system when a defrost instruction is detected;

[0172] A determination module 602 is used to determine the pressure difference between the high pressure and the low pressure of the heat pump system when the return air superheat is greater than or equal to the target return air superheat;

[0173] The first control module 603 is used to adjust the operating frequency of the compressor when the pressure difference is not less than the preset pressure difference, until the pressure difference is less than the preset pressure difference, and then control the first bypass valve to open, so that the heat pump system enters the defrost mode and defrosts the evaporator.

[0174] In a possible implementation, the refrigerant circulation loop further includes a throttling element, the inlet of the evaporator is connected to the outlet of the throttling element, the inlet of the throttling element is connected to the high-temperature side outlet of the regenerator, and the outlet of the evaporator is connected to the low-temperature side inlet of the regenerator;

[0175] The control device 600 further includes:

[0176] The second control module is used to reduce the opening of the throttling element when the return air superheat is less than the target return air superheat, so as to control at least part of the liquid refrigerant in the evaporator to migrate to the air cooler, until the return air superheat is greater than or equal to the target return air superheat, and then execute the step of determining the pressure difference between the high pressure and the low pressure of the heat pump system.

[0177] In a possible implementation, the first end of the first bypass branch is connected to the inlet of the evaporator, and the second end of the first bypass branch is connected to the exhaust port of the compressor.

[0178] In a possible implementation, the heat pump system further includes a second bypass branch, the second bypass branch includes a second bypass valve and a heat exchanger, the inlet of the second bypass valve is connected to the outlet of the throttling element, and the outlet of the second bypass valve is connected to the inlet of the evaporator; the water inlet of the heat exchanger is connected to the water outlet of the air cooler, and the water outlet of the heat exchanger is connected to the water outlet of the hot water circuit; the air inlet of the heat exchanger is connected to the outlet of the throttling element, and the air outlet of the heat exchanger is connected to the inlet of the evaporator;

[0179] The control device 600 further includes:

[0180] A third control module, configured to control the second bypass valve to close when the heat pump system enters the defrost mode;

[0181] The fourth control module is used to control the second bypass valve to open when the heat pump system exits the defrost mode.

[0182] In a possible implementation, the first control module 603 includes:

[0183] An acquisition unit, used for acquiring the outlet water temperature of the water outlet of the air cooler;

[0184] A determination unit, used to determine the temperature difference between the above-mentioned outlet water temperature and the critical temperature or quasi-critical temperature of the refrigerant in the above-mentioned heat pump system;

[0185] A judging unit, used to judge whether the temperature difference is greater than or equal to a preset temperature difference;

[0186] The first control unit is used to reduce the operating frequency of the compressor when the temperature difference is greater than or equal to the preset temperature difference.

[0187] In a possible implementation, a temperature sensor is provided at the water outlet of the air cooler for detecting the outlet water temperature of the water outlet of the air cooler.

[0188] In a possible implementation, the hot water circuit includes a water pump, and the first control module 603 further includes:

[0189] The second control unit is used to increase the operating frequency of the water pump when the above-mentioned temperature difference is less than the above-mentioned preset temperature difference, and return to execute the above-mentioned step of obtaining the outlet water temperature of the water outlet of the above-mentioned air cooler until it is determined that the above-mentioned pressure difference is less than the above-mentioned preset pressure difference, and control the above-mentioned first bypass valve to open.

[0190] In a possible implementation, the control device 600 further includes:

[0191] The fifth control module is used to adjust the opening of the throttling element based on the target return air superheat after controlling the opening of the first bypass valve, so as to control the return air superheat of the heat pump system to be equal to or greater than the target return air superheat in the defrost mode.

[0192] In a possible implementation, the refrigerant circulation loop further includes an external fan, the external fan is connected to the evaporator, and the control device 600 further includes:

[0193] The sixth control module is used to control the above-mentioned external fan to stop running after controlling the above-mentioned first bypass valve to open.

[0194] In a possible implementation, the control device 600 further includes:

[0195] A second acquisition module, configured to acquire the low pressure of the heat pump system after controlling the first bypass valve to open;

[0196] A seventh control module, configured to control the operation of the external fan when it is detected that the low pressure reaches a preset low pressure threshold;

[0197] The eighth control module is used to control the heat pump system to exit the defrost mode when the operating time of the above-mentioned external fan reaches a preset operating time.

[0198] The division of each module in the control device 600 of the heat pump system is only for illustration. In other embodiments, the control device of the heat pump system can be divided into different modules as needed to complete all or part of the functions of the control device of the heat pump system. The implementation of each module in the control device of the heat pump system provided in the embodiment of this specification can be in the form of a computer program. The computer program can be run on a terminal or a server. The program module composed of the computer program can be stored in the memory of the terminal or the server. When the computer program is executed by the processor, all or part of the steps of the control method of the heat pump system described in the embodiment of this specification are implemented.

[0199] See next Figure 7 , which is a schematic diagram of the structure of an electronic device provided by an exemplary embodiment of the present application. Figure 7 As shown, the electronic device 700 may include: a processor 710 and a memory 720 , and may also include a user interface 730 , a network interface 740 and a communication bus 750 .

[0200] Among them, the processor 710 may include one or more processing cores. The processor 710 uses various interfaces and lines to connect various parts of the entire electronic device 700, and executes various functions and processes data of the electronic device 700 by running or executing instructions, programs, code sets or instruction sets stored in the memory 720, and calling data stored in the memory 720. Optionally, the processor 710 can be implemented in at least one hardware form of digital signal processing (Digital Signal Processing, DSP), field programmable gate array (Field-Programmable Gate Array, FPGA), and programmable logic array (Programmable Logic Array, PLA). The processor 710 can integrate one or a combination of a central processing unit (Central Processing Unit, CPU), a graphics processing unit (Graphics Processing Unit, GPU) and a modem. Among them, the CPU mainly processes operating systems and applications, etc.; the GPU is responsible for rendering and drawing the content to be displayed on the display screen; the modem is used to process wireless communications. It can be understood that the above-mentioned modem may not be integrated into the processor 710, and it can be implemented separately through a chip.

[0201] Among them, the memory 720 may include a random access memory (Random Access Memory, RAM) and may also include a read-only memory (Read-Only Memory). Optionally, the memory 720 includes a non-transitory computer-readable storage medium. The memory 720 can be used to store instructions, programs, codes, code sets or instruction sets. The memory 720 may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for at least one function (such as a receiving function, a control function, etc.), instructions for implementing the above-mentioned various method embodiments, etc.; the data storage area may store data involved in the above-mentioned various method embodiments, etc. The memory 720 may also be optionally at least one storage device located away from the aforementioned processor 710. As Figure 7 As shown, the memory 720 as a computer storage medium may include an operating system, a network communication module, a user interface module, and program instructions.

[0202] Optionally, the communication bus 750 is used to realize the connection and communication between these components. The user interface 730 may include a display screen (Display), a camera (Camera), and may also include a standard wired interface and a wireless interface; the network interface 740 may optionally include a standard wired interface and a wireless interface (such as a WI FI interface).

[0203] exist Figure 7 In the electronic device 700 shown, the processor 710 may be used to call program instructions stored in the memory 720 and specifically perform the following operations:

[0204] When a defrost command is detected, the return air superheat of the heat pump system is obtained;

[0205] When the return air superheat is greater than or equal to the target return air superheat, determining the pressure difference between the high pressure and the low pressure of the heat pump system;

[0206] When the pressure difference is not less than the preset pressure difference, the operating frequency of the compressor is adjusted until the pressure difference is less than the preset pressure difference, and the first bypass valve is controlled to open, so that the heat pump system enters the defrost mode and defrosts the evaporator.

[0207] In a possible implementation, the refrigerant circulation loop further includes a throttling element, the inlet of the evaporator is connected to the outlet of the throttling element, the inlet of the throttling element is connected to the high-temperature side outlet of the regenerator, and the outlet of the evaporator is connected to the low-temperature side inlet of the regenerator;

[0208] The above method further includes:

[0209] When the return air superheat is less than the target return air superheat, the opening of the throttling element is reduced to control at least part of the liquid refrigerant in the evaporator to migrate to the air cooler. When the return air superheat is greater than or equal to the target return air superheat, the step of determining the pressure difference between the high pressure and the low pressure of the heat pump system is performed.

[0210] In a possible implementation, the first end of the first bypass branch is connected to the inlet of the evaporator, and the second end of the first bypass branch is connected to the exhaust port of the compressor.

[0211] In a possible implementation, the heat pump system further includes a second bypass branch, the second bypass branch includes a second bypass valve and a heat exchanger, the inlet of the second bypass valve is connected to the outlet of the throttling element, and the outlet of the second bypass valve is connected to the inlet of the evaporator; the water inlet of the heat exchanger is connected to the water outlet of the air cooler, and the water outlet of the heat exchanger is connected to the water outlet of the hot water circuit; the air inlet of the heat exchanger is connected to the outlet of the throttling element, and the air outlet of the heat exchanger is connected to the inlet of the evaporator;

[0212] The above method further includes:

[0213] When the heat pump system enters the defrost mode, controlling the second bypass valve to close;

[0214] When the heat pump system exits the defrost mode, the second bypass valve is controlled to open.

[0215] In a possible implementation, the adjusting of the operating frequency of the compressor includes:

[0216] Obtaining the water outlet temperature of the water outlet of the air cooler;

[0217] Determine the temperature difference between the outlet water temperature and the critical temperature or quasi-critical temperature of the refrigerant in the heat pump system;

[0218] Determine whether the temperature difference is greater than or equal to a preset temperature difference;

[0219] When the temperature difference is greater than or equal to the preset temperature difference, the operating frequency of the compressor is reduced.

[0220] In a possible implementation, a temperature sensor is provided at the water outlet of the air cooler for detecting the outlet water temperature of the water outlet of the air cooler.

[0221] In a possible implementation, the hot water circuit includes a water pump, and the adjusting the operating frequency of the compressor further includes:

[0222] When the temperature difference is less than the preset temperature difference, the operating frequency of the water pump is increased, and the step of obtaining the outlet water temperature of the air cooler is returned to execute until it is determined that the pressure difference is less than the preset pressure difference, and the first bypass valve is controlled to open.

[0223] In a possible implementation, after controlling the first bypass valve to open, the method further includes:

[0224] The opening degree of the throttling element is adjusted based on the target return air superheat so as to control the return air superheat of the heat pump system to be equal to or greater than the target return air superheat in the defrost mode.

[0225] In a possible implementation, the refrigerant circulation loop further includes an external fan, and the external fan is connected to the evaporator. The method further includes:

[0226] After the first bypass valve is controlled to open, the external fan is controlled to stop running.

[0227] In a possible implementation, after controlling the first bypass valve to open, the method further includes:

[0228] obtaining a low pressure from the heat pump system;

[0229] When it is detected that the low pressure reaches a preset low pressure threshold, the external fan is controlled to operate;

[0230] When the operating time of the above-mentioned external fan reaches the preset operating time, the above-mentioned heat pump system is controlled to exit the above-mentioned defrosting mode.

[0231] The present application also provides a computer-readable 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 various component modules of the control device of the heat pump system 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.

[0232] 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 above-mentioned computer program product includes one or more computer instructions. When the above-mentioned computer program instructions are loaded and executed on a computer, the above-mentioned process or function according to the embodiment of the present application is generated in whole or in part. The above-mentioned computer can be a general-purpose computer, a special-purpose computer, a computer network or other programmable devices. The above-mentioned computer instructions can be stored in a computer-readable storage medium or transmitted by the above-mentioned computer-readable storage medium. The above-mentioned computer instructions can be transmitted from a website site, a computer, a server or a data center to another website site, a computer, a server or a data center by wired (such as coaxial cable, optical fiber, digital subscriber line (Digital Subscriber Line, DSL)) or wireless (such as infrared, wireless, microwave, etc.) mode. The above-mentioned computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server, a data center, etc. that contains one or more available media integrated. The above-mentioned available media can be magnetic media (for example, floppy disks, hard disks, tapes), optical media (for example, digital versatile discs (DVD)), or semiconductor media (for example, solid state disks (SSD)), etc.

[0233] 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.

[0234] The above-mentioned embodiments 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 of the present application.

Claims

1. A control method for a heat pump system, characterized in that: The heat pump system comprises a refrigerant circulation loop, a first bypass branch and a hot water circuit, wherein the refrigerant circulation loop comprises an evaporator, a compressor, an air cooler and a regenerator; the air inlet of the air cooler is connected to the exhaust port of the compressor, the exhaust port of the air cooler is connected to the high temperature side inlet of the regenerator, and the water outlet of the air cooler is connected to the water outlet of the hot water circuit; The first bypass branch is connected to the refrigerant circulation loop, and the first bypass branch includes a first bypass valve and a capillary tube connected in series; the method includes: When a defrost instruction is detected, obtaining the return air superheat of the heat pump system; When the return air superheat is greater than or equal to the target return air superheat, determining the pressure difference between the high pressure and the low pressure of the heat pump system; When the pressure difference is not less than a preset pressure difference, the operating frequency of the compressor is adjusted until the pressure difference is less than the preset pressure difference, and the first bypass valve is controlled to open, so that the heat pump system enters a defrost mode and defrosts the evaporator.

2. The method according to claim 1, characterized in that The refrigerant circulation loop further includes a throttling element, the inlet of the evaporator is connected to the outlet of the throttling element, the inlet of the throttling element is connected to the high-temperature side outlet of the regenerator, and the outlet of the evaporator is connected to the low-temperature side inlet of the regenerator; The method further comprises: When the return air superheat is less than the target return air superheat, the opening of the throttling element is reduced to control at least part of the liquid refrigerant in the evaporator to migrate to the air cooler. Until the return air superheat is greater than or equal to the target return air superheat, the step of determining the pressure difference between the high pressure and the low pressure of the heat pump system is performed.

3. The method according to claim 1, characterized in that A first end of the first bypass branch is connected to the inlet of the evaporator, and a second end of the first bypass branch is connected to the exhaust port of the compressor.

4. The method according to claim 2, characterized in that The heat pump system further comprises a second bypass branch, wherein the second bypass branch comprises a second bypass valve and a heat exchanger, wherein the inlet of the second bypass valve is connected to the outlet of the throttling element, and the outlet of the second bypass valve is connected to the inlet of the evaporator; the water inlet of the heat exchanger is connected to the water outlet of the air cooler, and the water outlet of the heat exchanger is connected to the water outlet of the hot water circuit; The air inlet of the heat exchanger is connected to the outlet of the throttling element, and the air outlet of the heat exchanger is connected to the inlet of the evaporator; The method further comprises: When the heat pump system enters the defrost mode, controlling the second bypass valve to close; When the heat pump system exits the defrost mode, the second bypass valve is controlled to open.

5. The method according to claim 1, characterized in that The step of adjusting the operating frequency of the compressor comprises: Obtaining the water outlet temperature of the water outlet of the air cooler; Determining the temperature difference between the outlet water temperature and the critical temperature or quasi-critical temperature of the refrigerant in the heat pump system; Determining whether the temperature difference is greater than or equal to a preset temperature difference; When the temperature difference is greater than or equal to the preset temperature difference, the operating frequency of the compressor is reduced.

6. The method according to claim 5, characterized in that A temperature sensor is provided at the water outlet of the air cooler for detecting the outlet water temperature of the water outlet of the air cooler.

7. The method according to claim 5, characterized in that The hot water circuit includes a water pump, and the adjusting the operating frequency of the compressor also includes: When the temperature difference is less than the preset temperature difference, the operating frequency of the water pump is increased, and the step of obtaining the outlet water temperature of the air cooler is returned to execute until it is determined that the pressure difference is less than the preset pressure difference, and the first bypass valve is controlled to open.

8. The method according to claim 2, characterized in that After controlling the first bypass valve to open, the method further includes: The opening degree of the throttling element is adjusted based on the target return air superheat degree to control the return air superheat degree of the heat pump system to be equal to or greater than the target return air superheat degree in the defrost mode.

9. The method according to claim 1, characterized in that The refrigerant circulation loop also includes an external fan, and the external fan is connected to the evaporator. The method also includes: After the first bypass valve is controlled to open, the external fan is controlled to stop running.

10. The method according to claim 9, characterized in that After controlling the first bypass valve to open, the method further includes: obtaining a low pressure of the heat pump system; When it is detected that the low pressure reaches a preset low pressure threshold, controlling the external fan to operate; When the operating time of the external fan reaches a preset operating time, the heat pump system is controlled to exit the defrost mode.

11. A control device for a heat pump system, characterized in that: The heat pump system comprises a refrigerant circulation loop, a first bypass branch and a hot water circuit, wherein the refrigerant circulation loop comprises an evaporator, a compressor, an air cooler and a regenerator; the air inlet of the air cooler is connected to the exhaust port of the compressor, the exhaust port of the air cooler is connected to the high temperature side inlet of the regenerator, and the water outlet of the air cooler is connected to the water outlet of the hot water circuit; the first bypass branch is connected to the refrigerant circulation loop, and the first bypass branch comprises a first bypass valve and a capillary tube connected in series; the control device comprises: A first acquisition module, configured to acquire the return air superheat of the heat pump system when a defrost instruction is detected; A determination module, configured to determine a pressure difference between a high pressure and a low pressure of the heat pump system when the return air superheat is greater than or equal to a target return air superheat; The first control module is used to adjust the operating frequency of the compressor when the pressure difference is not less than a preset pressure difference, until the pressure difference is less than the preset pressure difference, and then control the first bypass valve to open, so that the heat pump system enters a defrost mode and defrosts the evaporator.

12. An electronic device, characterized in that: include: Processor and memory; The memory stores a computer program, and the computer program is suitable for being loaded by the processor and executing the steps of the method according to any one of claims 1 to 10.

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

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