Control method of heat pump unit, heat pump unit and computer program product

Abstract

The invention relates to a heat pump unit, a control method of the heat pump unit and a computer program product, and the control method comprises the steps that a refrigerant system is started and controlled according to a first control strategy, and the first control strategy has at least one control parameter; in response to exhaust protection shutdown of the compressor, the control parameters are adjusted to update the first control strategy, and a second control strategy is obtained; and starting and controlling the refrigerant system according to the second control strategy. According to the heat pump unit and the control method thereof, the problem of dead lock caused by control according to the same control strategy after multiple times of starting can be prevented, normal operation of the unit is guaranteed for a long time, and then the operation duration of the heat pump unit is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of heat pumps, and particularly to a control method for a heat pump unit, a heat pump unit, and a computer program product. Background Art

[0002] Exhaust temperature overprotection is a common fault of air source heat pump units. During the operation of the unit, corresponding control strategies are adopted to avoid the occurrence of exhaust protection faults. Of course, this control strategy cannot completely avoid exhaust protection. When the exhaust temperature protection shutdown occurs, the heat pump unit will start again after reaching the start-up condition. After the heat pump unit starts again, it still executes the current control strategy. After the exhaust protection shutdown occurs, the exhaust protection shutdown is still likely to occur easily during subsequent operation. This makes the heat pump unit prone to consecutive exhaust protection shutdowns, and further makes the heat pump unit locked due to multiple exhaust protection shutdowns and unable to operate normally. Summary of the Invention

[0003] In view of the above problems, the present invention is proposed to provide a control method for a heat pump unit, a heat pump unit, and a computer program product that overcome the above problems or at least partially solve the above problems, so as to prevent the heat pump unit from experiencing exhaust protection shutdown as much as possible, and further prevent consecutive exhaust protection shutdowns as much as possible, thereby reducing the probability of being locked and increasing the operation duration of the heat pump unit.

[0004] Specifically, the present invention provides a control method for a heat pump unit, the heat pump unit includes a refrigerant system for making hot water, and the refrigerant system includes a compressor; the control method of the heat pump unit includes:

[0005] Starting and controlling the refrigerant system according to a first control strategy, the first control strategy having at least one control parameter;

[0006] In response to the compressor exhaust protection shutdown, adjusting the control parameter to update the first control strategy to obtain a second control strategy;

[0007] Starting and controlling the refrigerant system according to the second control strategy.

[0008] Optionally, the adjusting the control parameter in response to the compressor exhaust protection shutdown includes:

[0009] Obtaining the operating stage of the compressor before the exhaust protection shutdown;

[0010] Determining a parameter adjustment strategy according to the operating stage and adjusting the control parameter according to the parameter adjustment strategy.

[0011] Optionally, the operating stage includes a starting operation stage; if the compressor is in the starting operation stage, the parameter adjustment strategy is the first parameter adjustment strategy to adjust the control parameters according to the first parameter adjustment strategy;

[0012] The adjustment of the control parameters according to the first parameter adjustment strategy includes:

[0013] Directly adjusting the control parameters; and / or obtaining the temperature change rate of the exhaust temperature of the compressor before exhaust protection shutdown and adjusting the control parameters according to the temperature change rate.

[0014] Optionally, the refrigerant system further includes a main electronic expansion valve, an auxiliary electronic expansion valve, and a liquid injection solenoid valve;

[0015] The control parameters include at least one of the initial opening degree of the main electronic expansion valve, the initial opening degree of the auxiliary electronic expansion valve, the first starting temperature at which the liquid injection solenoid valve starts based on the exhaust temperature of the compressor under the first starting condition, and the starting water temperature at which the compressor starts based on the water temperature;

[0016] The direct adjustment of the control parameters includes: downwardly correcting the first starting temperature;

[0017] The adjustment of the control parameters according to the temperature change rate includes:

[0018] Judging whether the temperature change rate is greater than the change rate threshold;

[0019] If so, downwardly correcting the starting water temperature;

[0020] If not, upwardly correcting the initial opening degree of the main electronic expansion valve and upwardly correcting the initial opening degree of the auxiliary electronic expansion valve.

[0021] Optionally, the operating stage includes a stable operation stage; if the compressor is in the stable operation stage, the parameter adjustment strategy is the second parameter adjustment strategy to adjust the control parameters according to the second parameter adjustment strategy;

[0022] The refrigerant system further includes a liquid injection solenoid valve;

[0023] The control parameters include the target suction superheat degree of the compressor and / or the second starting temperature at which the liquid injection solenoid valve starts based on the exhaust temperature of the compressor under the second starting condition;

[0024] Adjusting the control parameter according to the second parameter adjustment strategy means directly adjusting the control parameter, and adjusting the control parameter according to the second parameter adjustment strategy includes:

[0025] Downwardly correcting the target suction superheat and downwardly correcting the second start temperature.

[0026] Optionally, the refrigerant system further includes a condenser; before adjusting the control parameter, it further includes:

[0027] Judging whether the reason for the compressor exhaust protection shutdown is insufficient refrigerant or condenser failure;

[0028] If not, then perform the adjustment of the control parameter.

[0029] Optionally, the refrigerant system further includes a main electronic expansion valve;

[0030] Judging whether the reason for the compressor exhaust protection shutdown is insufficient refrigerant or condenser failure includes:

[0031] Obtaining the exhaust pressure of the compressor before the exhaust protection shutdown, the outlet water temperature of the refrigerant system, the suction superheat of the compressor, and the opening degree of the main electronic expansion valve;

[0032] Judging whether the reason for the compressor exhaust protection shutdown is condenser failure according to the exhaust pressure and the outlet water temperature;

[0033] Judging whether the reason for the compressor exhaust protection shutdown is insufficient refrigerant according to the suction superheat and the main electronic expansion valve.

[0034] Optionally, judging whether the reason for the compressor exhaust protection shutdown is condenser failure according to the exhaust pressure and the outlet water temperature includes:

[0035] Determining the target exhaust pressure according to the outlet water temperature;

[0036] Judging whether the exhaust pressure is greater than the target exhaust pressure;

[0037] If so, determining that the reason for the compressor exhaust protection shutdown is condenser failure and sending an alarm message indicating condenser failure.

[0038] Optionally, judging whether the reason for the compressor exhaust protection shutdown is insufficient refrigerant according to the suction superheat and the main electronic expansion valve includes:

[0039] Judging whether the suction superheat is greater than the preset superheat, and judging whether the opening degree of the main electronic expansion valve is greater than or equal to the preset opening value;

[0040] If the suction superheat degree is greater than the preset superheat degree, and the opening degree of the main electronic expansion valve is greater than or equal to the preset opening degree value, it is determined that the reason for the compressor exhaust protection shutdown is insufficient refrigerant, and an alarm message indicating insufficient refrigerant is sent.

[0041] Optionally, the refrigerant system further includes a main electronic expansion valve, an auxiliary electronic expansion valve, and a liquid injection solenoid valve;

[0042] Starting and controlling the refrigerant system according to the first control strategy includes:

[0043] Start the compressor according to the starting water temperature;

[0044] Start the main electronic expansion valve according to the initial opening degree of the main electronic expansion valve; control the opening degree of the main electronic expansion valve according to the main valve control strategy of the main electronic expansion valve;

[0045] In response to meeting the starting condition of the auxiliary electronic expansion valve, start the auxiliary electronic expansion valve according to the initial opening degree of the auxiliary electronic expansion valve; control the opening degree of the auxiliary electronic expansion valve according to the auxiliary valve control strategy of the auxiliary electronic expansion valve;

[0046] In response to meeting the starting condition of the liquid injection solenoid valve, start the liquid injection solenoid valve; in response to meeting the closing condition of the liquid injection solenoid valve, close the liquid injection solenoid valve;

[0047] Judge whether the compressor is shut down due to exhaust protection.

[0048] Optionally, obtaining the operating stage of the compressor before exhaust protection shutdown includes:

[0049] Obtain the operating duration of the compressor;

[0050] Determine the operating stage according to the operating duration of the compressor; where

[0051] The operating stage includes a starting operation stage and a stable operation stage; when the operating duration of the compressor is less than or equal to the first preset duration, it is determined that the operating stage of the compressor before exhaust protection shutdown is the starting operation stage, otherwise it is determined that the operating stage of the compressor before exhaust protection shutdown is the stable operation stage.

[0052] Optionally, controlling the opening degree of the main electronic expansion valve according to the main valve control strategy of the main electronic expansion valve includes:

[0053] Obtain the operating duration of the compressor;

[0054] When the running time of the compressor is less than or equal to the second preset time, the opening degree of the main electronic expansion valve is set to the initial opening degree of the main electronic expansion valve;

[0055] When the running time of the compressor is greater than the second preset time, the opening degree of the main electronic expansion valve is adjusted according to the suction superheat and the target suction superheat.

[0056] Optionally, the control method of the heat pump unit further includes:

[0057] Judging whether the liquid injection solenoid valve is opened, or judging whether the exhaust temperature of the compressor reaches the first temperature threshold;

[0058] If the liquid injection solenoid valve is opened, or the exhaust temperature of the compressor reaches the first temperature threshold, it is determined that the starting condition of the auxiliary electronic expansion valve is satisfied.

[0059] Optionally, the starting conditions of the liquid injection solenoid valve include a first starting condition and a second starting condition, and the closing conditions include a first closing condition and a second closing condition corresponding to the first starting condition and the second starting condition respectively; the control method further includes:

[0060] Obtaining the running time of the compressor and the exhaust temperature of the compressor;

[0061] Judging whether the exhaust temperature of the compressor reaches the first starting temperature and lasts for the first duration, and judging whether the running time of the compressor is greater than the third preset time;

[0062] If the exhaust temperature of the compressor reaches the first starting temperature and lasts for the first duration, and the running time of the compressor is less than or equal to the third preset time, it is determined that the first starting condition of the liquid injection solenoid valve is satisfied;

[0063] Judging whether the exhaust temperature of the compressor drops to the second temperature threshold and lasts for the second duration, and if so, determining that the first closing condition of the liquid injection solenoid valve is satisfied;

[0064] Judging whether the exhaust temperature of the compressor reaches the second starting temperature and lasts for the third duration, and judging whether the running time of the compressor is greater than the fourth preset time;

[0065] If the exhaust temperature of the compressor reaches the second starting temperature and lasts for the third duration, and the running time of the compressor is greater than the fourth preset time, it is determined that the second starting condition of the liquid injection solenoid valve is satisfied;

[0066] Judging whether the exhaust temperature of the compressor drops to the third temperature threshold and lasts for the fourth duration, and if so, determining that the second closing condition of the liquid injection solenoid valve is satisfied.

[0067] Optionally, starting the compressor according to the starting water temperature includes:

[0068] Obtaining the outlet water temperature of the refrigerant system;

[0069] Obtaining the water temperature set value for starting the compressor based on the water temperature;

[0070] When the outlet water temperature is less than the water temperature set value and the outlet water temperature is less than the starting water temperature, start the compressor.

[0071] Optionally, the control method of the heat pump unit further includes:

[0072] Obtaining the ambient temperature where the heat pump unit is located and the outlet water temperature of the refrigerant system;

[0073] According to the ambient temperature and the outlet water temperature, when first starting and controlling the refrigerant system according to the first control strategy, determine the initial opening degree of the main electronic expansion valve, the initial opening degree of the auxiliary electronic expansion valve, and the target suction superheat degree; and, according to the ambient temperature, determine the starting water temperature of the compressor when first starting and controlling the refrigerant system according to the first control strategy.

[0074] Optionally, adjusting the control parameters means adjusting the parameter values of the control parameters at each corresponding ambient temperature and each outlet water temperature.

[0075] Optionally, the refrigerant system further includes a condenser, an economizer, a main electronic expansion valve, an evaporator, an auxiliary electronic expansion valve, and a liquid injection solenoid valve;

[0076] The inlet of the liquid injection solenoid valve is connected between the main electronic expansion valve and the economizer, and the outlet of the liquid injection solenoid valve is connected to the gas supplement port of the compressor;

[0077] The economizer includes a first heat exchange channel and a second heat exchange channel. Both ends of the first heat exchange channel are respectively connected to the condenser and the main electronic expansion valve. One end of the second heat exchange channel is connected to the gas supplement port of the compressor, and the other end of the second heat exchange channel is connected to the outlet of the auxiliary electronic expansion valve. The inlet of the auxiliary electronic expansion valve is connected between the main electronic expansion valve and the economizer; the condenser has a water flow inlet and a water flow outlet, so that the condenser is configured to heat the water flowing through it by the refrigerant flowing through it, and enable the refrigerant system to intake water through the water flow inlet and discharge water through the water flow outlet.

[0078] The present invention also provides a computer program product, including a computer program which, when executed by a processor, implements the steps of any one of the above control methods of the heat pump unit.

[0079] The present invention also provides a heat pump unit, which includes a refrigerant system, a processor, a memory, and a computer program stored on the memory. The processor executes the computer program to implement the steps of any one of the above control methods of the heat pump unit.

[0080] In the heat pump unit, the control method of the heat pump unit, and the computer program product of the present invention, because there is a first control strategy and the first control strategy is adjusted based on whether compressor exhaust protection shutdown occurs, the adjusted control strategy reduces the probability of exhaust protection shutdown again, that is, by operating the adjusted control strategy, exhaust protection shutdown is avoided as much as possible, so as to avoid the situation that the heat pump unit is locked due to consecutive multiple exhaust protection shutdowns as much as possible, ensure the normal operation of the unit, and further improve the operation duration of the heat pump unit. The heat pump unit and its control method of the present invention can prevent the occurrence of the locking problem caused by controlling multiple starts according to the same control strategy, ensure the normal operation of the unit for a long time, and further improve the operation duration of the heat pump unit.

[0081] Furthermore, in the heat pump unit, the control method of the heat pump unit, and the computer program product of the present invention, for the exhaust protection shutdown generated in different operation stages, different adjustment strategies are adopted to adjust the current control strategy, so that the adjustment of the control strategy is more adaptable and more timely, and further the probability of exhaust protection shutdown again is lower.

[0082] Therefore, according to the following detailed description of the specific embodiments of the present invention in conjunction with the drawings, those skilled in the art will more clearly understand the above and other objects, advantages, and features of the present invention. Description of the Drawings

[0083] Some specific embodiments of the present invention will be described in detail hereinafter with reference to the drawings in an exemplary and non-limiting manner. The same reference numerals in the drawings denote the same or similar components or parts. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0084] Figure 1 is a schematic structural diagram of a heat pump unit according to an embodiment of the present invention;

[0085] Figure 2 is a schematic flow chart of a control method of a heat pump unit according to an embodiment of the present invention;

[0086] Figure 3 is a schematic partial flow chart of a control method according to an embodiment of the present invention;

[0087] Figure 4 is a schematic flowchart of a control method according to an embodiment of the present invention;

[0088] Figure 5 is a schematic block diagram of a heat pump unit according to an embodiment of the present invention;

[0089] Figure 6 is a schematic block diagram of a computer program product according to an embodiment of the present invention. Detailed implementation manners

[0090] Next, with reference to Figures 1 to 6 a heat pump unit, a control method of the heat pump unit, and a computer program product according to an embodiment of the present invention will be described.

[0091] Figure 1 is a schematic structural diagram of a heat pump unit according to an embodiment of the present invention. As Figure 1 shown, an embodiment of the present invention provides a heat pump unit, which includes a refrigerant system for making hot water and a heat exchange water circuit. The refrigerant system includes a compressor 31, a condenser 32, an economizer 33, a main electronic expansion valve 34, an evaporator 35, an auxiliary electronic expansion valve 38, and a liquid injection solenoid valve 36. The inlet of the liquid injection solenoid valve 36 is connected between the main electronic expansion valve 34 and the economizer 33, and the outlet of the liquid injection solenoid valve 36 is connected to the gas supplement port of the compressor 31. A capillary throttling device 37 and / or a heat exchanger, etc. may be provided between the outlet of the liquid injection solenoid valve 36 and the gas supplement port of the compressor 31.

[0092] The economizer 33 includes a first heat exchange channel 331 and a second heat exchange channel 332. The two ends of the first heat exchange channel 331 are connected to the condenser 32 and the main electronic expansion valve 34. The first end of the second heat exchange channel 332 is connected to the gas supplement port of the compressor 31, and the second end of the second heat exchange channel 332 is connected to the outlet of the auxiliary electronic expansion valve 38. The inlet of the auxiliary electronic expansion valve 38 is connected between the main electronic expansion valve 34 and the economizer 33. The condenser 32 has a water flow inlet 321 and a water flow outlet 322, so that the refrigerant system discharges water through the water flow outlet 322. A heat exchange pipeline 39 is connected between the water flow inlet 321 and the water flow outlet 322. The condenser 32 is configured to heat the water flowing through it by using the refrigerant flowing through it. The settings of the liquid injection solenoid valve 36, the economizer 33, and the auxiliary electronic expansion valve 38 enable the heat pump unit to effectively adjust the exhaust temperature of the compressor 31 even when starting under the condition of high water temperature.

[0093] It should be noted that the present invention does not impose any restrictions on the specific structures of the condenser 32 and the evaporator 35, nor on the specific structures and models of the main electronic expansion valve 34, the auxiliary electronic expansion valve 38, and the liquid injection solenoid valve 36. The condenser 32 and the evaporator 35 can be plate heat exchangers or shell-and-tube heat exchangers. The main electronic expansion valve 34 and the auxiliary electronic expansion valve 38 can be direct-acting electronic expansion valves or step-down electronic expansion valves. These are not restrictive, and those skilled in the art can set them according to actual situations. In addition, it should be noted that the present invention does not impose any restrictions on the specific structure of the heat pump unit, and those skilled in the art can set it according to actual usage requirements.

[0094] The heat pump unit further includes a temperature sensor and a processor. The temperature sensor is used to obtain the exhaust temperature of the compressor 31, the inlet and outlet temperatures of the condenser 32, and the ambient temperature, etc. Those skilled in the art can understand that the present invention does not impose any restrictions on the specific structure, installation position, and number of the temperature sensors, and those skilled in the art can set them according to actual situations. The processor can control the opening degrees of the main electronic expansion valve 34, the auxiliary electronic expansion valve 38, and the liquid injection solenoid valve 36, and control the on-off state of the compressor 31, etc. These are not restrictive. Those skilled in the art can understand that the present invention does not impose any restrictions on the specific structure and model of the processor, and the processor can be either the original processor of the heat pump unit or a processor separately set to execute the control method of the present invention. Those skilled in the art can set the structure and model of the processor according to actual usage requirements.

[0095] Figure 2 is a schematic flowchart of a control method for a heat pump unit according to an embodiment of the present invention. As Figure 2 shown, the embodiment of the present invention also provides a control method for a heat pump unit, including:

[0096] Step S100: Start and control the refrigerant system according to a first control strategy, and the first control strategy has at least one control parameter.

[0097] Step S200: In response to the compressor 31 exhausting and protecting and shutting down, adjust the control parameter to update the first control strategy to obtain a second control strategy.

[0098] Step S300: Start and control the refrigerant system according to the second control strategy.

[0099] In the embodiment of the present invention, the heat pump unit has a first control strategy for controlling the operation of the refrigerant system. The first control strategy can make the refrigerant system operate so that the temperature of the water outlet 322 of the refrigerant system reaches a preset value to meet user needs, and / or can make the heat pump unit not to be shut down for protection as much as possible, and / or can make the heat pump unit defrost, etc. In other words, the first control strategy can be used for part or all of the operation strategies of the refrigerant system.

[0100] Further, in most cases, when the refrigerant system operates according to the first control strategy, the exhaust temperature of the compressor 31 will not reach the preset temperature, that is, the probability of the heat pump unit shutting down for protection is relatively low. However, when the refrigerant system operates according to the first control strategy and the compressor 31 shuts down for exhaust protection, it is still relatively easy for the compressor 31 to shut down for exhaust protection if it continues to work under the current working conditions. In other words, the probability of the compressor 31 shutting down for exhaust protection continuously at this time is relatively high, and the probability of causing the heat pump unit to lock is relatively high. Based on this, the embodiment of the present invention can adjust the control parameters of the first control strategy so that the first control strategy can be changed to the second control strategy, and after the compressor 31 shuts down for exhaust protection is released, the refrigerant system is controlled according to the second control strategy.

[0101] The second control strategy is to modify the first control strategy when the compressor 31 shuts down for exhaust protection under the current operating conditions according to the first control strategy, so as to adapt to the current operating conditions, reduce the probability of the compressor 31 shutting down for exhaust protection, and further reduce the probability of the heat pump unit locking, so as to make the heat pump unit run as long as possible.

[0102] Therefore, in the control method of the heat pump unit of the embodiment of the present invention, because there is a first control strategy, and the first control strategy is adjusted based on whether the compressor 31 has been shut down for exhaust protection, the adjusted control strategy reduces the probability of another exhaust protection shutdown, that is, by running the adjusted control strategy, the exhaust protection shutdown is avoided as much as possible, so as to avoid the situation where the heat pump unit is locked due to multiple consecutive exhaust protection shutdowns as much as possible, to ensure the normal operation of the unit, and thus to increase the operating time of the heat pump unit. The heat pump unit and the control method thereof of the present invention can prevent the occurrence of locking problems caused by multiple starts according to the same control strategy, ensure the normal operation of the unit for a long time, and thus to increase the operating time of the heat pump unit. In other words, the embodiment of the present invention can appropriately adjust some control parameters, which can avoid the occurrence of the exhaust protection shutdown failure of the compressor 31, and prevent the air source and other heat pump units from being locked after continuous exhaust protection, resulting in the problem that the heat pump unit cannot operate normally.

[0103] In some embodiments of the present invention, the second control strategy can also be said to be a new first control strategy. That is to say, when the second control strategy is in control and the compressor 31 also experiences exhaust protection shutdown, the second control strategy needs to be adjusted. That is, the adjustment of the control strategy can be carried out multiple times, not just once, which can further reduce the probability of the heat pump unit being locked, and make the operation time of the heat pump unit as long as possible.

[0104] In some embodiments of the present invention, such as Figure 3 and Figure 4 shown, in response to the exhaust protection shutdown of the compressor 31, the control parameters are adjusted, including:

[0105] Step S210: Obtain the operating stage of the compressor 31 before the exhaust protection shutdown.

[0106] Step S220: Determine the parameter adjustment strategy according to the operating stage, and adjust the control parameters according to the parameter adjustment strategy.

[0107] In different operating stages of the compressor 31, the local control strategies are different. For the exhaust protection shutdowns occurring in different operating stages, different adjustment strategies are used to adjust the current control strategy, which can also be said to be a segmented adjustment of the first control strategy. In this way, the original first control strategy can be ensured as much as possible, the adjustment range of the first control strategy is relatively small, and it is prevented that the control strategy mutates and the heat pump unit cannot perform basic operations, ensuring the stability of the heat pump unit operation. At the same time, for the exhaust protection shutdowns occurring in different operating stages, different adjustment strategies are used to adjust the current control strategy, making the adjustment of the control strategy more adaptable and more timely, and thus reducing the probability of the exhaust protection shutdown occurring again.

[0108] For example, the operating stage usually includes the start-up operating stage and the stable operating stage. Specifically, if the compressor 31 is in the start-up operating stage, the parameter adjustment strategy is the first parameter adjustment strategy to execute step S221 and adjust the control parameters according to the first parameter adjustment strategy. If the compressor 31 is in the stable operating stage, the parameter adjustment strategy is the second parameter adjustment strategy to execute step S222 and adjust the control parameters according to the second parameter adjustment strategy.

[0109] In some embodiments of the present invention, adjusting the control parameters according to the first parameter adjustment strategy includes: directly adjusting the control parameters; and / or obtaining the temperature change rate of the exhaust temperature of the compressor 31 before exhaust protection shutdown, and adjusting the control parameters according to the temperature change rate. Obtaining the temperature change rate of the exhaust temperature of the compressor 31 before exhaust protection shutdown may include: continuously detecting and recording the exhaust temperature of the compressor 31. When the compressor 31 shuts down due to exhaust protection, these recorded exhaust temperatures can be called to ensure the operation of the control method of the heat pump unit.

[0110] In the startup operation stage, the rotational speed of the compressor 31 changes relatively quickly and significantly, and the corresponding change in the exhaust temperature is also relatively fast and significant. Based on the temperature change rate of the exhaust temperature, it is more adaptable to the operating characteristics of the startup operation stage. Adjusting the control strategy based on the temperature change rate of the exhaust temperature enables the smooth transition through the startup operation stage when controlling according to the second control strategy, and then running to the subsequent stable operation stage to prevent shutdown immediately after startup again. If the compressor 31 shuts down immediately after startup, the impact on the compressor 31 is relatively large, and the compressor 31 is prone to damage. The control method of the heat pump unit of the present invention can prevent the compressor 31 from shutting down immediately after startup and can protect the compressor 31. Of course, in this embodiment, for some control parameters, especially those affecting the exhaust temperature, such as the startup temperature of the liquid injection solenoid valve 36 under the first startup condition, the control parameter can be directly adjusted.

[0111] Specifically, the control parameters include at least one of the initial opening degree of the main electronic expansion valve 34, the initial opening degree of the auxiliary electronic expansion valve 38, the first startup temperature at which the liquid injection solenoid valve 36 starts based on the exhaust temperature of the compressor 31 under the first startup condition, and the startup water temperature at which the compressor 31 starts based on the water temperature. The first startup temperature at which the liquid injection solenoid valve 36 starts based on the exhaust temperature of the compressor 31 under the first startup condition means that it is necessary to detect the exhaust temperature of the compressor 31. When the exhaust temperature of the compressor 31 and the first startup temperature satisfy a preset relationship, the liquid injection solenoid valve 36 can be started, or the liquid injection solenoid valve 36 can be started in combination with other conditions. For the startup water temperature at which the compressor 31 starts based on the water temperature, it is necessary to detect the inlet water temperature or the outlet water temperature of the condenser 32. When the inlet water temperature or the outlet water temperature and the startup water temperature satisfy a preset relationship, the compressor 31 can be started, or the compressor 31 can be started in combination with other conditions. The control of these several control parameters is beneficial for the compressor 31 to pass through the startup operation stage.

[0112] Further, the specific adjustment of the control parameter is as follows: downward correction of the first start-up temperature. In this embodiment, it is necessary to downward correct the first start-up temperature of the liquid injection solenoid valve 36 under the first start-up condition, which can supply air to the compressor 31 more timely. The air supply process reduces the exhaust temperature of the compressor 31, can prevent the compressor 31 from shutting down due to exhaust protection, and also helps to reduce the heat load of the compressor 31 and improve its operating efficiency.

[0113] Adjusting the control parameter according to the temperature change rate includes:

[0114] Judging whether the temperature change rate is greater than the change rate threshold.

[0115] If so, downward correct the start-up water temperature of the compressor 31. If not, upward correct the initial opening degree of the main electronic expansion valve 34 and upward correct the initial opening degree of the auxiliary electronic expansion valve 38.

[0116] In the embodiment of the present invention, the temperature change rate is the ratio of the difference between the last two detected exhaust temperatures to the detection time interval. Optionally, the temperature change rate can be calculated according to the last detected preset number of exhaust temperatures and the detection time, reflecting the speed of the increase in the exhaust temperature.

[0117] If the temperature change rate is relatively large, it means that the compressor 31 needs to discharge refrigerant with a higher temperature to be used for hot water heating. At this time, reducing the water temperature at the start of the compressor 31, that is, the initial water temperature is relatively low, the temperature requirement for the refrigerant in the condenser 32 will be reduced, then the exhaust temperature of the compressor 31 will be reduced, and the means to prevent exhaust protection will be more effective. At this time, the refrigerant system can heat water, and the probability of exhaust protection is greatly reduced. That is to say, this embodiment prevents the exhaust protection shutdown by changing the working condition of the refrigerant system and reducing the initial requirement for the start of the compressor 31. If the temperature change rate is relatively small and the exhaust protection shutdown occurs at the same time, it means that the refrigerant in the condenser 32 cannot flow out in time, resulting in too high exhaust temperature and causing the exhaust protection shutdown. Therefore, at the next start-up, the refrigerant in the condenser 32 can flow out quickly, reducing the impact on the exhaust temperature of the compressor 31, and thus preventing the exhaust protection shutdown, that is, preventing the exhaust protection by increasing the opening degree of the electronic expansion valve is more gentle. Therefore, in this embodiment of the present invention, by effectively adjusting the appropriate control parameter, it can significantly reduce the probability of the exhaust protection shutdown of the refrigerant system during the start-up and operation stage of the compressor 31, and enable the compressor 31 to safely enter the stable operation stage.

[0118] In some embodiments of the present invention, the control parameters include: the target suction superheat of the compressor 31 and / or the second starting temperature at which the liquid injection solenoid valve 36 starts based on the exhaust temperature of the compressor 31 under the second starting condition. Adjusting the control parameters according to the second parameter adjustment strategy may directly adjust the control parameters, specifically including: downwardly correcting the second starting temperature and downwardly correcting the target suction superheat.

[0119] In this embodiment, it is necessary to downwardly correct the second starting temperature of the liquid injection solenoid valve 36 under the second starting condition, which can replenish gas to the compressor 31 more timely. The gas replenishment process reduces the exhaust temperature of the compressor 31, prevents the compressor 31 from shutting down due to exhaust protection, and also helps to reduce the heat load of the compressor 31 and improve its operating efficiency.

[0120] The main function of the suction superheat is to prevent liquid refrigerant from entering the compressor 31, resulting in wet stroke and potential liquid slugging damage. The suction superheat is also closely related to the heating effect of the refrigerant system. Controlling the refrigerant system based on the suction superheat is an efficient control strategy for controlling the compressor 31 and the refrigerant system during the stable operation stage. When the exhaust protection shutdown occurs, it indicates that the suction superheat is too high under this working condition. Although a too high suction superheat can prevent liquid refrigerant from entering the compressor 31, it will cause a high suction temperature, a large suction volume, an increased load of the compressor 31, a large power consumption and a large current, which in turn promotes an excessive exhaust temperature, resulting in overload and overheat of the compressor 31, and then the exhaust protection shutdown occurs. Therefore, when it is in the stable operation stage again, the target suction superheat can be reduced so that the suction superheat is controlled within a suitable range under the current working condition, which can optimize the hot water heating effect of the refrigerant system and improve the energy efficiency ratio.

[0121] In some embodiments of the present invention, as Figure 4 shown, before adjusting the control parameters, it further includes:

[0122] Step S260, determining whether the reason for the exhaust protection shutdown of the compressor 31 is insufficient refrigerant or a failure of the condenser 32.

[0123] If not, the control parameters are adjusted. If so, the corresponding alarm information is issued.

[0124] In the embodiments of the present invention, the compressor 31 exhausting protection shutdown may also be caused by other reasons. If it is caused by other reasons, it is meaningless to adjust the first control strategy. Therefore, before judging whether to correct the first control strategy due to the compressor 31 exhausting protection shutdown, it can be first judged whether it is caused by other reasons. Especially when the compressor 31 exhausts protection shutdown occurs during the stable operation stage of the compressor 31, it must be judged whether it is caused by other reasons. The influence of insufficient refrigerant and the condenser 32 failure on the exhaust temperature of the compressor 31 is relatively obvious. When the refrigerant is insufficient or the condenser 32 fails, the exhaust temperature of the compressor 31 is easily increased to the degree that causes the exhaust protection shutdown. Therefore, in this embodiment, it can be first judged whether these two reasons cause the compressor 31 to exhaust protection shutdown, so as to prevent the compressor 31 exhaust protection shutdown caused by other faults from not being detected, directly adjusting the first control strategy, and then controlling according to the second control strategy, accelerating the damage to the compressor 31 and the refrigerant system, which is not worth the loss. That is to say, the exhaust temperature of the compressor 31 is affected by the opening degree of the main electronic expansion valve 34, the opening degree of the auxiliary electronic expansion valve 38, the ambient temperature, the outlet water temperature, the heat exchange effect of the condenser 32, etc., and the refrigerant filling amount. Moreover, the exhaust temperature protection generally appears in the cases of starting at low ambient temperature and high water temperature, operating at high water temperature, poor heat exchange of the heat exchanger, and less refrigerant filling amount. Therefore, in the embodiments of the present invention, some faults affecting the exhaust temperature of the compressor 31 can be excluded to ensure the safety of the components in the heat pump assembly, and to prevent the compressor 31 from exhausting protection shutdown as much as possible under the condition of component safety.

[0125] In some embodiments of the present invention, judging whether the reason for the compressor 31 exhausting protection shutdown is insufficient refrigerant or the condenser 32 failure includes:

[0126] Obtain the exhaust pressure of the compressor 31 before the exhaust protection shutdown, the outlet water temperature of the refrigerant system, the suction superheat of the compressor 31, and the opening degree of the main electronic expansion valve 34.

[0127] Judge whether the reason for the compressor 31 exhausting protection shutdown is the condenser 32 failure according to the exhaust pressure and the outlet water temperature. By combining the exhaust pressure and the outlet water temperature, the outlet water temperature and the exhaust pressure are corresponding in the case of the condenser 32 not failing. Since the exhaust temperature causes the compressor 31 to protect shutdown, but the corresponding exhaust pressure and the outlet water temperature do not match, this indicates that it is caused by the condenser 32 failure. Therefore, this strategy can accurately judge whether the condenser 32 failure has occurred.

[0128] Judge whether the reason for the compressor 31 to stop due to exhaust protection is insufficient refrigerant according to the suction superheat and the main electronic expansion valve 34. When the refrigerant in the system is insufficient, the circulation amount of the refrigerant decreases, resulting in a decrease in the heating efficiency. To maintain the same heating effect, the compressor 31 needs to work harder, thereby increasing its load, that is, the compressor 31 needs longer time and higher power to compress the refrigerant to reach the required temperature and pressure. This high-load working state will cause the compressor 31 to generate more heat. Due to the increase in the working intensity of the compressor 31 and the ineffective dissipation of heat, the exhaust temperature of the compressor 31 will increase significantly. Therefore, this strategy can accurately judge whether the phenomenon of insufficient refrigerant occurs.

[0129] Specifically, in some embodiments of the present invention, judging whether the reason for the compressor 31 to stop due to exhaust protection is a condenser 32 failure according to the exhaust pressure and the water outlet temperature includes:

[0130] Determine the target exhaust pressure according to the water outlet temperature;

[0131] Judge whether the exhaust pressure is greater than the target exhaust pressure;

[0132] If so, determine that the reason for the compressor 31 to stop due to exhaust protection is a condenser 32 failure, and send an alarm message indicating a condenser 32 failure.

[0133] In some embodiments of the present invention, judging whether the reason for the compressor 31 to stop due to exhaust protection is insufficient refrigerant according to the suction superheat and the main electronic expansion valve 34 includes:

[0134] Judge whether the suction superheat is greater than the preset superheat, and judge whether the opening degree of the main electronic expansion valve 34 is greater than or equal to the preset opening degree value;

[0135] If the suction superheat is greater than the preset superheat and the opening degree of the main electronic expansion valve 34 is greater than or equal to the preset opening degree value, determine that the reason for the compressor 31 to stop due to exhaust protection is insufficient refrigerant, and send an alarm message indicating insufficient refrigerant.

[0136] In the embodiments of the present invention, the preset opening degree value can preferably be the maximum opening degree value of the main electronic expansion valve 34. Generally, when the opening degree of the main electronic expansion valve 34 is greater than or equal to the preset opening degree value, the compressor 31 basically will not stop due to exhaust protection when it runs again. Then, if the compressor 31 also stops due to exhaust protection at this time, it is caused by insufficient refrigerant, and it can accurately judge whether the phenomenon of insufficient refrigerant occurs.

[0137] In some embodiments of the present invention, as Figure 4 shown, starting and controlling the refrigerant system according to the first control strategy includes:

[0138] Step S103: Start the compressor 31 according to the starting water temperature. Start the main electronic expansion valve 34 according to its initial opening degree. Control the opening degree of the main electronic expansion valve 34 according to the main valve control strategy of the main electronic expansion valve 34.

[0139] Step S104: In response to meeting the starting condition of the auxiliary electronic expansion valve 38, start the auxiliary electronic expansion valve 38 according to its initial opening degree. Control the opening degree of the auxiliary electronic expansion valve 38 according to the auxiliary valve control strategy of the auxiliary electronic expansion valve 38.

[0140] Step S105: In response to meeting the starting condition of the liquid injection solenoid valve 36, start the liquid injection solenoid valve 36.

[0141] Step S106: In response to meeting the closing condition of the liquid injection solenoid valve 36, close the liquid injection solenoid valve 36.

[0142] Step S107: Determine whether the compressor 31 shuts down due to exhaust protection.

[0143] In the embodiment of the present invention, the opening degree of the main electronic expansion valve 34, the opening / closing / opening degree of the auxiliary electronic expansion valve 38, the opening / closing of the liquid injection solenoid valve 36, etc. can be controlled, and during the control process, it is judged whether the compressor 31 shuts down due to exhaust protection. This first control strategy can reasonably control the refrigerant system, meet the requirements such as making hot water, and can also perform self-protection to ensure the safety of the refrigerant system.

[0144] In some embodiments of the present invention, obtaining the operating stage of the compressor 31 before shutting down due to exhaust protection includes:

[0145] Obtain the operating duration of the compressor 31.

[0146] Determine the operating stage according to the operating duration of the compressor 31. Among them

[0147] The operating stage includes a starting operation stage and a stable operation stage. When the operating duration of the compressor 31 is less than or equal to the first preset duration, it is determined that the operating stage of the compressor 31 before shutting down due to exhaust protection is the starting operation stage, otherwise the operating stage of the compressor 31 before shutting down due to exhaust protection is the stable operation stage.

[0148] The operation of the compressor 31 is the most important device in the entire operation process of the refrigerant system, and the exhaust protection mainly protects the compressor 31. Since the control strategies of the compressor 31 are different in different stages, the operating duration of the compressor 31 allowed in each stage needs to be controlled. Especially in the starting operation stage, there are generally strict duration requirements. Therefore, based on the operating duration of the compressor 31, the operating stages of the compressor 31 can be accurately divided, which can better meet the operating characteristics of the compressor 31, etc., enabling the compressor 31, etc. to operate better, and at the same time making it more controllable and beneficial to prevent the compressor 31 from exhausting and shutting down for protection in each stage.

[0149] In some embodiments of the present invention, controlling the opening degree of the main electronic expansion valve 34 according to the main valve control strategy of the main electronic expansion valve 34 includes:

[0150] When the operating duration of the compressor 31 is less than or equal to the second preset duration, the opening degree of the main electronic expansion valve 34 is made the initial opening degree of the main electronic expansion valve 34.

[0151] When the operating duration of the compressor 31 is greater than the second preset duration, the opening degree of the main electronic expansion valve 34 is adjusted according to the suction superheat and the target suction superheat.

[0152] In the embodiments of the present invention, within the second preset duration, the opening degree of the main electronic expansion valve 34 is made the initial opening degree and is a constant opening degree, which is beneficial to the stable operation of the compressor 31 and ensures the smooth start of the compressor 31. As mentioned above, the main function of the suction superheat is to prevent liquid refrigerant from entering the compressor 31, resulting in wet stroke and potential liquid hammer damage. The suction superheat is also closely related to the heating effect of the refrigerant system. Controlling the refrigerant system based on the suction superheat is an efficient control strategy for controlling the compressor 31 and the refrigerant system in the stable operation stage.

[0153] Preferably, in some embodiments of the present invention, the second preset duration is equal to the first preset duration, and the first preset duration can be 3 min to 5 min, preferably 4 min. That is to say, the first control strategy may include the following process: the main electronic expansion valve 34 is opened to the initial opening degree, the fan used in conjunction with the evaporator 35 operates, the compressor 31 operates, and after the second preset duration, it enters the stable operation stage, and the main electronic expansion valve 34 is adjusted according to the suction superheat.

[0154] In some embodiments of the present invention, as Figure 4 shown, the starting conditions of the liquid injection solenoid valve 36 include a first starting condition and a second starting condition, and the closing conditions include a first closing condition and a second closing condition corresponding to the first starting condition and the second starting condition respectively. The control method of the heat pump unit further includes:

[0155] Obtain the running duration of the compressor 31 and obtain the exhaust temperature of the compressor 31.

[0156] Judge whether the exhaust temperature of the compressor 31 reaches the first starting temperature and lasts for the first duration, and judge whether the running duration of the compressor 31 is greater than the third preset duration.

[0157] If the exhaust temperature of the compressor 31 reaches the first starting temperature and lasts for the first duration, and the running duration of the compressor 31 is less than or equal to the third preset duration, it is determined that the first starting condition of the liquid injection solenoid valve 36 is satisfied.

[0158] Judge whether the exhaust temperature of the compressor 31 drops to the second temperature threshold and lasts for the first duration. If so, it is determined that the first closing condition of the liquid injection solenoid valve 36 is satisfied.

[0159] Judge whether the exhaust temperature of the compressor 31 reaches the second starting temperature and lasts for the third duration, and judge whether the running duration of the compressor 31 is greater than the fourth preset duration. The fourth preset duration is greater than or equal to the third preset duration.

[0160] If the exhaust temperature of the compressor 31 reaches the second starting temperature and lasts for the third duration, and the running duration of the compressor 31 is greater than the fourth preset duration, it is determined that the second starting condition of the liquid injection solenoid valve 36 is satisfied.

[0161] Judge whether the exhaust temperature of the compressor 31 drops to the third temperature threshold and lasts for the fourth duration. If so, it is determined that the second closing condition of the liquid injection solenoid valve 36 is satisfied.

[0162] At different running time points, that is, at different running stages, the requirements for the exhaust temperature of the compressor 31 can be inconsistent, and the requirements for the exhaust temperature that may potentially cause the compressor 31 to be protected and shut down are inconsistent. This is set considering the heating performance requirements of the compressor 31 and the heat pump assembly. Therefore, different starting strategies and corresponding closing strategies need to be adopted at different time points and different stages to improve the energy efficiency ratio of the heat pump assembly. The first duration, the second duration, the third duration, and the fourth duration can be preset values.

[0163] In some embodiments of the present invention, the third preset duration is equal to the first preset duration, and the fourth preset duration is equal to the first preset duration. That is to say, the liquid injection solenoid valve 36 has corresponding start-stop strategies in both the start-up operation stage and the stable operation stage.

[0164] In some embodiments of the present invention, the second starting temperature may be greater than or equal to the first starting temperature, the second temperature threshold is less than the first starting temperature, and may also be less than the second starting temperature. The third temperature threshold is less than the second starting temperature and may also be less than the first starting temperature. The first starting temperature is preferably 70% to 80% of the exhaust protection temperature threshold, preferably 75%. The second starting temperature is preferably 80% to 90% of the exhaust protection temperature threshold, preferably 85%. The first duration, the second duration, the third duration, and the fourth duration may all be 2.5S to 3.5S, preferably 3S.

[0165] In an embodiment of the present invention, when the compressor 31 is operating, the exhaust temperature of the compressor 31 is obtained. It should be noted that the present invention does not impose any restrictions on the specific method of obtaining the exhaust temperature. It can be obtained in real time after the compressor 31 starts, or it can be obtained after a period of time after the compressor 31 starts, which is not restrictive. By controlling the operating state of the liquid injection solenoid valve 36 through the obtained exhaust temperature of the compressor 31, the heat pump unit can effectively adjust the exhaust temperature of the compressor 31 even in the case of high water temperature, and effectively solve the problem of low heating efficiency of the heat pump unit due to high water temperature on the basis of effectively ensuring the heating capacity of the heat pump unit.

[0166] In some embodiments of the present invention, the control method of the heat pump unit further includes:

[0167] Determine whether the liquid injection solenoid valve 36 is open, or determine whether the exhaust temperature of the compressor 31 reaches the first temperature threshold.

[0168] If the liquid injection solenoid valve 36 is open, or the exhaust temperature of the compressor 31 reaches the first temperature threshold, it is determined that the starting condition of the auxiliary electronic expansion valve 38 is satisfied.

[0169] In an embodiment of the present invention, based on the relatively high exhaust temperature of the compressor 31, there is a risk of compressor 31 exhaust protection shutdown. The auxiliary electronic expansion valve 38 can be controlled to open to reduce the exhaust temperature of the compressor 31 and ensure the smooth operation of the heat pump unit. That is, by controlling the operating state of the auxiliary electronic expansion valve 38 through the obtained exhaust temperature of the compressor 31, the heat pump unit can still effectively adjust the exhaust temperature of the compressor 31 even when starting in the case of high water temperature, effectively avoiding the problem that the heat pump unit is not in the optimal operating state caused by adjusting the opening of the main electronic expansion valve 34 to control the exhaust temperature, and also avoiding the problem of affecting the normal use of users by reducing the water temperature. On the basis of effectively ensuring the heating capacity of the heat pump unit, it effectively solves the problem of low heating efficiency of the heat pump unit due to high water temperature.

[0170] In some embodiments of the present invention, the first temperature threshold is preferably 55% to 65% of the exhaust protection temperature threshold, preferably 60%.

[0171] The present invention does not impose any restrictions on the specific adjustment method of the opening degree of the auxiliary electronic expansion valve 38, as long as it can effectively ensure the smooth operation of the heat pump unit and the heating capacity. As a preferred embodiment, controlling the opening degree of the auxiliary electronic expansion valve 38 according to the auxiliary valve control strategy of the auxiliary electronic expansion valve 38 includes:

[0172] Obtaining the suction temperature and suction saturation temperature of the compressor 31;

[0173] Adjusting the opening degree of the auxiliary electronic expansion valve 38 according to the suction temperature and suction saturation temperature of the compressor 31;

[0174] When the compressor 31 shuts down, closing the auxiliary electronic expansion valve 38.

[0175] In this embodiment, if the suction temperature of the compressor 31 is close to the suction saturation temperature, the opening degree of the auxiliary electronic expansion valve 38 is controlled to increase to reduce the suction temperature of the compressor 31, and then reduce the discharge temperature; of course, this is only an exemplary description, and those skilled in the art can adjust the opening degree of the auxiliary electronic expansion valve 38 according to the actual situation based on the suction temperature and suction saturation temperature of the compressor 31.

[0176] In some embodiments of the present invention, determining whether the compressor 31 is shut down due to exhaust protection includes:

[0177] Obtaining the discharge temperature of the compressor 31 and determining whether the discharge temperature is greater than or equal to the exhaust protection temperature threshold.

[0178] If so, the compressor 31 is shut down and it is determined that the compressor 31 is shut down due to exhaust protection. By determining whether the compressor 31 is shut down due to exhaust protection, the compressor 31 can be shut down when the exhaust temperature is too high to protect the compressor 31.

[0179] In some embodiments of the present invention, as Figure 4 shown, the control method of the heat pump unit further includes:

[0180] Step S101: Obtaining the ambient temperature where the heat pump unit is located and the outlet water temperature of the refrigerant system.

[0181] Step S102: According to the ambient temperature and the outlet water temperature, determining the initial opening degree of the main electronic expansion valve 34, the initial opening degree of the auxiliary electronic expansion valve 38, and the target suction superheat degree when first starting and controlling the refrigerant system according to the first control strategy. And, according to the ambient temperature, determining the starting water temperature at which the compressor 31 starts based on the water temperature when first starting and controlling the refrigerant system according to the first control strategy.

[0182] In some embodiments of the present invention, adjusting the control parameters means adjusting the parameter values of the control parameters at each corresponding ambient temperature and each outlet water temperature. Further, each time the first start temperature or the second start temperature is corrected downward, it can be corrected by 5°C to 10°C each time. Each time the initial opening of the main electronic expansion valve 34 is corrected upward, it can be corrected by 50 to 100 each time. Each time the initial opening of the auxiliary electronic expansion valve 38 is corrected upward, it can be corrected by 50 to 100 each time, that is, the corresponding number of steps is increased on the original initial opening; preferably, the initial opening of the auxiliary electronic expansion valve 38 can be directly corrected to the maximum. Each time the target suction superheat is corrected downward, it can be corrected by 0.4°C to 0.6°C each time.

[0183] In some embodiments of the present invention, if the parameter value of the control parameter is corrected to the maximum or the minimum and no further correction is made, it is still considered that the corresponding parameter has been corrected so that the control method of the heat pump unit can continue to be executed. It can also be said that, in order to avoid the situation where correction is impossible, before correcting each control parameter, it is judged whether the parameter is at the maximum or minimum value, that is, it is judged whether each control parameter still has the possibility of correction. If it has, correction is made; if not, the current parameter value is maintained. If all parameters cannot be corrected, an alarm indicating that correction is impossible is issued after the compressor 31 stops due to exhaust protection, and further, the compressor 31 can be stopped from starting again.

[0184] In some embodiments of the present invention, starting the compressor 31 according to the starting water temperature includes:

[0185] Obtaining the outlet water temperature of the refrigerant system.

[0186] Obtaining the water temperature set value for starting the compressor 31 based on the water temperature.

[0187] When the outlet water temperature is less than the water temperature set value and the outlet water temperature is less than the starting water temperature, start the compressor 31.

[0188] In some embodiments of the present invention, the starting water temperature at which the compressor 31 starts based on the water temperature is obtained by the following formula: Two2 = a1 * Ta + b - 5; where Two2 is the starting water temperature, Ta is the ambient temperature, a1 is the first constant, and b is the second constant. Each time the starting water temperature is corrected downward, it is obtained by the following formula: Two2 = a1 * Ta + b - 5 - △Two; where Two2 is the starting water temperature, Ta is the ambient temperature, a1 is the first constant, b is the second constant, and △Two generally takes a value of 2°C to 5°C. That is to say, each time of correction, the starting water temperature can be corrected downward by 2°C to 5°C.

[0189] In some embodiments of the present invention, when starting and controlling the refrigerant system according to the first control strategy, it further includes: turning off the compressor 31 according to the outlet water temperature. Specifically, when the outlet water temperature is greater than or equal to the shutdown water temperature, the compressor 31 can be turned off. The shutdown water temperature can be determined according to the ambient temperature, and the shutdown water temperature can also be set according to user requirements. Further, the shutdown water temperature is obtained through the following formula: Two1 = a1 * Ta + b; where Two1 is the shutdown water temperature, Ta is the ambient temperature, a1 is the first constant, and b is the second constant.

[0190] In some embodiments of the present invention, there is a mapping relationship table of ambient temperature - outlet water temperature - initial opening degree of the main electronic expansion valve 34 in the heat pump unit. This mapping relationship table reflects different initial opening degrees of the main electronic expansion valve 34 required by the refrigerant system when the ambient temperature is in different temperature ranges and the outlet water temperature is in the corresponding temperature ranges. There is also a mapping relationship table of ambient temperature - outlet water temperature - target suction superheat in the heat pump unit. This mapping relationship table reflects the target suction superheat required by the refrigerant system when the ambient temperature is in different temperature ranges and the outlet water temperature is in the corresponding temperature ranges. These two mapping relationship tables can be reflected in one table, as shown in Table 1 below:

[0191] Table 1

[0192]

[0193] In Table 1, Ta is the ambient temperature; Two is the outlet water temperature; A1, A2, Sh are preset values; a1, a2, a3, a4, a5, a6 are constants. The two preset relationships in Table 1 can be obtained through means such as testing, or can also be obtained through the way of neural network learning. The initial opening degree of the main electronic expansion valve 34 is to enable the heat pump unit to enter the stable operation stage without taking a long time. The initial opening degree of the main electronic expansion valve 34 can enable the heat pump unit to quickly enter the stable state after startup, and on the basis of ensuring that the heating capacity of the heat pump unit does not change much, effectively solve the problem that the heat pump unit cannot start due to too high exhaust temperature.

[0194] In some embodiments of the present invention, there is a mapping relationship table of ambient temperature - outlet water temperature - initial opening degree of the auxiliary electronic expansion valve 38 in the heat pump unit. This mapping relationship table reflects different initial opening degrees of the auxiliary electronic expansion valve 38 required by the refrigerant system when the ambient temperature is in different temperature ranges and the outlet water temperature is in the corresponding temperature ranges. This mapping relationship table can be as shown in Table 2 below:

[0195] Table 2

[0196]

[0197] In Table 2, Ta is the ambient temperature; Two is the outlet water temperature; B1 to B20 are all preset values. The preset relationship in Table 2 can be obtained by means such as testing, or can also be obtained by means of neural network learning.

[0198] As Figure 5 shown, in the heat pump unit provided by the embodiment of the present invention, the controller 110 includes a memory 111, a processor 112, and a computer program 210 stored on the memory 111 and running on the processor 112. When the processor 112 executes the computer program 210, the steps of the control method of the heat pump unit in any one of the above embodiments or combinations of embodiments are implemented.

[0199] The controller 110 can be directly set in the heat pump unit, is wired-connected to the electrical components related to the heat pump unit, and implements the steps of the control method of the heat pump unit. The controller can also be set on a cloud server, is wired or wirelessly connected to the electrical components related to the heat pump unit, and implements the steps of the control method of the heat pump unit.

[0200] The heat pump unit can be a household air conditioner, a central air conditioner, a multi-connected air conditioner, a heat pump water heater, etc.

[0201] As Figure 6 shown, the embodiment of the present invention also provides a computer program product. The computer program product 200 includes a computer program 210. When the computer program 210 is executed by the processor 112, the steps of the control method of the heat pump unit in any one of the above are implemented.

[0202] The computer program 210 for performing the operations of the present invention may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine - related instructions, microcode, firmware instructions, state - setting data, configuration data of an integrated circuit, or source code or object code written in any combination of one or more programming languages and procedural programming languages. The computer program 210 may be executed entirely on the user's computer, partially on the user's computer, executed as a stand - alone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, to perform aspects of the present invention, an electronic circuit, including for example a programmable logic circuit, a field - programmable gate array (FPGA), or a programmable logic array (PLA), may execute computer - readable program instructions by utilizing the state information of the computer - readable program instructions to personalize the electronic circuit.

[0203] For the description of this embodiment, the computer program product 200 is a related product that includes the computer program 210.

[0204] The computer program 210 may be stored in a computer - readable storage medium.

[0205] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a definable sequence list of executable instructions for implementing logical functions, and can be specifically implemented in any computer - readable storage medium for use by an instruction - execution system, apparatus, or device (such as a computer - based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction - execution system, apparatus, or device), or used in conjunction with these instruction - execution systems, apparatus, or devices.

[0206] For the description of this embodiment, a computer-readable storage medium can be any device that can contain, store, communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable storage medium include the following: an electrical connection part (electronic device) having one or more wirings, a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable storage medium can even be paper or other suitable media on which a program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpretation, or otherwise processing it in a suitable manner if necessary, and then storing it in a computer memory.

[0207] The flowchart provided in this embodiment is not intended to indicate that the operations of the method will be executed in any specific order, or that all operations of the method are included in every case. Additionally, the method can include additional operations. Within the scope of the technical concept provided by the method of this embodiment, additional variations can be made to the above method.

[0208] There are multiple exemplary embodiments of the present invention. However, without departing from the spirit and scope of the present invention, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived based on the content disclosed in the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all these other variations or modifications.

Claims

1. A control method for a heat pump unit, characterized in that, The heat pump unit includes a refrigerant system for heating water, and the refrigerant system includes a compressor. The control method of the heat pump unit includes: Starting and controlling the refrigerant system according to a first control strategy, the first control strategy having at least one control parameter; In response to the compressor shutting down due to exhaust protection, adjusting the control parameter to update the first control strategy to obtain a second control strategy; Starting and controlling the refrigerant system according to the second control strategy.

2. The control method of the heat pump unit according to claim 1, characterized in that The adjusting the control parameter in response to the compressor shutting down due to exhaust protection includes: Obtaining the operating stage of the compressor before shutting down due to exhaust protection; Determining a parameter adjustment strategy according to the operating stage, and adjusting the control parameter according to the parameter adjustment strategy.

3. The control method of the heat pump unit according to claim 2, characterized in that The operating stage includes a starting operation stage; if the compressor is in the starting operation stage, the parameter adjustment strategy is a first parameter adjustment strategy, and the control parameter is adjusted according to the first parameter adjustment strategy; The adjusting the control parameter according to the first parameter adjustment strategy includes: Directly adjusting the control parameter; and / or obtaining the temperature change rate of the exhaust temperature of the compressor before shutting down due to exhaust protection, and adjusting the control parameter according to the temperature change rate.

4. The control method of the heat pump unit according to claim 3, characterized in that The refrigerant system further includes a main electronic expansion valve, an auxiliary electronic expansion valve, and a liquid injection solenoid valve; The control parameter includes at least one of: the initial opening degree of the main electronic expansion valve, the initial opening degree of the auxiliary electronic expansion valve, the first starting temperature at which the liquid injection solenoid valve starts based on the exhaust temperature of the compressor under a first starting condition, and the starting water temperature at which the compressor starts based on the water temperature; The directly adjusting the control parameter includes: downwardly correcting the first starting temperature; The adjusting the control parameter according to the temperature change rate includes: Judging whether the temperature change rate is greater than a change rate threshold; If so, downwardly correcting the starting water temperature; If not, upwardly correcting the initial opening degree of the main electronic expansion valve and upwardly correcting the initial opening degree of the auxiliary electronic expansion valve.

5. The control method of the heat pump unit according to claim 2, characterized in that The operating stage includes a stable operation stage; if the compressor is in the stable operation stage, the parameter adjustment strategy is a second parameter adjustment strategy, and the control parameter is adjusted according to the second parameter adjustment strategy; The refrigerant system further includes a liquid injection solenoid valve; The control parameter includes: the target suction superheat degree of the compressor and / or the second starting temperature at which the liquid injection solenoid valve starts based on the exhaust temperature of the compressor under a second starting condition; The adjustment of the control parameter according to the second-parameter adjustment strategy is to directly adjust the control parameter, and the adjustment of the control parameter according to the second-parameter adjustment strategy includes: Downwardly correcting the target suction superheat degree and downwardly correcting the second start temperature.

6. The control method of the heat pump unit according to claim 1, wherein The refrigerant system further includes a condenser; before adjusting the control parameter, it further includes: Judging whether the reason for the compressor exhaust protection shutdown is insufficient refrigerant or condenser failure; If not, then perform the adjustment of the control parameter.

7. The control method of the heat pump unit according to claim 6, wherein The refrigerant system further includes a main electronic expansion valve; Judging whether the reason for the compressor exhaust protection shutdown is insufficient refrigerant or condenser failure includes: Obtaining the exhaust pressure of the compressor before exhaust protection shutdown, the water outlet temperature of the refrigerant system, the suction superheat degree of the compressor, and the opening degree of the main electronic expansion valve; Judging whether the reason for the compressor exhaust protection shutdown is condenser failure according to the exhaust pressure and the water outlet temperature; Judging whether the reason for the compressor exhaust protection shutdown is insufficient refrigerant according to the suction superheat degree and the main electronic expansion valve.

8. The control method of the heat pump unit according to claim 7, wherein The judging whether the reason for the compressor exhaust protection shutdown is condenser failure according to the exhaust pressure and the water outlet temperature includes: Determining the target exhaust pressure according to the water outlet temperature; Judging whether the exhaust pressure is greater than the target exhaust pressure; If so, determining that the reason for the compressor exhaust protection shutdown is condenser failure and sending out an alarm message indicating condenser failure; The judging whether the reason for the compressor exhaust protection shutdown is insufficient refrigerant according to the suction superheat degree and the main electronic expansion valve includes: Judging whether the suction superheat degree is greater than a preset superheat degree and judging whether the opening degree of the main electronic expansion valve is greater than or equal to a preset opening degree value; If the suction superheat degree is greater than the preset superheat degree and the opening degree of the main electronic expansion valve is greater than or equal to the preset opening degree value, then determining that the reason for the compressor exhaust protection shutdown is insufficient refrigerant and sending out an alarm message indicating insufficient refrigerant.

9. The control method of the heat pump unit according to claim 2, wherein The obtaining of the operating stage of the compressor before exhaust protection shutdown includes: Obtaining the operating duration of the compressor; Determining the operating stage according to the operating duration of the compressor; wherein The operating stage includes a start-up operating stage and a stable operating stage; when the operating duration of the compressor is less than or equal to a first preset duration, determining that the operating stage of the compressor before exhaust protection shutdown is the start-up operating stage, otherwise the operating stage of the compressor before exhaust protection shutdown is the stable operating stage.

10. The control method of the heat pump unit according to claim 2, wherein The refrigerant system further includes a main electronic expansion valve, an auxiliary electronic expansion valve, and a liquid injection solenoid valve; The starting and controlling of the refrigerant system according to the first control strategy includes: Starting the compressor according to the starting water temperature; Starting the main electronic expansion valve according to the initial opening degree of the main electronic expansion valve; controlling the opening degree of the main electronic expansion valve according to the main valve control strategy of the main electronic expansion valve; In response to meeting the starting condition of the auxiliary electronic expansion valve, starting the auxiliary electronic expansion valve according to the initial opening degree of the auxiliary electronic expansion valve; In response to meeting the starting condition of the liquid injection solenoid valve, starting the liquid injection solenoid valve; in response to meeting the closing condition of the liquid injection solenoid valve, closing the liquid injection solenoid valve; Judging whether the compressor is protected from exhaust shutdown.

11. The control method of the heat pump unit according to claim 10, wherein The controlling the opening degree of the main electronic expansion valve according to the main valve control strategy of the main electronic expansion valve includes: Obtaining the running duration of the compressor; When the running duration of the compressor is less than or equal to a second preset duration, making the opening degree of the main electronic expansion valve be the initial opening degree of the main electronic expansion valve; When the running duration of the compressor is greater than the second preset duration, adjusting the opening degree of the main electronic expansion valve according to the suction superheat degree and the target suction superheat degree.

12. The control method of the heat pump unit according to claim 10, characterized in that, It further includes: Judging whether the liquid injection solenoid valve is opened, or judging whether the exhaust temperature of the compressor reaches a first temperature threshold; If the liquid injection solenoid valve is opened, or the exhaust temperature of the compressor reaches the first temperature threshold, it is determined that the starting condition of the auxiliary electronic expansion valve is met.

13. The control method of the heat pump unit according to claim 10, wherein The starting conditions of the liquid injection solenoid valve include a first starting condition and a second starting condition, and the closing conditions include a first closing condition and a second closing condition corresponding to the first starting condition and the second starting condition respectively; the control method further includes: Obtaining the running duration of the compressor and obtaining the exhaust temperature of the compressor; Judging whether the exhaust temperature of the compressor reaches a first starting temperature and lasts for a first duration, and judging whether the running duration of the compressor is greater than a third preset duration; If the exhaust temperature of the compressor reaches the first starting temperature and lasts for the first duration, and the running duration of the compressor is less than or equal to the third preset duration, it is determined that the first starting condition of the liquid injection solenoid valve is met; Judging whether the exhaust temperature of the compressor drops to a second temperature threshold and lasts for a second duration, if so, it is determined that the first closing condition of the liquid injection solenoid valve is met; Judging whether the exhaust temperature of the compressor reaches a second starting temperature and lasts for a third duration, and judging whether the running duration of the compressor is greater than a fourth preset duration; the fourth preset duration is greater than or equal to the third preset duration; If the exhaust temperature of the compressor reaches the second starting temperature and lasts for the third duration, and the running duration of the compressor is greater than the fourth preset duration, it is determined that the second starting condition of the liquid injection solenoid valve is met; Determine whether the exhaust temperature of the compressor drops to a third temperature threshold and lasts for a fourth duration. If so, it is determined that the second closing condition of the liquid injection solenoid valve is satisfied.

14. The control method of the heat pump unit according to claim 10, characterized in that, It further includes: Obtain the ambient temperature of the heat pump unit and the outlet water temperature of the refrigerant system; According to the ambient temperature and the outlet water temperature, determine the initial opening degree of the main electronic expansion valve, the initial opening degree of the auxiliary electronic expansion valve, and the target suction superheat degree when the refrigerant system is first started and controlled according to the first control strategy; and, according to the ambient temperature, determine the starting water temperature at which the compressor starts based on the water temperature when the refrigerant system is first started and controlled according to the first control strategy; The adjustment of the control parameters is to adjust the parameter values of the control parameters at each corresponding ambient temperature and each outlet water temperature.

15. The control method of the heat pump unit according to claim 10, wherein: The refrigerant system further includes a condenser, an economizer, a main electronic expansion valve, an evaporator, an auxiliary electronic expansion valve, and a liquid injection solenoid valve; The inlet of the liquid injection solenoid valve is connected between the main electronic expansion valve and the economizer, and the outlet of the liquid injection solenoid valve is connected to the gas replenishing port of the compressor; The economizer includes a first heat exchange channel and a second heat exchange channel. The two ends of the first heat exchange channel are respectively connected to the condenser and the main electronic expansion valve. One end of the second heat exchange channel is connected to the gas replenishing port of the compressor, and the other end of the second heat exchange channel is connected to the outlet of the auxiliary electronic expansion valve. The inlet of the auxiliary electronic expansion valve is connected between the main electronic expansion valve and the economizer; the condenser has a water flow inlet and a water flow outlet, so that the condenser is configured to heat the water flowing through it by the refrigerant flowing through it, and enable the refrigerant system to intake water through the water flow inlet and discharge water through the water flow outlet.

16. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it realizes the steps of the control method of the heat pump unit according to any one of claims 1 to 15.

17. A heat pump unit, characterized in that, It includes a refrigerant system, a processor, a memory, and a computer program stored on the memory. The processor executes the computer program to realize the steps of the control method of the heat pump unit according to any one of claims 1 to 15.

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