Air source heat pump water heater control method

Abstract

The invention discloses an air source heat pump water heater control method, and relates to the technical field of air source heat pumps. According to the technical scheme, the air conditioner is characterized by comprising a compressor, a copper pipe, a four-way reversing valve, a plate type heat exchanger, a throttling electronic expansion valve, a fin type heat exchanger, a cooling fan, a circulating water pump and a heat preservation circulating water tank; the suction temperature sensor is used for monitoring the suction temperature of a low-temperature and low-pressure refrigerant entering the compressor, and the exhaust temperature sensor is used for monitoring the exhaust temperature of a high-temperature and high-pressure refrigerant gas exhausted after the high-temperature and high-pressure refrigerant gas is compressed by the compressor; the method has the advantages that the refrigerant flow is adjusted through a superheat degree control mode and an external temperature control method of the electronic expansion valve, the refrigerant flow can be accurately matched according to factors such as the system operation state and the external environment temperature through the adjusting mode, the heating or refrigerating performance of the system is improved, and meanwhile energy waste is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of air source heat pumps, and more specifically, to a control method for an air source heat pump water heater. Background Art

[0002] With the improvement of people's requirements for the quality of life and the enhancement of energy conservation and environmental protection awareness, air source heat pump water heaters, as a kind of efficient and energy-saving hot water supply equipment, have been widely used in the fields of home, commerce and industry. In the traditional air source heat pump water heater technology, there are some problems that need to be solved urgently. In terms of heat exchange, the heat exchanger structures and performances adopted by some equipment are not ideal enough, resulting in low heat exchange efficiency between the refrigerant and the circulating water, and between the refrigerant and the external air, thus affecting the hot water production speed and the overall heating performance of the system.

[0003] In terms of operation mode switching, many air source heat pump water heaters lack an intelligent operating condition judgment mechanism and cannot flexibly and accurately switch between the refrigeration mode and the heating mode according to parameters such as the actual return water temperature, and cannot fully meet the diverse needs of users under different environmental temperatures.

[0004] The adjustment methods of the existing air source heat pump water heater control methods are relatively rough and cannot be finely adjusted according to factors such as the real-time operating state of the system and the external environmental temperature. This will not only lead to poor heating or refrigeration effects of the system, but also cause waste of energy and increase the operating cost. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a control method for an air source heat pump water heater.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A control method for an air source heat pump water heater, including a compressor, a copper pipe, a four-way reversing valve, a plate heat exchanger, a throttling electronic expansion valve, a finned heat exchanger, a cooling fan, a circulating water pump, and a heat preservation circulating water tank:

[0008] The compressor is provided with a suction temperature sensor and a discharge temperature sensor. The suction temperature sensor is used to monitor the suction temperature of the low-temperature and low-pressure refrigerant entering the compressor, and the discharge temperature sensor is used to monitor the discharge temperature of the high-temperature and high-pressure refrigerant gas discharged after being compressed by the compressor;

[0009] The plate heat exchanger is connected to the compressor through a copper pipe, and the high-temperature and high-pressure refrigerant gas generated by the compressor exchanges heat with the circulating water through the plate heat exchanger;

[0010] The throttling electronic expansion valve is connected to the finned heat exchanger through a copper pipe. The throttling electronic expansion valve throttles and reduces the pressure of the high-temperature and high-pressure refrigerant liquid, turning it into a low-temperature and low-pressure gas-liquid mixture. The other end of the throttling electronic expansion valve is connected to the plate heat exchanger;

[0011] The interfaces of the four-way reversing valve are respectively connected to the throttling electronic expansion valve, the finned heat exchanger, the plate heat exchanger and the compressor. The four-way reversing valve changes the flow direction of the refrigerant in the refrigeration and heating cycles by changing the position of the internal valve core;

[0012] The finned heat exchanger is connected to the interface of the four-way reversing valve. The low-temperature and low-pressure gas-liquid mixed refrigerant absorbs the heat of the outside air in the finned heat exchanger and transfers and releases it into the circulating water together with the heat work done by the compressor. The finned heat exchanger is provided with an electric de-icing heater to prevent frosting on the fin surface; The cooling fan is arranged near the finned heat exchanger;

[0013] The water inlet of the circulating water pump is connected to the circulating water outlet of the plate heat exchanger. The circulating water pump transports the cooled circulating water to the water return port of the heat preservation circulating water tank to provide power for the flow of the circulating water;

[0014] Regarding the refrigerant circuit circulation, when making hot water and circulating, the air source heat pump water heater is in the outdoor-side heating working environment temperature. The low-temperature and low-pressure gas refrigerant is compressed into a high-temperature and high-pressure refrigerant gas by the compressor. The high-temperature and high-pressure refrigerant gas enters the plate heat exchanger through the copper pipe and then through the four-way reversing valve to release heat and condense. The high-pressure liquid refrigerant after condensing and releasing heat flows through the throttling electronic expansion valve to throttle and reduce the pressure to a low-temperature and low-pressure refrigerant liquid. The throttled low-temperature and low-pressure refrigerant liquid evaporates and absorbs heat in the fin heat exchanger. The low-temperature and low-pressure refrigerant liquid absorbs the heat in the ambient air and evaporates into a low-temperature and low-pressure gas refrigerant. The cooling fan convects and absorbs heat with the fin heat exchanger. The low-temperature and low-pressure gas refrigerant is sucked into the compressor by the four-way reversing valve and compressed to realize the hot water making circulation of the heat pump water heater;

[0015] Regarding the hot water circuit circulation, the hot water from the outlet of the plate heat exchanger enters the heat preservation circulating water tank through the copper pipe. The hot water supplemented by the heat preservation circulating water tank is mixed with the hot water in the heat preservation circulating water tank and then is sucked into the plate heat exchanger by the circulating water pump to exchange heat with the high-temperature and high-pressure refrigerant, thus completing the hot water making circulation;

[0016] Select the operating mode of the air source heat pump water heater as the refrigeration mode or the heating mode according to the return water temperature;

[0017] Adjust the refrigerant flow rate through the superheat control method of the electronic expansion valve and the outside temperature control method.

[0018] Preferably, it further includes a plate heat exchanger inlet temperature sensor, a plate heat exchanger outlet temperature sensor, a water outlet temperature sensor and a water return temperature sensor;

[0019] The incoming temperature sensor is installed on the water inlet pipe of the plate heat exchanger, and is used to monitor the temperature of the circulating water entering the plate heat exchanger in real time;

[0020] The outgoing temperature sensor of the plate heat exchanger is installed on the water outlet pipe of the plate heat exchanger, and is used to monitor the temperature of the circulating water flowing out after heat exchange in the plate heat exchanger in real time;

[0021] The water outlet temperature sensor is installed at the water outlet pipeline of the heat preservation circulating water tank, and is used to detect the temperature of the return water flowing out from the heat preservation circulating water tank;

[0022] The return water temperature sensor is installed on the return water pipe of the circulating water pump, and is used to measure the temperature of the return water flowing back to the heat preservation circulating water tank.

[0023] Preferably, it further includes an external coil temperature sensor and an external air temperature sensor;

[0024] The external coil temperature sensor is installed on the external coil of the finned heat exchanger, and is used to monitor the external coil temperature in real time;

[0025] The external air temperature sensor is arranged in the external environment at the finned heat exchanger, and is used to measure the external air temperature.

[0026] Preferably, the heat preservation circulating water tank is provided with an automatic exhaust valve for discharging air; a liquid level switch for monitoring the water level is arranged inside the heat preservation circulating water tank; an auxiliary electric heater for heating the water inside the tank is arranged inside the heat preservation circulating water tank; a circulating water tank temperature sensor for monitoring the water temperature is arranged inside the heat preservation circulating water tank; a water replenishing port is arranged on the heat preservation circulating water tank; a side outlet for providing hot water is arranged on the side wall of the heat preservation circulating water tank.

[0027] Preferably, the refrigerant flow rate is adjusted by the superheat control method of the electronic expansion valve, which specifically includes the following steps:

[0028] When the operating mode of the air source heat pump water heater is the heating mode and the exhaust temperature < [d2] - 20 °C, based on the first temperature difference calculated from the suction temperature and the external coil temperature, the opening degree of the electronic expansion valve is dynamically adjusted;

[0029] When the operating mode of the air source heat pump water heater is the heating mode and [d2] > the exhaust temperature > [d2] - 10 °C, based on the second temperature difference calculated from the suction temperature and the external coil temperature, the opening degree of the electronic expansion valve is dynamically adjusted.

[0030] Preferably, when the operating mode of the air source heat pump water heater is the heating mode and the exhaust temperature < [d2] - 20°C, based on the first temperature difference calculated from the suction temperature and the outer coil temperature, the opening of the electronic expansion valve is dynamically adjusted, which specifically includes the following steps:

[0031] When the first temperature difference ≤ [d5] - 10°C, adjust the opening of the electronic expansion valve to the first opening;

[0032] At When, adjust the opening of the electronic expansion valve to the second opening;

[0033] At When, adjust the opening of the electronic expansion valve to the third opening;

[0034] At When, adjust the opening of the electronic expansion valve to the fourth opening;

[0035] At When, adjust the opening of the electronic expansion valve to the fifth opening;

[0036] At When, adjust the opening of the electronic expansion valve to the sixth opening;

[0037] When the first temperature difference ≥ [d5] + 10°C, adjust the opening of the electronic expansion valve to the seventh opening.

[0038] Preferably, when the operating mode of the air source heat pump water heater is the heating mode and [d2] > exhaust temperature > [d2] - 10°C, based on the second temperature difference calculated from the suction temperature and the outer coil temperature, the opening of the electronic expansion valve is dynamically adjusted, which specifically includes the following steps:

[0039] At Adjust the opening of the electronic expansion valve to the second opening;

[0040] At When, adjust the opening of the electronic expansion valve to the third opening;

[0041] At When, adjust the opening of the electronic expansion valve to the third opening;

[0042] At When, adjust the opening of the electronic expansion valve to the fifth opening;

[0043] At When, adjust the opening of the electronic expansion valve to the sixth opening.

[0044] Preferably, the refrigerant flow rate is adjusted by the superheat control method and the outside temperature control method of the electronic expansion valve, which specifically includes the following steps:

[0045] Compare the outside air temperature with a first preset outside air temperature threshold value and a second preset outside air temperature threshold value;

[0046] If the outside air temperature is higher than the first preset outside air temperature threshold value, adjust the opening degree of the electronic expansion valve to a first heating opening degree;

[0047] If the outside air temperature is between the first preset outside air temperature threshold value and the second preset outside air temperature threshold value, adjust the opening degree of the electronic expansion valve to a second heating opening degree;

[0048] If the outside air temperature is higher than the second preset outside air temperature threshold value, adjust the opening degree of the electronic expansion valve to a third heating opening degree.

[0049] Preferably, it further includes:

[0050] Condition 1: The cumulative operation time of the compressor in the electric heating operation is greater than or equal to the defrosting time setting value [c1], or after the last defrosting ends, the cumulative operation time of the compressor restarting the heating operation is greater than or equal to the entering defrosting time setting value [c1];

[0051] Condition 2: The continuous operation time of the compressor reaches a preset time threshold value;

[0052] Condition 3: The outside air temperature - the outside coil temperature ≥ [c3] within a continuous time;

[0053] Condition 4: The outside coil temperature ≤ [c5];

[0054] Condition 5: The outside air temperature - the suction temperature > [c6];

[0055] Condition 6: The outside air temperature < [c8];

[0056] If one of the two compressor systems simultaneously meets the above Condition 1, Condition 2, Condition 3, Condition 4 and Condition 6 or directly meets Condition 1, Condition 2, Condition 5 and Condition 6 and then enters defrosting, then the other compressor system also enters defrosting simultaneously.

[0057] Preferably, it further includes:

[0058] When the air source heat pump water heater meets the following conditions, it automatically enters the antifreeze work;

[0059] The outside air temperature is lower than ℃;

[0060] When the return water temperature or the outlet water temperature ≤ [b6], start the circulating water pump, and when the return water temperature, the outlet water temperature and the temperature of the heat preservation circulating water tank are all greater than or equal to ℃, turn off the circulating water pump.

[0061] When the temperature of the heat preservation circulating water tank ≤ [b6], start the auxiliary electric heating inside the heat preservation circulating water tank; when the temperature of the heat preservation circulating water tank is greater than or equal to [b6] °C, turn off the auxiliary electric heating inside the heat preservation circulating water tank.

[0062] When the return water temperature or the outlet water temperature or the temperature of the heat preservation circulating water tank ≤ [b7], start the circulation water pump; when the return water temperature and the temperature of the heat preservation circulating water tank are both greater than or equal to [b7] °C, turn off all equipment and enter the standby state.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] The plate heat exchanger in the present invention realizes the efficient heat exchange between the refrigerant and the circulating water. The basis is that the high-temperature and high-pressure gas-liquid mixed refrigerant condenses in the plate heat exchanger and releases heat to the circulating water, ensuring the production efficiency of hot water; the finned heat exchanger absorbs heat by convection with the outside through the heat dissipation fan, and is equipped with deicing electric heating to prevent frosting of the fins, ensuring the efficient progress of the refrigerant evaporation heat absorption process, and further ensuring the high efficiency of the entire hot water production cycle. It can select the refrigeration or heating mode according to the return water temperature, and the system can flexibly adjust the operation mode according to the actual working conditions, meet the requirements for hot water or refrigeration under different ambient temperatures, and improve the applicability of the equipment. The refrigerant flow is regulated by the superheat control method of the electronic expansion valve and the external temperature control method. This regulation method can accurately match the refrigerant flow according to factors such as the system operation state and the external ambient temperature, improve the heating or refrigeration performance of the system, and reduce energy waste at the same time. Brief Description of the Drawings

[0065] Figure 1 It is a schematic structural diagram of the control method of the air source heat pump water heater proposed by the present invention;

[0066] Figure 2 It is a schematic diagram of the relationship between the ambient temperature and the heating opening degree in the heating mode of the control method of the air source heat pump water heater proposed by the present invention.

[0067] 1. Compressor; 101. Suction temperature sensor; 102. Discharge temperature sensor; 2. Copper pipe; 3. Four-way reversing valve; 4. Plate heat exchanger; 401. Plate heat exchanger inlet temperature sensor; 402. Plate heat exchanger outlet temperature sensor; 403. Outlet water temperature sensor; 404. Return water temperature sensor; 5. Throttle electronic expansion valve; 6. Finned heat exchanger; 601. Deicing electric heating; 602. Outer coil temperature sensor; 603. Outer air temperature sensor; 7. Heat dissipation fan; 8. Circulation water pump; 9. Heat preservation circulating water tank; 901. Auxiliary electric heating; 902. Circulating water tank temperature sensor; 903. Liquid level switch; 904. Water replenishing port; 905. Side outlet; 906. Automatic exhaust valve. Detailed Embodiments

[0068] Refer toFigures 1 to 2 as shown

[0069] Embodiment 1 further illustrates the air source heat pump water heater control method proposed by the present invention.

[0070] The air source heat pump water heater control method includes a compressor 1, a copper pipe 2, a four-way reversing valve 3, a plate heat exchanger 4, a throttling electronic expansion valve 5, a finned heat exchanger 6, a cooling fan 7, a circulating water pump 8, and a heat preservation circulating water tank 9:

[0071] The compressor 1 is provided with a suction temperature sensor 101 and a discharge temperature sensor 102. The suction temperature sensor 101 is used to monitor the suction temperature of the low-temperature and low-pressure refrigerant entering the compressor 1, and the discharge temperature sensor 102 is used to monitor the discharge temperature of the high-temperature and high-pressure refrigerant gas discharged after being compressed by the compressor 1;

[0072] The plate heat exchanger 4 is connected to the compressor 1 through the copper pipe 2. The high-temperature and high-pressure refrigerant gas generated by the compressor 1 releases heat to the circulating water through the plate heat exchanger 4 to realize the heat exchange between the refrigerant and the circulating water;

[0073] The throttling electronic expansion valve 5 is connected to the finned heat exchanger 6 through the copper pipe 2. The throttling electronic expansion valve 5 throttles and reduces the pressure of the high-temperature and high-pressure refrigerant liquid to make it become a low-temperature and low-pressure gas-liquid mixture. The other end of the throttling electronic expansion valve 5 is connected to the plate heat exchanger 4;

[0074] The interfaces of the four-way reversing valve 3 are respectively connected to the throttling electronic expansion valve 5, the finned heat exchanger 6, the plate heat exchanger 4, and the compressor 1. The four-way reversing valve 3 switches the refrigerant flow direction in the refrigeration and heating cycles by changing the position of the internal spool;

[0075] The finned heat exchanger 6 is connected to the interface of the four-way reversing valve 3. The low-temperature and low-pressure gas-liquid mixed refrigerant absorbs heat from the outside air in the finned heat exchanger 6 and transfers it to the circulating water together with the heat generated by the work of the compressor 1. The finned heat exchanger 6 is provided with an anti-icing electric heater 601, and the finned heat exchanger 6 is used to prevent frosting on the fin surface; the cooling fan 7 is arranged near the finned heat exchanger 6;

[0076] The water inlet of the circulating water pump 9 is connected to the circulating water outlet of the plate heat exchanger 4. The circulating water pump 9 transports the cooled circulating water to the water return port of the heat preservation circulating water tank 9 to provide power for the flow of the circulating water;

[0077] Regarding the refrigerant circuit cycle, when making hot water, in the outdoor heating working environment temperature of the air source heat pump water heater, the low-temperature and low-pressure gaseous refrigerant is compressed by the compressor 1 into a high-temperature and high-pressure refrigerant gas. The high-temperature and high-pressure refrigerant gas passes through the copper pipe 2 and then enters the plate heat exchanger 4 through the four-way reversing valve 3 to release heat and condense. The high-pressure liquid refrigerant after condensing and releasing heat flows through the throttling electronic expansion valve 5 to throttle and depressurize into a low-temperature and low-pressure refrigerant. The throttled low-temperature and low-pressure refrigerant evaporates and absorbs heat in the fin heat exchanger 6. The low-temperature and low-pressure refrigerant absorbs the heat in the ambient air and evaporates into a low-temperature and low-pressure gaseous refrigerant. The heat dissipation fan 7 convects and absorbs heat with the fin heat exchanger 6. The low-temperature and low-pressure gaseous refrigerant is sucked into the compressor 1 through the four-way reversing valve 3 for compression to realize the hot water making cycle of the heat pump water heater;

[0078] Regarding the hot water circuit cycle, the hot water from the outlet of the plate heat exchanger 4 enters the heat preservation circulation water tank 9 through the copper pipe 2. The hot water supplemented by the heat preservation circulation water tank 9 is mixed with the hot water in the heat preservation circulation water tank 9 and then is sucked into the plate heat exchanger 4 by the circulation water pump 8 to exchange heat with the high-temperature and high-pressure refrigerant, thus completing the hot water making cycle;

[0079] Select the operating mode of the air source heat pump water heater as the refrigeration mode or the heating mode according to the return water temperature;

[0080] Adjust the refrigerant flow rate through the superheat control method of the electronic expansion valve and the external temperature control method.

[0081] The present invention can perform efficient heating and refrigeration switching, can intelligently select the refrigeration or heating mode according to the return water temperature, realize flexible switching, meet the requirements under different environmental temperatures, and improve the applicability and energy utilization efficiency of the equipment. By adjusting the refrigerant flow rate through the superheat control method of the electronic expansion valve and the external temperature control method, the system load can be accurately matched, the heating and refrigeration performance can be improved, and the energy consumption can be reduced. The fin heat exchanger is provided with an anti-icing electric heating device, which effectively prevents frosting on the fin surface, ensures the stable operation of the equipment in a low-temperature environment, and prolongs the service life of the equipment. The setting of the plate heat exchanger and the fin heat exchanger realizes sufficient heat exchange between the refrigerant and the circulating water and the ambient air, and improves the heating and refrigeration effects of the system. The circulation water pump provides power for the flow of the circulating water, ensures the stability of the hot water circuit and the refrigerant circuit cycle, and enables the system to operate continuously and reliably.

[0082] Embodiment 2 adds the following technical features on the basis of Embodiment 1:

[0083] The control method of the air source heat pump water heater further includes a plate heat exchanger inlet temperature sensor 401, a plate heat exchanger outlet temperature sensor 402, a water outlet temperature sensor 403, and a return water temperature sensor 404;

[0084] The incoming temperature sensor 401 is installed on the water inlet pipe of the plate heat exchanger 4. The incoming temperature sensor 401 is used to monitor the temperature of the circulating water entering the plate heat exchanger 4 in real time;

[0085] The outgoing temperature sensor 402 of the plate heat exchanger is installed on the water outlet pipe of the plate heat exchanger 4. The outgoing temperature sensor 402 of the plate heat exchanger is used to monitor the temperature of the circulating water flowing out after heat exchange through the plate heat exchanger 4 in real time;

[0086] The outlet water temperature sensor 403 is installed at the outlet pipe of the heat preservation circulating water tank 9. The outlet water temperature sensor 403 is used to detect the temperature of the return water flowing out of the heat preservation circulating water tank 9;

[0087] The return water temperature sensor 404 is installed on the return water pipe of the circulating water pump 8. The return water temperature sensor 404 is used to measure the temperature of the return water flowing back into the heat preservation circulating water tank 9.

[0088] The incoming temperature sensor 401 is used to monitor the temperature of the fluid entering the plate heat exchanger, providing temperature data at this key position for the system. So that the system can adjust operation parameters such as refrigerant flow according to this temperature information, ensure that the heat exchange efficiency of the plate heat exchanger is in an ideal state, and make the entire heat pump water heater system operate stably and efficiently.

[0089] The outgoing temperature sensor 402 of the plate heat exchanger can detect the temperature of the fluid after heat exchange through the plate heat exchanger. By comparing with the data of the incoming temperature sensor 401, it can intuitively reflect the heat exchange effect of the plate heat exchanger. The system can adjust the operation strategy according to this temperature data to ensure that the output hot water temperature meets the set requirements.

[0090] The main function of the outlet water temperature sensor 403 is to monitor the temperature of the hot water output by the heat pump water heater in real time, which is a key parameter to measure whether the hot water supply meets the user's needs. The system can accurately control the heating process according to this temperature feedback to ensure that the outlet water temperature is stable within the set range and provide hot water at a suitable temperature for users.

[0091] The return water temperature sensor 404 is used to measure the temperature of the circulating water returning from the user end to the heat pump water heater. This temperature data is crucial for the system to judge the current heat load situation. The system can select the operation mode (refrigeration or heating) according to the return water temperature and adjust relevant operation parameters to achieve efficient heat recovery and utilization and improve energy utilization efficiency.

[0092] Embodiment 3 adds the following technical features on the basis of Embodiment 2:

[0093] The control method of the air source heat pump water heater further includes an external coil temperature sensor 602 and an external air temperature sensor 603;

[0094] The external coil temperature sensor 602 is installed on the external coil of the finned heat exchanger 6 and is used to monitor the external coil temperature in real time;

[0095] The external air temperature sensor 603 is set in the external environment at the location of the finned heat exchanger 6 and is used to measure the external air temperature.

[0096] The heat preservation circulating water tank 9 is provided with an automatic exhaust valve 906 for exhausting air; a liquid level switch 903 for monitoring the water level is arranged inside the heat preservation circulating water tank 9; an auxiliary electric heater 901 for heating the water inside the tank is arranged inside the heat preservation circulating water tank 9; a circulating water tank temperature sensor 902 for monitoring the water temperature is arranged inside the heat preservation circulating water tank 9; a water replenishing port 904 is arranged on the heat preservation circulating water tank 9; a side outlet 905 for providing hot water is arranged on the side wall of the heat preservation circulating water tank 9.

[0097] The external coil temperature sensor 602 and the external air temperature sensor 603 monitor the external coil and external air temperatures in real time, providing an accurate basis for adjusting the operation modes such as defrosting and heating of the system, improving the control accuracy and heating effect. The circulating water tank temperature sensor 902 accurately monitors the water temperature, and the auxiliary electric heater works as required to ensure the water temperature stability and meet the hot water demand of users.

[0098] The automatic exhaust valve 906 of the heat preservation circulating water tank 9 discharges air in time, avoiding air resistance from affecting the water circulation and ensuring the stable operation of the system; the liquid level switch 903 monitors the water level in real time to prevent the heat preservation circulating water tank 9 from lacking water or abnormal water level from affecting the normal operation of the system.

[0099] The heat preservation circulating water tank 9 is provided with a water replenishing port 904 and a side outlet 905, facilitating the water replenishing operation, being able to stably provide hot water, meeting the hot water usage demands in different scenarios. The auxiliary electric heater 901 is put into operation at low temperatures or during peak hot water demands to supplement heat, ensuring the reliability and stability of the hot water supply.

[0100] The external coil temperature sensor 602 is installed on the external coil of the finned heat exchanger 6 to monitor the external coil temperature in real time; the external air temperature sensor 603 is set in the external environment of the finned heat exchanger 6 to measure the external air temperature. The system judges whether the defrosting conditions are met according to parameters such as the temperature difference between the two (such as the defrosting condition judgment logic mentioned before), controls the defrosting operation, and ensures the efficient heat exchange of the finned heat exchanger 6. The circulating water tank temperature sensor 902 monitors the water temperature in the heat preservation circulating water tank 9. When the water temperature is lower than the set value and auxiliary heating is required, the auxiliary electric heater 901 starts to heat the water in the heat preservation circulating water tank 9 and stops when the set temperature is reached, maintaining the water temperature stability.

[0101] The circulating water pump 8 drives the circulating water to flow in the system. The hot water enters the heat preservation circulating water tank 9 from the plate heat exchanger 402. After the water in the heat preservation circulating water tank 9 is mixed with the makeup water, it is sent into the plate heat exchanger 4 by the circulating water pump again to exchange heat with the refrigerant. The automatic exhaust 906 discharges the air in the heat preservation circulating water tank 9 to prevent air resistance from affecting the water circulation. The liquid level switch 903 monitors the water level in the heat preservation circulating water tank 9 in real time. When the water level is too low, makeup water operation is carried out through the makeup water port 904 to ensure that there is enough water in the tank to supply hot water. The hot water flows out from the side outlet 905 of the heat preservation circulating water tank 9 for users to use.

[0102] Under normal heating conditions, the refrigerant realizes the heating cycle through the compressor 1, the plate heat exchanger 4, the throttling electronic expansion valve 5, the finned heat exchanger 6, etc., to provide heat for the circulating water. When the ambient temperature is relatively low or the hot water demand is large, the auxiliary electric heater 901 is started to supplement additional heat to ensure stable hot water supply.

[0103] The refrigerant flow rate is adjusted by the superheat control method of the electronic expansion valve, which specifically includes the following steps:

[0104] When the operating mode of the air source heat pump water heater is the heating mode and the exhaust temperature < [d2] - 20°C, based on the first temperature difference calculated from the suction temperature and the outer coil temperature, the opening of the electronic expansion valve is dynamically adjusted;

[0105] When the operating mode of the air source heat pump water heater is the heating mode and [d2] > exhaust temperature > [d2] - 10°C, based on the second temperature difference calculated from the suction temperature and the outer coil temperature, the opening of the electronic expansion valve is dynamically adjusted.

[0106] Precisely adjusting the refrigerant flow rate, dynamically adjusting the opening of the electronic expansion valve according to different exhaust temperature ranges and the temperature difference calculated from the suction temperature and the outer coil temperature, can precisely adjust the refrigerant flow rate, enabling the system to always maintain a high-efficiency operating state in the heating mode. Through the above precise adjustment, problems such as unstable system operation caused by too large or too small refrigerant flow rate, such as compressor liquid slugging and insufficient heat exchange in the evaporator, are avoided, improving the stability and reliability of the operation of the air source heat pump water heater. Reasonable refrigerant flow rate adjustment helps to improve the heat exchange efficiency of the evaporator, thereby enhancing the heating capacity of the entire system, ensuring stable hot water supply for users under different working conditions. Precise refrigerant flow rate control enables the system to meet the heating demand while reducing unnecessary energy consumption, improving energy utilization efficiency, and achieving the effect of energy conservation and consumption reduction.

[0107] When the air source heat pump water heater operates in the heating mode and the exhaust temperature < [d2] - 20°C, the system calculates the first temperature difference based on the suction temperature and the external coil temperature. The suction temperature sensor monitors the suction temperature of the low-temperature and low-pressure refrigerant entering the compressor, and the external coil temperature sensor monitors the temperature of the external coil of the finned heat exchanger. These two temperature data are transmitted to the control system, and the difference between them, that is, the first temperature difference, is calculated. The control system dynamically adjusts the opening degree of the electronic expansion valve according to the magnitude of this first temperature difference. If the first temperature difference is large, it indicates that the refrigerant in the evaporator evaporates relatively fully, and it may be necessary to appropriately increase the opening degree of the electronic expansion valve to increase the refrigerant flow rate; conversely, if the first temperature difference is small, then appropriately reduce the opening degree of the electronic expansion valve to reduce the refrigerant flow rate to ensure that the heat exchange efficiency of the evaporator is in the best state.

[0108] When the air source heat pump water heater is in the heating mode and [d2] > exhaust temperature > [d2] - 10°C, the system calculates the second temperature difference based on the suction temperature and the external coil temperature. Similarly, the suction temperature sensor and the external coil temperature sensor respectively obtain the corresponding temperature data, and the control system calculates the second temperature difference. Then, based on this second temperature difference, the opening degree of the electronic expansion valve is dynamically adjusted according to specific control rules. In this exhaust temperature range, through the analysis and processing of the second temperature difference, the electronic expansion valve can accurately control the refrigerant flow rate according to the actual working conditions, ensuring the stable and efficient operation of the system under this working condition, meeting the heating requirements and achieving energy-saving effects.

[0109] System Function Setting Table

[0110]

[0111] Protection Parameter Table

[0112]

[0113]

[0114] Defrosting Parameter Table

[0115]

[0116] Electronic Expansion Valve Parameter Table (When selecting a 480-step valve, the maximum opening degree is 60°)

[0117]

[0118]

[0119] Electronic Expansion Valve Parameter Table (When selecting a 480-step valve, the maximum opening degree is 60°)

[0120]

[0121]

[0122] Example 4 adds the following technical features on the basis of Example 3:

[0123] For the air source heat pump water heater control method, when the operation mode of the air source heat pump water heater is the heating mode and the exhaust gas temperature < [d2] - 20 °C, based on the first temperature difference calculated from the suction temperature and the external coil temperature, the opening degree of the electronic expansion valve is dynamically adjusted. Specifically, it includes the following steps:

[0124] When the first temperature difference ≤ [d5] - 10 °C, adjust the opening degree of the electronic expansion valve to the first opening degree;

[0125] At Adjust the opening degree of the electronic expansion valve to the second opening degree;

[0126] At Adjust the opening degree of the electronic expansion valve to the third opening degree;

[0127] At Adjust the opening degree of the electronic expansion valve to the fourth opening degree;

[0128] At Adjust the opening degree of the electronic expansion valve to the fifth opening degree;

[0129] At Adjust the opening degree of the electronic expansion valve to the sixth opening degree;

[0130] When the first temperature difference ≥ [d5] + 10 °C, adjust the opening degree of the electronic expansion valve to the seventh opening degree.

[0131] By dividing multiple precise intervals according to the first temperature difference calculated from the suction temperature and the external coil temperature to adjust the opening degree of the electronic expansion valve, the refined adjustment of the refrigerant flow rate is achieved, which can more accurately match the heating demand of the system. The refined adjustment enables the evaporator to maintain good heat exchange efficiency under different working conditions, improves the heating performance of the air source heat pump water heater, and ensures stable and efficient hot water supply. Setting different opening degrees for different first temperature difference intervals enhances the adaptability of the system to different working conditions such as ambient temperature and load, and reduces the performance fluctuations caused by changes in working conditions. Precise control of the refrigerant flow rate avoids energy waste caused by unreasonable flow rate, reduces energy consumption while ensuring the heating effect, and improves the energy utilization efficiency.

[0132]

[0133] Example 5 adds the following technical features on the basis of Example 4:

[0134] Air source heat pump water heater control method. When the operating mode of the air source heat pump water heater is the heating mode and [d2] > exhaust gas temperature > [d2] - 10°C, based on the second temperature difference calculated from the suction temperature and the external coil temperature, the opening degree of the electronic expansion valve is dynamically adjusted. Specifically, it includes the following steps:

[0135] At Adjust the opening degree of the electronic expansion valve to the second opening degree;

[0136] At Adjust the opening degree of the electronic expansion valve to the third opening degree;

[0137] At Adjust the opening degree of the electronic expansion valve to the third opening degree;

[0138] At Adjust the opening degree of the electronic expansion valve to the fifth opening degree;

[0139] At Adjust the opening degree of the electronic expansion valve to the sixth opening degree.

[0140] Precisely adjust the opening degree of the electronic expansion valve according to different second temperature difference ranges to achieve precise control of the refrigerant flow rate, ensure the stable operation of the system under specific heating conditions. Precise control of the refrigerant flow rate can enable the evaporator and condenser to function better, improve the heating efficiency of the system, reduce energy waste, and enhance energy utilization efficiency. Set different opening degrees for different second temperature differences, enabling the system to better adapt to different ambient temperatures and operating conditions, and ensuring a stable heating effect under various conditions. Reasonable adjustment of the opening degree of the electronic expansion valve helps reduce the load fluctuation of the compressor, extend the service life of the equipment, and simultaneously improve the performance and reliability of the entire air source heat pump water heater system.

[0141]

[0142] When the exhaust gas temperature ≥ [d2], adjust to open two degrees more every cycle.

[0143] After the compressor 1 is turned off, adjust the opening degree of the electronic expansion valve 5 according to the ambient temperature every 2 minutes.

[0144] 300 seconds after shutdown, open the valve with the maximum number of pulses, and then adjust the initial opening degree according to the ambient temperature. The opening degree in the shutdown state remains unchanged.

[0145] Embodiment six adds the following technical features on the basis of Embodiment five:

[0146] Air source heat pump water heater control method. Adjust the refrigerant flow rate through the superheat control method and the external temperature control method of the electronic expansion valve. Specifically, it includes the following steps:

[0147] Compare the outside air temperature with a first preset outside air temperature threshold and a second preset outside air temperature threshold;

[0148] If the outside air temperature is higher than the first preset outside air temperature threshold, adjust the opening degree of the electronic expansion valve to the first heating opening degree;

[0149] If the outside air temperature is between the first preset outside air temperature threshold and the second preset outside air temperature threshold, adjust the opening degree of the electronic expansion valve to the second heating opening degree;

[0150] If the outside air temperature is higher than the second preset outside air temperature threshold, adjust the opening degree of the electronic expansion valve to the third heating opening degree.

[0151] The default value of the first heating opening degree is 31°, the default value of the second heating opening degree is 19°, and the third heating opening degree is 3.

[0152] Adjusting the opening degree of the electronic expansion valve according to the comparison between the outside air temperature and the preset threshold can enable the system to better adapt to different external environmental temperatures, ensuring stable operation under various climate conditions. By reasonably adjusting the opening degree of the electronic expansion valve, the optimized control of the refrigerant flow rate is achieved, improving the working efficiency of the evaporator and condenser, and thus enhancing the heating performance of the air source heat pump water heater. Precise control of the refrigerant flow rate avoids energy waste, reduces energy consumption while meeting the heating demand, improves energy utilization efficiency, and helps reduce operating costs. An appropriate refrigerant flow rate ensures the stable operation of each component of the system, reduces system failures caused by improper refrigerant flow rate, extends the service life of the equipment, and enhances the reliability of the system.

[0153] When the ambient temperature < 0°C and the compressor is off, the oil temperature electric heater is on;

[0154] When the ambient temperature ≥ 5°C or when the corresponding compressor starts, the oil temperature electric heater is off;

[0155] When the measured temperature T < the set temperature - the compressor return difference temperature [a10], the compressor loads, and the different compressor loading intervals are 30 seconds. It loads until the measured temperature T ≥ the set temperature, then the compressor unloads, and the different compressor unloading intervals are 5 seconds.

[0156] It is prohibited to operate when the outdoor temperature > the auxiliary electric heating ambient temperature [c9].

[0157] 5°C ≤ T set - T water tank, turn on the electric heater;

[0158] 5°C > T set - T water tank > 2°C, maintain;

[0159] T set - T water tank ≤ 2°C, turn off the electric heater.

[0160] Note: When disinfecting with high temperature, the electric heating of the hot water tank is forced to turn on.

[0161] When the outdoor temperature is relatively low, to prevent the bottom of the outdoor finned heat exchanger from freezing, when the following conditions are met, the defrosting electric heating of the finned heat exchanger operates for heating:

[0162] When starting the machine in the heating (hot water) mode, it turns on when the compressor turns on;

[0163] It is always on during defrosting;

[0164] It turns off when any of the following conditions is met:

[0165] Non-heating (hot water) mode;

[0166] When the ambient temperature ≥ 20°C, it turns off;

[0167] When 18 ≤ ambient temperature < 20°C, it remains on.

[0168] When [a1] = 1 and in the liquid level mode, use the high liquid level switch.

[0169] When the exhaust temperature is lower than [b15] - [b16], the fan is allowed to operate;

[0170] When [b15] - [b16] ≤ exhaust temperature ≤ [b15], it remains on;

[0171] When the exhaust temperature is higher than [b15], stop the fan.

[0172] Embodiment Seven adds the following technical features on the basis of Embodiment Six:

[0173] The control method of the air source heat pump water heater further includes:

[0174] Condition One: The cumulative operation time of the electric heating operation of Compressor 1 is greater than or equal to the defrosting time set value [c1], or after the last defrosting ends, the cumulative operation time of Compressor 1 restarting the heating operation is greater than or equal to the defrosting entry time set value [c1];

[0175] Condition Two: The continuous operation time of the compressor reaches the preset time threshold;

[0176] Condition Three: The external air temperature - the external coil temperature ≥ [c3] for a continuous period;

[0177] Condition Four: The external coil temperature ≤ [c5];

[0178] Condition Five: The external air temperature - the suction temperature > [c6];

[0179] Condition Six: The external air temperature < [c8];

[0180] If one of the two compressor systems meets the above Conditions 1, 2, 3, 4, and 6 simultaneously or directly meets Conditions 1, 2, 5, and 6, defrosting is initiated, and the other compressor system also enters defrosting simultaneously.

[0181] By setting multiple conditions to comprehensively judge whether to enter defrosting, the frosting condition of the external coil of the finned heat exchanger can be accurately identified, unnecessary defrosting operations can be avoided, and heating interruption and energy waste caused by frequent defrosting can be reduced. Timely and accurate defrosting can prevent excessive frosting of the external coil from affecting the heat exchange efficiency, ensuring that the air source heat pump water heater always maintains a high heating efficiency during the heating process and stably provides hot water. The coordinated defrosting of the two compressor systems ensures the consistency and stability of the system operation, avoiding system imbalance problems that may occur when one compressor system defrosts while the other continues to operate for heating, and extending the service life of the equipment. The judgment method with a combination of multiple conditions enables the system to adapt to different working conditions such as ambient temperature and humidity, and can reliably control defrosting under complex and changeable external conditions.

[0182] Embodiment 8 adds the following technical features on the basis of Embodiment 7:

[0183] The air source heat pump water heater control method further includes:

[0184] The air source heat pump water heater automatically enters the anti-freezing operation when the following conditions are met;

[0185] The external air temperature is lower than 10°C;

[0186] When the return water temperature or the outlet water temperature ≤ [b6], the circulating water pump 8 is started, and when the return water temperature, the outlet water temperature, and the temperature of the heat preservation circulating water tank are all greater than or equal to 10°C, the circulating water pump 8 is closed.

[0187] When the temperature of the heat preservation circulating water tank 9 ≤ [b6], the auxiliary electric heating inside the heat preservation circulating water tank 9 is started, and when the temperature of the heat preservation circulating water tank is greater than or equal to 10°C, the auxiliary electric heating inside the heat preservation circulating water tank 9 is closed.

[0188] When the return water temperature or the outlet water temperature or the temperature of the heat preservation circulating water tank ≤ [b7], the circulating water pump 8 is started, and when the return water temperature and the temperature of the heat preservation circulating water tank 9 are both greater than or equal to 10°C, all equipment is closed and the standby state is entered.

[0189] By setting conditions such as the outside air temperature, the air source heat pump water heater can actively enter the anti-freezing operation in a low-temperature environment, effectively prevent the equipment from being damaged by low-temperature freezing, and extend the service life of the equipment. According to parameters such as the return water temperature, the outlet water temperature, and the temperature of the heat preservation circulating water tank, the start and stop of the circulating water pump and the auxiliary electric heating are accurately controlled to ensure the temperature stability of the system during the anti-freezing process and avoid energy waste. The entire anti-freezing operation process does not require manual intervention. The system automatically monitors the temperature and performs corresponding operations, improving the operation convenience and reliability and reducing the manual maintenance cost. It effectively prevents problems such as pipeline rupture and equipment failure caused by the freezing of the water system, ensures the stable operation of the air source heat pump water heater system, reduces the downtime, and improves the continuity of hot water supply.

[0190] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling an air source heat pump water heater, characterized in that: It includes a compressor (1), a copper tube (2), a four-way reversing valve (3), a plate heat exchanger (4), a throttling electronic expansion valve (5), a finned heat exchanger (6), a cooling fan (7), a circulating water pump (8), and a heat-insulating circulating water tank (9): The compressor (1) is provided with an intake temperature sensor (101) and an exhaust temperature sensor (102), wherein the intake temperature sensor (101) is used to monitor the intake temperature of low-temperature and low-pressure refrigerant entering the compressor (1), and the exhaust temperature sensor (102) is used to monitor the exhaust temperature of high-temperature and high-pressure refrigerant gas discharged after being compressed by the compressor (1); The plate heat exchanger (4) is connected to the compressor (1) via a copper tube (2), and the high-temperature and high-pressure refrigerant gas generated by the compressor (1) releases heat to the circulating water through the plate heat exchanger (4), thereby achieving heat exchange between the refrigerant and the circulating water; The throttling electronic expansion valve (5) is connected to the finned heat exchanger (6) via a copper tube (2); the throttling electronic expansion valve (5) throttles and reduces the pressure of the high-temperature and high-pressure refrigerant liquid to convert it into a low-temperature and low-pressure gas-liquid mixture; the other end of the throttling electronic expansion valve (5) is connected to the plate heat exchanger (4); The interfaces of the four-way reversing valve (3) are respectively connected to the throttling electronic expansion valve (5), the finned heat exchanger (6), the plate heat exchanger (4) and the compressor (1), and the four-way reversing valve (3) switches the flow direction of the refrigerant in the cooling and heating cycles by changing the position of the internal valve core; The finned heat exchanger (6) is connected to the interface of the four-way reversing valve (3); the low-temperature and low-pressure gas-liquid mixed refrigerant absorbs heat from the outside air in the finned heat exchanger (6) and transfers it to the circulating water together with the heat generated by the work of the compressor (1); the finned heat exchanger (6) is provided with an electric deicing heater (601); the finned heat exchanger (6) is used to prevent frost on the fin surface; the heat dissipation fan (7) is arranged near the finned heat exchanger (6); The water inlet of the circulating water pump (9) is connected to the circulating water outlet of the plate heat exchanger (4), and the circulating water pump (9) transports the cooled circulating water to the return water outlet of the heat-insulating circulating water tank (9), thereby providing power for the circulation of the circulating water; Regarding the refrigerant loop circulation, during the hot water circulation, the air source heat pump water heater is at the outdoor heating working environment temperature, and the low-temperature and low-pressure gas refrigerant is compressed into a high-temperature and high-pressure refrigerant gas by the compressor (1). The high-temperature and high-pressure refrigerant gas passes through the copper tube (2) and then passes through the four-way reversing valve (3) and then enters the plate heat exchanger (4) to release heat and condense. The high-pressure liquid refrigerant after condensation and heat release flows through the throttling electronic expansion valve (5) to throttle and reduce the pressure to become a low-temperature and low-pressure liquid refrigerant. The throttled low-temperature and low-pressure liquid refrigerant evaporates and absorbs heat in the fin heat exchanger (6). The low-temperature and low-pressure liquid refrigerant absorbs heat in the ambient air and evaporates into a low-temperature and low-pressure gas refrigerant. The heat dissipation fan (7) and the fin heat exchanger (6) absorb heat by convection. The low-temperature and low-pressure gas refrigerant passes through the four-way reversing valve (3) and is sucked into the compressor (1) for compression to realize the hot water circulation of the heat pump water heater. Regarding the hot water loop circulation, the hot water from the outlet of the plate heat exchanger (4) enters the heat preservation circulation water tank (9) through the copper pipe (2), and the hot water added to the heat preservation circulation water tank (9) is mixed with the hot water in the heat preservation circulation water tank (9) and then sucked into the plate heat exchanger (4) by the circulating water pump (8) to exchange heat with the high-temperature and high-pressure refrigerant, thus completing the hot water production cycle; Select the operation mode of the air source heat pump water heater as cooling mode or heating mode according to the return water temperature; The refrigerant flow rate is adjusted by the superheat control method of the electronic expansion valve and the external temperature control method.

2. The air source heat pump water heater control method according to claim 1, characterized in that: It also includes a plate-in temperature sensor (401), a plate-out temperature sensor (402), a water outlet temperature sensor (403) and a water return temperature sensor (404); The inlet temperature sensor (401) is installed on the water inlet pipe of the plate heat exchanger (4), and the inlet temperature sensor (401) is used to monitor the temperature of the circulating water entering the plate heat exchanger (4) in real time; The plate outlet temperature sensor (402) is installed on the water outlet pipe of the plate heat exchanger (4), and the plate outlet temperature sensor (402) is used to monitor in real time the temperature of the circulating water flowing out after heat exchange through the plate heat exchanger (4); The outlet water temperature sensor (403) is installed at the outlet water pipeline of the thermal insulation circulating water tank (9), and the outlet water temperature sensor (403) is used to detect the return water temperature flowing out of the thermal insulation circulating water tank (9); The return water temperature sensor (404) is installed on the return water pipeline of the circulating water pump (8), and the return water temperature sensor (404) is used to measure the return water temperature returning to the thermal insulation circulating water tank (9).

3. The air source heat pump water heater control method according to claim 2, characterized in that: Also includes an external coil temperature sensor (602) and an external air temperature sensor (603); The outer coil temperature sensor (602) is installed on the outer coil of the finned heat exchanger (6), and the outer coil temperature sensor (602) is used to monitor the outer coil temperature in real time; The external air temperature sensor (603) is arranged in the external environment of the fin heat exchanger (6), and the external air temperature sensor (603) is used to measure the external air temperature.

4. The air source heat pump water heater control method according to claim 3, characterized in that: The thermal insulation circulating water tank (9) is provided with an automatic exhaust valve (906) for exhausting air; a liquid level switch (903) for monitoring the water level is arranged inside the thermal insulation circulating water tank (9); an auxiliary electric heater (901) for heating the water inside the water tank is arranged inside the thermal insulation circulating water tank (9); a circulating water tank temperature sensor (902) for monitoring the water temperature is arranged inside the thermal insulation circulating water tank (9); a water replenishment port (904) is arranged on the thermal insulation circulating water tank (9); and a side outlet (905) for providing hot water is arranged on the side wall of the thermal insulation circulating water tank (9).

5. The air source heat pump water heater control method according to claim 4, characterized in that: The refrigerant flow is adjusted by superheat control of the electronic expansion valve, which specifically includes the following steps: When the operation mode of the air source heat pump water heater is the heating mode and the exhaust temperature is less than [d2]-20°C, the opening of the electronic expansion valve is dynamically adjusted based on the first temperature difference calculated based on the suction temperature and the external coil temperature; When the operation mode of the air source heat pump water heater is the heating mode and [d2]>exhaust temperature>[d2]-10℃, the opening of the electronic expansion valve is dynamically adjusted based on the second temperature difference calculated based on the suction temperature and the external coil temperature.

6. The air source heat pump water heater control method according to claim 5, characterized in that: When the operation mode of the air source heat pump water heater is the heating mode and the exhaust temperature is less than [d2]-20°C, based on the first temperature difference calculated by the suction temperature and the external coil temperature, the opening of the electronic expansion valve is dynamically adjusted based on the first temperature difference, specifically including the following steps: When the first temperature difference is ≤[d5]-10°C, the opening of the electronic expansion valve is adjusted to the first opening; exist When the electronic expansion valve opening is adjusted to the second opening; exist When the electronic expansion valve opening is adjusted to the third opening; exist When the electronic expansion valve opening is adjusted to the fourth opening; exist When the electronic expansion valve is opened, adjust the opening degree of the electronic expansion valve to the fifth opening degree; exist When the electronic expansion valve opening is adjusted to the sixth opening; When the first temperature difference is ≥[d5]+10°C, the opening of the electronic expansion valve is adjusted to the seventh opening.

7. The air source heat pump water heater control method according to claim 6, characterized in that: When the operation mode of the air source heat pump water heater is the heating mode and [d2]> exhaust temperature> [d2]-10°C, based on the second temperature difference calculated by the suction temperature and the external coil temperature, the opening of the electronic expansion valve is dynamically adjusted based on the second temperature difference, specifically including the following steps: exist Adjust the opening of the electronic expansion valve to the second opening; exist When the electronic expansion valve opening is adjusted to the third opening; exist When the electronic expansion valve opening is adjusted to the third opening; exist When the electronic expansion valve is opened, adjust the opening degree of the electronic expansion valve to the fifth opening degree; exist When the electronic expansion valve opening is adjusted to the sixth opening.

8. The air source heat pump water heater control method according to claim 1, characterized in that: The refrigerant flow rate is adjusted by the superheat control method of the electronic expansion valve and the external temperature control method, which specifically includes the following steps: comparing the outside air temperature with a first preset outside air temperature threshold and a second preset outside air temperature threshold; If the outside air temperature is higher than a first preset outside air temperature threshold, the opening of the electronic expansion valve is adjusted to a first heating opening; If the outside air temperature is between the first preset outside air temperature threshold and the second preset outside air temperature threshold, the opening of the electronic expansion valve is adjusted to the second heating opening; If the outside air temperature is higher than the second preset outside air temperature threshold, the opening degree of the electronic expansion valve is adjusted to the third heating opening degree.

9. The air source heat pump water heater control method according to claim 8, characterized in that: Also includes: Condition 1: The cumulative running time of the electric heating operation of the compressor (1) is greater than or equal to the defrost time setting value [c1], or after the last defrost is completed, the cumulative running time of the heating operation of the compressor (1) is greater than or equal to the defrost time setting value [c1]; Condition 2: The continuous operation time of the compressor reaches the preset time threshold; Condition 3: Internal and external air temperature - external coil temperature ≥ [c3] during continuous time; Condition 4: External coil temperature ≤ [c5]; Condition 5: External air temperature - suction air temperature > [c6]; Condition 6: External air temperature < [c8]; If one of the two compressor systems simultaneously satisfies the above conditions 1, 2, 3, 4 and 6 or directly satisfies conditions 1, 2, 5 and 6 and enters defrosting, the other compressor system will also enter defrosting at the same time.

10. The air source heat pump water heater control method according to claim 9, characterized in that: Also includes: The air source heat pump water heater automatically enters antifreeze mode when the following conditions are met; The outside air temperature is below 10℃; When the return water temperature or the outlet water temperature is ≤[b6], the circulating water pump (8) is started; when the return water temperature, the outlet water temperature and the temperature of the heat-insulating circulating water tank are all greater than or equal to 10°C, the circulating water pump (8) is shut down. When the temperature of the thermal insulation circulating water tank (9) is ≤[b6], the auxiliary electric heating inside the thermal insulation circulating water tank (9) is started; when the temperature of the thermal insulation circulating water tank is greater than or equal to 10° C., the auxiliary electric heating inside the thermal insulation circulating water tank (9) is turned off. When the return water temperature, the outlet water temperature or the temperature of the thermal insulation circulating water tank is ≤[b7], the circulating water pump (8) is started; when the return water temperature and the temperature of the thermal insulation circulating water tank (9) are both greater than or equal to 10°C, all devices are shut down and enter the standby state.

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