Defrosting control method and device for heat pump water heaters, heat pump water heaters and storage media

Abstract

This application provides a defrosting control method, apparatus, heat pump water heater, and computer-readable storage medium for a heat pump water heater, relating to the field of heat pump water heater technology. The method includes: during the i-th defrosting operation of the heat pump water heater, if a high-pressure switch protection shutdown mechanism is triggered, obtaining a first defrosting duration of the heat pump water heater; during the (i+1)-th defrosting operation of the heat pump water heater, obtaining a second defrosting duration and a first heat exchange temperature, where the first heat exchange temperature is the inlet temperature of the outdoor heat exchanger during the (i+1)-th defrosting operation; before the second defrosting duration reaches the first defrosting duration, determining whether the outdoor fan speed adjustment timing has been reached based on the first defrosting duration, the second defrosting duration, and the first heat exchange temperature; and adjusting the outdoor fan speed when the speed adjustment timing is reached to reduce the high-pressure side pressure of the heat pump water heater. This application can reduce the probability of defrosting operation interruption, ensure the complete execution of the defrosting process, and improve the reliability of defrosting.

Description

Technical Field

[0001] This application relates to the field of heat pump water heater technology, and more specifically, to a defrosting control method, apparatus, heat pump water heater, and computer-readable storage medium for a heat pump water heater. Background Technology

[0002] R454C is an A2L-class refrigerant with a low Global Warming Potential (GWP), significantly lower than high GWP refrigerants (such as R404A and R410A). This aligns with current EU policies on environmentally friendly refrigerants (EU regulations on fluorinated greenhouse gases) and has become an important alternative in the heat pump field. Compared to A3-class highly flammable and explosive refrigerants (such as R290), R454C offers greater safety and allows for higher refrigerant charges in system design, effectively improving heat exchange capacity and heating performance. However, a higher refrigerant charge can lead to a sharp increase in system discharge pressure during the later stages of defrosting in heat pump water heater systems. Especially under low-temperature and high-humidity conditions, the concentrated condensation load and deteriorated heat dissipation during defrosting can easily trigger the high-pressure switch protection, causing shutdown, interrupted defrosting, and frost residue. This not only reduces the subsequent heating efficiency of the system but may also cause problems such as compressor liquid return and frequent start-stop cycles, seriously affecting the stability and reliability of system operation and the user experience. Summary of the Invention

[0003] This application provides a defrosting control method, device, heat pump water heater, and computer-readable storage medium for a heat pump water heater. After a previous defrosting operation is interrupted due to the triggering of a high-pressure switch protection shutdown mechanism, this application reduces the probability of defrosting operation interruption by adjusting the outdoor fan speed in advance during each subsequent defrosting cycle to lower the high-pressure side pressure of the heat pump water heater. This ensures the complete execution of the defrosting process and improves defrosting reliability.

[0004] Firstly, a defrosting control method for a heat pump water heater is provided. This method includes: during the i-th defrosting period of the heat pump water heater, if a high-pressure switch protection shutdown mechanism is triggered, obtaining a first defrosting duration of the heat pump water heater, where the first defrosting duration is the time interval between the start time of the i-th defrosting period and the trigger time of the high-pressure switch protection shutdown mechanism, i≥1; during the (i+1)-th defrosting period of the heat pump water heater, obtaining a second defrosting duration and a first heat exchange temperature, where the first heat exchange temperature is the inlet temperature of the outdoor heat exchanger during the (i+1)-th defrosting period; before the second defrosting duration reaches the first defrosting duration, determining whether the outdoor fan speed adjustment timing has been reached based on the first defrosting duration, the second defrosting duration, and the first heat exchange temperature; and if the speed adjustment timing has been reached, adjusting the outdoor fan speed to reduce the high-pressure side pressure of the heat pump water heater.

[0005] Based on the above technical solution, this application, during the defrosting process of a heat pump water heater, if the high-pressure switch protection shutdown mechanism is triggered, records the time interval from the start of defrosting to shutdown. Then, after the heat pump water heater starts defrosting again, and before the current defrosting duration reaches the aforementioned time interval, it determines whether the outdoor fan speed adjustment timing has been reached based on the aforementioned time interval, the current defrosting duration, and the current inlet temperature of the outdoor heat exchanger. If the timing for speed adjustment is determined to be reached, the outdoor fan speed is adjusted. This proactively reduces the high-pressure side pressure of the heat pump water heater by adjusting the outdoor fan speed before a new defrosting cycle occurs and before a high-pressure risk is detected. This effectively suppresses the rapid rise in high-pressure side pressure, thereby avoiding repeated triggering of the high-pressure switch protection shutdown during the new defrosting cycle. Therefore, this application not only ensures the complete execution of the defrosting process but also significantly improves the reliability of defrosting and avoids systemic risks such as frost residue, decreased heating efficiency, compressor liquid return, and frequent start-stop caused by defrosting interruptions.

[0006] In one possible implementation, adjusting the wind speed of the outdoor fan includes: determining the temperature difference between a first heat exchange temperature and a second heat exchange temperature at preset intervals, wherein the second heat exchange temperature is the inlet temperature of the outdoor heat exchanger when the high-pressure switch protection shutdown mechanism is triggered; and adjusting the wind speed setting of the outdoor fan according to the temperature difference.

[0007] In one possible implementation, adjusting the wind speed of the outdoor fan based on the temperature difference includes: when the temperature difference is greater than or equal to a preset temperature difference, determining the adjustment amount based on the temperature difference; and adjusting the wind speed based on the adjustment amount.

[0008] In one possible implementation, when the wind speed adjustment time is reached, the wind speed of the outdoor fan is adjusted to reduce the high-pressure side pressure of the heat pump water heater. The defrosting control method of the heat pump water heater further includes: during the (i+1)th defrosting period of the heat pump water heater, if the high-pressure switch protection shutdown mechanism is triggered, during the (i+2)th defrosting period of the heat pump water heater, the wind speed level is increased by a preset level increment value at preset intervals.

[0009] In one possible implementation, determining whether the outdoor fan's wind speed adjustment timing has been reached based on the first defrost duration, the second defrost duration, and the first heat exchange temperature includes: if the second defrost duration is greater than or equal to the time difference and the first heat exchange temperature is less than or equal to the first temperature threshold, it is determined that the wind speed adjustment timing has been reached, where the time difference is the difference between the first defrost duration and the time adjustment amount; if the second defrost duration is not greater than or equal to the time difference and the first heat exchange temperature is less than or equal to the first temperature threshold, it is determined that the wind speed adjustment timing has not been reached.

[0010] In one possible implementation, after obtaining the first defrosting duration of the heat pump water heater, the defrosting control method further includes: determining, based on the first water temperature of the heat pump water heater, whether the (i+1)th defrosting of the heat pump water heater occurs during the intermediate heating stage. The intermediate heating stage refers to the stage after the heat pump water heater is restarted following the release of the high-pressure switch protection shutdown until the water temperature reaches the shutdown temperature and then shuts down again. The first water temperature is the water temperature of the heat pump water heater when the high-pressure switch protection shutdown mechanism is triggered. If the (i+1)th defrosting of the heat pump water heater occurs during the intermediate heating stage, the method executes the following: if the second defrosting duration has not reached the first defrosting duration... Before the first defrost duration, determine whether the outdoor fan speed adjustment timing has been reached based on the first defrost duration, the second defrost duration, and the first heat exchange temperature. If the (i+1)th defrost of the heat pump water heater does not occur during the intermediate heating stage, obtain the second water temperature of the heat pump water heater during the (i+1)th defrost period. If the second water temperature is greater than or equal to the water temperature difference, execute the step of determining whether the outdoor fan speed adjustment timing has been reached based on the first defrost duration, the second defrost duration, and the first heat exchange temperature before the second defrost duration reaches the first defrost duration. The water temperature difference is the difference between the first water temperature and the temperature tolerance.

[0011] In one possible implementation, determining whether the (i+1)th defrosting of the heat pump water heater occurs during the intermediate heating stage based on the first water temperature of the heat pump water heater includes: if the first water temperature is greater than or equal to the second temperature threshold, determining that the (i+1)th defrosting of the heat pump water heater did not occur during the intermediate heating stage; if the second water temperature is less than the water temperature difference, determining that the (i+1)th defrosting of the heat pump water heater occurred during the intermediate heating stage.

[0012] Secondly, a defrosting control device for a heat pump water heater is provided, the defrosting control device for the heat pump water heater comprising:

[0013] The first acquisition module is used to acquire the first defrosting duration of the heat pump water heater if the high-pressure switch protection shutdown mechanism is triggered during the i-th defrosting of the heat pump water heater. The first defrosting duration is the time interval between the start time of the i-th defrosting of the heat pump water heater and the trigger time of the high-pressure switch protection shutdown mechanism, i≥1. The second acquisition module is used to acquire the second defrosting duration and the first heat exchange temperature of the heat pump water heater during the (i+1)th defrosting of the heat pump water heater. The first heat exchange temperature is the inlet temperature of the outdoor heat exchanger during the (i+1)th defrosting of the heat pump water heater. The timing judgment module is used to determine whether the outdoor fan speed adjustment timing has been reached before the second defrosting time reaches the first defrosting time, based on the first defrosting time, the second defrosting time, and the first heat exchange temperature. The wind speed control module is used to adjust the wind speed of the outdoor fan when the wind speed adjustment time is reached, so as to reduce the high-pressure side pressure of the heat pump water heater.

[0014] Thirdly, a heat pump water heater is provided, including a memory and a processor. The memory is used to store executable program code, and the processor is used to call and run the executable program code from the memory, causing the heat pump water heater to perform the defrosting control method of the heat pump water heater in the first aspect or any possible implementation thereof.

[0015] Fourthly, a computer program product is provided, comprising: computer program code, which, when executed on a computer, causes the computer to perform the defrosting control method for a heat pump water heater as described in the first aspect or any possible implementation thereof.

[0016] Fifthly, a computer-readable storage medium is provided, which stores computer program code that, when executed on a computer, causes the computer to perform the defrosting control method for a heat pump water heater as described in the first aspect or any possible implementation thereof. Attached Figure Description

[0017] Figure 1 A schematic flowchart of a defrosting control method for a heat pump water heater provided in an embodiment of this application is shown; Figure 2 This application provides a system schematic diagram of a heat pump water heater according to an embodiment of the present application; Figure 3 This paper shows another schematic flowchart of a defrosting control method for a heat pump water heater provided in an embodiment of the present application; Figure 4This paper shows a schematic diagram of the structure of a defrosting control device for a heat pump water heater according to an embodiment of this application; Figure 5 A schematic diagram of the structure of a heat pump water heater provided in an embodiment of this application is shown. Detailed Implementation

[0018] The technical solutions in this application will be clearly and thoroughly described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B. "And / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more than two.

[0019] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0020] R454C is an A2L-class low-GWP refrigerant, significantly lower than high-GWP refrigerants (such as R404A and R410A), aligning with current EU policies on environmentally friendly refrigerants (EU regulations on fluorinated greenhouse gases) and becoming an important alternative in the heat pump field. Compared to A3-class highly flammable and explosive refrigerants (such as R290), R454C offers higher safety and allows for higher refrigerant charges in system design, effectively improving heat exchange capacity and heating performance. However, a higher refrigerant charge can lead to a sharp increase in system discharge pressure during the later stages of defrosting operation in heat pump water heater systems, especially under low-temperature and high-humidity conditions. During defrosting, the concentrated condensing load and deteriorated heat dissipation conditions can easily trigger the high-pressure switch protection, causing shutdown, resulting in defrosting interruption and frost residue. This not only easily reduces the subsequent heating efficiency of the system but may also cause problems such as compressor liquid return and frequent start-stop cycles, seriously affecting the stability and reliability of system operation and the user experience.

[0021] Based on the above problems, this application provides a defrosting control method, device, heat pump water heater, and computer-readable storage medium for a heat pump water heater. During the defrosting process of the heat pump water heater, if the high-pressure switch protection shutdown mechanism is triggered, the application records the time interval from the start of defrosting to shutdown. Then, after the heat pump water heater starts defrosting again, and before the current defrosting duration reaches the aforementioned time interval, the application determines whether the outdoor fan speed adjustment timing has been reached based on the aforementioned time interval, the current defrosting duration, and the current inlet temperature of the outdoor heat exchanger. If the timing for speed adjustment is determined to be reached, the outdoor fan speed is adjusted. This proactively reduces the high-pressure side pressure of the heat pump water heater by adjusting the outdoor fan speed before a new defrosting cycle occurs and before a high-pressure risk is detected. This effectively suppresses the rapid rise of high-pressure side pressure (especially compressor exhaust pressure), thereby avoiding repeated triggering of the high-pressure switch protection shutdown during a new defrosting cycle. Therefore, this application not only ensures the complete execution of the defrosting process, but also significantly improves the reliability of defrosting, and avoids systemic risks such as frost residue, reduced heating efficiency, compressor liquid return, and frequent start-stop caused by defrosting interruption.

[0022] The following is an embodiment of a defrosting control method for a heat pump water heater provided in this application specification.

[0023] Figure 1 A schematic flowchart of a defrosting control method for a heat pump water heater provided in an embodiment of this application is shown, as follows: Figure 1 As shown in the embodiment of this application, the subject of the defrosting control method for a heat pump water heater is the heat pump water heater. Figure 2 This application provides a system schematic diagram of a heat pump water heater according to an embodiment of the present application. Figure 2 As shown, the heat pump water heater includes a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, an electronic expansion valve 4, a water storage tank 5, a high-pressure switch HP, a low-pressure switch LP, etc. The compressor 1, four-way valve 2, outdoor heat exchanger 3, electronic expansion valve 4, water storage tank 5, high-pressure switch HP, low-pressure switch LP, etc., are arranged according to... Figure 2 The connection is shown in the figure. Where Tp represents the exhaust temperature of compressor 1, Th represents the return gas temperature of compressor 1, T4 represents the outdoor ambient temperature, T3 represents the inlet temperature of outdoor heat exchanger 3, T5 represents the temperature of the water tank wall of water storage tank 5, referred to as water temperature, Twin represents the water inlet of water storage tank 5, and Tout represents the water outlet of water storage tank 5.

[0024] Figure 2The defrosting principle of the heat pump water heater is as follows: When the heat pump water heater switches to defrost mode, it performs a defrosting operation. The high-temperature, high-pressure refrigerant vapor discharged from compressor 1 passes through the four-way valve 2 and, instead of entering the indoor heat exchanger in the water tank 5, directly enters the outdoor heat exchanger 3. Once the high-temperature, high-pressure refrigerant vapor enters the outdoor heat exchanger 3, the outdoor heat exchanger 3 acts as a condenser, releasing heat through the high-temperature refrigerant to melt the frost condensed on its surface. After defrosting, the refrigerant passes through the electronic expansion valve 4, then through the indoor heat exchanger in the water tank 5, and finally returns to the compressor, forming a brief refrigeration cycle. This achieves defrosting of the outdoor heat exchanger, thus defrosting the heat pump water heater. During the defrosting process, the opening of the electronic expansion valve 4 is adjusted to its maximum to reduce the resistance to refrigerant flow, thereby reducing system pressure loss.

[0025] The defrosting control method for heat pump water heaters provided in this application includes the following solutions: S110: During the i-th defrost cycle of the heat pump water heater, determine whether the high-pressure switch protection shutdown mechanism has been triggered. If yes, proceed to S120; otherwise, proceed to S160. S120: Obtain the first defrosting duration of the heat pump water heater. The first defrosting duration is the time interval between the start time of the i-th defrosting of the heat pump water heater and the trigger time of the high-pressure switch protection shutdown mechanism, i≥1; S130: During the (i+1)th defrost of the heat pump water heater, obtain the second defrost duration and the first heat exchange temperature of the heat pump water heater. The first heat exchange temperature is the inlet temperature of the outdoor heat exchanger during the (i+1)th defrost of the heat pump water heater. S140: Before the second defrosting time reaches the first defrosting time, determine whether the outdoor fan speed adjustment time has been reached based on the first defrosting time, the second defrosting time, and the first heat exchange temperature. If yes, execute S150; otherwise, continue to execute S140. S150: Adjusts the wind speed of the outdoor fan to reduce the high-pressure side pressure of the heat pump water heater; S160: Exit defrosting when the defrosting exit conditions are met.

[0026] In an exemplary embodiment, the i-th defrost of the heat pump water heater can be understood as the current defrost operation performed by the heat pump water heater, and the (i+1)-th defrost of the heat pump water heater can be understood as the next defrost operation performed by the heat pump water heater. During the i-th defrost of the heat pump water heater, it is determined whether the high-pressure switch protection shutdown mechanism is triggered. For example, the pressure value on the high-pressure side of the heat pump water heater (e.g., the exhaust pressure of the compressor) is obtained. If the pressure value is less than the pressure threshold, the high-pressure switch protection shutdown mechanism is not triggered, and the heat pump water heater is controlled to perform the defrost operation normally. It is also determined in real time whether the defrost exit condition is met. If the defrost exit condition is met, the defrost operation is exited, thereby controlling the heat pump water heater to stop performing the defrost operation. If the water tank needs to be heated, the heat pump water heater is controlled to perform the heating operation. If the pressure value is greater than or equal to the pressure threshold, the high-pressure switch protection shutdown mechanism is triggered, thereby controlling the heat pump water heater to stop. That is, the i-th defrost is interrupted due to the triggering of the high-pressure switch protection shutdown mechanism, and the i-th defrost is incomplete. After the heat pump water heater stops, the time interval between the start time of the i-th defrost and the trigger time of the high-pressure switch protection shutdown mechanism is obtained to obtain the first defrost duration of the i-th defrost. For example, if the i-th defrost is at time t1 and the trigger time of the high-pressure switch protection shutdown mechanism is at time t2, then the first defrost duration = t2 - t1.

[0027] After obtaining the first defrosting time, it becomes the waiting time for the high-pressure switch protection shutdown mechanism to be triggered during the i-th defrosting of the heat pump water heater. In other words, it is the waiting time for the high-pressure risk to occur during the i-th defrosting of the heat pump water heater. The triggering time of the high-pressure switch protection shutdown mechanism is the moment when the high-pressure risk occurs. Therefore, the first defrosting time can be estimated as the waiting time for the high-pressure switch protection shutdown mechanism to be triggered during the (i+1)-th defrosting of the heat pump water heater. That is, the timing starts from the (i+1)-th defrosting of the heat pump water heater. If the timing reaches the first defrosting time, it is highly likely that the high-pressure switch protection shutdown mechanism will also be triggered, thereby interrupting the (i+1)-th defrosting and causing the (i+1)-th defrosting to be incomplete.

[0028] To avoid incomplete defrosting of the heat pump water heater during the (i+1)th defrost cycle, or to reduce the probability of incomplete defrosting during the (i+1)th defrost cycle, it is necessary to proactively reduce the high-pressure side pressure of the heat pump water heater after the (i+1)th defrost cycle begins and before a high-pressure risk occurs during the (i+1)th defrost cycle. This is to prevent the high-pressure switch protection shutdown mechanism from being triggered, which would interrupt the (i+1)th defrost cycle.

[0029] Specifically, when the heat pump water heater stops due to the high-pressure switch protection shutdown mechanism during the i-th defrost, if the defrost command for the (i+1)-th defrost is detected, the heat pump water heater is controlled to start the i-th defrost. Then, the second defrost duration of the heat pump water heater and the inlet temperature of the outdoor heat exchanger during the (i+1)-th defrost (called the first heat exchange temperature) are obtained. Then, before the second defrost duration reaches the first defrost duration, the outdoor fan speed adjustment timing is determined based on the first defrost duration, the second defrost duration, and the first heat exchange temperature. That is, the fan speed adjustment timing is selected before the high-pressure switch protection shutdown mechanism is triggered again.

[0030] Specifically, based on the first defrost duration, the second defrost duration, and the first heat exchange temperature, determining whether the outdoor fan speed adjustment timing has been reached includes: if it is determined that the second defrost duration is greater than or equal to the time difference and the first heat exchange temperature is less than or equal to the first temperature threshold, the timing for speed adjustment has been reached, where the time difference is the difference between the first defrost duration and the time adjustment amount; if it is determined that the second defrost duration is not greater than or equal to the time difference and the first heat exchange temperature is less than or equal to the first temperature threshold, the timing for speed adjustment has not been reached. The condition of the first heat exchange temperature being less than or equal to the first temperature threshold is used as one of the conditions for determining whether the outdoor fan speed adjustment timing has been reached. Its main purpose is to: effectively suppress the rapid rise of high-pressure side pressure by enhancing the heat dissipation capacity of the outdoor heat exchanger while ensuring that the defrosting effect is not affected; at the same time, since the surface temperature of the outdoor heat exchanger is already at a relatively high level at this time, the frost layer on the surface of the outdoor heat exchanger has basically melted, and moderately increasing the fan speed will not cause the refrigerant to become too cold or the surface temperature of the heat exchanger to drop sharply, thereby avoiding the risk of local re-frost formation due to excessive cooling. The main purpose of satisfying the second condition—that the defrosting duration is greater than or equal to the time difference—is to enhance the heat dissipation capacity of the outdoor heat exchanger before the high-pressure risk occurs during the defrosting process of the heat pump water heater, thus actively suppressing the rapid rise of the high-pressure side pressure. Simultaneously, since defrosting has entered the mid-to-late stage and the frost layer on the outdoor heat exchanger surface has largely melted, appropriately increasing the fan speed will not affect the defrosting effect, nor will it cause the surface temperature of the outdoor heat exchanger to drop sharply below the dew point, triggering re-frost formation. This ensures the integrity of defrosting while effectively preventing repeated triggering of the high-pressure switch protection shutdown. Therefore, combining these two conditions to determine when to adjust the fan speed avoids both premature adjustment of the outdoor fan speed, which would reduce the defrosting effect, and delayed reduction of the high-pressure side pressure, which could lead to pressure runaway. This precisely and steadily suppresses the rise of the high-pressure side pressure without sacrificing the defrosting effect, ensuring the complete defrosting process.

[0031] If the wind speed adjustment timing is determined, it means that adjusting the outdoor fan speed at this time will not interfere with the defrosting effect and will effectively reduce the high-pressure side pressure of the heat pump water heater. Therefore, actively adjusting the outdoor fan speed at this time can significantly suppress the rapid rise of the high-pressure side pressure, thereby avoiding triggering the high-pressure switch protection shutdown again during the (i+1)th defrosting process and ensuring the complete execution of this defrosting process.

[0032] Based on the technical solutions formed by S110 to S150 above, this application, during the defrosting process of a heat pump water heater, if the high-pressure switch protection shutdown mechanism is triggered, records the time interval from the start of defrosting to shutdown. Then, after the heat pump water heater starts defrosting again, and before the current defrosting duration reaches the aforementioned time interval, it determines whether the outdoor fan speed adjustment timing has been reached based on the aforementioned time interval, the current defrosting duration, and the current inlet temperature of the outdoor heat exchanger. If the timing for speed adjustment is determined to be reached, the outdoor fan speed is adjusted. This proactively reduces the high-pressure side pressure of the heat pump water heater by adjusting the outdoor fan speed before a new defrosting cycle occurs and before a high-pressure risk is detected. This effectively suppresses the rapid rise in high-pressure side pressure, thereby avoiding repeated triggering of the high-pressure switch protection shutdown during the new defrosting cycle. Therefore, this application not only ensures the complete execution of the defrosting process but also significantly improves the reliability of defrosting and avoids systemic risks such as frost residue, decreased heating efficiency, compressor liquid return, and frequent start-stop caused by defrosting interruptions.

[0033] In one possible implementation, the above-mentioned adjustment of the outdoor fan speed includes the following steps: The temperature difference between the first heat exchange temperature and the second heat exchange temperature is determined once at a preset time interval. The second heat exchange temperature is the inlet temperature of the outdoor heat exchanger when the high-pressure switch protection shutdown mechanism is triggered. Adjust the outdoor fan speed setting according to the temperature difference.

[0034] This application primarily adjusts the outdoor fan speed by changing the fan speed setting. Specifically, it obtains the inlet temperature of the outdoor heat exchanger during the i-th defrost cycle of the heat pump water heater when the high-pressure switch protection shutdown mechanism is triggered, thus obtaining the second heat exchange temperature. Then, during the (i+1)-th defrost cycle of the heat pump water heater, and when it is determined that the timing for fan speed adjustment has arrived, it calculates the temperature difference between the first and second heat exchange temperatures at preset intervals (e.g., 10 seconds), denoted as ΔT3, i.e., ΔT3 = second heat exchange temperature - first heat exchange temperature. Based on the current fan speed setting (e.g., setting 2), it adjusts the outdoor fan speed setting according to the temperature difference, thereby achieving fan speed regulation.

[0035] In one possible implementation, adjusting the wind speed of the outdoor fan based on the temperature difference includes the following steps: when the temperature difference is greater than or equal to a preset temperature difference, determining the adjustment amount based on the temperature difference, and adjusting the wind speed based on the adjustment amount.

[0036] To avoid frequent adjustments to the fan speed setting due to minor temperature fluctuations in a short period of time, this application sets a preset temperature difference as the basis for adjustment. That is, each time the fan speed setting is adjusted, the temperature difference is compared with the preset temperature difference. If the temperature difference is greater than or equal to the preset temperature difference, the fan speed setting can be adjusted. If the temperature difference is less than the preset temperature difference, the fan speed setting cannot be adjusted.

[0037] Once the temperature difference is obtained, if it is determined that the temperature difference is greater than or equal to the preset temperature difference, the gear adjustment amount △STEP is calculated based on the temperature difference △T3. △STEP = △T3 × c, where c is a proportional coefficient used to convert the temperature change into the gear adjustment amount. c > 0, for example, c = 1.

[0038] After obtaining △STEP, the specific gear increase value corresponding to the gear adjustment amount is determined based on whether △STEP is greater than 0. For example, FAN gear = (-1, +2)STEP. If △STEP > 0, the target gear increase value is +2, that is, 2 gears are added to the base gear of the current wind speed of the outdoor fan, that is, the final gear = current wind speed + (+2); if △STEP < 0, the target gear increase value is -1, that is, 1 gear is subtracted from the base gear of the current wind speed of the outdoor fan, that is, the final gear = current wind speed + (-1).

[0039] The adjusted outdoor fan speed is not higher than the first preset speed (e.g., speed 5) or lower than the second preset speed (e.g., speed 1). The outdoor fan speed is adjusted by the temperature difference between the inlet temperature of the outdoor heat exchanger during the i-th defrost period when the high-pressure switch protection shutdown mechanism is triggered and the inlet temperature of the outdoor heat exchanger during the (i+1)-th defrost period. This achieves dynamic adjustment of the outdoor fan speed based on the historical and current inlet temperature trends of the outdoor heat exchanger, preventing defrosting interruptions due to increased high-pressure side pressure in the heat pump water heater without sacrificing defrosting efficiency.

[0040] In one possible implementation, after adjusting the outdoor fan speed to reduce the high-pressure side pressure of the heat pump water heater when the wind speed adjustment timing is reached, the defrosting control method for the heat pump water heater further includes the following steps: If the high-pressure switch protection shutdown mechanism is triggered during the (i+1)th defrost of the heat pump water heater, the fan speed will be increased by the preset increment value at each preset time interval during the (i+2)th defrost of the heat pump water heater.

[0041] During the (i+1)th defrost cycle of the heat pump water heater, if the outdoor fan speed is adjusted, it is determined whether the high-pressure switch protection shutdown mechanism is triggered. If the high-pressure switch protection shutdown mechanism is triggered, the heat pump water heater is stopped. Then, it is checked whether the heat pump water heater has started the (i+2)th defrost cycle. If it is determined that the heat pump water heater has started the (i+2)th defrost cycle, during the (i+2)th defrost cycle when the outdoor fan speed needs to be adjusted, the fan speed is increased by a preset increment (e.g., +1) at preset intervals. This ensures that the fan speed increases once at preset intervals during the (i+2)th defrost cycle, thereby reducing the high-pressure side pressure of the heat pump water heater. This further ensures the smooth progress of the defrost process and avoids defrost interruption due to the high-pressure switch protection shutdown mechanism being triggered again.

[0042] In one possible implementation, after obtaining the first defrosting duration of the heat pump water heater, the defrosting control method for the heat pump water heater further includes the following steps: Based on the first water temperature of the heat pump water heater, determine whether the (i+1)th defrosting of the heat pump water heater occurs during the intermediate heating stage; If the (i+1)th defrosting of the heat pump water heater occurs during the intermediate heating stage, the following steps are executed: before the second defrosting time reaches the first defrosting time, determine whether the outdoor fan speed adjustment timing is reached based on the first defrosting time, the second defrosting time, and the first heat exchange temperature. If the (i+1)th defrosting of the heat pump water heater does not occur during the intermediate heating stage, the second water temperature of the heat pump water heater is obtained during the (i+1)th defrosting of the heat pump water heater. If the second water temperature is greater than or equal to the water temperature difference, the following step is executed: before the second defrost time reaches the first defrost time, determine whether the outdoor fan speed adjustment timing has been reached based on the first defrost time, the second defrost time, and the first heat exchange temperature. The water temperature difference is the difference between the first water temperature and the temperature tolerance.

[0043] After the heat pump water heater is interrupted during the i-th defrost cycle due to the high-pressure switch protection shutdown mechanism, the (i+1)-th defrost cycle may or may not occur during the intermediate heating phase. The intermediate heating phase refers to the period from when the heat pump water heater restarts after the high-pressure switch protection shutdown is lifted until the water temperature reaches the shutdown temperature and then shuts down again. If the (i+1)-th defrost cycle occurs during the intermediate heating phase, it indicates that there was a temperature range crossing before the (i+1)-th defrost cycle; if the (i+1)-th defrost cycle does not occur during the intermediate heating phase, it indicates that there was no temperature range crossing before the (i+1)-th defrost cycle.

[0044] Determining whether the (i+1)th defrost of the heat pump water heater occurs during the intermediate heating stage based on the first water temperature of the heat pump water heater includes: if the first water temperature is greater than or equal to the second temperature threshold, it is determined that the (i+1)th defrost of the heat pump water heater did not occur during the intermediate heating stage; if the second water temperature is less than the water temperature difference, it is determined that the (i+1)th defrost of the heat pump water heater occurred during the intermediate heating stage.

[0045] The first water temperature is the water temperature of the heat pump water heater during the i-th defrost period, when the high-pressure switch protection shutdown mechanism is triggered. Let the first water temperature be denoted as T5a, and the second temperature threshold be denoted as x. Compare T5a and x. If T5a ≥ x, it means that the water temperature of the heat pump water heater during the i-th defrost period, when the high-pressure switch protection shutdown mechanism is triggered, is close to the water temperature reaching the shutdown point. That is, the temperature difference between T5a and the preset shutdown water temperature (e.g., 65℃) is very small, and no further defrosting process will occur during the remaining heating stage (e.g., heating to 65℃). After the heat pump water heater reaches its operating temperature and shuts down, it needs to wait for the next heating cycle (i.e., the new heating cycle). During this new heating cycle, the actual water temperature in the storage tank will be much lower than T5a. For example, if T5a = 45℃, the actual water temperature in the storage tank will be 20℃. This means that the (i+1)th defrost occurs within this new heating cycle. Therefore, it is assumed that when T5a ≥ x, the (i+1)th defrost of the heat pump water heater will not occur after the heat pump water heater is deactivated by the high-pressure switch protection and shut down, and then restarted until the water temperature reaches the shutdown temperature. Instead, it will occur during the stage when the heat pump water heater restarts to heat water after reaching the shutdown temperature. Therefore, it is assumed that the (i+1)th defrost of the heat pump water heater does not occur during the intermediate heating stage. Thus, it can be determined that there is a cross-temperature range before the (i+1)th defrost of the heat pump water heater.

[0046] If T5a < x, it means that during the i-th defrost period of the heat pump water heater, and when the high-pressure switch protection shutdown mechanism is triggered, the water temperature is low, and the temperature difference between it and the set shutdown water temperature (e.g., 65℃) is large. After the high-pressure switch protection is released and the heat pump water heater is restarted, the heat pump water heater will continue to heat up within the same heating cycle and re-enter the defrost stage during the water temperature rise. That is, after the high-pressure switch protection is released and the heat pump water heater is restarted, the actual water temperature in the storage tank will not be much lower than T5a, but will be close to T5a. After a short period of heating, the actual water temperature in the storage tank will gradually rise based on T5a and re-enter the defrost stage during the water temperature rise. That is, the (i+1)-th defrost occurs during this heating process (that is, the heating process after the high-pressure switch protection is released and the heat pump water heater is restarted). Therefore, it is considered that the (i+1)-th defrost of the heat pump water heater occurs in the middle heating stage. Thus, it can be determined that there is no cross-temperature range before the (i+1)-th defrost of the heat pump water heater.

[0047] If it is determined that the (i+1)th defrost of the heat pump water heater occurs during the intermediate heating phase (i.e., there is no temperature range crossing before the (i+1)th defrost), and the (i+1)th defrost occurs after the heat pump water heater is deactivated by the high-pressure switch protection shutdown and restarted until the water temperature reaches the shutdown temperature, then the actual water temperature in the storage tank does not increase significantly during this phase, but rather increases slowly. The system heat load is relatively stable, and the frost melting conditions are controllable. Therefore, once it is determined that the (i+1)th defrost of the heat pump water heater occurs during the intermediate heating phase, the process directly executes the step of determining whether the outdoor fan speed adjustment timing has been reached based on the first defrost time, the first defrost time, the second defrost time, and the first heat exchange temperature, before the second defrost time reaches the first defrost time. This allows for rapid intervention in adjusting the outdoor fan speed to suppress the rise in high-pressure side pressure and prevent the high-pressure switch protection shutdown from triggering again, thus avoiding defrosting interruption.

[0048] If it is determined that the (i+1)th defrost of the heat pump water heater did not occur during the intermediate heating phase (i.e., there was a temperature range before the (i+1)th defrost), then the (i+1)th defrost of the heat pump water heater occurs within the new heating cycle. Since the actual water temperature in the storage tank needs to rise from a relatively low temperature (20℃) at the start of the new heating cycle, and the temperature difference from T5a is relatively large, the system will not trigger the (i+1)th defrost prematurely. Therefore, during the (i+1)th defrost, it is necessary to obtain the current water temperature of the heat pump water heater to obtain the second water temperature; then compare the second water temperature with the water temperature difference, which is the difference between the first water temperature and the temperature tolerance. If the second water temperature is greater than or equal to the water temperature difference, it indicates that the current water temperature of the heat pump water heater is about to approach the water temperature at which the high-pressure switch protection shutdown mechanism was triggered during the (i)th defrost. Therefore, once the second water temperature is detected to be greater than or equal to the water temperature difference, the system will take appropriate action. If the water temperature difference is equal to or greater than the first defrost time, the process immediately begins. Before the second defrost time reaches the first defrost time, the process determines whether the outdoor fan speed adjustment is appropriate based on the first defrost time, the second defrost time, and the first heat exchange temperature. This ensures timely intervention to adjust the outdoor fan speed, suppressing the rise in high-pressure side pressure and preventing the high-pressure switch protection from triggering again and interrupting defrosting. Conversely, it avoids premature intervention, which could lead to excessive heat loss during the initial defrosting phase, causing the outdoor heat exchanger's surface temperature to drop too quickly, affecting frost melting, and even risking localized re-frost formation. By using the second water temperature difference as the criterion, the process precisely initiates fan speed adjustment within the time window when high-pressure risk is approaching but defrosting needs can still be met. This achieves effective suppression of high-pressure side pressure while maintaining defrosting effectiveness, ensuring complete and stable defrosting execution.

[0049] The following is another embodiment of a defrosting control method for a heat pump water heater provided in this application specification.

[0050] For a heat pump water heater where there is a cross-temperature range before the (i+1)th defrost, this application represents the first defrost duration as ta, the second heat exchange temperature as T3a, the first water temperature as T5a, the second defrost duration as tc, the second heat exchange temperature as T3c, the second water temperature as T5c, the time adjustment amount as k1, the first temperature threshold as k2, and the temperature tolerance as k3. The time difference = ta - k1, and the water temperature difference = T5a - k3. For a heat pump water heater where there is no cross-temperature range before the (i+1)th defrost, this application represents the first defrost duration as ta, the second heat exchange temperature as T3a, the first water temperature as T5a, the second defrost duration as tb, the second heat exchange temperature as T3b, the time adjustment amount as k1, the second temperature threshold as k2, and the time difference = ta - k1.

[0051] To more clearly explain the values ​​of the parameters k1 to k3 and x, please refer to Table 1 for details on how the parameters k1 to k3 and x should be selected.

[0052] Table 1

[0053] Figure 3 Another schematic flowchart of a defrosting control method for a heat pump water heater provided in an embodiment of this application is shown, such as... Figure 3 As shown in the embodiments of this application, a defrosting control method for a heat pump water heater includes the following solutions: S210: The heat pump water heater is performing a defrosting operation for the i-th time; S211: Determine whether the high-voltage switch protection shutdown mechanism has been triggered. If yes, execute S212; otherwise, execute S250. S212: Obtain ta, T5a, and T3a when the high-voltage switch protection shutdown mechanism is triggered; S213: Determine if T5a≥x; if yes, execute S220; otherwise, execute S230. S220: If it is detected that the heat pump water heater has restarted after the high-pressure switch protection is released, and then it is detected that the heat pump water heater has stopped after reaching the temperature and restarted again, obtain T5c; S221: Determine if T5c ≥ T5a-k3; if yes, execute S222; otherwise, execute S220. S222: Upon detecting that the heat pump water heater has started the (i+1)th defrost cycle, obtain tc; S223: Determine if tc ≥ ta - k1; if yes, execute S224; otherwise, execute S222. S224: Obtain T3c; S225: Determine if T3c≥k2; if yes, execute S226; otherwise, execute S224. S226: Calculate △T3, adjust the outdoor fan speed according to △T3 to reduce the high-pressure side pressure of the heat pump water heater, △T3=T3a-T3c, and execute S240; S230: Upon detecting that the heat pump water heater has restarted after the high-pressure switch protection has been released and the (i+1)th defrost cycle has begun, tb is obtained; S231: Determine if tb ≥ ta - k1; if yes, execute S232; otherwise, execute S230. S232: Obtain T3b; S233: Determine if T3b≥k2; if yes, execute S234; otherwise, continue executing S232. S234: Calculate △T3, adjust the outdoor fan speed setting according to △T3 to reduce the high-pressure side pressure of the heat pump water heater, △T3=T3a-T3b, and execute S240; S240: Determine whether the high-voltage switch protection shutdown mechanism is triggered during the (i+1)th defrosting. If yes, execute S241; otherwise, execute S250. S241: During the (i+2)th defrosting of the heat pump water heater, the fan speed is increased by a preset increment value at preset intervals, and S211 is executed. S250: Defrosting will be discontinued when the defrosting discontinuation conditions are met.

[0054] The technical solution formed by S210 to S250 described above can reduce the probability of defrosting operation interruption after the first defrosting of the heat pump water heater is interrupted due to the high-pressure switch protection shutdown mechanism. In subsequent defrosting operations, the outdoor fan speed can be adjusted in advance to reduce the high-pressure side pressure of the heat pump water heater, thereby ensuring the complete execution of the defrosting process and improving the reliability of defrosting.

[0055] The following are embodiments of the apparatus described in this application, which can be used to execute the embodiments of the method described in this application. For details not disclosed in the apparatus embodiments of this application, please refer to the embodiments of the method described in this application.

[0056] Figure 4 This application provides a schematic diagram of the structure of a defrosting control device for a heat pump water heater, as shown in an embodiment. Figure 4 As shown, the defrosting control device 400 of the heat pump water heater includes: The first acquisition module 410 is used to acquire the first defrosting duration of the heat pump water heater if the high-pressure switch protection shutdown mechanism is triggered during the i-th defrosting of the heat pump water heater. The first defrosting duration is the time interval between the start time of the i-th defrosting of the heat pump water heater and the trigger time of the high-pressure switch protection shutdown mechanism, i≥1. The second acquisition module 420 is used to acquire the second defrosting duration and the first heat exchange temperature of the heat pump water heater during the (i+1)th defrosting of the heat pump water heater. The first heat exchange temperature is the inlet temperature of the outdoor heat exchanger during the (i+1)th defrosting of the heat pump water heater. The timing judgment module 430 is used to determine whether the timing for adjusting the wind speed of the outdoor fan has been reached before the second defrosting time reaches the first defrosting time, based on the first defrosting time, the second defrosting time, and the first heat exchange temperature. The wind speed control module 440 is used to adjust the wind speed of the outdoor fan when the wind speed adjustment time is reached, so as to reduce the high-pressure side pressure of the heat pump water heater.

[0057] In one possible implementation, the wind speed control module 440 is specifically used to determine the temperature difference between the first heat exchange temperature and the second heat exchange temperature at preset intervals, wherein the second heat exchange temperature is the inlet temperature of the outdoor heat exchanger when the high-pressure switch protection shutdown mechanism is triggered; and to adjust the wind speed of the outdoor fan according to the temperature difference.

[0058] In one possible implementation, the wind speed control module 440 is specifically used to determine the gear adjustment amount based on the temperature difference when the temperature difference is greater than or equal to a preset temperature difference; and to adjust the wind speed gear based on the gear adjustment amount.

[0059] In one possible implementation, when the wind speed adjustment time is reached, the wind speed of the outdoor fan is adjusted to reduce the high-pressure side pressure of the heat pump water heater. Specifically, during the (i+1)th defrost of the heat pump water heater, if the high-pressure switch protection shutdown mechanism is triggered, the wind speed level is increased by a preset level increment value at preset intervals during the (i+2)th defrost of the heat pump water heater.

[0060] In one possible implementation, the timing judgment module 430 is specifically used to determine that the wind speed adjustment timing has been reached if the second defrosting duration is greater than or equal to the time difference and the first heat exchange temperature is less than or equal to the first temperature threshold, where the time difference is the difference between the first defrosting duration and the time adjustment amount; if the second defrosting duration is not greater than or equal to the time difference and the first heat exchange temperature is less than or equal to the first temperature threshold, it is determined that the wind speed adjustment timing has not been reached.

[0061] In one possible implementation, the timing judgment module 430 is specifically used to determine, based on the first water temperature of the heat pump water heater, whether the (i+1)th defrost of the heat pump water heater occurs during the intermediate heating stage. The intermediate heating stage refers to the period after the heat pump water heater restarts after the high-pressure switch protection shutdown is released, until the water temperature reaches the shutdown temperature and shuts down again. The first water temperature is the water temperature of the heat pump water heater when the high-pressure switch protection shutdown mechanism is triggered. If the (i+1)th defrost of the heat pump water heater occurs during the intermediate heating stage, before the second defrost duration reaches the first defrost duration, the timing judgment module 430 is used to determine, based on the first defrost temperature, whether the (i+1)th defrost of the heat pump water heater occurs during the intermediate heating stage. The steps include: determining whether the outdoor fan speed adjustment timing has been reached based on the first defrost duration, the second defrost duration, and the first heat exchange temperature; if the (i+1)th defrost of the heat pump water heater does not occur during the intermediate heating stage, the second water temperature of the heat pump water heater is obtained during the (i+1)th defrost of the heat pump water heater; if the second water temperature is greater than or equal to the water temperature difference, the steps include: determining whether the outdoor fan speed adjustment timing has been reached based on the first defrost duration, the second defrost duration, and the first heat exchange temperature before the second defrost duration reaches the first defrost duration, where the water temperature difference is the difference between the first water temperature and the temperature tolerance.

[0062] In one possible implementation, the timing judgment module 430 is specifically used to determine that if the first water temperature is greater than or equal to the second temperature threshold, the (i+1)th defrost of the heat pump water heater did not occur in the intermediate heating stage; and if the second water temperature is less than the water temperature difference, the (i+1)th defrost of the heat pump water heater occurred in the intermediate heating stage.

[0063] It should be noted that the defrosting control device for heat pump water heaters provided in the above embodiments is only illustrated by the division of the above functional modules when executing the defrosting control method for heat pump water heaters. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the equipment can be divided into different functional modules to complete all or part of the functions described above. In addition, the defrosting control device for heat pump water heaters provided in the above embodiments and the defrosting control method embodiments for heat pump water heaters belong to the same concept. Therefore, for details not disclosed in the device embodiments of this application, please refer to the embodiments of the defrosting control method for heat pump water heaters described above in this application, which will not be repeated here.

[0064] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0065] Figure 5 This application provides a schematic diagram of the structure of a heat pump water heater according to an embodiment of the present application. Figure 5 As shown, the heat pump water heater 500 includes a memory 501 and a processor 502. The memory 501 stores executable program code 5011, and the processor 502 is used to call and execute the executable program code 5011 to perform a defrosting control method for the heat pump water heater.

[0066] This embodiment can divide the heat pump water heater into functional modules according to the above method example. For example, each function can be assigned to a separate module, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware. It should be noted that the module division in this embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0067] When each function is divided into modules corresponding to its specific function, the heat pump water heater may include: a first acquisition module, a second acquisition module, a timing judgment module, a fan speed control module, etc. It should be noted that all relevant content of each step involved in the above method embodiments can be referenced from the functional descriptions of the corresponding modules, and will not be repeated here.

[0068] The heat pump water heater provided in this embodiment is used to execute the above-described defrosting control method for heat pump water heaters, and thus can achieve the same effect as the above-described implementation method.

[0069] When using integrated units, a heat pump water heater may include a processing module and a storage module. The processing module is used to control and manage the operation of the heat pump water heater. The storage module supports the heat pump water heater in executing relevant program code and data.

[0070] The processing module may be a processor or a controller, which can implement or execute the various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of this application. The processor may also be a combination of functions that implement computing capabilities, such as a combination of one or more microprocessors, a combination of digital signal processing (DSP) and a microprocessor, etc., and the storage module may be a memory.

[0071] This embodiment also provides a computer-readable storage medium storing computer program code. When the computer program code is run on a computer, the computer executes the above-described related method steps to implement a defrosting control method for a heat pump water heater in the above embodiment.

[0072] This embodiment also provides a computer program product that, when run on a computer, causes the computer to perform the aforementioned steps to implement a defrosting control method for a heat pump water heater as described in the above embodiment.

[0073] In addition, the heat pump water heater provided in the embodiments of this application may specifically be a chip, component or module. The heat pump water heater may include a connected processor and a memory. The memory is used to store instructions. When the heat pump water heater is running, the processor can call and execute the instructions to make the chip execute a defrosting control method for a heat pump water heater in the above embodiments.

[0074] In this embodiment, the heat pump water heater, computer-readable storage medium, computer program product or chip are all used to execute the corresponding heat pump water heater defrosting control method provided above. Therefore, the beneficial effects that can be achieved can be referred to the beneficial effects in the corresponding heat pump water heater defrosting control method provided above, and will not be repeated here.

[0075] Through the above description of the embodiments, those skilled in the art will understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0076] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0077] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A defrosting control method for a heat pump water heater, characterized by, The defrosting control method of the heat pump water heater comprises: during the i-th defrosting of the heat pump water heater, if a high-pressure switch protection shutdown mechanism is triggered, a first defrosting duration of the heat pump water heater is obtained, the first defrosting duration being a time interval between a starting time of the i-th defrosting of the heat pump water heater and a triggering time of the high-pressure switch protection shutdown mechanism, i≥1; during the i+1-th defrosting of the heat pump water heater, a second defrosting duration of the heat pump water heater and a first heat exchange temperature are obtained, the first heat exchange temperature being an inlet temperature of an outdoor heat exchanger during the i+1-th defrosting of the heat pump water heater; before the second defrosting duration reaches the first defrosting duration, whether a wind speed adjustment opportunity of an outdoor fan is reached is determined according to the first defrosting duration, the second defrosting duration and the first heat exchange temperature; if the wind speed adjustment opportunity is reached, a wind speed of the outdoor fan is adjusted to reduce a high-pressure side pressure of the heat pump water heater.

2. The defrost control method for a heat pump water heater of claim 1, wherein, The adjustment of the wind speed of the outdoor fan comprises: a temperature difference between the first heat exchange temperature and a second heat exchange temperature is determined every interval of a preset duration, the second heat exchange temperature being an inlet temperature of the outdoor heat exchanger when the high-pressure switch protection shutdown mechanism is triggered; a wind speed gear of the outdoor fan is adjusted according to the temperature difference.

3. The defrost control method for a heat pump water heater of claim 2, wherein, The adjustment of the wind speed gear of the outdoor fan according to the temperature difference comprises: if the temperature difference is greater than or equal to a preset temperature difference, a gear adjustment amount is determined according to the temperature difference; the wind speed gear is adjusted according to the gear adjustment amount.

4. The defrost control method for a heat pump water heater of claim 3, wherein, After the wind speed of the outdoor fan is adjusted to reduce the high-pressure side pressure of the heat pump water heater if the wind speed adjustment opportunity is reached, the defrosting control method of the heat pump water heater further comprises: during the i+1-th defrosting of the heat pump water heater, if the high-pressure switch protection shutdown mechanism is triggered, every interval of the preset duration, the wind speed gear is increased by a preset gear increase value during the i+2-th defrosting of the heat pump water heater.

5. The defrost control method for a heat pump water heater of claim 1, wherein, The determination of whether the wind speed adjustment opportunity of the outdoor fan is reached according to the first defrosting duration, the second defrosting duration and the first heat exchange temperature comprises: if the second defrosting duration is greater than or equal to a time difference value and the first heat exchange temperature is less than or equal to a first temperature threshold, it is determined that the wind speed adjustment opportunity is reached, the time difference value being a difference between the first defrosting duration and a time adjustment amount; if the second defrosting duration is not greater than or equal to the time difference value and the first heat exchange temperature is not less than or equal to the first temperature threshold, it is determined that the wind speed adjustment opportunity is not reached.

6. The defrost control method for a heat pump water heater of claim 1, wherein, After the first defrosting duration of the heat pump water heater is obtained, the defrosting control method of the heat pump water heater further comprises: whether the i+1-th defrosting of the heat pump water heater occurs in an intermediate heating stage is determined according to a first water temperature of the heat pump water heater, the intermediate heating stage being a stage in which the heat pump water heater is restarted after the high-pressure switch protection shutdown is removed until the water temperature reaches a shutdown water temperature and the heat pump water heater is stopped again, the first water temperature being a water temperature of the heat pump water heater when the high-pressure switch protection shutdown mechanism is triggered. if the i+1th defrosting of the heat pump water heater occurs in the intermediate heating stage, the step of determining whether the wind speed adjustment time of the outdoor fan is reached according to the first defrosting time, the second defrosting time and the first heat exchange temperature before the second defrosting time reaches the first defrosting time is performed; if the i+1th defrosting of the heat pump water heater does not occur in the intermediate heating stage, a second water temperature of the heat pump water heater is obtained during the i+1th defrosting of the heat pump water heater; if the second water temperature is greater than or equal to a water temperature difference value, the water temperature difference value being a difference between the first water temperature and a temperature tolerance, the step of determining whether the wind speed adjustment time of the outdoor fan is reached according to the first defrosting time, the second defrosting time and the first heat exchange temperature before the second defrosting time reaches the first defrosting time is performed.

7. The defrost control method for a heat pump water heater of claim 6, wherein, The step of determining whether the i+1th defrosting of the heat pump water heater occurs in the intermediate heating stage according to the first water temperature of the heat pump water heater comprises: if the first water temperature is greater than or equal to a second temperature threshold, it is determined that the i+1th defrosting of the heat pump water heater does not occur in the intermediate heating stage; if the second water temperature is less than the water temperature difference value, it is determined that the i+1th defrosting of the heat pump water heater occurs in the intermediate heating stage.

8. A defrosting control device for a heat pump water heater, comprising: The defrosting control device of the heat pump water heater comprises: a first obtaining module, configured to obtain a first defrosting time of the heat pump water heater during the i th defrosting of the heat pump water heater if a high-pressure switch protection shutdown mechanism is triggered, the first defrosting time being a time interval between a start time of the i th defrosting of the heat pump water heater and a triggering time of the high-pressure switch protection shutdown mechanism, i≥1; a second obtaining module, configured to obtain a second defrosting time and a first heat exchange temperature of the heat pump water heater during the i+1th defrosting of the heat pump water heater, the first heat exchange temperature being an inlet temperature of an outdoor heat exchanger during the i+1th defrosting of the heat pump water heater; a time judgment module, configured to determine whether the wind speed adjustment time of the outdoor fan is reached according to the first defrosting time, the second defrosting time and the first heat exchange temperature before the second defrosting time reaches the first defrosting time; a wind speed control module, configured to adjust the wind speed of the outdoor fan to reduce the high-pressure side pressure of the heat pump water heater if the wind speed adjustment time is reached.

9. A heat pump water heater, characterized by, The heat pump water heater comprises: a memory, configured to store executable program codes; a processor, configured to call and run the executable program codes from the memory, so that the heat pump water heater performs the defrosting control method of the heat pump water heater according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program, when the computer program is executed, the defrosting control method of the heat pump water heater according to any one of claims 1 to 7 is realized.

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