Defrosting method of heat pump machine, controller and heat pump machine

Abstract

The invention discloses a defrosting method of a heat pump machine, a controller and the heat pump machine. The defrosting method comprises the steps that refrigerant circulation of a heat pump machine is controlled to be in refrigeration circulation, and a compressor operates for a preset duration at the starting frequency; the outlet temperature of the evaporator is obtained, and whether the outlet temperature reaches the target temperature is judged; if the outlet temperature reaches the target temperature, defrosting is completed; if the outlet temperature does not reach the target temperature, adjusting a preset duration based on the outlet temperature to obtain a corrected duration; and the compressor is controlled to rise the frequency within the corrected duration and operate at the frequency after frequency rise, and the steps of obtaining the outlet temperature of the evaporator and judging whether the outlet temperature reaches the target temperature or not are executed. According to the defrosting method, the problem that high-pressure protection is triggered when the heat pump machine is defrosted can be reduced, and defrosting is more stable and more sufficient.

Description

Technical Field

[0001] The present application relates to the technical field of defrosting control of heat pump machines, and particularly to a defrosting method, a controller and a heat pump machine for a heat pump machine. Background Art

[0002] A heat pump machine can absorb heat from the outdoor environment through the circulation of refrigerant and transfer it indoors, which can reduce the heating energy consumption and improve the heating energy consumption ratio. When the heat pump machine operates in a low-temperature environment, the outdoor evaporator is prone to frosting, so the heat pump machine needs to be defrosted regularly. A related technology proposes a defrosting method for a heat pump machine. In the related technology, the heat pump machine is prone to trigger high-pressure protection and shut down during defrosting, so the defrosting effect is not ideal. Summary of the Invention

[0003] The main technical problem to be solved by the present application is to provide a defrosting method, a controller and a heat pump machine for a heat pump machine, so that the pressure is more stable during defrosting of the heat pump machine, the defrosting can be more sufficient, and the defrosting effect can be improved.

[0004] To solve the above technical problem, the technical solution adopted by the present application is to provide a defrosting method for a heat pump machine, and the defrosting method includes: controlling the refrigerant circulation of the heat pump machine to be in a refrigeration cycle, and enabling the compressor to operate at a starting frequency for a preset duration; obtaining the outlet temperature of the evaporator, and judging whether the outlet temperature reaches a target temperature; if the outlet temperature reaches the target temperature, the defrosting is completed; if the outlet temperature does not reach the target temperature, adjusting the preset duration based on the magnitude of the outlet temperature to obtain a corrected duration; controlling the compressor to increase the frequency within the corrected duration and maintain the operation at the increased frequency, and executing the steps of obtaining the outlet temperature of the evaporator and judging whether the outlet temperature reaches the target temperature.

[0005] In a possible implementation manner, the step of controlling the compressor to increase the frequency specifically includes: if the outlet temperature does not reach the target temperature, increasing the operating frequency of the compressor by a rated compensation frequency.

[0006] In a possible implementation manner, the step of adjusting the preset duration based on the magnitude of the outlet temperature to obtain a corrected duration specifically includes: judging whether the outlet temperature is greater than a threshold temperature, where the threshold temperature is less than the target temperature; if the outlet temperature is not greater than the threshold temperature, controlling the corrected duration to be the preset duration; if the outlet temperature is greater than the threshold temperature, compensating the preset duration to obtain a corrected duration.

[0007] In a possible implementation, the step of compensating the preset duration to obtain a corrected duration when the outlet temperature is greater than the threshold temperature specifically includes: calculating a compensation duration, and increasing the preset duration by the compensation duration to obtain the corrected duration; wherein, the step of calculating the compensation duration specifically includes: determining whether it is the first time to calculate the compensation duration; if it is the first time to calculate the compensation duration, the calculation formula for the compensation duration is: t = (T m - T 3 ) * A; where t is the compensation duration, T m is the outlet temperature, T 3 is the threshold temperature, and A is a compensation coefficient; if it is not the first time to calculate the compensation duration, the calculation formula for the compensation duration is: t = (T N - T N-1 ) * A; where T N is the outlet temperature obtained this time, and T N-1 is the outlet temperature obtained last time.

[0008] In a possible implementation, control the compressor to increase its frequency at a rated frequency increase acceleration; The step of controlling the compressor to increase its frequency within the corrected duration and maintain operation at the frequency after frequency increase specifically includes: the sum of the frequency increase time of the compressor and the time of operating at the frequency after frequency increase of the compressor is the corrected duration.

[0009] In a possible implementation, the step of controlling the compressor to increase its frequency within the corrected duration and maintain operation at the frequency after frequency increase specifically includes: in response to the frequency of the compressor reaching the defrost threshold frequency during frequency increase, stop frequency increase and control the compressor to operate at the defrost threshold frequency.

[0010] In a possible implementation, the step of completing defrosting when the outlet temperature reaches the target temperature specifically includes: if the outlet temperature reaches the target temperature, continuously detect the outlet temperature; in response to the outlet temperature reaching the target temperature and lasting for a target duration, defrosting is completed.

[0011] In a possible implementation, the defrosting method further includes: in response to the defrosting duration reaching the preset duration, defrosting is completed.

[0012] To solve the above technical problems, another technical solution adopted by this application is to provide a controller. The controller controls the defrosting of the heat pump by the above defrosting method. The controller includes: a control module for controlling the refrigerant cycle of the heat pump to be in the refrigeration cycle, so that the compressor operates at the starting frequency for a preset duration; an acquisition module for acquiring the outlet temperature of the evaporator; a judgment module for judging whether the outlet temperature reaches the target temperature. If the outlet temperature reaches the target temperature, the control module controls the completion of defrosting. If the outlet temperature does not reach the target temperature, the control module adjusts the preset duration based on the magnitude of the outlet temperature to obtain a corrected duration, controls the compressor to increase the frequency within the corrected duration and maintain the increased frequency, and executes the steps of acquiring the outlet temperature of the evaporator and judging whether the outlet temperature reaches the target temperature.

[0013] To solve the above technical problems, another technical solution adopted by this application is to provide a heat pump, and the heat pump controls defrosting by the above defrosting method.

[0014] The beneficial effects of this application are as follows: Different from the prior art, this application provides a defrosting method for a heat pump. This defrosting method controls the compressor to start running at the starting frequency, and the starting frequency is a relatively low operating frequency, so there will be no problem of sudden increase in refrigerant flow. Therefore, it can reduce the problem of triggering high-voltage protection of the heat pump and shutting down, and make the defrosting sufficient. In addition, this application obtains the outlet temperature of the evaporator, adjusts the preset duration according to the outlet temperature to obtain a corrected duration, and can make the compressor run at a low frequency for a short duration and at a high frequency for a long duration according to the defrosting state. The above dynamically adjusts the running duration of the compressor at different frequencies according to the environment, which can improve the defrosting efficiency and reduce the overpressure problem of the heat pump during defrosting. Description of the Drawings

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0016] Figure 1 It is a schematic structural diagram of an embodiment of the heat pump provided by this application; Figure 2 It is a schematic flowchart of an embodiment of the defrosting method of the heat pump of this application; Figure 3 is Figure 2 A schematic flowchart of an embodiment of adjusting the preset duration based on the magnitude of the outlet temperature to obtain a corrected duration; Figure 4 Yes Figure 3 It is a schematic flowchart of a method for compensating a preset duration to obtain a corrected duration in one embodiment; Figure 5 It is a structural block diagram of one embodiment of the controller of the present application.

[0017] Among them, 11 is a four-way valve; 12 is a compressor; 13 is an evaporator; 14 is a condenser; 15 is a throttle valve; 100 is a controller; 200 is a control module; 300 is an acquisition module; 400 is a judgment module. Specific embodiments

[0018] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0019] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "the" and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless clearly stated otherwise in the context. "Plural" generally includes at least two, but does not exclude the case of including at least one.

[0020] It should be understood that the term " / or" used herein is only a description of the associated relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0021] It should be understood that the term "including", "comprising" or any other variant used herein is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, the elements defined by the statement "including..." do not exclude the existence of additional identical elements in the process, method, article or device including the said elements.

[0022] In the related art, when a heat pump defrosts, the compressor enters the defrosting frequency, which is a relatively high operating frequency. Therefore, at the beginning of defrosting, the refrigerant flow rate suddenly increases. The sudden increase in flow rate easily causes the pressure in the pipeline to exceed the threshold, triggering the high-pressure protection of the heat pump and shutting down. Especially in a low-temperature and low-humidity environment, when there is thin or no frost on the evaporator, the refrigerant flow rate is more likely to trigger high-pressure problems after the sudden increase, resulting in incomplete defrosting. On the other hand, in different environments such as low-temperature and high-humidity and low-temperature and low-humidity, the outlet temperature of the outdoor evaporator may be the same, but the frost layer thickness is different. The related art can only control the compressor to defrost at a fixed frequency value, and the fixed frequency cannot meet the defrosting requirements for different frost layer thicknesses.

[0023] Based on the above problems, the present application proposes a defrosting method, a controller and a heat pump for a heat pump. On the one hand, it can reduce the problem that the heat pump triggers high-pressure protection and shuts down when the pipeline pressure exceeds the threshold during defrosting. On the other hand, it can also meet the defrosting requirements for different frost layer thicknesses.

[0024] The following describes in detail a defrosting method, a controller and a heat pump provided by the present application with reference to the drawings and embodiments.

[0025] The present application provides a defrosting method for a heat pump, which is used to defrost the evaporator outside the heat pump. Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of an embodiment of a heat pump provided by the present application. In a specific embodiment, the heat pump (not labeled) includes a four-way valve 11, a compressor 12, a throttle valve 15, an evaporator 13 located outdoors, and a condenser 14 located indoors.

[0026] Among them, the compressor 12 is used to compress the low-temperature and low-pressure gaseous refrigerant to turn it into a high-temperature and high-pressure gaseous refrigerant. The four-way valve 11 is used to switch states and change the flow direction of the refrigerant, playing a role in switching the refrigeration and heating modes in the heat pump. When the refrigerant cycle is in the refrigeration cycle, the four-way valve 11 makes the refrigerant flow to the evaporator 13. When the refrigerant cycle is in the heating cycle, the four-way valve 11 changes the internal connection state, so that the refrigerant first flows through the condenser 14 and then flows to the evaporator 13.

[0027] In the refrigeration mode, the refrigerant circulates in the following order: compressor 12 (exhaust) → four-way valve 11 (towards the evaporator 13) → evaporator 13 → throttle valve 15 → condenser 14 → four-way valve 11 (towards the condenser 14) → compressor 12 (suction).

[0028] In the heating mode, the four-way valve 11 changes direction, making the refrigerant circulate in the following order: compressor 12 (exhaust) → four-way valve 11 (condenser 14 flow path) → condenser 14 → throttle valve 15 → evaporator 13 → four-way valve 11 (evaporator 13 flow path) → compressor 12 (suction).

[0029] As described above, when the refrigerant cycle of the heat pump is controlled to be a refrigeration cycle, the refrigerant in the evaporator 13 flows in a high-temperature and high-pressure state, so that the defrosting purpose can be achieved.

[0030] In some embodiments, the heat pump in the embodiments of the present application further includes a controller (not labeled), and the controller is connected to the compressor 12, the four-way valve 11, etc. of the heat pump. The execution subject of the defrosting method of the heat pump in this embodiment is the controller.

[0031] To reduce the problem that the heat pump triggers high-pressure protection and shuts down during defrosting, to make the defrosting of the evaporator 13 of the heat pump more sufficient, and to meet the defrosting requirements for different thicknesses of frost layers in different environments such as low temperature and high humidity, low temperature and low humidity, etc., the present application proposes a defrosting method, a controller and a heat pump for a heat pump to solve the above technical problems.

[0032] Please refer to Figure 2 , Figure 2 which is a schematic flowchart of an embodiment of the defrosting method of the heat pump of the present application. This method is used to defrost the evaporator outside the heat pump. In a specific embodiment, this method includes: S11: Control the refrigerant cycle of the heat pump to be in a refrigeration cycle, and make the compressor run at the starting frequency for a preset duration.

[0033] In some embodiments, when the frost layer on the evaporator is detected and the thickness of the frost layer on the outdoor evaporator reaches a certain value, this step is executed. In some other embodiments, the heat pump can also be defrosted at a set period, and this step is started to be executed. The set period can be a reasonable duration such as 1 month, 2 months, etc.

[0034] The refrigerant refrigeration cycle is as described above. Among them, in the related art, when the air conditioner defrosts, the compressor directly runs at the defrosting threshold frequency. The defrosting threshold frequency is a relatively high operating frequency. At this frequency, the refrigerant flow rate will suddenly increase. Especially in a low temperature and low humidity environment where the frost layer is thin, a large amount of high-temperature and high-pressure refrigerant releases energy slowly, making it easier for the pressure in the pipeline to exceed the threshold, which will trigger the high-pressure protection of the heat pump and cause it to shut down, resulting in insufficient defrosting. In this step, the compressor runs at the starting frequency, and the starting frequency is a relatively low frequency. Among them, the starting frequency can specifically be 0.4 times the defrosting threshold frequency, 0.45 times the defrosting threshold frequency, 0.5 times the defrosting threshold frequency, 0.6 times the defrosting threshold frequency, etc. When the compressor runs at the starting frequency, an appropriate amount of refrigerant is exhausted from the compressor and enters the outdoor heat exchanger. The temperature, pressure and flow rate of the refrigerant will not be too high. Among them, the preset duration is a fixed value, and the preset duration can specifically be a reasonable value such as 15s, 18s, 20s, 10s, etc.

[0035] In some embodiments, by switching the four-way valve, the refrigerant cycle of the heat pump is in the refrigeration cycle.

[0036] In some embodiments, when performing this step, it further includes: turning off the outdoor fan to stop blowing air on the evaporator during defrosting, so as to improve the defrosting efficiency.

[0037] In some embodiments, if the operating frequency of the compressor is greater than the starting frequency when defrosting starts, control the compressor to first reduce the frequency to the starting frequency, and then control the compressor to operate at the starting frequency for a preset duration.

[0038] S12: Obtain the outlet temperature of the evaporator and determine whether the outlet temperature reaches the target temperature.

[0039] In this embodiment, the outlet temperature of the evaporator is detected by a temperature sensor. In some other embodiments, the outlet temperature can also be obtained by other types of temperature detection devices such as an infrared sensor. In addition, the number of temperature sensors can be one or more, and the overall defrosting state of the evaporator can be reflected by the average value of multiple temperature values.

[0040] In some embodiments, preferably, the target temperature is several degrees greater than zero degrees. The target temperature can specifically be reasonable temperatures such as 8 degrees, 9 degrees, 10 degrees, etc. It is easy to understand that the frosting temperature is approximately zero degrees. Setting the target temperature to be several degrees greater than zero degrees can enable the evaporator to defrost more fully when the outlet temperature reaches the target temperature, improving the defrosting effect.

[0041] Among them, in this step, if the outlet temperature reaches the target temperature, execute S131; if the outlet temperature does not reach the target temperature, execute S132.

[0042] S131: Defrosting is completed.

[0043] In some embodiments, when it is obtained that the outlet temperature reaches the target temperature, continuously detect the outlet temperature; in response to the outlet temperature reaching the target temperature and lasting for the target duration, defrosting is completed. Among them, the target duration can specifically be reasonable values such as 15s, 12s, 18s, 20s, etc.

[0044] In some embodiments, after defrosting is completed, it further includes: controlling the outdoor fan to start to blow off the melted water droplets on the evaporator.

[0045] S132: Adjust the preset duration based on the magnitude of the outlet temperature to obtain a corrected duration.

[0046] S14: Control the compressor to increase the frequency within the corrected duration and maintain the frequency after the increase.

[0047] After the compressor operates for a period of time, since the compressor does not operate at the defrost threshold frequency, the problem of sudden increase in flow rate and pipeline pressure exceeding the threshold is reduced. In addition, after the compressor operates for a period of time, the outlet temperature of the evaporator increases. If the compressor continues to maintain the operating frequency unchanged, there will be a problem of slow defrost efficiency. Therefore, after the compressor operates for a preset duration, it is necessary to increase the operating frequency of the compressor. Among them, the preset duration is adjusted based on the outlet temperature at the same time to obtain a corrected duration.

[0048] In some embodiments, the preset duration is adjusted based on the magnitude of the outlet temperature, and specifically, the preset duration is increased when adjusting the preset duration. It is easy to understand that in this application, the compressor starts to operate at the starting frequency during the defrosting process, and the compressor gradually increases its frequency during the defrosting process. Therefore, in the initial stage, the operating frequency of the compressor is small, and the defrosting efficiency of the heat pump is relatively slow. As the defrosting process progresses, the operating frequency of the compressor increases. Therefore, through this step, when increasing the frequency, the preset duration is adjusted at the same time to increase the preset duration, so that the compressor can operate at a low operating frequency for a short time and at a higher operating frequency for a longer time, thereby making the defrosting more thorough while improving the defrosting efficiency as much as possible.

[0049] In some embodiments, the step of controlling the compressor to increase its frequency specifically includes: if the outlet temperature does not reach the target temperature, increase the operating frequency of the compressor by the rated compensation frequency. Specifically, when the outlet temperature does not reach the target temperature, increasing the operating frequency of the compressor can improve the defrosting efficiency. In this embodiment, the rated compensation frequency is a fixed value, and the rated compensation frequency is 5 Hz, that is, each time S14 is executed, the operating frequency of the compressor is increased by 5 Hz. In some other embodiments, the rated compensation frequency can also be reasonable values such as 4 Hz, 6 Hz, 7 Hz, etc. When the rated compensation frequency is 4 Hz, each time S14 is executed, the operating frequency of the compressor is increased by 4 Hz. When the rated compensation frequency is 7 Hz, each time S14 is executed, the operating frequency of the compressor is increased by 7 Hz. In some other embodiments, the rated compensation frequency can also be a dynamic value. For example, the initial value of the rated compensation frequency is 5 Hz, and the rated compensation frequency increases each time the frequency is increased. For example, when the compressor operates at the starting frequency for the preset duration and S14 is executed for the first time, the operating frequency of the compressor is increased by 5 Hz. After operating for a period of time and S14 is executed for the second time, the operating frequency of the compressor is increased by 6 Hz, and this cycle continues.

[0050] Please refer to Figure 3 , Figure 3 which Figure 2 is a schematic flowchart of an embodiment of adjusting the preset duration based on the magnitude of the outlet temperature to obtain a corrected duration. In some embodiments, the step of adjusting the preset duration based on the magnitude of the outlet temperature to obtain a corrected duration specifically includes: S321: Determine whether the outlet temperature is greater than the threshold temperature, where the threshold temperature is less than the target temperature.

[0051] The threshold temperature is a set value, which is greater than the outlet temperature of the evaporator before defrosting and less than the target temperature. In this embodiment, the set threshold temperature is 0°C and the set target temperature is 10°C. In some other embodiments, the threshold temperature can also be a reasonable temperature such as 2°C, 3°C, etc. The set target temperature can also be a reasonable temperature such as 9°C, 11°C, etc.

[0052] Wherein, if the outlet temperature is not greater than the threshold temperature, then execute S322; if the outlet temperature is greater than the threshold temperature, then execute S323.

[0053] S322: Control the correction duration to be a preset duration.

[0054] When the outlet temperature is not greater than the threshold temperature, it indicates that the temperature of the evaporator is still relatively low and the current defrosting process is relatively slow. Controlling the correction duration to be a preset duration, the advantage of the correction duration not increasing is that the compressor still runs for a short preset duration in the next frequency stage, so that the operating frequency of the compressor can be increased again at a smaller time interval, the operating time of the compressor at a small frequency can be reduced, and the operating time of the compressor at a large frequency can be increased, which can improve the defrosting efficiency.

[0055] S323: Compensate the preset duration to obtain the correction duration.

[0056] When the outlet temperature is greater than the threshold temperature, it indicates that the temperature of the evaporator is already relatively high and the current defrosting process is relatively fast. The advantage of controlling the preset duration to increase is that the compressor runs for a long preset duration in the next frequency stage, so that the frequency of the compressor continuing to increase can be reduced when the defrosting is almost completed. It can reduce the problem that the outlet temperature of the evaporator and the system high-pressure pressure will continue to rise when the defrosting is almost completed due to the hysteresis of the temperature sensor, and can reduce the situation of too high pressure of the heat pump machine. In addition, in environments such as low temperature and high humidity and low temperature and low humidity, the preset duration can be dynamically adjusted according to different changes in the outlet temperature of the evaporator to obtain the correction duration, which can be applicable to defrosting in different environments.

[0057] Further, please refer to Figure 4 , Figure 4 Yes Figure 3 is a schematic flowchart of a method for compensating the preset duration to obtain the correction duration in. In some embodiments. If the outlet temperature is greater than the threshold temperature, the step of compensating the preset duration to obtain the correction duration specifically includes: calculating the compensation duration, and increasing the preset duration by the compensation duration to obtain the correction duration. Among them, the step of calculating the compensation duration specifically includes: S231: Determine whether it is the first time to calculate the compensation duration.

[0058] When the compressor operates at the starting frequency for a preset duration and the outlet temperature is greater than the threshold temperature for the first time, the compensation duration is calculated for the first time.

[0059] If it is the first time to calculate the compensation duration, execute S311; if it is not the first time to calculate the compensation duration, execute S312.

[0060] S311: The calculation formula for the compensation duration is: t = (T m - T 3 ) * A; where, t is the compensation duration, T m is the outlet temperature, T 3 is the threshold temperature, and A is the compensation coefficient.

[0061] S312: The calculation formula for the compensation duration is: t = (T N - T N-1 ) * A; where, T N is the outlet temperature obtained this time, and T N-1 is the outlet temperature obtained last time.

[0062] As described above, the compensation duration is positively correlated with the change in the outlet temperature of the evaporator. The advantage is that: the greater the change in the outlet temperature of the evaporator, the faster the defrosting process is reflected, the defrosting rate is already relatively high, the compensation duration is made larger, so that the frequency increase rate of the compressor can be reduced, the compressor does not need to increase the frequency frequently, and the problem that the outlet temperature of the evaporator and the system high-pressure pressure will continue to rise when the defrosting is almost completed due to the hysteresis of the temperature sensor can be reduced. Among them, A is the compensation coefficient, and A is a positive integer. In this embodiment, A is 5, and in some other embodiments, A can also be reasonable values such as 4, 6, etc.

[0063] S14: Control the compressor to increase the frequency within the correction duration and maintain the operation at the increased frequency.

[0064] After executing this step, execute S12 again.

[0065] After calculating the compensation duration, the correction duration is obtained. In this step, control the compressor to increase the frequency and control the compressor to maintain the operation at the increased frequency. Among them, the sum of the duration of increasing the frequency and the duration of maintaining the operation at the increased frequency of the compressor is the same as the correction duration.

[0066] In some embodiments, the compressor is controlled to increase its frequency at a rated frequency increase acceleration; the steps of controlling the compressor to increase its frequency within a correction duration and maintain the operation at the increased frequency specifically include: the sum of the frequency increase time of the compressor and the time of operating at the frequency after the frequency increase is the correction duration. In this embodiment, the frequency increase acceleration is 1 Hz / s. For example, if the current operating frequency of the compressor is 40 Hz and the rated compensation frequency is 5 Hz, and the calculated correction duration is 45 s, then the operating frequency of the compressor is controlled to increase from 40 Hz to 45 Hz, taking 5 seconds, and the compressor is controlled to maintain the operation at 45 Hz for 40 s, and then continue to execute S12.

[0067] Among them, the air conditioner is usually set with a defrosting threshold frequency, which is the highest operating frequency of the compressor during the set defrosting process. If the operating frequency of the compressor exceeds the highest operating frequency, it will affect the comfort of indoor users. In some embodiments, the step of controlling the compressor to increase its frequency within a correction duration further includes: in response to the frequency of the compressor reaching the defrosting threshold frequency during the frequency increase, stopping the frequency increase and controlling the compressor to operate at the defrosting threshold frequency.

[0068] In some embodiments, the defrosting method further includes: in response to the defrosting duration reaching the preset duration, the defrosting is completed. Specifically, this setting can reduce the problems that the heat pump cannot defrost normally and cannot exit the defrosting mode due to abnormal switching of the four-way valve, abnormal temperature sensor, etc.

[0069] Different from the prior art, the present application provides a defrosting method for a heat pump. This defrosting method controls the compressor to start operating at a starting frequency, and the starting frequency is a relatively low operating frequency, so there will be no problem of sudden increase in refrigerant flow rate. Therefore, it can reduce the problem of triggering the high-voltage protection of the heat pump and shutting down, and make the defrosting sufficient. In addition, the present application obtains the outlet temperature of the evaporator, adjusts the preset duration according to the outlet temperature to obtain the correction duration, and can make the compressor operate at a low frequency for a short duration and at a high frequency for a long duration according to the defrosting state. The above dynamic adjustment of the operating duration of the compressor at different frequencies according to the environment can improve the defrosting efficiency and reduce the overpressure problem of the heat pump during the defrosting process.

[0070] Finally, in a specific application scenario, please refer to Table 1 for reference: Table 1

[0071] As described above, Table 1 shows the changes in various parameters of the heat pump during a specific defrosting process. Among them, in this application scenario, the starting frequency is 35 Hz, the starting preset duration is 15 s, the target temperature is 10 °C, the rated compensation frequency is 5 Hz, the threshold temperature is 0 °C, and the compensation coefficient is 5. As shown in the first column of Table 1, the heat pump operates at the starting frequency of 35 Hz for the preset duration of 15 s. After the operation, the outlet temperature of the evaporator is -3 °C. Since the outlet temperature of the evaporator is less than the threshold temperature, the controlled correction duration is the same as the preset duration, which is 15 s. In the second column, the operating frequency of the compressor increases, and the increase amplitude is the rated compensation frequency. After the frequency increase, the compressor operates at 40 Hz for 15 s. After the operation, the outlet temperature of the evaporator is -1 °C. Since the outlet temperature is less than the threshold temperature, the controlled correction duration and the preset duration remain the same, and the operating frequency of the compressor continues to increase. In the third column, the compressor operates at the increased frequency of 45 Hz for 15 s. After the operation, the outlet temperature of the evaporator is 1 °C. Since the outlet temperature is greater than the threshold temperature and it is the first time to calculate the compensation duration, the formula for calculating the compensation duration is t = (T m -T 3 ). The calculated compensation duration is 5 s, so the controlled correction duration is 20 s, and the operating frequency of the compressor increases. In the fourth column, the compressor operates at the increased frequency of 50 Hz for 20 s. After the operation, the outlet temperature of the evaporator is 3 °C. The formula for calculating the compensation duration is t = (T N -T N-1 ). The obtained compensation duration is 10 s, so the controlled correction duration is 25 s, and defrosting is performed as shown in Table 1. Among them, in the sixth column, the outlet temperature of the evaporator is 10 °C. Since the outlet temperature reaches the target temperature, the defrosting is completed, and the outdoor fan is turned on to start decreasing the operating frequency of the compressor.

[0072] For the above defrosting method, controlling the compressor to start operating at the starting frequency, where the starting frequency is a relatively low operating frequency, there will be no problem of sudden increase in refrigerant flow rate. Therefore, it can reduce the problem of triggering the high-voltage protection of the heat pump and shutting down, making the defrosting sufficient. In addition, in this application, by obtaining the outlet temperature of the evaporator and adjusting the preset duration according to the outlet temperature to obtain the correction duration, the compressor can operate at a low frequency for a short duration and at a high frequency for a long duration according to the defrosting state. The above dynamic adjustment of the operating duration of the compressor at different frequencies according to the environment can improve the defrosting efficiency and also reduce the problem of overpressure of the heat pump during defrosting.

[0073] Correspondingly, this application also proposes a heat pump, and the defrosting control of the heat pump is carried out by the defrosting control method described in the above embodiments.

[0074] Among them, the heat pump machine includes a compressor, a condenser, an evaporator, a four-way valve and a throttle valve; the compressor includes an exhaust port and a suction port; the four-way valve includes a first flow channel and a second flow channel; the four-way valve is configured to be able to switch the connection state, so that in the heating mode, the exhaust port of the compressor, the first flow channel (condenser flow channel) of the four-way valve, the condenser, the throttle valve, the evaporator, the second flow channel (evaporator flow channel) of the four-way valve, and the suction port of the compressor are sequentially connected to form a heating circuit; in the cooling mode, the exhaust port of the compressor, the second flow channel of the four-way valve, the evaporator, the throttle valve, the condenser, the first flow channel of the four-way valve, and the suction port of the compressor are sequentially connected to form a cooling circuit.

[0075] Please refer to Figure 5 , Figure 5 which is a structural block diagram of an embodiment of the controller of the present application. Correspondingly, the present application also proposes a controller 100, and the controller 100 controls the defrosting of the heat pump machine through the above defrosting method. The controller 100 includes a control module 200, an acquisition module 300 and a judgment module 400. The control module 200 is used to control the refrigerant circulation of the heat pump machine to be in the refrigeration cycle, so that the compressor operates at the starting frequency for a preset duration; the acquisition module 300 is used to acquire the outlet temperature of the evaporator; the judgment module 400 is used to judge whether the outlet temperature reaches the target temperature; if the outlet temperature reaches the target temperature, the control module 200 controls the defrosting to be completed; if the outlet temperature does not reach the target temperature, the control module 200 adjusts the preset duration based on the magnitude of the outlet temperature to obtain a corrected duration, and controls the compressor to increase the frequency within the corrected duration and maintain the frequency after the increase, and executes the steps of acquiring the outlet temperature of the evaporator and judging whether the outlet and temperature reach the target temperature.

[0076] In some embodiments, the step of the control module 200 controlling the compressor to increase the frequency specifically includes: if the outlet temperature does not reach the target temperature, increasing the operating frequency of the compressor by the rated compensation frequency.

[0077] In some embodiments, the step of the control module 200 adjusting the preset duration based on the magnitude of the outlet temperature to obtain a corrected duration specifically includes: judging whether the outlet temperature is greater than the threshold temperature, where the threshold temperature is less than the target temperature; if the outlet temperature is not greater than the threshold temperature, controlling the corrected duration to be the preset duration; if the outlet temperature is greater than the threshold temperature, compensating the preset duration to obtain a corrected duration.

[0078] In some embodiments, if the outlet temperature is greater than the threshold temperature, the step of the control module 200 compensating the preset duration to obtain a corrected duration specifically includes: calculating the compensation duration, increasing the preset duration by the compensation duration to obtain a corrected duration; among them, the step of calculating the compensation duration specifically includes: judging whether it is the first time to calculate the compensation duration; if it is the first time to calculate the compensation duration, the calculation formula of the compensation duration is: t = (T m-T 3 ) * A; wherein, t is the compensation duration, T m is the outlet temperature, T 3 is the threshold temperature, and A is the compensation coefficient; if it is not the first calculation of the compensation duration, the formula for calculating the compensation duration is: t = (T N -T N-1 ) * A; wherein, T N is the outlet temperature obtained this time, and T N-1 is the outlet temperature obtained last time.

[0079] In some embodiments, the control module 200 controls the compressor to increase the frequency at a rated frequency increase acceleration; the steps of controlling the compressor to increase the frequency within the correction duration and maintain the frequency after the frequency increase include: the sum of the frequency increase time of the compressor and the time of running at the frequency after the frequency increase is the correction duration.

[0080] In some embodiments, the steps of the control module 200 controlling the compressor to increase the frequency within the correction duration and maintain the frequency after the frequency increase specifically include: in response to the frequency of the compressor reaching the defrost threshold frequency during the frequency increase, stop increasing the frequency and control the compressor to run at the defrost threshold frequency.

[0081] In some embodiments, the steps of the control module 200 controlling the defrosting to complete when the outlet temperature reaches the target temperature specifically include: if the outlet temperature reaches the target temperature, continuously detect the outlet temperature; in response to the outlet temperature reaching the target temperature and lasting for the target duration, the defrosting is completed.

[0082] In some embodiments, when the defrosting duration reaches the preset duration, the control module 200 controls the defrosting to complete.

[0083] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structure or equivalent principle transformation made by using the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be included in the patent protection scope of the present invention by the same token.

Claims

1. A defrosting method for a heat pump, characterized in that: The defrosting method comprises: Control the refrigerant cycle of the heat pump machine to be in the refrigeration cycle, so that the compressor runs at the starting frequency for a preset time; Obtaining the outlet temperature of the evaporator, and determining whether the outlet temperature reaches the target temperature; if the outlet temperature reaches the target temperature, defrosting is completed; If the outlet temperature does not reach the target temperature, adjusting the preset duration based on the outlet temperature to obtain a corrected duration; The compressor is controlled to increase the frequency within the correction time and maintain the frequency after the increase, and the steps of obtaining the outlet temperature of the evaporator and judging whether the outlet temperature reaches the target temperature are executed.

2. The defrosting method according to claim 1, characterized in that: The steps of controlling the compressor frequency increase specifically include: If the outlet temperature does not reach the target temperature, the operating frequency of the compressor is increased by a rated compensation frequency.

3. The defrosting method according to claim 1, characterized in that: The step of adjusting the preset duration based on the outlet temperature to obtain a corrected duration specifically includes: Determining whether the outlet temperature is greater than a threshold temperature, wherein the threshold temperature is less than the target temperature; If the outlet temperature is not greater than the threshold temperature, the correction time is controlled to be the preset time; if the outlet temperature is greater than the threshold temperature, the preset time is compensated to obtain the correction time.

4. The defrosting method according to claim 3, characterized in that: If the outlet temperature is greater than the threshold temperature, the step of compensating the preset time length to obtain a corrected time length specifically includes: Calculating the compensation duration, and increasing the preset duration by the compensation duration to obtain the corrected duration; The step of calculating the compensation duration specifically includes: Determining whether it is the first time to calculate the compensation duration; If the compensation duration is calculated for the first time, the calculation formula for the compensation duration is: t=(T m -T3)*A; Wherein, t is the compensation duration, T m is the outlet temperature, T3 is the threshold temperature, and A is the compensation coefficient; If it is not the first time to calculate the compensation duration, the calculation formula of the compensation duration is: t=(T N -T N-1 )*A; Among them, T N is the outlet temperature obtained this time, T N-1 is the outlet temperature obtained last time.

5. The defrosting method according to claim 1, characterized in that: Controlling the compressor to increase the frequency at the rated frequency increase acceleration; The step of controlling the compressor to increase the frequency within the correction time and maintaining the increased frequency operation specifically includes: The sum of the frequency-up time of the compressor and the time during which the compressor operates at the frequency after the frequency-up is completed is the corrected duration.

6. The defrosting method according to claim 1, characterized in that: The step of controlling the compressor to increase the frequency within the correction time and maintaining the increased frequency operation specifically includes: In response to the frequency of the compressor reaching the defrost threshold frequency during frequency increase, the frequency increase is stopped, Control the compressor to run at the defrost threshold frequency.

7. The defrosting method according to claim 1, characterized in that: The step of completing defrosting if the outlet temperature reaches the target temperature specifically includes: If the outlet temperature reaches the target temperature, continuously detecting the outlet temperature; In response to the outlet temperature reaching the target temperature and lasting for a target time period, defrosting is completed.

8. The defrosting method according to claim 1, characterized in that: The defrosting method further comprises: In response to the defrost time reaching the preset time, the defrost is completed.

9. A controller, characterized in that: The controller controls the defrosting of the heat pump machine by the defrosting method according to any one of claims 1 to 8, and the controller comprises: A control module, the control module is used to control the refrigerant cycle of the heat pump machine to be in a refrigeration cycle, so that the compressor runs at a starting frequency for a preset time; An acquisition module, the acquisition module is used to acquire the outlet temperature of the evaporator; A judgment module, the judgment module is used to judge whether the outlet temperature reaches the target temperature; if the outlet temperature reaches the target temperature, the control module controls the defrosting to be completed; if the outlet temperature does not reach the target temperature, the control module adjusts the preset time length based on the size of the outlet temperature to obtain a corrected time length, and controls the compressor to increase the frequency within the corrected time length and maintain the frequency after the increase, and executes the steps of obtaining the outlet temperature of the evaporator and judging whether the outlet temperature reaches the target temperature.

10. A heat pump, characterized in that: The heat pump machine is defrosted by controlling the defrosting method according to any one of claims 1 to 8.

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