Air conditioner and defrosting control method and device thereof, storage medium and program product

Abstract

The invention provides an air conditioner and a defrosting control method and device thereof, a storage medium and a program product, and the method comprises the following steps: under a heating operation condition, when a defrosting condition is met, entering a first defrosting stage; in the first defrosting stage, the compressor is controlled to operate in a frequency reduction mode, and when a first preset condition is met, frequency reduction is stopped, and a second defrosting stage is started; in the second defrosting stage, the four-way valve is controlled to reverse, the compressor is controlled to operate in a frequency rising mode, when it is detected that the suction pressure value is within the preset pressure value interval and kept for second preset time, frequency rising is stopped, and when a second preset condition is met, a third defrosting stage is started; and in the third defrosting stage, the compressor is controlled to run in an underclocking mode, and when it is detected that the exhaust pressure value is reduced to the safe reversing value and is kept for third preset time, or when the time for entering the third defrosting stage reaches the preset maximum allowable time of the third stage, underclocking, reversing of the four-way valve and defrosting quitting are stopped. According to the scheme, the reverse defrosting time of the heat pump can be shortened.

Description

Technical Field

[0001] This invention relates to the field of control, and more particularly to an air conditioner and its defrosting control method, apparatus, storage medium and program product. Background Technology

[0002] When the ambient temperature is low, after a certain period of heating operation, it is inevitable that frost will form on the evaporator surface of the air conditioner. The frost layer will affect the heat exchange of the evaporator and the overall heating effect of the unit. Therefore, it is necessary to defrost after a period of heating operation. In related technologies, air conditioner defrosting methods can be divided into hot gas bypass defrosting, heat pump reverse defrosting, and electric heating defrosting. Hot gas bypass defrosting involves using a solenoid valve to directly bypass the high-temperature, high-pressure gas discharged from the compressor in the refrigeration cycle, bypassing the condenser and directly introducing it into the evaporator, using its sensible heat for defrosting. This method can provide heating to the room while defrosting, and the defrosting switch is relatively fast. However, this method makes it difficult to ensure the uniformity of the bypass gas during defrosting, and the limited bypass gas cannot guarantee complete defrosting; the bypassed refrigerant does not pass through the expansion valve for throttling, resulting in lower defrosting efficiency and higher energy consumption, and there is a risk of excessive system pressure or refrigerant liquid slugging.

[0003] Reverse defrosting in a heat pump involves switching between cooling and heating modes, causing the high-temperature, high-pressure refrigerant to flow in the reverse direction, thus defrosting. This defrosting method offers good defrosting performance and high efficiency. However, it generally requires pausing the compressor before restarting it for defrosting, and switching back from defrosting mode to normal heating mode also requires pausing the compressor before restarting it. This results in a longer defrosting response time, extending the overall defrosting process and causing greater fluctuations in indoor temperature, impacting the user experience. Summary of the Invention

[0004] The main objective of this invention is to overcome the deficiencies of the aforementioned related technologies and provide an air conditioner and its defrosting control method, device, storage medium, and program product to solve the problem that the long reverse defrosting response time of heat pumps affects the user experience in the related technologies.

[0005] This invention provides a defrosting control method for an air conditioner, comprising: when the air conditioner is in heating operation, determining whether the air conditioner meets the conditions for entering defrost; when the conditions for entering defrost are met, entering a first defrost stage; in the first defrost stage, controlling the compressor to reduce its frequency at a preset frequency reduction rate; when a first preset condition is met, controlling the compressor to stop reducing its frequency, and then exiting the first defrost stage and entering a second defrost stage; in the second defrost stage, controlling the four-way valve to switch, controlling the compressor to increase its frequency at a preset frequency increase rate; when the suction pressure value is detected to be within a preset pressure value range and maintained for a second preset time, controlling the compressor to stop increasing its frequency; when the second preset condition is met, exiting the second defrost stage and entering a third defrost stage; in the third defrost stage, controlling the compressor to reduce its frequency at a preset frequency reduction rate; when the discharge pressure value is detected to drop to a safe switching value and maintained for a third preset time, or when the time in the third defrost stage reaches a preset maximum allowable time for the third stage, controlling the compressor to stop reducing its frequency, and then controlling the four-way valve to switch, exiting the third defrost stage and continuing heating operation.

[0006] Optionally, it further includes: in the first defrosting stage, controlling the speed of the internal fan, the speed of the external fan, and the opening of the throttling device to adjust according to the preset values ​​of the first defrosting stage, wherein: controlling the internal fan to operate at the preset first gear, controlling the external fan to operate at the preset second gear, and controlling the opening of the throttling device to decrease to the first preset opening.

[0007] Optionally, it also includes: in the second defrosting stage, after the four-way valve is reversed, the opening of the throttling device is increased to a preset maximum opening, and the internal fan and external fan are shut down.

[0008] Optionally, it also includes: in the third defrosting stage, after controlling the four-way valve to switch, controlling the speed of the internal fan, the speed of the external fan, and the opening of the throttling device to adjust according to the preset values ​​of the third defrosting stage, and maintaining this for a fourth preset time, and then exiting the third defrosting stage, wherein: the internal fan is controlled to be turned off, the external fan is controlled to operate at the preset first gear of the external fan, and the opening of the throttling device is controlled to be reduced to the second preset opening.

[0009] Optionally, the first preset condition includes at least one of the following conditions: the exhaust pressure value is reduced to a preset safe reversing value and maintained for a first preset time, the time to enter the first defrosting stage reaches the preset maximum allowable time for the first stage, and the compressor frequency is reduced to a preset minimum frequency value.

[0010] Optionally, the second preset condition includes whether the outdoor ambient temperature, the outdoor heat exchanger temperature, and the defrosting time meet the preset conditions.

[0011] In another aspect, the present invention provides a defrosting control device for an air conditioner, comprising: a judgment unit, configured to determine whether the air conditioner meets the conditions for entering defrosting when the air conditioner is in heating operation, and to enter a first defrosting stage when the conditions for entering defrosting are met; a first control unit, configured to control the compressor to operate at a preset frequency reduction rate during the first defrosting stage, and to control the compressor to stop frequency reduction when a first preset condition is met, and then exit the first defrosting stage and enter a second defrosting stage; and a second control unit, configured to control the four-way valve to reverse during the second defrosting stage, and to control the compressor to operate at a preset frequency increase rate. Okay, when the suction pressure value is detected to be within the preset pressure range and maintained for a second preset time, the compressor is controlled to stop increasing frequency. When the second preset condition is met, the second defrosting stage is exited and the third defrosting stage is entered. The third control unit is used to control the compressor to reduce frequency at a preset frequency reduction rate in the third defrosting stage. When the discharge pressure value is detected to drop to the safe reversing value and maintained for a third preset time, or when the time in the third defrosting stage reaches the preset maximum allowable time of the third stage, the compressor is controlled to stop reducing frequency. Then, the four-way valve is controlled to reverse, exit the third defrosting stage, and continue heating operation.

[0012] Optionally, the first control unit is further configured to: in the first defrosting stage, control the speed of the internal fan, the speed of the external fan, and the opening of the throttling device to adjust according to the preset values ​​of the first defrosting stage, wherein: the internal fan is controlled to operate at the preset first gear, the external fan is controlled to operate at the preset second gear, and the opening of the throttling device is controlled to decrease to the first preset opening.

[0013] Optionally, the second control unit is further configured to: after controlling the four-way valve to switch direction in the second defrosting stage, control the opening of the throttling device to increase to a preset maximum opening, and control the internal fan and the external fan to shut down.

[0014] Optionally, the third control unit is further configured to: after controlling the four-way valve to switch direction in the third defrosting stage, control the speed of the internal fan, the speed of the external fan, and the opening of the throttling device to adjust according to the preset values ​​of the third defrosting stage, and maintain this for a fourth preset time before exiting the third defrosting stage, wherein: the internal fan is controlled to be turned off, the external fan is controlled to operate at the preset first gear, and the opening of the throttling device is controlled to be reduced to the second preset opening.

[0015] Optionally, the first preset condition includes at least one of the following conditions: the exhaust pressure value is reduced to a preset safe reversing value and maintained for a first preset time, the time to enter the first defrosting stage reaches the preset maximum allowable time for the first stage, and the compressor frequency is reduced to a preset minimum frequency value.

[0016] Optionally, the second preset condition includes whether the outdoor ambient temperature, the outdoor heat exchanger temperature, and the defrosting time meet the preset conditions.

[0017] In another aspect, the present invention provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any of the methods described above.

[0018] In another aspect, the present invention provides an air conditioner, including a processor, a memory, and a computer program stored in the memory that can run on the processor, wherein the processor executes the program to implement the steps of any of the methods described above.

[0019] In another aspect, the present invention provides an air conditioner including any of the defrosting control devices described above.

[0020] In another aspect, the present invention provides a computer program product, including a computer program that, when executed by a processor, implements the steps of any of the methods described above.

[0021] According to the technical solution of the present invention, the method of first reducing the frequency and then switching the four-way valve to achieve rapid entry and exit of the defrost mode is adopted, which shortens the time of reverse defrosting of the heat pump and ensures a better defrosting effect of the air conditioner. At the same time, it is also beneficial to reduce the fluctuation range of system pressure and flow and extend the working life of the compressor.

[0022] According to the technical solution of the present invention, using the exhaust pressure or intake pressure as the compressor frequency control condition during defrosting can better control the system's intake and exhaust pressures, which is beneficial to solving the problem of system pressure differences caused by different ambient temperatures, and has stronger commutation universality. Attached Figure Description

[0023] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of an embodiment of the defrosting control method for an air conditioner provided by the present invention; Figure 2 This is a schematic diagram of a specific embodiment of the defrosting control method for air conditioners provided by the present invention; Figure 3 This is a structural block diagram of an embodiment of the defrosting control device for an air conditioner provided by the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0025] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0026] This invention provides a defrosting control method for air conditioners. This method is mainly used in air conditioning systems employing reverse defrosting via a heat pump.

[0027] Figure 1 This is a schematic diagram of an embodiment of the defrosting control method for air conditioners provided by the present invention.

[0028] like Figure 1 As shown, according to an embodiment of the present invention, the defrosting control method includes at least steps S110, S120, S130 and S140.

[0029] Step S110: When the air conditioner is in heating mode, determine whether the air conditioner meets the conditions for entering defrost. If the conditions for entering defrost are met, enter the first stage of defrost.

[0030] In one specific implementation, the frost thickness is determined, and when the frost layer is determined to be thick, the first stage of defrosting is initiated. Specifically, when the outdoor ambient temperature is detected to meet the conditions for initiating defrosting, the time since the last defrosting is calculated, and it is determined whether the time since the last defrosting meets the conditions for initiating defrosting. When both the outdoor ambient temperature and the time since the last defrosting meet the conditions for initiating defrosting, it is considered that the frost layer has reached the thickness required for defrosting, and the first stage of defrosting is initiated.

[0031] Step S120: In the first defrosting stage, the compressor is controlled to operate at a preset frequency reduction speed. When the first preset condition is met, the compressor is controlled to stop reducing the frequency, and then the first defrosting stage is exited, and the second defrosting stage begins.

[0032] Specifically, the first preset condition includes at least one of the following: the exhaust pressure value decreases to a preset safe reversing value and remains at that value for a first preset time t1; the time for entering the first defrost stage reaches a preset maximum allowable time for the first stage; and the compressor frequency decreases to a preset minimum frequency value. When the defrost entry condition is met, the first defrost stage is entered. In the first defrost stage, the four-way valve remains open, the exhaust pressure value Pout is detected, and a timer starts. Subsequently, the compressor is controlled to operate at a preset frequency reduction rate. When the exhaust pressure value is detected to decrease to the preset safe reversing value Pout_max and remain at that value for a first preset time t1, or when the time for entering the first defrost stage reaches the preset maximum allowable time for the first stage t1_max, or when the compressor frequency ft_current decreases to a preset minimum frequency value ft_min, the compressor is controlled to stop reducing its frequency. At this point, the first defrost stage is exited, and the second defrost stage begins.

[0033] Preferably, in the first stage of defrosting, the speed of the internal fan, the speed of the external fan, and the opening of the throttling device can be adjusted according to preset values ​​for the first stage of defrosting. In one specific embodiment, the internal fan is controlled to operate at a preset first gear (e.g., the maximum gear), the external fan is controlled to operate at a preset second gear (e.g., the medium gear), and the opening of the throttling device (e.g., an electronic expansion valve) is reduced to a first preset opening (e.g., 1 / 4 of the total opening).

[0034] Performing the above operations can reduce the pressure in the system, allowing the four-way valve to switch without stopping the compressor. Although this process also takes some time, it is much faster than starting and stopping the compressor, which helps to speed up the defrosting process and improve the user's actual experience.

[0035] Step S130: In the second defrosting stage, the four-way valve is controlled to switch, and the compressor is controlled to increase its frequency at a preset frequency increase rate. When the suction pressure value is detected to be within the preset pressure value range and maintained for a second preset time, the compressor is controlled to stop increasing its frequency. When the second preset condition is met, the second defrosting stage is exited, and the third defrosting stage is entered.

[0036] Specifically, in the second stage of defrosting, the four-way valve is switched off, i.e., closed. At this time, the refrigerant in the outdoor heat exchanger flows in the opposite direction (relative to the heating operation). The high-temperature, high-pressure refrigerant flows to the frosted outdoor heat exchanger to defrost. To accelerate the defrosting speed, the compressor is controlled to rapidly increase its frequency at a preset rate (e.g., 1 level / 1 second), and the suction pressure is monitored in real time. When the suction pressure value is detected to be within the range [P_low, P_high] and maintained for a second preset time t2 (e.g., 1 second), the frequency increase is stopped. After the four-way valve is switched off, while the compressor is controlled to increase its frequency at the preset rate, the opening of the throttling device (e.g., an electronic expansion valve) is increased to the preset maximum opening. The purpose of these control logics is to bring more heat to the outdoor heat exchanger and accelerate defrosting, but at the same time, a large amount of cooling capacity is also brought to the indoor heat exchanger, causing the indoor heat exchanger temperature to drop to an extremely low level. Therefore, in order to prevent the air conditioner from blowing out cold air, the indoor and outdoor fans are turned off at this time. Turning off the indoor fan can avoid large fluctuations in indoor temperature during defrosting. At the same time, turning off the outdoor fan can prevent cold outdoor air from blowing over the outdoor heat exchanger. This can both increase the temperature of the outdoor heat exchanger, speed up defrosting, and reduce heat loss, thus reducing energy consumption (when the system switches to heating mode, the heat left on the outdoor heat exchanger will be "transferred" back to the indoor heat exchanger).

[0037] At this time, the entire unit is undergoing defrosting. When the second preset condition is met, the second defrosting stage is exited, and the third defrosting stage begins. Specifically, the outdoor ambient temperature, the outdoor heat exchanger temperature, and the defrosting time are detected. It is determined whether the outdoor ambient temperature, the outdoor heat exchanger temperature, and the defrosting time meet the second preset condition. If they do, the second defrosting stage is exited, and the third defrosting stage begins.

[0038] The second preset condition may specifically include: the outdoor ambient temperature and the outdoor heat exchanger temperature satisfying that the outdoor ambient temperature is greater than a first preset temperature value and the outdoor heat exchanger temperature is greater than a second preset temperature value, and this condition persists for a first duration; or the outdoor ambient temperature is less than a first preset temperature value and the outdoor heat exchanger temperature is greater than a third preset temperature value, and this condition persists for a second duration, and the defrosting time reaches the preset maximum defrosting operation time. The defrosting time is the time from the start of the second stage of defrosting, controlling the four-way valve to switch direction, until entering the third stage of defrosting.

[0039] That is, when the outdoor ambient temperature and the outdoor heat exchanger temperature meet the following conditions: the outdoor ambient temperature is greater than the first preset temperature value and the outdoor heat exchanger temperature is greater than the second preset temperature value, and this condition is maintained for a first duration; or the outdoor ambient temperature is less than the first preset temperature value and the outdoor heat exchanger temperature is greater than the third preset temperature value, and this condition is maintained for a second duration, and the defrosting time reaches the preset maximum defrosting operation time tmax, the second defrosting stage is exited and the third defrosting stage is entered.

[0040] For example, if the outdoor ambient temperature is >0℃ and the average pipe temperature of the outdoor heat exchanger is >15℃ for 3 seconds, or if the outdoor ambient temperature is <0℃ and the average pipe temperature of the outdoor heat exchanger is >9℃ for 10 seconds, the defrosting time reaches the preset maximum defrosting operation time tmax (for example, tmax = 180s can be taken).

[0041] During defrosting, especially during the brief period before and after the four-way valve switches, the compressor's suction and discharge pressures may exceed the compressor's allowable operating range. This invention uses pressure as the frequency control condition, which can better control the system's suction and discharge pressures, ensuring that the suction and discharge pressures operate within the compressor's allowable operating range. This helps to solve the problem of system pressure differences caused by different ambient temperatures, and the switching is more universal.

[0042] In step S140, during the third defrosting stage, the compressor is controlled to reduce its frequency at a preset frequency reduction rate. When the discharge pressure value is detected to drop to a safe reversing value and remain at that value for a third preset time, or when the time spent in the third defrosting stage reaches the preset maximum allowable time for the third stage, the compressor is controlled to stop reducing its frequency, and then the four-way valve is controlled to reverse, exiting the third defrosting stage.

[0043] Specifically, in the third stage of defrosting, the discharge pressure value Pout is obtained, the compressor starts to reduce the frequency, and stops reducing the frequency after detecting that the discharge pressure value has dropped to the safe reversing value Pout_max and maintaining it for the third preset time t3, or stops reducing the frequency after reaching the maximum allowable time t3_max for this stage. Then the four-way valve reverses again and remains in the open state, exiting the third stage of defrosting, that is, exiting defrosting and continuing heating operation.

[0044] Preferably, after controlling the reversal of the four-way valve, the speed of the internal fan, the speed of the external fan, and the opening of the throttling device are adjusted according to the preset values ​​of the third stage of defrosting. After maintaining this for a fourth preset time, the third stage of defrosting is exited, that is, the whole unit performs specific low-frequency heating operation, and after maintaining this for a fourth preset time t4, the third stage of defrosting is exited, and the normal heating stage is entered. In one specific embodiment, adjusting the speed of the internal fan, the speed of the external fan, and the opening of the throttling device according to the preset values ​​of the third stage of defrosting includes: controlling the internal fan to shut down, controlling the external fan to operate at a preset first speed (the preset first speed is greater than the preset second speed, for example, the preset first speed is the maximum speed of the external fan), and controlling the opening of the throttling device (for example, an electronic expansion valve) to decrease to a second preset opening (for example, 1 / 3 of the total opening).

[0045] To clearly illustrate the technical solution of the present invention, the execution flow of the defrosting control method for air conditioners provided by the present invention will be described below with reference to a specific embodiment.

[0046] Figure 2 This is a schematic diagram of a specific embodiment of the defrosting control method for air conditioners provided by the present invention. Figure 2 As shown, during the air conditioning heating stage, the frost thickness is determined based on acquired parameters. When the frost thickness is deemed too thick, defrosting begins. First, in the first defrosting stage, the four-way valve remains open, the exhaust pressure value Pout is acquired, the compressor begins to reduce its frequency, and the indoor and outdoor fans and electronic expansion valve adjust according to preset values. Frequency reduction stops when the exhaust pressure drops to the safe reversing value Pout_max and remains for a time t1, or when the maximum allowable time t1_max for this stage is reached, or when the current compressor frequency value ft_current reaches the minimum frequency value ft_min. Then, the first defrosting stage ends. In the second defrosting stage, the four-way valve remains closed, and the compressor rapidly increases its frequency at a rate of 1 level / 1 second. Frequency increase stops when the suction pressure value is within the range [P_low, P_high] and remains for a time t2. At this time, the indoor and outdoor fans are turned off, and the electronic expansion valve is adjusted to the maximum opening. The whole unit is defrosting. It is judged whether the outdoor ambient temperature, outdoor heat exchanger temperature (outdoor heat exchanger pipe temperature) and defrosting time meet the preset conditions. If they are met, the second stage of defrosting is exited and the third stage of defrosting is entered. In the third stage of defrosting, the exhaust pressure value Pout is obtained, the compressor starts to reduce the frequency, and stops reducing the frequency after detecting that the exhaust pressure value drops to the safe reversing value Pout_max and is maintained for time t3, or stops reducing the frequency after reaching the maximum allowable time t3_max of this stage. Then the four-way valve is reversed again and kept open. The indoor and outdoor fans and the electronic expansion valve are adjusted according to the preset values, that is, the whole unit performs specific low-frequency heating operation, and exits the third stage of defrosting after time t4, and enters the normal heating stage.

[0047] The present invention also provides a defrosting control device for an air conditioner. This device is mainly used in air conditioning systems that employ reverse defrosting via a heat pump.

[0048] Figure 3 This is a structural block diagram of an embodiment of the defrosting control device for an air conditioner provided by the present invention. Figure 3 As shown, the defrosting control device 100 includes: a judgment unit 110, a first control unit 120, a second control unit 130, and a third control unit 140.

[0049] The judgment unit 110 is used to determine whether the air conditioner meets the conditions for entering defrost when the air conditioner is in heating mode, and when the conditions for entering defrost are met, it enters the first stage of defrosting.

[0050] In one specific implementation, the frost thickness is determined, and when the frost layer is determined to be thick, the first stage of defrosting is initiated. Specifically, when the outdoor ambient temperature is detected to meet the conditions for initiating defrosting, the time since the last defrosting is calculated, and it is determined whether the time since the last defrosting meets the conditions for initiating defrosting. When both the outdoor ambient temperature and the time since the last defrosting meet the conditions for initiating defrosting, it is considered that the frost layer has reached the thickness required for defrosting, and the first stage of defrosting is initiated.

[0051] The first control unit 120 is used to control the compressor to reduce its frequency at a preset rate during the first defrosting stage. When a first preset condition is met, the compressor is controlled to stop reducing its frequency, and then the first defrosting stage is exited, and the second defrosting stage is entered.

[0052] Specifically, the first preset condition includes at least one of the following: the exhaust pressure value decreases to a preset safe reversing value and remains at that value for a first preset time; the time spent in the first defrosting stage reaches a preset maximum allowable time for the first stage; and the compressor frequency decreases to a preset minimum frequency value. When the defrosting conditions are met, the first defrosting stage begins. In the first defrosting stage, the four-way valve remains open, the exhaust pressure value Pout is detected, and a timer begins. Subsequently, the compressor is controlled to operate at a preset frequency reduction rate. When the exhaust pressure value decreases to the preset safe reversing value Pout_max and remains at that value for a first preset time t1, or when the time spent in the first defrosting stage reaches the preset maximum allowable time for the first stage t1_max, or when the compressor frequency ft_current decreases to a preset minimum frequency value ft_min, the compressor is controlled to stop reducing its frequency. At this point, the first defrosting stage ends, and the second defrosting stage begins.

[0053] Preferably, the first control unit 120 can also be used to: in the first defrosting stage, control the speed of the internal fan, the speed of the external fan, and the opening of the throttling device to adjust according to the preset values ​​of the first defrosting stage.

[0054] In one specific implementation, the internal fan is controlled to operate at a preset first gear (e.g., the maximum gear of the internal fan), the external fan is controlled to operate at a preset second gear (e.g., the medium gear), and the opening of the throttling device (e.g., the electronic expansion valve) is reduced to a first preset opening (e.g., 1 / 4 of the total opening).

[0055] Performing the above operations can reduce the pressure in the system, allowing the four-way valve to switch without stopping the compressor. Although this process also takes some time, it is much faster than starting and stopping the compressor, which helps to speed up the defrosting process and improve the user's actual experience.

[0056] The second control unit 130 is used to control the four-way valve to switch direction in the second defrosting stage, control the compressor to increase frequency at a preset frequency increase rate, control the compressor to stop increasing frequency when the suction pressure value is detected to be in the preset pressure value range and maintained for a second preset time, and exit the second defrosting stage when the second preset condition is met, and enter the third defrosting stage.

[0057] Specifically, in the second defrosting stage, the second control unit 130 controls the four-way valve to switch to the closed state. At this time, the refrigerant in the outdoor heat exchanger will flow in the reverse direction (relative to the heating operation). The high-temperature and high-pressure refrigerant flows to the frosted outdoor heat exchanger to defrost. To speed up the defrosting process, the compressor is controlled to rapidly increase its frequency at a preset rate (e.g., 1 level / 1 second). The suction pressure is monitored in real time. When the suction pressure value is detected to be within the range [P_low, P_high] and maintained for a second preset time t2 (e.g., 1 second), the frequency increase is stopped. After controlling the four-way valve to switch, while controlling the compressor to increase its frequency at the preset rate, the opening of the throttling device (e.g., an electronic expansion valve) is increased to the preset maximum opening. The purpose of these control logics is to bring more heat to the outdoor heat exchanger and accelerate defrosting, but at the same time, a large amount of cooling capacity is also brought to the indoor heat exchanger, causing the indoor heat exchanger temperature to drop to an extremely low level. Therefore, in order to prevent the air conditioner from blowing out cold air, the indoor and outdoor fans are turned off at this time. Turning off the indoor fan can avoid large fluctuations in indoor temperature during defrosting. At the same time, turning off the outdoor fan can prevent cold outdoor air from blowing over the outdoor heat exchanger. This can both increase the temperature of the outdoor heat exchanger, speed up defrosting, and reduce heat loss, thus reducing energy consumption (when the system switches to heating mode, the heat left on the outdoor heat exchanger will be "transferred" back to the indoor heat exchanger).

[0058] At this time, the entire unit is undergoing defrosting. When the second preset condition is met, the second defrosting stage is exited, and the third defrosting stage begins. Specifically, the outdoor ambient temperature, the outdoor heat exchanger temperature, and the defrosting time are detected. It is determined whether the outdoor ambient temperature, the outdoor heat exchanger temperature, and the defrosting time meet the preset conditions. If they do, the second defrosting stage is exited, and the third defrosting stage begins.

[0059] The second preset condition may specifically include: the outdoor ambient temperature and the outdoor heat exchanger temperature satisfying that the outdoor ambient temperature is greater than a first preset temperature value and the outdoor heat exchanger temperature is greater than a second preset temperature value, and this condition persists for a first duration; or the outdoor ambient temperature is less than a first preset temperature value and the outdoor heat exchanger temperature is greater than a third preset temperature value, and this condition persists for a second duration, and the defrosting time reaches the preset maximum defrosting operation time. The defrosting time is the time from the start of the second stage of defrosting, controlling the four-way valve to switch direction, until entering the third stage of defrosting.

[0060] That is, when the outdoor ambient temperature and the outdoor heat exchanger temperature meet the following conditions: the outdoor ambient temperature is greater than the first preset temperature value and the outdoor heat exchanger temperature is greater than the second preset temperature value, and this condition is maintained for a first duration; or the outdoor ambient temperature is less than the first preset temperature value and the outdoor heat exchanger temperature is greater than the third preset temperature value, and this condition is maintained for a second duration, and the defrosting time reaches the preset maximum defrosting operation time tmax, the second defrosting stage is exited and the third defrosting stage is entered.

[0061] For example, if the outdoor ambient temperature is >0℃ and the average pipe temperature of the outdoor heat exchanger is >15℃ for 3 seconds, or if the outdoor ambient temperature is <0℃ and the average pipe temperature of the outdoor heat exchanger is >9℃ for 10 seconds, the defrosting time reaches the preset maximum defrosting operation time tmax (for example, tmax = 180s can be taken).

[0062] During defrosting, especially during the brief period before and after the four-way valve switches, the compressor's suction and discharge pressures may exceed the compressor's allowable operating range. This invention uses pressure as the frequency control condition, which can better control the system's suction and discharge pressures, ensuring that the suction and discharge pressures operate within the compressor's allowable operating range. This helps to solve the problem of system pressure differences caused by different ambient temperatures, and the switching is more universal.

[0063] The third control unit 140 is used to control the compressor to reduce its frequency at a preset frequency reduction rate during the third defrosting stage. When the discharge pressure value is detected to drop to a safe reversing value and remain at that value for a third preset time, or when the time spent in the third defrosting stage reaches the preset maximum allowable time for the third stage, the control unit 140 controls the compressor to stop reducing its frequency and then controls the four-way valve to reverse, exiting the third defrosting stage and continuing heating operation.

[0064] Specifically, in the third stage of defrosting, the discharge pressure value Pout is obtained, the compressor starts to reduce the frequency, and stops reducing the frequency after detecting that the discharge pressure value has dropped to the safe reversing value Pout_max and maintaining it for the third preset time t3, or stops reducing the frequency after reaching the maximum allowable time t3_max for this stage. Then the four-way valve reverses again and remains in the open state, exiting the third stage of defrosting, that is, exiting defrosting and continuing heating operation.

[0065] Preferably, the third control unit 140 is further configured to: in the third defrosting stage, after controlling the four-way valve to switch, control the internal fan speed, external fan speed, and throttling device opening to adjust according to the preset values ​​of the third defrosting stage, maintain this for a fourth preset time, and then exit the third defrosting stage, i.e., the whole unit performs specific low-frequency heating operation, and maintains this for a fourth preset time t4 before exiting the third defrosting stage and entering the normal heating stage. Specifically, controlling the internal fan speed, external fan speed, and throttling device opening to adjust according to the preset values ​​of the third defrosting stage includes: controlling the internal fan to close, controlling the external fan to operate at a preset external fan first speed (the preset external fan first speed is greater than the preset external fan second speed, for example, the preset external fan first speed is the maximum external fan speed), and controlling the throttling device opening to decrease to a second preset opening (for example, 1 / 3 of the total opening).

[0066] The present invention also provides a storage medium corresponding to the defrosting control method of the air conditioner, wherein a computer program is stored thereon, and when the program is executed by a processor, the steps of any of the aforementioned methods are implemented.

[0067] The present invention also provides an air conditioner corresponding to the defrosting control method of the air conditioner, comprising a processor, a memory, and a computer program stored in the memory that can run on the processor, wherein the processor executes the program to implement the steps of any of the aforementioned methods.

[0068] The present invention also provides an air conditioner corresponding to the defrosting control device of the air conditioner, including the defrosting control device of any of the aforementioned air conditioners.

[0069] The present invention also provides a computer program product corresponding to the defrosting control method of the air conditioner, comprising a computer program that, when executed by a processor, implements the steps of any of the aforementioned methods.

[0070] Accordingly, the solution provided by the present invention adopts a method of first reducing the frequency and then switching the four-way valve to achieve rapid entry and exit of the defrost mode, shorten the time of reverse defrosting of the heat pump, and ensure a better defrosting effect of the air conditioner. At the same time, it is also beneficial to reduce the fluctuation range of system pressure and flow, and extend the working life of the compressor.

[0071] According to the technical solution of the present invention, using the exhaust pressure or intake pressure as the compressor frequency control condition during defrosting can better control the system's intake and exhaust pressures, which is beneficial to solving the problem of system pressure differences caused by different ambient temperatures, and has stronger commutation universality.

[0072] The functions described herein can be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions can be stored as one or more instructions or codes on or transmitted via a computer-readable medium. Other examples and embodiments are within the scope and spirit of this invention and the appended claims. For example, due to the nature of software, the functions described above can be implemented using software executed by a processor, hardware, firmware, hardwired, or any combination thereof. Furthermore, the functional units can be integrated into a single processing unit, or each unit can exist physically separately, or two or more units can be integrated into a single unit.

[0073] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0074] The units described as separate components may or may not be physically separate. Similarly, the components of the control device may or may not be physical units; they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0075] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to related technologies, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0076] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A defrosting control method for an air conditioner, characterized in that, include: When the air conditioner is in heating mode, it is determined whether the air conditioner meets the conditions for entering defrost. If the conditions for entering defrost are met, the first stage of defrost is entered. In the first defrosting stage, the compressor is controlled to operate at a preset frequency reduction rate. When the first preset condition is met, the compressor is controlled to stop reducing the frequency, and then the first defrosting stage is exited, and the second defrosting stage begins. In the second defrosting stage, the four-way valve is controlled to switch, and the compressor is controlled to increase the frequency at a preset frequency increase rate. When the suction pressure value is detected to be within the preset pressure value range and maintained for a second preset time, the compressor is controlled to stop increasing the frequency. When the second preset condition is met, the second defrosting stage is exited and the third defrosting stage is entered. In the third defrosting stage, the compressor is controlled to reduce its frequency at a preset rate. When the discharge pressure value drops to a safe reversing value and remains at that value for a third preset time, or when the time spent in the third defrosting stage reaches the preset maximum allowable time for the third stage, the compressor is controlled to stop reducing its frequency. Then, the four-way valve is controlled to reverse, exiting the third defrosting stage and continuing heating operation.

2. The method according to claim 1, characterized in that, Also includes: In the first stage of defrosting, the speed of the internal fan, the speed of the external fan, and the opening of the throttling device are adjusted according to the preset values ​​for the first stage of defrosting. The internal fan is controlled to operate at the preset first speed, the external fan is controlled to operate at the preset second speed, and the opening of the throttling device is reduced to the first preset opening.

3. The method according to claim 1, characterized in that, Also includes: In the second stage of defrosting, after the four-way valve is reversed, the opening of the throttling device is increased to the preset maximum opening, and the internal and external fans are shut down.

4. The method according to claim 1, characterized in that, Also includes: In the third stage of defrosting, after the four-way valve is reversed, the speed of the internal fan, the speed of the external fan, and the opening of the throttling device are adjusted according to the preset values ​​for the third stage of defrosting, and maintained for a fourth preset time before exiting the third stage of defrosting. The internal fan is shut down, the external fan is operated at the preset first speed, and the throttling device opening is reduced to the second preset opening.

5. The method according to any one of claims 1-4, characterized in that, The first preset condition includes at least one of the following conditions: The exhaust pressure value is reduced to a preset safe reversing value and maintained for a first preset time. The time for entering the first defrosting stage reaches the preset maximum allowable time for the first stage, and the compressor frequency is reduced to a preset minimum frequency value.

6. The method according to any one of claims 1-4, characterized in that, The second preset condition includes whether the outdoor ambient temperature, the outdoor heat exchanger temperature, and the defrosting time meet the preset conditions.

7. A defrosting control device for an air conditioner, characterized in that, include: The judgment unit is used to determine whether the air conditioner meets the defrosting conditions when the air conditioner is in heating mode, and when the defrosting conditions are met, the air conditioner enters the first stage of defrosting. The first control unit is used to control the compressor to reduce its frequency at a preset frequency reduction rate during the first defrosting stage. When the first preset condition is met, the control unit controls the compressor to stop reducing its frequency and then exits the first defrosting stage and enters the second defrosting stage. The second control unit is used to control the four-way valve to switch direction and control the compressor to increase the frequency at a preset frequency increase rate during the second defrosting stage. When the suction pressure value is detected to be within the preset pressure value range and maintained for a second preset time, the compressor is controlled to stop increasing the frequency. When the second preset condition is met, the second defrosting stage is exited and the third defrosting stage is entered. The third control unit is used to control the compressor to reduce its frequency at a preset rate during the third defrosting stage. When the discharge pressure value is detected to drop to a safe reversing value and remain at that value for a third preset time, or when the time spent in the third defrosting stage reaches the preset maximum allowable time for the third stage, the control unit controls the compressor to stop reducing its frequency and then controls the four-way valve to reverse, exiting the third defrosting stage and continuing heating operation.

8. A storage medium, characterized in that, It stores a computer program that, when executed by a processor, implements the steps of the method according to any one of claims 1-6.

9. An air conditioner, characterized in that, It includes a processor, a memory, and a computer program stored on the memory that can run on the processor, wherein the processor executes the program to implement the steps of any of the methods of claims 1-6, or includes a defrosting control device as described in claim 7.

10. A computer program product, characterized in that, Includes a computer program, which, when executed by a processor, implements the steps of the method according to any one of claims 1-6.

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