Dual-heat-pump system and defrosting control method for system

Abstract

The invention relates to a double-heat-pump system which comprises a controller, and the controller comprises a defrosting judgment control unit and a heating system frequency control unit. The defrosting judgment control unit is used for obtaining the coil pipe temperature of the first heat pump system and the coil pipe temperature of the second heat pump system if the first heat pump system and the second heat pump system both meet the defrosting condition, the heat pump system corresponding to the lower temperature value is controlled to enter a defrosting mode, and the other heat pump system needs to be in a heating mode. The heating system frequency control unit is used for obtaining the working frequency of the heat pump system in the defrosting mode at the current moment, obtaining the target working frequency of the heat pump system in the heating mode according to the working frequency, and controlling the working frequency of the heat pump system in the heating mode to be adjusted to the target working frequency. According to the double-heat-pump system, water temperature fluctuation is remarkably reduced, the comfort of a user is improved, the energy efficiency of the system is optimized, and the double-heat-pump system can adapt to different working conditions.

Description

Technical Field

[0001] This invention relates to the field of heat pump technology, and in particular to a dual heat pump system and a defrosting control method for the system. Background Art

[0002] A traditional dual heat pump system consists of two separate systems, each with its own compressor, reversing four-way valve, water-side heat exchanger, throttling device, and air-side heat exchanger. During winter heating operation, high-temperature, high-pressure refrigerant is delivered to the water-side heat exchanger via the compressor. The water-side heat exchanger acts as a condenser, exchanging heat with the user end, raising the user end temperature and lowering the refrigerant temperature. The low-temperature, high-pressure refrigerant then passes through the throttling device, transforming into low-temperature, low-pressure refrigerant, which is then delivered to the air-side heat exchanger. The air-side heat exchanger acts as an evaporator, exchanging heat with the external environment, lowering the ambient temperature and raising the refrigerant temperature. During this process, the surface temperature of the air-side heat exchanger is lower than the ambient temperature. When the dew point temperature is reached, frost forms on the surface of the air-side heat exchanger, affecting heating performance. To solve this problem, the two systems switch the refrigerant flow direction using a reversing four-way valve, turning the air-side heat exchanger from an evaporator into a condenser, allowing the high-temperature, high-pressure refrigerant to flow through it and remove surface water or frost.

[0003] In actual use, the defrosting mode of the dual-system unit is divided into three situations: 1) Both systems reach the defrosting conditions at the same time and enter the defrosting process together; 2) One system reaches the defrosting conditions and enters the defrosting process, while the other system continues to maintain heating; 3) One system reaches the defrosting conditions and enters the defrosting process, while the other system remains in the off state.

[0004] However, the defrosting process described above will cause significant fluctuations in the water temperature at the user end, affecting the user experience. Summary of the Invention

[0005] Therefore, the purpose of this invention is to overcome the defects or deficiencies of the prior art and provide a dual heat pump system.

[0006] A dual heat pump system includes a first heat pump system and a second heat pump system. The first heat pump system includes a first compressor, a first reversing four-way valve, a first water-side heat exchanger, a first throttling assembly, and a first air-side heat exchanger, all connected by a refrigerant circulation pipe. The second heat pump system includes a second compressor, a second reversing four-way valve, a second water-side heat exchanger, a second throttling assembly, and a second air-side heat exchanger, all connected by a refrigerant circulation pipe. The first water-side heat exchanger includes a first refrigerant flow channel and a first water flow channel, and the second water-side heat exchanger includes a second refrigerant flow channel and a second water flow channel. The first water flow channel and the second water flow channel each share a common flow path. It uses the same inlet and outlet; it also includes an ambient temperature sensor for the external environment where the first air-side heat exchanger and the second air-side heat exchanger are located; a first temperature sensor installed on the coil of the first air-side heat exchanger; and a second temperature sensor installed on the coil of the second air-side heat exchanger; it also includes a controller, which is electrically connected to the first compressor, the second compressor, the first reversing four-way valve, the second reversing four-way valve, the ambient temperature sensor, the first temperature sensor, and the second temperature sensor. The controller includes a defrost judgment control unit and a heating system frequency control unit.

[0007] The defrosting determination and control unit is used to obtain the first coil temperature T of the first air-side heat exchanger if both the first heat pump system and the second heat pump system meet the defrosting conditions. p1 The second coil temperature T of the second air-side heat exchanger p2 Control the temperature T of the first coil p1 Second coil temperature T p2 The heat pump system corresponding to the lower temperature value enters the defrost mode, while the other heat pump system needs to be in the heating mode.

[0008] The heating system frequency control unit is used to obtain the operating frequency F of the heat pump system currently in defrost mode. A And according to the operating frequency F A The target operating frequency of the heat pump system in heating mode is calculated. And control the operating frequency of the heat pump system in heating mode to adjust it to the target operating frequency.

[0009] Compared to existing technologies, the dual heat pump system described in this invention significantly reduces water temperature fluctuations, improves user comfort, and optimizes system energy efficiency, making it adaptable to different operating conditions.

[0010] In one embodiment, the defrosting determination and control unit is further configured to:

[0011] If neither the first heat pump system nor the second heat pump system has reached the defrosting condition and is in heating mode, then the operating mode of the first heat pump system and the second heat pump system will not be changed.

[0012] If the first heat pump system reaches the defrosting condition while the second heat pump system is in a shutdown state, the first heat pump system is controlled to enter the defrosting mode and the second heat pump system is started and operates in the heating mode.

[0013] If the first heat pump system reaches the defrosting condition but the second heat pump system does not, then the first heat pump system is controlled to enter the defrosting mode, while the second heat pump system continues to operate in the heating mode.

[0014] In one embodiment, according to the operating frequency F A The target operating frequency of the heat pump system in heating mode is calculated. include:

[0015]

[0016] Z0 is the operating frequency adjustment threshold, which is a fixed value.

[0017] In one embodiment, the value of the operating frequency adjustment threshold Z0 is determined based on the ambient temperature Ta, and specifically includes:

[0018] If Ta ≥ 0℃, Z0 takes the value of 0;

[0019] If 0℃>Ta≥-10℃, Z0 takes the value of 10;

[0020] If -10℃ > Ta ≥ -20℃, Z0 is taken as 20;

[0021] If -20℃ > Ta, then Z0 is 30.

[0022] In one embodiment, a defrost exit unit is further included, which is used to determine whether the heat pump system currently in defrost mode meets the defrost exit condition. If it does, the heat pump system in defrost mode immediately exits defrost, while another heat pump system in heating mode enters defrost mode.

[0023] In one embodiment, the defrosting conditions include determining the temperature T of the first coil. p1 Is it less than the first coil temperature threshold? Or the temperature of the second coil T p2 Is it less than the first coil temperature threshold? If the temperature of the first coil is T p1 Less than the first coil temperature threshold The first heat pump system meets the defrosting conditions if the temperature of the second coil is T. p2 Less than the first coil temperature threshold The second heat pump system then meets the defrosting requirements;

[0024] The defrosting exit condition includes determining the temperature T of the first coil. p1 Is it greater than or equal to the second coil temperature threshold? Or the temperature of the second coil T p2 Is it greater than or equal to the second coil temperature threshold? If the temperature of the first coil is T p1 Greater than or equal to the second coil temperature threshold The first heat pump system meets the defrost shutdown conditions if the second coil temperature T p2 Greater than or equal to the second coil temperature threshold The second heat pump system then meets the defrost shutdown conditions;

[0025] Among them, the second coil temperature threshold Temperature greater than the first coil temperature threshold

[0026] In one embodiment, the operating frequency of the first compressor is in the range of (35, 90); the operating frequency of the second compressor is in the range of (35, 90).

[0027] Furthermore, the present invention also provides a defrosting control method for a dual heat pump system, comprising the following steps:

[0028] S10 If both the first heat pump system and the second heat pump system meet the defrosting conditions, then obtain the first coil temperature T of the first air-side heat exchanger. p1 The second coil temperature T of the second air-side heat exchanger p2 Control the temperature T of the first coil p1 Second coil temperature T p2 The heat pump system corresponding to the lower temperature value enters the defrost mode, while the other heat pump system needs to be in the heating mode.

[0029] S20 obtains the current operating frequency F of the heat pump system in defrost mode. A And according to the operating frequency F A The target operating frequency of the heat pump system in heating mode is calculated. And control the operating frequency of the heat pump system in heating mode to adjust it to the target operating frequency.

[0030] S30 determines whether the heat pump system currently in defrost mode meets the defrost exit condition. If it does, the heat pump system in defrost mode immediately exits defrost, while another heat pump system in heating mode enters defrost mode.

[0031] In one embodiment, step S10 further includes:

[0032] If neither the first heat pump system nor the second heat pump system has reached the defrosting condition and is in heating mode, then the operating mode of the first heat pump system and the second heat pump system will not be changed.

[0033] If the first heat pump system reaches the defrosting condition while the second heat pump system is in a shutdown state, the first heat pump system is controlled to enter the defrosting mode and the second heat pump system is started and operates in the heating mode.

[0034] If the first heat pump system reaches the defrosting condition but the second heat pump system does not, then the first heat pump system is controlled to enter the defrosting mode, while the second heat pump system continues to operate in the heating mode.

[0035] In one embodiment, in step S20, the operating frequency F is determined... A The target operating frequency of the heat pump system in heating mode is calculated. include:

[0036]

[0037] Wherein, Z0 is the operating frequency adjustment threshold, which is a fixed value. The value of the operating frequency adjustment threshold Z0 is determined according to the ambient temperature Ta, and specifically includes:

[0038] If Ta ≥ 0℃, Z0 takes the value of 0;

[0039] If 0℃>Ta≥-10℃, Z0 takes the value of 10;

[0040] If -10℃ > Ta ≥ -20℃, Z0 is taken as 20;

[0041] If -20℃ > Ta, then Z0 is 30.

[0042] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the structure of the dual heat pump system provided by the present invention;

[0044] Figure 2 A schematic diagram of the components in the dual heat pump system controller provided by the present invention;

[0045] Figure 3 A flowchart of the defrosting control method provided by the present invention. Detailed Implementation

[0046] The present invention will now be described in detail with reference to the accompanying drawings.

[0047] like Figure 1 As shown, a dual heat pump system with defrost control according to the present invention includes a first heat pump system 10 and a second heat pump system 20. The first heat pump system 10 includes a first compressor 11, a first reversing four-way valve 12, a first water-side heat exchanger 13, a first throttling assembly 14, and a first air-side heat exchanger 15 connected by a refrigerant circulation pipe. The second heat pump system 20 includes a second compressor 21, a second reversing four-way valve 22, a second water-side heat exchanger 23, a second throttling assembly 24, and a second air-side heat exchanger 25 connected by a refrigerant circulation pipe. The first water-side heat exchanger 13 includes a first refrigerant flow channel 13A and a first water flow channel 13B. The second water-side heat exchanger 23 includes a second refrigerant flow channel 23A and a second water flow channel 23B. Water at the user end flows through the first water flow channel 13B and the second water flow channel 23B through the first water-side heat exchanger 13 and the second water-side heat exchanger 23 for heat exchange.

[0048] Specifically, when the first heat pump system 10 is in heating mode, high-temperature and high-pressure refrigerant is discharged from the first compressor 11 and output to the first water-side heat exchanger 13 through the first reversing four-way valve 12. In the first water-side heat exchanger 13, the water at the user end absorbs heat from the high-temperature and high-pressure refrigerant, causing the water temperature at the user end to rise while the refrigerant temperature decreases. Subsequently, the first throttling component 14 causes the refrigerant to change from a low-temperature and high-pressure liquid state to a low-temperature and low-pressure liquid state or a gas-liquid mixture. In the first air-side heat exchanger 15, the low-temperature and low-pressure refrigerant absorbs heat from the outside air, causing the low-temperature and low-pressure liquid state or gas-liquid mixture to change into a low-temperature and low-pressure gas. The low-temperature and low-pressure refrigerant then returns to the compressor through the first reversing four-way valve 12. Similarly, the operation process of the second heat pump system 20 in heating mode is as described above.

[0049] Specifically, when the first heat pump system 10 needs to defrost the surface of the first air-side heat exchanger 15, high-temperature and high-pressure refrigerant is discharged from the first compressor 11 and output to the first air-side heat exchanger 15 through the first reversing four-way valve 12. In the first air-side heat exchanger 15, the outside air absorbs heat from the high-temperature and high-pressure refrigerant, causing the outside air temperature to rise and thus melting the frost layer on the surface of the heat exchanger. Subsequently, the first throttling component 14 causes the refrigerant to change from a low-temperature and high-pressure liquid state to a low-temperature and low-pressure liquid state or a gas-liquid mixture. In the first water-side heat exchanger 13, the low-temperature and low-pressure refrigerant absorbs heat from the water at the user end, causing the water temperature at the user end to drop, and the refrigerant changes from a low-temperature and low-pressure liquid state or a gas-liquid mixture to a low-temperature and low-pressure gas state. The low-temperature and low-pressure refrigerant then returns to the compressor through the first reversing four-way valve 12. Similarly, the operation process of the second heat pump system 20 in defrosting mode is as described above.

[0050] Furthermore, it also includes an ambient temperature sensor 31 located in the external environment where the first air-side heat exchanger 15 and the second air-side heat exchanger 25 are located, for obtaining the ambient temperature Ta.

[0051] Furthermore, it also includes a controller 40, which is electrically connected to the first compressor 11, the second compressor 21, the first reversing four-way valve 12, the second reversing four-way valve 22, and the ambient temperature sensor 31.

[0052] like Figure 2 As shown, the controller 40 includes a defrost judgment control unit 41, a heating system frequency control unit 42, and a defrost exit unit 43.

[0053] The defrosting determination and control unit 41 is used to obtain the first coil temperature T of the first air-side heat exchanger 15 if both the first heat pump system 10 and the second heat pump system 20 meet the defrosting conditions. p1 The second coil temperature T of the second air-side heat exchanger 25 p2 Control the temperature T of the first coil p1 Second coil temperature T p2 The heat pump system corresponding to the lower temperature value enters the defrost mode, while the other heat pump system needs to be in the heating mode.

[0054] The heating system frequency control unit 42 is used to obtain the operating frequency F of the heat pump system in defrost mode at the current moment. A And according to the operating frequency F A The target operating frequency of the heat pump system in heating mode is calculated. And control the operating frequency of the heat pump system in heating mode to adjust it to the target operating frequency.

[0055] The defrost exit unit 43 is used to determine whether the heat pump system currently in defrost mode meets the defrost exit conditions. If it does, the heat pump system in defrost mode immediately exits defrost, while another heat pump system in heating mode enters defrost mode.

[0056] Specifically, the defrosting judgment and control unit 41 is also used for:

[0057] If neither the first heat pump system 10 nor the second heat pump system 20 has reached the defrosting condition and is in heating mode, then the operating mode of the first heat pump system 10 and the second heat pump system 20 will not be changed.

[0058] If the first heat pump system 10 reaches the defrosting condition while the second heat pump system 20 is in a shutdown state, then the first heat pump system 10 is controlled to enter the defrosting mode and the second heat pump system 20 is started and operates in the heating mode.

[0059] If the first heat pump system 10 meets the defrosting conditions but the second heat pump system 20 does not, then the first heat pump system 10 is controlled to enter the defrosting mode and the second heat pump system 20 continues to operate in the heating mode.

[0060] Specifically, according to the operating frequency F A The target operating frequency of the heat pump system in heating mode is calculated. include:

[0061]

[0062] Z0 is the operating frequency adjustment threshold, which is a fixed value.

[0063] Specifically, the value of the operating frequency adjustment threshold Z0 is determined based on the ambient temperature Ta, and includes the following:

[0064] If Ta ≥ 0℃, Z0 takes the value of 0;

[0065] If 0℃>Ta≥-10℃, Z0 takes the value of 10;

[0066] If -10℃ > Ta ≥ -20℃, Z0 is taken as 20;

[0067] If -20℃ > Ta, then Z0 is 30.

[0068] Specifically, the defrosting conditions include determining the temperature T of the first coil. p1 Is it less than the first coil temperature threshold? Or the temperature of the second coil T p2 Is it less than the first coil temperature threshold? If the temperature of the first coil is T p1 Less than the first coil temperature threshold Then the first heat pump system 10 meets the defrosting conditions, if the temperature of the second coil T p2 Less than the first coil temperature threshold Then the second heat pump system 20 meets the defrosting conditions;

[0069] The defrosting exit condition includes determining the temperature T of the first coil. p1 Is it greater than or equal to the second coil temperature threshold? Or the temperature of the second coil T p2 Is it greater than or equal to the second coil temperature threshold? If the temperature of the first coil is T p1 Greater than or equal to the second coil temperature threshold Then the first heat pump system 10 meets the defrost exit condition, if the second coil temperature T p2 Greater than or equal to the second coil temperature threshold Then the second heat pump system 20 meets the defrost exit conditions;

[0070] Among them, the second coil temperature threshold Temperature greater than the first coil temperature threshold

[0071] Specifically, the operating frequency of the first compressor 11 ranges from (35, 90); the operating frequency of the second compressor 21 ranges from (35, 90).

[0072] In addition, if Figure 3 As shown, the present invention also provides a defrosting control method for a dual heat pump system, comprising the following steps:

[0073] S10 If both the first heat pump system 10 and the second heat pump system 20 meet the defrosting conditions, then obtain the first coil temperature T of the first air-side heat exchanger 15. p1 The second coil temperature T of the second air-side heat exchanger 25 p2 Control the temperature T of the first coil p1 Second coil temperature T p2 The heat pump system corresponding to the lower temperature value enters the defrost mode, while the other heat pump system needs to be in the heating mode.

[0074] S20 obtains the current operating frequency F of the heat pump system in defrost mode. A And according to the operating frequency F A The target operating frequency of the heat pump system in heating mode is calculated. And control the operating frequency of the heat pump system in heating mode to adjust it to the target operating frequency.

[0075] S30 determines whether the heat pump system currently in defrost mode meets the defrost exit condition. If it does, the heat pump system in defrost mode immediately exits defrost, while another heat pump system in heating mode enters defrost mode.

[0076] Specifically, step S10 also includes:

[0077] If neither the first heat pump system 10 nor the second heat pump system 20 has reached the defrosting condition and is in heating mode, then the operating mode of the first heat pump system 10 and the second heat pump system 20 will not be changed.

[0078] If the first heat pump system 10 reaches the defrosting condition while the second heat pump system 20 is in a shutdown state, then the first heat pump system 10 is controlled to enter the defrosting mode and the second heat pump system 20 is started and operates in the heating mode.

[0079] If the first heat pump system 10 meets the defrosting conditions but the second heat pump system 20 does not, then the first heat pump system 10 is controlled to enter the defrosting mode and the second heat pump system 20 continues to operate in the heating mode.

[0080] Specifically, in step S20, according to the operating frequency F A The target operating frequency of the heat pump system in heating mode is calculated. include:

[0081]

[0082] Wherein, Z0 is the operating frequency adjustment threshold, which is a fixed value. The value of the operating frequency adjustment threshold Z0 is determined according to the ambient temperature Ta, and specifically includes:

[0083] If Ta ≥ 0℃, Z0 takes the value of 0;

[0084] If 0℃>Ta≥-10℃, Z0 takes the value of 10;

[0085] If -10℃ > Ta ≥ -20℃, Z0 is taken as 20;

[0086] If -20℃ > Ta, then Z0 is 30.

[0087] Compared to existing technologies, by optimizing the defrosting method of the dual-system heat pump system, water temperature fluctuations are significantly reduced, user comfort is improved, and system energy efficiency is optimized, making it adaptable to different operating conditions.

[0088] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments and claims of this application are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that, unless otherwise stated, “a plurality” means two or more; the terms “first,” “second,” “third,” etc., are used only to distinguish and not to describe a particular order or sequence, nor should they be construed as indicating or implying relative importance. The term “and / or” as used herein refers to and includes any or all possible combinations of one or more associated listed items. When the above description relates to drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. In the description of this application, those skilled in the art will understand the specific meaning of the above terms in this application according to the specific circumstances.

[0089] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A dual heat pump system, comprising a first heat pump system and a second heat pump system, wherein the first heat pump system includes a first compressor, a first reversing four-way valve, a first water-side heat exchanger, a first throttling assembly, and a first air-side heat exchanger connected by a refrigerant circulation pipe; and the second heat pump system includes a second compressor, a second reversing four-way valve, a second water-side heat exchanger, a second throttling assembly, and a second air-side heat exchanger connected by a refrigerant circulation pipe; wherein, The first water-side heat exchanger includes a first refrigerant flow channel and a first water flow channel; the second water-side heat exchanger includes a second refrigerant flow channel and a second water flow channel, the first water flow channel and the second water flow channel sharing the same inlet and outlet; it also includes an ambient temperature sensor installed in the external environment where the first air-side heat exchanger and the second air-side heat exchanger are located; a first temperature sensor installed on the coil of the first air-side heat exchanger; and a second temperature sensor installed on the coil of the second air-side heat exchanger; it also includes a controller, the controller being electrically connected to the first compressor, the second compressor, the first reversing four-way valve, the second reversing four-way valve, the ambient temperature sensor, the first temperature sensor, and the second temperature sensor, characterized in that: The controller includes a defrost detection control unit and a heating system frequency control unit; The defrosting determination and control unit is used to obtain the first coil temperature T of the first air-side heat exchanger if both the first heat pump system and the second heat pump system meet the defrosting conditions. p1 The second coil temperature T of the second air-side heat exchanger p2 Control the temperature T of the first coil p1 Second coil temperature T p2 The heat pump system corresponding to the lower temperature value enters the defrost mode, while the other heat pump system needs to be in the heating mode. The heating system frequency control unit is used to obtain the operating frequency F of the heat pump system currently in defrost mode. A And according to the operating frequency F of the heat pump system in defrost mode A The target operating frequency of the heat pump system in heating mode is calculated. And control the operating frequency of the heat pump system in heating mode to adjust it to the target operating frequency.

2. The dual heat pump system according to claim 1, characterized in that, The defrosting judgment and control unit is also used for: If neither the first heat pump system nor the second heat pump system has reached the defrosting condition and is in heating mode, then the operating mode of the first heat pump system and the second heat pump system will not be changed. If the first heat pump system reaches the defrosting condition while the second heat pump system is in a shutdown state, the first heat pump system is controlled to enter the defrosting mode and the second heat pump system is started and operates in the heating mode. If the first heat pump system reaches the defrosting condition but the second heat pump system does not, then the first heat pump system is controlled to enter the defrosting mode, while the second heat pump system continues to operate in the heating mode.

3. The dual heat pump system according to claim 2, characterized in that, According to the operating frequency F of the heat pump system in defrost mode A The target operating frequency of the heat pump system in heating mode is calculated. include: Z0 is the operating frequency adjustment threshold, which is a fixed value.

4. The dual heat pump system according to claim 3, characterized in that: The value of the operating frequency adjustment threshold Z0 is determined based on the ambient temperature Ta, and specifically includes: If Ta ≥ 0℃, Z0 takes the value of 0; If 0℃>Ta≥-10℃, Z0 takes the value of 10; If -10℃ > Ta ≥ -20℃, Z0 is taken as 20; If -20℃ > Ta, then Z0 is 30.

5. The dual heat pump system according to claim 1, characterized in that: It also includes a defrost exit unit, which is used to determine whether the heat pump system currently in defrost mode meets the defrost exit conditions. If it does, the heat pump system in defrost mode immediately exits defrost, while another heat pump system in heating mode enters defrost mode.

6. The dual heat pump system according to claim 5, characterized in that: The defrosting conditions include determining the temperature T of the first coil. p1 Is it less than the first coil temperature threshold? Or the temperature of the second coil T p2 Is it less than the first coil temperature threshold? If the temperature of the first coil is T p1 Less than the first coil temperature threshold The first heat pump system meets the defrosting conditions if the temperature of the second coil is T. p2 Less than the first coil temperature threshold The second heat pump system then meets the defrosting requirements; The defrosting exit condition includes determining the temperature T of the first coil. p1 Is it greater than or equal to the second coil temperature threshold? Or the temperature of the second coil T p2 Is it greater than or equal to the second coil temperature threshold? If the temperature of the first coil is T p1 Greater than or equal to the second coil temperature threshold The first heat pump system meets the defrost shutdown conditions if the second coil temperature T p2 Greater than or equal to the second coil temperature threshold The second heat pump system then meets the defrost shutdown conditions; Among them, the second coil temperature threshold Temperature greater than the first coil temperature threshold 7. The dual heat pump system according to claim 4, characterized in that: The operating frequency of the first compressor ranges from (35, 90); the operating frequency of the second compressor ranges from (35, 90).

8. A defrosting control method for a dual heat pump system, characterized in that, Includes the following steps: S10 If both the first heat pump system and the second heat pump system meet the defrosting conditions, then obtain the first coil temperature T of the first air-side heat exchanger. p1 The second coil temperature T of the second air-side heat exchanger p2 Control the temperature T of the first coil p1 Second coil temperature T p2 The heat pump system corresponding to the lower temperature value enters the defrost mode, while the other heat pump system needs to be in the heating mode. S20 obtains the current operating frequency F of the heat pump system in defrost mode. A And according to the operating frequency F of the heat pump system in defrost mode A The target operating frequency of the heat pump system in heating mode is calculated. And control the operating frequency of the heat pump system in heating mode to adjust it to the target operating frequency. S30 determines whether the heat pump system currently in defrost mode meets the defrost exit condition. If it does, the heat pump system in defrost mode immediately exits defrost, while another heat pump system in heating mode enters defrost mode.

9. The defrosting control method according to claim 8, characterized in that, Step S10 also includes: If neither the first heat pump system nor the second heat pump system has reached the defrosting condition and is in heating mode, then the operating mode of the first heat pump system and the second heat pump system will not be changed. If the first heat pump system reaches the defrosting condition while the second heat pump system is in a shutdown state, the first heat pump system is controlled to enter the defrosting mode and the second heat pump system is started and operates in the heating mode. If the first heat pump system reaches the defrosting condition but the second heat pump system does not, then the first heat pump system is controlled to enter the defrosting mode, while the second heat pump system continues to operate in the heating mode.

10. The defrosting control method according to any one of claims 8 or 9, characterized in that, In step S20, the operating frequency F of the heat pump system in defrost mode is used as a reference. A The target operating frequency of the heat pump system in heating mode is calculated. include: Wherein, Z0 is the operating frequency adjustment threshold, which is a fixed value. The value of the operating frequency adjustment threshold Z0 is determined according to the ambient temperature Ta, and specifically includes: If Ta ≥ 0℃, Z0 takes the value of 0; If 0℃>Ta≥-10℃, Z0 takes the value of 10; If -10℃ > Ta ≥ -20℃, Z0 is taken as 20; If -20℃ > Ta, then Z0 is 30.

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