Air conditioning system and control method thereof

Abstract

The application discloses an air conditioning system and a control method thereof. The air conditioning system comprises a first heat exchanger circuit, a second heat exchanger circuit, a first sub-heat exchange circuit, a first heat exchanger and a control module. The first heat exchanger circuit comprises a first outdoor heat exchanger and a first four-way valve, and the second heat exchanger circuit comprises a second outdoor heat exchanger and a second four-way valve. When the first outdoor heat exchanger needs to defrost, the first four-way valve is controlled to change direction, and the valve position of the second four-way valve remains unchanged, so that the first heat exchanger circuit enters a refrigeration defrosting mode, and the second heat exchanger circuit remains in a heating mode. The low-temperature refrigerant flowing out of the first outdoor heat exchanger does not affect the overall heating of the air conditioning system, the heating effect of the air conditioning system can be ensured, continuous heating of the air conditioning system in the defrosting mode is realized, temperature fluctuation of a user side during defrosting is avoided, and user comfort is improved.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, and in particular to an air conditioning system and its control method. Background Technology

[0002] During heating operation, the surface temperature of the heat exchanger in an air conditioning unit may drop below zero degrees Celsius, leading to frost formation. Frost increases the thermal resistance of the heat exchanger, reducing heat exchange efficiency and affecting the overall reliability of the unit. Therefore, air conditioning units require defrosting after a period of heating operation. Current technology typically involves switching the air conditioning unit from heating to cooling mode. In cooling mode, the heat exchanger temperature rises, achieving the defrosting function. However, this defrosting method prevents the air conditioning unit from heating, resulting in significant temperature fluctuations at the user's location and impacting the user experience. Summary of the Invention

[0003] In view of this, the present invention provides an air conditioning system and its control method to achieve continuous heating of the air conditioning system during the defrosting process, avoid temperature fluctuations on the user side, and improve user comfort.

[0004] In a first aspect, embodiments of the present invention provide an air conditioning system, including a first heat exchanger circuit, a second heat exchanger circuit, a first sub-heat exchanger circuit, a first heat exchanger, and a control module; The first heat exchanger circuit includes a first compressor, a first four-way valve, a first outdoor heat exchanger, a first indoor heat exchanger, and a first gas-liquid separator that are connected to each other; the second heat exchanger circuit includes a second compressor, a second four-way valve, a second outdoor heat exchanger, a second indoor heat exchanger, and a second gas-liquid separator that are connected to each other. The first heat exchanger circuit further includes a first node and a second node. The first node is located in the connection path between the first outdoor heat exchanger and the first indoor heat exchanger, and the second node is close to the air inlet end of the first gas-liquid separator. One end of the first sub-heat exchange circuit is connected to the first node, and the other end of the first sub-heat exchange circuit is connected to the second node. The first heat exchanger is located in the first sub-heat exchange circuit. The control module is electrically connected to the first four-way valve and the second four-way valve. When the air conditioning system meets the first defrosting condition, the control module controls the first four-way valve to switch direction and controls the valve position of the four-way valve to remain unchanged, so that the first heat exchanger circuit performs defrosting work and the second heat exchanger circuit continues to perform heating work.

[0005] Secondly, embodiments of the present invention also provide a control method for an air conditioning system, applied to the air conditioning system provided in the embodiments of the present invention, the control method comprising: When the air conditioning system meets the first defrosting condition, the first four-way valve is controlled to switch direction, and the valve position of the second four-way valve is controlled to remain unchanged, so that the first heat exchanger circuit performs defrosting operation, and the second heat exchanger circuit continues to perform heating operation.

[0006] The air conditioning system provided in this embodiment of the invention, when the air conditioning system meets the first defrosting condition, controls the first four-way valve to switch direction and keeps the valve position of the second four-way valve unchanged, so that the first heat exchanger circuit performs defrosting work, while the second heat exchanger circuit continues to perform heating work. Using the above scheme, when the first outdoor heat exchanger needs defrosting, the first heat exchanger circuit is controlled to enter the cooling defrosting mode, while the second heat exchanger circuit remains in the heating mode. Since the low-temperature refrigerant in the first heat exchanger circuit 1 no longer flows into the first indoor heat exchanger, but directly returns to the first gas-liquid separator via the first heat exchanger, the low-temperature refrigerant flowing out of the first outdoor heat exchanger will not affect the overall heating of the air conditioning system, ensuring the heating effect of the air conditioning system, thereby achieving continuous heating of the air conditioning system in defrosting mode, avoiding temperature fluctuations on the user side during defrosting, and improving user comfort. Attached Figure Description

[0007] Figure 1 A schematic diagram of an air conditioning system provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of another air conditioning system provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of another air conditioning system provided in an embodiment of the present invention; Figure 4 A flowchart of an air conditioning control method provided in an embodiment of the present invention; Figure 5 This is a control logic diagram of a control method for an air conditioning system provided in an embodiment of the present invention. Detailed Implementation

[0008] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0009] To address the issue of temperature fluctuations during defrosting in air conditioning systems, this invention proposes an air conditioning system. Figure 1 This is a schematic diagram of an air conditioning system provided in an embodiment of the present invention, which can be referred to. Figure 1The air conditioning system consists of a first heat exchanger loop 1, a second heat exchanger loop 2, a first sub-heat exchanger loop 3, a first heat exchanger 4, and a control module (not shown in the figure). The first heat exchanger loop 1 includes a first compressor 10, a first four-way valve 11, a first outdoor heat exchanger 12, a first indoor heat exchanger 13, and a first gas-liquid separator 14, all interconnected. The second heat exchanger loop 2 includes a second compressor 20, a second four-way valve 21, a second outdoor heat exchanger 22, a second indoor heat exchanger 23, and a second gas-liquid separator 24, all interconnected. The first heat exchanger loop 1 includes a first node 1a and a second node 1b. The first node 1a is located in the connection path between the first outdoor heat exchanger 12 and the first indoor heat exchanger 13, and the second node 1b is near the air inlet of the first gas-liquid separator 14. One end of the first sub-heat exchanger loop 3 is connected to the first node 1a, and the other end is connected to the second node 1b. The first heat exchanger 4 is located within the first sub-heat exchanger loop 3. The control module is electrically connected to the first four-way valve 11 and the second four-way valve 21. When the air conditioning system meets the first defrosting condition, it controls the first four-way valve 11 to switch and controls the valve position of the second four-way valve 21 to remain unchanged, so that the first heat exchanger circuit 1 performs defrosting and the second heat exchanger circuit 2 continues to perform heating.

[0010] In this embodiment of the invention, at least two heat exchanger loops are provided in the air conditioning system. Each heat exchanger loop is equipped with components such as a compressor, a four-way valve, an outdoor heat exchanger, an indoor heat exchanger, and a gas-liquid separator. This embodiment is described with the first heat exchanger loop 1 and the second heat exchanger loop 2 both having a quantity of 1, but the actual implementation is not limited to this. Figure 1 Different circuits are distinguished by lines of varying thickness, but this does not represent the actual structure.

[0011] In heating mode, both the first four-way valve 11 and the second four-way valve 21 are in the heating indicator position. In this position, the first port A and the second port B of the first four-way valve 11 (or the second four-way valve 21) are connected, as are the third port C and the fourth port D. Both heat exchanger circuits operate together for heating, utilizing the first outdoor heat exchanger 12 and the second outdoor heat exchanger 22 for heat exchange. The first outdoor heat exchanger 12 and the second outdoor heat exchanger 22 can be finned heat exchangers. Finned heat exchangers are more prone to frosting in heating mode. This air conditioning system can defrost the first outdoor heat exchanger 12 and / or the second outdoor heat exchanger 22 under normal heating conditions.

[0012] Furthermore, to achieve continuous heating during defrosting, a first sub-heat exchange loop 3 and a first heat exchanger 4 are additionally provided in the air conditioning system. The first sub-heat exchange loop 3 is connected in parallel with a portion of the first sub-heat exchange loop 3 through a first node 1a and a second node 1b. The first heat exchanger 4 includes a first fluid channel 40, which is located in the first sub-heat exchange loop 3. The following is a brief description of the refrigerant flow in the normal heating mode of the air conditioning system. Normal heating mode can be understood as the mode where the air conditioning system heats without requiring defrosting. The control module controls the first four-way valve 11 in the first heat exchanger circuit 1 to be in the heating position. The high-temperature, high-pressure refrigerant from the outlet of the first compressor 10 enters the first indoor heat exchanger 13 after passing through the first four-way valve 11 and condenses into a medium-temperature, high-pressure liquid refrigerant. Then, it is throttled by the electronic expansion valve in the first heat exchanger circuit 1 into a low-temperature, low-pressure gas-liquid two-phase refrigerant. This gas then exchanges heat with the outdoor air in the first outdoor heat exchanger 12, evaporating into a low-temperature, low-pressure gaseous refrigerant. Finally, the refrigerant flows through the first four-way valve 11 into the first gas-liquid separator 14, where it is separated into gaseous and liquid states. The gaseous refrigerant returns to the first compressor 10 for recirculation. The control logic and refrigerant flow direction of the second heat exchanger circuit 2 are similar to those of the first heat exchanger circuit 1, and will not be described further here.

[0013] Furthermore, the first defrosting condition can be a condition that needs to be met when the first outdoor heat exchanger 12 needs to defrost. For example, the first defrosting condition can be that the surface temperature of the first outdoor heat exchanger 12 is lower than a preset temperature, but it is not limited to this. Those skilled in the art can set it according to actual needs. In the present invention, in the heating mode of the air conditioning system, the control module can determine whether the system meets the first defrosting condition, and when the system meets the first defrosting condition, it controls the first four-way valve 11 in the first heat exchanger circuit 1 to be placed in the cooling flag position, and the second four-way valve 21 in the second heat exchanger circuit 2 to remain in the heating flag position. At the same time, it can also adjust the first compressor 10 to operate at the defrosting frequency. Figure 1 The first four-way valve 11 is in the cooling position, with the second port B and the third port C connected, and the first port A and the fourth port D connected; the second four-way valve 21 is in the heating position.

[0014] When the first four-way valve 11 reverses, the refrigerant flow direction in the first heat exchanger circuit 1 changes, specifically as follows: the high-temperature, high-pressure gaseous refrigerant compressed by the first compressor 10 enters the first outdoor heat exchanger 12 through the first four-way valve 11, heating and defrosting the first outdoor heat exchanger 12, and the refrigerant condenses into a high-temperature, high-pressure liquid refrigerant at the first outdoor heat exchanger 12. The refrigerant flowing out of the first outdoor heat exchanger 12 reaches the first node 1a. At this time, the control module controls the refrigerant to enter the first heat exchanger 4, not the first indoor heat exchanger 13; the refrigerant entering the first sub-heat exchange circuit 3 flows through the first heat exchanger 4 to the second node 1b, and then enters the first gas-liquid separator 14 through the second node 1b, and the gaseous refrigerant returns to the first compressor 10 to recirculate. Meanwhile, the second four-way valve 21 remains in the heating position. The high-temperature and high-pressure gaseous refrigerant, after being compressed by the second compressor 20, enters the second indoor heat exchanger 23 through the second four-way valve 21 and exchanges heat with the outdoor air in the second outdoor heat exchanger 22. The second indoor heat exchanger 23 continuously raises the indoor temperature and maintains the overall heating function of the air conditioning system. Subsequently, the refrigerant enters the second outdoor heat exchanger 22 and exchanges heat with the outdoor air. Finally, it enters the second gas-liquid separator 24 through the second four-way valve 21, and the gaseous refrigerant returns to the second compressor 20 to recirculate.

[0015] This configuration means that when the first outdoor heat exchanger 12 needs defrosting, the first heat exchanger circuit 1 enters the cooling defrosting mode, while the second heat exchanger circuit 2 remains in heating mode. Since the low-temperature refrigerant in the first heat exchanger circuit 1 no longer flows into the first indoor heat exchanger 13, but instead returns directly to the first gas-liquid separator 14 via the first heat exchanger 4, the low-temperature refrigerant flowing out of the first outdoor heat exchanger 12 will not affect the overall heating performance of the air conditioning system. This ensures the heating effect of the air conditioning system, thereby achieving continuous heating in defrosting mode, avoiding temperature fluctuations on the user side during defrosting, and improving user comfort.

[0016] The type of the first heat exchanger 4 is not limited. Those skilled in the art can set it according to actual needs. For example, the first heat exchanger 4 can be a plate heat exchanger, such as an economizer, but it is not limited to this. Any heat exchanger that can perform the function of the first heat exchanger 4 in this invention is within the scope of the technical solution protected by the embodiments of this invention.

[0017] Optionally, conventional components such as filter 5 may also be installed in the air conditioning circuit, but this invention does not elaborate on or limit this.

[0018] Using the above scheme, when the first outdoor heat exchanger needs defrosting, the first heat exchanger circuit is controlled to enter the cooling defrosting mode, while the second heat exchanger circuit remains in heating mode. Since the low-temperature refrigerant in the first cooling circuit no longer flows into the first indoor heat exchanger but directly returns to the first gas-liquid separator, the low-temperature refrigerant flowing out of the first outdoor heat exchanger will not affect the overall heating performance of the air conditioning system. This ensures the heating effect of the air conditioning system, thereby achieving continuous heating in defrosting mode, avoiding temperature fluctuations on the user side during defrosting, and improving the user experience.

[0019] Optional, Figure 2 This is a schematic diagram of another air conditioning system provided in an embodiment of the present invention, which can be referred to. Figure 2 In this embodiment of the invention, the first heat exchanger 4 may include a first fluid channel 40 and a second fluid channel 41. The first fluid channel 40 is located in the first sub-heat exchange loop 3, and the second fluid channel 41 is located in the connection path between the second outdoor heat exchanger 22 and the second indoor heat exchanger 23 in the second heat exchanger loop 2. The first indoor heat exchanger 13 can be reused as the second indoor heat exchanger 23. The first indoor heat exchanger 13 includes a first air inlet 13a, a second air inlet 13b, a first air outlet 13c, and a second air outlet 13d. The first air inlet 13a is connected to the first node 1a, the first air outlet 13c is connected to the first four-way valve 11, the second air inlet 13b is connected to the second outdoor heat exchanger 22 through the second fluid channel 41, and the second air outlet 13d... The system is connected to the second four-way valve 21. The air conditioning system also includes a first electronic expansion valve 15, a second electronic expansion valve 30, and a third electronic expansion valve 25. The first electronic expansion valve 15 is located in the connection path between the first outdoor heat exchanger 12 and the first air inlet 13a. The second electronic expansion valve 30 is located in the connection path between the first node 1a and the first heat exchanger 4. The third electronic expansion valve 25 is located in the connection path between the second outdoor heat exchanger 22 and the first heat exchanger 4. The control module is also used to electrically connect the first electronic expansion valve 15, the second electronic expansion valve 30, and the third electronic expansion valve 25. The control module is also used to control the first electronic expansion valve 15 to close and the second electronic expansion valve 30 and the third electronic expansion valve 25 to open when the air conditioning system meets the first defrosting condition.

[0020] like Figure 2 As shown, in this embodiment, the first heat exchanger 4 can also be located in the second heat exchanger loop 2. The first fluid channel 40 of the first heat exchanger 4 is located in the connection path between the first outdoor heat exchanger 12 and the first gas-liquid separator 14. The second fluid channel 41 of the first heat exchanger 4 is located in the second heat exchanger loop 2 and in the connection path between the second outdoor heat exchanger 22 and the second indoor heat exchanger 23. The refrigerant in the first fluid channel 40 and the refrigerant in the second fluid channel 41 can exchange heat at the first heat exchanger 4.

[0021] Furthermore, in this embodiment, the air conditioning system may only have one indoor heat exchanger, which is shared by the first heat exchanger circuit 1 and the second heat exchanger circuit 2. For example, taking the reuse of the first indoor heat exchanger 13 as an example, the first indoor heat exchanger 13 includes two air inlets and two air outlets. The first air inlet 13a and the first air outlet 13c are located in the first heat exchanger circuit 1 and are used to connect the first outdoor heat exchanger 12 and the first port A of the first four-way valve 11. The second air inlet 13b and the second air outlet 13d are located in the second heat exchanger circuit 2 and are used to connect the second outdoor heat exchanger 22 and the first port A of the second four-way valve 21.

[0022] Continue to refer to Figure 2 A first electronic expansion valve 15, a second electronic expansion valve 30, and a third electronic expansion valve 25 are respectively installed in the first heat exchanger circuit 1, the first sub-heat exchanger circuit 3, and the second heat exchanger circuit 2. The first electronic expansion valve 15 is located between the first node 1a and the first air inlet 13a, the second electronic expansion valve 30 is located between the first node 1a and the first fluid channel 40 of the first heat exchanger 4, and the third electronic expansion valve 25 is located between the second outdoor heat exchanger 22 and the second fluid channel 41 of the first heat exchanger 4. The first electronic expansion valve 15, the second electronic expansion valve 30, and the third electronic expansion valve 25 are used to regulate the flow path of the refrigerant.

[0023] In this configuration, if the control module determines that the air conditioning system meets the first defrosting condition, it can simultaneously control the first four-way valve 11 to switch, and simultaneously control the first electronic expansion valve 15 to close and the second electronic expansion valve 30 and the third electronic expansion valve 25 to open. This allows the refrigerant flowing from the first outdoor heat exchanger 12 to enter the first sub-heat exchange circuit 3, and then flow into the first heat exchanger 4 via the second electronic expansion valve 30, no longer entering the first indoor heat exchanger 13. Correspondingly, the refrigerant circulation flow in the second heat exchanger circuit 2 is as follows: second compressor 20, second four-way valve 21, second outlet 13d of the first indoor heat exchanger 13, second inlet 13b of the first indoor heat exchanger 13, first heat exchanger 4, third electronic expansion valve 25, second outdoor heat exchanger 22, second four-way valve 21, second gas-liquid separator 24.

[0024] It should be noted that the air inlet or outlet of a component specified in the embodiments of the present invention is only used to define the structure of the component, and not to limit the direction of refrigerant flow. The refrigerant can flow from the air inlet to the air outlet, or from the air outlet to the air inlet.

[0025] In this embodiment, by connecting the first heat exchanger 4 to the second heat exchanger circuit 2, during the defrosting process of the first outdoor heat exchanger 12, the liquid refrigerant entering the first fluid channel 40 of the first heat exchanger 4 exchanges heat with the medium-temperature and high-pressure liquid refrigerant entering the second fluid channel 41 and turns into gas. Then, after passing through the first gas-liquid separator 14, it returns to the suction port of the first compressor 10, which can prevent the first compressor 10 from carrying liquid and ensure the reliability of the air conditioning system.

[0026] Optionally, in other possible embodiments, when the first defrosting condition is met, the control module may also simultaneously control the opening of the first electronic expansion valve 15 and the second electronic expansion valve 30, and adjust the flow rate of the refrigerant entering the first heat exchanger 4 and the first indoor heat exchanger 13 through the first node 1a by controlling the opening degree of the first electronic expansion valve 15 and the second electronic expansion valve 30, so as to adjust the pressure of the first heat exchanger circuit 1 and the first sub-heat exchange circuit 3 and ensure that the circuit pressure is kept within the normal range.

[0027] Optional, Figure 3 This is a schematic diagram of another air conditioning system provided in an embodiment of the present invention. Figure 3 The first heat exchanger circuit 1 in the air conditioning system shown above is related to the above Figure 2 The illustrated embodiment is the same, and the first heat exchanger loop 1 and the second heat exchanger loop 2 still share a single indoor heat exchanger. The difference lies in the arrangement of the second heat exchanger loop 2, see reference [link to relevant documentation]. Figure 3 In this embodiment, the second heat exchanger circuit 2 includes a main heat exchange circuit 26 and a second sub-heat exchange circuit 27. The main heat exchange circuit 26 includes a second compressor 20, a second four-way valve 21, a second outdoor heat exchanger 22, a first indoor heat exchanger 13 (second indoor heat exchanger 23), and a second gas-liquid separator 24 connected in sequence. The main heat exchange circuit 26 also includes a third node 26a and a fourth node 26b. The third node 26a is located in the connection path between the second outdoor heat exchanger 22 and the first indoor heat exchanger 13 (second indoor heat exchanger 23), and the fourth node 26b is located near the inlet end of the second gas-liquid separator 24. One end of the second sub-heat exchange circuit 27 is connected to the third node 26a, and the other end of the second sub-heat exchange circuit 27 is connected to the fourth node 26b, so as to be connected in parallel with a portion of the main heat exchange circuit 26. The second fluid channel 41 of the first heat exchanger 4 is located in the second sub-heat exchange circuit 27.

[0028] Furthermore, a fourth electronic expansion valve 28 is provided in the main heat exchange circuit 26 between the second outdoor heat exchanger 22 and the first indoor heat exchanger 13, and a fifth electronic expansion valve 29 is provided in the second sub-heat exchange circuit 27 between the second outdoor heat exchanger 22 and the first heat exchanger 4.

[0029] If the control module detects that one of the outdoor heat exchangers (taking the second outdoor heat exchanger 22 as an example) needs defrosting, it can control the second four-way valve 21 in the second heat exchanger circuit 2 to switch (set to the cooling indicator), the fourth electronic expansion valve 28 to close, and the fifth electronic expansion valve 29 to open. The refrigerant circulation direction in the second heat exchanger circuit 2 is: second compressor 20, second four-way valve 21, second outdoor heat exchanger 22, fifth electronic expansion valve 29, first heat exchanger 4, fourth node 26b, and second gas-liquid separator 24. At the same time, it controls the first four-way valve 11 in the first heat exchanger circuit 1 to remain in the same position (set to the heating indicator), the first electronic expansion valve 15 in the first heat exchanger circuit 1 to open, and the second electronic expansion valve 30 in the first sub-heat exchanger circuit 3 to close. The refrigerant circulation flow in the first heat exchanger circuit 1 is as follows: first compressor 10, first four-way valve 11, first outlet 13c of the first indoor heat exchanger 13, first inlet 13a of the first indoor heat exchanger 13, first electronic expansion valve 15, first outdoor heat exchanger 12, first four-way valve 11, and first gas-liquid separator 14. This ensures that while defrosting the second outdoor heat exchanger 22, the first indoor heat exchanger 13 continuously heats the indoor environment. The control logic for defrosting the first outdoor heat exchanger 12 is similar and will not be elaborated here.

[0030] Further references are available. Figure 1 In this embodiment of the invention, the air conditioning system may be equipped with a first temperature sensor 6 and an ambient temperature sensor 7. The first temperature sensor 6 is located on the first outdoor heat exchanger 12 and is used to detect the first temperature of the first outdoor heat exchanger 12 in real time. The ambient temperature sensor 7 is used to detect the ambient temperature in real time. A control module (not shown in the figure) is electrically connected to the first temperature sensor 6 and the ambient temperature sensor 7 respectively. The control module is also used to determine whether the air conditioning system meets the first defrosting condition based on the first temperature, the ambient temperature, and the defrosting time interval. The defrosting time interval is the time interval between the end time of the last defrosting operation and the current time.

[0031] Specifically, such as Figure 1 As shown, the first temperature sensor 6 can be located on the outer casing of the first outdoor heat exchanger 12. It is used to detect the first temperature of the first outdoor heat exchanger 12 (e.g., the surface temperature of the casing) in real time and send the first temperature to the control module. The setting of the ambient temperature sensor 7 is not limited. The location of the ambient temperature sensor 7 shown in the figure is only an example and does not represent the actual situation. It can be understood that the ambient temperature sensor 7 can be set outdoors to monitor the ambient temperature in real time. The ambient temperature sensor 7 sends the detected ambient temperature to the control module.

[0032] The control module acquires a first temperature based on the first temperature sensor 6 and a second temperature based on the ambient temperature sensor 7. The control module can also record the time when the air conditioning system last defrosted. If this is the first defrost operation, the time when the air conditioning system last defrosted is the start-up time.

[0033] Furthermore, this embodiment proposes an optional method for determining the first defrosting condition. Specifically, the first defrosting condition may include three determination targets: the first determination target is T≤Ta, where T is the ambient temperature and Ta is the ambient temperature threshold; the second determination target is T-T1≥Tb, where T1 is the first temperature and Tb is the defrosting temperature difference threshold; and the third determination target is... , This is the threshold value for the time interval between the last defrosting end time and the current time. This represents the defrosting time interval threshold. It should be noted that the current time refers to the moment when the above-mentioned determination objective is executed, which can be understood as the real-time moment.

[0034] It is understandable that an ambient temperature less than or equal to an ambient temperature threshold indicates that the current air conditioning system is in heating mode; a difference between the ambient temperature and the first temperature greater than or equal to the defrost temperature difference threshold indicates that the temperature of the first outdoor heat exchanger 12 is low; and a time interval threshold greater than or equal to the defrost time interval threshold indicates that there has been a certain interval since the last defrost. When all three of the above criteria are met simultaneously, it can be determined that the air conditioning system meets the first defrost condition.

[0035] Using three criteria to determine whether to perform defrosting can improve the accuracy of the first defrosting condition judgment. This ensures that defrosting is performed in a timely manner when the system needs it, and also avoids frequent defrosting from affecting the overall performance of the machine.

[0036] In this embodiment of the invention, the specific values ​​of the above-mentioned ambient temperature threshold, defrosting temperature difference threshold, and defrosting time interval threshold are not limited, and can be set by those skilled in the art according to the actual situation during the production and research and development process.

[0037] Optionally, the above embodiments illustrate the defrosting process of the first outdoor heat exchanger 12. In other possible embodiments, the air conditioning system may also defrost the second outdoor heat exchanger 22.

[0038] Specifically, the control module can also be used to control the second four-way valve 21 to switch direction when the air conditioning system meets the second defrosting conditions, and control the valve position of the first four-way valve 11 to remain unchanged, so that the second heat exchanger circuit 2 performs defrosting work and the first heat exchanger circuit 1 continues to perform heating work.

[0039] The second defrosting condition can be a condition that needs to be met when the second outdoor heat exchanger 22 needs to defrost. For example, the second defrosting condition can be that the surface temperature of the second outdoor heat exchanger 22 is lower than a preset temperature, but it is not limited to this. Those skilled in the art can set it according to actual needs. In this embodiment, when the preset time after the first outdoor heat exchanger 12 finishes defrosting is reached, the control module can determine whether the system meets the second defrosting condition. When the system meets the second defrosting condition, it controls the second four-way valve 21 to be placed in the cooling flag position and the first four-way valve 11 to remain in the heating flag position. At the same time, it can also adjust the second compressor 20 to run at the defrosting frequency. This allows the second heat exchanger circuit 2 to be used for cooling and defrosting while maintaining heating.

[0040] Figure 1 In the embodiment shown, when the second four-way valve 21 reverses, the third electronic expansion valve 25 is opened. The high-temperature and high-pressure gaseous refrigerant in the second heat exchanger circuit 2, after being compressed by the second compressor 20, enters the second outdoor heat exchanger 22 through the second four-way valve 21 to heat up and defrost the second outdoor heat exchanger 22. Subsequently, the refrigerant returns to the second compressor 20 through the second indoor heat exchanger 23, the second four-way valve 21, and the second gas-liquid separator 24. Figure 2 In the embodiment shown, when the second four-way valve 21 reverses, the third electronic expansion valve 25 is opened. The high-temperature and high-pressure gaseous refrigerant in the second heat exchanger circuit 2, after being compressed by the second compressor 20, enters the second outdoor heat exchanger 22 through the second four-way valve 21 to heat up and defrost the second outdoor heat exchanger 22. Subsequently, the refrigerant returns to the second compressor 20 through the first heat exchanger 4, the second indoor heat exchanger 23, the second four-way valve 21, and the second gas-liquid separator 24. Figure 3 In the illustrated embodiment, when the second four-way valve 21 reverses, it controls the fourth electronic expansion valve 28 to close and the fifth electronic expansion valve 29 to open. The high-temperature and high-pressure gaseous refrigerant in the second heat exchanger circuit 2, after being compressed by the second compressor 20, enters the second outdoor heat exchanger 22 through the second four-way valve 21 to heat up and defrost the second outdoor heat exchanger 22. Subsequently, the refrigerant returns to the second compressor 20 through the fifth electronic expansion valve 29, the first heat exchanger 4, and the second gas-liquid separator 24.

[0041] Meanwhile, the first heat exchanger circuit 1 continues to generate heat, and the control module controls the first electronic expansion valve 15 to open and the second electronic expansion valve 30 to close. The refrigerant flow in the second heat exchanger circuit 2 is as follows: first compressor 10, first four-way valve 11, first indoor heat exchanger 13, first electronic expansion valve 15, first outdoor heat exchanger 12, first four-way valve 11, first gas-liquid separator 14, and finally the gaseous refrigerant returns to the first compressor 10 and continues to circulate along the above path.

[0042] Optional, you can continue to refer to Figure 1In a possible embodiment, the air conditioning system may further include a second temperature sensor 8, a first pressure sensor 91, and a second pressure sensor 92. The second temperature sensor 8 is located on the second outdoor heat exchanger 22 and is used to detect the second temperature of the second outdoor heat exchanger 22. The first pressure sensor 91 is located in the first heat exchanger circuit 1 and is used to detect the first pressure in the first heat exchanger circuit 1. The second pressure sensor 92 is located in the second heat exchanger circuit 2 and is used to detect the second pressure in the second heat exchanger circuit 2. The control module (not shown in the figure) is also electrically connected to the second temperature sensor 8, the first pressure sensor 91, and the second pressure sensor 92, respectively. The control module is also used to determine whether the air conditioning system meets the second defrosting conditions based on the first temperature, the second temperature, the first pressure, and the second pressure.

[0043] Specifically, the second temperature sensor 8 can be installed on the outer casing of the second outdoor heat exchanger 22 to detect the second temperature of the second outdoor heat exchanger 22 in real time (e.g., the surface temperature of the casing) and send the second temperature to the control module. The first pressure sensor 91 can be installed in the connection path between the first gas-liquid separator 14 and the first compressor 10 to detect the first pressure in the first heat exchanger circuit 1 in real time and send the first pressure to the control module; the second pressure sensor 92 can be installed in the connection path between the second gas-liquid separator 24 and the second compressor 20 to detect the second pressure in the second heat exchanger circuit 2 in real time and send the second pressure to the control module.

[0044] The control module obtains the second temperature based on the second temperature sensor 8, the first pressure based on the first pressure sensor 91, and the second pressure based on the second pressure sensor 92. Based on the ambient temperature, the second temperature, the defrosting time interval, the first pressure, and the second pressure, the control module determines whether the second outdoor heat exchanger 22 meets the second defrosting conditions.

[0045] Furthermore, this embodiment proposes an optional method for determining the second defrosting condition. Specifically, the second defrosting condition may include four determination targets: the first determination target is T≤Ta, where T is the ambient temperature and Ta is the ambient temperature threshold; the second determination target is T-T2≥Tb, where T2 is the second temperature and Tb is the defrosting temperature difference threshold; the third determination target is... The fourth criterion is P1-P2≥Pa, where P1 is the first pressure, P2 is the second pressure, and Pa is the pressure difference threshold. When all four criteria are met simultaneously, the air conditioning system is deemed to meet the second defrosting condition. The defrosting time interval is also specified. Defrosting time interval threshold The determination method can be the same as in the above embodiments, which is the time interval threshold between the last defrosting end time of the first outdoor heat exchanger 12 (not the defrosting end time of the first outdoor heat exchanger 12 this time) and the current time.

[0046] It is understandable that an ambient temperature less than or equal to an ambient temperature threshold indicates that the current air conditioning system is in heating mode, and a difference between the ambient temperature and the second temperature greater than or equal to the defrost temperature difference threshold indicates that the temperature of the second outdoor heat exchanger 22 is low. It is worth noting that in this embodiment, a pressure difference judgment target is further added. It is understood that when the outdoor heat exchanger is heavily frosted, the heat exchange effect is poor, and the evaporation pressure is relatively low; conversely, the evaporation pressure is high. After the first outdoor heat exchanger 12 has defrosted, the first pressure of the first heat exchanger circuit 1 should be relatively high. If the second outdoor heat exchanger 22 is severely frosted at this time, the second pressure in the second heat exchanger circuit 2 should be very low, and the difference between the first and second pressures will be relatively large. Therefore, when the difference between the first and second pressures is greater than or equal to the pressure difference threshold, it indicates that the second outdoor heat exchanger 22 is severely frosted. Using this as the fourth judgment target can further improve the accuracy of the defrost condition judgment for the second outdoor heat exchanger 22, avoiding the situation where the second outdoor heat exchanger 22 is severely frosted but does not enter defrost mode due to system abnormalities.

[0047] In this embodiment of the invention, the specific setting of the differential pressure threshold is not limited and can be set by those skilled in the art according to the actual situation during the production and research and development process.

[0048] Optional, you can continue to refer to Figure 1 The first outdoor heat exchanger 12 and the second outdoor heat exchanger 22 can be installed in close proximity; the air conditioning system is also equipped with a fan, which is located on the side of the second outdoor heat exchanger 22 away from the first outdoor heat exchanger 12.

[0049] When defrosting the first outdoor heat exchanger 12, a fan can be started. Since the first outdoor heat exchanger 12 and the second indoor heat exchanger 23 are in close contact, the temperature of the first outdoor heat exchanger 12 is transferred to the second outdoor heat exchanger 22, thus utilizing the heat from the first outdoor heat exchanger 12 to simultaneously defrost the second outdoor heat exchanger 22. The presence of the fan accelerates the heat transfer between the two. This setup reduces the frequency of defrosting the second outdoor heat exchanger 22, which helps save system power consumption.

[0050] Based on the same concept, the present invention also provides a control method for an air conditioning system, applicable to the air conditioning system provided in any embodiment of the present invention, the structure of which can be referred to the above. Figures 1-3 The embodiment shown will not be described in detail here. The control method includes: when the air conditioning system meets the first defrosting condition, controlling the first four-way valve 11 to switch, and controlling the valve position of the second four-way valve 21 to remain unchanged, so that the first heat exchanger circuit 1 performs defrosting work, and the second heat exchanger circuit 2 continues to perform heating work.

[0051] The first defrosting condition can be any condition that the first outdoor heat exchanger 12 needs to be defrosted. For example, the first defrosting condition can be that the surface temperature of the first outdoor heat exchanger 12 is lower than a preset temperature, but it is not limited to this. Those skilled in the art can set it according to actual needs. In this invention, in the heating mode of the air conditioning system, the control module can determine whether the system meets the first defrosting condition. When the system meets the first defrosting condition, it controls the first four-way valve 11 to be in the cooling flag position and the second four-way valve 21 to remain in the heating flag position. At the same time, it can also adjust the first compressor 10 to operate at the defrosting frequency.

[0052] refer to Figure 1 , Figure 2 or Figure 3 When the first four-way valve 11 reverses, the refrigerant flow direction in the first heat exchanger circuit 1 changes, specifically as follows: the high-temperature, high-pressure gaseous refrigerant compressed by the first compressor 10 enters the first outdoor heat exchanger 12 through the first four-way valve 11, heating and defrosting the first outdoor heat exchanger 12, and the refrigerant condenses into a high-temperature, high-pressure liquid refrigerant at the first outdoor heat exchanger 12. The refrigerant flowing out of the first outdoor heat exchanger 12 reaches the first node 1a. At this time, the control module controls the refrigerant to enter the first sub-heat exchange circuit 3, and not the first indoor heat exchanger 13; the refrigerant entering the first sub-heat exchange circuit 3 flows through the first heat exchanger 4 to the second node 1b, and then enters the first gas-liquid separator 14 through the second node 1b, and the gaseous refrigerant returns to the first compressor 10 to recirculate.

[0053] Since the low-temperature refrigerant in the first heat exchanger circuit 1 no longer flows into the first indoor heat exchanger 13, but directly returns to the first gas-liquid separator 14 via the first heat exchanger 4, the low-temperature refrigerant flowing out of the first outdoor heat exchanger 12 will not affect the overall heating of the air conditioning system, thus ensuring the heating effect of the air conditioning system and enabling continuous heating of the air conditioning system in defrosting mode. This avoids temperature fluctuations on the user side during defrosting and improves user comfort.

[0054] The control method for the air conditioning system provided in this embodiment of the invention includes all the technical features and corresponding beneficial effects of the air conditioning system provided in any embodiment of the invention, which will not be repeated here. For any aspects of the control method not detailed in the embodiments, please refer to the above system embodiments.

[0055] Optional, you can continue to refer to Figure 2The first heat exchanger 4 includes a first fluid channel 40 and a second fluid channel 41. The first fluid channel 40 is located in the first sub-heat exchange loop 3, and the second fluid channel 41 is located in the connection path between the second outdoor heat exchanger 22 and the second indoor heat exchanger 23 in the second heat exchanger loop 2. The first indoor heat exchanger 13 is reused as the second indoor heat exchanger 23. The first indoor heat exchanger 13 includes a first air inlet 13a, a second air inlet 13b, a first air outlet 13c, and a second air outlet 13d. The first air inlet 13a is connected to the first node 1a, the first air outlet 13c is connected to the first four-way valve 11, and the second air inlet 13b is connected to the second fluid channel 41. Channel 41 is connected to the second outdoor heat exchanger 22, and the second air outlet 13d is connected to the second four-way valve 21; the air conditioning system also includes a first electronic expansion valve 15, a second electronic expansion valve 30, and a third electronic expansion valve 25. The first electronic expansion valve 15 is located in the connection path between the first outdoor heat exchanger 12 and the first air inlet 13a, the second electronic expansion valve 30 is located in the connection path between the first node 1a and the first heat exchanger 4, and the third electronic expansion valve 25 is located in the connection path between the second outdoor heat exchanger 22 and the first heat exchanger 4; the control module is also used for electrical connection of the first electronic expansion valve 15, the second electronic expansion valve 30, and the third electronic expansion valve 25 respectively.

[0056] The control method of the air conditioning system includes: when the air conditioning system meets the first defrosting condition, controlling the first four-way valve 11 to switch, keeping the valve position of the second four-way valve 21 unchanged, and controlling the first electronic expansion valve 15 to close, while the second electronic expansion valve 30 and the third electronic expansion valve 25 to open, so that the first heat exchanger circuit 1 performs defrosting work, and the second heat exchanger circuit 2 continues to perform heating work.

[0057] If the control module determines that the air conditioning system meets the first defrosting condition, it can simultaneously control the first four-way valve 11 to switch direction, and control the first electronic expansion valve 15 to close and the second electronic expansion valve 30 and the third electronic expansion valve 25 to open. This allows the refrigerant flowing from the first outdoor heat exchanger 12 to enter the first sub-heat exchange circuit 3, and then flow into the first heat exchanger 4 via the second electronic expansion valve 30, no longer entering the first indoor heat exchanger 13. Correspondingly, the refrigerant circulation flow in the second heat exchanger circuit 2 is as follows: second compressor 20, second four-way valve 21, second outlet 13d of the first indoor heat exchanger 13, second inlet 13b of the first indoor heat exchanger 13, first heat exchanger 4, third electronic expansion valve 25, second outdoor heat exchanger 22, second four-way valve 21, second gas-liquid separator 24.

[0058] Optional, you can continue to refer to Figure 1 The air conditioning system may also include a first temperature sensor 6 and an ambient temperature sensor 7; the first temperature sensor 6 is located on the first outdoor heat exchanger 12 and is used to detect the first temperature of the first outdoor heat exchanger 12, and the ambient temperature sensor 7 is used to detect the ambient temperature.

[0059] When the air conditioning system also includes a first temperature sensor 6 and an ambient temperature sensor 7, before executing the control flow in the above embodiment, the following can also be performed: acquiring the first temperature and ambient temperature based on the first temperature sensor 6 and the ambient temperature sensor 7, and simultaneously acquiring the defrost time interval; the defrost time interval is the time interval between the end time of the last defrost operation and the current time; and: the ambient temperature, the first temperature, and the defrost time interval satisfy: T≤Ta, T-T1≥Tb, and At that time, it is determined that the air conditioning system meets the first defrosting condition; where T is the ambient temperature, Ta is the ambient temperature threshold, and T1 is the first temperature. This is the defrosting interval. This is the defrosting time interval threshold.

[0060] Figure 4 A flowchart of an air conditioning control method provided in an embodiment of the present invention is shown below. Figure 4 The control method includes the following steps: S101. Obtain the first temperature and the ambient temperature based on the first temperature sensor and the ambient temperature sensor, and at the same time obtain the defrosting time interval.

[0061] The first temperature sensor 6 detects the first temperature of the first outdoor heat exchanger 12 in real time and sends the first temperature to the control module; the ambient temperature sensor 7 monitors the ambient temperature in real time and sends the detected ambient temperature to the control module. Simultaneously, the control module can record the time when the air conditioning system last defrosted, thus obtaining the time interval between the end time of the last defrosting operation and the current time.

[0062] S102, Under the conditions of ambient temperature, initial temperature, and defrosting time interval: T≤Ta, T-T1≥Tb, and At that time, it was determined that the air conditioning system met the first defrosting condition.

[0063] The first defrosting condition may include three decision objectives: the first objective is T≤Ta, the second objective is T-T1≥Tb, and the third objective is... When all three criteria mentioned above are met simultaneously, the air conditioning system can be determined to meet the first defrosting condition.

[0064] S103. When the air conditioning system meets the first defrosting condition, control the first four-way valve to switch direction and control the valve position of the second four-way valve to remain unchanged, so that the first heat exchanger circuit performs defrosting work and the second heat exchanger circuit continues to perform heating work.

[0065] The specific implementation method of this step is the same as that in the above embodiments, and will not be repeated here.

[0066] Optional, you can continue to refer to Figure 1 When the air conditioning system also includes a second temperature sensor 8, a first pressure sensor 91, and a second pressure sensor 92; the second temperature sensor 8 is located on the second outdoor heat exchanger 22 and is used to detect the second temperature of the second outdoor heat exchanger 22; the first pressure sensor 91 is located in the first heat exchanger circuit 1 and is used to detect the first pressure in the first heat exchanger circuit 1; the second pressure sensor 92 is located in the second heat exchanger circuit 2 and is used to detect the second pressure in the second heat exchanger circuit 2.

[0067] The control method provided by this invention may further include: acquiring a second temperature, a first pressure, and a second pressure based on a second temperature sensor 8, a first pressure sensor 91, and a second pressure sensor 92; when the air conditioning system meets the first defrosting condition, controlling the first four-way valve 11 to switch direction and controlling the valve position of the second four-way valve 21 to remain unchanged, so that the first heat exchanger circuit 1 performs defrosting work and the second heat exchanger circuit 2 continues to perform heating work, and may further include the following two steps: Step 1: After a preset delay, when the ambient temperature, the second temperature, the first pressure, the second pressure, and the defrosting time interval satisfy: T≤Ta, T-T2≥Tb, When P1-P2≥Pa, the air conditioning system is determined to meet the second defrosting condition; where T2 is the second temperature, P1 is the first pressure, P2 is the second pressure, and Pa is the pressure difference threshold; Step 2: When the air conditioning system meets the second defrosting condition, the second four-way valve 21 is switched, and the valve position of the first four-way valve 11 is kept unchanged, so that the second heat exchanger circuit 2 performs defrosting work, and the first heat exchanger circuit 1 continues to perform heating work.

[0068] Specifically, when the preset time after the defrosting of the first outdoor heat exchanger 12 is reached, the control module can also obtain the second temperature based on the second temperature sensor 8, the first pressure based on the first pressure sensor 91, and the second pressure based on the second pressure sensor 92, and jointly determine whether the second outdoor heat exchanger 22 meets the second defrosting conditions based on the ambient temperature, the second temperature, the defrosting time interval, the first pressure, and the second pressure.

[0069] The second defrosting condition may include four decision objectives: the first objective is T≤Ta, the second objective is T-T2≥Tb, and the third objective is... The fourth criterion is P1-P2≥Pa. When all four criteria are met, the air conditioning system can be determined to meet the second defrosting condition.

[0070] When the air conditioning system meets the second defrosting condition, the control module controls the first four-way valve 11 to maintain the heating flag position, and the second four-way valve 21 to switch to the cooling flag position, so that the second heat exchanger circuit 2 can be used for cooling defrosting and the first heat exchanger circuit 1 can maintain heating.

[0071] Further optionally, when the air conditioning system meets the first defrosting condition, the first four-way valve 11 is controlled to switch, and the valve position of the second four-way valve 21 is kept unchanged, so that the first heat exchanger circuit 1 performs defrosting work and the second heat exchanger circuit 2 continues to perform heating work. Then, when the first temperature reaches the defrosting end temperature or the current defrosting duration reaches the defrosting duration threshold, the first four-way valve 11 is controlled to switch again, so that the first heat exchanger circuit 1 continues to perform heating work.

[0072] Specifically, in this embodiment, a defrosting end condition can be set, which may include: T1 ≥ Tc or t1 = t2; where T1 is the first temperature, Tc is the defrosting end temperature, t1 is the defrosting time, and t2 is the defrosting duration threshold. The control module can pre-store the defrosting end temperature and the defrosting duration threshold. The defrosting end temperature is the temperature at which the outdoor heat exchanger does not require defrosting, and the defrosting duration threshold can be understood as the time required to perform one defrosting operation. The defrosting end temperature and the defrosting duration threshold can be set by those skilled in the art during the production and development stage according to actual conditions; this invention does not limit or elaborate on this.

[0073] During the defrosting process of the first outdoor heat exchanger 12, when the control module detects that the air conditioning system meets any of the above defrosting end conditions, it can switch the valve position of the first four-way valve 11 back to the heating flag position, and the first heat exchanger circuit 1 continues to perform heating work.

[0074] Correspondingly, the defrosting end conditions of the second outdoor heat exchanger 22 can be adapted by referring to the defrosting end conditions of the first outdoor heat exchanger 12, which will not be described in detail here.

[0075] For example, Figure 5 This is a control logic diagram of a control method for an air conditioning system provided in an embodiment of the present invention, combined with... Figure 5 This paper provides an overall overview of the control methods for air conditioning systems. When the air conditioner is running in heating mode, it determines whether the first defrosting condition is met. The first defrosting condition is: T≤Ta, T-T2≥Tb, and... T, T1, Ta, Tb and The explanation is as described in the above embodiment. Further, when the first defrosting condition is met, the first compressor is controlled to operate at the defrosting frequency, the first electronic expansion valve is closed, the second electronic expansion valve is opened, and then the first four-way valve is reversed, the first heat exchanger circuit operates in cooling mode to defrost the first outdoor heat exchanger, and the second heat exchanger circuit continues to heat; if the first defrosting condition is not met, the first and second heat exchanger circuits maintain heating operation. Further, it is determined whether the defrosting end condition is met. The defrosting end condition is: T1 ≥ Tc or t1 = t2, and the explanations of Tc, t1, and t2 are as described in the above embodiment. If the defrosting end condition is met, the first four-way valve is controlled to reverse again, the first heat exchanger circuit ends defrosting, and both the first and second heat exchanger circuits operate in heating mode; if the defrosting condition is not met, the first heat exchanger circuit continues defrosting. After defrosting of the first heat exchanger loop is completed, a preset time is elapsed before determining whether the second defrosting condition is met. The second defrosting condition is: T≤Ta, T-T2≥Tb. The explanations for P1-P2≥Pa, T2, P1, P2, and Pa are as described in the above embodiments. If the second defrosting condition is met, the second four-way valve is switched, the second heat exchanger circuit operates in cooling mode, and the first heat exchanger circuit continues to heat; if the second defrosting condition is not met, the second heat exchanger circuit continues to heat.

[0076] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. An air conditioning system, characterized in that, It includes a first heat exchanger loop, a second heat exchanger loop, a first sub-heat exchanger loop, a first heat exchanger, and a control module; The first heat exchanger circuit includes a first compressor, a first four-way valve, a first outdoor heat exchanger, a first indoor heat exchanger, and a first gas-liquid separator that are connected to each other; the second heat exchanger circuit includes a second compressor, a second four-way valve, a second outdoor heat exchanger, a second indoor heat exchanger, and a second gas-liquid separator that are connected to each other. The first heat exchanger circuit further includes a first node and a second node. The first node is located in the connection path between the first outdoor heat exchanger and the first indoor heat exchanger, and the second node is close to the air inlet end of the first gas-liquid separator. One end of the first sub-heat exchange circuit is connected to the first node, and the other end of the first sub-heat exchange circuit is connected to the second node. The first heat exchanger is located in the first sub-heat exchange circuit. The control module is electrically connected to the first four-way valve and the second four-way valve. When the air conditioning system meets the first defrosting condition, the control module controls the first four-way valve to switch and controls the valve position of the second four-way valve to remain unchanged, so that the first heat exchanger circuit performs defrosting work and the second heat exchanger circuit continues to perform heating work. The first heat exchanger includes a first fluid channel and a second fluid channel. The first fluid channel is located in the first sub-heat exchange loop, and the second fluid channel is located in the connection path between the second outdoor heat exchanger and the second indoor heat exchanger in the second heat exchanger loop. The first indoor heat exchanger is reused as the second indoor heat exchanger. The first indoor heat exchanger includes a first air inlet, a second air inlet, a first air outlet, and a second air outlet. The first air inlet is connected to the first node, the first air outlet is connected to the first four-way valve, the second air inlet is connected to the second outdoor heat exchanger through the second fluid channel, and the second air outlet is connected to the second four-way valve. The air conditioning system further includes a first electronic expansion valve, a second electronic expansion valve, and a third electronic expansion valve. The first electronic expansion valve is located in the connection path between the first outdoor heat exchanger and the first air inlet. The second electronic expansion valve is located in the connection path between the first node and the first heat exchanger. The third electronic expansion valve is located in the connection path between the second outdoor heat exchanger and the first heat exchanger. The control module is also used to electrically connect to the first electronic expansion valve, the second electronic expansion valve and the third electronic expansion valve respectively. The control module is also used to control the first electronic expansion valve to close and the second electronic expansion valve and the third electronic expansion valve to open when the air conditioning system meets the first defrosting condition. The refrigerant in the first fluid channel and the refrigerant in the second fluid channel exchange heat at the first heat exchanger.

2. The air conditioning system according to claim 1, characterized in that, It also includes a first temperature sensor and an ambient temperature sensor; the first temperature sensor is located on the first outdoor heat exchanger and is used to detect the first temperature of the first outdoor heat exchanger in real time, and the ambient temperature sensor is used to detect the ambient temperature in real time. The control module is electrically connected to the first temperature sensor and the ambient temperature sensor respectively. The control module is also used to determine whether the air conditioning system meets the first defrosting condition based on the first temperature, the ambient temperature and the defrosting time interval; wherein, the defrosting time interval is the time interval between the end time of the last defrosting operation and the current time.

3. The air conditioning system according to claim 2, characterized in that, The control module is also used to control the second four-way valve to switch direction and control the valve position of the first four-way valve to remain unchanged when the air conditioning system meets the second defrosting condition, so that the second heat exchanger circuit performs defrosting work and the first heat exchanger circuit continues to perform heating work.

4. The air conditioning system according to claim 3, characterized in that, It also includes a second temperature sensor, a first pressure sensor, and a second pressure sensor; the second temperature sensor is located on the second outdoor heat exchanger and is used to detect the second temperature of the second outdoor heat exchanger. The first pressure sensor is located in the first heat exchanger circuit and is used to detect the first pressure in the first heat exchanger circuit. The second pressure sensor is located in the second heat exchanger circuit and is used to detect the second pressure in the second heat exchanger circuit. The control module is also electrically connected to the second temperature sensor, the first pressure sensor and the second pressure sensor respectively. The control module is also used to determine whether the air conditioning system meets the second defrosting condition based on the ambient temperature, the second temperature, the first pressure and the second pressure.

5. The air conditioning system according to claim 1, characterized in that, The first outdoor heat exchanger and the second outdoor heat exchanger are fitted together. The air conditioning system also includes a fan, which is located on the side of the second outdoor heat exchanger away from the first outdoor heat exchanger.

6. A control method for an air conditioning system, characterized in that, Applicable to the above claims The control method of the air conditioning system according to any one of the claims includes: When the air conditioning system meets the first defrosting condition, the first four-way valve is controlled to switch direction, and the valve position of the second four-way valve is controlled to remain unchanged, so that the first heat exchanger circuit performs defrosting operation, and the second heat exchanger circuit continues to perform heating operation.

7. The control method according to claim 6, characterized in that, When the air conditioning system includes a first temperature sensor and an ambient temperature sensor; Before controlling the first four-way valve to switch direction and controlling the valve position of the second four-way valve to remain unchanged when the air conditioning system meets the first defrosting condition, the method further includes: The first temperature and the ambient temperature are obtained based on the first temperature sensor and the ambient temperature sensor, and the defrosting time interval is also obtained; the defrosting time interval is the time interval between the end time of the last defrosting operation and the current time. The ambient temperature, the first temperature, and the defrosting time interval satisfy the following: , and When the air conditioning system meets the first defrosting condition, it is determined that T is the ambient temperature. Where T1 is the ambient temperature threshold, Tb is the first temperature, and Tb is the defrosting temperature difference threshold. The defrosting time interval is... This is the defrosting time interval threshold.

8. The control method according to claim 7, characterized in that, When the air conditioning system further includes a second temperature sensor, a first pressure sensor, and a second pressure sensor; The control method further includes: The second temperature, the first pressure, and the second pressure are obtained based on the second temperature sensor, the first pressure sensor, and the second pressure sensor; When the air conditioning system meets the first defrosting condition, the first four-way valve is controlled to switch direction, and the valve position of the second four-way valve is kept unchanged, so that the first heat exchanger circuit performs defrosting operation. After the second heat exchanger circuit continues to perform heating operation, the system further includes: After a preset delay, the ambient temperature, the second temperature, the first pressure, the second pressure, and the defrosting time interval satisfy the following: , , as well as When T2 is reached, it is determined that the air conditioning system meets the second defrosting condition; wherein, T2 is the second temperature, P1 is the first pressure, P2 is the second pressure, and Pa is the pressure difference threshold. When the air conditioning system meets the second defrosting condition, the second four-way valve is controlled to switch direction, and the valve position of the first four-way valve is kept unchanged, so that the second heat exchanger circuit performs defrosting operation, while the first heat exchanger circuit continues to perform heating operation.

9. The control method according to claim 7, characterized in that, When the air conditioning system meets the first defrosting condition, the first four-way valve is controlled to switch direction, and the valve position of the second four-way valve is kept unchanged, so that the first heat exchanger circuit performs defrosting operation. After the second heat exchanger circuit continues to perform heating operation, the system further includes: When the first temperature reaches the defrosting end temperature or the defrosting duration reaches the defrosting duration threshold, the first four-way valve is controlled to switch again, so that the first heat exchanger circuit continues to perform heating work.

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