Control method of air conditioning system, air conditioner

Abstract

The application provides a control method of an air conditioning system and an air conditioner, wherein the control method of the air conditioning system comprises the following steps: the air conditioning system operates in a heating mode; when a first outdoor heat exchanger reaches a defrosting condition, the opening degree of a first electronic expansion valve is controlled so that the outer surface temperature of the first outdoor heat exchanger is above the freezing point temperature, and the opening degree of a second electronic expansion valve is controlled so that the second outdoor heat exchanger keeps normal heating; or when the second outdoor heat exchanger reaches the defrosting condition, the opening degree of the second electronic expansion valve is controlled so that the outer surface temperature of the second outdoor heat exchanger is above the freezing point temperature, and the opening degree of the first electronic expansion valve is controlled so that the first outdoor heat exchanger keeps normal heating. According to the application, during the whole defrosting process, one outdoor heat exchanger is always in normal heating, and the other outdoor heat exchanger is defrosted in the case of participating in the heating of the air conditioning system, so the indoor environment temperature basically does not fluctuate, and therefore the comfort of people is not affected.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of air conditioners, and particularly relates to a control method of an air conditioning system and an air conditioner. BACKGROUND

[0002] When the outside temperature is low, the outdoor heat exchanger is easy to frost when the air conditioner is heating in low temperature conditions, and the frost will affect the heat exchange effect of the heat exchanger, so it is necessary to defrost the outdoor heat exchanger. The traditional defrosting methods include reverse cycle defrosting and hot gas bypass defrosting. When reverse cycle defrosting is adopted, the air conditioner stops heating, and the compressor delivers high-temperature and high-pressure refrigerant to the outdoor heat exchanger to defrost the outdoor heat exchanger by using the heat of the refrigerant. Hot gas bypass defrosting is to deliver part of the heat generated by the air conditioner heating to the outdoor heat exchanger for defrosting. As can be seen, both of the defrosting methods will cause large fluctuations in the indoor environment temperature, thereby affecting people's comfort. SUMMARY

[0003] Therefore, the present application provides a control method of an air conditioning system, which can overcome the problem that the outdoor heat exchanger of the air conditioner is easy to frost when heating in low temperature conditions, and the traditional reverse cycle defrosting and hot gas bypass defrosting will cause large fluctuations in the indoor environment temperature, thereby affecting people's comfort.

[0004] In order to solve the above problems, the present application provides a control method of an air conditioning system for controlling the operation of the air conditioning system, the air conditioning system comprising a first outdoor heat exchanger, a second outdoor heat exchanger, a first electronic expansion valve and a second electronic expansion valve, the first electronic expansion valve and the first outdoor heat exchanger forming a first flow path, the second electronic expansion valve and the second outdoor heat exchanger forming a second flow path, the first flow path and the second flow path being arranged in parallel, the control method comprising: the air conditioning system operating in a heating mode, when the first outdoor heat exchanger reaches a defrosting condition, controlling the opening degree of the first electronic expansion valve to make the outer surface temperature of the first outdoor heat exchanger reach above the freezing point temperature, and controlling the second electronic expansion valve and the second outdoor heat exchanger to remain in the working state in the heating mode; or when the second outdoor heat exchanger reaches a defrosting condition, controlling the opening degree of the second electronic expansion valve to make the outer surface temperature of the second outdoor heat exchanger reach above the freezing point temperature, and controlling the first electronic expansion valve and the first outdoor heat exchanger to remain in the working state in the heating mode.

[0005] In some embodiments, when the air conditioning system starts the heating mode, the opening degree of the first electronic expansion valve is controlled to make the outer surface temperature of the first outdoor heat exchanger reach below the freezing point temperature, and the opening degree of the second electronic expansion valve is controlled to make the outer surface temperature of the second outdoor heat exchanger reach above the freezing point temperature.

[0006] In some embodiments, when the air conditioning system starts the heating mode, the opening degree of the second electronic expansion valve is controlled to make the outer surface temperature of the second outdoor heat exchanger below the freezing point temperature, and the opening degree of the first electronic expansion valve is controlled to make the outer surface temperature of the first outdoor heat exchanger above the freezing point temperature.

[0007] In some embodiments, the defrosting condition comprises: an outside temperature Th < Ta, a difference between a temperature Tm1 at a first position of an outer surface of the first outdoor heat exchanger and a temperature T2 at an air inlet of the first outdoor heat exchanger is ΔT1, ΔT1 > Ts, a difference between a temperature Tm2 at a second position of an outer surface of the second outdoor heat exchanger and a temperature T4 at an air inlet of the second outdoor heat exchanger is ΔT2, ΔT2 > Ts, wherein Ta is a first preset value, and Ts is a second preset value.

[0008] In some embodiments, the defrosting condition further comprises: a duration Δt1 of ΔT1 > Ts exceeding a preset time ts, or a duration Δt2 of ΔT2 > Ts exceeding the preset time ts.

[0009] In some embodiments, the air conditioning system further comprises a reversing fan, when defrosting the first outdoor heat exchanger, the opening degree of the first electronic expansion valve is controlled to make the outer surface temperature of the first outdoor heat exchanger above the freezing point temperature and below the dew point temperature, and the air flow generated by the reversing fan flows from the first outdoor heat exchanger to the second outdoor heat exchanger.

[0010] In some embodiments, when defrosting the second outdoor heat exchanger, the opening degree of the second electronic expansion valve is controlled to make the outer surface temperature of the second outdoor heat exchanger above the freezing point temperature and below the dew point temperature, and the air flow generated by the reversing fan flows from the second outdoor heat exchanger to the first outdoor heat exchanger.

[0011] In some embodiments, the reversing fan, the first outdoor heat exchanger and the second outdoor heat exchanger are arranged side by side, and the reversing fan is not located in the middle position of the three.

[0012] In some embodiments, the reversing fan rotates clockwise to blow air and counterclockwise to suck air.

[0013] The application also provides an air conditioner comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the control method described above.

[0014] The application provides a control method of an air conditioning system and an air conditioner. When defrosting of a first outdoor heat exchanger is needed, a second electronic expansion valve and a second outdoor heat exchanger are controlled to keep the working state during original heating, the opening degree of a first electronic expansion valve is controlled to realize control of the evaporation temperature of refrigerant in the first outdoor heat exchanger, the temperature of the outer surface of the first outdoor heat exchanger is above the freezing point, and thus the frost on the first outdoor heat exchanger is removed. When defrosting of the second outdoor heat exchanger is needed, the first electronic expansion valve and the first outdoor heat exchanger are controlled to keep the working state during original heating, the opening degree of the second electronic expansion valve is controlled to realize control of the evaporation temperature of refrigerant in the second outdoor heat exchanger, the temperature of the outer surface of the second outdoor heat exchanger is above the freezing point, and thus the frost on the second outdoor heat exchanger is removed. During the whole defrosting process, one outdoor heat exchanger is in normal heating and the other outdoor heat exchanger is in defrosting, and the outdoor heat exchanger in defrosting is also in heating of the air conditioning system, so the indoor environment temperature does not fluctuate and thus the comfort of people is not affected. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 FIG. 1 is a structural schematic diagram of an air conditioning system according to an embodiment of the application;

[0016] Figure 2 FIG. 2 is a whole flow chart of a control method of the air conditioning system according to the embodiment of the application;

[0017] Figure 3 FIG. 3 is a specific flow chart of the control method of the air conditioning system according to the embodiment of the application.

[0018] The reference signs are as follows:

[0019] 1, first outdoor heat exchanger; 2, second outdoor heat exchanger; 3, first electronic expansion valve; 4, second electronic expansion valve; 5, reversing fan; 6, compressor; 7, indoor heat exchanger. DETAILED DESCRIPTION

[0020] For reference Figure 1 and Figure 2As shown, according to the embodiment of the present application, a control method of an air conditioning system is provided for controlling the operation of the air conditioning system, the air conditioning system comprising a first outdoor heat exchanger 1, a second outdoor heat exchanger 2, a first electronic expansion valve 3 and a second electronic expansion valve 4, the first electronic expansion valve 3 and the first outdoor heat exchanger 1 forming a first flow path, the second electronic expansion valve 4 and the second outdoor heat exchanger 2 forming a second flow path, the first flow path and the second flow path being arranged in parallel, the control method comprising: the air conditioning system operating in a heating mode, when the first outdoor heat exchanger 1 reaches a defrosting condition, controlling the opening degree of the first electronic expansion valve 3 to make the outer surface temperature of the first outdoor heat exchanger 1 reach above the freezing point temperature, and controlling the second electronic expansion valve 4 and the second outdoor heat exchanger 2 to remain in the working state in the heating mode; or when the second outdoor heat exchanger 2 reaches a defrosting condition, controlling the opening degree of the second electronic expansion valve 4 to make the outer surface temperature of the second outdoor heat exchanger 2 reach above the freezing point temperature, and controlling the first electronic expansion valve 3 and the first outdoor heat exchanger 1 to remain in the working state in the heating mode. In this technical solution, when defrosting of the first outdoor heat exchanger 1 is needed, the second electronic expansion valve 4 and the second outdoor heat exchanger 2 are controlled to remain in the working state in the original heating mode, the opening degree of the first electronic expansion valve 3 is controlled to realize control of the evaporation temperature of the refrigerant in the first outdoor heat exchanger 1, so that the outer surface temperature of the first outdoor heat exchanger 1 reaches above the freezing point temperature, thereby eliminating the frost on the first outdoor heat exchanger 1; when defrosting of the second outdoor heat exchanger 2 is needed, the first electronic expansion valve 3 and the first outdoor heat exchanger 1 are controlled to remain in the working state in the original heating mode, the opening degree of the second electronic expansion valve 4 is controlled to realize control of the evaporation temperature of the refrigerant in the second outdoor heat exchanger 2, so that the outer surface temperature of the second outdoor heat exchanger 2 reaches above the freezing point temperature, thereby eliminating the frost on the second outdoor heat exchanger 2. In the entire defrosting process, one outdoor heat exchanger is always in normal heating, and the other outdoor heat exchanger is in defrosting, and the outdoor heat exchanger in defrosting is also in defrosting while participating in heating of the air conditioning system, so the indoor environment temperature basically does not fluctuate, and therefore the comfort of people is not affected. The relationship between the increase or decrease of the opening degree of the electronic expansion valve and the rise or fall of the outer surface temperature of the corresponding outdoor heat exchanger is: when the opening degree of the electronic expansion valve increases, the outer surface temperature of the corresponding outdoor heat exchanger rises; when the opening degree of the electronic expansion valve decreases, the surface temperature of the corresponding outdoor heat exchanger decreases.

[0021] For reference Figure 1As shown, when the air conditioning system is heating at low temperature working condition, the high temperature and high pressure refrigerant from the compressor 6 is condensed and released heat to become supercooled liquid refrigerant through the indoor heat exchanger 7, the supercooled liquid refrigerant is divided into two streams, the two streams of refrigerant are throttled and decompressed to become gas-liquid mixture with different evaporation pressures through the first electronic expansion valve 3 and the second electronic expansion valve 4 respectively, then heat exchange is carried out in the first outdoor heat exchanger 1 and the second outdoor heat exchanger 2 respectively, and the low temperature and low pressure superheated steam is formed after evaporation and heat absorption, and then the low temperature and low pressure superheated steam returns to the suction pipe of the compressor 6, and then the compression cycle is carried out, and the cycle is completed through the exhaust pipe. Among them, the compressor 6 is a double-roller compressor, which has two cylinders, and the two cylinders are respectively connected with the first flow path and the second flow path, so that the compression efficiency of the refrigerant can be improved. At the same time, the air conditioning system is also provided with a four-way valve, so the air conditioning system also has a refrigeration function

[0022] Specifically, when the air conditioning system starts the heating mode, the opening degree of the first electronic expansion valve 3 is controlled to make the outer surface temperature of the first outdoor heat exchanger 1 below the freezing point temperature, and the opening degree of the second electronic expansion valve 4 is controlled to make the outer surface temperature of the second outdoor heat exchanger 2 above the freezing point temperature. When the air conditioning system is running in the heating mode and has not reached the defrosting condition, because the outer surface temperature of the first outdoor heat exchanger 1 is controlled below the freezing point temperature, and the outer surface temperature of the second outdoor heat exchanger 2 is controlled above the freezing point temperature, the first outdoor heat exchanger 1 will frost, and the outer surface of the second outdoor heat exchanger 2 will not frost. When the frost of the first outdoor heat exchanger 1 is relatively serious and the first outdoor heat exchanger 1 needs to be defrosted, the opening degree of the first electronic expansion valve 3 is controlled to make the outer surface temperature of the first outdoor heat exchanger 1 above the freezing point temperature, and the opening degree of the second electronic expansion valve 4 is controlled to make the outer surface temperature of the second outdoor heat exchanger 2 below the freezing point temperature, then the first outdoor heat exchanger 1 is switched to the state of the second outdoor heat exchanger 2 before defrosting while defrosting, and the second outdoor heat exchanger 2 is switched to the state of the first outdoor heat exchanger 1 before defrosting, so that the heating capacity of the air conditioning system does not change too much while the first outdoor heat exchanger 1 is defrosted, and the indoor environment temperature basically does not fluctuate, so as not to affect the comfort of people. Further, when the first outdoor heat exchanger 1 is defrosted, the temperature of the outer surface of the second outdoor heat exchanger 2 is below the freezing point temperature only under the adjustment of the opening degree of the second electronic expansion valve 4, and the defrosting of the first outdoor heat exchanger 1 only takes about four or five minutes, so the second outdoor heat exchanger 2 will not appear relatively serious frost in a short time during the whole defrosting process of the first outdoor heat exchanger 1, and therefore the system will not trigger the defrosting of the second outdoor heat exchanger 2 when the first outdoor heat exchanger 1 is defrosted, that is, the defrosting of the first outdoor heat exchanger 1 and the second outdoor heat exchanger 2 will not be carried out at the same time.

[0023] Specifically, when the air conditioning system starts the heating mode, the opening of the second electronic expansion valve 4 is controlled to make the outer surface temperature of the second outdoor heat exchanger 2 below the freezing point, and the opening of the first electronic expansion valve 3 is controlled to make the outer surface temperature of the first outdoor heat exchanger 1 above the freezing point. When the air conditioning system runs in the heating mode and the defrosting condition is not reached, because the outer surface temperature of the second outdoor heat exchanger 2 is controlled below the freezing point and the outer surface temperature of the first outdoor heat exchanger 1 is controlled above the freezing point, the second outdoor heat exchanger 2 will frost, while the outer surface of the first outdoor heat exchanger 1 will not frost. When the frost on the second outdoor heat exchanger 2 is serious and the second outdoor heat exchanger 2 needs to be defrosted, the opening of the second electronic expansion valve 4 is controlled to make the outer surface temperature of the second outdoor heat exchanger 2 above the freezing point, and the opening of the first electronic expansion valve 3 is controlled to make the outer surface temperature of the first outdoor heat exchanger 1 below the freezing point, so that the second outdoor heat exchanger 2 is switched to the state of the first outdoor heat exchanger 1 before defrosting at the same time of defrosting, and the first outdoor heat exchanger 1 is switched to the state of the second outdoor heat exchanger 2 before defrosting. Therefore, while achieving the defrosting of the second outdoor heat exchanger 2, the heating capacity of the air conditioning system does not change too much, so the indoor environment temperature basically does not fluctuate, thereby not affecting people's comfort. Further, when the second outdoor heat exchanger 2 is defrosted, the outer surface temperature of the first outdoor heat exchanger 1 is below the freezing point only under the adjustment of the opening of the first electronic expansion valve 3, and the defrosting of the second outdoor heat exchanger 2 only takes about four or five minutes, so during the entire defrosting process of the second outdoor heat exchanger 2, the first outdoor heat exchanger 1 will not have serious frost in a short time, so when the second outdoor heat exchanger 2 is defrosted, the system will not trigger the defrosting of the first outdoor heat exchanger 1, that is, the defrosting of the first outdoor heat exchanger 1 and the second outdoor heat exchanger 2 will not be performed at the same time

[0024] In the embodiment, the defrosting condition includes: the outside temperature Th < Ta, the difference between the temperature Tm1 at the first position of the outer surface of the first outdoor heat exchanger 1 and the temperature T2 at the air inlet of the first outdoor heat exchanger 1 is ΔT1, ΔT1 > Ts, the difference between the temperature Tm2 at the second position of the outer surface of the second outdoor heat exchanger 2 and the temperature T4 at the air inlet of the second outdoor heat exchanger 2 is ΔT2, ΔT2 > Ts, wherein Ta is a first preset value, Ts is a second preset value. The first preset value Ta is a preset value for determining whether the outside air temperature is low, 5℃ < Ta < 15℃, and the second preset value Ts is a preset value for determining whether the first outdoor heat exchanger 1 or the second outdoor heat exchanger 2 is seriously frosted when the outside temperature is low, 15℃ < Ts < 25℃. The first position is the outer surface of the middle part of the first outdoor heat exchanger 1, and the second position is the outer surface of the middle part of the second outdoor heat exchanger 2. When the outside temperature Th is less than Ta and ΔT1 is greater than Ts at the same time, it indicates that the outer surface of the first outdoor heat exchanger 1 is seriously frosted, and the first outdoor heat exchanger 1 needs to be defrosted. When the outside temperature Th is less than Ta and ΔT2 is greater than Ts at the same time, it indicates that the outer surface of the second outdoor heat exchanger 2 is seriously frosted, and the second outdoor heat exchanger 2 needs to be defrosted.

[0025] As a specific embodiment, the defrosting condition further includes: the duration Δt1 of ΔT1 > Ts exceeds a preset time ts, or the duration Δt2 of ΔT2 > Ts exceeds the preset time ts. The preset time ts is a time preset value for determining whether to defrost, 15 seconds < Ts < 30 seconds. In order to prevent defrosting misjudgment, for example, although the outside temperature Th is less than Ta and ΔT1 is greater than Ts at a certain moment, or the outside temperature Th is less than Ta and ΔT2 is greater than Ts, there may be no frost or very little frost, therefore, when the defrosting condition is reached, the time for which the defrosting condition lasts also needs to exceed the preset time ts, so as to determine that the outdoor heat exchanger is seriously frosted and needs to be defrosted. At the same time, the establishment of this condition can also avoid frequent start of the defrosting program.

[0026] In some embodiments, the air conditioning system further comprises a reversing fan 5, when defrosting the first outdoor heat exchanger 1, the opening of the first electronic expansion valve 3 is controlled to make the temperature of the outer surface of the first outdoor heat exchanger 1 above the freezing point temperature and below the dew point temperature, and the direction of the air flow generated by the reversing fan 5 is controlled to flow from the first outdoor heat exchanger 1 to the second outdoor heat exchanger 2. The addition of the reversing fan 5 has the function of delaying the frosting of the outdoor heat exchanger, when defrosting the first outdoor heat exchanger 1, the direction of the air flow generated by the reversing fan 5 is controlled to flow from the first outdoor heat exchanger 1 to the second outdoor heat exchanger 2, and the air flow passes through the first outdoor heat exchanger 1 and the second outdoor heat exchanger 2 in turn, and the opening of the first electronic expansion valve 3 is controlled to make the temperature of the outer surface of the first outdoor heat exchanger 1 between the freezing point temperature and the dew point temperature, which can dehumidify the air flowing to the first outdoor heat exchanger 1 under the condition of ensuring defrosting, that is, the moisture content in the air can be reduced, so that the air after passing through the first outdoor heat exchanger 1 becomes dry, and the dry air flow can slow down the frosting of the second outdoor heat exchanger 2 when passing through the second outdoor heat exchanger 2.

[0027] Specifically, when defrosting the second outdoor heat exchanger 2, the opening of the second electronic expansion valve 4 is controlled to make the temperature of the outer surface of the second outdoor heat exchanger 2 above the freezing point temperature and below the dew point temperature, and the direction of the air flow generated by the reversing fan 5 is controlled to flow from the second outdoor heat exchanger 2 to the first outdoor heat exchanger 1. When defrosting the second outdoor heat exchanger 2, the direction of the air flow generated by the reversing fan 5 is controlled to flow from the second outdoor heat exchanger 2 to the first outdoor heat exchanger 1, and the air flow passes through the second outdoor heat exchanger 2 and the first outdoor heat exchanger 1 in turn, and the opening of the second electronic expansion valve 4 is controlled to make the temperature of the outer surface of the second outdoor heat exchanger 2 between the freezing point temperature and the dew point temperature, so that the air flow can be dehumidified when passing through the second outdoor heat exchanger 2, and the dehumidified air flow can slow down the frosting of the first outdoor heat exchanger 1 when passing through the first outdoor heat exchanger 1.

[0028] For reference Figure 2 As shown in the figure, the detection system detects various related parameters during operation, that is, the controller of the air conditioning system obtains the outside temperature Th, the temperature T2 at the air inlet of the first outdoor heat exchanger 1, the temperature Tm1 at the first position of the outer surface of the first outdoor heat exchanger 1, the duration of the defrosting condition Δt1, the temperature T4 at the air inlet of the second outdoor heat exchanger 2, the temperature Tm2 at the second position of the outer surface of the second outdoor heat exchanger 2, and the duration of the defrosting condition Δt2. The detection data is compared with the preset values to determine whether the switching condition is met. When the preset condition is met, the control system switches the mode, that is, when the obtained data and the preset values are compared to meet the defrosting condition, the first outdoor heat exchanger 1 or the second outdoor heat exchanger 2 needs to be defrosted.

[0029] For referenceFigure 3 As shown in the figure, the first throttling valve is the first electronic expansion valve 3 of the present application, the second throttling valve is the second electronic expansion valve 4 of the present application, and the fan is the reversing fan 5 of the present application. Start-up operation: the fan runs clockwise, the first throttling valve controls the temperature of the surface of the first heat exchanger to be above the freezing point and below the dew point, and the second throttling valve controls the evaporation pressure in the second heat exchanger, thereby ensuring the normal operation of the system; that is, in the case that the air conditioning system operates in the heating mode, when defrosting the first outdoor heat exchanger 1, the reversing fan 5 is controlled to rotate clockwise, so that the airflow generated by the fan passes through the first outdoor heat exchanger 1 and the second outdoor heat exchanger 2 in turn, the opening of the first electronic expansion valve 3 is controlled to make the temperature of the outer surface of the first outdoor heat exchanger 1 reach above the freezing point and below the dew point, and the opening of the second electronic expansion valve 4 is controlled to make the temperature of the outer surface of the second outdoor heat exchanger 2 reach below the freezing point, thereby ensuring that the air conditioning system defrosts the first outdoor heat exchanger 1 in the normal heating condition. Next, under the premise that the outside air temperature Th is less than the first preset value Ta, the determination is continued, and when ΔT2> Ts and Δt2> ts are met, the mode switching is performed: the fan runs counterclockwise, the second throttling valve controls the temperature of the surface of the second heat exchanger to be above the freezing point and below the dew point, and the first throttling valve controls the evaporation pressure in the first heat exchanger, thereby ensuring the normal operation of the system; that is, when ΔT2> Ts and Δt2> ts are met, the second outdoor heat exchanger 2 is defrosted, the reversing fan 5 is controlled to rotate counterclockwise, so that the airflow generated by the fan passes through the second outdoor heat exchanger 2 and the first outdoor heat exchanger 1 in turn, the opening of the second electronic expansion valve 4 is controlled to make the temperature of the outer surface of the second outdoor heat exchanger 2 reach above the freezing point and below the dew point, and the opening of the first electronic expansion valve 3 is controlled to make the temperature of the outer surface of the first outdoor heat exchanger 1 reach below the freezing point, thereby ensuring that the air conditioning system defrosts the second outdoor heat exchanger 2 in the normal heating condition. Then, it is continuously determined whether ΔT1> Ts and Δt1> ts are met at the same time, and if so, the first outdoor heat exchanger 1 is defrosted again, thereby forming a defrosting control cycle.

[0030] In some embodiments, the reversing fan 5, the first outdoor heat exchanger 1 and the second outdoor heat exchanger 2 are arranged side by side, and the reversing fan 5 is not located in the middle position of the three, so that the airflow generated by the reversing fan 5 when working will pass through the first outdoor heat exchanger 1 and the second outdoor heat exchanger 2 in turn.

[0031] Specifically, the reversing fan 5 rotates clockwise to blow air and rotates counterclockwise to suck air. The reversing fan 5 changes the direction to realize the switching of blowing and sucking, thereby achieving the purpose of changing the direction of the airflow.

[0032] The present application also provides an air conditioner comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the control method described above.

[0033] Those skilled in the art will readily understand that the above-mentioned advantageous modes can be freely combined and superimposed without conflict.

[0034] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application. The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A control method for an air conditioning system, characterized in that, The system is used to control the operation of the air conditioning system, which includes a first outdoor heat exchanger (1), a second outdoor heat exchanger (2), a first electronic expansion valve (3), and a second electronic expansion valve (4). The first electronic expansion valve (3) and the first outdoor heat exchanger (1) form a first flow path, and the second electronic expansion valve (4) and the second outdoor heat exchanger (2) form a second flow path. The first flow path and the second flow path are connected in parallel. The control method includes: The air conditioning system operates in heating mode. When the air conditioning system starts heating mode, the opening of the first electronic expansion valve (3) is controlled to make the outer surface temperature of the first outdoor heat exchanger (1) reach below the freezing point temperature, and the opening of the second electronic expansion valve (4) is controlled to make the outer surface temperature of the second outdoor heat exchanger (2) reach above the freezing point temperature. When the first outdoor heat exchanger (1) reaches the defrosting condition, the opening of the first electronic expansion valve (3) is controlled to make the outer surface temperature of the first outdoor heat exchanger (1) reach above the freezing point temperature, and the second electronic expansion valve (4) and the second outdoor heat exchanger (2) are controlled to maintain the working state of the heating mode. Alternatively, when the air conditioning system is in heating mode, the opening of the second electronic expansion valve (4) is controlled to bring the outer surface temperature of the second outdoor heat exchanger (2) below the freezing point, and the opening of the first electronic expansion valve (3) is controlled to bring the outer surface temperature of the first outdoor heat exchanger (1) above the freezing point. When the second outdoor heat exchanger (2) reaches the defrosting condition, the opening of the second electronic expansion valve (4) is controlled to bring the outer surface temperature of the second outdoor heat exchanger (2) above the freezing point, and the first electronic expansion valve (3) and the first outdoor heat exchanger (1) are controlled to remain in the working state of the heating mode. The air conditioning system also includes a reversing fan (5), the reversing fan (5), the first outdoor heat exchanger (1) and the second outdoor heat exchanger (2) are arranged side by side, and the reversing fan (5) is not in the middle of the three; when defrosting the first outdoor heat exchanger (1), the opening of the first electronic expansion valve (3) is controlled so that the outer surface temperature of the first outdoor heat exchanger (1) reaches above the freezing point temperature and below the dew point temperature, and the airflow generated by the reversing fan (5) is controlled to flow from the first outdoor heat exchanger (1) to the second outdoor heat exchanger (2); when defrosting the second outdoor heat exchanger (2), the opening of the second electronic expansion valve (4) is controlled so that the outer surface temperature of the second outdoor heat exchanger (2) reaches above the freezing point temperature and below the dew point temperature, and the airflow generated by the reversing fan (5) is controlled to flow from the second outdoor heat exchanger (2) to the first outdoor heat exchanger (1).

2. The control method according to claim 1, characterized in that, The defrosting conditions include: the outside temperature Th < Ta, the temperature difference between the first position of the outer surface of the first outdoor heat exchanger (1) and the temperature T2 at the air inlet of the first outdoor heat exchanger (1) is ρT1, ρT1 > Ts, the temperature difference between the second position of the outer surface of the second outdoor heat exchanger (2) and the temperature T4 at the air inlet of the second outdoor heat exchanger (2) is ρT2, ρT2 > Ts, where Ta is the first preset value and Ts is the second preset value.

3. The control method according to claim 2, characterized in that, The defrosting conditions also include: the duration ρt1 of ρT1 > Ts exceeds a preset duration ts, or the duration ρt2 of ρT2 > Ts exceeds a preset duration ts.

4. The control method according to claim 1, characterized in that, The reversing fan (5) rotates clockwise to blow air and counterclockwise to draw air.

5. An air conditioner, characterized in that, It includes a processor, a memory, and a computer program stored in the memory that can run on the processor, wherein the processor executes the program to implement the steps of any one of claims 1-4.

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