Air conditioner low-temperature refrigeration control method, air conditioner and computer readable storage medium

Abstract

The invention provides an air conditioner low-temperature refrigeration control method, an air conditioner and a computer readable storage medium. The air conditioner low-temperature refrigeration control method comprises the steps that the operation rotating speed of an outdoor fan is controlled to run at the preset minimum rotating speed or the outdoor fan is controlled to stop running; the inlet temperature of the indoor heat exchanger is smaller than 0 DEG C or the cooling refrigerant temperature of an indoor controller for cooling through a refrigerant is smaller than the indoor dew point temperature or not is judged, and if yes, the air conditioner is controlled to execute failure prevention operation; the anti-failure operation comprises at least one operation of adjusting the running frequency of a compressor, adjusting the opening degree of an electronic expansion valve and adjusting the running rotating speed of an indoor fan, so that better low-temperature refrigeration running parameters of the air conditioner are dynamically sought; the failure risk of low-temperature refrigeration of the air conditioner caused by the frosting and freezing phenomena of an indoor heat exchanger or the condensation phenomenon of an indoor controller using a refrigerant for heat dissipation is avoided, so that the stability and the reliability of refrigeration operation of the air conditioner in a low-temperature environment are improved.

Description

Technical Field

[0001] This invention relates to the field of intelligent control methods for air conditioners, and in particular to a low-temperature cooling control method for an air conditioner, an air conditioner implementing the control method, and a computer-readable storage medium. Background Technology

[0002] In special locations such as data centers and communication base stations, even in winter, the indoor temperature remains high due to the continuous heat dissipation from the operation of numerous electronic components. Therefore, the air conditioners used in these special locations must be able to operate stably in low-temperature winter environments to ensure the stable and reliable operation of the numerous electronic components in these locations, thus preventing them from overheating and being damaged due to the increased indoor temperature.

[0003] An existing type of air conditioner has an indoor unit equipped with components such as an indoor heat exchanger and an indoor fan, and an outdoor unit equipped with components such as an outdoor heat exchanger, an outdoor fan, and a compressor. Placing the compressor in the outdoor unit can avoid the noise generated by the compressor operation from interfering with the indoor environment, and can also reduce the space size of the indoor unit. However, when this air conditioner is running in low-temperature cooling mode (usually when the outdoor temperature is below 0°C), because the refrigerant supplied from the outdoor heat exchanger to the indoor unit is directly supplied to the indoor heat exchanger, the inlet temperature of the indoor heat exchanger (evaporator) is easily lower than 0°C. This can easily lead to frost and ice formation on the indoor heat exchanger, resulting in a decrease in the heat exchange efficiency of the indoor heat exchanger. Consequently, the refrigerant inside the indoor heat exchanger cannot absorb heat from the surrounding air and cannot evaporate sufficiently. This insufficiently evaporated liquid refrigerant can be sucked into the compressor, causing a risk of liquid slugging.

[0004] Another type of air conditioner has an indoor unit equipped with components such as an indoor heat exchanger, an indoor fan, a compressor, and a controller, while the outdoor unit is equipped with components such as an outdoor heat exchanger and an outdoor fan. The controller in the indoor unit, which controls the entire air conditioner, uses refrigerant for heat dissipation. The compressor is located in the indoor unit, which makes the heat exchange effect more stable and facilitates daily maintenance and repair. However, when this air conditioner is running in low-temperature cooling mode (usually when the outdoor temperature is below 0°C), the refrigerant sent to the indoor unit by the outdoor heat exchanger first dissipates heat from the controller in the indoor unit. This can easily cause the temperature of the refrigerant after passing through the controller to drop below 0°C, leading to condensation on the controller. This can cause short circuits, false triggers, signal interruptions, and other malfunctions in the controller, ultimately damaging it.

[0005] To prevent frost or ice buildup on the indoor heat exchanger or condensation on the controller that uses refrigerant for heat dissipation, existing air conditioners use a low-temperature cooling control method that involves reducing the speed of the outdoor fan or shutting it off to increase the temperature of the refrigerant entering the indoor unit.

[0006] However, in windy weather, even if existing air conditioner low-temperature cooling control methods reduce the speed of the outdoor fan or shut it off, the refrigerant flowing through the outdoor heat exchanger can still dissipate heat quickly due to the low outdoor ambient temperature and fast outdoor air circulation. This results in the refrigerant entering the indoor heat exchanger or dissipating heat for the indoor controller still having a low temperature. Consequently, the indoor heat exchanger still faces the risk of frosting or icing, and the controller that uses the refrigerant for heat dissipation still faces the risk of condensation. This affects the stability and reliability of the air conditioner's low-temperature cooling operation, and may lead to the failure of the air conditioner's low-temperature cooling function. Summary of the Invention

[0007] To achieve the first objective of this invention, this invention provides a low-temperature cooling control method for air conditioners, which can dynamically seek optimal low-temperature cooling operating parameters for air conditioners to prevent frost or ice formation on the indoor heat exchanger or condensation on the indoor controller that uses refrigerant for heat dissipation, which could lead to the risk of failure in low-temperature cooling of the air conditioner. This ensures the heat exchange performance of the air conditioner during low-temperature cooling operation while improving the stability and reliability of the air conditioner's cooling operation in low-temperature environments.

[0008] To achieve the second objective of this invention, this invention provides an air conditioner that performs the above-described air conditioner low-temperature cooling control method.

[0009] To achieve the third objective of this invention, this invention provides a computer-readable storage medium for performing the above-described air conditioner low-temperature refrigeration control method.

[0010] To achieve the first objective of this invention, this invention provides a method for controlling low-temperature cooling in an air conditioner, comprising: controlling the air conditioner to operate in a preset mode for cooling; when the outdoor ambient temperature... Less than the preset low temperature threshold When the air conditioner is determined to be in low-temperature cooling mode, the outdoor fan speed is controlled to operate at a preset minimum speed or the outdoor fan is stopped. After the outdoor fan has been operating at the preset minimum speed or stopped for a first preset time, it is determined whether the following condition is met: the inlet temperature of the indoor heat exchanger. The refrigerant temperature of the indoor controller that dissipates heat at temperatures below 0°C or using refrigerant for heat dissipation. Less than the indoor dew point temperature If so, the air conditioner is controlled to perform a fail-safe operation; the fail-safe operation includes at least one of the following: adjusting the operating frequency of the compressor, adjusting the opening of the electronic expansion valve, and adjusting the operating speed of the indoor fan.

[0011] A further solution is that the failure prevention operation includes: controlling the compressor's operating frequency to decrease from a first preset frequency to a first frequency. Running; when the compressor operates at the first frequency After running for the second preset duration, the first temperature difference is calculated and obtained. Then when the compressor operates at the first frequency After running for the third preset duration, the second temperature difference is calculated and obtained. Determine if the condition is met. and If so, the compressor's operating frequency will be restored to the preset operating mode frequency; where, For the compressor at the first frequency The inlet temperature of the indoor heat exchanger after running for the second preset time. For the compressor at the first frequency The inlet temperature of the indoor heat exchanger before the second preset running time. For the compressor at the first frequency The inlet temperature of the indoor heat exchanger after running for the third preset time. For the compressor at the first frequency The inlet temperature of the indoor heat exchanger before the third preset running time. This is the first predetermined temperature difference.

[0012] A further option is to, when it is determined that the conditions are not met... and If the condition is met, then determine whether the condition is satisfied: the inlet temperature of the indoor heat exchanger. The refrigerant temperature of the indoor controller that dissipates heat at temperatures below 0°C or using refrigerant for heat dissipation. Less than the indoor dew point temperature If so, the operating frequency of the compressor will be controlled to continue decreasing from the first preset frequency to the first frequency. Run; otherwise, maintain the compressor's operating frequency at the current first frequency. run.

[0013] A further solution is that the failure prevention operation also includes: when the operating frequency of the control compressor returns to the preset operating mode frequency, the operating frequency of the control compressor is increased to a second preset frequency. Running; when the compressor operates at the second frequency After running for the fourth preset duration, the third temperature difference is calculated and obtained. Then when the compressor operates at the second frequency After running for the fifth preset duration, the fourth temperature difference is calculated and obtained. Determine if the condition is met. and If so, the compressor's operating frequency will be restored to the preset operating mode frequency; where, For the compressor at the second frequency The inlet temperature of the indoor heat exchanger after running for the fourth preset time. For the compressor at the second frequency The inlet temperature of the indoor heat exchanger before the fourth preset running time. For the compressor at the second frequency The inlet temperature of the indoor heat exchanger after running for the fifth preset time. For the compressor at the second frequency The inlet temperature of the indoor heat exchanger before the fifth preset running time. This is the second predetermined temperature difference.

[0014] A further option is to, when it is determined that the conditions are not met... and If the condition is met, then determine whether the condition is satisfied: the inlet temperature of the indoor heat exchanger. The refrigerant temperature of the indoor controller that dissipates heat at temperatures below 0°C or using refrigerant for heat dissipation. Less than the indoor dew point temperature If so, the operating frequency of the compressor will be increased to the second preset frequency. Run; otherwise, maintain the compressor's operating frequency at the current second frequency. run.

[0015] A further solution is that the failure prevention operation also includes: when the operating frequency of the control compressor returns to the operating frequency of the preset operating mode, the opening of the control electronic expansion valve is increased to the first flow opening by a first preset number of steps; after the electronic expansion valve operates at the first flow opening for a sixth preset time, it is determined whether the following conditions are met. If so, the operating speed of the indoor fan will be increased by a preset speed; after the indoor fan has been running at the preset speed for a seventh preset time, it will be determined whether the condition is met. If so, then check again whether the condition is met. If not, the opening of the electronic expansion valve is reduced to the second flow opening by the second preset number of steps, and the condition is checked again to see if the requirement is met. The second preset number of steps is less than the first preset number of steps. The value of the compressor's phase current fluctuation after the electronic expansion valve has been running at its first opening for a preset period of time. This is the compressor's preset liquid slugging constant. The value of the compressor's phase current fluctuation after the indoor fan's operating speed is increased by a preset speed for a seventh preset time. The operating speed of the indoor fan is increased by the preset speed to measure the phase current fluctuation value of the compressor before the seventh preset time period.

[0016] A further option is to, when it is determined that the conditions are not met... If so, determine whether the condition is met: the inlet temperature of the indoor heat exchanger. The refrigerant temperature of the indoor controller that dissipates heat at temperatures below 0°C or using refrigerant for heat dissipation. Less than the indoor dew point temperature If so, the opening of the electronic expansion valve is controlled to continue increasing to the first flow opening by the first preset number of steps; otherwise, the opening of the electronic expansion valve is controlled to maintain the current first flow opening or maintain the current second flow opening.

[0017] A further approach is to calculate the maximum difference in phase current of the compressor once within a preset interval. : ; Calculate the ratio Then calculate and obtain ;in, This represents the maximum phase current of the compressor within a preset interval. This is the minimum phase current of the compressor within a preset interval. This is the preset fluctuation value for when the compressor does not experience liquid slugging.

[0018] A further approach is to calculate the indoor dew point temperature based on the indoor ambient temperature and humidity. .

[0019] To achieve the second objective of this invention, this invention provides an air conditioner, including an indoor unit and an outdoor unit with circuit boards. The circuit boards are provided with a processor and a memory. The memory stores a computer program. When the computer program is executed by the processor, it implements the various steps of the above-described air conditioner low-temperature cooling control method.

[0020] To achieve the third objective of this invention, a computer-readable storage medium is provided, on which a computer program is stored, which, when executed by a processor, implements the various steps of the above-described air conditioner low-temperature refrigeration control method.

[0021] Therefore, the air conditioner low-temperature cooling control method of the present invention controls the air conditioner to perform anti-failure operations, namely, adjusting the operating frequency of the compressor, adjusting the opening of the electronic expansion valve, and adjusting the operating speed of the indoor fan. This dynamically seeks the optimal low-temperature cooling operating parameters of the air conditioner, thereby preventing the air conditioner from failing due to frost or ice formation on the indoor heat exchanger or condensation on the indoor controller that uses refrigerant for heat dissipation. This ensures the heat exchange performance of the air conditioner during low-temperature cooling operation while improving the stability and reliability of the air conditioner's cooling operation in low-temperature environments. Attached Figure Description

[0022] Figure 1 This is a control flowchart of an embodiment of the air conditioner low-temperature cooling control method of the present invention.

[0023] Figure 2 This is a flowchart illustrating the compressor frequency reduction during the failure prevention operation in an embodiment of the air conditioner low-temperature refrigeration control method of the present invention.

[0024] Figure 3 This is a flowchart illustrating the compressor frequency increase during the failure prevention operation in an embodiment of the air conditioner low-temperature refrigeration control method of the present invention.

[0025] Figure 4 This is a flowchart illustrating the increase in the opening degree of the electronic expansion valve during the failure prevention operation in an embodiment of the air conditioner low-temperature refrigeration control method of the present invention.

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0027] Various exemplary embodiments of the invention will now be described in detail with reference to the accompanying drawings. The descriptions of the exemplary embodiments are merely illustrative and are in no way intended to limit the invention or its application or use. The invention can be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the invention thorough and complete, and to fully express the scope of the invention to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, the composition of materials, numerical expressions, and values ​​set forth in these embodiments should be interpreted as merely exemplary and not as limiting.

[0028] The terms "first," "second," and similar words used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. Words such as "including" or "comprising" mean that the element preceding the word encompasses the element listed after it, without excluding the possibility of encompassing other elements. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0029] In this invention, when a specific device is described as being located between a first device and a second device, an intermediary device may or may not be present between the specific device and the first or second device. When a specific device is described as being connected to other devices, the specific device may be directly connected to the other devices without an intermediary device, or it may not be directly connected to the other devices but may have an intermediary device.

[0030] All terms used in this invention (including technical or scientific terms) have the same meaning as understood by one of ordinary skill in the art, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having the meaning consistent with their meaning in the context of the relevant art, and not as having an idealized or highly formalized meaning, unless expressly defined herein.

[0031] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0032] Example of a method for controlling low-temperature cooling in an air conditioner: This embodiment of the low-temperature cooling control method for air conditioners is applicable to two types of air conditioners. Conventional air conditioner models have indoor units equipped with indoor heat exchangers, indoor fans, and other components, while their outdoor units have outdoor heat exchangers, outdoor fans, compressors, and other components. Placing the compressor in the outdoor unit avoids noise interference with the indoor environment and reduces the size of the indoor unit. In conventional air conditioner models, the refrigerant supplied from the outdoor heat exchanger to the indoor unit is directly supplied to the indoor heat exchanger. Specialized air conditioner models have indoor units equipped with indoor heat exchangers, indoor fans, compressors, controllers, and other components, while the outdoor unit has outdoor heat exchangers, outdoor fans, and other components. The controller in the indoor unit, which controls the entire air conditioner, uses refrigerant for heat dissipation. Placing the compressor in the indoor unit makes the heat exchange effect more stable and facilitates routine maintenance. In specialized air conditioner models, the refrigerant supplied from the outdoor heat exchanger to the indoor unit first dissipates heat from the indoor unit's controller.

[0033] See Figure 1 The following is a control flowchart of the low-temperature cooling control method for the air conditioner in this embodiment. The specific steps are as follows.

[0034] Execute step S11 to control the air conditioner to run in a preset operating mode for cooling. That is, the user sends a message to the indoor unit of the air conditioner via remote control to control the outdoor unit to run in the preset operating mode for cooling, so that the air conditioner runs in the user's preset operating mode for cooling.

[0035] Next, proceed to step S12 to determine the outdoor ambient temperature. Is it less than the preset low temperature threshold? Specifically, the outdoor unit of the air conditioner is equipped with a first temperature sensor, which detects the outdoor ambient temperature in real time. For example, a preset low temperature threshold. The temperature range is 0~5℃, preferably with a preset low temperature threshold. The temperature is 3℃.

[0036] When step S12 determines that the condition is satisfied At that time, i.e., outdoor ambient temperature Less than the preset low temperature threshold Therefore, the outdoor ambient temperature If the temperature is below 3°C, proceed to step S13 to determine that the air conditioner is in a low-temperature cooling state.

[0037] When step S12 is determined not to be satisfied At that time, i.e., outdoor ambient temperature Equal to or greater than the preset low temperature threshold Therefore, the outdoor ambient temperature If the temperature is equal to or greater than 3°C, return to step S11, and the air conditioner will continue to operate in the preset cooling mode.

[0038] When step S13 determines that the air conditioner is in a low-temperature cooling state, it indicates that the indoor heat exchanger of the air conditioner is prone to frost or ice formation, or that the indoor controller that uses refrigerant for heat dissipation is prone to condensation, which may lead to a risk of failure in the low-temperature cooling of the air conditioner. Therefore, step S14 is executed to control the operating speed of the outdoor fan to operate at a preset minimum speed or to control the outdoor fan to stop operating, so as to reduce the heat exchange effect of the outdoor heat exchanger (condenser), thereby increasing the outlet temperature of the outdoor heat exchanger, and thus increasing the temperature of the refrigerant supplied to the indoor unit, so as to avoid frost or ice formation on the indoor heat exchanger or condensation on the indoor controller that uses refrigerant for heat dissipation, which may lead to a risk of failure in the low-temperature cooling of the air conditioner.

[0039] Due to severe weather conditions such as strong winds and heavy rain, the outdoor heat exchanger (condenser) cannot be weakened when the outdoor fan is running at the preset minimum speed or is stopped. This makes it difficult to increase the outlet temperature of the outdoor heat exchanger, and it is difficult to avoid frost or ice formation on the indoor heat exchanger or condensation on the indoor controller that uses refrigerant for heat dissipation. Therefore, the operation of controlling the outdoor fan to run at the preset minimum speed or stopping the outdoor fan in step S14 may fail to prevent the air conditioner from failing at low temperature. As a result, the air conditioner still has the risk of failing at low temperature. Therefore, step S15 is then executed to control the outdoor fan to run at the preset minimum speed or stop the outdoor fan for a first preset time, for example, the first preset time is 5 minutes.

[0040] If the outdoor fan operates at the preset minimum speed or stops running for 5 minutes after step S15, then proceed to step S16 to determine whether the condition is met: the inlet temperature of the indoor heat exchanger. The refrigerant temperature of the indoor controller that dissipates heat at temperatures below 0°C or using refrigerant for heat dissipation. Less than the indoor dew point temperature If yes, proceed to step S17; otherwise, proceed to step S14.

[0041] When step S16 determines that the condition is met: or When the low-temperature cooling control method of this embodiment is applied to a conventional air conditioner model, the following condition is determined to be met: This indicates the inlet temperature of the indoor heat exchanger. If the temperature is below 0°C, there is a risk of frost or ice formation on the indoor heat exchanger (evaporator). When the low-temperature cooling control method of this embodiment is applied to a specially designed air conditioner model, the following conditions are determined to be met: This indicates the refrigerant temperature of the indoor controller that uses refrigerant for heat dissipation. Less than the indoor dew point temperature If the indoor controller that uses refrigerant for heat dissipation is at risk of condensation, then step S17 is executed to control the air conditioner to perform a failure prevention operation. Specifically, in this embodiment, the failure prevention operation includes at least one of the following operations: adjusting the operating frequency of the compressor, adjusting the opening of the electronic expansion valve, and adjusting the operating speed of the indoor fan. This is to further prevent the indoor heat exchanger from frosting or icing, or the indoor controller that uses refrigerant for heat dissipation from condensing, which could lead to a failure of the air conditioner in low-temperature cooling. This eliminates the possibility of the air conditioner failing in low-temperature cooling due to frosting or icing of the indoor heat exchanger or condensation of the indoor controller that uses refrigerant for heat dissipation. While ensuring the heat exchange performance of the air conditioner in low-temperature cooling operation, the stability and reliability of the air conditioner in low-temperature environments are improved.

[0042] When step S16 determines that the condition is not met: or When the low-temperature cooling control method of this embodiment is applied to a conventional air conditioner model, it is determined that the condition is not met: This indicates the inlet temperature of the indoor heat exchanger. If the temperature is equal to or greater than 0°C, there is no risk of frost or ice formation on the indoor heat exchanger (evaporator). However, when the low-temperature cooling control method of this embodiment is applied to a specially designed air conditioner model, the condition is determined not to be met. This indicates the refrigerant temperature of the indoor controller that uses refrigerant for heat dissipation. Equal to or greater than the indoor dew point temperature If the indoor controller that uses refrigerant for heat dissipation does not have the risk of condensation, and the current operating parameters of the air conditioner can meet the stability and reliability of the air conditioner's cooling operation in low-temperature environments, then step S14 is executed to continue controlling the outdoor fan's operating speed to run at the preset minimum speed, or to continue controlling the outdoor fan to stop running, in order to improve the stability and reliability of the air conditioner's cooling operation in low-temperature environments.

[0043] Specifically, a second temperature sensor is installed at the inlet of the indoor heat exchanger of the air conditioner, and the second temperature sensor detects the inlet temperature of the indoor heat exchanger in real time. In fact, the inlet temperature of the indoor heat exchanger It can display the temperature of the refrigerant entering the indoor heat exchanger (evaporator). In addition, specially designed air conditioner models have a third temperature sensor installed at the indoor controller, which monitors the temperature of the refrigerant dissipating heat from the indoor controller in real time. .

[0044] Furthermore, the indoor dew point temperature is calculated based on the indoor ambient temperature and humidity. The indoor unit of the air conditioner is equipped with a fourth temperature sensor and a humidity sensor. The fourth temperature sensor detects the indoor ambient temperature in real time, and the humidity sensor detects the indoor ambient humidity in real time. Preferably, the low-temperature cooling control method of this embodiment uses the Magnus formula to calculate the indoor dew point temperature based on the indoor ambient temperature and humidity. .

[0045] See Figure 2 The flowchart below shows the compressor frequency reduction process during the failure prevention operation in the low-temperature cooling control method of the air conditioner in this embodiment. The specific steps are as follows.

[0046] After step S17 controls the air conditioner to perform the fail-safe operation, step S71 is executed to control the compressor's operating frequency to decrease from the first preset frequency to the first frequency. Run, then execute step S72, the compressor operates at the first frequency Run for the second preset duration.

[0047] When step S72, the compressor operates at the first frequency after frequency reduction. After running for the second preset duration, step S73 is executed to calculate and obtain the first temperature difference. .in, For the compressor at the first frequency The inlet temperature of the indoor heat exchanger after running for the second preset time. For the compressor at the first frequency The inlet temperature of the indoor heat exchanger before the second preset running time.

[0048] Next, step S74 is executed, controlling the compressor to operate at the first frequency after frequency reduction. After running for the third preset time, step S75 is executed to calculate and obtain the second temperature difference. .in, For the compressor at the first frequency The inlet temperature of the indoor heat exchanger after running for the third preset time. For the compressor at the first frequency The inlet temperature of the indoor heat exchanger before the third preset running time.

[0049] and, This is the first predetermined temperature difference.

[0050] Then, step S76 is executed to determine whether the condition is met. and If so, proceed to step S79; otherwise, proceed to step S77.

[0051] For example, the first preset frequency is 2Hz, the second preset duration is 5min, the third preset duration is 3min, and the first preset temperature difference... The temperature is 0℃. Therefore, after step S17 controls the air conditioner to perform the fail-safe operation, step S71 controls the compressor's operating frequency to decrease to the first frequency at 2Hz. During operation, step S72 involves the compressor operating at the first frequency after frequency reduction. After running for 5 minutes, step S73 calculates and obtains the first temperature difference. That is, to obtain the compressor at the first frequency The inlet temperature of the indoor heat exchanger after running for 5 minutes With the compressor at the first frequency The inlet temperature of the indoor heat exchanger 5 minutes before operation The difference between them, then step S74 controls the compressor to operate at the first frequency after frequency reduction. After running for 3 minutes, step S75 calculates and obtains the second temperature difference. That is, to obtain the compressor at the first frequency The inlet temperature of the indoor heat exchanger after running for 3 minutes With the compressor at the first frequency Inlet temperature of the indoor heat exchanger 3 minutes before operation The difference between them is then used to determine whether step S76 satisfies the condition. and .

[0052] When step S76 determines that the condition is not met. and When the condition is met, it is determined that the condition is not satisfied. and ,thereby and / or This indicates that the compressor's operating frequency has decreased from the first preset frequency to the first frequency. After operation, the inlet temperature of the indoor heat exchanger is higher than the compressor's operating frequency, and then decreases to a first preset frequency. The inlet temperature of the indoor heat exchanger before operation indicates that the compressor's frequency reduction operation effectively weakens the heat exchange effect of the outdoor heat exchanger (condenser), thereby increasing the outlet temperature of the outdoor heat exchanger and consequently increasing the refrigerant temperature supplied to the indoor unit. This prevents frost or ice formation on the indoor heat exchanger or condensation on the indoor controller that uses refrigerant for heat dissipation, which could lead to air conditioner failure due to low-temperature cooling. To ensure the reliability of the fail-safe operation, step S77 is executed to determine whether the condition: the inlet temperature of the indoor heat exchanger is met. The refrigerant temperature of the indoor controller that dissipates heat at temperatures below 0°C or using refrigerant for heat dissipation. Less than the indoor dew point temperature If so, proceed to step S71; otherwise, proceed to step S78.

[0053] When step S77 determines that the condition is met: or When the low-temperature cooling control method of this embodiment is applied to a conventional air conditioner model, the following condition is determined to be met: This indicates the inlet temperature of the indoor heat exchanger. If the temperature is below 0°C, there is a risk of frost or ice formation on the indoor heat exchanger (evaporator). When the low-temperature cooling control method of this embodiment is applied to a specially designed air conditioner model, the following conditions are determined to be met: This indicates the refrigerant temperature of the indoor controller that uses refrigerant for heat dissipation. Less than the indoor dew point temperature If the indoor controller that uses refrigerant for heat dissipation is at risk of condensation, then step S71 is executed, continuing to control the compressor's operating frequency to continue decreasing to the first preset frequency. The compressor is further de-frequency operated to further reduce the heat exchange effect of the outdoor heat exchanger (condenser), further increase the outlet temperature of the outdoor heat exchanger, and further increase the temperature of the refrigerant sent to the indoor unit. This effectively avoids frost or ice formation on the indoor heat exchanger or condensation on the indoor controller that uses refrigerant for heat dissipation, which could lead to the risk of air conditioner failure due to low-temperature cooling.

[0054] When step S77 determines that the condition is not met: or When the low-temperature cooling control method of this embodiment is applied to a conventional air conditioner model, it is determined that the condition is not met: This indicates the inlet temperature of the indoor heat exchanger. If the temperature is equal to or greater than 0°C, there is no risk of frost or ice formation on the indoor heat exchanger (evaporator). However, when the low-temperature cooling control method of this embodiment is applied to a specially designed air conditioner model, the condition is determined not to be met. This indicates the refrigerant temperature of the indoor controller that uses refrigerant for heat dissipation. Equal to or greater than the indoor dew point temperature If the indoor controller, which utilizes refrigerant for heat dissipation, has no risk of condensation, then the current operating parameters of the air conditioner can meet the stability and reliability requirements of its cooling operation in low-temperature environments. Therefore, step S78 is executed to maintain the compressor's operating frequency at the current first frequency. To improve the stability and reliability of the air conditioner's cooling operation in low-temperature environments.

[0055] When step S76 determines that the condition is satisfied and When the condition is met, it is determined that the condition is satisfied. and This indicates that the compressor's operating frequency has decreased from the first preset frequency to the first frequency. After operation, the inlet temperature of the indoor heat exchanger is equal to or less than the compressor's operating frequency, decreasing to a first preset frequency. If the inlet temperature of the indoor heat exchanger before operation is found to be low, it indicates that the compressor frequency reduction operation cannot effectively reduce the heat exchange effect of the outdoor heat exchanger (condenser). Instead, it increases the heat exchange effect of the outdoor heat exchanger (condenser). This means that the compressor frequency reduction operation cannot reduce the heat exchange effect of the outdoor heat exchanger (condenser) to avoid frost or ice formation on the indoor heat exchanger or condensation on the indoor controller that uses refrigerant for heat dissipation. Therefore, step S79 is executed to control the compressor's operating frequency to return to the preset operating mode's operating frequency.

[0056] See Figure 3 The flowchart below shows the compressor frequency increase process during the failure prevention operation in the low-temperature refrigeration control method of the air conditioner in this embodiment. The specific steps are as follows.

[0057] Since reducing the compressor's frequency cannot weaken the heat exchange effect of the outdoor heat exchanger (condenser) to avoid frost or ice formation on the indoor heat exchanger or condensation on the indoor controller that uses refrigerant for heat dissipation, after step S79 controls the compressor's operating frequency to return to the preset operating mode's operating frequency, step S710 is executed to control the compressor's operating frequency to increase from the second preset frequency to the second frequency. Run, then execute step S711, the compressor operates at the second frequency Run for the fourth preset duration.

[0058] When step S711, the compressor operates at the second frequency after frequency boosting. After running for the fourth preset duration, step S712 is executed to calculate and obtain the third temperature difference. .in, For the compressor at the second frequency The inlet temperature of the indoor heat exchanger after running for the fourth preset time. For the compressor at the second frequency The inlet temperature of the indoor heat exchanger before the fourth preset running time.

[0059] Next, step S713 is executed, controlling the compressor to operate at the second frequency after frequency increase. After running for the fifth preset duration, step S714 is executed to calculate and obtain the fourth temperature difference. .in, For the compressor at the second frequency The inlet temperature of the indoor heat exchanger after running for the fifth preset time. For the compressor at the second frequency The inlet temperature of the indoor heat exchanger before the fifth preset running time.

[0060] and, This is the second predetermined temperature difference.

[0061] Then, step S715 is executed to determine whether the condition is met. and If yes, proceed to step S718; otherwise, proceed to step S716.

[0062] For example, the second preset frequency is 2Hz, the fourth preset duration is 5min, the fifth preset duration is 3min, and the second preset temperature difference... The temperature is 0℃. Therefore, after step S79 controls the compressor's operating frequency to return to the preset operating mode's operating frequency, step S710 controls the compressor's operating frequency to increase to a second frequency of 2Hz. During operation, step S711 compressor operates at the second frequency after frequency boosting. After running for 5 minutes, step S712 calculates and obtains the third temperature difference. That is, to obtain the compressor at the second frequency The inlet temperature of the indoor heat exchanger after running for 5 minutes With the compressor at the second frequency The inlet temperature of the indoor heat exchanger 5 minutes before operation The difference between them, then step S713 controls the compressor to operate at the second frequency after frequency boosting. After running for 3 minutes, step S714 calculates and obtains the fourth temperature difference. That is, to obtain the compressor at the second frequency The inlet temperature of the indoor heat exchanger after running for 3 minutes With the compressor at the second frequency Inlet temperature of the indoor heat exchanger 3 minutes before operation The difference between them is then used to determine whether step S715 satisfies the condition. and .

[0063] When step S715 determines that the condition is not met. and When the condition is met, it is determined that the condition is not satisfied. and ,thereby and / or This indicates that the compressor's operating frequency increases from the second preset frequency to the second frequency. After operation, the inlet temperature of the indoor heat exchanger increases to the second preset frequency when it exceeds the compressor's operating frequency. The inlet temperature of the indoor heat exchanger before operation indicates that the compressor's frequency increase operation can effectively reduce the heat exchange effect of the outdoor heat exchanger (condenser), thereby increasing the outlet temperature of the outdoor heat exchanger and thus increasing the temperature of the refrigerant supplied to the indoor unit. This can prevent frost or ice formation on the indoor heat exchanger or condensation on the indoor controller that uses refrigerant for heat dissipation, which could lead to the risk of air conditioner failure due to low-temperature cooling. To ensure the reliability of the fail-safe operation, step S716 is executed to determine whether the condition: the inlet temperature of the indoor heat exchanger is met. The refrigerant temperature of the indoor controller that dissipates heat at temperatures below 0°C or using refrigerant for heat dissipation. Less than the indoor dew point temperature If yes, proceed to step S710; otherwise, proceed to step S717.

[0064] When step S716 determines that the condition is met: or When the low-temperature cooling control method of this embodiment is applied to a conventional air conditioner model, the following condition is determined to be met: This indicates the inlet temperature of the indoor heat exchanger. If the temperature is below 0°C, there is a risk of frost or ice formation on the indoor heat exchanger (evaporator). When the low-temperature cooling control method of this embodiment is applied to a specially designed air conditioner model, the following conditions are determined to be met: This indicates the refrigerant temperature of the indoor controller that uses refrigerant for heat dissipation. Less than the indoor dew point temperature If the indoor controller that uses refrigerant for heat dissipation is at risk of condensation, then step S710 is executed, continuing to control the compressor's operating frequency to continue increasing to the second preset frequency. The compressor is further frequency-increased during operation to further reduce the heat exchange effect of the outdoor heat exchanger (condenser), further increase the outlet temperature of the outdoor heat exchanger, and further increase the temperature of the refrigerant supplied to the indoor unit. This effectively avoids frost or ice formation on the indoor heat exchanger or condensation on the indoor controller that uses refrigerant for heat dissipation, which could lead to the risk of air conditioner failure due to low-temperature cooling.

[0065] When step S716 determines that the condition is not met: or When the low-temperature cooling control method of this embodiment is applied to a conventional air conditioner model, it is determined that the condition is not met: This indicates the inlet temperature of the indoor heat exchanger. If the temperature is equal to or greater than 0°C, there is no risk of frost or ice formation on the indoor heat exchanger (evaporator). However, when the low-temperature cooling control method of this embodiment is applied to a specially designed air conditioner model, the condition is determined not to be met. This indicates the refrigerant temperature of the indoor controller that uses refrigerant for heat dissipation. Equal to or greater than the indoor dew point temperature If the indoor controller using refrigerant for heat dissipation has no risk of condensation, then the current operating parameters of the air conditioner can meet the stability and reliability requirements of the air conditioner's cooling operation in low-temperature environments. Therefore, step S717 is executed to control the compressor's operating frequency to maintain the current second frequency. To improve the stability and reliability of the air conditioner's cooling operation in low-temperature environments.

[0066] When step S715 determines that the condition is satisfied and When the condition is met, it is determined that the condition is satisfied. and This indicates that the compressor's operating frequency increases from the second preset frequency to the second frequency. After operation, the inlet temperature of the indoor heat exchanger is equal to or less than the compressor's operating frequency, and then rises to a second preset frequency. If the inlet temperature of the indoor heat exchanger before operation is found to be low, it indicates that the compressor frequency increase operation cannot effectively reduce the heat exchange effect of the outdoor heat exchanger (condenser). Instead, it increases the heat exchange effect of the outdoor heat exchanger (condenser). This means that the compressor frequency increase operation cannot reduce the heat exchange effect of the outdoor heat exchanger (condenser) to avoid frost or ice formation on the indoor heat exchanger or condensation on the indoor controller that uses refrigerant for heat dissipation. Therefore, step S718 is executed to control the compressor's operating frequency to return to the preset operating mode's operating frequency.

[0067] See Figure 4 The flowchart below shows the process of increasing the opening of the electronic expansion valve during the failure prevention operation of the low-temperature refrigeration control method for the air conditioner in this embodiment. The specific steps are as follows.

[0068] Since the compressor frequency increase operation cannot weaken the heat exchange effect of the outdoor heat exchanger (condenser) to avoid frost or ice formation on the indoor heat exchanger or condensation on the indoor controller that uses refrigerant for heat dissipation, after step S718 controls the compressor's operating frequency to return to the preset operating mode's operating frequency, step S719 is executed to control the opening of the electronic expansion valve to increase to the first flow opening by the first preset number of steps. Then, step S720 is executed to run the electronic expansion valve at the first flow opening for the sixth preset time.

[0069] After the electronic expansion valve has operated at the increased first flow opening for a sixth preset time in step S720, step S721 is executed to determine whether the condition is met. If so, proceed to step 722; otherwise, proceed to step 726. Wherein, The value of the compressor's phase current fluctuation after the electronic expansion valve has been running at its first opening for a preset period of time. This is the preset liquid slugging constant for the compressor.

[0070] Specifically, the maximum difference in phase current of the compressor is calculated once within a preset interval. ; Therefore, the ratio is calculated. ; This allows for the calculation of the phase current fluctuation value of the compressor within the preset interval. .

[0071] in, This represents the maximum phase current of the compressor within a preset interval. This is the minimum phase current of the compressor within a preset interval. This is the preset fluctuation value for when the compressor is free from liquid slugging. Specifically, the preset interval is 5 seconds.

[0072] For example, the first preset number of steps is 10 steps, the sixth preset duration is 5 minutes, and the compressor's preset liquid slugging constant is... The value is 16. Therefore, in step S719, the opening of the electronic expansion valve is increased in 10 steps to the first flow opening. In step S720, after the electronic expansion valve operates at the increased first flow opening for 5 minutes, step S721 determines whether the following conditions are met. That is, to determine whether the condition is met. .

[0073] As the electronic expansion valve increases its opening, the inlet temperature of the indoor heat exchanger can be raised. However, due to the increased refrigerant circulation in the entire refrigeration system, the indoor heat exchanger (evaporator) may not be able to completely evaporate, resulting in liquid carryover during suction. Liquid carryover during suction may damage the compressor, leading to a risk of liquid slugging in the compressor. Therefore, when step S721 determines that the conditions are met... When, that is, it is determined that the condition is met. If the compressor is at risk of liquid slugging, step S722 is executed to increase the operating speed of the indoor fan to a preset speed. Then step S723 is executed to increase the operating speed of the indoor fan to a preset speed for a seventh preset time.

[0074] After the indoor fan's operating speed increases by a preset speed for a seventh preset time in step S723, step S724 is executed to determine whether the condition is met. If so, proceed to step S721; otherwise, proceed to step S725. Wherein, The value of the compressor's phase current fluctuation after the indoor fan's operating speed is increased by a preset speed for a seventh preset time. The operating speed of the indoor fan is increased by the preset speed to measure the phase current fluctuation value of the compressor before the seventh preset time period.

[0075] For example, the preset rotation speed is 10 rpm, and the seventh preset duration is 3 minutes. Therefore, step S721 determines that the following conditions are met. If the compressor is at risk of liquid slugging, step S722 is executed, increasing the indoor fan speed by 10 rpm. Increasing the indoor fan speed increases the airflow to the indoor heat exchanger, thereby improving its heat exchange efficiency and accelerating the evaporation process of the refrigerant, reducing liquid refrigerant residue. After the indoor fan speed is increased by 10 rpm for 3 minutes in step S723, step S724 is executed to determine if the condition is met. .

[0076] When step S724 determines that the condition is met... This indicates the compressor phase current fluctuation value after the indoor fan's operating speed increases by 10 rpm for 3 minutes. The compressor phase current fluctuation value before running for 3 minutes at a speed lower than the indoor fan's operating speed is increased by 10 rpm. This demonstrates that increasing the operating speed of the indoor fan can effectively reduce the phase current fluctuation value of the compressor. Then, step S721 is executed to further determine whether the condition is met. If so, then continue to execute step S722 to control the indoor fan speed to continue to increase at the preset speed. If the indoor fan speed has reached the maximum preset speed, then directly execute step S725 to control the opening of the electronic expansion valve to decrease to the second flow opening by the second preset number of steps.

[0077] When step S724 is determined not to be satisfied This indicates the compressor phase current fluctuation value after the indoor fan's operating speed increases by 10 rpm for 3 minutes. The phase current fluctuation value of the compressor before running for 3 minutes is equal to or greater than the operating speed of the indoor fan, increased by 10 rpm. This indicates that increasing the operating speed of the indoor fan cannot reduce the phase current fluctuation value of the compressor. Therefore, step S725 is executed to control the opening of the electronic expansion valve to decrease to the second flow opening by a second preset number of steps. The second preset number of steps is less than the first preset number of steps.

[0078] For example, the second preset number of steps is 5, so in step S725, the opening of the electronic expansion valve is controlled to decrease to the second flow opening by 5 steps. Then, step S726 is executed to control the electronic expansion valve to run at the second flow opening for an eighth preset time. Subsequently, step S721 is executed to continue to determine whether the condition is met. For example, the preset duration for the eighth time is 5 minutes.

[0079] Until step S721 determines that the condition is not met. That is, it is determined that the condition is not met. If the temperature is within a certain range, it indicates that there is no risk of liquid carryover during suction, meaning that the compressor does not have a risk of liquid slugging. Therefore, step S727 is executed to determine if the condition is met: the inlet temperature of the indoor heat exchanger. The refrigerant temperature of the indoor controller that dissipates heat at temperatures below 0°C or using refrigerant for heat dissipation. Less than the indoor dew point temperature If yes, proceed to step S719; otherwise, proceed to step S728.

[0080] When step S727 determines that the condition is met: or When the low-temperature cooling control method of this embodiment is applied to a conventional air conditioner model, the following condition is determined to be met: This indicates the inlet temperature of the indoor heat exchanger. If the temperature is below 0°C, there is a risk of frost or ice formation on the indoor heat exchanger (evaporator). When the low-temperature cooling control method of this embodiment is applied to a specially designed air conditioner model, the following conditions are determined to be met: This indicates the refrigerant temperature of the indoor controller that uses refrigerant for heat dissipation. Less than the indoor dew point temperature If the indoor controller that uses refrigerant for heat dissipation is at risk of condensation, then step S719 is executed to continue controlling the opening of the electronic expansion valve to increase to the first flow opening by the first preset number of steps, provided that there is no risk of liquid slugging in the compressor. This further increases the opening of the electronic expansion valve to further increase the inlet temperature of the indoor heat exchanger, thereby effectively preventing the indoor heat exchanger from frosting or icing, or the indoor controller that uses refrigerant for heat dissipation from condensation, which could lead to the air conditioner failing to cool at low temperatures.

[0081] When step S727 determines that the condition is not met: or When the low-temperature cooling control method of this embodiment is applied to a conventional air conditioner model, it is determined that the condition is not met: This indicates the inlet temperature of the indoor heat exchanger. If the temperature is equal to or greater than 0°C, there is no risk of frost or ice formation on the indoor heat exchanger (evaporator). However, when the low-temperature cooling control method of this embodiment is applied to a specially designed air conditioner model, the condition is determined not to be met. This indicates the refrigerant temperature of the indoor controller that uses refrigerant for heat dissipation. Equal to or greater than the indoor dew point temperature If the indoor controller that uses refrigerant for heat dissipation does not have the risk of condensation, and the current operating parameters of the air conditioner can meet the stability and reliability of the air conditioner's cooling operation in low-temperature environments, then step S728 is executed to control the opening of the electronic expansion valve to maintain the current first flow opening or the current second flow opening, so as to improve the stability and reliability of the air conditioner's cooling operation in low-temperature environments.

[0082] Therefore, the low-temperature cooling control method of this embodiment controls the air conditioner to perform anti-failure operations, such as adjusting the operating frequency of the compressor, adjusting the opening of the electronic expansion valve, and adjusting the operating speed of the indoor fan. This dynamically seeks the optimal low-temperature cooling operating parameters of the air conditioner, thereby preventing the indoor heat exchanger from frosting or icing, or the indoor controller that uses refrigerant for heat dissipation from condensation, which could lead to the risk of failure in low-temperature cooling. This ensures the heat exchange performance of the air conditioner in low-temperature cooling operation while improving the stability and reliability of the air conditioner's cooling operation in low-temperature environments.

[0083] Air conditioner example: The air conditioner in this embodiment includes an indoor unit and an outdoor unit with circuit boards. The circuit boards are equipped with a processor and a memory. The memory stores a computer program that can run on the processor. When the processor executes the computer program, it implements each step of the above-mentioned air conditioner low-temperature cooling control method.

[0084] For example, a computer program can be divided into one or more modules, one or more of which are stored in memory and executed by a processor to complete the various modules of the present invention. One or more modules can be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in a terminal device.

[0085] The processor referred to in this invention can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of an electrical appliance, connecting all parts of the appliance through various interfaces and lines.

[0086] Memory can be used to store computer programs and / or modules. The processor implements various functions of an electrical appliance by running or executing the computer programs and / or modules stored in the memory, and by accessing data stored in the memory. Memory can mainly include a program storage area and a data storage area. The program storage area can store the operating system, at least one application program required for a function, etc.; the data storage area can store data created based on the use of the electrical appliance, etc. Furthermore, memory can include high-speed random access memory, and can also include non-volatile memory, such as hard disks, RAM, plug-in hard disks, smart media cards (SMC), secure digital cards (SD cards), flash cards, at least one disk storage device, flash memory device, or other volatile solid-state storage devices.

[0087] Examples of computer-readable storage media: If the computer program stored in the air conditioner's memory is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above-described embodiments of the present invention can also be implemented by a computer program instructing related hardware. This computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the various steps of the above-described air conditioner low-temperature cooling control method.

[0088] Computer programs include computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. Computer-readable media can include: any entity or device capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in computer-readable media can be appropriately added to or subtracted according to the requirements of legislation and patent practice in a jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals.

[0089] The above embodiments are merely preferred examples of the present invention and are not intended to limit the scope of the present invention. Therefore, all equivalent changes or modifications made to the structure, features and principles of the present invention in accordance with the claims of the present invention should be included in the scope of the present invention patent application.

Claims

1. A method for controlling low-temperature cooling in an air conditioner, characterized in that, include: Control the air conditioner to operate in a preset cooling mode; When the outdoor ambient temperature Less than the preset low temperature threshold When it is determined that the air conditioner is in a low-temperature cooling state, the outdoor fan speed is controlled to run at a preset minimum speed or the outdoor fan is controlled to stop running. After the outdoor fan is running at a preset minimum speed or after the outdoor fan has stopped running for a first preset period of time, determine whether the following condition is met: the inlet temperature of the indoor heat exchanger. The refrigerant temperature of the indoor controller that dissipates heat at temperatures below 0°C or using refrigerant for heat dissipation. Less than the indoor dew point temperature If so, the air conditioner is controlled to perform a fail-safe operation; The failure prevention operation includes at least one of the following operations: adjusting the operating frequency of the compressor, adjusting the opening of the electronic expansion valve, and adjusting the operating speed of the indoor fan.

2. The low-temperature refrigeration control method for air conditioners according to claim 1, characterized in that: The failure prevention operation includes: The operating frequency of the compressor is controlled to decrease from a first preset frequency to a first frequency. run; When the compressor operates at the first frequency After running for the second preset duration, the first temperature difference is calculated and obtained. When the compressor operates at the first frequency After running for the third preset duration, the second temperature difference is calculated and obtained. ; Determine if it satisfies and If so, the operating frequency of the compressor is controlled to restore the operating frequency of the preset operating mode; in, For the compressor at the first frequency The inlet temperature of the indoor heat exchanger after running for the second preset time. For the compressor at the first frequency The inlet temperature of the indoor heat exchanger before the second preset operating time. For the compressor at the first frequency The inlet temperature of the indoor heat exchanger after the third preset running time. For the compressor at the first frequency The inlet temperature of the indoor heat exchanger before the third preset operating time. This is the first predetermined temperature difference.

3. The low-temperature refrigeration control method for air conditioners according to claim 2, characterized in that: When it is determined that the condition is not met. and If the condition is met, then determine whether the condition is satisfied: the inlet temperature of the indoor heat exchanger. The refrigerant temperature of the indoor controller that dissipates heat at temperatures below 0°C or using refrigerant for heat dissipation. Less than the indoor dew point temperature If so, the operating frequency of the compressor is controlled to continue decreasing from the first preset frequency to the first frequency. If not, control the compressor to maintain its current first operating frequency. run.

4. The air conditioner low-temperature cooling control method according to claim 2, characterized in that: The failure prevention operation also includes: When the compressor's operating frequency is restored to the preset operating mode's operating frequency, the compressor's operating frequency is then increased to a second preset frequency. run; When the compressor operates at the second frequency After running for the fourth preset duration, the third temperature difference is calculated and obtained. When the compressor operates at the second frequency After running for the fifth preset duration, the fourth temperature difference is calculated and obtained. ; Determine if it satisfies and If so, the operating frequency of the compressor is controlled to restore the operating frequency of the preset operating mode; in, For the compressor at the second frequency The inlet temperature of the indoor heat exchanger after the fourth preset running time. For the compressor at the second frequency The inlet temperature of the indoor heat exchanger before the fourth preset operating time. For the compressor at the second frequency The inlet temperature of the indoor heat exchanger after the fifth preset running time. For the compressor at the second frequency The inlet temperature of the indoor heat exchanger before the fifth preset operating time. This is the second predetermined temperature difference.

5. The low-temperature refrigeration control method for air conditioners according to claim 4, characterized in that: When it is determined that the condition is not met. and If the condition is met, then determine whether the condition is satisfied: the inlet temperature of the indoor heat exchanger. The refrigerant temperature of the indoor controller that dissipates heat at temperatures below 0°C or using refrigerant for heat dissipation. Less than the indoor dew point temperature If so, the operating frequency of the compressor is controlled to continue increasing from the second preset frequency to the second frequency. If not, control the compressor to maintain its current second operating frequency. run.

6. The low-temperature cooling control method for an air conditioner according to claim 4, characterized in that: The failure prevention operation also includes: When the operating frequency of the compressor is restored to the operating frequency of the preset operating mode, the opening of the electronic expansion valve is increased to the first flow opening by a first preset number of steps. After the electronic expansion valve operates at the first flow opening for a sixth preset time, it is determined whether the following conditions are met. If so, the operating speed of the indoor fan is increased to a preset speed. When the indoor fan operates at a preset speed for a seventh preset time, it is then determined whether the following conditions are met. If so, then check again whether the condition is met. If not, the opening of the electronic expansion valve is reduced to the second flow opening by a second preset number of steps, and the condition is checked again to determine whether the condition is met. ; Wherein, the second preset number of steps is less than the first preset number of steps. The phase current fluctuation value of the compressor after the electronic expansion valve has been running at the first flow opening for the sixth preset time. The preset liquid slugging constant of the compressor, The phase current fluctuation value of the compressor after the indoor fan operates at the preset speed for the seventh preset time. The phase current fluctuation value of the compressor is calculated by increasing the operating speed of the indoor fan by the preset speed before the seventh preset operating time.

7. The low-temperature refrigeration control method for an air conditioner according to claim 6, characterized in that: When it is determined that the condition is not met. If so, determine whether the condition is met: the inlet temperature of the indoor heat exchanger. The refrigerant temperature of the indoor controller that dissipates heat at temperatures below 0°C or using refrigerant for heat dissipation. Less than the indoor dew point temperature If so, the opening of the electronic expansion valve is controlled to continue increasing to the first flow opening by a first preset number of steps; otherwise, the opening of the electronic expansion valve is controlled to maintain the current first flow opening or maintain the current second flow opening.

8. The low-temperature refrigeration control method for an air conditioner according to claim 6, characterized in that: The maximum difference in phase current of the compressor is calculated once within a preset interval. : ； Calculate the ratio ; Then calculate and obtain ; in, The maximum phase current of the compressor within the preset interval time. The minimum phase current of the compressor within the preset interval time. This is a preset fluctuation value for when the compressor does not experience liquid slugging.

9. The air conditioner low-temperature refrigeration control method according to any one of claims 1 to 8, characterized in that: The indoor dew point temperature is calculated based on the indoor ambient temperature and humidity. .

10. An air conditioner, characterized in that, The device includes an indoor unit and an outdoor unit with circuit boards. The circuit boards are equipped with a processor and a memory. The memory stores a computer program. When the computer program is executed by the processor, it implements each step of the low-temperature cooling control method for an air conditioner according to any one of claims 1 to 9.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, it implements each step of the air conditioner low-temperature cooling control method according to any one of claims 1 to 9.

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