Air conditioner and control method thereof

Abstract

The invention discloses an air conditioner and a control method thereof.The air conditioner comprises a refrigerant circulation loop, an electronic expansion valve, an indoor coil pipe temperature sensor, an outdoor coil pipe temperature sensor, an outdoor environment temperature sensor, an exhaust temperature sensor, a condenser temperature sensor and a controller; controlling the air conditioner to enter a defrosting mode; and in the defrosting mode, the opening degree of the electronic expansion valve is controlled, after the frequency of the compressor is controlled to be reduced to the first preset frequency according to the first preset mode, the frequency of the compressor is controlled to be increased to the target operation frequency according to the second preset mode, and the opening degree of the electronic expansion valve is controlled to be adjusted to the first preset opening degree within the first preset time, and then the opening degree of the electronic expansion valve in the next period is controlled, the defrosting precision is improved, mistaken defrosting is avoided, the heating capacity of the air conditioner is guaranteed, meanwhile, the electronic expansion valve reaches the optimal opening degree, and liquid impact generated by a compressor during defrosting is prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioners, and more particularly to an air conditioner and a control method thereof. Background Art

[0002] In the prior art, the air conditioner defrosts according to the outdoor coil temperature, that is, when the outdoor coil temperature reaches a certain temperature, defrosting is started. Defrosting based on a single variable has problems such as incomplete defrosting at low temperatures, untimely frosting, and liquid slugging during defrosting. Therefore, it is necessary to provide an efficient defrosting control method. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, the object of the present invention is to provide an air conditioner and a control method thereof.

[0004] An air conditioner provided by the present invention includes: a refrigerant circulation circuit that enables the refrigerant to perform a refrigeration cycle in a circuit composed of a compressor, a condenser, an expansion valve, and an evaporator, where one of the condenser and the evaporator is an outdoor heat exchanger and the other is an indoor heat exchanger; an electronic expansion valve provided between the condenser and the evaporator, the electronic expansion valve being configured to increase the flow resistance of the refrigerant passing through the electronic expansion valve when its opening degree decreases, and decrease the flow resistance of the refrigerant passing through the electronic expansion valve when its opening degree increases; an indoor coil temperature sensor for detecting the indoor coil temperature; an outdoor coil temperature sensor for detecting the outdoor coil temperature; an outdoor ambient temperature sensor for detecting the outdoor ambient temperature; an exhaust temperature sensor for detecting the exhaust temperature of the compressor; a condenser temperature sensor for detecting the temperature in the middle of the condenser; a controller, the controller being configured to: when it is determined that the defrosting condition is met, control the air conditioner to enter the defrosting mode; in the defrosting mode, the controller controls the opening degree of the electronic expansion valve according to the temperature in the middle of the condenser, the indoor coil temperature, and the operating frequency of the compressor, until it is determined that the condition for exiting the defrosting mode is met, then control the compressor to reduce the frequency to a first preset frequency according to a first preset mode, and then control the compressor to increase the frequency to a target operating frequency according to a second preset mode, and within a first preset time, control the opening degree of the electronic expansion valve to be adjusted to a first preset opening degree, and then control the opening degree of the electronic expansion valve in the next cycle according to the operating frequency of the compressor, the opening degree of the electronic expansion valve in the previous cycle, the exhaust superheat degree in the previous cycle, the exhaust superheat degree in the cycle before the previous cycle, the current exhaust superheat degree, and the current target exhaust superheat degree, where the exhaust superheat degree is the difference between the exhaust temperature of the compressor and the temperature in the middle of the condenser.

[0005] In addition, the air conditioner according to the embodiment of the present invention may further have the following additional technical features:

[0006] Further, when determining that the defrosting condition is met, the controller is specifically configured as follows: when the continuous operation time of the compressor exceeds the preset heating operation time, and the cumulative heating operation time of the compressor is greater than the current defrosting interval time, and any one of the following three conditions is met, it is determined that the defrosting condition is met; wherein, Condition 1: The outdoor ambient temperature is within a first preset ambient temperature range, and for a continuous second preset time, the difference between the outdoor coil temperature and the outdoor ambient temperature is less than a corresponding first preset temperature, and the maximum temperature change amount of the outdoor coil temperature is greater than a second preset temperature, where different first preset ambient temperature ranges correspond to one first preset temperature; Condition 2: The outdoor ambient temperature is less than a third preset temperature, and the duration reaches a third preset time, and for a continuous fourth preset time, the difference between the outdoor coil temperature and the outdoor ambient temperature reaches a fourth preset temperature, and the maximum temperature change amount of the outdoor coil temperature is greater than a fifth preset temperature; Condition 3: The outdoor ambient temperature at the start of the compressor is less than a sixth preset temperature, and after the compressor starts for a fifth preset time, for a continuous sixth preset time, the outdoor ambient temperature is less than a seventh preset temperature, and the cumulative heating operation time of the compressor reaches a seventh preset time.

[0007] Further, when calculating the current defrosting interval time, the controller is specifically configured as follows: when the current defrosting time is greater than the previous defrosting time, the current defrosting interval time is the difference between the previous defrosting interval and an eighth preset time; when the current defrosting time is not greater than the previous defrosting time, the current defrosting interval time is the sum of the previous defrosting interval and the eighth preset time.

[0008] Further, when controlling the opening degree of the electronic expansion valve according to the temperature in the middle of the condenser, the indoor coil temperature, and the operating frequency of the compressor, the controller is specifically configured to execute the following formula:

[0009] P = a×F + b×(T 6 - T 5 ) + d;

[0010] wherein, P is the opening degree of the electronic expansion valve in the defrosting mode, F is the operating frequency of the compressor, T 6 is the indoor coil temperature, T 5 is the temperature in the middle of the condenser, and a, b, and d are respectively preset parameters.

[0011] Further, when determining that the condition for exiting the defrost mode is met, the controller is specifically configured to: when the current defrost time is greater than the preset defrost time, or; when the outdoor ambient temperature is within the second preset ambient temperature range and for the ninth preset continuous time, the outdoor coil temperature is greater than the corresponding eighth preset temperature, determine that the condition for exiting the defrost mode is met; wherein, different second preset ambient temperature ranges correspond to one eighth preset temperature.

[0012] Further, when controlling the compressor to reduce its frequency to the first preset frequency according to the first preset mode, the controller is specifically configured to: control the operating frequency of the compressor to decrease to the corresponding second preset frequency every tenth preset time until the frequency is reduced to the first preset frequency.

[0013] Further, when controlling the compressor to increase its frequency to the target operating frequency according to the second preset mode, the controller is specifically configured to: determine whether the target operating frequency is greater than the third preset frequency; when it is determined that the target operating frequency is greater than the third preset frequency, control the operating frequency of the compressor to rise to the third preset frequency, and after the tenth preset time, control the operating frequency of the compressor to continue to rise to the target operating frequency; when it is determined that the target operating frequency is not greater than the third preset frequency, control the operating frequency of the compressor to directly rise to the target operating frequency.

[0014] Further, when controlling the opening degree of the electronic expansion valve in the next cycle according to the operating frequency of the compressor, the opening degree of the electronic expansion valve in the previous cycle, the exhaust superheat degree in the previous cycle, the exhaust superheat degree in the cycle before the previous one, the current exhaust superheat degree, and the current target exhaust superheat degree, the controller is specifically configured to execute the following formula:

[0015] P 下 =P 上 +ΔK;

[0016] ΔK=A×D+B×(G 当 -G 目 )+C×V;

[0017]

[0018] V=(G 当 -G 上 )-(G 上 -G 上上 );

[0019] D=(G 当 -G 上 );

[0020] Wherein, P 下is the opening degree of the electronic expansion valve in the next cycle, P 上 is the opening degree of the electronic expansion valve in the previous cycle, ΔK is the change amount of the opening degree of the electronic expansion valve, D is the growth rate of the exhaust superheat degree, G 当 is the current exhaust superheat degree, G 目 is the current target exhaust superheat degree, G 上 is the exhaust superheat degree in the previous cycle, G 上上 is the exhaust superheat degree in the cycle before the previous cycle, V is the growth rate of the exhaust superheat degree, F 1 is the operating frequency of the compressor after exiting the defrosting mode, A, B, C, and M are preset parameters respectively, T is the preset number of cycles, and t is an integer between 1 and T.

[0021] Further, before determining that the defrosting condition is met, the controller is further configured to: when the air conditioner changes from a power-off state to a power-on state and the outdoor ambient temperature is lower than the ninth preset temperature, control the air conditioner to enter the heating mode, control the operating frequency of the compressor to be the fourth preset frequency, and control the outdoor fan to be turned off. After the eleventh preset time, control the air conditioner to enter the defrosting mode.

[0022] An air conditioner according to an embodiment of the present invention, the air conditioner includes: a refrigerant circulation circuit, an electronic expansion valve, an indoor coil temperature sensor, an outdoor coil temperature sensor, an outdoor ambient temperature sensor, an exhaust temperature sensor, a condenser temperature sensor, and a controller. Among them, the refrigerant circulation circuit enables the refrigerant to perform a refrigeration cycle in a circuit composed of a compressor, a condenser, an expansion valve, and an evaporator, and one of the condenser and the evaporator is an outdoor heat exchanger, and the other is an indoor heat exchanger; the electronic expansion valve is provided between the condenser and the evaporator, and the electronic expansion valve is used to increase the flow resistance of the refrigerant passing through the electronic expansion valve when its opening degree decreases, and to decrease the flow resistance of the refrigerant passing through the electronic expansion valve when its opening degree increases; the indoor coil temperature sensor is used to detect the indoor coil temperature; the outdoor coil temperature sensor is used to detect the outdoor coil temperature; the outdoor ambient temperature sensor is used to detect the outdoor ambient temperature; the exhaust temperature sensor is used to detect the exhaust temperature of the compressor; the condenser temperature sensor is used to detect the temperature in the middle of the condenser; the controller is configured to: when it is determined that the defrosting condition is met, control the air conditioner to enter the defrosting mode; in the defrosting mode, the controller controls the opening degree of the electronic expansion valve according to the temperature in the middle of the condenser, the indoor coil temperature, and the operating frequency of the compressor, until it is determined that the condition for exiting the defrosting mode is met, then control the compressor to reduce the frequency to a first preset frequency according to a first preset mode, and then control the compressor to increase the frequency to a target operating frequency according to a second preset mode, and within a first preset time, control the opening degree of the electronic expansion valve to be adjusted to a first preset opening degree, and then control the opening degree of the electronic expansion valve in the next cycle according to the operating frequency of the compressor, the opening degree of the electronic expansion valve in the previous cycle, the exhaust superheat degree in the previous cycle, the exhaust superheat degree in the cycle before the previous cycle, the current exhaust superheat degree, and the current target exhaust superheat degree, where the exhaust superheat degree is the difference between the exhaust temperature of the compressor and the temperature in the middle of the condenser, which improves the defrosting accuracy, avoids false defrosting, ensures the heating capacity of the air conditioner, and at the same time makes the electronic expansion valve reach the optimal opening degree, prevents the compressor from generating liquid slugging during defrosting, and enables the internal pressure of the air conditioner to quickly reach equilibrium.

[0023] In view of the above problems, the present invention further provides a control method for an air conditioner, which is used for the air conditioner described in any of the above embodiments. The method includes the following steps: when it is determined that the defrosting condition is satisfied, control the air conditioner to enter the defrosting mode; in the defrosting mode, control the opening degree of the electronic expansion valve according to the temperature in the middle of the condenser, the indoor coil temperature, and the operating frequency of the compressor, until it is determined that the condition for exiting the defrosting mode is satisfied, control the compressor to reduce the frequency to a first preset frequency according to a first preset mode, then control the compressor to increase the frequency to a target operating frequency according to a second preset mode, and within a first preset time, control the opening degree of the electronic expansion valve to be adjusted to a first preset opening degree, and then control the opening degree of the electronic expansion valve in the next cycle according to the operating frequency of the compressor, the opening degree of the electronic expansion valve in the previous cycle, the exhaust superheat degree in the previous cycle, the exhaust superheat degree in the cycle before the previous cycle, the current exhaust superheat degree, and the current target exhaust superheat degree, where the exhaust superheat degree is the difference between the exhaust temperature of the compressor and the temperature in the middle of the condenser.

[0024] According to the control method of the air conditioner of the embodiment of the present invention, when it is determined that the defrosting condition is satisfied, control the air conditioner to enter the defrosting mode. In the defrosting mode, control the opening degree of the electronic expansion valve according to the temperature in the middle of the condenser, the indoor coil temperature, and the operating frequency of the compressor. Until it is determined that the condition for exiting the defrosting mode is satisfied, control the compressor to reduce the frequency to a first preset frequency according to a first preset mode, then control the compressor to increase the frequency to a target operating frequency according to a second preset mode, and within a first preset time, control the opening degree of the electronic expansion valve to be adjusted to a first preset opening degree, and then control the opening degree of the electronic expansion valve in the next cycle according to the operating frequency of the compressor, the opening degree of the electronic expansion valve in the previous cycle, the exhaust superheat degree in the previous cycle, the exhaust superheat degree in the cycle before the previous cycle, the current exhaust superheat degree, and the current target exhaust superheat degree, where the exhaust superheat degree is the difference between the exhaust temperature of the compressor and the temperature in the middle of the condenser. This improves the defrosting accuracy, avoids false defrosting, ensures the heating capacity of the air conditioner, and at the same time makes the electronic expansion valve reach the optimal opening degree, prevents liquid hammer of the compressor during defrosting, and enables the internal pressure of the air conditioner to quickly reach balance.

[0025] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of the embodiments in conjunction with the accompanying drawings, where:

[0027] Figure 1 is a schematic structural diagram of an air conditioner according to an embodiment of the present invention;

[0028] Figure 2 It is a schematic structural diagram of a controller according to an embodiment of the present invention;

[0029] Figure 3 It is a schematic structural diagram of an air conditioner according to another embodiment of the present invention;

[0030] Figure 4 It is a flowchart for determining that the defrosting condition is met according to an embodiment of the present invention;

[0031] Figure 5 It is a flowchart for controlling the defrosting interval time according to an embodiment of the present invention;

[0032] Figure 6 It is a flowchart for determining to exit the defrosting mode according to an embodiment of the present invention;

[0033] Figure 7 It is a flowchart for controlling the compressor to increase the frequency to the target operating frequency according to the second preset mode according to an embodiment of the present invention;

[0034] Figure 8 It is a flowchart of a control method for an air conditioner according to an embodiment of the present invention. Detailed implementation manners

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0037] The terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0038] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] An embodiment of the present application provides an air conditioner 10. Referring to Figure 1 , the air conditioner 10 includes a refrigeration system for exchanging heat with indoor air to meet the refrigeration or heating requirements.

[0040] The refrigeration system includes a compressor, a condenser, an electronic expansion valve 12, and an evaporator. In the present application, the air conditioner 10 performs the refrigeration cycle of the air conditioner 10 by using the compressor, the condenser, the electronic expansion valve 12, and the evaporator. The refrigeration cycle includes a series of processes involving compression, condensation, expansion, and evaporation, and supplies refrigerant to the conditioned and heat-exchanged air.

[0041] The compressor compresses the refrigerant gas in a high-temperature and high-pressure state and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and heat is released to the surrounding environment through the condensation process.

[0042] The electronic expansion valve 12 expands the liquid-phase refrigerant in a high-temperature and high-pressure state condensed in the condenser into a low-pressure liquid-phase refrigerant. The evaporator evaporates the refrigerant expanded in the electronic expansion valve 12 and returns the refrigerant gas in a low-temperature and low-pressure state to the compressor.

[0043] The evaporator can achieve a refrigeration effect by using the latent heat of evaporation of the refrigerant to exchange heat with the material to be cooled. Throughout the cycle, the air conditioner 10 can adjust the temperature of the indoor space.

[0044] The outdoor unit 2 of the air conditioner 10 refers to the part of the refrigeration cycle including the compressor and the outdoor heat exchanger. The indoor unit 1 of the air conditioner 10 includes an indoor heat exchanger, and the electronic expansion valve 12 can be provided in the indoor unit 1 or the outdoor unit 2.

[0045] The indoor heat exchanger and the outdoor heat exchanger serve as condensers or evaporators. When the indoor heat exchanger serves as a condenser, the air conditioner 10 serves as a heater in the heating mode. When the indoor heat exchanger serves as an evaporator, the air conditioner 10 serves as a cooler in the cooling mode.

[0046] The air conditioner 10 in this application includes an indoor unit 1 and an outdoor unit 2. The indoor unit 1 and the outdoor unit 2 can be set as an integrated unit or a split unit. The indoor unit 1 can be set as a wall-mounted unit, a ceiling unit, a duct unit, etc., and the indoor unit 1 is installed on the top or upper part of the indoor room.

[0047] Referring to Figure 1 , taking the indoor wall-mounted unit as an example, the indoor wall-mounted unit is usually installed at positions such as the indoor wall surface. Again, for example, an indoor cabinet unit (not shown in the figure) is also a form of the indoor unit 1 of the indoor unit 1.

[0048] Taking the split unit as an example, the air conditioner 10 includes an indoor unit 1 and an outdoor unit 2. Among them, the outdoor unit 2 is usually set outdoors and is used for heat exchange with the indoor environment.

[0049] In addition, as shown in the figure, the air conditioner 10 is equipped with a controller 71 to control the operation of each component in the internal air conditioner 10, so that each component of the air conditioner 10 operates to achieve each predetermined function of the air conditioner 10. Among them, a control device 200 is also attached to the air conditioner 10. Exemplarily, the control device 200 is specifically set as a remote controller, and the remote controller has a function of communicating with the controller 71 using, for example, infrared rays or other communication methods. The remote controller is used for users to perform various controls on the air conditioner 10 to realize the interaction between the user and the air conditioner 10.

[0050] The indoor unit 1 of the air conditioner 10 in the embodiment of this application is set on the top or upper part of the indoor. Generally speaking, the installation height of the indoor unit 1 is higher than the user activity area. The indoor unit 1 includes an air return port and an air outlet communicating with the indoor. The indoor air passes through the air return port into the indoor unit 1 and flows back into the indoor through the air outlet.

[0051] The refrigerant circulation circuit in this application circulates the refrigerant in a circuit composed of a compressor, a condenser, an electronic expansion valve 12, and an evaporator. One of the condenser and the evaporator is an outdoor heat exchanger, and the other is an indoor heat exchanger. The indoor heat exchanger is used for heat exchange with the air in the indoor unit 1, and the outdoor unit 2 heat exchanger is used for heat exchange with the air in the outdoor unit 2, so as to meet the cooling or heating requirements of the air conditioner 10.

[0052] An indoor fan is also included in the indoor unit 1. The indoor fan is arranged near the air return port or the air outlet of the indoor heat exchanger and is used to send the heat-exchanged air to the indoor. The indoor fan includes multiple gears and is used to change the air outlet speed of the air flow at the air outlet.

[0053] A wind deflector is arranged at the position of the air outlet. By changing its relative rotation angle with the air outlet, the wind deflector adjusts the outflow direction of the air flowing through the air outlet, thereby affecting the stratification of the indoor air temperature.

[0054] In the embodiment shown in the present application, the air conditioner 10 further includes a controller 71. The controller 71 refers to a device that can generate operation control signals according to instruction operation codes and timing signals to instruct the air conditioner 10 to execute control instructions. For example, in response to a power-on or power-off instruction issued by a user received, the controller 71 can perform operations related to the object selected by the power-on or power-off instruction.

[0055] The embodiment of the present application further provides a schematic diagram of the hardware structure of the controller 71, as Figure 2 shown. The controller 71 includes a processor 83. Optionally, it further includes a memory 82 and a communication interface 84 connected to the processor 83. The processor 83, the memory 82, and the communication interface 84 are connected through a bus 81.

[0056] The processor 83 can be a central processing unit 83 (CPU), a general-purpose processor 83, a network processor 83 (NP), a digital signal processor 83 (DSP), a microprocessor 83, a microcontroller 718, a programmable logic device (PLD), or any combination thereof. The processor 83 can also be any other device with processing functions, such as a circuit, a device, or a software module. The processor 83 can also include multiple CPUs, and the processor 83 can be a single-core (single-CPU) processor 83 or a multi-core (multi-CPU) processor 83. Here, the processor 83 can refer to one or more devices, circuits, or processing cores for processing data (such as computer program instructions).

[0057] The memory 82 can be a read-only memory (ROM), or other types of static storage devices that can store static information and instructions, a random access memory (RAM), or other types of dynamic storage devices that can store information and instructions. It can also be an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM), or other optical disc storage, optical disc storage (including compact discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.), magnetic disk storage media, or other magnetic storage devices, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer. The embodiments of the present application do not impose any restrictions on this. The memory 82 can exist independently or be integrated with the processor 83. Among them, the memory 82 can contain computer program code. The processor 83 is used to execute the computer program code stored in the memory 82, thereby implementing the control method of the air conditioner provided by the embodiments of the present application.

[0058] The communication interface 84 can be used to communicate with other devices or communication networks (such as Ethernet, radio access network (RAN), wireless local area networks (WLAN), etc.). The communication interface 84 can be a module, a circuit, a transceiver, or any device capable of implementing communication.

[0059] The bus 81 can be a peripheral component interconnect (PCI) bus 81 or an extended industry standard architecture (EISA) bus 81, etc. The bus 81 can be divided into an address bus 81, a data bus 81, a control bus 81, etc. For the sake of representation, Figure 2 only a thick line is used to represent it in the figure, but it does not mean that there is only one bus 81 or one type of bus 81.

[0060] The following refers to Figures 3 - 8 describe the air conditioner and its control method according to the embodiments of the present invention.

[0061] Figure 3 is a schematic structural diagram of an air conditioner according to an embodiment of the present invention. As Figure 3As shown, an air conditioner 10 includes: a refrigerant circulation circuit 11, an electronic expansion valve 12, an indoor coil temperature sensor 13, an outdoor coil temperature sensor 14, an outdoor ambient temperature sensor 15, an exhaust temperature sensor 16, a condenser temperature sensor 17, and a controller 71. Among them, the refrigerant circulation circuit 11 enables the refrigerant to perform a refrigeration cycle in a circuit composed of a compressor, a condenser, an expansion valve, and an evaporator. One of the condenser and the evaporator is an outdoor heat exchanger, and the other is an indoor heat exchanger; the electronic expansion valve 12 is provided between the condenser and the evaporator. When the opening degree of the electronic expansion valve 12 decreases, the flow resistance of the refrigerant passing through the electronic expansion valve 12 increases, and when the opening degree increases, the flow resistance of the refrigerant passing through the electronic expansion valve 12 decreases; the indoor coil temperature sensor 13 is used to detect the indoor coil temperature; the outdoor coil temperature sensor 14 is used to detect the outdoor coil temperature; the outdoor ambient temperature sensor 15 is used to detect the outdoor ambient temperature; the exhaust temperature sensor 16 is used to detect the exhaust temperature of the compressor; the condenser temperature sensor 17 is used to detect the temperature in the middle of the condenser; the controller 71 is configured to: when it is determined that the defrosting condition is met, control the air conditioner to enter the defrosting mode; in the defrosting mode, the controller 71 controls the opening degree of the electronic expansion valve 12 according to the temperature in the middle of the condenser, the indoor coil temperature, and the operating frequency of the compressor until it is determined that the condition for exiting the defrosting mode is met. Then, control the compressor to reduce the frequency to a first preset frequency according to a first preset mode, and then control the compressor to increase the frequency to a target operating frequency according to a second preset mode, and within a first preset time, control the opening degree of the electronic expansion valve 12 to be adjusted to a first preset opening degree. After that, control the opening degree of the electronic expansion valve 12 in the next cycle according to the operating frequency of the compressor, the opening degree of the electronic expansion valve 12 in the previous cycle, the exhaust superheat degree in the previous cycle, the exhaust superheat degree in the cycle before the previous cycle, the current exhaust superheat degree, and the current target exhaust superheat degree. Among them, the exhaust superheat degree is the difference between the exhaust temperature of the compressor and the temperature in the middle of the condenser.

[0062] Specifically, after the air conditioner enters the defrosting mode, it will heat the surface of the condenser to melt the frost. If defrosting is carried out at an inappropriate time, it will affect the heating capacity of the air conditioner, cause the indoor temperature to drop, result in a waste of energy, and affect the working efficiency of the air conditioner. Therefore, in the embodiments of the present invention, the start of the defrosting mode is restricted by setting defrosting conditions to prevent misdefrosting and overdefrosting. In the defrosting mode, the temperature in the middle of the condenser characterizes the degree of frosting on the surface of the condenser, the indoor coil temperature is used to judge the working state of the air conditioner, and the operating frequency of the compressor reflects the load and demand of the air conditioner. Therefore, the controller 71 controls the opening degree of the electronic expansion valve 12 according to the temperature in the middle of the condenser, the indoor coil temperature, and the operating frequency of the compressor to control the refrigerant flow rate to adapt to the actual demand of the air conditioner. Until it is determined that the condition for exiting the defrosting mode is met, the compressor is controlled to reduce the frequency to the first preset frequency according to the first preset mode, and then the compressor is controlled to increase the frequency to the target operating frequency according to the second preset mode, so that the compressor frequency decreases in a gradient and then increases, preventing the opening degree of the electronic expansion valve 12 from being too large and causing the phenomenon of liquid slugging of the refrigerant in the compressor. And within the first preset time, the opening degree of the electronic expansion valve 12 is controlled to be adjusted to the first preset opening degree to avoid excessive pressure between the evaporator and the condenser, and the internal pressure of the air conditioner is smoothly transitioned to the normal pressure by controlling the opening degree of the electronic expansion valve 12, preventing the phenomenon of liquid slugging of the refrigerant in the compressor. Then, according to the operating frequency of the compressor, the opening degree of the electronic expansion valve 12 in the previous cycle, the exhaust superheat degree in the previous cycle, the exhaust superheat degree in the cycle before the previous cycle, the current exhaust superheat degree, and the current target exhaust superheat degree, the opening degree of the electronic expansion valve 12 in the next cycle is controlled. Among them, the exhaust superheat degree is the difference between the exhaust temperature of the compressor and the temperature in the middle of the condenser, so as to control the electronic expansion valve 12 through the change of the exhaust superheat degree, make the opening degree of the electronic expansion valve 12 reach the optimal opening degree, achieve the best defrosting effect, and at the same time prevent the phenomenon of liquid slugging of the compressor during defrosting.

[0063] In one embodiment of the present invention, as Figure 4As shown, when it is determined that the defrosting condition is satisfied, the controller 71 is specifically configured to: when the continuous operation time of the compressor exceeds the preset heating operation time, and the cumulative heating operation time of the compressor is greater than the current defrosting interval time, and any one of the following three conditions is satisfied, it is determined that the defrosting condition is satisfied; among them, Condition 1: The outdoor ambient temperature is within the first preset ambient temperature range, and for a continuous second preset time, the difference between the outdoor coil temperature and the outdoor ambient temperature is less than the corresponding first preset temperature, and the maximum temperature change of the outdoor coil temperature is greater than the second preset temperature, where different first preset ambient temperature ranges correspond to a first preset temperature; Condition 2: The outdoor ambient temperature is less than the third preset temperature, and the duration reaches the third preset time, and for a continuous fourth preset time, the difference between the outdoor coil temperature and the outdoor ambient temperature reaches the fourth preset temperature, and the maximum temperature change of the outdoor coil temperature is greater than the fifth preset temperature; Condition 3: The outdoor ambient temperature at the start of the compressor is less than the sixth preset temperature, and after the compressor starts for the fifth preset time, for a continuous sixth preset time, the outdoor ambient temperature is less than the seventh preset temperature, and the cumulative heating operation time of the compressor reaches the seventh preset time.

[0064] Specifically, when the continuous operation time of the compressor exceeds the preset heating operation time, and the cumulative heating operation time of the compressor is greater than the defrosting time interval of this time, it is considered that the frequent interruption of the heating mode of the air conditioner to enter the defrosting mode can be avoided, which helps to improve the performance and efficiency of the air conditioner. Under this condition, when any one of the following three conditions is met, it is considered that the defrosting mode can be turned on. Condition 1: The outdoor ambient temperature is within the first preset ambient temperature range, and for a continuous second preset time, the difference between the outdoor coil temperature and the outdoor ambient temperature is less than the corresponding first preset temperature, and the maximum temperature change of the outdoor coil temperature is greater than the second preset temperature. It is considered that frosting occurs on the condenser and the defrosting mode needs to be turned on. Specifically, as shown in Table 1, when the outdoor ambient temperature is within different temperature ranges, the first preset temperature corresponding to the difference △T between the outdoor coil temperature and the outdoor ambient temperature is different, which is used as the basis for judging whether the air conditioner frosts in different temperature ranges, where M1, M2, M3, and M4 are calibrated through experiments and stored in the controller 71; Condition 2: The outdoor ambient temperature is less than the third preset temperature, and the duration reaches the third preset time, and for a continuous fourth preset time, the difference between the outdoor coil temperature and the outdoor ambient temperature reaches the fourth preset temperature, and the maximum temperature change of the outdoor coil temperature is greater than the fifth preset temperature. It is considered that frosting occurs on the condenser and the defrosting mode needs to be turned on. The third preset temperature, the fourth preset time, the fourth preset temperature, and the fifth preset time are calibrated through experiments and stored in the controller 71; Condition 3: The outdoor ambient temperature at the start of the compressor is less than the sixth preset temperature, and after the compressor starts for the fifth preset time, for a continuous sixth preset time, the outdoor ambient temperature is less than the seventh preset temperature, and the cumulative heating operation time of the compressor reaches the seventh preset time. It is considered that frosting occurs on the condenser and the defrosting mode needs to be turned on. It is considered that frosting occurs on the condenser and the defrosting mode needs to be turned on. The sixth preset temperature, the fifth preset time, the sixth preset time, and the seventh preset temperature are calibrated through experiments and stored in the controller 71.

[0065] In a specific embodiment, when the outdoor ambient temperature T0 is within the first preset temperature range, for example, 0°C ≤ T0 < 7°C, and the difference △T between the outdoor coil temperature and the outdoor ambient temperature does not exceed the first preset temperature M1°C shown in Table 1 for a second preset time, for example, 1 minute, and the maximum temperature change of the outdoor coil temperature is greater than the second preset temperature, for example, 3°C, at this time, Condition 1 is satisfied, and it is considered that the condenser has a frosting phenomenon and the defrosting mode needs to be activated; when the outdoor ambient temperature is less than the third preset temperature, for example, 7°C, for a third preset time, for example, 2 hours, and the difference △T between the outdoor coil temperature and the outdoor ambient temperature reaches the fourth preset temperature, for example, 5°C, for a fourth time, for example, 1 minute, and the maximum temperature change of the outdoor coil temperature is greater than the fifth preset temperature, for example, 2°C, it is considered that Condition 2 is satisfied, the condenser has a frosting phenomenon, and the defrosting mode needs to be activated; when the outdoor ambient temperature at the start of the compressor is less than the sixth preset temperature, for example, 7°C, and after the compressor starts for a fifth preset time, for example, 10 minutes, the outdoor ambient temperature is less than the seventh preset temperature, for example, 2°C, for a sixth preset time, for example, 1 minute, and the cumulative heating operation time of the compressor reaches the seventh preset time, for example, 3 hours, it is considered that Condition 3 is satisfied, the condenser has a frosting phenomenon, and the defrosting mode needs to be activated.

[0066] Outdoor ambient temperature T0 △T 0℃≤T0＜7℃ △T ≤ M1 -5℃≤T0＜0℃ △T ≤ M2 -8℃≤T0＜-5℃ △T ≤ M3 T0＜-8℃ △T ≤ M4

[0067] Table 1

[0068] In an embodiment of the present invention, as Figure 5 shown, when calculating the defrosting interval time for this time, the controller 71 is specifically configured as follows: when the defrosting time for this time is greater than the defrosting time for the previous time, the defrosting interval time for this time is the difference between the defrosting interval for the previous time and the eighth preset time; when the defrosting time for this time is not greater than the defrosting time for the previous time, the defrosting interval time for this time is the sum of the defrosting interval for the previous time and the eighth preset time.

[0069] Specifically, when the defrosting time for this time is greater than the defrosting time for the previous time, it is considered that the frosting degree of the condenser is greater than that of the previous time. To defrost the condenser in a timely manner, the defrosting interval time for this time is set as the difference between the defrosting interval for the previous time and the eighth preset time, so as to reduce the defrosting interval time for this time and avoid excessive frosting from affecting the performance of the air conditioner; when the frosting time for this time is not greater than the defrosting time for the previous time, it is considered that the frosting degree of the condenser is less than that of the previous time, and there is no need to defrost the condenser frequently. Therefore, the defrosting interval time for this time is set as the sum of the defrosting interval time for the previous time and the eighth preset time, so as to increase the defrosting interval time for this time and avoid frequent defrosting of the condenser, which affects the performance of the air conditioner.

[0070] In a specific embodiment, when the defrosting time this time is greater than the defrosting time last time, the defrosting interval time this time is set to the difference between the defrosting interval last time, for example 45 minutes, and the eighth preset time, for example 1 minute, that is, 44 minutes, so as to reduce the defrosting interval time this time and avoid excessive frosting from affecting the performance of the air conditioner; when the frosting time this time is not greater than the defrosting time last time, the defrosting interval time this time is set to the sum of the defrosting interval time last time, for example 50 minutes, and the eighth preset time, for example 1 minute, that is, 51 minutes, so as to increase the defrosting interval time this time and avoid frequent defrosting of the condenser, which affects the performance of the air conditioner.

[0071] In an embodiment of the present invention, when controlling the opening degree of the electronic expansion valve 12 according to the temperature in the middle of the condenser, the indoor coil temperature, and the operating frequency of the compressor, the controller 71 is specifically configured to execute the following formula:

[0072] P = a×F + b×(T 6 -T 5 ) + d;

[0073] Wherein, P is the opening degree of the electronic expansion valve 12 in the defrosting mode, F is the operating frequency of the compressor, T 6 is the indoor coil temperature, T 5 is the temperature in the middle of the condenser, and a, b, and d are respectively preset parameters.

[0074] Specifically, the values of the parameters a, b, and d are calibrated through experiments according to each model and stored in the controller 71. Among them, the range of the parameter a is set between -20 and 20, the range of the parameter b is set between -20 and 20, and the range of the parameter c is set between -500 and 500. In the embodiment of the present invention, the opening degree of the electronic expansion valve 12 is controlled according to the temperature in the middle of the condenser, the indoor coil temperature, and the operating frequency of the compressor. The part of a×F is used to adapt to the change of the operating frequency of the air conditioner compressor, and the part of b×(T 6 -T 5 ) adjusts the opening degree of the electronic expansion valve 12 according to the difference between the indoor coil temperature and the temperature in the middle of the condenser, ensures the normal operation of the air conditioner during the defrosting process, prevents the refrigerant from experiencing liquid hammer phenomenon in the compressor, and the part of d provides additional adjustment to adapt to the differences of various models.

[0075] In an embodiment of the present invention, as Figure 6 shown, when it is determined that the condition for exiting the defrosting mode is met, the controller 71 is specifically configured to: when the defrosting time this time is greater than the preset defrosting time, or; when the outdoor ambient temperature is in the second preset ambient temperature range and the outdoor coil temperature is greater than the corresponding eighth preset temperature for the continuous ninth preset time, it is determined that the condition for exiting the defrosting mode is met; wherein, different second preset ambient temperature ranges correspond to an eighth preset temperature.

[0076] Specifically, when the current defrosting time is greater than the preset defrosting time, in order to prevent the defrosting time from being too long and affecting the working efficiency of the air conditioner, it is considered that the condition for exiting the defrosting mode is met; or, when the outdoor ambient temperature is within the second preset ambient temperature range and the outdoor coil temperature is greater than the corresponding eighth preset temperature for the ninth preset continuous time, it is considered that defrosting does not need to continue and the condition for exiting the defrosting mode is met. It can be understood that in different ambient temperature ranges, the outdoor coil temperature reaches its corresponding temperature to complete defrosting. Therefore, different second preset ambient temperature ranges correspond to an eighth preset temperature. The preset defrosting time, the second preset ambient temperature, the ninth preset time, and the eighth preset temperature are calibrated through experiments and stored in the controller 71.

[0077] In a specific embodiment, in different ambient temperature ranges, the indoor coil temperature ranges corresponding to determining the exit of the defrosting mode are also different. As shown in Table 2, when the outdoor ambient temperature is within the second preset ambient temperature range, for example, not less than -8°C, and the outdoor coil temperature is greater than the corresponding eighth preset temperature, for example, 17°C, and lasts for 10 seconds, it is considered that defrosting is completed and the condition for exiting the defrosting mode is met; when the outdoor ambient temperature is within the second preset ambient temperature range, for example, not less than -8°C, and the outdoor coil temperature is greater than the corresponding eighth preset temperature, for example, 20°C, and lasts for 5 seconds, it is considered that defrosting is completed and the condition for exiting the defrosting mode is met; when the outdoor ambient temperature is within the second preset ambient temperature range, for example, less than -8°C, and the outdoor coil temperature is greater than the corresponding eighth preset temperature, for example, 15°C, and lasts for 10 seconds, it is considered that defrosting is completed and the condition for exiting the defrosting mode is met.

[0078]

[0079]

[0080] Table 2

[0081] In an embodiment of the present invention, when controlling the compressor to reduce its frequency to the first preset frequency according to the first preset mode, the controller 71 is specifically configured to: control the operating frequency of the compressor to decrease to the corresponding second preset frequency every tenth preset time until it is reduced to the first preset frequency.

[0082] Specifically, the first preset frequency is the defrosting preparation frequency. The first preset mode is to set five frequency reduction buffer platforms between the current compressor frequency and the first preset frequency, and decrease to the corresponding second preset frequency every tenth preset time until it is reduced to the first preset frequency. This process aims to ensure that there is a buffer during frequency reduction to prevent the occurrence of liquid hammer in the compressor. The tenth preset time, the second preset frequency, and the first preset frequency are calibrated through experiments and stored in the controller 71.

[0083] In a specific embodiment, the compressor is controlled to drop to a corresponding second preset frequency, for example, 5HZ, every tenth preset time, for example, 30 seconds, that is, it drops to a frequency reduction buffer platform, and this is done five times until the frequency is reduced to a first preset frequency, for example, 30HZ. It should be noted that different air conditioner models correspond to different first preset frequencies.

[0084] In an embodiment of the present invention, as Figure 7 shown, when controlling the compressor to increase its frequency to the target operating frequency according to the second preset mode, the controller 71 is specifically configured to: determine whether the target operating frequency is greater than a third preset frequency; when it is determined that the target operating frequency is greater than the third preset frequency, control the operating frequency of the compressor to rise to the third preset frequency, and after the tenth preset time, control the operating frequency of the compressor to continue to rise to the target operating frequency; when it is determined that the target operating frequency is not greater than the third preset frequency, control the operating frequency of the compressor to directly rise to the target operating frequency.

[0085] Specifically, the target operating frequency is the heating target frequency of the air conditioner before starting the defrosting mode. After the defrosting is completed, the compressor needs to be increased in frequency to the target operating frequency according to the second preset mode to continue executing the heating mode. Before the compressor increases its frequency, it is determined whether the target operating frequency is greater than a third preset frequency, for example, 45HZ. When it is determined that the target operating frequency is greater than the third preset frequency, it is considered that the gap between the target operating frequency and the current operating frequency of the compressor is large. If the frequency is directly increased, it may cause a liquid slugging phenomenon inside the compressor. Therefore, the operating frequency of the compressor is controlled to rise to the third preset frequency to prevent the compressor from increasing its frequency too quickly and causing a liquid slugging phenomenon inside the compressor, and after the tenth preset time, for example, 20 seconds, the operating frequency of the compressor is controlled to continue to rise to the target operating frequency to achieve a smooth and safe frequency increase operation; when it is determined that the target operating frequency is not greater than the third preset frequency, it is considered that no liquid slugging phenomenon will occur during direct frequency increase, and the operating frequency of the compressor is directly controlled to rise to the target operating frequency.

[0086] In an embodiment of the present invention, when controlling the opening degree of the electronic expansion valve 12 in the next cycle according to the operating frequency of the compressor, the opening degree of the electronic expansion valve 12 in the previous cycle, the exhaust superheat degree in the previous cycle, the exhaust superheat degree in the cycle before the previous cycle, the current exhaust superheat degree, and the current target exhaust superheat degree, the controller 71 is specifically configured to execute the following formula:

[0087] P 下 = P 上 + ΔK;

[0088] ΔK = A × D + B × (G 当 - G 目 ) + C × V;

[0089]

[0090] V = (G 当 - G 上 ) - (G 上 - G 上上 );

[0091] D = (G 当 - G 上 );

[0092] Wherein, P 下 is the opening degree of the electronic expansion valve 12 in the next cycle, P 上 is the opening degree of the electronic expansion valve 12 in the previous cycle, ΔK is the change amount of the opening degree of the electronic expansion valve 12, D is the growth rate of the exhaust superheat degree, G 当 is the current exhaust superheat degree, G 目 is the current target exhaust superheat degree, G 上 is the exhaust superheat degree in the previous cycle, G 上上 is the exhaust superheat degree in the cycle before the previous cycle, V is the growth rate of the exhaust superheat degree, F 1 is the operating frequency of the compressor after exiting the defrosting mode, A, B, C, and M are respectively preset parameters, T is the preset number of cycles, and t is an integer between 1 and T.

[0093] Specifically, the controller 71 collects the exhaust superheat degree once every 1 second. Therefore, the calculation formulas for the growth rate D of the exhaust superheat degree and the growth rate V of the exhaust superheat degree are respectively V = (G 当 - G 上 ) - (G 上 - G 上上 ) and D = (G 当 - G 上 ). In the embodiment of the present invention, the change amount of the electronic expansion valve 12 in the next cycle is controlled by the opening degree of the electronic expansion valve 12 in the previous cycle and the change amount of the opening degree of the electronic expansion valve 12, so as to respond to the change of the actual operating conditions in a timely manner. At the same time, the growth rate D of the exhaust superheat degree and the growth rate V of the exhaust superheat degree are introduced, effectively preventing the occurrence of liquid hammer phenomenon.

[0094] In an embodiment of the present invention, before it is determined that the defrosting condition is satisfied, the controller 71 is further configured to: when the air conditioner changes from the power-off state to the power-on state and the outdoor ambient temperature is less than the ninth preset temperature, control the air conditioner to enter the heating mode, control the operating frequency of the compressor to be the fourth preset frequency, and control the outdoor fan to be turned off. After the eleventh preset time, control the air conditioner to enter the defrosting mode.

[0095] Specifically, before determining that the defrosting condition is met, when the air conditioner changes from the power-off state to the power-on state and the outdoor ambient temperature is lower than the ninth preset temperature, for example, 7°C, the air conditioner is controlled to enter the heating mode to ensure that the air conditioner is free of faults. The operating frequency of the compressor is controlled to be the fourth preset frequency for heating, so that the surface of the condenser quickly condenses, and the outdoor fan is controlled to turn off for the eleventh preset time, for example, 10 minutes. During this period, the evaporation temperature is lower than 0°C, and the condensed water quickly forms frost. After the compressor operates for 10 minutes, at this time, the temperature of the condenser is relatively high, and the frost layer can be quickly melted. The melted frost turns into ice water and takes away the dust on the surface of the condenser to ensure the cleanliness of the condenser surface.

[0096] The air conditioner 10 according to an embodiment of the present invention includes: a refrigerant circulation circuit 11, an electronic expansion valve 12, an indoor coil temperature sensor 13, an outdoor coil temperature sensor 14, an outdoor ambient temperature sensor 15, an exhaust temperature sensor 16, a condenser temperature sensor 17, and a controller 71. Among them, the refrigerant circulation circuit 11 enables the refrigerant to perform a refrigeration cycle in a circuit composed of a compressor, a condenser, an expansion valve, and an evaporator. One of the condenser and the evaporator is an outdoor heat exchanger, and the other is an indoor heat exchanger; the electronic expansion valve 12 is arranged between the condenser and the evaporator. When the opening of the electronic expansion valve 12 decreases, the flow resistance of the refrigerant passing through the electronic expansion valve 12 increases, and when the opening increases, the flow resistance of the refrigerant passing through the electronic expansion valve 12 decreases; the indoor coil temperature sensor 13 is used to detect the indoor coil temperature; the outdoor coil temperature sensor 14 is used to detect the outdoor coil temperature; the outdoor ambient temperature sensor 15 is used to detect the outdoor ambient temperature; the exhaust temperature sensor 16 is used to detect the exhaust temperature of the compressor; the condenser temperature sensor 17 is used to detect the temperature in the middle of the condenser; the controller 71 is configured to: when it is determined that the defrosting condition is met, control the air conditioner to enter the defrosting mode; in the defrosting mode, the controller 71 controls the opening of the electronic expansion valve 12 according to the temperature in the middle of the condenser, the indoor coil temperature, and the operating frequency of the compressor until it is determined that the condition for exiting the defrosting mode is met. Then, the compressor is controlled to reduce the frequency to the first preset frequency according to the first preset mode, and then the compressor is controlled to increase the frequency to the target operating frequency according to the second preset mode. And within the first preset time, the opening of the electronic expansion valve 12 is adjusted to the first preset opening. After that, according to the operating frequency of the compressor, the opening of the electronic expansion valve 12 in the previous cycle, the exhaust superheat in the previous cycle, the exhaust superheat in the cycle before the previous cycle, the current exhaust superheat, and the current target exhaust superheat, the opening of the electronic expansion valve 12 in the next cycle is controlled. Among them, the exhaust superheat is the difference between the exhaust temperature of the compressor and the temperature in the middle of the condenser, which improves the accuracy of defrosting, avoids false defrosting, ensures the heating capacity of the air conditioner, and at the same time makes the electronic expansion valve 12 reach the optimal opening, prevents the compressor from generating liquid hammer during defrosting, and enables the internal pressure of the air conditioner to quickly reach equilibrium.

[0097] A further embodiment of the present invention also discloses a control method for an air conditioner, which is used for the air conditioner in any of the above embodiments, as Figure 8 shown, the method includes the following steps:

[0098] Step S1: When it is determined that the defrosting condition is satisfied, control the air conditioner to enter the defrosting mode.

[0099] Step S2: In the defrosting mode, control the opening degree of the electronic expansion valve according to the temperature in the middle of the condenser, the indoor coil temperature and the operating frequency of the compressor, until it is determined that the condition for exiting the defrosting mode is satisfied, then control the compressor to reduce the frequency to the first preset frequency according to the first preset mode, and then control the compressor to increase the frequency to the target operating frequency according to the second preset mode, and within the first preset time, control the opening degree of the electronic expansion valve to be adjusted to the first preset opening degree, and then control the opening degree of the electronic expansion valve in the next cycle according to the operating frequency of the compressor, the opening degree of the electronic expansion valve in the previous cycle, the exhaust superheat degree in the previous cycle, the exhaust superheat degree in the cycle before the previous cycle, the current exhaust superheat degree and the current target exhaust superheat degree, where the exhaust superheat degree is the difference between the exhaust temperature of the compressor and the temperature in the middle of the condenser.

[0100] In an embodiment of the present invention, determining that the defrosting condition is satisfied includes: when the continuous operating time of the compressor exceeds the preset heating operating time, and the cumulative heating operating time of the compressor is greater than the defrosting interval time of this time, and any one of the following three conditions is satisfied, it is determined that the defrosting condition is satisfied; where, Condition 1: The outdoor ambient temperature is in the first preset ambient temperature range, and for a continuous second preset time, the difference between the outdoor coil temperature and the outdoor ambient temperature is less than the corresponding first preset temperature, and the maximum temperature change of the outdoor coil temperature is greater than the second preset temperature, where different first preset ambient temperature ranges correspond to a first preset temperature; Condition 2: The outdoor ambient temperature is less than the third preset temperature, and the duration reaches the third preset time, and for a continuous fourth preset time, the difference between the outdoor coil temperature and the outdoor ambient temperature reaches the fourth preset temperature, and the maximum temperature change of the outdoor coil temperature is greater than the fifth preset temperature; Condition 3: The outdoor ambient temperature when the compressor starts is less than the sixth preset temperature, and after the compressor starts for the fifth preset time, for a continuous sixth preset time, the outdoor ambient temperature is less than the seventh preset temperature, and the cumulative heating operating time of the compressor reaches the seventh preset time.

[0101] In an embodiment of the present invention, calculating the defrosting interval time of this time includes: when the defrosting time of this time is greater than the defrosting time of the previous time, the defrosting interval time of this time is the difference between the defrosting interval of the previous time and the eighth preset time; when the defrosting time of this time is not greater than the defrosting time of the previous time, the defrosting interval time of this time is the sum of the defrosting interval of the previous time and the eighth preset time.

[0102] In an embodiment of the present invention, controlling the opening degree of the electronic expansion valve according to the temperature in the middle of the condenser, the indoor coil temperature, and the operating frequency of the compressor includes performing the following formula:

[0103] P = a×F + b×(T 6 - T 5 ) + d;

[0104] Wherein, P is the opening degree of the electronic expansion valve in the defrosting mode, F is the operating frequency of the compressor, T 6 is the indoor coil temperature, T 5 is the temperature in the middle of the condenser, and a, b, and d are respectively preset parameters.

[0105] In an embodiment of the present invention, determining the condition for meeting the exit from the defrosting mode includes: when the current defrosting time is greater than the preset defrosting time, or; when the outdoor ambient temperature is within the second preset ambient temperature range and the outdoor coil temperature is greater than the corresponding eighth preset temperature for the continuous ninth preset time, it is determined that the condition for meeting the exit from the defrosting mode is satisfied; wherein, different second preset ambient temperature ranges correspond to an eighth preset temperature.

[0106] In an embodiment of the present invention, controlling the compressor to reduce the frequency to the first preset frequency according to the first preset mode includes: controlling the operating frequency of the compressor to decrease to the corresponding second preset frequency every tenth preset time until the frequency is reduced to the first preset frequency.

[0107] In an embodiment of the present invention, controlling the compressor to increase the frequency to the target operating frequency according to the second preset mode includes: judging whether the target operating frequency is greater than the third preset frequency; when it is judged that the target operating frequency is greater than the third preset frequency, controlling the operating frequency of the compressor to rise to the third preset frequency, and after the tenth preset time, controlling the operating frequency of the compressor to continue to rise to the target operating frequency; when it is judged that the target operating frequency is not greater than the third preset frequency, controlling the operating frequency of the compressor to directly rise to the target operating frequency.

[0108] In an embodiment of the present invention, controlling the opening degree of the electronic expansion valve in the next cycle according to the operating frequency of the compressor, the opening degree of the electronic expansion valve in the previous cycle, the exhaust superheat degree in the previous cycle, the exhaust superheat degree in the cycle before the previous cycle, the current exhaust superheat degree, and the current target exhaust superheat degree includes performing the following formula:

[0109] P 下 = P 上 + ΔK;

[0110] ΔK = A×D + B×(G 当 - G 目 ) + C×V;

[0111]

[0112] V = (G 当 - G 上 ) - (G 上 - G 上上 ) ;

[0113] D = (G 当 - G 上 ) ;

[0114] Wherein, P 下 is the opening degree of the electronic expansion valve in the next cycle, P 上 is the opening degree of the electronic expansion valve in the previous cycle, ΔK is the change amount of the opening degree of the electronic expansion valve, D is the exhaust superheat growth rate, G 当 is the current exhaust superheat, G 目 is the current target exhaust superheat, G 上 is the exhaust superheat in the previous cycle, G 上上 is the exhaust superheat in the cycle before the previous cycle, V is the exhaust superheat growth rate, F 1 is the operating frequency of the compressor after exiting the defrost mode, A, B, C, and M are preset parameters respectively, T is the preset number of cycles, and t is an integer between 1 and T.

[0115] In an embodiment of the present invention, before determining that the defrosting condition is satisfied, it includes: when the air conditioner changes from the power-off state to the power-on state and the outdoor ambient temperature is less than the ninth preset temperature, controlling the air conditioner to enter the heating mode, controlling the operating frequency of the compressor to be the fourth preset frequency, and controlling the outdoor fan to close. After continuing for the eleventh preset time, controlling the air conditioner to enter the defrost mode.

[0116] According to the control method of the air conditioner according to an embodiment of the present invention, when it is determined that the defrosting condition is satisfied, the air conditioner is controlled to enter the defrosting mode. In the defrosting mode, the opening degree of the electronic expansion valve is controlled according to the temperature in the middle of the condenser, the indoor coil temperature, and the operating frequency of the compressor until it is determined that the condition for exiting the defrosting mode is satisfied. Then, the compressor is controlled to reduce the frequency to a first preset frequency according to a first preset mode, and then the compressor is controlled to increase the frequency to a target operating frequency according to a second preset mode. And within a first preset time, the opening degree of the electronic expansion valve is controlled to be adjusted to a first preset opening degree. After that, the opening degree of the electronic expansion valve in the next cycle is controlled according to the operating frequency of the compressor, the opening degree of the electronic expansion valve in the previous cycle, the exhaust superheat degree in the previous cycle, the exhaust superheat degree in the cycle before the previous cycle, the current exhaust superheat degree, and the current target exhaust superheat degree. Wherein, the exhaust superheat degree is the difference between the exhaust temperature of the compressor and the temperature in the middle of the condenser, which improves the defrosting accuracy, avoids false defrosting, ensures the heating capacity of the air conditioner, and at the same time enables the electronic expansion valve to reach the optimal opening degree, prevents liquid hammer from occurring in the compressor during defrosting, and enables the internal pressure of the air conditioner to quickly reach equilibrium.

[0117] It should be noted that when the control method of the air conditioner according to the embodiment of the present invention controls the air conditioner, its specific implementation manner is similar to the specific implementation manner of the air conditioner according to the embodiment of the present invention. For details, please refer to the description of the air conditioner part. To reduce redundancy, it will not be elaborated here.

[0118] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example.

[0119] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirits of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. An air conditioner, It is characterized in that include: A refrigerant circulation loop, wherein the refrigerant performs a refrigeration cycle in a loop consisting of a compressor, a condenser, an expansion valve, and an evaporator, wherein one of the condenser and the evaporator is an outdoor heat exchanger and the other is an indoor heat exchanger; an electronic expansion valve, disposed between the condenser and the evaporator, the electronic expansion valve being used to increase the flow resistance of the refrigerant passing through the electronic expansion valve when the opening degree of the electronic expansion valve is reduced, and to reduce the flow resistance of the refrigerant passing through the electronic expansion valve when the opening degree of the electronic expansion valve is increased; Indoor coil temperature sensor, used to detect indoor coil temperature; Outdoor coil temperature sensor, used to detect outdoor coil temperature; Outdoor ambient temperature sensor, used to detect outdoor ambient temperature; An exhaust temperature sensor, used to detect the exhaust temperature of the compressor; A condenser temperature sensor, used to detect the temperature in the middle of the condenser; A controller, the controller being configured to: when it is determined that a defrost condition is met, control the air conditioner to enter a defrost mode; In the defrost mode, the controller controls the opening of the electronic expansion valve according to the temperature in the middle of the condenser, the indoor coil temperature and the operating frequency of the compressor until it is determined that the conditions for exiting the defrost mode are met. The controller then controls the compressor to reduce the frequency to the first preset frequency according to the first preset mode, and then controls the compressor to increase the frequency to the target operating frequency according to the second preset mode, and controls the opening of the electronic expansion valve to be adjusted to the first preset opening within the first preset time. Thereafter, the controller controls the opening of the electronic expansion valve in the next cycle according to the operating frequency of the compressor, the opening of the electronic expansion valve in the previous cycle, the exhaust superheat in the previous cycle, the exhaust superheat in the previous cycle, the current exhaust superheat and the current target exhaust superheat, wherein the exhaust superheat is the difference between the exhaust temperature of the compressor and the temperature in the middle of the condenser.

2. The air conditioner according to claim 1, It is characterized in that When it is determined that the defrost condition is met, the controller is specifically configured to: When the continuous operation time of the compressor exceeds the preset heating operation time, and the cumulative heating operation time of the compressor is greater than the current defrosting interval time, and any of the following three conditions is met, it is determined that the defrosting condition is met; wherein, Condition 1: the outdoor ambient temperature is within a first preset ambient temperature interval, and for a second preset time, the difference between the outdoor coil temperature and the outdoor ambient temperature is less than the corresponding first preset temperature, and the maximum temperature variation of the outdoor coil temperature is greater than the second preset temperature, wherein different first preset ambient temperature intervals correspond to one first preset temperature; Condition 2: the outdoor ambient temperature is lower than the third preset temperature and lasts for the third preset time, and for the fourth preset time, the difference between the outdoor coil temperature and the outdoor ambient temperature reaches the fourth preset temperature, and the maximum temperature variation of the outdoor coil temperature is greater than the fifth preset temperature; Condition three: the outdoor ambient temperature when the compressor is started is lower than the sixth preset temperature, and after the compressor is started for the fifth preset time, the outdoor ambient temperature is lower than the seventh preset temperature for the sixth consecutive preset time, and the accumulated heating operation time of the compressor reaches the seventh preset time.

3. The air conditioner according to claim 2, It is characterized in that When calculating the defrosting interval time this time, the controller is specifically configured as follows: When the current defrost time is greater than the previous defrost time, the current defrost interval is the difference between the previous defrost interval and the eighth preset time; When the current defrost time is not greater than the previous defrost time, the current defrost interval is the sum of the previous defrost interval and the eighth preset time.

4. The air conditioner according to claim 1, It is characterized in that When controlling the opening of the electronic expansion valve according to the temperature of the middle part of the condenser, the indoor coil temperature and the operating frequency of the compressor, the controller is specifically configured to execute the following formula: P=a×F+b×(T 6 -T 5 )+d; Wherein, P is the opening degree of the electronic expansion valve in the defrost mode, F is the operating frequency of the compressor, T 6 is the indoor coil temperature, T 5 is the temperature in the middle of the condenser, and a, b, and d are preset parameters respectively.

5. The air conditioner according to claim 1, It is characterized in that When it is determined that the condition for exiting the defrost mode is met, the controller is specifically configured to: When the current defrost time is greater than the preset defrost time, or; When the outdoor ambient temperature is in the second preset ambient temperature range and the outdoor coil temperature is greater than the corresponding eighth preset temperature for the ninth consecutive preset time, it is determined that the conditions for exiting the defrost mode are met; wherein different second preset ambient temperature ranges correspond to one eighth preset temperature.

6. The air conditioner according to claim 1, It is characterized in that When controlling the compressor to reduce the frequency to the first preset frequency according to the first preset mode, the controller is specifically configured as follows: The operating frequency of the compressor is controlled to decrease to the corresponding second preset frequency every tenth preset time until it decreases to the first preset frequency.

7. The air conditioner according to claim 1, It is characterized in that When controlling the compressor to increase the frequency to the target operating frequency according to the second preset mode, the controller is specifically configured as follows: Determining whether the target operating frequency is greater than a third preset frequency; When it is determined that the target operating frequency is greater than the third preset frequency, the operating frequency of the compressor is controlled to increase to the third preset frequency, and after a tenth preset time, the operating frequency of the compressor is controlled to continue to increase to the target operating frequency; When it is determined that the target operating frequency is not greater than the third preset frequency, the operating frequency of the compressor is controlled to directly increase to the target operating frequency.

8. The air conditioner according to claim 1, It is characterized in that When controlling the opening of the electronic expansion valve in the next cycle according to the operating frequency of the compressor, the opening of the electronic expansion valve in the previous cycle, the exhaust superheat in the previous cycle, the exhaust superheat in the previous cycle, the current exhaust superheat and the current target exhaust superheat, the controller is specifically configured to execute the following formula: P 下 =P 上 +ΔK; ΔK=A×D+B×(G 当 -G 目 )+C×V; V=(G 当 -G 上 )-(G 上 -G 上上 ); D=(G 当 -G 上 ); Among them, P 下 is the opening degree of the electronic expansion valve in the next cycle, P 上 is the opening of the electronic expansion valve in the previous cycle, ΔK is the change in the opening of the electronic expansion valve, D is the growth rate of the exhaust superheat, G 当 is the current exhaust gas superheat, G 目 is the current target exhaust superheat, G 上 is the exhaust gas superheat of the previous cycle, G 上上 is the exhaust superheat of the previous cycle, V is the exhaust superheat growth rate, F 1 After exiting the defrost mode, the operating frequency of the compressor, A, B, C, M are preset parameters respectively, T is the preset number of cycles, and t is an integer between 1 and T.

9. The air conditioner according to any one of claims 1 to 8, It is characterized in that Before determining that the defrost condition is met, the controller is further configured to: When the air conditioner changes from a power-off state to a power-on state, and the outdoor ambient temperature is lower than a ninth preset temperature, the air conditioner is controlled to enter a heating mode, the operating frequency of the compressor is controlled to be a fourth preset frequency, and the outdoor fan is controlled to be turned off. After an eleventh preset time, the air conditioner is controlled to enter the defrost mode.

10. A method for controlling an air conditioner, It is characterized in that For the air conditioner according to any one of claims 1 to 9, the method comprises the following steps: When it is determined that the defrosting condition is met, controlling the air conditioner to enter a defrosting mode; In the defrost mode, the opening of the electronic expansion valve is controlled according to the temperature in the middle of the condenser, the indoor coil temperature and the operating frequency of the compressor until it is determined that the conditions for exiting the defrost mode are met. After that, the compressor is controlled to reduce the frequency to the first preset frequency according to the first preset mode, and then the compressor is controlled to increase the frequency to the target operating frequency according to the second preset mode, and within the first preset time, the opening of the electronic expansion valve is controlled to be adjusted to the first preset opening, and then the opening of the electronic expansion valve in the next cycle is controlled according to the operating frequency of the compressor, the opening of the electronic expansion valve in the previous cycle, the exhaust superheat in the previous cycle, the exhaust superheat in the previous cycle, the current exhaust superheat and the current target exhaust superheat, wherein the exhaust superheat is the difference between the exhaust temperature of the compressor and the temperature in the middle of the condenser.

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