Air conditioner and controlling method thereof

Abstract

The disclosed air conditioner comprises: an indoor unit including an indoor heat exchanger; an outdoor unit including a compressor that supplies refrigerant to the indoor heat exchanger; an indoor heat exchanger temperature sensor that detects the temperature of the indoor heat exchanger; an indoor humidity sensor that detects indoor humidity; an indoor temperature sensor that detects the indoor temperature; and a control unit that determines whether to perform a comfortable operation to maintain the temperature of the indoor heat exchanger below the dew point temperature based on the indoor humidity during dehumidification operation, and adjusts the frequency of the compressor based on the temperature of the indoor heat exchanger and the dew point temperature during the comfortable operation.

Description

Technology Field

[0001] The disclosed invention relates to an air conditioner capable of maintaining indoor humidity and indoor temperature at a constant level during dehumidification operation, and a method for controlling the same. Background Technology

[0002] An air conditioner is a device that cools or heats air by utilizing the heat transfer generated from the evaporation and condensation of a refrigerant, and conditioneds the air in an indoor space by discharging the cooled or heated air. During cooling or heating operation, the air conditioner circulates the refrigerant through a compressor, an indoor heat exchanger, and an outdoor heat exchanger, and can cool or heat the indoor space by discharging the air, which has undergone heat exchange in the indoor heat exchanger, into the indoor space.

[0003] Generally, the dehumidification operation of an air conditioner is performed to lower indoor humidity by removing moisture contained in the indoor air. Just as indoor air is cooled by cooling operation, indoor air can also be cooled by dehumidification operation. In typical dehumidification operation, the compressor is controlled to repeatedly turn on and off in response to changes in indoor temperature. However, as the compressor repeatedly turns on and off, the fluctuation range of indoor temperature and indoor humidity increases. This may cause discomfort to the user. The problem to be solved

[0004] The disclosed invention provides an air conditioner and a control method thereof that can reduce fluctuations in indoor temperature and indoor humidity by performing comfortable operation by appropriately adjusting the frequency of the compressor without on-off control of the compressor during dehumidification operation. means of solving the problem

[0005] An air conditioner according to one embodiment comprises: an indoor unit including an indoor heat exchanger; an outdoor unit including a compressor that supplies refrigerant to the indoor heat exchanger; an indoor heat exchanger temperature sensor that detects the temperature of the indoor heat exchanger; an indoor humidity sensor that detects indoor humidity; an indoor temperature sensor that detects the indoor temperature; and a control unit that determines whether to perform a comfortable operation to maintain the temperature of the indoor heat exchanger below the dew point temperature based on the indoor humidity during a dehumidification operation, and adjusts the frequency of the compressor based on the temperature of the indoor heat exchanger and the dew point temperature during the comfortable operation.

[0006] The control unit can enter the comfortable operation based on the fact that, during a predetermined first time in the dehumidification operation, the indoor temperature is maintained below a predetermined first threshold temperature and a desired temperature set by the user, and the indoor humidity is maintained below a predetermined threshold humidity.

[0007] The control unit may stop the comfortable operation based on the fact that during a predetermined second time in the comfortable operation, the indoor temperature is maintained at or above a second critical temperature which is higher than the first critical temperature, or the indoor humidity is maintained at or above the critical humidity.

[0008] The control unit can calculate the dew point temperature from the indoor humidity and the indoor temperature during comfortable operation, and determine to increase or decrease the frequency of the compressor based on the difference between the temperature of the indoor heat exchanger and the dew point temperature and the change in temperature of the indoor heat exchanger.

[0009] The above control unit can determine an increase in the frequency of the compressor or a decrease in the frequency of the compressor corresponding to the difference between the temperature of the indoor heat exchanger and the dew point temperature and the change in the temperature of the indoor heat exchanger from a fuzzy table stored in memory.

[0010] The control unit may increase the rotational speed of the outdoor fan included in the outdoor unit and increase the opening of the expansion valve included in the indoor unit in response to an increase in the frequency of the compressor, or decrease the rotational speed of the outdoor fan and decrease the opening of the expansion valve in response to a decrease in the frequency of the compressor.

[0011] The control unit can adjust the first rotational speed of the compressor in the comfort operation to be slower than the second rotational speed of the compressor in the dehumidification operation, and adjust the third rotational speed of the outdoor fan included in the outdoor unit in the comfort operation to be slower than the fourth rotational speed of the outdoor fan in the dehumidification operation.

[0012] A control method for an air conditioner according to one embodiment comprises: detecting indoor humidity using an indoor humidity sensor included in the indoor unit during dehumidification operation; detecting indoor temperature using an indoor temperature sensor included in the indoor unit during dehumidification operation; determining whether to perform a comfortable operation to maintain the temperature of the indoor heat exchanger below the dew point temperature based on the indoor humidity and the indoor humidity during dehumidification operation; and adjusting the frequency of the compressor based on the temperature of the indoor heat exchanger and the dew point temperature during the comfortable operation.

[0013] The above comfortable operation can be performed based on the fact that, during a predetermined first time in the above dehumidification operation, the indoor temperature is maintained below a predetermined first critical temperature and a desired temperature set by the user, and the indoor humidity is maintained below a predetermined critical humidity.

[0014] The control method of the air conditioner described above may further include stopping the comfortable operation based on the fact that during a predetermined second time in the comfortable operation, the indoor temperature is maintained at or above a second critical temperature which is higher than the first critical temperature, or the indoor humidity is maintained at or above the critical humidity.

[0015] Adjusting the frequency of the compressor may include calculating the dew point temperature from the indoor humidity and the indoor humidity; and determining an increase in the frequency of the compressor or a decrease in the frequency of the compressor based on the difference between the temperature of the indoor heat exchanger and the dew point temperature and the change in temperature of the indoor heat exchanger.

[0016] Adjusting the frequency of the compressor may include determining an increase value or a decrease value of the compressor's frequency corresponding to the difference between the temperature of the indoor heat exchanger and the dew point temperature and the change value of the temperature of the indoor heat exchanger from a fuzzy table stored in memory.

[0017] The control method of the air conditioner may further include increasing the rotational speed of the outdoor fan included in the outdoor unit and increasing the opening of the expansion valve included in the indoor unit in response to an increase in the frequency of the compressor; or decreasing the rotational speed of the outdoor fan and decreasing the opening of the expansion valve in response to a decrease in the frequency of the compressor.

[0018] In the above comfortable operation, the first rotational speed of the compressor is adjusted to be slower than the second rotational speed of the compressor in the above dehumidification operation, and in the above comfortable operation, the third rotational speed of the outdoor fan included in the outdoor unit can be adjusted to be slower than the fourth rotational speed of the outdoor fan in the above dehumidification operation. Effects of the invention

[0019] The disclosed air conditioner and its control method can reduce fluctuations in indoor temperature and indoor humidity by performing comfortable operation that appropriately adjusts the compressor frequency without on-off control of the compressor based on predetermined conditions during dehumidification operation. As fluctuations in indoor temperature and indoor humidity are reduced, power consumption efficiency can be improved, and a more comfortable indoor environment can be provided to the user. Brief explanation of the drawing

[0020] FIG. 1 is an external view of an air conditioner according to one embodiment. FIG. 2 shows the flow of refrigerant when an air conditioner according to one embodiment performs heating operation or cooling operation. FIG. 3 is a block diagram illustrating the control configuration of an outdoor unit according to one embodiment. FIG. 4 is a block diagram illustrating the control configuration of an indoor unit according to one embodiment. FIG. 5 is a flowchart illustrating a control method for an air conditioner according to one embodiment. Figure 6 is a flowchart that explains in more detail the control method of the air conditioner described in Figure 5. FIG. 7 illustrates a fuzzy table according to one embodiment. Figure 8 is a graph showing changes in indoor humidity, indoor temperature, and compressor frequency during normal dehumidification operation. Figure 9 is a graph showing changes in indoor humidity, indoor temperature, and compressor frequency when comfortable operation is performed during dehumidification operation. Specific details for implementing the invention

[0021] The embodiments described in this specification and the configurations illustrated in the drawings are merely preferred examples of the disclosed invention, and various modifications that may replace the embodiments and drawings of this specification may exist at the time of filing this application.

[0022] Throughout this specification, when a part is described as being "connected" to another part, this includes not only cases where they are directly connected but also cases where they are indirectly connected, and indirect connection includes being connected via a wireless communication network.

[0023] Furthermore, the terms used in this specification are for describing embodiments and are not intended to limit or / or restrict the disclosed invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprising" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and do not preclude the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0024] Additionally, terms including ordinal numbers, such as "first," "second," etc., used in this specification may be used to describe various components, but said components are not limited by said terms, and said terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component.

[0025] In addition, terms such as "~part," "~unit," "~block," "~part," and "~module" may refer to a unit that processes at least one function or operation. For example, the above terms may refer to at least one piece of hardware such as an FPGA (field-programmable gate array) or ASIC (application specific integrated circuit), at least one piece of software stored in memory, or at least one process processed by a processor.

[0026] The symbols attached to each step are used to identify each step and do not indicate the order of the steps relative to one another; the steps may be performed differently from the specified order unless a specific order is clearly indicated in the context.

[0027] Hereinafter, embodiments according to the present invention will be described in detail with reference to the attached drawings.

[0028] FIG. 1 is an external view of an air conditioner according to one embodiment.

[0029] Referring to FIG. 1, the air conditioner (1) includes an outdoor unit (1a) that performs heat exchange between outdoor air and a refrigerant in an outdoor space, and an indoor unit (1b) that performs heat exchange between indoor air and a refrigerant in an indoor space. The outdoor unit (1a) may be located outside the air conditioner space, and the indoor unit (1b) may be located inside the air conditioner space. The air conditioner space refers to a space that is cooled or heated by the air conditioner (1). For example, the outdoor unit (1a) may be placed outside a building, and the indoor unit (1b) may be placed inside a space separated from the outside by a wall, such as a living room or an office.

[0030] The outdoor unit (1a) and the indoor unit (1b) are connected via external pipes (P1, P2). The refrigerant can circulate through the outdoor unit (1a), the external pipes (P1, P2), and the indoor unit (1b). One end of the external pipes (P1, P2) can be connected to a pipe valve provided on one side of the outdoor unit (1a). Additionally, the external pipes (P1, P2) can be connected to refrigerant pipes provided inside the outdoor unit (1a) and the indoor unit (1b).

[0031] An outdoor fan (150) may be provided within the housing of the outdoor unit (1a). When the outdoor fan (150) operates, air may be discharged to the outside of the outdoor unit (1a) through the discharge port of the housing. A fan guard (22) may be provided at the discharge port to protect the outdoor fan (150). The fan guard (22) may cover the discharge port and may have a grille or mesh shape.

[0032] The indoor unit (1b) may include a body case (201) and a front panel (202). Additionally, the indoor unit (1b) may include at least one discharge port (205) of the front panel (202) and at least one door (204) capable of opening and closing the discharge port (205). For example, the door (204) may include a first door (204a), a second door (204b), and a third door (204c). The discharge port (205) may include a first discharge port (205a), a second discharge port (205b), and a third discharge port (205c). The discharge port (205) and the door (204) may be provided in the upper area of ​​the front panel (202).

[0033] The front panel (202) may include a plurality of holes (202h) distinct from the discharge port (205). The plurality of holes (202h) may be provided in an area of ​​the front panel (202) where the discharge port (205) is not formed. The size of each of the plurality of holes (202h) is smaller than the size of the discharge port (205).

[0034] The discharge port (205) is provided so that air heat-exchanged by the indoor heat exchanger (230) can be directly discharged to the outside. That is, the discharge port (205) can be provided to be exposed to the outside of the indoor unit (1b). The door (204) can open or close the discharge port (205). When the discharge port (205) is opened by moving the door (204), heat-exchanged air can be discharged through the discharge port (205).

[0035] For example, the first door (204a) may open the first discharge port (205a), the second door (204b) may open the second discharge port (205b), and the third door (204c) may close the third discharge port (205c). In this case, heat-exchanged air may be discharged through the first discharge port (205a) and the second discharge port (205b), and heat-exchanged air may not be discharged through the third discharge port (205c).

[0036] The door (204) and the discharge port (205) may be provided in equal numbers and arranged to correspond one-to-one. The door (204) may have a shape corresponding to the shape of the discharge port (205). For example, the discharge port (205) and the door (204) may be circular. The door (204) may move between an open position that opens the discharge port (205) and a closed position that closes the discharge port (205). The door (204) may move between the open position and the closed position in the forward and backward directions. The door (204) may be moved by a door actuator (not shown).

[0037] An indoor fan (250) provided inside the indoor unit (1b) may be placed inside the body case (201) to correspond to the discharge port (205). The indoor fan (250) may be provided in a number corresponding to the number of discharge ports (205). The indoor fan (250) includes a fan motor and may rotate using power generated by the fan motor. If there are multiple indoor fans (250), each indoor fan (250) may be controlled to operate at the same rotational speed or different rotational speeds.

[0038] An air inlet (203) may be provided at the rear of the body case (201). Air introduced through the air inlet (203) is heat-exchanged in an indoor heat exchanger (230), and the heat-exchanged air may be discharged to the outside of the indoor unit (1b) (i.e., indoor space) through the discharge port (205). Additionally, the heat-exchanged air may be discharged to the outside of the indoor unit (1b) (indoor space) through a plurality of holes (202h) of the front panel (202).

[0039] When the door (204) opens the discharge port (205), the heat-exchanged air can be discharged into the indoor space through the discharge port (205) and the plurality of holes (202h) of the front panel (202). When the door (204) closes the discharge port (205), the heat-exchanged air can be discharged to the outside of the indoor unit (1b) through the plurality of holes (202h) of the front panel (202).

[0040] When the discharge port (205) is closed by the door (204), the rotational speed of the indoor fan (250) can be controlled to be relatively low. The airflow velocity of the air discharged through the plurality of holes (202h) when the discharge port (205) is closed can be slower than the airflow velocity of the air discharged through the open discharge port (205). In this way, the indoor unit (1b) can control the door (204) to open or close the discharge port (205) and change the discharge path of the air introduced through the air inlet (203).

[0041] Although the air conditioner (1) has been described as comprising one outdoor unit (1a) and one indoor unit (1b), it may also comprise multiple outdoor units (1a) and multiple indoor units (1b). For example, multiple indoor units (1b) may be connected to one outdoor unit (1a). Furthermore, the shape of the indoor unit (1b) is not limited to that described. Any type of indoor unit (1b) may be applied as long as it is an indoor unit (1b) that is installed in an indoor space and capable of cooling or heating the indoor space.

[0042] FIG. 2 shows the flow of refrigerant when an air conditioner according to one embodiment performs heating operation or cooling operation.

[0043] Referring to FIG. 2, the air conditioner (1) includes a refrigerant flow path for circulating refrigerant between an indoor unit (1b) and an outdoor unit (1a). The refrigerant circulates between the indoor unit (1b) and the outdoor unit (1a) along the refrigerant flow path and can absorb or release heat through a change of state (e.g., a change of state from gas to liquid, a change of state from liquid to gas).

[0044] The air conditioner (1) may include a liquid pipe (P1) that connects the outdoor unit (1a) and the indoor unit (1b) and serves as a passage for liquid refrigerant to flow, and a gas pipe (P2) that serves as a passage for gaseous refrigerant to flow. The liquid pipe (P1) and the gas pipe (P2) may extend into the outdoor unit (1a) and the indoor unit (1b).

[0045] During cooling operation, the refrigerant can release heat in the outdoor heat exchanger (130) and absorb heat in the indoor heat exchanger (230). During cooling operation, the refrigerant compressed in the compressor (110) is first supplied to the outdoor heat exchanger (130) via the four-way valve (120) and can be supplied to the indoor heat exchanger (230) via the expansion valve (220). During cooling operation, the outdoor heat exchanger (130) operates as a condenser that condenses the refrigerant, and the indoor heat exchanger (230) operates as an evaporator that evaporates the refrigerant.

[0046] During cooling or dehumidification operation, the high-temperature, high-pressure gaseous refrigerant discharged from the compressor (110) moves to the outdoor heat exchanger (130). The liquid or near-liquid refrigerant condensed in the outdoor heat exchanger (130) is expanded and depressurized at the expansion valve (220). The two-phase refrigerant that passes through the expansion valve (220) moves to the indoor heat exchanger (230). The refrigerant introduced into the indoor heat exchanger (230) evaporates by exchanging heat with the surrounding air. Consequently, the temperature of the air passing through the indoor heat exchanger (230) decreases, and cooled air is discharged to the outside of the indoor unit (1b). Additionally, since the moisture contained in the air passing through the indoor heat exchanger (230) condenses, air with moisture removed can be discharged into the indoor space.

[0047] During dehumidification operation, the frequency of the compressor (110) is controlled to be relatively low. Therefore, the temperature of the air discharged from the indoor unit (1b) during dehumidification operation may be higher than the temperature of the air discharged during cooling operation.

[0048] During heating operation, the refrigerant can release heat in the indoor heat exchanger (230) and absorb heat in the outdoor heat exchanger (130). That is, during heating operation, the refrigerant compressed by the compressor (110) can be supplied first to the indoor heat exchanger (230) via the four-way valve (120) and then to the outdoor heat exchanger (130). In this case, the indoor heat exchanger (230) operates as a condenser that condenses the refrigerant, and the outdoor heat exchanger (130) operates as an evaporator that evaporates the refrigerant.

[0049] During heating operation, the high-temperature, high-pressure gaseous refrigerant discharged from the compressor (110) moves to the indoor heat exchanger (230). The high-temperature, high-pressure gaseous refrigerant passing through the indoor heat exchanger (230) exchanges heat with the low-temperature, dry air. As the refrigerant condenses into a liquid or near-liquid state, it releases heat, and as the air absorbs the heat, warm air is discharged to the outside of the indoor unit (1b).

[0050] The outdoor unit (1a) includes a compressor (110) that compresses the refrigerant, an outdoor heat exchanger (130) that performs heat exchange between the outdoor air and the refrigerant, a four-way valve (120) that guides the refrigerant compressed by the compressor (110) to the outdoor heat exchanger (130) or the indoor heat exchanger (230) based on cooling operation, dehumidification operation, or heating operation, and an accumulator (160) that prevents unevaporated liquid refrigerant from flowing into the compressor (110).

[0051] The compressor (110) can operate by receiving electrical energy from an external power source. The compressor (110) includes a compressor motor (not shown) and uses the rotational force of the compressor motor to compress low-pressure gaseous refrigerant to high pressure. The frequency of the compressor (110) can be changed to correspond to the capacity required by the indoor unit (1b). The compressor (110) may be an inverter air compressor, a positive displacement compressor, or a dynamic compressor, and various types of compressors that the designer can consider may be used.

[0052] The four-way valve (120) can change the flow direction of the high-temperature, high-pressure gaseous refrigerant discharged from the compressor (110). The four-way valve (120) is controlled to guide the refrigerant compressed by the compressor (110) to the outdoor heat exchanger (130) during cooling operation or dehumidification operation. The four-way valve (120) is controlled to guide the refrigerant compressed by the compressor (110) to the indoor unit (1b) during heating operation.

[0053] The outdoor heat exchanger (130) acts as a condenser that condenses the refrigerant compressed by the compressor (110) during cooling or dehumidification operation. The outdoor heat exchanger (130) acts as an evaporator that evaporates the refrigerant depressurized in the indoor unit (1b) during heating operation. The outdoor heat exchanger (130) may include outdoor heat exchanger cooling fins (not shown) to increase the surface area in contact with the outdoor air and the outdoor heat exchanger refrigerant pipe (not shown) through which the refrigerant passes. If the surface area in contact with the outdoor air and the outdoor heat exchanger refrigerant pipe (not shown) is increased, the heat exchange efficiency between the refrigerant and the outdoor air can be improved.

[0054] An outdoor fan (150) is provided around an outdoor heat exchanger (130) to allow outdoor air to flow to the outdoor heat exchanger (130). The outdoor fan (150) can blow outdoor air before heat exchange to the outdoor heat exchanger (130) and simultaneously blow the heat-exchanged air to the outside. By releasing the air around the outdoor heat exchanger (130) to the outside, the outdoor fan (150) can disperse the heat released by the liquefaction of the refrigerant in the outdoor heat exchanger (130).

[0055] The accumulator (160) can store liquid refrigerant and vaporize the stored liquid refrigerant. The accumulator (160) can prevent liquid refrigerant from flowing into the compressor (110). However, if the amount of refrigerant circulation is excessive, the vaporization of the liquid refrigerant by the accumulator (160) may not be properly performed. In this case, liquid refrigerant may flow into the compressor (110), and damage to the compressor (110) may occur.

[0056] The outdoor unit (1a) may include an outdoor temperature sensor (171) for detecting the outdoor temperature. An outdoor heat exchanger temperature sensor (172) for detecting the temperature of the outdoor heat exchanger (130) may be provided on at least one side of the outdoor heat exchanger (130). The outdoor temperature sensor (171) and the outdoor heat exchanger temperature sensor (172) may be implemented as at least one of a bimetal thermometer, a thermistor thermometer, or an infrared thermometer.

[0057] Based on a cooling or dehumidification operation in which refrigerant flows from the compressor (110) to the outdoor heat exchanger (130), the outdoor heat exchanger temperature sensor (172) may be positioned at the outlet side of the outdoor heat exchanger (130) from which the refrigerant comes out. Therefore, the outdoor heat exchanger temperature sensor (172) may be referred to as the 'outdoor heat exchanger outlet temperature sensor'. Although not illustrated, a temperature sensor (not shown) may also be provided at the inlet side of the outdoor heat exchanger (130), and this may be referred to as the 'outdoor heat exchanger inlet temperature sensor'. In other words, a temperature sensor may be provided at each of the inlet and outlet of the outdoor heat exchanger (130). The outdoor heat exchanger temperature sensor (172) may be installed around the inlet and / or outlet of the outdoor heat exchanger (130), or installed to contact the refrigerant pipe connected to the inlet and / or outlet of the outdoor heat exchanger (130).

[0058] In heating operation, the circulation direction of the refrigerant is reversed, so the inlet of the outdoor heat exchanger (130) into which the refrigerant enters and the outlet of the outdoor heat exchanger (130) into which the refrigerant exits can be defined in reverse. However, for the convenience of explanation, the inlet and outlet of the outdoor heat exchanger (130) can be described based on the cooling operation.

[0059] A compressor outlet temperature sensor (173) may be provided at the outlet of the compressor (110). The compressor outlet temperature sensor (173) can detect the discharge temperature of the refrigerant discharged from the compressor (110). The discharge temperature of the refrigerant discharged from the compressor (110) may be referred to as the compressor discharge temperature or the compressor outlet temperature.

[0060] The indoor unit (1b) may include an expansion valve (220), an indoor heat exchanger (230), and an indoor fan (250). The indoor heat exchanger (230) performs heat exchange between indoor air and refrigerant. The indoor fan (250) can flow indoor air to the indoor heat exchanger (230). Multiple indoor fans (250) may be provided.

[0061] The expansion valve (220) can expand the high-temperature, high-pressure liquid refrigerant to discharge a low-temperature, low-pressure refrigerant mixed with gas and liquid. The expansion valve (220) can also regulate the amount of refrigerant supplied to the indoor heat exchanger (230). The expansion valve (220) reduces the pressure of the refrigerant using a throttling action. Throttling action means that when the refrigerant passes through a narrow path, the pressure decreases without heat exchange with the outside.

[0062] The expansion valve (220) may be an electronic expansion valve (EEV) capable of controlling the opening. The expansion valve (220) may be, for example, a thermoelectric electronic expansion valve utilizing the deformation of a bimetal, a thermal electronic expansion valve utilizing volume expansion by heating of a sealed wax, a pulse width modulation type electronic expansion valve that opens and closes a solenoid valve by a pulse signal, or a stem motor type electronic expansion valve that opens and closes the valve using a motor.

[0063] Although the expansion valve (220) is exemplified as being included in the indoor unit (1b), the expansion valve (220) may also be included in the outdoor unit (1a). Additionally, the expansion valve (220) may be provided in both the outdoor unit (1a) and the indoor unit (1b). That is, the expansion valve (220) may be provided in a liquid pipe (P1), which is a pipe forming a refrigerant flow path between the outdoor heat exchanger (130) and the indoor heat exchanger (230).

[0064] The indoor heat exchanger (230) acts as an evaporator that evaporates low-pressure liquid refrigerant during cooling or dehumidification operation. The indoor heat exchanger (230) acts as a condenser that condenses high-pressure gaseous refrigerant during heating operation. Similar to the outdoor heat exchanger (130) of the outdoor unit (1a), the indoor heat exchanger (230) includes an indoor heat exchanger refrigerant pipe (not shown) through which the refrigerant passes, and indoor heat exchanger cooling fins (not shown) to improve the heat exchange efficiency between the refrigerant and the indoor air.

[0065] An indoor fan (250) is provided around an indoor heat exchanger (230) to blow indoor air to the indoor heat exchanger (230). The indoor heat exchanger (230) can perform heat exchange with the indoor air. The indoor fan (250) can blow indoor air before heat exchange to the indoor heat exchanger (230) and at the same time blow the heat-exchanged air into the indoor space.

[0066] An indoor heat exchanger (230) may be provided with an indoor heat exchanger temperature sensor (211) for detecting the temperature of the indoor heat exchanger (230). The indoor heat exchanger temperature sensor (211) may be placed on the outer surface of the indoor heat exchanger (230) and / or at a location adjacent to the indoor heat exchanger (230). The temperature of the indoor heat exchanger (230) may represent the temperature of the air being heat-exchanged with the indoor heat exchanger (230).

[0067] Additionally, an indoor temperature sensor (213) for detecting the indoor temperature may be provided inside the indoor unit (1b). The indoor temperature sensor (213) can detect the temperature of the indoor air sucked in through the air inlet (203) located at the rear of the body case (201) of the indoor unit (1b). The indoor heat exchanger temperature sensor (211) and the indoor temperature sensor (213) may be implemented as at least one of a bimetal thermometer, a thermistor thermometer, or an infrared thermometer. In addition, the air conditioner (1) may include various temperature sensors.

[0068] The indoor humidity sensor (212) can detect indoor humidity. Indoor humidity can be expressed as relative humidity. It can detect the humidity of indoor air sucked in through the air inlet (203) located at the rear of the body case (201) of the indoor unit (1b). The indoor humidity sensor (212) can transmit an electrical signal corresponding to the detected indoor humidity to the second control unit (270) of the indoor unit (1b).

[0069] The indoor temperature sensor (213) and the indoor humidity sensor (212) may be placed inside the body case (201), but are not limited thereto. The indoor temperature sensor (213) and the indoor humidity sensor (212) may also be placed outside the body case (201).

[0070] FIG. 3 is a block diagram illustrating the control configuration of an outdoor unit according to one embodiment.

[0071] Referring to FIG. 3, the outdoor unit (1a) of the air conditioner (1) may include a compressor (110), a four-way valve (120), an outdoor fan (150), an outdoor temperature sensor (171), an outdoor heat exchanger temperature sensor (172), a compressor outlet temperature sensor (173), a first communication interface (180), and a first control unit (190). The first control unit (190) may include a first memory (192) and a first processor (191).

[0072] The first control unit (190) can be electrically connected to the components of the outdoor unit (1a) and can control the operation of each component. For example, the first control unit (190) can adjust the frequency of the compressor (110) and control the four-way valve (120) to switch the refrigerant circulation direction. The first control unit (190) can adjust the rotational speed of the outdoor fan (150). The rotational speed of the outdoor fan (150) can be adjusted according to the outdoor temperature. In addition, the first control unit (190) can generate a control signal to adjust the opening degree of the expansion valve (220) of the indoor unit (1b).

[0073] Under the control of the first control unit (190), refrigerant may circulate along a refrigerant circulation circuit comprising a compressor (110), a four-way valve (120), an outdoor heat exchanger (130), an expansion valve (220), and an indoor heat exchanger (230). The compressor (110) may compress gaseous refrigerant and discharge high-temperature / high-pressure gaseous refrigerant. Additionally, the compressor (110) may not operate during blower operation when cooling and heating are not required.

[0074] The four-way valve (120) can switch the circulation direction of the refrigerant discharged from the compressor (110) under the control of the first control unit (190). The four-way valve (120) guides the refrigerant compressed by the compressor (110) to the outdoor heat exchanger (130) during cooling operation, and guides the refrigerant compressed by the compressor (110) to the indoor heat exchanger (230) during heating operation.

[0075] The outdoor temperature sensor (171) can transmit an electrical signal corresponding to the detected outdoor temperature to the first control unit (190). The outdoor heat exchanger temperature sensor (172) can transmit an electrical signal corresponding to the detected inlet temperature and / or outlet temperature of the outdoor heat exchanger to the first control unit (190). The compressor outlet temperature sensor (173) can transmit an electrical signal corresponding to the compressor discharge temperature to the first control unit (190).

[0076] The first communication interface (180) can communicate with the indoor unit (1b). The first communication interface (180) of the outdoor unit (1a) can transmit a control signal transmitted from the first control unit (190) to the indoor unit (1b), or transmit a control signal transmitted from the indoor unit (1b) to the first control unit (190). In other words, the outdoor unit (1a) and the indoor unit (1b) can perform bidirectional communication. The outdoor unit (1a) and the indoor unit (1b) can transmit and receive various signals during operation.

[0077] The first memory (192) can store / record various information required for the operation of the air conditioner (1). The first memory (192) can store instructions, applications, data, and / or programs required for the operation of the air conditioner (1). For example, the first memory (192) can store programs for cooling operation, heating operation, and defrosting operation of the air conditioner (1).

[0078] The first memory (192) may include volatile memory such as S-RAM (Static Random Access Memory, S-RAM) and D-RAM (Dynamic Random Access Memory) for temporarily storing data. Additionally, the first memory (192) may include non-volatile memory such as ROM (Read Only Memory), EPROM (Erasable Programmable Read Only Memory), and EEPROM (Electrically Erasable Programmable Read Only Memory) for long-term data storage.

[0079] The first processor (191) can generate a control signal to control the operation of the air conditioner (1) based on instructions, applications, data, and / or programs stored in the first memory (192). The first processor (191) may be hardware and may include logic circuits and arithmetic circuits. The first processor (191) may process data according to programs and / or instructions provided from the first memory (192) and generate a control signal according to the processing result. The first memory (192) and the first processor (191) may be implemented as a single control circuit or as multiple circuits.

[0080] Some of the components of the illustrated outdoor unit (1a) may be omitted, or other components may be added in addition to the components of the illustrated outdoor unit (1a). For example, the outdoor unit (1a) may further include a control panel. The control panel may be provided in the cabinet (10) of the outdoor unit (1a). The control panel may receive user input related to the operation of the air conditioner (1) and may output information regarding the operation of the air conditioner (1). The control panel may transmit an electrical signal (voltage or current) corresponding to the user input to the first control unit (190). The first control unit (190) may control the operation of the air conditioner (1) based on the electrical signal transmitted from the control panel. The control panel may include buttons and a display.

[0081] FIG. 4 is a block diagram illustrating the control configuration of an indoor unit according to one embodiment.

[0082] Referring to FIG. 4, the indoor unit (1b) of the air conditioner (1) may include an expansion valve (220), an indoor fan (250), an indoor heat exchanger temperature sensor (211), an indoor humidity sensor (212), an indoor temperature sensor (213), a second communication interface (260), and a second control unit (270). Additionally, the indoor unit (1b) may include a user interface (280).

[0083] The second control unit (270) may include a second memory (272) and a second processor (271). The second control unit (270) of the indoor unit (1b) may be electrically connected to the components of the indoor unit (1b) and may control the operation of each component.

[0084] The indoor heat exchanger temperature sensor (211) can transmit an electrical signal corresponding to the detected temperature of the indoor heat exchanger (230) to the second processor (271). The indoor humidity sensor (212) can transmit an electrical signal corresponding to the detected indoor humidity to the second processor (271). The indoor temperature sensor (213) can transmit an electrical signal corresponding to the detected indoor temperature to the second processor (271).

[0085] The expansion valve (220) can reduce the pressure of the refrigerant. Additionally, the expansion valve (220) can regulate the amount of refrigerant supplied so that sufficient heat exchange occurs in the outdoor heat exchanger (130) or the indoor heat exchanger (230). The expansion valve (220) reduces the pressure of the refrigerant by utilizing the throttling action of the refrigerant, which causes the pressure to decrease as the refrigerant passes through a narrow path.

[0086] The second communication interface (260) can communicate with the outdoor unit (1a). The second communication interface (260) of the indoor unit (1b) can transmit a control signal transmitted from the second control unit (270) to the outdoor unit (1a), or transmit a control signal transmitted from the outdoor unit (200) to the second control unit (270). For example, a control signal for adjusting the opening of the expansion valve (220) can be transmitted from the outdoor unit (1a) to the indoor unit (1b). The second control unit (270) can adjust the opening of the expansion valve (220) based on a signal transmitted from the first control unit (190) of the outdoor unit (1a).

[0087] Additionally, the second communication interface (260) can communicate with an access point (AP) (not shown) separately provided in the air conditioning space and can be connected to a network through the access point. The second communication interface (260) can communicate with a user terminal device (e.g., a smartphone) through the access point. The second communication interface (260) can receive information from a user terminal device connected to the access point and can transmit the information from the user terminal device to the second control unit (270). Through this, the user can remotely control the air conditioner (1).

[0088] The second memory (272) can store / record various information required for the operation of the air conditioner (1). The second memory (272) can store instructions, applications, data, and / or programs required for the operation of the air conditioner (1). For example, the second memory (272) can store programs for cooling operation, heating operation, and defrosting operation of the air conditioner (1). The second memory (272) may include volatile memory and / or non-volatile memory, similar to the first memory (192).

[0089] The second processor (271) can generate a control signal to control the operation of the air conditioner (1) based on instructions, applications, data, and / or programs stored in the second memory (272). The second processor (271) may include logic circuits and arithmetic circuits as hardware. The second processor (271) can process data according to programs and / or instructions provided from the second memory (272) and generate a control signal according to the processing result. The second memory (272) and the second processor (271) may be implemented as a single control circuit or as multiple circuits.

[0090] A user interface (280) may be provided in at least one of the body case (201) or door (204) of the indoor unit (1b). The user interface (280) may receive user input related to the operation of the air conditioner (1) and may output information regarding the operation of the air conditioner (1). The user interface (280) may transmit an electrical signal (voltage or current) corresponding to the user input to a second control unit (270). The second control unit (270) may control the operation of the air conditioner (1) based on the electrical signal transmitted from the user interface (280).

[0091] The user interface (280) may include a plurality of buttons. For example, the plurality of buttons may include an operation mode button for selecting an operation mode such as cooling operation, heating operation, blower operation, defrosting operation, and dehumidification operation, a temperature button for setting a target temperature of an indoor space (air conditioning space), a wind direction button for setting the direction of the wind, and / or a wind volume button for setting the wind intensity (rotation speed of the indoor fan).

[0092] Additionally, the user interface (280) may include a display. The display may display information entered by the user or information provided to the user on various screens. For example, information such as a selected driving mode, wind direction, airflow, and temperature may be displayed as at least one of an image or text.

[0093] Some of the components of the illustrated indoor unit (1b) may be omitted, or other components may be added in addition to the components of the illustrated indoor unit (1b). For example, the indoor unit (1b) may further include a control panel. The control panel can receive user input related to the operation of the air conditioner (1) and can output information regarding the operation of the air conditioner (1).

[0094] As described in FIGS. 3 and 4, the air conditioner (1) may include at least one control unit (190, 270). Although it has been described that a control unit is provided in each of the outdoor unit (1a) and the indoor unit (1b), an integrated control unit capable of controlling both the outdoor unit (1a) and the indoor unit (1b) may be provided. Hereinafter, it is described that the control of the air conditioner (1) is performed by the first control unit (190) of the outdoor unit (1a).

[0095] The disclosed air conditioner (1) can perform a dehumidification operation. The dehumidification operation can be performed according to the selection of an operation mode input through the user interface (280) of the indoor unit (1b). Generally, the dehumidification operation is performed to lower indoor humidity by removing moisture contained in the indoor air. The indoor air can also be cooled by the dehumidification operation.

[0096] Since the primary purpose of the dehumidification operation is not cooling, the frequency of the compressor (110) in the dehumidification operation can be controlled to be relatively lower than the frequency of the compressor (110) in the cooling operation. Additionally, the rotational speed of the compressor (110) in the dehumidification operation can be adjusted to be slower than the rotational speed of the compressor (110) in the cooling operation. As the frequency of the compressor (110) decreases, the rotational speed of the compressor (110) can also be slowed down. The rotational speed of the outdoor fan (150) in the dehumidification operation can also be adjusted to be slower than the rotational speed of the outdoor fan (150) in the cooling operation.

[0097] In general dehumidification operation, the compressor (110) can be controlled to repeatedly turn on and off. This is to maintain the indoor temperature and indoor humidity within a certain range. However, due to the turning on and off of the compressor (110), the fluctuation range of the indoor temperature and the fluctuation range of the indoor humidity increase. For example, if the indoor temperature drops by a predetermined offset value (e.g., 2°C) below the desired temperature set by the user, the compressor (110) turns off, and if the indoor temperature rises by an offset value (e.g., 2°C) above the desired temperature, the compressor (110) turns on. That is, the indoor temperature fluctuates within the temperature range from the desired temperature minus the offset value to the desired temperature plus the offset value. If the compressor (110) is repeatedly turned on and off, power consumption efficiency decreases, and the user may feel discomfort due to the inconsistent indoor temperature and indoor humidity.

[0098] The first control unit (190) of the disclosed air conditioner (1) can perform comfortable operation by appropriately adjusting the frequency of the compressor (110) without on-off control of the compressor (110) during dehumidification operation. During comfortable operation, the temperature of the indoor heat exchanger (230) can be maintained below the dew point temperature. Through comfortable operation, fluctuations in indoor temperature and indoor humidity can be reduced. Ideally, through comfortable operation, indoor temperature and indoor humidity can be maintained at a constant level. As fluctuations in indoor temperature and indoor humidity are reduced, power consumption efficiency can be improved, and a more comfortable indoor environment can be provided to the user.

[0099] A control method for an air conditioner (1) to perform comfortable operation during dehumidification operation is described below.

[0100] FIG. 5 is a flowchart illustrating a control method for an air conditioner according to one embodiment. FIG. 6 is a flowchart illustrating the control method for an air conditioner described in FIG. 5 in more detail.

[0101] Referring to FIG. 5, the first control unit (190) of the air conditioner (1) can detect indoor humidity by controlling the indoor humidity sensor (212) and detect indoor temperature by controlling the indoor temperature sensor (213) during dehumidification operation (501). The first control unit (190) can generate control signals to control the indoor humidity sensor (212) and the indoor temperature sensor (213). The second control unit (270) can control the indoor humidity sensor (212) and the indoor temperature sensor (213) according to the control signals transmitted from the first control unit (190), and transmit detection signals corresponding to the detected indoor humidity and the detected indoor temperature to the first control unit (190). The detection cycle of indoor humidity and indoor temperature can be determined in various ways depending on the design.

[0102] The first control unit (190) can determine whether conditions for performing comfortable operation are satisfied based on indoor humidity and indoor temperature (502). For example, referring to FIG. 6, when the indoor temperature becomes below a predetermined first threshold temperature and a desired temperature set by the user (601), and the indoor humidity becomes below a predetermined threshold humidity (602), comfortable operation can be started (603).

[0103] Specifically, the first control unit (190) of the air conditioner (1) can enter a comfortable operation based on the fact that, during a predetermined first time (e.g., 5 minutes) in the dehumidification operation, the indoor temperature is maintained below a predetermined first critical temperature (e.g., 23°C) and a desired temperature set by the user, and the indoor humidity is maintained below a predetermined critical humidity (e.g., 60%). The first time can be set to various values ​​within the range of 0 seconds to 10 minutes.

[0104] As another example, comfortable operation can be performed even when the indoor temperature is maintained lower than the desired temperature for a longer period than the first time (e.g., 10 minutes) during dehumidification operation.

[0105] The first control unit (190) can adjust the frequency of the compressor (110) to maintain the temperature of the indoor heat exchanger (230) below the dew point temperature in response to entry into comfortable operation (503). Specifically, the first control unit (190) can calculate the dew point temperature from the indoor humidity and indoor temperature during comfortable operation (604). A dew point temperature table containing multiple dew point temperature values ​​corresponding to multiple indoor humidity values ​​and multiple indoor temperature values ​​can be stored in advance in the memory (192). The first control unit (190) can obtain the dew point temperature corresponding to the current indoor humidity and current indoor temperature from the dew point temperature table.

[0106] The first control unit (190) can obtain the difference between the temperature of the indoor heat exchanger (230) and the dew point temperature, and the temperature change value of the indoor heat exchanger (230) (605). The temperature change value of the indoor heat exchanger (230) refers to the difference between the previous temperature of the indoor heat exchanger (230) detected at the previous detection time (N-1 cycle) and the current temperature of the indoor heat exchanger (230) detected at the current detection time (N cycle).

[0107] The first control unit (190) can determine to increase or decrease the frequency of the compressor (110) based on the difference between the temperature of the indoor heat exchanger (230) and the dew point temperature and the change in temperature of the indoor heat exchanger (230) (606). The first control unit (190) can determine the increase in frequency of the compressor (110) or the decrease in frequency of the compressor (110) corresponding to the difference between the temperature of the indoor heat exchanger (230) and the dew point temperature and the change in temperature of the indoor heat exchanger (230) from a fuzzy table (700) stored in memory (192). By adjusting the compressor frequency, the temperature of the indoor heat exchanger (230) can follow the dew point temperature.

[0108] Frequency control of the compressor (110) using a fuzzy table (700) is explained in detail in FIG. 7.

[0109] During comfortable operation, the first control unit (190) can determine whether the conditions for stopping comfortable operation are satisfied (504). The air conditioner (1) can return to dehumidification operation upon stopping comfortable operation (505). For example, the first control unit (190) can stop comfortable operation if, during a predetermined second time (e.g., 5 minutes) in comfortable operation, the indoor temperature is maintained at a second critical temperature (e.g., 26°C) or higher than a first critical temperature (e.g., 23°C). The first control unit (190) can stop comfortable operation if, during a predetermined second time (e.g., 5 minutes) in comfortable operation, the indoor humidity is maintained at a critical humidity (e.g., 60%) or higher.

[0110] As another example, the first control unit (190) may stop comfortable operation even when an error in the indoor humidity sensor (212) is detected. The first control unit (190) may determine that an error in the indoor humidity sensor (212) has occurred when a detection signal regarding indoor humidity is not received from the indoor unit (1b) or when a change in indoor humidity is identified as abnormal.

[0111] Additionally, the first control unit (190) of the air conditioner (1) can adjust the rotational speed of the outdoor fan (150) and the opening of the expansion valve (220) based on changes in the compressor frequency. A control data table containing the rotational speed of the outdoor fan (150) and the opening of the expansion valve (220) corresponding to the compressor frequency may be stored in advance in the first memory (192). For example, the first control unit (190) can increase the rotational speed of the outdoor fan (150) included in the outdoor unit (1a) and increase the opening of the expansion valve (220) included in the indoor unit (1b) in response to an increase in the frequency of the compressor (110). Conversely, the first control unit (190) can decrease the rotational speed of the outdoor fan (150) included in the outdoor unit (1a) and decrease the opening of the expansion valve (220) included in the indoor unit (1b) in response to a decrease in the frequency of the compressor (110).

[0112] In the comfort operation performed during the dehumidification operation, the frequency of the compressor (110) can be controlled to be relatively lower than the frequency of the compressor (110) in the dehumidification operation. Additionally, in the comfort operation, the first rotational speed of the compressor (110) can be adjusted to be slower than the second rotational speed of the compressor (110) in the dehumidification operation. As the frequency of the compressor (110) decreases, the rotational speed of the compressor (110) can also be slowed down. In the comfort operation, the third rotational speed of the outdoor fan (150) can also be adjusted to be slower than the fourth rotational speed of the outdoor fan (150) in the dehumidification operation.

[0113] Additionally, as described above, the frequency of the compressor (110) in the dehumidification operation is adjusted to be lower than the frequency of the compressor (110) in the cooling operation, and the rotational speed of the compressor (110) and the rotational speed of the outdoor fan (150) in the dehumidification operation are adjusted to be slower than the rotational speed of the compressor (110) and the rotational speed of the outdoor fan (150) in the cooling operation.

[0114] Accordingly, the frequency of the compressor (110) in comfortable operation is adjusted to be lower than the frequency of the compressor (110) in cooling operation, and the rotational speed of the compressor (110) and the rotational speed of the outdoor fan (150) in comfortable operation can be adjusted to be slower than the rotational speed of the compressor (110) and the rotational speed of the outdoor fan (150) in cooling operation.

[0115] The disclosed air conditioner (1) can reduce the variability of the compressor frequency by performing comfortable operation that maintains the temperature of the indoor heat exchanger (230) below the dew point temperature without on-off control of the compressor (110). In addition, the variability of the rotational speed of the outdoor fan (150) can also be reduced.

[0116] FIG. 7 illustrates a fuzzy table according to one embodiment.

[0117] Referring to the fuzzy table (700) of FIG. 7, the first control unit (190) of the air conditioner (1) can determine an increase or decrease value of the compressor frequency using the fuzzy table (700) that is stored in advance in memory (192). In the fuzzy table (700), Δfa represents an increase or decrease value of the compressor frequency as a control value of the compressor frequency.

[0118] Specifically, the air conditioner (1) can calculate the difference value (Td(N)) between the temperature of the indoor heat exchanger (230) and the dew point temperature and the temperature change value (ΔTd) of the indoor heat exchanger (230) at each predetermined detection cycle during comfortable operation. The temperature change value of the indoor heat exchanger (230) refers to the difference between the previous temperature (Td(N-1)) of the indoor heat exchanger (230) detected at the previous detection time (N-1 cycle) and the current temperature (Td(N)) of the indoor heat exchanger (230) detected at the current detection time (N cycle). That is, the temperature change value (ΔTd) of the indoor heat exchanger (230) can be obtained by subtracting the previous temperature (Td(N-1)) from the current temperature (Td(N)).

[0119] The first control unit (190) of the air conditioner (1) can determine a compressor frequency adjustment value (increase value or decrease value) corresponding to the difference value (Td(N)) between the temperature of the indoor heat exchanger (230) and the dew point temperature and the temperature change value (ΔTd) of the indoor heat exchanger (230) from the fuzzy table (700).

[0120] For example, in the fuzzy table (700) of FIG. 7, if the difference value (Td(N)) between the temperature of the indoor heat exchanger (230) and the dew point temperature is E1 and the temperature change value (ΔTd) of the indoor heat exchanger (230) is calculated as -dE2, the control value (Δfa) of the compressor frequency can be determined as -df1. The first control unit (190) can adjust the frequency of the compressor (110) by adding the control value (Δfa) to the current frequency of the compressor (110). That is, the frequency of the compressor (110) can be reduced by df1. The unit of the compressor frequency can be Hertz (Hz), and -df6 to df2 exemplified in FIG. 7 can be set to various values.

[0121] Figure 8 is a graph showing changes in indoor humidity, indoor temperature, and compressor frequency during normal dehumidification operation.

[0122] Referring to FIG. 8, when the dehumidification operation of the air conditioner (1) begins, the compressor (110) operates at a maximum frequency (f1) to rapidly lower the indoor temperature and indoor humidity. The compressor (110) operates at the maximum frequency (f1) until the indoor temperature reaches a predetermined first temperature (c1), and the compressor (110) is turned off at time t1 when the indoor temperature reaches the first temperature (c1). The first temperature (c1) may be a temperature lower than the set desired temperature by an offset value. As the indoor temperature decreases, the indoor humidity may also decrease. The indoor humidity may decrease after the start of the dehumidification operation and reach a first humidity (h1) at time t1. The first humidity (h1) may refer to the aforementioned critical humidity.

[0123] When the compressor (110) is turned off at time t1, the indoor temperature and indoor humidity increase again. At time t2, when the indoor temperature reaches a second temperature (c2), the compressor (110) is turned on again and operates at a maximum frequency (f1). The second temperature (c2) is a temperature higher than the set desired temperature by an offset value. As the compressor (110) operates, the indoor temperature and indoor humidity decrease again. Subsequently, at time t3, when the indoor temperature decreases and reaches the first temperature (c1) again, the compressor (110) is turned off again.

[0124] As shown in FIG. 8, in a normal dehumidification operation in which the compressor (110) is repeatedly turned on and off, it can be seen that the range of fluctuation in indoor temperature and indoor humidity is relatively large.

[0125] Figure 9 is a graph showing changes in indoor humidity, indoor temperature, and compressor frequency when comfortable operation is performed during dehumidification operation.

[0126] Referring to FIG. 9, the disclosed air conditioner (1) operates the compressor (110) at a maximum frequency (f1) to rapidly lower the indoor temperature and indoor humidity during dehumidification operation. However, unlike the general dehumidification operation described in FIG. 8, the disclosed air conditioner (1) can perform a comfortable operation by appropriately adjusting the frequency of the compressor (110) without on-off control of the compressor (110) from time t1, after a predetermined first time has elapsed since the indoor temperature reached a third temperature (c3) and the indoor humidity reached a third humidity (h3).

[0127] The third temperature (c3) may be lower than or equal to the desired temperature set by the user. Additionally, the third temperature (c3) may be lower than or equal to a predetermined first critical temperature. The third humidity (h3) may be lower than or equal to a predetermined critical humidity.

[0128] During comfortable operation, the frequency of the compressor (110) can be adjusted so that the temperature of the indoor heat exchanger (230) is maintained below the dew point temperature. During comfortable operation, the frequency of the compressor (110) can be adjusted based on the difference between the temperature of the indoor heat exchanger (230) and the dew point temperature, and the change in temperature of the indoor heat exchanger (230). During comfortable operation, the fluctuation range of the compressor frequency is smaller than the fluctuation range of the compressor frequency during normal dehumidification operation. After time t1, the air conditioner (1) can adjust the frequency of the compressor (110) using a fuzzy table (700). As a result, the frequency of the compressor (110) can follow an optimal frequency (f2) that is lower than the maximum frequency (f1). Accordingly, the temperature of the indoor heat exchanger (230) can follow the dew point temperature.

[0129] That is, as shown in FIG. 9, the frequency of the compressor (110) during the comfort operation performed during the dehumidification operation can be controlled to be relatively lower than the frequency of the compressor (110) during the dehumidification operation. In addition, the first rotational speed of the compressor (110) during the comfort operation can be adjusted to be slower than the second rotational speed of the compressor (110) during the dehumidification operation. As the frequency of the compressor (110) decreases, the rotational speed of the compressor (110) can also be slowed down. The third rotational speed of the outdoor fan (150) during the comfort operation can also be adjusted to be slower than the fourth rotational speed of the outdoor fan (150) during the dehumidification operation.

[0130] After time t1, as the frequency of the compressor (110) decreases, the indoor temperature may rise slightly and the indoor humidity may also rise slightly. However, the fluctuations in indoor temperature and indoor humidity are reduced, and ideally, the indoor temperature and indoor humidity can be maintained at a constant level.

[0131] As such, the disclosed air conditioner and its control method can reduce fluctuations in indoor temperature and indoor humidity by performing comfortable operation that appropriately adjusts the compressor frequency without on-off control of the compressor based on predetermined conditions during dehumidification operation. As fluctuations in indoor temperature and indoor humidity are reduced, power consumption efficiency can be improved, and a more comfortable indoor environment can be provided to the user.

[0132] Meanwhile, the disclosed embodiments may be implemented in the form of a storage medium that stores instructions executable by a computer. The instructions may be stored in the form of program code, and when executed by a processor, they may generate a program module to perform the operation of the disclosed embodiments.

[0133] A device-readable storage medium may be provided in the form of a non-transitory storage medium. Here, 'non-transitory storage medium' simply means that it is a tangible device and does not contain a signal (e.g., electromagnetic waves), and the term does not distinguish between cases where data is stored semi-permanently and cases where it is stored temporarily. For example, a 'non-transitory storage medium' may include a buffer in which data is stored temporarily.

[0134] Methods according to the various embodiments disclosed in this document may be provided as part of a computer program product. The computer program product may be traded between a seller and a buyer as a product. The computer program product may be distributed in the form of a device-readable storage medium (e.g., compact disc read-only memory (CD-ROM)), or distributed online (e.g., download or upload) through an application store (e.g., Play Store™) or directly between two user devices (e.g., smartphones). In the case of online distribution, at least a portion of the computer program product (e.g., downloadable app) may be temporarily stored or temporarily created on a device-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or a relay server.

[0135] As described above, the disclosed embodiments have been explained with reference to the attached drawings. Those skilled in the art will understand that the present invention may be practiced in forms different from the disclosed embodiments without changing the technical spirit or essential features of the invention. The disclosed embodiments are illustrative and should not be interpreted restrictively. Explanation of the symbols

[0136] 1: Air conditioner 1a: Outdoor unit 1b: Indoor unit 110: Compressor 120: Four-way valve 130: Outdoor heat exchanger 220: Expansion valve 230: Indoor heat exchanger

Claims

Claim 1 An air conditioner comprising: an indoor unit including an indoor heat exchanger; an outdoor unit including a compressor that supplies refrigerant to the indoor heat exchanger; an indoor heat exchanger temperature sensor that detects the temperature of the indoor heat exchanger; an indoor humidity sensor that detects indoor humidity; an indoor temperature sensor that detects the indoor temperature; and a control unit that performs a comfortable operation to maintain the temperature of the indoor heat exchanger below the dew point temperature based on the fact that, during a predetermined first time period in the dehumidification operation, the indoor temperature is maintained below a predetermined first threshold temperature and a desired temperature set by a user, and the indoor humidity is maintained below a predetermined threshold humidity, and during the comfortable operation, calculates the dew point temperature from the indoor humidity and the indoor temperature, and increases or decreases the frequency of the compressor based on the difference value between the temperature of the indoor heat exchanger and the dew point temperature and the change value of the temperature of the indoor heat exchanger during the comfortable operation, and stops the comfortable operation based on the fact that, during a predetermined second time period in the comfortable operation, the indoor temperature is maintained above a second threshold temperature which is higher than the first threshold temperature, or the indoor humidity is maintained above the threshold humidity. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 An air conditioner according to claim 1, wherein the control unit determines from a fuzzy table stored in memory an increase value of the compressor frequency or a decrease value of the compressor frequency corresponding to the difference value between the temperature of the indoor heat exchanger and the dew point temperature and the temperature change value of the indoor heat exchanger. Claim 6 An air conditioner according to claim 1, wherein the control unit increases the rotational speed of the outdoor fan included in the outdoor unit and increases the opening of the expansion valve included in the indoor unit in response to an increase in the frequency of the compressor, or decreases the rotational speed of the outdoor fan and decreases the opening of the expansion valve in response to a decrease in the frequency of the compressor. Claim 7 An air conditioner according to claim 1, wherein the control unit adjusts the first rotational speed of the compressor in the comfort operation to be slower than the second rotational speed of the compressor in the dehumidification operation, and adjusts the third rotational speed of the outdoor fan included in the outdoor unit in the comfort operation to be slower than the fourth rotational speed of the outdoor fan in the dehumidification operation. Claim 8 A control method for an air conditioner comprising an indoor unit including an indoor heat exchanger and an outdoor unit including a compressor that supplies refrigerant to the indoor heat exchanger, comprising: detecting indoor humidity using an indoor humidity sensor included in the indoor unit during a dehumidification operation; detecting indoor temperature using an indoor temperature sensor included in the indoor unit during the dehumidification operation; performing a comfortable operation to maintain the temperature of the indoor heat exchanger below the dew point temperature based on the fact that, during a predetermined first time period in the dehumidification operation, the indoor temperature is maintained below a predetermined first threshold temperature and a desired temperature set by a user, and the indoor humidity is maintained below a predetermined threshold humidity; calculating the indoor humidity and the dew point temperature from the indoor humidity; and adjusting the frequency of the compressor based on the temperature of the indoor heat exchanger and the dew point temperature during the comfortable operation. A method for controlling an air conditioner, comprising: stopping the comfortable operation based on the fact that, during a predetermined second time in the comfortable operation, the indoor temperature is maintained at a second critical temperature higher than the first critical temperature or the indoor humidity is maintained at a critical humidity higher than the first critical temperature; and controlling the frequency of the compressor by increasing or decreasing the frequency of the compressor based on the difference between the temperature of the indoor heat exchanger and the dew point temperature and the change in temperature of the indoor heat exchanger. Claim 9 delete Claim 10 delete Claim 11 delete Claim 12 A method for controlling an air conditioner according to claim 8, wherein adjusting the frequency of the compressor comprises determining from a fuzzy table stored in memory an increase value of the frequency of the compressor or a decrease value of the frequency of the compressor corresponding to the difference value between the temperature of the indoor heat exchanger and the dew point temperature and the temperature change value of the indoor heat exchanger. Claim 13 A control method for an air conditioner according to claim 8, further comprising: increasing the rotational speed of an outdoor fan included in the outdoor unit and increasing the opening of an expansion valve included in the indoor unit in response to an increase in the frequency of the compressor; or decreasing the rotational speed of the outdoor fan and decreasing the opening of the expansion valve in response to a decrease in the frequency of the compressor. Claim 14 A control method for an air conditioner according to claim 8, wherein the first rotational speed of the compressor in the comfort operation is adjusted to be slower than the second rotational speed of the compressor in the dehumidification operation, and the third rotational speed of the outdoor fan included in the outdoor unit in the comfort operation is adjusted to be slower than the fourth rotational speed of the outdoor fan in the dehumidification operation.

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