Refrigerator and method for controlling same

Abstract

A refrigerator according to an embodiment may comprise: a storage chamber; an evaporator; a compressor; a first electrode disposed in the storage chamber; a second electrode spaced apart from the first electrode; an RF power supply unit for applying an RF signal to the first electrode and the second electrode; a voltage control circuit for adjusting an input voltage of the RF power supply unit; a frequency control circuit for generating a switching signal for turning on or off the RF power supply unit; a voltage-current detector for detecting an output voltage between the first electrode and the second electrode and an output current of the first electrode; and a processor for operating the compressor, identifying an impedance change rate of food disposed between the first electrode and the second electrode on the basis of the output voltage and the output current, and adjusting a reference voltage applied to the voltage control circuit or an on / off duty ratio of the frequency control circuit on the basis of the impedance change rate of the food.

Description

Refrigerator and method of controlling it

[0001] The disclosed invention relates to a refrigerator and a method for controlling the same.

[0002] A refrigerator is a device that maintains food freshness by including a cabinet with a storage compartment and a cooling system that supplies cold air to the storage compartment. The refrigerator may include multiple storage compartments for storing food. For example, the storage compartment may include a refrigerator compartment maintained at approximately 0 to 5 degrees Celsius and used for refrigerated storage of food. The storage compartment may also include a freezer compartment maintained at approximately 0 to -30 degrees Celsius and used for frozen storage of food. A door is provided on the front of the cabinet to open and close the storage compartments. The refrigerator can independently cool the refrigerator compartment and the freezer compartment.

[0003] Additionally, the storage compartment can be divided into multiple storage spaces by shelves or containers, and the temperatures of each storage space can be controlled differently. To maintain different temperatures for each storage space, multiple evaporators can be provided to cool each storage space. However, arranging multiple evaporators in a refrigerator is inefficient and complicates the structure. Furthermore, it is difficult to precisely control the temperature of food stored within the storage space using only the evaporator.

[0004] Fresh foods like meat, fish, and fruits and vegetables have a relatively short shelf life, so they are often frozen when long-term storage is required. While freezing prevents spoilage, it can also degrade food quality due to moisture loss and damage to cell membranes caused by freezing.

[0005] The disclosed invention provides a refrigerator and a control method thereof that can directly and precisely control the temperature of food using genetic heating.

[0006] The disclosed invention provides a refrigerator and a control method thereof that can not only refrigerate and freeze food, but also maintain food in a non-frozen (supercooled) state and even thaw food.

[0007] In one embodiment, a refrigerator may include: a storage compartment; an evaporator for cooling the storage compartment; a compressor for supplying refrigerant to the evaporator; a first electrode disposed within the storage compartment; a second electrode disposed spaced apart from the first electrode within the storage compartment; an RF power supply unit for applying an RF signal to the first electrode and the second electrode; at least one voltage control circuit for controlling an input voltage of the RF power supply unit; a frequency control circuit for generating a switching signal for turning on or off the RF power supply unit; a voltage-current detector for detecting an output voltage between the first electrode and the second electrode and an output current of the first electrode; a memory for storing instructions; and at least one processor connected to the compressor, the at least one voltage control circuit, the frequency control circuit, the voltage-current detector, and the memory. When the above commands are executed by the at least one processor, the refrigerator can operate the compressor to cool the storage compartment, identify an impedance change rate of food placed between the first electrode and the second electrode based on the output voltage and the output current periodically detected by the voltage / current detector, and adjust a reference voltage applied to the at least one voltage control circuit or an on / off duty ratio of the frequency control circuit based on the impedance change rate of the food.

[0008] A method for controlling a refrigerator, comprising: a storage compartment; an evaporator for cooling the storage compartment; a compressor for supplying refrigerant to the evaporator; a first electrode disposed within the storage compartment; a second electrode disposed spaced apart from the first electrode within the storage compartment; an RF power supply unit for applying an RF signal to the first electrode and the second electrode; a DC converter for applying voltage to the RF power supply unit; and a power factor correction circuit for transmitting power factor-compensated power to the DC converter, the method comprising: operating the compressor to supply refrigerant to the evaporator to cool the storage compartment; identifying an impedance change rate of food disposed between the first electrode and the second electrode based on an output voltage between the first electrode and the second electrode and an output current of the first electrode, which are periodically detected by a voltage / current detector; And, based on the impedance change rate of the food, it may include adjusting a reference voltage applied to at least one voltage control circuit for adjusting the input voltage of the RF power supply unit, or adjusting an on-off duty ratio of a frequency control circuit for generating a switching signal for turning the RF power supply unit on or off.

[0009] The disclosed refrigerator and its control method can directly and precisely control the temperature of food using dielectric heating.

[0010] The disclosed refrigerator and its control method can not only refrigerate and freeze food, but also maintain food in a non-frozen (supercooled) state and even thaw food. Furthermore, the disclosed refrigerator and its control method can also ripen food.

[0011] The disclosed refrigerator and its control method can maintain a non-frozen (supercooled) state of food, thereby enabling long-term storage of food without deterioration in quality of the food.

[0012] The disclosed refrigerator and its control method can defrost frozen food, so that when a user needs to cook frozen food, the food can be quickly provided in a cookable state.

[0013] FIG. 1 illustrates a refrigerator with an open door according to one embodiment.

[0014] Figure 2 schematically illustrates a side cross-section of a refrigerator according to one embodiment.

[0015] Figure 3 is a control block diagram of a refrigerator according to one embodiment.

[0016] FIG. 4 illustrates a circuit system for genetically heating food according to one embodiment.

[0017] Figures 5 and 6 illustrate detailed circuit structures of the circuit system illustrated in Figure 4.

[0018] FIG. 7 illustrates a circuit system for genetically heating food according to one embodiment.

[0019] Figure 8 illustrates a detailed circuit structure of the circuit system illustrated in Figure 7.

[0020] FIG. 9 illustrates a circuit system for genetically heating food according to one embodiment.

[0021] FIG. 10 illustrates an example of a switching signal output by a frequency control circuit according to one embodiment.

[0022] FIG. 11 is an example of a graph showing changes in temperature of food and changes in food impedance in a non-freezing mode according to one embodiment.

[0023] FIG. 12 is another example of a graph showing temperature changes of food in a non-freezing mode according to one embodiment.

[0024] Fig. 13 is an example of a graph showing temperature changes of food in refrigeration mode according to one embodiment.

[0025] Fig. 14 is an example of a graph showing temperature changes of food in a defrosting mode according to one embodiment.

[0026] Fig. 15 is a flowchart illustrating a method for controlling a refrigerator according to one embodiment.

[0027] Fig. 16 is a flowchart explaining in more detail the control method of the refrigerator described in Fig. 15.

[0028] FIG. 17 is a flowchart illustrating a method that can be added to the control method of a refrigerator described in FIG. 15.

[0029] It should be understood that the various embodiments and terms used in this document are not intended to limit the technical features described in this document to specific embodiments, but rather to include various modifications, equivalents, or substitutes of the embodiments.

[0030] In connection with the description of the drawings, similar reference numerals may be used for similar or related components.

[0031] The singular form of a noun corresponding to an item may include one or more of said items, unless the relevant context clearly indicates otherwise.

[0032] In this document, each of the phrases "A or B", "at least one of A and B", "at least one of A or B", "A, B, or C", "at least one of A, B, and C", and "at least one of A, B, or C" may include any one of the items listed together in that phrase, or all possible combinations thereof.

[0033] The term "and / or" includes any combination of a plurality of related described elements or any one of a plurality of related described elements.

[0034] Terms such as "first," "second," or "first" or "second" may be used simply to distinguish one component from another and do not qualify the components in any other respect (e.g., importance or order).

[0035] In addition, terms such as 'front', 'rear', 'top', 'bottom', 'side', 'left', 'right', 'upper', and 'lower' used in the present disclosure are defined based on the drawings, and the shape and position of each component are not limited by these terms.

[0036] The terms "include" or "have" are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in this document, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0037] When a component is said to be “connected,” “coupled,” “supported,” or “in contact with” another component, this includes not only cases where the components are directly connected, coupled, supported, or in contact, but also cases where the components are indirectly connected, coupled, supported, or in contact through a third component.

[0038] When we say that a component is "on" another component, this includes not only cases where the component is in contact with the other component, but also cases where there is another component between the two components.

[0039] When a component (e.g., a first component) is referred to as being "coupled" or "connected" to another component (e.g., a second component), with or without the terms "functionally" or "communicatively," it means that the component can be connected to the other component directly (e.g., wired), wirelessly, or through a third component.

[0040] A refrigerator (1) according to one embodiment may include a cabinet.

[0041] A "cabinet" may include an inner case, an outer case disposed outside the inner case, and insulation provided between the inner case and the outer case.

[0042] The "inner case" may include at least one of a case, plate, panel, or liner forming a storage compartment. The inner case may be formed as a single body, or may be formed by assembling a plurality of plates. The "outer case" may form the exterior of the cabinet, and may be joined to the exterior of the inner case so that insulation is placed between the inner case and the outer case.

[0043] "Insulation" can insulate the interior and exterior of a storage room so that the temperature inside the storage room can be maintained at a set temperature without being affected by the external environment. In one embodiment, the insulation can include foam insulation. The foam insulation can be formed by injecting and foaming urethane foam, a mixture of polyurethane and a foaming agent, between the inner and outer layers.

[0044] In one embodiment, the insulation may include a vacuum insulation material in addition to the foam insulation, or the insulation may consist solely of the vacuum insulation material instead of the foam insulation. The vacuum insulation material may include a core material and an outer shell material that accommodates the core material and seals the interior under a vacuum or near-vacuum pressure. However, the insulation material is not limited to the foam insulation or vacuum insulation material described above, and may include various materials that can be used for insulation.

[0045] A "storage room" may include a space defined by an interior wall. The storage room may further include an interior wall defining a corresponding space. The storage room may store various items, such as food, medicine, and cosmetics, and the storage room may be configured to be open on at least one side for the entry and exit of items.

[0046] A refrigerator (1) may include one or more storage compartments. When two or more storage compartments are formed in the refrigerator (1), each storage compartment may have a different purpose and may be maintained at different temperatures. To this end, each storage compartment may be separated from the other by a partition wall containing insulating material.

[0047] The storage room may be designed to maintain an appropriate temperature range depending on its intended use, and may include a "refrigerator," a "freezer," or a "variable temperature room," which are distinguished by their intended use and / or temperature range. A refrigerator may be maintained at a temperature appropriate for refrigerating items, and a freezer may be maintained at a temperature appropriate for freezing items. "Refrigeration" may mean cooling items to a temperature that does not freeze them, and for example, a refrigerator may be maintained at a temperature ranging from 0 degrees Celsius to +7 degrees Celsius. "Freezing" may mean cooling items to freeze or maintain them in a frozen state, and for example, a freezer may be maintained at a temperature ranging from -20 degrees Celsius to -1 degree Celsius. A variable temperature room may be used as either a refrigerator or a freezer, at the user's option or not.

[0048] In addition to names such as "refrigerator," "freezer," and "variable temperature room," a storage room may also be called by various other names such as "vegetable room," "fresh room," "cooling room," and "ice room." The terms "refrigerator," "freezer," and "variable temperature room" used hereinafter should be understood to encompass storage rooms having corresponding uses and temperature ranges.

[0049] According to one embodiment, the refrigerator (1) may include at least one door configured to open and close an open side of a storage compartment. The door may be configured to open and close each of one or more storage compartments, or a single door may be configured to open and close multiple storage compartments. The door may be installed on the front of the cabinet in a pivotal or sliding manner.

[0050] The "door" may be configured to seal the storage compartment when the door is closed. The door may include insulation, similar to a cabinet, to insulate the storage compartment when the door is closed.

[0051] According to one embodiment, the door may include a door outer panel forming the front of the door, a door inner panel forming the back of the door and facing the storage compartment, an upper cap, a lower cap, and door insulation provided on the interior of these.

[0052] The door inner panel may be provided with a gasket that seals the storage compartment by pressing against the front of the cabinet when the door is closed. The door inner panel may include a dyke that protrudes rearward to accommodate a door basket for storing items.

[0053] In one embodiment, the door may include a door body and a front panel detachably coupled to the front side of the door body and forming the front of the door. The door body may include a door outer panel forming the front of the door body, a door inner panel forming the rear of the door body and facing the storage compartment, an upper cap, a lower cap, and door insulation provided inside these.

[0054] The refrigerator (1) can be classified into a French door type, a side-by-side type, a bottom mounted freezer (BMF), a top mounted freezer (TMF), or a single-door refrigerator (1) depending on the arrangement of the door and storage compartment.

[0055] According to one embodiment, the refrigerator (1) may include a cold air supply device configured to supply cold air to the storage compartment.

[0056] A "cold air supply device" may include a system of machines, devices, electronic devices and / or combinations thereof that can generate cold air and guide the cold air to cool a storage room.

[0057] In one embodiment, the cold air supply device can generate cold air through a refrigeration cycle comprising the processes of compression, condensation, expansion, and evaporation of a refrigerant. To this end, the cold air supply device can include a refrigeration cycle system having a compressor, a condenser, an expansion device, and an evaporator capable of driving the refrigeration cycle. In one embodiment, the cold air supply device can include a semiconductor, such as a thermoelectric element. The thermoelectric element can cool a storage compartment through heat generation and cooling through the Peltier effect.

[0058] According to one embodiment, the refrigerator (1) may include a machine room in which at least some components belonging to the cold air supply device are arranged.

[0059] The "machine room" may be designed to be partitioned and insulated from the storage room to prevent heat generated by components placed within the machine room from being transferred to the storage room. The interior of the machine room may be configured to be connected to the exterior of the cabinet to dissipate heat from components placed within the machine room.

[0060] According to one embodiment, the refrigerator (1) may include a dispenser provided on the door to provide water and / or ice. The dispenser may be provided on the door so that it is accessible to a user without opening the door.

[0061] According to one embodiment, a refrigerator (1) may include an ice-making device configured to produce ice. The ice-making device may include an ice-making tray that stores water, an ice-separating device that separates ice from the ice-making tray, and an ice bucket that stores ice produced in the ice-making tray.

[0062] According to one embodiment, a refrigerator (1) may include a control unit for controlling the refrigerator (1). The refrigerator (1) may include at least one control unit. The control unit may generate a control signal for controlling the operation of a cold air supply device. For example, the control unit may receive temperature information of a storage compartment from a temperature sensor and generate a cooling control signal for controlling the operation of a cold air supply device based on the temperature information of the storage compartment.

[0063] Hereinafter, embodiments according to the present invention will be described in detail with reference to the attached drawings.

[0064] It should be understood that each block and combination of flowcharts can be performed by one or more computer programs containing instructions. One or more computer programs may be stored entirely in a single memory device, or one or more computer programs may be divided into multiple parts and stored in multiple memory devices.

[0065] The functions or operations described herein may be processed by a single processor or a combination of processors. A single processor or a combination of processors is a circuit that performs processing and may include circuits such as an application processor (AP, e.g., a central processing unit (CPU)), a communication processor (CP, e.g., a modem), a graphics processing unit (GPU), a neural processing unit (NPU) (e.g., an artificial intelligence (AI) chip), a wireless fidelity (Wi-Fi) chip, a Bluetooth chip, a global positioning system (GPS) chip, a near-field communication (NFC) chip, a connection chip, a sensor controller, a touch controller, a fingerprint sensor controller, a display driver integrated circuit (IC), an audio codec chip, a universal serial bus (USB) controller, a camera controller, an image processing IC, a microprocessor unit (MPU), a system on a chip (SoC), an IC, and the like.

[0066] FIG. 1 illustrates a refrigerator with an open door according to one embodiment. FIG. 2 schematically illustrates a side cross-section of the refrigerator according to one embodiment.

[0067] Referring to FIGS. 1 and 2, a refrigerator (1) may include a cabinet (10), a storage compartment (20) formed by being divided vertically inside the cabinet (10), and a door (30) for opening and closing the storage compartment (20). In addition, the refrigerator (1) may include a cold air supply device for supplying cold air to the storage compartment (20).

[0068] The cabinet (10) may include an inner case (11) forming a storage room (20), an outer case (12) bonded to the outside of the inner case (11) to form an exterior, and an insulating material (13) foamed between the inner case (11) and the outer case (12) to insulate the storage room (20).

[0069] The storage room (20) can be divided into a plurality of storage rooms (22, 23, 24) by partitions (15). For example, the storage room (20) can be divided into a plurality of storage rooms (22, 23, 24) by partitions (15). The partition (15) can include a first partition (17) and a second partition (19). When the first partition (17) and the second partition (19) are combined, the partition (15) can have a T-shape. The partition (15) can divide the storage room (20) into three spaces.

[0070] The first partition (17) can be horizontally connected to the inside of the storage compartment (20) to divide the storage compartment (20) into an upper storage compartment (22) and a lower storage compartment (23, 24). The second partition (19) can be vertically connected to the lower storage compartment (23, 24) to divide the lower storage compartment (23, 24) into a first lower storage compartment (23) and a second lower storage compartment (24). The upper storage compartment (22) can be used as a refrigerator. At least one of the two lower storage compartments (23, 24) can be used as a freezer.

[0071] For example, both the first lower storage chamber (23) and the second lower storage chamber (24) can be used as a freezer. The first lower storage chamber (23) can be used as a freezer and the second lower storage chamber (24) can be used as a refrigerator. The first lower storage chamber (23) can be used as a freezer and the second lower storage chamber (24) can be used as a refrigerator. Both the first lower storage chamber (23) and the second lower storage chamber (24) can be used as refrigerators.

[0072] The storage room (20) is not limited to the exemplified one. The storage room (20) may be formed in various ways depending on the design. A plurality of shelves (25) and storage containers (26, 36) may be provided inside the storage room (20) to store food, etc. A plurality of storage containers (26, 36) may be provided. Each of the plurality of storage containers (26, 36) may be defined as a storage room. For example, one storage container may be described as one storage room. A first storage container (26) may be provided in the upper storage room (22), and a second storage container (36) may be provided in the lower storage room (23, 24). The plurality of shelves (25) may divide one storage room into a plurality of storage spaces. In addition, each of the plurality of storage containers (26, 36) may be arranged in a storage space.

[0073] A refrigerator (1) may include a door (30). The door (30) may open or close each of the upper storage compartment (22) and the lower storage compartments (23, 24). The door (30) may be rotatably coupled to the cabinet (10). The door (30) may include a pair of upper doors (31) and a pair of lower doors (33). The upper door (31) may open and close the upper storage compartment (22). The lower door (33) may open and close the lower storage compartments (23, 24).

[0074] A pair of upper doors (31) may be provided with a first door handle (32a) and a second door handle (32b). Part of or all of the upper storage compartment (22) may be opened or closed by at least one of the pair of upper doors (31). A freezer door handle (34) may be provided on each of the pair of lower doors (33). The lower doors (33) may also be provided as sliding doors.

[0075] When the upper door (31) is closed, a rotation bar (35) may be provided on at least one of the pair of upper doors (31) so that the upper doors (31) can be sealed without a gap being created between them. The rotation bar (35) may be rotatably coupled to at least one of the pair of upper doors (31). The rotation bar (35) may be rotated by a rotation guide (14) formed on the cabinet (10) according to the opening and closing of the upper door (31).

[0076] Door shelves (31a, 33a) for storing food may be provided on the back surfaces of the upper door (31) and the lower door (33). Shelf supports (31b, 33b) for supporting the left and right sides of the door shelves (31a, 33a) may be provided on each of the upper door (31) and the lower door (33). The shelf supports (31b, 33b) may be provided to be detachable on each of the doors (31, 33).

[0077] A first gasket (31c, 33c) may be provided on the back edge of each of the upper door (31) and the lower door (33) to seal the gap with the cabinet (10) when the door (31, 33) is closed. The first gasket (31c, 33c) may be installed in a loop shape along the back edge of each door (31, 33) and may include a magnet inside.

[0078] The upper door (31) may be provided as a double door including a first door (40) and a second door (50). The first door (40) is rotatably connected to the cabinet (10) by a hinge and can open and close the upper storage compartment (22). The door shelf (31a), shelf support (31b), and first gasket (31c) described above may be provided on the first door (40).

[0079] The first door (40) may include an opening (41). A user may store food on the door shelf (31a) or take food out of the door shelf (31a) through the opening (41) while the first door (40) is closed. The opening (41) passes through the first door (40) and may be opened and closed by the second door (50).

[0080] A second door (50) is provided in front of the first door (40) so as to open and close the opening (41) of the first door (40). The second door (50) may be provided so as to be rotatable in the same direction as the first door (40). For example, the second door (50) may be rotatably supported by a hinge installed on the first door (40). The hinge may also be installed on the cabinet (10).

[0081] The second door (50) may include a second gasket to maintain airtightness with the first door (40). The second gasket may be installed in a loop shape along the edge of the back surface of the second door (50) and may include a magnet inside.

[0082] A machine room (27) may be formed at the lower rear side of the cabinet (10). A cooling cycle system may be arranged in the machine room (27). The cooling cycle system may include a compressor (70) for compressing refrigerant, a condenser for condensing the refrigerant, an expansion device for expanding the refrigerant condensed by the condenser, an evaporator (81, 82) installed at the rear of the storage room (20) for cooling the surrounding air, and a fan (F2, F3) for moving the air cooled by the evaporator (81, 82) to the storage room (20). The refrigerator (1) may include a cold air duct (61, 62) for guiding cold air flowing according to the operation of the fan (F2, F3) to the storage room (20). The cold air duct (61, 62) may be provided at the rear side of the storage room (20).

[0083] The first cold air duct (61), the first evaporator (81), and the first fan (F1) may be arranged at the rear of the upper storage chamber (22). Air cooled by the first evaporator (81) may move to the upper storage chamber (22) through the first cold air duct (61) according to the operation of the first fan (F1). The second cold air duct (62), the second evaporator (82), and the second fan (F2) may be arranged at the rear of the lower storage chamber (23, 24). Air cooled by the second evaporator (82) may move to the lower storage chamber (23, 24) through the second cold air duct (62) according to the operation of the second fan (F2).

[0084] A plurality of electrodes (90) may be arranged within the storage compartment (20). The plurality of electrodes (90) may be arranged parallel to each other and spaced apart from each other. For example, the refrigerator (1) may include a first electrode (90a) and a second electrode (90b) arranged within the lower storage compartment (23, 24). The first electrode (90a) and the second electrode (90b) may be arranged spaced apart from each other and parallel to each other. The first electrode (90a) and the second electrode (90b) may be arranged to face each other. The first electrode (90a) may be positioned above the second electrode (90b). The first electrode (90a) and the second electrode (90b) may be arranged parallel to the upper and lower surfaces of the storage compartment (20). Each of the first electrode (90a) and the second electrode (90b) may be included in a shelf. The first electrode (90a) and the second electrode (90b) may be fixed to the inner surface (11) or may be provided to be detachable.

[0085] The number and location of the electrodes (90) are not limited to those exemplified. For example, three or more electrodes may be spaced apart and parallel to each other within the lower storage chamber (23, 24). A plurality of electrodes (90) may also be spaced apart and parallel to each other within the upper storage chamber (22). In addition, the length, area, and / or thickness of the electrodes (90) may also vary depending on the design.

[0086] Each of the plurality of electrodes (90) may be electrically connected to an RF power supply unit (140) described below. When an RF signal is applied to the plurality of electrodes (90), an electric field may be generated between the first electrode (90a) and the second electrode (90b). The electric field may vibrate a dielectric (e.g., water molecules) contained in the food. When the dielectric (e.g., water molecules) vibrates, dipole frictional heat may be generated, thereby heating the dielectric.

[0087] Food can be placed between the first electrode (90a) and the second electrode (90b). For example, the first electrode (90a) and the second electrode (90b) can divide the storage compartment (20) into a plurality of receiving spaces. Food can be placed in the receiving spaces between the first electrode (90a) and the second electrode (90b). A storage container (26, 36) containing food can also be placed between the first electrode (90a) and the second electrode (90b). When an electric field is generated between the first electrode (90a) and the second electrode (90b), the food can be heated. The temperature of the food placed between the first electrode (90a) and the second electrode (90b) can be controlled independently of the temperature of the storage compartment (20).

[0088] The polarity of each of the plurality of electrodes (90) can be determined according to the phase of the RF signal applied to each of the plurality of electrodes (90). Depending on the polarity of each of the plurality of electrodes (90), an electric field may or may not be generated between the plurality of electrodes (90). The magnitude of the electric field generated between the plurality of electrodes (90) may vary depending on the magnitude of the RF signal applied to the plurality of electrodes (90). For example, the polarity of the first electrode (90a) may be plus (+) and the polarity of the second electrode (90b) may be minus (-). In this case, the second electrode (90b) corresponds to the ground electrode, and an electric field may be generated between the first electrode (90a) and the second electrode (90b).

[0089] Figure 3 is a control block diagram of a refrigerator according to one embodiment.

[0090] Referring to FIG. 3, the refrigerator (1) may include a control unit (300). The control unit (300) may include a processor (320) and a memory (310). The memory (310) may include volatile memory (e.g., S-RAM, D-RAM) and non-volatile memory (e.g., ROM, EPROM). The processor (320) and the memory (310) may be implemented as separate chips or as a single chip. In addition, a plurality of processors and a plurality of memories may be provided.

[0091] The control unit (300) and / or the processor (320) can be electrically connected to various electronic devices and / or electronic components of the refrigerator (1) and can control the electronic devices and / or electronic components. The control unit (300) and / or the processor (320) can control the operation of the refrigerator (1).

[0092] The processor (320) can process various data and signals using instructions, data, programs, and / or software stored in the memory (310). The processor (320) can generate control signals for controlling components of the refrigerator (1). The processor (320) may include one core or multiple cores.

[0093] The processor (320) may be configured to perform various operations of the refrigerator (1). The processor (320) may perform operations of the refrigerator (1) according to various embodiments by executing at least one instruction, algorithm, program, and / or software stored in the memory (310). The processor (320) may control one or any combination of components of the refrigerator (1). The processor (320) may include a main processor and at least one sub-processor. Various electronic devices and / or electronic components of the refrigerator (1) may be controlled by separate processors or by a single integrated processor.

[0094] The processor (320) may include various types of circuits. For example, the processor (320) may include one or more of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an APU (Accelerated Processing Unit), a MIC (Many Integrated Core), a DSP (Digital Signal Processor), an NPU (Neural Processing Unit), a hardware accelerator, or a machine learning accelerator.

[0095] The disclosed refrigerator (1) may include a cooling cycle system for cooling a storage compartment (20) and a circuit system for dielectrically heating food. The refrigerator (1) can independently cool the storage compartment (20) and heat food. The refrigerator (1) can directly heat food placed within the storage compartment (20) by applying an electric field to the food while cooling the storage compartment (20). Therefore, the refrigerator (1) can store food at various temperatures and precisely control the temperature of the food.

[0096] The refrigeration cycle system may include a compressor (70) that compresses refrigerant, a condenser that condenses refrigerant, a flow switching valve (74) that switches the flow path of refrigerant discharged from the condenser, an expansion device that expands the refrigerant condensed by the condenser, a first evaporator (81) that cools air supplied to the upper storage chamber (22), a second evaporator (82) that cools air supplied to the lower storage chamber (23, 24), a first fan (F1) that moves cooled air to the upper storage chamber (22), a second fan (F2) that moves cooled air to the lower storage chamber (23, 24), and a third fan (F3) that supplies air to the condenser.

[0097] The compressor (70) can suck in refrigerant and compress the sucked refrigerant to change it into a high-temperature, high-pressure gas. The sucking of the refrigerant can be performed using the rotational power of a built-in motor. The compressor (70) can compress the sucked low-temperature, low-pressure refrigerant and discharge the high-temperature, high-pressure refrigerant. The refrigerant is discharged from the compressor (70) in a gaseous state. By sucking and discharging the refrigerant by the compressor (70), the refrigerant can circulate within the cooling cycle.

[0098] The high-temperature, high-pressure refrigerant discharged from the compressor (70) is delivered to the condenser. The condenser is connected to the discharge port of the compressor (70) and condenses the gaseous refrigerant discharged from the compressor (70) into a liquid state by exchanging heat with the surrounding air. Inside the condenser, the refrigerant liquefies and releases heat to the outside, thereby lowering the temperature of the refrigerant.

[0099] The processor (320) can control the operating frequency and / or rotational speed (RPM) of the compressor (70). As the operating frequency and / or rotational speed (RPM) of the compressor (70) increases, the heat released around the condenser can increase.

[0100] The flow switching valve (74) can switch the flow path of the refrigerant discharged from the condenser depending on the operation mode of the refrigerator (1) (e.g., refrigeration mode or freezing mode). The processor (320) can control the flow switching valve (74) to guide the refrigerant to the first evaporator (81) or the second evaporator (82) depending on the operation mode of the refrigerator (1) (e.g., refrigeration mode or freezing mode). The flow switching valve (74) can guide the refrigerant discharged from the condenser to the first evaporator (81) or the second evaporator (82). In the refrigeration operation for cooling the upper storage chamber (22), the flow switching valve (74) can guide the refrigerant to the first evaporator (81). In the freezing operation for cooling the lower storage chambers (23, 24), the flow switching valve (74) can guide the refrigerant to the second evaporator (82). Refrigeration operation for cooling the upper storage chamber (22) and freezing operation for cooling the lower storage chambers (23, 24) can be performed independently using the Euro switching valve (74).

[0101] The expansion device may include a refrigerator expansion device and a freezer expansion device. The expansion device may expand the liquid refrigerant flowing from the flow diverter valve (74). The temperature and pressure of the refrigerant may decrease as it passes through the expansion device. The refrigerant expanded in the expansion device may be a two-phase refrigerant comprising a liquid component and a gas component.

[0102] The expansion device may be provided with an expansion valve. The expansion valve may include various types of valves, such as a thermoelectric electronic expansion valve that utilizes the deformation of a bimetal, a thermal electronic expansion valve that utilizes volume expansion due to heating of an encapsulating 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.

[0103] The expansion device may be formed as a capillary tube. The capillary tube may be implemented by a thin tube, and the refrigerant passing through the capillary tube is forced and delivered to the evaporator (81, 82).

[0104] Each of the first evaporator (81) and the second evaporator (82) can cool air. The refrigerant flowing inside the evaporators (81, 82) exchanges heat with the air surrounding the evaporators (81, 82) and absorbs heat from the surrounding air, so that the air that has exchanged heat with the refrigerant can be cooled. The cooled air can be supplied to the storage chamber (20) according to the operation of the fans (F1, F2).

[0105] The first fan (F1) can move the air cooled by the first evaporator (81) to the upper storage chamber (22). The second fan (F2) can move the air cooled by the second evaporator (82) to the lower storage chambers (23, 24). The processor (320) can control the rotation speeds of each of the first fan (F1) and the second fan (F2). As the first fan (F1) operates, heat exchange between the refrigerant flowing inside the first evaporator (81) and the air can occur smoothly. As the second fan (F2) operates, heat exchange between the refrigerant flowing inside the second evaporator (82) and the air can occur smoothly.

[0106] The third fan (F3) is positioned around the condenser and can supply air toward the condenser. The operation of the third fan (F3) can be synchronized with the operation of the compressor (70). For example, the processor (320) can operate the third fan (F3) when the compressor (70) starts, and can stop the third fan (F3) when the compressor (70) stops. In addition, the processor (320) can increase the rotation speed of the third fan (F3) when the operating frequency and / or rotation speed (RPM) of the compressor (70) increases. As the third fan (F3) operates, heat exchange between the refrigerant flowing inside the condenser and the air can be performed more quickly.

[0107] A refrigerator (1) may include a first temperature sensor (91), a second temperature sensor (92), and a food sensor (93). The first temperature sensor (91) may correspond to a 'refrigerator temperature sensor', and the second temperature sensor (92) may correspond to a 'freezer temperature sensor'.

[0108] The first temperature sensor (91) can detect the temperature of the upper storage chamber (22). The first temperature sensor (91) can be located inside the upper storage chamber (22). The first temperature sensor (91) can transmit an electrical signal corresponding to the temperature of the upper storage chamber (22) to the processor (320). The processor (320) can identify the temperature of the upper storage chamber (22) based on the electrical signal transmitted from the first temperature sensor (91).

[0109] The second temperature sensor (92) can detect the temperature of the lower storage chamber (23, 24). The second temperature sensor (92) can be located inside the lower storage chamber (23, 24). The second temperature sensor (92) can transmit an electrical signal corresponding to the temperature of the lower storage chamber (23, 24) to the processor (320). The processor (320) can identify the temperature of the lower storage chamber (23, 24) based on the electrical signal transmitted from the second temperature sensor (92).

[0110] The food sensor (93) may include various sensors for identifying food. For example, the food sensor (93) may include a camera, a light sensor (e.g., an infrared sensor), a weight sensor, and / or a temperature sensor. The food sensor (93) may acquire image data of the food, weight data of the food, and / or temperature data of the food.

[0111] The processor (320) can identify food placed in the storage room (20) using image data, weight data, and / or temperature data acquired by the food sensor (93). The processor (320) can process the image data, weight data, and / or temperature data using various artificial intelligence algorithms (e.g., deep learning algorithms), and can identify food from the image data, weight data, and / or temperature data. In addition, the processor (320) can process various data acquired by the food sensor (93) to identify the type, amount, volume, and / or size of the food.

[0112] A circuit system for genetically heating food may include an EMI (Electro Magnetic Interference) filter (110), a power factor correction circuit (120), a DC converter (130), an RF power supply (140), an impedance matching circuit (150), and an electrode (90). In addition, the circuit system may include a voltage / current detector (160) for detecting an output voltage and an output current of the electrode (90), at least one voltage control circuit (170, 180) for controlling an input voltage of the RF power supply (140), and a frequency control circuit (190) for generating a switching signal for turning on or off the RF power supply (140).

[0113] An EMI (Electro Magnetic Interference) filter (110) can remove noise contained in AC power supplied from a commercial power source (AC). The EMI filter (110) can be provided as a circuit in which various electronic components, such as capacitors, inductors, and diodes, are connected in parallel and / or in series. The EMI filter (110) can discharge noise contained in AC power through a ground line. The EMI filter (110) can be provided as a passive filter or an active filter.

[0114] The power factor correction circuit (120) can compensate for the power factor of AC power. The power factor correction circuit (120) can compensate for the power factor by reducing or eliminating reactive power among the active power and reactive power that constitute the AC power. By compensating for the power factor, power loss can be reduced. The power factor correction circuit (120) can be provided as a circuit in which various electronic components, such as capacitors, inductors, and diodes, are connected in parallel and / or in series. The power factor correction circuit (120) can be controlled by the control unit (300).

[0115] The DC converter (130) can convert the power output from the power factor correction circuit (120) into DC power suitable for the RF power supply (140). The DC converter (130) can transmit the converted DC power to the RF power supply (140). The DC converter (130) can apply voltage to the RF power supply (140). The DC converter (130) can be provided as a circuit in which various electronic elements such as transistors, inductors, and diodes are connected in parallel and / or in series.

[0116] The RF power supply unit (140) can generate an RF signal and apply the RF signal to the electrodes (90). A sinusoidal power can be applied to the electrodes (90) by the RF signal. The control unit (300) can control the RF power supply unit (140) to generate an electric field between the plurality of electrodes (90). Depending on the operation of the RF power supply unit (140), an electric field for dielectric heating of food placed between the plurality of electrodes (90) can be generated.

[0117] An impedance matching circuit (150) may be provided between the RF power supply unit (140) and the electrode (90). An RF signal generated by the RF power supply unit (140) may be transmitted to the electrode (90) through the impedance matching circuit (150).

[0118] The impedance matching circuit (150) can match the output impedance of the RF power supply unit (140) and the electrode impedance of the electrode (90). If there is a difference between the output impedance of the RF power supply unit (140) and the electrode impedance of the electrode (90), reflected power is generated from the electrode (90), and power transmission efficiency is reduced. In order to minimize the reflected power, matching of the output impedance of the RF power supply unit (140) and the electrode impedance of the electrode (90) needs to be performed. The control unit (300) can perform impedance matching by controlling the impedance matching circuit (150).

[0119] Electrode impedance may vary depending on the condition of the food placed between the multiple electrodes (90). For example, electrode impedance may vary depending on various factors such as the type of food, the size of the food, the amount of water contained in the food, and the temperature of the storage chamber (20) in which the food is placed. Therefore, electrode impedance may correspond to the impedance of the food.

[0120] If a dielectric having a high permittivity (e.g., a food having a high moisture content) exists between the first electrode (90a) and the second electrode (90b), the strength of the electric field formed between the first electrode (90a) and the second electrode (90b) may decrease because charges accumulate in the dielectric. If the strength of the electric field decreases, the magnitude of the output voltage detected between the first electrode (90a) and the second electrode (90b) may decrease, and the impedance of the food may be determined to be small.

[0121] The higher the moisture content of a food, the lower its impedance may appear. Furthermore, the lower the temperature of the food, the higher its impedance may appear. As the temperature of the food decreases, the kinetic energy of water molecules and dissolved ions decreases, and ion mobility decreases, making charge transfer more difficult. This reduces electrical conductivity and increases impedance. In other words, the impedance of a food can be inversely proportional to its temperature.

[0122] The voltage / current detector (160) can detect the output voltage and output current of the electrode (90). For example, the voltage / current detector (160) can detect the output voltage between the first electrode (90a) and the second electrode (90b) and the output current of the first electrode (90a). The voltage / current detector (160) can detect the output voltage between the first electrode (90a) and the second electrode (90b) and the output current of the first electrode (90a) at predetermined time intervals. The voltage / current detector (160) can transmit an electrical signal corresponding to the detected output voltage and output current of the electrode (90) to the control unit (300). The processor (320) can determine the impedance of the food based on the output voltage and output current of the electrode (90) obtained from the voltage / current detector (160).

[0123] The processor (320) can control the voltage / current detector (160) to periodically detect the output voltage between the first electrode (90a) and the second electrode (90b) and the output current of the first electrode (90a). The processor (320) can identify the impedance change rate of the food based on the output voltage and output current of the electrode (90) detected periodically. The impedance change rate of the food can represent the amount of impedance change of the food per unit time.

[0124] For example, when food is placed between the first electrode (90a) and the second electrode (90b) in the lower storage chamber (23, 24) and the operation mode of the lower storage chamber (23, 24) is set to the freezing mode, the temperature of the food may decrease nonlinearly and then converge to a specific temperature (e.g., a target temperature). As the food cools, the impedance change rate of the food may gradually decrease. When the food is cooled, the impedance of the food may nonlinearly increase and then converge to a specific impedance.

[0125] At least one voltage control circuit (170, 180) may be connected to at least one of the DC converter (130) and the power factor correction circuit (120). For example, the refrigerator (1) may include at least one of a first voltage control circuit (170) connected to an output terminal of the DC converter (130) and a second voltage control circuit (180) connected to an output terminal of the power factor correction circuit (120). The processor (320) may control the at least one voltage control circuit (170, 180) to adjust the input voltage of the RF power supply (140). The processor (320) may control the input voltage of the RF power supply (140) by adjusting the reference voltage applied to the at least one voltage control circuit (170, 180). When the input voltage of the RF power supply unit (140) is adjusted, the size of the RF power supplied to the plurality of electrodes (90) can be adjusted, and the strength of the electric field generated between the plurality of electrodes (90) can be adjusted.

[0126] The frequency control circuit (190) can generate a switching signal to turn on or off the RF power supply unit (140). The processor (320) can adjust the on / off duty ratio of the frequency control circuit (190). The on / off duty ratio of the frequency control circuit (190) can represent a ratio of the on time and the off time of the frequency control circuit (190). When the frequency control circuit (190) is turned on, a switching signal is output, and when the frequency control circuit (190) is turned off, the output of the switching signal can be stopped. As the on / off duty ratio increases, the output time of the switching signal can increase. The on / off duty ratio of the frequency control circuit (190) can also be described as the on / off duty ratio of the RF power supply unit (140).

[0127] In addition, the processor (320) can adjust the frequency of the switching signal generated by the frequency control circuit (190). The frequency of the switching signal may also be referred to as a 'switching frequency'. The higher the frequency of the switching signal, the shorter the cycle of the switching signal. As the frequency of the switching signal increases, the switching speed of the switching element (SW_pa1) included in the RF power supply unit (140) can increase. As the switching speed of the switching element (SW_pa1) increases, a large amount of RF power can be supplied from the RF power supply unit (140) to the electrode (90).

[0128] A refrigerator (1) may include a user interface (210). The user interface (210) may perform interaction between a user and the refrigerator (1). The user interface (210) may obtain user input and display various information regarding the refrigerator (1). The user interface (210) may be provided at various locations of the refrigerator (1). The user interface (210) may include at least one input interface (211) and at least one output interface (212).

[0129] For example, the input interface (211) can convert sensory information received from the user into an electrical signal. The input interface (211) can include various buttons, switches, and / or dials. For example, the input interface (211) can include a tact switch, a push switch, a slide switch, a toggle switch, a micro switch, a touch switch, a touch pad, a touch screen, a jog dial, and / or a microphone.

[0130] The output interface (212) can visually and / or audibly convey information related to the operation of the refrigerator (1) to the user. The output interface (212) can visually and / or audibly convey information related to the operation of the refrigerator (1) to the user. Information related to the operation of the refrigerator (1) can be output in the form of images, text, indicators, and / or voice. In addition, the output interface (212) can display a graphical user interface (GUI) that enables control of the refrigerator (1). That is, the display can display UI elements (User Interface Elements) such as icons. The output interface (212) can include at least one of a display and a speaker. The display can also be used as an input device, including a touch screen.

[0131] The communication interface (220) can connect to a user device (e.g., a mobile device, a smartphone) and / or a server via a network. The processor (320) can obtain various information, various signals, and / or various data from the user device and / or the server via the communication interface (220). For example, the communication interface (220) can receive a remote control signal from the user device. The processor (320) can obtain firmware and / or software for the operation of the refrigerator (1) from the server via the communication interface (220).

[0132] The communication interface (220) may include various communication circuits. The communication interface (220) may include wireless communication circuits and / or wired communication circuits. For example, a communication circuit supporting wireless communication methods such as wireless local area network (WLAN), home radio frequency (RF), infrared communication, ultra-wide band (UWB) communication, Wi-Fi, Bluetooth, and Zigbee may be provided.

[0133] The processor (320) can set the operating mode of the refrigerator (1) based on user input obtained through the user interface (210) or the user device. The operating mode of the refrigerator (1) can be provided in various ways. For example, the operating mode of the refrigerator (1) can include a refrigeration mode, a freezing mode, a non-freezing mode (supercooling mode), and a defrosting mode.

[0134] The operating mode of the refrigerator (1) can be set for each of the plurality of storage compartments (20). The operating modes set for each of the plurality of storage compartments (20) can be the same or different. For example, the refrigeration mode can be set for the upper storage compartment (22), and the freezing mode can be set for the lower storage compartments (23, 24).

[0135] The operation mode of the refrigerator (1) may be set for each of the plurality of storage spaces formed by the shelves (25), storage containers (26, 36) and / or electrodes (90). The operation modes set for each of the plurality of storage spaces may be the same or different. For example, a refrigeration mode may be set for each of the plurality of storage spaces divided by the shelves (25) and the first storage container (26) in the upper storage compartment (22). A non-freezing mode (supercooling mode) may be set for a storage space formed between the first electrode (90a) and the second electrode (90b) in the lower storage compartment (23, 24), and a freezing mode may be set for another storage space in the lower storage compartment (23, 24).

[0136] The target temperature of each of the plurality of storage rooms (20) and / or the target temperature of the food placed in each of the plurality of receiving spaces may be determined differently depending on the set operation mode. Since cooled air is supplied into the storage room (20), the temperature of the food placed in the storage room (20) generally follows the temperature of the storage room (20). However, when the food is placed between the plurality of electrodes (90), and an electric field is generated between the plurality of electrodes (90) to dielectrically heat the food, the temperature of the food may differ from the temperature of the storage room (20). Therefore, the temperature of the storage room (20) and the temperature of the food can be independently managed.

[0137] In the refrigeration mode and the freezing mode, the target temperature of the storage compartment (20) can be set to be equal to or lower than the target temperature of the food. For example, in the refrigeration mode, the target temperature of the food can be set to 3°C to 4°C. In the freezing mode, the target temperature of the food can be set to -18°C to -20°C. When dielectric heating using an electric field is performed, the temperature of the food can be maintained higher than the temperature of the storage compartment (20).

[0138] In the non-freezing mode (supercooling mode) and the defrosting mode, the target temperature of the storage chamber (20) can be set lower than the target temperature of the food. For example, when the freezing mode is set in the lower storage chamber (23, 24) and the non-freezing mode (supercooling mode) is set in the receiving space formed between the first electrode (90a) and the second electrode (90b), the processor (320) can set the target temperature of the lower storage chamber (23, 24) lower than the target temperature of the food placed between the first electrode (90a) and the second electrode (90b).

[0139] In the non-freezing mode (supercooling mode), the target temperature of the food can be set lower than the freezing point of the food. In the non-freezing mode (supercooling mode), the temperature of the food is lower than the freezing point, but the food can remain unfrozen. Typically, water molecules within the food combine with each other at temperatures lower than 0°C, resulting in freezing. However, when dielectric heating using an electric field is performed, even if the temperature of the storage compartment (20) where the food is placed is maintained at a temperature sufficiently low to freeze the food, the combination of water molecules within the food may be hindered, preventing freezing.

[0140] The defrosting mode is an operating mode for thawing frozen food. In this mode, the target temperature for the food can be set to room temperature (e.g., 20°C). When dielectric heating using an electric field is performed, the food can be thawed without damaging its tissue. Since thawing is possible within the refrigerator (1), the user can omit the process of separately defrosting the food after removing it from the refrigerator (1). This enhances user convenience.

[0141] The components of the refrigerator (1) electrically connected to the control unit (300) and / or the processor (320) are not limited to those illustrated. The refrigerator (1) may further include other components in addition to the described components.

[0142] The processor (320) can set the first target temperature of the storage compartment (20) and the second target temperature of the food placed between the plurality of electrodes (90) according to the operation mode. The processor (320) can control the compressor (70) so that the temperature of the storage compartment (20) is maintained at the first target temperature. The processor (320) can control at least one voltage control circuit (170, 180) and a frequency control circuit (190) based on the first target temperature of the storage compartment (20) and the second target temperature of the food.

[0143] For example, the processor (320) can adjust the reference voltage applied to at least one voltage control circuit (170, 180), the on / off duty ratio of the frequency control circuit (190), and / or the frequency of the switching signal generated by the frequency control circuit (190) based on the first target temperature of the storage room (20) and the second target temperature of the food. The processor (320) can set the reference voltage applied to at least one voltage control circuit (170, 180), the on / off duty ratio of the frequency control circuit (190), and / or the frequency of the switching signal generated by the frequency control circuit (190) to be higher as the second target temperature of the food is set higher.

[0144] To achieve a non-frozen state (i.e., a supercooled state) of food, the electric field applied to the food must be precisely controlled. Since the temperature and impedance of the food are affected by various factors, such as the type of food, the size of the food, the amount of water contained in the food, and the temperature of the storage chamber (20) in which the food is placed, it is difficult to achieve a non-frozen state of the food unless the electric field applied to the food is precisely controlled.

[0145] The disclosed refrigerator (1) can use a circuit system capable of dielectrically heating food to make food non-frozen (supercooled) and maintain the non-frozen state of the food. For example, the processor (320) of the refrigerator (1) can identify the impedance change rate of the food placed between the first electrode (90a) and the second electrode (90b) based on the output voltage and output current periodically detected by the voltage current detector (160). Based on the impedance change rate of the food, the processor (320) can adjust the reference voltage applied to at least one voltage control circuit (170, 180), the on / off duty ratio of the frequency control circuit (190), and / or the frequency of the switching signal generated by the frequency control circuit (190). Through this, the refrigerator (1) can maintain the non-frozen (supercooled) state of the food. Accordingly, long-term storage of the food can be possible without deterioration in the quality of the food.

[0146] When the impedance change rate of the food is less than or equal to a threshold value after the operation of the compressor (70) begins, the processor (320) can apply a reference voltage to at least one voltage control circuit (170, 180) to generate an electric field between the first electrode (90a) and the second electrode (90b). At this time, the processor (320) can set the on / off duty ratio of the frequency control circuit (190) to a reference duty ratio (e.g., 100%) and set the frequency of the switching signal to the reference frequency.

[0147] The processor (320) can adjust the reference voltage applied to at least one voltage control circuit (170, 180) if the impedance change rate of the food is greater than or equal to a reference value. The processor (320) can adjust the on / off duty ratio of the frequency control circuit (190) if the impedance change rate of the food is less than the reference value. In addition, the processor (320) can further adjust the frequency of the switching signal generated by the frequency control circuit (190) if the impedance change rate of the food is less than the reference value. Here, the reference value may be referred to as a 'first reference value'. The first reference value may be less than a threshold value.

[0148] The processor (320) may reduce the reference voltage applied to at least one voltage control circuit (170, 180) so that the input voltage of the RF power supply (140) decreases based on a decrease in the impedance change rate of the food. The processor (320) may reduce the on / off duty ratio of the frequency control circuit (190) based on a decrease in the impedance change rate of the food. In addition, the processor (320) may also reduce the frequency of the switching signal based on a decrease in the impedance change rate of the food.

[0149] The processor (320) can maintain the on-off duty ratio and / or the frequency of the switching signal of the frequency control circuit (190) constant based on the fact that the impedance change rate of the food is within the error range of the second reference value that is smaller than the first reference value. If the impedance change rate of the food is within the error range of the second reference value, it can indicate that the food is in a non-frozen state. Therefore, it is preferable to maintain the on-off duty ratio and / or the frequency of the switching signal of the frequency control circuit (190) constant in order to maintain the non-frozen state of the food.

[0150] The processor (320) can obtain food information corresponding to food identified by the food sensor (93) from the memory (310) or the user device and electric field control information corresponding to the food information. Based on the electric field control information, the processor (320) can determine a reference voltage applied to at least one voltage control circuit (170, 180), an on / off duty ratio of the frequency control circuit (190), and / or a frequency of a switching signal generated by the frequency control circuit (190).

[0151] The disclosed refrigerator (1) can directly and precisely control the dielectric heating energy supplied to food by controlling at least one voltage control circuit (170, 180) for controlling the input voltage of the RF power supply unit (140) and a frequency control circuit (190) for generating a switching signal for turning the RF power supply unit on or off.

[0152] Fig. 4 illustrates a circuit system for genetically heating food according to one embodiment. Figs. 5 and 6 illustrate detailed circuit structures of the circuit system illustrated in Fig. 4.

[0153] Referring to FIGS. 4, 5, and 6, an EMI filter (110) is connected to a commercial power source (AC) and can remove noise from AC power supplied from the commercial power source (AC). The EMI filter (110) can provide AC power with noise removed to a power factor correction circuit (120). The EMI filter (110) can be provided as a circuit in which various elements are connected in parallel and / or in series. For example, the EMI filter (110) can include a plurality of capacitors (C1, C2) connected in parallel, a plurality of inductors (L1, L2) implementing a transformer, and a plurality of diodes (D1, D2, D3, D4) forming a bridge. The circuit structure of the EMI filter (110) is not limited to that illustrated. The circuit structure of the EMI filter (110) can be provided in various ways depending on the design.

[0154] The power factor correction circuit (120) can compensate for the power factor of the AC power provided from the EMI filter (110). The power factor correction circuit (120) can provide the power with the power factor compensated to the DC converter (130). The power factor correction circuit (120) can be provided as a circuit in which various elements are connected in parallel and / or in series. For example, the power factor correction circuit (120) can include a plurality of electrolytic capacitors (Cpf1, Cpf2), an inductor (Lpf), a diode (Dpf), and a switching element (SW_pf). The switching element (SW_pf) can correspond to a transistor. The transistor can allow or block the flow of current depending on the application of voltage. The switching element (SW_pf) of the power factor correction circuit (120) can be referred to as a 'first switching element'. The circuit structure of the power factor correction circuit (120) is not limited to that illustrated. The circuit structure of the power factor compensation circuit (120) can be designed in various ways.

[0155] The DC converter (130) can convert the power output from the power factor correction circuit (120) into DC power. The DC converter (130) can transmit the converted DC power to the RF power supply (140). The DC converter (130) can be provided as a circuit in which various elements are connected in parallel and / or in series. For example, the DC converter (130) can include a switching element (SW_dc), an inductor (Ldc), and a diode (Ddc). The switching element (SW_dc) can correspond to a transistor. The switching element (SW_dc) and the inductor (Ldc) can be connected in series. The diode (Ddc) can be connected to a connection node of the switching element (SW_dc) and the inductor (Ldc). The switching element (SW_dc) of the DC converter (130) can be referred to as a 'second switching element'. The circuit structure of the DC converter (130) is not limited to that illustrated. The circuit structure of the DC converter (130) can be designed in various ways depending on the design.

[0156] The first voltage control circuit (170) is connected to the output terminal of the DC converter (130) and can adjust the input voltage of the RF power supply unit (140) under the control of the control unit (300). The first voltage control circuit (170) may be provided as a circuit in which various elements are connected in parallel and / or in series. For example, the first voltage control circuit (170) may include resistors (R1, R2, R3), a capacitor (Cdc), and an operational amplifier (OP-AMP) (OP1).

[0157] One end of a first resistor (R1) may be connected to one end of an inductor (Ldc) included in a DC converter (130), and the other end of the first resistor (R1) may be connected to a second resistor (R2). A minus (-) input terminal of an operational amplifier (OP1) may be connected to a connection node of the first resistor (R1) and the second resistor (R2). A plus (+) input terminal of the operational amplifier (OP1) may be connected to a control unit (300). An output terminal of the operational amplifier (OP1) may be connected to one end of a third resistor (R3) and a capacitor (Cdc) connected in parallel. The third resistor (R3) and the capacitor (Cdc) connected in parallel may correspond to a compensation circuit for ensuring the stability of the circuit. The other end of the third resistor (R3) and the capacitor (Cdc) connected in parallel may be connected to a switching element (SW_dc) of the DC converter (130). The circuit structure of the first voltage control circuit (170) is not limited to that illustrated.

[0158] The control unit (300) controls the first voltage control circuit (170) to control the input voltage (V) of the RF power supply unit (140). PA ) can be adjusted. The input voltage (V) of the RF power supply unit (140) PA ) may be referred to as the output voltage of the DC converter (130). The processor (320) adjusts the reference voltage applied to the first voltage control circuit (170) to adjust the input voltage (V) of the RF power supply (140). PA) can be controlled. The switching element (SW_dc) of the DC converter (130) can be controlled by a voltage signal output from the first voltage control circuit (170). The reference voltage applied to the first voltage control circuit (170) can be referred to as a 'first reference voltage'.

[0159] When the reference voltage applied to the plus (+) input terminal of the operational amplifier (OP1) is changed, the voltage applied to the minus (-) input terminal of the operational amplifier (OP1) may be changed. When the voltage applied to the minus (-) input terminal of the operational amplifier (OP1) is changed and the switching element (SW_dc) of the DC converter (130) is controlled, the input voltage (V) of the RF power supply (140) is changed according to the voltage distribution of the first resistor (R1) and the second resistor (R2). PA ) can be changed. The disclosed refrigerator (1) has an input voltage (V) of the RF power supply unit (140) PA ) can be adjusted to control the intensity of the electric field generated between the plurality of electrodes (90). When the reference voltage applied to the first voltage control circuit (170) increases, the input voltage (V) of the RF power supply unit (140) PA ) increases, and the strength of the electric field may also increase.

[0160] The RF power supply unit (140) may be provided as a circuit including various elements for generating an RF signal. For example, the RF power supply unit (140) may include an electrolytic capacitor (Cpa11), a capacitor (Cpa12), a plurality of inductors (Lpa11, Lpa12), and a switching element (SW_pa1). The electrolytic capacitor (Cpa11) may connect the Vpa node and the ground (GND). The switching element (SW_pa1) and the inductor (Lpa11) may be connected in series between the Vpa node and the ground (GND). In addition, the inductor (Lpa12) and the capacitor (Cpa12) connected in series may be arranged between the N1 node connecting the switching element (SW_pa1) and the inductor (Lpa11) and the impedance matching circuit (150). The switching element (SW_pa1) of the RF power supply unit (140) may be referred to as a ‘third switching element’.

[0161] The switching element (SW_pa1) of the RF power supply unit (140) may correspond to a transistor. The RF power supply unit (140) may be activated (ON) or deactivated (OFF) depending on the operation of the switching element (SW_pa1). The operation of the RF power supply unit (140) may be controlled depending on the switching signal (VG) applied to the switching element (SW_pa1). When the switching element (SW_pa1) is turned on, the operation of the RF power supply unit (140) may be activated. When the switching element (SW_pa1) is turned off, the operation of the RF power supply unit (140) may be deactivated.

[0162] The frequency control circuit (190) can generate a switching signal (VG) to turn on or off the RF power supply unit (140). The frequency control circuit (190) can be electrically connected to the control unit (300) and can output a switching signal (VG) to control the operation of the RF power supply unit (140) according to the control of the control unit (300). The switching signal (VG) can be output as a sine wave signal. The frequency control circuit (190) can include a voltage controlled oscillator (VCO).

[0163] The control unit (300) can input an activation signal (EN) to turn on the frequency control circuit (190) to the frequency control circuit (190). The frequency control circuit (190) can be turned on or off based on whether the activation signal (EN) is input. When the activation signal (EN) is input to the frequency control circuit (190), the frequency control circuit (190) is turned on and a switching signal can be output. The switching signal can be input to the switching element (SW_pa1) of the RF power supply unit (140). The switching element (SW_pa1) of the RF power supply unit (140) can be repeatedly turned on and off according to the switching signal. When the activation signal (EN) is not input to the frequency control circuit (190), the frequency control circuit (190) is turned off and the switching signal is not generated.

[0164] The control unit (300) may input an activation signal (EN) to the frequency control circuit (190) at a high level (1) or a low level (0). If the activation signal (EN) is 1, the frequency control circuit (190) may be turned on. If the activation signal (EN) is 0, the frequency control circuit (190) may be turned off.

[0165] The control unit (300) can periodically input an activation signal (EN). The control unit (300) can adjust the on / off duty ratio of the frequency control circuit (190) by adjusting the length of time for which the activation signal (EN) is maintained at a high level for one cycle. The on / off duty ratio of the frequency control circuit (190) can be defined as the on time ratio of the frequency control circuit (190) for one cycle. As the on / off duty ratio of the frequency control circuit (190) increases, the dielectric heating energy supplied to the food can increase.

[0166] In addition, the control unit (300) can adjust the frequency of the switching signal generated by the frequency control circuit (190). The frequency of the switching signal may also be referred to as a 'switching frequency'. The control unit (300) can input a frequency selection signal (FS) to the frequency control circuit (190) to adjust the frequency of the switching signal. The frequency of the switching signal can be determined based on the frequency selection signal (FS). When the frequency of the switching signal increases, the period of the switching signal shortens, and the switching speed of the switching element (SW_pa1) may increase. When the switching speed of the switching element (SW_pa1) increases, the dielectric heating energy supplied to the food may increase. Conversely, when the frequency of the switching signal decreases, the period of the switching signal lengthens, and the switching speed of the switching element (SW_pa1) may decrease. When the switching speed of the switching element (SW_pa1) decreases, the dielectric heating energy supplied to the food may decrease.

[0167] The impedance matching circuit (150) may be provided as a circuit in which a plurality of inductors (L), a plurality of capacitors (C), and a plurality of switches (S1, S2, S3, S4, S5, S6, S7, S8, S9) are connected in series and / or in parallel. The plurality of switches (S1, S2, S3, S4, S5, S6, S7, S8, S9) included in the impedance matching circuit (150) may be opened or closed under the control of the control unit (300). Impedance matching may be performed as the plurality of switches (S1, S2, S3, S4, S5, S6, S7, S8, S9) are controlled. The impedance matching circuit (150) is exemplified as including three inductors (L) connected in parallel, three capacitors (C) connected in parallel, and nine switches, but is not limited thereto. The structure of the impedance matching circuit (150) can be varied in various ways depending on the design. The control unit (300) can perform impedance matching corresponding to changes in the impedance of food by controlling the on-off of each of the multiple switches (S1, S2, S3, S4, S5, S6, S7, S8, S9).

[0168] Fig. 7 illustrates a circuit system for genetically heating food according to one embodiment. Fig. 8 illustrates a detailed circuit structure of the circuit system illustrated in Fig. 7.

[0169] Referring to FIGS. 7 and 8, the refrigerator (1) may include a second voltage control circuit (180) connected to the output terminal of the power factor correction circuit (120). Comparing FIGS. 4 and 7, the positions of the voltage control circuits are different. In FIG. 4, the first voltage control circuit (170) is connected to the output terminal of the DC converter (130), and in FIG. 7, the second voltage control circuit (180) is connected to the output terminal of the power factor correction circuit (120).

[0170] The EMI filter (110), power factor compensation circuit (120), DC converter (130), RF power supply (140), impedance matching circuit (150), voltage current detector (160), and frequency control circuit (190) illustrated in FIGS. 7 and 8 are identical to those described in FIGS. 4, 5, and 6.

[0171] The circuit structure of the second voltage control circuit (180) may be provided in the same manner as the circuit structure of the first voltage control circuit (170). The second voltage control circuit (180) may be provided as a circuit in which various elements are connected in parallel and / or in series. For example, the second voltage control circuit (180) may include resistors (R1, R2, R3), a capacitor (Cdc), and an operational amplifier (OP-AMP) (OP1).

[0172] In Fig. 8, one end of a first resistor (R1) may be connected to one end of a diode (Dpf) included in a power factor correction circuit (120), and the other end of the first resistor (R1) may be connected to a second resistor (R2). A minus (-) input terminal of an operational amplifier (OP1) may be connected to a connection node of the first resistor (R1) and the second resistor (R2). A plus (+) input terminal of the operational amplifier (OP1) may be connected to a control unit (300). An output terminal of the operational amplifier (OP1) may be connected to one end of a third resistor (R3) and a capacitor (Cdc) connected in parallel. The third resistor (R3) and capacitor (Cdc) connected in parallel may correspond to a compensation circuit for ensuring the stability of the circuit. The other end of the third resistor (R3) and capacitor (Cdc) connected in parallel can be connected to the switching element (SW_pf) of the power factor correction circuit (120). The circuit structure of the second voltage control circuit (180) is not limited to that illustrated.

[0173] The second voltage control circuit (180) is connected to the output terminal of the power factor correction circuit (120) and can control the input voltage of the DC converter (130). When the input voltage of the DC converter (130) changes, the output voltage of the DC converter (130) changes, so that the input voltage (V) of the RF power supply (140) PA ) can be changed. In other words, the control unit (300) controls the second voltage control circuit (180) to control the input voltage (V) of the RF power supply unit (140). PA ) can be controlled. The control unit (300) controls the reference voltage applied to the second voltage control circuit (180) to control the input voltage (V) of the RF power supply unit (140). PA ) can be adjusted.

[0174] The switching element (SW_pf) of the power factor compensation circuit (120) can be controlled by a voltage signal output from the second voltage control circuit (180). The reference voltage applied to the second voltage control circuit (180) can be referred to as a 'second reference voltage'.

[0175] When the reference voltage applied to the plus (+) input terminal of the operational amplifier (OP1) is changed, the voltage applied to the minus (-) input terminal of the operational amplifier (OP1) may be changed. When the voltage applied to the minus (-) input terminal of the operational amplifier (OP1) is changed and the switching element (SW_pf) of the power factor correction circuit (120) is controlled, the input voltage of the DC converter (130) may be changed according to the voltage distribution of the first resistor (R1) and the second resistor (R2). The disclosed refrigerator (1) can control the intensity of the electric field generated between the plurality of electrodes (90) by controlling the input voltage of the DC converter (130). When the reference voltage applied to the second voltage control circuit (180) increases, the input voltage of the DC converter (130) may increase. When the input voltage of the DC converter (130) increases, the input voltage (V) of the RF power supply unit (140) PA ) increases, and the strength of the electric field may increase.

[0176] FIG. 9 illustrates a circuit system for genetically heating food according to one embodiment.

[0177] Referring to Fig. 9, the refrigerator (1) may include a first voltage control circuit (170) connected to the output terminal of the DC converter (130) and a second voltage control circuit (180) connected to the output terminal of the power factor correction circuit (120). The circuit structure of the first voltage control circuit (170) is the same as that described in Figs. 4 and 5. The circuit structure of the second voltage control circuit (180) is the same as that described in Figs. 7 and 8.

[0178] The EMI filter (110), power factor compensation circuit (120), DC converter (130), RF power supply (140), impedance matching circuit (150), voltage current detector (160), and frequency control circuit (190) illustrated in FIG. 9 are the same as those described in FIGS. 4, 5, and 6.

[0179] As described above, the processor (320) of the refrigerator (1) can control the first voltage control circuit (170) to adjust the output voltage of the DC converter (130). In addition, the processor (320) can control the second voltage control circuit (180) to adjust the input voltage of the DC converter (130). When the refrigerator (1) includes both the first voltage control circuit (170) and the second voltage control circuit (180), the input voltage (V) of the RF power supply (140) PA ) can be controlled over a wider range. In other words, by using both the first voltage control circuit (170) and the second voltage control circuit (180), the input voltage (V) applied to the RF power supply unit (140) PA ) can increase the control range.

[0180] FIG. 10 illustrates an example of a switching signal output by a frequency control circuit according to one embodiment.

[0181] Referring to the graph (900) of FIG. 10, the processor (320) of the refrigerator (1) can input an activation signal (EN) to turn on the frequency control circuit (190) to the frequency control circuit (190). The frequency control circuit (190) can be turned on or off based on whether or not the activation signal (EN) is input.

[0182] When an activation signal (EN) is input to the frequency control circuit (190), the frequency control circuit (190) is turned on, and a switching signal (VG) can be output. The switching signal (VG) can be input to the RF power supply unit (140). The RF power supply unit (140) can be repeatedly turned on and off according to the switching signal (VG). When the activation signal (EN) is not input to the frequency control circuit (190), the frequency control circuit (190) is turned off, and the switching signal (VG) is not output. When the switching signal (VG) is not output from the frequency control circuit (190), the RF power supply unit (140) can be turned off.

[0183] The processor (320) may input an activation signal (EN) to the frequency control circuit (190) at a high level (1) or a low level (0). If the activation signal (EN) is 1, the frequency control circuit (190) may be turned on. If the activation signal (EN) is 0, the frequency control circuit (190) may be turned off.

[0184] The processor (320) can periodically input an activation signal (EN). The processor (320) can adjust the on / off duty ratio of the frequency control circuit (190) by adjusting the length of time for which the activation signal (EN) is maintained at a high level for one period. The on / off duty ratio of the frequency control circuit (190) can be defined as the ratio of the on time of the frequency control circuit (190) for one period. As the on / off duty ratio of the frequency control circuit (190) increases, the dielectric heating energy supplied to the food can increase. In order to reduce switching loss, the on / off period of the frequency control circuit (190) can be determined as an integer multiple of the period of the switching signal (VG) generated by the frequency control circuit (190).

[0185] FIG. 11 is an example of a graph showing changes in temperature of food and changes in food impedance in a non-freezing mode according to one embodiment.

[0186] When food is cooled, the cooling rate of the food may not be constant. In other words, the temperature of the food may not change at a constant rate as it cools. For example, the temperature of room temperature food may decrease nonlinearly over time after being placed in a refrigerator (1). The temperature of the food may be inversely proportional to the impedance of the food. As the temperature of the food decreases, the kinetic energy of water molecules and dissolved ions decreases, and the mobility of ions decreases, making charge transfer more difficult. This may result in a decrease in electrical conductivity and an increase in impedance. Until the temperature and impedance of the food reach equilibrium, the rate of change in the temperature of the food and the rate of change in the impedance of the food may not be constant.

[0187] Since the temperature and impedance of food are affected by various factors such as the type of food, the size of the food, the amount of water contained in the food, and the temperature of the storage compartment (20) in which the food is placed, it is difficult to keep the food in a non-frozen state unless the electric field applied to the food is precisely controlled. Even if the food enters a non-frozen state, the non-frozen state can be broken due to the various factors described above. If the non-frozen state is broken, the food is frozen and cannot return to the non-frozen state. Therefore, to stably maintain the non-frozen state of the food, it is necessary to precisely control the electric field applied to the food. The refrigerator (1) can control the electric field applied to the food by controlling the RF power supplied to the electrode (90).

[0188] In Fig. 11, food is placed between the first electrode (90a) and the second electrode (90b), and the operation mode of the receiving space and / or storage room (20) where the food is placed is described as a non-freezing mode. Referring to the graph (1000) of Fig. 11, if the food successfully enters the non-freezing state, the temperature (Ft) and impedance (It) of the food may appear as a 'solid line'. If the food fails to enter the non-freezing state, the temperature and impedance of the food may appear as a 'dotted line'. The impedance graph may represent the absolute value of the impedance.

[0189] Referring to the graph (1000) of Fig. 11, cooling of food may begin from time t0. The refrigerator (1) may operate the compressor (70) to cool the food. The temperature of the food may rapidly decrease nonlinearly from time t0 and reach a critical temperature (T_th) higher than the reference temperature (T_ref) at time t1. The reference temperature (T_ref) may correspond to the freezing point of the food. The impedance of the food may increase from time t0 and reach the critical impedance (I_th) at time t1.

[0190] If the food is supplied with dielectric heating energy at the same time as the food begins to cool, the cooling of the food may be delayed or the food may not be cooled at all. Therefore, the refrigerator (1) may not apply an RF signal to the plurality of electrodes (90) from time t0 to time t1.

[0191] The impedance change rate of food can be explained by the slope of the impedance graph. The impedance change rate of food at time t1 can correspond to a threshold value (di_th). When the impedance change rate of food is less than or equal to the threshold value (di_th), the refrigerator (1) can apply a reference voltage to at least one voltage control circuit (170, 180) to generate an electric field between a plurality of electrodes (90). When the electric field is applied to the food, dielectric heating energy is supplied to the food, and the food can be heated. Therefore, the cooling rate of the food can be slowed down. By reducing the cooling rate of the food, it can be easier to make the food into a non-frozen (supercooled) state.

[0192] At time t2, the temperature of the food reaches the reference temperature (T_ref), and the impedance of the food reaches the reference impedance (I_ref). The reference temperature (T_ref) can correspond to the freezing point of the food. The rate of change in the impedance of the food at time t2 can correspond to the reference value (di_ref).

[0193] The refrigerator (1) can adjust the reference voltage applied to at least one voltage control circuit (170, 180) based on the impedance change rate of the food until the time point t2 when the impedance change rate of the food reaches the reference value (di_ref). In other words, the refrigerator (1) can adjust the reference voltage applied to at least one voltage control circuit (170, 180) when the impedance change rate of the food is greater than or equal to the reference value (di_ref). The refrigerator (1) can reduce the reference voltage applied to at least one voltage control circuit (170, 180) so that the input voltage of the RF power supply unit (140) decreases based on a decrease in the impedance change rate of the food. The reference value (di_ref) regarding the impedance change rate of the food can be set to be smaller than a threshold value (di_th).

[0194] Since the RF power control range becomes large in a section where the temperature change and the impedance change of the food are relatively large (e.g., from time t1 to time t2), controlling the input voltage of the RF power supply unit (140) is efficient for controlling the temperature and impedance of the food. The refrigerator (1) can control the input voltage of the RF power supply unit (140) by controlling the reference voltage applied to at least one voltage control circuit (170, 180) from time t1 to time t2. The section from time t1 to time t2 may also be referred to as a 'first control section'.

[0195] The refrigerator (1) can set the on / off duty ratio of the frequency control circuit (190) to a reference duty ratio (e.g., 100%) from time t1 to time t2, and set the frequency of the switching signal to the reference frequency. When the on / off duty ratio of the frequency control circuit (190) is set to the reference duty ratio, the frequency control circuit (190) can maintain an on state and continuously output a switching signal.

[0196] From time t2 when the temperature of the food reaches the reference temperature (T_ref), the changes in moisture content and permittivity of the food may decrease. From time t2, the rate of change in temperature of the food and the rate of change in impedance of the food may decrease significantly. In a section where the temperature change of the food and the impedance change of the food are relatively small (e.g., from time t2 to time t3), it is necessary to precisely control the dielectric heating energy supplied to the food rather than controlling the size of the RF power applied to the food. The refrigerator (1) may control the on / off duty ratio of the frequency control circuit (190) to precisely control the dielectric heating energy. The refrigerator (1) may maintain the reference voltage applied to at least one voltage control circuit (170, 180) constant from time t2. The section from time t2 to time t3 may be referred to as a 'second control section'.

[0197] The refrigerator (1) can adjust the on / off duty ratio of the frequency control circuit (190) when the impedance change rate of the food is less than the reference value (di_ref). The refrigerator (1) can reduce the on / off duty ratio of the frequency control circuit (190) based on a decrease in the impedance change rate of the food. When the on / off duty ratio of the frequency control circuit (190) reduces, the on time of the RF power supply unit (140) can reduce and the off time can increase. The reference value (di_ref) at time t2 with respect to the impedance change rate of the food can be referred to as a 'first reference value'.

[0198] The impedance change rate of the food gradually decreases and may reach a second reference value (e.g., 0) at time t3. The second reference value regarding the impedance change rate of the food may be set to be smaller than the first reference value (di_ref). If the impedance change rate of the food is within the error range of the second reference value (e.g., 0), the refrigerator (1) may determine that the food has entered a non-frozen state. Based on the fact that the impedance change rate of the food is within the error range of the second reference value (e.g., 0), the refrigerator (1) may constantly maintain the on-off duty ratio of the frequency control circuit (190) and / or the frequency of the switching signal.

[0199] In this way, by operating the compressor (70) to cool the food and appropriately supplying dielectric heating energy to the food, it is possible to store the food in a non-freezing (supercooling) state, where the temperature of the food is lower than the freezing point but the food is not frozen. In addition, by utilizing the thermal equilibrium between the cold air supplied to the storage compartment (20) and the dielectric heating energy, the temperature of the storage compartment (20) can be lowered further while storing the food in a non-freezing (supercooling) state. The refrigerator (1) can maintain good quality of the food by suppressing spoilage of the food and storing the food in a non-freezing (supercooling) state at the same time.

[0200] Meanwhile, the refrigerator (1) can obtain food information corresponding to food identified by the food sensor (93) from the memory (310) or the user device and electric field control information corresponding to the food information. The refrigerator (1) can adjust the reference voltage applied to at least one voltage control circuit (170, 180) in the first control section based on the electric field control information. The refrigerator (1) can adjust the on / off duty ratio of the frequency control circuit (190) in the second control section based on the electric field control information.

[0201] If no dielectric heating energy is supplied to the food, it will continue to cool, and its temperature may drop to the critical temperature (T_lim). From the point at which the temperature reaches the critical temperature (T_lim) (e.g., at time t3), a state change occurs in the food, leading to freezing. While this state change occurs, the temperature can be maintained at the freezing point (T_ref). When this state change occurs, the food's impedance also increases significantly and can remain constant.

[0202] FIG. 12 is another example of a graph showing temperature changes of food in a non-freezing mode according to one embodiment.

[0203] The graph (1100) of Fig. 12 represents the temperature (Ft) of food and the temperature (St) of the storage compartment (20). Referring to the graph (1100) of Fig. 12, the refrigerator (1) can set the target temperature (T_set) of the storage compartment (20) according to the operation mode of the storage compartment (20). For example, the operation mode of the storage compartment (20) may be a non-freezing mode, and the target temperature (T_set) of the storage compartment (20) may be -18°C.

[0204] The refrigerator (1) can also stepwise adjust the dielectric heating energy supplied to the food to keep the food in a non-frozen state. For example, if the refrigerator (1) cannot obtain electric field control information, it can stepwise adjust the on-off duty ratio of the frequency control circuit (190) according to the temperature of the food.

[0205] The refrigerator (1) can operate the compressor (70) to cool the food. The refrigerator (1) can control the compressor (70) to maintain the temperature of the storage compartment (20) at a target temperature (T_set). In addition, the refrigerator (1) can apply a reference voltage to at least one voltage control circuit (170, 180) to generate an electric field between a plurality of electrodes (90) based on the temperature of the food.

[0206] The refrigerator (1) can gradually reduce the on-off duty ratio of the frequency control circuit (190) from the time ta when the temperature of the food reaches the freezing point (T_fp). For example, the refrigerator (1) can determine the on-off duty ratio of the frequency control circuit (190) as the first duty ratio from the time ta to the time tb. The refrigerator (1) can change the on-off duty ratio of the frequency control circuit (190) to the second duty ratio at the time tb, and change the on-off duty ratio of the frequency control circuit (190) to the third duty ratio at the time tc. The first duty ratio may be the largest, and the third duty ratio may be the smallest. The second duty ratio may be smaller than the first duty ratio and larger than the third duty ratio. As the on-off duty ratio of the frequency control circuit (190) gradually reduces, the dielectric heating energy supplied to the food may also gradually reduce.

[0207] When the food enters a non-frozen state, the refrigerator (1) can maintain the on / off duty ratio of the frequency control circuit (190) at a constant fourth duty ratio, which is lower than the third duty ratio. Accordingly, the food can be maintained in a non-frozen state. The temperature of the food can be maintained higher than the limit temperature (T_lim).

[0208] FIG. 13 is an example of a graph showing temperature changes of food in refrigeration mode in a refrigerator according to one embodiment.

[0209] Referring to the graph (1200) of Fig. 13, the operation mode of the storage space where food is placed may be set to a refrigeration mode, and the operation mode of the storage compartment (20) may be set to a freezing mode. The refrigerator (1) may operate the compressor (70) to maintain the temperature (St) of the storage compartment (20) at a first target temperature (T_set1). The refrigerator (1) may control the operation of the RF power supply unit (140) to converge the temperature (Ft) of the food to a second target temperature (T_set2). For example, the first target temperature (T_set1) may be -18°C, and the second target temperature (T_set2) may be 3°C.

[0210] In this way, the refrigerator (1) can refrigerate food even in a freezing environment where the food may be frozen by appropriately supplying genetic heating energy to the food.

[0211] Fig. 14 is an example of a graph showing temperature changes of food in a defrosting mode according to one embodiment.

[0212] Referring to the graph (1300) of Fig. 14, the operation mode of the storage space where food is placed may be set to a defrosting mode. The operation mode of the storage compartment (20) may be set to a freezing mode. The refrigerator (1) may operate the compressor (70) to maintain the temperature (St) of the storage compartment (20) at a first target temperature (T_set1). The refrigerator (1) may control the operation of the RF power supply unit (140) to converge the temperature (Ft) of the food to a second target temperature (T_set2). For example, the first target temperature (T_set1) may be -18°C, and the second target temperature (T_set2) may be 20°C. When the food is frozen, the temperature (Ft) of the food may be lower than the freezing point (T_ft). When an electric field is applied to the food, the food may be heated and the temperature (Ft) of the food may increase. Heating food can cause a phase change in the food (e.g., solid state -> liquid state).

[0213] In this way, the refrigerator (1) can thaw food even in a frozen environment where the food may be frozen by appropriately supplying genetic heating energy to the food.

[0214] Fig. 15 is a flowchart illustrating a method for controlling a refrigerator according to one embodiment.

[0215] Referring to FIG. 15, the processor (320) of the refrigerator (1) can operate the compressor (70) to supply refrigerant to the evaporator (81, 82) to cool the storage compartment (20) (1401). For example, the processor (320) can set a first target temperature of the storage compartment (20) according to the operating mode. The processor (320) can control the compressor (70) so that the temperature of the storage compartment (20) is maintained at the first target temperature.

[0216] A plurality of electrodes (90) may be arranged within the storage chamber (20). The plurality of electrodes (90) may be arranged parallel to each other and spaced apart from each other. For example, a first electrode (90a) and a second electrode (90b) may be arranged parallel to each other and spaced apart from each other within the storage chamber (20). Each of the first electrode (90a) and the second electrode (90b) may be included in a shelf. The first electrode (90a) and the second electrode (90b) may be fixed to the inner case (11) or may be provided to be detachable.

[0217] Food may be placed between the first electrode (90a) and the second electrode (90b). For example, the first electrode (90a) and the second electrode (90b) may divide the storage chamber (20) into a plurality of storage spaces. Food may be placed in the storage spaces between the first electrode (90a) and the second electrode (90b). A storage container (26, 36) containing food may also be placed between the first electrode (90a) and the second electrode (90b).

[0218] The processor (320) can detect the output voltage between the first electrode (90a) and the second electrode (90b) and the output current of the first electrode (90a) through the voltage / current detector (160) (1402). The processor (320) can control the voltage / current detector (160) to periodically detect the output voltage between the first electrode (90a) and the second electrode (90b) and the output current of the first electrode (90a). The voltage / current detector (160) can detect the output voltage between the first electrode (90a) and the second electrode (90b) and the output current of the first electrode (90a) at time intervals set by the processor (320).

[0219] The processor (320) can determine the impedance change rate of the food based on the output voltage and output current of the electrode (90) that are periodically detected (1403). The impedance change rate of the food can represent the amount of impedance change of the food per unit time. The impedance change rate of the food can be described by the slope of the impedance graph. The impedance of the food can vary depending on various factors such as the type of food, the size of the food, the amount of water contained in the food, and the temperature of the storage compartment (20) where the food is placed. For example, the higher the moisture content of the food, the lower the impedance of the food. Additionally, the lower the temperature of the food, the higher the impedance of the food. The impedance of the food can be inversely proportional to the temperature of the food. As the food cools, the impedance change rate of the food can gradually decrease. As the food cools, the impedance of the food can nonlinearly increase and then converge to a specific impedance.

[0220] The processor (320) can adjust the reference voltage applied to at least one voltage control circuit (170, 180) or the on / off duty ratio of the frequency control circuit (190) based on the impedance change rate of the food (1404). In addition, the processor (320) can also adjust the frequency of the switching signal generated by the frequency control circuit (190) based on the impedance change rate of the food. Through this, the refrigerator (1) can maintain the food in a non-frozen (supercooled) state. Accordingly, long-term storage of the food can be possible without deterioration in the quality of the food.

[0221] Fig. 16 is a flowchart explaining in more detail the control method of the refrigerator described in Fig. 15.

[0222] Referring to FIG. 16, the processor (320) of the refrigerator (1) can operate the compressor (70) to supply refrigerant to the evaporator (81, 82) to cool the storage compartment (20) (1501). The processor (320) can detect the output voltage between the first electrode (90a) and the second electrode (90b) and the output current of the first electrode (90a) through the voltage / current detector (160) (1502). The processor (320) can determine the impedance change rate of the food based on the output voltage and output current of the electrode (90) detected periodically (1503). Operations 1501, 1502, and 1503 correspond to operations 1401, 1402, and 1403 described in FIG. 15.

[0223] When the impedance change rate of the food is less than or equal to a threshold value after the cooling of the food begins, the processor (320) can apply a reference voltage to at least one voltage control circuit (170, 180) to generate an electric field between the first electrode (90a) and the second electrode (90b) (1504). At this time, the processor (320) can set the on / off duty ratio of the frequency control circuit (190) to a reference duty ratio (e.g., 100%) and set the frequency of the switching signal to the reference frequency. When the on / off duty ratio of the frequency control circuit (190) is set to the reference duty ratio, the frequency control circuit (190) can maintain an on state and continuously output the switching signal.

[0224] If the impedance change rate of the food is greater than the threshold value, the refrigerator (1) may not apply an RF signal to the first electrode (90a) and the second electrode (90b) to prevent cooling delay and / or cooling failure of the food.

[0225] When an electric field is applied to food, dielectric heating energy is supplied to the food, potentially heating it. This can slow down the cooling rate of the food. By slowing down the cooling rate, it becomes easier to achieve a non-freezing (supercooling) state.

[0226] The processor (320) can identify whether the impedance change rate of the food is greater than or equal to a first reference value (1505). If the impedance change rate of the food is greater than or equal to the first reference value, the processor (320) can adjust the reference voltage applied to at least one voltage control circuit (170, 180) (1506). The first reference value may be less than the threshold value described in operation 1504.

[0227] For example, the processor (320) may reduce the reference voltage applied to at least one voltage control circuit (170, 180) so that the input voltage of the RF power supply (140) decreases based on a decrease in the impedance change rate of the food. When the input voltage of the RF power supply (140) decreases, the intensity of the electric field generated between the first electrode (90a) and the second electrode (90b) may decrease. Since the control range of the RF power increases in a section where the temperature change of the food and the impedance change of the food are relatively large, controlling the input voltage of the RF power supply (140) is efficient for controlling the temperature of the food and the impedance of the food.

[0228] The processor (320) can adjust the on / off duty ratio of the frequency control circuit (190) if the impedance change rate of the food is less than the first reference value (1507). In addition, the processor (320) can further adjust the frequency of the switching signal generated by the frequency control circuit (190) if the impedance change rate of the food is less than the first reference value. The refrigerator (1) can maintain the reference voltage applied to at least one voltage control circuit (170, 180) constant while adjusting the on / off duty ratio of the frequency control circuit (190).

[0229] For example, the processor (320) may reduce the on / off duty ratio of the frequency control circuit (190) based on a decrease in the impedance change rate of the food. Additionally, the processor (320) may also reduce the frequency of the switching signal based on a decrease in the impedance change rate of the food.

[0230] As food cools, its moisture content and dielectric constant decrease. As food cools, its temperature change rate and impedance change rate also decrease. In areas where temperature and impedance changes are relatively small, it is necessary to precisely control the dielectric heating energy supplied to the food rather than simply adjusting the amount of RF power applied to the food. The refrigerator (1) can precisely control the dielectric heating energy by adjusting the on-off duty ratio of the frequency control circuit (190).

[0231] The processor (320) can identify whether the impedance change rate of the food is within the error range of the second reference value that is smaller than the first reference value (1508). Based on the fact that the impedance change rate of the food is within the error range of the second reference value that is smaller than the first reference value, the processor (320) can maintain the on / off duty ratio of the frequency control circuit (190) at a constant level (1509). In addition, the processor (320) can maintain the frequency of the switching signal generated by the frequency control circuit (190) at a constant level based on the fact that the impedance change rate of the food is within the error range of the second reference value. The second reference value regarding the impedance change rate of the food may correspond to 0.

[0232] If the impedance change rate of the food is within the error range of the second reference value, it can be indicated that the food is in a non-frozen state. Therefore, to maintain the non-frozen state of the food, it is desirable to keep the on / off duty ratio of the frequency control circuit (190) and / or the frequency of the switching signal constant.

[0233] In this way, by operating the compressor (70) to cool the food and appropriately supplying dielectric heating energy to the food, the food can be stored in a non-freezing (supercooling) state, with the temperature of the food lower than the freezing point but without freezing. The refrigerator (1) can maintain the good quality of the food by suppressing food spoilage and simultaneously storing the food in a non-freezing (supercooling) state.

[0234] FIG. 17 is a flowchart illustrating a method that can be added to the control method of a refrigerator described in FIG. 15.

[0235] Referring to FIG. 17, the processor (320) of the refrigerator (1) can obtain food information corresponding to food identified by the food sensor (93) from the memory (310) or the user device (1601). For example, the food information may include various information such as the type, size, volume, and / or quantity of the food.

[0236] The processor (320) can obtain electric field control information corresponding to food information from the memory (310) or the user device (1602). For example, the electric field control information may include the magnitude of the input voltage of the RF power supply (140) corresponding to the impedance value of the food and / or the impedance change rate of the food, and the on / off duty ratio of the RF power supply (140).

[0237] The processor (320) can adjust the reference voltage applied to at least one voltage control circuit (170, 180) or the on / off duty ratio of the frequency control circuit (190) based on the electric field control information (1603). In addition, the processor (320) can adjust the frequency of the switching signal generated by the frequency control circuit (190) based on the electric field control information.

[0238] In one embodiment, a refrigerator may include: a storage compartment; an evaporator for cooling the storage compartment; a compressor for supplying refrigerant to the evaporator; a first electrode disposed within the storage compartment; a second electrode disposed spaced apart from the first electrode within the storage compartment; an RF power supply unit for applying an RF signal to the first electrode and the second electrode; at least one voltage control circuit for controlling an input voltage of the RF power supply unit; a frequency control circuit for generating a switching signal for turning on or off the RF power supply unit; a voltage-current detector for detecting an output voltage between the first electrode and the second electrode and an output current of the first electrode; a memory for storing instructions; and at least one processor connected to the compressor, the at least one voltage control circuit, the frequency control circuit, the voltage-current detector, and the memory. When the above instructions are executed by the at least one processor, the refrigerator can operate the compressor to cool the storage compartment, identify an impedance change rate of food placed between the first electrode and the second electrode based on the output voltage and the output current periodically detected by the voltage / current detector, and adjust a reference voltage applied to the at least one voltage control circuit or an on / off duty ratio of the frequency control circuit based on the impedance change rate of the food.

[0239] When the above instructions are executed by the at least one processor, the refrigerator can adjust the reference voltage applied to the at least one voltage control circuit if the impedance change rate of the food is greater than or equal to a reference value, and can adjust the on / off duty ratio of the frequency control circuit if the impedance change rate of the food is less than the reference value.

[0240] When the above instructions are executed by the at least one processor, the refrigerator can reduce the reference voltage so that the input voltage decreases based on a decrease in the impedance change rate of the food, and reduce the on-off duty ratio of the frequency control circuit.

[0241] When the above instructions are executed by the at least one processor, the refrigerator can further adjust the frequency of the switching signal if the impedance change rate of the food is less than the reference value.

[0242] When the above instructions are executed by the at least one processor, the refrigerator can reduce the frequency of the switching signal based on a decrease in the impedance change rate of the food.

[0243] The above reference value may be a first reference value. When the instructions are executed by the at least one processor, the refrigerator may maintain the on / off duty ratio of the frequency control circuit at a constant level based on the impedance change rate of the food being within an error range of a second reference value that is smaller than the first reference value.

[0244] When the above instructions are executed by the at least one processor, the refrigerator may apply the reference voltage to the at least one voltage control circuit to generate an electric field between the first electrode and the second electrode if the impedance change rate of the food is less than or equal to a threshold value after the operation of the compressor starts. The threshold value may be greater than the reference value.

[0245] The refrigerator may further include a food sensor for identifying the food. When the instructions are executed by the at least one processor, the refrigerator may obtain food information corresponding to the identified food and electric field control information corresponding to the food information from a memory or a user device, and determine a reference voltage applied to the at least one voltage control circuit or an on / off duty ratio of the frequency control circuit based on the electric field control information.

[0246] The refrigerator may further include a DC converter for applying voltage to the RF power supply; and a power factor correction circuit for delivering power factor-compensated power to the DC converter. The at least one voltage control circuit may be connected to at least one of the DC converter and the power factor correction circuit.

[0247] A method for controlling a refrigerator, comprising: a storage compartment; an evaporator for cooling the storage compartment; a compressor for supplying refrigerant to the evaporator; a first electrode disposed within the storage compartment; a second electrode disposed spaced apart from the first electrode within the storage compartment; an RF power supply unit for applying an RF signal to the first electrode and the second electrode; a DC converter for applying voltage to the RF power supply unit; and a power factor correction circuit for transmitting power factor-compensated power to the DC converter, the method comprising: operating the compressor to supply refrigerant to the evaporator to cool the storage compartment; identifying an impedance change rate of food disposed between the first electrode and the second electrode based on an output voltage between the first electrode and the second electrode and an output current of the first electrode, which are periodically detected by a voltage / current detector; And, based on the impedance change rate of the food, it may include adjusting a reference voltage applied to at least one voltage control circuit for adjusting the input voltage of the RF power supply unit, or adjusting an on-off duty ratio of a frequency control circuit for generating a switching signal for turning the RF power supply unit on or off.

[0248] Adjusting the reference voltage or the on-off duty ratio may include adjusting the reference voltage applied to the at least one voltage control circuit when the impedance change rate of the food is greater than or equal to the reference value; and adjusting the on-off duty ratio of the frequency control circuit when the impedance change rate of the food is less than the reference value.

[0249] Adjusting the reference voltage may include reducing the reference voltage so that the input voltage decreases based on a decrease in the impedance change rate of the food. Adjusting the on-off duty ratio may include reducing the on-off duty ratio based on a decrease in the impedance change rate of the food.

[0250] The above control method may further include adjusting the frequency of the switching signal when the impedance change rate of the food is less than the reference value.

[0251] Adjusting the frequency of the switching signal may include reducing the frequency of the switching signal based on a decrease in the impedance change rate of the food.

[0252] The above reference value may be a first reference value. Adjusting the on-off duty ratio may include maintaining the on-off duty ratio of the frequency control circuit constant based on the impedance change rate of the food being within an error range of a second reference value that is smaller than the first reference value.

[0253] The control method may further include applying the reference voltage to the at least one voltage control circuit to generate an electric field between the first electrode and the second electrode when the impedance change rate of the food is less than or equal to a threshold value after the operation of the compressor begins. The threshold value may be greater than the reference value.

[0254] The control method may further include: identifying the food by a food sensor; and obtaining food information corresponding to the identified food and electric field control information corresponding to the food information from a memory or a user device. Adjusting the reference voltage or the on / off duty ratio may include determining the reference voltage applied to the at least one voltage control circuit or the on / off duty ratio of the frequency control circuit based on the electric field control information.

[0255] The disclosed refrigerator and its control method can directly and precisely control the temperature of food using dielectric heating.

[0256] The disclosed refrigerator and its control method can not only refrigerate and freeze food, but also maintain food in a non-frozen (supercooled) state and even thaw food. Furthermore, the disclosed refrigerator and its control method can also ripen food.

[0257] The disclosed refrigerator and its control method can maintain a non-frozen (supercooled) state of food, thereby enabling long-term storage of food without deterioration in quality of the food.

[0258] The disclosed refrigerator and its control method can defrost frozen food, so that when a user needs to cook frozen food, the food can be quickly provided in a cookable state.

[0259] Meanwhile, the disclosed embodiments may be implemented in the form of a storage medium storing computer-executable instructions. The instructions may be stored in the form of program code, and when executed by the processor (320), may generate program modules to perform the operations of the disclosed embodiments.

[0260] A device-readable storage medium may be provided in the form of a non-transitory storage medium. Here, the term "non-transitory storage medium" simply means a tangible device that does not contain signals (e.g., electromagnetic waves). This term does not distinguish between cases where data is permanently stored in the storage medium and cases where data is temporarily stored. For example, a "non-transitory storage medium" may include a buffer in which data is temporarily stored.

[0261] The methods according to various embodiments disclosed in this document may be provided as included in a computer program product. The computer program product may be traded as a product between a seller and a buyer. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., compact disc read-only memory (CD-ROM)), or may be distributed online (e.g., downloaded or uploaded) via 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., a downloadable app) may be temporarily stored or temporarily generated in a machine-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or an intermediary server.

[0262] The disclosed embodiments have been described with reference to the attached drawings as described above. Those skilled in the art will understand that the present invention can be implemented in forms other than the disclosed embodiments without altering the technical spirit or essential features of the present invention. The disclosed embodiments are illustrative and should not be construed as limiting.

Claims

1. Storage room; An evaporator for cooling the above storage chamber; A compressor that supplies refrigerant to the above evaporator; A first electrode placed within the storage chamber; A second electrode spaced apart from the first electrode within the storage chamber; An RF power supply unit that applies an RF signal to the first electrode and the second electrode; At least one voltage control circuit for regulating the input voltage of the RF power supply; A frequency control circuit for generating a switching signal for turning the RF power supply unit on or off; A voltage / current detector that detects an output voltage between the first electrode and the second electrode and an output current of the first electrode; Memory that stores instructions; and At least one processor connected to the compressor, the at least one voltage control circuit, the frequency control circuit, the voltage-current detector and the memory; When the above instructions are executed by the at least one processor, the refrigerator, Operate the compressor to cool the storage room, Identifying the impedance change rate of the food placed between the first electrode and the second electrode based on the output voltage and the output current periodically detected by the voltage and current detector, A refrigerator that controls the reference voltage applied to at least one voltage control circuit or the on / off duty ratio of the frequency control circuit based on the impedance change rate of the food.

2. In paragraph 1, When the above instructions are executed by the at least one processor, the refrigerator, If the impedance change rate of the above food is greater than or equal to the reference value, the reference voltage applied to at least one voltage control circuit is adjusted, A refrigerator that adjusts the on-off duty ratio of the frequency control circuit when the impedance change rate of the food is less than the reference value.

3. In paragraph 2, When the above instructions are executed by the at least one processor, the refrigerator, A refrigerator that reduces the reference voltage so that the input voltage decreases based on a decrease in the impedance change rate of the food, and reduces the on-off duty ratio of the frequency control circuit.

4. In paragraph 2, When the above instructions are executed by the at least one processor, the refrigerator, A refrigerator that further adjusts the frequency of the switching signal when the impedance change rate of the food is less than the reference value.

5. In paragraph 4, When the above instructions are executed by the at least one processor, the refrigerator, A refrigerator that reduces the frequency of the switching signal based on a decrease in the impedance change rate of the food.

6. In paragraph 2, The above reference value is the first reference value, When the above instructions are executed by the at least one processor, the refrigerator, A refrigerator that maintains the on-off duty ratio of the frequency control circuit constant based on the impedance change rate of the food being within the error range of a second reference value that is smaller than the first reference value.

7. In paragraph 2, When the above instructions are executed by the at least one processor, the refrigerator, After the operation of the compressor starts, if the impedance change rate of the food is less than or equal to a threshold value, the reference voltage is applied to the at least one voltage control circuit to generate an electric field between the first electrode and the second electrode, The above threshold value is greater than the above reference value.

8. In paragraph 1, Further comprising a food sensor for identifying the food; When the above instructions are executed by the at least one processor, the refrigerator, Obtain food information corresponding to the identified food and electric field control information corresponding to the food information from the memory or user device, A refrigerator that determines the reference voltage applied to at least one voltage control circuit or the on / off duty ratio of the frequency control circuit based on the electric field control information.

9. In paragraph 1, A DC converter for applying voltage to the RF power supply; and Further comprising a power factor compensation circuit for transmitting power factor-compensated power to the DC converter; At least one voltage control circuit is A refrigerator connected to at least one of the above DC converter and the above power factor correction circuit.

10. A control method performed by a refrigerator including a storage room, an evaporator for cooling the storage room, a compressor for supplying refrigerant to the evaporator, a first electrode disposed within the storage room, a second electrode disposed spaced apart from the first electrode within the storage room, an RF power supply unit for applying an RF signal to the first electrode and the second electrode, a DC converter for applying voltage to the RF power supply unit, and a power factor correction circuit for transmitting power factor-compensated power to the DC converter. Operate the compressor to supply refrigerant to the evaporator to cool the storage room; Identifying the impedance change rate of food placed between the first electrode and the second electrode based on the output voltage between the first electrode and the second electrode and the output current of the first electrode, which are periodically detected by the voltage current detector; and A method for controlling a refrigerator, comprising: adjusting a reference voltage applied to at least one voltage control circuit for controlling an input voltage of the RF power supply unit based on the impedance change rate of the food; or adjusting an on-off duty ratio of a frequency control circuit for generating a switching signal for turning the RF power supply unit on or off.

11. In paragraph 10, Adjusting the above reference voltage or adjusting the on / off duty ratio is If the impedance change rate of the food is greater than or equal to a reference value, the reference voltage applied to at least one voltage control circuit is adjusted; A method for controlling a refrigerator, comprising: adjusting the on / off duty ratio of the frequency control circuit when the impedance change rate of the food is less than the reference value.

12. In paragraph 11, Adjusting the above reference voltage is: reducing the reference voltage so that the input voltage decreases based on a decrease in the impedance change rate of the food; Adjusting the above on / off duty ratio is A method for controlling a refrigerator, comprising: reducing the on-off duty ratio based on a decrease in the impedance change rate of the food; 13. In paragraph 11, A method for controlling a refrigerator, further comprising: adjusting the frequency of the switching signal when the impedance change rate of the food is less than the reference value.

14. In paragraph 13, Controlling the frequency of the above switching signal is as follows: A method for controlling a refrigerator, comprising: reducing the frequency of the switching signal based on a decrease in the impedance change rate of the food; 15. In paragraph 11, The above reference value is the first reference value, Adjusting the above on / off duty ratio is A control method for a refrigerator, comprising: maintaining the on-off duty ratio of the frequency control circuit constant based on the impedance change rate of the food being within an error range of a second reference value that is smaller than the first reference value.

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