Dryer and control method thereof

Abstract

A dryer, according to one embodiment, may comprise: an RF power unit including a plurality of transistors connected in parallel to each other, and generating an RF signal to be applied to a plurality of electrodes; a feedback circuit including an error amplifier that amplifies an error voltage between an output terminal voltage of the plurality of transistors and a reference voltage, and an oscillator that outputs an input signal of a frequency corrected on the basis of the error voltage; and a plurality of gate drivers amplifying the input signal of the corrected frequency outputted from the feedback circuit and applying the amplified input signal to the plurality of transistors.

Description

Dryer and method of controlling the same

[0001] The disclosed invention relates to a dryer for drying a drying object using a genetic heating device and a method for controlling the same.

[0002] Typically, dryers use hot air drying to dry items. Hot air drying uses indirect heating, removing moisture through heated air. This reduces efficiency and can lead to longer drying times.

[0003] To improve drying performance, methods utilizing electromagnetic waves have been attempted in dryers. One such method utilizes a dielectric heating device, which applies an electric field to the object to be dried and exploits the frictional heat loss generated by the vibration of molecules within the object. This method offers higher drying efficiency than conventional hot air drying, and because it operates at lower temperatures, it causes less damage to the object.

[0004] The dielectric heating device may include a power amplifier for providing a high-frequency electric field. At this time, since the dielectric heating device operates at high power (kW class) at a high frequency (e.g., 10 MHz or higher) for drying a material, unlike RF for signaling or communication, the use of a power amplifier capable of high-efficiency operation in a high-frequency band (e.g., a class E power amplifier) ​​is required.

[0005] At this time, the voltage and current limits of the elements included in the circuit may be somewhat low, and if voltage and current stress exceeding the voltage and current limits of the elements are applied to the elements, the function of the elements may deteriorate, resulting in power loss.

[0006] Therefore, parallel operation of the power system is essential, and when power amplifiers are connected in parallel to deliver power to a single load, power imbalance between each channel may occur due to the deviation and parasitic components of the elements included in each power amplifier channel.

[0007] Additionally, if a specific channel is subjected to a large amount of voltage stress due to a power imbalance between channels, the channel may be damaged due to the stress and power concentration, shortening the life of the dryer.

[0008] The disclosed invention relates to a dryer and a control method thereof, including a feedback circuit for controllably resolving the imbalance through the feedback circuit even when a power imbalance occurs between each power amplifier channel.

[0009] According to one embodiment, a dryer may include an RF power supply including a plurality of transistors connected in parallel with each other and generating an RF signal applied to a plurality of electrodes; an error amplifier that amplifies an error voltage between output terminal voltages of the plurality of transistors and a reference voltage, and a feedback circuit including an oscillator that outputs an input signal of a frequency corrected based on the error voltage; and a plurality of gate drivers that amplify an input signal of the frequency corrected output from the feedback circuit and apply the amplified signal to the plurality of transistors.

[0010] In one embodiment, a method for controlling a dryer includes an RF power supply including a first transistor, a second transistor, and a third transistor connected in parallel with each other, a plurality of gate drivers including a first gate driver for applying an input signal to the first transistor, a second gate driver for applying an input signal to the second transistor, and a third gate driver for applying an input signal to the third transistor, a plurality of peak detectors including a first peak detector for detecting a peak voltage of an output terminal voltage of the first transistor, a second peak detector for detecting a peak voltage of an output terminal voltage of the second transistor, and a third peak detector for detecting a peak voltage of an output terminal voltage of the third transistor, an error amplifier, an oscillator, a first switch for connecting the plurality of peak detectors and the error amplifier, and a second switch for connecting the oscillator and the plurality of gate drivers, wherein the method for controlling the dryer may include controlling a connection of the first switch and the second switch based on a preset reference time.

[0011] One aspect of the present disclosure is that power imbalance between power amplifier channels can be controlled without precision passive components.

[0012] Accordingly, the same voltage stress is applied to all power amplifier channels, and the life of the dryer can be extended through even power supply.

[0013] One aspect of the present disclosure is that the circuit can be simplified and the cost reduced by using common components regardless of the number of power amplifier channels.

[0014] The technical problems to be achieved in this document are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0015] Fig. 1 is a drawing showing one embodiment of the external appearance of a dryer (1).

[0016] Figure 2 is a cross-sectional side view of one embodiment of a dryer (1).

[0017] FIG. 3 is a drawing for explaining the operation of a genetic heating device (100) according to one embodiment.

[0018] Figure 4 is a control block diagram of a dryer (1) according to one embodiment.

[0019] FIG. 5 is a diagram illustrating an equivalent circuit of a power amplifier channel (331) constituting an RF power supply unit (102) according to one embodiment.

[0020] FIG. 6 is a diagram illustrating an equivalent circuit of an RF power supply unit (102) implemented as a power amplifier system in which a plurality of power amplifier channels (331) are connected in parallel according to one embodiment.

[0021] Fig. 7 is a block diagram for explaining the operation of a feedback circuit (105) according to one embodiment.

[0022] Fig. 8 is a diagram illustrating an equivalent circuit of an RF power supply (102) and a feedback circuit (105) according to one embodiment.

[0023] Fig. 9 is a diagram illustrating an equivalent circuit of an RF power supply unit (102) and a feedback circuit (105) according to another embodiment.

[0024] Fig. 10 is a diagram showing changes in the output voltage (Vds) of the drain terminal of a transistor (51) according to power imbalance between power amplifier channels (331).

[0025] Fig. 11 is a diagram showing the change in the output voltage (Vds) of the drain terminal of a transistor (51) according to the frequency compensation of the input signal.

[0026] Fig. 12 is a control flowchart of a dryer (1) according to one embodiment.

[0027] Fig. 13 is a control flowchart for operating a feedback circuit (105) in time division according to one embodiment.

[0028] FIG. 14 and FIG. 15 are perspective views showing a dryer having a different shape from the dryer (1) shown in FIG. 1 according to one embodiment.

[0029] FIG. 16 is a perspective view illustrating an oven (3) including a genetic heating device (100) according to one embodiment.

[0030] FIG. 17 is a drawing showing an oven (3) including a genetic heating device (100) according to one embodiment with the door open.

[0031] It should be understood that the technical features are not intended to be limited to specific embodiments, but rather to encompass various modifications, equivalents, or alternatives of the embodiments.

[0032] In connection with the description of the drawings, similar reference numerals may be used for similar or related components.

[0033] 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.

[0034] 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.

[0035] The term "and / or" includes any combination of a plurality of related described elements or any one of a plurality of related described elements.

[0036] 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).

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] Below, a dryer according to various embodiments is specifically described with reference to the attached drawings.

[0042] Fig. 1 is a drawing showing an embodiment of the external appearance of a dryer (1), and Fig. 2 is a side cross-sectional view of an embodiment of the dryer (1).

[0043] Referring to FIGS. 1 and 2, a dryer (1) according to one embodiment includes a main body (10) forming an exterior and a drum (20) rotatably installed within the main body (10) and containing a material to be dried (9).

[0044] The main body (10) may include a base plate (11), a front cover (12), a top cover (13), and a side / rear cover (14).

[0045] An opening (12a) is provided in the front cover (12), and the opening (12a) is opened and closed by a door (15) that is rotatably installed in the front cover (12). A cylindrical drum (20) with an open front can also be opened and closed by the door (15).

[0046] An input unit (30a, 30b) for receiving a user's control command and a display (35) for displaying various information about the operation of the dryer (1) or guiding the user's input can be placed on the top of the front cover (12).

[0047] The input unit (30a, 30b) may be provided in the form of a jog shuttle or dial so that the user can input a control command by holding and turning or pressing the input unit (30a), or may be provided in the form of a touch pad or button so that the user can input a control command by touching or pressing the input unit (30b).

[0048] The display (35) can be implemented by various display panels such as LCD, LED, OLED, and QLED, and can also be implemented as a touch screen by providing a touch pad on the front.

[0049] A front panel (21) having an inlet (21a) formed therein may be arranged on the front of the drum (20), and the drying material (9) may be fed into the drum (20) through the inlet (21a). In addition, the rear of the drum (20) may be closed by a rear panel (22) having an outlet (22a) through which high-temperature dry air is discharged.

[0050] An outlet (21b) through which air used for drying the object to be dried (9) flows out may be provided on the front panel (21) of the drum (20), and a filter (23) for capturing foreign substances generated from the object to be dried (9) may be installed on the outlet (21b).

[0051] That is, the air discharged to the drum (20) through the discharge port (22a) is used for drying the object to be dried (9) and can then be introduced from the drum (20) into the duct (50) through the outlet port (21b). The air used for drying the object to be dried (9) is converted into high-temperature dry air through the heat pump (150) after being introduced into the duct (50) and can then be discharged back to the drum (20) through the discharge port (22a).

[0052] Additionally, at least one lifter having a protruding shape may be formed on the inner wall of the drum (20) to assist in tumbling the drying material (9).

[0053] The drum (20) can rotate by driving force provided from the drum motor (25). The drum (20) is connected to the drum motor (25) by a belt (26), and the belt (26) can transmit the driving force provided from the drum motor (25) to the drum (20).

[0054] The dryer (1) may include a fan (40) that circulates air inside the drum (20). The fan (40) may suck in air from inside the drum (20) and discharge the air through a duct (50). By means of the fan (40), the air inside the drum (20) may circulate through the drum (20) and the duct (50).

[0055] A heat pump (150) may be provided on a duct (50) through which air circulates inside the drum (20). The heat pump (150) may include a compressor (not shown), a condenser (152), an evaporator (154), and an expander (not shown).

[0056] A compressor compresses gaseous refrigerant into a high-temperature, high-pressure state and discharges the compressed high-temperature, high-pressure gaseous refrigerant. For example, the compressor can compress the refrigerant through the reciprocating motion of a piston or the rotary motion of a rotor. The discharged refrigerant is delivered to a condenser (152).

[0057] The condenser (152) can release heat to the surroundings while condensing the compressed gaseous refrigerant into a liquid. The condenser (152) can be installed on the duct (50) and can heat air through the heat generated during the condensation process of the refrigerant. The heated air can be supplied to the drum (20). The liquid refrigerant condensed in the condenser (152) can be transferred to an expander (not shown).

[0058] The expander can expand the high-temperature, high-pressure liquid refrigerant condensed in the condenser (152) into a low-pressure liquid refrigerant. Specifically, the expander can include a capillary tube and an electronic expansion valve whose opening amount can be varied by an electric signal to control the pressure of the liquid refrigerant.

[0059] The evaporator (154) can evaporate the liquid refrigerant expanded in the expander. As a result, the evaporator can return the low-temperature, low-pressure gaseous refrigerant to the compressor.

[0060] The evaporator (154) can absorb heat from the surroundings through an evaporation process that changes low-pressure liquid refrigerant into gaseous refrigerant. The evaporator (154) can be installed on the duct (50) and can cool the air passing through the evaporator (154) during the evaporation process. The surrounding air is cooled by the evaporator (154), and when the temperature of the surrounding air becomes lower than the dew point, the air around the evaporator (154) can condense. The water condensed in the evaporator (154) can be collected by a water collecting tank provided at the bottom of the evaporator (154). The water collected in the water collecting tank can be moved to a separate storage or drained to the outside of the dryer (1).

[0061] As condensation occurs around the evaporator (154), the absolute humidity of the air passing through the evaporator (154) may decrease. In other words, the amount of water vapor contained in the air passing through the evaporator (154) may decrease. By utilizing this condensation around the evaporator (154), the dryer (1) can reduce the amount of water vapor contained in the air inside the drum (20) and dry the object to be dried (9).

[0062] The evaporator (154) may be located upstream of the condenser (152) based on the air flow by the fan (40). The air circulated by the fan (40) may be dried (water vapor may be condensed) by the evaporator (154) while passing through the evaporator (154), and may be heated by the condenser (152) while passing through the condenser (152).

[0063] Meanwhile, a heater (160) may be provided in the duct (50) to heat the air by assisting the condenser (152). The heater (160) may be located downstream from the condenser (152) based on the air flow by the fan (40).

[0064] For example, by additionally heating the air heated in the condenser (152) of the heat pump (150) by the heater (160), the air in the duct (50) can be sufficiently heated.

[0065] The temperature inside the drum (20) can rise more quickly by the heater (160) assisting the condenser (152), and the time required for drying the object to be dried (9) can be shortened.

[0066] A dryer (1) according to one embodiment may include a plurality of electrodes (104) protruding from the inner surface of a drum (20). A pair of electrodes (104) may include a first electrode (401) and a second electrode (402).

[0067] The first electrode (104a) may be placed on the upper side of the drum (20), and the second electrode (104b) may be placed on the lower side of the drum (20). The first electrode (104a) and the second electrode (104b) may be spaced apart from each other with the drum (20) interposed therebetween to form an electric field inside the drum (20). The electric field formed inside the drum (20) may include a high-frequency electric field.

[0068] The first electrode (401) and the second electrode (402) can be implemented using a predetermined conductive plate, and the predetermined conductive plate may include, for example, a predetermined metal plate. In this case, the metal plate may be made of zinc, aluminum, magnesium, or an alloy thereof. In addition, the predetermined conductive plate may be implemented using a ceramic material through which current can flow.

[0069] A dryer (1) according to one embodiment may include a dielectric heating device (100), which will be described below with reference to FIG. 3.

[0070] FIG. 3 is a drawing for explaining the operation of a genetic heating device (100) according to one embodiment.

[0071] A dielectric heating device (100) according to one embodiment may include an RF power source (102) and a plurality of electrodes (104a, 104b). A high-frequency electric field (230) may be formed between the first electrode (104a) and the second electrode (104b) based on power provided from the RF power source (102).

[0072] When an object (e.g., a drying object) located between the first electrode (104a) and the second electrode (104b) contains polar molecules (240) (e.g., water molecules), the object can undergo rotational and / or vibrational motion by the high-frequency electric field (230). The object can be heated by the motion of the polar molecules (240) within the object.

[0073] Polar molecules (240) within an object can be located on the surface and inside of the object, and the part of the object that is heated can be determined depending on the location where the polar molecules (240) are located within the object.

[0074] According to a dielectric heating device (100) according to one embodiment, an object can be uniformly heated due to the movement of polar molecules (240) within the object.

[0075] Figure 4 is a control block diagram of a dryer (1) according to one embodiment.

[0076] Referring to FIG. 4, the dryer (1) may include a dielectric heating device (100). The dielectric heating device (100) may include a DC power supply (101) that generates DC power, an RF power supply (102) that generates an RF signal applied to a plurality of electrodes (104), a matching circuit (103) for matching the impedance of the RF power supply (102) and the impedance between the plurality of electrodes (104), and a feedback circuit (105) that corrects the frequency of a control signal input to the plurality of electrodes (104) that form an electric field within the drum (20) and / or the RF power supply (102).

[0077] In addition, the dryer (1) may include a user interface (400) for obtaining user input or displaying various information related to the operation of the dryer (1), a communication interface (500) for establishing communication with an external device, and / or a control unit (300) for controlling each component of the dryer (e.g., a DC power supply (101), an RF power supply (102), a matching circuit (103), a plurality of electrodes (104), a feedback circuit (105), the user interface (400), and / or the communication interface (500).

[0078] According to various embodiments, the configuration of the dryer (1) is not limited to that described in FIG. 4. Other configurations may be added in addition to those described in FIG. 4, or the configurations described in FIG. 4 may be omitted. For example, the dryer (1) may further include a humidity sensor for detecting humidity within the drum (20) and a weight sensor for detecting the weight of the object to be dried.

[0079] The DC power supply unit (101) can convert AC power supplied from a commercial power source (C) into DC power and supply it to the RF power supply unit (102). The DC power supply unit (101) can be electrically connected to the RF power supply unit (102) to supply DC power to the RF power supply unit (102).

[0080] The DC power supply unit (101) may include an EMI (Electro Magnetic Interference) filter for removing noise included in AC power, a power factor correction circuit (PFC) for compensating for the power factor of the AC power, and / or a DC converter for converting power output from the power factor correction circuit into DC power in order to convert AC power supplied from a commercial power source (C) into DC power.

[0081] The control unit (300) can control the DC power supply unit (101) to adjust the magnitude of the voltage applied to the plurality of electrodes (104). When the DC power supplied to the RF power supply unit (102) increases, the amplitude of the RF signal increases, and the magnitude of the voltage applied to the plurality of electrodes (104) can increase. The magnitude of the voltage can be expressed as an effective value. At this time, the amplitude of the RF signal can correspond to the drain terminal voltage waveform of the transistor (51) included in the RF power supply unit (102).

[0082] The RF power supply (102) can generate an RF signal and apply the RF signal to the electrode (104). The RF power supply (102) can be implemented as a power amplifier system in which multiple power amplifier channels are connected in parallel. Each configuration and function of the RF power supply (102) will be described in detail below with reference to FIGS. 5 and 6.

[0083] A matching circuit (103) may be provided between an RF power source (102) and a plurality of electrodes (104). An RF signal generated by the RF power source (102) may be transmitted to the plurality of electrodes (104) through the matching circuit (103). A sinusoidal voltage may be applied to the plurality of electrodes (104) by the RF signal. The control unit (300) may control the RF power source (102) to generate an RF signal.

[0084] The matching circuit (103) can match the impedance between the RF power source (102) and the plurality of electrodes (104). For example, the matching circuit (103) can match the impedance of the RF power source (102) and the impedance of the plurality of electrodes (104). The impedance of the RF power source (102) can include the impedance of the output terminal of the RF power source (102). The impedance of the plurality of electrodes (104) can include the impedance of the input terminal of the plurality of electrodes (104).

[0085] If there is a difference between the impedance of the RF power supply (102) and the impedance of the plurality of electrodes (104), reflected power is generated from the electrodes (104), and power transmission efficiency is reduced. In order to minimize the reflected power, matching of the impedance of the RF power supply (102) and the impedance of the plurality of electrodes (104) is required.

[0086] A plurality of electrodes (104) can form an electric field inside the drum (20) based on an applied sinusoidal voltage. The electric field formed inside the drum (20) can include a high-frequency electric field. The plurality of electrodes (104) can be spaced apart and arranged inside the drum (20).

[0087] According to various embodiments, the DC power supply (101), the RF power supply (102), and the matching circuit (103) may be provided as a single power module. In other words, the DC power supply (101) and the matching circuit (103) may be included in the RF power supply (102). One power module may be common to a plurality of electrodes (104), and the plurality of electrodes (104) may be connected in parallel to one power module.

[0088] Additionally, a plurality of DC power sources (101), a plurality of RF power sources (102), and a plurality of matching circuits (103) may be provided corresponding to each of the plurality of electrodes (104). That is, a plurality of power modules including the DC power source (101), the RF power source (102), and the matching circuit (103) may be provided. Each of the plurality of electrodes (104) may be independently connected to each power module.

[0089] The feedback circuit (105) is connected to the RF power supply (102) and can correct the frequency of the input signal input to the RF power supply (102). At this time, the input signal may correspond to a pulse-shaped signal (e.g., a square wave) input through a gate to drive the RF power supply (102) and generate an RF signal.

[0090] The feedback circuit (105) can be connected to the RF power supply (102) to form a closed loop.

[0091] The control unit (300) can control the feedback circuit (105) to correct the frequency of the input signal applied to the RF power supply unit (102).

[0092] The control unit (300) may include a processor (310) and a memory (320). The memory (320) may include volatile memory (e.g., S-RAM, D-RAM) and non-volatile memory (e.g., ROM, EPROM). The processor (310) and the memory (320) 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. The processor (310) may process various data and various signals using instructions, data, programs, and / or software stored in the memory (320). The processor (310) may generate control signals for controlling components of the dryer (1). The processor (310) may include one core or a plurality of cores.

[0093] The control unit (300) can be electrically connected to components of the dryer (1) and can control the components of the dryer (1). For example, the control unit (300) can control the motor (72) to rotate the drum (20) and the fan (71). In addition, the control unit (300) can control the DC power supply (101), the RF power supply (102) and / or the matching circuit (103) to apply a sinusoidal voltage to a plurality of electrodes (104). In addition, the feedback circuit (105) can be controlled to correct the frequency of the input signal applied to the RF power supply (102).

[0094] The control unit (300) can control the connection of the first switch (1055) and the second switch (1056). Specifically, the control unit (300) can control the connection of the first switch (1055) and the second switch (1056) based on a preset reference time, which will be described in detail later.

[0095] The user interface (400) can acquire user input and display various information regarding the operation of the dryer (1). The user interface (400) can include an input unit for acquiring user input and a display for displaying information. In addition, the user interface (400) can also include a speaker for outputting sound.

[0096] The user interface (400) may display operating information of the dryer (1). For example, the user interface (400) may display a drying course, a drying temperature, an estimated drying time, and / or a remaining time until the end of drying. The drying course may include predetermined drying settings (e.g., drying level, additional time to prevent wrinkles, drying time) depending on the type of object to be dried (e.g., shirt, blanket, underwear) and material (e.g., cotton, wool). For example, the standard drying may include drying settings applicable to most objects, and the blanket drying may include drying settings optimized for drying blankets.

[0097] The input interface (410) may include, for example, 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.

[0098] The output interface (420) can transmit various information related to the operation of the dryer (1) to the user.

[0099] Information related to the operation of the dryer (1) can be output through a screen, indicator, voice, etc. The output interface (420) can include, for example, a liquid crystal display (LCD) panel, a light emitting diode (LED) panel, a speaker, etc.

[0100] The communication interface (500) can connect to at least one of a user device (e.g., a user terminal) or a server via a network. The control unit (300) can obtain various information, various signals, and / or various data from the user device or the server via the communication interface (500). For example, the communication interface (500) can receive a remote control signal from the user device. The control unit (300) can obtain firmware and / or software for the operation of the dryer (1) from the server via the communication interface (500).

[0101] The communication interface (500) may include various communication circuits. The communication interface (500) 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.

[0102] The RF power supply (102) may include various configurations to ensure high power transmission amplification from the DC power supply (101) (i.e., the ability to amplify the input signal received by the RF power supply (102) and stably transmit high power to a plurality of electrodes (104). The configuration of the RF power supply (102) will be described below with reference to FIG. 5.

[0103] FIG. 5 is a diagram illustrating an equivalent circuit of a power amplifier channel (331) constituting an RF power supply unit (102) according to one embodiment.

[0104] Referring to FIG. 5, an RF power supply (102) according to one embodiment may be implemented as a power amplifier system including at least one power amplifier channel (331) or as a part thereof. The RF power supply (102) implemented as a power amplifier system may be a power module including a matching circuit (103).

[0105] A power amplifier channel (331) according to one embodiment may include an E CLASS power amplifier. The power amplifier channel (331) may output power to a plurality of electrodes (104) using power provided from a DC power supply (101).

[0106] An RF power supply (102) according to one embodiment may include a transistor (51), an inductor (e.g., an RF (radio frequency) choke inductor (Lchk) (52)), a capacitor (e.g., a shunt capacitor (Csh) (53)), and / or a resonant circuit (54). The RF power supply (102) may configure a resonant switching cell and operate as an AC voltage source according to a switching operation.

[0107] The transistor (51) can operate by receiving a driving voltage (VDD) from the DC power supply (101). At this time, the transistor (51) can be turned on or off by receiving an input signal (6) in the form of a pulse (e.g., a square wave) through an input terminal (e.g., a gate). As described above, the input signal (6) can be a signal applied from the outside (e.g., the input signal generation unit (601) of FIG. 7) to drive the RF power supply (102) to generate an RF signal.

[0108] For example, the transistor (51) may include a bipolar junction transistor (BJT) or a metal oxide semiconductor field effect transistor (MOSFET). If the transistor (51) is an N-channel MOSFET (NMOS), the input signal (6) may be a gate voltage applied to the gate terminal of the N-channel MOSFET. The source of the transistor (51) may be connected to ground, and the drain may be connected to an output node (7).

[0109] The inductor included in the RF power supply (102) can be implemented as a choke inductor (52). The choke inductor (52) can block the RF signal from being transmitted from the DC power supply (101) to the transistor (51) so that only DC current is transmitted to the transistor (51).

[0110] The capacitor included in the RF power supply (102) may include a shunt capacitor (53). The shunt capacitor (53) is connected in parallel with the transistor (51) and may be discharged or charged while the transistor (51) is turned on or off. At this time, the shunt capacitor (53) may be a separate capacitor connected in parallel with the transistor (51) and may be described as a concept including the internal capacitance of the transistor (51) (e.g., drain-source capacitance (Cds)).

[0111] Based on the transistor (51) being turned on or off according to the input signal (6), RF power can be generated, and the generated RF power can be transmitted to the series LC resonant circuit (54) through the output node (7).

[0112] More specifically, when the transistor (51) is turned on, the transistor (51) is electrically short-circuited and can be interpreted as a short circuit to the ground connected to the source, and the voltage at the output node (7) can be interpreted as 0. The current flowing to the transistor (51) through the choke inductor (52) can gradually increase.

[0113] At this time, the voltage of the output node (7) may be a concept corresponding to the voltage across the shunt capacitor (53) or the output terminal voltage (Vds) of the transistor (51). Hereinafter, it will be described unified as the output terminal voltage (Vds) of the transistor (51).

[0114] Thereafter, when the transistor (51) is turned off, the current flowing through the choke inductor (52) is directed to the shunt capacitor (53), and as the shunt capacitor (53) is gradually charged, the output voltage (Vds) of the transistor (51) may increase until it reaches a peak value. Thereafter, as the shunt capacitor (53) is gradually discharged, the current flows from the shunt capacitor (53) to the series LC resonant circuit (54) through the output node (7), and the output voltage (Vds) of the transistor (51) may gradually decrease. In the power amplifier channel (331), for high-efficiency operation (e.g., to minimize power consumed in the transistor (51)), the transistor (51), the shunt capacitor (53) and the input signal (6) may be set so that the output voltage (Vds) of the transistor (51) gradually decreases to 0 before the transistor (51) is turned on again after being turned off (e.g., before current starts to flow to the transistor (51) again through the choke inductor (52)), and the amount of change in the decrease in the output voltage (Vds) of the transistor (51) becomes 0.

[0115] The LC resonant circuit (54) may include at least one resonant inductor (Lr) and at least one resonant capacitor (Cr) connected in series with each other. The LC resonant circuit (54) may be set to have a resonant frequency corresponding to the operating frequency so as to resonate with the operating frequency of the input signal (6). For example, the resonant inductor (Lr) and the resonant capacitor (Cr) having inductance values ​​and capacitance values ​​such that the reactance value of the equivalent impedance of the LC resonant circuit (54) becomes 0 at the operating frequency of the input signal (6) may be designed to be included in the series LC resonant circuit (54). At this time, the amount of change in the output voltage (Vds) of the transistor (51) over time may vary depending on the element value of the resonant circuit (54), i.e., the inductance of the resonant inductor (Lr) or the capacitance value of the resonant capacitor (Cr). That is, as the transistor (51) is turned off and the shunt capacitor (53) is charged and discharged, current flows to the resonant circuit (54), and the peak value of the output voltage (Vds) of the transistor (51) may be determined by the element value of the resonant circuit (54).

[0116] In the RF power supply (102), based on whether the transistor (51) is turned on or off in response to the input signal (6), current flows from the choke inductor (52) to the transistor (51) or the shunt capacitor (53), or from the shunt capacitor (53) to the LC resonant circuit (54), thereby generating an alternating current (AC). Accordingly, the alternating current generated through the LC resonant circuit (54) can be output to the matching circuit (103) and / or the plurality of electrodes (104), thereby generating an alternating voltage (e.g., a sinusoidal voltage) at the plurality of electrodes (104).

[0117] The generation of an alternating current based on the above-described transistor (51) being turned on or off can be explained as the generation of an RF signal based on the transistor (51) being turned on or off.

[0118] FIG. 6 is a diagram illustrating an equivalent circuit of an RF power supply unit (102) implemented as a power amplifier system in which a plurality of power amplifier channels (331) are connected in parallel according to one embodiment.

[0119] According to one embodiment, a plurality of power amplifier channels (331) (e.g., a first channel (Ch1), a second channel (Ch2), and a third channel (Ch3)) may be connected in parallel to form a power amplifier system. In the present disclosure, a power amplifier system in which three power amplifier channels (331) are connected in parallel is described as an example with reference to FIG. 6, but the number of amplifier channels (331) that may be connected in parallel is not limited.

[0120] At this time, the power amplifier system may include a separate matching circuit (103) for each power amplifier channel (331) or may include one common matching circuit (103).

[0121] An RF power supply (102) according to one embodiment may be implemented as a power amplifier system or part thereof in which a plurality of power amplifier channels (331) are connected in parallel.

[0122] In other words, the RF power supply unit (102) may include a part of a first power amplifier channel (Ch1) including a first choke inductor (52a), a first transistor (51a) receiving a first input signal (Vg1), a first shunt capacitor (53a) and / or a first resonant circuit (54a), a part of a second power amplifier channel (Ch2) including a second choke inductor (52b), a second transistor (51b) receiving a second input signal (Vg2), a second shunt capacitor (53b) and / or a second resonant circuit (54b), and a part of a third power amplifier channel including a third choke inductor (52c), a third transistor (51c) receiving a third input signal (Vg3), a third shunt capacitor (53c) and / or a third resonant circuit (54c).

[0123] Alternatively, when the RF power supply (102) is implemented as a power module including a matching circuit (103), the RF power supply (102) may further include a matching circuit (103).

[0124] At this time, there is a component deviation in the components (e.g., transistors, inductors, and / or capacitors) that actually constitute each power amplifier channel (331). To minimize the component deviation, precision components (e.g., precision inductors and / or precision capacitors) can be manufactured, but the difficulty thereof is high and the manufacturing cost may increase. In addition to the component deviation, the component value (e.g., inductance of an inductor or capacitance of a capacitor) may become larger or smaller due to differences in layout between each power amplifier channel (331).

[0125] Although the error is not large in low-frequency circuits, the circuit error may increase in high-frequency circuits (e.g., 13.56 MHz or higher), such as the RF power supply (102) of a dryer (1) including a dielectric heating device (100). Accordingly, an imbalance in the power applied to each power amplifier channel (331) (i.e., voltage stress imbalance) may occur.

[0126] To solve the above-described problem, the dryer (1) according to one embodiment may further include a feedback circuit (105). The control unit (300) of the dryer (1) according to one embodiment may resolve the imbalance by controlling the frequency of the input signal (6) through the feedback circuit (105), even when an imbalance occurs. This will be described below with reference to FIG. 7.

[0127] Fig. 7 is a block diagram for explaining the operation of a feedback circuit (105) according to one embodiment.

[0128] A dryer (1) according to one embodiment may include an input signal generation unit (601), a multiplexer (602) and / or at least one gate driver (603) to generate an input signal (6).

[0129] In order for the RF power supply (102) according to one embodiment to generate an RF signal, an input signal (6) for driving the transistor (51) must be applied. The RF power supply (102) can generate an RF signal by amplifying the input signal (6) by driving the transistor (51).

[0130] At this time, when the RF power supply unit (102) is implemented as a power amplifier system or part thereof in which a plurality of power amplifier channels (331) are connected in parallel, the same input signal (6) is applied to the transistors included in each power amplifier channel (331) (e.g., the first transistor (51a) or the second transistor (51b), the third transistor (51c) of FIG. 7), and the RF signals generated in each channel are combined at the contact point where each power amplifier channel (331) is connected in parallel to provide an RF signal combined by the matching circuit (103) and / or the plurality of electrodes (104).

[0131] The input signal generation unit (601) can generate an input signal (6) for generating an RF signal. The input signal generation unit (601) can be implemented as an MCU, a digital logic circuit, or an FPGA. The control unit (300) can control the input signal generation unit (601) to generate the input signal (6). For example, the multiplexer (602) can be implemented as a 1 to N multiplexer. In this case, the number of output terminals of the multiplexer (602) can correspond to the number of power amplifier channels (331).

[0132] The multiplexer (602) can branch the input signal (6) generated from the input signal generation unit (601) to transmit the input signal (6) to the transistor (51) included in each power amplifier channel (331).

[0133] When the input signal (6) generated in the input signal generation unit (601) is directly applied to each power amplifier channel (331), the transistor (51) may not operate due to limitations in maximum current driving capability. Accordingly, the input signal (6) is branched through the multiplexer (602) and provided to each power amplifier channel (331) to stably drive the transistor (51).

[0134] The gate driver (603) can increase the voltage of the input signal (6) to drive the transistor (51). The voltage of the input signal (6) branched from the multiplexer (602) can be lower than the threshold voltage for driving the transistor (51). Accordingly, the gate driver (603) can increase the voltage of the input signal (6) to a voltage suitable for operating the transistor (51).

[0135] A dryer (1) according to one embodiment may include a plurality of gate drivers (603a, 603b, 603c). The plurality of gate drivers (603a, 603b, 603c) may have one end connected to each of the output terminals of the multiplexer (602), and the other end connected to each of the plurality of transistors (51a, 51b, 51c).

[0136] The input signal (6) output from each of the plurality of gate drivers (603a, 603b, 603c) can be transmitted to the transistor connected to the other end of the plurality of transistors (51a, 51b, 51c) in the form of a gate voltage (e.g., Vg1, Vg2, Vg3 of FIG. 7). At this time, the gate driver (603) only increases the voltage of the input signal (6) without changing the frequency, so the frequency of the input signal (6) transmitted to each of the plurality of transistors (51a, 51b, 51c) can be the same.

[0137] A dryer (1) according to one embodiment may further include a feedback circuit (105) to correct the frequency of an input signal (6) transmitted to each of a plurality of transistors (51a, 51b, 51c). The feedback circuit (105) according to one embodiment may include a voltage sensor (1051), a peak detector (1502), an error amplifier (1053), and / or a voltage controlled oscillator (VCO) (1054).

[0138] The feedback circuit (105) can be implemented as a closed loop circuit in which one end is connected to the drain end of the transistor (51) and the other end is connected to the gate driver (603).

[0139] The voltage sensor (1051) is connected to each power amplifier channel (331) and can detect the drain terminal output voltage of the transistor (51) (i.e., the output terminal voltage (Vds) of the transistor (51)). The voltage sensor (1051) may further include a voltage divider for lowering the output terminal voltage (Vds) of the transistor (51) to the level of the input signal (6).

[0140] The peak detector (1502) can detect the peak value of the output voltage (Vds) of the transistor (51). The output voltage (Vds) of the transistor (51) can be formed into a sine wave by the resonant circuit (54). Accordingly, the feedback circuit (105) can include the peak detector (1502) to measure the highest voltage value. The peak detector (1502) can change the peak value of the output voltage (Vds) of the transistor (51) into a DC voltage and transmit information about the DC voltage value to the error amplifier (1053).

[0141] The error amplifier (1053) can amplify and output the difference between the peak value of the output voltage (Vds) of the transistor (51) converted into a DC voltage and the reference voltage. The reference voltage may be a preset value. The error amplifier (1053) can transmit the voltage error value as an input value of the voltage controlled oscillator (1054).

[0142] The oscillator (1054) can correct the frequency of the input signal (6) based on the error between the reference voltage and the peak value of the output voltage (Vds) of the transistor (51). That is, the oscillator (1054) can generate a changed frequency input signal using the voltage as an input value.

[0143] The oscillator (1054) can perform frequency correction of the input signal (6) based on the peak value of the output terminal voltage (Vds) of the transistor (51) to resolve power imbalance caused by component deviation and differences in PCB layout.

[0144] The control unit (300) can control the feedback circuit (105) to resolve voltage stress caused by power imbalance in each power amplifier channel (331) of the RF power supply unit (102) through frequency correction of the input signal of each power amplifier channel (331). This will be described below with reference to FIGS. 8 and 9.

[0145] Fig. 8 is a diagram illustrating an equivalent circuit of an RF power supply (102) and a feedback circuit (105) according to one embodiment.

[0146] The structure and each configuration of the RF power supply unit (102) of FIG. 7 may correspond to the RF power supply unit (102) described above in FIG. 5.

[0147] A feedback circuit (105) according to one embodiment may include a plurality of voltage sensors (1051a, 1051b, 1051c) connected to the output terminals (i.e., output nodes (7)) of the transistors (51) of each of the plurality of power amplifier channels (331).

[0148] Each of the plurality of voltage sensors (1051a, 1051b, 1051c) may further include a voltage divider. The voltage divider may include a plurality of resistors. The plurality of resistors may be connected in series. One end of the voltage divider may be connected to the output node (7) of the transistor (51), and the other end may be connected to ground. Accordingly, the voltage divider may receive the output terminal voltage (Vds) of the transistor (51) from the input terminal, and divide the output terminal voltage (Vds) of the transistor (51) to the level of the input signal (6) based on the resistance values ​​of the plurality of resistors.

[0149] A feedback circuit (105) according to one embodiment may include a plurality of peak detectors (1052a, 1052b, 1052c) connected to a plurality of voltage sensors (1051a, 1051b, 1051c). Each of the plurality of peak detectors (1052a, 1052b, 1052c) may receive an output terminal voltage (Vds) of a transistor (51) divided by a voltage sensor (1051a, 1051b, or 1051c) to which one end is connected.

[0150] The plurality of peak detectors (1052a, 1052b, 1052c) may include at least capacitors and resistors connected in parallel with each other. The plurality of peak detectors (1052a, 1052b, 1052c) can detect the peak value of the input signal (6), i.e., the output terminal voltage (Vds) of the transistor (51), by the principle that when the input signal (6) rises, the output signal also rises, and when the input signal (6) falls, the output signal slowly falls by the parallel RC circuit.

[0151] In other words, the plurality of peak detectors (1052a, 1052b, 1052c) can detect the peak value of the output terminal voltage (Vds) of the transistor (51) of the power amplifier channel (331) to which each of the plurality of peak detectors (1052a, 1052b, 1052c) is connected. At this time, the peak value of the output terminal voltage (Vds) can be detected in the form of a DC voltage.

[0152] A feedback circuit (105) according to one embodiment may include a plurality of error amplifiers (1053a, 1053b, 1053c) connected to a plurality of peak detectors (1052a, 1052b, 1052c). Each of the plurality of error amplifiers (1053a, 1053b, 1053c) may receive a peak value of an output terminal voltage (Vds) of a transistor (51) from a peak detector (1052a, 1052b, or 1052c) to which one end is connected.

[0153] The (-) terminal of multiple error amplifiers (1053a, 1053b, 1053c) is provided with a reference voltage (V) of DC value. ref ) is applied, and the peak value of the output voltage (Vds) of the transistor (51) can be input to the (+) terminal. At this time, the reference voltage (V ref ) can be a preset value.

[0154] Accordingly, each of the plurality of error amplifiers (1053a, 1053b, 1053c) can amplify and output the error between the peak value of the output terminal voltage (Vds) of the input transistor (51) and the reference voltage.

[0155] A feedback circuit (105) according to one embodiment may include a plurality of oscillators (1054a, 1054b, 1054c) connected to a plurality of error amplifiers (1053a, 1053b, 1053c). Each of the plurality of oscillators (1054a, 1054b, 1054c) may correct the frequency of an input signal (6) input to each power amplifier channel (331) based on an error between a peak value of an output terminal voltage (Vds) of a transistor (51) input from an error amplifier (1053a, 1053b or 1053c) to which one end is connected and a reference voltage.

[0156] Specifically, the oscillator (1054a, 1054b or 1054c) can correct the frequency of the input signal in the direction of lowering the output voltage (Vds) of the high transistor (51) when the error between the peak value of the output voltage (Vds) of the transistor (51) and the reference voltage is large.

[0157] A plurality of oscillators (1054a, 1054b, 1054c) can output a frequency-corrected input signal (6) to gate drivers (603a, 603b, 603c) connected to the other ends of each of the plurality of oscillators (1054a, 1054b, 1054c). Accordingly, each of a plurality of power amplifier channels (331) connected in parallel to each other in the RF power supply unit (102) can generate RF power by the frequency-corrected input signal (6).

[0158] For example, the oscillator (1054a, 1054b or 1054c) may be configured to output an input signal (6) of a preset reference frequency (e.g., 13.56 MHz) based on a preset threshold voltage (e.g., 0 V) ​​being input as an error.

[0159] In addition, the oscillator (1054a, 1054b or 1054c) can compensate the frequency of the input signal (6) so that the frequency is lowered below a preset reference frequency based on the error input from the error amplifier (1053a, 1053b or 1053c) being greater than a preset threshold voltage. Accordingly, the frequency of the input signal (6) input to the transistor (51) can be lowered, thereby lowering the peak voltage of the output terminal voltage (Vds) of the transistor (51).

[0160] The feedback circuit (105) according to FIG. 8 may include a voltage sensor (1051), a peak detector (1052), an error amplifier (1053), and an oscillator (1054) corresponding to the number of each power amplifier channel (331). However, in this case, the number of elements included in the feedback circuit (105) increases, which may increase the manufacturing cost and increase the overall volume of the PBC layout.

[0161] Accordingly, each power amplifier channel (331) can use some of the elements constituting the feedback circuit (105) as common elements to improve economy and reduce volume, which will be described below with reference to FIG. 9.

[0162] Fig. 9 is a diagram illustrating an equivalent circuit of an RF power supply unit (102) and a feedback circuit (105) according to another embodiment.

[0163] The structure and each configuration of the RF power supply unit (102) of FIG. 8 may correspond to the RF power supply unit (102) described above in FIG. 5.

[0164] A feedback circuit (105) according to another embodiment may include a plurality of voltage sensors (1051a, 1051b, 1051c) connected to the output terminals (i.e., output nodes (7)) of the transistors (51) of each of the plurality of power amplifier channels (331), and a plurality of peak detectors (1052a, 1052b, 1052c) connected to each of the plurality of voltage sensors (1051a, 1051b, 1051c).

[0165] A plurality of voltage sensors (1051a, 1051b, 1051c) and a plurality of peak detectors (1052a, 1052b, 1052c) included in a feedback circuit (105) according to another embodiment may correspond to the feedback circuit (105) according to one embodiment described with reference to FIG. 8.

[0166] A feedback circuit (105) according to another embodiment may include one error amplifier (1053) and one oscillator (1054). At this time, one end of one error amplifier (1053) may be connected to multiple peak detectors (1052a, 1052b, 1052c) through a first switch (1055), and the other end may be connected to one oscillator (1054). One oscillator (1054) may have one end connected to one error amplifier (1053), and the other end connected to multiple gate drivers (603a, 603b, 603c) through a second switch (1056). That is, in correcting the frequency of the input signal (6) of multiple power amplifier channels (331), one error amplifier (1053) and one oscillator (1054) may be used as common elements.

[0167] Referring to FIG. 9, the first switch (1055) may include three input terminals and two output terminals. The three input terminals may be connected to a first peak detector (1052a), a second peak detector (1052b), and a third peak detector (1052c), respectively, and one output terminal may be connected to one error amplifier (1053).

[0168] The control unit (300) can control the first switch (1055) so that one error amplifier (1053) is connected to one of the first peak detector (1052a), the second peak detector (1052b), or the third peak detector (1052c).

[0169] In the present disclosure, the first switch (1055) is described as having three input terminals, but this is merely an example, and as the number of power amplifier channels (331) connected in parallel with each other increases or decreases, the number of peak detectors (1052) included in the feedback circuit (105) may increase or decrease, and thus the number of input terminals of the first switch (1055) may also increase or decrease correspondingly.

[0170] Referring to FIG. 9, the second switch (1056) may include one input terminal and three output terminals. One input terminal may be connected to one oscillator (1054), and the three output terminals may be connected to one of the first gate driver (603a), the second gate driver (603b), or the third gate driver (603c).

[0171] The control unit (300) can control the second switch (1056) so that one oscillator (1054) is connected to one of the first gate driver (603a), the second gate driver (603b), or the third gate driver (603c).

[0172] In the present disclosure, the second switch (1056) is described as having three output terminals, but this is merely an example, and as the number of power amplifier channels (331) connected in parallel increases or decreases, the number of gate drivers (603) may increase or decrease, and thus the number of output terminals of the second switch (1056) may also increase or decrease correspondingly.

[0173] The control unit (300) can perform frequency correction of the input signal (6) applied to each power amplifier channel (331) using the error amplifier (1053) and the oscillator (1054) in a time-division manner by controlling the first switch (1055) and the second switch (1056). At this time, the control unit (300) can control the first switch (1055) and the second switch (1056) in synchronization.

[0174] Hereinafter, with reference to FIGS. 10 and 11, the change in the output voltage (Vds) of the drain terminal of the transistor (51) due to the resolution of the power imbalance between the power amplifier channels (331) through the feedback circuit (105) will be described.

[0175] Fig. 10 is a diagram showing changes in the output voltage (Vds) of the drain terminal of a transistor (51) according to power imbalance between power amplifier channels (331).

[0176] The x-axis of Fig. 10 represents time (s), and the y-axis represents the drain terminal output voltage of each power amplifier channel (331) (i.e., the output terminal voltage (Vds) of the transistor (51)). Each graph represents the change in the output terminal voltage (Vds) of the transistor (51) over time when an input signal (6) of the same frequency is applied to the first power amplifier channel (Ch1), the second power amplifier channel (Ch2), and the third power amplifier channel (Ch3).

[0177] As described with reference to FIG. 5, when the transistor (51) is turned on, the transistor (51) is electrically short-circuited, so that the output voltage (Vds) of the transistor (51) can be output as 0. On the other hand, when the transistor (51) is turned off, as the shunt capacitor (53) is gradually charged, the output voltage (Vds) of the transistor (51) increases until it reaches a peak value, and as the shunt capacitor (53) is gradually discharged, current flows from the shunt capacitor (53) to the series LC resonant circuit (54) through the output node (7), so that the output voltage (Vds) of the transistor (51) can gradually decrease.

[0178] At this time, since Fig. 10 shows the change in the output voltage (Vds) of the transistor (51) over time when an input signal (6) of the same frequency is input to each power amplifier channel (331), the period from T0 to T1 may correspond to the time when the transistors (51) of all channels are turned off, the period from T1 to T2 may correspond to the time when the transistors (51) of all channels are turned on, and the period from T2 to T3 may correspond to the time when the transistors (51) of all channels are turned off.

[0179] Referring to Fig. 10, the peak voltage of each channel is the peak voltage (V) of the first power amplifier channel (Ch1). DS1 )> Peak voltage (V) of the second power amplifier channel (Ch1) DS2 )> Peak voltage (V) of the third power amplifier channel (Ch3) DS3 ), it can be confirmed that the highest voltage is applied to the first power amplifier channel (Ch1) from the DC power supply (101). At this time, the peak voltage (VDS3) of the third power amplifier channel (Ch3) may be a threshold voltage.

[0180] Fig. 11 is a diagram showing the change in the output voltage (Vds) of the drain terminal of a transistor (51) according to the frequency compensation of the input signal.

[0181] The x-axis of Fig. 11 represents time (s), and the y-axis represents the drain terminal output voltage of each power amplifier channel (331) (i.e., the output terminal voltage (Vds) of the transistor (51)). Each graph represents a change in the output terminal voltage (Vds) of the transistor (51) over time when an input signal (6) having a frequency corrected based on the peak voltage is applied to the first power amplifier channel (Ch1), the second power amplifier channel (Ch2), and the third power amplifier channel (Ch3).

[0182] Peak voltage (V) of the first power amplifier channel (Ch1) DS1 ) is the threshold voltage (V DS3 ) is detected to be higher than the reference frequency, the control unit (300) can reduce the frequency of the input signal of the first power amplifier channel (Ch1) compared to the reference frequency through the feedback circuit (105).

[0183] Additionally, the peak voltage (V) of the second power amplifier channel (Ch2) DS2 ) is the threshold voltage (V DS3 ) is detected to be higher than the reference frequency, the control unit (300) can reduce the frequency of the input signal of the second power amplifier channel (Ch2) compared to the reference frequency through the feedback circuit (105).

[0184] At this time, the frequency reduction amount of the input signal may be such that the frequency of the input signal of the first power amplifier channel (Ch1) is greater than the frequency of the input signal of the second power amplifier channel (Ch2).

[0185] Accordingly, the period during which the transistor (51) of each power amplifier channel (331) is turned off may be a period during which the first power amplifier channel (Ch1) is turned off (a period of T0' to T3' or a period of T4' to T7') > a period during which the second power amplifier channel (Ch2) is turned off (a period of T0' to T2' or a period of T4' to T6') > a period during which the third power amplifier channel (Ch3) is turned off (a period of T0' to T1' or a period of T4' to T5').

[0186] Accordingly, the control unit (300) performs frequency correction based on the output terminal voltage (Vds) of each of the plurality of transistors (51) included in the plurality of power amplifier channels (331), thereby alleviating the imbalance of voltage stress applied to each channel and extending the life of the dryer (1).

[0187] Fig. 12 is a control flowchart of a dryer (1) according to one embodiment.

[0188] The control unit (300) of the dryer (1) according to one embodiment can perform frequency correction of the individual input signal (6) of each transistor (51) based on the output terminal voltage (Vds) of each of the plurality of transistors (51) included in the RF power supply unit (102).

[0189] The control unit (300) can control a plurality of voltage sensors (1051) to detect the output terminal voltage (Vds) of a plurality of transistors (51) (1201).

[0190] The control unit (300) detecting the output terminal voltage (Vds) of the plurality of transistors (51) may include detecting the output terminal voltage (Vds) of the plurality of transistors (51) through a voltage sensor (1501) connected to the output terminal of each transistor (51).

[0191] Thereafter, the control unit (300) can control the voltage divider (1202) to lower the output voltage (Vds) of the detected transistor (51) to the level of the input signal (6). At this time, since the voltage divider can be included in the voltage sensor (1051), controlling the voltage divider can be interpreted as controlling the voltage sensor (1051).

[0192] The control unit (300) can control a plurality of peak detectors (1052) to detect each peak voltage from the output terminal voltage (Vds) of a plurality of transistors (51) lowered to the level of the input signal (6) (1203).

[0193] A plurality of peak detectors (1052) are each connected to a plurality of voltage sensors (1051), and can detect a peak voltage from the output terminal voltage (Vds) of the transistor (51) in the form of a sinusoidal wave received from the voltage sensor (1051) and convert it into a DC voltage value.

[0194] The control unit (300) can control the error amplifier (1053) to compare the peak voltage detected from the plurality of peak detectors (1052) with a preset reference voltage and amplify the error (1204).

[0195] At this time, the error amplifier (1053) may be provided with a plurality of error amplifiers (1053) such that one error amplifier (1053) is connected to each of the plurality of peak detectors (1052) (i.e., corresponding to the number of the plurality of peak detectors (1052).

[0196] In addition, one error amplifier (1053) is provided, and the peak voltage detected by the plurality of peak detectors (1052) may be transmitted to the error amplifier (1053) according to the operation of the first switch (1055) provided between the error amplifier (1053) and the plurality of peak detectors (1052).

[0197] The control unit (300) can control the voltage controlled oscillator (1054) to correct the frequency of the input signal (6) based on the error voltage received from a plurality of error amplifiers (1053) or one error amplifier (1053) (1205).

[0198] The control unit (300) can compare a preset threshold voltage and an error voltage, and if the error voltage is greater than the threshold voltage, perform frequency correction of the input signal (6) to reduce the frequency of the input signal (6) below the reference frequency.

[0199] At this time, the greater the difference between the error voltage and the threshold voltage, the greater the decrease in the frequency of the input signal (6).

[0200] At this time, the voltage controlled oscillator (1054) may be provided with a plurality of voltage controlled oscillators (1054) so ​​that one voltage controlled oscillator (1054) is connected to each of the plurality of error amplifiers (1053) corresponding to the number of error amplifiers (1053).

[0201] Additionally, one voltage controlled oscillator (1054) may be provided corresponding to one error amplifier (1053).

[0202] The control unit (300) can apply a frequency correction input signal (6) output from the voltage controlled oscillator (1206) to a plurality of gate voltages connected to the voltage controlled oscillator (1206) (1206).

[0203] When multiple voltage-controlled oscillators (1054) are provided, a frequency correction input signal (6) can be applied to the gate driver connected to each voltage-controlled oscillator (1504). At this time, the frequency of the input signal (6) output by each voltage-controlled oscillator (1054) may be different. Accordingly, the frequency of the input signal (6) applied to each gate driver may also be different.

[0204] When one voltage controlled oscillator (1054) is provided, multiple gate drivers (603) can be connected to the voltage controlled oscillator (1054) by a second switch (1056).

[0205] Depending on the operation of the second switch (1056) provided between the voltage-controlled oscillator (1054) and the plurality of gate drivers (603), input signals (6) of different frequencies can be output from the voltage-controlled oscillator (1054). Accordingly, depending on the operation of the second switch (1056), input signals (6) of different frequencies can be applied from one voltage-controlled oscillator (1054) to the plurality of gate drivers (603).

[0206] Fig. 13 is a control flowchart for operating a feedback circuit (105) in time division according to another embodiment.

[0207] According to another embodiment, the feedback circuit (105) may use one error amplifier (1053) and one voltage controlled oscillator (1054) as common elements to correct the frequency of the input signal (6) of multiple power amplifier channels (331).

[0208] At this time, the control unit (300) can control the first switch (1055) and the second switch (1056) to use one error amplifier (1053) and one voltage controlled oscillator (1054) in a time-division manner to correct the frequency of the input signal (6) of each channel.

[0209] That is, the control unit (300) can control the first switch (1055) and the second switch (1056) so that one error amplifier (1053) and one voltage controlled oscillator (1054) are connected between the first voltage sensor (1051a) and the first peak detector (1052a) connected to the first power amplifier channel (Ch1) for a preset first reference time, and the first gate driver (603a).

[0210] The control unit (300) can control the first switch (1055) and the second switch (1056) so that one error amplifier (1053) and one voltage controlled oscillator (1054) are connected between the second voltage sensor (1051b) and the second peak detector (1052b) connected to the first power amplifier channel (Ch2) for a preset second reference time, and the second gate driver (603b).

[0211] The control unit (300) can control the first switch (1055) and the second switch (1056) so that one error amplifier (1053) and one voltage controlled oscillator (1054) are connected between the third voltage sensor (1051c) and the third peak detector (1052c) connected to the third power amplifier channel (Ch1) for a preset third reference time, and the third gate driver (603c). At this time, the first reference time, the second reference time, and the third reference time may be preset and stored in the memory (320).

[0212] Specifically, the control unit (300) can control the first switch (1055) so that the first input terminal of the first switch (1055) is connected to the output terminal of the first switch (1055) (1301).

[0213] The control unit (300) can control the second switch (1056) so that the second switch (1056) operates in synchronization with the first switch (1055). Accordingly, the control unit (300) can control the second switch (1056) so that the input terminal of the second switch (1056) is connected to the first output terminal of the second switch (1056) based on the first input terminal of the first switch (1055) being connected to the output terminal of the first switch (1055) (1302).

[0214] After that, the control unit (300) can determine whether the first reference time has elapsed (1303).

[0215] The control unit (300) can maintain the operating states of the first switch (1055) and the second switch (1056) when the first reference time has not elapsed (No of 1303). That is, the control unit (300) can cause the error amplifier (1053) and the voltage controlled oscillator (1054) to be used as elements of the feedback circuit (105) for the first power amplifier channel (Ch1) during the first reference time.

[0216] On the other hand, the control unit (300) can control the first switch (1055) and the second switch (1056) to change their connection status when the first reference time has elapsed (example of 1303).

[0217] Specifically, the control unit (300) can control the first switch (1055) so that the second input terminal of the first switch (1055) is connected to the output terminal of the first switch (1055) (1304).

[0218] The control unit (300) can control the second switch (1056) so that the second switch (1056) operates in synchronization with the first switch (1055). Accordingly, the control unit (300) can control the second switch (1056) so that the input terminal of the second switch (1056) is connected to the second output terminal of the second switch (1056) based on the second input terminal of the first switch (1055) being connected to the output terminal of the first switch (1055) (1305).

[0219] After that, the control unit (300) can determine whether the second reference time has elapsed (1306).

[0220] The control unit (300) can maintain the operating states of the first switch (1055) and the second switch (1056) when the second reference time has not elapsed (NO of 1306). That is, the control unit (300) can cause the error amplifier (1053) and the voltage controlled oscillator (1054) to be used as elements of the feedback circuit (105) for the second power amplifier channel (Ch2) during the second reference time.

[0221] On the other hand, the control unit (300) can control the first switch (1055) and the second switch (1056) to change their connection status when the second reference time has elapsed (example of 1306).

[0222] Specifically, the control unit (300) can control the first switch (1055) so that the third input terminal of the first switch (1055) is connected to the output terminal of the first switch (1055) (1307).

[0223] The control unit (300) can control the second switch (1056) so that the second switch (1056) operates in synchronization with the first switch (1055). Accordingly, the control unit (300) can control the second switch (1056) so that the input terminal of the second switch (1056) is connected to the third output terminal of the second switch (1056) based on the third input terminal of the first switch (1055) being connected to the output terminal of the first switch (1055) (1308).

[0224] After that, the control unit (300) can determine whether the third reference time has elapsed (1309).

[0225] The control unit (300) can maintain the operating states of the first switch (1055) and the second switch (1056) when the third reference time has not elapsed (No of 1309). That is, the control unit (300) can cause the error amplifier (1053) and the voltage controlled oscillator (1054) to be used as elements of the feedback circuit (105) for the third power amplifier channel (Ch3) during the third reference time.

[0226] On the other hand, when the third reference time has elapsed (example of 1309), the control unit (300) determines that the frequency correction of the input signal (6) for all power amplifier channels (331) has been performed, and thus can perform control of the first switch (1055) and the second switch (1056) for frequency correction of the input signal (6) for the first power amplifier channel (Ch1) again.

[0227] Accordingly, the dryer (1) can resolve the power imbalance of all power amplifier channels (331) through switch control without having to provide all the elements of the feedback circuit (105) corresponding to the number of each power amplifier channel (331).

[0228] FIG. 14 and FIG. 15 are perspective views showing a dryer (1) having a different shape from the dryer (1) shown in FIG. 1 according to one embodiment.

[0229] Referring to FIG. 14, a dryer according to one embodiment may include a main body forming an exterior and a chamber installed inside the main body, where drying of a drying material (9) takes place. The main body forms the exterior of the dryer and may be provided in a hexahedral shape. An opening may be formed at the front of the main body through which a drying material (9) may be introduced.

[0230] The dryer (1) according to the present embodiment may include the above-described dielectric heating device (100).

[0231] The dielectric heating device (100) according to the present embodiment may include an RF power supply (102) and a feedback circuit (105) implemented as a power amplifier system including a plurality of power amplifier channels (331) that are connected in parallel with each other as described above. The RF power supply (102) and the feedback circuit (105) according to the present embodiment may include the functions, configurations, etc. described above.

[0232] That is, the control unit (300) can correct the frequency of the input signal (6) applied to each transistor (51) based on the output terminal voltage (Vds) of the plurality of transistors (51) included in the RF power supply unit (102).

[0233] The feedback circuit (105) may include a plurality of error amplifiers (1053) and a plurality of voltage-controlled oscillators (1054) corresponding to the number of transistors (51) included in the RF power supply (102).

[0234] Additionally, the feedback circuit (105) includes one error amplifier (1053), one voltage controlled oscillator (1054), a first switch (1055) and a second switch (1056), and the control unit (300) can control the first switch (1055) and the second switch (1056) to time-divisionally connect one error amplifier (1053) and one voltage controlled oscillator (1054) between the peak detector (1052) and the gate driver (603) connected to each channel.

[0235] Referring to FIG. 15, a dryer according to one embodiment may include a function for drying shoes.

[0236] For example, the article of clothing (9) may include not only clothing but also footwear (e.g., shoes, sneakers, slippers, etc.).

[0237] A dryer according to the present embodiment may include a main body constituting an outer surface, and the main body may include a door provided on the front side and opened and closed to allow shoes to enter and exit, a left side plate constituting a left side, a right side plate constituting a right side, a rear plate constituting a rear side, an upper plate constituting an upper surface, and a bottom plate constituting a bottom surface.

[0238] The dryer (1) according to the present embodiment may include a shoe receiving section for receiving the object to be dried (9), and a plurality of shoe receiving sections may be provided.

[0239] The dryer (1) according to the present embodiment may include a plurality of dielectric heating devices (100) corresponding to the number of shoe receiving portions.

[0240] The dielectric heating device (100) according to the present embodiment may include an RF power supply (102) and a feedback circuit (105) implemented as a power amplifier system including a plurality of power amplifier channels (331) that are connected in parallel with each other as described above. The RF power supply (102) and the feedback circuit (105) according to the present embodiment may include the functions, configurations, etc. described above.

[0241] That is, the control unit (300) can correct the frequency of the input signal (6) applied to each transistor (51) based on the output terminal voltage (Vds) of the plurality of transistors (51) included in the RF power supply unit (102).

[0242] The feedback circuit (105) may include a plurality of error amplifiers (1053) and a plurality of voltage-controlled oscillators (1054) corresponding to the number of transistors (51) included in the RF power supply (102).

[0243] Additionally, the feedback circuit (105) includes one error amplifier (1053), one voltage controlled oscillator (1054), a first switch (1055) and a second switch (1056), and the control unit (300) can control the first switch (1055) and the second switch (1056) to time-divisionally connect one error amplifier (1053) and one voltage controlled oscillator (1054) between the peak detector (1052) and the gate driver (603) connected to each channel.

[0244] FIG. 16 is a perspective view illustrating an oven (3) including a genetic heating device (100) according to one embodiment.

[0245] Fig. 17 is a drawing showing an oven (3) including a genetic heating device (100) according to one embodiment with the door open.

[0246] When a high-frequency electric field is applied to the food (9a), the moisture contained in the food (9a) can function as a dielectric. Accordingly, polar molecules, such as water molecules, within the food (9a) exposed to the electric field vibrate, and heat is generated due to the vibration of the polar molecules, thereby heating the food (9a). A detailed description of this will be described with reference to FIGS. 14 and 15.

[0247] Referring to FIGS. 16 and 17, an oven (3) according to one embodiment may include a main body having a cooking chamber located inside and a cooktop provided on the top of the main body on which a container containing food (9a) can be placed and heated.

[0248] The main body according to the present embodiment may include a front panel forming the front of the main body, a side panel forming the side of the main body, and a rear panel forming the rear of the main body.

[0249] The cooking chamber according to this embodiment is provided in a box shape inside the main body and can be opened at the front to allow the loading and unloading of food (9a). An opening corresponding to the cooking chamber with the open front may be provided at the front panel. The open front of the cooking chamber can be opened and closed by a door.

[0250] A plurality of supports may be provided within the cooking chamber according to the present embodiment. The plurality of supports may be equipped with racks for placing food (9a). The plurality of supports may be provided to protrude from the left and right walls of the cooking chamber.

[0251] The oven according to the present embodiment may include a plurality of electrodes (104). The plurality of electrodes (104) according to the present embodiment may include the functions, configurations, etc. described above.

[0252] An opening can be formed in the front through which a dry material (9) can be injected.

[0253] The oven (3) according to the present embodiment may include a dielectric heating device (100).

[0254] The dielectric heating device (100) according to the present embodiment may include an RF power supply (102) and a feedback circuit (105) implemented as a power amplifier system including a plurality of power amplifier channels (331) that are connected in parallel with each other as described above. The RF power supply (102) and the feedback circuit (105) according to the present embodiment may include the functions, configurations, etc. described above.

[0255] That is, the control unit (300) can correct the frequency of the input signal (6) applied to each transistor (51) based on the output terminal voltage (Vds) of the plurality of transistors (51) included in the RF power supply unit (102).

[0256] The feedback circuit (105) may include a plurality of error amplifiers (1053) and a plurality of voltage-controlled oscillators (1054) corresponding to the number of transistors (51) included in the RF power supply (102).

[0257] Additionally, the feedback circuit (105) includes one error amplifier (1053), one voltage controlled oscillator (1054), a first switch (1055) and a second switch (1056), and the control unit (300) can control the first switch (1055) and the second switch (1056) to time-divisionally connect one error amplifier (1053) and one voltage controlled oscillator (1054) between the peak detector (1052) and the gate driver (603) connected to each channel.

[0258] Meanwhile, the disclosed embodiments may be implemented in the form of a recording medium storing computer-executable instructions. The instructions may be stored in the form of program code, and when executed by a processor, may generate program modules to perform the operations of the disclosed embodiments. The recording medium may be implemented as a computer-readable recording medium.

[0259] Computer-readable storage media include all types of storage media that store instructions that can be deciphered by a computer. Examples include read-only memory (ROM), random access memory (RAM), magnetic tape, magnetic disks, flash memory, and optical data storage devices.

[0260] Additionally, a computer-readable recording 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] According to one embodiment, the method according to various embodiments disclosed in the present 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 recording 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 on a machine-readable recording 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. An RF power supply unit including a plurality of transistors connected in parallel with each other and generating an RF signal applied to a plurality of electrodes; A feedback circuit including an error amplifier that amplifies an error voltage between the output terminal voltages of the plurality of transistors and a reference voltage, and an oscillator that outputs an input signal of a frequency corrected based on the error voltage; and A dryer comprising a plurality of gate drivers that amplify the input signal of the corrected frequency output from the feedback circuit and apply the amplified signal to the plurality of transistors.

2. In paragraph 1, The above feedback circuit; A plurality of voltage sensors each connected to the plurality of transistors and detecting the output terminal voltages of the plurality of transistors, and A dryer further comprising a plurality of peak detectors, each of which is connected to the plurality of voltage sensors and converts the peak voltage of the output terminal voltages of the plurality of transistors into a DC voltage and outputs the converted voltage.

3. In paragraph 2, The above feedback circuit; A dryer further comprising a first switch connecting one of the plurality of peak detectors to the error amplifier.

4. In paragraph 3, The above feedback circuit; A dryer further comprising a second switch connecting the generator and one of the plurality of gate drivers.

5. In paragraph 4, The above dryer, A dryer further comprising a control unit that controls the connection of the first switch and the second switch based on a preset reference time.

6. In paragraph 5, The above plurality of transistors include a first transistor, a second transistor, and a third transistor, The plurality of peak detectors include a first peak detector that detects a peak voltage of the drain-source voltage of the first transistor, a second peak detector that detects a peak voltage of the drain-source voltage of the second transistor, and a third peak detector that detects a drain-source voltage of the third transistor, The above control unit; The first peak detector and the error amplifier are connected for a preset first reference time, The second peak detector and the error amplifier are connected for a preset second reference time based on the elapse of the first reference time, A dryer that controls the first switch to connect the third peak detector and the error amplifier for a preset third reference time based on the elapse of the second reference time.

7. In paragraph 6, The above control unit, A dryer that controls the first switch to connect the first peak detector and the error amplifier for a preset first reference time based on the elapse of the third reference time.

8. In paragraph 7, The above control unit; A dryer that controls the second switch by synchronizing it with the first switch.

9. In paragraph 8, The plurality of gate drivers include a first gate driver connected to the first transistor, a second gate driver connected to the second transistor, and a third gate driver connected to the third transistor, The above control unit; The oscillator and the first gate driver are connected for the first preset reference time, The oscillator and the second gate driver are connected for a preset second reference time based on the elapse of the first reference time, A dryer that controls the second switch so that the oscillator and the third gate driver are connected for a preset third reference time based on the elapse of the second reference time.

10. In paragraph 9, The above control unit, A dryer in which the generator and the first gate driver are connected and the second switch is controlled for a preset first reference time based on the elapse of the third reference time.

11. In paragraph 1, The above generator A dryer that outputs an input signal corrected to a frequency lower than a preset reference frequency based on the difference between the above error voltage and a preset threshold voltage.

12. In paragraph 2, The above voltage sensor, A dryer further comprising a voltage divider that divides the output terminal voltage of the detected plurality of transistors to the input signal level.

13. A method for controlling a dryer, comprising: an RF power supply including a first transistor, a second transistor, and a third transistor connected in parallel; a plurality of gate drivers including a first gate driver for applying an input signal to the first transistor, a second gate driver for applying an input signal to the second transistor, and a third gate driver for applying an input signal to the third transistor; a plurality of peak detectors including a first peak detector for detecting a peak voltage of an output terminal voltage of the first transistor, a second peak detector for detecting a peak voltage of an output terminal voltage of the second transistor, and a third peak detector for detecting a peak voltage of an output terminal voltage of the third transistor; an error amplifier; an oscillator; a first switch for connecting the plurality of peak detectors and the error amplifier; and a second switch for connecting the oscillator and the plurality of gate drivers, The above method of controlling the dryer is as follows: A control method for a dryer, comprising controlling the connection of the first switch and the second switch based on a preset reference time.

14. In paragraph 13, Controlling the connection of the above first switch is: The first peak detector and the error amplifier are connected for a preset first reference time, The second peak detector and the error amplifier are connected for a preset second reference time based on the elapse of the first reference time, A control method for a dryer, comprising controlling a first switch to connect the third peak detector and the error amplifier for a preset third reference time based on the elapse of the second reference time.

15. In paragraph 14, Controlling the connection of the above first switch is: A control method for a dryer, further comprising controlling a first switch to connect the first peak detector and the error amplifier for a preset first reference time based on the elapse of the third reference time.

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