Cooking apparatus

Abstract

Disclosed is a cooking apparatus in which the power of a load can be measured using a resonance current obtained by performing current conversion on a driving current supplied to the load. The cooking apparatus includes: a heating coil; a drive circuit for supplying a driving current to the heating coil according to a switching operation and outputting a resonance current and a resonance voltage obtained by performing current conversion on the driving current; a current measurement circuit for measuring the average input current of the heating coil using the resonance current and the resonance voltage; and a controller for measuring the power of the heating coil using the average input current, determining the switching frequency of the drive circuit on the basis of the measured power, and controlling the switching operation on the basis of the switching frequency.

Description

Cooking appliances

[0001] The present invention relates to a cooking appliance, and more particularly, to a cooking appliance including an induction heating cooktop.

[0002]

[0003] Induction ranges, which utilize induction heating technology, are gaining attention as next-generation cooking appliances that can replace gas ranges due to their advantages such as high heating efficiency, fast heating speed, stability, and convenience.

[0004] Induction cooktops feature heating coils made of Ritz wire. These cooktops heat induction-specific containers by placing them on a designated burner. This method requires containers to be placed in a specific location, and any slight misalignment reduces heating efficiency.

[0005] Accordingly, research and development are underway for "All Free" induction heating technology. This technology enables heating of induction containers in various locations without requiring a fixed area on the induction heating plate. It also offers the advantage of being able to heat containers of various sizes and multiple containers with three or more zones.

[0006] In multi-fired configurations, PCB pattern heating coils offer the advantages of mass production, ease of design modification, and cost reduction. However, PCB pattern heating coils have lower equivalent resistance (Req) and equivalent inductance (Leq) than Litz wire heating coils. Therefore, the inverter circuit must be capable of high-frequency operation. For this reason, inverter circuits employ SiC switches, which offer low switching losses even at high frequencies.

[0007] However, existing induction cookers measure power through a shunt resistor following a DC capacitor. This shunt resistor-based power measurement method suffers from the reliability of SiC switch operation and DESAT (Desaturation Protection) function due to noise from the resistance at the shunt ground terminal.

[0008]

[0009] The present invention provides a cooking device capable of measuring the power of a load by utilizing a resonant current obtained by converting a driving current supplied to the load into a current.

[0010] In addition, the present invention provides a cooking device capable of measuring the power of a heating coil based on resonant current and offset current by current conversion.

[0011] In addition, the present invention provides a cooking device capable of measuring the power of a heating coil by multiplying a resonant voltage by a resonant current through current conversion.

[0012] In addition, the present invention provides a cooking device capable of processing a resonant current into an input current in the form of a direct current and measuring the power of a heating coil through an average of the input current.

[0013] In addition, the present invention provides a cooking appliance capable of improving the reliability of the switch drive and DESAT (Desaturation Protection) function of an inverter circuit.

[0014] The problems to be solved according to one embodiment of this specification are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0015]

[0016] A cooking appliance according to one embodiment of the present invention measures the power of a heating coil by utilizing a current-converted resonant current.

[0017] Specifically, the cooking appliance measures the average input current of the heating coil using the resonant current resulting from current conversion of the driving current supplied to the heating coil, and measures the power of the heating coil based on the average input current.

[0018] Additionally, a cooking appliance according to one embodiment of the present invention measures the power of a heating coil based on a resonant current and an offset current by current conversion.

[0019] Specifically, the cooking appliance adds an offset current to the resonant current by current conversion of the driving current supplied to the heating coil, processes the resonant current into an average input current in the form of a direct current through a switch and capacitor that switch according to the resonant voltage, and measures the power of the heating coil based on the average input current.

[0020] In addition, a cooking appliance according to one embodiment of the present invention measures the power of a heating coil by multiplying a resonant current and a resonant voltage by current conversion.

[0021] Specifically, the cooking appliance generates a DC input current having negative current and phase information by multiplying a resonant voltage by a resonant current obtained by current conversion of a driving current supplied to a heating coil, and measures an average input current of the heating coil by averaging the DC input current.

[0022] In addition, a cooking appliance according to one embodiment of the present invention improves the reliability of the switch drive and DESAT function of the inverter circuit.

[0023] Specifically, the cooking appliance determines the switching frequency of the drive circuit based on the measured power of the heating coil, and controls the switching operation of the drive circuit based on the switching frequency.

[0024] A cooking appliance according to one embodiment of the present invention includes a heating coil that heats a container using electromagnetic induction, a driving circuit that supplies a driving current to the heating coil according to a switching drive and outputs a resonant current and a resonant voltage by current conversion of the driving current, a current measuring circuit that measures an average input current of the heating coil using the resonant current and the resonant voltage, and a controller that measures the power of the heating coil using the average input current, determines a switching frequency of the driving circuit based on the measured power, and controls the switching drive based on the switching frequency.

[0025] According to another embodiment of the present invention, a cooking appliance includes a load circuit including a heating coil, an inverter circuit for supplying a driving current to the load circuit according to a switching drive, a current converter for outputting a resonant current by current conversion of the driving current, a resonant voltage generator for outputting a resonant voltage based on the driving current, a current measuring circuit for measuring an average input current of the load circuit using the resonant current and the resonant voltage, and a controller for measuring power of the load circuit using the average input current, determining a switching frequency of the driving circuit based on the measured power, and controlling the switching drive based on the switching frequency.

[0026]

[0027] As described above, the present invention can measure the average input current by using the resonant current by current conversion of the driving current supplied to the load, and can measure the power of the load based on the average input current.

[0028] In addition, the present invention can measure the average input current of a load by processing the resonant current by converting the driving current into a DC-type average input current using the offset current and the resonant voltage.

[0029] In addition, the present invention can generate an input current having negative current and phase margin information by multiplying a resonant current and a resonant voltage by current conversion of a driving current, and can measure an average input current of a load by averaging the input current.

[0030] In addition, the present invention can process a resonant current by converting a driving current based on an offset current or a multiplier into an input current in the form of a direct current, measure an average input current through an average of the input currents, and measure the power of a load through the average input current.

[0031] In addition, the present invention can determine the switching frequency of the inverter circuit based on the power of the measured load, and can improve the reliability of the switch driving and DESAT function of the inverter circuit by controlling the switching driving of the inverter circuit based on the switching frequency.

[0032] In addition, the present invention can prevent the influence of noise due to the resistance of the ground voltage terminal by measuring the power of the load by utilizing the resonant current resulting from the current conversion of the driving current supplied to the heating coil.

[0033] In addition, the present invention can reduce the influence of noise compared to the existing technology of measuring input current using a shunt resistor, thereby improving the reliability of high-frequency driving of switching elements of an inverter circuit.

[0034] In addition, since the present invention can accurately measure the power of the load even when the container is changed to a ferromagnetic or weakly magnetic material, the heating coil can be accurately driven with the target power by switching the inverter circuit at an appropriate switching frequency depending on the container material.

[0035] In addition to the effects described above, specific effects of the present invention are described below while explaining specific details for carrying out the invention.

[0036]

[0037] FIG. 1 is an exploded perspective view showing a disassembled state of a cooktop in a cooking appliance according to one embodiment of the present invention.

[0038] Figure 2 is a drawing showing a plan view of the cooktop illustrated in Figure 1 and the configuration of the PCB pattern coil assembly.

[0039] Fig. 3 is a drawing showing the arrangement structure of the heating coil and the detection coil illustrated in Fig. 2.

[0040] Fig. 4 is a drawing showing the structure of a multilayer sensing coil PCB on which the sensing coils illustrated in Fig. 2 are arranged.

[0041] FIG. 5 is a schematic block diagram showing power measurement in a cooking appliance according to one embodiment of the present invention.

[0042] FIG. 6 is a drawing showing a driving circuit having an inverter circuit in a cooking appliance according to one embodiment of the present invention.

[0043] Fig. 7 is a waveform diagram of the resonant current output from the current converter of Fig. 6.

[0044] Fig. 8 is a waveform diagram of the resonant voltage output from the resonant voltage generator of Fig. 6.

[0045] FIG. 9 is a diagram showing an offset-based current measurement circuit according to a first embodiment of the present invention.

[0046] Fig. 10 is a waveform diagram of the first node in the offset-based current measurement circuit of Fig. 9.

[0047] Fig. 11 is a waveform diagram of the second node in the offset-based current measurement circuit of Fig. 9.

[0048] Fig. 12 is a waveform diagram of the third node in the offset-based current measurement circuit of Fig. 9.

[0049] FIG. 13 is a diagram showing a multiplier-based current measurement circuit according to a second embodiment of the present invention.

[0050] FIG. 14 is a diagram illustrating a driving circuit and a load circuit in a cooking appliance according to one embodiment of the present invention.

[0051]

[0052] The above-described objects, features, and advantages will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily practice the technical idea of ​​the present invention. In describing the present invention, if it is determined that a detailed description of known technologies related to the present invention may unnecessarily obscure the gist of the present invention, a detailed description thereof will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0053] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0054] The present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and with various modifications. However, these embodiments are provided to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention. Therefore, the present invention is not limited to the embodiments disclosed below, but should be understood to include all modifications, equivalents, and substitutes included within the technical spirit and scope of the present invention, as well as substitutions or additions of the components of one embodiment with those of another embodiment.

[0055] The attached drawings are only intended to facilitate understanding of the embodiments disclosed in this specification, and the technical ideas disclosed in this specification are not limited by the attached drawings, and should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention. In the drawings, the components may be expressed in an exaggerated size or thickness for convenience of understanding, etc., but the scope of protection of the present invention should not be construed as being limited due to this.

[0056] The terminology used in this specification is only used to describe specific implementations or examples and is not intended to limit the present invention. In addition, the singular expression includes the plural expression unless the context clearly indicates otherwise. In the specification, terms such as "comprises" and "consists of" are intended to indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification. In other words, it should be understood that terms such as "comprises" and "consists of" in the specification do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0057] Terms that include ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by these terms. These terms are used solely to distinguish one component from another.

[0058] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0059] When a component is referred to as being "above" or "below" another component, it should be understood that it is not only positioned directly above that other component, but that there may also be other components present in between.

[0060] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0061]

[0062] [Overall structure of an induction heating cooktop]

[0063] FIG. 1 is an exploded perspective view showing an exploded state of an induction heating cooktop (100) in a cooking appliance according to one embodiment of the present invention.

[0064] A cooking appliance according to one embodiment of the present invention may be an oven range type in which a cooktop (100) is positioned on the upper side and an oven section is positioned on the lower side. The present invention is not limited thereto, and may be configured as a cooking appliance in which a cooktop (100) is provided alone.

[0065] Referring to FIG. 1, a cooking appliance according to an embodiment of the present invention includes an induction heating cooktop (100). The induction heating cooktop (100) may include a case (110) and a top plate (120).

[0066] According to the present embodiment, the exterior of the cooktop (100) can be formed by a case (110) and a top plate (120). The case (110) is placed below the top plate (120) and can form the front, back, side, and bottom surfaces of the cooktop (100). The top plate (120) is placed on the top of the cooktop (100) and can form the upper exterior surface of the cooktop (100). The top plate (120) can be formed of ceramic glass for holding a cooking vessel.

[0067] A receiving space may be formed inside the case (110). The receiving space formed inside the case (110) may be opened upward. As an example, the case (110) may be formed in a hexahedral shape with an open upper side. Various internal components constituting the cooktop (100) may be accommodated in the receiving space surrounded by the top plate (120) and the case (110).

[0068] Additionally, a PCB pattern coil assembly (140) may be placed on the lower side of the top plate (120) in the cooktop (100). The PCB pattern coil assembly (140) may be formed integrally with at least one heating coil for heating a cooking vessel through induction heating and at least one detection coil for detecting the cooking vessel.

[0069] For example, the PCB pattern coil assembly (140) may be configured in multiple pieces depending on the size of the top plate (120) of the cooktop (100). For example, if the top plate (120) is divided into three left areas, a center area, and a right area, three PCB pattern coil assemblies (140) may be placed on the lower side of the corresponding areas. Each of the PCB pattern coil assemblies (140) may be formed in a different size appropriate for the sizes of the left area, the center area, and the right area. Each of the PCB pattern coil assemblies (140) corresponding to each area may be driven independently.

[0070] The PCB pattern coil assembly (140) may be formed integrally with a heating coil for induction heating, a sensing coil for container detection, a temperature sensor for temperature detection, and a terminal for connection with other components. The PCB pattern coil assembly (140) may be divided into a plurality of unit blocks. For example, one heating coil may be arranged in one unit block. For example, at least two sensing coils may be arranged in one unit block. For example, two sensing coils may be arranged between one unit block and another unit block, straddling two unit blocks.

[0071] In addition, a supporter (150) may be placed on the lower side of the PCB pattern coil assembly (140) in the cooktop (100). The supporter (150) may form a framework inside the cooktop (100) to support various internal components constituting the cooktop (100). As an example, the supporter (150) may be formed in a hexahedral shape with an open lower side. For example, the supporter (150) may be formed in a shape that is roughly a case (110) turned upside down, but may be formed to have a size slightly smaller than the case (110).

[0072] According to the present embodiment, the accommodation space can be formed inside the supporter (150), and can be formed as a space surrounded by the bottom of the case (110) and the supporter (150). Various internal components constituting the cooktop (100) can be accommodated inside the supporter (150).

[0073] For example, the inside of the supporter (190) may accommodate a resonance PCB assembly (160) in which capacitors used for resonance or oscillation are mounted, an inverter PCB assembly (170) in which switching elements for applying current to a heating coil for induction heating are mounted, a fan (180) for cooling the heat of internal components, an EMI filter (190) for filtering and blocking various noises mixed in the power supply, and a control PCB assembly in which a controller for controlling the overall operation of the cooktop (100) and circuits for container detection are mounted.

[0074] According to the present embodiment, the supporter (150) can also provide a base function of the PCB pattern coil assembly (140). More specifically, a ferrite core can be installed on the upper side of the supporter (150), the PCB pattern coil assembly (140) can be installed on the upper side of the ferrite core, and a top plate (120) can be installed on the upper side of the PCB pattern coil assembly (140).

[0075] In addition, the cooktop (100) may be equipped with a control panel (130). The control panel (130) may be placed on an area of ​​the upper surface of the top plate (120). The control panel (130) may be equipped with a user interface (UI) including a control icon for controlling the operation of the cooktop (100) by touch and a display for indicating the operating status of the cooktop (100).

[0076]

[0077] [PCB pattern coil assembly]

[0078] Fig. 2 is a drawing showing a plan view of the cooktop (100) illustrated in Fig. 1 and the configuration of the PCB pattern coil assembly (140). Fig. 3 is a drawing showing the arrangement structure of the heating coil (142) and the detection coil (143) illustrated in Fig. 2.

[0079] Referring to FIGS. 2 and 3, the cooktop (100) may include a case (110), a supporter (150), and a PCB pattern coil assembly (140). The PCB pattern coil assembly (140) is provided to configure a heating coil (142) for induction heating of the cooktop (100) and a detection coil (143) for detecting a cooking vessel, and may be placed in a receiving space inside the cooktop (100).

[0080] A supporter (150) may be placed on the upper part of the case (110), a PCB pattern coil assembly (140) may be placed on the upper part of the supporter (150), and a top plate (120) may be placed on the upper part of the PCB pattern coil assembly (140).

[0081] The PCB pattern coil assembly (140) may include a plurality of PCB pattern coil assemblies (140) depending on the size and shape of the cooktop (100). In the present embodiment, the cooktop (100) is divided into a left region, a center region, and a right region, and is exemplified by including three PCB pattern coil assemblies (140). Each PCB pattern coil assembly (140) may include a plurality of heating coils (142) and a plurality of sensing coils (143).

[0082] Each PCB pattern coil assembly (140) can be divided into a plurality of unit blocks (141). The plurality of unit blocks (141) can be arranged in a matrix form. For example, at least one heating coil (142) can be arranged in one unit block (141). For example, at least two sensing coils (143) can be arranged in one unit block (141). In addition, at least two sensing coils (143) can be arranged between one unit block (141) and another unit block (141) to span two unit blocks.

[0083] Each heating coil (142) and sensing coil (143) formed on the PCB pattern coil assembly (140) may be arranged in a pattern shape on the substrate. For example, the heating coil (142) may be formed in a polygonal, for example, square, rectangular, or hexagonal pattern. Alternatively, the heating coil (142) may be formed in a circular pattern. For example, the sensing coil (143) may be formed in a circular, square, rectangular, or hexagonal pattern.

[0084] Additionally, the PCB pattern coil assembly (140) may be formed with at least one heating coil terminal (145), at least one sensing coil terminal (146), at least one heating coil wiring (147), at least one sensing coil wiring (148), and at least one via. The heating coil terminal (145) is electrically connected to the heating coil (142) through the heating coil wiring (147) and is electrically connected to the resonant PCB assembly (160) and the inverter PCB assembly (170). The sensing coil terminal (146) is electrically connected to the sensing coil (143) through the sensing coil wiring (148) and is electrically connected to the resonant PCB assembly (160) and the control PCB assembly.

[0085] In this way, not only a heating coil (142) but also a sensing coil (143) can be formed in the unit block (141) of the PCB pattern coil assembly (140). In the unit block (141), a plurality of sensing coils (143) are arranged along the front-back direction, and a plurality of sensing coils (143) are also arranged in the lateral direction.

[0086] The PCB pattern coil assembly (140) may include a PCB having a heating coil (142) patterned thereon (hereinafter referred to as a “heating coil PCB”) and a PCB having a sensing coil (143) patterned thereon (hereinafter referred to as a “sensing coil PCB”). The PCB pattern coil assembly (140) may be formed in a form in which the heating coil PCB and the sensing coil PCB are stacked vertically. For example, the heating coil PCB may be formed in a form in which 10 to 12 layers are stacked, and the heating coils (142) between the layers may be electrically connected through vias. For example, the sensing coil PCB may be formed in a form in which two layers are stacked, and the sensing coils (143) between the layers may be electrically connected through vias.

[0087] Additionally, at least one of the heating coil PCB and the sensing coil PCB may be provided in a form in which coils are patterned on both sides of the substrate. In the present embodiment, it is exemplified that the heating coil (142) is patterned on both sides of the heating coil PCB, and the sensing coil (143) is patterned on both sides of the sensing coil PCB.

[0088] Each sensing coil (143) may be positioned to overlap with each heating coil (142) forming region, as illustrated in FIGS. 2 and 3. Additionally, each sensing coil (143) may be positioned to overlap between two adjacent heating coil (142) forming regions.

[0089] In this embodiment, it is exemplified that two sensing coils (143) are respectively arranged inside each heating coil (142) forming region, and two sensing coils (143) are respectively arranged between two heating coils (142) adjacent in the front-back direction. In addition, a temperature sensor (144) may be provided in the PCB pattern coil assembly (140). For example, the temperature sensor (144) may be arranged at the center of each sensing coil (143).

[0090] As an example, the PCB pattern coil assembly (140) may be provided in a form in which a heating coil (142), a detection coil (143), and a temperature sensor (144) are integrally formed. For example, the PCB pattern coil assembly (140) may be formed in a form in which a heating coil PCB provided with a heating coil (142) and a detection coil PCB provided with a detection coil (143) and a temperature sensor (144) are laminated. The PCB pattern coil assembly (140) may be provided in a form including one or more pattern coil PCBs.

[0091] In this way, the PCB pattern coil assembly (140) has a structure in which a plurality of heating coils (142) for induction heating using a pattern printed on the PCB and a plurality of detection coils (143) for detecting a cooking vessel placed on a ceramic glass are formed as an integral part. The number of heating coils (142) and detection coils (143) can be determined according to the size of the cooktop (100).

[0092] Fig. 4 is a drawing showing the structure of a multilayer sensing coil PCB on which the sensing coils illustrated in Fig. 2 are arranged.

[0093] As illustrated in Fig. 4, the sensing coil PCB can be laminated in multiple layers. In this embodiment, a structure in which the sensing coil PCB is laminated in two layers is exemplified.

[0094] A plurality of sensing coils (143) may be arranged on each layer of the sensing coil PCB. For example, the sensing coil PCB of each layer may include at least one heating coil terminal (145), at least one heating coil wire (147), at least one sensing coil terminal (146), at least one sensing coil wire (148), at least one via (149), and at least one temperature sensor (144).

[0095] The heating coil terminal (145) is electrically connected to the heating coil wiring (147), and the heating coil wiring (147) can be electrically connected to the heating coil (142) of the heating coil PCB through a via. In addition, the sensing coil terminal (146) is electrically connected to the sensing coil (143) through the sensing coil wiring (148), and the sensing coil (143) can be electrically connected to the sensing coil (143) of another layer through a via (149).

[0096] In this embodiment, the sensing coil (143) pattern may be printed on the PCB in a circular shape. Alternatively, the sensing coil (143) pattern may be printed on the PCB in a polygonal shape including a circular shape. The sensing coil (143) pattern may be configured as one layer (1 Layer) or multiple layers (2 Layers or more) of the entire PCB coil. When configured as multiple layers, the sensing coils (143) between layers may be electrically connected through vias (149) of the PCB. In addition, a heating coil wiring (147) connected to a heating coil terminal (145) may be located on the layer of the sensing coil (143), and may be configured separately from the heating coil (143).

[0097] In this way, in the present embodiment, the PCB pattern coil assembly (140) is configured as an integrated structure in which the heating coil (142) and the sensing coil (143) are configured as a single component using a multilayer PCB substrate, and the sensing coil (143) can be configured in a circular or polygonal shape using one or more layers.

[0098] The sensing coil (143) may be placed adjacent to a plurality of heating coils (142) or may be placed on the heating coil (142). In addition, the sensing coils (143) may be placed at equal intervals in the vertical and left-right straight lines.

[0099]

[0100] [Configuration of cooking appliances for power measurement]

[0101] FIG. 5 is a schematic block diagram showing power measurement in a cooking appliance according to one embodiment of the present invention.

[0102] In IH (Induction Heating) cookware, the output load is the induction cooker due to the nature of the application. Induction cookers are broadly categorized into ferromagnetic and weakly magnetic types, each with distinct characteristics. Cookware typically has the cooker positioned at the heating coil location, and the input power during operation is measured and the output delivered to the load is adjusted via an inverter circuit. The driving current delivered to the load can be adjusted differently for ferromagnetic and weakly magnetic cookers.

[0103] Cooking appliances can transmit higher power to the load than weakly magnetic materials under the same driving current conditions because ferromagnetic materials have relatively large equivalent resistance and equivalent inductance.

[0104] Therefore, the driving current delivered to the load from the cooking appliance must be accurately measured to accurately control the heating coil to the target power suitable for the material of the container.

[0105] Referring to FIG. 5, a cooking appliance according to one embodiment includes a control panel (130), a load circuit (350), a driving circuit (300), a container detection sensor (200), a current measurement circuit (400), and a controller (500).

[0106] The control panel (130) may be equipped with a user interface including a control icon for controlling the operation of the cooking appliance by touch and a display for indicating the operating status of the cooking appliance. The user can input a target heating intensity through the control panel (130).

[0107] The load circuit (350) includes at least one heating coil, at least one capacitor, and at least one relay. Here, the at least one heating coil, at least one capacitor, and at least one relay may be optionally connected in series or parallel.

[0108] The driving circuit (300) supplies driving current to the load circuit (350) through switching driving of the inverter circuit. The driving circuit (300) may include a current converter (330) that generates a resonant current (Ir) converted based on the driving current and a resonant voltage generator (340) that generates a resonant voltage (Vr) based on an AC voltage. The current converter (330) and the resonant voltage generator (340) may be provided within the driving circuit (300) depending on the design.

[0109] The current measurement circuit (400) can measure the input current applied to the load circuit (350) using the resonant current (Ir) and the resonant voltage (Vr), and can measure the average input current by averaging the input current.

[0110] The container detection sensor (200) detects a cooking container and provides a container detection signal based on the detection to the controller (500). The container detection sensor (200) stores oscillation energy in the detection coil (143) or outputs an oscillation signal that freely resonates according to the control of the controller (500). The container detection sensor (200) filters the DC component from the oscillation signal, compares the filtered oscillation signal with a reference signal, and outputs a container detection signal based on the comparison result to the controller (500).

[0111] The controller (500) controls the drive circuit (300) to drive the load circuit (350) with the target intensity received from the control panel (130). The controller (500) controls the switching of the switching elements of the drive circuit (300).

[0112] The controller (500) measures the power of the load circuit (350) based on the average input current received from the current measurement circuit (400), determines a switching frequency so that a target heating intensity is maintained according to the power of the load circuit (350), and controls the switching operation of the inverter circuit of the drive circuit (300) based on the switching frequency.

[0113] The controller (500) determines container information including at least one of the container location, material, shape, and size based on the container detection signal received from the container detection sensor (200). The controller (500) can control at least one relay within the load circuit (350) so that at least one heating coil corresponding to the container location is activated according to the container location.

[0114] The controller (500) can determine or vary the switching frequency for controlling the switching drive of the inverter circuit of the drive circuit (300) depending on at least one of the material, shape, and size of the container.

[0115]

[0116] [Drive circuit]

[0117] Fig. 6 is a diagram showing a driving circuit having an inverter circuit in a cooking appliance according to one embodiment of the present invention. Fig. 7 is a waveform diagram of a resonant current output from the current converter of Fig. 6. Fig. 8 is a waveform diagram of a resonant voltage output from the resonant voltage generator of Fig. 6.

[0118] Referring to FIG. 6, the driving circuit (300) includes a rectifier circuit (310) and an inverter circuit (320).

[0119] The rectifier circuit (310) converts alternating current power into direct current power. Specifically, the rectifier circuit (310) converts alternating current voltage, the magnitude and polarity of which (positive voltage or negative voltage) varies over time, into a direct current voltage, the magnitude and polarity of which are constant, and converts alternating current, the magnitude and direction of which (positive current or negative current) varies over time, into a direct current, the magnitude of which is constant.

[0120] The rectifier circuit (310) may include a bridge diode. Specifically, the rectifier circuit (310) includes four diodes (D1, D2, D3, D4). The diodes (D1, D2, D3, D4) form diode pairs (D1 and D2, D3 and D4) in which two diodes are connected in series, and the two diode pairs (D1 and D2, D3 and D4) are connected in parallel with each other. The bridge diode converts an AC voltage whose polarity changes over time into a positive voltage whose polarity is constant, and converts an AC current whose direction changes over time into a positive current whose direction is constant.

[0121] Additionally, the rectifier circuit (310) includes a DC-coupled capacitor (C1). The DC-coupled capacitor (C1) converts a positive voltage whose magnitude varies over time into a DC voltage of a constant magnitude.

[0122] The inverter circuit (320) includes a switching circuit (DS1, DS2) that supplies or cuts off a driving current to the load circuit (350). The driving current can be supplied as a resonant alternating current. The resonant frequency of the alternating current can be determined by the inductance of the heating coil and the capacitance of the resonant capacitor.

[0123] The switching circuit (DS1, DS2) includes a first switch (DS1) and a second switch (DS2), and the first switch (DS1) and the second switch (DS2) are connected in series between a high-potential voltage terminal and a low-potential voltage terminal. The low-potential voltage terminal may be a ground voltage terminal. The first switch (DS1) and the second switch (DS2) are turned on or off according to a driving control signal of the controller (500). The driving current is output to the load circuit (350) through the first switch (DS1) and / or the second switch (DS2) according to the turning on and off of the first switch (DS1) and the second switch (DS2).

[0124] The current converter (330) outputs a resonant current based on the driving current supplied from the inverter circuit (320) to the load circuit (350). The current converter (330) is disposed adjacent to an output wire through which the driving current is output. Here, the output wire is a wire connected between the node between the first switch (DS1) and the second switch (DS2) of the inverter circuit (320) and the load circuit (350). The current converter (330) converts the driving current into a resonant current having a size proportional to the driving current adjacent to the output wire. The resonant current can resonate with a constant resonant frequency over time, as illustrated in FIG. 7.

[0125] The resonant voltage generator (340) includes a first output resistor (DR1) and a second output resistor (DR2) that are connected in series between the output wire and the low-potential terminal. The resonant voltage generator (340) outputs a resonant voltage (Vr) through a node between the first output resistor (DR1) and the second output resistor (DR2). As illustrated in Fig. 8, the resonant voltage can be output in the form of a square wave depending on the resonant driving current.

[0126] Thus, the power measurement method according to the present embodiment is as shown in Fig. 6. In this specification, power is measured using an offset current-based or multiplier-based method by utilizing a current converter (330) adjacent to the output wiring from which the driving current is output, rather than a power measurement method using a shunt resistor. The power measurement method according to the present embodiment processes the resonant current into the form of an input current and measures the power delivered to the load through an average.

[0127]

[0128] [Current measurement circuit]

[0129] FIG. 9 is a diagram showing an offset-based current measurement circuit according to a first embodiment of the present invention. FIG. 10 is a waveform diagram of a first node in the offset-based current measurement circuit of FIG. 9. FIG. 11 is a waveform diagram of a second node in the offset-based current measurement circuit of FIG. 9. FIG. 12 is a waveform diagram of a third node in the offset-based current measurement circuit of FIG. 9.

[0130] <47> Figure 9 is a circuit for power measurement based on offset current of current conversion, utilizing the resonant current and resonant voltage of Figure 6. The resonant current can be processed into the form of a DC input current by switching using the resonant voltage information after taking the offset, and can be used to measure the power delivered to the load through the average.

[0131] Specifically, referring to FIGS. 9 to 12, the offset-based current measurement circuit (400) according to the first embodiment processes the resonant current (Ir) output from the current converter (330) into a direct current input current using the offset current.

[0132] The current measuring circuit (400) includes an offset circuit (410), a third switch (DS3), and a capacitor (C2). The offset circuit (410) of the current measuring circuit (400) includes a first resistor (R1) and a second resistor (R2) connected in series between a power supply voltage terminal and a ground voltage terminal.

[0133] The current measurement circuit (400) may further include a third resistor (R3). The third resistor (R3) is connected in parallel to the current converter (330), and one side is connected to a node between the first resistor (R1) and the second resistor (R2) and is connected to a first node (N1). The first node (N1) may be defined as a node where the resonance current and the offset current are added.

[0134] The offset current is output from the node between the first resistor (R1) and the second resistor (R2) of the offset circuit (410). This offset current can be added to the resonant current output from the current converter (330) at the first node (N1) via the third resistor (R3).

[0135] The current measurement circuit (400) processes the current signal of the first node (N1) by adding an offset current to the resonant current (Ir). As illustrated in Fig. 10, the current signal of the first node (N1) can be processed into a signal that resonates based on the offset current.

[0136] The current measurement circuit (400) may further include a fourth resistor (R4). One side of the fourth resistor (R4) is connected to the first node (N1) and the other side is connected to the second node (N2).

[0137] The third switch (DS3) is connected between the second node (N2) and the ground voltage terminal. The third switch (DS3) switches according to the resonance voltage (Vr). The current signal of the second node (N2) is processed according to the switching of the third switch (DS3). As illustrated in Fig. 11, the current signal of the second node (N2) becomes zero current when the third switch (DS3) is turned on by the resonance voltage (Vr), and can output the signal of the first node (N1) as the signal of the second node (N2) when the third switch (DS3) is turned off by the resonance voltage (Vr).

[0138] The current measurement circuit (400) may further include a fifth resistor (R5). One side of the fifth resistor (R5) is connected to the second node (N2) and the other side is connected to the third node (N3).

[0139] Capacitor (C2) has one side connected to the third node (N3) and the other side connected to the ground voltage terminal. Capacitor (C2) outputs the current signal of the third node (N3) as a direct current current signal.

[0140] The current signal of the third node (N3) is processed into an average input current (Iavg) having a level between the half offset (Offset / 2) current and the offset current through the capacitor (C2), as illustrated in Fig. 12. This average input current (Iavg) is provided to the controller (500). The controller (500) can measure or calculate the load power currently supplied to the load circuit (350) using the average input current (Iavg).

[0141] The power measurement method based on offset current according to the present embodiment does not lower reliability due to noise through a shunt in switches (DS1, DS2) operating at high frequencies of an inverter circuit (320), does not require the use of a shunt resistor, is robust to noise, and can normally measure load power even at high frequencies and under duty control.

[0142] Fig. 13 is a diagram illustrating a multiplier-based current measurement circuit according to a second embodiment of the present invention. Fig. 13 is a circuit for a multiplier-based power measurement method and utilizes the resonant current and resonant voltage of Fig. 6.

[0143] The current measurement circuit based on a multiplier according to the present embodiment can restore the shape of a direct current input current by multiplying a resonant current and a resonant voltage through a multiplier, and can measure the power delivered to a load through an average.

[0144] Specifically, referring to FIG. 13, a multiplier-based current measurement circuit (400a) processes the resonant current (Ir) into an average input current in the form of a direct current using a multiplier (420).

[0145] The current measurement circuit (400a) includes a multiplier (420), an operator (430), and a comparator (440). The multiplier (420) multiplies the resonant current (Ir) and the resonant voltage (Vr) to output an input current (Ir x Vr). The input current (Ir x Vr) may include negative current and phase margin information.

[0146] The calculator (430) calculates the average of the input current and outputs the average input current (Iavg) in the form of a direct current. The average input current (Iavg) is provided to the controller (500) and used to measure the load power of the load circuit (350).

[0147] A comparator (440) compares the input current (Ir x Vr) with a reference signal to extract a pulse signal (S_PM) having phase margin information. The pulse signal (S_PM) is provided to a controller (500) and used to control the phase of the driving current.

[0148] The advantages of the multiplier-based power measurement method according to the present embodiment include that the reliability is not lowered by noise through the shunt in the switches (DS1, DS2) operating at high frequencies of the inverter circuit (320), the use of a shunt resistor is unnecessary, it is robust to noise, power measurement is possible normally even at high frequencies and under duty control, and information on the phase can also be obtained.

[0149] In this way, this specification describes the contents of CT (Current Transducer) resonant current-based power control that can be utilized for high-frequency all-free IH (Induction Heating) using SiC (Silicon Carbide) MOSFET, a wide band gap element, in an inverter circuit (320).

[0150] In addition, this specification describes a CT offset current measurement method and a CT multiplier current measurement method that are robust to noise and can measure load power through CT-based resonant current even when driving SiC.

[0151] The offset current measurement method offsets the resonant current and takes the average, and the multiplier current measurement method restores the input current in the form of a multiplier voltage and a multiplier current and then measures the input power, which can contribute to improving the operational reliability of high-frequency switch elements in the inverter circuit.

[0152] FIG. 14 is a diagram illustrating a driving circuit and a load circuit in a cooking appliance according to one embodiment of the present invention.

[0153] Referring to FIG. 14, in a cooking appliance according to one embodiment, the driving circuit includes a rectifier circuit (310) and an inverter circuit (320a, 320b).

[0154] The inverter circuit (320a, 320b) includes a first inverter circuit (320a) that supplies a first driving current to a load circuit (350) according to switching driving, and a second inverter circuit (320b) that supplies a second driving current to the load circuit (350) according to switching driving.

[0155] The load circuit (350) may include at least one capacitor (CS1, CS2, CS3, CS4, CS5, CS6, CS7, CS8) connected in series or in parallel, at least one heating coil (WC1, WC2, WC3, WC4, WC5, WC6, WC7, WC8), and at least one relay (RL1, RL2, RL3, RL4, RL4, RL6).

[0156] Capacitors (CS1, CS2, CS3, CS4, CS5, CS6, CS7, CS8) can be used to filter the DC component in the driving current. Heating coils (WC1, WC2, WC3, WC4, WC5, WC6, WC7, WC8) can be used to heat the cooking vessel using electromagnetic induction. Relays (RL1, RL2, RL3, RL4, RL4, RL6) can be used to selectively connect the heating coils (WC1, WC2, WC3, WC4, WC5, WC6, WC7, WC8) in series or parallel. Additionally, the heating coils (WC1, WC2, WC3, WC4, WC5, WC6, WC7, WC8) and capacitors (CS1, CS2, CS3, CS4, CS5, CS6, CS7, CS8) can be used to determine the resonant frequency of the driving current.

[0157] The load circuit (350) may include a first capacitor (CS1) that transmits a first driving current supplied from a first inverter circuit (320a), a first heating coil (WC1) connected in series to the first capacitor (CS1), a second heating coil (WC2) connected in series to the first heating coil (WC1), a second capacitor (CS2) connected in series to the second heating coil (WC2), and a first relay (RL1) that switches the second capacitor (CS2) and a ground voltage terminal.

[0158] In addition, the load circuit (350) may further include a third capacitor (CS3) that transmits a second driving current supplied from a second inverter circuit (320b), a third heating coil (WC3) connected in series to the third capacitor (CS3), a fourth heating coil (WC4) connected in series to the third heating coil (WC3), a fourth capacitor (CS4) connected in series to the fourth heating coil (WC4), and a second relay (RL2) that switches the fourth capacitor (CS4) and a ground voltage terminal.

[0159] Additionally, the load circuit (350) may further include a third relay (RL3) that switches a node between the first heating coil (WC1) and the second heating coil (WC2) and a node between the third heating coil (WC3) and the fourth heating coil (WC4).

[0160] In addition, the load circuit (350) may further include a fifth capacitor (CS5) that transmits a first driving current supplied from the first inverter circuit (320a), a fifth heating coil (WC5) connected in series to the fifth capacitor (CS5), a sixth heating coil (WC6) connected in series to the fifth heating coil (WC5), a sixth capacitor (CS6) connected in series to the sixth heating coil (WC6), and a fourth relay (RL4) that switches the sixth capacitor (CS6) and a ground voltage terminal.

[0161] In addition, the load circuit (350) may further include a seventh capacitor (CS7) that transmits a second driving current supplied from a second inverter circuit (320b), a seventh heating coil (WC7) connected in series to the seventh capacitor (CS7), an eighth heating coil (WC8) connected in series to the seventh heating coil (WC7), an eighth capacitor (CS8) connected in series to the eighth heating coil (WC7), and a fifth relay (RL5) that switches the eighth capacitor (CS8) and a ground voltage terminal.

[0162] Additionally, the load circuit (350) may further include a sixth relay (RL6) that switches a node between the fifth heating coil (WC5) and the sixth heating coil (WC6) and a node between the seventh heating coil (WC7) and the eighth heating coil (WC8).

[0163] A cooking appliance according to one embodiment of the present specification may include a heating coil that heats a container using electromagnetic induction, a driving circuit that supplies a driving current to the heating coil according to a switching drive and outputs a resonant current and a resonant voltage by current conversion of the driving current, a current measuring circuit that measures an average input current of the heating coil using the resonant current and the resonant voltage, and a controller that measures power of the heating coil using the average input current, determines a switching frequency of the driving circuit based on the measured power, and controls the switching drive based on the switching frequency.

[0164] According to one embodiment, the drive circuit may include an inverter circuit that supplies a drive current to the heating coil according to a switching drive, a current converter that outputs a resonant current based on the drive current output from the inverter circuit, and a resonant voltage generator that outputs a resonant voltage based on the drive current output from the inverter circuit.

[0165] According to one embodiment, the inverter circuit may include a first switch and a second switch connected in series between a high potential terminal and a low potential terminal, and an output wire connected to a node between the first switch and the second switch.

[0166] In one embodiment, the current converter is positioned adjacent to the output wiring and is capable of converting the driving current into a resonant current having a magnitude proportional to the driving current.

[0167] According to one embodiment, the resonant voltage generator may include a first output resistor and a second output resistor connected in series between an output wire and a low-potential terminal. The resonant voltage generator may output a resonant voltage in the form of a square wave based on a driving current through a node between the first output resistor and the second output resistor.

[0168] In one embodiment, the current measurement circuit can process the resonant current of the current converter into an average input current in the form of a direct current using the offset current.

[0169] According to one embodiment, the current measurement circuit may include a first resistor and a second resistor connected in series between a power supply voltage terminal and a ground voltage terminal, and an offset circuit outputting an offset current through a node between the first resistor and the second resistor, a third resistor connected in parallel to the current converter and having one side connected to a node between the first resistor and the second resistor and a first node connected to the current converter and the other side connected to the current converter, a fourth resistor having one side connected to the first node and the other side connected to the second node, a third switch connected between the second node and the ground voltage terminal and switching according to a resonance voltage, a fifth resistor having one side connected to the second node and the other side connected to the third node, and a capacitor having one side connected to the third node and the other side connected to the ground voltage terminal.

[0170] According to one embodiment, the current measurement circuit processes a current signal of a first node by adding an offset current to a resonant current, processes a current signal of a second node according to the switching of a third switch, processes the current signal of the third node into an average input current through a capacitor, and provides the average input current to the controller.

[0171] In one embodiment, the current measurement circuit can process the resonant current of the current transformer into an average input current in direct current form using a multiplier.

[0172] According to one embodiment, the current measurement circuit may include a multiplier that multiplies a resonant current and a resonant voltage to output an input current including a negative current and phase margin information, an operator that averages the input currents to output an average input current, and a comparator that compares the input current with a reference signal to extract a pulse signal having phase margin information and provides the pulse signal to a controller.

[0173] A cooking appliance according to one embodiment of the present specification may include a load circuit including a heating coil, an inverter circuit for supplying a driving current to the load circuit according to a switching drive, a current converter for outputting a resonant current by current conversion of the driving current, a resonant voltage generator for outputting a resonant voltage based on the driving current, a current measuring circuit for measuring an average input current of the load circuit using the resonant current and the resonant voltage, and a controller for measuring power of the load circuit using the average input current, determining a switching frequency of the driving circuit based on the measured power, and controlling the switching drive based on the switching frequency.

[0174] According to one embodiment, the inverter circuit may include a first inverter circuit and a second inverter circuit that supply a first driving current and a second driving current to a load circuit according to a switching operation.

[0175] According to one embodiment, the current converter may include a first current converter that outputs a first resonant current based on a first driving current output from a first inverter circuit, and a second current converter that outputs a second resonant current based on a third driving current output from a second inverter circuit.

[0176] According to one embodiment, the resonant voltage generator may include a first resonant voltage generator that outputs a first resonant voltage based on a first driving current of the first inverter circuit, and a second resonant voltage generator that outputs a second resonant voltage based on a second driving current of the second inverter circuit.

[0177] According to one embodiment, the current measurement circuit can process the first resonant current or the second resonant current of the first current converter or the second current converter into an average input current in the form of a direct current using a preset offset current and a resonant voltage.

[0178] According to one embodiment, the current measurement circuit can process the first resonant current or the second resonant current of the first current converter or the second current converter into an average input current in the form of a direct current by using a multiplier that performs a multiplication operation on the resonant current and the resonant voltage.

[0179] According to one embodiment, the load circuit may include at least one capacitor, at least one heating coil, and at least one relay connected in series or parallel.

[0180] According to one embodiment, the load circuit may include a first capacitor for transmitting a first driving current supplied from a driving circuit, a first heating coil connected in series with the first capacitor, a second heating coil connected in series with the first heating coil, a second capacitor connected in series with the second heating coil, and a first relay for switching between the second capacitor and a ground voltage terminal.

[0181] According to one embodiment, the load circuit may further include a third capacitor for transmitting a second driving current supplied from the driving circuit, a third heating coil connected in series with the third capacitor, a fourth heating coil connected in series with the third heating coil, a fourth capacitor connected in series with the fourth heating coil, and a second relay for switching between the fourth capacitor and a ground voltage terminal.

[0182] According to one embodiment, the load circuit may further include a third relay that switches a node between the first heating coil and the second heating coil and a node between the third heating coil and the fourth heating coil.

[0183] According to one embodiment, the load circuit may further include a fifth capacitor for transmitting a first driving current supplied from the driving circuit, a fifth heating coil connected in series with the fifth capacitor, a sixth heating coil connected in series with the fifth heating coil, a sixth capacitor connected in series with the sixth heating coil, and a fourth relay for switching between the sixth capacitor and a ground voltage terminal.

[0184] According to one embodiment, the load circuit may further include a seventh capacitor for transmitting a second driving current supplied from the driving circuit, a seventh heating coil connected in series with the seventh capacitor, an eighth heating coil connected in series with the seventh heating coil, an eighth capacitor connected in series with the eighth heating coil, and a fifth relay for switching between the eighth capacitor and a ground voltage terminal.

[0185] According to one embodiment, the load circuit may further include a sixth relay that switches a node between the fifth heating coil and the sixth heating coil and a node between the seventh heating coil and the eighth heating coil.

[0186] While the present invention has been described with reference to the embodiments illustrated in the drawings, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent embodiments are possible. Accordingly, the true technical protection scope of the present invention should be defined by the following claims.

Claims

1. A heating coil that heats the container using electromagnetic induction; A driving circuit that supplies a driving current to the heating coil according to a switching drive and outputs a resonance current and a resonance voltage by current conversion of the driving current; A current measuring circuit that measures the average input current of the heating coil using the resonant current and the resonant voltage; and A cooking appliance comprising a controller that measures the power of the heating coil using the average input current, determines the switching frequency of the driving circuit based on the measured power, and controls the switching drive based on the switching frequency.

2. In paragraph 1, The above driving circuit An inverter circuit that supplies driving current to the heating coil according to the switching drive; A current converter that outputs a resonant current based on the driving current output from the inverter circuit; and A cooking appliance comprising a resonant voltage generator that outputs a resonant voltage based on the driving current output from the inverter circuit.

3. In paragraph 2, The above inverter circuit A first switch and a second switch connected in series between a high-potential terminal and a low-potential terminal; and A cooking appliance comprising an output wiring connected to a node between the first switch and the second switch.

4. In paragraph 3, The above current converter A cooking appliance arranged adjacent to the output wiring and converting the driving current into the resonant current having a size proportional to the driving current.

5. In paragraph 4, The above resonant voltage generator A cooking appliance comprising a first output resistor and a second output resistor connected in series between the output wiring and the low-potential terminal, and outputting the resonant voltage in the form of a square wave based on the driving current through a node between the first output resistor and the second output resistor.

6. In paragraph 2, The above current measurement circuit A cooking appliance that processes the resonant current of the current converter into the average input current in the form of a direct current by using an offset current.

7. In paragraph 6, The above current measurement circuit An offset circuit including a first resistor and a second resistor connected in series between a power voltage terminal and a ground voltage terminal, and outputting an offset current through a node between the first resistor and the second resistor; A third resistor connected in parallel to the current converter, one side of which is connected to a node between the first resistor and the second resistor and the current converter, and the other side of which is connected to a first node connected to the current converter; A fourth resistor having one end connected to the first node and the other end connected to the second node; A third switch connected between the second node and the ground voltage terminal and switching according to the resonant voltage; A fifth resistor having one end connected to the second node and the other end connected to the third node; and A capacitor having one side connected to the third node and the other side connected to the ground voltage terminal; A cooking appliance, including:

8. In paragraph 7, The above current measurement circuit A cooking appliance that processes the current signal of the first node by adding the offset current to the resonant current, processes the current signal of the second node according to the switching of the third switch, processes the current signal of the third node into the average input current through the capacitor, and provides the average input current to the controller.

9. In paragraph 2, The above current measurement circuit A cooking appliance that processes the resonant current of the current converter into the average input current in the form of a direct current using a multiplier.

10. In paragraph 9, The above current measurement circuit A multiplier that performs a multiplication operation on the resonant current and the resonant voltage to output an input current including negative current and phase margin information; An operator that calculates the average of the input current and outputs the average input current; and A cooking appliance comprising a comparator that compares the input current and a reference signal to extract a pulse signal having phase margin information and provides the pulse signal to the controller.

11. Load circuit including heating coil; An inverter circuit that supplies driving current to the load circuit according to switching drive; A current converter that outputs a resonant current by converting the above driving current; A resonant voltage generator that outputs a resonant voltage based on the driving current; A current measuring circuit that measures the average input current of the load circuit using the resonant current and the resonant voltage; and A cooking appliance comprising a controller that measures the power of the load circuit using the average input current, determines the switching frequency of the driving circuit based on the measured power, and controls the switching drive based on the switching frequency.

12. In paragraph 11, The above inverter circuit A cooking appliance comprising a first inverter circuit and a second inverter circuit that supply a first driving current and a second driving current to the load circuit according to the switching drive.

13. In paragraph 12, The above current converter A first current converter that outputs a first resonant current based on the first driving current output from the first inverter circuit; and A cooking appliance comprising a second current converter that outputs a second resonant current based on the third driving current output from the second inverter circuit.

14. In paragraph 13, The resonant voltage generator is a first resonant voltage generator that outputs a first resonant voltage based on the first driving current of the first inverter circuit; and A cooking appliance comprising a second resonant voltage generator that outputs a second resonant voltage based on the second driving current of the second inverter circuit.

15. In paragraph 14, A cooking appliance in which the current measuring circuit processes the first resonant current or the second resonant current of the first current converter or the second current converter into the average input current in the form of a direct current using a preset offset current and the resonant voltage.

16. In paragraph 15, A cooking appliance in which the current measuring circuit processes the first resonant current or the second resonant current of the first current converter or the second current converter into the average input current in the form of a direct current using a multiplier that performs a multiplication operation on the resonant current and the resonant voltage.

17. In paragraph 11, The above load circuit A cooking appliance comprising at least one capacitor, at least one heating coil and at least one relay connected in series or parallel.

18. In paragraph 11, The above load circuit A first capacitor that transmits a first driving current supplied from a first inverter circuit of the above driving circuit; A first heating coil connected in series to the first capacitor; A second heating coil connected in series to the first heating coil; A second capacitor connected in series with the second heating coil; It includes a first relay that switches the second capacitor and the ground voltage terminal, The above load circuit A third capacitor that transmits a second driving current supplied from a second inverter circuit of the above driving circuit; A third heating coil connected in series to the third capacitor; A fourth heating coil connected in series to the third heating coil; A fourth capacitor connected in series with the fourth heating coil; It further includes a second relay that switches the fourth capacitor and the ground voltage terminal, The above load circuit A cooking appliance further comprising a third relay for switching a node between the first heating coil and the second heating coil and a node between the third heating coil and the fourth heating coil.

19. In paragraph 18, The above load circuit A fifth capacitor that transmits the first driving current supplied from the first inverter circuit of the driving circuit; A fifth heating coil connected in series to the fifth capacitor; A sixth heating coil connected in series to the fifth heating coil; A sixth capacitor connected in series with the sixth heating coil; It further includes a fourth relay that switches the sixth capacitor and the ground voltage terminal, The above load circuit A seventh capacitor that transmits the second driving current supplied from the second inverter circuit of the driving circuit; A seventh heating coil connected in series to the seventh capacitor; An eighth heating coil connected in series to the seventh heating coil; An eighth capacitor connected in series to the eighth heating coil; A cooking appliance further comprising a fifth relay for switching the eighth capacitor and the ground voltage terminal.

20. In paragraph 19, The above load circuit A cooking appliance further comprising a sixth relay for switching a node between the fifth heating coil and the sixth heating coil and a node between the seventh heating coil and the eighth heating coil.

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