Cooking appliance

Abstract

A cooking device according to an embodiment of the present disclosure may include a top plate on which an object to be heated is placed, an intermediate heating element disposed on the top plate, a plurality of working coils that generate a magnetic field coupled to at least one of the object to be heated and the intermediate heating element, an inverter unit that applies current to the plurality of working coils, and a controller that controls the inverter unit so that at least one of the plurality of working coils does not operate during at least a portion of a cycle when operating in a first heating mode.

Description

Technology Field

[0001] The present disclosure relates to a cooking appliance. More specifically, the present disclosure relates to a cooking appliance capable of heating both magnetic and non-magnetic materials. Background Technology

[0003] Various types of cooking appliances are used to heat food in homes and restaurants. Traditionally, gas ranges using gas as fuel have been widely used; however, recently, devices that heat objects using electricity instead of gas—such as cooking vessels like pots—are becoming more popular.

[0004] Methods of heating an object using electricity are broadly divided into resistance heating and induction heating. The electric resistance method heats an object by transferring heat generated when an electric current is passed through a metal resistance wire or a non-metallic heating element, such as silicon carbide, to the object (e.g., a cooking vessel) through radiation or conduction. The induction heating method, on the other hand, is a method in which an eddy current is generated in an object made of metal components by utilizing the magnetic field generated around a coil when high-frequency power of a predetermined magnitude is applied to the coil, thereby heating the object itself.

[0005] Recently, induction heating methods are being applied to most cooking appliances.

[0006] Meanwhile, such cooking appliances have a limitation in that their heating efficiency for non-magnetic containers is very low compared to their heating efficiency for magnetic containers. Accordingly, to improve the problem of very low heating efficiency for non-magnetic materials (e.g., heat-resistant glass, ceramics, etc.), the cooktop includes an intermediate heating element to which eddy currents are applied, and can heat non-magnetic materials through this intermediate heating element.

[0007] However, when an intermediate heating element is provided in a cooking appliance in this manner, there is a problem in that heating efficiency is somewhat reduced because, when heating a magnetic container, some of the magnetic field combines with the intermediate heating element before reaching the magnetic container, resulting in indirect heating. The problem to be solved

[0009] The present disclosure aims to provide a cooking device capable of heating magnetic, non-magnetic, and non-metallic containers regardless of the container material.

[0010] The present disclosure aims to minimize the problem of reduced heating efficiency for a magnetic container in a cooking appliance including an intermediate heating element.

[0011] The present disclosure aims to provide a cooking device that controls the amount of heat generated in an intermediate heating element according to the type of object to be heated.

[0012] The present disclosure aims to improve the ease of use of a cooking appliance including an intermediate heating element. means of solving the problem

[0014] The present disclosure can control the amount of heat generated in an intermediate heating element by controlling the operation of a plurality of working coils.

[0015] The present disclosure can reduce the amount of heat generated in an intermediate heating element and increase the amount of heat generated in the container itself by controlling that a plurality of working coils do not operate simultaneously for at least a portion of the time when heating a magnetic container.

[0016] A cooking device according to an embodiment of the present disclosure may include a top plate on which an object to be heated is placed, an intermediate heating element disposed on the top plate, a plurality of working coils that generate a magnetic field coupled to at least one of the object to be heated and the intermediate heating element, an inverter unit that applies current to the plurality of working coils, and a controller that controls the inverter unit so that at least one of the plurality of working coils does not operate during at least a portion of a cycle when operating in a first heating mode.

[0017] A plurality of working coils includes at least a first and a second working coil, and the controller can control the inverter section so that for half of a cycle, only the first working coil operates, and for the remaining half, only the second working coil operates.

[0018] The cycle may include a section where only the first working coil operates, a section where only the second working coil operates, and a section where the first working coil and the second working coil operate together.

[0019] The controller can control the inverter section so that only the first working coil operates during the first section of a cycle, the first working coil and the second working coil operate together during the second section after the first section, and only the second working coil operates during the third section after the second section.

[0020] The time corresponding to each of the first to third intervals may be the same.

[0021] The controller can adjust the operating frequency of the inverter section so that multiple working coils produce maximum output when operating in the first heating mode.

[0022] The controller can operate in a first heating mode when the object to be heated is a magnetic material.

[0023] The controller can control the inverter section so that all multiple working coils operate during one cycle when operating in the second heating mode.

[0024] The controller can operate in a second heating mode when the object to be heated is a non-magnetic material.

[0025] The intermediate heating element may be arranged to overlap vertically with at least two of the plurality of working coils.

[0026] The intermediate heating element can be positioned to overlap vertically with some of the multiple working coils.

[0027] If a plurality of heating zones are pre-designated in the upper plate, an intermediate heating element may be installed at a position corresponding to any one of the plurality of heating zones.

[0028] If a heating zone is not pre-designated in the upper plate, the intermediate heating element may be installed at a position corresponding to the center of a plurality of working coils.

[0029] If a heating zone is not pre-designated in the top plate, the intermediate heating element may be installed in a position where at least a portion overlaps vertically with the working coil positioned closest to the apex of the top plate. Effects of the invention

[0031] According to an embodiment of the present disclosure, by controlling the heat output of an intermediate heating element according to the type of object to be heated, there is an advantage of improving heating efficiency by container material and increasing output performance.

[0032] According to an embodiment of the present disclosure, there is an advantage in that the control logic can be simplified in order to improve output performance by selectively operating a plurality of working coils during one cycle without the need to control the phase of a plurality of working coils.

[0033] According to an embodiment of the present disclosure, since the heating zone is not designated, the freedom of the container is improved, and at the same time, when heating an object to be heated placed at the installation location of an intermediate heating element, there is an advantage that heating can be done with high efficiency regardless of the container material. Brief explanation of the drawing

[0035] FIG. 1 is a perspective view showing a cooking appliance according to one embodiment of the present disclosure. FIG. 2 is a circuit diagram of a cooking appliance according to one embodiment of the present disclosure. FIG. 3 is a cross-sectional view showing a cooking device and a heated object according to one embodiment of the present disclosure. FIG. 4 is a cross-sectional view showing a cooking device and a heated object according to another embodiment of the present disclosure. FIG. 5 is a drawing showing an intermediate heating element and a plurality of working coils according to a first embodiment of the present disclosure. FIG. 6 is a drawing showing an intermediate heating element and a plurality of working coils according to a second embodiment of the present disclosure. FIG. 7 is a drawing showing an intermediate heating element and a plurality of working coils according to a third embodiment of the present disclosure. FIG. 8 is a drawing showing an intermediate heating element and a plurality of working coils according to a fourth embodiment of the present disclosure. FIG. 9 is a drawing showing the output when the working coils of a cooktop according to an embodiment of the present disclosure operate simultaneously. FIG. 10 is a drawing showing the output when the working coil of a cooktop according to an embodiment of the present disclosure operates alternately in a first manner. FIG. 11 is a drawing showing the output when the working coil of a cooktop according to an embodiment of the present disclosure operates alternately in a second manner. FIG. 12 is a control block diagram for explaining the operation method of a cooktop according to an embodiment of the present disclosure. Specific details for implementing the invention

[0036] Hereinafter, preferred embodiments according to the present disclosure will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0037] The suffixes "module" and "part" used for components in the following description are assigned or used interchangeably solely for the ease of drafting the specification, and do not inherently possess distinct meanings or roles.

[0038] In the following description, being “connected” between components includes not only direct connection between components but also indirect connection through at least one other component, unless otherwise specified.

[0039] Hereinafter, a cooking appliance and a method of operation thereof according to an embodiment of the present disclosure will be described. Hereinafter, the cooking appliance may be an induction heating type cooktop.

[0041] Hereinafter, a cooking appliance according to an embodiment of the present disclosure will be described.

[0042] FIG. 1 is a perspective view showing a cooking device according to one embodiment of the present disclosure. FIG. 2 is a circuit diagram of a cooking device according to one embodiment of the present disclosure. FIG. 3 is a cross-sectional view showing a cooking device and an object to be heated according to one embodiment of the present disclosure. FIG. 4 is a cross-sectional view showing a cooking device and an object to be heated according to another embodiment of the present disclosure.

[0043] First, referring to FIG. 1, a cooking device (1) according to an embodiment of the present disclosure may include a case (25), a cover plate (20), a working coil (WC), and an intermediate heating element (IM).

[0044] A working coil (WC) can be installed in the case (25).

[0045] For reference, in addition to the working coil (WC), the case (25) may be equipped with various devices related to the operation of the working coil (e.g., a power supply unit (110, see FIG. 2) that provides AC power, a rectifier unit (120, see FIG. 2) that rectifies the AC power from the power supply unit into DC power, an inverter unit (140, see FIG. 2) that converts the DC power rectified by the rectifier unit into a resonant current through a switching operation and provides it to the working coil, a control module (not shown) that controls the operation of various devices within the cooking appliance (1), etc.).

[0046] The cover plate (20) is coupled to the top of the case (25), and may be provided with a top plate (15) on which a heated object (not shown) is placed on the top surface.

[0047] Specifically, the cover plate (20) may include a top plate (15) for placing an object to be heated, such as a cooking vessel. That is, an object to be heated may be placed on the top plate (15).

[0048] Here, the top plate (15) may be made of, for example, a glass material (e.g., ceramic glass). However, this is merely an example and is not limited thereto, and the material of the top plate (15) may vary.

[0049] Additionally, the top plate (15) may be equipped with an input interface (not shown) that receives input from a user and transmits the input to a control module (not shown) for an input interface. Of course, the input interface may be provided at a location other than the top plate (15).

[0050] For reference, the input interface is a module for inputting the heating intensity or the operating time of the cooking device (1) desired by the user, and can be implemented in various ways, such as physical buttons or touch panels. In addition, the input interface may be equipped with, for example, a power button, a lock button, power level adjustment buttons (+, -), timer adjustment buttons (+, -), and a charging mode button. Furthermore, the input interface transmits the input provided by the user to a control module for the input interface (not shown), and the control module for the input interface transmits the input to the aforementioned control module (i.e., the control module for the inverter). In addition, the aforementioned control module can control the operation of various devices (e.g., a working coil) based on the input provided by the control module for the input interface (i.e., the user's input), and specific details regarding this are omitted.

[0051] Meanwhile, on the top plate (15), the operation status of the working coil (WC) and the heating intensity (i.e., heat power) can be visually displayed in the shape of a fireball. This fireball shape can be displayed by an indicator (not shown) composed of a plurality of light-emitting elements (e.g., LEDs) provided within the case (25).

[0052] A working coil (WC) can be installed inside a case (25) to heat an object to be heated.

[0053] Specifically, the working coil (WC) can be driven by the aforementioned control module (not shown), and when a heated object is placed on the upper plate (15), it can be driven by the control module.

[0054] In addition, the working coil (WC) can directly heat a magnetic object to be heated (i.e., a magnetic material) and can indirectly heat a non-magnetic object to be heated (i.e., a non-magnetic material) through an intermediate heating element (IM).

[0055] In addition, the working coil (WC) can heat the object to be heated by an induction heating method and can be provided to overlap with the intermediate heating element (IM) in a vertical direction (i.e., vertical direction or up and down direction).

[0056] For reference, FIG. 1 is illustrated as having one working coil (WC) installed in the case (25), but it is not limited thereto. That is, one or more working coils (WC) may be installed in the case (25). An intermediate heating element (IM) may be installed to correspond to the working coil (WC).

[0057] An intermediate heating element (IM) may be installed on the top plate (15). The intermediate heating element (IM) may be coated on the top plate (15) to heat a non-magnetic object among the objects to be heated. The intermediate heating element (IM) may be inductively heated by a working coil (WC).

[0058] An intermediate heating element (IM) may be formed on the upper or lower surface of the upper plate (15). For example, as shown in FIG. 3, the intermediate heating element (IM) may be installed on the upper surface of the upper plate (15), or as shown in FIG. 4, the intermediate heating element (IM) may be installed on the lower surface of the upper plate (15).

[0059] The intermediate heating element (IM) may be provided to overlap the working coil (WC) in a longitudinal direction (i.e., vertical or up-and-down direction). Accordingly, heating of the object to be heated is possible regardless of the placement position and type of the object to be heated.

[0060] In addition, the intermediate heating element (IM) may have at least one of magnetic and non-magnetic properties (i.e., magnetic, non-magnetic, or both magnetic and non-magnetic).

[0061] In addition, the intermediate heating element (IM) may be made of, for example, a conductive material (e.g., aluminum) and may be installed on the upper plate (15) in a shape in which multiple rings of different diameters are repeated, as shown in the drawing, but is not limited thereto. That is, the intermediate heating element (IM) may be made of a material other than a conductive material. In addition, the intermediate heating element (IM) may be formed in a shape other than a shape in which multiple rings of different diameters are repeated.

[0062] For reference, Figures 3 and 4 show one intermediate heating element (IM), but are not limited thereto. That is, multiple intermediate heating elements may be installed, but for the convenience of explanation, the installation of one intermediate heating element (IM) will be used as an example for the explanation.

[0063] FIG. 2 is a circuit diagram of a cooking appliance according to one embodiment of the present disclosure.

[0064] Referring to FIG. 2, the cooking device may include at least some or all of a power supply unit (110), a rectifier unit (120), a DC link capacitor (130), an inverter unit (140), a working coil (WC), and a resonant capacitor (160).

[0065] The power supply unit (110) can receive external power. The power received by the power supply unit (110) from the outside may be AC ​​(Alternation Current) power.

[0066] The power supply unit (110) can supply alternating current voltage to the rectifier unit (120).

[0067] The rectifier (120) is an electrical device for converting alternating current into direct current. The rectifier (120) converts the alternating current voltage supplied through the power supply (110) into a direct current voltage. The rectifier (120) can supply the converted voltage to the DC terminals (121).

[0068] The output terminal of the rectifier (120) can be connected to the DC terminal (121). The DC terminal (121) output through the rectifier (120) can be called a DC link. The voltage measured at the DC terminal (121) is called the DC link voltage.

[0069] The DC link capacitor (130) serves as a buffer between the power supply unit (110) and the inverter unit (140). Specifically, the DC link capacitor (130) is used to maintain the DC link voltage converted through the rectifier unit (120) and supply it to the inverter unit (140).

[0070] The inverter unit (140) serves to switch the voltage applied to the working coil (WC) so that a high-frequency current flows through the working coil (WC). The inverter unit (140) can apply current to the working coil (WC). The inverter unit (140) may include a relay or a semiconductor switch, etc., for turning on or off the working coil (WC). For example, the inverter unit (140) may include a semiconductor switch, and the semiconductor switch may be an IGBT (Insulated Gate Bipolar Transistor) or WBG (Wide Band Gab) device, but since this is merely exemplary, it is reasonable not to limit it thereto. Meanwhile, the WBG device may be SiC (Silicon Carbide) or GaN (Gallium Nitride), etc. By driving the semiconductor switch, the inverter unit (140) causes a high-frequency current to flow through the working coil (WC), and accordingly, a high-frequency magnetic field is formed in the working coil (WC).

[0071] A working coil (WC) may include at least one working coil (WC) that generates a magnetic field to heat an object to be heated (HO). The working coil (WC) may have current flowing through it or not flow through it depending on whether the switching element is driven. When current flows through the working coil (WC), a magnetic field is generated. The working coil (WC) can generate a magnetic field as current flows to heat the cooking appliance.

[0072] One side of the working coil (WC) is connected to the connection point of the switching element of the inverter section (140), and the other side is connected to the resonant capacitor (160).

[0073] The switching element is driven by a driving unit (not shown), and the switching elements are controlled by the switching time output from the driving unit, and the switching elements operate alternately to apply a high-frequency voltage to the working coil (WC). Also, since the on / off time of the switching element applied from the driving unit (not shown) is controlled in a gradually compensated manner, the voltage supplied to the working coil (WC) changes from a low voltage to a high voltage.

[0074] The resonant capacitor (160) can resonate with the working coil of the working coil (WC).

[0075] The resonant capacitor (160) may be a component to serve as a buffer. The resonant capacitor (160) controls the saturation voltage rise rate during the turn-off of the switching element, thereby affecting energy loss during the turn-off time.

[0076] Next, referring to FIGS. 3 and 4, a cooking device (1) according to one embodiment of the present disclosure may further include at least some or all of an insulating material (35), a shielding plate (45), a support member (50), and a cooling fan (55).

[0077] Insulating material (35) can be provided between the top plate (15) and the working coil (WC).

[0078] Specifically, the insulation material (35) can be mounted below the top plate (15), and a working coil (WC) can be placed below it.

[0079] These insulating materials (35) can block heat generated as the intermediate heating element (IM) or object to be heated (HO) is heated by the driving of the working coil (WC) from being transferred to the working coil (WC).

[0080] That is, when an intermediate heating element (IM) or a heated object (HO) is heated by electromagnetic induction of a working coil (WC), the heat from the intermediate heating element (IM) or the heated object (HO) is transferred to the upper plate (15), and the heat from the upper plate (15) is transferred back to the working coil (WC), which can damage the working coil (WC).

[0081] In this way, the insulating material (35) can prevent the working coil (WC) from being damaged by heat by blocking the heat transferred to the working coil (WC), and furthermore, can prevent the heating performance of the working coil (WC) from deteriorating.

[0082] For reference, although not an essential component, a spacer (not shown) may be installed between the working coil (WC) and the insulation (35).

[0083] Specifically, a spacer (not shown) can be inserted between the working coil (WC) and the insulating material (35) so that the working coil (WC) and the insulating material (35) do not come into direct contact. Accordingly, the spacer (not shown) can block heat generated as the intermediate heating element (IM) or the object to be heated (HO) is heated by the operation of the working coil (WC) from being transferred to the working coil (WC) through the insulating material (35).

[0084] That is, since the spacer (not shown) can partially share the role of the insulation material (35), the thickness of the insulation material (35) can be minimized, and thereby the gap between the object to be heated (HO) and the working coil (WC) can be minimized.

[0085] Additionally, a plurality of spacers (not shown) may be provided, and the plurality of spacers may be spaced apart from each other between the working coil (WC) and the insulation material (35). Accordingly, air sucked into the inside of the case (25) by the cooling fan (55) described later may be guided to the working coil (WC) by the spacers (not shown).

[0086] That is, the spacer (not shown) can improve the cooling efficiency of the working coil (WC) by guiding the air introduced into the case (25) by the cooling fan (55) so that it can be properly delivered to the working coil (WC).

[0087] The shielding plate (45) is mounted below the working coil (WC) to block the magnetic field generated downward when the working coil (WC) is driven. The shielding plate (45) may be ferrite.

[0088] Specifically, the shielding plate (45) can block the magnetic field generated downward when the working coil (WC) is driven, and can be supported upward by the support member (50).

[0089] The support member (50) is installed between the lower surface of the shielding plate (45) and the lower plate of the case (25) to support the shielding plate (45) upward.

[0090] Specifically, the support member (50) can indirectly support the insulation material (35) and the working coil (WC) upward by supporting the shielding plate (45) upward, thereby allowing the insulation material (35) to be in close contact with the upper plate (15).

[0091] As a result, the distance between the working coil (WC) and the object to be heated (HO) can be maintained at a constant level.

[0092] For reference, the support member (50) may include, for example, an elastic body (e.g., a spring) for supporting the shielding plate (45) upward, but is not limited thereto. Also, since the support member (50) is not an essential component, it may be omitted from the cooking device (1).

[0093] A cooling fan (55) can be installed inside the case (25) to cool the working coil (WC).

[0094] Specifically, the cooling fan (55) can be driven by the aforementioned control module and installed on the side wall of the case (25). Of course, the cooling fan (55) may be installed at a location other than the side wall of the case (25), but for convenience of explanation in the embodiment of the present disclosure, the cooling fan (55) is installed on the side wall of the case (25) as an example.

[0095] In addition, as shown in FIGS. 3 and 4, the cooling fan (55) can draw in air from outside the case (25) and transfer it to the working coil (WC), or draw in air (especially heat) from inside the case (25) and discharge it to the outside of the case (25).

[0096] Through this, efficient cooling of the components inside the case (25) (especially the working coil (WC)) is possible.

[0097] In addition, as described above, the air outside the case (25) delivered to the working coil (WC) by the cooling fan (55) can be guided to the working coil (WC) by the spacer. Accordingly, direct and efficient cooling of the working coil (WC) becomes possible, thereby improving the durability of the working coil (WC) (i.e., improving durability by preventing thermal damage).

[0098] The intermediate heating element (IM) may be a material having a resistance value that can be heated by a working coil (WC).

[0099] The thickness of the intermediate heating element (IM) may be inversely proportional to the resistance value (i.e., surface resistance value) of the intermediate heating element (IM). That is, as the thickness of the intermediate heating element (IM) decreases, the resistance value (i.e., surface resistance value) of the intermediate heating element (IM) increases, so the intermediate heating element (IM) can be installed thinly on the upper plate (15) to change its characteristics into a heatable load.

[0100] For reference, the intermediate heating element (IM) according to the embodiment of FIGS. 2 to 3 may have a thickness between, for example, 0.1 μm and 1,000 μm, but is not limited thereto.

[0101] An intermediate heating element (IM) having such characteristics exists to heat a non-magnetic material, and the impedance characteristics between the intermediate heating element (IM) and the object to be heated (HO) can change depending on whether the object to be heated (HO) placed on the upper plate (15) is a magnetic material or a non-magnetic material.

[0102] The case where the object to be heated (HO) is a magnetic material is explained as follows.

[0103] The resistance component (R1) and inductor component (L1) of the object to be heated (HO) form an equivalent circuit with the resistance component (R2) and inductor component (L2) of the intermediate heating body (IM). At this time, the impedance of the magnetic object to be heated (HO) (i.e., the impedance composed of R1 and L1) may be smaller than the impedance of the intermediate heating body (IM) (i.e., the impedance composed of R2 and L2). Accordingly, the magnitude of the eddy current (I1) applied to the magnetic object to be heated (HO) may be greater than the magnitude of the eddy current (I2) applied to the intermediate heating body (IM). Accordingly, most of the eddy current generated by the working coil (WC) is applied to the object to be heated (HO), and the object to be heated (HO) can be heated. That is, when the object to be heated (HO) is a magnetic material, the aforementioned equivalent circuit is formed and most of the eddy current is applied to the object to be heated (HO), so the working coil (WC) can directly heat the object to be heated (HO).

[0104] Next, the case where the object to be heated is a non-magnetic material is explained as follows.

[0105] When a non-magnetic object to be heated (HO) is placed on the upper plate (15) and the working coil (WC) is driven, there is no impedance in the non-magnetic object to be heated (HO), but there may be impedance in the intermediate heating body (IM). That is, a resistance component (R) and an inductor component (L) may exist only in the intermediate heating body (IM). Therefore, when a non-magnetic object to be heated (HO) is placed on the upper plate (15) and the working coil (WC) is driven, the resistance component (R) and the inductor component (L) of the intermediate heating body (IM) may form an equivalent circuit. Accordingly, an eddy current (I) may be applied only to the intermediate heating body (IM), and an eddy current may not be applied to the non-magnetic object to be heated (HO). More specifically, the eddy current (I) generated by the working coil (WC) is applied only to the intermediate heating element (IM), so that the intermediate heating element (IM) can be heated. That is, when the object to be heated (HO) is a non-magnetic material, the eddy current (I) is applied to the intermediate heating element (IM) and the intermediate heating element (IM) is heated, so that the object to be heated (HO), which is not magnetic, can be indirectly heated by the intermediate heating element (IM) heated by the working coil (WC). In this case, the intermediate heating element (IM) can be the main heat source.

[0106] In summary, regardless of whether the object to be heated (HO) is magnetic or non-magnetic, the object to be heated (HO) can be heated directly or indirectly by a single heat source called the working coil (WC). That is, if the object to be heated (HO) is magnetic, the working coil (WC) directly heats the object to be heated (HO), and if the object to be heated (HO) is non-magnetic, an intermediate heating element (IM) heated by the working coil (WC) can indirectly heat the object to be heated (HO).

[0108] Meanwhile, when the object to be heated (HO) is a magnetic material, the heating efficiency is highest when the entire magnetic field generated by the working coil (WC) is coupled with the object to be heated (HO); however, there is a problem in that the heating efficiency decreases somewhat as a portion of the magnetic field is coupled with the intermediate heating element (IM). Therefore, a method is required to control the coupling force between the magnetic field generated by the working coil (WC) and the intermediate heating element (IM) to be weak when the object to be heated (HO) is a magnetic material, and to control the coupling force between the magnetic field generated by the working coil (WC) and the intermediate heating element (IM) to be strong when the object to be heated (HO) is a non-magnetic material.

[0109] Accordingly, the cooktop according to the embodiment of the present disclosure includes a plurality of working coils (WC), and by selectively driving the plurality of working coils (WC), the coupling force between the magnetic field generated in the working coils (WC) and the intermediate heating element (IM) is to be controlled. In other words, the cooktop according to the embodiment of the present disclosure includes a plurality of working coils (WC), and by selectively driving the plurality of working coils (WC), the amount of heat generated by the intermediate heating element (IM) is to be controlled.

[0110] To this end, an intermediate heating element (IM) may be arranged to overlap vertically with at least two of the plurality of working coils (WC), and various embodiments according to this are described with reference to FIGS. 5 to 8.

[0111] FIG. 5 is a drawing showing an intermediate heating element and a plurality of working coils according to a first embodiment of the present disclosure.

[0112] According to the first embodiment of the present disclosure, the cooktop (1) may include two working coils (WC1) (WC2). That is, the plurality of working coils (WC) may include a first and second working coil (WC1) (WC2).

[0113] Each of the first and second working coils (WC1) (WC2) may be arranged such that at least a portion overlaps the intermediate heating element (IM) in a vertical direction. Referring to the example in FIG. 5, the intermediate heating element (IM) may be a circular shape with a hole in the center. However, this is merely exemplary, and the intermediate heating element (IM) may be a square, elliptical shape, etc. with a hole in the center.

[0114] Each of the first and second working coils (WC1) (WC2) may also be wound in a shape such as a circle or an ellipse with a hole in the center. However, this is merely an example, and each of the first and second working coils (WC1) (WC2) may also be in a square shape with a hole in the center. The first and second working coils (WC1) (WC2) may be arranged side by side.

[0115] Each of the first and second working coils (WC1) (WC2) may have a portion that overlaps vertically with the intermediate heating element (IM), and the remainder may not overlap vertically with the intermediate heating element (IM). For example, at least a portion of each of the first and second working coils (WC1) (WC2) may be located below a hole formed in the intermediate heating element (IM).

[0116] FIG. 5 is a top view of a plurality of working coils (WC1) (WC2) and an intermediate heating element (IM) placed thereon, wherein the portion of the first and second working coils (WC1) (WC2) that overlaps vertically with the intermediate heating element (IM) is shown as a dotted line, and the portion that does not overlap vertically with the intermediate heating element (IM) is shown as a solid line.

[0117] That is, according to the first embodiment, all of the plurality of working coils (WC1) (WC2) may include at least a portion that overlaps vertically with the intermediate heating element (IM).

[0118] According to the first embodiment, the number of working coils (WC) is small, which has the advantage of reducing costs and simplifying the structure.

[0119] FIG. 6 is a drawing showing an intermediate heating element and a plurality of working coils according to a second embodiment of the present disclosure.

[0120] According to a second embodiment of the present disclosure, the cooktop (1) includes a plurality of working coils (WC), and an intermediate heating element (IM) may be arranged to overlap vertically with some of the plurality of working coils (WC).

[0121] Referring to the example in FIG. 6, the intermediate heating element (IM) may have a square shape with a hole in the center. However, this is merely an example, and the intermediate heating element (IM) may have a shape such as a circle or an ellipse with a hole in the center.

[0122] Each of the multiple working coils (WC) may also be wound in a square shape with a hole in the center. However, this is merely an example, and each of the multiple working coils (WC) may also be wound in a circular or elliptical shape with a hole in the center.

[0123] According to the example of FIG. 6, a plurality of working coils (WC) may include first to twelfth working coils (WC1 to WC12).

[0124] Each of the multiple working coils (WC) may have a different size. For example, as shown in FIG. 6, the first to ten working coils (WC1 to WC10) may have a first size, and the eleventh to twelfth working coils (WC11) (WC12) may have a second size smaller than the first size. However, this is merely illustrative, and the size of each of the first to twelfth working coils (WC1 to WC12) may vary.

[0125] An intermediate heating element (IM) may be arranged to overlap vertically with some of the multiple working coils (WC). If multiple heating zones are pre-designated on the top plate (15), the intermediate heating element (IM) may be installed at a position corresponding to at least one of the multiple heating zones. A heating zone may refer to an area where a heated object (HO) can be heated.

[0126] For example, in the example of FIG. 6, the top plate (15) may have first to fourth heating zones pre-designated. For example, the first heating zone may be an area where the object to be heated (HO) can be heated by the first to second working coils (WC1 to WC2), the second heating zone may be an area where the object to be heated (HO) can be heated by the third to sixth working coils (WC3 to WC6), the third heating zone may be an area where the object to be heated (HO) can be heated by the seventh to tenth working coils (WC7 to WC10), and the fourth heating zone may be an area where the object to be heated (HO) can be heated by the eleventh to twelfth working coils (WC11 to WC12).

[0127] According to the example of FIG. 6, the intermediate heating element (IM) can be installed at a position corresponding to the first heating zone. That is, the intermediate heating element (IM) can be positioned so as to overlap vertically with the first and second working coils (WC1) (WC2) among the plurality of working coils (WC), and not to overlap vertically with the remaining working coils.

[0128] Additionally, each of the first and second working coils (WC1) (WC2) can be arranged such that a portion overlaps the intermediate heating element (IM) in the vertical direction, and the remainder overlaps the hole formed in the intermediate heating element (IM) in the vertical direction. FIG. 6 is a top view of a plurality of working coils (WC1 to WC12) and an intermediate heating element (IM) placed thereon, wherein the portion of the first and second working coils (WC1) (WC2) that overlaps the intermediate heating element (IM) in the vertical direction is shown as a dotted line, and the portion that does not overlap the intermediate heating element (IM) in the vertical direction is shown as a solid line.

[0129] That is, according to the second embodiment, a portion of a plurality of working coils (WC1 to WC12), for example, a working coil corresponding to the first heating zone, may include a portion that overlaps vertically with the intermediate heating body (IM).

[0130] According to the second embodiment, the cooktop (1) is equipped with a heating zone dedicated to magnetic containers (second to fourth heating zones) capable of heating only magnetic containers, and a combined heating zone (first heating zone) capable of heating both magnetic containers and non-magnetic containers, thereby having the advantage of maximizing heating efficiency in each heating zone.

[0131] FIG. 7 is a drawing showing an intermediate heating element and a plurality of working coils according to a third embodiment of the present disclosure.

[0132] According to the third embodiment of the present disclosure, the cooktop (1) includes a plurality of working coils (WC), and an intermediate heating element (IM) may be arranged to overlap vertically with some of the plurality of working coils (WC).

[0133] Referring to the example in FIG. 7, the intermediate heating element (IM) may be a hexagonal shape with a hole in the center. However, this is merely an example, and the intermediate heating element (IM) may be a shape such as a circle, ellipse, or square with a hole in the center.

[0134] Each of the multiple working coils (WC) may also be wound in a circular shape with a hole in the center. However, this is merely an example, and each of the multiple working coils (WC) may also be wound in a circular, elliptical, or square shape with a hole in the center.

[0135] According to the example of FIG. 7, the plurality of working coils (WC) may include 48 small working coils. However, since the number of working coils (WC) is merely exemplary, it is reasonable to assume that it is not limited thereto.

[0136] Each of the multiple working coils (WC) may have the same size. Unlike the example in FIG. 7, the sizes of each of the multiple working coils (WC) may be different.

[0137] Among the plurality of working coils (WC) shown in FIG. 7, the working coils that overlap vertically with or are adjacent to the left half of the intermediate heating element (IM) may be classified as the first working coil (WC1), and the working coils that overlap vertically with or are adjacent to the right half of the intermediate heating element (IM) may be classified as the second working coil (WC2). This classification is made to explain the operation method of the working coil (WC) when a heated object (HO) is located at a position corresponding to the intermediate heating element (IM), and this will be explained in FIG. 9 to FIG. 11.

[0138] As shown in the example of FIG. 7, when a plurality of small working coils (WC) of a size smaller than a predetermined size are arranged, a heating zone may not be pre-designated on the top plate (15). In this way, the cooktop (1) without a designated heating zone detects the position where an object to be heated (HO) is placed on the top plate (15), and a working coil arranged at a position that overlaps vertically with the detected position of the object to be heated (HO) can be operated.

[0139] An intermediate heating element (IM) may be positioned to overlap vertically with some of the multiple working coils (WC). As shown in the example of FIG. 7, the intermediate heating element (IM) may be installed at a position corresponding to the center of the multiple working coils (WC). However, this is merely exemplary, and the intermediate heating element (IM) may also be installed at a position where at least some of it overlaps vertically with the working coil (WC) positioned closest to the top plate (15). That is, in a cooktop (1) where the heating zone is not designated, the intermediate heating element (IM) may be installed at various positions. The intermediate heating element (IM) may be installed at a position where the object to be heated (HO) is frequently placed to increase user convenience for users who frequently use non-magnetic containers, or installed at a position where the object to be heated (HO) is not frequently placed to increase user convenience for users who frequently use magnetic containers.

[0140] According to the third embodiment, since the object to be heated (HO) can be heated at any location regardless of its position and size, there is an advantage in that the freedom of the container is improved.

[0141] FIG. 8 is a drawing showing an intermediate heating element and a plurality of working coils according to a fourth embodiment of the present disclosure.

[0142] According to the third embodiment of the present disclosure, the cooktop (1) includes a plurality of working coils (WC) and may include a plurality of intermediate heating elements (IM) that overlap vertically with some of the plurality of working coils (WC).

[0143] Referring to the example in Fig. 8, the intermediate heating element (IM) may be a square shape with a hole in the center, but this is merely an example and may be various shapes such as a circle, ellipse, or hexagon.

[0144] Each of the multiple working coils (WC) may be an elliptical shape with a hole in the center, but this is merely an example and may be various shapes such as a circle, square, or hexagon.

[0145] According to the example of FIG. 8, a plurality of working coils (WC) may include four working coils located on the left and four working coils located on the right. In this case, a heating zone may be formed with a first heating zone heated by the four working coils located on the left and a second heating zone heated by the four working coils located on the right.

[0146] Meanwhile, the intermediate heating element (IM) may include a first intermediate heating element (IM1) positioned at a location corresponding to the first heating zone and a second intermediate heating element (IM2) positioned at a location corresponding to the second heating zone.

[0147] Meanwhile, among the plurality of working coils (WC) shown in FIG. 8, for each of the first intermediate heating element (IM1) and the second intermediate heating element (IM2), the working coil adjacent to the upper part may be designated as the first working coil (WC1), and the working coil adjacent to the lower part may be designated as the second working coil (WC2). This is merely a distinction made to explain the operation method of the working coil (WC) when a heated object (HO) is located at a position corresponding to the intermediate heating element (IM), and this will be explained in FIG. 9 to FIG. 11.

[0148] According to the fourth embodiment, there is an advantage that both magnetic and non-magnetic containers can be heated in all heating zones.

[0149] As described above, according to various embodiments of the present disclosure, a cooktop (1) comprises a plurality of working coils (WC) and at least one intermediate heating element (IM), and the intermediate heating element (IM) may be arranged to overlap in a vertical direction with at least two of the plurality of working coils (WC). Furthermore, the cooktop (1) can improve heating efficiency for a magnetic container by controlling the amount of heat generated by the intermediate heating element (IM) by alternately operating the plurality of working coils (WC).

[0150] Specifically, when a heated object (HO) is placed in a position that overlaps vertically with an intermediate heating element (IM), the working coils located adjacent to the intermediate heating element (IM) can be divided into a first working coil and a second working coil and operated alternately. At this time, the first working coil and the second working coil may include working coils corresponding to each divided area when the intermediate heating element (IM) is divided in half (left / right or upper / lower).

[0151] FIG. 9 is a drawing showing the output when the working coils of a cooktop according to an embodiment of the present disclosure operate simultaneously, FIG. 10 is a drawing showing the output when the working coils of a cooktop according to an embodiment of the present disclosure operate alternately in a first manner, and FIG. 11 is a drawing showing the output when the working coils of a cooktop according to an embodiment of the present disclosure operate alternately in a second manner.

[0152] FIGS. 9 to 11 illustrate the output of a first working coil (WC1) and the output of a second working coil (WC2) when an intermediate heating element and a plurality of working coils are arranged according to the first embodiment described in FIG. 5. That is, in FIGS. 9 to 11, (a) represents the output of the first working coil (WC1) and (b) represents the output of the second working coil (WC2).

[0153] However, this description is provided only for the first embodiment for the sake of convenience of explanation, and the output may appear similarly in the second to fourth embodiments. That is, when an intermediate heating element and a plurality of working coils are arranged according to the second to fourth embodiments described in each of FIGS. 6 to 8, (a) of FIGS. 9 to 11 may represent the output of the first working coil (WC1), and (b) may represent the output of the second working coil (WC2).

[0154] Also, in FIGS. 9 to 11, the output of the first and second working coils (WC1) (WC2) may be the maximum output of each of the first and second working coils (WC1) (WC2). That is, FIGS. 9 to 11 may be the output of each of the first and second working coils (WC1) (WC2) when the input voltage of the inverter unit (140) is constant and the current that outputs maximum power to the working coil (WC) is applied at an operating frequency.

[0155] First, referring to FIG. 9, the first working coil (WC1) and the second working coil (WC2) can operate simultaneously for one cycle, and in this case, each of the first and second working coils (WC1) (WC2) can continuously output maximum power (Pmax) for one cycle. When the first and second working coils (WC1) (WC2) operate simultaneously, a closed loop can be formed over the entire area of ​​the intermediate heating element (IM), that is, since the closed loop is formed at a maximum size, the magnetic field coupling force of the intermediate heating element (IM) is increased, and the amount of heat generated can be maximum.

[0156] Accordingly, since the heating efficiency for a magnetic object to be heated (HO) may be reduced, according to various embodiments of the present disclosure, the magnetic field coupling force of an intermediate heating body (IM) is to be weakened by the alternating operation of the first and second working coils (WC1) (WC2). That is, according to various embodiments of the present disclosure, an intermediate heating body (IM) may alternately operate the first working coil (WC1) adjacent to the left (or upper) side and the second working coil (WC2) adjacent to the right (or lower) side.

[0157] First, referring to FIG. 10, the first working coil (WC1) and the second working coil (WC2) may not operate in at least some sections of a cycle. Specifically, if a cycle is divided into a first section (t1) and a second section (t2), the first working coil (WC1) may operate only in the first section (t1) and not in the second section (t2), and the second working coil (WC2) may operate only in the second section (t2) and not in the first section (t1).

[0158] Accordingly, in the first section (t1), a closed loop is formed only in the left (or upper) region of the intermediate heating element (IM), and thus the magnetic field coupling force may be reduced compared to when a closed loop is formed in the entire region of the intermediate heating element (IM). Similarly, in the second section (t2), a closed loop is formed only in the right (or lower) region of the intermediate heating element (IM), and thus the magnetic field coupling force may be reduced compared to when a closed loop is formed in the entire region of the intermediate heating element (IM).

[0159] Next, referring to FIG. 11, the first working coil (WC1) and the second working coil (WC2) may not operate in at least some sections of a cycle. Specifically, if a cycle is divided into a first section (t1), a second section (t2), and a third section (t3), the first working coil (WC1) may operate only in the first and second sections (t1)(t2) and not in the third section (t3), and the second working coil (WC2) may operate only in the second and third sections (t2)(t3) and not in the first section (t1).

[0160] Accordingly, in the first section (t1), a closed loop is formed only in the left (or upper) region of the intermediate heating element (IM), and thus the magnetic field coupling force may be reduced compared to when a closed loop is formed in the entire region of the intermediate heating element (IM). In the second section (t2), a closed loop is formed in the entire region of the intermediate heating element (IM), so the magnetic field coupling force of the intermediate heating element (IM) may be strengthened compared to the first section (t1) and the third section (t2). Again, in the third section (t3), a closed loop is formed only in the right (or lower) region of the intermediate heating element (IM), and thus the magnetic field coupling force may be weakened compared to when a closed loop is formed in the entire region of the intermediate heating element (IM).

[0161] Meanwhile, although the operation cycle of the inverter unit (140) is described as being divided into two sections in FIG. 10 and into three sections in FIG. 11, this is merely illustrative and the operation cycle can be divided into two or more sections.

[0162] That is, the operation cycle of the inverter unit (140) is divided into two or more sections, and at least one of the multiple working coils (WC) may not operate in at least one section. In this way, if at least one of the multiple working coils (WC) does not operate in at least one section, the area of ​​the closed loop formed in the intermediate heating body (IM) is narrowed, and accordingly, the magnetic field coupling force of the intermediate heating body (IM) is weakened, thereby increasing the magnetic field coupled with the object to be heated (HO) and improving heating efficiency.

[0163] Meanwhile, when heating a magnetic object to be heated (HO), heating efficiency can be improved by not operating at least one of the plurality of working coils (WC) in at least a portion of the section as described above, but when heating a non-magnetic object to be heated (HO), heating efficiency can be maximized only when all of the plurality of working coils (WC) operate.

[0164] Accordingly, the cooktop (1) according to an embodiment of the present disclosure can operate in different heating modes depending on the type of object to be heated (HO). Next, with reference to FIG. 12, a method of the cooktop (1) according to an embodiment of the present disclosure operating in different heating modes depending on the object to be heated (HO) will be explained.

[0165] FIG. 12 is a control block diagram for explaining the operation method of a cooktop according to an embodiment of the present disclosure.

[0166] The cooktop (1) may include an inverter unit (140), a controller (170), and a container detection unit (180). FIG. 12 illustrates only some configurations to explain the operation method of the cooktop, and the cooktop (1) may include additional configurations other than those shown in FIG. 12.

[0167] The inverter unit (140) can be driven to supply current to the working coil (WC).

[0168] The controller (170) can control the operation of the cooktop (1). The controller (170) can control the inverter unit (140) and the container detection unit (180), respectively.

[0169] The container detection unit (180) can detect the object to be heated (HO). The container detection unit (180) can detect the type or size of the object to be heated (HO). The type of the object to be heated (HO) may include the material of the object to be heated (HO). The type of the object to be heated (HO) may be magnetic or non-magnetic (including non-metallic).

[0170] The container detection unit (180) may be equipped with at least one sensor (not shown) for detecting the type or size of the container.

[0171] According to one embodiment, the container detection unit (180) can detect the type or size of the object to be heated (HO) by receiving a user input selecting at least one of the type or size of the object to be heated (HO). In this case, the container detection unit (180) may include an input interface (not shown) for receiving the user input.

[0172] According to another embodiment, the container detection unit (180) can detect the type or size of the object to be heated (HO) according to a stored container detection algorithm. For example, the container detection unit (180) can detect the type or size of the object to be heated (HO) based on at least one data, such as the magnitude of the current flowing through the working coil (WC) or the magnitude of the output, for a predetermined time after the heating mode is initiated.

[0173] That is, there are various ways in which the container detection unit (180) detects the object to be heated (HO), and the present disclosure is not limited thereto.

[0174] The controller (170) may operate in a first heating mode or a second heating mode depending on the type of object to be heated (HO). The first heating mode is an operating mode for heating a magnetic container, and the second heating mode may be an operating mode for heating a non-magnetic container.

[0175] The controller (170) can control the inverter unit (140) to operate in a first heating mode when the object to be heated (HO) is a magnetic material, and to operate in a second heating mode when the object to be heated (HO) is a non-magnetic material.

[0176] The controller (170) can control the inverter unit (140) so that at least one of the plurality of working coils (WC) does not operate during at least a portion of one cycle when operating in the first heating mode, and can control the inverter unit (140) so that all of the plurality of working coils (WC) operate during one cycle when operating in the second heating mode.

[0177] According to the first embodiment, when operating in the first heating mode, the controller (170) can alternately operate the working coil (WC) in the first manner described in FIG. 10. Specifically, the controller (170) can control the inverter unit (140) so that for half of a cycle, only the first working coil (WC1) operates, and for the remaining half, only the second working coil (WC2) operates.

[0178] According to the second embodiment, when operating in the first heating mode, the controller (170) can alternately operate the working coil (WC) in the second manner described in FIG. 11. Specifically, the operation cycle of the inverter unit (140) may include a section where only the first working coil (WC1) operates, a section where only the second working coil (WC2) operates, and a section where the first working coil (WC1) and the second working coil (WC2) operate together. The controller (170) can control the inverter unit (140) so that only the first working coil (WC1) operates during the first section (t1) of one cycle, the first working coil (WC1) and the second working coil (WC2) operate together during the second section (t2) after the first section (t1), and only the second working coil (WC2) operates during the third section (t3) after the second section (t2). Meanwhile, the order of the first to third sections (t1 to t3) may be changed according to the embodiment. That is, when the first section (t1) is a section where only the first working coil (WC1) operates, the second section (t2) is a section where the first working coil (WC1) and the second working coil (WC2) operate together, and the third section (t3) is a section where only the second working coil (WC2) operates, the order of operation may be changed, such as by operating in the order of the first section (t1), the third section (t3), and the second section (t2), or by operating in the order of the second section (t2), the third section (t3), and the first section (t1).

[0179] The time corresponding to each of the first to third intervals (t1 to t3) may be the same. That is, each interval distinguished in one period may be equal.

[0180] The controller (170) can adjust the operating frequency of the inverter unit (140) so that each of the plurality of working coils (WC) produces a maximum output (Pmax) when operating in the first heating mode and the second heating mode, respectively. The maximum output (Pmax) may refer to the maximum power that can be output by a single working coil. When a single coil operates at the maximum output (Pmax), it may have a period of 120Hz, which is twice the commercial power supply.

[0181] Hereinafter, the output of the working coil is described when a plurality of working coils (WC) and an intermediate heating element (IM) are configured as shown in FIG. 5.

[0182] In the first heating mode, each working coil operates to produce maximum output, so the output during one cycle may be greater than or equal to the maximum output (Pmax). In the first embodiment, the output is the maximum output (Pmax) in the first section (t1) and the output is the maximum output (Pmax) in the second section (t2), so the output per coil during one cycle (T) is 1 / 2 * maximum output (1 / 2 * Pmax) and the total output may be the maximum output (Pmax). In the second embodiment, the output is the maximum output (Pmax) in the first section (t1), the output is 2 * maximum output (2 * Pmax) in the second section (t2), and the output is the maximum output (Pmax) in the third section (t3), so the output per coil during one cycle (T) is 2 / 3 * maximum output (2 / 3 * Pmax) and the total output may be 4 / 3 * maximum output (4 / 3 * Pmax).

[0183] That is, in the first heating mode, although there is a period where not all of the multiple working coils (WC) operate simultaneously, the maximum output (Pmax) can be guaranteed.

[0184] Meanwhile, in the second heating mode, all working coils operate to produce maximum output, so the output per coil during one cycle (T) is maximum output (Pmax), and the total output can be 2*max output (2*Pmax).

[0185] According to various embodiments of the present disclosure, the cooktop (1) can heat all objects to be heated (HO) regardless of the material, and also has the advantage of improving heating efficiency and increasing output performance by suppressing the heat output of the intermediate heating element (IM) when heating magnetic materials and maximizing the heat output of the intermediate heating element (IM) when heating non-magnetic materials through the configuration and control of a plurality of working coils (WC). In addition, since the working coils operate in the same phase while only alternating control of the plurality of working coils (WC), separate phase control is unnecessary, which has the advantage of simplifying the control logic.

[0187] The above description is merely an illustrative explanation of the technical concept of the present disclosure, and those skilled in the art to which the present disclosure pertains may make various modifications and variations within the scope of the essential characteristics of the present disclosure without departing from its nature.

[0188] Accordingly, the embodiments disclosed in this disclosure are intended to explain, not limit, the technical concept of this disclosure, and the scope of the technical concept of this disclosure is not limited by these embodiments.

[0189] The scope of protection of the present disclosure shall be interpreted by the claims below, and all technical ideas within the equivalent scope shall be interpreted as being included within the scope of rights of the present disclosure.

Claims

Claim 1 A cooking apparatus comprising: a top plate portion on which an object to be heated is placed; an intermediate heating element disposed on the top plate portion; a plurality of working coils that generate a magnetic field coupled to at least one of the object to be heated and the intermediate heating element; an inverter portion that applies current to the plurality of working coils; and a controller that operates in a first heating mode in which at least one of the plurality of working coils does not operate during at least a portion of a cycle when the object to be heated is a magnetic material, and operates in a second heating mode in which all of the plurality of working coils operate during the cycle when the object to be heated is a non-magnetic material. Claim 2 A cooking appliance according to claim 1, wherein the plurality of working coils includes at least a first and a second working coil, and the controller controls the inverter unit such that, when operating in the first heating mode, only the first working coil operates for half of the cycle and only the second working coil operates for the remaining half. Claim 3 A cooking apparatus according to claim 1, wherein the plurality of working coils includes at least a first and a second working coil, and when operating in the first heating mode, the cycle includes a section in which only the first working coil operates, a section in which only the second working coil operates, and a section in which the first working coil and the second working coil operate together. Claim 4 A cooking device according to claim 3, wherein the controller controls the inverter unit such that only the first working coil operates during a first section of the cycle, the first working coil and the second working coil operate together during a second section after the first section, and only the second working coil operates during a third section after the second section. Claim 5 In claim 4, the time corresponding to each of the first to third intervals is the same cooking device. Claim 6 A cooking device according to claim 1, wherein the controller adjusts the operating frequency of the inverter unit so that the plurality of working coils produce a maximum output when operating in the first heating mode. Claim 7 delete Claim 8 delete Claim 9 delete Claim 10 A cooking device according to claim 1, wherein the intermediate heating element is arranged to overlap vertically with at least two of the plurality of working coils. Claim 11 A cooking device according to claim 1, wherein the intermediate heating element is arranged to overlap vertically with some of the plurality of working coils. Claim 12 A cooking device according to claim 11, wherein, when a plurality of heating zones are pre-designated in the upper plate portion, the intermediate heating element is installed at a position corresponding to any one of the plurality of heating zones. Claim 13 A cooking device according to claim 11, wherein, when a heating zone is not pre-designated in the upper plate portion, the intermediate heating element is installed at a position corresponding to the center of the plurality of working coils. Claim 14 A cooking appliance according to claim 11, wherein, when a heating zone is not pre-designated in the upper plate portion, the intermediate heating element is installed in a position where at least a portion overlaps vertically with a working coil positioned closest to the apex of the upper plate portion.

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