Induction heating cooker

Abstract

To provide an induction heating cooker capable of efficiently heating a heating target object by a plurality of heating coils.SOLUTION: An induction heating cooker includes a top plate, a coil unit, and a control unit for controlling heating of a heating target object by the coil unit. The coil unit has a plurality of coil pieces arranged in a heating area in a plan view, and the heating area includes a first heating area and a second heating area. The heating area has a plurality of coil arrangement areas defined in a plan view by respective outer periphery lines for defining the outer periphery of each of the first heating area and the second heating area, and a plurality of boundary lines that extend radially from the center of each of the first heating area and the second heating area toward the outer periphery. The plurality of coil pieces are arranged within a plurality of coil arrangement areas in a plan view, and the control unit controls heating of the heating target object while passing a current through all of the plurality of coil pieces.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an induction heating cooker. [Background technology]

[0002] Conventionally, induction heating cookers have been known that have multiple heating coils and allow a cooking vessel to be placed across the multiple heating coils. For example, Patent Document 1 discloses an induction heating cooker that, when it detects that a load is placed on a top plate, drives a relay and passes a high-frequency current through the heating coil on which the load is placed, out of the multiple heating coils, to heat the load. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-141082 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, induction heating cookers are required to efficiently heat an object to be heated by using a plurality of heating coils.

[0005] An object of the present disclosure is to provide an induction heating cooker capable of efficiently heating an object to be heated using multiple heating coils. [Means for solving the problem]

[0006] An induction heating cooker according to one embodiment of the present disclosure comprises a top plate, a coil unit arranged below the top plate, and a control unit that controls heating of an object to be heated by the coil unit, the coil unit having a plurality of coil pieces arranged in a heating area that heats the object to be heated in a planar view, the heating area including a first heating area and a second heating area partially overlapping with the first heating area, the heating area having a plurality of coil arrangement areas defined in a planar view by respective outer periphery lines that define the outer periphery of each of the first heating area and the second heating area, and a plurality of boundary lines that extend radially from the center of each of the first heating area and the second heating area toward the outer periphery, the plurality of coil pieces being arranged within the plurality of coil arrangement areas in a planar view, and the control unit controlling heating of the object to be heated while passing current through all of the plurality of coil pieces. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide an induction heating cooker that can efficiently heat an object to be heated by using a plurality of heating coils. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic perspective view of an example of an induction heating cooker according to an embodiment of the present disclosure; FIG. [Diagram 2] FIG. 2 is a plan view of an example of a coil unit according to an embodiment of the present disclosure; [Diagram 3] A schematic enlarged view of the coil pieces that make up the coil unit in FIG. 2. [Figure 4] FIG. 1 is a block diagram showing schematic electrical connections relating to a coil unit of an induction heating cooker according to an embodiment of the present disclosure; [Diagram 5] FIG. 1 is a schematic circuit diagram showing an example of electrical connections of an induction heating cooker according to an embodiment of the present disclosure. [Figure 6] A graph showing an example of a current waveform when the phase difference between currents flowing through adjacent portions of two adjacent coil pieces is 0°. [Figure 7]A graph showing an example of a current waveform when the phase difference between currents flowing through adjacent portions of two adjacent coil pieces is 180°. [Figure 8] FIG. 1 is a schematic diagram showing an example of a heating region controlled in a first heating mode in an induction heating cooker according to an embodiment of the present disclosure. [Figure 9] 1 is a diagram showing an example of a temperature distribution of an object to be heated when the object is heated in the first heating mode; [Figure 10] FIG. 1 is a schematic diagram showing an example of a heating region controlled in a second heating mode in an induction heating cooker according to an embodiment of the present disclosure. [Figure 11] 13 is a diagram showing an example of the temperature distribution of an object to be heated when the object is heated in the second heating mode. [Figure 12] 13 is a diagram showing an example of the temperature distribution of an object to be heated when the object is heated in the third heating mode. [Figure 13] 13 is a diagram showing an example of the temperature distribution of an object to be heated when the object is heated in the fourth heating mode. [Figure 14A] Graph showing an example of temperature change of an object to be heated when the object is heated by an induction heating cooker having a conventional heating coil. [Figure 14B] 1 is a graph showing an example of a temperature change of an object to be heated when the object is heated by an induction heating cooker according to an embodiment of the present invention. [Figure 15] FIG. 11 is a plan view of an example of a coil unit of an induction heating cooker according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. However, the configuration described below is merely an example of the present disclosure, and the present disclosure is not limited to the following embodiment. The technology in the present disclosure is not limited to this, and various modifications, substitutions, additions, omissions, etc. are possible depending on the design, etc., even if it is other than these embodiments, as long as it does not deviate from the technical idea of ​​the present disclosure.

[0010] Although the present disclosure has been fully described in connection with the preferred embodiments with reference to the accompanying drawings, various changes and modifications will be apparent to those skilled in the art, and such changes and modifications should be understood to be included within the scope of the present disclosure as defined by the appended claims unless they depart therefrom.

[0011] Conventionally, induction heating cookers having multiple heating coils have a heating area, and multiple heating coils are arranged in the heating area. In this case, the conventional induction heating cooker controls the heating in the heating area by switching whether or not to pass a high-frequency current to the heating coils, for example, by turning on / off a relay. Conventional induction heating cookers change the strength of the heating in the heating area locally, for example, by stopping the current to some of the heating coils, or change the overall heat power in the heating area.

[0012] Thus, in the conventional induction heating cooker, since there is a heating coil that is not energized by the heating control, it is difficult to heat at high power. In addition, in the conventional induction heating cooker, the strength of heating in the heating area is changed locally depending on whether or not the heating coil is energized, so there are few modes of local change. Furthermore, since the strength of heating in the heating area is switched depending on whether or not the heating coil is energized, the conventional induction heating cooker has a low response speed of heating control. In addition, since the conventional induction heating cooker cannot detect the magnetic coupling between the heating coil that is not energized and the object to be heated, the reaction of the object to be heated cannot be reflected in the heating control. In addition, in the conventional induction heating cooker, the local strength of heating cannot be controlled in the area heated by one heating coil. In addition, in the conventional induction heating cooker, the part of the object to be heated that is placed above the gap between the heating coils cannot be heated.

[0013] Furthermore, with conventional induction heating cookers, when multiple heating coils are used to heat a single load, there is a problem that the multiple heating coils may interfere with each other, resulting in reduced thermal efficiency, poor heating temperature distribution, and the generation of humming noise.

[0014] The induction heating cooker according to the present disclosure has a plurality of coil pieces for heating one load. The induction heating cooker according to the present disclosure controls heating of the load while passing current through all of the plurality of heating coils (i.e., coil pieces). Therefore, the induction heating cooker according to the present disclosure passes current through all of the coil pieces, so that it is possible to avoid current concentration in one of the plurality of coil pieces, and it is possible to heat the load with high output overall. In addition, since all of the coil pieces are constantly passed current, the response speed is fast. Therefore, each coil piece can respond quickly to an instruction from the controller of the cooking device.

[0015] Moreover, the induction heating cooker can locally control the strength of heating for a load placed on the coil unit by controlling at least a portion of the parameters of the current flowing through each of the multiple coil pieces. Therefore, the induction heating cooker can efficiently heat the load. Furthermore, by controlling the parameters of the current, the induction heating cooker can suppress a decrease in thermal efficiency, a deterioration in the heating temperature distribution, and the generation of a humming noise even if a current flows through multiple coil pieces. Therefore, the induction heating cooker according to the present disclosure can efficiently heat an object to be heated by the multiple coil pieces.

[0016] (Embodiment) [composition] FIG. 1 shows a schematic perspective view of an example of an induction heating cooker 1 according to an embodiment of the present disclosure. Note that the XYZ coordinate system shown in the figure is described to facilitate understanding of the invention and is not intended to limit the invention. The X-axis direction indicates the left-right direction. The Y-axis direction indicates the depth direction. The Z-axis direction indicates the vertical direction.

[0017] As shown in Fig. 1, the induction heating cooker 1 is a cooker that inductively heats a cooking container C that contains an object to be cooked T. The cooking container C is described as an example of an object to be inductively heated by the induction heating cooker 1. The object to be heated is not limited to the cooking container C, and may be any object that can be inductively heated.

[0018] The induction heating cooker 1 has a top plate 2 made of, for example, heat-resistant glass on which a cooking container C is placed, and a housing 3 attached to the bottom surface of the top plate 2. A plurality of coil units 4, 5, a controller 6, and an operation panel 7 are mounted inside the housing 3. The top plate 2 is disposed above the plurality of coil units 4, 5. Each of the plurality of coil units 4, 5 is disposed below the top plate 2, and induction heats the cooking container C placed on the opposing portion of the top plate 2. That is, each of the plurality of coil units 4, 5 functions as an induction heating coil unit.

[0019] Coil unit 4 will be described later. Coil unit 5 is a coil unit different from coil unit 4. Coil unit 5 may be composed of one coil, or may be composed of multiple coils.

[0020] The controller 6 is, for example, a computer, and includes an arithmetic circuit and a storage device. The controller 6 can control the multiple coil units 4 and 5. The controller 6 is an example of a control unit of the induction heating cooker 1 according to the present disclosure.

[0021] The arithmetic circuit controls the overall operation of the induction heating cooker 1. The arithmetic circuit may be either a circuit in which hardware resources and software work together to realize a predetermined function, or a circuit in which a dedicated hardware circuit is used to realize a predetermined function.

[0022] As an example of the former, the arithmetic circuit includes a general-purpose processor such as a CPU or MPU that executes a program to realize a predetermined process or function. The arithmetic circuit is configured to be able to communicate with a storage device. The arithmetic circuit reads out and executes an arithmetic program or the like stored in the storage device to realize various functions in the controller 6. As an example of the latter, the arithmetic circuit includes an FPGA or an ASIC. As can be understood from the above, the arithmetic circuit can be realized using a semiconductor integrated circuit such as a CPU, an MPU, a GPU, an FPGA, a DSP, or an ASIC.

[0023] The storage device is a storage medium that can store various information. The information includes programs and data. For example, the storage device stores an arithmetic program for implementing various functions according to the present embodiment. The storage device is implemented, for example, by a volatile or non-volatile semiconductor memory such as a DRAM, an SRAM, or a flash memory, an SSD, an HDD, or other storage devices, or an appropriate combination thereof. For example, the arithmetic circuit can execute a plurality of heating modes, which will be described later, using the programs or data stored in the storage device.

[0024] The operation panel 7 is electrically connected to the controller 6. The operation panel 7 is an example of an input / output interface device. A user can operate the operation panel 7 to operate the multiple coil units 4, 5 via the controller 6. In addition, the user can grasp the operating status of each of the coil units 4, 5 based on the information displayed on the operation panel 7.

[0025] [Coil unit] The coil unit 4 will be described below with reference to FIGS.

[0026] Fig. 2 is a plan view of an example of a coil unit 4 according to an embodiment of the present disclosure, and Fig. 3 is a schematic enlarged view of a coil piece 10A constituting the coil unit 4 of Fig. 2.

[0027] As shown in FIG. 2, the coil unit 4 includes a plurality of coil pieces 10A to 10J.

[0028] As shown in FIG. 2, in plan view, a first heating region S1, a second heating region S2, and a third heating region S3 are defined. In the first heating region S1, a plurality of coil pieces 10A-10F are arranged. In the second heating region S2, a plurality of coil pieces 10E-10J are arranged. In the third heating region S3, a plurality of coil pieces 10A-10J are arranged. In plan view, the plurality of coil pieces 10G-10J are arranged on the back side in the depth direction (Y-axis direction) of the plurality of coil pieces 10A-10F. In this specification, "plan view" means a view from the vertical direction, i.e., the Z-axis direction. Hereinafter, when there is no need to distinguish between the plurality of coil pieces 10A-10J, they will be collectively referred to as a coil piece 10 or a plurality of coil pieces 10.

[0029] The first heating area S1 is an area having a center C1 in a plan view, and is an area in which the multiple coil pieces 10A-10F are arranged. In the present embodiment, the first heating area S1 has a circular shape in a plan view. The first heating area S1 may be an area in which a cooking container C shown on the upper surface of the top plate 2 is arranged in a plan view. Alternatively, the first heating area S1 may be an area smaller than an area in which a cooking container C can be arranged in a plan view shown on the upper surface of the top plate 2.

[0030] In the first heating region S1, the coil pieces 10A to 10F are arranged adjacent to each other. Specifically, the coil pieces 10A to 10F are arranged radially in a plan view.

[0031] The first heating region S1 has multiple coil arrangement regions S11-S16. The multiple coil arrangement regions S11-S16 are arranged radially and adjacently around the center C1 of the first heating region S1 in a plan view. Specifically, the multiple coil arrangement regions S11-S16 are defined by multiple boundary lines L11-L16 that extend radially from the center C1 of the first heating region S1 toward the outer periphery in a plan view, and an outer periphery line L1 that defines the outer periphery of the first heating region S1.

[0032] The boundary lines L11-L16 are arranged radially at equal intervals around the center C1 of the first heating region S1 in plan view. The boundary lines L11-L16 are straight lines extending from the center C1 of the first heating region S1 toward the outer periphery in plan view. The angles between two adjacent boundary lines among the boundary lines L11-L16 are substantially the same. As a result, the coil arrangement regions S11-S16 have substantially the same shape and substantially the same dimensions in plan view. In this specification, "substantially" means within an error of 10%, and preferably within an error of 5%.

[0033] Each of the coil arrangement regions S11 to S16 has a sector shape in plan view. In this specification, the term "sector shape" refers to a shape defined by two straight lines (radii) extending from the center of a circle toward the outer periphery in plan view and an arc connecting the two straight lines. The coil arrangement regions S11 to S16 according to this embodiment have a sector shape in plan view, but are not limited thereto. For example, the coil arrangement regions S11 to S16 may have a shape defined by two straight lines extending from the center of a circle toward the outer periphery in plan view and a straight line connecting the two straight lines. The same applies to the coil arrangement regions S21 to S16 described later.

[0034] In this embodiment, the boundary lines include six boundary lines L11 to L16, and the angle between two adjacent boundary lines is 60 degrees. As a result, the first heating region S1 is divided into six coil arrangement regions S11 to S16 that have approximately the same shape and approximately the same dimensions in a plan view.

[0035] The coil pieces 10A to 10F are arranged in the coil arrangement regions S11 to S16, respectively, in a plan view. As a result, the coil pieces 10A to 10F are arranged radially and adjacent to each other in the first heating region S1 in a plan view.

[0036] The second heating area S2 is an area having a center C2 in a plan view, and is an area in which the multiple coil pieces 10E-10J are arranged. In the present embodiment, the second heating area S2 has a circular shape in a plan view. The second heating area S2 may be an area in which a cooking container C shown on the upper surface of the top plate 2 is arranged in a plan view. Alternatively, the second heating area S2 may be an area smaller than an area in which a cooking container C can be arranged in a plan view shown on the upper surface of the top plate 2.

[0037] In the second heating region S2, the coil pieces 10E to 10J are arranged adjacent to each other. Specifically, the coil pieces 10E to 10J are arranged radially in a plan view.

[0038] The second heating region S2 has multiple coil arrangement regions S21 to S26. The multiple coil arrangement regions S21 to S26 are arranged radially and adjacently around the center C2 of the second heating region S2 in a plan view. Specifically, the multiple coil arrangement regions S21 to S26 are defined by multiple boundary lines L21 to L26 that extend radially from the center C2 of the second heating region S2 toward the outer periphery in a plan view, and an outer periphery line L2 that defines the outer periphery of the second heating region S2.

[0039] The boundary lines L21 to L26 are arranged radially at equal intervals around the center C2 of the second heating region S2 in a plan view. The boundary lines L21 to L26 are straight lines extending from the center C2 of the second heating region S2 toward the outer periphery in a plan view. The angles between two adjacent boundary lines among the boundary lines L21 to L26 are substantially the same. As a result, the coil arrangement regions S21 to S26 have substantially the same shape and dimensions in a plan view.

[0040] Each of the multiple coil arrangement regions S21 to S26 has a sector shape in plan view.

[0041] In the present embodiment, the multiple boundary lines in the second heating region S2 include six boundary lines L21 to L26, and the angle between two adjacent boundary lines is 60 degrees. This divides the second heating region S2 into six coil arrangement regions S21 to S26 that have approximately the same shape and approximately the same dimensions in a plan view.

[0042] In this embodiment, each of the multiple coil arrangement regions S11 to S16, S21 to S26 is positioned so as to be adjacent to at least two coil arrangement regions.

[0043] In addition, in this embodiment, the two coil arrangement regions S21, S22 in the second heating region S2 overlap with the two coil arrangement regions S15, S16 in the first heating region S1.

[0044] The multiple coil pieces 10E-10J are arranged in multiple coil arrangement regions S21-S26, respectively, in a plan view. As a result, the multiple coil pieces 10E-10J are arranged radially and adjacent to each other in the second heating region S2 in a plan view.

[0045] The seventh to tenth coil pieces 10G-10J are arranged in the multiple coil arrangement regions S23-S26. The fifth and sixth coil pieces 10E-10F are arranged in the two coil arrangement regions S21, S22. That is, the fifth and sixth coil pieces 10E-10F are shared by the first heating region S1 and the second heating region S2. Therefore, some of the multiple coil pieces 10 arranged in the coil arrangement regions S11-S16 overlap with some of the multiple coil pieces 10 arranged in the coil arrangement regions S21-S26.

[0046] The third heating region S3 is a region in which the multiple coil pieces 10A to 10J are arranged in a plan view, and is a region that is heated by the multiple coil pieces 10A to 10J. The third heating region S3 overlaps with the first heating region S1 and the second heating region S2 in a plan view.

[0047] The detailed configuration of the first coil piece 10A will be described with reference to FIG.

[0048] 3, the first coil piece 10A arranged in the coil arrangement region S11 has a coil wire 11 arranged along two adjacent boundary lines L11, L12 and an outer circumferential line L1 connecting the two adjacent boundary lines L11, L12 in a plan view. The first coil piece 10A is formed by winding the coil wire 11. The coil wire 11 is made of a conductive wire material.

[0049] The coil wire 11 is arranged so as to wind around the boundary lines L11, L12 and the outer circumferential line L1 in the coil arrangement region S11 in a planar view. The coil wire 11 is arranged in a frame shape in a planar view. In the embodiment, since the coil arrangement region S11 is formed in a sector shape in a planar view, the outer shape of the coil wire 11 is also formed in a sector shape in a planar view. The outer shape of the coil wire 11 can be formed into any shape depending on the shape of the coil arrangement region S11.

[0050] The first coil piece 10A has straight portions 12 and 13, an outer peripheral portion 14, and connection portions 15, 16, and 17. The straight portion 12 is a substantially straight coil portion arranged along the boundary line L11. The straight portion 13 is a substantially straight coil portion arranged along the boundary line L12. The outer peripheral portion 14 is a curved coil portion arranged along the outer peripheral line L1. The outer peripheral portion 14 may be a substantially straight coil portion. The connection portion 15 is a coil portion that connects one end of the straight portion 12 and one end of the straight portion 13 on the center C1 side of the first heating region S1 in a plan view. The connection portion 16 is a coil portion that connects the other end of the straight portion 12 and one end of the outer peripheral portion 14 on the outer peripheral line L1 side of the first heating region S1 in a plan view. The connection portion 17 is a coil portion that connects the other end of the straight portion 13 and the other end of the outer peripheral portion 14 on the outer peripheral line L1 side of the first heating region S1 in a plan view. The connection portions 15, 16, and 17 are, for example, curved in a U-shape.

[0051] In this specification, "arranged along boundary lines L11, L12 or circumferential line L1" means, unless otherwise specified, that there are no other parts arranged to obstruct the boundary lines L11, L12 or circumferential line L1, and that the parts are arranged to extend in approximately the same direction as the boundary lines L11, L12 or circumferential line L1.

[0052] In this embodiment, the second to tenth coil pieces 10B to 10J have the same configuration as the first coil piece 10A. However, in the fifth coil piece 10E and the sixth coil piece 10F arranged in both the first heating region S1 and the second heating region S2, the coil portions arranged along some of the boundary lines (boundary lines L21 and L23 in this embodiment) are curved because they also serve as the coil portions arranged along the outer peripheral line of the first heating region S1 or the second heating region S2 (outer peripheral line L1 of the first heating region S1 in this embodiment). Also, in the fifth coil piece 10E and the sixth coil piece 10F, the coil portions arranged along the outer peripheral line of the first heating region S1 or the second heating region S2 (outer peripheral line L2 of the second heating region in this embodiment) are linear. In other words, in this embodiment, of the fifth to tenth coil pieces 10E to 10J arranged in the second heating region S2, the fifth and sixth coil pieces 10E, 10F are arranged so that the apexes that form the central angle of the sector face toward center C1 rather than center C2.

[0053] [Electrical connection configuration] 4 shows a schematic block diagram of electrical connections related to the coil unit 4 of the induction heating cooker 1. As shown in FIG. 4, the induction heating cooker 1 has a power supply unit 8, an inverter circuit 23, and the coil unit 4. The inverter circuit 23 is connected to the controller 6 and receives a control signal from the controller 6.

[0054] The power supply unit 8 is connected to a power supply such as a commercial AC power supply. When the power supply unit 8 is connected to a power supply, it converts the applied voltage of the power supply to a predetermined voltage and outputs it. In this embodiment, the power supply unit 8 has a rectifying and smoothing circuit including a diode bridge 21, which will be described in detail later, and a smoothing capacitor 22. The power supply unit 8 is connected to an inverter circuit 23, and applies the converted voltage to the inverter circuit 23 to supply power.

[0055] The inverter circuit 23 is connected to the power supply unit 8 and the coil unit 4. The inverter circuit 23 has, for example, a plurality of switching elements 27, 28, the details of which will be described later. Each of the switching elements 27, 28 of the inverter circuit 23 switches on / off based on a control signal received from the controller 6.

[0056] The controller 6 controls the operation of the inverter circuit 23 to control the current flowing through the multiple coil pieces 10 of the coil unit 4. Specifically, the controller 6 controls the operation of the inverter circuit 23 so that a high-frequency current flows through the multiple coil pieces 10 when the coil unit 4 heats an object to be heated. The controller 6 controls the on / off of the switching elements 27, 28 of the inverter circuit 23 so that a high-frequency current flows through each coil piece 10 by current resonance, for example, via the coil pieces 10 and resonant capacitors 24, 25, which will be described in detail later.

[0057] The induction heating cooker 1 according to the present embodiment is configured to supply high-frequency current to each coil piece 10 by current resonance to operate each coil piece 10, but is not limited to this. The induction heating cooker 1 may be configured to operate each coil piece 10 by any method. For example, the induction heating cooker 1 may be configured to operate each coil piece 10 by voltage resonance.

[0058] [circuit] FIG. 5 is a schematic circuit diagram showing an example of electrical connections of the induction heating cooker 1 according to the present embodiment. As described above, the induction heating cooker 1 includes a plurality of coil pieces 10A-10J constituting the coil unit 4. The induction heating cooker 1 also includes a diode bridge 21, a smoothing capacitor 22, a plurality of inverter circuits 23A-23J, and a plurality of resonant capacitors 24A-24J, 25A-25J as electronic components for realizing heating by the plurality of coil pieces 10A-10J. Hereinafter, when it is not necessary to distinguish between the plurality of inverter circuits 23A-23J, they will be collectively referred to as an inverter circuit 23 or a plurality of inverter circuits 23. When it is not necessary to distinguish between the plurality of resonant capacitors 24A-24J, they will be collectively referred to as a resonant capacitor 24 or a plurality of resonant capacitors 24. When it is not necessary to distinguish between the plurality of resonant capacitors 25A-25J, they will be collectively referred to as a resonant capacitor 25 or a plurality of resonant capacitors 25.

[0059] In the induction heating cooker 1, the coil pieces 10, the inverter circuits 23, and the resonant capacitors 24, 25 are connected in the same manner as the circuit related to the coil piece 10A. The coil pieces 10C-10I, the inverter circuits 23C-23I, and the resonant capacitors 24C-24I, 25C-25I are omitted in Fig. 5. The induction heating cooker 1 may have circuits of the same configuration for each of the multiple coil units 4, or may have circuits of different configurations.

[0060] The diode bridge 21 is connected to an AC power supply (e.g., a 100V or 200V commercial AC power supply) 20, and full-wave rectifies the AC voltage input from the AC power supply, converts it into a pulsating DC voltage, and applies it between the wiring 26a and 26b.

[0061] The smoothing capacitor 22 is connected between the wires 26 a and 26 b and smoothes the voltage applied from the diode bridge 21 .

[0062] In the inverter circuit 23A, the switching elements 27A and 28A are connected in series between the wirings 26a and 26b. Each of the switching elements 27A and 28A has an IGBT and a diode connected in anti-parallel to the IGBT. As described above, each of the switching elements 27A and 28A switches ON / OFF based on a control signal received from the controller 6. The inverter circuits 23B to 23J have switching elements 27B to 27J and switching elements 28B to 28J, respectively. The inverter circuits 23B to 23J have the same configuration as the inverter circuit 23A, and therefore their description is omitted. The switching elements 27B to 27J and switching elements 28B to 28J have the same configuration as the switching elements 27A and 28A, and therefore their description is omitted. When it is not necessary to distinguish between the multiple switching elements 27A to 27J, they are collectively referred to as the switching element 27 or multiple switching elements 27. When there is no need to distinguish between the multiple switching elements 28A to 28J, they will be collectively referred to as the switching element 28 or the multiple switching elements 28.

[0063] The resonant capacitors 24A and 25A are connected in series between the wirings 26a and 26b. Each of the resonant capacitors 24B to 24J and the resonant capacitors 25B to 25J is configured similarly to the resonant capacitors 24A and 25A.

[0064] One end of coil piece 10A is connected between switching element 27A and switching element 28A, and the other end is connected between resonant capacitor 24A and resonant capacitor 25A. Coil piece 10A is controlled so that a high-frequency current having predetermined parameters flows by switching elements 27A, 28A on / off. Each of the other coil pieces 10B to 10J has a similar configuration to coil piece 10A, so a description thereof will be omitted.

[0065] The controller 6 controls the operation of the inverter circuit 23 to control the current flowing through the multiple coil pieces 10 of the coil unit 4. Specifically, the controller 6 controls the operation of the inverter circuit 23 to control the inverter circuit 23 so that a high-frequency current always flows through the multiple coil pieces 10 when the coil unit 4 heats an object to be heated. The controller 6 can switch the heating mode by controlling the current flowing through each coil piece 10. In the embodiment according to the present disclosure, the circuit of the coil unit 4 includes, but is not limited to, multiple inverter circuits 23, and may be configured such that the current flowing through the multiple coil pieces 10 is controlled by a single inverter circuit.

[0066] [Operation] Next, the operation of the induction heating cooker 1 according to the embodiment of the present disclosure will be described.

[0067] The induction heating cooker 1 according to the embodiment of the present disclosure can control the intensity of local heating when heating an object placed on the top plate 2 on the coil unit 4. For example, the controller 6 of the induction heating cooker 1 can control the intensity of local heating by heating the object in one or more heating modes. The heating mode indicates a heating method that locally generates an area where heating is strong or weak. Therefore, when the controller 6 controls the object to be heated in a predetermined heating mode, a predetermined part of the object corresponding to the predetermined heating mode can be heated more strongly than other parts. The heating mode can be stored in the storage device of the controller 6 together with the parameters of the current that realizes the heating mode. Note that the control of the intensity of local heating by the controller 6 does not necessarily need to use a predetermined heating mode. For example, the parameters of the current that can heat a predetermined area strongly (or weakly) can be stored in the storage device, and when there are multiple areas that require strong heating, the controller 6 can control the heating by combining the stored information.

[0068] An example of a method for controlling the local intensity of heating of an object to be heated by the controller 6 according to this embodiment will be described below.

[0069] In the induction heating cooker 1, the multiple coil pieces 10 are arranged in multiple coil arrangement regions S11-S16, S21-S26 defined by the outer circumferential lines L1, L2 and multiple boundary lines L11-L16, L21-L26 as described above. For example, two adjacent first coil pieces 10A and second coil pieces 10B are arranged in two adjacent coil arrangement regions S11 and S12, respectively. The coil arrangement region S11 and the coil arrangement region S12 are defined by the shared boundary line L12. Therefore, a part of the first coil piece 10A and a part of the second coil piece 10B are arranged along the boundary line L12.

[0070] The controller 6 can control the currents flowing in the coil pieces 10A and 10B so that there is a predetermined phase difference between the current flowing in the portion of the coil piece 10A that is along the boundary line L12 and the current flowing in the portion of the coil piece 10B that is along the boundary line L12. The portion of the first coil piece 10A that is along the boundary line L12 corresponds to the straight portion 13 of the coil wire 11 shown in Fig. 3. The portion of the second coil piece 10B that is along the boundary line L12 corresponds to the straight portion 12 of the coil wire 11 when the first coil piece 10A shown in Fig. 3 is regarded as the second coil piece 10B.

[0071] For example, the controller 6 can control the current so that the predetermined phase difference is 0°, i.e., so that the currents are in phase. By controlling the current in this manner, the controller 6 can heat a portion of the heating object placed in a region corresponding to the portion where the first coil piece 10A and the second coil piece 10B are adjacent to each other more strongly than the other portions of the heating object. More specifically, the controller 6 can heat the portion of the heating object more strongly than the portion of the heating object placed in a region corresponding to the other portions of the first coil piece 10A and the second coil piece 10B. In this specification, the heating of the "portion of the heating object" by the coil piece 10 by the controller 6 is also referred to simply as heating the "heating object".

[0072] The region corresponding to the adjacent portion is, for example, a region located vertically above the corresponding portion (Z direction in FIG. 1) in a plan view. The region corresponding to the other portion is, for example, a region located vertically above a portion (such as a central portion or an outer circumferential portion) different from the adjacent portions of the coil pieces 10A, 10B in a plan view.

[0073] FIG. 6 is a graph showing an example of a current waveform when the phase difference between the currents flowing through adjacent portions of two adjacent coil pieces is 0°. More specifically, FIG. 6(a) is a graph showing the waveform of the current flowing through a portion along the boundary line L12 in the first coil piece 10A. FIG. 6(b) is a graph showing the waveform of the current flowing through a portion along the boundary line L12 in the second coil piece 10B. Each current waveform shown in FIG. 6 has the same frequency and the same amplitude, but is not limited thereto. The current waveform shown in FIG. 6 shows a case where the current flows clockwise in the first coil piece 10A and the second coil piece 10B in a plan view as a positive current. As shown in FIG. 6, the controller 6 controls the inverter circuit 23 so that the current flowing through the first coil piece 10A and the current flowing through the second coil piece 10B flow in the opposite directions, thereby controlling the current so that the phase difference between the currents flowing through adjacent portions is 0°.

[0074] Also, for example, the controller 6 can control the current so that the predetermined phase difference is 180°. By controlling the current in this manner, the controller 6 can heat a portion of the heating object placed in an area corresponding to the outer periphery of the first coil piece 10A and the second coil piece 10B more strongly than other portions of the heating object. More specifically, the controller 6 can heat the portion of the heating object placed in an area corresponding to the interior of the first coil piece 10A and the second coil piece 10B more strongly than other portions of the heating object.

[0075] When a current is passed through the first coil piece 10A and the second coil piece 10B, the region corresponding to the outer periphery is, for example, a region located vertically above the periphery of the first coil piece 10A and the second coil piece 10B (Z direction in FIG. 1) in a plan view. The region corresponding to the outer periphery may be a region located vertically above a portion of the first coil piece 10A and the second coil piece 10B along the boundary lines L11, L13 and the outer periphery line. When a current is passed through a plurality of coil pieces 10A to 10J, the region corresponding to the outer periphery is, for example, a region located vertically above the outer periphery of the coil unit 4. When a current is passed through the first coil piece 10A and the second coil piece 10B, the region corresponding to the interior is, for example, a region located vertically above the interior of the first coil piece 10A and the second coil piece 10B in a plan view. The region corresponding to the interior may be a region surrounded by the region corresponding to the outer periphery in a plan view.

[0076] FIG. 7 is a graph showing an example of a current waveform when the phase difference between the currents flowing through adjacent portions of two adjacent coil pieces is 180°. More specifically, FIG. 7(a) is a graph showing the waveform of the current flowing through a portion along the boundary line L12 in the first coil piece 10A. FIG. 7(b) is a graph showing the waveform of the current flowing through a portion along the boundary line L12 in the second coil piece 10B. Each current waveform shown in FIG. 7 has the same frequency and the same amplitude, but is not limited thereto. The current waveform shown in FIG. 7 shows a case where the current flows clockwise in the first coil piece 10A and the second coil piece 10B in a plan view as a positive current. As shown in FIG. 7, the controller 6 controls the inverter circuit 23 so that the current flowing through the first coil piece 10A and the current flowing through the second coil piece 10B flow in the same direction, thereby controlling the current so that the phase difference between the currents flowing through adjacent portions is 180°.

[0077] The predetermined phase difference is not limited to 0° or 180°, and may be 30°, 45°, 60°, or 90°, or may be another difference.

[0078] In addition, the controller 6 can locally control the strength of heating of the object to be heated by controlling the inverter circuit 23 so that there is a predetermined frequency difference between the currents flowing through the two adjacent coil pieces. That is, by controlling the inverter circuit 23 so that there is a predetermined frequency difference between the currents flowing through the first coil piece 10A and the second coil piece 10B, it is possible to locally control the strength of heating of the object to be heated. The frequency difference between the currents flowing through the first coil piece 10A and the second coil piece 10B may be, for example, 0 or an integer multiple of 1 or more of the frequency of the current flowing through one of the coil pieces 10. That is, the frequency difference may be an integer multiple of 0 or more of the frequency of the current flowing through one of the coil pieces 10. However, the frequency difference is not limited to these, and the controller 6 may control the inverter circuit 23 so that the frequency difference is other than an integer multiple of 0 or more. For example, the controller 6 may control the frequency and phase of the current so that the peaks of the amplitudes of the currents flowing through the coil pieces 10 at least partially coincide with each other.

[0079] In this way, the controller 6 can locally control the strength of heating of the object to be heated by passing a current having predetermined parameters through each coil piece 10. Therefore, the controller 6 can heat the object to be heated placed on the top plate 2 in a predetermined heating mode by controlling the current. The parameters include the amplitude, phase, and frequency of the current. The controller 6 can control the parameters of the current flowing through each coil piece 10, for example, by controlling the on / off of the inverter circuit 23. In the embodiment of the present disclosure, the predetermined heating modes include, but are not limited to, the first to sixth heating modes.

[0080] Fig. 8 is a schematic diagram showing an example of heating regions controlled by a first heating mode in an induction heating cooker according to an embodiment of the present disclosure. In Fig. 8, ten coil pieces 10A-10J are shown as the coil unit 4. In Fig. 8, the region S31 is a region capable of strongly heating an object to be heated. The region S31 is located at adjacent positions of two adjacent coil pieces 10 in a plan view. Moreover, the region S31 may be located at positions along each of a plurality of boundary lines L11-L16, L21-L26 or circumferential lines L1, L2 in each coil piece 10 in a plan view.

[0081] The controller 6 can heat a portion of the object placed in the region corresponding to the region S31 more strongly than other portions of the object by passing a current having parameters shown in Table 1 through each coil piece 10. The parameters shown in Table 1 are hereinafter referred to as first parameters as appropriate. The portion of the object placed in the region corresponding to the region S31 is, for example, a portion located vertically above the region S31 in a plan view (Z direction in FIG. 1).

[0082] [Table 1]

[0083] In Table 1, the relationship between the parameters of the current flowing through adjacent portions means the relationship between the parameters of the current flowing through adjacent portions of two adjacent coil pieces 10 (e.g., the first coil piece 10A and the second coil piece 10B). This relationship is similar to that in Tables 2 to 6 described below. As shown in Table 1, the currents flowing through adjacent portions in the first parameter have the same amplitude. The currents flowing through adjacent portions in the first parameter have the same phase (i.e., a phase difference of 0°). The currents flowing through adjacent portions in the first parameter have the same frequency. The controller 6 controls the current so that the first parameters shown in Table 1 are satisfied for all pairs of two adjacent coil pieces 10, thereby making it possible to heat the heating object in the first heating mode.

[0084] FIG. 9 is a distribution diagram of an example of the temperature of the heating object when the heating object is heated in the first heating mode. FIG. 9 shows a view of the heating object viewed from diagonally above. FIGS. 11 to 14 described later also show views of the heating object viewed from diagonally above, similar to FIG. 9. In FIG. 9, the region S32 is a region where the temperature of the heating object is high (i.e., a region that is strongly heated). As shown in FIG. 9, the inner part of the heating object is hotter than the outer part of the heating object located around the inner part. Therefore, it can be seen that the inner part of the heating object is heated more strongly than the outer part. In this specification, the "inner part" of the heating object means a part located radially outward from the central part of the heating object in a plan view. The "outer part" of the heating object means a part radially outward from the inner part of the heating object. The "central part" of the heating object means a part located vertically above the central parts of the first heating area S1 and the second heating area S2 in a plan view.

[0085] For example, the central portion of the first heating region S1 may be a portion including the connection portions 15 of each of the coil pieces 10A-10F and parts of the straight portions 12, 13. The central portion of the second heating region S2 may be a portion including the connection portions 15, parts of the straight portions 12, 13 of each of the coil pieces 10G-10J, the connection portion 17, parts of the straight portion 13, and parts of the outer circumferential portion 14 of the coil piece 10E, and the connection portion 16, straight portion 12, and parts of the outer circumferential portion 14 of the coil piece 10F.

[0086] The inner part of the object to be heated may be a part located vertically above an annular part formed by at least a part of the straight parts 12, 13 of each of the coil pieces 10A-10F and an annular part formed by at least a part of the straight parts 12, 13 of each of the coil pieces 10E-10J in a plan view. The inner part of the object to be heated may be a part located vertically above an annular part formed by parts of each of the coil pieces 10A-10J along the boundary lines L11-L16, L21-L26 in a plan view. The outer part of the object to be heated may be a part located vertically above the outer periphery of the coil unit 4. The outer part of the object to be heated may be a part located vertically above a part formed by the outer periphery parts 14 of each of the coil pieces 10A-10D, 10G-10H.

[0087] Specifically, the region that is heated more strongly in the first heating mode is a region that corresponds to adjacent portions of two adjacent coil pieces 10, as shown in FIG. 8. That is, the region includes a region that corresponds to a portion along the boundary lines L11-L16, L21-L26 in each coil piece 10. The region also includes a region that corresponds to a portion along the outer circumferential line L1 in the fifth and sixth coil pieces 10E-10F. In the first heating mode, the portion of the heating object in the region is heated more strongly than the other portions of the heating object. For example, the portion of the heating object in the region is heated more strongly than the portion of the heating object in the region that corresponds to a portion not adjacent to the other coil pieces 10 among the portions along the boundary lines and the portions along the outer circumferential line in each of the plurality of coil pieces 10. The portion of the heating object in the region that corresponds to the non-adjacent portion may be a portion located vertically above the non-adjacent portion.

[0088] Fig. 10 is a schematic diagram showing an example of a heating region controlled by the second heating mode in the induction heating cooker 1 according to the embodiment of the present disclosure. In Fig. 10, ten coil pieces 10A-10J are shown as the coil unit 4. In Fig. 10, the region S33 is a region capable of strongly heating an object to be heated. In a plan view, the region S33 is located on the outer periphery of the plurality of coil pieces 10 (i.e., the outer periphery of the coil unit 4). In a plan view, the region S33 may be located in a portion of each of the plurality of coil pieces 10 along the outer periphery lines L1 and L2 that is not adjacent to the other coil pieces 10.

[0089] The controller 6 can heat a portion of the object placed in the region corresponding to the region S33 more strongly than other portions of the object by passing a current having parameters shown in Table 2 through each coil piece 10. The parameters shown in Table 2 are hereinafter referred to as second parameters as appropriate. The portion of the object placed in the region corresponding to the region S33 is, for example, a portion located vertically above the region S33 in a plan view (Z direction in FIG. 1).

[0090] [Table 2]

[0091] As shown in Table 2, in the second parameters, the currents flowing through adjacent portions have the same amplitude. In the second parameters, the currents flowing through adjacent portions have opposite phases (i.e., a phase difference of 180°). In the second parameters, the currents flowing through adjacent portions have the same frequency. The controller 6 can heat the heating object in the second heating mode by controlling the current so that the second parameters shown in Table 2 are satisfied for all pairs of two adjacent coil pieces.

[0092] Fig. 11 is a distribution diagram of an example of the temperature of the heating object when the heating object is heated in the second heating mode. In Fig. 11, region S34 is a region where the temperature of the heating object is high (i.e., a region that is strongly heated). As shown in Fig. 11, the central part and the inner part of the heating object are lower in temperature than the outer part of the heating object. Therefore, it can be seen that the outer part of the heating object is heated more strongly than the central part and the inner part.

[0093] 10, the region that is heated more strongly in the second heating mode is a region that corresponds to the outer periphery of the coil unit 4. That is, a portion of the heating object in the region that corresponds to a portion along the boundary line and the outer periphery line of each of the multiple coil pieces 10 that is not adjacent to other coil pieces 10 is heated more strongly than other portions of the heating object. For example, the portion of the heating object in that region can be heated more strongly than a portion of the heating object in a region that corresponds to a central portion of at least one of the multiple coil pieces 10.

[0094] Furthermore, the controller 6 can heat the object to be heated in a heating mode different from the first heating mode and the second heating mode. For example, the controller 6 can heat the object to be heated in a third heating mode by passing a current having parameters shown in Table 3 through each coil piece 10. The parameters shown in Table 3 will hereinafter be appropriately referred to as third parameters.

[0095] [Table 3]

[0096] As shown in Table 3, in the third parameter, the currents flowing through adjacent portions have different amplitudes. In the third parameter, the currents flowing through adjacent portions have the same phase (i.e., a phase difference of 0°). In the third parameter, the currents flowing through adjacent portions have the same frequency. The controller 6 can heat the heating object in the third heating mode by controlling the current so that the third parameters shown in Table 3 are satisfied for all pairs of two adjacent coil pieces 10.

[0097] In the third heating mode, the controller 6 controls the current so that coil pieces with large current amplitudes and coil pieces with small current amplitudes are arranged alternately. In other words, the controller 6 controls the current so that a larger current flows through every other coil piece 10 among the multiple coil pieces 10 than through the other coil pieces 10. Therefore, in the third heating mode, the amplitude of the current flowing through each coil piece 10 has one of two values. However, the controller 6 may control the current so that the type of current amplitude is a value selected from three or more values, as described below.

[0098] FIG. 12 is a distribution diagram of an example of the temperature of the heating object when the heating object is heated in the third heating mode. In FIG. 12, the region S35 is a region where the temperature of the heating object is high (i.e., a region that is strongly heated). As shown in FIG. 12, a part of the inner part of the heating object is hotter than the central part of the heating object. For example, in the coil unit 4 shown in FIG. 8, when the amplitude of the current flowing through the coil pieces 10B, 10D, 10F, 10H, and 10J is larger than the amplitude of the current flowing through the coil pieces 10A, 10C, 10E, 10G, and 10I, the heating object can be heated in this manner. In this case, specifically, the parts of the heating object on the region corresponding to the parts adjacent to the boundary line in the coil pieces 10B, 10D, 10F, 10H, and 10J and the part adjacent to the outer circumferential line L1 in the coil piece 10F are heated more strongly than other parts.

[0099] In this way, the controller 6 can change the intensity of heating the object to be heated and the area to be heated strongly by changing the amplitude of the current flowing through each coil piece 10. Specifically, the controller 6 can heat the part of the object to be heated on the area corresponding to the part along each of the boundary lines in every other coil piece 10 among the coil pieces 10A to 10J more strongly than the other parts by controlling the current as shown in Table 3. The part of the object to be heated on the area corresponding to the part is, for example, an area located vertically above the part in a plan view. The other part may be, for example, a part of the object to be heated on the area corresponding to a part different from the above-mentioned part. Specifically, the other part may be a part of the object to be heated on the area located vertically above the part along each of the boundary lines in a coil piece 10 different from the every other coil piece 10 in a plan view. The other part may be a part of the object to be heated on the area located vertically above the inner part of the coil piece 10 different from the every other coil piece 10 in a plan view.

[0100] Also, for example, the controller 6 can heat the heating object in the fourth heating mode by passing a current having the parameters shown in Table 4 through each coil piece 10. The parameters shown in Table 4 will hereinafter be appropriately referred to as fourth parameters.

[0101] [Table 4]

[0102] As shown in Table 4, in the fourth parameter, the currents flowing through adjacent portions have different amplitudes. In the fourth parameter, the currents flowing through adjacent portions have opposite phases (i.e., a phase difference of 180°). In the fourth parameter, the currents flowing through adjacent portions have equal frequencies. The controller 6 can heat the heating object in the fourth heating mode by controlling the current so that the fourth parameter shown in Table 4 is satisfied for all pairs of two adjacent coil pieces.

[0103] In the fourth heating mode, the controller 6 controls the current so that coil pieces with large current amplitude and coil pieces with small current amplitude are arranged alternately. Therefore, in the fourth heating mode, the amplitude of the current flowing through each coil piece 10 has one of two values. However, as described below, the controller 6 may control the current so that the type of current amplitude is a value selected from three or more values.

[0104] Fig. 13 is a distribution diagram of an example of the temperature of the object to be heated when the object to be heated is heated in the fourth heating mode. In Fig. 13, region S36 is a region where the temperature of the object to be heated is high (i.e., a region that is strongly heated). As shown in Fig. 13, a part of the outer part of the object to be heated is hotter than the central part of the object to be heated. Also, a part of the outer part is hotter than the remaining part of the outer part. Therefore, it can be seen that the part of the outer part of the object to be heated is heated more strongly than the central part and the remaining part of the outer part.

[0105] For example, in the coil unit shown in Fig. 8, the object to be heated can be heated in this manner when the amplitude of the current flowing through coil pieces 10B, 10D, 10F, 10H, and 10J is greater than the amplitude of the current flowing through coil pieces 10A, 10C, 10E, 10G, and 10I. In this case, specifically, the portions of the object to be heated in the regions of coil pieces 10B, 10D, 10F, 10H, and 10J that correspond to the sites adjacent to circumferential lines L1 and L2 are heated more strongly than other portions.

[0106] In this way, the controller 6 can change the intensity of heating the object to be heated and the area to be heated strongly by changing the amplitude of the current flowing through each coil piece 10. Specifically, the controller 6 can heat the part of the object to be heated in the area corresponding to the part along the outer circumferential lines L1, L2 in every other coil piece 10 among the coil pieces 10A to 10J more strongly than the other parts by controlling the current as shown in Table 4. The part of the object to be heated in the area corresponding to the part is, for example, an area located vertically above the part in a plan view. The other part may be, for example, a part of the object to be heated in the area corresponding to a part different from the above-mentioned part. Specifically, the other part may be a part of the object to be heated in the area located vertically above the part along the outer circumferential lines L1, L2 in a coil piece 10 different from the every other coil piece 10 in a plan view.

[0107] Also, for example, the controller 6 can heat the heating object in the fifth heating mode by passing a current having the parameters shown in Table 5 through each coil piece 10. The parameters shown in Table 5 will hereinafter be appropriately referred to as fifth parameters.

[0108] [Table 5]

[0109] As shown in Table 5, in the fifth parameter, the currents flowing through adjacent parts have the same amplitude. In the fifth parameter, the currents flowing through adjacent parts have different phases. Specifically, in the fifth parameter, the currents flowing through adjacent parts have the same phase difference for all pairs of two adjacent coil pieces 10. The same phase difference is, for example, 60°, but is not limited to this. In the fifth parameter, the currents flowing through adjacent parts have the same frequency. The controller 6 can heat the heating object in the fifth heating mode by controlling the current so that the fifth parameter shown in Table 5 is obtained for all pairs of two adjacent coil pieces 10.

[0110] By heating in the fifth heating mode, the induction heating cooker 1 can heat the inner part of the heating object more strongly than the outer part of the heating object. Moreover, by heating in the fifth heating mode, the induction heating cooker 1 can heat a wider range of the inner part of the heating object compared to heating in the first heating mode. The region that is heated more strongly in the fifth heating mode is specifically the region corresponding to the vertical upper side of the coil unit 4.

[0111] The control of heating by the controller 6 is not limited to the first to fifth heating modes described above. The controller 6 can control heating in a heating mode different from the above heating modes by controlling the parameters of the current flowing through adjacent portions of two adjacent coil pieces so that the parameters have a different relationship from the first to fifth parameters. For example, the controller 6 can control the current having the parameters shown in Table 6 to flow through each coil piece 10. The parameters shown in Table 6 will hereinafter be referred to as the sixth parameters as appropriate.

[0112] [Table 6]

[0113] As shown in Table 6, in the sixth parameter, the currents flowing through adjacent portions have different amplitudes. In the sixth parameter, the currents flowing through adjacent portions have the same phase (i.e., a phase difference of 0°). In the sixth parameter, the currents flowing through adjacent portions have different frequencies. Compared to the first parameter, the sixth parameter does not have the same current amplitude and frequency. Due to this difference, the controller 6 can change the strength of heating by adjacent portions by controlling the current flowing through each coil piece 10 to have the sixth parameter.

[0114] For example, when the controller 6 reduces the amplitude of the current flowing through a specific coil piece 10, it can weaken the heating intensity of the region heated by the specific coil piece 10 compared to the heating intensity of regions heated by other coil pieces 10. The region heated by the specific coil piece 10 includes a region heated by adjacent portions between the specific coil piece 10 and a coil piece 10 adjacent to the specific coil piece 10.

[0115] In the sixth heating mode, the controller 6 changes the strength of the heating by using two types of current amplitude, but is not limited to this. For example, the controller 6 may change the strength of the heating by using three types of current amplitude.

[0116] In this way, the controller 6 can locally control the strength of heating of the object to be heated by the coil unit 4 by controlling at least one of the amplitude, phase, and frequency of the current flowing through adjacent portions.

[0117] In the induction heating cooker 1 according to the embodiment of the present disclosure, the controller 6 can control heating of the object to be heated using one or more of a plurality of heating modes having different distributions of local heat intensity on the object to be heated. For example, the controller 6 may control heating of the object to be heated using the first heating mode, or may control heating of the object to be heated using the second heating mode.

[0118] The controller 6 can control the heating of the object to be heated by switching between two or more of the multiple heating modes. The controller 6 may alternately switch between the two heating modes using, for example, two types of current parameters corresponding to the two heating modes, or may alternately switch between the two types of current parameters so as to change continuously or stepwise.

[0119] The controller 6 may have a sequence that combines a plurality of heating modes. By providing a plurality of sequences with different combinations of heating modes, the controller 6 can control heating in a plurality of appropriate heating modes according to the contents to be cooked by heating the object to be heated.

[0120] The controller 6 may have a first sequence that combines at least a first heating mode and a second heating mode. The controller 6 may set the first sequence as an initial value when controlling heating. The first sequence is a sequence that can increase the heat power in a combination of multiple heating modes. Therefore, if the user does not select another sequence, the controller 6 can control heating using a heating mode that can perform heating most efficiently. In addition, the controller 6 may have a second sequence that has a combination of heating modes different from the first sequence. When the user selects the second sequence, the controller 6 controls heating using a heating mode included in the second sequence.

[0121] In the induction heating cooker 1 according to the embodiment of the present disclosure, the controller 6 can obtain information on the temperature of the object to be heated. When the coil unit 4 heats the object to be heated, the magnetic field generated by each coil piece 10 affects the object to be heated, and a current is generated in the object to be heated, thereby heating the object to be heated. Since the magnetic field is affected by the object to be heated, the impedance of each coil piece 10 changes. In general, the impedance of the coil piece 10 changes depending on the presence or absence of the object to be heated placed in the range affected by the magnetic field generated by the coil piece 10 and the magnetism due to the material of the object. Since the impedance also changes depending on the temperature of the object to be heated, the controller 6 can obtain the change in the temperature of the object to be heated by obtaining the change in the characteristics of each coil piece 10, such as grasping the impedance of each coil piece 10. For example, the controller 6 can obtain the change in the temperature of the area of ​​the object to be heated that is heated by each coil piece 10, by obtaining the change in the characteristics of each coil piece 10. In other words, the controller 6 can use each coil piece 10 like a temperature sensor.

[0122] For example, the controller 6 can acquire changes in the characteristics of each coil piece 10 by providing a current sensor in the circuit to acquire the current flowing through each coil piece 10 and acquiring the change in the current value relative to the voltage value. The method of acquiring changes in the characteristics of each coil piece 10 is not limited to a current sensor, and for example, the controller 6 may acquire changes in the characteristics using a voltage sensor.

[0123] When the controller 6 acquires information on temperature from the coil pieces 10, the controller 6 can store the information as temperature information in the storage device. The temperature information can be, for example, relative and qualitative information between the coil pieces 10A to 10J. The temperature information is not limited to this, and can be a numerical value. The controller 6 can detect, for example, a location where the temperature is relatively low based on information that associates the positions of the coil pieces 10 with the temperature information acquired based on each of the coil pieces 10. Therefore, the controller 6 can control the parameters of the current flowing through each of the coil pieces 10 so as to strongly heat the location where the temperature is relatively low. In this way, the controller 6 can control the parameters of the current flowing through each of the coil pieces 10 based on information that associates the positions of the coil pieces 10 with the temperature information acquired based on each of the coil pieces 10.

[0124] For example, the controller 6 may change the amplitude of the current flowing through one or more coil pieces 10 based on the information. By changing the amplitude of the current, the controller 6 can control the heating intensity of the area heated by the coil pieces 10. Furthermore, the controller 6 may change the phase of the current flowing through any two adjacent coil pieces 10 based on the information. By changing the phase of the current, the controller 6 can control the position of the area strongly heated by the two adjacent coil pieces 10.

[0125] Furthermore, the controller 6 can determine whether or not an object to be heated is placed on the top plate 2 vertically above each coil piece 10 by passing a current through the multiple coil pieces 10 and acquiring changes in the characteristics of the multiple coil pieces 10. For example, when the controller 6 determines that an object to be heated is placed on the top plate 2, it controls the parameters of the current flowing through each of the multiple coil pieces 10 to control the heating area by one or more coil pieces 10 corresponding to the position where the object is placed. This allows the controller 6 to control the current so as to efficiently heat the position where the object to be heated is placed.

[0126] In the induction heating cooker 1 according to the present disclosure, the controller 6 controls the coil unit 4 to energize all of the coil pieces 10 when heating an object to be heated using the coil unit 4. Therefore, even if the user moves the object to be heated while it is being heated, the controller 6 can determine whether the object to be heated is placed on each coil piece 10, and can quickly change the heating area according to the determination result.

[0127] The object to be heated by the induction heating cooker 1 includes a cooking container such as a pot or frying pan that contains the object to be heated. Such a container may be made of a magnetic material such as iron, but is not limited to this, and may be made of multiple materials. The multiple materials may include a non-magnetic material such as aluminum in addition to the magnetic material. When the container is made of multiple materials, for example, the central part of the bottom surface may be made of a magnetic material, and the peripheral part (i.e., the outer periphery) may be made of a non-magnetic material. When the central part and the peripheral part of such a container whose outer periphery is made of a non-magnetic material are heated with the same intensity, the peripheral part will experience a smaller increase in temperature than the central part because the heating efficiency is lower than that of the central part.

[0128] As described above, according to the induction heating cooker 1 of the embodiment of the present disclosure, the controller 6 can control the local strength of heating. Therefore, when a container whose outer periphery is made of a non-magnetic material is placed on the top plate, the controller 6 can efficiently heat the container by controlling the current so as to strongly heat the area corresponding to the non-magnetic material. The controller 6 can determine whether or not a container made of a non-magnetic material is placed on the top plate, for example, based on a change in impedance of each of the coil pieces 10A to 10J. For example, the controller 6 can heat the outer periphery of the container placed on the top plate more strongly than other parts of the container by controlling the heating in the second heating mode at least temporarily. That is, the controller 6 can efficiently heat the container by controlling the current so that the phases of the currents flowing through the adjacent parts of the two adjacent coil pieces 10 are 180° different from each other at least temporarily.

[0129] Fig. 14A is a graph showing an example of temperature change of an object to be heated when the object is heated by an induction heating cooker having a conventional heating coil. In Fig. 14A, the vertical axis on the left indicates temperature (°C). The vertical axis on the right indicates the output (W) of the heating coil of the induction heating cooker. The horizontal axis indicates time (seconds). With regard to the temperature change shown in Fig. 14A, the object to be heated is a pot, which is a cooking container. As the temperature of the pot rises, the oil contained in the container, which is the object to be cooked, is heated.

[0130] Specifically, the graph shown in FIG. 14A shows an example of temperature change when about 800 g of oil is heated to about 200° C. using a conventional induction heating cooker. The graph shown in FIG. 14A shows temperature changes at multiple locations on the heated object. In FIG. 14A, line A shows the temperature of the radial center portion on the back side of the pot. Line B shows the temperature of the peripheral portion of the central portion on the back side of the pot. Line C shows the temperature of the radially outer outer portion on the back side of the pot. The portion related to line B is located between the portion related to line A and the portion related to line C. Thus, line B shows the inner temperature of the radially inner portion on the back side of the pot. Line A shows the temperature of the radial center of the pot (hereinafter, appropriately referred to as the central pot temperature). Line B shows the temperature of the radially inner portion of the pot (hereinafter, appropriately referred to as the inner pot temperature). Line C shows the temperature of the radially outer portion of the pot (hereinafter, appropriately referred to as the outer pot temperature). Line D shows the output of the heating coil.

[0131] In FIG. 14A, the controller of the conventional induction heating cooker starts heating at about 0 seconds. When heating starts, the temperatures rise as shown in FIG. 14A. The conventional induction heating cooker includes a heating coil arranged in a circular shape centered on the center of the heating area. Therefore, the object to be heated is heated strongly at the inner part located near the heating coil, and the central part is heated less strongly than the inner part. Also, the outer part is heated less strongly than the central part.

[0132] Therefore, as shown in FIG. 14A, when a heating object is heated by a conventional induction heating cooker, the temperature of the inner pan rises more than the temperature of the outer pan. In the example shown in FIG. 14A, 100 seconds after the start of heating, there is a difference of about 60°C between the temperature of the inner pan and the temperature of the outer pan. Because there is a temperature difference between the temperature of the inner pan and the temperature of the outer pan, there is also a temperature difference between the temperature of the oil located radially inside the pan (hereinafter, appropriately referred to as the inner oil temperature) and the temperature of the oil located radially outside the pan (hereinafter, appropriately referred to as the outer oil temperature). Therefore, in heating by a conventional induction heating cooker, the time required for the outer oil temperature to rise to 200°C is longer than the time required for the inner oil temperature to rise to 200°C.

[0133] Furthermore, when heating an object to be heated, an induction heating cooker controls the temperature of the object to be heated so that it does not exceed a predetermined temperature (e.g., 300°C). If the heating output of the heating coil is increased, there is a possibility that the temperature of the inner pot will reach the predetermined temperature before the temperature of the oil on the outside rises to 200°C. If the heating output is increased, the difference between the temperature of the inner pot and the temperature of the outer pot will become larger, increasing the possibility that the temperature of the inner pot will reach the predetermined temperature before the oil temperature rises to 200°C. Therefore, when heating with a conventional induction heating cooker, the heating time cannot be shortened by more than a certain time even if the output is simply increased.

[0134] In contrast, the induction heating cooker 1 according to the embodiment of the present disclosure can control the local strength of heat applied to the object to be heated, and therefore can reduce the heating time compared to conventional induction heating cookers. FIG. 14B is a graph showing an example of the temperature change of the object to be heated when the object is heated by the induction heating cooker 1 according to the embodiment of the present disclosure. In FIG. 14B, the vertical axis on the left indicates temperature (°C). The vertical axis on the right indicates the output (W) of the coil unit 4 of the induction heating cooker 1. The horizontal axis indicates time (seconds). With regard to the temperature change shown in FIG. 14B, the object to be heated is a pot, which is a cooking container. As the temperature of the pot rises, the oil, which is the object to be cooked and is contained in the container, is heated.

[0135] Specifically, the graph shown in Fig. 14B shows an example of temperature change when about 800 g of oil is heated to about 200°C using the induction heating cooker 1 according to the embodiment of the present disclosure. The graph shown in Fig. 14B shows temperature changes at multiple locations on the object to be heated. Lines A to D in Fig. 14B show the temperatures or output of the same object as lines A to D in Fig. 14A.

[0136] In FIG. 14B, the controller 6 of the induction heating cooker 1 starts heating at around 0 seconds. When heating starts, each temperature rises as shown in FIG. 14B. As described above, the induction heating cooker 1 includes a plurality of heating coils (i.e., a plurality of coil pieces 10) arranged radially from the centers C1 and C2 of the first heating region S1 and the second heating region in the heating region. Also, as described above, the controller 6 of the induction heating cooker 1 can control the local strength of heating by controlling the parameters of the current flowing through the plurality of coil pieces 10. In the example shown in FIG. 14B, the controller 6 heats the heating object by switching between the first heating mode and the second heating mode (i.e., in the first sequence).

[0137] For example, in the example of FIG. 14B, the controller 6 controls the heating in the first heating mode in the period t1. Therefore, in the period t1, the inner pan temperature rises more than the outer pan temperature. The controller 6 controls the heating in the second heating mode in the period t2. Therefore, in the period t2, the outer pan temperature rises more than the inner pan temperature. As can be seen from FIG. 14B, the controller 6 locally heats the inner and outer portions of the heating object by alternately switching between the first and second heating modes. As a result, the difference between the inner pan temperature and the outer pan temperature is smaller than in the example shown in FIG. 14A. As a result, the difference between the inner oil temperature and the outer oil temperature is also smaller.

[0138] In this way, the induction heating cooker 1 can heat the heating object as a whole, compared to the conventional induction heating cooker, and therefore can efficiently heat the heating object. For example, in the example of FIG. 14B, the controller 6 can control the heating of the heating object as a whole by heating the inner part of the heating object in the first heating mode and heating the outer part of the heating object in the second heating mode. In addition, since the inner part and the outer part of the heating object can be heated in a balanced manner, the induction heating cooker 1 can suppress the occurrence of local temperature rise as in the conventional induction heating cooker. Therefore, since the heating output by the coil unit 4 can be increased, the induction heating cooker 1 according to the embodiment can shorten the heating time compared to the conventional induction heating cooker. In the example of FIG. 14A and the example of FIG. 14B, heating is stopped when the oil temperature on the outside reaches 200°C. As shown in FIGS. 14A and 14B, the induction heating cooker 1 according to the embodiment can shorten the heating time compared to the conventional induction heating cooker.

[0139] [effect] According to the induction heating cooker 1 according to the embodiment, the following effects can be achieved.

[0140] The induction heating cooker 1 includes a top plate 2, a coil unit 4 disposed below the top plate 2, and a control unit 6 that controls heating of an object to be heated by the coil unit 4. The coil unit 4 has a plurality of coil pieces 10A-10J disposed in a heating region S3 that heats an object to be heated in a plan view. The heating region S3 includes a first heating region S1 and a second heating region S2 that partially overlaps with the first heating region S1. The heating region S3 has a plurality of coil arrangement regions S11-S16, S21-S26 defined by respective circumferential lines L1, L2 and a plurality of boundary lines L11-L16, L21-L26 in a plan view. The respective circumferential lines L1, L2 define the peripheries of the first heating region S1 and the second heating region S2. The boundary lines L11-L16, L21-L26 extend radially from the centers C1, C2 of the first heating region S1 and the second heating region S2 toward the outer periphery. The coil pieces 10A-10J are arranged in the coil arrangement regions S11-S16, S21-S26 in a plan view. The control unit 6 controls the heating of the object to be heated by passing a current through all of the coil pieces 10A-10J.

[0141] According to this configuration, the induction heating cooker 1 can efficiently heat the object to be heated. Specifically, the first heating region S1 and the second heating region S2 are divided into a plurality of coil arrangement regions S11-S16, S21-S26 by a plurality of boundary lines L11-L16, L21-L26 and the outer circumferential lines L1, L2. In each of the plurality of coil arrangement regions S11-S16, S21-S26, the coil wire 11 constituting the coil piece 10 is arranged along two adjacent boundary lines and an outer circumferential line L1 or L2 connecting the two adjacent boundary lines. As a result, the coil wire 11 of the coil pieces 10A-10F is arranged from the center C1 of the first heating region S1 toward the outer circumferential direction in a plan view, and the coil wire 11 of the coil pieces 10E-10J is arranged from the center C2 of the second heating region S2 toward the outer circumferential direction. As a result, the induction heating cooker 1 of the embodiment can reduce uneven heating. Also, the gaps between the coil pieces 10 can be made small and the variation in the gaps can be reduced. In the embodiment, the outer shape of the coil pieces 10 in a plan view is fan-shaped to match the outer shapes of the coil arrangement regions S11-S16 and S21-S26, so that heating unevenness can be further reduced, but the outer shape of the coil pieces 10 may be other than a fan shape. For example, the outer shape of the coil pieces 10 in a plan view may be an ellipse or a magatama shape. Furthermore, since the induction heating cooker 1 has heating regions including the first heating region S1 and the second heating region S2, it can efficiently heat even an oval-shaped cooking vessel or a cooking vessel with a large diameter.

[0142] Moreover, according to the induction heating cooker 1 according to the embodiment, the control unit 6 controls the heating of the object to be heated while passing a current through all of the coil pieces 10A to 10J. Therefore, since the control unit 6 passes current through all of the coil pieces 10A to 10J, it is possible to prevent the current from concentrating on one of the coil pieces 10A to 10J, and the object to be heated can be heated with a high overall output. In addition, since all of the coil pieces 10A to 10J are constantly energized, the response speed is fast. Therefore, each of the coil pieces 10A to 10J can respond quickly to an instruction from the control unit 6. In addition, the control unit 6 can control the response speed of each of the coil pieces 10A to 10J, for example, by gradually changing the current parameters.

[0143] Furthermore, in the induction heating cooker 1, the control unit 6 controls at least some of the parameters of the current flowing through each of the multiple coil pieces 10A-10J to control the local strength of heating of the object to be heated. The parameters include the amplitude, phase, and frequency of the current. In this way, the control unit 6 of the induction heating cooker 1 can locally control the strength of heating of the object to be heated placed on the coil unit 4 by controlling at least some of the parameters of the current flowing through each of the multiple coil pieces 10A-10J. Therefore, the induction heating cooker 1 can efficiently heat the object to be heated.

[0144] In the induction heating cooker 1, some of the coil pieces 10E, 10F arranged in the coil arrangement areas S11-S16 of the first heating area S1 overlap with some of the coil pieces 10E, 10F arranged in the coil arrangement areas S21-S26 of the second heating area S2. With this configuration, the induction heating cooker 1 can reduce the space required for the coil unit 4.

[0145] Moreover, in the induction heating cooker 1, the multiple coil pieces 10 include ten coil pieces 10A-10J. Thus, the induction heating cooker 1 has ten coil pieces 10A-10J as the coil unit 4. By using the ten coil pieces 10, the induction heating cooker 1 can efficiently locally change the strength of heating, and can efficiently heat an object to be heated. Furthermore, the induction heating cooker 1 can reduce uneven heating.

[0146] In the induction heating cooker 1, the control unit 6 controls the current flowing to each portion along the boundary line between the two adjacent coil pieces among the boundary lines L11-L16, L21-L26 or the outer circumferential line L1, L2 between the two adjacent coil pieces in each pair of the two adjacent coil pieces among the multiple coil arrangement regions S11-S16, S21-S26 among the multiple coil arrangement regions. The control unit 6 controls the current flowing to each of the multiple coil pieces 10A-10J so that the current flowing to each portion has at least one of a predetermined amplitude difference, a predetermined phase difference, and a predetermined frequency difference. By controlling in this way, the control unit 6 of the induction heating cooker 1 can locally control the strength of heating for the heating object placed on the coil unit 4 or on its outer periphery. Therefore, the induction heating cooker 1 can efficiently heat the heating object.

[0147] In the induction heating cooker 1, the control unit 6 controls the heating of the object to be heated using one or more of a plurality of heating modes having different distributions of heat intensity for the object to be heated. By controlling in this way, the induction heating cooker 1 can locally change the heat intensity for the object to be heated and perform heating. Therefore, the induction heating cooker 1 can efficiently heat the object to be heated.

[0148] In the induction heating cooker 1, the multiple heating modes include a first heating mode. The first heating mode controls the current flowing through each of the multiple coil pieces 10A to 10J to heat the heating object in a region corresponding to adjacent portions of two adjacent coil pieces among the multiple coil pieces 10A to 10J more strongly than the heating object in a region corresponding to a portion not adjacent to other coil pieces among the portions along the multiple boundary lines L11 to L16, L21 to L26 and the portions along the outer circumferential lines L1 and L2 in each of the multiple coil pieces 10A to 10J. As a result, the induction heating cooker 1 can execute the first heating mode in which a portion of the heating object arranged above the adjacent portions of the two adjacent coil pieces in a plan view is heated more strongly than other portions of the heating object. Therefore, the induction heating cooker 1 can locally heat a portion of the heating object more strongly, and can efficiently heat the heating object.

[0149] In the induction heating cooker 1, the multiple heating modes include a second heating mode. The second heating mode controls the current flowing through each of the multiple coil pieces 10A to 10J to heat the heating object in the region corresponding to the portion along the outer circumferential lines L1, L2 of each of the multiple coil pieces 10A to 10J that is not adjacent to the other coil pieces more strongly than the heating object in the region corresponding to the portion along the boundary lines L11 to L16, L21 to L26 and the portion along the outer circumferential lines L1, L2 of each of the multiple coil pieces 10A to 10J that is adjacent to the other coil pieces. As a result, the induction heating cooker 1 can execute the second heating mode in which a portion of the heating object arranged above the portion along the outer circumferential lines L1, L2 of each coil piece 10 that is not adjacent to the other coil pieces 10 in a plan view is heated more strongly than the other portions of the heating object. Therefore, the induction heating cooker 1 can locally heat a part of the heating object more strongly, and can efficiently heat the heating object.

[0150] In the induction heating cooker 1, each of the coil arrangement regions S11-S16, S21-S26 is located so as to be adjacent to at least two coil arrangement regions. The multiple heating modes include a third heating mode. The third heating mode controls the current flowing through each of the coil pieces 10A-10J to heat the heating object in the region corresponding to the portion along each of the boundary lines L11-L16, L21-L26 in every other coil piece among the coil pieces 10A-10J more strongly than the heating object in the region corresponding to the other portion. As a result, the induction heating cooker 1 can execute the third heating mode in which the portion of the heating object arranged above the portion along the boundary lines L11-L16, L21-L26 in every other coil piece 10 in a plan view is heated more strongly than the other portions of the heating object. For example, the induction heating cooker 1 can heat the portion of the object to be heated more strongly than the portions of the object to be heated in the regions of the coil pieces other than the alternate coil pieces that correspond to the portions along the boundary lines L11-L16, L21-L26. Therefore, the induction heating cooker 1 can locally heat a portion of the object to be heated strongly, and can efficiently heat the object to be heated.

[0151] In the induction heating cooker 1, each of the coil arrangement regions S11-S16, S21-S26 is located so as to be adjacent to at least two coil arrangement regions. The multiple heating modes include a fourth heating mode. The fourth heating mode controls the current flowing through each of the coil pieces 10A-10J to heat the heating object in the region corresponding to the portion along the outer circumferential lines L1, L2 in every other coil piece among the coil pieces 10A-10J more strongly than the heating object in the region corresponding to the other portion. This allows the induction heating cooker 1 to execute a third heating mode in which, in a plan view, a portion of the heating object arranged above the portion along the outer circumferential lines L1, L2 in every other coil piece 10 is heated more strongly than the other portion of the heating object. For example, the induction heating cooker 1 can heat the portion of the heating object more strongly than a portion of the heating object in the region corresponding to the portion along the outer circumferential lines L1, L2 in a coil piece other than the every other coil piece. Therefore, the induction heating cooker 1 can locally and strongly heat a part of the object to be heated, and can efficiently heat the object to be heated.

[0152] In the present embodiment, the coil arrangement regions S11 to S16 and S21 to S26 have substantially the same shape and size, but are not limited thereto. For example, the coil arrangement regions S11 to S16 and S21 to S26 may have different shapes and / or different sizes.

[0153] In the present embodiment, the coil pieces 10 have substantially the same shape and substantially the same size, but the present invention is not limited to this. For example, the coil pieces 10 may have different shapes and / or different sizes.

[0154] In the present embodiment, an example has been described in which the boundary lines L11-L16 are straight lines extending from the center C1 of the first heating region S1 toward the periphery in a plan view, but the present invention is not limited thereto. Also, an example has been described in which the boundary lines L21-L26 are straight lines extending from the center C2 of the second heating region S2 toward the periphery in a plan view, but the present invention is not limited thereto. For example, the boundary lines L11-L16 may be curved lines extending from the center C1 of the first heating region S1 toward the periphery in a plan view.

[0155] In the present embodiment, each of the coil pieces 10A-10J is connected to a common diode bridge 21 and smoothing capacitor 22, but is not limited to this. For example, the induction heating cooker 1 may be configured to include two sets of a diode bridge 21 and a smoothing capacitor 22, the two sets being connected in parallel to the AC power supply 20, and each of the coil pieces 10A-10J being connected to one of the two sets. With this configuration, the diode bridge 21 for supplying power to the multiple coil pieces 10 is separate, so that the controller 6 can easily detect the power.

[0156] In the present embodiment, the coil pieces 10A-10J are connected to different inverter circuits 23A-23J, respectively, but are not limited thereto. For example, the induction heating cooker 1 may be configured such that two coil pieces 10 are connected to one inverter circuit 23. For example, one end of each of the two coil pieces 10 connected in parallel may be connected between the switching elements 27, 28, and the other end of the coil piece 10 may be connected between the resonance capacitors 24, 25. With this configuration, the number of parts can be reduced, and therefore the induction heating cooker 1 can be reduced in cost.

[0157] (Modification) Modifications of the embodiment will now be described.

[0158] In the embodiment, an example in which the number of the multiple coil arrangement regions S11-S16, S21-S26 is 10 has been described, but the present invention is not limited to this. Also, an example in which the number of the multiple coil pieces 10 is 10 has been described, but the present invention is not limited to this. The number of the multiple coil arrangement regions may be seven. Also, the number of the multiple coil pieces may be seven.

[0159] Fig. 15 shows a plan view of an example of a coil unit 4A included in an induction heating cooker 1 of a modified example. As shown in Fig. 15, the coil unit 4A includes a plurality of coil pieces 40A to 40G. In the modified example, differences from the embodiment will be mainly described. In the modified example, configurations that are the same as or similar to those in the embodiment will be described with the same reference numerals. Also, in the modified example, descriptions that overlap with those in the embodiment may be omitted.

[0160] As shown in Fig. 15, in plan view, a first heating region S1, a second heating region S2, and a third heating region S3 are defined. Four coil pieces 40A-40D are arranged in the first heating region S1. Four coil pieces 40D-40G are arranged in the second heating region S2. Seven coil pieces 40A-40G are arranged in the third heating region S3. The three coil pieces 40E-40G are arranged on the back side in the depth direction (Y-axis direction) of the four coil pieces 40A-40D in plan view. Hereinafter, when there is no need to distinguish between the multiple coil pieces 40A-40G, they will be collectively referred to as a coil piece 40 or multiple coil pieces 40.

[0161] The first heating region S1 has four coil arrangement regions S11 to S14. The four coil arrangement regions S11 to S14 are arranged radially and adjacently around the center C1 of the first heating region S1 in a plan view. Specifically, the four coil arrangement regions S11 to S14 are defined by a plurality of boundary lines L11 to L14 extending radially from the center C1 of the first heating region S1 toward the outer periphery in a plan view, and an outer periphery line L1 that defines the outer periphery of the first heating region S1. In the coil unit 4A, the four coil pieces 40A to 40D are respectively arranged in the four coil arrangement regions S11 to S14.

[0162] In the modified example, the plurality of boundary lines in the first heating region S1 include four boundary lines L11 to L14, and the angle between adjacent boundary lines is 90 degrees.

[0163] The second heating region S2 has four coil arrangement regions S21 to S24. The four coil arrangement regions S21 to S24 are arranged radially and adjacently around the center C2 of the second heating region S2 in a plan view. Specifically, the four coil arrangement regions S21 to S24 are defined by a plurality of boundary lines L21 to L24 extending radially from the center C2 of the second heating region S2 toward the outer periphery in a plan view, and an outer periphery line L2 that defines the outer periphery of the second heating region S2. In the coil unit 4A, the four coil pieces 40D to 40G are respectively arranged in the four coil arrangement regions S21 to S24.

[0164] In the modified example, the plurality of boundary lines in the second heating region S2 include four boundary lines L21 to L24, and the angle between adjacent boundary lines is 90 degrees.

[0165] In the modified example, the coil arrangement region S21 in the second heating region S2 overlaps with the coil arrangement region S14 in the first heating region S1. The coil piece 10D is shared by the first heating region S1 and the second heating region S2. Therefore, some of the multiple coil pieces 40 arranged in the coil arrangement regions S11-S14 overlap with some of the multiple coil pieces 40 arranged in the coil arrangement regions S21-S24.

[0166] The third heating region S3 is a region in which the multiple coil pieces 40A to 40G are arranged in a plan view, and is a region that is heated by the multiple coil pieces 40A to 40G. The third heating region S3 overlaps with the first heating region S1 and the second heating region S2 in a plan view.

[0167] Thus, in the induction heating cooker 1 of the modified example, the multiple coil pieces 40 include seven coil pieces 40A-40G. Thus, the induction heating cooker 1 has seven coil pieces 40A-40G as the coil unit 4. By using the seven coil pieces 40, the induction heating cooker 1 can efficiently locally change the strength of heating, and can efficiently heat the object to be heated. Furthermore, the induction heating cooker 1 can reduce uneven heating.

[0168] Even with such a configuration, the induction heating cooker 1 can achieve the effects of the present disclosure.

[0169] (Summary of aspects) As is apparent from the above description, the present disclosure includes the following aspects. In the following, reference symbols are given in parentheses only to clearly indicate the correspondence with the embodiments.

[0170] (Aspect 1) The induction heating cooker (1) according to the present disclosure includes a top plate (2), A coil unit (4) disposed below the top plate; A control unit (6) for controlling heating of an object to be heated by the coil unit; Equipped with the coil unit has a plurality of coil pieces (10A to 10J, 40A to 40G) that are arranged in a heating region (S3) that heats the object to be heated in a plan view, The heating region includes a first heating region (S1) and a second heating region (S2) partially overlapping the first heating region, The heating region has a plurality of coil arrangement regions (S11 to S16, S21 to S26) defined by each outer periphery line (L1, L2) that defines the outer periphery of each of the first heating region and the second heating region, and a plurality of boundary lines (L11 to L16, L21 to L26) that extend radially from the center (C1, C2) of each of the first heating region and the second heating region toward the outer periphery, in a plan view; the plurality of coil pieces are arranged within the plurality of coil arrangement regions in a plan view, The control unit controls heating of the object to be heated while passing a current through all of the plurality of coil pieces.

[0171] (Aspect 2) In the induction heating cooker (1) of aspect 1, the control unit (6) controls at least a portion of parameters of the current flowing through each of the plurality of coil pieces (10A to 10J, 40A to 40G) to control the local strength of heating of the object to be heated, and the parameters may include the amplitude, phase, and frequency of the current.

[0172] (Aspect 3) In the induction heating cooker (1) of Aspect 1 or Aspect 2, a portion (10E-10F, 40D) of the plurality of coil pieces arranged in the plurality of coil arrangement areas (S11-S16) of the first heating area (S1) and a portion (10E-10F, 40D) of the plurality of coil pieces arranged in the plurality of coil arrangement areas (S21-S26) of the second heating area (S2) may overlap.

[0173] (Aspect 4) In the induction heating cooker (1) of any of Aspects 1 to 3, the plurality of coil pieces (10A to 10J, 40A to 40G) may include ten coil pieces (10A to 10J) or seven coil pieces (40A to 40G).

[0174] (Aspect 5) In the induction heating cooker (1) of any of aspects 1 to 4, the control unit (6) may control, in each pair of two adjacent coil pieces among the plurality of coil pieces (10A to 10J, 40A to 40G) arranged in each of two adjacent coil arrangement regions among the plurality of coil arrangement regions (S11 to S16, S21 to S26), a current flowing through each of the plurality of coil pieces such that a current flowing through each portion along a boundary line between the two adjacent coil pieces among the plurality of boundary lines (L11 to L16, L21 to L26) or along the outer circumferential line (L1, L2) between the two adjacent coil pieces has at least one of a predetermined amplitude difference, a predetermined phase difference, and a predetermined frequency difference.

[0175] (Aspect 6) In the induction heating cooker (1) of aspect 5, the control unit (6) may control heating of the object to be heated using one or more heating modes among a plurality of heating modes having different distributions of local heat intensity on the object to be heated.

[0176] (Aspect 7) In the induction heating cooker (1) of aspect 6, the plurality of heating modes may include a first heating mode in which the current flowing through each of the plurality of coil pieces (10A to 10J, 40A to 40G) is controlled to heat the object to be heated in an area corresponding to adjacent portions of two adjacent coil pieces among the plurality of coil pieces more strongly than the object to be heated in an area corresponding to portions along the plurality of boundary lines (L11 to L16, L21 to L26) of each of the plurality of coil pieces and portions along the outer circumferential line (L1, L2) that are not adjacent to other coil pieces.

[0177] (Aspect 8) In the induction heating cooker (1) of aspect 6 or aspect 7, the plurality of heating modes may include a second heating mode in which the current flowing through each of the plurality of coil pieces (10A to 10J, 40A to 40G) is controlled to heat the object to be heated in a region of each of the plurality of coil pieces that corresponds to a portion along the outer circumferential line (L1, L2) that is not adjacent to other coil pieces more strongly than the object to be heated in a region of each of the plurality of coil pieces that corresponds to a portion along the boundary line (L11 to L16, L21 to L26) and a portion along the outer circumferential line that is adjacent to other coil pieces.

[0178] (Aspect 9) In the induction heating cooker (1) of any one of aspects 6 to 8, each of the plurality of coil arrangement areas (S11 to S16, S21 to S26) is located adjacent to at least two coil arrangement areas, The multiple heating modes may include a third heating mode in which the current flowing through each of the multiple coil pieces (10A to 10J, 40A to 40G) is controlled to heat the heating object in an area corresponding to a portion along each of the multiple boundary lines (L11 to L16, L21 to L26) in every other coil piece of the multiple coil pieces more strongly than the heating object in an area corresponding to the other portion.

[0179] (Aspect 10) In the induction heating cooker (1) of any one of aspects 6 to 9, each of the plurality of coil arrangement areas (S11 to S16, S21 to S26) is located adjacent to at least two coil arrangement areas, The multiple heating modes may include a fourth heating mode in which the current flowing through each of the multiple coil pieces is controlled to heat the heating object in an area corresponding to a portion along the outer circumferential line (L1, L2) of every other coil piece of the multiple coil pieces more strongly than the heating object in an area corresponding to the other portion.

[0180] In this specification, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as expressing or implying the relative importance or ranking of technical features. Features qualified as "first" and "second" expressly or imply the inclusion of one or more of that feature.

[0181] The induction heating cooker described in the present disclosure is realized by cooperation between hardware resources, such as a processor and a memory, and software (computer program). [Industrial Applicability]

[0182] According to the present disclosure, an induction heating cooker capable of efficiently heating an object to be heated by a plurality of heating coils can be provided, and therefore can be suitably used in this type of industrial field. [Explanation of symbols]

[0183] 1 induction cooker 2 Top plate 4 Coil unit 6 Controller 10,10A~10J coil piece 23 Inverter circuit S1 1st heating area S2 2nd heating area S3 3rd heating area S11~S16, S21~S26 Coil placement area L11~L16, L21~L26 boundary line L1, L2 outer perimeter line

Claims

1. A top plate and A coil unit disposed below the top plate; A control unit that controls heating of an object to be heated by the coil unit; Equipped with the coil unit has a plurality of coil pieces that are arranged in a heating region that heats the heating object in a plan view, the heating region includes a first heating region and a second heating region partially overlapping the first heating region; The heating region has a plurality of coil arrangement regions defined by respective outer periphery lines defining the outer periphery of each of the first heating region and the second heating region in a plan view, and a plurality of boundary lines extending radially from the center of each of the first heating region and the second heating region toward the outer periphery, the plurality of coil pieces are arranged within the plurality of coil arrangement regions in a plan view, The control unit controls heating of the object to be heated while passing a current through all of the plurality of coil pieces. Induction heating cooker.

2. 2. The induction heating cooker of claim 1, wherein the control unit controls the local strength of heating of the object to be heated by controlling at least a portion of parameters of the current flowing through each of the plurality of coil pieces, the parameters including the amplitude, phase and frequency of the current.

3. 2. The induction heating cooker according to claim 1, wherein a portion of the coil pieces arranged in the coil arrangement areas of the first heating area overlaps with a portion of the coil pieces arranged in the coil arrangement areas of the second heating area.

4. The induction heating cooker according to claim 1 , wherein the plurality of coil pieces includes ten coil pieces or seven coil pieces.

5. 5. The induction heating cooker according to claim 1, wherein the control unit controls the current flowing through each of the plurality of coil pieces in each pair of two adjacent coil pieces among the plurality of coil pieces arranged in each of two adjacent coil arrangement regions among the plurality of coil arrangement regions, so that the current flowing through each portion along the boundary line between the two adjacent coil pieces or the outer circumferential line between the two adjacent coil pieces among the plurality of boundary lines has at least one of a predetermined amplitude difference, a predetermined phase difference, and a predetermined frequency difference.

6. The induction heating cooker according to claim 5 , wherein the control unit controls heating of the object to be heated using one or more of a plurality of heating modes having different distributions of local heat intensity on the object to be heated.

7. 7. The induction heating cooker according to claim 6, wherein the multiple heating modes include a first heating mode in which the current flowing through each of the multiple coil pieces is controlled to heat the object to be heated in an area corresponding to adjacent portions of two adjacent coil pieces among the multiple coil pieces more strongly than the object to be heated in an area corresponding to portions along the multiple boundary lines and portions along the outer circumferential line of each of the multiple coil pieces that are not adjacent to other coil pieces.

8. 7. The induction heating cooker according to claim 6, wherein the plurality of heating modes include a second heating mode in which the current flowing through each of the plurality of coil pieces is controlled to heat the object to be heated in a region of each of the plurality of coil pieces that corresponds to a portion along the outer circumferential line that is not adjacent to other coil pieces more strongly than the object to be heated in a region of each of the plurality of coil pieces that corresponds to a portion along the boundary line and a portion along the outer circumferential line that is adjacent to other coil pieces.

9. Each of the plurality of coil arrangement regions is located adjacent to at least two other coil arrangement regions, the plurality of heating modes include a third heating mode in which a current flowing through each of the plurality of coil pieces is controlled to heat a heating object in an area corresponding to a portion along each of the plurality of boundary lines in every other coil piece among the plurality of coil pieces more strongly than a heating object in an area corresponding to another portion.

7. The induction heating cooker according to claim 6.

10. Each of the plurality of coil arrangement regions is located adjacent to at least two other coil arrangement regions, the plurality of heating modes include a fourth heating mode in which a current flowing through each of the plurality of coil pieces is controlled to heat a heating object in an area corresponding to a portion along the outer circumferential line in every other coil piece among the plurality of coil pieces more strongly than a heating object in an area corresponding to another portion.

7. The induction heating cooker according to claim 6.

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