Induction heating cooker

Abstract

The disclosed induction heating cookware includes a plurality of heating coils. A plurality of heating coils are disposed to heat an object to be heated on the top plate. Each of the plurality of heating coils includes a coil substrate formed by stacking a plurality of pattern layers of six or more layers, each of the plurality of pattern layers having a coil pattern formed therein. The coil substrate includes a plurality of series pattern groups, each series pattern group including a plurality of coil patterns connected in series. The plurality of series pattern groups are connected in parallel.

Description

Technical Field

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

[0002] In order to make the induction heating cooker thinner or lighter, it has been considered to make the heating coil used in the induction heating cooker thinner. To achieve the thinning of the heating coil, it is considered to use a coil substrate of the printed circuit board (PCB board) type for a contactless power supply disclosed in Patent Document 1 (Japanese Patent Application Publication No. 2019-186235) and Patent Document 2 (Japanese Patent Application Publication No. 2019-41273). Summary of the Invention

[0003] [Solution to the problem]

[0004] An induction heating cooker according to one aspect of the present disclosure may include a top plate on which an object to be heated is placed and a plurality of heating coils. The plurality of heating coils are configured to heat the object to be heated on the top plate. Each of the plurality of heating coils may include a coil substrate formed by stacking six or more layers of multiple pattern layers, each of the multiple pattern layers having a coil pattern formed therein. The coil substrate may include a plurality of series pattern groups, each series pattern group including a plurality of coil patterns connected in series. The plurality of series pattern groups may be connected in parallel. An inverter circuit supplies alternating current to the heating coils. A processor controls the inverter circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 is a schematic diagram of an induction heating cooker according to an embodiment of the present disclosure.

[0006] Figure 2 is a plan view schematically showing a coil substrate according to an embodiment of the present disclosure.

[0007] Figure 3 is a cross-sectional view schematically showing a coil substrate having a 16-layer structure according to an embodiment of the present disclosure.

[0008] Figure 4 is a plan view schematically illustrating coil patterns of a first layer and a second layer of a coil substrate having a 6-layer structure according to an embodiment of the present disclosure.

[0009] Figure 5 is a schematic diagram illustrating an example of wiring of a coil substrate having a 6-layer structure according to an embodiment of the present disclosure.

[0010] Figure 6A and Figure 6B is a schematic diagram illustrating an example of wiring of a coil substrate having a 6-layer structure according to an embodiment of the present disclosure.

[0011] Figure 7 is a schematic diagram illustrating an example of wiring of a coil substrate having a 12-layer structure according to an embodiment of the present disclosure.

[0012] Figure 8 is a schematic diagram illustrating an example of wiring of a coil substrate having a 12-layer structure according to an embodiment of the present disclosure.

[0013] Figure 9 Is displayed in Figure 7 and Figure 8 The experimental results of coil loss in the example of wiring of the coil substrate having a 12-layer structure are shown. DETAILED DESCRIPTION

[0014] It should be understood that the various embodiments in this document and the terms used therein are not intended to limit the technical features described herein to specific embodiments, and that the present disclosure includes various modifications, equivalents, or substitutes of the embodiments.

[0015] With respect to the description of the drawings, the same reference numerals may be used to designate the same or related elements.

[0016] A singular form of a noun corresponding to an item may include one or more of that item unless the context clearly dictates otherwise.

[0017] As used herein, each of phrases such as "A or B," "at least one of A and B," "at least one of A or B," "A, B or C," "at least one of A, B and C," and "at least one of A, B or C" may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.

[0018] The term "and / or" includes any combination of the listed associations or any one of the listed elements of the listed associations.

[0019] Terms such as “first,” “second,” etc. may be used simply to distinguish an element from other elements, and do not limit the elements in any other respect (eg, importance or order).

[0020] It should be understood that when an element (e.g., a first element) is referred to as being “coupled” or “connected” to another element (e.g., a second element), with or without the term “functionally” or “communicatively,” the element may be coupled to the other element directly (e.g., by wire), wirelessly, or via a third element.

[0021] Terms such as “includes,” “comprising,” or “having” are intended to specify the presence of stated features, numbers, steps, operations, elements, components, or combinations thereof, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, elements, components, or combinations thereof.

[0022] It should also be understood that when an element is referred to as being “connected,” “coupled,” “supported,” or “contacting” another element, this includes not only the case where the elements are directly connected, coupled, supported, or contacted, but also the case where the elements are indirectly connected, coupled, supported, or contacted via a third element.

[0023] It will also be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present therebetween.

[0024] The induction heating cooker may include a coil substrate. A coil substrate having a double-layer coil pattern structure may be used as the coil substrate. In order to realize an induction heating cooker with high power (maximum 3kW or more) by using a coil substrate having a two-layer coil pattern structure, the thickness of copper in one layer (the thickness of the coil pattern) needs to be about 500μm. In this case, the influence of the skin effect may increase, which may increase the coil loss. In order to achieve high power while reducing the skin effect, a method may be considered: making the thickness and width of the coil pattern smaller and connecting multiple coil patterns in parallel to ensure current capacity. In this case, the number of interlayer connections for connecting multiple coil patterns in parallel may increase, and the coil loss may also increase according to the wiring length.

[0025] The present disclosure provides an induction heating cooker using a coil substrate having a multi-layer coil pattern structure, which can reduce coil loss while reducing the number of interlayer connections. Hereinafter, embodiments of the induction heating cooker according to the present disclosure will be described with reference to the accompanying drawings.

[0026] <Configuration of induction heating cooker>

[0027] Figure 1 1 is a schematic diagram of an induction heating cooker 100 according to an embodiment of the present disclosure. The induction heating cooker 100 according to an embodiment of the present disclosure inductively heats an object to be heated, for example, a cooking utensil such as a cooking pot, placed on a top plate. The induction heating cooker 100 according to an embodiment of the present disclosure can freely place and heat the object to be heated at any position on the top plate.

[0028] Reference Figure 1The induction heating cooker 100 according to an embodiment of the present disclosure may include a top plate 1 on which an object to be heated is placed, a plurality of heating coils 2 for heating the object to be heated, an inverter circuit 3 for supplying an alternating current to the heating coils 2, and a processor 41 for controlling the inverter circuit 3. Although not shown in the drawings, the induction heating cooker 100 may include a sensor coil for detecting the position of the object to be heated.

[0029] A flat mounting surface on which the object to be heated is placed is provided on the outer surface of the top plate 1. For example, the top plate 1 may be a flat plate formed of an electrically insulating material such as glass or ceramic.

[0030] The heating coil 2 is mounted on the rear surface of the top plate 1. Figure 1 , the plurality of heating coils 2 may be arranged to form a two-dimensional array type (vertical and horizontal matrix type) in a plan view.

[0031] The heating coils 2 can be mounted on a sheet substrate. For example, the plurality of heating coils 2 can be a printed circuit board (see Figure 2 The coil substrate 20 is formed by a patterning process such as a photoresist on a substrate. In an embodiment, the plurality of heating coils 2 may have the same shape and size. The shapes and sizes of the plurality of heating coils 2 do not have to be all the same. For example, at least one of the shapes and sizes of at least one of the plurality of heating coils 2 may be different from at least one of the shapes and sizes of the other heating coils. The specific configuration of the coil substrate 20 will be described below.

[0032] The inverter circuit 3 converts an AC voltage supplied from a power source (not shown) into an arbitrary driving frequency and outputs the arbitrary driving frequency to the heating coil 2. For example, the inverter circuit 3 may be a half-bridge inverter circuit using switching elements, or may be a full-bridge inverter circuit.

[0033] The control device 4 may include a processor 41 such as a central processing unit (CPU) and a memory 42. The control device 4 may further include an input unit. The processor 41 reads and executes a program stored in the memory 42. Thus, the processor 41 controls the inverter circuit 3 according to the program stored in the memory 42.

[0034] In an embodiment, the processor 41 may control the inverter circuit 3 to selectively supply power only to the heating coils 2 located below or near the object to be heated placed on the top plate 1 among the plurality of heating coils 2. The position of the object to be heated placed on the top plate 1 may be detected by a position sensor (such as an inductive proximity coil) mounted on the rear surface of the top plate 1. The processor 41 may control the power supplied to each heating coil 2 based on a detection value of a current sensor (not shown) mounted corresponding to each heating coil 2 in the inverter circuit 3.

[0035] <Coil Substrate 20>

[0036] Figure 2 2 is a plan view schematically showing the coil substrate 20 according to the embodiment of the present disclosure. Figure 3 2 is a cross-sectional view schematically showing a coil substrate 20 having a 16-layer structure according to an embodiment of the present disclosure. Figure 2 and Figure 3 The coil substrate 20 may be a printed circuit board formed by stacking six or more pattern layers PL, on which the coil pattern CP is formed. Insulating material is inserted between the pattern layers PL. According to the induction heating cooker 100 having the coil substrate 20, because the coil substrate 20 has a stacked structure including six or more layers, the thickness of one layer of the heating coil, such as the copper layer, can be reduced, thereby reducing the influence of surface effects and reducing coil loss.

[0037] In the coil substrate 20, a coil pattern CP is formed in each pattern layer. For example, the coil pattern CP may be spiral-shaped. In an embodiment, the coil pattern CP may be formed by a plurality of coil elements approximately rectangular in a plan view, such as Figure 2As shown. In an embodiment, the coil pattern CP can be formed by a plurality of coil elements that are circular in plan view. The shape of the coil elements forming the coil pattern CP is not limited to the above-mentioned shape. The coil substrate 20 can have a plurality of series pattern groups. The plurality of series pattern groups can be connected in parallel to each other. Each of the plurality of series pattern groups can have a plurality of coil patterns CP connected in series. The plurality of series pattern groups can be formed so that the coil patterns formed in adjacent pattern layers in the plurality of pattern layers are connected in parallel to each other. Therefore, the coils formed in the plurality of pattern layers can form a parallel connection relationship and a larger current capacity can be ensured. The plurality of coil patterns CP forming each of the plurality of series pattern groups can be formed in four or more pattern layers. At least one of the plurality of series pattern groups can have a plurality of pattern layer combinations that are different from the remaining series pattern groups. Therefore, the wiring structure can be simplified, thereby reducing the number of interlayer connections and thus reducing power loss. That is, by reducing the impedance gap between the parallel-connected series pattern groups due to the mutual impedance in each pattern layer, it is possible to theoretically maintain the same efficiency characteristics as the full-layer series connection structure. Furthermore, by reducing the number of interlayer connections and lowering interlayer wiring resistance compared to a full-layer series connection structure, a low-loss design can be achieved compared to a full-layer series connection structure. The multiple series pattern groups can include at least two series pattern groups having the same multiple pattern layer combinations. Thus, the number of interlayer connections can be reduced.

[0038] In an embodiment, Figure 2 and Figure 3 A coil substrate 20 is schematically shown, formed by stacking 16 pattern layers (the first to sixteenth layers). In the embodiment, the coil substrate 20 has four series pattern groups 21 to 24. Each of the four series pattern groups 21 to 24 has four coil patterns CP connected in series. The four series pattern groups 21 to 24 are connected in parallel to each other. The difference in the sum of the lengths of the coil patterns CP forming each of the multiple series pattern groups 21 to 24 can be 10% or less.

[0039] For example, reference Figure 3 , a series pattern group 21 is formed by connecting in series the coil patterns CP formed in the first, eighth, ninth, and sixteenth layers. A series pattern group 22 is formed by connecting in series the coil patterns CP formed in the second, seventh, tenth, and fifteenth layers. A series pattern group 23 is formed by connecting in series the coil patterns CP formed in the third, sixth, eleventh, and fourteenth layers. A series pattern group 24 is formed by connecting in series the coil patterns CP formed in the fourth, fifth, twelfth, and thirteenth layers.

[0040] In this way, Figure 2 and Figure 3The series pattern groups 21 to 24 shown in FIG. 2 have different pattern layer combinations that form the coil patterns CP connected in series. When the four series pattern groups 21 to 24 are connected in parallel, the coil patterns CP formed in different pattern layers are connected in parallel.

[0041] In addition, if Figure 2 As shown, in the coil substrate 20, two terminals (input terminal 2a and output terminal 2b) for connecting a plurality of series pattern groups 21 to 24 in parallel are formed on the outer periphery of the coil pattern CP. Figure 3 As shown, electrical connections between pattern layers are formed by conductors (through holes TH) formed by penetrating the coil substrate 20. The through holes TH are formed by penetrating all pattern layers PL. The four coil patterns CP forming each of the series pattern groups 21 to 24 are connected in series via one intermediate terminal 2c formed by a conductor mounted on the outer periphery of the coil pattern CP and a plurality of connection terminals 2d formed by a conductor mounted on the inner periphery of the coil pattern CP.

[0042] Furthermore, in the coil substrate 20 of this embodiment, the coil pattern CP is connected so that the input terminal 2a side is the uppermost layer of the multiple pattern layers PL, while the output terminal 2b side is the lowermost layer of the multiple pattern layers PL. This configuration makes it easier to form a thin-film structure for a weak current sensor by attaching it to the upper layer when forming multiple layers of the coil pattern CP.

[0043] The multi-layer structure of the coil substrate 20 is not limited to the above-mentioned 16-layer structure. Figure 4 is a plan view schematically illustrating coil patterns of a first layer and a second layer of a coil substrate having a 6-layer structure according to an embodiment of the present disclosure. Figure 5 is a schematic diagram illustrating an example of wiring of a coil substrate having a 6-layer structure according to an embodiment of the present disclosure.

[0044] Reference Figure 4 and Figure 5 , the coil substrate 20 is a printed circuit board formed by stacking six pattern layers. In the coil substrate 20, each pattern layer includes a spiral or concentric coil pattern CP. Figure 4 and Figure 5, the coil pattern CP of the first layer includes two spiral coil patterns CP11 and CP12 connected in parallel. The coil pattern CP of the second layer includes two spiral coil patterns CP21 and CP22 connected in series. The coil pattern CP of the third layer includes two independent spiral coil patterns CP31 and CP32. Therefore, the coil patterns CP31 and CP32 are connected in parallel to each other. The coil pattern CP of the fourth layer has the same structure as the coil pattern CP of the third layer. The coil pattern CP of the fourth layer includes two independent spiral coil patterns CP41 and CP42. Therefore, the coil patterns CP41 and CP42 are connected in parallel to each other. The coil pattern CP of the fifth layer has the same structure as the coil pattern CP of the second layer. That is, the coil pattern CP of the fifth layer includes two spiral coil patterns CP51 and CP52 connected in series. The coil pattern CP of the sixth layer has the same structure as the coil pattern CP of the first layer. That is, the coil pattern CP of the sixth layer includes two spiral coil patterns CP61 and CP62 connected in parallel.

[0045] The coil substrate 20 includes three series pattern groups 21 to 23, each of which includes four coil patterns CP connected in series. Specifically, the series pattern group 21 includes coil patterns CP11, CP32, CP41, and CP62 connected in series. The series pattern group 22 includes coil patterns CP12, CP31, CP42, and CP61 connected in series. The series pattern group 23 includes coil patterns CP21, CP22, CP52, and CP51 connected in series. The three series pattern groups 21 to 23 are connected in parallel. In this case, the difference in the sum of the lengths of the coil patterns CP forming each of the multiple series pattern groups 21 to 23 can be 10% or less.

[0046] In the three series pattern groups 21 to 23, two series pattern groups 21 and 22 are each formed by connecting in series four coil patterns CP formed in four pattern layers. That is, series pattern group 21 is formed by connecting in series four coil patterns CP11, CP32, CP41, and CP62 formed in the first, third, fourth, and sixth layers, respectively, while series pattern group 22 is formed by connecting in series four coil patterns CP12, CP31, CP42, and CP61 formed in the first, third, fourth, and sixth layers, respectively. Therefore, series pattern groups 21 and 22 have the same pattern layer combination that forms the series-connected coil patterns CP. Furthermore, series pattern group 23 is formed by connecting in series four coil patterns CP formed in two pattern layers. That is, series pattern group 23 is formed by connecting in series coil patterns CP21 and CP22 formed in the second layer to coil patterns CP52 and CP51 formed in the fifth layer. Therefore, the pattern layer combination that forms the series-connected coil patterns CP in series pattern group 23 differs from the pattern layer combination in the two series pattern groups 21 and 22. According to this configuration, when the three series pattern groups 21 to 23 are connected in parallel, a structure is formed in which the coil patterns CP formed in different pattern layers are connected in parallel.

[0047] In the coil substrate 20, two terminals (input terminal 2a and output terminal 2b) are formed on the outer periphery of the coil pattern CP, connecting the multiple series pattern groups 21 to 23 in parallel. Furthermore, electrical connections are established between the pattern layers using conductors (through holes TH) formed through all of the pattern layers. The coil patterns CP that form each series pattern group 21 to 23 are connected in series via connection terminals 2c formed by conductors mounted on the outer periphery of the coil pattern CP and connection terminals 2d formed by conductors mounted on the inner periphery of the coil pattern CP.

[0048] Here, it is assumed that the impedance of each of the outer patterns CP11, CP21, CP31, CP41, CP51, and CP61 is Z1, and the impedance of each of the inner patterns CP12, CP22, CP32, CP42, CP52, and CP62 is Z2. In this case, the impedance of the series pattern group 21 of the first, third, fourth, and sixth layers connected in series is: Z1 (outer pattern CP11 in the first layer) + Z2 (inner pattern CP32 in the third layer) + Z1 (outer pattern CP41 in the fourth layer) + Z2 (inner pattern CP62 in the sixth layer), that is, 2×Z1+2×Z2. Furthermore, the impedance of the series pattern group 22 of the first, third, fourth, and sixth layers connected in series is: Z2 (inner pattern CP12 in the first layer) + Z1 (outer pattern CP31 in the third layer) + Z2 (inner pattern CP42 in the fourth layer) + Z1 (outer pattern CP61 in the sixth layer), that is, 2×Z1+2×Z2. In addition, the impedance of the series pattern group 23 in which the second and fifth layers are connected in series is: Z1 (external pattern CP21 in the second layer) + Z2 (internal pattern CP22 in the second layer) + Z2 (internal pattern CP52 in the fifth layer) + Z1 (external pattern CP51 in the fifth layer), that is, 2×Z1+2×Z2.

[0049] Therefore, the impedances of the three series pattern groups 21 to 23 are calculated to be the same. According to this configuration, the current gap between the plurality of series pattern groups can be reduced by reducing the impedance gap between the plurality of series pattern groups, and thus the coil loss can be reduced. Figure 5 The number of interlayer connections in the coil substrate 20 shown is seven.

[0050] Figure 6A and Figure 6B Schematic diagram showing an example of wiring of a coil substrate having a 6-layer structure according to an embodiment of the present disclosure. Figure 6A , because the impedance gap between the three series pattern groups 21 to 23 can be reduced, the middle terminals of the series pattern groups 21 and 22 can be integrated when the impedances of the outer patterns CP11, CP21, CP31, CP41, CP51 and CP61 are all the same as Z1 and the impedances of the inner patterns CP12, CP22, CP32, CP42, CP52 and CP62 are all the same as Z2.

[0051] When the impedances of the outer patterns CP11, CP21, CP31, CP41, CP51, and CP61 are different, and the impedances of the inner patterns CP12, CP22, CP32, CP42, CP52, and CP62 are different, the middle terminals of the series pattern groups 21 and 22 need to be set separately. Figure 6B, when the impedance of each of the external patterns CP11, CP21 and CP31 is Z1, the impedance of each of the external patterns CP41, CP51 and CP61 is Z3, the impedance of each of the internal patterns CP12, CP22 and CP32 is Z2, the impedance of each of the internal patterns CP42, CP52 and CP62 is Z4, and Z1≠Z2≠Z3≠Z4, the middle terminals of the series pattern groups 21 and 22 need to be set separately.

[0052] Figure 7 : is a schematic diagram showing an example of wiring of a coil substrate having a 12-layer structure according to an embodiment of the present disclosure. Figure 7 The coil substrate 20 is a printed circuit board formed by stacking 12 pattern layers. Each pattern layer in the coil substrate 20 includes a spiral or concentric coil pattern CP. The coil pattern CP includes two coil patterns CP1 and CP2, and their impedance values are Z1 and Z2, respectively. The coil patterns CP of the first to third layers and the tenth to twelfth layers each have a structure in which two spiral coil patterns CP1 and CP2 are connected in parallel. The coil patterns CP of the fourth to ninth layers each include two independent spiral coil patterns CP1 and CP2.

[0053] The coil substrate 20 includes six series pattern groups 21 to 26. Each of the six series pattern groups 21 to 26 includes two coil patterns CP1 and two coil patterns CP2 connected in series. The six series pattern groups 21 to 26 are connected in parallel. In this case, the difference in the total length of the coil patterns constituting each of the plurality of series pattern groups 21 to 26 can be 10% or less.

[0054] For example, among the six series pattern groups 21 to 26, two series pattern groups 21 and 22 are each formed by connecting in series the two coil patterns CP1 and the two coil patterns CP2 formed in the first, sixth, seventh, and twelfth layers. Furthermore, two series pattern groups 23 and 24 are each formed by connecting in series the two coil patterns CP1 and the two coil patterns CP2 formed in the second, fifth, eighth, and eleventh layers. Furthermore, two series pattern groups 25 and 26 are formed by connecting in series the two coil patterns CP1 and the two coil patterns CP2 formed in the third, fourth, ninth, and tenth layers.

[0055] Furthermore, in the coil substrate 20, two terminals (input terminal 2a and output terminal 2b) are formed on the outer peripheries of the coil patterns CP1 and CP2, connecting the plurality of series pattern groups 21 to 26 in parallel. Electrical connections are formed between the pattern layers PL by conductors formed by penetrating all of the pattern layers. For example, the two coil patterns CP1 and the two coil patterns CP2 that form each of the series pattern groups 21 to 26 are connected in series via connection terminals 2c formed by conductors (through holes TH) mounted on the outer peripheries of the coil patterns CP1 and CP2, and connection terminals 2d formed by conductors mounted on the inner peripheries of the coil patterns CP1 and CP2.

[0056] According to this configuration, since the impedance of the six series pattern groups 21 to 26 is calculated as 2×Z1+2×Z2, the impedance gap can be designed to be small, thereby reducing coil loss. Figure 7 The number of interlayer connections in the illustrated coil substrate 20 is eighteen.

[0057] Figure 8 is a schematic diagram illustrating an example of wiring of a coil substrate having a 12-layer structure according to an embodiment of the present disclosure. Figure 8 The coil substrate 20 shown in FIG is a printed circuit board formed by stacking 12 pattern layers, similar to Figure 7 The coil substrate 20 shown in FIG, but the method of connecting the pattern layer is different from Figure 7 In the method. Figure 7 In the coil substrate 20 shown, the pattern layers are connected symmetrically with respect to the center of the pattern layer (between the sixth layer and the seventh layer), but Figure 8 In the coil substrate 20 shown, the pattern layers are connected asymmetrically with respect to the center of the pattern layers (between the sixth layer and the seventh layer).

[0058] Reference Figure 8 , when forming the series pattern groups 21 to 26, the coil pattern CP formed in the uppermost pattern layer is connected in series to the coil patterns CP formed in the pattern layers other than the lowermost layer. When forming the series pattern groups 21 to 26, the coil pattern CP close to the uppermost pattern layer is connected in series to the coil pattern CP formed in the pattern layer far from the lowermost pattern layer.

[0059] In the embodiment, two series pattern groups 21 and 22 are formed by connecting in series two coil patterns CP1 and two coil patterns CP2 formed in the first, sixth, ninth, and tenth layers. Furthermore, two series pattern groups 23 and 24 are each formed by connecting in series two coil patterns CP1 and two coil patterns CP2 formed in the second, fifth, eighth, and eleventh layers. Furthermore, two series pattern groups 25 and 26 are each formed by connecting in series two coil patterns CP1 and two coil patterns CP2 formed in the third, fourth, seventh, and twelfth layers.

[0060] Figure 9 Yes Display Figure 7 and Figure 8 The experimental results of coil loss in the wiring example of the coil substrate 20 having a 12-layer structure are shown. Figure 9 , even when the magnetic impedances of the series pattern groups 21 to 26 are designed to be the same, in actual driving, the influence of the mutual impedance on the surface layer side (for example, the first and twelfth layers in the case of a 12-layer structure) is particularly reduced, and the current flowing therein increases, so the coil loss increases. When coil patterns with smaller mutual impedance influences are connected in series, the impedance gap due to the proximity effect of multiple series pattern groups connected in parallel may increase. Therefore, in order to reduce the impedance gap caused by the proximity effect of multiple series pattern groups connected in parallel, it is better not to connect coil patterns with smaller mutual impedance influences in series, such as Figure 8 In other words, wiring that connects coil patterns with a greater mutual impedance influence and coil patterns with a smaller mutual impedance influence in series helps reduce impedance gaps caused by the proximity effect of multiple series pattern groups connected in parallel. For example, multiple series pattern groups 21 to 26 can be formed so that the coil pattern formed in the uppermost pattern layer is connected in series to the coil patterns formed in pattern layers other than the lowermost layer.

[0061] Although not shown in the drawings, the number of pattern layers of the coil substrate 20 may not be 6, 12, or 16, but may be, for example, 10. In addition, the series pattern group may have a structure in which 5 or more coil patterns are connected in series.

[0062] The present disclosure provides a coil substrate having a multilayer coil pattern structure capable of reducing coil loss, and an induction heating cooker using the coil substrate. The present disclosure provides a coil substrate having a multilayer coil pattern structure capable of reducing the number of interlayer connections, and an induction heating cooker using the coil substrate. The present disclosure is not limited thereto.

[0063] An induction heating cooker according to one aspect of the present disclosure may include a top plate and a plurality of heating coils, wherein an object to be heated is placed on the top plate. The plurality of heating coils are used to heat the object to be heated. Each of the plurality of heating coils may include a coil substrate formed by stacking six or more pattern layers, each pattern layer having a coil pattern formed therein. The coil substrate may include a plurality of series pattern groups, each series pattern group including a plurality of coil patterns connected in series. The plurality of series pattern groups are connected in parallel. An inverter circuit supplies alternating current to the heating coils. A processor controls the inverter circuit. For a stacked structure of six or more layers, the thickness of copper in one layer can be reduced, and coil loss can be reduced by reducing the influence of the skin effect.

[0064] In an embodiment, at least one of the plurality of series pattern groups may be obtained by connecting in series the coil patterns formed in four or more pattern layers. Thus, the number of interlayer connections may be reduced.

[0065] In an embodiment, a plurality of series pattern groups may be formed such that coil patterns formed in adjacent pattern layers among a plurality of pattern layers are connected in parallel. Thus, the coils formed in the plurality of pattern layers may be connected in parallel and a large current capacity may be ensured.

[0066] In an embodiment, at least one of the plurality of series pattern groups may have a different combination of multiple pattern layers from the remaining series pattern groups. In an embodiment, the plurality of series pattern groups may include at least two series pattern groups having the same combination of multiple pattern layers. Thus, the number of interlayer connections can be reduced, and the loss caused by the interlayer connections can be reduced, thereby reducing the total loss.

[0067] In an embodiment, a plurality of series pattern groups may be formed such that the coil pattern formed in the uppermost layer is connected in series to the coil patterns formed in pattern layers other than the lowermost layer. Thus, the impedance gap caused by the proximity effect of the plurality of series pattern groups connected in parallel can be reduced.

[0068] In an embodiment, the difference between the total lengths of the plurality of coil patterns constituting each of the plurality of series pattern groups is 10% or less. As the difference between the total lengths of the coil patterns in the plurality of series pattern groups increases, the current gap between the plurality of parallel-connected series pattern groups may increase, and thus, the loss may increase. By setting the difference between the total lengths of the coil patterns in the plurality of series pattern groups to 10% or less, current balance can be achieved in AC currents in the kilohertz range or higher.

[0069] In an embodiment, two terminals connecting multiple series pattern groups in parallel can be formed on the outer periphery of the coil pattern. In an embodiment, the electrical connection between multiple pattern layers can be formed by a conductor formed by penetrating the multiple pattern layers. Therefore, the manufacturing cost of the coil substrate can be reduced.

[0070] In an embodiment, the coil pattern may have a spiral shape.

[0071] As described above, although the induction heating cooker of the present disclosure has been described using limited embodiments and drawings, the present disclosure is not limited to the above embodiments, and various modifications may be made without departing from the spirit of the present disclosure.

Claims

1. An induction heating cooker comprising: a top plate (1) on which an object to be heated is placed; A plurality of heating coils (1) configured to heat the object to be heated, each of the plurality of heating coils comprising a coil substrate (20) formed by stacking six or more pattern layers (PL), each of the plurality of pattern layers having a coil pattern (CP) formed therein, wherein the coil substrate comprises a plurality of series pattern groups (21 to 26), each of the plurality of series pattern groups comprising a plurality of coil patterns connected in series, and the plurality of series pattern groups being connected in parallel; an inverter circuit (3) configured to supply an alternating current to the heating coil; as well as A processor (41) is configured to control the inverter circuit.

2. The induction heating cooker according to claim 1, wherein At least one of the plurality of series pattern groups is obtained by connecting in series coil patterns formed in four or more pattern layers.

3. The induction heating cooker according to claim 1 or 2, wherein: The plurality of series pattern groups are formed such that coil patterns formed in adjacent pattern layers among the plurality of pattern layers are connected in parallel to each other.

4. The induction heating cooker according to any one of claims 1 to 3, wherein: At least one of the plurality of series pattern groups has a combination of a plurality of pattern layers different from the remaining series pattern groups.

5. The induction heating cooker according to any one of claims 1 to 4, wherein: The plurality of series pattern groups include at least two series pattern groups having the same combination of the plurality of pattern layers.

6. The induction heating cooker according to any one of claims 1 to 5, wherein: The plurality of series pattern groups are formed such that the coil pattern formed in the uppermost layer is connected in series to the coil patterns formed in the pattern layers except for the lowermost layer.

7. The induction heating cooker according to any one of claims 1 to 6, wherein: A difference between total lengths of the plurality of coil patterns constituting each of the plurality of series pattern groups is 10% or less.

8. The induction heating cooker according to any one of claims 1 to 7, wherein: Two terminals (2a, 2b) for connecting the plurality of series pattern groups in parallel are formed on the outer periphery of the coil pattern.

9. The induction heating cooker according to any one of claims 1 to 8, wherein: Electrical connections between the plurality of pattern layers are formed by conductors (TH) formed by penetrating the plurality of pattern layers.

10. The induction heating cooker according to any one of claims 1 to 9, wherein: The coil pattern has a spiral shape.

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