Cooking appliance

Abstract

A cooking appliance is disclosed. The cooking appliance according to at least one of various embodiments of the present disclosure may include: an upper plate part on which an object to be heated is placed; a plurality of working coils for heating the object to be heated; an inverter for applying a current to each of the working coils; and a controller for controlling the operation of the inverter so that the object to be heated is heated through each of the working coils. At least one of the working coils may be a PCB working coil including a plurality of turns, and an interval between the turns may not be uniform.

Description

Cooking appliances

[0001] The present disclosure relates to a cooking appliance. More specifically, the present disclosure relates to a cooking appliance including a working coil that maximizes heating efficiency and a cooking appliance that heats a heated object using a PCB working coil.

[0002] A variety of cooking appliances are used to heat food at home and in restaurants. While gas-fired ranges have traditionally been widely used, devices that use electricity instead of gas to heat objects, such as cooking vessels like pots, are becoming increasingly popular.

[0003] Methods for heating an object using electricity are broadly divided into resistance heating and induction heating. Resistance heating involves passing current through a metallic resistance wire or a non-metallic heating element such as silicon carbide, which then transfers the generated heat to the object (e.g., a cooking vessel) through radiation or conduction, thereby heating the object. Induction heating involves applying a certain amount of high-frequency power to a coil, which then utilizes the magnetic field generated around the coil to generate eddy currents in the object, which is made of metallic components, thereby heating the object itself.

[0004] Induction heating is mainly used in cooking appliances these days.

[0005] Additionally, research is currently underway to apply PCB working coils to cooking appliances. However, PCB working coils can generate significant heat, potentially compromising the stability of cooking appliances. Therefore, a solution is needed.

[0006] The present disclosure seeks to provide a cooking appliance including a working coil that maximizes heating efficiency through the arrangement of the working coil.

[0007] The present disclosure provides a cooking device that heats a heated object using a PCB (Printed Circuit Board) working coil.

[0008] The present disclosure is directed to providing an early device including a PCB working coil having various structures or patterns for reducing heat generation, which is a problem when operating at high frequencies.

[0009] A cooking appliance according to at least one of the various embodiments of the present disclosure may include: a top portion on which an object to be heated is placed; a plurality of working coils that heat the object to be heated; an inverter that applies current to each of the working coils; and a controller that controls the operation of the inverter so that the object to be heated is heated through each of the working coils. In this case, the at least one working coil is a PCB working coil including a plurality of turns, and the intervals between the turns may not be uniform.

[0010] In a cooking appliance according to at least one of the various embodiments of the present disclosure, the spacing between turns of the PCB working coil may increase as it gets closer to the center point of the PCB working coil.

[0011] In a cooking appliance according to at least one of the various embodiments of the present disclosure, the PCB working coil may be divided into a plurality of sections from a center point to the outermost section, and each section may include at least one turn.

[0012] In a cooking appliance according to at least one of the various embodiments of the present disclosure, the plurality of sections may include a first section in which the interval between turns does not change and a second section in which the interval between turns changes.

[0013] In a cooking appliance according to at least one of the various embodiments of the present disclosure, the first section may have a greater interval between turns than the second section.

[0014] In a cooking appliance according to at least one of the various embodiments of the present disclosure, the first section may be a section closer to the center point than the second section.

[0015] In a cooking appliance according to at least one of the various embodiments of the present disclosure, the width of each turn of the PCB working coil may not be uniform.

[0016] In a cooking appliance according to at least one of the various embodiments of the present disclosure, the width of each turn of the PCB working coil may be wider the closer it is to the center point.

[0017] In a cooking appliance according to at least one of the various embodiments of the present disclosure, each turn of the PCB working coil includes a plurality of unit coils, and the spacing between unit coils of the plurality of unit coils included in the turn may not be uniform depending on the position of the turn.

[0018] In a cooking appliance according to at least one of the various embodiments of the present disclosure, the closer the position of the turn is to the center point of the PCB working coil, the wider the gap between unit coils of the plurality of unit coils included in the turn.

[0019] In a cooking appliance according to at least one of the various embodiments of the present disclosure, each turn of the PCB working coil includes a plurality of unit coils, and the number of unit coils included in the turn may vary depending on the position of the turn.

[0020] In a cooking appliance according to at least one of the various embodiments of the present disclosure, the number of unit coils included in each turn of the PCB working coil may increase as it gets closer to the center point of the PCB working coil.

[0021] In a cooking appliance according to at least one of the various embodiments of the present disclosure, each turn of the PCB working coil includes a plurality of unit coils, and the width of each unit coil included in the turn may be different depending on the position of the turn.

[0022] In a cooking appliance according to at least one of the various embodiments of the present disclosure, the width of a unit coil included in each turn of the PCB working coil may be wider the closer it is to the center point of the PCB working coil.

[0023] In a cooking appliance according to at least one of the various embodiments of the present disclosure, the working coil includes a plurality of layers of PCB working coils, and the PCB working coils of each layer may differ from each other in at least one of a turn-to-turn spacing, a turn width, a turn-to-turn spacing, and a number of unit coils included in each turn.

[0024] According to at least one of the various embodiments of the present disclosure, there is an effect of maximizing the heat loss of a heated object, thereby maximizing the heating efficiency.

[0025] According to at least one of the various embodiments of the present disclosure, there is an effect of maximizing heating efficiency by controlling a concentrated heating area of ​​a heated object.

[0026] According to at least one of the various embodiments of the present disclosure, there is an effect of heating a heated object using a PCB (Printed Circuit Board) working coil in a cooking appliance.

[0027] According to at least one of the various embodiments of the present disclosure, there is an effect of ensuring stable operation of a cooking appliance by reducing heat generation, which is particularly problematic when operating at high frequencies, and at the same time preventing malfunctions of the cooking appliance that may occur due to heat generation.

[0028] FIG. 1 is a perspective view illustrating a cooking appliance according to an embodiment of the present disclosure.

[0029] FIG. 2 is a perspective view illustrating a cooking appliance and a cooking vessel according to an embodiment of the present disclosure.

[0030] FIG. 3 is a cross-sectional view of a cooking appliance and a cooking vessel according to an embodiment of the present disclosure.

[0031] Figure 4 is a circuit diagram of a cooking appliance according to an embodiment of the present disclosure.

[0032] FIG. 5 is a cross-sectional view illustrating a cooking appliance and a heated object according to an embodiment of the present disclosure.

[0033] FIG. 6 is a cross-sectional view illustrating a cooking appliance and a heated object according to another embodiment of the present disclosure.

[0034] FIG. 7 is a drawing showing the output characteristics of a cooking appliance according to an embodiment of the present disclosure.

[0035] Figure 8 is a drawing showing an example of a working coil.

[0036] Figures 9 and 10 are drawings for explaining the magnetic path length according to the magnetic path of each turn.

[0037] Figure 11 is a graph showing the magnetic path length of each turn of the working coil.

[0038] Figure 12 is a graph showing the current density of a heated object.

[0039] Fig. 13 is a drawing showing an example of the area-specific heat loss (EM-Loss) of a heated object heated by a uniform working coil.

[0040] FIG. 14 is a drawing illustrating the shape of a working coil according to the first embodiment of the present disclosure.

[0041] Figure 15 is a graph showing the magnetic path length of each turn of the working coil.

[0042] Figure 16 is a graph showing the current density of a heated object.

[0043] Fig. 17 is a drawing showing an example of the area-specific heat loss (EM-Loss) of a heated object heated by a reverse-type working coil.

[0044] FIG. 18 is a drawing illustrating the shape of a working coil according to a second embodiment of the present disclosure.

[0045] Figure 19 is a graph showing the magnetic path length of each turn of the working coil.

[0046] Figure 20 is a graph showing the current density of a heated object.

[0047] Fig. 21 is a drawing showing an example of the area-specific heat loss (EM-Loss) of a heated object heated by a forward-type working coil.

[0048] Figure 22 is a drawing illustrating a PCB working coil.

[0049] FIG. 23 is a drawing illustrating an interval between turns according to one embodiment of the present disclosure.

[0050] FIG. 24 is a drawing illustrating an interval between turns according to another embodiment of the present disclosure.

[0051] FIGS. 25 to 27 are drawings illustrating a PCB working coil in which turns are arranged according to embodiments of the present disclosure.

[0052] FIGS. 28 to 29 are drawings illustrating a PCB working coil in which turns are arranged according to embodiments of the present disclosure.

[0053] Fig. 30 is a drawing illustrating the internal configuration of a turn in the PCB working coil of Fig. 22.

[0054] Figures 31 to 34 are drawings illustrating unit coils constituting one layer of one turn of Figure 30.

[0055] Figures 35 and 36 are drawings illustrating the unit coil configuration for the multi-layer of Figure 30.

[0056] FIG. 37 is a drawing illustrating an interval between turns in oz according to one embodiment of the present disclosure.

[0057] FIG. 38 is a diagram illustrating a change in resistance versus the number of turns according to one embodiment of the present disclosure.

[0058] FIG. 39 is a drawing illustrating a case in which the number of twists is varied when changing from an inner turn to an outer turn according to one embodiment of the present disclosure.

[0059] Hereinafter, preferred embodiments according to the present disclosure will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0060] The suffixes "module" and "part" used for components in the following description are given or used interchangeably only for the convenience of writing specifications, and do not have distinct meanings or roles in themselves.

[0061] In the following description, “connected” between components includes not only direct connection of the components but also indirect connection through at least one other component, unless otherwise specified.

[0062] Hereinafter, a cooking appliance and its operating method according to an embodiment of the present disclosure will be described. In the present disclosure, the cooking appliance may be, but is not limited to, an induction heating cooktop.

[0063] FIG. 1 is a perspective view illustrating a cooking appliance according to an embodiment of the present disclosure.

[0064] Referring to FIG. 1, a cooking appliance (1) according to an embodiment of the present disclosure may include a case (25), a cover plate (20), and a working coil (WC). The cooking appliance (1) may further include an intermediate material (IM).

[0065] A working coil (WC) can be installed in the case (25).

[0066] In addition to the working coil (WC), various devices related to driving the working coil (WC) may be installed in the case (25). The various devices may include, for example, at least one of a power supply unit (110, see FIG. 4) that provides AC power, a rectifier unit (120, see FIG. 4) that rectifies the AC power of the power supply unit into DC power, an inverter unit (140, see FIG. 4) that converts the DC power rectified by the rectifier unit into a resonant current through a switching operation and supplies it to the working coil (WC), and a control module (not shown) that controls the operation of various devices in the cooking appliance (1).

[0067] The cover plate (20) is coupled to the top of the case (25), and may be provided with a top plate (15) on which a heated object (not shown), such as a cooking vessel, is placed.

[0068] The upper portion (15) may be made of a glass material, such as ceramic glass, for example, but this is merely an example. The material of the upper portion (15) according to the embodiment of the present disclosure may vary.

[0069] Additionally, the upper portion (15) may be equipped with an input interface (not shown) that transmits the user's input to a control module (not shown) for the input interface. The input interface may be equipped at a location other than the upper portion (15).

[0070] The input interface is a module for receiving user inputs such as a desired heating intensity or the operating time of the cooking appliance (1), and can be implemented with a physical button or a touch panel. The input interface may further include a power button, a lock button, a power level adjustment button (+,-), a timer adjustment button (+,-), a charging mode button, etc. The control module for the input interface can transmit user input to the aforementioned control module (e.g., a control module for an inverter). The aforementioned control module can control the operation of various devices (e.g., a working coil (WC)) based on the user input, and thus specific details thereof are omitted.

[0071] On the upper part (15), the driving status of the working coil (WC) and the heating intensity (i.e., the heating power) can be visually displayed in the shape of a fireball. The shape of the fireball can be displayed by an indicator (not shown) composed of a plurality of light-emitting elements (e.g., LEDs) provided within the case (25).

[0072] A working coil (WC) is installed inside the case (25) and can heat the object to be heated.

[0073] The working coil (WC) can be driven and controlled by the control module (not shown) described above. For example, when the heated object is placed on the upper plate (15), the working coil (WC) can be driven by the control module.

[0074] A working coil (WC) can not only directly heat a magnetic object to be heated (i.e., a magnetic substance), but can also indirectly heat a non-magnetic object to be heated (i.e., a non-magnetic substance) through an intermediate heating element (IM).

[0075] The working coil (WC) can heat the object to be heated by induction heating, and can be provided to overlap with the intermediate heating body (IM) in the longitudinal direction (i.e., vertically or vertically).

[0076] In Fig. 1, one working coil (WC) is illustrated as being installed in the case (25), but this is not limited thereto. That is, a plurality of working coils (WC) may be installed in the case (25). An intermediate heating element (IM) may be installed corresponding to the working coil (WC).

[0077] An intermediate heating element (IM) may be installed on the upper plate (15). The intermediate heating element (IM) may be coated on the upper plate (15) to heat a non-magnetic material among the objects to be heated. The intermediate heating element (IM) may be inductively heated by a working coil (WC).

[0078] The intermediate heating element (IM) may be formed on the upper or lower surface of the upper plate (15). For example, the intermediate heating element (IM) may be installed on the upper surface of the upper plate (15) as illustrated in FIG. 3, or may be installed on the lower surface of the upper plate (15) as illustrated in FIG. 4.

[0079] The intermediate heating element (IM) may be provided so as to overlap at least a portion of the working coil (WC) in the longitudinal direction (i.e., vertically or vertically). Therefore, the object to be heated can be heated regardless of the type or arrangement of the object to be heated through the working coil (WC) and the intermediate heating element (IM).

[0080] The intermediate material (IM) can have at least one of magnetic and non-magnetic properties (i.e., magnetic, non-magnetic, or both magnetic and non-magnetic).

[0081] The intermediate heating element (IM) may be formed of a conductive material, such as, but not limited to, aluminum (Al). In other words, the intermediate heating element (IM) may be formed of a material other than a conductive material.

[0082] In Fig. 1, an intermediate heating body (IM) having a shape in which multiple rings of different diameters are repeated is illustrated, but is not limited thereto and may have other shapes.

[0083] In FIGS. 1, 5 and 6, one intermediate heating body (IM) is illustrated, but there may be multiple intermediate heating bodies (IM).

[0084] Referring to FIG. 2, the cooking container can be positioned above the cooking device (1), and the cooking device (1) can heat the cooking container positioned above.

[0085] First, the method by which the cooking appliance (1) heats the cooking container is explained.

[0086] As illustrated in Fig. 2, the cooking appliance (1) can generate a magnetic field (22) so that at least a portion of the magnetic field passes through the cooking container. At this time, if the material of the cooking container contains an electrical resistance component, the magnetic field (22) can induce an eddy current (30) in the cooking container. This eddy current (30) generates heat in the cooking container itself, and this heat is conducted or radiated and transferred to the interior of the cooking container, so that the contents of the cooking container can be cooked.

[0087] Meanwhile, if the material of the cooking vessel does not contain an electrical resistance component, eddy current (30) does not occur. Therefore, in this case, the cooking appliance (1) cannot heat the cooking vessel.

[0088] Therefore, the cooking container that can be heated by this cooking appliance (1) may be a metal container such as a stainless steel container or an enamel or cast iron container.

[0089] Next, the method by which the cooking appliance (10) generates a magnetic field (22) is described.

[0090] As shown in Fig. 3, the cooking appliance (1) may include at least one of a top plate (15), a working coil (WC), and a ferrite core (45).

[0091] The upper portion (15) is capable of supporting a cooking container, on which a cooking container is placed. That is, the cooking container can be placed on the upper surface of the upper portion (15). A heating area in which the cooking container is heated can be formed in the upper portion (15).

[0092] And the top plate (15) can be formed of reinforced glass made of a ceramic material that synthesizes various minerals. Accordingly, the top plate (15) can protect the cooking appliance (1) from external impacts, etc.

[0093] In addition, the top plate (15) can prevent foreign substances such as dust from entering the inside of the cooking appliance (1).

[0094] A working coil (WC) may be located below the top plate (15). This working coil (WC) may or may not be supplied with current to generate a magnetic field (22). Specifically, current may or may not flow to the working coil (WC) depending on the on / off of the internal switching element of the cooking appliance (1).

[0095] When current flows through the working coil (WC), a magnetic field (22) is generated, and this magnetic field (22) can encounter the electrical resistance component contained in the cooking vessel to generate an eddy current (30). The eddy current (30) heats the cooking vessel, and thus the contents of the cooking vessel can be cooked.

[0096] Additionally, the heat output of the cooking device (1) can be adjusted depending on the amount of current flowing through the working coil (WC). For example, the more current flowing through the working coil (WC), the more a magnetic field (22) is generated, and accordingly, the magnetic field passing through the cooking vessel increases, so that the heat output of the cooking device (1) can be increased.

[0097] The ferrite core (45) is a component for protecting the internal circuit of the cooking appliance (1). Specifically, the ferrite core (45) acts as a shield to block the influence of the magnetic field (22) generated from the working coil (WC) or the electromagnetic field generated externally on the internal circuit of the cooking appliance (1).

[0098] For this purpose, the ferrite core (45) can be formed of a material having a very high permeability. The ferrite core (45) serves to guide the magnetic field flowing into the interior of the cooking device (1) so that it does not radiate but flows through the ferrite core (45). The movement of the magnetic field (22) generated in the working coil (WC) by the ferrite core (45) can be as illustrated in Fig. 2.

[0099] Meanwhile, the cooking appliance (1) may further include other components in addition to the above-described top plate (15), working coil (WC), and ferrite core (45). For example, the cooking appliance (1) may further include an insulating material (not shown) positioned between the top plate (15) and the working coil (WC). That is, the cooking appliance according to the present disclosure is not limited to the cooking appliance (1) illustrated in FIG. 3.

[0100] FIG. 4 is a diagram showing a circuit diagram of a cooking appliance (1) according to an embodiment of the present disclosure.

[0101] Referring to FIG. 4, the cooking appliance (1) may include some or all of a power supply unit (110), a rectifier unit (120), a DC link capacitor (130), an inverter unit (140), a working coil (WC), and a resonance capacitor (160).

[0102] The power supply unit (110) can receive an external power source, for example, AC (Alternating Current) power, and supply it to the rectifier unit (120).

[0103] The rectifier (120) is an electrical device that converts alternating current into direct current, and can convert the alternating current voltage supplied through the power supply (110) into direct current voltage and supply the converted voltage to both DC terminals (121).

[0104] The output terminal of the rectifier (120) can be connected to both DC terminals (121). The DC terminals (121) can be referred to as a 'DC link'. The voltage measured at both DC terminals (121) is referred to as the 'DC link voltage'.

[0105] The DC link capacitor (130) acts as a buffer between the power supply unit (110) and the inverter unit (140). Specifically, the DC link capacitor (130) can maintain the DC link voltage converted through the rectifier unit (120) and supply it to the inverter unit (140).

[0106] The inverter unit (140) can switch the voltage applied to the working coil (WC) so that a high-frequency current flows in the working coil (WC). The inverter unit (140) can apply a current to the working coil (WC). The inverter unit (140) can include a relay or a semiconductor switch that turns on or off the working coil (WC). For example, the semiconductor switch can include an IGBT (Insulated Gate Bipolar Transistor) or a WBG (Wide Band GaN) element. The WBG element can include SiC (Silicon Carbide) or GaN (Gallium Nitride). The inverter unit (140) drives the semiconductor switch so that a high-frequency current flows in the working coil (WC), and accordingly, a high-frequency magnetic field is formed in the working coil (WC).

[0107] The working coil (WC) may include at least one working coil (WC) that generates a magnetic field for heating a heated object (HO). The working coil (WC) may or may not have current flowing through it depending on whether a switching element is driven. When current flows through the working coil (WC), a magnetic field is generated. The working coil (WC) may generate a magnetic field according to the current flowing through it, thereby heating the cooking device (1).

[0108] One side of the working coil (WC) is connected to a connection point of a switching element of an inverter unit (140), and the other side can be connected to a resonant capacitor (160).

[0109] The driving of the switching element is performed by a driving unit (not shown), and the switching elements are operated alternately by controlling the switching time output from the driving unit, so that a high-frequency voltage can be applied to the working coil (WC). Since the on / off time of the switching element applied from the driving unit (not shown) is controlled in a gradually compensated manner, the voltage supplied to the working coil (WC) can change from a low voltage to a high voltage.

[0110] The resonant capacitor (160) can resonate with the working coil (WC).

[0111] The resonant capacitor (160) may be a component that acts as a buffer. The resonant capacitor (160) controls the rate of increase in saturation voltage during the turn-off of the switching element, thereby affecting energy loss during the turn-off time.

[0112] FIG. 5 is a cross-sectional view illustrating a cooking appliance (1) and a heated object (HO) according to an embodiment of the present disclosure.

[0113] FIG. 6 is a cross-sectional view illustrating a cooking appliance (1) and a heated object (HO) according to another embodiment of the present disclosure.

[0114] Referring to FIGS. 5 and 6, a cooking appliance (1) according to one embodiment of the present disclosure may further include at least some or all of an insulating material (35), a shielding plate (45), a support member (50), and a cooling fan (55).

[0115] Insulation (35) may be provided between the upper part (15) and the working coil (WC).

[0116] Specifically, the insulation (35) can be mounted under the upper part (15), and a working coil (WC) can be placed under it.

[0117] This insulation material (35) can block the heat generated when the intermediate heating element (IM) or the heated object (HO) is heated by the driving of the working coil (WC) from being transferred to the working coil (WC).

[0118] That is, when the intermediate heating body (IM) or the heated object (HO) is heated by the electromagnetic induction of the working coil (WC), the heat of the intermediate heating body (IM) or the heated object (HO) is transferred to the upper plate (15), and the heat of the upper plate (15) is transferred back to the working coil (WC), which may damage the working coil (WC).

[0119] In this way, the insulation material (35) can prevent the working coil (WC) from being damaged by heat by blocking the heat transferred to the working coil (WC), and further prevent the heating performance of the working coil (WC) from being deteriorated.

[0120] Note that although not an essential component, a spacer (not shown) may be installed between the working coil (WC) and the insulation (35).

[0121] Specifically, a spacer (not shown) can be inserted between the working coil (WC) and the insulation (35) to prevent direct contact between the working coil (WC) and the insulation (35). Accordingly, the spacer (not shown) can block heat generated when the intermediate heating element (IM) or the heated object (HO) is heated by the driving of the working coil (WC) from being transferred to the working coil (WC) through the insulation (35).

[0122] That is, the spacer (not shown) can partially share the role of the insulation (35), so that the thickness of the insulation (35) can be minimized, and thereby the gap between the heated object (HO) and the working coil (WC) can be minimized.

[0123] In addition, a plurality of spacers (not shown) may be provided, and the plurality of spacers may be arranged to be spaced apart from each other between the working coil (WC) and the insulation (35). Accordingly, air sucked into the case (25) by the cooling fan (55) described later may be guided to the working coil (WC) by the spacers (not shown).

[0124] That is, the spacer (not shown) can improve the cooling efficiency of the working coil (WC) by guiding the air introduced into the case (25) by the cooling fan (55) to be properly delivered to the working coil (WC).

[0125] A shielding plate (45) is mounted below the working coil (WC) to block a magnetic field generated downward when the working coil (WC) is driven. The shielding plate (45) may be ferrite.

[0126] Specifically, the shielding plate (45) can block the magnetic field generated downward when the working coil (WC) is driven, and can be supported upward by the support member (50).

[0127] The support member (50) is installed between the lower surface of the shielding plate (45) and the lower plate of the case (25) to support the shielding plate (45) upward.

[0128] Specifically, the support member (50) can indirectly support the insulating material (35) and the working coil (WC) upward by supporting the shielding plate (45) upward, thereby allowing the insulating material (35) to be in close contact with the upper plate (15).

[0129] As a result, the gap between the working coil (WC) and the heated object (HO) can be maintained constant.

[0130] For reference, the support member (50) may include, but is not limited to, an elastic body (e.g., a spring) for supporting the shield plate (45) upward, for example. In addition, the support member (50) is not an essential component and may be omitted from the cooking appliance (1).

[0131] A cooling fan (55) can be installed inside the case (25) to cool the working coil (WC).

[0132] Specifically, the cooling fan (55) can be driven and controlled by the aforementioned control module and can be installed on the side wall of the case (25). Of course, the cooling fan (55) can be installed in a location other than the side wall of the case (25), but for the convenience of explanation, in the embodiment of the present disclosure, it will be described as an example in which the cooling fan (55) is installed on the side wall of the case (25).

[0133] In addition, the cooling fan (55) can suck in air outside the case (25) and transfer it to the working coil (WC), as shown in FIGS. 5 and 6, or suck in air (especially, heat) inside the case (25) and discharge it outside the case (25).

[0134] Through this, efficient cooling of components (particularly, working coil (WC)) inside the case (25) is possible.

[0135] In addition, as described above, the air outside the case (25) delivered to the working coil (WC) by the cooling fan (55) can be guided to the working coil (WC) by the spacer. Accordingly, direct and efficient cooling of the working coil (WC) is enabled, thereby improving the durability of the working coil (WC) (i.e., improving durability by preventing heat damage).

[0136] The intermediate heating element (IM) may be a material having a resistance value that can be heated by the working coil (WC).

[0137] The thickness of the intermediate heating body (IM) may be inversely proportional to the resistance value (i.e., surface resistance value) of the intermediate heating body (IM). That is, the thinner the thickness of the intermediate heating body (IM), the higher the resistance value (i.e., surface resistance value) of the intermediate heating body (IM). Therefore, the intermediate heating body (IM) may be changed in characteristics into a heatable load by being installed thinly on the upper plate (15).

[0138] For reference, the intermediate heating body (IM) according to the embodiments of FIGS. 5 and 6 may have a thickness of, for example, 0.1 um to 1,000 um, but is not limited thereto.

[0139] An intermediate heating element (IM) having such characteristics exists to heat a non-magnetic material, and the impedance characteristics between the intermediate heating element (IM) and the heated object (HO) can change depending on whether the heated object (HO) placed on the upper plate (15) is a magnetic material or a non-magnetic material.

[0140] The following explains the case where the heated object (HO) is a magnetic substance.

[0141] The resistance component (R1) and the inductor component (L1) of the heated object (HO) form an equivalent circuit with the resistance component (R2) and the inductor component (L2) of the intermediate heating body (IM), and at this time, the impedance of the magnetic heated object (HO) (i.e., the impedance composed of R1 and L1) may be smaller than the impedance of the intermediate heating body (IM) (i.e., the impedance composed of R2 and L2). Accordingly, the magnitude of the eddy current (I1) applied to the magnetic heated object (HO) may be larger than the magnitude of the eddy current (I2) applied to the intermediate heating body (IM). Accordingly, most of the eddy current generated by the working coil (WC) is applied to the heated object (HO), so that the heated object (HO) can be heated. That is, when the object to be heated (HO) is a magnetic substance, the above-mentioned equivalent circuit is formed and most of the eddy current is applied to the object to be heated (HO), so the working coil (WC) can directly heat the object to be heated (HO).

[0142] Next, the case where the heated object is non-magnetic is explained as follows.

[0143] When a non-magnetic heated object (HO) is placed on the upper plate (15) and a working coil (WC) is driven, there may be no impedance in the non-magnetic heated object (HO), while an impedance may exist in the intermediate heated object (IM). That is, a resistance component (R) and an inductor component (L) may exist only in the intermediate heated object (IM). Accordingly, when a non-magnetic heated object (HO) is placed on the upper plate (15) and a working coil (WC) is driven, the resistance component (R) and the inductor component (L) of the intermediate heated object (IM) may form an equivalent circuit. Accordingly, an eddy current (I) may be applied only to the intermediate heated object (IM), while no eddy current may be applied to the non-magnetic heated object (HO). More specifically, the eddy current (I) generated by the working coil (WC) is applied only to the intermediate heating body (IM), so that the intermediate heating body (IM) can be heated. That is, when the heated object (HO) is a non-magnetic body, the eddy current (I) is applied to the intermediate heating body (IM), so that the intermediate heating body (IM) is heated, and the non-magnetic heated object (HO) can be indirectly heated by the intermediate heating body (IM) heated by the working coil (WC). In this case, the intermediate heating body (IM) can be the main heating source.

[0144] To summarize, regardless of whether the object to be heated (HO) is magnetic or non-magnetic, the object to be heated (HO) can be heated directly or indirectly by a single heat source called a working coil (WC). That is, if the object to be heated (HO) is magnetic, the working coil (WC) directly heats the object to be heated (HO), and if the object to be heated (HO) is non-magnetic, the intermediate heating element (IM) heated by the working coil (WC) can indirectly heat the object to be heated (HO).

[0145] Next, FIG. 7 is a drawing showing the output characteristics of a cooking appliance according to an embodiment of the present disclosure.

[0146] First, the Q factor (quality factor) may be a value indicating the sharpness of resonance in a resonant circuit. Therefore, in the case of a cooking appliance (1), the Q factor is determined by the inductance value of the working coil (WC) included in the cooking appliance (1) and the capacitance value of the resonant capacitor (160). The resonance curve is different depending on the Q factor. Therefore, the cooking appliance (1) has different output characteristics depending on the inductance value of the working coil (WC) and the capacitance value of the resonant capacitor (160).

[0147] Figure 7 shows an example of a resonance curve according to the Q factor. Generally, the larger the Q factor, the sharper the curve, and the smaller the Q factor, the broader the curve.

[0148] The horizontal axis of the resonance curve represents frequency, and the vertical axis represents the output power. The frequency at which maximum power is output on the resonance curve is called the resonance frequency (f0).

[0149] In general, the cooking appliance (1) uses a frequency in the right region based on the resonant frequency (f0) of the resonance curve. In addition, the cooking appliance (1) may have a minimum and maximum operating frequency that can be operated set in advance.

[0150] For example, the cooking appliance (1) has a maximum operating frequency (f max ) to the minimum operating frequency (f min ) can operate at a frequency corresponding to the range of the cooking device (1). That is, the operating frequency range of the cooking device (1) is the maximum operating frequency (f max ) to the minimum operating frequency (f min ) may be up to.

[0151] For example, the maximum operating frequency (f max) may be the maximum switching frequency of the IGBT. The maximum switching frequency of the IGBT may refer to the maximum frequency that can be driven, taking into account the withstand voltage and capacity of the IGBT switching element. For example, the maximum operating frequency (f max ) can be 75kHz.

[0152] Minimum operating frequency (f min ) can be about 20 kHz. In this case, since the cooking appliance (1) does not operate at an audible frequency (about 16 Hz to 20 kHz), there is an effect of reducing the noise of the cooking appliance (1).

[0153] Meanwhile, the maximum operating frequency (f) described above max ) and minimum operating frequency (f min ) are only examples and are not limited thereto.

[0154] When receiving a heating command, the cooking appliance (1) can determine an operating frequency according to a heat power level set in the heating command. Specifically, the cooking appliance (1) can adjust the output power by lowering the operating frequency as the set heat power level increases, and by raising the operating frequency as the set heat power level decreases. That is, when receiving a heating command, the cooking appliance (1) can perform a heating mode in which it operates in any one of the operating frequency ranges according to the set heat power.

[0155] In the following description, the cooking vessel may be a heated object (HO).

[0156] Figure 8 is a drawing showing an example of a working coil.

[0157] A working coil (WC) may be formed by a plurality of turns (T). For example, the working coil (WC) may be formed by ten turns (T). The plurality of turns (T) may include first to tenth turns (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10). However, this is merely an example, and the number of turns (T) forming the working coil (WC) is not limited thereto.

[0158] The first turn (T1) may be the turn closest to the center of the working coil (WC) among the ten turns (T). Additionally, the tenth turn (T10) may be the turn farthest from the center of the working coil (WC) among the ten turns (T).

[0159] When a working coil (WC) is formed by 10 turns (T), the turns may be the first to tenth turns (T1, T2, T3, T4, T5, T7, T8, T9, T10) in order from the turn closest to the center of the working coil (WC) to the turn furthest from the center.

[0160] Each turn (T) of the working coil (WC) may be formed to have a predetermined interval (dn) with respect to other adjacent turns. The interval (dn) between each turn of the working coil (WC) may include a first interval to a ninth interval (dn1, dn2, dn3, dn4, dn5, dn6, dn7, dn8, dn9). However, this is merely an example, and the number of intervals (dn) between each turn may vary depending on the number of turns (T).

[0161] The first interval (dn1) may be the interval between the first turn (T1) and the second turn (T2). Additionally, the ninth interval (dn9) may be the interval between the ninth turn (T9) and the tenth turn (T10).

[0162] When the working coil (WC) is formed of 10 turns (T), the interval (dn) between each turn may be the first to ninth intervals (dn1, dn2, dn3, dn4, dn5, dn6, dn7, dn8, dn9) in order from the closest interval to the farthest interval from the center of the working coil (WC).

[0163] As illustrated in Fig. 8, the intervals (dn) between each turn of the working coil (WC) can be formed equally. The first to ninth intervals (dn1, dn2, dn3, dn4, dn5, dn6, dn7, dn8, dn9) can all be formed equally.

[0164] A working coil (WC) having an equal spacing (dn) between each turn of the working coil (WC) may be a uniform working coil (WC1).

[0165] However, in the case of a uniform working coil (WC1), there is a problem in that it is difficult to maximize heating efficiency because the magnetic field is not concentrated on the heated object (HO).

[0166] The strength of the magnetic field generated in the working coil (WC) may vary depending on the average magnetic flux length of the working coil (WC).

[0167] The average magnetic flux length of the working coil (WC) may be the average of the magnetic path lengths of each turn (T).

[0168] Regarding the magnetic path of each turn (T) of the working coil (WC), a description is given with reference to FIGS. 9 to 13.

[0169] Figures 9 and 10 are drawings for explaining the magnetic path length according to the magnetic path of each turn.

[0170] Fig. 9 is a diagram showing the magnetic path length of one of the multiple turns (T) forming a working coil (WC). In addition, Fig. 10 shows the magnetic path length of a turn further from the center of the working coil (WC) than the turn of Fig. 9.

[0171] The magnetic flux generated in each turn (T) of the working coil (WC) can flow along the magnetic path (MP).

[0172] The magnetic conductivity of air can be lower than that of metal. Therefore, when a magnetic path (MP) includes air, the magnetic path length can be longer than when it does not include air. When a magnetic path (MP) includes only metal, it can have a minimum magnetic path length.

[0173] The right magnetic path (lright) of Fig. 9 includes only the heated object (pot) made of metal. On the other hand, the right magnetic path (lright) of Fig. 10 includes not only the heated object (pot) made of metal, but also air.

[0174] Accordingly, the length of the right magnetic path (lright) of Fig. 10 is longer than the length of the right magnetic path (lright) of Fig. 9. Therefore, the total magnetic path length of Fig. 10 is longer than the total magnetic path length of Fig. 9.

[0175] That is, the farther the turn (T) is from the center of the working coil (WC), the longer the magnetic path length of the turn (T).

[0176] Meanwhile, the closer the turn (T) is to the center of the working coil (WC), the smaller the diameter of the turn (T), so that the magnetic fluxes generated in the turn (T) can cancel each other out. Accordingly, the path of the magnetic path of the turn (T) that passes through the heated object (HO) made of metal can be reduced.

[0177] Therefore, the closer the turn (T) is to the center of the working coil (WC), the longer the magnetic path length of the turn (T).

[0178] Next, with reference to FIG. 11, the magnetic path length of each turn (T) of the working coil (WC) will be described.

[0179] Figure 11 is a graph showing the magnetic path length of each turn of the working coil.

[0180] Specifically, FIG. 11 is a graph showing the magnetic path length (MPL) for each of a plurality of turns of the uniform working coil (WC1) as illustrated in FIG. 8.

[0181] Referring to Fig. 11, the magnetic path lengths of the magnetic fields generated in the fifth turn (T5) and the sixth turn (T6) are the shortest. From this, it can be seen that the magnetic path length of the turn whose distance from the center of the working coil (WC) is the median among the multiple turns (T) is the shortest.

[0182] Meanwhile, the longer the distance between the center of the working coil (WC) and the turns based on the fifth turn (T5) and the sixth turn (T6), the longer the magnetic path length. Also, the shorter the distance between the center of the working coil (WC) and the turns based on the fifth turn (T5) and the sixth turn (T6), the longer the magnetic path length.

[0183] In this way, the closer or farther the distance between the center of the working coil (WC) and the turn (T) is, the longer the magnetic path length of the turn (T). Accordingly, the average magnetic flux length of the working coil (WC) is also longer.

[0184] Meanwhile, the strength of the magnetic field generated by the working coil (WC) or each turn (T) of the working coil (WC) can be calculated by the mathematical expression 1 below.

[0185]

[0186] According to mathematical expression 1, the magnetic field (H) is proportional to the number of turns (N) and the input peak current (Ipeak), and inversely proportional to the average magnetic flux length (l) or magnetic path length (l).

[0187] That is, the strength of the magnetic field (H) generated by the working coil (WC) is weaker as the average magnetic flux length (l) is longer. Alternatively, the strength of the magnetic field (H) generated by the working coil (WC) is stronger as the average magnetic flux length (l) is shorter.

[0188] Additionally, the strength of the magnetic field (H) generated by each turn (T) of the working coil (WC) is weaker as the magnetic path length (l) is longer. Alternatively, the strength of the magnetic field (H) generated by each turn (T) of the working coil (WC) is stronger as the magnetic path length (l) is shorter.

[0189] Therefore, the strength of the magnetic field (H) generated by the first turn (T1) and the tenth turn (T10) may be the weakest. Additionally, the strength of the magnetic field (H) generated by the fifth turn (T5) and the sixth turn (T6) may be the strongest.

[0190] Meanwhile, the current density (J) of the heated object (HO) can be proportional to the strength of the magnetic field (H).

[0191] In relation to this, it is explained with reference to Fig. 12.

[0192] Figure 12 is a graph showing the current density of a heated object.

[0193] Specifically, Fig. 12 shows the current density (J) of a heated object (HO) heated by a uniform working coil.

[0194] Figure 12 is a graph showing the current density (J) of a heated object (HO) according to the distance from the center of the heated object (HO) with a radius of, for example, 110 mm.

[0195] Referring to Fig. 12, the current density (J) has a maximum value at a point where the distance from the center of the object to be heated (HO) is, for example, about 55 mm. Meanwhile, the current density (J) decreases as the distance from the center of the object to be heated (HO) is increased.

[0196] Meanwhile, the higher the current density (J) of the heated object (HO), the higher the heat loss.

[0197] Next, with reference to Fig. 13, the heat loss by area of ​​the heated object (HO) is described.

[0198] Fig. 13 is a drawing showing an example of the area-specific heat loss (EM-Loss) of a heated object (HO) heated by a uniform working coil.

[0199] When the object to be heated (HO) is heated by a uniform working coil (WC1), the area of ​​the bottom surface of the object to be heated (HO) can be divided into a first area (A1), a second area (A2), a third area (A3), a fourth area (A4), and a fifth area (A5).

[0200] The area of ​​the object to be heated (HO) with the greatest amount of heat loss may be the concentrated heating area.

[0201] Referring to the example of Fig. 13, the third region (A3) among the regions of the heated object (HO) has the largest amount of heat loss. In other words, the concentrated heating region may be the third region (A3).

[0202] Additionally, the heat loss in the third area (A3) may be approximately 5^10[W / m^3]. That is, the maximum heat loss of the heated object (HO) may be approximately 5^10[W / m^3].

[0203] Meanwhile, the third region (A3) may be a region including a point whose distance from the center of the heated object (HO) is approximately 55 mm. Alternatively, the third region (A3) may be a region where at least a portion of the fifth turn (T5) or the sixth turn (T6) is positioned below. Alternatively, the third region (A3) may be a point where at least a portion of the fifth gap (dn5) is positioned below.

[0204] As described in FIGS. 8 to 13, the maximum heat loss of the heated object (HO) may vary depending on the arrangement of the plurality of turns (T) forming the working coil (WC).

[0205] Additionally, depending on the arrangement of the plurality of turns (T) forming the working coil (WC), the location or size of the area where the heated object (HO) has the maximum heat loss may be different.

[0206] Accordingly, the present disclosure seeks to provide a working coil (WC) that maximizes heating efficiency by increasing the maximum heat loss of a heated object (HO).

[0207] In addition, the present disclosure seeks to provide a working coil (WC) that maximizes heating efficiency by controlling the size or location of an area where a heated object (HO) has maximum heat loss.

[0208] The present disclosure seeks to provide a cooking appliance (1) that improves the maximum heat loss of a heated object (HO).

[0209] In addition, the present disclosure seeks to provide a cooking appliance (1) that controls the size or location of an area having the maximum heat loss among areas of a heated object (HO).

[0210] For this purpose, the spacing (dn) between each turn (T) forming the working coil (WC) of the cooking appliance (1) according to the embodiment of the present disclosure may not be uniform.

[0211] First, the working coil of the cooking device (1) according to the first embodiment of the present disclosure will be described with reference to FIGS. 14 to 17.

[0212] FIG. 14 is a drawing illustrating the shape of a working coil according to the first embodiment of the present disclosure.

[0213] The working coil (WC2) of Fig. 14 may be a working coil having the same outer and inner diameters as the uniform working coil (WC1) of Fig. 8. In addition, the working coil (WC2) of Fig. 14 may be a working coil formed of the first to tenth turns (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10) like the uniform working coil (WC1) of Fig. 8.

[0214] However, the interval (dn) between each turn of the working coil (WC2) of Fig. 14 may not be uniform, unlike the uniform working coil (WC1) of Fig. 8.

[0215] Specifically, the interval (dn) between each turn of the working coil (WC2) may decrease as it moves away from the center of the working coil (WC). A working coil in which the interval (dn) between each turn decreases as it moves away from the center of the working coil may be a reverse-type working coil (WC2).

[0216] The interval (dn) between each turn of the working coil (WC2) can be reduced by a predetermined interval as it moves away from the center of the working coil (WC).

[0217] For example, the predetermined spacing may be 0.5 mm. Accordingly, when the first spacing (dn1) is 4.5 mm, the second spacing (dn2) may be 4.0 mm, the third spacing (dn3) may be 3.5 mm, the fourth spacing (dn4) may be 3.0 mm, the fifth spacing (dn5) may be 2.5 mm, the sixth spacing (dn6) may be 2.0 mm, the seventh spacing (dn7) may be 1.5 mm, the eighth spacing (dn8) may be 1.0 mm, and the ninth spacing (dn9) may be 0.5 mm.

[0218] Accordingly, the equivalent inductance (Leq) can be 6.92 μH, which is 38.12% larger than the case including the uniform working coil (WC1). In addition, the equivalent resistance (Req) of the cooking appliance (1) can be 348.2 mΩ, which is 38.09% larger than the case including the uniform working coil (WC1).

[0219] As the equivalent inductance (Leq) and equivalent resistance (Req) increase, the resonant current decreases, which can reduce switching losses. As switching losses decrease, heating efficiency can increase.

[0220] Meanwhile, according to an embodiment, the interval (dn) between each turn of the working coil (WC2) may decrease by a predetermined ratio as it moves away from the center of the working coil (WC).

[0221] For example, the predetermined ratio may be 10%. Accordingly, when the first gap (dn1) is 10.0 mm, the second gap (dn2) may be 9.0 mm. Additionally, the third gap (dn3) may be 8.1 mm.

[0222] Next, the magnetic path length and average magnetic flux length of each turn (T) of the reverse-type working coil (WC2) are described.

[0223] Figure 15 is a graph showing the magnetic path length of each turn of the working coil.

[0224] Specifically, Fig. 15 shows the magnetic path length (MPL_asy_re) according to each turn (T) of the reverse-type working coil (WC2). In addition, Fig. 15 shows the magnetic path length (MPL) according to each turn (T) of the uniform-type working coil (WC1).

[0225] The average magnetic flux length of the working coil (WC) may be the average of the magnetic path lengths of each turn (T).

[0226] From Fig. 15, it can be deduced that the average magnetic flux length of the reverse-type working coil (WC2) is shorter than the average magnetic flux length of the equal-type working coil (WC1).

[0227] As mentioned above, the shorter the average flux length of the working coil (WC), the stronger the magnetic field generated from the working coil (WC). Therefore, the magnetic field generated from the reverse-type working coil (WC2) may be stronger than the magnetic field generated from the uniform-type working coil (WC1).

[0228] Accordingly, the heating efficiency of the reverse-type working coil (WC1) may be higher than that of the equal-type working coil (WC1).

[0229] Next, the current density of the heated object (HO) heated by the reverse-type working coil (WC2) is described.

[0230] Figure 16 is a graph showing the current density of a heated object.

[0231] Specifically, Fig. 16 shows the current density (Asy_reverse_Mag_J) of the object to be heated (HO) heated by the reverse-type working coil (WC2). In addition, Fig. 16 shows the current density (Space_Mag_J) of the object to be heated (HO) heated by the uniform-type working coil (WC1).

[0232] Referring to Fig. 16, when the object to be heated (HO) is heated by the reverse-type working coil (WC2), the current density has a maximum value at a point about 75 mm away from the center of the object to be heated (HO). Meanwhile, the current density decreases as the distance from the point about 75 mm away from the center of the object to be heated (HO) increases.

[0233] Meanwhile, when the object to be heated (HO) is heated by the uniform working coil (WC1), the current density has a maximum value at a point where the distance from the center of the object to be heated (HO) is approximately 55 mm.

[0234] That is, the current density of the heated object (HO) heated by the reverse-type working coil (WC2) has a maximum value at a point farther from the center of the working coil (WC) than the current density of the heated object (HO) heated by the uniform-type working coil (WC1).

[0235] Additionally, the maximum current density of the object to be heated (HO) heated by the reverse-type working coil (WC2) may be a value that is 7.9% higher than the maximum current density of the object to be heated (HO) heated by the uniform-type working coil (WC1).

[0236] Next, referring to Fig. 17, the heat loss by area of ​​the heated object (HO) heated by the reverse-type working coil (WC2) is described.

[0237] Fig. 17 is a drawing showing an example of the area-specific heat loss (EM-Loss) of a heated object heated by a reverse-type working coil.

[0238] When a heated object (HO) is heated by a uniform working coil (WC1), the area of ​​the bottom surface of the heated object (HO) can be divided into a first area (B1), a second area (B2), a third area (B3), a fourth area (B4), and a fifth area (B5).

[0239] The area of ​​the object to be heated (HO) with the greatest amount of heat loss may be the concentrated heating area.

[0240] Referring to the example of Fig. 17, the third region (B3) among the regions of the heated object (HO) has the largest amount of heat loss. In other words, the concentrated heating region may be the third region (B3).

[0241] Additionally, the heat loss in the third region (B3) may be approximately 6^10[W / m^3]. That is, the maximum heat loss of the heated object (HO) may be approximately 6^10[W / m^3].

[0242] As described above in Fig. 13, when heating an object to be heated (HO) using a uniform working coil (WC1), the maximum heat loss of the object to be heated (HO) can be about 5^10[W / m^3].

[0243] That is, the maximum heat loss of the object to be heated (HO) heated by the reverse-type working coil (WC2) is greater than the maximum heat loss of the object to be heated (HO) heated by the uniform-type working coil (WC1).

[0244] Meanwhile, the third region (B3) may be a region including a point whose distance from the center of the heated object (HO) is approximately 75 mm. Alternatively, the third region (B3) may be a region where at least a portion of the sixth turn (T6) and the seventh turn (T7) are positioned below. Alternatively, the third region (B3) may be a region where at least a portion of the sixth gap (dn6) is positioned below.

[0245] As described above in Fig. 13, when heating an object to be heated (HO) using a uniform working coil (WC1), the concentrated heating area may be an area including a point whose distance from the center of the object to be heated (HO) is approximately 55 mm.

[0246] That is, the concentrated heating area of ​​the object to be heated (HO) heated by the reverse-type working coil (WC2) can be formed further from the center of the working coil (WC) than the concentrated heating area of ​​the object to be heated (HO) heated by the uniform-type working coil (WC1).

[0247] Accordingly, the load of the heated object (HO) can be heated evenly by concentrating the heating over a larger radius than when using a uniform working coil (WC1). In particular, the lower portion of the load can be heated evenly in the horizontal direction.

[0248] To summarize FIGS. 15 to 17, the cooking appliance (1) according to the first embodiment of the present disclosure can increase the amount of heat loss of the heated object (HO).

[0249] Accordingly, the cooking appliance (1) according to the first embodiment of the present disclosure can maximize heating efficiency.

[0250] Next, the working coil of the cooking device (1) according to the second embodiment of the present disclosure will be described with reference to FIGS. 18 to 21.

[0251] FIG. 18 is a drawing illustrating the shape of a working coil according to a second embodiment of the present disclosure.

[0252] The working coil (WC3) of Fig. 18 may be a working coil having the same outer and inner diameters as the uniform working coil (WC1) of Fig. 8. In addition, the working coil (WC3) of Fig. 18 may be a working coil formed of the first to tenth turns (T1, T2, T3, T4, T5, T6, T7, T8, T9, T10) like the uniform working coil (WC1) of Fig. 8.

[0253] However, the interval (dn) between each turn of the working coil (WC3) of FIG. 18 may not be uniform, unlike the uniform working coil (WC1) of FIG. 8.

[0254] Specifically, the interval (dn) between each turn of the working coil (WC3) may increase as it moves away from the center of the working coil (WC). A working coil in which the interval (dn) between each turn increases as it moves away from the center of the working coil may be a forward-type working coil (WC3).

[0255] That is, the interval between each turn (t) of the working coil (WC3) can increase as it moves away from the center of the working coil (WC3).

[0256] For example, the predetermined spacing may be 0.5 mm. Accordingly, when the first spacing (dn1) is 0.5 mm, the second spacing (dn2) may be 1.0 mm, the third spacing (dn3) may be 1.5 mm, the fourth spacing (dn4) may be 2.0 mm, the fifth spacing (dn5) may be 2.5 mm, the sixth spacing (dn6) may be 3.0 mm, the seventh spacing (dn7) may be 3.5 mm, the eighth spacing (dn8) may be 4.0 mm, and the ninth spacing (dn9) may be 4.5 mm.

[0257] Accordingly, the equivalent inductance (Leq) can be 5.28 μH, which is 5.4% larger than the case including the uniform working coil (WC1). In addition, the equivalent resistance (Req) of the cooking appliance (1) can be 270.69 mΩ, which is 7.35% larger than the case including the uniform working coil (WC1).

[0258] As the equivalent inductance (Leq) and equivalent resistance (Req) increase, the resonant current decreases, which can reduce switching losses. As switching losses decrease, heating efficiency can increase.

[0259] Meanwhile, according to an embodiment, the interval between each turn (T) of the working coil (WC3) may increase by a predetermined ratio as it moves away from the center of the working coil (WC3).

[0260] For example, the predetermined ratio may be 10%. Accordingly, when the first gap (dn1) is 10.0 mm, the second gap (dn2) may be 11.0 mm. Additionally, the third gap (dn3) may be 12.1 mm.

[0261] Next, the magnetic path length and average magnetic flux length of each turn (T) of the forward-type working coil (WC3) are described.

[0262] Figure 19 is a graph showing the magnetic path length of each turn of the working coil.

[0263] Specifically, Fig. 19 shows the magnetic path length (MPL_asy_fo) according to each turn (T) of the forward-type working coil (WC3). In addition, Fig. 19 shows the magnetic path length (MPL) according to each turn (T) of the uniform-type working coil (WC1).

[0264] The average magnetic flux length of the working coil (WC) may be the average of the magnetic path lengths of each turn (T).

[0265] From Fig. 19, it can be deduced that the average magnetic flux length of the forward-type working coil (WC3) is shorter than the average magnetic flux length of the uniform-type working coil (WC1).

[0266] As mentioned above, the shorter the average flux length of the working coil (WC), the stronger the magnetic field generated from the working coil (WC). Therefore, the magnetic field generated from the forward-type working coil (WC3) may be stronger than the magnetic field generated from the uniform-type working coil (WC1).

[0267] Accordingly, the heating efficiency of the forward-type working coil (WC3) may be higher than that of the equal-type working coil (WC1).

[0268] Next, the current density of the heated object (HO) heated by the forward-type working coil (WC3) is described.

[0269] Figure 20 is a graph showing the current density of a heated object.

[0270] Specifically, Fig. 20 shows the current density (Asy_forward_Mag_J) of the object to be heated (HO) heated by the forward-type working coil (WC3). In addition, Fig. 20 shows the current density (Space_Mag_J) of the object to be heated (HO) heated by the uniform-type working coil (WC1).

[0271] Referring to Fig. 20, when the object to be heated (HO) is heated by the forward-type working coil (WC3), the current density has a maximum value at a point about 30 mm away from the center of the object to be heated (HO). Meanwhile, the current density decreases as the distance from the point about 30 mm away from the center of the object to be heated (HO) increases.

[0272] Meanwhile, when the object to be heated (HO) is heated by the uniform working coil (WC1), the current density has a maximum value at a point where the distance from the center of the object to be heated (HO) is approximately 55 mm.

[0273] That is, the current density of the heated object (HO) heated by the forward-type working coil (WC3) has a maximum value at a point closer to the center of the working coil (WC) than the current density of the heated object (HO) heated by the uniform-type working coil (WC1).

[0274] Additionally, the maximum current density of the object to be heated (HO) heated by the forward-type working coil (WC3) may be a value that is 8.5% higher than the maximum current density of the object to be heated (HO) heated by the uniform-type working coil (WC1).

[0275] Next, referring to Fig. 21, the heat loss by area of ​​the heated object (HO) heated by the forward-type working coil (WC3) is described.

[0276] Fig. 21 is a drawing showing an example of the area-specific heat loss (EM-Loss) of a heated object heated by a forward-type working coil.

[0277] When the object to be heated (HO) is heated by a forward-type working coil (WC3), the area of ​​the bottom surface of the object to be heated (HO) can be divided into a first area (C1), a second area (C2), a third area (C3), a fourth area (C4), and a fifth area (C5).

[0278] The area of ​​the object to be heated (HO) with the greatest amount of heat loss may be the concentrated heating area.

[0279] Referring to the example of Fig. 21, the third region (C3) among the regions of the heated object (HO) has the largest amount of heat loss. In other words, the concentrated heating region may be the third region (C3).

[0280] Additionally, the heat loss in the third region (C3) may be approximately 6^10[W / m^3]. That is, the maximum heat loss of the heated object (HO) may be approximately 7^10[W / m^3].

[0281] As described above in Fig. 13, when heating an object to be heated (HO) using a uniform working coil (WC1), the maximum heat loss of the object to be heated (HO) can be about 5^10[W / m^3].

[0282] That is, the maximum heat loss of the object to be heated (HO) heated by the forward-type working coil (WC3) is greater than the maximum heat loss of the object to be heated (HO) heated by the uniform-type working coil (WC1).

[0283] Meanwhile, the third region (C3) may be a region including a point whose distance from the center of the heated object (HO) is approximately 30 mm. Alternatively, the third region (C3) may be a region where at least a portion of the fourth turn (T4) and the fifth turn (T5) are positioned below. Alternatively, the third region (C3) may be a region where at least a portion of the fourth gap (dn4) is positioned below.

[0284] As described above in Fig. 13, when heating an object to be heated (HO) using a uniform working coil (WC1), the concentrated heating area may be an area including a point whose distance from the center of the object to be heated (HO) is approximately 55 mm.

[0285] That is, the concentrated heating area of ​​the object to be heated (HO) heated by the forward-type working coil (WC3) can be formed closer to the center of the working coil (WC) than the concentrated heating area of ​​the object to be heated (HO) heated by the uniform-type working coil (WC1).

[0286] Accordingly, the load can be heated more evenly than when using a uniform working coil (WC1). In particular, the load can be heated evenly in the vertical direction.

[0287] To summarize FIGS. 18 to 21, the cooking appliance (1) according to the second embodiment of the present disclosure can increase the heat loss of the heated object (HO) by including a forward-type working coil (WC3).

[0288] Accordingly, the cooking appliance (1) according to the second embodiment of the present disclosure can maximize heating efficiency.

[0289] Meanwhile, the shape of the working coil (WC) included in the cooking device (1) of the present disclosure is not limited to the first and second embodiments, and may include any shape in which the spacing between each turn (T) is not equal.

[0290] That is, at least one of the intervals between each turn of the working coil (WC) may be different from the remaining intervals. Alternatively, the intervals between each turn of the working coil (WC) may be different from each other.

[0291] Additionally, the turn spacing between the center of the working coil (WC) and the first reference turn and the turn spacing between the first reference turn and the second reference turn forming the outermost part of the working coil may be different from each other.

[0292] Specifically, the gap between the first turn and the second reference turn may be narrower than the gap between the turns between the center of the working coil (WC) and the first reference turn.

[0293] Alternatively, the spacing between the first turn and the second reference turn may be wider than the spacing between the turns between the center of the working coil (WC) and the first reference turn.

[0294] In the following, the present disclosure is described in particular using the aforementioned working coil (WC) as an example of a printed circuit board (PCB) working coil.

[0295] The PCB working coil may also be referred to as a PCB pattern coil, but the scope of the present disclosure should not be construed as being limited by such terms.

[0296] The cooking appliances that use PCB working coils are described as follows.

[0297] In the case of a PCB working coil having a pattern with a fixed (or equal) spacing (or interval), the magnetic field is concentrated inside, causing severe heat generation, which affects the operation of the PCB working coil or cooking device (1).

[0298] In particular, the aforementioned heat generation problem can be exacerbated when the PCB working coil operates at high frequencies. Furthermore, for PCB working coils, the closer they are to the center, the more severe the heat generation problem tends to be.

[0299] The present disclosure provides a cooking appliance including a PCB working coil, and discloses a PCB working coil having a reduced heat generation problem compared to a conventional one even when operating at high frequency, and a cooking appliance (1) including (or employing) such a PCB working coil.

[0300] In order to reduce heat generation problems even when operating at high frequencies, the PCB working coil according to the present disclosure can utilize various methods such as PCB pattern structure, arrangement, and shape.

[0301] In the present disclosure, a PCB working coil is disclosed that is designed to reduce heat generation in a PCB working coil during high-frequency operation by lowering the magnetic flux affecting the winding, disposing the current density asymmetrically (e.g., asymmetric arrangement of DC resistance), and ensuring that the separation distance between turns is not equal.

[0302] A cooking appliance (1) according to at least one of the various embodiments of the present disclosure may include a top plate (15) on which a heated object (HO) is placed, a plurality of working coils (WCs) for heating the heated object (HO), an inverter (140) for applying current to each of the working coils (WC), and a controller for controlling the operation of the inverter (140) so that the heated object (HO) is heated through each of the working coils (WC).

[0303] When a plurality of working coils (WCs) rather than one are employed in the cooking appliance (1), at least one of the plurality of working coils (WCs) may be a PCB working coil.

[0304] A PCB working coil may contain one or more turns.

[0305] Each turn can be a bundle of one or more Unit Coils.

[0306] When a PCB working coil is composed of multiple turns, the spacing (or distance) between each turn may be uniform. In this case, even if the spacing between turns is uniform, the configuration of each turn may be different from that of other turns.

[0307] In some embodiments, when the PCB working coil is composed of multiple turns, the spacing between at least one turn may be different from the spacing between other turns, i.e., the spacing between turns may not be uniform. Even in this case, the configuration of each turn may be the same as or different from the other turns.

[0308] Hereinafter, a PCB working coil according to various embodiments of the present disclosure is disclosed. In this case, the PCB working coil (WC) is composed of a plurality of turns, and for convenience of explanation, the number of turns is described as 6 (T1 to T6) as an example.

[0309] Figure 22 is a drawing illustrating a PCB working coil.

[0310] Figure 22 (a) shows a top-view of a PCB working coil composed of multiple turns (T1-T6).

[0311] The PCB working coil can be divided into a heated region and a non-heated region. However, this division is for convenience of explanation only, and the present disclosure is not limited to such division.

[0312] The heated region may refer to a region where turns (T1-T6) are arranged. On the other hand, the non-heated region may refer to a region that is not a heated region, i.e., a region where turns (T1-T6) are not arranged. In other words, the region between turns may be considered a non-heated region. This non-heated region may also include a central region where turns are not arranged. The central region may include a center point (c). Here, the center point (c) may be a concept arbitrarily defined to describe components of variously configured PCB working coils according to the present disclosure.

[0313] In the following disclosure, a PCB working coil having a circular shape is used as an example, but it should be noted in advance that the present invention is not limited thereto. For example, the PCB working coil may have a polygonal shape such as an oval, rectangle, or square.

[0314] Meanwhile, (b) of Fig. 22 may be a cross-sectional view of a dotted box portion representing a part of the PCB working coil illustrated in (a) of Fig. 22.

[0315] Referring to (b) of Fig. 22, it can be seen that the PCB working coil has turns (T1-T6) with a predefined turn width (tw: width of a turn) arranged at a predefined interval (dn12-dn56).

[0316] For example, the first turn (T1) is a turn arranged at the position closest to the center point (c), i.e., the innermost angle of the PCB working coil, and may have a first turn width (tw1). The second turn (T2) is a turn arranged at the position following the first turn (T1) and may have a second turn width (tw2). At this time, the interval between the first turn (T1) and the second turn (T2) may be named dn12, and its value may be determined in advance. The third turn (T3) is a turn arranged at the position following the second turn (T2) and may have a third turn width (tw3). At this time, the interval between the second turn (T2) and the third turn (T3) may be named dn23, and its value may be determined in advance. The fourth turn (T4) is a turn arranged at the next position of the third turn (T3) and may have a fourth turn width (tw4). At this time, the interval between the third turn (T3) and the fourth turn (T4) may be named dn34, and its value may be determined in advance. The fifth turn (T5) is a turn arranged at the next position of the fourth turn (T4) and may have a fifth turn width (tw5). At this time, the interval between the fourth turn (T5) and the fifth turn (T5) may be named dn45, and its value may be determined in advance. The sixth turn (T6) is a turn arranged at the farthest position from the center point (c), i.e., the outermost of the PCB working coil, and may have a sixth turn width (tw6). At this time, the interval between the fifth turn (T5) and the sixth turn (T6) can be named dn56, and its value can be determined in advance.

[0317] As described above, the configuration of the PCB working coil according to the present disclosure can adjust factors, such as the turn spacing (dn), turn width (tw), spacing between unit coils within a turn (ds), and the number of strands of unit coils within a turn, in order to solve the heat generation problem.

[0318] FIG. 23 is a drawing illustrating an interval between turns according to one embodiment of the present disclosure.

[0319] In the graphs of (a) and (b) of Fig. 23, the vertical axis may represent the interval (dn) between turns, and the horizontal axis may represent the number of turns (e.g., T1-T6). Meanwhile, the graphs of (a) and (b) of Fig. 23 describe the interval between turns versus the number of turns according to oz. Here, oz may represent, for example, the thickness of the PCB working coil. In Fig. 23 (a) and (b), the graphs are shown using 3oz to 6oz as examples, but 2oz may also be included. However, when a large current is used, 3oz or more may be preferable.

[0320] Referring to (a) of Fig. 23, it can be seen that as the number of turns increases, the interval between turns decreases. In this case, the decrease in the interval between turns may be linear.

[0321] Additionally, in (a) of Fig. 23, it can be seen that the interval between turns decreases with respect to the number of turns for each oz.

[0322] Referring to (a) of Fig. 23, the number of turns on the horizontal axis 1 may represent T1, 2 may represent T2, 3 may represent T3, 4 may represent T4, 5 may represent T5, and 6 may represent T6.

[0323] Accordingly, when interpreting the graph of (a) of Fig. 23, the distance between turns may become narrower (in the direction from T1 to T6) as one moves away from the center point (c) of the PCB coil (500). Conversely, the distance between turns may become wider or larger as one moves closer to the center point (c) of the PCB coil (500) (in the direction from T6 to T1).

[0324] Fig. 23 (b) is the opposite of Fig. 6 (a). In other words, when interpreting the graph of Fig. 23 (b), the turn spacing may increase as one moves away from the center point (c) of the PCB coil (500) (in the direction from T1 to T6).

[0325] FIG. 24 is a drawing illustrating an interval between turns according to another embodiment of the present disclosure.

[0326] The basic description of the graphs of (a) and (b) of Fig. 24 is the same as the basic description of the graphs of (a) and (b) of Fig. 23 described above, so overlapping content is omitted and the differences from (a) and (b) of Fig. 23 described above are mainly described below.

[0327] In the graphs (a) and (b) of FIG. 23 described above, the interval between turns increases and decreases linearly with respect to the number of turns. However, referring to FIG. 24 (a) and (b), the interval between turns may not increase and decrease linearly with respect to the number of turns.

[0328] The interval between turns in the graphs (a) and (b) of Figure 24 may include nonlinear sections.

[0329] Alternatively, referring to (a) and (b) of FIG. 24, a section in which the slope representing the increase or decrease in the interval between turns relative to the number of turns changes and a section in which the slope does not change may be included.

[0330] Meanwhile, referring to the graphs illustrated in (a) and (b) of Fig. 24, there may be multiple sections in which the slope, which represents the increase or decrease in the interval between turns relative to the number of turns, changes. In this case, the slopes in each section may be different from each other.

[0331] Referring to the graph shown in (a) of Figure 24, it can be seen that the interval between turns relative to the number of turns does not change until a certain turn, but gradually decreases (negative slope) after that turn.

[0332] Referring to the graph in (a) of Fig. 24, there is no change in the turn-to-turn interval between T1 and T3. That is, the turn-to-turn intervals between T1 and T2 and between T2 and T3 may be the same (or equal). On the other hand, it can be seen that the turn-to-turn interval between T3 and T4 changes primarily. The turn-to-turn interval between T3 and T4 may be different from the turn-to-turn intervals between previous turns (the turn-to-turn intervals between T1 and T2 and between T2 and T3). In addition, it can be seen that the turn-to-turn intervals between T4 and T5 and between T5 and T6 also change secondarily. For example, the turn-to-turn interval between T4 and T5 may be different not only from the turn-to-turn interval between T3 and T4, but also from the turn-to-turn intervals between T1 and T2 and T2 and T3. Additionally, the turn interval between T5 and T6 may also be different from the turn interval between T4 and T5 described above.

[0333] On the other hand, referring to the graph shown in (b) of Figure 24, it can be seen that the interval between turns relative to the number of turns does not change until a certain turn, but gradually increases (positive slope) after that turn.

[0334] In the graph of Fig. 24(b), the turn intervals between T1 and T2 and between T2 and T3 may remain constant without change. In other words, the turn intervals between T1 and T2 and between T2 and T3 may be the same. Meanwhile, it can be seen that the turn interval between T3 and T4 changes primarily. The turn interval between T3 and T4 may be different from the turn intervals between previous turns. That is, the turn interval between T3 and T4 may increase compared to the turn intervals between T1-T2 and T2-T3. It can also be seen that the turn intervals between T4 and T5 and between T5 and T6 change secondarily. At this time, the turn intervals between T4 and T5 and the turn intervals between T5 and T6 may be different from the turn intervals between previous turns. That is, the turn-to-turn interval between T4 and T5 and the turn-to-turn interval between T5 and T6 may increase compared to the turn-to-turn intervals between T1 and T2 and T2 and T3, as well as the turn-to-turn interval between T3 and T4. Furthermore, the turn-to-turn interval between T5 and T6 may also differ from the turn-to-turn interval between T4 and T5 described above.

[0335] The following Figures 25 to 27 illustrate embodiments with reference to the graph of Figure 23 (a), but are not necessarily limited thereto.

[0336] In each drawing, as described above, T1 is described as the turn placed closest to the center point (c) (i.e., the innermost turn) and T6 is described as the turn placed farthest from the center point (c) (i.e., the outermost turn).

[0337] In the following drawings, all factors not specifically mentioned can be assumed to be the same. For example, in Fig. 25, the turn-to-turn spacing is mentioned, and the remaining turn width, the width of the unit coils within the turn, the spacing between the unit coils, and the number of unit coils can be assumed to be the same.

[0338] FIGS. 25 to 27 are drawings illustrating a PCB working coil in which turns are arranged according to embodiments of the present disclosure.

[0339] First, in (a) of Fig. 25, a top view of a PCB coil consisting of six turns (T1-T6) is shown, and in (b) of Fig. 25, a cross-sectional view of the turns within the dotted box shown in (a) of Fig. 25 is shown.

[0340] Referring to (a) and (b) of Fig. 25, a PCB working coil configured with reference to the graph illustrated in (a) of Fig. 23 can be represented.

[0341] At this time, the turn width (tw) of each turn (T1-T6) constituting the PCB working coil can be the same.

[0342] As shown in the graph in (a) of Fig. 23, it can be seen that as the number of turns increases, the interval between turns decreases, as shown in (b) of Fig. 25.

[0343] In other words, referring to (b) of FIG. 25, it can be seen that the turn-to-turn interval (dn12) between T1 and T2 is relatively larger than the turn-to-turn interval (dn23) between T2 and T3. Similarly, it can be seen that dn23 is relatively larger than the turn-to-turn interval (dn34) between T3 and T4, the turn-to-turn interval (dn45) between T4 and T5, and the turn-to-turn interval (dn56) between T5 and T6. That is, the turn-to-turn interval gradually decreases relative to the number of turns, and dn12 > dn23 > dn34 > dn45 > dn56.

[0344] Next, in Fig. 26, there is an embodiment in which the spacing (dn) between each turn in the PCB working coil is equal, but the turn width (tw) is adjusted.

[0345] In Fig. 26 (a), a PCB working coil having six turns (T1-T6) is illustrated, and in Fig. 26 (b), a cross-sectional view of the turns within the dotted box illustrated in Fig. 26 (a) is illustrated.

[0346] Referring to (a) and (b) of Fig. 26, it can be seen that the turn intervals (dn) of T1-T6 are all the same.

[0347] At this time, it can be seen that the turn width (tw) of each turn (T1-T6) is different.

[0348] Referring to (b) of Fig. 26, the turn width (tw1) of T1 may be different from the turn width (tw2) of T2 to the turn width (tw6) of T6.

[0349] Specifically, the turn width (tw1) of T1 may be a relatively larger value than the turn width (tw2) of T2 to the turn width (tw6) of T6. And the turn width (tw2) of T2 may be a relatively larger value than the turn width (tw3) of T3 to the turn width (tw6) of T6. From these characteristics, it can be seen that tw1 > tw2 > tw3 > tw4 > tw5 > tw6. In a similar concept, the turn width (tw6) of T6, which is the outermost turn, may have the smallest turn width among all turns of the PCB working coil, and conversely, the turn width (tw1) of T1, which is the innermost turn, may have the largest turn width among all turns of the PCB working coil. At this time, the turn widths of the remaining turns between T1 and T6 may be arbitrary (for example, a tw value between tw1 and tw6).

[0350] Even if the turn widths of each turn constituting the PCB working coil in (b) of Fig. 26 are different, the number of unit coils constituting one turn may or may not be the same for each turn.

[0351] Next, Fig. 27 is an example of adjusting both the turn width and the turn spacing of each turn in the PCB working coil.

[0352] In Fig. 27 (a), a PCB working coil having six turns (T1-T6) is illustrated, and in Fig. 27 (b), a cross-sectional view of the turns within the dotted box illustrated in Fig. 27 (a) is illustrated.

[0353] Referring to (a) and (b) of FIG. 27, the turn intervals of T1-T6 are all different, and the turn width of each turn may also be different.

[0354] Referring to (b) of Fig. 27, the turn width (tw1) of T1 may be different from the turn width (tw2) of T2 to the turn width (tw6) of T6.

[0355] The turn-to-turn interval (dn12) between T1 and T2 may be different from the turn-to-turn interval (dn23) between T2 and T3 or the turn-to-turn interval (dn56) between T5 and T6. That is, dn12 > dn23 > dn34 > dn45 > dn56.

[0356] The turn width (tw1) of T1 may be a relatively larger value than the turn width (tw2) of T2 or the turn width (tw6) of T6. That is, it can be seen that tw1 > tw2 > tw3 > tw4 > tw5 > tw6.

[0357] Meanwhile, even if the turn width and the turn spacing of each turn constituting the PCB working coil in (b) of Fig. 27 are different, the number of unit coils constituting one turn may or may not be the same for each turn.

[0358] The PCB working coil according to each embodiment illustrated in FIGS. 25 to 27 has the advantage of further reducing heat generation compared to, for example, the PCB working coil illustrated in FIG. 22. Furthermore, the reduction in heat generation ensures stable operation of the PCB working coil, which ultimately contributes to stable operation of the cooking appliance.

[0359] In addition, the PCB working coil according to each embodiment illustrated in FIGS. 25 to 27 can increase the operating time of the PCB working coil by reducing the heat generation phenomenon compared to the PCB working coil illustrated in FIG. 22, which can ultimately contribute to extending the service life of the cooking appliance.

[0360] The embodiments of FIGS. 25 to 27 described above are based on the contents of FIG. 23 (a), but an embodiment based on the contents of FIG. 23 (b) is also possible, and such contents may also be included in the present disclosure.

[0361] Figures 28 to 29 illustrate embodiments with reference to the graph of Figure 24 (a).

[0362] FIGS. 28 to 29 are drawings illustrating a PCB working coil in which turns are arranged according to embodiments of the present disclosure.

[0363] In Fig. 28 (a), a top view of a PCB coil consisting of six turns (T1-T6) is shown, and in Fig. 28 (b), a cross-sectional view of the turns within the dotted box shown in Fig. 28 (a) is shown.

[0364] Referring to (a) and (b) of Fig. 28, a PCB working coil configured with reference to the graph shown in (a) of Fig. 24 can be represented.

[0365] Here, it is assumed that the turn width (tw) of each turn (T1-T6) constituting the PCB working coil is the same.

[0366] As shown in the graph in (a) of Fig. 24, as the number of turns increases, the turn-to-turn interval (dn) can change, as shown in (b) of Fig. 28. At this time, in Fig. 23 (a), as the number of turns increases, the turn-to-turn interval (dn) decreases linearly, whereas in Fig. 24 (a), as the number of turns increases, the turn-to-turn interval (dn) decreases nonlinearly. Here, nonlinearity can indicate that there exist both sections where the turn-to-turn interval (dn) changes and sections where it does not change, as described above.

[0367] Referring to (a) of FIG. 24 and (b) of FIG. 28, the turn-to-turn interval (dn12) between T1 and T2 may be the same as the turn-to-turn interval (dn23) between T2 and T3. Therefore, dn12 and dn23 may correspond to the previously described unchanging intervals. However, dn12 and dn23 may have relatively larger values ​​compared to the turn-to-turn interval (dn34) between T3 and T4, the turn-to-turn interval (dn45) between T4 and T5, and the turn-to-turn interval (dn56) between T5 and T6.

[0368] The next changing interval is that dn34 may have a relatively larger value than dn45 and dn56. And dn45 may have a relatively larger value than dn56.

[0369] Next, in Fig. 29, there is an embodiment of adjusting both the turn width of each turn and the turn spacing in the PCB working coil with reference to (a) of Fig. 24.

[0370] In (a) of Fig. 29, a PCB working coil having six turns (T1-T6) is similarly illustrated, and in (b) of Fig. 29, a cross-sectional view of the turns within the dotted box illustrated in (a) of Fig. 29 is illustrated.

[0371] Referring to (a) and (b) of FIG. 29, not only are the turn intervals (dn) of T1-T6 not all the same, but the turn widths of T1-T6 may also not be the same.

[0372] Referring to (b) of Fig. 29, the turn width (tw1) of T1 may be different from the turn width (tw2) of T3 to the turn width (tw6) of T6.

[0373] Referring to (b) of Fig. 29, the turn width (tw1) of T1 is the same as the turn width (tw2) of T2, but may be different from the turn width (tw3) of T3 to the turn width (tw6) of T6.

[0374] tw3 may be different from tw4 to tw6. tw4 may be different from tw5 to tw6. tw5 may be different from tw6.

[0375] Although (a) of Fig. 24 defines the turn-to-turn interval relative to the number of turns, the turn-to-turn interval in (a) of Fig. 24 can also be changed to the turn width. In other words, the turn-to-turn interval relative to the number of turns can also decrease nonlinearly.

[0376] The above contents can be applied identically or similarly to the graphs of (a) to (b) of Fig. 23 or (b) of Fig. 24.

[0377] Referring to (a) of FIG. 24 and (b) of FIG. 29, the turn-to-turn interval (dn) between T1-T6 may be the same as the turn-to-turn interval (dn) of T1-T6 illustrated in (b) of FIG. 28 described above.

[0378] Even if the turn width and the turn spacing of each turn constituting the PCB working coil in (b) of Fig. 29 are different, the number of unit coils constituting each turn may or may not be the same.

[0379] The PCB working coil according to each embodiment illustrated in FIGS. 28 to 29 can further reduce the heat generation phenomenon compared to, for example, the PCB working coil illustrated in FIG. 22, thereby ensuring stable operation of the PCB working coil, which ultimately has the advantage of contributing to improved stability of the cooking appliance (1).

[0380] In addition, the PCB working coil according to each embodiment illustrated in FIGS. 28 to 29 has the advantage of further reducing the heat generation phenomenon compared to, for example, the PCB working coil illustrated in FIG. 22, thereby increasing the operating time of the PCB working coil, which ultimately contributes to extending the lifespan of the cooking appliance (1).

[0381] Meanwhile, although not illustrated, the opposite of what is illustrated in FIGS. 28 and 29 is also possible. For example, the embodiments of FIGS. 28 and 29 may be configured to have a PCB working coil that is the opposite of what is illustrated based on the content of FIG. 24 (b), and such content may also be included in the present disclosure.

[0382] If the aforementioned drawings 25 to 29 were explained in terms of PCB working coil units, the following drawings 30 to 36 explain using as an example one of the turns among the plurality of turns constituting the PCB working coil.

[0383] Fig. 30 is a drawing illustrating the internal configuration of a turn in the PCB working coil (WC) (500) of Fig. 22.

[0384] The internal configuration of each turn constituting the PCB working coil may or may not be identical. However, for convenience of explanation, in this disclosure, it is assumed that the internal configuration of the turns constituting the PCB working coil is identical.

[0385] For convenience of explanation, two turns (Tn and Tn+1, where n is a natural number) are shown in Fig. 30.

[0386] At this time, as mentioned above, it is assumed that the internal configurations of Tn and Tn+1 are identical. Therefore, in Fig. 30, the n+1-th turn, Tn+1, has the same internal configuration as the n-th turn, Tn, so only a portion of it is disclosed and the rest is omitted.

[0387] A single turn (e.g., Tn) may have a multi-layer structure. In Fig. 30, only two layers (L1, L2) are illustrated for convenience of explanation, but the present invention is not limited thereto.

[0388] Meanwhile, each layer of the turn (Tn) may be connected to each other through a via hole, but is not limited thereto.

[0389] Each layer of the turn (Tn) can be configured to include multiple unit coils (e.g., L1 (s1-s8), L2 (s9-s15)).

[0390] For convenience of explanation, the following examples are described using one layer (L1) as an example. However, the present disclosure is not limited thereto, and the same or similar content applied to L1 may also be applied or applied to other layers, such as L2.

[0391] In this disclosure, the interval between turns (e.g., between Tn and Tn+1) is referred to as an inter-turn interval.

[0392] In Fig. 30, a total of eight unit coils (s1-s8) can be arranged on the L1 layer. The spacing between unit coils is described by naming it ds. The width (or width) of one unit coil is described by naming it ws.

[0393] Figures 31 to 34 are drawings illustrating unit coils constituting one layer of one turn of Figure 30.

[0394] In Fig. 30, it is exemplified that the spacing (ds) between the unit coils constituting the L1 layer of Tn is uniform (or fixed, constant, etc.), and the width (ws) of each unit coil is also the same.

[0395] Meanwhile, in Figures 31 and 32, unit coils (s1-s8) constituting the L1 layer of Tn are illustrated.

[0396] Referring to Figures 31 and 32, for example, it can be seen that the widths (ws) of the eight unit coils are all the same, but the spacing (ds) between the unit coils is not uniform.

[0397] At this time, both Figs. 31 and 32 can represent the L1 layer of the same turn (e.g., T1, etc.).

[0398] Alternatively, FIGS. 31 and 32 may each represent the L1 layer of different turns. In this case, for example, FIG. 14 may represent the L1 layer of T1, and FIG. 15 may represent the L1 layer of T6. It should be apparent that other turns may be used instead of the aforementioned T1 and T6.

[0399] First, referring to Fig. 14, the spacing between unit coils constituting the L1 layer of Tn may be different from each other.

[0400] Specifically, the interval (ds1) between s1 and s2 is different from the interval (ds2) between s2 and s3. In this case, ds1 may be greater than ds2. The interval (ds2) between s2 and s3 is different from the interval (ds3) between s3 and s4. In this case, ds2 may be greater than ds3. The interval (ds3) between s3 and s4 is different from the interval (ds4) between s4 and s5. In this case, ds3 may be greater than ds4. The interval (ds4) between s4 and s5 is different from the interval (ds5) between s5 and s6. In this case, ds4 may be greater than ds5. The interval (ds5) between s5 and s6 is different from the interval (ds6) between s6 and s7. At this time, ds5 can be greater than ds6. The interval between s6 and s7 (ds6) is different from the interval between s7 and s8 (ds7). At this time, ds6 can be greater than ds7.

[0401] The gap between s7 and s8 (ds7) may be the smallest value among the gaps between unit coils (ds) in the L1 layer. Conversely, the gap between s1 and s2 (ds1) may be the largest value among the gaps between unit coils (ds) in the L1 layer.

[0402] In the above, the spacing between any two unit coils may not match the spacing between the other two unit coils.

[0403] Alternatively, the spacing between any two unit coils may match the spacing between any two other unit coils.

[0404] Figure 32 shows the opposite case of Figure 31.

[0405] That is, referring to Fig. 32, the spacing between unit coils constituting the L1 layer of Tn may be different from each other.

[0406] Specifically, the interval (ds1) between s1 and s2 is different from the interval (ds2) between s2 and s3. In this case, ds1 may be smaller than ds2. The interval (ds2) between s2 and s3 is different from the interval (ds3) between s3 and s4. In this case, ds2 may be smaller than ds3. The interval (ds3) between s3 and s4 is different from the interval (ds4) between s4 and s5. In this case, ds3 may be smaller than ds4. The interval (ds4) between s4 and s5 is different from the interval (ds5) between s5 and s6. In this case, ds4 may be smaller than ds5. The interval (ds5) between s5 and s6 is different from the interval (ds6) between s6 and s7. At this time, ds5 may be smaller than ds6. The interval between s6 and s7 (ds6) is different from the interval between s7 and s8 (ds7). At this time, ds6 may be smaller than ds7.

[0407] The gap (ds1) between s1 and s2 may be the smallest value among the gaps (ds) between unit coils in the L1 layer. Conversely, the gap (ds7) between s7 and s8 may be the largest value among the gaps (ds) between unit coils in the L1 layer.

[0408] In the above, the spacing between any two unit coils may not match the spacing between the other two unit coils.

[0409] Alternatively, the spacing between any two unit coils may match the spacing between any two other unit coils.

[0410] Referring to Figures 33 and 34, for example, it can be seen that the widths (ws) of the eight unit coils are all the same, but the spacing (ds) between the unit coils is not uniform.

[0411] At this time, both Figs. 33 and 34 can represent the L1 layer of the same turn (e.g., T1, etc.).

[0412] Alternatively, FIGS. 33 and 34 may each represent the L1 layer of different turns. In this case, for example, FIG. 16 may represent the L1 layer of T1, and FIG. 17 may represent the L1 layer of T6. It should be apparent that other turns may be used instead of the aforementioned T1 and T6.

[0413] First, referring to Fig. 16, the spacing between unit coils (ds1-ds7) constituting the L1 layer of Tn can be the same.

[0414] However, the width (ws) of each unit coil may be different.

[0415] Specifically, the width of s1 (ws1) is different from the width of s2 (ws2). In this case, ws1 may be larger than ws2. The width of s2 (ws2) is different from the width of s3 (ws3). In this case, ws2 may be larger than ws3. The width of s3 (ws3) is different from the width of s4 (ws4). In this case, ws3 may be larger than ws4. The width of s4 (ws4) is different from the width of s5 (ws5). In this case, ws4 may be larger than ws5. The width of s5 (ws5) is different from the width of s6 (ws6). In this case, ws5 may be larger than ws6. The width of s6 (ws6) is different from the width of s7 (ws7). In this case, ws6 may be larger than ws7. The width of s7 (ws7) is different from the width of s8 (ws8). In this case, ws7 can be larger than ws8.

[0416] The width of s8 (ws8) can be the smallest value among the widths (ws) of the unit coils in the L1 layer. Conversely, the width of s1 (ws1) can be the largest value among the widths (ws) of the unit coils in the L1 layer.

[0417] In the above, the width (ws) of any unit coil may not match the width (ws) of the other unit coils.

[0418] Alternatively, the width (ws) of any unit coil may match the width (ws) of at least one of the remaining unit coils.

[0419] Fig. 34 is a case in which the spacing (ds) between the two unit coils is also different from Fig. 33. That is, in Fig. 34, not only is the spacing (ds) between the two unit coils different as shown in Fig. 28, but also the width (ws) of each unit coil is different as shown in Fig. 33.

[0420] That is, referring to Fig. 34, the spacing (ds) between unit coils constituting the L1 layer of Tn and the width (ws) of each unit coil may be different from each other.

[0421] Specifically, the interval (ds1) between s1 and s2 is different from the interval (ds2) between s2 and s3. In this case, ds1 may be smaller than ds2. The interval (ds2) between s2 and s3 is different from the interval (ds3) between s3 and s4. In this case, ds2 may be smaller than ds3. The interval (ds3) between s3 and s4 is different from the interval (ds4) between s4 and s5. In this case, ds3 may be smaller than ds4. The interval (ds4) between s4 and s5 is different from the interval (ds5) between s5 and s6. In this case, ds4 may be smaller than ds5. The interval (ds5) between s5 and s6 is different from the interval (ds6) between s6 and s7. At this time, ds5 may be smaller than ds6. The interval between s6 and s7 (ds6) is different from the interval between s7 and s8 (ds7). At this time, ds6 may be smaller than ds7.

[0422] The gap (ds7) between s7 and s8 may be the smallest value among the gaps (ds) between unit coils in the L1 layer. Conversely, the gap (ds1) between s1 and s2 may be the largest value among the gaps (ds) between unit coils in the L1 layer.

[0423] In the above, the spacing between any two unit coils may not match the spacing between the other two unit coils.

[0424] Alternatively, the spacing between any two unit coils may match the spacing between any two other unit coils.

[0425] Also, the width of s1 (ws1) is different from the width of s2 (ws2). In this case, ws1 may be larger than ws2. The width of s2 (ws2) is different from the width of s3 (ws3). In this case, ws2 may be larger than ws3. The width of s3 (ws3) is different from the width of s4 (ws4). In this case, ws3 may be larger than ws4. The width of s4 (ws4) is different from the width of s5 (ws5). In this case, ws4 may be larger than ws5. The width of s5 (ws5) is different from the width of s6 (ws6). In this case, ws5 may be larger than ws6. The width of s6 (ws6) is different from the width of s7 (ws7). In this case, ws6 may be larger than ws7. The width of s7 (ws7) is different from the width of s8 (ws8). In this case, ws7 can be larger than ws8.

[0426] The width of s8 (ws8) can be the smallest value among the widths (ws) of the unit coils in the L1 layer. Conversely, the width of s1 (ws1) can be the largest value among the widths (ws) of the unit coils in the L1 layer.

[0427] In the above, the width (ws) of any unit coil may not match the width (ws) of the other unit coils.

[0428] Alternatively, the width (ws) of any unit coil may match the width (ws) of at least one of the remaining unit coils.

[0429] Figures 35 and 36 are drawings illustrating the unit coil configuration for the multi-layer of Figure 30.

[0430] In Figures 31 to 34, the configuration of unit coils belonging to the L1 layer of the multi-layer of Tn illustrated in Figure 30 is disclosed.

[0431] The disclosures of FIGS. 31 to 34 described above can be applied identically or similarly to other layers than the L1 layer of Tn illustrated in FIG. 30.

[0432] In other words, the configuration of the unit coils of each layer constituting one turn (Tn) can be the same.

[0433] In another embodiment, the configuration of the unit coils of each layer constituting one turn (Tn) may not be identical. For example, at least one layer among the plurality of layers constituting one turn (Tn) may not have the same configuration of the unit coils as at least one other layer. Conversely, at least one layer among the plurality of layers constituting one turn (Tn) may have the same configuration of the unit coils as at least one other layer.

[0434] For convenience, the L1 and L2 layers of T1 are illustrated in FIGS. 35 and 36.

[0435] First, referring to Fig. 35, the configuration (arrangement, spacing, width, etc.) of the unit coils (s1-s8) of the L1 layer and the configuration of the unit coils (s9-s15) of the L2 layer are identical.

[0436] On the other hand, referring to Fig. 36, the configuration (arrangement, spacing, width, etc.) of the unit coils (s1-s8) of the L1 layer and the configuration of the unit coils (s9-s15) of the L2 layer are not identical.

[0437] Figures 35 and 36 are examples to explain the sameness or difference in the configuration between each layer in a multi-layer, and are not limited to the detailed configuration (arrangement, spacing, width, etc.) of each layer.

[0438] FIG. 37 is a drawing illustrating an interval between turns in oz according to one embodiment of the present disclosure.

[0439] Figure 37 (a) can show that the spacing between patterns can be determined for each oz (i.e., PCB thickness), and accordingly, the spacing between turns of each pattern can also be determined according to oz.

[0440] According to the present disclosure, the turn-to-turn spacing can be at least twice the conventional manufacturing limit, compared to the minimum spacing determined by oz.

[0441] Meanwhile, (b) of Fig. 37 explains that when going inward from the outer turn based on the center point, the minimum interval of oz can be increased by a multiple of the minimum interval.

[0442] For example, if the spacing of the outer turns based on the center point is 0.3 mm for 3 oz, the spacing of the inner turns can be designed to increase by the product of the turns and the spacing.

[0443] However, this is only an example and may not be limited to the contents of the above-described Figure 37.

[0444] FIG. 38 is a diagram illustrating a change in resistance versus the number of turns according to one embodiment of the present disclosure.

[0445] Resistance can be designed to vary linearly or non-linearly with the number of turns.

[0446] Figure 38 is a drawing illustrating that the turn and turn spacing can be increased and the cross-sectional areas of the inner and outer windings can be made asymmetrical.

[0447] Figure 38 (a) illustrates that the pattern width of the inner turn increases as it moves outward. Since the resistance of the outer turn is greater than that of the inner turn, the resistance can be reduced, and thus, improvement in pattern loss can be expected.

[0448] And, (b) to (c) of Fig. 38 are drawings showing the internal turn and the external turn and the resistance changing nonlinearly, for example, in a step form.

[0449] Meanwhile, (d) of Fig. 38 is a drawing illustrating a reduction in the pattern width of the inner turn toward the outside. Referring to (d) of Fig. 38, since the internal magnetic field can be lowered, improvement in heat generation of the inner PCB pattern can be expected (reduction in resistance of the inner turn).

[0450] However, the numbers in (a) to (d) of Fig. 38 are arbitrarily selected for convenience of explanation and are not limited thereto.

[0451] FIG. 39 is a drawing illustrating a case in which the number of twists is varied when changing from an inner turn to an outer turn according to one embodiment of the present disclosure.

[0452] Figure 39 (a) illustrates a case where twisting is not applied so that magnetic fields overlap in adjacent windings, while Figure 39 (b) illustrates a case where twisting is applied so that magnetic field overlap is reduced by minimizing the area of ​​twist with adjacent windings.

[0453] Figure 39 (c) is a drawing showing that the number of twists can be varied for internal and external turns.

[0454] As shown in (d) of Fig. 39, the number of twists may change nonlinearly as the number of turns increases. For example, the number of twists may decrease up to a certain number of turns, but may not change after that number of turns and may remain constant. Although the decrease is shown as a linear decrease in Fig. 39 (d), it is not necessarily limited to this and may also decrease nonlinearly.

[0455] In Fig. 39 (e), as opposed to the aforementioned Fig. 39 (d), the number of twists changes nonlinearly as the number of turns increases. For example, the number of twists may not change until a certain number of turns is reached, but may increase after that number of turns. In this case, although Fig. 39 (e) shows a case of linear increase, it is not necessarily limited to this and may increase nonlinearly.

[0456] The present disclosure may also include embodiments in which the contents illustrated in FIGS. 22 to 36 described above are combined within a combinable range.

[0457] Meanwhile, the present disclosure may adjust the number of strands in one turn constituting one PCB working coil by referring to at least one drawing among the contents illustrated in FIGS. 22 to 36 described above and the technical idea included in the description thereof. Here, the number of strands may represent the number of unit coils. For example, the number of strands of Tn may be m (where m is a natural number), and the number of strands of Tn+1 may be m+k (where k is a natural number). K may or may not have a linear value depending on the change in n. Meanwhile, the number of strands of Tn may be m (where m is a natural number), and the number of strands of Tn+1 may be mp (where p is a natural number). P may or may not have a linear value depending on the change in n.

[0458] Similarly, if a turn consists of multiple layers, the above-described steps can also apply to each layer. That is, even if they belong to the same turn, the composition of each layer may or may not be identical.

[0459] In addition, depending on the strand count adjustment mentioned above, it may affect other factors.

[0460] In addition, when a plurality of working coils are included in the cooking appliance (1) to form a burner, at least one of the plurality of working coils may be a PCB working coil. In this case, the PCB working coil may be configured according to at least one of the above-described FIGS. 22 to 39.

[0461] Meanwhile, if the cooking appliance (1) includes multiple working coils each forming a burner, at least two of the multiple working coils may be PCB working coils. In this case, each PCB working coil may be configured according to at least one of the aforementioned FIGS. 22 to 39. However, each PCB working coil may not have the same configuration.

[0462] Meanwhile, if the cooking appliance (1) includes multiple PCB working coils, the sizes of each PCB working coil may be different. For example, the distance between the center point of each PCB working coil and the outermost turns may be different.

[0463] The above description is merely an example of the technical idea of ​​the present disclosure, and those skilled in the art to which the present disclosure pertains will be able to make various modifications and variations without departing from the essential characteristics of the present disclosure.

[0464] Accordingly, the embodiments disclosed in the present disclosure are intended to illustrate rather than limit the technical idea of ​​the present disclosure, and the scope of the technical idea of ​​the present disclosure is not limited by these embodiments.

[0465] The scope of protection of the present disclosure should be interpreted by the claims below, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the rights of the present disclosure.

[0466] The present disclosure relates to a cooking appliance including a working coil that maximizes heating efficiency and a cooking appliance that heats a heated object using a PCB working coil, and has industrial applicability.

Claims

1. The upper part where the heated object is placed; A plurality of working coils for heating the above-mentioned object; An inverter that applies current to each of the above working coils; and Including a controller that controls the operation of the inverter so that the object to be heated is heated through each of the working coils, At least one of the above working coils, A PCB working coil including multiple turns, but with unequal spacing between the turns. Cooking appliances.

2. In claim 1, The spacing between turns of the above PCB working coil increases as it gets closer to the center point of the above PCB working coil. Cooking appliances.

3. In claim 1, The above PCB working coil is, It is divided into multiple sections from the center point to the outermost section, and each section includes at least one turn. Cooking appliances.

4. In claim 3, The above plurality of sections includes a first section in which the interval between turns does not change and a second section in which the interval between turns changes. Cooking appliances.

5. In claim 4, The above first section is, Compared to the second section above, the gap between turns is large. Cooking appliances.

6. In claim 5, The above first section is, A section closer to the center point than the second section above, Cooking appliances.

7. In claim 1, The width of each turn of the above PCB working coil is not uniform. Cooking appliances.

8. In claim 7, The width of each turn of the above PCB working coil is wider the closer it is to the center point. Cooking appliances.

9. In claim 1, Each turn of the above PCB working coil includes a plurality of unit coils, and the spacing between the unit coils of the plurality of unit coils included in the turn is not uniform depending on the position of the turn. Cooking appliances.

10. In claim 9, The closer the position of the above turn is to the center point of the PCB working coil, the wider the gap between the unit coils of the plurality of unit coils included in the turn. Cooking appliances.

11. In claim 1, Each turn of the above PCB working coil includes multiple unit coils, and the number of unit coils included in the turn is different depending on the position of the turn. Cooking appliances.

12. In claim 11, The number of unit coils included in each turn of the above PCB working coil increases as it gets closer to the center point of the above PCB working coil. Cooking appliances.

13. In claim 1, Each turn of the above PCB working coil includes multiple unit coils, and the width of each unit coil included in the turn is different depending on the position of the turn. Cooking appliances.

14. In claim 13, The width of the unit coil included in each turn of the above PCB working coil is wider the closer it is to the center point of the above PCB working coil. Cooking appliances.

15. In claim 1, The above-mentioned working coil includes a plurality of layers of PCB working coils, and the PCB working coils of each layer have at least one different from each other among the interval between turns, the turn width, the interval between unit coils included in each turn, and the number. Cooking appliances.

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