Induction heater and control method therefor

Abstract

An induction heater, according to one aspect of the disclosed invention, comprises: a first heating unit comprising one heating coil; a second heating unit comprising an inner heating coil and an outer heating coil; and a control unit for controlling the operations of the first heating unit and the second heating unit, wherein the maximum output frequency of the one heating coil may be set to be higher than the maximum output frequency of the inner heating coil operating alone, and lower than the maximum output frequency of the inner heating coil and the outer heating coil operating together.

Description

Induction heating device and its control method

[0001] The disclosed invention relates to an induction heating device and a control method thereof, and more particularly, to an induction heating device including dual heating coils and a control method thereof.

[0002] In general, an induction heating device is a cooking device that heats and cooks food using the principles of induction heating. An induction heating device comprises a cooking plate on which a cooking vessel is placed and a heating coil that generates a magnetic field when current is applied.

[0003] When current is applied to the heating coil, a magnetic field is generated, inducing a secondary current in the cooking vessel. This, in turn, generates Joule heat due to the vessel's own resistance. Consequently, the cooking vessel is heated by the high-frequency current, and the food contained within is cooked.

[0004] These induction heating devices use the cooking vessel itself as a heat source, so they have the advantage of high heat transfer, no generation of harmful gases, and no risk of fire compared to gas ranges or kerosene stoves that burn fossil fuels and heat the cooking vessel through the combustion heat.

[0005] When multiple heating coils of such induction heating devices are operated simultaneously, noise may be generated due to different output frequencies.

[0006] One aspect of the disclosed invention provides an induction heating device and a control method thereof capable of reducing noise by setting the maximum output frequency of each heating coil differently and matching the maximum output frequency through duty ratio control during simultaneous operation.

[0007] The technical problems to be achieved in this document are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0008] An induction heating device according to one aspect of the disclosed invention comprises: a first heating unit including one heating coil; a second heating unit including an internal heating coil and an external heating coil; and a control unit controlling operations of the first heating unit and the second heating unit; wherein a maximum output frequency of the one heating coil can be set to be higher than a maximum output frequency in case of single operation of the internal heating coil and lower than a maximum output frequency in case of simultaneous operation of the internal heating coil and the external heating coil.

[0009] Figure 1 illustrates the appearance of an induction heating device according to one embodiment.

[0010] Figures 2 and 3 are drawings illustrating the heating principle of an induction heating device according to one embodiment.

[0011] Figure 4 illustrates an example of a resonant circuit according to one embodiment.

[0012] FIG. 5 is a diagram illustrating an induction heating device including dual heating coils according to one embodiment.

[0013] FIG. 6 is a diagram illustrating the principle of driving a dual heating coil according to one embodiment.

[0014] FIG. 7 is a drawing showing that the maximum output frequency of each heating coil is set differently according to one embodiment.

[0015] Fig. 8 is a drawing showing a control block diagram of an induction heating device according to one embodiment.

[0016] FIG. 9 is a diagram showing matching the maximum output frequency through duty ratio control according to one embodiment.

[0017] FIG. 10 is a drawing for explaining matching different maximum output frequencies of each heating coil according to one embodiment.

[0018] Figures 11 and 12 are flowcharts showing a control method of an induction heating device according to one embodiment.

[0019] The embodiments described in this specification and the configurations illustrated in the drawings are merely preferred examples of the disclosed invention, and there may be various modified examples that can replace the embodiments and drawings of this specification at the time of filing of this application.

[0020] Additionally, the same reference numbers or symbols presented in each drawing of this specification represent parts or components that perform substantially the same function.

[0021] In addition, the terminology used in this specification is used to describe embodiments and is not intended to limit and / or restrict the disclosed invention. The singular expression includes plural expressions unless the context clearly indicates otherwise. In this specification, the terms "comprises" or "has" and the like are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0022] Additionally, in this specification, when it is said that a configuration is “connected” or “coupled” with another configuration, this includes not only cases where it is directly connected or coupled, but also cases where it is indirectly connected or coupled.

[0023] Additionally, terms including ordinal numbers such as “first,” “second,” etc. used herein may be used to describe various components, but the components are not limited by the terms, and the terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term “and / or” includes any combination of a plurality of related listed items or any item among a plurality of related listed items.

[0024] Hereinafter, an embodiment according to the present invention will be described with reference to the attached drawings.

[0025] FIG. 1 illustrates the appearance of an induction heating device according to one embodiment, and FIGS. 2 and 3 are drawings for showing the heating principle of the induction heating device according to one embodiment.

[0026] FIG. 1 is a top view of an induction heating device (1) according to one embodiment. As shown in FIG. 1, the induction heating device (1) according to one embodiment may include a plate (110) provided on an upper portion of a main body (101), a cooking zone (111, 112, 113) formed on the plate (110), and a user interface (120, 130) functioning as an input / output device. As an example, the plate (110) may be made of ceramic.

[0027] Cooking zones (111, 112, 113) indicate the positions where cooking containers are placed, and may be represented by a circular shape as indicated by drawing 111 to guide proper placement of cooking containers, or by straight boundary lines as indicated by drawing 112, 113.

[0028] However, the shapes described above are merely examples of shapes for indicating the cooking zone (111, 112, 113), and can be applied to the embodiment of the induction heating device (1) even if it is not circular or straight, as long as it can guide the user to the location of the cooking zone.

[0029] In addition, although the example illustrates a case where three cooking zones are formed on the plate (110), the embodiment of the induction heating device (1) is not limited to this. It is also possible to form only one cooking zone, or it is also possible to form four or more cooking zones.

[0030] A display (120) and an input device (130) may be provided in one area of ​​the plate (110). The display (120) may include a display device such as an LCD or an LED, and the input device (130) may include at least one of various input devices such as a touch pad, a button, a jog shuttle, etc. Alternatively, the display (120) and the input device (130) may implement a touch screen.

[0031] In the present example, a case in which a display (120) and an input device (130) are provided at positions spaced apart from the cooking zones (111, 112, 113) on a plate (110) is exemplified. However, the arrangement of FIG. 1 is merely an example applicable to an induction heating device (1), and it is also possible for the display (120) or the input device (130) to be provided at a position other than the plate (110), such as the front of the induction heating device (1).

[0032] Referring to FIGS. 2 and 3 together, a heating coil (240) may be placed on the lower portion of the plate (110) to heat a container (10) placed on the plate (110). For convenience of explanation, only one heating coil (240) is illustrated in FIGS. 2 and 3, but the number of heating coils (240) may be provided corresponding to the number of cooking zones.

[0033] In the case where there are three cooking zones (111, 112, 113) as in the example of Fig. 1, three heating coils (240) can also be provided, and each heating coil (240) can be placed below each cooking zone (111, 112, 113).

[0034] The heating coil (240) can be connected to a resonant circuit (2, see FIG. 4) described later, and a high-frequency current can be applied from the resonant circuit (2). For example, the frequency of the high-frequency current can be 20 kHz to 35 kHz.

[0035] When a high-frequency current is supplied to the heating coil (240), magnetic lines of force (ML) can be formed in the heating coil (240). When a container (10) having resistance is positioned within the range of the magnetic lines of force (ML), the magnetic lines of force (ML) around the heating coil (240) pass through the bottom of the container (10) and generate an eddy current, i.e., an eddy current (EC), in the form of an eddy current according to the law of electromagnetic induction.

[0036] Heat can be generated in the container (10) by the interaction of these eddy currents (EC) and the electrical resistance of the container (10), and the food inside the container (10) can be heated by the generated heat.

[0037] In an induction heating device (1) like this, since the container (10) itself acts as a heat source, a metal having a certain level of resistance or higher, such as iron, stainless steel, or nickel, can be used as the material of the container (10).

[0038] Meanwhile, the specifications of the heating coil (240) may be designed differently depending on the rated voltage of the country where the induction heating device (1) is sold.

[0039] Figure 4 illustrates an example of a resonant circuit according to one embodiment.

[0040] Referring to Fig. 4, the resonant circuit (2) may include a power supply (20).

[0041] The power supply unit (20) may include a power supply (ES) and a rectifier (210).

[0042] The power source (ES) is an AC power source (ES) and can supply power (ES) corresponding to the rated voltage.

[0043] The rectifier (210) can convert the AC voltage supplied from the power source (ES) into DC voltage.

[0044] To this end, the rectifier (210) may include a bridge rectifier circuit composed of a plurality of diodes. For example, the bridge rectifier circuit may include four diodes. The diodes may form diode pairs in which two diodes are connected in series, and the two diode pairs may be connected in parallel with each other. The bridge diode may convert an AC voltage whose polarity changes over time into a voltage whose polarity is constant, and may convert an AC current whose direction changes over time into a current whose direction is constant.

[0045] In addition, the rectifier (210) may include a DC link capacitor. The DC link capacitor may convert a voltage whose magnitude changes over time into a DC voltage of a constant magnitude. The DC link capacitor may maintain the converted DC voltage and provide it to the inverter circuit (SW1-1, SW1-2). At this time, the inverter circuit (SW1-1, SW1-2) may include a first switching element (SW1-1) of the first switching unit and a second switching element (SW1-2) of the first switching unit.

[0046] The first switching element (SW1-1) of the first switching unit and the second switching element (SW1-2) of the first switching unit can operate complementarily to each other to cause an alternating current to flow to the heating coil (240).

[0047] The first switching element (SW1-1) of the first switching unit and the second switching element (SW1-2) of the first switching unit may be implemented as a three-terminal semiconductor element switch having a fast response speed in order to be turned on / off at high speed. For example, the first switching element (SW1-1) of the first switching unit and the second switching element (SW1-2) of the first switching unit may be a bipolar junction transistor (BJT), a metal-oxide-semiconductor field effect transistor (MOSFET), an insulated gate bipolar transistor (IGBT), or a thyristor.

[0048] The first switching element (SW1-1) of the first switching unit and the second switching element (SW1-2) of the first switching unit can be turned on / off by a switch driving signal. At this time, the switch driving signal can be provided by the control unit (150), and the control unit (150) can supply high-frequency alternating current to the heating coil (240) by alternately turning on / off the first switching element (SW1-1) of the first switching unit and the second switching element (SW1-2) of the first switching unit.

[0049] The resonant circuit (2) may further include a filter that removes noise components contained in the power supplied from the power source (ES). The filter is composed of a transformer and a capacitor and can remove noise mixed in the power supplied from the power source (ES), and can provide AC power with the noise removed to the rectifier (210).

[0050] FIG. 5 is a drawing showing an induction heating device including dual heating coils according to one embodiment, and FIG. 6 is a drawing showing a principle of driving dual heating coils according to one embodiment.

[0051] The dual heating coil (250) can operate in an operation mode including a dual mode for heating a first area and a single mode for heating a second area narrower than the first area depending on the size of the bottom surface of the object to be heated. For example, the dual heating coil (250) can include an inner heating coil (251) and an outer heating coil (252), and the dual heating coil (250) can operate in a single mode for heating only the inner area by the inner heating coil (251) and a dual mode for heating both the inner area and the outer area by the inner heating coil (251) and the outer heating coil (252). The operation mode of the dual heating coil (250) can be determined by the control unit (150).

[0052] The induction heating device (1) can detect a heated object placed on a cooking zone, and based on the size of the bottom surface of the detected heated object, determine the operating mode of the dual heating coil (250) as either a dual mode or a single mode. Alternatively, the device can be controlled to perform one of the dual mode and the single mode operating modes based on input from a user or the like.

[0053] The dual heating coil (250) may include an inner heating coil (251) located in the inner region and an outer heating coil (252) located in the outer region. The inner region and the outer region may be donut-shaped regions with a common center at a single point. A gap may be included between the inner region and the outer region. However, the dual heating coil (250) region is not limited thereto, and there may not be a gap between the inner region and the outer region.

[0054] The internal heating coil (251) and the external heating coil (252) can be connected in parallel. For example, the first node (Nd1) of the internal heating coil (251) can be connected to the third node (Nd3) of the external heating coil (252), and the second node (Nd2) of the internal heating coil (251) can be connected to the fourth node (Nd4) of the external heating coil (252) through a dual switching unit (SW).

[0055] The control unit (150) can supply power to the internal heating coil (251) and / or the external heating coil (252). For example, when performing operation in a dual mode, the control unit (150) can turn on the dual switching unit so that the internal heating coil (251) and the external heating coil (252) operate together. Additionally, when performing operation in a single mode, the control unit (150) can turn off the dual switching unit so that only the internal heating coil (251) operates.

[0056] In this way, the induction heating device (1) may include a dual heating coil (250) including an internal heating coil (251) and an external heating coil (252).

[0057] Below, design changes and control operations for noise reduction in an induction heating device (1) including such a dual heating coil (250) are described.

[0058] FIG. 7 is a drawing showing that the maximum output frequency of each heating coil is set differently according to one embodiment.

[0059] As described above, when multiple heating coils included in the induction heating device (1) operate simultaneously, noise may be generated due to different output frequencies.

[0060] In the present invention, a case is described where a first heating unit (230) including one heating coil (240) and a second heating unit (250) including an internal heating coil (251) and an external heating coil (252) operate simultaneously. Here, the second heating unit (250) may include a dual heating coil (250) including the internal heating coil (251) and the external heating coil (252) described above.

[0061] Referring to (a) of Fig. 7, the maximum output frequency (f1) of one heating coil can be set lower than the maximum output frequency (f2) of the internal heating coil during single operation and the maximum output frequency (f3) of the internal heating coil and the external heating coil during simultaneous operation. In addition, the maximum output frequency (f2) of the internal heating coil during single operation can be set lower than the maximum output frequency (f3) of the internal heating coil and the external heating coil during simultaneous operation.

[0062] Since noise may be generated when multiple heating coils operate at different output frequencies, a relatively higher frequency can be made to match a lower frequency through a method such as duty ratio control.

[0063] However, since the method of reducing the frequency through duty ratio control is usually limited to a range of about 3 kHz, if the difference between frequencies exceeds 3 kHz, it may be difficult to match the frequencies even through duty ratio control.

[0064] When the maximum output frequency of each heating coil is set as in (a) of Fig. 7, when one heating coil (240) and an internal heating coil (251) operate simultaneously, the maximum output frequency (f2) of a single operation of the internal heating coil can be reduced by the maximum output frequency (f1) of one heating coil through duty control.

[0065] However, since the maximum output frequency (f3) when the internal heating coil and the external heating coil operate simultaneously is higher than the maximum output frequency (f2) when the internal heating coil operates alone, when one heating coil (240), the internal heating coil (251), and the external heating coil (252) operate simultaneously, the difference between the maximum output frequency (f3) when the internal heating coil and the external heating coil operate simultaneously and the maximum output frequency (f1) of one heating coil may exceed 3 kHz, making it difficult to match the frequencies even through duty ratio control.

[0066] Accordingly, one embodiment of the present invention can set the maximum output frequency (f1) of one heating coil to be higher than the maximum output frequency (f2) of the internal heating coil during single operation, and lower than the maximum output frequency (f3) of the internal heating coil and the external heating coil during simultaneous operation, as shown in (b) of FIG. 7.

[0067] By setting the maximum output frequency of each heating coil in this way, as described later, when one heating coil (240) and the internal heating coil (251) operate simultaneously, the maximum output frequency (f1) of one heating coil can be reduced by the maximum output frequency (f2) of the internal heating coil when it operates alone, and when one heating coil (240), the internal heating coil (251), and the external heating coil (252) operate simultaneously, the maximum output frequency (f3) of the internal heating coil and the external heating coil when it operates simultaneously can be reduced by the maximum output frequency (f1) of one heating coil.

[0068] As described above, the method of reducing the frequency through duty ratio control is usually limited to a range of about 3 kHz, so the difference between the maximum output frequency (f1) of one heating coil and the maximum output frequency (f2) when the internal heating coil operates alone may be 3 kHz or less. In addition, the difference between the maximum output frequency (f1) of one heating coil and the maximum output frequency (f3) when the internal and external heating coils operate simultaneously may also be 3 kHz or less.

[0069] By setting the maximum output frequencies of multiple heating coils differently, noise reduction through duty ratio control during simultaneous operation can be facilitated. Below, an operation for aligning the maximum output frequencies to reduce noise when heating coils with different maximum output frequencies are operated simultaneously is described.

[0070] Fig. 8 is a drawing showing a control block diagram of an induction heating device according to one embodiment.

[0071] An induction heating device (1) may include a first heating unit (230) including one heating coil (240), a second heating unit (250) including an internal heating coil (251) and an external heating coil (252), and may further include a control unit (150) that controls the operation of the first heating unit (230) and the heating unit. The control unit (150) may include a processor and a memory. Here, the second heating unit (250) may include a dual heating coil (250) including an internal heating coil (251) and an external heating coil (252) as mentioned above.

[0072] The control unit (150) may include a memory (152) that stores a control program and control data for controlling the first heating unit (230) and the second heating unit (250), and at least one processor (151) that generates a control signal according to the control program and control data stored in the memory. The memory (152) and the processor (151) may be provided integrally or separately.

[0073] The memory (152) can store programs and data for controlling the first heating unit (230) and the second heating unit (250).

[0074] The memory (152) may include volatile memory such as Static Random Access Memory (S-RAM) and Dynamic Random Access Memory (D-RAP) for temporarily storing data. In addition, the memory (152) may include nonvolatile memory such as Read Only Memory (ROM), Erasable Programmable Read Only Memory (EPROM), and Electrically Erasable Programmable Read Only Memory (EEPROM) for long-term storage of data.

[0075] The processor (151) may include various logic circuits and operation circuits, process data according to a program provided from memory, and generate a control signal according to the processing result.

[0076] The control unit (150) can change the maximum output frequency (f1) of one heating coil so that the maximum output frequency (f1) of one heating coil and the maximum output frequency (f2) of the internal heating coil in single operation are the same when one heating coil (240) and the internal heating coil (251) operate simultaneously (when one heating coil (240) and the dual heating coils (250) operate simultaneously in the single mode described above).

[0077] That is, since the maximum output frequency (f1) of one heating coil is set higher than the maximum output frequency (f2) of the internal heating coil during single operation, as shown in (b) of Fig. 7, the maximum output frequency (f1) of one heating coil can be changed to match the maximum output frequency (f2) of the internal heating coil during single operation.

[0078] In addition, the control unit (150) can change the maximum output frequency during simultaneous operation of the internal heating coil (251) and the external heating coil (252) so that the maximum output frequency (f1) of one heating coil and the maximum output frequency (f3) during simultaneous operation of the internal heating coil and the external heating coil are the same when one heating coil (240) and the internal heating coil (251) and the external heating coil (252) operate simultaneously (when one heating coil (240) and the dual heating coil (250) operate simultaneously in the aforementioned dual mode).

[0079] That is, since the maximum output frequency (f3) is set higher than the maximum output frequency (f1) of one heating coil when the internal heating coil and the external heating coil operate simultaneously as shown in (b) of Fig. 7, the maximum output frequency (f3) can be changed to match the maximum output frequency (f1) of one heating coil when the internal heating coil and the external heating coil operate simultaneously.

[0080] FIG. 9 is a drawing showing matching the maximum output frequency through duty ratio control according to one embodiment, and FIG. 10 is a drawing for explaining matching the different maximum output frequencies of each heating coil according to one embodiment.

[0081] The induction heating device (1) may further include a first switching unit (SW1) connected to the first heating unit (230) and a second switching unit (SW2) connected to the second heating unit (250).

[0082] The switching unit can be turned on / off according to a switching drive signal. That is, the control unit (150) can supply high-frequency alternating current to the first heating unit (230) by alternately turning on / off the first switching element (SW1-1) of the first switching unit and the second switching element (SW1-2) of the first switching unit.

[0083] In addition, the control unit (150) can supply high-frequency alternating current to the second heating unit (250) by alternately turning on / off the first switching element (SW2-1) of the second switching unit and the second switching element (SW2-2) of the second switching unit.

[0084] As described above, the control unit (150) can match the maximum output frequency through duty ratio control that adjusts the on / off ratio of the switching unit.

[0085] That is, when one heating coil (240) and an internal heating coil (251) operate simultaneously, the control unit (150) can perform duty ratio control of the first switching unit (SW1) so that the maximum output frequency (f1) of one heating coil and the maximum output frequency (f2) of the internal heating coil during single operation become the same, thereby changing the maximum output frequency (f1) of one heating coil.

[0086] In addition, the control unit (150) can perform duty ratio control of the second switching unit (SW2) so that when one heating coil (240), an internal heating coil (251), and an external heating coil (252) operate simultaneously, the maximum output frequency (f1) of one heating coil and the maximum output frequency (f3) when the internal heating coil and the external heating coil operate simultaneously become the same, and accordingly, the maximum output frequency (f3) when the internal heating coil and the external heating coil operate simultaneously can be changed.

[0087] FIG. 9 illustrates an example of a case in which duty ratio control of the second switching unit (SW2) is performed. As shown in (a) of FIG. 9, before duty ratio control, the maximum output frequency (f1) of one heating coil and the maximum output frequency (f3) when the internal heating coil and the external heating coil are operated simultaneously are different from each other. However, through duty ratio control, as shown in (b) of FIG. 9, the maximum output frequency (f3) when the internal heating coil and the external heating coil are operated simultaneously is reduced to match the maximum output frequency (f1) of one heating coil.

[0088] That is, as shown in FIG. 10 (a), when one heating coil (240) and an internal heating coil (251) operate simultaneously, the maximum output frequency (f1) of one heating coil is reduced to match the maximum output frequency (f2) of the internal heating coil during single operation, and as shown in FIG. 10 (b), when one heating coil (240), an internal heating coil (251), and an external heating coil (252) operate simultaneously, the maximum output frequency (f3) of the internal heating coil and the external heating coil during simultaneous operation can be reduced to match the maximum output frequency (f1) of one heating coil.

[0089] According to this duty ratio control, the maximum output frequency can be matched even when multiple heating coils are operated simultaneously, thereby reducing noise.

[0090] Figures 11 and 12 are flowcharts showing a control method of an induction heating device according to one embodiment.

[0091] When one heating coil (240) and an internal heating coil (251) operate simultaneously (when one heating coil (240) and a dual heating coil (250) operate simultaneously in the single mode described above, 1101), the maximum output frequency of one heating coil (240) can be changed so that the maximum output frequency (f1) of one heating coil and the maximum output frequency (f2) of the internal heating coil in single operation are the same (1103).

[0092] That is, since the maximum output frequency (f1) of one heating coil is set higher than the maximum output frequency (f2) of the internal heating coil during single operation, as shown in (b) of Fig. 7, the maximum output frequency (f1) of one heating coil can be changed to match the maximum output frequency (f2) of the internal heating coil during single operation.

[0093] In this case, the duty ratio control of the first switching unit (SW1) can be performed, and accordingly, the maximum output frequency (f1) of one heating coil can be changed.

[0094] In addition, when one heating coil (240) and an internal heating coil (251) and an external heating coil (252) operate simultaneously (when one heating coil (240) and a dual heating coil (250) operate simultaneously in the aforementioned dual mode, 1201), the maximum output frequency when the internal heating coil (251) and the external heating coil (252) operate simultaneously can be changed so that the maximum output frequency (f1) of one heating coil and the maximum output frequency (f3) when the internal heating coil and the external heating coil operate simultaneously are the same (1203).

[0095] That is, since the maximum output frequency (f3) is set higher than the maximum output frequency (f1) of one heating coil when the internal heating coil and the external heating coil operate simultaneously as shown in (b) of Fig. 7, the maximum output frequency (f3) can be changed to match the maximum output frequency (f1) of one heating coil when the internal heating coil and the external heating coil operate simultaneously.

[0096] In this case, the duty ratio control of the second switching unit (SW2) can be performed, and accordingly, the maximum output frequency (f3) can be changed when the internal heating coil and the external heating coil are operated simultaneously.

[0097] An induction heating device according to one embodiment includes a first heating unit including one heating coil; a second heating unit including an internal heating coil and an external heating coil; and a control unit controlling operations of the first heating unit and the second heating unit, wherein a maximum output frequency of the one heating coil may be set to be higher than a maximum output frequency when the internal heating coil is operated single-handedly and lower than a maximum output frequency when the internal heating coil and the external heating coil are operated simultaneously.

[0098] According to the present disclosure, noise can be reduced by setting the maximum output frequency of each heating coil differently and matching the maximum output frequency through duty ratio control during simultaneous operation.

[0099] The control unit can change the maximum output frequency of the one heating coil so that, when the one heating coil and the internal heating coil operate simultaneously, the maximum output frequency of the one heating coil and the maximum output frequency of the internal heating coil during a single operation are the same.

[0100] The device further includes a first switching unit connected to the first heating unit, and the control unit can change the maximum output frequency of the one heating coil through duty ratio control of the first switching unit.

[0101] When the one heating coil and the internal heating coil and the external heating coil operate simultaneously, the maximum output frequency of the one heating coil and the maximum output frequency of the internal heating coil and the external heating coil when operating simultaneously can be changed so that the maximum output frequency of the one heating coil and the maximum output frequency of the internal heating coil and the external heating coil when operating simultaneously are the same.

[0102] The second switching unit is further included, and the control unit can change the maximum output frequency during simultaneous operation of the internal heating coil and the external heating coil through duty ratio control of the second switching unit.

[0103] The difference between the maximum output frequency of the above one heating coil and the maximum output frequency of the internal heating coil during a single operation may be 3 kHz or less.

[0104] The difference between the maximum output frequency of the above one heating coil and the maximum output frequency when the inner heating coil and the outer heating coil are operated simultaneously may be 3 kHz or less.

[0105] A control method of an induction heating device according to one embodiment comprises: a first heating unit including one heating coil; and a second heating unit including an internal heating coil and an external heating coil; wherein a maximum output frequency of the one heating coil is set to be higher than a maximum output frequency of the internal heating coil in single operation and lower than a maximum output frequency of the internal heating coil and the external heating coil in simultaneous operation; and when the one heating coil and the internal heating coil operate simultaneously, the maximum output frequency of the one heating coil is changed so that the maximum output frequency of the one heating coil and the maximum output frequency of the internal heating coil in single operation are the same.

[0106] The device may further include a first switching unit connected to the first heating unit, and changing the maximum output frequency of the one heating coil may include changing the maximum output frequency of the one heating coil through duty ratio control of the first switching unit.

[0107] When the one heating coil and the internal heating coil and the external heating coil operate simultaneously, the maximum output frequency of the one heating coil and the maximum output frequency of the internal heating coil and the external heating coil when operating simultaneously may be changed so that the maximum output frequency of the one heating coil and the maximum output frequency of the internal heating coil and the external heating coil when operating simultaneously are the same.

[0108] The second switching unit connected to the second heating unit may further include, and changing the maximum output frequency during simultaneous operation of the internal heating coil and the external heating coil may include changing the maximum output frequency during simultaneous operation of the internal heating coil and the external heating coil through duty ratio control of the second switching unit.

[0109] The difference between the maximum output frequency of the above one heating coil and the maximum output frequency of the internal heating coil during a single operation may be 3 kHz or less.

[0110] The difference between the maximum output frequency of the above one heating coil and the maximum output frequency when the inner heating coil and the outer heating coil are operated simultaneously may be 3 kHz or less.

[0111] According to the disclosed invention, noise can be reduced by setting the maximum output frequency of each heating coil differently and matching the maximum output frequency through duty ratio control during simultaneous operation.

[0112] Meanwhile, the disclosed embodiments may be implemented in the form of a recording medium storing computer-executable instructions. The instructions may be stored in the form of program code, and when executed by a processor, may generate program modules to perform the operations of the disclosed embodiments. The recording medium may be implemented as a computer-readable recording medium.

[0113] Computer-readable storage media include all types of storage media that store instructions that can be deciphered by a computer. Examples include read-only memory (ROM), random access memory (RAM), magnetic tape, magnetic disks, flash memory, and optical data storage devices.

[0114] The disclosed embodiments have been described with reference to the attached drawings as described above. Those skilled in the art will understand that the present invention can be implemented in forms other than the disclosed embodiments without altering the technical spirit or essential features of the present invention. The disclosed embodiments are illustrative and should not be construed as limiting.

Claims

1. A first heating unit comprising one heating coil; a second heating unit including an inner heating coil and an outer heating coil; and A control unit for controlling the operation of the first heating unit and the second heating unit is included; The maximum output frequency during operation of the above one heating coil is: An induction heating device having a frequency higher than the maximum output frequency when the inner heating coil is operated alone and lower than the maximum output frequency when the inner heating coil and the outer heating coil are operated simultaneously.

2. In paragraph 1, The above control unit, When the above one heating coil and the internal heating coil operate simultaneously, An induction heating device that changes the maximum output frequency of one heating coil so that the maximum output frequency of the one heating coil and the maximum output frequency of a single operation of the internal heating coil are the same.

3. In paragraph 2, Further comprising a first switching unit connected to the first heating unit; The above control unit, An induction heating device that changes the maximum output frequency of one heating coil by controlling the duty ratio of the first switching unit.

4. In paragraph 1, When the above one heating coil and the inner heating coil and the outer heating coil operate simultaneously, An induction heating device that changes the maximum output frequency of the inner heating coil and the outer heating coil during simultaneous operation so that the maximum output frequency of the one heating coil and the maximum output frequency of the inner heating coil and the outer heating coil during simultaneous operation are the same.

5. In paragraph 4, Further comprising a second switching unit connected to the second heating unit; The above control unit, An induction heating device that changes the maximum output frequency when the internal heating coil and the external heating coil operate simultaneously by controlling the duty ratio of the second switching unit.

6. In paragraph 1, An induction heating device wherein the difference between the maximum output frequency of the above one heating coil and the maximum output frequency of the internal heating coil during single operation is 3 kHz or less.

7. In paragraph 1, An induction heating device wherein the difference between the maximum output frequency of the above one heating coil and the maximum output frequency when the inner heating coil and the outer heating coil are operated simultaneously is 3 kHz or less.

8. In paragraph 1, The second heating unit comprises a dual heating coil including the inner heating coil and the outer heating coil, An induction heating device wherein the inner heating coil can operate independently of the outer heating coil or simultaneously with the outer heating coil.

9. In paragraph 8, The above second heating unit, An induction heating device further comprising a gap between the inner heating coil and the outer heating coil.

10. A method for controlling an induction heating device comprising a first heating unit including one heating coil; and a second heating unit including an inner heating coil and an outer heating coil; The maximum output frequency of the above one heating coil is set higher than the maximum output frequency of the single operation of the inner heating coil and lower than the maximum output frequency of the simultaneous operation of the inner heating coil and the outer heating coil. When the above one heating coil and the internal heating coil operate simultaneously, A control method of an induction heating device, comprising: changing the maximum output frequency of one heating coil so that the maximum output frequency of the one heating coil and the maximum output frequency of a single operation of the internal heating coil are the same.

11. In Article 10, Further comprising a first switching unit connected to the first heating unit; Changing the maximum output frequency of the above one heating coil, A control method for an induction heating device, comprising changing the maximum output frequency of one heating coil by controlling the duty ratio of the first switching unit.

12. In paragraph 11, When the above one heating coil and the inner heating coil and the outer heating coil operate simultaneously, A control method for an induction heating device further comprising: changing the maximum output frequency of the one heating coil and the maximum output frequency of the simultaneous operation of the inner heating coil and the outer heating coil so that the maximum output frequency of the one heating coil and the maximum output frequency of the simultaneous operation of the inner heating coil and the outer heating coil are the same; 13. In paragraph 12, Further comprising a second switching unit connected to the second heating unit; Changing the maximum output frequency during simultaneous operation of the internal heating coil and the external heating coil is A control method for an induction heating device, comprising changing the maximum output frequency during simultaneous operation of the internal heating coil and the external heating coil by controlling the duty ratio of the second switching unit.

14. In paragraph 10, A control method for an induction heating device, wherein the difference between the maximum output frequency of the above-mentioned one heating coil and the maximum output frequency of the above-mentioned single operation of the internal heating coil is 3 kHz or less.

15. In paragraph 10, A control method for an induction heating device, wherein the difference between the maximum output frequency of the above one heating coil and the maximum output frequency when the inner heating coil and the outer heating coil are operated simultaneously is 3 kHz or less.

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