Patent Publication Number: US-2021186249-A1

Title: Wireless induction heating cooker having improved cooking uniformity

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0170124, filed in on Dec. 18, 2019, the disclosure of which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to a wireless induction heating cooker that can provide cooking uniformity even when the wireless induction heating cooker is partially misaligned on a working coil of an induction heating apparatus. 
     BACKGROUND 
     Various types of cooking devices may use a method of wireless induction heating. For example, an induction heating apparatus may heat an object subject to cooking using a magnetic field rather than heating the object subject using heat generated in the heating apparatus. 
     In some examples, the method for heating an object using a magnetic field may be carried out by an induction heating apparatus and a cooker. Specifically, based on electromagnetic induction between the induction heating apparatus and the cooker, power may be transmitted from the induction heating apparatus to the cooker, and the power transmitted to the cooker may heat and cook an object in the cooker. 
     In some cases, a working coil in the induction heating apparatus and a power reception coil in the cooker may be magnetically coupled with a high coupling coefficient. The working coil and the power reception coil may be aligned for induction heating. 
       FIG. 1A  and  FIG. 1B  illustrate an example of an operation method of an induction heating cooker in related art. 
     Referring to  FIG. 1A , in the induction heating cooker  1  of the related art includes a cooking unit  10  and a power unit  20 . An internal pot  60  is accommodated in an internal pot accommodation part  14  in the cooking unit  10 , and an induction heating coil  15  for heating the internal pot  60  is provided at a lower portion of the internal pot accommodation part  14 . A power reception coil  16 , which receives power to be supplied to the induction heating coil  15  from the power unit  20 , is provided on a bottom surface of a main body  12  of the cooking unit  10 . 
     The power unit  20  includes a power supply coil  23  disposed to face the power reception coil  16  for a magnetic coupling with the power reception coil  16 . In this case, to align the power reception coil  16  and the power supply coil  23 , a main body lock  17  that fixes the cooking unit  10  and the power unit  20  mutually is provided at the main body  12  of the cooking unit  10 . 
     Referring to  FIG. 1B , the induction heating cooker  1  of the related art includes the cooking unit  100  where the power reception coil  16  is fixedly disposed, and a power unit  20 C where the power supply coil  23  is fixedly disposed are physically fixed through the main body lock  17  to align the power supply coil  23  serving as a working coil and the power reception coil  16  serving as a receiving coil. 
     In some cases, the cooking unit  10  may be operated only on the power unit  20  having a specific structure. For instance, when the cooking unit  10  is operated on another induction heating apparatus other than the power unit  20 , alignment between the power reception coil  16  and the working coil may not be ensured. Thus, cooking performance may be deteriorated. 
     In some cases, an induction heating apparatus and a wireless induction heating cooker may be separately manufactured. Accordingly, a user may align the wireless induction heating cooker at a proper position on the induction heating apparatus manually to cook an object. 
     In some cases, the wireless induction heating cooker may be partially aligned or misaligned on the working coil the induction heating apparatus. 
     In some case, due to the misalignment between the apparatuses, the object in the wireless induction heating cooker may not be completely cooked or may be overheated depending on its position. In some cases, a deterioration of cooking uniformity may cause dissatisfaction to users. 
     SUMMARY 
     The present disclosure is directed to a wireless induction heating cooker that may provide cooking uniformity even when the wireless induction heating cooker is partially misaligned on a working coil of an induction heating apparatus. 
     The present disclosure is also directed to a wireless induction heating cooker that may heat even a lateral surface of an internal pot using a magnetic field generated in a working coil of an induction heating apparatus. 
     The present disclosure is also directed to a wireless induction heating cooker that may use a magnetic field, generated in an area with a small amount of heat delivered to an internal pot, to heat a lateral surface of the internal pot. 
     Aspects of the present disclosure are not limited to the above-described ones. Additionally, other aspects and advantages that have not been mentioned may be clearly understood from the following description and may be more clearly understood from implementations. Further, it will be understood that the aspects and advantages of the present disclosure may be realized via means and combinations thereof that are described in the appended claims. 
     According to one aspect of the subject matter described in this application, a wireless induction heating cooker is configured to operate on an induction heating apparatus. The wireless induction heating cooker includes a main body, an internal pot configured to be disposed in the main body, a plurality of receiving coils disposed at a bottom surface of the main body and arranged along a circumferential direction of the internal pot, and a plurality of lateral surface heating coils spaced apart from the bottom surface of the main body and arranged along a lateral surface of the internal pot. Each of the plurality of lateral surface heating coils is connected to one of the plurality of receiving coils that is disposed at an opposite side with respect to a reference line passing through the bottom surface of the main body. 
     Implementations according to this aspect may include one or more of the following features. For example, 2. the plurality of receiving coils may include a first receiving coil and a second receiving coil, and the plurality of lateral surface heating coils may include a first lateral surface heating coil connected to the first receiving coil and disposed at an opposite side of the first receiving coil with respect to the reference line, and a second lateral surface heating coil connected to the second receiving coil and disposed at an opposite side of the second receiving coil with respect to the reference line. 
     In some implementations, the plurality of receiving coils may be configured to induce electric currents based on a magnetic field being generated in a working coil of the induction heating apparatus. In some implementations, each of the plurality of receiving coils may be configured to supply induced electric current to a corresponding heating coil among the plurality of lateral surface heating coils, and the plurality of lateral surface heating coils may be configured to heat the lateral surface of the internal pot based on the induced electric current. 
     In some implementations, the wireless induction heating cooker may further include a metallic plate disposed on the lateral surface of the internal pot and configured to be heated by a magnetic field generated in the plurality of receiving coils and by the plurality of lateral surface heating coils. 
     In some implementations, the wireless induction heating cooker may further include a resonance capacitor that connects one of the plurality of receiving coils to one of the plurality of lateral surface heating coils. In some examples, centers of the plurality of receiving coils may be arranged on the bottom surface of the main body along the circumferential direction of the internal pot, and centers of the plurality of lateral surface heating coils may be disposed in a plane parallel to the bottom surface of the main body and are arranged along the circumferential direction of the internal pot. 
     In some examples, vertical distances between the bottom surface of the main body and the centers of the plurality of lateral surface heating coils may be equal to one another. 
     In some implementations, the reference line may be a vertical line through a center of the internal pot. Radial distances from the vertical line to centers of the plurality of receiving coils may be equal to one another, and radial distances from the vertical line to centers of the plurality of lateral surface heating coils may be equal to one another. 
     In some implementations, the plurality of receiving coils may be arranged on the bottom surface of the main body that faces a working coil of the induction heating apparatus. 
     In some implementations, the internal pot may include a round portion that extends upward from a bottom surface of the internal pot, and the round portion may have a lower end that is connected to the bottom surface of the internal pot and that defines a first radius of the internal pot, and an upper end that is disposed vertically above the lower end and that defines a second radius of the internal pot that is different from the first radius. The plurality of receiving coils may be disposed radially outside the lower end of the round portion. 
     In some implementations, the internal pot may include a round portion that defines a first radius of the internal pot and a second radius of the internal pot, and the plurality of receiving coils may face a lower part of the round portion of the internal pot. In some examples, the second radius of the internal pot may be greater than the first radius of the internal pot, and a distance between the reference line and an outer edge of each of the plurality of receiving coils may be greater than the second radius of the internal pot. In some examples, a center of one of the plurality of receiving coils and a center of one of the plurality of lateral surface heating coils connected to the one of the plurality of receiving coils may be disposed on a line that crosses the reference line. 
     In some implementations, the plurality of lateral surface heating coils are vertically arranged on the lateral surface of the internal pot. In some implementations, each of the plurality of lateral surface heating coils may be disposed on a plane that is inclined with respect to the bottom surface of the main body, and each of the plurality of lateral surface heating coils has a lower edge facing the bottom surface of the main body and an upper edge disposed vertically above the lower edge. A radial distance between the reference line and the lower edge may be less than a radial distance between the reference line and the upper edge. 
     In some implementations, the plurality of lateral surface heating coils may be disposed concavely along a round portion of the internal pot. 
     In some implementations, where the reference line is a vertical line through a center of the internal pot, central angles defined about the vertical line between two adjacent receiving coils among the plurality of receiving coils may be equal to one another, and central angles defined about the vertical line between two adjacent lateral surface heating coils among the plurality of lateral surface heating coils may be equal to one another. 
     In some implementations, the plurality of receiving coils may be arranged symmetrically with respect to the reference line, and the plurality of lateral surface heating coils may be arranged symmetrically with respect to the reference line. In some implementations, each of the plurality of receiving coils may have a flat shape parallel to the bottom surface of the main body, and each of the plurality of lateral surface heating coils may have a convex shape that protrudes outward relative to the lateral surface of the internal pot. 
     In some implementations, a plurality of receiving coils may be arranged along a circumferential direction of an internal pot and face a working coil of an induction heating apparatus. The plurality of receiving coils may be placed to face a plurality of lateral surface heating coils that are arranged along a lateral surface of the internal pot, thereby providing cooking uniformity even when a wireless induction heating cooker is partially aligned or misaligned on the working coil of the induction heating apparatus. 
     In some implementations, a plurality of receiving coils may be arranged to face a working coil of an induction heating apparatus and may be respectively connected to a plurality of lateral surface heating coils arranged along a lateral surface of an internal pot, thereby heating the lateral surface of the internal pot using a magnetic field generated in the working coil of the induction heating apparatus. 
     In some implementations, a plurality of receiving coils may be arranged to face a working coil of an induction heating apparatus and may be placed at a lower portion of a round area of an internal pot. The plurality of receiving coils may be respectively connected to a plurality of lateral surface heating coils arranged along a lateral surface of the internal pot, thereby utilizing a magnetic field generated in an area with a small amount of heat delivered to the internal pot to heat a lateral surface of the internal pot. 
     The wireless induction heating cooker may provide cooking uniformity even when a wireless induction heating cooker is partially aligned or misaligned on a working coil of an induction heating apparatus, thereby ensuring quality cooking uniformity regardless of a position of the wireless induction heating cooker and improving user convenience without strictly requiring a user to align the wireless induction heating cooker. 
     The wireless induction heating cooker may heat even a lateral surface of an internal pot using a magnetic field generated in a working coil of an induction heating apparatus, thereby forming a plurality of paths for heat delivery with a single heat source and ensuring temperature uniformity based on height of the internal pot. 
     The wireless induction heating cooker may use a magnetic field generated in an area with a small amount of heat delivered to an internal pot to heat a lateral surface of the internal pot, thereby efficiently using a magnetic field generated in a working coil to heat a lower portion and the lateral surface of the internal pot. 
     Detailed effects of the present disclosure are described together with the above-described effects in the detailed description of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  and  FIG. 1B  are views illustrating examples of an operation method of an induction heating cooker in related art. 
         FIG. 2  is a view illustrating an example of a wireless induction heating cooker operating on an induction heating apparatus. 
         FIG. 3  is an exploded view illustrating the wireless induction heating cooker in  FIG. 2 . 
         FIG. 4  is a circuit diagram illustrating an example of a receiving coil that is magnetically connected with a working coil of an induction heating apparatus, and an example of a later surface heating coil that is connected to the receiving coil. 
         FIG. 5  is a view illustrating an example arrangement of a receiving coil and a lateral surface heating coil corresponding to the receiving coil. 
         FIG. 6A  and  FIG. 6B  are views illustrating an example of an internal pot surrounded by a plurality of lateral surface heating coils and a plurality of receiving coils. 
         FIG. 7A  and  FIG. 7B  are views illustrating example positions of example receiving coils and example lateral surface heating coils. 
         FIG. 8A  and  FIG. 8B  are views illustrating example receiving coils disposed at a lower portion of an internal pot including a round portion. 
         FIG. 9A  and  FIG. 9B  are views illustrating an example of a lateral surface heating coil disposed on a lateral surface of an internal pot including a round portion. 
         FIG. 10  is a view illustrating an example of a wireless induction heating cooker that is partially aligned with a working coil. 
     
    
    
     DETAILED DESCRIPTION 
     The above-described aspects, features and advantages are specifically described with reference to the accompanying drawings hereunder such that one having ordinary skill in the art to which the present disclosure pertains may easily implement the technical spirit of the disclosure. Below, one or more implementations of the present disclosure are specifically described with reference to the accompanying drawings. Throughout the drawings, identical reference numerals denote identical or similar components. 
     Below, an example wireless induction heating cooker is described with reference to  FIGS. 2 to 9 . 
       FIG. 2  illustrates an example of a wireless induction heating cooker configured to operate on an induction heating apparatus, and  FIG. 3  is an exploded view illustrating the wireless induction heating cooker in  FIG. 2 . 
       FIG. 4  is a circuit diagram illustrating an example receiving coil that is magnetically connected with a working coil of an induction heating apparatus, and an example later surface heating coil connected to the receiving coil, and  FIG. 5  is a view illustrating an example of an arrangement of a receiving coil and a lateral surface heating coil corresponding to the receiving coil. 
       FIG. 6A  and  FIG. 6B  illustrate an example internal pot surrounded by a plurality of lateral surface heating coils and disposed on a plurality of receiving coils. 
       FIG. 7A  and  FIG. 7B  illustrate example positions of example receiving coils and example lateral surface heating coils. 
       FIG. 8A  and  FIG. 8B  illustrate an example receiving coil disposed at a lower portion of an internal pot including a round portion, and  FIG. 9A  and  FIG. 9B  illustrate an example lateral surface heating coil disposed on a lateral surface of an internal pot including a round portion. 
       FIG. 10  illustrates an example of a wireless induction heating cooker that is partially aligned with a working coil. 
     Referring to  FIG. 2 , a wireless induction heating cooker  100  may operate on an induction heating apparatus. For example, the wireless induction heating cooker  100  may operate on an upper plate  200  of any induction heating apparatus provided with a working coil  210  in a state of being on a perpendicular line of the working coil  210 . 
     Electric currents may flow through the working coil  210  by control of the induction heating apparatus. Accordingly, a magnetic field may be generated in the working coil  210 . The magnetic field generated in the working coil  210  may heat an internal pot  130  in the wireless induction heating cooker  100 . 
     In some implementations, referring to  FIGS. 2 and 3 , the wireless induction heating cooker  100  may include a main body  110 , a lid  120 , an internal pot  130 , a metallic plate  130   a , a receiving coil  140 , and a lateral surface heating coil  150 . The lid  120  may include a steam discharge module  121 , a noise reduction module  122 , a pressure weight  123 , and a control module  124 . 
     The wireless induction heating cooker  100  in  FIGS. 2 and 3  is provided as one example, and components of the wireless induction heating cooker  100  are not limited to those of the implementation in  FIGS. 2 and 3 . When necessary, some components may be added, modified or removed. 
     For example, the main body  110 , which is or includes a case that supports a lower portion and a lateral portion of the wireless induction heating cooker  100 , may have a cylinder shape in which an upper portion is opened and a lower portion is sealed by a bottom surface  110   b . The process of cooking may be performed in the main body  110 . Specifically, the main body  110  may include an internal pot  130 , a metallic plate  130   a  that wraps the internal pot  130 , and a receiving coil  140  and a lateral surface heating coil  150  for heating the internal pot  130 , therein. Various types of grain such as rice may be heated and cooked in the internal pot  130 . 
     In some implementations, the lid  120  may be or include a case configured to seal an upper portion of the wireless induction heating cooker  100 . The lid  120  may be coupled to the opened upper surface of the main body  110 . An upper surface of the lid  120  may be sealed by a lid cover  120   c . In this case, the lid  120  may be coupled to the upper surface of the main body  110  such that the lid  120  is opened and closed with respect to the upper surface of the main body  110 . Specifically, the lid  120  may be hinge-coupled to the upper surface of the main body  110  such that the lid  120  is optionally opened and closed, or may be attached and detached by a coupler (e.g., a coupling ring) provided on the upper surface of the main body  110 . 
     In some implementations, the lid  120  may include a control module  124  that may control some or entire operations of the wireless induction heating cooker  100 . The control module  124  may include a printed circuit board (PCB) including a plurality of integrated circuits (IC). 
     In some implementations, the lid  120  may include a pressure weight  123  for constantly maintaining pressure in the wireless induction heating cooker  100 , and a steam discharge module  121  (e.g., a solenoid valve) for discharging steam in the wireless induction heating cooker  100  outwards on the basis of a control signal provided by the control module  124 . Furthermore, the lid  120  may include a noise reduction module  122  that includes a sound absorption member for reducing noise when steam is discharged. 
     The internal pot  130  may be stored in the main body  110  and may be heated by a magnetic field generated in the working coil  210  of the induction heating apparatus. The internal pot  130  may have a shape corresponding to a shape of an inner space of the main body  110 . For example, in case the main body  110  has a cylinder shape, the internal pot  130  may have a cylinder shape in which an upper surface is opened. 
     When the wireless induction heating cooker  100  is placed on an upper portion of the induction heating apparatus, the working coil  210  and a lower surface of the internal pot  130  and may be placed to face each other with the bottom surface  110   b  of the main body  110  therebetween. A magnetic field generated in the working coil  210  may induce electric currents to the internal pot  130 , and Joule&#39;s heat may be generated in the internal pot  130  by the induced currents. 
     For generation of induced currents, the internal pot  130  may be made of any material having magnetic properties. The internal pot  130 , for example, may be made of cast iron including iron (Fe), or clad in which iron (Fe) and stainless steel and the like are welded. 
     The internal pot  130  may include a metallic plate  130   a  that is heated by a magnetic field generated in the below-described receiving coil  140  and lateral surface heating coil  150 , on an outer surface thereof. 
     In case the internal pot  130  is made of a material (e.g., aluminum (Al), copper (Cu) and the like) that has almost no magnetic property or no magnetic property while having high thermal conductivity to improve efficiency of thermal conduction, almost no induced currents or no induced currents may be generated by a magnetic field in the internal pot  130 . 
     In this case, even though the internal pot  130  has high thermal conductivity, heat is not generated in the internal pot  130 . Accordingly, the internal pot  130  may include a metallic plate  130   a  on the outer surface thereof to deliver heat to the internal pot  130 . 
     The metallic plate  130   a  may be made of a material having a magnetic property. Additionally, the metallic plate  130   a  may be implemented as a component separate from the internal pot  130  and may be stored in the main body  110 . The metallic plate  130   a  may coat the outer surface of the internal pot  130  through the process of metal spraying and the like. Accordingly, heat may be generated at the metallic plate  130   a  by a magnetic field, and the heat generated at the metallic plate  130   a  may be delivered to the internal pot  130 . 
     A plurality of receiving coils  140  may be arranged in parallel on the bottom surface  110   b  of the main body  110  along a circumferential direction of the internal pot  130 . The circumferential direction is a direction defined along a perimeter. In case the internal pot  130  has a cylinder shape, the circumferential direction may be a direction of a circumference of the cylinder. In case the internal pot  130  has a polyprism shape, the circumferential direction may be a direction of a perimeter of the polyprism. Referring to  FIG. 3 , the plurality of receiving coils  140  may be arranged in parallel on the bottom surface  110   b  of the main body  110  along a circumferential direction of the internal pot  130 . 
     Electric currents may be induced to the plurality of receiving coils  140  by a magnetic field generated in the working coil  210  of the induction heating apparatus. To this end, the plurality of receiving coils  140  may be flatly arranged on the bottom surface  110   b  of the main body  110  to face the working coil  210 . 
     Referring back to  FIGS. 2 and 3 , the plurality of receiving coils  140  may be implemented as a circular flat plate-shaped coil, and each receiving coil  140  may be disposed in parallel with the working coil  210  to face the working coil  210 . A magnetic field generated in the working coil  210  may be interlinked with each receiving coil  140 , and electric currents may be induced to the receiving coil  140  by the magnetic field interlinked with the receiving coil  140 . 
     The electric currents induced to the receiving coil  140  may heat the internal pot  130 . Specifically, when electric currents are induced to the receiving coil  140 , a magnetic field may be generated in the receiving coil  140 . The magnetic field generated in the receiving coil  140  may induce electric currents to the internal pot  130 , and Joule&#39;s heat may be generated in the internal pot  130  by the induced currents. 
     That is, the internal pot  130 , as described above, may be heated by a magnetic field generated in the working coil  210  or by a magnetic field generated in the receiving coil  140 . 
     A plurality of lateral surface heating coils  150  may be connected respectively to the plurality of receiving coils  140  and may be arrange in parallel along a lateral surface of the internal pot  130  respectively on the opposite side of each receiving coil  140  connected to each of them. Referring to  FIG. 2 , the plurality of lateral surface heating coils  150  may be arranged in parallel on a circumferential surface of the internal pot  130 . 
     In some examples, the lateral surface heating coils  150  may be disposed in a virtual plane that is parallel to a bottom surface of the main body  110 . For example, centers of the lateral surface heating coils  150  may be disposed in the virtual plane, and vertical distances between the bottom surface of the main body  110  and the centers may be equal to one another. 
     In some implementations, a pair of coils including the receiving coil  140  and the lateral surface heating coil  150  that are connected to each other. In other words, any one receiving coil of the plurality of receiving coils  140  may be electrically connected to one lateral surface heating coil of the plurality of lateral surface heating coils  150 . 
     Referring to  FIG. 4 , each of the plurality of receiving coils  140  and each of the plurality of lateral surface heating coils  150  may be connected through a resonance capacitor (Cr) to constitute a resonance circuit (or a tank circuit) (RC). 
     One end of each receiving coil  140  and one end of each lateral surface heating coil  150  may be directly connected, and the other end of each receiving coil  140  and the other end of each lateral surface heating coil  150  may be connected through both ends of the resonance capacitor (Cr). Accordingly, the receiving coil  140 , the lateral surface heating coil  150  and the resonance capacitor (Cr) may form an L-C resonance circuit (RC). 
     The L-C resonance circuit (RC) may be magnetically coupled to the working coil  210  around a resonance frequency. In this case, entire impedance of the wireless induction heating cooker  100  may become very high. Accordingly, a magnetic field generated in the working coil  210  may have high intensity, and a large amount of heat may be generated in the internal pot  130 . 
     As each of the plurality of receiving coils  140  and each of the plurality of lateral surface heating coils  150  are connected to each other as described above, induced currents may be supplied to the plurality of lateral surface heating coils  150  by the plurality of receiving coils  140  connected to the plurality of lateral surface heating coils  150 . That is, as described above, the electric currents induced to the receiving coil  140  may be supplied to the lateral surface heating coil  150  connected to the receiving coil  140 . 
     In this case, the lateral surface heating coil  150  may heat the lateral surface of the internal pot  130  using the induced currents supplied by the receiving coil  140 . Specifically, when induced currents flow through the lateral surface heating coil  150 , a magnetic field may be generated in the lateral surface heating coil  150 . The magnetic field generated in the lateral surface heating coil  150  may induce electric currents to the lateral surface of the internal pot  130 , and Joule&#39;s heat may be generated on the lateral surface of the internal pot  130  by the induced currents. 
     That is, the internal pot  130 , as described above, may be heated by a magnetic field generated in the working coil  210  or by a magnetic field generated in the receiving coil  140  or by a magnetic field generated in the lateral surface heating coil  150 . 
     The present disclosure, as described above, may heat even the lateral surface of the internal pot  130  using a magnetic field generated in the working coil  210  of the induction heating apparatus, thereby forming a plurality of paths for heat delivery with a single heat source and ensuring temperature uniformity based on height of the internal pot  130 . 
     Below, an arrangement of the receiving coil  140  and the lateral surface heating coil  150  on opposite sides is described. For convenience of description, two pairs of the receiving coils  140  and the lateral surface heating coils  150  are described. 
     Referring to  FIG. 5  that is a longitudinal cross-sectional view of the internal pot  130 , the receiving coil  140  and the lateral surface heating coil  150 , the plurality of receiving coils  140  may include first and second receiving coils  140   a ,  140   b . In this case, the lateral surface heating coil  150  may include a first lateral surface heating coil  150   a  connected to the first receiving coil  140   a  and disposed on the opposite side of the first receiving coil  140   a , and a second lateral surface heating coil  150   b  connected to the second receiving coil  140   b  and disposed on the opposite side of the second receiving coil  140   b.    
     The connected receiving coil  140  and lateral surface heating coil  150  may form a pair. Specifically, the first receiving coil  140   a , and the first lateral surface heating coil  150   a  connected with the first receiving coil  140   a  may form a pair, and the second receiving coil  140   b , and the second lateral surface heating coil  150   b  connected with the second receiving coil  140   b  may form a pair. 
     The receiving coil  140 , as described above, may be disposed on the bottom surface  110   b  of the main body  110 , and the lateral surface heating coil  150  may be disposed on the lateral surface of the internal pot  130 . In this case, a pair of the receiving coil  140  and the lateral surface heating coil  150  may be disposed on opposite sides. 
     Specifically, as illustrated in  FIG. 5 , in case the first receiving coil  140   a  is placed on the left side of the bottom surface  110   b  of the main body  110 , the first lateral surface heating coil  150   a  may be placed on the right side of the lateral surface of the internal pot  130 . Likewise, in case the second receiving coil  140   b  is placed on the right side of the bottom surface  110   b  of the main body  110 , the second lateral surface heating coil  150   b  may be placed on the left side of the lateral surface of the internal pot  130 . 
     In some examples, where the internal pot  130  has a cylinder shape or a polyprism shape, centers of the receiving coil  140  and the lateral surface heating coil  150  may be connected to each other. In other words, centers of the pair of the receiving coil  140  and the lateral surface heating coil  150  may be respectively placed on a straight line that crosses a central perpendicular line (CL) of the internal pot  130 . For example, the plurality of receiving coils  140  may be arranged symmetrically with respect to a reference line that vertically passes a center of the internal pot. In this case, the reference line is the central perpendicular line (CL) of the internal pot  130 . 
     Referring back to  FIG. 5 , an outer circumferential surface of the internal pot  130  may have a predetermined radius with respect to the central perpendicular line (CL). In this case, a center (CP 1 ) of the first receiving coil  140   a  and a center (CP 1 ′) of the first lateral surface heating coil  150   a  may be placed on a straight line that passes the central perpendicular line (CL). Additional, a center (CP 2 ) of the second receiving coil  140   b  and a center (CP 2 ′) of the second lateral surface heating coil  150   b  may be placed on the straight line that passes the central perpendicular line (CL). 
     In some examples, each of the plurality of lateral surface heating coils  150  may be disposed on a plane that is inclined with respect to the bottom surface of the main body. For example, each of the plurality of lateral surface heating coils  150  may ha a lower edge and an upper end disposed vertically above the lower edge, where a radial distance between the central perpendicular line (CL) and the lower end may be less than a radial distance between the central perpendicular line (CL) and the upper end. 
     Referring to  FIG. 6A  separately illustrating only the plurality of receiving coils  140  and the plurality of lateral surface heating coils  150 , and  FIG. 6B  separately illustrating a state in which the internal pot  130  and the metallic plate  130   a  are stored on the coil in  FIG. 6A , a wireless induction heating apparatus may include six pairs of the receiving coils  140   a ,  140   b ,  140   c ,  140   d ,  140   e ,  140   f  and the lateral surface heating coils  150   a ,  150   b ,  150   c ,  150   d ,  150   e ,  150   f . Each pair of the receiving coil  140  and the lateral surface heating coil  150  may be electrically connected and may be placed on opposite sides. 
     The above-described features of positions may be applied to a polyprism-shaped internal pot  130 . Accordingly, regardless of the shape of the internal pot  130 , a pair of the receiving coil  140  and the lateral surface heating coil  150  may be placed completely on opposite sides. 
     Below, features of an arrangement of the plurality of receiving coils  140  and an arrangement of the plurality of lateral surface heating coils  150  are described. 
     A center of each of the plurality of receiving coils  140  and a center of each of the plurality of lateral surface heating coils  150  may be placed in parallel along a circumferential direction of the internal pot  130 . 
     Referring to  FIG. 6A , and  FIG. 7A  illustrating the plurality of receiving coils  140  seen from the Z-axis direction (see. axes of the coordinate in  FIG. 1 ), in case the internal pot  130  has a cylinder shape, centers (CP 1  to CP 6 ) of the plurality of receiving coils  140  may be placed in parallel along the circumferential direction, i.e., the circumferential direction of the internal pot  130  on the bottom surface  110   b  of the main body  110 . 
     Referring to  FIGS. 6A and 7B , in case the internal pot  130  has a cylinder shape, centers (CP 1 ′ to CP 6 ′) of the plurality of lateral surface heating coils  150  may be placed in parallel along the circumferential direction, i.e., the circumferential direction of the internal pot  130  on the lateral surface of the internal pot  130 . 
     In this case, each of the plurality of lateral surface heating coils  150  may have the same height. Specifically, a height from the bottom surface  110   b  of the main body  110  to the center of each lateral surface heating coil  150  may be the same. Accordingly, the plurality of lateral surface heating coils  150  may heat the lateral surface of the internal pot  130  at the same height. 
     The plurality of receiving coils  140  and the plurality of lateral surface heating coils  150  may be arranged regularly and in a parallel fashion. 
     Specifically, referring to  FIG. 7A , a distance from the central perpendicular line (CL) of the internal pot  130  to the center (CP 1  to CP 6 ) of each receiving coil  140  may be D 1  that is the same. Further, referring to  FIG. 7B , a distance from the central perpendicular line (CL) of the internal pot  130  to the center (CP 1  to CP 6 ) of each lateral surface heating coil  150  may be D 2  that is the same. 
     Referring to  FIGS. 7A and 7B , central angles defined about the central perpendicular line (CL) of the internal pot  130  between any two adjacent receiving coils  140  (specifically, centers of two receiving coils  140 ) among the plurality of receiving coils  140  may be defined as 8. The central angles between receiving coils  140  may be equal to one another. Further, a central angle defined about the central perpendicular line (CL) of the internal pot  130  between two adjacent lateral surface heating coils  150  (specifically, centers of two lateral surface heating coils  150 ) among the plurality of lateral surface heating coils  150  may be defined as 8. The central angles between the lateral surface heating coils  150  may be equal to one another. 
     Below, features of positions of the plurality of receiving coils  140  are described. 
     Referring to  FIGS. 8A and 8B , the internal pot  130  may include a round portion or a round area (RA) to easily take out a cooked object after an object is cooked. For example, the round area (RA) may extends between a first portion defining a first reference radius (R 1 ) of the internal pot  130  and a second portion defining a second reference radius (R 2 ) of the internal pot  130 . In other words, the round area (RA) may be formed from an outer side of the first reference radius (R 1 ) to an inner side of the second reference radius (R 2 ). The second reference radius (R 2 ) may be greater than the first reference radius (R 1 ). 
     The internal pot  130 , as described above, may be heated by a magnetic field generated in the working coil  210 , or by a magnetic field generated in the receiving coil  140 . In case there are a large number of mediums in the delivery of power, heating efficiency may be deteriorated. In some examples, the internal pot  130  may be heated directly by a magnetic field generated in the working coil  210  rather than by a magnetic field generated in the receiving coil  140  to ensure higher heating efficiency. 
     In case the receiving coil  140  is placed outside of the working coil  210 , electric currents may not be induced to the receiving coil  410  and the lateral surface heating coil  150 . The receiving coil  140  may be placed to perpendicularly overlap with the working coil  210 . 
     Referring back to  FIGS. 8A and 8B , the internal pot  130  is far from the working coil  210  in the round area (RA). Accordingly, an amount of heat generated by a magnetic field generated in the working coil  210  may be reduced. 
     In this case, the plurality of receiving coils  140 , as illustrated in  FIG. 8A , may be placed at a lower portion of the round area (RA), i.e., between the first reference radius (R 1 ) and the second reference radius (R 2 ). Further, the plurality of receiving coils  140 , as illustrated in  FIG. 8B , may be placed outside of the first reference radius (R 1 ). When the wireless induction heating cooker  100  is aligned on the working coil  210  in case the plurality of receiving coils  140  are placed outside of the first reference radius (R 1 ), the plurality of receiving coils  140  may be placed at an inner side of the working coil  210  to perpendicularly overlap with the working coil  210 . 
     When the receiving coil  140  is placed at the lower portion of the round area (RA) or at the lower portion of an outside area including the round area (RA) where a relatively small amount of heat is generated, electric currents induced to the working coil  210  may be supplied to the lateral surface heating coil  150  without significantly reducing an entire amount of heat generated in the internal pot  130 , i.e., an amount of heat that heats the internal pot  130  using a magnetic field generated in the working coil  210 . Thus, the present disclosure may efficiently use a magnetic field generated in the working coil  210  to heat the lower portion and the lateral surface of the internal pot  130 . 
     Below, features of positions of the plurality of lateral surface heating coils  150  are described. 
     The plurality of lateral surface heating coils  150  may be arranged perpendicularly on the outer surface of the internal pot  130 . 
     Referring to  FIG. 9A , the internal pot  130 , as described with reference to  FIGS. 8A and 8B , may include the round area (RA). In this case, the plurality of lateral surface heating coils  150  may be perpendicularly arranged on the outer surface of the internal pot  130  at a height higher than that of the round area (RA). The lateral surface heating coil  150  may be formed horizontally concavely on the basis of curvature of the outer circumferential surface of the internal pot  130 . For instance, each of the plurality of lateral surface heating coils  150  may have a convex shape that protrudes outward relative to the lateral surface of the internal pot  130 . 
     The plurality of lateral surface heating coils  150  may also be concavely formed along the round area (RA) of the internal pot  130 . 
     Referring to  FIG. 9B , when the internal pot  130  includes the round area (RA), the plurality of lateral surface heating coils  150  may be arranged on the outer surface of the internal pot  130  across the round area (RA). Accordingly, the plurality of lateral surface heating coils  150  may be formed horizontally concavely on the basis of curvature of an outer circumferential surface of the internal pot  130  or may be formed perpendicularly concavely on the basis of curvature of the round area (RA). 
     Below, a process, in which cooking uniformity is provided through the above-described receiving coil  140  and lateral surface heating coil  150  even when the wireless induction heating cooker  100  is partially misaligned on the working coil  210  of the induction heating apparatus, is described with reference to  FIG. 10 . For convenience of description, two pairs of the receiving coil  140  and the lateral surface heating coil  150  are only illustrated in  FIG. 10 . 
     The wireless induction heating cooker  100  may be misaligned with the working coil  210  by a predetermined distance (d). Specifically, the central perpendicular line (CL) of the internal pot  130  may be misaligned with respect to a central perpendicular line (CL′) of the working coil  210  to the right side by d. 
     In some cases, due to the misalignment, the right side of the internal pot  130  may be placed outside of the working coil  210 . Accordingly, an amount of heat delivered to the right side of the internal pot  130  may be smaller than an amount of heat delivered to the left side of the internal pot  130 . 
     In some cases, due to the misalignment, the first receiving coil  140   a  placed at a lower portion of the left side of the internal pot  130  may be moved to a central portion of the working coil  210  and may perpendicularly overlap with the working coil  210  completely, and the second receiving coil  140   b  placed at a lower portion of the right side of the internal pot  130  may be moved to an outer side of the working coil  210  such that only a part of the second receiving coil  140   b  perpendicularly overlaps with the working coil  210 . 
     Accordingly, an amount of electric currents induced to the first receiving coil  140   b  may be larger than an amount of electric currents induced to the second receiving coil  140   b . The first lateral surface heating coil  150   a  may generate a magnetic field using the electric currents induce to the first receiving coil  140   a , and the second lateral surface heating coil  150   b  may generate a magnetic field using the electric currents induced to the second receiving coil  140   b . Thus, the first lateral surface heating coil  150   a  placed on a right surface of the internal pot  130  may deliver a larger amount of heat to the internal pot  130  than the second lateral surface heating coil  150   b  placed on a left surface of the internal pot  130 . 
     That is, the first lateral surface heating coil  150   a  may additionally deliver a large amount of heat to the right surface of the internal pot  130  to which a relatively small amount of heat is delivered directly from the working coil  210 . Under the same theory, the second lateral surface heating coil  150   b  may additionally deliver a small amount of heat to the left surface of the internal pot  130  to which a relatively large amount of heat is delivered directly from the working coil  210 . 
     By doing so, even when the wireless induction heating cooker  100  is misaligned from the working coil  210  by the predetermined distance (d), temperatures of the left side and right side of the internal pot  130  may be maintained similarly, and cooking uniformity of an object cooked in the internal pot  130  may be provided. 
     The present disclosure, as described above, may provide cooking uniformity even when the wireless induction heating cooker  100  is partially misaligned on the working coil  210  of the induction heating apparatus, thereby ensuring quality cooking uniformity regardless of the position of the wireless induction heating cooker  100  and improving user convenience without strictly requiring a user to align the wireless induction heating cooker  100 . 
     The present disclosure has been described with reference to the implementations illustrated in the drawings. However, the disclosure is not limited to the implementations and the drawings set forth herein. Further, various modifications may be made by one having ordinary skill in the art within the scope of the technical spirit of the disclosure. Further, though not explicitly described during description of the implementations of the disclosure, effects and predictable effects according to the configuration of the disclosure should be included in the scope of the disclosure.