Patent Publication Number: US-11382184-B2

Title: Cooking Apparatus and control method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based on and claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2018-0061141, filed on May 29, 2018, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Field 
     The disclosure relates to a cooking apparatus and a control method thereof, and more particularly to a cooking apparatus having a plurality of induction coils and a control method thereof. 
     2. Description of Related Art 
     In general, an induction heating cooker is a cooking appliance for heating a cooking vessel using the principle of induction heating for cooking. The induction heating cooker may include a cooking table on which a cooking vessel is put, and a coil configured to generate a magnetic field using an electric current. 
     When the current is applied to the coil to generate a magnetic field, a secondary current is induced in the cooking vessel, and joule heat is generated by the electrical resistance component of the cooking vessel itself. The cooking vessel is heated by the joule heat and food contained in the cooking vessel is heated. 
     In comparison with a gas range or a kerosene stove in which fossil fuels such as gas or oil are burned and the cooking vessel is heated through the heat of combustion thereof, the induction heating cooker provides faster heating without harmful gas and the risk of fire. 
     Recently, a new induction heating cooker has been developed and the new induction heating cooker is capable of automatically heating a cooking vessel if the cooking vessel is placed in at any location on the induction heating cooker. The induction heating cooker includes a plurality of coils. 
     SUMMARY 
     Therefore, it is an aspect of the present disclosure to provide a cooking apparatus capable of increasing a magnitude of a magnetic field output by coils overlapped with a cooking vessel, and a control method thereof. 
     It is another aspect of the present disclosure to provide a cooking apparatus capable of supplying power to each coil overlapped with a cooking vessel from a plurality of external power supplies, and a control method thereof. 
     It is another aspect of the present disclosure to provide a cooking apparatus capable of supplying power to each of a plurality of inverters from each of a plurality of rectifiers, and a control method thereof 
     Additional aspects of the present disclosure will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present disclosure. 
     In accordance with an aspect of the disclosure, a cooking apparatus includes first and second coils arranged in a first column, third and fourth coils arranged in a second column, a plurality of inverters configured to supply a drive current to the first, second third and fourth coils, a plurality of rectifiers configured to supply direct current (DC) power to the plurality of inverters, a plurality of switches configured to connect each of the plurality of rectifiers to any one of a first external power supply and a second external power supply, and a controller configured to control the plurality of switches wherein the first external power supply supplies power to at least one of the first, second, third, and fourth coils and the second external power supply supplies power to at least one of the first, second, third, and fourth coils. 
     Based on whether a sum of power of the first coil and power of the second coil is greater than reference power, the controller may control the plurality of switches wherein the first external power supply supplies power to the first coil and the second external power supply supplies power to the second coil. 
     Based on whether the power of the first coil is greater than the power of the second coil, the controller may control the plurality of switches wherein the second external power supply supplies power to the third and fourth coils. 
     The plurality of inverters may include first, second, third and fourth inverters configured to supply a drive current to the first, second, third, and fourth coils, respectively, the plurality of rectifiers may include first, second, third and fourth rectifiers configured to supply DC power to the first, second, third, and fourth inverters, respectively, and the plurality of switches may include first, second, third and fourth three-contact switches configured to connect each of the first, second, third and fourth rectifiers to any one of the first and second external power supplies. 
     Based on whether the sum of the power of the first coil and the power of the second coil is greater than the reference power, the controller may control the first and second three-contact switches wherein the first rectifier is connected to the first external power supply and the second rectifier is connected to the second external power supply. 
     Based on whether the power of the first coil is greater than the power of the second coil, the controller may control the third and fourth three-contact switches wherein the third and fourth rectifiers are connected to the second external power supply. 
     The plurality of inverters may include first, second, third and fourth inverters configured to supply a drive current to the first, second, third, and fourth coils, respectively, the plurality of rectifiers may include first and second rectifiers configured to supply DC power to the first and second inverters, respectively and a third rectifier configured to supply DC power to the third and fourth inverters, and the plurality of switches may include first, second, and third three-contact switches configured to connect each of the first, second and third rectifiers to any one of the first and second external power supplies. 
     Based on whether the sum of the power of the first coil and the power of the second coil is greater than the reference power, the controller may control the first and second three-contact switches wherein the first rectifier is connected to the first external power supply and the second rectifier is connected to the second external power supply. 
     Based on whether the power of the first coil is greater than the power of the second coil, the controller may control the third three-contact switch wherein the third rectifier is connected to the second external power supply. 
     In accordance with another aspect of the disclosure, a control method of the cooking apparatus configured to supply power from first and second external power supplies to first, second, third and fourth coils, the control method includes identifying power of each of the first, second, third and fourth coils based on a user input, and based on whether a sum of power of the first coil and power of the second coil is greater than reference power, supplying power from the first external power supply to the first coil and supplying power from the second external power supply to the second coil. 
     The control method may further include based on whether the power of the first coil is greater than the power of the second coil, supplying power from the second external power supply to the third and fourth coils. 
     Power may be supplied from the first and second external power supplies to the first, second, third and fourth coils by using first, second, third and fourth switches configured to connect each of the first, second, third and fourth coils to any one of the first and second external power supplies. 
     The control method may further include based on whether the sum of the power of the first coil and the power of the second coil is greater than the reference power, controlling the first and second switches wherein the first coil is connected to the first external power supply and the second coil is connected to the second external power supply. 
     The control method may further include based on whether the power of the first coil is greater than the power of the second coil, controlling the first and second switches wherein the third and fourth rectifiers are connected to the second external power supply. 
     The control method may further include when the sum of the power of the first coil and the power of the second coil is not greater than the reference power and when a sum of power of the third coil and power of the fourth coil is not greater than the reference power, supplying power from the first external power supply to the first and second coils and supplying power from the second external power supply to the third and fourth coils. 
     In accordance with another aspect of the disclosure, a cooking apparatus includes a plurality of coils, a plurality of inverters configured to supply a drive current to each of the plurality of coils, a plurality of rectifiers configured to supply direct current (DC) power to each of the plurality of inverters, a plurality of switches configured to connect each of the plurality of rectifiers to any one of a first external power supply and a second external power supply, and a controller configured to control the plurality of switches wherein the first external power supply supplies power to coils in a first group, among the plurality of coils and the second external power supply supplies power to coils in a second group, among the plurality of coils. 
     Based on whether a sum of power of the first group coils is greater than reference power, the controller may control the plurality of switches wherein the first and second external power supplies supply power to the first group coils. 
     Based on whether power of any one coil of the plurality of coils is greater than reference power, the controller may control the plurality of switches wherein the first external power supply supplies power to the any one coil and the second external power supply supplies power to the other coils. 
     The first group coils may be arranged in a first column and the second group coils are arranged in a second column. 
     The number of the plurality of inverters may be identical to the number of the plurality of rectifiers. 
     Before undertaking the DETAILED DESCRIPTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term “controller” means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. 
     Moreover, various functions described below can be implemented or supported by one or more computer programs, each of which is formed from computer readable program code and embodied in a computer readable medium. The terms “application” and “program” refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or a portion thereof adapted for implementation in a suitable computer readable program code. The phrase “computer readable program code” includes any type of computer code, including source code, object code, and executable code. The phrase “computer readable medium” includes any type of medium capable of being accessed by a computer, such as read only memory (ROM), random access memory (RAM), a hard disk drive, a compact disc (CD), a digital video disc (DVD), or any other type of memory. A “non-transitory” computer readable medium excludes wired, wireless, optical, or other communication links that transport transitory electrical or other signals. A non-transitory computer readable medium includes media where data can be permanently stored and media where data can be stored and later overwritten, such as a rewritable optical disc or an erasable memory device. 
     Definitions for certain words and phrases are provided throughout this patent document. Those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects of the disclosure will become apparent and more readily appreciated from the following description of embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  illustrates a view of an exterior of a cooking apparatus according to an embodiment of the disclosure; 
         FIG. 2  illustrates a view of an interior of the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 3  illustrates a view of an example in which the cooking apparatus according to an embodiment of the disclosure heats a cooking vessel; 
         FIG. 4  illustrates a view of a configuration of the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 5  illustrates a view of an example of a driver contained in the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 6  is a view particularly illustrating a first rectifier, a first inverter, and a first coil shown in  FIG. 5 ; 
         FIG. 7  is a view illustrating an example of a current flow of a first inverter and a first coil contained in the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 8  is a view illustrating another example of the current flow of the first inverter and the first coil contained in the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 9  is a view illustrating output of the first coil according to an operating frequency of the first inverter contained in the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 10  illustrates a view of an example of a switching circuit contained in the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 11  illustrates a view of another example of the switching circuit contained in the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 12  illustrates a view of operations of power distribution of the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 13  illustrates a view of other operations of the power distribution of the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 14  is a view illustrating an example of power supply to a plurality of coils according to the operation of the power distribution of  FIGS. 12 and 13 ; 
         FIG. 15  is a view illustrating another example of the power supply to the plurality of coils according to the operation of the power distribution of  FIGS. 12 and 13 ; 
         FIG. 16  illustrates a view of another example of the driver contained in the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 17  illustrates a view of an interior of the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 18  illustrates a view of an example of a driver contained in the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 19  illustrates a view of an example of a switching circuit contained in the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 20  illustrates a view of another example of the driver contained in the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 21  illustrates a view of another example of the driver contained in the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 22  illustrates a view of another example of the driver contained in the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 23  illustrates a view of another example of the driver contained in the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 24  illustrates a view of another example of the driver contained in the cooking apparatus according to an embodiment of the disclosure; 
         FIG. 25  illustrates a view of another example of the driver contained in the cooking apparatus according to an embodiment of the disclosure; and 
         FIG. 26  illustrates a view of another example of operation of the power distribution of the cooking apparatus according to an embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 through 26 , discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged system or device. 
     The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. Accordingly, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be suggested to those of ordinary skill in the art. The progression of processing operations described is an example; however, the sequence of and/or operations is not limited to that set forth herein and may be changed as is known in the art, with the exception of operations necessarily occurring in a particular order. In addition, respective descriptions of well-known functions and constructions may be omitted for increased clarity and conciseness. 
     Additionally, various embodiments will now be described more fully hereinafter with reference to the accompanying drawings. The various embodiments may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete and will fully convey the various embodiments to those of ordinary skill in the art. Like numerals denote like elements throughout. 
     It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. As used herein, the term “and/or,” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that when an element is referred to as being “connected,” or “coupled,” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected,” or “directly coupled,” to another element, there are no intervening elements present. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the,” are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
     Reference will now be made in detail to the various embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
     The expression, “at least one of a, b, and c,” should be understood as including only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c. 
     Reference will now be made in detail to embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. 
       FIG. 1  illustrates a view of an exterior of a cooking apparatus according to an embodiment of the disclosure.  FIG. 2  illustrates a view of an interior of the cooking apparatus according to an embodiment of the disclosure.  FIG. 3  illustrates a view of an example in which the cooking apparatus according to an embodiment of the disclosure heats a cooking vessel. 
     As illustrated in  FIG. 1 , a cooking apparatus  100  includes a body  101  forming an appearance thereof and on which various components forming the cooking apparatus  100  are installed. 
     On an upper surface  101   a  of the body  101 , a cooking plate  102  having a flat plate shape on which a cooking vessel  1  is placed is provided. The cooking plate  102  may be formed of a reinforcing glass such as a ceramic glass so as not to be easily broken. 
     On one side of the cooking plate  102 , a user interface  110  receiving control commands from a user and displaying operation information of the cooking apparatus  100  may be installed. However, the position of the user interface  110  is not limited to a position on the cooking plate  102  but may be installed on at various positions such as the front surface  101   b  and/or a side surface  101   c  of the body  101 . 
     As illustrated in  FIG. 2 , a plurality of coils  120 :  121 ,  122 ,  123 , and  124  configured to heat the cooking vessel  1  and a main circuit board assembly  110   a  configured to implement the user interface  110  may be installed under the cooking plate  102 . 
     The plurality of coils  120  each may generate a magnetic field and/or an electric field and/or an electromagnetic field for heating the cooking vessel  1 . 
     For example, when a drive current is supplied to a coil  120   a  as illustrated in  FIG. 3 , a magnetic field B may be induced around the coil  120   a . Particularly, when a current having magnitudes and directions changing in time, that is, an alternating current, is supplied to the coil  120   a , the magnetic field B having the magnitude and direction changing in time may be induced around the coil  120   a.    
     The magnetic field B around the coil  120   a  may pass through the cooking plate  102  formed of tempered glass and then reach the cooking vessel  1  placed on the cooking plate  102 . 
     An eddy current EI rotating around the magnetic field B may occur in the cooking vessel  1  due to the magnetic field B having the magnitude and direction changing with time. The phenomenon that an eddy current is generated due to the magnetic field B changing in time is referred to as electromagnetic induction phenomenon. Heat caused by electrical resistance may be generated in the cooking vessel  1  due to eddy currents EI. Heat generated by electrical resistance is heat generated in a resistor when a current flows through the resistor, which is also referred to as a joule heat. The cooking vessel  1  is heated by the heat caused by the electrical resistance, and food contained in the cooking vessel  1  may be heated. 
     As described above, the plurality of coils  120  each may heat the cooking vessel  1  using heat due to electromagnetic induction and the electrical resistance. 
     The plurality of coils  120  may be arranged in a predetermined pattern under the cooking plate  102 . The plurality of coils  120  may be arranged as a matrix with columns and rows. In other words, the plurality of coils  120  may be arranged at predetermined intervals from the front to the rear of the body  101 , and may be arranged at predetermined intervals from the right side to the left side of the body  101 . For example, the plurality of coils  120  may include a first coil  121 , a second coil  122 , a third coil  123 , and a fourth coil  124 . The first and second coils  121  and  122  may be arranged in a first column (a left column of the cooking plate) and the third and fourth coils  123  and  124  may be arranged in a second column (a right column of the cooking plate). 
     Arrangement of the plurality of coils  120  is not limited to the arrangement illustrated in  FIG. 2 , and thus the plurality of coils  120  may be arranged in various forms. For example, the plurality of coils  120  may be arranged in the form of a honeycomb to allow a distance among the plurality of coils  120  to be minimized. 
     The main circuit board assembly  110   a  implementing the user interface  110  may be provided under the user interface  110  installed at one side of the cooking plate  102 . The main circuit board assembly  110   a  may be a printed board assembly (PBA) including a display, a switching element and an integrated circuit element, and a printed circuit board (PCB), on which the display, the switching element, and the integrated circuit element are installed, for implementing the user interface  110 . 
     The position of the main circuit board assembly  110   a  is not limited to that illustrated in  FIG. 2 , and may be arranged at various positions. For example, when the user interface  110  is installed on the front surface  101   b  of the body  101 , the main circuit board assembly  110   a  may be installed behind the front surface  101   b  of the body  101 . 
     Under the plurality of coils  120 , a printed circuit board assembly (not shown) configured to operate the plurality of coils  120  may be installed. A driver circuit configured to supply a drive current to the plurality of coils  120  and a control circuit configured to control the operation of the plurality of coils  120  may be installed on a plurality of printed circuit board assemblies. 
     As mentioned above, the cooking apparatus  100  may include the plurality of coils  120  configured to heat the cooking vessel  1 , and the driver circuit and the control circuit configured to operate the plurality of coils  120 . 
     Hereinafter a configuration and a function of the configuration of the cooking apparatus  100  will be described in more detail. 
       FIG. 4  illustrates a view of a configuration of the cooking apparatus according to an embodiment of the disclosure.  FIG. 5  illustrates a view of an example of a driver contained in the cooking apparatus according to an embodiment of the disclosure. 
     As illustrated in  FIG. 4 , the cooking apparatus  100  includes the user interface  110 , the plurality of coils  120 , a driver  130  and a controller  140 . 
     The user interface  110  may include a user input  111  receiving a control command from a user and a display  112  displaying an image related to the operation of the cooking apparatus  100 . 
     The user input  111  may include an input button receiving a predetermined control command and a touch pad receiving various control commands according to an image displayed on the display  112 . 
     The input button may include a plurality of buttons receiving a predetermined control command from the user and transmitting an electrical signal corresponding to the user&#39;s control command to the controller  140 . For example, the input button may include an operation button receiving a power on/off command of the cooking apparatus  100 , and a power-up button and a power-down button receiving a magnitude of the magnetic field and/or the electromagnetic field output by the coils  120  of the cooking apparatus  100 . The input button may be implemented with various types of buttons (or switches) such as a push button, a slide button, a toggle button, a touch button, and a dial. 
     The touch pad may receive a touch input from a user and transmit coordinates of the received touch input to the controller  140 . The controller  140  may identify the user&#39;s control command based on the coordinates of the touch input. 
     The display  112  may display an image related to the operation of the cooking apparatus  100 . For example, the display  112  may display an image indicating whether the coils  120  of the cooking apparatus  100  are in operation, and an image indicating the magnitude of the magnetic field and/or the electromagnetic field output by the coils  120 . 
     The display  112  may include a light emitting diode (LED), a liquid crystal display (LCD), or an organic light emitting diode (OLED). 
     The user input  111  and the display  112  may be integrally formed. For example, the touch pad and the display may form a touch screen panel (TSP) integrally. The display may display an image for receiving a user&#39;s touch input, and the touch pad may receive a user&#39;s touch input. The controller  140  may identify the user&#39;s control command based on the coordinates of the touch input of the user. 
     As mentioned above, the user interface  110  may receive the control command from the user, and transmit the electrical signal corresponding to the user&#39;s control command to the controller  140 . The user interface  110  may receive information on the operation of the cooking apparatus  100  from the controller  140  and display an image indicating the operation of the cooking apparatus  100 . 
     For example, the user interface  110  may display an image indicating a position of the cooking vessel  1  placed on the cooking plate  102 , on the display  112 . In addition, the user interface  110  may receive the touch input of the user indicating a selection of the cooking vessel  1  through the user input  111 , and transmit the touch input of the user to the controller  140 . When the user inputs an output increase command of the cooking apparatus  100  through the user input  111 , the user interface  110  may transmit an electrical signal indicating the output increase command to the controller  140 , and when the user inputs an output decrease command of the cooking apparatus  100  through the user input  111 , the user interface  110  may transmit an electrical signal indicating the output decrease command to the controller  140 . 
     When the cooking vessel  1  is placed on the cooking plate  102 , the plurality of coils  120  each may generate the magnetic field and/or the electromagnetic field for heating the cooking vessel  1 . 
     As mentioned above, the plurality of coils  120  may include the first coil  121 , the second coil  122 , the third coil  123  and the fourth coil  124 . The first and second coils  121  and  122  may be arranged in the left column of the cooking plate  102  and the third and fourth coils  123  and  124  may be arranged in the right column of the cooking plate  102 . 
     The driver  130  may be supplied with power from an external power supply PS and may supply the drive current to the plurality of coils  120  according to the driving control signal of the controller  140 . Particularly, a driver circuit  133  may apply an alternating current (AC) and output an alternating current (drive current) voltage to the plurality of coils  120  in accordance with the control signal of the controller  140 . 
     The driver  130  includes the driver circuit  133 , a rectifier circuit  132 , and a switching circuit  131 . 
     The driver circuit  133  may include a plurality of inverters  230 . Each of the plurality of inverters  230 :  231 ,  232 ,  233 , and  234  may receive a direct current (DC) voltage and a direct current (DC) from the rectifier circuit  132 , and apply an AC voltage and supply an AC to each of the plurality of coils  120 . 
     The plurality of inverters  230  may include a first inverter  231  supplying a drive current to the first coil  121 , a second inverter  232  supplying a drive current to the second coil  122 , a third inverter  233  supplying a drive current to the third coil  123  and a fourth inverter  234  supplying a drive current to the fourth coil  124 . 
     Although the first, second, third and fourth inverters  231 ,  232 ,  233  and  234  are illustrated in  FIG. 5 , the number of the inverters  230  is not limited to four. The number of the plurality of inverters  230  contained in the driver circuit  133  may be equal to the number of the plurality of coils  120  or may be smaller than the number of the plurality of coils  120 . 
     The rectifier circuit  132  may include a plurality of rectifiers  220 . Each of the plurality of rectifiers  220 :  221 ,  222 ,  223 , and  224  may be supplied with an AC voltage and an AC from the external power supply PS via the switching circuit  131 , and the plurality of rectifiers  220 :  221 ,  222 ,  223 , and  224  may apply a DC voltage and supply a DC to the plurality of inverters  231 ,  232 ,  233 , and  234 , respectively. 
     The plurality of rectifiers  220  may include a first rectifier  221  supplying direct current (DC) power to the first inverter  231 , a second rectifier  222  supplying the DC power to the second inverter  232 , a third rectifier  223  supplying the DC power to the third inverter  233 , and a fourth rectifier  224  supplying the DC power to the fourth inverter  234 . 
     Although the first, second, third, and fourth rectifiers  221 ,  222 ,  223 , and  224  are illustrated in  FIG. 5 , the number of the rectifiers  220  is not limited to four. The number of the plurality of rectifiers  220  contained in the rectifier circuit  132  may be equal to the number of the plurality of inverters  230  or may be smaller than the number of the plurality of inverters  230 . 
     The external power supply PS may include external power supplies capable of supplying alternating current (AC) power having different phases to the cooking apparatus  100 . 
     The power supplied to home and/or the workplace may be single-phase alternating current (AC) power or three-phase alternating current (AC) power. In a power plant, three-phase AC power is generated and the voltage of the three-phase AC power may drop in the substation. At this time, the power may be supplied to the home and/or workplace as three-phase AC power, or may be supplied to the home and/or workplace after converted into the single-phase AC power. 
     Hereinafter for the understanding, it is assumed that three-phase AC power is supplied to the home and/or the workplace. 
     The external power supply PS supplied to the home and/or the workplace may include a first phase terminal L 1 , a second phase terminal L 2 , a third phase terminal L 3  and a neutral terminal N. In other words, the first phase terminal L 1 , the second phase terminal L 2 , the third phase terminal L 3  and the neutral terminal N may be provided from the outside to the home and/or the workplace. 
     First AC power is supplied from the first phase terminal L 1  and the neutral terminal N, and between the first phase terminal L 1  and the neutral terminal N may be defined as a first external power supply PS 1 . Second AC power is supplied from the second phase terminal L 2  and the neutral terminal N, and between the second phase terminal L 2  and the neutral terminal N may be defined as a second external power supply PS 2 . Third AC power is supplied from the third phase terminal L 3  and the neutral terminal N, and between the third phase terminal L 3  and the neutral terminal N may be defined as a third external power supply PS 3 . 
     The first AC power, the second AC power, and the third AC power have a phase difference of 120 degrees with respect to each other. The first external power supply PS 1 , the second external power supply PS 2 , and the third external power supply PS 3  may supply the AC power independently of each other. 
     The cooking apparatus  100  may be supplied with the AC power from the first external power supply PS 1  and the second external power supply PS 2  among the first external power supply PS 1 , the second external power supply PS 2  and the third external power supply PS 3 . In other words, the cooking apparatus  100  may be supplied with different AC power having different phases from the first external power supply PS 1  and the second external power supply PS 2 . 
     The switching circuit  131  may selectively connect the external power supply PS to the rectifier circuit  132 . Particularly, the switching circuit  131  may selectively connect the first and second external power supplies PS 1  and PS 2  to the first, second, third and fourth rectifiers  221 ,  222 ,  223  and  224 . 
     For example, the switching circuit  131  may connect the first external power supply PS 1  to the first and second rectifiers  221  and  222 . The first external power supply PS 1  may supply the AC power to the first and second rectifiers  221  and  222 . The first and second rectifiers  221  and  222  may supply the DC power to the first and second inverters  231  and  232 , respectively. The first and second inverters  231  and  232  may supply the drive current to the first and second coils  121  and  122 . Accordingly, the first external power supply PS 1  may supply the power to the first and second coils  121  and  122  arranged in the left column of the cooking plate  102 . 
     Further, the switching circuit  131  may connect the second external power supply PS 2  to the third and fourth rectifiers  223  and  224 . Accordingly, the second external power supply PS 2  may supply power to the third and fourth coils  123  and  124  arranged in the right column of the cooking plate  102 . 
     Accordingly, the switching circuit  131  may connect the external power supply PS to the rectifier circuit  132  so that the first external power supply PS 1  supplies the power to the first and second coils  121  and  122  and the second external power supply PS 2  supplies the power to the third and fourth coils  123  and  124 . Accordingly, the cooking apparatus  100  may stably supply the power to the first, second, third, and fourth coils  121 ,  122 ,  123 , and  124  from the first and second external power supplies PS 1  and PS 2 . 
     The switching circuit  131  may switch the connection between the external power supply PS and the rectifier circuit  132  according to the output of the coils  121 ,  122 ,  123 , and  124 . For example, when the first coil  121  and the second coil  122  simultaneously operate and when the output of the first coil  121  is greater than a reference output, the switching circuit  131  may connect the external power supply PS to the rectifier circuit  132  so that the first external power supply PS 1  supplies the power to the first coil  121  and the second external power supply PS 2  supplies the power to the second coil  122 . In other words, the switching circuit  131  may connect the first external power supply PS 1  to the first rectifier  221  and may connect the second external power supply PS 2  to the second rectifier  222 . 
     Therefore, although a load is concentrated on one of the plurality of coils  120 , the cooking apparatus  100  may intensively supply the power from the external power supply PS to the coil where a load is concentrated, and thus the cooking apparatus  100  may increase the maximum output of the load-concentrated coil. 
     The controller  140  may control the operation of the driver  130  according to the user input received through the user interface  110 . Particularly, the controller  140  may select at least one coil among the plurality of coils  120  based on user input, and may control the driver  130  so that the driver  130  supplies a drive current to the selected coil. 
     For example, the controller  140  may control the driver  130  so that the driver  130  supplies the drive current to the first coil  121  selected based on the user input, or may control the driver  130  so that the driver  130  supplies the drive current to the first and second coils  121  and  122  selected based on the user input. 
     The controller  140  may identify a coil overlapped with the cooking vessel  1  placed on the cooking plate  102  among the plurality of coils  120 , and may control the driver  130  so that the driver  130  selectively supplies the drive current to the at least one coil overlapped with the cooking vessel  1 . 
     For example, the controller  140  may control the driver  130  so that the driver  130  supplies the drive current to the first coil  121  identified as overlapped with the cooking vessel  1 , or may control the driver  130  so that the driver  130  supplies the drive current to the first and second coils  121  and  122  identified as overlapped with the cooking vessel  1 . 
     Further, the controller  140  may identify the coil overlapped with the cooking vessel  1  based on a change in the inductance of the coils. The inductance of the coil overlapped with the cooking vessel  1  is different from the inductance of the coil not overlapped with the cooking vessel  1  and thus a current flowing in the coil overlapped with the cooking vessel  1  is different from a current flowing in the coil not overlapped with the cooking vessel  1 . 
     The controller  140  may control the driver  130  so that the driver  130  applies a detection voltage to the plurality of coils  120  to detect the cooking vessel  1  at a predetermined time interval. In addition, the controller  140  may detect a current flowing in the plurality of coils through a detection signal. 
     The controller  140  may measure current values flowing in the plurality of coils  120  and may compare the measured current values with a reference current value. At this time, the reference current value may be a current flowing in the coil not overlapped with the cooking vessel  1 . 
     The controller  140  may identify that the coil having the current different from the reference current value is overlapped with the cooking vessel  1 . 
     However, the disclosure is not limited thereto, and the cooking apparatus  100  may identify a coil overlapped with the cooking vessel  1  by measuring frequency, and phase of the AC flowing in the plurality of coils  120 . Further, the cooking apparatus  100  may include a sensor configured to directly detect the cooking vessel  1 . 
     The controller  140  may control the magnitude of the magnetic field and/or the electromagnetic field generated by each of the plurality of coils  120  based on the user input inputted through the user interface  110 . Particularly, based on the user input, the controller  140  may control the drive current (or power) supplied to each of the plurality of coils  120 . 
     The controller  140  may include a processor  141  and a memory  142 . 
     The memory  142  may store control programs and control data for controlling the operation of the cooking apparatus  100 . Particularly, the memory  142  may store a driving program and driving data for controlling the operation of the driver  130 . The memory  142  may also store user input received from the user interface  110  and control instructions generated by the processor  141 . 
     According to the request of the processor  141 , the memory  142  may store programs and/or data, and may provide the stored programs and/or data to the processor  141 . For example, the memory  142  may provide a user input to the processor  141  at the request of the processor  141 . 
     The memory  142  may include a volatile memory such as a Static Random Access Memory (S-RAM) or a Dynamic Random Access Memory (DRAM) that can temporarily store data. In addition, the memory  142  may include a non-volatile memory such as a Read Only Memory (ROM), an Erasable Programmable Read Only Memory (EPROM), an Electrically Erasable Programmable Read Only Memory (EEPROM), or a flash memory that can store data for a long time. 
     The processor  141  may process data of the memory  142  according to a program provided from the memory  142  and may generate a control signal for controlling the driver  130  and the user interface  110  according to the processing result. 
     For example, according to a user input received from the user interface  110 , the processor  141  may generate an output control signal for controlling the drive current (or power) supplied to the plurality of coils  120 . 
     The processor  141  may include a logic operation circuit, an arithmetic operation circuit, and a memory circuit. 
     The memory  142  and the processor  141  may be implemented as a separate integrated circuit (IC), or the memory  142  and the processor  141  may be integrated into one integrated circuit. 
     As mentioned above, by using the plurality of inverters  230 , the cooking apparatus  100  may control the plurality of coils  120  independently of each other. Since the plurality of inverters  230  and the plurality of rectifiers  220  correspond to each other on a one-to-one basis, the cooking apparatus  100  may supply power to the plurality of coils  120  independently of each other. By using the switching circuit  131  configured to connect the plurality of rectifiers  220  each to the first power supply PS 1  or the second power supply PS 2 , the cooking apparatus  100  may increase the maximum power supplied to the plurality of coils  120 . 
     Hereinafter, a configuration and an operation of the plurality of inverters  230 , the plurality of rectifiers  220 , and the switching circuit  131  will be described in detail. 
       FIG. 6  is a view particularly illustrating a first rectifier, a first inverter, and a first coil shown in  FIG. 5 .  FIG. 7  is a view illustrating an example of a current flow of a first inverter and a first coil contained in the cooking apparatus according to an embodiment of the disclosure.  FIG. 8  is a view illustrating another example of the current flow of the first inverter and the first coil contained in the cooking apparatus according to an embodiment of the disclosure.  FIG. 9  is a view illustrating an output of the first coil according to an operating frequency of the first inverter contained in the cooking apparatus according to an embodiment of the disclosure. 
     Hereinafter a configuration and an operation of the first rectifier  221  among the plurality of rectifiers  220 , the first inverter  231  of the plurality of inverters  230 , and the first coil  121  of the plurality of coils  120  will be described. 
     A configuration and an operation of the second, third and fourth rectifiers  222 ,  223  and  224  may be the same as those of the first rectifier  221 , and a configuration and an operation of the second, third and fourth inverters  232 ,  233  and  234  may be the same as those of the first inverter  231 . 
     As illustrated in  FIG. 6 , the first rectifier  221  may include a bridge diode which is installed between a first positive terminal P 1  and a first negative terminal N 1  and configured to convert an AC power to DC power. The bridge diode may convert an AC voltage having magnitude and polarity (positive voltage or negative voltage) changing in time, into a DC voltage having constant magnitude and polarity, and may convert an AC having magnitude and direction (positive current or negative current) changing in time, into a DC having constant magnitude. 
     For example, the bridge diode may include four diodes D 1 , D 2 , D 3 , and D 4 . The four diodes D 1 , D 2 , D 3  and D 4  may form a pair of diodes D 1  and D 2 , and D 3  and D 4  connected in series between the first positive terminal P 1  and the first negative terminal N 1 . The two diode pairs D 1  and D 2 , and D 3  and D 4  may be connected in parallel with each other. The bridge diode may convert an AC voltage having a polarity changing in time, into a positive voltage having a constant polarity and convert an AC having a direction changing in time, into a positive current having a constant direction. 
     In addition, the first rectifier  221  may include a DC link capacitor (clink). Opposite ends of the DC link capacitor (clink) may be connected to the first positive terminal P 1  and the first negative terminal N 1 , respectively, and the DC link capacitor (clink) may convert a positive voltage having a magnitude changing in time, into a DC voltage having a constant magnitude. 
     The first inverter  231  may include a first inverter switch Q 1  and a second inverter switch Q 2 , and a first resonant capacitor C 1  and a second resonant capacitor C 2 . The first inverter switch Q 1  and the second inverter switch Q 2  allow or block the supply of drive current to the first coil  121 . The first resonant capacitor C 1  and the second resonant capacitor C 2  resonate with the first coil  121 . 
     One end of the first inverter switch Q 1  may be connected to the first positive terminal P 1  and one end of the second inverter switch Q 2  is connected to the first negative terminal N 1 . The other end of the first inverter switch Q 1  may be connected to the other end of the second inverter switch Q 2 . In other words, the first inverter switch Q 1  and the second inverter switch Q 2  may be connected in series between the first positive terminal P 1  and the first negative terminal N 1 . 
     The first inverter switch Q 1  and the second inverter switch Q 2  may include a three terminal semiconductor switch configured to be turned on/off at a high speed of 20 kilohertz (kHz) to 70 kHz and configured to have a high response speed. For example, the first inverter switch Q 1  and the second inverter switch Q 2  may include a bipolar junction transistor (BJT), a metal-oxide-semiconductor field effect transistor (MOSFET), an insulated gate bipolar transistor (IGBT), or a thyristor. 
     One end of the first resonant capacitor C 1  may be connected to the first positive terminal P 1  and one end of the second resonant capacitor C 2  may be connected to the first negative terminal N 1 . The other end of the first resonant capacitor C 1  may be connected to the other end of the second resonant capacitor C 2 . In other words, the first resonant capacitor C 1  and the second resonant capacitor C 2  may be connected in series between the first positive terminal P 1  and the first negative terminal N 1 . 
     The first inverter switch Q 1  and the second inverter switch Q 2  may be turned on/off by a control signal of the controller  140 . Further, depending on the turn-on/off of the first inverter switch Q 1  and the second inverter switch Q 2 , a current may flow from the first resonant capacitor C 1  and/or the second resonant capacitor C 2  to the first coil  121  or a current may flow from the first coil  121  to the first resonant capacitor C 1  and/or the second resonant capacitor C 2 . 
     As mentioned above, the magnitude and direction of the current flowing through the first coil  121  may change depending on the turn-on/off of the first inverter switch Q 1  and the second inverter switch Q 2  contained in the first inverter  231 . In other words, an AC may be supplied from the first inverter  231  to the first coil  121 . 
     For example, when the first inverter switch Q 1  is closed (turned on) and the second inverter switch Q 2  is opened (turned off) as illustrated in  FIG. 7 , the current may flow from the first rectifier  221  to the first coil  121  through the first inverter Q 1 . In addition, the current flows to the second resonant capacitor C 2  through the first coil  121 , the electric energy is stored in the second resonant capacitor C 2 , and the voltage of the second resonant capacitor C 2  is increased. At this time, a positive current (a current flowing from the left side to the right side of the induction heating coil in  FIG. 7 ) may flow in the first coil  121 . In addition, due to the increase in the voltage of the second resonant capacitor C 2 , the current may flow from the first resonant capacitor C 1  to the first coil  121 . 
     Further, when the first inverter switch Q 1  is opened (turned off) and the second inverter switch Q 2  is closed (turned on) as illustrated in  FIG. 8 , the current may flow from the second resonant capacitor C 4  to the first coil  121 . A current flowing in the first coil  121  may flow to the first rectifier  221  through the first coil  121 . At this time, a negative current (a current flowing from the right side to the left side of the induction heating coil in  FIG. 8 ) may flow in the first coil  121 . Because the current is output from the second resonant capacitor C 2 , the voltage of the second resonant capacitor C 2  may be reduced and the current may flow from the rectifier circuit  132  to the first coil  121  through the first resonant capacitor C 1 . 
     Accordingly, the resonance may be generated between the first coil  121  and the first and second resonant capacitors C 1  and C 2  according to opening and closing of the first and second inverter switches Q 1  and Q 2 . Due to the resonance between the first coil  121  and the first and second resonant capacitors C 1  and C 2 , the AC may flow in the first coil  121 . 
     The drive current (power) supplied to the first coil  121  may vary according to the turn-on/off frequency (switching frequency) of the first and second inverter switches Q 1  and Q 2 . Therefore, a magnitude of the magnetic field B generated by the first coil  121  may vary according to the switching frequency of the first and second inverter switches Q 1  and Q 2 . 
     For example, the power supplied to the first coil  121  may be maximized when the switching frequency of the first and second inverter switches Q 1  and Q 2  is identical to a resonance frequency f 0  between the first coil  121  and the first and second resonant capacitors C 1  and C 2 . 
     When the switching frequency of the first and second inverter switches Q 1  and Q 2  is greater than the resonance frequency f 0 , the power supplied to the first coil  121  may decrease as the switching frequency increases. As illustrated in  FIG. 9 , power, which is supplied to the first coil  121  when the first and second inverter switches Q 1  and Q 2  are switched with a first frequency f 1  greater than the resonance frequency f 0 , may be greater than power, which is supplied to the first coil  121  when the first and second inverter switches Q 1  and Q 2  are switched with a second frequency f 2  greater than the first frequency f 1 . 
     In addition, when the switching frequency of the first and second inverter switches Q 1  and Q 2  is greater than the resonance frequency f 0 , the magnitude of the magnetic field B generated by the first coil  121  may decrease as the switching frequency increases. 
     When the switching frequency of the first and second inverter switches Q 1  and Q 2  is less than the resonance frequency f 0 , the power supplied to the first coil  121  may decrease as the switching frequency decreases. In addition, when the switching frequency of the first and second inverter switches Q 1  and Q 2  is less than the resonance frequency f 0 , the magnitude of the magnetic field B generated by the first coil  121  may decrease as the switching frequency decreases. 
     As mentioned above, by the switching of the first and second inverter switches Q 1  and Q 2  contained in the first inverter  231 , the AC power may be supplied to the first coil  121 , and the first coil  121  may generate the magnetic field B. The magnitude of the magnetic field B generated by the first coil  121  may vary according to the switching frequency of the first and second inverter switches Q 1  and Q 2 . When the switching frequency of the first and second inverter switches Q 1  and Q 2  is greater than the resonance frequency, the magnitude of the magnetic field B generated by the first coil  121  may decrease as the switching frequency increases. 
       FIG. 10  illustrates a view of an example of a switching circuit contained in the cooking apparatus according to an embodiment of the disclosure. 
     The external power supply PS may include the first external power supply PS 1  and the second external power supply PS 2  for supplying AC power having different phases to the cooking apparatus  100 . 
     The switching circuit  131  may selectively connect the external power supply PS to the rectifier circuit  132 . Particularly, the switching circuit  131  may selectively connect the first, second, third, and fourth rectifiers  221 ,  222 ,  223 , and  224  to the first external power supply PS 1  or the second external power supply PS 2 . For example, the switching circuit  131  may connect the first and second rectifiers  221  and  222  to the first external power supply PS 1  and may connect the third and fourth rectifiers  223  and  224  to the second external power supply PS 2 . 
     The switching circuit  131  may be connected to the first and second external power supplies PS 1  and PS 2 . More particularly, the switching circuit  131  may be connected to the first external power supply PS 1  through the first phase terminal L 1  and the neutral terminal N of the external power supply PS. The switching circuit  131  may be connected to the second external power supply PS 2  through the second phase terminal L 2  and the neutral terminal N of the external power supply PS. The first external power supply PS 1  and the second external power supply PS 2  may supply the AC power having different phases to the cooking apparatus  100 . 
     Further, the switching circuit  131  may be connected to the first, second, third and fourth rectifiers  221 ,  222 ,  223 , and  224 . Particularly, the switching circuit  131  may be connected to the first rectifier  221  through the first positive terminal P 1  and the first negative terminal N 1 . The switching circuit  131  may be connected to the second rectifier  222  through the second positive terminal P 2  and the second negative terminal N 2 . The switching circuit  131  may be connected to the third rectifier  223  through the third positive terminal P 3  and the third negative terminal N 3 . The switching circuit  131  may be connected to the fourth rectifier  224  through the fourth positive terminal P 4  and the fourth negative terminal N 4 . 
     The first, second, third and fourth negative terminals N 1 , N 2 , N 3  and N 4  may be connected to the neutral terminal N of the external power supply PS. 
     The switching circuit  131  may include a plurality of switch modules  210 :  211 ,  212 ,  213 , and  214  configured to selectively connect each of the first, second, third and fourth positive terminals P 1 , P 2 , P 3  and P 4  to the first phase terminal L 1  or the second phase terminal L 2 . 
     The plurality of switch modules  210  may include a first switch module  211  connected to the first positive terminal P 1 , a second switch module  212  connected to the second positive terminal P 2 , a third switch module  213  connected to the third positive terminal P 3 , and a fourth switch module  214  connected to the fourth positive terminal P 4 . 
     The first, second, third and fourth switch modules  211 ,  212 ,  213  and  214  may connect each of the first, second, third and fourth positive terminals P 1 , P 2 , P 3  and P 4  to the first phase terminal L 1  or the second phase terminal L 2  according to a control signal of the controller  140 . The first switch module  211  may connect the first positive terminal P 1  to the first phase terminal L 1  or the second phase terminal L 2 . The second switch module  212  may connect the second positive terminal P 2  to the first phase terminal L 1  or the second phase terminal L 2 . The third switch module  213  may connect the third positive terminal P 3  to the first phase terminal L 1  or the second phase terminal L 2 . The fourth switch module  214  may connect the fourth positive terminal P 4  to the first phase terminal L 1  or the second phase terminal L 2 . 
     For example, the controller  140  may control the first and second switch modules  211  and  212  so that the first and second positive terminals P 1  and P 2  are connected to the first phase terminal L 1 , respectively. The controller  140  may control the third and fourth switch modules  213  and  214  so that the third and fourth positive terminals P 3  and P 4  are connected to the second phase terminal L 2 , respectively. 
     Accordingly, the power may be evenly supplied to the first, second, third, and fourth coils  121 ,  122 ,  123 , and  124  from the first and second external power supplies PS 1  and PS 2 . 
     Further, the first and second coils  121  and  122  arranged in the left column may operate as two or one burner depending on a user input. For example, when a separate cooking vessel  1  is placed in the first and second coils  121  and  122  or when a user inputs an independent command for the first and second coils  121  and  122 , the first and second coils  121  and  122  may operate as two burners. Alternatively, when a single vessel  1  is placed across the first and second coils  121  and  122  or when a user inputs a command for integrally operating the first and second coils  121  and  122 , the first and second coils  121  and  122  may operate as a single burner. The third and fourth coils  123  and  124  arranged in the right column may also operate as two or one burner depending on a user input. 
     According to the output of the coils  121 ,  122 ,  123  and  124 , the controller  140  may switch a connection between the first, second, third and fourth positive terminals P 1 , P 2 , P 3  and P 4  and the first and second phase terminal L 1  and L 2 . For example, when the first coil  121  and the second coil  122  operate simultaneously and a sum of the output of the first coil  121  and the output of the second coil  122  is greater than the reference output, the controller  140  may control the first switch module  211  so that the first positive terminal P 1  is connected to the first phase terminal L 1 , and the controller  140  may control the second switch module  212  so that the second positive terminal P 2  is connected to the second phase terminal L 2 . The controller  140  may control the third and fourth switch modules  213  and  214  in the same manner. 
     Accordingly, it is possible to increase the maximum output of the coil in which the load is concentrated, among the plurality of coils  120 . For example, when the load is concentrated on the first and second coils  121  and  122 , the controller  140  may supply the power from each of the first and second power supplies PS 1  and PS 2  to a corresponding one of the first and second coils  121  and  122 , respectively. 
     The first, second, third and fourth switch modules  211 ,  212 ,  213  and  214  may each include a three-contact relay. 
       FIG. 11  illustrates a view of another example of the switching circuit contained in the cooking apparatus according to an embodiment of the disclosure. 
     As illustrated in  FIG. 11 , the plurality of switch modules  211 ,  212 ,  213  and  214  may include positive switches  211   a ,  212   a ,  213   a , and  214   a , and negative switches  211   b ,  212   b ,  213   b , and  214   b , respectively. The positive switches  211   a ,  212   a ,  213   a  and  214   a  may be connected to the first phase terminal L 1  and the negative switches  211   b ,  212   b ,  213   b  and  214   b  may be connected to the second phase terminal L 2 . 
     The positive switches  211   a ,  212   a ,  213   a , and  214   a  and the negative switches  211   b ,  212   b ,  213   b , and  214   b  may operate in opposite states. For example, while the positive switches  211   a ,  212   a ,  213   a  and  214   a  are turned on, the negative switches  211   b ,  212   b ,  213   b  and  214   b  may be turned off. Further, while the positive switches  211   a ,  212   a ,  213   a  and  214   a  are turned off, the negative switches  211   b ,  212   b ,  213   b  and  214   b  may be turned on. 
     The positive switches  211   a ,  212   a ,  213   a  and  214   a  and the negative switches  211   b ,  212   b ,  213   b  and  214   b  may employ a bipolar junction transistor (BJT), a metal-oxide-semiconductor field effect transistor (MOSFET), an insulated gate bipolar transistor (IGBT), or a thyristor. 
       FIG. 12  illustrates a view of operations of power distribution of the cooking apparatus according to an embodiment of the disclosure.  FIG. 13  illustrates a view of other operations of the power distribution of the cooking apparatus according to an embodiment of the disclosure.  FIG. 14  is a view illustrating an example of power supply to a plurality of coils according to the operation of the power distribution of  FIGS. 12 and 13 .  FIG. 15  is a view illustrating another example of the power supply to the plurality of coils according to the operation of the power distribution of  FIGS. 12 and 13 . 
     Power distribution ( 1000 ) of the cooking apparatus  100  will be described with reference to  FIGS. 12 to 15 . 
     The cooking apparatus  100  receives a user input from a user ( 1010 ). 
     The cooking apparatus  100  may receive information (or a command) on an output level from the user. 
     The user input  111  may include a button indicating output levels (for example, “level  1 ”, and “level  2 ”) that the user can input, and may include a button for increasing an output level (an output up button) or a button for decreasing an output level (an output down button). 
     The user may input the output level to the cooking apparatus  100  through the user interface  110 . For example, the output level may indicate the magnitude of the magnetic field (or the output power of the cooking apparatus) output by the plurality of coils  120  of the cooking apparatus  100 . 
     The output level input by the user may not be an absolute value of the output power of the cooking apparatus  100 , and the output level may be a relative value representative of the output power of the cooking apparatus  100 . For example, as for the output power of the cooking apparatus  100 , “level  2 ” may be defined as greater than “level  1 ”. 
     The user interface  110  may output an electrical signal corresponding to an output level input by a user, to the controller  140 . 
     Based on the output level input by the user, the controller  140  of the cooking apparatus  100  may identify the magnitude of the magnetic field output by the plurality of coils  120  (or the output power of the cooking apparatus). The memory  142  of the controller  140  may store a lookup table including the output level of the user and the output power of the cooking apparatus  100  corresponding to the output level. 
     By using the lookup table, the controller  140  may identify the output power of the cooking apparatus  100  based on the output level input by the user. For example, the controller  140  may control the driver  130  so that the plurality of coils  120  outputs the magnetic field corresponding to the power of 100 watt (W) in response to the input of “level  1 ”, and the controller  140  may control the driver  130  so that the plurality of coils  120  outputs the magnetic field corresponding to the power of 200 watt (W) in response to the input of “level  2 ”. 
     The cooking apparatus  100  identifies whether the sum of the power of the first coil  121  and the second coil  122  is greater than the reference power ( 1020 ). 
     The controller  140  may identify required power of the first coil and required power of the second coil  122  based on the user input that is input through the user interface  110 , and the controller  140  may compare a sum of the required power of the first coil and the required power of the second coil  122  with the reference power. 
     At this time, the reference power may be defined as power that can be supplied from the external power supplies PS 1  and PS 2 . For example, when the first external power supply PS 1  and the second external power supply PS 2  each is capable of supplying 3.5 kW (for example, rated voltage: 220 V and maximum current: 16 A), the reference power may be set to 3.5 kW. 
     When the sum of the power of the first coil  121  and the power of the second coil  122  is greater than the reference power (yes in  1020 ), the cooking apparatus  100  connects the first rectifier  221  to the first external power supply PS 1  and connects the second rectifier  222  to the second external power supply PS 2  ( 1030 ). 
     When the first and second coils  121  and  122  are supplied with power from the first external power supply PS 1  and when the sum of the required power of the first coil  121  and the required power of the second coil  122  is greater than the reference power, the first coil  121  and the second coil  122  may fail to generate the magnetic field B having the magnitude required by the user. 
     In order to prevent this, the controller  140  may connect the first coil  121  to the first external power supply PS 1  and may connect the second coil  122  to the second external power supply PS 2 . For example, as illustrated in  FIG. 14 , the controller  140  may control the first switch module  211  so that the first positive terminal P 1  is connected to the first phase terminal L 1  and the controller  140  may control the second switch module  212  so that the second positive terminal P 2  is connected to the second phase terminal L 2 . 
     Accordingly, the first coil  121  and the second coil  122  may be supplied with power from the first external power supply PS 1  and the second external power supply PS 2 , respectively. Further, the first coil  121  and the second coil  122  may be supplied with the maximum power from the first external power supply PS 1  and the second external power supply PS 2 , respectively, and thus the maximum magnitude of the magnetic field B generated by the first coil  121  and the second coil  122  may be increased. 
     The cooking apparatus  100  identifies whether the power of the first coil  121  is greater than the power of the second coil  122  ( 1040 ). 
     The controller  140  may identify the required power of the first coil  121  and the requested power of the second coil  122  and may compare the required power of the first coil  121  with the required power of the second coil  122 . 
     When the power of the first coil  121  is greater than the power of the second coil  122  (yes in  1040 ), the cooking apparatus  100  connects the third and fourth rectifiers  223  and  224  to the second external power supply PS 2  ( 1050 ). 
     Because the controller  140  connects the first rectifier  221  and the second rectifier  222  to the first external power supply PS 1  and the second external power supply PS 2 , respectively, the third rectifier  223  and the fourth rectifier  224  may be disconnected from the external power supply PS. 
     The controller  140  may control the switching circuit  131  so that any one of the first external power supply PS 1  or the second external power supply PS 2  supplies power to the third coil  123  and the fourth coil  124 , thereby allowing a user to use the third coil  123  and the fourth coil  124 . Particularly, the controller  140  may control the switching circuit  131  so that a power supply, which is connected to any one requiring less power between the first coil  121  and the second coil  122 , supplies power to the third coil  123  and the fourth coil  124 , and thereby the power is stably supplied to the first coil  121  and the second coil  122 . 
     Particularly, when required power of the second coil  122  is less than required power of the first coil  121 , the controller  140  may control the switching circuit  131  so that the second external power supply PS 2  connected to the second coil  122  supplies power to the third coil  123  and the fourth coil  124 . For example, the controller  140  may control the third switch module  213  so that the third positive terminal P 3  is connected to the second phase terminal L 2  and may control the fourth switch module  214  so that the fourth positive terminal P 4  is connected to the second phase terminal L 2 . 
     When the power of the first coil  121  is not greater than the power of the second coil  122  (no in  1040 ), the cooking apparatus  100  may connect the third and fourth rectifiers  223  and  224  to the first external power supply PS 1  ( 1060 ). 
     When the required power of the first coil  121  is less than the required power of the second coil  122 , the controller  140  may control the switching circuit  131  so that the first external power supply PS 1  connected to the first coil  121  supplies power to the third coil  123  and the fourth coil  124 . For example, the controller  140  may control the third switch module  213  so that the third positive terminal P 3  is connected to the first phase terminal L 1  and may control the fourth switch module  214  so that the fourth positive terminal P 4  is connected to the first phase terminal L 1 . 
     As mentioned above, when the sum of the required power of the first coil  121  and the required power of the second coil  122  exceeds the reference power (the maximum power of the external power supply), the cooking apparatus  100  may supply power from the first external power supply PS 1  and the second external power supply PS 2  to the first coil  121  and the second coil  122 , respectively. Therefore, a maximum output of the first coil  121  and a maximum output of the second coil  122  may be increased to a maximum power supply of the first external power supply PS 1  and a maximum power supply of the second external power supply PS 2 , respectively. 
     When the sum of the power of the first coil  121  and the power of the second coil  122  is not greater than the reference power (no in  1020 ), the cooking apparatus  100  identifies whether the sum of the power of the third coil  123  and the power of the fourth coil  124  is greater than the reference power ( 1070 ). 
     The controller  140  may identify required power of the third coil  123  and required power of the fourth coil  124  based on the user input that is input through the user interface  110 , and the controller  140  may compare a sum of the required power of the third coil  123  and the required power of the fourth coil  124  with the reference power. 
     When the sum of the power of the third coil  123  and the power of the fourth coil  124  is greater than the reference power (yes in  1070 ), the cooking apparatus  100  connects the third rectifier  223  to the first external power supply PS 1  and connects the fourth rectifier  224  to the second external power supply PS 2  ( 1080 ). 
     When the third and fourth coils  123  and  123  are supplied with power from the second external power supply PS 2  and when the sum of the required power of the third coil  123  and the required power of the fourth coil  124  is greater than the reference power, the third coil  123  and the fourth coil  124  may fail to generate the magnetic field B having the magnitude required by the user. 
     In order to prevent this, the controller  140  may connect the third coil  123  to the first external power supply PS 1  and may connect the fourth coil  124  to the second external power supply PS 2 . For example, as illustrated in  FIG. 15 , the controller  140  may control the third switch module  213  so that the third positive terminal P 3  is connected to the first phase terminal L 1  and the controller  140  may control the fourth switch module  214  so that the fourth positive terminal P 4  is connected to the second phase terminal L 2 . 
     Accordingly, the third coil  123  and the fourth coil  124  may be supplied with power from the first external power supply PS 1  and the second external power supply PS 2 , respectively. Further, the third coil  123  and the fourth coil  124  may be supplied with the maximum power from the first external power supply PS 1  and the second external power supply PS 2 , respectively, and thus the maximum magnitude of the magnetic field B generated by the third coil  123  and the fourth coil  124  may be increased. 
     The cooking apparatus  100  identifies whether the power of the third coil  123  is greater than the power of the fourth coil  124  ( 1090 ). 
     When the power of the third coil  123  is greater than the power of the fourth coil  124  (yes in  1090 ), the cooking apparatus  100  connects the first and second rectifiers  221  and  222  to the second external power supply PS 2  ( 1100 ). 
     In the operation  1100 , the controller  140  may control the first switch module  211  so that the first positive terminal P 1  is connected to the first phase terminal L 1  and the controller  140  may control the second switch module  212  so that the second positive terminal P 2  is connected to the second phase terminal L 2  in the same manner as that of the operation  1050 . 
     When the power of the third coil  123  is not greater than the power of the fourth coil  124  (no in  1090 ), the cooking apparatus  100  may connect the first and second rectifiers  221  and  222  to the first external power supply PS 1  ( 1110 ). 
     In the operation  1110 , the controller  140  may control the first switch module  211  so that the first positive terminal P 1  is connected to the first phase terminal L 1  and the controller  140  may control the second switch module  212  so that the second positive terminal P 2  is connected to the first phase terminal L 1  in the same manner as that of the operation  1060 . 
     When the sum of the power of the third coil  123  and the power of the fourth coil  124  is not greater than the reference power (no in  1070 ), the cooking apparatus  100  may connect the first and second rectifiers  221  and  222  to the first external power supply PS 1  and may connect the third and fourth rectifiers  223  and  224  to the second external power supply PS 2  ( 1120 ). 
     In order to stably supply power to the first, second, third, and fourth coils  121 ,  122 ,  123 , and  124  from the first and second external power supplies PS 1  and PS 2 , the cooking apparatus  100  may evenly distribute the first and second external power supplies PS 1  and PS 2  to the first, second, third, and fourth coils  121 ,  122 ,  123  and  124 . The cooking apparatus  100  may supply power from the first external power supply PS 1  to the first and second coils  121  and  122  located in the left column of the cooking plate  102 , and may supply power from the second external power supply PS 2  to the third and fourth coils  123  and  124  located in the right column of the cooking plate  102 . 
     For example, the controller  140  may control the first and second switch modules  211  and  212  so that the first and second positive terminals P 1  and P 2  are connected to the first phase terminal L 1 , and the controller  140  may control the third and fourth switch modules  213  and  214  so that the third and fourth positive terminals P 3  and P 4  are connected to the second phase terminal L 2 . 
     As mentioned above, the cooking apparatus  100  may stably supply power to the first and second coils  121  and  122  and the third and fourth coils  123  and  124  by supplying power to the first and second coils  121  and  122  from the first external power supply PS 1  and by supplying power to the third and fourth coils  123  and  124  from the second external power supply PS 2 . 
     Further, when the sum of the required power of the first coil  121  and the requested power of the second coil  122  is greater than the reference power (the maximum power that can be supplied by the external power supply), the cooking apparatus  100  may supply the power from the first external power supply PS 1  to the first coil  121  and supply the power from the second external power supply PS 2  to the second coil  122 , thereby increasing the maximum output of the first and second coils  121  and  122 . The cooking apparatus  100  may increase the maximum power of the third and fourth coils  123  and  124  in the same manner. 
       FIG. 16  illustrates a view of another example of the driver contained in the cooking apparatus according to an embodiment of the disclosure. 
     As illustrated in  FIG. 16 , the driver  130  includes a plurality of inverters  230 , a plurality of rectifiers  220 , and a switching circuit  131 . The external power supply PS includes a first external power supply PS 1  and a second external power supply PS 2  for supplying AC power having different phases. 
     The plurality of inverters  230  may include first, second, third, and fourth inverters  231 ,  232 ,  233 , and  234  supplying a drive current to first, second, third, and fourth coils  121 ,  122 ,  123  and  124 , respectively. 
     The plurality of rectifiers  220  may include a first rectifier  221  supplying DC power to the first inverter  231 , a second rectifier  222  supplying DC power to the second inverter  232 , and a third rectifier  223  supplying DC power to the third and fourth inverters  233  and  234 . 
     As mentioned above, the first rectifier  221  and the first inverter  231  may be connected on a one-to-one basis. Therefore, the cooking apparatus  100  may supply the maximum power from the first external power supply PS 1  and the second external power supply PS 2  to the first inverter  231  and the second inverter  232 , respectively. 
     The third rectifier  223  may supply DC power to the third and fourth inverters  233  and  234 , and the third and fourth coils  123  and  124  receiving the drive current from the third and fourth inverters  233  and  234  may operate as a subgroup. Further, because an additional rectifier for supplying DC power to the fourth inverter  234  is omitted, the number of rectifiers may be reduced and the cost of the product may be reduced. 
     The third and fourth coils  123  and  124  may still operate as two or one burner by separately receiving the drive current from the third and fourth inverters  233  and  234 . 
     The switching circuit  131  may connect each of the first, second and third rectifiers  221 ,  222  and  223  to a corresponding one of the first external power supply PS 1  or the second external power supply PS 2 . For example, the switching circuit  131  may connect the first and second rectifiers  221  and  222  to the first external power supply PS 1  and may connect the third rectifier  223  to the second external power supply PS 2 . Accordingly, it is possible to supply power to the first and second coils  121  and  122 , and the third and fourth coils  123  and  124  independently of each other. 
     The number of the plurality of coils  120 , the plurality of inverters  230 , and the plurality of rectifiers  220  is not limited thereto. 
       FIG. 17  illustrates a view of an interior of the cooking apparatus according to an embodiment of the disclosure.  FIG. 18  illustrates a view of an example of a driver contained in the cooking apparatus according to an embodiment of the disclosure.  FIG. 19  illustrates a view of an example of a switching circuit contained in the cooking apparatus according to an embodiment of the disclosure. 
     Referring to  FIGS. 17 to 19 , the cooking apparatus  100  includes a plurality of coils  120 , a driver  130  and a controller  140 . 
     The plurality of coils  120  includes fifth, sixth, seventh, eighth, ninth, tenth, eleventh and twelfth coils  125 ,  126 ,  127 ,  128 ,  129 ,  129   a ,  129   b , and  129   c . The plurality of coils  120  each may be installed under the cooking plate  102  to generate a magnetic field and/or an electric field and/or an electromagnetic field for heating the cooking vessel  1 . 
     As illustrated in  FIG. 17 , the plurality of coils  120  may be arranged in a predetermined pattern under the cooking plate  102 . For example, the fifth, sixth, seventh and eighth coils  125 ,  126 ,  127  and  128  may be arranged in a first column (a left column of the cooking plate) and the ninth, tenth, eleventh and twelfth coils  129 ,  129   a ,  129   b , and  129   c  may be arranged in a second column (a right column of the cooking plate). 
     The fifth to twelfth coils  125  to  129   c  may have magnitudes and numbers of turns different from those of the first to fourth coils  121  to  124  illustrated in  FIG. 2 . In other words, the fifth to twelfth coils  125  to  129   c  may have inductances different from those of the first to fourth coils  121  to  124  illustrated in  FIG. 2 . 
     The driver  130  may be supplied with power from the external power supply PS and may supply the drive current to the plurality of coils  120  according to the driving control signal of the controller  140 . Particularly, according to the control signal of the controller  140 , the driver circuit  133  may apply an AC voltage and output an AC (drive current) to the plurality of coils  120 . 
     As illustrated in  FIG. 18 , the driver  130  includes a plurality of inverters  230 , a plurality of rectifier  220  and the switching circuit  131 . 
     The plurality of inverters  230  may be supplied with a DC voltage and a DC from the plurality of rectifiers  220 , respectively and may apply an AC voltage and supply an AC to each of the plurality of coils  120 , respectively. 
     The plurality of inverters  230  may include a fifth inverter  235  supplying a drive current to the fifth coil  125 , a sixth inverter  236  supplying a drive current to the sixth coil  126 , a seventh inverter  237  supplying a drive current to the seventh coil  127 , an eighth inverter  238  supplying a drive current to the eighth coil  128 , a ninth inverter  239  supplying a drive current to the ninth coil  129 , a tenth inverter  239   a  supplying a drive current to the tenth coil  129   a , an eleventh inverter  239   b  supplying a drive current to the eleventh coil  129   b , and a twelfth inverter  239   c  supplying a drive current to the twelfth coil  129   c.    
     At this time, the fifth to twelfth inverters  235  to  239   c  may supply a maximum AC, which is different from the first to fourth inverters  231  to  234  illustrated in  FIG. 6 , to the plurality of coils  120 . 
     The plurality of rectifiers  220 :  225 ,  226 ,  227 ,  228 ,  229 ,  229   a ,  229   b , and  229   c  may apply the DC voltage and supply the DC to the plurality of inverters  235 ,  236 ,  237 ,  238 ,  239 ,  239   a ,  239   b , and  239   c , respectively. 
     The plurality of rectifiers  220  may include a fifth rectifier  225  supplying DC power to the fifth inverter  235 , a sixth rectifier  226  supplying DC power to the sixth inverter  236 , a seventh rectifier  227  supplying DC power to the seventh inverter  237 , an eighth rectifier  228  supplying DC power to the eighth inverter  238 , a ninth rectifier  229  supplying DC power the ninth inverter  239 , a tenth rectifier  229   a  supplying DC power to the tenth inverter  239   a , an eleventh rectifier  229   b  supplying DC power to the eleventh inverter  239   b , and a twelfth rectifier  229   c  supplying DC power to the twelfth inverter  239   c.    
     At this time, the fifth to twelfth rectifiers  225  to  229   c  may supply a maximum DC, which is different from the first to fourth rectifiers  221  to  224  illustrated in  FIG. 6 , to the plurality of inverters  230 . 
     The external power supply PS may include a first external power supply PS 1  and a second external power supply PS 2  for supplying AC power having different phases to the cooking apparatus  100 . 
     As illustrated in  FIG. 19 , the switching circuit  131  may selectively connect the plurality of rectifiers  220  to the external power supply PS. Particularly, the switching circuit  131  may selectively connect the fifth to twelfth rectifiers  225  to  229   c  to the first external power supply PS 1  or the second external power supply PS 2 . For example, under the control of the controller  140 , the switching circuit  131  may connect the fifth, sixth, seventh and eighth rectifiers  225 ,  226 ,  227  and  228  to the first external power supply PS 1 , and may connect the ninth, tenth, eleventh, and twelfth rectifiers  229 ,  229   a ,  229   b , and  229   c  to the second external power supply PS 2 . 
     The switching circuit  131  may be connected to the first and second external power supplies PS 1  and PS 2  and may be connected to the fifth to twelfth rectifiers  225  to  229   c . The switching circuit  131  may include first and second phase terminals L 1  and L 2  and a neutral terminal N connected to the first and second external power supplies PS 1  and PS 2 , respectively. Further, the switching circuit  131  may include fifth, sixth, seventh, eighth, ninth, tenth, and eleventh positive/negative terminals P 5 /N 5 , P 6 /N 6 , P 7 /N 7 , P 8 /N 8 , P 9 /N 9 , P 10 /N 10 , P 11 /N 11 , and P 12 /N 12  connected to the fifth, sixth, seventh, eighth, ninth, tenth, eleventh and twelfth rectifiers  225 ,  226 ,  227 ,  228 ,  229 ,  229   a ,  229   b  and  229   c , respectively. 
     The fifth to twelfth negative terminals N 5  to N 12  may be connected to the neutral terminal N of the external power supply PS. 
     The switching circuit  131  may include a plurality of switch modules  210 :  215 ,  216 ,  217 ,  217 ,  219 ,  219   a ,  219   b , and  219   c  connecting selectively the fifth to twelfth terminals P 5  to P 12  to the first phase terminal L 1  or the second phase terminals L 2 . 
     The plurality of switch modules  210  may include a fifth switch module  215  connected to the fifth positive terminal P 5 , a sixth switch module  216  connected to the sixth positive terminal P 6 , a seventh switch module  217  connected to the seventh positive terminal P 7 , an eighth switch module  218  connected to the eighth positive terminal P 8 , a ninth switch module  219  connected to the ninth positive terminal P 9 , a tenth switch module  219   a  connected to the tenth positive terminal P 10 , an eleventh switch module  219   b  connected to the eleventh positive terminal P 11  and a twelfth switch module  219   c  connected to the twelfth positive terminal P 12 . 
     According to the control signal of the controller  140 , the fifth to twelfth switch modules  215  to  219   c  may connect each of the fifth to twelfth positive terminals P 5  to P 12  to a corresponding one of the first phase terminal L 1  or the second phase terminal L 2 . 
     For example, the controller  140  may control the fifth, sixth, seventh, and eighth switch modules  215 ,  216 ,  217  and  218  so that the fifth, sixth, seventh, and eighth positive terminals P 5 , P 6 , P 7 , and P 8  are connected to the first phase terminal L 1 . The controller  140  may control the ninth, tenth, eleventh and twelfth switch modules  219 ,  219   a ,  219   b , and  219   c  so that the ninth, tenth, eleventh and twelfth positive terminals P 9 , P 10 , P 11  and P 12  is connected to the second phase terminal L 2 . 
     Accordingly, power may be evenly supplied to the fifth to twelfth coils  125  to  129   c  from the first and second external power supplies PS 1  and PS 2 . 
     Further, the fifth, sixth, seventh and eighth coils  125 ,  126 ,  127 , and  128  arranged in the left column may operate as four, three, two, or one burner, depending on a user input. The ninth, tenth, eleventh and twelfth coils  129 ,  129   a ,  129   b  and  129   c  arranged in the right column may also operate as two or one burner depending on a user input. 
     According to the output of the coils  125  to  129   c , the controller  140  may change the connection between the fifth to twelfth terminals P 5  to P 12  and the first and second phase terminals L 1  and L 2 . For example, when the fifth coil  125  and the sixth coil  126  operate simultaneously and when the sum of the output of the fifth coil  125  and the output of the sixth coil  126  is greater than the reference output, the controller  140  may control the fifth switch module  215  so that the fifth positive terminal P 5  is connected to the first phase terminal L 1 , and may control the sixth switch module  216  so that the sixth positive terminal P 6  is connected to the second phase terminal L 2 . The controller  140  may control other switch module in the same manner. 
     Accordingly, a maximum output of a coil on which a load is concentrated, among the plurality of coils  120  may be increased. For example, when the load is concentrated on the fifth and sixth coils  125  and  126 , the controller  140  may supply power to the fifth and sixth coils  125  and  126  from the first and second power supplies PS 1  and PS 2 , respectively. 
     As mentioned above, the cooking apparatus  100  may control eight coils  125  to  129   c  independently of each other by using eight inverters  235  to  239   c  supplying the drive current to the eight coils  125  to  129   c , respectively. Because the eight inverters  235  to  239   c  correspond to eight rectifiers  225  to  229   c  on a one-to-one basis, the cooking apparatus  100  may supply power to the eight coils  125  to  129   c  independently of each other. Further, by using the switching circuit  131  connecting each of the eight rectifiers  225  to  229   c  to a corresponding one of the first power supply PS 1  or the second power supply PS 2 , the cooking apparatus  100  may increase the maximum power supplied to the eight coils  125  to  129   c.    
       FIG. 20  illustrates a view of another example of the driver contained in the cooking apparatus according to an embodiment of the disclosure. 
     Referring to  FIG. 20 , the cooking apparatus  100  includes a plurality of coils  120 , a driver  130 , and a controller  140 . 
     The plurality of coils  120 :  125 ,  126 ,  127 ,  128 ,  129 ,  129   a ,  129   b , and  129   c  includes fifth, sixth, seventh and eighth coils  125 ,  126 ,  127  and  128  arranged in a first column (a left column of the cooking plate) and ninth, tenth, eleventh and twelfth coils  129 ,  129   a ,  129   b  and  129   c  arranged in a second column (a right column of the cooking plate). The fifth to twelfth coils  125  to  129   c  may have inductances different from those of the first to fourth coils  121  to  124  illustrated in  FIG. 2 . 
     The driver  130  includes a plurality of inverters  230 , a plurality of rectifiers  220 , and a switching circuit  131 . 
     The plurality of inverters  230  may include a first inverter  231  supplying a drive current to the fifth and sixth coils  125  and  126 , a second inverter  231  supplying a drive current to the seventh and eighth coils  127  and  128 , a third inverter  233  supplying a drive current to the ninth and tenth coils  129  and  129   a  and a fourth inverter  234  supplying a drive current to the eleventh and twelfth coils  129   a  and  129   b.    
     According to a control signal of the controller  140 , each of the plurality of inverters  231 ,  232 ,  233  and  234  may supply a drive current to corresponding designated two coils  125  and  126 ,  127  and  127  and  128 ,  129  and  129   a , and  129   b  and  129   c  or a corresponding one of designated two coils  125  and  126 ,  127  and  127  and  128 ,  129  and  129   a , and  129   b  and  129   c . For example, the first inverter  231  may supply the drive current to both of the fifth and sixth coils  125  and  126 , or may supply the drive current to one of the fifth and sixth coils  125  and  126 . The second inverter  232  may supply the drive current to both of the seventh and eighth coils  127  and  128  or may supply the drive current to one of the seventh and eighth coils  127  and  128 . The third inverter  233  may supply the drive current to both of the ninth and tenth coils  129  and  129   a  or may supply the drive current to one of the ninth and tenth coils  129  and  129   a . Under the control of the controller  140 , the fourth inverter  234  may supply the drive current to both of the eleventh and twelfth coils  129   b  and  129   c  or may supply the drive current to one of the eleventh and twelfth coils  129   b  and  129   c.    
     The plurality of rectifiers  220  may include a first rectifier  221  supplying DC power to the first inverter  231 , a second rectifier  222  supplying DC power to the second inverter  232 , a third rectifier  223  supplying DC power to the third inverter  233  and a fourth rectifier  224  supplying DC power to the fourth inverter  234 . 
     The switching circuit  131  may selectively connect the first, second, third and fourth rectifiers  221 ,  222 ,  223  and  224  to the first power supply PS 1  or the second power supply PS 2 . For example, under the control of the controller  140 , the switching circuit  131  may connect the first and second rectifiers  221  and  222  to the first power supply PS 1 , and may connect the third and fourth rectifiers  223  and  224  to the second power supply PS 2 . 
     As mentioned above, because the four inverters  231  to  235  correspond to the four rectifiers  221  to  224  on a one-to-one basis, the cooking apparatus  100  may supply power to the eight coils  125  to  129   c  independently of each other. Further, by using the switching circuit  131  connecting each of the four rectifiers  221  to  224  to a corresponding one of the first power supply PS 1  or the second power supply PS 2 , the cooking apparatus  100  may increase the maximum power supplied to the eight coils  125  to  129   c.    
       FIG. 21  illustrates a view of another example of the driver contained in the cooking apparatus according to an embodiment of the disclosure. 
     Referring to  FIG. 21 , a cooking apparatus  100  includes a plurality of coils  120 , a driver  130 , and a controller  140 . 
     The plurality of coils  120  may include fifth, sixth, seventh, eighth, ninth, tenth, eleventh and twelfth coils  125 ,  126 ,  127 ,  128 ,  129 ,  129   a ,  129   b , and  129   c , and a configuration and an operation of the plurality of coils  120  may be the same as the plurality of coils illustrated in  FIG. 2 . 
     The driver  130  includes a plurality of inverters  230 , a plurality of rectifiers  220 , and a switching circuit  131 . 
     The plurality of inverters  230  may include fifth, sixth, seventh, and eighth inverters  235 ,  236 ,  237  and  238  respectively supplying a drive current to the fifth, sixth, seventh, and eighth coils  125 ,  126 ,  127 , and  128  in the left column, a third inverter  233  supplying a drive current to the ninth and tenth coils  129  and  129   a , and a fourth inverter  234  supplying a drive current to the eleventh and twelfth coils  129   b  and  129   c.    
     An operation of the fifth, sixth, seventh and eighth inverters  235 ,  236 ,  237  and  238  may be the same as the operation of the fifth, sixth, seventh and eighth inverters illustrated in  FIG. 18 . 
     An operation of the third and fourth inverters  233  and  234  may be the same as the operation of the third and fourth inverters illustrated in  FIG. 20 . 
     The plurality of rectifiers  220  may include fifth, sixth, seventh, eighth, third and fourth rectifiers  225 ,  226 ,  227 ,  228 ,  223 , and  224  respectively supplying DC power to the fifth, sixth, seventh, eighth, third and fourth inverters  235 ,  236 ,  237 ,  238 ,  233 , and  234 . 
     The switching circuit  131  may selectively connect the fifth, sixth, seventh, eighth, third and fourth rectifiers  225 ,  226 ,  227 ,  228 ,  223 , and  224  to the first power supply PS 1  or the second power supply PS 2 . For example, under the control of the controller  140 , the switching circuit  131  may connect the fifth, sixth, seventh and eighth rectifiers  225 ,  226 ,  227  and  228  to the first power supply PS 1  and may connect the third and fourth rectifiers  223 , and  224  to the second power supply PS 2 . 
     As mentioned above, because the six inverters  235 ,  236 ,  237 ,  238 ,  233 , and  234  correspond to the six rectifiers  225 ,  226 ,  227 ,  228 ,  223 , and  224  on a one-to-one basis, the cooking apparatus  100  may supply power to the eight coils  125  to  129   c  independently of each other. Further, by using the switching circuit  131  connecting each of the six rectifiers  225 ,  226 ,  227 ,  228 ,  223 , and  224  to a corresponding one of the first power supply PS 1  or the second power supply PS 2 , the cooking apparatus  100  may increase the maximum power supplied to the eight coils  125  to  129   c.    
       FIG. 22  illustrates a view of another example of the driver contained in the cooking apparatus according to an embodiment of the disclosure. 
     Referring to  FIG. 22 , the cooking apparatus  100  includes a plurality of coils  120 , a driver  130 , and a controller  140 . 
     The plurality of coils  120  may include fifth, sixth, seventh, eighth, ninth, tenth, eleventh and twelfth coils  125 ,  126 ,  127 ,  128 ,  129 ,  129   a ,  129   b , and  129   c , and a configuration and an operation of the plurality of coils  120  may be the same as the plurality of coils illustrated in  FIG. 20 . 
     The driver  130  includes a plurality of inverters  230 , a plurality of rectifiers  220 , and a switching circuit  131 . 
     The plurality of inverters  230  may include fifth, sixth, seventh, eighth, third and fourth inverters  235 ,  236 ,  237 ,  238 ,  233 , and  234  and a configuration and an operation of the plurality of inverters  230  may be the same as the plurality of inverters of  FIG. 21 . 
     The plurality of rectifiers  220  may include fifth, sixth, seventh, and eighth, rectifiers  225 ,  226 ,  227 , and  228  respectively supplying DC power to the fifth, sixth, seventh, and eighth inverters  235 ,  236 ,  237 , and  238 , and a third rectifier  223  supplying DC power to the third and fourth inverters  233  and  234 . Accordingly, the third rectifier  223  may supply the DC power to the third and fourth inverters  233  and  234 , thereby reducing the number of rectifiers and reducing the cost of the product. 
     Because the third and fourth inverters  233  and  234  are supplied with DC power from the third rectifier  223 , the ninth, tenth, eleventh, and twelfth coils  129 ,  129   a ,  129   b , and  129   c  may operate as a subgroup. By respectively receiving the drive current from the third and fourth inverters  233  and  234 , the ninth, tenth, eleventh, and twelfth coils  129 ,  129   a ,  129   b , and  129   c  may operate as four, three, two or a single burner. 
     The switching circuit  131  may connect each of the fifth, sixth, seventh, eighth and third rectifiers  225 ,  226 ,  227 ,  228  and  223  to a corresponding one of the first external power supply PS 1  or the second external power supply PS 2 . For example, the switching circuit  131  may connect the fifth, sixth, seventh and eighth rectifiers  225 ,  226 ,  227  and  228  to the first external power supply PS 1  and may connect the third rectifier  223  to the second external power supply PS 2 . 
     As mentioned above, because the single rectifier  223  supplies the DC power to the two inverters  233  and  234 , it is possible to omit a single rectifier that is to supply the DC power to the inverter, thereby reducing the number of rectifiers and reducing the cost of the product. 
       FIG. 23  illustrates a view of another example of the driver contained in the cooking apparatus according to an embodiment of the disclosure. 
     Referring to  FIG. 23 , the cooking apparatus  100  includes a plurality of coils  120 , a driver  130 , and a controller  140 . 
     The plurality of coils  120  may include first, seventh, eighth, third, eleventh and twelfth coils  121 ,  127 ,  128 ,  123 ,  129   b , and  129   c.    
     The plurality of coils  120  may be arranged in a predetermined pattern under the cooking plate  102 . For example, the first, seventh and eighth coils  121 ,  127  and  128  may be arranged in a first column (a left column of the cooking plate) and the third, eleventh and twelfth coils  123 ,  129   b , and  129   c  may be arranged in a second column (a right column of the cooking plate). 
     The first and third coils  121  and  123  may have inductances different from those of the seventh, eighth, eleventh and twelfth coils  127 ,  128 ,  129   b  and  129   c.    
     The driver  130  includes a plurality of inverters  230 , a plurality of rectifiers  220 , and a switching circuit  131 . 
     The plurality of inverters  230  may include a first inverter  231  supplying a drive current to the first coil  121 , a seventh inverter  237  supplying a drive current to the seventh coil  127 , an eighth inverter  238  supplying a drive current to the eighth coil  128 , a third inverter  233  supplying a drive current to the third coil  123 , and an eleventh inverter  239   b  supplying a drive current to the eleventh coil  129   b  and a twelfth inverter  239   c  supplying a drive current to the twelfth coil  129   c.    
     The first and third inverters  231  and  233  and the seventh, eighth, eleventh and twelfth inverters  237 ,  238 ,  239   b  and  239   c  may supply a different maximum AC to the plurality of coils  120 . 
     The plurality of rectifiers  220  may include a first rectifier  221  supplying DC power to the first inverter  231 , a seventh rectifier  227  supplying DC power to the seventh inverter  237 , an eighth rectifier  228  supplying DC power to the eight inverter  238 , a third rectifier  223  supplying DC power DC power to the third inverter  233 , an eleventh rectifier  229   b  supplying DC power to the eleventh inverter  239   b , and a twelfth rectifier  229   c  supplying DC power to the twelfth inverter  239   c.    
     The first and third inverters  231  and  233  and the seventh, eighth, eleventh and twelfth inverters  237 ,  238 ,  239   b  and  239   c  may supply a different maximum DC to the plurality of inverters  230 . 
     The switching circuit  131  may selectively connect the first, third, seventh, eighth, eleventh and twelfth rectifiers  221 ,  223 ,  227 ,  228 ,  229   b  and  229   c  to the first power supply PS 1  or the second power supply PS 2 . For example, under control of the controller  140 , the switching circuit  131  may connect the first, seventh, and eighth rectifiers  221 ,  227 , and  228  to the first power supply PS 1 , and may connect the third, eleventh, and twelfth rectifiers  223 ,  229   b , and  229   c  to the second power supply PS 2 . 
     As mentioned above, by using the six inverters  231 ,  237 ,  238 ,  233 ,  239   b , and  239   c , the cooking apparatus  100  may control the six coils  121 ,  127 ,  128 ,  123 ,  129   b , and  129   c  independently of each other. Because the six inverters  231 ,  237 ,  238 ,  233 ,  239   b , and  239   c  correspond to the six rectifiers  221 ,  227 ,  228 ,  223 ,  229   b , and  229   c  on a one-to-one basis, the cooking apparatus  100  may supply power to the six coils  121 ,  127 ,  128 ,  123 ,  129   b , and  129   c  independently of each other. Further, by using the switching circuit  131  connecting each of the six rectifiers  221 ,  227 ,  228 ,  223 ,  229   b , and  229   c  to a corresponding one of the first power supply PS 1  or the second power supply PS 2 , the cooking apparatus  100  may increase the maximum power supplied to the six coils  121 ,  127 ,  128 ,  123 ,  129   b , and  129   c.    
       FIG. 24  illustrates a view of another example of the driver contained in the cooking apparatus according to an embodiment of the disclosure. 
     Referring to  FIG. 24 , the cooking apparatus  100  includes a plurality of coils  120 , a driver  130 , and a controller  140 . 
     The plurality of coils  120  may include first, third, seventh, eighth, eleventh and twelfth coils  121 ,  123 ,  127 ,  128 ,  129   b , and  129   c , and a configuration and an operation of the plurality of coils  120  may be the same as the plurality of coils illustrated in  FIG. 23 . 
     The driver  130  includes a plurality of inverters  230 , a plurality of rectifiers  220 , and a switching circuit  131 . 
     The plurality of inverters  230  may include a first inverter  231  supplying a drive current to the first coil  121 , a seventh inverter  237  supplying a drive current to the seventh coil  127 , an eighth inverter  238  supplying a drive current to the eighth coil  128 , a third inverter  233  supplying a drive current to the third coil  123 , and a fourth inverter  234  supplying a drive current to the eleventh and twelfth coils  129   b  and  129   c.    
     The first, third, seventh and eighth inverters  231 ,  233 ,  237  and  238  may supply the drive current to the first, third, seventh and eighth coils  121 ,  123 ,  127  and  128 , respectively. Under the control of the controller  140 , the fourth inverter  234  may supply the drive current to the eleventh and twelfth coils  129   b  and  129   c  or may supply the drive current to one of the eleventh and twelfth coils  129   b  and  129   c.    
     The plurality of rectifiers  220  may include a first rectifier  221  supplying DC power to the first inverter  231 , a seventh rectifier  227  supplying DC power to the seventh inverter  237 , an eighth rectifier  228  supplying DC power to the eighth inverter  238 , a third rectifier  223  supplying DC power to the third inverter  233 , and a fourth rectifier  224  supplying DC power to the fourth inverter  234 . 
     The switching circuit  131  may selectively connect the first, seventh, eighth, third and fourth rectifiers  221 ,  227 ,  228 ,  223  and  224  to the first power supply PS 1  or the second power supply PS 2 . For example, under control of the controller  140 , the switching circuit  131  may connect the first, seventh, and eighth rectifiers  221 ,  227 , and  228  to the first power supply PS 1  and may connect the third and fourth rectifiers  223  and  234  to the second power supply PS 2 . 
     As mentioned above, because the five inverters  231 ,  237 ,  238 ,  233 , and  234  correspond to the five rectifiers  221 ,  227 ,  228 ,  223 , and  224  on a one-to-one basis, the cooking apparatus  100  may supply power to the six coils  121 ,  127 ,  128 ,  123 ,  129   b , and  129   c  independently of each other. Further, by using the switching circuit  131  connecting each of the five rectifiers  221 ,  227 ,  228 ,  223 , and  224  to a corresponding one of the first power supply PS 1  or the second power supply PS 2 , the cooking apparatus  100  may increase the maximum power supplied to the six coils  121 ,  127 ,  128 ,  123 ,  129   b , and  129   c.    
       FIG. 25  illustrates a view of another example of the driver contained in the cooking apparatus according to an embodiment of the disclosure. 
     Referring to  FIG. 25 , the cooking apparatus  100  includes a plurality of coils  120 , a driver  130 , and a controller  140 . 
     The plurality of coils  120  may include first, third, seventh, eighth, eleventh and twelfth coils  121 ,  123 ,  127 ,  128 ,  129   b , and  129   c , and a configuration and an operation of the plurality of coils  120  may be the same as the plurality of coils of  FIG. 23 . 
     The driver  130  includes a plurality of inverters  230 , a plurality of rectifiers  220 , and a switching circuit  131 . 
     The plurality of inverters  230  may include first, seventh, eighth, third and fourth inverters  231 ,  237 ,  237 ,  233 , and  234 , and a configuration and an operation of the plurality of inverters  230  may be the same as the plurality of inverters of  FIG. 21 . 
     The plurality of rectifiers  220  may include first, seventh and eighth rectifiers  221 ,  227  and  228  respectively supplying DC power to the first, seventh and eighth inverters  231 ,  237 , and  238 , and a third rectifier  223  supplying DC power to the third and fourth inverters  233  and  234 . Accordingly, the third rectifier  223  may supply DC power to the third and fourth inverters  233  and  234 , thereby reducing the number of the rectifiers and the cost of the product. 
     Because the third and fourth inverters  233  and  234  are supplied with the DC power from the third rectifier  223 , the third, eleventh and twelfth coils  123 ,  129   b , and  129   c  may operate as a subgroup. Further, by respectively receiving the driver current from the third and fourth inverters  233  and  234 , the third, eleventh and twelfth coils  123 ,  129   b , and  129   c  may operate as three, two or one burner. 
     The switching circuit  131  may connect each of the first, seventh, eighth, and third rectifiers  221 ,  227 ,  228 , and  223  to a corresponding one of the first power supply PS 1  or the second power supply PS 2 . For example, the switching circuit  131  may connect the first, seventh, and eighth rectifiers  221 ,  227 , and  228  to the first power supply PS 1  and may connect the third rectifier  223  to the second power supply PS 2 . 
     As mentioned above, because the single rectifier  223  supplies the DC power to the two inverters  233  and  234 , a single rectifier for supplying the DC power to the inverter is omitted, thereby reducing the number of rectifiers and the cost of the product. 
       FIG. 26  illustrates a view of another example of operation of the power distribution of the cooking apparatus according to an embodiment of the disclosure. 
     Power distribution ( 1200 ) of the cooking apparatus  100  will be described with reference to  FIG. 26 . 
     The cooking apparatus  100  receives a user input from a user ( 1210 ). 
     The cooking apparatus  100  may receive information (or a command) on an output level from the user. 
     The operation  1210  may be identical to the operation  1010  described in conjunction with  FIG. 12 . 
     The cooking apparatus  100  connects the maximum output coil to the first external power supply PS 1  ( 1220 ). 
     The controller  140  may identify required power of the plurality of coils  120  based on the user input that is inputted through the user interface  110 . The controller  140  may identify a maximum output coil having the largest required power based on the required power of the plurality of coils  120 . 
     In addition, the controller  140  may connect the maximum output coil to the first external power supply PS 1 . For example, the controller  140  may control the switching circuit  131  so that the first coil  121  having the largest required power is connected to the first external power supply PS 1 . 
     The cooking apparatus  100  connects the other coils to the second external power supply PS 2  ( 1230 ). 
     Based on the required power of the plurality of coils  120 , the controller  140  may identify the maximum output coil having the largest required power, and identify coils other than the maximum output coil. 
     In addition, the controller  140  may connect coils other than the maximum output coil to the second external power supply PS 2 . For example, the controller  140  may control the switching circuit  131  so that the coils  122 ,  123 , and  124 , which is other than the first coil  121 , is connected to the second external power supply PS 2 . 
     Due to the power distribution operation  1200 , it is possible to stably supply the power to the coil requiring the maximum output and it is possible to increase the maximum output of the plurality of coils  120  to the maximum power that can be supplied from the external power supply PS 1 . 
     As is apparent from the above description, it may be possible to increase a magnitude of a magnetic field output by coils overlapped with a cooking vessel. 
     It may be possible to supply power to each coil overlapped with a cooking vessel from a plurality of external power supplies. 
     It may be possible to supply power to each of a plurality of inverters from each of a plurality of rectifiers. 
     Various embodiments of the present disclosure have been described above. In the various embodiments described above, components may be implemented as a “module”. Here, the term ‘module’ means, but is not limited to, a software and/or hardware component, such as a Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC), which performs certain tasks. A module may advantageously be configured to reside on the addressable storage medium and configured to execute on one or more processors. 
     Thus, a module may include, by way of example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The operations provided for in the components and modules may be combined into fewer components and modules or further separated into additional components and modules. In addition, components and modules may be implemented such that they execute one or more CPUs in a device. 
     With that being said, and in addition to the above described various embodiments, embodiments can thus be implemented through computer readable code/instructions in/on a medium, e.g., a computer readable medium, to control at least one processing element to implement any above described various embodiment. The medium can correspond to any medium/media permitting the storing and/or transmission of the computer readable code. 
     The computer-readable code can be recorded on a medium or transmitted through the Internet. The medium may include Read Only Memory (ROM), Random Access Memory (RAM), Compact Disk-Read Only Memories (CD-ROMs), magnetic tapes, floppy disks, and optical recording medium. Also, the medium may be a non-transitory computer-readable medium. The media may also be a distributed network, so that the computer readable code is stored or transferred and executed in a distributed fashion. Still further, as only an example, the processing element could include at least one processor or at least one computer processor, and processing elements may be distributed and/or included in a single device. 
     While various embodiments have been described with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart, from the scope as disclosed herein. Accordingly, the scope should be limited only by the attached claims. 
     Although the present disclosure has been described with various embodiments, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims.