JP2013161546A - Induction heating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make impedance adjustable and to suppress an increase in cost accompanying upsizing.SOLUTION: An induction heating apparatus includes a heating coil 55, electric power output means of outputting AC electric power, first and second busbars 51, 52 for transmitting the AC electric power from the electric power output means to the heating coil 55, and a variable part 57 for varying at least one of an opposition distance, a length, a width, and an opposition area of the first and second busbars 51, 52.

Description

  The present invention relates to an induction heating apparatus.

  Patent Document 1 below discloses an induction heating device capable of adjusting the impedance on the power feeding side. In the above induction heating device, the winding is composed of a plurality of blocks, and the inductance is variable with the same effect as changing the coil inner diameter by changing the joining state of the blocks and changing the size of the gap surrounded by the blocks. And adjusting the impedance by changing the inductance of the variable coil. Further, Patent Document 2 below includes a variable coil that varies the magnetic permeability by changing the magnetic permeability by sliding the core in the axial direction of the winding with an actuator, and the impedance is varied by varying the inductance of the variable coil. An adjusting induction heating device is disclosed.

JP 2008-287890 A Japanese Patent Laid-Open No. 2004-030965

  By the way, in each of the above prior arts, the inductance on the power feeding side is varied by varying the size of the gap surrounded by the variable coil block on the power feeding side or by sliding the core of the variable coil. When it is necessary to increase the size of the variable coil due to the large value, the problem arises that the variable mechanism becomes large and costs increase. A similar problem occurs even when the impedance is adjusted using a variable capacitor instead of the variable coil.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to adjust the impedance on the power feeding side and suppress an increase in cost associated with an increase in the size of the apparatus.

  In order to achieve the above object, in the present invention, as a first solving means, a heating coil, a power output means for outputting AC power, and a pair of power transmission members for transmitting AC power from the power output means to the heating coil And a variable section that varies at least one of the facing distance, length, width, and facing area of the pair of power transmission members.

  In the present invention, as the second solution, in the first solution, a current sensor that detects an alternating current flowing in the heating coil, and a facing distance and a length of the pair of power transmission members so that the alternating current is maximized. Further, a means of further including a control unit that changes the at least one of the width and the facing area to the variable unit is adopted.

  In the present invention, as a third solving means, in the first or second solving means, the pair of power transmission members is a pair of bus bars arranged opposite to each other and extendable in the length direction. A means of changing the length of the pair of bus bars is adopted.

  In the present invention, as a fourth solving means, in the first or second solving means, the pair of power transmission members is a pair of bus bars arranged opposite to each other and expandable in the width direction. A means of changing the width of the pair of bus bars is employed.

  In the present invention, as a fifth solving means, in the first or second solving means, the pair of power transmission members are a pair of bus bars arranged to face each other, and can slide in opposite directions to each other, The variable portion employs means for varying the facing area by sliding the pair of bus bars in the opposite direction.

  In the present invention, as a sixth solution, in the first or second solution, the pair of power transmission members are a power supply coil and a power reception coil that perform non-contact power supply, and the power supply coil is connected to the power generation means. The power receiving coil is connected to the heating coil, and the variable portion adopts a means for varying the facing distance between the power feeding coil and the power receiving coil.

  According to the present invention, by adjusting at least one of a facing distance, a length, a width, and a facing area of the pair of power transmission members, the impedance on the power feeding side with respect to the heating coil that is the AC power receiving side is adjusted. Is possible. Further, according to the present invention, since the impedance on the power feeding side is adjusted by the pair of power transmission members constituting the AC power transmission path, the apparatus is larger than the case where the impedance on the power feeding side is adjusted by a variable coil or a variable capacitor. An increase in cost due to the conversion can be suppressed.

It is a block diagram which shows the function structure of the induction heating apparatus which concerns on 1st Embodiment of this invention. It is a schematic diagram which shows the detail of the heating part 5 in 1st Embodiment of this invention. It is a side view which shows the state of the 1st, 2nd bus bars 51 and 52 in 1st Embodiment of this invention. It is a side view showing the state of the 1st and 2nd bus bars 51A and 52A in a 2nd embodiment of the present invention. It is a top view which shows the state of the 1st, 2nd bus bars 51B and 52B in 3rd Embodiment of this invention. It is a block diagram which shows the function structure of the induction heating apparatus which concerns on 4th Embodiment of this invention. It is a figure which shows the modification of 1st Embodiment of this invention. It is a figure which shows the modification of embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
[First embodiment]
First, the first embodiment will be described. As shown in FIG. 1, the induction heating apparatus according to the first embodiment includes a converter 1, an inverter 2, a transformer 3, a capacitor 4, and a heating unit 5. Of these components, the converter 1, the inverter 2, the transformer 3, and the capacitor 4 constitute power output means in the first embodiment.

  As shown in FIG. 2, the heating unit 5 includes a first bus bar 51 (power transmission member), a second bus bar 52 (power transmission member), a first power line 53, a second power line 54, and heating. A coil 55, a current sensor 56, a variable unit 57, and a control unit 58 are included. Among these components, the first and second bus bars 51 and 52 are power transmission members in the first embodiment.

  Such an induction heating device is a device that operates by receiving power supply from a system power source such as a three-phase 200V or a three-phase 400V. That is, the converter 1 has an input end connected to the system power supply and an output end connected to the input end of the inverter 2. Such a converter 1 is a rectifier that converts system power supplied from a system power source into DC power, and outputs the DC power to the inverter 2. The inverter 2 converts the DC power supplied from the converter 1 into AC power (high frequency power) having a frequency higher than that of the system power, and a pair of output terminals are connected to the primary winding 31 of the transformer 3. Yes.

  The transformer 3 includes a primary winding 31 and a secondary winding 32, and the primary winding 31 is connected to the output terminal of the inverter 2. Further, as shown in FIG. 2, the secondary winding 32 has one end connected to one end of the capacitor 4 and the other end connected to one end of the second bus bar 52. Such a transformer 3 transforms AC power supplied from the inverter 2 and supplies it to the capacitor 4 and the heating unit 5. One end of the capacitor 4 is connected to one end of the secondary winding 32, and the other end is connected to one end of the first bus bar 51 of the heating unit 5. Such a capacitor 4 is a resonance capacitor that forms a resonance circuit together with the transformer 3, the first and second bus bars 51, 52 and the heating coil 55.

  In the heating unit 5, the first bus bar 51 is a rectangular plate made of a conductor such as copper, and one end in the length direction is connected to the other end of the capacitor 4, and the other end is the first power line 53. Connected to one end. The second bus bar 52 has the same material, size, and shape as the first bus bar 51, one end in the length direction is connected to the other end of the secondary winding 32, and the other end is the second bus bar 52. The power line 54 is connected to one end. The first and second bus bars 51 and 52 are disposed so as to face each other.

  The first power line 53 is a flexible conductor such as a flexible bus bar, and one end is connected to the other end of the first bus bar 51 and the other end is connected to one end of the heating coil 55. Similar to the first power line 53, the second power line 54 is a conductive wire having one end connected to the other end of the second bus bar 52 and the other end connected to the other end of the heating coil 55. Has been.

  The heating coil 55 has one end connected to the other end of the first power line 53 and the other end connected to the other end of the second power line 54. Such a heating coil 55 generates a magnetic field around the energization of the high-frequency power, and induction-heats a steel plate (object to be heated) disposed in the vicinity. The current sensor 56 is attached to the second power line 54 and detects a high-frequency current flowing through the second power line 54 by the high-frequency power, that is, an alternating current flowing from the second bus bar 52 to the heating coil 55, and the detection result Is output to the control unit 58.

  The variable portion 57 changes the facing distance between the first bus bar 51 and the second bus bar 52, that is, moves the first and second bus bars 51, 52 closer to or away from each other, as shown in FIG. Thus, it is comprised from the movable part 57a, the motor driver 57b, and the motor 57c. The movable portion 57a is made of an insulating material and has a female screw portion a1 and b1 in which a female screw groove is formed in a screw hole, and a rod-shaped male screw portion in which a male screw groove that engages with each of the female screw portions a1 and b1 is formed on the peripheral surface. It is a kind of ball screw mechanism composed of a2 and b2.

  One female screw part a1 is fixed to the first bus bar 51, and the other female screw part b1 is fixed to the second bus bar 52. In addition, the male screw portions a <b> 2 and b <b> 2 are arranged so that the axis line coincides with the opposing direction of the first bus bar 51 and the second bus bar 52. When the male screw portions a2 and b2 are rotationally driven by the motor 57c, the movable portion 57a has a first bus bar 51 fixed to each of the female screw portions a1 and b1 as the male screw portions a2 and b2 rotate. And the 2nd bus bar 52 is moved to an opposing direction.

  The motor driver 57b generates a motor drive signal (drive current) for driving the motor 57c based on a command signal input from the control unit 58, and supplies the motor drive signal to the motor 57c. The motor 57c rotates and drives the male screw portions a2 and b2 by rotating based on the motor drive signal supplied from the motor driver 57b.

  The control unit 58 is a microcontroller in which a CPU (Central Processing Unit), a memory, an input / output interface, and the like are integrated, and the high frequency current is maximized based on a current detection signal input from the current sensor 56. The variable unit 57 is feedback-controlled. That is, the control unit 58 causes the variable unit 57 to adjust the facing distance between the first and second bus bars 51 and 52 so that the high-frequency current is maximized.

Next, the operation of the induction heating apparatus configured as described above will be described.
First, an operator starts induction heating by bringing the heating coil 55 of the induction heating apparatus supplied with power from the system power supply close to the steel plate (object to be heated). At this time, the inductance (impedance) of the heating coil 55 changes according to the material of the steel plate, the distance between the heating coil 55 and the steel plate, and the like. In order to efficiently heat the steel sheet by supplying the largest high-frequency power (high-frequency current) to such a heating coil 55, the inductance (impedance) on the power feeding side with respect to the heating coil 55 (high-frequency power receiving side) is heated. It is necessary to match the inductance (impedance) of the coil 55.

  The current sensor 56 outputs the detected value of the high-frequency current flowing through the heating coil 55, that is, the high-frequency current flowing through the second power line 54, to the control unit 58 as a current detection signal. The control unit 58 adjusts the facing distance between the first and second bus bars 51 and 52 by performing feedback control of the variable unit 57 so that the high-frequency current becomes maximum based on the current detection signal. As a result, the impedance (inductance) on the power feeding side with respect to the heating coil 55 (high-frequency power receiving side) is adjusted to match the inductance of the heating coil 55.

  For example, when the inductance of the heating coil 55 is increased, it is necessary to reduce the inductance of the first and second bus bars 51 and 52, so that the opposing distance between the first and second bus bars 51 and 52 is reduced. (Refer to FIG. 3A.) When the inductance of the heating coil 55 becomes small, it is necessary to increase the inductance of the first and second bus bars 51 and 52, so the first and second bus bars 51, The facing distance of 52 becomes wider (see FIG. 3B).

  According to the first embodiment, the feeding-side impedance (inductance) for the heating coil 55 (power receiving side) can be matched by changing the facing distance between the first and second bus bars 51 and 52. Is possible. Further, according to the first embodiment, since the impedance on the power feeding side is adjusted by the first and second bus bars 51 and 52 constituting the transmission path of the high frequency power, the impedance on the power feeding side is adjusted by a variable coil or a variable capacitor. It is possible to suppress an increase in cost associated with an increase in the size of the apparatus as compared with the conventional technique to be adjusted.

[Second Embodiment]
Next, a second embodiment will be described with reference to FIG.
The induction heating apparatus according to the second embodiment includes a movable portion 57d instead of the movable portion 57a of the first embodiment, and is replaced with the first and second bus bars 51 and 52 of the first embodiment. The second bus bars 51A and 52A are provided. Other components are the same as those in the first embodiment.

  The first and second bus bars 51A, 52A in the second embodiment are respectively composed of two rectangular plate members 51a, 51b, 52a, 52b that are slidable in the length direction. That is, the first bus bar 51A is composed of two plate members 51a and 51b, and the second bus bar 52A is composed of two plate members 52a and 52b. The first and second bus bars 51A, 52A change in overall length as the two plate members 51a, 51b, 52a, 52b slide in the length direction.

  Further, in the movable portion 57d in the second embodiment, the axis of the male screw portions a2 and b2 is not the direction in which the first and second bus bars 51A and 52A are opposed, but the length of the first and second bus bars 51A and 52A The direction is set. The female screw portions a1 and b1 in the movable portion 57d are fixed to one of the two plate members 51a, 51b, 52a, and 52b, respectively. Such a movable portion 57d slides one plate member 51a, 52a in the length direction with respect to the other fixed plate member 51b, 52b.

  In such an induction heating device, the overall amount of the first and second bus bars 51A and 52A is changed by varying the sliding amount of the one plate member 51a and 52a so that the high-frequency current flowing through the heating coil 55 is maximized. The long length, that is, the inductance of the first and second bus bars 51A and 52A is adjusted. As a result, the inductance (impedance) on the power feeding side with respect to the heating coil 55 (high-frequency power receiving side) is adjusted to match the inductance of the heating coil 55.

  For example, when the inductance of the heating coil 55 is increased, it is necessary to reduce the inductance of the first and second bus bars 51A and 52A, so that the first and second bus bars 51A and 52A are shortened (FIG. 4). (Refer to (a)) When the inductance of the heating coil 55 becomes small, it is necessary to increase the inductance of the first and second bus bars 51A and 52A, so the first and second bus bars 51A and 52A are long. (See FIG. 4B).

  According to the second embodiment, it is possible to adjust the inductance (impedance) on the power feeding side by changing the lengths of the first and second bus bars 51A and 52A. Further, according to the second embodiment, since the impedance on the power feeding side is adjusted by the first and second bus bars 51A and 52A constituting the transmission path of the high frequency power, the impedance on the power feeding side is adjusted by a variable coil or a variable capacitor. It is possible to suppress an increase in cost associated with an increase in the size of the apparatus as compared with the conventional technique to be adjusted.

[Third Embodiment]
Next, a third embodiment will be described with reference to FIG.
The induction heating apparatus according to the third embodiment includes a movable portion 57e instead of the movable portion 57a of the first embodiment, and the first and second bus bars 51 and 52 of the first embodiment are replaced with the first and second bus bars 51 and 52. Two bus bars 51B and 52B are provided. Other components are the same as those in the first embodiment. FIG. 5 is a top view of the first bus bar 51B, the first power line 53, the female screw part a1, and the male screw part a2, but below that is the second bus bar 52B, the second power line 54, and the female screw part. b1 and the external thread part b2 are arrange | positioned similarly.

  The first and second bus bars 51B and 52B in the third embodiment are respectively composed of two rectangular plate members 51c, 51d, 52c and 52d which are slidable in the width direction. That is, the first bus bar 51B is composed of two plate members 51c and 51d, and the second bus bar 52B is composed of two plate members 52c and 52d. The overall width of the first and second bus bars 51B and 52B changes as the two plate members 51c, 51d, 52c and 52d slide in the width direction.

  In the movable portion 57e in the third embodiment, the female screw portions a1 and b1 are fixed to one of the two plate members 51c, 51d, 52c, and 52d, respectively. Such a movable part 57e slides one plate member 51c, 52c with respect to the other fixed plate member 51d, 52d in the width direction.

  In such an induction heating apparatus, the overall amount of the first and second bus bars 51B and 52B is changed by varying the slide amount of the one plate member 51c and 52c so that the high-frequency current flowing through the heating coil 55 is maximized. Width, that is, the inductance of the first and second bus bars 51B and 52B is adjusted. As a result, the inductance (impedance) on the power feeding side with respect to the heating coil 55 (high-frequency power receiving side) is adjusted to match the inductance of the heating coil 55.

  For example, when the inductance of the heating coil 55 is increased, it is necessary to reduce the inductance of the first and second bus bars 51B and 52B, so the width of the first and second bus bars 51B and 52B is increased ( In the case where the inductance of the heating coil 55 is reduced, it is necessary to reduce the inductance of the first and second bus bars 51B and 52B. Therefore, the first and second bus bars 51B and 52B are required. Becomes narrower (see FIG. 5B).

  According to the third embodiment, the impedance (inductance) on the power feeding side can be adjusted by changing the widths of the first and second bus bars 51B and 52B. Further, according to the third embodiment, since the impedance on the power feeding side is adjusted by the first and second bus bars 51B and 52B constituting the high-frequency power transmission path, the impedance on the power feeding side is adjusted by a variable coil or a variable capacitor. It is possible to suppress an increase in cost associated with an increase in the size of the apparatus as compared with the conventional technique to be adjusted.

[Fourth Embodiment]
Next, a fourth embodiment will be described with reference to FIG.
The induction heating device according to the fourth embodiment includes a converter 11, an inverter 12, a first capacitor 13, a power feeding coil 14, a power receiving coil 15, a second capacitor 16, a heating coil 17, a current sensor 18, a variable unit 19, and a control. The unit 20 is configured. In addition, about the converter 11, the inverter 12, and the heating coil 17, since it is the structure similar to the converter 1, the inverter 2, and the heating coil 55 of 1st-3rd embodiment, description is abbreviate | omitted. Further, the converter 11 and the inverter 12 constitute power output means in the fourth embodiment.

  One end of the first capacitor 13 is connected to one output terminal of the inverter 12, and the other end is connected to one end of the feeding coil 14. Such a first capacitor 13 is a resonance capacitor that forms a resonance circuit with the feeding coil 14. The feeding coil 14 has one end connected to the other end of the first capacitor 13 and the other end connected to the other output end of the inverter 12. Such a feeding coil 14 generates a high-frequency magnetic field when high-frequency power is supplied from the inverter 12.

  The power receiving coil 15 has one end connected to one end of the second capacitor 16 and the other end connected to the other end of the heating coil 17. Such a power receiving coil 15 is electromagnetically coupled to the power feeding coil 14 and generates high frequency power corresponding to the high frequency power supplied to the power feeding coil 14. The power supply coil 14 and the power reception coil 15 perform magnetic resonance type non-contact power supply, and are disposed to face each other. The second capacitor 16 has one end connected to one end of the power receiving coil 15 and the other end connected to one end of the heating coil 17. Such a second capacitor 16 is a resonance capacitor that forms a resonance circuit with the power receiving coil 15 and the heating coil 17.

  The current sensor 18 is provided between the other end of the power receiving coil 15 and the other end of the heating coil 17, detects a high-frequency current flowing from the power receiving coil 15 to the heating coil 17, and controls a current detection signal indicating the detection result. To the unit 20. The variable unit 19 varies the facing distance between the power feeding coil 14 and the power receiving coil 15 based on a control command input from the control unit 20. Such a variable part 19 is comprised from the ball screw mechanism, the motor driver, the motor, etc. similarly to the movable part of 1st-3rd embodiment, for example.

  The control unit 20 is a microcontroller in which a CPU (Central Processing Unit), a memory, an input / output interface, and the like are integrated, and a high-frequency current flowing through the heating coil 17 based on a current detection signal input from the current sensor 18. The variable portion 19 is feedback-controlled so that is maximized. That is, the control unit 20 causes the variable unit 19 to adjust the facing distance between the feeding coil 14 and the receiving coil 15 so that the high-frequency current is maximized.

  In such an induction heating apparatus, the facing distance between the feeding coil 14 and the receiving coil 15 is adjusted so that the high-frequency current flowing through the heating coil 17 is maximized based on the current detection signal of the current sensor 18. As a result, the impedance (inductance) on the power feeding side with respect to the heating coil 17 (high-frequency power receiving side) is adjusted to match the inductance of the heating coil 17.

  According to the fourth embodiment, the impedance (inductance) on the power feeding side can be adjusted by changing the facing distance between the power feeding coil 14 and the power receiving coil 15. Further, according to the fourth embodiment, since the power supply side impedance is adjusted by the power supply coil 14 and the power reception coil 15 constituting the transmission path of the high frequency power, the power supply side impedance is adjusted by a variable coil or a variable capacitor. Compared to the technology, it is possible to suppress an increase in cost due to the increase in size of the apparatus.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) In the first embodiment, the impedance (inductance) on the power feeding side is adjusted by changing the facing distance between the first and second bus bars 51 and 52, but the present invention is not limited to this. For example, as shown in FIG. 7, two rectangular plate members 51e, 51f, 52e, 52f connected in the length direction constitute first and second bus bars 51C, 52C, and two plate members 51e. , 51f, 52e, 52f, only one plate member 51e, 52e may be configured to move in the facing direction.

  For example, when the inductance of the heating coil 55 is increased, it is necessary to reduce the inductance of the first and second bus bars 51C and 52C, so that the opposing distance between the plate members 51e and 52e is reduced (FIG. 7A). )), When the inductance of the heating coil 55 is reduced, it is necessary to increase the inductance of the first and second bus bars 51C and 52C, so that the opposing distance between the plate members 51e and 52e is increased (FIG. 7). (See (b)).

(2) In the first to third embodiments, the facing distance, length, or width of the pair of bus bars arranged to face each other is variable, but the present invention is not limited to this. For example, as shown in FIG. 8, the first and second bus bars 51D and 52D can slide in the opposite directions, and the variable portion 57 slides the first and second bus bars 51D and 52D in the opposite directions. By doing so, the opposing area may be varied.

  For example, when the inductance of the heating coil 55 becomes small, it is necessary to increase the inductance of the first and second bus bars 51D and 52D, so that the opposing area of the first and second bus bars 51 and 52 is small. (See FIG. 8B), when the inductance of the heating coil 55 is increased, it is necessary to reduce the inductance of the first and second bus bars 51D and 52D. The opposing areas of the first and second bus bars 51 and 52 are increased (see FIG. 8A).

(3) In the first to third embodiments and the modified examples (1) and (2), any one of the facing distance, length, width, and facing area of the pair of bus bars arranged to face each other is changed. The distance, length, width, and facing area may be varied at the same time.

(4) In the first embodiment, both the first and second bus bars 51 and 52, and in the fourth embodiment, both the feeding coil 14 and the receiving coil 15 are moved, but one of them is fixed. However, the other may be moved.
(5) In the first to fourth embodiments and the modified examples (1) and (2), the opposing distance, length, width and opposing area of the pair of bus bars or the opposing distance between the feeding coil 14 and the receiving coil 15 are set. Although automatically controlled, the present invention is not limited to this. Instead of the automatic control, the facing distance, length, width, and facing area may be adjusted by manual operation. In this case, the current sensors 56 and 18 and the control units 58 and 20 are not necessary.

(6) Although the capacitor 4 is provided in the first to third embodiments, the capacitor 4 may be omitted. In the fourth embodiment, the first capacitor 13 and the second capacitor 16 are also provided, but the first and second capacitors 13 and 16 may be omitted. In other words, the fourth embodiment is an induction heating device that performs magnetic resonance type non-contact power feeding, but may be an induction heating device that performs electromagnetic induction type non-contact power feeding.

  DESCRIPTION OF SYMBOLS 1 ... Converter, 2 ... Inverter, 3 ... Transformer, 4 ... Condenser, 5 ... Heating part, 31 ... Primary winding, 32 ... Secondary winding, 51, 51A, 51B, 51C, 51D ... 1st bus bar ( (Power transmission member), 52, 52A, 52B, 52C, 52D ... second bus bar (power transmission member), 53 ... first power line, 54 ... second power line, 55 ... heating coil, 56 ... current sensor, 57 ... variable part, 57a, 57d, 57e ... movable part, 57b ... motor driver, 57c ... motor, a1, b1 ... female screw part, a2, b2 ... male screw part, 58 ... control part, 11 ... converter, 12 ... inverter, 13 DESCRIPTION OF SYMBOLS 1st capacitor | condenser, 14 ... Feed coil, 15 ... Power receiving coil, 16 ... 2nd capacitor | condenser, 17 ... Heating coil, 18 ... Current sensor, 19 ... Variable part, 20 ... Control part, 51a, 51b, 1c, 51d, 51e, 51f, 52a, 52b, 52e, 52f ... plate member

Claims (6)

A heating coil;
Power output means for outputting AC power;
A pair of power transmission members for transmitting the AC power from the power output means to the heating coil;
An induction heating apparatus comprising: a variable portion that varies at least one of a facing distance, a length, a width, and a facing area of the pair of power transmission members. A current sensor for detecting an alternating current flowing in the heating coil;
The apparatus further comprises: a control unit configured to change at least one of a facing distance, a length, a width, and a facing area of the pair of power transmission members to a variable unit so that the alternating current is maximized. 2. The induction heating apparatus according to 1. The pair of power transmission members are a pair of bus bars that are arranged opposite to each other and extendable in the length direction,
The induction heating apparatus according to claim 1, wherein the variable portion varies a length of the pair of bus bars. The pair of power transmission members are a pair of bus bars that are arranged opposite to each other and extendable in the width direction,
The induction heating apparatus according to claim 1, wherein the variable portion varies a width of the pair of bus bars. The pair of power transmission members are a pair of bus bars arranged to face each other, and can slide in opposite directions to each other,
The induction heating apparatus according to claim 1, wherein the variable portion varies the facing area by sliding the pair of bus bars in the reverse direction. The pair of power transmission members are a power feeding coil and a power receiving coil that perform non-contact power feeding, the power feeding coil is connected to power generating means, and the power receiving coil is connected to the heating coil,
The induction heating apparatus according to claim 1, wherein the variable portion varies a facing distance between the power feeding coil and the power receiving coil.

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