JP5361757B2 - Induction heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive induction heating device capable of performing reduction of power loss and restraint of a calorific value on a switching element of a common arm and attaining compactness, lightweightness, and high reliability. <P>SOLUTION: The induction heating device includes a plurality of full bridge type inverter circuits formed with the common arm and a plurality of exclusive arms, heating coils and resonant capacitors respectively connected in series between the common arm and the exclusive arms, a plurality of drive circuits for supplying drive signals to respective switching elements of respective arms, and a control circuit for controlling current flowing in the heating coil by controlling a phase difference of the drive signals supplied to the exclusive arms by delaying rather than the drive signal supplied to the common arm or the length of a period for supplying the drive signals to the exclusive arms. The switching element of the common arm is formed with a wideband gap semiconductor element, and the switching elements of the exclusive arms are formed with silicon semiconductor elements. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an induction heating device, and more particularly to a power supply device for an induction heating device.

  In a conventional induction heating apparatus, a full-bridge inverter circuit is used to supply a high-frequency current to a heating coil. The inverter circuit includes two sets of arms in which two switching elements are connected in series, It has a heating coil and a resonance capacitor connected in series to the intermediate contact of each arm. For example, in Patent Documents 1 and 2, two sets of heating coils and resonant capacitors are connected in series between one shared arm and two non-shared arms in order to prevent interference sound (beating phenomenon). A full-bridge inverter circuit that supplies a high-frequency current individually to the heating coil has also been proposed.

  In addition, the power supply device of the induction heating device described in Patent Document 3 supplies a high-frequency current to a single heating coil using a full-bridge inverter circuit having two sets of arms composed of two switching elements. In order to reduce the power loss due to the switching elements and to suppress the amount of heat generated (and thus to reduce the size of the cooling device etc.), it is described that all four switching elements are composed of wide band gap semiconductor devices. .

JP-A-9-185986 (paragraphs 19 to 22) Japanese Patent No. 3687028 (paragraphs 15 to 26) JP 2006-331965 A (Claim 8)

  The full-bridge inverter circuit in the induction heating apparatus described in Patent Documents 1 and 2 includes an arm in which two switching elements having the same specifications are connected in series, and supplies a high-frequency current to a plurality of heating coils by sharing the common arm. Therefore, the effective current value flowing through the switching element of the common arm is larger than that of other switching elements. As a result, since the power loss of the switching element of the common arm is large (a large amount of heat is generated), there is a risk that the risk to the operation reliability is increased.

  On the other hand, according to the induction heating device described in Patent Document 3, since all the switching elements constituting the full-bridge inverter circuit are constituted by wide band gap semiconductor devices that are more expensive than general and inexpensive silicon devices, There was a problem that the manufacturing cost of the entire induction heating apparatus increased significantly.

  Therefore, the present invention has been made in view of the above problems, and by reducing power loss and suppressing heat generation in the switching element of the shared arm, the reliability of the power supply device including the switching element of the shared arm is improved. To realize a cheaper induction heating device that can improve and reduce the size, weight, and cost of peripheral devices of power supply devices such as radiating fins and cooling fans for cooling the switching elements of the shared arm It is aimed.

An induction heating device according to the present invention is an induction heating device including a heating port on which a heated object is placed, and is configured by a shared arm and a plurality of dedicated arms each having a plurality of switching elements connected in series. A plurality of full bridge inverter circuits, a plurality of heating coils and resonant capacitors connected in series between each of the shared arm and the plurality of dedicated arms, and each of the shared arm and the plurality of dedicated arms. A plurality of drive circuits for supplying a drive signal to the switching element; and a phase difference between the drive signals supplied to the plurality of dedicated arms with a delay from the drive signal supplied to the shared arm. A control circuit for controlling the current flowing through the heating coil, and the plurality of switching elements of the common arm are wide. Is constructed using a band gap semiconductor element, a plurality of switching elements of the plurality of dedicated arm is constituted by using a silicon semiconductor device, the plurality of heating coils are disposed immediately below the single the heating port, said plurality The heating coil is a central heating coil disposed in the center immediately below the single heating port, and a plurality of arc coils that are arranged adjacent to the periphery of the central heating coil and have an arc shape along the central heating coil. And a peripheral heating coil .

  According to the present invention, since it is possible to reduce the power loss and the amount of heat generated in the switching element of the shared arm, it is possible to reduce the size and weight of the radiating fin and the cooling fan for cooling the switching element of the shared arm. Unprecedented remarkable effects such as low cost and high reliability with respect to temperature can be obtained.

It is a schematic perspective view which shows the whole induction heating apparatus 1 which concerns on this invention. 1 is a block circuit diagram of a high frequency power supply according to Embodiment 1. FIG. 3 is a timing chart of drive signals output to switching elements of each full-bridge inverter circuit according to Embodiment 1 (phase difference control, when the phase difference is 0 °). FIG. 4 is a timing chart of drive signals output to switching elements of each full-bridge inverter circuit similar to FIG. 3 (when the phase difference is the same instead of 0 °). It is a timing chart of the drive signal output to the switching element of each full bridge type inverter circuit similar to FIG. 3 (when the phase difference is different from 0 °). It is a timing chart of the drive signal output to the switching element of each full bridge type inverter circuit concerning Embodiment 2 (time division control). FIG. 5 is a block circuit diagram of a high frequency power supply according to a third embodiment. 10 is a timing chart of drive signals output to switching elements of each full-bridge inverter circuit according to Embodiment 3 (phase difference control). 6 is a plan view of a heating coil according to Embodiment 4. FIG. Modification 1 of the heating coil which concerns on Embodiment 4 is shown. Modification 2 of the heating coil which concerns on Embodiment 4 is shown. Modification 3 of the heating coil according to Embodiment 4 is shown. Modification 4 of the heating coil which concerns on Embodiment 4 is shown.

  Embodiments of an induction heating apparatus according to the present invention will be described below with reference to the accompanying drawings. In the description of each embodiment, terms indicating directions (for example, “upward direction” and “downward direction”) are used as appropriate in order to facilitate understanding. Is not intended to limit the present invention.

Embodiment 1 FIG.
The first embodiment of the induction heating apparatus according to the present invention will be described in detail below with reference to FIGS. FIG. 1 is a schematic perspective view showing an entire induction heating apparatus 1 according to the present invention. In FIG. 1, an induction heating cooker 1 generally includes a casing 3, a top plate 4 formed of glass or the like covering substantially the entire upper surface thereof, and first and second IH heating units arranged on the left and right sides. Parts 10, 20, a radiant heating part 5, and a grill heating part 6. Although not shown in detail here, each of the IH heating units 10 and 20 includes electromagnetic induction heating coils (hereinafter simply referred to as “heating coils”) 11 and 21 that are spirally formed in a predetermined plane. When a high-frequency current is supplied from a high-frequency power source 2 to be described later, an eddy current is formed in a pan that is a heated object made of a metal material placed on the top plate 4, and the pan is induction-heated by the Joule heat.

  The induction heating device 1 also displays the heating power adjustment dials 7a and 7b used by the user to operate the heating power of the IH heating units 10 and 20, the radiant heating unit 5 and the grill heating unit 6, and the control states thereof. Liquid crystal display unit 8 and an intake window 9 a and an exhaust window 9 b provided behind the housing 3.

  FIG. 2 is a block circuit diagram of the high-frequency power supply 2 (power supply device) according to the first embodiment. As shown schematically in FIG. 2, the high-frequency power supply 2 of Embodiment 1 includes a single-phase or three-phase commercial AC power supply 110, a rectifier circuit 112 that full-wave rectifies the AC voltage of the commercial AC power supply 110, and a rectifier circuit The smoothing capacitor 116 for smoothing the DC voltage of full-wave rectification obtained at 112, and the first and second for supplying high-frequency current to the heating coils 11, 21 of the first and second IH heating units 10, 20 2 full-bridge inverter circuits 12 and 22 (shown by broken lines in FIG. 2).

One full-bridge inverter circuit 12 includes a shared arm 100 in which a high-voltage side switching element 104a and a low-voltage side switching element 104b are connected in series, and a first high-voltage side switching element 14a and a low-voltage side switching element 14b connected in series. The first non-shared arm 15 is composed of a first heating coil 11 and a first resonant capacitor 13 that electrically connect the intermediate contacts of the shared arm 100 and the first non-shared arm 15. ing. Hereinafter, for convenience of explanation, the non-shared arm is referred to as a “dedicated arm” for convenience.
That is, the first full-bridge inverter circuit 12 includes a shared arm 100, a first dedicated arm 15, and a first heating coil 11 (and a first resonant capacitor 13) connected in series therebetween. It is composed of

Similarly, the other full-bridge inverter circuit 22 includes the shared arm 100, the second dedicated arm 25 in which the second high-voltage side switching element 24a and the low-voltage side switching element 24b are connected in series, the shared arm 100, and the second The second heating coil 21 and the second resonance capacitor 23 are electrically connected between the intermediate contacts of the two dedicated arms 25.
That is, the second full-bridge inverter circuit 22 includes the shared arm 100, the second dedicated arm 25, and the second heating coil 21 (and the second resonant capacitor 23) connected in series between them. It is composed of

  Needless to say, the heating coils 11 and 21 and the resonance capacitors 13 and 23 may be connected in series between the shared arm 100 and the first and second dedicated arms 15 and 25, and each other. The positions may be replaced.

  As described above, the full-bridge inverter circuits 12 and 22 are configured so that the shared arm 100 and the first and second dedicated arms 15 and 25 cooperate to generate a high-frequency current in the first and second heating coils 11 and 21. The high-frequency current supplied to both the first and second heating coils 11 and 21 flows through the switching elements 104a and 104b of the shared arm 100.

The high frequency power supply 2 according to the first embodiment includes a drive circuit 106 that outputs a drive signal for switching control of the switching elements 104a and 104b of the shared arm 100. The high-frequency power source 2 includes a first drive circuit 16 that outputs a drive signal for switching control of the first switching elements 14 a and 14 b of the first dedicated arm 15, and a second drive of the second dedicated arm 25. And a second drive circuit 26 that outputs a drive signal for switching control of the switching elements 24a and 24b. Similarly, for easy understanding, the drive circuit 106 for driving the shared arm 100 is referred to as a “shared drive circuit”, and the drive circuits 16 and 26 for driving the dedicated arms 15 and 25 are referred to as “dedicated drive”. Circuit ".
Further, the high frequency power supply 2 includes a control circuit 108 that outputs a control signal for controlling the shared drive circuit 106 and the first and second dedicated drive circuits 16 and 26.

By the way, it is known that a wide band gap semiconductor generally has high voltage resistance, high allowable current density resistance, high heat resistance, and low power loss.
Therefore, according to the high frequency power supply 2 according to the present invention, the switching elements 104a and 104b of the shared arm 100 have larger current effective values than the switching elements 14 and 24 of the other dedicated arms 15 and 25. The wide band gap semiconductor made of silicon, gallium nitride-based material or diamond is used, and the switching elements 14 and 24 of the dedicated arms 15 and 25 having a smaller current effective value are made of a cheaper silicon semiconductor. . As a result, the reliability of the switching element 104 of the shared arm 100 that controls switching of a large current flowing through both the heating coils 11 and 21 is ensured, and the switching element 14 of the dedicated arms 15 and 25 having a relatively small effective current value. , 24 can be manufactured with a cheaper one and manufacturing cost can be reduced. Here, for convenience of explanation, the switching element 104 constituting the shared arm 100 is referred to as a “WB (abbreviation of wide band gap) switching element”, and the switching elements 14 and 24 of the dedicated arms 15 and 25 are connected to the band gap by the WB switching element. Is small, it is referred to as an “NB (narrow band gap) switching element”.

Next, with reference to FIGS. 3 to 5, the operation of the high frequency power supply 2 of the induction heating apparatus according to Embodiment 1 will be described.
When the user adjusts the heating power adjustment dials 7a and 7b to adjust the heating power of the pan, in the block circuit diagram of FIG. 2, the control circuit 108 controls the shared drive circuit 106 and the first and second dedicated drive circuits 16 and 26. Then, control signals corresponding to the heating power adjustment dials 7a and 7b are output, and these drive circuits 106, 16 and 26 output corresponding drive signals to the WB switching element 104 and the NB switching elements 14 and 24, respectively. The switching elements 104, 14, and 24 perform switching operations (turns on and off) based on drive signals from the drive circuits 106, 16, and 26, respectively.

3 to 5 are output to the WB switching elements 104a and 104b of the shared arm 100 and the NB switching elements 14a, 14b, 24a, and 24b of the dedicated arms 15 and 25 in the high-frequency power source 2 of the first embodiment. It is a timing chart of a drive signal. In FIG. 3, the phase difference between the drive signals output to the WB switching element 104a and the NB switching elements 14a and 24a and the WB switching element 104b and the NB switching elements 14b and 24b is 0 °. No current flows through 21. As shown in FIG. 4, the drive signals output to the NB switching elements 14 and 24 are delayed by a predetermined time (ie, phase differences α ₁ and α ₂ ) with respect to the drive signal output to the WB switching element 104. The high frequency current corresponding to a predetermined delay time flows through the heating coils 11 and 21. The phase difference can be controlled between 0 ° and 180 °, and the current flowing through the heating coils 11 and 21 can be increased as the phase difference increases.

For example, the first heating coil 11 of the IH heating unit 10 disposed on the left side of FIG. 1 is driven by a full bridge inverter circuit 12 including a shared arm 100 and a dedicated arm 15, and the WB switching element 104 and NB switching are driven. By adjusting the phase difference α ₁ between the drive signals output to the element 14, the effective value of the high-frequency current flowing in the first heating coil 11 is controlled, and Joule heat generated in the heated object such as a pan. (I.e. "firepower" for the pan) can be adjusted. This is called “phase difference control” of a full-bridge inverter circuit.

  When the first and second heating coils 11 and 21 are used at the same time, as described above, since the two full-bridge inverter circuits 12 and 22 share the common arm 100, the current effective of the WB switching element 104 is effective. The value will inevitably increase. However, as described above, the WB switching element 104 of the shared arm 100 according to the present invention is formed using a wide band gap semiconductor made of silicon carbide, a gallium nitride material, or diamond, and the NB switching element of the dedicated arms 15 and 25. 14 and 24 are configured using cheaper silicon semiconductors, so that the power loss in the shared arm 100 is reduced (the amount of generated heat is suppressed), and peripheral devices for cooling the WB switching element 104 (radiation fins, The cooling fan and the like can be reduced in size, weight, and cost, and the high-frequency power source 2 can be manufactured at low cost.

In FIG. 4, the drive signal output to the NB switching elements 14 and 24 of the dedicated arms 15 and 25 has the same phase difference (α _{1) with} respect to the drive signal output to the WB switching element 104 of the shared arm 100. = Α ₂ ), the first and second heating coils 11 and 21 are output by outputting with different phase differences (α ₁ ≠ α ₂ ) as shown in FIG. The heating power of the pan heated by can be adjusted independently.

Embodiment 2. FIG.
A second embodiment of the induction heating device 1 according to the present invention will be described in detail below with reference to FIG. The high-frequency power source 2 of the first embodiment adjusts the heating power of the pot by adjusting the phase difference between the drive signals output to the WB switching element 104 and the NB switching elements 14 and 24. The high-frequency power source 2 has the same configuration as that of the induction heating device 1 according to the first embodiment except that the heating power of the pan is adjusted by performing so-called time-sharing control. .

FIG. 6 is a timing chart of drive signals output to the WB switching elements 104a and 104b of the shared arm 100 and the NB switching elements 14a, 14b, 24a, and 24b of the dedicated arms 15 and 25 in the high-frequency power source 2 of the second embodiment. It is.
As shown in FIG. 6, the WB switching elements 104 of the shared arm 100 continuously and alternately perform switching operations (turn on and off). On the other hand, the NB switching element 14 of the first dedicated arm 15 is switched (ON / OFF) in the period A and the period C, and the NB switching element 14 of the second dedicated arm 25 is switched (ON / OFF) only in the period B. During the switching operation of the first and second dedicated arms 15 and 25, the WB switching element 104a of the shared arm 100 and the NB switching elements 14b and 24b of the first and second dedicated arms 15 and 25 are synchronized, and the shared arm When the 100 WB switching elements 104b and the NB switching elements 14a and 24a of the first and second dedicated arms 15 and 25 are synchronized, a predetermined high-frequency current flows through the first and second heating coils 11 and 21. . That is, according to the high-frequency power supply 2 of the second embodiment, the length of the period during which the NB switching elements 14 and 24 of the first and second dedicated arms 15 and 25 are switching (on-off period), that is, Controlling the heating power for each pan placed on each IH heating unit 10, 20 by appropriately selecting the length of the period during which high-frequency current is supplied to the first and second heating coils 11, 21 It is. This is called “time division control” of the full-bridge inverter circuit.

In FIG. 6, the NB switching elements 14 and 24 of the first and second dedicated arms 15 and 25 have a period maintained in an off state, but the WB switching element 104 of the shared arm 100 is always switched, Since the high-frequency current is supplied to both the first and second heating coils 11 and 21, the effective current value is substantially larger than that of the NB switching elements 14 and 24.
However, as described above, the WB switching element 104 of the shared arm 100 according to the present invention is formed using a wide band gap semiconductor, and the NB switching elements 14 and 24 of the dedicated arms 15 and 25 are made of a cheaper silicon semiconductor. Since it is configured, the power loss in the shared arm 100 is reduced (the amount of heat generated is suppressed), and the peripheral devices (such as heat radiation fins and cooling fans) for cooling the WB switching element 104 are reduced in size, weight, and low. In addition to realizing cost reduction, the high-frequency power source 2 can be manufactured at low cost.

Embodiment 3 FIG.
A third embodiment of the induction heating device 1 according to the present invention will be described in detail below with reference to FIGS. The high-frequency power source 2 of the first embodiment supplies high-frequency current to the two IH heating units 10 and 20, but the high-frequency power source 2 of the third embodiment supplies the three IH heating units 10, 20, and 30 with a high frequency current. Since it has the same configuration as that of the induction heating device 1 of Embodiment 1 except that the current is supplied, the description of the overlapping points is omitted.

The induction heating device 1 shown in FIG. 1 has the IH heating units 10 and 20 and the radiant heating unit 5, but the induction heating device 1 according to the third embodiment is arranged at the arrangement position of the radiant heating unit 5. Instead of this, a third IH heating unit 30 is provided.
FIG. 7 is a block circuit diagram of the high-frequency power source 2 according to the third embodiment. The high-frequency power source 2 of the third embodiment has a third full-bridge inverter circuit 32, which has a third dedicated arm 35 and a third heating coil 31 connected in series between the third dedicated arm 35 and the common arm 100. (And the third resonance capacitor 33). The high frequency power supply 2 according to the third embodiment includes a third dedicated drive circuit 36 that outputs a drive signal for switching control of the NB switching elements 34a and 34b of the third dedicated arm 35. Control is performed by the control circuit 108 in the same manner as the first embodiment.

FIG. 8 is a timing chart of drive signals output to the WB switching element 104 of the shared arm 100 and the NB switching elements 14, 24, and 34 of the dedicated arms 15, 25, and 35 in the high-frequency power source 2 according to the third embodiment. . As shown in FIG. 8, with respect to the drive signal output to the WB switching element 104, the drive signal output to the NB switching elements 14, 24, 34 is a predetermined time (that is, phase differences α ₁ , α ₂ , α _3). ), The high-frequency current corresponding to the predetermined delay time flows through the heating coils 11, 21, 31. The phase difference can be controlled between 0 ° and 180 °, and the current flowing through the heating coils 11, 21, 31 can be increased as the phase difference increases. Thus, by adjusting the phase differences α ₁ , α ₂ , α ₃ between the drive signal output to the WB switching element 104 and the NB switching elements 14, 24, 34, the current flows to the heating coils 11, 21, 34. By controlling the effective current value of the high-frequency current, it is possible to adjust Joule heat (that is, “heating power” for the pan) generated in a heated object such as a pan placed above these.

When the three heating coils 11, 21, 31 are used simultaneously, since the three full-bridge inverter circuits 12, 22, 32 share the common arm 100, the effective current value of the WB switching element 104 is substantially growing.
However, as described above, the WB switching element 104 of the shared arm 100 according to the present invention is formed using a wide band gap semiconductor, and the NB switching elements 14, 24, 34 of the dedicated arms 15, 25, 35 are cheaper. Since it is configured using a silicon semiconductor, power loss in the shared arm 100 is reduced (a heat generation amount is suppressed), and a peripheral device (such as a heat radiating fin or a cooling fan) for cooling the WB switching element 104 is downsized. In addition to realizing weight reduction and cost reduction, the high-frequency power source 2 can be manufactured at low cost.

  Although the high frequency power supply 2 of the third embodiment has been described above as performing phase difference control similar to that of the first embodiment, time division control may be performed similarly to the second embodiment.

Embodiment 4 FIG.
The fourth embodiment of the induction heating device 1 according to the present invention will be described in detail below with reference to FIG. Although the IH heating units 10, 20, and 30 according to the first to third embodiments have single heating coils 11, 21, and 31, respectively, in the fourth embodiment, the heating coil 40 is in the radial direction. The inner coil portion 42 and the outer coil portion 44 are divided into two by using two full-bridge inverter circuits 12 and 22 in which the high-frequency power source 2 shares the common arm 100. Since the configuration is the same as that of the induction heating apparatus 1 according to the first embodiment except that the high-frequency current is supplied to the first and second embodiments, the description of the overlapping points is omitted.

  As shown in the plan view of FIG. 9, the heating coil 40 according to the fourth embodiment is formed in a spiral shape in a predetermined plane and is divided into two in the radial direction, a small-diameter inner coil portion 42 and a large-diameter outer coil. Part 44. The inner coil portion 42 and the outer coil portion 44 are independent from each other and are driven by separate (first and second) full-bridge inverter circuits 12 and 22.

Although not particularly shown, the block circuit diagram of the high-frequency power source 2 according to the fourth embodiment is the same as that shown in FIG. 2, and the first and second heating coils 11 and 21 in FIG. These are equivalent to those replaced with the inner coil portion 42 and the outer coil portion 44 according to the above.
Moreover, the heating coil 40 divided into two in the radial direction may be disposed in at least one or both of the left and right IH heating units 10 and 20 shown in FIG. (The one arranged in the center) can also be configured as an IH heating unit having the heating coil 40 divided in the radial direction.

Thus, the first and second full-bridge inverter circuits 12 and 22 supply a high-frequency current to the inner coil portion 42 and the outer coil portion 44 that are divided in the radial direction, and the control circuit 108 supplies the WB switching element 104 to the WB switching element 104. By adjusting the phase difference (α ₁ , α ₂ ) between the output drive signal and the NB switching elements 14 and 24 (phase difference control), the amount of heat generated in the inner and outer regions of the pan is individually adjusted. be able to. For example, when the size (diameter) of the pan is small, the energy conversion efficiency can be improved without consuming wasteful power by stopping the supply of the high-frequency current to the outer coil portion 44.

  Alternatively, as in the second embodiment, the NB switching elements 14 and 24 of the first dedicated arm 15 for the inner coil portion 42 and the second dedicated arm 25 for the outer coil portion 44 are turned on / off. The heating power of the pan may be adjusted by appropriately selecting the length of the running period (that is, the length of the period during which high-frequency current is supplied to the inner coil portion 42 and the outer coil portion 44) (time division control).

When the inner coil portion 42 and the outer coil portion 44 are used at the same time, since the two full-bridge inverter circuits 12 and 22 share the common arm 100, the effective current value of the WB switching element 104 is substantially increased. .
However, the WB switching element 104 of the shared arm 100 according to the present invention is formed using a wide band gap semiconductor, and the NB switching elements 14 and 24 of the dedicated arms 15 and 25 are configured using a relatively inexpensive silicon semiconductor. Therefore, the power loss in the shared arm 100 is reduced (the amount of heat generated is suppressed), and the peripheral devices (such as heat radiation fins and cooling fans) for cooling the WB switching element 104 are reduced in size, weight, and cost. As a result, the high-frequency power source 2 can be manufactured at a lower cost.

  The heating coil 40 according to the fourth embodiment has the inner coil portion 42 and the outer coil portion 44 that are divided into two in the radial direction. However, the present invention is not limited to this. The thing (multicoil) which has the above coil parts may be sufficient.

Modification 1
FIG. 10 shows a first modification of the induction heating device 1 according to the fourth embodiment. The heating coil 50 has a central coil portion 52 and a semicircular arc shape (banana shape or pepper shape) 2 arranged around the central coil portion 52. It has two peripheral coil parts 54a and 54b, and is composed of three coil parts 52, 54a and 54b which are independent from each other.

  Although not shown in detail, the high-frequency power source 2 according to Modification 1 includes first to third full-bridge inverter circuits 12, 22a, and 22b sharing the common arm 100, and includes a central coil portion 52 and a peripheral coil portion 54a. , 54b are independently supplied with a high-frequency current.

  Further, the control circuit 108 adjusts the phase difference (α) between the drive signal output to the WB switching element 104 and the NB switching elements 14 and 24 (phase difference control), or each of the coil units 52, 54a, By appropriately selecting the length of the period during which the high-frequency current is supplied to 54b (time division control), the heating power of the pan is adjusted. For example, when the placing position of the pan is shifted to the right and placed on the top plate 4, by stopping the supply of high-frequency current to the peripheral coil portion 54 b on the left side, wasteful power is not consumed. The energy conversion efficiency can be improved.

Modification 2
FIG. 11 shows a second modification of the induction heating apparatus 1 according to the fourth embodiment. The heating coil 60 has a central coil portion 62 and four semicircular arc-shaped peripheral coil portions 64a to 64d arranged around the central coil portion 62. And includes five coil portions 62 and 64a to 64d that are independent of each other.

Although not shown in detail, the high-frequency power source 2 according to Modification 2 includes first to fifth full-bridge inverter circuits 12 and 22a to 22d sharing the common arm 100, and includes a central coil unit 62 and a peripheral coil unit 64a. High frequency current is supplied independently to ˜64d.
Alternatively, the four peripheral coil portions 64a to 64d may be all connected in series and driven by a single full bridge inverter circuit 22, or the peripheral coil portions 64a, 64b and Peripheral coil portions 64c and 64d may be connected in series, and may be configured to be driven by two full bridge inverter circuits 22a and 22b.

  In addition, the control circuit 108 adjusts the phase difference (α) between the drive signal output to the WB switching element 104 and the NB switching elements 14 and 24 (phase difference control), or each of the coil units 62 and 64a˜. By appropriately selecting the length of the period during which the high-frequency current is supplied to 64d (time-sharing control), when the pan is placed out of position, only the coil portions 64a to 64d in the desired region are driven to convert the energy. Can be improved.

Modification 3
FIG. 12 shows a third modification of the induction heating device 1 according to the fourth embodiment. The heating coil 70 has a central coil portion 72 and six semicircular arc-shaped peripheral coil portions 74a to 74f arranged in the periphery thereof. And is composed of seven coil portions 72 and 74a to 74f that are independent of each other.
Although not shown in detail, the high-frequency power source 2 according to Modification 3 includes first to seventh full-bridge inverter circuits 12 and 22a to 22f sharing the common arm 100, and includes a central coil portion 72 and a peripheral coil portion 74a. High frequency current is supplied to -74f independently.
Further, the control circuit 108 adjusts the phase difference (α) between the drive signal output to the WB switching element 104 and the NB switching elements 14 and 24 (phase difference control), or each of the coil units 72 and 74a˜. By appropriately selecting the length of the period during which the high-frequency current is supplied to 74f (time division control), only the coil portions 74a to 74f in the desired region are driven when the pan is placed out of position and energy conversion efficiency is achieved. Can be improved.

Modification 4
Similarly, FIG. 13 shows a fourth modification of the induction heating device 1 according to the fourth embodiment, and the heating coil 80 includes a central coil portion 82 and eight peripheral coil portions 84a to 84h disposed in the periphery thereof. It has nine coil portions 82 and 84a to 84h that are independent from each other.
Although not shown in detail, the high-frequency power source 2 according to Modification 4 includes first to tenth full-bridge inverter circuits 12 and 22a to 22h sharing the common arm 100, and includes a central coil portion 82 and a peripheral coil portion 84a. A high frequency current is supplied independently to ˜84h.
In addition, the control circuit 108 adjusts the phase difference (α) between the drive signal output to the WB switching element 104 and the NB switching elements 14 and 24 (phase difference control), or each of the coil units 82 and 84a˜. By appropriately selecting the length of the period during which the high-frequency current is supplied to 84h (time-division control), when the pan is placed out of position, only the coil portions 84a to 84h in the desired region are driven and energy conversion efficiency is achieved. Can be improved.

  As described above, in both cases of phase difference control and time-division control, when using a plurality of coil units simultaneously, the effective current value of the WB switching element 104 of the shared arm 100 is the NB switching element 14, It becomes substantially larger than 24. However, the WB switching element 104 of the shared arm 100 according to the present invention is formed using a wide band gap semiconductor, and the NB switching elements 14 and 24 of the dedicated arms 15 and 25 are configured using a relatively inexpensive silicon semiconductor. Therefore, the power loss in the shared arm 100 is reduced (the amount of heat generated is suppressed), and the peripheral devices (such as heat radiation fins and cooling fans) for cooling the WB switching element 104 are reduced in size, weight, and cost. As a result, the high-frequency power source 2 can be manufactured at a low cost.

1: induction heating device, 2: high frequency power supply, 3: housing, 4: top plate, 5: radiant heating unit, 6: grill heating unit, 7: heating power adjustment dial, 8: liquid crystal display unit, 9a: intake window, 9b: exhaust window,
10, 20, 30: IH heating section, 11, 21, 33: heating coil, 12, 22, 32: full bridge inverter circuit, 13, 23, 33: resonance capacitor, 14, 24, 34: NB switching element, 15, 25, 35: dedicated arm, 16, 26, 36: dedicated drive circuit,
40, 50, 60, 70, 80: heating coil, 42: inner coil part, 44: outer coil part, 52, 62, 72, 82: central coil part, 54, 64, 74, 84: peripheral coil part,
100: shared arm, 104: WB switching element, 106: shared drive circuit, 108: control circuit, 110: commercial AC power supply, 112: rectifier circuit, 116: smoothing capacitor.

Claims (3)

In an induction heating apparatus provided with a heating port on which an object to be heated is placed,
A plurality of full-bridge inverter circuits each composed of a shared arm and a plurality of dedicated arms each having a plurality of switching elements connected in series;
A plurality of heating coils and resonant capacitors connected in series between the shared arm and each of the plurality of dedicated arms;
A plurality of drive circuits for supplying drive signals to the switching elements of each of the shared arm and the plurality of dedicated arms;
A control circuit for controlling the current flowing in the plurality of heating coils by controlling the phase difference of the drive signals supplied to the plurality of dedicated arms with a delay from the drive signal supplied to the common arm;
A plurality of switching elements of the shared arm are configured using wide band gap semiconductor elements, and a plurality of switching elements of the plurality of dedicated arms are configured using silicon semiconductor elements,
The plurality of heating coils are arranged directly below the single heating port ,
The plurality of heating coils are:
A central heating coil disposed in the center directly below the single heating port;
An induction heating apparatus comprising: a plurality of peripheral heating coils arranged adjacent to the periphery of the central heating coil and having an arc shape along the central heating coil . The induction heating apparatus according to claim 1, wherein the control circuit controls the phase differences of the drive signals supplied to the plurality of dedicated arms so as to be substantially the same phase difference. The induction heating apparatus according to claim 1 or 2 , wherein the wide band gap semiconductor is formed of silicon carbide, a gallium nitride-based material, or diamond.

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