JP2012099338A - Induction heating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an induction heating apparatus capable of deliciously cooking an omelet, a stir-fried food or the like by controlling electric energy supplied to a peripheral coil to be larger than that supplied to a central coil in a preheating mode to thereby reduce deviation in temperature from a bottom of a pan to a surface thereof.SOLUTION: The induction heating apparatus includes: a central coil; a peripheral coil wound around a periphery of the central coil; a central coil power supply circuit and a peripheral coil power supply circuit for supplying electric power to the central coil and the peripheral coil, respectively; a control circuit for controlling the central coil power supply circuit and the peripheral coil power supply circuit; and a mode selection switch that can select a preheating mode. The control circuit controls the central coil power supply circuit and the peripheral coil power supply circuit so that a high frequency current flows in the same direction in an area where the central coil and the peripheral coil are adjacent to each other, and so that the electric energy supplied to the central coil becomes less than that supplied to the peripheral coil in the preheating mode.

Description

  The present invention relates to an induction heating device, and more particularly to an induction heating device that improves cooking performance by uniformly preheating a heated object.

  In general, when food (water, etc.) contained in a heated object (such as a pan) is boiled and cooked by boiling, etc., bubbles are generated, and when the bubbles are blown, the splashes of the ingredients are scattered, May get dirty around. Therefore, for example, according to the conventional induction heating device described in Patent Document 1, a heating coil composed of an inner coil and an outer coil arranged concentrically is arranged, and high frequency power is supplied to the inner coil and the outer coil. It has been proposed to prevent the splashing of foodstuffs from being scattered by switching the supply alternately and controlling the input power supplied to the outer coil to be smaller than the input power supplied to the inner coil.

  Moreover, according to the induction heating apparatus described in Patent Document 2, the first heating coil disposed below the central portion of the plate, and the ring-shaped second heating coil disposed on the outer periphery of the first heating coil; The high frequency current is alternately supplied to the first heating coil and the second heating coil at a cycle of approximately 30 seconds or less during preheating, and when the plate temperature is equal to or lower than a predetermined temperature, The output time of the high frequency power to the first heating coil is made longer than the output time of the high frequency power, and when the temperature of the plate is equal to or higher than the predetermined temperature, the output time of the high frequency power to the first heating coil is compared with the output time of the high frequency power. It has been proposed to increase the output time of the high-frequency power to the second heating coil within about twice, thereby improving the temperature distribution of the plate so that uneven baking is less likely to occur.

JP 2008-287923 A Japanese Patent No. 3279164

However, the induction heating device described in Patent Document 1 is composed of an inner coil and an outer coil in which heating coils are arranged concentrically and supplies high frequency power to each coil alternately. There is a problem that the temperature of the pan above the outer coil to which no is supplied is lowered when no power is supplied.
In addition, as described above, the induction heating device described in Patent Document 1 controls the power supplied to the outer coil to be smaller than the power supplied to the inner coil in order to prevent splashing of the foodstuff. When preheating a heated object such as a frying pan, the temperature of the outer side of the pan (so-called pot skin) cannot be increased, and the temperature gradient (temperature unevenness) from the bottom of the pan to the pot skin increases during preheating. There was a problem that fried foods could not be cooked deliciously.

  On the other hand, according to the induction heating device described in Patent Document 2, from the first heating coil disposed below the center portion of the plate and the ring-shaped second coil disposed on the outer peripheral portion of the first heating coil. Since the first heating coil and the second coil are alternately energized with a period of approximately 30 seconds or less during preheating, as in Patent Document 1, above the first or second heating coil that is not energized. There was a problem that the temperature of the placed pan was lowered when no power was supplied, and a longer preheating time was required.

  Accordingly, the present invention has been made in view of the above problems, and in the preheating mode, by controlling the amount of power supplied to the peripheral coils to be larger than the amount of power supplied to the central coil, the preheating time is reduced. The aim is to realize an induction heating apparatus that can shorten and reduce the temperature variation from the bottom of the pot to the skin of the pot (by uniformly heating the pot) and deliciously cook omelets and fried foods.

  An induction heating device according to the present invention includes a central coil wound in a planar shape, one or a plurality of peripheral coils wound around the central coil, and a central coil power source that supplies power to the central coil A circuit, one or more peripheral coil power supply circuits for supplying power to the one or more peripheral coils, a control circuit for controlling the central coil power supply circuit and the peripheral coil power supply circuit, and an object to be heated A mode selection switch capable of selecting a preheating mode to be heated automatically, wherein the control circuit is configured such that high-frequency current flows in substantially the same direction in a region where the central coil and the one or more peripheral coils are adjacent to each other. In addition, the amount of power supplied to the central coil in the preheating mode is equal to the amount of power supplied to the one peripheral coil or a plurality of peripheral coils. Is characterized in that for controlling the central coil power supply circuit and the peripheral coil power supply circuit to be less than the sum of the sheet is the amount of power.

  According to the present invention, the preheating time is shortened by controlling the amount of power supplied to the central coil in the preheating mode to be smaller than (or the sum of) the amount of power supplied to one or more peripheral coils. In addition, it is possible to realize an induction heating device that can cook omelets and fried foods while suppressing variations in temperature from the bottom of the pot to the skin of the pot.

It is a schematic perspective view which shows the whole induction heating apparatus which concerns on this invention. It is a front view of the IH operation panel concerning the present invention. 3 is a plan view showing a heating coil of the IH heating unit according to Embodiment 1. FIG. 2 is a block circuit diagram of a high frequency power supply unit according to Embodiment 1. FIG. In Embodiment 1, it is a timing chart which shows the time transition of the high frequency electric power supplied to the center coil and peripheral coil in a preheating mode period. It is a graph which shows the temperature gradient of the radial direction of the pot bottom temperature at the time of performing preheating using the control circuit which concerns on Embodiment 1. FIG. 6 is a plan view showing a heating coil of an IH heating unit according to Embodiment 2. FIG. FIG. 4 is a block circuit diagram of a high frequency power supply unit according to a second embodiment. 6 is a plan view showing a heating coil according to a first modification of the second embodiment. FIG. FIG. 6 is a block circuit diagram of a high frequency power supply unit according to Modification 1 of Embodiment 2. FIG. 10 is a block circuit diagram of a high frequency power supply unit obtained by further modifying the first modification. FIG. 10 is a block circuit diagram of a high frequency power supply unit obtained by further modifying the first modification. FIG. 10 is a plan view showing a heating coil according to a second modification of the second embodiment. In Embodiment 3, it is a timing chart which shows the time transition of the high frequency electric power supplied to the center coil and peripheral coil in a preheating mode period. In Embodiment 4, it is a timing chart which shows the time transition of the high frequency electric power supplied to the center coil and peripheral coil in the preheating mode period. In Embodiment 5, it is a timing chart which shows the time transition of the high frequency electric power supplied to the center coil and peripheral coil in the preheating mode period. In Embodiment 6, it is a timing chart which shows the time transition of the high frequency electric power supplied to the center coil and peripheral coil in the preheating mode period.

  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, a term indicating a direction (for example, “upward” and “downward”) is used as appropriate for easy understanding. Does not limit the present invention. In the accompanying drawings, the same components are referred to by the same reference numerals.

Embodiment 1 FIG.
The first embodiment of the induction heating apparatus 1 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. The induction heating apparatus 1 shown in FIG. 1 schematically includes a housing 3, a top plate 4 formed of glass or the like that covers substantially the entire upper surface thereof, and first and second IH heating units arranged on the left and right sides. 10a, 10b, a radiant heating section 5, and a grill heating section 6. Each IH heating unit 10 includes an electromagnetic induction heating coil (hereinafter simply referred to as “heating coil”) 30 formed in a predetermined plane, and when a high frequency current is supplied from a high frequency power supply unit 2 described later. Then, an eddy current is formed in a pan (heated body) 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 is used for operating the heating power of the IH operation panels 12a, 12b, the radiant heating unit 5 and the grill heating unit 6 used by the user to operate the heating power of the IH heating units 10a, 10b. A heating operation panel 12, a liquid crystal display unit 14 for displaying these control states, and an intake window 16 and an exhaust window 17 provided behind the housing 3.

FIG. 2 is a front view of the IH operation panel 12 according to the present invention. Each IH operation panel 12 has an “on” switch 20, a “fry pan preheating” mode switch 21 a for preheating frying pans, and a “for frying dishes such as curry” in the upper stage (FIG. 2A). Cooking mode including a "boiled" mode switch 21b, a "warm" mode switch 21c for keeping hot salmon etc. at a constant temperature, a "hot water" mode switch 21d for boiling hot water, and a "fried food" mode switch 21e for cooking fried food It has the selection switch 21 and the temperature setting switch 22 which can set the temperature in these cooking modes.
Further, the cooking mode selection switch 21 and the temperature setting switch 22 can be used in combination. For example, each IH operation panel 12 can be used after the user selects the “frying pan preheating” mode by pressing the “frying pan preheating” mode switch 21a. The temperature setting switch 22 has a means (preheating temperature setting means) for setting the preheating temperature by selecting a desired preheating temperature.

Further, each IH operation panel 12 is pre-programmed with a “OFF” switch 24 and a “OFF timer” mode switch 25a for stopping power supply after a predetermined period of time in addition to the “OFF” switch 24 in the lower stage (FIG. 2B). “Menu” mode switch 25b for displaying a cooking menu on the liquid crystal display unit 15, “weak” mode switch 25c for setting the heating power of each IH heating unit 10, “medium” mode switch 25d, “strong” mode switch A thermal power mode selection switch 25 including 25e, and a thermal power adjustment switch 26 capable of setting thermal power (time) adjustment in these cooking modes.
Similarly, the cooking mode selection switch 21 and the heating power (time) adjustment switch 26 can be used in combination, and each IH operation panel 12 can be used in, for example, a “frying pan preheating” mode when the user presses the “frying pan preheating” mode switch 21a. After selecting “”, there is means (preheating period setting means) for setting the preheating mode time.

  FIG. 3 is a plan view showing the heating coil 30 of each IH heating unit 10 according to the first embodiment. The heating coil 30 according to the first embodiment is disposed below the top plate 4, and a central coil 32 in which a conducting wire is wound in a planar shape as shown in the figure, and a peripheral coil wound around the central coil 32 34. Each IH heating section 10 preferably includes temperature detection sensors 36a and 36b, which are disposed between the central coil 32 and the peripheral coil 34, as shown in the drawing, for detecting the temperature of the pan bottom. The temperature detection sensors 36a and 36b are not limited to this, but may be, for example, a thermistor or an infrared temperature sensor. The arrangement positions of the temperature detection sensors 36a and 36b are not limited to the positions between the central coil 32 and the peripheral coil 34, and may be inside the central coil 32 or outside the peripheral coil 34. .

  FIG. 4 is a block circuit diagram of the high frequency power supply unit 2 according to the first embodiment. The high-frequency power supply unit 2 according to the first embodiment roughly 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 all the rectifier circuits 112. Smoothing capacitor 114 for smoothing the DC voltage of wave rectification, and a full-bridge inverter circuit (power supply circuit) for central coil and peripheral coil for supplying high-frequency power independently to central coil 32 and peripheral coil 34, respectively 40, 50 (shown by broken lines in FIG. 4).

  The full-bridge inverter circuit 40 for the central coil includes a first arm 43 in which a first high-voltage side switching element 42a and a first low-voltage side switching element 42b are connected in series, a second high-voltage side switching element 44a, Two low-voltage side switching elements 44b connected in series, and the central coil 32 and the first coil 43 electrically connecting between the first arm 43 and the intermediate contacts of the second arm 45 and the first arm And a resonance capacitor 46. That is, the full-bridge inverter circuit 40 for the central coil supplies a high frequency power source (high frequency current) to the central coil 32.

Similarly, the full-bridge inverter circuit 50 for the peripheral coil includes a third arm 53 in which a third high-voltage side switching element 52a and a third low-voltage side switching element 52b are connected in series, and a fourth high-voltage side switching element. 54a and the fourth low-voltage side switching element 54b are connected in series, and the peripheral coil 34 electrically connecting between the intermediate contacts of the third arm 53 and the fourth arm 55; The second resonance capacitor 56 is used. That is, the peripheral bridge full-bridge inverter circuit 50 supplies a high frequency power source (high frequency current) to the peripheral coil 34.
Needless to say, the resonance capacitors in the full-bridge inverter circuits 40 and 50 may be arranged with their positions replaced as long as they are connected in series to the central coil 32 or the peripheral coil 34. As long as it constitutes an LCR circuit, a resonance capacitor may be connected in parallel to the central coil 32 or the peripheral coil 34.

The two full-bridge inverter circuits 40 and 50 are driven by drive signals output from the drive circuits 47, 48, 57, and 58 with respect to the two arms 43, 45, 53, and 55, respectively. , 57 and 58 are independently controlled based on a control signal output from the control circuit 70. However, the full-bridge inverter circuits 40 and 50 that supply power to the central coil 32 and the peripheral coil 34 arranged adjacent to each other have the same drive frequency in order to prevent interference sound (beating phenomenon) generated from the pan. Is controlled to supply a high-frequency current having
In other words, the control signal output from the control circuit 70 is sent to the drive circuits 47, 48, 57, 58 that output the drive signals of the arms 43, 45, 53, 55, and the switching elements 42, 44, 52, The switching operation of 54 is performed, high frequency electric power is supplied to the central coil 32 and the peripheral coil 34 of the heating coil 30, and the pot which is a to-be-heated body is induction-heated.

In addition, the control circuit 70 according to the present invention is configured so that at a certain moment (a predetermined phase of the high-frequency current), the direction of the high-frequency current flowing through the central coil 32 is counterclockwise (indicated by an arrow A in FIG. 3) The full-bridge inverter circuits 40 and 50 are controlled so that the direction of the high-frequency current flowing through the coil 34 is also counterclockwise (indicated by the arrow B in FIG. 3). That is, in the region where the central coil 32 and the peripheral coil 34 are adjacent to each other (adjacent region), the induced electromotive force generated by the central coil 32 and the peripheral coil 34 is controlled by controlling the high-frequency current to flow in the same direction. The current flowing in the bottom of the pan between the central coil 32 and the peripheral coil 34 can be increased without canceling each other out. As a result, the Joule heat generated at the bottom of the pan in the adjacent region is increased to improve the heating efficiency as the induction heating device 1, and the power loss (unnecessary) generated in the switching elements 42, 44, 52, 54 of the inverter circuits 40, 50 is increased. Heat generation amount) can be reduced. Therefore, the heat radiation fins and cooling fans (both not shown) necessary for sufficiently cooling the switching elements 42, 44, 52, 54 of the inverter circuits 40, 50 are reduced in size, weight, and cost. Can do.
Similarly, at another moment, when the direction of the high-frequency current flowing through the central coil 32 is clockwise, the control circuit 70 causes the inverter circuit 40, so that the direction of the high-frequency current flowing through the peripheral coil 34 is also clockwise. 50 is controlled.

FIG. 5 shows the time of the high-frequency power supplied to the central coil 32 and the peripheral coil 34 in the preheating mode period (T) in which a pan such as a frying pan is preliminarily heated when the “frying pan preheating” mode 21a is selected. It is a timing chart which shows transition. That control circuit 70 according to the first embodiment, when the "frying pan preheat" mode 21a is selected by the user, the power supplied to the central coil 32 (W ₁₎ and the power supplied to the peripheral coil 34 (W ₂ ) Are supplied simultaneously (constantly) with constant power (amount of power per unit time) without fluctuation in time, and the power (W ₁ ) supplied to the central coil 32 is supplied to the peripheral coil 34. The inverter circuits 40 and 50 are controlled so as to be smaller than the power (W ₂ ) (W ₁ <W ₂ ).

6 shows a case where “fry pan preheating” is performed when the control circuit 70 according to the first embodiment is used (solid line) and when the conventional control circuit described in the above-mentioned Patent Document 1 is used (broken line). It is a graph which shows how the surface temperature (pan bottom temperature) of this pan changes according to the distance of the radial direction which makes the center the origin (radial temperature gradient).
More specifically, the control circuit 70 according to the first embodiment has a ratio R (R = W) between the power (W ₁ ) supplied to the central coil 32 and the power (W ₂ ) supplied to the peripheral coil 34. ₂ / W ₁ , hereinafter, simply referred to as “internal / external power ratio”) is controlled to 3 to 7, and the conventional control circuit has an internal / external power ratio of 7 to 7. The inverter circuits 40 and 50 are controlled so as to be 3.

As is apparent from FIG. 6, the temperature gradient in the radial direction when the internal / external power ratio is 3 to 7 and 7 to 3 reaches the peak at the position indicated by the alternate long and short dash line a. This corresponds to a region where the central coil 32 and the peripheral coil 34 are adjacent to each other, and is because the magnetic fields of the central coil 32 and the peripheral coil 34 strengthen each other as described above.
Further, according to FIG. 6, the radial temperature gradient when the internal / external power ratio is 3 to 7 (first embodiment, solid line I) is the radial temperature gradient when the internal / external power ratio is 7: 3. Compared to (conventional product, broken line P), the temperature change of the pan bottom temperature is small from the center of the pan to the skin of the pan. That is, according to the induction heating device 1 according to Embodiment 1, the frying pan can be preheated at a more uniform pot bottom temperature and at a higher pot skin temperature. In this way, by fully heating the entire frying pan evenly to the pot skin during preheating, omelets and fried foods can be cooked deliciously.

As will be described in detail later, according to the present invention, the amount of power (Q ₁ = W ₁ × T) supplied to the central coil 32 in the preheating mode period (T) is the amount of power (Q ₂ ) supplied to the peripheral coil 34. = W ₂ × T), the power (W ₁ , W ₂ ) is not necessarily supplied constantly as shown in FIG. 5, and any power (W) is controlled. By controlling the supply time (T), the entire temperature of the pan bottom can be made more uniform, and the pot skin can be preheated to a higher temperature.

Further, according to the first embodiment, constant power (W ₁ , W ₂ ) is constantly and simultaneously supplied to the central coil 32 and the peripheral coil 34, so that the induction heating device described in the above-mentioned Patent Document 2 is used. As compared with the above, it is possible to preheat to a desired temperature in a shorter time.

  In addition, although the size of pans, such as a frying pan, which is generally popular, varies in size, some have an outer diameter (diameter) exceeding 180 mm. Therefore, the peripheral coil 34 according to the present invention is designed to be 190 mm to 290 mm so that its outer diameter (diameter D shown in FIG. 3) is larger than the outer diameter of most frying pans, so Variations can be suppressed and the pot skin temperature can be preheated high.

Embodiment 2. FIG.
The second embodiment of the induction heating device according to the present invention will be described in detail below with reference to FIGS. The heating coil 30 according to the first embodiment has a central coil 32 and a single peripheral coil 34 wound in a circular shape, whereas the heating coil 30 according to the second embodiment includes a peripheral coil. Since it has the same configuration as the induction heating device 1 of Embodiment 1 except that it has a plurality of peripheral coils 34a and 34b that are wound in a semicircular arc by dividing 34 in the circumferential direction, the overlapping points Description of is omitted.

FIG. 7 is a plan view showing the heating coil 30 of each IH heating unit 10 according to the second embodiment. The heating coil 30 according to the second embodiment includes a central coil 32 in which a conductive wire is wound in a planar shape as shown in the figure, and two peripherals wound in a semicircular arc shape (banana shape or pepper shape) around the center coil 32 The coils 34a and 34b are configured. That is, the two peripheral coils 34a and 34b according to the second embodiment are obtained by dividing the single peripheral coil 34 according to the first embodiment into two in the circumferential direction. At this time, the coupling coefficient between the central coil 32 and the two peripheral coils 34a and 34b according to the second embodiment is the coupling coefficient between the central coil 32 and the single peripheral coil 34 according to the first embodiment. Since it is smaller, the magnetic interaction generated between the central coil 32 and the peripheral coils 34a and 34b becomes smaller, and the power supply to these can be easily controlled.
Each IH heating unit 10 has two temperature detection sensors 36a and 36b, as in the first embodiment. The arrangement positions of the temperature detection sensors 36a, 36b are not limited to those shown in FIG.

FIG. 8 is a block circuit diagram of the high frequency power supply unit 2 according to the second embodiment. The high-frequency power supply unit 2 according to the second embodiment includes a central coil full-bridge inverter circuit 40 for supplying high-frequency power to the central coil 32, and first and second high-frequency powers for supplying the peripheral coils 34a and 34b. The second peripheral coil full-bridge inverter circuits 50 and 60 are provided.
In the control circuit 70 according to the second embodiment, as in the first embodiment, in the region where the central coil 32 and the peripheral coils 34a and 34b are adjacent to each other (adjacent region), the high-frequency current is in the same direction (the broken line in FIG. The full-bridge inverter circuit 40 for the central coil and the full-bridge inverter circuits 50 and 60 for the peripheral coils are controlled so as to flow as indicated by arrows. Thus, the heating efficiency of the induction heating device 1 can be improved, and power loss generated in the switching elements 42, 44, 52, 54, 62, 64 of the inverter circuits 40, 50, 60 can be reduced.

Further, as in the first embodiment, when the “fry pan preheating” mode 21a is selected, the control circuit 70 according to the second embodiment performs a central operation in a preheating mode period (T) in which a pan such as a frying pan is preliminarily heated. Electric power (W ₁ ) is supplied to the coil 32, and each inverter circuit 40, so that the sum (total) of electric power supplied to the peripheral coils 34 a and 34 b becomes electric power (W ₂ ) as shown in FIG. 50 and 60 are controlled. That is, in the control circuit 70 according to the second embodiment, the amount of power (Q ₁ = W ₁ × T) supplied to the central coil 32 in the preheating mode period (T) is the sum of the amounts of power supplied to the peripheral coils 34 ( By controlling each inverter circuit 40, 50, 60 so as to be smaller than ΣQ ₂ = ΣW ₂ × T), the temperature of the whole pan bottom can be made more uniform, and the pot skin can be preheated to a higher temperature. .

Modification 1
FIG. 9 is a plan view showing the heating coil 30 of each IH heating unit 10 according to the first modification of the second embodiment. The heating coil 30 according to the modified example 1 includes a central coil 32 and four peripheral coils 34a to 34d wound in a ¼ arc shape (banana shape or pepper shape) around the central coil 32. That is, the two peripheral coils 34a to 34d according to the modification 1 are obtained by dividing the single peripheral coil 34 according to the first embodiment into four in the circumferential direction. At this time, since the coupling coefficient between the central coil 32 and the four peripheral coils 34a to 34d according to the first modification can be further reduced, the magnetic interaction generated between them can be reduced. It is possible to easily control the power supply to the.

FIG. 10 is a block circuit diagram of the high frequency power supply unit 2 according to the first modification. Opposing peripheral coils 34a, 34c and 34b, 34d of Modification 1 are connected in parallel. In other words, the high frequency power supply unit 2 of the first modification includes a full-bridge inverter circuit 40 for supplying a high frequency power to the central coil 32, the peripheral coils 34a and 34c, and the peripheral coils 34b and 34d. First and second peripheral coil full-bridge inverter circuits 50 and 60 for supplying electric power are provided.
As in the first and second embodiments, the control circuit 70 according to the first modified example has a high-frequency current in the same direction (an adjacent region) in which the central coil 32 and the peripheral coils 34a to 34d are adjacent to each other (in FIG. 9). The full-bridge inverter circuit 40 for the central coil and the full-bridge inverter circuits 50 and 60 for the peripheral coils are controlled so as to flow in the direction indicated by broken arrows. Thus, the heating efficiency of the induction heating device 1 can be improved, and power loss generated in the switching elements 42, 44, 52, 54, 62, 64 of the inverter circuits 40, 50, 60 can be reduced.

Instead of connecting the opposing peripheral coils 34a, 34c and 34b, 34d in the first modification in parallel, the adjacent peripheral coils 34a, 34b and 34c, 34d may be connected in parallel.
Moreover, as shown in FIG. 11, all the peripheral coils 34a-34d of the modified example 1 are connected in parallel, and this is configured to supply high-frequency power from a single peripheral coil full-bridge inverter circuit 50, The control circuit 70 may control the central coil full-bridge inverter circuit 40 and the single peripheral coil full-bridge inverter circuit 50.
Further alternatively, as shown in FIG. 12, the peripheral coils 34a, 34c and 34b, 34d of the first modification are connected in parallel and connected to a single full bridge for peripheral coils. The high frequency power is supplied from the inverter circuit 50, and the control circuit 70 similarly controls the full bridge inverter circuit 40 for the central coil and the full bridge inverter circuit 50 for the single peripheral coil. Also good.
Thus, in the first modification, adjacent peripheral coils 34a, 34b and 34c, 34d may be connected in parallel, or a plurality of arbitrarily selected peripheral coils 34 may be connected in series instead of being connected in parallel. Also good.

Modification 2
FIG. 13 is a plan view showing the heating coil 30 of each IH heating unit 10a, 10b according to the second modification of the second embodiment. The heating coil 30 according to the modified example 2 is modified example 1 except that six peripheral coils 34a to 34f wound in a 1/6 arc shape (banana shape or pepper shape) are arranged around the central coil 32. It has the same configuration as. Further, although not shown in detail, the high-frequency power supply unit 2 according to the modified example 2 has power for a central coil full-bridge inverter circuit 40 and a plurality of arbitrarily selected peripheral coils 34 connected in parallel or in series. And one or more full-bridge inverter circuits 50 for supplying the same.

As described above, the heating coil 30 according to the second embodiment may include a plurality of peripheral coils 34 divided into an arbitrary number.
Further, although the central coil 32 has been described as having a circular planar shape, the central coil 32 may have a polygonal shape such as a quadrangle or a rectangle. Similarly, the peripheral coil may have an arbitrary shape such as a quadrangle, a rectangle, a circle, an ellipse, or a bowl.
Further, the central coil 32 and each peripheral coil 34 may be on the same plane, or may be configured to overlap (arrange in a double or triple manner) in the vertical direction.

When the “fry pan preheating” mode 21 a is selected, the control circuit 70 according to the first and second modifications receives the electric energy (Q ₁ = W ₁ × T) supplied to the central coil 32 to the peripheral coil 34. Each inverter circuit 40, 50, 60 is controlled so as to be smaller than the sum of the amount of electric power (ΣQ ₂ = ΣW ₂ × T). For example, in the preheating mode period (T), power (W ₁ ) is constantly supplied to the central coil 32, and at the same time, the sum of the power supplied to the peripheral coils 34a to 34f is the power (W ₂ ) By supplying so that it may become, the temperature of the whole pan bottom can be made more uniform, and the pot skin can be preheated to a higher temperature.

  Furthermore, as described above, the diameter D of the peripheral coil 34 shown in FIGS. 7, 9 and 13 is designed to be 190 mm to 290 mm so as to be larger than the outer diameter of many widely used frying pans. It is preferable to suppress the variation in the pot bottom temperature during preheating and to preheat the pot skin temperature high.

Embodiment 3 FIG.
The third embodiment of the induction heating apparatus 1 according to the present invention will be described in detail below with reference to FIG. The control circuit 70 according to the third embodiment supplies each inverter circuit such that the power (W ₁ ) is intermittently supplied to the central coil 32 and the same power (W ₁ ) is constantly supplied to the peripheral coil 34. Since it has the same structure as the induction heating apparatus 1 of Embodiment 1 except the point which controls 40 and 50, description is abbreviate | omitted about the overlapping point.

FIG. 14 is a timing chart showing a time transition of the high-frequency power supplied to the central coil 32 and the peripheral coil 34 according to the third embodiment in the preheating mode period (T). Here, the preheating mode period (T) includes a first preheating period (T ₁ ) from the start of the preheating mode to time T ₁ and a second period from time T ₁ to the end of the preheating mode (until time T ₂ ). A preheating period.
Specifically, the control circuit 70 according to the third embodiment applies the same power (W ₁ ) to the central coil 32 and the peripheral coil 34 in the first preheating period (T ₁ ) of the preheating mode period (T). In the second preheating period (T ₂ ), the same power (W ₁ ) is continuously supplied to the peripheral coil 34 while the central coil 32 is supplied with power (W ₁ ) The inverter circuits 40 and 50 are controlled so as to supply intermittently. Here, “intermittently supplying power” means providing a partial time during which power is not supplied without changing the magnitude of the supplied power.

In the induction heating apparatus 1 according to the third embodiment configured as described above, the amount of power (Q ₁ ) supplied to the central coil 32 in the preheating mode period (T) is the amount of power (Q ₁ ) supplied to the peripheral coil 34. ₂ ) By controlling to become smaller, the temperature of the whole pan bottom can be made more uniform, and the pan skin can be preheated to a higher temperature.

Note that the control circuit 70 according to the third embodiment can be equally applied to the induction heating device 1 according to the second embodiment, and in the first preheating period (T ₁ ) of the preheating mode period (T). The power (W ₁ ) is steadily supplied to the plurality of peripheral coils 34a and 34b as the total power, and the power (W ₁ ) is supplied to the plurality of peripheral coils 34a and 34b during the second preheating period (T ₂ ). _The inverter circuits 40 and 50 may be controlled so that the power (W ₁ ) is intermittently supplied to the central coil 32 while ₁ ) is constantly supplied.

Embodiment 4 FIG.
The fourth embodiment of the induction heating apparatus 1 according to the present invention will be described in detail below with reference to FIG. The control circuit 70 according to the fourth embodiment intermittently supplies power (W ₁ ) to the central coil 32 and also supplies the same power (W ₁ ) when supplying power to the central coil 32 with respect to the peripheral coil 34. ) supply, and so on when stopping the power supply to the central coil 32 to supply electric power (W ₁₎ greater than the power (W _2), except for controlling the respective inverter circuits 40 and 50, carried Since it has the structure similar to the induction heating apparatus 1 of the form 1, it abbreviate | omits description about the overlapping point.

FIG. 15 is a timing chart showing a time transition of the high frequency power supplied to the central coil 32 and the peripheral coil 34 according to the fourth embodiment in the preheating mode period (T).
Specifically, the control circuit 70 according to the fourth embodiment applies the same power (W ₁ ) to the central coil 32 and the peripheral coil 34 in the first preheating period (T ₁ ) of the preheating mode period (T). At the same time (steady), during the second preheating period (T ₂ ), when power is supplied to the central coil 32 with respect to the peripheral coil 34 (ΔT ₁ ), the same power (W ₁ ) continues. ) Is constantly supplied, and when the power supply to the central coil 32 is stopped (ΔT ₂ ), each inverter circuit 40 is supplied so as to supply power (W ₂ ) greater than the power (W ₁ ). , 50 are controlled.
Thus, in the induction heating apparatus 1 according to the fourth embodiment, the amount of power (Q ₁ ) supplied to the central coil 32 in the preheating mode period (T) is smaller than the amount of power (Q ₂ ) supplied to the peripheral coil 34. By controlling in this way, the temperature of the whole pan bottom can be made more uniform, and the pot skin can be preheated to a higher temperature.

Embodiment 5 FIG.
A fifth embodiment of the induction heating apparatus 1 according to the present invention will be described in detail below with reference to FIG. In the first preheating period (T ₁ ) of the preheating mode period (T), the control circuit 70 according to the fifth embodiment constantly supplies power (W ₁ ) to the central coil and supplies power (W _1). ) greater power _{(W 2)} constantly supplied to the peripheral coils, in the second preheating period of the preheating mode period (T) _{(T 2),} the power _{(W 1)} is smaller than the power _{(W 1} ') the while constantly supplied to the central coil, the power (W ₂₎ greater power (W ₂ ') so as to constantly supplied to the peripheral coils, a point of controlling the central coil power supply circuit and the peripheral coil power supply circuit Except for this, since it has the same configuration as that of the induction heating apparatus 1 of the first embodiment, the description of the overlapping points is omitted.

FIG. 16 is a timing chart showing a time transition of the high frequency power supplied to the central coil 32 and the peripheral coil 34 according to the fifth embodiment in the preheating mode period (T).
Specifically, the control circuit 70 according to the fifth embodiment steadily supplies power (W ₁ ) to the central coil 32 during the first preheating period (T ₁ ) of the preheating mode period (T). , power _{(W 1)} greater than the power _{(W 2)} was constantly supplied to the peripheral coil 34, the second preheating period of the preheating mode period _(T) (T _2), the power to the center coil 32 (W ₁₎ smaller power (W ₁ ') while constantly supplied even greater power than the power (W ₂₎ is surrounded coil 34 (W _2' from the) to constantly supply, each Inverter circuits 40 and 50 are controlled. That is, in the control circuit 70 according to the fifth embodiment, the above-described internal / external power ratio (R = W ₂ / W ₁ ) is, for example, 3 to 7 in the first preheating period (T ₁ ). In the period (T ₂ ), the inverter circuits 40 and 50 are controlled so as to increase to 2 to 8.

Thus, in the induction heating apparatus 1 according to Embodiment 5, the amount of power (Q ₁ ) supplied to the central coil 32 in the preheating mode period (T) is smaller than the amount of power (Q ₂ ) supplied to the peripheral coil 34. By controlling in this way, the temperature of the whole pan bottom can be made more uniform, and the pot skin can be preheated to a higher temperature.

Referring again to FIG. 3, each IH heating unit 10 includes temperature detection sensors 36 a and 36 b disposed between the central coil 32 and the peripheral coil 34. The first preheating period (T ₁ ) in the preheating mode period (T) may be set in advance as a predetermined time (for example, after 60 seconds) that has elapsed since the start of the preheating mode, but the temperature detection sensors 36a, You may set as a variable period until the temperature detected by 36b reaches predetermined temperature.

The control circuit 70 may adjust the internal / external power ratio R depending on the rate of temperature increase detected by the temperature detection sensors 36a and 36b, or the temperature detected by the temperature detection sensors 36a and 36b. Based on the above, the preheating mode period (T) is divided into three or more preheating periods (T _{1 to} T ₃ ), and power corresponding to different internal / external power ratios R is supplied to the central coil 32 and the peripheral coil 34. In this way, the inverter circuits 40 and 50 may be controlled.

Embodiment 6 FIG.
Embodiment 6 of the induction heating apparatus 1 according to the present invention will be described in detail below with reference to FIG. In the first preheating period (T ₁ ) of the preheating mode period (T), the control circuit 70 according to the sixth embodiment steadily supplies power (W ₁ ) to the central coil 32 and supplies power (W ₁ ) is greater than power _{(W 2)} constantly supplied to the peripheral coil 34, in the second preheating period of the preheating mode period (T) _{(T 2),} the power _{(W 1)} is smaller than the power _{(W 1} ' ) intermittently supplied to the center coil 32, the power (W ₂₎ greater than the power (W ₂ ') and to constantly supplied to the peripheral coil 34, except for controlling the respective inverter circuits 40 and 50 Since it has the same configuration as the induction heating device 1 of the first embodiment, the description of the overlapping points is omitted.

FIG. 17 is a timing chart showing a time transition of the high frequency power supplied to the central coil 32 and the peripheral coil 34 according to the sixth embodiment in the preheating mode period (T).
Specifically, the control circuit 70 according to the sixth embodiment steadily supplies power (W ₁ ) to the central coil 32 during the first preheating period (T ₁ ) of the preheating mode period (T). , power _{(W 1)} greater than the power _{(W 2)} was constantly supplied to the peripheral coil 34, the second preheating period of the preheating mode period _(T) (T _2), the power to the center coil 32 _{(W 1)} 'intermittently supplying power to the peripheral coil 34 _{(W 2)} greater than the power _{(W 2} smaller than the power _{(W 1)'} a) so as to constantly supply, the inverter circuits 40 , 50 are controlled.

Thus, in the induction heating apparatus 1 according to the sixth embodiment, the amount of power (Q ₁ ) supplied to the central coil 32 in the preheating mode period (T) is smaller than the amount of power (Q ₂ ) supplied to the peripheral coil 34. By controlling in this way, the temperature of the whole pan bottom can be made more uniform, and the pot skin can be preheated to a higher temperature.

Note that the control circuit 70 according to the fourth to sixth embodiments can also be applied to the induction heating apparatus 1 having the plurality of peripheral coils 34 as described in the second embodiment. At this time, “the electric power (W ₂ ) or the electric energy (Q ₂ ) supplied to the peripheral coil 34” is “the sum of electric power (ΣW ₂ ) or the electric energy (ΣQ) supplied to the plurality of peripheral coils 34”. ₂ ) ”.

Embodiment 7 FIG.
With reference to FIG. 2 again, Embodiment 7 of the induction heating apparatus 1 according to the present invention will be described in detail below.
The IH operation panel 12 shown in FIG. 2A includes an “ON” switch 20, a cooking mode selection switch 21 including a “fry pan preheating” mode 21 a, and a temperature setting switch 22.
In the case of cooking that requires preheating, such as grilled foods and fried foods, the amount of power (Q ₂ ) supplied to the peripheral coil 34 (or supplied to a plurality of peripheral coils 34 by pressing the “fry pan preheating” mode 21a in FIG. To be larger than the sum of the electric power (ΣQ ₂ )). In the case of cooking that does not require preheating, the heating power is adjusted by the normal temperature setting switch 22 or the heating power adjustment switch 26. Thus, various cooking methods can be appropriately controlled by changing the heating pattern in cooking that requires preheating, such as grilled foods and fried foods.

When the “weak” mode switch 25c, “medium” mode switch 25d, and “strong” mode switch 25e for setting the heating power of the IH operation panel 12 are selected, preheating is performed at 160 ° C., 180 ° C., and 200 ° C., for example. The reservation mode period (T) may be ended based on the temperature of the pan detected by the temperature detection sensors 36a and 36b as described above.
Furthermore, the control circuit 70 has a memory (not shown) for storing a cooking program that can be set in accordance with the cooking mode. For example, in the cooking that requires preheating such as grilled food and fried food, each heating coil 30 is provided. The temperature (and time) programmed according to the specific cooking mode may be realized by changing the electric power (W) or the electric energy (Q) supplied to.

1: induction heating device, 2: high frequency power supply unit, 3: housing, 4: top plate, 5: radiant heating unit, 6: grill heating unit, 10: IH heating unit, 12: heating operation panel, 14: liquid crystal display Part: 16: intake window, 17 exhaust window, 21: cooking mode selection switch ("frying pan preheating" mode switch), 22: temperature setting switch, 25: thermal power mode selection switch, 26: thermal power adjustment switch, 30: heating coil, 32: Central coil, 34: Peripheral coil, 36: Sensor for temperature detection, 40, 50, 60: Inverter circuit (power supply circuit), 42, 44, 52, 54, 62, 64: Switching element, 43, 45, 53 55, 63, 65: Arm, 46, 56, 66: Resonance capacitor, 47, 48, 57, 58, 67, 68: Drive circuit, 70: Control circuit, 110: Quotient AC power source, 112: rectifier circuit, 114: smoothing capacitor.

Claims (12)

A central coil wound in a plane,
One or more peripheral coils wound around the central coil;
A central coil power supply circuit for supplying power to the central coil;
One or more peripheral coil power supply circuits for supplying power to the one or more peripheral coils;
A control circuit for controlling the central coil power supply circuit and the peripheral coil power supply circuit;
A mode selection switch capable of selecting a preheating mode for preheating the object to be heated;
The control circuit is configured so that high-frequency current flows in substantially the same direction in a region where the central coil and the one or more peripheral coils are adjacent to each other, and the amount of electric power supplied to the central coil in a preheating mode is And controlling the central coil power supply circuit and the peripheral coil power supply circuit so as to be smaller than the amount of power supplied to the one peripheral coil or the sum of the amounts of power supplied to the plurality of peripheral coils. Heating device.   The induction heating apparatus according to claim 1, wherein the plurality of peripheral coils are wound around the center coil and are electrically connected to each other in series or in parallel.   The induction heating apparatus according to claim 1 or 2, wherein a diameter of a heating coil including a central coil and one or a plurality of peripheral coils has a circular shape with a diameter of 190 mm or more. The control circuit constantly supplies the first power (W ₁ ) to the central coil during the preheating mode period (T) in which the object to be heated is preliminarily heated, and the first power (W ₁ ) larger than the _first power (W ₁ ). The induction heating according to any one of claims 1 to 3, wherein the central coil power supply circuit and the peripheral coil power supply circuit are controlled so as to constantly supply power (W2) of ₂ to the peripheral coil. apparatus. The control circuit intermittently supplies the first power (W ₁ ) to the central coil in the preheating mode period (T) in which the object to be heated is preliminarily heated, and the first power (W ₁ ) is supplied to the peripheral coil. The induction heating device according to any one of claims 1 to 3, wherein the central coil power supply circuit and the peripheral coil power supply circuit are controlled so as to be constantly supplied to the coil. The control circuit intermittently supplies the first power (W ₁ ) to the central coil in the preheating mode period (T) in which the object to be heated is preliminarily heated, and supplies power to the central coil with respect to the peripheral coils. The first power (W ₁ ) is supplied when the power is being supplied, and the second power (W ₂ ) greater than the _first power (W ₁ ) is supplied when the power supply to the central coil is stopped. The induction heating apparatus according to claim 1, wherein the central coil power supply circuit and the peripheral coil power supply circuit are controlled. The control circuit steadily supplies the first electric power (W ₁ ) to the central coil in the first preheating period (T ₁ ) of the preheating mode period (T) in which the object to be heated is preliminarily heated. The second electric power (W ₂ ) larger than the _first electric power (W ₁ ) is steadily supplied to the peripheral coils, and in the second preheating period (T ₂ ) of the preheating mode period (T), the first electric power (W ₂ ) supplies power (W ₁₎ is smaller than the power (W ₁ ') and while constantly supplied to the central coil, the second power (W ₂₎ greater than the power (W _2' a) around the coil constantly The induction heating apparatus according to claim 1, wherein the central coil power supply circuit and the peripheral coil power supply circuit are controlled as described above. The control circuit steadily supplies the first power (W ₁ ) to the central coil in the first preheating period (T ₁ ) of the preheating mode period (T) in which the object to be heated is preliminarily heated. A second electric power (W ₂ ) larger than the _first electric power (W ₁ ) is constantly supplied to the peripheral coil, and the first pre-heating period (T ₂ ) of the pre-heating mode period (T) is 'intermittently supplied to the central coil, the second power (W ₂₎ greater than the power (W ₂ power (W ₁₎ is smaller than the power (W _1)' to constantly supply) to the peripheral coil The induction heating apparatus according to claim 1, wherein the central coil power supply circuit and the peripheral coil power supply circuit are controlled. A temperature sensor disposed between the central coil and the peripheral coil for detecting the surface temperature of the object to be heated;
The control circuit includes a first preheating period (T ₁₎ based on the temperature detected by the temperature sensor in the transition to the second preheating period (T _2), near the second preheating period (T ₂₎ The power supplied to the coil and the power supplied to the central coil are determined, and the central coil power supply circuit and the peripheral coil power supply circuit are controlled so that the determined power is supplied to the peripheral coil and the central coil. The induction heating apparatus according to claim 7 or 8. A temperature sensor disposed between the central coil and the peripheral coil for detecting the surface temperature of the object to be heated;
When the temperature detected by the temperature sensor reaches a predetermined temperature, the control circuit determines that the first preheating period (T ₁ ) has shifted to the _second preheating period (T ₂ ). The induction heating device according to any one of claims 7 to 9.   The induction heating apparatus according to any one of claims 4 to 10, further comprising a preheating temperature setting means capable of setting a preheating temperature when the preheating mode period (T) ends.   The induction heating apparatus according to any one of claims 4 to 10, further comprising preheating period setting means capable of setting a preheating mode period (T).

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