JP5369202B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker that induction-heats a cooking container.

In recent years, induction heating cookers in which cooking containers such as pans are induction-heated by a heating coil have become widespread. As a conventional induction heating cooker, one that heats a pan placed on a top plate with a single heating coil is known. However, in such a conventional induction heating cooker, when the size of the pan bottom is larger than the outer diameter of the heating coil, there is a problem that the heating amount of the outer peripheral portion of the pan becomes relatively small and the cooking performance is impaired. .
Against the background of these problems, as an induction heating cooker that can heat a large pan, in addition to the heating coil disposed in the center of the heating port, an auxiliary heating coil is disposed on the outer peripheral portion, and a single pan Induction heating configured to heat with a heating coil, and “determine each power so that the power ratio between the first heating coil 2a and the plurality of heating coil groups 2b to 2g is always substantially constant”. A cooker has been proposed (see, for example, Patent Document 1).

JP 2010-073384 (page 8, FIG. 4)

  By the way, in recent years, a pan made of a magnetic material such as stainless steel is attached to the center of the bottom of a pan container made of a low-resistance nonmagnetic material such as aluminum, and the pan is designed to generate heat at the center of the pan bottom (hereinafter referred to as a pasting pan). There are many). When such a ladle is placed on the top plate, a magnetic plate is positioned on the central heating coil, and a part of the magnetic plate and a low-resistance nonmagnetic material are placed on the outer heating coil. In many cases, the arrangement is such that the pot container made of is located. Therefore, the heating coil in the central part mainly heats the plate made of magnetic material, and the heating coil in the outer peripheral part induction heats a part of the plate made of magnetic material and the pan container made of a low-resistance nonmagnetic material. .

Generally, non-magnetic materials have lower efficiency during induction heating than magnetic materials, so the circuit loss when induction heating non-magnetic materials is larger than the circuit loss when induction heating magnetic materials. . Therefore, when induction heating the pasting pan as described above, when the power control is performed so that the power ratio of the heating coil between the central portion and the outer peripheral portion is constant as disclosed in Patent Document 1, the central portion is disposed in the central portion. Compared with the driving circuit for the heating coil, the driving state in which the driving circuit for the heating coil arranged on the outer peripheral portion is large is brought about.
Also, normally, the drive circuit of the heating coil is set with an allowable loss that is determined by the cooling performance of the cooling fins that send cooling air to the heat radiating fins or the drive circuit. Be controlled.

  For this reason, when it is the structure which carries out electric power control so that the power ratio of the heating coil of a center part and an outer peripheral part becomes fixed like the induction heating cooking appliance of the said patent document 1, the outer periphery used as a comparatively big value The circuit loss of the driving circuit of the heating coil in the part is restricted, and sufficient input power cannot be input to the heating coil in the outer peripheral part, and accordingly, the input power of the heating coil in the central part is also limited. Then, since the electric power that heats the pan is the total value of the electric power of the heating coil in the central part and the heating coil in the outer peripheral part, this total input electric power becomes a small value with respect to the set thermal power, and is pasted. There was a problem that sufficient input power could not be obtained when heating the pan.

  The present invention has been made in order to solve the above-described problems. Even when induction heating is performed on a pan with a magnetic material attached to the center of the pan bottom, induction heating can be performed without limiting power. A cooker is provided.

  An induction heating cooker according to the present invention includes a first heating coil, a second heating coil disposed on an outer peripheral side of the first heating coil, and a first high-frequency power supply unit that supplies an alternating current to the first heating coil. A second high-frequency power supply that supplies an alternating current to the second heating coil, a first coil current detector that detects a current flowing through the first heating coil, and a current flowing through the second heating coil A second coil current detector; a first power detector for detecting output power of the first high frequency power supply; a second power detector for detecting output power of the second high frequency power supply; and the first heating. A control unit that controls the first high-frequency power supply unit and the second high-frequency power supply unit so that the total output power from the coil and the second heating coil is equal to a set thermal power, and the control unit The first power detection unit and From the detection result of the first coil current detection unit and the detection result of the second power detection unit and the second coil current detection unit, respectively, the heating load placed on the first heating coil and the second The material of the heating load placed on the heating coil is detected, and when the heating load on the first heating coil is different from the heating load on the second heating coil, the output power of the second high frequency power supply unit On the other hand, a first heating coil priority mode for controlling the output power of the first high-frequency power supply unit to be large is provided.

  According to the present invention, the pasting pan can be induction-heated without limiting the output power of the entire heating port.

3 is a top view of the induction heating cooker according to Embodiment 1. FIG. It is a figure explaining the structure of the heating coil of the right heating port of the induction heating cooking appliance which concerns on Embodiment 1. FIG. It is a circuit block diagram of the induction heating cooking appliance which concerns on Embodiment 1. FIG. It is a figure which shows the relationship between the drive signal of the inverter circuit of the induction heating cooking appliance which concerns on Embodiment 1, and input electric power. It is a figure explaining the relationship between the input electric power to an inverter circuit, and an inverter circuit loss. It is a discrimination | determination characteristic view of the pan load based on the relationship between the input electric power in the induction heating cooking appliance which concerns on Embodiment 1, and the electric current value of a heating coil. It is a figure which shows the combination of the detection result of the pot material in the load determination process of the induction heating cooking appliance which concerns on Embodiment 1. FIG. It is a figure explaining the structural example of a sticking pan. It is a figure explaining the state which mounted the sticking pan in the right heating port of the induction heating cooking appliance which concerns on Embodiment 1. FIG. It is a figure which shows the relationship between setting thermal power and input electric power in the case of carrying out induction heating of a magnetic pan or a high resistance nonmagnetic pan in the induction heating cooking appliance which concerns on Embodiment 1. FIG. It is a figure which shows the relationship between setting thermal power and input electric power in the case of carrying out induction heating of the sticking pan in the induction heating cooking appliance which concerns on Embodiment 1. FIG. It is a figure explaining the relationship between input electric power and an inverter circuit loss in the case of carrying out induction heating of the high resistance nonmagnetic pan in the induction heating cooking appliance which concerns on Embodiment 3. FIG. It is a figure which shows the relationship between setting thermal power and input electric power in the case of carrying out induction heating of the sticking pan in the induction heating cooking appliance which concerns on Embodiment 3. FIG.

  Embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by the form of drawing shown below.

Embodiment 1 FIG.
1 is a top view of the induction heating cooker according to Embodiment 1. FIG.
The heat-resistant top plate 1 on which the pan is placed has a total of three heating ports, a right heating port 2, a left heating port 3, and a central heating port 4. A heating coil 5 and a heating coil 6 are installed below the right heating port 2 and the left heating port 3 (note that the heating coil 5 and the heating coil 6 are shown by solid lines for convenience), and are mounted on the upper part of the heating port. The placed pan is induction heated with a high frequency magnetic field generated from a heating coil. Further, the top plate 1 is provided with an operation / display unit 8 for accepting the operation of the switch by the user and displaying the heating conditions of the induction heating cooker and information for the user. Adjustment of the thermal power and selection of the heating port are performed by operating the operation / display unit 8. The operation / display unit 8 includes a display device such as a liquid crystal panel as display means. The operation / display unit 8 may be provided for each heating port, or the operation unit and the display unit corresponding to each heating port may be provided in one place, and the specific configuration is not particularly limited. Absent.

  In this Embodiment 1, the case where the structure which concerns on this invention is applied to the right heating port 2 among the three heating ports provided in the heating cooker is demonstrated to an example. For this reason, below, it demonstrates focusing on the structure which concerns on the right heating port 2. FIG.

FIG. 2 is a diagram illustrating the configuration of the heating coil of the right heating port of the induction heating cooker according to the first embodiment.
The heating coil 5 provided in the right heating port 2 includes a main coil 51 and an auxiliary coil 52. The main coil 51 has an outer shape formed into a disk shape. The auxiliary coil 52 is formed in an annular shape having a diameter larger than that of the main coil 51, and is arranged substantially concentrically with the main coil 51 on the outer peripheral side of the main coil 51. The main coil 51 and the auxiliary coil 52 are connected to different drive circuits, and are energized independently.

FIG. 3 is a circuit configuration diagram of the induction heating cooker according to the first embodiment, and mainly shows a drive circuit for the right heating port.
In FIG. 3, a circuit group related to the main coil 51 is shown as a circuit 30, and a circuit group related to the auxiliary coil 52 is shown as a circuit 31.

  The circuit 30 related to the main coil 51 includes an input current detection circuit 10, a DC power supply circuit 11, an inverter circuit 12, a coil current detection circuit 15, and a load circuit 18.

  The input current detection circuit 10 detects a current input from the commercial power supply 9 to the DC power supply circuit 11 and outputs an analog voltage signal corresponding to the input current value to the control circuit 13.

  The DC power supply circuit 11 includes a diode bridge 21, a choke coil 22, and a smoothing capacitor 23, converts alternating current input from the commercial power supply 9 into direct current, and outputs the direct current to the inverter circuit 12.

  The inverter circuit 12 is a so-called half-bridge type inverter in which an IGBT 24 and an IGBT 25 as switching elements are connected in series to an output point of the DC power supply circuit 11. The inverter circuit 12 converts the DC power output from the DC power supply circuit 11 into high frequency power of about 20 kHz to 50 kHz, and supplies the high frequency power to the resonance circuit including the main coil 51 and the resonance capacitor 16. By doing so, a high frequency current of about several tens of A flows through the main coil 51, and the pan placed on the top plate 1 immediately above the main coil 51 is induction-heated by the high frequency magnetic field. The IGBTs 24 and IGBTs 25 that are switching elements are made of, for example, a semiconductor made of a silicon-based material.

  The coil current detection circuit 15 is connected between the main coil 51 and the inverter circuit 12. The coil current detection circuit 15 detects the peak of the current flowing through the main coil 51 and outputs an analog voltage signal corresponding to the peak value of the heating coil current to the control circuit 13.

  The load circuit 18 includes a resonance circuit configured by a main coil 51 and a resonance capacitor 16 connected in series, and a clamp diode 17. One end of the main coil 51 is connected to a connection point between the IGBT 24 and the IGBT 25 via a connection line, and the other end of the main coil 51 is connected to one end of the resonance capacitor 16 via a connection line. The other end of the resonance capacitor 16 is connected to the IGBT 25. The clamp diode 17 is connected between the connection point of the main coil 51 and the resonance capacitor 16 and the low potential side bus of the DC power supply circuit 11, and the potential of the connection point of the main coil 51 and the resonance capacitor 16 is on the low potential side. Clamp so that it does not drop below the bus potential.

  A snubber capacitor 14 is connected in parallel to the IGBT 25. The snubber capacitor 14 has a function of reducing the switching loss by smoothing the rise of the voltage waveform when the IGBT 24 and the IGBT 25 are turned off.

  The control circuit 13 calculates input power from the integration of the input current value detected via the input current detection circuit 10 and the commercial power supply voltage. Then, for example, by varying the drive signals of the IGBT 24 and the IGBT 25 provided in the inverter circuit 12 so as to be the input power corresponding to the target power provided for each set thermal power set by the operation / display unit 8, Perform power feedback control.

  Here, in the first embodiment, as described above, the control circuit 13 calculates the input power value obtained by integrating the input current value detected by the input current detection circuit 10 and the commercial power supply voltage as the output of the inverter circuit 12. It shall be regarded as a power value. Strictly speaking, since there is a loss in the DC power supply circuit 11 and the inverter circuit 12, the value of the input power calculated as described above is not equal to the value of the output power. The power value is used as the output power of the inverter circuit 12. That is, the “input current detection circuit 10” and the “control circuit 13” of the first embodiment function as the “first power detection unit” of the present invention.

  An input current detection circuit 60, a DC power supply circuit 61, an inverter circuit 62, a snubber capacitor 64, a coil current detection circuit 65, a resonance capacitor 66, a clamp diode 67, a load circuit 68, and a diode bridge 71 constituting the circuit 31 related to the auxiliary coil 52. , Choke coil 72, smoothing capacitor 73, IGBT 74, IGBT 75 are input current detection circuit 10, DC power supply circuit 11, inverter circuit 12, snubber capacitor 14, coil current detection circuit 15, resonance capacitor 16, clamp diode in circuit 30, respectively. 17, the load circuit 18, the diode bridge 21, the choke coil 22, the smoothing capacitor 23, the IGBT 24, and the IGBT 25, and detailed description thereof is omitted here.

FIG. 4 is a diagram showing a relationship between the drive signal of the inverter circuit of the induction heating cooker according to Embodiment 1 and the input power.
FIG. 4A is a diagram showing the relationship between the frequency of the inverter circuit 12 and the inverter circuit 62 and the energization ratio of the high-potential side IGBT (IGBT 24, IGBT 74). In the induction heating cooker shown in the first embodiment, as shown in FIG. 4A, only the energization ratio is in the range of 1% to 49%, for example, with the drive frequency fixed at a constant value (for example, 24 kHz). Control power by varying. This is because, when a plurality of heating coils are arranged close to each other and each heating coil is driven at a different frequency, an interference sound corresponding to the frequency difference is generated. By controlling the power as shown in FIG. 4A, the two coils, the main coil 51 and the auxiliary coil 52, which are arranged close to each other, are driven at the same frequency. There is no occurrence.

  FIG. 4B is a diagram illustrating the relationship between the energization ratio and the input power of the inverter circuit 12 and the inverter circuit 62. As described with reference to FIG. 4A, by changing the energization ratio of the high potential IGBT (IGBT 24, IGBT 74) from 1% to 49% in a state where the frequency is constant, the input is made according to the energization ratio. The power can be varied, for example, in the range of 100W to 2000W.

Next, the difference in the relationship between input power and inverter circuit loss due to the material of the pan will be described.
FIG. 5 is a diagram illustrating the relationship between the input power to the inverter circuit and the inverter circuit loss.
First, the material of the pan serving as a heating load is roughly divided into a magnetic material such as iron and SUS430, a high resistance nonmagnetic material such as SUS304, and a low resistance nonmagnetic material such as aluminum and copper. In FIG. 5, reference numeral 33 is a line showing the relationship between the loss of the inverter circuit and the input power in a state where a pan made of a magnetic material (hereinafter sometimes referred to as a magnetic pan) is placed, and reference numeral 34 is a high resistance. It is the line which shows the relationship between the loss of an inverter circuit, and input power in the state which mounted the pan (it may be hereafter called a high resistance nonmagnetic pan) which consists of nonmagnetic materials. Reference numeral 32 denotes a line indicating the allowable loss of the inverter circuit. This permissible loss is a value determined by the cooling performance such as the airflow of a cooling fan that supplies cooling air to the radiating fin of the inverter circuit and the inverter circuit.
In addition, in order to induction-heat low resistance nonmagnetic materials, such as aluminum, a special resonance circuit is required, and the induction heating cooker of this Embodiment 1 is used for induction heating of the pan which consists of low resistance nonmagnetic materials. Since it does not correspond, description is omitted in FIG.

As shown in FIG. 5, in the entire range of input power, the value of the loss (reference numeral 33) of the inverter circuit when the magnetic pan is placed is the value of the inverter circuit when the high resistance non-magnetic pan is placed. It is smaller than the value of the loss (symbol 34). The rate of increase in the inverter circuit loss (symbol 33) when the magnetic pan is placed is also higher than the rate of increase in the inverter circuit loss (symbol 34) when the high-resistance nonmagnetic pan is placed. small.
And in the example shown in FIG. 5, the loss (code | symbol 33) of the inverter circuit at the time of mounting a magnetic pan is below an allowable loss (code | symbol 32) in the whole range of input electric power. On the other hand, when the high-resistance nonmagnetic pan is placed, the loss of the inverter circuit (reference numeral 34) exceeds the allowable loss (reference numeral 32) in a range where the input power is large.

  The allowable loss 32 is a value determined by the cooling performance defined by the radiating fins and the amount of cooling air and is not generally defined, but at least when a high-resistance non-magnetic pan is placed, the magnetic pan It can be seen that the loss of the inverter circuit becomes larger than when the is mounted. Generally, a high resistance non-magnetic pan has a smaller impedance in a state where it is placed on a heating coil than a magnetic pan. Therefore, when the nonmagnetic pan is driven with the same input power as the magnetic pan, the load current flowing through the heating coil and the switching element tends to increase.

The “main coil 51” in the first embodiment corresponds to the “first heating coil” of the present invention.
The “auxiliary coil 52” in the first embodiment corresponds to the “second heating coil” of the present invention.
The “inverter circuit 12” in the first embodiment corresponds to the “first high frequency power supply unit” of the present invention.
The “inverter circuit 62” in the first embodiment corresponds to the “second high-frequency power supply unit” of the present invention.
The “input current detection circuit 10” in the first embodiment corresponds to the “first coil current detection unit” of the present invention.
The “input current detection circuit 60” in the first embodiment corresponds to the “second coil current detection unit” of the present invention.
The “input current detection circuit 10” and the “control circuit 13” in the first embodiment correspond to the “first power detection unit” of the present invention.
The “input current detection circuit 60” and the “control circuit 13” in the first embodiment correspond to the “second power detection unit” of the present invention.
The “control circuit 13” in the first embodiment corresponds to the “control unit” of the present invention.

Based on the above, the operation of the induction heating cooker of the first embodiment will be described.
First, it is assumed that the pan is placed on the right heating port 2 by the user, the set heating power is set by the operation / display unit 8, and the start of heating is instructed.

  When the start of heating is instructed, the control circuit 13 performs a load determination process.

  FIG. 6 is a characteristic chart for determining the pan load based on the relationship between the input power and the current value of the heating coil in the induction cooking device according to the first embodiment. As shown in FIG. 6, the relationship between the input power and the heating coil current differs depending on the material of the pan load placed on the top plate 1. The control circuit 13 of the induction heating cooker according to the first embodiment stores therein a load determination table in which the relationship between the input power and the heating coil current shown in FIG. 6 is tabulated.

  In the load determination process, the control circuit 13 drives the inverter circuit 12 and the inverter circuit 62 with a specific drive signal for load determination, reads the output signals of the input current detection circuit 10 and the input current detection circuit 60, and inputs the input current value. And the input power to each of the inverter circuit 12 and the inverter circuit 62 is calculated from the integration of the input current value and the commercial power supply voltage. In addition, the control circuit 13 reads the output signals of the coil current detection circuit 15 and the coil current detection circuit 65 and detects the heating coil current flowing in each of the main coil 51 and the auxiliary coil 52. Then, the control circuit 13 refers to the load determination table representing the relationship of FIG. 6, and from the mapping state of the calculated input power and the read value of the heating coil current, the pan material placed on the main coil 51, The pan material placed on the auxiliary coil 52 is detected.

  FIG. 7 is a diagram illustrating combinations of detection results of pot material in the load determination process of the induction heating cooker according to Embodiment 1. Some pans have a size smaller than the outer diameter of the main coil 51, for example. Here, the pan is described as having a size straddling the main coil 51 and the auxiliary coil 52.

As described above, the material of the pan serving as a heating load is roughly classified into a magnetic material, a high resistance nonmagnetic material, and a low resistance nonmagnetic material.
When a magnetic pan is placed on the right heating port 2, the load determination results in the main coil 51 and the auxiliary coil 52 are both magnetic pans (case 1).
When the high resistance nonmagnetic pan is placed on the right heating port 2, the load determination results in the main coil 51 and the auxiliary coil 52 are both high resistance nonmagnetic pans (case 2).
When the low resistance nonmagnetic pan is placed in the right heating port 2, the load determination results in the main coil 51 and the auxiliary coil 52 are both low resistance nonmagnetic pans (case 3).
When no pan is placed on the right heating port 2, the load determination results in the main coil 51 and the auxiliary coil 52 are both unloaded (case 4).

  In recent years, there are many pans (sticking pans) in which magnetic stainless steel is bonded to the bottom of a pan of low resistance nonmagnetic material such as aluminum. When such a pasting pan is placed in the heating port, the load determination results in the main coil 51 and the auxiliary coil 52 are different, the load determination result in the main coil 51 is a magnetic pan, and the load in the auxiliary coil 52 The determination result is a high resistance non-magnetic pan (Case 5).

Hereinafter, the load determination when the pasting pan is placed will be described in detail.
8A and 8B are diagrams illustrating a configuration example of the pasting pan, FIG. 8A is a schematic cross-sectional view of the pasting pan, and FIG. 8B is a bottom view of the pasting pan. As illustrated in FIG. 8, the pasting pan 80 is configured, for example, by attaching a disk-shaped magnetic stainless steel plate 81 that is easily induction-heated to the outer surface of the center of the bottom surface of an aluminum material container 82 with high thermal conductivity. Has been. In the pasting pan 80 shown in FIG. 8, the magnetic stainless steel plate 81 is pasted only on the bottom surface (mounting surface) of the container 82.

  FIG. 9 is a diagram illustrating a state in which a pasting pan is placed on the right heating port of the induction heating cooker according to the first embodiment. As shown in FIG. 9, the main coil 51 and the auxiliary coil 52 are supported by the support base 26 below the top plate 1. When the pasting pan 80 is placed on the top plate 1 corresponding to the right heating port 2, depending on the size of the pasting pan 80 itself and the size of the magnetic stainless steel plate 81, A magnetic stainless steel plate 81 is placed, and a part of the magnetic stainless steel plate 81 and an aluminum container 82 are placed immediately above the auxiliary coil 52.

  As shown in FIG. 9, when the load determination on the auxiliary coil 52 is performed in the state where the magnetic stainless steel plate 81 and the aluminum container 82 are placed immediately above the auxiliary coil 52, the load determination result is Apparently, it exhibits characteristics close to those of a high-resistance nonmagnetic material. For this reason, when the pasting pan 80 is placed on the heating port, the load determination result in the main coil 51 becomes a magnetic pan, as shown in the case 5 of FIG. Become a magnetic pot.

The load determination process has been described above.
After performing the load determination process as described above, the control circuit 13 drives and controls each unit based on the load determination result.

  When the load determination result is case 3 (low resistance non-magnetic pan), the induction heating cooker according to the first embodiment cannot be heated, so that it cannot be heated using the operation / display unit 8. Inform the user to change the pan.

  Even when the load determination result is Case 4 (no load), the operation / display unit 8 notifies the user that heating is impossible, and prompts the user to place the pan.

  When the load determination result is case 1 (magnetic pan) or case 2 (high resistance non-magnetic pan), these pans are made of a material that can be heated by the induction heating cooker according to the first embodiment. 13 drives the inverter circuit 12 and the inverter circuit 62 to start heating the pot.

  FIG. 10 is a diagram illustrating the relationship between the set heating power and the input power when induction heating is performed on a magnetic pan or a high-resistance non-magnetic pan in the induction heating cooker according to the first embodiment. 10, reference numeral 100 is a line indicating the inverter circuit 12 of the main coil 51, reference numeral 101 is a line indicating the inverter circuit 62 of the auxiliary coil 52, and reference numeral 102 is the total input power of the inverter circuit 12 and the inverter circuit 62. It is a line which shows.

  When the load determination results in the main coil 51 and the auxiliary coil 52 are the same as in the case 1 and the case 2 shown in FIG. 7, the control circuit 13 includes the inverter circuit 12 and the inverter circuit 62 shown in FIG. 10. The inverter circuit 12 and the inverter circuit 62 are driven and controlled so that the total input power becomes the input power corresponding to the target power provided for each set thermal power. More specifically, as shown in FIG. 4, by changing the energization ratio of the high-potential-side IGBT (IGBT 24, IGBT 74) in a state where the frequency is constant, the input power according to the energization ratio is obtained. At this time, as shown in FIG. 10, power control is performed so that the input power of the inverter circuit 12 of the main coil 51 and the input power of the inverter circuit 62 of the auxiliary coil 52 are equal. By doing in this way, since the heating amount with respect to the pan from the main coil 51 and the auxiliary coil 52 becomes substantially equal, the pan can be heated uniformly in the radial direction. In this case, since the inverter circuit 12 and the inverter circuit 62 both heat the same material, the circuit loss of both is equal (see FIG. 5).

Next, drive control of the inverter circuit when the load determination result is case 5 (sticking pan) will be described.
FIG. 11 is a diagram showing the relationship between the set heating power and the input power when the pasting pan is induction-heated in the induction heating cooker according to the first embodiment. In FIG. 11, similarly to FIG. 10 described above, reference numeral 100 indicates a line indicating the inverter circuit 12 of the main coil 51, reference numeral 101 indicates a line indicating the inverter circuit 62 of the auxiliary coil 52, and reference numeral 102 indicates the inverter circuit 12. It is a line which shows the sum total of the input power of the inverter circuit 62. FIG.
When the control circuit 13 detects that a magnetic material is placed on the main coil 51 and a high-resistance non-magnetic material is placed on the auxiliary coil 52, as in the case 5 shown in FIG. It determines with having been carried out, and energization control of each coil is carried out by the relationship between the input electric power and setting heat power which are shown in FIG. This will be specifically described below.

First, for the inverter circuit 62 of the auxiliary coil 52, a threshold value Pa is set for the input power when the sticking pan is placed. This threshold value Pa is a preset input power value in a range in which the circuit loss when the inverter circuit 62 is driven in a state where the high-resistance nonmagnetic material is placed does not exceed the allowable loss of the inverter circuit 62. .
The control circuit 13 is connected to the inverter so that the sum of the input power of the inverter circuit 12 of the main coil 51 and the input power of the inverter circuit 62 of the auxiliary coil 52 becomes the input power corresponding to the target power provided for each set thermal power. The point of performing energization control of the circuit 12 and the inverter circuit 62 is the same as the case where a magnetic pan or a high-resistance nonmagnetic pan is placed. However, when the pasting pan is placed, the distribution of input power to the inverter circuit 12 and the inverter circuit 62 is different.

  First, in a range where the input power of the inverter circuit 62 does not exceed the threshold value Pa, the control circuit 13 is energized so that the input power of the inverter circuit 12 and the input power of the inverter circuit 62 are equal, as in FIG. The uniform control mode to be controlled is executed.

  On the other hand, when the energization control is performed so that the input powers of the inverter circuit 12 and the inverter circuit 62 are equal, the input power of the inverter circuit 62 is fixed to the threshold value Pa in a range where the input power of the inverter circuit 62 is equal to or higher than the threshold value Pa. By increasing the ratio of the input power of the inverter circuit 12, the input power is set according to the set thermal power. In other words, the set thermal power value when the total input power at the right heating port 2 (line indicated by reference numeral 102 in FIG. 11) is 2 × Pa is set as the set thermal power threshold Ta, and the operation / display is performed. When the value exceeding the set thermal power threshold Ta is set by the unit 8, the input power of the inverter circuit 62 of the auxiliary coil 52 is set as the threshold Pa, and the ratio of the input power to the inverter circuit 12 of the main coil 51 is given priority. Make it bigger. The control mode in which energization control is performed so that the ratio of the input power of the main coil 51 to the inverter circuit 12 is increased preferentially corresponds to the first heating coil priority mode of the present invention. In the first heating coil priority mode, the input power to the inverter circuit 62 of the auxiliary coil 52 is suppressed to the threshold value Pa, and the input power of the inverter circuit 12 of the main coil 51 is relatively increased, so that the input of both inverter circuits The slope of the total power line (reference numeral 102 in FIG. 11) is set to be the same as the inclination of the total input power line (reference numeral 102 in FIG. 10) shown in FIG.

  By doing in this way, while making the circuit loss of the auxiliary coil 52 which heats the part which has the characteristic similar to a high resistance nonmagnetic pan not exceed an allowable loss, it is set to a set thermal power as a total with respect to a sticking pan. Corresponding input power can be input.

  As described above, according to the first embodiment, the material of the heating load placed on the main coil and the auxiliary coil arranged concentrically is based on the output power of the high frequency power supply unit and the current flowing in each coil. When the pasting pan is detected, the first heating coil priority mode for energization control is executed so that the output power of the inverter circuit that drives the main coil is preferentially increased. . In the first heating coil priority mode, the target set thermal power can be obtained by preferentially increasing the output power of the inverter circuit driving the main coil with respect to the output power of the inverter circuit driving the auxiliary coil. I made it. For this reason, when heating a sticking pan, the output electric power as the whole heating port is not restrict | limited, and a sticking pan can be heated with the maximum output electric power with respect to setting heat power.

In addition, in the case where the pasting pan is induction-heated, the output power of the inverter circuit of the main coil and the output power of the inverter circuit of the auxiliary coil are evenly distributed so long as the output power of the inverter circuit of the auxiliary coil does not exceed the threshold value Pa. Energization control was performed so that For this reason, a sticking pan can be heated uniformly in a radial direction.
In addition, in the case where the pasting pan is induction-heated, if the output power of the inverter circuit of the main coil and the output power of the inverter circuit of the auxiliary coil are equalized, the output power of the inverter circuit of the auxiliary coil is within a range that is equal to or higher than the threshold value Pa Only the first heating coil priority mode was controlled. For this reason, when the set thermal power is relatively small, uniform heating of the pan is realized, and even when the set thermal power is relatively large, the output power of the entire heating port is limited due to the circuit loss of the inverter heating. A user-friendly induction heating cooker can be obtained.

  In addition, when it is detected that a pan of the same material is placed on the main coil and the auxiliary coil, the output power of the inverter circuit that drives the main coil and the output power of the inverter that drives the auxiliary coil are equal. Since it controls so that it may become, a pan can be heated uniformly in radial direction.

Embodiment 2. FIG.
In the first embodiment described above, when the load determination process performed in response to the instruction to start heating is different in the load determination results in the main coil and the auxiliary coil (case 5), the output power of the inverter circuit that drives the auxiliary coil On the other hand, the example which performs the 1st heating coil priority mode which raises the output power of the inverter circuit which drives a main coil preferentially was shown.
On the other hand, in this Embodiment 2, when the selection means which can choose to use a sticking pan as a to-be-heated object is provided and it is chosen to use a sticking pan as a to-be-heated object, An example in which the heating coil priority mode is executed will be described.
In the second embodiment, differences from the first embodiment will be mainly described, and the same components as those in the first embodiment are denoted by the same reference numerals.

  The operation / display unit 8 of the second embodiment is provided with a pasting pan selection unit (not shown) for the user to select whether or not to use the pasting pan as the object to be heated. . A pasting pan selection part will not ask | require a specific structure if it is an input device, such as a button and operation which can select the presence or absence of use of a pasting pan. An output signal from the pasting pan selection unit is input to the control circuit 13.

Next, operation | movement of the induction heating cooking appliance of Embodiment 2 is demonstrated.
First, it is assumed that the pan is placed on the right heating port 2 by the user, the set heating power is set by the operation / display unit 8, and the start of heating is instructed. Furthermore, in this Embodiment 2, it is possible to select whether or not to use the pasting pan by using the pasting pan selection unit (not shown) of the operation / display unit 8, and the user selects whether or not to use it. Is done.

  When it is selected that the pasting pan is not used in the pasting pan selection unit (not shown) of the operation / display unit 8, the control circuit 13 performs the same operation as in the first embodiment. . That is, when the start of heating is instructed, the control circuit 13 performs load determination processing and performs control based on the result of the load determination processing.

  On the other hand, when the use of the pasting pan is selected by the pasting pan selection unit (not shown) of the operation / display unit 8, the control circuit 13 performs the load determination process without performing the load determination process. The inverter circuit 12 and the inverter circuit 62 are driven and controlled in the same manner as when the case 5 (sticking pan) is determined in the load determination process in the first embodiment.

That is, when the use of the pasting pan is selected by the pasting pan selection unit, the output power of the inverter circuit 12 that drives the main coil 51 with respect to the output power of the inverter circuit 62 that drives the auxiliary coil 52. Is preferentially raised to execute the first heating coil priority mode for obtaining the target set thermal power.
In addition, when the use of the pasting pan is selected by the pasting pan selection unit, the output power of the inverter circuit 62 of the auxiliary coil 52 does not exceed the threshold value Pa. The energization control is performed so that the output power is equal to the output power of the inverter circuit 62 of the auxiliary coil 52.
In addition, when the use of the pasting pan is selected by the pasting pan selection unit, the output power of the inverter circuit 12 of the main coil 51 and the output power of the inverter circuit 62 of the auxiliary coil 52 are equalized to assist. Control is performed in the first heating coil priority mode only in a range where the output power of the inverter circuit 62 of the coil 52 is equal to or greater than the threshold value Pa.

  For this reason, according to the second embodiment, the same effect as in the first embodiment can be obtained. Moreover, in this Embodiment 2, since the sticking pan selection part for selecting using a sticking pan as a to-be-heated object was provided, when using the sticking pan is selected, Without performing the load determination process, heating of the pasting pan can be started quickly. Further, when the use of the pasting pan is selected, the load determination process is not performed, so that it is possible to quickly return the thermal power when the pan is shaken.

Embodiment 3 FIG.
In the third embodiment, among the components of the inverter circuit that drives the auxiliary coil 52, the switching element is configured using an element formed of a wide band gap semiconductor such as silicon carbide, a gallium nitride-based material, or diamond. The case will be described.

The third embodiment is different from the first embodiment in that the switching elements (IGBT 74 and IGBT 75) constituting the inverter circuit 62 for supplying a high frequency current to the auxiliary coil 52 are made of silicon carbide, gallium nitride-based material, diamond, or the like. This is a point formed by an element formed of a semiconductor (hereinafter sometimes simply referred to as a wide band gap semiconductor).
Note that the switching elements (IGBT 24 and IGBT 25) constituting the inverter circuit 12 that drives the main coil 51 are semiconductors made of a silicon-based material.

FIG. 12 is a diagram for explaining the relationship between input power and inverter circuit loss in the case of induction heating a high-resistance nonmagnetic pan in the induction heating cooker according to Embodiment 3.
In FIG. 12, reference numeral 41 is a line indicating the input power and circuit loss of an inverter circuit configured with a silicon-based semiconductor switching element, and reference numeral 42 is an input power of an inverter circuit configured with a wide bandgap semiconductor switching element. And a line indicating circuit loss. Reference numeral 43 denotes a line indicating the allowable loss of the inverter circuit constituted by a silicon-based semiconductor switching element, and reference numeral 44 denotes a line indicating the allowable loss of the inverter circuit constituted by a wide band gap semiconductor switching element.

  In general, a switching element or a diode element formed of a wide band gap semiconductor has a higher withstand voltage and a higher allowable current density than a silicon-based semiconductor, so that the loss of the element can be reduced. Therefore, the slope of the line 42 indicating the loss of the inverter circuit configured with the switching element of the wide band gap semiconductor is smaller than the slope of the line 41 indicating the loss of the inverter circuit configured with the switching element of the silicon-based semiconductor. .

  In addition, since the switching element and the diode element formed by the wide band gap semiconductor have high heat resistance, the value of the allowable loss can be increased when the cooling conditions determined by the heat radiating fins and the cooling fan are the same. Therefore, as shown in FIG. 12, the permissible loss (reference numeral 44) of the inverter circuit composed of wide bandgap semiconductor switching elements is the permissible loss (reference numeral 43) of the inverter circuit composed of silicon-based semiconductor switching elements. It is set to a large value compared with.

  From the above, when the switching element of the inverter circuit 62 of the auxiliary coil 52 is formed of a wide band gap semiconductor, the upper limit value of input power that can be input when a high-resistance nonmagnetic material is placed on the auxiliary coil 52, The switching element can be made larger than the case where it is composed of a silicon-based semiconductor. That is, in FIG. 11 of the first embodiment, when the pasting pan is placed, the input power of the inverter circuit 62 of the auxiliary coil 52 is described as having the threshold Pa as the upper limit. By configuring the switching element of the inverter circuit 62 with a wide band gap semiconductor as in the third embodiment, the upper limit value of the input power of the inverter circuit 62 can be set to a threshold value Pb that is a value larger than the threshold value Pa.

FIG. 13 is a diagram showing the relationship between the set thermal power and the input power when the pasting pan is induction-heated in the induction heating cooker according to the third embodiment. For comparison with the first embodiment, FIG. 13 shows the threshold Pa and the set thermal power threshold Ta shown in FIG. 11 together.
As shown in FIG. 13, the threshold value Pb, which is the upper limit value of the input power of the inverter circuit 62 that drives the auxiliary coil 52 of the third embodiment, is larger than the value (threshold value Pa) shown in the first embodiment. It can be. For this reason, the threshold value Tb of the set thermal power in the third embodiment can be set to a value larger than the threshold value Ta of the set thermal power in the first embodiment. That is, the range of the set thermal power that can control the input power of the inverter circuit of the main coil 51 and the auxiliary coil 52 evenly can be expanded.

  As described above, in the third embodiment, the switching element provided in the inverter circuit that drives the auxiliary coil is formed of a wide band gap semiconductor such as silicon carbide, a gallium nitride material, or diamond. For this reason, when heating the pasting pan, compared with the case where an element formed of a silicon-based semiconductor is used as a switching element of the inverter circuit that drives the auxiliary coil, the pan is heated to a larger set thermal power range. Uniform heating is possible.

  In the third embodiment, the switching element of the inverter circuit that drives the auxiliary coil is configured with a wide band gap semiconductor. However, the switching element of the inverter circuit that drives the main coil is also configured with a wide band gap semiconductor. It may be configured.

  Moreover, in the said description, although the example which applied the structure which concerns on this invention only to one (right heating port 2) of the several heating port of an induction heating cooking appliance was shown, of course, to a some heating port On the other hand, the configuration according to the present invention may be applied.

  Moreover, although the example which provided the auxiliary coil concentrically with the main coil was shown in the said description, it may replace with such an auxiliary coil and may arrange | position a some auxiliary coil cyclically | annularly on the outer periphery of a main coil. In this case, the operation of the plurality of auxiliary coils as a whole is the same as that of the auxiliary coils in the first and second embodiments.

  1 top plate, 2 right heating port, 3 left heating port, 4 central heating port, 5 heating coil, 6 heating coil, 8 operation / display unit, 9 commercial power supply, 10 input current detection circuit, 11 DC power supply circuit, 12 inverter Circuit, 13 control circuit, 14 snubber capacitor, 15 coil current detection circuit, 16 resonance capacitor, 17 clamp diode, 18 load circuit, 21 diode bridge, 22 choke coil, 23 smoothing capacitor, 24 IGBT, 25 IGBT, 26 support base, 30 circuit, 31 circuit, 51 main coil, 52 auxiliary coil, 60 input current detection circuit, 61 DC power supply circuit, 62 inverter circuit, 64 snubber capacitor, 65 coil current detection circuit, 66 resonance capacitor, 67 clamp diode, 68 load circuit , 71 Dio Doburijji, 72 choke coil, 73 a smoothing capacitor, 74 IGBT, 75 IGBT, 80 pots, 81 magnetic stainless steel plate, 82 the container.

Claims (9)

A first heating coil;
A second heating coil disposed on the outer peripheral side of the first heating coil;
A first high frequency power supply for supplying an alternating current to the first heating coil;
A second high-frequency power supply for supplying an alternating current to the second heating coil;
A first coil current detector for detecting a current flowing in the first heating coil;
A second coil current detector for detecting a current flowing in the second heating coil;
A first power detection unit that detects output power of the first high-frequency power supply unit;
A second power detection unit that detects output power of the second high-frequency power supply unit;
A control unit for controlling the first high-frequency power supply unit and the second high-frequency power supply unit so that the total output power from the first heating coil and the second heating coil becomes a power corresponding to a set heating power. ,
The controller is
From the detection results of the first power detection unit and the first coil current detection unit and the detection results of the second power detection unit and the second coil current detection unit, respectively, they are placed on the first heating coil. Detecting the material of the heating load and the heating load placed on the second heating coil,
When the heating load on the first heating coil and the heating load on the second heating coil are different, the output power of the first high frequency power supply unit is larger than the output power of the second high frequency power supply unit. An induction heating cooker having a first heating coil priority mode to be controlled. The controller is
When the heating load on the first heating coil and the heating load on the second heating coil are different,
In a range where the output power of the second high-frequency power supply unit does not exceed the threshold value, the output power of the first high-frequency power supply unit and the output power of the second high-frequency power supply unit are equalized according to the set thermal power. Control
When the output power of the second high frequency power supply unit is equal to or greater than the threshold when the output power of the first high frequency power supply unit and the output power of the second high frequency power supply unit are equalized, the first heating coil priority mode The induction heating cooker according to claim 1, wherein the induction heating cooker is controlled by: When the heating load on the first heating coil and the heating load on the second heating coil are different,
The induction heating cooking according to claim 1 or 2, wherein the heating load on the first heating coil is a magnetic material and the heating load on the second heating coil is a non-magnetic material. vessel. A first heating coil;
A second heating coil disposed on the outer peripheral side of the first heating coil;
A first high frequency power supply for supplying an alternating current to the first heating coil;
A second high-frequency power supply for supplying an alternating current to the second heating coil;
A selection means for selecting to use a sticking pan as a heating load;
A control unit for controlling the first high-frequency power supply unit and the second high-frequency power supply unit so that the total output power from the first heating coil and the second heating coil becomes a power corresponding to a set heating power. ,
The controller is
When it is selected by the selection means that the pasting pan is used as the object to be heated, the output power of the first high frequency power supply unit is controlled to be larger than the output power of the second high frequency power supply unit. An induction heating cooker having a first heating coil priority mode. The controller is
In the first heating coil priority mode,
The induction according to any one of claims 1 to 4, wherein the output power of the first high-frequency power supply unit is controlled in a state where the output power of the second high-frequency power supply unit is the threshold value. Cooking cooker. The controller is
When it is detected that the material of the heating load on the first heating coil and the material of the heating load on the second heating coil are the same,
The induction heating according to any one of claims 1 to 5, wherein the output power of the first high frequency power supply unit and the output power of the second high frequency power supply unit are controlled to be equal. Cooking device. The second heating coil is
The induction heating cooker according to any one of claims 1 to 6, wherein the induction heating cooker is provided substantially concentrically with the first heating coil so as to surround an outer periphery of the first heating coil. The induction heating cooker according to any one of claims 1 to 7, wherein the switching element provided in the second high-frequency power supply unit is formed of a wide band gap semiconductor. The induction heating cooker according to claim 8, wherein the wide band gap semiconductor is silicon carbide, a gallium nitride-based material, or diamond.

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