JP2005267996A - Induction heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce voltage duty impressed on the switching means and electric duty of the inverter constituent component. <P>SOLUTION: By a pot type judgement means 12, the drive frequency of the inverter circuit can be switched over depending on the material of the heated object 7, especially the voltage duty impressed on the switching means 5 and the electric duty of the inverter constituent component, and interference noise of the heated object 7 can be reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an induction heating apparatus used in general homes, restaurants, offices, factories and the like.

The conventional induction heating device is operated at a constant driving frequency regardless of the object to be heated. When the voltage duty of the switching means is large, the input power is lowered and the electrical duty of the switching means or the inverter circuit components The electric duty was reduced (for example, refer to Patent Document 1).
JP-A 63-128581

  However, in the above conventional configuration, since it can only be operated at a constant drive frequency regardless of the object to be heated, when the object to be heated is heated such that the voltage of the switching means becomes large, the input power must be lowered. As a result, the user's feeling of firepower was reduced.

  The present invention solves the above-mentioned problems. The drive frequency of the inverter circuit described above is optimized for the object to be heated, and the reduction in thermal power is suppressed for the user by obtaining the maximum input power. Another object of the present invention is to provide an induction heating device that reduces the electric duty of the switching means or the electric duty of the inverter circuit components.

  In order to achieve the above object, an induction heating apparatus according to the present invention includes a plurality of heating coils, and an inverter circuit that is provided in each of the heating coils and that induction-heats an object to be heated by supplying high-frequency current to the heating coils. Input current detection means for detecting the input current of the inverter circuit, switching voltage detection means for detecting the voltage of the switching means for switching the current of the resonance circuit of the inverter circuit, and control means for controlling the operation of the inverter circuit And the control means includes a pot type determination means for determining the material of the object to be heated from the information of the input current detection means and the switching voltage detection means, and the drive means of the drive means according to the signal of the pot type determination means The driving frequency is switched, and when the heating coil is operated first, it is input to the object to be heated. The power is heated at a certain driving frequency to obtain the optimum maximum power, and when the heating coil is operated at the second and subsequent times with multiple simultaneous heating, the driving frequency at which the second and subsequent operations are operated first. It is intended to match.

  As a result, the maximum input power is obtained regardless of the object to be heated, thereby suppressing the reduction of thermal power for the user and reducing the electrical responsibility for the switching means or the inverter circuit components. It is possible to suppress the squealing that occurs due to the difference between the driving frequencies of the plurality of coils.

  As described above, the present invention optimizes the drive frequency of the inverter circuit for the object to be heated and obtains the maximum input power to suppress the reduction of the thermal feeling for the user and to the switching means. However, it is possible to suppress the squealing that occurs due to the difference in the driving frequency of the plurality of coils while reducing the electrical duty or the electrical duty of the inverter circuit components.

  The first invention is a plurality of heating coils, an inverter circuit that is provided in each of the heating coils and supplies a high-frequency current to the heating coils to inductively heat an object to be heated, and detects an input current of the inverter circuit Input current detection means, switching voltage detection means for detecting the voltage of the switching means for switching the current of the resonance circuit of the inverter circuit, and control means for controlling the operation of the inverter circuit, the control means, It has a pan type determining means for determining the material of the heated object from the information of the input current detecting means and the switching voltage detecting means, and is configured to switch the driving frequency of the driving means by a signal of the pot type determining means. When the heating coil is operated, the power input to the object to be heated is a certain constant to obtain the optimum maximum power. Heating is performed at a dynamic frequency, and at the time of the second and subsequent heating coil operations by multiple simultaneous heating, the one operated after the second is configured to match the driving frequency operated at the first. . Thereby, the electrical duty of a switching means or the electrical duty of an inverter circuit component can be reduced, and the pot sound which generate | occur | produces by the difference in the drive frequency of several coils can be suppressed.

  In the second invention, particularly when the operation of the first heating coil of the first invention is finished and the second heating coil is different from the optimum driving frequency, the driving frequency is switched and the third heating coil is operated. Subsequent heating coils are also configured to operate in the order of use in order to match the driving frequency of the second heating coil. As a result, the electric duty of the switching means or the electric duty of the inverter circuit components can be reduced, and the reduction of the thermal feeling is suppressed for the user, and the squealing caused by the difference in driving frequency is suppressed. Can be suppressed.

  In the third invention, particularly when the operation of the first heating coil of the first invention causes the voltage duty of the switching means to increase due to the object to be heated and the driving frequency is switched, the driving frequency of the other heating coil is changed to the driving frequency. Are combined. As a result, the electric duty of the switching means or the electric duty of the inverter circuit components can be reduced, and the reduction of the thermal feeling is suppressed for the user, and the squealing caused by the difference in driving frequency is suppressed. Can be suppressed.

  According to a fourth aspect of the present invention, the switching of the drive frequency of the inverter circuit is gradually performed while operating. As a result, the electric duty of the switching means or the electric duty of the inverter circuit components can be reduced, and the reduction of the thermal feeling is suppressed for the user, and the squealing caused by the difference in driving frequency is suppressed. Can be suppressed.

  According to a fifth aspect of the present invention, the switching of the drive frequency of the inverter circuit according to the above-described invention is configured to stop once during operation and operate at a target drive frequency. As a result, the electric duty of the switching means or the electric duty of the inverter circuit components can be reduced, and the reduction of the thermal feeling is suppressed for the user, and the squealing caused by the difference in driving frequency is suppressed. Can be suppressed.

(Embodiment 1)
Embodiments of the present invention will be described below with reference to the drawings, taking an induction heating cooker as an example.

  FIG. 1 is a block diagram showing the configuration of the induction heating apparatus according to the first embodiment of the present invention, and FIG. 2 shows the signals and switching of the input current detecting means in the pot type determining means according to the first embodiment of the present invention. It is a graph which shows the relationship of the signal with a voltage detection means. In FIG. 1, 1 is an AC power source, 2 is a rectifier circuit comprising a bridge-connected diode that rectifies the AC power source, 3 is a smoothing circuit comprising a choke coil 3a and a capacitor 3b, 4 is an inverter circuit including switching means 5, 6 Is a heating coil that performs induction heating by applying a high-frequency alternating magnetic field to a heated object 7 such as a pan when supplied with a high-frequency current from the inverter circuit 4, and 8 is an input current detection means that detects the current flowing through the inverter circuit 4. , 9 is a switching voltage detecting means for detecting the voltage applied to the switching means 5 of the inverter circuit 4, the control means 10 is a driving means 11 for driving the switching means 5 for controlling the operation of the inverter circuit 4, and an input current detecting means 8; Pot type determination means 12 for determining the material of the heated object 7 based on the signal of the switching voltage detection means 9. The signal from the pan type determination unit 12 and a driving frequency switching means 13 for switching the driving frequency.

  In order to start induction heating, the drive means 11 of the control means 10 outputs a drive signal to the switching means 5, thereby operating the inverter circuit 4 and supplying a high-frequency current to the heating coil 6. By this high-frequency current, the object to be heated 7 such as a pan is induction-heated by the high-frequency magnetic flux generated from the heating coil 6. In order to determine the pot type, the voltage of the input current detecting means 8 and the switching means 5 for detecting the current flowing through the inverter circuit 4 as shown in FIG. Based on the signal from the switching voltage detection means for detecting the signal, it can be used normally in the part other than the shaded area in the figure, that is, in a region where the input current flows to some extent and the switching voltage is also to some extent, in other words, the switching voltage does not increase and is rated. Induction heating is started without being switched by the drive frequency switching means 13 as the heated body 7 to which electric power can be input. For example, when the object 7 to be heated is a magnetic stainless steel pan, it falls within the hatched area in FIG. That is, when the input voltage is small, the switching voltage is high. When induction heating is performed at the drive frequency as it is, the switching voltage becomes high, the voltage duty of the switching means 5 becomes large, and there is a possibility of destruction. In this case, the drive means switching means 13 operates to lower the drive frequency of the drive signal sent to the switching means 5 and lower the switching voltage, and performs control to obtain rated input power. .

  And it has a plurality of heating coils 6 and has a plurality of inverter circuits 4 for controlling each of the heating coils 6, and when a plurality of heating coils 6 are simultaneously heated, the interference sound of the heated object 7 is suppressed by driving at the same frequency. can do.

  When the heating coil 6 operated first is operated, the power input to the heated object 7 is heated at a certain driving frequency to obtain the optimum maximum power, and the second and subsequent heating coils are heated by a plurality of simultaneous heatings. At the time of 6 'operation, the one operated after the second is adjusted to the drive frequency operated first.

  When the operation of the first heating coil 6 is completed and the second heating coil 6 ′ is different from the optimum driving frequency, the driving frequency is switched, and the third and subsequent heating coils 6 ″ are also switched. In this configuration, priorities are set in order of use so as to match the driving frequency of the second heating coil 6 '. As a result, the electric duty of the switching means or the electric duty of the inverter circuit components can be reduced, and the reduction of the thermal feeling is suppressed for the user, and the squealing caused by the difference in driving frequency is suppressed. Can be suppressed.

  The switching of the driving frequency of the inverter circuit 4 is performed gradually while operating. Thereby, the electric duty of the switching means or the electric duty of the inverter circuit components can be reduced, and the deterioration of the thermal power feeling is suppressed for the user, and the difference is caused by the difference in driving frequency. Pottering can be suppressed.

  Further, the switching of the drive frequency of the inverter circuit 4 is configured to be stopped once during operation and operated at a target drive frequency. As a result, the electric duty of the switching means or the electric duty of the inverter circuit components can be reduced, and the reduction of the thermal feeling is suppressed for the user, and the squealing caused by the difference in driving frequency is suppressed. Can be suppressed.

  In addition, at the time of the first heating coil operation, the power input to the object to be heated is heated at a certain driving frequency to obtain the optimum maximum power, and at the time of the second and subsequent heating coil operations by a plurality of simultaneous heatings, When the voltage duty of the switching means is increased by the heated body and the driving frequency needs to be switched, the driving frequency of the other heating coil is adjusted to the driving frequency. As a result, the electric duty of the switching means or the electric duty of the inverter circuit components can be reduced, and the reduction of the thermal feeling is suppressed for the user, and the squealing caused by the difference in driving frequency is suppressed. Can be suppressed.

  Further, the switching of the drive frequency of the inverter circuit is performed gradually while being operated. As a result, the electric duty of the switching means or the electric duty of the inverter circuit components can be reduced, and the reduction of the thermal feeling is suppressed for the user, and the squealing caused by the difference in driving frequency is suppressed. Can be suppressed.

  In addition, switching of the drive frequency of the inverter circuit is configured to be stopped once during operation and operated at a target drive frequency. As a result, the electric duty of the switching means or the electric duty of the inverter circuit components can be reduced, and the reduction of the thermal feeling is suppressed for the user, and the squealing caused by the difference in driving frequency is suppressed. Can be suppressed.

  The induction heating device of the present invention switches the drive frequency of the inverter circuit according to the material of the object to be heated by the pan type determination means, particularly reduces the voltage duty on the switching means, and reduces the electrical duty of the inverter components, Since the interference sound of the heated object can be reduced, not only induction heating cookers and induction heating rice cookers that have already been put to practical use, but also electric water heaters, electric irons, dishwashers, water heaters, etc. that can be applied to induction heating The present invention can also be applied to uses of heating equipment, and can also be applied to other electrical equipment using an inverter circuit, a microwave oven, a refrigerator, a washing machine, and the like.

The block diagram of the induction heating apparatus in Embodiment 1 of this invention The graph which shows the relationship of the signal of the input current detection means and the signal of the switching voltage detection means in the pan seed | species determination means of the 1st Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectification circuit 3 Smoothing circuit 3a Choke coil 3b Capacitor 4 Inverter circuit 5 Switching means 6 Heating coil 7 Heated object 8 Input current detection means 9 Switching voltage detection means 10 Control means 11 Drive means 12 Pot type determination means 13 Drive Frequency switching means

Claims (5)

A plurality of heating coils, an inverter circuit that is provided in each of the heating coils and that inductively heats the object to be heated by supplying a high-frequency current to the heating coils, and an input current detection means that detects an input current of the inverter circuit; A switching voltage detecting means for detecting the voltage of the switching means for switching the current of the resonance circuit of the inverter circuit; and a control means for controlling the operation of the inverter circuit, the control means comprising a material of the object to be heated. The heating coil that has a pan type determination unit that is determined from information of the input current detection unit and the switching voltage detection unit and that switches the driving frequency of the driving unit according to a signal from the pan type determination unit, and that is operated first. During operation, the power input to the object to be heated is set to a certain drive frequency to obtain the optimum maximum power. Heated Te, in the heating time of coil operation of the second and subsequent in multiple simultaneous heating, induction heating apparatus that match the driving frequency of operating to a first towards operated at second and subsequent. The control means switches the driving frequency when the operation of the first heating coil is finished and the second heating coil is different from the optimum driving frequency, and the third and subsequent heating coils are also heated by the second heating coil. The induction heating apparatus according to claim 1, wherein the induction heating apparatus is configured to be operated with a priority in the order of use so as to match the driving frequency of the coil. The control means is configured to adjust the driving frequency of the other heating coil to the drive frequency when the voltage duty of the switching means becomes large due to the object to be heated in the first heating coil operation and the drive frequency is switched. The induction heating apparatus described. The induction heating apparatus according to any one of claims 1 to 3, wherein the control means is configured to gradually switch the drive frequency of the inverter circuit while operating the inverter circuit. The induction device according to any one of claims 1 to 3, wherein the control means is configured to temporarily switch the drive frequency of the inverter circuit when the inverter circuit is in operation and to operate the inverter circuit at a target drive frequency. Heating device.

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