WO2008078868A1 - Apparatus for controlling induction heating circuit - Google Patents

Apparatus for controlling induction heating circuit Download PDF

Info

Publication number
WO2008078868A1
WO2008078868A1 PCT/KR2007/003425 KR2007003425W WO2008078868A1 WO 2008078868 A1 WO2008078868 A1 WO 2008078868A1 KR 2007003425 W KR2007003425 W KR 2007003425W WO 2008078868 A1 WO2008078868 A1 WO 2008078868A1
Authority
WO
WIPO (PCT)
Prior art keywords
unit
controlling unit
output
input terminal
heating coil
Prior art date
Application number
PCT/KR2007/003425
Other languages
French (fr)
Inventor
Wang Jun Lee
Original Assignee
Woongjin Cuchen Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Woongjin Cuchen Co., Ltd. filed Critical Woongjin Cuchen Co., Ltd.
Publication of WO2008078868A1 publication Critical patent/WO2008078868A1/en

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/06—Control, e.g. of temperature, of power
    • H05B6/062—Control, e.g. of temperature, of power for cooking plates or the like
    • H05B6/065—Control, e.g. of temperature, of power for cooking plates or the like using coordinated control of multiple induction coils
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/06—Control, e.g. of temperature, of power
    • H05B6/062—Control, e.g. of temperature, of power for cooking plates or the like
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B1/00—Details of electric heating devices
    • H05B1/02—Automatic switching arrangements specially adapted to apparatus ; Control of heating devices
    • H05B1/0227—Applications
    • H05B1/0252—Domestic applications
    • H05B1/0258—For cooking
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/10—Induction heating apparatus, other than furnaces, for specific applications
    • H05B6/12—Cooking devices
    • H05B6/1209—Cooking devices induction cooking plates or the like and devices to be used in combination with them
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/36—Coil arrangements
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/36—Coil arrangements
    • H05B6/44—Coil arrangements having more than one coil or coil segment
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B40/00—Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers

Definitions

  • the present invention relates to an IH circuit control apparatus, and more particularly to an IH circuit control apparatus which controls two independent heating coils through one oscillation control circuit.
  • an induction heating (IH) apparatus refers to an apparatus for cooking food and the like by heating a magnetic vessel resting on a heating coil in such a manner that a commercial direct current voltage applied to the heating coil is switched on/off, and a strong magnetic field is formed in the heating coil through a counter electromotive force generated when the commercial direct current voltage is turned off.
  • a method for controlling the output of the induction heating apparatus is a method for controlling the output by using a phase detecting means for detecting a phase difference signal from both ends of a resonance circuit of the induction heating apparatus.
  • a trigger signal is supplied for keeping an oscillating means oscillating by synchronizing a resonance time constant with the oscillating timing of the oscillating means and using the phase difference signal detected from the phase detecting means.
  • Another method using a duty cycle is also used for controlling the output of the induction heating apparatus.
  • the controlling method using a duty cycle is a method for controlling the output by using a ratio between power-on time and power-off time of a rated maximum output. In this method, a low output is produced when the power is switched on for a short time and is switched off for a long time. On the contrary, a high output is produced when the power is switched on for a long time and is switched off for a short time. Disclosure of Invention
  • the present invention aims at providing an IH circuit control apparatus which controls two independent heating coils by using one oscillation control circuit.
  • the present invention has an advantage in that it reduces the manufacturing cost and the number of parts by controlling two independent heating coils by use of one control unit, so that manufacturing efficiency can be extraordinarily improved. [11] Also, the present invention has an effect of preventing noise from being caused by a frequency difference when heating coils are driven by means of two control circuits. [12] The present invention has also an effect of preventing a voltage induced in each heating coil from being superposed on a resonance voltage and thus preventing a resonance voltage waveform from being distorted.
  • FIG. 1 is a block diagram illustrating the structure of an induction heating apparatus having an IH circuit control apparatus according to the present invention
  • FIG. 2 is a block diagram illustrating the structure of an IH circuit according to the present invention
  • FIG. 3 is an electrical circuit diagram illustrating the IH circuit of FIG. 2 in detail
  • An IH circuit control apparatus includes a first
  • IGBT driving unit outputting a control signal for switching on/off a first heating coil unit which heats a cooking vessel with a certain output according to a switching signal; a second IGBT driving unit outputting a control signal for switching on/off a second heating coil unit which heats the cooking vessel; a microprocessor outputting control signals for switching on/off the first IGBT driving unit and the second IGBT driving unit, and outputting an oscillation signal for switching control of the first IGBT driving unit and the second IGBT driving unit; an IH controlling unit simultaneously outputting switching on/off signals for the first IGBT driving unit and the second IGBT driving unit according to the oscillation signal output from the microprocessor; and an output compensating unit outputting a compensating signal to the IH controlling unit according to a change value detected from at least one of a voltage change value and an output change value of an utility power supply so as to vary switching-on times of the first and the second heating coil units.
  • the IH controlling unit includes an on-time controlling unit outputting swithing-on signals for the first IGBT driving unit and the second IGBT driving unit so as to switch on the first heating coil unit and the second heating coil unit according to the oscillation signal output from the microprocessor; an off-time controlling unit outputting switching-off signals to the on-time controlling unit in such a manner that the on-time cntrolling unit switches off the first heating coil unit and the second heating coil unit; a feedback controlling unit controlling operations of the off-time controlling unit according to the switching on/off signals output from the on-time controlling unit; and a voltage follower circuit unit providing the on-time controlling unit with a reference voltage for determining an on-time duration of the on-time controlling unit, according to a compensation signal output from the output compensating unit.
  • the on-time controlling unit includes a resistance and a capacitor determining switching-on times of the first heating coil unit and the second heating coil unit; a comparator, in which signals input from the off-time controlling unit and from the voltage follower circuit unit are connected to a positive (+) input terminal thereof, the resistance and the capacitor are connected to a negative (-) input terminal thereof, and switching on/off operation control signals for the first IGBT driving unit and the second IGBT driving unit are output at an output terminal thereof, according to the signal input into the positive (+) input terminal thereof and the negative (-) input terminal thereof; and a diode maintaining a voltage difference between the positive (+) input terminal and the negative (-) input terminal of the comparator.
  • the feedback controlling unit includes a transistor, of which a base stage is connected to the output terminal of the on-time controlling unit through a resistance, and a collector stage is connected to the off-time controlling unit, and the transistor is switched on/off according to a signal output from the on-time controlling unit, resulting in on/off of the off-time controlling unit.
  • the base stage of the transistor further includes a diode for discharging a current remaining in the base stage of the transistor when the transistor is switched off.
  • the feedback controlling unit includes a comparator, where the output of the on- time controlling unit is connected to a negative (-) input terminal thereof, a reference voltage is connected to a positive (+) input terminal thereof, and an output terminal thereof is connected to the off-time controlling unit, and the comparator switches on/ off the off-time controlling unit according to the output signal of the on-time controlling unit, input to the negative (-) input terminal thereof.
  • the off-time controlling unit includes a resistance and a capacitor determining switching-off times of the first heating coil unit and the second heating coil unit; a comparator, in which the resistance and the capacitor are connected to a positive (+) input terminal thereof, a reference voltage is connected to a negative (-) input terminal thereof, and an off signal of the on-time controlling unit is output to the on-time controlling unit through an output terminal thereof, according to the time constants of the capacitor and the resistance of the positive (+) input terminal thereof; and a resistance, of which one side is connected to the feedback controlling unit, the other side is connected to the positive (+) input terminal of the comparator, which maintains that the voltage of the positive (+) input terminal of the comparator is higher than the voltage of the negative (-) input terminal of the comparator when a signal state of the feedback controlling unit is converted from a high-level state into a low-level state.
  • FIG. 1 illustrates a structure of an induction heating apparatus having an IH circuit control apparatus according to the present invention.
  • the IH circuit control apparatus includes a current detecting unit 120 using a direct current power supply into which a power supply applied from a utility power supply 100 is converted by a rectifying unit 110, and detecting an output current change value according to driving; a voltage detecting unit 130 detecting a voltage change value of an input power supply; an output compensating unit 140 outputting a control signal for output compensation according to the change values detected from the current detecting unit 120 and the voltage detecting unit 130; a first IGBT driving unit 300 outputting a control signal for switching on/off a first heating coil unit 500 which heats a cooking vessel (not shown) with a certain output according to a switching signal; a second IGBT driving unit 310 outputting a control signal for switching on/off a second heating coil unit 510 which heats the cooking vessel; a microprocessor 150 outputting an on/off signal Sl, S2 to the first IGBT driving unit 300 and the second IGBT driving unit 310, and outputting an oscillation signal Ml for
  • FIG. 2 illustrates a structure of an IH circuit according to the present invention
  • FIG. 3 illustrates in detail the IH circuit of FIG. 2.
  • the structure of the IH circuit control apparatus according to the present invention will be described in more detail with reference to FIG. 1 to FIG. 3.
  • the microprocessor 150 outputs an on/off signal Sl, S2 for each of the first and the second IGBT driving units 300, 310 which control on/off switching of two independent heating coils, that is, the first and the second heating coil units 500, 510, and an oscillation signal Ml for controlling on/off switching operations of the first and the second heating coils 500, 510, respectively in a state where the first and the second IGBT driving units 300 and 310 are in an on-state.
  • the microprocessor 150 applies the oscillation signal Ml to both the first and the second IGBT driving units 300 and 310, and outputs a signal Sl for controlling on/off of the first IGBT driving unit 300 and a signal S2 for controlling on/off of the second IGBT driving unit 310 to the first and the second IGBT driving units 300 and 310, respectively, so as to selectively operate the first and the second IGBT driving units 300 and 310 according to the oscillation signal M 1.
  • the IH controlling unit 200 outputs signals for controlling on/off of the first and the second IGBT driving units 300 and 310 such that the first and the second heating coil units 500 and 510 operate at the same operation frequency according to the oscillation signal Ml output from the microprocessor 150.
  • Such a structure of the IH controlling unit 200 includes an on-time controlling unit 210 outputting a switching on/off control signal for the first IGBT driving unit 300 to switch on the first heating coil unit 500, and outputting a switching on-off control signal for the second IGBT driving unit 310 to switch on the second heating coil unit 510 according to the oscillation signal Ml output from the microprocessor 150; an off- time controlling unit 230 controlling the on- time controlling unit 210 to output switching-off signals for the first heating coil unit 500 and the second heating coil unit 510; a feedback controlling unit 240 controlling operations of the off- time controlling unit 230 according to switching on/off control signals for the first heating coil unit 500 and the second heating coil unit 510, which are output from the on-time controlling unit 210; and a voltage follower circuit unit 250 providing the on-time controlling unit with a reference voltage, which determines an on-time duration of the on-time controlling unit 210, according to a compensation signal output from the output compensating unit 140.
  • the on-time controlling unit 210 includes a comparator 211, in which signals input from the off-time controlling unit 230 and from the voltage follower circuit unit 250 are connected to a positive (+) input terminal thereof, a resistance Rl and a capacitor Cl determining a switching-on time of the on-time controlling unit 210, that is, a time to switch on the first heating coil unit 500 and the second heating coil unit 510, are connected to a negative (-) input terminal thereof, and switching on/off control signals for the first IGBT driving unit 300 and the second IGBT driving unit 310 are output at an output terminal thereof connected to the first IGBT driving unit 300 and the second IGBT driving unit 310, according to the signal input into the positive (+) input terminal thereof; and a diode D3, which is provided between the positive (+) input terminal and the negative (-) input terminal of the comparator 211, and maintains a voltage difference between the positive (+) input terminal and the negative (-) input terminal.
  • the off- time controlling unit 230 includes a comparator 231 , in which a resistance
  • the resistance R6 and the capacitor C2 determining switching-off times of the first heating coil unit 500 and the second heating coil unit 510 are connected in series, the resistance R6 and the capacitor C2 are connected to a positive (+) input terminal thereof, a reference voltage is connected to a negative (-) input terminal thereof, and an off signal of the on-time controlling unit 210 is output to the on-time controlling unit 210 through an output terminal thereof according to the time constants of the capacitor C2 and the resistance R6 connected to the positive (+) input terminal thereof; and a resistance R9, of which one side is connected to the feedback controlling unit 240, the other side is connected to the positive (+) input terminal of the comparator 231, which maintains that the voltage of the positive (+) input terminal of the comparator 231 is higher than the voltage of the negative (-) input terminal of the comparator 231 when a signal state of the feedback controlling unit 240 is converted from a high-level state into a low-level state.
  • the feedback controlling unit 240 includes a transistor 241, of which a base stage is connected to the output terminal of the on-time controlling unit 210 through a resistance R5, and a collector stage is connected to the input terminal of the off-time controlling unit 230.
  • the transistor 241 is switched on/off according to a signal output from the output terminal of the on-time controlling unit 210, resulting in on/off of the off-time controlling unit 230.
  • the feedback controlling unit 240 may be configured in such a manner as to have a diode D8 for discharging a current remaining in the base stage of the transistor 241 when the transistor 241 is switched off.
  • the feedback controlling unit 240 may also be configured in such a manner as to have a comparator 242, in which the output of the on-time controlling unit 210 is connected and input to a negative (-) input terminal thereof, a reference voltage is connected to a positive (+) input terminal thereof, and an output terminal thereof is connected to the input terminal of the off-time controlling unit 230, so as to switch on/off the off-time controlling unit 230 according to the output signal of the on-time controlling unit 210, input to the negative (-) input terminal of the comparator 242.
  • the voltage follower circuit unit 250 receives at least one of the output compensation signal provided by the output compensating unit 140 and the oscillation signal Ml output from the microprocessor 150, and provides the received signal as a reference voltage for determining an on-time duration of the on-time controlling unit 210, so that a time during which the on-time controlling unit 210 maintains a switched- on state can vary according to voltage changes and output changes.
  • the voltage follower circuit unit 250 uses the well-known structure using an OP AMP 251.
  • the first IGBT driving unit 300 outputs a control signal for an IGBT element 400 in such a manner that the first heating coil unit 500 which heats a cooking vessel (not shown) with a certain output is switched on/off, according to a signal output from the on-time controlling unit 210.
  • the second IGBT driving unit 310 is connected in parallel to the first IGBT driving unit 300 and outputs a control signal for the IGBT element 410 in such a manner that the second heating coil unit 510 which heats the cooking vessel with a certain output is switched on/off the second heating coil unit 510 which heats the cooking vessel with a certain output, according to a signal output from the on-time controlling unit 210.
  • the present invention has advantages in that it can provide an induction heating apparatus having a high output by using a plurality of independent heating coils, reduce the manufacturing process and improve the production efficiency by simplifying a control circuit.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Induction Heating Cooking Devices (AREA)
  • General Induction Heating (AREA)

Abstract

Disclosed is an IH circuit control apparatus capable of providing a high output and a low output by controlling two or more independent heating coils through one control circuit.

Description

Description
APPARATUS FOR CONTROLLING INDUCTION HEATING
CIRCUIT
Technical Field
[1] The present invention relates to an IH circuit control apparatus, and more particularly to an IH circuit control apparatus which controls two independent heating coils through one oscillation control circuit. Background Art
[2] Generally, an induction heating (IH) apparatus refers to an apparatus for cooking food and the like by heating a magnetic vessel resting on a heating coil in such a manner that a commercial direct current voltage applied to the heating coil is switched on/off, and a strong magnetic field is formed in the heating coil through a counter electromotive force generated when the commercial direct current voltage is turned off.
[3] A method for controlling the output of the induction heating apparatus is a method for controlling the output by using a phase detecting means for detecting a phase difference signal from both ends of a resonance circuit of the induction heating apparatus. In this method, a trigger signal is supplied for keeping an oscillating means oscillating by synchronizing a resonance time constant with the oscillating timing of the oscillating means and using the phase difference signal detected from the phase detecting means.
[4] Another method using a duty cycle is also used for controlling the output of the induction heating apparatus. The controlling method using a duty cycle is a method for controlling the output by using a ratio between power-on time and power-off time of a rated maximum output. In this method, a low output is produced when the power is switched on for a short time and is switched off for a long time. On the contrary, a high output is produced when the power is switched on for a long time and is switched off for a short time. Disclosure of Invention
Technical Problem
[5] However, such an induction heating apparatus has a problem in that it cannot provide a high output due to limitations on the performance of an IGBT element.
[6] Although an IH circuit has recently been proposed, which is configured to provide a high output, which could not be provided by one heating coil, by means of two independent heating coils, there is a problem that a control circuit is enlarged because independent control circuits are required for separately controlling the two independent heating coils. [7] Also, when the heating coils are driven by using two control circuits, there is another problem in that a frequency difference between the two control circuits causes noise. [8] Additionally, the respective heating coils function as a transformer with a core formed by one and the same cooking vessel, and thus a voltage is induced between each other. The induced voltage is superposed on a resonance voltage, which causes a problem of the distortion of a resonance voltage waveform.
Technical Solution [9] In order to solve the above-mentioned problems, the present invention aims at providing an IH circuit control apparatus which controls two independent heating coils by using one oscillation control circuit.
Advantageous Effects
[10] The present invention has an advantage in that it reduces the manufacturing cost and the number of parts by controlling two independent heating coils by use of one control unit, so that manufacturing efficiency can be extraordinarily improved. [11] Also, the present invention has an effect of preventing noise from being caused by a frequency difference when heating coils are driven by means of two control circuits. [12] The present invention has also an effect of preventing a voltage induced in each heating coil from being superposed on a resonance voltage and thus preventing a resonance voltage waveform from being distorted.
Brief Description of the Drawings [13] FIG. 1 is a block diagram illustrating the structure of an induction heating apparatus having an IH circuit control apparatus according to the present invention; [14] FIG. 2 is a block diagram illustrating the structure of an IH circuit according to the present invention;
[15] FIG. 3 is an electrical circuit diagram illustrating the IH circuit of FIG. 2 in detail;
[16] FIG. 4 is an electrical circuit diagram illustrating another embodiment of a voltage follower circuit unit of FIG. 3; and [17] FIG. 5 is an electrical circuit diagram illustrating yet another embodiment of the voltage follower circuit unit of FIG. 3.
[18] (description of reference numerals on main parts of the drawings)
[19] 100 : utility power supply 110 : rectifying unit
[20] 120 : current detecting unit 130 : voltage detecting unit
[21] 140 : output compensating unit 150 : microprocessor
[22] 200 : IH controlling unit 210 : on-time controlling unit
[23] 230 : off-time controlling unit 240 : feedback controlling unit
[24] 250 : voltage follower circuit unit 300 : first IGBT driving unit [25] 310 : second IGBT driving unit 400 : first IGBT element
[26] 410 : second IGBT element 500 : first heating coil unit
[27] 510 : second heating coil unit
Best Mode for Carrying Out the Invention
[28] An IH circuit control apparatus according to the present invention includes a first
IGBT driving unit outputting a control signal for switching on/off a first heating coil unit which heats a cooking vessel with a certain output according to a switching signal; a second IGBT driving unit outputting a control signal for switching on/off a second heating coil unit which heats the cooking vessel; a microprocessor outputting control signals for switching on/off the first IGBT driving unit and the second IGBT driving unit, and outputting an oscillation signal for switching control of the first IGBT driving unit and the second IGBT driving unit; an IH controlling unit simultaneously outputting switching on/off signals for the first IGBT driving unit and the second IGBT driving unit according to the oscillation signal output from the microprocessor; and an output compensating unit outputting a compensating signal to the IH controlling unit according to a change value detected from at least one of a voltage change value and an output change value of an utility power supply so as to vary switching-on times of the first and the second heating coil units.
[29] Also, switching-off times of the first heating coil unit and the second heating coil unit are constant.
[30] The IH controlling unit includes an on-time controlling unit outputting swithing-on signals for the first IGBT driving unit and the second IGBT driving unit so as to switch on the first heating coil unit and the second heating coil unit according to the oscillation signal output from the microprocessor; an off-time controlling unit outputting switching-off signals to the on-time controlling unit in such a manner that the on-time cntrolling unit switches off the first heating coil unit and the second heating coil unit; a feedback controlling unit controlling operations of the off-time controlling unit according to the switching on/off signals output from the on-time controlling unit; and a voltage follower circuit unit providing the on-time controlling unit with a reference voltage for determining an on-time duration of the on-time controlling unit, according to a compensation signal output from the output compensating unit.
[31] The on-time controlling unit includes a resistance and a capacitor determining switching-on times of the first heating coil unit and the second heating coil unit; a comparator, in which signals input from the off-time controlling unit and from the voltage follower circuit unit are connected to a positive (+) input terminal thereof, the resistance and the capacitor are connected to a negative (-) input terminal thereof, and switching on/off operation control signals for the first IGBT driving unit and the second IGBT driving unit are output at an output terminal thereof, according to the signal input into the positive (+) input terminal thereof and the negative (-) input terminal thereof; and a diode maintaining a voltage difference between the positive (+) input terminal and the negative (-) input terminal of the comparator.
[32] The feedback controlling unit includes a transistor, of which a base stage is connected to the output terminal of the on-time controlling unit through a resistance, and a collector stage is connected to the off-time controlling unit, and the transistor is switched on/off according to a signal output from the on-time controlling unit, resulting in on/off of the off-time controlling unit.
[33] The base stage of the transistor further includes a diode for discharging a current remaining in the base stage of the transistor when the transistor is switched off.
[34] The feedback controlling unit includes a comparator, where the output of the on- time controlling unit is connected to a negative (-) input terminal thereof, a reference voltage is connected to a positive (+) input terminal thereof, and an output terminal thereof is connected to the off-time controlling unit, and the comparator switches on/ off the off-time controlling unit according to the output signal of the on-time controlling unit, input to the negative (-) input terminal thereof.
[35] The off-time controlling unit includes a resistance and a capacitor determining switching-off times of the first heating coil unit and the second heating coil unit; a comparator, in which the resistance and the capacitor are connected to a positive (+) input terminal thereof, a reference voltage is connected to a negative (-) input terminal thereof, and an off signal of the on-time controlling unit is output to the on-time controlling unit through an output terminal thereof, according to the time constants of the capacitor and the resistance of the positive (+) input terminal thereof; and a resistance, of which one side is connected to the feedback controlling unit, the other side is connected to the positive (+) input terminal of the comparator, which maintains that the voltage of the positive (+) input terminal of the comparator is higher than the voltage of the negative (-) input terminal of the comparator when a signal state of the feedback controlling unit is converted from a high-level state into a low-level state. Mode for the Invention
[36] Hereinafter, an exemplary embodiment according to the present invention will be described with reference to the accompanying drawings.
[37] FIG. 1 illustrates a structure of an induction heating apparatus having an IH circuit control apparatus according to the present invention.
[38] The IH circuit control apparatus according to the present invention includes a current detecting unit 120 using a direct current power supply into which a power supply applied from a utility power supply 100 is converted by a rectifying unit 110, and detecting an output current change value according to driving; a voltage detecting unit 130 detecting a voltage change value of an input power supply; an output compensating unit 140 outputting a control signal for output compensation according to the change values detected from the current detecting unit 120 and the voltage detecting unit 130; a first IGBT driving unit 300 outputting a control signal for switching on/off a first heating coil unit 500 which heats a cooking vessel (not shown) with a certain output according to a switching signal; a second IGBT driving unit 310 outputting a control signal for switching on/off a second heating coil unit 510 which heats the cooking vessel; a microprocessor 150 outputting an on/off signal Sl, S2 to the first IGBT driving unit 300 and the second IGBT driving unit 310, and outputting an oscillation signal Ml for switching control of the first and the second IGBT driving units 300 and 310; and an IH controlling unit 200 simultaneously outputting the switching on/off signals to the first and the second IGBT driving units 300 and 310 according to the oscillation signal Ml output from the microprocessor. Undescribed reference numerals 400 and 410 designate IGBT elements.
[39] FIG. 2 illustrates a structure of an IH circuit according to the present invention, and
FIG. 3 illustrates in detail the IH circuit of FIG. 2. The structure of the IH circuit control apparatus according to the present invention will be described in more detail with reference to FIG. 1 to FIG. 3.
[40] The microprocessor 150 outputs an on/off signal Sl, S2 for each of the first and the second IGBT driving units 300, 310 which control on/off switching of two independent heating coils, that is, the first and the second heating coil units 500, 510, and an oscillation signal Ml for controlling on/off switching operations of the first and the second heating coils 500, 510, respectively in a state where the first and the second IGBT driving units 300 and 310 are in an on-state.
[41] That is, when the first heating coil unit 500 and the second heating coil unit 510 operate at the same time or when only one of them operates, the microprocessor 150 applies the oscillation signal Ml to both the first and the second IGBT driving units 300 and 310, and outputs a signal Sl for controlling on/off of the first IGBT driving unit 300 and a signal S2 for controlling on/off of the second IGBT driving unit 310 to the first and the second IGBT driving units 300 and 310, respectively, so as to selectively operate the first and the second IGBT driving units 300 and 310 according to the oscillation signal M 1.
[42] The IH controlling unit 200 outputs signals for controlling on/off of the first and the second IGBT driving units 300 and 310 such that the first and the second heating coil units 500 and 510 operate at the same operation frequency according to the oscillation signal Ml output from the microprocessor 150.
[43] Such a structure of the IH controlling unit 200 includes an on-time controlling unit 210 outputting a switching on/off control signal for the first IGBT driving unit 300 to switch on the first heating coil unit 500, and outputting a switching on-off control signal for the second IGBT driving unit 310 to switch on the second heating coil unit 510 according to the oscillation signal Ml output from the microprocessor 150; an off- time controlling unit 230 controlling the on- time controlling unit 210 to output switching-off signals for the first heating coil unit 500 and the second heating coil unit 510; a feedback controlling unit 240 controlling operations of the off- time controlling unit 230 according to switching on/off control signals for the first heating coil unit 500 and the second heating coil unit 510, which are output from the on-time controlling unit 210; and a voltage follower circuit unit 250 providing the on-time controlling unit with a reference voltage, which determines an on-time duration of the on-time controlling unit 210, according to a compensation signal output from the output compensating unit 140.
[44] The on-time controlling unit 210 includes a comparator 211, in which signals input from the off-time controlling unit 230 and from the voltage follower circuit unit 250 are connected to a positive (+) input terminal thereof, a resistance Rl and a capacitor Cl determining a switching-on time of the on-time controlling unit 210, that is, a time to switch on the first heating coil unit 500 and the second heating coil unit 510, are connected to a negative (-) input terminal thereof, and switching on/off control signals for the first IGBT driving unit 300 and the second IGBT driving unit 310 are output at an output terminal thereof connected to the first IGBT driving unit 300 and the second IGBT driving unit 310, according to the signal input into the positive (+) input terminal thereof; and a diode D3, which is provided between the positive (+) input terminal and the negative (-) input terminal of the comparator 211, and maintains a voltage difference between the positive (+) input terminal and the negative (-) input terminal.
[45]
[46] *The off- time controlling unit 230 includes a comparator 231 , in which a resistance
R6 and a capacitor C2 determining switching-off times of the first heating coil unit 500 and the second heating coil unit 510 are connected in series, the resistance R6 and the capacitor C2 are connected to a positive (+) input terminal thereof, a reference voltage is connected to a negative (-) input terminal thereof, and an off signal of the on-time controlling unit 210 is output to the on-time controlling unit 210 through an output terminal thereof according to the time constants of the capacitor C2 and the resistance R6 connected to the positive (+) input terminal thereof; and a resistance R9, of which one side is connected to the feedback controlling unit 240, the other side is connected to the positive (+) input terminal of the comparator 231, which maintains that the voltage of the positive (+) input terminal of the comparator 231 is higher than the voltage of the negative (-) input terminal of the comparator 231 when a signal state of the feedback controlling unit 240 is converted from a high-level state into a low-level state.
[47] The feedback controlling unit 240 includes a transistor 241, of which a base stage is connected to the output terminal of the on-time controlling unit 210 through a resistance R5, and a collector stage is connected to the input terminal of the off-time controlling unit 230.
[48] In the feedback controlling unit 240, the transistor 241 is switched on/off according to a signal output from the output terminal of the on-time controlling unit 210, resulting in on/off of the off-time controlling unit 230.
[49] As described in FIG. 4, the feedback controlling unit 240 may be configured in such a manner as to have a diode D8 for discharging a current remaining in the base stage of the transistor 241 when the transistor 241 is switched off.
[50] As described in FIG. 5, alternatively to the structure using the transistor, the feedback controlling unit 240 may also be configured in such a manner as to have a comparator 242, in which the output of the on-time controlling unit 210 is connected and input to a negative (-) input terminal thereof, a reference voltage is connected to a positive (+) input terminal thereof, and an output terminal thereof is connected to the input terminal of the off-time controlling unit 230, so as to switch on/off the off-time controlling unit 230 according to the output signal of the on-time controlling unit 210, input to the negative (-) input terminal of the comparator 242.
[51] The voltage follower circuit unit 250 receives at least one of the output compensation signal provided by the output compensating unit 140 and the oscillation signal Ml output from the microprocessor 150, and provides the received signal as a reference voltage for determining an on-time duration of the on-time controlling unit 210, so that a time during which the on-time controlling unit 210 maintains a switched- on state can vary according to voltage changes and output changes. The voltage follower circuit unit 250 uses the well-known structure using an OP AMP 251.
[52] The first IGBT driving unit 300 outputs a control signal for an IGBT element 400 in such a manner that the first heating coil unit 500 which heats a cooking vessel (not shown) with a certain output is switched on/off, according to a signal output from the on-time controlling unit 210.
[53] The second IGBT driving unit 310 is connected in parallel to the first IGBT driving unit 300 and outputs a control signal for the IGBT element 410 in such a manner that the second heating coil unit 510 which heats the cooking vessel with a certain output is switched on/off the second heating coil unit 510 which heats the cooking vessel with a certain output, according to a signal output from the on-time controlling unit 210.
[54] Meanwhile, since the first and the second IGBT driving units 300 and 310 are switched on or switched off according to the on-off control signals (S 1 and S2) output from the microprocessor 150, only when the first and the second IGBT driving units 300 and 310 are switched on, the on-off switching of the first and the second heating coil units 500 and 510 are controlled by the first and the second IGBT driving units 300 and 310, according to the switching on/off control signal output from the IH controlling unit 200.
[55] Accordingly, it is possible to control two independent heating coils such that to drive both of two independent heating coils at the same time or to operate only one selected heating coil by using one control circuit.
[56] Also, while two independent heating coils have been described as an embodiment in the present invention, more than two independent heating coils, for example, three independent heating coils can be configured in such a manner as to be controlled.
[57] That is, it is possible to control three independent heating coils by including three independent heating coils and three IGBT driving units and three IGBT elements for controlling each of the three heating coils mentioned above, by connecting the three IGBT driving units to the IH controlling unit 200 in parallel, and by using the on/off signal of the microprocessor 150, so that each of the three heating coils is switched on/ off by one switching on/off signal output from the IH controlling unit 200.
[58] Accordingly, it is possible to control two or more heating coils by using one IH control circuit.
[59] The present invention has advantages in that it can provide an induction heating apparatus having a high output by using a plurality of independent heating coils, reduce the manufacturing process and improve the production efficiency by simplifying a control circuit.
[60] In the foregoing, an exemplary embodiment of the present invention has been illustrated and described. While the present invention is not limited to the embodiment described above, it will be understood by those skilled in the art to which the present invention belongs that various changes in forms and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims

Claims
[1] An IH circuit control apparatus comprising: a first IGBT driving unit outputting a control signal for switching on/off a first heating coil unit which heats a cooking vessel with a certain output according to a switching signal; a second IGBT driving unit outputting a control signal for switching on/off a second heating coil unit which heats the cooking vessel; a microprocessor outputting control signals for switching on/off the first IGBT driving unit and the second IGBT driving unit, and outputting an oscillation signal for switching control of the first IGBT driving unit and the second IGBT driving unit; an IH controlling unit simultaneously outputting switching on/off signals for the first IGBT driving unit and the second IGBT driving unit according to the oscillation signal output from the microprocessor; and an output compensating unit outputting a compensating signal to the IH controlling unit according to a change value detected from at least one of a voltage change value and an output change value of an utility power supply so as to vary switching-on times of the first and the second heating coil units.
[2] The IH circuit control apparatus of claim 1 , wherein switching-off times of the first heating coil unit and the second heating coil unit are constant.
[3] The IH circuit control apparatus of claim 1, wherein the IH controlling unit comprises: an on-time controlling unit outputting swithing-on signals for the first IGBT driving unit and the second IGBT driving unit so as to switch on the first heating coil unit and the second heating coil unit according to the oscillation signal output from the microprocessor; an off-time controlling unit outputting switching-off signals to the on-time controlling unit in such a manner that the on-time cntrolling unit switches off the first heating coil unit and the second heating coil unit; a feedback controlling unit controlling operations of the off-time controlling unit according to the switching on/off signals output from the on-time controlling unit; and a voltage follower circuit unit providing the on-time controlling unit with a reference voltage for determining an on-time duration of the on-time controlling unit, according to a compensation signal output from the output compensating unit.
[4] The IH circuit control apparatus of claim 3, wherein the on-time controlling unit comprises: a resistance and a capacitor determining switching-on times of the first heating coil unit and the second heating coil unit; a comparator, in which signals input from the off-time controlling unit and from the voltage follower circuit unit are connected to a positive (+) input terminal thereof, the resistance and the capacitor are connected to a negative (-) input terminal thereof, and switching on/off operation control signals for the first
IGBT driving unit and the second IGBT driving unit are output at an output terminal thereof, according to the signal input into the positive (+) input terminal thereof and the negative (-) input terminal thereof; and a diode maintaining a voltage difference between the positive (+) input terminal and the negative (-) input terminal of the comparator.
[5] The IH circuit control apparatus of claim 3, wherein the feedback controlling unit comprises: a transistor, of which a base stage is connected to the output terminal of the on- time controlling unit through a resistance, and a collector stage is connected to the off-time controlling unit, and wherein the transistor is switched on/off according to a signal output from the on-time controlling unit, resulting in on/off of the off-time controlling unit.
[6] The IH circuit control apparatus of claim 5, wherein the base stage of the transistor further comprises a diode for discharging a current remaining in the base stage of the transistor when the transistor is switched off.
[7] The IH circuit control apparatus of claim 3, wherein the feedback controlling unit comprises a comparator, where the output of the on-time controlling unit is connected to a negative (-) input terminal thereof, a reference voltage is connected to a positive (+) input terminal thereof, and an output terminal thereof is connected to the off-time controlling unit, and wherein the comparator switches on/off the off-time controlling unit according to the output signal of the on-time controlling unit, input to the negative (-) input terminal thereof.
[8] The IH circuit control apparatus of claim 3, wherein the off-time controlling unit comprises: a resistance and a capacitor determining switching-off times of the first heating coil unit and the second heating coil unit; a comparator, in which the resistance and the capacitor are connected to a positive (+) input terminal thereof, a reference voltage is connected to a negative (-) input terminal thereof, and an off signal of the on-time controlling unit is output to the on-time controlling unit through an output terminal thereof, according to the time constants of the capacitor and the resistance of the positive (+) input terminal thereof; and a resistance, of which one side is connected to the feedback controlling unit, the other side is connected to the positive (+) input terminal of the comparator, which maintains that the voltage of the positive (+) input terminal of the comparator is higher than the voltage of the negative (-) input terminal of the comparator when a signal state of the feedback controlling unit is converted from a high-level state into a low-level state.
PCT/KR2007/003425 2006-12-27 2007-07-13 Apparatus for controlling induction heating circuit WO2008078868A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR1020060134821A KR100784313B1 (en) 2006-12-27 2006-12-27 Apparatus for controlling induction heating circuit
KR10-2006-0134821 2006-12-27

Publications (1)

Publication Number Publication Date
WO2008078868A1 true WO2008078868A1 (en) 2008-07-03

Family

ID=39140524

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/KR2007/003425 WO2008078868A1 (en) 2006-12-27 2007-07-13 Apparatus for controlling induction heating circuit

Country Status (2)

Country Link
KR (1) KR100784313B1 (en)
WO (1) WO2008078868A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105992417A (en) * 2015-02-04 2016-10-05 佛山市顺德区美的电热电器制造有限公司 Heating control circuit for electric cooking device, and electric cooking device
JP2018521488A (en) * 2016-02-02 2018-08-02 佛山市▲順▼▲徳▼区美的▲電▼▲熱▼▲電▼器制造有限公司Ｆｏｓｈａｎ Ｓｈｕｎｄｅ Ｍｉｄｅａ Ｅｌｅｃｔｒｉｃａｌ Ｈｅａｔｉｎｇ Ａｐｐｌｉａｎｃｅｓ Ｍａｎｕｆａｃｔｕｒｉｎｇ Ｃｏ．，Ｌｉｍｉｔｅｄ Electromagnetic heating device, heating control circuit thereof, and low power heating control method

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111692616B (en) * 2019-03-12 2022-05-27 泰科电子(上海)有限公司 Multi-cooking-range electromagnetic oven

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10270161A (en) * 1997-03-24 1998-10-09 Matsushita Electric Ind Co Ltd Induction heating apparatus
JP2001196156A (en) * 2000-01-12 2001-07-19 Hitachi Hometec Ltd Induction cooker
JP2001267052A (en) * 2000-03-21 2001-09-28 Hitachi Hometec Ltd Induction heating cooker
JP2003264056A (en) * 2002-03-07 2003-09-19 Fuji Electric Co Ltd Controlling method of induction heating apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10270161A (en) * 1997-03-24 1998-10-09 Matsushita Electric Ind Co Ltd Induction heating apparatus
JP2001196156A (en) * 2000-01-12 2001-07-19 Hitachi Hometec Ltd Induction cooker
JP2001267052A (en) * 2000-03-21 2001-09-28 Hitachi Hometec Ltd Induction heating cooker
JP2003264056A (en) * 2002-03-07 2003-09-19 Fuji Electric Co Ltd Controlling method of induction heating apparatus

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105992417A (en) * 2015-02-04 2016-10-05 佛山市顺德区美的电热电器制造有限公司 Heating control circuit for electric cooking device, and electric cooking device
CN105992417B (en) * 2015-02-04 2024-04-16 佛山市顺德区美的电热电器制造有限公司 Heating control circuit of electric cooker and electric cooker
JP2018521488A (en) * 2016-02-02 2018-08-02 佛山市▲順▼▲徳▼区美的▲電▼▲熱▼▲電▼器制造有限公司Ｆｏｓｈａｎ Ｓｈｕｎｄｅ Ｍｉｄｅａ Ｅｌｅｃｔｒｉｃａｌ Ｈｅａｔｉｎｇ Ａｐｐｌｉａｎｃｅｓ Ｍａｎｕｆａｃｔｕｒｉｎｇ Ｃｏ．，Ｌｉｍｉｔｅｄ Electromagnetic heating device, heating control circuit thereof, and low power heating control method

Also Published As

Publication number Publication date
KR100784313B1 (en) 2007-12-13

Similar Documents

Publication Publication Date Title
US8415594B2 (en) Method for operating an induction heating device
TW200621094A (en) Induction-heating cooking heater
JP5677203B2 (en) Induction heating cooker
KR102326999B1 (en) Induction heat cooking apparatus and method for driving the same
CN101242144B (en) Method for controlling DC-DC converter
WO2008078868A1 (en) Apparatus for controlling induction heating circuit
WO2008078869A1 (en) Apparatus for controlling igbt selection of synchronous induction heating circuit
KR100351140B1 (en) Power factor correction apparatus of inverter
KR100726440B1 (en) Apparatus for controlling dual induction heating circuit
US10477625B2 (en) Cooking appliance
US20230049426A1 (en) Induction cooking device
JPH10270161A (en) Induction heating apparatus
CN101728965B (en) Resonance oscillation converter for improving synchronous rectification control
CN114553040A (en) Full-bridge inverse soft switching circuit and control method
JP3446507B2 (en) Induction heating cooker
CN210725393U (en) Heating control circuit and electromagnetic heating device
EP3937593B1 (en) Heating device and control method thereof
KR100513903B1 (en) Air conditioner
JP3257017B2 (en) Induction heating cooker
JP3024357B2 (en) Induction heating cooker
CN213152409U (en) Heating module and heating equipment
JP3780894B2 (en) Microwave generator
JP3334274B2 (en) Inverter device
KR101757976B1 (en) Induction heat cooking apparatus and method for driving the same
JP2512531B2 (en) Induction heating cooker

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 07768754

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 07768754

Country of ref document: EP

Kind code of ref document: A1