EP2914059A1 - Induktionsheizvorrichtung - Google Patents

Induktionsheizvorrichtung Download PDF

Info

Publication number: EP2914059A1
Authority: EP; European Patent Office
Prior art keywords: heating; heating coil; semiconductor switch; elements; load
Prior art date: 2012-10-24
Legal status (The legal status 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 status listed.): Granted

Application number

EP13848712.9A

Other languages

English (en)

French (fr)

Other versions

EP2914059B1 (de

EP2914059A4 (de

Inventor

Takeshi Kitaizumi

Yoichi Kurose

Tomoya Fujinami

Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)

Panasonic Intellectual Property Management Co Ltd

Original Assignee

Panasonic Intellectual Property Management 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.)

2012-10-24

Filing date

2013-10-23

Publication date

2015-09-02

2013-10-23 Application filed by Panasonic Intellectual Property Management Co Ltd filed Critical Panasonic Intellectual Property Management Co Ltd

2015-09-02 Publication of EP2914059A1 publication Critical patent/EP2914059A1/de

2015-11-04 Publication of EP2914059A4 publication Critical patent/EP2914059A4/de

2017-12-06 Application granted granted Critical

2017-12-06 Publication of EP2914059B1 publication Critical patent/EP2914059B1/de

Status Active legal-status Critical Current

2033-10-23 Anticipated expiration legal-status Critical

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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
- H05B2213/00—Aspects relating both to resistive heating and to induction heating, covered by H05B3/00 and H05B6/00
- H05B2213/03—Heating plates made out of a matrix of heating elements that can define heating areas adapted to cookware randomly placed on the heating plate
- 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
- H05B2213/00—Aspects relating both to resistive heating and to induction heating, covered by H05B3/00 and H05B6/00
- H05B2213/05—Heating plates with pan detection means

Definitions

This disclosure relates to induction heating devices including, for example, induction heating cooking devices heating an object to be heated by using induction heating with a high-frequency magnetic field.
FIG. 38 is a diagram showing a circuit configuration of a conventional induction heating device.
the conventional induction heating device is made up of an AC power source 101 that is a commercial power source, a rectification circuit 102 rectifying the commercial power source, a smoothing circuit 130 made up of a choke coil 104 and a smoothing capacitor 105 smoothing a rectified voltage from the rectification circuit 102, a first inverter 114 converting the output of the smoothing capacitor 105 into a high-frequency power to supply the high-frequency power to a first heating coil 106, a second inverter 115 converting the output of the smoothing capacitor 105 into a high-frequency power to supply the high-frequency power to a second heating coil 107, an input current detecting part 103 detecting an input current from the AC power source 101, and a control part 113.
the control part 113 is made up of a microcomputer etc., and controls an operation state of semiconductor switches in the first invert
the conventional induction heating device configured as described above has the rectification circuit 102, the choke coil 104, and the smoothing capacitor 105 shared by the two inverters 114 and 115, a circuit can be miniaturized.
the control part 113 controls a conduction time of the semiconductor switches in the first inverter 114 and the second inverter 115 such that an input current value of an input current from the AC power source 101 detected by the input current detecting part 103 made up of a current transformer etc. becomes equal to a preset current value.
a necessary high-frequency current is supplied to the first heating coil 106 and the second heating coil 107 connected to the first inverter 114 and the second inverter 115.
the high-frequency current supplied to the first heating coil 106 and the second heating coil 107 causes the first heating coil 106 and the second heating coil 107 to generate a high-frequency magnetic field, and the high-frequency magnetic field is applied to a load such as a pot magnetically coupled to the heating coils 106, 107.
the high-frequency magnetic field applied to the load such as a pot as described above generates an eddy current in the load, and the pot itself generates heat due to the eddy current and a skin resistance of the pot itself.
the control part 113 changes an input current to the first inverter 114 and the second inverter 115 to control the operation frequency and the conduction ratio of the semiconductor switches of the first inverter 114 and the second inverter 115 such that the detection value of the input current detecting part 103 attains a target value (see, e.g., Patent Literatures 1, 2).
a configuration using a plurality of heating coils is proposed so as to efficiently heat loads of various shapes when a load such as a pot or a pan is placed and heated on an upper surface made of crystallized glass etc.
Proposed shapes of heating coils include a configuration with a plurality of heating coils concentrically arranged, a configuration with a plurality of auxiliary coils having a different center position arranged around a heating coil, or a configuration with a plurality of small-shaped heating coils arranged in a matrix shape.
a configuration with an inverter provided for each of the heating coils increases a mounting area of the inverters, resulting in a problem that a device shape becomes larger.
a configuration using a plurality of heating coils generates an interference sound due to an operation frequency difference because a plurality of inverters operates at different operation frequencies.
a conventional induction heating device needs a semiconductor switch in an inverter driving each of a first heating coil and a second heating coil. Therefore, the conventional induction heating device needs a semiconductor switch and a driving circuit thereof for each inverter and needs a mounting area corresponding to the driving circuits, having a problem that it is difficult to further miniaturize the device.
a method of driving the respective heating coils at the same frequency or with a frequency difference equal to or greater than an audible range is proposed so as to suppress occurrence of an interference sound due to a difference in operation frequencies.
the operation frequency may not be the same depending on a type of a load and the interference sound may occur.
the method as described above also has a problem of complicated control of semiconductor switches making a circuit design difficult.
inductance and impedance such as a resistance value of a heating coil coupled to the load vary due to a difference in electric characteristics of the load even in such a conventional induction heating device and, therefore, a resonance characteristic varies that is determined by a value of a resonance capacitor connected to the heating coil.
some conventional induction heating devices utilize a method of adjusting a supply power to a load by changing an operation frequency depending on a resonance characteristic.
the control method of two heating coils alternately heating in a time division manner only for a constant time as described in JP H09-251888A has problems that a feeling of boiling is periodically lost in a resting period at the time of switchover and that a cooked object easily burns and sticks because one of the heating coils is supplied with a large electric power in a heating operation period in a method of alternately switching at constant time intervals.
a conventional induction heating device with a plurality of small-shaped heating coils arranged in a matrix shape, a plurality of small heating coils is driven in accordance with a shape of a load to be heated and, therefore, the impedance of the heating coils significantly varies depending on the number of the driven heating coils. As a result, it is very difficult to adjust the supply power to the load at the same operation frequency. If a load is heated by adjacent heating coils at the same time, different operation frequencies generate an interference sound due to a difference in the operation frequencies, resulting in a problem such as that a noise becomes louder.
the present disclosure solves various conventional problems and it is an object of this disclosure to provide an induction heating device generating no interference sound even when a high-frequency power is supplied to a plurality of heating coils, having an excellent cooking performance corresponding to a state of a load, and having the reduced number of components, a small circuit mounting area, and a low production cost.
An induction heating device of a first aspect according to the present disclosure comprises:
the induction heating device of the present disclosure can provide an induction heating device generating no interference sound even when a high-frequency power is supplied to a plurality of heating coils, having an excellent cooking performance corresponding to a state of a load, and having the reduced number of components, a small circuit mounting area, and a low production cost.
a specific configuration example of an induction heating device according to this disclosure will be described in detail in first to eighth embodiments described later, and the induction heating device according to this disclosure has a configuration having the following aspects.
An induction heating device of a first aspect according to the present disclosure comprises:
the induction heating device of the first aspect configured as described above can supply the high-frequency power to a plurality of the heating coils at the same time, generates no interference sound even when the high-frequency power is supplied to a plurality of the heating coils, has an excellent cooking performance as well as the reduced number of components, and therefore can provide an inexpensive induction heating device with a small circuit mounting area.
An induction heating device of a second aspect is configured that in the first aspect, a resonance frequency generated by a first resonance circuit made up of the first heating coil and the first resonance capacitor becomes the same as a resonance frequency generated by a second resonance circuit made up of the second heating coil and the second resonance capacitor.
the induction heating device of the second aspect configured as described above can substantially uniformly supply the high-frequency power from the heating coils to the load when the same load is heated by a plurality of the heating coils. Therefore, the induction heating device of the second aspect can uniformly finish an object to be heated such as a cooked object and acts as an induction heating device with improved usability.
An induction heating device of a third aspect is configured that in the first aspect or the second aspect, when the high-frequency power is supplied to both the first heating coil and the second heating coil, the control part controls the first semiconductor switch, the second semiconductor switch, and the third semiconductor switch such that an average power supplied to both the first heating coil and the second heating coil attains a target value by changing a ratio between a period in the simultaneous heating mode and a period in the first single heating mode or the second single heating mode.
the induction heating device of the third aspect configured as described above can supply different high-frequency powers to the load on the heating coils to enable fine power adjustment, and can achieve an induction heating device with improved usability.
An induction heating device of a fourth aspect according to the present disclosure is configured that in the first aspect, when the high-frequency power is supplied to both the first heating coil and the second heating coil, the control part performs an alternate heating mode in which each of the first single heating mode and the second single heating mode is repeated in a short period within one second, so as to supply the high-frequency power uniformly to both the first heating coil and the second heating coil.
the induction heating device of the fourth aspect configured as described above generates no interference sound even when the high-frequency power is supplied to a plurality of the heating coils, has an excellent cooking performance as well as the reduced number of components, and therefore can achieve an inexpensive induction heating device with a small circuit mounting area.
An induction heating device of a fifth aspect according to the present disclosure is configured that in the fourth aspect, a state transition between the first single heating mode and the second single heating mode is performed in the alternate heating mode when the second semiconductor switch is in a non-conductive state.
the induction heating device of the fifth aspect configured as described above does not particularly require a resting period provided at the time of switchover between the first single heating mode and the second single heating mode and can switch the heating coil supplying the high-frequency power at high speed.
a device user can feel a cooking status equivalent to when each of multiple loads is continuously heated and the induction heating device of this disclosure can achieve a cooking performance with improved usability.
An induction heating device of a sixth aspect according to the present disclosure is configured that in the fourth aspect or the fifth aspect, when the high-frequency power is supplied to both the first heating coil and the second heating coil, the control part controls a continuous operation time of the first single heating mode and a continuous operation time of the second single heating mode in the alternate heating mode to be the same ratio and changes operation frequencies or conduction times of two semiconductor switches out of the first semiconductor switch, the second semiconductor switch, and the third semiconductor switch supplying the high-frequency power to the first heating coil and the second heating coil in the first single heating mode and the second single heating mode, so as to control an input power.
the induction heating device of the sixth aspect configured as described above can finely perform the power adjustment and therefore can achieve an induction heating device with improved usability.
An induction heating device of a seventh aspect is configured that in the fourth aspect or the fifth aspect, when the high-frequency power is supplied to both the first heating coil and the second heating coil, the control part sets operation frequencies or conduction times of two semiconductor switches constant out of the first semiconductor switch, the second semiconductor switch, and the third semiconductor switch supplying the high-frequency power to the first heating coil and the second heating coil in the first single heating mode and the second single heating mode in the alternate heating mode and changes a ratio of a continuous operation time of the first single heating mode and a continuous operation time of the second single heating mode, so as to control an input power.
the induction heating device of the seventh aspect configured as described above can perform the power adjustment in a larger range and therefore can achieve an induction heating device with improved usability.
An induction heating device of an eighth aspect according to the present disclosure is configured that in the first aspect, the first heating coil is made up of a plurality of first heating coil elements while the first resonance capacitor is made up of a plurality of first resonance capacitor elements such that the plurality of the first heating coil elements is respectively connected to the plurality of the first resonance capacitor elements to form a plurality of series connection bodies connected in parallel to the first semiconductor switch, wherein the second heating coil is made up of a plurality of second heating coil elements while the second resonance capacitor is made up of a plurality of second resonance capacitor elements such that the plurality of the second heating coil elements is respectively connected to the plurality of the second resonance capacitor elements to form a plurality of series connection bodies connected in parallel to the third semiconductor switch, and wherein the control part controls the first semiconductor switch, the second semiconductor switch, and the third semiconductor switch so as to switch between an alternate heating mode in which the first single heating mode and the second signal heating mode are alternately repeated and the simultaneous heating mode depending on a material of a load.
the induction heating device of the eighth aspect configured as described above can operate the first to third semiconductor switches in the simultaneous heating mode in the case of a material making the impedance of the load coupled to the heating coils lager and can operate the first to third semiconductor switches in the alternate heating mode in the case of a material making the impedance of the load coupled to the heating coils smaller, thereby bringing the impedances close to each other even when the materials are different. Therefore, the induction heating device of this disclosure can achieve an induction heating device that can apply necessary input power to a load at a constant frequency even if the material of the load is changed, that generates no interference sound, and that is excellent in controllability.
An induction heating device of a ninth aspect according to the present disclosure is configured that in the eighth aspect, the control part has a step-down simultaneous heating mode in which the first semiconductor switch and the third semiconductor switch are caused to perform the same on/off operation while the on/off operation of the first semiconductor switch and the third semiconductor switch are performed alternately with an on/off operation of the second semiconductor switch so as to supply the high-frequency power to the first heating coil and the second heating coil at the same time, and wherein the control unit can selectively switch the simultaneous heating mode, the alternate heating mode, and the step-down simultaneous heating mode depending on a material of a load.
the induction heating device of the ninth aspect configured as described above can operate the first to third semiconductor switches in the simultaneous heating mode in the case of a material making the impedance of the load coupled to the heating coils lager and can operate the first to third semiconductor switches in the step-down simultaneous heating mode in the case of a material making the impedance of the load coupled to the heating coils smaller, thereby bringing the impedances close to each other even when the materials are different. Therefore, the induction heating device of this disclosure can achieve an induction heating device that can supply necessary input power at a constant frequency to a load even if the material of the load is changed, that generates no interference sound, and that is excellent in controllability.
an induction heating device of a tenth aspect is configured that in the eighth aspect or the ninth aspect, the induction heating device further comprises a load detecting part detecting the presence of a heatable load in the vicinity of each of the first heating coli elements and the second heating coil elements, a plurality of first opening/closing part elements detaching the respective series connection bodies of the first heating coil elements and the first resonance capacitor elements from an energizing path for parallel connection to the first semiconductor switch, and a plurality of second opening/closing part elements detaching the respective series connection bodies of the second heating coil elements and the second resonance capacitor elements from an energizing path for parallel connection to the third semiconductor switch, wherein the control part puts into a connected state the first opening/closing part elements and/or the second opening/closing part elements corresponding to the first heating coil elements and/or the second heating coil elements having a load detected in the vicinity thereof by the load detecting part.
the induction heating device of the tenth aspect configured as described above can supply a desired high-frequency power to the load from the appropriate heating coils in accordance with the shape of the load.
the induction heating device of this disclosure can achieve a heating device heating the load with uniform heating distribution and having a high heating efficiency.
an induction heating device of an eleventh aspect is configured that in the eighth aspect or the ninth aspect, the induction heating device further comprises a load detecting part detecting the presence of a heatable load in the vicinity of each of the first heating coli elements and the second heating coil elements, a plurality of first opening/closing part elements detaching the respective series connection bodies of the first heating coil elements and the first resonance capacitor elements from an energizing path for parallel connection to the first semiconductor switch, and a plurality of second opening/closing part elements detaching the respective series connection bodies of the second heating coil elements and the second resonance capacitor elements from an energizing path for parallel connection to the third semiconductor switch, wherein the control part controls into a connected state the first opening/closing part elements and/or the second opening/closing part elements corresponding to the first heating coil elements and/or the second heating coil elements having a load detected in the vicinity thereof by the load detecting part and selectively switches the simultaneous heating mode, the alternate heating mode, and the step-down simultaneous heating mode
the induction heating device of the eleventh aspect configured as described above can achieve an induction heating device that can supply a predetermined input power at a constant frequency to the load even when the number of the heating coils is changed, that generates no interference sound, and that is excellent in controllability.
the induction heating device of the eleventh aspect can change impedance and applied voltage of a heating coil group depending on the number of the heating coil elements making up the first heating coil and the second heating coil and therefore can perform the power adjustment with the operation frequency kept constant.
the induction heating device of the eleventh aspect can perform the simultaneous heating mode if the number of the heating coil elements is small and the impedance is made larger, and can perform the alternate heating mode if the number of the heating coil elements is large and the impedance is made smaller, so as to supply a predetermined input power at a constant frequency to the load even when the number of the connected heating coil elements is changed, and can achieve an induction heating device that generates no interference sound and that is excellent in controllability.
An induction heating device of a twelfth aspect according to the present disclosure is configured that in the eighth aspect or the ninth aspect, the first heating coil elements making up the first heating coil and the second heating coil elements making up the second heating coil are arranged in a staggered manner in a planar heating region.
the induction heating device of the twelfth aspect configured as described above can uniformly supply the high-frequency power from the element heating coils to the load and therefore can achieve an induction heating device that forms favorable heating distribution for the load.
induction heating cooker will hereinafter be described as embodiments according to the induction heating device of this disclosure with reference to the accompanying drawings.
the induction heating device of the present disclosure is not limited to the configuration of the induction heating cooker described in the following embodiments and include a device configured based on technical ideas equivalent to technical ideas described in the following embodiments.
Fig. 1 is a diagram of a circuit configuration of the induction heating device of the first embodiment.
the induction heating device of the first embodiment is made up of an AC power source 1; a rectification circuit 2 rectifying the AC power source 1; a smoothing circuit 30 having a choke coil 4 and a smoothing capacitor 5 smoothing the current/voltage of the rectification circuit 2; a series connection body of a first semiconductor switch 10, a second semiconductor switch 11, and a third semiconductor switch 12 connected in parallel to the smoothing capacitor 5 operating as a DC power source; a series connection body of a first heating coil 6 and a first resonance capacitor 8 connected in parallel to the first semiconductor switch 10; a series connection body of a second heating coil 7 and a second resonance capacitor 9 connected in parallel to the third semiconductor switch 12; an input current detecting part 3 detecting a current flowing from the AC power source 1 to the rectification circuit 2 with a current transformer etc.; and a control part 13 controlling the first to third semiconductor switches 10, 11, and 12 such
a target value of the control part 13 in the induction heating device of this disclosure can be implemented by using the currents and/or voltages of the heating coils 6 and 7 besides the input current and is not particularly limited in this disclosure.
the semiconductor switches in the induction heating device of this disclosure are often made up of power semiconductors (semiconductor switch elements), such as IGBTs or MOSFETs, and diodes connected in parallel to the respective power semiconductors in the opposite direction, and each of the first to third semiconductor switches 10, 11, and 12 of the first embodiment is made up of a power semiconductor of IGBT and a diode connected in parallel to the power semiconductor in the opposite direction.
power semiconductors semiconductor switch elements
IGBTs or MOSFETs MOSFETs
a snubber capacitor suppressing a rapid voltage rise at the time of shift from the on-state to the off-state is often connected in parallel between a collector and an emitter of the first to third semiconductor switches 10, 11, and 12, and the configuration of the first embodiment is described as an example of connecting a snubber capacitor in parallel to the first semiconductor switch 10 and the third semiconductor switch 10, 12.
Figs. 2A and 2B are waveform diagrams of an operation (an alternate heating mode) in the induction heating device of the first embodiment according to this disclosure.
the alternate heating mode is a heating mode alternately repeating a first single heating mode and a second single heating mode described later in a short cycle.
Fig. 2A is a waveform diagram of the first single heating mode in which a high-frequency power is supplied to the second heating coil 7, and depicts gate voltage waveforms (a) to (c) of the first to third semiconductor switches 10, 11, 12 and a current waveform (d) of the second heating coil 7.
Fig. 1 is a waveform diagram of the first single heating mode in which a high-frequency power is supplied to the second heating coil 7, and depicts gate voltage waveforms (a) to (c) of the first to third semiconductor switches 10, 11, 12 and a current waveform (d) of the second heating coil 7.
2B is a waveform diagram of the second single heating mode in which a high-frequency power is supplied to the first heating coil 6, and depicts gate voltage waveforms (a) to (c) of the first to third semiconductor switches 10, 11, 12 and a current waveform (d) of the first heating coil 6.
the first single heating mode of supplying a high-frequency power to the second heating coil 7 depicted in Fig. 2A will first be described.
the control part 13 puts the first semiconductor switch (Q1a) 10 into a constantly conductive state and controls a conductive state/non-conductive state (on-state/off-state) of the second semiconductor switch (Q1b) 11 and the third semiconductor switch (Q1c) 12.
the control part 13 puts the second semiconductor switch (Q1b) 11 into the conductive state (on-state) and the third semiconductor switch (Q1c) 12 into the non-conductive state (off-state).
the control part 13 puts only the second semiconductor switch (Q1b) 11 into the non-conductive state at the conduction time when the current value detected by the input current detecting part 3 indicates a predetermined current value (termination of the section A).
the control part 13 puts the third semiconductor switch (Q1c) 12 into the conductive state.
a path is formed from the second resonance capacitor 9 ⁇ the second heating coil 7 ⁇ the third semiconductor switch (Q1c) 12, and the power is supplied to the second heating coil 7.
the control part 13 puts the third semiconductor switch (Q1c) 12 into the non-conductive state at the conduction time (section B) when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section B).
control part 13 After a predetermined transition time (section Y) has elapsed, the control part 13 puts the second semiconductor switch (Q1b) 11 into the conductive state (section A). As described above, the control part 13 allows the operations of the section A and the section B to continue via the transmission time (X or Y) as depicted in Fig. 2A .
the control part 13 can put the second semiconductor switch (Q1b) 11 and the third semiconductor switch (Q1c) 12 alternately into the conductive state while keeping the first semiconductor switch (Q1a) 10 in the conductive state, thereby supplying a high-frequency current of about 20 kHz to 60 kHz to the second heating coil 7.
the high-frequency current supplied in this way causes the second heating coil 7 to generate a high-frequency magnetic field and the high-frequency magnetic field is supplied to a load such as a pot that is an object to be heated.
the high-frequency magnetic field supplied to the load such as a pot in this way generates an eddy current on a surface of the pot etc., and the load such as the pot is inductively heated due to the eddy current and a high-frequency resistance of the load such as a pot itself, which leads to heat generation.
the second single heating mode of supplying a high-frequency power to the first heating coil 6 will be described with reference to Fig. 2B .
the control part 13 puts the third semiconductor switch (Q1c) 12 into the constantly conductive state and controls the conductive state/non-conductive state (on-state/off-state) of the first semiconductor switch (Q1a) 10 and the second semiconductor switch (Q1b) 11.
the control part 13 puts the second semiconductor switch (Q1b) 11 into the conductive state in the section A depicted in Fig. 2B , a path is formed from the smoothing capacitor 5 ⁇ the first resonance capacitor 8 ⁇ the first heating coil 6 ⁇ the second semiconductor switch (Q1b) 11 ⁇ the third semiconductor switch (Q1c) 12, and the power is supplied to the first heating coil 6.
the control part 13 puts only the second semiconductor switch (Q1b) 11 into the non-conductive state at the conduction time when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section A).
the control part 13 puts the first semiconductor switch (Q1a) 10 into the conductive state.
the power is supplied to the first heating coil 6 through a path from the first resonance capacitor 8 ⁇ the first semiconductor switch (Q1a) 10 ⁇ the first heating coil 6 (section B).
the control part 13 puts the first semiconductor switch (Q1a) 10 into the non-conductive state at the conduction time when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section B).
the control part 13 puts the second semiconductor switch (Q1b) 11 into the conductive state (section A). As described above, the control part 13 allows the operations of the section A and the section B to continue via the transmission time (X or Y) as depicted in Fig. 2B .
the control part 13 can put the first semiconductor switch (Q1a) 10 and the second semiconductor switch (Q1b) 11 alternately into the conductive state while keeping the third semiconductor switch (Q1c) 12 in the conductive state, thereby supplying a high-frequency current of about 20 kHz to 60 kHz to the first heating coil 6.
the high-frequency current supplied in this way causes the first heating coil 6 to generate a high-frequency magnetic field and the high-frequency magnetic field is supplied to a load such as a pot that is an object to be heated. Because of the high-frequency magnetic field supplied to the load such as a pot in this way, the load such as the pot is inductively heated, which leads to heat generation.
Fig. 3 is a waveform diagram of an operation of the simultaneous heating mode in the induction heating device of the first embodiment of this disclosure.
Fig. 3 includes (a) to (c) as gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, (d) as a current waveform of the first heating coil 6, and (e) as a current waveform of the second heating coil 7.
the control part 13 puts the second semiconductor switch (Q1b) 11 into the constantly conductive state and controls the conductive state/non-conductive state (on-state/off-state) of the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12.
the control of putting the first semiconductor switch (Q1a) 10 into the conductive state (on-state) and putting the third semiconductor switch (Q1c) 12 into the non-conductive state (off-state) simultaneously generates the mode of supplying a power to the second heating coil 7 through the path from the smoothing capacitor 5 ⁇ the first semiconductor switch (Q1a) 10 ⁇ the second semiconductor switch (Q1b) 11 ⁇ the second heating coil 7 ⁇ the second resonance capacitor 9, and the mode of supplying a power to the first heating coil 6 through the path from the first resonance capacitor 8 ⁇ the first semiconductor switch (Q1a) 10 ⁇ the first heating coil 6.
the control part 13 puts only the first semiconductor switch (Q1a) 10 into the non-conductive state at the conduction time when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section A of Fig. 3 ).
the control part 13 puts the third semiconductor switch (Q1c) 12 into the conductive state.
this simultaneously generates the operation of supplying a power to the first heating coil 6 through the path from the smoothing capacitor 5 ⁇ the first resonance capacitor 8 ⁇ the first heating coil 6 ⁇ the second semiconductor switch (Q1b) 11 ⁇ the third semiconductor switch (Q1c) 12, and the operation of supplying a power to the second heating coil 7 through the path from the second resonance capacitor 9 ⁇ the second heating coil 7 ⁇ the third semiconductor switch (Q1c) 12.
the control part 13 puts only the third semiconductor switch (Q1c) 12 into the non-conductive state at the conduction time (section B) when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section B of Fig. 3 ). Subsequently, after the predetermined transition time (section Y) has elapsed, the control part 13 puts the first semiconductor switch (Q1a) 10 into the conductive state again.
the control part 13 can put the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12 alternately into the conductive state while keeping the second semiconductor switch (Q1b) 11 in the conductive state, thereby supplying a high-frequency current of about 20 kHz to 60 kHz to both the first heating coil 6 and the second heating coil 7 at the same time.
the high-frequency magnetic field generated from the heating coils supplied with the high-frequency current is supplied to the load such as a pot.
the induction heating device of the first embodiment can supply the power independently to, or simultaneously without an interference sound to, the loads present respectively on the first heating coil 6 and the second heating coil 7.
advantages can be acquired, including that a load can uniformly be heated when the same load is heated by the two heating coils 6, 7 at the same time.
Fig. 4 is a waveform diagram of an operation using a plurality of heating modes in the induction heating device of the first embodiment according to this disclosure.
Fig. 4 depicts the operation when the high-frequency power is simultaneously supplied to the first heating coil 6 and the second heating coil 7 and different powers are supplied to the respective heating coils 6, 7.
the first heating coil 6 has a supply power set larger than the second heating coil 7.
control part 13 provides the control such that the device operates in the simultaneous heating mode (see Fig. 3 ) in which the power is supplied to the first heating coil 6 and the second heating coil 7 at a set value of the first heating coil 6 having a larger supply power between the first heating coil 6 and the second heating coil 7.
the control part 13 shifts the operation to the second signal heating mode (see Fig. 2B ) in which the power is supplied only to the first heating coil 6 without supplying a power to the second heating coil 7 having a smaller supply power. Subsequently, when a non-conduction time has elapsed that is determined by an average power supplied to the second heating coil 7, the control part 13 makes a shift from the second signal heating mode to the simultaneous heating mode again.
the loads present on the two heating coils 6, 7 can be heated at a desired power without generating an interference sound while a user is prevented from having a strong feeling of difference.
the supply power of the first heating coil 6 is larger than the supply power of the second heating coil 7 in the configuration described in the first embodiment, if the supply power of the second heating coil 7 is configured to be larger than the supply power of the first heating coil 6, the simultaneous heating mode and the first single heating mode can alternately be repeated to properly supply the desired power to the first heating coil 6 and the second heating coil 7 so as to acquire the same effect as the configuration described above.
Fig. 5 is diagrams of an appearance configuration of the induction heating device of the first embodiment according to this disclosure and (a) on the upper side is a plane view while (b) on the lower side is a vertical cross-sectional view taken in the substantially center portion of the first heating coil 6 disposed closer to a user.
the induction heating device of the first embodiment has the first heating coil 6 and the second heating coil 7 arranged under a top plate 18 made of crystallized glass etc.
Respective loads such as pots containing a cooked object are placed on the first heating coil 6 and the second heating coil 7, and the plurality of the heating modes (the first single heating mode, the second single heating mode, and the simultaneous heating mode) described above are appropriately used in accordance with an operation from an operation/display part 17 so as to properly supply necessary powers to the respective heating coils 6, 7.
the induction heating device of the first embodiment can operate in the plurality of the heating modes (the first single heating mode, the second single heating mode, and the simultaneous heating mode) described above so as to perform cooking with a power corresponding to each type of cooking.
Fig. 6 is diagrams of another configuration example of the induction heating device of the first embodiment according to this disclosure.
the induction heating device depicted in Fig. 6 has the first heating coil 6 and the second heating coil 7 in an oval shape arranged under one heating region H indicated on the top plate 18 made of crystallized glass etc., and is configured such that one load such as a pot can be heated by the two heating coils 6, 7 at the same time.
the oval heating coils 6, 7 are arranged in parallel such that the major axes are located on lines extending from the user side toward a back surface of the device.
Fig. 6 is diagrams of another configuration example of the induction heating device of the first embodiment according to this disclosure.
the induction heating device depicted in Fig. 6 has the first heating coil 6 and the second heating coil 7 in an oval shape arranged under one heating region H indicated on the top plate 18 made of crystallized glass etc., and is configured such that one load such as a pot can be heated by the two heating coils 6, 7 at the same
FIG. 6 (a) on the upper side is a plane view and (b) on the lower side is a vertical cross-sectional view taken in the substantially center portions of the first heating coil 6 and the second heating coil 7.
the induction heating device depicted in Fig. 6 can perform heating and cooking with uniform heating distribution without an interference sound when a plurality of the heating coils is used for heating a single load.
a plurality of resonance circuits made up of heating coils inductively heating a load and resonance capacitors are connected to three serially-connected semiconductor switches and, while one semiconductor switch of the three semiconductor switches is in the constantly conductive state (on-state) as a semiconductor switch determining a heating coil supplied with power, the operation in the single heating mode is used in which the remaining semiconductor switches are used as semiconductor switches controlled to the conductive state/non-conductive state (on/off-state) for supplying the high-frequency power to the heating coils, along with the simultaneous heating mode in which the second semiconductor switch is put into the constantly conductive state.
the induction heating device of the first embodiment can supply power to a plurality of the heating coils at the same time, generates no interference sound even when supplying the high-frequency power to a plurality of the heating coils, and has excellent cooking performance.
the configuration of the first embedment has the reduced number of components and therefore leads to an inexpensive induction heating device with a small circuit mounting area.
the induction heating device of the second embodiment is useful when two heating coils have different operation frequencies due to a difference in material etc. of a load such as a pot, or when impedance of a load is small.
the induction heating device of the second embodiment has a configuration preventing the interference sound in an alternate heating mode in which the first single heating mode and the second single heating mode described in the first embodiment are properly alternately switched in a short period of time.
elements having substantially the same functions and configurations as those of the first embodiment described above will be denoted by the same reference numerals and will not be described.
Fig. 7 is a diagram of a circuit configuration of the induction heating device of the second embodiment according to this disclosure.
the induction heating device of the second embodiment has the similar circuit configuration as the induction heating device of the first embodiment described above, and is made up of the AC power source 1; the rectification circuit 2; the smoothing circuit 30; the series connection body of the first to third semiconductor switches 10, 11, 12; a series connection body of the first heating coil 6 and the first resonance capacitor 8; a series connection body of the second heating coil 7 and the second resonance capacitor 9; the input current detecting part 3; and the control part 13.
the first to third semiconductor switches 10, 11, and 12 are made up of power semiconductors (semiconductor switch elements), such as IGBTs or MOSFETs, and diodes connected in parallel to the respective power semiconductors in the opposite direction.
a snubber capacitor suppressing a rapid voltage rise at the time of shift from the on-state to the off-state may be connected in parallel between a collector and an emitter of the first to third semiconductor switches 10, 11, and 12.
a snubber capacitor is connected in parallel between the collector and the emitter of the first semiconductor switch 10 and the third semiconductor switch 12.
Figs. 8A and 8B are waveform diagrams of an operation (the alternate heating mode) in the induction heating device of the second embodiment according to this disclosure.
Fig. 8A is a waveform diagram of the first single heating mode in which the high-frequency power is supplied to the second heating coil 7, and depicts gate voltage waveforms (a) to (c) of the first to third semiconductor switches 10, 11, 12 and a current waveform (d) of the second heating coil 7.
Fig. 8A is a waveform diagram of the first single heating mode in which the high-frequency power is supplied to the second heating coil 7, and depicts gate voltage waveforms (a) to (c) of the first to third semiconductor switches 10, 11, 12 and a current waveform (d) of the second heating coil 7.
Fig. 8A is a waveform diagram of the first single heating mode in which the high-frequency power is supplied to the second heating coil 7, and depicts gate voltage waveforms (a) to (c) of the first to third semiconductor switches 10, 11, 12 and a current waveform (d)
8B is a waveform diagram of the second single heating mode in which the high-frequency power is supplied to the first heating coil 6, and depicts gate voltage waveforms (a) to (c) of the first to third semiconductor switches 10, 11, 12 and a current waveform (d) of the first heating coil 6.
the control part 13 puts the first semiconductor switch (Q1a) 10 into the constantly conductive state and controls the conductive state/non-conductive state (on-state/off-state) of the second semiconductor switch (Q1b) 11 and the third semiconductor switch (Q1c) 12.
the control part 13 puts the first semiconductor switch (Q1a) 10 and the second semiconductor switch (Q1b) 11 into the conductive state (on-state) and the third semiconductor switch (Q1c) 12 into the non-conductive state (off-state).
the control part 13 puts only the second semiconductor switch (Q1b) 11 into the non-conductive state at the conduction time (Tb) when the current value detected by the input current detecting part 3 indicates the predetermined current value.
the control part 13 puts the third semiconductor switch (Q1c) 12 into the conductive state.
a path is formed from the second resonance capacitor 9 ⁇ the second heating coil 7 ⁇ the third semiconductor switch (Q1c) 12, and the power is supplied to the second heating coil 7.
the control part 13 puts the third semiconductor switch (Q1c) 12 into the non-conductive state at the conduction time (Tc) when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section B).
control part 13 puts the second semiconductor switch (Q1b) 11 into the conductive state (section A). As described above, the control part 13 allows the operations of the section A and the section B to continue alternately via the transmission time (X or Y).
control part 13 can put the second semiconductor switch (Q1b) 11 and the third semiconductor switch (Q1c) 12 alternately into the conductive state while keeping the first semiconductor switch (Q1a) 10 in the conductive state, thereby supplying a high-frequency current of about 20 kHz to 60 kHz to the second heating coil 7.
the high-frequency magnetic field generated from the second heating coil 7 due to the high-frequency current supplied in this way is supplied to the load such as a pot.
the high-frequency magnetic field supplied to the load such as a pot in this way generates an eddy current on a surface of the load such as a pot, and the load such as a pot is inductively heated due to the eddy current and a high-frequency resistance of the load such as a pot itself, which leads to heat generation.
the second single heating mode of supplying a high-frequency power to the first heating coil 6 will be described with reference to Fig. 8B .
the control part 13 puts the third semiconductor switch (Q1c) 12 into the constantly conductive state and controls the conductive state/non-conductive state (on-state/off-state) of the first semiconductor switch (Q1a) 10 and the second semiconductor switch (Q1b) 11.
the control part 13 puts the second semiconductor switch (Q1b) 11 into the conductive state in the section A depicted in Fig. 8B , a path is formed from the smoothing capacitor 5 ⁇ the first resonance capacitor 8 ⁇ the first heating coil 6 ⁇ the second semiconductor switch (Q1b) 11 ⁇ the third semiconductor switch (Q1c) 12, and the power is supplied to the first heating coil 6.
the control part 13 puts only the second semiconductor switch (Q1b) 11 into the non-conductive state at the conduction time (Tb) when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section A of Fig. 8B ). After the predetermined transition time (section X) has elapsed, the control part 13 puts the first semiconductor switch (Q1a) 10 into the conductive state.
the control part 13 puts the first semiconductor switch (Q1a) 10 into the non-conductive state at the conduction time (Ta) when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section B of Fig. 8B ).
the control part 13 puts the second semiconductor switch (Q1b) 11 into the conductive state (section A).
the control part 13 allows the operations of the section A and the section B to continue via the transmission time (X or Y).
the control part 13 can put the first semiconductor switch (Q1a) 10 and the second semiconductor switch (Q1b) 11 alternately into the conductive state while keeping the third semiconductor switch (Q1c) 12 in the conductive state, thereby supplying a high-frequency current of about 20 kHz to 60 kHz to the first heating coil 6.
the high-frequency magnetic field generated from the heating coil due to the high-frequency current supplied in this way is supplied to the load such as a pot.
Fig. 9 is a waveform diagram of an operation of the alternate heating mode in the induction heating device of the second embodiment.
the alternate heating mode is the operation when the first single heating mode and the second single heating mode described above are alternately used for heating a plurality of loads.
Fig. 9 includes (a) to (c) as gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, (d) as a current waveform of the second heating coil 7, and (e) as a current waveform of the first heating coil 6.
an operation time of the first single heating mode is T2 and an operation time of the second single heating mode is T1. Therefore, in the second embodiment, the operation time T1 and the operation time T2 are set to a very short cycle.
Each of the operation time T1 and the operation time T2 is set to, for example, one second or less, and one cycle (T1+T2) of the alternate heating mode is set to a very short cycle within two seconds.
the device in the alternate heating mode, can be operated in the first single heating mode and the second single heating mode alternately in a short cycle so as to perform the heating operation for a load placed on the second heating coil 7 and a load placed on the first heating coil substantially at the same time.
control part 13 can change the heating coil supplied with power simply by changing the operation states of the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c).
the switchover operation between the first single heating mode and the second single heating mode in the alternate heating mode can switch the heating modes within approximately one second to maintain a continuously boiling state when boiling water. Therefore, as compared to the case of simultaneous heating using a plurality of the heating coils, an equivalent performance can be acquired.
Fig. 10 is a waveform diagram at the time of the switchover operation between the first single heating mode and the second single heating mode in the alternate heating mode of the induction heating device of the second embodiment.
Fig. 10 depicts the operation state at the time of switching the heating coil supplied with power from the first single heating mode to the second single heating mode at a high speed.
the control part 13 puts the first semiconductor switch (Q1a) into the non-conductive state for switching to the second single heating mode.
the control part 13 puts the third semiconductor switch (Q1c) 12 into the non-conductive state for switching to the first single heating mode.
the heating coil to be supplied with power can smoothly be switched in a short time.
the alternate heating mode can eliminate the occurrence of interference sound due to a difference in operation frequencies.
Figs. 11A and 11B are diagrams for explaining the power characteristics in the induction heating device of the second embodiment and depict the characteristics when amounts of power supplied to the first heating coil 6 and the second heating coil 7 are changed.
Fig. 11A is a characteristic diagram showing characteristics of a conduction time [ ⁇ sec] and an input power [W] of a semiconductor switch (at a constant operation frequency).
Fig. 11B is a characteristic diagram of characteristics of an operation frequency [kHz] and an input power [W] of a semiconductor switch (at a constant on-time ratio).
a transition time between the heating modes must be made short so as to perform the heating in a continuous manner.
Fig. 12 is a diagram of electric characteristics of the alternate heating mode in the induction heating device of the second embodiment.
Fig. 12 depicts changes in amounts of power supplied to the first heating coil 6 and the second heating coil 7 when a conduction time ratio (T1/TL) of the second single heating mode in one cycle (TL) is changed in the alternate heating mode.
T1/TL conduction time ratio
the powers supplied to the first heating coil 6 and the second heating coil 7 are determined by a conduction time ratio during the power supply to the respecting heating coils 6, 7. Therefore, if the supply power to one of the heating coils is increased, the conduction time ratio for the power supply to the heating coils must be changed. In this case, to prevent a user from having a feeling of difference from actual simultaneous heating in the alternate heating mode, it is desirable to change only the conduction time ratio with a cycle period kept constant when the alternate heating mode is performed.
Fig. 13 is diagrams of an appearance configuration of the induction heating device of the second embodiment according to this disclosure and (a) on the upper side is a plane view while (b) on the lower side is a vertical cross-sectional view taken in the substantially center portion of the first heating coil 6 disposed closer to a user.
the induction heating device of the second embodiment has the first heating coil 6 and the second heating coil 7 arranged under the top plate 18 made of crystallized glass etc. Loads of different materials and shapes are placed on the first heating coil 6 and the second heating coil 7, and necessary powers are supplied to the respective heating coils 6, 7 in accordance with an operation from the operation/display part 17 in this configuration.
the induction heating device of the second embodiment generates no interference sound even when being operated by the control part 13 at an optimum operation frequency depending on a material of a load and a necessary power set by a user.
a loss is reduced in the first to third semiconductor switches 10, 11, 12 in the induction heating device of the second embodiment and this configuration has advantages such as that cooling components including a radiation fin can be miniaturized.
Fig. 14 is diagrams of another configuration example of the induction heating device of the second embodiment according to this disclosure.
the induction heating device depicted in Fig. 14 has the first heating coil 6 and the second heating coil 7 in an oval shape arranged under the one heating region H indicated on the top plate 18 made of crystallized glass etc., and is configured such that one load such as a pot can be heated by the two heating coils 6, 7 at the same time.
the oval heating coils 6, 7 are arranged in parallel such that the major axes are located on lines extending from the user side toward a back surface of the device.
(a) on the upper side is a plane view and (b) on the lower side is a vertical cross-sectional view taken in the substantially center portions of the first heating coil 6 and the second heating coil 7.
the induction heating device depicted in Fig. 14 can perform the heating without the interference sound regardless of the placement state of the pot. In this case, only the necessary heating coil can be energized depending on a shape, an amount, etc. of the load and, therefore, the heating can efficiently be performed in this configuration.
a plurality of resonance circuits made up of heating coils inductively heating a load and resonance capacitors are connected to three serially-connected semiconductor switches and, while one semiconductor switch of the three semiconductor switches is in the constantly conductive state (on-state) as a semiconductor switch determining a heating coil supplied with power, the alternate heating mode is used in which the remaining semiconductor switches are used as semiconductor switches controlled to the conductive state/non-conductive state (on/off-state) for supplying the high-frequency power to the heating coils.
the induction heating device of the second embodiment generates no interference sound even when supplying the high-frequency power to a plurality of the heating coils by switching the heating coils supplied with the power at high speed, and has excellent cooking performance.
the configuration of the second embedment has the reduced number of components and therefore can achieve an inexpensive induction heating device with a small circuit mounting area.
Fig. 15 is a diagram of a circuit configuration of the induction heating device of the third embodiment.
the induction heating device of the third embodiment has the similar circuit configuration as the induction heating device of the first embodiment described above, and is made up of the AC power source 1; the rectification circuit 2; the smoothing circuit 30; the series connection body of the first to third semiconductor switches 10, 11, 12; a series connection body of the first heating coil 6 and the first resonance capacitor 8; a series connection body of the second heating coil 7 and the second resonance capacitor 9; the input current detecting part 3; and the control part 13.
the first to third semiconductor switches 10, 11, and 12 are made up of power semiconductors (semiconductor switch elements), such as IGBTs or MOSFETs, and diodes connected in parallel to the respective power semiconductors in the opposite direction.
a snubber capacitor suppressing a rapid voltage rise at the time of shift from the on-state to the off-state may be connected in parallel between a collector and an emitter of the first to third semiconductor switches 10, 11, and 12.
a snubber capacitor is connected in parallel between the collector and the emitter of the first semiconductor switch 10 and the third semiconductor switch 12.
the induction heating device of the third embodiment configured as described above is configured such that a plurality of heating coils heats loads of substantially the same material, and is particularly used when a single load is heated by a plurality of heating coils.
the induction heating device of the third embodiment in the case of configuration of the two heating coils 6 and 7, the two heating coils 6 and 7 are arranged substantially concentrically in one heating region.
the two heating coils 6 and 7 having an oval shape as a planar shape are arranged adjacently in one heating region.
the configuration of the induction heating device of the third embodiment includes a configuration of heating one load by using a plurality of heating coils having respective different centers of circles. Therefore, as depicted in Fig.
the configuration of the induction heating device of the third embodiment includes a configuration in which a plurality of the heating coils 6, 7 is arranged on an almost entire area of the top plate in a matrix shape to heat one load with a plurality of the heating coils 6, 7.
the operation frequencies of the high-frequency powers supplied to the loads 25 are respectively different in most cases.
a difference in the operation frequencies is in the audible range in such case, an interference sound attributable to the operation frequency difference is generated and a user feels that a noise is loud. Therefore, a configuration must be achieved that enables the heating operation performed with the operation frequency kept in a constant state even when the material of the load 25 is changed, so as not to generate the interference sound.
the inductance values of the first heating coil 6 and the second heating coil 7 for heating the one load 25 depicted in Figs. 16 to 18 are desirably set to substantially the same value so that the electric power amounts are hardly biased.
Fig. 19 is a waveform diagram of an operation state of the simultaneous heating mode in the induction heating device of the third embodiment.
Fig. 19 includes (a) to (c) as gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, (d) as a current waveform of the first heating coil 6, and (e) as a current waveform of the second heating coil 7.
the control part 13 puts the second semiconductor switch (Q1b) 11 into the constantly conductive state and controls the conductive state/non-conductive state (on-state/off-state) of the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12.
the control of putting the first semiconductor switch (Q1a) 10 into the conductive state (on-state) and putting the third semiconductor switch (Q1c) 12 into the non-conductive state (off-state) simultaneously generates the mode of supplying a power to the second heating coil 7 through the path from the smoothing capacitor 5 ⁇ the first semiconductor switch (Q1a) 10 ⁇ the second semiconductor switch (Q1b) 11 ⁇ the second heating coil 7 ⁇ the second resonance capacitor 9, and the mode of supplying a power to the first heating coil 6 through the path from the first resonance capacitor 8 ⁇ the first semiconductor switch (Q1a) 10 ⁇ the first heating coil 6.
the control part 13 puts only the first semiconductor switch (Q1a) 10 into the non-conductive state at the conduction time when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section A). After a predetermined transition time (section X) has elapsed from the termination of the section A, the control part 13 puts the third semiconductor switch (Q1c) 12 into the conductive state.
this simultaneously generates the operation of supplying a power to the first heating coil 6 through the path from the smoothing capacitor 5 ⁇ the first resonance capacitor 8 ⁇ the first heating coil 6 ⁇ the second semiconductor switch (Q1b) 11 ⁇ the third semiconductor switch (Q1c) 12, and the operation of supplying a power to the second heating coil 7 through the path from the second resonance capacitor 9 ⁇ the second heating coil 7 ⁇ the third semiconductor switch (Q1c) 12.
the control part 13 puts only the third semiconductor switch (Q1c) 12 into the non-conductive state at the conduction time (section B) when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section B). After the termination of the section B, when the predetermined transition time (section Y) has elapsed, the control part 13 puts the first semiconductor switch (Q1a) 10 into the conductive state again.
the control part 13 can put the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12 alternately into the conductive state while keeping the second semiconductor switch (Q1b) 11 in the conductive state, thereby supplying a high-frequency current of about 20 kHz to 60 kHz to both the first heating coil 6 and the second heating coil 7 at the same time.
a desired high-frequency magnetic field generated from the heating coils supplied with the high-frequency current is supplied to the load such as a pot.
the induction heating device of the third embodiment is configured such that the alternate heating mode can be performed.
Fig. 20A is a waveform diagram of the first single heating mode in which high-frequency power is supplied to the second heating coil 7.
Fig. 20A includes (a) to (c) depicting gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, and (d) depicting a current waveform of the second heating coil 7.
the control part 13 puts the first semiconductor switch (Q1a) 10 into a constantly conductive state and controls a conductive state/non-conductive state (on-state/off-state) of the second semiconductor switch (Q1b) 11 and the third semiconductor switch (Q1c) 12.
the control part 13 puts the second semiconductor switch (Q1b) 11 into the conductive state (on-state) and the third semiconductor switch (Q1c) 12 into the non-conductive state (off-state).
the power is supplied to the second heating coil 7 through the path from the smoothing capacitor 5 ⁇ the first semiconductor switch (Q1a) 10 ⁇ the second semiconductor switch (Q1b) 11 ⁇ the second heating coil 7 ⁇ the second resonance capacitor 9.
the control part 13 puts only the second semiconductor switch (Q1b) 11 into the non-conductive state at the conduction time (Tb) when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section A). After a predetermined transition time (section X) has elapsed from the termination of the section A, the control part 13 puts the third semiconductor switch (Q1c) 12 into the conductive state. As a result, the power is supplied to the second heating coil 7 through the path from the second resonance capacitor 9 ⁇ the second heating coil 7 ⁇ the third semiconductor switch 12. Subsequently, the control part 13 puts the third semiconductor switch (Q1c) 12 into the non-conductive state at the conduction time (Tc) when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section B).
control part 13 puts the second semiconductor switch (Q1b) 11 into the conductive state (section A). As described above, the control part 13 allows the operations of the section A and the section B to continue alternately via the transmission time (X or Y).
control part 13 can put the second semiconductor switch (Q1b) 11 and the third semiconductor switch (Q1c) 12 alternately into the conductive state while keeping the first semiconductor switch (Q1a) 10 in the conductive state, thereby supplying a high-frequency current of about 20 kHz to 60 kHz to the second heating coil 7.
the high-frequency magnetic field generated from the second heating coil 7 due to the high-frequency current supplied in this way is supplied to the load such as a pot.
the high-frequency magnetic field supplied to the load such as a pot in this way generates an eddy current on a surface of the load such as a pot, and the load such as the pot is inductively heated due to the eddy current and a high-frequency resistance of the load such as a pot itself, which leads to heat generation.
the second single heating mode of supplying high-frequency power to the first heating coil 6 will be described with reference to Fig. 20B .
the control part 13 puts the third semiconductor switch (Q1c) 12 into the constantly conductive state and controls the conductive state/non-conductive state (on-state/off-state) of the first semiconductor switch (Q1a) 10 and the second semiconductor switch (Q1b) 11.
the control part 13 puts the second semiconductor switch (Q1b) 11 into the conductive state in the section A depicted in Fig. 20B , the power is supplied to the first heating coil 6 through the path from the smoothing capacitor 5 ⁇ the first resonance capacitor 8 ⁇ the first heating coil 6 ⁇ the second semiconductor switch (Q1b) 11 ⁇ the third semiconductor switch (Q1c) 12.
the control part 13 puts only the second semiconductor switch (Q1b) 11 into the non-conductive state at the conduction time (Tb) when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section A).
the control part 13 puts the first semiconductor switch (Q1a) 10 into the conductive state.
the power is supplied to the first heating coil 6 through the path from the first resonance capacitor 8 ⁇ the first semiconductor switch (Q1a) ⁇ the first heating coil 6.
the control part 13 puts the first semiconductor switch (Q1a) 10 into the non-conductive state at the conduction time (Ta) when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section B).
the control part 13 puts the second semiconductor switch (Q1b) 11 into the conductive state (section A).
the control part 13 allows the operations of the section A and the section B to continue via the transmission time (X or Y).
the control part 13 can put the first semiconductor switch (Q1a) 10 and the second semiconductor switch (Q1b) 11 alternately into the conductive state while keeping the third semiconductor switch (Q1c) 12 in the conductive state, thereby supplying a high-frequency current of about 20 kHz to 60 kHz to the first heating coil 6.
the high-frequency magnetic field generated from the heating coil due to the high-frequency current supplied in this way is supplied to the load such as a pot.
Fig. 21 is a waveform diagram of an operation of the alternate heating mode in the induction heating device of the third embodiment.
the alternate heating mode is the operation when the first single heating mode depicted in Fig. 20A and the second single heating mode depicted in Fig. 20B are alternately used for heating a plurality of loads.
Fig. 21 includes (a) to (c) as gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, (d) as a current waveform of the second heating coil 7, and (e) as a current waveform of the first heating coil 6.
an operation time of the first single heating mode is T2 and an operation time of the second single heating mode is T1. Therefore, in the third embodiment, each of the operation time T1 and the operation time T2 is set to a very short time within one second and one cycle (T1+T2) of the alternate heating mode is set to two seconds or less.
the same control is provided as the control described with reference to Fig. 10 in the second embodiment and the highly efficient switchover operation is performed in a short time.
the loads in the alternate heating mode, can simultaneously be heated without deteriorating the heating distribution for the loads by periodically operating the first single heating mode and the second single heating mode alternately in a short period of time.
the induction heating device of the third embodiment can reduce heating unevenness for the loads without lowering the average power by setting a short switchover time equal to or less than two seconds between the first single heating mode and the second single heating mode.
Fig. 22 is a diagram of a relationship between the conduction time of the semiconductor switch and the resonance voltage generated in the resonance capacitor depending on a material of a load.
the resonance frequency varies depending on a material of a load in the resonance circuit made up of the first resonance capacitor 8 and the first heating coil 6 magnetically coupled to the load, or the resonance circuit made up of the second resonance capacitor 9 and the second heating coil 7 magnetically coupled to the load.
the inductance While no load exists, the inductance is the largest and the resonance frequency becomes lower. On the other hand, when a load is disposed in the vicinity of the heating coil and the load is magnetically coupled to the heating coil, the inductance is reduced and the resonance frequency becomes higher.
the inductance is reduced in the load 25B made of non-magnetic stainless steel etc., as compared to the load 25A made of iron, stainless steel, etc., and therefore, the resonance frequency is increased. If a load has intermediate characteristics between magnetic stainless steel and non-magnetic stainless steel, the resonance frequency is between those of the both stainless steels.
the control part 13 can determine a type of a load by detecting a resonance voltage generated at predetermined operation frequency and conduction time.
a load 25B having a low inductance and an operation frequency close to the resonance frequency makes the resonance voltage higher, while a load 25A having characteristics of a high inductance and an operation frequency far from the resonance frequency makes the resonance voltage lower.
the resonance voltage becomes lower in the order of the load 25B, the load 25A, and no load. Therefore, a type of a load and the presence/absence of a load can be determined by detecting the resonance voltage generated at predetermined operation frequency and conduction time.
the operation frequency is kept constant for preventing the inference sound with an adjacent load in the configuration of the third embodiment, a large difference is generated in the input power generated during the conduction time depending on a material of a load as depicted in Fig. 23 . Therefore, since the input power cannot sufficiently be reduced for some loads and a control width of power control must be increased, the heating device may have poor usability.
the device in the case of a load having characteristics of a high inductance and an operation frequency sufficiently far from the resonance frequency, for example, in the case of the load 25A made of a magnetic material, the device is operated in the simultaneous heating mode (see Fig. 19 ) that is the operation in which the first heating coil 6 and the second heating coil 7 are connected in parallel.
the device in the case of a load having characteristics of a low inductance and an operation frequency close to the resonance frequency so that the input power is easily introduced, for example, in the case of the load 25B made of a non-magnetic material, the device is operated in the alternate heating mode (see Figs.
the impedance of the heating coils connected to the semiconductor switches is doubled and, as a result, the current to the heating coils can be suppressed to reduce the input power.
a plurality of resonance circuits made up of heating coils inductively heating a load and resonance capacitors are connected to three serially-connected semiconductor switches in the induction heating device configured to use a plurality of the heating coils to heat the same load and, in the case of a load of a load material making an equivalent resistance value larger, the device is operated in the simultaneous heating mode (see Fig. 19 ) in which the first and third semiconductor switches are alternately made conductive while the second semiconductor switch is made always conductive so as to supply power to the first heating coil and the second heating coil at the same time.
the device is operated in the alternate heating mode (see Figs. 20A and 20B ) by alternately repeating the operations in a short cycle between the first single heating mode in which the second and third semiconductor switches are alternately made conductive while the first semiconductor switch is made always conductive so as to supply high-frequency power to the second heating coil and the second single heating mode in which the first and second semiconductor switches are alternately made conductive while the third semiconductor switch is made always conductive so as to supply high-frequency power to the first heating coil.
the heating control is provided as described above in the induction heating device of the third embodiment, a predetermined input power can be applied at a constant frequency to a load even when a type of the load is changed, and the induction heating device generating no interference sound and excellent in controllability can be achieved.
the configuration of the induction heating device of the fourth embodiment has the same configuration as the induction heating devices of the first to third embodiments and is different in a method of controlling the heating operation for the heating coils.
the induction heating device of the fourth embodiment has a mode of heating a plurality of heating coils in the simultaneous heating mode and this simultaneous heating mode is the same operation as the simultaneous heating mode described with reference to Fig. 19 in the third embodiment described above.
the induction heating device of the fourth embodiment has a step-down simultaneous heating mode described later in addition to the simultaneous heating mode.
Fig. 24 is a waveform diagram of an operation state of the step-down simultaneous heating mode in the induction heating device of the fourth embodiment.
Fig. 24 includes (a) to (c) as gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, (d) as a current waveform of the first heating coil 6, and (e) as a current waveform of the second heating coil 7.
the control part 13 controls the conductive state/non-conductive state (on-state/off-state) of the first semiconductor switch (Q1a) 10, the second semiconductor switch (Q1b) 11, and the third semiconductor switch (Q1c) 12.
the control part 13 puts the first semiconductor switch (Q1a) 10 into the non-conductive state (off-state), the second semiconductor switch (Q1b) 11 into the conductive state (on-state), and the third semiconductor switch (Q1c) 12 into the non-conductive state (off-state), the power is supplied to the first heating coil 6 and the second heating coil 7 through the path from the smoothing capacitor 5 ⁇ the first resonance capacitor 8 ⁇ the first heating coil 6 ⁇ the second semiconductor switch (Q1b) 11 ⁇ the second heating coil 7 ⁇ the second resonance capacitor 9.
the series circuit of the first heating coil 6 and the first resonance capacitor 8 and the series circuit of the second heating coil 7 and the second resonance capacitor 9 are connected to the smoothing capacitor 5 in series. Therefore, a divided voltage is applied to each of the series circuits and, particularly when each of the series circuits has substantially the same circuit constant, an approximately 1/2 voltage is applied.
the control part 13 puts the second semiconductor switch (Q1b) 11 into the non-conductive state at the conduction time when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section B). After the predetermined transition time (section Y) has elapsed from the termination of the section B, the control part 13 puts the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12 into the conductive state (section A).
this simultaneously generates the operation of supplying a power to the first heating coil 6 through the path from the first resonance capacitor 8 ⁇ the first semiconductor switch (Q1a) 10 ⁇ the first heating coil 6, and the operation of supplying a power to the second heating coil 7 through the path from the second resonance capacitor 9 ⁇ the second heating coil 7 ⁇ the third semiconductor switch (Q1c) 12.
the control part 13 puts the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12 into the non-conductive state at the conduction time (section A) when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section A). After the predetermined transition time (section X) has elapsed from the termination of the section A, the control part 13 puts the second semiconductor switch (Q1b) 11 into the conductive state again (section B).
the control part 13 can put the second semiconductor switch (Q1b) 11 and a set of the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12 alternately into the conductive state/non-conductive state, thereby supplying a high-frequency current of about 20 kHz to 60 kHz to both the first heating coil 6 and the second heating coil 7 at the same time.
a desired high-frequency magnetic field generated from the heating coils supplied with the high-frequency current is supplied to the load such as a pot.
control part 13 in the induction heating device of the fourth embodiment also has a configuration capable of determining a type of a load coupled to the heating coils and the presence/absence of the load by detecting a resonance voltage generated at predetermined operation frequency and conduction time.
the operation frequency is kept constant for preventing the inference sound with an adjacent load in the configuration of the fourth embodiment, a large difference is generated in the input power generated during the conduction time depending on a material of a load as is the case with the third embodiment (see Fig. 23 ). Therefore, the input power cannot sufficiently be reduced for some loads and the heating device may have poor usability because of an increased control width of power control etc.
the device in the case of the load 25A having characteristics of a high inductance and an operation frequency sufficiently far from the resonance frequency, the device is operated in the simultaneous heating mode that is the operation in which the first heating coil 6 and the second heating coil 7 are connected in parallel.
the device in the case of the load 25B having characteristics of a low inductance and an operation frequency close to the resonance frequency so that the input power is easily introduced, the device is operated in the step-down simultaneous heating mode in which the voltage applied to each of the first heating coil 6 and the second heating coil 7 is reduced (by 1/2 under the same conditions).
the input power can sufficiently be reduced. If the voltage applied to each of the heating coils is reduced by 1/2, the power becomes 1/4 under the same operation conditions (the operation frequency and the conduction time).
the induction heating device of the fourth embodiment may be in a configuration having the alternate heating mode ( Figs. 20A and 20B ) described in the third embodiment. If a load is inductively heated under the same operation conditions (the operation frequency and the conduction time) in the configuration having the simultaneous heating mode, the step-down simultaneous heating mode, and the alternate heating mode, the magnitude of the input power often becomes smaller in the order of the simultaneous heating mode, the alternate heating mode, and the step-down simultaneous heating mode.
a method of selecting a suitable heating mode for a load can be implemented by sequentially switching the three heating modes in the order of the simultaneous heating mode, the alternate heating mode, and the step-down simultaneous heating mode depending on a condition such as a material of the load.
a plurality of resonance circuits made up of heating coils inductively heating a load and resonance capacitors are connected to three serially-connected semiconductor switches in the induction heating device configured to use a plurality of the heating coils to heat the same load and, in the case of a load of a load material making an equivalent resistance value larger, the device is operated in the simultaneous heating mode in which the first and third semiconductor switches are alternately made conductive while the second semiconductor switch is made always conductive so as to supply power to the first heating coil and the second heating coil at the same time.
the device in the case of a load of a material making an equivalent resistance value smaller, the device is operated in the step-down simultaneous heating mode in which the second semiconductor switch and a set of the first semiconductor switch and the third semiconductor switch are alternately made conductive to supply the high-frequency power to the first heating coil and the second heating coil at the same time while the voltage applied to the heating coils can be reduced.
the heating control is provided as described above in the induction heating device of the fourth embodiment, a predetermined input power can be applied at a constant frequency to a load even when a type of the load is changed, and the induction heating device generating no interference sound and excellent in controllability can be achieved.
Fig. 25 is a diagram of a circuit configuration of the induction heating cooker of the fifth embodiment according to this disclosure.
the induction heating device of the fifth embodiment is different from the induction heating devices of the third embodiment and the fourth embodiment described above in that the first heating coil 6 is made up of a heating coil group of first heating coil elements 6a, 6b, 6c and that the second heating coil 7 is made up of a heating coil group of second heating coil elements 7a, 7b, 7c.
the respective heating coil elements 6a, 6b, 6c are connected to first resonance capacitor elements 8a, 8b, 8c making up the first resonance capacitor 8 and first opening/closing part elements 20a, 20b, 20c making up a first opening/closing part 20 in series.
the respective heating coil elements 7a, 7b, 7c are connected to second resonance capacitor elements 9a, 9b, 9c making up the second resonance capacitor 9 and second opening/closing part elements 21a, 21b, 21c making up a second opening/closing part 21 in series.
the induction heating device of the fifth embodiment is disposed with a load detecting part 22 detecting the presence of a load in the vicinity of the heating coil elements 6a, 6b, 6c and the heating coil elements 7a, 7b, 7c, which is another difference from the induction heating devices of the third embodiment and the fourth embodiment described above.
each heating coil may be made up of two or more heating coil elements and the number of heating coil elements is not particularly limited in this disclosure.
the first opening/closing part elements 20a to 20c making up the first opening/closing part 20 and the second opening/closing part elements 21a to 21c making up the second opening/ closing part 21 may have any configurations, such as those of electromagnetic relays and semiconductor switches, capable of operations for connecting/disconnecting the heating coil elements to/from a power source circuit, and the configurations of the opening/closing part elements are not particularly limited in this disclosure.
the control part 13 When receiving a command for an operation start from an operation part not depicted, the control part 13 first puts the first opening/closing part elements 20a to 20c and the second opening/ closing part elements 21a to 21c into a closed state and applies to the heating coils a predetermined high-frequency current smaller than a high-frequency current during the heating operation to detect whether a load is present in the vicinity of the heating coils with the load detecting part 22.
the load detecting part 22 determines the presence of a load and a material of a load from control values such as a conduction time and an operation frequency from the control part 13 as well as voltage values of the resonance capacitors, current values of the heating coil elements, a current value detected by the input current detecting part 3, etc.
the control part 13 puts the opening/closing part element connected to the heating coil element into an opened state to open the connection state to the first semiconductor switch 10 or the third semiconductor switch 12.
the control part 13 puts the opening/closing part element connected to the heating coil element into a closed state to achieve the connection state to the first semiconductor switch 10 or the third semiconductor switch 12.
the control part 13 selects an appropriate heating mode from the simultaneous heating mode, the alternate heating mode, and the step-down simultaneous heating mode depending on the number of the heating coil elements having the opening/closing part elements connected and operates the semiconductor switches in accordance with the selected heating mode.
the number of the connected heating coil elements depends on a shape of the load and, therefore, when the load has a larger shape, the heating operation is performed by using a larger number of the heating coils.
the induction heating device of the fifth embodiment can achieve favorable heating distribution and can improve the cooking performance.
Fig. 26 is a diagram of characteristics of input power in the heating modes to the conduction time. As depicted in Fig. 26 , the induction heating device of the fifth embodiment is operated in the simultaneous heating mode when a load of a single material is heated by two heating coil elements.
a load of substantially the same material having a larger shape is heated, for example, if a load is heated by four heating coil elements, and the device is operated in the simultaneous heating mode, the impedance of the heating coil elements connected in parallel and coupled to the load is reduced by approximately 1/2 as compared to when the load is heated by two heating coils. Therefore, when the load is heated by four heating coil elements, this results in an increase in input power for the same conduction time as compared to when the load is heated by two heating coils.
the case of heating by four heating coil elements causes problems such as that the control part 13 cannot reduce the power to the necessary input power or cannot provide proper power control under the condition of a constant operation frequency because of deterioration in resolving power. Therefore, for example, in the case of heating by four heating coil elements, the alternate heating mode is used for reducing the number of the heating coil elements connected in parallel to the load when being operated at the same time.
the induction heating device of the fifth embodiment is configured to be operated depending on the number of the connected heating coil elements supplied with the high-frequency power so as not to reduce the impedance of the heating coils parallel to the load, such that the characteristics of the input power to the conduction time are not changed.
the characteristics of the input power to the conduction time can be changed depending on the number of the connections of the heating coil elements by using the step-down simultaneous heating mode.
the induction heating device of the fifth embodiment can be operated by selecting any heating mode of the simultaneous heating mode, the alternate heating mode, and the step-down simultaneous heating mode depending on the number of the connections of the heating coil elements forming the first heating coil and the second heating coil supplied with the high-frequency power so as to apply a predetermined input power to the load at a constant frequency even when the number of the heating coil elements to be driven is changed, and the induction heating device generating no interference sound and excellent in controllability can be achieved.
Fig. 27 is a diagram of a circuit configuration of the induction heating device of the sixth embodiment according to this disclosure.
the induction heating device of the sixth embodiment is made up of the AC power source 1; the rectification circuit 2; the smoothing circuit 30 made up of the choke coil 4 and the smoothing capacitor 5; and the series connection body of the first semiconductor switch 10, the second semiconductor switch 11, and the third semiconductor switch 12 connected in parallel to the smoothing capacitor 5.
the induction heating device of the sixth embodiment has a series connection body of the first heating coil 6, the first resonance capacitor 8, and the first opening/closing part 20 connected in parallel to the first semiconductor switch 10, and a series connection body of the second heating coil 7, the second resonance capacitor 9, and the second opening/closing part 21 connected in parallel to the third semiconductor switch 12.
the first heating coil 6 is made up of a heating coil group of a plurality of first heating coil elements 6a, 6b, 6c, 6d
the second heating coil 7 is made up of a heating coil group of a plurality of second heating coil elements 7a, 7b, 7c, 7d.
the respective heating coil elements 6a, 6b, 6c, 6d are connected to first resonance capacitor elements 8a, 8b, 8c, 8d making up the first resonance capacitor 8 and first opening/closing part elements 20a, 20b, 20c, 20d making up a first opening/closing part 20 in series.
the respective heating coil elements 7a, 7b, 7c, 7d are connected to second resonance capacitor elements 9a, 9b, 9c, 9d making up the second resonance capacitor 9 and second opening/closing part elements 21a, 21b, 21c, 21d making up a second opening/closing part 21 in series.
the induction heating device of the sixth embodiment further has the load detecting part 22 detecting whether a heatable load is present in the vicinity of each of the heating coil elements, the input current detecting part 3 detecting a current flowing from the AC power source 1 to the rectification circuit 2 with a current transformer etc., and the control part 13 controlling the first to third semiconductor switches 10, 11, and 12 such that a detection value of the input current detecting part 3 becomes equal to a set value, and controlling the opened/closed states of the first opening/closing part 20 and the second opening/closing part 21 in accordance with a detection value of the load detecting part 22.
each heating coil may be made up of two or more heating coil elements and the number of heating coil elements is not particularly limited in this disclosure.
the target values of the control part 13 include the current and voltage of the heating coils in addition to the input current, and are not particularly limited in the configuration of the sixth embodiment.
the first to third semiconductor switches 10, 11, and 12 are made up of power semiconductors (semiconductor switch elements), such as IGBTs or MOSFETs, and diodes connected in parallel to the respective power semiconductors in the opposite direction.
a snubber capacitor suppressing a rapid voltage rise at the time of shift from the on-state to the off-state may be connected in parallel between a collector and an emitter of the first to third semiconductor switches 10, 11, and 12.
a snubber capacitor is connected in parallel between the collector and the emitter of the first semiconductor switch 10 and the third semiconductor switch 12.
Figs. 28 and 29 are plane views of configurations in which a plurality of the heating coil elements making up the heating coil groups is arranged in a matrix shape.
a plurality of the heating coil elements is arranged longitudinally and laterally in lattice in a region except an operation/display part 16 disposed closer to a user in a region under a top plate 15 on which a load is placed.
the induction heating device of the sixth embodiment configured as described above, for example, when a small load 14a with a pot bottom in a circular shape is placed on the top plate 15 as depicted in Fig. 28 , the first heating coil 6 is formed by the two heating coil elements 6b, 6c while the second heating coil 7 is formed by the two heating coil elements 7b, 7c, and the high-frequency current is supplied only to each of the heating coil elements 6b, 6c, 7b, 7c,.
the high-frequency current is supplied to more corresponding heating coil elements.
the load can efficiently be heated with favorable heating distribution.
the planar shape of the heating coil elements considering that a load with a pot bottom diameter of ⁇ 160 to ⁇ 240 mm is heated by a plurality of heating coil elements, it is desirable that the diameter of the circle of the planar shape is about ⁇ 30 to ⁇ 120 mm.
the planar shape of the heating coil elements is not particularly limited to the shape described above.
the heating coil elements are arranged to form a staggered grid so as to arrange the heating coil elements as dense as possible. Therefore, in an arrangement configuration depicted in Fig. 29 , a plurality of the heating coil elements are arranged on longitudinal lines extended from the side closer to a user (closer to the operation/display part) toward the back surface and the heating coil elements on the adjacent longitudinal lines are staggered. In the case of this arrangement configuration, a gap between the heating coil elements decreases although the number of the heating coil elements increases. Therefore, more favorable heating distribution can be acquired as compared to the arrangement configuration depicted in Fig. 28 .
the heating coil elements are desirably have the inductance values set to substantially the same value and the same shape so as to avoid a bias in the electric power amount.
the operation frequency is made higher in the case of heating the load 14b heated by a large number of the heating coil elements so as to reduce the input power.
the load 14a heated by a small number of the heating coil elements is heated along with the load 14b heated by a large number of the heating coil elements at the same time, a frequency difference occurs between the respective operation frequencies, and the interference sound occurs.
the control part 13 in the induction heating device of the sixth embodiment changes the heating mode depending on the number of the connections of the heating coil elements used in the case of heating the load.
the control part 13 controls the conduction states of the first semiconductor switch 10, the second conductive switch 11, and the third conductive switch 12 to the states adapted to the respective heating modes.
the control part 13 can change the conduction states of the semiconductor switches 10, 11, 12 depending on the number of the connected heating coils so as to change the voltage applied to the first heating coil 6 and the second heating coil 7.
the power control can be provided with the operation frequency kept constant.
the control part 13 detects whether a load is present on the top plate 15 with the load detecting part 22.
the load detecting part 22 operates the semiconductor switches and uses the current and voltage generated in the heating coil elements and the detection values of the input current detecting part 3.
Fig. 30 depicts an example of a load detection method and is a diagram of a relationship between a conduction time of a semiconductor switch and a resonance voltage generated in a resonance capacitor depending on a material of a load.
the resonance frequency varies depending on a material of a load in the resonance circuit made up of the heating coil elements magnetically coupled to a load and the resonance capacitor. While no load exists, the inductance is the largest and the resonance frequency becomes lower.
the inductance when a load is disposed in the vicinity of the heating coil and the load is magnetically coupled to the heating coil, the inductance is reduced and the resonance frequency becomes higher.
the inductance is reduced in the load 14b made of non-magnetic stainless steel etc., as compared to the load 14a made of magnetic stainless steel, etc., and therefore, the resonance frequency is increased.
the control part 13 can determine a type of a load by detecting a resonance voltage generated at predetermined operation frequency and conduction time.
the load 14b having an operation frequency close to the resonance frequency makes the resonance voltage higher, while the load 14a having a lower operation frequency far from the resonance frequency makes the resonance voltage lower.
the detection value of the resonance voltage becomes lower in the order of the load 14b, the load 14a, and no load. Therefore, a material of a load can be determined by detecting the resonance voltage generated at predetermined operation frequency and conduction time.
the heating coil elements put together by a load placed thereon at substantially the same time are determined as having the same load placed thereon, and the corresponding first and second opening/closing part elements are put into the closed state to connect the respective heating coil elements having a detected load to the first semiconductor switch 10 and the third semiconductor switch 12.
the control part 13 performs the operation of the simultaneous heating mode or the alternate heating mode depending on the number of connections of the heating coil elements.
Fig. 31 is a waveform diagram of an operation state of the simultaneous heating mode in the induction heating device of the sixth embodiment.
Fig. 31 includes (a) to (c) as gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, (d) as a current waveform of the heating coil elements in the first heating coil 6, and (e) as a current waveform of the heating coil elements of the second heating coil 7.
the control part 13 puts the second semiconductor switch (Q1b) 11 into the constantly conductive state and controls the conductive state/non-conductive state (on-state/off-state) of the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12.
the control of putting the first semiconductor switch (Q1a) 10 into the conductive state (on-state) and putting the third semiconductor switch (Q1c) 12 into the non-conductive state (off-state) simultaneously generates the operation of supplying a power to the second heating coil 7 (the corresponding second heating coil elements) through the path from the smoothing capacitor 5 ⁇ the first semiconductor switch 10 ⁇ the second semiconductor switch (Q1b) 11 ⁇ the second heating coil 7 (the corresponding second heating coil elements) ⁇ the second resonance capacitor 9 (the corresponding second resonance capacitor elements) ⁇ the second opening/closing part 21 (the corresponding second opening/closing part elements), and the operation of supplying a power to the first heating coil 6 (the corresponding first heating coil elements) through the path from the first resonance capacitor 8 (the corresponding first resonance capacitor elements) ⁇ the first opening/closing part 20 (the corresponding first opening/closing part elements) ⁇ the first semiconductor switch (Q1a) 10 ⁇ the first
the control part 13 puts only the first semiconductor switch (Q1a) 10 into the non-conductive state at the conduction time when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section A). After a predetermined transition time (section X) has elapsed from the termination of the section A, the control part 13 puts the third semiconductor switch (Q1c) 12 into the conductive state.
this simultaneously generates the operation of supplying a power to the first heating coil 6 (the corresponding first heating coil elements) through the path from the smoothing capacitor 5 ⁇ the first opening/closing part 20 (the corresponding first opening/closing part elements) ⁇ the first resonance capacitor 8 (the corresponding first resonance capacitor elements) ⁇ the first heating coil 6 (the corresponding first heating coil elements) ⁇ the second semiconductor switch (Q1b) 11 ⁇ the third semiconductor switch (Q1c) 12, and the operation of supplying a power to the second heating coil 7 (the corresponding second heating coil elements) through the path from the second resonance capacitor 9 (the corresponding second resonance capacitor elements) ⁇ the second heating coil 7 (the corresponding second heating coil elements) ⁇ the third semiconductor switch (Q1c) 12 ⁇ the second opening/closing part 21 (the corresponding second opening/closing part elements).
the control part 13 puts only the third semiconductor switch (Q1c) 12 into the non-conductive state at the conduction time (section B) when the current value detected by the input current detecting part 3 indicates the predetermined current value. After the termination of the section B, when the predetermined transition time (section Y) has elapsed, the control part 13 puts the first semiconductor switch (Q1a) 10 into the conductive state again.
the control part 13 puts the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12 alternately into the conductive state while keeping the second semiconductor switch (Q1b) 11 in the conductive state, thereby supplying a high-frequency current of about 20 kHz to 60 kHz to the corresponding heating coil elements in the first heating coil 6 and the second heating coil 7 at the same time, and the high-frequency magnetic field generated from the corresponding heating coil elements due to the high-frequency current is supplied to the load such as a pot.
the induction heating device of the sixth embodiment is configured such that the alternate heating mode can be performed.
Fig. 32A is a waveform diagram of the first single heating mode in which high-frequency power is supplied to the corresponding second heating coil elements in the second heating coil 7.
Fig. 32A includes (a) to (c) depicting gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, and (d) depicting a current waveform of the second heating coil 7.
the control part 13 puts the first semiconductor switch (Q1a) 10 into the constantly conductive state and controls a conductive state/non-conductive state (on-state/off-state) of the second semiconductor switch (Q1b) 11 and the third semiconductor switch (Q1c) 12.
the control part 13 puts the second semiconductor switch (Q1b) 11 into the conductive state (on-state) and the third semiconductor switch (Q1c) 12 into the non-conductive state (off-state).
the power is supplied to the second heating coil 7 (the corresponding second heating coil elements) through the path from the smoothing capacitor 5 ⁇ the first semiconductor switch (Q1a) 10 ⁇ the second semiconductor switch (Q1b) 11 ⁇ the second heating coil 7 (the corresponding second heating coil elements) ⁇ the second resonance capacitor 9 (the corresponding second resonance capacitor elements) ⁇ the second opening/ closing part 21 (the corresponding second opening/closing part elements).
the control part 13 puts only the second semiconductor switch (Q1b) 11 into the non-conductive state at the conduction time (Tb) when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section A). After a predetermined transition time (section X) has elapsed from the termination of the section A, the control part 13 puts the third semiconductor switch (Q1c) 12 into the conductive state.
the power is supplied to the second heating coil 7 (the corresponding second heating coil elements) through the path from the second resonance capacitor 9 (the corresponding second resonance capacitor elements) ⁇ the second heating coil 7 (the corresponding second heating coil elements) ⁇ the third semiconductor switch (Q1c) 12 ⁇ the second opening/closing part 21 (the corresponding second opening/closing part elements).
the control part 13 puts the third semiconductor switch (Q1c) 12 into the non-conductive state at the conduction time (Tc) when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section B).
control part 13 puts the second semiconductor switch (Q1b) 11 into the conductive state (section A). As described above, the control part 13 allows the operations of the section A and the section B to continue alternately via the transmission time (X or Y).
the control part 13 puts the second semiconductor switch (Q1b) 11 and the third semiconductor switch (Q1c) 12 alternately into the conductive state while keeping the first semiconductor switch (Q1a) 10 in the conductive state, thereby supplying a high-frequency current of about 20 kHz to 60 kHz to the corresponding second heating coil elements in the second heating coil 7 and supplying the high-frequency magnetic field generated from the corresponding second heating coil elements in the second heating coil 7 due to the high-frequency current to the load such as a pot.
the high-frequency magnetic field supplied to the load such as a pot in this way generates an eddy current on a surface of the load such as a pot, and the load such as the pot is inductively heated due to the eddy current and a high-frequency resistance of the load such as a pot itself, which leads to heat generation.
the second single heating mode of supplying high-frequency power to the corresponding heating coil elements in the first heating coil 6 will be described with reference to Fig. 32B .
the control part 13 puts the third semiconductor switch (Q1c) 12 into the constantly conductive state and controls the conductive state/non-conductive state (on-state/off-state) of the first semiconductor switch (Q1a) 10 and the second semiconductor switch (Q1b) 11.
the control part 13 puts the second semiconductor switch (Q1b) 11 into the conductive state in the section A depicted in Fig.
the power is supplied to the first heating coil 6 (the corresponding first heating coil elements) through the path from the smoothing capacitor 5 ⁇ the first opening/closing part 20 (the corresponding first opening/closing part elements) ⁇ the first resonance capacitor 8 (the corresponding first resonance capacitor elements) ⁇ the first heating coil 6 (the corresponding first heating coil elements) ⁇ the second semiconductor switch (Q1b) 11 ⁇ the third semiconductor switch (Q1c) 12.
the control part 13 puts only the second semiconductor switch (Q1b) 11 into the non-conductive state at the conduction time (Tb) when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section A). After the predetermined transition time (section X) has elapsed from the termination of the section A, the control part 13 puts the first semiconductor switch (Q1a) 10 into the conductive state.
the power is supplied to the first heating coil 6 (the corresponding first heating coil elements) through the path from the first resonance capacitor 8 (the corresponding first resonance capacitor elements) ⁇ the first opening/closing part 20 (the corresponding first opening/closing part elements) ⁇ the first semiconductor switch (Q1a) ⁇ the first heating coil 6 (the corresponding first heating coil elements).
the control part 13 puts the first semiconductor switch (Q1a) 10 into the non-conductive state at the conduction time (Ta) when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section B).
control part 13 puts the second semiconductor switch (Q1b) 11 into the conductive state (section A). As described above, the control part 13 allows the operations of the section A and the section B to continue via the transmission time (X or Y).
the control part 13 can put the first semiconductor switch (Q1a) 10 and the second semiconductor switch (Q1b) 11 alternately into the conductive state while keeping the third semiconductor switch (Q1c) 12 in the conductive state, thereby supplying a high-frequency current of about 20 kHz to 60 kHz to the corresponding first heating coil elements in the first heating coil 6.
the high-frequency magnetic field generated from the corresponding second heating coil elements in the first heating coil due to the high-frequency current supplied in this way is supplied to the load such as a pot.
Fig. 33 is a waveform diagram of an operation of the alternate heating mode in the induction heating device of the sixth embodiment.
the alternate heating mode is the operation when the first single heating mode depicted in Fig. 32A and the second single heating mode depicted in Fig. 32B are alternately used for heating a plurality of loads.
Fig. 33 includes (a) to (c) as gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, (d) as a current waveform of the second heating coil 7, and (e) as a current waveform of the first heating coil 6.
an operation time of the first single heating mode is T2 and an operation time of the second single heating mode is T1. Therefore, in the sixth embodiment, each of the operation time T1 and the operation time T2 is set to a very short period within one second and one cycle (T1+T2) of the alternate heating mode is set to two seconds or less.
the same control is provided as the control described with reference to Fig. 10 in the second embodiment and the highly efficient switchover operation is performed in a short time.
the induction heating device of the sixth embodiment can reduce heating unevenness for the loads without lowering the average power by setting a short switchover time generally equal to or less than two seconds between the first single heating mode and the second single heating mode.
the control is provided without any feeling of difference given to a user at the time of alternate heating of a plurality of loads, which is a problem of a conventional induction heating device.
the operation frequency is kept constant for preventing the inference sound with an adjacent load in the configuration of the sixth embodiment, a large difference may be generated in the input power generated during the conduction time depending on the number of heating coil elements supplied with the high-frequency power as depicted in Fig. 34 . Therefore, the input power cannot sufficiently be lowered for some shapes (sizes) of loads and the heating device may have poor usability because of an increased control width of power control etc.
the device in the case of a load associated with a small number of the connected heating coil elements and making the impedance larger, for example, in the case of the first load 14a (the four heating coil elements), the device is operated in the simultaneous heating mode that is the operation in which the first heating coil 6 and the second heating coil 7 are connected in parallel.
the device in the case of a load associated with a large number of the connected heating coil elements and making the impedance smaller, for example, in the case of the second load 14b (the eight heating coil elements), the device is operated in the alternate heating mode with the number of the connected heating coil elements reduced by 1/2.
the impedance of the heating coils connected to the semiconductor switches is doubled.
the current to the heating coils can consequently be suppressed and the input power can be lowered.
a plurality of resonance circuits made up of heating coil elements inductively heating a load and resonance capacitors are connected to three serially-connected semiconductor switches and, in the case of a load associated with a small number of connections of the heating coil elements and making the impedance larger, the device is operated in the simultaneous heating mode in which the first and third semiconductor switches 10, 12 are alternately made conductive while the second semiconductor switch 11 is made always conductive so as to supply power to the first heating coil and the second heating coil at the same time.
the device is operated in the alternate heating mode by alternately repeating the operations at short constant intervals between the first single heating mode in which the second and third semiconductor switches 11, 12 are alternately made conductive while the first semiconductor switch 10 is made always conductive so as to supply high-frequency power to the second heating coil 7, and the second single heating mode in which the first and second semiconductor switches 10, 11 are alternately made conductive while the third semiconductor switch 12 is made always conductive so as to supply high-frequency power to the first heating coil 6.
the power is supplied to the first heating coil 6 and the second heating coil 7 in this way, a predetermined input power can be applied at a constant operation frequency to a load even when the number of the heating coil elements used is changed, and the induction heating device generating no interference sound and excellent in controllability can be achieved.
the configuration of the induction heating device of the seventh embodiment has the same configuration as the induction heating device of the sixth embodiment depicted in Fig. 27 and is different in a method of controlling the heating operation for the heating coils.
the induction heating device of the seventh embodiment has a mode of heating a plurality of heating coils in the simultaneous heating mode and this simultaneous heating mode is the same operation as the simultaneous heating mode described with reference to Fig. 31 in the sixth embodiment described above.
the induction heating device of the seventh embodiment has the step-down simultaneous heating mode in addition to the simultaneous heating mode.
Fig. 35 is a waveform diagram of an operation state of the step-down simultaneous heating mode in the seventh embodiment.
Fig. 35 includes (a) to (c) as gate voltage waveforms of the first to third semiconductor switches 10, 11, and 12, (d) as a current waveform of the first heating coil 6, and (e) as a current waveform of the second heating coil 7.
the control part 13 controls the conductive state/non-conductive state (on-state/off-state) of the first semiconductor switch (Q1a) 10, the second semiconductor switch (Q1b) 11, and the third semiconductor switch (Q1c) 12.
the control part 13 puts the first semiconductor switch (Q1a) 10 into the non-conductive state (off-state), the second semiconductor switch (Q1b) 11 into the conductive state (on-state), and the third semiconductor switch (Q1c) 12 into the non-conductive state (off-state), the power is supplied to the first heating coil 6 and the second heating coil 7 that are the heating coil groups at the same time through the path from the smoothing capacitor 5 ⁇ the first opening/closing part 20 (the corresponding first opening/closing part elements) ⁇ the first resonance capacitor 8 (the corresponding first resonance capacitor elements) ⁇ the first heating coil 6 (the corresponding first heating coil elements) ⁇ the second semiconductor switch (Q1b) 11 ⁇ the second heating coil 7 (the corresponding second heating coil elements) ⁇ the second resonance capacitor 9 (the corresponding second resonance capacitor elements) ⁇ the second opening/closing part 21 (the corresponding second opening/closing part elements).
the series circuit of the first heating coil 6 and the first resonance capacitor 8 and the series circuit of the second heating coil 7 and the second resonance capacitor 9 are connected to the smoothing capacitor 5 in series. Therefore, a divided voltage is applied to each of the series circuits and, particularly when each of the series circuits has substantially the same circuit constant, an approximately 1/2 voltage is applied.
the control part 13 puts the second semiconductor switch (Q1b) 11 into the non-conductive state at the conduction time when the current value detected by the input current detecting part 3 indicates the predetermined current value (termination of the section B). After the predetermined transition time (section Y) has elapsed from the termination of the section B, the control part 13 puts the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12 into the conductive state (section A).
the control part 13 puts the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12 into the non-conductive state at the conduction time when the current value detected by the input current detecting part 3 indicates the predetermined current value. After the predetermined transition time (section X) has elapsed from the termination of the section A, the control part 13 puts the second semiconductor switch (Q1b) 11 into the conductive state again.
the control part 13 can put the second semiconductor switch (Q1b) 11 and a set of the first semiconductor switch (Q1a) 10 and the third semiconductor switch (Q1c) 12 alternately into the conductive state/non-conductive state, thereby supplying a high-frequency current of about 20 kHz to 60 kHz to both the first heating coil 6 and the second heating coil 7 that are the heating coil elements at the same time.
a desired high-frequency magnetic field generated from the heating coils supplied with the high-frequency current is supplied to the load such as a pot.
control part 13 can determine the presence/absence of the load and/or the type of the load by detecting a resonance voltage generated at predetermined operation frequency and conduction time.
the operation frequency is kept constant for preventing the inference sound with an adjacent load in the configuration of the seventh embodiment, a large difference may be generated in the input power generated during the conduction time depending on the number of the connected heating coil elements supplied with the high-frequency power as depicted in Fig. 36 . Therefore, the input power cannot sufficiently be lowered for some shapes (sizes) of loads and the heating device may have poor usability because of an increased control width of power control etc.
the device in the case of a load having a small load shape and associated with a small number of the connected heating coil elements, for example, if the number of the connected heating coil elements is four (if two heating coil elements are connected in each of the first heating coil 6 and the second heating coil 7), the device is operated in the simultaneous heating mode that is the operation in which the first heating coil 6 and the second heating coil 7 are connected in parallel.
the operation in the simultaneous heating mode makes the impedance of the load too small, resulting in a situation in which a current easily flows through the connected heating coil elements and a situation in which the input current is excessively supplied during the conduction time.
the input power is set to an upper line.
the device is operated in the step-down simultaneous heating mode. Since the step-down simultaneous heating mode reduces the input voltage applied to the first heating coil and the second heating coil that are the heating coil groups, the step-down simultaneous heating mode can create a situation in which the input current hardly flows even if the impedance is reduced. For example, the first heating coil 6 and the second heating coil have the same number of the heating coil elements, the input voltage is reduced by half. In Fig. 36 , as indicated by a characteristic example when ten heating coil elements are operated in the step-down simultaneous heating mode, the input power is set to a lower line.
the power becomes 1/4 under the same operation conditions (the operation frequency and the conduction time).
the configuration of the seventh embodiment may be the configuration having the alternate heating mode described with reference to Figs. 32A and 32B in the sixth embodiment in addition to the simultaneous heating mode and the step-down simultaneous heating mode.
the input power for the conduction time becomes smaller in the order of the simultaneous heating mode, the alternate heating mode, and the step-down simultaneous heating mode under the same conditions depending on the impedance in the load. Therefore, the configuration of the seventh embodiment also enables a method in which the heating modes are sequentially switched depending on a condition such as the number of connections of the heating coil elements.
a plurality of resonance circuits made up of heating coil elements inductively heating a load and resonance capacitors are connected to three serially-connected semiconductor switches and, in the case of a load associated with a small number of connections of the heating coil elements and making the impedance larger, the device is operated in the simultaneous heating mode in which the first and third semiconductor switches 10, 12 are alternately made conductive while the second semiconductor switch 11 is made always conductive so as to supply power to the first heating coil 6 and the second heating coil 7 at the same time.
the device in the case of a load associated with a large number of connections of the heating coil elements and making the impedance smaller, the device is operated in the step-down simultaneous heating mode in which the second semiconductor switch and a set of the first semiconductor switch and the third semiconductor switch are alternately made conductive to supply the high-frequency power to the first heating coil 6 and the second heating coil 7 at the same time to reduce the voltage applied to the heating coils. Since the power is supplied to the first heating coil 6 and the second heating coil 7 in this way, a predetermined input power can be applied at a constant operation frequency to a load even when the number of the heating coil elements used is changed, and the induction heating device generating no interference sound and excellent in controllability can be achieved.
Fig. 37 is a plane view of heating coil groups having pluralities of heating coil elements disposed direct under the top plate 15 in the configuration of the induction heating device of the eighth embodiment according to this disclosure.
the induction heating device of the eighth embodiment is different from the sixth embodiment and the seventh embodiment described above in that the heating coil elements making up the first heating coil 6 defined as the heating coil group are alternately arranged with the heating coil elements making up the second heating coil 7 defined as the heating coil group on the same plane.
the first heating coil 6 is made up of 12 heating coil elements 6a to 61 and the second heating coil 7 is made up of 12 heating coil elements 7a to 71.
the 24 heating coil elements 6a to 61, 7a to 71 are arranged in 4 rows ⁇ 6 columns in zigzags. In rows and columns adjacent to the rows and columns in which the heating coil elements 6a to 61 of the first heating coil 6 are arranged, the heating coil elements 7a to 71 of the second heating coil 7 are respectively arranged.
the control part 13 can symmetrically operate the semiconductor switches in each of the heating modes and therefore can provide reliable and simple control and can create favorable heating distribution for the load.
the configuration of the induction heating device of the eighth embodiment since the heating coil elements are alternately arranged to reduce a difference between the number of connections of the heating coil elements forming the first heating coil 6 and the number of connections of the heating coil elements forming the second heating coil 7 in all the heating modes, the power can uniformly be supplied from the heating coil elements to the load. Therefore, the configuration of the induction heating device of the eighth embodiment can achieve a heating device capable of forming favorable heating distribution for the load.
the induction heating device of this disclosure is configured such that the control part controls the first semiconductor switch, the second semiconductor switch, and the third semiconductor switch depending on a state of a load when the load is placed on the heating region, for example, a material, a size, etc., of the load, so as to select and perform an appropriate heating mode.
the heating modes performed in the induction heating device of this disclosure include the simultaneous heating mode in which the high-frequency power is supplied to the first heating coil and the second heating coil at the same time, the first single heating mode in which the high-frequency power is supplied to the second heating coil, the second single heating mode in which the high-frequency power is supplied to the first heating coil, the alternate heating mode in which the first single heating mode and the second single heating mode are alternately performed, and the step-down simultaneous heating mode in which the high-frequency power can be supplied to the first heating coil and the second heating coil in a step-down state at the same time.
the induction heating device of this disclosure is configured to select an appropriate heating mode for a detected load out of these heating modes so as to inductively heat the load.
the induction heating device of this disclosure may be configured such that when the heating mode selected for the detected load is performed and an inconvenient state occurs such as an excessively high input power etc., the heating mode is sequentially switched to those suppressing the input power.
One embodiment of the induction heating device of the present disclosure includes a series connection body of a first semiconductor switch, a second semiconductor switch, and a third semiconductor switch connected to a power source; a series connection body of a first resonance capacitor and a first heating coil connected in parallel to the first semiconductor switch and magnetically coupled to a load; a series connection body of a second resonance capacitor and a second heating coil connected in parallel to the third semiconductor switch and magnetically coupled to a load; and a control part controlling the first to third semiconductor switches.
the control part includes the first single heating mode of performing an operation in which the second and third semiconductor switches are alternately made conductive while the first semiconductor switch is made always conductive so as to supply the high-frequency power to the second heating coil and the second single heating mode of performing an operation in which the first and second semiconductor switches are alternately made conductive while the third semiconductor switch is made always conductive so as to supply the high-frequency power to the first heating coil.
the first to third semiconductor switches respectively include a first diode, a second diode, and a third diode connected in reversely parallel to the respective semiconductor switches.
the control part configured as described above can perform the alternate heating mode in which the first single heating mode and the second single heating mode are repeated in a short cycle when supplying a power from both the first heating coil and the second heating coil to a load, thereby supplying an average high-frequency power uniformly to both the first heating coil and the second heating coil at the same time.
the inexpensive induction heating device can be provided that generates no interference sound, that is excellent in cooking performance, and that even has a reduced number of components and a smaller circuit mounting area.
Another embodiment of the induction heating device of the present disclosure includes a series connection body of first to third semiconductor switches connected to a smoothing capacitor operating as an AC power source; a series connection body of a first resonance capacitor and a first heating coil connected in parallel to the first semiconductor switch and having at least one heating coil element magnetically coupled to a load; a series connection body of a second resonance capacitor and a second heating coil connected in parallel to the third semiconductor switch and having at least one heating coil element magnetically coupled to a load; and a control part controlling the first to third semiconductor switches.
the control part includes the simultaneous heating mode in which the first and third semiconductor switches are alternately made conductive while the second semiconductor switch is conductive so as to supply the high-frequency power to the first heating coil and the second heating coil.
the control part also includes an alternate operation mode of alternately repeating a first operation (the first single heating mode) in which the second semiconductor switch and the third semiconductor switch are alternately made conductive while the first semiconductor switch is conductive so as to supply the high-frequency power to the second heating coil and a second operation (the second single heating mode) in which the first semiconductor switch and the second semiconductor switch are alternately made conductive while the third semiconductor switch is conductive so as to supply the high-frequency power to the first heating coil.
the control part including the simultaneous heating mode and the alternate heating mode in this way controls the first to third semiconductor switches such that the heating modes are switched depending on a material of a load.
the induction heating device using a plurality of heating coils to heat the same load is configured such that the simultaneous heating mode is performed in the case of a material making the impedance larger in the load coupled to the heating coils while the alternate heating mode is performed in the case of a material making the impedance smaller in the load so as to bring the impedances close to each other even when the materials are different. Therefore, the necessary input power can be applied to a load at a constant frequency even if the material of the load is changed, and the induction heating device generating no interference sound and excellent in controllability can be provided.
a further embodiment of the induction heating device of the present disclosure includes a series connection body of first to third semiconductor switches connected to a smoothing capacitor operating as an AC power source; a plurality of first heating coil elements arranged in a matrix shape and connected in parallel to the first semiconductor switch; a plurality of second heating coil elements connected in parallel to the third semiconductor switch; a plurality of first resonance capacitor elements connected in series respectively to the plurality of the first heating coil elements; a plurality of second resonance capacitor elements connected in series respectively to the plurality of the second heating coil elements; and a load detecting part detecting the presence of a heatable load in the vicinity of each of the pluralities of the first and second heating coil elements.
the induction heating device of the further embodiment includes an opening/closing part having a plurality of first opening/closing part elements interrupting the supply of the high-frequency power to each of the plurality of the first heating coil elements (a first heating coil) and a plurality of second opening/closing part elements interrupting the supply of the high-frequency power to each of the plurality of the second heating coil elements (a second heating coil).
the induction heating device of the further embodiment configured in this way is configured such that if the same load is heated, the control is provided to supply the high-frequency power by using the first and second opening/closing part elements to the heating coil elements having a load detected in the vicinity thereof by the load detecting part so as to select the appropriate heating mode and control the operation of the first to third semiconductor switches depending on the number of connections of the heating coil elements supplied with the high-frequency power.
the induction heating device of the further embodiment configured as described above can switch the operations of the first to third semiconductor switches depending on the number of connections of the heating coil elements in the first heating coil and the second heating coil made up of heating coil groups, thereby changing the respective impedances and applied voltages of the first heating coil and the second heating coil. Therefore, the induction heating device of the further embodiment can adjust power even when the operation frequency is kept constant.
the inexpensive induction heating device can be provided that generates no interference sound even when the high-frequency power is supplied to a plurality of the heating coil elements, that is excellent in cooking performance, and that even has a reduced number of components and a smaller circuit mounting area.
the induction heating device of the present disclosure is described by taking as an example an inductive heating cooker inductively heating a load such as a pot for heating and cooking foodstuffs, the induction heating device is applicable to a normal induction heating device as well as a power feeding device to non-contact power feeding equipment including a power-receiving coil other than the inductive heating cooker.
An induction heating device generates no interference sound even when high-frequency power is applied to a plurality of heating coil elements, has excellent cooking performance, even has a reduced number of components and a smaller circuit mounting area, can inexpensively be achieved, and therefore is useful in various uses of induction heating equipment.

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Physics & Mathematics (AREA)
Electromagnetism (AREA)
Induction Heating Cooking Devices (AREA)
General Induction Heating (AREA)

EP13848712.9A 2012-10-24 2013-10-23 Induktionsheizvorrichtung Active EP2914059B1 (de)

Applications Claiming Priority (5)

Application Number	Priority Date	Filing Date	Title
JP2012234387		2012-10-24
JP2012234386		2012-10-24
JP2013111631		2013-05-28
JP2013111632		2013-05-28
PCT/JP2013/006265 WO2014064932A1 (ja)	2012-10-24	2013-10-23	誘導加熱装置

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EP2914059A1 true EP2914059A1 (de)	2015-09-02
EP2914059A4 EP2914059A4 (de)	2015-11-04
EP2914059B1 EP2914059B1 (de)	2017-12-06

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JP (1)	JPWO2014064932A1 (de)
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Also Published As

Publication number	Publication date
EP2914059B1 (de)	2017-12-06
EP2914059A4 (de)	2015-11-04
JPWO2014064932A1 (ja)	2016-09-08
WO2014064932A1 (ja)	2014-05-01
CN104604328B (zh)	2016-07-06
CN104604328A (zh)	2015-05-06

Publication	Publication Date	Title
EP2914059B1 (de)	2017-12-06	Induktionsheizvorrichtung
US9326329B2 (en)	2016-04-26	Induction heating apparatus
US9060389B2 (en)	2015-06-16	Induction heating cooker
JP5662344B2 (ja)	2015-01-28	誘導加熱装置およびそれを備えた誘導加熱調理器
CN103931272B (zh)	2016-01-06	感应加热装置
US11324079B2 (en)	2022-05-03	Induction heating cooker
US12028954B2 (en)	2024-07-02	Induction heating apparatus and method for controlling same
US20220248505A1 (en)	2022-08-04	Method for controlling the provision of electric power to an induction coil
JP2003257604A (ja)	2003-09-12	インバータ調理器
US11805576B2 (en)	2023-10-31	Domestic appliance
EP3562267B1 (de)	2020-09-23	Steuerschaltungen und verfahren für verteilte induktionsheizvorrichtungen
EP3562268B1 (de)	2020-10-21	System und verfahren zur steuerung von induktionserwärmungsvorrichtungen mit in reihe verbundenen schaltvorrichtungen
EP3758442B1 (de)	2024-01-24	Induktionserwärmungskocher
US20210360750A1 (en)	2021-11-18	System and method for controlling quasi-resonant induction heating devices
US20190261466A1 (en)	2019-08-22	Domestic appliance
US11153940B2 (en)	2021-10-19	Domestic appliance device
JP4100333B2 (ja)	2008-06-11	炊飯器
US20230309201A1 (en)	2023-09-28	Cooktop device
CN103891400A (zh)	2014-06-25	感应加热装置
US20160374156A1 (en)	2016-12-22	Induction heat cooking apparatus
JP2011150799A (ja)	2011-08-04	誘導加熱装置
KR101757976B1 (ko)	2017-07-26	전자 유도 가열 조리기 및 이의 구동 방법
JP2012245301A (ja)	2012-12-13	炊飯器
KR20160040079A (ko)	2016-04-12	전자 유도 가열 조리기 및 이의 구동 방법

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EP2914059A1 - Induktionsheizvorrichtung - Google Patents

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