JPH10106738A - Induction heater apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accomplish cost reduction more than before by decreasing a breakdown voltage of a switching element used in an inverter circuit for an induction heater apparatus. SOLUTION: This apparatus comprises a first switching element 14 connected in series with a coil 12 through a direct current voltage source 11, a first capacitor 13 combined with the coil 12 to constitute a resonance circuit, a series connection between a second resonance capacitor 16 and a second switching element 17 connected in parallel with the coil 12, and a control circuit 19 for conductively controlling the first switching element 14 and the second switching element 17. At the time of conductively controlling the switching elements 14 and 17 alternately, the conduction time of the first switching element 14 is fixed, and that of the second switching element 17 is changed. Then the second resonance element 16 and the second switching element 17 are caused to clamp the voltage of the first switching element 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating apparatus typified by an induction heating cooker used in ordinary households and restaurants, and more particularly, to an input power control means of an induction heating inverter circuit. The present invention relates to an induction heating device having the following characteristics.

[0002]

2. Description of the Related Art In recent years, induction heating cookers as a safe heating source have been in the spotlight. In this induction heating cooker, a switching element is turned on and off, and a high-frequency current is applied to the coil to generate an induction magnetic field near the coil. This is a device that utilizes the heat generated by iron loss by generating an induced current due to an induced magnetic field.

An example of an inverter circuit of an induction heating cooker using control means in a conventional induction heating cooker will be described with reference to FIGS. 54 and 55.

FIG. 54 shows an example of a circuit of a conventional induction heating cooker. In FIG. 54, reference numeral 551 denotes a DC power supply, and 552 denotes a heating coil, on which an object to be heated (a pan or the like) is placed, though not particularly shown in the figure. Reference numeral 553 denotes a first capacitor, which forms a resonance circuit with the heating coil 552. Reference numeral 554 denotes a first switching element, which uses a high-breakdown-voltage IGBT in this example. Reference numeral 555 denotes a reverse conducting diode, which forms a parallel circuit with the first switching element 554. 557 is a control circuit for controlling the first switching element 555, 558 is a voltage detection means for the first switching element, detects the voltage Vce across the first switching element 554, and
59. The control circuit 557 detects Vce by the voltage detection means 558 of the first switching element, and controls the first switching element 554 to conduct when the voltage across the first switching element 554 becomes zero volt or less. I have.

FIG. 55 shows operation waveforms of the conventional inverter circuit. FIG. 55A shows a drive signal output from the control circuit 559, and when this output is High, the first switching element 554 becomes conductive. (B) is a current Ic flowing through the IGBT of the first switching element 554 and the reverse conducting diode 555, and (C) is a current Ic flowing through the first switching element 554.
Is the voltage Vce between both ends.

The operation of this circuit will be described below with reference to FIGS. 54 and 55. After conducting the first switching element 554 for a predetermined time, the control circuit 559 opens to resonate the resonance circuit including the heating coil 552 and the first capacitor 553. Further, the control circuit 557 detects the voltage Vce across the first switching element by the voltage detecting means 558 of the first switching element, and when Vce becomes lower than zero volt, the first switching element 55 again.
4 is turned on. In order to repeat the above operation, in response to the drive signal (A) output from the control circuit 559 in FIG.
As shown in (C), an object to be heated such as a pan placed on the heating coil 552 generates heat. The power supplied to the object to be heated and the voltage Vce of the first switching element can be freely controlled by controlling the conduction time of the switching element 554.

[0007]

However, in the above-described conventional inverter circuit control means, since Vce which is a resonance voltage increases with an increase in input power, a device requiring a large input power requires a peak of Vce. Since the value becomes high, a switching element with a high withstand voltage is required, which hinders cost reduction. When a predetermined input power is applied, the operating frequency is determined by the resonance between the coil and the first capacitor. Therefore, if the frequency matches the natural vibration frequency of the object to be heated, such as a pan, it is annoying. Sound was generated.

[0008]

According to the present invention, there is provided a coil having one end connected to a DC power supply, and a first switching element connected in series with the coil to the DC power supply. A first capacitor forming a resonance circuit with the coil, a series connection of a second switching element and a second resonance capacitor connected in parallel with the coil, and conduction control of the first switching element and the second switching element. A control circuit for controlling the conduction of the switching elements alternately, fixing the conduction time of the first switching element to control the input power, and changing the conduction time of the second switching element. It is.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 is a coil having one end connected to a DC power supply, a first switching element connected in series with the coil with respect to the DC power supply, and a first reverse connection. A parallel circuit of a conducting diode, a first capacitor forming a resonant circuit with the coil, a second resonant capacitor connected in series with a parallel circuit of a second switching element and a second reverse conducting diode connected in parallel with the coil, And a control circuit for controlling conduction of the first switching element and the second switching element,
The control circuit controls the conduction of each of the switching elements alternately, fixes the conduction time of the first switching element to control the input power, and changes the conduction time of the second switching element by changing the first switching element. Although the voltage between both ends increases with an increase in the input power, the resonance voltage of the first switching element is clamped by the second resonance capacitor, the second switching element, and the second reverse conducting diode, and the voltage is controlled at a lower end voltage than before. It is possible to do.

According to a second aspect of the present invention, in order to control the input power, the conduction time of the first switching element is changed, and in order to fix the conduction time of the second switching element, the voltage across the first switching element is reduced. Although it increases with an increase in input power, it is possible to control the resonance voltage of the first switching element in a state where the resonance voltage of the first switching element is clamped for a fixed time by the second resonance capacitor, the second switching element, and the second reverse conducting diode. Further, as compared with the first aspect of the present invention, the operating frequency is reduced when the input power is large, so that the switching loss of the first switching element can be reduced.

According to a third aspect of the present invention, there is provided the circuit according to the first aspect, further comprising current detection means for detecting an output current of the DC power supply, and controlling input power based on information from the current detection means. , Or both means, so that the input power can be controlled more accurately than the inventions of claim 1 and claim 2.

According to a fourth aspect of the present invention, in the circuit of the first aspect, there is provided an operating frequency detecting means for detecting an operating frequency of a component such as a coil, and an input power of the input power is determined based on information from the operating frequency detecting means. Since the control is performed by using the means of claim 1, claim 2, or both, the input power can be controlled more accurately than the inventions of claim 1 and claim 2.

According to a fifth aspect of the present invention, in the circuit according to the first aspect, there is provided an operating frequency detecting means for detecting an operating frequency of a component such as a coil, wherein the operating frequency is set in advance by information from the operating frequency detecting means. The input power is controlled within the predetermined operating frequency range by using the means of claim 1, claim 2, or both of them, so that the input power can be controlled without generating harsh sounds from loads and circuit components. Can control.

According to a sixth aspect of the present invention, in the circuit of the first aspect, there is provided a peak current value detecting means for detecting a peak value of a current flowing through the first switching element, the first reverse conducting diode, or both. Since the input power is controlled by the information from the peak current value detecting means using the first, second, or both means, the present invention can provide a control device that is capable of controlling the input power as compared with the first and second aspects. The input power can be controlled with high accuracy.

According to a seventh aspect of the present invention, in the circuit of the first aspect, there is provided an effective value current detecting means for detecting an effective value of a current flowing through the first switching element, the first reverse conducting diode, or both. In order to control the input power using the information from the effective value current detecting means, using the means of claim 1, claim 2, or both means,
As compared with the first and second aspects of the present invention, the input power can be controlled with higher accuracy.

According to an eighth aspect of the present invention, in the circuit of the first aspect, there is provided a peak current value detecting means for detecting a peak value of a current flowing through the second switching element, the second reverse conducting diode, or both. Since the input power is controlled by the information from the peak current value detecting means using the first, second, or both means, the present invention can provide a control device that is capable of controlling the input power as compared with the first and second aspects. The input power can be controlled with high accuracy.

According to a ninth aspect of the present invention, in the circuit of the first aspect, there is provided an effective value current detecting means for detecting an effective value of a current flowing through the second switching element, the second reverse conducting diode, or both. In order to control the input power using the information from the effective value current detecting means, using the means of claim 1, claim 2, or both means,
As compared with the first and second aspects of the present invention, the input power can be controlled with higher accuracy.

According to a tenth aspect of the present invention, the circuit according to the first aspect further comprises an effective value current detecting means for detecting an effective value of a current flowing through the second switching element and the second reverse conducting diode, The input power is controlled such that the effective value current flowing through the second switching element and the second reverse conducting diode, that is, the effective value current flowing through the second capacitor, is equal to or less than a predetermined value, based on information from the current detection means. Since this is performed using the first, second, or both means, the heat generation of the second capacitor can be suppressed and breakage can be prevented.

According to an eleventh aspect of the present invention, in the circuit according to the first aspect, there is provided a peak current value detecting means for detecting a peak value of a current flowing through the coil, and the input power is determined based on information from the peak current value detecting means. The control of claim 1,
Since the control is performed using the means of claim 2 or both of them, the input power can be controlled more accurately than the inventions of claim 1 and claim 2.

According to a twelfth aspect of the present invention, in the circuit of the first aspect, there is provided an effective value current detecting means for detecting an effective value of a current flowing through the coil, and the input power is determined based on information from the effective value current detecting means. Is performed using the means of claim 1, claim 2, or both means, so that the input power can be controlled more accurately than the inventions of claim 1 and claim 2.

According to a thirteenth aspect of the present invention, in the circuit according to the first aspect, there is provided a peak current value detecting means for detecting a peak value of a current flowing through the first capacitor, and the information is supplied from the peak current value detecting means. Since the control of the input power is performed by using the means of claim 1 or claim 2 or both, the control of the input power can be performed more accurately than the inventions of claim 1 and claim 2.

According to a fourteenth aspect of the present invention, in the circuit of the first aspect, an effective value current detecting means for detecting an effective value of a current flowing through the first capacitor is provided, and the information from the effective value current detecting means is provided. Since the control of the input power is performed by using the means of claim 1 or claim 2 or both, the control of the input power can be performed more accurately than the inventions of claim 1 and claim 2.

According to a fifteenth aspect of the present invention, in the circuit according to the first aspect, a voltage detecting means is provided between both ends of the first switching element, and the input power is controlled based on information from the voltage detecting means. Since the control is performed using the means of claim 2, the input power can be controlled with higher accuracy than the inventions of claim 1 and claim 2.

According to a sixteenth aspect of the present invention, in the circuit of the first aspect, a voltage detecting means is provided between both ends of the second switching element, and the input power is controlled based on information from the voltage detecting means. Since the control is performed using the means of claim 2, the input power can be controlled with higher accuracy than the inventions of claim 1 and claim 2.

According to a seventeenth aspect of the present invention, in the circuit according to the first aspect, the voltage is detected by the voltage detecting means at both ends of the first switching element, the voltage detecting means at both ends of the second switching element, and each of the voltage detecting means at both ends. There is provided a subtraction means for obtaining a voltage difference, and the input power is controlled by means of the first and second means according to information from the subtraction means. As a result, the input power can be accurately controlled.

According to an eighteenth aspect of the present invention, in the circuit according to the first aspect, a voltage detecting means is provided between both ends of the first capacitor, and the input power is controlled by information from the voltage detecting means between both ends. Since the control is performed using the means of the second aspect, the input power can be controlled with higher accuracy than the inventions of the first and second aspects.

According to a nineteenth aspect of the present invention, in the circuit of the first aspect, a voltage detecting means is provided between both ends of the second capacitor, and the input power is controlled based on information from the voltage detecting means. Since the control is performed using the means of the second aspect, the input power can be controlled with higher accuracy than the inventions of the first and second aspects.

According to a twentieth aspect of the present invention, in the circuit according to the third aspect, there is provided means for detecting a voltage between both ends of the first switching element, and the control circuit according to the third aspect controls the input power and the first switching. Since it has a function of controlling the voltage between both ends of the element to be equal to or less than a predetermined value, it is possible to control the input current while protecting the first switching element.

According to a twenty-first aspect of the present invention, in the circuit according to the third aspect, there is provided a means for detecting a voltage between both ends of the second switching element, and the control circuit according to the third aspect controls the input power and the second switching. Since it has a function of controlling the voltage across the element to be equal to or lower than a predetermined value, it is possible to control the input current while protecting the second switching element.

According to a twenty-second aspect of the present invention, in the circuit according to the third aspect, a means for detecting a voltage between both ends of the first capacitor is provided.
Since it has a function of controlling the voltage across the first capacitor to be equal to or lower than a predetermined value, it is possible to control the input current while protecting the first capacitor.

According to a twenty-third aspect of the present invention, in the circuit according to the third aspect, there is provided means for detecting a voltage between both ends of the second capacitor, wherein the control circuit according to the third aspect controls input power,
Since it has a function of controlling the voltage across the second capacitor to a predetermined value or less, it is possible to control the input current while protecting the second capacitor.

[0032]

【Example】

(Embodiment 1) FIG. 1 shows an example of a circuit of an induction heating cooker according to a first embodiment of the present invention. In FIG. 1, reference numeral 11 denotes a DC power supply. Reference numeral 12 denotes a heating coil, one end of which is connected to the positive side of the DC power supply 1, on which an object to be heated (a pan or the like) is placed, although not particularly shown in the figure. A first capacitor 13 forms a parallel resonance circuit with the heating coil 12. 1
Reference numeral 4 denotes a first switching element, which uses an IGBT in this example, and 15 denotes a first reverse conducting diode which forms a parallel circuit with the first switching element 14. The parallel circuit of the first switching element 14 and the first reverse conducting diode 15 is connected to the other end of the heating coil 12 and the minus side of the DC power supply 11. The configuration of the DC power supply 11, the heating coil 12, the first capacitor 13, the first switching element 14, and the first reverse conducting diode 15 is the same as that of the circuit shown in the conventional example. Are connected in series with the parallel circuit of the second switching element and the second reverse conducting diode of 18 to form a parallel circuit with the heating coil 12, and the series circuit of the second capacitor and the second switching element 16 It has a role of clamping the resonance voltage when the switching element 15 is released by charging and discharging the second capacitor. The control circuit 19 outputs a drive signal for alternately turning on the first switching element 14 and the second switching element 17, and performs input power control.

FIG. 2 shows voltage-current waveforms of the first switching element and the second switching element shown in the circuit diagram of FIG. FIG. 2 shows that vge1 is the gate-emitter voltage of the first switching element, vge2 is the gate-emitter voltage of the second switching element, ic1 and vce1 are the collector current and the collector-emitter voltage of the first switching element, and ic2 and vce2 represents the collector current and the collector-emitter voltage of the second switching element, respectively, and shows how the voltage when the first switching element is released is clamped when the second switching element is conductive.

FIG. 3 shows an example of the input power characteristic by the control means of this embodiment. FIG. 3 shows the characteristics with the horizontal axis representing the conduction time of the second switching element and the vertical axis representing the input power. The input power decreases as the conduction time of the second switching element increases. Can be performed during the conduction time of the second switching element.

In the above description, the second capacitor 1
6 and the series circuit of the second switching element 17 and the second reverse conducting diode 18 is configured as shown in FIG. 1, but as shown in FIG. The present invention can be similarly implemented by a configuration in which 18 is replaced, or a configuration in which a series circuit is connected in parallel to the first switching element 14 as shown in FIG.

FIG. 6 shows an example of an input power characteristic by another control means of this embodiment. FIG. 6 shows the characteristics with the horizontal axis representing the conduction time of the first switching element and the vertical axis representing the input power. Since the input power increases as the conduction time of the first switching element increases, the control of the input power is performed. Can be performed during the conduction time of the first switching element. Also, since the operating frequency decreases when the input power is large,
It is possible to reduce the switching loss of the first switching element.

(Embodiment 2) FIG. 7 shows an example of a circuit diagram of an induction heating cooker according to a second embodiment of the present invention. In this configuration, current detection means 20 for detecting an output current from the DC power supply 11 is added to the circuit configuration of the first embodiment, and feedback is performed based on output current information to control input power.

FIG. 8 shows the DC power supply 1 shown in the circuit diagram of FIG.
1 shows an example of the characteristics of output current and input power from No. 1. FIG.
Represents the characteristics with the horizontal axis representing the output current from the DC power supply 11 and the vertical axis representing the input power. Since the input power increases as the output current from the DC power supply 11 increases, the control of the input power is as follows. By performing feedback based on information on the output current of the DC power supply, highly accurate control can be performed.

(Embodiment 3) FIG. 9 shows an example of a circuit diagram of an induction heating cooker according to a third embodiment of the present invention. In this configuration, the circuit configuration of the first embodiment is provided with frequency detecting means 21 for detecting the operating frequency of the heating coil 12, and the input power is controlled by performing feedback based on information on the operating frequency.

FIG. 10 shows the characteristics of the operating frequency and the input power detected by the operating frequency detecting means 21 shown in the circuit diagram of FIG. 9 when the input power is controlled using the control means of the first embodiment. An example is shown below. FIG. 10 shows the characteristics with the horizontal axis representing the operating frequency and the vertical axis representing the input power, showing that the conduction time of the second switching element decreases, that is, the input power increases as the operating frequency increases. .
Therefore, the input power can be controlled with high accuracy by performing feedback based on the information on the operating frequency.

FIG. 11 shows the characteristics of the operating frequency and the input power detected by the operating frequency detecting means 21 shown in the circuit diagram of FIG. 9 when the input power is controlled using the control means of this embodiment. An example is shown below. FIG. 11 illustrates the characteristics with the horizontal axis representing the operating frequency and the vertical axis representing the input power, and shows that the input power increases as the conduction time of the first switching element increases, that is, as the operating frequency decreases. .
Therefore, the input power can be controlled with high accuracy by performing feedback based on the information on the operating frequency.

FIG. 12 shows the characteristics of the operating frequency and the input power detected by the operating frequency detecting means 21 shown in the circuit diagram of FIG. 9 when the input power is controlled using another control means of this embodiment. An example is shown below. As described with reference to FIGS. 10 and 11, the reduction in the conduction time of the second switching element is as follows.
There is a characteristic that increases the operating frequency and the input power,
The increase in the conduction time of the first switching element has a function of reducing the operating frequency and increasing the input power. This characteristic is applied within a predetermined operating frequency range, and the input power is increased as shown by the arrow in the figure. With this control method, it is possible to perform control while avoiding the natural vibration frequency of a load such as a pan.

Also, in this embodiment, the operating frequency is detected from the current of the heating coil. However, since the operating frequencies of all the components constituting the inverter are the same, for example, the operating frequency of the switching element is changed. The values obtained are the same even if the configuration for detection is used.

(Embodiment 4) FIG. 13 shows an example of a circuit diagram of an induction heating cooker according to a fourth embodiment of the present invention. This configuration is different from the circuit configuration of the first embodiment in that the peak current value detection unit 2 detects the peak value of the current flowing through the first switching element.
2, which controls the input power by performing feedback based on the information on the peak current value.

FIG. 14 shows an example in which the control means of this embodiment is used.
FIG. 14 shows characteristics of a peak current value and input power detected by peak current value detection means described in the circuit diagram of FIG. FIG.
Represents the characteristics with the horizontal axis representing the peak current value and the vertical axis representing the input power, the increase in the conduction time of the first switching element,
That is, since the input power increases with an increase in the peak current value, the input power can be controlled with high accuracy by performing feedback based on the information on the peak current value.

(Embodiment 5) FIG. 15 shows an example of a circuit diagram of an induction heating cooker according to a sixth embodiment of the present invention. This configuration is different from the circuit configuration of the first embodiment in that the peak current value detection unit 2 detects the peak value of the current flowing through the first reverse conducting diode.
2, which controls the input power by performing feedback based on the information on the peak current value.

FIG. 16 shows an example in which the control means of this embodiment is used.
FIG. 16 shows characteristics of a peak current value and input power detected by peak current value detection means described in the circuit diagram of FIG. FIG.
Represents the characteristics with the horizontal axis representing the peak current value and the vertical axis representing the input power.By increasing the conduction time of the first switching element, the peak current value of the first reverse conduction diode becomes the peak current value of the first switching element. Since the input power increases in the same manner as the value, the input power also increases. Therefore, the input power can be controlled with high accuracy by performing feedback based on the information on the peak current value. In both FIGS. 14 and 16, the peak current value increases as the conduction time of the first switching element increases, so that even if the sum is obtained, the increase characteristic is obtained.

(Embodiment 6) FIG. 17 shows an example of a circuit diagram of an induction heating cooker according to a sixth embodiment of the present invention. In this configuration, an effective value current detecting means 23 for detecting an effective value of a current flowing through the first switching element is added to the circuit configuration of the first embodiment. Control.

FIG. 18 shows an example in which the control means of this embodiment is used.
18 shows characteristics of an effective value current and input power detected by an effective value current detecting means described in the circuit diagram of FIG. 17. FIG.
The horizontal axis represents the rms current, and the vertical axis represents the characteristics with the input power.The input power increases with an increase in the conduction time of the first switching element, that is, an increase in the rms current.
The input power can be controlled with high accuracy by performing feedback based on information on the effective value current.

(Embodiment 7) FIG. 19 shows an example of a circuit diagram of an induction heating cooker according to a seventh embodiment of the present invention. This configuration is different from the circuit configuration of the first embodiment in that the peak current value detection unit 2 detects the peak value of the current flowing through the second reverse conducting diode.
2, which controls the input power by performing feedback based on the information on the peak current value.

FIG. 20 shows an example in which the control means of this embodiment is used.
FIG. 21 shows characteristics of a peak current value and input power detected by peak current value detection means described in the circuit diagram of FIG. 20. FIG.
Represents the characteristics with the horizontal axis representing the peak current value and the vertical axis representing the input power, the increase in the conduction time of the first switching element,
That is, since the input power increases with an increase in the peak current value, the input power can be controlled with high accuracy by performing feedback based on the information on the peak current value.

(Eighth Embodiment) FIG. 21 shows an example of a circuit diagram of an induction heating cooker according to an eighth embodiment of the present invention. In this configuration, the circuit configuration of the first embodiment is provided with an effective value current detection unit 23 that detects an effective value of a current flowing through the second switching element and the second reverse conducting diode. It is also the effective value current of the capacitor, and the input power is controlled by performing feedback based on the information of the effective value current.

Referring to FIG. 22, using the control means of the first embodiment,
FIG. 22 shows an example of the characteristics of the effective value current and the input power detected by the effective value current detection means described in the circuit diagram of FIG. 21. FIG.
2, the horizontal axis represents the effective value current, and the vertical axis represents the characteristics of the input power, the increase of the conduction time of the first switching element,
That is, since the input power increases with an increase in the effective current, the input power can be controlled with high accuracy by performing feedback based on information on the effective current.

In FIG. 23, using the control means of the first embodiment,
FIG. 22 shows an example of the characteristics of the effective value current and the input power detected by the effective value current detection means described in the circuit diagram of FIG. 21. FIG.
3, the horizontal axis represents the rms current and the vertical axis represents the input power, as in FIG. 22. The input power increases as the conduction time of the second switching element decreases, that is, as the rms current decreases. Therefore, the input power can be controlled with high accuracy by performing feedback based on the effective current information.

In FIG. 24, using the control means of this embodiment,
FIG. 22 shows an example of the characteristics of the effective value current and the input power detected by the effective value current detection means described in the circuit diagram of FIG. 21. FIG.
4 shows the characteristics with the effective value current on the horizontal axis and the input power on the vertical axis, as in FIGS. As described in the description of FIGS. 22 and 23, the increase in the conduction time of the first switching element increases the effective current and increases the input power.
Since the conduction time of the second switching element decreases, the effective value current decreases and the input power increases, so the effective value current of the second capacitor is suppressed to a certain value or less, and the input power is controlled while preventing destruction due to heat generation. Becomes possible.

(Embodiment 9) FIG. 25 shows an example of a circuit diagram of an induction heating cooker according to a ninth embodiment of the present invention. In this configuration, a peak current value detecting unit 22 for detecting a peak value of a current flowing through a heating coil is provided in the circuit configuration of the first embodiment, and input power is controlled by performing feedback based on the information on the peak current value. I do.

In FIG. 26, using the control means of this embodiment,
26 shows characteristics of a peak current value and input power detected by peak current value detection means described in the circuit diagram of FIG. FIG.
Represents the characteristics with the horizontal axis representing the peak current value and the vertical axis representing the input power, the increase in the conduction time of the first switching element,
That is, since the input power increases with an increase in the peak current value, the input power can be controlled with high accuracy by performing feedback based on the information on the peak current value.

(Embodiment 10) FIG. 27 shows a tenth embodiment of the present invention.
FIG. 3 is an example of a circuit diagram of the induction heating cooker according to the embodiment. In this configuration, an effective value current detection unit 23 for detecting an effective value of a current flowing through a heating coil is provided in the circuit configuration of the first embodiment, and feedback is performed based on information on the effective value current to reduce input power. Control.

In FIG. 28, using the control means of this embodiment,
28 illustrates an example of characteristics of an effective value current and input power detected by an effective value current detection unit illustrated in the circuit diagram of FIG. 27. FIG.
8, the horizontal axis represents the effective value current, and the vertical axis represents the characteristics of the input power, the increase of the conduction time of the first switching element,
That is, since the input power increases with an increase in the effective current, the input power can be controlled with high accuracy by performing feedback based on information on the effective current.

(Embodiment 11) FIG. 29 shows an eleventh embodiment of the present invention.
FIG. 3 is an example of a circuit diagram of the induction heating cooker according to the embodiment. This configuration is different from the circuit configuration of the first embodiment in that the peak current value detection unit 22 that detects the peak value of the current flowing through the first capacitor is used.
The input power is controlled by performing feedback based on the information on the peak current value.

FIG. 30 shows an example in which the control means of this embodiment is used.
FIG. 29 shows characteristics of a peak current value and input power detected by peak current value detection means described in the circuit diagram of FIG. FIG.
Represents the characteristics with the horizontal axis representing the peak current value and the vertical axis representing the input power, the increase in the conduction time of the first switching element,
That is, since the input power increases with an increase in the peak current value, the input power can be controlled with high accuracy by performing feedback based on the information on the peak current value.

(Embodiment 12) FIG. 31 shows a twelfth embodiment of the present invention.
FIG. 3 is an example of a circuit diagram of the induction heating cooker according to the embodiment. In this configuration, an effective value current detecting means 23 for detecting an effective value of a current flowing through the first capacitor is provided in the circuit configuration of the first embodiment. Control.

In FIG. 32, using the control means of this embodiment,
FIG. 32 shows an example of the characteristics of the effective value current and the input power detected by the effective value current detection means described in the circuit diagram of FIG. 31. FIG.
2 represents a characteristic in which the horizontal axis represents the effective value current and the vertical axis represents the input power, the reduction of the conduction time of the second switching element,
That is, since the input power increases with an increase in the effective current, the input power can be controlled with high accuracy by performing feedback based on information on the effective current.

In FIG. 33, using the control means of this embodiment,
FIG. 32 shows an example of the characteristics of the effective value current and the input power detected by the effective value current detection means described in the circuit diagram of FIG. 31. FIG.
3 represents the characteristic with the abscissa representing the effective value current and the ordinate representing the input power, wherein the conduction time of the first switching element is increased,
That is, since the input power increases with an increase in the effective current, the input power can be controlled with high accuracy by performing feedback based on information on the effective current. Note that the inclination is steeper than when the control unit of the first embodiment is used.

In FIG. 34, using the control means of this embodiment,
FIG. 32 shows an example of the characteristics of the effective value current and the input power detected by the effective value current detection means described in the circuit diagram of FIG. 31. FIG.
4 shows the characteristics with the effective value current on the horizontal axis and the input power on the vertical axis as in FIGS. 32 and 33. As described in the description of FIGS. 32 and 33, the decrease in the conduction time of the second switching element and the increase in the conduction time of the first switching element increase the effective current and increase the input power. As shown in FIG. 34, the conduction time of the second switching element is increased, and the effective value current is greatly reduced as compared with the decrease of the conduction time of the first switching element. It is possible to control the input power while keeping the current below a certain value to prevent destruction due to heat generation.

(Embodiment 13) FIG. 35 shows a thirteenth embodiment of the present invention.
FIG. 3 is a circuit diagram of the induction heating cooker according to the embodiment. In this configuration, the circuit diagram of the first embodiment includes the voltage detecting means 24 at both ends of the first switching element 14, and detects the voltage at both ends to perform feedback to control the input power.

In FIG. 36, using the control means of the first embodiment,
36 shows an example of the characteristics of the voltage between both ends and the input power detected by the voltage detection means between both ends of the first switching element shown in the circuit diagram of FIG. 35. FIG. 36 shows the characteristics with the horizontal axis representing the voltage across the first switching element and the vertical axis representing the input power,
Since the input power increases with a decrease in the conduction time of the second switching element, that is, an increase in the voltage across the first switching element, feedback of the control of the input power is performed based on the information on the voltage across the first switching element. This enables accurate control.

FIG. 37 shows an example in which the control means of this embodiment is used.
36 shows an example of the characteristics of the voltage between both ends and the input power detected by the voltage detection means between both ends of the first switching element shown in the circuit diagram of FIG. 35. In FIG. 37, as shown in FIG. 36, the horizontal axis is the voltage at both ends, and the vertical axis is the input power. As the conduction time of the first switching element increases, the voltage at both ends increases and the input power also increases. The power can be controlled by detecting the voltage between both ends of the first switching element and performing feedback.

(Embodiment 14) FIG. 38 shows a fourteenth embodiment of the present invention.
FIG. 3 is a circuit diagram of the induction heating cooker according to the embodiment. In this configuration, the circuit diagram of the first embodiment includes the voltage detecting means 25 at both ends of the second switching element 17, detects the voltage at both ends, performs feedback, and controls the input power.

In FIG. 39, using the control means of this embodiment,
39 shows an example of the characteristics of the voltage between both ends and the input power detected by the voltage detecting means 25 across the second switching element shown in the circuit diagram of FIG. 38. FIG. 39 shows the characteristics with the horizontal axis representing the voltage across the second switching element and the vertical axis representing the input power, with the decrease in the conduction time of the second switching element, that is, with the increase in the voltage across the second switching element. Since the input power increases, the input power is controlled based on the information on the voltage between both ends of the first switching element, so that accurate control can be performed.

(Embodiment 15) FIG. 40 shows a fifteenth embodiment of the present invention.
FIG. 3 is a circuit diagram of the induction heating cooker according to the embodiment. This configuration is different from the circuit diagram of the first embodiment in that the voltage detection means 24 at both ends of the first switching element 14, the voltage detection means 25 at both ends of the second switching element 17, and the difference between the voltages at both ends detected by each voltage detection means. , Which detects the voltage between both ends of each switching element, obtains the difference between them, performs feedback, and controls the input power.

In FIG. 41, using the control means of this embodiment,
41 shows an example of the difference between the voltage between both ends of each switching element detected by the subtraction means described in the circuit diagram of FIG. 40 and the characteristic of the input power. FIG. 41 shows the characteristics with the horizontal axis representing the difference between the voltages at both ends of the switching elements and the vertical axis representing the characteristics as the input power. The decrease in the conduction time of the second switching element, that is, the decrease in the difference between the voltages across the switching elements, is shown. Accordingly, the input power increases, so that the control of the input power can be performed with high accuracy by performing the feedback based on the information on the voltage difference between both ends of each switching element.

(Embodiment 16) FIG. 42 shows a sixteenth embodiment of the present invention.
FIG. 3 is a circuit diagram of the induction heating cooker according to the embodiment. In this configuration, the circuit diagram of the first embodiment includes the voltage detecting means 24 at both ends of the first capacitor 13, and detects the voltage at both ends to perform feedback to control the input voltage.

FIG. 43 shows an example in which the control means of this embodiment is used.
43 shows an example of the characteristics of the voltage across the terminals and the input power detected by the voltage detecting means between both ends of the first capacitor described in the circuit diagram of FIG. 42. 43, the horizontal axis represents the voltage across the first capacitor,
The vertical axis represents the characteristics as input power, and the conduction time of the second switching element decreases, that is, the input power increases with an increase in the voltage across the first capacitor. By performing feedback based on information on the voltage between both ends, highly accurate control can be performed.

(Embodiment 17) FIG. 44 shows a seventeenth embodiment of the present invention.
FIG. 3 is a circuit diagram of the induction heating cooker according to the embodiment. In this configuration, the circuit diagram of the first embodiment includes the voltage detecting means 24 at both ends of the second capacitor 16, and detects the voltage at both ends to perform feedback to control the input voltage.

FIG. 45 shows an example in which the control means of this embodiment is used.
FIG. 45 shows an example of the characteristics of the voltage between both ends and the input power detected by the voltage detection means between both ends of the second capacitor shown in the circuit diagram of FIG. 44. FIG. 45 shows the voltage across the second capacitor on the horizontal axis,
The vertical axis represents the characteristics as the input power, the input power increases with a decrease in the conduction time of the second switching element, that is, a decrease in the voltage across the second capacitor. By performing feedback based on information on the voltage between both ends, highly accurate control can be performed.

(Embodiment 18) FIG. 46 shows an eighteenth embodiment of the present invention.
FIG. 3 is an example of a circuit diagram of the induction heating cooker according to the embodiment. This configuration includes voltage detecting means at both ends of the first switching element 14, and controls input power based on information of current detecting means for detecting an output current from the DC power supply 11, and at the same time, voltage at both ends of the first switching element is Control is performed so as to be equal to or less than a predetermined value.

FIG. 47 shows an example in which the control means of this embodiment is used.
FIG. 47 shows an example of control means for controlling the characteristics of the input voltage and the voltage between both ends detected by the voltage detection means between both ends of the first switching element shown in the circuit diagram of FIG. 46. FIG. 47 shows the characteristics with the horizontal axis representing the voltage across the first switching element and the vertical axis representing the input power. With the increase in the conduction time of the first switching element, that is, with the increase in the input power, the characteristic of the first switching element is shown. The voltage between both ends increases, and when the voltage between both ends reaches a set value, the conduction time of the second switching element is increased, the voltage between both ends is decreased, and the conduction time of the first switching element is increased again, and the input power is increased. Let it.

(Embodiment 19) FIG. 48 shows a nineteenth embodiment of the present invention.
FIG. 3 is an example of a circuit diagram of the induction heating cooker according to the embodiment. This configuration includes voltage detection means at both ends of the second switching element 17, and controls input power based on information of current detection means for detecting an output current from the DC power supply 11, and at the same time, voltage at both ends of the second switching element is Control is performed so as to be equal to or less than a predetermined value.

In FIG. 49, using the control means of this embodiment,
FIG. 49 illustrates an example of a control unit for controlling the characteristics of the input voltage and the voltage between both ends detected by the voltage detection unit between both ends of the second switching element illustrated in the circuit diagram of FIG. 48. FIG. 47 shows the characteristics with the horizontal axis representing the voltage between both ends of the second switching element and the vertical axis representing the input power. The conduction time of the first switching element increases, that is, the input power increases. The voltage between both ends increases, and when the voltage between both ends reaches a set value, the conduction time of the second switching element is increased, the voltage between both ends is decreased, and the conduction time of the first switching element is increased again, and the input power is increased. Let it.

(Embodiment 20) FIG. 50 shows a twentieth embodiment of the present invention.
FIG. 3 is an example of a circuit diagram of the induction heating cooker according to the embodiment. This configuration includes a voltage detecting means at both ends of the first capacitor 13, and controls the input power based on the information of the current detecting means for detecting the output current from the DC power supply 11, and at the same time, sets the voltage across the first capacitor to a predetermined value. Control is performed as follows.

FIG. 51 shows an example in which the control means of this embodiment is used.
50 shows an example of control means for controlling the characteristics of the input voltage and the voltage at both ends of the first capacitor shown in the circuit diagram of FIG. FIG. 51 shows the characteristics with the horizontal axis representing the voltage across the first capacitor and the vertical axis representing the input power. As the conduction time of the first switching element increases, that is, as the input power increases, the voltage across the first capacitor increases. Increases,
When the voltage at both ends reaches the set value, the conduction time of the second switching element is increased, the voltage at both ends is decreased, and the conduction time of the first switching element is increased again to increase the input power.

Embodiment 21 FIG. 52 shows a twenty-first embodiment of the present invention.
FIG. 3 is an example of a circuit diagram of the induction heating cooker according to the embodiment. This configuration includes means for detecting the voltage across the second capacitor 16 and controls the input power based on the information of the current detecting means for detecting the output current from the DC power supply 11, and at the same time, the voltage across the second capacitor 16 is a predetermined value. Control is performed as follows.

FIG. 53 shows an example in which the control means of this embodiment is used.
52 shows an example of control means for controlling the characteristics of the input voltage and the voltage across the second capacitor detected by the voltage detection means across the second capacitor shown in the circuit diagram of FIG. 52. FIG. 53 shows the characteristics with the horizontal axis representing the voltage across the second capacitor and the vertical axis representing the input power. As the conduction time of the first switching element increases, that is, as the input power increases, the voltage across the second capacitor increases. Increases,
When the voltage at both ends reaches the set value, the conduction time of the second switching element is increased, the voltage at both ends is decreased, and the conduction time of the first switching element is increased again to increase the input power.

[0085]

As is apparent from the above embodiment, according to the first aspect of the present invention, the conduction time of the first switching element is fixed and the conduction time of the second switching element is controlled to control the input power. In order to change, although the voltage across the first switching element rises with an increase in input power,
By the second resonance capacitor and the second switching element,
The voltage of the first switching element is clamped, and it is possible to control the voltage at both ends lower than that of the conventional example in which the second switching element does not operate, so that the first switching element can be converted to a low withstand voltage and low cost component. Is obtained.

According to a second aspect of the present invention, in order to control the input power, the conduction time of the first switching element is changed, and the conduction time of the second switching element is fixed. Although it increases with an increase in input power, it is possible to control the second switching capacitor and the second switching element in a state of being clamped for a certain period of time to convert the first switching element into a low-withstand-voltage and low-cost component. Further, as compared with the invention described in the first aspect, the operating frequency is reduced when the input power is large, so that the effect of reducing the switching loss of the first switching element can be obtained.

According to a third aspect of the present invention, there is provided a current detecting means for detecting an output current of the DC power supply according to the first aspect, and the control circuit according to the first aspect is provided based on information from the current detecting section. Since the control of the input power is performed by using the means of the first and second aspects, the effect that the input power can be controlled with higher accuracy than that of the first and second aspects of the invention can be achieved. Is obtained.

According to a fourth aspect of the present invention, there is provided a frequency detecting means for detecting an operating frequency of a current flowing through the coil according to the first aspect, and the control circuit according to the first aspect detects information from the frequency detecting section. Since the input power is controlled based on the first and second means based on the above, the input power can be controlled more accurately than the first and second aspects of the invention, as in the third aspect. The following effect can be obtained.

According to a fifth aspect of the present invention, there is provided a control circuit as set forth in the first aspect, further comprising a frequency detecting means for detecting an operating frequency of a current flowing through the coil according to the first aspect. Controls the input power within a predetermined operating frequency range based on information from the frequency detection means, so that the input power is controlled without generating harsh sounds while avoiding the natural vibration frequency of the pan serving as a load. The effect that becomes possible is obtained.

According to a sixth aspect of the present invention, there is provided a peak current value detecting means for detecting a peak current value of a current flowing through the first switching element, the first reverse conducting diode, or both of the first switching element and the first reverse conducting diode. The control circuit according to item 1 is
Since the control of the input power is performed using the means of claim 1 and claim 2 based on the information from the peak current value detecting means, the invention according to claim 1 and claim 2 as in claim 3 As a result, the effect that the input power can be controlled with higher accuracy than that of the first embodiment is obtained.

According to a seventh aspect of the present invention, there is provided an effective current detecting means for detecting an effective current of a current flowing through the first switching element, the first reverse conducting diode, or both of the first switching element and the first reverse conducting diode. The control circuit according to the first aspect controls the input power based on the information from the effective value current detection means by using the means of the first and second aspects.
Similarly to the first and second aspects of the present invention, an effect that the input power can be controlled with higher accuracy can be obtained.

According to an eighth aspect of the present invention, there is provided a peak current value detecting means for detecting a peak current value of a current flowing through the second switching element, the second reverse conducting diode, or both of the first switching element and the second reverse conducting diode. The control circuit according to item 1 is
Since the control of the input power is performed using the means of claim 1 and claim 2 based on the information from the peak current value detecting means, the invention according to claim 1 and claim 2 as in claim 3 As a result, the effect that the input power can be controlled with higher accuracy than that of the first embodiment is obtained.

According to a ninth aspect of the present invention, there is provided an effective current detecting means for detecting an effective current of a current flowing through the second switching element, the second reverse conducting diode, or both of the first switching element and the second reverse conducting diode. The control circuit according to the first aspect controls the input power based on the information from the effective value current detection means by using the means of the first and second aspects.
Similarly to the first and second aspects of the present invention, an effect that the input power can be controlled with higher accuracy can be obtained.

According to a tenth aspect of the present invention, an effective value current of a current flowing through the second switching element and the second reverse conducting diode according to the first aspect, that is, an effective value current for detecting an effective value current flowing through the second capacitor is provided. The control circuit according to claim 1, further comprising a detection unit, wherein the control circuit controls the input power while controlling the effective value current to a predetermined value or less based on the information from the effective value current detection unit. Since this is performed using the means of item 2, an effect is obtained in which input power can be controlled while preventing destruction of the second capacitor due to heat generation.

According to an eleventh aspect of the present invention, the control circuit according to the first aspect includes a peak current value detecting means for detecting a peak current value of a current flowing through the coil according to the first aspect. Since the input power is controlled based on the information from the means by using the means of claims 1 and 2, the input power is more accurately input than in the invention of claims 1 and 2, as in claim 3. The effect that power control becomes possible is obtained.

According to a twelfth aspect of the present invention, the control circuit according to the first aspect further comprises an effective value current detecting means for detecting an effective value current of the current flowing through the coil. Since the input power is controlled based on the information from the means by using the means of claims 1 and 2, the input power is more accurately input than in the invention of claims 1 and 2, as in claim 3. The effect that power control becomes possible is obtained.

According to a thirteenth aspect of the present invention, the control circuit according to the first aspect further comprises a peak current value detecting means for detecting a peak current value of a current flowing through the first capacitor. Since the input power is controlled using the means of claim 1 and claim 2 based on the information from the value detection means, the accuracy is higher than that of claim 1 and claim 2 as in claim 3. The effect that the input power can be controlled well is obtained.

According to a fourteenth aspect of the present invention, the control circuit according to the first aspect further comprises an effective value current detecting means for detecting an effective value current of the current flowing through the first capacitor according to the first aspect. Since the input power is controlled based on the information from the current detecting means using the means of claim 1 and claim 2,
As in the case of the third aspect, the effect that the input power can be controlled with higher accuracy than the inventions of the first and second aspects is obtained.

According to a fifteenth aspect of the present invention, the control circuit according to the first aspect further comprises an effective value current detecting means for detecting an effective value current flowing through the first capacitor. The input power is controlled using the means of claims 1 and 2, while controlling the effective value current to be equal to or less than a predetermined value based on information from the means, thereby preventing destruction of the first capacitor due to heat generation. In addition, the effect that the input power can be controlled is obtained.

According to a sixteenth aspect of the present invention, there is provided the first switching element according to the first aspect, further comprising a voltage detecting means, and the control circuit according to the first aspect inputs the voltage based on information from the voltage detecting means. Since power control is performed using the means of claim 1 and claim 2, the effect that input power can be controlled with higher accuracy than the inventions of claim 1 and claim 2 can be achieved, similarly to claim 3. Is obtained.

According to a seventeenth aspect of the present invention, there is provided a second switching element according to the first aspect, further comprising a voltage detecting means, and the control circuit according to the first aspect inputs the voltage based on information from the voltage detecting means. Since power control is performed using the means of claim 1 and claim 2, the effect that input power can be controlled with higher accuracy than the inventions of claim 1 and claim 2 can be achieved, similarly to claim 3. Is obtained.

The invention as set forth in claim 18 is provided with the means for detecting the voltage between both ends of the first switching element, the means for detecting the voltage between both ends of the second switching element, and the subtraction means for obtaining a difference between the respective voltages of both ends. Since the control circuit according to the first aspect controls the input power based on the information from the subtraction means using the means of the first and second aspects, the control circuit according to the first and second aspects has the same features as the first and second aspects. The effect that the input power can be controlled with higher accuracy than the invention described in claim 2 is obtained.

According to a nineteenth aspect of the present invention, there is provided means for detecting a voltage between both ends of the first capacitor according to the first aspect of the present invention.
The control circuit described above controls input power based on information from the voltage detection means using the means of claim 1 and claim 2, so that the control circuit according to claim 1 and claim 2 as in claim 3. The effect that the input power can be controlled with higher accuracy than the invention described in 2 is obtained.

According to a twentieth aspect of the present invention, there is provided means for detecting a voltage between both ends of the second capacitor according to the first aspect of the present invention.
The control circuit described above controls input power based on information from the voltage detection means using the means of claim 1 and claim 2, so that the control circuit according to claim 1 and claim 2 as in claim 3. The effect that the input power can be controlled with higher accuracy than the invention described in 2 is obtained.

According to a twenty-first aspect of the present invention, a voltage detecting means for both ends of the first switching element according to the third aspect is provided, and the control circuit according to the third aspect detects the output current from the DC power supply while detecting the output current from the DC power supply. Since the control is performed so that the voltage is equal to or lower than the predetermined value, an effect that the input power can be controlled while preventing breakdown of the first switching element is obtained.

According to a twenty-second aspect of the present invention, a voltage detecting means for both ends of the second switching element according to the third aspect is provided, and the control circuit according to the third aspect detects the output current from the DC power supply while detecting both ends. Since the control is performed so that the voltage is equal to or lower than the predetermined value, an effect is obtained that the input power can be controlled while preventing the breakdown voltage of the second switching element.

According to a twenty-third aspect of the present invention, there is provided a means for detecting a voltage between both ends of the first capacitor according to the third aspect.
The control circuit described above controls the input voltage while detecting the output current from the DC power supply so that the voltage at both ends is equal to or lower than a predetermined value, thereby preventing the breakdown voltage of the first capacitor and controlling the input power. Is obtained.

According to a twenty-fourth aspect of the present invention, there is provided a means for detecting the voltage between both ends of the second capacitor according to the third aspect.
The control circuit described above controls the input voltage while preventing the breakdown voltage of the second capacitor because the control circuit controls the voltage between both ends to be equal to or less than a predetermined value while detecting the output current from the DC power supply. Is obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an induction heating apparatus according to a first embodiment of the present invention.

FIG. 2 is an operation waveform diagram of each switching element of the induction heating device.

FIG. 3 is a graph showing input power characteristics of the induction heating device.

FIG. 4 is another circuit diagram of the induction heating device.

FIG. 5 is another circuit diagram of the induction heating device.

FIG. 6 is another input power characteristic diagram of the induction heating device.

FIG. 7 is a circuit diagram of an induction heating apparatus according to a second embodiment of the present invention.

FIG. 8 is a characteristic diagram of output current and input power of the induction heating device.

FIG. 9 is a circuit diagram of an induction heating apparatus according to a third embodiment of the present invention.

FIG. 10 is a characteristic diagram of operating frequency and input power of the induction heating device.

FIG. 11 is a characteristic diagram of operating frequency and input power of the induction heating device.

FIG. 12 is a characteristic diagram of another operating frequency and input power of the induction heating device.

FIG. 13 is a circuit diagram of an induction heating apparatus according to a fourth embodiment of the present invention.

FIG. 14 is a characteristic diagram of a peak current value and an input power of the induction heating device.

FIG. 15 is a circuit diagram of an induction heating apparatus according to a fifth embodiment of the present invention.

FIG. 16 is a characteristic diagram of a peak current value and an input power of the induction heating device.

FIG. 17 is a circuit diagram of an induction heating apparatus according to a sixth embodiment of the present invention.

FIG. 18 is a characteristic diagram of an effective value current and an input power of the induction heating device.

FIG. 19 is a circuit diagram of an induction heating apparatus according to a seventh embodiment of the present invention.

FIG. 20 is a characteristic diagram of a peak current value and an input power of the induction heating device.

FIG. 21 is a circuit diagram of an induction heating apparatus according to an eighth embodiment of the present invention.

FIG. 22 is a characteristic diagram of an effective value current and an input power of the induction heating device.

FIG. 23 is a characteristic diagram of another effective value current and input power of the induction heating device.

FIG. 24 is a characteristic diagram of yet another effective value current and input power of the induction heating device.

FIG. 25 is a circuit diagram of an induction heating apparatus according to a ninth embodiment of the present invention.

FIG. 26 is a characteristic diagram of a peak current value and an input power of the induction heating device.

FIG. 27 is a circuit diagram of an induction heating apparatus according to a tenth embodiment of the present invention.

FIG. 28 is a characteristic diagram of an effective value current and input power of the induction heating device.

FIG. 29 is a circuit diagram of an induction heating apparatus according to an eleventh embodiment of the present invention.

FIG. 30 is a characteristic diagram of a peak current value and an input power of the induction heating device.

FIG. 31 is a circuit diagram of an induction heating apparatus according to a twelfth embodiment of the present invention.

FIG. 32 is a characteristic diagram of an effective value current and input power of the induction heating device.

FIG. 33 is a characteristic diagram of another effective value current and input power of the induction heating device.

FIG. 34 is a characteristic diagram of yet another effective value current and input power of the induction heating device.

FIG. 35 is a circuit diagram of an induction heating apparatus according to a thirteenth embodiment of the present invention.

FIG. 36 is a characteristic diagram of voltage between both ends and input power of the induction heating apparatus.

FIG. 37 is a characteristic diagram of another terminal voltage and input power of the induction heating device.

FIG. 38 is a circuit diagram of an induction heating apparatus according to a fourteenth embodiment of the present invention.

FIG. 39 is a characteristic diagram of the voltage between both ends and the input power of the induction heating device.

FIG. 40 is a circuit diagram of an induction heating apparatus according to a fifteenth embodiment of the present invention.

FIG. 41 is a characteristic diagram of a difference between voltages at both ends of the induction heating device and an input power.

FIG. 42 is a circuit diagram of an induction heating apparatus according to a sixteenth embodiment of the present invention.

FIG. 43 is a characteristic diagram of the voltage between both ends and the input power of the induction heating device.

FIG. 44 is a circuit diagram of an induction heating apparatus according to a seventeenth embodiment of the present invention.

FIG. 45 is a characteristic diagram of voltage between both ends and input power of the induction heating apparatus.

FIG. 46 is a circuit diagram of an induction heating apparatus according to an eighteenth embodiment of the present invention.

FIG. 47 is a characteristic diagram of voltage between both ends and input power of the induction heating device.

FIG. 48 is a circuit diagram of an induction heating apparatus according to a nineteenth embodiment of the present invention.

FIG. 49 is a characteristic diagram of voltage between both ends and input power of the induction heating apparatus.

FIG. 50 is a circuit diagram of an induction heating apparatus according to a twentieth embodiment of the present invention.

FIG. 51 is a characteristic diagram of voltage between both ends and input power of the induction heating device.

FIG. 52 is a circuit diagram of an induction heating apparatus according to a twenty-first embodiment of the present invention.

FIG. 53 is a characteristic diagram of voltage between both ends and input power of the induction heating apparatus.

FIG. 54 is a circuit diagram of a conventional induction heating cooking device.

FIG. 55 is an operation waveform diagram of a switching element of the induction heating device.

[Explanation of symbols]

 11, 551 DC power supply 12, 552 Heating coil 13, 553 First capacitor 14, 554 First switching element 15, 555 First reverse conducting diode 16 Second capacitor 17 Second switching element 18 Second reverse conducting diode 19, 559 Control Circuit 20 Current detecting means 21 Frequency detecting means 22 Peak current value detecting means 23 Effective value current detecting means 24,558 Both ends voltage detecting means 25 Both ends voltage detecting means 26 Subtracting means

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hidekazu Yamashita 1006 Kazuma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (24)

[Claims] 1. A coil having one end connected to a DC power supply, a parallel circuit of a first switching element and a first reverse conducting diode connected in series with the coil to the DC power supply, and a resonance with the coil. A first capacitor forming a circuit, and a series circuit including a second capacitor connected in series with a parallel circuit of a second switching element and a second reverse conducting diode connected in parallel to the coil or the first switching element. A control circuit for controlling conduction of the first switching element and the second switching element,
An induction heating device wherein the control circuit alternately controls conduction of the switching elements, fixes a conduction time of a first switching element to control input power, and changes a conduction time of a second switching element. 2. A coil having one end connected to a DC power supply, a parallel circuit of a first switching element and a first reverse conducting diode connected in series with the coil to the DC power supply, and a resonance with the coil. A first capacitor forming a circuit, and a series circuit including a second capacitor connected in series with a parallel circuit of a second switching element and a second reverse conducting diode connected in parallel to the coil or the first switching element. A control circuit for controlling conduction of the first switching element and the second switching element,
An induction heating apparatus, wherein the control circuit alternately controls conduction of the switching elements, changes a conduction time of a first switching element to control input power, and fixes a conduction time of a second switching element. 3. The induction heating apparatus according to claim 1, further comprising current detection means for detecting an output current of the DC power supply, wherein the control circuit controls input power in accordance with an output of the current detection means. 4. The induction heating apparatus according to claim 1, further comprising an operating frequency detecting means for the circuit, wherein the control circuit controls the input power in accordance with an output of the operating frequency detecting means. 5. The apparatus according to claim 1, further comprising means for detecting a frequency of the current flowing through the coil, wherein the control circuit controls the input power within a predetermined frequency range according to the output of the frequency detecting means.
Or the induction heating device according to 2. 6. A control circuit comprising: a peak current value detecting means for the first switching element and / or the first reverse conducting diode; and the control circuit controls input power according to an output of the peak current value detecting means. 3. The induction heating device according to 1 or 2. 7. An effective value current detecting means for the first switching element and / or the first reverse conducting diode, wherein the control circuit controls input power according to an output of the effective value current detecting means. 3. The induction heating device according to 1 or 2. 8. A control device comprising: a peak current value detecting means for the second switching element and / or the second reverse conducting diode; and the control circuit controls input power according to an output of the peak current value detecting means. 3. The induction heating device according to 1 or 2. 9. An effective value current detecting means for the second switching element and / or the second reverse conducting diode, wherein the control circuit controls the input power in accordance with an output of the effective value current detecting means. 3. The induction heating device according to 1 or 2. 10. An effective value current detecting means for a second switching element and a second reverse conducting diode, wherein the control circuit prevents an effective value current of a predetermined value or more from flowing according to an output of the effective value current detecting means. 3. The induction heating device according to claim 1, wherein the input power is controlled. 11. The induction heating apparatus according to claim 1, further comprising a coil peak current value detecting means, wherein the control circuit controls the input power according to an output of the peak current value detecting means. 12. An apparatus for detecting an effective value current of a coil,
3. The induction heating apparatus according to claim 1, wherein the control circuit controls the input power in accordance with an output of the effective value current detection means. 13. The induction heating apparatus according to claim 1, further comprising a peak current value detecting means for the first capacitor, wherein the control circuit controls the input power according to an output of the peak current value detecting means. 14. The induction heating apparatus according to claim 1, further comprising an effective value current detecting means for the first capacitor, wherein the control circuit controls the input power in accordance with an output of the effective value current detecting means. 15. An effective value current detecting means for the first capacitor, wherein the control circuit controls input power so that an effective value current of a predetermined value or more does not flow according to an output of the effective value current detecting means. The induction heating device according to claim 1 or 2, wherein: 16. A control circuit comprising a voltage detecting means at both ends of the first switching element, wherein the control circuit controls an input power so that an effective current not less than a predetermined value does not flow according to an output of the voltage detecting means at both ends. The induction heating device according to claim 1. 17. A control circuit comprising a voltage detecting means at both ends of the second switching element, wherein the control circuit controls the input power so that an effective current of a predetermined value or more does not flow according to the output of the voltage detecting means at both ends. The induction heating device according to claim 1. 18. A control circuit comprising: a voltage detecting means for both ends of the first switching element, a voltage detecting means for both ends of the second switching element, and a subtraction means for calculating a difference between the voltages at both ends. 3. The induction heating apparatus according to claim 1, wherein the input power is controlled in accordance with the input power. 19. The induction heating apparatus according to claim 1, further comprising a voltage detecting means for both ends of the first capacitor, wherein the control circuit controls the input power in accordance with an output of the voltage detecting means for both ends. 20. The induction heating apparatus according to claim 1, further comprising a voltage detecting means for both ends of the second capacitor, wherein the control circuit controls input power according to an output of the voltage detecting means for both ends. 21. The apparatus according to claim 1, further comprising a voltage detecting means for detecting a voltage between both ends of the first switching element, wherein the control circuit controls the input power while maintaining a voltage between both ends of the first switching element at a predetermined voltage or less. Induction heating equipment. 22. The apparatus according to claim 1, further comprising a voltage detecting means for detecting the voltage between both ends of the second switching element, wherein the control circuit controls the input power while maintaining the voltage between both ends of the second switching element at a predetermined voltage or less. Induction heating equipment. 23. The induction system according to claim 1, further comprising a voltage detecting means for detecting the voltage between both ends of the first capacitor, wherein the control circuit controls the input power while maintaining the voltage between both ends of the first capacitor at a predetermined voltage or less. Heating equipment. 24. The induction according to claim 1, further comprising a voltage detecting means for detecting a voltage between both ends of the second capacitor, wherein the control circuit controls the input power while maintaining the voltage between both ends of the second capacitor at a predetermined voltage or less. Heating equipment.