JP2001160484A - Induction heating cooker - Google Patents

Abstract

(57) [Problem] To provide an induction heating cooker capable of heating an aluminum pan and a multilayer pan. A resonance frequency of a resonance current determined by an inductance of a heating coil coupled to a pan and a capacitance of a resonance capacitor compared with driving frequencies of a first switching element and a second switching element. Is set to twice or more. Thus, high-frequency power can be supplied to the pan without changing the switching frequency of the first switching element 6 and the second switching element 7, and the aluminum pan or the multi-layer pan can be heated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating cooker for cooking using induction heating by a high frequency magnetic field.

[0002]

2. Description of the Related Art A conventional induction heating cooker will be described with reference to the drawings. FIG. 13 is a circuit diagram showing a configuration of an example of an induction heating cooker conventionally used.

A power supply 1 is a DC power supply obtained by rectifying a commercial power supply, and has a pulsating current or a smoothed voltage twice the commercial power supply frequency. The power supply 1 supplies high-frequency power to the heating coil 5 through the choke coil 2 and the smoothing capacitor 3 in accordance with the switching operation of the first switching element 6 and the second switching element 7. The high-frequency power supplied to the heating coil 5 is supplied to the pan 8 as a high-frequency magnetic field, and the pan itself generates heat due to the eddy current generated by the high-frequency magnetic field. Here, the pot 8 is usually made of a material having a large specific resistance such as magnetic stainless steel or iron, and an aluminum pot or the like is usually excluded because it cannot be heated.
The current flowing through the heating coil 5 is a resonance current determined by the heating coil 5 and the resonance capacitor 4. The current monitor 9 includes a current transformer or the like, and monitors an input current supplied from the power supply 1. The control means 10 controls the switching time of the first switching element 6 and the second switching element 7 so that the current detected by the current monitor 9 becomes a predetermined current value. Normally, the ON times of the first switching element 6 and the second switching element 7 are the same, and the switching operation is alternately repeated. The first switching element 6 and the second switching element 7 include diodes for power regeneration, and a current is generated when the switching operation of the first switching element 6 and the second switching element 7 is switched. Will flow.

FIG. 12 shows waveforms during operation of the first switching element 6 and the second switching element 7. The control means 10 inputs a drive signal to the gate of the first switching element 6 to make the first switching element 6 conductive, and turns it on. Then, the current Ic1 flows from the smoothing capacitor 3 through the first switching element 6, the heating coil 5, and the resonance capacitor 4 to become a resonance current. After a predetermined ON time has elapsed, the control means 10 turns off the first switching element 6 and subsequently inputs a drive signal to the gate of the second switching element 7 to turn it on.
Is turned on. Then, the current Ic2 flows from the resonance capacitor 4 through the heating coil 5 and the second switching element 7 to become a resonance current.

[0005] By repeating the above operation, a resonance current is supplied to the heating coil 5. Here, the on time of each of the switching elements 6 and 7 is determined by the resonance capacitor 4
Is controlled in a region shorter than the oscillation period of the resonance current determined by the capacitance of the heating coil 5 and the inductance of the heating coil 5. When the cycle of the resonance current matches the cycle of each of the switching elements 6 and 7, the maximum power is generated. Also, this system is characterized in that the maximum voltage of each of the switching elements 6 and 7 matches the voltage of the power supply 1.

[0006]

In such a conventional induction heating cooker, it is difficult to heat an aluminum pan or a multi-layer pan in which aluminum occupies a large part of the thickness of the pan because the specific resistance of the pan itself is low. there were.

As a method of heating an aluminum pan, (1) increasing the ampere-turn of a heating coil,
In other words, there are a method of increasing the number of turns of the heating coil, (2) a method of further increasing the heating frequency, and the like. In this case, problems such as an increase in loss of the switching element and difficulty in cooling the switching element occur.

[0008] The present invention has been made to solve the above problems, and has as its object to provide an induction heating cooker capable of heating an aluminum pan and a multi-layer pan.

[0009]

According to the present invention, there is provided a first switching element and a second switching element which are connected in series with each other, and a first switching element and a second switching element which are connected in series with each other and which are connected in parallel to the second switching element. A heating coil for induction heating and a resonance capacitor connected to the first coil, a control means for receiving a signal from a current monitor for detecting a current flowing to the heating coil, and alternately driving the two switching elements; And the frequency of the resonance current formed by the heating coil and the resonance capacitor is 2 compared to the frequency of the drive signal of the second switching element.
It is an induction heating cooker set to more than double.

Thus, high-frequency power can be supplied to the pan without increasing the switching loss of the switching element, and an induction heating cooker capable of heating an aluminum pan or a multi-layer pan can be realized.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to a first aspect of the present invention, a first switching element and a second switching element are connected in series with each other, and are connected in series with each other and connected in parallel to the second switching element. A heating coil for induction heating and a resonance capacitor, and a control unit that receives a signal from a current monitor that detects a current flowing to the heating coil, and alternately drives the two switching elements. An induction heating cooker wherein a frequency of a resonance current formed by the heating coil and the resonance capacitor is set to be twice or more as compared with a frequency of a drive signal of the second switching element.

In the above embodiment, high-frequency power can be supplied to the pot without increasing the switching loss of the switching element.

[0013] The invention according to claim 2 is based on claim 1.
In the description, the induction heating cooker has a resonance current frequency set to 100 kHz or more.

In the above embodiment, even when the weight of the aluminum pan or the like is light, the floating of the pan is unlikely to occur.

[0015] The invention according to claim 3 is based on claim 1.
Alternatively, the control means is an induction heating cooker for controlling input power by changing the number of times of passing a zero current of a resonance current passing through the second switching element.

In the above embodiment, the range of adjustment of input power is widened.

Further, the invention according to claim 4 is based on claim 1.
Alternatively, the control means is an induction heating cooker for controlling the input power by changing the number of times of passing the zero current of the resonance current passing through the first switching element.

In the above embodiment, the adjustment range of the input power is widened.

According to a fifth aspect of the present invention, in the first or second aspect, the control means performs the zero switching of the resonance current by one switching operation of the first switching element and the second switching element. Is an induction heating cooker that simultaneously changes the number of passing through and controls the input power while keeping the frequency of the drive signal of the switching element constant.

In the above embodiment, it is possible to adjust the input power at a constant frequency of the drive signal of the switching element, and it is possible to suppress the generation of interference noise due to the difference in the drive frequency of the adjacent induction heating cooker. It becomes.

The invention according to claim 6 is based on claim 1.
Alternatively, the control means is an induction heating cooker for controlling input power by changing an ON time of the first switching element.

In the above embodiment, it is possible to adjust the input power while maintaining the number of resonance currents passing the zero current.

The invention according to claim 7 is based on claim 1.
7. The apparatus according to claim 1, further comprising a pan determination unit that detects a type of the pan, a plurality of resonance capacitors, and a switching unit that switches the resonance capacitor, and the control unit is determined by the pan determination unit. This is an induction heating cooker that controls a switching means in accordance with a signal to switch a resonance capacitor and changes the frequency of a resonance current.

In the above embodiment, various kinds of pots can be effectively heated by one kind of heating coil.

Further, the invention according to claim 8 is based on claim 1.
The method according to any one of claims 1 to 7, further comprising pan weight determining means for detecting the weight of the pan, wherein the control means switches the resonance capacitor when the pan weight determining means determines that the pan is lighter than a set value. This is an induction heating cooker that switches and controls the resonance current frequency to be high.

In the above embodiment, the floating of the pot due to the lightness of the pot can be suppressed only when necessary.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an induction heating cooker according to the present invention will be described with reference to FIGS.
This will be described with reference to FIG.

(Embodiment 1) FIG. 1 is a circuit diagram of an induction heating cooker according to an embodiment of the present invention, and FIG. 2 is a waveform diagram of each part of the circuit in the induction heating cooker. is there. According to the present invention, the control means for controlling the switching element doubles the frequency of the resonance current formed by the heating coil and the resonance capacitor as compared with the frequency of the drive signal of the first switching element and the second switching element. The points set above are different from the induction heating cooker of the conventional example shown in FIG. 13, and the other parts having the same structure and the same operation and effect are denoted by the same reference numerals as those of the conventional example, and detailed description is omitted. ,
The different points will be mainly described.

The power supply 1 is a rectified commercial power supply.
It may be used non-smoothly or in a form smoothed by an electrolytic capacitor or the like. A choke coil 2 connected to the positive electrode of the power supply 1 and a smoothing capacitor 3 connected between the other end of the choke coil 2 and the negative electrode of the power supply 1 serve as a supply source for supplying a high-frequency current. The resonance capacitor 4 and the heating coil 5 for induction heating are connected in series with each other, and a heating coil is connected to a common connection point of the first switching element 6 and the second switching element 7 connected in parallel with the smoothing capacitor 3. 5 is connected to the second switching element 7
Is connected to one end of a resonance capacitor 4. Pot 8
Generates heat due to an eddy current generated by receiving a high-frequency magnetic field of the heating coil 5. The current monitor 9 monitors an input current supplied from the power supply 1. The control means 20 inputs the drive signal shown in FIG. 2 to the gate of the first switching element 6 to make the first switching element 6 conductive, and turns it on. Then, the current Ic1 shown in FIG. 2 flows from the smoothing capacitor 3 through the first switching element 6, the heating coil 5, and the resonance capacitor 4 as a resonance current. Next, when the resonance current reaches zero current, the control means 20 turns off the first switching element 6 and then inputs the drive signal shown in FIG. The second switching element 7 is turned on. Then, the current Ic2 shown in FIG. 2 flows from the resonance capacitor 4 through the heating coil 5 and the second switching element 7 as a resonance current. At this time, the conduction time of the second switching element 7 is 以下 or less of the cycle of the resonance current, so that the electric path from the resonance capacitor 4 to the heating coil 5 and the second switching element 7 Thus, an electric circuit for supplying electric power to the heating coil 5 through a diode built in the second switching element 7 is alternately repeated. The control means 20 continues this operation until the current value detected by the current monitor 9 reaches a predetermined value, and then detects the zero current of the second switching element 7 and turns off the second switching element 7. . By repeating this operation, a resonance current is supplied to the heating coil 5, and a high-frequency magnetic field is supplied to the pan 8 from the heating coil 5.
The control means 20 controls the first switching element 6 and the second switching element 7 to perform control according to the input power using a microcomputer or the like. here,
The drive signals of the first switching element 6 and the second switching element 7 are usually 2 in consideration of switching loss and the like.
It is performed at 0 to 30 kHz. On the other hand, the resonance frequency determined by the inductance of the heating coil 5 coupled to the pan 8 and the capacitance of the resonance capacitor 4 is set to 2 times the operating frequency of the first switching element 6 and the second switching element 7.
The constant is set so that a resonance current of twice or more, that is, two or more waveforms flows through the second switching element 7 in one switching operation. This is to increase the skin resistance and increase the switching loss by using the feature that the skin resistance of the pan is proportional to the square root of the frequency when heating an aluminum pan or the like. It is something that will not be done. Also, by using this method,
By increasing the ampere turn that is normally performed, that is, by increasing the diameter of the heating coil 5, it is possible to increase the magnetic flux entering the pan and suppress the increase in the diameter of the heating coil, which is a problem in the heating method.

The operation of the above configuration will be described.
FIG. 2 is a diagram showing waveforms of respective parts in the present embodiment. (A)
Represents the current waveform Ic1 flowing through the first switching element 6,
(B) shows a current waveform I flowing through the second switching element 7.
c2, (c) shows the waveform of the drive signal given from the control means 20 to the gate of the first switching element 6, and (d) shows the waveform of the drive signal given from the control means 20 to the gate of the second switching element 7. Each waveform is shown. From the waveform of the drive signal, it can be seen that a resonance current having a frequency several times the frequency of the drive signal is supplied to the heating coil 5 while the drive frequency of each switching element remains unchanged from the conventional one.

As described above, according to the present embodiment, high-frequency power can be supplied to the pot 8 without increasing the switching loss of the first switching element 6 and the second switching element 7. An induction heating cooker capable of heating a pan or a multi-layer pan can be realized.

(Embodiment 2) FIG. 3 is a waveform diagram of each part of a circuit configuration in an induction heating cooker according to an embodiment corresponding to the second aspect of the present invention, and FIG. 4 is supplied to a heating coil in the induction heating cooker. FIG. 3 is a diagram showing the frequency of a high-frequency magnetic field to be applied.
The present invention differs from the induction heating cooker of the first embodiment shown in FIG. 1 in that the control means sets the frequency of the resonance current determined by the heating coil and the resonance capacitor to 100 kHz or more, and the circuit configuration of FIG. FIG. 3 is the same as FIG. 2 and detailed description is omitted, and different points will be mainly described.

The control means 20 sets the resonance frequency of the resonance current determined by the inductance of the heating coil 5 and the capacitance of the resonance capacitor 4 to 100 kHz or more.

In the above embodiment, the frequency of the resonance current determined by the heating coil 5 and the resonance capacitor 4 is 100 kHz.
With the above setting, even if the weight of the aluminum pan or the like is light, pan floating is unlikely to occur. That is, when heating an aluminum pan or the like, a repulsive force is generated by the magnetic field of the opposite phase generated in the pan and the magnetic field from the heating coil 5, and this is a phenomenon that occurs due to the lightness of the pan itself being added thereto. As shown in (1), the buoyancy decreases as the frequency of the high-frequency magnetic field supplied to the heating coil 5 increases. Therefore, in this embodiment, the resonance frequency of the resonance current is set to 100 kHz.
By setting as described above, the problem of pan floating is solved.

As described above, according to the present embodiment, even when the weight of an aluminum pan or the like is small, it is difficult for the pan to float, and a highly safe induction heating cooker can be realized.

(Embodiment 3) FIG. 5 is a waveform diagram of each part of a circuit configuration in an induction heating cooker according to an embodiment corresponding to the third aspect of the present invention. The present invention is characterized in that the control means controls the input power by controlling the number of resonance currents flowing when the second switching element conducts, passing through zero current.
Unlike the induction heating cooker of the first embodiment shown in FIG.
Are the same, detailed description is omitted, and different points will be mainly described.

The control means 20 receives a current signal detected by the current monitor 9 and flowing when the second switching element 7 is turned on, and controls the number of resonance currents flowing when the second switching element 7 is turned on and passing the zero current. Thus, the input power is controlled.

In the above embodiment, the control means 20 receives the current signal detected by the current monitor 9 and flowing when the second switching element 7 is turned on, and passes the zero current of the resonance current flowing when the second switching element 7 is turned on. Since the input power is controlled by controlling the number of resonance currents, the number passing through the zero current of the resonance current is small as shown in FIG.
That is, the higher the frequency of the drive signal, the greater the input power. Further, in this configuration, as shown in FIG. 5A, the controllability becomes better as the number of resonance currents passing through the zero current at the rated power increases, so that effective control is performed when the resonance current exceeds 100 kHz. It is a method. That is,
It becomes possible to control to change the input power in accordance with the cooking of the food.

As described above, according to the present embodiment, the range of input power adjustment is widened, and an induction heating cooker with excellent controllability can be realized.

(Embodiment 4) FIG. 6 is a waveform diagram of each part of a circuit configuration in an induction heating cooker according to an embodiment corresponding to the fourth aspect of the present invention. The present invention is characterized in that the control means controls the input power by controlling the number of resonance currents flowing when the first switching element is turned on, passing through zero current.
Unlike the induction heating cooker of the first embodiment shown in FIG.
Are the same, detailed description is omitted, and different points will be mainly described.

The control means 20 receives the current signal detected by the current monitor 9 and flowing when the first switching element 6 is turned on, and controls the number of resonance currents flowing when the first switching element 6 is turned on and passing the zero current. Thus, the input power is controlled.

In the above embodiment, the control means 20 receives the current signal detected by the current monitor 9 and flowing when the first switching element 6 is turned on, and passes the zero current of the resonance current flowing when the first switching element 6 is turned on. Since the input power is controlled by controlling the number of resonance currents, the smaller the number of resonance currents caused by the current flowing through the first switching element 6 as shown in FIG. Is higher, the input power is higher. Further, in this configuration, as shown in FIG. 6B, as the number of passing the zero current of the resonance current at the rated power increases, the input power decreases and the controllability improves, so that the resonance current exceeds 100 kHz. This is an effective control method in cases. That is, control for changing the input power in accordance with the cooking of the food can be performed.

As described above, according to the present embodiment, the range of adjustment of the input power is widened, and an induction heating cooker with excellent controllability can be realized.

(Embodiment 5) FIG. 7 is a waveform diagram of each part of a circuit configuration in an induction heating cooker according to an embodiment corresponding to the fifth aspect of the present invention. According to the present invention, the control means simultaneously controls the number of resonance currents flowing when the first switching element and the second switching element pass through zero current, and keeps the frequency of the drive signal of the switching element constant. The point that the input power is controlled as it is is different from the induction heating cooker of the first embodiment shown in FIG. 1, and the circuit configuration in FIG. 1 is the same, detailed description is omitted, and different points will be mainly described.

The control means 20 receives a current signal detected by the current monitor 9 and flowing when the first switching element 6 and the second switching element 7 are turned on, and controls the first switching element 6 and the second switching element 7. The configuration is such that the number of resonance currents flowing at the time of conduction, passing through zero current, is controlled, and the input power is controlled while keeping the frequency of the drive signal of the switching element constant.

In the above embodiment, the control means 20 receives a current signal detected by the current monitor 9 and flowing when the first switching element 6 and the second switching element 7 are turned on, and receives the first switching element 6 and the second switching element 6. By controlling the number of resonance currents flowing when the switching element 7 passes through the zero current to control the input power while keeping the frequency of the drive signal of the switching element constant, the input power is mainly the second power. Since it is determined by the conduction time of the switching element 7, as shown in FIG. 7B, the smaller the number of resonance currents passing through the second switching element 7 passing through the zero current, the larger the input power becomes. Further, in this configuration, as shown in FIG. 7A, as the number of passing the zero current of the resonance current at the rated power increases, the input power decreases and the controllability improves. It becomes possible to adjust the input power at a constant frequency of the drive signal of the switching element, and to control the drive signal of the adjacent induction heating cooker (the form in which the heating coil is juxtaposed adjacent to one cooker body). It is possible to suppress the generation of interference noise due to the difference in frequency, and to realize an induction heating cooker with low noise.

(Embodiment 6) FIG. 8 is a waveform diagram of each part of a circuit configuration in an induction heating cooker according to an embodiment corresponding to the sixth aspect of the present invention. The present invention differs from the induction heating cooker of the first embodiment shown in FIG. 1 in that the control means controls the input power by changing the ON time of the first switching element, and the circuit configuration in FIG. 1 is the same. A detailed description is omitted, and different points are mainly described.

The control means 20 includes the first switching element 6
The input power is controlled by changing the ON time of the power supply.

In the above embodiment, the control means 20 controls the input power by changing the conduction time of the first switching element 6, that is, when the first switching element 6 is conducting, the control means 20 stores the electric power in the resonance capacitor 4. By controlling the amount of charge applied, the amount of power is controlled when the second switching element 7 is turned on. As shown in FIG. 8B, the control of the input power by this configuration has no limitation when the first switching element 6 is turned off, and allows fine control of the input power, and is excellent in controllability. In addition, as shown in FIG. 8A, the input power increases as the conduction time of the first switching element 6 increases.

As described above, according to this embodiment, the range of adjustment of the input power is widened, and an induction heating cooker with excellent controllability can be realized.

(Embodiment 7) FIG. 9 is a circuit diagram of an induction heating cooker according to an embodiment of the present invention, and FIG. 10 is a waveform diagram of a current flowing through a switching element in the induction heating cooker. FIG. The present invention differs from the induction heating cooker of the first embodiment in that the capacity of the resonance capacitor connected in series with the heating coil is switched in order to change the frequency of the resonance current according to the type of the pan. Parts having the same structure and operation and effect other than those described above are denoted by the same reference numerals as those in FIG. 1, and detailed description thereof will be omitted.

The three resonance capacitors 4 are connected in parallel, and a common connection point is connected to the heating coil 5. And 1
Reference numeral 1 denotes switching means such as a switch connected to two of the resonance capacitors 4 for switching the capacitance. Numeral 12 denotes a pan determining means for detecting the type of the pan, and transmits the detected determination signal to the control means 20a. The control means 20a controls the switching means 11 in accordance with the signal determined by the pan determination means 12, switches the capacity of the resonance capacitor 4, changes the frequency of the resonance current, and controls the input power.

In the above embodiment, when the pot 8 is made of magnetic stainless steel or iron, it is desirable that the frequency of the resonance current be lower than the frequency of the drive signal of the switching element as in the conventional example. This is because the heating coil 5
Loss caused by the skin effect is increased due to the skin effect.
Is iron or the like, it is possible to cause the pot to generate heat sufficiently with the specific resistance at the frequency of the drive signal.

On the other hand, when the pan 8 is an aluminum pan or a multi-layer pan, it is necessary to supply a resonance current several times higher than the frequency of the drive signal as described in the first embodiment. Therefore, it is effective to change the frequency of the resonance current depending on the material of the pan, and to create a resonance current corresponding to the pan 8. In addition, in the case of this configuration, there is no need to switch the heating coil 5 which is performed by heating the conventional aluminum pan. When the pan 8 is an iron pan or the like, the value of the resonance capacitor 4 is increased because the resonance frequency is low, and when the pan 8 is an aluminum pan, the value of the resonance capacitor 4 is reduced. Thus, FIGS. 10A and 10B show waveforms of the current flowing through the switching element when the pan changes. The most effective resonance current can be selected by selecting the optimum resonance capacitor 4 according to the type of the pot.

It should be noted that the pan determining means 12 in the above embodiment is used.
Various methods are conceivable, such as detection from changes in impedance or frequency of resonance current viewed from the heating coil 5 of the pan, but any method may be used as long as the initial purpose is achieved.

As described above, according to the present embodiment, it is possible to effectively heat various pans with one type of heating coil, which is smaller than a conventional induction heating cooker which is also used for heating an aluminum pan. This realizes an induction heating cooker.

(Eighth Embodiment) FIG. 11 is a circuit diagram of an induction heating cooker according to an eighth embodiment of the present invention. The induction heating cooker according to the first and seventh embodiments is characterized in that the present invention switches the capacity of the resonance capacitor connected in series with the heating coil in order to change the frequency of the resonance current according to the weight of the pan. Unlike FIG. 1 and FIG.
The detailed description is omitted by attaching the same reference numerals as in FIG.

Reference numeral 13 denotes a pan weight discriminating means for detecting the weight of the pan, and transmits a signal of the detected weight discrimination to the control means 20b. And the control means 20b is the pan weight discriminating means 13
The switching means 11 is controlled in accordance with the signal determined by the above to switch the resonance capacitor 4 to change the frequency of the resonance current.

In the above embodiment, when the pan 8 is an aluminum pan, a repulsive force is generated from the opposite phase magnetic field generated by the pan and the magnetic field from the heating coil 5, and the light element of the pan itself is added to the repulsive force. A floating phenomenon occurs. For this purpose, it is effective to increase the frequency of the high frequency magnetic field supplied to the heating coil 5 to reduce the buoyancy as shown in FIG. However, increasing the frequency of the resonance current leads to an increase in the loss of the heating coil 5. Therefore, in this embodiment, the weight of the pan is detected by the pan weight discriminating means 13, and only when the weight of the pan is less than a certain value, the capacitance of the resonance capacitor 4 is switched by the switching means 11 to increase the frequency of the resonance current. This is to prevent the floating of the pot.

It should be noted that the pan weight discriminating means 13 may be of various types such as a weight sensor or detection of the instant of pan floating, and any type may be used as long as the initial purpose is achieved.

As described above, according to the present embodiment, it is possible to suppress the floating of the pot due to the lightness of the pot only when necessary, thereby realizing a highly safe induction heating cooker.

[0062]

As apparent from the above embodiment, claim 1
According to the invention, high-frequency power can be supplied to the pan without increasing the loss of the first switching element and the second switching element, and induction heating cooking capable of heating an aluminum pan or a multilayer pan is possible. Can be realized.

Further, according to the second aspect of the present invention, even when the weight of an aluminum pan or the like is light, the floating of the pan is unlikely to occur, and a highly safe induction heating cooker can be realized.

According to the third or fourth aspect of the present invention, the range of input power adjustment is widened, and an induction heating cooker with excellent controllability can be realized.

Further, according to the fifth aspect of the invention, it is possible to adjust the input power at a constant frequency of the drive signal of the switching element, and the interference sound caused by the difference in the frequency of the drive signal of the adjacent induction heating cooker. Can be suppressed, and an induction heating cooker with less noise can be realized.

According to the sixth aspect of the present invention, the input power can be adjusted while maintaining the number of resonance currents passing the zero current, and the induction heating is excellent in controllability over a wide input power adjustment range. A cooker can be realized.

According to the seventh aspect of the present invention, it is possible to effectively heat various pans with one type of heating coil, and to reduce the size compared to a conventional induction heating cooker that also serves as an aluminum pan. Can be planned.

According to the eighth aspect of the present invention, it is possible to suppress the floating of the pot due to the lightness of the pot only when necessary, thereby improving the safety.

[Brief description of the drawings]

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

FIG. 2 is a waveform diagram of each part of a circuit configuration in the induction heating cooker.

FIG. 3 is a waveform diagram of each part of a circuit configuration in an induction heating cooker according to a second embodiment of the present invention.

FIG. 4 is a diagram showing frequency characteristics of a high-frequency magnetic field supplied to a heating coil in the induction heating cooker.

5A is a waveform diagram of a current flowing through a switching element in an induction heating cooker according to a third embodiment of the present invention. FIG. 5B is a waveform diagram of a current flowing through a switching element in the induction heating cooker.

6A is a waveform diagram of a current flowing through a switching element in an induction heating cooker according to a fourth embodiment of the present invention. FIG. 6B is a waveform diagram of a current flowing through a switching element in the induction heating cooker.

7A is a waveform diagram of a current flowing through a switching element in an induction heating cooker according to a fifth embodiment of the present invention. FIG. 7B is a waveform diagram of a current flowing through a switching element in the induction heating cooker.

8A is a waveform diagram of a current flowing through a switching element in an induction heating cooker according to a sixth embodiment of the present invention. FIG. 8B is a waveform diagram of a current flowing through a switching element in the induction heating cooker.

FIG. 9 is a circuit configuration diagram of an induction heating cooker according to a seventh embodiment of the present invention.

FIG. 10A is a waveform diagram of a current flowing through a switching element in the induction heating cooker. FIG. 10B is a waveform diagram of a current flowing through a switching element in the induction heating cooker.

FIG. 11 is a circuit diagram of an induction heating cooker according to an eighth embodiment of the present invention.

FIG. 12 is a waveform diagram of each part of a circuit configuration in a conventional induction heating cooker.

FIG. 13 is a circuit diagram showing the induction heating cooker.

[Explanation of symbols]

 Reference Signs List 4 resonance capacitor 5 heating coil 6 first switching element 7 second switching element 9 current monitor 11 switching means 12 pan discriminating means 13 pan weight discriminating means 20, 20a, 20b control means

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Izumi Hirota 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. F term (reference) 3K051 AA03 AA07 AB05 AC07 AC09 AC12 AC35 AC39 AC52 AD07 AD09 AD10 AD13 AD23 AD25 AD32 AD39 BD07 CD09 CD13 CD43

Claims (8)

[Claims] A first switching element and a second switching element connected in series to each other; a heating coil and a resonance capacitor for induction heating connected in series to each other and connected in parallel to the second switching element; A signal is received from a current monitor that detects a current flowing to the heating coil, and a control unit that drives the two switching elements alternately is provided, compared with a frequency of a drive signal of the first switching element and the second switching element. The frequency of the resonance current formed by the heating coil and the resonance capacitor is 2
Induction heating cooker set to more than double. 2. The induction heating cooker according to claim 1, wherein the frequency of the resonance current is set to 100 kHz or more. 3. The induction heating cooker according to claim 1, wherein the control means controls the input power by changing the number of times the resonance current passing through the second switching element passes through zero current. 4. The induction heating cooker according to claim 1, wherein the control means controls the input power by changing the number of times the resonance current passing through the first switching element passes through zero current. 5. The control means simultaneously changes the number of resonance currents passing through the first switching element and the second switching element passing through zero current, and keeps the frequency of the drive signal of the switching element constant while inputting. The induction heating cooker according to claim 1 or 2, which controls electric power. 6. The induction heating cooker according to claim 1, wherein the control means controls the input power by changing an ON time of the first switching element. 7. A pan determining means for detecting the type of the pan, a plurality of resonance capacitors, and a switching means for switching between the resonance capacitors, wherein the control means controls the switching means in accordance with a signal determined by the pan determining means. The induction heating cooker according to any one of claims 1 to 6, wherein the induction heating cooker is controlled to switch a resonance capacitor to change a frequency of a resonance current. 8. A pan weight judging means for detecting the weight of the pan, wherein the control means switches the resonance capacitor to control the frequency of the resonance current to be higher when the pan weight judging means judges that the pan is lighter than the set value. The induction heating cooker according to any one of claims 1 to 7, wherein