JPH0817567A - Heating cooker - Google Patents

Abstract

(57) [Abstract] [Purpose] The detection voltage of the optimum voltage for processing the detection signal is obtained by indirectly detecting the detection voltage corresponding to the collector-emitter voltage of the switching element by using the magnetic detection means. And stable operation of the high-frequency heating device can be obtained, and the loss can be reduced by reducing the number of heat-generating components. A rectifying / smoothing circuit 2, a resonance circuit having one end connected to one output-side end of the rectification smoothing circuit 2, and a resonance circuit connected between the other end of the resonance circuit and the other output-side end of the rectification / smoothing circuit 2. The switching element and the transformer 3 or the inductor 200 are arranged in the vicinity of the switching element 4 to detect the leakage magnetic flux.
The magnetic detection means 7 outputs a detection signal corresponding to the applied voltage and the drive control means 8 drives the switching element 4 based on the detection signal from the magnetic detection means 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating cooker, and more particularly to a control for maintaining safety and stability of a switching element for generating a high frequency power source and operating it stably.

[0002]

2. Description of the Related Art FIG. 13 shows, for example, Japanese Examined Patent Publication No. 60-1458.
It is a circuit diagram which shows the structure of the conventional heating cooker shown by the 5th publication, and this shows the induction heating cooker. This heating cooker includes a rectifying / smoothing circuit 2 for rectifying and smoothing a commercial AC power supply 1, a switching element 4, a diode 5,
The resonance capacitor 6, the resonance inductor 200, and the timer circuit 201 are provided. Next, the operation of the conventional heating cooker will be described. First, the commercial AC power supply 1 is rectified by the rectifying / smoothing circuit 2, and the smoothed DC is turned on / off by the switching element 4 which is driven and controlled by the timer circuit 201, whereby the resonance capacitor 6 and the resonance inductor 2
00 forms a parallel resonance circuit, and an alternating current having the resonance frequency flows through the resonance inductor 200. Due to the electromagnetic induction effect of this alternating current, an eddy current flows in the cooking pan via the insulating plate. The cooking pot is heated by this eddy current and the electric resistance of the cooking pot itself.

In this conventional example, the timer circuit 201 detects a voltage corresponding to the voltage generated between the collector and the emitter of the switching element 4. If the timer circuit 201 drives the switching element 4 and turns on the switching element 4 before the collector-emitter voltage of the switching element 4 reaches 0 [V], the switching element 4 is turned on. Since a loss occurs during the period from when the state becomes the collector-emitter voltage to 0 [V], the timer circuit 201 detects the collector-emitter voltage of the switching element 4 and sets 0 [V].
This is because the switching element 4 is driven within a certain period of time after it is detected that

Further, the high-frequency heating device uses the same voltage resonance circuit as the induction heating cooker, and among the above-mentioned operations,
Instead of the resonance inductor 200, the primary side of the leaky transformer forms a parallel resonant circuit, and the same operation as the induction heating cooker is performed except that an AC current flows and the secondary side is rectified to drive the magnetron. In addition, the resonance inductor 200
Also in the portion that detects the voltage across both ends of the, the conventional high-frequency heating device directly detects the collector-emitter voltage of the switching element 4 by the voltage detection means, and sends a detection signal to the drive control circuit that drives the switching element 4, Although the drive control circuit drives the switching element 4 at the optimum timing, it is the same as the induction heating cooker in terms of the purpose of detection and direct detection.

[0005]

As described above, in the conventional heating device, in order to reduce the switching loss of the switching element, after the collector-emitter voltage of the switching element reaches 0 [V], A high frequency pulse voltage for turning on the switching element is applied to the gate of the switching element. At this time, since the collector-emitter voltage of the switching element was directly detected from the collector terminal, the detection voltage was too high, and a voltage dividing element for detecting the voltage was required. The element becomes a heat-generating component, and the power source of the drive control circuit that drives the switching element to generate a high-frequency pulse voltage uses a rectified commercial AC power source or DC from a rectifying / smoothing circuit. Also, an element for dividing the voltage is required, and these elements are heat generating parts. Then, there is a problem that the loss of the heating cooker becomes large due to these heat-generating components.

When the power source of the drive control circuit for driving the switching element is supplied from the operation control board power source transformer of the heating cooker to reduce the number of heat-generating components, the drive control circuit and the switching element are grounded differently. Therefore, in the case of directly detecting the collector voltage of the switching element, it is necessary to provide an insulating means at the interface between the two. Depending on the insulating means used, the voltage corresponding to the detected collector-emitter voltage causes a delay with respect to the actual collector-emitter voltage, and the degree of the delay cannot be controlled. However, there is a problem that the switching element cannot be controlled accurately because of the variation.

The present invention has been made to solve the above problems, and a magnetic detection means is used as a collector-emitter voltage detection means of a switching element to detect the collector-emitter voltage of the switching element. By indirectly detecting the detection voltage corresponding to, the detection voltage of the optimum voltage can be obtained when processing the detection signal, and the stable operation of the high frequency heating device can be obtained, and the number of heat-generating components can be reduced. The purpose is to reduce the loss due to.

[0008]

A heating cooker according to a first aspect of the present invention comprises a rectifying / smoothing circuit for rectifying and smoothing a commercial AC power source,
A switching element that converts the output of the rectifying / smoothing circuit to high frequency, supplies high frequency power to the magnetron via a transformer, or supplies high frequency power to the inductor, and is arranged in the vicinity of the transformer or inductor. A magnetic detection unit that detects the leakage magnetic flux from the magnetic field and outputs a detection signal corresponding to the voltage applied to the switching element; and a drive control unit that drives the switching element based on the detection signal from the magnetic detection unit. is there.

The heating cooker according to the second aspect of the present invention converts the output of the rectifying and smoothing circuit for rectifying and smoothing the commercial AC power source into a high frequency, and supplies the magnetron with the high frequency power through the transformer. Or, it is arranged near the switching element that supplies high frequency power to the inductor and the transformer or inductor, detects the leakage magnetic flux from the transformer or inductor, and outputs the detection signal when the voltage applied to the switching element becomes zero. And a drive control means for driving the switching element based on a detection signal from the magnetic detection means.

A heating cooker according to a third aspect of the present invention, a rectifying and smoothing circuit for rectifying and smoothing a commercial AC power source, converts the output of the rectifying and smoothing circuit into high frequency, and supplies high frequency power to a magnetron through a transformer. Alternatively, a switching element that supplies high-frequency power to the inductor and a transformer or inductor that are placed in the vicinity of the inductor detect the leakage flux from the transformer or inductor, detect the voltage applied to the switching element, and detect a delay for a predetermined time. A magnetic detection unit that outputs a signal and a drive control unit that drives the switching element based on the detection signal from the magnetic detection unit are provided.

A heating cooker according to a fourth aspect of the present invention is a rectifying / smoothing circuit for rectifying and smoothing a commercial AC power source, and converts the output of the rectifying / smoothing circuit into a high frequency to supply high frequency power to a magnetron through a transformer, or It is placed in the vicinity of the switching element that supplies high frequency power to the inductor and the transformer or inductor, detects the leakage magnetic flux from the transformer or inductor, the applied voltage of the switching element becomes zero, and the detection signal is output after a lapse of a predetermined time. The magnetic detection means for outputting and the drive control means for driving the switching element based on the detection signal from the magnetic detection means are provided.

In the heating cooker according to the fifth aspect of the present invention, the drive control means is further supplied with power from a cooking control board for controlling the cooker. In the heating cooker according to the sixth aspect of the invention, the magnetism detecting means has a spiral pattern wiring formed on the substrate.

[0013]

In the first aspect of the invention, the rectifying and smoothing circuit is used.
The commercial AC power supply is rectified and smoothed, and the output of the rectification and smoothing circuit is converted to a high frequency by the switching element, and the high frequency power is supplied to the magnetron through the transformer or the high frequency power is supplied to the inductor. Leakage magnetic flux from the transformer or inductor is detected by the magnetic detection means arranged in the vicinity, and a detection signal corresponding to the voltage applied to the switching element is output, and the drive control means is based on the detection signal from the magnetic detection means. Then, the switching element is driven.

In the second invention, the commercial AC power supply is rectified and smoothed by the rectifying and smoothing circuit, the output of the rectifying and smoothing circuit is converted into a high frequency by the switching element, and the high frequency power is supplied to the magnetron through the transformer. , Or high-frequency power is supplied to the inductor, and the magnetic flux detecting means arranged near the transformer or inductor detects the leakage magnetic flux from the transformer or inductor and detects when the voltage applied to the switching element becomes zero. Signal is output,
The drive control means drives the switching element based on the detection signal from the magnetic detection means.

In the third invention, the commercial AC power supply is rectified and smoothed by the rectifying and smoothing circuit, the output of the rectifying and smoothing circuit is converted into a high frequency by the switching element, and the high frequency power is supplied to the magnetron through the transformer. , Or high frequency power is supplied to the inductor, the magnetic flux detecting means arranged near the transformer or the inductor detects the leakage magnetic flux from the transformer or the inductor, which corresponds to the voltage applied to the switching element and for a predetermined time. The delayed detection signal is output, and the drive control unit drives the switching element based on the detection signal from the magnetic detection unit.

In the fourth invention, the commercial AC power supply is rectified and smoothed by the rectifying and smoothing circuit, the output of the rectifying and smoothing circuit is converted into a high frequency by the switching element, and the high frequency power is supplied to the magnetron through the transformer. , Or high frequency power is supplied to the inductor, the magnetic flux detecting means arranged near the transformer or inductor detects the leakage magnetic flux from the transformer or inductor, the applied voltage to the switching element becomes zero, and the predetermined time elapses. After that, a detection signal is output, and the drive control means drives the switching element based on the detection signal from the magnetic detection means.

In the fifth invention, the drive control means is
Power is supplied from the cooking control board that controls the cooking device. In the sixth invention, the magnetic detection means has a spiral pattern wiring formed on the substrate.

[0018]

【Example】

Example 1. FIG. 1 is a circuit diagram showing the configuration of a high frequency heating apparatus according to an embodiment of the present invention. In the figure, 1 is a commercial AC power supply, 2 is a rectifying / smoothing circuit for rectifying and smoothing AC from the commercial AC power supply, 3 is a leakage transformer connected to the output side of the rectifying / smoothing circuit 2, and 4 is a leakage transformer 3. A switching element connected in series to the secondary side, 5 a diode connected in anti-parallel to the switching element 4, 6 a resonant capacitor connected in parallel to the primary side of the leakage transformer 3, and 7 a leakage transformer 3
In the vicinity of, the magnetic detection means provided at a location where the time when the collector-emitter voltage of the switching element 4 reaches 0 [V] can be accurately detected, and 8 is a switching element based on the detection signal from the magnetic detection means 7. 4 is a drive control circuit for driving the power source 4, and its power source is supplied from the commercial AC power source 1 or the rectifying / smoothing circuit 2. Reference numeral 9 is a voltage doubler rectifier circuit connected to the secondary side of the leakage transformer 3, and 10 is a magnetron connected to the output side of the voltage doubler rectifier circuit 9.

Next, the operation of this embodiment will be described. First, the rectifying / smoothing circuit 2 rectifies and smoothes the AC of the commercial AC power supply 1 and outputs a DC power supply, and this DC power supply is input to the primary side of the leakage transformer 3. In addition, 1 of the leakage transformer 3
The switching element 4 is connected in series to the circuit on the next side,
The resonance capacitor 6 is connected in parallel, a high-frequency pulse signal is sent from the drive control circuit 8 to the base of the switching element 4, the switching element 4 is turned on / off at the high frequency, and the capacitance of the resonance capacitor 6 is increased. A parallel resonance circuit is formed by the inductance of the primary side of the leakage transformer 3, and the AC power supply of the resonance frequency is applied to the primary side of the leakage transformer 3.

In response to this, a high voltage is generated on the secondary side of the leakage transformer 3, the high voltage is input to the voltage doubler rectifier circuit 9, and the voltage doubler rectifier circuit 9 further boosts it. , And rectify and send to the magnetron 10. Then, the magnetron 10 receives the high voltage applied from the voltage doubler rectifier circuit 9,
The filament of the magnetron 10 is oscillated by a high-frequency power source supplied from the tertiary winding of the leakage transformer 3, and outputs microwaves to heat the food to be cooked or the like.

Further, the magnetic detection means 7 detects a voltage corresponding to the collector-emitter voltage of the switching element 4 by the leakage magnetic flux of the leakage transformer 3 and issues a detection signal. The drive control circuit 8 detects the timing at which the collector-emitter voltage of the switching element 4 becomes 0 [V] based on the signal, and outputs to the switching element 4 a high-frequency pulse signal that turns on at a timing at which no loss occurs in the switching element 4. to be sending.

In this embodiment, the collector-emitter voltage of the switching element 4 is indirectly detected by the leakage magnetic flux of the leakage transformer 3, so that it is processed by the drive control circuit 8 as a voltage detection signal. An optimum signal level can be obtained, and an element for lowering the voltage as in the case of directly detecting the voltage from the collector of the switching element 4 is not required, so that heat-generating components can be reduced and loss can be reduced. Becomes

Embodiment 2 FIG. In this embodiment, the magnetic detection means 7 of the first embodiment is composed of an inductance. FIG. 2 is a circuit diagram showing the configuration of the high frequency heating apparatus of this embodiment,
FIG. 3 is a schematic diagram when an inductance element is used for the inductance. In FIG. 2, reference numeral 11 is an inductance, and the other configurations are similar to those of the first embodiment. 3, 12 is an inductance element which is an example of the inductance 11 of FIG. 2, 13 is a circuit board of a high frequency heating device, and the inductance element 12 is a circuit board 13 near the leakage transformer 3 as shown in FIG. Is installed in the vehicle and the leakage magnetic flux of the leakage transformer 3 is detected.

Next, the operation of this embodiment will be described. First, the inductance 11 detects the voltage corresponding to the collector-emitter voltage of the switching element 4 by the induced electromotive force generated in the inductance 11 by the leakage magnetic flux of the leakage transformer 3. And the inductance 1
1 transmits the generated induced electromotive force to the drive control circuit 8, and the drive control circuit 8 detects the timing at which the collector-emitter voltage of the switching element 4 becomes 0 [V], and no loss occurs in the switching element 4. A high frequency pulse signal for turning on the switching element 4 at a timing is sent.

In this embodiment, since the collector-emitter voltage of the switching element 4 is indirectly detected by the leakage magnetic flux of the leakage transformer 3, it can be processed by the drive circuit 8 as a voltage detection signal. An optimum signal level can be obtained, an element for reducing the voltage as in the case of directly detecting the voltage from the collector of the switching element 4 is not necessary, heat-generating parts can be reduced, and loss can be reduced. Become.

Example 3. In this embodiment, the magnetic detecting means 7 of the first embodiment is constituted by a spiral pattern wiring printed on a circuit board. FIG. 4 is an explanatory diagram for explaining the spiral pattern wiring printed on the circuit board. In the figure, 14 is a spiral pattern wiring printed on the substrate, 15 is a conducting wire passing through the back side of the circuit board 13, and 16 is a circuit pattern.

Next, the operation of this embodiment will be described. The wiring of the spiral pattern 14 of this embodiment is formed in the vicinity of the leakage transformer 3, and an induced electromotive force is generated in the pattern 14 by the leakage magnetic flux of the leakage transformer 3, and the induced electromotive force causes a switching element. The voltage corresponding to the collector-emitter voltage of 4 is detected.
In this embodiment, since the inductance printed on the circuit board 13 is used, the voltage can be detected more stably, and the inductance can be manufactured at low cost.

Example 4. In this embodiment, a circuit for outputting a signal when the collector-emitter voltage of the switching element 4 becomes 0 [V] is added to the magnetic detection means of the first embodiment. FIG. 5 is a circuit diagram showing the configuration of the high frequency heating apparatus of this embodiment, and FIG. 6 is a waveform diagram showing the waveform of the induced electromotive force generated in the collector-emitter voltage of the switching element 4 and the inductance 11. In FIG. 5, 1
Reference numeral 1 denotes an inductance, which is composed of the inductance element shown in Embodiments 2 and 3, or a spiral pattern formed on the substrate. A capacitor 17 and a diode 18 are connected in parallel to the inductance 11, one of which is connected to the base of a transistor 20 via a resistor 19 and the other is grounded. The collector of the transistor 20 is connected to the input terminal of the drive control circuit 8 and also connected to the DC power supply 22 via the resistor 21, and the emitter of the transistor 20 is grounded. Other configurations are similar to those of the first embodiment.

Next, the operation of this embodiment will be described. In this embodiment, as shown in the waveform diagram of FIG. 6A, the induced electromotive force generated in the collector-emitter voltage of the switching element 4 and the inductance 11 reaches 0 [V] at the same time. There is. Inductance 1
While the induced electromotive force is generated in No. 1, the transistor 20 is in the ON state, and the current from the DC power supply 22 is
The current flows from the collector to the emitter of the transistor 20 and does not flow to the drive control circuit 8. Therefore, the drive control circuit 8 does not turn on the switching element 4 because no signal is sent from the magnetic detection means 7.

When the induced electromotive force generated in the inductance 11 reaches 0 [V], the transistor 20 is turned off and the current from the DC power source 22 flows into the drive control circuit 8. Then, the drive control circuit 8 receives this current as a pulse signal for turning on the switching element 4, and turns on the switching element 4 after a certain period of time. In this embodiment, a signal is output by the circuit in the magnetic detection means 7 when the collector-emitter voltage of the switching element 4 becomes 0 [V].
It is not necessary to detect when the emitter-to-emitter voltage reaches 0 [V], and the drive control circuit 3 outputs the collector-emitter voltage of the switching element 4 at 0 [V] when a signal is input from the magnetic detection means 7. Since it is sufficient to control when it is determined that the drive control circuit 3 has reached, it is possible to simplify the drive control circuit 3.

Example 5. In this embodiment, by adjusting the constants of the inductance 11 and the capacitor 17 in the magnetic detecting means 7 of the fourth embodiment, as shown in (b) of FIG. ], The collector-emitter voltage of the switching element 4 reaches 0 [V] after a certain fixed time.

The operation of this embodiment is similar to that of the fourth embodiment. In this embodiment, the signal from the magnetic detection means 7 that informs the drive control circuit 8 that the collector-emitter voltage of the switching element 4 has reached 0 [V] is
As shown in (b) of FIG. 6, since the drive control circuit 8 has already been delayed for a certain time at the time of input to the drive control circuit 8, the drive control circuit 8 outputs from the magnetic detection means 7 as shown in the fourth embodiment. It is not necessary to perform the operation of turning on the switching element 4 after a certain period of time after receiving the signal No. 1, and only the operation of issuing a pulse voltage for turning on the switching element 4 at the same time when the signal is input from the magnetic detection means 7 is performed. You can do it like this. Therefore, the drive control circuit 8 does not need to include a delay circuit or the like for turning on the switching element 4 after a certain period of time after receiving the signal from the magnetic detection means 7, and the drive control circuit 8 is further simplified. It becomes possible to do.

Example 6. In this embodiment, the magnetic detecting means 7 of the first embodiment is composed of a Hall element. FIG. 7 is a circuit diagram showing the configuration of the high-frequency heating apparatus of this embodiment, and FIG.
FIG. 6 is an explanatory diagram for explaining a Hall effect. In FIG. 7, reference numeral 23 is a Hall element, and a DC current is supplied from the DC power supply 22 to the Hall element 23. The Hall element 23 has a leakage transformer 3 in a direction perpendicular to the current.
Is installed on the substrate so that the leakage magnetic flux of
Further, a detection signal output terminal is attached in the vertical direction for both the direct current and the leakage magnetic flux of the leakage transformer 3.

Next, the operation of this embodiment will be described. The Hall element 23 used in this embodiment is an element that produces the Hall effect. What is the Hall effect? As shown in Fig. 8, when a conductor or semiconductor in which an electric current flows is placed in a magnetic field having a direction component perpendicular to the electric current flow, the Hall effect can be obtained in both directions. This is a phenomenon in which a voltage is generated in the vertical direction. The magnitude of the Hall voltage generated by the Hall effect is proportional to the product of the current density and the magnetic flux density. Therefore, if a constant DC current is always applied, the magnitude of the Hall voltage changes due to the change of the leakage magnetic flux of the leakage transformer 8. In this embodiment, by inputting the Hall voltage to the drive control circuit 8, the drive control circuit 8 can detect the timing when the collector-emitter voltage of the switching element 4 becomes 0 [V].

In this embodiment, as in the second embodiment, the collector-emitter voltage of the switching element 4 is indirectly detected by the leakage magnetic flux of the leakage transformer 3.
An optimum signal level to be processed by the drive circuit 8 is obtained as a voltage detection signal, and an element for lowering the voltage as in the case of directly detecting the voltage from the collector of the switching element 4 is not necessary, and heat generation is eliminated. The number of parts can be reduced, and the loss can be reduced.

Example 7. In this embodiment, the magnetic detection means 7 of the first embodiment is composed of a magnetoresistive element. Figure 9
FIG. 3 is a circuit diagram showing the configuration of the high-frequency heating device of this embodiment. In the figure, reference numeral 24 denotes a magnetoresistive element, one of which is connected to the drive control circuit 8 and also connected to the DC power source 22 through the resistor 25, and the other is grounded.

Next, the operation of this embodiment will be described. The magnetoresistive element 24 used in this embodiment is an element having a magnetoresistive effect in which the resistivity changes by the passage of a magnetic field. This magnetoresistive element 24 is installed near the leakage transformer 3 and a DC voltage is applied. Leakage transformer 3
The resistance value of the magnetoresistive element 24 changes due to the change of the leakage magnetic flux, and the voltage applied across the magnetoresistive element 24 changes accordingly. In this embodiment, by inputting the voltage applied across the magnetoresistive element 24 to the drive control circuit 8, the drive control circuit 8 sets the timing at which the collector-emitter voltage of the switching element 4 becomes 0 [V]. Can be detected.

In this embodiment, as in the second embodiment, the collector-emitter voltage of the switching element 4 is indirectly detected by the leakage magnetic flux of the leakage transformer 3.
An optimum signal level to be processed by the drive control circuit 8 is obtained as a voltage detection signal, and there is no need for an element for reducing the voltage as in the case of directly detecting the voltage from the collector of the switching element 4, The number of heat generating parts can be reduced,
It is possible to reduce the loss.

Example 8. In this embodiment, the magnetic detecting means 7 of the first embodiment is constructed by a Wheatstone bridge having a magnetoresistive element on one side. FIG. 10 is a circuit diagram showing the configuration of the high-frequency heating device of this embodiment. In the figure, 25, 26 and 27 are resistors, and the magnetoresistive element 24
And resistors 25, 26 and 27 form a Wheatstone bridge.

Next, the operation of this embodiment will be described. First, the magnetoresistive element 24 is installed in the vicinity of the leakage transformer 3 as in the seventh embodiment, and a DC voltage is applied. Then, due to the resistance change of the magnetoresistive element due to the leakage magnetic flux of the leakage transformer 3, the potential difference between the terminals serving as the output terminal to the drive control circuit 8 changes. In this embodiment, the drive control circuit 8 can detect the timing when the collector-emitter voltage of the switching element 4 becomes 0 [V] by inputting the potential difference of the output terminal of the Wheatstone bridge to the drive control circuit 8. .

In this embodiment, as in the second embodiment, the collector-emitter voltage of the switching element 4 is indirectly detected by the leakage magnetic flux of the leakage transformer 3.
An optimum signal level to be processed by the drive control circuit 8 is obtained as a voltage detection signal, and there is no need for an element for reducing the voltage as in the case of directly detecting the voltage from the collector of the switching element 4, The number of heat generating parts can be reduced,
It is possible to reduce the loss.

Example 9. In this embodiment, the power source of the drive control circuit 8 of the first embodiment is supplied from the power source of the operation control board of the high frequency heating device. FIG. 11 is a circuit diagram showing the configuration of the high-frequency heating device of this embodiment. In the figure, 29 is an insulating circuit for insulating the switching element 4 from the drive control circuit 8 because the drive control circuit 8 has a different power supply, and 30 is a power supply for the operation control board of the high-frequency heating device.

In the first embodiment, the drive control circuit 8 is supplied with power from the commercial AC power supply 1 or the rectifying / smoothing circuit 2.
Needless to say, as shown in FIG. 11, even if the drive control circuit 8 is powered from the power source 30 of the operation control board, the same operation as in the first embodiment can be achieved. In this embodiment, the power source of the drive control circuit 8 is supplied from the power source 30 of the operation control board. Therefore, when the power source is supplied from the commercial AC power source 1 or the rectifying / smoothing circuit 2, it is necessary to reduce the voltage. No pressure element is required, the number of heat-generating components is further reduced, and the loss can be further reduced.

Example 10. In this embodiment, the function of receiving the signal from the magnetic detection means 7 and controlling the driving of the switching element 4 is included in the microcomputer on the operation control board of the high-frequency heating device. FIG. 12 is a circuit diagram showing the configuration of the high-frequency heating device of this embodiment.
In the figure, 31 is a microcomputer, and the microcomputer 31 sends a drive signal for driving the switching element 4 to a drive circuit 32 by a signal from the magnetic detection means 7. In this case, since the microcomputer 31 drives and controls the switching element 4, more precise and fine control can be performed, and the circuit configuration can be simplified.

[0045]

As described above, according to the first invention, the magnetic flux detecting means arranged near the transformer or the inductor detects the leakage magnetic flux from the transformer or the inductor.
Since the detection signal corresponding to the applied voltage of the switching element is output and the drive control means drives the switching element based on the detection signal from the magnetic detection means, the applied voltage of the switching element is indirectly detected. You can
Moreover, since it is possible to detect at a signal level that is optimal for input to the drive control means, it is possible to reduce the number of heat-generating components for dividing the voltage and reduce the loss.

According to the second invention, the magnetic flux detecting means arranged near the transformer or the inductor detects the leakage magnetic flux from the transformer or the inductor, and when the voltage applied to the switching element becomes zero. The detection signal is output, and the drive control means drives the switching element based on the detection signal from the magnetic detection means. Therefore, the voltage applied to the switching element can be indirectly detected, and the drive control means Since it is possible to detect at the optimum signal level for inputting, it is possible to reduce the number of heat-generating components for dividing the voltage, reduce loss, and further, the drive control means makes the voltage applied to the switching element zero. There is no need to judge when the situation occurs, and there is an effect that a simplified configuration can be achieved.

According to the third aspect of the invention, the magnetic flux detecting means arranged near the transformer or the inductor detects the leakage magnetic flux from the transformer or the inductor, which corresponds to the voltage applied to the switching element and which has a predetermined value. Since the detection signal delayed in time is output and the drive control means drives the switching element based on the detection signal from the magnetic detection means, the drive control means does not need to delay the detection signal. This has the effect that the configuration can be simplified.

According to the fourth invention, the magnetic flux detecting means arranged near the transformer or the inductor detects the leakage magnetic flux from the transformer or the inductor, and the applied voltage to the switching element becomes zero. After the lapse of time, the detection signal is output, and the drive control means drives the switching element based on the detection signal from the magnetic detection means. Is unnecessary and the detection signal does not need to be delayed, which has the effect of further simplifying the configuration.

According to the fifth invention, the drive control means is supplied with power from the cooking control board for controlling the cooking device. Therefore, in order to supply power to the drive control means,
There is an effect that an element for lowering the voltage becomes unnecessary, the number of heat generating parts is further reduced, and the loss can be further reduced. According to the sixth aspect of the invention, since the magnetic detecting means has the spiral pattern wiring formed on the substrate, the magnetic flux leakage can be detected more stably, and the magnetic detecting means can be manufactured at low cost. It has the effect that it can be configured.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a high-frequency heating device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a high frequency heating device according to a second embodiment.

FIG. 3 is a schematic diagram when an inductance element is used for the inductance.

FIG. 4 is an explanatory diagram for explaining a spiral pattern wiring printed on a circuit board.

FIG. 5 is a circuit diagram showing a configuration of a high frequency heating device according to a fourth embodiment.

6 is a waveform diagram showing a waveform of a collector-emitter voltage of the switching element 4 and a waveform of an induced electromotive force generated in the inductance 11. FIG.

FIG. 7 is a circuit diagram showing a configuration of a high frequency heating apparatus of Example 6.

FIG. 8 is an explanatory diagram for explaining a Hall effect.

FIG. 9 is a circuit diagram showing a configuration of a high frequency heating apparatus of Example 7.

FIG. 10 is a circuit diagram showing a configuration of a high frequency heating apparatus of Example 8.

FIG. 11 is a circuit diagram showing a configuration of a high frequency heating apparatus of Example 9.

FIG. 12 is a circuit diagram showing a configuration of a high frequency heating apparatus of Example 10.

FIG. 13 is a circuit diagram showing a configuration of a conventional heating cooker.

[Explanation of symbols]

1 commercial AC power supply, 2 rectification smoothing circuit, 3 leakage transformer (transformer), 4 switching element, 7 magnetic detection means, 8 drive control circuit, 10 magnetron, 13 circuit board, 14 spiral-shaped formed on the board Pattern wiring, 16 circuit patterns, 200 inductors for resonance.

[Procedure amendment]

[Submission date] November 29, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title of invention Heating cooker

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating cooker, and more particularly to a control for maintaining safety and stability of a switching element for generating a high frequency power source and operating it stably.

[0002]

2. Description of the Related Art FIG. 13 shows, for example, Japanese Examined Patent Publication No. 60-1458.
It is a circuit diagram which shows the structure of the conventional heating cooker shown by the 5th publication, and this shows the induction heating cooker. This heating cooker includes a rectifying / smoothing circuit 2 for rectifying and smoothing a commercial AC power supply 1, a switching element 4, a diode 5,
The resonance capacitor 6, the induction heating coil 200, and the drive control circuit 201 are provided. Next, the operation of the conventional heating cooker will be described. First, the commercial AC power supply 1 is rectified by the rectifying / smoothing circuit 2, and the smoothed DC is turned on / off by the switching element 4 which is drive-controlled by the drive control circuit 201, whereby the resonance capacitor 6 and the induction heating coil 2 are turned on.
00 forms a parallel resonant circuit, and an alternating current having the resonant frequency flows through the induction heating coil 200. Due to the electromagnetic induction effect of this alternating current, an eddy current flows in the cooking pan via the insulating plate. The cooking pot is heated by this eddy current and the electric resistance of the cooking pot itself.

In this conventional example, the drive control circuit 201
Detects a voltage corresponding to the voltage generated between the collector and the emitter of the switching element 4. This is because the drive control circuit 201 switches the switching element 4 before the collector-emitter voltage of the switching element 4 reaches 0 [V].
When the switching element 4 is turned on by driving, the switching element 4 causes a loss in the period from when the switching element 4 is turned on until the collector-emitter voltage becomes 0 [V]. The control circuit 201 detects the collector-emitter voltage of the switching element 4,
This is because the switching element 4 is driven within a certain period of time after detecting that the voltage has reached 0 [V].

Further, the high-frequency heating device uses the same voltage resonance circuit as the induction heating cooker, and among the above-mentioned operations,
Instead of the induction heating coil 200, the primary side of the leakage transformer forms a parallel resonance circuit, and the same operation as the induction heating cooker is performed except that an AC current flows and the secondary side is rectified to drive the magnetron. Further, also in the portion that detects the voltage across the induction heating coil 200, the conventional high-frequency heating device directly detects the collector-emitter voltage of the switching element 4 by the voltage detection means, and the switching element 4
The detection signal is sent to the drive control circuit for driving the switching element 4 and the drive control circuit drives the switching element 4 at the optimum timing. Is the same.

[0005]

As described above, in the conventional heating device, in order to reduce the switching loss of the switching element, after the collector-emitter voltage of the switching element reaches 0 [V], A high frequency pulse voltage for turning on the switching element is applied to the gate of the switching element. At this time, since the collector-emitter voltage of the switching element was directly detected from the collector terminal, the detection voltage was too high, and a voltage dividing element for detecting the voltage was required. The element becomes a heat-generating component, and the power source of the drive control circuit that drives the switching element to generate a high-frequency pulse voltage uses a rectified commercial AC power source or DC from a rectifying / smoothing circuit. Also, an element for dividing the voltage is required, and these elements are heat generating parts. Then, there is a problem that the loss of the heating cooker becomes large due to these heat-generating components.

When the power source of the drive control circuit for driving the switching element is supplied from the operation control board power source transformer of the heating cooker to reduce the number of heat-generating components, the drive control circuit and the switching element are grounded differently. Therefore, in the case of directly detecting the collector voltage of the switching element, it is necessary to provide an insulating means at the interface between the two. Depending on the insulating means used, the voltage corresponding to the detected collector-emitter voltage causes a delay with respect to the actual collector-emitter voltage, and the degree of the delay cannot be controlled. However, there is a problem that the switching element cannot be controlled accurately because of the variation.

The present invention has been made to solve the above problems, and a magnetic detection means is used as a collector-emitter voltage detection means of a switching element to detect the collector-emitter voltage of the switching element. By indirectly detecting the detection voltage corresponding to, the detection voltage of the optimum voltage can be obtained when processing the detection signal, and the stable operation of the high frequency heating device can be obtained, and the number of heat-generating components can be reduced. The purpose is to reduce the loss due to.

[0008]

A heating cooker according to a first aspect of the present invention comprises a rectifying / smoothing circuit for rectifying and smoothing a commercial AC power source,
A resonance circuit having a transformer and a resonance capacitor, or an induction heating coil and a resonance capacitor, one end of which is connected to one end of the output side of the rectifying and smoothing circuit, and the other end of the resonance circuit and the other end of the output side of the rectifying and smoothing circuit. And a switching element for supplying high-frequency power to the magnetron via a transformer or for supplying high-frequency power to an induction heating coil, and a transformer or induction heating. Located in the vicinity of the coil, detects the leakage magnetic flux from the transformer or the induction heating coil, based on the detection signal from the magnetic detection means, which outputs a detection signal corresponding to the applied voltage of the switching element, the magnetic detection means, And a drive control means for driving the switching element.

A cooking device according to a second aspect of the present invention comprises a rectifying / smoothing circuit for rectifying and smoothing a commercial AC power source, a transformer and a resonant capacitor, or an induction heating coil and a resonant capacitor, one end of which is the output side of the rectifying / smoothing circuit. Is connected between one end of the resonance circuit and the other end of the resonance circuit and the other end of the output side of the rectifying and smoothing circuit, and causes the resonance circuit to resonate by the on / off operation, and the magnetron through the transformer. And a switching element that supplies high-frequency power to the induction heating coil or a high-frequency power to the induction heating coil, and is arranged in the vicinity of the transformer or the induction heating coil, detects the leakage magnetic flux from the transformer or the induction heating coil, and Magnetic detection means for outputting a detection signal when the applied voltage becomes zero, and drive control means for driving the switching element based on the detection signal from the magnetic detection means. It is those with a.

A heating cooker according to a third aspect of the present invention comprises a rectifying / smoothing circuit for rectifying and smoothing a commercial AC power source, a transformer and a resonance capacitor, or an induction heating coil and a resonance capacitor, one end of which is the output side of the rectification and smoothing circuit. Is connected between one end of the resonance circuit and the other end of the resonance circuit and the other end of the output side of the rectifying and smoothing circuit, and causes the resonance circuit to resonate by the on / off operation, and the magnetron through the transformer. And a switching element that supplies high-frequency power to the induction heating coil or a high-frequency power to the induction heating coil, and is arranged in the vicinity of the transformer or the induction heating coil, detects the leakage magnetic flux from the transformer or the induction heating coil, and A magnetic detection unit that outputs a detection signal corresponding to an applied voltage and delayed by a predetermined time, and a switching element is driven based on the detection signal from the magnetic detection unit. In which and a dynamic control unit.

A heating cooker according to a fourth aspect comprises a rectifying / smoothing circuit for rectifying and smoothing a commercial AC power source, a transformer and a resonance capacitor, or an induction heating coil and a resonance capacitor, and one end of which is an output side of the rectification / smoothing circuit. Is connected between one end of the resonance circuit and the other end of the resonance circuit and the other end of the output side of the rectifying and smoothing circuit, and causes the resonance circuit to resonate by the on / off operation, and the magnetron through the transformer. And a switching element that supplies high-frequency power to the induction heating coil or a high-frequency power to the induction heating coil, and is arranged in the vicinity of the transformer or the induction heating coil, detects the leakage magnetic flux from the transformer or the induction heating coil, and The applied voltage becomes zero,
Magnetic detection means for outputting a detection signal after a predetermined time has passed,
Drive control means for driving the switching element based on a detection signal from the magnetic detection means.

In the heating cooker according to the fifth aspect of the present invention, the drive control means is further supplied with power from a cooking control board for controlling the cooker. In the heating cooker according to the sixth aspect of the invention, the magnetism detecting means has a spiral pattern wiring formed on the substrate.

[0013]

In the first aspect of the invention, the rectifying and smoothing circuit is used.
The commercial AC power supply is rectified and smoothed, and one end is connected to the output side end of the rectification smoothing circuit and the other side of the output side of the rectification smoothing circuit is connected to the switching element to turn it on.・ Resonance circuit resonates due to OFF operation, high frequency power is supplied to the magnetron through the transformer, or high frequency power is supplied to the induction heating coil, and magnetic detection means arranged near the transformer or induction heating coil , The leakage flux from the transformer or the induction heating coil is detected, a detection signal corresponding to the voltage applied to the switching element is output, and the drive control means drives the switching element based on the detection signal from the magnetic detection means. It

In the second aspect of the invention, the commercial AC power supply is rectified and smoothed by the rectifying and smoothing circuit, and one end of the resonance circuit connected to one end on the output side of the rectifying and smoothing circuit and the output side of the rectifying and smoothing circuit. The switching element connected to the other end causes the resonance circuit to resonate due to its on / off operation, and high frequency power is supplied to the magnetron via the transformer or high frequency power is supplied to the induction heating coil. Magnetic flux is detected from the transformer or the induction heating coil by the magnetic detection means arranged in the vicinity of the transformer or the induction heating coil, and a detection signal is output when the voltage applied to the switching element becomes zero, and drive control is performed. The means drives the switching element based on the detection signal from the magnetic detection means.

In the third aspect of the invention, the commercial AC power supply is rectified and smoothed by the rectifying and smoothing circuit, and one end of the resonance circuit connected to one end of the output side of the rectifying and smoothing circuit and the output side of the rectifying and smoothing circuit. The switching element connected to the other end causes the resonance circuit to resonate due to its on / off operation, and high frequency power is supplied to the magnetron via the transformer or high frequency power is supplied to the induction heating coil. The magnetic flux detected from the transformer or the induction heating coil by the magnetic detection means arranged in the vicinity of the transformer or the induction heating coil, corresponding to the applied voltage of the switching element, and
A detection signal delayed by a predetermined time is output, and the drive control unit drives the switching element based on the detection signal from the magnetic detection unit.

In the fourth invention, the commercial AC power source is rectified and smoothed by the rectifying / smoothing circuit, and one end of the resonance circuit connected to one end on the output side of the rectifying / smoothing circuit and the output side of the rectifying / smoothing circuit. The switching element connected to the other end causes the resonance circuit to resonate due to its on / off operation, and high frequency power is supplied to the magnetron via the transformer or high frequency power is supplied to the induction heating coil. The magnetic flux detected from the transformer or the induction heating coil is detected by the magnetic detection means arranged in the vicinity of the container or the induction heating coil, the applied voltage of the switching element becomes zero, and the detection signal is output after a predetermined time has passed, The drive control means drives the switching element based on the detection signal from the magnetic detection means.

In the fifth invention, the drive control means is
Power is supplied from the cooking control board that controls the cooking device. In the sixth invention, the magnetic detection means has a spiral pattern wiring formed on the substrate.

[0018]

EXAMPLES Example 1. FIG. 1 is a circuit diagram showing the configuration of a high frequency heating apparatus according to an embodiment of the present invention. In the figure, 1 is a commercial AC power supply, 2 is a rectifying / smoothing circuit for rectifying and smoothing AC from the commercial AC power supply, 3 is a leakage transformer connected to the output side of the rectifying / smoothing circuit 2, and 4 is a leakage transformer 3. A switching element connected in series to the secondary side, 5 a diode connected in anti-parallel to the switching element 4, 6 a resonant capacitor connected in parallel to the primary side of the leakage transformer 3, and 7 a leakage transformer 3
In the vicinity of, the magnetic detection means provided at a location where the time when the collector-emitter voltage of the switching element 4 reaches 0 [V] can be accurately detected, and 8 is a switching element based on the detection signal from the magnetic detection means 7. 4 is a drive control circuit for driving the power source 4, and its power source is supplied from the commercial AC power source 1 or the rectifying / smoothing circuit 2. Reference numeral 9 is a voltage doubler rectifier circuit connected to the secondary side of the leakage transformer 3, and 10 is a magnetron connected to the output side of the voltage doubler rectifier circuit 9.

Next, the operation of this embodiment will be described. First, the rectifying / smoothing circuit 2 rectifies and smoothes the AC of the commercial AC power supply 1 and outputs a DC power supply, and this DC power supply is input to the primary side of the leakage transformer 3. In addition, 1 of the leakage transformer 3
The switching element 4 is connected in series to the circuit on the next side,
The resonance capacitor 6 is connected in parallel, a high-frequency pulse signal is sent from the drive control circuit 8 to the base of the switching element 4, the switching element 4 is turned on / off at the high frequency, and the capacitance of the resonance capacitor 6 is increased. A parallel resonance circuit is formed by the inductance of the primary side of the leakage transformer 3, and the AC power supply of the resonance frequency is applied to the primary side of the leakage transformer 3.

In response to this, a high voltage is generated on the secondary side of the leakage transformer 3, the high voltage is input to the voltage doubler rectifier circuit 9, and the voltage doubler rectifier circuit 9 further boosts it. , And rectify and send to the magnetron 10. Then, the magnetron 10 receives the high voltage applied from the voltage doubler rectifier circuit 9,
The filament of the magnetron 10 is oscillated by a high-frequency power source supplied from the tertiary winding of the leakage transformer 3, and outputs microwaves to heat the food to be cooked or the like.

Further, the magnetic detection means 7 detects a voltage corresponding to the collector-emitter voltage of the switching element 4 by the leakage magnetic flux of the leakage transformer 3 and issues a detection signal. The drive control circuit 8 detects the timing at which the collector-emitter voltage of the switching element 4 becomes 0 [V] based on the signal, and outputs to the switching element 4 a high-frequency pulse signal that turns on at a timing at which no loss occurs in the switching element 4. to be sending.

In this embodiment, the collector-emitter voltage of the switching element 4 is indirectly detected by the leakage magnetic flux of the leakage transformer 3, so that it is processed by the drive control circuit 8 as a voltage detection signal. An optimum signal level can be obtained, and an element for lowering the voltage as in the case of directly detecting the voltage from the collector of the switching element 4 is not required, so that heat-generating components can be reduced and loss can be reduced. Becomes

Embodiment 2 FIG. In this embodiment, the magnetic detection means 7 of the first embodiment is composed of an inductance. FIG. 2 is a circuit diagram showing the configuration of the high frequency heating apparatus of this embodiment,
FIG. 3 is a schematic diagram when an inductance element is used for the inductance. In FIG. 2, reference numeral 11 is an inductance, and the other configurations are similar to those of the first embodiment. 3, 12 is an inductance element which is an example of the inductance 11 of FIG. 2, 13 is a circuit board of a high frequency heating device, and the inductance element 12 is a circuit board 13 near the leakage transformer 3 as shown in FIG. Is installed in the vehicle and the leakage magnetic flux of the leakage transformer 3 is detected.

Next, the operation of this embodiment will be described. First, the inductance 11 detects the voltage corresponding to the collector-emitter voltage of the switching element 4 by the induced electromotive force generated in the inductance 11 by the leakage magnetic flux of the leakage transformer 3. And the inductance 1
1 transmits the generated induced electromotive force corresponding to the collector-emitter voltage of the switching element 4 to the drive control circuit 8,
The drive control circuit 8 detects a timing at which the collector-emitter voltage of the switching element 4 becomes 0 [V], and outputs a high-frequency pulse signal for turning on the switching element 4 at a timing at which no loss occurs in the switching element 4. It is designed to send the switching element 4.

In this embodiment, since the collector-emitter voltage of the switching element 4 is indirectly detected by the leakage magnetic flux of the leakage transformer 3, it can be processed by the drive circuit 8 as a voltage detection signal. An optimum signal level can be obtained, an element for reducing the voltage as in the case of directly detecting the voltage from the collector of the switching element 4 is not necessary, heat-generating parts can be reduced, and loss can be reduced. Become.

Example 3. In this embodiment, the magnetic detecting means 7 of the first embodiment is constituted by a spiral pattern wiring printed on a circuit board. FIG. 4 is an explanatory diagram for explaining the spiral pattern wiring printed on the circuit board. In the figure, 14 is a spiral pattern wiring printed on the substrate, 15 is a conducting wire passing through the back side of the circuit board 13, and 16 is a circuit pattern.

Next, the operation of this embodiment will be described. The wiring of the spiral pattern 14 of this embodiment is formed in the vicinity of the leakage transformer 3, and an induced electromotive force is generated in the pattern 14 by the leakage magnetic flux of the leakage transformer 3, and the induced electromotive force causes a switching element. The voltage corresponding to the collector-emitter voltage of 4 is detected.
In this embodiment, since the inductance printed on the circuit board 13 is used, the voltage can be detected more stably, and the inductance can be manufactured at low cost.

Example 4. In this embodiment, a circuit for outputting a signal when the collector-emitter voltage of the switching element 4 becomes 0 [V] is added to the magnetic detection means of the first embodiment. FIG. 5 is a circuit diagram showing the configuration of the high frequency heating apparatus of this embodiment, and FIG. 6 is generated in the collector-emitter voltage of the switching element 4 and the inductance 11.
5 is a waveform diagram showing a waveform of an induced electromotive force corresponding to a collector-emitter voltage of the switching element 4. FIG. In FIG. 5, reference numeral 11 is an inductance, and is the second and third embodiments.
The inductance element shown in or the spiral pattern formed on the substrate. Also,
A capacitor 17 and a diode 18 are connected in parallel to the inductance 11, one of which is connected to the base of a transistor 20 via a resistor 19 and the other is grounded. The collector of the transistor 20 is connected to the input terminal of the drive control circuit 8 and also connected to the DC power supply 22 via the resistor 21, and the emitter of the transistor 20 is grounded. Other configurations are similar to those of the first embodiment.

Next, the operation of this embodiment will be described. In this embodiment, as shown in the waveform diagram of FIG. 6A, the switching element 4 is generated in the collector-emitter voltage of the switching element 4 and the inductance 11.
The induced electromotive force corresponding to the collector-emitter voltage of is
At the same time, it reaches 0 [V]. The transistor 20 is in the ON state while the induced electromotive force corresponding to the collector-emitter voltage of the switching element 4 is generated in the inductance 11, and the current from the DC power supply 22 flows from the collector to the emitter of the transistor 20. And does not flow to the drive control circuit 8. Therefore, the drive control circuit 8 does not turn on the switching element 4 because no signal is sent from the magnetic detection means 7.

When the induced electromotive force generated in the inductance 11 reaches 0 [V], the transistor 20 is turned off and the current from the DC power source 22 flows into the drive control circuit 8. Then, the drive control circuit 8 receives this current as a pulse signal for turning on the switching element 4, and turns on the switching element 4 after a certain period of time. In this embodiment, a signal is output by the circuit in the magnetic detection means 7 when the collector-emitter voltage of the switching element 4 becomes 0 [V].
It is not necessary to detect when the emitter-to-emitter voltage reaches 0 [V], and the drive control circuit 3 outputs the collector-emitter voltage of the switching element 4 at 0 [V] when a signal is input from the magnetic detection means 7. Since it is sufficient to control when it is determined that the drive control circuit 3 has reached, it is possible to simplify the drive control circuit 3.

Example 5. In this embodiment, by adjusting the constants of the inductance 11 and the capacitor 17 in the magnetic detecting means 7 of the fourth embodiment, as shown in (b) of FIG. ], The collector-emitter voltage of the switching element 4 reaches 0 [V] after a certain fixed time.

The operation of this embodiment is similar to that of the fourth embodiment. In this embodiment, the signal from the magnetic detection means 7 that informs the drive control circuit 8 that the collector-emitter voltage of the switching element 4 has reached 0 [V] is
As shown in (b) of FIG. 6, since the drive control circuit 8 has already been delayed for a certain time at the time of input to the drive control circuit 8, the drive control circuit 8 outputs from the magnetic detection means 7 as shown in the fourth embodiment. It is not necessary to perform the operation of turning on the switching element 4 after a certain period of time after receiving the signal No. 1, and only the operation of issuing a pulse voltage for turning on the switching element 4 at the same time when the signal is input from the magnetic detection means 7 is performed. You can do it like this. Therefore, the drive control circuit 8 does not need to include a delay circuit or the like for turning on the switching element 4 after a certain period of time after receiving the signal from the magnetic detection means 7, and the drive control circuit 8 is further simplified. It becomes possible to do.

Example 6. In this embodiment, the magnetic detecting means 7 of the first embodiment is composed of a Hall element. FIG. 7 is a circuit diagram showing the configuration of the high-frequency heating apparatus of this embodiment, and FIG.
FIG. 6 is an explanatory diagram for explaining a Hall effect. In FIG. 7, reference numeral 23 is a Hall element, and a DC current is supplied from the DC power supply 22 to the Hall element 23. The Hall element 23 has a leakage transformer 3 in a direction perpendicular to the current.
Is installed on the substrate so that the leakage magnetic flux of
Further, a detection signal output terminal is attached in the vertical direction for both the direct current and the leakage magnetic flux of the leakage transformer 3.

Next, the operation of this embodiment will be described. The Hall element 23 used in this embodiment is an element that produces the Hall effect. What is the Hall effect? As shown in Fig. 8, when a conductor or semiconductor in which an electric current flows is placed in a magnetic field having a direction component perpendicular to the electric current flow, the Hall effect can be obtained in both directions. This is a phenomenon in which a voltage is generated in the vertical direction. The magnitude of the Hall voltage generated by the Hall effect is proportional to the product of the current density and the magnetic flux density. Therefore, if a constant DC current is always applied, the magnitude of the Hall voltage changes due to the change of the leakage magnetic flux of the leakage transformer 8. In this embodiment, by inputting the Hall voltage to the drive control circuit 8, the drive control circuit 8 can detect the timing when the collector-emitter voltage of the switching element 4 becomes 0 [V].

In this embodiment, as in the second embodiment, the collector-emitter voltage of the switching element 4 is indirectly detected by the leakage magnetic flux of the leakage transformer 3.
An optimum signal level to be processed by the drive circuit 8 is obtained as a voltage detection signal, and an element for lowering the voltage as in the case of directly detecting the voltage from the collector of the switching element 4 is not necessary, and heat generation is eliminated. The number of parts can be reduced, and the loss can be reduced.

Example 7. In this embodiment, the magnetic detection means 7 of the first embodiment is composed of a magnetoresistive element. Figure 9
FIG. 3 is a circuit diagram showing the configuration of the high-frequency heating device of this embodiment. In the figure, reference numeral 24 denotes a magnetoresistive element, one of which is connected to the drive control circuit 8 and also connected to the DC power source 22 through the resistor 25, and the other is grounded.

Next, the operation of this embodiment will be described. The magnetoresistive element 24 used in this embodiment is an element having a magnetoresistive effect in which the resistivity changes by the passage of a magnetic field. This magnetoresistive element 24 is installed near the leakage transformer 3 and a DC voltage is applied. Leakage transformer 3
The resistance value of the magnetoresistive element 24 changes due to the change of the leakage magnetic flux, and the voltage applied across the magnetoresistive element 24 changes accordingly. In this embodiment, by inputting the voltage applied across the magnetoresistive element 24 to the drive control circuit 8, the drive control circuit 8 sets the timing at which the collector-emitter voltage of the switching element 4 becomes 0 [V]. Can be detected.

In this embodiment, as in the second embodiment, the collector-emitter voltage of the switching element 4 is indirectly detected by the leakage magnetic flux of the leakage transformer 3.
An optimum signal level to be processed by the drive control circuit 8 is obtained as a voltage detection signal, and there is no need for an element for reducing the voltage as in the case of directly detecting the voltage from the collector of the switching element 4, The number of heat generating parts can be reduced,
It is possible to reduce the loss.

Example 8. In this embodiment, the magnetic detecting means 7 of the first embodiment is constructed by a Wheatstone bridge having a magnetoresistive element on one side. FIG. 10 is a circuit diagram showing the configuration of the high-frequency heating device of this embodiment. In the figure, 25, 26 and 27 are resistors, and the magnetoresistive element 24
And resistors 25, 26 and 27 form a Wheatstone bridge.

Next, the operation of this embodiment will be described. First, the magnetoresistive element 24 is installed in the vicinity of the leakage transformer 3 as in the seventh embodiment, and a DC voltage is applied. Then, due to the resistance change of the magnetoresistive element due to the leakage magnetic flux of the leakage transformer 3, the potential difference between the terminals serving as the output terminal to the drive control circuit 8 changes. In this embodiment, the drive control circuit 8 can detect the timing when the collector-emitter voltage of the switching element 4 becomes 0 [V] by inputting the potential difference of the output terminal of the Wheatstone bridge to the drive control circuit 8. .

In this embodiment, as in the second embodiment, the collector-emitter voltage of the switching element 4 is indirectly detected by the leakage magnetic flux of the leakage transformer 3.
An optimum signal level to be processed by the drive control circuit 8 is obtained as a voltage detection signal, and there is no need for an element for reducing the voltage as in the case of directly detecting the voltage from the collector of the switching element 4, The number of heat generating parts can be reduced,
It is possible to reduce the loss.

Example 9. In this embodiment, the power source of the drive control circuit 8 of the first embodiment is supplied from the power source of the operation control board of the high frequency heating device. FIG. 11 is a circuit diagram showing the configuration of the high-frequency heating device of this embodiment. In the figure, 29 is an insulating circuit for insulating the switching element 4 from the drive control circuit 8 because the drive control circuit 8 has a different power supply, and 30 is a power supply for the operation control board of the high-frequency heating device.

In the first embodiment, the drive control circuit 8 is supplied with power from the commercial AC power supply 1 or the rectifying / smoothing circuit 2.
Needless to say, as shown in FIG. 11, even if the drive control circuit 8 is powered from the power source 30 of the operation control board, the same operation as in the first embodiment can be achieved. In this embodiment, the power source of the drive control circuit 8 is supplied from the power source 30 of the operation control board. Therefore, when the power source is supplied from the commercial AC power source 1 or the rectifying / smoothing circuit 2, it is necessary to reduce the voltage. No pressure element is required, the number of heat-generating components is further reduced, and the loss can be further reduced.

Example 10. In this embodiment, the function of receiving the signal from the magnetic detection means 7 and controlling the driving of the switching element 4 is included in the microcomputer on the operation control board of the high-frequency heating device. FIG. 12 is a circuit diagram showing the configuration of the high-frequency heating device of this embodiment.
In the figure, 31 is a microcomputer, and the microcomputer 31 sends a drive signal for driving the switching element 4 to a drive circuit 32 by a signal from the magnetic detection means 7. In this case, since the microcomputer 31 drives and controls the switching element 4, more precise and fine control can be performed, and the circuit configuration can be simplified.

[0045]

As described above, according to the first aspect of the invention, the magnetic flux detecting means arranged in the vicinity of the transformer or the induction heating coil detects the leakage magnetic flux from the transformer or the induction heating coil to perform switching. Since the detection signal corresponding to the applied voltage of the element is output and the drive control means drives the switching element based on the detection signal from the magnetic detection means, the applied voltage of the switching element can be indirectly detected. Moreover, since it is possible to detect at a signal level optimum for input to the drive control means, it is possible to reduce the number of heat-generating components for dividing the voltage and reduce the loss.

According to the second aspect of the invention, the magnetic flux detecting means arranged near the transformer or the induction heating coil detects the leakage magnetic flux from the transformer or the induction heating coil, and the applied voltage to the switching element becomes zero. When this happens, a detection signal is output, and the drive control means drives the switching element based on the detection signal from the magnetic detection means, so the voltage applied to the switching element can be indirectly detected.
Moreover, since it is possible to detect at a signal level that is optimal for input to the drive control means, it is possible to reduce the number of heat-generating components for dividing the voltage, and it is possible to reduce losses. There is no need to judge when the applied voltage becomes zero, and the configuration can be simplified.

According to the third aspect of the invention, the magnetic flux detecting means arranged near the transformer or the induction heating coil detects the leakage magnetic flux from the transformer or the induction heating coil and responds to the voltage applied to the switching element. Further, since the detection signal delayed by a predetermined time is output and the drive control means drives the switching element based on the detection signal from the magnetic detection means, the drive control means needs to delay the detection signal. Since it is eliminated, there is an effect that a simplified structure can be obtained.

According to the fourth aspect of the invention, the magnetic flux detecting means arranged in the vicinity of the transformer or the induction heating coil detects the leakage magnetic flux from the transformer or the induction heating coil, and the applied voltage to the switching element becomes zero. Then, after a lapse of a predetermined time, the detection signal is output, and the drive control means drives the switching element based on the detection signal from the magnetic detection means. Since it is not necessary to judge when the time becomes, and it is not necessary to delay the detection signal, there is an effect that the configuration can be further simplified.

According to the fifth invention, the drive control means is supplied with power from the cooking control board for controlling the cooking device. Therefore, in order to supply power to the drive control means,
There is an effect that an element for lowering the voltage becomes unnecessary, the number of heat generating parts is further reduced, and the loss can be further reduced. According to the sixth aspect of the invention, since the magnetic detecting means has the spiral pattern wiring formed on the substrate, the magnetic flux leakage can be detected more stably, and the magnetic detecting means can be manufactured at low cost. It has the effect that it can be configured.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a high-frequency heating device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a high frequency heating device according to a second embodiment.

FIG. 3 is a schematic diagram when an inductance element is used for the inductance.

FIG. 4 is an explanatory diagram for explaining a spiral pattern wiring printed on a circuit board.

FIG. 5 is a circuit diagram showing a configuration of a high frequency heating device according to a fourth embodiment.

6 is a waveform diagram showing a waveform of a collector-emitter voltage of the switching element 4 and a waveform of an induced electromotive force generated in the inductance 11. FIG.

FIG. 7 is a circuit diagram showing a configuration of a high frequency heating apparatus of Example 6.

FIG. 8 is an explanatory diagram for explaining a Hall effect.

FIG. 9 is a circuit diagram showing a configuration of a high frequency heating apparatus of Example 7.

FIG. 10 is a circuit diagram showing a configuration of a high frequency heating apparatus of Example 8.

FIG. 11 is a circuit diagram showing a configuration of a high frequency heating apparatus of Example 9.

FIG. 12 is a circuit diagram showing a configuration of a high frequency heating apparatus of Example 10.

FIG. 13 is a circuit diagram showing a configuration of a conventional heating cooker.

[Explanation of Codes] 1 commercial AC power supply, 2 rectification smoothing circuit, 3 leakage transformer (transformer), 4 switching element, 7 magnetic detection means, 8 drive control circuit, 10 magnetron, 13 circuit board, 14 formed on board Spiral pattern wiring, 16 circuit patterns, 200 induction heating coil.

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 13

[Correction method] Change

[Correction content]

[Fig. 13]

Claims (6)

[Claims] 1. A rectifying / smoothing circuit for rectifying and smoothing a commercial AC power supply, converting the output of the rectifying / smoothing circuit to a high frequency, and supplying high frequency power to a magnetron through a transformer or supplying high frequency power to an inductor. A switching element, and a magnetic detection unit that is disposed in the vicinity of the transformer or the inductor, detects a leakage magnetic flux from the transformer or the inductor, and outputs a detection signal corresponding to a voltage applied to the switching element, A heating cooker comprising: drive control means for driving the switching element based on a detection signal from the magnetic detection means. 2. A rectifying / smoothing circuit for rectifying and smoothing a commercial AC power supply, converting the output of the rectifying / smoothing circuit to a high frequency, and supplying the magnetron with high frequency power via a transformer or supplying high frequency power to an inductor. A switching element and a magnetic detector which is arranged in the vicinity of the transformer or the inductor, detects a leakage magnetic flux from the transformer or the inductor, and outputs a detection signal when the voltage applied to the switching element becomes zero. A heating cooker comprising: means and drive control means for driving the switching element based on a detection signal from the magnetic detection means. 3. A rectifying / smoothing circuit for rectifying and smoothing a commercial AC power source, converting the output of the rectifying / smoothing circuit to a high frequency, and supplying the magnetron with high frequency power via a transformer or supplying high frequency power to an inductor. A switching element and a transformer or inductor arranged near the transformer to detect a leakage magnetic flux from the transformer or the inductor, output a detection signal corresponding to the voltage applied to the switching element and delayed by a predetermined time. And a drive control means for driving the switching element based on a detection signal from the magnetic detection means. 4. A rectifying / smoothing circuit for rectifying and smoothing a commercial AC power source, and a switching for converting the output of the rectifying / smoothing circuit into a high frequency and supplying the high frequency power to a magnetron through a transformer or supplying the high frequency power to an inductor. A magnetic element that is arranged in the vicinity of the element and the transformer or the inductor, detects the leakage magnetic flux from the transformer or the inductor, and the applied voltage of the switching element becomes zero, and outputs a detection signal after a lapse of a predetermined time. A heating cooker comprising a detection means and a drive control means for driving the switching element based on a detection signal from the magnetic detection means. 5. The heating cooker according to claim 1, wherein the drive control means is further supplied with power from a cooking control board for controlling the cooker. . 6. The heating cooker according to claim 1, wherein the magnetic detecting means has a spiral pattern wiring formed on a substrate.