JPH11149979A - Cooker - Google Patents

Abstract

(57) Abstract: An object of the present invention is to reduce high frequency noise of a cooking device having a frequency conversion device with a simple configuration. SOLUTION: A power line and an earth line are made to penetrate through the opening surface of a ring core 13 from opposite directions to thereby substantially reduce power consumption.
It is possible to provide a cooking device equipped with an inexpensive frequency converter that effectively reduces high-frequency noise of 0 MHz or more and has little leakage noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for preventing leakage noise of a cooking device provided with a frequency converter such as an inverter.

[0002]

2. Description of the Related Art Heating cookers such as induction heating cookers provided with a frequency converter for converting a low frequency to a high frequency by a switching element have been developed.

[0003] A conventional heating cooker will be described below. FIG. 6 is a block circuit diagram of a conventional induction heating cooker having an inverter. An input terminal A and an input terminal B are connected to the commercial power supply 1. Reference numeral 11 indicated by an alternate long and short dash line indicates a housing made of a metal component, and is connected to the ground coil 3 via a terminal F. The ground coil 3 is an inductor in which a conductive wire is wound around a ring-shaped ferrite core by several turns.
Is connected to the ground wire.

An electric wire between the terminals A and D and an electric wire between the terminals B and D pass through the opening of the ring core 2 made of ferrite. The capacitor 4 between the power supply lines, the common mode coil 5, and the capacitor 6 and the capacitor 7 connected between the power supply and the housing 11 constitute a filter circuit, and the rectifier 8
, And terminals D and E.
The output terminal of the rectifier 8 is provided with an inverter 9 to which a heating coil 10 is connected.

In FIG. 6, the electric wire between the terminals A and D and the electric wire between the terminals B and E only penetrate through the opening surface of the ring core 2, but are the same as in FIG. In some cases, the wires may be simultaneously wound in the same direction, or three wires including the ground wire between the terminals C and D may be simultaneously wound in the same direction as shown in FIG.

[0006]

In the above-mentioned cooking device, the ring core 2 or the earth coil 3 has a filtering amount of about 10 MHz which is not sufficient in a filtering circuit composed of the capacitor 4, the common mode coil 5 and the capacitors 6, 7. The above-mentioned high frequency noise is prevented from leaking to the commercial power supply 1 or the ground via the input power supply line or the ground line, and the configuration of FIG. 7 requires two ferrite cores, which is simpler and less expensive. Configuration is required.

SUMMARY OF THE INVENTION It is an object of the present invention to efficiently reduce high frequency noise having a frequency of 10 MHz or more leaked to the outside via an input power supply line and a ground line with a simple configuration.

[0008]

In order to solve this problem, a heating cooker according to the present invention comprises a housing for accommodating a frequency converter, a power supply line for supplying power to the frequency converter, A ground line that grounds the body, and an annular magnetic body that penetrates the power supply line and the ground line through the opening thereof, wherein the magnetic body is configured such that the input sides of the power supply line and the ground line are connected to each other with respect to the opening. In this way, the impedance of the ground wire at high frequencies is increased, and at the same time, the high-frequency noise current that leaks to the outside and returns through the ground wire to leak from the power supply line to the outside is attempted. A heating cooker equipped with a frequency conversion device in which high-frequency noise is eliminated and high-frequency noise having a frequency of 10 MHz or more is effectively reduced with a simple configuration can be obtained.

[0009]

The invention according to claim 1 is characterized in that a housing for accommodating the frequency converter, a power line for supplying power to the frequency converter, a ground line for grounding the housing, An annular magnetic body that penetrates a wire and a ground wire through an opening surface thereof, wherein the magnetic body is configured such that input sides of the power supply line and the ground wire penetrate in opposite directions to each other with respect to the opening surface. The high-frequency noise generated from the frequency converter mounted on the cooking device and about to leak to the commercial power supply via the input power supply line is increased, and at the same time, the high-frequency impedance of the ground line is increased, and at the same time, the power supply is connected via the ground line. Approximately 1 to cancel each other with high frequency noise returning to the cooking device
High frequency noise of a frequency of 0 MHz or more can be more effectively reduced with a simple configuration.

[0010] The invention according to claim 2 is to increase the high frequency impedance of the ground line further by simultaneously increasing the number of times that the ground line penetrates the opening surface of the magnetic body, and at the same time, the high frequency leaking from the power supply line. Increase the amount of the current that returns the noise to the ground wire to cancel out, and increase the frequency to 10 MHz.
This has the effect that the effect of reducing the leakage noise at the above frequencies can be further enhanced.

The invention according to claim 3 is characterized in that the ring-shaped magnetic material is made of manganese-zinc ferrite, so that the ferrite core of about 2 MHz to about 15 MHz as seen when a ferrite core of nickel is used. And the effect of reducing the leakage noise according to claim 1 or 2 can be effectively exerted in that frequency band.

[0012]

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block circuit diagram of an induction heating cooker having an inverter. A power input terminal a and a power input terminal b are connected to the commercial power supply 12. Reference numeral 21 indicated by an alternate long and short dash line indicates a housing made of metal parts, and a housing connection terminal c is connected to the housing 21. A ground wire (ground wire) having one end connected to the external ground is connected to a ground input terminal f inside the housing 21.

An electric wire between the power input terminals a and d and an electric wire between the power input terminals b and d are arranged such that the power input terminals a and b are on the same side with respect to the opening surface of the ring core 13. So that the outer diameter is about 25mm, the inner diameter is about 10mm,
It penetrates a ring core 13 made of Mn (manganese) -Zn (zinc) ferrite having a width of about 12 mm. The electric wire between the ground input terminal f and the housing connection terminal c is connected to the ring core such that the ground input terminal f is in the opposite direction to the power input terminals a and b with respect to the opening surface of the ring core 13. 13 through the opening surface.

The capacitor 16 and the capacitor 17 connected between the power supply input line and the common mode coil 15 and between the power supply and the housing 21 are filter circuits.
8 input terminals and terminals d and e.
An inverter 19 to which a heating coil 20 is connected is provided at an output terminal of the rectifier 18.

The operation of the heating cooker configured as described above will be described. The high frequency noise generated from the inverter 19 is transmitted to the capacitor 14 and the common mode coil 1
Filtering is performed by a filter circuit composed of a capacitor 16 and a capacitor 17 connected between the power supply 5 and the power supply-housing 11, and leakage to the power supply 12 is suppressed. However, since the input power supply line of the filter circuit itself or the input side of the filter coil is directly coupled to the high-frequency generation source of the inverter 19 via the ground wire, the solid line a in FIG. 10 MH as shown
In the vicinity of z, high frequency noise having a resonance point and leaking to the power supply line may increase. The noise in this frequency band is not completely filtered out by the above-described filter circuit, and the leakage level cannot be reduced by measures such as changing the capacitance values of the capacitors 16 and 17.

In this embodiment, the power line between the power input terminals a and d and the power line between the power input terminals b and d are formed on the opening surface of the ring core 13 as described above. The power input terminal a and the power input terminal b are on the same side with respect to the opening surface, and the electric wire between the ground input terminal f and the housing connection terminal c is connected to the ground surface with respect to the opening surface of the ring core 13. By penetrating the opening of the ring core 13 so that the terminal f is in the opposite direction to the power input terminal a and the power input terminal b, the high-frequency impedance of the ground wire is increased, and the return current flowing through the ground wire is reduced by the power supply. As shown by the dashed line b in FIG.
The peak of the nearby high-frequency noise level is reduced by about 5 dB.

As described above, according to the present embodiment, of the two input power lines and the ground line, two power lines pass through the opening of the ring core 13 in the same direction, and only the ground line is Since it penetrates through the opening of the ring core 13 in the opposite direction to the power supply line, the high frequency impedance of the ground line is increased, and the feedback current flowing through the ground line cancels out the high frequency noise that is about to leak from the power supply line. Join
Leakage of high-frequency noise in the vicinity of about 10 MHz can be effectively suppressed by one ferrite core.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described with reference to FIG. As in FIG. 1, two power supply lines pass through the opening surface of the manganese-zinc-based ring core 22 once so that each input side (power supply side) is in the same direction with respect to the opening surface. The difference from FIG. 1 is that only the ground wire penetrates the opening surface of the ring core 22 three times.

With the above configuration, it is possible to further increase the high-frequency impedance of the ground wire, and at the same time, to increase the amount of high-frequency noise leaking from the power supply line to be canceled out by the current returning to the ground wire. As shown by, even if a ring core of the same material and the same shape is used, it is possible to reduce about 9 dB as compared with the configuration of the first embodiment.

FIG. 4 differs from the configuration of FIG. 2 only in the leakage noise level (indicated by the dashed line h) in the case of the configuration of FIG. 2 and the direction in which the ground wire passes through the opening of the ring core 22. (The number of times the ground wire penetrates the opening surface of the ring core 22 is the same at three times, and the power line and the ground wire pass through the opening surface of the ring core 22 from the same direction) (shown by a solid line g). 3) shows the result of comparison by measuring experimentally. As shown in FIG. 2, in the case of the configuration of FIG. 2, since the high frequency component of the feedback current flowing through the ground line cancels out the leakage noise of the power supply line, the leakage noise level is about 4 to 30 MHz in the frequency band of about 10 to 30 MHz. 6
The effect of reducing the dB is increased.

As described above, according to this embodiment, two power supply lines are passed through the ring core 22 once, and the ground wire is passed through the ring core three times from the opposite direction. At the same time, it is possible to reduce the leakage of high-frequency noise more effectively with a single ferrite core because the return current of the high-frequency noise flowing through the ground wire increases the effect of canceling the high-frequency noise that is about to leak from the power supply. It is.

FIG. 5 shows a leakage noise level (indicated by a dashed line f) when the material of the ring core 22 is a manganese-zinc ferrite and a structure similar to that of the first embodiment. Noise level in the case (broken line e
), And the result of comparing and measuring the leakage noise level (shown by a solid line d) without the ring core 22 by experiment. As shown in FIG. 5, when the material of the ring core 22 is a nickel-zinc ferrite, about 2 to 15 MH
The noise suppression effect decreases near z, and in the case of manganese-zinc-based ferrite, the reduction amount of the suppression effect is small, and as a result of the above measurement, the latter has a lower leakage level of about 7 dB high frequency noise. Also, the peak around 10 MHz is reduced by about 4 dB.

As described above, according to the present embodiment, two power supply lines are made to pass through the ring core 22 once in the same direction, and the ground line is made to pass through three times from the opposite direction. 1, the high frequency noise flowing back through the ground wire can be counteracted and attenuated by the action of the ring core, and the feedback current of the high frequency noise flowing through the ground wire can be reduced and attenuated by a single ferrite core. It is.

In the first or second embodiment,
By using a manganese-zinc-based ferrite as the material of the ring core 22, there is no reduction in the suppression effect at about 2 to about 15 MHz as seen when a nickel-based ferrite core is used, and the frequency band in the frequency band. It is possible to effectively use the leakage noise reduction function of 1 or 2.

In the above embodiment, the configuration of the induction heating cooker having the frequency converter is shown. However, the present invention is not limited to this. The same effect can be obtained by using the core to form the power supply line and the ground line as described above.

[0027]

As described above, according to the first aspect of the present invention, a housing for accommodating the frequency converter, a power supply line for supplying power to the frequency converter, and a ground for grounding the housing. And a ring-shaped magnetic body that penetrates the power supply line and the ground line through the opening thereof, wherein the magnetic body penetrates the input sides of the power supply line and the ground line in mutually opposite directions with respect to the opening. It is generated from the frequency conversion device,
About 1 that tries to leak to commercial power via input power line
A high-frequency cooker equipped with an inexpensive frequency conversion device that can reduce high-frequency noise at a frequency of 0 MHz or more with a simple configuration without increasing the number of components and that has a low frequency noise. It is.

According to the second aspect of the present invention, in particular, since the number of times that the ground wire passes through the opening of the magnetic body is set to a plurality of times, the high-frequency impedance of the ground wire is further increased, and at the same time, the ground wire leaks from the power supply line. Increase the amount of current that returns high-frequency noise back to the ground wire, and increase the frequency to 10 MHz.
It is possible to provide an inexpensive heating cooker with less leakage noise at the above frequencies.

According to the third aspect of the invention, in particular, since the material of the magnetic material is a manganese-zinc ferrite, a cooking device having less leakage noise in a frequency band of about 2 to about 30 MHz is provided. That can be provided.

[Brief description of the drawings]

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

FIG. 2 is a perspective view of a main part around a magnetic body of a cooking device according to a second embodiment of the present invention.

FIG. 3 is a characteristic diagram of a noise level of the cooking device according to the first and second embodiments of the present invention.

FIG. 4 is a characteristic diagram of a noise level of the cooking device according to the second embodiment of the present invention.

FIG. 5 is a characteristic diagram of a noise level according to a material difference of a magnetic material of the cooking device.

FIG. 6 is a circuit block diagram of a conventional cooking device;

FIG. 7 is a perspective view of a main part around a magnetic body of the cooking device.

FIG. 8 is a perspective view of an essential part around another magnetic body of the cooking device.

[Explanation of symbols]

 12 Commercial power supply (power supply) 13 Ring core (annular magnetic body) 19 Inverter (frequency converter) 20 Heating coil (frequency converter) 21 Housing 22 Ring core (annular magnetic body)

Claims (3)

[Claims] 1. A housing for accommodating a frequency conversion device, a power supply line for supplying power to the frequency conversion device, a ground line for grounding the housing, and the power supply line and the ground line penetrating through the opening. A heating magnetic cooker comprising: a ring-shaped magnetic material; and the magnetic material having input sides of the power supply line and the ground line penetrated in opposite directions with respect to the opening surface. 2. The cooking device according to claim 1, wherein the number of times that the ground wire passes through the opening surface of the magnetic material is a plurality of times. 3. The cooking device according to claim 1, wherein the material of the magnetic material is manganese-zinc ferrite.