JP2002325429A - Secondary rectification noise-reduction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance noise-reducing effects with respect to higher harmonics and to provide an inexpensive secondary current noise reducing device. SOLUTION: A conductor 1 is successively folded into rectangles, having opposite portions 1a and 1b and folded portions 1c and 1d.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary rectification noise reduction device used in various power supply devices to reduce noise.

[0002]

2. Description of the Related Art Generally, in a power supply device such as a switching regulator, various secondary rectification noises as shown in FIG. 5 are generated because a voltage is switched at a high speed. These noises are roughly classified into radiation noise radiated into the air and conduction noise transmitted to the AC power supply line. Further, conduction noise is divided into common mode noise and normal mode noise. Common mode noise is the spike voltage generated by the switching element,
The current is mainly caused by the current passing through the capacitance between the case of the switching element and the heat sink or the capacitance between the primary and secondary of the transformer.

On the other hand, as shown in FIG. 6, normal mode noise is mainly generated by switching discharge due to the inductor component of the storage capacitor CS and current spikes when the rectifier diode is turned off. That is, the storage capacitor CS stores the energy supplied from the AC line through the rectifying diode bridge, and this energy is transmitted to the converter circuit and the like by discharging by the switching operation. Since this storage capacitor CS includes not only a pure capacitance component but also a series resistance component and an inductance component equivalently, a voltage drop occurs due to a discharge current flowing at the time of discharge. And a normal mode current flows through the AC line.
Accordingly, the impedance of this noise source is relatively low because it is the residual resistance of the storage capacitor CS, the inductance component, and the conduction resistance of the rectifier diode.

Further, a current spike generated when the rectifier diode is turned off is coupled to an AC line by a PN junction capacitance of the rectifier diode which is reverse-biased, or a pattern of a printed circuit board on which these electronic components are mounted. Or through the parasitic capacitance of the transformer. Since the rectifier diode is turned on and off at twice the AC power supply frequency, the noise generated by these rectifier diodes contains a harmonic component twice the power supply frequency.

As a countermeasure against the generated noise, a common mode choke as shown in FIG. 7A is used for the common mode noise, and as shown in FIG. Was used at the entrance. on the other hand,
For normal mode noise, as shown in FIG.
The normal mode coil 10 has been used together with the noise filters 11 and 12 to reduce harmonic components.
The normal mode coil 10 is formed by winding a coil around a core material such as ferrite or permalloy.

[0006]

However, in the above-described normal mode coil, the impedance is determined mainly by the magnetic permeability of the core material and the number of turns of the coil. The larger the impedance, the greater the noise reduction effect. Generally, inexpensive ferrite or permalloy is used for the core of the normal mode coil, but in order to obtain higher impedance, a material having a higher magnetic permeability than ferrite, such as a nanocrystalline soft magnetic material, is used. Had become expensive. In addition, since these normal mode coils use a core material, their frequency characteristics are limited by the core material, and have a sufficient effect on harmonics ranging from 30 MHz to 100 MHz. There was also a problem that it could not be obtained.

The present invention has been made in view of the conventional problems, and an object thereof is to provide an inexpensive secondary current noise reduction device that enhances the noise reduction effect on harmonics.

[0008]

In order to achieve the above object, a secondary rectification noise reduction device according to the present invention according to claim 1 is characterized in that the conductor is formed by continuously folding so as to have an opposed portion and a folded portion. It is characterized by. According to the above configuration,
Since the currents flowing in the opposite parts of the conductors are in opposite directions,
The directions of the electromagnetic fields generated in the conductors are also opposite to each other, and act to cancel each other. Therefore, the harmonics generated in the conductor also have the opposite phases, and are canceled each other.

Further, in the secondary rectification noise reduction device according to the present invention, the total length of the conductor is １ ／ of a wavelength of a main harmonic generated by an electronic device to which the conductor is attached.
Or the same length. According to the above configuration, the frequency of the main harmonic generated by the electronic device used and the frequency tuned by the conductor are set to be the same, so that the harmonic can be canceled efficiently.

According to a third aspect of the present invention, there is provided a secondary rectification noise reduction device, wherein conductor units formed by continuously folding conductors having opposing portions and folded portions are vertically chained so as to face in opposite directions to each other. It is characterized by having crossed.
According to the above configuration, since the currents flowing in the upper and lower conductors are in opposite directions, the directions of the electromagnetic waves generated in the conductors are also opposite to each other, and act to cancel each other. Therefore, the harmonics generated in the conductor also have the opposite phases, and are canceled each other, so that the secondary rectification noise can be reduced.

Further, the secondary rectification noise reduction device according to the present invention is a secondary rectification noise reduction device characterized in that one of the conductor units is connected to the ground. According to the above configuration, since the currents flowing in the upper and lower conductors are in opposite directions, the directions of the electromagnetic waves generated in the conductors are also opposite to each other, and act to cancel each other. Furthermore, the harmonic components remaining without completely canceling each other are grounded, so that the secondary rectification noise can be reduced more effectively.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
The third to third embodiments will be described. FIG. 1 shows a first embodiment of the present invention. As shown in FIG. 1, the secondary rectification noise reduction device A includes a
It is formed by successively folding a rectangular shape having a, 1b and folded portions 1c, 1d. Opposing portions 1a and 1b of the conductor 1 have the same dimensions,
c and 1d are also formed in the same size. Also, the opposing part 1
a, 1b and the folded portions 1c, 1d have a relational dimension of the facing portion 1.
a, 1b> return portions 1c, 1d.
The material used for the conductor 1 of the secondary rectification noise reduction device A may be a metal wire having good conductivity, such as copper, but can be realized by using a pattern of a printed circuit board.

Further, the length of the conductor 1 of the secondary rectification noise reduction device A is set to be １ ／ to the same length as the wavelength of the main harmonic generated by the electronic equipment to be used. The tuning is performed by the length of the conductor 1.
That is, in the case of a switching regulator or the like, the generated harmonic reaches 100 MHz, and when this wavelength (λ) is calculated in order to attenuate the 100 MHz harmonic, the wavelength (λ) = the speed (3 × 10 8 m) ) / Frequency (10
0 × 10 6 Hz), the wavelength (λ) is 3 m. In order to attenuate the most efficiently, it is preferable to use the same wavelength of 3 m, which has the highest gain and tunes. Since tuning is performed, up to 1/4 of the wavelength can be used in practical use. In particular, a wavelength of 有効 wavelength is effective when there is a restriction on space. The inductance (L) required for the conductor 1 is about 2.2 μH at the maximum, and usually 0.5 μH is sufficient.

In the secondary rectification noise reduction device A thus configured, the current I flowing through the opposing portions 1a and 1b of the conductor 1 is
Since a and Ib have the same size and directions opposite to each other, the directions of the electromagnetic fields generated in the facing portions 1a and 1b are also opposite to each other, and act to cancel each other. Accordingly, the harmonics generated in the facing portions 1a and 1b also have opposite phases, and are canceled each other. Therefore, harmonics are canceled out as a whole of the conductor 1, so that secondary rectification noise generated in the entire electronic device is also reduced.

As shown in FIG. 2, a capacitor and a resistor may be inserted between the facing portions 1a and 1b of the conductor 1 in the secondary rectification noise reduction device A shown in FIG.

FIG. 3 shows a second embodiment of the present invention. As shown in FIG. 3, the secondary rectification noise reduction device B
As in the secondary rectification noise reduction device A, the conductor unit 2 'is formed by forming the conductor 2 into the opposing portions 2a, 2b and the folded portions 2c, 2d and successively folding the conductor 2 in a rectangular shape. Similarly, the opposing portion 3 is made of a slightly smaller conductor 3.
The conductor units 3 'are formed by forming folded portions 3c and 3d with the portions a and 3b and successively folding them in a rectangular shape. The secondary rectification noise reduction device B is configured by superposing a conductor unit 3 'vertically on the conductor unit 2' so as to face in opposite directions. In this case, a place where the conductor unit 2 'and the conductor unit 3' intersect occurs. However, the place may be insulated with an insulating material so as not to cause a short circuit, or one of the conductor units 3 'may be made a jumper wire. It may be spatially separated.

The secondary rectification noise reduction device B having the above-described configuration is used to reduce the currents Ic and If flowing through the upper and lower conductors 2 and 3;
Since Id and Ig are opposite to each other, the directions of the electromagnetic fields generated in this conductor are also opposite to each other, and act to cancel each other. Therefore, the harmonics generated in the conductors 2 and 3 also have opposite phases, and are canceled each other. Therefore, similarly to the secondary rectification noise reduction device A, the secondary rectification noise generated in the entire electronic device is also reduced.

FIG. 4 shows a third embodiment of the present invention. In the secondary rectification noise reduction device C shown in FIG.
The conductor unit 2 'is formed by forming folded portions 2c and 2d with the portions a and 2b and successively folding the rectangular portions. Similarly, opposing portions 3a, 3b
And the folded portions 3c and 3d are formed, and the conductor unit 3 'is formed by successively folding in a rectangular shape.
The secondary rectification noise reduction device C is constructed by superimposing a conductor unit 3 'on a conductor unit 2' so as to face in opposite directions, and connecting one conductor unit 3 'to a ground 5 with a ground wire. ing.

In the secondary rectification noise reduction device C configured as described above, the currents flowing through the upper and lower conductors 2 and 3 are opposite to each other, and the directions of the electromagnetic fields generated in these conductors are also opposite to each other. Act to cancel each other out. Therefore, the harmonics generated in the conductor also have the opposite phases, and are canceled each other. Therefore, similarly to the secondary rectification noise reduction device A, the secondary rectification noise generated in the entire electronic device is also reduced. Furthermore, since the harmonic components remaining without being completely canceled are grounded,
Noise can be reduced more effectively.

According to the first to third embodiments, harmonics generated in various power supply devices such as a switching regulator, an inverter, and a converter can be efficiently attenuated without using an expensive normal mode coil. And a secondary rectification noise reduction device can be provided at low cost.

It should be noted that the present invention is not limited to the above-described embodiment, and various embodiments are possible within the scope of the appended claims. For example, the thickness, shape, inductance, and the like of the conductor can be appropriately changed.

[0022]

According to the present invention, since the conductor is formed by successively folding the conductor into a rectangular shape having the facing portion and the folded portion, the currents flowing through the facing portions of the conductor are opposite to each other. The directions of the generated electromagnetic waves are also opposite to each other, and act to cancel each other. Therefore, the harmonics generated in this conductor also have the opposite phase, so that they cancel each other out, and the harmonics generated in various power supply devices can be efficiently attenuated, and an expensive normal mode coil is used. Without this, it is possible to provide a secondary rectification noise reduction device at low cost.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram showing a secondary rectification noise reduction device according to a first embodiment of the present invention.

FIG. 2 is a circuit configuration diagram showing a modified example of the secondary rectification noise reduction device shown in FIG.

FIG. 3 is a circuit configuration diagram illustrating a secondary rectification noise reduction device according to a second embodiment of the present invention.

FIG. 4 is a circuit configuration diagram showing a secondary rectification noise reduction device according to a third embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a state of generation of noise in a conventional electronic device.

FIG. 6 is a circuit diagram showing a conventional normal mode noise generation state.

FIG. 7 shows a conventional common mode choke,
(A) is a front view showing the structure of a common mode choke,
(B) is an equivalent circuit diagram showing an example of using a common mode choke.

FIG. 8 is a circuit diagram showing a conventional normal mode coil.

[Explanation of symbols]

 A Secondary Rectification Noise Reduction Device B Secondary Rectification Noise Reduction Device C Secondary Rectification Noise Reduction Device

Claims (4)

[Claims] 1. A secondary rectification noise reduction device, wherein a conductor is continuously folded so as to have an opposed portion and a folded portion. 2. The secondary rectification noise reduction device according to claim 1, wherein the total length of the conductor is set to be １ ／ to the same length as the wavelength of the generated harmonic. 3. A secondary rectification noise reduction device, wherein conductor units formed by successively folding conductors having opposed portions and folded portions are vertically linked so as to face in opposite directions. 4. A secondary rectification noise reduction device according to claim 3, wherein one of said conductor units is connected to ground.