JP2002186184A - Method and system for noise reduction and power- receiving cord - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for noise reduction, wherein if high electromagnetic noise is emitted to the air from a body of equipment or high electromagnetic noise flows into an enclosure of the equipment, electromagnetic noise superposed on a power receiving cord, especially, power supply conduction noise of unbalanced components, can be reduced. SOLUTION: A grounding system of the power receiving cord and the equipment is improved, to prevent electromagnetic noise emitted inside the equipment from being superposed on the power receiving cord. The phase and the noise amount of electromagnetic noise superposed on a ground wire 3 and feeders 5 of the power receiving cord due to the coupling of electromagnetic noise emitted to the outside of the equipment with the ground wire 3 and the feeders 5, are made substantially equal to each other, to reduce a potential difference between the ground wire 3 and the feeders 5, with respect to the above electromagnetic noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and system for reducing noise of unbalanced components and a power receiving cord.

[0002]

2. Description of the Related Art Conventionally, in order to reduce power transmission noise, a noise filter (low-pass filter) has been added to a power supply circuit of a device, or a power cord with a noise filter has been used. As a prior art for reducing such power supply conduction noise, Japanese Unexamined Utility Model Publication No. 63-065910 discloses a technique of adding a noise filter in a power receiving plug to integrate with a cord to reduce power supply conduction noise. Power cord ".

FIG. 9 is a circuit conceptual diagram showing the configuration of such a conventional noise reduction system. An electromagnetic noise source 110 radiating electromagnetic noise 117 and a noise filter 104 are present in a housing 109. Noise filter 10
The ground wire of No. 4 is internally connected to the metal case,
Since the noise filter 104 is attached to the case 109, the case 109 and the metal case of the noise filter 104 are in a state of being electrically connected. The power receiving cord has a structure including a pair of power supply lines 105 and a ground line 113, and a power receiving plug 116 is formed at the end thereof. Some power receiving plugs 116 have a built-in noise filter. A power supply plug 102 is formed at the other end of the power receiving cord, and power taken in through the power receiving plug 116 is supplied to a power supply circuit such as a switching regulator inside the housing 109 via the power supply plug 102 and the noise filter 104. Is done.

As described above, there are many techniques that have been widely used in the past to reduce power supply conduction noise, in which a noise filter 104 is added to a power supply circuit. For example, a noise filter 104 is provided on the path that leaks out through the power receiving cord.
Is added to prevent the switching noise from flowing out of the device or to prevent noise from entering from outside via the power receiving cord. That is,
The noise source is located in the power supply circuit to prevent the power receiving cord from being transmitted and leaking to the outside, or to prevent noise from entering the power supply circuit through the power receiving cord from other sources.

[0005]

Since the conventional noise reduction system is configured as described above, the first problem is that a device such as a plasma display which emits electromagnetic noise 118 radiated into the air is large. Also, in a device in which noise superimposed on the housing is large, as shown in FIG. 9, the electromagnetic noise 117 generated from the electromagnetic noise source 110 on the power receiving plug 116 side of the noise filter 104 causes 108 and electromagnetic noise 118 radiated into the air will couple to the power cord,
From the viewpoint of suppressing noise leaking outside through the power receiving cord, there is a problem that the noise suppression effect of the noise filter 104 cannot be obtained.

In such a case, it is effective to use a power cord in which a noise filter is added to the power receiving plug 116. However, since the noise filter is added to the power receiving plug 116, the size of the plug can be increased. There is a problem that higher prices cannot be avoided.

Accordingly, an object of the present invention is to provide a power supply for electromagnetic noise, especially unbalanced components, which is superimposed on a power receiving cord when electromagnetic noise radiated from the main body of the device into the air or electromagnetic noise flowing through the housing of the device is large. It is an object of the present invention to provide a noise reduction method capable of reducing conduction noise.

Another object of the present invention is to provide an electromagnetic noise superimposed due to coupling with electromagnetic noise radiated from the main body of the device into the air or electromagnetic noise flowing through the housing of the device, especially power supply of unbalanced components. An object of the present invention is to provide a noise reduction method and a power receiving cord that can suppress noise without increasing the size and the price.

[0009]

According to the noise reduction method of the present invention, the ground line and the power supply line are formed by making the electromagnetic noise superimposed on the ground line and the power supply line of the power receiving cord substantially in phase and in substantially the same amount. A potential difference caused by the electromagnetic noise between the power supply line and the ground line is relatively reduced.

The noise reduction method according to the present invention is a noise reduction method for reducing power supply conduction noise caused by coupling of electromagnetic noise radiated from a device connected to a power receiving cord having a ground line and a power supply line to the power receiving cord. Reduction method,
By making the electromagnetic noise radiated from the device and superimposed on the ground line and the feed line of the power receiving cord substantially in phase and in substantially the same amount, the potential difference due to the electromagnetic noise between the ground line and the feed line is eliminated, An electromagnetic noise between the power supply line and the ground line is relatively reduced.

A power receiving cord according to the present invention includes a ground wire and a power supply line, and supplies power supplied from the power receiving plug to a device connected through the power supply plug. A disconnection portion is formed in the ground line.

According to the noise reduction method of the present invention, the electromagnetic noise superimposed on the ground line and the power supply line of the power receiving cord is made to have substantially the same phase and substantially the same amount, so that the electromagnetic noise between the ground line and the power supply line is provided. To reduce the electromagnetic noise between the power supply line and the ground line, and superimpose on the power receiving cord due to the electromagnetic noise radiated from the device body into the air or the electromagnetic noise flowing through the housing of the device. Electromagnetic noise,
In particular, the power supply conduction noise of the unbalanced component is reduced.

According to the noise reduction method of the present invention, the electromagnetic noise superimposed on the ground line and the power supply line of the power receiving cord is made substantially in-phase and substantially the same amount by the electromagnetic noise radiated from the device, and the ground line and the power supply line are provided. To eliminate the potential difference due to the electromagnetic noise between the power supply line and the grounding line, and to relatively reduce the electromagnetic noise between the power supply line and the ground line. Reduces noise, especially power conducted noise of unbalanced components.

According to the power receiving cord of the present invention, the power receiving cord for supplying the power supplied from the power receiving plug to the device via the power supply plug is formed in the ground wire near the power supply plug by forming a broken portion. Eliminate the potential difference due to the electromagnetic noise between the ground line and the power supply line, relatively reduce the electromagnetic noise between the power supply line and the ground line, and transmit the electromagnetic noise radiated from the device to the power receiving cord. Coupling makes it possible to reduce superimposed electromagnetic noise, in particular, power supply noise of unbalanced components.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below. FIG. 1 is a circuit conceptual diagram showing a configuration of a noise reduction system including a power receiving cord according to this embodiment. An electromagnetic noise source 10 radiating an electromagnetic noise 7 is provided in a case 9.
And the noise filter 4, the ground wire of the noise filter 4 is internally connected to the metal case, and the noise filter 4 is directly attached to the case 9. The filter 4 is electrically connected to the metal case. The power receiving cord has a structure including a pair of power supply wires 5 and a ground wire 3, and a power receiving plug 6 is formed at the tip thereof. The ground wire 3 of the power receiving cord is cut by the disconnection portion 1 in the power supply plug 2 formed at the other end of the power receiving cord, and the ground wire 13 inside the device drawn out of the noise filter 4 is connected.
And not connected. The power taken in via the power receiving plug 6 of the power receiving cord is supplied to a power supply circuit such as a switching regulator inside the box 9 via the power supply plug 2 and the noise filter 4.

Reference numeral 8 denotes electromagnetic noise flowing through the case 9, the ground wire 12 of the device, the metal case of the noise filter 4, and the ground wire 13 drawn from the noise filter 4, and reference numeral 11 denotes an electromagnetic noise source 10. Is electromagnetic noise radiated from the air into the air.

Next, the operation will be described. The connection between the ground wire 3 of the power receiving cord and the housing 9 of the device is discontinuous by providing a disconnection portion 1, and the electromagnetic noise 8 flowing through the housing 9 is reduced by the ground wire 12 of the device and the noise filter 4. Metal case and the ground wire 1 drawn from the noise filter 4
3 to prevent it from flowing out of the housing 9 to the outside.

In this embodiment, the broken portion 1 of the ground wire 3 of the power receiving cord is formed in the power supply plug 2, whereby the ground wire 13 of the device and the ground wire 13 drawn from the noise filter 4 and the power receiving cord are connected. And is not electrically connected to the ground line 3. The electromagnetic noise source 10 emits the electromagnetic noise 7 inside the device, and also emits the electromagnetic noise 11 outside the device. Thereby, the electromagnetic noise 7 in the device is superimposed on the housing 9 as the electromagnetic noise 8 and flows. The electromagnetic noise 8 flows out to the power receiving port of the device by the grounding wire 12 of the device and the grounding wire 13 drawn from the noise filter 4, but does not flow out to the grounding wire 3 of the subsequent power receiving cord by the disconnection portion 1. Further, the power supply line 5 of the power receiving cord is in a state where the superposition of the electromagnetic noise 7 emitted from the electromagnetic noise source 10 is suppressed by the effect of the noise filter 4 and the like.

FIG. 2 is a conceptual diagram showing a quantitative relationship of the electromagnetic noise in this embodiment. The electromagnetic noise potential V1 of the feed line 5, the electromagnetic noise potential V2 of the ground line 3, and the electromagnetic noise potential of the feed line 5 are shown. The concept is described as a potential difference V3 between V1 and the electromagnetic noise potential V2 of the ground line 3. As described above, the electromagnetic noise radiation from the inside of the device to the ground line 3 and the power supply line 5 of the power receiving cord is reduced, and the electromagnetic noise superimposed on the ground line 3 and the power supply line 5 of the power receiving cord is radiated into the air. Only the generated electromagnetic noise 11 becomes dominant. As a result, as shown in FIG. 2, the electromagnetic noise potential V1 of the power supply line 5 and the electromagnetic noise potential V2 of the ground line 3 have substantially the same phase and the same amount. As a result, the power receiving plug 6
The potential difference V3, which is the difference between the electromagnetic noise potentials of the ground line 3 and the feeder line 5 at the position shown in FIG.

FIG. 3 is a conceptual diagram showing a state of conventional electromagnetic noise superimposed on a power receiving code. In the power receiving cord of the device, the electromagnetic noise potential V1 of the power supply line 5 and the electromagnetic noise potential V2 of the ground line 3 have different amounts of electromagnetic noise and different phases. Therefore, a potential difference V3, which is a difference between the electromagnetic noise potentials of the power supply line 5 and the ground line 3, is inevitably increased. On the other hand, in this embodiment, as shown in FIG. 2, the electromagnetic noise potential V1 of the power supply line 5 and the electromagnetic noise potential V2 of the ground line 3 are in phase with each other, as shown in FIG. The potential difference V3 for noise is smaller than that in FIG. Thus, the electromagnetic noise potential V of the feed line 5
By making the electromagnetic noise potentials V2 of the first and ground lines 3 substantially the same in phase and substantially the same amount, the potential difference V3 between them can be reduced.

In this state, the power supply conduction noise is measured using the measurement auxiliary circuit shown in FIG. The circuit network shown in FIG. 4 is a circuit network specified to be used in the Electrical Appliance and Material Control Law, and is used by inserting a power receiving plug 6 into a terminal indicated by a symbol P in FIG. An AC power supply such as AC100 is supplied to the left end terminal. Further, a balanced component or an unbalanced component of the electromagnetic noise is detected from the lower right interference wave measuring device. EMI (Electroma) worldwide
The emission regulation of power supply conduction noise is provided in the standard of the “electric power compatibility” or the Electrical Appliance and Material Control Law, and it is specified that the measurement is performed using a measurement auxiliary circuit called a pseudo power supply network. The circuit shown in FIG. 4 is an example, and is a circuit diagram showing the measurement auxiliary circuit defined by the Electrical Appliance and Material Control Law. The measurement auxiliary circuit shown in FIG. 4 has a built-in changeover switch for separately measuring the balanced component and the unbalanced component.

FIG. 5 shows a measurement example when the power supply conduction noise of the unbalanced component is measured using the measurement auxiliary circuit shown in FIG. 4 with and without the disconnection portion 1 in the power supply plug 2. The power transmission noise voltage V5 of the unbalanced component when the disconnection portion 1 is provided is smaller than the power transmission noise voltage V4 of the unbalanced component when the disconnection portion 1 is not provided, and is at most 10 dB (approximately). A reduction effect of 1/3 or more can be confirmed.

As described above, according to this embodiment,
Conventionally, the electromagnetic noise 7 emitted from the electromagnetic noise source 10
Is superimposed on the housing 9 and the electromagnetic noise 8
The electromagnetic noise that has flowed out to the ground line 3 of the power receiving cord via 2 stops flowing due to the broken portion 1, while the electromagnetic noise 7 does not flow through the power supply line 5 of the power receiving cord due to the function of the noise filter 4. For this reason, superposition of electromagnetic noise is reduced in the power supply plug 2 of the device-side power receiving port, and the potential difference of the electromagnetic noise between the ground wire 3 and the power supply line 5 in the power receiving plug 6 is suppressed. That is, the grounding wire 3 of the receiving cord
Is provided in the power supply plug 2 so that the electromagnetic noise 8 superimposed on the housing 9 does not flow into the grounding wire 3 of the power receiving cord, and is discharged into the air similarly to the power feeding wire 5 of the power receiving cord. Only the electromagnetic noise 11 is superimposed on the ground wire 3 and the feed line 5 of the power receiving cord. The potential difference of the electromagnetic noise between them is reduced, and the power supply conduction noise of the unbalanced component can be reduced.

That is, the electromagnetic noise 11 generated from the electromagnetic noise source 10 and radiated into the air is superimposed on the power supply line 5 and the ground line 3 of the power receiving cord, but the phase and the electromagnetic noise amount are substantially the same. In addition, the potential difference of the electromagnetic noise between the ground line 3 and the feed line 5 can be suppressed low. This is because the disconnection portion 1 is provided in the ground wire 3 of the conventional power receiving cord, so that the noise filter 4 is close to the power supply plug 2 of the power receiving port on the device side similarly to the power supply line 5 decoupled to the device side with high impedance. , The presence of the reflected wave at the power supply plug 2 at the device-side power receiving port of the ground line 3 and the presence of the reflected wave at the power supply line 5 cause substantially the same behavior.

EMI standards other than the Electrical Appliance and Material Control Law,
For example, in the CISPR 22, the emission value is limited only for the unbalanced component specified by the Electrical Appliance and Material Control Law, so that the noise reduction method and apparatus can satisfy the EMI standard.

The electromagnetic noise 11 superimposed due to the coupling with the electromagnetic noise 11 radiated into the air from the main body of the device and the electromagnetic noise 8 flowing through the housing 9 of the device, especially the power supply noise of the unbalanced component, By providing the ground wire 3 with the disconnection portion 1, the noise can be reduced, and there is an effect that a noise reduction method and a power receiving cord that can avoid an increase in size and cost can be provided.

Next, another embodiment of the present invention will be described. FIG. 6 is a circuit conceptual diagram showing the configuration of the noise reduction system according to this embodiment. The same or corresponding parts as those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted. The difference between this embodiment and the above-described embodiment is that the above-described embodiment has a configuration in which the ground wire 3 of the power receiving cord is cut by the disconnection portion 1 in the power supply plug 2, whereas in this embodiment, the power is supplied. The ground wire inside the device or the ground wire drawn out of the noise filter 4 from the plug 2 is cut off, and the ground wire 3 of the power receiving cord is not connected to the ground wire 12 on the device side, that is, the housing 9. Connected.

FIG. 7 shows a state in which the ground line drawn from the noise filter 4 is cut off inside the device in this embodiment.
When the connection between the power receiving cord and the ground wire 3 is disconnected,
This is a measurement example when the power supply conduction noise of the unbalanced component is measured using the measurement auxiliary circuit shown in FIG. 4 when the ground line is not cut, and when the ground line is cut inside the device side. The power transmission noise voltage V7 of the balanced component is
It is lower than the power supply conduction noise voltage V6 of the unbalanced component when the ground line is not cut, and is at most 10 dB.
A reduction effect of (approximately one third) or more can be confirmed.

As described above, also in the noise reduction method and apparatus of this embodiment, the power supply line 5 and the ground line are disconnected by disconnecting the ground line of the device inside the device and disconnecting the ground line 3 of the power receiving cord. 3, the phase difference of the electromagnetic noise potential and the amount of the electromagnetic noise are substantially the same, and the potential difference of the electromagnetic noise between the power supply line 5 and the ground line 3 can be reduced. There is an effect that the power supply conduction noise voltage V7 of the unbalanced component when disconnected is lower than the power supply conduction noise voltage V6 of the unbalanced component when not disconnected.

EMI standards other than the Electrical Appliance and Material Control Law,
For example, in the CISPR 22, the emission value is limited only for the unbalanced component specified by the Electrical Appliance and Material Control Law, so that the noise reduction method and apparatus of this embodiment can also satisfy the EMI standard.

Next, another embodiment of the present invention will be described. FIG. 8 is a circuit conceptual diagram showing the configuration of the noise reduction system of this embodiment. The same or corresponding parts as those in FIG. 1 or FIG. 6 are denoted by the same reference numerals, and description thereof is omitted. This embodiment is different from the above embodiments in that a broken portion of the ground wire 3 of the power receiving cord in each embodiment and a cut portion of the ground line 13 drawn out of the noise filter 4 in the device are specified. Circuit 18 for applying an attenuation effect to the frequency and frequency band of
To give the frequency characteristics.
As a result, the same effects as those of the above embodiments can be obtained for the electromagnetic noises 7 and 8 of the specific frequency and frequency band.

[0032]

As described above, according to the present invention, the phase difference of the electromagnetic noise potential and the amount of electromagnetic noise between the power supply line and the ground line of the power receiving cord are made substantially the same, and It can reduce the potential difference of electromagnetic noise with the ground wire, and the electromagnetic noise superimposed on the power receiving cord due to electromagnetic noise radiated from the device body into the air or electromagnetic noise flowing through the device housing, especially unbalanced There is an effect that the power supply conduction noise of the component can be reduced. Further, by forming a broken portion in the ground wire near the power supply plug of the power receiving cord, a potential difference due to electromagnetic noise between the ground wire and the power feeding line of the power receiving cord can be eliminated, and the power feeding line and the ground Electromagnetic noise between wires can be relatively reduced, and electromagnetic noise radiated from the device main body is coupled to the power receiving cord, so that superimposed electromagnetic noise, particularly power supply noise of unbalanced components, can be reduced. .

[Brief description of the drawings]

FIG. 1 is a circuit conceptual diagram showing a configuration of a noise reduction system including a power receiving cord according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a quantitative relationship of electromagnetic noise according to the embodiment of the present invention.

FIG. 3 is a conceptual diagram showing a state of conventional electromagnetic noise superimposed on a power receiving code.

FIG. 4 is a circuit diagram showing a measurement auxiliary circuit defined by the Electrical Appliance and Material Control Law.

FIG. 5 is a measurement example when power supply conduction noise of an unbalanced component is measured using a measurement auxiliary circuit defined by the Electrical Appliance and Material Control Law.

FIG. 6 is a circuit conceptual diagram showing a configuration of a noise reduction system according to another embodiment of the present invention.

FIG. 7 is a measurement example when power supply conduction noise of an unbalanced component is measured using a measurement auxiliary circuit in another embodiment of the present invention.

FIG. 8 is a circuit conceptual diagram showing a configuration of a noise reduction system according to another embodiment of the present invention.

FIG. 9 is a circuit conceptual diagram showing a configuration of a conventional noise reduction method.

[Explanation of symbols]

1 disconnection portion 2 power plug 3 power cord ground wire 4 noise filter 5 power cord power supply wire 6 power plug 12 device ground wire
13: Ground wire drawn from the noise filter (ground wire inside the device).

Claims (8)

[Claims] An electromagnetic noise superimposed on a ground line and a power supply line of a power receiving cord has substantially the same phase and substantially the same amount, thereby eliminating a potential difference due to the electromagnetic noise between the ground line and the power supply line. A noise reduction method characterized by relatively reducing electromagnetic noise between a power supply line and the ground line. 2. An electromagnetic noise radiated inside the device is prevented from being superimposed on a power supply line of the power receiving cord from inside the device, and the electromagnetic noise is transmitted to the power receiving cord via a ground wire inside the device. Superimposed on the ground wire of the power cord is suppressed by a disconnection portion formed near the connection end of the ground wire of the power cord to the device, and the ground wire of the power cord due to electromagnetic noise radiated outside the device. 2. The noise reduction method according to claim 1, wherein the electromagnetic noise superimposed on the power supply line has substantially the same phase and substantially the same amount. 3. An electromagnetic noise radiated inside the device is prevented from being superimposed on a power supply line of the power receiving cord from inside the device, and the electromagnetic noise is prevented from being transmitted to the power receiving cord via a ground wire inside the device. The superimposition on the grounding line is suppressed by a disconnection formed near the connection end of the grounding line inside the device with respect to the grounding line of the power receiving cord, and the grounding of the power receiving cord due to electromagnetic noise radiated outside the device. 2. The noise reduction method according to claim 1, wherein the electromagnetic noise superimposed on the power line and the power supply line has substantially the same phase and the same amount. 4. A noise reduction system for reducing power supply conduction noise caused by coupling of electromagnetic noise radiated from a device connected to a power receiving cord having a ground wire and a power supply line to the power receiving cord, By making the electromagnetic noise radiated from the device and superimposed on the ground line and the feed line of the power receiving cord substantially in phase and in substantially the same amount, the potential difference due to the electromagnetic noise between the ground line and the feed line is eliminated, A noise reduction method characterized by relatively reducing electromagnetic noise between a power supply line and the ground line. 5. A noise filter provided inside the device to which the power supply line of the power receiving cord is connected so that the electromagnetic noise radiated inside the device is superimposed on the power supply line of the power receiving cord from inside the device. While suppressing, the electromagnetic noise is superimposed on the ground wire of the power receiving cord via the ground wire inside the device by a disconnection portion formed near the connection end of the ground wire of the power receiving cord to the device. 5. The noise reduction method according to claim 4, wherein the electromagnetic noise superimposed on the ground line and the power supply line of the power receiving cord due to the electromagnetic noise radiated to the outside of the device is made substantially in-phase and substantially in the same amount. . 6. A noise filter provided inside the device to which the power supply line of the power receiving cord is connected, which suppresses electromagnetic noise radiated inside the device from being superimposed on the power supply line of the power receiving cord from inside the device. In addition, the electromagnetic noise is superimposed on the ground wire of the power receiving cord via the ground wire inside the device, and the disconnection formed near the connection end of the ground wire inside the device with respect to the ground wire of the power receiving cord 5. The noise according to claim 4, wherein the electromagnetic noise superimposed on a ground line and a power supply line of the power receiving cord due to the electromagnetic noise radiated to the outside of the device is made substantially in-phase and substantially in the same amount. Reduction method. 7. A power receiving cord comprising a grounding line and a power supply line, and supplying power supplied from the power receiving plug to a device connected via the power supply plug, wherein the ground wire near the power supply plug has a broken portion. A power receiving cord, characterized in that a power cord is formed. 8. The power receiving cord according to claim 7, wherein the disconnection portion is formed on the ground wire in the power supply plug.