JP2000244272A - Noise filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a noise reducing effect while making a whole system small. SOLUTION: The noise filter 13 arranged among power source lines 11a, 11b and 11c connecting a three-phase AC power source 11 to power electronic equipment 12 is constituted by providing inter-phase capacitors 14a, 14b and 14c for reducing a normal mode noise which mainly occurs from equipment 12, a filter circuit constituted by including a common mode choke coil, canceller ground capacitors 16a, 16b and 16c for working as a bypass to return noise generated from the equipment 12 to the grounded terminal 12a of the equipment 12 without passing through an AC power source 11 and a canceller 18 for permitting the common mode noise flowing in the respective phases of the power source lines to easily flow into the grounded terminal 12a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a noise filter using a common mode choke coil.

[0002]

2. Description of the Related Art For example, when a noise filter is provided at a power input portion of a power electronic device, conventionally,
A circuit configuration as shown in FIG. 12 is used. That is, in FIG. 12, the noise filter 3 provided between the three-phase AC power supply 1 and the power electronics device 2 includes power supply lines 1a, 1b,
1c, a common mode noise flows to the load side of the common mode choke coil 4 interposed in the ground capacitor 5
a, 5b, and 5c are connected, and interphase capacitors 6a, 6b, and 6c for reducing normal mode noise are connected to the power supply side of the common mode choke coil 4.

The power electronics device 2 includes a switching unit 7 and a load 8 driven by the switching unit 7. The common mode noise generated in the switching unit 7 is generated by the switching unit 7 and the metal of the power electronics device 2. Stray capacitance C with housing 9
1 or leaks to the ground through the stray capacitance C2 between the load 8 and the metal housing 9, and
An attempt is made to flow through a closed circuit of returning to the switching section 7 after turning around b and 1c. On the other hand, the common mode choke coil 4 shows a high impedance with respect to the common mode noise, and the common mode noise causes the power supply line 1a,
1b, 1c.

[0004] The impedance of the common mode choke coil 4 is mainly determined by the magnetic permeability of the core material and the number of turns of the coil. The greater the impedance, the greater the noise reduction effect. In this case, inexpensive ferrite is generally used as the core material of the common mode choke coil 4. However, in order to obtain a larger impedance, for example, a ferrite such as a nanocrystalline soft magnetic material is used. In some cases, a material having high magnetic permeability is used.

[0005] The grounding capacitors 5a, 5b and 5c are
It functions as a bypass for flowing the common mode noise leaked from the switching unit 7 to the ground terminal 2a of the power electronic device 2 without passing through the power supply 1. Similarly, the inter-phase capacitors 6a, 6b, 6c function as a bypass for passing normal mode noise to the ground terminal 2a of the power electronic device 2 without passing through the power supply 1.

[0006]

By the way, when a common ferrite is used as the core material of the common mode choke coil 4 constituting the noise filter 3, the cost can be reduced, but on the other hand, the transmission efficiency is reduced. There are circumstances where the magnetic susceptibility is lower than, for example, a nanocrystalline soft magnetic material. Therefore, when the impedance of the common mode choke coil 4 is set to a large value in order to improve the noise reduction effect, a configuration in which the number of coil turns is increased must be adopted. There is a problem that the enlargement cannot be avoided.

Further, in the above configuration, the stray capacitance between the windings increases as the number of coil turns increases.
With respect to noise having a frequency of several MHz or more, the impedance of the common mode choke coil 4 is greatly reduced, which causes a problem that the performance as a noise filter is reduced. On the other hand, in order to reduce the number of coil turns and reduce the size of the common mode choke coil 4, measures such as using a core material having high magnetic permeability (for example, the nanocrystalline soft magnetic material) have been taken.
In general, such a material is considerably higher in cost than ferrite, and therefore causes an increase in the cost of the noise filter 3 as a whole.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a noise filter which can improve the noise reduction effect while reducing the overall size.

[0009]

According to one aspect of the present invention, there is provided a noise filter interposed in a power supply line connecting a power supply and an electric device.
A filter circuit including a common mode choke coil, a noise absorbing capacitor connected between the power supply lines to reduce normal mode noise,
A canceller ground capacitor provided so as to electrically connect the power supply line to a ground terminal of the electric device; and a noise component interposed in the power supply line and generated by the electric device for the canceller. And a canceller that is drawn into a ground terminal of the electric device through a ground capacitor.

In the noise filter configured as described above, the noise reduction effect by the canceller is added to the noise reduction effect by the filter circuit and the noise absorbing capacitor, so that the noise can be more effectively reduced. Become. Also, the inductance of the inductance element constituting the filter circuit can be reduced, and the filter circuit can be significantly reduced in size as compared with a conventional general filter circuit, and the capacitance of the grounding capacitor for the canceller can be reduced. Since it can be downsized, it can be downsized as a whole even with the canceller added.

In this case, as in the second aspect of the present invention,
The canceller includes an annular magnetic core, and a grounding line for connecting between a canceller grounding capacitor and a grounding terminal of an electric device and the power supply line are inserted into the magnetic core at a time. Each line can be wound so that the turn ratio is 1: 1.

According to this configuration, the common mode noise flowing through the power supply line generates an AC magnetic flux in the magnetic core of the canceller, and the common line noise is applied to the ground line in synchronization with the above-described magnetic flux change. An electromotive force is generated which causes a current to flow in a direction opposite to the direction in which the mode noise flows. For this reason, the common mode noise generated from the electric device flows through the canceler grounding capacitor to the ground terminal of the electric device again, whereby the reduction of the common mode noise is realized. In this case, it is only necessary to provide a magnetic core in order to obtain the function of the canceller. Therefore, it is possible to suppress an increase in the manufacturing cost. Can be further reduced in size.

According to a third aspect of the present invention, the canceller includes a plurality of annular magnetic cores, and a grounding capacitor for the canceller and a ground terminal of an electric device are connected to each magnetic core. Of the ground line and the power supply line to be inserted may be inserted or wound so that the turns ratio is 1: 1. According to this configuration, a current is generated in each of the ground lines inserted or wound around each magnetic core so as to cancel the common mode noise flowing through each phase of the corresponding power supply line, and at the same time, A current that cancels the normal mode noise of each phase is also generated. As described above, the effect of reducing the normal mode noise that is not limited to the common mode noise is exerted. As a result, the capacitance of the noise absorbing capacitor provided for the purpose of reducing the normal mode noise can be reduced. Miniaturization can be realized. In addition, since the number of wires passing through each magnetic core is reduced, the size of each magnetic core can be reduced, and the overall size can be further reduced.

[0014] According to a fourth aspect of the present invention, the filter circuit may be configured using one common mode choke coil having a ferrite core. According to this configuration, it is only necessary to use an inexpensive ferrite core in order to obtain the above-described noise reduction effect and the like, so that cost reduction can be realized.

According to a fifth aspect of the present invention, the filter circuit may be configured as a T-type filter in which two common mode choke coils each having a ferrite core and a ground capacitor are combined. According to this configuration, a greater noise reduction effect can be obtained as compared with the case where the filter circuit is configured by one common mode choke coil.

In this case, as in the sixth aspect of the present invention,
The grounding capacitor constituting the T-type filter may use a canceling grounding capacitor.
According to such a configuration, the number of components can be reduced, the manufacturing cost can be reduced, and the overall size can be further reduced.

According to a seventh aspect of the present invention, the filter circuit, the noise absorbing capacitor, the grounding capacitor for the canceller, and the canceller may be housed in a metal housing for electric equipment. According to this configuration, since the filter circuit or the like as the noise reduction unit is disposed closest to the noise generation source, the power supply line connecting the noise reduction unit and the noise generation source in the electric device is connected. The level of noise radiated into the space can be minimized.

As described in the eighth aspect of the present invention, the filter circuit, the noise absorbing capacitor, the grounding capacitor for the canceller, and the canceller may be housed in a metal case to be modularized. According to this configuration, since the noise radiated into the space from the wiring connecting the components for the noise filter can be shielded by the metal case, the radiation noise can be reduced in addition to the conduction noise flowing to the power supply. In addition, according to such a single module,
The entire occupied volume or occupied area can be reduced, and the noise reduction effect can be further increased by connecting the components with the shortest wiring. Further, since the whole is one part, there are advantages such as easy handling.

According to a ninth aspect of the present invention, the metal case may be filled with an insulating material made of a resin or a gel material. According to this configuration, since the components of the noise filter are fixed by the insulating material, the vibration resistance of the noise filter is improved.

In order to prevent the insulating material from contacting the filter circuit and the canceller, a cover for covering the filter circuit and the canceller may be provided. According to this configuration, since an air layer having a dielectric constant smaller than the insulating material is formed around the filter circuit and the canceller,
Since the stray capacitance relating to the filter circuit and the canceller is reduced, and the impedance of the filter circuit can be prevented from lowering, the noise reduction effect can be satisfactorily exhibited.

[0021]

(First Embodiment) A first embodiment of the present invention will be described below with reference to FIG.
In FIG. 1, a noise filter 13 for removing noise superimposed on power lines 11a, 11b, and 11c of the AC power supply 11 is provided between a three-phase AC power supply 11 and a power electronic device 12 that is an electric device. Have been. This noise filter 13 has the following configuration.

That is, in the noise filter 13, the AC power source 1 in the power supply lines 11a, 11b, 11c
The inter-phase capacitors 14a, 14 connected to the position on the first side
b and 14c (corresponding to the noise absorbing capacitor in the present invention) are provided mainly for reducing normal mode noise generated from the power electronic device 12. In addition, power supply lines 11a, 11b, 11c
The filter circuit 15 interposed at the position on the load side of the inter-phase capacitors 14a, 14b, and 14c includes a common mode choke coil for reducing common mode noise mainly leaking to the AC power supply 11 side. The order is determined according to the generated noise level. Specifically, for example, when the noise level is relatively low, a primary filter circuit including one common mode choke coil is used, and when the noise level is high, a plurality of sets of common mode choke coils are used. And a high-order filter circuit composed of a ground capacitor.

Further, in the noise filter 13, the grounding capacitors 16 a, 16 b, 16 c connected to the power supply lines 11 a, 11 b, 11 c on the load side of the filter circuit 15 are connected to the noise generated from the power electronics device 12. To the AC power supply 11
It functions as a bypass for returning to the ground terminal 12a of the power electronic device 12 without passing through. These canceler ground capacitors 16a, 16
b, 16c are power supply lines 11a, 1
1b and 11c, respectively, and the other end is connected to the terminal Qa of the canceller 18 via the ground line 17 in common.

The canceller 18 is connected to the power line 11
a, 11b, and 11c, connected to the position closest to the load 12, detects common mode noise flowing through each phase of the power supply lines 11a, 11b, and 11c, and outputs the common mode noise through the canceler grounding capacitors 16a, 16b, and 16c. In order to make it easier to flow into the ground terminal 12a of the electronic device 12, the terminal Qa connected to the ground line 17 and the terminal Qb connected to the ground terminal 12a
During which the electromotive force is generated.

On the other hand, the power electronics device 12
Includes a switching unit 19 and a load 20 driven by the switching unit 19, and common mode noise generated in the switching unit 19 causes a common mode noise between the switching unit 19 and the metal casing 21 of the power electronic device 12. It leaks to the ground through the stray capacitance C1 or the stray capacitance C2 between the load 20 and the metal housing 21.

The common mode noise leaking as described above is transmitted from the AC power supply 11 to the power supply lines 11a, 11b, 11
Although it is going to flow through a closed circuit of returning to the switching unit 19 after turning around c, it is configured to include the filter circuit 15 having the common mode choke coil exhibiting high impedance against the common mode noise and the canceller 18. The common mode noise is provided by the power supply lines 11a, 11b, 1
The situation flowing through 1c is effectively prevented.

According to the above configuration, the inter-phase capacitor 1
Since the noise reduction effect of the canceller 18 is added to the noise reduction effect of the filter circuits 15 due to the filter circuits 15a, 14b, and 14c, the noise reduction effect is improved as compared with a conventional general noise filter. Moreover,
In this case, the inductance of the common mode choke coil constituting the filter circuit 15 can be reduced, or the capacitance of the ground capacitor connected thereto can be reduced.
Can be significantly reduced in size as compared with a conventional general noise filter, so that the noise filter 13 can be easily reduced in size even when the canceller 18 is added.

In the first embodiment, the same effect can be obtained even if the inter-phase capacitors 14a, 14b and 14c are arranged between the filter circuit 15 and the canceller 18 or between the canceller 18 and the power electronic equipment 12. Can be played.

(Second Embodiment) FIG. 2 shows a second embodiment of the present invention, and only the portions different from the first embodiment will be described below. That is, in the second embodiment, in order to obtain the function of the canceller 18 in the first embodiment, a ring-shaped magnetic core 22 made of, for example, ferrite is provided. 11a, 11b, 11c and the ground line 17 are inserted together in the same phase, or the power supply lines 11a, 11b, 11c and the ground line 17 are wound several turns so that the turns ratio is 1: 1. It is configured to be connected to the ground terminal 12a of the power electronics device 12 (in the example of FIG. 2, the power supply lines 11a, 11a).
b, 11c and the ground line 17 are shown wound around the magnetic core 22). Thus, the function as a passive canceller is obtained in the magnetic core 22.

According to such a configuration, the power supply line 11
The common mode noise flowing through each of the phases a, 11b, and 11c generates an AC magnetic flux in the magnetic core 22, and the common mode noise is generated on the ground line 17 in synchronization with the magnetic flux change as described above. An electromotive force is generated which causes a current to flow in a direction opposite to the flowing direction. For this reason, the common mode noise generated from the power electronic device 12 passes through the ground capacitors 16a, 16b, and 16c, and returns to the ground terminal 1 of the power electronic device 12.
2a, thereby reducing the common mode noise. In this case, common mode noise in a frequency band of about 500 kHz to 5 MHz can be effectively reduced.

According to the above-described second embodiment, it is only necessary to provide the magnetic core 22 in order to obtain the function of the canceller. Therefore, it is possible to suppress an increase in manufacturing cost, and furthermore, the magnetic core 22 Since it is not necessary to provide many windings, it is possible to reduce the size of the noise filter 13 as a whole. Further, an inexpensive ferrite core can be used as the magnetic core 22, and in this case, further reduction in cost can be realized.

(Third Embodiment) FIG. 3 shows a third embodiment of the present invention, and only the portions different from the first embodiment will be described below. That is, in the third embodiment, in order to obtain the function of the canceller 18 in the first embodiment, three ring-shaped magnetic cores 23a, 23b and 23c made of, for example, ferrite are provided, and each magnetic core 2
3a, 23b, 23c, the power supply line 11 of each phase.
a, 11b, 11c and ground lines 17a, 17b, 17
c (the ground capacitors 16a, 1
6b and 16c), or each pair of the power supply lines 11a, 11b and 11c and the ground lines 17a and 17
b and 17c are wound several turns so that the turns ratio becomes 1: 1 (in the example of FIG.
1a, 11b, 11c and ground lines 17a, 17b,
17c are wound around the magnetic cores 23a, 23b, 23c, respectively). Thereby, the magnetic cores 23a, 23b, and 23c are configured to obtain a function as a passive canceller.

The noise filter 13 configured as described above
In the above, a current is applied to the ground lines 17a, 17b, 17c inserted or wound around the magnetic cores 23a, 23b, 23c so as to cancel the common mode noise flowing through each phase of the power supply lines 11a, 11b, 11c. At the same time, a current that cancels the normal mode noise of each phase is also generated. As described above, the effect of reducing the normal mode noise that is not limited to the common mode noise is exerted. As a result, the interphase capacitors 14a provided for the purpose of reducing the normal mode noise,
The capacitances of the noise filters 14b and 14c can be reduced, and the noise filter 13 can be further reduced in size. Further, since the number of wires passing through each of the magnetic cores 23a, 23b, 23c is reduced, the respective magnetic cores 23a, 23b,
23c can be reduced in size, and the noise filter 13
Can be further reduced in size.

(Fourth Embodiment) FIG. 4 shows a fourth embodiment of the present invention, which embodies the configuration of the second embodiment. Hereinafter, the different parts from the second embodiment will be described. I will explain only. In the fourth embodiment, the filter circuit 15 in the second embodiment is realized by a common mode choke coil 24 as shown in FIG. The common mode choke coil 24 uses ferrite as a core material, and its magnetic permeability is determined according to the frequency band of noise to be reduced.

According to the present embodiment having the above-described configuration, the simplest configuration in which only one common mode choke coil 24 is used in order to obtain the function of the filter circuit is sufficient. Since inexpensive ferrite is used as the core material of the first embodiment, the manufacturing cost of the noise filter 13 can be reduced. Furthermore, by reducing the number of turns of the common mode choke coil 24, it is possible to suppress a decrease in impedance with respect to noise of several MHz or more, which has been a problem due to the effect of stray capacitance between the windings. The noise reduction effect of the mode choke coil 24 can be improved. Note that, instead of the magnetic core 22 in the present embodiment, three magnetic cores 23a, 23b, and 23c as described in the third embodiment may be provided.

(Fifth Embodiment) FIG. 5 shows a fifth embodiment of the present invention in which the fourth embodiment is modified, and only different portions will be described below. The fifth embodiment is characterized in that a T-type LC filter 25 is provided instead of the common mode choke coil 24 in the fourth embodiment. The LC filter 25 includes two common mode choke coils 26 and 27 interposed in series in the power supply lines 11a, 11b, and 11c, and a ground capacitor 28a having one end connected to a common connection point of the choke coils 26 and 27. The other end of each of the ground capacitors 28a, 28b, 28c is connected to a ground terminal 12a of the power electronic device 12 via a ground line 29. In this case, ferrite is used as the core material of the common mode choke coils 26 and 27. Among them, the common mode choke coil 26 on the AC power supply 11 side is used.
Ferrite core for power electronics equipment 1
The ferrite core of the other common mode choke coil 27 on the two sides is configured to have the same or higher magnetic permeability. The number of turns of the common mode choke coil 27 is set to seven or less.

According to the fifth embodiment having such a configuration, the common mode choke coil 2 disposed on the AC power supply 11 side
6 effectively reduces noise particularly at several MHz or less, and conversely, the common mode choke coil 27 arranged on the power electronics device 12 side effectively reduces noise at several MHz or more. Yes, and consequently,
As compared with the configuration in which one common mode choke coil 24 is provided as in the fourth embodiment, a greater noise reduction effect can be obtained.

(Sixth Embodiment) FIG. 6 shows a sixth embodiment of the present invention in which the fifth embodiment is modified, and only different portions will be described below. In the sixth embodiment, the ground capacitor 16 in the fifth embodiment is used.
After removing the a, 16b and 16c and the ground line 17, the magnetic capacitors 22a and 28 in the LC filter 25 are connected to the magnetic core 22 for forming the canceller.
b, 28c and the power line 1
1a, 11b, and 11c are inserted together in the same phase, or the power supply lines 11a, 11b, 11c, and the ground line 29 are wound several turns so that the turns ratio is 1: 1. The power supply lines 11a, 11b, 11c and the ground line 29 are wound around the magnetic core 22 in the example of FIG.

In the sixth embodiment having such a configuration, a good noise reduction effect can be obtained. In particular, in this embodiment, one set of the ground capacitors 28a is used as the ground capacitor constituting the noise filter 13. , 2
Since it is sufficient to provide only 8b and 28c, the number of parts can be reduced as compared with the configuration of the fifth embodiment, the manufacturing cost can be reduced, and further downsizing can be realized.

In the sixth embodiment, as shown in FIG. 7, one common mode choke coil 27 of the T-type LC filter 25 is disposed between the magnetic core 22 and the power electronic device 12. A good noise reduction effect can be obtained in the same manner as described above.

(Seventh Embodiment) FIG. 8 shows a seventh embodiment of the present invention, which will be described below.
Here, an example using the noise filter 13 (see FIG. 6) in the sixth embodiment will be described, but it goes without saying that the noise filter 13 in another embodiment may be used.

That is, in the seventh embodiment, the noise filter 13 is housed in the metal housing 21 of the power electronic device 12, and in this case, the noise filter 13 is a switching unit which is a noise generating source. It is located very close to 19. Also, a grounding capacitor 2
A ground line 29 extending from 8a, 28b, 28c is electrically connected to the externally grounded metal housing 21. At this time, the ground line 29 is configured such that the length of the ground line 29 is minimized. Is done.

In the seventh embodiment configured as described above, since the noise filter 13 is arranged closest to the noise source, the power supply line 11a connecting between the noise filter 13 and the switching unit 19, 1
The level of noise radiated from 1b and 11c into the space can be suppressed as much as possible. Also, the grounding capacitor 28
By minimizing the ground line 29 extending from a, 28b, 28c, the influence of the inductance of the wiring is almost eliminated. Therefore, common mode noise easily flows to the ground terminal 12a of the power electronic device 12 through the ground capacitors 28a, 28b, and 28c, and hardly leaks to the AC power supply 11, so that the noise reduction effect is improved. Become. Further, by appropriately arranging the components of the noise filter 13 in the power electronics device 12, the power electronics device 12 and the noise filter 13 are compared with a configuration in which the power electronics device 12 and the noise filter 13 are separately provided. 13 can be significantly reduced in size as a whole.

(Eighth Embodiment) FIG. 9 shows an eighth embodiment of the present invention, which will be described below.
FIG. 9 shows, for example, a cross-sectional structure of the noise filter 13 (see FIG. 4) in the fourth embodiment. The noise filter 13 mounted on the printed wiring board 30 is stored in a metal case 31 in a sealed state. Terminal blocks 32 and 33 electrically connected to the printed wiring board 30 are provided on the outer surface of the metal case 31. Note that one terminal block 32 is for connecting the power supply side of the noise filter 13 to the AC power supply 11 via the power supply lines 11a, 11b, 11c.
Is the load side of the noise filter 13 and the power line 11
a, 11b, 11c and a ground line 17 for connection to the power electronics device 12.

According to the eighth embodiment configured as described above,
Since the noise radiated into the space from the wiring connecting the components of the noise filter 13 can be shielded by the metal case 31,
In addition to the conduction noise flowing through the AC power supply 11, radiation noise can also be reduced. In addition, in accordance with such a modularization, the occupied volume or occupied area of the noise filter 13 can be reduced by optimally arranging the components constituting the noise filter 13, and the shortest wiring between the components can be achieved. By connecting them, the noise reduction effect is further improved. Further, since the noise filter 13 itself is a single component, it is easy to handle, and when the noise filter 13 is incorporated in the power electronic device 12, there is an advantage that the number of components and the number of manufacturing steps are reduced.

When the noise filter 13 is housed in the power electronic device 12 surrounded by the metal casing 21 as in the seventh embodiment, the metal casing 21 is designed to shield radiation noise. Therefore, a case made of a material other than metal may be used instead of the metal case 31.

(Ninth Embodiment) FIG. 10 shows a ninth embodiment of the present invention in which the above-described eighth embodiment is modified, and only different portions will be described below. That is, in the ninth embodiment, an insulating material 3 such as a resin material or a silicone gel (corresponding to a gel material in the present invention) is placed in a metal case 31 containing a noise filter 13.
4 is filled. According to such a configuration, the noise filter 13 is covered with the insulating material 34, that is, the components constituting the noise filter 13 are fixed with the insulating material 34, so that the noise filter 13 is resistant to noise. Vibration is improved. Insulating material 3
If a material having excellent thermal conductivity is used for 4, the heat radiation of each component can be improved.

(Tenth Embodiment) FIG. 11 shows a tenth embodiment of the present invention in which the above-mentioned ninth embodiment is modified, and only different portions will be described below.
That is, in the tenth embodiment, in the noise filter 13 covered with the insulating material 34, the common mode choke coil 24 and the magnetic core 22 constituting the passive canceller are covered with the covers 35 and 36, respectively. Therefore, the insulating material 34 does not penetrate around them. According to this configuration, around the common mode choke coil 24 and the magnetic core 22,
Since an air layer having a dielectric constant smaller than that of the insulating material 34 is formed, the stray capacitance between the windings of the common mode choke coil 24 and the stray capacitance of the winding wound around the magnetic core 22 are reduced. For this reason, it is possible to prevent a decrease in the impedance of the common mode choke coil 24 and the impedance of the passive canceller formed by the magnetic core 22, and it is possible to effectively exhibit a noise reduction effect.

(Other Embodiments) Although the noise filter interposed in the power line of the three-phase AC power supply has been described as an example, the present invention is also applicable to a noise filter interposed in the power line of a single-phase AC power supply. is there.

[0050]

As is apparent from the above description, the following effects can be obtained according to the present invention. According to the noise filter of the first aspect, the noise reduction effect of the canceller is added to the noise reduction effect of the noise absorbing capacitor and the filter circuit.
Noise can be reduced more effectively. Also,
The amount of noise reduction borne by the filter circuit is reduced, and the overall size can be reduced as compared with the case where the filter circuit is used alone.

According to the noise filter of the second aspect,
Since it is only necessary to provide the magnetic core in order to obtain the function of the canceller, it is possible to suppress an increase in the manufacturing cost and to realize a further reduction in size as a whole.

According to the noise filter of the third aspect,
Since the effect of reducing normal mode noise, which is more than just common mode noise, works, the capacitance of the noise absorbing capacitor provided to reduce normal mode noise can be reduced, further reducing the overall size. As a result, the number of wires passing through each magnetic core is reduced, so that the size of each magnetic core can be reduced, and the overall size can be further reduced.

According to the noise filter of the fourth aspect,
It is only necessary to use one common mode choke coil having an inexpensive ferrite core to obtain a noise reduction effect and the like, so that cost reduction can be realized.

According to the noise filter of the fifth aspect,
Since the filter circuit is configured as a T-type filter in which two common mode choke coils and a grounding capacitor are combined, a greater noise reduction than when the filter circuit is configured with one common mode choke coil The effect will be obtained.

According to the noise filter of the sixth aspect,
Since the grounding capacitor constituting the T-type filter and the grounding capacitor for the canceller can be shared, the number of parts can be reduced, the manufacturing cost can be reduced, and the overall size can be further reduced.

According to the noise filter of the seventh aspect,
Since a filter circuit or the like, which is noise reduction means, is arranged closest to the noise generation source, the noise is radiated to the space from a power supply line connecting the noise reduction means and the noise generation source in the electric device. The noise level can be suppressed as much as possible.

According to the noise filter of the eighth aspect,
Since the noise radiated into the space from the wiring connecting the components for the noise filter can be shielded by the metal case,
In addition to conduction noise flowing through the power supply, radiation noise can be reduced, and as the whole is made into one module, the total occupied volume or area can be reduced. By connecting them with the shortest wiring, the noise reduction effect is further improved.

According to the noise filter of the ninth aspect,
Since the components of the noise filter are fixed with the insulating material, the vibration resistance of the noise filter is improved.

According to the noise filter of the tenth aspect, an air layer having a dielectric constant smaller than the insulating material is formed around the filter circuit and the canceller.
The stray capacitances related to the filter circuit and the canceller are reduced, so that their impedance can be prevented from lowering. As a result, the noise reduction effect can be favorably exhibited.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating a noise filter and a peripheral circuit according to a first embodiment of the present invention;

FIG. 2 is a view corresponding to FIG. 1 showing a second embodiment of the present invention.

FIG. 3 is a view corresponding to FIG. 1, showing a third embodiment of the present invention;

FIG. 4 is a view corresponding to FIG. 1, showing a fourth embodiment of the present invention;

FIG. 5 is a view corresponding to FIG. 1, showing a fifth embodiment of the present invention.

FIG. 6 is a view corresponding to FIG. 1, showing a sixth embodiment of the present invention;

FIG. 7 shows an example of a configuration in which the sixth embodiment is partially modified.
Equivalent figure

FIG. 8 is a view corresponding to FIG. 1, showing a seventh embodiment of the present invention.

FIG. 9 is a sectional view of a noise filter according to an eighth embodiment of the present invention.

FIG. 10 is a view corresponding to FIG. 9 showing a ninth embodiment of the present invention.

FIG. 11 is a view corresponding to FIG. 9 showing a tenth embodiment of the present invention;

FIG. 12 is a diagram corresponding to FIG. 1 showing a conventional example.

[Explanation of symbols]

11 is a three-phase AC power supply, 11a, 11b and 11c are power supply lines, 12 is power electronics equipment (electric equipment), 13 is a noise filter, 14 is an interphase capacitor (noise absorbing capacitor), 15 is a filter circuit,
6a, 16b, 16c are grounding capacitors for cancellers,
17 is a ground line, 18 is a canceller, 19 is a switching unit, 20 is a load, 21 is a metal housing, 22, 23a,
23b and 23c are magnetic cores, 24 is a common mode choke coil, 25 is an LC filter, 26 and 27 are common mode choke coils, 28a, 28b and 28c are ground capacitors, 29 is a ground line, 31 is a metal case,
4 is an insulating material, 35 and 36 are covers.

Continued on the front page (72) Inventor: Wataru Ito 2121, Nao, Nao, Asahimachi, Mie-gun, Mie Prefecture Inside the Toshiba Mie Plant (72) Inventor: Tomohiko Tanimoto 2121, Ozai, Oaza, Asahi-machi, Mie-gun, Mie Co., Ltd. Inside the Toshiba Mie Plant (72) Inventor Takayuki Ishii 2121 Nagoya, Asahi-machi, Mie-gun, Mie Prefecture F-term in the Toshiba Mie Plant (reference) 5J024 AA01 BA03 DA01 DA26 DA31 DAEA8

Claims (10)

[Claims] 1. A noise filter interposed in a power supply line connecting a power supply and an electric device, a filter circuit including a common mode choke coil, and the power supply line for reducing normal mode noise. A noise absorbing capacitor connected between the power supply line and a grounding capacitor for canceller provided to electrically connect between the power supply line and a ground terminal of the electric device; A noise filter comprising: a canceller that draws a noise component generated in an electric device to a ground terminal of the electric device through the canceler ground capacitor. 2. The canceller includes an annular magnetic core, and a grounding line for connecting a grounding capacitor for the canceller and a grounding terminal of an electric device and the power supply line are collectively formed on the magnetic core. 2. The noise filter according to claim 1, wherein the noise filter is configured to be inserted or wound so that a turn ratio of each line is 1: 1 in a state. 3. The canceller includes a plurality of annular magnetic cores, and each of the magnetic cores includes a grounding line for connecting a grounding capacitor for the canceller and a grounding terminal of an electric device, and a power supply line. 2. The noise filter according to claim 1, wherein said noise filters are configured so that said in-phase ones are inserted or wound so that the turns ratio is 1: 1. 4. The noise filter according to claim 1, wherein the filter circuit is configured using one common mode choke coil having a ferrite core. 5. The filter circuit according to claim 1, wherein the filter circuit is configured as a T-type filter combining two common mode choke coils having a ferrite core and a grounding capacitor. Noise filter. 6. The noise filter according to claim 5, wherein the grounding capacitor constituting the T-type filter uses a canceling grounding capacitor. 7. The device according to claim 1, wherein the filter circuit, the noise absorbing capacitor, the grounding capacitor for the canceller, and the canceller are housed in a metal housing for an electric device. Noise filter. 8. The noise filter according to claim 1, wherein the filter circuit, the noise absorbing capacitor, the grounding capacitor for the canceller, and the canceller are housed in a metal case to form a module. 9. The noise filter according to claim 8, wherein an insulating material made of resin or gel material is filled in the metal case. 10. The noise filter according to claim 9, wherein a cover for covering the filter circuit and the canceller is provided to prevent the insulating material from contacting the filter circuit and the canceller.