JP2004288882A - Noise filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a noise filter which can improve magnetic saturation strength and can adequately attain attenuation characteristic thereof. <P>SOLUTION: The noise filter is provided with a plurality of coils L1, L2, and L3 which are wound to the common magnetic paths connected to different electric paths. In this noise filter, a first magnetic flux circulating magnetic path M1, and a second magnetic flux circulating magnetic path M2 provided around the first magnetic flux circulating magnetic path M1, are provided as the common magnetic paths. At the same time, the first magnetic flux circulating magnetic path M1 is formed of a magnetic material of silicone steel plate, dust core, permalloy, Ni-Zn ferrite or the like having the magnetic saturation strength which is larger than that of the second magnetic flux circulating magnetic path M2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a noise filter, and more particularly to a noise suppression filter using a composite core material.
[0002]
[Prior art]
In a conventional noise filter, two ferrite core materials having different characteristics are collectively wound to form a common mode coil in order to broaden the filter characteristics (for example, see Patent Document 1).
In such a configuration, when a large common mode current is generated, the ferrite core is likely to be magnetically saturated, so that there is a problem that the core becomes large in order to secure a required filter attenuation factor.
There is no description about the saturation of the core due to the common mode current, and the configuration is not configured to avoid the saturation.
[0003]
Further, in the conventional noise filter, a material (for example, a silicon steel plate) having a low magnetic permeability at the inverter carrier frequency is used to avoid magnetic saturation. In particular, this configuration is used in a common / normal dual-purpose coil using an EI core attached to a rectified DC section of an inverter device.
Since such a material has low magnetic permeability, there is a problem that the core must be large and the number of turns needs to be increased in order to secure a required filter attenuation rate.
[0004]
[Patent Document 1]
JP-A-3-62607
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to provide a noise filter capable of improving magnetic saturation proof strength and appropriately securing filter attenuation characteristics.
[0006]
[Means for Solving the Problems]
In the noise filter according to the present invention, the first magnetic flux circulating magnetic path and the first magnetic flux circulating magnetic path are arranged as a common magnetic path around which the plurality of coil elements of the choke coil are wound. A second magnetic flux circulating magnetic path is provided, and the first magnetic flux circulating magnetic path is made of a magnetic material having a higher magnetic saturation strength than the second magnetic flux circulating magnetic path.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
First Embodiment A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing an overall configuration according to the first embodiment. FIG. 2 is a schematic diagram showing a configuration of a core material and a coil according to the first embodiment. FIG. 3 is an explanatory diagram showing a characteristic comparison with the conventional technology in the first embodiment.
[0008]
In the noise filter shown in FIG. 1, capacitors C1, C2, and C3 are connected between the respective phase lines of the system power supply terminals 1, 2, and 3 connected to the system power supply in the three-phase circuit system.
Capacitors C4, C5, and C6 are connected between the respective phase lines of the inverter device side terminals 4, 5, and 6 connected to the inverter device.
Capacitors C7, C8, C9 are connected between the ground terminal 7 and the inverter device side terminals 4, 5, 6.
A common mode choke coil 8 is connected between the system power supply terminals 1, 2, 3 and the inverter device terminals 4, 5, 6.
[0009]
2, a coil element L1 constituting the common mode choke coil 8 is connected between the system power supply side terminal 1 and the inverter device side terminal 4.
The coil element L2 constituting the common mode choke coil 8 is connected between the system power supply side terminal 2 and the inverter device side terminal 5.
The coil element L3 constituting the common mode choke coil 8 is connected between the system power supply side terminal 3 and the inverter device side terminal 6.
The coil elements L1, L2, L3 are respectively wound around the first and second magnetic flux circulating magnetic paths M1, M2 such that the first and second magnetic circulating magnetic paths M1, M2 are used as a common magnetic path. You.
[0010]
These coil elements L1, L2, L3 are connected to the respective phase electric circuits in the three-phase circuit system, and the first and second coil elements L1, L2, L3 operate so that the first and second magnetic flux circulating magnetic paths M1, M2 operate as a common magnetic path. The choke coil 8, which is wound around the two magnetic flux circulating magnetic paths M1 and M2 and includes coil elements L1, L2 and L3, functions as a common mode choke coil.
[0011]
The first magnetic flux circulating magnetic path M <b> 1 is formed of a core material 9 disposed inside and having a high resistance to magnetic saturation. Examples of the material of the core material 9 include a silicon steel plate, a dust core, permalloy, and Ni—Zn ferrite.
The second magnetic flux circulating magnetic path M2 is formed of a core material 10 arranged on the outside and having low resistance to magnetic saturation. Examples of the material of the core material 10 include iron-based amorphous material and Mn-Zn ferrite.
[0012]
With this configuration, the length of the magnetic path in the second magnetic flux circulating magnetic path M2 formed of the outer core material 10 having a low magnetic saturation proof strength is increased, and saturation is unlikely.
Although the magnetic path length of the first magnetic flux circulating magnetic path M1 as the inner core is short, since it is made of the core material 9 having a large magnetic saturation strength, the first magnetic flux circulating magnetic path M1 is hardly saturated due to its characteristics, and the design has a margin.
As described above, a common mode coil having a large magnetic saturation proof strength and wide band characteristics can be realized.
[0013]
Here, a composite core material is used as a common magnetic path of a common mode choke coil that has a plurality of coil elements connected to different electric circuits such as each phase electric circuit in a three-phase circuit system and operates in a so-called common mode. FIG. 3 will be described in detail for the operation and effect in this case.
FIG. 3A is a configuration diagram showing a single core as a comparison target. FIG. 3B is a configuration diagram showing a composite core according to the present invention in which a single core is compared. FIG. 3C is an explanatory diagram showing a comparison of calculation formulas relating to the generated magnetic flux density and impedance in the single core and the composite core. FIG. 3D is an explanatory diagram showing a comparison of characteristics related to generated magnetic flux density and impedance in a single core and a composite core.
3, the inner core of the composite core corresponds to the core material 9 constituting the first magnetic flux circulating magnetic path M1 in FIG. 2, and the outer core of the composite core corresponds to the second magnetic flux circulating magnetic path M2 in FIG. Corresponds to the core material 10.
[0014]
The generated magnetic flux density and impedance in the single core and the composite core shown in FIGS. 3A and 3B are represented by the equations shown in FIG. 3C.
For example, let's compare the characteristics with the following parameters.
a = 2 cm, b = 5 cm, c = 3.5 cm
N1 = 5 turns, N2 = 9 turns μ1 (ferrite material) = 5000 × μ ₀
μ2 (silicon steel plate material) = 100 × μ ₀
ω = 2π × 150kHz
The comparison result is shown in the column of the characteristic comparison A in FIG. From this comparison, the characteristics of the single core and the composite core hardly change.
[0015]
However, the actual composite core uses a silicon steel plate or the like for the inner core, so that the R component, that is, the resistance component of the impedance of the choke coil by the composite core is 4 to 10 times that of a single core of about 10Ω or less. Reach a degree.
Since the common mode current in the common mode choke coil is determined by the resonance part, that is, the place where the reactance component is as close to zero as possible, the common mode current decreases almost in inverse proportion to the R component impedance, and when a single core (ferrite) is used. Is about 1/4 of the current value. When the characteristics are compared again in consideration of this effect, the results are as shown in the column of the characteristic comparison B in FIG.
Here, in the composite core, assuming that the current value is reduced to 1/4, the number of turns can be tripled in consideration of the saturation value, so that I = 0.25 A and N2 = 27 turns.
[0016]
As described above, in the common mode choke coil using the composite core, a choke coil in which the generated magnetic flux density is suppressed and the impedance (attenuation amount) is large can be realized.
[0017]
According to the first embodiment of the present invention, a common mode choke including a plurality of coil elements L1, L2, and L3 connected to respective phase paths and wound on a common magnetic path in a multiphase circuit such as a three-phase circuit. In the one provided with the coil 8, as the common magnetic path, a first magnetic flux circulating magnetic path M1 made of an annular core material 9 and the outer peripheral side surrounding the first magnetic flux circulating magnetic path M1 are provided. A second magnetic flux circulating magnetic path which is provided concentrically with the first magnetic flux circulating magnetic path M1 and has an annular core material 10 which circulates the magnetic flux in parallel with the magnetic flux circulating in the first magnetic flux circulating magnetic path M1. M2, and the outer diameter / inner diameter ratio of the first magnetic flux circulating magnetic path M1 composed of the annular core material 9 and the second magnetic flux circulating magnetic path M2 composed of the annular core material 10 is determined. And different from each other and made of the annular core material 9 Since the first magnetic flux circulating magnetic path M1 is made of a magnetic material having a higher magnetic saturation proof strength than the second magnetic flux circulating magnetic path M2 made of the annular core material 10, the magnetic saturation proof strength is improved and the filter attenuation is appropriately performed. It is possible to obtain a noise filter for a polyphase circuit using an annular composite magnetic path that can secure characteristics.
[0018]
Embodiment 2 FIG.
Embodiment 2 of the present invention will be described with reference to FIG. FIG. 4 is a schematic diagram showing a configuration of a core material and a coil according to the second embodiment.
In the second embodiment, the configuration other than the specific configuration described here has the same configuration content as the configuration in the first embodiment described above, and has the same operation. In the drawings, the same reference numerals indicate the same or corresponding parts.
[0019]
In FIG. 4, the first magnetic flux circulating magnetic path M <b> 1 is formed of a core member 11 disposed inside and having a high resistance to magnetic saturation. Examples of the material of the core material 11 include a silicon steel plate, a dust core, permalloy, and Ni—Zn ferrite.
The second magnetic flux circulating magnetic path M <b> 2 is formed of a core material 12 disposed on the outside and having low resistance to magnetic saturation, and has a gap g. Examples of the material of the core material 12 include iron-based amorphous material and Mn-Zn ferrite.
[0020]
With this configuration, by providing the gap g, the magnetic saturation proof strength of the second magnetic flux circulating magnetic path M2 formed of the outer core material 12 having a low magnetic saturation proof strength is increased, and the number of turns is increased. In addition, it is possible to realize a common mode coil in which magnetic saturation does not occur while securing a required filter attenuation rate.
[0021]
According to the second embodiment of the present invention, in the configuration of the first embodiment, by providing gap g in second magnetic flux circulating magnetic path M2, the magnetic saturation proof stress of second magnetic flux circulating magnetic path M2 is increased. In other words, a noise filter that can suppress the occurrence of magnetic saturation while securing a necessary filter attenuation rate due to an increase in the number of windings can be realized.
[0022]
Embodiment 3 FIG.
Third Embodiment A third embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a block diagram showing an overall configuration according to the third embodiment. FIG. 6 is a schematic diagram showing a configuration of a core material and a coil according to the third embodiment.
In the third embodiment, the configuration other than the specific configuration described here has the same configuration contents as the configuration in the first embodiment described above, and has the same operation. In the drawings, the same reference numerals indicate the same or corresponding parts.
[0023]
The noise filter shown in FIG. 5 is attached to the rectified DC section of the inverter device.
A capacitor C10 is connected between the rectifier-side positive terminal 13 and the rectifier-side negative terminal 14 that are connected to the rectifier output terminal of the inverter device.
A capacitor C11 is connected between the pole lines of the inverter terminals 15, 16 connected to the input terminals of the inverter device.
Capacitors C12 and C13 are connected between the ground terminal 17 and the inverter terminals 15 and 16.
A common / normal mode choke coil 18 is connected between the rectifier terminals 13 and 14 and the inverter terminals 15 and 16.
[0024]
In FIG. 6, a coil element L <b> 11 constituting the common / normal mode choke coil 18 is connected between the rectifier-side positive terminal 13 and the inverter terminal 15.
The coil element L12 constituting the common / normal mode choke coil 18 is connected between the rectifier side negative terminal 14 and the inverter terminal 16.
The coil elements L11 and L12 are wound around the first and second magnetic flux circulating magnetic paths M11 and M12, respectively, so that the first and second magnetic circulating magnetic paths M11 and M12 are used as a common magnetic path.
[0025]
These coil elements L11 and L12 are connected to respective pole circuits in a DC circuit such as a rectified DC section of the inverter device, and operate using the first and second magnetic flux circulating magnetic paths M11 and M12 as a common magnetic path. As described above, the choke coil 18 wound around the first and second magnetic flux circulating magnetic paths M11 and M12 and including the coil elements L11 and L12 functions as a common mode choke coil.
The coil elements L11 and L12 also individually operate by circulating the magnetic flux independently by the magnetic flux passing through the bridging magnetic path m having the gap gm, that is, also performing an operation as a so-called normal mode. The choke coil 18 has a function as a common / normal mode combined choke coil.
[0026]
The first magnetic flux circulating magnetic path M11 is configured in a frame shape as an EI core with a core material 19 disposed inside and having a high resistance to magnetic saturation. Examples of the material of the core material 19 include a silicon steel plate, a dust core, permalloy, and Ni—Zn ferrite. The first magnetic flux circulating magnetic path M11 made of the core member 19 is provided with a bridging magnetic path m that magnetically bridges the inside of the intermediate portion of the magnetic flux circulating magnetic path M11 via the gap gm.
The second magnetic flux circulating magnetic path M12 is formed of the core member 20 disposed on the outside and having low resistance to magnetic saturation. Examples of the material of the core material 20 include iron-based amorphous and ferrite.
[0027]
With this configuration, it is possible to realize a wider filter characteristic, a smaller coil, and a reduced number of turns, as compared with a case where the core is formed of the inner material alone.
[0028]
According to the third embodiment of the present invention, a common circuit including a plurality of coil elements L11 and L12 connected to respective pole circuits and wound around a common magnetic path in a DC circuit such as a rectified DC section of an inverter device. In the one provided with the choke coil 18 for / normal mode, as the common magnetic path, a first magnetic flux circulating magnetic path M11 composed of an E-I core constituted by a frame-shaped core material 19; The magnetic flux circulating magnetic path M11 is surrounded and arranged coaxially on the same central axis as the first magnetic flux circulating magnetic path M11 on the outer peripheral side thereof, in parallel with the magnetic flux circulating through the first magnetic flux circulating magnetic path M11. A second magnetic flux circulating magnetic path M12 made of a frame-shaped core material 20 for circulating magnetic flux is provided, and a first magnetic flux circulating magnetic path M11 made of the frame-shaped core material 19 is connected to the frame-shaped core material 20. Since the magnetic material is made of a magnetic material having a higher magnetic saturation strength than the second magnetic flux circulating magnetic path M12, the magnetic saturation strength is improved, and the filter attenuation characteristics can be appropriately secured. A circuit noise filter can be obtained.
[0029]
Embodiment 4 FIG.
Embodiment 4 of the present invention will be described with reference to FIG. FIG. 7 is a schematic diagram showing a configuration of a core material and a coil according to the fourth embodiment.
In the fourth embodiment, the configuration other than the specific configuration described here has the same configuration contents as the configuration in the third embodiment described above, and has the same operation. In the drawings, the same reference numerals indicate the same or corresponding parts.
[0030]
FIG. 7 shows a configuration of the common / normal mode combined choke coil shown in FIG. 6, in which a gap g is provided in the outer core material 20 having a low saturation strength and constituting the magnetic flux circulating magnetic path M12.
With such a configuration, the saturation strength of the magnetic flux circulating magnetic path M12 formed of the outer core material 20 having a low saturation strength is improved, and the required filter attenuation rate is ensured, and the size is small and magnetic saturation does not occur. A common mode coil can be realized.
[0031]
According to the fourth embodiment of the present invention, in the configuration of the third embodiment, by providing gap g in second magnetic flux circulating magnetic path M12, the magnetic saturation proof strength of second magnetic flux circulating magnetic path M12 is improved. In addition, it is possible to realize a noise filter that is small and can suppress the occurrence of magnetic saturation while securing a required filter attenuation rate.
[0032]
As described above, in the noise filter according to the embodiment of the present invention, a core material having a high saturation strength (such as a silicon steel sheet, a dust core, a permalloy, or a Ni—Zn ferrite) is disposed inside, and a core material having a low saturation strength ( Amorphous, Mn-Zn ferrite, etc.) are disposed outside, and they are wound together to form a common mode coil.
With this configuration, the magnetic path length in the outer core material having a low saturation strength becomes long, and the core material is hardly saturated. Although the magnetic path length of the inner core is short, it is a core material having a large saturation proof strength. Thus, a common mode coil having a large saturation strength and a wide band characteristic can be realized.
Further, in order to improve the saturation strength of the entire coil, a gap is provided in the outer core material having a low saturation strength to form a common mode coil. By configuring in this way, the saturation resistance of the outer core material with low saturation resistance is increased, and a common mode coil that does not cause magnetic saturation while securing the required filter attenuation factor due to an increase in the number of windings is realized. it can.
[0033]
【The invention's effect】
According to the present invention, it is possible to obtain a noise filter capable of improving magnetic saturation proof strength and appropriately securing filter attenuation characteristics.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration according to a first embodiment of the present invention.
FIG. 2 is a schematic diagram showing a configuration of a core material and a coil according to the first embodiment of the present invention.
FIG. 3 is an explanatory diagram showing a characteristic comparison with a conventional technology according to the first embodiment of the present invention.
FIG. 4 is a schematic diagram showing a configuration of a core material and a coil according to a second embodiment of the present invention.
FIG. 5 is a block diagram showing an overall configuration according to a third embodiment of the present invention.
FIG. 6 is a schematic diagram showing a configuration of a core material and a coil according to a third embodiment of the present invention.
FIG. 7 is a schematic diagram showing a configuration of a core material and a coil according to a fourth embodiment of the present invention.
[Explanation of symbols]
1, 2, 3 system power supply side terminal, 4, 5, 6 inverter equipment side terminal, 7 ground terminal, 8 common mode choke coil, L1, L2 coil element, C1, C2, C3, C5, C6, C7, C8, C9 capacitor, 9, 10, 11, 12 core material, M1, M2 magnetic flux circulating magnetic path, 14, 15 rectifier side terminal, 15, 16 inverter side terminal, 17 ground terminal, 18 common / normal mode combined choke coil, L11, L12 coil element, 19, 20 core material, M11, M12 magnetic flux circulating magnetic path, C10, C11, C12, C13 capacitor.

Claims (7)

In a device provided with a choke coil including a plurality of coil elements connected to a predetermined electric circuit and wound around a common magnetic path, the common magnetic path includes a first magnetic flux circulating magnetic path and the first magnetic flux circulating magnetic path. A second magnetic flux circulating magnetic path provided surrounding the magnetic flux circulating magnetic path, and the first magnetic flux circulating magnetic path is made of a magnetic material having a higher magnetic saturation resistance than the second magnetic flux circulating magnetic path. A noise filter, comprising: In a multi-phase circuit having a choke coil composed of a plurality of coil elements connected to each phase electric path and wound around a common magnetic path, a first magnetic flux circulating magnetic path as the common magnetic path; A second magnetic flux circulating magnetic path disposed surrounding the first magnetic flux circulating magnetic path; and providing the first magnetic flux circulating magnetic path with a magnetic saturation proof stress more than the second magnetic flux circulating magnetic path. A noise filter comprising a large magnetic material. In a multi-phase circuit having a choke coil composed of a plurality of coil elements connected to each phase electric path and wound around a common magnetic path, a first annular magnetic flux circulating magnetic path is used as the common magnetic path. And a second magnetic flux circulating magnetic path which is concentrically disposed around the first magnetic flux circulating magnetic path and has an outer diameter / inner diameter ratio different from that of the first magnetic flux circulating magnetic path. A noise filter, wherein the first magnetic flux circulating magnetic path is made of a magnetic material having a higher magnetic saturation strength than the second magnetic flux circulating magnetic path. 4. The noise filter according to claim 1, wherein a gap is provided in the second magnetic flux circulating magnetic path. In a direct-current circuit provided with a choke coil composed of a plurality of coil elements connected to each of the pole circuits and wound around a common magnetic path, wherein the common magnetic path includes a first magnetic flux circulating magnetic path, A second magnetic flux circulating magnetic path disposed surrounding the first magnetic flux circulating magnetic path; and providing the first magnetic flux circulating magnetic path with a higher magnetic saturation proof stress than the second magnetic flux circulating magnetic path. A noise filter comprising a magnetic material. In a direct-current circuit provided with a choke coil composed of a plurality of coil elements connected to each of the pole circuits and wound around a common magnetic path, wherein the common magnetic path includes a first magnetic flux circulating magnetic path, A second magnetic flux circulating magnetic path disposed surrounding the first magnetic flux circulating magnetic path; and providing the first magnetic flux circulating magnetic path with a higher magnetic saturation proof stress than the second magnetic flux circulating magnetic path. A noise filter comprising a magnetic material. The noise filter according to claim 5, wherein a gap is provided in the second magnetic flux circulating magnetic path.

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