JP6189084B2 - Noise filter - Google Patents

Description

  The present invention relates to a noise filter connected between a power source and an electric device. More specifically, the present invention relates to a noise filter that clears European noise standard EN55011 Group 1 Class B (hereinafter referred to as noise standard Class B).

  As a noise filter connected between the power source and the electric device, for example, a noise filter 100 shown in FIG. This noise filter 100 includes at least X capacitors C1 to C3 (interphase capacitors) and common mode choke coils L1 to L3 connected to power supply lines 106a to 106c wired between input terminals 102a to 102c and output terminals 104a to 104c. Capacitors (hereinafter referred to as XY capacitors C4 to C7) in which X capacitors C4 to C6 (interphase capacitors) and Y capacitors C7 (ground capacitors) connected to the ground lines 108a to 108c from the power supply lines 106a to 106c toward the ground GND are connected in a star manner. .) The common mode choke coils L1 to L3 are configured by winding three power supply lines 106a to 106c on a circular toroidal core 110 made of ferrite, for example, for two or more turns. The XY capacitors C4 to C7 may be configured by delta connection instead of star connection, or the X capacitors C4 to C6 (interphase capacitors) may be omitted, and the Y capacitors C7 (grounding) may be connected to the ground lines 108a to 108c. (Capacitor) may be connected.

  The noise filter 100 depends on the noise level emitted from the electric device, but by appropriately setting the constants of the X capacitors C1 to C3, the common mode choke coils L1 to L3 and the XY capacitors C4 to C7 of the noise filter 100, European noise standard EN55011 Group 1 Class A can be cleared.

  Then, in order to further increase the high-frequency / wideband noise attenuation amount of several hundred kHz to several tens of MHz and clear the noise standard Class B, for example, as shown in the noise filter 200 of FIG. Examples include a configuration in which coils L4 to L6 are added to the output side of the noise filter 100. For example, noise filters disclosed in Patent Documents 1 to 4 are known.

  In Patent Document 1, a second common mode choke coil is added to the output side of a normal noise filter, and a Y capacitor is interposed between the common mode choke coil and the second common mode choke coil in the normal noise filter. An example in which is connected is described.

  Patent Document 2 describes an example in which a second noise filter is added to the output side of a normal noise filter. The second noise filter has a common mode choke coil and a Y capacitor connected to the output side of the common mode choke coil.

  Patent Document 3 describes an example in which a second balanced inductance coil is added to the output side of a normal noise filter.

  Patent Document 4 describes an example in which a third coil is added to the input side of a two-stage noise filter.

JP 2000-340437 A JP 09-116367 A JP 07-212165 A JP 05-292669 A

  However, the noise filter described in Patent Document 1 described above increases in size when an externally attached second common mode choke coil is added, and even if the noise filter is incorporated in the housing, the common noise filter in the normal noise filter is used. A Y capacitor (grounded capacitor) must be connected between the mode choke coil and the second common mode choke coil. The size of the connecting terminal increases, the number of parts increases, and the number of wiring work increases. There is a problem of doing.

  In addition, if a Y capacitor is accommodated under the output terminal block to reduce the size, the wiring must be routed from the connection terminal described above, and the characteristics may change depending on how the wiring is routed. . Therefore, although there is a possibility that the noise standard Class B can be achieved depending on how each constant is set, there is a problem that the range is narrow and the degree of freedom in design is small.

  The noise filter described in Patent Document 2 has a multi-stage configuration by adding a second noise filter to the output side of a normal noise filter, so that the size is expected to be nearly twice that of a normal noise filter. .

  The noise filter described in Patent Document 3 may be larger in size than Patent Document 1 because the second balanced inductance coil connected to the output side of a normal noise filter also uses a toroidal core. is there.

  Since the noise filter described in Patent Document 4 has a multi-stage configuration in which a third coil is connected to the input side of a two-stage noise filter, three coils must be connected, and the size is normal noise. Expected to be more than twice the filter.

  The present invention has been made in view of such problems, and further increases the noise attenuation amount of high frequency / broadband of several hundred kHz to several tens of MHz with a simple structure without causing an increase in size, An object of the present invention is to provide a noise filter that can clear the noise standard Class B.

[1] A noise filter according to the present invention is connected to at least an interphase capacitor and a common mode choke coil connected to a power supply line wired between an input terminal and an output terminal, and a ground line from the power supply line to the ground. A noise filter having a grounding capacitor, comprising: a first coil connected to the power supply line on an output side of the common mode choke coil; and a second coil connected to the grounding line; The core and the core of the second coil are formed of a common core, and the ground line is wired between the output terminal and the ground.

[2] In this case, the first coil is a first through-type coil in which the power supply line penetrates the common core, and the second coil is a second coil in which the ground line penetrates the common core. A through-type coil may be used.

[3] Also, an input terminal block in which the input terminal is installed and an output terminal block in which the output terminal is installed, and the common mode choke coil is between the input terminal block and the output terminal block. The common core may be installed between the common mode choke coil and the output terminal block.

[4] In this case, the core of the common mode choke coil may be a toroidal core, and the toroidal core may be arranged vertically.

  According to the noise filter of the present invention, the noise attenuation amount of a high frequency / broadband of several hundred kHz to several tens of MHz is further increased and the noise standard Class B is cleared with a simple structure without causing an increase in size. Can do.

It is a circuit diagram which shows the structure of the noise filter which concerns on this Embodiment. It is a perspective view which abbreviate | omits and shows the example of a 1st coil (1st penetration type coil) and a 2nd coil (2nd penetration type coil). It is a longitudinal cross-sectional view which abbreviate | omits and shows the structural example of the noise filter which concerns on this Embodiment. It is a top view which abbreviate | omits and shows the structural example of the noise filter which concerns on this Embodiment. 5A and 5B are explanatory views showing an example in which the toroidal cores constituting the common mode choke coil are arranged vertically. It is the graph which measured the noise terminal disturbance voltage (Conducted Emisson). It is a circuit diagram which shows the prior art example of a structure of a general noise filter. FIG. 6 is a circuit diagram showing an improved conventional example in which an external coil is connected to the output side of a general noise filter.

  Hereinafter, an embodiment in which the noise filter according to the present invention is applied to, for example, a three-phase three-wire noise filter will be described with reference to FIGS.

  As shown in FIG. 1, the noise filter 10 according to the present embodiment includes at least X capacitors C1 to C3 (connected to power supply lines 16a to 16c wired between the input terminals 12a to 12c and the output terminals 14a to 14c. Interphase capacitors), common mode choke coils L1 to L3, and XY capacitors C4 to C7 connected to ground lines 18a to 18c from the power supply lines 16a to 16c toward the ground GND. The common mode choke coils L1 to L3 are configured by winding three power supply lines 16a to 16c on a circular toroidal core 20 made of ferrite, for example, for two or more turns. The XY capacitors C4 to C7 may be configured by delta connection instead of star connection, or the X capacitors C4 to C6 (interphase capacitors) may be omitted, and the Y capacitors C7 (grounding) may be connected to the ground lines 18a to 18c. A capacitor) may be connected.

  The noise filter 10 further includes first coils L4 to L6 connected to the power supply lines 16a to 16c on the output side of the common mode choke coils L1 to L3, and a second coil connected to the ground lines 18a to 18c. L7 to L9.

  The ground lines 18a to 18c are wired between the output terminals 14a to 14c and the ground GND. The XY capacitors C4 to C7 are connected between the second coils L7 to L9 and the ground GND.

  The cores of the first coils L4 to L6 and the cores of the second coils L7 to L9 are constituted by one common core (hereinafter referred to as a common core 22) made of ferrite, for example. Since the common core 22 is used, the first coils L4 to L6 and the second coils L7 to L9 have an effect of canceling the parasitic inductance of the XY capacitor. From this viewpoint, the first coils L4 to L6 and the second coils L7 to L9 are effective. It is desirable that the coil conditions of L9 are the same.

  For example, as shown in FIG. 2, the common core 22 is configured by a track-shaped toroidal core. That is, the first coils L4 to L6 are first through-type coils in which the power supply lines 16a to 16c pass through the common core 22, and the ground lines 18a to 18c pass through the common core 22 in the second coils L7 to L9. It is a 2nd penetration type coil.

  The first coils L4 to L6 and the second coils L7 to L9 may have inductance values lower than those of the common mode choke coils L1 to L3 in order to reduce the stray capacitance between the lines. Thereby, a structure is possible with the first through-type coil and the second through-type coil.

  Here, a configuration example of the noise filter 10 according to the present embodiment will be described with reference to FIGS. 3 and 4, the upper case of the housing and the X capacitors C1 to C3 are not shown.

  As shown in FIGS. 3 and 4, the noise filter 10 includes a box-shaped housing 24. The housing 24 is provided on the bottom plate 26, one end of the bottom plate 26, the input terminal block 28 on which the input terminals 12 a to 12 c are installed, and the other end of the bottom plate 26. And the output terminal base 30 in which the output terminals 14a-14c were installed.

  The common mode choke coils L <b> 1 to L <b> 3 are installed in the accommodation space 32 between the input terminal block 28 and the output terminal block 30. In particular, in the present embodiment, the toroidal core 20 constituting the common mode choke coils L1 to L3 is arranged vertically. As shown in FIGS. 5A and 5B, the longitudinal direction means that the direction of the axis Da of the toroidal core 20 is substantially parallel to the horizontal line Dh. For example, the angle θ between the direction of the axis Da and the horizontal line Dh is − The relationship is 45 ° to + 45 °. The common mode choke coils L <b> 1 to L <b> 3 may be arranged in a lateral direction in which the direction of the axis Da of the toroidal core 20 is substantially perpendicular to the horizontal line Dh. This is advantageous for a low-profile noise filter.

  By installing the toroidal core 20 vertically, a wide space 34 is formed above the portion of the toroidal core 20 facing the output terminal block 30 as shown in FIG. It becomes possible to install the common core 22 at the same time. Thereby, it is not necessary to separately provide a new accommodation space for providing the first coils L4 to L6 and the second coils L7 to L9, and it is not necessary to provide them externally. As a result, an increase in the size of the noise filter 10 can be avoided, and a low-bottom type noise filter with a small bottom plate area of the housing can be obtained.

  Furthermore, the ground lines 18a to 18c are wired between the output terminals 14a to 14c and the ground GND (for example, the bottom plate 26). That is, the output terminals 14a to 14c function as common terminals for the output sides of the power supply lines 16a to 16c and the ground lines 18a to 18c. Therefore, it is not necessary to provide a new terminal block for connecting the ground lines 18a to 18c to each of the power supply lines 16a to 16c, and an increase in the size of the noise filter 10 can be avoided, resulting in a simple structure.

  Further, as shown in FIG. 3, the XY capacitors C4 to C7 are housed in the space between the output terminal block 30 and the bottom plate 26 in the casing 24 as the capacitor block 36, thereby installing the XY capacitors C4 to C7. Therefore, it is not necessary to provide a new storage space for the noise filter 10, and an increase in the size of the noise filter 10 can be avoided.

  Thus, the noise filter 10 according to the present embodiment is connected to the first coils L4 to L6 connected to the power supply lines 16a to 16c and the ground lines 18a to 18c on the output side of the common mode choke coils L1 to L3. Since the second coils L7 to L9 and the cores of the first coils L4 to L6 and the cores of the second coils L7 to L9 are configured by one common core 22, the size of the noise filter 10 can be increased. Without incurring, it is possible to further increase the noise attenuation amount of a high frequency / broadband of several hundred kHz to several ten MHz with a simple structure and clear the noise standard Class B.

  Here, the result of having measured the noise terminal disturbance voltage (Conducted Emisson) about an Example and a prior art example is demonstrated, referring FIG. FIG. 6 is a graph in which a noise terminal disturbing voltage (Conducted Emisson) is measured, and a curve A indicates a measurement result when the noise filter 10 is not connected to the power supply lines 16a to 16c, that is, when no countermeasure is taken. Is the noise level. A curve B shows a measurement result of the noise filter 100 of the conventional example showing the circuit configuration of FIG. 7, and a curve C shows a measurement result of the noise filter 10 of the embodiment showing the circuit configuration of FIG. Note that both the example and the conventional example have the same size and the same shape.

  The curve C in the embodiment has a larger noise attenuation amount than the curve B in the conventional example, particularly in a band from 400 kHz to several tens of MHz, and the noise standard Class B is cleared.

  In the above-described embodiment, the structure is a through-type coil. However, a through-type coil having a plurality of cores may be used depending on the set values of the inductance values of the first coils L4 to L6 and the second coils L7 to L9. It is good also as a structure wound around a core.

  The noise filter according to the present invention is not limited to the above-described embodiment, and can of course have various configurations without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 ... Noise filter 12a-12c ... Input terminal 14a-14c ... Output terminal 16a-16c ... Power supply line 18a-18c ... Ground line 20 ... Toroidal core 22 ... Common core 28 ... Input terminal block 30 ... Output terminal block 34 ... Space 36 ... Capacitor blocks C1 to C3 ... X capacitors C4 to C7 ... XY capacitors GND ... Grounds L1 to L3 ... Common mode choke coils L4 to L6 ... First coils L7 to L9 ... Second coils

Claims (3)

In a noise filter having at least an interphase capacitor connected to a power supply line wired between an input terminal and an output terminal, a common mode choke coil, and a grounding capacitor connected to a ground line from the power supply line to the ground,
A first coil connected to the power line on the output side of the common mode choke coil, and a second coil connected to the ground line;
The core of the first coil and the core of the second coil are constituted by one common core,
The noise filter, wherein the ground line is wired between the output terminal and a ground. The noise filter according to claim 1.
The first coil is a first through-type coil in which the power line penetrates the common core,
The noise filter, wherein the second coil is a second through-type coil in which the ground line penetrates the common core. The noise filter according to claim 1 or 2,
An input terminal block on which the input terminal is installed;
An output terminal block on which the output terminal is installed,
The common mode choke coil is installed between the input terminal block and the output terminal block;
The noise filter, wherein the common core is disposed between the common mode choke coil and the output terminal block.

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