JP6656299B2 - Noise filter - Google Patents

Description

  The present application relates to a noise filter.

As a conventional noise filter, a technique disclosed in Patent Document 1 is known. The noise filter described in Patent Literature 1 is connected between a commercial power supply and a power converter, and reduces noise generated by the power converter that is transmitted to the commercial power supply.
The noise generated by the power conversion device includes normal mode noise that propagates between lines and common mode noise that propagates between lines and ground.The noise filter has noise suppression components for each mode. I have.

FIGS. 11 and 12 show a plan view and a front view, respectively, of a noise filter described in Patent Document 1 in which only common mode noise suppression components are extracted. 11 and 12, a common mode choke coil 3 having a pair of windings 3a and 3b and line bypass capacitors (capacitors between line and ground; hereinafter simply referred to as capacitors) 40 and 50 are common mode noise suppression components. Each component is mounted on the printed wiring board 1. Here, the ground pattern 20 and the wiring pattern 6 formed on the printed wiring board 1 are shown as an example of a general pattern that can be formed when the components are arranged as shown in FIGS.
In such a noise filter, the components are arranged close to each other on the printed wiring board 1 in order to reduce the area of the printed wiring board 1 to reduce the size and cost. That is, as shown in FIG. 12, for example, the height position of the capacitor 50 on the printed wiring board 1 is set substantially equal to the height position of the common mode choke coil 3 on the printed wiring board 1.

JP 2011-60566 A JP-A-3-286511

  However, the noise filter to which the technique disclosed in Patent Document 1 is applied has a problem that the common mode choke coil 3 and the capacitors 40 and 50 are magnetically coupled.

  Here, the leakage flux of the common mode choke coil 3 is generated when a normal mode noise current flows through the common mode choke coil. FIG. 13 is an explanatory diagram of the noise filter in a state where the leakage flux of the common mode choke coil 3 is generated. As shown in FIG. 13, the leakage magnetic fluxes 100a and 100b of the common mode choke coil indicated by broken lines are linked to the loop surfaces between the leads of the capacitors 40 and 50, respectively (for example, see Patent Document 2). As a result, an induced current is generated in the common mode noise path including the capacitors 40 and 50, and the attenuation performance of the noise filter deteriorates. In particular, as shown in FIG. 12, the height position of the capacitor 50 on the printed wiring board 1 is set to be substantially the same as or higher than the height position of the common mode choke coil 3 on the printed wiring board 1. In this case, there is a problem that the common mode choke coil 3 is directly affected by the leakage magnetic flux.

  When such a noise filter is connected to a power converter, it is necessary to compensate for the degraded noise filter's attenuation performance in order to reduce the noise level generated by the power converter to a level lower than the limit value defined by the official standards. Occurs. To that end, it is necessary to add a common mode choke coil or a capacitor and increase the constant, so that an increase in the size of the noise filter and an increase in the cost are inevitable.

  On the other hand, in order to suppress the magnetic coupling between the common mode choke coil 3 and the capacitors 40 and 50, a method of shielding the common mode choke coil 3 with a magnetic member or the like is conceivable, but the area of the printed wiring board 1 becomes large, and In addition, since an additional member is required, the noise filter is increased in size and the cost is increased, so that it is difficult to adopt this method.

  The present application discloses a technique for solving the above-described problem, and suppresses magnetic coupling between a common mode choke coil and a capacitor, and is small and inexpensive which can prevent deterioration of the attenuation performance of a noise filter. It is an object to provide a simple noise filter.

The noise filter disclosed in the present application is:
A printed wiring board provided with a wiring pattern and a ground pattern,
Two common mode choke coils having a pair of windings mounted on the printed wiring board, the wiring pattern being connected to one winding of one of the common mode choke coils; A common mode choke coil in which the other common mode choke coil of the two common mode choke coils is connected in series to a wiring pattern connected to the other winding of the common mode choke coil;
When projected onto the printed wiring board together with the common mode choke coil, the capacitors are respectively arranged on the shape center lines of the respective windings of the common mode choke coil, and two capacitors mounted on the printed wiring board ,
With
One of the two capacitors is connected between a wiring pattern connected to one winding of the common mode choke coil and the ground pattern,
The other one of the two capacitors is connected between the wiring pattern connected to the other winding of the common mode choke coil and the ground pattern,
At least a portion of the one capacitor or at least a portion of the other capacitor is disposed so as to be sandwiched between the printed wiring board and one of the windings of the common mode choke coil. Thereby, the leakage magnetic flux of the common mode choke coil has a loop surface generated between the one capacitor and the printed wiring board, and a loop surface generated between the other capacitor and the printed wiring board. At least one of the loop surfaces is not crosslinked.

  According to the noise filter disclosed in the present application, since the magnetic coupling between the common mode choke coil and the capacitor is suppressed, the deterioration of the attenuation performance of the noise filter can be suppressed, and the area of the printed wiring board can be reduced. As a result, a small and inexpensive noise filter can be provided.

FIG. 2 is a configuration diagram of a noise filter according to the first embodiment. FIG. 3 is a plan view illustrating an example of a noise filter according to the first embodiment. FIG. 3 is a side view (an arrow A view) of the noise filter of FIG. 2. FIG. 3 is a front view (an arrow B view) of the noise filter of FIG. 2. FIG. 3 is an explanatory diagram of a noise filter in a state where leakage magnetic flux of the common mode choke coil of FIG. 2 is generated. FIG. 3 is a diagram illustrating an example of a noise terminal voltage waveform generated on the commercial power supply side when the power converter is connected to the noise filter according to the first embodiment and the conventional noise filter. FIG. 5 is a front view showing another example of the noise filter according to the first embodiment. FIG. 13 is a front view illustrating an example of a noise filter according to a second embodiment. FIG. 13 is a diagram illustrating a configuration example when a noise filter according to a third embodiment is connected in multiple stages. FIG. 10 is an explanatory diagram of a noise filter in a state where leakage magnetic flux is generated in a plurality of common mode choke coils according to FIG. 9. FIG. 9 is a plan view of a noise filter in which only common mode noise suppression components of the noise filter of Patent Document 1 are extracted. It is a front view of the noise filter which extracted only the common mode noise suppression parts of the noise filter of patent document 1. FIG. 12 is an explanatory diagram of the noise filter in a state where leakage magnetic flux of the common mode choke coil of FIG. 11 is generated. FIG. 7 is an explanatory diagram of a noise filter in a state where leakage magnetic flux of a common mode choke coil is generated when a conventional noise filter is connected in multiple stages.

Embodiment 1 FIG.
Hereinafter, the noise filter according to the first embodiment of the present application will be described. FIG. 1 is a diagram illustrating an example of a configuration of a noise filter according to Embodiment 1 of the present application. FIG. 2 is a plan view showing an example of the noise filter according to the first embodiment.

  As shown in FIGS. 1 and 2, the noise filter according to the first embodiment includes a common mode choke coil 3 having a pair of windings 3a and 3b and a capacitor (a capacitor between a line and a ground. Hereinafter, simply referred to as a capacitor). This is a noise filter having a single-stage configuration of LC (inductance and capacitance) composed of 4 and 5. Here, as the capacitors 4 and 5, a lead type multilayer ceramic capacitor or a lead type film capacitor is used. FIGS. 3 and 4 show a side view (a view in the direction of arrow A in FIG. 2) and a front view (a view in the direction of arrow B in FIG. 2) of the noise filter according to the first embodiment.

  As shown in FIGS. 2 to 4, the common mode choke coil 3 and the capacitor 4 or the capacitor 5 are mounted on the printed wiring board 1, and the lead terminals of the capacitor 4 or the capacitor 5 are mounted on the printed wiring board 1. And a wiring pattern 6 for connecting the components to each other.

  As shown in FIGS. 2 to 4, the common mode choke coil 3 and the capacitors 4 and 5 are mounted on the printed wiring board 1, and the lead terminals of the capacitors 4 and 5 are grounded on the printed wiring board 1. And a wiring pattern 6 for connecting the components to each other. Further, the capacitor 4 is disposed so that (at least) a part thereof is sandwiched between the printed wiring board 1 and the winding 3a of the common mode choke coil 3, and the capacitor 5 is provided between the printed wiring board 1 and the common mode choke coil. And at least a part thereof is interposed between the third winding 3b and the third winding 3b.

  As described above, the area of the printed wiring board 1 can be reduced as compared with the case of the printed wiring board disclosed in Patent Document 1. Further, the ground pattern 2 is provided for each of the capacitors 4 and 5. However, by forming the ground pattern 2 in this manner, the layout of the pattern of the printed wiring board 1 is facilitated and the area occupied by the pattern is reduced. The area of the printed wiring board 1 can be further reduced as compared with the case where the ground pattern 2 is a common ground pattern.

  Hereinafter, the principle of suppressing the deterioration of the attenuation performance of the noise filter according to the first embodiment configured as described above will be described with reference to the drawings. FIG. 5 is an explanatory diagram of the noise filter in a state where the leakage flux of the common mode choke coil 3 is generated.

  As shown in FIG. 3, the capacitor 4 is disposed with a part thereof interposed between the printed wiring board 1 and the winding 3a of the common mode choke coil 3, and the capacitor 5 is connected to the printed wiring board 1 and the common wiring. Since a part of the common mode choke coil 3 is disposed between the winding 3b of the mode choke coil 3 as shown in FIG. The loop surface formed between the capacitor 4 and the printed wiring board 1 and the loop surface generated between the capacitor 5 and the printed wiring board 1 are not linked to each other.

  As a result, the common mode choke coil 3 and the capacitors 4 and 5 do not cause magnetic coupling, and no induced current is generated in the common mode noise path including the capacitors 4 and 5, so that the deterioration of the attenuation performance of the noise filter can be suppressed. It becomes possible.

  Next, the noise attenuation performance of the above-described noise filter will be described. FIG. 6 shows a configuration in which a LISN (Line Impedance Stabilization Network) defined by CISPR 16-1-2 is connected between a commercial power supply and a noise filter to which a power conversion device is connected. Shows the noise terminal voltage observed at. Here, it is assumed that the switching noise of 100 kHz and the normal mode noise of 10 MHz generated by the power converter propagate from the power converter to the commercial power supply.

  6, a solid line P is a noise terminal voltage waveform when the noise filter according to the first embodiment is connected, a dashed line Q is a locus (envelope) of a peak value of the solid line P, and a dotted line R is a conventional one. In the locus (envelope) of the peak value of the noise terminal voltage waveform when the noise filter is connected, the broken line S is the limit value of IEC61581-21 noise specified by the international standard IEC (International Electrotechnical Commission).

  As shown in FIG. 6, since switching noise of 100 kHz propagates from the power conversion device, harmonics are generated at 100 kHz intervals in the noise spectrum with 100 kHz as a fundamental wave. Also, since normal mode noise of 10 MHz propagates from the power converter, resonance noise occurs at 10 MHz.

  Here, when attention is paid to the resonance noise of 10 MHz, it can be confirmed that the dashed line Q has a lower noise level than the dotted line R. This is because the noise filter according to the first embodiment has better attenuation performance than the conventional noise filter.

  In the case of a conventional noise filter, when a normal mode noise current of 10 MHz propagates, a magnetic coupling occurs between the common mode choke coil and the capacitor, and a common mode current of 10 MHz flows through the common mode path including the capacitors 4 and 5 and the commercial power supply side. To be propagated.

  On the other hand, in the case of the noise filter according to the first embodiment, since the magnetic coupling between the common mode choke coil and the capacitor is suppressed, a 10 MHz common mode current does not flow through the common mode path including the capacitors 4 and 5.

  Further, in the first embodiment, in the thickness direction of printed wiring board 1, capacitors 4 and 5 are portions sandwiched between printed wiring board 1 and winding 3a or winding 3b of the common mode choke coil, respectively. (See FIGS. 2 to 4), but the present invention is not limited to this. For example, as shown in FIG. 7, only one of the capacitors 4 and 5 is connected to the printed wiring board 1 and the common. A similar effect can be obtained when the (at least) part of the mode choke coil is interposed between the windings.

  In the above description, as shown in the configuration of the noise filter, the capacitors 4 and 5 are not limited to being configured by one capacitor, but are configured by connecting a plurality of capacitors in parallel. Is also good. Generally, a capacitor has a large component volume in proportion to the size of the capacitance. By configuring a capacitor having a relatively small capacity in parallel, it is possible to arrange the capacitor within the winding width of the common mode choke coil 3 in which the leakage flux of the common mode choke coil 3 is smaller. Further, it is possible to configure a noise filter in which magnetic coupling between the common mode choke coil 3 and the capacitors 4 and 5 is suppressed.

Embodiment 2 FIG.
Next, a noise filter according to the second embodiment will be described with reference to FIG.
In the noise filter according to the second embodiment, the capacitors 4a and 5a are arranged in the thickness direction of the printed wiring board 1 by being sandwiched between the printed wiring board 1 and the windings 3a and 3b of the common mode choke coil 3. However, the size in the width direction (the left and right direction in the figure) is smaller than that of the capacitors 4 and 5 of the first embodiment. 1 and the windings 3a and 3b of the common mode choke coil 3 are different from the noise filter of the first embodiment in that they are arranged so that the whole (not a part thereof) is sandwiched therebetween. In other words, the lateral width (size) of the capacitors 4a, 5a is defined by the lateral size occupied by the windings 3a, 3b of the common mode choke coil 3 (or the donut shape of the common mode choke coil 3). The noise filter according to the first embodiment is different from the noise filter according to the first embodiment in that the noise filter is arranged (defined by the contour lines of two concentric circles inside and outside).

  In the noise filter according to the second embodiment, similarly to the noise filter according to the first embodiment, the capacitors 4a and 5a are not limited to the case where each of the capacitors 4a and 5a is configured by one capacitor shown in FIG. , A plurality of capacitors may be connected in parallel.

  According to the noise filter of the second embodiment, the capacitor can be arranged within the winding width of the common mode choke coil 3 where the leakage magnetic flux of the common mode choke coil 3 is smaller, so that the common mode is further improved. It is possible to configure a noise filter in which magnetic coupling between the mode choke coil 3 and the capacitors 4 and 5 is suppressed.

Embodiment 3 FIG.
Next, a noise filter according to Embodiment 3 will be described below with reference to the drawings.
In the above-described first embodiment, a combination of both the common mode choke coil 3 having the pair of windings 3a and 3b and the capacitors 4 and 5, or any one of the common mode choke coil 3 and the capacitors 4 and 5 Although the LC composed of one combination has been described as having a single-stage configuration, in the third embodiment, the LC has a two-stage configuration, for example, a common mode choke coil 3 having a pair of windings 3a and 3b. This is a case where the combination of both capacitors 4 and 5 is one stage and this combination is two stages. The noise filter according to the third embodiment will be described below with reference to FIGS. According to the noise filters having the configurations shown in these drawings, the effect of suppressing the attenuation performance of the noise filter can be further obtained.

  FIG. 9 is a diagram showing a configuration in a case where the noise filters according to the third embodiment are connected in multiple stages to form an LC two-stage configuration. FIG. 10 is an explanatory diagram of the noise filter in a state where leakage magnetic flux is generated in the common mode choke coil 3 of the noise filter according to the third embodiment having the configuration shown in FIG.

  As shown in FIG. 10, in the present embodiment, a form in which windings 3a, 13a and 3b, 13b of two common mode choke coils 3, 13 share wiring patterns 6 shown in upper and lower two rows, respectively. It is equipped with. That is, of the two common mode choke coils 3 and 13, one common mode choke coil, for example, a wiring pattern connected to one winding 3 a of the common mode choke coil 3 and the other of the common mode choke coil 3 The other common mode choke coil 13 is connected in series to the wiring pattern connected to the winding 3b.

  In the present embodiment, the capacitor 4 is disposed in a space between the printed wiring board 1 and the winding 3a of the common mode choke coil 3, a part of which is sandwiched between the printed wiring board 1 and the common mode choke coil 3. The capacitor 14 is arranged in a space in which a part thereof is sandwiched between the winding 3b of the coil 3 and the winding 13a of the common mode choke coil 13. Since the capacitor 15 is disposed in a space between the printed wiring board 1 and the winding 13b of the common mode choke coil 13, a part thereof is sandwiched between the printed circuit board 1 and the winding 13b of the common mode choke coil 13, as shown in FIG. Leakage magnetic fluxes 100a and 100b of the common mode choke coil 3 are respectively formed by a loop surface generated between the capacitor 4 and the printed circuit board 1, The leakage fluxes 200a and 200b of the common mode choke coil 13 do not link with the loop surface generated between the printed circuit board 1 and the loop surface generated between the capacitor 14 and the printed circuit board 1, respectively. There is no linkage with a loop surface generated between the printed wiring board 15 and the printed wiring board 1.

  Thereby, the common mode choke coil 3 and the capacitors 4 and 5 do not cause magnetic coupling, the common mode choke coil 13 and the capacitors 14 and 15 do not cause magnetic coupling, the common mode noise path including the capacitors 4 and 5, and the capacitor. Since no induced current is generated in the common mode noise path including 14 and 15, it is possible to suppress the deterioration of the attenuation performance of the noise filter.

  As in the case of the first embodiment having the LC single-stage configuration, also in the case of the third embodiment having the LC two-stage configuration, the magnetic coupling between the common mode choke coil 3 and the capacitors 4, 5 and the common mode choke coil 13 , The capacitors 14 and 15 are suppressed from being magnetically coupled.

  On the other hand, FIG. 14 is an explanatory diagram of a noise filter in a state where leakage magnetic flux is generated in a plurality of common mode choke coils when a conventional noise filter has a two-stage LC configuration. As shown in FIG. 14, in the capacitors 40 and 50, in addition to the leakage magnetic fluxes 100a and 100b of the common mode choke coil 3, the leakage magnetic fluxes 200a and 200b of the common mode choke coil 13 are magnetically coupled. As compared with the case, the deterioration of the attenuation performance of the conventional noise filter becomes more remarkable.

Note that, in the present application, exemplary embodiments are described, but various features, aspects, and functions described in the embodiments are not limited to the application of the specific embodiments, and may be used alone. , Or various combinations are applicable to the embodiments.
Accordingly, innumerable modifications not illustrated are contemplated within the scope of the technology disclosed herein. For example, it is assumed that at least one component is modified, added or omitted. Specifically, for example, in the third embodiment, the arrangement of the capacitors may have two sets of the arrangement of the capacitors shown in FIG. 7, and the arrangement of the capacitors of FIGS. 2 and 11 may be provided. In each case, the attenuation performance of the noise filter is better than that of the conventional noise filter.

  Reference Signs List 1 printed wiring board, 2 ground pattern, 3, 13 common mode choke coil, 3a, 3b, 13a, 13b winding, 4, 4a, 5, 5a, 14, 15 capacitor, 6 wiring pattern, 100a, 100b, 200a, 200b Leakage flux

Claims (3)

A printed wiring board provided with a wiring pattern and a ground pattern,
Two common mode choke coils having a pair of windings mounted on the printed wiring board, and a wiring pattern connected to one winding of one of the common mode choke coils; A common mode choke coil in which the other common mode choke coil of the two common mode choke coils is connected in series to a wiring pattern connected to the other winding of the common mode choke coil;
When projected onto the printed wiring board together with the common mode choke coil, the capacitors are respectively arranged on the shape center lines of the respective windings of the common mode choke coil, and two capacitors mounted on the printed wiring board ,
With
One of the two capacitors is connected between a wiring pattern connected to one winding of the common mode choke coil and the ground pattern,
The other one of the two capacitors is connected between the wiring pattern connected to the other winding of the common mode choke coil and the ground pattern,
At least a portion of the one capacitor or at least a portion of the other capacitor is disposed so as to be sandwiched between the printed wiring board and one of the windings of the common mode choke coil. Thereby, the leakage magnetic flux of the common mode choke coil has a loop surface generated between the one capacitor and the printed wiring board, and a loop surface generated between the other capacitor and the printed wiring board. A noise filter characterized in that it does not interlink at least one of the loop surfaces. At least a part of the one capacitor is disposed so as to be sandwiched between the printed wiring board and one winding of the common mode choke coil,
The noise filter according to claim 1, wherein at least a part of the other capacitor is disposed between the printed wiring board and the other winding of the common mode choke coil. The ground pattern, noise filter according to claim 1 or claim 2, characterized in that are respectively provided on the one capacitor and the other capacitor.

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