JP6251221B2 - Noise filter device - Google Patents

Description

The invention, for example, relates to a noise filter equipment for use in power conversion device such as a high-power electrical devices or inverter.

  As a countermeasure against power supply line common mode noise, a circuit having a common mode coil, a ground capacitor, or both is used (see Patent Document 1). This circuit is generally called a noise filter.

  The noise filter disclosed in Patent Document 2 includes a common mode reactor connected to each of the three-phase power lines, and three series circuits connected between each power line and the ground. Each series circuit is configured by connecting a line capacitor and a reactor in series.

  FIG. 4 of Patent Document 2 includes a common mode reactor having three coils connected in series to a power supply line that supplies a three-phase voltage, and three line capacitors that are star-connected to the power supply line. A noise filter is described. The noise filter further includes a circuit in which a series circuit connected between the neutral point of the three line capacitors and the ground and a ground capacitor are connected in parallel. The series circuit is configured by connecting a capacitor and a reactor in series.

  In the circuit described in FIG. 4 of Patent Document 2, the capacitance of the series circuit and the inductance of the reactor are set so that the resonance frequency of the series circuit is equal to or higher than the self-resonance frequency of the common mode reactor. In addition, the capacitor connected in parallel to the series circuit sets the frequency characteristics so as to have a capacitance component even in the high frequency band, so that the attenuation effect of the noise filter is maintained in the high frequency band.

JP 2012-066551 A JP 2008-245037 A

  By the way, a ground filter or a noise filter having a ground capacitor is connected to the power source. When one phase of the power source is grounded, a leakage current of a commercial frequency component (hereinafter, referred to as a power frequency) (Referred to as commercial frequency leakage current). This leakage current value has a safety standard and is generally suppressed to 3 mA or less as a guide. In the power supply of the above-described type, the capacitance value of the grounding capacitor is limited to 10,000 pF or less per phase. Depending on the device, the leakage current value may be limited to 1 mA or less, and the capacitance value of the grounding capacitor may be limited to 3300 pF or less per phase.

  For this reason, even in the circuit described in Patent Document 2, when the capacitance value of the grounding capacitor is limited, there is a problem that the noise attenuation effect is reduced.

  Therefore, even if the capacitance value of the grounding capacitor is limited, it is conceivable to increase the inductance value of the common mode coil by using a large core or a special core in order to further attenuate the noise.

  However, when a large core or a special core is used, there is a problem that the size of the noise filter itself is increased and the manufacturing cost is increased.

The present invention has been made in consideration of such a problem. When one phase of a power supply is grounded, the commercial frequency leakage current can be reduced without impairing the noise attenuation effect by the grounding capacitor. can, and an object thereof is to provide a noise filter equipment capable of reducing the size and cost reduction of the size.

[1] A noise filter device according to a first aspect of the present invention is a noise filter device having a noise filter connected between a power source in which one phase is a ground phase and a power converter, and the power source A common mode coil connected to a plurality of power lines between the power converters; a plurality of line capacitors star-connected to the plurality of power lines; and at least one ground connected between the power line and the ground. It has a capacitor | condenser and the compensation circuit which reduces the leakage current of the commercial frequency component by the said power supply.

[2] In the first aspect of the present invention, the compensation circuit has the ground capacitor at a frequency of the power source with respect to the leakage current flowing from the power line to the ground that is generated in proportion to the capacitance of the ground capacitor. In addition, a coil that resonates in parallel may be included.

[3] In this case, the grounding capacitor may be connected between a neutral point of the plurality of line capacitors and the ground, and the coil constituting the compensation circuit may be connected in parallel to the grounding capacitor. .

[4] Also, the power supply line includes the same number of the grounding capacitors and coils as the number of the plurality of power supply lines, and the grounding capacitors are connected between the power supply lines and the ground, respectively. The coil constituting the compensation circuit may be connected.

[5] In the first aspect of the present invention, the power source is a first power source having a power frequency of a first frequency or a second power source having a power frequency of a second frequency, and is first between the power line and ground. A grounding capacitor and a second grounding capacitor are connected in series, and the compensation circuit is configured to prevent the leakage current flowing from the power line to the ground that is generated in proportion to the capacitance of the first grounding capacitor. A first coil that resonates in parallel with the first grounded capacitor at a frequency, and the leakage current that flows in proportion to the capacitance of the second grounded capacitor from the power supply line to the ground at the second frequency. A second coil that resonates in parallel with the second grounding capacitor may be included. In this case, the first frequency is, for example, 50 Hz, and the second frequency is, for example, 60 Hz.

[6] In the first aspect of the present invention, a first ground capacitor and a second ground capacitor are connected in series between the power line and the ground, and the compensation circuit is proportional to the capacitance of the first ground capacitor. The leakage current flowing from the power line to the ground is generated in proportion to the first coil that resonates in parallel with the first ground capacitor at the frequency of the power source and the capacitance of the second ground capacitor. A second coil that resonates in parallel with the second grounding capacitor with a distortion component of the frequency of the power supply with respect to the leakage current flowing from the power supply line to the ground.

[7] In the first aspect of the present invention, one or more noise filters may be connected to the power source, and at least one of the noise filters may include a compensation circuit that reduces a leakage current of a commercial frequency component due to the power source. Good.

[8] In this case, the compensation circuit is proportional to the capacitance of the grounding capacitor of one of the noise filters, and is generated in proportion to the number of the noise filters connected to the power supply. The coil may resonate in parallel with the grounding capacitor at the frequency of the power supply with respect to the leakage current flowing from the ground to the ground.

[9] Furthermore, the coil has a plurality of taps, and the compensation circuit changes the inductance value of the coil by switching the taps according to the number of the noise filters connected to the power source. You may have a switching means.

As described above, according to the noise filter equipment according to the present invention, in the case where one phase of the power source is grounded, without compromising the damping effect of noise due to grounding capacitor, reducing the commercial frequency leakage currents Thus, the size can be reduced and the cost can be reduced.

It is a circuit diagram which shows the structure of the noise filter apparatus (1st noise filter apparatus) which concerns on 1st Embodiment. It is a graph which shows the change of the impedance with respect to the frequency between the output terminal of a noise filter, and earth | ground about the result of a 1st experiment example, ie, Example 1, Reference example 1A, and 1B. It is a graph which shows the attenuation characteristic about the result of the 2nd experiment example, ie, Example 2, and Reference example 2. FIG. It is a circuit diagram which shows the structure of the noise filter apparatus concerning the reference example 3. It is a graph which shows the attenuation characteristic about the result of a 3rd experiment example, ie, Example 3, and Reference Example 3. FIG. 6A to 6C are graphs showing changes in harmonic leakage current and commercial frequency leakage current for the results of the fourth experimental example, that is, Example 4 and Reference Examples 4A and 4B. 7A and 7B are graphs showing the BH characteristics of the magnetic material of the common mode coil according to the harmonic leakage current for the results of the fifth experimental example, that is, Example 5 and Reference Example 5. FIG. It is a circuit diagram which shows the structure of the noise filter apparatus (2nd noise filter apparatus) which concerns on 2nd Embodiment. It is a circuit diagram which shows the structure of the noise filter apparatus (3rd noise filter apparatus) which concerns on 3rd Embodiment. It is a graph which shows the change of the impedance with respect to the frequency between the output terminal of a noise filter, and earth | ground about the result of a 6th experiment example, ie, Example 6, Reference example 1A and 1B. It is a circuit diagram which shows the structure of the noise filter apparatus (4th noise filter apparatus) which concerns on 4th Embodiment. It is a graph which shows the change of the impedance with respect to the frequency between the output terminal of a noise filter, and earth | ground about the result of a 7th experiment example, ie, Example 7, and reference examples 1A and 1B. FIG. 9 is a circuit diagram showing an example of a configuration of a noise filter device (fifth noise filter device) according to a fifth embodiment, in particular, one noise filter connected. FIG. 9 is a circuit diagram showing an example of a configuration of a fifth noise filter device, in particular, where two noise filters are connected. FIG. 10 is a circuit diagram showing an example of a configuration of a fifth noise filter device, in particular, three noise filters connected. It is a circuit diagram which shows the structure of the power supply line filter apparatus which concerns on this Embodiment.

  Embodiments of a noise filter device and a power line filter device according to the present invention will be described below with reference to FIGS.

  First, the noise filter device according to the first embodiment (hereinafter referred to as the first noise filter device 10A) is a noise connected between the AC power supply 12 and the power conversion device 14 as shown in FIG. A filter 16 is included. As the AC power supply 12, for example, a three-phase three-wire power supply can be used. In this case, one phase, for example, the S phase is the ground phase.

  The noise filter 16 includes three common mode coils 20a to 20c connected to the three power supply lines 18a to 18c between the AC power supply 12 and the power converter 14, and three star connections to the three power supply lines 18a to 18c. Line capacitors 22a to 22c, one power supply line 18a to 18c, and one ground capacitor 24 connected between ground GND are provided.

  The common mode coils 20a to 20c are configured by winding three power supply lines 18a to 18c around a magnetic body 26 for one turn or more. The line capacitors 22a to 22c may be configured not by star connection but by delta connection. Moreover, the magnetic body 26 can be comprised with the circular toroidal core comprised, for example with the ferrite.

  The first noise filter device 10 </ b> A includes a first compensation circuit 28 </ b> A that reduces a leakage current of a commercial frequency component (hereinafter referred to as a commercial frequency leakage current ia) from the AC power supply 12.

  The first compensation circuit 28A performs parallel resonance with the ground capacitor 24 at the frequency of the AC power supply 12 with respect to the commercial frequency leakage current ia flowing from the power supply lines 18a to 18c to the ground GND in proportion to the capacitance of the ground capacitor 24. A coil 30 is provided.

  Specifically, the ground capacitor 24 is connected between the neutral point 32 of the plurality of line capacitors 22a to 22c and the ground GND. The coil 30 constituting the first compensation circuit 28A is connected in parallel to the ground capacitor 24.

  Here, the operation of the first noise filter device 10A will be described with reference to FIG.

  First, the current flowing through the ground capacitor 24 of the noise filter 16 that mainly attenuates the common mode noise includes the commercial frequency leakage current ia determined by the capacitance value of the ground capacitor 24, the power supply frequency and the power supply voltage, and the noise filter 16. It is divided into a leakage current of harmonic components (hereinafter referred to as harmonic leakage current ib) generated from common mode noise flowing out to the input line of the power conversion device 14 which is a noise source connected to.

  The value of the commercial frequency leakage current ia is determined by multiplying the capacitance of the ground capacitor 24 by the power supply voltage / frequency. Further, the commercial frequency leakage current ia flows through the ground phase line of the AC power supply 12.

  The harmonic leakage current ib generated from the common mode noise is returned to the power conversion device 14 that is a noise generation source through the ground capacitor 24 by the frequency component, the voltage, and the electrostatic capacitance of the ground capacitor 24. Due to the electrostatic capacitance of the ground capacitor 24, a part of the harmonic leakage current ib returns to the power converter 14 of the generation source through the ground phase line. In this case, the power supply system is affected as the harmonic leakage current ib.

  In addition to the grounding capacitor 24, the common mode coils 20a to 20c act as impedances against the common mode noise and suppress the outflow to the power supply system. That is, the suppression of the common mode noise is due to the synergistic effect of the grounding capacitor 24 and the common mode coils 20a to 20c.

  Therefore, by increasing both the capacitance value of the grounding capacitor 24 and the inductance values of the common mode coils 20a to 20c, the effect of suppressing common mode noise increases. However, if the capacitance value of the grounding capacitor 24 is increased, commercial frequency leakage The current ia becomes large, which is not preferable. On the other hand, when the common mode coil is enlarged, the shape of the noise filter is increased, and there is a problem that the cost is increased due to the use of a special core.

  That is, the harmonic leakage current ib generates a magnetic flux in the magnetic body 26 (normally closed circuit) used in the common mode coils 20a to 20c constituting the noise filter 16, and the magnetic flux 26 (normally closed) is generated. When the saturation magnetic flux density of the circuit) is reached, the inductance values of the common mode coils 20a to 20c are lowered, and the noise attenuation effect is reduced.

  Therefore, as described above, the common mode coils 20a to 20c are configured by increasing the capacitance value of the grounding capacitor 24 of the noise filter 16 and returning the harmonic leakage current ib to the power converter 14 that has generated the noise. It is conceivable to take measures to lower the magnetic flux generated in the magnetic body 26 to be below the saturation magnetic flux density.

  However, when the electrostatic capacitance of the grounding capacitor 24 is increased, the commercial frequency leakage current ia increases and exceeds the leakage current standard value defined by the safety standard. Therefore, the capacitance value of the ground capacitor 24 cannot be simply increased.

  On the other hand, the first noise filter device 10A includes the first compensation circuit 28A that reduces the commercial frequency leakage current ia from the AC power supply 12 as described above. The first compensation circuit 28 </ b> A is a coil 30 that resonates in parallel with the grounding capacitor 24 at the frequency of the AC power supply 12 with respect to a leakage current flowing from the power supply lines 18 a to 18 c to the ground GND in proportion to the capacitance of the grounding capacitor 24. Have That is, in the first noise filter device 10A, the coil 30 having an inductance value that resonates with the power supply frequency is connected in parallel to the capacitance value of the grounding capacitor 24. Therefore, the first noise filter device 10A The frequency leakage current ia can be reduced.

  Further, since the capacitance of the grounding capacitor 24 can be increased, the inductance values of the common mode coils 20a to 20c can be reduced, and the volume occupied by the common mode coils 20a to 20c and the magnetic body 26 can be reduced. be able to. As a result, an inexpensive and small noise filter device can be obtained.

  Here, five experimental examples will be described with reference to FIGS.

[First Experimental Example]
In the first experimental example, changes in impedance with respect to frequency were confirmed for Example 1 and Reference Examples 1A and 1B.

  In Example 1, in the first noise filter device 10A described above, the inductance value of each of the common mode coils 20a to 20c was 500 μH, and the capacitance value of the ground capacitor 24 was 0.3 μF. Further, the inductance value of the coil 30 was adjusted so that the coil 30 and the ground capacitor 24 resonate in parallel at a frequency of 50 Hz.

  The reference example 1A has a configuration in which the coil 30 is removed from the above-described first embodiment. In Reference Example 1B, in Example 1 described above, the coil 30 was removed, and the capacitance value of the grounding capacitor 24 was set to 0.03 μF.

  The results are shown in FIG. In FIG. 2, the characteristic of Example 1 is indicated by a solid line L1, the characteristic of Reference Example 1A is indicated by a broken line S1A, and the characteristic of Reference Example 1B is indicated by a one-dot chain line S1B. That is, FIG. 2 is a graph showing a change in impedance between the output terminal of the noise filter 16 and the ground GND. A broken line S1A (Reference Example 1A) indicates the impedance characteristics of the combination of the line capacitors 22a to 22c and the ground capacitor 24 (0.3 μF), and a one-dot chain line S1B (Reference Example 1B) indicates the line capacitors 22a to 22c. The impedance characteristic of the combination of 22c and the grounding capacitor 24 (0.03 μF) is shown. A solid line L1 (Example 1) indicates impedance characteristics of a combination of the line capacitors 22a to 22c, the ground capacitor 24 (0.3 μF), and the first compensation circuit 28A.

  First, when the reference example 1A and the reference example 1B are compared, the impedance of the reference example 1A in which the capacitance value of the ground capacitor 24 is large is lower than that of the reference example 1B. Therefore, it can be seen that increasing the capacitance value of the grounding capacitor 24 increases the noise attenuation effect. However, in Reference Example 1A, since the impedance is reduced even at a commercial frequency (here, 50 Hz), the commercial frequency leakage current ia increases as compared to Reference Example 1B.

  On the other hand, since Example 1 has a configuration in which the coil 30 is connected in parallel to the ground capacitor 24, the impedance of the noise band frequency is reduced similarly to Reference Example 1A, and the impedance of the commercial frequency is higher than that of Reference Example 1B. It has become. Therefore, in Example 1, the noise attenuation effect is large, and the commercial frequency leakage current ia is reduced as compared with the case of Reference Example 1B.

  Thus, it can be seen that the noise filter device according to the first embodiment can reduce the commercial frequency leakage current ia without impairing the noise attenuation effect by the ground capacitor 24.

[Second Experimental Example]
In the second experimental example, the attenuation characteristics of Example 2 and Reference Example 2 were confirmed.

  In Example 2, in the first noise filter device 10A described above, the inductance value of each of the common mode coils 20a to 20c was 50 μH, and the capacitance value of the ground capacitor 24 was 0.3 μF. Further, the inductance value of the coil 30 was adjusted so that the coil 30 and the ground capacitor 24 resonate in parallel at a frequency of 50 Hz.

  The reference example 2 has a configuration in which the coil 30 is removed from the above-described embodiment 2, and the inductance values of the common mode coils 20a to 20c are 500 μH. The capacitance value of the grounding capacitor 24 was 0.03 μF.

  That is, the inductance value of each common mode coil 20a to 20c of the second embodiment is 1/10 compared to the reference example 2.

  The attenuation characteristics of Example 2 and Reference Example 2 are shown in FIG. In FIG. 3, the characteristic of Example 2 is indicated by a solid line L2, and the characteristic of Reference Example 2 is indicated by a broken line S2.

  From the results of Example 2 and Reference Example 2, it can be seen that the attenuation characteristics of both are almost the same. In other words, in the second embodiment, by connecting the coil 30 to the ground capacitor 24 in parallel, the commercial frequency leakage current can be reduced without impairing the attenuation effect of the common mode noise. Can be increased. As a result, the inductance values of the common mode coils 20a to 20c can be lowered, the volume occupied by the common mode coils 20a to 20c and the magnetic body 26 can be reduced, and the inexpensive and small noise filter device. Can be obtained.

[Third experimental example]
In the third experimental example, the attenuation characteristics of Example 3 and Reference Example 3 were confirmed.

  In Example 3, in the first noise filter device 10A described above, the inductance value of each of the common mode coils 20a to 20c was 500 μH, and the capacitance value of the grounding capacitor 24 was 0.3 μF. Further, the inductance value of the coil 30 was adjusted so that the coil 30 and the ground capacitor 24 resonate in parallel at a frequency of 50 Hz.

  As shown in FIG. 4, the reference example 3 has a configuration in which the first common mode coils 20a1 to 20c1 are connected to the power supply lines 18a to 18c, and the second common mode coils 20a2 to 20c2 are further connected. As described above, the first common mode coils 20a1 to 20c1 are configured by winding the three power lines 18a to 18c on the circular first toroidal core 26A made of ferrite for two or more turns. . The second common mode coils 20a2 to 20c2 are configured by winding three power supply lines 18a to 18c on a circular second toroidal core 26B, which is also made of ferrite, for two or more turns. The inductance values of the first common mode coils 20a1 to 20c1 and the second common mode coils 20a2 to 20c2 are 500 μH, respectively. The capacitance value of the grounding capacitor 24 is 0.03 μF.

  That is, Reference Example 3 has a configuration of a high attenuation type noise filter in which two types of common mode coils (first common mode coils 20a1 to 20c1 and second common mode coils 20a2 to 20c2) are connected.

  The attenuation characteristics of Example 3 and Reference Example 3 are shown in FIG. In FIG. 5, the characteristic of Example 3 is indicated by a solid line L3, and the characteristic of Reference Example 3 is indicated by a broken line S3.

  From the results of Example 3 and Reference Example 3, it can be seen that the attenuation characteristics of both are almost the same. That is, Example 3 has the same attenuation characteristics as a high attenuation type noise filter using two types of common mode coils, although only one type of common mode coils 20a to 20c is used. You can see that

  As described above, since the coil 30 is connected in parallel to the grounding capacitor 24 in the same manner as in the second embodiment, the commercial frequency leakage current can be reduced without impairing the attenuation effect of the common mode noise. The capacitance of the capacitor 24 can be increased. As a result, even if the inductance values of the common mode coils 20a to 20c are lowered, it is possible to obtain the same attenuation characteristics as the high attenuation type noise filter shown in the reference example 3, and the common mode coils 20a to 20c and the magnetic body can be obtained. The volume occupied by 26 can be reduced, and an inexpensive and small noise filter device can be obtained.

[Example 4]
In the fourth experimental example, changes in the harmonic leakage current and the commercial frequency leakage current were confirmed for Example 4 and Reference Examples 4A and 4B.

  In Example 4, in the first noise filter device 10A described above, the inductance value of each of the common mode coils 20a to 20c was 500 μH, and the capacitance value of the grounding capacitor 24 was 0.3 μF. Further, the inductance value of the coil 30 was adjusted so that the coil 30 and the ground capacitor 24 resonate in parallel at a frequency of 50 Hz.

  In Reference Example 4A, in Example 4 described above, the coil 30 was removed, and the capacitance value of the grounding capacitor 24 was set to 0.03 μF. In Reference Example 4B, in Example 4 described above, the coil 30 was removed, and the capacitance value of the grounding capacitor 24 was set to 0.3 μF.

  The results are shown in FIGS. 6A to 6C. 6A shows the result of Reference Example 4A, FIG. 6B shows the result of Reference Example 4B, and FIG. 6C shows the result of Example 4.

  First, in Reference Example 4A, the capacitance value of the grounding capacitor 24 is as low as 0.03 μF. Therefore, as shown in FIG. 6A, the commercial frequency leakage current is small, but the harmonic leakage current is large. In Reference Example 4B, the capacitance value of the grounding capacitor 24 is as high as 0.3 μF. Therefore, as shown in FIG. 6B, the harmonic leakage current is small, but the commercial frequency leakage current is large.

  On the other hand, Example 4 shows that both the commercial frequency leakage current and the harmonic leakage current are small as shown in FIG. 6C. That is, in Example 4, since the coil 30 is connected in parallel to the grounding capacitor 24, the commercial frequency leakage current can be reduced even if the capacitance value of the grounding capacitor 24 is increased to 0.3 μF. It can be seen that the commercial frequency leakage current can be reduced without impairing the noise attenuation effect of the capacitor 24.

[Fifth Experimental Example]
In the fifth experimental example, the magnetic saturation of the magnetic body 26 of the common mode coils 20a to 20c due to the harmonic leakage current was confirmed for Example 5 and Reference Example 5.

  In Example 5, in the first noise filter device 10A described above, the inductance value of each of the common mode coils 20a to 20c was 500 μH, and the capacitance value of the grounding capacitor 24 was 0.3 μF. Further, the inductance value of the coil 30 was adjusted so that the coil 30 and the ground capacitor 24 resonate in parallel at a frequency of 50 Hz.

  In Reference Example 5, in Example 5 described above, the coil 30 was removed, and the capacitance value of the grounding capacitor 24 was set to 0.03 μF.

  The results are shown in FIGS. 7A and 7B. FIG. 7A shows the results (BH characteristics) of Reference Example 5, and FIG. 7B shows the results (BH characteristics) of Example 5. In FIGS. 7A and 7B, areas indicated by Za and Zb indicate BH characteristics when the power is turned on.

  In Reference Example 5, as shown in FIG. 7A, the magnetic field strength at the saturation magnetic flux density is Ha (A / m), and the capacitance value of the ground capacitor 24 is as small as 0.03 μF. There is a problem that the high-frequency leakage current flowing through the coil is small, the amplitude of the harmonic current (common mode component current) leaking to the power supply system is large, and the magnetic bodies 26 of the common mode coils 20a to 20c are likely to be magnetically saturated.

  On the other hand, in Example 5, the magnetic field strength at the saturation magnetic flux density is as low as Hb (A / m), which is about ½ of Reference Example 5, and the capacitance value of the grounding capacitor 24 is as large as 0.3 μF. Therefore, the harmonic leakage current flowing through the grounding capacitor 24 increases, and as a result, the amplitude of the harmonic current (current of the common mode component) leaking to the power supply system decreases, and the magnetic body 26 of the common mode coils 20a to 20c. The problem of magnetic saturation does not occur. That is, Example 5 also brings about the effect that the magnetic saturation of the magnetic body 26 of the common mode coils 20a to 20c can be prevented.

  Next, as shown in FIG. 8, the noise filter device according to the second embodiment (hereinafter referred to as the second noise filter device 10B) has substantially the same configuration as the first noise filter device 10A described above. However, it differs in the following points.

  That is, the second noise filter device 10B includes the same number of ground capacitors (first ground capacitor 24a to third ground capacitor 24c) and coils (first coil 30a to third coil 30c) as the number of power supply lines 18a to 18c. Have Specifically, the first ground capacitor 24a is connected between the first power supply line 18a and the ground GND, the second ground capacitor 24b is connected between the second power supply line 18b and the ground GND, and the third power supply line 18c and the ground GND. A third grounding capacitor 24c is connected between the GNDs. Further, the first coil 30a is connected in parallel to the first ground capacitor 24a, the second coil 30b is connected in parallel to the second ground capacitor 24b, and the third coil 30c is connected in parallel to the third ground capacitor 24c. The first coil 30a to the third coil 30c constitute a second compensation circuit 28B that reduces the leakage current of the commercial frequency component.

  The second noise filter device 10B has a larger number of parts than the first noise filter device 10A described above, but, like the first noise filter device 10A, the leakage current of the commercial frequency component from the AC power source 12 is reduced. Since the second compensation circuit 28B is reduced, the commercial frequency leakage current can be reduced without impairing the attenuation effect of the common mode noise.

  Further, since the capacitances of the first ground capacitor 24a to the third ground capacitor 24c can be increased, the inductance of the common mode coils 20a to 20c can be reduced, and the common mode coils 20a to 20c and the magnetic body can be reduced. The volume occupied by 26 can be reduced. As a result, an inexpensive and small noise filter device can be obtained.

  Next, as shown in FIG. 9, the noise filter device according to the third embodiment (hereinafter referred to as the third noise filter device 10C) has substantially the same configuration as the first noise filter device 10A described above. However, it differs in the following points.

  That is, the AC power supply 12 used in the third noise filter device 10C has a first AC power supply 12A whose power supply frequency is the first commercial frequency (for example, 50 Hz) or a power supply frequency that is the second commercial frequency (for example, 60 Hz). 2 AC power supply 12B. In the third noise filter device 10C, a fourth ground capacitor 24d and a fifth ground capacitor 24e are connected in series between the neutral point 32 of the plurality of line capacitors 22a to 22c and the ground GND.

  Further, the third noise filter device 10C is proportional to the leakage current flowing from the power supply lines 18a to 18c to the ground GND in proportion to the capacitance of the fourth grounding capacitor 24d and the capacitance of the fifth grounding capacitor 24e. The third compensation circuit 28C for reducing the leakage current flowing from the power supply lines 18a to 18c to the ground GND is generated.

  The third compensation circuit 28C has a fourth coil 30d that resonates in parallel with the fourth grounding capacitor 24d at the first commercial frequency (eg, 50 Hz) and a first coil that resonates in parallel with the fifth grounding capacitor 24e at the second commercial frequency (eg, 60 Hz). It has 5 coils 30e. Specifically, the fourth coil 30d is connected in parallel to the fourth ground capacitor 24d, and the fifth coil 30e is connected in parallel to the fifth ground capacitor 24e.

  In the third noise filter device 10C, when the first AC power supply 12A is used as the AC power supply 12, the leakage current of the first commercial frequency component by the first AC power supply 12A is reduced through the third compensation circuit 28C. Can do. Similarly, when the second AC power supply 12B is used as the AC power supply 12, the leakage current of the second commercial frequency component by the second AC power supply 12B can be reduced through the third compensation circuit 28C. This is suitable when it is desired to share the first commercial frequency and the second commercial frequency as the commercial frequency of the AC power supply 12.

[Sixth experimental example]
Here, the sixth experimental example will be described with reference to FIG. In the sixth experimental example, the change in impedance with respect to the frequency was confirmed for Example 6.

  In the sixth embodiment, in the above-described third noise filter device 10C, the inductance values of the common mode coils 20a to 20c are each 500 μH, and the capacitance values of the fourth ground capacitor 24d and the fifth ground capacitor 24e are both 0.3 μF. did. Further, the inductance value of the fourth coil 30d was adjusted so that the fourth coil 30d and the fourth grounding capacitor 24d resonate in parallel at the first commercial frequency of 50 Hz. Similarly, the inductance value of the fifth coil 30e was adjusted so that the fifth coil 30e and the fifth grounding capacitor 24e resonate in parallel at the second commercial frequency of 60 Hz.

  The results are shown in FIG. In FIG. 10, the characteristics of Example 6 are indicated by a solid line L6. The broken line S1A and the alternate long and short dash line S1B indicate the characteristics of Reference Example 1A and Reference Example 1B used in the first experimental example described above for reference.

  In the sixth embodiment, the fourth coil 30d is connected in parallel to the fourth grounding capacitor 24d, and the fifth coil 30e is connected in parallel to the fifth grounding capacitor 24e. Therefore, the impedance of the noise band frequency is 1A. And 1B. On the other hand, each impedance of the 1st commercial frequency and the 2nd commercial frequency is higher than reference example 1B (refer to dashed-dotted line S1B). Therefore, Example 6 has a large noise attenuation effect, and the leakage currents of the first commercial frequency and the second commercial frequency are reduced as compared with the case of Reference Example 1B.

  As described above, the noise filter device according to the sixth embodiment reduces the leakage currents of the first commercial frequency and the second commercial frequency without impairing the noise attenuation effect by the fourth ground capacitor 24d and the fifth ground capacitor 24e. You can see that

  Next, as shown in FIG. 11, the noise filter device according to the fourth embodiment (hereinafter referred to as a fourth noise filter device 10D) has substantially the same configuration as the third noise filter device 10C described above. However, it differs in the following points.

  That is, the fourth noise filter device 10 </ b> D is a device applied when there is a distortion component in the frequency of the AC power supply 12 (power supply frequency).

  In the fourth noise filter device 10D, a sixth grounding capacitor 24f and a seventh grounding capacitor 24g are connected in series between the neutral point 32 of the plurality of line capacitors 22a to 22c and the ground GND.

  The fourth noise filter device 10D is proportional to the leakage current flowing from the power supply lines 18a to 18c to the ground GND in proportion to the capacitance of the sixth grounding capacitor 24f and the capacitance of the seventh grounding capacitor 24g. The fourth compensation circuit 28D for reducing the leakage current flowing from the power supply lines 18a to 18c to the ground GND is generated.

  The fourth compensation circuit 28D includes a sixth coil 30f that resonates in parallel with the sixth grounding capacitor 24f at the commercial frequency (for example, 50 Hz) of the AC power supply 12, and a seventh resonance that resonates in parallel with the seventh grounding capacitor 24g with a distortion component of the commercial frequency. A coil 30g. Specifically, the sixth coil 30f is connected in parallel to the sixth grounding capacitor 24f, and the seventh coil 30g is connected in parallel to the seventh grounding capacitor 24g. In this case, it is preferable to measure the distortion component of the power supply frequency in advance and adjust the inductance value of the seventh coil 30g so that the seventh coil 30g and the seventh grounding capacitor 24g resonate in parallel with the distortion component. .

  In the fourth noise filter device 10D, the leakage current of the commercial frequency component due to the AC power supply 12 can be reduced through the sixth ground capacitor 24f and the sixth coil 30f of the fourth compensation circuit 28D. Similarly, the leakage current of the distortion component due to the AC power supply 12 can be reduced through the seventh grounding capacitor 24g and the seventh coil 30g of the fourth compensation circuit 28D. This is suitable when the commercial frequency has a distortion component as the power supply frequency of the AC power supply 12.

[Seventh experimental example]
Here, the seventh experimental example will be described with reference to FIG. In the seventh experimental example, the change in impedance with respect to the frequency was confirmed for Example 7.

  In the seventh embodiment, in the above-described fourth noise filter device 10D, the inductance values of the common mode coils 20a to 20c are 500 μH, and the capacitance values of the sixth ground capacitor 24f and the seventh ground capacitor 24g are both 0.3 μF. did. Further, the inductance value of the sixth coil 30f was adjusted so that the sixth coil 30f and the sixth grounding capacitor 24f resonate in parallel at a commercial frequency of 50 Hz. Similarly, the inductance value of the seventh coil 30g was adjusted so that the seventh coil 30g and the seventh grounding capacitor 24g resonate in parallel at a distortion component of 250 Hz.

  The results are shown in FIG. In FIG. 12, the characteristic of Example 7 is indicated by a solid line L7. The broken line S1A and the alternate long and short dash line S1B indicate the characteristics of Reference Example 1A and Reference Example 1B used in the first experimental example described above for reference.

  In the seventh embodiment, the sixth coil 30f is connected in parallel to the sixth grounding capacitor 24f, and the seventh coil 30g is connected in parallel to the seventh grounding capacitor 24g. Therefore, the impedance of the noise band frequency is 1A. And 1B. On the other hand, each impedance of the commercial frequency and its distortion component is higher than that of Reference Example 1B (see the alternate long and short dash line S1B). Therefore, Example 7 has a large noise attenuation effect, and the leakage current of the commercial frequency and its distortion component is reduced as compared with the case of Reference Example 1B.

  As described above, the noise filter device according to the seventh embodiment can reduce the leakage current of the commercial frequency and its distortion component without impairing the noise attenuation effect by the sixth grounding capacitor 24f and the seventh grounding capacitor 24g. I understand.

  Next, a noise filter device according to a fifth embodiment (hereinafter referred to as a fifth noise filter device 10E) will be described with reference to FIG.

  As shown in FIG. 13, the fifth noise filter device 10E has substantially the same configuration as the first noise filter device 10A described above, but is configured on the assumption that one or more noise filters 16 are connected. ing.

  That is, one specific noise filter 16 includes the fifth compensation circuit 28E. The fifth compensation circuit 28E is proportional to the capacitance of the eighth grounding capacitor 24h of the noise filter 16 and is generated in proportion to the number of noise filters 16 connected to the AC power supply 12. Leakage current (commercial frequency leakage current by the AC power supply 12) flowing from the ground to the ground GND is reduced. Specifically, an eighth coil 30h that resonates in parallel with the eighth grounding capacitor 24h at the frequency of the AC power supply 12 with respect to the leakage current flowing from the power supply lines 18a to 18c to the ground GND.

  Further, the eighth coil 30h has, for example, three taps (first tap 34a to third tap 34c) in the middle of winding. The fifth compensation circuit 28E includes switching means 36 that varies the inductance value of the eighth coil 30h by switching taps according to the number of noise filters connected to the AC power supply 12. Examples of the switching means 36 include an electrically operated switch and a manually operated switch. The switching means 36 includes, for example, a movable contact 38 connected between the neutral point 32 of the line capacitors 22a to 22c and the eighth ground capacitor 24h, and a fixed contact (halfway connected to the eighth coil 30h). The first tap 34a to the third tap 34c) can be configured.

  The connection of the first tap 34a to the third tap 34c to the eighth coil 30h may be performed as follows, for example. For example, when the movable contact 38 is connected to the first tap 34a by the switching means 36, the inductance value of the eighth coil 30h becomes the maximum value, and when the movable contact 38 is connected to the third tap 34c, the eighth coil The inductance value of 30h is the minimum value. When the movable contact 38 is connected to the second tap 34b, the inductance value of the eighth coil 30h is an intermediate value between the maximum value and the minimum value. Of course, you may connect a tap according to another rule.

  As shown in FIG. 13, when only one noise filter 16 is connected, that is, only a specific noise filter 16 is connected, the movable contact 38 of the switching means 36 is connected to the third tap 34c. Further, as shown in FIG. 14, when only two noise filters 16 are connected, the movable contact 38 of the switching means 36 is connected to the second tap 34b. Similarly, as shown in FIG. 15, when three noise filters 16 are connected, the movable contact 38 of the switching means 36 is connected to the first tap 34a.

  Thus, in the fifth noise filter device 10E, not only when one noise filter 16 is connected to the AC power supply 12, but also when a plurality of noise filters 16 are connected, the attenuation effect of the common mode noise is not impaired. In addition, the commercial frequency leakage current can be reduced.

  Further, since the capacitance of the eighth grounding capacitor 24h can be increased, the inductance of the common mode coils 20a to 20c can be reduced, and the volume occupied by the common mode coils 20a to 20c and the magnetic body 26 can be reduced. can do. As a result, an inexpensive and small noise filter device can be obtained.

  In the example described above, the fifth compensation circuit 28E is configured according to the first compensation circuit 28A. However, the fifth compensation circuit 28E is configured according to any one of the second compensation circuit 28B to the fourth compensation circuit 28D. May be. In any configuration, there is no change in that a plurality of taps are provided and the taps are switched according to the number of noise filters 16 connected to the AC power supply 12.

  Next, the power supply line filter device 100 according to the present embodiment will be described with reference to FIG.

  As shown in FIG. 16, the power line filter device 100 is connected to power lines 18 a to 18 c that are wired from the AC power supply 12 into a specific room 102 (shield room or anechoic chamber).

  The power line filter device 100 includes a metal housing 104 in which the noise filter 16 and the compensation circuit 28 are built.

  The noise filter 16 includes, for example, the common mode coils 20a to 20c connected to the three power supply lines 18a to 18c of the AC power supply 12 and the three power supply lines 18a to 18c, similarly to the first noise filter device 10A described above. And three line capacitors 22a to 22c that are star-connected to each other, and one ground capacitor 24 connected between the three power supply lines 18a to 18c and the ground GND.

  Similar to the first compensation circuit 28A described above, for example, the compensation circuit 28 responds to the leakage current flowing from the power supply lines 18a to 18c to the ground GND in proportion to the capacitance of the ground capacitor 24. And a coil 30 that resonates in parallel with the grounding capacitor 24.

  In this power line filter device 100, a coil 30 having an inductance value that resonates with the power frequency is connected in parallel to the capacitance value of the grounding capacitor 24, so that the attenuation effect of common mode noise is not impaired. Frequency leakage current can be reduced.

  Further, since the capacitance of the grounding capacitor 24 can be increased, the inductance values of the common mode coils 20a to 20c can be reduced, and the volume occupied by the common mode coils 20a to 20c and the magnetic body 26 can be reduced. be able to. As a result, an inexpensive and small power line filter device can be obtained.

  In the above-described example, a noise filter having the same configuration as the noise filter 16 of the first noise filter device 10A is used as the noise filter 16, but any of the second noise filter device 10B to the fifth noise filter device 10E is used. A noise filter having the same configuration as that of the noise filter 16 may be employed.

  As for the compensation circuit 28, the compensation circuit having the same configuration as that of the first compensation circuit 28A is used in the above-described example, but any one of the second compensation circuit 28B to the fifth compensation circuit 28E may be employed. Good.

  Of course, the noise filter device and the power line filter device according to the present invention are not limited to the above-described embodiments, and various configurations can be adopted without departing from the gist of the present invention.

10A to 10E ... 1st noise filter device to 5th noise filter device 12 ... AC power supply 14 ... Power conversion device 16 ... Noise filter 18a to 18c ... Power supply lines 20a to 20c ... Common mode coils 22a to 22c ... Line capacitor 24 ... Grounding capacitor 26 ... Magnetic body 28 ... Compensation circuits 28A to 28E ... First compensation circuit to fifth compensation circuit 30 ... Coil 32 ... Neutral points 34a to 34c ... First tap to third tap 36 ... Switching means 38 ... Moving contact DESCRIPTION OF SYMBOLS 100 ... Power supply line filter apparatus 102 ... Room 104 ... Case GND ... Ground (ground) ia ... Commercial frequency leakage current ib ... Harmonic leakage current

Claims (2)

A noise filter device having a noise filter connected between a power source and a power conversion device in which one phase is a ground phase,
A common mode coil connected to a plurality of power lines between the power source and the power converter;
A plurality of line-to-line capacitors star-connected to the plurality of power supply lines;
At least one grounding capacitor connected between the power line and ground;
Possess a compensating circuit for reducing the leakage current of the commercial frequency component by the power supply,
The compensation circuit includes:
A coil that resonates in parallel with the grounding capacitor at the frequency of the power supply, with respect to the leakage current flowing from the power supply line to the ground generated in proportion to the capacitance of the grounding capacitor;
Having the same number of the grounding capacitors and the coils as the number of the plurality of power supply lines,
The grounding capacitor is connected between each power line and the ground,
The noise filter device, wherein the coil constituting the compensation circuit is connected to each ground capacitor . A noise filter device having a noise filter connected between a power source and a power conversion device in which one phase is a ground phase,
A common mode coil connected to a plurality of power lines between the power source and the power converter;
A plurality of line-to-line capacitors star-connected to the plurality of power supply lines;
Having at least one grounding capacitor connected between the power line and ground;
One or more noise filters are connected to the power source;
At least one of the noise filters includes a compensation circuit that reduces a leakage current of a commercial frequency component due to the power source,
The compensation circuit includes:
With respect to the leakage current flowing from the power line to the ground that is proportional to the capacitance of the ground capacitor of one noise filter and proportional to the number of the noise filters connected to the power source, A coil that resonates in parallel with the grounded capacitor at the frequency of the power source;
The coil has a plurality of taps;
The compensation circuit includes a switching unit that changes an inductance value of the coil by switching the tap according to the number of the noise filters connected to the power source.

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