JP2006136058A - Noise filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a noise filter that can suppress EMI noise, can reduce a leak current and can be reduced in size. <P>SOLUTION: The noise filter suppresses the EMI noise generated at power converters 1, 2 and 3, and comprises: a common mode transformer 8 composed of a primary winding that is connected in series to a power supply line at the input side of the power converter, and a secondary winging electromagnetically connected to the primary winding; a capacitor 9 connected between both terminals of the secondary winding of the common mode transformer; and grounding capacitors 7a, 7b and 7c connected between the ground and the power supply line that connects the common mode transformer and the power converter. The noise filter sets a resonance frequency generated by an LC parallel resonance circuit composed of the secondary winding of the common mode transformer and the capacitor in a frequency band of common mode noise. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a noise filter for suppressing leakage current and EMI noise generated by a switching operation of a switching element included in a power converter.

  For example, a power conversion device such as an inverter or a converter generates EMI noise due to a high-speed switching operation of a switching element incorporated therein. This EMI noise may adversely affect, for example, conduction to other devices having a common power supply and malfunction. For this reason, the EMI noise is regulated, and the EMI noise generated by the apparatus needs to satisfy this regulation value. Therefore, conventionally, a countermeasure is provided by providing a noise filter on the input side of the power converter (see, for example, Non-Patent Document 1).

  FIG. 7 is a circuit diagram showing the configuration of the most common noise filter that reduces common mode noise. Here, a case where the motor 4 is driven using an inverter device including the converter 1, the inverter 2, and the smoothing capacitor 3 will be described as an example.

  A high-frequency common mode current generated by switching the elements of the inverter 2 reaches the motor 4 through the power line, and flows to the ground through the stray capacitance of the winding of the motor 4. When there is no noise filter, this common mode current returns from the ground to the power source 5 and returns to the inverter device. The common mode current flowing through the power supply 5 is observed as a common mode EMI noise (ie, common mode noise) as a result.

  On the other hand, consider a case where a noise filter composed of the common mode choke coil 6 and the ground capacitors 7a, 7b, 7c is attached between the power source 5 and the inverter device. The common mode choke coil 6 exhibits a large impedance with respect to a common mode current that is a high-frequency component flowing through the power supply line, and conversely, the impedance of the path formed by the ground capacitors 7a, 7b, and 7c is low. As a result, the common mode current flowing from the motor 4 to the ground returns to the inverter device through the grounded capacitors 7a, 7b and 7c having low impedance, and the EMI noise in the power source 5 is reduced.

As a related technique, Patent Document 1 discloses a power conversion device including a common mode transformer for reducing a common mode current (leakage current) generated by a voltage type inverter. This power changing device is composed of a rectifier, a common mode transformer, an inverter, and the like, and the common mode transformer is connected to the DC side of the inverter. With this configuration, since the number of conducting wires wound around the window portion of the core of the common mode transformer can be reduced, the window area can be made smaller than before, and the volume of the common mode transformer can be reduced.
Yasutaka Shimizu and Yuki Sugiura, "Basics and Countermeasures for Electromagnetic Interference", The Institute of Electronics, Information and Communication Engineers, September 20, 1995, page 193 JP 2003-174777 A

  Incidentally, the impedance of the common mode choke coil 6 constituting the noise filter shown in FIG. 7 increases as the frequency increases, and the impedance of the ground capacitors 7a, 7b, and 7c decreases. For this reason, the configuration of the conventional so-called L-type filter is very effective for reducing noise of higher frequency components. However, for example, a large noise reduction effect is obtained for low-frequency noise of several hundred kHz or less. I can't.

  Therefore, when trying to suppress noise in the low frequency band, a common mode choke coil with a large inductance and a large capacitance grounding capacitor are required, and an increase in the size of the filter cannot be avoided. The filter performance is over-spec.

  Furthermore, when the capacity of the grounding capacitor is increased, another adverse effect of increasing the leakage current from the power source or the inverter to the ground is caused.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a noise filter that can suppress EMI noise and can reduce the leakage current, and can be downsized.

  In order to solve the above problems, a noise filter according to a first aspect of the present invention is a noise filter that suppresses EMI noise generated in a power converter, and is inserted in series in a power line on the input side of the power converter. A common mode transformer comprising a primary winding and a secondary winding electromagnetically coupled to the primary winding, a capacitor connected between both terminals of the secondary winding of the common mode transformer, and a common mode It has a grounding capacitor connected between the power line connecting the transformer and the power converter and the ground, and the resonance frequency by the LC parallel resonance circuit formed by the secondary winding of the common mode transformer and the capacitor is set to the common mode. The frequency band of noise is set.

  A noise filter according to a second invention is the noise filter according to the first invention, further comprising a common mode choke coil inserted in series in a power line on the input side of the power converter.

  According to a third aspect of the present invention, there is provided a noise filter according to the first or second aspect of the present invention, wherein the power line and the ground are arranged so that at least one of the common mode transformer and the common mode choke coil is sandwiched by a ground capacitor. And another grounding capacitor connected between the two.

  A noise filter according to a fourth aspect of the present invention is a converter that converts AC power from an input-side power line into DC power and outputs the DC power to a power line on the output side of the converter, and converts the DC power output from the converter into AC power. A noise filter that suppresses EMI noise generated in a power conversion device that includes an inverter that converts the signal into an output power line and outputs the power to the output power line, the primary winding inserted in series in the power line, and the A common mode transformer comprising a secondary winding that is electromagnetically coupled to the primary winding, a capacitor connected between both terminals of the secondary winding of the common mode transformer, a common mode transformer, a power line, and a ground. With a grounded capacitor connected between them, and common resonance frequency by LC parallel resonance circuit formed by secondary winding of common mode transformer and capacitor And setting the frequency band of mode noise.

  A noise filter according to a fifth invention is the noise filter according to the fourth invention, further comprising a common mode choke coil inserted in series with the power supply line.

  A noise filter according to a sixth aspect of the present invention is the noise filter according to the fourth aspect or the fifth aspect, wherein the power line and the ground are arranged so that at least one of the common mode transformer and the common mode choke coil is sandwiched between ground capacitors. A second grounding capacitor connected between the two is provided.

  A noise filter according to a seventh aspect of the present invention is the noise filter according to any of the fourth to sixth aspects of the present invention, and is any one of a common mode transformer, a ground capacitor, a common mode choke coil, and a second ground capacitor. Is connected to the power supply line on the output side of the converter.

  A noise filter according to an eighth aspect of the present invention is a converter that converts AC power from an input-side power line into DC power and outputs the DC power to a power line on the output side of the converter, and converts the DC power output from the converter into AC power. A noise filter that suppresses EMI noise generated in a power conversion device that includes an inverter that converts the signal into an output power line and outputs the power to the output power line, the primary winding inserted in series in the power line, and the A common mode transformer comprising a secondary winding that is electromagnetically coupled to the primary winding, a capacitor connected between both terminals of the secondary winding of the common mode transformer, and a plurality connected in series between the phases of the power line And a grounding capacitor connected between the neutral point of the plurality of interphase capacitors and the ground, and from the secondary winding and the capacitor of the common mode transformer The resonance frequency due to the LC parallel resonance circuit made and sets the frequency band of the common mode noise.

  A noise filter according to a ninth aspect is the noise filter according to the eighth aspect, further comprising a common mode choke coil inserted in series with the power supply line.

  A noise filter according to a tenth invention is the noise filter according to the eighth invention or the ninth invention, wherein at least one of the common mode transformer and the common mode choke coil is sandwiched between the interphase capacitor and the ground capacitor. A plurality of second interphase capacitors connected in series between the two phases, and a second grounding capacitor connected between a neutral point of the plurality of second interphase capacitors and the ground.

  A noise filter according to an eleventh aspect of the present invention is the noise filter according to any of the eighth aspect to the tenth aspect of the present invention, and is any one of a common mode transformer, an interphase capacitor, a common mode choke coil, and a second interphase capacitor. Is connected to the power supply line on the output side of the converter.

  According to the noise filter according to the first aspect of the invention, the impedance observed at both ends of the common mode transformer becomes high at the resonance frequency by the LC parallel resonance circuit composed of the secondary winding of the common mode transformer and the capacitor. Since the resonance frequency at which the impedance is increased is set in the frequency band of common mode noise, by appropriately selecting the inductance of the secondary winding and the capacitance of the capacitor, for example, for low frequency common mode noise of several hundred kHz or less. Large noise reduction effect. As a result, since it is not necessary to use a common mode choke coil having a large inductance, the common mode transformer can be made significantly smaller than a common mode choke coil that has been used in the past, and thus the size of the noise filter can be reduced.

  According to the noise filter of the second invention, in the frequency band higher than the resonance frequency, the common mode noise flowing around the capacitor whose impedance is low can be blocked by the common mode choke coil. Mode noise can be filtered.

  According to the noise filter of the third invention, noise is removed by the multistage LC filter formed by any combination of a common mode transformer or common mode choke coil and a ground capacitor or other ground capacitor. The reduction effect is further increased. In addition, when obtaining equivalent characteristics, dividing the grounded capacitor in two stages can reduce the total capacitor capacity and also reduce the inductance of the common mode transformer and common mode choke coil, thus reducing the size of the noise filter. it can. Furthermore, since the total capacity of the grounding capacitor is reduced, the leakage current flowing through the grounding capacitor can be reduced.

  According to the noise filter of the fourth invention, the common mode transformer, common mode coil, and grounding capacitor that existed in the first to third inventions were connected in three phases, whereas the converter and By connecting to the inverter in a single phase, the number of windings of the common mode transformer and common mode choke coil can be reduced, and the number of grounding capacitors can be reduced.

  According to the noise filter according to the fifth invention, the same effect as that of the noise filter according to the second invention can be obtained. According to the noise filter according to the sixth aspect of the invention, the same effect as that of the noise filter according to the third aspect of the invention can be obtained.

  According to the noise filter of the seventh aspect of the present invention, any one of the common mode transformer, the ground capacitor, the common mode choke coil, and the second ground capacitor is connected to the power line on the output side of the converter. The effect of the noise filter according to the invention can be obtained.

  According to the noise filter of the eighth invention, since the number of grounding capacitors is reduced by using interphase capacitors that can be reduced in shape as compared with the grounding capacitor, further miniaturization is possible. Further, since the potential difference between the neutral point and the ground is small, a low-voltage grounding capacitor can be used, so that an inexpensive noise filter can be configured. Furthermore, since the interphase capacitor also acts on normal mode noise, it is possible to reduce normal mode noise in addition to common mode noise.

  According to the noise filter according to the ninth aspect, the same effect as that of the noise filter according to the second aspect can be obtained.

  According to the noise filter according to the tenth aspect of the present invention, since the plurality of second interphase capacitors and the second grounding capacitor are further provided, it is not necessary to increase the capacity of the plurality of interphase capacitors. Can be configured at low cost.

  According to the noise filter of the eleventh aspect of the present invention, any one of the common mode transformer, the interphase capacitor, the common mode choke coil, and the second interphase capacitor is connected to the power line on the output side of the converter, so that the common mode The number of windings of the transformer and common mode choke coil can be reduced, and the number of interphase capacitors and second phase capacitors can be reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the same or corresponding components will be described with the same reference numerals. Moreover, an inverter apparatus shall be used as a power converter device.

  FIG. 1 is a diagram illustrating a configuration of a drive circuit that drives a load using an inverter device to which a noise filter according to a first embodiment of the present invention is applied.

  The inverter device includes a converter 1, an inverter 2 and a smoothing capacitor 3. The input terminal of the converter 1 is connected to the power source 5 via a common mode transformer 8 and a power line which will be described later. The output terminal of the converter 1 is connected to the input terminal of the inverter 2. The converter 1 converts AC power supplied from the power source 5 through the power line on the input side and the common mode transformer 8 into DC power and sends it to the inverter 2.

  The input terminal of the inverter 2 is connected to the output terminal of the converter 1 as described above. An output terminal of the inverter 2 is connected to a motor 4 as a load via a power line. The inverter 2 converts the DC power from the converter 1 into AC power, and supplies the AC power to the motor 4 via the power line on the output side. Smoothing capacitor 3 is connected between the output terminals of converter 1 (between the input terminals of inverter 2), and smoothes the DC power output from converter 1.

  The noise filter includes a common mode transformer 8 and ground capacitors 7a, 7b, and 7c.

  The common mode transformer 8 has a structure in which a new winding is added to the common mode choke coil, the common mode choke coil is used as a primary winding, and the newly added winding becomes a primary winding. Used as a secondary winding to be electromagnetically coupled. The primary winding of the common mode transformer 8 is inserted in series in a power supply line connecting the power supply 5 and the converter 1. A capacitor 9 is connected between both terminals of the secondary winding of the common mode transformer 8. The capacitor 9 and the secondary winding of the common mode transformer 8 form an LC parallel resonance circuit.

  One terminal of each of the grounding capacitors 7a, 7b, and 7c is connected to each of three electric wires constituting a power supply line that connects between the common mode transformer 8 and the converter 1, and the other terminal is connected to the ground GND. Yes.

  In the drive circuit configured as described above, the resonance frequency of the excitation inductance L of the secondary winding of the common mode transformer 8 and the capacitance C of the capacitor 9 constituting the LC parallel resonance circuit is desired to reduce the common mode noise most. The frequency band, for example, 150 kHz to several hundred kHz, which is difficult to reduce common mode noise, is selected.

  Thereby, the impedance observed at both ends of the common mode transformer 8 shows a higher impedance than the simple excitation inductance L in the resonance frequency band where the excitation inductance L and the capacitor C resonate in parallel. For this reason, it is possible to effectively reduce noise with a common mode choke coil having a small inductance.

  As described above, according to the noise filter according to the first embodiment, the impedance with respect to the common mode noise in the low frequency band is increased by using the LC parallel resonant circuit including the secondary winding of the common mode transformer 8 and the capacitor 9. Thus, it is not necessary to use a large inductance common mode choke coil. As a result, since the common mode transformer 8 can be made significantly smaller than a common mode choke coil that has been used conventionally, the noise filter can be reduced in size.

  FIG. 2 is a diagram illustrating a configuration of a drive circuit that drives a load using the inverter device to which the noise filter according to the second embodiment of the present invention is applied.

  The noise filter according to the second embodiment has a configuration in which a common mode choke coil 10 is newly inserted in series with the power supply line between the primary winding of the common mode transformer 8 and the converter 1 of the noise filter according to the first embodiment. Has been.

  In the case of the noise filter according to the first embodiment described above, the impedance is lower than the resonance frequency band of the common mode transformer 8 at a level equal to or higher than that of a normal common mode choke coil, but the impedance is low in the frequency band higher than the resonance frequency. The common mode noise flows around the capacitor 9. Therefore, the filtering function in a frequency band higher than the resonance frequency is reduced.

  On the other hand, in the noise filter configured as described above, the common mode choke coil 10 maintains the impedance high in the frequency band (frequency band higher than the resonance frequency) in which the impedance of the common mode transformer 8 decreases. Operate.

  According to the noise filter according to the second embodiment, common mode noise can be filtered in a wider frequency band than the noise filter according to the first embodiment.

  In the drive circuit shown in FIG. 2, the common mode choke coil 10 is connected to the power supply side with respect to the ground capacitors 7a, 7b, and 7c. It can be disposed between the grounding capacitors 7a, 7b and 7c. Conversely, the common mode choke coil 10, the ground capacitors 7 a, 7 b, 7 c and the common mode transformer 8 can be arranged in this order from the power source 5 to the converter 1.

  FIG. 3 is a diagram illustrating a configuration of a drive circuit that drives a load using the inverter device to which the noise filter according to the third embodiment of the present invention is applied.

  The noise filter according to the third embodiment is configured by adding new ground capacitors 11a, 11b, and 11c to the noise filter according to the second embodiment. One terminal of each of the new ground capacitors 11a, 11b, and 11c is connected to a power supply line between the common mode transformer 8 and the common mode choke coil 10, and the other terminal is connected to the ground GND.

  In the drive circuit configured as described above, the first LC filter including the common mode transformer 8 and the ground capacitors 11a, 11b, and 11c, the common mode choke coil 10, and the ground capacitor are provided between the power source 5 and the converter 1. A two-stage filter such as a second LC filter composed of 7a, 7b, and 7c is inserted, and common mode noise that circulates from the motor 4 to the power source 5 is removed by these two-stage filters.

  According to the noise filter according to the third embodiment, since the filter has a multistage configuration, the noise reduction effect is further increased. Further, when obtaining equivalent characteristics, the total capacitor capacity can be reduced and the inductances of the common mode transformer 8 and the common mode choke coil 10 can be reduced by dividing the ground capacitor into two stages. As a result, the noise filter can be reduced in size. Furthermore, since the total capacity of the grounding capacitor is reduced, the leakage current flowing through the grounding capacitor can be reduced.

  In the drive circuit shown in FIG. 3, the common mode transformer 8, the ground capacitors 11a, 11b, and 11c, the common mode choke coil 10, and the ground capacitors 7a, 7b, and 7c are arranged in this order from the power source 5 to the converter 1. However, the arrangement positions of the two sets of the ground capacitors 7a, 7b, and 7c and the ground capacitors 11a, 11b, and 11c are arbitrary as long as they sandwich at least one of the common mode transformer 8 and the common mode choke coil 10. . Further, the common mode transformer 8 and the common mode choke coil 10 can be arranged in reverse.

  FIG. 4 is a diagram illustrating a configuration of a drive circuit that drives a load using an inverter device to which a noise filter according to a fourth embodiment of the present invention is applied.

  The inverter device includes a converter 1, an inverter 2 and a smoothing capacitor 3. The input terminal of the converter 1 is connected to the power supply 5 through a power supply line. The output terminal of the converter 1 is connected to the input terminal of the inverter 2 via a common mode transformer 13 and a common mode choke coil 14 which will be described later. The converter 1 converts AC power supplied from the power source 5 through the power line on the input side into DC power, and supplies the DC power to the inverter 2 via the common mode transformer 13 and the common mode choke coil 14.

  The input terminal of the inverter 2 is connected to the output terminal of the converter 1 via the common mode transformer 13 and the common mode choke coil 14 as described above. An output terminal of the inverter 2 is connected to a motor 4 as a load via a power line. The inverter 2 converts the DC power supplied from the converter 1 through the common mode transformer 13 and the common mode choke coil 14 into AC power, and supplies the AC power to the motor 4 through the power line on the output side. Smoothing capacitor 3 is connected between the input terminals of inverter 2 and smoothes the DC power supplied from converter 1 via common mode transformer 13 and common mode choke coil 14.

  The noise filter includes a common mode transformer 13, ground capacitors 15a and 15b, a common mode choke coil 14, and ground capacitors 16a and 16b.

  The common mode transformer 13 has a structure in which a new winding is added to the common mode choke coil, the common mode choke coil is used as a primary winding, and the newly added winding is used as a secondary winding. used. The primary winding of the common mode transformer 13 is inserted in series in a DC line from the converter 1 to the common mode choke coil 14. A capacitor 12 is connected between both terminals of the secondary winding of the common mode transformer 13. The capacitor 12 and the secondary winding of the common mode transformer 13 form an LC parallel resonance circuit.

  One terminal of each of the grounding capacitors 15a and 15b is connected to the two electric wires constituting the DC line between the common mode transformer 13 and the common mode choke coil 14, and the other terminal is connected to the ground GND. Yes.

  The common mode choke coil 14 is inserted in series in a DC line extending from the common mode transformer 13 to the inverter 2. One terminal of each of the ground capacitors 16a and 16b is connected to two electric wires constituting a DC line between the common mode choke coil 14 and the inverter 2, and the other terminal is connected to the ground.

  In the noise filter configured as described above, the first LC filter including the common mode transformer 13 and the ground capacitors 15a and 11b between the converter 1 and the inverter 2, the common mode choke coil 14, the ground capacitor 16a, A two-stage filter such as a second LC filter composed of 16b is inserted, and common mode noise that circulates from the motor 4 to the power source 5 is removed by these two-stage filters.

  According to the noise filter according to the fourth embodiment, since the subsequent stage of the converter 1 is a single phase, the number of windings of the common mode transformer 13 and the common mode choke coil 14 is reduced by one compared to the case of the three phases. be able to. According to this configuration, since the current per phase increases as compared with the noise filters according to the first to third embodiments, the diameter of the electric wire constituting the DC line is somewhat increased, but the number of phases is decreased. Therefore, it is possible to downsize the structure. In addition, the number of grounding capacitors can be reduced by the amount of phase reduction.

  Note that the noise filter according to the fourth embodiment is configured such that the two-stage filters such as the first LC filter and the second LC filter are arranged between the converter 1 and the inverter 2 as described above. Similar to Example 1, only the first LC filter can be arranged between the converter 1 and the inverter 2. Further, similarly to the second embodiment, a common mode choke coil 14 may be added to the first LC filter and disposed between the converter 1 and the inverter 2. Further, any one of the common mode transformer 13, the ground capacitors 16 a and 16 b, the common mode choke coil 14, and the ground capacitors 15 a and 15 b may be connected to the power line on the output side of the converter 1.

  FIG. 5 is a diagram illustrating a configuration of a drive circuit that drives a load using an inverter device to which a noise filter according to a fifth embodiment of the present invention is applied.

  In the filter according to the fifth embodiment, instead of the ground capacitors 15a and 15b of the filter according to the fourth embodiment, the DC lines are connected by interphase capacitors 17a and 17b connected in series, and are formed by interphase capacitors 17a and 17b. The neutral point of the DC voltage and the ground GND are connected by a grounding capacitor 19. Further, in place of the ground capacitors 16a and 16b of the filter according to the fourth embodiment, the DC lines are connected by interphase capacitors 18a and 18b connected in series, and the neutrality of the DC voltage formed by the interphase capacitors 18a and 18b. The point and the ground GND are connected by the grounding capacitor 20.

  In the noise filter configured as described above, between the converter 1 and the inverter 2, the first LC filter including the common mode transformer 13, the interphase capacitors 17 a and 17 b, and the ground capacitor 19, the common mode choke coil 14, A two-stage filter such as a second LC filter composed of interphase capacitors 18a and 18b and a ground capacitor 20 is inserted, and common mode noise that goes from the motor 4 to the power source 5 is removed by these two-stage filters.

  The noise filter according to the fifth embodiment has the following advantages. That is, the shape of the grounding capacitor is generally considerably larger than the interphase capacitor when compared with the same capacity due to the difference in safety standards. In the noise filter according to the fifth embodiment, the size of the large grounding capacitor is only half that of the noise filter according to the fourth embodiment, so that the size can be further reduced. In addition, since the potential difference between the neutral point and the ground GND is small, a low-voltage capacitor can be used, so that an inexpensive noise filter can be configured. Furthermore, since the interphase capacitor also acts on normal mode noise, it is possible to reduce normal mode noise in addition to common mode noise.

  The noise filter according to the fifth embodiment is configured such that the two-stage filters such as the first LC filter and the second LC filter are arranged between the converter 1 and the inverter 2 as described above. Similar to Example 1, only the first LC filter can be arranged between the converter 1 and the inverter 2. Further, similarly to the second embodiment, a common mode choke coil 14 may be added to the first LC filter and disposed between the converter 1 and the inverter 2. Further, any one of the common mode transformer 13, the interphase capacitors 18a and 18b, the common mode choke coil 14, and the interphase capacitors 17a and 17b may be connected to the power line on the output side of the converter 1.

  FIG. 6 is a diagram illustrating a configuration of a drive circuit that drives a load using an inverter device to which a noise filter according to a sixth embodiment of the present invention is applied.

  In the filter according to the sixth embodiment, an interphase capacitor 21 is additionally connected to the DC line that is the output of the converter 1 of the filter according to the fifth embodiment, and the input side power line (the power line between the power source 5 and the converter 1) is further connected. ) Are additionally connected to interphase capacitors 22a, 22b, and 22c.

  The drive circuit configured as described above has the following advantages. In other words, the interphase capacitors 17a and 17b and the interphase capacitors 18a and 18b forming the neutral point act to reduce the normal mode noise generated from the inverter 2 to some extent, but the two capacitors are connected in series. Therefore, in order to obtain a desired capacitance between the lines, a capacitor having a capacity twice that of the capacitor is required.

  On the other hand, according to the noise filter according to the sixth embodiment, the interphase capacitor 21 is provided in the DC line, and the interphase capacitor 21 is configured to reduce the normal mode noise. There is no need to increase the capacitances of 17a and 17b and interphase capacitors 18a and 18b. As a result, a noise filter can be configured with a minimum capacitor capacity.

  By the way, when the converter 1 is composed of a diode rectifier, the common mode noise generated from the inverter 2 and leaking to the power source through the common mode transformer 13 and the common mode choke coil 14 passes through the diode rectifier. Part of it changes to normal mode noise. This is due to the fact that the diode rectifier is limited to two phases among the three phases on the input side. Interphase capacitors 22a, 22b, and 22c connected to the input side power supply line effectively act to reduce such normal mode noise.

  In the filter according to the sixth embodiment, the interphase capacitor 21 is provided on the output side of the converter 1 and the interphase capacitors 22a, 22b, and 22c are provided on the input side. However, the interphase capacitor 21 or the interphase capacitors 22a, 22b, and 22c are provided. It is also possible to provide only one of these.

  The present invention is applicable to an inverter device including a converter and an inverter.

It is a figure which shows the structure of the drive circuit which drives load using the inverter apparatus to which the noise filter which concerns on Example 1 of this invention was applied. It is a figure which shows the structure of the drive circuit which drives load using the inverter apparatus to which the noise filter which concerns on Example 2 of this invention was applied. It is a figure which shows the structure of the drive circuit which drives load using the inverter apparatus to which the noise filter which concerns on Example 3 of this invention was applied. It is a figure which shows the structure of the drive circuit which drives load using the inverter apparatus to which the noise filter which concerns on Example 4 of this invention was applied. It is a figure which shows the structure of the drive circuit which drives load using the inverter apparatus to which the noise filter which concerns on Example 5 of this invention was applied. It is a figure which shows the structure of the drive circuit which drives load using the inverter apparatus to which the noise filter which concerns on Example 6 of this invention was applied. It is a figure which shows the structure of the drive circuit which drives load using the inverter apparatus to which the conventional noise filter was applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Converter 2 Inverter 3 Smoothing capacitor 4 Motor 5 Power supply 7a-7c, 11a-11c, 15a, 15b, 16a, 16b, 19, 20 Grounding capacitor 8, 13 Common mode transformer 9, 12 Capacitor 10, 14 Common mode choke coil 17a , 17b, 18a, 18b, 21, 22a, 22b, 22c Interphase capacitor

Claims (11)

A noise filter for suppressing EMI noise generated in a power converter,
A common mode transformer comprising a primary winding inserted in series in a power line on the input side of the power converter and a secondary winding electromagnetically coupled to the primary winding;
A capacitor connected between both terminals of the secondary winding of the common mode transformer;
A grounding capacitor connected between a power line connecting the common mode transformer and the power converter and ground,
A noise filter, wherein a resonance frequency of an LC parallel resonance circuit formed by a secondary winding of the common mode transformer and the capacitor is set in a frequency band of common mode noise.   The noise filter according to claim 1, further comprising a common mode choke coil inserted in series in a power line on an input side of the power converter.   2. The apparatus according to claim 1, further comprising another grounding capacitor connected between a power line and ground so that at least one of the common mode transformer and the common mode choke coil is sandwiched by the grounding capacitor. The noise filter according to claim 2. A converter that converts AC power from the power supply line on the input side to DC power and outputs it to the power supply line on the output side of the converter; A noise filter that suppresses EMI noise generated in a power conversion device including an inverter for output,
A common mode transformer comprising a primary winding inserted in series in the power supply line and a secondary winding electromagnetically coupled to the primary winding;
A capacitor connected between both terminals of the secondary winding of the common mode transformer;
A grounding capacitor connected between the common mode transformer, a power supply line, and ground;
A noise filter, wherein a resonance frequency of an LC parallel resonance circuit formed by a secondary winding of the common mode transformer and the capacitor is set in a frequency band of common mode noise.   The noise filter according to claim 4, further comprising a common mode choke coil inserted in series with the power supply line.   5. A second grounding capacitor connected between a power line and ground so that at least one of the common mode transformer and the common mode choke coil is sandwiched by the grounding capacitor. The noise filter according to claim 5.   7. The power supply line on the output side of the converter is connected to any one of the common mode transformer, the ground capacitor, the common mode choke coil, and the second ground capacitor. The noise filter according to any one of the above. A converter that converts AC power from the power supply line on the input side to DC power and outputs it to the power supply line on the output side of the converter; A noise filter that suppresses EMI noise generated in a power conversion device including an inverter for output,
A common mode transformer comprising a primary winding inserted in series in the power supply line and a secondary winding electromagnetically coupled to the primary winding;
A capacitor connected between both terminals of the secondary winding of the common mode transformer;
A plurality of interphase capacitors connected in series between the phases of the power line; and
A grounding capacitor connected between a neutral point of the plurality of interphase capacitors and ground,
A noise filter, wherein a resonance frequency of an LC parallel resonance circuit formed by a secondary winding of the common mode transformer and the capacitor is set in a frequency band of common mode noise.   9. The noise filter according to claim 8, further comprising a common mode choke coil inserted in series with the power supply line.   Between the plurality of second phase capacitors and the plurality of second phases connected in series between the phases of the power supply line so that at least one of the common mode transformer and the common mode choke coil is sandwiched between the phase capacitor and the ground capacitor The noise filter according to claim 8, further comprising a second grounding capacitor connected between a neutral point of the capacitor and the ground. 11. The power supply line on the output side of the converter is connected to any one of the common mode transformer, the interphase capacitor, the common mode choke coil, and the second interphase capacitor. The noise filter according to any one of the above.

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