JP2017055584A - Three-phase noise filter and ac motor driving system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-phase noise filter that can reduce the parasitic inductance between capacitor terminals to enhance the filter performance, and an AC motor driving system using the same.SOLUTION: A three-phase noise filter includes wiring patterns 111 to 113 provided on a substrate, X capacitors 11 to 13 connected between the respective lines of the wiring patterns 111 to 113, and an inductor 50 connected to the wiring patterns 111 to 113. The wiring pattern 112 is provided between the wiring pattern 111 and the wiring pattern 113, and the wiring patterns 111 and 113 each have a bent portion that is bent so as to approach to the wiring pattern 112. The X capacitor 11 is connected to the bent portion of the wiring pattern 111 and the wiring pattern 112, the X capacitor 12 is connected to the wiring pattern 112 and the bent portion of the wiring pattern 113, and the X capacitor 13 is connected to the bent portion of the wiring pattern 113 and the bent portion of the wiring pattern 111.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a three-phase noise filter and an AC motor drive system using the same.

  In a three-phase power converter used for driving an AC motor at a variable speed, AC power of a three-phase system power source is converted into DC power by a converter, and further DC power is converted into AC voltage by an inverter. In such a three-phase power converter, the form of power (DC, AC, voltage, frequency, etc.) is converted by switching a semiconductor switching element such as an IGBT (Insulated Gate Bipolar Transistor). In particular, in order to reduce the heat generation of the semiconductor element, the DC voltage is converted into a pulsed AC voltage by high-speed switching, so that the rise and fall of the pulse have very steep characteristics. Therefore, the switching waveform contains a lot of high frequency components, and an unintended resonance circuit is formed by the parasitic inductance and the parasitic capacitance existing in the main circuit and the power cable, so that common mode noise and normal mode noise increase at high frequencies.

  In order to reduce such noise, a three-phase noise filter is generally used. To reduce the noise inherent in the three-phase power supply and the noise generated by switching of the semiconductor switching elements in the converter and inverter, a three-phase noise filter is connected between the three-phase power supply and the converter. Is done. In addition, when the pulse voltage generated by the inverter is applied to the input terminal of the AC motor, a noise current leaks to the ground through the parasitic capacitance existing between the AC motor and the housing. In order to prevent the leaked noise current from flowing to the three-phase power supply side, the three-phase noise filter has a function of bypassing the noise current and closing it with a converter, an inverter, and an AC motor. Here, when the noise current leaking to the ground via the AC motor is bypassed closer, a three-phase noise filter is connected between the inverter and the AC motor.

  With respect to such a three-phase noise filter, a conventional technique described in Patent Document 1 is known. In this prior art, the three-phase noise filter is composed of an inductor (common mode choke coil) and a capacitor on a printed circuit board. A capacitor for normal mode noise (X capacitor) is provided between each wiring pattern on the input terminal side and output terminal side with respect to the inductor (common mode choke coil), and each wiring pattern and ground pattern are arranged on the output terminal side. A capacitor for common mode noise (Y capacitor) is provided between them. By arranging these electrical components and terminals close to each other and reducing the parasitic inductance on the wiring pattern, the characteristics of the noise filter can be improved.

JP 2001-217668 A

  However, in the three-phase noise filter according to the above-described prior art, each of the two wiring patterns positioned on the outside of the three wiring patterns juxtaposed on the printed circuit board has a gap between the two wiring patterns. In order to connect the X capacitors for the phase, a wiring pattern portion branched from the main wiring pattern portion connecting the terminal and the inductor is provided. For this reason, the wiring length between the terminal of the other X capacitor connected to these two wiring patterns and the terminal of the X capacitor connected to the branched wiring pattern portion becomes large, and between the terminals of each X capacitor. Parasitic inductance exists. FIG. 7 shows a circuit diagram of such a conventional three-phase noise filter including parasitic inductance.

  As shown in FIG. 7, the three-phase noise filter 201 according to the prior art is an L-C type secondary circuit configured by an inductor (common mode choke coil) 50 and Y capacitors 91 to 93 with respect to common mode noise. It becomes a low-pass filter. Further, for normal mode noise, a CLC type composed of X capacitors 11 to 13, a leakage inductance (not shown) of an inductor (common mode choke coil) 50, and X capacitors 21 to 23 is used. A third-order low-pass filter is obtained. The three-phase noise filter 201 includes input terminals 1 to 3 and output terminals 4 to 6 corresponding to a three-phase power supply, and a ground terminal 7 to which one end of a Y capacitor is connected. The parasitic inductance 151 due to the wiring pattern portion between the terminal of the X capacitor 11 and the terminal of the X capacitor 13, the parasitic inductance 152 due to the wiring pattern portion between the terminal of the X capacitor 12 and the terminal of the X capacitor 13, There is a parasitic inductance 153 due to the wiring pattern portion between the terminal and the terminal of the X capacitor 23, and a parasitic inductance 154 due to the wiring pattern portion between the terminal of the X capacitor 22 and the terminal of the X capacitor 23.

  The effect of such parasitic inductance on noise will be described with reference to FIG.

  FIG. 8 is a circuit diagram showing the flow of noise current in the three-phase noise filter according to the prior art. Here, normal mode noise is generated between the R phase (1) and the T phase (3) of the three-phase system power supply.

  The noise current is attenuated by the inductor (common mode choke coil) 50, the X capacitors 11 to 13 and the X capacitors 21 to 23, but the noise current passing through the inductor (common mode choke coil) 50 is connected to the R phase and the T phase. Return to the three-phase system power supply via the X capacitors 21 to 23. A parallel circuit of an X capacitor 23 and a series capacitor of X capacitor 21 and X capacitor 22 is connected between the R phase and the T phase on the output terminal side. For this reason, the noise current is shunted to the X capacitor 23 side (shunt A) and to the series capacitor side (shunt B) of the X capacitor 21 and the X capacitor 22. However, the parasitic inductances 153 and 154 make it difficult for the shunt current (shunt B) to flow to the series capacitor side. Therefore, the filter performance is degraded.

  Therefore, the present invention provides a three-phase noise filter that can improve the filter performance by reducing the parasitic inductance between the capacitor terminals, and an AC motor drive system using the same.

  In order to solve the above-described problems, a three-phase noise filter according to the present invention includes a first wiring pattern, a second wiring pattern, a third wiring pattern, a first wiring pattern, and a second wiring pattern provided on a substrate. The first capacitor, the second capacitor, and the third capacitor connected between the lines of the first wiring pattern and the third wiring pattern, and the first wiring pattern, the second wiring pattern, and the third wiring pattern. An inductor to be connected, wherein the second wiring pattern is provided between the first wiring pattern and the third wiring pattern, and the first wiring pattern and the third wiring pattern are respectively The first capacitor is connected to the bent portion of the first wiring pattern and the second wiring pattern, and the second capacitor is connected to the second wiring pattern. Capacitor is connected to the bent portion of the second wiring pattern and the third wiring pattern, the third capacitor is connected to the bent portion of the bent portion of the third wiring pattern and the first wiring pattern.

  In order to solve the above problems, an AC motor drive system according to the present invention includes a power converter that converts power input from a three-phase AC power source into three-phase AC power of variable voltage and variable frequency, and power An AC motor driven by the three-phase AC power output from the converter, and a three-phase noise filter connected to the input side or the output side of the power converter, the three-phase noise filter, 3 is a three-phase noise filter according to the present invention.

  According to the present invention, since the parasitic inductance is reduced by connecting a capacitor to the bent portion provided in the wiring pattern, the filter performance can be improved. Further, the improved filter performance improves the reliability of the AC motor drive system.

  Problems, configurations, and effects other than those described above will become apparent from the following description of embodiments.

1 shows an AC motor drive system according to an embodiment of the present invention. FIG. 2 is a layout diagram of a three-phase noise filter in the embodiment of FIG. 1. FIG. 3 is a circuit diagram of the three-phase noise filter of FIG. 2. It is a circuit diagram which shows the flow of the noise current in the three-phase noise filter of FIG. It is a circuit diagram of the three-phase noise filter which is another Example of this invention. FIG. 6 is a layout diagram of the three-phase noise filter of FIG. 5. It is a circuit diagram of the three-phase noise filter by a prior art. It is a circuit diagram which shows the flow of the noise electric current in the three-phase noise filter by a prior art.

  Embodiments of the present invention will be described below with reference to the drawings. In each figure, the same reference numerals indicate the same constituent elements or constituent elements having similar functions.

  FIG. 1 shows an AC motor drive system according to an embodiment of the present invention. The three-phase AC power supplied from the three-phase AC power source, in this embodiment the three-phase system power source 501, is received by the converter 502 via the three-phase noise filter 201. Converter 502 converts the received three-phase AC power into DC power. Inverter 503 converts the DC power input from converter 502 into variable voltage and variable frequency three-phase AC power. The three-phase AC power output from the inverter 503 is supplied to the three-phase AC motor 504 via the three-phase noise filter 201. The three-phase AC motor 504 is rotationally driven by the supplied three-phase AC power.

  Converter 502 includes a rectifier circuit made of a diode or made of a diode and a semiconductor switching element. The inverter 503 converts the DC power into three-phase AC power with a variable voltage and a variable frequency by controlling on / off of the semiconductor switching elements constituting the main circuit. Noise generated by the rectifying operation of the diode and the switching operation of the semiconductor switching element is absorbed by the three-phase noise filter 201 connected to the input side of the converter 502 and the output side of the inverter 503, respectively. Thereby, the influence of noise on the three-phase system power supply 501 and the three-phase AC motor 504 is alleviated. In addition, three-phase noise filter 201 connected to the input side of converter 502 prevents inflow of external noise from three-phase system power supply 501 to the power conversion device including converter 502 and inverter 503.

  As the semiconductor switching element, IGBT, MOSFET, GTO (Gate Turn-Off Thyristor) or the like can be applied. Further, as the three-phase AC motor, a permanent magnet type synchronous motor or an induction motor can be applied.

  The three-phase noise filter 201 may be connected to only one of the input side of the converter 502 and the output side of the inverter 503. Further, the characteristics of the three-phase noise filter 201 may be the same on the input side of the converter 502 and the output side of the inverter 503, or may be appropriately changed according to the characteristics of the converter 502 and the inverter 503.

  FIG. 2 is a layout diagram of the three-phase noise filter in the embodiment of FIG.

  As shown in FIG. 2, the three-phase noise filter 201 includes an inductor (common mode choke coil) 50 and a capacitor (X) on a substrate (for example, a printed circuit board) having a wiring pattern on an insulating plate made of resin or ceramic. Capacitors 11 to 13, 21 to 23, and Y capacitors 91 to 93). Here, capacitors (11-13, 21-23) connected to both sides of the inductor (common choke coil) 50 for reducing normal mode noise, and capacitors (91-93) for reducing common mode noise through ground. ) Are denoted as an X capacitor and a Y capacitor, respectively, in accordance with general names. Inductor 50 includes inductances 51 to 53, and inductances 51 to 53 are connected to the R phase, the S phase, and the T phase (or the U phase, the V phase, and the W phase), respectively.

  The three-phase noise filter 201 in this embodiment is an L-C type second-order low-pass filter configured with an inductor (common mode choke coil) 50 and Y capacitors 91 to 93 with respect to common mode noise. Also, for normal mode noise, a C-L-C type third order composed of X capacitors 11 to 13, a leakage inductance (not shown) of an inductor (common mode choke coil) 50, and X capacitors 21 to 23 is used. It becomes a low-pass filter.

  The three-phase noise filter 201 includes input terminals 1 to 3 and output terminals 4 to 6 corresponding to the number of phases of the three-phase system power supply, that is, the ground terminals 7 to which one ends of the Y capacitors 91 to 93 are connected. Is provided. In the three-phase noise filter 201 connected to the input side of the converter 502, the input terminals 1 to 3 are connected to the three-phase system power source 501, and the output terminals 4 to 6 are connected to the AC input of the converter 502. In the three-phase noise filter 201 connected to the output side of the inverter 503, the input terminals 1 to 3 are connected to the AC output of the inverter 503, and the output terminals 4 to 6 are connected to the three-phase AC motor 504.

  The normal mode noise propagates from the system three-phase power source 501 or the power converter (converter 502 and inverter 503). The propagated noise is cut off by the inductor (common mode choke coil) 50 and bypassed by the X capacitors 11 to 13 and 21 to 23, so that the input side from the output side or the output side of the three-phase noise filter 201. Suppresses noise passing to the input side.

  As for the common mode noise, a leakage current flows to the ground via a stray capacitance or the like existing in the insulator part according to the switching operation of the semiconductor switching element in the power converter (converter 502 and inverter 503). This leakage current is interrupted by the inductor (common mode choke coil) 50 and bypassed between the grounds by the Y capacitors 91 to 93, so that the outflow of noise toward the system three-phase power source 501 is suppressed.

  In the present embodiment, in the wiring patterns 111 to 113 for the three phases on the input terminal side provided on the substrate, the wiring pattern 111 of the first potential where the input terminal 1 is provided and the third potential where the input terminal 3 is provided. The wiring pattern 113 is bent so as to be close to the wiring pattern 112 of the second potential provided between the wiring patterns of the first potential and the third potential and extending linearly. The X capacitors 11 and 12 are respectively connected between the bent portion of the wiring pattern 111 of the first potential and the wiring pattern 112 of the second potential that are close to each other, and the wiring pattern 112 of the second potential and the third potential that are close to each other. Are connected between the bent portions of the wiring pattern 113. The X capacitor 13 has a second potential wiring pattern between the bent portion of the third potential wiring pattern 113 and the bent portion of the first potential wiring pattern 111 which are adjacent to each other with the wiring pattern 112 of the second potential in between. 112 and connected. Then, the X capacitors 11 to 13 are arranged in a triangular shape so that the distance between the terminals of the X capacitors 11 to 13 connected to the same wiring pattern is reduced and substantially equal on each wiring pattern. Is done.

  The first, second, and third potentials are the three-phase AC R, S, and T phase potentials, or the U, V, and W phase potentials, respectively.

  The wiring patterns 111 to 113 extend from the input terminals 1 to 3 toward the inductor (common mode choke coil) 50 and are connected to one end side terminals of the inductor (common mode choke coil) 50. Note that the wiring patterns 111 and 113 have a bent portion that is bent so as to approach the wiring pattern 112 extending linearly between the input terminals 1 to 3 and the inductor (common mode choke coil) 50 as described above.

  In the three-phase wiring patterns 121 to 123 on the output terminal side provided on the same substrate, the first potential wiring pattern 121 and the third potential wiring pattern 123 are connected to the first potential and the third potential wiring. It is bent so as to be close to the wiring pattern 122 of the second potential provided between the patterns and extending linearly. The X capacitors 21 and 22 are respectively connected between the bent portion of the first potential wiring pattern 121 and the second potential wiring pattern 122, and between the second potential wiring pattern 122 and the third potential, which are adjacent to each other. It is connected between the bent portions of the wiring pattern 123. The X capacitor 23 has a second potential wiring pattern between the bent portion of the third potential wiring pattern 123 and the bent portion of the first potential wiring pattern 121 which are adjacent to each other with the second potential wiring pattern 122 in between. 122 and connected. The X capacitors 21 to 23 are in a triangular shape so that the distance between the terminals of the X capacitors 21 to 23 connected to the same wiring pattern is reduced and substantially equal on each wiring pattern. Be placed.

  The wiring patterns 121 to 123 for the three phases on the output terminal side are connected to terminals on the other end side of the inductor (common mode choke coil) 50 and are directed from the inductor (common mode choke coil) 50 to the output terminals 4 to 6. And stretch. In the wiring patterns 121 to 123, portions that extend further beyond the output terminals 4 to 6 become end portions of the wiring patterns 121 to 123. A ground wiring pattern 131 having a ground terminal 7 is provided on the same substrate so as to be adjacent to the ends of the wiring patterns 121 to 123. Y capacitors 91 to 93 are connected between the ends of the wiring patterns 121 to 123 and the ground wiring pattern 131. Furthermore, the wiring patterns 121 and 123 have a bent portion that is bent so as to approach the linearly extending wiring pattern 122 between the output terminals 4 to 6 and the inductor (common mode choke coil) 50 as described above.

  In this embodiment, the wiring patterns 111 and 113 and the wiring patterns 121 and 123 are provided with bent portions for connecting X capacitors. For this reason, the wiring pattern does not include a protrusion or a branch for connecting the X capacitor, and has a uniform wiring width over the entire length. Furthermore, in the present embodiment, the widths of the wiring patterns 111 to 113 and 121 to 123 are all set to the same size. Therefore, the distribution of inductance and resistance is uniform in the length direction of the wiring pattern. Therefore, the parasitic inductance can be easily adjusted and reduced, and local heat generation due to the resistance component can be prevented.

  FIG. 3 is a circuit diagram of the three-phase noise filter of FIG. FIG. 4 is a circuit diagram showing the flow of noise current in the three-phase noise filter of FIG. In FIG. 3, normal mode noise is generated between the R phase (1) and the T phase (3) of the three-phase system power supply.

  3 and 7, according to the present embodiment, the parasitic inductance (151 to 154 in FIG. 7) is obtained in the connection portion between the X capacitors 11 to 13 and 21 to 23 due to the connection configuration of the wiring pattern and the X capacitor as described above. ) Is reduced.

  As shown in FIG. 4, the noise current is attenuated by the inductor (common mode choke coil) 50 and the X capacitors 11 to 13 and 21 to 23, but the noise current that has passed through the inductor (common mode choke coil) 50 is R-phase. And return to the three-phase power supply 501 via the X capacitors 21 to 23 connected to the T phase. Here, between the R phase (4) and the T phase (6) on the output terminal side, a parallel circuit of the X capacitor 23 and a series capacitor of the X capacitor 21 and the X capacitor 22 is connected. For this reason, the noise current is shunted to the X capacitor 23 side (shunt A) and to the series capacitor side (shunt B) of the X capacitor 21 and the X capacitor 22. At this time, since the terminals provided in the X capacitors 21 to 23 exist at positions where the terminals connected on the same wiring pattern are close to each other, the impedance between the terminals in the wiring patterns 121 to 123 is reduced, It is made uniform. Therefore, the amount of noise current flowing in the shunt A and shunt B does not depend on the impedance between the terminals of the X capacitors in the wiring patterns 121 to 123, but almost depends on the capacitance values of the X capacitors 21 to 23. For example, when the capacitance values of the X capacitors 21 to 23 are equal, the path on the shunt B side is a series capacitor of the X capacitor 21 and the X capacitor 22, so the substantial capacitance value on the shunt B side is the capacitance on the shunt A side. 1/2 of the value. As a result, the current ratio between the shunt A and the shunt B is 2: 1. Thus, since the current value corresponding to the X capacitor capacity can be obtained for both the shunts A and B, the noise removal performance of the three-phase noise filter can be improved.

  In FIG. 4, normal mode noise generated between the R phase (1) and the T phase (3) of the three-phase system power supply 501 is shown. However, due to the symmetry of normal mode noise, the R mode is actually R Normal mode noise is also generated between the phase (1) and the S phase (2) and between the S phase (2) and the T phase (3) with a phase shift of 120 degrees. Therefore, when viewed in one cycle, the average amount of current flowing through each X capacitor is equal. Further, when normal mode noise is generated on the power converter (converter 502 and inverter 503) side, the noise is removed by the X capacitors 11 to 13, but a noise current value corresponding to the X capacitor capacity is similarly obtained. Therefore, the noise removal performance of the three-phase noise filter can be improved.

  In addition, by applying the three-phase noise filter as described above to the AC motor drive system, system malfunction, failure, or performance deterioration due to noise can be prevented. Therefore, the reliability of the AC motor drive system is improved.

  FIG. 5 is a circuit diagram of a three-phase noise filter according to another embodiment of the present invention. FIG. 6 is a layout diagram of the three-phase noise filter of FIG. In addition, the three-phase noise filter of a present Example is applied to the alternating current motor drive system as shown in FIG.

  Hereinafter, differences from the embodiments shown in FIGS. 2 to 4 will be mainly described.

  The three-phase noise filter 201 in the embodiment of FIGS. 5 and 6 includes inductors (common mode choke coils) 50 and 60 and capacitors (X capacitors 11 to 13 or Y capacitors 91 to 93). The three-phase noise filter 201 in this embodiment is an L-C type secondary low-pass filter composed of inductors (common mode choke coils) 50 and 60 and Y capacitors 91 to 93 with respect to common mode noise. . In addition, for normal mode noise, the leakage inductance (not shown) of the inductor (common mode choke coil) 50, the X capacitors 11 to 13 and the leakage inductance (not shown) of the inductor (common mode choke coil) 60 are configured. L-C-L type third-order low-pass filter. The three-phase noise filter 201 includes input terminals 1 to 3 and output terminals 4 to 6 for the number of phases of the three-phase system power supply, that is, three phases, and a ground terminal 7 to which one end of a Y capacitor is connected. Inductor 60 includes inductances 61 to 63, and inductances 61 to 63 are connected to the R phase, the S phase, and the T phase (or the U phase, the V phase, and the W phase), respectively.

  The input terminals 1 to 3 are directly connected to terminals on one end side of the inductor (common mode choke coil) 50 through the wiring patterns 101 to 104 without using an X capacitor. Wiring patterns 111 to 113 similar to those in the embodiment of FIG. 2 are connected between a terminal on the other end side of the inductor (common mode choke coil) 50 and a terminal on one end side of the inductor (common mode choke coil) 60. The Further, the X capacitors 11 to 13 are connected between the lines of these wiring patterns as in the embodiment of FIG. Further, the terminal on the other end side of the inductor (common mode choke coil) 60 is directly connected to the output terminals 4 to 6 by the wiring patterns 104 to 106 without passing through the X capacitor. Similarly to the wiring patterns 121 to 123 in FIG. 2, Y capacitors 91 to 93 are connected between the ends of the wiring patterns 104 to 106 in FIG. 6 and the ground wiring pattern 131.

  The three-phase noise filter 201 in the embodiment of FIGS. 5 and 6 can increase the inductance for the common mode noise by connecting the inductors (common mode choke coils) 50 and 60 in series. 93 can be reduced to reduce the current flowing to the ground through the Y capacitor. For normal mode noise, since the impedance is viewed from the input side and output side of the three-phase noise filter 201 due to the L-CL type, the input side and output side of the three-phase noise filter 201 are high. This is effective when the circuit connected to the circuit has a low impedance.

  5 and 6 as described above can also improve the noise removal performance of the three-phase noise filter and improve the reliability of the AC motor drive system.

  In addition, this invention is not limited to the Example mentioned above, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  For example, in the three-phase noise filter of FIG. 2, the terminals on the other end side of the inductor (common mode choke coil) 50 are directly connected to the output terminals 4 to 123 by the wiring patterns 121 to 123 without providing the X capacitors 21 to 23. 6 may be connected. In this case, with respect to normal mode noise, a CL-type secondary low-pass filter constituted by the X capacitors 11 to 13 and the leakage inductance of the inductor (common mode choke coil) 50 is obtained. Further, in the three-phase noise filter of FIG. 6, the output terminals 4 to 6 may be directly connected to the wiring patterns 111 to 113 without providing the inductor (common mode choke coil) 60. In this case, with respect to normal mode noise, an L-C type second-order low-pass filter composed of the leakage inductance of the inductor (common mode choke coil) 50 and the X capacitors 11 to 13 is obtained.

  In the three-phase noise filter of FIGS. 2 and 5, only normal mode noise may be removed from normal mode noise and common mode noise without providing Y capacitors 91 to 93.

  In FIG. 1, the power conversion unit including the converter 502 and the inverter 503 is a so-called matrix converter circuit, and the three-phase AC power received from the three-phase system power supply is directly converted into the DC voltage without changing the variable voltage and You may convert into the variable frequency three-phase alternating current power.

1, 2, 3 Input terminal 4, 5, 6 Output terminal 7 Ground terminal 11, 12, 13 X capacitor 21, 22, 23 X capacitor 50 Inductor 51, 52, 53 Inductance 60 Inductor 61, 62, 63 Inductance 91, 92 , 93 Y capacitor 101, 102, 103, 104, 105, 106 Wiring pattern 111, 112, 113 Wiring pattern 121, 122, 123 Wiring pattern 131 Ground wiring pattern 201 Three-phase noise filter 501 Three-phase power supply 502 Converter 503 Inverter 504 AC motor

Claims (10)

A first wiring pattern, a second wiring pattern, and a third wiring pattern provided on the substrate;
A first capacitor, a second capacitor, and a third capacitor connected between each line of the first wiring pattern, the second wiring pattern, and the third wiring pattern;
An inductor connected to the first wiring pattern, the second wiring pattern, and the third wiring pattern;
In a three-phase noise filter comprising:
The second wiring pattern is provided between the first wiring pattern and the third wiring pattern,
Each of the first wiring pattern and the third wiring pattern has a bent portion that bends so as to approach the second wiring pattern;
The first capacitor is connected to the bent portion of the first wiring pattern and the second wiring pattern;
The second capacitor is connected to the bent portion of the second wiring pattern and the third wiring pattern,
The three-phase noise filter, wherein the third capacitor is connected to the bent portion of the third wiring pattern and the bent portion of the first wiring pattern. The three-phase noise filter according to claim 1,
The three-phase noise filter, wherein the third capacitor straddles the second wiring pattern. The three-phase noise filter according to claim 1,
Each of the first wiring pattern, the second wiring pattern, and the third wiring pattern has a uniform width. The three-phase noise filter according to claim 3,
Each of the first wiring pattern, the second wiring pattern, and the third wiring pattern has the same width, and the three-phase noise filter is characterized in that: The three-phase noise filter according to claim 1,
The terminal of the first capacitor and the terminal of the third capacitor connected to the first wiring pattern are close to each other;
The terminal of the first capacitor and the terminal of the second capacitor connected to the second wiring pattern are close to each other;
A terminal of the second capacitor and a terminal of the third capacitor connected to the third wiring pattern are close to each other;
The distance between terminals of the first capacitor and the third capacitor in the first wiring pattern, the distance between terminals of the first capacitor and the second capacitor in the second wiring pattern, and the third A three-phase noise filter characterized in that a distance between terminals of the second capacitor and the third capacitor in the wiring pattern is uniform. The three-phase noise filter according to claim 5,
The three-phase noise filter, wherein the first capacitor, the second capacitor, and the third capacitor are arranged in a triangular shape. The three-phase noise filter according to claim 1,
The three-phase noise filter further includes a fourth capacitor, a fifth capacitor, and a sixth capacitor that bypass common mode noise to the ground. The three-phase noise filter according to claim 1,
A three-phase noise filter, which operates as a CLC type third-order low-pass filter for normal mode noise. The three-phase noise filter according to claim 1,
A three-phase noise filter that operates as an L-C-L type third-order low-pass filter for normal mode noise. A power converter that converts power input from a three-phase AC power source into variable voltage and variable frequency three-phase AC power, and
AC motor driven by the three-phase AC power output by the power converter,
A three-phase noise filter connected to the input side or output side of the power converter;
In an AC motor drive system comprising:
The three-phase noise filter is
A first wiring pattern, a second wiring pattern, and a third wiring pattern provided on the substrate;
A first capacitor, a second capacitor, and a third capacitor connected between each line of the first wiring pattern, the second wiring pattern, and the third wiring pattern;
An inductor connected to the first wiring pattern, the second wiring pattern, and the third wiring pattern;
With
The second wiring pattern is provided between the first wiring pattern and the third wiring pattern,
Each of the first wiring pattern and the third wiring pattern has a bent portion that bends so as to approach the second wiring pattern;
The first capacitor is connected to the bent portion of the first wiring pattern and the second wiring pattern;
The second capacitor is connected to the bent portion of the second wiring pattern and the third wiring pattern,
The AC motor driving system, wherein the third capacitor is connected to the bent portion of the third wiring pattern and the bent portion of the first wiring pattern.

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