Noise filter and power conversion device

Abstract

To address a problem that reduction of parasitic inductance caused by a wire in a noise filter has not been taken into consideration and noise suppression in the noise filter has not been improved.SOLUTION: A noise filter includes: a first grounded capacitor that is connected between a positive electrode bus bar and a ground side, through the positive electrode bus bar and a positive electrode wire, and through the ground side and a ground wire; and a second grounded capacitor that is connected between a negative electrode bus bar and the ground side, through the negative electrode bus bar and a negative electrode wire, and through the ground side and the ground wire. The positive electrode wire and the negative electrode wire are arranged to be layered on the ground wire. The first grounded capacitor and the second grounded capacitor are arranged on one end side of the positive electrode wire, the negative electrode wire, and the ground wire which are arranged to be layered. A first connection part between the positive electrode bus bar and the positive electrode wire, a second connection part between the negative electrode bus bar and the negative electrode wire, and a third connection part between the ground side and the ground wire are arranged on the other end side of the wires.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a noise filter and a power conversion device. [Background technology]

[0002] Power conversion devices that convert DC power and AC power mutually by the switching operation of semiconductor elements are widely used in hybrid vehicles, electric vehicles, etc. In order to reduce the effects of noise generated by the switching operation of these semiconductor elements, a noise filter is provided on the power connector side of the power conversion device.

[0003] Patent document 1 discloses a noise filter in which a first earth capacitor and a second earth capacitor are arranged so that at least one of the directions from the third connection portion to the fourth connection portion of the first earth capacitor and the direction from the fifth connection portion to the sixth connection portion of the second earth capacitor forms a first adjustment angle greater than 0 degrees and less than 360 degrees with respect to the direction from the first connection portion to the second connection portion of the first line-to-line capacitor, when viewed from a direction perpendicular to the plane. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. WO2019 / 017003 Summary of the Invention [Problem to be solved by the invention]

[0005] The technology of Patent Document 1 does not take into consideration the reduction of parasitic inductance caused by wiring in the noise filter, and therefore cannot improve the noise suppression of the noise filter. [Means for solving the problem]

[0006] The noise filter according to the present invention comprises a first ground capacitor between a positive bus bar and a ground side, and connected via the positive bus bar and a positive wiring and also via the ground side and a ground wiring; and a second ground capacitor between a negative bus bar and the ground side, and connected via the negative bus bar and a negative wiring and also via the ground side and the ground wiring, wherein each of the positive wiring and the negative wiring are arranged in a stacked manner with respect to the ground wiring, the first ground capacitor and the second ground capacitor are arranged on one end side of each of the positive wiring, the negative wiring, and the ground wiring arranged in a stacked manner, and a first connection portion between the positive bus bar and the positive wiring, a second connection portion between the negative bus bar and the negative wiring, and a third connection portion between the ground side and the ground wiring are arranged on the other end side of each of the wiring. Effect of the Invention

[0007] According to the present invention, the parasitic inductance caused by the wiring of the noise filter can be reduced, and the noise suppression of the noise filter can be improved. [Brief description of the drawings]

[0008] [Figure 1] 1 is an overall configuration diagram of a power conversion device according to a first embodiment. [Diagram 2] 1 is a perspective view of a wiring substrate of a noise filter according to a first embodiment. FIG. [Diagram 3] 3A and 3B are top views of a wiring substrate of the noise filter according to the first embodiment. [Figure 4] 3 is an equivalent circuit of the noise filter in the first embodiment. [Diagram 5] FIG. 13 is a perspective view of a wiring board of a noise filter in a comparative example. [Figure 6] FIG. 13 is a top view of a wiring substrate of a noise filter in a comparative example. [Figure 7] 1 is a graph showing a coupling coefficient of mutual inductance in a noise filter. [Figure 8]1 is a graph showing input / output characteristics of a noise filter. [Figure 9] 3A and 3B are perspective views of a positive bus bar and a negative bus bar in the first embodiment. [Figure 10] 1 is a side view of a noise filter according to a first embodiment. [Figure 11] 1A and 1B are diagrams illustrating a wiring board in a first modified example. [Figure 12] 13A, 13B, and 13C are diagrams illustrating a wiring board in Modification 2. [Figure 13] 13A to 13E are diagrams illustrating a wiring board in Modification 3. [Figure 14] FIG. 11 is an overall configuration diagram of a power conversion device according to a second embodiment. [Figure 15] 13A and 13B are top views of a wiring board according to a second embodiment. [Figure 16] 13A and 13B are top views of a wiring board according to Modification 4. [Figure 17] FIG. 11 is an overall configuration diagram of a power conversion device according to a third embodiment. [Figure 18] FIG. 11 is an equivalent circuit diagram including a noise filter according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and appropriate omissions and simplifications have been made for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0010] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0011] [First embodiment] A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing the overall configuration of a power conversion device 10 according to this embodiment. The power conversion device 10 converts power between the battery 20 and the motor 30. For example, the power conversion device 10 converts DC power supplied from the battery 20 into AC power and supplies it to the motor 30. The power conversion device 10 also converts AC power supplied from the motor 30, which functions as a generator during regeneration, into DC power to charge the battery 20. It is sufficient for the power conversion device 10 to realize at least one of conversion from DC power to AC power and conversion from AC power to DC power.

[0012] The power conversion device 10 is covered with a metal housing, which serves as a reference potential for the power conversion device 10 and is connected to the ground side. A high-voltage DC cable is connected from a battery 20 to a connector 21 of the power conversion device 10. The power conversion device 10 is also connected to a connector 31 from a motor 30 via a high-voltage AC cable. The motor 30 is, although not particularly limited, configured by a three-phase electric motor.

[0013] The power conversion device 10 includes a noise filter 1, a smoothing capacitor 2, a power module 3 constituting an inverter circuit, a driver circuit board 4, and a control circuit board 5. DC power from a battery 20 is supplied to the power module 3 via a connector 21, a positive bus bar 6, and a negative bus bar 7.

[0014] The noise filter 1 is connected to a positive bus bar 6, a negative bus bar 7, and a ground bus bar 8. The ground bus bar 8 is connected to a housing of the power conversion device 10. The noise filter 1 will be described in detail later. The smoothing capacitor 2 suppresses pulsation of the DC voltage generated by the switching operation of the semiconductor elements in the power module 3 .

[0015] The power module 3 incorporates a semiconductor element and constitutes an inverter circuit. When the motor 30 is driven, the semiconductor element is switched in response to a gate signal from the driver circuit board 4, and the DC power supplied from the battery 20 is converted into AC power to drive the motor 30.

[0016] The driver circuit board 4 includes a driver circuit, converts the gate signal generated by the control circuit into a potential required for switching on and off the semiconductor element in the power module 3 , and outputs the converted signal to the power module 3 .

[0017] The control circuit board 5 includes a control circuit, and generates a gate signal based on a torque command value and the like given from a higher-level controller (not shown) of an electric vehicle or the like, to control the torque of the motor 30. At the connection portion between the positive bus bar 6 and the negative bus bar 7 and the noise filter 1, ferrite cores 91 and 92 are provided on both sides of the connection portion so as to surround the positive bus bar 6 and the negative bus bar 7.

[0018] When the power module 3 functions as an inverter, noise is generated due to the switching operation of the semiconductor elements. This noise is caused by voltage fluctuations relative to the ground and is generally called common mode noise. This common mode noise is transmitted via the positive bus bar 6 and the negative bus bar 7 due to the stray capacitance of each component of the power conversion device 10 and the like, and flows out into the high voltage DC cable connected between the connector 21 and the battery 20. The noise filter 1 is provided to reduce this common mode noise.

[0019] The noise filter 1 includes a positive Y capacitor 210 and a negative Y capacitor 220. Here, these Y capacitors 210 and 220 are also called earth capacitors. The positive Y capacitor 210 is connected between the positive bus bar 6 and the ground side via the positive bus bar 6 and the positive wiring 610, and also between the ground side and the ground wiring 810. The negative Y capacitor 220 is connected between the negative bus bar 7 and the ground side via the negative bus bar 7 and the negative wiring 710, and also between the ground side and the ground wiring 810. The positive wiring 610, the negative wiring 710, and the ground wiring 810 are, for example, wiring patterns formed on a multi-layer wiring board. The wiring connections of the noise filter 1 will be described in detail later.

[0020] 2 is a perspective view of wiring board 11 of noise filter 1, FIG. 3A is a top view of wiring board 110, and FIG.

[0021] The positive wiring 610, the negative wiring 710, and the ground wiring 810 of the noise filter 1 are formed in a wiring pattern of a wiring board 11 made of multiple layers. In the example shown in FIG. 2, FIG. 3(A), and FIG. 3(B), the positive wiring 610 and the negative wiring 710 are formed on the first wiring board 110, and the ground wiring 810 is formed on the second wiring board 120. The wiring board made of multiple layers may be a multilayer wiring board or may be a board in which wiring boards are stacked. These wiring boards 110 and 120 are fixed to the housing of the power conversion device 10 at multiple fixing points 12. The fixing points 12 are not electrically connected to the ground wiring 810.

[0022] As shown in FIG. 2, each of the positive wiring 610 and the negative wiring 710 is disposed in a stacked manner with respect to the ground wiring 810. 2, 3(A), and 3(B), the positive Y capacitor 210 and the negative Y capacitor 220 are disposed on one end side of the stacked positive wiring 610, the negative wiring 710, and the ground wiring 810. Specifically, at one end side of each wiring, one terminal of the positive Y capacitor 210 is connected to the positive wiring 610 at a connection part 211, and the other terminal of the positive Y capacitor 210 is connected to the ground wiring 810 of the second layer wiring board 120 at a connection part 212 via a through hole without contacting the positive wiring 610 of the first layer.

[0023] Similarly, at one end of each wiring, one terminal of negative Y capacitor 220 is connected to negative wiring 710 at connection part 221, and the other terminal of negative Y capacitor 220 is connected to ground wiring 810 of second layer wiring board 120 at connection part 222 via a through hole without contacting negative wiring 710 of the first layer. The connection means at connections 211, 212, 221, 222 is, for example, solder.

[0024] As shown in FIG. 3(A) and FIG. 3(B), the positive bus bar 6 and the positive wiring 610 are connected at a first connection portion 601. The negative bus bar 7 and the negative wiring 710 are connected at a second connection portion 701. The ground bus bar 8 to the ground side and the ground wiring 810 are connected at a third connection portion 801. Here, the first connection portion 601, the second connection portion 701, and the third connection portion 801 are disposed on the other end side of each of the wirings arranged in a stacked manner. Note that the connection means in the first connection portion 601, the second connection portion 701, and the third connection portion 801 is, for example, fastening by a bolt, but other connection means may be used.

[0025] That is, the positive wiring 610, the negative wiring 710, and the ground wiring 810 are arranged in a layered manner, with the positive Y capacitor 210 and the negative Y capacitor 220 arranged on one end of each wiring, and the first connection part 601, the second connection part 701, and the third connection part 801 arranged on the other end of each wiring. The reason for this arrangement will be explained below with reference to FIG. 4.

[0026] FIG. 4 shows an equivalent circuit of the noise filter 1. A parasitic inductance L10 of the positive wiring 610 exists between the positive Y capacitor 210 and the first connection part 601, and a parasitic inductance L11 of the ground wiring 810 exists between the positive Y capacitor 210 and the third connection part 801. In addition, a parasitic inductance L12 of the negative wiring 710 exists between the negative Y capacitor 220 and the second connection part 701, and a parasitic inductance L13 of the ground wiring 810 exists between the negative Y capacitor 220 and the third connection part 801.

[0027] Furthermore, a positive mutual inductance M1 exists between the parasitic inductance L10 and the parasitic inductance L11 with a high electromagnetic coupling coefficient due to the stacked arrangement of the positive wiring 610 and the ground wiring 810. A negative mutual inductance M2 exists between the parasitic inductance L12 and the parasitic inductance L13 with a high electromagnetic coupling coefficient due to the stacked arrangement of the negative wiring 710 and the ground wiring 810.

[0028] Noise NS flowing out from the power module 3 to the positive bus bar 6 and the negative bus bar 7 is bypassed from the first connection part 601 through the positive Y capacitor 210 to the third connection part 801, and from the second connection part 701 through the negative Y capacitor 220 to the third connection part 801. This suppresses noise flowing out from the power module 3 to the battery 20 side via the positive bus bar 6 and the negative bus bar 7. However, if each of the parasitic inductances L10, L11, L12, and L13 is large, the impedance increases depending on the frequency, and the bypass effect of the noise filter 1 on the noise NS is suppressed.

[0029] 2, 3(A), and 3(B), in this embodiment, the positive Y capacitor 210 and the negative Y capacitor 220 are disposed on one end of each wiring, and the first connection part 601, the second connection part 701, and the third connection part 801 are disposed on the other end of each wiring. Furthermore, the positive wiring 610 and the negative wiring 710 are disposed in a stacked manner with respect to the ground wiring 810.

[0030] As a result, the current flowing through the positive wiring 610 and the current flowing through the ground wiring 810 are in opposite directions. Therefore, the parasitic inductance L10 and the parasitic inductance L11 are offset by the mutual inductance M1 and reduced. That is, the parasitic inductance of the path from the positive bus bar 6 to the ground side is reduced. Similarly, the current flowing through the negative wiring 710 and the current flowing through the ground wiring 810 are in opposite directions. Therefore, the parasitic inductance L12 and the parasitic inductance L13 are offset by the mutual inductance M2 and reduced. That is, the parasitic inductance of the path from the negative bus bar 7 to the ground side is reduced.

[0031] Therefore, even if the parasitic inductances L10, L11, L12, and L13 are individually large, they can be offset and the bypass effect of the noise NS by the noise filter 1 is not suppressed. In other words, the parasitic inductance caused by the wiring of the noise filter 1 can be reduced, and the noise suppression of the noise filter 1 can be improved.

[0032] Fig. 5 is a perspective view of the wiring board 110 of the noise filter 1 in the comparative example, and Fig. 6 is a top view of the wiring board 110 of the noise filter 1 in the comparative example. The comparative example shown in Figs. 5 and 6 shows an example to which the present invention is not applied in order to deepen understanding of the present invention. The difference from this embodiment shown in Figs. 2, 3(A), and 3(B) is that the comparative example has wirings 610, 710, and wirings 810 arranged on one wiring board 110. The same reference numerals are used for the same parts as in Figs. 2, 3(A), and 3(B).

[0033] 5 and 6, in the comparative example, a positive wiring 610 and a negative wiring 710 are arranged on a wiring board 110, and further, a ground wiring 810 is arranged in the direction in which these wirings 610, 710 extend. A first connection portion 601 and a second connection portion 701 with the bus bars 6, 7 are arranged at one end of the positive wiring 610 and the negative wiring 710, and connection portions 211, 221 with the Y capacitors 210, 220 are arranged at the other end.

[0034] Furthermore, a ground wiring 810 is disposed from the connection parts 212, 222 of the Y capacitors 210, 220 in the direction in which the wirings 610, 710 extend, and a third connection part 801 is disposed at the end part of the ground wiring 810. The positive wiring 610 and the ground wiring 810, and the negative wiring 710 and the ground wiring 810 are not disposed in a stacked manner. Therefore, the currents flowing through the positive wiring 610 and the ground wiring 810, and the negative wiring 710 and the ground wiring 810 are in the same direction, so that the parasitic inductance is not cancelled out by the mutual inductance, and the filter effect is reduced.

[0035] Fig. 7 is a graph showing the coupling coefficients of mutual inductances M1 and M2 in the noise filter 1. The coupling coefficients in the present embodiment described with reference to Figs. 1 to 4 are shown on the left, and the coupling coefficients in the comparative examples described with reference to Figs. 5 and 6 are shown on the right.

[0036] The larger the absolute value of the electromagnetic coupling coefficient, the larger the mutual inductances M1 and M2 become. When the coupling coefficient is positive, the parasitic inductances L10, L11, L12, and L13 decrease due to the mutual inductances M1 and M2, and when the coupling coefficient is negative, they increase. In this embodiment, the coupling coefficients of the mutual inductances M1 and M2 are positive. The positive wiring 610 and the ground wiring 810, and the negative wiring 710 and the ground wiring 810 are arranged in layers, so the coupling coefficients are also large. According to this embodiment, since the coupling coefficients are also large, it can be seen that the reduction amounts of the parasitic inductances L10, L11, L12, and L13 are large.

[0037] On the other hand, in the comparative example, since the current directions are the same, the coupling coefficient of the mutual inductance M1 and the mutual inductance M2 is a negative value, as shown in Fig. 7. Therefore, the effect of reducing the parasitic inductance is not obtained. In addition, in the comparative example, the positive wiring 610 and the ground wiring 810, and the negative wiring 710 and the ground wiring 810 are not arranged in a layered manner, so the absolute value of the coupling coefficient is small. Even if it were possible to arrange the current directions in the opposite directions on one wiring board 110, the reduction effect would not be as great as that of the present embodiment, in which the current directions are arranged in a layered manner.

[0038] Furthermore, there is a demand for high voltage and miniaturization of the power conversion device 10, and accordingly, there is a demand for noise filters to be low profile and miniaturized. For this purpose, it is advantageous to arrange the wiring, capacitors, etc. on the wiring board 11. However, as in the example shown in the comparative example, depending on the layout of the wiring, capacitors, etc., parasitic inductance increases, and the effect of noise reduction by the noise filter cannot be sufficiently obtained.

[0039] Fig. 8 is a graph showing the input / output characteristics of the noise filter 1. The vertical axis represents the input / output characteristics (dB) and the horizontal axis represents the frequency (MHz). The input / output characteristics of the present embodiment described with reference to Figs. 1 to 4 are shown by solid lines, and the input / output characteristics of the comparative example described with reference to Figs. 5 and 6 are shown by dashed lines. At each frequency shown in Fig. 8, the lower the level of the input / output characteristics, the higher the noise reduction effect of the noise filter. Compared to the comparative example, the noise filter 1 of this embodiment has a higher parasitic inductance reduction effect as indicated by the arrow R in a frequency band higher than the resonance point RP, and it can be seen that the noise filter 1 of this embodiment has a higher noise reduction effect overall.

[0040] 2, 3(A), and 3(B), the positive Y capacitor 210 and the negative Y capacitor 220 are arranged side by side in a direction perpendicular to the direction connecting one end of each wiring 610, 710 and the other end of each wiring 610, 710. Specifically, the arrangement direction of the positive Y capacitor 210 (direction connecting the connection portion 211 and the connection portion 212) and the arrangement direction of the negative Y capacitor 220 (direction connecting the connection portion 221 and the connection portion 222) are arranged side by side in a direction perpendicular to the direction connecting the first connection portion 601, the second connection portion 701 of each wiring 610, 710 and each Y capacitor 210, 220.

[0041] By arranging each Y capacitor 210, 220 in this manner, the area in which the current flowing through the positive wiring 610 and the negative wiring 710 and the current flowing through the ground wiring 810 are in opposite directions is maximized, and the mutual inductances M1 and M2 are increased, making it possible to further improve the effect of reducing the parasitic inductance.

[0042] 9(A) and 9(B) are perspective views of the positive bus bar 6 and the negative bus bar 7 in this embodiment. Fig. 9(A) is a view from above, and Fig. 9(B) is a view from below, which is the substrate side. Both are in the vicinity of the first connection portion 601 and the second connection portion 701, and show a state in which the ferrite cores 91 and 92 are installed on the positive bus bar 6 and the negative bus bar 7.

[0043] 9(A) and 9(B), the first connection portion 601 of the positive bus bar 6 and the second connection portion 701 of the negative bus bar 7 have a convex shape. Although not shown, the third connection portion 801 of the ground bus bar 8 also has a convex shape. At least one of the first connection portion 601, the second connection portion 701, and the third connection portion 801 may be appropriately made convex depending on the installation form, etc. This convex portion of the convex shape is connected to the wiring pattern of each wire on the wiring board 11.

[0044] By forming each connection portion 601, 701, 801 of each bus bar 6, 7, 8 in such a convex shape, it becomes possible to contact each wiring 610, 710, 810 only around each connection portion 601, 701, 801. Furthermore, each bus bar 6, 7, 8 having a convex shape can be configured as a single part, which does not require welding compared to the case where each bus bar is a separate part, and is also effective in terms of cost reduction. Then, ferrite cores 91 and 92 are provided on both sides of the first connection portion 601 and the second connection portion 701 so as to surround the positive bus bar 6 and the negative bus bar 7 .

[0045] FIG. 10 is a side view of the noise filter 1 in this embodiment. This side view is a view of the noise filter 1 as seen from the side surface SV shown in FIG. 2, and shows a state in which the positive bus bar 6, the negative bus bar 7, and the ground bus bar 8 are connected to the wiring board 11, and ferrite cores 91 and 92 are installed.

[0046] 10, tall Y capacitors 210, 220 and bus bars 6, 7 and their connection parts 601, 701 are placed on the upper surface of wiring boards 110, 120, and ferrite cores 91, 92 are also placed to surround positive bus bar 6 and negative bus bar 7. By making connection parts 601, 701 of bus bars 6, 7 convex, a space for mounting ferrite cores 91, 92 is secured on the upper surface of wiring boards 110, 120. That is, ferrite cores 91, 92 are placed close to the same surface of wiring boards 110, 120 on which Y capacitors 210, 220 are placed.

[0047] In this way, the wiring board 11 can be miniaturized by arranging the wiring 610, 710, 810 and the capacitors, and the like, and the noise suppression of the noise filter can be improved by reducing the parasitic inductance caused by the wiring of the noise filter. The noise filter 1 may be equipped with either one of the ferrite cores 91, 92, or may not be equipped with them in some cases.

[0048] (Variation 1) 11(A) and 11(B) are diagrams showing wiring board 11 of noise filter 1 in Modification 1 of the present embodiment. Fig. 11(A) is a top view of wiring board 110 of a first layer, and Fig. 11(B) is a top view of wiring board 120 of a second layer.

[0049] 3(A) and 3(B) in that the width of each of the wirings 610, 710, and 810 is narrowed, and the Y capacitors 210 and 220 are arranged side by side along each of the wirings 610 and 710. The same parts as those in FIG. 3(A) and FIG. 3(B) are given the same reference numerals and their explanation will be simplified. 11(A) and 11(B), the positive bus bar 6 and the positive wiring 610 are connected at a first connection portion 601. The negative bus bar 7 and the negative wiring 710 are connected at a second connection portion 701.

[0050] Y capacitor 210 and Y capacitor 220 are arranged with their polarities facing opposite directions. Connection portion 211 of Y capacitor 210 is connected to positive wiring 610. Connection portion 212 of Y capacitor 210 is connected to ground wiring 810 of second-layer wiring board 120 via a through-hole without contacting positive wiring 610 of the first layer. Connection portion 221 of Y capacitor 220 is connected to negative wiring 710. Connection portion 222 of Y capacitor 220 is connected to ground wiring 810 of second-layer wiring board 120 via a through-hole without contacting negative wiring 710 of the first layer.

[0051] In other words, the Y capacitor 210 and the Y capacitor 220 are arranged side by side in the same direction as the direction connecting one end side of each of the wirings 610, 710 to the other end side of each of the wirings 610, 710. Furthermore, the Y capacitor 210 and the Y capacitor 220 are arranged with their polarities facing opposite directions.

[0052] In the first modification, the width of each of the wirings 610, 710, and 810 can be narrowed, thereby making it possible to miniaturize the wiring board 11 and further the noise filter 1. Also in the first modification, the currents flowing through the positive wiring 610 and the ground wiring 810, and the negative wiring 710 and the ground wiring 810 are in opposite directions, so that the parasitic inductance caused by the wiring is offset by the mutual inductance, thereby improving the noise suppression of the noise filter.

[0053] (Variation 2) 12(A), 12(B), and 12(C) are diagrams showing wiring board 11 of noise filter 1 in Modification 2 of this embodiment. Fig. 12(A) is a top view of wiring board 110 of the first layer, Fig. 12(B) is a top view of wiring board 120 of the second layer, and Fig. 12(C) is a top view of wiring board 130 of the third layer.

[0054] 3(A) and 3(B) is that ground wiring 810 is arranged on first-layer wiring board 110, positive wiring 610 and negative wiring 710 are arranged on second-layer wiring board 120, and ground wiring 810 is arranged on third-layer wiring board 130. The same reference numerals are used to designate the same parts as in Figures 3(A) and 3(B), and their description will be simplified.

[0055] As shown in Fig. 12(A) and Fig. 12(B), the positive wiring 610 and the negative wiring 710 arranged on the second-layer wiring board 120 are connected to the positive bus bar 6 and the negative bus bar 7 at the first connection portion 601 and the second connection portion 701, respectively, via the through holes of the first-layer wiring board 110. As shown in Fig. 12(A), Fig. 12(B), and Fig. 12(C), the ground wiring 810 arranged on the first-layer wiring board 110 and the third-layer wiring board 130 is connected to the ground bus bar 8 at the third connection portion 801, via the through holes of the second-layer wiring board 110. The connection portion 211 of the Y capacitor 210 is connected to the positive bus bar 6, and the connection portion 212 is connected to the ground wiring 810. The connection portion 221 of the Y capacitor 220 is connected to the positive bus bar 6, and the connection portion 222 is connected to the ground wiring 810.

[0056] Although the positive wiring 610 and the negative wiring 710 are disposed on the second-layer wiring board 120, the wiring board 11 may be made into a four-layer structure, with the ground wiring 810 disposed on the first-layer wiring board 110, the positive wiring 610 disposed on the second-layer wiring board 120, the negative wiring 710 disposed on the third-layer wiring board 120, and the ground wiring 810 disposed on the fourth-layer wiring board 130. Alternatively, the negative wiring 710 may be disposed on the second-layer wiring board 120, and the positive wiring 610 may be disposed on the third-layer wiring board 120.

[0057] In the second modification, the wiring boards 110 and 130, on which the ground wiring 810 is arranged, are arranged so as to sandwich the wiring board 120 on which the positive wiring 610 and the negative wiring 710 are arranged. Even in this second modification, the currents flowing through the positive wiring 610 and the ground wiring 810, and the negative wiring 710 and the ground wiring 810 are in the opposite directions, so that the parasitic inductance caused by the wiring is offset by the mutual inductance, and the noise suppression of the noise filter can be improved. Furthermore, by making the wiring board 11 three or more layers and appropriately arranging each of the wirings 610, 710, and 810 in each layer, it is possible to further improve the effect of reducing the parasitic inductance compared to the case of two layers.

[0058] (Variation 3) 13(A), 13(B), 13(C), 13(D), and 13(E) are diagrams showing wiring board 11 of noise filter 1 in Modification 3 of this embodiment. Fig. 13(A) is a top view of first-layer wiring board 110, Fig. 13(B) is a top view of second-layer wiring board 120, Fig. 13(C) is a top view of third-layer wiring board 130, Fig. 13(D) is a top view of fourth-layer wiring board 140, and Fig. 13(E) is a top view of fifth-layer wiring board 150.

[0059] 3(A) and 3(B) in that ground wiring 810 is arranged on first-layer wiring board 110, positive wiring 610 on second-layer wiring board 120, ground wiring 810 on third-layer wiring board 120, negative wiring 710 on fourth-layer wiring board 130, and ground wiring 810 on fifth-layer wiring board 110. The same reference numerals are used to designate the same parts as in Figures 3(A) and 3(B), and their description will be simplified.

[0060] As shown in Fig. 13(A) and Fig. 13(B), the positive wiring 610 arranged on the second-layer wiring board 120 is connected to the positive bus bar 6 at a first connection portion 601 via a through hole in the first-layer wiring board 110. As shown in Fig. 13(A), Fig. 13(B), Fig. 13(C), and Fig. 13(D), the negative wiring 710 arranged on the fourth-layer wiring board 120 is connected to the negative bus bar 7 at a second connection portion 701 via a through hole in the first-layer to third-layer wiring boards 110, 120, and 130. As shown in Fig. 13(A), Fig. 13(B), and Fig. 13(C), the ground wiring 810 arranged on the first-layer wiring board 110, the third-layer wiring board 130, and the fifth-layer wiring boards 110, 130, and 150 is connected to the ground bus bar 8 at a third connection portion 801 via a through hole in the second-layer and fourth-layer wiring boards 120 and 140. A connection portion 211 of the Y capacitor 210 is connected to the positive bus bar 6, and a connection portion 212 is connected to the ground wiring 810. A connection portion 221 of the Y capacitor 220 is connected to the positive bus bar 6, and a connection portion 222 is connected to the ground wiring 810.

[0061] In the third modification, the wiring board 120 on which the positive wiring 610 is arranged and the wiring board 140 on which the negative wiring 710 is arranged are sandwiched between the wiring boards 110, 130, and 150 on which the ground wiring 810 is arranged. In the third modification, the currents flowing through the positive wiring 610 and the ground wiring 810, and the negative wiring 710 and the ground wiring 810 are in the opposite directions, so that the parasitic inductance caused by the wiring is offset by the mutual inductance, and the noise suppression of the noise filter can be improved. Furthermore, by making the wiring board 11 three or more layers and appropriately arranging each of the wirings 610, 710, and 810 on each layer, it is possible to further improve the effect of reducing the parasitic inductance compared to the case of two layers. The negative wiring 710 may be arranged on the second layer wiring board 120, and the positive wiring 610 may be arranged on the fourth layer wiring board 130.

[0062] [Second embodiment] A second embodiment of the present invention will be described with reference to FIGS. FIG. 14 is an overall configuration diagram of a power conversion device 10 in this embodiment. 1 in that a pair of Y capacitors 230, 240 is added, and further an X capacitor 300 is added. The other configuration is the same as in FIG. 1, and the same parts are given the same reference numerals and their description will be simplified.

[0063] The noise filter 1 includes two pairs of Y capacitors, specifically, Y capacitors 210 and 220 and Y capacitors 230 and 240. In addition, the noise filter 1 includes one X capacitor 300. The X capacitor 300 is connected between the positive bus bar 6 and the negative bus bar 7, and is used to suppress normal mode noise. The X capacitor 300 is also called a line capacitor. The wiring connection of the noise filter 1 will be described in detail later.

[0064] FIG. 15A is a top view of a wiring substrate 110 of the noise filter 1 in this embodiment, and FIG. 15B is a top view of a wiring substrate 120 of the noise filter 1. As shown in FIG. The positive wiring 610, negative wiring 710, and ground wiring 810 of the noise filter 1 are formed in a wiring pattern of a wiring board 11 consisting of multiple layers. In the example shown in Fig. 15(A) and Fig. 15(B), the positive wiring 610 and the negative wiring 710 are formed on the first wiring board 110, and the ground wiring 810 is formed on the second wiring board 120. The positive bus bar 6 and the positive wiring 610 are connected at a first connection portion 601. The negative bus bar 7 and the negative wiring 710 are connected at a second connection portion 701. The ground bus bar 8 to the ground side and the ground wiring 810 are connected at a third connection portion 801.

[0065] The positive wiring 610, the negative wiring 710, and the ground wiring 810, that is, each wiring 610, 710, 810, are arranged in parallel in the same direction between the connection parts 211, 212, 221, 222, 231, 232, 241, 242 with the two pairs of Y capacitors 210, 220, 230, 243 and the connection parts 601, 701, 801 with each bus bar 6, 7, 8.

[0066] The Y capacitors 210, 220 and the Y capacitors 230, 240 are arranged side by side in the same direction as the direction connecting one end of each wiring 610, 710 to the other end of each wiring 610, 710. Furthermore, the Y capacitors 210, 220 and the Y capacitors 230, 240 are arranged with their polarities facing the same direction. In the example shown in Figures 15(A) and 15(B), two pairs of Y capacitors are shown, but three or more pairs may be provided.

[0067] The X capacitor 300 is disposed between one end of each of the wirings 610, 710 and the other end of each of the wirings 610, 710, and is connected to the positive wiring 610 at a connection portion 301 and to the negative wiring 710 at a connection portion 302. In the example of Fig. 15(A) and Fig. 15(B), the X capacitor 300 is disposed approximately midway between one end of each of the wirings 610, 710 and the other end of each of the wirings 610, 710. Furthermore, a plurality of X capacitors 300 may be provided between one end of each of the wirings 610, 710 and the other end of each of the wirings 610, 710.

[0068] (Variation 4) FIG. 16A is a top view of a wiring board 110 of a noise filter 1 in the fourth modified example of the present embodiment, and FIG. 16B is a top view of a wiring board 120 of the noise filter 1. As shown in FIG. 15(A) and 15(B) is that the polarities of the Y capacitors 230, 240 are arranged in a direction different from that of the Y capacitors 210, 220. The other configurations are the same as those in Figures 15(A) and 15(B), and the same parts are given the same reference numerals and their explanation will be simplified.

[0069] As shown in Figures 16(A) and 16(B), the Y capacitors 210, 220 and the Y capacitors 230, 240 are arranged with their polarities facing different directions. In this example, two pairs of Y capacitors are shown, but three or more pairs may be provided. In this case, each Y capacitor is also arranged with its polarity facing alternately. By arranging them in this way, the direction of the current from the positive wiring 610 and the negative wiring 710 to the ground wiring 810 alternates, so that the effect of reducing the parasitic inductance can be further improved.

[0070] [Third embodiment] A third embodiment of the present invention will be described with reference to FIGS. Fig. 17 is an overall configuration diagram of a power conversion device 10 in this embodiment. Fig. 18 is an equivalent circuit diagram including a noise filter 1 in this embodiment.

[0071] As shown in Fig. 17, in this embodiment, the ground side of the ground wiring of the noise filter 1 is connected to the ground wiring of the power module 3. The other configurations are similar to those in Fig. 1, and the same parts are given the same reference numerals and their description will be simplified.

[0072] 18 is an equivalent circuit diagram including some parasitic elements such as the housing of the power conversion device 10 and the power module 3 in addition to the noise filter 1. Reducing the parasitic inductances L10, L11, L12, and L13 of the noise filter 1 is effective for reducing noise, but in addition to the noise filter 1, there are also parasitic inductances L33 due to the grounding structure of the housing, etc., positive parasitic inductance L33 of the power module 3, and negative parasitic inductance L34 of the power module 3, etc. Reducing these parasitic inductances L33, L34, and L35 is effective in reducing common mode noise.

[0073] In the first embodiment, the parasitic inductance 33 is caused by the housing and the ground strap 820 to which the ground bus bar 8 is connected. On the other hand, in the present embodiment, the ground bus bar 8 is connected to the ground wiring of the power module 3, and therefore the ground wiring of the power module 3 is also included in the configuration of the parasitic inductance. In this case, by appropriately arranging the wiring structure on the power module 3 side, it is possible to reduce the parasitic inductances L33, L34, and L35 using the mutual inductances M31 and M32 between the positive electrode parasitic inductance L33 and the negative electrode parasitic inductance L34 of the power module 3, which is effective in reducing common mode noise.

[0074] In addition, since common mode noise flows through each wiring and generates radiated noise as an antenna, it is effective to reduce the radiation efficiency of each wiring as an antenna in addition to reducing the common mode noise in order to reduce the radiated noise. The larger the area of ​​the path loop of each wiring through which the common mode noise flows, the higher the radiation efficiency, so it is desirable to use wiring that minimizes the loop area. In this respect, compared to the first embodiment, the present embodiment is effective in reducing radiated noise because the common mode loop area can be reduced because the noise current passes through the ground wiring in the power module 3.

[0075] According to the embodiment described above, the following advantageous effects can be obtained. (1) The noise filter 1 includes a first ground capacitor (Y capacitor 210) between the positive bus bar 6 and the ground side, and connected via the positive bus bar 6 and the positive wiring 610 and also via the ground side and the ground wiring 810, and a second ground capacitor (Y capacitor 220) between the negative bus bar 7 and the ground side, and connected via the negative bus bar 7 and the negative wiring 710 and also via the ground side and the ground wiring 810. Each of the positive wiring 610 and the negative wiring 710 is connected to the ground wiring. The first ground capacitor (Y capacitor 210) and the second ground capacitor (Y capacitor 220) are arranged in a stacked manner with respect to the line 810, and are arranged on one end side of each of the stacked positive wiring 610, negative wiring 710, and ground wiring 810, and the first connection portion 601 between the positive bus bar 6 and the positive wiring 610, the second connection portion 701 between the negative bus bar 7 and the negative wiring 710, and the third connection portion 801 between the ground side and the ground wiring 810 are arranged on the other end side of each of the wirings 610, 710, 810. This reduces parasitic inductance caused by the wiring of the noise filter, and improves noise suppression of the noise filter.

[0076] The present invention is not limited to the above-described embodiment, and other forms that are conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention as long as they do not impair the characteristics of the present invention. In addition, the above-described embodiments may be combined with the above-described multiple modified examples. [Explanation of symbols]

[0077] 1 Noise filter, 2 Smoothing capacitor, 3 Power module, 4 Driver circuit board, 5 Control circuit board, 6 Positive bus bar, 7 Negative bus bar, 8 Ground bus bar, 10 Power converter, 11, 110, 120, 130, 140, 150 Wiring board, 12 Fixed point, 20 Battery, 21, 31 Connector, 30 Motor, 91, 9 2···Ferrite core, 210, 220···Y capacitor, 211, 212, 221, 222···Connection portion, 300···X capacitor, 601···First connection portion, 610···Positive wiring, 701···Second connection portion, 710···Negative wiring, 801···Third connection portion, 810···Ground wiring, L10, L11, L12, L13···Parasitic inductance, M1, M2···Mutual inductance.

Claims

1. a first ground capacitor between the positive bus bar and a ground side, the first ground capacitor being connected to the positive bus bar via a positive wiring and to the ground side via a ground wiring; a second ground capacitor between the negative bus bar and the ground side, the second ground capacitor being connected to the negative bus bar via a negative wiring and to the ground side via the ground wiring; The positive wiring and the negative wiring are each arranged in a stacked manner with respect to the ground wiring, the first earth capacitor and the second earth capacitor are disposed on one end side of each of the positive wiring, the negative wiring, and the ground wiring that are arranged in a stacked manner, A first connection portion between the positive bus bar and the positive wiring, a second connection portion between the negative bus bar and the negative wiring, and a third connection portion between the ground side and the ground wiring are noise filters arranged on the other end side of each of the wiring.

2. 2. The noise filter according to claim 1, The first earth capacitor and the second earth capacitor are noise filters arranged side by side in a direction perpendicular to a direction connecting the one end side of each of the wirings and the other end side of each of the wirings.

3. 2. The noise filter according to claim 1, The first earth capacitor and the second earth capacitor are noise filters that are arranged side by side in a direction connecting the one end side of each of the wirings and the other end side of each of the wirings.

4. 2. The noise filter according to claim 1, The noise filter is formed as a wiring pattern of a wiring board having multiple layers, in which the positive wiring, the negative wiring, and the ground wiring are arranged.

5. 5. The noise filter according to claim 4, The first ground capacitor and the second ground capacitor are noise filters disposed on the wiring board.

6. 6. The noise filter according to claim 5, At least one of the connection portions with the positive bus bar, the negative bus bar, and the ground side is convex, and the noise filter is connected to the wiring pattern on the wiring board at the convex portion of the convex shape.

7. 7. The noise filter according to claim 6, a ferrite core surrounding each of the positive bus bar connected to the first connection portion and the negative bus bar connected to the second connection portion, The ferrite core is a noise filter that is disposed close to the same surface of the wiring board on which the first earth capacitor and the second earth capacitor are disposed.

8. 5. The noise filter according to claim 4, The first earth capacitor and the second earth capacitor are provided in plurality, and are arranged side by side in the same direction as the direction connecting the one end side of each of the wirings to the other end side of each of the wirings.

9. 9. The noise filter according to claim 8, A noise filter in which the plurality of first earth capacitors and the plurality of second earth capacitors are arranged with the polarities of the capacitors alternating.

10. 5. The noise filter according to claim 4, A line capacitor is provided between the positive wiring and the negative wiring, The line capacitor is a noise filter disposed between the one end side of each of the wirings and the other end side of each of the wirings.

11. 5. The noise filter according to claim 4, The noise filter is a wiring board having multiple layers, in which a layer in which the positive wiring is arranged and a layer in which the negative wiring is arranged are sandwiched between a layer in which the ground wiring is arranged.

12. A noise filter according to any one of claims 1 to 11, a power module that configures an inverter circuit and converts DC power supplied from the positive bus bar and the negative bus bar via the noise filter into AC power.

13. 13. The power converter according to claim 12, The ground side of the ground wiring is connected to the ground wiring of the power module of the power conversion device.

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