Noise filter

Abstract

To provide a noise filter.SOLUTION: A noise filter comprises: first and second terminals, and comprises a wiring having first and second regions overlapping each other. The noise filter comprises a branch wiring having first and second wiring end parts. The first wiring end part is connected to the first region, and the second wiring end part is connected to a reference potential portion. The noise filter comprises a capacitor arranged at the branch wiring. The noise filter comprises a magnetic body surrounding the first and second regions, and one part of the branch wiring. The wiring comprises: a first conductive wire that connects from the first terminal to an intermediate part to which the first wiring end part is connected; and a second conductive wiring that connects from the intermediate part to the second terminal. The first region comprises a specific area surrounded by the magnetic body. The first wiring end part is positioned within the specific area.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The technology disclosed in this specification relates to a noise filter.

Background Art

[0002] In order to suppress electromagnetic noise that overlaps with a conductive wire, the development of noise filters has been promoted. Many of this type of noise filter include a capacitor for bypassing electromagnetic noise from the conductive wire to the ground. However, there is a parasitic inductance called equivalent series inductance (ESL) in the capacitor, and there is also parasitic inductance in the wiring to which the capacitor is connected. For this reason, it is known that such a noise filter cannot exhibit good filter performance for electromagnetic noise in the high-frequency band due to the influence of these parasitic inductances.

[0003] Patent Document 1 discloses a noise filter that reduces the parasitic inductances of a capacitor and a ground-side conductive wire by mutual inductance generated by magnetic coupling between an input-side conductive wire and an output-side conductive wire.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the technology of Patent Document 1, the balance between the parasitic inductances of the capacitor and the ground-side conductive wire and the mutual inductance generated between the input-side conductive wire and the output-side conductive wire may be disrupted. In this case, the filter performance deteriorates in the same way as when the parasitic inductance is large.

Means for Solving the Problem

[0006] One embodiment of the noise filter disclosed in this specification includes a winding having a first terminal and a second terminal, and a first region and a second region that overlap each other so that current flows in the same direction. The noise filter includes a branched wiring having a first wiring end and a second wiring end. The first wiring end is connected to the first region, and the second wiring end is connected to a reference potential site. The noise filter includes a capacitor disposed on the path of the branched wiring. The noise filter includes a magnetic body that surrounds at least a part of the first region and the second region and surrounds a part of the branched wiring. The winding includes a first conductive wire connecting the first terminal to an intermediate portion to which the first wiring end is connected, and a second conductive wire connecting the intermediate portion to the second terminal. The first region includes a specific region surrounded by the magnetic body. The first wiring end is located within the specific region.

[0007] In the noise filter of the above embodiment, the mutual inductance generated by the magnetic coupling between the first conductive wire and the second conductive wire can reduce the equivalent series inductance of the capacitor and the parasitic inductance of the branched wiring. Then, by making the distance from one end of the specific region to the intermediate portion different from the distance from the intermediate portion to the other end of the specific region, the mutual inductance can be adjusted. In other words, the mutual inductance can be made small when one end of the specific region is the intermediate portion, and can be made large when the other end of the specific region is the intermediate portion. Therefore, by changing the position of the intermediate portion within the range from one end to the other end of the specific region, the mutual inductance can be changed. Thereby, it becomes possible to appropriately adjust the balance between the equivalent series inductance and the parasitic inductance, and the mutual inductance. It becomes possible to suppress the deterioration of the filter performance.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

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Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Mode for Carrying Out the Invention

[0009] (Principle of Noise Reduction Effect) Before explaining the noise filter disclosed in this specification, refer to FIG. 1 and explain the noise transfer characteristics of the T-shaped noise filter 1 with an LCL configuration. The noise filter 1 includes a pair of inductors L1 and L2 connected in series to a power conductive line, and a capacitor C connected between the power conductive line and a reference conductive line. The inductance of inductor L1 is L1, and the inductance of inductor L2 is L2. Note that these inductors L1 and L2 may be parasitic inductors of the power conductive line. One end of the capacitor C is connected to a branch between the pair of inductors L1 and L2, and the other end is connected to the reference conductive line. The inductance L3 of inductor L3 is the sum of the ESL of capacitor C and the parasitic inductance of the wiring to which capacitor C is connected. Z1 is the internal impedance of the noise source, and Z2 is the impedance of the load circuit. In this noise filter 1, inductors L1 and L2 are magnetically coupled. Assuming that the currents I1 and I2 flowing through inductors L1 and L2 respectively flow in the directions shown in the figure, and a positive mutual inductance M is generated between these inductors L1 and L2. Let the noise voltage be V noise Then, the noise voltage V L applied to the load circuit is represented by the following equation.

[0010]

Equation

[0011] As shown in the above mathematical formula 1, the noise voltage V LTo reduce it, it is important to reduce the "Z L3 +Z C " of the molecule. Since the amplitude of the noise voltage V L is represented by the absolute value, taking the absolute value of the above Equation 1 and setting its numerator to V num , it can be expressed by the following equation.

Equation

[0012] According to the above Equation 2, it can be seen that the filter performance is maximized when the mutual inductance M is set so that {ω(L3 - M)-1 / ωC} becomes 0. However, such conditions are realized only at a certain arbitrary frequency. Therefore, a noise filter circuit for reducing noise over a wide range of frequencies is not set under such conditions.

[0013] Here, the mutual inductance M generated between the inductor L1 and the inductor L2 can be expressed by the following equation using the coupling coefficient k.

Equation

[0014] The coupling coefficient k is a value indicating the degree of magnetic coupling, and in the structure disclosed in this specification, it takes a value of 0 ≦ k ≦ 1. As shown in the above Equation 2 and the above Equation 3, by adjusting the values of k, L1, and L2 so that the inductance L3 and the mutual inductance M match, only the product of the impedance of the capacitor C and the impedance of the load circuit remains in the numerator of the above Equation 1. Since the angular frequency ω increases as the frequency increases, if the inductance L3 and the mutual inductance M are made to match, the filter performance for high-frequency band electromagnetic noise is improved.

[0015] That is, as shown in FIG. 2, by magnetically coupling inductor L1 and inductor L2, if the inductance L3 is reduced by the mutual inductance M generated between inductor L1 and inductor L2, the filter performance against electromagnetic noise in the high-frequency band can be improved. The technology disclosed in this specification utilizes this phenomenon to improve the filter performance against electromagnetic noise in the high-frequency band.

Embodiment

[0016] (Structure of Noise Filter 1) FIG. 3 shows a perspective view of the noise filter 1 according to Embodiment 1. FIG. 4 shows an exploded perspective view of the noise filter 1. The noise filter 1 is an LCL-configured T-type noise filter composed of the inductance of the first conductive wire CW1, the capacitors 31 and 32 inserted between the connection paths of the branch wiring 60 and the ground plate 15, and the inductance of the second conductive wire CW2. The noise filter 1 mainly includes a substrate 10, a winding 2, a ground plate 15, capacitors 31 and 32, a branch wiring 60, and a magnetic core 70.

[0017] The winding 2 includes an upper bus bar 3 and a lower bus bar 4. The upper bus bar 3 is disposed on the surface S2 of the substrate 10. The lower bus bar 4 is disposed on the back surface S1 of the substrate 10. The upper bus bar 3 and the lower bus bar 4 are connected by a via wiring 41 passing through the substrate 10. Thereby, the output terminal E1 and the input terminal E2 are electrically connected.

[0018] The upper bus bar 3 and the lower bus bar 4 have a straight flat plate structure and face each other via the substrate 10. As a result, the two bus bars are arranged in parallel in an insulated state from each other and are arranged linearly and closely. Note that the distance between the two bus bars can be freely set. This is because the magnetic fluxes generated by the upper bus bar 3 and the lower bus bar 4 respectively are confined in the magnetic core 70. When the substrate 10 is viewed from directly above (+z direction), each of the lower bus bar 4 and the upper bus bar 3 has a first region A1 and a second region A2 that overlap each other (see FIG. 4).

[0019] The winding 2 includes a first conductive wire CW1 and a second conductive wire CW2. The first conductive wire CW1 is a part that connects the output terminal E1 and the intermediate part MP. The second conductive wire CW2 is a part that connects the intermediate part MP and the input terminal E2. The output terminal E1 is a part connected to an arbitrary load. The input terminal E2 is a part connected to a power converter (not shown) such as a converter or an inverter that serves as a noise source. The intermediate part MP is a part to which the first wiring end 61E1 of the first branch wiring 61 is connected.

[0020] The branch wiring 60 includes a first branch wiring 61 and a second branch wiring 62. The first branch wiring 61 has a flat plate structure. The second branch wiring 62 is disposed on the surface S2 of the substrate 10. The second branch wiring 62 may be a printed wiring. The first branch wiring 61 includes a first wiring end 61E1 and a connection end 61Ec. The second branch wiring 62 includes a second wiring end 62E2 and a connection end 62Ec. The first wiring end 61E1 is connected to the intermediate part MP of the lower bus bar 4 by the connection terminal 42. The connection end 61Ec is connected to the via wiring 44 by the connection terminal 43. The via wiring 44 penetrates the substrate 10 and is connected to the connection end 62Ec of the second branch wiring 62.

[0021] Note that the connection position to the lower bus bar 4 of the intermediate part MP is configured to be freely changeable in the longitudinal direction (i.e., the x-direction) of the first region A1. For example, the connection terminal 42 may be provided with a fastening member such as a bolt and may be fixed at an arbitrary position of the lower bus bar 4.

[0022] The -y direction end of the second branch wiring 62 and the second wiring end 62E2 are connected via the capacitor 31. The second wiring end 62E2 and the ground plate 15 are connected via the capacitor 32. That is, the capacitor 31 and 32 connected in series with each other connect the second branch wiring 62 and the ground plate 15. By adopting a structure in which a plurality of capacitors are connected in series, redundancy can be provided so that the second branch wiring 62 does not short-circuit with the ground plate 15 even when any one of the capacitors has a short-circuit failure. In the examples of FIGS. 3 and 4, the capacitors 31 and 32 are 4-parallel chip capacitors (multilayer ceramic capacitors).

[0023] As shown in FIG. 4, the substrate 10 includes two through holes H1 and H2 arranged side by side in the y-direction. The through holes H1 and H2 are arranged at positions facing each other with the first region A1 and the second region A2 interposed therebetween. The magnetic core 70 includes a substantially U-shaped magnetic body portion 71 and a substantially I-shaped magnetic body portion 72. The magnetic body portion 71 includes columnar portions P1 and P2 and a connecting portion J1. The connecting portion J1 is a portion that connects the +z direction side end of the columnar portion P1 and the +z direction side end of the columnar portion P2. The columnar portion P1 is provided with an end face P1E at the -z direction side end. The columnar portion P2 is provided with an end face P2E at the -z direction side end. A groove portion 70t extending in the x-direction is formed between the columnar portions P1 and P2.

[0024] The columnar portions P1 and P2 have a shape that can be fitted into the through holes H1 and H2. The magnetic body portion 72 is arranged so as to face the end face P1E of the columnar portion P1 and the end face P2E of the columnar portion P2. By combining the magnetic body portions 71 and 72 through the through holes H1 and H2, a magnetic core 70 that is disposed through the substrate 10 can be formed. Further, by closing the groove portion 70t with the magnetic body portion 72, an annular structure can be formed. At least a part of the first region A1 and the second region A2, and the intermediate portion MP are disposed inside the groove portion 70t. That is, the magnetic core 70 is disposed so as to surround at least a part of the first region A1 and the second region A2 and at least a part of the first branch wiring 61. Note that an insulating layer for preventing contact may be disposed between the outer circumferences of the first conductive wire CW1 and the second conductive wire CW2 and the inner circumference of the magnetic core 70.

[0025] The first region A1 includes a specific region SA which is a region surrounded by the magnetic core 70. The first wiring end portion 61E1 is located within the specific region SA. Here, one end of the specific region SA in the -x direction is defined as the first region end SAe1. Also, the other end of the specific region SA in the +x direction is defined as the second region end SAe2. The distance from the first region end SAe1 to the intermediate portion MP is defined as D1. The distance from the intermediate portion MP to the second region end SAe2 is defined as D2. The magnitude relationship between the distances D1 and D2 can be set as appropriate. The distances D1 and D2 may be different or equal. In this embodiment, the distances D1 and D2 are different.

[0026] Fig. 5 shows an enlarged perspective view of the magnetic core 70. In Fig. 5, for clarity, the description of the substrate 10 is omitted. As shown in Fig. 5, a gap G1 is formed at the joint between the magnetic parts 71 and 72. The connecting conductive wire 61 extends in the y direction orthogonal to the extending direction (x direction) of the groove portion 70t. And the connecting conductive wire 61 extends from the intermediate portion MP, passes through the gap G1, and extends toward the outside of the magnetic core 70. Among the first branch wirings 61, the portion disposed in the gap G1 is surrounded by the magnetic core 70. This portion surrounded by the magnetic core 70 is defined as the specific wiring portion 61s. The specific wiring portion 61s extends in the y direction. Also, the specific wiring portion 61s passes through the region where the end face P1E of the columnar portion P1 and the magnetic part 72 face each other in the z direction.

[0027] An insulating spacer 73 is disposed in the gap G1. Specifically, the spacer 73 is sandwiched between the magnetic parts 71 and 72. The gap G1 can be adjusted according to the thickness of the spacer 73. Thereby, the mutual inductance between the first conductive wire CW1 and the second conductive wire CW2 can be adjusted. The material of the spacer 73 can be various, for example, it can be a polymer film.

[0028] When viewed from the direction (z direction) perpendicular to the end face P1E, a cut SL is formed in the spacer 73 in the region corresponding to the first branch wiring 61. That is, the spacer 73 is disposed in the region within the end face P1E where the specific wiring portion 61s does not exist. When changing the position of the intermediate portion MP, the position of the cut SL of the spacer 73 may be changed so as to correspond to the position of the first branch wiring 61 after the change.

[0029] The thickness of the spacer 73 may be thicker than the thickness of the specific wiring portion 61s. Thereby, it becomes possible to form a space through which the first branch wiring 61 passes.

[0030] (Effect obtained by adjusting the position of the intermediate portion MP) As described above, the position where the first wiring end portion 61E1 of the first branch wiring 61 is connected to the lower bus bar 4 (i.e., the position of the intermediate portion MP) is changeable. Also, the position of the intermediate portion MP is changeable within the first region A1. Thereby, the mutual inductance M between the first conductive wire CW1 on the output side and the second conductive wire CW2 on the input side can be variably adjusted. The reasons are explained below.

[0031] Fig. 6 shows an equivalent circuit of the inductor LL. Let the total inductance of the inductor LL be L and the total number of turns be n. In the first conductive wire CW1 on the output side, let the self-inductance be L1 and the number of turns be n1. In the second conductive wire CW2 on the input side, let the self-inductance be L2 and the number of turns be n2. Let the mutual inductance between the first conductive wire CW1 and the second conductive wire CW2 be M (>0). The inductance L is expressed by the following equation. L = L1 + L2 + 2M Also, the total number of turns n is expressed by the following equation. n = n1 + n2 Since the total number of turns n does not change even when the position of the intermediate portion MP changes, the inductance L does not change.

[0032] The self-inductance L1 is proportional to the square of the number of turns n1. Thus, it is expressed by the following equation. L1 = L0·n1 2 Similarly, the self-inductance L2 is proportional to the square of the number of turns n2. Thus, it is expressed by the following equation. L2 = L0·n2 2 Here, L0 is the proportionality constant of the inductance.

[0033] When the coupling between the first conductive wire CW1 and the second conductive wire CW2 is strong, the coupling coefficient k can be approximated to be approximately equal to 1. In this case, the mutual inductance M is expressed by the following equation.

Equation

[0034] Here, the proportionality constant of inductance \(L0 = 1\) and the total number of turns \(n = 1\) are both normalized. The change in mutual inductance \(M\) with respect to the number of turns \(n2\) of the second conductive wire \(CW2\) in the case of normalization is shown in FIG. 7. As can be seen from FIG. 7, as the number of turns \(n2\) increases (as the number of turns \(n2\) approaches 1), the self - inductance \(L2\) increases and the self - inductance \(L1\) decreases. And when the number of turns \(n2\) is 0.5, the self - inductances \(L1\) and \(L2\) are equal, and the mutual inductance \(M\) becomes the maximum value of 0.25.

[0035] And changing the connection position of the intermediate part \(MP\) to the lower bus bar 4 is equivalent to changing the number of turns \(n2\) of the first conductive wire \(CW1\) within the variable range \(VR\) in FIG. 7. The number of turns \(n2\) becomes 0.5 when the intermediate part \(MP\) is located at the mid - point \(PP\) (see FIG. 4) between the output terminal \(E1\) and the input terminal \(E2\). In this embodiment, the intermediate part \(MP\) is located closer to the output terminal \(E1\) than the mid - point \(PP\). Therefore, the variable range \(VR\) is larger than 0.5. In this embodiment, the variable range \(VR\) is approximately in the range from 0.7 to 0.95. Moving the intermediate part \(MP\) closer to the output terminal \(E1\) (i.e., moving it in the - x direction) corresponds to making the second conductive wire \(CW2\) longer and the first conductive wire \(CW1\) shorter, so it corresponds to approaching the number of turns \(n2\) to 1. That is, the closer the intermediate part \(MP\) is to the output terminal \(E1\), the larger the self - inductance \(L2\) can be made and the smaller the self - inductance \(L1\) can be made. Therefore, as can be seen from FIG. 7, it can be seen that the closer the intermediate part \(MP\) is to the output terminal \(E1\), the smaller the mutual inductance \(M\) can be.

[0036] (Effect) Describe the problem. In the technology of this specification, the mutual inductance M generated between the first conductive wire CW1 on the output side and the second conductive wire CW2 on the input side can reduce the sum of the equivalent series inductance of the capacitors 31 and 32 and the parasitic inductance of the branch wiring 60. As a result, it becomes possible to exhibit high filter performance against electromagnetic noise in the high-frequency band. However, the balance between the parasitic inductances of the capacitors 31, 32 and the branch wiring 60 and the mutual inductance M may be disrupted. For example, in order to improve the performance of the noise filter 1, the mutual inductance M may become larger than the parasitic inductance by increasing the inductance between the ends (such as by increasing the magnetic permeability of the magnetic core 70). Another example is when the parasitic inductance changes due to a change in the arrangement of the capacitors. Thus, even when the balance between the parasitic inductance and the mutual inductance M is greatly disrupted, the filter performance deteriorates. Therefore, in the technology of this embodiment, the position of the intermediate portion MP, which is the portion where the first branch wiring 61 is drawn out, is configured to be changeable within a specific region SA of the lower bus bar 4. And by appropriately adjusting the distance D1 from the first region end SAe1 to the intermediate portion MP and the distance D2 from the intermediate portion MP to the second region end SAe2, the mutual inductance M can be adjusted. As a result, since the balance between the equivalent series inductance and the parasitic inductance and the mutual inductance can be appropriately adjusted, it becomes possible to suppress the deterioration of the filter performance.

[0037] In the technology of this embodiment, by arranging the first branch wiring 61 in the gap G1, a structure in which the first branch wiring 61 is surrounded by the magnetic core 70 is realized. That is, the gap G1 that inevitably exists because the magnetic core 70 has a split structure can be diverted as a path for the first branch wiring 61 to pass through. It becomes possible to form the specific wiring portion 61s without performing special processing or the like on the magnetic core 70. Also, in the technology of this embodiment, the first branch wiring 61 is arranged in the cut SL formed in the spacer 73. That is, the spacer 73 that is inevitably arranged because the gap G1 exists can be diverted as a guide for fixing the first branch wiring 61 at a predetermined position. It becomes possible to fix the position of the specific wiring portion 61s without adding a special fixing member.

Embodiment

[0038] FIG. 8 shows an exploded perspective view of the noise filter 201 according to Embodiment 2. Embodiment 2 mainly differs from Embodiment 1 in that a guide groove is formed in the magnetic core. Hereinafter, the differences from Embodiment 1 will be described. Also, the same reference numerals are given to the common parts between the noise filter 201 of Embodiment 2 and the noise filter 1 of Embodiment 1 to omit the description. Note that the parts unique to Embodiment 2 are distinguished by using reference numerals in the 200s.

[0039] The winding 202 with a flat structure includes an upper winding and a lower winding that overlap in the z direction. Connection portions 202c1 and 202c2 protruding in the -y direction are formed at both ends of the lower winding. The substrate 210 also includes three through holes H1, H2a, and H2b. A branch wiring 260 extending in the y direction is arranged between the through holes H2a and H2b. A parallel wiring 280 extending in the x direction is arranged between the through hole H1 and the through holes H2a and H2b. Connection portions 280c1 and 280c2 are arranged at both ends of the parallel wiring 280. Each of the connection portions 280c1 and 280c2 is configured to be electrically connectable to the connection portions 202c1 and 202c2. Thereby, the lower winding of the winding 202 and the parallel wiring 280 can be connected in parallel. Each of the winding 202 and the parallel wiring 280 includes a first region A1 and a second region A2 that overlap each other.

[0040] The first region A1 includes a specific region SA which is a region surrounded by the magnetic core 70. Let the distance from the first region end SAe1 to the middle part MP be D1. Let the distance from the middle part MP to the second region end SAe2 be D2. The distance D1 is smaller than the distance D2.

[0041] The branch wiring 260 is arranged on the surface S2 of the substrate 210. The branch wiring 260 includes a first wiring end 260E1 and a second wiring end 260E2. The first wiring end 260E1 is connected to the middle part MP of the parallel wiring 280. The second wiring end 260E2 and the ground plate 15 are connected via a capacitor 32. Note that the parallel wiring 280 and the branch wiring 260 may be wirings printed integrally on the surface S2.

[0042] On the end face P1E of the magnetic body portion 271, a guide groove GT extending in the y direction is formed. The +y direction end of the guide groove GT communicates with the groove portion 270t, and the -y direction end reaches the side wall of the columnar portion P1. By combining the magnetic body portions 271 and 272 through the through holes H1, H2a, and H2b, a part of the branch wiring 260 can be accommodated inside the guide groove GT. Among the branch wiring 260, the portion disposed inside the guide groove GT is surrounded by the magnetic core 270. The portion surrounded by this magnetic core 270 is defined as the specific wiring portion 260s.

[0043] Also in the noise filter 201 of the second embodiment, the same effects as those of the first embodiment can be obtained. That is, by appropriately adjusting the distance D1 from the first region end SAe1 to the intermediate portion MP and the distance D2 from the intermediate portion MP to the second region end SAe2, it becomes possible to adjust the mutual inductance M.

[0044] Note that the method for adjusting the distances D1 and D2 may be various. The intermediate portion MP and the branch wiring 260 may be moved to arbitrary positions in the x direction, and the guide groove GT may be formed in accordance with the position of the branch wiring 260 after the movement. For example, when the branch wiring 260 is formed of printed wiring, the mask of the substrate 210 may be changed.

[0045] (Modification of the second embodiment) The arrangement position and shape of the guide groove GT may vary. As shown in the example of FIG. 9, two guide grooves GT1 and GT2 may be formed on each of the end faces P1E and P2E. In the example of FIG. 9, the guide grooves GT1 and GT2 are arranged symmetrically with respect to the central plane CP passing through the groove portion 270t. Thus, by rotating the magnetic body portion 271 180 degrees around the central axis CA extending in the z direction, the x-direction position of the guide groove can be changed. Therefore, one magnetic body portion 271 can be used to handle two types of substrates 210 with different x-direction positions in the intermediate portion MP. Also, as shown in the example of FIG. 10, the guide grooves GT1 and GT2 may be arranged rotationally symmetrically with respect to the central axis CA. This eliminates the need to consider the orientation of the magnetic body portion 271, thus making it possible to improve the assemblability.

[0046] Although the case where the branch wiring 260 is a printed wiring on the substrate 210 has been described, it is not limited to this form. For example, the branch wiring 260 may have a flat plate structure such as a bus bar. This eliminates the need for a substrate portion to support the branch wiring 260, so the through holes H2a and H2b (FIG. 8) can be integrated like the through hole H2 (FIG. 4) in the first embodiment. Therefore, it is possible to change the branch wiring 260 to an arbitrary position in the x direction without changing the substrate 210.

Embodiment

[0047] In the third embodiment, the first aspect of the magnetic body portion 271 will be described. FIG. 11 shows a bottom view of the magnetic body portion 271. FIG. 11 is a view seen from the direction (-z direction) perpendicular to the end face P1E. The end faces P1E and P2E are arranged at the lower ends of the columnar portions P1 and P2, respectively. A guide groove GT extending in the y direction is formed in a part of the end face P1E. A first branch wiring 61 is arranged inside the guide groove GT. In other words, the guide groove GT is an area overlapping with the specific wiring portion 61s.

[0048] Let the y-direction widths of the columnar portions P1 and P2 be W1 and W2, respectively. The width W1 is larger than the width W2. Also, let the area of the region on the end face P1E where the guide groove GT is not formed (i.e., the region that does not overlap with the specific wiring portion 61s) be the area AR1. Further, let the area of the end face P2E be the area AR2. The widths W1 and W2 are defined such that the areas AR1 and AR2 are substantially the same.

[0049] (Effect) The maximum magnetic flux density is determined by the smaller cross-sectional area of the magnetic path on the end faces P1E and P2E. In this embodiment, on the end faces P1E and P2E, the cross-sectional area of the magnetic path can be made the same. Thus, while minimizing the increase in the size of the magnetic core 270, it is possible to prevent the magnetic flux density of a specific portion from increasing unevenly. As a result, it is possible to prevent a situation where the magnetic flux density exceeds the saturation magnetic flux density and the inductance decreases. It becomes possible to reduce the size of the magnetic core for obtaining the required inductance value.

[0050] (Modification of Example 3) The technology of Example 3 is applicable to magnetic cores of various structures. For example, it may be applied to the magnetic body portion 71 (FIG. 5) in Example 1. In this case, the area of the region on the end face P1E that does not overlap with the specific wiring portion 61s may be defined as the area AR1.

Example

[0051] In Example 4, a second aspect of the magnetic body portion 271 will be described. FIGS. 12 and 13 show a bottom view of the magnetic body portion 271. The guide groove GT11 in FIG. 12 includes a portion extending in the -y direction from the intermediate portion MP, a portion that bends at a right angle midway, and a portion extending in the +x direction. That is, the guide groove GT11 includes a portion SE11 extending in a direction other than the y direction. Inside the guide groove GT11, a branched wiring 260 bent according to the shape of the guide groove GT11 is arranged.

[0052] The guide groove GT12 in FIG. 13 includes a portion extending from the middle part MP in the -y direction, a portion that bends obliquely in the -x direction midway, and a portion extending in the -y direction. That is, the guide groove GT11 includes a portion SE12 extending in a direction other than the y direction. Inside the guide groove GT12, a branched wiring 260 bent according to the shape of the guide groove GT12 is arranged.

[0053] (Effect) The longer the length of the specific wiring portion 260s, the more the inductance of the branched wiring 260 can be increased. In this embodiment, the length of the specific wiring portion 260s can be increased without increasing the size of the magnetic body portion 271 by the portion of the guide groove extending in a direction other than the y direction. While suppressing an increase in the size of the noise filter 201, it becomes possible to increase the adjustment range of the inductance of the branched wiring 260.

[0054] The exit position EX, which is the position where the branched wiring 260 is drawn out from the magnetic body portion 271, can be arbitrarily adjusted. Since interference with other wirings and members can be avoided, it becomes possible to enhance the flexibility of the design of the noise filter 201.

[0055] (Modification of Example 4) The technology of Example 4 is applicable to magnetic cores with various structures. For example, it may be applied to the magnetic body portion 71 (FIG. 5) in Example 1. In this case, the shape of the notch SL may be the same as the shape of the guide grooves GT11 and GT12.

[0056] As described above, specific examples of the present invention have been described in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. Also, the technical elements described in this specification or the drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Further, the technology illustrated in this specification or the drawings can achieve a plurality of purposes simultaneously, and has technical utility by achieving one of those purposes itself.

[0057] (Modified Example) The shape of the magnetic core 70 is not limited to the UI core described in this specification as long as it can enclose the first conductive wire, the second conductive wire, and the specific wiring portion all at once, and can have various shapes. For example, cores with various shapes such as EI cores can be used.

[0058] The number and arrangement positions of the via wirings and capacitors are examples. Also, by arranging a plurality of via wirings in parallel connection, the resistance of the via wirings may be reduced. In addition, in the noise filter of this specification, four parallel capacitors are used, but it is also possible to use one capacitor.

[0059] Note that the technology disclosed in this specification is not limited to the example of the LCL-configuration T-type noise filter, and is also applicable to other types of noise filters.

[0060] The aspects of this technology are listed below. [Aspect 1] A winding having a first terminal and a second terminal, and a first region and a second region that overlap each other so that current flows in the same direction, A branched wiring having a first wiring end portion and a second wiring end portion, wherein the first wiring end portion is connected to the first region, and the second wiring end portion is connected to a reference potential portion, the branched wiring, A capacitor disposed on the path of the branched wiring, A magnetic body disposed so as to surround at least a part of the first region and the second region and to surround a part of the branched wiring, and The winding includes a first conductive wire connecting from the first terminal to an intermediate portion to which the first wiring end portion is connected, and a second conductive wire connecting from the intermediate portion to the second terminal, The first region includes a specific region surrounded by the magnetic body, The first wiring end portion is located within the specific region, Noise filter. [Aspect 2] The noise filter according to aspect 1, wherein the magnetic body is configured to magnetically couple the first conductive wire and the second conductive wire, and reduce the equivalent series inductance of the capacitor and the parasitic inductance of the branch wiring by the mutual inductance generated therebetween. [Aspect 3] The noise filter according to aspect 1 or 2, wherein the position where the first wiring end is connected to the first region is configured to be changeable in the longitudinal direction of the first region. [Aspect 4] The magnetic body includes a first magnetic body portion and a second magnetic body portion. The first magnetic body portion includes a first columnar portion and a second columnar portion arranged opposite to each other, and a connecting portion connecting between one ends of the first columnar portion and the second columnar portion. A groove portion extending in a first direction is formed between the first columnar portion and the second columnar portion. The second magnetic body portion is arranged opposite to the other ends of the first columnar portion and the second columnar portion. At least a part of the first region and the second region, and the first wiring end are arranged inside the groove portion blocked by the second magnetic body portion. The branch wiring has a specific wiring portion that is a portion surrounded by the magnetic body. The specific wiring portion extends from the first wiring end in a second direction orthogonal to the first direction and passes through a region where the other end of the first columnar portion and the second magnetic body portion face each other. The noise filter according to any one of aspects 1 - 3. [Aspect 5] When viewed from a direction perpendicular to the first end face located at the other end of the first columnar portion, a part of the first end face overlaps with the specific wiring portion. The noise filter according to aspect 4, wherein the area of the region of the first end face that does not overlap with the specific wiring portion is substantially the same as the area of the second end face located at the other end of the second columnar portion. [Aspect 6] The specific wiring portion of the branch wiring includes a portion extending in a direction other than the second direction, the noise filter according to aspect 4 or 5. [Aspect 7] A gap is formed between the first end face located at the other end of the first columnar portion and the second magnetic body portion. The specific wiring portion is disposed in the gap, the noise filter according to any one of aspects 4-6. [Aspect 8] The noise filter further includes an insulating spacer disposed in the gap. The spacer is disposed in a region within the first end face where the specific wiring portion does not exist when viewed from a direction perpendicular to the first end face, the noise filter according to aspect 7. [Aspect 9] A guide groove extending in the second direction is formed in the first end face located at the other end of the first columnar portion. The specific wiring portion is disposed inside the guide groove, the noise filter according to any one of aspects 4-6. [Aspect 10] The noise filter further includes a substrate having two through holes. The substrate includes two through holes arranged side by side in the second direction, and the two through holes are disposed at positions facing each other with the first region and the second region interposed therebetween. The first magnetic body portion and the second magnetic body portion are combined through the two through holes. The branch wiring is disposed on the substrate, the noise filter according to any one of aspects 4-9.

Description of reference numerals

[0061] 1: Noise filter 2: Coil 15: Ground plate 31, 32: Capacitor 60: Branch wiring 61: First branch wiring 61E1: First wiring end 62: Second branch wiring 62E2: Second wiring end 70: Magnetic core 71: Magnetic part 72: Magnetic part A1: First region A2: Second region E1: Output terminal E2: Input terminal CW1: First conductive wire CW2: Second conductive wire MP: Intermediate part SA: Specific region

Claims

1. A winding having a first terminal and a second terminal, and having a first region and a second region that overlap each other so that current flows in the same direction, A branched wiring having a first wiring end portion and a second wiring end portion, wherein the first wiring end portion is connected to the first region, and the second wiring end portion is connected to a reference potential portion, the branched wiring; A capacitor disposed on the path of the branched wiring; A magnetic body that surrounds at least a part of the first region and the second region and is disposed so as to surround a part of the branched wiring; Comprising, The winding includes a first conductive wire connecting from the first terminal to an intermediate portion to which the first wiring end portion is connected, and a second conductive wire connecting from the intermediate portion to the second terminal; The first region includes a specific region surrounded by the magnetic body; The first wiring end portion is located within the specific region; Noise filter.

2. The noise filter according to claim 1, wherein the magnetic body is configured to magnetically couple the first conductive wire and the second conductive wire, and reduce the equivalent series inductance of the capacitor and the parasitic inductance of the branched wiring by the mutual inductance generated therebetween.

3. The noise filter according to claim 1, wherein the position where the first wiring end portion is connected to the first region is configured to be changeable in the longitudinal direction of the first region.

4. The magnetic body includes a first magnetic body portion and a second magnetic body portion; The first magnetic body portion includes a first columnar portion and a second columnar portion that are disposed opposite to each other, and a connecting portion that connects between one end of the first columnar portion and one end of the second columnar portion. A groove portion extending in a first direction is formed between the first columnar portion and the second columnar portion; The second magnetic body portion is disposed opposite to the other end of the first columnar portion and the other end of the second columnar portion; At least a part of the first region and the second region, and the first wiring end portion are disposed inside the groove portion blocked by the second magnetic body portion; The branched wiring has a specific wiring portion that is a portion surrounded by the magnetic body; The specific wiring portion extends from the first wiring end portion in a second direction orthogonal to the first direction, and passes through a region where the other end of the first columnar portion and the second magnetic body portion face each other. The noise filter according to claim 1.

5. When viewed from a direction perpendicular to the first end face located at the other end of the first columnar portion, a part of the first end face overlaps with the specific wiring portion. The area of the region of the first end face that does not overlap with the specific wiring portion is substantially the same as the area of the second end face located at the other end of the second columnar portion. The noise filter according to claim 4.

6. The specific wiring portion of the branched wiring includes a portion extending in a direction other than the second direction. The noise filter according to claim 4.

7. A gap is formed between the first end face located at the other end of the first columnar portion and the second magnetic body portion. The specific wiring portion is disposed in the gap. The noise filter according to claim 4.

8. The noise filter further includes an insulating spacer disposed in the gap. The spacer is disposed in a region within the first end face where the specific wiring portion does not exist when viewed from a direction perpendicular to the first end face. The noise filter according to claim 7.

9. A guide groove extending in the second direction is formed in the first end face located at the other end of the first columnar portion. The specific wiring portion is disposed inside the guide groove. The noise filter according to claim 4.

10. The noise filter further includes a substrate having two through holes. The substrate includes two through holes arranged side by side in the second direction, and the two through holes are disposed at positions facing each other with the first region and the second region interposed therebetween. The first magnetic body portion and the second magnetic body portion are combined via the two through holes. The branched wiring is disposed on the substrate. The noise filter according to claim 4.

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