Inductor and DC-DC converter including same

Abstract

To provide an inductor which is further reduced in coupling between coil conductors.SOLUTION: An inductor 10 includes: a magnetic core 100 formed by laminating a plurality of soft magnetic thin bands 131 in a Z direction; and first and second coil conductors 110, 120 respectively inserted into first and second penetration holes 101, 102 that penetrate through the magnetic core 100 in the Z direction and that are arranged in an X direction. Each of the soft magnetic thin bands 131 is divided into a plurality of small pieces P by gaps G. When a1 represents an average interval of the gaps G in the X direction and a2 represents an average interval of the gaps G in a Y direction, a1 is smaller than a2. Therefore, the coupling coefficient between the first coil conductor 110 and the second coil conductor 120 is lowered.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an inductor and a DC-DC converter including the inductor. [Background technology]

[0002] One of the circuit topologies for switching power supplies is the multiphase circuit, which is used as a power supply circuit suitable for handling large currents. Such multiphase switching power supplies use multiple coil conductors. If these multiple coil conductors are arranged on a single magnetic core to form a multiphase inductor, the mounting area and volume can be reduced.

[0003] Multi-phase inductors have multiple coil conductors arranged in one magnetic core, which poses the problem of coupling between the coil conductors. Coupling between the coil conductors reduces leakage inductance, which increases the current change in the inductor, i.e., the ripple current. For this reason, there is a demand for multi-phase inductors with reduced coupling between the coil conductors. For example, Patent Document 1 uses a magnetic core made of multiple laminated soft magnetic ribbons divided into small pieces to reduce the coupling between the coil conductors. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-026401 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure aims to provide an inductor with reduced coupling between coil conductors. [Means for solving the problem]

[0006] The inductor according to the present disclosure comprises a magnetic core formed by stacking a plurality of soft magnetic ribbons extending in first and second directions perpendicular to each other in a third direction perpendicular to the first and second directions, and first and second coil conductors that penetrate the magnetic core in the third direction and are inserted into first and second through holes arranged in the first direction, respectively, wherein each of the plurality of soft magnetic ribbons is divided into a plurality of small pieces by gaps, and where the average spacing of the gaps in the first direction is a1 and the average spacing of the gaps in the second direction is a2, a1 is smaller than a2. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide an inductor with reduced coupling between coil conductors. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic perspective view showing the appearance of an inductor 10 according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic diagram for explaining the structure of the magnetic core 100. As shown in FIG. [Figure 3] FIG. 3 is a schematic XY plan view of the soft magnetic ribbon 131. As shown in FIG. [Figure 4] FIG. 4 is a schematic plan view showing an enlarged portion of the soft magnetic ribbon 131. As shown in FIG. [Figure 5] FIG. 5 is a schematic diagram for explaining a method for forming the gap G in the soft magnetic ribbon 131. As shown in FIG. [Figure 6] FIG. 6 is a schematic perspective view showing the appearance of an inductor 20 according to the second embodiment of the present disclosure. [Figure 7] FIG. 7 is a circuit diagram of a DC-DC converter 30 using the inductor 10 or 20. [Figure 8] FIG. 8 is a table showing the results of the examples. [Figure 9] FIG. 9 is a table showing the results of the examples. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings.

[0010] FIG. 1 is a schematic perspective view showing the appearance of an inductor 10 according to a first embodiment of the present disclosure.

[0011] As shown in FIG. 1 , the inductor 10 according to the first embodiment includes a magnetic core 100 having a first through hole 101 and a second through hole 102, a first coil conductor 110 inserted into the first through hole 101, and a second coil conductor 120 inserted into the second through hole 102. The magnetic core 100 has a substantially rectangular parallelepiped outer shape, and the first and second through holes 101, 102 penetrate the magnetic core 100 in the Z direction, which is a third direction. The first through hole 101 and the second through hole 102 are arranged in the X direction, which is a first direction. The first through hole 101 and the second through hole 102 are positioned at the same position in the Y direction, which is a second direction, and are disposed approximately at the center of the magnetic core 100 in the Y direction.

[0012] The first coil conductor 110 and the second coil conductor 120 are both made of a good conductor such as copper (Cu), and both ends in the Z direction are exposed from the magnetic core 100. A terminal electrode 11 is provided at one end 111 in the Z direction of the first coil conductor 110, and a terminal electrode 12 is provided at one end 121 in the Z direction of the second coil conductor 120. Similarly, a terminal electrode 13 is provided at the other end 112 in the Z direction of the first coil conductor 110, and a terminal electrode 14 is provided at the other end 122 in the Z direction of the second coil conductor 120. The terminal electrodes 11 and 13 are used as input and output terminals of a first inductor formed by the first coil conductor 110, and the terminal electrodes 12 and 14 are used as input and output terminals of a second inductor formed by the second coil conductor 120.

[0013] As shown in FIG. 2, the magnetic core 100 has a structure in which a plurality of soft magnetic thin strips 131 extending in the XY direction are laminated in the Z direction through a non-magnetic material 132 such as resin. Thereby, the magnetic core 100 has a high magnetic permeability in the XY plane direction and a low magnetic permeability in the Z direction. The soft magnetic thin strips 131 constituting the magnetic core 100 are made of a high magnetic permeability metal material such as an amorphous alloy or a nanocrystalline alloy, and are divided into a plurality of small pieces P by a mesh-shaped gap G as shown in FIG. 3 which is a plan view of the XY plane. The gap G serves to adjust the magnetic permeability of the soft magnetic thin strip 131 in the XY plane direction, thereby preventing magnetic saturation of the inductor 10.

[0014] FIG. 4 is a schematic plan view showing an enlarged part of the soft magnetic thin strip 131.

[0015] As shown in FIG. 4, the gap G provided in the soft magnetic thin strip 131 is not random, and is mainly composed of a gap Gx extending substantially in the X direction and a gap Gy extending substantially in the Y direction. When the interval in the X direction between the gaps Gy adjacent in the X direction is a1 and the interval in the Y direction between the gaps Gx adjacent in the Y direction is a2, a1 < a2. That is, the interval in the Y direction of the gap Gx is wider than the interval in the X direction of the gap Gy. Preferably, the value of a1 / a2 is 0.9 or less, and more preferably, the value of a1 / a2 is 0.5 or more and 0.8 or less. The value of a1 is preferably in the range of 50 to 160 μm, and the value of a2 is preferably in the range of 63 to 200 μm.

[0016] Here, if the values ​​of a1 and a2 are not constant, average values ​​may be used. That is, a1 may be the average spacing in the X direction of gaps Gy adjacent in the X direction, and a2 may be the average spacing in the Y direction of gaps Gx adjacent in the Y direction. The average spacing a1 in the X direction of gaps Gy adjacent in the X direction and the average spacing a2 in the Y direction of gaps Gx adjacent in the Y direction can be obtained from an image captured in the XY plane of the soft magnetic ribbon 131. As an example, as shown in FIG. 4, an arbitrary determination region 131A is set in the image captured in the XY plane of the soft magnetic ribbon 131, and a virtual line Lx extending in the X direction and a virtual line Ly extending in the Y direction are set within this determination region 131A, and the values ​​of a1 and a2 can be determined based on the number of gaps Gy intersecting with the virtual line Lx and the number of gaps Gx intersecting with the virtual line Ly. In the example shown in FIG. 4, the number of gaps Gy intersecting with the virtual line Lx is 10, and the number of gaps Gx intersecting with the virtual line Ly is 7. Therefore, if the width of the determination region 131A in the X direction is Wx and the width of the determination region 131A in the Y direction is Wy, then a1 = Wx / 10 and a2 = Wy / 7. Multiple virtual lines Lx and Ly may be set. Multiple determination regions 131A may also be set, and their sizes are not particularly limited. The position at which the determination region 131A is set is also not particularly limited, but it is preferable to set it between the first through-hole 101 and the second through-hole 102.

[0017] 5, a method for forming a gap G having such a shape includes pressing the soft magnetic ribbon 131 against a roller 15 having a plurality of screw threads to form a gap G that is approximately parallel to the screw threads, and then rotating the soft magnetic ribbon 131 by 90° and performing the same process. In this case, the values ​​of a1 and a2 can be adjusted by changing the pitch of the screw threads, the order in which the soft magnetic ribbon 131 is pressed against the roller 15, etc.

[0018] Thus, in this embodiment, since the gap G provided in the soft magnetic thin strip 131 satisfies the condition a1 < a2, anisotropy occurs in the magnetic permeability. That is, the magnetic permeability in the X direction is lower than that in the Y direction. As a result, it is possible to reduce the coupling between the first coil conductor 110 and the second coil conductor 120 arranged in the X direction as compared with the case where there is no anisotropy in the magnetic permeability of the soft magnetic thin strip 131. Generally, it is considered that the coupling coefficient between the first coil conductor 110 and the second coil conductor 120 is preferably as close to zero as possible. However, when used as an inductor for a DC-DC converter, having a certain coupling coefficient results in smaller fluctuations in the output voltage. Specifically, the coupling coefficient between the first coil conductor 110 and the second coil conductor 120 is preferably in the range of 0.05 to 0.1.

[0019] Also, as shown in FIG. 3, when the width in the Y direction of the first and second through holes 101 and 102 is c, it is preferable that a2 < c is satisfied. According to this, a region where the gap Gx does not exist is not formed in the vicinity of the end surfaces in the X direction of the first and second through holes 101 and 102, and at least one gap Gx exists in the vicinity of the end surfaces in the X direction of the first and second through holes 101 and 102. Therefore, the magnetic permeability in the vicinity of the end surfaces in the X direction of the first and second through holes 101 and 102 does not locally increase, and it is possible to obtain a desired magnetic permeability. Note that FIG. 3 shows the case where the shape of the through hole is rectangular. In the case of a circular or elliptical shape, the maximum width in the Y direction is defined as c.

[0020] Furthermore, as shown in FIG. 3 , if the distance in the X direction between the edge E of the magnetic core 100 in the X direction and the ends of the first and second through holes 101 and 102 closest to the edge E is d, and the distance in the X direction between the first through hole 101 and the second through hole 102 is 2e, the value of a1 / a2 described above is preferably 0.9 times or less than the value of d / e. Here, in order to reduce the size of the magnetic core 100 in the X direction while keeping the distance d fixed, it is necessary to reduce the distance 2e, which increases the value of d / e. However, reducing the distance 2e strengthens the coupling between the first coil conductor 110 and the second coil conductor 120. To reduce the size of the magnetic core 100 in the X direction while keeping the coupling between the first coil conductor 110 and the second coil conductor 120 at 0.1 or less, it is sufficient to set the value of a1 / a2 to 0.9 times or less than the value of d / e. In other words, by making the value of a1 / a2 sufficiently small, it is possible to reduce the size of the magnetic core 100 in the X direction while keeping the coupling between the first coil conductor 110 and the second coil conductor 120 at 0.1 or less.

[0021] The distance d includes the distance d in the X direction between one edge E (positive side) of the magnetic core 100 in the X direction and the second through hole 102 closer to the one edge E, and the distance d in the X direction between the other edge E (negative side) of the magnetic core 100 in the X direction and the first through hole 101 closer to the other edge E, and these are set to be equal to each other. However, errors due to manufacturing variations are assumed to be included in the equal range. Furthermore, the distance 2e in the X direction between the first through hole 101 and the second through hole 102 is the distance from the edge of the first through hole 101 on the second through hole 102 side to the edge of the second through hole 102 on the first through hole 101 side.

[0022] FIG. 6 is a schematic perspective view showing the appearance of an inductor 20 according to the second embodiment of the present disclosure.

[0023] 6, the inductor 20 according to the second embodiment includes a magnetic core 100 having first to fourth through holes 101 to 104, a first coil conductor 210 inserted into the first and third through holes 101 and 103, and a second coil conductor 220 inserted into the second and fourth through holes 102 and 104. The first to fourth through holes 101 to 104 all pass through the magnetic core 100 in the Z direction. The first through hole 101 and the second through hole 102 are arranged in the X direction, the third through hole 103 and the fourth through hole 104 are arranged in the X direction, the first through hole 101 and the third through hole 103 are arranged in the Y direction, and the second through hole 102 and the fourth through hole 104 are arranged in the Y direction.

[0024] The first coil conductor 210 has a section 211 inserted into the first through hole 101, a section 212 inserted into the third through hole 103, and a section 213 connecting the sections 211 and 212. The first coil conductor 210 forms a one-turn coil by continuously connecting the sections 211, 213, and 212. Similarly, the second coil conductor 220 has a section 221 inserted into the second through hole 102, a section 222 inserted into the fourth through hole 104, and a section 223 connecting the sections 221 and 222. The second coil conductor 220 forms a one-turn coil by continuously connecting the sections 221, 223, and 222. The Z-direction tips of the sections 211 and 212 protruding from the magnetic core 100 are used as input and output terminals of a first inductor formed by the first coil conductor 210, and the Z-direction tips of the sections 221 and 222 protruding from the magnetic core 100 are used as input and output terminals of a second inductor formed by the second coil conductor 220. The Z-direction tips of the sections 211, 212, 221, and 222 protruding from the magnetic core 100 may further include a section extending in the in-plane direction of the XY plane. This makes it easier to connect the inductor 20 to pads on a board when mounting it on the board.

[0025] Also in this embodiment, similar to the first embodiment, by satisfying the relationship of a1 < a2 for the gap G provided in the soft magnetic ribbon 131 constituting the magnetic core 100, it becomes possible to suppress the coupling between the first coil conductor 210 and the second coil conductor 220.

[0026] As illustrated by the inductor 20 according to this embodiment, each coil conductor may have a shape inserted into a plurality of through holes. Also, the cross-section of the coil conductor and the cross-section of the through hole do not have to be rectangular, and may be circular as shown in FIG. 6.

[0027] FIG. 7 is a circuit diagram of a DC-DC converter 30 using the inductor 10 or 20.

[0028] The DC-DC converter 30 shown in FIG. 7 includes a pair of input terminals 51 and 52, a pair of output terminals 53 and 54, a switching transistor SW1 and an inductor L1 connected in series in this order between the input terminal 51 and the output terminal 53, a switching transistor SW2 and an inductor L2 connected in series in this order between the input terminal 51 and the output terminal 53, and a capacitor C1 connected between the output terminals 53 and 54. The circuit composed of the switching transistor SW1 and the inductor L1 and the circuit composed of the switching transistor SW2 and the inductor L2 are connected in parallel between the input terminal 51 and the output terminal 53. The input terminal 52 and the output terminal 54 constitute a ground line. A diode D1 is connected in the reverse direction between the connection point of the switching transistor SW1 and the inductor L1 and the ground line, and a diode D2 is connected in the reverse direction between the connection point of the switching transistor SW2 and the inductor L2 and the ground line. The switching transistors SW1 and SW2 are alternately turned on and off by a control circuit (not shown), whereby an output voltage Vout obtained by stepping down the input voltage Vin is generated.

[0029] In the DC-DC converter 30 having such a configuration, the above-mentioned inductor 10 or 20 is used as the inductors L1 and L2. For example, the first coil conductors 110 and 210 configure one inductor L1, and the second coil conductors 120 and 220 configure the other inductor L2. This makes it possible to reduce the number of parts configuring the DC-DC converter 30.

[0030] The above describes preferred embodiments of the present disclosure, but the present disclosure is not limited to the above embodiments, and various modifications are possible within the scope of the present disclosure, and it goes without saying that these modifications are also included within the scope of the present disclosure.

[0031] The technology according to the present disclosure includes, but is not limited to, the following configuration examples.

[0032] The inductor according to the present disclosure includes a magnetic core formed by stacking a plurality of soft magnetic ribbons extending in first and second directions orthogonal to each other in a third direction orthogonal to the first and second directions, and first and second coil conductors that penetrate the magnetic core in the third direction and are inserted into first and second through holes arranged in the first direction, each of the soft magnetic ribbons being divided into a plurality of small pieces by gaps, and where the average spacing of the gaps in the first direction is a1 and the average spacing of the gaps in the second direction is a2, a1 is smaller than a2. This makes it possible to provide a composite inductor with reduced coupling between the coil conductors.

[0033] The magnetic core may further have third and fourth through holes that penetrate in a third direction and are arranged in the first direction, the first and third through holes are arranged in a second direction, the second and fourth through holes are arranged in the second direction, the first coil conductor has a section inserted into the first through hole and a section inserted into the third through hole, and the second coil conductor has a section inserted into the second through hole and a section inserted into the fourth through hole, thereby making it possible to obtain a higher inductance.

[0034] The value of a1 / a2 may be 0.9 or less. According to this, it becomes possible to provide a composite inductor in which the coupling coefficient between coil conductors is 0.1 or less.

[0035] The value of a1 / a2 may be 0.5 or more and 0.8 or less. According to this, it becomes possible to make the coupling coefficient between coil conductors in the range of 0.05 to 0.1.

[0036] When the width in the second direction of the first and second through holes is c, a2 < c may be satisfied. According to this, the magnetic permeability in the vicinity of the end surface in the first direction of the first and second through holes does not become locally high, and it becomes possible to obtain a desired magnetic permeability.

[0037] When the distance in the first direction between the edge of the magnetic core in the first direction and the nearer one of the edges of the first and second through holes is d, and the distance in the first direction between the first through hole and the second through hole is 2e, the value of a1 / a2 may be 0.9 times or less the value of d / e. According to this, it becomes possible to reduce the size of the magnetic core in the first direction while suppressing the coupling between the first coil conductor and the second coil conductor to 0.1 or less.

[0038] The DCDC converter according to the present disclosure includes the above inductor. According to this, it becomes possible to provide a DCDC converter using a composite inductor in which the coupling coefficient between coil conductors is 0.1 or less.

Example

[0039] A plurality of soft magnetic thin strips 131 having different structures of the gap G were prepared, and samples having the same structure as the inductor 10 shown in FIG. 1 were actually manufactured. Then, for each sample, the coupling coefficient K between the first coil conductor 110 and the second coil conductor 120 was measured. For each sample, the size of the magnetic core 100 in the X direction was 6 mm, the size of the magnetic core 100 in the Y direction was 4.5 mm, the distance d was 0.5 mm, and the distance 2e was fixed at 1 mm. The results are shown in FIG.

[0040] As shown in Fig. 8, the smaller the value of a1 / a2, the lower the coupling coefficient K. Also, as shown in Fig. 9, which is a graph showing the relationship between the value of a1 / a2 and the coupling coefficient K, when the value of a1 / a2 is 0.9 or less, the coupling coefficient K is 0.1 or less. Also, when the value of a1 / a2 is 0.5 or more and 0.8 or less, the coupling coefficient K is in the range of 0.05 to 0.1. [Explanation of symbols]

[0041] 10,20 Inductor 11~14 Terminal electrode 15 Roller 30 DC-DC converter 51 Input terminal 51,52 Input terminals 53,54 Output terminals 100 magnetic cores 101 First through hole 102 Second through hole 103 Third Through Hole 104 4th Through Hole 110 first coil conductor 111 One end of first coil conductor 112 other end of first coil conductor 120 Second coil conductor 121 One end of second coil conductor 122 other end of second coil conductor 131 Soft magnetic ribbon 131A Judgment area 132 Non-magnetic materials 210 First coil conductor Section 211~213 220 Second coil conductor Section 221~223 C1 capacitor D1, D2 diodes E-edge G, Gx, Gy gap L1, L2 inductors Lx,Ly virtual lines P small piece SW1, SW2 switching transistors

Claims

1. a magnetic core formed by laminating a plurality of soft magnetic ribbons extending in first and second directions perpendicular to each other in a third direction perpendicular to the first and second directions; first and second coil conductors that penetrate the magnetic core in the third direction and are inserted into first and second through holes that are arranged in the first direction, Each of the soft magnetic ribbons is divided into a plurality of small pieces by gaps, When the average interval of the gap in the first direction is a1 and the average interval of the gap in the second direction is a2, a1 is smaller than a2, the value of a1 / a2 is 0.9 or less, An inductor, wherein a coupling coefficient between the first coil conductor and the second coil conductor is 0.1 or less.

2. the magnetic core further includes third and fourth through holes that penetrate in the third direction and are arranged in the first direction, the first and third through holes are arranged in the second direction; the second and fourth through holes are arranged in the second direction, the first coil conductor has a section inserted into the first through hole and a section inserted into the third through hole, The inductor according to claim 1 , wherein the second coil conductor has a section inserted into the second through hole and a section inserted into the fourth through hole.

3. 3. The inductor according to claim 1, wherein the value of a1 / a2 is 0.5 or more and 0.8 or less.

4. The inductor according to claim 1 , wherein a2<c is satisfied, where c is the width of the first and second through holes in the second direction.

5. A magnetic core formed by stacking a plurality of soft magnetic ribbons extending in first and second directions perpendicular to each other in a third direction perpendicular to the first and second directions; first and second coil conductors that penetrate the magnetic core in the third direction and are inserted into first and second through holes that are arranged in the first direction, Each of the soft magnetic ribbons is divided into a plurality of small pieces by gaps, When the average interval of the gap in the first direction is a1 and the average interval of the gap in the second direction is a2, a1 is smaller than a2, An inductor wherein the value of a1 / a2 is 0.9 times or less the value of d / e, where d is the distance in the first direction between the edge of the magnetic core in the first direction and the first and second through holes closest to the edge, and 2e is the distance in the first direction between the first through hole and the second through hole.

6. The magnetic core further has third and fourth through holes that penetrate in the third direction and are arranged in the first direction; the first and third through holes are arranged in the second direction; the second and fourth through holes are arranged in the second direction, the first coil conductor has a section inserted into the first through hole and a section inserted into the third through hole, The inductor according to claim 5 , wherein the second coil conductor has a section inserted into the second through hole and a section inserted into the fourth through hole.

7. An inductor as described in claim 5 or 6, wherein the value of a1 / a2 is 0.9 or less.

8. An inductor as described in claim 7, wherein the value of a1 / a2 is greater than or equal to 0.5 and less than or equal to 0.

8.

9. An inductor described in any one of claims 5 to 8, wherein when the width of the first and second through holes in the second direction is c, a2 < c is satisfied.

10. A DC-DC converter comprising the inductor according to any one of claims 1 to 9.

Images