JP2019201084A - Coil part, circuit board, and power supply device - Google Patents

Abstract

To provide a coil part that is less susceptible to magnetic saturation and can reduce leakage magnetic flux without increasing the size.SOLUTION: A coil part used for multiphase transformer coupling includes multiple independent coils and one or more magnetic cores, the magnetic core includes a plurality of outer leg portions each having a pair of outer leg pieces in which at least a portion of the coil is arranged and arranged in series and a gap interposed between the pair of outer leg pieces, a central leg portion having a portion disposed between any two of the outer leg portions and no intervening gap, and a pair of connecting portions that connect the plurality of outer leg portions and the central leg portion in a parallel state, and the relative permeability of the center leg portion is smaller than the relative permeability of each of the outer leg portions.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a coil component, a circuit board, and a power supply device.

  As coil parts including a coil and a magnetic core, a PFC choke coil for interleaving in Patent Document 1, a composite reactor for a multi-phase converter in Patent Document 2, a coupling transformer provided in a DC-DC converter in Patent Document 3 are known. Yes. The coil components of Patent Documents 1 to 3 include two independent coils and one magnetic core.

  The choke coil of Patent Document 1 includes a C-shaped first core portion (outer leg portion) around which a first winding is wound, and a C-shaped second core portion around which a second winding is wound ( An outer leg portion) and an I-shaped third core portion (central leg portion) disposed between the first core portion and the second core portion. In the choke coil, no gap is interposed between the core portions. The third core portion is made of a magnetic material having a relative initial permeability higher than that of the first core portion and the second core portion.

  The composite reactor of Patent Document 2 includes a C-shaped first magnetic core (outer leg) around which a first coil is wound and a C-shaped second magnetic core (outer leg) around which a second coil is wound. And an I-shaped shared magnetic core (center leg) disposed between the first magnetic core and the second magnetic core. In this composite reactor, a magnetic gap is interposed between the first magnetic core and the second magnetic core and the shared magnetic core. The shared magnetic core is composed of a ferrite core having an effective permeability larger than that of the first magnetic core and the second magnetic core.

  The coupling transformer of Patent Document 3 includes a magnetic core that is a combination of two coils and two E-shaped cores. The magnetic core includes a first magnetic leg (outer leg) on which the first coil is disposed, a second magnetic leg (outer leg) on which the second coil is disposed, and a central leg sandwiched between both magnetic legs. And a pair of connecting portions sandwiching them in parallel. The central leg is provided with a gap.

JP 2014-1223639 A JP 2014-78577 A JP2013-19821A

  Each coil is connected to a circuit component such as a switch via a wiring pattern or the like. Due to manufacturing errors of these wiring patterns and circuit components, variations in connection state, and the like, a large difference may occur in the current flowing through each coil. In Patent Documents 1 to 3, if each coil is arranged on each outer leg so that the magnetic flux generated by each coil is canceled in the same direction, the magnetic core may be magnetically saturated due to the current difference. The interlinkage component of the magnetic flux caused by the changing voltage applied to both coils mainly passes through the magnetic path (transformer-coupled magnetic path) from one outer leg to the other outer leg without passing through the central leg. For this reason, as the current difference between the coils increases, the amount of magnetic flux that attempts to pass through the transformer-coupled magnetic path increases. If the magnetic core is magnetically saturated, a predetermined step-up / step-down operation cannot be performed. Increasing the magnetic path area of the magnetic core can suppress magnetic saturation, but increases the size of the magnetic core and thus the size of the coil component. Furthermore, in Patent Document 3, a large gap in the center leg causes a magnetic flux generated by a direct current flowing through each coil to pass through a magnetic path from each outer leg to the center leg, so that a large amount of magnetic flux leaks from the center leg. There is a risk of becoming. If the leakage magnetic flux increases, it may cause noise and heat generation in peripheral parts.

  Accordingly, an object of the present invention is to provide a coil component that is less susceptible to magnetic saturation and can reduce leakage magnetic flux without increasing its size.

  Another object is to provide a circuit board and a power supply device.

The coil component according to the present disclosure is:
A coil component used for multiphase transformer coupling,
Comprising a plurality of independent coils and one or more magnetic cores;
The magnetic core is
A plurality of outer legs having a pair of outer leg pieces disposed in series and a gap interposed between the pair of outer leg pieces, wherein at least a part of the coil is disposed;
A central leg having a portion disposed between any two said outer legs, with no gaps interposed therebetween;
A pair of connecting portions for connecting the plurality of outer leg portions and the central leg portion in a parallel state;
The relative permeability of the central leg is smaller than the relative permeability of each outer leg.

  A circuit board according to the present disclosure includes a coil component according to the present disclosure.

  The power supply device according to the present disclosure includes the circuit board according to the present disclosure.

  The coil component according to the present disclosure is less likely to be magnetically saturated without increasing its size and can reduce leakage magnetic flux.

  The circuit board according to the present disclosure and the power supply device according to the present disclosure can satisfactorily perform a predetermined transformation operation.

1 is a perspective view illustrating an outline of a coil component according to Embodiment 1. FIG. It is a longitudinal cross-sectional view which shows the state cut | disconnected by the (II)-(II) cutting line of the coil components shown in FIG. It is a cross-sectional view which shows the state cut | disconnected by the (III)-(III) cutting line of the coil components shown in FIG. 6 is a perspective view illustrating an outline of a coil component according to Embodiment 2. FIG. It is a perspective view which shows the outline of the coil component which concerns on Embodiment 3. FIG. It is a top view which shows the outline of the circuit board which concerns on embodiment, and the power supply device which concerns on embodiment. Sample No. It is a distribution map which shows the distribution state of 1 magnetic flux density. Sample No. It is a longitudinal cross-sectional view which shows the outline of the sample for simulation of 101. FIG. Sample No. It is a distribution map which shows the distribution state of the magnetic flux density of 101.

<< Description of Embodiments of the Present Invention >>
First, the contents of the embodiments of the present invention will be listed and described.

(1) A coil component according to an aspect of the present invention includes:
A coil component used for multiphase transformer coupling,
Comprising a plurality of independent coils and one or more magnetic cores;
The magnetic core is
A plurality of outer legs having a pair of outer leg pieces disposed in series and a gap interposed between the pair of outer leg pieces, wherein at least a part of the coil is disposed;
A central leg having a portion disposed between any two said outer legs, with no gaps interposed therebetween;
A pair of connecting portions for connecting the plurality of outer leg portions and the central leg portion in a parallel state;
The relative permeability of the central leg is smaller than the relative permeability of each outer leg.

  According to the above configuration, each outer leg has a gap, and the relative permeability of the center leg is smaller than the relative permeability of the outer leg, so that the magnetic force can be obtained without interposing the gap in the center leg. It is easy to suppress saturation. Therefore, since it is not necessary to increase the magnetic path area in order to suppress magnetic saturation, it is possible to suppress an increase in the size of the magnetic core and, in turn, an increase in the size of the core component. Since the gaps of the outer legs are arranged in the coils, the leakage magnetic flux from the gaps hardly leaks outside the coil components. And since the gap is not interposed in the center leg, the leakage magnetic flux from the center leg can be reduced. Thereby, generation | occurrence | production of noise and heat_generation | fever of a peripheral component can be suppressed.

(2) As one form of the coil component,
It is mentioned that the cross-sectional area of the said center leg part is smaller than the cross-sectional area of each said outer leg part.

  According to said structure, compared with the case where the cross-sectional area of a center leg part is larger than the cross-sectional area of each outer side leg part, it is easy to make a magnetic core small, and it is easy to make a coil component small.

(3) As one form of the coil component,
It is mentioned that the total of the coupling coefficients of an arbitrary coil and the remaining coils among the plurality of coils is 0.7 or more.

  According to the above configuration, it is possible to construct a circuit board in which the increase amount of the ripple current due to the decrease in the coupling coefficient is small and the influence of the ripple current is small.

(4) As one form of the coil component,
Each of the connecting portions is formed in series without a gap,
One of the pair of outer leg pieces and one of the pair of connecting portions in each of the outer leg portions are integrally formed,
The other of the pair of outer leg pieces and the other of the pair of connecting portions in each of the outer leg portions are integrally formed,
It is mentioned that the said center leg part is a molded object independent of the said outer side leg part and the said connection part.

  According to the above configuration, a magnetic core is constructed by combining a pair of molded bodies in which one of the outer leg pieces and one of the connecting portions of each outer leg portion are integrally formed and the central leg portion. This reduces the number of magnetic core parts. Therefore, the assembly workability of the magnetic core can be improved, and as a result, the assembly workability of the coil component can be improved. In particular, since the connecting portions between the constituent members of the magnetic core can be two places of the central leg portion and the pair of connecting portions, the combination workability of the magnetic core is excellent. Since the pair of molded bodies and the central leg are independent molded bodies, the specifications of the two molded bodies (such as constituent materials and blends thereof) can be easily changed so that the central leg can be easily compared with the outer legs. The relative permeability can be reduced.

(5) As one form of the coil component,
Having one said magnetic core,
It is mentioned that each said coil is arrange | positioned at each said outer leg part.

  According to said structure, it is hard to saturate magnetically and it can reduce a leakage magnetic flux, without enlarging.

(6) As one form of the coil component,
A plurality of the magnetic cores arranged in an annular shape;
Each of the magnetic cores has the two outer legs,
In the coil, the one outer leg portion of one of the magnetic cores and the one outer leg portion of the other magnetic core among the adjacent magnetic cores are collectively housed inside. It is done.

  According to said structure, it is hard to saturate magnetically and it can reduce a leakage magnetic flux, without enlarging.

(7) A circuit board according to an aspect of the present invention includes:
Any one coil part of said (1) to said (6) is provided.

  According to the above configuration, since the coil component is less likely to be magnetically saturated due to the current difference flowing through each coil and the increase amount of the ripple current is small, if used in a transformer circuit such as a multi-phase transformer coupled step-up / down circuit. The predetermined transformation operation can be performed satisfactorily. Further, since the coil component having a small leakage magnetic flux is provided, the noise is small and it is difficult to generate heat.

(8) A power supply device according to one embodiment of the present invention includes:
The circuit board of (7) is provided.

  According to said structure, since it comprises the said circuit board, if it uses for converters, such as a polyphase transformer coupling type | mold step-up / step-down converter, a predetermined transformation operation can be performed favorably.

<< Details of Embodiment of the Present Invention >>
Details of embodiments of the present invention will be described below with reference to the drawings. The same code | symbol in a figure shows the same name thing. The following description will be given in the order of a coil component, a circuit board including the coil component, and a power supply device including the circuit board. The coil component will be described in detail after describing the overall outline, followed by details of the configuration of each embodiment.

[Coil parts]
[Overview]
The coil component 1 according to the embodiment is used for multiphase transformer coupling, and includes a plurality of independent coils 2 and one or more magnetic cores 3 (FIG. 1 and the like). The combination of the number of coils 2 and magnetic cores 3 in the coil component 1 may be a plurality of coils 2 and one magnetic core 3 as in the first and second embodiments (FIGS. 1 and 4), as in the third embodiment. In addition, a plurality of coils 2 and a plurality of magnetic cores 3 can be formed (FIG. 5). The magnetic core 3 includes a plurality of outer leg portions 31, one central leg portion 32, and a pair of connecting portions 33 that connect the plurality of outer leg portions 31 and the central leg portion 32 in parallel. The number of outer legs 31 can be appropriately selected according to the combination of the number of coils 2 and magnetic cores 3, and can be the same as the number of coils 2 as in the first and second embodiments (FIGS. 1 and 4). As in the third embodiment, the number can be larger than that of the coil 2 (for example, twice the number of coils) (FIG. 5). The center leg 32 has a portion disposed between any two outer legs 31. One of the features of the coil component 1 according to the embodiment is that the outer leg 31 has a specific configuration, the central leg 32 has a specific configuration, and the outer leg 31 and the central leg 32 have a specific configuration. The relative permeability (magnetic characteristics) satisfies a specific relationship.

[Embodiment 1]
The coil component 1 according to the first embodiment will be described mainly with reference to FIGS. 1 to 3 (as appropriate, FIG. 6). The coil component 1 according to the first embodiment is used for two-phase transformer coupling, and includes two independent coils 2 and one magnetic core 3. 1 to 3, the coil 2 is shown in a simplified manner for convenience of explanation.

(coil)
Each coil 2 includes a cylindrical winding portion 21 formed by winding a winding in a spiral shape, and a pair of lead portions 22 (FIG. 6) of the winding extending from the winding portion 21. Each winding portion 21 is disposed on each outer leg portion 31 of the magnetic core 3 described later. Each extraction part 22 is connected to the wiring pattern 51 etc. of the circuit board 5 (FIG. 6). Each coil 2 is connected to an external device (not shown) such as a power source for supplying power via a wiring pattern 51 (FIG. 6). The coils 2 are arranged so that when energized, the magnetic fluxes generated by the currents flowing through the coils 2 are canceled in the same direction. That is, a current is passed through each coil 2 so as to have such a magnetic flux flow.

  For each winding, a coated wire having an insulating coating on the outer periphery of the conductor wire can be suitably used. In addition, a litz wire may be used for each winding. Examples of the conductor wire include a flat wire and a round wire. If the conductor wire is a flat wire, the space factor can be easily increased, and the small coil 2 can be easily obtained. A coil in which the conductor wire is a flat wire has better shape retention than the litz wire, and can retain the cylindrical shape even when manufactured independently of the magnetic core 3. Examples of the constituent material of the conductor wire include copper, aluminum, and alloys thereof. As a constituent material of the insulating coating, for example, a resin such as polyamide imide called enamel can be cited. Each winding uses a covered rectangular wire in this example. The specifications (configuration material, size (width and thickness), cross-sectional area, etc.) of each winding can be selected as appropriate, and are the same in this example.

  The shape of each winding part 21 is a cylindrical shape in this example, but may be a rectangular tube shape. The specifications (winding diameter, number of windings, natural length, etc.) of each winding part 21 can be selected as appropriate, and are the same in this example. Each coil 2 is an edgewise coil in which a coated rectangular wire is edgewise wound. Such a cylindrical edgewise coil is easy to manufacture even when the winding diameter is relatively small.

(Magnetic core)
The magnetic core 3 includes a soft magnetic material and forms a closed magnetic circuit. The magnetic core 3 includes a plurality of outer leg portions 31, one central leg portion 32, and a pair of connecting portions 33.

<Outside leg>
Each outer leg 31 is provided with at least a part of the coil 2 (winding portion 21). In this example, each outer leg 31 has all the coils 2 (winding portions 21) disposed therein. The number of outer legs 31 is two, which is the same as the number of coils 2 in this example. The shape of each outer leg part 31 is a shape along the inner peripheral shape of each winding part 21, and is a columnar shape in this example. The sizes of the outer leg portions 31 are the same. Each outer leg 31 has a pair of outer leg pieces 311 arranged in series, and a gap 312 interposed between the pair of outer leg pieces (FIG. 2). By having each gap 312, it is easy to suppress magnetic saturation even when used for a coil component for large current applications.

  The pair of outer leg pieces 311 in each outer leg portion 31 have the same shape and the same size. In this example, one of the pair of outer leg pieces 311 of each outer leg portion 31 is integrally formed with one of a pair of connecting portions 33 described later, and the other of the pair of outer leg pieces 311 is a pair of connecting portions. It is integrally formed with the other 33. If it does so, the magnetic core 3 can be constructed | assembled by combining three members of a pair of integrally molded object and the center leg part 32. FIG. Therefore, since the number of parts can be reduced, it is easy to improve the assembling workability of the magnetic core 3, and as a result, the assembling workability of the coil part 1 is easily improved.

  Each gap 312 is located in the coil 2. As a result, the leakage magnetic flux from each gap 312 is difficult to leak to the outside of the coil component 1, so that the generation of noise and heat generation in peripheral components can be suppressed. Examples of each gap 312 include a gap material made of a material having a relative permeability lower than that of the outer leg piece 311 in addition to an air gap. Examples of the constituent material of the gap material include ceramics such as alumina, nonmagnetic materials such as resin (for example, PPS resin), and composite materials including soft magnetic powder and resin.

  The gap length of each gap 312 can be appropriately selected according to a desired coupling coefficient, which will be described later, although it depends on the ratio of the relative permeability of each outer leg 31 and the relative permeability of the center leg 32. The gap length can be made relatively short, for example, 1 mm or less, further 0.5 mm or less, particularly 0.25 mm or less. If it does so, it is easy to reduce the leakage magnetic flux from each outer leg part 31. FIG. For example, the gap length is preferably 0.07 mm or more, more preferably 0.08 mm or more, and particularly preferably 0.1 mm or more. Then, it is easy to suppress magnetic saturation.

<Center leg>
The center leg part 32 has a part arrange | positioned between the two outer leg parts 31 (FIG. 1, FIG. 3). Unlike the outer leg 31, the central leg 32 is not provided with the coil 2 and has no gap. For this reason, leakage magnetic flux due to the gap is not substantially generated, so that generation of noise and heat generation of peripheral components (other components on the circuit board 5 (FIG. 6)) can be suppressed.

  The central leg portion 32 is connected to each of the pair of connecting portions 33 without substantially interposing a gap (FIG. 2). Here, “substantially not interposing a gap” means that there is no gap between the center leg portion 32 and the connecting portion 33, and there is an unavoidable gap or the center leg. The case where the adhesive 4 is used to connect the portion 32 and the connecting portion 33 is also included. This is because the gap and the adhesive 4 do not substantially affect the relative magnetic permeability of the entire magnetic core 3. The fact that there is no substantial effect means that the change in the relative permeability of the magnetic core 3 as a whole is within 10% of the case where there is no gap or adhesive 4 even if the gap or adhesive 4 is present. Say. In this example, the central leg portion 32 is a molded body independent of the outer leg portion 31 and the connecting portion 33, and is bonded to each of the pair of connecting portions 33 with the adhesive 4. Thus, since the connection location of the structural members of the magnetic core 3 is two locations of the center leg part 32 and a pair of connection part 33, it is excellent in the workability | operativity of the magnetic core 3. FIG. The thickness of each adhesive 4 is, for example, more than 0 mm and less than 0.07 mm, further 0.01 mm or more and 0.06 mm or less, and further 0.04 mm or more and 0.06 mm or less.

  The shape of the central leg 32 is preferably a columnar shape having a space along the space between the two coils 2 and sandwiched between the outer shapes of the two coils 2 (FIG. 3). The opposed surfaces (both side surfaces) of the central leg 32 to each coil 2 preferably have a surface that substantially follows the outer shape of each coil 2. If it does so, it will be easy to make the space | interval between the center leg part 32 and the coil 2 small and uniform, and it will be easy to reduce the coil component 1 in size. The shape (cross-sectional shape) of the central leg portion 32 is a substantially Erlenmeyer flask type (T-shaped) column shape in this example, and both side surfaces of the central leg portion 32 are curved surfaces along the outer shape of the coil 2. The curved surface is formed continuously, and has a straight surface along the direction of dividing between the outer leg portions 31. The shape (cross-sectional shape) of the central leg portion 32 may be a ribbon shape.

  The cross-sectional area of the central leg 32 is preferably smaller than the cross-sectional area of each outer leg 31 (FIG. 3). By doing so, the magnetic core 3 can be easily downsized, and the coil component 1 can be easily downsized. Specifically, when the outer leg portions 31 and the connecting portions 33 have the same shape and the same size, if the cross-sectional area of the central leg portion 32 is smaller than the cross-sectional area of the outer leg portions 31, the outer leg portions 31. The magnetic core 3 can be reduced in size compared with the case where it is larger than the cross-sectional area. The cross-sectional area of the central leg portion 32 is smaller than the cross-sectional area of each outer leg portion 31 when the cross-sectional areas of the plurality of outer leg portions 31 are different. Say that it is smaller than the cross-sectional area. For example, the cross-sectional area of the central leg 32 is preferably (cross-sectional area of the outer leg 31) × 0.95 times or less, more preferably (cross-sectional area of the outer leg 31) × 0.90 times or less. (Cross-sectional area of the outer leg 31) × 0.85 times or less is preferable. The cross-sectional area of the central leg 32 is preferably, for example, (cross-sectional area of the outer leg 31) × 0.5 times or more. If it does so, the cross-sectional area of the center leg part 32 is not too small. Each cross-sectional area refers to a cross section cut along a cutting line orthogonal to the magnetic path.

<Connecting part>
Each connecting portion 33 connects the plurality of outer leg portions 31 and the central leg portion 32 in a parallel state. The shape and size of each connecting portion 33 can be selected as appropriate within a range having a predetermined magnetic path cross-sectional area. In this example, they are the same shape and the same size. The shape of each connecting portion 33 is a horizontally long substantially octagonal flat plate shape, and is curved so that both lateral sides thereof are convex outward.

<Permeability relationship>
The relationship between the relative permeability of each outer leg 31 and the relative permeability of the center leg 32 satisfies “relative permeability of the center leg 32 <relative permeability of each outer leg 31”. Therefore, it is easy to suppress magnetic saturation without providing a gap in the central leg portion 32. Since it is not necessary to increase the magnetic path area in order to suppress the magnetic saturation, it is possible to suppress an increase in the size of the magnetic core 3 and hence an increase in the size of the coil component 1. In addition, since the gap is not interposed in the central leg portion, no leakage magnetic flux due to the gap is generated, so that generation of noise and heat generation in peripheral components can be suppressed. For example, the relative permeability of the connecting portion 33 is the same as the relative permeability of the outer leg portion 31.

  The relative permeability of each outer leg 31 can be appropriately selected according to the desired inductance. The relative permeability of the central leg 32 is set lower than the relative permeability of each outer leg 31 to such an extent that magnetic saturation can be suppressed according to the relative permeability of each outer leg 31. The ratio of the relative permeability of each outer leg 31 to the relative permeability of the center leg 32 (relative permeability of the center leg 32 / relative permeability of each outer leg 31) is, for example, 0.001 or more and 0 .2 or less. If the ratio of the relative permeability is 0.2 or less, magnetic saturation is easily suppressed. If the ratio of the relative permeability is 0.001 or more, the difference between the relative permeability of each outer leg 31 and the relative permeability of the center leg 32 is not excessively large, and therefore flows in each coil 2. The magnetic flux generated by the direct current is easy to pass from each outer leg 31 to the center leg 32. The ratio of the relative magnetic permeability is further 0.002 or more and 0.12 or less, and particularly 0.003 or more and 0.07 or less. The relative permeability of the outer leg 31 is, for example, 500 or more and 5000 or less, more preferably 800 or more and 4500 or less, and particularly preferably 1000 or more and 4000 or less. The relative permeability of the central leg portion 32 is, for example, 5 or more and 100 or less, further 10 or more and 90 or less, and particularly 12 or more and 70 or less.

<Constituent materials>
The constituent material of the outer leg portion 31, the central leg portion 32, and the connecting portion 33 is a molded body mainly composed of a soft magnetic material. Examples of the soft magnetic material include metals such as iron and iron alloys (eg, Fe—Si alloy, Fe—Ni alloy, etc.), nonmetals such as ferrite, and the like. The compacts are sintered compacts such as ferrite cores, compacted compacts formed by compression molding of soft magnetic powders and coating powders with insulating coatings, etc., and fluid mixtures containing soft magnetic powders and resins are solidified. Examples of the composite material molded body are as follows. The constituent materials (such as the type and content of the soft magnetic material) of the outer leg portion 31, the central leg portion 32, and the connecting portion 33 satisfy the above-described relative permeability magnitude relationship and a desired relative permeability ratio. It can be selected as appropriate.

  In this example, the constituent material of the outer leg portion 31 and the connecting portion 33 is a sintered body of a ferrite core, and the constituent material of the central leg portion 32 is a molded body of the composite material. By adjusting the content of the soft magnetic powder in the composite material, the relative permeability of the central leg 32 can be made lower than the relative permeability of the outer leg 31, and in particular, the desired relative permeability ratio described above can be set. Can be satisfied.

  The content of the soft magnetic powder in the central leg portion 32 is, for example, preferably 90% by volume or less, more preferably 80% by volume or less, and particularly preferably 70% by volume or less, when the whole is 100% by volume. If it does so, it will be easy to make the relative permeability of the center leg part 32 smaller than the outer side leg part 31, and it will be easy to satisfy | fill the ratio of the desired relative permeability mentioned above. The content of the soft magnetic powder in the central leg 32 is preferably 60% by volume or more, for example. If it does so, the relative magnetic permeability of the center leg part 32 will not become too low too much.

(Coupling coefficient)
Among the plurality of coils 2, any one of the coils 2 is a specific coil, a coupling coefficient of a coil pair formed by the specific coil and each of the remaining coils 2 is obtained, and the coupling coefficient of each coil pair is summed. It is preferable that the same coupling coefficient is derived by sequentially changing the specific coils for all the coils, and the total of the coupling coefficients of the respective coil pairs in each specific coil obtained is 0.7 or more. Then, the increase amount of the ripple current is small, and a multi-phase transformer coupled transformer circuit and the like that can stably perform transformation operations such as step-up and step-down over a long period can be constructed. The larger the total of the coupling coefficients, the easier it is to reduce the increase amount of the ripple current. Therefore, the total of the coupling coefficients is preferably 0.75 or more, 0.78 or more, or 0.8 or more. The coupling coefficient can be adjusted by the gap length of each outer leg 31, although it depends on the ratio between the relative permeability of each outer leg 31 and the relative permeability of the center leg 32.

The coupling coefficient k of each coil pair is obtained by k ² = M ² / (L1 × L2). L 1 is the self-inductance of one coil 2, L 2 is the self-inductance of the other coil 2, and M is the mutual inductance of both coils 2. Using commercially available simulation software or the like, correlation data between the coupling coefficient and the ripple current, correlation data between the gap length for each coupling coefficient and the energization current value, and the like can be obtained in advance. By using the correlation data, a more preferable coupling coefficient, gap length, operating current value, and the like can be easily selected according to desired requirements.

  In this example, since the number of the coils 2 is two, it is preferable that the coupling coefficient of the two coils 2 is 0.7 or more. By doing so, it is possible to construct a two-phase transformer-coupled transformer circuit or the like in which the increase amount of the ripple current is small and the transformer operation such as step-up and step-down can be stably performed over a long period of time.

[Embodiment 2]
With reference to FIG. 4, the coil component 1 which concerns on Embodiment 2 is demonstrated. The coil component 1 according to the second embodiment is the same as the coil component 1 according to the first embodiment in that the coil component 1 includes a plurality of independent coils 2 and one magnetic core 3. The coil component 1 according to the second embodiment is used for transformer coupling of three or more phases, and mainly includes the number of coils 2, the number of outer leg portions 31 provided in the magnetic core 3, and the shape of the central leg portion 32. This is different from the coil component 1 according to the first embodiment. Differences from the first embodiment will be mainly described, and description of similar configurations and similar effects will be omitted. This is the same in the third embodiment described later.

(Coil / magnetic core)
The coil component 1 of this example is used for three-phase transformer coupling, and includes three independent coils 2 and one magnetic core 3. Each coil 2 is the same as the coil 2 of the coil component 1 according to the first embodiment. The magnetic core 3 has three outer leg portions 31, one central leg portion 32, and a pair of connecting portions 33 that connect the three outer leg portions 31 and one central leg portion 32 in parallel. The shape of each connecting portion 33 is a triangular flat plate having the same shape, and the size of each connecting portion 33 is the same size.

  The three outer legs 31 are arranged at the positions of the vertices of the triangle. The shapes and sizes of the three outer legs 31 are cylindrical shapes having the same shape and the same size. Each outer leg 31 has a pair of outer leg pieces 311 and a gap 312 (see FIG. 2) interposed therebetween.

  The center leg 32 is arranged at the center of the triangle formed by the three outer legs 31 and has a portion interposed between any two outer legs 31. The shape of the central leg portion 32 can be appropriately selected according to the arrangement of the three outer leg portions 31. In this example, the shape is a triangular shape, and a circular arc shape (Y shape) with each side recessed toward the center. This arc is preferably along the outer shape of the coil 2. The opposing surface of each central leg 32 that faces each coil 2 is curved along the outer shape of each coil 2. The configuration of the center leg 32 is similar to that of the center leg 32 of the magnetic core 3 of the coil component 1 according to the first embodiment, and no gap is interposed therebetween. See). The relative permeability of the central leg 32 is smaller than the relative permeability of each outer leg 31.

(Coupling coefficient)
It is preferable that the sum of the coupling coefficients of an arbitrary coil 2 and another coil 2 is 0.7 or more. That is, in this example, in the three coils 2 (hereinafter referred to as the first, second, and third coils in order from the front side in FIG. 4 in the clockwise direction), all of the following (a) to (c) It is preferable that it is 0.7 or more. Then, like the first embodiment, it is possible to construct a three-phase transformer-coupled transformer circuit or the like in which the increase amount of the ripple current is small and the transformer operation such as step-up / step-down can be stably performed over a long period of time. The preferred range of the sum of the coupling coefficients, how to adjust the coupling coefficient, and how to obtain the coupling coefficient are as described in the first embodiment.
(A) Sum of coupling coefficient of first coil 2 and second coil 2 and coupling coefficient of first coil 2 and third coil 2 (b) of second coil 2 and third coil 2 Sum of coupling coefficient and coupling coefficient of second coil 2 and first coil 2 (c) Coupling coefficient of third coil 2 and first coil 2, and of third coil 2 and second coil 2 Total with coupling factor

[Embodiment 3]
With reference to FIG. 5, the coil component 1 which concerns on Embodiment 3 is demonstrated. The coil component 1 according to the third embodiment is the same as the coil component 1 according to the first embodiment in that it includes a plurality of independent coils 2. The coil component 1 according to the third embodiment is used for transformer coupling of three or more phases, and the number of coils 2 and the number of magnetic cores 3 are mainly different from the coil component 1 according to the first embodiment.

(Coil / magnetic core)
The coil component 1 of this example is used for three-phase transformer coupling, and includes three independent coils 2 and three (the same number as the coils 2) magnetic cores 3. The configuration of each magnetic core 3 is the same as the magnetic core 3 of the coil component 1 according to the first embodiment, and includes two outer leg portions 31, one central leg portion 32, and a pair of connecting portions 33.

  The shape and size of the three magnetic cores 3 are the same shape and the same size. The configuration of the central leg portion 32 in each magnetic core 3 is similar to the central leg portion 32 of the magnetic core of the coil component 1 according to the first embodiment. 4 (see FIG. 2). The relative permeability of the central leg 32 is smaller than the relative permeability of each outer leg 31, and the cross-sectional area is smaller than the cross-sectional area of each outer leg 31.

  The three magnetic cores 3 are connected by a coil 2 and arranged in an annular shape. Each coil 2 accommodates one outer leg 31 of one magnetic core 3 and one outer leg 31 of the other magnetic core 3 among the adjacent magnetic cores 3 in a lump. That is, a part of the coil 2 is disposed on each outer leg 31 of each magnetic core 3. Each coil 2 has a racetrack shape.

(Coupling coefficient)
It is preferable that the coupling coefficient between adjacent coils 2 with respect to an arbitrary magnetic core 3 is 0.7 or more. That is, in this example, in the three coils 2 (hereinafter referred to as the first, second, and third coils in order from the front side in FIG. 5 in the clockwise direction), all of the following (a) to (c) It is preferable that it is 0.7 or more. Then, as in the first embodiment, it is possible to construct a multi-phase transformer-coupled transformer circuit or the like in which the increase amount of the ripple current is small and the transformer operation such as step-up / step-down can be stably performed over a long period. The preferred range of the sum of the coupling coefficients, how to adjust the coupling coefficient, and how to obtain the coupling coefficient are as described in the first embodiment.
(A) Coupling coefficient between the first coil 2 and the second coil 2 (b) Coupling coefficient between the second coil 2 and the third coil 2 (c) The third coil 2 and the second coil 2 Coupling coefficient with one coil 2

[Usage]
The coil component 1 according to the embodiment can be used as one of component parts of a circuit board that performs multi-phase transformer coupling. Among them, the coil component 1 of the first embodiment is used as one of circuit board components that perform two-phase transformer coupling, and the coil components 1 of the second and third embodiments perform three-phase transformer coupling. It can be used as one of circuit board components.

[Function and effect]
In each of the coil components 1 according to the first to third embodiments, each outer leg 31 has a relatively small gap 312, and the relative permeability of the center leg 32 is higher than the relative permeability of each outer leg 31. Therefore, it is easy to suppress magnetic saturation even if no gap is interposed in the center leg portion 32. Therefore, since it is not necessary to increase the magnetic path area in order to suppress magnetic saturation, it is possible to suppress an increase in the size of the magnetic core 3 and further an increase in the size of the coil component 1. And since the gap is not interposed in the center leg part 32, since the leakage magnetic flux resulting from a gap does not arise, generation | occurrence | production of noise and heat_generation | fever of peripheral components can be suppressed.

[Circuit board]
With reference to FIG. 6, the circuit board 5 which concerns on embodiment is demonstrated. The circuit board 5 includes the coil component 1 according to the above-described embodiment. Although FIG. 6 illustrates the case where the coil component 1 according to the first embodiment is provided, the coil component 1 according to the second or third embodiment may be provided. In FIG. 6, a part of the circuit board 5 is partially shown in a case of the power supply device 6.

  The circuit board 5 includes a coil component 1, a substrate body 50 having one surface on which the coil component 1 and the like are placed, and a plurality of circuit boards 5 formed on the substrate body 50 and connected to a pair of lead portions 22 of each coil 2. Wiring pattern 51.

  The wiring pattern 51 supplies a predetermined power to each coil 2. The shape, arrangement state, and the like of the wiring pattern 51 can be appropriately selected as long as the lead portions 22 of the respective coils 2 can be connected. In FIG. 6, the wiring patterns 51 are formed in a straight line and are arranged substantially in parallel. When the plurality of wiring patterns 51 are arranged in parallel, it is easy to form a wiring pattern, and the manufacturability of the circuit board 5 is excellent.

  Examples of the constituent material of the substrate body 50 include various insulating materials. For example, the wiring pattern 51 may be formed of a copper foil or a metal plate such as a copper plate. For other configurations in the circuit board 5, known configurations can be used, and detailed description thereof is omitted. A known method such as soldering or screw connection can be used for connection between each drawing portion 22 and each wiring pattern 51.

(Use)
The circuit board 5 according to the embodiment can be used as one of the components of the power supply device 6 that performs multiphase transformer coupling. The circuit board 5 according to the embodiment is a DC-DC converter, and can be used for a multiphase translink type boost chopper circuit or the like.

(Function and effect)
The circuit board 5 according to the embodiment includes the coil component 1 that is less likely to be magnetically saturated due to a current difference flowing through each coil 2 and also has a small amount of increase in ripple current. Therefore, a transformer circuit such as a multiphase transformer-coupled step-up / down circuit When used in the above, a predetermined transformation operation can be performed satisfactorily. Moreover, since the coil component 1 with little leakage magnetic flux is provided, there is little noise and it is difficult to generate heat.

[Power supply unit]
With reference to FIG. 6, the power supply device 6 which concerns on embodiment is demonstrated. The power supply device 6 includes the circuit board 5 according to the embodiment. FIG. 6 illustrates the case where the coil component 1 provided on the circuit board 5 is the coil component 1 according to the first embodiment, but the coil component 1 provided on the circuit board 5 is the coil component 1 according to the second or third embodiment. It may be. For other configurations of the power supply device 6, known configurations can be used, and detailed description thereof is omitted.

(Use)
The power supply device 6 of the embodiment can be used for a converter mounted on a vehicle such as a hybrid vehicle, an electric vehicle, and a fuel cell vehicle.

(Function and effect)
The power supply device 6 according to the embodiment includes the circuit board 5 provided with the coil component 1 that is difficult to be magnetically saturated by the current flowing through each coil 2 and also has a small increase in ripple current. When used in a converter such as a buck-boost converter, a predetermined voltage transformation operation can be performed satisfactorily.

《Test example》
The amount of magnetic flux leakage due to the presence or absence of a gap in the central leg of the magnetic core of the coil component was investigated by simulation.

[Sample No. 1]
Sample No. The one coil component 1 is the same as the coil component 1 described in the first embodiment with reference to FIGS. 1 to 3, and includes two independent coils 2 and one magnetic core 3. The coil 2 is the same as the coil 2 of the coil component 1 according to Embodiment 1 described above. The magnetic core 3 has two (a pair of) outer leg portions 31, one central leg portion 32, and a pair of connecting portions 33.

  Each outer leg 31 has a pair of outer leg pieces 311 and a gap 312 therebetween. The cross-sectional areas of the pair of outer leg portions 31 are the same size. The gap length of the gap 312 is 0.1 mm. One of the pair of outer leg pieces 311 of each outer leg portion 31 is integrally formed with one of the connecting portions 33, and the other of the pair of outer leg pieces 311 is integrally formed with the other of the connecting portions 33. The constituent material of the pair of outer leg portions 31 and the pair of connection portions 33 is a ferrite core sintered body. The relative permeability of the pair of outer leg portions 31 and the pair of connecting portions 33 is 3000.

  The central leg portion 32 does not have a gap and is bonded to the pair of connecting portions 33 with the adhesive 4. The thickness of the adhesive 4 is 0.05 mm. The constituent material of the central leg portion 32 is a composite material obtained by solidifying a fluid mixture containing a soft magnetic material powder and a resin. The relative permeability of the central leg 32 is 20 which is smaller than the relative permeability (= 3000) of the pair of outer legs 31 and the pair of connecting portions 33.

  The cross-sectional area of the central leg portion 32 is smaller than the cross-sectional area of each outer leg piece 311 (outer leg portion 31). The cross-sectional area of the central leg portion 32 is the cross-sectional area of each outer leg piece 311 × 0.9 times.

[Sample No. 101]
Sample No. The coil component 100 of 101 includes two independent coils 200 and one magnetic core 300 as shown in FIG. Same as 1. FIG. 8 is a cross-sectional view showing a state where the coil component 100 is cut at the same position as the cross-sectional view shown in FIG. The coil 200 is a sample No. 1 is the same as the coil 2. Sample No. In the coil component 100 of 101, the configuration of the magnetic core 300 is the same as that of the sample No. 1 is different from the coil component 1 of FIG. The specific differences are the following three (a) to (c).

(A) The central leg 320 has a central gap 3220, and the gap length of the central gap 3220 is longer than the outer gap 3120 of the outer leg 310 (gap 312 of the outer leg 31 of sample No. 1). b) Magnitude relation of relative permeability of outer leg 310 and center leg 320 (c) Magnitude relation of cross-sectional area of outer leg 310 and center leg 320

  The magnetic core 300 includes a pair of E cores having the same shape and the same size, and three gaps interposed between three leg pieces (described later) of the pair of E cores. Each E-core includes two outer leg pieces 3110, one central leg piece 3210 disposed therebetween, and a connecting portion 330 that connects the two outer leg pieces 3110 and one central leg piece 3210 in parallel. Is integrally molded. The magnetic core 300 includes a pair of outer leg pieces 3110 arranged in series and two outer leg portions 310 having a gap (outer gap 3120) therebetween, a pair of center leg pieces 3210 arranged in series, and a gap therebetween. And a central leg 320 having a gap (central gap 3220). A winding portion 210 of the coil 200 is disposed on the outer periphery of each outer leg portion 310.

  The cross-sectional areas of the outer leg pieces 3110 in each E core are the same as each other. The cross-sectional area of one outer leg piece 311 is also the same. The outer gap 3120 has a gap length of 0.1 mm, and the central gap 3220 has a gap length of 2.0 m.

  The constituent material of each E core is Sample No. 1 is the same as the outer leg portion 31 and the connecting portion 33, and is composed of a sintered ferrite core. That is, the constituent material of each outer leg piece 3110, each center leg piece 3210, and each connection part 330 is the same. The relative magnetic permeability of each outer leg piece 3110, each center leg piece 3210, and each connection part 330 is the same, and is 3000.

  The cross-sectional area of each central leg piece 3210 is larger than the cross-sectional area of each outer leg piece 3110. The cross-sectional area of each central leg piece 3210 is the cross-sectional area of each outer leg piece 3110 × 1.6 times.

[Evaluation of leakage flux]
Sample No. No. 1 coil part 1 and No. 1 A known simulation capable of expressing the distribution state (magnitude of magnetic flux density) of 101 coil components 100 by color (red, orange, yellow, green, blue, indigo, purple in order of increasing magnetic flux density). Obtained using software. FIG. 7 and FIG. 9 show the distribution state of the magnetic flux density by the simulation, respectively. 7 and 9 are shown in gray scale, there are actually different colors. FIG. 7 shows the distribution state of the magnetic flux density in the cross section cut along the (VII)-(VII) cutting line of the coil component 1 of FIG. FIG. 9 shows a distribution state of magnetic flux density in a cross section taken along the (IX)-(IX) cutting line of the coil component 100 of FIG.

  Sample No. One coil component 1 is red only in the vicinity of the adhesive 4 that bonds the central leg 32 and the pair of connecting portions 33 in the periphery of the magnetic core 3 as shown in FIG. And it turns out that this red range is very small and does not extend to the corner | angular part of the connection part 33. FIG. From this result, it can be seen that the leakage magnetic flux from the central leg 32 can be reduced by the fact that no gap is interposed in the central leg 32.

  On the other hand, sample No. In the coil component 100 of 101, as shown in FIG. 9, the central gap 3220 of the magnetic core 3 and the region extending from the central gap 3220 to the corner of the connecting portion 330 in the periphery of the magnetic core 3 are red. And it turns out that this red range covers a very wide range. From this result, it can be seen that a relatively large gap is interposed in the central leg 320, so that the leakage magnetic flux from the central leg 320 is large.

  The present invention is not limited to these exemplifications, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims. As a coil component used for multi-phase transformer coupling, the above-described first embodiment will be described by taking a coil component used for two-phase transformer coupling as an example, and in the second and third embodiments, three-phase transformer coupling will be described. Although the coil component to be used has been described as an example, it is needless to say that the coil component may be used for four-phase or more transformer coupling. A coil component used for four-phase or more transformer coupling may include four or more coils and one magnetic core. In this case, the magnetic core has the same number of outer legs as the coil. Alternatively, the coil component may include four or more coils and the same number of magnetic cores as the coils. In this case, each magnetic core has two outer legs.

DESCRIPTION OF SYMBOLS 1 Coil component 2 Coil 21 Winding part 22 Pull-out part 3 Magnetic core 31 Outer leg part 311 Outer leg piece 312 Gap 32 Central leg part 33 Connection part 4 Adhesive 5 Circuit board 50 Substrate body 51 Wiring pattern 6 Power supply device 100 Coil part DESCRIPTION OF SYMBOLS 200 Coil 210 Winding part 300 Magnetic core 310 Outer leg part 3110 Outer leg piece 3120 Outer gap 320 Central leg part 3210 Central leg piece 3220 Central gap 330 Connection part

Claims (8)

A coil component used for multiphase transformer coupling,
Comprising a plurality of independent coils and one or more magnetic cores;
The magnetic core is
A plurality of outer legs having a pair of outer leg pieces disposed in series and a gap interposed between the pair of outer leg pieces, wherein at least a part of the coil is disposed;
A central leg having a portion disposed between any two said outer legs, with no gaps interposed therebetween;
A pair of connecting portions for connecting the plurality of outer leg portions and the central leg portion in a parallel state;
The coil component in which the relative permeability of the central leg is smaller than the relative permeability of each outer leg.   The coil component according to claim 1, wherein a cross-sectional area of the central leg portion is smaller than a cross-sectional area of each outer leg portion.   The coil component according to claim 1 or 2, wherein a total of coupling coefficients of an arbitrary coil and the remaining coils among the plurality of coils is 0.7 or more. Each of the connecting portions is formed in series without a gap,
One of the pair of outer leg pieces and one of the pair of connecting portions in each of the outer leg portions are integrally formed,
The other of the pair of outer leg pieces and the other of the pair of connecting portions in each of the outer leg portions are integrally formed,
The coil component according to any one of claims 1 to 3, wherein the central leg portion is a molded body independent of the outer leg portion and the connecting portion. Having one said magnetic core,
The coil component according to any one of claims 1 to 4, wherein the coils are arranged on the outer leg portions. A plurality of the magnetic cores arranged in an annular shape;
Each of the magnetic cores has the two outer legs,
2. The coil collectively stores one outer leg portion of one of the magnetic cores and one outer leg portion of the other magnetic core of the adjacent magnetic cores. The coil component according to claim 1.   A circuit board comprising the coil component according to any one of claims 1 to 6.   A power supply device comprising the circuit board according to claim 7.