JP2013222741A - Reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reactor with an insulation property secured between a conductor wire and a core while having a high inductance.SOLUTION: A reactor 1 comprises: a magnetic core 11 including a first soft magnetic particle and a magnetic core 11; a coil 12 wound around a conductor wire; and an insulator 13 covering a coil surface. The core 12 covered by the insulator 13 is embedded in the magnetic core 11, and the insulator 13 contains plural soft magnetic particles having an insulation property and resin filled in gaps of the soft magnetic particles. A glass transition temperature of the resin is 80°C or more, and the insulator 13 has relative magnetic permeability of 1 or more and 20 or less in a zero magnetic field. The magnetic core 11 has relative magnetic permeability of 3 or more in a magnetic field of 10/4π[A/m].

Description

  The present invention relates to a reactor that is a passive element using a coil.

  As exemplified in Patent Document 1, a configuration of a reactor for boosting is disclosed in which the inside and outside of a coil around which a conductor wire is wound are filled with a magnetic powder mixed resin.

  Patent Document 1 further devises to ensure insulation between the conductor wire and the core obtained by curing the magnetic powder mixed resin by covering the entire coil with an insulator.

  On the other hand, Patent Document 2 discloses a configuration of an inductor in which a coating layer made of Ni—Zn ferrite and a thermoplastic polymer is provided on the surface of an air core coil with a thickness of 300 μm.

JP 2006-4957 A JP-A-6-36937

  In the reactor described in Patent Document 1, the core near the coil contributes to the inductance. However, since the coil surface is covered with an insulator, there is a problem that it is difficult to increase the inductance.

  On the other hand, if the coil in the reactor described in Patent Document 1 is provided with the coating layer described in Patent Document 2, the inductance is improved by the coating layer, but the coating layer contains a thermoplastic resin, so that it is covered by heat generation of the coil. The layer may be softened, and there is a problem that it is difficult to ensure insulation between the conductor wire and the core.

  Accordingly, an object of the present invention is to provide a reactor that has a high inductance while ensuring insulation between a conductor wire and a core.

To solve the above problems, the present invention includes a magnetic core including first soft magnetic particles and a binder, a coil wound with a conductor wire, and an insulator covering the coil surface, and the coil covered with the insulator is magnetic. Embedded in the core, the insulator contains a plurality of second soft magnetic particles having insulating properties and a resin that fills the gaps between the second soft magnetic particles, and the glass transition temperature of the resin is 80 ° C. or higher. The body has a relative permeability greater than 1 and less than 20 in a zero magnetic field, and the magnetic core is solved by a reactor having a relative permeability greater than 3 in a magnetic field of 10 ⁶ / 4π [A / m]. To do.

  The insulator further contains an insulating nonmagnetic powder having a thermal conductivity of 0.5 W / m · K or more, and the volume content of the nonmagnetic powder in the insulator is 5% or more and 60% or less, The volume content of the second soft magnetic particles in the insulator is preferably 10% or more and 55% or less, and the total volume content of the nonmagnetic powder and the second soft magnetic particles in the insulator is preferably 70% or less.

  Further, the insulator has a relative permeability of 2 to 9 in a zero magnetic field, and the relative permeability of the insulator when a current of 200 A or more is passed through the coil is lower than the relative permeability of the magnetic core. A reactor may be used.

  In addition, the thickness of the insulator is desirably greater than 300 μm and not greater than 6.0 mm.

  The second soft magnetic particles in the insulator are particles having D50 of 1 μm or more and 300 μm or less, and it is desirable that the second soft magnetic particles have a gap inside. The gaps in the second soft magnetic particles may be pores or may be filled with a resin or the like.

  Note that D50 is a volume-based cumulative frequency equivalent to 50%.

  According to the present invention, it is possible to provide a reactor in which insulation between a conductor wire and a core is ensured while having high inductance.

It is a perspective view which shows the 1st example of the reactor in this invention. It is sectional drawing of the AA surface in FIG. 1 which shows the 1st example of the reactor in this invention. It is an expanded sectional view of field AB in Drawing 2 showing the 1st example of the reactor in the present invention. It is an expanded sectional view of area | region CD in FIG. 2 which shows the 1st example of the reactor in this invention. It is an expanded sectional view of area | region CD in FIG. 2, which shows the 2nd example of the reactor in this invention. It is an expanded sectional view of area | region CD in FIG. 2, which shows the 3rd example of the reactor in this invention. It is a figure which shows the direct current | flow superimposition inductance with respect to the relative permeability (micro | micron | mu) of an insulator.

The present invention includes a magnetic core including first soft magnetic particles and a binder, a coil wound with a conductor wire, and an insulator that covers the coil surface, and the coil covered with the insulator is disposed in the magnetic core. Embedded, the insulator contains insulating second soft magnetic particles and resin, the resin has a glass transition temperature of 80 ° C. or higher, and the insulator has a relative permeability of greater than 1 and less than 20 in a zero magnetic field. And the magnetic core can take an embodiment as a reactor having a relative permeability of 3 or more in a magnetic field of 10 ⁶ / 4π [A / m]. The relative permeability of the magnetic core in a magnetic field of 10 ⁶ / 4π [A / m] is more preferably 4 or more. The relative permeability of the magnetic core in a zero magnetic field is preferably 7 or more and 30 or less, and more preferably 10 or more and 20 or less.

By using a resin having a glass transition temperature of 80 ° C. or higher for the insulator, a large current that generates a magnetic field of about 10 ⁶ / 4π [A / m] in the magnetic core when using a reactor, that is, 200 A or higher Even if the current is applied to the coil and heat is generated from the coil, softening of the insulator is suppressed, so that the relative permeability of the insulator has high inductance, but the conductor wire and the core Insulating properties can be ensured.

  The glass transition temperature of the resin in the insulator covering the coil surface is preferably 80 ° C. or higher, more preferably 120 ° C. or higher, and further preferably 150 ° C. or higher.

  The insulator preferably has a relative permeability of more than 1 and 20 or less, and more preferably 2 or more and 9 or less, by adjusting the volume ratio of the second soft magnetic particles in the entire insulator. Magnetic saturation caused by a strong magnetic field induced in the vicinity of the coil is formed by dispersing the second soft magnetic particles so as to have a uniform magnetic gap in the insulator and configuring the insulator so that the relative permeability is 20 or less. Can be prevented.

  Note that the reactor according to the present invention has an inductance when a direct current of 200 A is superimposed on L: 200 A, and an inductance when a direct current is not superimposed on L: 0 A, L: 200 A is 50% of L: 0A. The above is desirable.

  The insulator further contains an insulating nonmagnetic powder having a thermal conductivity of 0.5 W / m · K or more, and the volume content of the nonmagnetic powder in the insulator is 5% or more and 60% or less, The volume content of the second soft magnetic particles in the insulator is preferably 10% or more and 55% or less, and the total volume content of the nonmagnetic powder and the second soft magnetic particles in the insulator is preferably 70% or less.

  By including non-magnetic powder with high thermal conductivity in the insulator, the thermal conductivity from the coil to the magnetic core can be enhanced. By making the total volume content of the non-magnetic powder and the second soft magnetic particles 70% or less, the volume content of a liquid such as a resin in the uncured insulator becomes 30% or more. Sufficient fluidity can be obtained in performing the operation of forming a cured insulator.

The nonmagnetic powder contained in the insulator includes silicon oxide (SiO ₂ ) powder having a thermal conductivity of about 0.8 W / m · K, and alumina (Al ₂ having a thermal conductivity of about 40 W / m · K). O ₃₎ but is exemplified by, but not limited thereto. The thermal conductivity of the nonmagnetic powder is more preferably 30 W / m · K or more.

  In addition, the present invention further has a relative permeability of 2 to 9 in a zero magnetic field, and the relative permeability of the insulator when a current of 200 A or more is passed through the coil is the ratio of the magnetic core. The embodiment as a reactor lower than the magnetic permeability can be taken.

  Since the magnetic field induced by energizing the coil is stronger as it gets closer to the coil, a magnetic field larger than that of the magnetic core is applied to the insulator provided on the coil surface. Therefore, the magnetic saturation of the insulator can be prevented by making the relative permeability of the insulator lower than the relative permeability of the magnetic core when the coil is energized.

  The thickness of the insulator is desirably greater than 0.3 mm and not greater than 6.0 mm, and more desirably not less than 1.5 mm and not greater than 6.0 mm. In order to insulate the magnetic core from the induced electromotive force generated in the coil due to the inductance, it is desirable that the thickness of the insulator is greater than 0.3 mm. The following is desirable.

  The second soft magnetic particles in the insulator are particles having D50 of 1 μm or more and 300 μm or less, and it is desirable that the second soft magnetic particles have a gap inside.

  The D50 of the second soft magnetic particles is desirably 1 μm or more in order to ensure sufficient fluidity for coating the coil surface, and desirably 300 μm or less due to the restriction on the insulator thickness.

  The insulator is required to have a sufficiently low relative magnetic permeability to prevent magnetic saturation. At the same time, in order to prevent magnetic saturation of the second soft magnetic particles themselves, it is desirable that the second soft magnetic particles have a gap inside.

  Moreover, if there is a gap connected to the surface inside the second soft magnetic particles, the contact area when mixed with an uncured resin is increased. Moreover, since the 2nd soft magnetic particle will become light if the clearance gap inside a 2nd soft magnetic particle contains gas, it will approach specific gravity of resin. Therefore, since the familiarity with the uncured resin is improved by having a gap connected to the surface inside the second soft magnetic particle, it is easy to mix with the resin.

  The gap inside the second soft magnetic particles may be a pore, that is, a gap filled with gas, or at least a part of the gap may be filled with resin or the like.

  The volume ratio of the gaps in the second soft magnetic particles is preferably 3% or more, more preferably 5% or more, and even more preferably 10% or more.

  The second soft magnetic particles having a gap in the inside thereof are prepared, for example, by sufficiently mixing Ni—Zn-based ferrite material powder, adding an organic binder such as polyvinyl alcohol, granulating, and firing. be able to.

  The Ni-Zn ferrite powder described in Patent Document 2 is produced by crushing after sintering, but if it is produced by the above method, the crushing step, the forming step, and the sintering step are not necessary. It can be manufactured at low cost.

  In order to prevent magnetic saturation, the saturation magnetization of the insulator is preferably larger than 0.05 Tesla.

  Further, when a ferrite material is used as the second soft magnetic particles, the saturation magnetization of the sintered body having the same composition as that of the second soft magnetic particles is desirably 0.2 tesla or more.

(Embodiment 1)
An example of an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view showing a first example of a reactor in the present invention.

  The reactor 1 in this invention can be used by supplying with electricity to the terminals 21 and 22 derived | led-out from the both ends of the coil mentioned later. The reactor in the present invention is suitable as a reactor for a booster circuit because a sufficient inductance can be maintained even when a large current of 200 A or more is applied.

  2 is a cross-sectional view of the AA plane in FIG. 1 showing a first example of a reactor in the present invention.

  A coil 12 is embedded in the magnetic core 11, and an insulator 13 is provided between the magnetic core 11 and the coil 12. Since the insulator 13 covers the surface of the coil 12, the insulation between the magnetic core 11 and the coil 12 is maintained by the insulator 13.

  The coil 12 may be a coil wound with a round wire having an insulating film, or may be a coil formed by edgewise winding a flat wire having an insulating film, such as aluminum or copper. A foil wound coil in which the conductive foil and the insulating sheet are alternately wound may be used.

  3 is an enlarged cross-sectional view of a region AB in FIG. 2 showing a first example of a reactor in the present invention.

  The coil 12 is embedded in a magnetic core including the binder 111 and the first soft magnetic particles 112, and the surface of the coil 12 is covered with an insulator containing the resin 131 and the particulate second soft magnetic particles 132. ing.

  As the first soft magnetic particles 112, for example, Fe—Si based metal magnetic particles containing 6.5 mass% Si are desirable. However, it may be a metal magnetic particle such as pure iron or amorphous, and is not limited to this as long as it is a soft magnetic particle having a high saturation magnetization.

  Examples of the particulate second soft magnetic particles 132 include Ni—Zn-based ferrite powder which is a soft magnetic material having insulating properties. In particular, Ni—Zn ferrite powder is desirable by firing the granulated powder as it is, but is not limited thereto.

  The resin 131 is a resin having a glass transition temperature of 80 ° C. or higher, and is preferably a thermosetting resin that does not undergo plastic deformation even in a high temperature environment of 80 ° C. or higher. As a thermosetting resin, it can select from an epoxy resin, a phenol resin, a melamine resin, etc. suitably, for example.

  By energizing the coil 12, a magnetic field is applied to the inside of the magnetic core and the insulator. In particular, in the boosting application, the energization current to the coil may exceed 200A.

In such a boosting application, the magnetic field H applied to the inside of the magnetic core often reaches a strong magnetic field of 10 ⁶ / 4π [A / m].

  By adjusting the blending ratio and particle size of the first soft magnetic particles 112 in the magnetic core including the binder 111 and the first soft magnetic particles 112, a relative magnetic permeability of 3 or more can be obtained without saturation even in such a strong magnetic field. Can keep.

  On the other hand, since the insulator is closer to the coil than the magnetic core, the magnetic field H ′ applied to the inside of the insulator is stronger than the magnetic field H applied to the inside of the magnetic core.

  Therefore, by setting the relative permeability in the zero magnetic field of the insulator to be greater than 1 and 20 or less, magnetic saturation of the insulator can be prevented even under such a strong magnetic field, and the coil is energized. The inductance of the reactor can be improved.

  4 is an enlarged cross-sectional view of a region CD in FIG. 2 showing a first example of a reactor in the present invention.

  The entire surface of the coil 12 embedded in the magnetic core 11 is covered with an insulator containing the resin 131 and the second soft magnetic particles 132.

  For example, when a thermosetting resin is used, the coil surface can be coated with an insulator by applying a mixture containing uncured resin 131 and second soft magnetic particles 132 to the coil surface and thermally curing the mixture. Become.

(Embodiment 2)
FIG. 5 is an enlarged cross-sectional view of a region CD in FIG. 2 showing a second example of the reactor in the present invention. That is, FIG. 5 shows a modification of FIG.

  The coil 12 is accommodated in a case 133, and the case 133 is filled with an insulator including a resin 131 and particulate second soft magnetic particles 132 to a height that completely covers the coil 12.

  Filling the insulator can be performed by pouring an uncured insulator into the case 133.

  In order to allow an uncured insulator to flow between the coil 12 and the case 133 and to fill the gap without any gap, the gap between the coil 12 and the case 133 is preferably 1.0 mm or more, and 1.5 mm. More preferably.

  The case 133 may contain only the insulating resin or may further contain the second soft magnetic particles, but the glass transition temperature is desirably 80 ° C. or higher, and the insulating resin to be applied A higher glass transition temperature is more desirable because it can more reliably prevent the coil from being softened due to heat generation.

  In addition, since no insulator is provided between the end surface of the coil 12 in the winding axis direction and the bottom of the inner surface of the case 133, the thickness of the bottom of the case 133 is made thicker than other portions in order to ensure insulation. May be.

(Embodiment 3)
FIG. 6 is an enlarged cross-sectional view of a region CD in FIG. 2 showing a third example of the reactor in the present invention. That is, FIG. 6 shows a modification of FIG.

  A resin spacer 1311 is bonded to the case 133 or integrally molded, and the coil 12 and an uncured insulator are poured into the case 133 to form insulators 1321 and 1322. At this time, a gap is provided between the resin spacer 1311 and the coil 12 or a part of the resin spacer 1311 so that an uncured insulator can be filled in the case.

  Here, the coil 12 may be put into the case 133 first and the uncured insulator may be poured therein. Conversely, the uncured insulator may be poured into the case 133 and the coil 12 may be inserted.

  FIG. 7 is a diagram showing the DC superimposed inductance with respect to the relative permeability μ of the insulator. That is, the inductance L (0A) when the DC current is not superimposed and the inductance L (200A) when the DC current is superimposed by 200A with respect to the relative permeability μ of the insulator 13 in the configuration of the first embodiment are shown. FIG.

  The inductance L: 0A increases uniformly with respect to the relative permeability μ of the insulator 13. On the other hand, the inductance L: 200A is the maximum when the relative permeability μ of the insulator 13 is 5.

  Further, the insulation L: 200A, which indicates that the insulator 13 is a non-magnetic material and the relative permeability μ = 1 of the insulator 13, is the reference value, and the inductance L: 200A is more than half of the maximum value. The range of the relative permeability of the body 13 is 2 or more and 9 or less.

  From the result of FIG. 8, it was found that the desirable range of the relative permeability of the insulator 13 is 2 or more and 9 or less.

  However, when 200 A or more is assumed as the superimposed current, if the relative magnetic permeability of the insulator 13 is larger than 5, the inductance may be greatly reduced by the superimposed current.

  Therefore, in order to prevent magnetic saturation due to the superimposed current, the relative magnetic permeability of the insulator 13 is preferably 2 or more and 7 or less, and more preferably 2 or more and 5 or less.

1 Reactor
11 Magnetic core
111 binder
112 First soft magnetic particles
12 coils
13, 1321, 1322 Insulator
1311 Resin spacer
132 Second soft magnetic particles
133 cases
21 and 22 terminals
H, H 'magnetic field

Claims (5)

A magnetic core comprising first soft magnetic particles and a binder;
A coil wound with a conductor wire;
Comprising an insulator covering the coil surface;
The coil covered with the insulator is embedded in the magnetic core;
The insulator contains a plurality of second soft magnetic particles having insulating properties and a resin filling a gap between the second soft magnetic particles,
The glass transition temperature of the resin is 80 ° C. or higher,
The insulator has a relative permeability greater than 1 and less than or equal to 20 in a zero magnetic field;
The magnetic core has a relative magnetic permeability of 3 or more in a magnetic field of 10 ⁶ / 4π [A / m]. The insulator further includes an insulating nonmagnetic powder having a thermal conductivity of 0.5 W / m · K or more,
The volume content of the nonmagnetic powder in the insulator is 5% or more and 60% or less,
The volume content of the second soft magnetic particles in the insulator is 10% or more and 55% or less,
The reactor according to claim 1, wherein the total volume content of the nonmagnetic powder and the second soft magnetic particles in the insulator is 70% or less. The insulator has a relative permeability of 2 or more and 9 or less in a zero magnetic field,
A relative permeability of the insulator when a current of 200 A or more is passed through the coil is lower than a relative permeability of the magnetic core.
The reactor according to claim 1 or claim 2.   The reactor according to any one of claims 1 to 3, wherein a thickness of the insulator is greater than 0.3 mm and equal to or less than 6.0 mm. The second soft magnetic particles in the insulator are particles having a D50 of 1 μm or more and 300 μm or less,
The reactor according to any one of claims 1 to 4, wherein the second soft magnetic particles have a gap inside.

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