JP2011238671A - Composite magnetic element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite magnetic element improved in copper loss, core loss, heat stress and noise.SOLUTION: A composite magnetic element 4 consists of a coil composed of conductor bundles 21, 22 and a conductor 3 which electrically connects the conductor bundles, and a composite magnetic body 1 in which the conductor bundles 21, 22 and the conductor 3 are arranged. The coil consists of the conductor bundles 21, 22, and the conductor 3 is derived from the end of the conductor bundle 21 and introduced as the end of the conductor bundle 22. That is, the conductor 3 is exposed between the conductor bundle 21 and the conductor bundle 22 by coiling the conductor into the conductor bundle 21, making space and then coiling the conductor into the conductor bundle 22, without cutting the conductor.

Description

  The present invention relates to a composite magnetic element such as a reactor, which is mainly used in a power supply circuit such as an inverter and used by energizing a large current.

  Patent Document 1 discloses a configuration of an inductor in which a coil with an insulating coating is formed so as to be wrapped with a mixture of magnetic powder and a binder, and an external electrode is connected to the coil. Moreover, the structure of the inductor shape | molded so that it may wrap with the composite magnetic body 1 which is a mixture of magnetic powder and a binder as shown in FIG. .

  In Patent Document 2, the concentration of magnetic flux inside the butt corner portion of the core is measured on the end face where the cores face each other. A configuration is disclosed. The inclined notch passes through the coil by providing the gap G in the direction along the loop-shaped magnetic flux path formed in the core so that the length on the inner side is larger than the outer side of the magnetic flux path. Elimination of leakage magnetic flux.

Japanese Patent Application Laid-Open No. 5-291046 JP 2006-351959 A

  In the inductor shown in FIG. 11 disclosed in Patent Document 1 that is wound so that the conductive wires 2 are adjacent to each other, there is a magnetic flux B that goes around one conductive wire and enters the adjacent conductive wire, and the magnetic flux B changes over time. In this case, copper loss occurs due to eddy currents generated in adjacent conductors. In addition, the magnetic field H that circulates around the coil that is an assembly of the conducting wires 2 is a combination of the magnetic fields of all the conducting wires 2, so that a magnetic flux generated by the magnetic field H when a large current is passed through the conducting wires 2. The density B tends to concentrate on the magnetic material near the surface of the winding, and magnetic saturation is likely to occur.

  Moreover, in the structure of patent document 2, since the magnetic gap is provided between cores, magnetic flux density is non-uniform | heterogenous compared with the inductor of patent document 1. FIG. If the magnetic flux density is not uniform, the core loss increases because the core loss is proportional to the square of the magnetic flux density.

  The present invention has been made to solve the above-described problems of the prior art, and its purpose is to improve copper loss, eddy current loss, core loss, high power conversion efficiency, high energy saving effect, and even high current. An object of the present invention is to provide a composite magnetic element that can withstand applications.

  The present invention has the above-mentioned problem, comprising a composite magnetic body comprising soft magnetic powder and a binder, and a winding made of a spiral conductive wire, the winding being embedded in the composite magnetic body, and at least of the composite magnetic body This is solved by a composite magnetic element characterized in that a part is arranged between the conductive wires.

  The conductive wire is a linear conductor, and it is desirable to ensure insulation by forming an insulating coating on the surface.

  Since the magnetic flux flows into the composite magnetic body disposed between the conductive wires, it is possible to prevent the magnetic flux from entering the adjacent conductive wires, so that the eddy current loss of the adjacent conductive wires is improved.

  Furthermore, the composite magnetic body disposed between the conductive wires serves as a heat sink, and excessive heat generation of the conductive wires due to energization can be prevented. Further, in the conventional configuration shown in FIG. 11, the thermal expansion of the conductive wire caused by the heat generated by energization occurs around one winding, and depending on the conditions, a large thermal stress is exerted on the composite magnetic body, Although there is a concern about the occurrence of cracks, according to the present invention, a composite magnetic body serving as a heat sink is arranged around the conducting wire serving as a heat generation source, and further, magnetic flux is dispersed inside the composite magnetic body, thereby generating heat due to core loss. Therefore, cracks due to thermal stress can be prevented in advance.

  Further, since the magnetic flux is distributed to the composite magnetic body disposed between the conductive wires, the magnetic flux density becomes uniform, so that saturation of the magnetic flux B can be prevented and core loss can be improved at the same time. Further, in the conventional configuration shown in FIG. 11, the magnetic attraction generated inside the composite magnetic body is a large force due to the magnetic flux concentrated around one winding, whereas in the configuration of the present invention, the magnetic flux Since the generation sites are dispersed, the vibration and noise of the element due to the electromagnetic attractive force can be dispersed and reduced. In addition, the vibration and noise of the element due to the Lorentz force generated between the windings are also reduced by the composite magnetic body disposed between the windings.

  Furthermore, the present invention solves the above problem by a composite magnetic element in which a winding is composed of a plurality of conductor bundles and a composite magnetic body is disposed between the conductor bundles. Although it is desirable to use an insulating film formed on the surface of these conductors, an insulating layer may be further formed on the surface of the conductor bundle to further enhance the insulation.

  The effect of the present invention can be obtained even in a configuration in which a composite magnetic body is arranged between each conductor. However, since the conductor wire is bundled into a conductor bundle, a gap between the conductor bundles can be greatly increased. The workability at the time of filling in is improved.

  Furthermore, this invention solves the said subject by comprising so that the cross section of the conducting wire which mutually adjoins in a conducting wire bundle may be continued in a bead shape.

  By arranging the cross sections of the conductive wires so as to be continuous in a bead shape, all the conductive wires are in contact with the composite magnetic body, so that the penetration of magnetic flux into the adjacent conductive wires can be more reliably prevented.

  In particular, it is possible with existing equipment to make a cross section of the conducting wire beaded along a straight line parallel to the winding axis, that is, to create a solenoid coil, and the workability during winding is also good.

  Furthermore, this invention solves the said subject by comprising so that the cross-sectional area of the conducting wire in an inside conducting wire bundle may differ from the cross-sectional area of the conducting wire in an outside conducting wire bundle.

  Heat generated by the copper loss of the conductive wire and the core loss of the composite magnetic material is radiated from the surface of the composite magnetic element, and in particular, it is necessary to suppress the heat generation inside the composite magnetic element as much as possible to promote heat dissipation. Therefore, if the cross-sectional area of the conductor in the inner conductor bundle is made larger than the cross-sectional area of the conductor in the outer conductor bundle, the heat resistance due to copper loss is suppressed because the electrical resistance of the inner conductor bundle is low. Heat is transferred from the large inner conductor to the outer conductor, and is radiated from the outer conductor and the composite magnetic body.

  Furthermore, this invention solves the said subject because the cross section of conducting wire is made into a circle.

  The so-called round wire, in which the cross section of the conducting wire is a circle, can minimize the contact area between adjacent conducting wires as compared to a so-called rectangular wire having a square cross section. The eddy current loss is also improved by preventing the magnetic flux from entering adjacent conductors to a minimum by being filled. At the same time, the composite magnetic body serves as a heat sink, and the heat dissipation effect can be enhanced. Further, the round wire does not cause kinking during winding that occurs in a flat wire.

  According to the present invention, it is possible to provide a composite magnetic element with improved copper loss, eddy current loss, and core loss, high power conversion efficiency, and high energy saving effect.

  In addition, since it is difficult to saturate magnetically, there is little decrease in inductance with respect to the energized current, so-called DC superposition characteristics are excellent, and heat dissipation is also excellent, so it can withstand applications such as inverters that energize large currents. A composite magnetic element can be provided.

It is a top view of the composite magnetic element in the embodiment of the present invention. It is a side view of the composite magnetic element in embodiment of this invention. FIG. 2 is a cross-sectional view of the AA plane in FIG. 1 according to the embodiment of the present invention. It is a top view of the composite magnetic element in other embodiment of this invention. FIG. 5 is a cross-sectional view of the AA plane in FIG. 4 according to another embodiment of the present invention. FIG. 5 is a cross-sectional view of the AA plane in FIG. 4 according to another embodiment of the present invention. FIG. 5 is a cross-sectional view of the AA plane in FIG. 4 according to another embodiment of the present invention. It is a top view of the composite magnetic element in other embodiment of this invention. FIG. 9 is a cross-sectional view of the AA plane in FIG. 8 according to another embodiment of the present invention. It is explanatory drawing of the magnetic flux B around the conducting wire in this invention. It is sectional drawing of the composite magnetic body in a prior art.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  An example of the composite magnetic element in the present invention is shown in FIGS. The composite magnetic element 4 is composed of a winding composed of the conductor bundles 21 and 22 and the conductor 3 that electrically connects the conductor bundles, and the composite magnetic body 1 in which the conductor bundles 21 and 22 and the conductor 3 are embedded. .

  The winding consists of conductor bundles 21 and 22, and the conductor 3 is led out from the end of the conductor bundle 21 and introduced from the end of the conductor bundle 22. That is, after winding the conducting wire bundle 21, the conducting wire 3 is exposed between the conducting wire bundle 21 and the conducting wire bundle 22 by winding the conducting wire bundle 22 at intervals without cutting the conducting wire. Of course, the two conductor bundles may be manufactured separately, and the terminal portions of the conductors in each conductor bundle may be connected outside the composite magnetic element 4. In any case, it is desirable that the directions of the currents flowing through the two wire bundles are the same.

  As the composite magnetic body 1, for example, a metal magnetic powder and a thermosetting liquid resin mixed to form a slurry can be used. The thermosetting resin preferably has a low viscosity so as to have sufficient fluidity when made into a slurry. For example, an epoxy resin can be used. Here, dust powder such as gas atomized powder of Fe-Si 6.5% material can be used as the magnetic powder. When these are mixed with a resin to form a slurry, alumina powder, silica powder, or the like may be blended at the same time to reduce the space factor of the dust powder, which is a magnetic material, and adjust the magnetic permeability. The composite magnetic element 4 can be obtained by casting the magnetic slurry blended according to the above procedure into a mold in which windings made of the conductor bundles 21 and 22 and the conductor 3 are set and heat-curing. Of course, a composite magnetic body having a shape that can be a winding core is formed in advance, and after winding this, it is set in a mold and cast into the space portion with a slurry of the composite magnetic body. good.

  The composite magnetic element 4 is preferably used with an energization current in the range of, for example, 50 A or more and 700 A or less. In that case, in order to prevent magnetic saturation of the composite magnetic material, the relative permeability is preferably set to 500 or less. On the other hand, by setting the relative permeability low, the magnetic flux cannot circulate around the entire winding and easily enters the conductor, but as shown in FIG. 3, it circulates the cross section of the conductor bundle in the present invention. Since the magnetic flux B flows between the conductor bundles 21 and 22, it is possible to prevent the magnetic flux B from entering the conductor 3. In addition, as the conducting wire 3, for example, a round copper wire having a diameter of about 3 mm can be used.

  Moreover, the structure of FIG.4, FIG.5, FIG.6, FIG.7 made into what is called a solenoid coil shape where the cross section of the conducting wire which adjoins each other in a conducting wire bundle continued in a bead shape may be sufficient.

  The conducting wires in the conducting wire bundle have a low required inductance, and when used for an application in which a large current is passed, an interval is provided between adjacent conducting wires as shown in FIG.

  Further, when the inductance required is relatively high and the energization current is relatively small, as shown in FIG.

  Further, as shown in FIG. 7, by making the cross-sectional area of the conductor in the inner conductor bundle 21 larger than the sectional area of the conductor in the outer conductor bundle 22, the electrical resistance of the inner conductor bundle 21 is low. This is desirable because heat generation due to is suppressed, and heat is transferred from the inner conductor 21 having a large cross-sectional area to the outer conductor 22 and radiated from the outer conductor 22 and the composite magnetic body 1. In addition, when the composite magnetic body in the vicinity of the center of the winding axis in FIG. 7 is replaced with a member having high thermal conductivity such as aluminum and the internal cooling performance is enhanced, the cross sectional area of the conductor in the inner conductor bundle is conversely changed. It may be small.

  Moreover, since the conducting wire 3 which connects the inner side conducting wire 21 and the outer side conducting wire 22 is made into a planar shape parallel to the magnetic flux, heat transfer from the inner conducting wire 21 to the outer conducting wire 22 is promoted. Of course, the two conductor bundles may be manufactured separately and the terminal portion may be connected outside the magnetic element. In any case, it is desirable that the directions of the currents flowing through the two wire bundles are the same.

  Furthermore, it is good also as a structure which the cross section of the conducting wire 2 mutually follows an annular | circular shape like FIG. 8, FIG. A magnetic element can be formed by previously providing a gap in a part of the conductive wire 2 and casting the slurry. In this case, the magnetic flux B inside the conductor 2 and the magnetic flux B outside are opposite to each other.

  Moreover, as for the conducting wire 2, it is desirable for a cross section to be a circle. If the cross section is a so-called round wire, the contact area between the adjacent conductors can be minimized by filling the composite magnetic body between the conductors as shown in FIG. Since the composite magnetic material fills the gaps between the conductors, the composite magnetic material acts as a heat sink and provides heat dissipation, but at the same time, eddy current loss is prevented by minimizing the penetration of magnetic flux into the adjacent conductors. Can be suppressed.

  In the magnetic element to which the present invention is applied, the direct current loss and the alternating current loss of the winding are about 50%, and the iron loss is about 50%. The efficiency of the inverter operation is reduced by reducing both of these losses. The loss reduction effect of the present invention can also be enjoyed from the viewpoint of environmental measures such as fuel efficiency and energy saving.

  In addition, the AC loss of the winding is due to the skin loss that makes it easy for current to flow on the surface of a single wire cross section and the proximity loss due to the generation of eddy current when the magnetic field generated by the nearby strand penetrates the winding. However, it is easy to separate them, and when measuring the AC resistance of the wound winding, the total loss of both can be obtained. Only skin damage is measured. For example, at 10 kHz, the skin loss is 10%, the proximity loss is 90%, and the influence of the proximity loss is large. Thus, the proximity loss having a great influence can be reduced by the present invention.

DESCRIPTION OF SYMBOLS 1 Composite magnetic body 2, 3 Conductor 21, 22 Conductor bundle 4 Composite magnetic element B Magnetic flux

Claims (6)

  A composite magnetic body comprising soft magnetic powder and a binder, and a winding made of a helical conductor, the winding being embedded in the composite magnetic body, and at least a part of the composite magnetic body between the conductors A composite magnetic element characterized by being arranged in   The composite magnetic element according to claim 1, wherein the winding includes a plurality of conductor bundles, and the composite magnetic body is disposed between the conductor bundles.   3. The composite magnetic element according to claim 2, wherein sections of the conducting wires adjacent to each other in the conducting wire bundle are arranged in a beaded manner.   4. The composite magnetic element according to claim 3, wherein sections of the conducting wires adjacent to each other in the conducting wire bundle are arranged in a beaded manner along a straight line parallel to a winding axis of the winding.   5. The composite magnetic element according to claim 4, wherein a cross-sectional area of the conductor in the inner wire bundle in the winding is different from a cross-sectional area of the conductor in the outer conductor bundle.   6. The composite magnetic element according to claim 1, wherein a cross section of the conducting wire is a circle.

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