1. Field of the Invention
The present invention relates to an inductive component. More particularly, the present invention provides an inductive component with a magnetic circuit made of a magnetically soft core material and a coil wound about a part of the core material are well known throughout the electrical engineering industry. The magnetic circuit frequently also has a gap that extends from a first free end on the front of the core material to a second free end on the front of the core material on the opposite side.
2. Description of the Related Art
Such inductive components are used as voltage regulators in the form of so-called buck converters or step-up converters, for example. One example for a so-called step-up converter is disclosed in the introductory part of the specification of DE 198 16 485 A and the
This DE 198 16 485 A1 furthermore discloses biasing the inductive component magnetically negative, by filling the mentioned gap with permanent magnetic material, opposite to the field of winding. Because of this, it is possible to shift the actual operating range of the inductive component, because the maximum possible magnetic deviation, i.e. the maximum change, i.e. the maximum change in magnetic induction, is significantly increased by providing the permanent magnetic material in the gap.
If such permanent magnets are inserted in the gap of the magnetic circuit of the inductive component, however, undesirable eddy currents develop as soon as the inductive component conducts high-frequency a.c. components. The higher the frequency of the alternating magnetic field and the higher the energy of the alternating field, the larger the eddy currents will be.
This problem was identified in DE 2 424 131 A1, and it was proposed to subdivide the permanent magnet into a plurality of individual permanent magnet elements in order to reduce the eddy current losses. In a specific embodiment, a total of 25 individual permanent magnet elements were actually proposed, each of which are disposed as identical cubes in a 5×5 matrix within the gap (refer to
The provision and in particular the alignment and the configuration of these individual permanent magnet elements in the gap creates problems, as is addressed in DE 2 424 131 A1 itself, because if these individual magnet elements are disposed in close proximity to each other, a repulsion between the magnet elements having the same polarity occurs when aligning the magnetizing directions of the individual permanent magnet elements. The individual magnetic pieces can therefore not be configured aligned, unless in this process sufficient spaces are maintained between adjacent individual permanent magnet elements. For that reason, it is proposed to glue the individual permanent magnet elements onto one of the end faces of the magnetic circuit facing the gap and then place the two-part magnetic circuit with the second front end onto the other side of the individual permanent magnet elements.
In addition, further assembly options are presented for the individual permanent magnet elements. Moreover it is proposed to glue the individual permanent magnet elements initially onto a film, for example, and then introduce these individual permanent magnet elements together with the film into the gap. Ultimately it is also discussed to install a multiplicity of recesses on the two opposite end faces of the free front ends of the magnetic circuit, into which the individual permanent magnet elements can be individually inserted in each case.
The assembly of these individual permanent magnet elements in the magnetic circuit and their fixation in situ is therefore problematic and more complex, even though the use of individual permanent magnet elements significantly reduces the eddy current losses of the inductive component.
Another problem when using a multiplicity of individual permanent magnet elements, in particular rectangular or cubic magnet elements, is the fact that the so-called fill factor becomes increasingly unfavorable, i.e. worse, because of the necessary spacing between the magnet elements. The fill factor stands for the ratio of the magnetically effective cross-section to the geometric cross-section.
The present invention is based on these findings.
Accordingly, there is a need for an improved inductive component that addresses at least one of the concerns noted above.
According to one aspect of the invention there is provided an inductive component with a magnetic circuit is made of a magnetically soft core material, the magnetic circuit having at least one gap which extends in the Y direction from a first end-side free end of the core material to an opposite second end-side end of the core material, at least one coil which is wound around at least one part of the core material, and a permanent magnet unit which consists of multiple mutually spaced individual permanent magnetic elements, each of which has a magnetizing direction, the directions being oriented in an at least approximately identical manner to the Y direction The individual permanent magnets are stacked next to one another in a mutually spaced manner primarily in a direction which is at least approximately orthogonal to the Y direction. There is high magnetic biasing of the inductor by means of the permanent magnets, little power loss, a simple production, and a high fill factor.
One alternative aspect of the present invention is to develop the known inductance with inserted permanent magnets for magnetic biasing such that eddy current losses are kept low during operation on the one hand, and on the other that the manufacturing process will also be as uncomplicated as possible.
This aspect is solved by an inductive component with the features pursuant to the enclosure herein.
The inductive component according to the present invention is essentially based upon the fact that the individual permanent magnet elements are primarily stacked next to one another, and in a particular embodiment of the present invention are exclusively stacked next to one another in one direction, wherein the one direction is at least almost orthogonal to the Y-direction, i.e. in that direction which is given by the longitudinal extension of the gap in the magnetic circuit, which extends in the Y-direction from the first end-side free end of the core material to an opposite second end-side of the core material.
In a preferred embodiment of the present invention, it is provided that the individual permanent magnet elements are laminated, i.e. as lamellae or strips, the individual lamellae or strips being disposed reciprocally spaced apart in one direction.
Even though in principle it is possible that a thin air layer is provided as an insulator between the individual permanent magnet elements, there is also the option to use any other insulation material, for example a plastic film, a paper layer, an adhesive coating, or suchlike.
In another development of the present invention, it is provided that the height of the individual permanent magnet elements is larger in the Y-direction, i.e. in the longitudinal extension of the gap, than the width of the individual permanent magnet elements in stack direction. This width can be in the order of magnitude of 1 mm, for example.
It is also within the scope of the present invention that the inductive component has a further gap, in particular an air gap, which is provided in the magnetic circuit. This air gap can be provided as a separate gap next to the gap in which the permanent magnet unit is placed in the magnetic circuit. However, it is also possible that this further gap is a constituent of the one gap in which the permanent magnet unit rests. This means that the permanent magnet unit is spaced apart for example either from one or from both front faces of the core material consisting of magnetically soft material.
In one alternative embodiment of the present invention, the individual permanent magnet elements can be configured being stacked on top of one another in the gap direction.
There is the option of using a combination of rare earths as magnetic material of the individual permanent magnet pieces, for example SmCo, NdFeB, SmFeN or a hard ferrite, in particular SrFe, BaFe or a mixture of these materials. These first-mentioned magnetic materials are characterized by an exceptionally high residual flux density and a high magnetic coercitive field strength and thus by a high magnetic energy density.
Although the individual permanent magnet elements are formed as lamellae or strips situated side-by-side in a particular embodiment of the present invention, it is also within the scope of the present invention that the individual permanent magnet elements are reciprocally curved, in particular angled. It is moreover also possible that the individual permanent magnet elements are disposed reciprocally coaxial, or that the permanent magnetic unit is realized coaxially wound.
The permanent magnet unit can be particularly easily handled, if it is formed as comb structure, that is that the plurality of individual permanent magnet pieces are mechanically connected to one another as one piece or multi-piece in the form of lamellae or strips on one end or on one end face. Although as an option, the connection of the individual permanent magnet elements can also be provided at different positions within the permanent magnet unit, so that also a double comb structure with a connecting middle piece or a zigzag structure or still even other structures are possible for the permanent magnet unit.
The above and other aspects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.
a-2f show six possible embodiments of a permanent magnet unit as it can be used in
a-3c are plan views of three further embodiments of permanent magnet units, as they can be inserted in
a-6c are plan views of three different permanent magnet units, i.e. one with a single block, one with four individual permanent magnet elements and one with 16 individual permanent magnet elements.
Reference will now be made in detail to embodiments of the invention. Wherever possible, same or similar reference numerals are used in the drawings and the description to refer to the same or like parts or steps. The drawings are in simplified form and are not to precise scale. The word ‘couple’ and similar terms do not necessarily denote direct and immediate connections, but also include connections through intermediate elements or devices. For purposes of convenience and clarity only, directional (up/down, etc.) or motional (forward/back, etc.) terms may be used with respect to the drawings. These and similar directional terms should not be construed to limit the scope in any manner. It will also be understood that other embodiments may be utilized without departing from the scope of the present invention, and that the detailed description is not to be taken in a limiting sense, and that elements may be differently positioned, or otherwise noted as in the appended claims without requirements of the written description being required thereto.
Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding embodiments of the present invention; however, the order of description should not be construed to imply that these operations are order dependent.
A permanent magnet unit 50 rests in the gap 20, in order to cause a magnetic bias of the inductance 1. This permanent magnet unit 50 has a particular design and consists of a multiplicity of individual permanent magnet elements 51, which are primarily and preferably exclusively stacked spaced apart next to one another in one direction, wherein this one direction is at least approximately orthogonal, preferably exactly orthogonal to the mentioned Y-direction.
A coil 30 is wound about the longitudinal limb 10d illustrated on the left in
a shows a perspective representation of the design and alignment of such a permanent magnet unit 50 with individual permanent magnet elements 51 stacked in X-direction, which in the present form are designed as individual permanent magnet strips or as individual permanent magnet lamellae. Each of these individual permanent magnet strips 51 has a width B in X-direction and a height H in Y-direction. The width B can be 0.1 to 5 mm, for example, preferably approximately 0.5 to 2 mm. For the height H, 0.1 to 10 mm can be provided, preferably approximately 0.5 to 5 mm, for example. An insulator 55 is located between the individual permanent magnet strips 51, which insulator can be formed from a plastic film, a paper layer or similar, for example.
Such a permanent magnet unit 50 in block form can be produced for example in that the individual permanent magnet strips 51 are bonded to each other or potted with the insulators 55. The entire permanent magnet unit 50 is inserted in the gap 20 of the entire magnetic circuit 10 in such a manner that the gap 20 is preferably completely filled by the permanent magnet unit 50. It is also possible, however, that one or both front sides 12, 14 are disposed spaced apart from the permanent magnet unit 50, so that a residual interspace to the permanent magnet unit 50 is formed. This residual interspace can also be filled with an insulator, e.g. plastic, for example.
But it was also found to be convenient to use a magnetic material for the permanent magnet unit 50 and therefore for the individual permanent magnet elements 51, which material consists of a combination of rare earths, in particular of SmCo, NdFeB, SmFeN or of hard ferrite, in particular SrFe, BaFe or a mixture of these materials. The first-mentioned materials are characterized by a high magnetic residual flux density and a high magnetic coercitive field strength, wherein the permanent magnets that are produced in this way have a high magnetic energy density.
b illustrates a similar permanent magnet unit 50 as that shown in
d illustrates a 90° rotation of the upper permanent magnet unit 50 to the lower permanent magnet unit 50′. Other angles of rotation, such as 30°, 45° or 60° are also possible, The stacked permanent magnet units 50, 50′ moreover can also have a different height in Y-direction and/or have lamination of different thicknesses, for example.
Although previously only permanent magnet units 50, 50′ have always been described, which have a rectangular outer contour, it is easily possible to provide a cylindrical outer contour. In
c illustrates a similar configuration of the permanent magnet unit 50 as illustrated in
e illustrates a further rectangular body of a permanent magnet unit 50. Now, the insulation layers 55 are inserted into the permanent magnet unit 50 starting from the side facing towards a viewer and the opposite side of
A so-called double comb structure of the permanent magnet unit 50 is illustrated in
Instead of the coaxial structure of the two individual permanent magnet elements 51 shown in
The
In
To clarify the mode of operation of a permanent magnet that has been inserted into a gap of a magnetic circuit according to the present invention, the
b illustrates the same magnet as
c still shows a further subdivided permanent magnet unit 50, i.e. such a one with the 16 individual permanent magnet elements, which are positioned reciprocally in a 4×4 matrix. In
Assuming that the permanent magnet units 50 illustrated in
If a magnetic field with an amplitude of Be=100 mT is applied on the NdFeB magnet shown in
If the magnet illustrated in
For the permanent magnet unit 50 with sixteen individual permanent magnet elements 51 illustrated in
If the permanent magnet unit 50 is further subdivided into individual permanent magnet elements 51, as shown in
It is significantly easier and almost just as effective, if the permanent magnet unit 50, as shown in
If the permanent magnet unit 50 of
With the inductive component 1 according to the present invention, a particular advantage is also to be noted in the fact that a higher fill factor of the permanent magnet unit 50 is accomplished at an almost equally low power loss as with rectangular or cubic individual permanent magnet elements (see
Having described at least one of the preferred embodiments of the present invention with reference to the accompanying drawings, it will be apparent to those skills that the invention is not limited to those precise embodiments, and that various modifications and variations can be made in the presently disclosed system without departing from the scope or spirit of the invention. Thus, it is intended that the present disclosure cover modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.
Number | Date | Country | Kind |
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10 2013 204 171.3 | Mar 2013 | DE | national |
This application relates to and claims priority as a 371 national-phase from PCT/EP2013/075947 filed Dec. 9, 2013, the entire contents of which are incorporated herein by reference, which claims priority from DE Ser. No. 10 2013 204 171.3 11 filed Mar. 11, 2013.
Filing Document | Filing Date | Country | Kind |
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PCT/EP2013/075947 | 12/9/2013 | WO | 00 |