EP2463869B1 - Inductive component with improved core properties - Google Patents

Description

The invention relates to an inductive component with a winding and a core.

Inductive components such as chokes, transformers and transformers are widely used in electrical and electronic circuits. The electrical properties of the inductive components depend on their structure and the properties of the windings and the core.

The document DE 10212930 A1 shows an inductive component with a center piece and an outer sleeve. The latter has a permanent magnet portion which is glued to another portion.

The document US 2008/0055034 A1 shows a component having a core, which has a part with double T-shaped cross-section and a separate sintered outer shell, which surrounds the coil outer side.

The document EP 1211700 A2 shows a device with a multi-part ferromagnetic core, which also has a magnetic part.

The document US 4943793 A shows a component with a core, in which the material properties of the center column, top and bottom of which differ from the side walls.

The document US 2006/0125586 A1 shows a core with a first part which is embedded in a second part, wherein the material properties of the parts differ.

The document DE 3913558 A1 shows a multi-part ferrite core, in which part cores can be combined with different material properties.

The document US 2011/0121935 A1 shows a core whose inner part of the outer part has different magnetic properties.

The document EP 1061140 A1 shows a cylinder with several regions of different magnetic properties.

The desired inductive properties can be achieved, for example, by suitable choice or adaptation of the winding and / or the permeability. The permeability can be reduced by a large air gap, but this increases the leakage flux in the air gap and concomitant losses. In particular, it is necessary to improve the properties of the magnetic core.

To provide an alternative device, the invention relates to an inductive component having a core comprising a center piece and outer core portions adjacent the center piece at the end, and a winding disposed between the center piece and the outer core portions. The core comprises a plurality of core regions containing different magnetic materials and the centerpiece contains regions of different materials.

There is provided an inductor having a winding and a core comprising a plurality of core regions containing a plurality of different magnetic materials. The inductive component includes the term winding a single-layer and multi-layer winding and one of a plurality of such windings on a core.

Preferably, the different magnetic materials have different magnetic properties. The term different magnetic materials is to be understood to include at least two different magnetic materials or to be a material of a physicochemical composition having partially different magnetic material parameters includes. The parameters can be optimized, for example, with regard to the operating conditions of the areas.

Such a magnetic core can basically comprise any core shape, that is to say, for example, core shapes with the designations C, U, E, P, X, toroidal core and other core forms or core shapes derived therefrom. However, the invention is particularly advantageous to use in core molds having a center column or a center piece. In this context, the other core areas are the legs and the yoke areas connecting them to the center piece. Typically, the entire core is formed from two core halves, each comprising legs, yokes, and a center piece. Alternatively, the core may include a center piece and separate outer core parts. Other forms of separation are conceivable.

In the core of the inductive component, the center piece itself contains different materials or the center piece contains a different magnetic material than the other areas of the core or the core is made up of a combination of both alternatives.

In this case, the different materials may be layered in a preferred embodiment, the layers of which are arranged one behind the other in an alternating sequence, for example in the axial direction of the center column. These layers may be disc-shaped and alternately contain a high permeability layer and a low or no permeability layer. Another preferred embodiment includes a center piece of magnetic material that is different than the magnetic material of the other core portions. Another preferred Embodiment contains combinations of the two aforementioned embodiments. The mechanical connection of the Mittelbutzens with the other core areas is done either by gluing or screwing. In a screw the center piece preferably has a central hole through which a plastic screw is inserted, which holds the core together. Alternatively, the parts can also be connected by latching or bracing. This is expedient in particular in the case of two mutually set core halves, because then the one plastic screw simultaneously holds the two core halves together.

Particularly in the case of transformers and chokes, an air gap is an important functional component, because it considerably reduces the magnetic flux density of the core and, for example, causes a linearization of the magnetization characteristic, so that a magnetic saturation of the core material does not occur until higher field strengths. In the air gap of storage chokes, a substantial portion of the magnetic energy is stored, resulting in disadvantages such as a lower inductance or too high forces. For cores with centerpieces, the air gap is typically located between the two centerpieces of the core halves. The proposed inductive component makes it possible to distribute the air gap virtually over the length of the entire Mittelbutzens. The air gap distributed over several sections may be formed in the center piece by disks, for example of ferrite material, separated by disks of other material.

With the inductive component, it is possible to improve adverse properties of the magnetic core. This includes, in particular, a reduction in the leakage flux and the losses. This will make it possible for those due to the losses conditional higher temperatures and reduce the cost of a cooling system. At the same time, it becomes possible to improve the efficiency of the inductor.

The construction and manufacture of a core for an inductive component are explained purely by way of example in the construction of a magnetic core with center pieces. In particular iron powder material or ferrite material, ie ferromagnetic materials advantageously with high saturation values come into question as different magnetic materials for the core. Both materials have known disadvantages and advantages. Thus, an iron powder core has the disadvantage of brittleness, but the advantage of the high saturation value Bs of 1 Tesla (1 T) to 1.5 T, which can be achieved for example by an iron powder core. The individual powder grains, which are furthermore separated from one another by a nonmagnetic or low-magnetic layer, in themselves cause a distribution of the air gap which brings about an improvement in the saturation induction and a soft use of the saturation. On the other hand, a standard ferrite material has a saturation value Bs of about 0.4 T and a steep saturation behavior.

The use of several different magnetic materials, for example in the center of a magnetic core allows to optimize the magnetic properties of the core. Thus, depending on the structure of the core, the resulting saturation value will be in the range between the saturation value of a ferrite material or a powder material, eg iron powder material. This means that the saturation value will be in the range between 0.4 T and 1.5 T.

wobei µ_tot die Gesamtpermeabilität, I_e,tot die gesamte effektive Länge des Magnetkreises, I_i die magnetische Länge eines i-ten Bereichs und µ_i die Permeabilität des i-ten Bereichs ist.The combination of a lower permeability material for the center wear such as iron powder with an exemplary permeability of 10 to 50 and a ferrite material for the other ranges with an exemplary permeability of 1000 to 3000 allows the total permeability as well as the total length of the air gap or the air gaps in the Compared to a core consisting only of ferrite material to reduce. The total permeability is: $${\mu }_{\mathit{dead}}=\frac{I_{e.\mathit{dead}}}{\left(\frac{I_1}{{\mu }_1}+\frac{{\mathrm{<figure-callout\; id="2"\; label="I"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">I</figure-callout>}}_2}{{\mathrm{<figure-callout\; id="2"\; label="\mu "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\mu </figure-callout>}}_2}+\frac{I_i}{{\mu }_i}+\cdots \right)}.$$

where μ _{tot is} the total permeability, I _{e, tot is} the total effective length of the magnetic circuit, I _{i is} the magnetic length of an ith area, and μ _{i is} the permeability of the ith area.

Due to the shorter overall length of the air gaps in the center piece and the lengths of the partial air gaps are lower, which reduces the leakage flux and the resulting losses.

In turn, optimization of the magnetic core properties makes it possible to reduce the dimensions of the core and in particular to reduce the cross-section or diameters of the centerbody and the winding deposited thereon, which in turn enables a reduction in the volume of the winding. This in turn makes it possible to reduce the overall dimensions of an inductive component and thus also to reduce the costs for the production of the inductive component. Reducing the effective area of the middle brush when using a material Higher saturation value is associated with the increase in saturation value and is for example 0.4T / 1.5T when using a 1.5T material compared to using a 0.4T material. The reduction in the center-line diameter is also accompanied by a reduction in the external dimensions of the component, which allows smaller and more material-saving and thus cost-effective housing to use.

The effective length of the winding is determined by the number of turns and the length of each winding. With a smaller inner diameter of the winding, which is possible due to the slimmer center piece, the overall length of the wire of the winding is therefore reduced. This in turn causes a reduction of the material used for the winding, for example copper, so that a resource-saving production and use of the inductive component is ensured. Therefore, not only the reduced costs for the magnetic core, but also the lower cost of the winding contribute to the reduction of costs and to the advantages of the inductive component. On the other hand, the electrical properties of the inductive component are improved because the smaller overall length of the wire of the winding reduces the losses in the winding and increases the efficiency of the inductive component.

It is advantageous in the inductive component to form the center piece by means of ferromagnetic powder material and the remaining parts of the core of ferrite material. Due to the high saturation value of the middle ear thus created, the saturation behavior of the core as a whole is optimized and the magnetic flux through the center wear can affect the adjacent parts of the core of ferrite material optimally distributed. In order to achieve an optimum transition of flow from the center piece to the adjacent core parts, the center piece is adapted in shape, for example, by a central part of small diameter, which enlarges to the transition to the adjacent ferrite material in the foot area of the center grove. The diameter and thickness of the transition part depend on the limits of magnetic saturation of the two ferromagnetic materials.

Such a transition part between the center piece and the adjacent other core parts is preferably made of the same material as the material in the central part of the Mittelbutzens, so for example of powder material. The transition piece has the advantage that it acts like a flange and is able to guide the winding laterally. Thus, the transition piece fulfills a flange function which is similar to the function of a flange of a winding carrier. This flange-like transition part may have the same outer diameter as the winding. For standard core shapes, such as a P or X core, therefore, a separate winding support is not necessary. However, it is necessary in such a center piece with flanged end function to electrically isolate the center piece and the flange against the winding. For this purpose, the center piece and the flange are coated with an insulating material of small thickness or the coil windings themselves are insulated. This insulating coating material on the elements of the Mittelbutzens has no or at most a low permeability and causes the insulation forms on the front sides of the Mittelbutzens partial air gaps. For example, the coating of the center skin may be 0.2mm thick, which is a common coating thickness. By the Coating an air gap between the center piece and the other core parts is formed.

In an embodiment in which the center piece is formed of discs of different material, it is intended to use disc-shaped magnetic material, for example ferromagnetic powder, and to arrange other discs of low or low-permeability material between the discs made of this material. Such interposed discs of low or low permeability material are also capable of compensating for the differences between the height of the central pillar and the outer core portions. Another function of such a disc-shaped distributed material with little or no permeability in the center piece causes a distributed air gap. Furthermore, the overall permeability can be reduced, the overall length of the air gap reduced, and the magnetic flux optimized.

In the case that the center piece consists of two parts, each formed from a single piece, containing a magnetic material, the finished core composed of two core halves comprises as air gap twice the insulation distance between the two central parts of the center cap and the respective distance between the outer part of the middle ear and the adjacent core parts. By such an arrangement, the leakage flux is further reduced compared to an arrangement with only one air gap. However, a reduction in the leakage flux also means a reduction in losses. In an embodiment in which the permeability is reduced, the center piece comprises two identical or symmetrical parts, between which a disc of material without permeability or is arranged with low permeability. The disc can compensate for differences in fit, for example, between the center piece and the outer portions. Another aspect is that the disc divides the entire air gap into three parts, namely two between the middle-bellied ends and the other core areas and one between the two middle-sized parts, which reduces the leakage flux.

The provision of a plurality of air gaps, a Mittelbutzens of low permeability material, for example, iron powder, or the combination of ferrite regions with iron powder areas as a center piece reduce the leakage flux or losses. The provision of multiple air gaps in the center piece reduces the stray flux, expense and cost of the cooling system and increases the performance of the device.

By constructing the magnetic core in which the center piece contains a material, eg a ferromagnetic powder, and the outer core part contains another material, eg ferrite material, it is possible to optimize the overall permeability of the core. This is possible because ferromagnetic powder, for example, iron powder, has a permeability between 10 and 50, while ferrite material has a permeability in the range of 1000 to 3000. By using a different material for the core, for example in the center piece, it is therefore possible to reduce the total permeability of the magnetic core assembly over a pure ferrite core. At the same time it is possible by such an arrangement, to distribute the entire effective air gap and thus to reduce the leakage flux and the consequent losses.

An inductive component with a magnetic core as proposed also has the advantage that the temperature behavior of the entire core arrangement can be improved. For example, ferrite material has a temperature dependence with several loss maxima. Both by variations in manufacturing, e.g. in pressing and sintering, the ferrite material, as well as by combining with another ferromagnetic material, e.g. Powder material, the overall temperature dependence of the proposed core arrangement can be improved. The permeability may depend on the temperature. For example, ferrite materials can have two tips that can be displaced by varying the manufacturing process. The optimization may be directed to both the center and the other core areas, where the optimization targets, such as saturation, loss, or permeability, may be different for the various core areas. Optimization can reduce total permeability, air gap size and leakage flux. Such an optimization is not possible with cores that consist only of the same material.

The center piece may be constructed in different embodiments and may include, for example, sheets of different material and / or a uniform material that is different from the external core piece. Furthermore, the center piece may include flange-shaped parts at the end. The individual parts of the Mittelbutzens, which are arranged centrally one behind the other along a common axis, can be glued together. However, it is advantageous to provide a central bore for the individual parts of the Mittelbutzens, so that they with a corresponding aligned bore in the external core parts can be connected by a screw. Such a screw is in particular of insulating material and makes it possible to further optimize the total permeability of the magnetic circuit of the inductive component. This is possible, for example, by adjusting the pressure exerted by the screw on the central hole and thus on the different core elements of the central shield and the outer core sections. A change in the pressure exerted by the screw causes a change in the remaining air gap. In particular, if the center piece also includes discs with no or low permeability, it is possible to choose this material so that it is mechanically flexible. As materials in particular plastic and silicone come into question, so that there is quasi a resilient function by the pressure exerted by the screw. The pressure exerted by the screw pressure on the core parts can be adjusted for example with a torque wrench.

In the case that the center pillar contains ferrite or ferrite slices, they may be made so that the minimum of losses occurs at higher temperatures than the ferrite material of the outer core part different therefrom. Therefore, the temperatures of the center grouse in this case may be higher than the temperatures of the outer core part. This provides better cooling conditions for the core assembly, since the center piece can only be cooled by conduction, while the entire core assembly can also be cooled by convection or fan cooling. On the other hand, such ferrite disks of the centerbody can also be made with a material having a higher saturation Bs than the outer core parts. Adapting the ferrite materials of the core regions to their operating temperatures to reduce the losses can be done by adjusting the pressure, the temperature and the sintering profile when sintering the areas. Such a variation of the manufacturing process for different core areas is not possible with a one-piece core. Another approach is to use low permeability material, such as iron powder, to make the center grout which reduces the diameter to reduce the effective turn length, the volume of material for the turn, and ultimately the losses. The combination of different materials, reduced dimensions, and shorter conductor length optimizes the losses, in terms of magnetic material and windings, as compared to a one-piece core component, which also increases efficiency and reduces cost.

Saturation value optimization can be achieved by using different magnetic materials for the different core parts. For example, the ferrite disks in the center piece may be made of a material having a higher saturation value adapted to the operating temperature. The operating temperature of the centerbody is higher than that of the outer core areas; For example, the former is in the range of 100 degrees Celsius, the latter in the range of 80 degrees Celsius. With ferrite material, the saturation value increases with decreasing temperature. For example, the saturation value increases by about 20mT for a common ferrite material with a temperature drop between center and outer core regions.

Embodiments of the invention will become apparent from the figures of the drawing. The same functional elements are represented by the same reference numerals.

Figur 1

eine Drossel mit scheibenförmig aufgebauten Mittelbutzen und verteiltem Luftspalt bei einem P-Kern,

Figur 2

eine Drossel mit X-Kern und scheibenförmig aufgebautem Mittelbutzen mit verteiltem Luftspalt,

Figur 3

eine Drossel mit einer Mittelsäule und einem endseitig angeordneten Flansch,

Figur 4

eine Drossel mit einer Mittelsäule mit endseitigem Flansch und der Funktion eines Wicklungsträgers und

Figur 5

ein Detail des Verlaufs der magnetischen Flussdichte im Übergangsbereich von dem Mittelbutzen mit endseitigem Flansch zu externen Kernbereichen.

Show it:

FIG. 1

a throttle with disc-shaped center pieces and distributed air gap in a P-core,

FIG. 2

a choke with X-core and disc-shaped centerpieces with distributed air gap,

FIG. 3

a throttle with a center column and a flange arranged at the end,

FIG. 4

a throttle with a center column with end-side flange and the function of a winding support and

FIG. 5

a detail of the course of the magnetic flux density in the transition region from the end-to-end center piece to external core regions.

Although the embodiments show cross sections of chokes, it goes without saying that instead of chokes and transformers or transformers can have a corresponding structure. Likewise, different core shapes can be provided, for example with P or X shape or as pot or shell pips. An X-core is understood here to be a core shape which, adjacent to the center piece, comprises at least four radially diverging yoke regions, on each end of which a limb is attached in the direction of the middle grout. P and X cores have a compact shape with little interference.

According to the cross section of FIG. 1 For example, a P-type core is composed of two mutually opposed core parts 1a and 1b which may comprise ferrite material. Centered within the core, a slit is arranged, which is disc-shaped made of different materials. Thus, the center rib contains slices 2 containing either ferromagnetic powder or a ferrite material different from the ferrite material of the outer core part 1a, 1b. Between the discs 2, a material 3 is arranged with little or no permeability. Alternatively, these are discs of said material 3, advantageously flexible, or it is an insulation coating of the ferromagnetic discs 2. Between the center piece and the outer core parts, the winding 5 is arranged. The entire arrangement of the inductive component is held together by a screw 4 in a through hole 6, which connects the outer core parts and the center piece together. By pressure exerted by the pressing force of the screw on the outer core part and the center piece, the air gap, which is distributed and adjusted to the areas with no or low permeability between the ferromagnetic disks and the outer core region.

FIG. 2 shows a throttle assembly in which an X-core is used. The arrangement shows two outer core halves 1a and b, which may comprise ferrite material, and ferromagnetic discs 2 of the centerbody, which are separated from each other by a material 3 with no or low permeability or alternatively by an insulating coating. Between the layer structure of the Mittelbutzens and the outer core parts 1a and 1b, the winding 5 of the throttle is arranged. All parts of the core are screwed through a 4 in a through hole 6 held together and out, with which the pressing force can be adjusted to the elements of the magnetic core. Also in this embodiment results in a spatially distributed air gap.

FIG. 3 shows a reactor with a P or an X-core, in which the external halves 1a and 1b contain ferrite. The central center piece contains two parts 2, which contain a flange 7 at the end to the external core areas. The center piece may include iron powder. The flange 7 causes on the one hand the magnetic flux is better distributed from the center piece to the outer core parts and on the other hand that the winding 5 is at least partially guided.

The insulation of the winding 5 with respect to the core 1 a and 1 b is designed in particular as an insulated winding or as an insulating coating of the Mittelbutzens. In the latter case, it becomes possible to apply the winding directly into the intermediate region between center slug and external core parts. At the same time, the insulation coating of the middle brush fulfills the task of distributing the air gap of the throttle to the central region between the center-half halves and the two outer flange regions. This results in improved loss conditions for the throttle, so that overall a throttle smaller design and improved properties over conventional chokes is achieved. In one embodiment, between the parts 2 of the center cap, a disc of flexible material (in FIG. 3 not shown) whose permeability is low or zero. Due to the flexibility of the disc, this acts as a spring. By the screw can, the flexibility Using the disc, the distance between the parts 2 of the Mittelbutzens be varied.

According to FIG. 4 an arrangement with P- or X-core shape is shown, which differs from the FIG. 3 differs in that the flange-shaped portions 7, which are arranged end between the Mittelbutzenteilen 2 and the external core parts 1 a and 1 b, extending from the central bore 6 with the guide screw 4 toward the external core parts. This makes it possible to arrange the winding 5 completely in the area formed by the flanges and thus to dispense with a separate winding support for the winding. The step-shaped enlarged diameter of the center cap 2 acts as a transition area for distributing the flow and holding the coil 5. Together, the center portion of the center cap 2 and the steps thus define the shape of the coil 5.

FIG. 5 shows schematically the transition of the magnetic flux from the center piece 2 via the end arranged on this center piece 2 flange toward the external core parts. As shown purely schematically with reference to the arrows 8, the very large magnetic flux in the middle section 2 is already reduced and distributed in the transition region of the flange 7, so that an adaptation to the existing in the outer ferrite part 1 of the core flow is ensured. In one embodiment, the center piece 2 comprises iron powder; the other parts of the core include ferrite material. The transition region optimizes the flow transition between the parts, where it is necessary to distribute the flow from the center slug 2 of higher saturation value due to the iron powder to the lower saturation ferrite material. The thickness and diameter of the Transition regions depend on the ratio of the saturation values in the center slug 2 and the other core parts.

LIST OF REFERENCE NUMBERS

1, 1a, 1b

core part

2

middle bleb

3

material

4

screw

5

winding

6

hole

7

flange

8th

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Claims (13)

1. Inductive component comprising a core, comprising a center leg (2) and outer core parts (1a, 1b) adjoining the center leg (2) at the ends, and a winding (5), which is arranged between the center leg (2) and the outer core parts (la, 1b), wherein the core comprises a plurality of core areas (1, 2) which contain different magnetic materials, and the center leg (2) contains areas with different materials.
2. Inductive component according to Claim 1,
   wherein the different magnetic materials have different magnetic characteristics.
3. Inductive component according to Claim 1 or 2,
   wherein the different magnetic materials comprise a material type with different magnetic parameters.
4. Inductive component according to one of Claims 1 to 3,
   whose magnetic core characteristics are different to the magnetic core characteristics which are associated with each individual one of the different magnetic materials.
5. Inductive component according to one of Claims 1 to 4,
   wherein, in the case of the center leg, a layer sequence of different materials is adhesively bonded or screwed to one another.
6. Inductive component according to one of Claims 1 to 5,
   wherein the different magnetic materials of the center leg are in the form of a sequence of layers.
7. Inductive component according to one of Claims 1 to 6,
   wherein the center leg (2) is composed of a magnetic material which differs from a magnetic material of the outer core areas.
8. Inductive component according to Claim 7,
   wherein the center leg (2) contains a ferromagnetic powder, and the outer core areas contain ferrite.
9. Inductive component according to Claim 7 or 8,
   wherein the center leg (2) contains a plurality of layers which are in the form of disks and are composed of magnetic material.
10. Inductive component according to one of Claims 7 to 9,
    wherein the magnetic materials of the center leg (2), which are in the form of disks, are provided with an insulating coating (3).
11. Inductive component according to one of Claims 1 to 9,
    wherein a flexible material (3) of low or zero permeability is arranged between areas of material with higher permeability (2).
12. Inductive component according to one of the preceding claims,
    wherein the center leg (2) has two parts, the center leg having two parts (2) composed of material with higher permeability, between which a disk composed of flexible material with low or zero permeability is arranged.
13. Inductive component according to one of Claims 7 to 12,
    wherein the center leg has a formed-out area (7) in the form of a flange at the end facing the outer core areas.

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