1. Field of the Invention
The present invention relates to a plate-shaped leakage structure as an insert in a magnetic core of an inductive component, to a magnetic core having a plate-shaped leakage structure, and to an inductive component. The present invention particularly relates to chokes and transformers with a plate-shaped leakage structure inserted into same, for a facilitated adaptation of leakage path guidances, and for obtaining high, adjustable leakage inductance values.
2. Description of the Related Art
Inductive components are configured as chokes and transformers having magnetic cores. In general, a magnetic core of an inductive component is made of a ferromagnetic material, e.g. iron powder or ferrite, and serves to guide the magnetic field, while the magnetic coupling between the windings, and turns of individual windings, is improved at the same time. The winding is, in this case, formed of a conductive material, e.g. copper or aluminum, and has the shape of a flat wire, a round wire, a braided wire or a film wire.
A smoothing choke represents a specific example for an inductive component, which is used for the reduction of the residual ripple of a direct current with a superimposed ripple current. Smoothing chokes are used, for example, for voltage converters, or generally for components in which current fluctuations are not desired.
However, in various cases of application a limitation of the magnetic coupling in inductive components is only desirable to a limited extent. In transformers, for example, a certain degree of leakage inductance as current limitation in the event of a short circuit is generally desirable. For example, differential-mode interferences in current-compensated chokes are suppressed by predetermined leakage inductances. In current doubler circuits, for example, smoothing chokes are configured as coupled inductors with leakage path. It is hence common practice in many cases to adopt measures, when designing an inductive component, which reduce the magnetic coupling and increase the leakage inductance.
A simple option for increasing the leakage inductance is the reduction of the magnetic coupling between the windings by spacing the windings apart, and by interleaving them to a smallest possible extent. However, this measure helps to obtain only a very small and limited increase of the leakage inductance. To further increase the leakage inductance, moreover, discrete leakage paths of a material having a magnetic permeability <1 are introduced into a magnetic core between the windings. In many cases, air gaps are incorporated in the leakage path so as to prevent an excessive magnetic flow through the leakage path, so that the leakage inductance is effectively limited. In known E-core configurations the main and leakage inductances are adjusted, for example, by providing a winding around the outer legs, and by providing air gaps in the center leg and/or the outer legs. These known magnetic cores have the drawback, however, that they have poor mechanical properties due to the air gaps formed in the magnetic core, and are easily damaged when subjected to mechanical loads. Moreover, for adjusting the desired leakage inductance values, frequently large dimensions have to be chosen for corresponding magnetic cores, so that correspondingly produced inductive components are still in need for a very large installation space.
In other known inductive components, conventionally, leakage elements are arranged as separate core segments between the center leg and outer leg(s), wherein leakage inductances are determined by the air gaps formed between center legs, outer legs and leakage segments. In this case it has shown, however, that air gaps only have a poor homogeneous adjusting capacity, and correspondingly manufactured components go into saturation very early, with the leakage inductance slowly decreasing. This is not acceptable for a great number of applications. Due to the tolerances in the air gap, which are unavoidable in these magnetic cores, a series production is only difficult to control.
Proceeding from the conventional magnetic cores and inductive components as described above there is, therefore, a demand for a magnetic core and an inductive component in which the leakage inductance can be adjusted very accurately and reproducibly. At the same time, corresponding magnetic cores are suitable for series production.
According to aspects of the present invention, the a plate-shaped leakage structure as an insert in a magnetic core for an inductive component is provided, wherein the plate-shaped leakage structure is passed through along its thickness direction by at least one spacer having (as opposed to the rest of the material of the leakage structure) a very low magnetic permeability.
In a first aspect of the present invention, a plate-shaped leakage structure may be provided as an insert in a magnetic core for an inductive component. In embodiments herein, the plate-shaped leakage structure may comprise a first leakage structure portion and a second leakage structure portion, each formed of a first material, and a first spacer formed of a second material which, as opposed to the first material, may have a lower magnetic permeability. The first spacer may separate the first leakage structure portion from the second leakage structure portion, and may pass through the leakage structure along the thickness direction thereof. The plate-shaped leakage structure may provide for a leakage path that may be inserted into a magnetic core of an inductive element, allowing for a very exact and reproducible adjustment of leakage inductances without reducing mechanical and/or magnetic properties of a magnetic core to be produced. The plate-shaped leakage structure may be further easily adapted, even during subsequent production processes, allowing the adjustment of a desired leakage inductance value and/or desired geometrical dimensions of the leakage structure on the basis of a predetermined design.
In a second aspect of the present invention, a magnetic core may be provided. In embodiments herein, the magnetic core may comprise a first core section having a first core leg, and a second core section having a second core leg. The magnetic core may further comprise a plate-shaped leakage structure according to the first aspect. The plate-shaped leakage structure may be arranged between the first core section and the second core section, so that each core section rests on a bearing surface of the leakage structure. In a bearing surface of the plate-shaped leakage structure, the first core leg may cover a first surface section formed of an exposed first material. In the opposite bearing surface, the second core leg may cover a second surface section formed of an exposed first material.
Thus, very compact components may be provided, the leakage inductance of which may be constant to a great extent and may only decrease later.
In a third aspect of the present invention, an inductive component may be provided. In embodiments herein, the inductive component may comprise a magnetic core according to the second aspect, a first winding provided on the first core leg, and a second winding provided on the second core leg. The leakage structure may be arranged in the magnetic core between the first and the second winding. Thus, inductive components with an advantageous leakage path guidance may be provided.
Additional features, advantageous embodiments and advantages of the present invention are described in the accompanying patent claims and may be understood from the detailed description of illustrative embodiments as given below with regard to the figures. In the figures:
Described below are various illustrative embodiments of the present invention, wherein in the interest of clarity, not all features of an actual implementation are described. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the specific goals of the developer, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skills in the art having the benefit of this disclosure.
The present invention will now be described in greater detail with reference to the attached figures. Various structures, components and devices are schematically depicted in the drawings for purposes of explanation only and so as to not obscure the present disclosure with details which are well-known to those skilled in the art. Nevertheless, the attached drawings are included to describe and explain some illustrative examples of the present invention as will be described below in greater detail. The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases used by the person with skills in the relevant art. No special definition of a term or phrase, i.e., a definition that is different from the ordinary or customary meaning as understood by the skilled person, is intended to be implied by a consistent usage of the term or phrase herein. To the extent that a term or phrase is intended to have a special meaning, i.e., a meaning other than that understood by skilled artisans, such a special definition shall be expressively set forth in the specification in a definitional manner that directly and unequivocally provides the special definition for the term or phrase.
In accordance with some illustrative embodiments of the first aspect of the present invention as described in section “Summary of the Invention” above, the first spacer may have a hollow-cylindrical configuration, which makes the leakage structure advantageously insertable in magnetic cores with core legs, which cores having a round cross-section and/or a round overall configuration, e.g. pot cores and cup cores.
In some illustrative embodiments of the first aspect, the leakage structure may have a cylindrical configuration. The leakage structure may thus be particularly suitable as an insert in pot and cup cores.
In some illustrative embodiments of the first aspect, the leakage structure may further comprise a second spacer formed of a second material, and a third leakage structure portion formed of the first material. The second spacer may separate the third leakage structure portion from the second leakage structure portion and may pass through the leakage structure along the thickness direction thereof. Thus, an advantageous leakage structure may be created for use in magnetic cores that are formed of E- and/or C-cores.
In some illustrative embodiments of the first aspect, a spacing of the leakage structure portions may be smaller than a thickness of the leakage structure defined along the thickness direction thereof. The person skilled in the art will appreciate that a thickness of a plate-shaped body, respectively, the thickness direction thereof, may be generally understood as the dimension of the leakage structure transversely to the large-area surfaces thereof, as will be described below. A corresponding spacing may effectively limit the leakage inductance of the leakage structure.
In some illustrative embodiments of the first aspect, the first material may comprise a ferrite material, and the second material may comprise a ceramic material or plastic material. Respective leakage structures may have advantageous magnetic properties and may be, at the same time, easily produced.
In some illustrative embodiments of the first aspect, the spacers may be sintered into the leakage structure. Thus, a mechanically stable leakage structure with easily predeterminable mechanical and magnetic properties may be provided, which may be also easily adapted during subsequent production phases.
In accordance with some illustrative embodiments of the second aspect of the present disclosure as described in section “Summary of the Invention” above, the first core section may further comprise a third core leg which covers, beside the first core leg, a third surface section formed of an exposed first material. The third surface section may be separated from the first surface section by a surface section formed of an exposed second material. Consequently, a leakage path with a gap may be easily provided between the first and third core leg, as the first and third core leg may each rest on leakage sections which are spaced apart by the spacer. Hence, a leakage path guidance may be provided between two core legs.
In some illustrative embodiments of the second aspect, the second core section may further comprise a fourth core leg which covers, beside the second core leg, a fourth surface section formed of an exposed first material. The fourth surface section may be separated from the second surface section by a surface section formed of an exposed second material. Consequently, a leakage path with a gap may be easily provided between the second and fourth core leg, as the second and fourth core leg each may rest on leakage sections which are spaced apart by the spacer. Hence, an advantageous leakage path guidance may be provided between two core legs.
In some illustrative embodiments of the second aspect, the magnetic core may be configured as a pot core or cup core, and the plate-shaped diffuser is cylindrical. Thus, pot or cup cores with advantageous leakage paths may be provided.
In some illustrative embodiments of the second aspect, the magnetic core may have a double E-, double C- or E-C-core configuration, and the plate-shaped leakage structure may have two spacers. Thus, an advantageous leakage path guidance may be provided, wherein, at the same time, a great mechanical stability for a great number of core configurations may be provided.
In some illustrative embodiments of the second aspect, the leakage structure in the magnetic core may be arranged in an air gap formed by the first and second core leg. This may permit a further compact design.
In accordance with some illustrative embodiments of the third aspect of the present disclosure as described above in section “Summary of the Invention” above, an inductive component may be provided. In embodiments herein, the inductive component may comprise a magnetic core according to the second aspect, a first winding provided on the first core leg, and a second winding provided on the second core leg. The leakage structure may be arranged in the magnetic core between the first and the second winding. Thus, inductive components with an advantageous leakage path guidance may be provided.
In some illustrative embodiments of the third aspect, the inductive component may be configured as a smoothing choke. Thus, a smoothing choke with an advantageous leakage path guidance may be provided.
The person skilled in the art will appreciate that, in some aspects of the present disclosure, very compact components with very good leakage path guidance may be provided by means of a plate-shaped leakage structure, without the plate-shaped leakage structure having a negative effect on the mechanical stability. Accordingly provided components may be suitable for the series production of inductive components due to easily adjustable mechanical and magnetic properties, which, according to the present disclosure, may be subject to small production tolerances. It may thus be possible to produce chokes and transformers with a leakage path guidance that may be easily adjusted, the produced transformers and chokes involving only small production tolerances. At the same time, magnetic leakage properties may be adjusted easily and in flexible manner.
The person skilled in the art will appreciate that the expression “plate-shaped” may be understood as “similar to a plate”, and that, thus, curvatures in surfaces and/or edges are not precluded. A “plate-shaped structure” is to be understood as a geometrical structure which has dimensions along three mutually perpendicular directions, one of the three dimensions being substantially smaller than the other two dimensions. For example, a plate-shaped structure may be understood as cuboid-shaped (similar to a cuboid), with one dimension being substantially smaller than the dimensions perpendicular thereto. The expression “substantially smaller” is to be generally understood as <1. For example, a ratio of a dimension ‘a’ to a dimension ‘b’, which is substantially smaller than the dimension ‘a’, may be smaller than 1, and in particular smaller than 0.5 or 0.25 or 0.1. In an illustrative example, a ratio of the substantially smaller dimension to the greater one from the two other dimensions may be, for example, smaller than 0.2. Below, the dimension that is substantially smaller than the two other dimensions will be referred to as “thickness”, and the corresponding direction in which the dimension is defined will be referred to as “thickness direction”. Equally, the longer dimension of the two other dimensions will be referred to as “length”, and the direction in which the length is defined will be referred to as “length direction”. The remaining dimension will be referred to as “width”, and the corresponding direction in which the width is defined will be referred to as “width direction”. In cases in which length and width are equal, both will be referred to as “radius”, and the corresponding direction will be referred to as “radial direction”. In addition or as an alternative to the above definition of “plate-shaped”, the person skilled in the art will appreciate that a “plate-shaped structure” has two opposing lateral faces, and the rest of the lateral faces (in terms of the area measures) are substantially smaller than the opposite lateral faces.
Below, different illustrative embodiments of the invention will be described by means of
The embodiment shown in
The core portions 3 and 5 of the plate-shaped leakage structure 1 may be formed of a material which has a higher permeability than the material of the spacer 7. In other words, the spacer 7 may be formed of a material which has a lower magnetic permeability than the core portions 3 and 5. The core portions 3 and 5 are, for example, may be formed of ferromagnetic or ferrimagnetic material. According to an illustrative example herein, the core portions 3 and 5 may be formed of a ferrite material, e.g. by means of sintering. Alternatively, the leakage structure portions 3 and 5 may be formed of a superparamagnetic material. As opposed to this, the spacer 7 may be formed, for example, of a ceramic material or plastic material.
To produce the plate-shaped leakage structure 1, the leakage structure portions 3 and 5 may, in accordance with an exemplary embodiment, each be formed by sintering a ferrite material. In this case, it should be assured that the correspondingly formed second leakage structure portion 5 may be inserted into a recess which centrally passes through the first leakage structure portion 3. The recess passing there through may be subsequently introduced into the sintered leakage structure portion 3, or may be realized by a mold for forming annular sintered compacts. During the production of the plate-shaped leakage structure 1, a diameter of the second leakage structure portion 5 may be defined such that the second leakage structure portion 5 may be arranged in the first leakage structure portion 3 without any contact between the two leakage structure portions. The person skilled in the art will appreciate that a ring diameter for, respectively, the thickness of the spacer 7 may be defined by a distance between the first leakage structure portion 3 and the second leakage structure portion 5 in the recess, in particular by a diameter of the recess (along D in
The spacer 7 may be formed in a subsequent process step, with a second material being introduced into an air gap formed between the first leakage structure portion 3 and the second leakage structure portion 5. For example, the second material may be filled into the air gap in a solid or liquid form. According to some illustrative embodiments, solid material, e.g. provided as a powder, may be liquefied and cured in the gap. The spacer 7 may be formed once the second material in the gap has cured. Alternatively, a prefabricated ring body may be installed as spacer 7, which requires a high precision for fabricating the ring body. In other alternative embodiments a cylindrical spacer may be formed in the recess passing through the leakage structure portion, e.g. a prefabricated cylindrical spacer is arranged in the recess, or is formed by filling in a second material. Subsequently, a recess passing through the spacer may be provided in the cylindrical spacer arranged in the recess and/or fixed in same, in which the first leakage structure portion 5 is arranged. It is to be noted that spacers 7, which may be formed subsequently by filling a second material into the annular air gap between the leakage structure portions 3, 5, may be formed in an easy and fast manner. Desired thicknesses of the spacer 7 may be easily adjusted by accordingly treating the recess in the leakage structure portion 3 and/or the circumferential surface of the leakage structure portion 5. Production tolerances may, accordingly, be very small, and leakage inductances may be adjusted with great accuracy.
The plate-shaped leakage structure 2 is formed of three leakage structure portions 11, 13 and 15. The leakage structure portions 11, 13, 15 may be formed of a first material. A spacer 17 may be arranged between the leakage structure portions 11 and 13. The leakage structure portions 13 and 15 may be spaced apart from one another by a spacer 19. The spacers 17 and 19 may be made of the second material. With regard to the first and second materials, reference may be made to the foregoing description. One surface section of the leakage structure portion 11 in an upper surface of
The plate-shaped leakage structure 2 may be formed, for example, by alternate layers made of the first and second material and subsequent sintering, with the spacers 17 and 19 being sintered into the leakage structure 2. Alternatively, the leakage structure sections 11, 13 and 15 and the spacers 17 and 19 may be each produced separately and, subsequently, connected to one another, for example, in a gluing process or in an additional sintering process.
In the following process steps, the leakage structures 1 or 2 may be modified by subsequent adaptations such that a desired leakage inductance or saturation limit of the leakage inductance may be suitably adjusted. For example, by adapting the spacers in the plate-shaped leakage structure 1 or 2, a modification of the leakage inductance may be obtained. Increasing the saturation limit for the leakage inductance may be achieved by adapting the thickness of the plate-shaped leakage structure 1 or 2. Thus, specific magnetic properties of the plate-shaped leakage structure may also be adapted in subsequent processing steps, so that the plate-shaped leakage structures 1 and 2, as provided according to the present disclosure, may provide for leakage inductances, and saturation limits for leakage inductances, along with very small production tolerances. The person skilled in the art will appreciate that the leakage inductance and saturation limit may be adjusted by appropriately dimensioned leakage structure sections and/or spacers.
Below, magnetic cores and inductive components in accordance with illustrative embodiments of the invention will be described with reference to
In the cross-sectional view according to
According to the illustration in
The windings W1 and W2 are provided on the center legs 114, 124, whereby the windings W1 and W2 may be separated by the interposed leakage structure 130. The windings W1 and W2, whose coupling in the inductive component is to be reduced, may be provided on both sides of the leakage structure 130, as illustrated, so that the plate-shaped leakage structure spaces the windings W1 and W2 apart from one another. Additionally or alternatively, windings may be provided on the outer legs.
In the cross-sectional view according to
According to the illustration in
The inductive component illustrated in
In the inductive component illustrated in
The person skilled in the art will appreciate that, if a modification of the leakage inductance in inductive components is desired, this may be easily accomplished by appropriately adapting the inserted leakage structures 130, 230. Moreover, the inductive components according to the present disclosure, as illustrated in
In the above description, reference is made to a first material and a second material. The first material may have a higher magnetic permeability than the second material. The person skilled in the art will appreciate that this does not pose any limitation on the present disclosure, and more than a first material and/or more than a second material having according magnetic properties may be provided.
With reference to
With reference to
Summarizing, the present invention provides, in various aspects, a plate-shaped leakage structure as an insert in a magnetic core of an inductive component, a magnetic core having a plate-shaped leakage structure, and an inductive component. A plate-shaped leakage structure may, in this case, be provided as an insert in a magnetic core, which leakage structure being passed through, along the thickness direction thereof, by at least one spacer having a very low magnetic permeability (as opposed to the rest of the material of the leakage structure). In a magnetic core according to an aspect of the present disclosure, core legs may be arranged above opposite bearing surfaces of the plate-shaped leakage structure, the plate-shaped leakage structure providing a leakage path between the core legs. In a special illustrative example herein, the plate-shaped leakage structure may be a leakage plate with at least one integral gap passing through the leakage plate along the thickness direction thereof and being formed of a material of a low magnetic permeability. The gap may further pass through the leakage plate in the thickness direction thereof, and may be formed as a gap along the longitudinal direction.
The particular embodiments disclosed above are illustrative only, as the invention may be modified in practice and may be practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. For example, the process steps set forth above may be performed in a different order. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.
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20150279552 A1 | Oct 2015 | US |