Transformer

Abstract

The invention relates to a transformer (3). The transformer (1) comprises a magnetic core (1), a coil (9) which runs around a core section of the magnetic core (1), and a filler layer (11) which is arranged between the core section and the coil (9) and is produced from a magnetizable material.

Description

[0001] The invention relates to a transformer.

[0002] A transformer typically has a magnetic core, around which at least one primary coil and at least one secondary coil run. The magnetic core is typically made of electrical steel to counteract eddy currents in the magnetic core. For this purpose, layers of electrical steel are laminated and joined together to form the magnetic core, electrically insulated from each other. The magnetic core thus has a surface with edges and / or steps formed by the layers of electrical steel.

[0003] Such transformers are already known from DE 102007054917 A1 and EP 3001435 A1. A disadvantage of the prior art is that these transformers create air-filled gaps between the coils and the surface of the magnetic core, which remain unused for conducting magnetic flux.

[0004] The invention is based on the object of providing a transformer which is improved with regard to the conduction of a magnetic flux.

[0005] The object is achieved according to the invention by a transformer having the features of claim 1.

[0006] Advantageous embodiments of the invention are the subject of the subclaims.

[0007] A transformer according to the invention comprises a magnetic core, a coil extending around a core portion of the magnetic core, and a filling layer arranged between the core portion and the coil, which filling layer is made of a magnetizable material, wherein the filling layer is produced by pressing and sintering a soft magnetic powder composite material.

[0008] The magnetizable filler layer fills an otherwise air-filled space between the magnetic core and the coil of the transformer with magnetizable material. The filler layer supports the conduction of magnetic flux in the magnetic core of the transformer by increasing the cross-sectional area enclosed by the coil, which is filled with magnetizable material. Compared to a conventional transformer without a magnetizable filler layer, less electrical steel sheet is required to achieve the same magnetic flux, especially for the same coil diameter. This allows material and costs for the production of the magnetic core to be saved without increasing the electromagnetic induction in the magnetic core. Furthermore, support structures in the transformer such as pressboard or paper cylinders can be reduced, as their function can be partially taken over by the filler layer.This can also reduce the costs of manufacturing the transformer.

[0009] Soft magnetic materials are easily magnetized in a magnetic field and are therefore particularly well-suited as a material for the filler layer. Soft magnetic composite materials have the particular advantage of having significantly higher permeabilities than air and can be pressed and sintered as powder. By pressing and sintering a soft magnetic powder composite, the filler layer can therefore be easily manufactured as a molded part, even allowing for filler layers with complex three-dimensional geometries.

[0010] In one embodiment of the invention, the filling layer completely fills a space between the core section and the coil.

[0011] The aforementioned embodiment of the invention advantageously utilizes the entire gap between the magnetic core and the coil to conduct the magnetic flux. This optimizes the effect of the filler layer.

[0012] In a further embodiment of the invention, the filling layer is made of a paramagnetic material.

[0013] By using a paramagnetic material, the magnetization of the filler layer follows the magnetic field generated by the coil and thus advantageously increases the magnetic flux conducted by the magnetic core.

[0014] In a further embodiment of the invention, the filling layer has a higher permeability than air.

[0015] The aforementioned embodiment of the invention takes into account that the filler layer only improves the conduction of magnetic flux compared to a transformer with an air-filled gap between the magnetic core and the coil if the filler layer has a higher permeability than air. The higher this permeability, the more the filler layer contributes to conducting magnetic flux and relieves the load on the magnetic core, meaning the more electrical sheet can be saved for the production of the magnetic core.

[0016] According to the invention, the filler layer is made of a soft magnetic material. Particularly preferably, the filler layer is made of a soft magnetic composite material. Soft magnetic composite material is also referred to as a soft magnetic composite (SMC). Preferably, a soft magnetic composite material is used that has high mechanical strength and high magnetic permeability.

[0017] In a further embodiment of the invention, the filling layer has an outer surface facing away from the core section, which has the shape of a cylinder with a smooth, preferably oval and in particular circular guide curve.

[0018] The filling layer thus advantageously receives a smooth outer surface around which the coil can be arranged without gaps, in contrast to the surface of a magnetic core made of electrical steel.

[0019] In a further embodiment of the invention, the magnetic core is made of electrical sheet.

[0020] As already explained above, the magnetic core of a transformer is typically made of electrical steel to counteract eddy currents in the magnetic core and, as a result, has edges and / or steps. The invention enables the gaps between the magnetic core and the coil that occur in such a magnetic core to be filled with the filler layer.

[0021] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of exemplary embodiments, which are explained in more detail in conjunction with the drawings. FIG 1 a cross-sectional view of a magnetic core of an embodiment of a transformer, FIG 2 a perspective sectional view of an embodiment of a transformer.

[0022] Corresponding parts are provided with the same reference numerals in the figures.

[0023] Figure 1 (FIG 1 ) shows a cross-sectional view of a magnetic core 1 of an embodiment of a transformer 3 according to the invention (see Figure 2 The magnetic core 1 is made of electrical steel sheet by laminating layers of electrical steel sheet (not shown in detail) and joining them together in an electrically insulated manner. The layers of electrical steel sheet are designed and arranged with different widths such that the cross-section of the magnetic core 1 approximates a circular surface. Due to the layering of the electrical steel sheet, the surface of the magnetic core 1 has edges 5 and steps 7.

[0024] Figure 2 (FIG 2) shows a perspective sectional view of an embodiment of a transformer according to the invention 3.

[0025] The transformer 3 comprises a magnetic core 1, a coil 9 extending around a core section of the magnetic core 1 and a magnetizable filling layer 11 arranged between the core section and the coil 9. The magnetic core 1 is like the one shown in FIG. Figure 1 described magnetic core 1.

[0026] The filler layer 11 completely fills a space between the core section and the coil 9. The filler layer 11 is made of a paramagnetic material, for example, a soft magnetic material that has a higher permeability than air. The filler layer 11 is particularly preferably made of a soft magnetic composite material (SMC), in particular by pressing and sintering a soft magnetic powder composite material. The filler layer 11 has an outer surface 13 facing away from the core section, which has the shape of a cylinder with an oval, in particular circular, guide curve 15.

[0027] The filler layer 11 supports the conduction of a magnetic flux of the magnetic core 1 of the transformer 3 by completely filling the cross-sectional area enclosed by the coil 9 with magnetizable material. Compared to a conventional transformer without the filler layer 11, less electrical steel is required to achieve the same magnetic flux for the same coil diameter. An example calculation for a magnetic core 1 with a diameter of 29 cm, a cross-sectional area of ​​587.5 cm² and a permeability of 2000 and a cross-sectional area enclosed by the coil 9 of 660.5 cm² shows that the cross-sectional area of ​​the magnetic core 1 can be reduced by approximately 1.3% in order to achieve the same magnetic flux with a filler layer 11 as without the filler layer 11, if the filler layer has a permeability of 200.Furthermore, a simulation based on a finite element method shows that, in this example, due to the increased effective cross-section for conducting the magnetic flux due to the filler layer 11, the magnetic flux density in the magnetic core 1 decreases from 193.7 mT to 189 mT, i.e., by 2% compared to a design without the filler layer 11, with the same excitation by an electric coil current of 12 kA, and the magnetic core 1 is correspondingly relieved of stress. A filler layer 11 with an even higher permeability coefficient enables a further reduction in the cross-sectional area of ​​the magnetic core 1 and thus a corresponding reduction in the amount of electrical steel sheet required to manufacture the magnetic core 1, or an even greater reduction in the load on the magnetic core 1.

[0028] Although the invention has been illustrated and described in detail by means of preferred embodiments, the invention is not limited by the disclosed examples and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention as defined by the claims.

Claims

1. Transformer (3), comprising - a magnetic core (1), - a coil (9) extending around a core section of the magnetic core (1) and - a filling layer (11) arranged between the core section and the coil (9) and produced from a magnetizable material, characterized in that the filling layer (11) is produced by pressing and sintering a soft-magnetic powder composite material.

2. Transformer (3) according to Claim 1, wherein the filling layer (11) completely fills an intermediate space between the core section and the coil (9).

3. Transformer (3) according to Claim 1 or 2, wherein the filling layer (11) is produced from a paramagnetic material.

4. Transformer (3) according to one of the preceding claims, wherein the filling layer (11) has a greater permeability number than air.

5. Transformer (3) according to one of the preceding claims, wherein the filling layer (11) has an outer surface (13) which is facing away from the core section and has the form of a cylinder with a smooth trajectory (15).

6. Transformer (3) according to Claim 5, wherein the trajectory (15) is oval, in particular circular.

7. Transformer (3) according to one of the preceding claims, wherein the magnetic core (1) is produced from electrical sheet.

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