DE102024106870A1 - Magnetic core for an electrical machine - Google Patents

Abstract

A magnetic core (1A, 1B) for an electrical machine (2) comprises a plurality of elongated, soft-magnetic elements (10A, 10B) which are electrically insulated from one another, at least two of which are arranged offset from one another when viewed in two spatial directions (R, T).

Description

The present disclosure relates in particular to a magnetic core for an electric machine, to an electric machine, to a vehicle and to a method for producing magnetic cores.

Vehicles, especially aircraft, are powered in a wide variety of ways. Internal combustion engines, such as piston engines or gas turbine engines, enable long ranges and high speeds. Electric drive units, on the other hand, enable the use of sustainably generated energy and are sometimes particularly low-maintenance and quiet. Advances in battery and fuel cell technology are opening up ever-expanding areas of application for electric drive units.

For electric motors and other electrical machines, especially electric drive units, the goal can be to continually improve various target parameters, such as energy efficiency, power-to-weight ratio, or service life. At the same time, it may be desirable to manufacture electrical machines as simply and reliably as possible. However, such objectives can conflict with one another.

The task is to enable an improved electrical machine.

According to one aspect, a magnetic core for an electrical machine is specified, comprising a plurality of elongated, soft-magnetic elements that are electrically insulated from one another, of which at least two are arranged offset from one another when viewed in two spatial directions.

This can significantly reduce eddy currents. Magnetic cores can, for example, be manufactured in the form of a laminated core, with the laminations being electrically insulated from one another. The laminations are arranged in such a way that, in the electrical machine, eddy currents are induced in the magnetic core(s) (at most) primarily perpendicular to the plane of the laminations. Segmentation in this direction can significantly reduce the resulting eddy currents. This can reduce losses and the corresponding heat generation. The proposed magnetic core is based on the finding that at high power densities, eddy currents can also play a role, e.g., in laminated cores in one direction within the plane of the laminations, or, more generally, in a second spatial direction, e.g., in a transverse flux machine with offset magnetic cores enclosing a coil (although an application in a radial flux machine or an axial flux machine is also conceivable). By also segmenting in a second spatial direction, losses and heat generation can be reduced even further, which enables a further improved electrical machine.

Viewed in a cross-section through the magnetic core (i.e., through the multiple soft magnetic elements), the soft magnetic elements are arranged offset from one another in two mutually perpendicular directions. The soft magnetic material forming the magnetic core is thus segmented in two mutually perpendicular directions.

Some or all of the soft magnetic elements can have a polygonal, particularly rectangular, cross-section. This enables a particularly high packing density.

For example, the soft magnetic elements are each designed in a strip shape, e.g., in the form of a flat strip. For example, it is provided that at least two strips are arranged one above the other and at least two strips are arranged next to each other.

Alternatively or additionally, some or all of the soft magnetic elements can have a circular, O-shaped, oval, or elliptical cross-section. This allows for particularly simple production of the soft magnetic elements.

The soft magnetic elements, especially those with round or square cross-sections, can have a diameter of less than 5 mm, less than 1 mm, less than 0.5 mm, or less than 0.2 mm. This allows for a high degree of segmentation, which significantly reduces eddy currents. This also simplifies manufacturing and allows for the creation of magnetic cores with complex shapes.

For example, the soft magnetic elements are designed in the form of bent wires. This makes them particularly easy to manufacture and process. For example, a (correspondingly long) wire (or several long wires) is wound multiple times to create a winding.

Furthermore, the soft magnetic elements can be arranged and/or formed in the form of a section of a winding. For example, the initially manufactured winding is cut into several sections, resulting in several winding sections. These can then (optionally after further processing) be used as magnetic cores. This allows multiple magnetic cores to be produced at once.

For example, the soft magnetic elements are glued together, which allows for great stability.

The magnetic core can be C-shaped, I-shaped, or L-shaped (e.g., in cross-section). A pair of such magnetic cores can encompass a coil between them and securely hold it. An I-shaped magnetic core can have (or not have) a terminal piece at both ends and, for example, be shaped like a double-T beam in cross-section.

For example, the soft magnetic elements each comprise or consist of an alloy. The alloy comprises, for example, iron and/or cobalt or consists of them. Such an alloy enables both very good structural and magnetic properties. The soft magnetic elements each have, for example, a layer for mutual insulation, and in particular, are each enclosed by such a layer.

The soft magnetic elements each extend from a first end to a second end. It can be provided that the first ends are enclosed in a shoe and/or that the second ends are enclosed in a shoe. This prevents the open ends of the individual soft magnetic elements from separating from one another, similar to a cable lug. Furthermore, such a shoe can facilitate the assembly of the magnetic core. Alternatively or additionally, the shoes can each form a positive connection with a carrier (e.g., each in the form of a holding plate), e.g., by each of the shoes being inserted into a respective cutout in the carrier.

For example, the shoe of the first ends and/or the shoe of the second ends is/are molded from an SMC material. This allows the respective shoe to be molded particularly easily and securely onto the ends of the soft magnetic elements, while simultaneously securing the soft magnetic elements to each other and to a carrier.

Furthermore, the shoe of the first ends and/or the shoe of the second ends can each have a flange. This enables easy assembly and secure mounting of the magnetic core.

According to one aspect, an electric machine is specified (in particular for an electric drive unit of an aircraft), comprising: a stator with at least one magnetic core according to any of the embodiments described herein, and a rotor rotatably mounted relative to the stator. The magnetic core enables particularly low losses and improved performance. The stability of the magnetic core also allows the magnetic core to assume load-bearing properties, which in turn allows for reduced weight. Furthermore, the magnetic core is easy to manufacture, which subsequently also applies to the electric machine, which can have a large number of magnetic cores.

The electric machine can comprise a plurality of magnetic cores, each of which is attached to two spaced-apart supports. The magnetic cores can hold an electrical coil arranged, for example, between the supports. This enables simple manufacturing and particularly good magnetic properties.

The electric machine can be designed as a transverse flux machine. This enables a particularly high power density.

Alternatively, the electrical machine can be designed as a radial flux machine or an axial flux machine. In these cases, in particular, the magnetic core(s) can be I-shaped.

The electric machine can have a double air gap. For example, the electric machine has an air gap on either side of the magnetic core (or on either side of the plurality of magnetic cores). It can be provided that rotor magnets are arranged beyond each respective air gap (i.e., on either side of the magnetic core or on either side of the plurality of magnetic cores). The two air gaps can each be disc-shaped and/or aligned parallel to each other (e.g., in a transverse flux machine or an axial flux machine). Furthermore, the air gaps can be cylindrical, and one can be arranged within the other (e.g., in a radial flux machine).

According to one aspect, a vehicle, in particular an aircraft, is specified, comprising the electric machine according to any of the embodiments described herein and, for example, a propeller driven thereby. The advantages described above can be particularly evident in vehicles, in particular in aircraft.

According to one aspect, a method for producing a magnetic core for an electrical machine is specified, in particular according to any of the embodiments described herein. The method comprises winding at least one wire, e.g., around a mandrel, to form a self-contained winding body with a plurality of wire windings, wherein the at least one wire comprises a soft magnetic material (and, e.g., at least two of the wire windings are arranged one above the other and at least two of the wire windings are arranged next to one another). The method may comprise compressing the winding body; in this way, the packing density can be increased. The method further comprises dividing the winding body to obtain one or more magnetic cores, each of which comprises a plurality of mutually electrically insulated, elongated, soft magnetic elements. With regard to the advantages, reference is made to the above information.

The method may further comprise the following step of gluing the wire windings together, carried out before or after the dividing step.

The soft magnetic elements each extend, for example, from a first end to a second end, and the method may further comprise the step of enclosing the first ends and the second ends in a respective shoe.

• 1 ein Luftfahrzeug in Form eines Flächenflugzeugs mit zwei elektrischen Antriebseinheiten mit jeweils einer elektrischen Maschine;
• 2 eine aufgeschnittene Ansicht einer elektrischen Maschine des Luftfahrzeugs gemäß 1 mit einem Stator mit mehreren Magnetkernen;
• 3 einen aus mehreren weichmagnetischen Elementen geformten Magnetkern der elektrischen Maschine gemäß 2;
• 4 einen weiteren aus mehreren weichmagnetischen Elementen geformten Magnetkern;
• 5A und 5B verschiedene mögliche Anordnungen der weichmagnetischen Elemente des Magnetkerns gemäß 3 und gemäß 4;
• 6 einen aus mehreren weichmagnetischen Elementen geformten Magnetkern für die elektrische Maschine gemäß 2;
• 7 einen Ziehstein für die Herstellung eines weichmagnetischen Drahts zur Herstellung von Magnetkernen;
• 8 ein Wickeln des Drahts gemäß 7 um einen Dorn zur Herstellung eines Wicklungskörpers;
• 9 ein Zerteilen des gemäß 8 hergestellten Wicklungskörpers zur Ausbildung mehrerer Magnetkerne;
• 10A und 10B ein mechanisches Verbinden mehrerer weichmagnetischer Elemente;
• 11 ein Verfahren zur Herstellung von Magnetkernen; und
• 12 ein Luftfahrzeug in Form eines senkrecht startenden und landenden Flugzeugs.

Embodiments will now be described by way of example with reference to the figures, in which:

• 1 an aircraft in the form of a fixed-wing aircraft with two electric propulsion units, each with an electric motor;
• 2 a cutaway view of an electrical machine of the aircraft according to 1 with a stator with several magnetic cores;
• 3 a magnetic core of the electrical machine formed from several soft magnetic elements according to 2 ;
• 4 another magnetic core formed from several soft magnetic elements;
• 5A and 5B various possible arrangements of the soft magnetic elements of the magnetic core according to 3 and according to 4 ;
• 6 a magnetic core formed from several soft magnetic elements for the electrical machine according to 2 ;
• 7 a drawing die for producing a soft magnetic wire for the manufacture of magnetic cores;
• 8 winding the wire according to 7 a mandrel for producing a winding body;
• 9 a division of the according to 8 manufactured winding body to form several magnetic cores;
• 10A and 10B a mechanical connection of several soft magnetic elements;
• 11 a method for producing magnetic cores; and
• 12 an aircraft in the form of a vertical take-off and landing aircraft.

1 shows an aircraft 3 in the form of an electrically powered aircraft with a fuselage 30 and wings 31.

The aircraft 3 comprises at least one electric drive unit, here several, specifically two electric drive units. Each of the electric drive units comprises an electric machine 2 in the form of an electric motor and a propeller 32. The propellers 32 driven by the respective electric machine 2 generate thrust for the aircraft 3. In the present case, one electric drive unit is mounted on each of the wings 31 of the aircraft 3, although other arrangements are also conceivable. The propellers 32 comprise several, here, for example, three propeller blades, which are mounted on a hub.

In alternative embodiments, the aircraft 3 comprises, for example, a fan instead of a propeller and/or one or more electric drive units, each with at least one propeller, fan or other rotor unit.

Furthermore, the aircraft 3 comprises, by way of example, a battery system 33 (or alternatively or additionally, another energy source, e.g., a fuel cell, a generator, a photovoltaic system, or the like). The battery system 33 stores electrical energy to operate the electric drive units. In this case, the battery system 33 is connected to inverters, which convert a direct voltage from the battery system 33 into an alternating voltage. The alternating voltage is applied to the electric machine 2 of the respective electric drive unit in order to set the respective propeller 32 in rotation and thus drive the aircraft 3.

12 shows an aircraft 3', for example, in the form of an air taxi. The aircraft 3' comprises a fuselage 30' with a cabin and several, here four, electrical machines 2. Each of the electrical machines 2 is designed in the form of an electric motor and comprises several (here two, alternatively e.g. only one) propeller. Each of the electric motors 2 drives the respective propeller(s). A battery supplies electrical power to operate the electric motors 2. The electric motors 2 in this case are direct drives.

In this case, aircraft 3' is trained as a VTOL aircraft, specifically as an eVTOL aircraft. Vertical takeoff and landing aircraft, such as airplanes, are regularly referred to as VTOL aircraft, with the abbreviation VTOL being derived from "Vertical Take-Off and Landing." VTOL aircraft are trained for vertical take-off and landing.

2 shows a simplified representation of the electric machine 2 of one of the electric drive units of the aircraft 3.

The electrical machine 2 is designed here, for example, in the form of a permanent magnet synchronous machine.

The stator 20 is designed for multi-phase, here three-phase, operation and is connected to a three-phase alternating voltage with phases U, V, and W. During normal operation of the electrical machine 2, the coil 200 (or at least a portion of the coils 200) is accordingly supplied with the alternating voltage.

The electrical machine 2, a part of which is shown here, extends around a rotational axis D. The electrical machine 2 is designed in the form of a transverse flux machine, although alternatively, for example, an axial flux machine or a radial flux machine would also be conceivable.

The electric machine 2 comprises a stator 20 and a rotor 21 rotatable about the rotational axis D relative to the stator 20. The rotor 21 is rotatably mounted on the stator 20 by means of bearings 22, here in the form of ball bearings, or alternatively, for example, plain bearings. The rotor 21 surrounds parts of the stator 20. The stator 20 can be mounted (and is mounted in the installed state) on a supporting structure of the aircraft 3 using a bracket.

A shaft can be mounted on the rotor 21. The rotor 21 then drives the corresponding propeller 32 via the shaft.

The stator 20 further comprises at least one, here several, supports 203. The supports 203 are attached to the holder. In this case, the supports 203 are aligned parallel to one another. The supports 203 are each plate-shaped, for example, and are made of PEEK.

The stator 20 has a plurality of magnetic cores 1A. A plurality of magnetic cores 1A are attached to each of the supports 203. In this case, each magnetic core 1A is attached to two supports 203. Each magnetic core 1A extends between two supports 203. The magnetic cores 1A are each engaged with the two supports 203.

Each of the magnetic cores 1A of the electrical machine 2B comprises, as will be explained in more detail below, a plurality of elongated, soft magnetic elements that are electrically insulated from one another, of which at least two are arranged offset from one another when viewed in two spatial directions.

The magnetic cores 1A can also be referred to as iron cores. The magnetic cores 1A are shaped like retaining webs. In the example shown, the magnetic cores 1A are each C-shaped.

Coils 200 of the stator 20 are mounted on the magnetic cores 1A. It is provided that several of the magnetic cores 1A surround the respective coil 200 on opposite sides of the coil 200. The coils 200 extend at least partially around the axis of rotation D. The coils 200 are wound such that they run at least along part of a circle around the axis of rotation D. The magnetic cores 1A of a coil 200 are arranged next to one another around the axis of rotation D. Each of the coils 200 is held between several magnetic cores 200. Each of the coils 200 also runs between the two supports 203 to which the magnetic cores 1A of the coils 200 are attached. The supports 203 each describe at least part of a circular disk.

In this case, the magnetic cores 1A form an inductance together with the respective coil 200. The magnetic cores 1A conduct the magnetic flux of the coil 200. Thus, the magnetic cores 1A have two functions: an electromagnetic one and a mechanical one, namely the support of the coil 200.

If a respective coil 200 is energized, a magnetic field is created which interacts with magnets 210 of the rotor 21 and thus causes the rotor 21 to rotate about the rotation axis D relative to the stator 20. The magnetic cores 1A guide the magnetic field lines.

The three-phase alternating voltage, whose phases U, V, W are each phase-shifted by 120°, generates a magnetic rotating field in the coils 200 during normal operation, which together with the permanently excited magnetic field provided by the rotor 21 so that, in motor operation, a corresponding rotational movement of the rotor 21 relative to the stator 20 can be brought about. In the present case, it is provided that the electric machine 2 serves as the drive motor for the respective propeller 32. It can also be provided that the electric machine 2 can be operated in generator mode. When operated as an electric motor, the electric machine 2 can be supplied with, for example, 100 kW, 1 MW, or even 10 MW.

In the present case, the stator 20 comprises, for example, two coils 200 axially offset along the rotation axis D, although a design with only one such coil 200, viewed along the rotation axis D, is also possible. The rotor 21 has two supports 211 for each of the coils 200. The magnets 210 of the rotor 21 are attached to the supports 211 of the rotor 21.

3 shows one of the magnetic cores 1A of the electrical machine 2. The magnetic core 1A comprises a plurality of electrically insulated, elongated, soft magnetic elements 10A. Viewed in two mutually perpendicular spatial directions R, T, several of the soft magnetic elements 10A are arranged offset from one another. Viewed in a cross-section through the magnetic core 1A (in particular in a sectional plane perpendicular to the axial spatial direction A), the soft magnetic elements 10A are thus arranged next to one another in two mutually perpendicular directions.

In this case, the two spatial directions R, T in the installed state (see 2 ) about a radial spatial direction R, which is oriented perpendicular to the axis of rotation D, and about a tangential spatial direction T, which is oriented perpendicular to the radial spatial direction R and perpendicular to the axis of rotation D.

The magnetic core 1A has a first and a second end. The magnetic core 1A extends from the first end to the second end. The first end is spaced from the second end along an axial spatial direction A, which is aligned parallel to the rotation axis D.

The soft magnetic elements 10A each have a first and a second end 100, 101 and extend from the first end 100 to the second end 101. The first end 100 of each of the soft magnetic elements 10A is arranged at the first end of the magnetic core 1A, and the second end 101 of each of the soft magnetic elements 10A is arranged at the second end of the magnetic core 1A. The soft magnetic elements 10A are each formed integrally. Each of the soft magnetic elements 10A is in the form of a wire comprising a cobalt-iron alloy (or alternatively, for example, a nickel-iron alloy) and is electrically insulated from the other soft magnetic elements 10A by an insulation layer. The cobalt-iron alloy may further comprise chromium and/or molybdenum and/or vanadium (e.g., chromium and molybdenum and vanadium). Other components may also be provided.

Each of the soft magnetic elements 10A follows the C-shape of the magnetic core 1A. Each of the soft magnetic elements 10A is thus designed in the form of a C-shaped bent wire. 3 The course of one of the soft magnetic elements 10A is illustrated with dashed lines. The soft magnetic elements 10A are encapsulated here merely by way of example with a potting compound, so that the magnetic core 1A has a rectangular outer cross-sectional area. Alternatively, the potting compound can be omitted or used in smaller quantities, so that the individual soft magnetic elements 10A are visible from the outside. The soft magnetic elements 10A run parallel to one another. Furthermore, the cross-section can alternatively be different from a rectangular cross-section, particularly if no potting compound is provided. The individual soft magnetic elements 10A are firmly connected to one another.

The magnetic core 1A has a body 14 with a first arm 140A and a second arm 140B. The arms 140A, 140B are each straight in this case. The arms 140A, 140B are connected to each other via a bend 141.

The first ends 100 of the soft magnetic elements 10A are enclosed in a shoe 11A. The second ends 101 of the soft magnetic elements 10A are enclosed in another shoe 11B. The shoes 11A, 11B each have a shaft 111 in the form of a sleeve, wherein the respective shaft 111 encloses the first or second ends 100, 101 of the bundle of soft magnetic elements 10A.

In the present case, the shoe 11A of the first ends 100 and the shoe 11A of the second ends 101 are formed from an SMC (sheet molding compound) material 12, which comprises, for example, a (carbon) fiber-reinforced thermoplastic, in particular a continuous carbon fiber-reinforced thermoplastic. Alternatively, the shoes 11A, 11B could be made, for example, from a plastic and/or by injection molding.

The shoes of 11A, 11B each have a flange 110. This rests on the respective support 203 in the assembled state. The respective flange protrudes from the corresponding shaft 111. The flanges 110 are arranged parallel to each other. The shafts 111 are aligned coaxially with each other along the axial spatial direction A. In the assembled state, the shafts 111 are inserted, for example, into an opening in the respective carrier 203.

By forming the shoes 11A, 11B, the length of the magnetic cores 1A can be reworked.

4 illustrates an exemplary magnetic core 1A for the electric machine 2 and which is designed as the magnetic core 1A according to 3 .

According to 4 However, it is also provided that a base 112 is formed on each of the shoes 11A, 11B, which covers the ends of the soft magnetic elements 10A. The bases 112 are aligned parallel to one another. The bases 112 comprise, for example, an electrically insulating material or consist thereof. However, the bases 112 are optional and can also be omitted. The shoes 11A, 11B with the bases 112 can provide a (particularly good) positive connection for the soft magnetic elements 10A.

5A shows a part of a cross section through one of the arms 140A, 140B of the magnetic core 1A according to 3 It can be seen that the soft magnetic elements 10A each have a circular cross-section.

Furthermore, it can be seen that the soft magnetic elements 10A each have a soft magnetic core 102, which is enclosed by insulation 103. The soft magnetic cores 102 are electrically insulated from one another by the insulation 103. The insulation has a thickness of, for example, 5 micrometers.

The soft magnetic elements 10A each have the same cross-sectional shape and the same diameter d. The soft magnetic elements 10A have a diameter d of 0.2 mm (alternatively, e.g., 0.1 mm). This allows for a very high number of individual soft magnetic elements 10A.

According to 5A The soft magnetic elements 10A are arranged in layers, with the layers being arranged in pairs offset from one another, in this case by half a diameter d. This allows a particularly high packing density to be achieved.

Alternatively, the soft magnetic elements 10A may be arranged in cross-section according to a regular, two-dimensional grid, as in 5B Here, the soft magnetic elements 10A of the adjacent layers are aligned with each other. In cross-section, four adjacent soft magnetic elements 10A describe the corners of a square. Also according to 5B the soft magnetic elements 10A have a circular cross-section.

The one in the 5A and 5B The frame shown in each case illustrates the different fill factor due to the different arrangement of the soft magnetic elements 10A. According to 5A a larger fill factor of over 90% is possible.

An adhesive 13 is arranged between the soft magnetic elements 10A, 10B, with which the soft magnetic elements 10A, 10B are glued together.

6 illustrates a magnetic core 1B, of which the electric machine 2 can have a plurality instead of the magnetic cores 1A. The magnetic core according to 6 has a plurality of strip-shaped, soft magnetic elements 10B. The soft magnetic elements 10B each have a rectangular cross-section. The soft magnetic elements 10B are stacked one above the other along the radial spatial direction R. Furthermore, a plurality of soft magnetic elements 10B, here two, are arranged next to one another (and accordingly offset from one another) along the tangential spatial direction T. The soft magnetic elements 10B are thus segmented in two spatial directions.

The magnetic core 10B has a step 142 at each end. Thus, the magnetic core 1B has a smaller width at its ends than between them. This allows the magnetic core 1B to be easily inserted into the supports 203 with a positive fit.

7 illustrates how a wire 6 can be produced, for example, which can be used to produce the soft magnetic elements 10A, 10B.

For this purpose, an undrawn wire U is drawn through a drawing die 4 to produce the wire 6. The drawing die 4 comprises an insert 40. The insert 40 has a through-hole with a diameter that decreases toward one end. By pulling on the wire 6, the material of the undrawn wire U can be drawn through the insert 40 to produce the wire 6.

The wire 6 thus produced can then, as in 8 shown, are wound around a mandrel 8. The wire 6 is unwound, for example, from a roll 7. The roll 7 is rotated around the mandrel, for example, or the mandrel 8 is turned. In this case, the mandrel 8 has a hexagonal cross-section, although other shapes are also conceivable. By winding the wire 6 onto the mandrel 8, a wire winding 5 is created.

An injection molding S is then injected onto the wire winding 5, see 9 , in particular a plastic, and then the injection molding S is cured. A tool used here can have an elastomer surface to seal the surface of the magnetic cores 1A, 1B.

This creates a winding body W that forms a self-contained ring. Several soft magnetic elements 10A, 10B can then be formed from this by cutting the winding body W into several parts using a cutting tool 9. Each of the resulting six parts can then be used as a magnetic core 1A, 1B. The shoes 11A, 11B can already be formed on the magnetic cores 1A (by injection molding S).

The soft magnetic elements 10A, 10B are therefore designed and arranged in the form of a section of a winding.

The 10A and 10B further illustrate that material can be molded onto the surface from multiple sides, particularly four sides, by means of an adhesive bond, e.g., by resin impregnation or bonding varnish. The material then penetrates between the individual soft magnetic elements 10A. For example, the wire winding 5 (and/or previously the wire 6) is impregnated by trickling, pressure, and/or vacuum-pressure, particularly with a low-viscosity resin. Likewise, the aforementioned bonding varnish can be used, e.g., with heat treatment and/or compression. It is also conceivable to produce the shoes 11A, 11B separately and then bond them together using resin or bonding varnish.

11 illustrates a method for producing a magnetic core 1A, 1B for an electrical machine 2. The method comprises the following steps.

Step S10: Winding at least one wire 6 to form a self-contained winding body W with a plurality of wire windings 5, wherein the at least one wire 6 comprises a soft magnetic material.

Step S11 (optional): The wire windings 5 are compressed.

Step S12 (optional): A heat treatment is carried out (e.g., the wire windings 5 are heated to a temperature of 700°C to 800°C; such heating can be carried out alternatively or additionally before applying an insulating layer) in order to reduce stresses in the material and to adjust the magnetic properties.

Step S13 (optional): The winding body is impregnated, e.g., with a resin, especially one with low viscosity. This can be easily absorbed by capillary forces between the soft magnetic elements 10A, 10B. Step S13 can also be performed later, e.g., after step S15.

Step S14 (optional): As an alternative to such impregnation, the soft magnetic elements 10A, 10B can be coated with a bonding varnish. A heat treatment then bonds the soft magnetic elements 10A, 10B together.

Step S15: The winding body W is divided to form one or more magnetic cores 1A, 1B, each comprising a plurality of electrically insulated, elongated, soft magnetic elements 10A, 10B. The division can be performed, for example, using EDM or precision sawing. Furthermore, a surface treatment can be performed. Surface etching or another type of surface treatment can be performed to prevent short circuits.

Step S16 (optional): The ends of the soft magnetic elements 10A, 10B can be provided with shoes 11A, 11B, e.g., inserted therein, or the ends are overmolded with the shoes 11A, 11B.

In a further step S17, the plurality of magnetic cores 1A, 1B can then be installed in the electric machine 2. For this purpose, the magnetic cores 1A, 1B can be inserted into openings in the supports 203. Furthermore, a fixed connection can be formed using a resin.

It is understood that the disclosure is not limited to the embodiments described above, and various modifications and improvements may be made without departing from the concepts described herein. Any of the features may be used separately or in combination with any other features, provided they are not mutually exclusive, and the disclosure extends to all combinations and subcombinations. one or more of the features described herein.

List of reference symbols

1A, 1B

magnetic core

10A, 10B

soft magnetic element

100

first end

101

second end

102

soft magnetic core

103

isolation

11A, 11B

shoe

110

flange

111

shaft

112

Floor

12

SMC material

13

adhesive

14

Body

140A, 140B

first, second arm

141

bend

142

Level

2

electric machine

20

stator

200

Sink

203

carrier

21

rotor

210

magnet

211

carrier

22

warehouse

3, 3'

aircraft

30, 30'

hull

31

wing

32

propeller

33

Battery system

4

drawing die

40

Mission

5

Wire winding

6

wire

7

role

8

mandrel

9

Cutting tool

A

axial spatial direction

D

axis of rotation

d

diameter

R

radial spatial direction

S

Injection molding

T

tangential spatial direction

U

naughty wire

W

winding body

Claims (23)

Magnetic core (1A, 1B) for an electrical machine (2), comprising a plurality of elongated, soft-magnetic elements (10A, 10B) which are electrically insulated from one another, at least two of which are arranged offset from one another when viewed in two spatial directions (R, T). Magnetic core (1A, 1B) according to Claim 1 , wherein the soft magnetic elements (10A, 10B) are arranged offset from one another in two mutually perpendicular directions when viewed in a cross section through the magnetic core (1A, 1B). Magnetic core (1B) according to Claim 1 or 2 , wherein the soft magnetic elements (10B) have a rectangular cross-section. Magnetic core (1B) according to one of the preceding claims, wherein the soft magnetic elements (10B) are each designed in the form of a flat strip, wherein at least two strips are arranged one above the other and at least two strips are arranged next to each other. Magnetic core (1A) according to one of the preceding claims, wherein the soft magnetic elements (10A) have a round, oval or elliptical cross-section. Magnetic core (1A, 1B) according to Claim 5 , wherein the soft magnetic elements (10A, 10B) have a diameter (d) of less than 1 mm, less than 0.5 mm or less than 0.2 mm. Magnetic core (1A, 1B) according to one of the preceding claims, wherein the soft magnetic elements (10A, 10B) are formed in the form of bent wires. Magnetic core (1A, 1B) according to one of the preceding claims, wherein the soft magnetic elements (10A, 10B) are arranged in the form of a section of a winding. Magnetic core (1A, 1B) according to one of the preceding claims, wherein the soft magnetic ical elements (10A, 10B) are glued together. Magnetic core (1A, 1B) according to one of the preceding claims, wherein the magnetic core (1A, 1B) is C-shaped, I-shaped or L-shaped. Magnetic core (1A, 1B) according to one of the preceding claims, wherein the soft magnetic elements (10A, 10B) comprise or consist of an alloy comprising iron and cobalt. Magnetic core (1A, 1B) according to one of the preceding claims, wherein the soft magnetic elements (10A, 10B) each extend from a first end (100) to a second end (101), wherein the first ends (100) are enclosed in a shoe (11A) and/or the second ends (101) are enclosed in a shoe (11B). Magnetic core (1A, 1B) according to Claim 12 , wherein the shoe (11A) of the first ends (100) and/or the shoe (11A) of the second ends (101) is/are formed from an SMC material (12). Magnetic core (1A, 1B) according to Claim 12 or 13 , wherein the shoe (11A) of the first ends (100) and/or the shoe (11B) of the second ends (101) has/have a flange (110). An electrical machine (2) comprising: - a stator (20) with at least one magnetic core (1A, 1B) according to one of the preceding claims, and - a rotor (21) rotatably mounted relative to the stator (20). Electrical machine (2) according to Claim 15 , wherein a plurality of the magnetic cores (1A, 1B) are each attached to two spaced-apart supports (203) and hold an electrical coil (200) arranged between the supports (203). Electrical machine (2) according to Claim 15 or 16 , designed in the form of a transverse flux machine. Electrical machine (2) according to Claim 15 or 16 , designed in the form of a radial flux machine or an axial flux machine. Electrical machine (2) according to one of the Claims 15 until 18 , having a double air gap. Vehicle, in particular aircraft (3, 3'), comprising a propeller (32) and the electric machine (2) according to one of the Claims 15 until 19 to drive the propeller (32). Method for producing at least one magnetic core (1A, 1B) for an electrical machine (2), in particular according to one of the Claims 1 until 14 , comprising: - winding (S10) at least one wire (6) to form a self-contained winding body (W) with a plurality of wire windings (5), wherein the at least one wire (6) comprises a soft magnetic material; - dividing (S15) the winding body (W) to form at least one magnetic core (1A, 1B) comprising a plurality of mutually electrically insulated, elongated, soft magnetic elements (10A, 10B). Procedure according to Claim 21 , further comprising the following step, carried out before or after the step (S15) of dividing: - gluing (S13, S14) the wire windings (5) together. Procedure according to Claim 21 or 22 , wherein the soft magnetic elements (10A, 10B) each extend from a first end (100) to a second end (101), the method further comprising the following step: - enclosing (S16) the first ends (100) and the second ends (101) in a respective shoe (11A, 11B).