Electric machine having a stator and stranded conductor winding

Abstract

The invention relates to an electric machine (1) having a stator (2) which has a conductor (3, 4, 5), wherein the conductor (3, 4, 5) is designed as a stranded conductor having a plurality of strands (6), and forms at least one coil (11) by virtue of windings (7, 8, 9, 10) and is surrounded on the outer side by a basic insulation (12).

Description

[0001] P221571 - 1 - Electrical machine with a stator and stranded conductor winding The invention relates to an electrical machine with a stator having a conductor. Coil wires are used in electrical machines. The coil wires are penetrated by a stray magnetic field. This inevitably leads to eddy current losses in the conductors. To minimize these eddy current losses, the cross-section of the coil wires can be reduced. In return, the number of turns is generally increased in order to achieve a sufficient total current in the stator slots. To comply with the voltage limit, several coils with a high number of turns are connected in parallel in the stator. Opposite coils are connected in series. Due to the high number of coils and turns formed on the stators, the wiring is very complex.For this reason, only conventional copper wires are used for the windings in series production. Because the connections are very complex, this leads to a very high design and assembly effort. Furthermore, the parallel connections mentioned above lead to additional circulating current losses. This is because, due to manufacturing or design constraints, not all coils and their connections, as well as the magnets, may be exactly symmetrical. However, these additional losses cannot be measured separately. The use of conventional copper wires as conductors, however, has the problem that they have a very high proportion of insulation. Due to the high number of turns in the coil, the overall insulation content is correspondingly very high. Accordingly, the coil is largely made of insulating material, which increases the cross-section of the coil.The object of the present invention is to eliminate the disadvantages mentioned or at least (partially) alleviate them. The focus is on the P221571 - 2 - eddy current losses, which must be minimized. Furthermore, the circulating current losses must be eliminated. This is achieved in a generic electrical machine in that the conductor is designed as a stranded conductor having a large number of strands, and at least one coil is formed by means of (e.g., two, three, four, five, six or more) turns and is surrounded on the outside by basic insulation. Stranded conductors have the advantage that they can minimize eddy current losses. With a small number of turns, the basic insulation, i.e. the insulation of the outside of the stranded conductors, can be designed with thin walls. This has the advantage that there is no enormous disadvantage in terms of installation space. As a result, problematic slot insulation can be dispensed with.It is advantageous if the basic insulation has a wall thickness of between 150 µm and 500 µm. Advantageous embodiments are claimed in the subclaims and are explained in more detail below. Furthermore, at least one of the strands or all of the strands can be surrounded by their own additional insulation, wherein it is preferred that the individual strands are systematically stranded together in at least one stage. If the stranded conductor already has basic insulation, the additional insulation of the strand or of all of the strands can be reduced to a minimum. Furthermore, the conductor can be a plurality of conductors, wherein the number of conductors corresponds at least to or exactly to the number of desired phases, wherein each conductor forms at least one coil. If the number of desired phases is kept low, the number of conductors is also low, thereby reducing the wiring effort and installation space.In a further advantageous embodiment, the number of conductors can be a multiple of the desired number of phases. In addition, the number of conductors can be twice the desired number of phases. Furthermore, the number of conductors can correspond to the number of desired phases P221571 - 3 - It is particularly advantageous if the additional insulation has a wall thickness of between 1 µm and 20 µm. The wall thickness of the additional insulation depends on the selected manufacturing process. In addition, there can be 12 coils per phase. It is advantageous if the windings are wound on one strand. Several coils can be wound from one conductor to form turns. This means that only one conductor is necessary per phase, which keeps the wiring effort to a minimum. It is also advantageous if all conductors of a phase are connected in series. The series connection ensures that the wiring effort is also kept to a minimum.In addition, circulating current losses are eliminated by eliminating the parallel connection. Furthermore, a slot length can be a multiple of a strand lay length, the length of the repeating twisting pattern. This allows the induced voltages within the slot among the individual strands to be standardized and circulating currents in short-circuited strands to be reduced. It is advantageous if 36 coils with four turns each are divided into two stator halves and three phases are formed by three conductors. The stator halves are arranged so that a rotor is located between the two stator halves. By using only three conductors, the connection between the stator halves is reduced to a minimum. The respective conductors are transferred from one stator half to the other stator half. Therefore, only one connection per phase is necessary between the stator halves. This reduces the wiring effort and uses less installation space.In a further advantageous embodiment, a plurality of coils can be separated into two coil halves, each with a half-number of turns, in order to carry out the P221571 - 4 - connection between the two coil halves on the coil opposite the terminal. Furthermore, one or more phases can be connected on the inner and / or outer diameter of the coils. Accordingly, the phases can be connected only on the inner diameter, only on the outer diameter, or some of the phases are connected on the inner diameter and another part on the outer diameter. A special feature of connection on the inner diameter is that the first coil is designed with a non-integer number of turns, since the conductor fills up the missing turns during the return path, i.e. in order to continue the connection to the other stator half. Furthermore, the electrical machine can be designed as an axial flux machine, in particular as a motor.An axial flux machine has the advantages of having a shorter axial length and improved efficiency compared to a radial flux machine. A higher torque is achieved with a constant outer diameter. Furthermore, a lower iron volume in the active part results in higher efficiency over a wider speed range. It is particularly advantageous if the individual strands are twisted / stranded together in such a way that each strand is located on the outside and inside of the conductor formed by the strands. This allows each strand to be exposed to coolant from the outside. This results in a particularly thermally optimized winding. Various advantageous embodiments of the invention are explained in more detail below with reference to a drawing with figures. These show: Fig. 1 an exploded view of an electrical machine according to the invention, P221571 - 5 - Fig.2 shows a sectional view of part of a stator half in a first embodiment, Fig. 3 shows a sectional view of part of a stator half in a second embodiment, Fig. 4 shows a schematic view of the two stator halves with a first connection option, Fig. 5 shows a schematic view of the two stator halves with a second connection option. The figures are merely schematic in nature and serve exclusively to understand the invention. The same elements are provided with the same reference numerals. Features of the individual embodiments can be interchanged and used alternatively / cumulatively. Fig. 1 shows an exploded view of an electrical machine 1 according to the invention. The electrical machine 1 has a stator 2 which has a conductor 3, 4, 5. The conductor 3, 4, 5 is formed using stranded wires 6 (see Fig. 2).The conductor 3, 4, 5, here designed as a stranded conductor, has a plurality of strands 6. A coil 11 is formed by means of windings 7, 8, 9, 10 (shown in detail in Fig. 2), and on the outside, the conductor 3, 4, 5 is surrounded by a base insulation 12 (shown in Fig. 2). The stator 2 is divided into two stator halves 13, 14, a first stator half 13 and a second stator half 14. The first stator half 13 and the second stator half 14 are arranged such that a rotor 15 is arranged between the two stator halves 13, 14 in the axial direction. The stator halves 13, 14 each have a plurality of stator teeth 16 arranged in the circumferential direction along the stator halves 12, 13. Each stator tooth 16 has a coil 11. The stator teeth are formed on a stator yoke 17, which mirrors the bottom of the respective stator half 13, 14. P221571 - 6 - In Fig.2 shows a sectional view through a stator half 13, 14, in which the section is crossed by a stator tooth 16. Based on this sectional view, the representation of the conductors 3, 4, 5 with the strands 6 can be described in more detail. In the embodiment shown here, the coil 11 has a total of four windings 7, 8, 9, 10. The windings 7, 8, 9, 10 are single-layered. The conductor 3, 4, 5 shown here is shown as a stranded conductor. The stranded conductor has a plurality of individual strands 6. The embodiment has a total of twenty strands 6 per conductor 3, 4, 5. The strands 6 are arranged such that they are surrounded by the base insulation 12. In this case, five strands 6 are shown one above the other in the radial direction and a total of four strands 6 are arranged one after the other in the axial direction. Accordingly, the conductor 3, 4, 5 has a total of twenty strands 6.The strands 6 each have additional insulation 22. Fig. 3 shows a sectional view identical to that in Fig. 2. In comparison to Fig. 2, the arrangement of the windings 7, 8, 9, 10 and the strands 6 in the conductor 3, 4, 5 is different compared to Fig. 2. In the embodiment shown, the total of four windings 7, 8, 9, 10 are not arranged in a single layer, but two windings 7, 8, 9, 10 are wound one above the other, i.e. a two-layer design. In the conductor 3, 4, 5, the strands 6 are arranged such that a total of ten strands 6 are arranged next to one another in the axial direction and two strands 6 are arranged in the radial direction. The total number of strands 6 in the conductors 3, 4, 5 is also twenty strands 6, as in Fig. 2. Fig. 4 shows the interconnection of the stator halves 13, 14. As already described in Fig. 1, the stator 2 is divided into two stator halves 13, 14.The circuitry is designed such that the first stator half 13 and the second stator half 14 are connected via conductors 3, 4, and 5. In the illustrated embodiment, the stator halves 13 and 14 are each configured with 18 coils 11. The stator 2 therefore has a total of 36 coils 11. The coils 11 are divided into three phases 18, 19, and 20. The coils 6 are arranged in the phases 18, 19, and 20 such that they alternate in the circumferential direction. With 18 coils 11 per stator half 13 and 14, a total of six coils 11 are depicted per phase 18, 19, and 20. In the illustrated embodiment, the conductors 3, 4, 5 are designed such that one conductor 3, 4, 5 is used for winding the coils 11 per phase 18, 19, 20.The conductors 3, 4, 5 of the respective phase 18, 19, 20 begin at a terminal (not shown), from which the conductor 3, 4, 5 in each case reaches a first stator tooth 16 and there the winding around the stator teeth 16 begins. Once the respective conductor 3, 4, 5 of the respective phase 18, 19, 20 has been wound around all stator teeth 16 of the first stator half 13, the conductor 3, 4, 5 leads to the second stator half 14, where the conductor 3, 4, 5 is wound around the respective stator teeth 16 in the same way as in the first stator half 13. If the three conductors 3, 4, 5 are also wound around their respective stator teeth 16 of the respective phases 18, 19, 20, the conductors 3, 4, 5 end in a star point 21. In the embodiment shown here, the individual coils 11 of the stator teeth 16 of the respective phase 18, 19, 20 are connected via the outer diameter of the stator halves 13, 14 via the conductors 3, 4, 5.The winding shown begins at a first stator tooth 16 and moves counterclockwise in the circumferential direction for the first stator half 13 and changes at the second stator half 14 to a first stator tooth 16 of the second stator half 14 and is also wound counterclockwise in the circumferential direction. Fig. 5 shows an alternative connection compared to the connection shown in Fig. 4. In the connection shown here, not all phases 18, 19, 20 are wound over the outer diameter of the respective stator half 13, 14, but for one phase 18, one phase is wound over an inner diameter of the stator halves 13, 14. The other two phases 19, 20 are again wound over the outer diameter as in Fig. 4. If one of the phases 18, 19, 20 is wound over the inner diameter of the stator half 13, 14, the first stator tooth 16 must be wound with a non-integer number of turns 7, 8, 9, 10.If the conductor 3, 4, 5 now runs from the first stator tooth 16 to the other stator teeth 16 of the respective phase 18, 19, 20 on the first stator half P221571 - 8 - 13, the missing turn 5 is rewound during the return conduction to the second stator half 14.

[0002] P221571 PIF - 9 - List of reference symbols 1 electric machine 2 stator 3 first conductor 4 second conductor 5 third conductor 6 stranded wire 7 first winding 8 second winding 9 third winding 10 fourth winding 11 coil 12 basic insulation 13 first stator half 14 second stator half 15 rotor 16 stator tooth 17 stator yoke 18 first phase 19 second phase 20 third phase 21 star point 22 additional insulation

Claims

P221571 - 10 - Patent claims 1. Electrical machine (1) with a stator (2) having a conductor (3, 4, 5), characterized in that the conductor (3, 4, 5) is designed as a stranded conductor, comprising a plurality of strands (6), and forms at least one coil (11) by means of windings (7, 8, 9, 10) and is surrounded on the outside by a basic insulation (12).

2. Electrical machine (1) according to claim 1, characterized in that at least one of the strands (6) or all of the strands (6) is surrounded by its own additional insulation (22), wherein it is preferred that the individual strands are systematically stranded together in at least one stage.

3. Electrical machine (1) according to claim 1 or 2, characterized in that the conductor (3, 4, 5) is a plurality of conductors (3, 4, 5), the number of conductors (3, 4, 5) corresponding at least to or exactly to the number of desired phases (18, 19, 20), each conductor (3, 4, 5) forming at least one coil (11).Electrical machine (1) according to one of claims 1 to 3, characterized in that there are twelve coils (11) per phase (18, 19, 20).

5. Electrical machine (1) according to one of the preceding claims, characterized in that a plurality of coils (11) are wound from a conductor (3, 4, 5) to form turns (7, 8, 9, 10).

6. Electrical machine (1) according to one of claims 3 to 5, characterized in that all conductors (3, 4, 5) of a phase are connected in series.

7. Electrical machine (1) according to one of claims 1 to 6, characterized in that a slot length is a multiple of a strand lay length. P221571 - 11 - 8. Electrical machine (1) according to one of claims 1 to 7, characterized in that 36 coils (11), divided into two stator halves (13, 14) and three phases (18, 19, 20) are formed by three conductors (3, 4, 5).

9. Electrical machine (1) according to one of claims 1 to 8, characterized in that several coils (11) are separated into two coil halves, each with a half-number of turns, in order to carry out the connection between the two coil halves on the coil side opposite the terminal.

10. Electrical machine (1) according to one of claims 1 to 9, characterized in that the electrical machine (1) is designed as an axial flux machine, in particular as a motor.

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