Winding conductor for an electrical machine

Abstract

Winding conductor for an electrical machine, which can be introduced into slots of a stator or rotor of the electrical machine, characterized by an octagonal cross-section of the winding conductor, wherein the octagonal cross-section has in its circumference two long straight first sections (AB, EF) which are aligned parallel to one another, as well as two short sides, each of which comprises two further straight sections (AH, GF and BC, DE) and a curved section (GH, CD) between the further straight sections.

Description

[0001] The invention relates to a winding conductor for electrical machines according to the preamble of claim 1.

[0002] Electrical machines are used to convert electrical energy into mechanical energy or vice versa. An electrical machine designed as a prime mover for a motor vehicle is particularly suitable for use within the drivetrain of a hybrid or fully electric motor vehicle.

[0003] Winding conductors for electrical machines, which are inserted into corresponding slots, are well known in a wide variety of designs. For example, there are windings with conductors made of solid individual wires with round or any rectangular cross-section. A winding conductor can be designed as a long conductor strand that is bent several times according to the specified winding pattern, thus forming, for example, a winding in the electrical machine. However, the winding conductor can also consist of a plurality of different bent conductor pieces (shaped conductors), the conductor legs of which are inserted into the slots and then form the conductor strand via welded ends.

[0004] Winding conductors designed as square wires are used when a better slot coverage is to be achieved compared to round wires with the same cross-sectional area. However, a slight tilt of the square wire during the radial insertion of the winding into the slots can result in compression of the insulating paper previously inserted into the slots. To reduce this tendency to build up, you can either increase the edge radius of each edge or increase the thickness of the insulating paper. This first measure rounds off the edges, which means that less frictional forces act on the insulating paper when the winding is inserted into the slots, thus significantly reducing entrainment and therefore compression of the insulating paper. The second measure increases the kink resistance of the insulating paper, which also reduces the tendency for the paper to be entrained. However, when using thicker insulating paper, the slot width must also be increased or reduced.The conductor width must be reduced. However, a resulting change in the slot geometry would impair the electrical machine's power balance. Rounding and thus flattening the edge radii, on the other hand, results in a reduction in the conductor cross-section, and thus in particular in the copper cross-section of the electrically conductive base body of the winding conductor. If a certain maximum current density in the copper conductor is required for an electrical machine to avoid thermal overload, a reduced conductor cross-section would also require the current through the winding conductor to be reduced, which in turn would impair the electrical machine's power balance.

[0005] Various conductor cross-sections are known from DE 11 2008 000 175 T5. DE 11 2008 000 175 T5 discloses a conductor wire with a square cross-section comprising corners or edges at right angles, a conductor wire with an elongated cross-section comprising corners at right angles, a conductor wire with a substantially square cross-section comprising rounded corners, a conductor wire with a substantially elongated cross-section comprising rounded corners, and a conductor wire with a "racetrack-like" cross-section, which has one pair of opposite sides parallel to each other and the other pair of opposite curved sides. Depending on their design, the conductor cross-sections shown have one or more of the disadvantages described above.For example, especially with winding conductors with an elongated cross-section without rounded edges, as well as with the rounded edges shown with a small rounding radius, the difficulties mentioned above can be expected when inserting the winding conductors into the slots. In contrast, with the winding conductor shown with a "racetrack-like" cross-section, the conductor cross-section is significantly reduced, which excessively increases the current density in the conductor for the same required power of the electrical machine.

[0006] The object of the invention is to provide a winding conductor that has a cross-sectional shape that is both optimized for production technology and optimized for the electrical machine's performance. According to the invention, this object is achieved by the winding conductor according to claim 1.

[0007] Because a winding conductor with an octagonal cross-section has two long, straight first sections in its circumference that are aligned parallel to one another, as well as two short sides, each of which includes two further straight sections and a curved section between the further straight sections, a winding conductor with an optimized cross-section can be provided for windings of electrical machines, which provides a maximized conductor cross-sectional area both from the point of view of the power balance of the electrical machine and a more optimal conductor shape from the point of view of the assembly and production of the electrical machine.

[0008] Especially with flat wire winding conductors, which are stacked one on top of the other in the slots, there is a risk of jamming or the insulation paper being pulled along when the winding conductors are inserted into the slots during production. By dividing the shorter sides of the winding conductor into two straight sections and a curved section in between, the wire width is partially reduced across the height of the winding conductor, thus reducing problems caused by jamming if the conductors twist during insertion into the slots.

[0009] If the winding conductor's conductor cross-section consists of an electrically conductive base body and an electrically insulating material that completely surrounds the base body, and if the cross-sectional area of ​​the winding conductor is determined by the external dimensions of the insulating material, additional insulating paper can be omitted in the slots, or at least a thinner insulating paper can be used. This has the advantage that such an insulated conductor's cross-section is optimized for both maximum current and safe insertion during assembly. An electrically insulating sheath formed by insulating material around the electrically conductive base body can be provided, for example, with a PEEK varnish or a varnish made of polyamideimide (PAI), polyimide (PI), polyetherimide (PEI), or even a suitable multi-layer varnish.The base body can, for example, be a copper core made of Cu ETP, Cu ETP1, Cu OF, Cu OF1, Cu OFEs, or even an aluminum core. However, any other type of material and sheath is also conceivable, as long as the previously described inventive criteria are met.

[0010] The invention is explained in more detail by way of example with reference to the figures. They show schematically and not to scale: Fig. 1 a first preferred embodiment of a winding conductor Fig. 2 a second preferred design of the winding conductor Fig. 3 a third version with partially orthogonal sides Fig. 4 a fourth version with partially orthogonal sides

[0011] The Fig. The cross-section of a winding conductor designed according to the invention, sketched in Figure 1, has two long, straight first sections AB and EF around its circumference. These are the sides with which the winding conductors, which are inserted and stacked in the slots of a stator or rotor, then come into contact with one another. Furthermore, the winding conductor shown here has two further straight sections AH and GF as well as BC and DE on each of its short sides, between which there is a curved section GH and CD. This curved section on each of the two short sides ensures that at least one of the two straight sections on one of the short sides is not aligned orthogonally to the long sections. This creates a cross-section that deviates from an ideal square or rectangle and thus essentially rounds off the winding conductor. Fig. In the design shown in Figure 1, all four corner areas were rounded off by the straight sections AH and GF as well as BC and DE compared to an ideal rectangular wire. If such a winding conductor is inserted into slots in a direction perpendicular to the long straight sections AB and EF, even a possible tilt or twist to the left or right will not cause the winding conductor to become jammed in the slot. The choice of angle alpha for the bent sections GH and CD is a compromise between the desired power balance and simplified manufacturing. Fig. 1, the wrap alpha has the same circle center for both short sides, while in the Fig. 2 shown version is different, so that the Fig. 2 shown conductor cross-sectional area is larger than that in Fig.1, whereby a higher fill factor in the slots and thus a better power balance can be achieved. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 11 2008 000 175 T5

[0005]

Claims

[1] Winding conductor for an electrical machine, which can be inserted into slots of a stator or rotor of the electrical machine, characterized by an octagonal cross-section of the winding conductor, wherein the octagonal cross-section has in its circumference two long straight first sections (AB, EF) which are aligned parallel to each other, as well as two short sides, each comprising two further straight sections (AH, GF and BC, DE) and a curved section (GH, CD) between the further straight sections. [2] Winding conductor according to claim 1 characterized by that the winding conductor consists in cross-section of an electrically conductive base body and an electrically insulating material that surrounds the base body, wherein the cross-section of the winding conductor is determined by the external dimensions of the insulating material.

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