CN111628581A

CN111628581A - Stator of electric machine

Info

Publication number: CN111628581A
Application number: CN202010123636.0A
Authority: CN
Inventors: K.古特曼; Y.亨; M.霍夫鲍尔; S.埃文斯; K.布劳恩; M.福尔默; P.绍洛伊
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2019-02-28
Filing date: 2020-02-27
Publication date: 2020-09-04
Also published as: DE102019202732A1

Abstract

The stator of the electric machine has a plurality of stator teeth arranged distributed over the circumference for receiving stator windings, wherein a recess which is open toward the axial end and forms a magnetic barrier is introduced into at least one stator tooth, said recess extending over an axial partial length of the stator tooth.

Description

Stator of electric machine

Technical Field

The invention relates to a stator of an electric machine, comprising a plurality of stator teeth which are distributed over the circumference and are intended to receive stator windings.

Background

It is known from EP 2234250 a1 to provide the rotor of a permanent magnet excited machine with a tilt and to arrange auxiliary slots in the stator in order to reduce the cogging torque (rattmotion) in the machine. The auxiliary slots in the stator are dimensioned differently in different axial regions, for which purpose the electric machine is divided axially into a plurality of segments which form end-side end sections and a centrally located intermediate section. The geometry of the end sections arranged on the opposite end side is identically embodied.

A synchronous machine is known from US 2010/0289370 a1, in which the outer contour of the rotor is of undulating design in order to generate a sinusoidal air gap field between the rotor and the stator in order to reduce the cogging torque. In DE 102010041015 a1, the outer contour of the rotor is also of undulating design in order to reduce the cogging torque.

Disclosure of Invention

The stator according to the invention of an electric machine, in particular a permanently excited synchronous machine, has a plurality of stator teeth distributed over the circumference for receiving stator windings. The stator teeth are held on the circumferential stator ring of the stator and extend in the radial direction with respect to the longitudinal axis of the stator. The stator is in particular designed for an internal rotor motor, so that the stator teeth are located on the radially inner side of the stator ring. However, within the scope of the invention, application to an outer rotor machine is also contemplated in which the stator teeth are located on the outside of the stator ring.

On the axial end side of the stator, a recess is introduced into at least one stator tooth, which recess forms a magnetic flux barrier (flussbarrier) for reducing leakage flux from the electric machine. The amplitude differences and the phase shift effects between the axial end sides of the electric machine and the center section can be compensated by the magnetic flux barriers. The recesses forming the magnetic flux barriers extend only over a partial length in the axial direction of the stator teeth, so that no axially through openings are formed in the stator teeth, which openings extend over the entire axial length of the stator. The clearance portion forming a magnetic flux barrier reduces cogging torque and torque ripple during load operation.

It is also advantageous that the induced voltage and the motor torque are influenced only minimally under load, so that the advantages of the homogenization of the torque are combined with a high efficiency of the electric machine.

In an advantageous embodiment, the recess forming the magnetic flux barrier is arranged spaced apart from the peripheral side of the stator tooth. Accordingly, the clearance does not extend to the sides of the stator teeth, but is instead spaced from each side. The recess is introduced into the stator tooth in the form of a depression, which is configured only axially open, so that a surrounding wall delimiting the depression is provided.

In a further advantageous embodiment, the recess is introduced into the stator tooth symmetrically with respect to the middle longitudinal axis of the stator tooth.

Accordingly, the spacing is as large as the left and right flanks of the stator teeth.

According to a further advantageous embodiment, corresponding recesses are introduced on the plurality of stator teeth. It may be expedient to provide such recesses on all stator teeth. In an alternative embodiment, it is also possible for only a part of the stator teeth, for example only each second stator tooth, to be provided with a recess.

According to a further advantageous embodiment, the recesses are each introduced into the stator teeth on two opposite axial end faces of the stator teeth. The recesses on the opposite sides of the stator teeth are in particular embodied mirror-symmetrically to one another. In this case, it is particularly advantageous if a recess is introduced into each stator tooth provided with a recess on two opposite axial end sides.

According to a further advantageous embodiment, the recess has a rectangular or at least approximately rectangular cross-sectional shape. If necessary, it may be expedient, however, for the basic shape to be embodied exclusively as a rectangle and, superimposed on the basic shape, to provide non-linear, for example wavy, side walls or to provide rounded corners of the rectangular basic shape.

According to a further advantageous embodiment, the cross-sectional shape of the recess can be freely selected and is configured, for example, in the form of a Spline (Spline).

According to a further advantageous embodiment, the stator consists of a plurality of individual stator laminations stacked on top of one another. The recess is introduced into at least one, preferably a plurality of stator laminations adjacent to the end face. At least one stator lamination from the center section of the lamination stack is embodied without a recess. This ensures that even in the case of two recesses arranged on axially opposite end sides, no through-openings extending over the entire axial length of the stator are formed.

According to a further advantageous embodiment, the stator is designed in an inclined manner and accordingly has an inclination angle which is, for example, in the order of up to 30 ° with respect to the longitudinal axis of the stator. The tilting of the stator results in an additional reduction of cogging torque and torque ripple. In addition to or alternatively to the inclination of the stator, it is also possible to set the inclination of the rotor.

According to a further advantageous embodiment, the recess has an extension in the radial direction which, viewed in the peripheral direction, is smaller than the width of the toothed bar. The extension of the recess in the peripheral direction is, for example, 0.5 to 0.75 times the width of the toothed bar. The tooth bar of the stator tooth is arranged directly on the stator ring and is the carrier of the tooth head on the open end side.

The recess has, for example, an extension in the radial direction which lies in a range of values which can be one to two times the extension in the circumferential direction. According to a further advantageous embodiment, the extension in the axial direction (axial depth of the recess) is 0.75 to 1.25 times the extension in the peripheral direction.

According to a further advantageous embodiment, the recess is located in the tooth head in the radial direction or in the transition between the toothed shaft and the tooth head, so that the recess adjoins the tooth head. It may be expedient if the recess is offset radially with respect to the inner radius of the stator (in the case of an inner rotor) by an amount corresponding to 0.1 to 0.3 times the overall radial extent of the toothed shaft and of the toothed head. Thus, even in this parameterized position specification, the recess is located in the tooth head or adjacent to the tooth head.

The invention further relates to an electric machine, in particular a permanent magnet synchronous machine, having a stator and a rotor as described above.

If necessary, a magnetically neutral bearing pin can be inserted into the recess. The support pin, for example a bolt, can be used for fastening a further component belonging to the electric machine, for example for fastening the end shield. A rigid connection between the end shield and the stator is ensured by means of the bearing pin or bearing pins, whereby, in the event of forces, for example during winding of the stator teeth, a relative movement between the stator and the end shield is precluded or at least reduced.

The bearing pin is made of a plastic material, for example. The bearing pin can be inserted into the recess with an oversize in order to ensure a fixed seating of the bearing pin in the recess. Based on the embodiment consisting of magnetically neutral material, the bearing pin has no influence on the magnetic circuit of the electric machine.

In the case of an inclined stator (which is composed of individual stator laminations), it may be expedient if the uppermost stator lamination on the end face is modified in such a way that a support edge is formed on the recess, which ensures centering and axial alignment of the bearing pin.

Drawings

Further advantages and suitable embodiments result from the further claims, the description of the figures and the figures. Wherein:

fig. 1 shows a perspective view of a stator of an electric machine, the stator having a plurality of radially inwardly extending stator teeth arranged on an outer stator ring, the stator teeth each having a rectangular recess on an axial end face;

fig. 2 shows a representation of a stator corresponding to fig. 1, which however has a recess in the form of a spline;

fig. 3 shows a stator tooth formed by a plurality of stator laminations stacked on one another;

FIG. 4 shows a top view of a stator tooth with a load bearing pin installed;

fig. 5 shows a graph of cogging torque as a function of rotor angle with and without a clearance in the stator teeth.

Detailed Description

In the drawings, like components are provided with like reference numerals.

Fig. 1 shows a stator 1 of a permanently excited synchronous machine designed as an inner rotor. The stator 1 has an outer, circumferential stator ring 2, on the inner side of which a plurality of stator teeth 3 are arranged distributed over the circumference, which extend radially inward and serve to accommodate a stator winding for generating an alternating electromagnetic field. Each stator tooth 3 comprises a toothed bar 4 connected to the stator ring 2 and a radially inner toothed head 5, which is embodied so as to be widened relative to the toothed bar 4. The stator 1 is embodied at an angle and has an angle of inclination α with respect to the longitudinal axis of the stator, wherein the angle α is in the range of values up to a maximum of 30 °.

A hollow 6 is introduced into each stator tooth 3, the hollow having a function of forming a magnetic flux block for reducing leakage flux in the axial direction. The recesses 6 are located on the axial end sides of the stator teeth 3, wherein such recesses 6 are each introduced on two opposite axial end sides of each stator tooth 3. The recess 6 in the stator tooth 3 is formed mirror-symmetrically with respect to a central longitudinal plane through the stator tooth 3. The recess 6 is located directly adjacent to the radially inner tooth head 5 or projects into the tooth head 5, which is embodied so as to be widened relative to the toothed bar 4.

Each stator tooth 3 of the stator 1 carries a recess 6 on two opposite axial end sides.

The recess 6 is open only toward the axial end face and is otherwise spaced apart from the left and right peripheral sides of the stator tooth 3 and also from the radially inner side of the tooth head 5. Furthermore, the axial depth of the recess 6 is smaller than the axial length of the stator 1 and the stator teeth 3, so that the recess 6 extends only over a partial length in the axial direction of the stator teeth 3 and no axially through-openings are formed.

In the embodiment according to fig. 1, the cut-outs 6 have a rectangular cross-sectional shape. The hollow 6 extends longitudinally in the radial direction or in the peripheral direction, so that the extension in the radial direction is greater than the extension in the peripheral direction, or conversely the extension in the peripheral direction is greater than the extension in the radial direction. For example, it may be expedient for the recess 6 to have an extension in the peripheral direction which, viewed in the peripheral direction, is 0.4 to 0.6 times the width of the toothed bar. In the radial direction, it may furthermore be expedient for the extension to be in the range of values which is 0.5 to twice as large as the extension in the peripheral direction. The axial depth of the recess 6 is illustratively in the range of values from one to 1.5 times the extension in the circumferential direction.

The recess 6 is located essentially in the toothed bar 4 and adjoins the widened tooth head 5 or extends into the widened tooth head 5. The recess 6 is open axially upward and has a circumferential wall, so that the recess 6 is spaced apart from the two left-hand and right-hand peripheral sides of the toothed bar 4 and is also spaced apart radially from the inner radius of the toothed head 5. The radial distance from the inner radius of the tooth head 5 is, for example, 0.1 to 0.3 times the overall radial extension of the toothed shaft 4 and of the tooth head 5.

The embodiment of the stator according to fig. 2 corresponds substantially to the embodiment of the stator according to fig. 1, however with the difference that the recesses 6 in the stator teeth 3 have a different cross-sectional shape. According to fig. 2, the limiting wall region of the recess 6 is embodied according to the type of spline and is configured, for example, in a corrugated or curved manner. The hollow 6 has a greater extension in the peripheral direction than in the radial direction. The hollow 6 has approximately the contour of "8".

As can be seen from fig. 3, the stator 1 is constructed from a plurality of stator laminations 7 stacked on top of one another. The stator laminations are stacked on top of each other at an angle to achieve the angle of inclination by each lamination 7 in the stack being twisted by a small angle relative to the underlying lamination.

As can be seen from fig. 4, the recess 6 can be used to accommodate a component 8 made of a magnetically neutral material. The component 8 is, for example, a carrier pin or plug which is firmly inserted into the recess 6 and is a carrier axially forward of the end shield of the stator 1, on which the wires of the stator winding are guided. The bearing pins 8 are firmly located in the recesses 6 and ensure a rigid connection between the stator 1 and the end shield. Since the carrier pin 8 consists of a magnetically neutral material, the magnetic flux is not altered by the carrier pin 8.

The carrier pin 8 can be oversized relative to the recess 6 in order to ensure a fixed seating of the carrier pin 8 in the recess 6. In the case of an inclined stator consisting of a plurality of stator laminations stacked on one another, it may be expedient if the uppermost stator lamination is moved back slightly counter to the direction of inclination, so that the uppermost stator lamination forms a support edge for the support pins and the support pins can be mounted with an axial orientation.

Fig. 5 shows a diagram with a variation of the cogging torque as a function of the rotor position. The cogging torque 9 with a small amplitude is formed when using the stator according to the invention, the stator teeth of which are provided with recesses on two opposing end sides. For comparison, the cogging torque 10 of a conventional stator is shown, which does not have such a clearance. The cogging torque 9 of the stator according to the invention is about 80% less than the cogging torque 10 in the conventional stator.

Claims

1. Stator of an electric machine having a plurality of stator teeth (3) arranged distributed over the circumference for receiving stator windings, characterized in that a magnetically hindered recess (6) which is open toward the axial end face and which forms a magnetic barrier is introduced into at least one stator tooth (3), said recess extending over a partial length of the stator tooth (3) in the axial direction.

2. A stator according to claim 1, characterized in that the space (6) forming a magnetic barrier is arranged spaced apart from the peripheral side of the stator teeth (3).

3. Stator according to claim 1 or 2, characterized in that the stator teeth (3) have a tooth bar (4) and a tooth head (5) held on a stator ring (2), wherein a recess (6) forming the magnetic barrier is arranged in the tooth head (5) or in abutment with the tooth head (5).

4. A stator according to any one of claims 1 to 3, characterized in that on the opposite axial end sides of the stator teeth (3) a clearance (6) is introduced into the stator teeth (3), respectively.

5. Stator according to claim 4, characterized in that the recesses (6) are configured mirror-symmetrically to one another on opposite sides of the stator teeth (3).

6. A stator according to any of claims 1-5, characterized in that the space (6) has a rectangular or approximately rectangular cross-sectional shape.

7. Stator according to one of claims 1 to 6, characterized in that the stator (1) consists of a plurality of individual stator laminations (7), wherein the recesses (6) are introduced into one or more stator laminations (7) adjacent to the end face and at least one intermediate stator lamination (7) is embodied without recesses (6).

8. A stator according to any of claims 1-7, characterized in that the stator (1) has inclined stator teeth (3).

9. Stator according to any of claims 1 to 8, characterized in that the recess (6) has an extension in the circumferential direction which is 0.4 to 0.6 times the width of the toothed bar (4).

10. A stator according to claim 9, characterized in that the stay (6) has an extension in the radial direction which is 0.5 to twice as long as the extension in the peripheral direction.

11. A stator according to claim 9 or 10, characterized in that the stay (6) has an extension in the axial direction which is 1.0 to 1.5 times the extension in the circumferential direction.

12. Stator according to any of claims 1 to 11, characterized in that the centre point of the recess (6) is radially offset with respect to the inner radius of the stator (1) with respect to the radial direction by an amount corresponding to 0.1 to 0.3 times the overall radial extension of the toothed bar (4) and the toothed head (5).

13. A stator according to any of claims 1-12, characterized in that a magnetically neutral carrier pin (8) is mounted into the recess (6).

14. Electrical machine with a stator (1) according to any of claims 1 to 13 and a rotor.

15. The electric machine according to claim 14, characterized by being an embodiment of a permanent magnet excited synchronous machine.